Search

Whereas lanthanide-based upconverting particles are promising candidates for several micro- and nanothermometry applications, understanding spatially varying effects related to their internal dynamics and interactions with the environment near the surface remains challenging. To separate the bulk from the surface response, this work proposes and performs hyperspectral sample-scanning experiments to obtain spatially resolved thermometric measurements on single microparticles of NaYF

In recent years, nanoparticulate materials have aroused interest in the field of organic electronics due to their high versatility which increases the efficiency of devices. In this work, four different stable conformations based on the organic semiconductors P3HT and PC71BM were synthesized using the nanoprecipitation method, including blend and core-shell nanoparticles. All nanoparticles were obtained free of surfactants and in aqueous suspensions following the line of ecologically correct routes. The structural and optoelectronic properties of the nanoparticles were investigated by dynamic light scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV-visible absorption spectroscopy and UV-visible photoluminescence (PL). Even in aqueous media, the blend and core-shell nanoparticles exhibited a greater light absorption capacity, and these conformations proved to be effective in the process of dissociation of excitons that occurs at the P3HT donor/PC71BM acceptor interface. With all these characteristics and allied to the fact that the nanoparticles are surfactant-free aqueous suspensions, this work paves the way for the use of these colloids as a photoactive layer of organic photovoltaic devices that interface with biological systems.

Carotenoids over-producing yeast has become a focus of interest of the biorefineries, in which the integration of the bioproduction with the following downstream processing units for the recovery and purification of carotenoids and other value-added byproducts is crucial to improve the sustainability and profitability of the overall bioprocess. Aiming the future implementation of Phaffia rhodozyma-based biorefineries, in this work, an integrative process for fractionation of intracellular compounds from P. rhodozyma biomass using non-hazardous bio-based solvents was developed. After one-extraction step, the total amount of astaxanthin, β-carotene, lipids and proteins recovered was 63.11 µg/g

We employed hyperspectral imaging with nanometric spatial resolution in single NaYF4: Yb3+/Er3+ microcrystals to resolve spatially the luminescence spectrum and to study the temperature distribution at the diffraction limit.

Made available in DSpace on 2022-04-28T17:30:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-12-24 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) Higher Education Commission (HEC) Pakistan The development of broad-spectrum photocatalytic materials that allow the use of a larger portion (UV to NIR) of the solar spectrum for photocatalytic processes has attracted great attention. Among visible light-active photocatalysts, silver phosphate (Ag3PO4) stands out prominent for its high photocatalytic activity towards the degradation of different pollutants. However, the full potential of this photocatalyst is limited by its inherent low photostability arising from self-photoreduction and its inability to efficiently use light beyond the UV-Vis range of the solar spectrum. To address these fundamental limitations of Ag3PO4, we have developed a smart photocatalytic system by combining the interesting upconversion property of NaYbF4:Tm3+ upconverting particles (UCPs) with the exceptionally high photocatalytic activity of Ag3PO4 and the oxidizing capacity of H2O2. In this UCPs/photocatalyst/oxidant (NaYbF4:Tm3+/Ag3PO4/H2O2) system, the NIR-to-UV/visible UCPs can convert low energy NIR photons into high energy UV-visible photons that can be absorbed by Ag3PO4, thus photo-exciting (activating) it indirectly under NIR illumination. Similarly, the oxidant (H2O2) prevents self-reduction and/or assists in regeneration of Ag3PO4 through a Fenton-like process, thus ensuring the photostability and recyclability of Ag3PO4. Interestingly, the Ag3PO4/H2O2 system remains active generating reactive oxygen species even after the photoexcitation process is turned off (dark conditions). The proposed broad spectrum photocatalytic system (UCPs/Ag3PO4/H2O2) was found to exhibit a high photocatalytic response (98% degradation of crystal violet dye in 90 min) under NIR illumination from a 980 nm laser and still a higher response (100% removal in less than 8 min) under direct visible light from low-cost blue emitting LEDs. Sao Paulo State Univ UNESP, Inst Chem, BR-14800060 Araraquara, SP, Brazil Univ Peshawar, Inst Chem Sci, POB 25120, Peshawar, Pakistan Sao Paulo State Univ UNESP, Inst Chem, BR-14800060 Araraquara, SP, Brazil FAPESP: 2018/15791-7 FAPESP: 2018/01934-0 CNPq: 166682/2020-9 Higher Education Commission (HEC) Pakistan: 9286 FAPESP: 2015/22828-6

Ultrafast transient absorption spectroscopy, NOESY-NMR, and EPR spectroscopy shed light on how π-π stacking interactions combined with electrostatic interactions can be used to form stable ion-pair complexes between pyrylium and tetraarylborate ions in which the interaction of the π-delocalized clouds promotes the observation of new radiative processes and also electron transfer processes excitation using visible light. The results exhibit a striking combination of properties, chemical stability and photophysical and photochemical events, that make these ion-pair complexes as a step toward the realization of chromophore/luminescent materials and also their use as a new monophotoinitiator system in radical polymerization reactions.

To address the problems associated with the use of unsupported nanomaterials, in general, and molybdenum disulfide (MoS

Quick-response (QR) codes are gaining much consideration in recent years due to their simple and fast readability compared with conventional barcodes. QR codes provide increased storage capacity and safer access to information, fostering the development of optical or printed smart tags as preferred tools for the Internet of Things (IoT). Herein, the combination of Yb3+/Er3+-doped NaGdF4 upconverting nanoparticles (UCNPs) with recovered plastic for the fabrication of sustainable screen-printed QR codes is reported. Their photothermal response under distinct power densities of the 980 nm laser irradiation (15���115 W cm���2) induces color-tuning and temperature sensing. This power dependence is exploited to design a double key molecular keylock accessed by a smartphone camera through the red (R), green (G), and blue (B) (RGB) additive color model and upconversion thermometry. The latter is based on the integrated areas of the 2H11/2���4I15/2 and 4S3/2���4I15/2 Er3+ transitions using the interconnectivity and integration into the IoT network of the mobile phone to download the temperature calibration curve of the UCNPs from a remote server. These findings illustrate the potential of QR codes-bearing UCNPs toward the design of smart tags for mobile optical sensing and anticounterfeiting., This project has received funding from the European Union's Horizon 2020 FET Open programme under grant agreement No 801305 (NanoTBTech). This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No. 823941.

Phosphotellurite based glasses have interesting features such as low characteristic temperatures, high glass forming ability, high thermal stability against crystallization and a broad transparency window from ultraviolet (UV) to near-infrared (NIR), which makes them promising materials for photonic applications. In this work, phosphotellurite binary glasses, having a composition (100 - x)TeO2 - xBa(PO3)2 with x varying from 1 to 20 mol%, were synthesized by the conventional melt-quenching method in covered gold crucibles under air. Optical, physical and structural properties of the new glass samples were investigated by differential scanning calorimetry, X-ray diffraction, Raman spectroscopy, transmission electron microscopy, linear optical absorption from UV to NIR, IR transmittance, and optical limiting experiments. Transparent glass-ceramics in the visible range were obtained for phosphotellurite samples containing 2, 4 and 6 mol% of Ba(PO3)2 and the phase crystallization was investigated through Rietveld analysis and transmission electron microscopy. The incorporation of Ba(PO3)2 into the TeO2 network drastically increases the thermal stability against devitrification and helps to shift the infrared multiphonon absorption edge to longer wavelengths. Nonlinear measurements performed with a picosecond laser at 532 nm indicate large effective nonlinear absorption coefficients for all samples. In summary, the dependence of the spectroscopic properties on the compositions of the samples revealed promising transparent glass and glass-ceramics for photonic applications.

O presente trabalho discute os recentes avanços na biossíntese e na produção de celulose bacteriana (CB) pela gram-negativa, aeróbia e aceto-ácida Gluconacetobacter. xylinus. A CB se difere de seu par vegetal, principalmente devido ao seu caráter de fibras nanométricas, contra o caráter micrométrico da vegetal, são extruídas através da parede celular de G. xylinus, com isso sua estrutura macroscópica é mecanicamente e fisicamente mais resistente, abrindo grandes oportunidades de aplicações tecnológicas e biológicas, muito além das obtidas pela celulose vegetal. O desafio atual está no aumento da produção de CB, que se debruça num maior entendimento de sua biossíntese para que seja possível uma posterior manipulação genético-bioquímica oriundas do recente avanço na biologia molecular e nos bioprocessos. São relacionados trabalhos utilizando a CB como base para produção de compósitos como também o que a está sendo feito de mais atual com este material biológico.The present paper discusses the recent advances about the biosynthesis and production of bacterial cellulose (BC), from gram-negative, aerobic and acetic acid Gluconcetobacter xylinus (Gx). The BC differs from his vegetal pair, mainly due his feature of nanometric fibers, as opposed to micrometric feature of vegetal cellulose, are extruded through the cellular wall of Gx, thereby the macroscopic structure of BC is mechanically and physically more resistant, open big opportunities of biological and technological applications, apart from that obtained by vegetal cellulose. The actual challenge is in the grown of production of BC, which deals a superior understanding of his biosynthesis, to makes possible a later genetic-biochemical manipulation derived from recent advances in molecular biology. Are related works using the BC for production of composites and also what is being done of more actual with this biological material.

This study aimed to evaluate the potential of bacterial cellulose-hydroxyapatite (BC-HA) composites associated with osteogenic growth peptide (OGP) or pentapeptide OGP(10-14) in bone regeneration in critical-size calvarial defects in mice. In this study, the BC-HA, BC-HA-OGP, and BC-HA-OGP(10-14) membranes were analyzed at 3, 7, 15, 30, 60, and 90 days. In each period, the specimens were evaluated by micro-computed tomography (µCT), descriptive histology, gene expression of bone biomarkers by qPCR and VEGFR-2 (vascular endothelial growth factor) quantification by ELISA. Three days post-operative, Runx2, Tnfrsf11b and Bglap bone biomarkers were upregulated mainly by BC-HA OGP and BC-HA OGP(10-14) membranes, suggesting an acceleration of the osteoblast differentiation/activity with the use of these biomaterials. At 60 and 90 days, a high percentage of bone formation was observed by µCT for BC-HA and BC-HA OGP(10-14) membranes. High expression of some bone biomarkers, such as Alpl, Spp1, and Tnfrsf11b, was also observed for the same membranes on days 60 and 90. In conclusion, the BC-HA membrane promoted a better bone formation in critical-size mice calvarial defects. Nevertheless, incorporation of the peptides at the concentration of 10(-9) mol L(-1) did not improve bone regeneration potential in the long-term.

C18-sphingosine 1-phosphate (C18-SPP) is a sphingolipid with important functional and structural roles in cells. In this paper we report a new capillary electrophoresis technique that is coupled to a laser-induced fluorescence detection (CE-LIF) method to quantify the level of C18-SPP in biological samples. The method utilizes a commercial standard C17-sphingosine 1-phosphate (C17-SPP) derivatized with naphthalene-2,3-dicarboxaldehyde (NDA), a fluorogenic dye used to label primary amines. The detection limit for the C17-SPP NDA was 0.54 fmol. We quantified the C18-SPP in leukemic human cells before and after irradiation by gamma rays. We demonstrated that the amounts of this sphingolipid decreased after the irradiation. In a second part of this work, we used the technique to evaluate the ability of a novel transparent fused-silica capillary, which allows the use of fused-silica capillaries without burning a window. Solarization, homogeneity, and sensitivity were studied using this capillary. The results demonstrate that this new durable capillary can provide a sensitive and reproducible quantitation procedure for CE-LIF studies.

The interaction between metaphosphate chains and the metal ions Ca2+ and Eu3+ has been studied in water by Eu3+ luminescence, infrared absorption, and 31P NMR spectroscopy. Two main families of sites could be identified for the metal ions in the aqueous polyphosphate colloidal systems: (1) cagelike sites provided by the polyphosphate chain and (2) a family which arises following saturation of cagelike sites. Occupation of this second family leads to supramolecular interactions between polyphosphate chains and the consequent destabilization of the colloidal system. In the polyphosphate-Ca2+ system, this destabilization appears as a coacervation process. Equilibrium existing between colloidal species as a function of the compositions could be reasoned based on the spectroscopic measurements. The determination of coordination numbers and the correlation of the results with the observation of coacervates show that Eu3+ luminescence properties can be used to probe in a unique way the coacervation process.