Ethanol electro-oxidation on carbon-supported Pt-Ru, Pt-Rh and Pt-Ru-Rh nanoparticles

This work investigates the effects of carbon-supported Pt, Pt-Ru, Pt-Rh and Pt-Ru-Rh alloy electrocatalysts oil the yields of CO2 and acetic acid as electro-oxidation products of ethanol. Electronic and structural features of these metal alloys were studied by in situ X-ray absorption spectroscopy (XAS). The electrochemical activity was investigated by polarization experiments and the reaction intermediates and products were analyzed by in situ Fourier Transform Infra-Red Spectroscopy (FTIR). Electrochemical stripping of CO. which is one of the adsorbed intermediates, presented a faster oxidation kinetics on the Pt-Ru electrocatalyst, and similar rates of reaction on Pt-Rh and Pt. The electrochemical current of ethanol oxidation showed a higher value and the onset potential was less positive oil Pt-Ru. However, in situ FTIR spectra evidenced that the CO2/acetic acid ratio is higher for the materials with Rh, mainly at lower potentials. These results indicate that the Ru atoms act mainly by providing oxygenated species for the oxidation of ethanol intermediates, and point out ail important role of Rh on the C-C bond dissociation. (C) 2007 Elsevier Ltd. All rights reserved.

Gelatin-based protonic electrolyte for electrochromic windows

Proton-conducting gel polymer electrolytes based on gelatin plasticized with glycerol and containing acetic acid were investigated, characterized, and applied to electrochromic window. For glycerol contents varying from 7% to 48%, the conductivity of the uniform and predominantly amorphous gel electrolyte was found to follow a Vogel-Tamman-Fulcher behavior with the temperature. Typically, for the electrolyte chosen to make 7 x 2 cm(2) electrochromic smart window with the configuration: glass/fluor-doped tin oxide (FTO)/WO(3)/gelatin electrolyte/CeO(2)-TiO(2)/FTO/glass and containing 28% of glycerol, the conductivities were found to be of the order of 5 x 10(-5) S/cm at room temperature and 3.6 x 10(-4) S/cm at 80 A degrees C. The device was characterized by spectroelectrochemical techniques and was tested up to 10,000 cycles showing a fast coloring/bleaching behavior, where the coloring process was achieved in 10 s and the bleaching in 2 s. The transmission variation at the wavelength of 550 nm was about 15%. The cyclic voltammograms showed a very good reversibility of the cathodic/anodic processes, and the charge density was about 3.5 mC/cm(2). The memory tests showed that the transmittance in the colored state increased by 8% in 90 min after removing the potential.

Agar-based films for application as polymer electrolytes

New types of polymer electrolytes based on agar have been prepared and characterized by impedance spectroscopy, X-ray diffraction measurements, UV-vis spectroscopy and scanning electronic microscopy (SEMI). The best ionic conductivity has been obtained for the samples containing a concentration of 50 wt.% of acetic acid. As a function of the temperature the ionic conductivity exhibits an Arrhenius behavior increasing from 1.1 x 10(-4) S/cm at room temperature to 9.6 x 10(-4) S/cm at 80 degrees C. All the samples showed more than 70% of transparency in the visible region of the electromagnetic spectrum, a very homogeneous surface and a predominantly amorphous structure. All these characteristics imply that these polymer electrolytes can be applied in electrochromic devices. (C) 2009 Elsevier Ltd. All rights reserved.

Optimization of performances of gelatin/LiBF(4)-based polymer electrolytes by plasticizing effects

Gelatin is a cheap and abundant natural product with very good biodegradation properties and can be used to obtain acetic acid or LiClO(4)-based gel polymer electrolytes (GPEs) with high ionic conductivity and good stability. This article presents results of GPEs obtained by the plasticization of gelatin and addition of LiBF(4), where the optimization of the system was achieved by using a factorial design type 22 with two variables: glycerol and LiBF(4). From this analysis it was stated that the effect of glycerol as a plasticizer on the ionic conductivity results is much more important than the effect obtained by varying the lithium salt content or the effect of the interaction of both variables. Also all the samples were characterized by X-ray diffraction measurements, UV-vis-NIR spectroscopy and scanning electron microscopy (SEM) and impedance spectroscopy. The ionic conductivity results of all analyzed samples as a function of temperature obey predominantly an Arrhenius relationship and the samples are stable up to 160 degrees C. Good conductivity results combined with transparency and good adhesion to the electrodes have shown that gelatin-based GPEs are very promising materials to be used as solid electrolytes in electrochromic devices. (C) 2009 Elsevier Ltd. All rights reserved.

Graphite-silicone rubber composite electrode: Preparation and possibilities of analytical application

Composite electrodes were prepared using graphite powder and silicone rubber in different compositions. The use of such hydrophopic materials interned to diminish the swallowing observed in other cases when the electrodes are used in aqueous solutions for a long time. The composite was characterized for the response reproducibility, ohmic resistance, thermal behavior and active area. The voltammetric response in relation to analytes with known voltammetric behavior was also evaluated, always in comparison with the glassy carbon. The 70% (graphite, w/w) composite electrode was used in the quantitative determination of hydroquinone (HQ) in a DPV procedure in which a detection limit of 5.1 x 10(-8) mol L-1 was observed. HQ was determined in a photographic developer sample with errors lower then 1% in relation to the label value. (c) 2007 Elsevier B.V. All rights reserved.

Volatile flavour constituent patterns of terras madeirenses red wines extracted by dynamic headspace solid‐phase microextraction

A suitable analytical procedure based on static headspace solid-phase microextraction (SPME) followed by thermal desorption gas chromatography–ion trap mass spectrometry detection (GC–ITDMS), was developed and applied for the qualitative and semi-quantitative analysis of volatile components of Portuguese Terras Madeirenses red wines. The headspace SPME method was optimised in terms of fibre coating, extraction time, and extraction temperature. The performance of three commercially available SPME fibres, viz. 100 lm polydimethylsiloxane; 85 lm polyacrylate, PA; and 50/30 lm divinylbenzene/carboxen on polydimethylsiloxane, was evaluated and compared. The highest amounts extracted, in terms of the maximum signal recorded for the total volatile composition, were obtained with a PA coating fibre at 308C during an extraction time of 60 min with a constant stirring at 750 rpm, after saturation of the sample with NaCl (30%, w/v). More than sixty volatile compounds, belonging to different biosynthetic pathways, have been identified, including fatty acid ethyl esters, higher alcohols, fatty acids, higher alcohol acetates, isoamyl esters, carbonyl compounds, and monoterpenols/C13-norisoprenoids.

Caracterização funcional de dois cDNAs homólogos à ciclofilina e à proteína reprimida por auxina (ARP) identificados em bibliotecas subtrativas a para floração em tomateiro

Flowering is a fundamental process in the life cycle for plant. This process is marked by vegetative to reproductive apical meristem conversion, due to interactions between several factors, both internal and external to plant. Therefore, eight subtractive libraries were constructed using apical meristem induced or not induced for two contrasting species: Solanum lycopersicum cv. Micro-Tom and Solanum pimpinellifolium. Several cDNAs were identified and among these, were selected two cDNAs: one homologous cDNA to cyclophilin (LeCYP1) and the other to Auxin repressed protein (ARP). It has observed that LeCYP1 and ARP genes are important in the developmental process to plants. In silico analysis, were used several databases with the exclusion criterion E-value <1.0x10-15. As a result, conservation was observed for proteins analyzed by means of multiple alignments and the presence of functional domains. Then, overexpression cassettes were constructed for the ARP cDNA in sense and antisense orientations. For this step, it was used the CaMV35S promoter. The cDNA orientation (sense or antisense) in relation to the promoter was determined by restriction enzymes and sequencing. Then, this cassette was transferred to binary vector pZP211 and these cassettes were transferred into Agrobacterium tumefaciens LBA4404. S. lycopersicum cv. Micro-Tom (MT) and MT-Rg1 plants were transformed. In addition, seedlings were subjected to hormone treatments using a synthetic auxin (- naphthalene acetic acid) and cyclosporin A (cyclophilin inhibitor) treatments and it was found that the hormone treatment there were changes in development of lateral roots pattern, probably related to decreases in auxin signaling caused by reduction of LeCYP1 in MT-dgt plants while cyclosporin A treatments, there was a slight delay in flowering in cv. MT plants. Furthermore, assay with real-time PCR (RT-qPCR) were done for expression level analysis from LeCYP1 and ARP in order to functionally characterize these sequences in tomato plants.

Obtenção de polímeros de LCC para aplicação como antioxidante de biodiesel de soja

Biodiesel is a fuel obtained from vegetable oils, such as soy, castorbean, among others. The monoester of fatty acid of these oils have chains with mono, di and tri double connections. The presence of these insaturations are susceptible to oxidization. Antioxidants are substances able to prevent oxidization from oils, fats, fat foods, as well as esters of Alquila( biodiesel). The objective of this work is to summarize a new antioxidant from the Cashew Nut Shell Liquid (CNSL) using the electrolysis technique. A current of 2 amperes was used in a single cell of only one group and two eletrodos of stainless steel 304 in a solution of methanol, together with the eletrolits: acetic acid, sodium chloride and sodium hydroxide, for two hours of agitation. The electrolysis products are characterized by the techniques of cromatography in a thin layer, spectroscopy of infrared and gravimetric analysis. The material was submitted to tests of oxidative stability made by the techniques of spectropy of impendancy and Rancimat (EN 14112). The analyses of characterization suggest that the polimerization of the electrolytic material ocurred. The application results of these materials as antioxidants of soy biodiesel showed that the order of the oxidative stability was obtained by both techniques used

Aditivos químicos e biológicos na ensilagem de cana-de-açúcar: 1. composição química das silagens, ingestão, digestibilidade e comportamento ingestivo

Avaliou-se o efeito da inclusão de aditivos na ensilagem de cana-de-açúcar (Saccharum officinarum L.) sobre a composição químico-bromatológica das silagens, o comportamento ingestivo, o consumo voluntário e a digestibilidade em bovinos de corte. Utilizaram-se cinco novilhos da raça Nelore providos de cânula ruminal, alocados em delineamento quadrado latino 5 ´ 5 e alimentados com dietas com 65% de volumoso na MS. Foram avaliadas cinco silagens (base úmida): controle - cana-de-açúcar sem aditivos; uréia - cana-de-açúcar + 0,5% uréia; benzoato - cana-de-açúcar + 0,1% de benzoato de sódio; LP - cana-de-açúcar inoculada com Lactobacillus plantarum (1 ´ 10(6) ufc/g MV); LB - cana-de-açúcar inoculada com L. buchneri (3,6 ´ 10(5) ufc/g forragem). A forragem foi armazenada em silos do tipo poço por 90 dias antes do fornecimento aos animais. A composição químico-bromatológica da cana-de-açúcar foi alterada após a ensilagem, em relação à cana-de-açúcar original, com redução no teor de carboidratos solúveis e na digestibilidade in vitro e elevação relativa nos teores de FDN e FDA. Os teores de etanol (0,30% da MS) e ácidos orgânicos (0,99% de ácido lático e 2,31% de acético) foram baixos e semelhantes entre as silagens. Os aditivos aplicados na ensilagem não promoveram alterações no consumo e na digestibilidade aparente da MS (7,2 kg/dia e 63,6%, respectivamente). O comportamento ingestivo dos animais também não foi alterado, com tempos médios de 230,6; 519,6 e 672,8 minutos/dia despendidos com ingestão de ração, ruminação e ócio, respectivamente. Os aditivos acrescidos à cana-de-açúcar promoveram pequenas alterações na maioria das variáveis avaliadas.

Preferential location of lidocaine and etidocaine in lecithin bilayers as determined by EPR, fluorescence and H-2 NMR

We have examined the effect of the uncharged species of lidocaine (LDC) and etidocaine (EDC) on the acyl chain moiety of egg phosphatidylcholine liposomes. Changes in membrane organization caused by both anesthetics were detected through the use of EPR spin labels (5, 7 and 12 doxyl stearic acid methyl ester) or fluorescence probes (4, 6, 10, 16 pyrene-fatty acids). The disturbance caused by the LA was greater when the probes were inserted in more external positions of the acyl chain and decreased towards the hydrophobic core of the membrane. The results indicate a preferential insertion of LDC at the polar interface of the bilayer and in the first half of the acyl chain, for EDC. Additionally, 2 H NMR spectra of multilamellar liposomes composed by acyl chain-perdeutero DMPC and EPC (1:4 mol%) allowed the determination of the segmental order (S-mol) and dynamics (T-1) of the acyl chain region. In accordance to the fluorescence and EPR results, changes in molecular orientation and dynamics are more prominent if the LA preferential location is more superficial, as for LDC while EDC seems to organize the acyl chain region between carbons 2-8, which is indicative of its positioning. We propose that the preferential location of LDC and EDC inside the bilayers creates a "transient site", which is related to the anesthetic potency since it could modulate the access of these molecules to their binding site(s) in the voltage-gated sodium channel. (C) 2007 Elsevier B.V. All rights reserved.

Avaliação de diferentes formas de preservação e desenvolvimento in situ de folículos ovarianos pré-antrais caprinos

This study evaluated the effect of indole-3-acetic acid (IAA) in the activation of goats preantral follicles (FOPA). Were used four pairs of ovaries of adult mixed breed goats. Each ovarian pair was divided into 23 fragments. One fragment was fixed for histology and other fragment was using to follicular isolation procedure. The remaining fragments were cultured in 1.0 ml of Minimum Essential Medium (MEM) or MEM supplemented with IAA at concentrations of 10, 40, 100, 500 or 1000 ng/mL. The in vitro culture was performed at 39°C in incubator with 5% CO2 for 1, 3 and 5 days. After in vitro culture was evaluated histological integrity and viability of FOPA. The addition of 100 ng/ml of IAA to MEM showed a significant increase in follicles transition in the third day of in vitro culture, characterizing follicular activation. Moreover, this concentration was obtained maintaining the histological integrity of PAF by the fifth day of in vitro culture. The viability test confirmed the results of histology. Thus, we conclude that IAA can promote the activation of goats FOPA

Biological and structural characterization of a new PLA(2) from the Crotalus durissus collilineatus venom

In the present article we report on the biological characterization and amino acid sequence of a new basic Phospholipases A(2) (PLA(2)) isolated from the Crotalus durissus collilineatus venom (Cdcolli F6), which showed the presence of 122 amino acid residues with a pI value of 8.3, molecular mass of 14 kDa and revealed an amino acid sequence identity of 80% with crotalic PLA(2)s such as Mojave B, Cdt F15, and CROATOX. This homology, however, dropped to 50% if compared to other sources of PLA(2)s such as from the Bothrops snake venom. Also, this PLA(2) induced myonecrosis, although this effect was lower than that of BthTx-I or whole crotoxin and it was able to induce a strong blockage effect on the chick biventer neuromuscular preparation, independently of the presence of the acid subunid (crotapotin). The neurotoxic effect was strongly reduced by pre-incubation with heparin or with anhydrous acetic acid and rho-BPB showed a similar reduction. The rho-BPB did not reduce significantly the myotoxic activity induced by the PLA(2), but the anhydrous acetic acid treatment and the pre-incu-bation of PLA(2) with heparin reduced significantly its effects. This protein showed a strong antimicrobial activity against Xanthomonas axonopodis passiflorae (Gram-negative), which was drastically reduced by incubation of this PLA(2) with rho-BPB, but this effect was marginally reduced after treatment with anhydrous acetic acid. Our findings here allow to speculate that basic amino acid residues on the C-terminal and molecular regions near catalytic site regions such as Calcium binding loop or rho-wing region may be involved in the binding of this PLA(2) to the molecular receptor to induce the neurotoxic effect. The bactericidal effect, however, was completely dependent on the enzymatic activity of this protein.

Desenvolvimento e validação de método analítico para determinação de WE010, WE014 e WE017

The synthetic guanylhydrazones WE010 (3,5-di-tert-butil-4-hidroxibenzaldehyde-guanylhydrazone), WE014 (4-bifenilcarboxialdehydeguanylhydrazone) and WE017 (3,4-diclorobenzaldehydeguanylhydrazone) showed high cytotoxic activity in terms of percentage inhibition of cancer cells growth. However, further progress in the development of these drug candidates requires precise and convenient methods for their qualitative and quantitative analyses. The aim of this study was to develop and validate High Performance Liquid Chromatography with diode-array detection (HPLC-DAD) and Ultra Fast Liquid Chromatography with diode-array detection (UFLC-DAD) methods suitable for as simultaneous as isolated determination of studied guanylhydrazones, based on the optimization of chromatographic parameters and obtaining reduced detection times. The chromatographic analyses of analytes by HPLC were performed on C18 ACE analytical column (150 mm x 4.6 mm), with a particle size of 5.0 μm. Among all the conditions assayed, the best results of separation were obtained with a mixture of methanol:water (60:40, v/v) as the mobile phase at a flow rate 1.5mL/min and pH of 3.5 adjusted at acetic acid. The UFLC method was developed by experimetal desing techniques in order to find optimal chromatographic analytical conditions, which were achieved on XR-ODS analytical column (50 mm x 3.0 mm), with a particle size of 2,2 μm, maintained at 25 ºC. The mobile phase was consisted of methanol:water (65:35, v/v) with 0.1% triethylamine (TEA) and pH of 3.5 adjusted at acetic acid, at a flow rate 0.5 mL/min. The procedure were validated following evaluating parameters such as specificity, linearity, limits of detection (LD) and quantification (LQ), precision, accuracy and robustness, giving results within the acceptable range. Although the UFLC method shows better sensitivity (lower values of LD and LQ), robustness (lower rates of relative standard deviation) and minimize spending time and solvent, both developed methods were adequately applied to the analysis of guanylhydrazones molecules, may be used in routine of quality control laboratories. Keywords: guanylhydrazones, HPLC/DAD, UFLC/DAD, validation of analitical method

Desbaste da limeira-ácida-'Tahiti' (Citrus latifolia Tanaka) com TPA e efeitos na produção

Foram avaliadas concentrações de 0; 10; 20; 40 e 80 mg/L do 3,5,6-TPA (Ácid 3,5,6-tricloro-2-piridil- oxiacético), em sua formulação éster, para desbaste de frutos novos da limeira-ácida-'Tahiti' (Citrus latifolia Tanaka), nas condições ecológicas do Estado de São Paulo. O 3,5,6-TPA, na concentração 10mg/L, foi o tratamento mais eficaz para uso na cultura. Concentrações maiores causaram severos danos às plantas. Essa concentração, aplicada logo após a florada de outubro, reduziu em 65% a produção do mês de fevereiro seguinte. Todavia, as produções dos meses subseqüentes não diferiram entre si. A concentração de 10mg/L causou alongamento dos frutos, aumento da espessura da casca e redução do Brix, na época da colheita.

Induction of somatic embryogenesis in soybean: physicochemical factors influencing the development of somatic embryos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)