Science.gov

Sample records for acetate ethanol h2

  1. Acetate and ethanol production from H2 and CO2 by Moorella sp. using a repeated batch culture.

    PubMed

    Sakai, Shinsuke; Nakashimada, Yutaka; Inokuma, Kentaro; Kita, Masayuki; Okada, Hideki; Nishio, Naomichi

    2005-03-01

    The growth inhibition of Moorella sp. HUC22-1 by undissociated acetic acid was analyzed using a non-competitive inhibition model coupled with a pH inhibition model. In the cells grown on H2 and CO2, the inhibition constant, K(p) of the undissociated acetic acid was 6.2 mM (164 mM as the total acetate at pH 6.2, pKa = 4.795, 55 degrees C), which was 1.5-fold higher than that obtained in cells grown on fructose. When a pH-controlled batch culture was performed using a fermentor at pH 6.2 with H2 and CO2, a maximum of 0.92 g/l of dry cell weight and 339 mM of acetate were produced after 220 h, which were 4.4- and 6.8-fold higher than those produced in the pH-uncontrolled batch culture, respectively. In order to reduce acetate inhibition in the culture medium, a repeated batch culture with cell recycling was performed at a constant pH with H2 and CO2. At a pH of 6.2, the total acetate production reached 840 mmol/l-reactor with 4.7 mmol/l-reactor of total ethanol production after 420 h. When the culture pH was maintained at 5.8, which was the optimum for ethanol production, the total ethanol production reached 15.4 mmol/l-reactor after 430 h, although the total acetate production was decreased to 675 mmol/l-reactor.

  2. Bioconversion of H2/CO 2 by acetogen enriched cultures for acetate and ethanol production: the impact of pH.

    PubMed

    Xu, Shuyun; Fu, Bo; Zhang, Lijuan; Liu, He

    2015-06-01

    Syngas fermentation into ethanol and other bioproducts by mixed cultures is considered a promising biotechnology. Effects of pH on product generation and microbial community during H2/CO2 utilization by acetogen enrichment cultures were investigated in this work. The maximum acetate concentration reached 95.41 mmol L(-1) at pH 7, which was 71.7, 21.8 and 50.9% higher than at pH 5, 9 and 11, respectively. The maximum ethanol concentration at pH 7 was 45.7, 50, 72% higher than that at pH 5, 9 and 11, respectively. The CO dehydrogenase (CODH) gene copy number was highest at pH 7, indicating that metabolically active acetogens reached their highest level at pH 7. The CODH gene copy number at pH 9 was lower than at pH 7, but higher than at pH 5 and 11. Correspondingly, the enrichment cultures at pH 7 had the highest species richness and diversity, while those at pH 9 had the second highest diversity, and those at pH 5 and 11 had the lowest diversity. The shift in microbial community structure and the different active acetogen contents resulting from different pHs were responsible for the differences in acetate and ethanol production.

  3. Manufacturing Ethyl Acetate From Fermentation Ethanol

    NASA Technical Reports Server (NTRS)

    Rohatgi, Naresh K.; Ingham, John D.

    1991-01-01

    Conceptual process uses dilute product of fermentation instead of concentrated ethanol. Low-concentration ethanol, extracted by vacuum from fermentation tank, and acetic acid constitutes feedstock for catalytic reaction. Product of reaction goes through steps that increases ethyl acetate content to 93 percent by weight. To conserve energy, heat exchangers recycle waste heat to preheat process streams at various points.

  4. Energy Conservation Associated with Ethanol Formation from H2 and CO2 in Clostridium autoethanogenum Involving Electron Bifurcation

    PubMed Central

    Mock, Johanna; Zheng, Yanning; Mueller, Alexander P.; Ly, San; Tran, Loan; Segovia, Simon; Nagaraju, Shilpa; Köpke, Michael; Dürre, Peter

    2015-01-01

    ABSTRACT Most acetogens can reduce CO2 with H2 to acetic acid via the Wood-Ljungdahl pathway, in which the ATP required for formate activation is regenerated in the acetate kinase reaction. However, a few acetogens, such as Clostridium autoethanogenum, Clostridium ljungdahlii, and Clostridium ragsdalei, also form large amounts of ethanol from CO2 and H2. How these anaerobes with a growth pH optimum near 5 conserve energy has remained elusive. We investigated this question by determining the specific activities and cofactor specificities of all relevant oxidoreductases in cell extracts of H2/CO2-grown C. autoethanogenum. The activity studies were backed up by transcriptional and mutational analyses. Most notably, despite the presence of six hydrogenase systems of various types encoded in the genome, the cells appear to contain only one active hydrogenase. The active [FeFe]-hydrogenase is electron bifurcating, with ferredoxin and NADP as the two electron acceptors. Consistently, most of the other active oxidoreductases rely on either reduced ferredoxin and/or NADPH as the electron donor. An exception is ethanol dehydrogenase, which was found to be NAD specific. Methylenetetrahydrofolate reductase activity could only be demonstrated with artificial electron donors. Key to the understanding of this energy metabolism is the presence of membrane-associated reduced ferredoxin:NAD+ oxidoreductase (Rnf), of electron-bifurcating and ferredoxin-dependent transhydrogenase (Nfn), and of acetaldehyde:ferredoxin oxidoreductase, which is present with very high specific activities in H2/CO2-grown cells. Based on these findings and on thermodynamic considerations, we propose metabolic schemes that allow, depending on the H2 partial pressure, the chemiosmotic synthesis of 0.14 to 1.5 mol ATP per mol ethanol synthesized from CO2 and H2. IMPORTANCE Ethanol formation from syngas (H2, CO, and CO2) and from H2 and CO2 that is catalyzed by bacteria is presently a much-discussed process for

  5. Elimination of hydrogenase active site assembly blocks H2 production and increases ethanol yield in Clostridium thermocellum

    SciTech Connect

    Biswas, Ranjita; Zheng, Tianyong; Olson, Daniel G.; Lynd, Lee R.; Guss, Adam M.

    2015-02-01

    The native ability of Clostridium thermocellum to rapidly consume cellulose and produce ethanol makes it a leading candidate for a consolidated bioprocessing (CBP) biofuel production strategy. C. thermocellum also synthesizes lactate, formate, acetate, H2, and amino acids that compete with ethanol production for carbon and electrons. Elimination of H2 production could redirect carbon flux towards ethanol production by making more electrons available for acetyl-CoA reduction to ethanol. C. thermocellum encodes four hydrogenases and rather than delete each individually, we targeted a hydrogenase maturase gene (hydG), involved in converting the three [FeFe] hydrogenase apoenzymes into holoenzymes. Further deletion of the [NiFe] hydrogenase (ech) resulted in a mutant that functionally lacks all four hydrogenases. H2 production in hydG ech was undetectable and ethanol yield increased nearly 2-fold compared to wild type. Interestingly, mutant growth improved upon the addition of acetate, which led to increased expression of genes related to sulfate metabolism, suggesting these mutants may use sulfate as a terminal electron acceptor to balance redox reactions. Genomic analysis of hydG revealed a mutation in adhE, resulting in a strain with both NADH- and NADPH-dependent alcohol dehydrogenase activities. While this same adhE mutation is found in ethanol tolerant C. thermocellum strain E50C, hydG and hydG ech are not more ethanol tolerant than wild type, illustrating the complicated interactions between redox balancing and ethanol tolerance in C. thermocellum. The dramatic increase in ethanol production here suggests that targeting protein post-translational modification is a promising new approach for inactivation of multiple enzymes simultaneously for metabolic engineering.

  6. Elimination of hydrogenase active site assembly blocks H2 production and increases ethanol yield in Clostridium thermocellum

    DOE PAGES

    Biswas, Ranjita; Zheng, Tianyong; Olson, Daniel G.; ...

    2015-02-01

    The native ability of Clostridium thermocellum to rapidly consume cellulose and produce ethanol makes it a leading candidate for a consolidated bioprocessing (CBP) biofuel production strategy. C. thermocellum also synthesizes lactate, formate, acetate, H2, and amino acids that compete with ethanol production for carbon and electrons. Elimination of H2 production could redirect carbon flux towards ethanol production by making more electrons available for acetyl-CoA reduction to ethanol. C. thermocellum encodes four hydrogenases and rather than delete each individually, we targeted a hydrogenase maturase gene (hydG), involved in converting the three [FeFe] hydrogenase apoenzymes into holoenzymes. Further deletion of the [NiFe]more » hydrogenase (ech) resulted in a mutant that functionally lacks all four hydrogenases. H2 production in hydG ech was undetectable and ethanol yield increased nearly 2-fold compared to wild type. Interestingly, mutant growth improved upon the addition of acetate, which led to increased expression of genes related to sulfate metabolism, suggesting these mutants may use sulfate as a terminal electron acceptor to balance redox reactions. Genomic analysis of hydG revealed a mutation in adhE, resulting in a strain with both NADH- and NADPH-dependent alcohol dehydrogenase activities. While this same adhE mutation is found in ethanol tolerant C. thermocellum strain E50C, hydG and hydG ech are not more ethanol tolerant than wild type, illustrating the complicated interactions between redox balancing and ethanol tolerance in C. thermocellum. The dramatic increase in ethanol production here suggests that targeting protein post-translational modification is a promising new approach for inactivation of multiple enzymes simultaneously for metabolic engineering.« less

  7. Synthesis of acetic acid via methanol hydrocarboxylation with CO2 and H2

    PubMed Central

    Qian, Qingli; Zhang, Jingjing; Cui, Meng; Han, Buxing

    2016-01-01

    Acetic acid is an important bulk chemical that is currently produced via methanol carbonylation using fossil based CO. Synthesis of acetic acid from the renewable and cheap CO2 is of great importance, but state of the art routes encounter difficulties, especially in reaction selectivity and activity. Here we report a route to produce acetic acid from CO2, methanol and H2. The reaction can be efficiently catalysed by Ru–Rh bimetallic catalyst using imidazole as the ligand and LiI as the promoter in 1,3-dimethyl-2-imidazolidinone (DMI) solvent. It is confirmed that methanol is hydrocarboxylated into acetic acid by CO2 and H2, which accounts for the outstanding reaction results. The reaction mechanism is proposed based on the control experiments. The strategy opens a new way for acetic acid production and CO2 transformation, and represents a significant progress in synthetic chemistry. PMID:27165850

  8. Clostridiumm ljungdahlii, an anaerobic ethanol and acetate producing microorganism

    DOEpatents

    Gaddy, James L.; Clausen, Edgar C.

    1992-01-01

    A newly discovered microorganism was isolated in a biologically pure culture and designated Clostridium ljungdahlii, having the identifying characteristics of ATCC No. 49587. Cultured in an aqueous nutrient medium under anaerobic conditions, this microorganism is capable of producing ethanol and acetate from CO and H.sub.2 O and/or CO.sub.2 and H.sub.2 in synthesis gas. Under optimal growth conditions, the microorganism produces acetate in preference to ethanol. Conversely, under non-growth conditions, ethanol production is favored over acetate.

  9. Clostridiumm ljungdahlii, an anaerobic ethanol and acetate producing microorganism

    DOEpatents

    Gaddy, J.L.; Clausen, E.C.

    1992-12-22

    A newly discovered microorganism was isolated in a biologically pure culture and designated Clostridium ljungdahlii, having the identifying characteristics of ATCC No. 49587. Cultured in an aqueous nutrient medium under anaerobic conditions, this microorganism is capable of producing ethanol and acetate from CO and H[sub 2]O and/or CO[sub 2] and H[sub 2] in synthesis gas. Under optimal growth conditions, the microorganism produces acetate in preference to ethanol. Conversely, under non-growth conditions, ethanol production is favored over acetate. 3 figs.

  10. Ethanol sorption and partial molar volume in cellulose acetate films

    SciTech Connect

    Bolton, B.A.; Kint, S.; Bailey, G.F.; Scherer, J.R.

    1986-03-13

    The absorption characteristics of cellulose acetate (CA398) and cellulose triacetate membranes for ethanol vapor were determined by integrated optical techniques. Changes in the refractive index and film thicknesses are used to calculate the ethanol concentration within the membrane, to calculate the partial molar volume of sorbed ethanol as a function of ethanol concentration, and to estimate the average void volume of the dry film. The refractive index is shown to be very sensitive to the available void space within the membrane. The average total void space for the films considered here was less than 1% of the dry polymer volume. 22 references, 6 figures, 1 table.

  11. Methane production from formate, acetate and H2/CO2; focusing on kinetics and microbial characterization.

    PubMed

    Pan, Xiaofang; Angelidaki, Irini; Alvarado-Morales, Merlin; Liu, Houguang; Liu, Yuhong; Huang, Xu; Zhu, Gefu

    2016-10-01

    For evaluating the methanogenesis from typical methanogenic precursors (formate, acetate and H2/CO2), CH4 production kinetics were investigated at 37±1°C in batch anaerobic digestion tests and stimulated by modified Gompertz model. The results showed that maximum methanation rate from formate, acetate and H2/CO2 were 19.58±0.49, 42.65±1.17 and 314.64±3.58NmL/gVS/d in digested manure system and 6.53±0.31, 132.04±3.96 and 640.16±19.92NmL/gVS/d in sewage sludge system during second generation incubation. Meanwhile the model could not fit well in granular sludge system, while the rate of formate methanation was faster than from H2/CO2 and acetate. Considering both the kinetic results and microbial assay we could conclude that H2/CO2 methanation was the fastest methanogenic step in digested manure and sewage sludge system with Methanomicrobiales as dominant methanogens, while granular sludge with Methanobacteriales as dominant methanogens contributed to the fastest formate methanation.

  12. Short-term effect of acetate and ethanol on methane formation in biogas sludge.

    PubMed

    Refai, Sarah; Wassmann, Kati; Deppenmeier, Uwe

    2014-08-01

    Biochemical processes in biogas plants are still not fully understood. Especially, the identification of possible bottlenecks in the complex fermentation processes during biogas production might provide potential to increase the performance of biogas plants. To shed light on the question which group of organism constitutes the limiting factor in the anaerobic breakdown of organic material, biogas sludge from different mesophilic biogas plants was examined under various conditions. Therefore, biogas sludge was incubated and analyzed in anaerobic serum flasks under an atmosphere of N2/CO2. The batch reactors mirrored the conditions and the performance of the full-scale biogas plants and were suitable test systems for a period of 24 h. Methane production rates were compared after supplementation with substrates for syntrophic bacteria, such as butyrate, propionate, or ethanol, as well as with acetate and H2+CO2 as substrates for methanogenic archaea. Methane formation rates increased significantly by 35 to 126 % when sludge from different biogas plants was supplemented with acetate or ethanol. The stability of important process parameters such as concentration of volatile fatty acids and pH indicate that ethanol and acetate increase biogas formation without affecting normally occurring fermentation processes. In contrast to ethanol or acetate, other fermentation products such as propionate, butyrate, or H2 did not result in increased methane formation rates. These results provide evidence that aceticlastic methanogenesis and ethanol-oxidizing syntrophic bacteria are not the limiting factor during biogas formation, respectively, and that biogas plant optimization is possible with special focus on methanogenesis from acetate.

  13. Enhanced photo-fermentative H2 production using Rhodobacter sphaeroides by ethanol addition and analysis of soluble microbial products

    PubMed Central

    2014-01-01

    Background Biological fermentation routes can provide an environmentally friendly way of producing H2 since they use renewable biomass as feedstock and proceed under ambient temperature and pressure. In particular, photo-fermentation has superior properties in terms of achieving high H2 yield through complete degradation of substrates. However, long-term H2 production data with stable performance is limited, and this data is essential for practical applications. In the present work, continuous photo-fermentative H2 production from lactate was attempted using the purple non-sulfur bacterium, Rhodobacter sphaeroides KD131. As a gradual drop in H2 production was observed, we attempted to add ethanol (0.2% v/v) to the medium. Results As continuous operation went on, H2 production was not sustained and showed a negligible H2 yield (< 0.5 mol H2/mol lactateadded) within two weeks. Electron balance analysis showed that the reason for the gradual drop in H2 production was ascribed to the increase in production of soluble microbial products (SMPs). To see the possible effect of ethanol addition, a batch test was first conducted. The presence of ethanol significantly increased the H2 yield from 1.15 to 2.20 mol H2/mol lactateadded, by suppressing the production of SMPs. The analysis of SMPs by size exclusion chromatography showed that, in the later period of fermentation, more than half of the low molecular weight SMPs (< 1 kDa) were consumed and used for H2 production when ethanol had been added, while the concentration of SMPs continuously increased in the absence of ethanol. It was found that the addition of ethanol facilitated the utilization of reducing power, resulting in an increase in the cellular levels of NAD+ and NADP+. In continuous operation, ethanol addition was effective, such that stable H2 production was attained with an H2 yield of 2.5 mol H2/mol lactateadded. Less than 15% of substrate electrons were used for SMP production, whereas 35% were used in

  14. Production of Specifically Labeled Compounds by Methanobacterium espanolae Grown on H(2)-CO(2) plus [C]Acetate.

    PubMed

    Patel, G B; Sprott, D; Ekiel, I

    1993-04-01

    Methanobacterium espanolae, an acidiphilic methanogen, required acetate for maximal growth on H(2)-CO(2). In the presence of 5 to 15 mM acetate, at a growth pH of 5.5, the mu(max) was 0.05 h. M. espanolae consumed 12.3 mM acetate during 96 h of incubation at 35 degrees C with shaking at 100 rpm. At initial acetate levels of 2.5 to 10.0 mM, the amount of biomass produced was dependent on the amount of acetate in the medium. C nuclear magnetic resonance spectra of protein hydrolysates obtained from cultures grown on [1-C]- or [2-C]acetate indicated that an incomplete tricarboxylic acid pathway, operating in the reductive direction, was functional in this methanogen. The amino acids were labeled with a very high degree of specificity and at greater than 90% enrichment levels. Less than 2% label randomization occurred between positions primarily labeled from either the carboxyl or methyl group of acetate, and very little label was transferred to positions primarily labeled from CO(2). The labeling pattern of carbohydrates was typical for glucogenesis from pyruvate. This methanogen, by virtue of the properties described above and its ability to incorporate all of the available acetate (10 mM or lower) from the growth medium, has advantages over other microorganisms for use in the production of specifically labeled compounds.

  15. Effect of acetic acid in recycling water on ethanol production for cassava in an integrated ethanol-methane fermentation process.

    PubMed

    Yang, Xinchao; Wang, Ke; Zhang, Jianhua; Tang, Lei; Mao, Zhonggui

    2016-11-01

    Recently, the integrated ethanol-methane fermentation process has been studied to prevent wastewater pollution. However, when the anaerobic digestion reaction runs poorly, acetic acid will accumulate in the recycling water. In this paper, we studied the effect of low concentration of acetic acid (≤25 mM) on ethanol fermentation at different initial pH values (4.2, 5.2 or 6.2). At an initial pH of 4.2, ethanol yields increased by 3.0% and glycerol yields decreased by 33.6% as the acetic acid concentration was increased from 0 to 25 mM. Raising the concentration of acetic acid to 25 mM increased the buffering capacity of the medium without obvious effects on biomass production in the cassava medium. Acetic acid was metabolized by Saccharomyces cerevisiae for the reason that the final concentration of acetic acid was 38.17% lower than initial concentration at pH 5.2 when 25 mM acetic acid was added. These results confirmed that a low concentration of acetic acid in the process stimulated ethanol fermentation. Thus, reducing the acetic acid concentration to a controlled low level is more advantageous than completely removing it.

  16. Electrochemical Partial Reforming of Ethanol into Ethyl Acetate Using Ultrathin Co3O4 Nanosheets as a Highly Selective Anode Catalyst

    PubMed Central

    2016-01-01

    Electrochemical partial reforming of organics provides an alternative strategy to produce valuable organic compounds while generating H2 under mild conditions. In this work, highly selective electrochemical reforming of ethanol into ethyl acetate is successfully achieved by using ultrathin Co3O4 nanosheets with exposed (111) facets as an anode catalyst. Those nanosheets were synthesized by a one-pot, templateless hydrothermal method with the use of ammonia. NH3 was demonstrated critical to the overall formation of ultrathin Co3O4 nanosheets. With abundant active sites on Co3O4 (111), the as-synthesized ultrathin Co3O4 nanosheets exhibited enhanced electrocatalytic activities toward water and ethanol oxidations in alkaline media. More importantly, over the Co3O4 nanosheets, the electrooxidation from ethanol to ethyl acetate was so selective that no other oxidation products were yielded. With such a high selectivity, an electrolyzer cell using Co3O4 nanosheets as the anode electrocatalyst and Ni–Mo nanopowders as the cathode electrocatalyst has been successfully built for ethanol reforming. The electrolyzer cell was readily driven by a 1.5 V battery to achieve the effective production of both H2 and ethyl acetate. After the bulk electrolysis, about 95% of ethanol was electrochemically reformed into ethyl acetate. This work opens up new opportunities in designing a material system for building unique devices to generate both hydrogen and high-value organics at room temperature by utilizing electric energy from renewable sources. PMID:27610415

  17. Zymomonas with improved ethanol production in medium containing concentrated sugars and acetate

    DOEpatents

    Caimi, Perry G.; Chou, Yat-Chen; Franden, Mary Ann; Knoke, Kyle; Tao, Luan; Viitanen, Paul V.; Zhang, Min; Zhang, Yuying

    2010-09-28

    Through screening of a Zymomonas mutant library the himA gene was found to be involved in the inhibitory effect of acetate on Zymomonas performance. Xylose-utilizing Zymomonas further engineered to reduce activity of the himA gene were found to have increased ethanol production in comparison to a parental strain, when cultured in medium comprising xylose and acetate.

  18. Anaerobic degradation of lactate by syntrophic associations of methanosarcina barkeri and desulfovibrio species and effect of H2 on acetate degradation

    SciTech Connect

    McInerney, M.J.; Bryant, M.P.

    1981-02-01

    When grown in the absence of added sulfate, cocultures of Desulfovibrio desulfuricans or Desulfovibrio vulgaris with Methanobrevibacter smithii (Methanobacterium ruminantium), which uses H2 and CO2 for methanogenesis, degraded lactate, with the production of acetate and CH4. When D. desulfuricans or D. vulgaris was grown in the absence of added sulfate in coculture with Methanosarcina barkeri (type strain), which uses both H2-CO2 and acetate for methanogenesis, lactate was stoichiometrically degraded to CH4 and presumably to CO2. During the first 12 days of incubation of the D. desulfuricans-M. barkeri coculture, lactate was completely degraded, with almost stoichiometric production of acetate and CH4. Later, acetate was degraded to CH4 and presumably to CO2. In experiments in which 20 mM acetate and 0 to 20 mM lactate were added to D. desulfuricans-M. barkeri cocultures, no detectable degradation of acetate occurred until the lactate was catabolized. The ultimate rate of acetate utilization for methanogenesis was greater for those cocultures receiving the highest levels of lactate. A small amount of H2 was detected in cocultures which contained D. desulfuricans and M. barkeri until after all lactate was degraded. The addition of H2, but not of lactate, to the growth medium inhibited acetate degradation by pure cultures of M. barkeri. Pure cultures of M. barkeri produced CH4 from acetate at a rate equivalent to that observed for cocultures containing M. barkeri. Inocula of M. barkeri grown with H2-CO2 as the methanogenic substrate produced CH4 from acetate at a rate equivalent to that observed for acetate-grown inocula when grown in a rumen fluid-vitamin-based medium but not when grown in a yeast extract-based medium. The results suggest that H2 produced by the Desulfovibrio species during growth with lactate inhibited acetate degradation by M. barkeri. (Refs. 26).

  19. Performance of dairy cows fed high levels of acetic acid or ethanol.

    PubMed

    Daniel, J L P; Amaral, R C; Sá Neto, A; Cabezas-Garcia, E H; Bispo, A W; Zopollatto, M; Cardoso, T L; Spoto, M H F; Santos, F A P; Nussio, L G

    2013-01-01

    Ethanol and acetic acid are common end products from silages. The main objective of this study was to determine whether high concentrations of ethanol or acetic acid in total mixed ration would affect performance in dairy cows. Thirty mid-lactation Holstein cows were grouped in 10 blocks and fed one of the following diets for 7 wk: (1) control (33% Bermuda hay + 67% concentrates), (2) ethanol [control diet + 5% ethanol, dry matter (DM) basis], or (3) acetic acid (control diet + 5% acetic acid, DM basis). Ethanol and acetic acid were diluted in water (1:2) and sprayed onto total mixed rations twice daily before feeding. An equal amount of water was mixed with the control ration. To adapt animals to these treatments, cows were fed only half of the treatment dose during the first week of study. Cows fed ethanol yielded more milk (37.9 kg/d) than those fed the control (35.8 kg/d) or acetic acid (35.3 kg/d) diets, mainly due to the higher DM intake (DMI; 23.7, 22.2, and 21.6 kg/d, respectively). The significant diet × week interaction for DMI, mainly during wk 2 and 3 (when acetic acid reached the full dose), was related to the decrease in DMI observed for the acetic acid treatment. There was a diet × week interaction in excretion of milk energy per DMI during wk 2 and 3, due to cows fed acetic acid sustained milk yield despite lower DMI. Energy efficiency was similar across diets. Blood metabolites (glucose, insulin, nonesterified fatty acids, ethanol, and γ-glutamyl transferase activity) and sensory characteristics of milk were not affected by these treatments. Animal performance suggested similar energy value for the diet containing ethanol compared with other diets. Rumen conversion of ethanol to acetate and a concomitant increase in methane production might be a plausible explanation for the deviation of the predicted energy value based on the heat of combustion. Therefore, the loss of volatile compounds during the drying process in the laboratory should be

  20. A novel fermentation pathway in an Escherichia coli mutant producing succinic acid, acetic acid, and ethanol.

    SciTech Connect

    Donnelly, M. I.; Millard, C. S.; Clark, D. P.; Chen, M. J.; Rathke, J. W.; Southern Illinois Univ.

    1998-04-01

    Escherichia coli strain NZN111, which is unable to grow fermentatively because of insertional inactivation of the genes encoding pyruvate: formate lyase and the fermentative lactate dehydrogenase, gave rise spontaneously to a chromosomal mutation that restored its ability to ferment glucose. The mutant strain, named AFP111, fermented glucose more slowly than did its wild-type ancestor, strain W1485, and generated a very different spectrum of products. AFP111 produced succinic acid, acetic acid, and ethanol in proportions of approx 2:1:1. Calculations of carbon and electron balances accounted fully for the observed products; 1 mol of glucose was converted to 1 mol of succinic acid and 0.5 mol each of acetic acid and ethanol. The data support the emergence in E.coli of a novel succinic acid:acetic acid:ethanol fermentation pathway.

  1. Modelling bio-electrosynthesis in a reverse microbial fuel cell to produce acetate from CO2 and H2O.

    PubMed

    Kazemi, M; Biria, D; Rismani-Yazdi, H

    2015-05-21

    Bio-electrosynthesis is one of the significant developments in reverse microbial fuel cell technology which is potentially capable of creating organic compounds by combining CO2 with H2O. Accordingly, the main objective in the current study was to present a model of microbial electrosynthesis for producing organic compounds (acetate) based on direct conduction of electrons in biofilms. The proposed model enjoys a high degree of rigor because it can predict variations in the substrate concentration, electrical potential, current density and the thickness of the biofilm. Additionally, coulombic efficiency was investigated as a function of substrate concentration and cathode potential. For a system containing CO2 as the substrate and Sporomusa ovata as the biofilm forming microorganism, an increase in the substrate concentration at a constant potential can lead to a decrease in coulombic efficiency as well as an increase in current density and biofilm thickness. On the other hand, an increase in the surface cathodic voltage at a constant substrate concentration may result in an increase in the coulombic efficiency and a decrease in the current density. The maximum coulombic efficiency was revealed to be 75% at a substrate concentration of 0.025 mmol cm(-3) and 55% at a surface cathodic voltage of -0.3 V producing a high range of acetate production by creating an optimal state in the concentration and potential intervals. Finally, the validity of the model was verified by comparing the obtained results with related experimental findings.

  2. Zymomonas with improved ethanol production in medium containing concentrated sugars and acetate

    DOEpatents

    Caimi, Perry G [Kennett Square, PA; Chou, Yat-Chen [Lakewood, CO; Franden, Mary Ann [Centennial, CO; Knoke, Kyle [Newark, DE; Tao, Luan [Havertown, PA; Viitanen, Paul V [West Chester, PA; Zhang, Min [Lakewood, CO; Zhang, Yuying [New Hope, PA

    2011-03-01

    Through screening of a Zymomonas mutant library the himA gene was found to be involved in the inhibitory effect of acetate on Zymomonas performance. Xylose-utilizing Zymomonas strains further engineered to reduce activity of the himA gene were found to have increased ethanol production in comparison to a parental strain, when cultured in mixed-sugars medium comprising xylose, and, in particular, in the presence of acetate.

  3. Increasing Anaerobic Acetate Consumption and Ethanol Yields in Saccharomyces cerevisiae with NADPH-Specific Alcohol Dehydrogenase

    PubMed Central

    Henningsen, Brooks M.; Hon, Shuen; Covalla, Sean F.; Sonu, Carolina; Argyros, D. Aaron; Barrett, Trisha F.; Wiswall, Erin; Froehlich, Allan C.

    2015-01-01

    Saccharomyces cerevisiae has recently been engineered to use acetate, a primary inhibitor in lignocellulosic hydrolysates, as a cosubstrate during anaerobic ethanolic fermentation. However, the original metabolic pathway devised to convert acetate to ethanol uses NADH-specific acetylating acetaldehyde dehydrogenase and alcohol dehydrogenase and quickly becomes constrained by limited NADH availability, even when glycerol formation is abolished. We present alcohol dehydrogenase as a novel target for anaerobic redox engineering of S. cerevisiae. Introduction of an NADPH-specific alcohol dehydrogenase (NADPH-ADH) not only reduces the NADH demand of the acetate-to-ethanol pathway but also allows the cell to effectively exchange NADPH for NADH during sugar fermentation. Unlike NADH, NADPH can be freely generated under anoxic conditions, via the oxidative pentose phosphate pathway. We show that an industrial bioethanol strain engineered with the original pathway (expressing acetylating acetaldehyde dehydrogenase from Bifidobacterium adolescentis and with deletions of glycerol-3-phosphate dehydrogenase genes GPD1 and GPD2) consumed 1.9 g liter−1 acetate during fermentation of 114 g liter−1 glucose. Combined with a decrease in glycerol production from 4.0 to 0.1 g liter−1, this increased the ethanol yield by 4% over that for the wild type. We provide evidence that acetate consumption in this strain is indeed limited by NADH availability. By introducing an NADPH-ADH from Entamoeba histolytica and with overexpression of ACS2 and ZWF1, we increased acetate consumption to 5.3 g liter−1 and raised the ethanol yield to 7% above the wild-type level. PMID:26386051

  4. Increasing anaerobic acetate consumption and ethanol yields in Saccharomyces cerevisiae with NADPH-specific alcohol dehydrogenase.

    PubMed

    Henningsen, Brooks M; Hon, Shuen; Covalla, Sean F; Sonu, Carolina; Argyros, D Aaron; Barrett, Trisha F; Wiswall, Erin; Froehlich, Allan C; Zelle, Rintze M

    2015-12-01

    Saccharomyces cerevisiae has recently been engineered to use acetate, a primary inhibitor in lignocellulosic hydrolysates, as a cosubstrate during anaerobic ethanolic fermentation. However, the original metabolic pathway devised to convert acetate to ethanol uses NADH-specific acetylating acetaldehyde dehydrogenase and alcohol dehydrogenase and quickly becomes constrained by limited NADH availability, even when glycerol formation is abolished. We present alcohol dehydrogenase as a novel target for anaerobic redox engineering of S. cerevisiae. Introduction of an NADPH-specific alcohol dehydrogenase (NADPH-ADH) not only reduces the NADH demand of the acetate-to-ethanol pathway but also allows the cell to effectively exchange NADPH for NADH during sugar fermentation. Unlike NADH, NADPH can be freely generated under anoxic conditions, via the oxidative pentose phosphate pathway. We show that an industrial bioethanol strain engineered with the original pathway (expressing acetylating acetaldehyde dehydrogenase from Bifidobacterium adolescentis and with deletions of glycerol-3-phosphate dehydrogenase genes GPD1 and GPD2) consumed 1.9 g liter(-1) acetate during fermentation of 114 g liter(-1) glucose. Combined with a decrease in glycerol production from 4.0 to 0.1 g liter(-1), this increased the ethanol yield by 4% over that for the wild type. We provide evidence that acetate consumption in this strain is indeed limited by NADH availability. By introducing an NADPH-ADH from Entamoeba histolytica and with overexpression of ACS2 and ZWF1, we increased acetate consumption to 5.3 g liter(-1) and raised the ethanol yield to 7% above the wild-type level.

  5. Acetate as an active metabolite of ethanol: studies of locomotion, loss of righting reflex, and anxiety in rodents.

    PubMed

    Pardo, Marta; Betz, Adrienne J; San Miguel, Noemí; López-Cruz, Laura; Salamone, John D; Correa, Mercè

    2013-01-01

    IT HAS BEEN POSTULATED THAT A NUMBER OF THE CENTRAL EFFECTS OF ETHANOL ARE MEDIATED VIA ETHANOL METABOLITES: acetaldehyde and acetate. Ethanol is known to produce a large variety of behavioral actions such anxiolysis, narcosis, and modulation of locomotion. Acetaldehyde contributes to some of those effects although the contribution of acetate is less known. In the present studies, rats and mice were used to assess the acute and chronic effects of acetate after central or peripheral administration. Male Sprague-Dawley rats were used for the comparison between central (intraventricular, ICV) and peripheral (intraperitoneal, IP) administration of acute doses of acetate on locomotion. CD1 male mice were used to study acute IP effects of acetate on locomotion, and also the effects of chronic oral consumption of acetate (0, 500, or 1000 mg/l, during 7, 15, 30, or 60 days) on ethanol- (1.0, 2.0, 4.0, or 4.5 g/kg, IP) induced locomotion, anxiolysis, and loss of righting reflex (LORR). In rats, ICV acetate (0.7-2.8 μmoles) reduced spontaneous locomotion at doses that, in the case of ethanol and acetaldehyde, had previously been shown to stimulate locomotion. Peripheral acute administration of acetate also suppressed locomotion in rats (25-100 mg/kg), but not in mice. In addition, although chronic administration of acetate during 15 days did not have an effect on spontaneous locomotion in an open field, it blocked ethanol-induced locomotion. However, ethanol-induced anxiolysis was not affected by chronic administration of acetate. Chronic consumption of acetate (up to 60 days) did not have an effect on latency to, or duration of LORR induced by ethanol, but significantly increased the number of mice that did not achieve LORR. The present work provides new evidence supporting the hypothesis that acetate should be considered a centrally-active metabolite of ethanol that contributes to some behavioral effects of this alcohol, such as motor suppression.

  6. Interaction effects of lactic acid and acetic acid at different temperatures on ethanol production by Saccharomyces cerevisiae in corn mash.

    PubMed

    Graves, Tara; Narendranath, Neelakantam V; Dawson, Karl; Power, Ronan

    2007-01-01

    The combined effects of lactic acid and acetic acid on ethanol production by S. cerevisiae in corn mash, as influenced by temperature, were examined. Duplicate full factorial experiments (three lactic acid concentrations x three acetic acid concentrations) were performed to evaluate the interaction between lactic and acetic acids on the ethanol production of yeast at each of the three temperatures, 30, 34, and 37 degrees C. Corn mash at 30% dry solids adjusted to pH 4 after lactic and acetic acid addition was used as the substrate. Ethanol production rates and final ethanol concentrations decreased (P<0.001) progressively as the concentration of combined lactic and acetic acids in the corn mash increased and the temperature was raised from 30 to 37 degrees C. At 30 degrees C, essentially no ethanol was produced after 96 h when 0.5% w/v acetic acid was present in the mash (with 0.5, 2, and 4% w/v lactic acid). At 34 and 37 degrees C, the final concentrations of ethanol produced by the yeast were noticeably reduced by the presence of 0.3% w/v acetic acid and >or=2% w/v lactic acid. It can be concluded that, as in previous studies with defined media, lactic acid and acetic acid act synergistically to reduce ethanol production by yeast in corn mash. In addition, the inhibitory effects of combined lactic and acetic acid in corn mash were more apparent at elevated temperatures.

  7. Determinations of ethanol, acetaldehyde and acetate in blood and urine during alcohol oxidation in man.

    PubMed

    Tsukamoto, S; Muto, T; Nagoya, T; Shimamura, M; Saito, M; Tainaka, H

    1989-01-01

    Blood and urine samples were analyzed for ethanol, acetaldehyde and acetate during alcohol oxidation in Japanese men by head space gas chromatography, following the consumption of 16 ml/kg of beer during a 20 min period. The maximum level of blood/urine ethanol was found to be 15-17 mM (20-22 mM), while that of acetaldehyde in a flusher and in non-flushers was 20 microM (52 microM) and 2-5 microM (10-13 microM), respectively. Acetate levels in these groups ranged from 0.2 mM (0.1 mM) to 0.8 mM (1.0 mM). Blood ethanol levels were dose dependent, whereas acetaldehyde and acetate levels reflected individual metabolic rates. The relative concentrations of ethanol and acetaldehyde in blood and that of acetate in alcohol metabolism could be summarized as follows: 7500 (15 mM): 1-3 (2-5 microM); 250-400 (0.5-0.8 mM) for non-flushers; and 7500 (15 mM): 5-10 (10-20 microM): 250-400 (0.5-0.8 mM) for a flusher.

  8. Detoxification of biomass derived acetate via metabolic conversion to ethanol, acetone, isopropanol, or ethyl acetate

    DOEpatents

    Sillers, William Ryan; Van Dijken, Hans; Licht, Steve; Shaw, IV, Arthur J.; Gilbert, Alan Benjamin; Argyros, Aaron; Froehlich, Allan C.; McBride, John E.; Xu, Haowen; Hogsett, David A.; Rajgarhia, Vineet B.

    2017-03-28

    One aspect of the invention relates to a genetically modified thermophilic or mesophilic microorganism, wherein a first native gene is partially, substantially, or completely deleted, silenced, inactivated, or down-regulated, which first native gene encodes a first native enzyme involved in the metabolic production of an organic acid or a salt thereof, thereby increasing the native ability of said thermophilic or mesophilic microorganism to produce lactate or acetate as a fermentation product. In certain embodiments, the aforementioned microorganism further comprises a first non-native gene, which first non-native gene encodes a first non-native enzyme involved in the metabolic production of lactate or acetate. Another aspect of the invention relates to a process for converting lignocellulosic biomass to lactate or acetate, comprising contacting lignocellulosic biomass with a genetically modified thermophilic or mesophilic microorganism.

  9. Screening and characterization of ethanol-tolerant and thermotolerant acetic acid bacteria from Chinese vinegar Pei.

    PubMed

    Chen, Yang; Bai, Ye; Li, Dongsheng; Wang, Chao; Xu, Ning; Hu, Yong

    2016-01-01

    Acetic acid bacteria (AAB) are important microorganisms in the vinegar industry. However, AAB have to tolerate the presence of ethanol and high temperatures, especially in submerged fermentation (SF), which inhibits AAB growth and acid yield. In this study, seven AAB that are tolerant to temperatures above 40 °C and ethanol concentrations above 10% (v/v) were isolated from Chinese vinegar Pei. All the isolated AAB belong to Acetobacter pasteurianus according to 16S rDNA analysis. Among all AAB, AAB4 produced the highest acid yield under high temperature and ethanol test conditions. At 4% ethanol and 30-40 °C temperatures, AAB4 maintained an alcohol-acid transform ratio of more than 90.5 %. High alcohol-acid transform ratio was still maintained even at higher temperatures, namely, 87.2, 77.1, 14.5 and 2.9% at 41, 42, 43 and 44 °C, respectively. At 30 °C and different initial ethanol concentrations (4-10%), the acid yield by AAB4 increased gradually, although the alcohol-acid transform ratio decreased to some extent. However, 46.5, 8.7 and 0.9% ratios were retained at ethanol concentrations of 11, 12 and 13%, respectively. When compared with AS1.41 (an AAB widely used in China) using a 10 L fermentor, AAB4 produced 42.0 g/L acetic acid at 37 °C with 10% ethanol, whereas AS1.41 almost stopped producing acetic acid. In conclusion, these traits suggest that AAB4 is a valuable strain for vinegar production in SF.

  10. Enhancement of acetate productivity in a thermophilic (55 °C) hollow-fiber membrane biofilm reactor with mixed culture syngas (H2/CO2) fermentation.

    PubMed

    Wang, Yun-Qi; Yu, Shi-Jin; Zhang, Fang; Xia, Xiu-Yang; Zeng, Raymond J

    2017-03-01

    Conversion of organic wastes to syngas is an attractive way to utilize wastes. The produced syngas can be further used to produce a variety of chemicals. In this study, a hollow-fiber membrane biofilm reactor with mix cultures was operated at 55 °C to convert syngas (H2/CO2) into acetate. A high concentration of acetate (42.4 g/L) was reached in batch experiment while a maximum acetate production rate of 10.5 g/L/day was achieved in the continuous-flow mode at hydraulic retention time (HRT) of 1 day. Acetate was the main product in both batch and continuous-flow experiments. n-Butyrate was the other byproduct in the reactor. Acetate accounted for more than 98.5 and 99.1% of total volatile fatty acids in batch and continuous modes, respectively. Illumina Miseq high-throughput sequencing results showed that microorganisms were highly purified and enriched in the reactor. The main genus was Thermoanaerobacterium (66% of relative abundance), which was usually considered as H2 producer in the literature, however, likely played a role as a H2 consumer in this study. This study provides a new method to generate the high producing rate and purity of acetate from syngas.

  11. Elimination of acetate production to improve ethanol yield during continuous synthesis gas fermentation by engineered biocatalyst Clostridium sp. MTEtOH550.

    PubMed

    Berzin, Vel; Kiriukhin, Michael; Tyurin, Michael

    2012-05-01

    Acetogen strain Clostridum sp. MT653 produced acetate 273 mM (p < 0.005) and ethanol 250 mM (p < 0.005) from synthesis gas blend mixture of 64% CO and 36% H(2). Clostridum sp. MT653 was metabolically engineered to the biocatalyst strain Clostridium sp. MTEtOH550. The biocatalyst increased ethanol yield to 590 mM with no acetate production during single-stage continuous syngas fermentation due to expression of synthetic adh cloned in a multi-copy number expression vector. The acetate production was eliminated by inactivation of the pta gene in Clostridium sp. MTEtOH550. Gene introduction and gene elimination were achieved only using Syngas Biofuels Energy, Inc. electroporation generator. The electrotransformation efficiencies were 8.0 ± 0.2 × 10(6) per microgram of transforming DNA of the expression vector at cell viability ~15%. The frequency of suicidal vector integration to inactivate pta was ~10(-5) per the number of recipient cells. This is the first report on elimination of acetate production and overexpression of synthetic adh gene to engineer acetogen biocatalyst for selective biofuel ethanol production during continuous syngas fermentation.

  12. Enzymatic production of ethanol from cellulose using soluble cellulose acetate as an intermediate

    SciTech Connect

    Downing, K.M.; Ho, C.S.; Zabriskie, D.W.

    1987-01-01

    A two-stage process for the enzymatic conversion of cellulose to ethanol is proposed as an alternative to currently incomplete and relatively slow enzymatic conversion processes employing natural insoluble cellulose. This alternative approach is designed to promote faster and more complete conversion of cellulose to fermentable sugars through the use of a homogeneous enzymatic hydrolysis reaction. Cellulose is chemically dissolved in the first stage to form water-soluble cellulose acetate (WSCA). The WSCA is then converted to ethanol in a simultaneous saccharification-fermentation with Pestalotiopsis westerdijkii enzymes (containing cellulolytic and acetyl esterase components) and yeast.

  13. FeCl3·6H2O, a catalyst for the diastereoselective synthesis of cis-isoxazolidines from N-protected δ-hydroxylamino allylic acetates.

    PubMed

    Cornil, Johan; Guérinot, Amandine; Reymond, Sébastien; Cossy, Janine

    2013-10-18

    An ecofriendly and diastereoselective synthesis of cis-3,5-disubstituted isoxazolidines through the FeCl3·6H2O-catalyzed cyclization of δ-hydroxylamino allylic acetates is described. The synthetic potential of these products is highlighted by the preparation of several functionalized 1,3-amino alcohol precursors.

  14. High temperature stimulates acetic acid accumulation and enhances the growth inhibition and ethanol production by Saccharomyces cerevisiae under fermenting conditions.

    PubMed

    Woo, Ji-Min; Yang, Kyung-Mi; Kim, Sae-Um; Blank, Lars M; Park, Jin-Byung

    2014-07-01

    Cellular responses of Saccharomyces cerevisiae to high temperatures of up to 42 °C during ethanol fermentation at a high glucose concentration (i.e., 100 g/L) were investigated. Increased temperature correlated with stimulated glucose uptake to produce not only the thermal protectant glycerol but also ethanol and acetic acid. Carbon flux into the tricarboxylic acid (TCA) cycle correlated positively with cultivation temperature. These results indicate that the increased demand for energy (in the form of ATP), most likely caused by multiple stressors, including heat, acetic acid, and ethanol, was matched by both the fermentation and respiration pathways. Notably, acetic acid production was substantially stimulated compared to that of other metabolites during growth at increased temperature. The acetic acid produced in addition to ethanol seemed to subsequently result in adverse effects, leading to increased production of reactive oxygen species. This, in turn, appeared to cause the specific growth rate, and glucose uptake rate reduced leading to a decrease of the specific ethanol production rate far before glucose depletion. These results suggest that adverse effects from heat, acetic acid, ethanol, and oxidative stressors are synergistic, resulting in a decrease of the specific growth rate and ethanol production rate and, hence, are major determinants of cell stability and ethanol fermentation performance of S. cerevisiae at high temperatures. The results are discussed in the context of possible applications.

  15. Application of acetate buffer in pH adjustment of sorghum mash and its influence on fuel ethanol fermentation.

    PubMed

    Zhao, Renyong; Bean, Scott R; Crozier-Dodson, Beth Ann; Fung, Daniel Y C; Wang, Donghai

    2009-01-01

    A 2 M sodium acetate buffer at pH 4.2 was tried to simplify the step of pH adjustment in a laboratory dry-grind procedure. Ethanol yields or conversion efficiencies of 18 sorghum hybrids improved significantly with 2.0-5.9% (3.9% on average) of relative increases when the method of pH adjustment changed from traditional HCl to the acetate buffer. Ethanol yields obtained using the two methods were highly correlated (R (2) = 0.96, P < 0.0001), indicating that the acetate buffer did not influence resolution of the procedure to differentiate sorghum hybrids varying in fermentation quality. Acetate retarded the growth of Saccharomyces cerevisiae, but did not affect the overall fermentation rate. With 41-47 mM of undissociated acetic acid in mash of a sorghum hybrid at pH 4.7, rates of glucose consumption and ethanol production were inhibited during exponential phase but promoted during stationary phase. The maximum growth rate constants (mu(max)) were 0.42 and 0.32 h(-1) for cells grown in mashes with pH adjusted by HCl and the acetate buffer, respectively. Viable cell counts of yeast in mashes with pH adjusted by the acetate buffer were 36% lower than those in mashes adjusted by HCl during stationary phase. Coupled to a 5.3% relative increase in ethanol, a 43.6% relative decrease in glycerol was observed, when the acetate buffer was substituted for HCl. Acetate helped to transfer glucose to ethanol more efficiently. The strain tested did not use acetic acid as carbon source. It was suggested that decreased levels of ATP under acetate stress stimulate glycolysis to ethanol formation, increasing its yield at the expense of biomass and glycerol production.

  16. Saccharification behavior of cellulose acetate during enzymatic processing for microbial ethanol production.

    PubMed

    Hama, Shinji; Nakano, Kohsuke; Onodera, Kaoru; Nakamura, Masashi; Noda, Hideo; Kondo, Akihiko

    2014-04-01

    This study was conducted to realize the potential application of cellulose acetate to enzymatic processing, followed by microbial ethanol fermentation. To eliminate the effect of steric hindrance of acetyl groups on the action of cellulase, cellulose acetate was subjected to deacetylation in the presence of 1N sodium hydroxide and a mixture of methanol/acetone, yielding 88.8-98.6% at 5-20% substrate loadings during a 48h saccharification at 50°C. Ethanol fermentation using Saccharomyces cerevisiae attained a high yield of 92.3% from the initial glucose concentration of 44.2g/L; however, a low saccharification yield was obtained at 35°C, decreasing efficiency during simultaneous saccharification and fermentation (SSF). Presaccharification at 50°C prior to SSF without increasing the total process time attained the ethanol titers of 19.8g/L (5% substrate), 38.0g/L (10% substrate), 55.9g/L (15% substrate), and 70.9g/L (20% substrate), which show a 12.0-16.2% improvement in ethanol yield.

  17. Efficient sugar release by acetic acid ethanol-based organosolv pretreatment and enzymatic saccharification.

    PubMed

    Zhang, Hongdan; Wu, Shubin

    2014-12-03

    Acetic acid ethanol-based organosolv pretreatment of sugar cane bagasse was performed to enhance enzymatic hydrolysis. The effect of different parameters (including temperature, reaction time, solvent concentration, and acid catalyst dose) on pretreatment prehydrolyzate and subsequent enzymatic digestibility was determined. During the pretreatment process, 11.83 g of xylose based on 100 g of raw material could be obtained. After the ethanol-based pretreatment, the enzymatic hydrolysis was enhanced and the highest glucose yield of 40.99 g based on 100 g of raw material could be obtained, representing 93.8% of glucose in sugar cane bagasse. The maximum total sugar yields occurred at 190 °C, 45 min, 60:40 ethanol/water, and 5% dosage of acetic acid, reaching 58.36 g (including 17.69 g of xylose and 40.67 g of glucose) based on 100 g of raw material, representing 85.4% of total sugars in raw material. Furthermore, characterization of the pretreated sugar cane bagasse using X-ray diffraction and scanning electron microscopy analyses were also developed. The results suggested that ethanol-based organosolv pretreatment could enhance enzymatic digestibilities because of the delignification and removal of xylan.

  18. STABILITY OF MFI ZEOLITE-FILLED PDMS MEMBRANES DURING PERVAPORATIVE ETHANOL RECOVERY FROM AQUEOUS MIXTURES CONTAINING ACETIC ACID

    EPA Science Inventory

    Pervaporation is a potential process for recovering bioethanol produced from biomass fermentation. Fermentation broths contain ethanol, water, and a variety of other compounds, often including carboxylic acids. The effects of acetic acid on long-term pervaporation of aqueous et...

  19. Acetate as an active metabolite of ethanol: studies of locomotion, loss of righting reflex, and anxiety in rodents

    PubMed Central

    Pardo, Marta; Betz, Adrienne J.; San Miguel, Noemí; López-Cruz, Laura; Salamone, John D.; Correa, Mercè

    2013-01-01

    It has been postulated that a number of the central effects of ethanol are mediated via ethanol metabolites: acetaldehyde and acetate. Ethanol is known to produce a large variety of behavioral actions such anxiolysis, narcosis, and modulation of locomotion. Acetaldehyde contributes to some of those effects although the contribution of acetate is less known. In the present studies, rats and mice were used to assess the acute and chronic effects of acetate after central or peripheral administration. Male Sprague-Dawley rats were used for the comparison between central (intraventricular, ICV) and peripheral (intraperitoneal, IP) administration of acute doses of acetate on locomotion. CD1 male mice were used to study acute IP effects of acetate on locomotion, and also the effects of chronic oral consumption of acetate (0, 500, or 1000 mg/l, during 7, 15, 30, or 60 days) on ethanol- (1.0, 2.0, 4.0, or 4.5 g/kg, IP) induced locomotion, anxiolysis, and loss of righting reflex (LORR). In rats, ICV acetate (0.7–2.8 μmoles) reduced spontaneous locomotion at doses that, in the case of ethanol and acetaldehyde, had previously been shown to stimulate locomotion. Peripheral acute administration of acetate also suppressed locomotion in rats (25–100 mg/kg), but not in mice. In addition, although chronic administration of acetate during 15 days did not have an effect on spontaneous locomotion in an open field, it blocked ethanol-induced locomotion. However, ethanol-induced anxiolysis was not affected by chronic administration of acetate. Chronic consumption of acetate (up to 60 days) did not have an effect on latency to, or duration of LORR induced by ethanol, but significantly increased the number of mice that did not achieve LORR. The present work provides new evidence supporting the hypothesis that acetate should be considered a centrally-active metabolite of ethanol that contributes to some behavioral effects of this alcohol, such as motor suppression. PMID:23847487

  20. ETHANOL, ACETIC ACID, AND WATER ADSORPTION FROM BINARY AND TERNARY LIQUID MIXTURES ON HIGH-SILICA ZEOLITES

    EPA Science Inventory

    Adsorption isotherms were measured for ethanol, acetic acid, and water adsorbed on high-silica ZSM-5 zeolite powder from binary and ternary liquid mixtures at room temperature. Ethanol and water adsorption on two high-silica ZSM-5 zeolites with different aluminum contents and a h...

  1. Selective Production of H2 from Ethanol at Low Temperatures over Rh/ZrO2-CeO2 Catalysts

    SciTech Connect

    Roh, Hyun-Seog; Wang, Yong; King, David L.

    2008-07-01

    A series of Rh catalysts on various supports have been applied to H2 production from the bio-ethanol steam reforming reaction. Support plays a very important role on product selectivity at low temperatures (below 450°C). Acidic or basic supports favor ethanol dehydration, while ethanol dehydrogenation is favored over neutral supports at low temperatures. Among the catalysts evaluated in this study, the Rh/Ce-ZrO2 catalyst exhibited the highest H2 yield at 450 °C, which is possibly due to the high oxygen storage capacity of Ce-ZrO2 resulting in efficient transfer of mobile oxygen species from the H2O molecule to the reaction intermediate.

  2. Techno-economic Analysis for the Thermochemical Conversion of Lignocellulosic Biomass to Ethanol via Acetic Acid Synthesis

    SciTech Connect

    Zhu, Yunhua; Jones, Susanne B.

    2009-04-01

    Biomass is a renewable energy resource that can be converted into liquid fuel suitable for transportation applications. As a widely available biomass form, lignocellulosic biomass can have a major impact on domestic transportation fuel supplies and thus help meet the Energy Independence and Security Act renewable energy goals (U.S. Congress 2007). This study performs a techno-economic analysis of the thermo chemical conversion of biomass to ethanol, through methanol and acetic acid, followed by hydrogenation of acetic acid to ethanol. The conversion of syngas to methanol and methanol to acetic acid are well-proven technologies with high conversions and yields. This study was undertaken to determine if this highly selective route to ethanol could provide an already established economically attractive route to ethanol. The feedstock was assumed to be wood chips at 2000 metric ton/day (dry basis). Two types of gasification technologies were evaluated: an indirectly-heated gasifier and a directly-heated oxygen-blown gasifier. Process models were developed and a cost analysis was performed. The carbon monoxide used for acetic acid synthesis from methanol and the hydrogen used for hydrogenation were assumed to be purchased and not derived from the gasifier. Analysis results show that ethanol selling prices are estimated to be $2.79/gallon and $2.81/gallon for the indirectly-heated gasifier and the directly-heated gasifier systems, respectively (1stQ 2008$, 10% ROI). These costs are above the ethanol market price for during the same time period ($1.50 - $2.50/gal). The co-production of acetic acid greatly improves the process economics as shown in the figure below. Here, 20% of the acetic acid is diverted from ethanol production and assumed to be sold as a co-product at the prevailing market prices ($0.40 - $0.60/lb acetic acid), resulting in competitive ethanol production costs.

  3. Effect of pH and lactic or acetic acid on ethanol productivity by Saccharomyces cerevisiae in corn mash.

    PubMed

    Graves, Tara; Narendranath, Neelakantam V; Dawson, Karl; Power, Ronan

    2006-06-01

    The effects of lactic and acetic acids on ethanol production by Saccharomyces cerevisiae in corn mash, as influenced by pH and dissolved solids concentration, were examined. The lactic and acetic acid concentrations utilized were 0, 0.5, 1.0, 2.0, 3.0 and 4.0% w/v, and 0, 0.1, 0.2, 0.4, 0.8 and 1.6% w/v, respectively. Corn mashes (20, 25 and 30% dry solids) were adjusted to the following pH levels after lactic or acetic acid addition: 4.0, 4.5, 5.0 or 5.5 prior to yeast inoculation. Lactic acid did not completely inhibit ethanol production by the yeast. However, lactic acid at 4% w/v decreased (P<0.05) final ethanol concentration in all mashes at all pH levels. In 30% solids mash set at pH < or =5, lactic acid at 3% w/v reduced (P<0.05) ethanol production. In contrast, inhibition by acetic acid increased as the concentration of solids in the mash increased and the pH of the medium declined. Ethanol production was completely inhibited in all mashes set at pH 4 in the presence of acetic acid at concentrations > or =0.8% w/v. In 30% solids mash set at pH 4, final ethanol levels decreased (P<0.01) with only 0.1% w/v acetic acid. These results suggest that the inhibitory effects of lactic acid and acetic acid on ethanol production in corn mash fermentation when set at a pH of 5.0-5.5 are not as great as that reported thus far using laboratory media.

  4. Effect of manganese ions on ethanol fermentation by xylose isomerase expressing Saccharomyces cerevisiae under acetic acid stress.

    PubMed

    Ko, Ja Kyong; Um, Youngsoon; Lee, Sun-Mi

    2016-12-01

    The efficient fermentation of lignocellulosic hydrolysates in the presence of inhibitors is highly desirable for bioethanol production. Among the inhibitors, acetic acid released during the pretreatment of lignocellulose negatively affects the fermentation performance of biofuel producing organisms. In this study, we evaluated the inhibitory effects of acetic acid on glucose and xylose fermentation by a high performance engineered strain of xylose utilizing Saccharomyces cerevisiae, SXA-R2P-E, harboring a xylose isomerase based pathway. The presence of acetic acid severely decreased the xylose fermentation performance of this strain. However, the acetic acid stress was alleviated by metal ion supplementation resulting in a 52% increased ethanol production rate under 2g/L of acetic acid stress. This study shows the inhibitory effect of acetic acid on an engineered isomerase-based xylose utilizing strain and suggests a simple but effective method to improve the co-fermentation performance under acetic acid stress for efficient bioethanol production.

  5. Effects of glucose, ethanol and acetic acid on regulation of ADH2 gene from Lachancea fermentati

    PubMed Central

    Yaacob, Norhayati; Salleh, Abu Bakar; Abdul Rahman, Nor Aini

    2016-01-01

    Background. Not all yeast alcohol dehydrogenase 2 (ADH2) are repressed by glucose, as reported in Saccharomyces cerevisiae. Pichia stipitis ADH2 is regulated by oxygen instead of glucose, whereas Kluyveromyces marxianus ADH2 is regulated by neither glucose nor ethanol. For this reason, ADH2 regulation of yeasts may be species dependent, leading to a different type of expression and fermentation efficiency. Lachancea fermentati is a highly efficient ethanol producer, fast-growing cells and adapted to fermentation-related stresses such as ethanol and organic acid, but the metabolic information regarding the regulation of glucose and ethanol production is still lacking. Methods. Our investigation started with the stimulation of ADH2 activity from S. cerevisiae and L. fermentati by glucose and ethanol induction in a glucose-repressed medium. The study also embarked on the retrospective analysis of ADH2 genomic and protein level through direct sequencing and sites identification. Based on the sequence generated, we demonstrated ADH2 gene expression highlighting the conserved NAD(P)-binding domain in the context of glucose fermentation and ethanol production. Results. An increase of ADH2 activity was observed in starved L. fermentati (LfeADH2) and S. cerevisiae (SceADH2) in response to 2% (w/v) glucose induction. These suggest that in the presence of glucose, ADH2 activity was activated instead of being repressed. An induction of 0.5% (v/v) ethanol also increased LfeADH2 activity, promoting ethanol resistance, whereas accumulating acetic acid at a later stage of fermentation stimulated ADH2 activity and enhanced glucose consumption rates. The lack in upper stream activating sequence (UAS) and TATA elements hindered the possibility of Adr1 binding to LfeADH2. Transcription factors such as SP1 and RAP1 observed in LfeADH2 sequence have been implicated in the regulation of many genes including ADH2. In glucose fermentation, L. fermentati exhibited a bell-shaped ADH2

  6. Bio-conversion of apple pomace into ethanol and acetic acid: Enzymatic hydrolysis and fermentation.

    PubMed

    Parmar, Indu; Rupasinghe, H P Vasantha

    2013-02-01

    Enzymatic hydrolysis of cellulose present in apple pomace was investigated using process variables such as enzyme activity of commercial cellulase, pectinase and β-glucosidase, temperature, pH, time, pre-treatments and end product separation. The interaction of enzyme activity, temperature, pH and time had a significant effect (P<0.05) on release of glucose. Optimal conditions of enzymatic saccharification were: enzyme activity of cellulase, 43units; pectinase, 183units; β-glucosidase, 41units/g dry matter (DM); temperature, 40°C; pH 4.0 and time, 24h. The sugars were fermented using Saccharomyces cerevisae yielding 19.0g ethanol/100g DM. Further bio-conversion using Acetobacter aceti resulted in the production of acetic acid at a concentration of 61.4g/100g DM. The present study demonstrates an improved process of enzymatic hydrolysis of apple pomace to yield sugars and concomitant bioconversion to produce ethanol and acetic acid.

  7. Ethanol, acetic acid, and water adsorption from binary and ternary liquid mixtures on high-silica zeolites.

    PubMed

    Bowen, Travis C; Vane, Leland M

    2006-04-11

    Adsorption isotherms were measured for ethanol, acetic acid, and water adsorbed on high-silica ZSM-5 zeolite powder from binary and ternary liquid mixtures at room temperature. Ethanol and water adsorption on two high-silica ZSM-5 zeolites with different aluminum contents and a high-silica beta zeolite were also compared. The amounts adsorbed were measured using a recently developed technique that accurately measures the changes in adsorbent/liquid mixture density and liquid concentration. This technique allows the adsorption of each compound in a liquid mixture to be measured. Adsorption data for binary mixtures were fit with the dual-site extended Langmuir model, and the parameters were used to predict ternary adsorption isotherms for each compound with reasonable accuracy. In ternary mixtures, acetic acid competed with ethanol and water for adsorption sites and reduced ethanol adsorption more than it reduced water adsorption.

  8. Glucose respiration and fermentation in Zygosaccharomyces bailii and Saccharomyces cerevisiae express different sensitivity patterns to ethanol and acetic acid.

    PubMed

    Fernandes, L; Côrte-Real, M; Loureiro, V; Loureiro-Dias, M C; Leão, C

    1997-10-01

    In the yeast Zygosaccharomyces bailii ISA 1307, respiration and fermentation of glucose were exponentially inhibited by ethanol, both processes displaying similar sensitivity to the alcohol. Moreover, the degree of inhibition on fermentation was of the same magnitude as that reported for Saccharomyces cerevisiae. Acetic acid also inhibited these two metabolic processes in Z. bailii, with the kinetics of inhibition again being exponential. However, inhibition of fermentation was much less pronounced than in S. cerevisiae. The values estimated with Z. bailii for the minimum inhibitory concentration of acetic acid ranged from 100 to 240 mmol 1(-1) total acetic acid compared with values of near zero reported for S. cerevisiae. The inhibitory effects of acetic acid on Z. bailii were not significantly potentiated by ethanol.

  9. Pervaporation of water and ethanol using a cellulose acetate butyrate membrane

    SciTech Connect

    Wu, W.S.; Lau, W.W.Y.; Rangaiah, G.P.; Sourirajan, S. . Dept. of Chemical Engineering)

    1993-10-15

    Okada and Matsuura's transport equations for pervaporation give rise to three fundamental parameters, namely, interfacial saturation vapor pressure P*, liquid transport parameter A/[delta], and vapor transport parameter B/[delta]. The effects of the chemical nature of the membrane material and the upstream operating pressures of 101.3 and 303.9 kPa on the above parameters were investigated from the pervaporation data at laboratory temperature (24 C) for water and ethanol using a cellulose acetate butyrate membrane. The results show that the P. values are essentially unaffected by the upstream pressure, and that they are generally higher than the literature values of saturation vapor pressure at 24 C. Further, the values for A/[delta] and B/[delta] tend to increase with increased upstream pressure for both systems studied. These results are discussed.

  10. Development of cellulose acetate propionate membrane for separation of ethanol and ethyl tert-butyl ether mixtures

    SciTech Connect

    Luo, G.S.; Niang, M.; Schaetzel, P.

    1997-04-01

    For pervaporation separation of ethanol and ethyl tert-butyl ether mixtures, a cellulose acetate propionate membrane was chosen as the experimental membrane because of its high selectivity and good mass fluxes. The properties of the membranes were evaluated by the pervaporation separation of mixtures of ethyl tert-butyl ether/ethanol and the sorption experiments. The experimental results showed that the selectivity and the permeates depend on the ethanol concentration in the feed and the experimental temperature. With increases of the ethanol weight fraction in the feed and the temperature, the total and partial mass fluxes increased. With respect to the temperature, ethanol mass flux obeys the Arrhenius equation. The selectivity of this membrane decreases as the temperature and the ethanol concentration in the feed increase. This membrane shows special characteristics at the azeotropic composition. In the vicinity of the azeotropic point, minimum values of ethanol concentration in the permeate and in sorption solution are obtained. The swelling ratios increase when temperature and the ethanol concentration in the feed are increasing. The ethanol concentration in the sorption solution is also influenced by the temperature and the mixture`s composition. When the temperature increases, the sorption selectivity of the membrane decreases.

  11. Effect of ethanol, acetaldehyde, acetic Acid, and ethylene on changes in respiration and respiratory metabolites in potato tubers.

    PubMed

    Rychter, A; Janes, H W; Chin, C K; Frenkel, C

    1979-07-01

    Ethanol, acetaldehyde, and acetic acid, when applied in a volatile state in air to potato tubers, led to a climacteric-like upsurge in respiration. The respiratory upsurge was markedly enhanced when the volatiles were applied in 100% O(2).Ethanol induced a decline in the level of 2-phosphoglyceric acid and phosphoenolpyruvate while leading to the accumulation of tricarboxylic acid cycle intermediates including isocitrate and alpha-ketoglutarate. The action of these compounds was similar to, but independent of, the action of ethylene.

  12. Optimum Conditions for the Fabrication of Zein/Ag Composite Nanoparticles from Ethanol/H2O Co-Solvents Using Electrospinning

    PubMed Central

    Yang, Seong Baek; Rabbani, Mohammad Mahbub; Ji, Byung Chul; Han, Dong-Wook; Lee, Joon Seok; Kim, Jong Won; Yeum, Jeong Hyun

    2016-01-01

    The optimum conditions for the fabrication of zein/Ag composite nanoparticles from ethanol/H2O cosolvents using electrospinning and the properties of the composite were investigated. The zein/Ag nanoparticles were characterized using field-emission scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis. The antibacterial activity of the zein/Ag composite nanoparticles was also investigated. The XRD patterns and TEM images indicate the coexistence of a zein matrix and well-distributed Ag nanoparticles. PMID:28335358

  13. Behavioral effects of intraventricular injections of low doses of ethanol, acetaldehyde, and acetate in rats: studies with low and high rate operant schedules.

    PubMed

    Arizzi, Maria N; Correa, Merce; Betz, Adrienne J; Wisniecki, Anna; Salamone, John D

    2003-12-17

    Although ethanol is typically classed as a sedative-hypnotic, low doses of ethanol have been shown to stimulate locomotor activity in mice. However, in rats the typical response to peripheral administration of ethanol is a dose-dependent suppression of motor activity and operant responding. The present study was undertaken to determine the effects of intraventricular (ICV) infusions of ethanol, acetaldehyde, and acetate on operant performance in rats. ICV injections of ethanol, acetaldehyde, or acetate were given to rats previously trained on either a differential-reinforcement-of-low-rates-of-responding (DRL) 30-s schedule, which generates low rates of responding, or a fixed ratio 5 (FR5) schedule, which generates relatively high rates. Ethanol, acetaldehyde, and acetate all produced a rate-increasing effect in rats on the DRL 30-s schedule at moderate doses (2.8 and 1.4 micromol, respectively). Acetate also produced a rate-decreasing effect on the DRL 30-s schedule at a larger dose (8.8 micromol). Performance on the FR5 schedule was unaltered by ethanol and acetaldehyde, even at doses as high as 17.6 micromol. However, acetate produced a rate-decreasing effect on the FR5 schedule at doses of 4.4, 5.6, and 8.8 micromol. Central administration of low doses of ethanol and its metabolites can increase operant responding on some schedules in rats. Acetate is the substance that is most potent for producing rate-suppressing effects. These results indicate that the major metabolites of ethanol are pharmacologically active when injected into the brain, and suggest that acetate may mediate some of the rate-suppressing effects of ethanol, such as sedation, ataxia or motor slowing.

  14. Characterization of a recombinant flocculent Saccharomyces cerevisiae strain that co-ferments glucose and xylose: II. influence of pH and acetic acid on ethanol production.

    PubMed

    Matsushika, Akinori; Sawayama, Shigeki

    2012-12-01

    The inhibitory effects of pH and acetic acid on the co-fermentation of glucose and xylose in complex medium by recombinant flocculent Saccharomyces cerevisiae MA-R4 were evaluated. In the absence of acetic acid, the fermentation performance of strain MA-R4 was similar between pH 4.0-6.0, but was negatively affected at pH 2.5. The addition of acetic acid to batch cultures resulted in negligible inhibition of several fermentation parameters at pH 6.0, whereas the interactive inhibition of pH and acetic acid on the maximum cell and ethanol concentrations, and rates of sugar consumption and ethanol production were observed at pH levels below 5.4. The inhibitory effect of acetic acid was particularly marked for the consumption rate of xylose, as compared with that of glucose. With increasing initial acetic acid concentration, the ethanol yield slightly increased at pH 5.4 and 6.0, but decreased at pH values lower than 4.7. Notably, ethanol production was nearly completely inhibited under low pH (4.0) and high acetic acid (150-200 mM) conditions. Together, these results indicate that the inhibitory effects of acetic acid and pH on ethanol fermentation by MA-R4 are highly synergistic, although the inhibition can be reduced by increasing the medium pH.

  15. Carbon monoxide fermentation to ethanol by Clostridium autoethanogenum in a bioreactor with no accumulation of acetic acid.

    PubMed

    Abubackar, Haris Nalakath; Veiga, María C; Kennes, Christian

    2015-06-01

    Fermentation of CO or syngas offers an attractive route to produce bioethanol. However, during the bioconversion, one of the challenges to overcome is to reduce the production of acetic acid in order to minimize recovery costs. Different experiments were done with Clostridium autoethanogenum. With the addition of 0.75 μM tungsten, ethanol production from carbon monoxide increased by about 128% compared to the control, without such addition, in batch mode. In bioreactors with continuous carbon monoxide supply, the maximum biomass concentration reached at pH 6.0 was 109% higher than the maximum achieved at pH 4.75 but, interestingly, at pH 4.75, no acetic acid was produced and the ethanol titer reached a maximum of 867 mg/L with minor amounts of 2,3-butanediol (46 mg/L). At the higher pH studied (pH 6.0) in the continuous gas-fed bioreactor, almost equal amounts of ethanol and acetic acid were formed, reaching 907.72 mg/L and 910.69 mg/L respectively.

  16. Density Functional Investigation of the Adsorption of Isooctane, Ethanol, and Acetic Acid on a Water-Covered Fe(100) Surface

    PubMed Central

    2014-01-01

    The presence of water in biofuels poses the question of how it affects the frictional performance of additives in fuels containing organic substances. To investigate the effect of water on the adsorption of molecules present in fuel and its additives we simulated within the framework of density functional theory the adsorption of ethanol, isooctane (2,2,4-trimethylpentane), and acetic acid on a bare and a water-covered Fe(100) surface. Van der Waals interactions are taken into account in our computations. In those molecules, where dispersion forces contribute significantly to the binding mechanism, the water layer has a stronger screening effect. Additionally, this effect can be enhanced by the presence of polar functional groups in the molecule. Thus, with the introduction of a water layer, the adsorption energy of isooctane and ethanol is reduced but it is increased in the case of the acetic acid. The adsorption configuration of ethanol is changed, while the one of acetic acid is moderately, and for isooctane only very slightly altered. Therefore, the effect of a water layer in the adsorption of organic molecules on an Fe(100) surface strongly depends on the type of bond and consequently, so do the tribological properties. PMID:25243045

  17. Density Functional Investigation of the Adsorption of Isooctane, Ethanol, and Acetic Acid on a Water-Covered Fe(100) Surface.

    PubMed

    Bedolla, Pedro O; Feldbauer, Gregor; Wolloch, Michael; Gruber, Christoph; Eder, Stefan J; Dörr, Nicole; Mohn, Peter; Redinger, Josef; Vernes, András

    2014-09-18

    The presence of water in biofuels poses the question of how it affects the frictional performance of additives in fuels containing organic substances. To investigate the effect of water on the adsorption of molecules present in fuel and its additives we simulated within the framework of density functional theory the adsorption of ethanol, isooctane (2,2,4-trimethylpentane), and acetic acid on a bare and a water-covered Fe(100) surface. Van der Waals interactions are taken into account in our computations. In those molecules, where dispersion forces contribute significantly to the binding mechanism, the water layer has a stronger screening effect. Additionally, this effect can be enhanced by the presence of polar functional groups in the molecule. Thus, with the introduction of a water layer, the adsorption energy of isooctane and ethanol is reduced but it is increased in the case of the acetic acid. The adsorption configuration of ethanol is changed, while the one of acetic acid is moderately, and for isooctane only very slightly altered. Therefore, the effect of a water layer in the adsorption of organic molecules on an Fe(100) surface strongly depends on the type of bond and consequently, so do the tribological properties.

  18. Synergistic Trap Response of the False Stable Fly and Little House Fly (Diptera: Muscidae) to Acetic Acid and Ethanol, Two Principal Sugar Fermentation Volatiles.

    PubMed

    Landolt, Peter J; Cha, Dong H; Zack, Richard S

    2015-10-01

    In an initial observation, large numbers of muscoid flies (Diptera) were captured as nontarget insects in traps baited with solutions of acetic acid plus ethanol. In subsequent field experiments, numbers of false stable fly Muscina stabulans (Fallén) and little house fly Fannia canicularis (L.) trapped with the combination of acetic acid plus ethanol were significantly higher than those trapped with either chemical alone, or in unbaited traps. Flies were trapped with acetic acid and ethanol that had been formulated in the water of the drowning solution of the trap, or dispensed from polypropylene vials with holes in the vial lids for diffusion of evaporated chemical. Numbers of both species of fly captured were greater with acetic acid and ethanol in glass McPhail traps, compared to four other similar wet trap designs. This combination of chemicals may be useful as an inexpensive and not unpleasant lure for monitoring or removing these two pest fly species.

  19. Correlation between urinary 2-methoxy acetic acid and exposure of 2- methoxy ethanol

    PubMed Central

    Shih, T. S.; Liou, S. H.; Chen, C. Y.; Chou, J. S.

    1999-01-01

    OBJECTIVES: To examine the correlation between airborne 2-methoxy ethanol (ME) exposures and the urinary 2-methoxy acetic acid (MAA) and to recommend a biological exposure index (BEI) for ME. METHODS: 8 Hour time weighted average (TWA) personal breathing zone samples and urine samples before and after the shift were collected from Monday to Saturday for 27 workers exposed to ME and on Friday for 30 control workers. RESULTS: No correlation was found between airborne exposure to ME and urinary MAA for nine special operation workers due to the use of personal protective equipment. For 18 regular operation workers, a significant correlation (r = 0.702, p = 0.001) was found between urinary MAA (mg/g creatinine) on Friday at the end of the shift and the weekly mean exposures of ME in a 5 day working week. The proposed BEI, which corresponds to exposure for 5 days and 8 hours a day to 5 ppm, extrapolated from the regression equation is 40 mg MAA/g creatinine. A significant correlation was also found between the weekly increase of urinary MAA (Friday after the shift minus Monday before the shift) and the weekly mean exposures of ME (r = 0.741). The recommended value of the weekly increase of urinary MAA for 5 days repeated exposures of 5 ppm ME is 20 mg/g creatinine. No urinary MAA was detected in workers in the non-exposed control group. CONCLUSIONS: The Friday urinary MAA after the shift or the weekly increase of urinary MAA is a specific and a good biomarker of weekly exposure to ME.   PMID:10658546

  20. High acetone-butanol-ethanol production in pH-stat co-feeding of acetate and glucose.

    PubMed

    Gao, Ming; Tashiro, Yukihiro; Wang, Qunhui; Sakai, Kenji; Sonomoto, Kenji

    2016-08-01

    We previously reported the metabolic analysis of butanol and acetone production from exogenous acetate by (13)C tracer experiments (Gao et al., RSC Adv., 5, 8486-8495, 2015). To clarify the influence of acetate on acetone-butanol-ethanol (ABE) production, we first performed an enzyme assay in Clostridium saccharoperbutylacetonicum N1-4. Acetate addition was found to drastically increase the activities of key enzymes involved in the acetate uptake (phosphate acetyltransferase and CoA transferase), acetone formation (acetoacetate decarboxylase), and butanol formation (butanol dehydrogenase) pathways. Subsequently, supplementation of acetate during acidogenesis and early solventogenesis resulted in a significant increase in ABE production. To establish an efficient ABE production system using acetate as a co-substrate, several shot strategies were investigated in batch culture. Batch cultures with two substrate shots without pH control produced 14.20 g/L butanol and 23.27 g/L ABE with a maximum specific butanol production rate of 0.26 g/(g h). Furthermore, pH-controlled (at pH 5.5) batch cultures with two substrate shots resulted in not only improved acetate consumption but also a further increase in ABE production. Finally, we obtained 15.13 g/L butanol and 24.37 g/L ABE at the high specific butanol production rate of 0.34 g/(g h) using pH-stat co-feeding method. Thus, in this study, we established a high ABE production system using glucose and acetate as co-substrates in a pH-stat co-feeding system with C. saccharoperbutylacetonicum N1-4.

  1. Gypsum (CaSO4·2H2O) Scaling on Polybenzimidazole and Cellulose Acetate Hollow Fiber Membranes under Forward Osmosis

    PubMed Central

    Chen, Si Cong; Su, Jincai; Fu, Feng-Jiang; Mi, Baoxia; Chung, Tai-Shung

    2013-01-01

    We have examined the gypsum (CaSO4·2H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42° ± 14.85° after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 °C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface. PMID:24957062

  2. Gypsum (CaSO4·2H2O) Scaling on Polybenzimidazole and Cellulose Acetate Hollow Fiber Membranes under Forward Osmosis.

    PubMed

    Chen, Si Cong; Su, Jincai; Fu, Feng-Jiang; Mi, Baoxia; Chung, Tai-Shung

    2013-11-08

    We have examined the gypsum (CaSO4·2H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42° ± 14.85° after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 °C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface.

  3. Main and interaction effects of acetic acid, furfural, and p-hydroxybenzoic acid on growth and ethanol productivity of yeasts.

    PubMed

    Palmqvist, E; Grage, H; Meinander, N Q; Hahn-Hägerdal, B

    1999-04-05

    The influence of the factors acetic acid, furfural, and p-hydroxybenzoic acid on the ethanol yield (YEtOH) of Saccharomyces cerevisiae, bakers' yeast, S. cerevisiae ATCC 96581, and Candida shehatae NJ 23 was investigated using a 2(3)-full factorial design with 3 centrepoints. The results indicated that acetic acid inhibited the fermentation by C. shehatae NJ 23 markedly more than by bakers' yeast, whereas no significant difference in tolerance towards the compounds was detected between the S. cerevisiae strains. Furfural (2 g L-1) and the lignin derived compound p-hydroxybenzoic acid (2 g L-1) did not affect any of the yeasts at the cell mass concentration used. The results indicated that the linear model was not adequate to describe the experimental data (the p-values of curvatures were 0.048 for NJ 23 and 0.091 for bakers' yeast). Based on the results from the 2(3)-full factorial experiment, an extended experiment was designed based on a central composite design to investigate the influence of the factors on the specific growth rate (mu), biomass yield (Yx), volumetric ethanol productivity (QEtOH), and YEtOH. Bakers' yeast was chosen in the extended experiment due to its better tolerance towards acetic acid, which makes it a more interesting organism for use in industrial fermentations of lignocellulosic hydrolysates. The inoculum size was reduced in the extended experiment to reduce any increase in inhibitor tolerance that might be due to a large cell inoculum. By dividing the experiment in blocks containing fermentations performed with the same inoculum preparation on the same day, much of the anticipated systematic variation between the experiments was separated from the experimental error. The results of the fitted model can be summarised as follows: mu was decreased by furfural (0-3 g L-1). Furfural and acetic acid (0-10 g L-1) also interacted negatively on mu. Furfural concentrations up to 2 g L-1 stimulated Yx in the absence of acetic acid whereas higher

  4. Ethanol and acetic acid production from carbon monoxide in a Clostridium strain in batch and continuous gas-fed bioreactors.

    PubMed

    Abubackar, Haris Nalakath; Veiga, María C; Kennes, Christian

    2015-01-20

    The effect of different sources of nitrogen as well as their concentrations on the bioconversion of carbon monoxide to metabolic products such as acetic acid and ethanol by Clostridium autoethanogenum was studied. In a first set of assays, under batch conditions, either NH4Cl, trypticase soy broth or yeast extract (YE) were used as sources of nitrogen. The use of YE was found statistically significant (p < 0.05) on the product spectrum in such batch assays. In another set of experiments, three bioreactors were operated with continuous CO supply, in order to estimate the effect of running conditions on products and biomass formation. The bioreactors were operated under different conditions, i.e., EXP1 (pH = 5.75, YE 1g/L), EXP2 (pH = 4.75, YE 1 g/L) and EXP3 (pH = 5.75, YE 0.2 g/L). When compared to EXP2 and EXP3, it was found that EXP1 yielded the maximum biomass accumulation (302.4 mg/L) and products concentrations, i.e., acetic acid (2147.1 mg/L) and ethanol (352.6 mg/L). This can be attributed to the fact that the higher pH and higher YE concentration used in EXP1 stimulated cell growth and did, consequently, also enhance metabolite production. However, when ethanol is the desired end-product, as a biofuel, the lower pH used in EXP2 was more favourable for solventogenesis and yielded the highest ethanol/acetic acid ratio, reaching a value of 0.54.

  5. Ethanol and Acetic Acid Production from Carbon Monoxide in a Clostridium Strain in Batch and Continuous Gas-Fed Bioreactors

    PubMed Central

    Nalakath Abubackar, Haris; Veiga, María C.; Kennes, Christian

    2015-01-01

    The effect of different sources of nitrogen as well as their concentrations on the bioconversion of carbon monoxide to metabolic products such as acetic acid and ethanol by Clostridium autoethanogenum was studied. In a first set of assays, under batch conditions, either NH4Cl, trypticase soy broth or yeast extract (YE) were used as sources of nitrogen. The use of YE was found statistically significant (p < 0.05) on the product spectrum in such batch assays. In another set of experiments, three bioreactors were operated with continuous CO supply, in order to estimate the effect of running conditions on products and biomass formation. The bioreactors were operated under different conditions, i.e., EXP1 (pH = 5.75, YE 1g/L), EXP2 (pH = 4.75, YE 1 g/L) and EXP3 (pH = 5.75, YE 0.2 g/L). When compared to EXP2 and EXP3, it was found that EXP1 yielded the maximum biomass accumulation (302.4 mg/L) and products concentrations, i.e., acetic acid (2147.1 mg/L) and ethanol (352.6 mg/L). This can be attributed to the fact that the higher pH and higher YE concentration used in EXP1 stimulated cell growth and did, consequently, also enhance metabolite production. However, when ethanol is the desired end-product, as a biofuel, the lower pH used in EXP2 was more favourable for solventogenesis and yielded the highest ethanol/acetic acid ratio, reaching a value of 0.54. PMID:25608591

  6. Hydrogen production with effluent from an ethanol-H2-coproducing fermentation reactor using a single-chamber microbial electrolysis cell.

    PubMed

    Lu, Lu; Ren, Nanqi; Xing, Defeng; Logan, Bruce E

    2009-06-15

    Hydrogen can be produced by bacterial fermentation of sugars, but substrate conversion to hydrogen is incomplete. Using a single-chamber microbial electrolysis cell (MEC), we show that additional hydrogen can be produced from the effluent of an ethanol-type dark-fermentation reactor. An overall hydrogen recovery of 83+/-4% was obtained using a buffered effluent (pH 6.7-7.0), with a hydrogen production rate of 1.41+/-0.08 m(3) H(2)/m(3) reactor/d, at an applied voltage of E(ap)=0.6 V. When the MEC was combined with the fermentation system, the overall hydrogen recovery was 96%, with a production rate of 2.11 m(3) H(2)/m(3)/d, corresponding to an electrical energy efficiency of 287%. High cathodic hydrogen recoveries (70+/-5% to 94+/-4%) were obtained at applied voltages of 0.5-0.8 V due to shorter cycle times, and repression of methanogen growth through exposure of the cathode to air after each cycle. Addition of a buffer to the fermentation effluent was critical to MEC performance as there was little hydrogen production using unbuffered effluent (0.0372 m(3) H(2)/m(3)/d at E(ap)=0.6 V, pH 4.5-4.6). These results demonstrate that hydrogen yields from fermentation can be substantially increased by using MECs.

  7. Nematocyst discharge in Pelagia noctiluca (Cnidaria, Scyphozoa) oral arms can be affected by lidocaine, ethanol, ammonia and acetic acid.

    PubMed

    Morabito, Rossana; Marino, Angela; Dossena, Silvia; La Spada, Giuseppa

    2014-06-01

    Nematocyst discharge and concomitant delivery of toxins is triggered to perform both defence and predation strategies in Cnidarians, and may lead to serious local and systemic reactions in humans. Pelagia noctiluca (Cnidaria, Scyphozoa) is a jellyfish particularly abundant in the Strait of Messina (Italy). After accidental contact with this jellyfish, not discharged nematocysts or even fragments of tentacles or oral arms may tightly adhere to the human skin and, following discharge, severely increase pain and the other adverse consequences of the sting. The aim of the present study is to verify if the local anesthetic lidocaine and other compounds, like alcohols, acetic acid and ammonia, known to provide pain relief after jellyfish stings, may also affect in situ discharge of nematocysts. Discharge was induced by a combined physico-chemical stimulation of oral arms by chemosensitizers (such as N-acetylated sugars, aminoacids, proteins and nucleotides), in the presence or absence of 1% lidocaine, 70% ethanol, 5% acetic acid or 20% ammonia, followed by mechanical stimulation by a non-vibrating test probe. The above mentioned compounds failed to induce discharge per se, and dramatically impaired the chemosensitizer-induced discharge response. We therefore suggest that prompt local treatment of the stung epidermis with lidocaine, acetic acid, ethanol and ammonia may provide substantial pain relief and help in reducing possible harmful local and systemic adverse reaction following accidental contact with P. noctiluca specimens.

  8. Infrared Spectra of M^+(2-AMINO-1-PHENYL ETHANOL)(H_2O)_{n=0-2}Ar (M=Na, K)

    NASA Astrophysics Data System (ADS)

    Nicely, Amy L.; Lisy, James M.

    2009-06-01

    A balance of competing electrostatic and hydrogen bonding interactions directs the structure of hydrated gas-phase cluster ions. Because of this, a biologically relevant model of cluster structures should include the effects of surrounding water molecules and metal ions such as sodium and potassium, which are found in high concentrations in the bloodstream. The molecule 2-amino-1-phenyl ethanol (APE) serves as a model for the neurotransmitters ephedrine and adrenaline. The neutral APE molecule contains an internal hydrogen bond between the amino and hydroxyl groups. In the M^+(APE) complex, the cation can either interrupt the internal hydrogen bond or position itself above the phenyl group, leaving the internal hydrogen bond intact. The former is preferred based on DFT calculations (B3LYP/6-31+G*) for both K^+ and Na^+ across the entire range from 0-400K, but infrared photodissociation (IRPD) spectra indicate a preference for the latter configuration at low temperatures. The IRPD spectra of M^+(H_2O)_{n=1-2} and M^+(H_2O)_{n=0-2}Ar (M=Na, K) will be presented along with parallel DFT and thermodynamics calculations to assist with the identification of the isomers present in each experiment.

  9. Effect of acetic acid and pH on the cofermentation of glucose and xylose to ethanol by a genetically engineered strain of Saccharomyces cerevisiae.

    PubMed

    Casey, Elizabeth; Sedlak, Miroslav; Ho, Nancy W Y; Mosier, Nathan S

    2010-06-01

    A current challenge of the cellulosic ethanol industry is the effect of inhibitors present in biomass hydrolysates. Acetic acid is an example of one such inhibitor that is released during the pretreatment of hemicellulose. This study examined the effect of acetic acid on the cofermentation of glucose and xylose under controlled pH conditions by Saccharomyces cerevisiae 424A(LNH-ST), a genetically engineered industrial yeast strain. Acetic acid concentrations of 7.5 and 15 g L(-1), representing the range of concentrations expected in actual biomass hydrolysates, were tested under controlled pH conditions of 5, 5.5, and 6. The presence of acetic acid in the fermentation media led to a significant decrease in the observed maximum cell biomass concentration. Glucose- and xylose-specific consumption rates decreased as the acetic acid concentration increased, with the inhibitory effect being more severe for xylose consumption. The ethanol production rates also decreased when acetic acid was present, but ethanol metabolic yields increased under the same conditions. The results also revealed that the inhibitory effect of acetic acid could be reduced by increasing media pH, thus confirming that the undissociated form of acetic acid is the inhibitory form of the molecule.

  10. ADSORPTION AND MEMBRANE SEPARATION MEASUREMENTS WITH MIXTURES OF ETHANOL, ACETIC ACID, AND WATER

    EPA Science Inventory

    Biomass fermentation produces ethanol and other renewable biofuels. Pervaporation using hydrophobic membranes is potentially a cost-effective means of removing biofuels from fermentation broths for small- to medium-scale applications. Silicalite-filled polydimethylsiloxane (PDMS)...

  11. The effect of flooding on the exchange of the volatile C2-compounds ethanol, acetaldehyde and acetic acid between leaves of Amazonian floodplain tree species and the atmosphere

    NASA Astrophysics Data System (ADS)

    Rottenberger, S.; Kleiss, B.; Kuhn, U.; Wolf, A.; Piedade, M. T. F.; Junk, W.; Kesselmeier, J.

    2008-02-01

    The effect of root inundation on the leaf emissions of ethanol, acetaldehyde and acetic acid was investigated with 2-3 years old tree seedlings of four Amazonian floodplain species by applying dynamic cuvette systems under greenhouse conditions. Emissions were monitored over a period of several days of inundation using a combination of Proton Transfer Reaction Mass Spectrometry (PTR-MS) and conventional techniques (HPLC, ion chromatography). Under non-flooded conditions, none of the species exhibited significant emissions of any of the compounds. A slight deposition of acetaldehyde and acetic acid was mainly observed, instead. Tree species specific variations in deposition velocities were largely due to variations in stomatal conductance. Flooding of the roots resulted in leaf emissions of ethanol and acetaldehyde by all species, while emissions of acetic acid occurred only by the species exhibiting the highest ethanol and acetaldehyde emission rates. All three compounds showed a similar diurnal emission profile, each displaying an emission burst in the morning, followed by a decline in the evening. This concurrent behavior supports the conclusion, that all three compounds emitted by the leaves are derived from ethanol produced in the roots by alcoholic fermentation, transported to the leaves with the transpiration stream and finally partly converted to acetaldehyde and acetic acid by enzymatic processes. Co-emissions and peaking in the early morning confirmed that root ethanol, after transportation with the transpiration stream to the leaves and enzymatic oxidation to acetaldehyde and acetate, is the metabolic precursor for all compounds emitted. Emission rates substantially varied among tree species, with maxima differing by up to two orders of magnitude (3-200 nmol m-2 min-1 for ethanol and 5-500 nmol m-2 min-1 for acetaldehyde). Acetic acid emissions reached 12 nmol m-2 min-1. The observed differences in emission rates between the tree species are discussed

  12. The effect of flooding on the exchange of the volatile C2-compounds ethanol, acetaldehyde and acetic acid between leaves of Amazonian floodplain tree species and the atmosphere

    NASA Astrophysics Data System (ADS)

    Rottenberger, S.; Kleiss, B.; Kuhn, U.; Wolf, A.; Piedade, M. T. F.; Junk, W.; Kesselmeier, J.

    2008-08-01

    The effect of root inundation on the leaf emissions of ethanol, acetaldehyde and acetic acid in relation to assimilation and transpiration was investigated with 2 3 years old tree seedlings of four Amazonian floodplain species by applying dynamic cuvette systems under greenhouse conditions. Emissions were monitored over a period of several days of inundation using a combination of Proton Transfer Reaction Mass Spectrometry (PTR-MS) and conventional techniques (HPLC, ion chromatography). Under non-flooded conditions, none of the species exhibited measurable emissions of any of the compounds, but rather low deposition of acetaldehyde and acetic acid was observed instead. Tree species specific variations in deposition velocities were largely due to variations in stomatal conductance. Flooding of the roots resulted in leaf emissions of ethanol and acetaldehyde by all species, while emissions of acetic acid were only observed from the species exhibiting the highest ethanol and acetaldehyde emission rates. All three compounds showed a similar diurnal emission profile, each displaying an emission burst in the morning, followed by a decline in the evening. This concurrent behavior supports the conclusion, that all three compounds emitted by the leaves are derived from ethanol produced in the roots by alcoholic fermentation, transported to the leaves with the transpiration stream and finally partly converted to acetaldehyde and acetic acid by enzymatic processes. Co-emissions and peaking in the early morning suggest that root ethanol, after transportation with the transpiration stream to the leaves and enzymatic oxidation to acetaldehyde and acetate, is the metabolic precursor for all compounds emitted, though we can not totally exclude other production pathways. Emission rates substantially varied among tree species, with maxima differing by up to two orders of magnitude (25 1700 nmol m-2 min-1 for ethanol and 5 500 nmol m-2 min-1 for acetaldehyde). Acetic acid emissions

  13. Improved ethanol production from xylose in the presence of acetic acid by the overexpression of the HAA1 gene in Saccharomyces cerevisiae.

    PubMed

    Sakihama, Yuri; Hasunuma, Tomohisa; Kondo, Akihiko

    2015-03-01

    The hydrolysis of lignocellulosic biomass liberates sugars, primarily glucose and xylose, which are subsequently converted to ethanol by microbial fermentation. The rapid and efficient fermentation of xylose by recombinant Saccharomyces cerevisiae strains is limited by weak acids generated during biomass pretreatment processes. In particular, acetic acid negatively affects cell growth, xylose fermentation rate, and ethanol production. The ability of S. cerevisiae to efficiently utilize xylose in the presence of acetic acid is an essential requirement for the cost-effective production of ethanol from lignocellulosic hydrolysates. Here, an acetic acid-responsive transcriptional activator, HAA1, was overexpressed in a recombinant xylose-fermenting S. cerevisiae strain to yield BY4741X/HAA1. This strain exhibited improved cell growth and ethanol production from xylose under aerobic and oxygen limited conditions, respectively, in the presence of acetic acid. The HAA1p regulon enhanced transcript levels in BY4741X/HAA1. The disruption of PHO13, a p-nitrophenylphosphatase gene, in BY4741X/HAA1 led to further improvement in both yeast growth and the ability to ferment xylose, indicating that HAA1 overexpression and PHO13 deletion act by different mechanisms to enhance ethanol production.

  14. Transport of acetic acid in Zygosaccharomyces bailii: effects of ethanol and their implications on the resistance of the yeast to acidic environments.

    PubMed Central

    Sousa, M J; Miranda, L; Côrte-Real, M; Leão, C

    1996-01-01

    Cells of Zygosaccharomyces bailii ISA 1307 grown in a medium with acetic acid, ethanol, or glycerol as the sole carbon and energy source transported acetic acid by a saturable transport system. This system accepted propionic and formic acids but not lactic, sorbic, and benzoic acids. When the carbon source was glucose or fructose, the cells displayed activity of a mediated transport system specific for acetic acid, apparently not being able to recognize other monocarboxylic acids. In both types of cells, ethanol inhibited the transport of labelled acetic acid. The inhibition was noncompetitive, and the dependence of the maximum transport rate on the ethanol concentration was found to be exponential. These results reinforced the belief that, under the referenced growth conditions, the acid entered the cells mainly through a transporter protein. The simple diffusion of the undissociated acid appeared to contribute, with a relatively low weight, to the overall acid uptake. It was concluded that in Z. bailii, ethanol plays a protective role against the possible negative effects of acetic acid by inhibiting its transport and accumulation. Thus, the intracellular concentration of the acid could be maintained at levels lower than those expected if the acid entered the cells only by simple diffusion. PMID:8795203

  15. Deuterium isotope effects on the ionization constant of acetic acid in H2O and D2O by AC conductance from 368 to 548 K at 20 MPa.

    PubMed

    Erickson, K M; Arcis, H; Raffa, D; Zimmerman, G H; Tremaine, P R

    2011-03-31

    Values of the ionization constant of acetic acid in H(2)O and D(2)O (K(HAc) and K(DAc)) and the deuterium isotope effect, ΔpK = pK(DAc) - pK(HAc), have been determined from T = 368 K to T = 548 K at p = 20 MPa, using a flow-through ac conductance cell built at the University of Delaware. Measurements were made on dilute (ionic strength ∼ 10(-4) mol·kg(-1)) solutions of acetic acid, sodium acetate, hydrochloric acid, and sodium chloride in H(2)O and D(2)O, injected in sequence at each temperature and pressure, so that systematic errors in the measured conductance of each solution would cancel. Experimental values for the molar conductivity, Λ, of the strong electrolytes were used to calculate the molar conductivity at infinite dilution, Λ°, using the Fuoss-Hsia-Fernández-Prini (FHFP) equation. These were used to calculate the molar conductivity at infinite dilution for acetic acid which was in turn used to calculate the degree of dissociation and finally the ionization constants of acetic acid. This same procedure was done for the pertinent deuterated solutes in D(2)O. Measured values of log K(HAc), log K(DAc), and ΔpK were obtained to a precision of ±0.008. The present results are in agreement with the only other accurate study at high temperatures and pressures (Mesmer, R. E.; Herting, D. L. J. Solution Chem.1978, 7, 901-913). The deuterium isotope effects, ΔpK, become independent of temperature above ∼420 K, at a value approximately 0.1 unit lower than that at 298 K. These values are ΔpK = 0.43 ± 0.01 and ΔpK = 0.51 ± 0.01, respectively. The temperature dependence of the Walden product ratio, (λ°η)(D(2)O)/(λ°η)(H(2)O), indicates a change in the relative hydration behavior of ions, whereby the effective Stokes radii of the sodium, chloride, and acetate ions in D(2)O relative to H(2)O reverse above ∼423 K. The results also suggest that the greater efficiency of the well-established proton-hopping transport mechanisms for OH(-) and H(3)O

  16. Hypoglycemic Effect of Ethanol and Ethyl Acetate Extract of Phellinus baumii Fruiting Body in Streptozotocin-Induced Diabetic Mice

    PubMed Central

    Wang, Wen-Han; Wu, Fei-Hua; Yang, Yan; Wu, Na; Zhang, Jing-Song; Feng, Na; Tang, Chuan-Hong

    2015-01-01

    We investigated hypoglycemic effect of ethanol (EtOH) and ethyl acetate extract acetate (AcOEt) extracts in streptozotocin- (STZ-) induced diabetic mice. Our data showed the maximum inhibitory effect on the fasting plasma glucose (FPG) level was detected in STZ-induced diabetic mice administered with 400 mg/kg AcOEt extract of P. baumii. A lower glycated albumin (GA) level and a higher insulin level were observed in 400 mg/kg AcOEt and EtOH extract groups. Moreover, 400 mg/kg AcOEt and EtOH extract exhibited a stronger effect on increasing size and cell number of islets. The insulin expression level of β-cells and integrated optical density (IOD) value were significantly increased by the administration of 400 mg/kg AcOEt and EtOH extracts. Taken together, AcOEt and EtOH extracts of P. baumii fruiting body exhibited considerable hypoglycemic effect on STZ-induced diabetic mice. PMID:26221177

  17. Improved growth and ethanol fermentation of Saccharomyces cerevisiae in the presence of acetic acid by overexpression of SET5 and PPR1.

    PubMed

    Zhang, Ming-Ming; Zhao, Xin-Qing; Cheng, Cheng; Bai, Feng-Wu

    2015-12-01

    To better understand the contribution of zinc-finger proteins to environmental stress tolerance, particularly inhibition from acetic acid, which is a potent inhibitor for cellulosic ethanol production by microbial fermentations, SET5 and PPR1 were overexpressed in Saccharomyces cerevisiae BY4741. With 5 g/L acetic acid addition, engineered strains BY4741/SET5 and BY4741/PPR1 showed improved growth and enhanced ethanol fermentation performance compared to that with the control strain. Similar results were also observed in ethanol production using corn stover hydrolysate. Further studies indicated that SET5 and PPR1 overexpression in S. cerevisiae significantly improved activities of antioxidant enzymes and ATP generation in the presence of acetic acid, and consequently decreased intracellular accumulation of reactive oxygen species (50.9 and 45.7%, respectively). These results revealed the novel functions of SET5 and PPR1 for the improvement of yeast acetic acid tolerance, and also implicated the involvement of these proteins in oxidative stress defense and energy metabolism in S. cerevisiae. This work also demonstrated that overexpression of SET5 and PPR1 would be a feasible strategy to increase cellulosic ethanol production efficiency.

  18. Effects of ethanol and acetic acid on the transport of malic acid and glucose in the yeast Schizosaccharomyces pombe: implications in wine deacidification.

    PubMed

    Sousa, M J; Mota, M; Leão, C

    1995-02-15

    Ethanol and acetic acid, at concentrations which may occur during wine-making, inhibited the transport of L-malic acid in Schizosaccharomyces pombe. The inhibition was non-competitive, the decrease of the maximum initial velocity following exponential kinetics. Glucose transport was not significantly affected either by ethanol (up to 13%, w/v) or by acetic acid (up to 1.5%, w/v). The uptake of labelled acetic acid followed simple diffusion kinetics, indicating that a carrier was not involved in its transport. Therefore, the undissociated acid appears to be the only form that enters the cells and is probably responsible for the toxic effects. Accordingly, deacidification by Ss. pombe during wine fermentation should take place before, rather than after, the main alcoholic fermentation by Saccharomyces cerevisiae.

  19. Anti-inflammatory drugs. IX. Hydrated diethylammonium (2-(2,6-dichlorophenylamino)phenyl)acetate (HDEA.D.H2O).

    PubMed

    Castellari, C; Comelli, F; Ottani, S

    2001-04-01

    In the solid-state structure of the title compound, C(4)H(12)N(+).C(14)H(10)Cl(2)NO(2)(-).H(2)O, the asymmetric unit contains one cation, one anion and a water molecule. A complex network of hydrogen bonds is present. A comparison is made with the structure of the anhydrous salt.

  20. Vapor-liquid equilibrium measurements at 101. 32 kPa for binary mixtures of methyl acetate + ethanol or 1-propanol

    SciTech Connect

    Ortega, J.: Susial, P.; de Alfonso, C. )

    1990-07-01

    This paper reports on isobaric vapor-liquid equilibrium data at 101.32 {plus minus} 0.02 kPa for methyl acetate (1) + ethane (2) or + 1-propanol (2). The results are compared with those predicted by the UNIFAC and ASOG methods. The methyl acetate (1) + ethanol (2) system forms an azeotrope at 329.8 K and a molar concentration of x{sub 1} = 0.958. Both methods predict the vapor-phase compositions equally well, with overall mean errors of less than 5%.

  1. Crystal structure of a mixed-ligand dinuclear Ba-Zn complex with 2-meth-oxy-ethanol having tri-phenyl-acetate and chloride bridges.

    PubMed

    Utko, Józef; Sobocińska, Maria; Dobrzyńska, Danuta; Lis, Tadeusz

    2015-07-01

    The dinuclear barium-zinc complex, μ-chlorido-1:2κ(2) Cl:Cl-chlorido-2κCl-bis-(2-meth-oxy-ethanol-1κO)bis-(2-meth-oxy-ethanol-1κ(2) O,O')bis-(μ-tri-phenyl-acetato-1:2κ(2) O:O')bariumzinc, [BaZn(C20H15O2)2Cl2(C3H8O2)4], has been synthesized by the reaction of barium tri-phenyl-acetate, anhydrous zinc chloride and 2-meth-oxy-ethanol in the presence of toluene. The barium and zinc metal cations in the dinuclear complex are linked via one chloride anion and carboxyl-ate O atoms of the tri-phenyl-acetate ligands, giving a Ba⋯Zn separation of 3.9335 (11) Å. The irregular nine-coordinate BaO8Cl coordination centres comprise eight O-atom donors, six of them from 2-meth-oxy-ethanol ligands (four from two bidentate O,O'-chelate inter-actions and two from monodentate inter-actions), two from bridging tri-phenyl-acetate ligands and one from a bridging Cl donor. The distorted tetra-hedral coordination sphere of zinc comprises two O-atom donors from the tri-phenyl-acetate ligands and two Cl donors (one bridging and one terminal). In the crystal, O-H⋯Cl, O-H⋯O and C-H⋯Cl inter-molecular inter-actions form a layered structure, lying parallel to (001).

  2. Effects of acetic acid, ethanol, and SO(2) on the removal of volatile acidity from acidic wines by two Saccharomyces cerevisiae commercial strains.

    PubMed

    Vilela-Moura, Alice; Schuller, Dorit; Mendes-Faia, Arlete; Côrte-Real, Manuela

    2010-07-01

    Herein, we report the influence of different combinations of initial concentration of acetic acid and ethanol on the removal of acetic acid from acidic wines by two commercial Saccharomyces cerevisiae strains S26 and S29. Both strains reduced the volatile acidity of an acidic wine (1.0 gl(-1) acetic acid and 11% (v/v) ethanol) by 78% and 48%, respectively. Acetic acid removal by strains S26 and S29 was associated with a decrease in ethanol concentration of 0.7 and 1.2% (v/v), respectively. Strain S26 revealed better removal efficiency due to its higher tolerance to stress factors imposed by acidic wines. Sulfur dioxide (SO(2)) in the concentration range 95-170 mg l(-1)inhibits the ability of both strains to reduce the volatile acidity of the acidic wine used under our experimental conditions. Therefore, deacidification should be carried out either in wines stabilized by filtration or in wines with SO(2)concentrations up to 70 mg l(-1). Deacidification of wines with the better performing strain S26 was associated with changes in the concentration of volatile compounds. The most pronounced increase was observed for isoamyl acetate (banana) and ethyl hexanoate (apple, pineapple), with an 18- and 25-fold increment, respectively, to values above the detection threshold. The acetaldehyde concentration of the deacidified wine was 2.3 times higher, and may have a detrimental effect on the wine aroma. Moreover, deacidification led to increased fatty acids concentration, but still within the range of values described for spontaneous fermentations, and with apparently no negative impact on the organoleptical properties.

  3. Vasa vasorum anti-angiogenesis through H2O2, HIF-1α, NF-κB, and iNOS inhibition by mangosteen pericarp ethanolic extract (Garcinia mangostana Linn) in hypercholesterol-diet-given Rattus norvegicus Wistar strain

    PubMed Central

    Wihastuti, Titin Andri; Sargowo, Djanggan; Tjokroprawiro, Askandar; Permatasari, Nur; Widodo, Mohammad Aris; Soeharto, Setyowati

    2014-01-01

    Background Oxidative stress in atherosclerosis produces H2O2 and triggers the activation of nuclear factor kappa beta (NF-κB) and increase of inducible nitric oxide synthase (iNOS). The formation of vasa vasorum occurs in atherosclerosis. Vasa vasorum angiogenesis is mediated by VEGFR-1 and upregulated by hypoxia-inducible factor-1α (HIF-1α). The newly formed vasa vasorum are fragile and immature and thus increase plaque instability. It is necessary to control vasa vasorum angiogenesis by using mangosteen pericarp antioxidant. This study aims to demonstrate that mangosteen pericarp ethanolic extract can act as vasa vasorum anti-angiogenesis through H2O2, HIF-1α, NF-κB, and iNOS inhibition in rats given a hypercholesterol diet. Methods This was a true experimental laboratory, in vivo posttest with control group design, with 20 Rattus norvegicus Wistar strain rats divided into five groups (normal group, hypercholesterol group, and hypercholesterol groups with certain doses of mangosteen pericarp ethanolic extract: 200, 400, and 800 mg/kg body weight). The parameters of this study were H2O2 measured by using colorimetric analysis, as well as NF-κB, iNOS, and HIF-1α, which were measured by using immunofluorescence double staining and observed with a confocal laser scanning microscope in aortic smooth muscle cell. The angiogenesis of vasa vasorum was quantified from VEGFR-1 level in aortic tissue and confirmed with hematoxylin and eosin staining. Results Analysis of variance test and Pearson’s correlation coefficient showed mangosteen pericarp ethanolic extract had a significant effect (P<0.05) in decreasing vasa vasorum angiogenesis through H2O2, HIF-1α, NF-κB, and iNOS inhibition in hypercholesterol-diet-given R. norvegicus Wistar strain. Conclusion Mangosteen pericarp ethanolic extract 800 mg/kg body weight is proven to decrease vasa vasorum angiogenesis. Similar studies with other inflammatory parameters are encouraged to clarify the mechanism of vasa

  4. Activation of apoptosis by ethyl acetate fraction of ethanol extract of Dianthus superbus in HepG2 cell line.

    PubMed

    Yu, Jian-Qing; Yin, Yan; Lei, Jia-Chuan; Zhang, Xiu-Qiao; Chen, Wei; Ding, Cheng-Li; Wu, Shan; He, Xiao-Yu; Liu, Yan-Wen; Zou, Guo-Lin

    2012-02-01

    Dianthus superbus L. is commonly used as a traditional Chinese medicine. We recently showed that ethyl acetate fraction (EE-DS) from ethanol extract of D. superbus exhibited the strongest antioxidant and cytotoxic activities. In this study, we examined apoptosis of HepG2 cells induced by EE-DS, and the mechanism underlying apoptosis was also investigated. Treatment of HepG2 cells with EE-DS (20-80 μg/ml) for 48 h led to a significant dose-dependent increase in the percentage of cells in sub-G1 phase by analysis of the content of DNA in cells, and a large number of apoptotic bodies containing nuclear fragments were observed in cells treated with 80 μg/ml of EE-DS for 24 h by using Hoechst 33258 staining. These data show that EE-DS can induce apoptosis of HepG2 cells. Immunoblot analysis showed that EE-DS significantly suppressed the expressions of Bcl-2 and NF-κB. Treatment of cells with EE-DS (80 μg/ml) for 48 h resulted in significant increase of cytochrome c in the cytosol, which indicated cytochrome c release from mitochondria. Activation of caspase-9 and -3 were also determined when the cells treated with EE-DS. The results suggest that apoptosis of HepG2 cells induced by EE-DS could be through the mitochondrial intrinsic pathway. High performance liquid chromatography (HPLC) data showed that the composition of EE-DS is complicated. Further studies are needed to find the effective constituents of EE-DS.

  5. Hydroethanolic extract of Baccharis trimera promotes gastroprotection and healing of acute and chronic gastric ulcers induced by ethanol and acetic acid.

    PubMed

    Dos Reis Lívero, Francislaine Aparecida; da Silva, Luisa Mota; Ferreira, Daniele Maria; Galuppo, Larissa Favaretto; Borato, Debora Gasparin; Prando, Thiago Bruno Lima; Lourenço, Emerson Luiz Botelho; Strapasson, Regiane Lauriano Batista; Stefanello, Maria Élida Alves; Werner, Maria Fernanda de Paula; Acco, Alexandra

    2016-09-01

    Ethanol is a psychoactive substance highly consumed around the world whose health problems include gastric lesions. Baccharis trimera is used in folk medicine for the treatment of gastrointestinal disorders. However, few studies have evaluated its biological and toxic effects. To validate the popular use of B. trimera and elucidate its possible antiulcerogenic and cytotoxic mechanisms, a hydroethanolic extract of B. trimera (HEBT) was evaluated in models of gastric lesions. Rats and mice were used to evaluate the protective and antiulcerogenic effects of HEBT on gastric lesions induced by ethanol, acetic acid, and chronic ethanol consumption. The effects of HEBT were also evaluated in a pylorus ligature model and on gastrointestinal motility. The LD50 of HEBT in mice was additionally estimated. HEBT was analyzed by nuclear magnetic resonance, and a high-performance liquid chromatography fingerprint analysis was performed. Oral HEBT administration significantly reduced the lesion area and the oxidative stress induced by acute and chronic ethanol consumption. However, HEBT did not protect against gastric wall mucus depletion and did not alter gastric secretory volume, pH, or total acidity in the pylorus ligature model. Histologically, HEBT accelerated the healing of chronic gastric ulcers in rats, reflected by contractions of the ulcer base. Flavonoids and caffeoylquinic acids were detected in HEBT, which likely contributed to the therapeutic efficacy of HEBT, preventing or reversing ethanol- and acetic acid-induced ulcers, respectively. HEBT antiulcerogenic activity may be partially attributable to the inhibition of free radical generation and subsequent prevention of lipid peroxidation. Our results indicate that HEBT has both gastroprotective and curative activity in animal models, with no toxicity.

  6. Models construction for acetone-butanol-ethanol fermentations with acetate/butyrate consecutively feeding by graph theory.

    PubMed

    Li, Zhigang; Shi, Zhongping; Li, Xin

    2014-05-01

    Several fermentations with consecutively feeding of acetate/butyrate were conducted in a 7 L fermentor and the results indicated that exogenous acetate/butyrate enhanced solvents productivities by 47.1% and 39.2% respectively, and changed butyrate/acetate ratios greatly. Then extracellular butyrate/acetate ratios were utilized for calculation of acids rates and the results revealed that acetate and butyrate formation pathways were almost blocked by corresponding acids feeding. In addition, models for acetate/butyrate feeding fermentations were constructed by graph theory based on calculation results and relevant reports. Solvents concentrations and butanol/acetone ratios of these fermentations were also calculated and the results of models calculation matched fermentation data accurately which demonstrated that models were constructed in a reasonable way.

  7. Development of an Alcohol Dehydrogenase Biosensor for Ethanol Determination with Toluidine Blue O Covalently Attached to a Cellulose Acetate Modified Electrode

    PubMed Central

    Alpat, Şenol; Telefoncu, Azmi

    2010-01-01

    In this work, a novel voltammetric ethanol biosensor was constructed using alcohol dehydrogenase (ADH). Firstly, alcohol dehydrogenase was immobilized on the surface of a glassy carbon electrode modified by cellulose acetate (CA) bonded to toluidine blue O (TBO). Secondly, the surface was covered by a glutaraldehyde/bovine serum albumin (BSA) cross-linking procedure to provide a new voltammetric sensor for the ethanol determination. In order to fabricate the biosensor, a new electrode matrix containing insoluble Toluidine Blue O (TBO) was obtained from the process, and enzyme/coenzyme was combined on the biosensor surface. The influence of various experimental conditions was examined for the characterization of the optimum analytical performance. The developed biosensor exhibited sensitive and selective determination of ethanol and showed a linear response between 1 × 10−5 M and 4 × 10−4 M ethanol. A detection limit calculated as three times the signal-to-noise ratio was 5.0 × 10−6 M. At the end of the 20th day, the biosensor still retained 50% of its initial activity. PMID:22315566

  8. Development of an alcohol dehydrogenase biosensor for ethanol determination with toluidine blue O covalently attached to a cellulose acetate modified electrode.

    PubMed

    Alpat, Senol; Telefoncu, Azmi

    2010-01-01

    In this work, a novel voltammetric ethanol biosensor was constructed using alcohol dehydrogenase (ADH). Firstly, alcohol dehydrogenase was immobilized on the surface of a glassy carbon electrode modified by cellulose acetate (CA) bonded to toluidine blue O (TBO). Secondly, the surface was covered by a glutaraldehyde/bovine serum albumin (BSA) cross-linking procedure to provide a new voltammetric sensor for the ethanol determination. In order to fabricate the biosensor, a new electrode matrix containing insoluble Toluidine Blue O (TBO) was obtained from the process, and enzyme/coenzyme was combined on the biosensor surface. The influence of various experimental conditions was examined for the characterization of the optimum analytical performance. The developed biosensor exhibited sensitive and selective determination of ethanol and showed a linear response between 1 × 10(-5) M and 4 × 10(-4) M ethanol. A detection limit calculated as three times the signal-to-noise ratio was 5.0 × 10(-6) M. At the end of the 20(th) day, the biosensor still retained 50% of its initial activity.

  9. Modification of the Farr assay using ethanol-ammonium acetate precipitation and its application to the measurement of affinity of anti-HCG produced in several species.

    PubMed

    Thanavala, Y M; Hay, F C

    1978-01-01

    A double isotope modified Farr assay was used to determine the total binding sites and affinity of antibodies to human chorionic gonadotrophin. Precipitation of the antigen--antibody complex at equilibrium with ammonium sulphate gave very high levels of nonspecific binding. Good discrimination over background was observed using a specific anti-immunoglobulin serum. However since we were interested in measuring the affinity of antibodies raised in several animal species it was more appropriate to use a single nonspecies precipitating reagent. We found that the use of a mixture of ethanol-ammonium acetate gave very low levels of non-specific binding in baboons, marmosets, rabbits and mice.

  10. Comparison of solid-state and submerged-state fermentation for the bioprocessing of switchgrass to ethanol and acetate by Clostridium phytofermentans.

    PubMed

    Jain, Abhiney; Morlok, Charles K; Henson, J Michael

    2013-01-01

    The conversion of sustainable energy crops using microbiological fermentation to biofuels and bioproducts typically uses submerged-state processes. Alternatively, solid-state fermentation processes have several advantages when compared to the typical submerged-state processes. This study compares the use of solid-state versus submerged-state fermentation using the mesophilic anaerobic bacterium Clostridium phytofermentans in the conversion of switchgrass to the end products of ethanol, acetate, and hydrogen. A shift in the ratio of metabolic products towards more acetate and hydrogen production than ethanol production was observed when C. phytofermentans was grown under solid-state conditions as compared to submerged-state conditions. Results indicated that the end product concentrations (in millimolar) obtained using solid-state fermentation were higher than using submerged-state fermentation. In contrast, the total fermentation products (in weight of product per weight of carbohydrates consumed) and switchgrass conversion were higher for submerged-state fermentation. The conversion of xylan was greater than glucan conversion under both fermentation conditions. An initial pH of 7 and moisture content of 80 % resulted in maximum end products formation. Scanning electron microscopy study showed the presence of biofilm formed by C. phytofermentans growing on switchgrass under submerged-state fermentation whereas bacterial cells attached to surface and no apparent biofilm was observed when grown under solid-state fermentation. To our knowledge, this is the first study reporting consolidated bioprocessing of a lignocellulosic substrate by a mesophilic anaerobic bacterium under solid-state fermentation conditions.

  11. [H 4tren] 3/2·(Al 6F 24)·3H 2O, the most condensed fluoride in the Al(OH) 3- tren-HF aq.-ethanol system

    NASA Astrophysics Data System (ADS)

    Adil, K.; Marrot, J.; Leblanc, M.; Maisonneuve, V.

    2007-06-01

    The most condensed crystalline fluoride that appears in the Al(OH) 3- tren-HF aq.-ethanol system at 190 °C is found to be [H 4tren] 3/2·(Al 6F 24)·3H 2O. The structure is monoclinic, P2 1/ c, with a = 21.939(1) Å, b = 6.7180(2) Å, c = 23.329(1) Å, β = 111.324(2)°. ∞(Al 6F 24) chains result from the connection of (Al 7F 30) 9- polyanions by opposite AlF 6 octahedra. Hydrogen bonds are established between the ∞(Al 6F 24) chains and ordered or disordered [H 4tren] 4+ cations and water molecules.

  12. STABILITY OF MFI ZEOLITE-FILLED PDMS MEMBRANES DURING PERVAPORATIVE ETHANOL RECOVERY FROM AQUEOUS MIXTURES CONTAINING ACETIC ACID

    EPA Science Inventory

    Pervaporation is potentially a cost-effective means of recovering biofuels, such as ethanol, from biomass fermentation broths for small- to medium-scale applications (~2 - 20 million liters per year). Hydrophobic zeolite-filled polydimethylsiloxane (PDMS) membranes have been sho...

  13. Production of H(2) from cellulose by rumen microorganisms: effects of inocula pre-treatment and enzymatic hydrolysis.

    PubMed

    Ratti, Regiane Priscila; Botta, Lívia Silva; Sakamoto, Isabel Kimiko; Silva, Edson Luiz; Varesche, Maria Bernadete Amâncio

    2014-03-01

    H2 production from cellulose, using rumen fluid as the inoculum, has been investigated in batch experiments. Methanogenic archaea were inhibited by acid pre-treatment, which also inhibited cellulolytic microorganisms, and in consequence, the conversion of cellulose to H2. Positive results were observed only with the addition of cellulase. H2 yields were 18.5 and 9.6 mmol H2 g cellulose(-1) for reactors with 2 and 4 g cellulose l(-1) and cellulase, respectively. H2 was primarily generated by the butyric acid pathway and this was followed by formation of acetic acid, ethanol and n-butanol. In reactors using 4 g cellulose l(-1) and cellulase, the accumulation of alcohols negatively affected the H2 yield, which changed the fermentation pathways to solventogenesis. PCR-DGGE analysis showed changes in the microbial communities. The phylogenetic affiliations of the bands of DGGE were 99 % similar to Clostridium sp.

  14. Characteristics of lipid extraction from Chlorella sp. cultivated in outdoor raceway ponds with mixture of ethyl acetate and ethanol for biodiesel production.

    PubMed

    Lu, Weidong; Wang, Zhongming; Yuan, Zhenhong

    2015-09-01

    In this work, neutral lipids (NLs) extraction capacity and selectivity of six solvents were firstly compared. In addition, an eco-friendly solvent combination of ethyl acetate and ethanol (EA/E) was proposed and tested for lipid extraction from Chlorella sp. cultivated in outdoor raceway ponds and effect of extraction variables on lipid yield were intensively studied. Results indicated that lipid extraction yield was increased with solvent to biomass ratio but did not vary significantly when the value exceeded 20:1. Lipid yield was found to be strongly dependent on extraction temperature and time. Finally, fatty acid profiles of lipid were determined and results indicated that the major components were octadecanoic acid, palmitic acid, linoleic acid and linolenic acid, demonstrating that the lipid extracted from the Chlorella sp. cultivated in outdoor raceway ponds by EA/E was suitable feedstock for biodiesel production.

  15. Application of Acetate Buffer in pH Adjustment of Mash and its Influence on Fuel Ethanol Fermentation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A 2M sodium acetate buffer at pH 4.2 was used to adjust pH of liquefied mashes in a simultaneous saccharification and fermentation (SSF) procedure. Although 5 mL of the buffer did not bring the pH values of the mashes (~100 mL) from a sorghum hybrid to 4.2, it kept the system stable (pH from 4.7 to ...

  16. H2 blockers

    MedlinePlus

    ... ulcer disease - H2 blockers; PUD - H2 blockers; Gastroesophageal reflux - H2 blockers ... blockers are used to: Relieve symptoms of acid reflux, or gastroesophageal reflux disease (GERD). This is a ...

  17. Expression of NAD+-dependent formate dehydrogenase in Enterobacter aerogenes and its involvement in anaerobic metabolism and H2 production.

    PubMed

    Lu, Yuan; Zhao, Hongxin; Zhang, Chong; Lai, Qiheng; Wu, Xi; Xing, Xin-Hui

    2009-10-01

    An expression system for NAD(+)-dependent formate dehydrogenase gene (fdh1), from Candida boidinii, was constructed and cloned into Enterobacter aerogenes IAM1183. With the fdh1 expression, the total H(2) yield was attributed to a decrease in activity of the lactate pathway and an increase of the formate pathway flux due to the NADH regeneration. Analysis of the redox state balance and ethanol-to-acetate ratio in the fdhl-expressed strain showed that increased reducing power arose from the reconstruction of NADH regeneration pathway from formate thereby contributing to the improved H(2) production.

  18. Ethanolic extract of roots from Arctium lappa L. accelerates the healing of acetic acid-induced gastric ulcer in rats: Involvement of the antioxidant system.

    PubMed

    da Silva, Luisa Mota; Allemand, Alexandra; Mendes, Daniel Augusto G B; Dos Santos, Ana Cristina; André, Eunice; de Souza, Lauro Mera; Cipriani, Thales Ricardo; Dartora, Nessana; Marques, Maria Consuelo Andrade; Baggio, Cristiane Hatsuko; Werner, Maria Fernanda

    2013-01-01

    We evaluate the curative efficacy of the ethanolic extract (EET) of roots from Arctium lappa (bardana) in healing of chronic gastric ulcers induced by 80% acetic acid in rats and additionally studies the possible mechanisms underlying this action. Oral administration of EET (1, 3, 10 and 30mg/kg) reduced the gastric lesion area in 29.2%, 41.4%, 59.3% and 38.5%, respectively, and at 10mg/kg promoted significant regeneration of the gastric mucosa, which was confirmed by proliferating cell nuclear antigen immunohistochemistry. EET (10mg/kg) treatment did not increase the gastric mucus content but restored the superoxide dismutase activity, prevented the reduction of glutathione levels, reduced lipid hydroperoxides levels, inhibited the myeloperoxidase activity and reduced the microvascular permeability. In addition, EET reduced the free radical generation and increased scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals in vitro. Furthermore, intraduodenal EET (10 and 30mg/kg) decreased volume and acidity of gastric secretion. Total phenolic compounds were high in EET (Folin-Ciocalteau assay) and the analysis by liquid chromatography-mass spectrometry revealed that the main compounds present in EET were a serie of hydroxycinnamoylquinic acid isomers. In conclusion, these data reveal that EET promotes regeneration of damaged gastric mucosa, probably through its antisecretory and antioxidative mechanisms.

  19. Changes in glucose fermentation pathways by an enriched bacterial culture in response to regulated dissolved H2 concentrations.

    PubMed

    Zheng, Hang; Zeng, Raymond J; Duke, Mikel C; O'Sullivan, Cathryn A; Clarke, William P

    2015-06-01

    It is well established that metabolic pathways in the fermentation of organic waste are primarily controlled by dissolved H2 concentrations, but there is no reported study that compares observed and predicted shifts in fermentation pathways induced by manipulating the dissolved H2 concentration. A perfusion system is presented that was developed to control dissolved H2 concentrations in the continuous fermentation of glucose by a culture highly enriched towards Thermoanaerobacterium thermosaccharolyticum (86 ± 9% relative abundance) from an originally diverse consortia in the leachate of a laboratory digester fed with municipal solid waste. Media from a 2.5 L CSTR was drawn through sintered steel membrane filters to retain biomass, allowing vigorous sparging in a separate chamber without cellular disruption. Through a combination of sparging and variations in glucose feeding rate from 0.8 to 0.2 g/L/d, a range of steady state fermentations were performed with dissolved H2 concentrations as low as an equivalent equilibrated H2 partial pressure of 3 kPa. Trends in product formation rates were simulated using a H2 regulation partitioning model. The model correctly predicted the direction of products redistribution in response to H2 concentration changes and the acetate and butyrate formation rates when H2 concentrations were less than 6 kPa. However, the model over-estimated acetate, ethanol and butanol productions at the expense of butyrate production at higher H2 concentrations. The H2 yield at the lowest dissolved H2 concentration was 2.67 ± 0.08 mol H2 /mol glucose, over 300% higher than the yield achieved in a CSTR operated without sparging.

  20. Formation of combustible hydrocarbons and H2 during photocatalytic decomposition of various organic compounds under aerated and deaerated conditions.

    PubMed

    Mozia, Sylwia; Kułagowska, Aleksandra; Morawski, Antoni W

    2014-11-26

    A possibility of photocatalytic production of useful aliphatic hydrocarbons and H2 from various organic compounds, including acetic acid, methanol, ethanol and glucose, over Fe-modified TiO2 is discussed. In particular, the influence of the reaction atmosphere (N2, air) was investigated. Different gases were identified in the headspace volume of the reactor depending on the substrate. In general, the evolution of the gases was more effective in air compared to a N2 atmosphere. In the presence of air, the gaseous phase contained CO2, CH4 and H2, regardless of the substrate used. Moreover, formation of C2H6 and C3H8 in the case of acetic acid and C2H6 in the case of ethanol was observed. In case of acetic acid and methanol an increase in H2 evolution under aerated conditions was observed. It was concluded that the photocatalytic decomposition of organic compounds with simultaneous generation of combustible hydrocarbons and hydrogen could be a promising method of "green energy" production.

  1. Randomised controlled trial comparing percutaneous radiofrequency thermal ablation, percutaneous ethanol injection, and percutaneous acetic acid injection to treat hepatocellular carcinoma of 3 cm or less

    PubMed Central

    Lin, S-M; Lin, C-J; Lin, C-C; Hsu, C-W; Chen, Y-C

    2005-01-01

    Aims: The aim of this study was to compare the outcomes of radiofrequency thermal ablation (RFTA), percutaneous ethanol injection (PEI), and percutaneous acetic acid injection (PAI) in the treatment of hepatocellular carcinoma (HCC). Patients and methods: A total of 187 patients with HCCs of 3 cm or less were randomly assigned to RFTA (n = 62), PEI (n = 62), or PAI (n = 63). Tumour recurrence and survival rates were assessed. Results: One, two, and three year local recurrence rates were 10%, 14%, and 14% in the RFTA group, 16%, 34%, and 34% in the PEI group, and 14%, 31%, and 31% in the PAI group (RFTA v PEI, p = 0.012; RFTA v PAI, p = 0.017). One, two, and three year survival rates were 93%, 81%, and 74% in the RFTA group, 88%, 66%, and 51% in the PEI group, and 90%, 67%, and 53% in the PAI group (RFTA v PEI, p = 0.031; RFTA v PAI, p = 0.038). One, two, and three year cancer free survival rates were 74%, 60%, and 43% in the RFTA group, 70%, 41%, and 21% in the PEI group, and 71%, 43%, and 23% in the PAI group (RFTA v PEI, p = 0.038; RFTA v PAI, p = 0.041). Tumour size, tumour differentiation, and treatment methods (RFTA v PEI and PAI) were significant factors for local recurrence, overall survival, and cancer free survival. Major complications occurred in 4.8% of patients (two with haemothorax, one gastric perforation) in the RFTA group and in none in two other groups (RFTA v PEI and PAI, p = 0.035). Conclusions: RFTA was superior to PEI and PAI with respect to local recurrence, overall survival, and cancer free survival rates, but RFTA also caused more major complications. PMID:16009687

  2. Thermodynamics of Microbial Growth Coupled to Metabolism of Glucose, Ethanol, Short-Chain Organic Acids, and Hydrogen ▿ †

    PubMed Central

    Roden, Eric E.; Jin, Qusheng

    2011-01-01

    A literature compilation demonstrated a linear relationship between microbial growth yield and the free energy of aerobic and anaerobic (respiratory and/or fermentative) metabolism of glucose, ethanol, formate, acetate, lactate, propionate, butyrate, and H2. This relationship provides a means to estimate growth yields for modeling microbial redox metabolism in soil and sedimentary environments. PMID:21216913

  3. Stratospheric H2O

    NASA Technical Reports Server (NTRS)

    Ellsaesser, H. W.; Harries, J. E.; Kley, D.; Penndorf, R.

    1980-01-01

    The present state of our knowledge and understanding of H2O in the stratosphere is reviewed. This reveals continuing discrepancies between observations and expectations following from the Brewer-Dobson hypothesis of stratospheric circulation. In particular, available observations indicate unexplained upward and poleward directed H2O gradients immediately downstream from the tropical tropopause and variable vertical gradients above 20 km which generally disagree with those expected from oxidation of CH4.

  4. Treatment of an industrial stream containing vinylcyclohexene by the H2O2/UV process.

    PubMed

    Gonçalves, Lenise V F; Azevedo, Eduardo B; de Aquino-Neto, Francisco R; Bila, Daniele M; Sant'Anna, Geraldo L; Dezotti, Márcia

    2016-10-01

    Petrochemical industries generate wastewaters containing pollutants that can severely impact the biological treatment systems. Some streams from specific production units may contain nonbiodegradable or toxic compounds that impair the performance of the wastewater treatment plant and should be segregated and treated by specific techniques. In this work, the utilization of chemical oxidation (H2O2/UV) was investigated for removing 4-vinylcyclohexene (VCH) from a liquid stream coming from the production of hydroxylated liquid polybutadiene (HLPB). Besides VCH, this stream also contains ethanol, hydrogen peroxide, and many other organic compounds. Experiments were carried out in a small-scale photochemical reactor (0.7 L) using a 25-W low-pressure mercury vapor lamp. The photochemical reactor was operated in batch, and the reaction times were comprised between 10 and 60 min. Assays were also performed with a synthetic medium containing VCH, H2O2, and ethanol to investigate the removal of these substances in a less complex aqueous matrix. By-products formed in the reaction were identified by gas chromatography and mass spectroscopy (GC-MS). VCH was significantly removed by the oxidation process, in most assays to undetectable levels. Ethanol removal varied from 16 to 23 % depending on the reaction conditions. Acetic acid, acetaldehyde, and diols were detected as by-products of the industrial wastewater stream oxidation. A drop on the toxicity of the industrial stream was also observed in assays using the organism Artemia salina.

  5. Fermentation method producing ethanol

    DOEpatents

    Wang, Daniel I. C.; Dalal, Rajen

    1986-01-01

    Ethanol is the major end product of an anaerobic, thermophilic fermentation process using a mutant strain of bacterium Clostridium thermosaccharolyticum. This organism is capable of converting hexose and pentose carbohydrates to ethanol, acetic and lactic acids. Mutants of Clostridium thermosaccharolyticum are capable of converting these substrates to ethanol in exceptionally high yield and with increased productivity. Both the mutant organism and the technique for its isolation are provided.

  6. MELCOR-H2

    SciTech Connect

    2009-11-10

    Before this LDRD research, no single tool could simulate a very high temperature reactor (VHTR) that is coupled to a secondary system and the sulfur iodine (SI) thermochemistry. Furthermore, the SI chemistry could only be modeled in steady state, typically via flow sheets. Additionally, the MELCOR nuclear reactor analysis code was suitable only for the modeling of light water reactors, not gas-cooled reactors. We extended MELCOR in order to address the above deficiencies. In particular, we developed three VHTR input models, added generalized, modular secondary system components, developed reactor point kinetics, included transient thermochemistry for the most important cycles [SI and the Westinghouse hybrid sulfur], and developed an interactive graphical user interface for full plant visualization. The new tool is called MELCOR-H2, and it allows users to maximize hydrogen and electrical production, as well as enhance overall plant safety. We conducted validation and verification studies on the key models, and showed that the MELCOR-H2 results typically compared to within less than 5% from experimental data, code-to-code comparisons, and/or analytical solutions.

  7. Photocatalytic direct conversion of ethanol to 1,1- diethoxyethane over noble-metal-loaded TiO2 nanotubes and nanorods.

    PubMed

    Zhang, Hongxia; Wu, Yupeng; Li, Li; Zhu, Zhenping

    2015-04-13

    As one of the most important biomass platform molecules, ethanol needs to have its product chain chemically extended to meet future demands in renewable fuels and chemicals. Additionally, chemical conversion of ethanol under mild and green conditions is still a major challenge. In this work, ethanol is directly converted into 1,1-diethoxyethane (DEE) and H2 under mild photocatalytic conditions over platinum-loaded TiO2 nanotubes and nanorods. The reaction follows a tandem dehydrogenation-acetalization mechanism, in which ethanol is first dehydrogenated into acetaldehyde and H(+) ion by photogenerated holes, and then acetalization between acetaldehyde and ethanol proceeds through promotion by H(+) ions formed in real time. Excess H(+) ions are simultaneously reduced into H2 by photogenerated electrons. This photocatalytic process has a very high reaction rate over nanosized tubular and rod-like TiO2 photocatalysts, reaching 157.7 mmol g(-1)  h(-1) in relatively low photocatalyst feeding. More importantly, the reaction is highly selective, with a nearly stoichiometric conversion of reacted ethanol into DEE. This photocatalytic dehydrogenation CO coupling of ethanol is a new green approach to the direct efficient conversion of ethanol into DEE and provides a promising channel for sustainable bioethanol applications.

  8. Genome shuffling in the ethanologenic yeast Candida krusei to improve acetic acid tolerance.

    PubMed

    Wei, Pingying; Li, Zilong; He, Peng; Lin, Yuping; Jiang, Ning

    2008-02-01

    Genome shuffling was used to improve the acetic acid tolerance of an ethanologenic yeast, Candida krusei GL560. A mutant, S4-3, was isolated and selected after four rounds of genome shuffling. It was found that the mutant S4-3 had a higher viability in the YNBX (yeast nitrogen base/xylose) medium with acetic acid and grew better in the YPD (yeast extract, peptone and dextrose) medium [1% (w/v) yeast extract, 2% (w/v) peptone and 2% (w/v) glucose] with acetic acid than the parent strain GL560. The mutant S4-3 also improved its multiple stress tolerance to ethanol, H2O2, heat and freeze-thaw. Furthermore, S4-3 showed higher ethanol production than GL560 in EFM (ethanol fermentation medium) with or without acetic acid. The DNA content of S4-3 was similar to its parent strains in the genome shuffling. This suggested that gene exchange, as caused by homologous recombination, may have occurred during the process. Higher membrane integrity and intracellular catalase activity were two possible reasons for the higher acid-tolerance phenotype of S4-3. These results indicated that genome shuffling is a powerful means of rapidly improving the complex traits of non-haploid organisms, while still maintaining robust growth.

  9. [Synthesis and spectra of transition metals complexes RE3L6(NO3)6(H2O)2].

    PubMed

    Zhao, Qing-shan; Mao, Ju-lin; Zhou, Hui-liang; Hu, Qi-lin; Liu, Wan-yi

    2009-09-01

    Schiff base 4-(p-dimethylaminobenzaldehydeamino)-4H-1,2,4-triazole(L) was synthesized from 4-amino-1,2,4-triazole and p-dimethylaminobenzaldehyde using acetic acid as the catalyst. The solid complexes RE3L6(NO3)6(H2O)2 (RE = Cu, Co, Zn, Cd; x = 3-6) were synthesized with 4-(p-dimethylaminobenzaldehydeamino)-4H-1,2,4-triazole and nitrate of transition metals in ethanol and characterized by elemental analysis, infrared spectroscopy, UV spectrum, and fluorescence spectrum. Experimental results showed that the free ligand is a thermally stable material, and its ethanol solution emitted intense blue fluorescence at the peak wavelength of 416 nm. The absorption band at about 406 nm can be assigned to the intrinsic absorption of C==N. Compared with the fluorescence emission of free ligand in ethanol solution, the emission of the complex of RE3L6 (NO3)6(H2O)2 was red-shifted to 445 nm and narrow in solution. RE(II) was coordinated with N atomy of triazole in 4-(p-dimethylaminobenzaldehydeamino)-4H-1,2,4-triazole.

  10. Hydrogenoanaerobacterium saccharovorans gen. nov., sp. nov., isolated from H2-producing UASB granules.

    PubMed

    Song, Lei; Dong, Xiuzhu

    2009-02-01

    Two strictly anaerobic bacterial strains, designated SW512(T) and W72, were isolated from a laboratory-scale H(2)-producing up-flow anaerobic sludge blanket (UASB) reactor. Cells were Gram-stain-negative, non-motile and 0.3-0.4x2.0-14.5 mum; they did not form spores. Both strains grew at 24-45 degrees C (no growth at or=46 degrees C), with optimum growth at 37 degrees C. The pH range for growth was 4.5-9.0 (no growth at pHor=9.3), with optimum growth at pH 6.5-7.0. Several kinds of mono-, di- and oligosaccharides supported growth. The main end products of glucose fermentation were ethanol, acetate, hydrogen and carbon dioxide (according to the equation 1 mol glucose-->1.1 mol acetate+0.6 mol ethanol+2.6 mol H(2)+1.6 mol CO(2)). The DNA G+C contents of strains SW512(T) and W72 were 41.9+/-0.5 and 42.8+/-0.4 mol% (T(m) method), respectively. Phylogenetic analysis based on 16S rRNA gene sequence similarities indicated that the two strains represent a new phyletic sublineage within the family 'Ruminococcaceae', with <91.3 % 16S rRNA gene sequence similarity to recognized species. On the basis of the polyphasic evidence in this study, it is proposed that the two strains represent a novel species in a new genus, for which the name Hydrogenoanaerobacterium saccharovorans gen. nov., sp. nov. is proposed; the type strain of the type species is SW512(T) (=AS 1.5070(T)=JCM 14861(T)).

  11. Microbial physiology-based model of ethanol metabolism in subsurface sediments

    NASA Astrophysics Data System (ADS)

    Jin, Qusheng; Roden, Eric E.

    2011-07-01

    A biogeochemical reaction model was developed based on microbial physiology to simulate ethanol metabolism and its influence on the chemistry of anoxic subsurface environments. The model accounts for potential microbial metabolisms that degrade ethanol, including those that oxidize ethanol directly or syntrophically by reducing different electron acceptors. Out of the potential metabolisms, those that are active in the environment can be inferred by fitting the model to experimental observations. This approach was applied to a batch sediment slurry experiment that examined ethanol metabolism in uranium-contaminated aquifer sediments from Area 2 at the U.S. Department of Energy Field Research Center in Oak Ridge, TN. According to the simulation results, complete ethanol oxidation by denitrification, incomplete ethanol oxidation by ferric iron reduction, ethanol fermentation to acetate and H 2, hydrogenotrophic sulfate reduction, and acetoclastic methanogenesis: all contributed significantly to the degradation of ethanol in the aquifer sediments. The assemblage of the active metabolisms provides a frame work to explore how ethanol amendment impacts the chemistry of the environment, including the occurrence and levels of uranium. The results can also be applied to explore how diverse microbial metabolisms impact the progress and efficacy of bioremediation strategies.

  12. Production of hydrogen, ethanol and volatile fatty acids from the seaweed carbohydrate mannitol.

    PubMed

    Xia, Ao; Jacob, Amita; Herrmann, Christiane; Tabassum, Muhammad Rizwan; Murphy, Jerry D

    2015-10-01

    Fermentative hydrogen from seaweed is a potential biofuel of the future. Mannitol, which is a typical carbohydrate component of seaweed, was used as a substrate for hydrogen fermentation. The theoretical specific hydrogen yield (SHY) of mannitol was calculated as 5 mol H2/mol mannitol (615.4 mL H2/g mannitol) for acetic acid pathway, 3 mol H2/mol mannitol (369.2 mL H2/g mannitol) for butyric acid pathway and 1 mol H2/mol mannitol (123.1 mL H2/g mannitol) for lactic acid and ethanol pathways. An optimal SHY of 1.82 mol H2/mol mannitol (224.2 mL H2/g mannitol) was obtained by heat pre-treated anaerobic digestion sludge under an initial pH of 8.0, NH4Cl concentration of 25 mM, NaCl concentration of 50mM and mannitol concentration of 10 g/L. The overall energy conversion efficiency achieved was 96.1%. The energy was contained in the end products, hydrogen (17.2%), butyric acid (38.3%) and ethanol (34.2%).

  13. Filling Knowledge Gaps in Biological Networks: integrating global approaches to understand H2 metabolism in Chlamydomonas reinhardtii - Final Report

    SciTech Connect

    Posewitz, Matthew C

    2011-06-30

    The green alga Chlamydomonas reinhardtii (Chlamydomonas) has numerous genes encoding enzymes that function in fermentative pathways. Among these genes, are the [FeFe]-hydrogenases, pyruvate formate lyase, pyruvate ferredoxin oxidoreductase, acetate kinase, and phosphotransacetylase. We have systematically undertaken a series of targeted mutagenesis approaches to disrupt each of these key genes and omics techniques to characterize alterations in metabolic flux. Funds from DE-FG02-07ER64423 were specifically leveraged to generate mutants with disruptions in the genes encoding the [FeFe]-hydrogenases HYDA1 and HYDA2, pyruvate formate lyase (PFL1), and in bifunctional alcohol/aldehyde alcohol dehydrogenase (ADH1). Additionally funds were used to conduct global transcript profiling experiments of wildtype Chlamydomonas cells, as well as of the hydEF-1 mutant, which is unable to make H2 due to a lesion in the [FeFe]-hydrogenase biosynthetic pathway. In the wildtype cells, formate, acetate and ethanol are the dominant fermentation products with traces of CO2 and H2 also being produced. In the hydEF-1 mutant, succinate production is increased to offset the loss of protons as a terminal electron acceptor. In the pfl-1 mutant, lactate offsets the loss of formate production, and in the adh1-1 mutant glycerol is made instead of ethanol. To further probe the system, we generated a double mutant (pfl1-1 adh1) that is unable to synthesize both formate and ethanol. This strain, like the pfl1 mutants, secreted lactate, but also exhibited a significant increase in the levels of extracellular glycerol, acetate, and intracellular reduced sugars, and a decline in dark, fermentative H2 production. Whereas wild-type Chlamydomonas fermentation primarily produces formate and ethanol, the double mutant performs a complete rerouting of the glycolytic carbon to lactate and glycerol. Lastly, transcriptome data have been analysed for both the wildtype and hydEF-1, that correlate with our

  14. Enhancing acetone biosynthesis and acetone-butanol-ethanol fermentation performance by co-culturing Clostridium acetobutylicum/Saccharomyces cerevisiae integrated with exogenous acetate addition.

    PubMed

    Luo, Hongzhen; Ge, Laibing; Zhang, Jingshu; Ding, Jian; Chen, Rui; Shi, Zhongping

    2016-01-01

    Acetone is the major by-product in ABE fermentations, most researches focused on increasing butanol/acetone ratio by decreasing acetone biosynthesis. However, economics of ABE fermentation industry strongly relies on evaluating acetone as a valuable platform chemical. Therefore, a novel ABE fermentation strategy focusing on bio-acetone production by co-culturing Clostridium acetobutylicum/Saccharomyces cerevisiae with exogenous acetate addition was proposed. Experimental and theoretical analysis revealed the strategy could, enhance C. acetobutylicum survival oriented amino acids assimilation in the cells; control NADH regeneration rate at moderately lower level to enhance acetone synthesis but without sacrificing butanol production; enhance the utilization ability of C. acetobutylicum on glucose and direct most of extra consumed glucose into acetone/butanol synthesis routes. By implementing the strategy using synthetic or acetate fermentative supernatant, acetone concentrations increased to 8.27-8.55g/L from 5.86g/L of the control, while butanol concentrations also elevated to the higher levels of 13.91-14.23g/L from 11.63g/L simultaneously.

  15. Flecainide acetate acetic acid solvates.

    PubMed

    Veldre, Kaspars; Actiņs, Andris; Eglite, Zane

    2011-02-01

    Flecainide acetate forms acetic acid solvates with 0.5 and 2 acetic acid molecules. Powder X-ray diffraction, differential thermal analysis/thermogravimetric, infrared, and potentiometric titration were used to determine the composition of solvates. Flecainide acetate hemisolvate with acetic acid decomposes to form a new crystalline form of flecainide acetate. This form is less stable than the already known polymorphic form at all temperatures, and it is formed due to kinetic reasons. Both flecainide acetate nonsolvated and flecainide acetate hemisolvate forms crystallize in monoclinic crystals, but flecainide triacetate forms triclinic crystals. Solvate formation was not observed when flecainide base was treated with formic acid, propanoic acid, and butanoic acid. Only nonsolvated flecainide salts were obtained in these experiments.

  16. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium acetate. 184.1721 Section 184.1721 Food and....1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3 or C2H3O2Na·3H2O, CAS Reg. No. 6131-90-4) is the sodium salt of acetic acid and occurs naturally in plant and animal tissues....

  17. H2 Detection via Polarography

    NASA Technical Reports Server (NTRS)

    Dominquez, Jesus; Barile, Ron

    2006-01-01

    Polarography is the measurement of the current that flows in solution as a function of an applied voltage. The actual form of the observed polarographic current depends upon the manner in which the voltage is applied and on the characteristics of the working electrode. The new gas polarographic H2 sensor shows a current level increment with concentration of the gaseous H2 similar to those relating to metal ions in liquid electrolytes in well-known polarography. This phenomenon is caused by the fact that the diffusion of the gaseous H2 through a gas diffusion hole built in the sensor is a rate-determining step in the gaseous-hydrogen sensing mechanism. The diffusion hole artificially limits the diffusion of the gaseous H2 toward the electrode located at the sensor cavity. This gas polarographic H2 sensor is actually an electrochemical-pumping cell since the gaseous H2 is in fact pumped via the electrochemical driving force generated between the electrodes. Gaseous H2 enters the diffusion hole and reaches the first electrode (anode) located in the sensor cavity to be transformed into an H ions or protons; H ions pass through the electrolyte and reach the second electrode (cathode) to be reformed to gaseous H2. Gas polarographic O2 sensors are commercially available; a gas polarographic O2 sensor was used to prove the feasibility of building a new gas polarographic H2 sensor.

  18. Antiproton stopping in H2 and H2O

    NASA Astrophysics Data System (ADS)

    Bailey, J. J.; Kadyrov, A. S.; Abdurakhmanov, I. B.; Fursa, D. V.; Bray, I.

    2015-11-01

    Stopping powers of antiprotons in H2 and H2O targets are calculated using a semiclassical time-dependent convergent close-coupling method. In our approach the H2 target is treated using a two-center molecular multiconfiguration approximation, which fully accounts for the electron-electron correlation. Double-ionization and dissociative ionization channels are taken into account using an independent-event model. The vibrational excitation and nuclear scattering contributions are also included. The H2O target is treated using a neonization method proposed by C. C. Montanari and J. E. Miraglia [J. Phys. B 47, 015201 (2014), 10.1088/0953-4075/47/1/015201], whereby the ten-electron water molecule is described as a dressed Ne-like atom in a pseudospherical potential. Despite being the most comprehensive approach to date, the results obtained for H2 only qualitatively agree with the available experimental measurements.

  19. Mesoxalaldehyde acetals

    SciTech Connect

    Gordeeva, G.N.; Kalashnikov, S.M.; Popov, Yu.N.; Kruglov, E.A.; Imashev, U.B.

    1987-11-10

    The treatment of methylglyoxal acetals by alkyl nitrites in the presence of the corresponding aliphatic alcohols and hydrochloric acid leads to the formation of linear mesoxalaldehyde acetals, whose structure was established by NMR spectroscopy and mass spectrometry. The major pathways for the decomposition of these molecules upon electron impact were established.

  20. Ethyl acetate fraction of adlay bran ethanolic extract inhibits oncogene expression and suppresses DMH-induced preneoplastic lesions of the colon in F344 rats through an anti-inflammatory pathway.

    PubMed

    Chung, Cheng-Pei; Hsu, Hsin-Yi; Huang, Din-Wen; Hsu, Hsing-Hua; Lin, Ju-Tsui; Shih, Chun-Kuang; Chiang, Wenchang

    2010-07-14

    Adlay ( Coix lachryma-jobi L. var. ma-yuen Stapf) is a grass crop and was reported to possess anti-inflammatory activity and an antiproliferative effect in cancer cell lines. The purpose of this study was to evaluate the effects of the ethyl acetate fraction of an adlay bran ethanolic extract (ABE-Ea) on colon carcinogenesis in an animal model and investigate its mechanism. Male F344 rats received 1,2-dimethylhydrazine (DMH) and consumed different doses of ABE-Ea. The medium-dose group (17.28 mg of ABE-Ea/day) exhibited the best suppressive effect on colon carcinogenesis and prevented preneoplastic mucin-depleted foci (MDF) formation. Moreover, RAS and Ets2 oncogenes were significantly down-regulated in this group compared to the negative control group, whereas Wee1, a gene involved in the cell cycle, was up-regulated. Cyclooxygenase-2 (COX-2) protein expression was significantly suppressed in all colons receiving the ABE-Ea, indicating that ABE-Ea delayed carcinogenesis by suppressing chronic inflammation. ABE-Ea included considerable a proportion of phenolic compounds, and ferulic acid was the major phenolic acid (5206 microg/g ABE-Ea) on the basis of HPLC analysis. Results from this study suggest that ABE-Ea suppressed DMH-indued preneoplastic lesions of the colon in F344 rats and that ferulic acid may be one of the active compounds.

  1. Biogeochemistry of dihydrogen (H2).

    PubMed

    Hoehler, Tori M

    2005-01-01

    Hydrogen has had an important and evolving role in Earth's geo- and biogeochemistry, from prebiotic to modern times. On the earliest Earth, abiotic sources of H2 were likely stronger than in the present. Volcanic out-gassing and hydrothermal circulation probably occurred at several times the modern rate, due to presumably higher heat flux. The H2 component of volcanic emissions was likely buffered close to the modern value by an approximately constant mantle oxidation state since 3.9 billion years ago, and may have been higher before that, if the early mantle was more reducing. The predominantly ultramafic character of the early, undifferentiated crust could have led to increased serpentinization and release of H2 by hydrothermal circulation, as in modern ultramafic-hosted vents. At the same time, the reactive atmospheric sink for H2 was likely weaker. Collectively, these factors suggest that steady state levels of H2 in the prebiotic atmosphere were 3-4 orders of magnitude higher than at present, and possibly higher still during transient periods following the delivery of Fe and Ni by large impact events. These elevated levels had direct or indirect impacts on the redox state of the atmosphere, the radiation budget, the production of aerosol hazes, and the genesis of biochemical precursor compounds. The early abiotic cycling of H2 helped to establish the environmental and chemical context for the origins of life on Earth. The potential for H2 to serve as a source of energy and reducing power, and to afford a means of energy storage by the establishment of proton gradients, could have afforded it a highly utilitarian role in the earliest metabolic chemistry. Some origin of life theories suggest the involvement of H2 in the first energy-generating metabolism, and the widespread and deeply-branching nature of H2-utilization in the modern tree of life suggests that it was at least a very early biochemical innovation. The abiotic production of H2 via several mechanisms

  2. Kinetics of Ethyl Acetate Synthesis Catalyzed by Acidic Resins

    ERIC Educational Resources Information Center

    Antunes, Bruno M.; Cardoso, Simao P.; Silva, Carlos M.; Portugal, Ines

    2011-01-01

    A low-cost experiment to carry out the second-order reversible reaction of acetic acid esterification with ethanol to produce ethyl acetate is presented to illustrate concepts of kinetics and reactor modeling. The reaction is performed in a batch reactor, and the acetic acid concentration is measured by acid-base titration versus time. The…

  3. Electrochemical and biochemical analysis of ethanol fermentation of zymomonas mobilis KCCM11336.

    PubMed

    Jeon, Bo Young; Hwang, Tae Sik; Park, Doo Hyun

    2009-07-01

    An electrochemical bioreactor (ECB) composed of a cathode compartment and an air anode was used in this study to characterize the ethanol fermentation of Zymomonas mobilis. The cathode and air anode were constructed of modified graphite felt with neutral red (NR) and a modified porous carbon plate with cellulose acetate and porous ceramic membrane, respectively. The air anode operates as a catalyst to generate protons and electrons from water. The growth and ethanol production of Z. mobilis were 50% higher in the ECB than were observed under anoxic nitrogen conditions. Ethanol production by growing cells and the crude enzyme of Z. mobilis were significantly lower under aerobic conditions than under other conditions. The growing cells and crude enzyme of Z. mobilis did not catalyze ethanol production from pyruvate and acetaldehyde. The membrane fraction of crude enzyme catalyzed ethanol production from glucose, but the soluble fraction did not. NADH was oxidized to NAD+ in association with H2O2 reduction, via the catalysis of crude enzyme. Our results suggested that NADH/NAD+ balance may be a critical factor for ethanol producton from glucose in the metabolism of Z. mobilis, and that the metabolic activity of both growing cells and crude enzyme for ethanol fermentation may be induced in the presence of glucose.

  4. An electron-flow model can predict complex redox reactions in mixed-culture fermentative bioH2: microbial ecology evidence.

    PubMed

    Lee, Hyung-Sool; Krajmalinik-Brown, Rosa; Zhang, Husen; Rittmann, Bruce E

    2009-11-01

    We developed the first model for predicting community structure in mixed-culture fermentative biohydrogen production using electron flows and NADH2 balances. A key assumption of the model is that H2 is produced only via the pyruvate decarboxylation-ferredoxin-hydrogenase pathway, which is commonly the case for fermentation by Clostridium and Ethanoligenens species. We experimentally tested the model using clone libraries to gauge community structures with mixed cultures in which we did not pre-select for specific bacterial groups, such as spore-formers. For experiments having final pHs 3.5 and 4.0, where H2 yield and soluble end-product distribution were distinctly different, we established stoichiometric reactions for each condition by using experimentally determined electron equivalent balances. The error in electron balancing was only 3% at final pH 3.5, in which butyrate and acetate were dominant organic products and the H2 yield was 2.1 mol H2/mol glucose. Clone-library analysis showed that clones affiliated with Clostridium sp. BL-22 and Clostridium sp. HPB-16 were dominant at final pH 3.5. For final pH 4.0, the H2 yield was 0.9 mol H2/mol glucose, ethanol, and acetate were the dominant organic products, and the electron balance error was 13%. The significant error indicates that a second pathway for H2 generation was active. The most abundant clones were affiliated with Klebsiella pneumoniae, which uses the formate-cleavage pathway for H2 production. Thus, the clone-library analyses confirmed that the model predictions for when the pyruvate decarboxylation-ferredoxin-hydrogenase pathway was (final pH 3.5) or was not (final pH 4.0) dominant. With the electron-flow model, we can easily assess the main mechanisms for H2 formation and the dominant H2-producing bacteria in mixed-culture fermentative bioH2.

  5. Ethanol production by the hyperthermophilic archaeon Pyrococcus furiosus by expression of bacterial bifunctional alcohol dehydrogenases.

    PubMed

    Keller, Matthew W; Lipscomb, Gina L; Nguyen, Diep M; Crowley, Alexander T; Schut, Gerrit J; Scott, Israel; Kelly, Robert M; Adams, Michael W W

    2017-02-14

    Ethanol is an important target for the renewable production of liquid transportation fuels. It can be produced biologically from pyruvate, via pyruvate decarboxylase, or from acetyl-CoA, by alcohol dehydrogenase E (AdhE). Thermophilic bacteria utilize AdhE, which is a bifunctional enzyme that contains both acetaldehyde dehydrogenase and alcohol dehydrogenase activities. Many of these organisms also contain a separate alcohol dehydrogenase (AdhA) that generates ethanol from acetaldehyde, although the role of AdhA in ethanol production is typically not clear. As acetyl-CoA is a key central metabolite that can be generated from a wide range of substrates, AdhE can serve as a single gene fuel module to produce ethanol through primary metabolic pathways. The focus here is on the hyperthermophilic archaeon Pyrococcus furiosus, which grows by fermenting sugar to acetate, CO2 and H2 . Previously, by the heterologous expression of adhA from a thermophilic bacterium, P. furiosus was shown to produce ethanol by a novel mechanism from acetate, mediated by AdhA and the native enzyme aldehyde oxidoreductase (AOR). In this study, the AOR gene was deleted from P. furiosus to evaluate ethanol production directly from acetyl-CoA by heterologous expression of the adhE gene from eight thermophilic bacteria. Only AdhEs from two Thermoanaerobacter strains showed significant activity in cell-free extracts of recombinant P. furiosus and supported ethanol production in vivo. In the AOR deletion background, the highest amount of ethanol (estimated 61% theoretical yield) was produced when adhE and adhA from Thermoanaerobacter were co-expressed.

  6. Development of combined nanofiltration and forward osmosis process for production of ethanol from pretreated rice straw.

    PubMed

    Shibuya, Masafumi; Sasaki, Kengo; Tanaka, Yasuhiro; Yasukawa, Masahiro; Takahashi, Tomoki; Kondo, Akihiko; Matsuyama, Hideto

    2017-03-28

    A membrane process combining nanofiltraion (NF) and forward osmosis (FO) was developed for the sugar concentration with the aim of high bio-ethanol production from the liquid fraction of rice straw. The commercial NF membrane, ESNA3, was more adequate for removal of fermentation inhibitors (such as acetic acid) than the FO membrane, whereas the commercial FO membrane, TFC-ES, was more adequate for concentration of the sugars than the NF membrane. The liquid fraction was subjected to the following process: NF concentration with water addition (NF(+H2O))→enzymatic hydrolysis→FO concentration. This NF(+H2O)-FO hybrid process generated a total sugar content of 107g·L(-1). Xylose-assimilating S. cerevisiae produced 24g·L(-1) ethanol from the liquid fraction that was diluted 1.5-fold and then concentrated by the NF(+H2O)-FO hybrid process. The NF(+H2O)-FO hybrid process has the potential for optimized ethanol production from pretreated lignocellulosic biomass.

  7. Thallium acetate

    Integrated Risk Information System (IRIS)

    Jump to main content . Integrated Risk Information System Recent Additions | Contact Us Search : All EPA IRIS • You are here : EPA Home • Research • Environmental Assessment • IRIS • IRIS Summaries Redirect Page As of September 30 , 2009 , the assessment summary for Thallium acetate is included in t

  8. Phenylmercuric acetate

    Integrated Risk Information System (IRIS)

    Phenylmercuric acetate ; CASRN 62 - 38 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinog

  9. Ethyl acetate

    Integrated Risk Information System (IRIS)

    Ethyl acetate ; CASRN 141 - 78 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  10. Ammonium acetate

    Integrated Risk Information System (IRIS)

    Ammonium acetate ; CASRN 631 - 61 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  11. Vinyl acetate

    Integrated Risk Information System (IRIS)

    Vinyl acetate ; CASRN 108 - 05 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  12. Mechanistic Insights on C-O and C-C Bond Activation and Hydrogen Insertion during Acetic Acid Hydrogenation Catalyzed by Ruthenium Clusters in Aqueous Medium

    SciTech Connect

    Shangguan, Junnan; Olarte, Mariefel V.; Chin, Ya-Huei

    2016-06-07

    Catalytic pathways for acetic acid (CH3COOH) and hydrogen (H2) reactions on dispersed Ru clusters in the aqueous medium and the associated kinetic requirements for C-O and C-C bond cleavages and hydrogen insertion are established from rate and isotopic assessments. CH3COOH reacts with H2 in steps that either retain its carbon backbone and lead to ethanol, ethyl acetate, and ethane (47-95 %, 1-23 %, and 2-17 % carbon selectivities, respectively) or break its C-C bond and form methane (1-43 % carbon selectivities) at moderate temperatures (413-523 K) and H2 pressures (10-60 bar, 298 K). Initial CH3COOH activation is the kinetically relevant step, during which CH3C(O)-OH bond cleaves on a metal site pair at Ru cluster surfaces nearly saturated with adsorbed hydroxyl (OH*) and acetate (CH3COO*) intermediates, forming an adsorbed acetyl (CH3CO*) and hydroxyl (OH*) species. Acetic acid turnover rates increase proportionally with both H2 (10-60 bar) and CH3COOH concentrations at low CH3COOH concentrations (<0.83 M), but decrease from first to zero order as the CH3COOH concentration and the CH3COO* coverages increase and the vacant Ru sites concomitantly decrease. Beyond the initial CH3C(O)-OH bond activation, sequential H-insertions on the surface acetyl species (CH3CO*) lead to C2 products and their derivative (ethanol, ethane, and ethyl acetate) and the competitive C-C bond cleavage of CH3CO* causes the eventual methane formation. The instantaneous carbon selectivities towards C2 species (ethanol, ethane, and ethyl acetate) increase linearly with the concentration of proton-type Hδ+ (derived from carboxylic acid dissociation) and chemisorbed H*. The selectivities towards C2 products decrease with increasing temperature, because of higher observed barriers for C-C bond cleavage than H-insertion. This study offers an interpretation of mechanism and energetics and provides kinetic evidence of carboxylic acid assisted proton-type hydrogen (Hδ+) shuffling during H

  13. Determination of the constants of affinity of FeCl3, CuCl2, and ZnCl2 for a nitrogen-containing organosilane bonded on Al2O3-cellulose acetate hybrid material surface from ethanol solution.

    PubMed

    Lazarin, Angélica M; Landers, Richard; Kholin, Yuriy V; Gushikem, Yoshitaka

    2002-10-01

    This work describes the preparation and characterization of a cellulose acetate fiber coated with Al(2)O(3), resulting in the organic-inorganic hybrid Cel/Al(2)O(3). Furthermore, the hybrid was modified by attaching organofunctional groups by reaction with the precursor reagents (RO)(3)Si(CH(2))(3)L (L=NH(2), NH(CH(2))(2)NH(2), NH(CH(2))(2)NH(CH(2))(2)NH(2), and N(2)C(3)H(3) (imidazole)), resulting in Cel/Al(2)O(3)/Si(CH(2))(3)NH(2) (1), Cel/Al(2)O(3)/Si(CH(2))(3)NH(CH(2))(2)NH(2) (2), Cel/Al(2)O(3)/Si(CH(2))(3)NH(CH(2))(2)NH(CH(2))(2)NH(2) (3), and Cel/Al(2)O(3)/Si(CH(2))(3)N(2)C(3)H(3) (4). The amounts of attached organofunctional groups were (in mmol per gram of the material) 1=1.90, 2=1.89, 3=1.66, and 4=1.35. The isotherms of adsorption of FeCl(3), CuCl(2), and ZnCl(2) by Cel/Al(2)O(3)/Si(CH(2))(3)L from ethanol solutions were obtained at 298 K. Accurate estimates of the specific sorption capacities and the heteregeneous stability constants of the immobilized metal complexes were determined with the aid of several computational procedures. It is shown that the sorptional capacities are much less than the concentrations of the attached organofunctional groups. As all sorption isotherms are fitted properly with the Langmuir isotherm equation, the effects of the energetic heterogeneity and the lateral interactions do not affect the chemisorption equilibria. The heterogeneous stability constants of the immobilized complexes are fairly high, which provides efficient removal of the metal ions from solutions by the hybrid materials.

  14. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium acetate. 184.1721 Section 184.1721 Food and... Substances Affirmed as GRAS § 184.1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3 or C2H3O2Na·3H2O, CAS Reg. No. 6131-90-4) is the sodium salt of acetic acid and occurs naturally in plant...

  15. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium acetate. 184.1721 Section 184.1721 Food and... Substances Affirmed as GRAS § 184.1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3 or C2H3O2Na·3H2O, CAS Reg. No. 6131-90-4) is the sodium salt of acetic acid and occurs naturally in plant...

  16. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium acetate. 184.1721 Section 184.1721 Food and... Substances Affirmed as GRAS § 184.1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3 or C2H3O2Na·3H2O, CAS Reg. No. 6131-90-4) is the sodium salt of acetic acid and occurs naturally in plant...

  17. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium acetate. 184.1721 Section 184.1721 Food and... Substances Affirmed as GRAS § 184.1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3 or C2H3O2Na·3H2O, CAS Reg. No. 6131-90-4) is the sodium salt of acetic acid and occurs naturally in plant...

  18. Elimination of metabolic pathways to all traditional fermentation products increases ethanol yields in Clostridium thermocellum

    DOE PAGES

    Papanek, Beth A.; Biswas, Ranjita; Rydzak, Thomas; ...

    2015-09-12

    Clostridium thermocellum has the natural ability to convert cellulose to ethanol, making it a promising candidate for consolidated bioprocessing (CBP) of cellulosic biomass to biofuels. To further improve its CBP capabilities, we study a mutant strain of C. thermocellum that was constructed (strain AG553; C. thermocellum Δhpt ΔhydG Δldh Δpfl Δpta-ack) to increase flux to ethanol by removing side product formation. Strain AG553 showed a two- to threefold increase in ethanol yield relative to the wild type on all substrates tested. On defined medium, strain AG553 exceeded 70% of theoretical ethanol yield on lower loadings of the model crystalline cellulosemore » Avicel, effectively eliminating formate, acetate, and lactate production and reducing H2 production by fivefold. On 5 g/L Avicel, strain AG553 reached an ethanol yield of 63.5% of the theoretical maximum compared with 19.9% by the wild type, and it showed similar yields on pretreated switchgrass and poplar. The elimination of organic acid production suggested that the strain might be capable of growth under higher substrate loadings in the absence of pH control. Final ethanol titer peaked at 73.4 mM in mutant AG553 on 20 g/L Avicel, at which point the pH decreased to a level that does not allow growth of C. thermocellum, likely due to CO2 accumulation. In comparison, the maximum titer of wild type C. thermocellum was 14.1 mM ethanol on 10 g/L Avicel. In conclusion, with the elimination of the metabolic pathways to all traditional fermentation products other than ethanol, AG553 is the best ethanol-yielding CBP strain to date and will serve as a platform strain for further metabolic engineering for the bioconversion of lignocellulosic biomass.« less

  19. Elimination of metabolic pathways to all traditional fermentation products increases ethanol yields in Clostridium thermocellum.

    PubMed

    Papanek, Beth; Biswas, Ranjita; Rydzak, Thomas; Guss, Adam M

    2015-11-01

    Clostridium thermocellum has the natural ability to convert cellulose to ethanol, making it a promising candidate for consolidated bioprocessing (CBP) of cellulosic biomass to biofuels. To further improve its CBP capabilities, a mutant strain of C. thermocellum was constructed (strain AG553; C. thermocellum Δhpt ΔhydG Δldh Δpfl Δpta-ack) to increase flux to ethanol by removing side product formation. Strain AG553 showed a two- to threefold increase in ethanol yield relative to the wild type on all substrates tested. On defined medium, strain AG553 exceeded 70% of theoretical ethanol yield on lower loadings of the model crystalline cellulose Avicel, effectively eliminating formate, acetate, and lactate production and reducing H2 production by fivefold. On 5 g/L Avicel, strain AG553 reached an ethanol yield of 63.5% of the theoretical maximum compared with 19.9% by the wild type, and it showed similar yields on pretreated switchgrass and poplar. The elimination of organic acid production suggested that the strain might be capable of growth under higher substrate loadings in the absence of pH control. Final ethanol titer peaked at 73.4mM in mutant AG553 on 20 g/L Avicel, at which point the pH decreased to a level that does not allow growth of C. thermocellum, likely due to CO2 accumulation. In comparison, the maximum titer of wild type C. thermocellum was 14.1mM ethanol on 10 g/L Avicel. With the elimination of the metabolic pathways to all traditional fermentation products other than ethanol, AG553 is the best ethanol-yielding CBP strain to date and will serve as a platform strain for further metabolic engineering for the bioconversion of lignocellulosic biomass.

  20. Production of ethanol from refinery waste gases. Phase 3. Engineering development. Annual report, April 1, 1995--May 15, 1996

    SciTech Connect

    Arora, D.; Basu, R.; Phillips, J.R.; Wikstrom, C.V.; Clausen, E.C; Gaddy, J.L.

    1996-11-01

    Refineries discharge large volumes of H2, CO, and CO 2 from cracking, coking, and hydrotreating operations. This R&D program seeks to develop, demonstrate, and commercialize a biological process for converting these waste gases into ethanol for blending with gasoline. A 200,000 BPD refinery could produce up to 38 million gallons ethanol per year. The program is being conducted in 3 phases: II, technology development; III, engineering development; and IV, demonstration. Phase I, exploratory development, has been completed. The research effort has yielded two strains (Isolates O-52 and C-01) which are to be used in the pilot studies to produce ethanol from CO, CO2, and H2 in petroleum waste gas. Results from single continuous stirred tank reactor (CSTR) laboratory tests have shown that 20-25 g/L ethanol can be produced with < 5 g/L acetic acid byproduct. Laboratory studies with two CSTRs in series have yielded ethanol concentrations of 30-35 g/L with 2-4 g/L acetic acid byproduct. Water recycle from distillation back to the fermenter shows that filtration of the water before distillation eliminates the recycle of toxic materials back to the fermenter. Product recovery in the process will use direct distillation to the azeotrope, followed by adsorption to produce neat ethanol. This is less energy intensive than e.g. solvent extraction, azeotropic distillation, or pervaporation. Economic projections are quite attractive; the economics are refinery stream dependent and thus vary depending on refinery location and operation.

  1. Perfusion culture process plus H2O2 stimulation for efficient astaxanthin production by Xanthophyllomyces dendrorhous.

    PubMed

    Liu, Yuan Shuai; Wu, Jian Yong

    2007-06-15

    A semicontinuous perfusion culture process (repeated medium renewal with cell retention) was evaluated together with batch and repeated fed-batch processes for astaxanthin production in shake-flask cultures of Xanthophyllomyces dendrorhous. The perfusion process with 25% medium renewal every 12 h for 10 days achieved a biomass density of 65.6 g/L, a volumetric astaxanthin yield of 52.5 mg/L, and an astaxanthin productivity of 4.38 mg/L-d, which were 8.4-fold, 5.6-fold, and 2.3-fold of those in the batch process, 7.8 g/L, 9.4 mg/L, and 1.88 mg/L-d, respectively. The incorporation of hydrogen peroxide (H(2)O(2)) stimulation of astaxanthin biosynthesis into the perfusion process further increased the astaxanthin yield to 58.3 mg/L and the productivity to 4.86 mg/L-d. The repeated fed-batch process with 8 g/L glucose and 4 g/L corn steep liquor fed every 12 h achieved 42.2 g/L biomass density, 36.5 mg/L astaxanthin yield, and 3.04 mg/L-d astaxanthin productivity. The lower biomass and astaxanthin productivity in the repeated fed-batch than in the perfusion process may be mostly attributed to the accumulation of inhibitory metabolites such as ethanol and acetic acid in the culture. The study shows that perfusion process plus H(2)O(2) stimulation is an effective strategy for enhanced astaxanthin production in X. dendrorhous cultures.

  2. Biological production of ethanol fom coal

    SciTech Connect

    Not Available

    1992-05-01

    Research is continuing in an attempt to increase both the ethanol concentration and product ratio using C. ljungdahlii. The purpose of this report is to present data (acetate to ethanol) utilizing a medium prepared especially for C. ljungdahlii. Medium development studies are presented, as well as reactor studies with the new medium in batch reactors. Continuous stirred tank reactor (CSTR) with cell recycle. The use of this new medium has resulted in significant improvements in cell concentration, ethanol concentration and product ratio.

  3. Ethanol Metabolism and Osmolarity Modify Behavioral Responses to Ethanol in C. elegans

    PubMed Central

    Alaimo, Joseph T.; Davis, Scott J.; Song, Sam S.; Burnette, Christopher R.; Grotewiel, Mike; Shelton, Keith L.; Pierce-Shimomura, Jonathan T.; Davies, Andrew G.; Bettinger, Jill C.

    2012-01-01

    Background Ethanol is metabolized by a two-step process in which alcohol dehydrogenase (ADH) oxidizes ethanol to acetaldehyde, which is further oxidized to acetate by aldehyde dehydrogenase (ALDH). Although variation in ethanol metabolism in humans strongly influences the propensity to chronically abuse alcohol, few data exist on the behavioral effects of altered ethanol metabolism. Here, we used the nematode C. elegans to directly examine how changes in ethanol metabolism alter behavioral responses to alcohol during an acute exposure. Additionally, we investigated ethanol solution osmolarity as a potential explanation for contrasting published data on C. elegans ethanol sensitivity. Methods We developed a gas chromatography assay and validated a spectrophotometric method to measure internal ethanol in ethanol-exposed worms. Further, we tested the effects of mutations in ADH and ALDH genes on ethanol tissue accumulation and behavioral sensitivity to the drug. Finally, we tested the effects of ethanol solution osmolarity on behavioral responses and tissue ethanol accumulation. Results Only a small amount of exogenously applied ethanol accumulated in the tissues of C. elegans and consequently their tissue concentrations were similar to those that intoxicate humans. Independent inactivation of an ADH-encoding gene (sodh-1) or an ALDH-encoding gene (alh-6 or alh-13) increased the ethanol concentration in worms and caused hypersensitivity to the acute sedative effects of ethanol on locomotion. We also found that the sensitivity to the depressive effects of ethanol on locomotion is strongly influenced by the osmolarity of the exogenous ethanol solution. Conclusions Our results indicate that ethanol metabolism via ADH and ALDH has a statistically discernable but surprisingly minor influence on ethanol sedation and internal ethanol accumulation in worms. In contrast, the osmolarity of the medium in which ethanol is delivered to the animals has a more substantial effect on

  4. Bacterial Community Profiling of H2/CO2 or Formate-Utilizing Acetogens Enriched from Diverse Ecosystems

    NASA Astrophysics Data System (ADS)

    Han, R.; Zhang, L.; Fu, B.; Liu, H.

    2014-12-01

    Synthetic gases are usually generated from either cellulosic agricultural waste combustion or industrial release and could be subsequently transformed into acetate, ethanol, and/or butyrate by homoacetogenic bacteria, which commonly possess reductive acetyl-CoA synthesis pathway. Homoacetogen-based syngas fermentation technology provides an alternative solution to link greenhouse gas emission control and cellulosic solid waste treatment with biofuels production. The objective of our current project is to hunt for homoacetogens with capabilities of highly efficiently converting syngases to chemical solvents. In this study, we evaluated homoacetogens population dynamics during enrichments and pinpointed dominant homoacetogens representing diverse ecosystems enriched by different substrates. We enriched homoacetogens from four different samples including waste activate sludge, freshwater sediment, anaerobic methanogenic sludge, and cow manure using H2/CO2 (4:1) or formate as substrate for homoacetogen enrichment. Along with the formyltetrahydrofolate synthetase (FTHFS) gene (fhs gene)-specific real time qPCR assay and Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis, 16S rRNA based 454 high-throughput pyrosequencing was applied to reveal the population dynamic and community structure during enrichment from different origins. Enrichment of homoacetogenic populations coincided with accumulations of short chain fatty acids such as acetate and butyrate. 454 high-throughput pyrosequencing revealed Firmicutes and Spirochaetes populations became dominant while the overall microbial diversity decreased after enrichment. The most abundant sequences among the four origins belonged to the following phyla: Firmicutes, Spirochaetes, Proteobacteria, and Bacteroidetes, accounting for 62.1%-99.1% of the total reads. The major putative homoacetogenic species enriched on H2/CO2 or formate belonged to Clostridium spp., Acetobacterium spp., Acetoanaerobium spp

  5. Acetic acid removal from corn stover hydrolysate using ethyl acetate and the impact on Saccharomyces cerevisiae bioethanol fermentation.

    PubMed

    Aghazadeh, Mahdieh; Ladisch, Michael R; Engelberth, Abigail S

    2016-07-08

    Acetic acid is introduced into cellulose conversion processes as a consequence of composition of lignocellulose feedstocks, causing significant inhibition of adapted, genetically modified and wild-type S. cerevisiae in bioethanol fermentation. While adaptation or modification of yeast may reduce inhibition, the most effective approach is to remove the acetic acid prior to fermentation. This work addresses liquid-liquid extraction of acetic acid from biomass hydrolysate through a pathway that mitigates acetic acid inhibition while avoiding the negative effects of the extractant, which itself may exhibit inhibition. Candidate solvents were selected using simulation results from Aspen Plus™, based on their ability to extract acetic acid which was confirmed by experimentation. All solvents showed varying degrees of toxicity toward yeast, but the relative volatility of ethyl acetate enabled its use as simple vacuum evaporation could reduce small concentrations of aqueous ethyl acetate to minimally inhibitory levels. The toxicity threshold of ethyl acetate, in the presence of acetic acid, was found to be 10 g L(-1) . The fermentation was enhanced by extracting 90% of the acetic acid using ethyl acetate, followed by vacuum evaporation to remove 88% removal of residual ethyl acetate along with 10% of the broth. NRRL Y-1546 yeast was used to demonstrate a 13% increase in concentration, 14% in ethanol specific production rate, and 11% ethanol yield. This study demonstrated that extraction of acetic acid with ethyl acetate followed by evaporative removal of ethyl acetate from the raffinate phase has potential to significantly enhance ethanol fermentation in a corn stover bioethanol facility. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:929-937, 2016.

  6. Ethanol poisoning

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002644.htm Ethanol poisoning To use the sharing features on this page, please enable JavaScript. Ethanol poisoning is caused by drinking too much alcohol. ...

  7. Effects of Hydrogen Pressure during Growth and Effects of Pregrowth with Hydrogen on Acetate Degradation by Methanosarcina Species.

    PubMed

    Boone, D R; Menaia, J A; Boone, J E; Mah, R A

    1987-01-01

    Methanosarcina barkeri 227 and Methanosarcina mazei S-6 grew with acetate as the substrate; we found little effect of H(2) on the rate of aceticlastic growth in the presence of various H(2) pressures between 2 and 810 Pa. We used physical (H(2) addition or flushing the headspace to remove H(2)) and biological (H(2)-producing or -utilizing bacteria in cocultures) methods for controlling H(2) pressure in Methanosarcina cultures growing on acetate. Added H(2) (ca. 100 Pa) was removed rapidly (a few hours) by M. barkeri and slowly (within a day) by M. mazei. When the H(2) produced by the aceticlastic methanogens was removed by coculturing with an H(2)-using Desulfovibrio sp., the H(2) pressure was about 2.2 Pa. Under these conditions the stoichiometry of aceticlastic methanogenesis did not change. H(2)-grown inocula of M. barkeri grew with acetate as the sole catabolic substrate if the inoculum culture was transferred during logarithmic growth to acetate-containing medium or if the transfer was accomplished within 1 or 2 days after exhaustion of H(2). H(2)-grown cultures incubated for 4 or more days after exhaustion of H(2) were able to grow with H(2) but not with acetate as the sole catabolic substrate. Addition of small quantities of H(2) to acetate-containing medium permitted these cultures to initiate growth on acetate.

  8. In situ hydrogen, acetone, butanol, ethanol and microdiesel production by Clostridium acetobutylicum ATCC 824 from oleaginous fungal biomass.

    PubMed

    Hassan, Elhagag Ahmed; Abd-Alla, Mohamed Hemida; Bagy, Magdy Mohamed Khalil; Morsy, Fatthy Mohamed

    2015-08-01

    An in situ batch fermentation technique was employed for biohydrogen, acetone, butanol, ethanol and microdiesel production from oleaginous fungal biomass using the anaerobic fermentative bacterium Clostridium acetobutylicum ATCC 824. Oleaginous fungal Cunninghamella echinulata biomass which has ability to accumulate up to 71% cellular lipid was used as the substrate carbon source. The maximum cumulative hydrogen by C. acetobutylicum ATCC 824 from crude C. echinulata biomass was 260 ml H2 l(-1), hydrogen production efficiency was 0.32 mol H2 mole(-1) glucose and the hydrogen production rate was 5.2 ml H2 h(-1). Subsequently, the produced acids (acetic and butyric acids) during acidogenesis phase are re-utilized by ABE-producing clostridia and converted into acetone, butanol, and ethanol. The total ABE produced by C. acetobutylicum ATCC 824 during batch fermentation was 3.6 g l(-1) from crude fungal biomass including acetone (1.05 g l(-1)), butanol (2.19 g l(-1)) and ethanol (0.36 g l(-1)). C. acetobutylicum ATCC 824 has ability to produce lipolytic enzymes with a specific activity 5.59 U/mg protein to hydrolyze ester containing substrates. The lipolytic potential of C. acetobutylicum ATCC 824 was used as a biocatalyst for a lipase transesterification process using the produced ethanol from ABE fermentation for microdiesel production. The fatty acid ethyl esters (microdiesel) generated from the lipase transesterification of crude C. echinulata dry mass was analyzed by GC/MS as 15.4% of total FAEEs. The gross energy content of biohydrogen, acetone, butanol, ethanol and biodiesel generated through C. acetobutylicum fermentation from crude C. echinulata dry mass was 3113.14 kJ mol(-1). These results suggest a possibility of integrating biohydrogen, acetone, butanol and ethanol production technology by C. acetobutylicum with microdiesel production from crude C. echinulata dry mass and therefore improve the feasibility and commercialization of bioenergy production.

  9. Ethanol Basics

    SciTech Connect

    2015-01-30

    Ethanol is a widely-used, domestically-produced renewable fuel made from corn and other plant materials. More than 96% of gasoline sold in the United States contains ethanol. Learn more about this alternative fuel in the Ethanol Basics Fact Sheet, produced by the U.S. Department of Energy's Clean Cities program.

  10. Acetic acid production from food wastes using yeast and acetic acid bacteria micro-aerobic fermentation.

    PubMed

    Li, Yang; He, Dongwei; Niu, Dongjie; Zhao, Youcai

    2015-05-01

    In this study, yeast and acetic acid bacteria strains were adopted to enhance the ethanol-type fermentation resulting to a volatile fatty acids yield of 30.22 g/L, and improve acetic acid production to 25.88 g/L, with food wastes as substrate. In contrast, only 12.81 g/L acetic acid can be obtained in the absence of strains. The parameters such as pH, oxidation reduction potential and volatile fatty acids were tested and the microbial diversity of different strains and activity of hydrolytic ferment were investigated to reveal the mechanism. The optimum pH and oxidation reduction potential for the acetic acid production were determined to be at 3.0-3.5 and -500 mV, respectively. Yeast can convert organic matters into ethanol, which is used by acetic acid bacteria to convert the organic wastes into acetic acid. The acetic acid thus obtained from food wastes micro-aerobic fermentation liquid could be extracted by distillation to get high-pure acetic acid.

  11. Development of corn silk as a biocarrier for Zymomonas mobilis biofilms in ethanol production from rice straw.

    PubMed

    Todhanakasem, Tatsaporn; Tiwari, Rashmi; Thanonkeo, Pornthap

    2016-01-01

    Z. mobilis cell immobilization has been proposed as an effective means of improving ethanol production. In this work, polystyrene and corn silk were used as biofilm developmental matrices for Z. mobilis ethanol production with rice straw hydrolysate as a substrate. Rice straw was hydrolyzed by dilute sulfuric acid (H2SO4) and enzymatic hydrolysis. The final hydrolysate contained furfural (271.95 ± 76.30 ppm), 5-hydroxymethyl furfural (0.07 ± 0.00 ppm), vanillin (1.81 ± 0.00 ppm), syringaldehyde (5.07 ± 0.83 ppm), 4-hydroxybenzaldehyde (4-HB) (2.39 ± 1.20 ppm) and acetic acid (0.26 ± 0.08%). Bacterial attachment or biofilm formation of Z. mobilis strain TISTR 551 on polystyrene and delignified corn silk carrier provided significant ethanol yields. Results showed up to 0.40 ± 0.15 g ethanol produced/g glucose consumed when Z. mobilis was immobilized on a polystyrene carrier and 0.51 ± 0.13 g ethanol produced/g glucose consumed when immobilized on delignified corn silk carrier under batch fermentation by Z. mobilis TISTR 551 biofilm. The higher ethanol yield from immobilized, rather than free living, Z. mobilis could possibly be explained by a higher cell density, better control of anaerobic conditions and higher toxic tolerance of Z. mobilis biofilms over free cells.

  12. Evaluation of H2CHXdedpa, H2dedpa- and H2CHXdedpa-N,N'-propyl-2-NI ligands for (64)Cu(ii) radiopharmaceuticals.

    PubMed

    Ramogida, Caterina F; Boros, Eszter; Patrick, Brian O; Zeisler, Stefan K; Kumlin, Joel; Adam, Michael J; Schaffer, Paul; Orvig, Chris

    2016-08-16

    The chiral acyclic "pa" ligand (pa = picolinic acid) H2CHXdedpa (N4O2) and two NI-containing dedpa analogues (H2CHXdedpa-N,N'-propyl-2-NI, H2dedpa-N,N'-propyl-2-NI, NI = nitroimidazole) were studied as chelators for copper radiopharmaceuticals (CHX = cyclohexyl, H2dedpa = 1,2-[[carboxypyridin-2-yl]methylamino]ethane). The hexadentate ligand H2CHXdedpa was previously established as a superb system for (67/68)Ga radiochemistry. The solid state X-ray crystal structures of [Cu(CHXdedpa-N,N'-propyl-2-NI)] and [Cu(dedpa-N,N'-propyl-2-NI)] reveal the predicted hexadentate, distorted octahedral binding of the copper(ii) ion. Cyclic voltammetry of [Cu(dedpa-N,N'-propyl-2-NI)] shows that there is one reversible couple associated with the NI redox, and one irreversible but reproducible couple attributed to the Cu(ii)/Cu(i) redox cycle. Quantitative radiolabeling (>99%) of CHXdedpa(2-) and (dedpa-N,N'-propyl-2-NI)(2-) with (64)Cu was achieved under fast and efficient labeling conditions (10 min, RT, 0.5 M sodium acetate buffer, pH 5.5) at ligand concentrations as low as 10(-6) M. In vitro kinetic inertness studies of the (64)Cu labelled complexes were studied in human serum at 37 °C over 24 hours; [(64)Cu(CHXdedpa)] was found to be 98% stable compared to previously investigated [(64)Cu(dedpa)] which was only 72% intact after 24 hours.

  13. The effect of ZnO addition on H2O activation over Co/ZrO2 catalysts

    SciTech Connect

    Davidson, Stephen D.; Sun, Junming; Wang, Yong

    2016-07-01

    The effect of ZnO addition on the dissociation of H2O and subsequent effects on cobalt oxidation state and ethanol reaction pathway were investigated over Co/ZrO2 catalyst during ethanol steam reforming (ESR). Catalyst physical properties were characterized by BET, XRD, and TEM. To characterize the catalysts ability to dissociate H2O, Raman spectroscopy, H2O-TPO, and pulsed H2O oxidation coupled with H2-TPR were used. It was found that the addition of ZnO to cobalt supported on ZrO2 decreased the activity for H2O dissociation, leading to a lower degree of cobalt oxidation. The decreased H2O dissociation was also found to affect the reaction pathway, evidenced by a shift in liquid product selectivity away from acetone and towards acetaldehyde.

  14. H2AFV — EDRN Public Portal

    Cancer.gov

    H2AFV is a variant histone H2A which replaces conventional H2A in a subset of nucleosomes. The nucleosome is a histone octamer containing two molecules each of H2A, H2B, H3 and H4 assembled in one H3-H4 heterotetramer and two H2A-H2B heterodimers. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template (the octamer wraps approximately 147 bp of DNA). Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling. Additionally, H2AFV may be involved in the formation of constitutive heterochromatin, and may be required for chromosome segregation during cell division.

  15. Histone H2A significantly enhances in vitro DNA transfection.

    PubMed Central

    Balicki, D.; Beutler, E.

    1997-01-01

    BACKGROUND: Gene transfer is a potential treatment modality of genetic disease. Efficient, practical methods of DNA transfection are currently under investigation. MATERIALS AND METHODS: A beta-galactosidase reporter plasmid interacted electrostatically with histones, poly-L-Lys, poly-L-Arg, and a combination of poly-L-Lys and poly-L-Arg. This complex was then used to transfect COS-7 cells. beta-galactosidase activity was quantified and used to compare the efficiency of gene transfection in vitro. A comparison was also made of DNA transfection with the most active histone subclass, i.e., histone H2A, in the absence and presence of an anionic liposome. RESULTS: There was a marked increase in DNA transfection in the presence of histone H2A when compared with the control, whereas each of the other histones and polycations showed little, if any, effect. The extent of activation depends strongly on the DNA/histone ratio and is also a function of the molarity of the final Tris-acetate, pH 8, solution. The anionic liposomes used demonstrated an inhibitory effect. CONCLUSIONS: Histone H2A significantly enhances in vitro DNA transfection whereas other histones and anionic liposomes do not. A study of the difference between histone H2A and other histone subclasses may serve to clarify some of the mechanisms and the essential components of efficient gene delivery. PMID:9407553

  16. Species specificity and individual variability of sea urchin sperm H2B histones.

    PubMed

    de Petrocellis, B; de Petrocellis, L; Lancieri, M; Geraci, G

    1980-01-01

    Total histones from the sperms and embryos of the sea urchins Paracentrotus lividus, Arbacia lixula, Psammechinus microtuberculatus and Sphaerechinus granularis hae been fractionated into the component molecules by electrophoretic analyses in SDS, in urea-acetic acid and in Triton-urea-acetic acid. Sperm H2B histones are in all cases different from those of the corresponding embryonic chromatins. Each sea urchin species has distinctive variants of the sperm H2B histones that are fractionated by electrophoresis in SDS acrylamide gel into two to four components forming a new class of lower mobility. This analytical method shows that individuals of the same species have different assortments of the H2B components. Electrophoretic analyses in Triton-urea also show multiple components for H2B but the patterns are similar in the different individuals.

  17. Solution structure of the isolated histone H2A-H2B heterodimer

    PubMed Central

    Moriwaki, Yoshihito; Yamane, Tsutomu; Ohtomo, Hideaki; Ikeguchi, Mitsunori; Kurita, Jun-ichi; Sato, Masahiko; Nagadoi, Aritaka; Shimojo, Hideaki; Nishimura, Yoshifumi

    2016-01-01

    During chromatin-regulated processes, the histone H2A-H2B heterodimer functions dynamically in and out of the nucleosome. Although detailed crystal structures of nucleosomes have been established, that of the isolated full-length H2A-H2B heterodimer has remained elusive. Here, we have determined the solution structure of human H2A-H2B by NMR coupled with CS-Rosetta. H2A and H2B each contain a histone fold, comprising four α-helices and two β-strands (α1–β1–α2–β2–α3–αC), together with the long disordered N- and C-terminal H2A tails and the long N-terminal H2B tail. The N-terminal αN helix, C-terminal β3 strand, and 310 helix of H2A observed in the H2A-H2B nucleosome structure are disordered in isolated H2A-H2B. In addition, the H2A α1 and H2B αC helices are not well fixed in the heterodimer, and the H2A and H2B tails are not completely random coils. Comparison of hydrogen-deuterium exchange, fast hydrogen exchange, and {1H}-15N hetero-nuclear NOE data with the CS-Rosetta structure indicates that there is some conformation in the H2A 310 helical and H2B Lys11 regions, while the repression domain of H2B (residues 27–34) exhibits an extended string-like structure. This first structure of the isolated H2A-H2B heterodimer provides insight into its dynamic functions in chromatin. PMID:27181506

  18. Elucidating acetogenic H2 consumption in dark fermentation using flux balance analysis.

    PubMed

    Lalman, Jerald A; Chaganti, Subba Rao; Moon, Chungman; Kim, Dong-Hoon

    2013-10-01

    In this study, a flux balance analysis (FBA) was adopted to estimate the activity of acetogenic H2-consuming reaction. Experimental data at different substrate concentrations of 10, 20, and 30 g COD/L showing the lowest, medium, and highest H2 yields, respectively, were used in the FBA to calculate the fluxes. It was interesting to note that the hydrogenase activity based on R12 (2Fd(+)+2H(+)→2Fd(2+)+H2, ferredoxin (Fd)) flux was most active at 10 g COD/L. The flux of R17 (4H2+2CO2→CH3COOH), a mechanism for reutilizing produced H2, increased in steps of 0.030, 0.119, and 0.467 as the substrate concentration decreased. Contradictory to our general understanding, acetate production found to have a negligible or even negative effect on the final H2 yield in dark fermentation.

  19. Fuel ethanol

    SciTech Connect

    Not Available

    1989-02-01

    This report discusses the Omnibus Trade and Competitiveness Act of 1988 which requires GAO to examine fuel ethanol imports from Central America and the Caribbean and their impact on the U.S. fuel ethanol industry. Ethanol is the alcohol in beverages, such as beer, wine, and whiskey. It can also be used as a fuel by blending with gasoline. It can be made from renewable resources, such as corn, wheat, grapes, and sugarcane, through a process of fermentation. This report finds that, given current sugar and gasoline prices, it is not economically feasible for Caribbean ethanol producers to meet the current local feedstock requirement.

  20. Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells.

    PubMed

    Sim, Junyoung; An, Junyeong; Elbeshbishy, Elsayed; Ryu, Hodon; Lee, Hyung-Sool

    2015-11-01

    Cathode potential and O2 supply methods were investigated to improve H2O2 synthesis in an electrochemical cell, and optimal cathode conditions were applied for microbial electrochemical cells (MECs). Using aqueous O2 for the cathode significantly improved current density, but H2O2 conversion efficiency was negligible at 0.3-12%. Current density decreased for passive O2 diffusion to the cathode, but H2O2 conversion efficiency increased by 65%. An MEC equipped with a gas diffusion cathode was operated with acetate medium and domestic wastewater, which presented relatively high H2O2 conversion efficiency from 36% to 47%, although cathode overpotential was fluctuated. Due to different current densities, the maximum H2O2 production rate was 141 mg H2O2/L-h in the MEC fed with acetate medium, but it became low at 6 mg H2O2/L-h in the MEC fed with the wastewater. Our study clearly indicates that improving anodic current density and mitigating membrane fouling would be key parameters for large-scale H2O2-MECs.

  1. H2 Metabolism in Photosynthetic Organisms

    PubMed Central

    Ben-Amotz, Ami; Erbes, David L.; Riederer-Henderson, Mary Ann; Peavey, Dwight G.; Gibbs, Martin

    1975-01-01

    Dark H2 metabolism was studied in marine and fresh water red algae, the green alga, Chlamydomonas, and mosses. A time variable and temperature-sensitive anaerobic incubation was required prior to H2 evolution. H2 evolution was sensitive to disalicylidenepropanediamine. An immediate H2 uptake was observed in these algae. Immediate dark H2 uptake but no evolution was observed in the mosses. A cell-free hydrogenase preparation was obtained from anaerobically adapted Chlamydomonas reinhardii by means of sonic oscillation. The hydrogenase was not sedimented at 100,000g. It catalyzed the reduction of methylene blue, p-benzoquinone, NAD, NADP, but not spinach ferredoxin. H2 evolution was noted with dithionite and with reduced methyl viologen as donors but not with reduced spinach ferredoxin. Similarly, hydrogenase activities were not affected by disalicylidenepropanediamine. The pH optima for H2 evolution and for H2 uptake were 7.2 and 7.5 to 9.5, respectively. Extracts prepared from the anaerobically adapted red alga, Chondrus crispus, and the moss, Leptobryum pyriforme, consumed but did not evolve H2. Uptake was slightly stimulated by methylene blue. It is proposed that red algae and mosses appear to metabolize H2 by a different pathway than Chlamydomonas. PMID:16659260

  2. The beneficial effect of BPC 157, a 15 amino acid peptide BPC fragment, on gastric and duodenal lesions induced by restraint stress, cysteamine and 96% ethanol in rats. A comparative study with H2 receptor antagonists, dopamine promotors and gut peptides.

    PubMed

    Sikiric, P; Seiwerth, S; Grabarevic, Z; Petek, M; Rucman, R; Turkovic, B; Rotkvic, I; Jagic, V; Duvnjak, M; Mise, S

    1994-01-01

    The protection of stomach and duodenum in conjecture with anti-inflammatory effect was demonstrated for a novel 15 amino acid peptide, coded BPC 157, a fragment of the recently discovered gastric juice peptide BPC. BPC 157 (i.p./i.g.) was investigated in rats in comparison with several reference standards in three experimental ulcer models (48 h-restraint stress, subcutaneous cysteamine, intragastrical 96% ethanol ulcer tests) (pre-/co-/post-treatment). Only BPC 157 regimens were consistently effective in all of the tested models. On the other hand, bromocriptine, amantadine, famotidine, cimetidine and somatostatin were ineffective (restraint stress). A dose-dependent protection (cysteamine) and/or partial positive effect (related to treatment conditions) (ethanol), was obtained with glucagon, NPY and secretin whereas CCK/26-30/was not effective. Based on Monastral blue studies BPC 157 beneficial effect appears to be related to a strong endothelial protection.

  3. Microhydration of Neutral and Charged Acetic Acid.

    PubMed

    Krishnakumar, Parvathi; Maity, Dilip Kumar

    2017-01-19

    A systematic theoretical study has been carried out on the effect of sequential addition of water molecules to neutral and mono positively charged acetic acid molecules by applying first principle based electronic structure theory. Geometry, dipole moment, and polarizability of hydrated clusters of neutral and mono positively charged acetic acid of the type CH3COOH·nH2O (n = 1-8) and [CH3COOH·nH2O](+) (n = 1, 2) are calculated at the ωB97X-D/aug-cc-pVDZ level of theory. Free energies of formation of the hydrated acid clusters, at different temperatures and pressures are determined. Solvent stabilization energy and interaction energy are also calculated at the CCSD(T)/6-311++G(d,p) level of theory. It is observed that in the case of neutral acetic acid, proton transfer from the acid molecule to solvent water molecules does not occur even with eight water molecules and the acid molecule remains in the undissociated form. High-energy equilibrium structures showing dissociation of acetic acid are obtained in case of hexahydrated and larger hydrated clusters only. However, dissociation of mono positively charged acetic acid occurs with just two water molecules. Interestingly, it is noted that in the case of dissociation, calculated bond dipole moments of the dissociating bonds of acetic acid in microhydated clusters shows a characteristic feature. IR spectra of CH3COOH·nH2O (n = 1-8) and [CH3COOH·nH2O](+) (n = 1-3) clusters are simulated and compared with the available experimental data.

  4. γH2AX and cancer

    PubMed Central

    Bonner, William M.; Redon, Christophe E.; Dickey, Jennifer S.; Nakamura, Asako J.; Sedelnikova, Olga A.; Solier, Stéphanie; Pommier, Yves

    2011-01-01

    Histone H2AX phosphorylation on a serine four residues from the carboxyl terminus (producing γH2AX) is a sensitive marker for DNA double-strand breaks (DSBs). DSBs may lead to cancer but, paradoxically, are also used to kill cancer cells. Using γH2AX detection to determine the extent of DSB induction may help to detect precancerous cells, to stage cancers, to monitor the effectiveness of cancer therapies and to develop novel anticancer drugs. PMID:19005492

  5. Photolysis of H2O-H2O2 Mixtures: The Destruction of H2O2

    NASA Technical Reports Server (NTRS)

    Loeffler, M. J.; Fama, M.; Baragiola, R. A.; Carlson, R. W.

    2013-01-01

    We present laboratory results on the loss of H2O2 in solid H2O + H2O2 mixtures at temperatures between 21 and 145 K initiated by UV photolysis (193 nm). Using infrared spectroscopy and microbalance gravimetry, we measured the decrease of the 3.5 micrometer infrared absorption band during UV irradiation and obtained a photodestruction cross section that varies with temperature, being lowest at 70 K. We use our results, along with our previously measured H2O2 production rates via ionizing radiation and ion energy fluxes from the spacecraft to compare H2O2 creation and destruction at icy satellites by ions from their planetary magnetosphere and from solar UV photons. We conclude that, in many cases, H2O2 is not observed on icy satellite surfaces because the H2O2 photodestruction rate is much higher than the production rate via energetic particles, effectively keeping the H2O2 infrared signature at or below the noise level.

  6. Flammability and Explosion Limits of H2 and H2/CO: A Literature Review

    DTIC Science & Technology

    1992-09-10

    I, SMC-TR-93-19 AD-A2 4 896AEROSPACE REPORT NOAD-A264 896 TR-92(2534)- ° Flammability and Explosion Limits of H2 and H2/CO: A Literature Review ...ELEMENT NO. NO. NO. ACCESSION NO 11. TITLE (Include Semrmly Ctassltjcation) Flammability and Explosion Limits of H2 and H2 /CO: A Literature Review 12...The literature related to the flammability and explosion limits of H2/O2 H2/0 2 /diluent. CO/O 2 . CO/H,/O 2 , and CO/H2/air mixtures is reviewed

  7. Combined inactivation of the Clostridium cellulolyticum lactate and malate dehydrogenase genes substantially increases ethanol yield from cellulose and switchgrass fermentations

    SciTech Connect

    Li, Yongchao; Tschaplinski, Timothy J; Engle, Nancy L; Hamilton, Choo Yieng; Rodriguez, Jr., Miguel; Liao, James C; Schadt, Christopher Warren; Guss, Adam M; Yang, Yunfeng; Graham, David E

    2012-01-01

    Background: The model bacterium Clostridium cellulolyticum efficiently hydrolyzes crystalline cellulose and hemicellulose, using cellulosomes to degrade lignocellulosic biomass. Although it imports and ferments both pentose and hexose sugars to produce a mixture of ethanol, acetate, lactate, H2 and CO2, the proportion of ethanol is low, which impedes its use in consolidated bioprocessing for biofuels. Therefore genetic engineering will likely be required to improve the ethanol yield. Random mutagenesis, plasmid transformation, and heterologous expression systems have previously been developed for C. cellulolyticum, but targeted mutagenesis has not been reported for this organism. Results: The first targeted gene inactivation system was developed for C. cellulolyticum, based on a mobile group II intron originating from the Lactococcus lactis L1.LtrB intron. This markerless mutagenesis system was used to disrupt both the paralogous L-lactate dehydrogenase (Ccel_2485; ldh) and L-malate dehydrogenase (Ccel_0137; mdh) genes, distinguishing the overlapping substrate specificities of these enzymes. Both mutations were then combined in a single strain. This double mutant produced 8.5-times more ethanol than wild-type cells growing on crystalline cellulose. Ethanol constituted 93% of the major fermentation products (by molarity), corresponding to a molar ratio of ethanol to organic acids of 15, versus 0.18 in wild-type cells. During growth on acid-pretreated switchgrass, the double mutant also produced four-times as much ethanol as wild-type cells. Detailed metabolomic analyses identified increased flux through the oxidative branch of the mutant s TCA pathway. Conclusions: The efficient intron-based gene inactivation system produced the first gene-targeted mutations in C. cellulolyticum. As a key component of the genetic toolbox for this bacterium, markerless targeted mutagenesis enables functional genomic research in C. cellulolyticum and rapid genetic engineering to

  8. Deletion of Type I glutamine synthetase deregulates nitrogen metabolism and increases ethanol production in Clostridium thermocellum.

    PubMed

    Rydzak, Thomas; Garcia, David; Stevenson, David M; Sladek, Margaret; Klingeman, Dawn M; Holwerda, Evert K; Amador-Noguez, Daniel; Brown, Steven D; Guss, Adam M

    2017-04-08

    Clostridium thermocellum rapidly deconstructs cellulose and ferments resulting hydrolysis products into ethanol and other products, and is thus a promising platform organism for the development of cellulosic biofuel production via consolidated bioprocessing. While recent metabolic engineering strategies have targeted eliminating canonical fermentation products (acetate, lactate, formate, and H2), C. thermocellum also secretes amino acids, which has limited ethanol yields in engineered strains to approximately 70% of the theoretical maximum. To investigate approaches to decrease amino acid secretion, we attempted to reduce ammonium assimilation by deleting the Type I glutamine synthetase (glnA) in an essentially wild type strain of C. thermocellum. Deletion of glnA reduced levels of secreted valine and total amino acids by 53% and 44% respectively, and increased ethanol yields by 53%. RNA-seq analysis revealed that genes encoding the RNF-complex were more highly expressed in ΔglnA and may have a role in improving NADH-availability for ethanol production. While a significant up-regulation of genes involved in nitrogen assimilation and urea uptake suggested that deletion of glnA induces a nitrogen starvation response, metabolomic analysis showed an increase in intracellular glutamine levels indicative of nitrogen-rich conditions. We propose that deletion of glnA causes deregulation of nitrogen metabolism, leading to overexpression of nitrogen metabolism genes and, in turn, elevated glutamine levels. Here we demonstrate that perturbation of nitrogen assimilation is a promising strategy to redirect flux from the production of nitrogenous compounds toward biofuels in C. thermocellum.

  9. Biological production of ethanol from coal

    SciTech Connect

    Not Available

    1990-01-01

    The fermentation pH has been observed to be the key parameter affecting the ratio of ethanol to acetate produced by Clostridium ljungdahlii. The effects of controlled pH on cell growth and product formation by C. ljungdahlii were measured. It was found that cell concentration and acetate concentration increased with pH, while the ethanol concentration was highest at the lower pH. The molar product ratio of ethanol to acetate was 0.74 at pH 4.0, 0.39 at pH 4.5 and 0.12 at pH 5.0. Future experiments will concentrate on studying other important parameters such as agitation rate and nutrients concentrations with controlled pH as a preclude to continuous reactor studies.

  10. Modeling the Interaction of H2 on Root Exudate Degradation and Methanogenesis in Wetland Sediments

    NASA Astrophysics Data System (ADS)

    Pal, D. S.; Jaffe, P. R.

    2014-12-01

    CH4 is produced in wetland sediments from the microbial degradation of organic carbon through multiple fermentation steps and methanogenesis pathways. There are many potential sources of carbon for methananogenesis; in vegetated wetland sediments, microbial communities consume root exudates as a major source of organic carbon. In many methane models propionate is used as a model carbon molecule. This simple sugar is fermented into acetate and H2, acetate is transformed to methane and CO2 while the H2 and CO2 is synthesized to form an additional CH4 molecule. The hydrogenotrophic pathway involves the equilibrium of two dissolved gases, CH4 and H2. In an effort to limit CH4 emissions from wetlands, there has been growing interest in finding ways to limit plant transport of soil gases through root systems. While this may decrease the direct emissions of methane, there is little understanding about how H2 dynamics may feedback into overall methane production. Since H2 is used in methane production and produced in propionate fermentation, increased subsurface H2 concentrations can simultaneously inhibit propionate fermentation and acetate production and enhance hydrogenotrophic methanogenesis. For this study, we incubated soil samples from vegetated wetland sediments with propionate or acetate and four different hydrogen concentrations. The headspaces from these incubations were simultaneously analyzed for H2 and CH4 at multiple time points over two months. The comparison of methane production between different hydrogen concentrations and different carbon sources can indicate which process is most affected by increased hydrogen concentrations. The results from this study were combined with a newly formulated steady-state model of propionate degradation and formation of methane, that also accounts for the venting off both gases via plants. The resulting model indicates how methane production and emissions would be affected by plant volatilization.

  11. NMR Evidence of Cage-to-Cage Diffusion of H2 in H2-Clathrates

    NASA Astrophysics Data System (ADS)

    Senadheera, Lasitha; Conradi, Mark

    2008-03-01

    H2 and heavy-ice at P>1 kbar and T ˜250 K form H2-D2O clathrate; four and one H2 may occupy each large (L) and small (S) cage, respectively. In H2-THF-H2O clathrate, H2 occupies singly and only S cages. Previous electronic-structure calculations estimate the barriers for H2 passage though hexagonal and pentagonal faces of cages as ˜6 and ˜25 kcal/mol, respectively. Our H2 NMR linewidth data reflect random crystal fields from frozen cage-wall D2O orientations. We find dramatic reductions in linewidth starting at 120 K (175 K) for H2-D2O (H2-TDF-D2O) indicating time-averaging of the crystal fields. Assuming Arrhenius behavior, our data imply energies for escape from L (S) cages of about ˜4 (˜6) kcal/mol. For L cages, the agreement with the calculated (cages were treated as rigid) barrier is reasonable. For H2 in S cages, in H2-TDF-D2O, the extreme disagreement with theory points to another mechanism of time-averaging, reorientations of the cage-wall D2O molecules, as suggested by previous work in TDH-H2O clathrate. Our limited NMR spectra at high T ˜145 K in H2-D2O show evidence of distinct resonances from diffusionally mobile and immobile H2 molecules, as expected.

  12. Alcohol and aldehyde dehydrogenase from Saccharomyces cerevisiae: specific activity and influence on the production of acetic acid, ethanol and higher alcohols in the first 48 h of fermentation of grape must.

    PubMed

    Millán, C; Mauricio, J C; Ortega, J M

    1990-01-01

    The changes in the specific activity of alcohol dehydrogenase (ADH-I and ADH-II) and aldehyde dehydrogenases [AIDH-NADP+ and AIDH-NAD(P)+] from Saccharomyces cerevisiae during the first 48 h of fermentation of grape must were investigated. The biosynthesis of ADH-I and AIDH-NADP+ took place basically during the adaptation of the yeasts to the must (first 4 h), while that of ADH-II occurred immediately after exponential growth (after 12 h). From the products produced by the yeast, only the specific rate of production of ethanol was found to be directly related to the specific activity of ADH-I.

  13. Kinetic Model for UV/H2O2 Degradation of 5-Methoxypsoralen

    NASA Astrophysics Data System (ADS)

    Tchaikovskaya, O. N.; Bryantseva, N. G.; Carrasco, J. L. Gómez; Krayukhina, V. S.; Almagro, M. D. Murcia; Gómez, M. Gómez

    2016-08-01

    The influence of H2O2 on the photodegradataion of 5-methoxypsoralen (5-MOP) in ethanol and in waterethanol solutions upon exposure to KrCl excilamp radiation (λrad = 222 nm) and XeBr excilamp radiation (λrad = 283 nm) is investigated. A kinematic model of photodegradation of the investigated molecule is constructed. The addition of H2O2 resulted in a weak increase of the decay rate of 5-MOP in ethanol exposed to KrCl excilamp radiation. In water-ethanol solutions the addition of H2O2 altered the mechanism of decay of 5-MOP irradiated by the KrCl excilamp in comparison with irradiation by the XeBr excilamp. It has been shown that upon exposure to XeBr excilamp radiation in the presence of H2O2, the primary photoproduct of the transformation of 5-MOP in the reaction corresponding to the first-order kinetic model is formed both in ethanol and in the water-ethanol solutions. Maximum removal of 5-MOP takes place for the ratio of initial concentrations [5-MOP]:[H2O2] = 1:3 after 60 min irradiation. It is found that irradiation by the XeBr excilamp the decay rate of 5-MOP is 5 times higher in the water-ethanol solutions in comparison with ethanol. Upon exposure to KrCl excilamp radiation the mechanism of 5-MOP decay corresponds to a pseudo-firstorder kinetic model. The nature of the dependence of the decay rate of 5-MOP on the irradiation time for the ratio of initial concentrations [5-MOP]:[H2O2] = 1:24 indicates that during decay of the initial compound a photoproduct appears in the system which decays during the irradiation time into secondary compounds. Efficient removal of 5-MOP under this irradiation takes place for the ratio of initial concentrations [5-MOP]:[H2O2] = 1:10 after 60 min irradiation.

  14. Oxidation of ethanol in the rat brain and effects associated with chronic ethanol exposure.

    PubMed

    Wang, Jie; Du, Hongying; Jiang, Lihong; Ma, Xiaoxian; de Graaf, Robin A; Behar, Kevin L; Mason, Graeme F

    2013-08-27

    It has been reported that chronic and acute alcohol exposure decreases cerebral glucose metabolism and increases acetate oxidation. However, it remains unknown how much ethanol the living brain can oxidize directly and whether such a process would be affected by alcohol exposure. The questions have implications for reward, oxidative damage, and long-term adaptation to drinking. One group of adult male Sprague-Dawley rats was treated with ethanol vapor and the other given room air. After 3 wk the rats received i.v. [2-(13)C]ethanol and [1, 2-(13)C2]acetate for 2 h, and then the brain was fixed, removed, and divided into neocortex and subcortical tissues for measurement of (13)C isotopic labeling of glutamate and glutamine by magnetic resonance spectroscopy. Ethanol oxidation was seen to occur both in the cortex and the subcortex. In ethanol-naïve rats, cortical oxidation of ethanol occurred at rates of 0.017 ± 0.002 µmol/min/g in astroglia and 0.014 ± 0.003 µmol/min/g in neurons, and chronic alcohol exposure increased the astroglial ethanol oxidation to 0.028 ± 0.002 µmol/min/g (P = 0.001) with an insignificant effect on neuronal ethanol oxidation. Compared with published rates of overall oxidative metabolism in astroglia and neurons, ethanol provided 12.3 ± 1.4% of cortical astroglial oxidation in ethanol-naïve rats and 20.2 ± 1.5% in ethanol-treated rats. For cortical astroglia and neurons combined, the ethanol oxidation for naïve and treated rats was 3.2 ± 0.3% and 3.8 ± 0.2% of total oxidation, respectively. (13)C labeling from subcortical oxidation of ethanol was similar to that seen in cortex but was not affected by chronic ethanol exposure.

  15. H2AFJ — EDRN Public Portal

    Cancer.gov

    H2AFJ is a core component of the nucleosome. The nucleosome is a histone octamer containing two molecules each of H2A, H2B, H3 and H4 assembled in one H3-H4 heterotetramer and two H2A-H2B heterodimers. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template (the octamer wraps approximately 147 bp of DNA). Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling.

  16. Enhanced H2 Production and Redirected Metabolic Flux via Overexpression of fhlA and pncB in Klebsiella HQ-3 Strain.

    PubMed

    Jawed, Muhammad; Pi, Jian; Xu, Li; Zhang, Houjin; Hakeem, Abdul; Yan, Yunjun

    2016-03-01

    Genetic modifications are considered as one of the most important technologies for improving fermentative hydrogen yield. Herein, we overexpress fhlA and pncB genes from Klebsiella HQ-3 independently to enhance hydrogen molar yield. HQ-3-fhlA/pncB strain is developed by manipulation of pET28-Pkan/fhlA Kan(r) and pBBR1-MCS5/pncB Gm(r) as expression vectors to examine the synchronous effects of fhlA and pncB. Optimization of anaerobic batch fermentations is achieved and the maximum yield of biohydrogen (1.42 mol H2/mol of glucose) is produced in the range of pH 6.5-7.0 at 33-37 °C. Whole cell H2 yield is increased up to 40 % from HQ-3-fhlA/pncB, as compared with HQ-3-fhlA 20 % and HQ-3-pncB 12 % keeping HQ-3-C as a control. Mechanism of improved H2 yield is studied in combination with metabolic flux analysis by measuring glucose consumption and other metabolites including formate, succinate, 2,3 butanediol, lactate, acetate, ethanol, and hydrogen. The results suggest that under transient conditions, the increase in the total level of NAD by NAPRTase can enhance the rate of NADH-dependent pathways, and therefore, final distribution of metabolites is changed. Combined overexpression of fhlA and pncB eventually modifies the energy and carbon balance leading to enhanced H2 production from FHL as well as by NADH pathway.

  17. Production of Catalyst-Free Hyperpolarised Ethanol Aqueous Solution via Heterogeneous Hydrogenation with Parahydrogen

    NASA Astrophysics Data System (ADS)

    Salnikov, Oleg G.; Kovtunov, Kirill V.; Koptyug, Igor V.

    2015-09-01

    An experimental approach for the production of catalyst-free hyperpolarised ethanol solution in water via heterogeneous hydrogenation of vinyl acetate with parahydrogen and the subsequent hydrolysis of ethyl acetate was demonstrated. For an efficient hydrogenation, liquid vinyl acetate was transferred to the gas phase by parahydrogen bubbling and almost completely converted to ethyl acetate with Rh/TiO2 catalyst. Subsequent dissolution of ethyl acetate gas in water containing OH- ions led to the formation of catalyst- and organic solvent-free hyperpolarised ethanol and sodium acetate. These results represent the first demonstration of catalyst- and organic solvent-free hyperpolarised ethanol production achieved by heterogeneous hydrogenation of vinyl acetate vapour with parahydrogen and the subsequent ethyl acetate hydrolysis.

  18. Synthesis, characterization and biological activities of metal(II) dipicolinate complexes derived from pyridine-2,6-dicarboxylic acid and 2-(piperazin-1-yl)ethanol

    NASA Astrophysics Data System (ADS)

    Büyükkıdan, Nurgün; Yenikaya, Cengiz; İlkimen, Halil; Karahan, Ceyda; Darcan, Cihan; Korkmaz, Tülin; Süzen, Yasemin

    2015-12-01

    The new water-soluble and air stable compounds (H2ppz)[Co(dipic)2]·6H2O (1), (H2ppz)[Ni(dipic)2]·6H2O (2) and (H2ppz)[Zn(dipic)2]·6H2O (3) were prepared by the reaction of corresponding metal(II) acetates and a proton transfer salt, (H2ppz) (Hdipic)2, (4) of pyridine-2,6-dicarboxylic acid (H2dipic) and 2-(piperazin-1-yl)ethanol (ppz). The compounds 1-3 were characterized by elemental, IR, UV-vis. thermal analyses, magnetic measurement and single crystal X-ray diffraction studies. The molecular structures of the title compounds consist of one 1-(2-hydroxyethyl)piperazine-1,4-diium (H2ppz+2) cation, one bis(pyridine-2,6-dicarboxylate)metal(II) [M(dipic)2]2- anion, and six uncoordinated water molecules. In compounds 1-3 the metal ions coordinate to two oxygen and one nitrogen atoms of two pyridine-2,6-dicarboxylate molecules forming an octahedral environment. Antimicrobial activities against Gram (-) wild type (Escherichia coli and Pseudomonas aeruginosa), Gram (+) wild type (Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus and Bacillus subtilis) and clinical isolate (Morganella morganii, Proteus vulgaris and Enterobacter aeruginosa) were also studied. The results were reported, discussed and compared with the corresponding starting materials ((H2ppz) (Hdipic)2 (4), H2dipic and ppz). MIC (Minimal Inhibition Concentration) values of the newly synthesized compounds were determined as 4000 μg/ml (except B. subtilis and clinical isolate E. aeruginosa, >4000 μg/ml).

  19. Efficient H2 production via Chlamydomonas reinhardtii.

    PubMed

    Esquível, Maria G; Amaro, Helena M; Pinto, Teresa S; Fevereiro, Pedro S; Malcata, F Xavier

    2011-12-01

    Molecular hydrogen (H(2)) obtained from biological sources provides an alternative to bulk chemical processes that is moving towards large-scale, economical generation of clean fuel for automotive engines. This opinion article examines recent improvements in H(2) production by wild and mutant strains of Chlamydomonas reinhardtii - the green microalga currently considered the best eukaryotic H(2) producer. Here, we review various aspects of genetic and metabolic engineering of C. reinhardtii, as well as of process engineering. Additionally, we lay out possible scenarios that would lead to more efficient research approaches in the near future, as part of a consistent strategy for sustainable biohydrogen supply.

  20. Genetic dissection of acetic acid tolerance in Saccharomyces cerevisiae.

    PubMed

    Geng, Peng; Xiao, Yin; Hu, Yun; Sun, Haiye; Xue, Wei; Zhang, Liang; Shi, Gui-Yang

    2016-09-01

    Dissection of the hereditary architecture underlying Saccharomyces cerevisiae tolerance to acetic acid is essential for ethanol fermentation. In this work, a genomics approach was used to dissect hereditary variations in acetic acid tolerance between two phenotypically different strains. A total of 160 segregants derived from these two strains were obtained. Phenotypic analysis indicated that the acetic acid tolerance displayed a normal distribution in these segregants, and suggested that the acetic acid tolerant traits were controlled by multiple quantitative trait loci (QTLs). Thus, 220 SSR markers covering the whole genome were used to detect QTLs of acetic acid tolerant traits. As a result, three QTLs were located on chromosomes 9, 12, and 16, respectively, which explained 38.8-65.9 % of the range of phenotypic variation. Furthermore, twelve genes of the candidates fell into the three QTL regions by integrating the QTL analysis with candidates of acetic acid tolerant genes. These results provided a novel avenue to obtain more robust strains.

  1. Electron ionization of H2O

    NASA Astrophysics Data System (ADS)

    King, Simon J.; Price, Stephen D.

    2008-11-01

    Relative partial ionization cross-sections and precursor-specific relative partial ionization cross-sections for fragment ions formed by electron ionization of H2O have been measured using time-of-flight mass spectrometry coupled with a 2D ion coincidence technique. We report data for the formation of H+, H2+, O2+, O+ and OH+ relative to the formation of H2O+, as a function of ionizing electron energy from 30 to 200 eV. This data includes, for the first time, measurements on the formation all positive ion pairs and ion triples by dissociative multiple electron ionization of H2O. Through determinations of the kinetic energy release involved in ion pair formation we provide further evidence that indirect processes contribute significantly to the yield of H+ + OH+ ion pairs below the vertical double ionization threshold.

  2. Super-dissociative recombination of H2+?

    NASA Astrophysics Data System (ADS)

    Mitchell, J. B. A.; Yousif, F. B.; van der Donk, P. J. T.; Morgan, T. J.; Chibisov, M. I.

    1995-11-01

    The dissociative recombination of vibrationally excited H2+ ions to form products in high Rydberg states has been measured. Surprisingly large cross-sections are found for this channel. This seems to be an example of super-dissociative recombination.

  3. H2O Adsorption Kinetics on Smectites

    NASA Technical Reports Server (NTRS)

    Zent, Aaron P.; Howard, J.; Quinn, R. C.

    2000-01-01

    The adsorptive equilibration of H2O with montomorillonite has been measured. At low temperatures and pressures equilibration can require many hours, effectively preventing smectites at the martian surface from responding to diurnal pressure and temperature variations.

  4. TES/Aura L2 Water Vapor (H2O) Limb (TL2H2OL)

    Atmospheric Science Data Center

    2016-10-25

    TES/Aura L2 Water Vapor (H2O) Limb (TL2H2OL) News:  TES News ... Level:  L2 Platform:  TES/Aura L2 Water Vapor Spatial Coverage:  27 x 23 km Limb ... Access: OPeNDAP Parameters:  H2O Water Volume Mixing Radio Precision Vertical Resolution Order ...

  5. Recent Advances in Catalytic Conversion of Ethanol to Chemicals

    SciTech Connect

    Sun, Junming; Wang, Yong

    2014-04-30

    With increased availability and decreased cost, ethanol is potentially a promising platform molecule for the production of a variety of value-added chemicals. In this review, we provide a detailed summary of recent advances in catalytic conversion of ethanol to a wide range of chemicals and fuels. We particularly focus on catalyst advances and fundamental understanding of reaction mechanisms involved in ethanol steam reforming (ESR) to produce hydrogen, ethanol conversion to hydrocarbons ranging from light olefins to longer chain alkenes/alkanes and aromatics, and ethanol conversion to other oxygenates including 1-butanol, acetaldehyde, acetone, diethyl ether, and ethyl acetate.

  6. Enhanced photo-H2 production of R. faecalis RLD-53 by separation of CO2 from reaction system.

    PubMed

    Liu, Bing-Feng; Ren, Nan-Qi; Ding, Jie; Xie, Guo-Jun; Cao, Guang-Li

    2009-02-01

    The effect of different gases, CO(2) concentration, and separation of CO(2) from reaction system on photo-fermentation H(2) production was investigated by batch culture in this study. Experimental results showed that different gases (Ar,N(2),CO(2), and air) as gas phase have obviously affected on photo-H(2) production and a high concentration of CO(2) can inhibit the growth and H(2) evolution of Rhodopseudomonas faecalis RLD-53. When CO(2) concentration at 5%, cell increased most rapidly the specific growth rate of 0.489 g/l/h and the specific growth rate fell to be 0.265 g/l/h when CO(2) concentration at 40%. However, the growth of RLD-53 at CO(2) concentration of 60-100% was almost completely inhibited. At CO(2) concentrations of 5% and 10%, the maximum H(2) yield was 2.54 and 2.59 mol-H(2)/mol acetate, respectively, and it was similar with the control (2.61 mol-H(2)/mol acetate). H(2) not produced when CO(2) concentration at 60-100%. In conclusion, separation of CO(2) from reaction system can stimulate H(2) production in the entire photo-H(2) production process and H(2) yield increased about 12.8-18.85% than the control.

  7. Biological production of ethanol from coal

    SciTech Connect

    Not Available

    1990-01-01

    Previous results have shown that the medium pH, the composition of the medium and concentration of medium constituents significantly affect the ratio of ethanol to acetate in the product stream when fermenting CO, CO{sub 2} and H{sub 2} in synthesis gas to products by Clostridium ljungdahlii. An additional batch study was carried out varying the agitation rate at pH 4, 4.5 and 5.0. It was speculated that increased agitation rates in combination with low pH might result in increased ethanol production while, at the same time, yielding higher cell concentrations which could eventually result in higher ethanol concentrations.

  8. Synthesis and Biological Activity of Manganese (II) Complexes of Phthalic and Isophthalic Acid: X-Ray Crystal Structures of [Mn(ph)(Phen)2(H2O)]· 4H2O, [Mn(Phen)2(H2O)2]2(Isoph)2(Phen)· 12H2O and {[Mn(Isoph)(bipy)]4· 2.75biby}n(phH2 = Phthalic Acid; isoph = Isophthalic Acid; phen = 1,10-Phenanthroline; bipy = 2,2-Bipyridine)

    PubMed Central

    McCann, Malachy; Leon, Vanessa; Geraghty, Majella; McKee, Vickie; Wikaira, Jan

    2000-01-01

    Manganese(II) acetate reacts with phthalic acid (phH2) to give [Mn(ph)]·0.5H2O (1). Reaction of 1 with 1,10-phenanthroline produces [Mn(ph)(phen)]·2H2O (2) and [Mn(ph)(phen)2(H2O)]·4H2O (3). Reaction of isophthalic acid (isophH2) with manganese(II) acetate results in the formation of [Mn(isoph)]·2H2O (4). The addition of the N,N-donor ligands 1,10-phenanthroline or 2,2'-bipyridine to 4 leads to the formation of [Mn2 (isoph)2(phen)3)]·4H2O (5), [(Mn(phen)2(H2O)2]2(isoph)2(phen)·12H2O (6) and {[Mn(isoph)(bipy)]4·2.75 biby}n (7), respectively. Molecular structures of 3, 6 and 7 were determined crystallographically. In 3 the phthalate ligand is bound to the manganese via just one of its carboxylate groups in a monodentate mode with the remaining coordination sites filled by four phenanthroline nitrogen and one water oxygen atoms. In 6 the isophthalates are uncoordinated with the octahedral manganese center ligated by two phenanthrolines and two waters. In 7 the Isophthalate ligands act as bridges resulting in a polymeric structure. One of the carboxylate groups is chelating a single manganese with the other binding two metal centres in a bridging bidentate mode. The phthalate and isophthalate complexes, the metal free ligands and a number of simple manganes salts were each tested for their ability, to inhibit the growth of Candida albicans. Only the “metal free” 1,10-phenanthroline and its manganese complexes were found to be active. PMID:18475957

  9. Novel cooperative interactions and structural ordering in H2S-H2

    SciTech Connect

    Kent, Paul R

    2011-01-01

    Hydrogen sulfide (H2S) and hydrogen (H2) crystallize into a 'guest-host' structure at 3.5 GPa and, at the initial formation pressure, the rotationally disordered component molecules exhibit weak van der Waals type interactions. With increasing pressure, hydrogen bonding develops and strengthens between neighboring H2S molecules, reflected in a pronounced drop in S-H vibrational stretching frequency and also observed in first-principles calculations. At 17 GPa, an ordering process occurs where H2S molecules orient themselves to maximize hydrogen bonding and H2 molecules simultaneously occupy a chemically distinct lattice site. Intermolecular forces in the H2S+H2 system may be tuned with pressure from the weak hydrogen-bonding limit to the ordered hydrogen-bonding regime, resulting in a novel clathrate structure stabilized by cooperative interactions.

  10. Understanding H2- H2 interactions in Metal Organic Frameworks (MOFs) with unsaturated metal centers

    NASA Astrophysics Data System (ADS)

    Nijem, Nour; Veyan, Jean F.; Kong, Lingzhu; Zhao, Yonggang; Li, Jing; Langreth, David; Chabal, Yves J.

    2011-03-01

    Unsaturated Metal Organic Frameworks (MOFs) are particularly interesting due to their high H2 uptakes with relatively large isosteric heats of adsorption (Qst > 8 kJ / mol) . ThisworkexploresH 2 - H 2 interactionsbetweenadsorbedH 2 atthedifferentsitesinMOF - 74 (M 2 (dhtp) , dhtp = 2 , 5 - dihydroxyterephthalate) andcombinesIRspectroscopywithvdW - DFTcalculations . TheadsorptionsitesinMOF - 74 arefromhighesttolowestbindingenergiesthemetal , oxygen , benzeneandpore - centersites . ThefrequencyofadsorbedH 2 atthemetalsitesuffersanadditional ~ - 30 cm -1 redshift (forMgandZn) and ~ - 84 cm -1 (forCo) whentheneighboringoxygensiteisoccupied . ThedipolemomentofadsorbedH 2 isalsoaffected . TheseinteractionsextendtothebenzenesitesforMOF - 74 - Co . AdecreaseindipolemomentofH 2 adsorbedatthemetalsiteisobservedwiththepartialoccupationofthebenzenesites . However , thecompleteoccupationofthebenzenesitesinducesanadditional ~ - 10 cm -1 red shift. DOE Grant No. DE-FG02-08ER46491.

  11. Extractive fermentation of acetic acid

    SciTech Connect

    Busche, R.M.

    1991-12-31

    In this technoeconomic evaluation of the manufacture of acetic acid by fermentation, the use of the bacterium: Acetobacter suboxydans from the old vinegar process was compared with expected performance of the newer Clostridium thermoaceticum bacterium. Both systems were projected to operate as immobilized cells in a continuous, fluidized bed bioreactor, using solvent extraction to recover the product. Acetobacter metabolizes ethanol aerobically to produce acid at 100 g/L in a low pH medium. This ensures that the product is in the form of a concentrated extractable free acid, rather than as an unextractable salt. Unfortunately, yields from glucose by way of the ethanol fermentation are poor, but near the biological limits of the organisms involved. Conversely, C. thermoaceticum is a thermophilic anaerobe that operates at high fermentation rates on glucose at neutral pH to produce acetate salts directly in substantially quantitative yields. However, it is severely inhibited by product, which restricts concentration to a dilute 20 g/L. An improved Acetobacter system operating with recycled cells at 50 g/L appears capable of producing acid at $0.38/lb, as compared with a $0.29/lb price for synthetic acid. However, this system has only a limited margin for process improvement. The present Clostridium system cannot compete, since the required selling price would be $0.42/lb. However, if the organism could be adapted to tolerate higher product concentrations at acid pH, selling price could be reduced to $0.22/lb, or about 80% of the price of synthetic acid.

  12. H2CO in the Horsehead nebula

    NASA Astrophysics Data System (ADS)

    Guzman, Viviana

    2011-07-01

    Photodissociation region (PDR) models are used to understand the evolution of the far-UV illuminated matter both in our Galaxy and in external galaxies. The spectacular instrumental improvements, which happens in radioastronomy with the advent of Herschel, ALMA and NOEMA, call for matching progresses in PDR modeling. While it is now confirmed that some interstellar species are mostly formed in the gas phase (CO for instance) and others on grains (CH3OH, Garrod et al. 2007), the chemical routes for other species, like H2CO, are still debated because it is likely that solid and gas phase processes are both needed. The availability of well defined observations is essential here to discriminate between chemical assumptions about the important grain surface processes: adsorption, desorption and reactivity. Due to its closeness (~400 pc) and simple geometry, the Horsehead PDR is particularly well suited to investigate the grain surface chemistry. We present observations of 7 transitions of formaldehyde (H2CO) toward two positions: the edge of the nebula exposed to the UV-field (PDR), and a colder region (cold core) shielded from the UV radiation. A non-LTE Montecarlo radiative transfer code is used to determine the H2CO abundance from the observed intensities and line profiles. We find that the H2CO abundance is very similar in the warm PDR and in the cold dense core. The inferred abundances are compared with PDR models, including both gas-phase and grain surface reactions, in order to study the dominant formation routes of H2CO. Pure gas-phase chemistry models fail to reproduce the observed H2CO abundance by a factor ~10 in the PDR, while surface grain chemistry increases the H2CO abundance up to 3 orders of magnitude in the PDR.

  13. Hydrogen isotope systematics of H2-H2O-CH4 during hydrogenotrophic methanogenesis

    NASA Astrophysics Data System (ADS)

    Kobayashi, M.; Kawagucci, S.; Hattori, S.; Yamada, K.; Ueno, Y.; Takai, K.; Yoshida, N.

    2011-12-01

    Hydrogen and carbon isotopes of CH4 have been utilized to trace microbial processes. The isotope fractionations during hydrogenotrophic methanogenesis, one of the major processes of environmental CH4, have been studied by several laboratory incubations. For the carbon isotope, H2 concentration is thought to be the major parameter controlling the carbon isotope fractionation by hydrogenotrophic methanogenesis. For the hydrogen, on the other hand, factors controlling isotope fractionation remain poorly understood, although H2 concentration is suggested to be important. This uncertainty prevents us to utilize δD-CH4 value as the tracer. The most important and principal question is whether all hydrogen atoms in microbially-generated CH4 come from environmental H2O or not. To answer the question, we investigated the D/H systematics of H2-H2O-CH4 during hydrogenotrophic methanogenesis by pure culture incubation with softly deuterium-enriched H2 and/or H2O. Our results demonstrate that δD-CH4 value produced by hydrogenotrophic methanogens depends not only on δD-H2O value but also on δD-H2 value. We observed constant correlation between δD-H2 and δD-CH4 values as well as between δD-H2O and δD-CH4 values, which suggests that hydrogen (/deuterium) atom of substrate H2 is also transferred to the product CH4. This implies that the range of δD-CH4 value produced by hydrogenotrophic methanogenesis should be re-evaluated considering the distribution of δD-H2 and δD-H2O values in natural environments.

  14. Rovibrational states of the H2O-H2 complex: An ab initio calculation

    NASA Astrophysics Data System (ADS)

    van der Avoird, Ad; Nesbitt, David J.

    2011-01-01

    All bound rovibrational levels of the H2O-H2 dimer are calculated for total angular momentum J = 0-5 on two recent intermolecular potential surfaces reported by Valiron et al. [J. Chem. Phys. 129, 134306 (2008)] and Hodges et al. [J. Chem. Phys. 120, 710 (2004)] obtained through ab initio calculations. The method used handles correctly the large amplitude internal motions in this complex; it involves a discrete variable representation of the intermolecular distance coordinate R and a basis of coupled free rotor wave functions for the hindered internal rotations and the overall rotation of the dimer. The basis is adapted to the permutation symmetry associated with the para/ortho (p/o) nature of both H2O and H2 as well as to inversion symmetry. Dimers containing oH2 are more strongly bound than dimers with pH2, as expected, with dissociation energies D_0 of 33.57, 36.63, 53.60, and 59.04 cm^{-1}for pH2O-pH2, oH2O-pH2, pH2O-oH2, and oH2O-oH2, respectively, on the potential of Valiron et al. that corresponds to a binding energy D_e of 235.14 cm^{-1}. Rovibrational wave functions are computed as well and the nature of the bound states in the four different dimer species is discussed. Converged rovibrational levels on both potentials agree well with the high-resolution spectrum reported by Weida and Nesbitt [J. Chem. Phys. 110, 156 (1999)]; the hindered internal rotor model that was used to interpret this spectrum is qualitatively correct.

  15. Rovibrational states of the H2O-H2 complex: an ab initio calculation.

    PubMed

    van der Avoird, Ad; Nesbitt, David J

    2011-01-28

    All bound rovibrational levels of the H(2)O-H(2) dimer are calculated for total angular momentum J = 0-5 on two recent intermolecular potential surfaces reported by Valiron et al. [J. Chem. Phys. 129, 134306 (2008)] and Hodges et al. [J. Chem. Phys. 120, 710 (2004)] obtained through ab initio calculations. The method used handles correctly the large amplitude internal motions in this complex; it involves a discrete variable representation of the intermolecular distance coordinate R and a basis of coupled free rotor wave functions for the hindered internal rotations and the overall rotation of the dimer. The basis is adapted to the permutation symmetry associated with the para/ortho (p/o) nature of both H(2)O and H(2) as well as to inversion symmetry. Dimers containing oH(2) are more strongly bound than dimers with pH(2), as expected, with dissociation energies D(0) of 33.57, 36.63, 53.60, and 59.04 cm(-1)for pH(2)O-pH(2), oH(2)O-pH(2), pH(2)O-oH(2), and oH(2)O-oH(2), respectively, on the potential of Valiron et al. that corresponds to a binding energy D(e) of 235.14 cm(-1). Rovibrational wave functions are computed as well and the nature of the bound states in the four different dimer species is discussed. Converged rovibrational levels on both potentials agree well with the high-resolution spectrum reported by Weida and Nesbitt [J. Chem. Phys. 110, 156 (1999)]; the hindered internal rotor model that was used to interpret this spectrum is qualitatively correct.

  16. Interstellar H2 toward HD 147888

    NASA Astrophysics Data System (ADS)

    Gnaciński, P.

    2013-01-01

    The ultraviolet and far-ultraviolet spectra of HD 147888 allows the H2 vibrational level ν = 0 to be accessed along with higher vibrational levels of the ground H2 electronic level. The large number of H2 absorption lines in the HST spectra allows column densities to be determined even from a noisy spectra. We have determined column densities of the H2 molecule on vibrational levels ν = 0-5 and rotational levels J = 0-6 using the profile fitting method. No variations in the column densities of H2 on vibrationally excited levels were observed from 2000 through 2009. The ortho to para H2 ratio (O/P)* for the excited vibrational states ν = 1-4 equals to 1.13. For the lowest vibrational state ν = 0 and rotational level J = 1 the ortho to para H2 ratio is only 0.15. The temperature of ortho-para thermodynamical equilibrium is TOP = 42 ± 3 K. The measurements of H2 column densities on excited vibrational levels (from the HST spectra) leads to constraints on the radiation field in photon-dominated region (PDR) models of the interstellar cloud towards HD 147888. The Meudon PDR model locates the cloud 0.62 pc from the star. The modeled hydrogen cloud density (89-336 cm-3) agrees with independent density estimations based on the C2 molecule and the chemical model. The observed (O/P)J = 1 and (O/P)* H2 ratios cannot be explained by a simple model. Based on observations made with the NASA/ESA Hubble Space Telescope and with NASA/Johns Hopkins University Far Ultraviolet Spectroscopic Explorer, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. Support for FUSE data is provided by the NASA Office of Space Science via grant NAG5-7584 and by other grants and contracts.

  17. Percutaneous Sclerotherapy Using Acetic Acid After Failure of Alcohol Ablation in an Intra-abdominal Lymphangioma

    SciTech Connect

    Park, Sang Woo Cha, In Ho; Kim, Kyeong Ah; Hong, Suk Joo; Park, Cheol Min; Chung, Hwan Hoon

    2004-09-15

    We report a case of percutaneous sclerotherapy using acetic acid in a 22-year-old woman with an intra-abdominal cystic lymphangioma who was not successfully treated with ethanol despite multiple trials.

  18. H_2CO in the Horsehead nebula

    NASA Astrophysics Data System (ADS)

    Guzman, V.; Pety, J.; Goicoechea, J. R.; Gerin, M.; Roueff, E.

    2011-05-01

    Photodissociation region (PDR) models are used to understand the evolution of the far-UV illuminated matter both in our Galaxy and in external galaxies. The spectacular instrumental improvements, which happens in radioastronomy with the advent of Herschel, ALMA and NOEMA, call for matching progresses in PDR modeling. While it is now confirmed that some interstellar species are mostly formed in the gas phase (CO for instance) and others on grains (CH_3OH), the chemical routes for other species, like H_2CO, are still debated because it is likely that solid and gas phase processes are both needed. The availability of well defined observations is essential here to discriminate between chemical assumptions about the important grain surface processes: adsorption, desorption and reactivity. Due to its closeness (~400 pc) and simple geometry, the Horsehead PDR is particularly well suited to investigate the grain surface chemistry. We present observations of 7 transitions of formaldehyde (H_2CO) toward two positions: the edge of the nebula exposed to the UV-field (PDR), and a colder region (cold core) shielded from the UV radiation. A non-LTE Montecarlo radiative transfer code is used to determine the H2CO abundance from the observed intensities and line profiles. We find that the H_2CO abundance is very similar in the warm PDR and in the cold dense core. The inferred abundances are compared with PDR models, including both gas-phase and grain surface reactions, in order to study the dominant formation routes of H_2CO. Pure gas-phase chemistry models fail to reproduce the observed H2CO abundance by a factor ~10 in the PDR, while surface grain chemistry successfully reproduces the observed abundance.

  19. Possible sources of H2 to H2O enrichment at evaporation of parent chondritic material

    NASA Technical Reports Server (NTRS)

    Makalkin, A. B.; Dorofeyeva, V. A.; Vityazev, A. V.

    1993-01-01

    One of the results obtained from thermodynamic simulation of recondensation of the source chondritic material is that at 1500-1800 K it's possible to form iron-rich olivine by reaction between enstatite, metallic iron and water vapor in the case of (H2O)/(H2) approximately equal to 0.1. This could be reached if the gas depletion in hydrogen is 200-300 times relative to solar abundance. To get this range of depletion one needs some source material more rich in hydrogen than the carbonaceous CI material which is the richest in volatiles among chondrites. In the case of recondensation at impact heating and evaporation of colliding planetesimals composed of CI material, we obtain insufficiently high value of (H2)/(H2O) ratio. In the present paper we consider some possible source materials and physical conditions necessary to reach gas composition with (H2)/(H2O) approximately 10 at high temperature.

  20. VUV photoionization cross sections of HO2, H2O2, and H2CO.

    PubMed

    Dodson, Leah G; Shen, Linhan; Savee, John D; Eddingsaas, Nathan C; Welz, Oliver; Taatjes, Craig A; Osborn, David L; Sander, Stanley P; Okumura, Mitchio

    2015-02-26

    The absolute vacuum ultraviolet (VUV) photoionization spectra of the hydroperoxyl radical (HO2), hydrogen peroxide (H2O2), and formaldehyde (H2CO) have been measured from their first ionization thresholds to 12.008 eV. HO2, H2O2, and H2CO were generated from the oxidation of methanol initiated by pulsed-laser-photolysis of Cl2 in a low-pressure slow flow reactor. Reactants, intermediates, and products were detected by time-resolved multiplexed synchrotron photoionization mass spectrometry. Absolute concentrations were obtained from the time-dependent photoion signals by modeling the kinetics of the methanol oxidation chemistry. Photoionization cross sections were determined at several photon energies relative to the cross section of methanol, which was in turn determined relative to that of propene. These measurements were used to place relative photoionization spectra of HO2, H2O2, and H2CO on an absolute scale, resulting in absolute photoionization spectra.

  1. TES/Aura L2 Water Vapor (H2O) Limb (TL2H2OLS)

    Atmospheric Science Data Center

    2016-10-25

    TES/Aura L2 Water Vapor (H2O) Limb (TL2H2OLS) News:  TES News ... Level:  L2 Platform:  TES/Aura L2 Water Vapor Spatial Coverage:  27 x 23 km Limb ... Access:  OPeNDAP Parameters:  H2O Water Volume Mixing Radio Precision Vertical Resolution Order ...

  2. Methods for increasing the production of ethanol from microbial fermentation

    DOEpatents

    Gaddy, James L.; Arora, Dinesh K.; Ko, Ching-Whan; Phillips, John Randall; Basu, Rahul; Wikstrom, Carl V.; Clausen, Edgar C.

    2007-10-23

    A stable continuous method for producing ethanol from the anaerobic bacterial fermentation of a gaseous substrate containing at least one reducing gas involves culturing a fermentation bioreactor anaerobic, acetogenic bacteria in a liquid nutrient medium; supplying the gaseous substrate to the bioreactor; and manipulating the bacteria in the bioreactor by reducing the redox potential, or increasing the NAD(P)H TO NAD(P) ratio, in the fermentation broth after the bacteria achieves a steady state and stable cell concentration in the bioreactor. The free acetic acid concentration in the bioreactor is maintained at less than 5 g/L free acid. This method allows ethanol to be produced in the fermentation broth in the bioreactor at a productivity greater than 10 g/L per day. Both ethanol and acetate are produced in a ratio of ethanol to acetate ranging from 1:1 to 20:1.

  3. Search for H2COH+ and H2(13)CO in dense interstellar molecular clouds

    NASA Technical Reports Server (NTRS)

    Minh, Y. C.; Irvine, W. M.; McGonagle, D.

    1993-01-01

    We have searched for the 2 mm transitions of H2COH+ (2(02) - 1(01)) and H2(13)CO (2(02) - 1(01), 2(12) - 1(11), and 2(11) - 1(10)) toward the dense interstellar molecular clouds Orion A, TMC-1 and L134N using the FCRAO 14m telescope. None of the transitions have been detected except the H2(13)CO transitions toward Orion-KL. We set upper limits for the abundances of the protonated formaldehyde ion (H2COH+), which are close to the abundances expected from ion-molecule chemistry.

  4. 42 CFR 52h.2 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS SCIENTIFIC PEER REVIEW OF RESEARCH GRANT APPLICATIONS AND RESEARCH AND DEVELOPMENT CONTRACT PROJECTS § 52h.2 Definitions. As used in this... request for proposals. (g) Development means the systematic use of knowledge gained from research...

  5. Advanced Colloids Experiment (ACE-H-2)

    NASA Technical Reports Server (NTRS)

    Meyer, William V.; Sicker, Ron; Chmiel, Alan J.; Eustace, John; LaBarbera, Melissa

    2015-01-01

    Increment 43 - 44 Science Symposium presentation of Advanced Colloids Experiment (ACE-H-2) to RPO. The purpose of this event is for Principal Investigators to present their science objectives, testing approach, and measurement methods to agency scientists, managers, and other investigators.

  6. H2O Adsorption Kinetics on Smectites

    NASA Technical Reports Server (NTRS)

    Zent, Aaron P.; Quinn, Richard C.; Howard, Jeanie; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The adsorptive equilibration of H2O a with montomorillonite, a smectite clay has been measured. At low temperatures and pressures, equilibration can require many hours, effectively preventing smectites at the martian surface from responding rapidly to diurnal pressure and temperature variations.

  7. EPA H2O Software Tool

    EPA Science Inventory

    EPA H2O allows user to: Understand the significance of EGS in Tampa Bay watershed; visually analyze spatial distribution of the EGS in Tampa Bay watershed; obtain map and summary statistics of EGS values in Tampa Bay watershed; analyze and compare potential impacts of development...

  8. EPA H2O User Manual

    EPA Science Inventory

    EPA H2O is a software tool designed to support research being conducted in the Tampa Bay watershed to provide information, data, and approaches and guidance that communities can use to examine alternatives when making strategic decisions to support a prosperous and environmentall...

  9. Acetato­aqua­{4,4′,6,6′-tetra-tert-butyl-2,2′-[(2-pyridyl­meth­yl)imino­dimethyl­ene]diphenolato}manganese(III) ethanol solvate

    PubMed Central

    Chard, Elliott; Dawe, Louise N.; Kozak, Christopher M.

    2010-01-01

    In the title complex, [Mn(C36H50N2O2)(CH3COO)(H2O)]·CH3CH2OH, the MnIII atom is in an octa­hedral environment and is coordinated by the tetra­dentate amine–bis­(phenolate) ligand, a monodentate acetate anion and a water mol­ecule. An ethanol solvent mol­ecule is also found in the asymmetric unit. The structure displays O—H⋯O and C—H⋯O hydrogen bonding. PMID:21587701

  10. Selective synthesis of cyclic peroxides from triketones and H2O2.

    PubMed

    Terent'ev, Alexander O; Yaremenko, Ivan A; Chernyshev, Vladimir V; Dembitsky, Valery M; Nikishin, Gennady I

    2012-02-17

    A method for the assembly of tricyclic structures containing the peroxide, monoperoxyacetal, and acetal moieties was developed based on the acid-catalyzed reaction of β,δ-triketones with H(2)O(2). Tricyclic compounds are formed selectively in yields from 39% to 90% by the reactions with the use of large amounts of strong acids, such as H(2)SO(4), HClO(4), or HBF(4), which act both as the catalyst and as the co-solvent. The reaction is unusual in that, despite the diversity of possible peroxidation pathways giving cyclic compounds and oligomers, the reaction proceeds with high selectivity and produces tricyclic peroxides via the monoperoxidation of the carbonyl groups in the β-positions and the transformation of the δ-carbonyl group into the acetal one. The syntheses are scaled up to tens of grams, and the resulting peroxides can be easily isolated from the reaction mixture.

  11. Overexpression of acetyl-CoA synthetase in Saccharomyces cerevisiae increases acetic acid tolerance.

    PubMed

    Ding, Jun; Holzwarth, Garrett; Penner, Michael H; Patton-Vogt, Jana; Bakalinsky, Alan T

    2015-01-01

    Acetic acid-mediated inhibition of the fermentation of lignocellulose-derived sugars impedes development of plant biomass as a source of renewable ethanol. In order to overcome this inhibition, the capacity of Saccharomyces cerevisiae to synthesize acetyl-CoA from acetic acid was increased by overexpressing ACS2 encoding acetyl-coenzyme A synthetase. Overexpression of ACS2 resulted in higher resistance to acetic acid as measured by an increased growth rate and shorter lag phase relative to a wild-type control strain, suggesting that Acs2-mediated consumption of acetic acid during fermentation contributes to acetic acid detoxification.

  12. 20 CFR 655.132 - H-2A labor contractor (H-2ALC) filing requirements.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Application for Temporary Employment Certification the following: (1) The name and location of each fixed-site... employment in which the fixed-site employer(s) to whom an H-2ALC is furnishing employees will be utilizing... dates when the H-2ALC will be providing the workers to each fixed site, and a description of the...

  13. High pressure-temperature Raman spectroscopy of H2-H2O clathrate.

    NASA Astrophysics Data System (ADS)

    Somayazulu, Maddury; Levedahl, Alexander; Goncharov, Alexander; Mao, Ho-Kwang; Hemley, Russell

    2007-03-01

    The melting curve of the C2 clathrate H2-H2O has been determined by in-situ Raman spectroscopy measurements in an externally heated diamond anvil cell. We have determined the melting curve to a maximum pressure of 27 GPa. These are the first measurements on the melting line in this clathrate. Depending on the stoichiometry of the starting mixture of H2 and H2O, we are able to study either a mixture of C2 and H2O or C2 and H2. In either case, we were able to pinpoint the melting of the clathrate from the measurements of the molecular stretching mode (vibron) in the clathrate. In the case of C2 + Ice VII, we observe the vibron in the clathrate at a frequency higher than in pure H2 at the same pressure. We have cross-calibrated the melting temperatures using the Stokes-anti Stokes ratio of the diamond first order and Raman active TO phonon of cubic Boron Nitride. We find that the clathrate melts well above the H2 melting at all pressures studied indicating that the stabilization of this clathrate at high pressures is indeed due to interactions between the host and guest molecules.

  14. Formation of low-temperature cirrus from H2SO4/H2O aerosol droplets.

    PubMed

    Bogdan, A; Molina, M J; Sassen, K; Kulmala, M

    2006-11-23

    We present experimental results obtained with a differential scanning calorimeter (DSC) that indicate the small ice particles in low-temperature cirrus clouds are not completely solid but rather coated with an unfrozen H2SO4/H2O overlayer. Our results provide a new look on the formation, development, and microphysical properties of low-temperature cirrus clouds.

  15. Preparation of vinyl acetate

    DOEpatents

    Tustin, Gerald Charles; Zoeller, Joseph Robert; Depew, Leslie Sharon

    1998-01-01

    This invention pertains to the preparation of vinyl acetate by contacting a mixture of hydrogen and ketene with a heterogeneous catalyst containing a transition metal to produce acetaldehyde, which is then reacted with ketene in the presence of an acid catalyst to produce vinyl acetate.

  16. Preparation of vinyl acetate

    DOEpatents

    Tustin, G.C.; Zoeller, J.R.; Depew, L.S.

    1998-03-24

    This invention pertains to the preparation of vinyl acetate by contacting a mixture of hydrogen and ketene with a heterogeneous catalyst containing a transition metal to produce acetaldehyde, which is then reacted with ketene in the presence of an acid catalyst to produce vinyl acetate.

  17. The Successive H2O Binding Energies for Fe(H2O)n(+)

    NASA Technical Reports Server (NTRS)

    Ricca, Alessandra; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R. (Technical Monitor)

    1994-01-01

    The binding energy, computed using density functional theory (DFT), are in good agreement with experiment. The bonding is electrostatic (charge-dipole) in origin for all systems. The structures are therefore determined mostly by metal-ligand and ligand-ligand repulsion. The computed structure for FeH2O(+) is C(2v) where sp hybridization is important in reducing the Fe-H2O repulsion. Fe(H2O)2(+) has D2d symmetry where sdo hybridization is the primary factor leading to the linear O-Fe-O geometry. The bonding in Fe(H2O)3(+) and Fe(H2O)4(+) are very complex because ligand-ligand and metal-ligand repulsion, both for the in-plane and out-of-plane water lone-pair orbitals, are important.

  18. Antidepressant Effect of Aminophylline After Ethanol Exposure

    PubMed Central

    Escudeiro, Sarah Souza; Soares, Paula Matias; Almeida, Anália Barbosa; de Freitas Guimarães Lobato, Rodrigo; de Araujo, Dayane Pessoa; Macedo, Danielle Silveira; Sousa, Francisca Cléa Florenço; Patrocínio, Manoel Cláudio Azevedo; Vasconcelos, Silvânia Maria Mendes

    2013-01-01

    This work investigated the association of acute ethanol and aminophylline administration on behavioral models of depression and prefrontal monoamine levels (i.e. norepinephrine and dopamine) in mice. The animals received a single dose of ethanol (2 g/kg) or aminophylline (5 or 10 mg/kg) alone or in association. Thirty minutes after the last drug administration, the animals were assessed in behavioral models by the forced swimming and tail suspension tests. After these tests, the animals were sacrificed and the prefrontal cortices dissected to measure monoamine content. Results showed that ethanol presented depression-like activity in the forced swimming and tail suspension tests. These effects were reversed by the association with aminophylline in all tests. Norepinephrine and dopamine levels decreased, while an increase in the dopamine metabolite, (4-hydroxy-3-methoxyphenyl)acetic acid (DOPAC), after ethanol administration was observed. On the contrary, the association of ethanol and aminophylline increased the norepinephrine and dopamine content, while it decreased DOPAC when compared to the ethanol group, confirming the alterations observed in the behavioral tests. These data reinforce the involvement of the adenosinergic system on ethanol effects, highlighting the importance of the norepinephrine and dopamine pathways in the prefrontal cortex to the effects of ethanol. PMID:23641339

  19. Fuel grade ethanol by solvent extraction: Final subcontract report

    SciTech Connect

    Tedder, D.W.

    1987-04-01

    This report summarizes final results for ethanol recovery by solvent extraction and extractive distillation. At conclusion this work can be summarized as ethanol dehydration and recovery dilute fermentates is feasible using liquid/liquid extraction and extractive distillation. Compared to distillation, the economics are more attractive for less than 5 wt % ethanol. However, an economic bias in favor of SEED appears to exist even for 10 wt % feeds. It is of particular interest to consider the group extraction of ethanol and acetic acid followed by conversion to a mixture of ethanol and ethyl acetate. The latter species is a more valuable commodity and group extraction of inhibitory species is one feature of liquid/liquid extraction that is not easily accomodated using distillation. Upflow immobilized reactors offer the possibility of achieving high substrate conversion while also maintaining low metabolite concentrations. However, many questions remain to be answered with such a concept. 135 refs., 42 figs., 61 tabs.

  20. Enhancement of alcohol-induced hypoglycaemia by H2-receptor antagonists.

    PubMed

    Czyzyk, A; Lao, B; Szutowski, M; Szczepanik, Z; Muszyński, J

    1997-06-01

    The oral ethanol loading test (0.5 g/kg body mass) was carried out in 3 groups with 10 healthy male volunteers each before and after 7 days of administration of either cimetidine (CAS 51481-61-9), ranitidine (CAS 66357-59-3), or famotidine (CAS 76824-35-6). The parameters determined during 6 h comprised the blood levels of ethanol, acetaldehyde, glucose, lactate, pyruvate and bicarbonates, as well as blood pH, PCO2 and PO2. Only ranitidine significantly increased the mean blood ethanol concentration and none of the drugs modified the blood acetaldehyde concentration. Hypoglycaemia following alcohol ingestion was significantly enhanced by all H2-receptor antagonists, but was most pronounced after famotidine. The alcohol-induced rise in blood pyruvate and lactate rather had a tendency to decrease during the second test. The presented results suggest that the evident enhancement of alcohol-induced hypoglycaemia by H2-receptor antagonists is not dependent on the increase of ethanol absorption from the gastrointestinal tract, but represents rather a specific effect of these drugs on glucose metabolism.

  1. Ethanol production during semi-continuous syngas fermentation in a trickle bed reactor using Clostridium ragsdalei.

    PubMed

    Devarapalli, Mamatha; Atiyeh, Hasan K; Phillips, John R; Lewis, Randy S; Huhnke, Raymond L

    2016-06-01

    An efficient syngas fermentation bioreactor provides a mass transfer capability that matches the intrinsic kinetics of the microorganism to obtain high gas conversion efficiency and productivity. In this study, mass transfer and gas utilization efficiencies of a trickle bed reactor during syngas fermentation by Clostridium ragsdalei were evaluated at various gas and liquid flow rates. Fermentations were performed using a syngas mixture of 38% CO, 28.5% CO2, 28.5% H2 and 5% N2, by volume. Results showed that increasing the gas flow rate from 2.3 to 4.6sccm increased the CO uptake rate by 76% and decreased the H2 uptake rate by 51% up to Run R6. Biofilm formation after R6 increased cells activity with over threefold increase in H2 uptake rate. At 1662h, the final ethanol and acetic acid concentrations were 5.7 and 12.3g/L, respectively, at 200ml/min of liquid flow rate and 4.6sccm gas flow rate.

  2. Observations of cumulene carbenes, H2CCCC and H2CCC, in TMC-1

    NASA Technical Reports Server (NTRS)

    Kawaguchi, Kentarou; Kaifu, Norio; Ohishi, Masatoshi; Ishikawa, Shin-Ichi; Hirahara, Yasuhiro; Yamamoto, Satoshi; Saito, Shuji; Takano, Shuro; Murakami, Akinori; Vrtilek, J. M.

    1991-01-01

    Attention is given to the carbon chain molecule H2CCCC, detected in the dark cloud TMC-1 for the first time in the course of a molecular line survey using the Nobeyama 45-m telescope. From nine transitions observed in the frequency region of 17-45 GHz, the total column density of H2CCCC in TMC-1 is derived to be 7.5(+/-2.0) x 10 exp 12/sq cm, which is about half of the value reported in IRC + 10216. Five transitions of a related carbon chain molecule, H2CCC, were also detected in TMC-1. The column density of H2CCC obtained in TMC-1, 2.8(+/-0.9) x 10 exp 12/sq cm, is a factor of three smaller than that of H2CCCC. The ortho-to-para abundance ratios of H2CCCC and H2CCC were found to be 4.2 +/-1.5 and 5.9 +/-2.0, respectively. The chemical reactions of these carbon-chain molecules in dark clouds are discussed.

  3. Biological production of ethanol from coal

    SciTech Connect

    Not Available

    1991-01-01

    Previously studies have shown the importance of both medium composition and concentration and medium pH on ethanol production of Clostridium ljungdahlii in fermenting CO, CO{sub 2} and H{sub 2} in synthesis gas. Four additional batch experiments involving medium composition and concentration were carried out in modified basal medium without yeast extract at pH 4.0. These experiments indicate that basal medium with only small amounts of B-vitamins can yield significant cell growth while yielding ethanol as the major product. Product ratios as high as 11.0 g ethanol per g acetate were obtained with half strength B-vitamins. Further experiments indicates that Ca-pantothenate may be necessary for the growth of C. ljungdahlii and that growth and ethanol production can occur simultaneously.

  4. The H2A.Z/H2B dimer is unstable compared to the dimer containing the major H2A isoform

    PubMed Central

    Placek, Brandon J.; Harrison, L. Nicole; Villers, Brooke M.; Gloss, Lisa M.

    2005-01-01

    The nucleosome, the basic fundamental repeating unit of chromatin, contains two H2A/H2B dimers and an H3/H4 tetramer. Modulation of the structure and dynamics of the nucleosome is an important regulation mechanism of DNA-based chemistries in the eukaryotic cell, such as transcription and replication. One means of altering the properties of the nucleosome is by incorporation of histone variants. To provide insights into how histone variants may impact the thermodynamics of the nucleosome, the stability of the heterodimer between the H2A.Z variant and H2B was determined by urea-induced denaturation, monitored by far-UV circular dichroism, intrinsic Tyr fluorescence intensity, and anisotropy. In the absence of stabilizing agents, the H2A.Z/H2B dimer is only partially folded. The stabilizing cosolute, trimethylamine-N-oxide (TMAO) was used to promote folding of the unstable heterodimer. The equilibrium stability of the H2A.Z/H2B dimer is compared to that of the H2A/H2B dimer. The equilibrium folding of both histone dimers is highly reversible and best described by a two-state model, with no detectable equilibrium intermediates populated. The free energies of unfolding, in the absence of denaturant, of H2A.Z/H2B and H2A/H2B are 7.3 kcal mol−1 and 15.5 kcal mol−1, respectively, in 1 M TMAO. The H2A.Z/H2B dimer is the least stable histone fold characterized to date, while H2A/H2B appears to be the most stable. It is speculated that this difference in stability may contribute to the different biophysical properties of nucleosomes containing the major H2A and the H2A.Z variant. PMID:15632282

  5. The H2A.Z/H2B dimer is unstable compared to the dimer containing the major H2A isoform.

    PubMed

    Placek, Brandon J; Harrison, L Nicole; Villers, Brooke M; Gloss, Lisa M

    2005-02-01

    The nucleosome, the basic fundamental repeating unit of chromatin, contains two H2A/H2B dimers and an H3/H4 tetramer. Modulation of the structure and dynamics of the nucleosome is an important regulation mechanism of DNA-based chemistries in the eukaryotic cell, such as transcription and replication. One means of altering the properties of the nucleosome is by incorporation of histone variants. To provide insights into how histone variants may impact the thermodynamics of the nucleosome, the stability of the heterodimer between the H2A.Z variant and H2B was determined by urea-induced denaturation, monitored by far-UV circular dichroism, intrinsic Tyr fluorescence intensity, and anisotropy. In the absence of stabilizing agents, the H2A.Z/H2B dimer is only partially folded. The stabilizing cosolute, trimethylamine-N-oxide (TMAO) was used to promote folding of the unstable heterodimer. The equilibrium stability of the H2A.Z/H2B dimer is compared to that of the H2A/H2B dimer. The equilibrium folding of both histone dimers is highly reversible and best described by a two-state model, with no detectable equilibrium intermediates populated. The free energies of unfolding, in the absence of denaturant, of H2A.Z/H2B and H2A/H2B are 7.3 kcal mol(-1) and 15.5 kcal mol(-1), respectively, in 1 M TMAO. The H2A.Z/H2B dimer is the least stable histone fold characterized to date, while H2A/H2B appears to be the most stable. It is speculated that this difference in stability may contribute to the different biophysical properties of nucleosomes containing the major H2A and the H2A.Z variant.

  6. Nanofabrication in cellulose acetate.

    PubMed

    Zeng, Hongjun; Lajos, Robert; Metlushko, Vitali; Elzy, Ed; An, Se Young; Sautner, Joshua

    2009-03-07

    We have demonstrated nanofabrication with commercialized cellulose acetate. Cellulose acetate is used for bulk nanofabrication and surface nanofabrication. In bulk nanofabrication, cellulose acetate reacts with an e-beam and permanent patterns are formed in it instead of being transferred to other substrates. We have studied the nano relief modulation performance of cellulose acetate before and after development. The depth of the nanopatterns is magnified after development, and is varied by exposing dosage and line width of the pattern. The thinnest 65 nm wide line is achieved in the bulk fabrication. We also demonstrate a binary phase Fresnel lens array which is directly patterned in a cellulose acetate sheet. Because of its unique mechanical and optical properties, cellulose is a good candidate for a template material for soft imprinting lithography. In the surface nanofabrication, cellulose acetate thin film spin-coated on silicon wafers is employed as a new resist for e-beam lithography. We achieved 50 nm lines with 100 nm pitches, dots 50 nm in diameter, and single lines with the smallest width of 20 nm. As a new resist of e-beam lithography, cellulose acetate has high resolution comparable with conventional resists, while having several advantages such as low cost, long stock time and less harmfulness to human health.

  7. Molecular pathways underpinning ethanol-induced neurodegeneration.

    PubMed

    Goldowitz, Dan; Lussier, Alexandre A; Boyle, Julia K; Wong, Kaelan; Lattimer, Scott L; Dubose, Candis; Lu, Lu; Kobor, Michael S; Hamre, Kristin M

    2014-01-01

    While genetics impacts the type and severity of damage following developmental ethanol exposure, little is currently known about the molecular pathways that mediate these effects. Traditionally, research in this area has used a candidate gene approach and evaluated effects on a gene-by-gene basis. Recent studies, however, have begun to use unbiased approaches and genetic reference populations to evaluate the roles of genotype and epigenetic modifications in phenotypic changes following developmental ethanol exposure, similar to studies that evaluated numerous alcohol-related phenotypes in adults. Here, we present work assessing the role of genetics and chromatin-based alterations in mediating ethanol-induced apoptosis in the developing nervous system. Utilizing the expanded family of BXD recombinant inbred mice, animals were exposed to ethanol at postnatal day 7 via subcutaneous injection (5.0 g/kg in 2 doses). Tissue was collected 7 h after the initial ethanol treatment and analyzed by activated caspase-3 immunostaining to visualize dying cells in the cerebral cortex and hippocampus. In parallel, the levels of two histone modifications relevant to apoptosis, γH2AX and H3K14 acetylation, were examined in the cerebral cortex using protein blot analysis. Activated caspase-3 staining identified marked differences in cell death across brain regions between different mouse strains. Genetic analysis of ethanol susceptibility in the hippocampus led to the identification of a quantitative trait locus on chromosome 12, which mediates, at least in part, strain-specific differential vulnerability to ethanol-induced apoptosis. Furthermore, analysis of chromatin modifications in the cerebral cortex revealed a global increase in γH2AX levels following ethanol exposure, but did not show any change in H3K14 acetylation levels. Together, these findings provide new insights into the molecular mechanisms and genetic contributions underlying ethanol-induced neurodegeneration.

  8. Theoretical study of the rovibrational spectrum of H2O-H2

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Gang; Carrington, Tucker

    2011-01-01

    In this paper we report transition frequencies and line strengths computed for H_2O-H_2 and compare with the experimental observations of [M. J. Weida and D. J. Nesbitt, J. Chem. Phys. 110, 156 (1999)]. To compute the spectra we use a symmetry adapted Lanczos algorithm and an uncoupled product basis set. Our results corroborate the assignments of Weida and Nesbitt and there is good agreement between calculated and observed transitions. Possible candidates for lines that Weida and Nesbitt were not able to assign are presented. Several other bands that may be observable are also discovered. Although all the observed bands are associated with states localized near the global potential minimum, at which H_2O acts as proton acceptor, a state with significant amplitude near the T-shape secondary potential minimum at which H_2O acts as proton donor is identified by examining many different probability density plots.

  9. H2 Production and Fuel Cells

    SciTech Connect

    Wang, Xianqin; Rodriguez, Jose A.

    2007-01-01

    The world demand for energy and the need for protecting our environment can be achieved by increasing energy efficiency and by developing “clean” energy sources. Among the alternative fuels, hydrogen is receiving a lot of attention around the world. In this chapter, recent applications of oxide nanostructures in H2 production and fuel cell technology are summarized. We cover in detail catalytic studies for hydrogen production via the water gas shift reaction over ceria-based nanosystems. These studies illustrate the importance of understanding the fundamental conditions necessary for optimal operation of the catalysts.

  10. A New Parameterization of H2SO4/H2O Aerosol Composition: Atmospheric Implications

    NASA Technical Reports Server (NTRS)

    Tabazadeh, Azadeh; Toon, Owen B.; Clegg, Simon L.; Hamill, Patrick

    1997-01-01

    Recent results from a thermodynamic model of aqueous sulfuric acid are used to derive a new parameterization for the variation of sulfuric acid aerosol composition with temperature and relative humidity. This formulation is valid for relative humidities above 1 % in the temperature range of 185 to 260 K. An expression for calculating the vapor pressure of supercooled liquid water, consistent with the sulfuric acid model, is also presented. We show that the Steele and Hamill [1981] formulation underestimates the water partial pressure over aqueous H2SOI solutions by up to 12% at low temperatures. This difference results in a corresponding underestimate of the H2SO4 concentration in the aerosol by about 6 % of the weight percent at approximately 190 K. In addition, the relation commonly used for estimating the vapor pressure of H2O over supercooled liquid water differs by up to 10 % from our derived expression. The combined error can result in a 20 % underestimation of water activity over a H2SO4 solution droplet in the stratosphere, which has implications for the parameterization of heterogeneous reaction rates in stratospheric sulfuric acid aerosols. The influence of aerosol composition on the rate of homogeneous ice nucleation from a H2SO4 solution droplet is also discussed. This parameterization can also be used for homogeneous gas phase nucleation calculations of H2SO4 solution droplets under various environmental conditions such as in aircraft exhaust or in volcanic plumes.

  11. Refinements in an Mg/MgH2/H2O-Based Hydrogen Generator

    NASA Technical Reports Server (NTRS)

    Kindler, Andrew; Huang, Yuhong

    2010-01-01

    Some refinements have been conceived for a proposed apparatus that would generate hydrogen (for use in a fuel cell) by means of chemical reactions among magnesium, magnesium hydride, and steam. The refinements lie in tailoring spatial and temporal distributions of steam and liquid water so as to obtain greater overall energy-storage or energy-generation efficiency than would otherwise be possible. A description of the prior art is prerequisite to a meaningful description of the present refinements. The hydrogen-generating apparatus in question is one of two versions of what was called the "advanced hydrogen generator" in "Fuel-Cell Power Systems Incorporating Mg-Based H2 Generators" (NPO-43554), NASA Tech Briefs, Vol. 33, No. 1 (January 2009), page 52. To recapitulate: The apparatus would include a reactor vessel that would be initially charged with magnesium hydride. The apparatus would exploit two reactions: The endothermic decomposition reaction MgH2-->Mg + H2, which occurs at a temperature greater than or equal to 300 C, and The exothermic oxidation reaction MgH2 + H2O MgO + 2H2, which occurs at a temperature greater than or equal to 330 C.

  12. Enhancement of atmospheric H2SO4/H2O nucleation: organic oxidation products versus amines

    NASA Astrophysics Data System (ADS)

    Berndt, T.; Sipilä, M.; Stratmann, F.; Petäjä, T.; Vanhanen, J.; Mikkilä, J.; Patokoski, J.; Taipale, R.; Mauldin, R. Lee, III; Kulmala, M.

    2013-06-01

    Atmospheric H2SO4/H2O nucleation influencing effects have been studied in the flow tube IfT-LFT (Institute for Tropospheric Research - Laminar Flow Tube) at 293 ± 0.5 K and a pressure of 1 bar using synthetic air as the carrier gas. The presence of a~possible background amine concentration in the order of 107-108 molecule cm-3 throughout the experiments has to be taken into account. In a first set of investigations, ozonolysis of olefins (tetramethylethylene, 1-methyl-cyclohexene, α-pinene and limonene) for close to atmospheric concentrations, served as the source of OH radicals and possibly other oxidants initiating H2SO4 formation starting from SO2. The oxidant generation is inevitably associated with the formation of a series of organic oxidation products arising from the parent olefins. These products (first generation mainly) showed no clear effect on the number of nucleated particles within a wide range of experimental conditions for H2SO4 concentrations higher than ~107 molecule cm-3. A comparison of the results of two different particle counters (50% cut-off size: about 1.5 nm or 2.5-3 nm) suggested that the early growth process of the nucleated particles was not significantly influenced by the organic oxidation products. An additional, H2SO4-independent process of particle (nano-CN) formation was observed in the case of α-pinene and limonene ozonolysis for H2SO4 concentrations smaller than ~10 7 molecule cm-3. Furthermore, the findings confirm the existence of an additional oxidant for SO2 beside OH radicals, very likely stabilized Criegee Intermediate (sCI). In the case of the ozonolysis of tetramethylethylene, the H2SO4 measurements in the absence and presence of an OH radical scavenger were well described by modelling using recently obtained kinetic data for the sCI reactivity in this system. A second set of experiments has been performed in the presence of added amines (trimethylamine, dimethylamine, aniline and pyridine) in the concentration range

  13. Multiple antibacterial histone H2B proteins are expressed in tissues of American oyster.

    PubMed

    Seo, Jung-Kil; Stephenson, Jeana; Noga, Edward J

    2011-03-01

    We have previously identified a histone H2B isomer (cvH2B-1) from tissue extracts of the bivalve mollusk, the American oyster (Crassostrea virginica). In this paper, we isolate an additional three antibacterial proteins from acidified gill extract by preparative acid-urea-polyacrylamide gel electrophoresis and reversed-phase high performance liquid chromatography. Extraction of these proteins from tissue was best accomplished by briefly boiling the tissues in a weak acetic acid solution. Addition of protease inhibitors while boiling resulted in somewhat lower yields, with one protein being totally absent with this method. Via mass spectrometry, the masses of one of these purified proteins was 13607.0Da (peak 2), which is consistent with the molecular weight of histone H2B. In addition, via western-blotting using anti-calf histone H2B antibody, all three proteins were positive and were thus named cvH2B-2, cvH2B-3 and cvH2B-4. The antibacterial activity of cvH2B-2 was similar to that of cvH2B-1, with activity against a Gram-positive bacterium (Lactococcus lactis subsp. lactis; minimum effective concentration [MEC] 52-57μg/mL) but inactive against Staphylococcus aureus (MEC>250μg/mL). However, both proteins had relatively potent activity against the Gram-negative oyster pathogen Vibrio parahemolyticus (MEC 11.5-14μg/mL) as well as the human pathogen Vibrio vulnificus (MEC 21.3-25.3μg/mL). cvH2B-3 and cvH2B-4 also had similarly strong activity against Vibrio vulnificus. These data provide further evidence for the antimicrobial function of histone H2B isomers in modulating bacterial populations in oyster tissues. The combined estimated concentrations of these histone H2B isomers were far above the inhibitory concentrations for the tested vibrios, including human pathogens. Our results indicate that the highly conserved histone proteins might be important components not only of immune defenses in oysters but have the potential to influence the abundance of a

  14. H2-blocker modulates heart rate variability.

    PubMed

    Ooie, T; Saikawa, T; Hara, M; Ono, H; Seike, M; Sakata, T

    1999-01-01

    The use of H2-blockers in the treatment of patients with peptic ulcer has become popular. However, this treatment has adverse cardiovascular effects. The aim of this study was to investigate proarrhythmic rhythm and autonomic nervous activity by analyzing heart rate variability in patients treated with omeprazole, ranitidine, and plaunotol. Nineteen patients (mean age 67.5 +/- 2.7 years) with active gastric ulcer were treated with omeprazole (20 mg/day) for 8 weeks, then ranitidine (300 mg/day) for the next 4 months, and finally plaunotol (240 mg/day). At each stage of the treatment, Holter electrocardiography was performed, and heart rate variability and arrhythmias analyzed. Heart rate variability yielded power in the low- (0.04-0.15 Hz) and high-frequency components (0.15-0.4 Hz). Although both ranitidine and omeprazole induced little change in cardiac rhythm, the high-frequency power was higher (10.3 +/- 0.8 vs 8.6 +/- 0.6 ms, P < 0.05) and the ratio of low-to-high frequency power was lower (1.41 +/-0.10 vs 1.59 +/- 0.09. P < 0.05) during ranitidine than during plaunotol treatment. Cosinor analysis of heart rate variability revealed a decreased amplitude of low-frequency power during omeprazole compared with during ranitidine and plaunotol treatment. Ranitidine modulated high-frequency power which may be related to the adverse cardiovascular effects of H2-blocker.

  15. Overview on mechanisms of acetic acid resistance in acetic acid bacteria.

    PubMed

    Wang, Bin; Shao, Yanchun; Chen, Fusheng

    2015-02-01

    Acetic acid bacteria (AAB) are a group of gram-negative or gram-variable bacteria which possess an obligate aerobic property with oxygen as the terminal electron acceptor, meanwhile transform ethanol and sugar to corresponding aldehydes, ketones and organic acids. Since the first genus Acetobacter of AAB was established in 1898, 16 AAB genera have been recorded so far. As the main producer of a world-wide condiment, vinegar, AAB have evolved an elegant adaptive system that enables them to survive and produce a high concentration of acetic acid. Some researches and reviews focused on mechanisms of acid resistance in enteric bacteria and made the mechanisms thoroughly understood, while a few investigations did in AAB. As the related technologies with proteome, transcriptome and genome were rapidly developed and applied to AAB research, some plausible mechanisms conferring acetic acid resistance in some AAB strains have been published. In this review, the related mechanisms of AAB against acetic acid with acetic acid assimilation, transportation systems, cell morphology and membrane compositions, adaptation response, and fermentation conditions will be described. Finally, a framework for future research for anti-acid AAB will be provided.

  16. Clean Transformation of Ethanol to Useful Chemicals. The Behavior of a Gold-Modified Silicalite Catalyst.

    PubMed

    Falletta, Ermelinda; Rossi, Michele; Teles, Joaquim Henrique; Della Pina, Cristina

    2016-03-19

    Upon addition of gold to silicalite-1 pellets (a MFI-type zeolite), the vapor phase oxidation of ethanol could be addressed to acetaldehyde or acetic acid formation. By optimizing the catalyst composition and reaction conditions, the conversion of ethanol could be tuned to acetaldehyde with 97% selectivity at 71% conversion or to acetic acid with 78% selectivity at total conversion. Considering that unloaded silicalite-1 was found to catalyze the dehydration of ethanol to diethylether or ethene, a green approach for the integrated production of four important chemicals is herein presented. This is based on renewable ethanol as a reagent and a modular catalytic process.

  17. Biological production of ethanol from coal

    SciTech Connect

    Not Available

    1992-12-01

    Due to the abundant supply of coal in the United States, significant research efforts have occurred over the past 15 years concerning the conversion of coal to liquid fuels. Researchers at the University of Arkansas have concentrated on a biological approach to coal liquefaction, starting with coal-derived synthesis gas as the raw material. Synthesis gas, a mixture of CO, H[sub 2], CO[sub 2], CH[sub 4] and sulfur gases, is first produced using traditional gasification techniques. The CO, CO[sub 2] and H[sub 2] are then converted to ethanol using a bacterial culture of Clostridium 1jungdahlii. Ethanol is the desired product if the resultant product stream is to be used as a liquid fuel. However, under normal operating conditions, the wild strain'' produces acetate in favor of ethanol in conjunction with growth in a 20:1 molar ratio. Research was performed to determine the conditions necessary to maximize not only the ratio of ethanol to acetate, but also to maximize the concentration of ethanol resulting in the product stream.

  18. Traits of selected Clostridium strains for syngas fermentation to ethanol.

    PubMed

    Martin, Michael E; Richter, Hanno; Saha, Surya; Angenent, Largus T

    2016-03-01

    Syngas fermentation is an anaerobic bioprocess that could become industrially relevant as a biorefinery platform for sustainable production of fuels and chemicals. An important prerequisite for commercialization is adequate performance of the biocatalyst (i.e., sufficiently high production rate, titer, selectivity, yield, and stability of the fermentation). Here, we compared the performance of three potential candidate Clostridium strains in syngas-to-ethanol conversion: Clostridium ljungdahlii PETC, C. ljungdahlii ERI-2, and Clostridium autoethanogenum JA1-1. Experiments were conducted in a two-stage, continuously fed syngas-fermentation system that had been optimized for stable ethanol production. The two C. ljungdahlii strains performed similar to each other but different from C. autoethanogenum. When the pH value was lowered from 5.5 to 4.5 to induce solventogenesis, the cell-specific carbon monoxide and hydrogen consumption (similar rate for all strains at pH 5.5), severely decreased in JA1-1, but hardly in PETC and ERI-2. Ethanol production in strains PETC and ERI-2 remained relatively stable while the rate of acetate production decreased, resulting in a high ethanol/acetate ratio, but lower overall productivities. With JA1-1, lowering the pH severely lowered rates of both ethanol and acetate production; and as a consequence, no pronounced shift to solventogenesis was observed. The highest overall ethanol production rate of 0.301 g · L(-1)  · h(-1) was achieved with PETC at pH 4.5 with a corresponding 19 g/L (1.9% w/v) ethanol concentration and a 5.5:1 ethanol/acetate molar ratio. A comparison of the genes relevant for ethanol metabolism revealed differences between C. ljungdahlii and C. autoethanogenum that, however, did not conclusively explain the different phenotypes.

  19. Fate of H2 in an upflow single-chamber microbial electrolysis cell using a metal-catalyst-free cathode.

    PubMed

    Lee, Hyung-Sool; Torres, César I; Parameswaran, Prathap; Rittmann, Bruce E

    2009-10-15

    With the goal of maximizing the H2-harvesting efficiency, we designed an upflow single-chamber microbial electrolysis cell (MEC) by placing the cathode on the top of the MEC and carried out a program to track the fate of H2 and electron equivalents in batch experiments. When the initial acetate concentration was 10 mM in batch-evaluation experiments lasting 32 h, the cathodic conversion efficiency (CCE) from coulombs (i.e., electron equivalents in current from the anode to the cathode) to H2 was 98 +/- 2%, the Coulombic efficiency (CE) was 60 +/- 1%, the H2 yield was 59 +/- 2%, and methane production was negligible. However, longer batch reaction time (approximately 7 days) associated with higher initial acetate concentrations (30 or 80 mM) led to significant H2 loss due to CH4 accumulation: up to 14 +/- 1% and 16 +/- 2% of the biogas at 30 and 80 mM of acetate, respectively. Quantitative PCR proved that no acetoclastic methanogens were present, but that hydrogenotrophic methanogens (i.e., Methanobacteriales) were present on both electrodes. The hydrogenotrophic methanogens decreased the CCE by diverting H2 generated at the cathode to CH4 in the upflow single-chamber MEC. In some experiments, the CE was greater than 100%. The cause was anode-respiring bacteria oxidizing H2 and producing current which recycled H2 between the cathode and the anodes, increasing CE to over 100%, but with a concomitant decline in CCE, despite negligible CH4 formation.

  20. Analysis of trickle-bed reactor for ethanol production from syngas using Clostridium ragsdalei

    NASA Astrophysics Data System (ADS)

    Devarapalli, Mamatha

    The conversion of syngas components (CO, CO2 and H2) to liquid fuels such as ethanol involves complex biochemical reactions catalyzed by a group of acetogens such as Clostridium ljungdahlii, Clostridium carboxidivorans and Clostridium ragsdalei. The low ethanol productivity in this process is associated with the low solubility of gaseous substrates CO and H2 in the fermentation medium. In the present study, a 1-L trickle-bed reactor (TBR) was analyzed to understand its capabilities to improve the mass transfer of syngas in fermentation medium. Further, semi-continuous and continuous syngas fermentations were performed using C. ragsdalei to evaluate the ability of the TBR for ethanol production. In the mass transfer studies, using 6-mm glass beads, it was found that the overall mass transfer coefficient (kLa/V L) increased with the increase in gas flow rate from 5.5 to 130.5 sccm. Further, an increase in the liquid flow rate in the TBR decreased the kLa/VL due to the increase in liquid hold up volume (VL) in the packing. The highest kLa/VL values of 421 h-1 and 178 h-1 were achieved at a gas flow rate of 130.5 sccm for 6-mm and 3-mm glass beads, respectively. Semi-continuous fermentations were performed with repetitive medium replacement in counter-current and co-current modes. In semi-continuous fermentations with syngas consisting of 38% CO, 5% N2, 28.5% CO2 and 28.5% H2 (by volume), the increase in H2 conversion (from 18 to 55%) and uptake (from 0.7 to 2.2 mmol/h) were observed. This increase was attributed to more cell attachment in the packing that reduced CO inhibition to hydrogenase along the column length and increased the H2 uptake. The maximum ethanol produced during counter-current and co-current modes were 3.0 g/L and 5.7 g/L, respectively. In continuous syngas fermentation, the TBR was operated at dilution rates between 0.006 h-1and 0.012 h -1 and gas flow rates between 1.5 sccm and 18.9 sccm. The highest ethanol concentration of 13 g/L was achieved at

  1. Association reactions at low pressure. III. The C2H2+/C2H2 system.

    PubMed

    Anicich, V G; Sen, A D; Huntress, W T; McEwan, M J

    1990-11-15

    The association reactions, C4H2(+) + C2H2 and C4H3(+) + C2H2 have been examined at pressures between 8 x 10(-8) and 1 x 10(-4) Torr at 298 K in an ion cyclotron resonance mass spectrometer. Association occurred via two different mechanisms. At pressures below approximately 2 x 10(-6) Torr, the association was bimolecular having rate coefficients k2 = 2.7 x 10(-10) cm3 s-1 and 2.0 x 10(-10) cm3 s-1 for C4H2+ and C4H3+, respectively. At pressures above approximately 2 x 10(-6) Torr, termolecular association was observed with rate coefficients, k3 = 5.7 x 10(-23) cm6 s-1 and 1.3 x 10(-23) cm6 s-1 for C4H2+ and C4H3+, respectively, when M = C2H2. The termolecular rate constants with N2, Ar, Ne, and He as the third body, M, are also reported. We propose that the low pressure bimolecular association process was the result of radiative stabilization of the complex and the termolecular association process was the result of collisional stabilization. Elementary rate coefficients were obtained and the lifetime of the collision complex was > or = 57 microseconds for (C6H4+)* and > or = 18 microseconds for (C6H5+)*. At pressures below 1 x 10(-6) Torr, approximately 11% of the (C6H4+)* were stabilized by photon emission and the remaining approximately 89% reverted back to reactants, while approximately 24% of the (C6H5+)* were stabilized by photon emission and the remaining approximately 76% reverted back to reactants. The ionic products of the C2H2(+) + C2H2 reaction, C4H2+ and C4H3+, were found to be formed with enough internal energy that they did not react by the radiative association channel until relaxed by several nonreactive collisions with the bath gas.

  2. Quasiclassical trajectory study of formaldehyde unimolecular dissociation: H2CO→H2+CO, H +HCO

    NASA Astrophysics Data System (ADS)

    Zhang, Xiubin; Rheinecker, Jaime L.; Bowman, Joel M.

    2005-03-01

    We report quasiclassical trajectory calculations of the dynamics of the two reaction channels of formaldehyde dissociation on a global ab initio potential energy surface: the molecular channel H2CO→H2+CO and the radical H2CO→H+HCO. For the molecular channel, it is confirmed that above the threshold of the radical channel a second, intramolecular hydrogen abstraction pathway is opened to produce CO with low rotation and vibrationally hot H2. The low-jCO and high-νH2 products from the second pathway increase with the total energy. The competition between the molecular and radical pathways is also studied. It shows that the branching ratio of the molecular products decreases with increasing energy, while the branching ratio of the radical products increases. The results agree well with very recent velocity-map imaging experiments of Suits and co-workers and solves a mystery first posed by Moore and co-workers. For the radical channel, we present the translational energy distributions and HCO rotation distributions at various energies. There is mixed agreement with the experiments of Wittig and co-workers, and this provides an indirect confirmation of their speculation that the triplet surface plays a role in the formation of the radical products.

  3. The H2O2-H2O Hypothesis: Extremophiles Adapted to Conditions on Mars?

    NASA Astrophysics Data System (ADS)

    Houtkooper, Joop M.; Schulze-Makuch, Dirk

    2007-08-01

    The discovery of extremophiles on Earth is a sequence of discoveries of life in environments where it had been deemed impossible a few decades ago. The next frontier may be the Martian surface environment: could life have adapted to this harsh environment? What we learned from terrestrial extremophiles is that life adapts to every available niche where energy, liquid water and organic materials are available so that in principle metabolism and propagation are possible. A feasible adaptation mechanism to the Martian surface environment would be the incorporation of a high concentration of hydrogen peroxide in the intracellular fluid of organisms. The H2O2-H2O hypothesis suggests the existence of Martian organisms that have a mixture of H2O2 and H2O instead of salty water as their intracellular liquid (Houtkooper and Schulze-Makuch, 2007). The advantages are that the freezing point is low (the eutectic freezes at 56.5°C) and that the mixture is hygroscopic. This would enable the organisms to scavenge water from the atmosphere or from the adsorbed layers of water molecules on mineral grains, with H2O2 being also a source of oxygen. Moreover, below its freezing point the H2O2-H2O mixture has the tendency to supercool. Hydrogen peroxide is not unknown to biochemistry on Earth. There are organisms for which H2O2 plays a significant role: the bombardier beetle, Brachinus crepitans, produces a 25% H2O2 solution and, when attacked by a predator, mixes it with a fluid containing hydroquinone and a catalyst, which produces an audible steam explosion and noxious fumes. Another example is Acetobacter peroxidans, which uses H2O2 in its metabolism. H2O2 plays various other roles, such as the mediation of physiological responses such as cell proliferation, differentiation, and migration. Moreover, most eukaryotic cells contain an organelle, the peroxisome, which mediates the reactions involving H2O2. Therefore it is feasible that in the course of evolution, water-based organisms

  4. CO/H2 in Translucent Clouds

    NASA Technical Reports Server (NTRS)

    Green, James

    2005-01-01

    A thorough examination of techniques to improve the resolution of the FUSE spectrograph was undertaken. These involved co-adding time tagged data very carefully so as to remove any blurs caused by drift. In addition, data was binned by detector pulse height bin (to eliminate any positional vs. gain variations, e.g. "walk"). These techniques only resulted in an extremely modest increase in the spectral resolution, insufficient to allow the CO/H2 studies to be performed. The only remaining potential source of blur was defocus - implying the instrument was never properly focused on orbit. Private discussions with B.G. Anderson of the FUSE team resulted in my learning that this was in fact the case - the slidgrating distance was never optimized on orbit - resulting in a degradation of the peak performance of the instrument. Unfortunately, this was never publicized, even to myself, a member of the instrument tem and the spectrograph designer.

  5. Attosecond photoelectron microscopy of H2+

    NASA Astrophysics Data System (ADS)

    Hu, S. X.; Collins, L. A.; Schneider, B. I.

    2009-08-01

    We present a numerical study of the ultrafast ionization dynamics of H2+ exposed to attosecond extreme ultraviolet (xuv) pulses that goes beyond the Born-Openheimer approximation. The four-dimensional, time-dependent Schrödinger equation was solved using a generalization of the finite-element discrete-variable-representation/real-space-product technique used in our previous calculations to include the dynamical motion of the nuclei. This has enabled us to expose the target to any polarized light at arbitrary angles with respect to the molecular axis. Calculations have been performed at different angles and photon energies ( ℏω=50eV up to 630 eV) to investigate the energy and orientation dependence of the photoionization probability. A strong orientation dependence of the photoionization probability of H2+ was found at a photon energy of ℏω=50eV . At this energy, we found that the ionization probability is three times larger in the perpendicular polarization than in the parallel case. These observations are explained by the different geometric “cross sections” seen by the photoejected electron as it leaves the molecule. This ionization anisotropy vanishes at the higher-photon energy of ℏω≥170eV . When these higher-energy xuv pulses are polarized perpendicular to the internuclear axis, a “double-slit-like” interference pattern is observed. However, we find that the diffraction angle only approaches the classical formula ϕn=sin-1(nλe/R0) , where n is the diffraction order, λe is the released electron wavelength, and R0 is the internuclear distance, when nλe becomes less than 65% of R0 . These results illustrate the possibility of employing attosecond pulses to perform photoelectron microscopy of molecules.

  6. Millimeter Wave Spectra of the Internal Rotation Excited States of (o)H_2-H_2O and (o)H_2-D_2O

    NASA Astrophysics Data System (ADS)

    Harada, K.; Iwasaki, Y.; Giesen, T.; Tanaka, K.

    2013-06-01

    H_2-H_2O is a weakly bound complex and it has a various states according to the internal rotation for both H_2 and H_2O moieties. In our previous study, we have reported the pure rotational transitions of the (o)H_2 complex in the ground H_2O rotational state, 0_{00}(Σ), for both H_2-H_2O and H_2-D_2O, where (o)H_2 (j_{ H2} =1) is rotating perpendicular to the intermolecular axis to give the projection of j_{ H2} to the axis k_{ H2} to be zero (i.e. Σ state). In the present study, we have observed the rotational transitions for the 0_{00} (Π) states in the millimeter-wave region up to 220 GHz, where the (o)H_2 is rotating around the intermolecular axis to give the projection k_{ H2} to be one (i.e. Π state). The center of mass bond lengths derived from the observed rotational constants for 0_{00} (Π) are longer by 5 % than those for 0_{00} (Σ), while force constants for the intermolecular stretching for 0_{00} (Π) derived from centrifugal distortion constants are smaller by 23 % than those for 0_{00} (Σ), suggesting the Π and Σ substates have quite different structures. The recent theoretical calculation indicates that for 0_{00}(Σ), (o)H_2 is bound to the oxygen site of H_2O, while for the 0_{00} (Π) state, (o)H_2 to the hydrogen site of H_2O, and the 0_{00}(Σ) state is by 14 cm^{-1} more stable than the 0_{00} (Π) state. Observed molecular constants for 0_{00}(Σ) and (Π) are consistent with the structures given by the theoretical calculation. We also observed the rotational spectrum in the 1_{01} (Σ) and (Π) states, where Σ and Π correspond to the rotation of H_2O perpendicular and parallel to the intermolecular axis and (o)H_2 is calculated to be bound to the oxygen site of H_2O. The energy difference between the 1_{01} (Σ) and (Π) states will be discussed due to the Criolis interaction between these substates. C. J. Whitham, K. Tanaka, and K. Harada, The 56th OSU Symposium, RD08 (2001). Ad. van der Avoid and D. J. Nesbit, J. Chem. Phys

  7. Generation and characterisation of stable ethanol-tolerant mutants of Saccharomyces cerevisiae.

    PubMed

    Stanley, Dragana; Fraser, Sarah; Chambers, Paul J; Rogers, Peter; Stanley, Grant A

    2010-02-01

    Saccharomyces spp. are widely used for ethanologenic fermentations, however yeast metabolic rate and viability decrease as ethanol accumulates during fermentation, compromising ethanol yield. Improving ethanol tolerance in yeast should, therefore, reduce the impact of ethanol toxicity on fermentation performance. The purpose of the current work was to generate and characterise ethanol-tolerant yeast mutants by subjecting mutagenised and non-mutagenised populations of Saccharomyces cerevisiae W303-1A to adaptive evolution using ethanol stress as a selection pressure. Mutants CM1 (chemically mutagenised) and SM1 (spontaneous) had increased acclimation and growth rates when cultivated in sub-lethal ethanol concentrations, and their survivability in lethal ethanol concentrations was considerably improved compared with the parent strain. The mutants utilised glucose at a higher rate than the parent in the presence of ethanol and an initial glucose concentration of 20 g l(-1). At a glucose concentration of 100 g l(-1), SM1 had the highest glucose utilisation rate in the presence or absence of ethanol. The mutants produced substantially more glycerol than the parent and, although acetate was only detectable in ethanol-stressed cultures, both mutants produced more acetate than the parent. It is suggested that the increased ethanol tolerance of the mutants is due to their elevated glycerol production rates and the potential of this to increase the ratio of oxidised and reduced forms of nicotinamide adenine dinucleotide (NAD(+)/NADH) in an ethanol-compromised cell, stimulating glycolytic activity.

  8. Low energy electron collisions in H2S and H2Se

    NASA Astrophysics Data System (ADS)

    Abouaf, Robert; Teillet-Billy, Dominique

    2008-11-01

    Dissociative electron attachment between 0 and 4 eV has been investigated in hydrogen sulfide and hydrogen selenide with an improved electron resolution (0.040 eV). HS- and HSe- cross-sections versus electron energy present vertical onsets revealing that the potential surfaces of the resonances which are reached around 2 eV are bound. A well-developed and intriguing structure is observed in HS-, S-, HSe- and Se- cross-sections. It could reveal interferences due to an attractive resonance having a lifetime of the order of one vibrational period. The strong similarity between the anion behaviour in H2S and H2Se is in contrast with H2O where no dissociative attachment process occurs in this energy range.

  9. Modified graphitized carbon black as transducing material for reagentless H2O2 and enzyme sensors.

    PubMed

    Razumiene, Julija; Barkauskas, Jurgis; Kubilius, Virgaudas; Meskys, Rolandas; Laurinavicius, Valdas

    2005-10-15

    Direct electron transfer between redox enzymes and electrodes is the basis for the third generation biosensors. We established direct electron transfer between quinohemoprotein alcohol dehydrogenase (PQQ-ADH) and modified carbon black (CBs) electrodes. Furthermore, for the first time, this phenomenon was observed for pyrroloquinoline quinone (PQQ)-dependent glucose dehydrogenase (PQQ-GDH). Reagentless enzyme biosensors suitable for the determination of ethanol, glucose and sensors for hydrogen peroxide were designed using CB electrodes and screen-printing technique. Aiming to create an optimal transducing material for biosensors, a set of CB batches was synthesized using the matrix of Plackett-Burman experimental design. Depending on the obtained surface functional groups as well as the nano-scale carbon structures in CBs batches, the maximal direct electron transfer current of glucose and ethanol biosensors can vary from 20 to 300 nA and from 30 to 6300 nA for glucose and ethanol, respectively. Using modified CB electrodes, an electrocatalytic oxidation of H(2)O(2) takes place at more negative potentials (0.1-0.4V versus Ag/AgCl). Moreover, H(2)O(2) oxidation efficiency depends on the amount and morphology of fine fraction in the modified CBs.

  10. FLYING-WATER Renewables-H2-H2O TERRAFORMING: PERMANENT Drought(s)-Elimination FOREVER!!!

    NASA Astrophysics Data System (ADS)

    Ertl, G.; Alefeld, G.; Youdelis, W.; Radd, H.; Oertle, G.; Siegel, Edward

    2011-03-01

    "H2O H2O everywhere; ne'er a drop to drink"[Coleridge(1798)]; now: "H2 H2 everywhere; STILL ne'er a drop to drink": ONLY H2 (or methane CH4) can be FLYING-WATER(F-W) chemical-rain-in-pipelines Hindenberg-effect (H2-UP;H2O-DOWN): {O/H2O}=[16]/[18] 90 % ; O already in air uphill; NO H2O pumping need! In global-warming driven H2O-starved glacial-melting world, rescue is possible ONLY by Siegel [{3rd Intl. Conf. Alt.-Energy }(1980)-vol.5/p.459!!!] Renewables-H2-H2O purposely flexible versatile agile customizable scaleable retrofitable integrated operating-system. Rosenfeld[Science 315,1396(3/9/2007)]-Biello [Sci.Am.(3/9/2007)] crucial geomorph-ology which ONLY maximal-buoyancy H2 can exploit, to again make "Mountains into Fountains", ``upthrust rocks trapping the clouds to precipitate their rain/snow/H2O'': "terraforming"(and ocean-rebasificaton!!!) Siegel proprietary magnetic-hydrogen-valve (MHV) permits H2 flow in already in-ground dense BCC/ferritic-steels pipelines-network (NO new infrastructure) counters Tromp[Science 300,1740(2003)] dire warning of global-pandemics (cancers/ blindness/famine) Hydrogen-economy CATASTROPHIC H2 ozone-layer destruction sobering cavat to dangerous H2-automotion-economy panacea hype!!!

  11. Ethanol cytotoxic effect on trophoblast cells.

    PubMed

    Clave, S; Joya, X; Salat-Batlle, J; Garcia-Algar, O; Vall, O

    2014-03-03

    Prenatal ethanol exposure may cause both, altered fetal neurodevelopment and impaired placental function. These disturbances can lead to growth retardation, which is one of the most prevalent features in Fetal Alcohol Syndrome (FAS). It is not known whether there is a specific pattern of cytotoxicity caused by ethanol that can be extrapolated to other cell types. The aim of this study was to determine the cytotoxic effects caused by sustained exposure of trophoblast cells to ethanol. The cytotoxic effect of sustained exposure to standard doses of ethanol on an in vitro human trophoblast cell line, JEG3, was examined. Viable cell count by exclusion method, total protein concentration, lactate dehydrogenase (LDH) activity and activation of apoptotic markers (P-H2AX, caspase-3 and PARP-1) were determined. Sustained exposure to ethanol decreased viable cell count and total protein concentration. LDH activity did not increased in exposed cells but apoptotic markers were detected. In addition, there was a dose-dependent relationship between ethanol concentration and apoptotic pathways activation. Sustained ethanol exposure causes cellular cytotoxicity by apoptotic pathways induction as a result of DNA damage. This apoptotic induction may partially explain the altered function of placental cells and the damage previously detected in other tissues.

  12. Starvation-induced cross protection against heat or H2O2 challenge in Escherichia coli.

    PubMed

    Jenkins, D E; Schultz, J E; Matin, A

    1988-09-01

    Glucose- or nitrogen-starved cultures of Escherichia coli exhibited enhanced resistance to heat (57 degrees C) or H2O2 (15 mM) challenge, compared with their exponentially growing counterparts. The degree of resistance increased with the time for which the cells were starved prior to the challenge, with 4 h of starvation providing the maximal protection. Protein synthesis during starvation was essential for these cross protections, since chloramphenicol addition at the onset of starvation prevented the development of thermal or oxidative resistance. Starved cultures also demonstrated stronger thermal and oxidative resistance than did growing cultures adapted to heat, H2O2, or ethanol prior to the heat or H2O2 challenge. Two-dimensional gel electrophoresis of 35S-pulse-labeled proteins showed that subsets of the 30 glucose starvation proteins were also synthesized during heat or H2O2 adaptation; three proteins were common to all three stresses. Most of the common proteins were among the previously identified Pex proteins (J.E. Schultz, G. I. Latter, and A. Matin, J. Bacteriol. 170:3903-3909, 1988), which are independent of cyclic AMP positive control for their induction during starvation. Induction of starvation proteins dependent on cyclic AMP was not important in these cross protections, since a delta cya strain of E. coli K-12 exhibited the same degree of resistance to heat or H2O2 as the wild-type parent did during both growth and starvation.

  13. Phase transition and optoelectronic properties of MgH2

    NASA Astrophysics Data System (ADS)

    Nayak, Vikas; Verma, U. P.

    2016-05-01

    In this article, structural and electronic properties of MgH2 have been studied. The aim behind this study was to find out the ground state crystal structure of MgH2. For the purpose, density functional theory (DFT)-based full-potential linearized augmented plane wave (FP-LAPW) calculations have been performed in three different space groups: P42/mnm (α-MgH2), Pa3 (β-MgH2) and Pbcn (γ-MgH2). It has been found that the ground state structure of MgH2 is α-MgH2. The present study shows that α-MgH2 transforms into γ-MgH2 at a pressure of 0.41 GPa. After further increase in pressure, γ-MgH2 transforms into β-MgH2 at a pressure of 3.67 GPa. The obtained results are in good agreement with previously reported experimental data. In all the studied phases, the behavior of MgH2 is insulating and its optical conductivity is around 6.0 eV. The α-MgH2 and γ-MgH2 are anisotropic materials while β-MgH2 is isotropic in nature.

  14. Modeling Ice Giant Interiors Using Constraints on the H2-H2O Critical Curve

    NASA Astrophysics Data System (ADS)

    Bailey, E.; Stevenson, D. J.

    2015-12-01

    We present a range of models of Uranus and Neptune, taking into account recent experimental data (Bali, 2013) implying the location of the critical curve of the H2-H2O system at pressures up to 2.6 GPa. The models presented satisfy the observed total mass of each planet and the radius at the observed 1-bar pressure level. We assume the existence of three regions at different depths: an outer adiabatic envelope composed predominately of H2 and He, with a helium mass fraction 0.26, a water-rich layer including varied amounts of rock and hydrogen, and a chemically homogeneous rock core. Using measured rotation rates of Uranus and Neptune, and a density profile obtained for each model using constituent equations of state and the assumption of hydrostatic equilibrium, we calculate the gravitational harmonics J2 and J4 for comparison with observed values as an additional constraint. The H2-H2O critical curve provides information about the nature of the boundary between the outer, hydrogen-rich envelope and underlying water-rich layer. The extrapolated critical curve for hydrogen-water mixtures crosses the adiabat of the outer atmospheric shell in these models at two depths, implying a shallow outer region of limited miscibility, an intermediate region between ~90 and 98 percent of the total planet radius within which hydrogen and water can mix in all proportions, and another, deeper region of limited miscibility at less than ~90 percent of the total planet radius. The pressure and temperature of the gaseous adiabatic shell at the depth of the shallowest extent of the water-rich layer determines whether a gradual compositional transition or an ocean surface boundary may exist at depth in these planets. To satisfy the observed J2, the outer extent of the water-rich layer in these models must be located between approximately 80 and 85 percent of the total planet radius, within the deep region of limited H2-H2O miscibility, implying an ocean surface is possible within the

  15. Bacterial communities in thermophilic H2-producing reactors investigated using 16S rRNA 454 pyrosequencing.

    PubMed

    Ratti, Regiane Priscila; Delforno, Tiago Palladino; Okada, Dagoberto Yukio; Varesche, Maria Bernadete Amâncio

    2015-04-01

    In this study, the composition and diversity of the bacterial community in thermophilic H2-producing reactors fed with glucose were investigated using pyrosequencing. The H2-producing experiments in batch were conducted using 0.5 and 2.0 g l(-1) glucose at 550 °C. Under the two conditions, the H2 production and yield were 1.3 and 1.6 mol H2 mol glucose(-1), respectively. Acetic, butyric, iso-butyric, lactic and propionic acids were detected in the two reactors. The increase in substrate concentration favored a high H2 yield. In this reactor, a predominance of acetic and iso-butyric acids, 27.7% and 40%, were measured, respectively. By means of pyrosequencing, a total of 323 and 247 operational taxonomic units were obtained, with a predominance of the phylum Firmicutes (68.73-67.61%) for reactors with 0.5 and 2.0 g l(-1) glucose, respectively. Approximately 40.55% and 62.34% of sequences were affiliated with Thermoanaerobacterium and Thermohydrogenium, microorganisms that produce H2 under thermophilic conditions.

  16. H2O2 space shuttle APU

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A cryogenic H2-O2 auxiliary power unit (APU) was developed and successfully demonstrated. It has potential application as a minimum weight alternate to the space shuttle baseline APU because of its (1) low specific propellant consumption and (2) heat sink capabilities that reduce the amount of expendable evaporants. A reference system was designed with the necessary heat exchangers, combustor, turbine-gearbox, valves, and electronic controls to provide 400 shp to two aircraft hydraulic pumps. Development testing was carried out first on the combustor and control valves. This was followed by development of the control subsystem including the controller, the hydrogen and oxygen control valves, the combustor, and a turbine simulator. The complete APU system was hot tested for 10 hr with ambient and cryogenic propellants. Demonstrated at 95 percent of design power was 2.25 lb/hp-hr. At 10 percent design power, specific propellant consumption was 4 lb/hp-hr with space simulated exhaust and 5.2 lb/hp-hr with ambient exhaust. A 10 percent specific propellant consumption improvement is possible with some seal modifications. It was demonstrated that APU power levels could be changed by several hundred horsepower in less than 100 msec without exceeding allowable turbine inlet temperatures or turbine speed.

  17. H2 arcjet performance mapping program

    NASA Astrophysics Data System (ADS)

    1992-01-01

    Work performed during the period of Mar. 1991 to Jan. 1992 is reviewed. High power H2 arcjets are being considered for electric powered orbit transfer vehicles (EOTV). Mission analyses indicate that the overall arcjet thrust efficiency is very important since increasing the efficiency increases the thrust, and thereby reduces the total trip time for the same power. For example, increasing the thrust efficiency at the same specific impulse from 30 to 40 percent will reduce the trip time by 25 percent. For a 200 day mission, this equates to 50 days, which results in lower ground costs and less time during which the payload is dormant. Arcjet performance levels of 1200 seconds specific impulse (lsp) at 35 to 40 percent efficiency with lifetimes over 1000 hours are needed to support EOTV missions. Because of the potential very high efficiency levels, the objective of this program was to evaluate the ability of a scaled Giannini-style thruster to achieve the performance levels while operating at a reduced nominal power of 10 kW. To meet this objective, a review of past literature was conducted; scaling relationships were developed and applied to establish critical dimensions; a development thruster was designed with the aid of the plasma analysis model KARNAC and finite element thermal modeling; test hardware was fabricated; and a series of performance tests were conducted in RRC's Cell 11 vacuum chamber with its null-balance thrust stand.

  18. Simultaneous production of acetic and gluconic acids by a thermotolerant Acetobacter strain during acetous fermentation in a bioreactor.

    PubMed

    Mounir, Majid; Shafiei, Rasoul; Zarmehrkhorshid, Raziyeh; Hamouda, Allal; Ismaili Alaoui, Mustapha; Thonart, Philippe

    2016-02-01

    The activity of bacterial strains significantly influences the quality and the taste of vinegar. Previous studies of acetic acid bacteria have primarily focused on the ability of bacterial strains to produce high amounts of acetic acid. However, few studies have examined the production of gluconic acid during acetous fermentation at high temperatures. The production of vinegar at high temperatures by two strains of acetic acid bacteria isolated from apple and cactus fruits, namely AF01 and CV01, respectively, was evaluated in this study. The simultaneous production of gluconic and acetic acids was also examined in this study. Biochemical and molecular identification based on a 16s rDNA sequence analysis confirmed that these strains can be classified as Acetobacter pasteurianus. To assess the ability of the isolated strains to grow and produce acetic acid and gluconic acid at high temperatures, a semi-continuous fermentation was performed in a 20-L bioreactor. The two strains abundantly grew at a high temperature (41°C). At the end of the fermentation, the AF01 and CV01 strains yielded acetic acid concentrations of 7.64% (w/v) and 10.08% (w/v), respectively. Interestingly, CV01 was able to simultaneously produce acetic and gluconic acids during acetic fermentation, whereas AF01 mainly produced acetic acid. In addition, CV01 was less sensitive to ethanol depletion during semi-continuous fermentation. Finally, the enzymatic study showed that the two strains exhibited high ADH and ALDH enzyme activity at 38°C compared with the mesophilic reference strain LMG 1632, which was significantly susceptible to thermal inactivation.

  19. Mechanism of H2S Oxidation by the Dissimilatory Perchlorate-Reducing Microorganism Azospira suillum PS

    PubMed Central

    Mehta-Kolte, Misha G.; Loutey, Dana; Wang, Ouwei; Youngblut, Matthew D.; Hubbard, Christopher G.; Wetmore, Kelly M.; Conrad, Mark E.

    2017-01-01

    ABSTRACT The genetic and biochemical basis of perchlorate-dependent H2S oxidation (PSOX) was investigated in the dissimilatory perchlorate-reducing microorganism (DPRM) Azospira suillum PS (PS). Previously, it was shown that all known DPRMs innately oxidize H2S, producing elemental sulfur (So). Although the process involving PSOX is thermodynamically favorable (ΔG°′ = −206 kJ ⋅ mol−1 H2S), the underlying biochemical and genetic mechanisms are currently unknown. Interestingly, H2S is preferentially utilized over physiological electron donors such as lactate or acetate although no growth benefit is obtained from the metabolism. Here, we determined that PSOX is due to a combination of enzymatic and abiotic interactions involving reactive intermediates of perchlorate respiration. Using various approaches, including barcode analysis by sequencing (Bar-seq), transcriptome sequencing (RNA-seq), and proteomics, along with targeted mutagenesis and biochemical characterization, we identified all facets of PSOX in PS. In support of our proposed model, deletion of identified upregulated PS genes traditionally known to be involved in sulfur redox cycling (e.g., Sox, sulfide:quinone reductase [SQR]) showed no defect in PSOX activity. Proteomic analysis revealed differential abundances of a variety of stress response metal efflux pumps and divalent heavy-metal transporter proteins, suggesting a general toxicity response. Furthermore, in vitro biochemical studies demonstrated direct PSOX mediated by purified perchlorate reductase (PcrAB) in the absence of other electron transfer proteins. The results of these studies support a model in which H2S oxidation is mediated by electron transport chain short-circuiting in the periplasmic space where the PcrAB directly oxidizes H2S to So. The biogenically formed reactive intermediates (ClO2− and O2) subsequently react with additional H2S, producing polysulfide and So as end products. PMID:28223460

  20. Identification of H2S3 and H2S produced by 3-mercaptopyruvate sulfurtransferase in the brain.

    PubMed

    Kimura, Yuka; Toyofuku, Yukiko; Koike, Shin; Shibuya, Norihiro; Nagahara, Noriyuki; Lefer, David; Ogasawara, Yuki; Kimura, Hideo

    2015-10-06

    Hydrogen polysulfides (H2Sn) have a higher number of sulfane sulfur atoms than hydrogen sulfide (H2S), which has various physiological roles. We recently found H2Sn in the brain. H2Sn induced some responses previously attributed to H2S but with much greater potency than H2S. However, the number of sulfur atoms in H2Sn and its producing enzyme were unknown. Here, we detected H2S3 and H2S, which were produced from 3-mercaptopyruvate (3 MP) by 3-mercaptopyruvate sulfurtransferase (3MST), in the brain. High performance liquid chromatography with fluorescence detection (LC-FL) and tandem mass spectrometry (LC-MS/MS) analyses showed that H2S3 and H2S were produced from 3 MP in the brain cells of wild-type mice but not 3MST knockout (3MST-KO) mice. Purified recombinant 3MST and lysates of COS cells expressing 3MST produced H2S3 from 3 MP, while those expressing defective 3MST mutants did not. H2S3 was localized in the cytosol of cells. H2S3 was also produced from H2S by 3MST and rhodanese. H2S2 was identified as a minor H2Sn, and 3 MP did not affect the H2S5 level. The present study provides new insights into the physiology of H2S3 and H2S, as well as novel therapeutic targets for diseases in which these molecules are involved.

  1. Effects of Lactobacillus plantarum TWK10-Fermented Soymilk on Deoxycorticosterone Acetate-Salt-Induced Hypertension and Associated Dementia in Rats

    PubMed Central

    Liu, Te-Hua; Chiou, Jiachi; Tsai, Tsung-Yu

    2016-01-01

    Oxidative stress resulting from excessive production of reactive oxygen species is the major mediator of neuronal cell degeneration observed in neurodegenerative diseases, such as Alzheimer’s disease (AD) and vascular dementia (VaD). Additionally, hypertension has been shown to be a positive risk factor for VaD. Therefore, the objective of this study was to investigate the effects of Lactobacillus plantarum strain TWK10 (TWK10)-fermented soymilk on the protection of PC-12 cells in H2O2-, oxygen-glucose deprivation (OGD)- and deoxycorticosterone acetate (DOCA)-salt-induced rat models of VaD. Notably, the viabilities of H2O2-treated PC-12 cells and OGD model were significantly increased by treatment with TWK10-fermented soymilk ethanol extract (p < 0.05). In addition, oral administration of TWK10-fermented soymilk extract in DOCA-salt hypertension-induced VaD rats resulted in a significant decrease in blood pressure (p < 0.05), which was regulated by inhibiting ACE activity and promoting NO production, in addition to decreased escape latency and increased target crossing (p < 0.05). In conclusion, these results demonstrated that TWK10-fermented soymilk extract could improve learning and memory in DOCA-salt hypertension-induced VaD rats by acting as a blood pressure-lowering and neuroprotective agent. PMID:27144579

  2. Geobacter sulfurreducens subsp. ethanolicus, subsp. nov., an ethanol-utilizing dissimilatory Fe(III)-reducing bacterium from a lotus field.

    PubMed

    Viulu, Samson; Nakamura, Kohei; Kojima, Akihiro; Yoshiyasu, Yuki; Saitou, Sakiko; Takamizawa, Kazuhiro

    2013-01-01

    An ethanol-utilizing Fe(III)-reducing bacterial strain, OSK2A(T), was isolated from a lotus field in Aichi, Japan. Phylogenetic analysis of the 16S rRNA gene sequences of OSK2A(T) and related strains placed it within Geobacter sulfurreducens PCA(T). Strain OSK2A(T) was shown to be a Gram-negative, motile, rod-shaped bacterium, strictly anaerobic, 0.76-1.65 µm long and 0.28-0.45 μm wide. Its growth occurred at 20-40℃, pH 6.0-8.1, and it tolerated up to 1% NaCl. The G+C content of the genomic DNA was 61.2 mol% and DNA-DNA hybridization value with Geobacter sulfurreducens PCA(T) was 60.7%. The major respiratory quinone was MK-8. The major fatty acids were 16:1 ω7c, 16:0, 14:0, 15:0 iso, 16:1 ω5c, and 18:1 ω7c. Strain OSK2A(T) could utilize H2, ethanol, acetate, lactate, pyruvate, and formate as substrates with Fe(III)-citrate as electron acceptor. Amorphous Fe(III) hydroxide, Fe(III)-NTA, fumarate, malate, and elemental sulfur were utilized as electron acceptors with either acetate or ethanol as substrates. Results obtained from physiological, DNA-DNA hybridization, and chemotaxonomic tests support genotypic and phenotypic differentiation of strain OSK2A(T) from its closest relative. The isolate is assigned as a novel subspecies with the name Geobacter sulfurreducens subsp. ethanolicus, subsp. nov. (type strain OSK2A(T)=DSMZ 26126(T)=JCM 18752(T)).

  3. Inverse agonism of histamine H2 antagonist accounts for upregulation of spontaneously active histamine H2 receptors.

    PubMed Central

    Smit, M J; Leurs, R; Alewijnse, A E; Blauw, J; Van Nieuw Amerongen, G P; Van De Vrede, Y; Roovers, E; Timmerman, H

    1996-01-01

    Histamine H2 receptors transfected in Chinese hamster ovary (CHO) cells are time- and dose-dependently upregulated upon exposure to the H2 antagonists cimetidine and ranitidine. This effect appears to be H2 receptor-mediated as no change in receptor density was observed after H1 or H3 antagonist treatment or after incubation with the structural analogue of cimetidine, VUF 8299, which has no H2 antagonistic effects. By using transfected CHO cells expressing different densities of wild-type H2 receptors or an uncoupled H2Leu124Ala receptor, the histamine H2 receptor was found to display considerable agonist-independent H2 receptor activity. Cimetidine and ranitidine, which both induce H2 receptor upregulation, actually functioned as inverse agonists in those cell lines displaying spontaneous agonist-independent H2 receptor activity. Burimamide, on the other hand, was shown to act as a neutral antagonist and did as expected not induce H2 receptor upregulation after long-term exposure. The displayed inverse agonism of H2 antagonists appears to be a mechanistic basis for the observed H2 antagonist-induced H2 receptor upregulation in transfected CHO cells. These observations shed new light on the pharmacological classification of the H2 antagonists and may offer a plausible explanation for the observed development of tolerance after prolonged clinical use. Images Fig. 3 PMID:8692899

  4. Citric acid cycle in the hyperthermophilic archaeon Pyrobaculum islandicum grown autotrophically, heterotrophically, and mixotrophically with acetate.

    PubMed

    Hu, Yajing; Holden, James F

    2006-06-01

    The hyperthermophilic archaeon Pyrobaculum islandicum uses the citric acid cycle in the oxidative and reductive directions for heterotrophic and autotrophic growth, respectively, but the control of carbon flow is poorly understood. P. islandicum was grown at 95 degrees C autotrophically, heterotrophically, and mixotrophically with acetate, H2, and small amounts of yeast extract and with thiosulfate as the terminal electron acceptor. The autotrophic growth rates and maximum concentrations of cells were significantly lower than those in other media. The growth rates on H2 and 0.001% yeast extract with and without 0.05% acetate were the same, but the maximum concentration of cells was fourfold higher with acetate. There was no growth with acetate if 0.001% yeast extract was not present, and addition of H2 to acetate-containing medium greatly increased the growth rates and maximum concentrations of cells. P. islandicum cultures assimilated 14C-labeled acetate in the presence of H2 and yeast extract with an efficiency of 55%. The activities of 11 of 19 enzymes involved in the central metabolism of P. islandicum were regulated under the three different growth conditions. Pyruvate synthase and acetate:coenzyme A (CoA) ligase (ADP-forming) activities were detected only in heterotrophically grown cultures. Citrate synthase activity decreased in autotrophic and acetate-containing cultures compared to the activity in heterotrophic cultures. Acetylated citrate lyase, acetate:CoA ligase (AMP forming), and phosphoenolpyruvate carboxylase activities increased in autotrophic and acetate-containing cultures. Citrate lyase activity was higher than ATP citrate synthase activity in autotrophic cultures. These data suggest that citrate lyase and AMP-forming acetate:CoA ligase, but not ATP citrate synthase, work opposite citrate synthase to control the direction of carbon flow in the citric acid cycle.

  5. Full-dimensional, high-level ab initio potential energy surfaces for H2(H2O) and H2(H2O)2 with application to hydrogen clathrate hydrates.

    PubMed

    Homayoon, Zahra; Conte, Riccardo; Qu, Chen; Bowman, Joel M

    2015-08-28

    New, full-dimensional potential energy surfaces (PESs), obtained using precise least-squares fitting of high-level electronic energy databases, are reported for intrinsic H2(H2O) two-body and H2(H2O)2 three-body potentials. The database for H2(H2O) consists of approximately 44 000 energies at the coupled cluster singles and doubles plus perturbative triples (CCSD(T))-F12a/haQZ (aug-cc-pVQZ for O and cc-pVQZ for H) level of theory, while the database for the three-body interaction consists of more than 36 000 energies at the CCSD(T)-F12a/haTZ (aug-cc-pVTZ for O, cc-pVTZ for H) level of theory. Two precise potentials are based on the invariant-polynomial technique and are compared to computationally faster ones obtained via "purified" symmetrization. All fits use reduced permutational symmetry appropriate for these non-covalent interactions. These intrinsic potentials are employed together with existing ones for H2, H2O, and (H2O)2, to obtain full PESs for H2(H2O) and H2(H2O)2. Properties of these full PESs are presented, including a diffusion Monte Carlo calculation of the zero-point energy and wavefunction, and dissociation energy of the H2(H2O) dimer. These PESs together with an existing one for water clusters are used in a many-body representation of the PES of hydrogen clathrate hydrates, illustrated for H2@(H2O)20. An analysis of this hydrate is presented, including the electronic dissociation energy to remove H2 from the calculated equilibrium structure.

  6. The relationship between instability of H2 production and compositions of bacterial communities within a dark fermentation fluidized-bed bioreactor.

    PubMed

    Koskinen, Perttu E P; Kaksonen, Anna H; Puhakka, Jaakko A

    2007-07-01

    Microbial community composition dynamics was studied during H(2) fermentation from glucose in a fluidized-bed bioreactor (FBR) aiming at obtaining insight into the H(2) fermentation microbiology and factors resulting in the instability of biofilm processes. FBR H(2) production performance was characterised by an instable pattern of prompt onset of H(2) production followed by rapid decrease. Gradual enrichment of organisms increased the diversity of FBR attached and suspended-growth phase bacterial communities during the operation. FBR bacteria included potential H(2) producers, H(2) consumers and neither H(2) producers nor consumers, and those distantly related to any known organisms. The prompt onset of H(2) production was due to rapid growth of Clostridium butyricum (99-100%) affiliated strains after starting continuous feed. The proportion trend of C. butyricum in FBR attached and suspended-growth phase communities coincided with H(2) and butyrate production. High glucose loading rate favoured the H(2) production by Escherichia coli (100%) affiliated strain. Decrease in H(2) production, associated with a shift from acetate-butyrate to acetate-propionate production, was due to changes in FBR attached and suspended-growth phase bacterial community compositions. During the shift, organisms, including potential propionate producers, were enriched in the communities while the proportion trend of C. butyricum decreased. We suggest that the instability of H(2) fermentation in biofilm reactors is due to enrichment and efficient adhesion of H(2) consumers on the carrier and, therefore, biofilm reactors may not favour mesophilic H(2) fermentation.

  7. Understanding the role of H(2)O(2) during pea seed germination: a combined proteomic and hormone profiling approach.

    PubMed

    Barba-Espín, Gregorio; Diaz-Vivancos, Pedro; Job, Dominique; Belghazi, Maya; Job, Claudette; Hernández, José Antonio

    2011-11-01

    In a previous publication, we showed that the treatment of pea seeds in the presence of hydrogen peroxide (H(2)O(2)) increased germination performance as well as seedling growth. To gain insight into the mechanisms responsible for this behaviour, we have analysed the effect of treating mature pea seeds in the presence of 20 mm H(2)O(2) on several oxidative features such as protein carbonylation, endogenous H(2)O(2) and lipid peroxidation levels. We report that H(2)O(2) treatment of the pea seeds increased their endogenous H(2)O(2) content and caused carbonylation of storage proteins and of several metabolic enzymes. Under the same conditions, we also monitored the expression of two MAPK genes known to be activated by H(2)O(2) in adult pea plants. The expression of one of them, PsMAPK2, largely increased upon pea seed imbibition in H(2)O(2) , whereas no change could be observed in expression of the other, PsMAPK3. The levels of several phytohormones such as 1-aminocyclopropane carboxylic acid, indole-3-acetic acid and zeatin appeared to correlate with the measured oxidative indicators and with the expression of PsMAPK2. Globally, our results suggest a key role of H(2)O(2) in the coordination of pea seed germination, acting as a priming factor that involves specific changes at the proteome, transcriptome and hormonal levels.

  8. [Effect of Residual Hydrogen Peroxide on Hydrolysis Acidification of Sludge Pretreated by Microwave -H2O2-Alkaline Process].

    PubMed

    Jia, Rui-lai; Liu, Ji-bao; Wei, Yuan-song; Cai, Xing

    2015-10-01

    MW-H2O2-OH(pH = 11) + catalase group, the dominant VFAs were acetic, iso-valeric and n-butyric acids. For MW-H2O2-OH (pH = 11) group, the dominant VFAs were acetic, propionic and iso-valeric acids. In the optimized hydrolysis acidification time for each group, percentages of the three main acids accounted for more than 75% of total VFAs, and percentages of acetic acid accounted for more than 41% of total VFAs.

  9. Acetic Acid Production by an Electrodialysis Fermentation Method with a Computerized Control System

    PubMed Central

    Nomura, Yoshiyuki; Iwahara, Masayoshi; Hongo, Motoyoshi

    1988-01-01

    In acetic acid fermentation by Acetobacter aceti, the acetic acid produced inhibits the production of acetic acid by this microorganism. To alleviate this inhibitory effect, we developed an electrodialysis fermentation method such that acetic acid is continuously removed from the broth. The fermentation unit has a computerized system for the control of the pH and the concentration of ethanol in the fermentation broth. The electrodialysis fermentation system resulted in improved cell growth and higher productivity over an extended period; the productivity exceeded that from non-pH-controlled fermentation. During electrodialysis fermentation in our system, 97.6 g of acetic acid was produced from 86.0 g of ethanol; the amount of acetic acid was about 2.4 times greater than that produced by non-pH-controlled fermentation (40.1 g of acetic acid produced from 33.8 g of ethanol). Maximum productivity of electrodialysis fermentation in our system was 2.13 g/h, a rate which was 1.35 times higher than that of non-pH-controlled fermentation (1.58 g/h). PMID:16347520

  10. Point mutation of H3/H4 histones affects acetic acid tolerance in Saccharomyces cerevisiae.

    PubMed

    Liu, Xiangyong; Zhang, Xiaohua; Zhang, Zhaojie

    2014-10-10

    The molecular mechanism of acetic acid tolerance in yeast remains unclear despite of its importance for efficient cellulosic ethanol production. In this study, we examined the effects of histone H3/H4 point mutations on yeast acetic acid tolerance by comprehensively screening a histone H3/H4 mutant library. A total of 24 histone H3/H4 mutants (six acetic acid resistant and 18 sensitive) were identified. Compared to the wild-type strain, the histone acetic acid-resistant mutants exhibited improved ethanol fermentation performance under acetic acid stress. Genome-wide transcriptome analysis revealed that changes in the gene expression in the acetic acid-resistant mutants H3 K37A and H4 K16Q were mainly related to energy production, antioxidative stress. Our results provide novel insights into yeast acetic acid tolerance on the basis of histone, and suggest a novel approach to improve ethanol production by altering the histone H3/H4 sequences.

  11. Hydrogen constituents of the mesosphere inferred from positive ions - H2O, CH4, H2CO, H2O2, and HCN

    NASA Technical Reports Server (NTRS)

    Kopp, E.

    1990-01-01

    The concentrations in the mesosphere of H2O, CH4, H2CO, H2O2, and HCN were inferred from data on positive ion compositions, obtained from one mid-latitude and four high-latitude rocket flights. The inferred concentrations were found to agree only partially with the ground-based microwave measurements and/or model prediction by Garcia and Solomon (1985). The CH4 concentration was found to vary between 70 and 4 ppb in daytime and 900 and 100 ppbv at night, respectively. Unexpectedly high H2CO concentrations were obtained, with H2CO/H2O ratios between 0.0006 and 0.1, and a mean HCN volume mixing ratio of 6 x 10 to the -10th was inferred.

  12. Simple purification of recovered [18O]H2O by UV, ozone, and solid-phase extraction methods.

    PubMed

    Moon, Woo Yeon; Oh, Seung Jun; Cheon, Jun Hong; Chae, Won Seok; Lim, Sung Jae; Cho, Si Man; Moon, Dae Hyuk

    2007-06-01

    We have developed three methods for removing organic impurities as well as a solid-phase extraction (SPE) method for removing metallic and ionic impurities from recovered [18O]H2O. Preliminary experiments with [16O]H2O were used to determine the optimal purification conditions. These showed that UV irradiation rapidly (<4 h) eliminated low boiling point impurities such as acetonitrile and acetone with only a slight loss of mass. A combination of UV irradiation and purging with ozone removed high boiling point impurities such as ethanol and methanol more quickly than UV irradiation alone. UV irradiation followed by a SPE with [18O]H2O removed all organic and inorganic impurities. The purified [18O]H2O gave a saturation yield of 128.62+/-15.6 mCi/microA for [18F]fluoride and a 49.8+/-12.7% radiochemical yield for [18F]fluorodeoxyglucose.

  13. Ethanol production from cotton gin trash using optimised dilute acid pretreatment and whole slurry fermentation processes.

    PubMed

    McIntosh, S; Vancov, T; Palmer, J; Morris, S

    2014-12-01

    Cotton ginning trash (CGT) collected from Australian cotton gins was evaluated for bioethanol production. CGT composition varied between ginning operations and contained high levels of extractives (26-28%), acid-insoluble material (17-22%) and holocellulose (42-50%). Pretreatment conditions of time (4-20 min), temperature (160-220 °C) and sulfuric acid concentration (0-2%) were optimised using a central composite design. Response surface modelling revealed that CGT fibre pretreated at 180 °C in 0.8% H2SO4 for 12 min was optimal for maximising enzymatic glucose recoveries and achieved yields of 89% theoretical, whilst the total accumulated levels of furans and acetic acid remained relatively low at <1 and 2 g/L respectively. Response surface modelling also estimated maximum xylose recovery in pretreated liquors (87% theoretical) under the set conditions of 150 °C in 1.9% H2SO4 for 23.8 min. Yeast fermentations yielded high ethanol titres of 85%, 88% and 70% theoretical from glucose generated from: (a) enzymatic hydrolysis of washed pretreated fibres, (b) enzymatic hydrolysis of whole pretreated slurries and (c) simultaneous saccharification fermentations, respectively.

  14. An accurate H2-H2 interaction potential from first principles

    NASA Astrophysics Data System (ADS)

    Diep, Phong; Johnson, J. Karl

    2000-03-01

    We have calculated the potential energy surface extrapolated to the complete basis set limit using coupled-cluster theory with singles, doubles, and perturbational triples excitations [CCSD(T)] for the rigid monomer model of (H2)2. There is significant anisotropy among the 37 unique angular configurations selected to represent the surface. A four term spherical harmonics expansion model was chosen to fit the surface. The calculated potential energy surface reproduces the quadrupole moment to within 0.58% and the experimental well depth to within 1%. The second virial coefficient has been computed from the fitted potential energy surface. The usual semiclassical treatment of quantum mechanical effects on the second virial coefficient was applied in the temperature range of 100-500 K. We have developed a new technique for computing the quantum second virial coefficient by combining Feynman's path integral formalism and Monte Carlo integration. The calculated virial coefficient compares very well with published experimental measurements. Integral elastic cross sections were calculated for the scattering of para-H2/para-H2 by use of the close-coupling method. The interaction potential model from this work is able to reproduce the experimental cross sections in the relative kinetic velocity range of 900-2300 m/s.

  15. Microbial contamination of fuel ethanol fermentations.

    PubMed

    Beckner, M; Ivey, M L; Phister, T G

    2011-10-01

    Microbial contamination is a pervasive problem in any ethanol fermentation system. These infections can at minimum affect the efficiency of the fermentation and at their worse lead to stuck fermentations causing plants to shut down for cleaning before beginning anew. These delays can result in costly loss of time as well as lead to an increased cost of the final product. Lactic acid bacteria (LAB) are the most common bacterial contaminants found in ethanol production facilities and have been linked to decreased ethanol production during fermentation. Lactobacillus sp. generally predominant as these bacteria are well adapted for survival under high ethanol, low pH and low oxygen conditions found during fermentation. It has been generally accepted that lactobacilli cause inhibition of Saccharomyces sp. and limit ethanol production through two basic methods; either production of lactic and acetic acids or through competition for nutrients. However, a number of researchers have demonstrated that these mechanisms may not completely account for the amount of loss observed and have suggested other means by which bacteria can inhibit yeast growth and ethanol production. While LAB are the primary contaminates of concern in industrial ethanol fermentations, wild yeast may also affect the productivity of these fermentations. Though many yeast species have the ability to thrive in a fermentation environment, Dekkera bruxellensis has been repeatedly targeted and cited as one of the main contaminant yeasts in ethanol production. Though widely studied for its detrimental effects on wine, the specific species-species interactions between D. bruxellensis and S. cerevisiae are still poorly understood.

  16. [Effects of catalase activators and inhibitors on ethanol pharmacokinetic characteristics and ethanol and aldehyde-metabolizing enzyme activities in the rat liver and brain].

    PubMed

    Bardina, L R; Pron'ko, P S; Satanovskaia, V I; Alieva, E V

    2010-01-01

    The effects of catalase regulators (aminotriazole, lead acetate, taurine, di-2-ethylhexylphthalate) on the preference for ethanol, its pharmacokinetics, and activities of rat liver and brain ethanol and acetaldehyde-metabolizing enzymes were studied. Lead acetate (100 mg/kg, i.p., 7 days), aminotriazole (1 g/kg, i.p., 7 days), and taurine (650 mg/kg, i.g., 14 days) decreased ethanol consumption under conditions of free choice (10% ethanol water), whereas di-2-ethylhexylphthalate (300 mg/kg, i.g., 7 days) did not exert any effect on this parameter. Taurine, lead acetate and di-2-ethylhexylphthalate significantly activated liver ADH, MEOS and catalase peroxidase activity. Aminotriazole also activated ADH and MEOS, but inhibited liver catalase. The activities of liver and brain A1DH as well as catalase were insignificantly changed by this treatment. The 7-day administration of lead acetate, di-2-ethylhexylphthalate and aminotriazole administrations significantly influenced the ethanol (2 g/kg., i.p.) pharmacokinetic parameters: the area under the pharmacokinetic curve and the elimination half-life time were significantly reduced, whereas the elimination constant and clearance were increased. This unequivocally indicates accelerated ethanol elimination. The 14-day ingestion of taurine insignificantly changed the parameters of ethanol pharmacokinetics in rats.

  17. Fluorescent Probes for H2S Detection and Quantification.

    PubMed

    Feng, Wei; Dymock, Brian W

    2015-01-01

    Many diverse, sensitive and structurally novel fluorescent probes have recently been reported for H2S detection. Quantification of H2S requires a selective chemosensor which will react only with H2S against a background of high concentrations of other thiols or reducing agents. Most published probes are able to quantify H2S selectively in a simple in vitro system with the most sensitive probes able to detect H2S at below 100 nM concentrations. A subset of probes also have utility in sensing H2S in living cells, and there are now several with specific sub-cellular localization and a few cases of in vivo applications. Biologists studying H2S now have a wide range of tools to assist them to aid further understanding of the role of H2S in biology.

  18. Incorporating H2 Dynamics and Inhibition into a Microbially Based Methanogenesis Model for Restored Wetland Sediments

    NASA Astrophysics Data System (ADS)

    Pal, David; Jaffe, Peter

    2015-04-01

    Estimates of global CH4 emissions from wetlands indicate that wetlands are the largest natural source of CH4 to the atmosphere. In this paper, we propose that there is a missing component to these models that should be addressed. CH4 is produced in wetland sediments from the microbial degradation of organic carbon through multiple fermentation steps and methanogenesis pathways. There are multiple sources of carbon for methananogenesis; in vegetated wetland sediments, microbial communities consume root exudates as a major source of organic carbon. In many methane models propionate is used as a model carbon molecule. This simple sugar is fermented into acetate and H2, acetate is transformed to methane and CO2, while the H2 and CO2 are used to form an additional CH4 molecule. The hydrogenotrophic pathway involves the equilibrium of two dissolved gases, CH4 and H2. In an effort to limit CH4 emissions from wetlands, there has been growing interest in finding ways to limit plant transport of soil gases through root systems. Changing planted species, or genetically modifying new species of plants may control this transport of soil gases. While this may decrease the direct emissions of methane, there is little understanding about how H2 dynamics may feedback into overall methane production. The results of an incubation study were combined with a new model of propionate degradation for methanogenesis that also examines other natural parameters (i.e. gas transport through plants). This presentation examines how we would expect this model to behave in a natural field setting with changing sulfate and carbon loading schemes. These changes can be controlled through new plant species and other management practices. Next, we compare the behavior of two variations of this model, with or without the incorporation of H2 interactions, with changing sulfate, carbon loading and root volatilization. Results show that while the models behave similarly there may be a discrepancy of nearly

  19. Mass spectrometric approach for characterizing the disordered tail regions of the histone H2A/H2B dimer.

    PubMed

    Saikusa, Kazumi; Nagadoi, Aritaka; Hara, Kana; Fuchigami, Sotaro; Kurumizaka, Hitoshi; Nishimura, Yoshifumi; Akashi, Satoko

    2015-02-17

    The histone H2A/H2B dimer is a component of nucleosome core particles (NCPs). The structure of the dimer at the atomic level has not yet been revealed. A possible reason for this is that the dimer has three intrinsically disordered tail regions: the N- and C-termini of H2A and the N-terminus of H2B. To investigate the role of the tail regions of the H2A/H2B dimer structure, we characterized behaviors of the H2A/H2B mutant dimers, in which these functionally important disordered regions were depleted, using mass spectrometry (MS). After verifying that the acetylation of Lys residues in the tail regions had little effect on the gas-phase conformations of the wild-type dimer, we prepared two histone H2A/H2B dimer mutants: an H2A/H2B dimer depleted of both N-termini (dN-H2A/dN-H2B) and a dimer with the N- and C-termini of H2A and the N-terminus of H2B depleted (dNC-H2A/dN-H2B). We analyzed these mutants using ion mobility-mass spectrometry (IM-MS) and hydrogen/deuterium exchange mass spectrometry (HDX-MS). With IM-MS, reduced structural diversity was observed for each of the tail-truncated H2A/H2B mutants. In addition, global HDX-MS proved that the dimer mutant dNC-H2A/dN-H2B was susceptible to deuteration, suggesting that its structure in solution was somewhat loosened. A partial relaxation of the mutant's structure was demonstrated also by IM-MS. In this study, we characterized the relationship between the tail lengths and the conformations of the H2A/H2B dimer in solution and gas phases, and demonstrated, using mass spectrometry, that disordered tail regions play an important role in stabilizing the conformation of the core region of the dimer in both phases.

  20. Electronic states and potential energy surfaces of H2Te, H2Po, and their positive ions

    NASA Astrophysics Data System (ADS)

    Sumathi, K.; Balasubramanian, K.

    1990-06-01

    Geometries, bond energies, ionization potentials, dipole moments, other one-electron properties, and potential energy surfaces of six valence electronic states of H2Te and H2Po species are obtained using the relativistic complete active space multiconfiguration self-consistent field (CASSCF) followed by full second-order configuration interaction (SOCI) and relativistic configuration interaction (RCI) calculations including spin-orbit coupling. In addition, Rydberg states of H2Te and H2Se are studied to interpret the experimental spectra. The potential energy surfaces of two electronic states of H2Te+ and H2Po+ are obtained. The ground states of both H2Te and H2Po are found to be of X 1A1(A1) symmetry with bent (C2v) equilibrium geometries of H2Te:re =1.668 Å, θe=91.2°; and H2Po:re =1.835 Å and θe=90.9°. The ground states of H2Te+ and H2Po+ are X 2B1 with H2Te+:re =1.676 Å, θe=90.7° and H2Po+:re =1.828 Å and θe=88°. The De (HTe-H) and De (HPo-H) including spin-orbit effects are calculated as 63.2 and 39.4 kcal/mol, respectively. The X 2B1(E)-A 2A1(E) energy separations of H2Te+ and H2Po+ ions are calculated as 66.6 and 76 kcal/mol, respectively. The adiabatic IPs of H2Te and H2Po are calculated as 8.47 and 7.79 eV, respectively. In addition CASSCF/SOCI/RCI calculations are also carried out on the X 2Π3/2 and 2Π1/2 states of TeH and PoH diatomics. The X 2Π3/2-2Π1/2 energy separations of TeH and PoH are computed as 3710 and 9920 cm-1, respectively. Spin-orbit effects are thus found to be very significant for PoH and H2Po. All excited states of H2Te and H2Po are above 3.7 and 3.1 eV, respectively. Properties and energy separations of H2Te and H2Po are compared with the lighter group (VI) H2Ch species.

  1. Synthesis and crystal structure analysis of uranyl triple acetates

    NASA Astrophysics Data System (ADS)

    Klepov, Vladislav V.; Serezhkina, Larisa B.; Serezhkin, Victor N.; Alekseev, Evgeny V.

    2016-12-01

    Single crystals of triple acetates NaR[UO2(CH3COO)3]3·6H2O (R=Mg, Co, Ni, Zn), well-known for their use as reagents for sodium determination, were grown from aqueous solutions and their structural and spectroscopic properties were studied. Crystal structures of the mentioned phases are based upon {Na[UO2(CH3COO)3]3}2- clusters and [R(H2O)6]2+ aqua-complexes. The cooling of a single crystal of NaMg[UO2(CH3COO)3]3·6H2O from 300 to 100 K leads to a phase transition from trigonal to monoclinic crystal system. Intermolecular interactions between the structural units and their mutual packing were studied and compared from the point of view of the stereoatomic model of crystal structures based on Voronoi-Dirichlet tessellation. Using this method we compared the crystal structures of the triple acetates with Na[UO2(CH3COO)3] and [R(H2O)6][UO2(CH3COO)3]2 and proposed reasons of triple acetates stability. Infrared and Raman spectra were collected and their bands were assigned.

  2. Ethanol production from cellulose by two lignocellulolytic soil fungi

    SciTech Connect

    Durrant, L.R.

    1996-12-31

    The present work examines the production of ethanol via direct fermentation of pure celluloses and lignocellulosic wastes by two soil fungi isolated under anaerobic conditions. The strains were cultured on a defined medium containing filter paper slurry as the carbon source under anaerobic, microaerophilic, and aerobic conditions. After complete degradation of the cellulose, lignocellulases and fermentation products were determined. Highest activities for Trichocladium canadense (strain Q10) and the basidiomycete strain (strain H2), were obtained when cultures were incubated under microaerophilic conditions and air, respectively. Laccase activity was present in the culture supernatants of both strains, but peroxidase was only produced by strain H2. Ethanol was the major nongaseous fermentation product. Highest conversion of available cellulose to ethanol was obtained with strain Q10 (90-96%), under microaerophilic conditions. Ethanol production decreased when microcrystalline cellulose and lignocellulosic substrates were used. 29 refs., 4 figs., 2 tabs.

  3. Biological production of ethanol fom coal. [Quarterly report], December 22, 1991--March 21, 1992

    SciTech Connect

    Not Available

    1992-05-01

    Research is continuing in an attempt to increase both the ethanol concentration and product ratio using C. ljungdahlii. The purpose of this report is to present data (acetate to ethanol) utilizing a medium prepared especially for C. ljungdahlii. Medium development studies are presented, as well as reactor studies with the new medium in batch reactors. Continuous stirred tank reactor (CSTR) with cell recycle. The use of this new medium has resulted in significant improvements in cell concentration, ethanol concentration and product ratio.

  4. Selection of a Bifidobacterium animalis subsp. lactis Strain with a Decreased Ability To Produce Acetic Acid

    PubMed Central

    Margolles, Abelardo

    2012-01-01

    We have characterized a new strain, Bifidobacterium animalis subsp. lactis CECT 7953, obtained by random UV mutagenesis, which produces less acetic acid than the wild type (CECT 7954) in three different experimental settings: De Man-Rogosa-Sharpe broth without sodium acetate, resting cells, and skim milk. Genome sequencing revealed a single Phe-Ser substitution in the acetate kinase gene product that seems to be responsible for the strain's reduced acid production. Accordingly, acetate kinase specific activity was lower in the low acetate producer. Strain CECT 7953 produced less acetate, less ethanol, and more yoghourt-related volatile compounds in skim milk than the wild type did. Thus, CECT 7953 shows promising potential for the development of dairy products fermented exclusively by a bifidobacterial strain. PMID:22389372

  5. Selection of a Bifidobacterium animalis subsp. lactis strain with a decreased ability to produce acetic acid.

    PubMed

    Margolles, Abelardo; Sánchez, Borja

    2012-05-01

    We have characterized a new strain, Bifidobacterium animalis subsp. lactis CECT 7953, obtained by random UV mutagenesis, which produces less acetic acid than the wild type (CECT 7954) in three different experimental settings: De Man-Rogosa-Sharpe broth without sodium acetate, resting cells, and skim milk. Genome sequencing revealed a single Phe-Ser substitution in the acetate kinase gene product that seems to be responsible for the strain's reduced acid production. Accordingly, acetate kinase specific activity was lower in the low acetate producer. Strain CECT 7953 produced less acetate, less ethanol, and more yoghourt-related volatile compounds in skim milk than the wild type did. Thus, CECT 7953 shows promising potential for the development of dairy products fermented exclusively by a bifidobacterial strain.

  6. Dynamics of yeast histone H2A and H2B phosphorylation in response to a double-strand break.

    PubMed

    Lee, Cheng-Sheng; Lee, Kihoon; Legube, Gaëlle; Haber, James E

    2014-01-01

    In budding yeast, a single double-strand break (DSB) triggers extensive Tel1 (ATM)- and Mec1 (ATR)-dependent phosphorylation of histone H2A around the DSB, to form γ-H2AX. We describe Mec1- and Tel1-dependent phosphorylation of histone H2B at T129. γ-H2B formation is impaired by γ-H2AX and its binding partner Rad9. High-density microarray analyses show similar γ-H2AX and γ-H2B distributions, but γ-H2B is absent near telomeres. Both γ-H2AX and γ-H2B are strongly diminished over highly transcribed regions. When transcription of GAL7, GAL10 and GAL1 genes is turned off, γ-H2AX is restored within 5 min, in a Mec1-dependent manner; after reinduction of these genes, γ-H2AX is rapidly lost. Moreover, when a DSB is induced near CEN2, γ-H2AX spreads to all other pericentromeric regions, again depending on Mec1. Our data provide new insights in the function and establishment of phosphorylation events occurring on chromatin after DSB induction.

  7. Histone H2A (H2A.X and H2A.Z) Variants in Molluscs: Molecular Characterization and Potential Implications For Chromatin Dynamics

    PubMed Central

    González-Romero, Rodrigo; Rivera-Casas, Ciro; Frehlick, Lindsay J.; Méndez, Josefina; Ausió, Juan; Eirín-López, José M.

    2012-01-01

    Histone variants are used by the cell to build specialized nucleosomes, replacing canonical histones and generating functionally specialized chromatin domains. Among many other processes, the specialization imparted by histone H2A (H2A.X and H2A.Z) variants to the nucleosome core particle constitutes the earliest response to DNA damage in the cell. Consequently, chromatin-based genotoxicity tests have been developed in those cases where enough information pertaining chromatin structure and dynamics is available (i.e., human and mouse). However, detailed chromatin knowledge is almost absent in most organisms, specially protostome animals. Molluscs (which represent sentinel organisms for the study of pollution) are not an exception to this lack of knowledge. In the present work we first identified the existence of functionally differentiated histone H2A.X and H2A.Z variants in the mussel Mytilus galloprovincialis (MgH2A.X and MgH2A.Z), a marine organism widely used in biomonitoring programs. Our results support the functional specialization of these variants based on: a) their active expression in different tissues, as revealed by the isolation of native MgH2A.X and MgH2A.Z proteins in gonad and hepatopancreas; b) the evolutionary conservation of different residues encompassing functional relevance; and c) their ability to confer specialization to nucleosomes, as revealed by nucleosome reconstitution experiments using recombinant MgH2A.X and MgH2A.Z histones. Given the seminal role of these variants in maintaining genomic integrity and regulating gene expression, their preliminary characterization opens up new potential applications for the future development of chromatin-based genotoxicity tests in pollution biomonitoring programs. PMID:22253857

  8. Production of Excess CO2 relative to methane in peatlands: a new H2 sink

    NASA Astrophysics Data System (ADS)

    Wilson, R.; Woodcroft, B. J.; Varner, R. K.; Tyson, G. W.; Tfaily, M. M.; Sebestyen, S.; Saleska, S. R.; Rogers, K.; Rich, V. I.; McFarlane, K. J.; Kostka, J. E.; Kolka, R. K.; Keller, J.; Iversen, C. M.; Hodgkins, S. B.; Hanson, P. J.; Guilderson, T. P.; Griffiths, N.; de La Cruz, F.; Crill, P. M.; Chanton, J.; Bridgham, S. D.; Barlaz, M.

    2015-12-01

    Methane is generated as the end product of anaerobic organic matter degradation following a series of reaction pathways including fermentation and syntrophy. Along with acetate and CO2, syntrophic reactions generate H2 and are only thermodynamically feasible when coupled to an exothermic reaction that consumes H2. The usual model of organic matter degradation in peatlands has assumed that methanogenesis is that exothermic H2-consuming reaction. If correct, this paradigm should ultimately result in equimolar production of CO2 and methane from the degradation of the model organic compound cellulose: i.e. C6H12O6 à 3CO2 + 3CH4. However, dissolved gas measurement and modeling results from field and incubation experiments spanning peatlands across the northern hemisphere have failed to demonstrate equimolar production of CO2 and methane. Instead, in a flagrant violation of thermodynamics, these studies show a large bias favoring CO2 production over methane generation. In this talk, we will use an array of complementary analytical techniques including FT-IR, cellulose and lignin measurements, 13C-NMR, fluorescence spectroscopy, and ultra-high resolution mass spectrometry to describe organic matter degradation within a peat column and identify the important degradation mechanisms. Hydrogenation was the most common transformation observed in the ultra-high resolution mass spectrometry data. From these results we propose a new mechanism for consuming H2 generated during CO2 production, without concomitant methane formation, consistent with observed high CO2/CH4 ratios. While homoacetogenesis is a known sink for H2 in these systems, this process also consumes CO2 and therefore does not explain the excess CO2 measured in field and incubation samples. Not only does the newly proposed mechanism consume H2 without generating methane, but it also yields enough energy to balance the coupled syntrophic reactions, thereby restoring thermodynamic order. Schematic of organic matter

  9. Organelle-Targeted H2S Probes Enable Visualization of the Subcellular Distribution of H2S Donors.

    PubMed

    Montoya, Leticia A; Pluth, Michael D

    2016-06-07

    Hydrogen sulfide (H2S) is an essential biological signaling molecule in diverse biological regulatory pathways. To provide new chemical tools for H2S imaging, we report here a fluorescent H2S detection platform (HSN2-BG) that is compatible with subcellular localization SNAP-tag fusion protein methodologies and use appropriate fusion protein constructs to demonstrate mitochondrial and lysosomal localization. We also demonstrate the efficacy of this detection platform to image endogenous H2S in Chinese hamster ovary (CHO) cells and use the developed constructs to report on the subcellular H2S distributions provided by common H2S donor molecules AP39, ADT-OH, GYY4137, and diallyltrisulfide (DATS). The developed constructs provide a platform poised to provide new insights into the subcellular distribution of common H2S donors and a useful tool for investigating H2S biochemistry.

  10. Thermodynamic and transport properties of frozen and reacting pH2-oH2 mixtures

    NASA Technical Reports Server (NTRS)

    Carter, H. G.; Bullock, R. E.

    1972-01-01

    Application of experimental state data and spectroscopic term values shows that the thermodynamic and transport properties of reacting pH2-oH2 mixtures are considerably different than those of chemically frozen pH2 at temperatures below 300 R. Calculated H-S data also show that radiation-induced pH2-oH2 equilibration at constant enthalpy produces a temperature drop of at least 28 R, corresponding to an ideal shaft work loss of 15% or more for a turbine operating downstream from the point of conversion. Aside from differences in thermodynamic and transport properties, frozen pH2-oH2 mixtures may differ from pure pH2 on a purely hydrodynamical basis.

  11. Characterization of acetic acid bacteria in "traditional balsamic vinegar".

    PubMed

    Gullo, Maria; Caggia, Cinzia; De Vero, Luciana; Giudici, Paolo

    2006-02-01

    This study evaluated the glucose tolerance of acetic acid bacteria strains isolated from Traditional Balsamic Vinegar. The results showed that the greatest hurdle to acetic acid bacteria growth is the high sugar concentration, since the majority of the isolated strains are inhibited by 25% of glucose. Sugar tolerance is an important technological trait because Traditional Balsamic Vinegar is made with concentrated cooked must. On the contrary, ethanol concentration of the cooked and fermented must is less significant for acetic acid bacteria growth. A tentative identification of the isolated strains was done by 16S-23S-5S rDNA PCR/RFLP technique and the isolated strains were clustered: 32 strains belong to Gluconacetobacter xylinus group, two strains to Acetobacter pasteurianus group and one to Acetobacter aceti.

  12. Updated H2SO4-H2O binary homogeneous nucleation look-up tables

    NASA Astrophysics Data System (ADS)

    Yu, Fangqun

    2008-12-01

    The calculated rates of H2SO4-H2O binary homogeneous nucleation (BHN), which is the only nucleation mechanism currently widely used in global aerosol models, are well known to have large uncertainties. Recently, we have reduced the uncertainties in the BHN rates on the basis of a kinetic quasi-unary nucleation (KQUN) model, by taking into account the measured bonding energetics of H2SO4 monomers with hydrated sulfuric acid dimers and trimers. The uncertainties were further reduced by using two independent measurements to constrain the equilibrium constants for monomer hydration. In this paper, we present updated BHN rate look-up tables derived from the improved KQUN model which can be used by anyone to obtain the BHN rates under given conditions. The look-up tables cover a wide range of key parameters that can be found in the atmosphere and laboratory studies, and their usage significantly reduces the computational costs of the BHN rate calculations, which is critical for multidimensional modeling. The look-up tables can also be used by those involved in experiments and field measurements to quickly assess the likeliness of BHN. For quick application, one can obtain the BHN rates and properties of critical clusters by browsing through the tables. A comparison of results based on the look-up tables with those from widely used classical BHN model indicates that, in addition to several orders of magnitude difference in nucleation rates, there also exists substantial difference in the predicted numbers of sulfuric acid molecules in the critical clusters and their dependence on key parameters.

  13. EERE-SBIR technology transfer opportunity. H2 Safety Sensors for H2

    SciTech Connect

    Johnston, Mariann R.

    2015-12-01

    The Office of Energy Efficiency and Renewable Energy’s Fuel Cell Technologies Office (FCTO) works in partnership with industry (including small businesses), academia, and DOE's national laboratories to establish fuel cell and hydrogen energy technologies as economically competitive contributors to U.S. transportation needs. The work that is envisioned between the SBIR/STTR grantee and Los Alamos National Laboratory would involve Technical Transfer of Los Alamos Intellectual Property (IP) on Thin-film Mixed Potential Sensor (U.S. Patent 7,264,700) and associated know-how for H2 sensor manufacturing and packaging.

  14. Full CI calibration of model hamiltonian, large basis set studies of the H 2-H 2 van der Waals interaction.

    NASA Astrophysics Data System (ADS)

    Burton, P. G.

    1983-08-01

    The non-variational CEPA2 PNO ansatz, recently employed in detailed studies of the H 2-H 2 van der Waals interaction by Burton and Senff and the full CI extrapolation studies on the same system by Burton are discussed in relation to the explicit full CI study of Harrison and Handy for the planar T configuration of H 2-H 2 ( R = 6.5 ao) in a basis of 80 functions.

  15. Observations of the H2S toward OMC-1

    NASA Technical Reports Server (NTRS)

    Minh, Y. C.; Irvine, W. M.; Mcgonagle, D.; Ziurys, L. M.

    1990-01-01

    Observations of the 1(10) - 1(01) transition of interstellar H2S and its isotopes toward OMC-1 are reported. The fractional abundance of H2S in the quiescent regions of OMC-1 seems difficult to explain by currently known ion-molecular reactions. The fractional abundance of H2S relative to H2 is enhanced by a factor of 1000 in the hot core and the plateau relative to the quiescent clouds. The (HDS)/(H2S) abundance ratio in the hot core is estimated at 0.02 or less.

  16. H2S regulation of nitric oxide metabolism

    PubMed Central

    Kolluru, Gopi K.; Yuan, Shuai; Shen, Xinggui; Kevil, Christopher G.

    2015-01-01

    Nitric oxide (NO) and hydrogen sulfide (H2S) are two major gaseous signaling molecules that regulate diverse physiological functions. Recent publications indicate the regulatory role of H2S on NO metabolism. In this chapter, we discuss the latest findings on H2S-NO interactions through formation of novel chemical derivatives, and experimental approaches to study these adducts. This chapter also addresses potential H2S interference on various NO detection techniques, along with precautions for analyzing biological samples from various sources. This information will facilitate critical evaluation and clearer insight into H2S regulation of NO signaling and its influence on various physiological functions. PMID:25725527

  17. FACT Disrupts Nucleosome Structure by Binding H2A-H2B with Conserved Peptide Motifs.

    PubMed

    Kemble, David J; McCullough, Laura L; Whitby, Frank G; Formosa, Tim; Hill, Christopher P

    2015-10-15

    FACT, a heterodimer of Spt16 and Pob3, is an essential histone chaperone. We show that the H2A-H2B binding activity that is central to FACT function resides in short acidic regions near the C termini of each subunit. Mutations throughout these regions affect binding and cause correlated phenotypes that range from mild to lethal, with the largest individual contributions unexpectedly coming from an aromatic residue and a nearby carboxylate residue within each domain. Spt16 and Pob3 bind overlapping sites on H2A-H2B, and Spt16-Pob3 heterodimers simultaneously bind two H2A-H2B dimers, the same stoichiometry as the components of a nucleosome. An Spt16:H2A-H2B crystal structure explains the biochemical and genetic data, provides a model for Pob3 binding, and implies a mechanism for FACT reorganization that we confirm biochemically. Moreover, unexpected similarity to binding of ANP32E and Swr1 with H2A.Z-H2B reveals that diverse H2A-H2B chaperones use common mechanisms of histone binding and regulating nucleosome functions.

  18. FACT disrupts nucleosome structure by binding H2A-H2B with conserved peptide motifs

    PubMed Central

    Kemble, David J.; McCullough, Laura L.; Whitby, Frank G.; Formosa, Tim; Hill, Christopher P.

    2015-01-01

    SUMMARY FACT, a heterodimer of Spt16 and Pob3, is an essential histone chaperone. We show that the H2A-H2B binding activity that is central to FACT function resides in short acidic regions near the C-termini of each subunit. Mutations throughout these regions impact binding and cause correlated phenotypes that range from mild to lethal, with the largest individual contributions unexpectedly coming from an aromatic residue and a nearby carboxylate residue within each domain. Spt16 and Pob3 bind overlapping sites on H2A-H2B, and Spt16-Pob3 heterodimers simultaneously bind two H2A-H2B dimers, the same stoichiometry as the components of a nucleosome. An Spt16:H2A-H2B crystal structure explains the biochemical and genetic data, provides a model for Pob3 binding, and implies a mechanism for FACT reorganization that we confirm biochemically. Moreover, unexpected similarity to binding of ANP32E and Swr1 with H2A.Z-H2B reveals that diverse H2A-H2B chaperones use common mechanisms of histone binding and regulating nucleosome functions. PMID:26455391

  19. FLYING-WATER Renewables-H2-H2O TERRAFORMING: PERMANENT Drought(s)-Elimination FOREVER!!!

    NASA Astrophysics Data System (ADS)

    Lyons, M.; Siegel, E.

    2010-03-01

    ``Water water everywhere; ne'er a drop to drink''[Coleridg(1798)]; now:``Hydrogen hydrogen everywhere;STILL ne'er a drop to drink'': ONLY H2 can be ``FLYING-WATER''/``chemical-rain-in-pipelines''/ ``Hindenberg-effect (H2-UP;H2O-DOWN): atomic-weights ratio: O/H2O=[16]/[18]˜90%; O already in air uphill; NO H2O pumping need! In water-starved glacial-melting world, rescue ONLY by Siegel[3rd Intl.Conf.Alt.Energy,Hemisphere/Springer(1980)- vol.5/ p.459]Renewables-H2-H2O purposely flexible versatile agile customizable scaleable retrofitable integrated operating- system. Rosenfeld[Sci.315,1396(3/9/2007)]-Biello[Sci.Am.(3/9/ 2007)]crucial geomorphology which ONLY maximal-buoyancy light- est-element H2 can exploit, to again make ``Mountains into Fount- ains": Siegel ``terra-forming''(and ocean-rebasificaton!!!) long pre-``Holdren''-``Ciccerine" ``geo-enginering'', only via Siegel proprietary magnetic-hydrogen-valve permits H2 flow in already in-ground dense BCC/ferritic-steels pipelines-network (NO new infrastructure) counters Tromp[Sci.300,1740(03)]global-pandemics (cancers/blindness/famine)dire-warning about H2-(ALONE)economy CATASTROPHIC H2 ozone-layer destruction sobering cavat to dangerous H2-automotion-economy panacea hype!

  20. Photochemical dehydrogenation of ethanol in dilute aqueous solution

    NASA Astrophysics Data System (ADS)

    Handman, J.; Harriman, A.; Porter, G.

    1984-02-01

    The cyclic photodissociation of water has not yet been achieved in a homogeneous solution using visible light. The replacement of the sacrificial electron donor with such waste materials as sulfide is suggested as a method for improving homogeneous systems. Attention is given to the efficient photogeneration of H2 by means of a system that employs a low grade fermentation product, aqueous ethanol, as electron donor. The photoproduction of H2 is coupled to the oxidation of the ethanol by means of NADH/alcohol dehydrogenase as a relay.

  1. HIST1H2AA — EDRN Public Portal

    Cancer.gov

    HIST1H2AA, a member of the histone 2A family, is a core component of the nucleosome. The nucleosome is a histone octamer containing two molecules each of H2A, H2B, H3 and H4 assembled in one H3-H4 heterotetramer and two H2A-H2B heterodimers. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template (the octamer wraps approximately 147 bp of DNA). Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling. The HIST1H2AA gene is intronless and encodes a member of the histone H2A family. Transcripts from this gene contain a palindromic termination element.

  2. Kansas Ethanol Lyons Approval

    EPA Pesticide Factsheets

    This update August 9, 2016 letter from EPA approves, with modifications, the petition from Kansas Ethanol, LLC, Lyons facility, regarding non-grandfathered ethanol produced through a dry mill process, qualifying under the Clean Air Act for renewable fuel

  3. Assay of H2O2 production by macrophages and neutrophils with homovanillic acid and horse-radish peroxidase.

    PubMed

    Ruch, W; Cooper, P H; Baggiolini, M

    1983-10-28

    A simple and sensitive method for measurement of the release of H2O2 from phagocytic cells is described. The assay is based on the H2O2-dependent oxidation of homovanillic acid (3-methoxy-4-hydroxyphenylacetic acid, HVA) to a highly fluorescent dimer (2,2'-dihydroxy-3,3'-dimethoxydiphenyl-5,5'-diacetic acid) which is mediated by horse-radish peroxidase. A linear relationship between fluorescence (lambda ex = 312 nm and lambda em = 420 nm) and amount of H2O2 was found in the range of 0.1-10 nmoles per 2.25 ml assay. The method was reliable for monitoring H2O2 production in large numbers of cell samples, as suspensions or monolayers, over periods of time extending between minutes and several hours. At concentrations optimal for detection of cellular release of H2O2, HVA and horse-radish peroxidase were devoid of cytotoxic effects. The time course of H2O2 release by mouse peritoneal and bone marrow-derived macrophages and by human neutrophils was determined following stimulation with zymosan particles or phorbol myristate acetate, and the dependence of H2O2 release on cell number and stimulus dosage was studied.

  4. Rewiring Lactococcus lactis for Ethanol Production

    PubMed Central

    Dehli, Tore; Jensen, Peter Ruhdal

    2013-01-01

    Lactic acid bacteria (LAB) are known for their high tolerance toward organic acids and alcohols (R. S. Gold, M. M. Meagher, R. Hutkins, and T. Conway, J. Ind. Microbiol. 10:45–54, 1992) and could potentially serve as platform organisms for production of these compounds. In this study, we attempted to redirect the metabolism of LAB model organism Lactococcus lactis toward ethanol production. Codon-optimized Zymomonas mobilis pyruvate decarboxylase (PDC) was introduced and expressed from synthetic promoters in different strain backgrounds. In the wild-type L. lactis strain MG1363 growing on glucose, only small amounts of ethanol were obtained after introducing PDC, probably due to a low native alcohol dehydrogenase activity. When the same strains were grown on maltose, ethanol was the major product and lesser amounts of lactate, formate, and acetate were formed. Inactivating the lactate dehydrogenase genes ldhX, ldhB, and ldh and introducing codon-optimized Z. mobilis alcohol dehydrogenase (ADHB) in addition to PDC resulted in high-yield ethanol formation when strains were grown on glucose, with only minor amounts of by-products formed. Finally, a strain with ethanol as the sole observed fermentation product was obtained by further inactivating the phosphotransacetylase (PTA) and the native alcohol dehydrogenase (ADHE). PMID:23377945

  5. Rewiring Lactococcus lactis for ethanol production.

    PubMed

    Solem, Christian; Dehli, Tore; Jensen, Peter Ruhdal

    2013-04-01

    Lactic acid bacteria (LAB) are known for their high tolerance toward organic acids and alcohols (R. S. Gold, M. M. Meagher, R. Hutkins, and T. Conway, J. Ind. Microbiol. 10:45-54, 1992) and could potentially serve as platform organisms for production of these compounds. In this study, we attempted to redirect the metabolism of LAB model organism Lactococcus lactis toward ethanol production. Codon-optimized Zymomonas mobilis pyruvate decarboxylase (PDC) was introduced and expressed from synthetic promoters in different strain backgrounds. In the wild-type L. lactis strain MG1363 growing on glucose, only small amounts of ethanol were obtained after introducing PDC, probably due to a low native alcohol dehydrogenase activity. When the same strains were grown on maltose, ethanol was the major product and lesser amounts of lactate, formate, and acetate were formed. Inactivating the lactate dehydrogenase genes ldhX, ldhB, and ldh and introducing codon-optimized Z. mobilis alcohol dehydrogenase (ADHB) in addition to PDC resulted in high-yield ethanol formation when strains were grown on glucose, with only minor amounts of by-products formed. Finally, a strain with ethanol as the sole observed fermentation product was obtained by further inactivating the phosphotransacetylase (PTA) and the native alcohol dehydrogenase (ADHE).

  6. Uptake and Reactions of Formaldehyde, Acetaldehyde, Acetone, Propanal and Ethanol in Sulfuric Acid solutions at 200-240 K: Implications for upper tropospheric aerosol composition

    NASA Astrophysics Data System (ADS)

    Iraci, L. T.; Williams, M. B.; Axson, J.; Michelsen, R.

    2007-12-01

    The production of light absorbing, organic material in aerosol that is normally considered to be transparent in the UV and visible wavelength regions has significant implications for biogeochemical cycling and climate modelling. Production mechanisms likely involve carbonyl compounds such as formaldehyde, acetone, acetaldehyde and propanal that are present in significant quantities in the upper troposphere (UT). In this study, we have performed experiments focusing on a class of acid catalyzed carbonyl reactions, the formation of acetals. R2C=O + 2R'OH --> R2C(OR')2 + H2O Using a Knudsen cell apparatus, we have measured the rate of uptake of formaldehyde, acetaldehyde, acetone, propanal, and ethanol into sulfuric acid solutions ranging between 40-70 wt% of acid, containing 0-0.1 M of ethanol, acetone or formaldehyde at temperatures of 220-250 K. For all reactant pairs, the aldol condensation path, including self reaction, should be insignificant at the acidities studied. Evidence for reaction between organics was observed for all pairs, except those involving propanal which were likely limited by the very low solubility. We attribute enhanced uptake to the formation of acetals, such as 1,1-diethoxyethane and 2,2- diethoxypropane, among others. Enhanced uptake was observed to proceed on timescales > 1 hour and sometimes shows complex dependence on acidity that is likely related to speciation of the individual carbonyls in acidic solution. The acetal products do not absorb in the visible but are less volatile than parent molecules, allowing for accumulation in sulfuric acid particles, and enhanced uptake. Cross reactions of carbonyls with alcohols in sulfuric acid medium have not been previously measured, yet methanol and ethanol show high solubility and are present at significant concentrations in the UT. Thus even at slow reaction rates, the acetal reaction has ample starting material and proceeds under conditions common to the UT. We will present results for the

  7. Removal of Boron in Silicon by H2-H2O Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Tang, Kai; Andersson, Stefan; Nordstrand, Erlend; Tangstad, Merete

    2012-08-01

    The removal of boron in pure silicon by gas mixtures has been examined in the laboratory. Water-vapor-saturated hydrogen was used to remove boron doped in electronic-grade silicon in a vacuum frequency furnace. Boron concentrations in silicon were reduced from 52 ppm initially to 0.7 ppm and 3.4 ppm at 1450°C and 1500°C, respectively, after blowing a H2-3.2%H2O gas mixture for 180 min. The experimental results indicate that the boron removal as a function of gas-blowing time follows the law of exponential decay. After 99% of the boron is removed, approximately 90% of the silicon can be recovered. In order to better understand the gaseous refining mechanism, the quantum chemical coupled cluster with single and double excitations and a perturbative treatment of triple excitations method was used to accurately predict the enthalpy and entropy of formation of the HBO molecule. A simple refining model was then used to describe the boron refining process. This model can be used to optimize the refining efficiency.

  8. Sum-frequency generation of acetate adsorption on Au and Pt surfaces: Molecular structure effects

    NASA Astrophysics Data System (ADS)

    Braunschweig, Björn; Mukherjee, Prabuddha; Kutz, Robert B.; Wieckowski, Andrzej; Dlott, Dana D.

    2010-12-01

    The reversible adsorption of acetate on polycrystalline Au and Pt surfaces was investigated with broadband sum-frequency generation (SFG) and cyclic voltammetry. Specifically adsorbed acetate as well as coadsorbed sulfuric acid anions are observed for the first time with SFG and give rise to dramatically different SFG intensities on Au and Pt surfaces. While similar coverages of acetate adlayers on Au and Pt surfaces are well established by previous studies, an identification of the interfacial molecular structure has been elusive. However, we have applied the high sensitivity of SFG for interfacial polar ordering to identify different acetate structures at Au and Pt surfaces in contact with HClO4 and H2SO4 electrolytes. Acetate competes with the formation of surface oxides and shifts the oxidation threshold of both Au and Pt electrodes anodically. Effects of the supporting electrolyte on the formation of acetate adlayers are revealed by comparing SFG spectra in HClO4 and H2SO4 solutions: Sulfuric acid anions modify the potential-dependent acetate adsorption, compete with adsorbed acetate on Au and coadsorb with acetate on Pt surfaces.

  9. Anaphylactoid reaction to ethanol.

    PubMed

    Kelso, J M; Keating, M U; Squillace, D L; O'Connell, E J; Yunginger, J W; Sachs, M I

    1990-05-01

    We studied a 14-year-old boy who developed a pruritic rash and facial swelling after ingestion of beer or wine. A blinded challenge with purified ethanol was positive demonstrating ethanol itself to be the offending agent. An IgE-mediated reaction to ethanol or one of its metabolites as a hapten is possible, or the reaction may involve unusual metabolism of ethanol with accumulation of acetaldehyde and/or direct mast cell degranulation.

  10. Histamine H2 receptor trafficking: role of arrestin, dynamin, and clathrin in histamine H2 receptor internalization.

    PubMed

    Fernandez, Natalia; Monczor, Federico; Baldi, Alberto; Davio, Carlos; Shayo, Carina

    2008-10-01

    Agonist-induced internalization of G protein-coupled receptors (GPCRs) has been implicated in receptor desensitization, resensitization, and down-regulation. In the present study, we sought to establish whether the histamine H2 receptor (H2r) agonist amthamine, besides promoting receptor desensitization, induced H2r internalization. We further studied the mechanisms involved and its potential role in receptor resensitization. In COS7 transfected cells, amthamine induced H2r time-dependent internalization, showing 70% of receptor endocytosis after 60-min exposure to amthamine. Agonist removal led to the rapid recovery of resensitized receptors to the cell surface. Similar results were obtained in the presence of cycloheximide, an inhibitor of protein synthesis. Treatment with okadaic acid, an inhibitor of the protein phosphatase 2A (PP2A) family of phosphatases, reduced the recovery of both H2r membrane sites and cAMP response. Arrestin 3 but not arrestin 2 overexpression reduced both H2r membrane sites and H2r-evoked cAMP response. Receptor cotransfection with dominant-negative mutants for arrestin, dynamin, Eps15 (a component of the clathrin-mediated endocytosis machinery), or RNA interference against arrestin 3 abolished both H2r internalization and resensitization. Similar results were obtained in U937 cells endogenously expressing H2r. Our findings suggest that amthamine-induced H2r internalization is crucial for H2r resensitization, processes independent of H2r de novo synthesis but dependent on PP2A-mediated dephosphorylation. Although we do not provide direct evidence for H2r interaction with beta-arrestin, dynamin, and/or clathrin, our results support their involvement in H2r endocytosis. The rapid receptor recycling to the cell surface and the specific involvement of arrestin 3 in receptor internalization further suggest that the H2r belongs to class A GPCRs.

  11. Improved quasi-unary nucleation model for binary H2SO4-H2O homogeneous nucleation

    NASA Astrophysics Data System (ADS)

    Yu, Fangqun

    2007-08-01

    Aerosol nucleation events have been observed at a variety of locations worldwide, and may have significant climatic and health implications. Binary homogeneous nucleation (BHN) of H2SO4 and H2O is the foundation of recently proposed nucleation mechanisms involving additional species such as ammonia, ions, and organic compounds, and it may dominate atmospheric nucleation under certain conditions. We have shown in previous work that H2SO4-H2O BHN can be treated as a quasi-unary nucleation (QUN) process involving H2SO4 in equilibrium with H2O vapor, and we have developed a self-consistent kinetic model for H2SO4-H2O nucleation. Here, the QUN approach is improved, and an analytical expression yielding H2SO4-H2O QUN rates is derived. Two independent measurements related to monomer hydration are used to constrain the equilibrium constants for this process, which reduces a major source of uncertainty. It is also shown that the capillarity approximation may lead to a large error in the calculated Gibbs free energy change for the evaporation of H2SO4 molecules from small H2SO4-H2O clusters, which affects the accuracy of predicted BHN nucleation rates. The improved QUN model—taking into account the recently measured energetics of small clusters—is thermodynamically more robust. Moreover, predicted QUN nucleation rates are in better agreement with available experimental data than rates calculated using classical H2SO4-H2O BHN theory.

  12. FLYING-WATER Renewables-H2-H2O TERRAFORMING: PERMANENT ETERNAL Drought(s)-Elimination FOREVER!!!

    NASA Astrophysics Data System (ADS)

    Wignall, J.; Lyons, Marv; Ertl, G.; Alefeld, Georg; Youdelis, W.; Radd, H.; Oertle, G.; Siegel, Edward

    2013-03-01

    ''H2O H2O everywhere; ne'er a drop to drink''[Coleridge(1798)] now: ''H2 H2 everywhere; STILL ne'er a drop to drink'': ONLY H2 (or methane CH4) can be FLYING-WATER(F-W) chemical-rain-in-pipelines Hindenberg-effect (H2-UP;H2O-DOWN): { ∖{}O/H2O{ ∖}} =[16]/[18] ∖sim 90{ ∖%} O already in air uphill; NO H2O pumping need! In global-warming driven H2O-starved glacial-melting world, rescue is possible ONLY by Siegel [ ∖underline {3rd Intl. Conf. Alt.-Energy }(1980)-vol.5/p.459!!!] Renewables-H2-H2O purposely flexible versatile agile customizable scaleable retrofitable integrated operating-system. Rosenfeld[Science 315,1396(3/9/2007)]-Biello [Sci.Am.(3/9 /2007)] crucial geomorphology which ONLY maximal-buoyancy H2 can exploit, to again make ''Mountains into Fountains'', ``upthrust rocks trapping the clouds to precipitate their rain/snow/H2O'': ''terraforming''(and ocean-rebasificaton!!!) ONLY VIA Siegel[APS March MTGS.:1960s-2000ss) DIFFUSIVE-MAGNETORESISTANCE (DMR) proprietary MAGNETIC-HYDROGEN-VALVE(MHV) ALL-IMPORTANT PRECLUDED RADIAL-diffusion, permitting ONLY AXIAL-H2-BALLISTIC-flow (``G.A''.''/DoE''/''Terrapower''/''Intellectual-Ventures''/ ''Gileland''/ ''Myhrvold''/''Gates'' ``ARCHIMEDES'') in ALREADY IN-ground dense BCC/ferritic-steels pipelines-network (NO new infrastructure) counters Tromp[Science 300,1740(2003)] dire warning of global-pandemics (cancers/ blindness/ famine)

  13. Improvement of acetic acid tolerance of Saccharomyces cerevisiae using a zinc-finger-based artificial transcription factor and identification of novel genes involved in acetic acid tolerance.

    PubMed

    Ma, Cui; Wei, Xiaowen; Sun, Cuihuan; Zhang, Fei; Xu, Jianren; Zhao, Xinqing; Bai, Fengwu

    2015-03-01

    Acetic acid is present in cellulosic hydrolysate as a potent inhibitor, and the superior acetic acid tolerance of Saccharomyces cerevisiae ensures good cell viability and efficient ethanol production when cellulosic raw materials are used as substrates. In this study, a mutant strain of S. cerevisiae ATCC4126 (Sc4126-M01) with improved acetic acid tolerance was obtained through screening strains transformed with an artificial zinc finger protein transcription factor (ZFP-TF) library. Further analysis indicated that improved acetic acid tolerance was associated with improved catalase (CAT) activity. The ZFP coding sequence associated with the improved phenotype was identified, and real-time RT-PCR analysis revealed that three of the possible genes involved in the enhanced acetic acid tolerance regulated by this ZFP-TF, namely YFL040W, QDR3, and IKS1, showed decreased transcription levels in Sc4126-M01 in the presence of acetic acid, compared to those in the control strain. Sc4126-M01 mutants having QDR3 and IKS1 deletion (ΔQDR3 and ΔIKS1) exhibited higher acetic acid tolerance than the wild-type strain under acetic acid treatment. Glucose consumption rate and ethanol productivity in the presence of 5 g/L acetic acid were improved in the ΔQDR3 mutant compared to the wild-type strain. Our studies demonstrated that the synthetic ZFP-TF library can be used to improve acetic acid tolerance of S. cerevisiae and that the employment of an artificial transcription factor can facilitate the exploration of novel functional genes involved in stress tolerance of S. cerevisiae.

  14. Acetate Kinase Isozymes Confer Robustness in Acetate Metabolism

    PubMed Central

    Chan, Siu Hung Joshua; Nørregaard, Lasse; Solem, Christian; Jensen, Peter Ruhdal

    2014-01-01

    Acetate kinase (ACK) (EC no: 2.7.2.1) interconverts acetyl-phosphate and acetate to either catabolize or synthesize acetyl-CoA dependent on the metabolic requirement. Among all ACK entries available in UniProt, we found that around 45% are multiple ACKs in some organisms including more than 300 species but surprisingly, little work has been done to clarify whether this has any significance. In an attempt to gain further insight we have studied the two ACKs (AckA1, AckA2) encoded by two neighboring genes conserved in Lactococcus lactis (L. lactis) by analyzing protein sequences, characterizing transcription structure, determining enzyme characteristics and effect on growth physiology. The results show that the two ACKs are most likely individually transcribed. AckA1 has a much higher turnover number and AckA2 has a much higher affinity for acetate in vitro. Consistently, growth experiments of mutant strains reveal that AckA1 has a higher capacity for acetate production which allows faster growth in an environment with high acetate concentration. Meanwhile, AckA2 is important for fast acetate-dependent growth at low concentration of acetate. The results demonstrate that the two ACKs have complementary physiological roles in L. lactis to maintain a robust acetate metabolism for fast growth at different extracellular acetate concentrations. The existence of ACK isozymes may reflect a common evolutionary strategy in bacteria in an environment with varying concentrations of acetate. PMID:24638105

  15. Separate hydrolysis and fermentation (SHF) of Prosopis juliflora, a woody substrate, for the production of cellulosic ethanol by Saccharomyces cerevisiae and Pichia stipitis-NCIM 3498.

    PubMed

    Gupta, Rishi; Sharma, Krishna Kant; Kuhad, Ramesh Chander

    2009-02-01

    Prosopis juliflora (Mesquite) is a raw material for long-term sustainable production of cellulosics ethanol. In this study, we used acid pretreatment, delignification and enzymatic hydrolysis to evaluate the pretreatment to produce more sugar, to be fermented to ethanol. Dilute H(2)SO(4) (3.0%,v/v) treatment resulted in hydrolysis of hemicelluloses from lignocellulosic complex to pentose sugars along with other byproducts such as furfural, hydroxymethyl furfural (HMF), phenolics and acetic acid. The acid pretreated substrate was delignified to the extent of 93.2% by the combined action of sodium sulphite (5.0%,w/v) and sodium chlorite (3.0%,w/v). The remaining cellulosic residue was enzymatically hydrolyzed in 0.05 M citrate phosphate buffer (pH 5.0) using 3.0 U of filter paper cellulase (FPase) and 9.0 U of beta-glucosidase per mL of citrate phosphate buffer. The maximum enzymatic saccharification of cellulosic material (82.8%) was achieved after 28 h incubation at 50 degrees C. The fermentation of both acid and enzymatic hydrolysates, containing 18.24 g/L and 37.47 g/L sugars, with Pichia stipitis and Saccharomyces cerevisiae produced 7.13 g/L and 18.52 g/L of ethanol with corresponding yield of 0.39 g/g and 0.49 g/g, respectively.

  16. Ethanol Basics (Fact Sheet)

    SciTech Connect

    Not Available

    2015-01-01

    Ethanol is a widely-used, domestically-produced renewable fuel made from corn and other plant materials. More than 96% of gasoline sold in the United States contains ethanol. Learn more about this alternative fuel in the Ethanol Basics Fact Sheet, produced by the U.S. Department of Energy's Clean Cities program.

  17. The N-terminal tails of the H2A-H2B histones affect dimer structure and stability.

    PubMed

    Placek, Brandon J; Gloss, Lisa M

    2002-12-17

    The histone proteins of the core nucleosome are highly basic and form heterodimers in a "handshake motif." The N-terminal tails of the histones extend beyond the canonical histone fold of the hand-shake motif and are the sites of posttranslational modifications, including lysine acetylations and serine phosphorylations, which influence chromatin structure and activity as well as alter the charge state of the tails. However, it is not well understood if these modifications are signals for recruitment of other cellular factors or if the removal of net positive charge from the N-terminal tail plays a role in the overall structure of chromatin. To elucidate the effects of the N-terminal tails on the structure and stability of histones, the highly charged N-terminal tails were truncated from the H2A and H2B histones. Three mutant dimers were studied: DeltaN-H2A/WT H2B; WT H2A/DeltaN-H2B, and DeltaN-H2A/DeltaN-H2B. The CD spectra, stabilities to urea-denaturation, and the salt-dependent stabilization of the three truncated dimers were compared with those of the wild-type dimer. The data support four conclusions regarding the effects of the N-terminal tails of H2A and H2B: (1) Removal of the N-terminal tails of H2A and H2B enhance the helical structure of the mutant heterodimers. (2) Relative to the full-length WT heterodimer, the DeltaN-H2A/WT H2B dimer is destabilized, while the WT H2A/DeltaN-H2B and DeltaN-H2A/DeltaN-H2B dimers are slightly stabilized. (3) The truncated dimers exhibit decreased m values, relative to the WT dimer, supporting the hypothesis that the N-terminal tails in the isolated dimer adopt a collapsed structure. (4) Electrostatic repulsion in the N-terminal tails decreases the stability of the H2A-H2B dimer.

  18. Detection of absorption by H2 in molecular clouds: A direct measurement of the H2:CO ratio

    NASA Technical Reports Server (NTRS)

    Lacy, J. H.; Knacke, R.; Geballe, T. R.; Tokunaga, A. T.

    1994-01-01

    Vibrational absorption by H2 and CO has been searched for toward infrared sources embedded in molecular clouds. H2 was detected toward NGC 2024 IRS 2 and possibly toward NGC 2264 (GL 989). CO was detected toward both sources. The results are consistent with the H2 ortho:para ratio being equilibrated at the cloud temperature. Toward NGC 2024, H2:CO = (3700(sub -2600)(sup +3100)) (2 sigma limits), and toward NGC 2264, H2:CO less than 6000. Approximately one-third of all carbon is in gas-phase CO.

  19. [Room-temperature solid-state synthesis of complexes of copper acetate and multi-nitrogen heterocyclic ligands].

    PubMed

    Shi, Xu-hua; Li, Dan; Feng, Qiao; Huang, Qing-lian; Xu, Yan-ping

    2003-06-01

    At room temperature, sufficiently grinding the mixtures of copper acetate with 1,2,4-triazole and benzotriazole separately resulted in the proceeding of the solid state reaction. It was found that the acetate acid flowed during the grinding. The heterocycle ligand 1,2,4-triazole or benzotriazole replaced the acetate and coordinates to Cu (II) to form a mixed ligands complex. The elementary analysis results show that the compositions of products were consistent with Cu (C2H2N3)(Ac).H2O and Cu (C6H4N3)(Ac).H2O, respectively. Infrared spectra of both complexes have exhibited the characteristics of C=N vibrations [Cu(C2H2N3)(Ac).H2O, 1,513 cm-1; Cu(C6H4N3)(Ac).H2O, 1,446 cm-1] for heterocycle ligands, C=O [Cu(C2H2N3)(Ac).H2O, 1,570 and 1,406 cm-1; Cu(C6H4N3)(Ac).H2O, 1,604 and 1,422 cm-1] for acetate and O-H (-3,400 cm-1) for water, respectively. The solid state reaction provides a way which is rapid, mild and in the absence of solvent for synthesized new complexes.

  20. Hydrogen polysulfide (H2S n ) signaling along with hydrogen sulfide (H2S) and nitric oxide (NO).

    PubMed

    Kimura, Hideo

    2016-11-01

    Hydrogen sulfide (H2S) is a physiological mediator with various roles, including neuro-modulation, vascular tone regulation, and cytoprotection against ischemia-reperfusion injury, angiogenesis, and oxygen sensing. Hydrogen polysulfide (H2S n ), which possesses a higher number of sulfur atoms than H2S, recently emerged as a potential signaling molecule that regulates the activity of ion channels, a tumor suppressor, transcription factors, and protein kinases. Some of the previously reported effects of H2S are now attributed to the more potent H2S n . H2S n is produced by 3-mercaptopyruvate sulfurtransferase (3MST) from 3-mercaptopyruvate (3MP) and is generated by the chemical interaction of H2S with nitric oxide (NO). H2S n sulfhydrates (sulfurates) cysteine residues of target proteins and modifies their activity, whereas H2S sulfurates oxidized cysteine residues as well as reduces cysteine disulfide bonds. This review focuses on the recent progress made in studies concerning the production and physiological roles of H2S n and H2S.

  1. Lipid-enhanced ethanol production from xylose by Pachysolen tannophilus

    SciTech Connect

    Dekker, R.F.H.

    1986-04-01

    A number of different yeasts are now recognized as being capable of fermenting the pentose sugar, D-xylose, into ethanol. The most prominent among these are Pachysolen tannophilus and several Candida species. D-Xylose is found principally in lignocellulosic materials where it occurs as the main constitutent of the hemicellulosic xylans (1,4-..beta..-D-heteroxylans). With the exception of Candida XF-217, the conversion yields of xylose into ethanol for most yeasts were generally low (less than 70% of theoretical when grown on at least 50 g/l xylose). The low ethanol yields are attributable to a number of factors: 1) fermentation was not performed under conditions that maximize ethanol formation; 2) ethanol was not the major fermentation end-product, (e.g., acetic acid xylitol, and arabinitol are also known products, 3) ethanol toxicity; 4) ethanol is assimilated when the substrate becomes limiting; 4.8 and 5) osmotic sensitivity to high substrate levels, i.e. substrate inhibition. Attempts to increase ethanol yields of yeasts by adding exogenous lipids (e.g., oleic and linoleic acids, or ergosterol or its ester, lipid mixtures, or protein-lipid mixtures) to nutrient medium have succeeded in improving ethanol yields and also in reducing fermentation times. These lipids, when added to the nutrient medium, were incorporated into the yeast's cellular membrane. The protective action of these lipids was to alleviate the inhibitory effect of ethanol which then allowed the cells to tolerate higher ethanol levels. This communication reports on improved ethanol yields arising from the fermentation of xylose by a Pachysolen tannophilus strain when grown semi-aerobically in the presence of exogenous-added lipids. 17 references.

  2. The role of H2O in the Saturn ionosphere

    NASA Astrophysics Data System (ADS)

    Shemansky, Donald; Liu, Xianming

    2010-05-01

    Stellar occultations in the Cassini Ultraviolet Imaging Spectrograph Experiment observation program have provided measurements of the vertical profiles of H2 and and minor components of the atmosphere. The minor species identified and measured in the extinction spectra to date are CH4, C2H2, and C2H4. Measurements of abundance profiles are reported here, with limits on H2O content. The focus of this paper is on H2O because of the importance of this species to the understanding of upper atmospheric physical chemistry with significant consequences for ionospheric properties and energy budget. Ionospheric theory published in several papers beginning as early as 1984 have a common critical dependence on a sufficiently large H2O mixing ratio to control the lifetime of the assumed dominant ion, H+. The vertical extinction profiles, which extend down to an impact parameter of 300 km above the 1 bar pressure level, show no evidence of H2O in the spectrum at mid and low latitudes, establishing a mixing ratio [H2O]/[H2] ≤ 4 × 10-8, compatible with earlier global average measurements. The upper limit on H2O abundance at mid latitude establishes a mixing ratio more an order of magnitude too low to influence the ionosphere population in competition with calculated H+ + H2 X(v:J) charge capture reaction rates. The analysis of the extinction spectra produces densities and mixing ratios of the observed species and these results are reported and discussed.

  3. Working with "H2S": facts and apparent artifacts.

    PubMed

    Wedmann, Rudolf; Bertlein, Sarah; Macinkovic, Igor; Böltz, Sebastian; Miljkovic, Jan Lj; Muñoz, Luis E; Herrmann, Martin; Filipovic, Milos R

    2014-09-15

    Hydrogen sulfide (H2S) is an important signaling molecule with physiological endpoints similar to those of nitric oxide (NO). Growing interest in its physiological roles and pharmacological potential has led to large sets of contradictory data. The principle cause of these discrepancies can be the common neglect of some of the basic H2S chemistry. This study investigates how the experimental outcome when working with H2S depends on its source and dose and the methodology employed. We show that commercially available NaHS should be avoided and that traces of metal ions should be removed because these can reduce intramolecular disulfides and change protein structure. Furthermore, high H2S concentrations may lead to a complete inhibition of cell respiration, mitochondrial membrane potential depolarization and superoxide generation, which should be considered when discussing the biological effects observed upon treatment with high concentrations of H2S. In addition, we provide chemical evidence that H2S can directly react with superoxide. H2S is also capable of reducing cytochrome c(3+) with the concomitant formation of superoxide. H2S does not directly react with nitrite but with NO electrodes that detect H2S. In addition, H2S interferes with the Griess reaction and should therefore be removed from the solution by Cd(2+) or Zn(2+) precipitation prior to nitrite quantification. 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) is reduced by H2S, and its use should be avoided in combination with H2S. All these constraints must be taken into account when working with H2S to ensure valid data.

  4. Efficient production of ethanol from waste paper and the biochemical methane potential of stillage eluted from ethanol fermentation.

    PubMed

    Nishimura, Hiroto; Tan, Li; Sun, Zhao-Yong; Tang, Yue-Qin; Kida, Kenji; Morimura, Shigeru

    2016-02-01

    Waste paper can serve as a feedstock for ethanol production due to being rich in cellulose and not requiring energy-intensive thermophysical pretreatment. In this study, an efficient process was developed to convert waste paper to ethanol. To accelerate enzymatic saccharification, pH of waste paper slurry was adjusted to 4.5-5.0 with H2SO4. Presaccharification and simultaneous saccharification and fermentation (PSSF) with enzyme loading of 40 FPU/g waste paper achieved an ethanol yield of 91.8% and productivity of 0.53g/(Lh) with an ethanol concentration of 32g/L. Fed-batch PSSF was used to decrease enzyme loading to 13 FPU/g waste paper by feeding two separate batches of waste paper slurry. Feeding with 20% w/w waste paper slurry increased ethanol concentration to 41.8g/L while ethanol yield decreased to 83.8%. To improve the ethanol yield, presaccharification was done prior to feeding and resulted in a higher ethanol concentration of 45.3g/L, a yield of 90.8%, and productivity of 0.54g/(Lh). Ethanol fermentation recovered 33.2% of the energy in waste paper as ethanol. The biochemical methane potential of the stillage eluted from ethanol fermentation was 270.5mL/g VTS and 73.0% of the energy in the stillage was recovered as methane. Integrating ethanol fermentation with methane fermentation, recovered a total of 80.4% of the energy in waste paper as ethanol and methane.

  5. L-Lactic acid production from glycerol coupled with acetic acid metabolism by Enterococcus faecalis without carbon loss.

    PubMed

    Murakami, Nao; Oba, Mana; Iwamoto, Mariko; Tashiro, Yukihiro; Noguchi, Takuya; Bonkohara, Kaori; Abdel-Rahman, Mohamed Ali; Zendo, Takeshi; Shimoda, Mitsuya; Sakai, Kenji; Sonomoto, Kenji

    2016-01-01

    Glycerol is a by-product in the biodiesel production process and considered as one of the prospective carbon sources for microbial fermentation including lactic acid fermentation, which has received considerable interest due to its potential application. Enterococcus faecalis isolated in our laboratory produced optically pure L-lactic acid from glycerol in the presence of acetic acid. Gas chromatography-mass spectrometry analysis using [1, 2-(13)C2] acetic acid proved that the E. faecalis strain QU 11 was capable of converting acetic acid to ethanol during lactic acid fermentation of glycerol. This indicated that strain QU 11 restored the redox balance by oxidizing excess NADH though acetic acid metabolism, during ethanol production, which resulted in lactic acid production from glycerol. The effects of pH control and substrate concentration on lactic acid fermentation were also investigated. Glycerol and acetic acid concentrations of 30 g/L and 10 g/L, respectively, were expected to be appropriate for lactic acid fermentation of glycerol by strain QU 11 at a pH of 6.5. Furthermore, fed-batch fermentation with 30 g/L glycerol and 10 g/L acetic acid wholly exhibited the best performance including lactic acid production (55.3 g/L), lactic acid yield (0.991 mol-lactic acid/mol-glycerol), total yield [1.08 mol-(lactic acid and ethanol)]/mol-(glycerol and acetic acid)], and total carbon yield [1.06 C-mol-(lactic acid and ethanol)/C-mol-(glycerol and acetic acid)] of lactic acid and ethanol. In summary, the strain QU 11 successfully produced lactic acid from glycerol with acetic acid metabolism, and an efficient fermentation system was established without carbon loss.

  6. Morphology of collisional nonlinear spectra in H2-Kr and H2-Xe mixtures.

    PubMed

    Głaz, Waldemar; Bancewicz, Tadeusz; Godet, Jean-Luc; Maroulis, George; Haskopoulos, Anastasios

    2013-03-28

    This article reports new results of theoretical and numerical studies of spectral features of the collision-induced hyper-Rayleigh light scattered in dihydrogen-noble gas (H2-Rg) mixtures. The most massive and polarizable scattering supermolecules with Rg = Kr and Xe have been added to the previously considered systems in order to gain a more complete insight into the evolution of the spectral properties. The symmetry adapted components of the first collisional hyperpolarizabilities are obtained by means of the quantum chemistry numerical routines supplemented with appropriate theoretical methods. Roto-translational spectral lines are calculated on the grounds of the quantum-mechanical as well as semi-classical approach. The role of particular hyperpolarizability components in forming the line shapes is discussed. The intensities of the lines are compared with those obtained for less massive scatterers. Advantages of prospective application of the new scattering systems for experimental detection of the nonlinear collisional effects are indicated.

  7. Quantum chemical study of ternary mixtures of: HNO3:H2SO4:H2O

    NASA Astrophysics Data System (ADS)

    Verdes, M. A.; Gómez, P. C.; Gálvez, O.

    2009-04-01

    Water, nitric acid and sulfuric acid are important atmospheric species as individual species and as hydrogen-bonded aggregates involved in many physical-chemical processes both superficial and bulk. The importance of heterogeneous chemical reactions taking place on ice surfaces, either solid water or solid water plus nitric or sulfuric acid, is well established now in relation to the ozone-depleting mechanisms. Also the importance of liquid droplets formed by HNO3.H2SO4.H2O as components of PSC was soon recognized [1-3]. Finally the physical properties of finely divided aqueous systems is an interesting and active field of research in which theoretical information on the microphysical domain systems may help to understand and rationalize the wealth of experimental information. This can also be the initial step in the study of more complex mixtures with higher amounts of water or variable proportions of their constituents. This kind of calculations have been successfully performed in the past[4]. We present here our results on the structure and spectroscopic and thermodynamic properties of the energy-lowest lying structures among those thermodynamically stable formed by linking the acids plus water. The calculations have been carried out by means of DFT methods (in particular the successful B3LYP) using different basis sets that contain appropriate sets of polarization and diffuse functions up to quadruple-Z quality (Dunninǵs aug-cc-pVQZ). Careful assessment of the dependability of the methodology used has been carried out. This work has been supported by the Spanish Ministry of Education, Projects FIS2007-61686 and CTQ2008-02578/BQU References: [1] Carslaw, K. S. et al.: Geophys. Res. Lett. 21, 2479-2482, 1994 [2] Drdla, K. Et al. :Geophys. Res. Lett. 21, 2473-2478, 1994 [3] Tabazadeh, A. et al.: Geophys. Res. Lett 21, 1619-1622, 1994 [4] Escribano, R et al.: J. J. Chem. Phys A 2003, 107, 652.

  8. Effects of Oxygen Availability on Acetic Acid Tolerance and Intracellular pH in Dekkera bruxellensis

    PubMed Central

    Capusoni, Claudia; Arioli, Stefania; Zambelli, Paolo; Moktaduzzaman, M.; Mora, Diego

    2016-01-01

    ABSTRACT The yeast Dekkera bruxellensis, associated with wine and beer production, has recently received attention, because its high ethanol and acid tolerance enables it to compete with Saccharomyces cerevisiae in distilleries that produce fuel ethanol. We investigated how different cultivation conditions affect the acetic acid tolerance of D. bruxellensis. We analyzed the ability of two strains (CBS 98 and CBS 4482) exhibiting different degrees of tolerance to grow in the presence of acetic acid under aerobic and oxygen-limited conditions. We found that the concomitant presence of acetic acid and oxygen had a negative effect on D. bruxellensis growth. In contrast, incubation under oxygen-limited conditions resulted in reproducible growth kinetics that exhibited a shorter adaptive phase and higher growth rates than those with cultivation under aerobic conditions. This positive effect was more pronounced in CBS 98, the more-sensitive strain. Cultivation of CBS 98 cells under oxygen-limited conditions improved their ability to restore their intracellular pH upon acetic acid exposure and to reduce the oxidative damage to intracellular macromolecules caused by the presence of acetic acid. This study reveals an important role of oxidative stress in acetic acid tolerance in D. bruxellensis, indicating that reduced oxygen availability can protect against the damage caused by the presence of acetic acid. This aspect is important for optimizing industrial processes performed in the presence of acetic acid. IMPORTANCE This study reveals an important role of oxidative stress in acetic acid tolerance in D. bruxellensis, indicating that reduced oxygen availability can have a protective role against the damage caused by the presence of acetic acid. This aspect is important for the optimization of industrial processes performed in the presence of acetic acid. PMID:27235432

  9. Kallolide A acetate pyrazoline.

    PubMed

    Rodríguez-Escudero, Idaliz; Marrero, Jeffrey; Rodríguez, Abimael D

    2012-01-01

    IN THE CRYSTAL STRUCTURE OF KALLOLIDE A ACETATE PYRAZOLINE [SYSTEMATIC NAME: 7-methyl-16-oxo-4,10-bis-(prop-1-en-2-yl)-17,18-dioxa-14,15-diaza-tetra-cyclo-[9.4.2.1(6,9).0(1,12)]octa-deca-6,8,14-trien-5-yl acetate], C(23)H(28)N(2)O(5), there is a 12-member-ed carbon macrocyclic structure. In addition, there is a tris-ubstituted furan ring, an approximately planar γ-lactone ring [maximum deviation of 0.057 (3) Å] and a pyraz-oline ring, the latter in an envelope conformation. The pyrazoline and the γ-lactone rings are fused in a cis configuration. In the crystal, mol-ecules are linked by weak C-H⋯O inter-actions, forming a two-dimensional network parallel to (001). An intra-molecular C-H⋯O hydrogen bond is also present.

  10. Kallolide A acetate pyrazoline

    PubMed Central

    Rodríguez-Escudero, Idaliz; Marrero, Jeffrey; Rodríguez, Abimael D.

    2012-01-01

    In the crystal structure of kallolide A acetate pyrazoline [systematic name: 7-methyl-16-oxo-4,10-bis­(prop-1-en-2-yl)-17,18-dioxa-14,15-diaza­tetra­cyclo­[9.4.2.16,9.01,12]octa­deca-6,8,14-trien-5-yl acetate], C23H28N2O5, there is a 12-member­ed carbon macrocyclic structure. In addition, there is a tris­ubstituted furan ring, an approximately planar γ-lactone ring [maximum deviation of 0.057 (3) Å] and a pyraz­oline ring, the latter in an envelope conformation. The pyrazoline and the γ-lactone rings are fused in a cis configuration. In the crystal, mol­ecules are linked by weak C—H⋯O inter­actions, forming a two-dimensional network parallel to (001). An intra­molecular C—H⋯O hydrogen bond is also present. PMID:22259545

  11. Diversification of histone H2A variants during plant evolution.

    PubMed

    Kawashima, Tomokazu; Lorković, Zdravko J; Nishihama, Ryuichi; Ishizaki, Kimitsune; Axelsson, Elin; Yelagandula, Ramesh; Kohchi, Takayuki; Berger, Frederic

    2015-07-01

    Among eukaryotes, the four core histones show an extremely high conservation of their structure and form nucleosomes that compact, protect, and regulate access to genetic information. Nevertheless, in multicellular eukaryotes the two families, histone H2A and histone H3, have diversified significantly in key residues. We present a phylogenetic analysis across the green plant lineage that reveals an early diversification of the H2A family in unicellular green algae and remarkable expansions of H2A variants in flowering plants. We define motifs and domains that differentiate plant H2A proteins into distinct variant classes. In non-flowering land plants, we identify a new class of H2A variants and propose their possible role in the emergence of the H2A.W variant class in flowering plants.

  12. A potential energy surface for the process H2 + H2O yielding H + H + H2O - Ab initio calculations and analytical representation

    NASA Technical Reports Server (NTRS)

    Schwenke, David W.; Walch, Stephen P.; Taylor, Peter R.

    1991-01-01

    Extensive ab initio calculations on the ground state potential energy surface of H2 + H2O were performed using a large contracted Gaussian basis set and a high level of correlation treatment. An analytical representation of the potential energy surface was then obtained which reproduces the calculated energies with an overall root-mean-square error of only 0.64 mEh. The analytic representation explicitly includes all nine internal degrees of freedom and is also well behaved as the H2 dissociates; it thus can be used to study collision-induced dissociation or recombination of H2. The strategy used to minimize the number of energy calculations is discussed, as well as other advantages of the present method for determining the analytical representation.

  13. Relaxation of H2O from its |04>- vibrational state in collisions with H2O, Ar, H2, N2, and O2

    NASA Astrophysics Data System (ADS)

    Barnes, Peter W.; Sims, Ian R.; Smith, Ian W. M.

    2004-03-01

    We report rate coefficients at 293 K for the collisional relaxation of H2O molecules from the highly excited |04>± vibrational states in collisions with H2O, Ar, H2, N2, and O2. In our experiments, the |04>- state is populated by direct absorption of radiation from a pulsed dye laser tuned to ˜719 nm. Evolution of the population in the (|04>±) levels is observed using the combination of a frequency-quadrupled Nd:YAG laser, which selectively photolyses H2O(|04>±), and a frequency-doubled dye laser, which observes the OH(v=0) produced by photodissociation via laser-induced fluorescence. The delay between the pulse from the pump laser and those from the photolysis and probe lasers was systematically varied to generate kinetic decays. The rate coefficients for relaxation of H2O(|04>±) obtained from these experiments, in units of cm3 molecule-1 s-1, are: k(H2O)=(4.1±1.2)×10-10, k(Ar)=(4.9±1.1)×10-12, k(H2)=(6.8±1.1)×10-12, k(N2)=(7.7±1.5)×10-12, k(O2)=(6.7±1.4)×10-12. The implications of these results for our previous reports of rate constants for the removal of H2O molecules in selected vibrational states by collisions with H atoms (P. W. Barnes et al., Faraday Discuss. Chem. Soc. 113, 167 (1999) and P. W. Barnes et al., J. Chem. Phys. 115, 4586 (2001).) are fully discussed.

  14. Relaxation of H2O from its /04>- vibrational state in collisions with H2O, Ar, H2, N2, and O2.

    PubMed

    Barnes, Peter W; Sims, Ian R; Smith, Ian W M

    2004-03-22

    We report rate coefficients at 293 K for the collisional relaxation of H2O molecules from the highly excited /04>(+/-) vibrational states in collisions with H2O, Ar, H2, N2, and O2. In our experiments, the mid R:04(-) state is populated by direct absorption of radiation from a pulsed dye laser tuned to approximately 719 nm. Evolution of the population in the (/04>(+/-)) levels is observed using the combination of a frequency-quadrupled Nd:YAG laser, which selectively photolyses H2O(/04>(+/-)), and a frequency-doubled dye laser, which observes the OH(v=0) produced by photodissociation via laser-induced fluorescence. The delay between the pulse from the pump laser and those from the photolysis and probe lasers was systematically varied to generate kinetic decays. The rate coefficients for relaxation of H2O(/04>(+/-)) obtained from these experiments, in units of cm3 molecule(-1) s(-1), are: k(H2O)=(4.1+/-1.2) x 10(-10), k(Ar)=(4.9+/-1.1) x 10(-12), k(H2)=(6.8+/-1.1) x 10(-12), k(N2)=(7.7+/-1.5) x 10(-12), k(O2)=(6.7+/-1.4) x 10(-12). The implications of these results for our previous reports of rate constants for the removal of H2O molecules in selected vibrational states by collisions with H atoms (P. W. Barnes et al., Faraday Discuss. Chem. Soc. 113, 167 (1999) and P. W. Barnes et al., J. Chem. Phys. 115, 4586 (2001).) are fully discussed.

  15. Influence of the presence of Zymomonas anaerobia on the conversion of cellobiose, glucose, and xylose to ethanol by Clostridium saccharolyticum

    SciTech Connect

    Asther, M.; Khan, A.W.

    1984-01-01

    To convert sugar mixtures containing cellobiose, glucose, and xylose to ethanol in a single step, the possibility of using a coculture consisting of Clostridium saccharolyticum and Zymomonas anaerobia was studied. In monoculture, C. saccharolyticum utilized all three sugars; however, it preferentially utilized glucose and produced acetic acid in addition to ethanol. The formation of acetic acid from the metabolism of glucose inhibited the growth of C. saccharolyticum and, consequently, the utilization of cellobiose and xylose. In monoculture, Z. anaerobia utilized glucose at a rate of 50 g/L day, but it did not ferment cellobiose or xylose. In coculture, Z. anaerobia converted most of the glucose to ethanol during the lag phase of growth of C. saccharolyticum, which then converted cellobiose and xylose to ethanol. The use of this coculture increased both the rate and the efficiency of the conversion of these three sugars to ethanol, and produced relatively small amounts of acetic acid.

  16. Nucleosome adaptability conferred by sequence and structural variations in histone H2A-H2B dimers.

    PubMed

    Shaytan, Alexey K; Landsman, David; Panchenko, Anna R

    2015-06-01

    Nucleosome variability is essential for their functions in compacting the chromatin structure and regulation of transcription, replication and cell reprogramming. The DNA molecule in nucleosomes is wrapped around an octamer composed of four types of core histones (H3, H4, H2A, H2B). Nucleosomes represent dynamic entities and may change their conformation, stability and binding properties by employing different sets of histone variants or by becoming post-translationally modified. There are many variants of histones H2A and H2B. Specific H2A and H2B variants may preferentially associate with each other resulting in different combinations of variants and leading to the increased combinatorial complexity of nucleosomes. In addition, the H2A-H2B dimer can be recognized and substituted by chaperones/remodelers as a distinct unit, can assemble independently and is stable during nucleosome unwinding. In this review we discuss how sequence and structural variations in H2A-H2B dimers may provide necessary complexity and confer the nucleosome functional variability.

  17. Simulated photodetachment spectra of AlH2-

    NASA Astrophysics Data System (ADS)

    Mok, Daniel K. W.; Lee, Edmond P. F.; Chau, Foo-tim; Dyke, John M.

    2013-07-01

    We have carried out high-level ab initio calculations on AlH2 and its anion, as well as Franck-Condon factor calculations, which include anharmonicity and Duschinsky rotation, to simulate the photodetachment spectrum of AlH2-, with the aim of assigning the very recently reported photodetachment spectrum of AlH2- [X. Zhang, H. Wang, E. Collins, A. Lim, G. Ganteför, B. Kiran, H. Schnöckel, B. Eichhorn, and K. Bowen, J. Chem. Phys. 138, 124303 (2013)], 10.1063/1.4796200. However, our simulated spectra do not support the assignment of the reported experimental spectrum to AlH2-.

  18. A shock tube study of OH + H(2)O(2) --> H(2)O + HO(2) and H(2)O(2) + M --> 2OH + M using laser absorption of H(2)O and OH.

    PubMed

    Hong, Zekai; Cook, Robert D; Davidson, David F; Hanson, Ronald K

    2010-05-13

    The rate constants of the reactions: (1) H2O2+M-->2OH+M, (2) OH+H2O2-->H2O+HO2 were measured in shock-heated H(2)O(2)/Ar mixtures using laser absorption diagnostics for H(2)O and OH. Time-histories of H(2)O were monitored using tunable diode laser absorption at 2550.96 nm, and time-histories of OH were achieved using ring dye laser absorption at 306 nm. Initial H(2)O(2) concentrations were also determined utilizing the H(2)O diagnostic. On the basis of simultaneous time-history measurements of OH and H(2)O, k(2) was found to be 4.6 x 10(13) exp(-2630 K/T) [cm(3) mol(-1) s(-1)] over the temperature range 1020-1460 K at 1.8 atm; additional measurements of k(2) near 1 atm showed no significant pressure dependence. Similarly, k(1) was found to be 9.5 x 10(15) exp(-21 250 K/T) [cm(3) mol(-1) s(-1)] over the same temperature and pressure range.

  19. H2S and Blood Vessels: An Overview.

    PubMed

    Yang, Guangdong; Wang, Rui

    2015-01-01

    The physiological and biomedical importance of hydrogen sulfide (H2S) has been fully recognized in the cardiovascular system as well as in the rest of the body. In blood vessels, cystathionine γ-lyase (CSE) is a major H2S-producing enzyme expressed in both smooth muscle and endothelium as well as periadventitial adipose tissues. Regulation of H2S production from CSE is controlled by a complex integration of transcriptional, posttranscriptional, and posttranslational mechanisms in blood vessels. In smooth muscle cells, H2S regulates cell apoptosis, phenotypic switch, relaxation and contraction, and calcification. In endothelial cells, H2S controls cell proliferation, cellular senescence, oxidative stress, inflammation, etc. H2S interacts with nitric oxide and acts as an endothelium-derived relaxing factor and an endothelium-derived hyperpolarizing factor. H2S generated from periadventitial adipose tissues acts as an adipocyte-derived relaxing factor and modulates the vascular tone. Extensive evidence has demonstrated the beneficial roles of the CSE/H2S system in various blood vessel diseases, such as hypertension, atherosclerosis, and aortic aneurysm. The important roles signaling in the cardiovascular system merit further intensive and extensive investigation. H2S-releasing agents and CSE activators will find their great applications in the prevention and treatment of blood vessel-related disorders.

  20. Legumes, N2 fixation and the H2 cycle

    NASA Astrophysics Data System (ADS)

    Layzell, D. B.

    2004-12-01

    Legume plants such as soybean or pea can form symbiotic, N2 fixing associations with bacteria that exist in root nodules. For every N2 fixed, 1 to 3 H2 are produced as a by-product of the nitrogenase reaction. Therefore, a typical N2 fixing legume crop produces about 200,000 L H2 gas (at STP) per hectare per crop season. This paper will summarize our current understanding of the processes leading to H2 production in legumes, the magnitude of H2 production associated with global cropping systems, and the implications for its production and oxidation on both the legumes and the soils in which they grow. Specific points may include: ˜ In symbioses lacking uptake hydrogenase (HUP) activity (thought to be the majority of crop legumes), the H2 diffuses into the soil where it is oxidized by soil microbes that grow up around the legume nodules. The kinetic properties of these microbes are very different (higher Km and Vmax) from that of microbes in soils exposed to normal air (ca. 0.5 ppm H2); ˜ Laboratory studies indicate that 60% of the reducing power from H2 is coupled to O2 uptake, whereas 40% is coupled to autotrophic CO2 fixation. The latter process should increase soil carbon stocks by about 25 kg C/ha/yr; ˜ At the site of the nitrogenase enzyme, H2 production is autocatalytic such that the higher the H2 concentration, the more H2 is produced and the less N2 fixed. The variable O2 diffusion barrier in legumes can act to restrict H2 diffusion from the nodule, thereby increasing the relative magnitude of H2 production versus N2 fixation; ˜ Studies to understand why legume symbioses make such an energy investment in H2 production have led to the discovery that H2 treated soils have improved fertility, supporting the growth and yield of legume and non-legume crops. This observation may account for the benefits of legumes when used in rotation with cereal crops, a phenomenon that has been used by farmers for over 2000 years, but which has remained unexplained. An

  1. Particulate filtration for sorbent-based H2 storage

    NASA Astrophysics Data System (ADS)

    van Hassel, Bart A.; Karra, Jagadeswara R.

    2016-01-01

    A method was developed for sizing the particulate filter that can be used inside a sorption-based onboard hydrogen storage system for light-duty vehicles. The method is based on a trade-off between the pressure drop across the particulate filter (during the fill of the H2 storage tank or during its discharge while driving) and the effect of this pressure drop on the usable amount of H2 gas from the H2 storage system. The permeability and filtration efficiency of the particulate filters (in the absence and presence of MOF-5 particulates) was quantified in this study, with an emphasis on meeting DOE's H2 purity requirements.

  2. H2S: a novel gasotransmitter that signals by sulfhydration

    PubMed Central

    Paul, Bindu D.; Snyder, Solomon H.

    2015-01-01

    Hydrogen sulfide is a member of the growing family of gasotransmitters. Once regarded as a noxious molecule predominantly present in the atmosphere, H2S is now known to be synthesized endogenously in mammals. H2S participates in a myriad of physiological processes ranging from regulation of blood pressure to neuroprotection. Its chemical nature precludes H2S from being stored in vesicles and acting on receptor proteins in the fashion of other chemical messengers. Thus, novel cellular mechanisms have evolved to mediate its effects. This article focuses on sulfhydration (or persulfidation), which appears to be the principal post-translational modification elicited by H2S. PMID:26439534

  3. Vibrationally excited H2 in the upper atmosphere of Saturn

    NASA Technical Reports Server (NTRS)

    Majeed, Tariq; Yelle, Roger V.; Mcconnell, John C.

    1990-01-01

    The impact of resonance fluorescense of solar EUV radiation by H2 on the distribution of the vibrational levels of H2 in the upper atmosphere of Saturn is considered. It appears that, for vibration levels, v not smaller than 3, this is the most important source, more important than those due to photoelectron induced fluorescence, recombination of molecular ions such as H3(+), and vibrational excitation of H2 by photoelectron impact. Based on the Voyager limb observations of H2 band emission, it is estimated that some of the higher vibrational levels may have effective temperatures about 3500 K. Such high vibrational densities may have an impact on ionospheric densities.

  4. Analysis of performance losses of direct ethanol fuel cells with the aid of a reference electrode

    NASA Astrophysics Data System (ADS)

    Li, Guangchun; Pickup, Peter G.

    The performances of direct ethanol fuel cells with different anode catalysts, different ethanol concentrations, and at different operating temperatures have been studied. The performance losses of the cell have been separated into individual electrode performance losses with the aid of a reference electrode, ethanol crossover has been quantified, and CO 2 and acetic acid production have been measured by titration. It has been shown that the cell performance strongly depends on the anode catalyst, ethanol concentration, and operating temperature. It was found that the cathode and anode exhibit different dependences on ethanol concentration and operating temperature. The performance of the cathode is very sensitive to the rate of ethanol crossover. Product analysis provides insights into the mechanisms of electro-oxidation of ethanol.

  5. Fermentation of sugars in orange peel hydrolysates to ethanol by recombinant Escherichia coli KO11

    SciTech Connect

    Grohmann, K.; Cameron, R.G.; Buslig, B.S.

    1995-12-31

    The conversion of monosaccharides in orange peel hydrolysates to ethanol by recombinant Escherichia coli KO11 has been investigated in pH-controlled batch fermentations at 32 and 37{degrees}C. pH values and concentration of peel hydrolysate were varied to determine approximate optimal conditions and limitations of these fermentations. Very high yields of ethanol were achieved by this microorganism at reasonable ethanol concentrations (28-48 g/L). The pH range between 5.8 and 6.2 appears to be optimal. The microorganism can convert all major monosaccharides in orange peel hydrolysates to ethanol and to smaller amounts of acetic and lactic acids. Acetic acid is coproduced in equimolar amounts with ethanol by catabolism of salts of galacturonic acid.

  6. Production of ethanol from corn stover hemicellulose hydrolyzate using Pichia stipitis.

    PubMed

    Agbogbo, Frank K; Wenger, Kevin S

    2007-11-01

    Hemicellulose liquid hydrolyzate from dilute acid pretreated corn stover was fermented to ethanol using Pichia stipitis CBS 6054. The fermentation rate increased with aeration but the pH also increased due to consumption of acetic acid by Pichia stipitis. Hemicellulose hydrolyzate containing 34 g/L xylose, 8 g/L glucose, 8 g/L Acetic acid, 0.73 g/L furfural, and 1 g/L hydroxymethyl furfural was fermented to 15 g/L ethanol in 72 h. The yield in all the hemicellulose hydrolyzates was 0.37-0.44 g ethanol/g (glucose + xylose). Nondetoxified hemicellulose hydrolyzate from dilute acid pretreated corn stover was fermented to ethanol with high yields, and this has the potential to improve the economics of the biomass to ethanol process.

  7. A Simple Way to Pattern Mn_12-acetate Thin Films

    NASA Astrophysics Data System (ADS)

    Kim, K.; Seo, D. M.; Means, J.; Viswanathan, M.; Teizer, W.

    2004-03-01

    We have observed that Mn_12-acetate ([Mn_12O_12(CH_3COO)_16(H_2O)_4]ot2CH_3COOHot4H_2O) molecules, dissolved in organic solvents, can be self-assembled along the edge of the Mn_12 solution droplet on a Si/SiO2 substrate as the solvent is evaporated. This phenomenon may be related to the well known "coffee-stain effect"”, which leads to a dense particulate deposit along the edge of a drying droplet of coffee on a solid surface. In our study, we have observed such a deposit of Mn_12-acetate at the perimeter of a droplet, after a dilute solution in various organic solvents has been dried. We investigated how the deposits depend on the evaporation rate. Also, we controlled the concentration of the solution to find its relation to the resulting pattern deposit. By patterning the surface with resist and performing a lift-off we created what are, to our knowledge, the first artificial patterns of Mn_12-acetate. This may allow for convenient thin film devices of Mn_12-acetate and work in this direction is ongoing. This work was supported by the Texas Higher Education Coordinating Board and Texas A University.

  8. Relative importance of H2 and H2S as energy sources for primary production in geothermal springs.

    PubMed

    D'Imperio, Seth; Lehr, Corinne R; Oduro, Harry; Druschel, Greg; Kühl, Michael; McDermott, Timothy R

    2008-09-01

    Geothermal waters contain numerous potential electron donors capable of supporting chemolithotrophy-based primary production. Thermodynamic predictions of energy yields for specific electron donor and acceptor pairs in such systems are available, although direct assessments of these predictions are rare. This study assessed the relative importance of dissolved H(2) and H(2)S as energy sources for the support of chemolithotrophic metabolism in an acidic geothermal spring in Yellowstone National Park. H(2)S and H(2) concentration gradients were observed in the outflow channel, and vertical H(2)S and O(2) gradients were evident within the microbial mat. H(2)S levels and microbial consumption rates were approximately three orders of magnitude greater than those of H(2). Hydrogenobaculum-like organisms dominated the bacterial component of the microbial community, and isolates representing three distinct 16S rRNA gene phylotypes (phylotype = 100% identity) were isolated and characterized. Within a phylotype, O(2) requirements varied, as did energy source utilization: some isolates could grow only with H(2)S, some only with H(2), while others could utilize either as an energy source. These metabolic phenotypes were consistent with in situ geochemical conditions measured using aqueous chemical analysis and in-field measurements made by using gas chromatography and microelectrodes. Pure-culture experiments with an isolate that could utilize H(2)S and H(2) and that represented the dominant phylotype (70% of the PCR clones) showed that H(2)S and H(2) were used simultaneously, without evidence of induction or catabolite repression, and at relative rate differences comparable to those measured in ex situ field assays. Under in situ-relevant concentrations, growth of this isolate with H(2)S was better than that with H(2). The major conclusions drawn from this study are that phylogeny may not necessarily be reliable for predicting physiology and that H(2)S can dominate over H(2

  9. Relative Importance of H2 and H2S as Energy Sources for Primary Production in Geothermal Springs▿ †

    PubMed Central

    D'Imperio, Seth; Lehr, Corinne R.; Oduro, Harry; Druschel, Greg; Kühl, Michael; McDermott, Timothy R.

    2008-01-01

    Geothermal waters contain numerous potential electron donors capable of supporting chemolithotrophy-based primary production. Thermodynamic predictions of energy yields for specific electron donor and acceptor pairs in such systems are available, although direct assessments of these predictions are rare. This study assessed the relative importance of dissolved H2 and H2S as energy sources for the support of chemolithotrophic metabolism in an acidic geothermal spring in Yellowstone National Park. H2S and H2 concentration gradients were observed in the outflow channel, and vertical H2S and O2 gradients were evident within the microbial mat. H2S levels and microbial consumption rates were approximately three orders of magnitude greater than those of H2. Hydrogenobaculum-like organisms dominated the bacterial component of the microbial community, and isolates representing three distinct 16S rRNA gene phylotypes (phylotype = 100% identity) were isolated and characterized. Within a phylotype, O2 requirements varied, as did energy source utilization: some isolates could grow only with H2S, some only with H2, while others could utilize either as an energy source. These metabolic phenotypes were consistent with in situ geochemical conditions measured using aqueous chemical analysis and in-field measurements made by using gas chromatography and microelectrodes. Pure-culture experiments with an isolate that could utilize H2S and H2 and that represented the dominant phylotype (70% of the PCR clones) showed that H2S and H2 were used simultaneously, without evidence of induction or catabolite repression, and at relative rate differences comparable to those measured in ex situ field assays. Under in situ-relevant concentrations, growth of this isolate with H2S was better than that with H2. The major conclusions drawn from this study are that phylogeny may not necessarily be reliable for predicting physiology and that H2S can dominate over H2 as an energy source in terms of

  10. Equations of state for H2, H2O, and H2-H2O fluid mixtures at temperatures above 0.01° C and at high pressures

    NASA Astrophysics Data System (ADS)

    Rimbach, Helmut; Chatterjee, Niranjan D.

    1987-11-01

    Modified Redlich-Kwong (MRK) equations of state have been derived for the pure fluid species H2 and H2O by expressing the parameter a as a function of T and P, and b as as a function of P only. These equations are valid above 0° and 0.01° C, respectively. For H2O, the prediction of volumes is successful not only in the supercritical, but also in the subcritical range. As a result of this, the saturation curve of H2O can be calculated with a maximum deviation of ±1.4 bar in the range 100 350° C. Between 350° C and the critical point (374.15° C), the uncertainty increases somewhat; this is due to a fundamental inadequacy of the Redlich-Kwong equation itself. These equations of state permit extrapolations to pressures of 100 kbar for H2 and at least 200 kbar for H2O and are, therefore, eminently suited for geochemical applications. Formulation of the MRK of the binary H2-H2O mixtures was achieved by assuming the quadratic mixing rule for the parameters a mix and b+mix. To derive the cross coefficients, aH2-H2Oand b H 2-H 2O, adjustable corrective factors ɛ and τ had to be introduced. The T- and P-dependences of ɛ and τ are based on P-V-T-X H 2 data (Seward and Franck 1981) to 440° C and 2500 bar. The resulting equation of state very satisfactorily reproduces the volumes observed experimentally at various sets of T, P, and X H 2. At a total pressure of 2 kbar, positive deviation from ideal mixing behaviour is still perceptible at as high a temperature as 1000° C. At some temperature around 380° C, phase separation sets in, an aqueous solution with dissolved H2 coexisting in equilibrium with an H2-rich fluid with dissolved H2O. The computed P-T-X H 2 surface of this two-phase region agrees well with that observed in Seward and Franck's (1981) experiments. An independent proof of the validity of this equation of state is the accuracy with which H {m/ex}can be predicted. Calorimetric measurements of H {m/ex}(Smith et al. 1983, Wormald and Colling 1985

  11. Highly sensitive hydrogen sulfide (H2 S) gas sensors from viral-templated nanocrystalline gold nanowires

    NASA Astrophysics Data System (ADS)

    Moon, Chung Hee; Zhang, Miluo; Myung, Nosang V.; Haberer, Elaine D.

    2014-04-01

    A facile, site-specific viral-templated assembly method was used to fabricate sensitive hydrogen sulfide (H2S) gas sensors at room temperature. A gold-binding M13 bacteriophage served to organize gold nanoparticles into linear arrays which were used as seeds for subsequent nanowire formation through electroless deposition. Nanowire widths and densities within the sensors were modified by electroless deposition time and phage concentration, respectively, to tune device resistance. Chemiresistive H2S gas sensors with superior room temperature sensing performance were produced with sensitivity of 654%/ppmv, theoretical lowest detection limit of 2 ppbv, and 70% recovery within 9 min for 0.025 ppmv. The role of the viral template and associated gold-binding peptide was elucidated by removing organics using a short O2 plasma treatment followed by an ethanol dip. The template and gold-binding peptide were crucial to electrical and sensor performance. Without surface organics, the resistance fell by several orders of magnitude, the sensitivity dropped by more than a factor of 100 to 6%/ppmv, the lower limit of detection increased, and no recovery was detected with dry air flow. Viral templates provide a novel, alternative fabrication route for highly sensitive, nanostructured H2S gas sensors.

  12. Tuning the conductance of H2O@C60 by position of the encapsulated H2O

    PubMed Central

    Zhu, Chengbo; Wang, Xiaolin

    2015-01-01

    The change of conductance of single-molecule junction in response to various external stimuli is the fundamental mechanism for the single-molecule electronic devices with multiple functionalities. We propose the concept that the conductance of molecular systems can be tuned from inside. The conductance is varied in C60 with encapsulated H2O, H2O@C60. The transport properties of the H2O@C60-based nanostructure sandwiched between electrodes are studied using first-principles calculations combined with the non-equilibrium Green’s function formalism. Our results show that the conductance of the H2O@C60 is sensitive to the position of the H2O and its dipole direction inside the cage with changes in conductance up to 20%. Our study paves a way for the H2O@C60 molecule to be a new platform for novel molecule-based electronics and sensors. PMID:26643873

  13. Physiology of the fuel ethanol strain Saccharomyces cerevisiae PE-2 at low pH indicates a context-dependent performance relevant for industrial applications.

    PubMed

    Della-Bianca, Bianca E; de Hulster, Erik; Pronk, Jack T; van Maris, Antonius J A; Gombert, Andreas K

    2014-12-01

    Selected Saccharomyces cerevisiae strains are used in Brazil to produce the hitherto most energetically efficient first-generation fuel ethanol. Although genome and some transcriptome data are available for some of these strains, quantitative physiological data are lacking. This study investigates the physiology of S. cerevisiae strain PE-2, widely used in the Brazilian fuel ethanol industry, in comparison with CEN.PK113-7D, a reference laboratory strain, focusing on tolerance to low pH and acetic acid stress. Both strains were grown in anaerobic bioreactors, operated as batch, chemostat or dynamic continuous cultures. Despite their different backgrounds, biomass and product formation by the two strains were similar under a range of conditions (pH 5 or pH < 3, with or without 105 mM acetic acid added). PE-2 displayed a remarkably higher fitness than CEN.PK113-7D during batch cultivation on complex Yeast extract - Peptone - Dextrose medium at low pH (2.7). Kinetics of viability loss of non-growing cells, incubated at pH 1.5, indicated a superior survival of glucose-depleted PE-2 cells, when compared with either CEN.PK113-7D or a commercial bakers' strain. These results indicate that the sulfuric acid washing step, used in the fuel ethanol industry to decrease bacterial contamination due to non-aseptic operation, might have exerted an important selective pressure on the microbial populations present in such environments.

  14. Disproportionation Kinetics of Hypoiodous Acid As Catalyzed and Suppressed by Acetic Acid-Acetate Buffer.

    PubMed

    Urbansky, Edward T.; Cooper, Brian T.; Margerum, Dale W.

    1997-03-26

    The kinetics of the disproportionation of hypoiodous acid to give iodine and iodate ion (5HOI right harpoon over left harpoon 2I(2) + IO(3)(-) + H(+) + 2H(2)O) are investigated in aqueous acetic acid-sodium acetate buffer. The rate of iodine formation is followed photometrically at -log [H(+)] = 3.50, 4.00, 4.50, and 5.00, &mgr; = 0.50 M (NaClO(4)), and 25.0 degrees C. Both catalytic and inhibitory buffer effects are observed. The first process is proposed to be a disproportionation of iodine(I) to give HOIO and I(-); the iodide then reacts with HOI to give I(2). The reactive species (acetato-O)iodine(I), CH(3)CO(2)I, is postulated to increase the rate by assisting in the formation of I(2)O, a steady-state species that hydrolyzes to give HOIO and I(2). Inhibition is postulated to result from the formation of the stable ion bis(acetato-O)iodate(I), (CH(3)CO(2))(2)I(-), as buffer concentration is increased. This species is observed spectrophotometrically with a UV absorption shoulder (lambda = 266 nm; epsilon = 530 M(-)(1) cm(-)(1)). The second process is proposed to be a disproportionation of HOIO to give IO(3)(-) and I(2). Above 1 M total buffer, the reaction becomes reversible with less than 90% I(2) formation. Rate and equilibrium constants are resolved and reported for the proposed mechanism.

  15. The singlet-triplet splittings in AsH + 2, SbH + 2, and BiH + 2 and bond energies and ionization potentials of AsH2

    NASA Astrophysics Data System (ADS)

    Balasubramanian, K.

    1989-08-01

    The three low-lying electronic states (1A1, 3B1, 1B1) and their five spin-orbit states of AsH+2, SbH+2, and BiH+2 are investigated using complete active space MCSCF/second-order configuration interaction/relativistic CI schemes (CASSCF/SOCI/RCI). In addition the X 2B1 ground state and the excited 2A1 state of AsH2 and the X 3Σ- state of AsH are studied at the same levels of theory. The CASSCF/SOCI calculations yield De (HAs-H)=69.1 kcal/mol and De (AsH)=62.4 kcal/mol in excellent agreement with experimental values of D0(HAs-H)=66.5 kcal/mol and D0(As-H)=64.6 kcal/mol obtained by Berkowitz recently. The adiabatic CASSCF/SOCI ionization potential of the X 2B1 state of AsH2 to form the X 1A1 state of AsH+2 is 9.25 eV in comparison to an experimental value of 9.44 eV obtained by Berkowitz and Cho. The X 1A1-3B1 separations of AsH+2, SbH+2, and BiH+2 are calculated as 22, 31, and 35 kcal/mol, respectively. All the three ions were found to have bent equilibrium structures. The spin-orbit effects are found to be very significant for both BiH+2 and SbH+2, which changed the bond angle of 3B1(A1) to a considerable extent by contamination with 1A1. The relativistic density matrices and dipole moments are also obtained for all the species from the RCI wave functions.

  16. Effect of H2O, and combined effects of H2O + F, H2O + CO2, and H2O + F + CO2 on the viscosity of a natural basalt from Fuego volcano, Guatemala

    NASA Astrophysics Data System (ADS)

    Robert, G.; Whittington, A. G.; Knipping, J.; Scherbarth, S.; Stechern, A.; Behrens, H.

    2012-12-01

    We measured the viscosity of 5 series of remelted natural basalt from Fuego volcano, Guatemala. These series include single and multiple volatile species: H2O, F, H2O-F, H2O-CO2, and H2O-CO2-F. The hydrous glasses were synthesized at 3 kbar and 1250°C in Internally Heated Pressure Vessels. The multiple volatile series were synthesized at 5 kbar and 1250°C. CO2 was added as Ag2C2O4, F as AlF3, and H2O as distilled water. The anhydrous, F-bearing series was synthesized at 1 atm by simply remelting the Fuego basalt and adding F as CaF2.The natural, dry, remelted Fuego basalt has an NBO/T of 0.64. The following comparisons are based on parallel-plate viscosity measurements in the range ~108 to 1012 Pa s. The temperature at which the viscosity is 1012 Pa s (T12) is taken to be the viscosimetric glass transition temperature (Tg). The addition of 2 wt.% H2O results in a decrease of T12 of ~150°C for basalt. Fluorine on its own has a measurable, but much smaller effect, than the equivalent amount of water. Indeed, ~2 wt.% F results in a T12 depression of only ~30°C. When H2O and F are both present, their effects are approximately additive. For example, the viscosity of a basalt with 1.44 wt.% H2O is very similar to the viscosity of a basalt with ~1 wt.% H2O and ~1.25 wt.% F, and the viscosities of a basalt with 2.29 wt.% H2O and a basalt with ~1.65 wt.% H2O and ~1.3 wt.% F are also very similar. The effect of CO2 is somewhat ambiguous. The viscosity of a basalt with ~1.7 wt.% H2O, ~1.3 wt.% F and ~0.2 wt.% CO2 is essentially the same as the viscosity of a basalt with 2.29 wt.% H2O, so CO2 seems to have a negligible or even viscosity-increasing effect when F and H2O are also present. However, a basalt with ~0.84 wt.% H2O and ~0.09 wt.% CO2 has about the same viscosity as a basalt with 1.34 wt.% H2O, which could suggest a strong (viscosity-decreasing) effect of very small amounts of CO2. These results suggest that the effects on viscosity of F in basaltic systems are

  17. Pressure-induced superconductivity in H2-containing hydride PbH4(H2)2

    PubMed Central

    Cheng, Ya; Zhang, Chao; Wang, Tingting; Zhong, Guohua; Yang, Chunlei; Chen, Xiao-Jia; Lin, Hai-Qing

    2015-01-01

    High pressure structure, stability, metallization, and superconductivity of PbH4(H2)2, a H2-containing compound combining one of the heaviest elements with the lightest element, are investigated by the first-principles calculations. The metallic character is found over the whole studied pressure range, although PbH4(H2)2 is metastable and easily decompose at low pressure. The decomposition pressure point of 133 GPa is predicted above which PbH4(H2)2 is stable both thermodynamically and dynamically with the C2/m symmetry. Interestedly, all hydrogen atoms pairwise couple into H2 quasi-molecules and remain this style up to 400 GPa in the C2/m structure. At high-pressure, PbH4(H2)2 tends to form the Pb-H2 alloy. The superconductivity of Tc firstly rising and then falling is observed in the C2/m PbH4(H2)2. The maximum of Tc is about 107 K at 230 GPa. The softening of intermediate-frequency phonon induced by more inserted H2 molecules is the main origin of the high Tc. The results obtained represent a significant step toward the understanding of the high pressure behavior of metallic hydrogen and hydrogen-rich materials, which is helpful for obtaining the higher Tc. PMID:26559369

  18. Pressure-induced superconductivity in H2-containing hydride PbH4(H2)2

    NASA Astrophysics Data System (ADS)

    Cheng, Ya; Zhang, Chao; Wang, Tingting; Zhong, Guohua; Yang, Chunlei; Chen, Xiao-Jia; Lin, Hai-Qing

    2015-11-01

    High pressure structure, stability, metallization, and superconductivity of PbH4(H2)2, a H2-containing compound combining one of the heaviest elements with the lightest element, are investigated by the first-principles calculations. The metallic character is found over the whole studied pressure range, although PbH4(H2)2 is metastable and easily decompose at low pressure. The decomposition pressure point of 133 GPa is predicted above which PbH4(H2)2 is stable both thermodynamically and dynamically with the C2/m symmetry. Interestedly, all hydrogen atoms pairwise couple into H2 quasi-molecules and remain this style up to 400 GPa in the C2/m structure. At high-pressure, PbH4(H2)2 tends to form the Pb-H2 alloy. The superconductivity of Tc firstly rising and then falling is observed in the C2/m PbH4(H2)2. The maximum of Tc is about 107 K at 230 GPa. The softening of intermediate-frequency phonon induced by more inserted H2 molecules is the main origin of the high Tc. The results obtained represent a significant step toward the understanding of the high pressure behavior of metallic hydrogen and hydrogen-rich materials, which is helpful for obtaining the higher Tc.

  19. Fluoroantimonic acid hexahydrate (HSbF6-6H2O) catalysis: The ring-opening polymerization of epoxidized soybean oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ring-opening polymerization of epoxidized soybean oil (ESO) catalyzed by a super acid, fluroantimonic acid hexahydrate (HSbF6-6H2O), in ethyl acetate was conducted in an effort to develop useful biodegradable polymers. The resulting polymerized ESO (SA-RPESO) were characterized by using infrared (IR...

  20. Ring-opening polymerization of epoxidized soybean oil catalyzed by the superacid, Fluroantimonic acid hexahydrate (HSbF6-6H2O)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ring-opening polymerization of epoxidized soybean oil (ESO) catalyzed by the super acid, fluroantimonic acid hexahydrate (HSbF6-6H2O), in ethyl acetate was conducted. The resulting polymers, SA-RPESO, were characterized using infrared spectroscopy, differential scanning calorimetry, thermogravimetri...

  1. Alcohol causes a fatty pancreas. A rat model of ethanol-induced pancreatic steatosis.

    PubMed

    Wilson, J S; Colley, P W; Sosula, L; Pirola, R C; Chapman, B A; Somer, J B

    1982-01-01

    To develop an animal mode of alcoholic pancreatic steatosis, female Wistar rats were pair fed liquid diets, containing ethanol as 36% of calories or an isocaloric amount of carbohydrate for 3 weeks. Electron microscopic examination showed lipid vesicles localized principally at the bases of pancreatic acinar cells in the ethanol-fed rats. Ethanol feeding significantly increased pancreatic content of cholesteryl ester without changing levels of other lipids. Ethanol feeding enhanced labeled acetate, palmitate, oleate, and linoleate incorporation into cholesteryl ester. Therefore, increased esterification of cholesterol may, in part, explain the observed accumulation of cholesteryl ester.

  2. H2 cycling and microbial bioenergetics in anoxic sediments

    NASA Technical Reports Server (NTRS)

    Hoehler, Tori M.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    The simple biochemistry of H2 is central to a large number of microbial processes, affecting the interaction of organisms with each other and with the environment. In anoxic sediments, the great majority of microbial redox processes involve H2 as a reactant, product, or potential by-product, and the thermodynamics of these processes are thus highly sensitive to fluctuations in environmental H2 concentrations. In turn, H2 concentrations are controlled by the activity of H2-consuming microorganisms, which efficiently utilize this substrate down to levels which correspond to their bioenergetic limitations. Consequently, any environmental change which impacts the thermodynamics of H2-consuming organisms is mirrored by a corresponding change in H2 concentrations. This phenomenon is illustrated in anoxic sediments from Cape Lookout Bight, NC, USA: H2 concentrations are controlled by a suite of environmental parameters (e.g., temperature, sulfate concentrations) in a fashion which can be quantitatively described by a simple thermodynamic model. These findings allow us to calculate the apparent minimum quantity of biologically useful energy in situ. We find that sulfate reducing bacteria are not active at energy yields below -18 kJ per mole sulfate, while methanogenic archaea exhibit a minimum close to -10 kJ per mole methane.

  3. H2S, a novel gasotransmitter, involves in gastric accommodation.

    PubMed

    Xiao, Ailin; Wang, Hongjuan; Lu, Xin; Zhu, Jianchun; Huang, Di; Xu, Tonghui; Guo, Jianqiang; Liu, Chuanyong; Li, Jingxin

    2015-11-04

    H2S is produced mainly by two enzymes:cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE), using L-cysteine (L-Cys) as the substrate. In this study, we investigated the role of H2S in gastric accommodation using CBS(+/-) mice, immunohistochemistry, immunoblot, methylene blue assay, intragastric pressure (IGP) recording and electrical field stimulation (EFS). Mouse gastric fundus expressed H2S-generating enzymes (CBS and CSE) and generated detectable amounts of H2S. The H2S donor, NaHS or L-Cys, caused a relaxation in either gastric fundus or body. The gastric compliance was significantly increased in the presence of L-Cys (1 mM). On the contrary, AOAA, an inhibitor for CBS, largely inhibited gastric compliance. Consistently, CBS(+/-) mice shows a lower gastric compliance. However, PAG, a CSE inhibitor, had no effect on gastric compliances. L-Cys enhances the non-adrenergic, non-cholinergic (NANC) relaxation of fundus strips, but AOAA reduces the magnitude of relaxations to EFS. Notably, the expression level of CBS but not CSE protein was elevated after feeding. Consistently, the production of H2S was also increased after feeding in mice gastric fundus. In addition, AOAA largely reduced food intake and body weight in mice. Furthermore, a metabolic aberration of H2S was found in patients with functional dyspepsia (FD). In conclusion, endogenous H2S, a novel gasotransmitter, involves in gastric accommodation.

  4. Role of H2S Donors in Cancer Biology.

    PubMed

    Lee, Zheng-Wei; Deng, Lih-Wen

    2015-01-01

    Hydrogen sulfide (H2S) donors including organosulfur compounds (OSC), inorganic sulfide salts, and synthetic compounds are useful tools in studies to elucidate the effects of H2S in cancer biology. Studies using such donors have shown the ability of H2S to suppress tumor growth both in vitro and in vivo, with some of them suggesting the selectivity of its cytotoxic effects to cancer cells. In addition to promoting cancer cell death, H2S donors were also found to inhibit cancer angiogenesis and metastasis. The underlying mechanisms for the anticancer activities of H2S involve (1) cell signaling pathways, such as MAPK and STAT; (2) cell cycle regulation; (3) microRNAs regulation; and (4) cancer metabolism and pH regulation. Altogether, compiling evidences have demonstrated the great potential of using H2S donors as anticancer agents. Nevertheless, the application and development of H2S for therapy are still facing challenges as identification of molecular targets of H2S awaits further investigation.

  5. Crystal growth simulations of H(2)S hydrate.

    PubMed

    Liang, Shuai; Kusalik, Peter G

    2010-07-29

    In this paper, we report a molecular simulation study exploring the crystal growth behavior of H(2)S hydrates within two-phase (H(2)S hydrate crystal and H(2)S aqueous solution) and three-phase (H(2)S hydrate crystal, liquid H(2)S, and H(2)S aqueous solution) systems. The microscopic mechanisms of growth, as well as the interfacial properties during the heterogeneous crystal growth process, are probed. We find that the H(2)S hydrate can be grown at a higher rate than methane hydrates under comparable conditions (Vatamanu, J.; Kusalik, P. G. J. Phys. Chem. B 2006, 110, 15896). The three-phase simulations, which also allow us to identify the simulation conditions on the experimental phase diagram, demonstrate that the present models reasonably reproduce the phase behavior of this system. We find that the crystal interface has a strong affinity for water molecules. We observed a relatively low level of defects in the newly formed H(2)S hydrate crystal.

  6. Endogenous mitigation of H2S inside of the landfills.

    PubMed

    Fang, Yuan; Zhong, Zhong; Shen, Dongsheng; Du, Yao; Xu, Jing; Long, Yuyang

    2016-02-01

    Vast quantities of hydrogen sulfide (H2S) emitted from landfill sites require urgent disposal. The current study focused on source control and examined the migration and conversion behavior of sulfur compounds in two lab-scale simulated landfills with different operation modes. It aimed to explore the possible strategies and mechanisms for H2S endogenous mitigation inside of landfills during decomposition. It was found that the strength of H2S emissions from the landfill sites was dependent on the municipal solid waste (MSW) degradation speed and vertical distribution of sulfide. Leachate recirculation can shorten both the H2S influence period and pollution risk to the surrounding environment. H2S endogenous mitigation may be achieved by chemical oxidation, biological oxidation, adsorption, and/or precipitation in different stages. Migration and conversion mainly affected H2S release behavior during the initial stabilization phase in the landfill. Microbial activities related to sulfur, nitrogen, and iron can further promote H2S endogenous mitigation during the high reducing phase. Thus, H2S endogenous mitigation can be effectively enhanced via control of the aforementioned processes.

  7. Improved Acetic Acid Resistance in Saccharomyces cerevisiae by Overexpression of the WHI2 Gene Identified through Inverse Metabolic Engineering.

    PubMed

    Chen, Yingying; Stabryla, Lisa; Wei, Na

    2016-01-29

    Development of acetic acid-resistant Saccharomyces cerevisiae is important for economically viable production of biofuels from lignocellulosic biomass, but the goal remains a critical challenge due to limited information on effective genetic perturbation targets for improving acetic acid resistance in the yeast. This study employed a genomic-library-based inverse metabolic engineering approach to successfully identify a novel gene target, WHI2 (encoding a cytoplasmatic globular scaffold protein), which elicited improved acetic acid resistance in S. cerevisiae. Overexpression of WHI2 significantly improved glucose and/or xylose fermentation under acetic acid stress in engineered yeast. The WHI2-overexpressing strain had 5-times-higher specific ethanol productivity than the control in glucose fermentation with acetic acid. Analysis of the expression of WHI2 gene products (including protein and transcript) determined that acetic acid induced endogenous expression of Whi2 in S. cerevisiae. Meanwhile, the whi2Δ mutant strain had substantially higher susceptibility to acetic acid than the wild type, suggesting the important role of Whi2 in the acetic acid response in S. cerevisiae. Additionally, overexpression of WHI2 and of a cognate phosphatase gene, PSR1, had a synergistic effect in improving acetic acid resistance, suggesting that Whi2 might function in combination with Psr1 to elicit the acetic acid resistance mechanism. These results improve our understanding of the yeast response to acetic acid stress and provide a new strategy to breed acetic acid-resistant yeast strains for renewable biofuel production.

  8. Improved Acetic Acid Resistance in Saccharomyces cerevisiae by Overexpression of the WHI2 Gene Identified through Inverse Metabolic Engineering

    PubMed Central

    Chen, Yingying; Stabryla, Lisa

    2016-01-01

    Development of acetic acid-resistant Saccharomyces cerevisiae is important for economically viable production of biofuels from lignocellulosic biomass, but the goal remains a critical challenge due to limited information on effective genetic perturbation targets for improving acetic acid resistance in the yeast. This study employed a genomic-library-based inverse metabolic engineering approach to successfully identify a novel gene target, WHI2 (encoding a cytoplasmatic globular scaffold protein), which elicited improved acetic acid resistance in S. cerevisiae. Overexpression of WHI2 significantly improved glucose and/or xylose fermentation under acetic acid stress in engineered yeast. The WHI2-overexpressing strain had 5-times-higher specific ethanol productivity than the control in glucose fermentation with acetic acid. Analysis of the expression of WHI2 gene products (including protein and transcript) determined that acetic acid induced endogenous expression of Whi2 in S. cerevisiae. Meanwhile, the whi2Δ mutant strain had substantially higher susceptibility to acetic acid than the wild type, suggesting the important role of Whi2 in the acetic acid response in S. cerevisiae. Additionally, overexpression of WHI2 and of a cognate phosphatase gene, PSR1, had a synergistic effect in improving acetic acid resistance, suggesting that Whi2 might function in combination with Psr1 to elicit the acetic acid resistance mechanism. These results improve our understanding of the yeast response to acetic acid stress and provide a new strategy to breed acetic acid-resistant yeast strains for renewable biofuel production. PMID:26826231

  9. Scavenging of H2O2 by mouse brain mitochondria

    PubMed Central

    Starkov, Anatoly A.; Andreyev, Alexander Yu; Zhang, Steven F.; Starkova, Natalia N.; Korneeva, Maria; Syromyatnikov, Mikhail; Popov, Vasily N.

    2015-01-01

    Mitochondrial reactive oxygen species (ROS) metabolism is unique in that mitochondria both generate and scavenge ROS. Recent estimates of ROS scavenging capacity of brain mitochondria are surprisingly high, ca. 9-12 nmol H2O2/min/mg, which is ~100 times higher than the rate of ROS generation. This raises a question whether brain mitochondria are a source or a sink of ROS. We studied the interaction between ROS generation and scavenging in mouse brain mitochondria by measuring the rate of removal of H2O2 added at a concentration of 0.4 μM, which is close to the reported physiological H2O2 concentrations in tissues, under conditions of low and high levels of mitochondrial H2O2 generation. With NAD-linked substrates, the rate of H2O2 generation by mitochondria was ~50–70 pmol/min/mg. The H2O2 scavenging dynamics was best approximated by the first order reaction equation. H2O2 scavenging was not affected by the uncoupling of mitochondria, phosphorylation of added ADP, or the genetic ablation of glutathione peroxidase 1, but decreased in the absence of respiratory substrates, in the presence of thioredoxin reductase inhibitor auranofin, or in partially disrupted mitochondria. With succinate, the rate of H2O2 generation was ~2,200–2,900 pmol/min/mg; the scavenging of added H2O2 was masked by a significant accumulation of generated H2O2 in the assay medium. The obtained data were fitted into a simple model that reasonably well described the interaction between H2O2 scavenging and production. It showed that mitochondria are neither a sink nor a source of H2O2, but can function as both at the same time, efficiently stabilizing exogenous H2O2 concentration at a level directly proportional to the ratio of the H2O2 generation rate to the rate constant of the first order scavenging reaction. PMID:25248416

  10. Measurements of H2O2 during WATOX-86

    NASA Astrophysics Data System (ADS)

    Heikes, Brian G.; Walega, James G.; Kok, Gregory L.; Lind, John A.; Lazrus, Allan L.

    1988-03-01

    Measurements of gas phase H2O2 were made on all Western Atlantic Ocean Experiment 1986 (WATOX-86) flights aboard the National Oceanic and Atmospheric Administration (NOAA) WP-3D aircraft. These were some of the first airborne real-time H2O2 measurements made in winter. Operation of the instru- ment was limited to altitude < 3.1 km with a detection limit, determined by interference considerations, of 0.05 parts per billion by volume (ppbv), 10% calibration accuracy and 0.03-ppbv precision. Experimental measurements showed the mean H2O2 to be 0.12 ppbv (standard deviation = 0.07, maximum = 1.2 ppbv). Vertical structure was observed with maximum H2O2 above the cloud-capped marine boundary layer. Boundary layer H2O2 was typically at or below the detection limit.

  11. Long-term variation of Saturn H2 emission

    NASA Technical Reports Server (NTRS)

    DeLand, Matthew T.; McGrath, Melissa

    1995-01-01

    The goal of this research effort was to analyze the long-term IUE database of Saturn images for the possible presence of diffuse H2 emissions, using techniques originally developed for analysis of Jupiter images. The poor S/N ratio in many of the Saturn images proved to be a significant limitation to the possible detection of H2 emission. The creation of a satisfactory background atmosphere model was also limited by difficulties in reproducing the observed C2H2 band structure at long wavelengths. The results currently available suggest that diffuse H2 emission is present on Saturn on some occasions. However, the IUE data are not able to indicate whether H2 emission is present at all times with a magnitude proportional to solar activity, as was shown for Jupiter.

  12. Infrared spectroscopy of V2+(H2O) complexes

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, B.; Duncan, M. A.

    2012-03-01

    Doubly charged vanadium-water complexes are produced by laser vaporization in a pulsed supersonic expansion. Size-selected ions are studied with infrared photodissociation spectroscopy in the O-H stretch region using argon complex predissociation. Density functional theory calculations provide structures and vibrational spectra of these ions. The O-H stretches of V2+(H2O) appear at lower frequencies than those of the free water molecule or V+(H2O). The symmetric stretch is more intense than the asymmetric stretch in both V+(H2O) and V2+(H2O) complexes. Spectra of V2+(H2O)Arn (n = 2-7) show that the coordination of the V2+ is filled with six ligands, i.e. one water and five argon atoms.

  13. Allogeneic H-2 antigen expression is insufficient for tumor rejection.

    PubMed Central

    Cole, G A; Cole, G A; Clements, V K; Garcia, E P; Ostrand-Rosenberg, S

    1987-01-01

    Murine A strain (KkDdLd) sarcoma I (SaI) tumor cells have been transfected with a cloned H-2Kb gene. The resulting clones (SKB clones) stably express high levels of a molecule that is serologically and biochemically indistinguishable from the H-2Kb antigen. SKB clones are not susceptible to cytotoxic T lymphocyte-mediated lysis by H-2Kb-specific bulk, cloned, or H-2Kb-restricted lymphocytic choriomeningitis virus-specific effectors. Survival times of A/J and B10.A mice challenged i.p. with the H-2Kb-expressing transfectants and the parental SaI cells are similar, suggesting that the presence of an allogeneic major histocompatibility complex class I antigen on the surface of this tumor line is insufficient for tumor rejection. Images PMID:3500477

  14. Aqueous-phase hydrogenation of acetic acid over transition metal catalysts

    SciTech Connect

    Olcay, Hakan; Xu, Lijun; Xu, Ye; Huber, George

    2010-01-01

    Catalytic hydrogenation of acetic acid to ethanol has been carried out in aqueous phase on several metals, with ruthenium being the most active and selective. DFT calculations suggest that the initial CO bond scission yielding acetyl is the key step and that the intrinsic reactivity of the metals accounts for the observed activity.

  15. Molecular hydrogen (H2) emissions from gasoline and diesel vehicles.

    PubMed

    Bond, S W; Alvarez, R; Vollmer, M K; Steinbacher, M; Weilenmann, M; Reimann, S

    2010-08-01

    This study assesses individual-vehicle molecular hydrogen (H2) emissions in exhaust gas from current gasoline and diesel vehicles measured on a chassis dynamometer. Absolute H2 emissions were found to be highest for motorcycles and scooters (141+/-38.6 mg km(-1)), approximately 5 times higher than for gasoline-powered automobiles (26.5+/-12.1 mg km(-1)). All diesel-powered vehicles emitted marginal amounts of H2 ( approximately 0.1 mg km(-1)). For automobiles, the highest emission factors were observed for sub-cycles subject to a cold-start (mean of 53.1+/-17.0 mg km(-1)). High speeds also caused elevated H2 emission factors for sub-cycles reaching at least 150 km h(-1) (mean of 40.4+/-7.1 mg km(-1)). We show that H2/CO ratios (mol mol(-1)) from gasoline-powered vehicles are variable (sub-cycle means of 0.44-5.69) and are typically higher (mean for automobiles 1.02, for 2-wheelers 0.59) than previous atmospheric ratios characteristic of traffic-influenced measurements. The lowest mean individual sub-cycle ratios, which correspond to high absolute emissions of both H2 and CO, were observed during cold starts (for automobiles 0.48, for 2-wheelers 0.44) and at high vehicle speeds (for automobiles 0.73, for 2-wheelers 0.45). This finding illustrates the importance of these conditions to observed H2/CO ratios in ambient air. Overall, 2-wheelers displayed lower H2/CO ratios (0.48-0.69) than those from gasoline-powered automobiles (0.75-3.18). This observation, along with the lower H2/CO ratios observed through studies without catalytic converters, suggests that less developed (e.g. 2-wheelers) and older vehicle technologies are largely responsible for the atmospheric H2/CO ratios reported in past literature.

  16. H2S concentrations in the heart after acute H2S administration: methodological and physiological considerations.

    PubMed

    Sonobe, Takashi; Haouzi, Philippe

    2016-12-01

    In this study, we have tried to characterize the limits of the approach typically used to determine H2S concentrations in the heart based on the amount of H2S evaporating from heart homogenates-spontaneously, after reaction with a strong reducing agent, or in a very acidic solution. Heart homogenates were prepared from male rats in control conditions or after H2S infusion induced a transient cardiogenic shock (CS) or cardiac asystole (CA). Using a method of determination of gaseous H2S with a detection limit of 0.2 nmol, we found that the process of homogenization could lead to a total disappearance of free H2S unless performed in alkaline conditions. Yet, after restoration of neutral pH, free H2S concentration from samples processed in alkaline and nonalkaline milieus were similar and averaged ∼0.2-0.4 nmol/g in both control and CS homogenate hearts and up to 100 nmol/g in the CA group. No additional H2S was released from control, CS, or CA hearts by using the reducing agent tris(2-carboxyethyl)phosphine or a strong acidic solution (pH < 2) to "free" H2S from combined pools. Of note, the reducing agent DTT produced a significant sulfide artifact and was not used. These data suggest that 1) free H2S found in heart homogenates is not a reflection of H2S present in a "living" heart and 2) the pool of combined sulfides, released in a strong reducing or acidic milieu, does not increase in the heart in a measurable manner even after toxic exposure to sulfide.

  17. Biological production of ethanol from coal

    SciTech Connect

    Not Available

    1990-01-01

    A batch kinetic study involving Clostridium lungdahlii in a mineral medium was carried out in order to provide baseline data for the effects of nutrients on product ratio and kinetics. The use of this minimal medium containing vitamins, minerals, select amino acids and salts showed both a lower maximum specific growth rate and a lower maximum specific uptake rate than found when using a complex medium supplemented with 0.01% yeast extract. At the same time, the product ratio was improved slightly in favor of ethanol over acetate. Future experiments will measure the effects of ammonia and phosphate limitation on product ratio and process kinetics.

  18. Self-Supported 3D PdCu Alloy Nanosheets as a Bifunctional Catalyst for Electrochemical Reforming of Ethanol.

    PubMed

    Zhao, Xiaojing; Dai, Lei; Qin, Qing; Pei, Fei; Hu, Chengyi; Zheng, Nanfeng

    2017-03-01

    3D PdCu alloy nanosheets exhibit enhanced electrocatalytic activity toward hydrogen evolution reaction and ethanol oxidation reaction in alkaline media. Simultaneous hydrogen and acetate production via a solar-powered cell for ethanol reforming has been fabricated using the nanosheets as bifunctional electrocatalysts. The device is promising for the production of both hydrogen and value-added chemicals using renewable energy.

  19. H2 distribution during the formation of multiphase molecular clouds

    NASA Astrophysics Data System (ADS)

    Valdivia, Valeska; Hennebelle, Patrick; Gérin, Maryvonne; Lesaffre, Pierre

    2016-03-01

    Context. H2 is the simplest and the most abundant molecule in the interstellar medium (ISM), and its formation precedes the formation of other molecules. Aims: Understanding the dynamical influence of the environment and the interplay between the thermal processes related to the formation and destruction of H2 and the structure of the cloud is mandatory to understand correctly the observations of H2. Methods: We performed high-resolution magnetohydrodynamical colliding-flow simulations with the adaptive mesh refinement code RAMSES in which the physics of H2 has been included. We compared the simulation results with various observations of the H2 molecule, including the column densities of excited rotational levels. Results: As a result of a combination of thermal pressure, ram pressure, and gravity, the clouds produced at the converging point of HI streams are highly inhomogeneous. H2 molecules quickly form in relatively dense clumps and spread into the diffuse interclump gas. This in particular leads to the existence of significant abundances of H2 in the diffuse and warm gas that lies in between clumps. Simulations and observations show similar trends, especially for the HI-to-H2 transition (H2 fraction vs. total hydrogen column density). Moreover, the abundances of excited rotational levels, calculated at equilibrium in the simulations, turn out to be very similar to the observed abundances inferred from FUSE results. This is a direct consequence of the presence of the H2 enriched diffuse and warm gas. Conclusions: Our simulations, which self-consistently form molecular clouds out of the diffuse atomic gas, show that H2 rapidly forms in the dense clumps and, due to the complex structure of molecular clouds, quickly spreads at lower densities. Consequently, a significant fraction of warm H2 exists in the low-density gas. This warm H2 leads to column densities of excited rotational levels close to the observed ones and probably reveals the complex intermix between

  20. Effect of inhibitors formed during wheat straw pretreatment on ethanol fermentation by Pichia stipitis.

    PubMed

    Bellido, Carolina; Bolado, Silvia; Coca, Mónica; Lucas, Susana; González-Benito, Gerardo; García-Cubero, María Teresa

    2011-12-01

    The inhibitory effect of the main inhibitors (acetic acid, furfural and 5-hydroxymethylfurfural) formed during steam explosion of wheat straw was studied through ethanol fermentations of model substrates and hydrolysates from wheat straw by Pichia stipitis. Experimental results showed that an increase in acetic acid concentration led to a reduction in ethanol productivity and complete inhibition was observed at 3.5 g/L. Furfural produced a delay on sugar consumption rates with increasing concentration and HMF did not exert a significant effect. Fermentations of the whole slurry from steam exploded wheat straw were completely inhibited by a synergistic effect due to the presence of 1.5 g/L acetic acid, 0.15 g/L furfural and 0.05 g/L HMF together with solid fraction. When using only the solid fraction from steam explosion, hydrolysates presented 0.5 g/L of acetic acid, whose fermentations have submitted promising results, providing an ethanol yield of 0.45 g ethanol/g sugars and the final ethanol concentration reached was 12.2 g/L (10.9 g ethanol/100 g DM).

  1. Candida zemplinina can reduce acetic acid produced by Saccharomyces cerevisiae in sweet wine fermentations.

    PubMed

    Rantsiou, Kalliopi; Dolci, Paola; Giacosa, Simone; Torchio, Fabrizio; Tofalo, Rosanna; Torriani, Sandra; Suzzi, Giovanna; Rolle, Luca; Cocolin, Luca

    2012-03-01

    In this study we investigated the possibility of using Candida zemplinina, as a partner of Saccharomyces cerevisiae, in mixed fermentations of must with a high sugar content, in order to reduce its acetic acid production. Thirty-five C. zemplinina strains, which were isolated from different geographic regions, were molecularly characterized, and their fermentation performances were determined. Five genetically different strains were selected for mixed fermentations with S. cerevisiae. Two types of inoculation were carried out: coinoculation and sequential inoculation. A balance between the two species was generally observed for the first 6 days, after which the levels of C. zemplinina started to decrease. Relevant differences were observed concerning the consumption of sugars, the ethanol and glycerol content, and acetic acid production, depending on which strain was used and which type of inoculation was performed. Sequential inoculation led to the reduction of about half of the acetic acid content compared to the pure S. cerevisiae fermentation, but the ethanol and glycerol amounts were also low. A coinoculation with selected combinations of S. cerevisiae and C. zemplinina resulted in a decrease of ~0.3 g of acetic acid/liter, while maintaining high ethanol and glycerol levels. This study demonstrates that mixed S. cerevisiae and C. zemplinina fermentation could be applied in sweet wine fermentation to reduce the production of acetic acid, connected to the S. cerevisiae osmotic stress response.

  2. Ethanol immunosuppression in vitro

    SciTech Connect

    Kaplan, D.R.

    1986-03-01

    Ethanol in concentrations equivalent to levels achieved by the ingestion of moderate to large amounts of alcoholic beverages has been shown to inhibit mitogen and anti-CD3 stimulated human T lymphocyte proliferation. This inhibition was monophasic suggesting that ethanol affected a single limiting component of T cell proliferation. In experiments designed to test the effect of ethanol on various aspects of proliferation, it was demonstrated that ethanol inhibited the capacity of exogenously supplied interleukin 2 to stimulate proliferation of T cells that had previously acquired interleukin 2 receptors in a monophasic, dose-dependent manner. Moreover, there was no suppression of interleukin 2 production or interleukin 2 receptor acquisition. Thus, ethanol was shown to mediate immunosuppression by a mechanism specific to one component of proliferation. Additive inhibition of T cell proliferation was seen with ethanol plus cyclosporin A which inhibits interleukin 2 production. The level of inhibition with 250 ng/ml cyclosporin A alone was equivalent to the level seen with 62 ng/ml cyclosporin A plus 20 mM (94 mg%) ethanol. Ethanol also suppressed an immune effector mechanism. NK cytotoxicity was depressed in a monophasic, dose-dependent manner. Thus, ethanol might be considered as a possible adjunct in immunosuppressive therapy.

  3. Resonant Enhancement of Ground State H2+ Formation in Low Energy Charge Transfer between Protons and H2

    NASA Astrophysics Data System (ADS)

    Andrianarijaona, V. M.; King, J. G.; Martin, M. F.; de Ruette, N.; Urbain, X.

    2013-05-01

    We investigated the charge transfer (CT) from an H2 or D2 target to various fast atomic/molecular ions for a wide span of collision energies in the laboratory frame (eV to keV). Vibrationally resolved cross sections have been obtained on a relative scale, by dissociative charge transfer of the product H2+ ions with potassium atoms, and 3-D imaging of the fragments. An absolute value of the total CT cross section has been inferred from the measured ratio of the CT yield for protons and H2+, combined with the recommended H2+ + H2 cross section (ORNL). Our results on the (H2, H+) system benchmark state-to-state calculations at 10eV and above (Phys. Rev. A 75 032703, 2007 and J. Phys. B 42, 105207 2009). In particular, they confirm the vibrational excitation mechanism responsible for the resonance at 50eV, characterized by a dominant population of the ground vibrational state of H2++. The spectra for the isotopic system (D2, H+) will be also presented along with the results of CT performed with H2++ and D2+ projectiles. Research supported by the Fund for Scientific Research - FNRS through IISN Grant No. 4.4504.10, and the National Science Foundation through Grant No. PHY-106887.

  4. H2S2014 in Kyoto: the 3rd International Conference on H2S in Biology and Medicine.

    PubMed

    Kimura, Hideo

    2015-04-30

    About 20 years ago, a pungent gas was found to be the physiological mediator of cognitive function and vascular tone. Since then, studies on hydrogen sulfide (H2S) have uncovered its numerous physiological roles such as protecting various tissues/organs from ischemia and regulating inflammation, cell growth, oxygen sensing, and senescence. These effects of H2S were extensively studied, and some of the corresponding mechanisms were also studied in detail. Previous studies on the synergistic interaction between H2S and nitric oxide (NO) have led to the discovery of several potential signaling molecules. Polysulfides are considerably potent and are one of the most active forms of H2S. H2S has a significant therapeutic potential, which is evident from the large number of novel H2S-donating compounds and substances developed for manipulating endogenous levels of H2S. The Third International Conference on H2S was held in Kyoto in June 2014. One hundred and sixty participants from 21 countries convened in Kyoto to report new advances, discuss conflicting findings, and make plans for future research. This article summarizes each oral presentation presented at the conference.

  5. Determination of the ortho to para ratio of H2Cl+ and H2O+ from submillimeter observations.

    PubMed

    Gerin, Maryvonne; de Luca, Massimo; Lis, Dariusz C; Kramer, Carsten; Navarro, Santiago; Neufeld, David; Indriolo, Nick; Godard, Benjamin; Le Petit, Franck; Peng, Ruisheng; Phillips, Thomas G; Roueff, Evelyne

    2013-10-03

    The opening of the submillimeter sky with the Herschel Space Observatory has led to the detection of new interstellar molecular ions, H2O(+), H2Cl(+), and HCl(+), which are important intermediates in the synthesis of water vapor and hydrogen chloride. In this paper, we report new observations of H2O(+) and H2Cl(+) performed with both Herschel and ground-based telescopes, to determine the abundances of their ortho and para forms separately and derive the ortho-to-para ratio. At the achieved signal-to-noise ratio, the observations are consistent with an ortho-to-para ratios of 3 for both H2O(+) and H2Cl(+), in all velocity components detected along the lines-of-sight to the massive star-forming regions W31C and W49N. We discuss the mechanisms that contribute to establishing the observed ortho-to-para ratio and point to the need for a better understanding of chemical reactions, which are important for establishing the H2O(+) and H2Cl(+) ortho-to-para ratios.

  6. Vibrational relaxation of H2O(|04> ) in collisions with H2O, Ar, H2, N2 and O2: dynamical and atmospheric implications

    NASA Astrophysics Data System (ADS)

    Barnes, P. W.; Sims, I. R.; Smith, I. W.

    2003-04-01

    It has been suggested that sequential two-photon dissociation of water might provide a mechanism for the atmospheric production of OH radical. ^1 This mechanism requires that photodissociation of vibrationally excited molecules must occur at a rate competitive with their relaxation by collisions with atmospheric gases. In this paper, we shall describe new experiments on the collisional relaxation of H_2O molecules from the highly excited mid04>± vibrational state in collisions with H_2O, Ar, H_2, N_2 and O_2. In our experiments, the mid04>^- state is populated by direct absorption of radiation from a pulsed dye laser tuned to ca. 719 nm. Evolution of the population in the (mid04>±) levels is observed using the combination of a frequency-quadrupled Nd:YAG laser, which selectively photolyses H_2O(mid04>±), and a frequency-doubled dye laser, which observes the OH(v = 0) produced via laser-induced fluorescence (LIF). The delay between the pulse from the pump laser and those from the photolysis and probe lasers was systematically varied to generate kinetic decays. The rate coefficients for relaxation obtained from these experiments, in units of cm^3 molecule-1 s-1, are: k(H_2O) = (4.1 ± 1.2) x 10-10, k(Ar) = (4.9 ± 1.1) x 10-12, k(H_2) = (6.8 ± 1.1) x 10-12, k(N_2) = (7.7 ± 1.5) x 10-12, k(O_2) = (6.7 ± 1.4) x 10-12. The results will be discussed in two contexts. First, we shall consider the implications of our new results for the interpretation of our previous experiments on the reactions of vibrationally excited H_2O with H atoms.^2 Second, we shall consider the proposal of Goss et al.1 in the light of our finding that the collisional relaxation of H_2O(mid04>±) by N_2 and O_2 is rather rapid. ^1 L. M Goss, V. Vaida, J. W. Brault and R. T. Skodje, J. Phys. Chem. A, 05, 70 (2001). ^2 (a) G. Hawthorne, P. Sharkey and I. W. M. Smith, J. Chem. Phys., 108, 4693(1998); (b) P. W. Barnes, P. Sharkey, I. R. Sims and I. W. M. Smith, Faraday Discuss. Chem. Soc., 13, 167

  7. Pyrosequencing reveals highly diverse microbial communities in microbial electrolysis cells involved in enhanced H2 production from waste activated sludge.

    PubMed

    Lu, Lu; Xing, Defeng; Ren, Nanqi

    2012-05-01

    Renewable H(2) production from a plentiful biomass, waste activated sludge (WAS), can be achieved by fermentation, but the yields are low. The use of a microbial electrolysis cell (MEC) can increase the H(2) production yields to several times that of fermentation. We have proved that the enhancement of H(2) production was due to the ability of MECs to use a wider range of organic matter in WAS than in fermentation. To support this result strongly, we here investigated the microbial community structures of WAS and anode biofilms in WAS-fed MECs. A pyrosequencing analysis based on the bacterial 16S rRNA gene showed that dominant populations in MECs were more diverse than those in WAS (inoculum and substrate) after enrichment, and there was a clear distinction between MECs and WAS in microbial community structure. Diverse acid-producing bacteria and exoelectrogens (predominance of Geobacter) were detected in MECs but they were only rarely found in WAS. It has been reported that these acid-producing bacteria can ferment various sugars and amines with acetate, propionate, and butyrate as their major by-products. This was consistent with our chemical analyses. Detected exoelectrogens are known to use these organic acids (mainly acetate) and certain sugars to directly produce current for H(2) generation at the cathodes in the MECs. Using quantitative real-time PCR, we demonstrated that a consistent feed of alkaline-pretreated WAS containing large amounts of acetate led to a predominance of acetoclastic methanogens, while hydrogenotrophic methanogens were abundant in MECs fed both raw and alkaline-pretreated WAS. Syntrophic interactions between phylogenetically diverse microbial populations in anodophilic biofilms were found to drive the efficient cascade utilization of organic matter in WAS.

  8. Mechanisms of H2S Production from Cysteine and Cystine by Microorganisms Isolated from Soil by Selective Enrichment

    PubMed Central

    Morra, Matthew J.; Dick, Warren A.

    1991-01-01

    Hydrogen sulfide (H2S) is a major component of biogenic gaseous sulfur emissions from terrestrial environments. However, little is known concerning the pathways for H2S production from the likely substrates, cysteine and cystine. A mixed microbial culture obtained from cystine-enriched soils was used in assays (50 min, 37°C) with 0.05 M Tris-HCl (pH 8.5), 25 μmol of l-cysteine, 25 μmol of l-cystine, and 0.04 μmol of pyridoxal 5′-phosphate. Sulfide was trapped in a center well containing zinc acetate, while pyruvate was measured by derivatization with 2,4-dinitrophenylhydrazine. Sulfide and total pyruvate production were 17.6 and 17.2 nmol mg of protein-1 min-1, respectively. Dithiothreitol did not alter reaction stoichiometry or the amount of H2S and total pyruvate, whereas N-ethylmaleimide reduced both H2S and total pyruvate production equally. The amount of H2S produced was reduced by 96% when only l-cystine was included as the substrate in the assay and by 15% with the addition of propargylglycine, a specific suicide inhibitor of cystathionine γ-lyase. These data indicate that the substrate for the reaction was cysteine and the enzyme responsible for H2S and pyruvate production was cysteine desulfhydrase (EC 4.4.1.1). The enzyme had a Km of 1.32 mM and was inactivated by temperatures greater than 60°C. Because cysteine is present in soil and cysteine desulfhydrase is an inducible enzyme, the potential for H2S production by this mechanism exists in terrestrial environments. The relative importance of this mechanism compared with other processes involved in H2S production from soil is unknown. PMID:16348483

  9. Potential biofuel additive from renewable sources--Kinetic study of formation of butyl acetate by heterogeneously catalyzed transesterification of ethyl acetate with butanol.

    PubMed

    Ali, Sami H; Al-Rashed, Osama; Azeez, Fadhel A; Merchant, Sabiha Q

    2011-11-01

    Butyl acetate holds great potential as a sustainable biofuel additive. Heterogeneously catalyzed transesterification of biobutanol and bioethylacetate can produce butyl acetate. This route is eco-friendly and offers several advantages over the commonly used Fischer Esterification. The Amberlite IR 120- and Amberlyst 15-catalyzed transesterification is studied in a batch reactor over a range of catalyst loading (6-12 wt.%), alcohol to ester feed ratio (1:3 to 3:1), and temperature (303.15-333.15K). A butanol mole fraction of 0.2 in the feed is found to be optimum. Amberlite IR 120 promotes faster kinetics under these conditions. The transesterifications studied are slightly exothermic. The moles of solvent sorbed per gram of catalyst decreases (ethanol>butanol>ethyl acetate>butyl acetate) with decrease in solubility parameter. The dual site models, the Langmuir Hinshelwood and Popken models, are the most successful in correlating the kinetics over Amberlite IR 120 and Amberlyst 15, respectively.

  10. Simultaneous acetic acid separation and monosaccharide concentration by reverse osmosis.

    PubMed

    Zhou, Fanglei; Wang, Cunwen; Wei, Jiang

    2013-03-01

    This study aimed to investigate the feasibility and efficiency of simultaneous acetic acid separation and sugar concentration in model lignocellulosic hydrolyzates by reverse osmosis. The effects of operation parameters such as pH, temperature, pressure and feed concentration on the solute retentions were examined with a synthetic xylose–glucose–acetic acid model solution. Results showed that the monosaccharides were almost completely rejected at above 20 bar, while the acetic acid retention increased with the increase in pH and pressure, and decreased with the temperature increase. The maximum separation factors of acetic acid over xylose and glucose reached as high as 211.5 and 228.4 at pH 2.93 (the initial pH of model lignocellulosic hydrolyzates), 40 °C and 20 bar. Furthermore, the concentration and diafiltration process were employed at optimal operation conditions. Consequently, a high sugar concentration and a beneficially lower acetic acid concentration were simultaneously achieved by reverse osmosis.

  11. Arginine-Containing Ligands Enhance H-2 Oxidation Catalyst Performance

    SciTech Connect

    Dutta, Arnab; Roberts, John A.; Shaw, Wendy J.

    2014-06-16

    In H2 fuel cells, performance depends on factors controlling turnover frequency and energy efficiency in the electrocatalytic oxidation of H2. Nature uses the hydrogenase enzymes to oxidize H2 at high turnover frequencies (up to 20,000 s-1) and low overpotentials (<100 mV), while the fastest synthetic catalyst reported to date only oxidizes H2 at 50 s-1 under 1 atm H2. Here we report a water-soluble complex incorporating the amino acid arginine, [NiII(PCy2NArg2)2]6+, that operates at 210 s-1 (180 mV overpotential) under 1 atm H2 and 144,000 s-1 (460 mV overpotential) under 133 atm H2. The complex functions from pH 0-14 with rates increasing at lower pH values. The arginine groups impart water solubility and play a critical role in enhancing turnover frequency, most consistent with an intramolecular Arg-Arg interaction that controls the structure of the catalyst active site. This work was funded by the Office of Science Early Career Research Program through the US DOE, BES (AD, WJS), and the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US DOE, BES (JASR). PNNL is operated by Battelle for the US DOE.

  12. Metabolism of (2-14C)acetate and its use in assessing hepatic Krebs cycle activity and gluconeogenesis

    SciTech Connect

    Schumann, W.C.; Magnusson, I.; Chandramouli, V.; Kumaran, K.; Wahren, J.; Landau, B.R. )

    1991-04-15

    To examine the fate of the carbons of acetate and to evaluate the usefulness of labeled acetate in assessing intrahepatic metabolic processes during gluconeogenesis, (2-14C)acetate, (2-14C)ethanol, and (1-14C)ethanol were infused into normal subjects fasted 60 h and given phenyl acetate. Distributions of 14C in the carbons of blood glucose and glutamate from urinary phenylacetylglutamine were determined. With (2-14C)acetate and (2-14C)ethanol, carbon 1 of glucose had about twice as much 14C as carbon 3. Carbon 2 of glutamate had about twice as much 14C as carbon 1 and one-half to one-third as much as carbon 4. There was only a small amount in carbon 5. These distributions are incompatible with the metabolism of (2-14C)acetate being primarily in liver. Therefore, (2-14C)acetate cannot be used to study Krebs cycle metabolism in liver and in relationship to gluconeogenesis, as has been done. The distributions can be explained by: (a) fixation of 14CO2 from (2-14C)acetate in the formation of the 14C-labeled glucose and glutamate in liver and (b) the formation of 14C-labeled glutamate in a second site, proposed to be muscle. (1,3-14C)Acetone formation from the (2-14C)acetate does not contribute to the distributions, as evidenced by the absence of 14C in carbons 2-4 of glutamate after (1-14C)ethanol administration.

  13. Acetate induced enhancement of photocatalytic hydrogen peroxide production from oxalic acid and dioxygen.

    PubMed

    Yamada, Yusuke; Nomura, Akifumi; Miyahigashi, Takamitsu; Ohkubo, Kei; Fukuzumi, Shunichi

    2013-05-09

    The addition of acetate ion to an O2-saturated mixed solution of acetonitrile and water containing oxalic acid as a reductant and 2-phenyl-4-(1-naphthyl)quinolinium ion (QuPh(+)-NA) as a photocatalyst dramatically enhanced the turnover number of hydrogen peroxide (H2O2) production. In this photocatalytic H2O2 production, a base is required to facilitate deprotonation of oxalic acid forming oxalate dianion, which acts as an actual electron donor, whereas a Brønsted acid is also necessary to protonate O2(•-) for production of H2O2 by disproportionation. The addition of acetate ion to a reaction solution facilitates both the deprotonation of oxalic acid and the protonation of O2(•-) owing to a pH buffer effect. The quantum yield of the photocatalytic H2O2 production under photoirradiation (λ = 334 nm) of an O2-saturated acetonitrile-water mixed solution containing acetate ion, oxalic acid and QuPh(+)-NA was determined to be as high as 0.34, which is more than double the quantum yield obtained by using oxalate salt as an electron donor without acetate ion (0.14). In addition, the turnover number of QuPh(+)-NA reached more than 340. The reaction mechanism and the effect of solvent composition on the photocatalytic H2O2 production were scrutinized by using nanosecond laser flash photolysis.

  14. H2 in low-ionization structures of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Akras, Stavros; Gonçalves, Denise R.; Ramos-Larios, Gerardo

    2017-02-01

    We report the detection of near-IR H2 emission from the low-ionization structures (knots) in two planetary nebulae. The deepest ever high-angular-resolution H2 (1-0) S(1) at 2.122 μm, H2 (2-1) S(1) at 2.248 μm and Brγ images of K 4-47 and NGC 7662, obtained using the Near InfraRed Imager and Spectrometer (NIRI) at Gemini-North, are analysed here. K 4-47 reveals a remarkable highly collimated bipolar structure not only in the optical but also in the molecular hydrogen emission. The H2 emission emanates from the walls of the bipolar outflows and also from the pair of knots at the tip of the outflows. The H2 (1-0) S(1)/(2-1) S(1) line ratio ranges from ∼7 to ∼10, suggesting the presence of shock interactions. Our findings can be explained by the interaction of a jet/bullet ejected from the central star with the surrounding asymptotic giant branch material. The strongest H2 line, (1-0) S(1), is also detected in several low-ionization knots located at the periphery of the elliptical planetary nebula NGC 7662, but only four of these knots are detected in the H2 (2-1) S(1) line. These four knots exhibit an H2 line ratio between 2 and 3.5, which suggests that the emission is caused by the UV ionizing flux of the central star. Our data confirm the presence of H2 gas in both fast- and slow-moving low-ionization knots, which has only been confirmed before in the nearby Helix nebula and Hu 1-2. Overall, the low-ionization structures of planetary nebulae are found to have similar traits to photodissociation regions.

  15. Pyruvate protects pathogenic spirochetes from H2O2 killing.

    PubMed

    Troxell, Bryan; Zhang, Jun-Jie; Bourret, Travis J; Zeng, Melody Yue; Blum, Janice; Gherardini, Frank; Hassan, Hosni M; Yang, X Frank

    2014-01-01

    Pathogenic spirochetes cause clinically relevant diseases in humans and animals, such as Lyme disease and leptospirosis. The causative agent of Lyme disease, Borrelia burgdorferi, and the causative agent of leptospirosis, Leptospria interrogans, encounter reactive oxygen species (ROS) during their enzootic cycles. This report demonstrated that physiologically relevant concentrations of pyruvate, a potent H2O2 scavenger, and provided passive protection to B. burgdorferi and L. interrogans against H2O2. When extracellular pyruvate was absent, both spirochetes were sensitive to a low dose of H2O2 (≈0.6 µM per h) generated by glucose oxidase (GOX). Despite encoding a functional catalase, L. interrogans was more sensitive than B. burgdorferi to H2O2 generated by GOX, which may be due to the inherent resistance of B. burgdorferi because of the virtual absence of intracellular iron. In B. burgdorferi, the nucleotide excision repair (NER) and the DNA mismatch repair (MMR) pathways were important for survival during H2O2 challenge since deletion of the uvrB or the mutS genes enhanced its sensitivity to H2O2 killing; however, the presence of pyruvate fully protected ΔuvrB and ΔmutS from H2O2 killing further demonstrating the importance of pyruvate in protection. These findings demonstrated that pyruvate, in addition to its classical role in central carbon metabolism, serves as an important H2O2 scavenger for pathogenic spirochetes. Furthermore, pyruvate reduced ROS generated by human neutrophils in response to the Toll-like receptor 2 (TLR2) agonist zymosan. In addition, pyruvate reduced neutrophil-derived ROS in response to B. burgdorferi, which also activates host expression through TLR2 signaling. Thus, pathogenic spirochetes may exploit the metabolite pyruvate, present in blood and tissues, to survive H2O2 generated by the host antibacterial response generated during infection.

  16. Pyruvate Protects Pathogenic Spirochetes from H2O2 Killing

    PubMed Central

    Troxell, Bryan; Zhang, Jun-Jie; Bourret, Travis J.; Zeng, Melody Yue; Blum, Janice; Gherardini, Frank; Hassan, Hosni M.; Yang, X. Frank

    2014-01-01

    Pathogenic spirochetes cause clinically relevant diseases in humans and animals, such as Lyme disease and leptospirosis. The causative agent of Lyme disease, Borrelia burgdorferi, and the causative agent of leptospirosis, Leptospria interrogans, encounter reactive oxygen species (ROS) during their enzootic cycles. This report demonstrated that physiologically relevant concentrations of pyruvate, a potent H2O2 scavenger, and provided passive protection to B. burgdorferi and L. interrogans against H2O2. When extracellular pyruvate was absent, both spirochetes were sensitive to a low dose of H2O2 (≈0.6 µM per h) generated by glucose oxidase (GOX). Despite encoding a functional catalase, L. interrogans was more sensitive than B. burgdorferi to H2O2 generated by GOX, which may be due to the inherent resistance of B. burgdorferi because of the virtual absence of intracellular iron. In B. burgdorferi, the nucleotide excision repair (NER) and the DNA mismatch repair (MMR) pathways were important for survival during H2O2 challenge since deletion of the uvrB or the mutS genes enhanced its sensitivity to H2O2 killing; however, the presence of pyruvate fully protected ΔuvrB and ΔmutS from H2O2 killing further demonstrating the importance of pyruvate in protection. These findings demonstrated that pyruvate, in addition to its classical role in central carbon metabolism, serves as an important H2O2 scavenger for pathogenic spirochetes. Furthermore, pyruvate reduced ROS generated by human neutrophils in response to the Toll-like receptor 2 (TLR2) agonist zymosan. In addition, pyruvate reduced neutrophil-derived ROS in response to B. burgdorferi, which also activates host expression through TLR2 signaling. Thus, pathogenic spirochetes may exploit the metabolite pyruvate, present in blood and tissues, to survive H2O2 generated by the host antibacterial response generated during infection. PMID:24392147

  17. Photosynthetic H2 metabolism in Chlamydomonas reinhardtii (unicellular green algae).

    PubMed

    Melis, Anastasios

    2007-10-01

    Unicellular green algae have the ability to operate in two distinctly different environments (aerobic and anaerobic), and to photosynthetically generate molecular hydrogen (H2). A recently developed metabolic protocol in the green alga Chlamydomonas reinhardtii permitted separation of photosynthetic O2-evolution and carbon accumulation from anaerobic consumption of cellular metabolites and concomitant photosynthetic H2-evolution. The H2 evolution process was induced upon sulfate nutrient deprivation of the cells, which reversibly inhibits photosystem-II and O2-evolution in their chloroplast. In the absence of O2, and in order to generate ATP, green algae resorted to anaerobic photosynthetic metabolism, evolved H2 in the light and consumed endogenous substrate. This study summarizes recent advances on green algal hydrogen metabolism and discusses avenues of research for the further development of this method. Included is the mechanism of a substantial tenfold starch accumulation in the cells, observed promptly upon S-deprivation, and the regulated starch and protein catabolism during the subsequent H2-evolution. Also discussed is the function of a chloroplast envelope-localized sulfate permease, and the photosynthesis-respiration relationship in green algae as potential tools by which to stabilize and enhance H2 metabolism. In addition to potential practical applications of H2, approaches discussed in this work are beginning to address the biochemistry of anaerobic H2 photoproduction, its genes, proteins, regulation, and communication with other metabolic pathways in microalgae. Photosynthetic H2 production by green algae may hold the promise of generating a renewable fuel from nature's most plentiful resources, sunlight and water. The process potentially concerns global warming and the question of energy supply and demand.

  18. Anti-inflammatory activity of four solvent fractions of ethanol extract of Mentha spicata L. investigated on acute and chronic inflammation induced rats.

    PubMed

    Arumugam, P; Priya, N Gayatri; Subathra, M; Ramesh, A

    2008-07-01

    Anti-inflammatory effects of four solvent fractions of ethanol extract of Mentha spicata were evaluated in acute and chronic inflammation induced in Wistar albino rats. Lipid peroxidation (LPO) and some antioxidants produced during chronic inflammation were quantitated. Hexane (320mg/kg of body weight in 25% DMSO), chloroform (320mg/kg body weight in 25% DMSO), ethyl acetate (160mg/kg body weight in 25% DMSO), aqueous (320mg/kg of body weight in ddH(2)O) fractions, two negative control groups (25% DMSO and ddH(2)O) and two anti-inflammatory drugs (Diclofenac: 25mg/kg of body weight; Indomethacin: 10mg/kg of body weight both in ddH(2)O) were administered by oral intubations to the eight groups of rats consisting six animals, each. In acute study, 1% carrageenan was injected subcutaneously in the sub-plantar region of the right hind paw after 1h of administration of test doses. The increased paw edema was measured at 0.5, 1, 2, 4, 8, 16 and 24h intervals. In the chronic study, the oral administration was carried out for seven consecutive days. On eighth day, four sterile cotton pellets (50mg each) were implanted subcutaneously in the dorsal region of the rats. On the sixteenth day, the rats were sacrificed and the cotton pellets with granulomatous tissue were dissected out and weighed (fresh and dry). Both in chronic and acute inflammation, ethyl acetate (EAF) and aqueous fraction (AF) were effective. EAF is comparable with the positive standards in chronic inflammation. The results indicate that EAF's anti-inflammatory activity is largely due to its ability to modulate in vivo antioxidants.

  19. Lifetime studies in H2/Br2 fuel cells

    NASA Astrophysics Data System (ADS)

    Barna, G. G.; Frank, S. N.; Teherani, T. H.; Weedon, L. D.

    1984-09-01

    A fully computerized system has been set up for the life testing of H2 electrodes in 48 percent HBr, and of H2/Br2 fuel cells. Given a fuel cell design with dry H2 and no anolyte loop, the prime parameters influencing the operating lifetime are the hydrophobicity of the anode and the electrolyte transport property of the membrane. A systematic optimization of all the parameters has generated fuel cells that have operated for 10,000h at 2 A/sq in., with no significant degradation.

  20. The Anharmonic Force Field of BeH2 Revisited

    NASA Technical Reports Server (NTRS)

    Martin, Jan M. L.; Lee, Timothy J.

    2003-01-01

    The anharmonic force field of BeH2 has been calculated near the basis set and n-particle space limits. The computed antisymmetric stretch frequencies of BeH2 and BeD2 are in excellent agreement with recent high-resolution gas-phase measurements. The agreement between theory and experiment for the other spectroscopic constants is also excellent, except for omega(sub 3) and X(sub 33) for BeH2 and G(sub 22) for BeD2. It is concluded that further experimental work is needed in order to resolve these discrepancies.

  1. Histamine H2 receptor - Involvement in gastric ulceration

    NASA Technical Reports Server (NTRS)

    Brown, P. A.; Vernikos-Danellis, J.; Brown, T. H.

    1976-01-01

    The involvement of the H1 and H2 receptors for histamine in the pathogenesis of gastric ulcers was investigated in rats. Metiamide, an H2 receptor antagonist, reliably reduced ulceration produced by stress alone or by a combination of stress and aspirin. In contrast, pyrilamine, which blocks only the H1 receptor, was without effect under these same conditions. The results support the hypothesis that histamine mediates both stress and stress plus aspirin induced ulceration by a mechanism involving the H2 receptor.

  2. Effects of H2S on molten carbonate fuel cells

    NASA Astrophysics Data System (ADS)

    Remick, R. J.; Anderson, G. L.

    1984-04-01

    The results of a literature survey conducted by the Institute of Gas Technology (IGT) under Phase 1 of a multiphase program to investigate and identify the mechanism(s) responsible for molten carbonate fuel cell (MCFC) performance losses when operating on sulfur containing gases are discussed. The objective was twofold: to review the reported data on the interaction of H2S with nickel containing materials; and to review reported investigations on the specific effects of H2S on the electrochemical oxidation of H2 in MCFC. The ultimate goal of the literature review was to determine the poisoning mechanism.

  3. A global potential energy surface for ArH2

    NASA Technical Reports Server (NTRS)

    Schwenke, David W.; Walch, Stephen P.; Taylor, Peter R.

    1992-01-01

    We describe a simple analytic representation of the ArH2 potential energy surface which well reproduces the results of extensive ab initio electronic structure calculations. The analytic representation smoothly interpolates between the dissociated H2 and strong bonding limits. In the fitting process, emphasis is made on accurately reproducing regions of the potential expected to be important for high temperature (ca. 3000 K) collision processes. Overall, the anisotropy and H2 bond length dependence of the analytic representation well reproduce the input data.

  4. A global potential energy surface for ArH2

    NASA Technical Reports Server (NTRS)

    Schwenke, David W.; Walch, Stephen P.; Taylor, Peter R.

    1993-01-01

    We describe a simple analytic representation of the ArH2 potential energy surface which well reproduces the results of extensive ab initio electronic structure calculations. The analytic representation smoothly interpolates between the dissociated H2 and strong bonding limits. In the fitting process, emphasis is made on accurately reproducing regions of the potential expected to be important for high temperature (ca. 3000 K) collision processes. Overall, the anisotropy and H2 bond length dependence of the analytic representation well reproduce the input data.

  5. In vitro effects of ethanol and mouthrinse on permeability in an oral buccal mucosal tissue construct.

    PubMed

    Koschier, Francis; Kostrubsky, Vsevolod; Toole, Colleen; Gallo, Michael A

    2011-10-01

    The current study investigated the influence of ethanol and ethanol-containing mouthrinses on model chemical permeability in an in vitro oral buccal mucosal construct (EpiOral, ORL-200, MatTek). Innate ethanol transport and metabolism in the tissue construct was also studied. Caffeine flux in buccal tissue was measured after pre-treatment with < 26.9% ethanol or Listerine(®) products under conditions modeling a typical mouthwash rinsing. Specifically, a 30s exposure to alcohol products followed by a 10h non-treatment phase and then a second 30s exposure prior to addition of caffeine. At 10min specific intervals, media was collected from the basal part of the tissue insert for HPLC analysis of caffeine. The results demonstrated no increase in caffeine flux due to prior exposure to either ethanol or Listerine(®), and the flux and permeability constants were derived from the linear phase. No cytotoxicity or histopathological effects were observed in these tissues. We also studied the transepithelial transport and metabolism of ethanol in these tissues. Transport of ethanol was concentration-dependent with rate of diffusion proportional to the concentration gradient across the membrane. The potential metabolism of ethanol in the EpiOral construct was addressed by analyzing the remaining level of ethanol after incubation and de novo accumulation of acetaldehyde or acetic acid in culture media. Incubation for 30min incubation resulted in no change in ethanol level up to 2000mM, the highest concentration tested. No acetaldehyde or acetic acid was detected in culture media. In conclusion, ethanol and ethanol-containing mouthrinse treatment modeled after a typical daily mouthrinse pattern had no apparent effect on the permeability of the standard model chemical, caffeine. This exposure also had no effect on the viability of the tissue construct or histopathology, and uptake of ethanol was rapid into the tissue construct.

  6. Biological production of ethanol from coal. Final report

    SciTech Connect

    Not Available

    1992-12-01

    Due to the abundant supply of coal in the United States, significant research efforts have occurred over the past 15 years concerning the conversion of coal to liquid fuels. Researchers at the University of Arkansas have concentrated on a biological approach to coal liquefaction, starting with coal-derived synthesis gas as the raw material. Synthesis gas, a mixture of CO, H{sub 2}, CO{sub 2}, CH{sub 4} and sulfur gases, is first produced using traditional gasification techniques. The CO, CO{sub 2} and H{sub 2} are then converted to ethanol using a bacterial culture of Clostridium 1jungdahlii. Ethanol is the desired product if the resultant product stream is to be used as a liquid fuel. However, under normal operating conditions, the ``wild strain`` produces acetate in favor of ethanol in conjunction with growth in a 20:1 molar ratio. Research was performed to determine the conditions necessary to maximize not only the ratio of ethanol to acetate, but also to maximize the concentration of ethanol resulting in the product stream.

  7. Efficient C2 functionalisation of 2H-2-imidazolines.

    PubMed

    Bon, Robin S; Sprenkels, Nanda E; Koningstein, Manoe M; Schmitz, Rob F; de Kanter, Frans J J; Dömling, Alexander; Groen, Marinus B; Orru, Romano V A

    2008-01-07

    Alkylation and oxidation of 2H-2-imidazolines, followed by regioselective deprotection, thionation and microwave-assisted Liebeskind-Srogl reaction, efficiently led to 2-aryl-2-imidazolines as new analogues of p53-hdm2 interaction inhibitors (Nutlins).

  8. Metal-graphene heterojunction modulation via H2 interaction

    NASA Astrophysics Data System (ADS)

    Cadore, A. R.; Mania, E.; de Morais, E. A.; Watanabe, K.; Taniguchi, T.; Lacerda, R. G.; Campos, L. C.

    2016-07-01

    Combining experiment and theory, we investigate how a naturally created heterojunction (pn junction) at a graphene and metallic contact interface is modulated via interaction with molecular hydrogen (H2). Due to an electrostatic interaction, metallic electrodes induce pn junctions in graphene, leading to an asymmetrical resistance in electronic transport for electrons and holes. We report that the asymmetry in the resistance can be tuned in a reversible manner by exposing graphene devices to H2. The interaction between the H2 and graphene occurs solely at the graphene-contact pn junction and induces a modification on the electrostatic interaction between graphene and metallic contacts. We explain the experimental data with theory providing information concerning the length of the heterojunction and how it changes as a function of H2 adsorption. Our results are valuable for understanding the nature of the metal-graphene interfaces and have potential application for selective sensors of molecular hydrogen.

  9. Outbursts of H2O in Comet P/Halley

    NASA Astrophysics Data System (ADS)

    Larson, H. P.; Hu, H.-Y.; Mumma, M. J.; Weaver, H. A.

    1990-07-01

    Comet Halley gas-production monitoring efforts in March 1986 with the NASA Kuiper Airborne Observatory's Fourier transform spectrometer have indicated rapid temporal variations in H2O emissions; a continuous record of an H2O outburst was thus obtained. The event, in which H2O brightness increased by a factor of 2.2 in less than 10 min, is ascribable to an energetic process in the nucleus whose character may have been that of amorphous H2O ice crystallization, chemical explosion, thermal stress, or a compressed gas pocket. The timing and energy of the event appear to require an internal energy source; amorphous ice crystallization is held to be most consistent with compositional and thermal models of cometary nuclei as well as the observations.

  10. Phonon-mediated nuclear spin relaxation in H2O

    NASA Astrophysics Data System (ADS)

    Yamakawa, Koichiro; Azami, Shinya; Arakawa, Ichiro

    2017-03-01

    A theoretical model of the phonon-mediated nuclear spin relaxation in H2O trapped by cryomatrices has been established for the first time. In order to test the validity of this model, we measured infrared spectra of H2O trapped in solid Ar, which showed absorption peaks due to rovibrational transitions of ortho- and para-H2O in the spectral region of the bending vibration. We monitored the time evolution of the spectra and analyzed the rotational relaxation associated with the nuclear spin flip to obtain the relaxation rates of H2O at temperatures of 5-15 K. Temperature dependence of the rate is discussed in terms of the devised model.

  11. Fermentation of Soybean Meal Hydrolyzates with Saccharomyces cerevisiae and Zymomonas mobilis for Ethanol Production.

    PubMed

    Luján-Rhenals, Deivis E; Morawicki, Rubén O; Gbur, Edward E; Ricke, Steven C

    2015-07-01

    Most of the ethanol currently produced by fermentation is derived from sugar cane, corn, or beets. However, it makes good ecological and economic sense to use the carbohydrates contained in by-products and coproducts of the food processing industry for ethanol production. Soybean meal, a co-product of the production of soybean oil, has a relatively high carbohydrate content that could be a reasonable substrate for ethanol production after fermentable sugars are released via hydrolysis. In this research, the capability of Saccharomyces cerevisiae NRRL Y-2233 and Zymomonas mobilis subsp. mobilis NRRL B-4286 to produce ethanol was evaluated using soybean meal hydrolyzates as substrates for the fermentation. These substrates were produced from the dilute-acid hydrolysis of soybean meal at 135 °C for 45 min with 0, 0.5%, 1.25%, and 2% H2 SO4 and at 120 °C for 30 min with 1.25% H2 SO4 . Kinetic parameters of the fermentation were estimated using the logistic model. Ethanol production using S. cerevisiae was highest with the substrates obtained at 135 °C, 45 min, and 0.5% H2 SO4 and fermented for 8 h, 8 g/L (4 g ethanol/100 g fresh SBM), while Z. mobilis reached its maximum ethanol production, 9.2 g/L (4.6 g ethanol/100 g fresh SBM) in the first 20 h of fermentation with the same hydrolyzate.

  12. Ethanol tolerance in bacteria.

    PubMed

    Ingram, L O

    1990-01-01

    The adverse effects of ethanol on bacterial growth, viability, and metabolism are caused primarily by ethanol-induced leakage of the plasma membrane. This increase in membrane leakage is consistent with known biophysical properties of membranes and ethanolic solutions. The primary actions of ethanol result from colligative effects of the high molar concentrations rather than from specific interactions with receptors. The ethanol tolerance of growth in different microorganisms appears to result in large part from adaptive and evolutionary changes in cell membrane composition. Different cellular activities vary in their tolerance to ethanol. Therefore, it is essential that the aspect of cellular function under study be specifically defined and that comparisons of ethanol tolerance among systems share this common definition. Growth is typically one of the most sensitive cellular activities to inhibition by ethanol, followed by survival, or loss of reproductive ability. Glycolysis is the most resistant of these three activities. Since glycolysis is an exergonic process, a cell need not be able to grow or remain viable for glycolysis to occur.

  13. Glitters of warm H2 in cold diffuse molecular gas

    NASA Astrophysics Data System (ADS)

    Falgarone, Edith; Boulanger, Francois; Combes, Francoise; Pineau Des Forets, Guillaume; Verstraete, Laurent

    2007-05-01

    Cold molecular hydrogen, a dominant gas fraction in galaxies, does not radiate due to the symmetry of the molecule. The only tracers of cold H2, the rotational lines of CO and dust thermal emission operate only in metal-rich environments. By detecting the lowest rotational lines of H2 at unexpected levels in the cold diffuse medium of the Galaxy, ISO-SWS has challenged the traditional view of the interstellar medium (ISM) by possibly revealing the existence of tiny gas fractions within the cold ISM, warm enough to excite H2 lines. The heating source of H2 there is the intermittent dissipation of supersonic turbulence, pervading the entire ISM. These glitters of H2 line emission may become the unique tracers of cold H2 in low metallicity environments. Given the fundamental importance of probing large hidden masses of gas in galaxies, for their implication on galaxy dynamics, star formation thresholds in metal-poor environments, and the hypothesis of H2 as baryonic dark matter in galaxies, the present SST/IRS proposal is dedicated to further search of this still elusive emission. The proposed observations consist in several IRS LL pointings along the major axis of two external galaxies with massive HI disks extending far beyond their optical radius, and for which the HI rotation curve cannot be accounted for by the stellar and visible gas components. These spectra also observed in the direction of the galaxy nuclei, are meant to allow the separation between the H2 emission with stellar-type excitation from that originating in gas heated by turbulence dissipation. The goal of the proposal is to strenghten the existence of pockets of warm H2 disseminated in the cold diffuse medium of galaxies. These glitters of warm H2 would be a new tracer of hitherto undetected amounts of cold H2 in low metallicity environments, and, as a more exploratory facet, might probe the presence of large amounts of baryonic dark matter in galaxies in the form of cold molecular hydrogen.

  14. Investigation of H2 and H2S adsorption on niobium- and copper-doped palladium surfaces.

    PubMed

    Ozdogan, Ekin; Wilcox, Jennifer

    2010-10-14

    Alloying or doping Pd may be an option for overcoming sulfur poisoning. The current investigation probes the mechanism associated with sulfur binding to determine if Nb and Cu are appropriate doping metals. In this study, the effect of doping Pd with Cu or Nb on the binding strength of H(2) and H(2)S was investigated using plane-wave density functional theory-based electronic structure calculations to determine mechanisms of adsorption. Results of this work indicate that for pure Pd and Pd-doped surfaces, H(2) dissociates with the H atoms most stable on the fcc-fcc site. The overall d-band centers calculated for H(2) adsorption at the fcc-fcc site for the pure and doped-Pd surfaces indicate that the H(2) adsorption strength trend is Pd > Cu > Nb. Regarding H(2)S adsorption on Pd and Pd-doped surfaces, it was found that Cu has a lower affinity for H(2)S compared to Pd and Nb. The calculation of the local density of states of the s-, p-, and d-orbitals of the adsorbate-surface complex reveals an increase in the occupation of s-and p-states of the adsorbate and d-states of the dopant metals upon adsorption. In addition, the H(2)S binding trend is found to be Cu < Pd < Nb, with the doped-Cu surfaces exhibiting the weakest binding and doped-Nb surfaces the strongest binding. Geometry comparisons of each H(2)S-adsorbed complex shows that the hydrogen atoms are located closest to the surface in the case of Nb, indicating that the strong H-surface interaction leads to the enhanced adsorption behavior, rather than the S-surface interaction; in fact, the sulfur atom is located furthest from the surface doped with Nb.

  15. Nitrate addition to groundwater impacted by ethanol-blended fuel accelerates ethanol removal and mitigates the associated metabolic flux dilution and inhibition of BTEX biodegradation.

    PubMed

    Corseuil, Henry Xavier; Gomez, Diego E; Schambeck, Cássio Moraes; Ramos, Débora Toledo; Alvarez, Pedro J J

    2015-03-01

    A comparison of two controlled ethanol-blended fuel releases under monitored natural attenuation (MNA) versus nitrate biostimulation (NB) illustrates the potential benefits of augmenting the electron acceptor pool with nitrate to accelerate ethanol removal and thus mitigate its inhibitory effects on BTEX biodegradation. Groundwater concentrations of ethanol and BTEX were measured 2 m downgradient of the source zones. In both field experiments, initial source-zone BTEX concentrations represented less than 5% of the dissolved total organic carbon (TOC) associated with the release, and measurable BTEX degradation occurred only after the ethanol fraction in the multicomponent substrate mixture decreased sharply. However, ethanol removal was faster in the nitrate amended plot (1.4 years) than under natural attenuation conditions (3.0 years), which led to faster BTEX degradation. This reflects, in part, that an abundant substrate (ethanol) can dilute the metabolic flux of target pollutants (BTEX) whose biodegradation rate eventually increases with its relative abundance after ethanol is preferentially consumed. The fate and transport of ethanol and benzene were accurately simulated in both releases using RT3D with our general substrate interaction module (GSIM) that considers metabolic flux dilution. Since source zone benzene concentrations are relatively low compared to those of ethanol (or its degradation byproduct, acetate), our simulations imply that the initial focus of cleanup efforts (after free-product recovery) should be to stimulate the degradation of ethanol (e.g., by nitrate addition) to decrease its fraction in the mixture and speed up BTEX biodegradation.

  16. Nitrate addition to groundwater impacted by ethanol-blended fuel accelerates ethanol removal and mitigates the associated metabolic flux dilution and inhibition of BTEX biodegradation

    NASA Astrophysics Data System (ADS)

    Corseuil, Henry Xavier; Gomez, Diego E.; Schambeck, Cássio Moraes; Ramos, Débora Toledo; Alvarez, Pedro J. J.

    2015-03-01

    A comparison of two controlled ethanol-blended fuel releases under monitored natural attenuation (MNA) versus nitrate biostimulation (NB) illustrates the potential benefits of augmenting the electron acceptor pool with nitrate to accelerate ethanol removal and thus mitigate its inhibitory effects on BTEX biodegradation. Groundwater concentrations of ethanol and BTEX were measured 2 m downgradient of the source zones. In both field experiments, initial source-zone BTEX concentrations represented less than 5% of the dissolved total organic carbon (TOC) associated with the release, and measurable BTEX degradation occurred only after the ethanol fraction in the multicomponent substrate mixture decreased sharply. However, ethanol removal was faster in the nitrate amended plot (1.4 years) than under natural attenuation conditions (3.0 years), which led to faster BTEX degradation. This reflects, in part, that an abundant substrate (ethanol) can dilute the metabolic flux of target pollutants (BTEX) whose biodegradation rate eventually increases with its relative abundance after ethanol is preferentially consumed. The fate and transport of ethanol and benzene were accurately simulated in both releases using RT3D with our general substrate interaction module (GSIM) that considers metabolic flux dilution. Since source zone benzene concentrations are relatively low compared to those of ethanol (or its degradation byproduct, acetate), our simulations imply that the initial focus of cleanup efforts (after free-product recovery) should be to stimulate the degradation of ethanol (e.g., by nitrate addition) to decrease its fraction in the mixture and speed up BTEX biodegradation.

  17. Metal Oxide/Zeolite Combination Absorbs H2S

    NASA Technical Reports Server (NTRS)

    Voecks, Gerald E.; Sharma, Pramod K.

    1989-01-01

    Mixed copper and molybdenum oxides supported in pores of zeolite found to remove H2S from mixture of gases rich in hydrogen and steam, at temperatures from 256 to 538 degree C. Absorber of H2S needed to clean up gas streams from fuel processors that incorporate high-temperature steam reformers or hydrodesulfurizing units. Zeolites chosen as supporting materials because of their high porosity, rigidity, alumina content, and variety of both composition and form.

  18. Interaction—Induced Spectroscopy of H2 in the Fullerenes

    NASA Astrophysics Data System (ADS)

    Lewis, John Courtenay; Herman, Roger M.

    2006-11-01

    Carbon nanostructures of various sorts have been the subject of intensive research since their discoveries in the latter part of the 20th century. Much of this research has been motivated by the intrinsic interest of these structures, though their potential as hydrogen storage media has also attracted attention. It was realized that the carbon-hydrogen interactions in these media would induce dipole moments which might lead to observable absorption of infrared spectra, and this work will be reviewed and extended in this paper. The fundamental vibration-rotation spectrum, of H2 in a fcc C60 lattice (fullerite) at room temperature was first observed by S. A. FitzGerald and coworkers, who have subsequently extended their observations to near liquid nitrogen temperatures. Herman and Lewis have discussed the theoretical aspects of H2 in carbon nanotube bundles and in fullerite. We have developed a detailed theory for the spectrum of H2 in fullerite. This theory assumes that the H2 - C potential can be accurately approximated by an exp-6 potential, the parameters of which are then obtained by fitting the line frequencies in FitzGerald's spectra. We have also obtained a model for the H2 induced dipole moment based on the calculations of Frommhold and coworkers on the induced dipole in H2 - He. With one adjustable parameter this model gives a good account of the observed intensities. In work to date the line width has been taken as an empirical parameter. However, the line width is in principal determinable from the H2 - C potential and induced dipole moment, together with the known properties of the phonon modes in fullerite. We conclude this paper with a discussion of the line width problem for H2 in fullerite.

  19. The interstellar chemistry of H2C3O isomers.

    PubMed

    Loison, Jean-Christophe; Agúndez, Marcelino; Marcelino, Núria; Wakelam, Valentine; Hickson, Kevin M; Cernicharo, José; Gerin, Maryvonne; Roueff, Evelyne; Guélin, Michel

    2016-03-11

    We present the detection of two H2C3O isomers, propynal and cyclopropenone, toward various starless cores and molecular clouds, together with upper limits for the third isomer propadienone. We review the processes controlling the abundances of H2C3O isomers in interstellar media showing that the reactions involved are gas-phase ones. We show that the abundances of these species are controlled by kinetic rather than thermodynamic effects.

  20. Interaction energy and the shift in OH stretch frequency on hydrogen bonding for the H2O --> H2O, CH3OH --> H2O, and H2O --> CH3OH dimers.

    PubMed

    Campen, Richard Kramer; Kubicki, James D

    2010-04-15

    The ability to use calculated OH frequencies to assign experimentally observed peaks in hydrogen bonded systems hinges on the accuracy of the calculation. Here we test the ability of several commonly employed model chemistries--HF, MP2, and several density functionals paired with the 6-31+G(d) and 6-311++G(d,p) basis sets--to calculate the interaction energy (D(e)) and shift in OH stretch fundamental frequency on dimerization (delta(nu)) for the H(2)O --> H(2)O, CH(3)OH --> H(2)O, and H(2)O --> CH(3)OH dimers (where for X --> Y, X is the hydrogen bond donor and Y the acceptor). We quantify the error in D(e) and delta(nu) by comparison to experiment and high level calculation and, using a simple model, evaluate how error in D(e) propagates to delta(nu). We find that B3LYP and MPWB1K perform best of the density functional methods studied, that their accuracy in calculating delta(nu) is approximately 30-50 cm(-1) and that correcting for error in D(e) does little to heighten agreement between the calculated and experimental delta(nu). Accuracy of calculated delta(nu) is also shown to vary as a function of hydrogen bond donor: while the PBE and TPSS functionals perform best in the calculation of delta(nu) for the CH(3)OH --> H(2)O dimer their performance is relatively poor in describing H(2)O --> H(2)O and H(2)O --> CH(3)OH.

  1. Are CO Observations of Interstellar Clouds Tracing the H2?

    NASA Astrophysics Data System (ADS)

    Federrath, Christoph; Glover, S. C. O.; Klessen, R. S.; Mac Low, M.

    2010-01-01

    Interstellar clouds are commonly observed through the emission of rotational transitions from carbon monoxide (CO). However, the abundance ratio of CO to molecular hydrogen (H2), which is the most abundant molecule in molecular clouds is only about 10-4. This raises the important question of whether the observed CO emission is actually tracing the bulk of the gas in these clouds, and whether it can be used to derive quantities like the total mass of the cloud, the gas density distribution function, the fractal dimension, and the velocity dispersion--size relation. To evaluate the usability and accuracy of CO as a tracer for H2 gas, we generate synthetic observations of hydrodynamical models that include a detailed chemical network to follow the formation and photo-dissociation of H2 and CO. These three-dimensional models of turbulent interstellar cloud formation self-consistently follow the coupled thermal, dynamical and chemical evolution of 32 species, with a particular focus on H2 and CO (Glover et al. 2009). We find that CO primarily traces the dense gas in the clouds, however, with a significant scatter due to turbulent mixing and self-shielding of H2 and CO. The H2 probability distribution function (PDF) is well-described by a log-normal distribution. In contrast, the CO column density PDF has a strongly non-Gaussian low-density wing, not at all consistent with a log-normal distribution. Centroid velocity statistics show that CO is more intermittent than H2, leading to an overestimate of the velocity scaling exponent in the velocity dispersion--size relation. With our systematic comparison of H2 and CO data from the numerical models, we hope to provide a statistical formula to correct for the bias of CO observations. CF acknowledges financial support from a Kade Fellowship of the American Museum of Natural History.

  2. The interstellar chemistry of H2C3O isomers

    PubMed Central

    Loison, Jean-Christophe; Agúndez, Marcelino; Marcelino, Núria; Wakelam, Valentine; Hickson, Kevin M.; Cernicharo, José; Gerin, Maryvonne; Roueff, Evelyne; Guélin, Michel

    2016-01-01

    We present the detection of two H2C3O isomers, propynal and cyclopropenone, toward various starless cores and molecular clouds, together with upper limits for the third isomer propadienone. We review the processes controlling the abundances of H2C3O isomers in interstellar media showing that the reactions involved are gas-phase ones. We show that the abundances of these species are controlled by kinetic rather than thermodynamic effects. PMID:27013768

  3. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    .... No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets...

  4. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    .... No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets...

  5. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    .... No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets...

  6. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets the specifications of the...

  7. Cross sections for production of H(2p, 2s, 1s) by electron collisional dissociation of H2

    NASA Technical Reports Server (NTRS)

    Ajello, J. M.; James, G. K.; Shemansky, D. E.

    1991-01-01

    The excitation function of H Ly-alpha from the astrophysically important dissociation of electron-excited H2 over the range 10-700 eV has been measured. The analysis predicts the cross section to energies higher than the present experimental limit, and it is found that the predicted shape is in close agreement with measured results. At 6 eV the cross section is dominated by the electric dipole first Born component, while at 100 eV the electric dipole component constitutes 73 percent of the total H(2p) cross section. The cross sections of the H(2s) and H(1s) components are calculated.

  8. The effect of salts on the stability of the H2A-H2B histone dimer.

    PubMed

    Gloss, Lisa M; Placek, Brandon J

    2002-12-17

    The core nucleosome, which comprises an H3-H4 tetramer and two H2A-H2B dimers, is not a static DNA packaging structure. The nucleosome is a dynamic protein-DNA complex, and the modulation of its structure is an important component of transcriptional regulation. To begin to understand the molecular details of nucleosome dynamics, we have investigated the stability of the isolated H2A-H2B dimer. The urea-induced equilibrium responses of the heterodimer have been examined by far-UV circular dichroism and intrinsic tyrosine fluorescence. The two spectroscopic probes yielded coincident transitions, and global fitting of the reversible urea-induced unfolding further demonstrated that H2A-H2B unfolds by a two-state equilibrium response. At physiological ionic strengths, the free energy of unfolding in the absence of urea of H2A-H2B is 11.8 +/- 0.3 kcal mol(-)(1), moderate stability for a dimer of 26.4 kDa. The m value, or sensitivity of the unfolding to urea, is 2.9 +/- 0.1 kcal mol(-)(1) M(-)(1). This value is significantly larger than would be predicted for the unfolding of the dimerization motif alone ( approximately 2 kcal mol(-)(1) M(-)(1)), suggesting that the N-terminal tails may adopt a collapsed, solvent-excluding structure that undergoes an unfolding transition. The efficacies of several potassium salts and three chloride salts to stabilize the H2A-H2B dimer were determined. The salt-dependent stabilization of the H2A-H2B dimer shows that the Hofmeister effect is the predominant mode of stabilization. However, studies employing multiple salts suggest that there is a component of stabilization that must arise from screening of electrostatic repulsion in the highly basic heterodimer. The most highly charged regions of the dimer are the N-terminal tails, sites of posttranslational modifications such as acetylation and phosphorylation. These modifications, which alter the charge density of the tails, are involved in regulation of nucleosome dynamics.

  9. Pallidol hexa­acetate ethyl acetate monosolvate

    PubMed Central

    Mao, Qinyong; Taylor, Dennis K.; Ng, Seik Weng; Tiekink, Edward R. T.

    2013-01-01

    The entire mol­ecule of pallidol hexa­acetate {systematic name: (±)-(4bR,5R,9bR,10R)-5,10-bis­[4-(acet­yloxy)phen­yl]-4b,5,9b,10-tetra­hydro­indeno­[2,1-a]indene-1,3,6,8-tetrayl tetra­acetate} is completed by the application of twofold rotational symmetry in the title ethyl acetate solvate, C40H34O12·C4H8O2. The ethyl acetate mol­ecule was highly disordered and was treated with the SQUEEZE routine [Spek (2009 ▶). Acta Cryst. D65, 148–155]; the crystallographic data take into account the presence of the solvent. In pallidol hexa­acetate, the dihedral angle between the fused five-membered rings (r.m.s. deviation = 0.100 Å) is 54.73 (6)°, indicating a significant fold in the mol­ecule. Significant twists between residues are also evident as seen in the dihedral angle of 80.70 (5)° between the five-membered ring and the pendent benzene ring to which it is attached. Similarly, the acetate residues are twisted with respect to the benzene ring to which they are attached [C—O(carb­oxy)—C—C torsion angles = −70.24 (14), −114.43 (10) and −72.54 (13)°]. In the crystal, a three-dimensional architecture is sustained by C—H⋯O inter­actions which encompass channels in which the disordered ethyl acetate mol­ecules reside. PMID:24046702

  10. Drug resistance marker-aided genome shuffling to improve acetic acid tolerance in Saccharomyces cerevisiae.

    PubMed

    Zheng, Dao-Qiong; Wu, Xue-Chang; Wang, Pin-Mei; Chi, Xiao-Qin; Tao, Xiang-Lin; Li, Ping; Jiang, Xin-Hang; Zhao, Yu-Hua

    2011-03-01

    Acetic acid existing in a culture medium is one of the most limiting constraints in yeast growth and viability during ethanol fermentation. To improve acetic acid tolerance in Saccharomyces cerevisiae strains, a drug resistance marker-aided genome shuffling approach with higher screen efficiency of shuffled mutants was developed in this work. Through two rounds of genome shuffling of ultraviolet mutants derived from the original strain 308, we obtained a shuffled strain YZ2, which shows significantly faster growth and higher cell viability under acetic acid stress. Ethanol production of YZ2 (within 60 h) was 21.6% higher than that of 308 when 0.5% (v/v) acetic acid was added to fermentation medium. Membrane integrity, higher in vivo activity of the H+-ATPase, and lower oxidative damage after acetic acid treatment are the possible reasons for the acetic acid-tolerance phenotype of YZ2. These results indicated that this novel genome shuffling approach is powerful to rapidly improve the complex traits of industrial yeast strains.

  11. H2 Fluorescence in M dwarf Systems: A Stellar Origin

    NASA Astrophysics Data System (ADS)

    Kruczek, Nicholas; France, Kevin; Evonosky, William; Youngblood, Allison; Parke Loyd, R. O.

    2017-01-01

    Observations of Lyα-driven H2 fluorescence can be a useful tool for measuring the abundance of H2 in exoplanet atmospheres. This emission has been previously observed in M dwarfs with planetary systems but at too low of a signal to determine its origin. It may have been originating in the atmospheres of planets, but conditions within these systems also mean that the H2 could be residing on the stellar surface or in a circumstellar disk. We use observations from the ``Measurements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanet Host Stars" (MUSCLES) Hubble Space Telescope (HST) Treasury Survey to study H2 fluorescence in M dwarfs with and without confirmed planets to determine the origin of the emission. The results are further supported by the direct imaging of a candidate M dwarf system using the HST-Advanced Camera for Surveys/Solar Blind Channel. We constrain the location of the fluorescing H2 through analysis of the line profiles and determine that the emission is originating on the star. We verify that this interpretation is consistent with 1D radiative transfer models that are optimized using the spectra of the MUSCLES stars and find that the H2 likely resides in starspots or a cool region of the lower chromosphere.

  12. H2S mediated thermal and photochemical methane activation

    PubMed Central

    Baltrusaitis, Jonas; de Graaf, Coen; Broer, Ria; Patterson, Eric

    2013-01-01

    Sustainable, low temperature methods of natural gas activation are critical in addressing current and foreseeable energy and hydrocarbon feedstock needs. Large portions of natural gas resources are still too expensive to process due to their high content of hydrogen sulfide gas (H2S) in mixture with methane, CH4, altogether deemed as sub-quality or “sour” gas. We propose a unique method for activating this “sour” gas to form a mixture of sulfur-containing hydrocarbon intermediates, CH3SH and CH3SCH3, and an energy carrier, such as H2. For this purpose, we computationally investigated H2S mediated methane activation to form a reactive CH3SH species via direct photolysis of sub-quality natural gas. Photoexcitation of hydrogen sulfide in the CH4+H2S complex results in a barrier-less relaxation via a conical intersection to form a ground state CH3SH+H2 complex. The resulting CH3SH can further be heterogeneously coupled over acidic catalysts to form higher hydrocarbons while the H2 can be used as a fuel. This process is very different from a conventional thermal or radical-based processes and can be driven photolytically at low temperatures, with enhanced controllability over the process conditions currently used in industrial oxidative natural gas activation. Finally, the proposed process is CO2 neutral, as opposed to the currently industrially used methane steam reforming (SMR). PMID:24150813

  13. H2S-mediated thermal and photochemical methane activation.

    PubMed

    Baltrusaitis, Jonas; de Graaf, Coen; Broer, Ria; Patterson, Eric V

    2013-12-02

    Sustainable, low-temperature methods for natural gas activation are critical in addressing current and foreseeable energy and hydrocarbon feedstock needs. Large portions of natural gas resources are still too expensive to process due to their high content of hydrogen sulfide gas (H2S) mixed with methane, deemed altogether as sub-quality or "sour" gas. We propose a unique method of activation to form a mixture of sulfur-containing hydrocarbon intermediates, CH3SH and CH3SCH3 , and an energy carrier such as H2. For this purpose, we investigated the H2S-mediated methane activation to form a reactive CH3SH species by means of direct photolysis of sub-quality natural gas. Photoexcitation of hydrogen sulfide in the CH4 + H2S complex resulted in a barrierless relaxation by a conical intersection to form a ground-state CH3SH + H2 complex. The resulting CH3SH could further be coupled over acidic catalysts to form higher hydrocarbons, and the resulting H2 used as a fuel. This process is very different from conventional thermal or radical-based processes and can be driven photolytically at low temperatures, with enhanced control over the conditions currently used in industrial oxidative natural gas activation. Finally, the proposed process is CO2 neutral, as opposed to the current industrial steam methane reforming (SMR).

  14. Acetate oxidation by syntrophic association between Geobacter sulfurreducens and a hydrogen-utilizing exoelectrogen.

    PubMed

    Kimura, Zen-ichiro; Okabe, Satoshi

    2013-08-01

    Anodic microbial communities in acetate-fed microbial fuel cells (MFCs) were analyzed using stable-isotope probing of 16S rRNA genes followed by denaturing gradient gel electrophoresis. The results revealed that Geobacter sulfurreducens and Hydrogenophaga sp. predominated in the anodic biofilm. Although the predominance of Geobacter sp. as acetoclastic exoelectrogens in acetate-fed MFC systems has been often reported, the ecophysiological role of Hydrogenophaga sp. is unknown. Therefore, we isolated and characterized a bacterium closely related to Hydrogenophaga sp. (designated strain AR20). The newly isolated strain AR20 could use molecular hydrogen (H2), but not acetate, with carbon electrode as the electron acceptor, indicating that the strain AR20 was a hydrogenotrophic exoelectrogen. This evidence raises a hypothesis that acetate was oxidized by G. sulfurreducens in syntrophic cooperation with the strain AR20 as a hydrogen-consuming partner in the acetate-fed MFC. To prove this hypothesis, G. sulfurreducens strain PCA was cocultivated with the strain AR20 in the acetate-fed MFC without any dissolved electron acceptors. In the coculture MFC of G. sulfurreducens and strain AR20, current generation and acetate degradation were the highest, and the growth of strain AR20 was observed. No current generation, acetate degradation and cell growth occurred in the strain AR20 pure culture MFC. These results show for the first time that G. sulfurreducens can oxidize acetate in syntrophic cooperation with the isolated Hydrogenophaga sp. strain AR20, with electrode as the electron acceptor.

  15. Biological production of ethanol from coal. [Quarterly report], March 22, 1990--June 21, 1990

    SciTech Connect

    Not Available

    1990-12-31

    The fermentation pH has been observed to be the key parameter affecting the ratio of ethanol to acetate produced by Clostridium ljungdahlii. The effects of controlled pH on cell growth and product formation by C. ljungdahlii were measured. It was found that cell concentration and acetate concentration increased with pH, while the ethanol concentration was highest at the lower pH. The molar product ratio of ethanol to acetate was 0.74 at pH 4.0, 0.39 at pH 4.5 and 0.12 at pH 5.0. Future experiments will concentrate on studying other important parameters such as agitation rate and nutrients concentrations with controlled pH as a preclude to continuous reactor studies.

  16. Acetic acid bacteria spoilage of bottled red wine -- a review.

    PubMed

    Bartowsky, Eveline J; Henschke, Paul A

    2008-06-30

    Acetic acid bacteria (AAB) are ubiquitous organisms that are well adapted to sugar and ethanol rich environments. This family of Gram-positive bacteria are well known for their ability to produce acetic acid, the main constituent in vinegar. The oxidation of ethanol through acetaldehyde to acetic acid is well understood and characterised. AAB form part of the complex natural microbial flora of grapes and wine, however their presence is less desirable than the lactic acid bacteria and yeast. Even though AAB were described by Pasteur in the 1850s, wine associated AAB are still difficult to cultivate on artificial laboratory media and until more recently, their taxonomy has not been well characterised. Wine is at most risk of spoilage during production and the presence of these strictly aerobic bacteria in grape must and during wine maturation can be controlled by eliminating, or at least limiting oxygen, an essential growth factor. However, a new risk, spoilage of wine by AAB after packaging, has only recently been reported. As wine is not always sterile filtered prior to bottling, especially red wine, it often has a small resident bacterial population (<10(3) cfu/mL), which under conducive conditions might proliferate. Bottled red wines, sealed with natural cork closures, and stored in a vertical upright position may develop spoilage by acetic acid bacteria. This spoilage is evident as a distinct deposit of bacterial biofilm in the neck of the bottle at the interface of the wine and the headspace of air, and is accompanied with vinegar, sherry, bruised apple, nutty, and solvent like off-aromas, depending on the degree of spoilage. This review focuses on the wine associated AAB species, the aroma and flavour changes in wine due to AAB metabolism, discusses the importance of oxygen ingress into the bottle and presents a hypothesis for the mechanism of spoilage of bottled red wine.

  17. H2S and volatile fatty acids elimination by biofiltration: clean-up process for biogas potential use.

    PubMed

    Ramírez-Sáenz, D; Zarate-Segura, P B; Guerrero-Barajas, C; García-Peña, E I

    2009-04-30

    In the present work, the main objective was to evaluate a biofiltration system for removing hydrogen sulfide (H(2)S) and volatile fatty acids (VFAs) contained in a gaseous stream from an anaerobic digestor (AD). The elimination of these compounds allowed the potential use of biogas while maintaining the methane (CH(4)) content throughout the process. The biodegradation of H(2)S was determined in the lava rock biofilter under two different empty bed residence times (EBRT). Inlet loadings lower than 200 g/m(3)h at an EBRT of 81 s yielded a complete removal, attaining an elimination capacity (EC) of 142 g/m(3)h, whereas at an EBRT of 31 s, a critical EC of 200 g/m(3)h was reached and the EC obtained exhibited a maximum value of 232 g/m(3)h. For 1500 ppmv of H(2)S, 99% removal was maintained during 90 days and complete biodegradation of VFAs was observed. A recovery of 60% as sulfate was obtained due to the constant excess of O(2) concentration in the system. Acetic and propionic acids as a sole source of carbon were also evaluated in the bioreactor at different inlet loadings (0-120 g/m(3)h) obtaining a complete removal (99%) for both. Microcosms biodegradation experiments conducted with VFAs demonstrated that acetic acid provided the highest biodegradation rate.

  18. Observation of enhanced rate coefficients in the H2 + + H 2 → H3 + + H reaction at low collision energies

    NASA Astrophysics Data System (ADS)

    Allmendinger, Pitt; Deiglmayr, Johannes; Höveler, Katharina; Schullian, Otto; Merkt, Frédéric

    2016-12-01

    The energy dependence of the rate coefficient of the H2 + + H 2 → H3 + + H reaction has been measured in the range of collision energies between k B ṡ 10 K and k B ṡ 300 mK . A clear deviation of the rate coefficient from the value expected on the basis of the classical Langevin-capture behavior has been observed at collision energies below k B ṡ 1 K , which is attributed to the joint effects of the ion-quadrupole and Coriolis interactions in collisions involving ortho-H2 molecules in the j = 1 rotational level, which make up 75% of the population of the neutral H2 molecules in the experiments. The experimental results are compared to very recent predictions by Dashevskaya et al. [J. Chem. Phys. 145, 244315 (2016)], with which they are in agreement.

  19. Biological production of ethanol from coal

    SciTech Connect

    Not Available

    1990-01-01

    Previous results have shown that the yeast extract concentration and the medium pH significantly affect the ratio of ethanol to acetate in the product stream when fermenting CO, CO{sub 2} and H{sub 2} in synthesis gas to products by Clostridium ljungdahlii. Further experimentation has demonstrated the impact of eliminating yeast extract from the medium (except for the slight quantity transferred with the inoculm), especially when coupled with low pH. An ethanol to acetate product ratio of 4.0 was obtained at pH 4.5 without yeast extract present in the medium when using culture previously exposed to growth-limiting H{sub 2}S. The product ratio was 2.0 at pH 4.0 (nearly three times the value of pH 4.5 and nine times the value of pH 5.0) without yeast extract present in the media when using the standard (unexposed) culture.

  20. Destruction and Sequestration of H2O on Mars

    NASA Astrophysics Data System (ADS)

    Clark, Benton

    2016-07-01

    The availability of water in biologically useable form on any planet is a quintessential resource, even if the planet is in a zone habitable with temperature regimes required for growth of organisms (above -18 °C). Mars and most other planetary objects in the solar system do not have sufficient liquid water at their surfaces that photosynthesis or chemolithoautotrophic metabolism could occur. Given clear evidence of hydrous mineral alteration and geomorphological constructs requiring abundant supplies of liquid water in the past, the question arises whether this H2O only became trapped physically as ice, or whether there could be other, more or less accessible reservoirs that it has evolved into. Salts containing S or Cl appear to be ubiquitous on Mars, having been measured in soils by all six Mars landed missions, and detected in additional areas by orbital investigations. Volcanoes emit gaseous H2S, S, SO2, HCl and Cl2. A variety of evidence indicates the geochemical fate of these gases is to be transformed into sulfates, chlorides, chlorates and perchlorates. Depending on the gas, the net reaction causes the destruction of between one and up to eight molecules of H2O per atom of S or Cl (although hydrogen atoms are also released, they are lost relatively rapidly to atmospheric escape). Furthermore, the salt minerals formed often incorporate H2O into their crystalline structures, and can result in the sequestration of up to yet another six (sometimes, more) molecules of H2O. In addition, if the salts are microcrystalline or amorphous, they are potent adsorbents for H2O. In certain cases, they are even deliquescent under martian conditions. Finally, the high solubility of the vast majority of these salts (with notable exception of CaSO4) can result in dense brines with low water activity, aH, as well as cations which can be inimical to microbial metabolism, effectively "poisoning the well." The original geologic materials on Mars, igneous rocks, also provide some

  1. Mutants of the pentose-fermenting yeast Pachysolen tannophilus tolerant to hardwood spent sulfite liquor and acetic acid.

    PubMed

    Harner, Nicole K; Bajwa, Paramjit K; Habash, Marc B; Trevors, Jack T; Austin, Glen D; Lee, Hung

    2014-01-01

    A strain development program was initiated to improve the tolerance of the pentose-fermenting yeast Pachysolen tannophilus to inhibitors in lignocellulosic hydrolysates. Several rounds of UV mutagenesis followed by screening were used to select for mutants of P. tannophilus NRRL Y2460 with improved tolerance to hardwood spent sulfite liquor (HW SSL) and acetic acid in separate selection lines. The wild type (WT) strain grew in 50 % (v/v) HW SSL while third round HW SSL mutants (designated UHW301, UHW302 and UHW303) grew in 60 % (v/v) HW SSL, with two of these isolates (UHW302 and UHW303) being viable and growing, respectively, in 70 % (v/v) HW SSL. In defined liquid media containing acetic acid, the WT strain grew in 0.70 % (w/v) acetic acid, while third round acetic acid mutants (designated UAA301, UAA302 and UAA303) grew in 0.80 % (w/v) acetic acid, with one isolate (UAA302) growing in 0.90 % (w/v) acetic acid. Cross-tolerance of HW SSL-tolerant mutants to acetic acid and vice versa was observed with UHW303 able to grow in 0.90 % (w/v) acetic acid and UAA302 growing in 60 % (v/v) HW SSL. The UV-induced mutants retained the ability to ferment glucose and xylose to ethanol in defined media. These mutants of P. tannophilus are of considerable interest for bioconversion of the sugars in lignocellulosic hydrolysates to ethanol.

  2. Change in the plasmid copy number in acetic acid bacteria in response to growth phase and acetic acid concentration.

    PubMed

    Akasaka, Naoki; Astuti, Wiwik; Ishii, Yuri; Hidese, Ryota; Sakoda, Hisao; Fujiwara, Shinsuke

    2015-06-01

    Plasmids pGE1 (2.5 kb), pGE2 (7.2 kb), and pGE3 (5.5 kb) were isolated from Gluconacetobacter europaeus KGMA0119, and sequence analyses revealed they harbored 3, 8, and 4 genes, respectively. Plasmid copy numbers (PCNs) were determined by real-time quantitative PCR at different stages of bacterial growth. When KGMA0119 was cultured in medium containing 0.4% ethanol and 0.5% acetic acid, PCN of pGE1 increased from 7 copies/genome in the logarithmic phase to a maximum of 12 copies/genome at the beginning of the stationary phase, before decreasing to 4 copies/genome in the late stationary phase. PCNs for pGE2 and pGE3 were maintained at 1-3 copies/genome during all phases of growth. Under a higher concentration of ethanol (3.2%) the PCN for pGE1 was slightly lower in all the growth stages, and those of pGE2 and pGE3 were unchanged. In the presence of 1.0% acetic acid, PCNs were higher for pGE1 (10 copies/genome) and pGE3 (6 copies/genome) during the logarithmic phase. Numbers for pGE2 did not change, indicating that pGE1 and pGE3 increase their PCNs in response to acetic acid. Plasmids pBE2 and pBE3 were constructed by ligating linearized pGE2 and pGE3 into pBR322. Both plasmids were replicable in Escherichia coli, Acetobacter pasteurianus and G. europaeus, highlighting their suitability as vectors for acetic acid bacteria.

  3. Metagenomic Evidence for H2 Oxidation and H2 Production by Serpentinite-Hosted Subsurface Microbial Communities

    PubMed Central

    Brazelton, William J.; Nelson, Bridget; Schrenk, Matthew O.

    2012-01-01

    Ultramafic rocks in the Earth’s mantle represent a tremendous reservoir of carbon and reducing power. Upon tectonic uplift and exposure to fluid flow, serpentinization of these materials generates copious energy, sustains abiogenic synthesis of organic molecules, and releases hydrogen gas (H2). In order to assess the potential for microbial H2 utilization fueled by serpentinization, we conducted metagenomic surveys of a marine serpentinite-hosted hydrothermal chimney (at the Lost City hydrothermal field) and two continental serpentinite-hosted alkaline seeps (at the Tablelands Ophiolite, Newfoundland). Novel [NiFe]-hydrogenase sequences were identified at both the marine and continental sites, and in both cases, phylogenetic analyses indicated aerobic, potentially autotrophic Betaproteobacteria belonging to order Burkholderiales as the most likely H2-oxidizers. Both sites also yielded metagenomic evidence for microbial H2 production catalyzed by [FeFe]-hydrogenases in anaerobic Gram-positive bacteria belonging to order Clostridiales. In addition, we present metagenomic evidence at both sites for aerobic carbon monoxide utilization and anaerobic carbon fixation via the Wood–Ljungdahl pathway. In general, our results point to H2-oxidizing Betaproteobacteria thriving in shallow, oxic–anoxic transition zones and the anaerobic Clostridia thriving in anoxic, deep subsurface habitats. These data demonstrate the feasibility of metagenomic investigations into novel subsurface habitats via surface-exposed seeps and indicate the potential for H2-powered primary production in serpentinite-hosted subsurface habitats. PMID:22232619

  4. Na(H2O)[Mn(H2O)2(BP2O8)]: Crystal structure refinement

    NASA Astrophysics Data System (ADS)

    Yakubovich, O. V.; Steele, I.; Dimitrova, O. V.

    2009-01-01

    The crystal structure of synthetic manganese sodium borophosphate hydrate Na(H2O)[Mn(H2O)2(BP2O8)] was refined based on X-ray diffraction data. The compound was prepared by soft hydrothermal synthesis in the MnCl2-Na3PO4-B2O3-H2O system. The unit-cell parameters are a= 9.602(1) Å, c= 16.037(3) Å, sp. gr. P6522, Z= 6, D x = 2.57 g/cm3. The water molecules were found to be statistically distributed in the channels of the mixed anionic paraframework consisting of (BO4) and (PO4) tetrahedra and [MnO4(H2O)2] octahedra. The hydrogen atoms of the water molecules coordinated to the Mn2+ cations were located and their positional and thermal parameters were refined. The crystal-chemical features of borophosphates of the general formula A x M(H2O)2(BP2O8)(H2O) are considered.

  5. Quantum dynamics of rovibrational transitions in H2-H2 collisions: internal energy and rotational angular momentum conservation effects.

    PubMed

    Fonseca dos Santos, S; Balakrishnan, N; Lepp, S; Quéméner, G; Forrey, R C; Hinde, R J; Stancil, P C

    2011-06-07

    We present a full dimensional quantum mechanical treatment of collisions between two H(2) molecules over a wide range of energies. Elastic and state-to-state inelastic cross sections for ortho-H(2) + para-H(2) and ortho-H(2) + ortho-H(2) collisions have been computed for different initial rovibrational levels of the molecules. For rovibrationally excited molecules, it has been found that state-to-state transitions are highly specific. Inelastic collisions that conserve the total rotational angular momentum of the diatoms and that involve small changes in the internal energy are found to be highly efficient. The effectiveness of these quasiresonant processes increases with decreasing collision energy and they become highly state-selective at ultracold temperatures. They are found to be more dominant for rotational energy exchange than for vibrational transitions. For non-reactive collisions between ortho- and para-H(2) molecules for which rotational energy exchange is forbidden, the quasiresonant mechanism involves a purely vibrational energy transfer albeit with less efficiency. When inelastic collisions are dominated by a quasiresonant transition calculations using a reduced basis set involving only the quasiresonant channels yield nearly identical results as the full basis set calculation leading to dramatic savings in computational cost.

  6. Photosynthetic biomass and H2 production by green algae: from bioengineering to bioreactor scale-up.

    PubMed

    Hankamer, Ben; Lehr, Florian; Rupprecht, Jens; Mussgnug, Jan H; Posten, Clemens; Kruse, Olaf

    2007-09-01

    The development of clean borderless fuels is of vital importance to human and environmental health and global prosperity. Currently, fuels make up approximately 67% of the global energy market (total market = 15 TW year(-1)) (Hoffert et al. 1998). In contrast, global electricity demand accounts for only 33% (Hoffert et al. 1998). Yet, despite the importance of fuels, almost all CO(2) free energy production systems under development are designed to drive electricity generation (e.g. clean-coal technology, nuclear, photovoltaic, wind, geothermal, wave and hydroelectric). In contrast, and indeed almost uniquely, biofuels also target the much larger fuel market and so in the future will play an increasingly important role in maintaining energy security (Lal 2005). Currently, the main biofuels that are at varying stages of development include bio-ethanol, liquid carbohydrates [e.g. biodiesel or biomass to liquid (BTL) products], biomethane and bio-H(2). This review is focused on placing bio-H(2) production processes into the context of the current biofuels market and summarizing advances made both at the level of bioengineering and bioreactor design.

  7. Calculation of intermolecular potentials for H2sbnd H2 and H2sbnd O2 dimers ab initio and prediction of second virial coefficients

    NASA Astrophysics Data System (ADS)

    Pham Van, Tat; Deiters, Ulrich K.

    2015-08-01

    The intermolecular interaction potentials of the dimers H2sbnd H2 and H2sbnd O2 were calculated from quantum mechanics, using coupled-cluster theory CCSD(T) and correlation-consistent basis sets aug-cc-pVmZ (m = 2, 3); the results were extrapolated to the basis set limit aug-cc-pV23Z. The interaction energies were corrected for the basis set superposition error with the counterpoise scheme. For comparison also Møller-Plesset perturbation theory (at levels 2-4) with the basis sets aug-cc-pVTZ were considered, but the results proved inferior. The quantum mechanical results were used to construct analytical pair potential functions. From these functions the second virial coefficients of hydrogen and the cross virial coefficients of the hydrogen-oxygen system were obtained by integration; in both cases corrections for quantum effects were included. The results agree well with experimental data, if available, or with empirical correlations.

  8. Corrosion of 310 stainless steel in H2-H2O-H2S gas mixtures: Studies at constant temperature and fixed oxygen potential

    NASA Technical Reports Server (NTRS)

    Rao, D. B.; Jacob, K. T.; Nelson, H. G.

    1981-01-01

    Corrosion of SAE 310 stainless steel in H2-H2O-H2S gas mixtures was studied at a constant temperature of 1150 K. Reactive gas mixtures were chosen to yield a constant oxygen potential of approximately 6 x 10 to the minus 13th power/cu Nm and sulfur potentials ranging from 0.19 x 10 to the minus 2nd power/cu Nm to 33 x 10 to the minus 2nd power/cu Nm. The kinetics of corrosion were determined using a thermobalance, and the scales were analyzed using metallography, scanning electron microscopy, and energy dispersive X-ray analysis. Two corrosion regimes, which were dependent on sulfur potential, were identified. At high sulfur potentials (p sub S sub 2 less than or equal to 2.7 x 10 to the minus 2nd power/cu Nm) the corrosion rates were high, the kinetics obeyed a linear rate equation, and the scales consisted mainly of sulfide phases similar to those observed from pure sulfication. At low sulfur potentials (P sub S sub 2 less than or equal to 0.19 x 10 to the minus 2nd power/cu Nm) the corrosion rates were low, the kinetics obeyed a parabolic rate equation, and scales consisted mainly of oxide phases.

  9. Uptake and Dissolution of Gaseous Ethanol in Sulfuric Acid

    NASA Technical Reports Server (NTRS)

    Michelsen, Rebecca R.; Staton, Sarah J. R.; Iraci, Laura T.

    2006-01-01

    The solubility of gas-phase ethanol (ethyl alcohol, CH3CH2OH, EtOH) in aqueous sulfuric acid solutions was measured in a Knudsen cell reactor over ranges of temperature (209-237 K) and acid composition (39-76 wt % H2SO4). Ethanol is very soluble under these conditions: effective Henry's law coefficients, H*, range from 4 x 10(exp 4) M/atm in the 227 K, 39 wt % acid to greater than 10(exp 7) M/atm in the 76 wt % acid. In 76 wt % sulfuric acid, ethanol solubility exceeds that which can be precisely determined using the Knudsen cell technique but falls in the range of 10(exp 7)-10(exp 10) M/atm. The equilibrium concentration of ethanol in upper tropospheric/lower stratospheric (UT/LS) sulfate particles is calculated from these measurements and compared to other small oxygenated organic compounds. Even if ethanol is a minor component in the gas phase, it may be a major constituent of the organic fraction in the particle phase. No evidence for the formation of ethyl hydrogen sulfate was found under our experimental conditions. While the protonation of ethanol does augment solubility at higher acidity, the primary reason H* increases with acidity is an increase in the solubility of molecular (i.e., neutral) ethanol.

  10. Theoretical characterization of the reaction CH3 +OH yields CH3OH yeilds products: The (1)CH2 + H2O, H2 + HCOH, and H2 + H2CO channels

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.

    1993-01-01

    The potential energy surface (PES) for the CH3OH system has been characterized for the (1)CH2 + H2O, H2 + HCOH, and H2 + H2CO product channels using complete-active-space self-consistent-field (CASSCF) gradient calculations to determine the stationary point geometries and frequencies followed by CASSCF/internally contracted configuration-interaction (CCI) calculations to refine the energetics. The (1)CH2 + H2O channel is found to have no barrier. The long range interaction is dominated by the dipole-dipole term, which orients the respective dipole moments parallel to each other but pointing in opposite directions. At shorter separations there is a dative bond structure in which a water lone pair donates into the empty a" orbital of CH2. Subsequent insertion of CH2 into an OH bond of water have barriers located at -5.2 kcal/mol and 1.7 kcal/mol, respectively, with respect to CH3 + OH. From comparison of the computed energetics of the reactants and products to known thermochemical data it is estimated that the computed PES is accurate to plus or minus 2 kcal/mol.

  11. Electrochemical, H2O2-Boosted Catalytic Oxidation System

    NASA Technical Reports Server (NTRS)

    Akse, James R.; Thompson, John O.; Schussel, Leonard J.

    2004-01-01

    An improved water-sterilizing aqueous-phase catalytic oxidation system (APCOS) is based partly on the electrochemical generation of hydrogen peroxide (H2O2). This H2O2-boosted system offers significant improvements over prior dissolved-oxygen water-sterilizing systems in the way in which it increases oxidation capabilities, supplies H2O2 when needed, reduces the total organic carbon (TOC) content of treated water to a low level, consumes less energy than prior systems do, reduces the risk of contamination, and costs less to operate. This system was developed as a variant of part of an improved waste-management subsystem of the life-support system of a spacecraft. Going beyond its original intended purpose, it offers the advantage of being able to produce H2O2 on demand for surface sterilization and/or decontamination: this is a major advantage inasmuch as the benign byproducts of this H2O2 system, unlike those of systems that utilize other chemical sterilants, place no additional burden of containment control on other spacecraft air- or water-reclamation systems.

  12. Role of Metabolic H2O2 Generation

    PubMed Central

    Sies, Helmut

    2014-01-01

    Hydrogen peroxide, the nonradical 2-electron reduction product of oxygen, is a normal aerobic metabolite occurring at about 10 nm intracellular concentration. In liver, it is produced at 50 nmol/min/g of tissue, which is about 2% of total oxygen uptake at steady state. Metabolically generated H2O2 emerged from recent research as a central hub in redox signaling and oxidative stress. Upon generation by major sources, the NADPH oxidases or Complex III of the mitochondrial respiratory chain, H2O2 is under sophisticated fine control of peroxiredoxins and glutathione peroxidases with their backup systems as well as by catalase. Of note, H2O2 is a second messenger in insulin signaling and in several growth factor-induced signaling cascades. H2O2 transport across membranes is facilitated by aquaporins, denoted as peroxiporins. Specialized protein cysteines operate as redox switches using H2O2 as thiol oxidant, making this reactive oxygen species essential for poising the set point of the redox proteome. Major processes including proliferation, differentiation, tissue repair, inflammation, circadian rhythm, and aging use this low molecular weight oxygen metabolite as signaling compound. PMID:24515117

  13. Cigarette sidestream smoke induces phosphorylated histone H2AX.

    PubMed

    Toyooka, Tatsushi; Ibuki, Yuko

    2009-05-31

    Cigarette sidestream smoke (CSS) is a widespread environmental pollutant having highly genotoxic potency. In spite of the overwhelming evidence that CSS induces a wide range of DNA damage such as oxidative base damage and DNA adducts, evidence that CSS can result in DNA double strand breaks (DSBs) is little. In this study, we showed that CSS generated phosphorylated histone H2AX (gamma-H2AX), recently considered as a sensitive marker of the generation of DSBs, in a human pulmonary epithelial cell model, A549. Treatment with CSS drastically induced discrete foci of gamma-H2AX within the nucleus in a dose-dependent manner. CSS increased intracellular oxidation, and N-acetylcysteine (NAC), an antioxidant, significantly attenuated the formation of gamma-H2AX, suggesting that reactive oxygen species produced from CSS partially contributed to the phosphorylation. The generation of gamma-H2AX is considered to be accompanied the induction of DSBs. CSS in fact induced DSBs, which was also inhibited by NAC. DSBs are the worst type of DNA damage, related to genomic instability and carcinogenesis. Our results would increase the evidence of the strong genotoxicity of passive smoking.

  14. H2, CO, and Dust Absorption through Cold Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Lacy, John H.; Sneden, Christopher; Kim, Hwihyun; Jaffe, Daniel T.

    2017-03-01

    The abundance of H2 in molecular clouds, relative to the commonly used tracer CO, has only been measured toward a few embedded stars, which may be surrounded by atypical gas. We present observations of near-infrared absorption by H2, CO, and dust toward stars behind molecular clouds, providing a representative sample of these molecules in cold molecular gas, primarily in the Taurus Molecular Cloud. We find {{{N}}}{{{H}}2}/{A}{{V}} ≈ 1.0 × 1021 cm‑2, {{{N}}}{CO}/{A}{{V}} ≈ 1.5 × 1017 cm‑2 (1.8 × 1017 including solid CO), and {{{N}}}{{{H}}2}/{{{N}}}{CO} ≈ 6000. The measured {{{N}}}{{{H}}2}/{{{N}}}{CO} ratio is consistent with that toward embedded stars in various molecular clouds, but both are less than that derived from millimeter-wave observations of CO and star counts. The difference apparently results from the higher directly measured {{{N}}}{CO}/{A}{{V}} ratio.

  15. Staphylococcal enterotoxins bind H-2Db molecules on macrophages

    NASA Technical Reports Server (NTRS)

    Beharka, A. A.; Iandolo, J. J.; Chapes, S. K.; Spooner, B. S. (Principal Investigator)

    1995-01-01

    We screened a panel of monoclonal antibodies against selected macrophage cell surface molecules for their ability to inhibit enterotoxin binding to major histocompatibility complex class II-negative C2D (H-2b) macrophages. Two monoclonal antibodies, HB36 and TIB126, that are specific for the alpha 2 domain of major histocompatibility complex class I, blocked staphylococcal enterotoxins A and B (SEA and SEB, respectively) binding to C2D macrophages in a specific and concentration-dependent manner. Inhibitory activities were haplotype-specific in that SEA and SEB binding to H-2k or H-2d macrophages was not inhibited by either monoclonal antibody. HB36, but not TIB126, inhibited enterotoxin-induced secretion of cytokines by H-2b macrophages. Lastly, passive protection of D-galactosamine-sensitized C2D mice by injection with HB36 antibody prevented SEB-induced death. Therefore, SEA and SEB binding to the alpha 2 domain of the H-2Db molecule induces biological activity and has physiological consequences.

  16. Rotational Spectroscopy of the NH3-H2 Molecular Complex

    NASA Astrophysics Data System (ADS)

    Surin, L. A.; Tarabukin, I. V.; Schlemmer, S.; Breier, A. A.; Giesen, T. F.; McCarthy, M. C.; van der Avoird, A.

    2017-03-01

    We report the first high resolution spectroscopic study of the NH3–H2 van der Waals molecular complex. Three different experimental techniques, a molecular beam Fourier transform microwave spectrometer, a millimeter-wave intracavity jet OROTRON spectrometer, and a submillimeter-wave jet spectrometer with multipass cell, were used to detect pure rotational transitions of NH3–H2 in the wide frequency range from 39 to 230 GHz. Two nuclear spin species, (o)-NH3–(o)-H2 and (p)-NH3–(o)-H2, have been assigned as carriers of the observed lines on the basis of accompanying rovibrational calculations performed using the ab initio intermolecular potential energy surface (PES) of Maret et al. The experimental spectra were compared with the theoretical bound state results, thus providing a critical test of the quality of the NH3–H2 PES, which is a key issue for reliable computations of the collisional excitation and de-excitation of ammonia in the dense interstellar medium.

  17. Dwarf Galaxy Formation with H2-regulated Star Formation

    NASA Astrophysics Data System (ADS)

    Kuhlen, Michael; Krumholz, Mark R.; Madau, Piero; Smith, Britton D.; Wise, John

    2012-04-01

    We describe cosmological galaxy formation simulations with the adaptive mesh refinement code Enzo that incorporate a star formation prescription regulated by the local abundance of molecular hydrogen. We show that this H2-regulated prescription leads to a suppression of star formation in low-mass halos (Mh <~ 1010 M ⊙) at z > 4, alleviating some of the dwarf galaxy problems faced by theoretical galaxy formation models. H2 regulation modifies the efficiency of star formation of cold gas directly, rather than indirectly reducing the cold gas content with "supernova feedback." We determine the local H2 abundance in our most refined grid cells (76 proper parsec in size at z = 4) by applying the model of Krumholz, McKee, & Tumlinson, which is based on idealized one-dimensional radiative transfer calculations of H2 formation-dissociation balance in ~100 pc atomic-molecular complexes. Our H2-regulated simulations are able to reproduce the empirical (albeit lower z) Kennicutt-Schmidt relation, including the low Σgas cutoff due to the transition from atomic to molecular phase and the metallicity dependence thereof, without the use of an explicit density threshold in our star formation prescription. We compare the evolution of the luminosity function, stellar mass density, and star formation rate density from our simulations to recent observational determinations of the same at z = 4-8 and find reasonable agreement between the two.

  18. A shock origin for interstellar H2O masers

    NASA Technical Reports Server (NTRS)

    Hollenbach, David; Elitzur, Moshe; Mckee, Christopher F.

    1993-01-01

    We present a comprehensive model for the powerful H2O masers observed in starforming regions. In this model the masers occur behind dissociative shocks propagating in dense regions. This paper focuses on high-velocity dissociative shocks in which the heat of H2 reformation on dust grains maintains a large column of 300 - 400 K gas, where the chemistry drives a considerable fraction of the oxygen not in CO to form H2O. The H2O column densities, the hydrogen densities, and the warm temperatures produced by these shocks are sufficiently high to enable powerful maser action, where the maser is excited by thermal collisions with H atoms and H2 molecules. A critical ingredient in determining the shock structure is the magnetic pressure, and the fields required by our models are in agreement with recent observations. The observed brightness temperatures are the result of coherent velocity regions which have dimensions in the shock plane that are five to 50 times the postshock thickness.

  19. Thermal Pressure in Diffuse H2 Gas Measured by Herschel [C II] Emission and FUSE UV H2 Absorption

    NASA Astrophysics Data System (ADS)

    Velusamy, T.; Langer, W. D.; Goldsmith, P. F.; Pineda, J. L.

    2017-04-01

    UV absorption studies with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite have made important observations of H2 molecular gas in Galactic interstellar translucent and diffuse clouds. Observations of the 158 μm [C ii] fine-structure line with Herschel trace the same H2 molecular gas in emission. We present [C ii] observations along 27 lines of sight (LOSs) toward target stars of which 25 have FUSE H2 UV absorption. Two stars have only HST STIS C ii λ2325 absorption data. We detect [C ii] 158 μm emission features in all but one target LOS. For three target LOSs that are close to the Galactic plane, | {\\text{}}b| < 1°, we also present position–velocity maps of [C ii] emission observed by Herschel Heterodyne Instrument in the Far Infrared (HIFI) in on-the-fly spectral-line mapping. We use the velocity-resolved [C ii] spectra observed by the HIFI instrument toward the target LOSs observed by FUSE to identify [C ii] velocity components associated with the H2 clouds. We analyze the observed velocity integrated [C ii] spectral-line intensities in terms of the densities and thermal pressures in the H2 gas using the H2 column densities and temperatures measured by the UV absorption data. We present the H2 gas densities and thermal pressures for 26 target LOSs and from the [C ii] intensities derive a mean thermal pressure in the range of ∼6100–7700 K cm‑3 in diffuse H2 clouds. We discuss the thermal pressures and densities toward 14 targets, comparing them to results obtained using the UV absorption data for two other tracers C i and CO. Our results demonstrate the richness of the far-IR [C ii] spectral data which is a valuable complement to the UV H2 absorption data for studying diffuse H2 molecular clouds. While the UV absorption is restricted to the directions of the target star, far-IR [C ii] line emission offers an opportunity to employ velocity-resolved spectral-line mapping capability to study in detail the clouds’ spatial and velocity

  20. Ethanol physiology in the warehouse-staining fungus, Baudoinia compniacensis.

    PubMed

    Ewaze, Juliet O; Summerbell, Richard C; Scott, James A

    2008-11-01

    The fungus Baudoinia compniacensis colonizes the exterior surfaces of a range of materials, such as buildings, outdoor furnishings, fences, signs, and vegetation, in regions subject to periodic exposure to low levels of ethanol vapour, such as those in the vicinity of distillery aging warehouses and commercial bakeries. Here we investigated the basis of ethanol metabolism in Baudoinia and investigate the role of ethanol in cell germination and growth. Germination of mycelia of Baudoinia was enhanced by up to roughly 1d exposure to low ethanol concentrations, optimally 10ppm when delivered in vapour form and 5mm in liquid form. However, growth was strongly inhibited following exposure to higher ethanol concentrations for shorter durations (e.g., 1.7m for 6h). We found that ethanol was catabolized into central metabolism via alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ACDH). Isocitrate dehydrogenases (IDHs) were active in cells grown on glucose, but these enzymes were not expressed when ethanol was provided as a sole or companion carbon source. The glyoxylate cycle enzymes isocitrate lyase (ICL) and malate synthase (MS) activities observed in cells grown on acetate were comparable to those reported for other microorganisms. By replenishing tricarboxylic acid (TCA) cycle intermediates, it is likely that the functionality of the glyoxylate cycle is important in the establishment of luxuriant growth of Baudoinia compniacensis on ethanol-exposed, nutrient-deprived, exposed surfaces. In other fungi, such as Saccharomyces cerevisiae, ADH II catalyses the conversion of ethanol to acetaldehyde, which then can be metabolized via the TCA cycle. ADH II is known to be strongly repressed in the presence of glucose.

  1. Reactivity of organic complexes at mineral-CO2-H2O interfaces

    NASA Astrophysics Data System (ADS)

    Miller, Q. R.; Schaef, T.; Kaszuba, J. P.; Qiu, L.; Bowden, M. E.; McGrail, B. P.

    2015-12-01

    Understanding the interactions between minerals and organics in H2O-CO2 fluids is important, as they are the two most abundant volatiles in the crust. CO2-rich fluids in natural and anthropogenic environments, such as metamorphic aureoles and carbon storage reservoirs, respectively, produce a complex geochemical setting in which CO2-rich fluids containing dissolved water and organic compounds interact with rocks and minerals. We have undertaken experimental and theoretical studies to evaluate how organics impact carbonate mineralization and to determine the partitioning behavior of organic complexes between CO2, H2O, and mineral interfaces. The first groups of experiments have clarified how the type and concentration of simple organic ligands impact the degree and type of carbonation in interfacial water films. In these experiments, salts of simple organic ligands were equilibrated with wet supercritical CO2, which was reacted with the model mineral forsterite (Mg2SiO4). The forsterite dissolution and coupled carbonate precipitation reactions were followed with time-resolved pressurized X-ray diffraction (XRD) at 50 °C and 90 bar. The extent of carbonation and the relative abundance of anhydrous magnesite (MgCO3) precipitated relative to hydrated nesquehonite (MgCO3·3H2O) was impacted by the type of organic ligand. Magnesite enhancement was observed with the trend of citrate>oxalate≈malonate>acetate>organic-free control. This indicates that the organic ligands complexed Mg2+ in the interfacial water film environment and helped alleviate kinetic barriers to magnesite formation. Additional XRD experiments with varying concentrations of citrate verified the dependence of magnesite enhancement and the degree of overall carbonation on the amount of organic present in the water film. Lastly, our ongoing work concerning the partitioning of organic and metal-organic complexes between CO2, H2O, and interfacial water films will be presented. This experimental work, which

  2. Comparison between acetate and hydrogen as electron donors and implications for the reductive dehalogenation of PCE and TCE

    NASA Astrophysics Data System (ADS)

    Lee, Il-Su; Bae, Jae-Ho; McCarty, Perry L.

    2007-10-01

    Bioremediation by reductive dehalogenation of groundwater contaminated with tetrachloroethene (PCE) or trichloroethene (TCE) is generally carried out through the addition of a fermentable electron donor such as lactate, benzoate, carbohydrates or vegetable oil. These fermentable donors are converted by fermenting organisms into acetate and hydrogen, either of which might be used by dehalogenating microorganisms. Comparisons were made between H 2 and acetate on the rate and extent of reductive dehalogenation of PCE. PCE dehalogenation with H 2 alone was complete to ethene, but with acetate alone it generally proceeded only about half as fast and only to cis-1,2-dichloroethene (cDCE). Additionally, acetate was not used as an electron donor in the presence of H 2. These findings suggest the fermentable electron donor requirement for PCE dehalogenation to ethene can be reduced up to 50% by separating PCE dehalogenation into two stages, the first of which uses acetate for the conversion of PCE to cDCE, and the second uses H 2 for the conversion of cDCE to ethene. This can be implemented with a recycle system in which the fermentable substrate is added down-gradient, where the hydrogen being produced by fermentation effects cDCE conversion into ethene. The acetate produced is recycled up-gradient to achieve PCE conversion into cDCE. With the lower electron donor usage required, potential problems of aquifer clogging, excess methane production, and high groundwater chemical oxygen demand (COD) can be greatly reduced.

  3. Changes in free and bound alcohol metabolites in the urine during ethanol oxidation.

    PubMed

    Tsukamoto, S; Kanegae, T; Uchigasaki, S; Kitazawa, M; Fujioka, T; Fujioka, S; Imamura, Y; Nagoya, T; Shimamura, M; Mieda, Y

    1993-12-01

    Free and bound ethanol, acetaldehyde, acetate, acetone and methanol in urine during alcohol oxidation were analyzed by means of a head space gas chromatography. Four healthy male volunteers drank beer for 20 min with 16 ml/kg for non-flushers (A, B) and 8 ml/kg for flushers (C, D). In the urine, the highest bound ethanol levels were between 0.5-1.1 mM for the non-flushers (NF) and 0.2-0.3 mM for the flushers (F). The urine free ethanol levels were 23-70 times as high as bound ethanol levels. The maximum free acetaldehyde in urine was 11-13 microM for the NF and 26-55 microM for the F. The urine bound acetaldehyde levels were 4-5 microM for the NF and 7-15 microM for the F. Urine acetaldehyde existed in free forms at 2.4-3.6 times as high concentrations as in bound forms during ethanol oxidation. The urine free acetate ranged between 0.3-2.0 mM. The bound acetate varied between 0.7-1.1 mM. The urine free methanol at 70-110 microM before the intake increased to 104-180 microM. The bound methanol reached to 78-126 microM from 48-97 microM before the intake. Ethanol levels in the urine were ethanol dose-dependent, whereas it was thought that free and bound acetaldehyde or acetate reflected individual metabolic abilities and not the amount of ethanol consumed.

  4. Wet in situ transesterification of microalgae using ethyl acetate as a co-solvent and reactant.

    PubMed

    Park, Jeongseok; Kim, Bora; Chang, Yong Keun; Lee, Jae W

    2017-04-01

    This study addresses wet in situ transesterification of microalgae for the production of biodiesel by introducing ethyl acetate as both reactant and co-solvent. Ethyl acetate and acid catalyst are mixed with wet microalgae in one pot and the mixture is heated for simultaneous lipid extraction and transesterification. As a single reactant and co-solvent, ethyl acetate can provide higher FAEE yield and more saccharification of carbohydrates than the case of binary ethanol and chloroform as a reactant and a co-solvent. The optimal yield was 97.8wt% at 114°C and 4.06M catalyst with 6.67mlEtOAC/g dried algae based on experimental results and response surface methodology (RSM). This wet in situ transesterification of microalgae using ethyl acetate doesn't require an additional co-solvent and it also promises more economic benefit as combining extraction and transesterification in a single process.

  5. Low LET radiolysis escape yields for reducing radicals and H2 in pressurized high temperature water

    NASA Astrophysics Data System (ADS)

    Sterniczuk, Marcin; Yakabuskie, Pamela A.; Wren, J. Clara; Jacob, Jasmine A.; Bartels, David M.

    2016-04-01

    Low Linear Energy Transfer (LET) radiolysis escape yields (G values) are reported for the sum (G(radH)+G(e-)aq) and for G(H2) in subcritical water up to 350 °C. The scavenger system 1-10 mM acetate/0.001 M hydroxide/0.00048 M N2O was used with simultaneous mass spectroscopic detection of H2 and N2 product. Temperature-dependent measurements were carried out with 2.5 MeV electrons from a van de Graaff accelerator, while room temperature calibration measurements were done with a 60Co gamma source. The concentrations and dose range were carefully chosen so that initial spur chemistry is not perturbed and the N2 product yield corresponds to those reducing radicals that escape recombination in pure water. In comparison with a recent review recommendation of Elliot and Bartels (AECL report 153-127160-450-001, 2009), the measured reducing radical yield is seven percent smaller at room temperature but in fairly good agreement above 150 °C. The H2 escape yield is in good agreement throughout the temperature range with several previous studies that used much larger radical scavenging rates. Previous analysis of earlier high temperature measurements of Gesc(radOH) is shown to be flawed, although the actual G values may be nearly correct. The methodology used in the present report greatly reduces the range of possible error and puts the high temperature escape yields for low-LET radiation on a much firmer quantitative foundation than was previously available.