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Resumo A injustiça epistêmica agencial no processo penal ocorre quando se imputa excessiva credibilidade a declarações prestadas pelo locutor em momentos de reduzida capacidade de autodeterminação. Especificamente no contexto da retratação de confissões extrajudiciais, questiona-se quais critérios jurídicos de valoração probatória racional seriam capazes de prevenir a ocorrência de injustiças agenciais. A metodologia empregada foi a pesquisa bibliográfica em injustiça epistêmica, confiabilidade probatória da confissão e precedentes do Superior Tribunal de Justiça. Analisando estudos empíricos sobre falsas confissões e as práticas forenses brasileiras, constata-se um risco relevante de ocorrência dessa forma de injustiça, tendo em vista que confissões extrajudiciais são largamente utilizadas para fundamentar sentenças condenatórias. O artigo conclui com duas propostas: (I) desconsiderar, para fins de valoração da prova, confissões extrajudiciais não confirmadas em juízo; e (II) adotar como um dos critérios de valoração da confissão o grau de efetiva agência epistêmica do acusado ao confessar, atribuindo-se menor credibilidade às confissões obtidas em situações de agência reduzida. Abstract Agential epistemic injustice in criminal prosecution occurs when declarations taken in moments of reduced capacity for self-determination receive excessive credibility. Specifically in the context of recanted out-of-court confessions, the article investigates which legal criteria for the rational evaluation of evidence could prevent agential injustices. The method employed was bibliographical research on epistemic injustice, reliability of confessions as criminal evidence, and the Superior Court of Justice’s case law. Analyzing empiric research on false confessions and forensic practices in Brazil, a significant risk for agential injustices can be detected, mainly because out-of-court confessions are largely used to justify criminal convictions. The article concludes with two propositions: (I) to disregard, during the evaluation of evidence, out-of-court confessions not repeated before a judge; and (II) to consider the level of the defendant’s effective epistemic agency when evaluating their confession, with less credibility given to confessions obtained in situations of reduced agency.

Pretende o presente trabalho analisar as atividades de investigação defensiva, abordando a partir dos precursores do tema até a materialidade de disposições normativas a respeito, trazendo seus contornos doutrinários e práticos. Além do mais, almeja o presente trabalho analisar e destacar a importância do assunto, principalmente seus aspectos contributivos para melhor instrução do processo acusatório, desde sua fase preliminar até sua aplicação na última fase da persecução penal. Inclusive, o resultado da pesquisa sobre a matéria objeto do presente trabalho científico revelará a importância da aplicação da investigação defensiva em prol de uma persecução penal que seja a mais justa possível.

The study aimed to identify interspecies interactions within a native microbial community present in a hydrogen-producing bioreactor fed with two wheat straw cultivars. The relationships between the microbial community members were studied building a canonical correspondence analysis and corroborated through in vitro assays. The results showed that the bioreactor reached a stable hydrogen production of ca. 86 mL/kg·d in which the cultivar change did not affect the average performance. Lactobacillus and Clostridium dominated throughout the whole operation period where butyric acid was the main metabolite. A canonical correspondence analysis correlated positively Lactobacillus with hydrogen productivity and hydrogen-producing bacteria like Clostridium and Ruminococaceae. Agar diffusion testing of isolated strains confirmed that Lactobacillus inhibited the growth of Enterococcus, but not of Clostridium. We suggest that the positive interaction between Lactobacillus and Clostridium is generated by a division of labor for degrading the lignocellulosic substrate in which Lactobacillus produces lactic acid from the sugar fermentation while Clostridium quickly uses this lactic acid to produce hydrogen and butyric acid. The significance of this work lies in the fact that different methodological approaches confirm a positive association in the duo Lactobacillus–Clostridium in a bioreactor with stable hydrogen production from a complex substrate. HIGHLIGHTS Native microbiota of wheat straw reached a stable hydrogen production.; Microbial structure was stable dominated by Lactobacillus and Clostridium.; Statistical analysis and in vitro assays demonstrated positive interactions.; Division of labor in lignocellulose consumption could promote positive interactions.

Texto de autoria de Ministro do Superior Tribunal de Justiça. Submitted by betanial@stj.jus.br (betanial@stj.jus.br) on 2022-02-21T17:13:22Z No. of bitstreams: 2 teoria_mandados_criminalizacao_dantas.pdf: 4570086 bytes, checksum: 3e2039891a183c74ec0579837e65b332 (MD5) license.txt: 1239 bytes, checksum: c9b4c351324448672315a00808efb725 (MD5) Approved for entry into archive by Stephanie Moira (rsmoira@stj.jus.br) on 2022-03-10T18:40:18Z (GMT) No. of bitstreams: 2 teoria_mandados_criminalizacao_dantas.pdf: 4570086 bytes, checksum: 3e2039891a183c74ec0579837e65b332 (MD5) license.txt: 1239 bytes, checksum: c9b4c351324448672315a00808efb725 (MD5) Made available in DSpace on 2022-03-10T18:40:18Z (GMT). No. of bitstreams: 2 teoria_mandados_criminalizacao_dantas.pdf: 4570086 bytes, checksum: 3e2039891a183c74ec0579837e65b332 (MD5) license.txt: 1239 bytes, checksum: c9b4c351324448672315a00808efb725 (MD5) Previous issue date: 2022

Human lifestyle and its relationship with the human microbiome has been a line of research widely studied. This is because, throughout human history, civilizations have experienced different environments and lifestyles that could have promoted changes in the human microbiome. The comparison between industrialized and non-industrialized human populations in several studies has allowed to observe variation in the microbiome structure due to the population lifestyle. Nevertheless, the lifestyle of human populations is a gradient where several subcategories can be described. Yet, it is not known how these different lifestyles of human populations affect the microbiome structure on a large scale. Therefore, the main goal of this work was the collection and comparison of 16S data from the gut microbiome of populations that have different lifestyles around the world. With the data obtained from 14 studies, it was possible to compare the gut microbiome of 568 individuals that represent populations of hunter-gatherers, agricultural, agropastoral, pastoral, and urban populations. Results showed that industrialized populations present less diversity than those from non-industrialized populations, as has been described before. However, by separating traditional populations into different categories, we were able to observe patterns that cannot be appreciated by encompassing the different traditional lifestyles in a single category. In this sense, we could confirm that different lifestyles exhibit distinct alpha and beta diversity. In particular, the gut microbiome of pastoral and agropastoral populations seems to be more similar to those of urban populations according to beta diversity analysis. Beyond that, beta diversity analyses revealed that bacterial composition reflects the different lifestyles, representing a transition from hunters-gatherers to industrialized populations. Also, we found that certain groups such as Bacteoidaceae, Lanchospiraceae, and Rickenellaceae have been favored in the transition to modern societies, being differentially abundant in urban populations. Thus, we could hypothesize that due to adaptive/ecological processes; multifunctional bacterial groups (e.g., Bacteroidaceae) could be replacing some functions lost in the transition to modern lifestyle.

O presente artigo propõe a compreensão do que são grupos de pressão e como esses grupos agem ao influenciar o processo legislativo no Brasil e no mundo, explorando, ainda, o recorte social e jurídico da efetividade de sua ação, no que concerne à legislação criminal vigente no país. Nesse sentido, é indispensável esclarecer que o Direito Penal se orienta, quando da produção legislativa, em conformidade com uma (pre)suposta racionalidade relacionada, ex ante, a interesses setoriais. This article proposes an understanding of what pressure groups are and how these groups act to influence the legislative process in Brazil and in the world, also exploring the social and legal framework of the effectiveness of their action, with regard to the criminal legislation in force in the country. In this sense, it is essential to clarify that the Criminal Law is oriented, when producing legislation, in accordance with a (supposed) rationality related, ex ante, to sectorial interests.

This paper presents the first slicing approach for probabilistic programs based on specifications. We show that when probabilistic programs are accompanied by their specifications in the form of pre- and post-condition, we can exploit this semantic information to produce specification-preserving slices strictly more precise than slices yielded by conventional techniques based on data/control dependency. To achieve this goal, our technique is based on the backward propagation of post-conditions via the greatest pre-expectation transformer -- the probabilistic counterpart of Dijkstra weakest pre-condition transformer. The technique is termination-sensitive, allowing to preserve the partial as well as the total correctness of probabilistic programs w.r.t. their specifications. It is modular, featuring a local reasoning principle, and is formally proved correct. As fundamental technical ingredients of our technique, we design and prove sound verification condition generators for establishing the partial and total correctness of probabilistic programs, which are of interest on their own and can be exploited elsewhere for other purposes. On the practical side, we demonstrate the applicability of our approach by means of a few illustrative examples and a case study from the probabilistic modelling field. We also describe an algorithm for computing least slices among the space of slices derived by our technique.

The rhizosphere provides several benefits to the plant host being a strong determinant for its health, growth and productivity. Nonetheless, the factors behind the assembly of the microbial communities associated with the rhizosphere such as the role of plant genotypes are not completely understood. In this study, we tested the role that intraspecific genetic variation has in rhizospheric microbial community assemblages, using genetically distinct wild cotton populations as a model of study. We followed a common garden experiment including five wild cotton populations, controlling for plant genotypes, environmental conditions and soil microbial community inoculum, to test for microbial differences associated with genetic variation of the plant hosts. Microbial communities of the treatments were characterized by culture-independent 16S rRNA gene amplicon sequencing with Illumina MiSeq platform. We analyzed microbial community diversity (alpha and beta), and diversity structure of such communities, determined by co-occurrence networks. Results show that different plant genotypes select for different and specific microbial communities from a common inoculum. Although we found common amplicon sequence variants (ASVs) to all plant populations (235), we also found unique ASVs for different populations that could be related to potential functional role of such ASVs in the rhizosphere.

Made available in DSpace on 2020-12-10T17:39:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-08-04 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) FINEP FAPEAL (Alagoas State Research Agency) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Environmental conditions have a profound effect on the photophysical behavior of highly conjugated compounds, which can be exploited in a large variety of applications. In this context, we use a combination of experimental and computational methods to investigate thermal and solvatochromic effects on the fluorescence properties of a dansyl derivative bearing a thienyl substituent, namely 2-(3-thienyl)ethyl dansylglycinate (TEDG). In particular, we analyze how the solvent polarity and temperature affect the ground and excited state energies of TEDG by using time-resolved and steady-state fluorescence techniques. We determine the changes in dipole moment of the TEDG molecule upon photoexcitation, as well as the solvent polarity effects on the excited state lifetime. Besides, we provide theoretical modeling of the HOMO-LUMO orbitals and the vertical absorption and emission energies using time-dependent density functional theory (TDDFT) as well as the polarizable continuum model (PCM) to include the solvent contribution to the absorption and emission energies. Our results show that the emission mechanism of TEDG involves locally excited states derived from hybrid molecular orbitals, accompanied by a moderate variation of the molecular dipole moment upon light excitation. Our findings demonstrate that TEDG exhibits desirable fluorescence properties that make it a promising candidate for use as a photoactive material in electrochromic, optical thermometry, and thermography applications. Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Fis, BR-14040901 Ribeirao Preto, SP, Brazil Univ Estadual Paulista, Fac Ciencias & Tecnol, Dept Fis, BR-19060900 Presidente Prudente, SP, Brazil Univ Fed Alagoas, Inst Quim & Biotecnol, BR-57072970 Maceio, Alagoas, Brazil Univ Fed Alagoas, Inst Fis, BR-57072970 Maceio, Alagoas, Brazil Univ Fed Pernambuco, Dept Quim Fundamental, CCEN, BR-50670901 Recife, PE, Brazil Inst Fed Piaui, Campus Angical, BR-64410000 Angical, PI, Brazil Univ Estadual Paulista, Fac Ciencias & Tecnol, Dept Fis, BR-19060900 Presidente Prudente, SP, Brazil CNPq: 438198/2018-2 CNPq: 305771/2016-7

This article is part of the comparative studies on organization and curriculum development, in the area of ​​Mathematical Education, in Brazil, Chile and Mexico. The intention is to highlight the impacts of the research results in Mathematics Education in the official documents of these countries, elaborated from the 90s of the 20th century and present similarities and differences of the Prescribed Mathematics Curricula. It was used as a path from the curricular comparison to the Comparative Education of documents that prescribe the educational systems and the Mathematics Curricula of basic education. The comparative analysis points out a differentiation in the curricular structure, an emphasis on algebra in the Chilean and Mexican curriculum and similarity as the use of problem solving in the teaching and learning process in the three countries. Este artigo insere-se no contexto dos estudos comparativos sobre organização e desenvolvimento curricular, na área de Educação Matemática, no Brasil, Chile e México. A intenção é evidenciar os impactos dos resultados de pesquisa em Educação Matemática nos documentos oficiais desses países, elaborados a partir dos anos 90 do século XX e apresentar semelhanças e diferenças dos Currículos Prescritos de Matemática. Utilizou-se como percurso da comparação curricular a Educação Comparada de documentos que prescrevem os sistemas educacionais e os Currículos de Matemática da educação básica. Na análise comparativa aponta-se uma diferenciação na estruturação curricular, ênfase da álgebra no currículo chileno e mexicano e semelhança como o uso da resolução de problema no processo de ensino e aprendizagem nos três países.

The use of commercial graphite powders (different sources and particle sizes), as electrode materials, was evaluated in an electrochemical cavity cell. The graphite powders were characterized by electron microscopy, XRD, vibrational spectroscopy, porosimetry, contact angle, Boehm titration and cyclic voltammetry. Despite similarities, the graphite powders differed significantly in terms of surface functional groups (SFGs), hydrophobicity and particle size. The surface chemistry of both graphites was modified by HCl treatment, followed by 200 °C heating, prior to electrode fabrication, which was found to play an important role on the electrode performance. Cyclic voltammetries were carried out for the two different graphites in acid medium and absence of reagent, and the results were correlated to Boehm titration, showing evidences of the presence of acidic and basic SFGs. After HCl + heat treatment, it was observed the diminishing of the SFGs for both commercial graphite powders tested. The electro-reduction of benzyl bromide was used as standard reaction, yielding 1,2-diphenylethane and toluene as products. A 23 factorial design was used to optimize some electrode parameters. The compaction of the graphite electrodes showed to be fundamental for obtaining good results. HCl + heat treatment favored the 1-electron process, giving 1,2‑diphenylethane as major product on both electrodes (GF, 61% and GA, 52%). The absence of graphite powder treatment favored the 2-electron process, furnishing toluene as major product (GF, 55% and GA, 43%).

The optimum conditions for the electrocatalytic hydrogenation of (R)-(+)-pulegone in water, using ultrasound (continuous or pulsed mode) and a nickel sacrificial anode have been determined. The continuous ultrasound (14 W), without temperature control, showed to be a most effective technique if compared with pulses of 0.2 s applied after each second. The sonication of the reaction solution presented a slight stereochemical effect on the product distribution, and its magnitude depends on both the ultrasound power and the mode. Simultaneous ultrasound irradiation during electrochemical process showed a synergetic effect, able to generate H radical from water H O bond rupture, in addition to the H radicals formed by the electrochemical reduction of water on the electrode surface, increasing both current efficiency and conversion yields. Chitosan microspheres were use in the removal of nickel ions of the aqueous medium showing an adsorption efficiency of 64%.

An electrochemical approach has been used for the aqueous synthesis of low-toxicity and eco-friendly copper indium sulfide (CuInS2) nanocrystals, and related core@shell systems (CuInS2@ZnX, where X = S2- and Se2-). The chalcogenide precursors (S2-, Se2-) were generated in electrochemical cavity cell, using a constant current electrolysis (i = 30 mA and Q = 11.5C), in the presence of metallic precursors (In3+, Cu+, Zn2+), room temperature and argon atmosphere. Firstly, In2S3 seeds were obtained in the intermediate compartment of the cell and converted to CuInS2 by thermoactivated diffusion (colloidal solution under reflux) of Cu+ ions into the In2S3 lattice. Cu+/In3+ ratios = 0.25 and 0.125 were tested for the production of CuInS2 stabilized by l -glutathione (GSH), and characterized by UV–vis and emission spectroscopy, XRD, HRTEM and zeta potential. CuInS2@ZnX nanoparticles were prepared by using the same electrochemical system, paired electrolysis and Zn sacrificial anode. Nanocrystals prepared under Cu+/In3+ = 0.125 reached 3.1% (CuInS2), 4.6% (CuInS2@ZnSe), and 9.6% (CuInS2@ZnS) quantum yields. The CuInS2@ZnX systems presented high cell viability (85%–94%) and internalization in cytosol region of HeLa cells, showing high potential for biological labeling.

In this work, ultrasound-assisted electrocatalytic hydrogenation (US-ECHSA) of safrole was carried out in water medium, using sacrificial anode of nickel. The ultrasonic irradiation was carried out at frequency of 20 kHz ± 500 Hz with a titanium cylindrical horn (MS 73 microtip; Ti-6AI-4V alloy; 3.0 mm diameter). The optimal conditions were analyzed by statistical experimental design (fractional factorial). The influence of the sonoelectrochemical reactor design was also investigated by using computational fluid dynamics as simulation tool. Among the five parameters studied: catalyst type, use of β-cyclodextrin as inverse phase transfer catalyst, sonoelectrochemical reactor design, ultrasound mode and the temperature of the solution, only the last three were significant. The hydrogenation product, dihydrosafrole, reached 94% yield, depending on the experimental conditions applied. Data of computational fluid dynamics showed that a wing shape tube added to the sonoelectrochemical reactor can work as a cooling apparatus, during the electrochemical process. The reactional solution temperature diminishes 14 °C when compared to the four-way-type reactor. Cooper cathode, absence of β-cyclodextrin, four-way-type reactor, ultrasound continuous mode (14 W) and absence of temperature control were the most effective reaction parameters for the safrole hydrogenation using US-ECHSA method. The proposed approach represents an important contribution for understanding the hydrodynamic behavior of sonoelectrochemical reactors designs and, consequently, for the reducing of the experimental costs inherent to the sonoelectrochemical process.

Mosquito-borne arboviruses compromise human health worldwide. Due to resistance to chemical insecticides, natural compounds have been studied to combat mosquitoes. Previous works have demonstrated a larvicidal activity of the water-soluble Moringa oleifera lectin (WSMoL) against Aedes aegypti, suggesting a mechanism of action based on the interaction between lectin and chitin present in the larvae’s peritrophic matrix. In this work, it was investigated the WSMoL activity against Aedes aegypti larvae, by using luminescent bioconjugates of WSMoL conjugated to l -glutathione capped CdTe quantum dots. The conjugation was confirmed by ITC experiments, presenting high enthalpy associated to hydrogen bond interactions between nanoparticles and lectins. The bioconjugate luminescence stability was evaluated by the quantum yield (QY) at different pHs, ionic strengths and heat treatment time. The best parameters reached were pH 7.0, absence of electrolytes and heat treatment, giving QY = 4.4 %. The larvae were exposed to the bioconjugates and analyzed by confocal and fluorescence microscopy. CdTe-WSMol were detected along the entire midgut tract, suggesting a strong interaction with peritrophic matrix and lumen of the Aedes aegypti.

O presente trabalho trata-se de resultados de um estudo comparativo dos Currículos prescritos de Matemática dos sistemas educativos de Brasil e México, porém, mais especificamente do Ensino Médio no Brasil e do Ensino Médio Superior no México. A análise comparativa buscou-se sinalizar as possíveis influências da Educação Matemática nos documentos oficias que regem os sistemas educacionais dos países comparados, como os Parâmetros Curriculares Nacionais de Matemática no Brasil e os Programas de Estudos das Matemáticas no México, e constata-se certas similaridades e diferenças no sistema de ensino dos países comparados. As considerações do estudo indicam que as influências da Educação Matemática nos Currículos prescritos estão presentes, como, Didática da Matemática francesa, Interdisciplinaridade, Contextualização, Resolução de Problemas, Modelagem Matemática, uso da História da Matemática e de recursos tecnológicos.

Este artículo tiene el objetivo de indicar, por medio de la metodología de la Educación Comparada, las tendencias didácticas y metodológicas para la enseñanza de Matemáticas en la Enseñanza Fundamental o equivalente de Brasil, Chile y México. Los análisis comparativos se dieron por dos motivos: cambios y reformas curriculares que ocurrieron en la transición del milenio en países latinoamericanos y que los países comparados son miembros de la FISEM - Federación Iberoamericana de Sociedades de Educación Matemática. Por lo tanto, se buscó en los Currículos prescritos de Matemáticas indicaciones de tales tendencias, siendo ellas, la resolución de problemas, la contextualización, la utilización de la historia de las Matemáticas, la tecnología y los juegos.

Este texto, que é um fragmento de uma tese da área da Educação Matemática, tem o propósito de trazer as visões de brasileiros e mexicanos sobre Currículos de Matemática. Nele trata-se as referências de Currículos, e busca-se, utilizando entrevistas, às visões de professores pesquisadores em Educação Matemática que trabalharam na organização e implementação de Currículos, de autores de livros, de formadores de professores de Matemática e de professores que ensinam Matemática. Conclui-se que os brasileiros e mexicanos entrevistados têm visões similares de Currículo de Matemática, e que os Currículos devem ser dinâmicos, atendendo os anseios das culturas locais e respeitando suas diversidades. Palavras-chave: Currículos. Currículos de Matemática. Brasil e México.

Ammonium N-(3,5-dinitrobenzoyl)-α-phenylglycinate adducts were synthesized and characterized by using different protonated amines as counter-ion: NH4+, (CH3–CH2–)2NH2+, (CH3–CH2–CH2)NH3+, (CH3–CH2–CH2–CH2–)NH3+ and (CH3–CH2–)3NH+. A photochemical process was observed under ultraviolet (λexc, 254 nm) or solar irradiation, both in solid state and in solution: DMSO, acetone or acetonitrile. 3,5-Dinitrobenzene and carboxylate groups, separated by an N-benzylamide bridge, are present in these adducts, acting as electron acceptor and electron donor, respectively. Spectroscopic analyses (NMR, IR and UV–vis) suggest a photoinduced intramolecular electron transfer. A first-order photochemical kinetics was proposed in DMSO/(n-propylammonium N-(3,5-dinitrobenzoyl)-α-phenylglycinate) solution; such behavior was similar for all adducts studied, probably due to total salt dissociation in solution. In the solid state, however, electron transfer process efficiency is directly proportional to Lewis base (amine) strength of the adduct counter-ion. Decarboxylation is observed after the irradiation process, giving rise to a σ-adduct intermediate, and subsequent formation of benzaldehyde and 3,5-dinitrobenzamide degradation products.

The hydrogenation reactivity of some classes of organic substrates (α,β-unsaturated ketones, benzaldehydes and acetophenones) was investigated using an electrocatalytic method (undivided cell, nickel sacrificial anode and water/methanol solvent). During the process a nickel deposit is produced on the cathode surface, at the same time that hydrogen is generated by water reduction. Nickel deposit morphologies (catalyst surface) were investigated, taking into account different cathode matrix materials (Cu, Ni, Fe, Fe/Ni (alloy 64:36)). The electrocatalytic method was evaluated by electrochemical efficiency of the hydrogenation process ((hydrogenation theoretical charge/experimental charge) × product yield). It was observed that Ni deposit/Ni cathode matrix ensemble exhibits slightly better catalytic activity, likely due the nanostructure of the nickel deposit. Moreover, the reactivity order determined through the electrochemical efficiencies (α,β-unsaturated ketones > benzaldehydes > acetophenones) is the same as that found in the literature.

Films of poly[( R )-(−)-3-(1-pyrrolyl)propyl- N -(3,5-dinitrobenzoyl)-α-phenylglycinate] (polyDNBP) were deposited, using the galvanostatic method, onto indium tin oxide electrodes in the presence of the electrolytes tetrabutylammonium tetrafluoro-borate [(C 4 H 9 ) 4 NBF 4 ] or LiClO 4 . Atomic force microscopy revealed that polyDNBP/(C 4 H 9 ) 4 NBF 4 films exhibited a grainy morphology with higher roughness and greater superficial area than polyDNBP/LiClO 4 films. Moreover, polyDNBP/(C 4 H 9 ) 4 NBF 4 films exhibited a higher capacitive electrochemical response when characterised in LiClO 4 rather than in (C 4 H 9 ) 4 NBF 4 . Since polyDNBP films exhibit both n- and p-doping, they may have considerable potential application as electrodes in type III capacitor assemblies.

The fluorescence quenching of TGA-CdSe quantum dots (QDs) was used for Cr(3+) quantification in vitamin supplements. The QD was electrochemically synthesized, demonstrating high reproducibility with control of particle size, thus making it a clean method, without the presence of reducing agents. Under ideal conditions, with the fluorescence band at 551 nm (excitation 365 nm), the maximum fluorescence quenching was observed at pH 4.0, with a time of 200 s for each data acquisition. Under optimum experimental conditions, linear quenching was observed for Cr(3+) in the range of 25.0-325.0 ng L(-1) (R=0.9996, n=6), a limit of detection of 5.67 ng L(-1), and relative standard deviation of 4.43% (n=10). The recovery test for Cr(3+) quantification in vitamin supplements presented results from 82% to 98%. These Cr(3+) determination results were compared to the same vitamin supplement sample using flame atomic absortion spectrometry (FAAS) method, and no significant differences were observed at 95% confidence level.

In this work, we present an alternative route to prepare silver hexacyanoferrate(II)/polyaniline (PANI) composites thin films and compare these results with the conventional chemical synthetic route, and with the electrochemical process deposited in platinum electrodes. Differently from the electrochemical method, used to synthesize the conducting polymer film on a electrode surface, this new chemical route make use of dialysis membrane as a solid support to synthesize the silver hexacyanoferrate(III) compound, and subsequently uses this composite membrane as oxidant to polymerize the aniline monomer. The spectroscopic (UV-Vis. and IR region) and electrochemical characterization (cyclic voltammetry) indicate that the polymeric composite remains optically active and conductive. The X-ray analysis show that the composite has an amorphous and a crystalline structure assigned to the conducting polymer and to the Ag4[FeII(CN)6] structure respectively.

The present contribution describes three different modern experiments for possible adoption in undergraduate organic chemistry laboratories. These are: 1. electrocatalytic hydrogenation of benzaldehyde to benzyl alcohol; 2. identification of three volatile components, obtained from pineapple fruit, by mass spectrometry and 3. microwave mediated fast synthesis of N-(p-chlorophenyl)phthalamic acid from phthalic anhydride and p-chloroaniline under solvent-free conditions. The experiments can be executed in a short period of time, putting the undergraduate student in contact with a variety of topics in organic chemistry and several techniques of analysis, showing multidisciplinarity in organic chemistry.

Although the development of conducting polymers is very recent, such materials have already been shown to possess a number of useful properties that may be exploited in a range of technological applications. In particular, the representative conducting polymer polypyrrole (PPy) has been the subject of considerable research interest owing to its facile polymerisation and practical application in products as diverse as gas sensors [1], electrochromic devices [2] and battery / capacitor components [3].

Mouse oocyte microfilaments (MF) were perturbed by depolymerization (cytochalasin B) or stabilization (jasplakinolide) and correlated meiotic defects examined by confocal microscopy. MF, microtubules, and mitochondria were vitally stained; centrosomes (γ-tubulin), after fixation. MF depolymerization by cytochalasin in culture medium did not affect central migration of centrosomes, mitochondria, or nuclear breakdown (GVBD); some MF signal was localized around the germinal vesicle (GV). In maturation-blocking medium (containing IBMX), central movement was curtailed and cortical MF aggregations made the plasma membrane wavy. Occasional long MF suggested that not all MF were depolymerized. MF stabilization by jasplakinolide led to MF aggregations throughout the cytoplasm. GVBD occurred (unless IBMX was present) but no spindle formed. Over time, most oocytes constricted creating a dumbbell shape with MF concentrated under one-half of the oocyte cortex and on either side of the constriction. In IBMX medium, the MF-containing half of the dumbbell over time sequestered the GV, MF, mitochondria, and one to two large cortical centrosomes; the non-MF half appeared empty. Cumulus processes contacted the oocyte surface (detected by microtubule content) and mirrored MF distribution. Results demonstrated that MF play an essential role in meiosis, primarily through cortically mediated events, including centrosome localization, spindle (or GV) movement to the periphery, activation of (polar body) constriction, and establishment of oocyte polarity. The presence of a cortical “organizing pole” is hypothesized.

Electrocatalytic hydrogenation (HEC) may be compared to catalytic hydrogenation (HC). The difference between these methods is the hydrogen source: HC needs a hydrogen gas supply; HEC needs a source of protons (solvent) to be reduced at a cathode surface. HEC has presented interesting advances in the last decades due to investigation of the influence of the supporting electrolyte, co-solvent, surfactant, presence of inert gas and the composition of the electrode on the reaction. Several classes of organic compounds have been hydrogenated through HEC: olefins, ketones, aldehydes, aromatics, polyaromatics and nitro-compounds. This paper shows some details about the HEC which may be regarded as a promising technique for the hydrogenation of organic compounds both in industrial processes and in laboratories.

O presente trabalho trata-se de resultados de um estudo comparativo dos Currículos prescritos de Matemática dos sistemas educativos de Brasil e México, porém, mais especificamente do Ensino Médio no Brasil e do Ensino Médio Superior no México. A análise comparativa buscou-se sinalizar as possíveis influências da Educação Matemática nos documentos oficias que regem os sistemas educacionais dos países comparados, como os Parâmetros Curriculares Nacionais de Matemática no Brasil e os Programas de Estudos das Matemáticas no México, e constata-se certas similaridades e diferenças no sistema de ensino dos países comparados. As considerações do estudo indicam que as influências da Educação Matemática nos Currículos prescritos estão presentes, como, Didática da Matemática francesa, Interdisciplinaridade, Contextualização, Resolução de Problemas, Modelagem Matemática, uso da História da Matemática e de recursos tecnológicos, e a Matemática ensinada no Brasil tende a uma formação cidadã, caso diferente no México que está focada ao conhecimento matemático.

2,2'-Bipyridine (bpy) and a series of dimethyl-2,2'-bipyridines were synthesized from 2-bromopyridine and 2-bromomethylpyridines, respectively, using an electrochemical process catalyzed by nickel complexes. The method is simple and efficient, with isolated yields between 58 and 98% according to the structure. We first studied the influence of the presence and the position of the methyl group on the yield, using N,N-dimethylformamide (DMF) or acetonitrile (AN) as the solvent, NiBr(2)bpy as the catalyst, and Zn as the sacrificial anode, in an undivided cell and at ambient temperature. On the basis of a better understanding of the reaction mechanism based on electroanalytical studies, we could improve the dimerization both by substituting the catalyst ligand (bpy) by the reagent itself, i.e., 2-bromomethylpyridine or 2-bromopyridine, and by using Fe instead of Zn as the sacrificial anode.

Three different purification methods for CdTe-MPA quantum dot (QD) were performed in aqueous medium: acid titration (HCl, HClO4, H2SO4 and CH3COOH), non-selective precipitation by addition of acetone and co-precipitation of the QD in the presence of inorganic salts. The QD stock solutions were prepared by an electrochemical method of synthesis, in four different heating times (1 h, 4 h, 8 h and 12 h). After purifications, the QD solids were redispersed in distilled water and analyzed by absorption and emission spectra. The λ abs and λ em of the purified QDs showed similar data observed for QD stock solutions, and the recovery rate varied from 71% to 99%. Co-precipitation method showed some advantages: quantum yield maintenance of the QD redispersed solution, longer period of storage (over 6 months) in solution and in solid state (QD embedded into the KCl crystal lattice). CdSe-MPA and CdS-MPA solutions were also purified by co-precipitation method with KCl, showing good results as observed for CdTe-MPA.

1-pentanol, 1-4-butanediol, 1,2-butanediol, 4-methoxybenzyl alcohol and phthalic alcohol were oxidized electrocatalytically by polypyridyl complexes of ruthenium in aqueous media. [Ru II (tpy)(bpy)(OH 2 )] 2+ , [Ru II (bpy) 2 py(OH 2 )] 2+ (py=pyridine), [Ru II (tpy)(phen)(OH 2 )] 2+ (phen=1,10-phenanthroline), cis -[Ru II (bpy) 2 (OH 2 ) 2 ] 2+ , trans -[Ru II (bpy) 2 (OH 2 ) 2 ] 2+ and trans -[Ru VI (trpy)(O) 2 (OH 2 )] 2+ were the studied complexes. A relationship between redox potential ( E 1/2 ) of the complexes and reactivity was established.