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Immunoassays are important for the diagnosis of many diseases. Efficient methods for the immobilization of the biorecognition elements is a relevant subject because the antibody loading is directly related to the detection range and sensitivity. Here different self-assembled films were explored to take advantage of polar oxygenated groups from graphene oxide (GO) structure. Surface plasmon resonance (SPR) sensors were modified with different GO self-assembled films and compared to the well-established thiol-functionalization with 11-MUA (11- mercaptoundecanoic acid). Self-assembled cysteamine/GO functionalized sensor (Cys-GOSA) provided the highest protein loading (7.66 × 10−12 mol cm−2 against 1.29 × 10−11 mol cm−2 for the traditional thiol-functionalization). The Langmuir-Blodgett (LB) films of GO were composed of aggregates and empty spaces, which hindered the antibody anchoring (around 6.38 × 10−12 to 3.45 × 10−12 mol cm−2). The SPR response of the Cys-GOSA-modified sensor to the 4.0 ng mL−1 PSA was 125% higher than the thiol-functionalized sensor at the same concentration. This result indicates a simple and promising surface modification strategy for many important applications, not limited to SPR sensors, but for all immunoreaction-based assays as enzyme-linked immunosorbent assay (ELISA), electrochemical (e.g. amperometric and impedimetric) and quartz crystal microbalance (QCM) based sensors.

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.

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.

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.

In this work, small molecule-based solar cells were produced with a solution-processed diketopyrrolopyrrole-terthiophene (DPP3Th) as electron donor material and thermally evaporated fullerene (C70) film as acceptor material. The DPP3Th molecule was synthesized by the Suzuki cross-coupling reaction, resulting in energy values of the Highest Occupied Molecular Orbital (HOMO) equal to −5.30 eV, Lowest Unoccupied Molecular Orbital (LUMO) equal to −3.80 eV and optical band gap (Eg) of 1.60 eV. Theoretical simulation pointed out a limited torsional movement between the DPP and thiophene units, which contribute to shift the absorption edge of the DPP3Th to higher wavelengths and thus, resulting in extended photon collection. The DPP3Th and C70 molecules present complementary absorbance spectra (from 300 nm up to ca. 725 nm). Moreover, the DPP3Th/C70 interface provides a favorable energy barrier to electron transfer from the donor to the acceptor, resulting in open circuit voltage (Voc) of 0.72 V which is a promising step toward application in solar cells.

Peptides with an active redox molecule are incorporated into nanostructured films for electrochemical biosensors with stable and controllable physicochemical properties. In this study, we synthesized three ferrocene (Fc)-containing peptides with the sequence Fc-Glu-(Ala)n-Cys-NH2, which could form self-assembled monolayers on gold and be attached to antibodies. The peptide with two alanines (n = 2) yielded the immunosensor with the highest performance in detecting C-reactive protein (CRP), a biomarker of inflammation. Using electrochemical impedance-derived capacitive spectroscopy, the limit of detection was 240 pM with a dynamic range that included clinically relevant CRP concentrations. With a combination of electrochemical methods and polarization-modulated infrared reflection–absorption spectroscopy, we identified the chemical groups involved in the antibody-CRP interaction, and were able to relate the highest performance for the peptide with n = 2 to chain length and efficient packing in the organized films. These strategies to design peptides and methods to fabricate the immunosensors are generic, and can be applied to other types of biosensors, including in low cost platforms for point-of-care diagnostics., CNPq, CAPES and FAPESP (2018/22214-6, 2017/24839-0, 2013/07600-3, 2018/18953-8 and 2018/18231-2) supported the work. EMC is a senior researcher of the CNPq (grant 301975/2018-3).

The fight against drug resistance in chemotherapy requires a molecular-level understanding of the drug interaction with cell membranes, which today is feasible with membrane models. In this study, we report on the interaction of gemcitabine (GEM), a pyrimidine nucleoside antimetabolite used to treat pancreatic cancer, with Langmuir films that mimic healthy and cancerous cell membranes. The cell membrane models were made with eight compositions of a quaternary mixture containing 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine (DPPC), 1,2-dipalmitoyl-sn-glycero-3-phosphoserine (DPPS), sphingomyelin (SM), and cholesterol (CHOL). The relative concentration of SM was increased so that four of these compositions represented cancerous cells. GEM was found to increase the mean molecular area, also increasing their surface elasticity, with stronger interactions being observed for membranes corresponding to cancerous cells. More specifically, GEM penetrated deepest in the membrane with the highest SM concentration (40 mol%), as inferred from polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). This finding was confirmed with molecular dynamics simulations that also indicated how GEM approaches the membrane, which could be useful for guiding the design of drug delivery systems. The experimental and simulation results are consistent with the preferential attachment of GEM onto cancerous cells and highlight the role of SM on drug-cell interactions.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are promising for gas sensors owing to their large surface-to-volume ratios, but the long recovery times stemming from the slow molecular desorption have been an important limitation. In this work, we report on a sensor for nitrogen dioxide (NO2) made with a diselenide (WSe2) monolayer synthesized via chemical vapor deposition, which functions within a range of concentrations from 100 ppb to 5 ppm and at various temperatures, including room temperature. When operated at an optimized temperature of 250 °C, the WSe2 sensor exhibited the fast recovery, with the response (τres) and recovery (τrec) times of 18 s and 38 s, respectively, when exposed to 100 ppb NO2. The sensor also features high selectivity toward NO2 in the presence of other target gases, in addition to reversibility and long-term stability within 60 days. The overall characteristics of the WSe2 sensor make it suitable to monitor indoor/outdoor environments, mainly if further optimization is made with sensor design based on a model for the sensing mechanism we present in this paper.

In this work, reduced graphene oxide:3,4,9,10-perylenetetracarboxylic dianhydride nanohybrid was prepared by a modified Hummers method which resulted in effective functionalization of graphene sheets. In this procedure, the perylene molecules were included at the reaction medium of graphene oxide, where the acid promotes hydrolysis of the anhydride, forming carboxylic acids; these groups react with hydroxyl groups of graphene oxide, generating ester bonds between graphene oxide and perylene, followed by a reduction through thermal annealing in air. The resulting interfacial nanohybrid film combines optical and electrical features of both materials, being a promising functional interlayer in organic-inorganic based devices. Herein, the thin film was tested in organic solar cells; the photovoltaic response pointed out that the dipole character of the nanohybrid enhances the fill factor and open circuit voltage parameters, when compared with the solar cell without buffer layer or having a polymeric hole transporting layer. After that, the optimized solar cells displayed open circuit voltage of 0.76 V, short circuit current density of 11.61 mA/cm2, fill factor of 53 % and power conversion efficiency of 4.70 % under AM1.5 illumination, where the nanohybrid film may act as a complementary absorbing layer and as hole injection layer, pointing out the potential use of this compound to improve the photovoltaic response in solar cells.

We describe a direct deposition method for the manufacture of 2D-colloidal crystal films on flexible substrates using a roll-to-roll technique (R2R). Suspensions of silica (SiO2) particles in ethanol with different concentrations and particle sizes (diameters between 150 nm and 520 nm) were prepared and directly deposited onto PET, ITO/PET and stainless steel substrates via wire-bar R2R. We propose an empirical equation that allows one to predict an optimal concentration of the colloidal suspension as a function of the processing parameters necessary to produce a colloidal monolayer. We argue that the development of a R2R coating technique for the fabrication of 2D nanostructures can overcome some technological obstacles that currently hinder the development of printed photonics, nanofabrication and colloidal lithography.

In this work, we investigated the influence of the mobility ( μ ) and the lifetime ( τ ) of charge carriers on the short-circuit current, the fill factor, and the efficiency of a bulk heterojunction solar cell based on a P3HT:PCBM biphasic film. Measurements of the photocurrent as a function of the applied voltage J ph ( V ), photo-CELIV, and the transient photovoltage (TPV) were carried out at different temperatures (100–340 K). With the help of an analytical model for the photocurrent, we shed light on which recombination mechanism is dominant along the J ph ( V ) curve and quantitatively evaluated the impact of the μτ product on the cell parameters. We conclude that for voltages close to the open-circuit voltage, nongeminate recombination is the main loss factor in a bulk heterojunction solar cell, while as the photocurrent approaches its saturated value, the loss factor is essentially defined by the dissociation probability ( P ) of the charge transfer states (CTC states). Thermomechanical analysis (DMA) provided additional information about structural changes of the P3HT:PCBM active layer, which can be correlated with changes in the loss factor and in the cell parameters.

When adjusting the pH of deposition baths, ammonia (NH 3 ) is often used instead of sodium hydroxide (NaOH), but its effects on the chemical and/or electrochemical processes are not usually considered. Here the influence of NH 3 on the deposition rate, composition and magnetic properties of amorphous cobalt-boron (CoB) alloys deposited from alkaline plating baths containing citrate is discussed. We have observed that when the pH of the solution was adjusted with NH 3 , CoB films were deposited at higher rates and the B content decreased with increasing pH. Opposite trends were observed when NaOH was used to adjust the bath pH. These observations were discussed in terms of the complex species distribution in solution and of the buffering characteristics of NH 3 . The reducing agent, dimethylaminoborane, has its electrooxidation also affected by the presence of NH 3 in solution. Amorphous, soft CoB magnetic films with coercivity values varying from 40 Oe to 80 Oe, inversely dependent on the B content of the film, were obtained.

Fabrication and optical characterization of Tm 3+ /Yb 3+ codoped PbO–GeO 2 (PGO) pedestal-type waveguides are investigated in this work. It is important to mention that, to the best of authors’ knowledge, the use of PGO pedestal-type waveguide has not been studied before. PGO thin films codoped with Tm 3+ and Yb 3+ were obtained through RF magnetron sputtering technique. The pedestal profile was obtained using conventional optical lithography procedures, followed by plasma etching and sputtering deposition. The profile of Tm 3+ /Yb 3+ codoped PGO waveguides was observed by means of Scanning Electron Microscopy (SEM) measurements. Also the infrared and infrared-to-visible frequency upconversion luminescences of Tm 3+ ions were measured exciting the samples with a cw 980 nm diode laser. Propagation losses around 11 dB/cm and 9 dB/cm were obtained at 630 and 1050 nm, respectively, for waveguides in the 20–100 μm width range. Single-mode propagation was observed for waveguides width up to 12 μm and 7 μm, at 1050 nm and 630 nm, respectively; larger waveguides width provided multi-mode propagation. The present results corroborate the possibility of using Tm 3+ /Yb 3+ codoped PGO thin films as active waveguide for photonic applications.

Polypyrrole (PPy) is a conducting polymer widely investigated for many purposes, including as an electroactive material in supercapacitors. In this work, we studied the electropolymerization of PPy using methyl orange as a template to obtain thin films of PPy hydro-sponges. The growth of the films was performed by cyclic voltammetry and potentiostatic steps coupled with a quartz crystal microbalance measuring changes in frequency and energy dissipation. We found that methyl orange does not have an impact on the electropolymerization process in addition to its role in determining the microfibrillar structure, resulting in microfibers with diameters ranging from 500 to 900 nm, which is larger than the microfibers obtained in the chemical route with methyl orange. Changes in frequency and energy dissipation indicated that the film growth is similar when 0.45, 0.50 or 0.6 V vs Ag/AgCl NaCl 3M is applied, However, the chronoamperometric measurements show a larger increase in current density for the highest potential, suggesting that the growth of microfibers increases the surface area, which is responsible for the higher current density. Measurement of roughness using Atomic Force Microscopy for different chronoamperometry durations confirmed the increase in surface area as more PPy hydro-sponge is electropolymerized. Supercapacitors were assembled using an electrode of PPy hydro-sponge electropolymerized onto stainless steel as a negative electrode and activated carbon as a positive one. The capacitance of the PPy hydro-sponge electrode was estimated to be approximately 100 F g−1, while the two-electrode cell achieved 17 F g−1 while operating at 0.1 A g−1.

The growing use of nanoparticles in a variety of applications calls for detailed studies of their toxicology, which in turn require understanding the interactions between nanoparticles and living cells. Since simulating the interaction with real cell membranes is rather complex, Langmuir monolayers (LMs) have been used to mimic the first barrier encountered by a nanoparticle as it approaches a biological membrane to assess molecular-level interactions. In this study, we show how oppositely charged gold nanoparticles (Au-NPs) interact with monolayers of the zwitterionic dipalmitoylphosphatidyl choline (DPPC) and negatively charged dipalmitoylphosphatidyl glycerol (DPPG). The monolayers were spread on subphases containing two concentrations of either negatively charged Au-NPs coated with citrate anions or positively charged Au-NPs functionalized with the cationic polyelectrolyte poly(allylamine hydrochloride) (PAH). For DPPG, electrostatic effects dominated which depended strongly on the NPs capping agent, being obviously larger for the positive nanoparticles. The in-plane elasticity for DPPG monolayers within the surface pressure range corresponding to real cell membranes increased with adsorption of positively charged NPs, but decreased with the negative ones. For the zwitterionic DPPC, on the other hand, significant effects only occurred for negatively charged NPs, including a decrease in elasticity. Therefore, it is concluded that the nature, namely the charge of the capping agents, is crucial for the interaction of charged NPs with the cell membrane. (c) 2013 Elsevier B.V. All rights reserved.

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) rede nBioNet (Brazil) This study shows the incorporation of ibuprofen, an anti-inflammatory drug, in Langmuir monolayers as cell membrane models. Significant effects were observed for dipalmitoyl phosphatidyl choline (DPPC) monolayers with relevant changes in the elasticity of the monolayer. Dipalmitoyl phosphatidyl glycerol (DPPG) monolayers were affected by small concentrations of ibuprofen, from 1 to 5 mol%. for both types of monolayer, ibuprofen could penetrate into the hydrophobic part of the monolayer, which was confirmed with polarization-modulated infrared reflection-absorption spectroscopy (PM-IRRAS). Brewster angle microscopy (BAM) images showed that ibuprofen prevents the formation of large domains of DPPC. the pharmacological action should occur primarily with penetration of ibuprofen via electrically neutral phospholipid headgroups of the membrane. (c) 2013 Elsevier B.V. All rights reserved. Univ São Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP, Brazil Universidade Federal de São Paulo, Inst Ciencias Ambientais Quim & Farmaceut, Diadema, SP, Brazil Universidade Federal de São Paulo, Inst Ciencias Ambientais Quim & Farmaceut, Diadema, SP, Brazil Web of Science

Because of its thermal and morphological stability and optical and electrical properties, tris(8-hydroxyquinoline) aluminum (Alq 3 ) is one of the most widely used electron transporting materials in organic light-emitting devices (OLEDs). The search for substitutes for this compound constitutes an important field of research in organic electronics. We report on a study of a new rare-earth tetrakis 8-hydroxyquinoline complex. Synthesis of tris complexes with rare-earth metals and 8-hydroxyquinoline resulted in unstable compounds. However, the inclusion of an additional quinoline group stabilized these compounds. Li[RE(q) 4 ] (where RE = La 3 + , Lu 3 + and Y 3 + and q = 8-hydroxyquinoline) were synthesized and then used as the electron-transporting and emitting layer in OLEDs. Thin films were deposited in a high-vacuum environment by thermal evaporation on quartz and silicon substrates. Optical characterization of the RE complexes revealed emission in the 510–525 nm range, the same as that observed for Alq 3 , while absorption was observed at wavelengths of 382 nm for the Y/La complexes and 388 nm for the Lu complex. The OLEDs were fabricated with an indium tin oxide layer (ITO) as the anode, ( N , N ′-bis (1-naphtyl)- N , N ′-diphenyl-1,1′-biphenyl-4,4′-diamine) NPB as the hole-transporting layer (25 nm), Li[RE(q) 4 ] as the electron-transporting and emitting layer (40 nm) and aluminum as the cathode (120 nm). The electroluminescence (EL) spectra showed a broad band from 520 to 540 nm and green-colored emission associated with the 8-hydroxyquinoline ligand. There was an interesting dependence of the maximum energy peak position and half-width of the emission band in the EL spectra on the atomic radius of the RE ion used. The best luminance for the OLEDs produced in this study was achieved with the Li[RE(q) 4 ] compound. The optical and electrical properties of this OLED were comparable to those of similar devices based on Alq 3 .

Transparent nanostructure ZnO:CeO 2 and ZnO thin films to use as solar protector were prepared by non-alkoxide sol–gel process and deposited on boronsilicate glass substrate by dip-coating technique and then heated at 300–500 °C. The films were characterized structurally, morphologically and optically by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission gun-scanning electron microscopy (FEG-SEM), scanning electron microscopy (SEM) and UV–Vis transmittance spectroscopy. The coatings presented high transparency in the visible region and excellent absorption in the UV. The band gap of the deposited films was estimated between 3.10 and 3.18 eV. Absorption of the films in the UV was increased by presence of cerium. The results suggest that the materials are promising candidates to use as coating solar protective.

The infrared absorption of polysiloxanes involves a strong band at around 1050 cm− 1, attributed to the antisymmetric vibration of siloxane bridges. The splitting of this band into two components is generally attributed to coupling between next-neighbor siloxane groups along the polysiloxane chain. From a quantitative analysis of the spectra of these materials, we find that this splitting is larger when the material is in thin-film form, and that the relative intensity of the two components is polarization dependent. We show that these effects are fully understandable in the theoretical framework of infrared absorption by thin films, and are related to long-range dipolar interactions responsible for the longitudinal–transverse splitting effect in crystalline materials. As a consequence, the polarization dependence of the infrared absorption observed for thin films does not appear to be associated with an orientational ordering in the film.

Liponucleosides may assist the anchoring of nucleic acid nitrogen bases into biological membranes for tailored nanobiotechnological applications. To this end precise knowledge about the biophysical and chemical details at the membrane surface is required. In this paper, we used Langmuir monolayers as simplified cell membrane models and studied the insertion of five lipidated nucleosides. These molecules varied in the type of the covalently attached lipid group, the nucleobase, and the number of hydrophobic moieties attached to the nucleoside. All five lipidated nucleosides were found to be surface-active and capable of forming stable monolayers. They could also be incorporated into dipalmitoylphosphatidylcholine (DPPC) monolayers, four of which induced expansion in the surface pressure isotherm and a decrease in the surface compression modulus of DPPC. In contrast, one nucleoside possessing three alkyl chain modifications formed very condensed monolayers and induced film condensation and an increase in the compression modulus for the DPPC monolayer, thus reflecting the importance of the ability of the nucleoside molecules to be arranged in a closely packed manner. The implications of these results lie on the possibility of tuning nucleic acid pairing by modifying structural characteristics of the liponucleosides.

Frutalin is a homotetrameric α-d-galactose (d-Gal)-binding lectin that activates natural killer cells in vitro and promotes leukocyte migration in vivo. Because lectins are potent lymphocyte stimulators, understanding the interactions that occur between them and cell surfaces can help to the action mechanisms involved in this process. In this paper, we present a detailed investigation of the interactions of frutalin with phospho- and glycolipids using Langmuir monolayers as biomembrane models. The results confirm the specificity of frutalin for d-Gal attached to a biomembrane. Adsorption of frutalin was more efficient for the galactose polar head lipids, in contrast to the one for sulfated galactose, in which a lag time is observed, indicating a rearrangement of the monolayer to incorporate the protein. Regarding ganglioside GM1 monolayers, lower quantities of the protein were adsorbed, probably due to the farther apart position of d-galactose from the interface. Binary mixtures containing galactocerebroside revealed small domains formed at high lipid packing in the presence of frutalin, suggesting that lectin induces the clusterization and the forming of domains in vitro, which may be a form of receptor internalization. This is the first experimental evidence of such lectin effect, and it may be useful to understand the mechanism of action of lectins at the molecular level.

Barium molybdate (BaMoO4) powders were synthesized by the co-precipitation method and processed in microwave-hydrothermal at 140 C for different times. These powders were characterized by X-ray diffraction (XRD), Fourier transform Raman (FT-Raman), Fourier transform infrared (FT-IR), ultraviolet–visible (UV–vis) absorption spectroscopies and photoluminescence (PL) measurements. XRD patterns and FT-Raman spectra showed that these powders present a scheelite-type tetragonal structure without the presence of deleterious phases. FT-IR spectra exhibited a large absorption band situated at around 850.4 cm � 1 , which is associated to the Mo–O antisymmetric stretching vibrations into the [MoO4] clusters. UV–vis absorption spectra indicated a reduction in the intermediary energy levels within band gap with the processing time evolution. First-principles quantum mechanical calculations based on the density functional theory were employed in order to understand the electronic structure (band structure and density of states) of this material. The powders when excited with different wavelengths (350 nm and 488 nm) presented variations. This phenomenon was explained through a model based in the presence of intermediary energy levels (deep and shallow holes) within the band gap.

Agradecimentos: One of the authors (E.A. Souza) thanks CAPES (Brazil) for financial support. Dr. Manfredo H. Tabacknicks (LAMFI, USP) is acknowledged for the RBS experiments. Drs. R. Landers and L.P. Cardoso (IFGW, UNICAMP) are acknowledged for the XPS and XRD experiments. The XANES experiments were performed at the Laboratório Nacional de Luz Síncrotron (LNLS, Campinas, Brazil) Abstract: Vanadium pentoxide is one of the most attractive cathodic materials for use in microbatteries. However, the continuous insertion and extraction of lithium ions generate gradative losses in its intercalation capacity during the charge and discharge cycles. The insertion of metallic ions in the oxide matrix, forming bronzes of general formula MexV2O5 is an alternative to increase the electrochemical performance of V2O5. In this work, vanadium oxides and bronzes, in thin film form, were deposited by means of co-sputtering. Structural, chemical and electrochemical characterizations were realized in order to identify the cristallinity, composition, density and oxidation states of the elements in the film. The electrochemical techniques were used for analysis of the reversibility, charge capacity and determination of the diffusion coefficient for lithium ions. The main conclusion is that the addition of copper increased the specific volumetric capacity of the thin films and a better performance was attained during the charge/discharge cycles COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Fechado