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1.
Thin-layer carbon supported Nafion-H catalysts were found to be active and highly selective (S>98%) for the partial oxidation of C1-C3 alkanes, in a three phase catalytic membrane reactor (3PCMR), under mild conditions and in the presence of H2O2. The influences of the catalyst teflon loading and H2O2 concentration on the reaction rate have been evaluated. A reaction pathway, based on the electrophilic hydroxylation of the C-H bond of alkanes with protonated hydrogen peroxide (H3O
2
+
), is discussed. 相似文献
2.
Spherical electrode carbon particles prepared from carbon rods of dry cell batteries have been used to study the attrition behaviour in a bubbling fluidized bed combustor. Experiments have been conducted in a 40 mm I.D. and 1 m high fluidized bed combustor operated at 1 m/s superficial velocity. The bed was operated with nitrogen and with two different oxygen concentrations at 850°C to study the effect of combustion on attrition of these particles. The experimental technique used allowed the time resolution of attrited fines generation, providing detailed curves of attrition rates as a function of time. Attrition rate constants have been evaluated. Results show an enhancement of attrition due to combustion even for spherical, homogeneous and smooth particles. 相似文献
3.
D. Miceli F. Arena A. Parmaliana M. S. Scurrell V. Sokolovskii 《Catalysis Letters》1993,18(3):283-288
Precipitated silica catalysts loaded with either MoO3 (0.2–4.0 wt%) or V2O5 (0.2–5.3 wt%) have been studied in the selective partial oxidation of methane to formaldehyde with molecular oxygen at 520 °C. The functionality of the SiO2 surface towards the formation of HCHO is significantly promoted by V2O5, while it is depressed by the MoO3. 相似文献
4.
Mario E Arena María S Lisi María R Alberto 《Journal of the science of food and agriculture》2013,93(1):142-148
BACKGROUND: Lactobacillus hilgardii, a wine lactic acid bacterium, is able to use arginine, through the arginine deiminase pathway with the formation of citrulline, a precursor of the carcinogen ethyl carbamate. The influence of different Argentine wine varieties (Merlot, Cabernet Sauvignon and Malbec), on bacterial growth and arginine metabolism was examined. Furthermore, the effect of different components normally present in wines on the enzyme activities of the arginine deiminase system was determined. RESULTS: Malbec wine under all conditions assayed (33, 50 and 100% supplemented wine:basal media) showed higher arginine consumption and citrulline production than the other wines, as well as the highest bacterial growth and survival of Lactobacillus hilgardii X1B. Glucose and L ‐malic inhibited both arginine deiminase enzymes while fructose and citric acid only inhibited arginine deiminase. The red wines assayed in this study had different composition, and this is an explanation for the different behavior of the bacterium. CONCLUSION: The highest citrulline production in Malbec wine could be correlated with its lower concentrations of glucose, fructose, citric and phenolic acid than the other wines. Therefore, a wine with lower concentration of these sugars and acids could be dangerous due to the formation of ethyl carbamate precursors. Copyright © 2012 Society of Chemical Industry 相似文献
5.
F. Arena T. Torre A. Venuto F. Frusteri A. Mezzapica A. Paraliana 《Catalysis Letters》2002,80(1-2):69-72
A preparation method of highly effective methane to formaldehyde partial oxidation (MPO) FeOx/SiO2 catalysts (Fe 0.09--0.43 wt%) is reported, based on adsorption-precipitation (ADS/PRC) of FeII ions under controlled conditions. The performance of ADS/PRC catalysts in the MPO reaction at 650 °C has been compared with that of conventional systems prepared by incipient wetness (INC/WET) of silica carriers with aqueous solutions of FeIII. The ADS/PRC method, likely enabling a higher dispersion of the active phase, provides very effective MPO catalysts featuring CH4 turnover frequency (TOF) and HCHO productivity (STYHCHO) values larger than those of the counterpart INC/WET systems. 相似文献
6.
7.
Organic double layers obtained by electrodeposition of a substituted polythiophene followed by spin-coating of a Tetracyanoquinodimethane (TCNQ) electron acceptor layer, are characterized by means of spectrophotometric measurements carried out in the UV-VIS-IR range. According to the optical data, the electron acceptor molecules reduce to the singly ionized state as a consequence of a charge-transfer reaction that takes place at the interface with the electrodeposited polymer, which acts as an electron donor. Rectifying heterojunctions are obtained by depositing the double layers on the top of monocrystalline silicon wafers, and on the top of monocrystalline silicon wafers coated with electrochemically de-doped poly(3,4-ethylendioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS). Current versus voltage measurements performed in the dark and under halogen light irradiation show that the developed heterojunctions exhibit photosensitive charge transport features, promising in view of photovoltaic applications. 相似文献
8.
Denise Bevilaqua Heloisa A. Acciari Fabiana A. Arena Assis V. Benedetti Cecílio S. Fugivara Germano Tremiliosi Filho Oswaldo Garcia Júnior 《Minerals Engineering》2009,22(3):254-262
In this work, the monitoring of the bacterial and chemical dissolution of bornite was evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS); the mineral surface was examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The analysis of CV results allowed attributing the different peaks observed in both direct and reverse potential scanning to the oxidation of bornite to a secondary covellite and its reduction via different non stoichiometric copper sulphides intermediaries. EIS data for bornite were obtained in control medium up to 78 h of immersion, when a cellular suspension of A. ferrooxidans was added and the experiments continued up to a 192 h of test. The EIS response was different when bacteria were added in the beginning of the test or after some hours of immersion in acid solution. The experiments were performed in different cell configurations and a model of the electrode/electrolyte interface. The correspondent equivalent electrical circuit was used to fit impedance spectra for all studied conditions. A common equivalent circuit used for corrosion processes where anodic (degradation of the mineral) and cathodic (oxygen reduction) reactions occur in parallel, together film and biofilm formation was proposed. 相似文献
9.
M E Arena F M Saguir M C Manca de Nadra 《International journal of food microbiology》1999,47(3):203-209
Lactobacillus plantarum N8 and N4 strains isolated from orange degraded L-arginine to citrulline, ornithine and ammonia. Citrulline and ornithine were consumed. Lactobacillus plantarum N4 utilized arginine and ornithine to a higher extent than Lactobacillus plantarum N8. Urea was not detected during arginine degradation, indicating that the amino acid degradation was carried out only by the arginine dihydrolase pathway. Citrulline increased the growth of the two strains, arginine only increased the growth of Lactobacillus plantarum N4. Ornithine did not modify the growth of the strains studied. With different behavior, Lactobacillus plantarum N8 and N4 strains were able to derive energy and ammonia from arginine or citrulline catabolism. This is interesting for microorganisms developing in a stressful environment. 相似文献
10.
In this study we conducted a survey of the concentrations of the major 1,2-dicarbonyl compounds in 40 commercial honey samples from 12 different floral origins. 3-Deoxyglucosone (3-DG), glyoxal (GO), and methylglyoxal (MGO) were measured, using their corresponding quinoxaline derivatives, by high-performance liquid chromatography (HPLC). The analytical performance of the HPLC method for the analysis of 1,2-dicarbonyl compounds was evaluated in terms of linearity, limits of detection (LODs), limits of quantification (LOQs), and precision. Linearity over 2 orders of magnitude, LODs (0.01-0.04 mg/kg), and LOQs (0.03-0.12 mg/kg) were calculated. Instrumental precision, as measured by the repeatability relative standard deviation% (RSDr%), was found to be between 0.22% and 0.55%. Furthermore, the concentrations of factors GO and MGO with respect to 3-DG were also calculated for rapid quantification in honey. In honey samples, the concentrations of 3-DG ranged from 75.9 to 808.6 mg/kg and were significantly higher (up to 100-fold) than those of 5-hydroxymethylfurfural (HMF). Values for GO and MGO were 0.1-10.9 and 0.2-2.9 mg/kg, respectively. The chemical characteristics that most influenced the levels of 1,2-dicarbonyl compounds in honey were found to be pH and total phenols. This was supported by multivariate analysis used to classify different honey types with respect to their chemical characteristics. In addition, both dicarbonyls and phenols are believed to contribute to the development of the final color of honey. 相似文献