Studies on the kinetics of ascorbate oxidation at a ruthenium oxide hexacyanoferrate modified electrode towards the detection at microenvironments

The electrocatalytic oxidation of ascorbate on a ruthenium oxide hexacyanoferrate (RuOHCF) glassy carbon (GC) modified electrode was investigated at pH 6.9 by using rotating disc electrode (RDE) voltammetry. The influence of the systematic variation of rotation rate, film thickness, ascorbate concentration and the electrode potential indicated that the rate of cross-chemical reaction between Ru(III) centres immobilized into the film and ascorbate controls the overall process. The kinetic regime may be classified as a Sk `` mechanism and the second order rate constant for the surface electrocatalytic reaction was found to be 1.56 x 10(-3) mol(-1) L-1 s(-1) cm. A carbon fibre microelectrode modified with the RuOHCF film was successfully used as an amperometric sensor to monitor the ascorbate diffusion in a simulated microenvironment experiment. (C) 2008 Elsevier B.V. All rights reserved.

Thermo-solvatochromism of merocyanine polarity probes - What are the consequences of increasing probe lipophilicity through annelation?

The question raised in the title has been answered by comparing the solvatochromism of two series of polarity probes, the lipophilicities of which were increased either by increasing the length of an alkyl group (R) attached to a fixed pyridine-based structure or through annelation (i.e., by fusing benzene rings onto a central pyridine-based structure). The following novel solvatochromic probes were synthesized: 2,6-dibromo-4-[(E)-2-(1-methylquinolinium-4-yl)ethenyl]-phenolate (MeQMBr(2)) and 2,6-dibromo-4-[(E)-2-(1-methyl-acridinium-4- yl) ethenyl)]phenolate (MeAMBr(2) The solvatochromic behavior of these probes, along with that of 2,6dibromo-4-[(E)-2-(1-methylpyridinium-4-yl)ethenyl]phenol-ate(MePMBr(2)) was analyzed in terms of increasing probe lipophilicity, through annelation. Values of the empirical solvent polarity scale [E(T)(MePMBr(2))] in kcalmol(-1) correlated linearly with ET(30), the corresponding values for the extensively employed probe 2,6-diphenyl-4-(2,4,6-triphenylpyridinium-1-yl)phenolate (RB). On the other hand, the nonlinear correlations of ET(MeQMBr(2)) or ET(MeAMBr(2)) with E(T)(30) are described by second-order polynomials. Possible reasons for this behavior include: i) self-aggregation of the probe, ii) photoinduced cis/trans isomerization of the dye, and iii) probe structure- and solvent-dependent contributions of the quinonoid and zwitterionic limiting formulas to the ground and excited states of the probe. We show that mechanisms (i) and (ii) are not operative under the experimental conditions employed; experimental evidence (NMR) and theoretical calculations are presented to support the conjecture that the length of the central ethenylic bond in the dye increases in the order MeAMBr(2) > MeQMBr(2) > MePMBr(2), That is, the contribution of the zwitterionic limiting formula predominates for the latter probe, as is also the case for RB, this being the reason for the observed linear correlation between the ET(MePMBr2) and the ET(30) scales. The effect of increasing probe lipophilicity on solvatochromic behavior therefore depends on the strategy employed. Increasing the length of R affects solvatochromism much less than annelation, because the former structural change hardly perturbs the energy of the intramolecular charge-transfer transition responsible for solvatochromism. The thermo-solvatochromic behavior (effect of temperature on solvatochromism) of the three probes was studied in mixtures of water with propanol and/or with DMSO. The solvation model used explicitly considers the presence of three ""species"" in the system: bulk solution and probe solvation shell [namely, water (W), organic solvent (Solv)], and solvent-water hydrogen-bonded aggregate (Solv-W). For aqueous propanol, the probe is efficiently solvated by Solv-W; the strong interaction of DMSO with W drastically decreases the efficiency of Solv-W in solvating the probe, relative to its precursor solvents. Temperature increases resulted in desolvation of the probes, due to the concomitant reduction in the structured characters of the components of the binary mixtures.

Alkaloids from the Bark of Guatteria hispida and Their Evaluation as Antioxidant and Antimicrobial Agents

Phytochemical investigation of the bark of Guatteria hispida afforded three new alkaloids, 9-methoxy-O-methylmoschatoline (1), 9-methoxyisomoschatoline (2), and isocerasonine (3), along with 10 known alkaloids, 8-oxopseudopalmatine (4), O-methylmoschatoline (5), lysicamine (6), liriodenine (7), 10-methoxyliriodenine (8), nornuciferine (9), anonaine (10), xylopine (11), coreximine (12), and isocoreximine (13). The major compounds, 2, 6, 12, and 13, showed significant antioxidant capacity in the ORAC(FL), assay. Compounds 5, 6, and 7 were active against S. epidermidis and C. dubliniensis, with MIC values in the range 12.5-100 mu g mL(-1).

In Situ Infrared (FTIR) Study of the Mechanism of the Borohydride Oxidation Reaction on Smooth Pt Electrode

Although Pt has been thoroughly studied regarding its activity for the borohydride oxidation reaction (BOR), the BOR mechanism at Pt remains unclear: Depending on the applied potential, spontaneous BH(4)(-) hydrolysis can compete with the direct BOR. The goal of the present work is to provide more insight into the behavior of smooth Pt electrodes toward the BOR, by coupling in situ infrared reflectance spectroscopy with electrochemistry. The measurements were performed on a Pt electrode in 1 M NaOH/1 M NaBH(4), so as to detect the reaction intermediate species generated as a function of the applied potential. Several bands were monitored in the B-H ((v) over bar approximate to 1180, 1080, and 972 cm(-1)) and B-O ((v) over bar = 1325 and similar to 1425 cm(-1)) bond regions upon increased electrode polarization. These absorption bands, which appear sequentially and were already detected for similar measurements on Au electrodes, are assigned to BH(3), BH(2), and BO(2)(-) species. In light of these experimental data and previous results obtained in our group for Pt- or Au-based electrodes, possible initial elementary steps of the BOR on platinum electrodes are proposed and discussed according to the relevant literature data.

Growth of transcendental meditation: a sociological study

Sociology, in concerning itself with methodology and cultural determinism,may have overlooked the value of human experience in determining social action. We feel that the structural-functionalist point of view is not mutually exclusive with that of symbolic interaction theory. The field of collective behavior has not adequately explained a certain incidence of human activity called Transcendental Meditation. This paper will define Transcendental Meditation in sociological terms and explore its growth in terms of structural-functionalism,as well as in terms of the symbol-making faculty of human experience. In the first chapter, the author will state his biases and background as well as the problem and purpose of the paper. In the second chapter, Transcendental Meditation will be defined through an explanation of its concepts in sociological terms. A view of the TM program will also be reported. Following this in the third chapter, the origins of TM will be discussed~showing its basis to be in a tradition of Indian gurus and following its development in the United states until the present. The history of TM will proceed through biography of leading figures, with special mention of innovations in the TM institution of teaching and events in the growth of the 'movement' of TOO that are of key importance. Having set down the history of TM, in the fourth chapter we will discuss TM in terms of various sociological models. We will try to identify TM as either a social movement; a charismatic organization or a bureaucracy. In the fifth chapter we will look more closely at the structure of the organization that teaches TM in regard to its own functioning; that is, compliance, communication, socialization and recruitment, and also in regard to its relationship with national institutions, such as military, industry, religion, and government. Finally, we will explore TM in terms of individual and group goals and offer an explanation defining the growth of TM. Throughout-the paper, sociological perspectives will be applied to phenomena that exist in the society today. It is not within the scope of this paper to verify all the sociological implications and appraisals offered. It is hoped that this will not invalidate the ensuing discussion. It is also hoped that this paper will expand the horizons of sociology and offer some direction in future studies of collective behavior. If this is accomplished, the author will be gratified and indebted to his teachers. If not the author takes full responsibility. This paper is dedicated therefore to Mr. Birge, Mr Morrione, Mr. Geib as well as to my parents who have encouraged me, my friends whom I have interviewed, and to His Holiness, Maharishi Mahesh Yogi whose teaching has uplifted hundred of thousands of people in the world and may bring about the development of new thresholds of peace and prosperity for mankind.

Chuveiro lava-olhos

Este modelo é parte de um conjunto de modelos 3D produzidos pela equipe de audiovisual da SEaD/UFSCar para o jogo de realidade virtual “O Laboratório de Química”.

Elite municipal da Ponta do Sol: 1878-1886

A presente investigação desenvolve um estudo sobre o percurso histórico das elites municipais do concelho da Ponta do Sol, entre 1878 e 1886, inserindo-as no contexto global das regras definidas pelo suporte legislativo do Código Administrativo de 1878, bem como no espaço socioeconómico, onde detiveram um papel preponderante e decisivo nos destinos do mesmo. Esta dissertação analisa a realidade local na construção de uma identidade municipal, aplicando métodos e técnicas de investigação histórica. A partir de fontes manuscritas, como os recenseamentos eleitorais, este trabalho faz a inventariação do corpus eleitoral do concelho supramencionado, isto é, a caracterização socioeconómica dos cidadãos habilitados a votar (eleitores) e dos elegíveis, culminando nos eleitos para os cargos municipais. De igual modo, procurou conhecer as áreas de intervenção da Câmara Municipal da Ponta do Sol e respetivos espaços de atuação da elite dirigente camarária.

Antimicrobial resistance of heterotrophic marine bacteria isolated from seawater and sands of recreational beaches with different organic pollution levels in southeastern Brazil: evidences of resistance dissemination

Antimicrobial resistance of marine heterotrophic bacteria to different antimicrobials agents were evaluated in seawater, dry and wet sands from three marine recreational beaches with different pollution levels. In all studied beaches, the greatest frequencies of resistance were found in relation to penicillin. on Gonzaguinha, the most polluted beach, 72.3% of all isolated strains showed simple resistance, whilst 8.33% had multiple resistance. The values found on Ilha Porchat beach, were 70.8% and 6.9% for simple and multiple resistances, respectively. on GuaraA(0), the less polluted beach, only 35.3% of isolated strains had simple resistance. Multiple resistance was not observed. While samples from Gonzaguinha and Ilha Porchat beach showed isolated strains resistant to seven and six different antimicrobial agents, respectively, samples from GuaraA(0) beach were resistant only to penicillin and erytromicin. The positive correlations obtained between the degree of seawater contamination and frequency and variability of bacterial resistance indicate that polluted marine recreational waters and sands are sources of resistant bacteria contributing thus, to the dissemination of bacterial resistance.

MICROPROPAGAÇÃO do KIWI CV. HAYWARD

O presente trabalho teve como objetivo desenvolver um protocolo para a obtenção de mudas de kiwi (Actinidia chinensis Planch), cv. Hayward, por meio do cultivo in vitro de cotilédones. Utilizou-se o meio de MURASHIGE & SKOOG (1962) -- MS, suplementado com dois tipos de auxina (AIA e AIB) e uma citocinina (BAP). Foram verificados os efeitos de três doses de auxinas (0,125; 0,250 e 0,375 mg.L-1), combinadas com três doses de citocinina (0,5; 1,0 e 1,5 mg.L-1) na capacidade morfogênica dos explantes. Procedeu-se o estudo histológico dos órgãos das plântulas obtidas in vitro, e verificou-se, também, a capacidade de aclimatação das mudas ex vitro. A menor dose de AIB (0,125 mg.L-1), independentemente das doses de BAP, foi a mais eficaz na morfogênese dos explantes. Não foram verificadas alterações histológicas e anatômicas das plântulas obtidas in vitro. Aos três meses após o cultivo ex vitro dos explantes, verificou-se a sobrevivência de 88% das plantas transplantadas em condições de campo.

Modeling of optoelectronic devices through neuro-fuzzy architectures

The advantages offered by the electronic component LED (Light Emitting Diode) have caused a quick and wide application of this device in replacement of incandescent lights. However, in its combined application, the relationship between the design variables and the desired effect or result is very complex and it becomes difficult to model by conventional techniques. This work consists of the development of a technique, through comparative analysis of neuro-fuzzy architectures, to make possible to obtain the luminous intensity values of brake lights using LEDs from design data.

In situ application of a cellulose bag and an ion exchanger for differentiation of labile and inert metal species in aquatic systems

This work involved the development and application of a new analytical procedure for in-situ characterization of the lability of metal species in aquatic systems by using a system equipped with a diffusion membrane and cellulose organomodified with p-aminobenzoic acid groups (DM-Cell-PAB). To this end, the DM-Cell-PAB system was prepared by adding cellulose organomodified with p-aminobenzoic acid groups (Cell-PAB) to pre-purified cellulose bags. After the DM-Cell-PAB system was sealed, it was examined in the laboratory. The in-situ application involved immersing the DM-Cell-PAB system in two different rivers, enabling us to study the relative lability of metal species (Cu, Cd, Fe, Mn, and Ni) as a function of time and quantity of exchanger. The procedure is simple and opens up a new perspective for understanding environmental phenomena relating to the complexation, transport, stability, and lability of metal species in aquatic systems rich in organic matter.

Gestão dos resíduos sólidos no Brasil e seus rebatimentos em Natal, Brasil

O artigo apresenta a gestão dos resíduos sólidos no Brasil e seus rebatimentos na cidade de Natal/RN, verificando seus aspectos ambientais, econômicos e sociais. O fracasso da coleta seletiva revelado nos baixos índices de recuperação dos materiais; a baixa relevância da inclusão socioeconômica dos catadores que participam do programa assistencialista oficial; a inexistência de estratégias oficiais para que se minimize a quantidade de resíduos que se gera cada dia e o aumento exagerado dos gastos públicos, sobretudo com o tratamento dos resíduos no aterro sanitário, demonstram que a gestão de resíduos em Natal, conforme parâmentros da Política Nacional de Residuos Sólidos, objetiva o controle destes na cidade e a consolida- ção do tratamento finalista através do envio da quase totalidade dos resíduos coletados ao aterro sanitário