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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES Iso and non-iso architected Cr/TiN multilayers thin films with constant thickness and composition were deposited by magnetron sputtering aiming to study the influence of different architectures over coatings structures and properties. Glow-discharge optical emission spectroscopy (GD-OES) and scanning electron microscopy with field emission gun (SEM-FEG) analyses showed that all multilayers presented sharp interfaces and dense nanostructures, with columnar growth tendency and grain sizes varying according to layer thickness. Grazing Incidence X-Ray Diffraction (GAXRD) analyses showed that multilayers consist of polycrystalline α-Cr and δ-TiN phases with a preferential growth in Cr(110) plane. The overlapping of TiN onto metallic layers leads to a high amorphization degree of its structure, although TiN layers thicker than 50 nm demonstrated increased crystallinity in plane TiN(200). Nanohardness tests registered hardness values for all multilayers of around 16.2 GPa, evidencing that different distribution order of layers did not significantly influence this property. The low values of H/E noted in 0.08 indicate that all multilayers suffer nanoplastic deformations, being adequate only for non-contact or low intensity applications. Oxidation tests revealed the iso-structured architecture thin film presented an improved oxidation resistance due to a balance between Cr amount and TiN layers with modarate crystallinity at the upper period. Corrosion tests highlighted the graduated architecture with increasing amount of Cr towards the surface as the most suitable to optimize the corrosion resistance. Filmes finos do tipo multicamadas Cr/TiN iso e não iso-estruturadas com espessura e composição constantes foram depositados por magnetron sputtering com o objetivo de estudar a influência de diferentes arquiteturas nas estruturas e propriedades dos revestimentos. Análises de espectroscopia de emissão óptica por descarga luminescente (GD-OES) e microscopia eletrônica de varredura com emissão de campo (MEV-FEG) mostraram que todas as multicamadas apresentaram interfaces uniformes e nanoestruturas densas, com tendência de crescimento colunar e tamanhos de grão variando de acordo com a espessura da camada. Análises de difração de raios X com ângulo rasante (GAXRD) mostraram que as multicamadas consistem em fases policristalinas de α-Cr e δ-TiN, com crescimento preferencial no plano Cr(110). A sobreposição de TiN nas camadas metálicas de Cr levou a um alto grau de amorfização da estrutura δ-TiN, embora camadas de TiN mais espessas que 50 nm tenham demonstrado aumento de cristalinidade no plano TiN(200). Testes de nanodureza registraram valores de dureza para todas as multicamadas em torno de 16,2 GPa, evidenciando que diferentes ordens de distribuição das camadas não influenciaram significativamente essa propriedade. Baixos valores para o fator H/E, notados em 0,08, indicaram que as multicamadas tendem a sofrer deformações nanoplásticas, sendo adequadas apenas para aplicações sem contato ou de baixa intensidade. Testes de oxidação revelaram que o filme fino com arquitetura iso-estruturada apresentou maior resistência à oxidação devido ao equilíbrio entre a quantidade de cromo e a camada de TiN com certo grau de cristalinidade no período de topo. Ensaios de corrosão destacaram a arquitetura graduada com aumento da quantidade de Cr em direção à superfície e a isoestruturada como as mais adequadas para otimizar a resistência à corrosão. São Cristóvão, SE

CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Este trabalho apresenta a síntese e caracterização de híbridos de nanotubos de carbono (NTC) ligados covalentemente a copolímeros conjugados formados por 3,4-etilenodioxitiofeno (EDOT) e derivados de pirrol (pirrol - Py, metilpirrol - MPy e 3-(pirrol-1-metil)piridina - PyMP). Os NTCs foram funcionalizados em três etapas, que consistiu na oxidação inicial com ácido sulfúrico e ácido nítrico concentrado (3:1 v/v), seguido por um processo de amidação (1,3-diaminopropano - DAP ou tetraetilenopentamina - TEPA) e adição da unidade monomérica via ácido tiofeno carboxílico (ATC). Posteriormente, a copolimerização foi usada para a formação de seis novos híbridos: NTC-TEPA-ATC-P(EDOT-co-Py) (H1), NTC-TEPA-ATC-P(EDOT-co-MPy) (H2), NTC-TEPA-ATC-P(EDOT-co-PyMP) (H3), NTC-DAP-ATC-P(EDOT-co-Py) (H4), NTC-DAP-ATC-P(EDOT-co-MPy) (H5) e NTC-DAP-ATC-P(EDOT-co-PyMP) (H6). Todos os híbridos foram caracterizados por técnicas espectroscópicas (Infravermelho - IV, Raman e Espectroscopia de Fotoelétrons por Raios-X - XPS), térmicas (Termogravimetria - TG) e morfológicas (Microscopia Eletrônica de Transmissão - MET). As técnicas utilizadas confirmaram a cobertura do material polimérico ao longo da NTC e sua composição polimérica de aproximadamente 45% em massa no híbrido, correspondendo à formação molar de 1:1 NTC:copolímeros conjugados. Os estudos de comportamento eletroquímico e elétrico de todos os híbridos foram realizados, indicando sua potencial aplicação como material de eletrodo em supercapacitores (SCs), com seus resultados de condutividade elétrica até sessenta vezes maiores que o copolímero correspondente. A confecção dos dispositivos (SCs) completos permitiu analisar a versatilidade dos materiais em diferentes meios eletrolíticos (acetonitrila e água), a partir de um estudo com o híbrido H3. As capacitâncias das células simétricas obtidas para os SCs baseados em H3 foram 56% e 115% superior ao das células preparadas com o NTC não modificado em meio orgânico e aquoso, respectivamente. As células completas também exibiram excelente ciclabilidade com 81,3% (aquoso) e 77,5% (orgânico) de retenção de capacitância após 5000 ciclos. Outro estudo realizado partiu da comparação dos híbridos (H5 e H6) com seus materiais precursores utilizando solução aquosa de LiClO4 como eletrólito. Os híbridos H5 (109,4 F g-1) e H6 (139,6 F g-1) sintetizados apresentaram uma melhora nos valores de capacitância em comparação com o sistema de NTC puro (60,9 F g-1) e com os copolímeros de origem (69,2 F g-1 para P(EDOT-co-MPy) e 64,9 F g-1 para o P(EDOT-co-PyMP)). A boa retenção de capacitância em função da corrente aplicada nas células também foi melhorada como resultado de um aprimoramento na transferência de carga nos híbridos. Os dispositivos apresentaram alto desempenho com excelente estabilidade de ciclagem, em comparação com a baixa ciclabilidade dos copolímeros conjugados, mesmo após 20000 ciclos. As propriedades dos dispositivos indicam a viabilidade da abordagem sintética usada, mostrando que os híbridos preparados são materiais promissores para uso em supercapacitores altamente cicláveis. This work presents the synthesis and characterization of carbon nanotube (CNT) hybrids covalently bounded to conjugated copolymers formed by 3,4-ethylenedioxythiophene (EDOT) and pyrrole derivatives (pyrrole - Py, methylpyrrole - MPy and 3-(pyrrol-1- ylmethyl)pyridine - PyMP). The CNTs were functionalized in three stages, which consisted of their initial oxidation with sulfuric acid and concentrated nitric acid (3:1 v/v), followed by an amidation process (1,3-diaminopropane - DAP or tetraethylenepentamine - TEPA) and addition of the monomeric unit via thiophene carboxylic acid (TCA). Subsequently, copolymerization was used to form six new hybrids: CNT-TEPA-TCA-P(EDOT-co-Py) (H1), CNT-TEPA-TCA-P(EDOT-co-MPy) (H2), CNT-TEPA-TCA-P(EDOT-co-PyMP) (H3), CNT-DAP-TCA-P(EDOT-co-Py) (H4), CNT-DAP-TCA-P(EDOT-co-MPy) (H5) and CNT-DAP-TCA-P(EDOT-co-PyMP) (H6). All hybrids were characterized by spectroscopic techniques (Infrared - IR, Raman, and X-ray Photoelectron Spectroscopy - XPS), thermal (Thermogravimetry - TG) and morphological (Transmission Electron Microscopy - MET). The techniques used confirmed the coverage of the polymeric material throughout the CNT and their polymeric composition of approximately 45% by mass in the hybrid, corresponding to the molar formation of 1:1 CNT:conjugated copolymers. The studies of the electrochemical and electrical behavior of all hybrids were carried out, indicating their potential application as electrode material in supercapacitors (SCs), with their electrical conductivity results up to sixty times greater than the corresponding copolymer. The assemble of the complete devices (SCs) allowed us to analyze the versatility of the materials in different electrolytic media (acetonitrile and water), from a study with the H3 hybrid. The capacitances of the symmetrical cells obtained for SCs based on H3 were 56% and 115% higher than that of cells prepared with the unmodified NTC in organic and aqueous media, respectively. Complete cells also exhibited excellent cyclability with 81.3% (aqueous) and 77.5% (organic) capacitance retention after 5000 cycles. Another study carried out started with the comparison of hybrids (H5 and H6) with their precursor materials using aqueous LiClO4 solution as the electrolyte. The hybrids H5 (109.4 F g-1) and H6 (139.6 F g-1) synthesized showed an improvement in capacitance values compared to the pure CNT system (60.9 F g-1) and with the parent copolymers (69.2 F g-1 for P(EDOT-co-MPy) and 64.9 F g-1 for P(EDOT-co-PyMP)). The good retention of capacitance as a function of the current applied to the cells was also improved as a result of an improvement in charge transfer in the hybrids. The devices showed high performance with excellent cycling stability, compared to the low cycling of conjugated copolymers, even after 20000 cycles. The properties of the complete devices indicate the feasibility of the synthetic approach used, showing that the prepared hybrids are promising materials for use in highly cyclable supercapacitors.

Submitted by Alexandre Zirpoli Simões (zirpoli.simoes@unesp.br) on 2020-09-26T17:59:45Z No. of bitstreams: 1 Amoresi-2020_Metallic behavior STO-LAT_versao final vol doi.pdf: 1428668 bytes, checksum: 1fe4199f2f3f22c7fe7cb777d664cb09 (MD5) Approved for entry into archive by Pamella Benevides Gonçalves null (pamella@feg.unesp.br) on 2021-07-26T23:37:48Z (GMT) No. of bitstreams: 1 amoresi_rac_artigo_guara_metallic.pdf: 1428668 bytes, checksum: 1fe4199f2f3f22c7fe7cb777d664cb09 (MD5) Made available in DSpace on 2021-07-26T23:37:48Z (GMT). No. of bitstreams: 1 amoresi_rac_artigo_guara_metallic.pdf: 1428668 bytes, checksum: 1fe4199f2f3f22c7fe7cb777d664cb09 (MD5) Previous issue date: 2020-06-16 Outra Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The search for new and low-power switching devices involving the integration of semiconductor thin films is of interest, and has led to renewed research because such devices may exhibit innovative properties. Here, we investigate the two-dimensional electron gas (2DEG) at the LaAlO3/SrTiO3 interface with metallic and insulator behavior. Insight is offered by quantifying the interface charge distribution associated with structural and electronic order-disorder effects. Variations in the electron conductivity were observed to be associated with different specific clustering arrangements of both Ti and Al cations of the co-exposed surfaces at the interface, i.e., structural and electronic connectivity among the undercoordinated [TiO ]5 and [AlO ]5 clusters. These results indicate facet control as a strategy for enhancing the electric and magnetic properties of a device via the quantum confinement of electron Faculty of Engineering of Guaratingueta, São Paulo State University, UNESP Department of Analytical and Physical Chemistry, University Jaume I (UJI), Castello Department of Physics FederalUniversity of São Carlos, UFSCAR Institute of Physics of São Carlos, University of São Paulo – USP Interdisciplinary Laboratory of Electrochemistry and Ceramics, LIEC, Chemistry Institute, São Paulo State University, UNESP FAPESP: 2013/07296-2. 2017/19143-7. 2018/01914-0. 2019/09296-6 CNPq: 150949/2018-9 Capes - 001

Made available in DSpace on 2020-12-10T20:14:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-06-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) CT-INFRA/FINEP/MCTIC Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) UFPB University of Sydney Australian Synchrotron Australian Research Council The impact of Eu3+ doping at the Sr2+ and Sn4+ sites in SrSnO3 on its structural and electronic properties was studied and correlated with the photocatalytic efficiency. The compounds were synthesized using a modified Pechini method. Refinement of the synchrotron X-ray diffraction (S-XRD) data showed that the samples had an orthorhombic Pbnm symmetry. The incorporation of Eu into the lattice led to increased short- and long-range disorder, inducing additional distortion in the SnO6. XANES measurements revealed that mixed Eu valences (Eu3+ and Eu2+) were present in Eu-doped samples, and DFT calculations confirmed the presence of these ions at Sr2+/Sr4+ sites in the SrSnO3, resulting in changes in the electronic behavior. The catalytic performance toward Remazol yellow dye photodegradation and the catalysts' surface properties were also evaluated. The catalytic efficiency followed the order of Sr(Sn0.99Eu0.01)SnO3 > (Sr0.99Eu0.01)SnO3 > SrSnO3. The order was clearly related to selected-site doping that changed the degree of the inter- and intraoctahedral distortion and the introduction of different Eu midgap states, which apparently favor charge separation upon photoexcitation during photocatalysis. The results shown here are of great importance to the functionalization of SrSnO3 and other perovskite materials by lanthanoid ions, especially Eu3+, for effective applications as photocatalysts. Univ Fed Paraiba, Dept Quim, NPE LACOM, BR-58051085 Joao Pessoa, Paraiba, Brazil Univ Sydney, Sch Chem, Sydney, NSW 2006, Australia Univ Torino, Dipartimento Chim, I-10125 Turin, Italy Univ Fed Rio Grande do Norte, Inst Quim, BR-59078970 Natal, RN, Brazil Univ Estadual Paulista, Grp Simulacao & Modelagem Mol, BR-17033360 Bauru, SP, Brazil Univ Estadual Campinas, Inst Fis Gleb Wataghin, BR-13083859 Campinas, SP, Brazil Univ Sao Paulo, Inst Fis, BR-13563120 Sao Carlos, SP, Brazil Univ Estadual Paulista, INCTMN, LIEC, BR-14800060 Araraquara, SP, Brazil Univ Estadual Paulista, Grp Simulacao & Modelagem Mol, BR-17033360 Bauru, SP, Brazil Univ Estadual Paulista, INCTMN, LIEC, BR-14800060 Araraquara, SP, Brazil CAPES: 001 CNPq: 232680/2014-0 Australian Synchrotron: AS153/PD/10002 Australian Synchrotron: AS153/SXR/10026 CAPES: 88882.317938/201901 CNPq: 420062/2016-5

The increasing need for point-of-care diagnosis has sparked the development of label-free sensing platforms, some of which are based on impedance measurements with biological cells. Here, interdigitated electrodes were functionalized with layer-by-layer (LbL) films of hyaluronan (HA) and chitosan (CHI) to detect prostatic tumor cells (PC3 line). The deposition of LbL films was confirmed with atomic force microscopy and polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), which featured the vibrational modes of the HA top layer capable of interacting specifically with glycoprotein CD44 receptors overexpressed in tumor cells. Though the CHI/HA LbL films cannot be considered as a traditional biosensor due to their limited selectivity, it was possible to distinguish prostate tumor cells in the range from 50 to 600 cells/&micro, L in in vitro experiments with impedance spectroscopy. This was achieved by treating the impedance data with information visualization methods, which confirmed the distinguishing ability of the films by observing the absence of false positives in a series of control experiments. The CD44&ndash, HA interactions may, therefore, be exploited in clinical analyses and point-of-care diagnostics for cancer, particularly if computational methods are used to process the data.

Electrochemical immunosensors have been developed to determine the carbohydrate antigen 19-9 (CA19-9). They are based on screen-printed carbon electrodes (SPCEs) coated with layer-by-layer (LbL) films of carbon black (CB) and polyelectrolytes. Owing to a suitable choice of LbL film architecture, the procedures for immobilization of anti-CA19-9 antibodies on the electrode surfaces were straightforward. Mechanically flexible immunosensors were capable of detecting CA19-9 within a dynamic range of 0.01 to 40 U mL−1 and a limit of detection of 0.07 U mL−1 using differential pulse voltammetry. In addition to detecting CA19-9 at clinically relevant concentrations for pancreatic cancer in standard solutions, the immunosensors provide the determination of CA19-9 on cell lysate and human serum samples. Using LbL films led to immunosensors with superior performance compared to similar systems obtained by drop casting. The fabrication of this relatively simple, inexpensive platform is a demonstration that SPCEs modified with cost-effective materials are able to detect cancer biomarkers and may be adapted to other disposable immunosensors.

We show here the design of a magnetoplasmonic sensing platform consisting of a bilayer of a transparent conducting oxide and a gold film grown on a ferromagnetic substrate. Near the bulk plasmon fr...

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Uma célula fotoeletroquímica (PEC) é um dispositivo capaz de oxidar matéria orgânica de resíduos industriais, armazenar energia solar em ligações químicas na forma de H2, bem como também gerar eletricidade de maneira limpa. Portanto, o uso desse sistema se torna altamente atraente como um potencial substituto para os combustíveis fósseis. No entanto, a eficiência da PEC é grandemente determinada pela fase cristalina do material envolvido, fator este que afeta diretamente as propriedades físico-químicas e, portanto, a viabilidade de aplicação. O objetivo do presente trabalho foi investigar a influência do pH da solução de deposição para filmes finos à base de óxido de bismuto-vanádio (BVO). Um fotocatalisador foi preparado por um método alternativo e, consequentemente, depositado no substrato de óxido de estanho e índio (ITO) pela técnica de deposição spin-coating utilizando três soluções que foram denominadas como M e A (com pH ≈ 2), e B (com pH ≈ 8). As propriedades microestruturais, analisadas por microscopia eletrônica de varredura, revelaram a formação de ilhas nanoporosas com morfologia esponjosa. A partir das propriedades estruturais, investigadas por difração de raios-X e espectroscopia Raman, foram confirmadas as fases cristalinas, ligações químicas atômicas e sua posição espacial na estrutura cristalina. Por outro lado, a energia de bandgap das fases cristalinas, obtida por espectroscopia de refletância difusa, mostrou valores entre 2,4 e 2,9 eV, significando que os filmes podem ser excitados por luz visível. O desempenho fotoeletroquímico dos eletrodos foi avaliado sob irradiação de luz, observando-se maior fotoatividade para o fotoeletrodo B, principalmente na região anódica, obtendo uma densidade de fotocorrente de +74,6 μA/cm2 a 1,23 VERH, cerca de 20 vezes maior em comparação aos eletrodos M e A. Esses resultados revelam propriedades fotoeletroquímicas promissoras para a heteroestrutura formada no eletrodo B, e sua aplicação em dispositivos fotoeletroquímicos para produção de energia renovável. A photoelectrochemical cell (PEC) is a device capable of oxidizing organic matter from industrial waste, solar energy storage in chemical bonds in the form of H2, as well as generating electricity in a clean manner. Therefore, the use of this system becomes highly attractive as a potential substitute for fossil fuels. However, the efficiency of a PEC is largely determined by the crystalline phase of the involved material, which directly affects the photochemical properties and, therefore the capability for applications. The objective of the present work is to investigate the influence of deposition solution pH on thin films based on bismuth-vanadate-oxide (BVO). A photocatalyst was prepared by an alternative method and therefore deposited on the indium tin oxide (ITO) substrate by the spin-coating deposition technique, using three solutions defined as: M and A (with pH ≈ 2) and B (with pH ≈ 8). The microstructural properties, analyzed by scanning electron microscopy, revealed the formation of nanoporous islands with spongy morphology. From the structural properties, investigated by X-ray diffraction and Raman spectroscopy, the crystalline phases, atomic chemical bonds and their spatial position in the crystal structure were confirmed. On the other hand, the bandgap energy of the crystalline phases, obtained by diffuse reflectance spectroscopy, was found to be between 2.4 and 2.9 eV, meaning that the films can be excited under visible light. The photoelectrochemical performance of the electrodes was evaluated under light irradiation, showing higher photoactivity for the B photoelectrode, mainly in the anodic region, obtaining a photocurrent density of +74.6 μA/cm2 at 1.23 VERH, about 20 times larger compared to the M and A electrodes. These results reveal promising photoelectrochemical properties for the heterostructure formed on the B electrode, and their potential application in photoelectrochemical devices for renewable energy production. Dissertação (Mestrado)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES We investigated thin films of P t/Co0,2T iO3,2/IT O and P t/Co2T i0,7O4−δ/IT O with different thicknesses using the magnetron sputtering technique, in order to evaluate its application potentials in memristors devices. We used characterizations by X–ray diffraction (XRD), X–ray reflectometry (XRR), Rutherford backscattering spectrometry (RBS), X–ray photoelectron spectroscopy (XPS), UV–VIS spectroscopy, electrical and magnetic analyzes. The systems with low crystallinity structure presented multifunctional performance revealing binary and analog resistive switching properties. The presence of oxygen vacancies confirmed by XPS and UV–VIS absorption are active agents in the electrical transport process of filamentary switching and adaptive conductance activity. Retention tests at high (HRS) and low (LRS) resistance regimes revealed a good ratio between resistive states, with magnitudes in the order of 104 and 106 . In addition, the existence of Co2+ and Co3+ ions provided a paramagnetic behavior at 300 K and weak ferrimagnetism at 5 K, as well as a magnetic effect capable of influencing the electrical response of the devices. Investigamos filmes finos de P t/Co0,2T iO3,2/IT O e P t/Co2T i0,7O4−δ/IT O com diferentes espessuras a partir da técnica de magnetron sputtering, com o objetivo de avaliar seus potenciais de aplicação em dispositivos memristors. Foram utilizadas caracterizações por difratometria de raios X (DRX), reflectometria de raios X (RRX), espectroscopia de retroespalhamento Rutherford (RBS), espectroscopia de fotoelétrons por raios X (XPS), espectroscopia UV–VIS, análises elétricas e magnéticas. Os sistemas com estrutura de baixa cristalinidade apresentaram desempenho multifuncional revelando propriedades de comutação resistiva binária e analógica. A presença de vacâncias de oxigênio confirmadas por XPS e absorção UV–VIS são agentes ativos no processo de transporte elétrico da comutação filamentar e na atividade adaptativa da condutância. Testes de retenção nos regimes de alta (HRS) e baixa (LRS) resistência revelaram uma boa razão entre os estados resistivos, com magnitudes na ordem de 104 e 106. Além disso, a existência de íons Co2+ e Co3+ proporcionaram um comportamento paramagnético em 300 K e fraco ferrimagnetismo em 5 K, assim como um efeito magnético capaz de influenciar na resposta elétrica dos dispositivos. São Cristóvão

Orthogonal fluxgates operated with a dc bias can achieve lower noise levels by suppressing Barkhausen jumps. We constructed and mathematically modeled a small orthogonal fluxgate consisting of a NiFe electroplated Cu wire, surrounded by a pick-up solenoid. A large dc current was applied through the wire to keep the core in constant saturation. This ensures that the main permeability modulation mechanism is magnetization rotation. Several output parameters were analyzed: sensitivity, noise and the perming error amplitude, all with respect to two input parameters, constant and alternating excitation field component. A good agreement between the experimental data and the theoretical model was found, with higher deviations appearing when the excitation field was not high enough to saturate the core and domain wall movement becomes relevant. Measured sensitivities were highly dependent on the excitation amplitudes, but mostly in the hundreds of V/T, and noise levels of about 0.75 nT in the 0.1–10 Hz range were found. As for the perming, the sensor zero readout can vary about 20 μT if subjected to magnetic shocks of up to 4.8 mT.

We report on immunosensors to detect D-dimer, a biomarker of venous thromboembolism, which are made with layer-by-layer (LbL) films containing immobilized anti-D-dimer monoclonal antibody alternated with a layer of chitosan/gold nanoparticles (AuNpChi). Detection was due to irreversible adsorption of the antigen D-dimer on its corresponding antibody according to a Langmuir-Freundlich model, thus giving rise to ellipsoidal structures in scanning electron microscopy images whose size and number increased with D-dimer concentration. The chemical groups involved in the adsorption process were inferred from polarization-modulated infrared reflection absorption (PM-IRRAS) through changes in the amide and carbonyl bands. Detection of D-dimer was made with electrical impedance spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The latter was the most sensitive with a detection limit of 9 × 10−4 µg/mL, sensitivity of 0.27 × 10−6 A/µgmL−1 with linear increase from 0 to 1 µg/mL. The selecti...

The electrical properties of poly(3-hexylthiophene) (P3HT) are very sensitive to the presence of oxygen, as well as in contact with several metals and oxides that are used as electrodes in organic devices. Such atoms and molecules have deleterious impact on the devices performance, normally causing the diminishing of their efficiency and operation lifetime. Therefore, understanding how those molecules, especially the oxygen, interact with the active layer is mandatory to prevent device degradation. Here we performed CELIV and dark Time-of-Flight measurements in a simplified diode structure ITO/P3HT/Ag before and after exposing the device to ambient air. The results analysis give evidence of a slow intake of oxygen molecules by diffusion, a deliberate filling of the generated oxygen traps by electrons and, consequently, a shift of the P3HT Fermi level toward the HOMO of P3HT. Finally the dynamics of hole extraction during CELIV measurements and their recovery are also discussed.

Nanoporous gold (NPG) films were electrodeposited on a gold substrate and the generated platform was used for amperometric determination of nitrite. The electrochemical characterization of different NPG surfaces showed that the electrocatalytic activity concerning the nitrite anodic oxidation is strongly modulated by changes in the electrodeposition parameters. Microstructural analysis using scanning electron microscopy, profilometry and X-ray diffraction revealed changes in the deposited layers, following a unique growth mechanism strongly dependent on applied potential and electrodeposition time. Accordingly, more negative potentials resulted in changes in morphology from highly branched standing flakes to flat dense surfaces, whereas higher electrodeposition times led to the evolution of nanodendrites. NPG electrodes prepared by electrodeposition at −4 V for 100 s were selected as the best platform for nitrite determinations at 0.77 V. Evaluation of sensing characteristics demonstrated the sensor exhibits a very fast response time (

Very few devices are capable to measure temperature with high precision and sensitive, mainly in the micro and nanoscale. It is known that for biological applications it is required high sensitivity devices in a short temperature range (288–323 K). Recent reports are proposing the use of ratiometric thermometers based in the luminescence of trivalent lanthanide ions. In this paper, the ratiometric thermometer characteristic was investigated in an alumino-phosphate glass doped with Eu2O3. The studied temperature range was 288 – 333 K, and the material presents high sensitivity values (1.25–1.68% per K). The luminescence of Eu3+-doped alumino-phosphate glass does no present losses by energy transfer mechanism in this temperature range, making a quick predicable thermometric parameter by use of ratio between the integrated intensities of 5D0 → 7F2 and 5D0 → 7F0 transitions, respectively. Both excitation and emission are in wavelengths not strongly absorbed by living tissues, becoming promising material to applications in the laboratories scale, as the temperature measurements of cell cultures, and monitoring of tissues that does not require high penetration of excitation wavelengths.

In this study, we show the synthesis of novel hybrid organic-inorganic aerogel materials with one-dimensionally aligned pores and demonstrate their use as sustained and prolonged release systems for a hydrophobic drug. The materials are synthesized by trapping mesoporous silica nanoparticles within a hyperbranched polymer network made from poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA). The synthetic method involves dispersing mesoporous silica nanoparticles in a polymer solution, then freeze-drying the solution, and finally subjecting the resulting materials to high temperature to activate a solid-state condensation reaction between PVA and PAA. Before trapping the mesoporous silica nanoparticles within the hyperbranched polymeric network, their pores are decorated with hydrophobic groups so that they can serve as good host materials for hydrophobic drugs. The potential application of the hybrid aerogels as drug carriers is demonstrated using the hydrophobic, anti-inflammatory agent dexamethasone (DEX) as a model drug. Due to their hydrophobic pores, the hybrid aerogels show excellent drug loading capacity for DEX, with an encapsulation efficiency higher than 75%. Furthermore, the release pattern of the payloads of DEX encapsulated in the aerogels is highly tailorable (i.e., it can be made faster or slower, as needed) simply by varying the PVA-to-PAA weight ratio in the precursors, and thus the 3-dimensional (3-D) structures of the cross-linked polymers in them. The materials also show sustained drug release, for over 50 days or more. In addition, the aerogels are biocompatible, as demonstrated with Vero cells, and greatly promote the cell proliferation of L929 fibroblasts. Also, the nanoparticles functionalized with quaternary groups and dispersed within the aerogels display bactericidal activity against E. coli, S. aureus, B. subtilis, and P. aeruginosa. These new hybrid aerogels can, thus, be highly appealing biomaterials for sustained and prolonged drug release, such as wound dressing systems.

Neste trabalho, foram depositados filmes finos de nitreto de zirconio sobre substratos de carbono e silicio. O nitreto de zirconio ocupa lugar de destaque como revestimento, pois possui dureza elevada, estabilidade quimica e termica admiraveis, alem de possuir baixa resistividade eletrica. Devido a essas caracteristicas, o mesmo vem sendo amplamente aplicado como revestimento decorativo e protetor, sendo tambem utilizado em implantes e outros artefatos medicos devido a sua biocompatibilidade. O objetivo principal desse estudo e realizar a caracterizacao fisico-quimica dos filmes finos de ZrN utilizando uma tensao de BIAS para aumentar a densidade dos mesmos, a fim de evitar a incorporacao de contaminantes. Os resultados obtidos por RBS mostram que os filmes sao estequiometricos (condicao na qual possuem as melhores propriedades tribologicas) e possuem baixa quantidade de inclusao de impurezas, o que os caracteriza como sendo de boa qualidade. Alem disso, a analise por espectroscopia Raman comprova a formacao efetiva do nitreto de zirconio, e sua dureza de 15,15 GPa medida por nanoindentacao encontra-se de acordo com os valores encontrados na literatura. http://dx.doi.org/10.18226/23185279.v6iss1p11

Integrated circuits currently use mainly copper as the interconnect material; unfortunately the ongoing miniaturization currently requires materials with higher electromigration resistance and possibly improved conductivity. In this context we report on the structure, microstructure and electrical properties of a series of Cu-Ge(O) alloy films, electrodeposited from an alkaline tartrate electrolyte. The composition of the films varies between zero and 20 at% Ge, with a significant incorporation of oxygen. Film morphology is dense and uniform, with Cu-Ge films exhibiting smaller apparent grain size (~50 nm) with respect to Cu films grown from a similar electrolyte. Solid solutions and phase mixtures of a solid solution with the intermetallic are observed with increasing Ge fraction; the presence of intermetallic phases is confirmed by TEM imaging and diffraction. The resistivity of 50 nm thick films follows the published trend, with a slight increase of the value upon solid solution formation and a minimum in correspondence of the intermetallic composition. Thicker films (~1 um) on the other hand show a different trend, with resistivity increasing with Ge and O at%; in this case the resistivity is probably dominated by the oxygen incorporation.

This paper presents a study on the incubation effect during fs-laser micromachining of gallium nitride films with three different wavelengths (1030, 515 and 343 nm) by varying the number of laser pulses applied per sample surface area and measuring the damage threshold fluence using the zero damage method. As we implemented the exponential defect accumulation model to the experimental incubation data, we determined the value of the incubation parameter of (0.02 ± 0.01) for 1030 nm, (0.07 ± 0.01) for 515 nm and (0.4 ± 0.1) for 343 nm. This shows that for excitation in the green and infrared spectral region, GaN requires approximately 100 overlapping pulses in order for the incubation to take place while, for ultraviolet excitation, the incubation was achieved faster, with the overlap of about 10 pulses. Furthermore, we compared our data for the single pulse damage threshold with a theoretical model that takes into account multiphoton and avalanche ionization. Our results indicate that at 343 nm and 515 nm, micromachining is dominated by multiphoton ionization, while at 1030 nm other effects, such as tunneling ionization, must also be contributing. Finally, we believe this paper brings relevant information on the fs-laser micromachining of GaN.

Barium titanate (BaTiO3) thin films were grown on Au/Si:B (111) substrates using an electron beam physical vapor deposition (EB-PVD) method. Investigation was made of the effects of grain size and strain on the temperature-dependent optical properties of these thin films, controlled using post-deposition annealing treatments at 400 °C and 550 °C. The structural, morphological, and optical properties of the deposited films were studied by X-ray diffraction (XRD), atomic force microscopy (AFM), and luminescence spectroscopy, respectively. The XRD and AFM analyses revealed the tetragonal crystal structure of the films. The luminescence spectra properties were attributed to recombination of the self-trapped excitons that formed localized states in the forbidden gaps (produced by impurities and oxygen vacancies), modulated by thermal treatment and the presence of oxygen. With increasing thickness, the blue and violet emission energies increased from 2.60 to 2.66 eV, and from 2.82 to 2.90 eV, respectively. This work shows that extrinsic and intrinsic defects can induce and enhance luminescence.

Electronic tongues (e-tongues) are promising analytical devices for a variety of applications to address the challenges of quality control in water monitoring and industries of foods, beverages, and pharmaceuticals. A crucial drawback in the current e-tongues is the need to recalibrate the device when one or more sensing units (usually with modified surface) are replaced. Another downside is the necessity to perform subsequent surface modifications and analyses to each of the diverse sensing units, undermining the simplicity and velocity of the method. These features have prevented widespread commercial use of the e-tongues. In this paper, we introduce a microfluidic e-tongue that overcomes all such limitations. The key principle of global selectivity of the e-tongue was achieved by recording only a single response, namely, the equivalent admittance spectrum of an association of resistors in parallel. Such resistors consisted of five nonfunctionalized stainless steel microwires (sensing units), which were short-circuited and coated with gold, platinum, nickel, iron, and aluminum oxide films. The microwires were inserted in a chip composed of a single piece of polydimethylsiloxane (PDMS). Using impedance spectroscopy, the e-tongue was successfully applied in classification of basic tastes at a concentration below the threshold for the human tongue. In addition, our chip allowed the distinction of various chemicals used in oil industry. Finally, our cleanroom-free prototyping allows the mass production of chips with easily replaceable and reproducible sensing units. Hence, one can now envisage the widespread dissemination of e-tongues with fast and reproducible data.

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Substratos SERS baseados em filmes finos de nanopartículas metálicas de ouro e prata dispersas em óleo de mamona foram utilizados para caracterização da adsorção de moléculas de agrotóxicos. Foram analisadas as adsorções nas superfícies metálicas de ouro e prata de três agrotóxicos: 2,4-D, Diuron e Tebuconazol Os filmes finos obtidos a partir das nanopartículas plasmônicas de Au e Ag dispersas em óleo de mamona permitiram a identificação da adsorção de moléculas de agrotóxicos pela espectroscopia por espalhamento Raman intensificado por superfície (SERS) que possui capacidade de detectar moléculas em concentrações de, aproximadamente, partes por milhão de unidades com mais eficiência quando comparada à técnica convencional de espectroscopia Raman. As atribuições de bandas para os agrotóxicos 2,4-D, Diuron e Tebuconazol foram feitas pela análise dos espectros SERS obtidos. Foi possível verificar que o sítio molecular envolvido na adsorção do agrotóxico 2,4-D sobre a superfície metálica é o grupo carboxilato, com o anel fenílico próximo a uma posição perpendicular à sua superfície. As atribuições do espectro SERS do Diuron permitiram inferir que os dois grupos de nitrogênio presentes nas moléculas são os sítios de interação com a superfície da nanopartícula de ouro. Já para o agrotóxico Tebuconazol, a intensificação das bandas SERS atribuídas aos modos normais do grupo triazol, permitiram afirmar que a interação com a superfície do metal ocorre por esse grupo funcional. O estudo das interações das moléculas de agrotóxicos com as nanopartículas metálicas em diferentes substratos permitiu determinar as condições mais favoráveis para a ocorrência de adsorção. Portanto, o filme fino obtido pela dissolução do analito na suspensão utilizada na deposição das nanopartículas foi o meio mais adequado para a obtenção dos espectros SERS dos agrotóxicos, indicando que a solubilidade no meio hidrofóbico favoreceu a adsorção na superfície metálica. Os grupos hidroxila, presentes na estrutura do triacilglicerol do óleo de mamona, mostraram-se agentes efetivos na formação e estabilização das nanopartículas metálicas sintetizadas e favoreceram a interação das moléculas de agrotóxicos em experimentos com filmes finos. SERS substrates based on thin films from metallic gold and silver nanoparticles dispersed in castor oil were used for the characterization of the adsorption of pesticide molecules. The adsorption on the gold and silver metallic surfaces of three pesticides was analyzed: 2,4-D, Diuron and Tebuconazole. The thin films obtained from the plasmonic Au and Ag nanoparticles dispersed in castor oil allow the identification of the adsorption of pesticide molecules by surface enhanced Raman scattering (SERS) spectroscopy which technique has the capability of detecting molecules in concentrations of approximately parts per million units, when compared with the conventional Raman spectroscopy technique. The band assignments for the pesticides 2,4-D, Diuron and Tebuconazole were made by the analysis of the recorded SERS spectra. It was possible to verify that the molecular site involved in the adsorption of the 2,4-D pesticide on the metallic surface is the carboxylate group, with the phenyl ring close to a position perpendicular to its surface. The assignment to Diuron's SERS spectrum allowed us to infer that the two nitrogen groups present in the molecules are the sites of interaction with the surface of gold nanoparticle. On the other hand, for the Tebuconazole pesticide the intensification of SERS bands attributed to the normal modes of the triazole group, allows to affirm the interaction with the metal surface occurs by this functional group. The study of the interactions of pesticide molecules with the metallic nanoparticles in different substrates allowed the determination of the most favorable conditions for the occurrence of adsorption. Therefore, the thin film obtained by the dissolution of the analites in the suspension used for the deposition of the nanoparticles was the most suitable medium for obtaining the SERS spectra of the pesticides indicating that the solubility in the hydrophobic medium favored adsorption on the metal surface. The hydroxyl groups, present in the structure of the castor oil triacylglycerol, proved to be effective agents in the formation and stabilization of the synthesized metallic nanoparticles and favored the interaction of pesticide molecules in experiments with thin films.

Na primeira parte desse trabalho, investigamos a estabilidade de skyrmions constituı́dos de dois merons (skyrmions 2) no modelo de Heisenberg 2 via integração das equa- ções de movimento para cada spin. O estudo se deu na rede antiferromagnética ( ). A influência de um campo magnético e de impurezas não magnéticas na dinâmica desses sólitons também foram investigadas. Nossos resultados indicam que os skyrmions de dois núcleos na rede são mais instáveis do que os seus contrapares ferromagnéticos e que estes, ao contrário do que se observa na rede , não possuem um movimento de rotação ao redor de seu centro. Também obtivemos que skyrmions 2 são atraı́dos por impurezas magnéticas e colapsam ao atingi-la, semelhante ao que ocorre na rede ferromagnética. A aplicação de um campo magnético também influenciou na sua dinâmica com a deformação da textura em um skyrmion do tipo 1. Já na segunda parte do trabalho estudamos via método de Monte Carlo o modelo de Heisenberg dipolar bidimensional (2), conside- rando a constante dipolar = 0.2. Técnicas como repesagem de histogramas e o método de Ewald foram empregados para melhor eficiência da simulação, reduzindo o custo com- putacional. Como previsto teoricamente, uma fase ferromagnética planar foi estabilizada a baixas temperaturas. A transição para o estado ordenado se deu a uma temperatura crı́tica de = 0.975 ± 0.010, resultado estimado pela análise de escala de tamanho finito ( ). Além disso, pela estimamos os seguintes expoentes crı́ticos para a transição: = 1.21(3), = 2.09(5), = 0.184(6), e = −0.44(2). Esses valores estão próximos dos encontrados para modelos dipolares semelhantes, embora haja uma pequena discrepância com o resultado obtido para modelo dipolar. Levantamos a hipótese de que essa dis- crepância possa ter origem na anisotropia quadripolar da interação dipolar assim como se observa nos modelos dipolares puros. Também observamos que o expoente do modelo 2 se encontra na janela de universalidade do modelo quadripolar ℎ 4 , sugerindo que sistemas dipolares possam pertencer à universalidade ℎ 4 . Palavras-chave: Skyrmions. Merons. Modelo de Heisenberg. Interação dipolar. In the first part of this work, we investigated the stability of two merons skyrmions (skyr- mions 2) in the Heisenberg 2 model by integrating the equations of motion for each spin. The study took place in the antiferromagnetic lattice ( ). The influence of a magnetic field and non-magnetic impurities on the dynamics of these solitons were also in- vestigated. Our results indicate that the two-core skyrmions in the lattice are more unstable than their ferromagnetic counterparts and that, unlike the lattice, they do not rotate around their center. We also found that 2 skyrmions are attracted by mag- netic impurities and when one of the cores falls into the vacancy, the 2 collapses com- pletely, similar to what occurs in the ferromagnetic lattice. The application of a magnetic field also influenced its dynamics with texture deformation in a 1 skyrmion. Already in the second part of the work we studied via Monte Carlo method the two-dimensional di- polar Heisenberg model (2), considering the dipolar constant = 0.2. Techniques such as histogram re-weighing and the Ewald method were employed for better simulation efficiency, reducing the computational cost. Just as in theoretically predicted, a planar fer- romagnetic phase was stabilized at low temperatures. The transition to the ordered state took place at a critical temperature of = 0.975±0.010, the result estimated by finite size scale analysis ( ). In addition, by we estimate the following critical exponents for the transition: = 1.21(3), = 2.09(5), = 0.184(6) and = −0.44(2). These values are close to those found for similar dipolar models, although there is a slight discrepancy with the result obtained for dipolar model. We hypothesized that this discrepancy may originate from the quadripolar anisotropy of dipolar interaction as observed in pure dipolar models. We also note that the exponent of the 2 model falls into the uni- versality window of the quadripolar model ℎ 4 , suggesting that dipolar systems may belong to the ℎ 4 universality. Keywords: Skyrmions. Merons. Heisenberg model. Dipolar interaction.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Molybdenum disulfide (MoS2) has been of interest to the scientific and industrial community due to its excellent physical and chemical characteristics and possible applications in various areas such as nanoelectronics, biotechnology and polymeric compounds. In this research project, liquid phase exfoliation (LPF) in aquous media was used to prepare two-dimensional MoS2 particles and later use in the production of two-dimensional nanocomposites, as it is an extremely attractive option, low cost and environmentally friendly option. It has been found by different techniques (Scanning Electron Microscopy - SEM, Atomic Force Microscopy – AFM, Raman Spectroscopy, UV-VIS Spectroscopy, Optical Microscopy, Zeta Potential, Dinamic Light Scattering – DLS and Infrared Spectroscopy with Fourier Transform Infrared –FTIR) that water is an excellent solvent for producing few layers MoS2, generating a dispersion with excellent stability. Through quantic ab initio simulations based on density functional theory (DFT) it could be inferred that this stability is due to the functionalization of the sulfur edges “S” with hydrogen “H”. In a first step, polystyrene - PS was used as a polymeric matrix in the production of MoS2 nanocomposites, using a double screw extruder as a component blending medium. Several characterization techniques were used to evaluate the nanocomposites produced, such as: Size Exclusion Chromatography - SEC, Fourier Transform Infrared – FTIR, Raman Spectroscopy, X-ray Diffraction –XRD, Contact Angle – AC, Scanning Electron Microscopy – SEM, X-ray Microtomography, Thermogravimetric Analysis – TGA, Dynamic Mechanical Analysis – DMA, Tensile test and Reological test. Nanocomposites showed increased toughness when compared to pure PS (especially with a load content of 0.002 wt% by mass), but also led to positive changes in thermal stability, thereby preventing thermal degradation of PS during processing. The results obtained also indicated that the load was homogeneously dispersed and with good adhesion to the polymeric matrix. Subsequently, a study was performed using a biodegradable polymer matrix, the Poly (butylene adipate-co-terephthalate) – PBAT. This is considered one of the most promising polymers for the production of sustainable film packaging. Thus, films were obtained by extrusion of PBAT incorporating 0.001, 0.002 and 0.003 wt% by mass of MoS2. The different compositions obtained in the form of films were characterized by XRD, FTIR and by mechanical tensile test in the longitudinal and transversal directions. The XRD analyzes showed that the crystalline phases present in PBAT did not show significant changes with the addition of MoS2. The mechanical properties of PBAT/MoS2 nanocomposites showed better performance in the longitudinal direction. These results showed that the two-dimensional structure of this load with a low number of layers (~ 5) managed to provide excellent properties to the polymeric matrix of PS and PBAT, even at extremely low levels never before presented in the literature. O dissulfeto de molibdênio (MoS2) tem despertado interesse na comunidade científica e industrial devido a suas excelentes propriedades físico-químicas e possíveis aplicações em diversas áreas, tais como: nanoeletrônica, biotecnologia e compósitos poliméricos. Nessse projeto de pesquisa, a esfoliação em fase líquida (EFL) em meio aquoso foi utilizada para a preparação de partículas bidimensionais de MoS2 e posterior utilização na produção de nanocompósitos, por ser uma opção extremamente atraente, de baixo custo e ambientalmente amigável. Verificou-se por diferentes técnicas (Microscopia Eletrônica de Varredura - MEV, Microscopia de Força Atômica - AFM, Espectroscopia de Raman, Espectroscopia UV-VIS, Microscopia Ótica, Potencial Zeta, Espalhamento de Luz e Espectroscopia no infravermelho com transformada de Fourier – FTIR) que a água é um excelente solvente para produção de MoS2 com poucas camadas, gerando uma dispersão com excelente estabilidade. Através de simulações quânticas ab initio baseadas na teoria do funcional da densidade (DFT), pôde-se inferir que essa estabilidade se deve a funcionalização das bordas de enxofre “S” com hidrogênio “H”. Em uma primeira etapa, utilizou-se o poliestireno (PS) como matriz polimérica na produção dos nanocompósitos com MoS2, empregando uma extrusora dupla rosca como meio de mistura dos componentes. Diversas técnicas de caracterização foram utilizadas para avaliação dos nanocompósitos produzidos, como: Cromatografia por exclusão de tamanho (SEC), Espectroscopia no infravermelho com transformada de Fourier (FTIR), Microscopia Confocal Raman, Difração de Raios X (DRX), Ângulo de contato (AC), Microscopia Eletrônica de Varredura (MEV), Microtomografia de Raios X, Análise Termogravimétrica (TGA), Análise Dinâmico-Mecânica (DMA), Ensaios de Tração e Ensaios Reológicos. Os nanocompósitos apresentaram aumento da tenacidade quando comparados ao PS puro (especialmente com teor de carga de 0,002% em massa), como também conduziram a alterações positivas na estabilidade térmica, evitando com isso a degradação térmica do PS durante o processamento. Os resultados obtidos também indicaram que a carga foi homogeneamente dispersa e com boa adesão a matriz polimérica. Posteriormente foi realizado um estudo empregando uma matriz polimérica biodegradável, o poli (butileno adipato-co-tereftalato) – (PBAT). Esse é considerado um dos polímeros mais promissores para a produção de embalagens de filmes sustentáveis. Dessa forma, foram obtidos filmes por extrusão plana de PBAT incorporando 0,001, 0,002 e 0,003% em massa de MoS2. As diferentes composições obtidas na forma de filmes foram caracterizadas por DRX, FTIR e por ensaio mecânico de tração no sentido longitudinal e transversal. As análises de DRX mostraram que as fases cristalinas presentes no PBAT não apresentaram mudanças significativas com a adição do MoS2. As propriedades mecânicas dos nanocompósitos de PBAT/MoS2 apresentaram melhor desempenho no sentido longitudinal. Esses resultados evidenciaram que a estrutura bidimensional dessa carga com baixo número de camdas (~5) conseguiu proporcionar excelentes propriedades as matriz poliméricas de PS e PBAT, mesmo em teores extremamente baixos até então nunca apresentados na literatura.

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No. of bitstreams: 1 reis_sp_dr_ilha.pdf: 39809984 bytes, checksum: e88521c8a7b4db40c8da4212ae2672a4 (MD5) Previous issue date: 2020-01-31 Approved for entry into archive by Raiane da Silva Santos (raiane.santos@unesp.br) on 2020-03-20T13:27:39Z (GMT) No. of bitstreams: 1 reis_sp_dr_ilha.pdf: 39809984 bytes, checksum: e88521c8a7b4db40c8da4212ae2672a4 (MD5) Submitted by SAULO PORTES DOS REIS (spdreis@ifsp.edu.br) on 2020-03-19T19:34:26Z No. of bitstreams: 1 Um estudo da influência de defeitos sobre a relaxação dielétrica e outras propriedades físicas relacionadas de filmes finos de BiFeO3 .pdf: 39809984 bytes, checksum: e88521c8a7b4db40c8da4212ae2672a4 (MD5) Made available in DSpace on 2020-03-20T13:27:39Z (GMT). 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No. of bitstreams: 1 reis_sp_dr_ilha.pdf: 39809984 bytes, checksum: e88521c8a7b4db40c8da4212ae2672a4 (MD5) Previous issue date: 2020-01-31 Approved for entry into archive by Raiane da Silva Santos (raiane.santos@unesp.br) on 2020-03-20T13:27:39Z (GMT) No. of bitstreams: 1 reis_sp_dr_ilha.pdf: 39809984 bytes, checksum: e88521c8a7b4db40c8da4212ae2672a4 (MD5) Made available in DSpace on 2020-03-20T13:27:39Z (GMT). No. of bitstreams: 1 reis_sp_dr_ilha.pdf: 39809984 bytes, checksum: e88521c8a7b4db40c8da4212ae2672a4 (MD5) Previous issue date: 2020-01-31 Approved for entry into archive by Raiane da Silva Santos (raiane.santos@unesp.br) on 2020-03-20T13:27:39Z (GMT) No. of bitstreams: 1 reis_sp_dr_ilha.pdf: 39809984 bytes, checksum: e88521c8a7b4db40c8da4212ae2672a4 (MD5) Made available in DSpace on 2020-03-20T13:27:39Z (GMT). No. of bitstreams: 1 reis_sp_dr_ilha.pdf: 39809984 bytes, checksum: e88521c8a7b4db40c8da4212ae2672a4 (MD5) Previous issue date: 2020-01-31 Made available in DSpace on 2020-03-20T13:27:39Z (GMT). No. of bitstreams: 1 reis_sp_dr_ilha.pdf: 39809984 bytes, checksum: e88521c8a7b4db40c8da4212ae2672a4 (MD5) Previous issue date: 2020-01-31 Approved for entry into archive by Raiane da Silva Santos (raiane.santos@unesp.br) on 2020-03-20T13:27:39Z (GMT) No. of bitstreams: 1 reis_sp_dr_ilha.pdf: 39809984 bytes, checksum: e88521c8a7b4db40c8da4212ae2672a4 (MD5) Made available in DSpace on 2020-03-20T13:27:39Z (GMT). No. of bitstreams: 1 reis_sp_dr_ilha.pdf: 39809984 bytes, checksum: e88521c8a7b4db40c8da4212ae2672a4 (MD5) Previous issue date: 2020-01-31 Made available in DSpace on 2020-03-20T13:27:39Z (GMT). No. of bitstreams: 1 reis_sp_dr_ilha.pdf: 39809984 bytes, checksum: e88521c8a7b4db40c8da4212ae2672a4 (MD5) Previous issue date: 2020-01-31 Este trabalho relata o impacto de defeitos nas propriedades elétricas de filmes finos de \BF, com diferentes defeitos introduzidos durante a síntese. As fases secundárias e as vacâncias de oxigênio foram os defeitos mais aparentes em comparação aos filmes monofásicos. As propriedades estruturais foram analisadas por difração de raios X, espectroscopia Raman, microscopia de piezo-resposta (PFM) e espectroscopia de fotoelétrons excitados por raios-X (XPS). As propriedades elétricas dos filmes foram estudadas em termos de relaxação dielétrica, condutividade elétrica e condutividade local através de grãos e contornos de grãos. Para fazer isso, foi feita uma descrição completa do formalismo da impedância. No processo termicamente ativado, as energias de ativação da relaxação e condução dielétrica foram muito semelhantes para os filmes com fases secundárias. Por outro lado, a energia de ativação da condução aumenta para o filme monofásico tratado em atmosfera de oxigênio. Essas energias de ativação foram atribuídas às primeira e segunda ionização de vacâncias de oxigênio. O controle de defeitos durante a síntese dos filmes mostrou-se útil para controlar a condutividade elétrica e outros parâmetros relacionados aos filmes finos de BiFeO3. This work reports the impact of defects on the electrical properties of BiFeO3 thin films with different defects introduced during the synthesis. Secondary phases and oxygen vacancies were the most apparent defects compared to single-phase films. The structural properties were analyzed by X-ray diffraction, Raman spectroscopy, piezoresponse force microscopy (PFM) and X-ray photoelectron spectroscopy (XPS). The electrical properties of the films were studied in terms of dielectric relaxation, electrical conductivity and local conductivity through grain and grain boundaries. To do this, a thorough description of the impedance formalism was made. From thermally activated process, the activation energies of dielectric relaxation and conduction were very similar for films with secondary phases. On the other hand, the activation energy of conduction increases for single-phase film post annealed in oxygen atmosphere. These activation energies were attributed to the first and second ionization oxygen vacancies. The control of defects during the synthesis of the films was shown to be useful to control the electrical conductivity and other parameters related to the thin films of BiFeO3.

Agradecimentos: This work was supported by the Sao Paulo Research Foundation (FAPESP), grants #2019/18460–4 and #2018/24461–0, FAPERGS, grants #17/2551-0001052-3 and #19/2551-0002288-3, and CNPq, grant #422372/2016–1. FC is FAPESP fellow. MJMJ and LML are CAPES fellows. CAF and FA are CNPq fellows. The authors would like to thank the technician R.B. Merlo for the annealing experiments execution and R. Marcon for his help in XRD treatment data. Abstract: The vast, unexplored chemical realm of multi-principal element alloys (MPEAs) has encouraged researchers to design and synthetize advanced materials based on refractory metals, metalloids, and deoxidizer elements, that are expected to follow single-phase, solid solution high-entropy alloys (HEAs)’ footsteps. In this paper, we have theoretically and experimentally studied the AlSiTaTiZr alloy in the thin film form, due to potential applications as a high-temperature oxidation-resistant coating. The MPEA film, synthetized by radio-frequency magnetron sputtering (RFMS), shows a considerable glass-forming ability. However, the metallic glass structure transits to several intermetallic compound phases by post-thermal annealing at ~873 K, confirming that both thermodynamics and kinetics determine the formation of phases in sputtered MPEAs. Moreover, a strong tendency of Si and Al to form compounds with transition metals was revealed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermodynamic investigations. Special focus is given to the role played by both entropy and enthalpy on the phase evolution, demonstrated by thermodynamic calculations using the regular solution model and the CALculation of PHAse Diagrams (CALPHAD) method. This methodology is presented as a useful approach for starting deeper thermodynamic investigations in the thin film literature of MPEAs and HEAs, currently focused on the ultimate properties of such alloys FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DO RIO GRANDE DO SUL - FAPERGS CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Fechado

Orientador: Prof. Dr. Aldo J. G. Zarbin Coorientadora: Prof.a Dr.a Elisa S. Orth Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Química. Defesa : Curitiba, 19/02/2020 Inclui referências: p. 129-146 Área de concentração: Química Inorgânica Resumo: O fósforo negro (BP, do inglês black phosphorus) é um material versátil e promissor para as mais diversas áreas, com destaque para a de energia (i.e. eletrodos de baterias). Sua elevada instabilidade quando exposto a condições ambientes, entretanto, acaba limitando severamente sua manipulação e consequente aplicação. Nesse trabalho, apresentamos um estudo sistemático realizado para obtenção de materiais estáveis baseados em BP através da síntese de compósitos com polianilina (PANI). Os filmes finos de BP-PANI foram sintetizados pelo método interfacial líquido/líquido (L/L), que se baseou inicialmente na polimerização da anilina em uma dispersão desaerada de BP (em acetonitrila). Para isso, o BP foi esfoliado em banho de ultrassom através de diferentes metodologias, levando à obtenção de quatro compósitos, obtidos autossustentados diretamente na interface L/L (solução ácida/tolueno) após uma etapa de troca de solventes. A caracterização desses materiais mostrou que o BP auxilia na prevenção da reticulação das cadeias da PANI, tornando os compósitos, em geral, mais polarônicos (i.e. condutores). Em seguida, os filmes foram expostos a condições ambientes e monitorados por técnicas espectro e microscópicas. Os resultados mostraram que o início da degradação do BP desprotegido se deu com apenas 3 dias, enquanto que, quando na presença de PANI, os indícios de degradação ocorreram após 60 dias para o melhor compósito, indicando um aumento de quase 1500% na estabilidade do material. Após atestar a efetiva proteção do BP pela PANI, os materiais foram avaliados com relação à sua resposta e estabilidade eletroquímica, visando investigar suas propriedades de armazenamento de energia. Nesse caso, a avaliação foi realizada tanto sob atmosfera inerte (fluxo de N2(g)) quanto em condições ambientes. Todos os materiais foram caracterizados por microscopia eletrônica de varredura e espectroscopia Raman antes e após o estudo. Os resultados mostraram o mesmo comportamento para os filmes BP-PANI na presença e na ausência da purga de N2(g), evidenciando a integridade do material quando recoberto pelo polímero. Voltametrias cíclicas e medidas de carga e descarga (CD) foram conduzidas em NaCl, com o objetivo de atestar a possibilidade do uso dos compósitos como eletrodos de baterias aquosas de Na+. A preservação do BP foi atestada no filme de BP-PANI mesmo após 200 ciclos voltamétricos. O BP isolado, entretanto, foi degradado logo após o primeiro ciclo voltamétrico, evidenciando a baixa estabilidade química e eletroquímica do material. As curvas de CD mostraram elevados valores de capacidade específica, atingindo cerca de 200 mA h g-1, e alta estabilidade, com uma eficiência coulômbica de 100%. Considerando-se que esses resultados foram obtidos a partir da exposição do BP aos ambientes mais nocivos à sua integridade (água com O2(g) dissolvido), esse trabalho mostra-se ainda mais relevante. Dessa forma, apresentamos estratégias eficientes para aumentar a estabilidade do BP e atestamos a possibilidade de superar os limites envolvendo as suas reais aplicações. Abstract: Black phosphorus (BP) is a versatile and promising material in several areas, especially in the energy field (i.e. electrodes for batteries). Its high instability when exposed to ambient conditions, however, severely limits its manipulation and further application. In this work, we present a systematic study performed in order to obtain stable BP-based materials through the synthesis of composites with polyaniline (PANI). Thin films of BP-PANI were synthesized through the interfacial liquid/liquid (L/L) method, initially based on the aniline polymerization in a deaerated dispersion of BP (in acetonitrile). For this purpose, BP was exfoliated in ultrasound bath through different methodologies, leading to four composites, obtained self-sustaining directly at the L/L interface (acid solution/toluene) after a step of solvent exchange. The characterization of these materials showed that BP assists to prevent crosslinking of PANI chains, generally, leading to more polaronic composites (i.e. conductive). In the following, the films were exposed to ambient conditions and monitored through spectro and microscopic techniques. Results showed that the unprotected BP started to degrade within 3 days, while when in the presence of PANI, degradation evidences started after 60 days of exposition to the best composite, indicating an increase of up to 1500% in the material stability. After attesting the effective protection of BP by PANI, materials were evaluated regarding their electrochemical response and stability, aiming to investigate storage energy properties. In this case, the evaluation was performed both under inert atmosphere (N2(g) flow) and ambient conditions. All materials were characterized by scanning electron microscopy and Raman spectroscopy before and after the studies. Results displayed the same behaviour for BP-PANI films in the presence and the absence of N2(g) purge, evidencing the integrity of covered BP. Cyclic voltammetry and charge-discharge (CD) measurements were carried out in NaCl, targeting employing the composites as electrodes for Na+ aqueous batteries. BP preservation was attested in the BP-PANI film even after 200 voltammetric cycles. Bare BP, however, degraded soon after the first cycle, evidencing its low chemical and electrochemical stability. CD curves showed high values of specific capacity, reaching up to 200 mA h g-1, and great stability, with a coulombic efficiency of 100%. Considering that these results were obtained when exposing BP to its most harmful environments (oxygenated water), this work shows to be even more relevant. In this sense, we presented efficient strategies to increase BP stability and certified the possibility of overcoming the limits regarding its real applications.

Orientadores: Marisa Masumi Beppu, Hernandes Faustino de Carvalho Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química Resumo: O câncer de próstata (CaP) é uma neoplasia silenciosa que possui, quando diagnosticado em suas fases iniciais, grandes chances de cura. Dessa forma, a busca por métodos de detecção de células tumorais circulantes (CTCs) e de marcadores prognósticos para o CaP é necessária a fim de reduzir sua crescente taxa de mortalidade entre os homens. Para fins biomédicos, o desenvolvimento de superfícies que permitam a interação com células tumorais e o controle da adesão celular é, sem dúvidas, um grande desafio na Ciência dos Materiais. A técnica layer-by-layer (LbL) se destaca nesse contexto como uma ferramenta eficiente de funcionalização de superfícies, em virtude do controle rigoroso sobre a funcionalidade, composição e propriedades dos materiais que produz. Neste estudo, foram desenvolvidos filmes LbL compostos de quitosana (CHI) e ácido hialurônico (HA) a fim de capturar CTCs, explorando a interação específica HA-CD44. O CD44 é uma glicoproteína extracelular envolvida em múltiplos processos celulares, entre eles a adesão celular, tendo como seu principal ligante o HA. Aqui, foi investigada a influência de propriedades físico-químicas de filmes HA/CHI, controladas pelas condições de montagem (pH e força iônica das soluções poliméricas, grau de desacetilação da quitosana e número de bicamadas depositadas), nos seus potenciais de captura de células tumorais prostáticas (linhagem PC3). Sugere-se que superfícies menos rugosas, com menor mobilidade de carga e com concentrações médias a baixas de HA induzem a adesão de células tumorais. Também foi investigada a funcionalização dos filmes HA/CHI com aglutinina de gérmen de trigo (WGA) e quitosana sulfatada (ChiS), que se mostraram estratégias eficazes para, respectivamente, aumentar o potencial de interação célula-substrato e conferir propriedades antitrombogênicas aos filmes. Além disso, eletrodos interdigitados foram recobertos com multicamadas de HA/CHI, apresentando significativa capacidade de detecção de células tumorais a partir de medidas de impedância elétrica, validada pelo uso de mapas de visualização. Em suma, este estudo destaca os filmes HA/CHI como plataformas promissoras para a captura de CTCs, apontando seu uso em aplicações diversas, tais como sensoriamento, mecanismos rápidos de diagnóstico e cascatas de sinalização celular Abstract: Prostate cancer is a silent neoplasm that has higher chances of cure if detected in early stages. Thus, it is necessary to develop methods for the detection of circulating tumor cells (CTCs), and also to improve the prognostic markers of prostate cancer in order to reduce its increasing mortality rate among men. For biomedical purposes, the development of surfaces that provide the interaction with tumor cells, and the control of cell adhesion is a major challenge in materials science. In this scenario, the Layer-by-layer (LbL) technique stands out as a promising method for surface functionalization, due to its precise control over the materials functionality, composition and properties. In this study, LbL films based on chitosan (CHI) and hyaluronan (HA) were developed aiming to capture CTCs, exploring the specific interaction HA-CD44. CD44 is an extracellular glycoprotein involved in multiple cellular processes, including cell adhesion, and has a specific binding domain for HA. This study explores different film assembly conditions (pH and ionic strength of the polymeric solutions, chitosan degree of deacetylation, and number of deposited bilayers) of the polyelectrolyte solutions, as well as both substrate and cell surface modifications, to investigate PC3 cells adhesion properties. In summary, it is suggested that smoother surfaces with lower charge mobility, and containing low to medium concentrations of HA induce the tumor cell adhesion. The conjugation of wheat germ agglutinin (WGA) and sulfated chitosan (ChiS) on the film surface was also investigated, which proved to be a suitable strategy to boost the PC3 cell adhesion and confer anti-thrombogenic properties, respectively. In addition, interdigitated electrodes functionalized with HA/CHI presented a significant analytical performance for cell detection via impedance spectroscopy measurements, validated by visualization maps. This study highlights HA/CHI films as promising platforms able to pave the road for the development of surfaces suitable for rapid diagnostic, cell signaling and biosensing mechanisms Doutorado Engenharia Química Doutor em Engenharia Química FAPESP 2016/19976-6 CNPQ 147536/2016-2

Semiconductors thin films are the foundation of modern technology. While the nonlinear optical (NLO) properties of bulk semiconductors have been systematically studied in the last three decades, it is still a great challenge to obtain them for semiconductors thin films, as the high laser irradiance in NLO experiments tends to irreversibly damage the thin films. In addition, tuning the NLO response of semiconductor thin films by alloying and doping has not been explored yet. Here, we study the influence of the Aluminum content in AlxGa1-xN thin films and the n-type doping concentration in GaN thin films on their two-photon absorption (2PA) coefficients. For this, we investigate five different GaN-based thin films: an unintentionally doped one with no Al as a reference, two n-type doped GaN films with distinct concentrations of silicon impurities, and two AlxGa1-xN alloys with an aluminum content of 5.5% and 9.0%, respectively. The femtosecond 2PA spectra reveal that doping impurities reduce the non-linear coefficients (∼10%), while alloying with Al enhances the 2PA coefficient up to 30%. We use the model of Brandi and Araujo to determine Kane’s energy parameter related to the transition matrix element for each sample and compare them with recent theoretical studies based on the k·p theory where an excellent agreement is found.

Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2023-01-19T23:07:01Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) cassio_murilo_rodrigues_moreira.pdf: 2853689 bytes, checksum: e74967bea5acf82de277f8d79fa8c756 (MD5) Approved for entry into archive by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2023-01-20T18:37:29Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) cassio_murilo_rodrigues_moreira.pdf: 2853689 bytes, checksum: e74967bea5acf82de277f8d79fa8c756 (MD5) Made available in DSpace on 2023-01-20T18:37:29Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) cassio_murilo_rodrigues_moreira.pdf: 2853689 bytes, checksum: e74967bea5acf82de277f8d79fa8c756 (MD5) Previous issue date: 2020 Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM) A necessidade de avan?os tecnol?gicos em armazenamento de energia atrav?s de fen?menos eletroqu?micos, como os capacitores eletroqu?micos, fomentam os estudos dos materiais eletr?dicos que comp?em estes dispositivos. Na tentativa de caracterizar um poss?vel material eletr?dico para capacitores eletroqu?micos, ?xidos mistos tern?rios de n?quel, cobalto e ferro foram sintetizados em substrato de tit?nio pelo m?todo de decomposi??o t?rmica de nitratos em diferentes condi??es de temperatura. An?lises de voltametria c?clica, carga e descarga galvanost?tica e espectroscopia de imped?ncia eletroqu?mica corroboraram para caracterizar os eletrodos confeccionados como dispositivos do tipo capacitivo. A s?ntese do ?xido em 300 ?C proporcionou os melhores resultados eletroqu?micos. Por voltametria c?clica, o eletrodo confeccionado nesta temperatura exibiu uma capacit?ncia espec?fica de 56 F g?? e boa reten??o de capacit?ncia em altas velocidades de varredura. Atrav?s da carga e descarga galvanost?tica, obteve-se uma capacit?ncia de 87 F g?? e uma estabilidade c?clica de 66% em 10.000 ciclos. Em car?ter estacion?rio, a espectroscopia de imped?ncia eletroqu?mica permitiu avaliar a capacit?ncia espec?fica segundo o potencial aplicado, que revelou valores entre 42 e 66 F g??. Ainda foi feito um estudo sobre as caracter?sticas de difus?o no eletrodo, revelando uma condi??o difusional fickiana. O conjunto destes resultados permite caracterizar o ?xido sintetizado como um material promissor para compor os eletrodos de supercapacitores. Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2020. The evolution of technological advances in energy storage through electrochemical elements, such as electrochemical capacitors, foster the study of the electrode materials that make up these devices. In an attempt to characterize a possible electrode material for electrochemical capacitors, mixed ternary oxides of nickel, cobalt and iron were synthesized on titanium substrate by the method of thermal decomposition of nitrates under different temperature conditions. Analysis of cyclic voltammetry, galvanostatic charge and discharge and electrochemical impedance spectroscopy corroborated to characterize the electrodes made as capacitive type devices. The synthesis of the oxide at 300 ? C provided the best electrochemical results. By cyclic voltammetry, the electrode made at this temperature exhibited a specific capacitance of 56 F g -? and good capacitance retention at high UV lift rates. Through the galvanostatic loading and unloading, a capacitance of 87 F g -? and a cyclic stability of 66% were obtained in 10,000 cycles. In stationary character, an electrochemical food impedance spectroscopy evaluates a specific capacitance according to the specified potential, which revealed values between 42 and 66 F g -?. A study was also made about the diffusion characteristics in the electrode, revealing a Fickian diffusional condition. The set of these results allows to characterize the synthesized oxide as a promising material to compose the electrodes of supercapacitors.

Agradecimentos: This work was funded by the National Council of Technological and Scientific Development (CNPq) Grants 313019/2019-3, 165756/2014-4, 103203/2018-4, 407887/2013-0, and 435260/2018-9, Coordination for the Improvement of Higher Education Personnel (CAPES) Grant 88887.334098/2019-00, São Paulo Research Foundation (FAPESP) Grant 2012/10127-5 and National Institute of Surface Engineering (INES/CNPq) Grants 554336/2010-3 and 465423/2014-0. The authors declare no competing financial interest Abstract: Lead iodide (PbI2) is a precursor for the preparation of the organolead iodide perovskite (CH3NH3PbI3), which has been used in the fabrication of highly efficient solar cells. In this work, a novel route for the deposition of PbI2 thin films is performed by rf sputtering a target made from compressed PbI2 powder. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) revealed that the PbI2 films produced were uniform, pinhole-free, polycrystalline, and had low roughness. A small concentration of Pb nanocrystals observed within the films is attributed to differences in the sputtering yield of lead and iodide from the PbI2 target. A dependence of band gap on rf sputtering power was observed, which was associated with a reduction in the concentration of Pb nanocrystals. The PbI2 films were efficiently converted into CH3NH3PbI3 perovskite films through the immersion into a methylammonium iodide (MAI) solution, which also converted the remaining Pb nanocrystals into perovskite. This methodology has the potential to forge the way toward a new method for the fabrication of large-area perovskite solar cells CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP Fechado

The investigation of the physical properties of materials due to the reduction of dimensionality has become one of the most discussed subjects in nanotechnology. In this context, the present dissertation proposes to synthesize magnetic nanoparticles of ferrites MFe 2 O 4 (M=Co, Ni or Zn) by the proteic sol-gel method and to functionalize them with ethanoic acid (acetic), in order to promote steric impediment on the surface of the nanostructures for potential application in a photoactive layer of Polymeric Solar Cells (PSC). In this perspective, the powders of the unmodified ferrite nanoparticles, that is, without adsorbed ethanoic acid, were characterized by X-Ray Diffraction (XRD), presenting a single crystallographic phase referring to the cubic spinel structure, Transmission Electron Microscopy (TEM) indicating average particle diameters of 6.5, 12 and 11 nm for the samples of CoFe 2 O 4 , NiFe 2 O 4 and ZnFe 2 O 4 , respectively, Mössbauer Spectroscopy (MS) identifying the overlapping of the sextet (ferrimagnetic ordering) and doublet (superparamagnetic phase) lines for cobalt and nickel ferrites, while the sample of zinc was shown to be paramagnetic at room temperature, Vibrating Sample Magnetometry (VSM) indicating soft ferromagnetic behavior with saturation magnetization (M s ) inferior to the respective materials bulk, Ultraviolet-Visible Spectrophotometry (UV-Vis) featuring semiconductor samples, with values of optical gap obtained were 1.37, 1.75 and 2.12 eV for cobalt, nickel and zinc ferrites, respectively, and Thermal analysis (TA) demonstrating the efficiency of the proteic sol-gel method in the synthesis of nanostructures thermally stable. The functionalized nanoparticles were characterized by Fourier Transform Infrared Spectroscopy (FTIR), presenting the vibrational modes related to the modifying agent (ethanoic acid), while the colloidal dispersions of the modified and dispersed nanostructures in ortho-dichlorobenzene were evaluated by Dynamic Light Scattering (DLS), which showed a decrease in the solvodynamic diameter (D M ) and polydispersity index (PDI) of the samples CoFe 2 O 4 and NiFe 2 O 4 modified with 30, 180 and 720 μL ethanoic acid. A investigação das propriedades físicas de materiais em função da redução da dimensionalidade tornou-se um dos assuntos mais abordados em nanotecnologia. Nesse contexto, o presente trabalho de dissertação propõe-se em sintetizar nanopartículas magnéticas de ferritas MFe 2 O 4 (M=Co, Ni ou Zn) pelo método sol-gel proteico e funcionalizá-las com ácido etanoico (acético), a fim de promover impedimento estérico na superfície das nanoestruturas para potencial aplicação em camada fotoativa de Células Solares Poliméricas (CSP). Nessa perspectiva, os pós das nanopartículas de ferritas não modificadas, isto é, sem ácido etanoico adsorvido, foram caracterizados por Difração de Raios-X (DRX), apresentando uma única fase cristalográfica referente à estrutura de espinélio cúbico, Microscopia Eletrônica de Transmissão (MET) indicando diâmetros médios de partículas de 6,5, 12 e 11 nm para as amostras de CoFe 2 O 4 , NiFe 2 O 4 e ZnFe 2 O 4, respectivamente, Espectroscopia Mössbauer (MS) identificando a sobreposição das linhas sexteto (ordenamento ferrimagnético) e dubleto (fase superparamagnética) para as ferritas de cobalto e níquel, enquanto que a amostra de zinco demonstrou-se paramagnética, Magnetometria de Amostra Vibrante (VSM) indicando comportamento ferromagnético mole com magnetização de saturação (M s ) inferior aos respectivos materiais bulk, Espectrofotometria UV-Visível (UV-Vis) caracterizando amostras semicondutoras, cujos valores de gap óptico obtidos foram de 1,37, 1,75 e 2,12 eV para as ferritas cobalto, níquel e zinco, respectivamente, e Análise térmica (TA) demonstrando a eficiência do método sol-gel proteico na síntese de nanoestruturas termicamente estáveis. As nanopartículas funcionalizadas foram caracterizadas por Espectroscopia no Infraver- melho com Transformada de Fourier (FTIR), apresentando os modos vibracionais referentes ao agente modificante (ácido etanoico), enquanto que as dispersões coloidais das nanoestruturas modificadas e dispersas em orto-diclorobenzeno foram avaliadas por Espalhamento Dinâmico de Luz (DLS), ao qual constatou-se a diminuição do diâmetro solvodinâmico (D M ) e índice de polidispersão (IPD) das amostras CoFe 2 O 4 e NiFe 2 O 4 modificadas com 30, 180 e 720 μL de ácido etanoico.

Agradecimentos: The authors are grateful to the São Paulo Research Foundation (Nos. FAPESP 2014/03691-7, 2013/14262-7, and 2016/12807-4), CNPq, CAPES, and the Brazilian Science Without Borders "Special Visiting Scientist" Program (No. 88881.030488/2013-01) for financial support. Experimental support from the Microfabrication Laboratory of the Brazilian Nanotechnology National Laboratory (Nos. DB-C1-25094 and TEM-C1-25093) is acknowledged. This work was partly performed using the Lyon Cluster Research Platform PLYRA. We thank A. Piednoir, O. Boisron, C. Albin, and C. Clavier for technical support and J. Bellessa for fruitful discussions Abstract: The ability to disperse metallic nano-objects in a given matrix material is an important issue for the design and fabrication of functional materials. A means to monitor the spatial distribution of the nano-dopants is highly desirable but often possible only a posteriori and with destructive techniques. Here we present a spectroscopic characterization based on different plasmonic responses of silver nanoparticles, their agglomerates, and finally the percolated silver film. We demonstrate its usefulness for the specific case of their dispersion in layer-by-layer polymeric films but the method is extendable to any other host material transparent in the visible/near UV range. Individual silver nanoparticles display the well-known localized surface plasmon resonance around 400nm, which is red-shifted upon inter-particle coupling. The transition regime between weakly coupled particles and fully percolated metal films is, however, much harder to evidence unambiguously. We show here how to monitor this transition using the so-called Ferrell plasmon, a plasmonic mode of the thin film in the mid-UV, and excitable only under oblique irradiation but without specific coupling precautions. We can thus follow the entire transition from isolated to coupled and finally to fully agglomerated nanoparticles by optical spectroscopy FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Fechado

Agradecimentos: This work was supported partially by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Project 2012/10127-5 and the Instituto Nacional de Engenharia de Superficies (INES). LFZ, CF, and FA are CNPq fellows. During the development of this paper, MJMJ and VA were CAPES fellows. The authors are grateful to the LNNano, where the SEM measurements were performed. Special thanks go to C. Piacenti for his technical support Abstract: Nanostructured CrN thin films are obtained by combining RF physical vapor and dynamic glancing angle deposition using a computer-controlled substrate oscillatory motion. By using an appropriate frequency for substrate oscillation, it becomes feasible to tailor the physical properties of thin films deposited onto the substrate. The films are deposited by moving the substrate back and forward between specified angles with, among other parameters, a controlled time-dependent angular position phi(t) of the substrate. Thus, the direction of atoms striking the film changes in accordance to the position of the substrate. In this paper, we report the physical properties of a material for a varying frequency of substrate oscillation while maintaining the same angular phi(t) function (triangular function) in all the studied samples. By controlling the incidence angle phi(t) for precursor atoms impinging upon the substrate, one can prompt the formation of wavy-like periodic columnar nanostructures. The physical characteristics of the coating such as morphology, residual stress, nanohardness, crystallite size, composition, and texture of the columnar periodic multistructured films are all remarkably dependent on the oscillation frequency. The cited physical properties obtained by moving the substrate forward and back with an angular phi(t) triangular function and several periods of oscillation are reported and analyzed FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Fechado

Orientador: Prof. Dr. André Santarosa Ferlauto Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Nanociências e Materiais Avançados, Santo André, 2020. Os dispositivos de comutação resistiva (RS) (memristores) baseados em portadores iónicos chamaram a atenção devido à sua estrutura simples (apenas dois terminais), baixo consumo de energia, alta escalabilidade, endurance e possibilidade de novas arquiteturas de computação. Contudo, a variabilidade é ainda um fator limitante para as aplicações RS. Nos dispositivos RS à base de óxido, a mudança reversível (comutação) na resistência de uma fina camada dieléctrica resulta do movimento de vacâncias de oxigênio induzidas por campos elétricos elevados. Para reduzir a variabilidade, é primordial entender e controlar a formação e movimentação de vacâncias de oxigênio. Neste trabalho, foi investigada a dopagem intrínseca e extrínseca das camadas de óxido de tântalo em dispositivos RS. Películas finas de óxido de tântalo puro e Zr-doped foram preparadas por deposição laser pulsada (PLD) e caracterizadas por microscopia de força atômica (AFM), Espectroscopia de fotoelétrons excitados por raios X (XPS), e elipsometria espectroscópica (SE) para avaliar a morfologia da superfície, espessura dos filmes, estequiometria, estrutura eletrônica, e presença de defeitos. As películas puras e dopadas com Zr eram amorfas e tinham uma superfície lisa. A análise por elipsometria revela que a adição de Zr promove uma absorção ótica no sub-gap que pode ser associada com o aumento da concentração de vacâncias de oxigênio. Nas películas de óxido de tântalo puro, um efeito semelhante pode ser alcançado reduzindo a pressão parcial de oxigênio durante a deposição. Os dispositivos RS foram microfabricados por fotolitografia utilizando arquiteturas do tipo dog-bone e eletrodo de fundo comum. A resposta do dispositivo foi analisada utilizando um modelo hopping de transporte eletrônico que permite determinar a concentração de defeitos (armadilhas), que deve ser proporcional à concentração de vacâncias de oxigênio. Tal análise confirma os resultados do SE que a dopagem Zr promove a formação de vacâncias. A parametrização elétrica sistemática mostra que os dispositivos dopados com Zr são mais fiáveis, têm uma maior janela de resistência, maior rendimento, e menor tensão de formação, que pode ser atribuída a efeitos de dopagem no confinamento do filamento e formação de vacância de oxigênio. Este estudo sugere que a dopagem com Zr do memristor de óxido de tântalo é uma estratégia de engenharia de vacância promissora para melhorar o desempenho do memristor. Resistive switching (RS) devices (memristors) based on ionic carriers have attracted attention due to their simple structure (only two terminals), low energy consumption, high scalability, endurance, and possibility of novel computing architectures. However, variability is still a limiting factor for RS applications. In oxide-based RS devices, the reversible change (switching) in the resistance of a thin dielectric layer results from movement of oxygen vacancies induced by high electric fields. To reduce variability, better understating and control of oxygen vacancy formation and movement is paramount. In this work, the intrinsic and extrinsic doping of tantalum oxide layers in RS devices was investigated. Pure and Zr-doped tantalum oxide thin films were prepared by pulsed laser deposition (PLD) and characterized by atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE) to evaluate surface morphology, film thickness, stoichiometry, electronic structure, and presence of defects. The pure and Zr-doped films were amorphous and had smooth surface. SE reveals that Zr addition promotes a sub-gap optical absorption that can be associated with increased concentration of oxygen vacancies. In pure tantalum oxide films, a similar effect can be achieved by reducing the oxygen partial pressure during deposition. RS devices were micropatterned by photolithography using dog-bone and common bot contact architectures. The device response was analyzed using an electronic hopping transport model that enables determination of defect (trap) concentration, which should be proportional to the O vacancy concentration. Such analysis confirms the SE results that that Zr doping promotes O vacancy formation. Systematic electrical parametrization shows that Zr-doped devices are more reliable, have a higher resistance window, higher yield, and lower forming voltage, which might be ascribed to doping effects on filament confinement and oxygen vacancy formation. This study suggests that Zr doping of tantalum oxide memristor is a promising vacancy engineering strategy to tune memristor performance.

Double layer thin films, mechanically stable and adhering to glass, were produced through the sol–gel process, using tetraethyl orthosilicate and titanium butoxide as precursors. The refractive index of the titania and silica– titania composite layers were typically 2.1 and 1.7, and their physical thicknesses were approximately 65 nm and 81 nm, respectively, as determined by ellipsometry. These optical constants allowed attainment of quarterwave optical thicknesses at the center of the visible spectrum (550 nm) as designed, with an increase of 3.4% in transmittance. The nanometric surface roughness, measured by optical profilometry, was effective to decrease light scattering and water contact angles to below 10◦ . As novelty in dip-coated sol–gel films, superhydrophilicity for self-cleaning, antifogging, and antireflection in the mid-visible spectrum were simultaneously attained with durability of 9 weeks in the dark. Further application of UV light allowed regeneration of contact angles for self-cleaning.

Agradecimentos: This work was financially supported by FAPESP (2010/20094-1, 2017/06534-8), CNPq (422163/2018-0 and 304836/2018-4), CAPES, and National Institute for Science and Technology on Organic Electronics (INEO) (CNPq process number 465572/2014-6, FAPESP 2014/50869-6, and CAPES 23038.000776/201754). We thank Dr Ricardo Aroca, Professor Emeritus of the University of Windsor, Canada, for helping with the discussion Abstract: Organic thin films are an essential component of the structure of optical and electronic devices. However, the optical and electrical properties of these films depend on their supramolecular architecture, which may vary according to the techniques used to manufacture them. Here, the correlation between conductivity and supramolecular architecture was investigated. The supramolecular architecture was analyzed in terms of the molecular organization and J- or H-aggregation established during the fabrication of perylene tetracarboxylic diimide (PTCD) nanometric films. Three deposition techniques, Langmuir-Schaefer (LS), Langmuir-Blodgett (LB), and Physical Vapor Deposition (PVD), were evaluated. The UV-vis absorption spectra indicated that LS, LB, and PVD films grow homogeneously. Also, the presence of J and H aggregates was observed for all films, the H aggregates prevailing for the LB film. The FTIR measurements suggested that the molecular organization is similar for LS and LB films, with a tendency to form head-on organization onto a solid substrate. For the PVD film, the perylene macrocycles are inclined approximately 45 degrees relative to the substrate. AFM measurements indicated a homogenous surface for all films. In terms of electrical conductivity, the highest conductivity was found for LS, followed by LB and PVD. The conductivity values were interpreted in terms of molecular organization and J- or H-aggregate formation FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Fechado

RESUMO A técnica de deposição de filmes por spray destaca-se por sua versatilidade, simplicidade e eficiência. Neste trabalho, dois equipamentos de spray distintos foram empregados para produção de filmes de óxido de grafeno: o primeiro, um equipamento industrial para produção por método ultrassônico e o segundo, uma adaptação realizada com um aerógrafo, um solenoide, um circuito elétrico e um programa em linguagem C++, denominado de método convencional. Os filmes obtidos foram caracterizados com respeito à espessura, resistividade elétrica, transmitância e morfologia. As amostras produzidas pelo método convencional apresentaram menores espessuras e maiores transmitâncias, sendo, desse modo, mais adequadas para aplicações optoeletrônicas. Já as menores resistências de folha foram obtidas pelo método de spray ultrassônico. A morfologia dos filmes aponta melhor uniformidade para as amostras obtidas por meio da técnica ultrassônica. A análise comparativa dos resultados indicou que o equipamento convencional, apesar de ser muito mais simples e de baixo custo, foi capaz de alcançar resultados tão satisfatórios quanto os obtidos em um equipamento industrial de spray ultrassônico. A grande vantagem do equipamento industrial está na possibilidade de produção de várias amostras simultaneamente, enquanto o convencional adaptado tem como benefício a rapidez, possibilidade de deposição com folhas de óxido de grafeno maiores e acessibilidade da produção e operação do sistema. ABSTRACT The spray technique for thin film deposition stands out for its versatility, simplicity and efficiency. In this work, two different spray techniques, conventional and ultrasonic, were used for the production of graphene oxide films, the first one was an industrial equipment for ultrasonic spray production and the second, an adaptation performed with an airbrush, a solenoid, a circuit electric and a program in C ++ language, called conventional spray. The films obtained were characterized with respect to thickness, electrical resistivity, transmittance and morphology. The samples produced by the conventional method presented thicknesses and transmittances more suitable for electronic applications, since the smaller sheet resistances were obtained by the ultrasonic spray method. The morphology of the films shows a better uniformity for the samples obtained by means of the ultrasonic spray technique. The comparative analysis of the results indicated that the conventional spray equipment, although much simpler and low cost, was able to achieve results as satisfactory as those obtained in an industrial ultrasonic spray equipment. The great advantage of the industrial equipment is the possibility of producing several samples simultaneously, while the conventional spray adapted has the benefit of speed, deposition possibility with larger graphene oxide sheets and accessibility of the production and operation of the system.

The use of photovoltaic devices as converters of solar energy into electricity is a relevant technology to the global energy needs and, at the same time, it mitigates the negative impact on the environment caused by conventional sources. Although polymer solar cells are properly considered as clean and renewable source of electricity production, the processing involved in the manufacture of such devices still contains toxic elements. The formation of thin films of active layer in bulk-heterojunction organic solar cells, as example, usually uses halogenated solvents as chlorobenzene (CB), dichlorobenzene (DCB), or chloroform (CF), which represent certain risks of toxicity to the human body and to the environment. This work aims to show that it is possible to manufacture organic solar cells using less-toxic solvents, in special to the environment, whose final efficiency results are similar to those that have been processed by conventional halogenated solvents. With the aid of the Hansen solubility parameters (HSP), we identified non-halogenated and non-aromatic solvent that showed chemical compatibility with donor polymers and acceptor molecules used in the device's active layer. The fabricated devices were then characterized and their photovoltaic responses compared to the conventional equivalents.

A disposable electrochemical immunosensors is presented suitable to detect cancer biomarker p53 using screen-printed carbon electrodes modified with a layer-by-layer (LbL) matrix of carboxylated NiFe2O4 nanoparticles and polyethyleneimine, onto which anti-p53 antibodies were adsorbed. Under optimized conditions, the immunosensors exhibited high surface coverage and high concentration of immobilized antibodies, which allowed for detection of p53 in a wide dynamic range from 1.0 to 10 × 103 pg mL−1, with a limit of detection of 5.0 fg mL−1 at a working potential of 100 mV vs. Ag/AgCl. The immunosensors also exhibited good selectivity with negligible interference upon incubation in complex matrices containing high concentrations of proteins (i.e., fetal bovine serum and cell lysate). The immunosensor performance is among the best reported in the literature for determination of p53, with the additional advantage of being disposable and operating with low-volume solutions. Graphical abstract

Orientador: Prof. Dr. Marcio Vidotti Coorientador: Prof. Dr. Herbert Winnischofer Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Química. Defesa : Curitiba, 19/02/2020 Inclui referências: p. 76-93 Resumo: Este trabalho tem como objetivo estudar a influência de diferentes rotas de síntese eletroquímica de filmes finos de análogos do Azul da Prússia (AP) nas respostas espectroscópicas, morfológicas, eletroquímicas e eletrocatalíticas. Filmes de hexacianoferrato de cobalto (CoHCF) e níquel (NiHCF) foram preparados por (i) voltametria cíclica (CV), com ambos os reagentes na célula eletroquímica; e (ii) deposição potenciostática do metal (Co0 ou Ni0) seguida de voltametria cíclica (M0) em meio contendo o ânion hexacianoferrato. Com finalidade comparativa, filmes de Azul da Prússia (FeHCF) também foram preparados por CV. Os materiais de estudo foram caracterizados por espectroscopia de reflexão-absorção na região do infravermelho por transformada de Fourier (FT-IRRAS), microscopia eletrônica de varredura (SEM), espectroscopia de raios-X por energia dispersiva (EDS), microscopia de força atômica (AFM), voltametria cíclica (CV) e espectroscopia de impedância eletroquímica (EIS). Espectros de FT-IRRAS com luz polarizada e os resultados de SEM e AFM evidenciaram uma maior espessura para os filmes preparados por M0. Imagens de SEM e AFM mostraram que as rotas geram filmes com morfologias e topografias distintas. Os filmes de hexacianoferratos metálicos (MHCF) sintetizados por CV possuem estruturas mais homogêneas, enquanto os formados por M0 contêm aglomerados. As amostras também exibiram respostas voltamétricas distintas, sendo que os filmes preparados por M0 apresentaram um perfil inédito, com mais picos redox e em diferentes potenciais do que aqueles registrados para as amostras preparadas por CV, que apresentaram perfil semelhante ao já reportado na literatura. Os espectros de EDS confirmaram a presença dos elementos esperados. Os dados de EIS dos filmes foram ajustados por circuitos equivalentes distintos, indicando que diferentes elementos limitam o fluxo de corrente. As propriedades eletrocatalíticas dos filmes foram avaliadas empregando o ânion tiossulfato (S2O3 2-) como sonda eletroquímica, sendo que o hexacianoferrato(III) metálico é a espécie eletrocatalítica. os análogos apresentam início da oxidação do S2O3 2- em potencial menos positivo do que o FeHCF. Os filmes preparados por M0 exibiram sensibilidade significativamente maior do que os preparados por CV. O valor das constantes cinéticas da reação entre S2O3 2- e MHCF foram determinados por cronoamperometria e medidas de EIS. Ambos os métodos indicaram a tendência: k(CoHCF-M0) > k(FeHCF-CV) > k(NiHCF-M0) > k(CoHCF-CV) > k(NiHCF-CV). O filme de CoHCF-M0 foi o eletrocatalisador mais eficiente, pois foi o mais estável durante os experimentos, o mais reprodutível e aquele que possui a cinética de reação mais rápida com o analito, sendo superior até mesmo ao filme Azul da Prússia sintetizado para comparação. A amostra de destaque deste trabalho (CoHCF-M0) apresentou valor de sensibilidade de 1,95x10-2 A L mol-1, limite de detecção (LOD) de 1,37x10-4 mol L-1 e limite de quantificação (LOQ) de 4,58x10-4 mol L-1 na faixa linear de trabalho de 0,623 a 4,300 mmol L-1, com potencial de início de oxidação do analito em 0,60 V e constante cinética determinada por cronoamperometria e por EIS com valores de 1,08x104 L mol-1 s-1 e 5,38x10- 5 cm s-1, respectivamente. Palavras-chave: Hexacianoferratos. Filmes finos. Análogos de Azul da Prússia. Síntese eletroquímica. Eletrocatálise. Abstract: This work aims to study the influence of different routes of electrochemical synthesis of Prussian Blue (PB) analogues thin films on the spectroscopic, morphological, electrochemical and electrocatalytic responses. Cobalt (CoHCF) and nickel (NiHCF) hexacyanoferrate films were prepared by (i) cyclic voltammetry (CV), with both reagents in the electrochemical cell; and (ii) potentiostatic deposition of the metal (Co0 or Ni0) followed by cyclic voltammetry (M0) in a medium containing hexacyanoferrate anion. Prussian Blue (FeHCF) films were also prepared by CV for comparison. The materials were characterized by Fourier transform infrared reflection-absorption spectroscopy (FT-IRRAS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Polarization modulated FT-IRRAS spectra, AFM and SEM results evidenced a higher thickness for the films prepared by M0. SEM and AFM images showed that the routes generate films with distinct morphologies and topographies. CV-synthesized metallic hexacyanoferrates (MHCF) films exhibit more homogeneous structures, while those formed by M0 contain aggregates. The samples also exhibited distinct voltammetric responses, M0 route films presented an unprecedent profile, with more redox peaks and at different potentials than those recorded for the samples prepared by CV, while CV-prepared films had a profile similar to that already reported in the literature. EDS spectra confirmed the presence of the expected elements. EIS data of the films were fitted by distinct equivalent circuits, indicating that different elements limit the current flow. Thiosulfate anion (S2O3 2-) was used as probe for electrocatalysis, where metallic hexacyanoferrate(III) is the electrocatalytic species. The analogues show the onset oxidation of S2O3 2- at less positive potentials than FeHCF. Films prepared by M0 route exhibited significantly higher sensitivity than those prepared by CV. The reaction rate constants for S2O3 2- electrocatalysis were determined by chronoamperometry and EIS measurements. Both methods indicated the following tendency: k(CoHCF-M0) > k(FeHCF-CV) > k(NiHCF-M0) > k(CoHCFCV) > k(NiHCF-CV). CoHCF-M0 film was the most efficient electrocatalyst because it was the most stable during the experiments, the most reproducible and the one with the highest reaction rate with the analyte, being superior even to the Prussian Blue film synthesized for comparison. The highlighted sample of this work (CoHCF-M0) presented a sensitivity value of 1.95x10-2 A L mol-1, detection limit (LOD) of 1.37x10-4 mol L-1 and quantification limit (LOQ) of 4.58x10- 4 mol L-1 in the linear working range from 0.623 to 4.300 mmol L-1, with analyte oxidation onset potential at 0.60 V and kinetic constant determined by chronoamperometry and by EIS with values of 1.08x104 L mol-1 s-1 and 5.38x10-5 cm s-1, respectively. Keywords: Hexacyanoferrate. Thin film. Prussian Blue analogues. Electrochemical synthesis. Electrocatalysis.

Orientadores: Márcio Medeiros Soares, Marcos César de Oliveira Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin Resumo: A spintrônica é uma área de pesquisa na qual o spin eletrônico é utilizado como o grau de liberdade para o transporte, processamento e armazenamento de informações. Recentemente, muitos estudos focados na utilização de filmes finos antiferromagnéticos (AFM) como camadas ativas em dispositivos spintrônicos vêm sendo desenvolvidos. Embora os materiais AFM apresentem várias propriedades interessantes, tais como robustez contra perturbações por campos magnéticos e dinâmica de spins ultrarrápida, a manipulação dos momentos magnéticos nesses materiais é desafiadora. Uma abordagem que busca superar isso é a aplicação de deformações estruturais controladas na estrutura cristalina desses filmes finos. Essas deformações promovem alterações na anisotropia magnetocristalina desses materiais, que levam à mudança da orientação do eixo dos spins. Portanto, o objetivo desse trabalho de mestrado é a possibilidade de manipular a orientação de spins em filmes finos antiferromagnéticos de Óxido de Cobalto (CoO) a partir da aplicação de deformações macroscópicas. Com esse propósito, filmes finos policristalinos de CoO foram depositados sobre substratos cruciformes flexíveis de Kapton utilizando a técnica de Magnetron Sputtering. Para realizar deformações extensivas e compressivas nesses filmes, nós desenvolvemos um instrumento de aplicação de tensão biaxial: o 2D-MASI (Bi-axial Multi Analysis Strain Instrument). Esse dispositivo é compatível com diversas técnicas de luz síncrotron (e.g. Difração de raios-X e Espectroscopia de Absorção de raios-X) e ambientes de amostra (e.g. baixas temperaturas e alto vácuo). A deformação da estrutura cristalina da amostra foi caracterizada através de medidas in-situ de Análise de Tensão por Raios-X (do inglês XSA). Utilizando essa técnica, nós observamos que, ao aplicar uma deformação biaxial extensiva no plano da amostra, houve um aumento nas distâncias interplanares (dhkl) ao longo do plano, simultaneamente a uma contração fora do plano. Além disso, durante experimentos de contração do filme ao longo de uma direção, nós observamos o comportamento contrário: contração no plano e extensão fora do plano. Finalmente, com o objetivo de conectar os resultados obtidos através de XSA com o comportamento magnético da amostra, nós realizamos experimentos de dicroísmo linear magnético de raios-X (XMLD). Durante esses experimentos, nós adquirimos diversos espectros de absorção para os diferentes estados de deformação da amostra. Analisando as variações de intensidade dos picos desses espectros com a deformação mecânica, pudemos concluir que as alterações estruturais de fato promoveram mudanças de orientação no eixo magnético da amostra. Mais especificamente, a análise das medidas de XMLD a baixa temperatura sugere uma tendência de orientação dos spins do CoO paralela à direção em que o filme se encontra mais contraído Abstract: Spintronics is the research branch that uses the electron spin as the degree of freedom for transporting, processing, and storing information. In recent years, many studies have been focusing on applying antiferromagnetic (AFM) thin films as active layers for spintronic devices. Although AFM materials present many interesting properties, such as robustness against magnetic fields perturbations and ultrafast spin dynamics, the magnetic moment manipulation in such materials is very challenging. One approach to overcome that is through the application of controlled structural deformations to the film crystalline structure, which promote alterations to its magnetocrystalline anisotropy energy. Therefore, the goal of this Master's work is to study the possibility of manipulating the spin orientation in AFM Cobalt Oxide (CoO) thin films through the application of a controlled macroscopic strain. For this purpose, polycrystalline CoO thin films were deposited onto flexible cruciform Kapton substrates using reactive Magnetron Sputtering. To controllably perform in-plane extensive and compressive bi-axial deformations to such films, we developed a Bi-axial Multi Analysis Strain Instrument (2D-MASI). A device compatible with multiple synchrotron radiation techniques (e.g. X-ray Diffraction and X-ray Absorption Spectroscopy) and sample environments (e.g. low temperatures and high vacuum). The sample crystalline structure deformation was characterized by in-situ X-ray Stress Analysis (XSA) measurements. As a result, while performing an in-plane bi-axial extension, we observed an increase of the in-plane Bragg distances (dhkl) along with a decrease of the out-of-plane dhkl values. Moreover, by performing in-plane contraction experiments along a single direction, we observed an opposite behavior than the described above (interplanar distances' in-plane contraction and out-of-plane extension). Finally, to connect the results obtained by XSA with the sample magnetic behavior, we performed X-ray Magnetic Linear Dichroism (XMLD) experiments. During these measurements, we acquired multiple absorption spectra for different strain states. By analyzing the intensity changes within the spectrum peaks, we deduced that the sample mechanical deformation was indeed causing the film's spin axis to tilt. More specifically, the analysis of the XMLD data acquired at low temperatures suggests a tendency of spin axis orientation parallel to the film direction which is contracted the most Mestrado Física Aplicada Mestra em Física CAPES 1765877/2018 FAPESP 2018/12926-9

Orientador: Prof. Dr. Herbert Winnischofer Coorientador: Prof. Dr. Eduard Westphal Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Química. Defesa : Curitiba, 28/09/2020 Inclui referências: p. 188-202 Resumo: Ligantes anfifílicos do tipo 1,3,4- naftooxadiazol e do tipo acilhidrazona e seus respectivos complexos de rutênio bisbipiridina foram sintetizados e caracterizados por CHN, ESI-MS, RMN de 1H, FTIR, Raman, UV-Vis, voltametria cíclica e fluorescência. Também foram sintetizados e caracterizados por essas técnicas complexos com ligantes derivados de 1,3,4-oxadiazol, um cluster trinuclear de rutênio (Ru3Oiso1) e um bisbipiridina rutênio RuDiso1. Os resultados demonstram sucesso nas sínteses dos compostos. Posteriormente desenvolvemos um estudo dos compostos na cuba de Langmuir-Blodgett, identificando a isoterma e área por molécula típica de cada composto, testes de estabilidade e ciclos de compressão e descompressão dos filmes, além de caracterizar os filmes de Langmuir por BAM e PM-IRRAS. A partir da identificação da melhor condição, depositamos os compostos em diferentes substratos e caracterizamos os filmes de Langmuir-Blodgett por UV-Vis, IRRAS, Raman, voltametria cíclica e fluorescência. Identificamos que um dos ligantes derivados de 1,3,4-naftooxadiazol apresenta comportamento de cristal líquido. O cluster de rutênio apresentou fluorescência em solução e em filme LB, atribuído a um cruzamento entre sistemas do estado tripleto do ligante iso1 coordenado ao rutênio. Estudamos derivados de azopiridina anfifílicos frente a isomerização pela ação de uma lâmpada UV, por RMN de 1H e infravermelho em solução. Caracterizamos os azo-compostos na forma de filmes de Langmuir e Langmuir- Blodgett pelas mesmas técnicas mencionadas acima. Desenvolvemos um estudo de comutação por fotoisomerização trans/cis e tratamento térmico dos compostos azopiridínicos em filmes LB. Os resultados obtidos por UV-Vis e IRRAS demonstram a possibilidade de aplicar esses filmes como dispositivos de memória para armazenamento de dados. Palavras-chave: 1,3,4-oxadiazol. Acilhidrazonas. Azo-compostos. Rutênio. Filmes Langmuir-Blodgett. Abstract: Amphiphiles of 1,3,4- naphthooxadiazole and acylhydrazone and their respective ruthenium bispyridine complexes were synthesized and characterized by CHN, ESI-MS, 1H NMR, FTIR, Raman, UV-Vis, cyclic voltammetry and fluorescence. A trinuclear ruthenium cluster (Ru3Oiso1) and ruthenium bisbipyridine RuDiso1 with 1,3,4-oxadiazole were also synthesized and characterized by these techniques. The results demonstrate success in the synthesis of the compounds. Subsequently, we developed studies with Langmuir trough, identifying the isotherms and area per molecule for each compound, in addition to stability tests, compression and decompression cycles and characterizing the Langmuir films by BAM and PM-IRRAS. We deposit the compounds on different substrates and characterize the Langmuir-Blodgett films by UV-Vis, IRRAS, Raman, cyclic voltammetry and fluorescence. The 1,3,4- naphthooxadiazole derivatives exhibit a liquid crystal behavior. The ruthenium cluster showed fluorescence in solution and in LB film, attributed to a crossing between systems of the triplet state of the iso1 ligand coordinated with ruthenium. We studied amphiphilic azopyridine derivatives against isomerization by the action of a UV lamp, by 1H NMR and infrared in solution. We characterize the azocompounds as Langmuir and Langmuir-Blodgett films using the same techniques mentioned above. We developed a study of switching by trans/cis photoisomerization and heat treatment of azopyridine compounds in LB films. The results obtained by UV-Vis and IRRAS demonstrate the possibility of applying these films as memory devices for data storage. Key-words: 1,3,4-oxadiazole. Acylhydrazones. Azo compounds. Ruthenium. Langmuir-Blodgett films.

Orientador: Prof. Dr. Aldo José Gorgatti Zarbin Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Química. Defesa : Curitiba, 18/02/2020 Inclui referências: p. 149-163 Resumo: Dentre as inovações das últimas décadas que viabilizam a crescente demanda por novos materiais e dispositivos mais eficientes, destacam-se as tecnologias à base de nanomateriais de carbono, utilizados em aplicações que necessitam de condutividade elétrica, resistência mecânica e química, materiais leves, flexíveis e renováveis. A utilização desses nanomateriais geralmente é pautada no emprego de estruturas individualizadas e dispersas em meios líquidos, principalmente aplicações que demandam alta performance ou transparência, como filmes finos condutores e transparentes. Para qualquer aplicação é necessário conhecimento profundo acerca das propriedades dessas dispersões e das relações entre tais propriedades e as características dos dispositivos finais. O presente trabalho visa ampliar alguns conceitos de preparação e estabilização de dispersões de nanomateriais de carbono, e ampliar alguns conceitos de preparação de filmes finos em interfaces líquido-líquido, através da relação entre dispersante e/ou cargas elétricas nos materiais com estabilidade coloidal e através das relações entre as propriedades dessas dispersões e dos filmes finos formados em diferentes interface líquido-líquido, respectivamente. Foi demonstrado que alguns solventes puros, como clorofórmio, ou contendo impurezas, como tetraidrofurano (THF) com 2,6-di-terc-butil-4-metilfenol (BHT), são capazes de dispersar nanotubos de carbono, formando dispersões liofóbicas que permanecem metaestáveis por estabilização eletrostática, decorrente da formação de cargas elétricas nos materiais durante a sonicação. Dispersões de nanotubos de carbono em THF contendo BHT podem ser utilizadas como precursoras de dispersões aquosas metaestáveis não passivadas e não funcionalizadas, formadas por nanotubos individualizados e estabilizados também por repulsão eletrostáticas. Cargas elétricas são geradas pela oxidação do BHT, que doa elétrons para os nanotubos durante a sonicação em THF, e esses elétrons são mantidos após a transferência para água. Dispersões orgânicas e a dispersão aquosa de nanotubos de carbono foram utilizadas na preparação de filmes finos em interfaces líquido-líquido utilizando-se o método interfacial. A dispersão aquosa metaestável de nanotubos sempre forma filmes finos com misturas líquidas de tensão interfacial maior que 20 mJ m-2. Contudo, as dispersões orgânicas formam filmes apenas se o dispersante dos nanotubos for um líquido aromático e se a interface for aquosa. Foram preparadas dispersões aquosas de fulereno C60 e de grafeno, a partir dos respectivos compostos de intercalação com potássio metálico e das soluções desses compostos em THF. Tais dispersões aquosas também apresentam natureza liofóbica e são metaestáveis devido à repulsão eletrostática. Dois conceitos demonstrados anteriormente foram generalizados a partir dos experimentos com as dispersões de C60 e grafeno, (i) a natureza eletrônica das cargas elétricas que mantêm as dispersões estáveis, e (ii) a formação de filmes finos em interfaces líquido-líquido a partir de dispersões metaestáveis e com misturas de solventes de tensão interfacial maior que 20 mJ m-2, independentemente da morfologia ou dimensionalidade do nanomaterial de carbono. Palavras-chave: Nanomateriais de carbono. Dispersões aquosas. Espectroscopia Raman. Filmes finos. Interfaces líquido-líquido. Abstract: Among the innovations from last decades that enable the crescent demand for new materials and more efficient devices, carbon nanomaterials-based technologies stand out, and they have been used in application that demand electrical conductivity, mechanical and chemical resistance, and lightweight, flexible and renewable materials. Applications for these nanomateriais are based on individualized structures dispersed in liquid media, especially for transparent devices or high-performance ones, like conductive and transparent thin films. For any application is necessary deep knowledge about dispersions properties and the relations between such properties and the characteristics of the final devices. This work aims the establishment of new concepts concerning the preparation and stabilization of carbon nanomaterials dispersions, through the correlation between dispersants or electrical charges and colloidal stability, as well as the enlargement of concepts about the preparation of thin films in liquid-liquid interfaces, through the relations between dispersions properties and some characteristics of thin films prepared in different liquid-liquid interfaces. It was demonstrated that some pure solvents, as chloroform, or impure ones, like tetrahydrofuran (THF) containing 2,6- di-terc-butyl-4-methylphenol (BHT), are able to disperse carbon nanotubes, forming lyophobic dispersions that are metastable due to electrostatic stability, as a consequence of electrical charges formation on those materials during sonication. Carbon nanotubes dispersed in THF containing BHT can be used as precursors for aqueous and metastable dispersions without passivant agents or functionalization, that are formed by individualized nanotubes also stabilized by electrostatic repulsion. Electrical charges are produced by BHT oxidation, which donates electrons to nanotubes during sonication in THF, and those electrons are kept after water transfer. Organic and aqueous dispersions of carbon nanotubes were used to prepare thin films in liquid-liquid interfaces, using the interfacial method. Metastable aqueous dispersion always produces a thin film if the liquid mixtures have interfacial tension higher than 20 mJ m-2. However, organic dispersions produce thin films only if the dispersant for nanotubes is an aromatic liquid and using aqueous interfaces. It was prepared aqueous dispersions of fullerene C60 and graphene, starting from the respective salts with metallic potassium e from them solutions in THF. Such aqueous dispersions have also lyophobic nature and are metastable due to electrostatic repulsion. Two concepts explored before were generalized from the experiments with the C60 and graphene dispersions, (i) the electronic nature of electrical charges the maintain these dispersions stable, and (ii) the formation of thin films in liquid-liquid interfaces from metastable dispersions mixed with solvents that produce liquid mixtures with interfacial tensions higher than 20 mJ m-2, regardless the morphology or dimensionality of the carbon nanomaterial. Keywords: Carbon nanomaterials. Aqueous dispersions. Raman spectroscopy. Thin films. Liquid-liquid interfaces.

Fluorescent organic molecules have received great attention due to their largest applications, for example, in DNA and RNA spectroscopies studies, development of new photoluminescence bioprobes, an...

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Campus Joinville, Programa de Pós-Graduação em Engenharia e Ciências Mecânicas, Joinville, 2020. Um dos grandes desafios da indústria marítima relaciona-se ao controle dos processos de bioincrustação em superfícies submersas em ambiente aquático por longos períodos. Neste sentido, verifica-se um grande esforço para o desenvolvimento de agentes antincrustantes com impactos ambientais aceitáveis a fim de substituir o biocida tributilestanho, amplamente utilizado até 2008 para grandes embarcações. Neste sentido, no presente trabalho verificou-se o potencial de aplicação de filmes finos de TiO2 em diferentes espessuras como agente antincrustante. Desta forma, filmes com diferentes espessuras de TiO2 foram depositados sobre aço inoxidável AISI 316L pela técnica de magnetron sputtering e, então, caracterizados pelas técnicas de perfilometria, espectroscopia Raman, difração de raios-X e avaliação do ângulos de contato antes e depois da irradiação por UV-A e UV-C. A caracterização da propriedade antincrustantes dos filmes foi realizada por meio de experimento de campo, onde superfícies com e sem revestimento foram submersas por 110 dias com acompanhamento fotográfico e quantitativo do desenvolvimento da bioincrustação marinha no Rio Cubatão com auxílio do software PhotoQuad. Os filmes avaliados consistiam em revestimentos de espessuras de 3,5 nm até 172,5 nm de TiO2, sendo que o filme mais fino apresentou característica amorfa e os mais espessos apresentaram estrutura cristalina composta por rutile e anatase. No que diz respeito à molhabilidade, todas as espessuras apresentaram hidrofilicidade fotoinduzida para ambos os comprimentos de onda. Por outro lado, o revestimento com espessura de 172,5 nm se destacou por apresentar transição mais rápida para hidrofilicidade e ângulo de contato de até 16 graus para UV-A. Acerca da bioincrustação, foi possível verificar um atraso no início do processo de incrustação da superfície, independentemente da espessura do filme. Também se verificou a redução da área total média incrustada por Balanus Amphitrite em superfícies com revestimento de TiO2 em relação às amostras sem revestimento de até 36%. No estudo identificou-se as diatomáceas Amphora coffeaeformis, Terpsinoë musica e Cocconeis fluviatilis como espécies microincrustantes das superfícies submersas com auxílio da técnica de MEV. No presente estudo verificou-se que filmes com espessuras muito finas, da ordem de 3,5nm até os mais espessos apresentaram ação antincrustante e retardamento do início do processo de bioincrustação. Abstract: One of the great challenges of the maritime industry is related to the control of biofouling processes on surfaces submerged in the aquatic environment for long periods of time. In this sense, there is a great effort to develop antifouling agents with acceptable environmental impacts in order to replace the tributyltin biocide, widely used until 2008 for large vessels. Thus, in the present work it was verified the potential of applying thin films of TiO2 in different thicknesses as an antifouling agent. Therefore, films with different thicknesses of TiO2 were deposited on AISI 316L stainless steel by the technique of magnetron sputtering and, then, characterized by the techniques of profilometry, Raman spectroscopy, X-ray diffraction and evaluation of the contact angles before and after irradiation by UV-A and UV-C. The characterization of the antifouling properties of the films was carried out through a field experiment, where surfaces with and without coating were submerged for 110 days with photographic and quantitative monitoring of the development of marine biofouling in the Cubatão River with the aid of the PhotoQuad software. The evaluated films consisted of coatings of thickness from 3.5 nm to 172.5 nm of TiO2, with the thinnest film presenting an amorphous characteristic and the thickest films presenting a crystalline structure composed of rutile and anatase. Regarding the wettability, all thicknesses showed photoinduced hydrophilicity for both wavelengths. On the other hand, the 172.5 nm thick coating stood out for presenting a faster transition to hydrophilicity and a contact angle of up to 16 degrees for UV-A. Regarding biofouling, it was possible to verify a delay in the beginning of the fouling process of the surface, regardless of the thickness of the film. There was also a reduction in the mean total area fouled by Balanus Amphitrite on surfaces with TiO2 coating compared to samples without coating by up to 36%. In the study, the diatoms Amphora coffeaeformis, Terpsinoë musica and Cocconeis fluviatilis were identified as microfoulers species of the submerged surfaces with the aid of the SEM technique. In the present study it was found that films with very thin thicknesses, in the order of 3.5nm to the thickest ones, presented anti-fouling and delayed action in the beginning of the biofouling process.

Agradecimentos: The authors are grateful to FAPESP (Grant 2014/03691-7), CNPq (Grant 147530/2014), and CAPES for financial support and the Microfabrication Laboratory in the Brazilian Nanotechnology National Laboratory for the experimental support Abstract: The development of sensors based on nanostructures is an important task in fundamental and applied sciences to increase their sensitivity and selectivity. A better comprehension of materials aggregation at the nanoscale can provide insights and innovations for sensing and electronic appliances. We analyzed the electrical properties of polyelectrolytes assembled in a multilayered architecture with nanometric thickness control. We have fabricated layer-by-layer (LbL) thin films alternating positively charged poly(diallyldimethylammonium chloride) (PDDA) and negatively charged poly-(styrenesulfonate) (PSS) in a PDDA/PSS architecture. A homemade setup tracked the nanostructure growth by measuring the capacitance after each deposited layer onto gold interdigitated electrodes (IDEs). The capacitance increase linearly after each adsorbed bilayer, which is associated with the dielectric layer accumulated onto the IDEs. We interpreted such behavior in terms of the electrostatic potential on the IDEs, resulting in a dielectric constant of 21 +/- 3 for the PDDA/PSS film. Furthermore, we observed the capacitance changing in a zigzag-like behavior according to the outermost deposited layer due to the charge reversal process. Polycation surface charge density was estimated as (5.8 +/- 0.2) x 10(-20) c/mu m(2). We also analyzed the strong and weak character of PDDA and poly(allylamine hydrochloride) (PAH). The methodology proposed here allows for a better material choice that best suits a particular LbL application. Besides, the quantitative evaluation of the outermost layer charge density should enhance the adsorption of molecules that are routinely employed as active layers in (bio)sensing applications, contributing to improvements in (bio)sensor engineering FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Fechado

The stopping power and straggling of backscattered protons on nanometric Pt films were measured at low to medium energies (60–250 keV) by using the medium-energy ion scattering technique. The stopping power results are in good agreement with the most recent measurements by Primetzhofer Phys. Rev. B 86, 094102 (2012) and are well described by the free electron gas model at low projectile energies. Nevertheless, the straggling results are strongly underestimated by well-established formulas up to a factor of two. Alternatively, we propose a model for the energy-loss straggling that takes into account the inhomogeneous electron-gas response, based on the electron-loss function of the material, along with bunching effects. This approach yields remarkable agreement with the experimental data, indicating that the observed enhancement in energy-loss straggling is due to bunching effects in an inhomogeneous electron system. Nonlinear effects are of minor importance for the energy-loss straggling.