Physical-chemical and thermodynamic analyses of ethanol steam reforming for hydrogen production

Steam reforming is the most usual method of hydrogen production due to its high production efficiency and technological maturity the use of ethanol for this purpose is an interesting option because it is a renewable and environmentally friendly fuel. The objective of this article is to present the physical-chemical, thermodynamic, and exergetic analysis of a steam reformer of ethanol, in order to produce 0.7 Nm(3)/h of hydrogen as feedstock of a 1 kW PEMFC the global reaction of ethanol is considered. Superheated ethanol reacts with steam at high temperatures producing hydrogen and carbon dioxide, depending strongly on the thermodynamic conditions of reforming, as well as on the technical features of the reformer system and catalysts. The thermodynamic analysis shows the feasibility of this reaction in temperatures about 206 degrees C. Below this temperature, the reaction trends to the reactants. The advance degree increases with temperature and decreases with pressure. Optimal temperatures range between 600 and 700 degrees C. However, when the temperature attains 700 degrees C, the reaction stability occurs, that is, the hydrogen production attains the limit. For temperatures above 700 degrees C, the heat use is very high, involving high costs of production due to the higher volume of fuel or electricity used. The optimal pressure is 1 atm., e.g., at atmospheric pressure. The exergetic analysis shows that the lower irreversibility is attained for lower pressures. However the temperature changes do not affect significantly the irreversibilities. This analysis shows that the best thermodynamic conditions for steam reforming of ethanol are the same conditions suggested in the physical-chemical analysis.

Influence of organic-mineral fertilization of an oxisol on soil chemical properties and Bracharia brizantha production

A utilização de fertilizante organomineral da indústria produtora dos aminoácidos lisina e treonina pode melhorar a fertilidade de solos tropicais. O presente trabalho teve como objetivo avaliar a influência de diferentes dosagens do fertilizante organomineral denominado Ajifer L-14 nos atributos químicos e no aumento de produção de forragem de um Latossolo Vermelho do noroeste paulista. O delineamento utilizado foi em blocos casualizados, com sete tratamentos e quatro repetições. Os tratamentos foram: T1- testemunha (sem aplicação de Ajifer L-14); T2- testemunha com vegetação natural; T3- adubação mineral de acordo com a necessidade da cultura e a análise do solo (usando 1,35 kg de ureia, 2,20 kg de superfosfato simples e 0,51 kg de KCl por parcela, o que corresponde a 60 kg de N, 40 kg de P2O5 e 30 kg ha-1 de K2O, respectivamente); T4- adubação com Ajifer L-14 de acordo com a recomendação da análise química do solo (40 L parcela-1, o que corresponde a 60 kg ha-1 N); T5- adubação com Ajifer L-14 em dosagem 50 % acima da recomendação (60 L parcela-1, o que corresponde a 90 kg ha-1 N; T6- adubação com Ajifer L-14 em dosagem 50 % abaixo da recomendação (20 L parcela-1, o que corresponde a 30 kg ha-1 N); T7- adubação com Ajifer L-14 em dosagem 25 % acima da recomendação (50 L parcela-1, o que corresponde a 75 kg ha-1 N); e T8- adubação com Ajifer L-14 em dosagem 25 % abaixo da recomendação (30 L parcela-1, o que corresponde a 45 kg ha-1 N). Nas profundidades de 0,0-0,1 e 0,1-0,2 m, avaliaram-se os seguintes atributos químicos do solo:, teor de matéria orgânica (MO), pH, K+, Ca2+, Mg2+, capacidade de troca catiônica (CTC), acidez potencial e saturação por bases. A aplicação do fertilizante organomineral não influenciou os atributos químicos do solo. Na análise de regressão, houve relação polinomial entre as doses de aplicação do fertilizante organomineral e a produção de massa seca e proteína bruta de Bracharia brizantha.

Mechanical, physical, and chemical characterization of Ti-35Nb-5Zr and Ti-35Nb-10Zr casting alloys

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

Chemical detection of the proteins and lipids in the fat body cells from workers of Attini ants (Hymenoptera: Formicidae)

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

Anatomical characterization and chemical profile of Laguncularia racemosa (L.) Gaertn leaf blades, from impacted and non-impacted mangroves of the São Paulo Coast

Anatomical characterization and chemical profile of Laguncularia racemosa (L.) Gaertn leaf blades, from impacted and non-impacted mangroves of the São Paulo Coast. Several sources of environmental impact have caused great damage to the flora in mangroves. Therefore, this study aimed to analyze the anatomy and chemical composition of Laguncularia racemosa (L.) Gaertn leaf blades, from impacted (Municipality of Santos) and non-impacted mangroves (Municipality of Peruibe) of the São Paulo Coast. For the leaf anatomy studies, light microscopy and scanning electron microscopy (SEM) were used. For chemical analysis, high performance liquid chromatography (HPLC) was conducted. The biometry revealed leaf tissues of plants from impacted mangroves with a less thick epidermis and mesophyll and higher width of the central vascular beam. A smaller number of stomata and higher amounts of daises in these leaves were also observed. Results were confirmed by the Student t-test (alpha = 5%). The chemical profiles revealed a higher ammount of secondary metabolites in leaves from the impacted environment.

Associação de cetamina S(+) e midazolam pelo método convencional de cálculo e pela extrapolação alométrica em bugios-ruivo (Alouatta guariba clamitans): resposta clínica e cardiorrespiratória

O objetivo deste estudo foi avaliar o protocolo de contenção química com cetamina S(+) e midazolam em bugios-ruivos, comparando o cálculo de doses pelo método convencional e o método de extrapolação alométrica. Foram utilizados 12 macacos bugios (Alouatta guariba clamitans) hígidos, com peso médio de 4,84±0,97kg, de ambos os sexos. Após jejum alimentar de 12 horas e hídrico de seis horas, realizou-se contenção física manual e aferiram-se os seguintes parâmetros: frequência cardíaca (FC), frequência respiratória (f), tempo de preenchimento capilar (TPC), temperatura retal (TR), pressão arterial sistólica não invasiva (PANI) e valores de hemogasometria arterial. Posteriormente, os animais foram alocados em dois grupos: GC (Grupo Convencional, n=06), os quais receberam cetamina S(+) (5mg kg-1) e midazolam (0,5mg kg-1), pela via intramuscular, com doses calculadas pelo método convencional; e GA (Grupo Alometria, n=06), os quais receberam o mesmo protocolo, pela mesma via, utilizando-se as doses calculadas pelo método de extrapolação alométrica. Os parâmetros descritos foram mensurados novamente nos seguintes momentos: M5, M10, M20 e M30 (cinco, 10, 20 e 30 minutos após a administração dos fármacos, respectivamente). Também foram avaliados: qualidade de miorrelaxamento, reflexo podal e caudal, pinçamento interdigital, tempo para indução de decúbito, tempo hábil de sedação, qualidade de sedação, e tempo e qualidade de recuperação. O GA apresentou menor tempo para indução ao decúbito, maior grau e tempo de sedação, bem como redução significativa da FC e PANI de M5 até M30, quando comparado ao GC. Conclui-se que o grupo no qual o cálculo de dose foi realizado por meio da alometria (GA) apresentou melhor grau de relaxamento muscular e sedação, sem produzir depressão cardiorrespiratória significativa.

Oxisol subsurface chemical attributes related to sugarcane productivity

Embora haja homogeneidade nas características morfológicas na classe dos Latossolos, existe grande diversidade química na subsuperfície. Trabalhos indicam que a produção agrícola apresenta correlação significativa com atributos químicos de subsuperfície, que são mais estáveis que na camada arável, sujeita a alterações decorrentes da exploração agrícola. Pelo exposto, o presente estudo avaliou os efeitos dos atributos químicos de subsuperfície de Latossolos da região Centro-Sul do Brasil na produtividade agrícola dos três primeiros cortes de clones de cana-de-açúcar e da variedade RB72454. Utilizaram-se os dados de produtividade agrícola correspondentes ao período de 1993 a 1998. Os solos foram caracterizados sob o ponto de vista granulométrico e químico na profundidade entre 0,8 e 1,0 m e foram feitos estudos de correlação entre tais atributos e as médias de produtividade agrícola diária durante o ciclo dos clones de cada ensaio e da variedade RB72454 e análise de regressão múltipla, com as variáveis selecionadas pelo procedimento stepwise em função do R². As características químicas de subsuperfície dos Latossolos influenciaram na produtividade agrícola da cana-de-açúcar, principalmente no 3º corte. Para as médias dos clones, o modelo de produtividade do 3º corte em função de saturação por bases e fósforo, mostra R² = 0,31, ou seja, que 31% da variação de TCH dia-1 pode ser explicada por esses dois atributos. No caso da variedade RB72454, essa mesma variação no 3º corte é explicada em 47% pelos atributos soma de bases e teores de cálcio e matéria orgânica. As variações de produtividade de 1º e 2º cortes foram melhor explicadas pelo pHágua.

Characterization, feasibility and optimization of Agaricus subrufescens growth based on chemical elements on casing layer

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Application of on-line C30 RP-HPLC-NMR for the analysis of flavonoids from leaf extract of Maytenus aquifolium

The application of on-line C30-reversed-phase high-pressure liquid chromatography-nuclear magnetic resonance spectroscopy is described for the analysis of tetraglycosylated flavonoids in aqueous and hydroalcoholic extracts of the leaves of Maytenus aquifolium (Celastraceae). Triacontyl stationary phases showed adequate separation for on-line 1H-NMR measurements at 600 MHz and allowed the characterisation of these flavonoids by detection of both aromatic and anomeric proton signals. Copyright (C) 2000 John Wiley and Sons, Ltd.

Características hematológicas, bioquímicas e biométricas de Piaractus mesopotamicus Holmberg, 1887 (Osteichthyes: Characidae) oriundos de cultivo intensivo

Hematological characteristics are important tools for diagnosis and prognostic features in fish population and they contribute to the comprehension of comparative physiology, phylogenetic relation, food habit and other ecological parameters. Red blood cell count (RBC), white blood cell count (WBC), thrombocytes counts, glucose, cortisol, hepatosomatic and splenosomatic relation were evaluated in Piaractus mesopotamicus. The values of hepatosomatic relation varied from 0.67% to 2.79% and splenosomatic relation from 0.011% to 0.108%. RBC 1.870 to 4.590 × 106/μL, hemoglobin concentration 5.7 to 12.1g/dL, haematocrit 24.0% to 40.0%, mean corpuscular volume 98.0 to 174.0 fL, mean corpuscular haemoglobin concentration 19.1 to 34.2g/dL, glucose 40.6 to 89.2mg/dL and cortisol 4.73 to 110.5ng/dL The number of total thrombocytes was 12,160.0 to 89,280.0/μL and WBC 2,019.0 to 47,473.0/μL. Differential count of leucocytes showed 54.1% limphocytes, 10.9% neutrophils, 10.3% monocytes, 9.9% PAS-positive granular leukocytes (PAS-GL), 6.7% eosinophils, 0.3% basophils and 7.8% immature leucocytes. Variation of these haematological characteristics in the same fish species was observed, being considered as the normal variation in the fish concerned. Hence it is incorrect to assume that biological characteristics in fishes are distributed normally.

Evaluation of the combined solar TiO2/photo-Fenton process using multivariate analysis

The effect of combining the photocatalytic processes using TiO 2 and the photo-Fenton reaction with Fe3+ or ferrioxalate as a source of Fe2+ was investigated in the degradation of 4-chlorophenol (4CP) and dichloroacetic acid (DCA) using solar irradiation. Multivariate analysis was used to evaluate the role of three variables: iron, H2O2 and TiO2 concentrations. The results show that TiO2 plays a minor role when compared to iron and H2O2 in the solar degradation of 4CP and DCA in the studied conditions. However, its presence can improve TOC removal when H2O2 is totally consumed. Iron and peroxide play major roles, especially when Fe(NO3)3 used in the degradation of 4CP. No significant synergistic effect was observed by the addition of TiO 2 in this process. On the other hand, synergistic effects were observed between FeOx and TiO2 and between H 2O2 and TiO2 in the degradation of DCA. © IWA Publishing 2004.

The β-chemokines MIP-1α and RANTES and lipoprotein metabolism in HIV-infected Brazilian patients

HIV patients are predisposed to the development of hypertriglyceridemia and hypercholesterolemia as a result of both viral infection and HIV infection therapy, especially the protease inhibitors. Chemokines and cytokines are present at sites of inflammation and can influence the nature of the inflammatory response in atherosclerosis. We investigated the correlation between biochemical variables and β-chemokines (MIP-1α and RANTES) and the apolipoprotein E genotype in HIV-infected individuals. The apolipoproteins were measured by nephelometry. Triglycerides and total cholesterol were determined by standard enzymatic procedures. The β-chemokines were detected by ELISA. The genetic category of CCR5 and apolipoprotein E were determined by PCR amplification and restriction enzymes. Immunological and virological profiles were assessed by TCD4 + and TCD8 + lymphocyte counts and viral load quantification. Positive correlations were found between apo E and CD8 + (p = 0.035), apo E and viral load (p = 0.018), MIP-1α and triglycerides (p = 0.039) and MIP-1α and VLDL (p = 0.040). Negative correlations were found between viral load and CD4 + (p = 0.05) and RANTES and CD4 + (p = 0.029). The β-chemokine levels may influence lipid metabolism in HIV-infected individuals. © 2005 by The Brazilian Journal of Infectious Diseases and Contexto Publishing. All rights reserved.

Physical-chemical and thermodynamic analyses of steam reforming of ethanol to hydrogen production

The steam reforming is one of most utilized process of hydrogen production because of its high production efficiencies and its technological maturity. The use of ethanol for this purpose is a interesting option because this is a renewable and less environmentally offensive fuel. The objective of this study is evaluate the physical-chemical, thermodynamic and environmental analyses of steam reforming of ethanol. whose objective is to produce 0.7 Nm3/h of hydrogen to be used by a PEMFC of l kW. In this physical-chemical analysis, a global reaction of ethanol was considered. That is, the superheated ethanol and steam, at high temperatures, react to produce hydrogen and carbon dioxide. Beyond it's the simplest form to study the steam reforming of ethanol to hydrogen production, it's the case where occurs the highest production of hydrogen (the product to be used by fuel cells) and carbon dioxide, to be eliminated. But this reaction isn't real and depends greatly on the thermodynamic conditions of reforming, technical features of reformer system and catalysts. Other products generally formed (but not investigated in this study) are methane, carbon monoxide, among others. It was observed that the products is commonly produced in the moment when the reaction attains temperatures about 206°C (below this temperature, the reaction trend to the reaetants, that is, from hydrogen and carbon dioxide to steam and ethanol) and the advance degree of this reaction increases when the temperature of reaction also increases and when its pressure decreases. It's suggested reactions at about 600°C or higher. However, when the temperature attains 700°C, the stability of this reaction is occurred, that is, the production of reaction productions attains to the limit, that is the highest possible production. In temperatures above 700°C, the use of energy is very high for produce more products, having higher costs of production that the suggested temperature. The indicated pressure is 1 atm., a value that allows a desirable economy of energy that would also be used for pressurization or depressurization of steam reformer. In exergetic analysis, it's seem that the lower irreversibililies occur when the pressure of reactions are lower. However, the temperature changes don't affect significantly the irreversibilites. Utilizing the obtained results from this analysis, it was concluded that the best thermodynamic conditions for steam reforming of ethanol is the same conditions suggested in the physical-chemical analysis. The exergetic and first law efficiencies are high on the thermodynamie conditions studied.

Methanol oxidation on PtRu/C electrocatalysts prepared by a microemulsion method

PtRu/C nanocatalysts were prepared by a microemulsion method using different values of water/surfactant molar ratio in order to get different particle sizes. Crystallite sizes and structural properties were determined by X-ray diffraction. Particle size and distribution were characterized by transmission electron microscopy and average composition was determined by energy dispersive X-ray analysis. Differential scanning calorimetry measurements indicated the presence of oxides in the as-prepared catalysts. The general electrochemical behavior was evaluated by cyclic voltammetry in 0.5 M sulfuric acid and the electrocatalytic activity towards the oxidation of methanol was studied in 0.5 M methanol acid solutions by potential sweeps and chronoamperometry. copyright The Electrochemical Society.

Oxygen reduction on PtFe/C electrocatalysts prepared in microemulsions

PtFe/C nanocatalysts of different compositions and nearly constant particle size were prepared by a microemulsion method. Crystallite sizes and degree of alloying were determined by X-ray diffraction. Particle size and distribution were characterized by transmission electron microscopy and average composition was determined by energy dispersive X-ray analysis. Measurements of electrocatalytic activity for oxygen reduction were done using the rotating disk electrode technique in O2 saturated 0.5 mol L-1 sulfuric acid solutions, at room temperature. For all catalysts oxygen reduction begins at ̃ 0.90V. Tafel plots show slopes of c.a. 60 and 120 mV dec in the regions of low and high overpotentials, respectively. The best results for the ORR were obtained for the PtFe/C catalyst of composition Pt:Fe 70:30. This catalyst was also found to exhibit the largest methanol tolerance. © The Electrochemical Society.