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Hydrogen Gas (hydrogen + gas)
Selected AbstractsBiological Conversion of Anglesite (PbSO4) and Lead Waste from Spent Car Batteries to Galena (PbS)BIOTECHNOLOGY PROGRESS, Issue 4 2002Jan Weijma Lead paste, a solid mixture containing PbSO4, PbO2, PbO/Pb(OH)2precipitate, and elemental Pb, is one of the main waste fractions from spent car batteries. Biological sulfidation represents a new process for recovery of lead from this waste. In this process the lead salts in lead paste are converted to galena (PbS) by sulfate-reducing bacteria. This paper investigates a continuous process for sulfidation of anglesite (PbSO4), the main constituent of lead paste, and lead paste, consisting of a laboratory-scale gas-lift bioreactor to which a slurry of anglesite or lead paste was supplied. Sulfate or elemental sulfur was added as an additional sulfur source. Hydrogen gas served as an electron donor for the biological reduction of sulfate and elemental sulfur to sulfide by sulfate- and sulfur-reducing bacteria. Anglesite was almost completely converted to galena at a loading rate of 19 kg of PbSO4m,3day,1, producing a sludge of which the crystalline lead phases consisted of >98% PbS (galena) and 1,2% elemental Pb. With lead paste, stable sulfidation rates of up to 17 kg of lead paste m,3day,1were demonstrated, producing a sludge of which the crystalline lead phases consisted of an estimated >96% PbS, 1,2% elemental Pb, and 1,2% PbO2. [source] FS02.8 Patch testing with gold trichloride can give false test resultsCONTACT DERMATITIS, Issue 3 2004Birgitta Gruvberger Background:, Hydrochloric acid is formed in water solutions of gold trichloride. Hydrochloric acid in contact with aluminium generates hydrogen gas which can reduce and transform trivalent gold to elemental gold. Objective:, To investigate whether patch testing with aqueous gold trichloride can cause false positive (irritant) reactions in patients without contact allergy to gold and false negative reactions in patients with gold allergy. Methods:, 13 patients with and 13 patients without positive patch test reactions to gold sodium thiosulfate were tested with gold trichloride in 2 different vehicles, water and alkaline buffer, using 2 different test techniques, the Finn Chamber technique with aluminium chambers and van der Bend technique with polypropene chambers. Results:, Irritant patch test reactions were obtained with aqueous gold trichloride tested in van der Bend chambers in 10 patients without gold allergy. In gold-allergic patients no positive test reactions were obtained from aqueous gold trichloride in Finn chambers while 2 positive test reactions were obtained from gold trichloride in alkaline buffer tested in van der Bend chambers. Conclusion:, If gold trichloride is patch tested in wrong vehicle and with wrong test technique irritant test reactions may occur which can be misinterpreted as positive allergic reactions in patients without gold allergy as well as negative reactions in patients with gold allergy. [source] Quasi-two-dimensional electrodeposition growth of Pb0.5Sn0.5 alloyCRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2006Bin Sun Abstract Electrodeposition of Pb0.5Sn0.5 alloy is carried out in a quasi-2D electrochemical cell. As the growth proceeds the morphologies of the deposits transit from cake-like to branched and finally to the compact morphology. We show that these morphological transitions arise from the changes in the transport mechanisms of the ions in the electrolyte cell. In addition, it is found that the current density on the growth interface can vary spontaneously due to the irregular shape of the deposit and the generation of hydrogen gas. It causes the formation of the complex microstructure with non-uniform composition. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The N -Acylated Derivatives of Parent Complex [{(,-SCH2)2NH}Fe2(CO)6] as Active Site Models of Fe-Only Hydrogenases: Synthesis, Characterization, and Related PropertiesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2008Li-Cheng Song Abstract A series of N -acylated diiron azadithiolate complexes as H-cluster models was synthesized and structurally characterized. Treatment of parent complex [{(,-SCH2)2NH}Fe2(CO)6] (A) with 2-chloroacetic acid in the presence of dicyclohexylcarbodiimide or with 2-chloroacetyl chloride in the presence of Et3N gave N -chloroacetyl complex [{(,-SCH2)2NC(O)CH2Cl}Fe2(CO)6] (1). Further treatment of 1 with MeC(O)SK afforded N -acetylthioacetyl complex [{(,-SCH2)2NC(O)CH2SC(O)Me}Fe2(CO)6] (2). N -Ethoxylcarbonylacetyl complex [{(,-SCH2)2NC(O)CH2CO2Et}Fe2(CO)6] (3) and N-heterocyclic complexes [{(,-SCH2)2NC(O)C4H3Y-2}Fe2(CO)6] (4, Y = O; 5, Y = S) were produced by reactions of A with EtO2CCH2C(O)Cl, 2-furancarbonyl chloride, and 2-thiophenecarbonyl chloride in the presence of pyridine or Et3N. Similarly, N -malonyl complex [{Fe2(CO)6(,-SCH2)2NC(O)}2CH2] (6) and N -carbonylbenzaldehyde complex [{(,-SCH2)2NC(O)C6H4CHO- p}Fe2(CO)6] (7) could be obtained by reaction of A with malonyl dichloride in the presence of pyridine and with p -CHOC6H4C(O)Cl in the presence of Et3N. More interestingly, further reaction of 7 with PhCHO and pyrrole in a 1:3:4 molar ratio in the presence of BF3·OEt2 followed by p -chloranil yielded the first light-driven type of model complex containing an N -carbonylphenylporphyrin moiety [{(,-SCH2)2NC(O)(TPP)}Fe2(CO)6] (8, TPP = tetraphenylporphyrin group). Whereas the molecular structures of 2, 5, and 7 were established by X-ray crystallography, the electrochemical properties of 2,5 as well as the proton reduction to hydrogen gas catalyzed by 2 and 3 were studied by CV techniques.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Measurement of mutual diffusion coefficients of gases by the Taylor method: Measurements on H2,Air,H2,N2, and H2,O2 systemsHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 3 2002Naoki Matsunaga Abstract Mutual diffusion coefficients of hydrogen gas (H2) into air and its component gases (N2 and O2) have been measured in the temperature range of 30 to 180°C and at atmospheric pressure via the Taylor dispersion method. For a H2,N2 system, the composition dependence of the mutual diffusion coefficient has been studied with both H2 and N2 as the carrier gas. The mutual diffusion coefficients for the H2,air and H2,N2 systems are almost the same and smaller than that for the H2,O2 system by about 5%. The present data for the H2,N2 system, corrected to an equimolar composition, agree well with the accurate data reported by the groups of P. J. Dunlop and of R. J. J. Van Heijningen. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(3): 182,193, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10025 [source] Combustion-type hydrogenation of nanostructured Mg-based composites for hydrogen storageINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2009M. V. Lototsky Abstract In this study Reactive Ball Milling in hydrogen gas was used to synthesize nanostructured hydrogenated composites of Mg and V-based alloy. After hydrogen desorption, the nanocomposites exhibited a dramatic facilitation of the rate of H absorption by Mg and reduction of the temperature of onset of hydrogenation. These favourable changes were caused by a synergy of catalytic effect of the V-based alloy on hydrogen absorption by Mg and heat release caused by exothermic hydrogen absorption by the V-based alloy. When the initial interaction temperature exceeded a threshold, rather low, value of 20,125°C, depending on the H2 pressure, composition of the sample and its total amount, a combustion-type hydrogenation took place. With optimal interaction parameters applied, H absorption was completed in just 5,70,s and was accompanied by a significant heat release. The observed features can be utilized to reach fast recharge of the Mg-based H stores and to develop efficient heat management systems. Copyright © 2009 John Wiley & Sons, Ltd. [source] Palladium-Catalyzed Isomerization of exo -Methylenic Allylic AlcoholsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Abstract Treatment of allylic alcohols containing a 1,1-disubstituted alkene with a palladium catalyst and hydrogen gas (1,bar) results in facile isomerization to their corresponding trisubstituted (E)-allylic alcohols, along with small amounts of the corresponding hydrogenated products. [source] A Convenient and Effective Method for the Regioselective Deuteration of AlcoholsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2008Tomohiro Maegawa Abstract The convenient and regioselective deuteration of hydroxy groups on vicinal carbons was achieved by the combination of 5% ruthenium on carbon (Ru/C), hydrogen gas and deuterium oxide (D2O). [source] Influence of [2H]-labelled acetic acid as solvent in the synthesis of [2H]-labelled perhexilineJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 1 2010Søren Christian Schou Abstract Preparation of deuterium-labelled perhexiline from an unsaturated analogue was performed via reduction with deuterium gas and PtO2 in acetic acid. Low incorporation was observed when using acetic acid as solvent (most abundant mass peak was M), but when changing the solvent to deuterium-labelled acetic acid, e.g. acetic acid-OD or acetic acid- d4, a higher incorporation was observed (most abundant mass peak was M). Using hydrogen gas instead of deuterium gas with deuterium-labelled acetic acid, high levels of deuterium incorporation were observed (most abundant mass peak was M). An attempt to reduce a precursor with a fully deuterated pyridine to obtain perhexiline with a higher content of deuterium failed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Fretting fatigue strength of SCM435H steel and SUH660 heat-resistant steel in hydrogen gas environmentLUBRICATION SCIENCE, Issue 3 2008M. Kubota Abstract Utilisation of hydrogen is expected to be one of the solutions against the problems of exhaustion of fossil fuels and reduction of carbon dioxide emissions. Evaluation of the materials for hydrogen utilisation machines is required. The objectives of this study are the characterisation of fretting fatigue strength of low-alloy steel SCM435H and heat-resistant steel SUH660, and the validation of effectiveness of nitriding in hydrogen gas environment. Fretting fatigue tests were conducted up to 3 × 107 cycles. The decrease of fretting fatigue strength in hydrogen gas environment was found at the long-life region exceeding 107 cycles. The amount of the decrease of the fretting fatigue limit at 3 × 107 cycles was 11% for SCM435H and 15% for SUH660. However, at the stress level above the fretting fatigue limit in air, the finite life in hydrogen gas increased more than that in air. The cause of extension of fatigue life was the delay of start of stable crack propagation. Fretting fatigue crack, which was smaller than 200,µm in length, consumed approximately 60% of the fatigue life in hydrogen gas environment. Fretting fatigue crack was steadily propagated after the test was started in air. Observations of the fretted surface showed that the fretting wear process in hydrogen gas environment was dominated by adhesion. Tangential force coefficient was higher in hydrogen gas environment than that in air. It is considered that the adhesion has a close relation to crack initiation in hydrogen gas environment, and as a result, the failure of specimen occurred at a lower stress level comparing the fretting fatigue limit in air. Copyright © 2008 John Wiley & Sons, Ltd. [source] Observations of the quiescent X-ray transients GRS 1124,684 (=GU Mus) and Cen X-4 (=V822 Cen) taken with ULTRACAM on the VLT,MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2010T. Shahbaz ABSTRACT We present high time-resolution multicolour optical observations of the quiescent X-ray transients GRS 1124,684 (=GU Mus) and Cen X-4 (=V822 Cen) obtained with ULTRACAM. Superimposed on the secondary stars' ellipsoidal modulation in both objects are large flares on time-scales of 30,60 min as well as several distinct rapid flares on time-scales of a few minutes, most of which show further variability and unresolved structure. Not significant quasi-periodic oscillations are observed and the power density spectra of GRS 1124,684 and Cen X-4 can be described by a power law. From the colour,colour diagrams of the flare events, for GRS 1124,684 we find that the flares can be described by hydrogen gas with a density of NH, 1024 nucleons cm,2, a temperature of ,8000 K and arising from a radius of ,0.3 R,. Finally we compile the values for the transition radius (the radius of the hot advection-dominated accretion flow) estimated from quasi-periodic oscillations and/or breaks in the power density spectrum for a variety of X-ray transients in different X-ray states. As expected, we find a strong correlation between the bolometric luminosity and the transition radius. [source] Gas chromatography flow rates for determining deuterium/hydrogen ratios of natural gas by gas chromatography/high-temperature conversion/isotope ratio mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2008Wanglu Jia The effects of the gas chromatography flow rate on the determination of the deuterium/hydrogen (D/H) ratios of natural gas utilising gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/TC/IRMS) have been evaluated. In general, the measured ,D values of methane, ethane and propane decrease with increase in column flow rate. When the column flow rate is 1,mL/min or higher, which is commonly used for the determination of D/H ratios of natural gas, the organic H in gas compounds may not be completely converted into hydrogen gas. Based on the results of experiments conducted on a GC column with an i.d. of 0.32,mm, a GC flow rate of 0.6,mL/min is proposed for determining the D/H ratios of natural gas by GC/TC/IRMS. Although this value may be dependent on the instrument conditions used in this work, we believe that correct ,D values of organic compounds with a few carbon atoms are obtained only when relatively low GC flow rates are used for D/H analysis by GC/TC/IRMS. Moreover, as the presence of trace water could significantly affect the determination of D/H ratios, a newly designed inlet liner was used to remove trace water contained in some gas samples. Copyright © 2008 John Wiley & Sons, Ltd. [source] Enhanced hydrogen and 1,3-propanediol production from glycerol by fermentation using mixed culturesBIOTECHNOLOGY & BIOENGINEERING, Issue 6 2009Priscilla A. Selembo Abstract The conversion of glycerol into high value products, such as hydrogen gas and 1,3-propanediol (PD), was examined using anaerobic fermentation with heat-treated mixed cultures. Glycerol fermentation produced 0.28,mol-H2/mol-glycerol (72,mL-H2/g-COD) and 0.69,mol-PD/mol-glycerol. Glucose fermentation using the same mixed cultures produced more hydrogen gas (1.06,mol-H2/mol-glucose) but no PD. Changing the source of inoculum affected gas production likely due to prior acclimation of bacteria to this type of substrate. Fermentation of the glycerol produced from biodiesel fuel production (70% glycerol content) produced 0.31,mol-H2/mol-glycerol (43,mL H2/g-COD) and 0.59,mol-PD/mol-glycerol. These are the highest yields yet reported for both hydrogen and 1,3-propanediol production from pure glycerol and the glycerol byproduct from biodiesel fuel production by fermentation using mixed cultures. These results demonstrate that production of biodiesel can be combined with production of hydrogen and 1,3-propanediol for maximum utilization of resources and minimization of waste. Biotechnol. Bioeng. 2009; 104: 1098,1106. © 2009 Wiley Periodicals, Inc. [source] Microbial Hydrogen Production with Immobilized Sewage SludgeBIOTECHNOLOGY PROGRESS, Issue 5 2002Shu-Yii Wu Municipal sewage sludge was immobilized to produce hydrogen gas under anaerobic conditions. Cell immobilization was essentially achieved by gel entrapment approaches, which were physically or chemically modified by addition of activated carbon (AC), polyurethane (PU), and acrylic latex plus silicone (ALSC). The performance of hydrogen fermentation with a variety of immobilized-cell systems was assessed to identify the optimal type of immobilized cells for practical uses. With sucrose as the limiting carbon source, hydrogen production was more efficient with the immobilized-cell system than with the suspended-cell system, and in both cases the predominant soluble metabolites were butyric acid and acetic acid. Addition of activated carbon into alginate gel (denoted as CA/AC cells) enhanced the hydrogen production rate ( vH2) and substrate-based yield ( YH2/sucrose) by 70% and 52%, respectively, over the conventional alginate-immobilized cells. Further supplementation of polyurethane or acrylic latex/silicone increased the mechanical strength and operation stability of the immobilized cells but caused a decrease in the hydrogen production rate. Kinetic studies show that the dependence of specific hydrogen production rates on the concentration of limiting substrate (sucrose) can be described by Michaelis-Menten model with good agreement. The kinetic analysis suggests that CA/AC cells may contain higher concentration of active biocatalysts for hydrogen production, while PU and ALSC cells had better affinity to the substrate. Acclimation of the immobilized cells led to a remarkable enhancement in vH2 with a 25-fold increase for CA/AC and ca. 10- to 15-fold increases for PU and ALSC cells. However, the ALSC cells were found to have better durability than PU and CA/AC cells as they allowed stable hydrogen production for over 24 repeated runs. [source] Detection Methods for Irradiated FoodsCOMPREHENSIVE REVIEWS IN FOOD SCIENCE AND FOOD SAFETY, Issue 1 2009Sulaxana Kumari Chauhan ABSTRACT:, Proper control of irradiation processing of food is very critical to facilitate international trade of irradiated foods and to enhance consumer confidence, consumer choice, and safety. Analytical detection of radiation-processing of food is very important to implement quality control at all levels. An ideal detection method should measure a specific radiation effect, which is proportional to the dose and should not be affected by processing parameters and storage conditions or the length of time between irradiation processing and analysis. The detection of irradiated foods is mainly based on radiolysis of lipids, modification of amino acids, modification of DNA, modification of carbohydrates, formation of free radicals, release of hydrogen gas, alterations in microbial load, measurement of biological difference, and other physical methods. [source] | |||||||||||||||||||