ABSTRACT The challenges for the use of the cross-laminated timber (CLT) system in the Brazilian agricultural market are significant. This study evaluated the thermal performance of fiber cement tiles associated with a CLT non-conventional structure compared to those of ceramic, fiber cement and aluminum roof tiles based on following thermal comfort indexes (i.e., black globe humidity index (BGHI), radiant heat load (RHL) and specific enthalpy) using physical conventional models of reduced-scale rural facilities under summer conditions. The non-conventional CLT model comprised closing walls and a lining that form a self-supporting structure with few air inlets. This model presented reduced thermal comfort indexes compared to the other conventional roofs. Moreover, the CLT model has an average black globe temperature (Tbg) of 32.9 °C, which was lower at all times compared to those of the other roofs. In conclusion, the roof with fiber cement tiles associated with the CLT structure exhibited the best performance in terms of thermal comfort, followed by the ceramic, fiber cement, and aluminum tiles. The study results allow a better understanding of the opportunities for CLT usage.

ABSTRACT This research was conducted with the objective of evaluating the thermal inertia and hysteresis of the following materials in a wind tunnel: hollow copper sphere with 150.0 mm diameter used as standard in globe thermometers, hollow brass sphere with 75.0 mm diameter, and two hollow plastic spheres with 115.5 and 69.7 mm diameter. The results showed that the thermal inertia and hysteresis for the hollow copper sphere were approximately 24 and 28 min, respectively; these values were bigger than those obtained for the other spheres, implying faster responses of these. While there were no statistical differences in the measurements conducted by globe thermometers which are used to indicate the black globe temperature with the different types of spheres mentioned above under indoor environment conditions, i.e., with no wind and solar radiation, the wind causes faster cooling in smaller spheres under outdoor environment conditions, which may denote erroneous interpretations of the measurements at those instants. It was concluded that it is possible to replace the hollow copper sphere of diameter 150 mm by other types of spheres to measure the black globe temperature. However, this requires knowledge of the response times of the spheres as well as corrections to be made in the measurements with respect to the globe thermometer standard.

Relevant historical aspects concerning ideal gases were briefly reviewed to provide a condensed resource for the undergraduate student of chemistry. The importance of the barometer and the concept of atmospheric pressure were reviewed and discussed. A combination of Boyle's law with the well-known equation for determining the pressure produced by a column of stationary fluid was used to obtain a graphical method for determining atmospheric pressure under isothermal conditions in the laboratory. Important aspects related to the study of ideal gases were reviewed in light of the pressure-volume data that can be obtained by physical chemistry students using a simple apparatus composed of a commercial hypodermic syringe connected to a mercury manometer. Relevant concepts associated with the measurement of a physical quantity, the importance of linear regression, as well as the use of a graphical method to test the validity of a theory were reviewed from a pedagogical perspective through the experimental study of Boyle's law during regular experimental physical chemistry classes.

O presente trabalho apresenta uma metodologia simples, rápida e de baixo custo para determinação simultânea de paracetamol (PC) e ibuprofeno (IB) em formulações farmacêuticas por voltametria de pulso diferencial usando eletrodo de diamante dopado com boro (BDD). Os analitos apresentaram picos de oxidação definidos em 0,85 V para o PC e 1,72 V para o IB (vs. Ag/AgCl) sobre o eletrodo de trabalho de BDD em meio de uma solução de H2SO4 0,1 mol L-1 com 10% (v/v) de etanol. As curvas de calibração mostraram uma resposta linear para determinação simultânea dos analitos entre 20 a 400 µmol L-1 (r² = 0,999) e os limites de detecção obtidos pelas regressões foram de 7,1 µmol L-1 e 3,8 µmol L-1 para PC e IB, respectivamente. Os estudos de adição e recuperação nas amostras ficaram próximos de 100% e os resultados foram validados por métodos cromatográficos.

This work presents a simple, fast and low-cost methodology for the simultaneous determination of paracetamol (PC) and ibuprofen (IB) in pharmaceutical formulations by differential pulse voltammetry using a boron-doped diamond (BDD) electrode. A well-defined oxidation peak was observed using the BDD electrode for each analyte (0.85 V for PC and 1.72 V for IB (vs. Ag/AgCl)) in 0.1 mol L-1 H2SO4 solution containing 10% (v/v) of ethanol. Calibration curves for the simultaneous determination of PC and IB showed a linear response for both drugs in a concentration range of 20 to 400 µmol L-1 (r² = 0.999), with a detection limit of 7.1 µmol L-1 for PC and 3.8 µmol L-1 for IB. The addition-recovery studies in samples were about 100% and the results were validated by chromatographic methods.

Surface and electrochemical properties of the dimensionally stable anode Ti/(Ru0.3Ti0.7)O2 were studied as a function of the annealing temperature using different conditions in order to perform the cooling process of the oxide films (conventional thermal shock and the slow cooling processes). It was found that surface and electrochemical properties for the oxygen evolution reaction are both affected through the cooling process, being the electrode prepared at 400 ºC using the slow cooling process the less susceptible to wear. The Tafel slope obtained in the high overpotential domain was analysed in light of the apparent charge transfer coefficient.

OBJETIVO: Avaliar o efeito citotóxico de dois antidepressivos comumente utilizados na prática, a paroxetina e a bupropriona. Além disso, buscou-se avaliar a atividade natural killer (ANK) após a incubação dos linfócitos com esses fármacos. MÉTODOS: Sangue venoso de 15 participantes foi coletado e as células mononucleares (PBMCs) foram separadas e incubadas por 24h com (ou sem = grupo-controle) concentrações de paroxetina e bupropiona em 30, 100 e 1.000 ng/ml. Após a incubação, a quantidade das células mortas foi contada utilizando-se o método trypan blue. Posteriormente foi avaliada a ANK por meio do ensaio clássico de liberação do Cr51. CONCLUSÕES: Ocorreu morte celular de PBMCs proporcionais às doses dos fármacos, no entanto, a ANK não foi afetada, mesmo com a redução do número de células efetoras.

OBJECTIVE: This study aims to evaluate the citotoxic activity of two commonly used anti-depressants: paroxetine and bupropion. We also evaluated the in vitro natural killer activity (NKA) after incubating the blood samples with the antidepressants. METHODS: Peripheral blood samples from 15 healthy volunteers were collected and the mononuclear cells (PBMCs) were isolated and incubated for 24h with (or without = control cells) paroxetine and bupropion, in concentrations of 30, 100 and 1000 ng/ml. After the incubation period in both groups, the amount of dead cells was calculated using trypam blue technique. NKA was evaluated using the classic51Cr release assay. CONCLUSIONS: PBMCs dead cells occurred in both groups and in proportion to all pharmacological concentrations. Nevertheless, the NKA was not affected, even with the reduction in the number of effective cells.

A influência da composição do eletrólito (ácido sulfúrico, ácido perclórico e suas misturas) sobre a cinética eletródica da reação de desprendimento de oxigênio (RDO) e a produção eletroquímica de ozônio (PEO) em eletrodo de beta-PbO2, foi investigada empregando-se a espectroscopia de impedância eletroquímica e curvas de polarização quase-estacionárias. A análise dos espectros de impedância revelou uma dependência da capacitância da dupla camada elétrica e da pseudo-capacitância de adsorsão dos intermediários da reação com a composição do eletrólito. A pseudo-capacitância é função do potencial do eletrodo e da composição do eletrólito, indicando que a cobertura superficial pelos intermediários da reação depende destes parâmetros. Os valores do coeficiente de Tafel apoiam a descarga primária da água como sendo a etapa determinante da velocidade do mecanismo eletródico descrevendo a RDO e a PEO. Os valores da eficiência da corrente para a PEO (fiPEO) mostram que os eletrólitos puros resultam numa produção máxima de ozônio quando comparados aos eletrólitos mistos. Baseada na análise teórica do mecanismo eletródico, este comportamento é conseqüente da redução na concentração superficial dos centros ativos responsáveis pela PEO ocasionada pela adsorsão de ânions.

The influence of electrolyte composition (pure sulphuric or perchloric acid and their mixtures) on the kinetics of the oxygen evolution reaction (OER) and the electrochemical ozone production (EOP) on beta-PbO2 electrodes was investigated by electrochemical impedance spectroscopy and quasi-stationary polarisation curves. Analysis of the impedance spectra revealed a dependency of the electric double layer capacity and the adsorption pseudocapacitance, due to reaction intermediates, on electrolyte composition. The pseudocapacitance is a function of electrode potential and electrolyte composition, indicating the surface coverage by the reaction intermediates depends on these parameters. Tafel slope data support primary water discharge as rate determining step of the OER and EOP electrode processes. EOP current efficiency data (phiEOP) show pure electrolytes lead to maximum O3 production when compared to mixed electrolytes. According to the theoretical analysis of the electrode mechanism, this behaviour is a consequence of the reduction in surface concentration of the active centres leading to EOP caused by anion adsorption.

Efforts presented by the scientific community in recent years towards the development of numerous green chemical processes and wastewater treatment technologies are presented and discussed. In the light of these approaches, environmentally friendly technologies, as well as the key role played by the well-known advanced oxidation processes, are discussed, giving special attention to the ones comprising ozone applications. Fundamentals and applied aspects dealing with ozone technology and its application are also presented.

After an introductory discussion emphasising the importance of electrochemistry for the so-called Green Chemical Processes, the article presents a short discussion of the classical ozone generation technologies. Next a revision of the electrochemical ozone production technology focusing on such aspects as: fundamentals, latest advances, advantages and limitations of this technology is presented. Recent results about fundamentals of electrochemical ozone production obtained in our laboratory, using different electrode materials (e.g. boron doped diamond electrodes, lead dioxide and DSAÒ-based electrodes) also are presented. Different chemical processes of interest to the solution of environmental problems involving ozone are discussed.

A investigação do mecanismo eletródico e das propriedades eletrocatalíticas da reação de desprendimento de cloro, RDCl, foi executada em eletrodos mistos de óxido do tipo rutila e espinélio de composição nominal Ti/[RuO2(x)+Co3O4(1-x)]. Os eletrodos foram preparados por decomposição térmica (Tcalc. = 470ºC; t calc. = 1h), com x variando entre 0 e 1 mudado em intervalos de 0,1. O estudo cinético foi executado registrando-se curvas corrente-potencial e pela determinação da ordem de reação com respeito aos íons H+ e Cl-. Um valor constante do coeficiente de Tafel de 33 mV foi obtido para concentrações de RuO2 entre 0-80% mol, aumentando para 40 mV para concentrações superiores de RuO2. Os dados experimentais apoiam o mecanismo de Erenburg e cols. para a RDCl. Um único mecanismo explica os resultados experimentais assumindo que o efeito "edge" influencie os valores do coeficiente de transferência eletrônica. A análise da atividade eletrocatalítica mostra que misturas de óxidos aumentam a atividade eletrocatalítica aparente.

A systematic investigation of the mechanistic and electrocatalytic properties of the chlorine evolution reaction, ClER, on mixed rutile/spinel oxides of nominal composition Ti/[RuO2(x)+Co3O4(1-x)] was done. Electrodes were prepared using the thermal decomposition procedure (Tcalc. = 470ºC; t calc. = 1h), with x varied between 0 and 1, changed in 0.1 steps. Kinetics were studied recording quasi-stationary current-potential curves and reaction order determined with respect to H+ and Cl-. A constant Tafel slope of about 33 mV was found for the 0 - 80 mol% RuO2 concentration interval, increasing to 40 mV for higher RuO2 contents. Experimental data support the mechanism originally proposed by Erenburg et al. for the ClER. The edge effect exerts an influence on the electronic transfer coefficient values. Analysis of the electrocatalytic activity reveals an increase in the apparent electrocatalytic activity for the mixed oxides.