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Sample records for acetate ethanol h2

  1. 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.

  2. 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

  3. 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.

  4. 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.; 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]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

  5. 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

  6. 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.

  7. 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.

  8. 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. PMID:27423547

  9. Ethanol and acetate production by Clostridium ljungdahlii and Clostridium autoethanogenum using resting cells.

    PubMed

    Cotter, Jacqueline L; Chinn, Mari S; Grunden, Amy M

    2009-04-01

    Combined gasification and fermentation technologies can potentially produce biofuels from renewable biomass. Gasification generates synthesis gas consisting primarily of CO, CO(2), H(2), N(2), with smaller amounts of CH(4), NO(x), O(2), C(2) compounds, ash and tars. Several anaerobic bacteria species can ferment bottled mixtures of pure synthesis gas constituents. However, there are challenges to maintaining culture viability of synthesis gas exposed cells. This study was designed to enhance culture stability and improve ethanol-to-acetate ratios using resting (non-growing) cells in synthesis gas fermentation. Resting cell states were induced in autotrophic Clostridium ljungdahlii cultures with minimal ethanol and acetate production due to low metabolic activity compared to growing cell production levels of 5.2 and 40.1 mM of ethanol and acetate. Clostridium autoethanogenum cultures were not induced into true resting states but did show improvement in total ethanol production (from 5.1 mM in growing cultures to 9.4 in one nitrogen-limited medium) as well as increased shifts in ethanol-to-acetate production ratios.

  10. 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.

  11. 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

  12. Low Temperature and H2 Selective Catalysts for Ethanol Steam Reforming

    SciTech Connect

    Roh, Hyun-Seog; Wang, Yong; King, David L.; Platon, Alex; Chin, Ya-Huei

    2006-04-01

    Supported Rh catalysts have been developed for selective H2 production at low temperatures. Ethanol dehydration is favorable over either acidic or basic supports such as γ-Al2O3 and MgAl2O4, while ethanol dehydrogenation is more favorable over neutral supports. A series of CeO2-ZrO2 supports with various CeO2/ZrO2 ratios were prepared by a co-precipitation method and Rh was impregnated on the as-synthesized support to achieve a strong metal to support interaction (SMSI). 2%Rh/Ce0.8Zr0.2O2 catalyst exhibited the highest H2 yield at 450oC among the various supported Rh catalysts evaluated in this study. This is mainly due to a favored reaction pathway via ethanol dehydrogenation to form the acetaldehyde intermediate, and both the strong interaction between Rh and Ce0.8Zr0.2O2 and the high oxygen storage capacity of Ce0.8Zr0.2O2 which favors oxidation of acetaldehyde decomposition products

  13. Physiologically based pharmacokinetic modeling of ethyl acetate and ethanol in rodents and humans.

    PubMed

    Crowell, S R; Smith, J N; Creim, J A; Faber, W; Teeguarden, J G

    2015-10-01

    A physiologically based pharmacokinetic (PBPK) model was developed and applied to a metabolic series approach for the ethyl series (i.e., ethyl acetate, ethanol, acetaldehyde, and acetate). This approach bases toxicity information on dosimetry analyses for metabolically linked compounds using pharmacokinetic data for each compound and toxicity data for parent or individual compounds. In vivo pharmacokinetic studies of ethyl acetate and ethanol were conducted in rats following IV and inhalation exposure. Regardless of route, ethyl acetate was rapidly converted to ethanol. Blood concentrations of ethyl acetate and ethanol following both IV bolus and infusion suggested linear kinetics across blood concentrations from 0.1 to 10 mM ethyl acetate and 0.01-0.8 mM ethanol. Metabolic parameters were optimized and evaluated based on available pharmacokinetic data. The respiratory bioavailability of ethyl acetate and ethanol were estimated from closed chamber inhalation studies and measured ventilation rates. The resulting ethyl series model successfully reproduces blood ethyl acetate and ethanol kinetics following IV administration and inhalation exposure in rats, and blood ethanol kinetics following inhalation exposure to ethanol in humans. The extrapolated human model was used to derive human equivalent concentrations for the occupational setting of 257-2120 ppm ethyl acetate and 72-517 ppm ethyl acetate for continuous exposure, corresponding to rat LOAELs of 350 and 1500 ppm.

  14. Physiologically based pharmacokinetic modeling of ethyl acetate and ethanol in rodents and humans.

    PubMed

    Crowell, S R; Smith, J N; Creim, J A; Faber, W; Teeguarden, J G

    2015-10-01

    A physiologically based pharmacokinetic (PBPK) model was developed and applied to a metabolic series approach for the ethyl series (i.e., ethyl acetate, ethanol, acetaldehyde, and acetate). This approach bases toxicity information on dosimetry analyses for metabolically linked compounds using pharmacokinetic data for each compound and toxicity data for parent or individual compounds. In vivo pharmacokinetic studies of ethyl acetate and ethanol were conducted in rats following IV and inhalation exposure. Regardless of route, ethyl acetate was rapidly converted to ethanol. Blood concentrations of ethyl acetate and ethanol following both IV bolus and infusion suggested linear kinetics across blood concentrations from 0.1 to 10 mM ethyl acetate and 0.01-0.8 mM ethanol. Metabolic parameters were optimized and evaluated based on available pharmacokinetic data. The respiratory bioavailability of ethyl acetate and ethanol were estimated from closed chamber inhalation studies and measured ventilation rates. The resulting ethyl series model successfully reproduces blood ethyl acetate and ethanol kinetics following IV administration and inhalation exposure in rats, and blood ethanol kinetics following inhalation exposure to ethanol in humans. The extrapolated human model was used to derive human equivalent concentrations for the occupational setting of 257-2120 ppm ethyl acetate and 72-517 ppm ethyl acetate for continuous exposure, corresponding to rat LOAELs of 350 and 1500 ppm. PMID:26297692

  15. Carbon isotopic composition of bacterial methane in a soil incubation experiment: Contributions of acetate and CO 2/H 2

    NASA Astrophysics Data System (ADS)

    Sugimoto, Atsuko; Wada, Eitaro

    1993-08-01

    Anaerobic incubations of paddy soil collected from Konosu, Japan, were carried out for 10 weeks to clarify the general principles that govern the variation of carbon isotopic composition of bacterial methane from freshwater areas. The concentrations and isotopic compositions of CH 4, CO 2, and acetate produced in the incubated system were measured. The δ13C value of biogenic CH 4 was highly variable ranging from -60 to -33%., corresponding to changes in its formation pathways: acetate fermentation and CO 2/H 2reduction. Acetate accumulated only during the first week. After it became depleted, acetate production completely limited CH 4 production. The δ13C value of the methyl carbon of acetate, which was accumulated with addition of inhibitor for methanogenesis, ranged from -43 to -30%.. The δ13C value of methane from acetate was estimated to be -43 to -30%., after acetate depletion. The δ13C value of CH 4 from CO 2/H 2 reduction was estimated to be -77 to -60%.. An enrichment in 13C of CO 2 localized around the site of methanogenesis was suggested. CO 2 produced in situ during methanogenesis (e.g., CO 2 from carboxyl group of acetate) was possibly utilized as well. Using the above δ13C values of two endmembers of CH 4, the change of acetate contribution for CH 4 production was calculated: less than 12% until week 1, 65 to 100% at weeks 1 to 3, 16 to 28% at weeks 3 to 5, and 35 to 40% after week 5. Variability of CH 4δ13C resulted from the difference in contribution of each biological process. Also, the δ13C value of CH 4 was a useful indicator for assessing the contribution of each process to methane production in sulfate depleted freshwater areas.

  16. Ethanol-induced activation of adenine nucleotide turnover. Evidence for a role of acetate

    SciTech Connect

    Puig, J.G.; Fox, I.H.

    1984-09-01

    Consumption of alcohol causes hyperuricemia by decreasing urate excretion and increasing its production. Our previous studies indicate that ethanol administration increases uric acid production by increasing ATP degradation to uric acid precursors. To test the hypothesis that ethanol-induced increased urate production results from acetate metabolism and enhanced adenosine triphosphate turnover, we gave intravenous sodium acetate, sodium chloride and ethanol (0.1 mmol/kg per min for 1 h) to five normal subjects. Acetate plasma levels increased from 0.04 +/- 0.01 mM (mean +/- SE) to peak values of 0.35 +/- 0.07 mM and to 0.08 +/- 0.01 mM during acetate and ethanol infusions, respectively. Urinary oxypurines increased to 223 +/- 13% and 316 +/- 44% of the base-line values during acetate and ethanol infusions, respectively. Urinary radioactivity from the adenine nucleotide pool labeled with (8-14C) adenine increased to 171 +/- 27% and to 128 +/- 8% of the base-line values after acetate and ethanol infusions. These data indicate that both ethanol and acetate increase purine nucleotide degradation by enhancing the turnover of the adenine nucleotide pool. They support the hypothesis that acetate metabolism contributes to the increased production of urate associated with ethanol intake.

  17. Acute effects of ethanol and acetate on glucose kinetics in normal subjects

    SciTech Connect

    Yki-Jaervinen, H.; Koivisto, V.A.; Ylikahri, R.; Taskinen, M.R. )

    1988-02-01

    The authors compared the effects of two ethanol doses on glucose kinetics and assessed the role of acetate as a mediator of ethanol-induced insulin resistance. Ten normal males were studied on four occasions, during which either a low or moderate ethanol, acetate, or saline dose was administered. Both ethanol doses similarly inhibited basal glucose production. The decrease in R{sub a} was matched by a comparable decrease in glucose utilization (R{sub d}), resulting in maintenance of normoglycemia. During hyperinsulinemia glucose disposal was lower in the moderate than the low-dose ethanol or saline studies. During acetate infusion, the blood acetate level was comparable with those in the ethanol studies. Acetate had no effect on glucose kinetics. In conclusion, (1) in overnight fasted subjects, ethanol does not cause hypoglycemia because its inhibitory effect on R{sub a} is counterbalanced by equal inhibition of R{sub d}; (2) basal R{sub a} and R{sub d} are maximally inhibited already by small ethanol doses, whereas inhibition of insulin-stimulated glucose disposal requires a moderate ethanol dose; and (3) acetate is not the mediator of ethanol-induced insulin resistance.

  18. Promotion effect of H2 on ethanol oxidation and NOx reduction with ethanol over Ag/Al2O3 catalyst.

    PubMed

    Yu, Yunbo; Li, Yi; Zhang, Xiuli; Deng, Hua; He, Hong; Li, Yuyang

    2015-01-01

    The catalytic partial oxidation of ethanol and selective catalytic reduction of NOx with ethanol (ethanol-SCR) over Ag/Al2O3 were studied using synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (PIMS). The intermediates were identified by PIMS and their photoionization efficiency (PIE) spectra. The results indicate that H2 promotes the partial oxidation of ethanol to acetaldehyde over Ag/Al2O3, while the simultaneously occurring processes of dehydration and dehydrogenation were inhibited. H2 addition favors the formation of ammonia during ethanol-SCR over Ag/Al2O3, the occurrence of which creates an effective pathway for NOx reduction by direct reaction with NH3. Simultaneously, the enhancement of the formation of ammonia benefits its reaction with surface enolic species, resulting in producing -NCO species again, leading to enhancement of ethanol-SCR over Ag/Al2O3 by H2. Using VUV-PIMS, the reactive vinyloxy radical was observed in the gas phase during the NOx reduction by ethanol for the first time, particularly in the presence of H2. Identification of such a reaction occurring in the gas phase may be crucial for understanding the reaction pathway of HC-SCR over Ag/Al2O3. PMID:25485626

  19. Promotion effect of H2 on ethanol oxidation and NOx reduction with ethanol over Ag/Al2O3 catalyst.

    PubMed

    Yu, Yunbo; Li, Yi; Zhang, Xiuli; Deng, Hua; He, Hong; Li, Yuyang

    2015-01-01

    The catalytic partial oxidation of ethanol and selective catalytic reduction of NOx with ethanol (ethanol-SCR) over Ag/Al2O3 were studied using synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (PIMS). The intermediates were identified by PIMS and their photoionization efficiency (PIE) spectra. The results indicate that H2 promotes the partial oxidation of ethanol to acetaldehyde over Ag/Al2O3, while the simultaneously occurring processes of dehydration and dehydrogenation were inhibited. H2 addition favors the formation of ammonia during ethanol-SCR over Ag/Al2O3, the occurrence of which creates an effective pathway for NOx reduction by direct reaction with NH3. Simultaneously, the enhancement of the formation of ammonia benefits its reaction with surface enolic species, resulting in producing -NCO species again, leading to enhancement of ethanol-SCR over Ag/Al2O3 by H2. Using VUV-PIMS, the reactive vinyloxy radical was observed in the gas phase during the NOx reduction by ethanol for the first time, particularly in the presence of H2. Identification of such a reaction occurring in the gas phase may be crucial for understanding the reaction pathway of HC-SCR over Ag/Al2O3.

  20. 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.

  1. 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

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

    PubMed

    Dai, Lei; Qin, Qing; Zhao, Xiaojing; Xu, Chaofa; Hu, Chengyi; Mo, Shiguang; Wang, Yu Olivia; Lin, Shuichao; Tang, Zichao; Zheng, Nanfeng

    2016-08-24

    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

  3. 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).

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

    SciTech Connect

    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.

  5. Neuroprotective effects of the Phellinus linteus ethyl acetate extract against H2O2-induced apoptotic cell death of SK-N-MC cells.

    PubMed

    Choi, Doo Jin; Cho, Sarang; Seo, Jeong Yeon; Lee, Hyang Burm; Park, Yong Il

    2016-01-01

    Numerous studies have suggested that neuronal cells are protected against oxidative stress-induced cell damage by antioxidants, such as polyphenolic compounds. Phellinus linteus (PL) has traditionally been used to treat various symptoms in East Asian countries. In the present study, we prepared an ethyl acetate extract from the fruiting bodies of PL (PLEA) using hot water extraction, ethanol precipitation, and ethyl acetate extraction. The PLEA contained polyphenols as its major chemical component, and thus, we predicted that it may exhibit antioxidant and neuroprotective effects against oxidative stress. The results showed that the pretreatment of human brain neuroblastoma SK-N-MC cells with the PLEA (0.1-5 μg/mL) significantly and dose-dependently reduced the cytotoxicity of H2O2 and the intracellular ROS levels and enhanced the expression of HO-1 (heme oxygenase-1) and antioxidant enzymes, such as CAT (catalase), GPx-1 (glutathione peroxidase-1), and SOD-1 and -2 (superoxide dismutase-1 and -2). The PLEA also directly scavenged free radicals. PLEA pretreatment also significantly attenuated DNA fragmentation and suppressed the mRNA expression and activation of mitogen-activated protein kinases extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 kinase, which are induced by oxidative stress and lead to cell death. PLEA pretreatment inhibited the activation of the apoptosis-related proteins caspase-3 and poly (ADP-ribose) polymerase. These results demonstrate that the PLEA has neuroprotective effects against oxidative stress (H2O2)-induced neuronal cell death via its antioxidant and anti-apoptotic properties. PLEA should be investigated in an in vivo model on its potential to prevent or ameliorate neurodegenerative disease. PMID:26773779

  6. Linking genome content to biofuel production yields: a meta-analysis of major catabolic pathways among select H2 and ethanol-producing bacteria

    PubMed Central

    2012-01-01

    Background Fermentative bacteria offer the potential to convert lignocellulosic waste-streams into biofuels such as hydrogen (H2) and ethanol. Current fermentative H2 and ethanol yields, however, are below theoretical maxima, vary greatly among organisms, and depend on the extent of metabolic pathways utilized. For fermentative H2 and/or ethanol production to become practical, biofuel yields must be increased. We performed a comparative meta-analysis of (i) reported end-product yields, and (ii) genes encoding pyruvate metabolism and end-product synthesis pathways to identify suitable biomarkers for screening a microorganism’s potential of H2 and/or ethanol production, and to identify targets for metabolic engineering to improve biofuel yields. Our interest in H2 and/or ethanol optimization restricted our meta-analysis to organisms with sequenced genomes and limited branched end-product pathways. These included members of the Firmicutes, Euryarchaeota, and Thermotogae. Results Bioinformatic analysis revealed that the absence of genes encoding acetaldehyde dehydrogenase and bifunctional acetaldehyde/alcohol dehydrogenase (AdhE) in Caldicellulosiruptor, Thermococcus, Pyrococcus, and Thermotoga species coincide with high H2 yields and low ethanol production. Organisms containing genes (or activities) for both ethanol and H2 synthesis pathways (i.e. Caldanaerobacter subterraneus subsp. tengcongensis, Ethanoligenens harbinense, and Clostridium species) had relatively uniform mixed product patterns. The absence of hydrogenases in Geobacillus and Bacillus species did not confer high ethanol production, but rather high lactate production. Only Thermoanaerobacter pseudethanolicus produced relatively high ethanol and low H2 yields. This may be attributed to the presence of genes encoding proteins that promote NADH production. Lactate dehydrogenase and pyruvate:formate lyase are not conducive for ethanol and/or H2 production. While the type(s) of encoded hydrogenases appear

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

    SciTech Connect

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

    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.

  8. 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

  9. 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.

  10. U(VI) Reduction in Sulfate-Reducing Subsurface Sediments Amended with Ethanol or Acetate

    PubMed Central

    Converse, Brandon J.; Wu, Tao; Findlay, Robert H.

    2013-01-01

    An experiment was conducted with subsurface sediments from Oak Ridge National Laboratory to determine the potential for reduction of U(VI) under sulfate-reducing conditions with either ethanol or acetate as the electron donor. The results showed extensive U(VI) reduction in sediments supplied with either electron donor, where geochemical and microbiological analyses demonstrated active sulfate reduction. PMID:23624470

  11. Genetic diversity of hydrogen-producing bacteria in an acidophilic ethanol-H2-coproducing system, analyzed using the [Fe]-hydrogenase gene.

    PubMed

    Xing, Defeng; Ren, Nanqi; Rittmann, Bruce E

    2008-02-01

    Hydrogen gas (H2) produced by bacterial fermentation of biomass can be a sustainable energy source. The ability to produce H2 gas during anaerobic fermentation was previously thought to be restricted to a few species within the genera Clostridium and Enterobacter. This work reports genomic evidence for the presence of novel H2-producing bacteria (HPB) in acidophilic ethanol-H2-coproducing communities that were enriched using molasses wastewater. The majority of the enriched dominant populations in the acidophilic ethanol-H2-coproducing system were affiliated with low-G+C-content gram-positive bacteria, Bacteroidetes, and Actinobacteria, based on the 16S rRNA gene. However, PCR primers designed to specifically target bacterial hydA yielded 17 unique hydA sequences whose amino acid sequences differed from those of known HPB. The putative ethanol-H2-coproducing bacteria comprised 11 novel phylotypes closely related to Ethanoligenens harbinense, Clostridium thermocellum, and Clostridium saccharoperbutylacetonicum. Furthermore, analysis of the alcohol dehydrogenase isoenzyme also pointed to an E. harbinense-like organism, which is known to have a high conversion rate of carbohydrate to H2 and ethanol. We also found six novel HPB that were associated with lactate-, propionate-, and butyrate-oxidizing bacteria in the acidophilic H2-producing sludge. Thus, the microbial ecology of mesophilic and acidophilic H2 fermentation involves many other bacteria in addition to Clostridium and Enterobacter.

  12. Genetic Diversity of Hydrogen-Producing Bacteria in an Acidophilic Ethanol-H2-Coproducing System, Analyzed Using the [Fe]-Hydrogenase Gene▿ †

    PubMed Central

    Xing, Defeng; Ren, Nanqi; Rittmann, Bruce E.

    2008-01-01

    Hydrogen gas (H2) produced by bacterial fermentation of biomass can be a sustainable energy source. The ability to produce H2 gas during anaerobic fermentation was previously thought to be restricted to a few species within the genera Clostridium and Enterobacter. This work reports genomic evidence for the presence of novel H2-producing bacteria (HPB) in acidophilic ethanol-H2-coproducing communities that were enriched using molasses wastewater. The majority of the enriched dominant populations in the acidophilic ethanol-H2-coproducing system were affiliated with low-G+C-content gram-positive bacteria, Bacteroidetes, and Actinobacteria, based on the 16S rRNA gene. However, PCR primers designed to specifically target bacterial hydA yielded 17 unique hydA sequences whose amino acid sequences differed from those of known HPB. The putative ethanol-H2-coproducing bacteria comprised 11 novel phylotypes closely related to Ethanoligenens harbinense, Clostridium thermocellum, and Clostridium saccharoperbutylacetonicum. Furthermore, analysis of the alcohol dehydrogenase isoenzyme also pointed to an E. harbinense-like organism, which is known to have a high conversion rate of carbohydrate to H2 and ethanol. We also found six novel HPB that were associated with lactate-, propionate-, and butyrate-oxidizing bacteria in the acidophilic H2-producing sludge. Thus, the microbial ecology of mesophilic and acidophilic H2 fermentation involves many other bacteria in addition to Clostridium and Enterobacter. PMID:18156331

  13. 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.

  14. 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. PMID:26712629

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

    PubMed

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

    1987-06-01

    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 Pestal-otiopsis westerdijkii enzymes (containing cellulolytic and acetyl esterase components) and yeast.Water-soluble cellulose acetate was successfully prepared from purified wood cellulose (Solka Floe) and chemical reagents. Enzyme pretreatment of WSCAto form metabolizable sugars was a necessary step in achieving practical conversion of WSCA to ethanol using yeast. The results showed that WSCA has a low enzyme requirement and a high convertibility to reducing sugars with enzymes from P. westerdijkii fungus. Pestalotiopsis westerdijkii enzymes were found to be superior to enzymes from Trichoderma viride in producing metabolizable glucose from WSCA. The yeast utilized 55-70% of the hydrolyzate sugars that were produced by P. westerrlijkii enzymes on WSCA and produced ethanol. The acetate that was liberated into solution by the action of acetyl esterase enzymes on WSCA was found to have a stimulatory effect on ethanol production in yeast. This is an important feature that can be used to advantage in manipulating the conversion to maximize the production of ethanol. Hence, the simultaneous saccharification-fermentation of WSCA to ethanol using P. westerdijkii enzymes and yeast has features that are highly desirable for developing an economical cellulose conversion process.

  16. 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.

  17. Ethanol metabolism in ALDH2 knockout mice--blood acetate levels.

    PubMed

    Kiyoshi, Ameno; Weihuan, Wang; Mostofa, Jamal; Mitsuru, Kumihashi; Toyoshi, Isse; Toshihiro, Kawamoto; Kyoko, Kitagawa; Keiichi, Nakayama; Iwao, Ijiri; Hiroshi, Kinoshita

    2009-04-01

    We described here blood acetate levels in aldehyde dehydrogenase 2 knockout (ALDH2 KO) male mice based on C57BL/6J strain after ethanol (EtOH) dosing (2 g/kg). Blood samples were collected at 30, 60, 90, 120 180, and 240 min after decapitation, and then EtOH, acetaldehyde (AcH) and acetate were determined by head-space gas chromatography. We found that blood acetate levels in ALDH2 KO mice were slightly lower than those in wild type (WT), whereas EtOH and AcH levels in ALDH2 KO were significantly higher than those in WT. These observations indicate that high EtOH, AcH and low acetate in the blood of ALDH2 KO are due to the deficient effect of ALDH2 enzyme activity. PMID:19356968

  18. Recovery of acetic acid from dilute aqueous solutions using catalytic dehydrative esterification with ethanol.

    PubMed

    Yagyu, Daisuke; Ohishi, Tetsuo; Igarashi, Takeshi; Okumura, Yoshikuni; Nakajo, Tetsuo; Mori, Yuichiro; Kobayashi, Shū

    2013-03-01

    We have developed a direct esterification of aqueous acetic acid with ethanol (molar ratio=1:1) catalyzed by polystyrene-supported or homogeneous sulfonic acids toward the recovery of acetic acid from wastewater in chemical plants. The equilibrium yield was significantly increased by the addition of toluene, which had a high ability to extract ethyl acetate from the aqueous phase. It was shown that low-loading and alkylated polystyrene-supported sulfonic acid efficiently accelerated the reaction. These results suggest that the construction of hydrophobic reaction environments in water was critical in improving the chemical yield. Addition of inorganic salts was also effective for the reaction under not only biphasic conditions (toluene-water) but also toluene-free conditions, because the mutual solubility of ethyl acetate and water was suppressed by the salting-out effect. Among the tested salts, CaCl(2) was found to be the most suitable for this reaction system. PMID:23290939

  19. 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.

  20. 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.

  1. 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...

  2. 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.

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

    PubMed

    Zhang, Hongdan; Wu, Shubin

    2014-12-01

    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.

  4. 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.

  5. Analytical model for BTEX natural attenuation in the presence of fuel ethanol and its anaerobic metabolite acetate.

    PubMed

    da Silva, Marcio L B; Gomez, Diego E; Alvarez, Pedro J J

    2013-03-01

    Flow-through column studies were conducted to mimic the natural attenuation of ethanol and BTEX mixtures, and to consider potential inhibitory effects of ethanol and its anaerobic metabolite acetate on BTEX biodegradation. Results were analyzed using a one-dimensional analytical model that was developed using consecutive reaction differential equations based on first-order kinetics. Decrease in pH due to acetogenesis was also modeled, using charge balance equations under CaCO(3) dissolution conditions. Delay in BTEX removal was observed and simulated in the presence of ethanol and acetate. Acetate was the major volatile fatty acid intermediate produced during anaerobic ethanol biodegradation (accounting for about 58% of the volatile fatty acid mass) as suggested by the model data fit. Acetate accumulation (up to 1.1 g/L) near the source zone contributed to a pH decrease by almost one unit. The anaerobic degradation of ethanol (2 g/L influent concentration) at the source zone produced methane at concentrations exceeding its solubility (~/=26mg/L). Overall, this simple analytical model adequately described ethanol degradation, acetate accumulation and methane production patterns, suggesting that it could be used as a screening tool to simulate lag times in BTEX biodegradation, changes in groundwater pH and methane generation following ethanol-blended fuel releases.

  6. Analytical model for BTEX natural attenuation in the presence of fuel ethanol and its anaerobic metabolite acetate

    NASA Astrophysics Data System (ADS)

    da Silva, Marcio L. B.; Gomez, Diego E.; Alvarez, Pedro J. J.

    2013-03-01

    Flow-through column studies were conducted to mimic the natural attenuation of ethanol and BTEX mixtures, and to consider potential inhibitory effects of ethanol and its anaerobic metabolite acetate on BTEX biodegradation. Results were analyzed using a one-dimensional analytical model that was developed using consecutive reaction differential equations based on first-order kinetics. Decrease in pH due to acetogenesis was also modeled, using charge balance equations under CaCO3 dissolution conditions. Delay in BTEX removal was observed and simulated in the presence of ethanol and acetate. Acetate was the major volatile fatty acid intermediate produced during anaerobic ethanol biodegradation (accounting for about 58% of the volatile fatty acid mass) as suggested by the model data fit. Acetate accumulation (up to 1.1 g/L) near the source zone contributed to a pH decrease by almost one unit. The anaerobic degradation of ethanol (2 g/L influent concentration) at the source zone produced methane at concentrations exceeding its solubility (≅ 26 mg/L). Overall, this simple analytical model adequately described ethanol degradation, acetate accumulation and methane production patterns, suggesting that it could be used as a screening tool to simulate lag times in BTEX biodegradation, changes in groundwater pH and methane generation following ethanol-blended fuel releases.

  7. 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...

  8. Electrooxidation of Ethanol and Methanol Using the Molecular Catalyst [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2](10.).

    PubMed

    Liu, YuPing; Zhao, Shu-Feng; Guo, Si-Xuan; Bond, Alan M; Zhang, Jie; Zhu, Guibo; Hill, Craig L; Geletii, Yurii V

    2016-03-01

    Highly efficient electrocatalytic oxidation of ethanol and methanol has been achieved using the ruthenium-containing polyoxometalate molecular catalyst, [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2](10-) ([1(γ-SiW10O36)2](10-)). Voltammetric studies with dissolved and surface-confined forms of [1(γ-SiW10O36)2](10-) suggest that the oxidized forms of 1 can act as active catalysts for alcohol oxidation in both aqueous (over a wide pH range covering acidic, neutral, and alkaline) and alcohol media. Under these conditions, the initial form of 1 also exhibits considerable reactivity, especially in neutral solution containing 1.0 M NaNO3. To identify the oxidation products, preparative scale bulk electrolysis experiments were undertaken. The products detected by NMR, gas chromatography (GC), and GC-mass spectrometry from oxidation of ethanol are 1,1-diethoxyethane and ethyl acetate formed from condensation of acetaldehyde or acetic acid with excess ethanol. Similarly, the oxidation of methanol generates formaldehyde and formic acid which then condense with methanol to form dimethoxymethane and methyl formate, respectively. These results demonstrate that electrocatalytic oxidation of ethanol and methanol occurs via two- and four-electron oxidation processes to yield aldehydes and acids. The total faradaic efficiencies of electrocatalytic oxidation of both alcohols exceed 94%. The numbers of aldehyde and acid products per catalyst were also calculated and compared with the literature reported values. The results suggest that 1 is one of the most active molecular electrocatalysts for methanol and ethanol oxidation.

  9. Electrooxidation of Ethanol and Methanol Using the Molecular Catalyst [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2](10.).

    PubMed

    Liu, YuPing; Zhao, Shu-Feng; Guo, Si-Xuan; Bond, Alan M; Zhang, Jie; Zhu, Guibo; Hill, Craig L; Geletii, Yurii V

    2016-03-01

    Highly efficient electrocatalytic oxidation of ethanol and methanol has been achieved using the ruthenium-containing polyoxometalate molecular catalyst, [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2](10-) ([1(γ-SiW10O36)2](10-)). Voltammetric studies with dissolved and surface-confined forms of [1(γ-SiW10O36)2](10-) suggest that the oxidized forms of 1 can act as active catalysts for alcohol oxidation in both aqueous (over a wide pH range covering acidic, neutral, and alkaline) and alcohol media. Under these conditions, the initial form of 1 also exhibits considerable reactivity, especially in neutral solution containing 1.0 M NaNO3. To identify the oxidation products, preparative scale bulk electrolysis experiments were undertaken. The products detected by NMR, gas chromatography (GC), and GC-mass spectrometry from oxidation of ethanol are 1,1-diethoxyethane and ethyl acetate formed from condensation of acetaldehyde or acetic acid with excess ethanol. Similarly, the oxidation of methanol generates formaldehyde and formic acid which then condense with methanol to form dimethoxymethane and methyl formate, respectively. These results demonstrate that electrocatalytic oxidation of ethanol and methanol occurs via two- and four-electron oxidation processes to yield aldehydes and acids. The total faradaic efficiencies of electrocatalytic oxidation of both alcohols exceed 94%. The numbers of aldehyde and acid products per catalyst were also calculated and compared with the literature reported values. The results suggest that 1 is one of the most active molecular electrocatalysts for methanol and ethanol oxidation. PMID:26848832

  10. 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.

  11. Effect of acetic acid on Saccharomyces carlsbergensis ATCC 6269 batch ethanol production monitored by flow cytometry.

    PubMed

    Freitas, Cláudia; Neves, Elisabete; Reis, Alberto; Passarinho, Paula C; da Silva, Teresa Lopes

    2012-11-01

    Bioethanol produced from lignocellulosic materials has been considered a sustainable alternative fuel. Such type of raw materials have a huge potential, but their hydrolysis into mono-sugars releases toxic compounds such as weak acids, which affect the microorganisms' physiology, inhibiting the growth and ethanol production. Acetic acid (HAc) is the most abundant weak acid in the lignocellulosic materials hydrolysates. In order to understand the physiological changes of Saccharomyces carlsbergensis when fermenting in the presence of different acetic acid (HAc) concentrations, the yeast growth was monitored by multi-parameter flow cytometry at same time that the ethanol production was assessed. The membrane potential stain DiOC(6)(3) fluorescence intensity decreased as the HAc concentration increased, which was attributed to the plasmic membrane potential reduction as a result of the toxic effect of the HAc undissociated form. Nevertheless, the proportion of cells with permeabilized membrane did not increase with the HAc concentration increase. Fermentations ending at lower external pH and higher ethanol concentrations depicted the highest proportions of permeabilized cells and cells with increased reactive oxygen species levels. Flow cytometry allowed monitoring, near real time (at-line), the physiological states of the yeast during the fermentations. The information obtained can be used to optimize culture conditions to improve bioethanol production. PMID:22971830

  12. Effect of acetic acid on Saccharomyces carlsbergensis ATCC 6269 batch ethanol production monitored by flow cytometry.

    PubMed

    Freitas, Cláudia; Neves, Elisabete; Reis, Alberto; Passarinho, Paula C; da Silva, Teresa Lopes

    2012-11-01

    Bioethanol produced from lignocellulosic materials has been considered a sustainable alternative fuel. Such type of raw materials have a huge potential, but their hydrolysis into mono-sugars releases toxic compounds such as weak acids, which affect the microorganisms' physiology, inhibiting the growth and ethanol production. Acetic acid (HAc) is the most abundant weak acid in the lignocellulosic materials hydrolysates. In order to understand the physiological changes of Saccharomyces carlsbergensis when fermenting in the presence of different acetic acid (HAc) concentrations, the yeast growth was monitored by multi-parameter flow cytometry at same time that the ethanol production was assessed. The membrane potential stain DiOC(6)(3) fluorescence intensity decreased as the HAc concentration increased, which was attributed to the plasmic membrane potential reduction as a result of the toxic effect of the HAc undissociated form. Nevertheless, the proportion of cells with permeabilized membrane did not increase with the HAc concentration increase. Fermentations ending at lower external pH and higher ethanol concentrations depicted the highest proportions of permeabilized cells and cells with increased reactive oxygen species levels. Flow cytometry allowed monitoring, near real time (at-line), the physiological states of the yeast during the fermentations. The information obtained can be used to optimize culture conditions to improve bioethanol production.

  13. The dynamics of histone H2A ubiquitination in HeLa cells exposed to rapamycin, ethanol, hydroxyurea, ER stress, heat shock and DNA damage.

    PubMed

    Nakata, Shiori; Watanabe, Tadashi; Nakagawa, Koji; Takeda, Hiroshi; Ito, Akihiro; Fujimuro, Masahiro

    2016-03-25

    Polyubiquitination plays key roles in proteasome-dependent and independent cellular events, whereas monoubiquitination is involved in gene expression, DNA repair, protein-protein interaction, and protein trafficking. We previously developed an FK2 antibody, which specifically recognizes poly-Ub moieties but not free Ub. To elucidate the role of Ub conjugation in response to cellular stress, we used FK2 to investigate whether chemical stress (rapamycin, ethanol, or hydroxyurea), ER stress (thapsigargin or tunicamycin), heat shock or DNA damage (H2O2 or methyl methanesulfonate) affect the formation of Ub conjugates including histone H2A (hH2A) ubiquitination. First, we found that all forms of stress tested increased poly-ubiquitinated proteins in HeLa cells. Furthermore, rapamycin and hydroxyurea treatment, and ER stress increased ubiquitination of hH2A, while methyl methanesulfonate (MMS) treatment induced deubiquitination of hH2A. The ethanol and H2O2 treatments, and heat shock transiently induced hH2A de-ubiquitination, although deubiquitinated hH2A were ubiquitinated again by subsequent cultivation. We also revealed that FK2 reacts with not only polyubiquitinated proteins but also mono-ubiquitinated hH2A. With the exception of MMS, all forms of stress tested increased the acetylation of K5-hH2A, K9-hH3 and K8-hH4 in addition to ubiquitination. K118 and K119 of hH2A were ubiquitinated in cells under normal conditions, and K119 was the major ubiquitination site. The MMS-treatment and heat shock induced the deubiquitination of both K118 and K119-histone H2A. Interestingly, MMS treatment did not affect cell HeLa cell viability expressing double-mutant hH2A (KK118,119AA-hH2A), while heat shock slightly but significantly decreased viability of double-mutant hH2A expressing cells, indicating that ubiquitination of both sites associates with recovery from heat shock but not MMS treatment. Thus, we characterized FK2 reactivity and demonstrated that various stresses alter

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

    PubMed

    Yaacob, Norhayati; Mohamad Ali, Mohd Shukuri; 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

  15. 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

  16. Microsolvation of the acetate anion [CH3CO-2(H2O)n,n=1-3]: A photoelectron spectroscopy and ab initio computational sutdy

    SciTech Connect

    Wang, Xue B.; Jagoda-Cwiklik, Barbra; Chi, Chaoxian; Xing, Xiaopeng; Zhou, Mingfei; Jungwirth, Pavel; Wang, Lai S.

    2009-07-28

    A combined photoelectron spectroscopy and ab initio theoretical study was carried out to study the microsolvation of the acetate anion. Photoelectron spectra of cold solvated clusters CH3CO-2 ðH2OÞn (n = 1-3) at 12 K were obtained and compared with theoretical calculations. The first water is shown to bind to the -CO -2 group in a bidentate fashion, whereas both water-water and water-CO-2 interactions are shown for n = 2 and 3. Significant rearrangement of the solvation structures is observed upon electron detachment, and water-CH3 interactions are present for all the neutral clusters, CH3CO2(H2O)n (n = 1-3).

  17. Reforming of oxygenates for H2 production: correlating reactivity of ethylene glycol and ethanol on Pt(111) and Ni/Pt(111) with surface d-band center.

    PubMed

    Skoplyak, Orest; Barteau, Mark A; Chen, Jingguang G

    2006-02-01

    The dehydrogenation and decarbonylation of ethylene glycol and ethanol were studied using temperature programmed desorption (TPD) on Pt(111) and Ni/Pt(111) bimetallic surfaces, as probe reactions for the reforming of oxygenates for the production of H2 for fuel cells. Ethylene glycol reacted via dehydrogenation to form CO and H2, corresponding to the desired reforming reaction, and via total decomposition to produce C(ad), O(ad), and H2. Ethanol reacted by three reaction pathways, dehydrogenation, decarbonylation, and total decomposition, producing CO, H2, CH4, C(ad), and O(ad). Surfaces prepared by deposition of a monolayer of Ni on Pt(111) at 300 K, designated Ni-Pt-Pt(111), displayed increased reforming activity compared to Pt(111), subsurface monolayer Pt-Ni-Pt(111), and thick Ni/Pt(111). Reforming activity was correlated with the d-band center of the surfaces and displayed a linear trend for both ethylene glycol and ethanol, with activity increasing as the surface d-band center moved closer to the Fermi level. This trend was opposite to that previously observed for hydrogenation reactions, where increased activity occurred on subsurface monolayers as the d-band center shifted away from the Fermi level. Extrapolation of the correlation between activity and the surface d-band center of bimetallic systems may provide useful predictions for the selection and rational design of bimetallic catalysts for the reforming of oxygenates. PMID:16471734

  18. Improving the environmental profile of wood panels via co-production of ethanol and acetic acid.

    PubMed

    Earles, J Mason; Halog, Anthony; Shaler, Stephen

    2011-11-15

    The oriented strand board (OSB) biorefinery is an emerging technology that could improve the building, transportation, and chemical sectors' environmental profiles. By adding a hot water extraction stage to conventional OSB panel manufacturing, hemicellulose polysaccharides can be extracted from wood strands and converted to renewably sourced ethanol and acetic acid. Replacing fossil-based gasoline and acetic acid has the potential to reduce greenhouse gas (GHG) emissions, among other possible impacts. At the same time, hemicellulose extraction could improve the environmental profile of OSB panels by reducing the level of volatile organic compounds (VOCs) emitted during manufacturing. In this study, the life cycle significance of such GHG, VOC, and other emission reductions was investigated. A process model was developed based on a mix of laboratory and industrial-level mass and energy flow data. Using these data a life cycle assessment (LCA) model was built. Sensitive process parameters were identified and used to develop a target production scenario for the OSB biorefinery. The findings suggest that the OSB biorefinery's deployment could substantially improve human and ecosystem health via reduction of select VOCs compared to conventionally produced OSB, gasoline, and acetic acid. Technological advancements are needed, however, to achieve desirable GHG reductions. PMID:21967719

  19. Experimental and DFT studies of the conversion of ethanol and acetic acid on PtSn-based catalysts.

    PubMed

    Alcala, Rafael; Shabaker, John W; Huber, George W; Sanchez-Castillo, Marco A; Dumesic, James A

    2005-02-17

    Reaction kinetics studies were conducted for the conversions of ethanol and acetic acid over silica-supported Pt and Pt/Sn catalysts at temperatures from 500 to 600 K. Addition of Sn to Pt catalysts inhibits the decomposition of ethanol to CO, CH4, and C2H6, such that PtSn-based catalysts are active for dehydrogenation of ethanol to acetaldehyde. Furthermore, PtSn-based catalysts are selective for the conversion of acetic acid to ethanol, acetaldehyde, and ethyl acetate, whereas Pt catalysts lead mainly to decomposition products such as CH4 and CO. These results are interpreted using density functional theory (DFT) calculations for various adsorbed species and transition states on Pt(111) and Pt3Sn(111) surfaces. The Pt3Sn alloy slab was selected for DFT studies because results from in situ (119)Sn Mössbauer spectroscopy and CO adsorption microcalorimetry of silica-supported Pt/Sn catalysts indicate that Pt-Sn alloy is the major phase present. Accordingly, results from DFT calculations show that transition-state energies for C-O and C-C bond cleavage in ethanol-derived species increase by 25-60 kJ/mol on Pt3Sn(111) compared to Pt(111), whereas energies of transition states for dehydrogenation reactions increase by only 5-10 kJ/mol. Results from DFT calculations show that transition-state energies for CH3CO-OH bond cleavage increase by only 12 kJ/mol on Pt3Sn(111) compared to Pt(111). The suppression of C-C bond cleavage in ethanol and acetic acid upon addition of Sn to Pt is also confirmed by microcalorimetric and infrared spectroscopic measurements at 300 K of the interactions of ethanol and acetic acid with Pt and PtSn on a silica support that had been silylated to remove silanol groups. PMID:16851198

  20. Constructing a polyfunctional zeolite-encaged metal catalyst for the multistage oxidation of ethanol into ethyl acetate

    SciTech Connect

    Shakhtakhtinskii, T.N.; Aliev, A.M.; Kuliev, A.R.

    1995-08-01

    To construct an efficient polyfunctional catalyst for the given multistage reaction, the authors previously studied the catalysts HNaY, clinosorb, H-clinoptilolite, and H-mordenite in the reaction of esterification of ethanol with acetic acid; CuH-clinoptilolite, Cu-clinosorb, CuH-mordenite, and CuHNaY in the reaction of oxidative dehydration of ethanol; PdH-clinoptilolite, Pd-clinosorb, PdH-mordenite, and PdHNaY in the oxidation of ethanol; and CuPdH-clinoptilolite in the oxidative transformation of ethanol into ethyl acetate. The catalytic activity of these zeolites and other Pd- and Cu-containing zeolite catalysts, which the authors synthesized by the ion-exchange technique, was studied in a flow-circulating set-up.

  1. Methanol and ethanol oxidase respiratory chains of the methylotrophic acetic acid bacterium, Acetobacter methanolicus.

    PubMed

    Matsushita, K; Takahashi, K; Takahashi, M; Ameyama, M; Adachi, O

    1992-06-01

    Acetobacter methanolicus is a unique acetic acid bacterium which has a methanol oxidase respiratory chain, as seen in methylotrophs, in addition to its ethanol oxidase respiratory chain. In this study, the relationship between methanol and ethanol oxidase respiratory chains was investigated. The organism is able to grow by oxidizing several carbon sources, including methanol, glycerol, and glucose. Cells grown on methanol exhibited a high methanol-oxidizing activity and contained large amounts of methanol dehydrogenase and soluble cytochromes c. Cells grown on glycerol showed higher oxygen uptake rate and dehydrogenase activity with ethanol but little methanol-oxidizing activity. Furthermore, two different terminal oxidases, cytochrome c and ubiquinol oxidases, have been shown to be involved in the respiratory chain; cytochrome c oxidase predominates in cells grown on methanol while ubiquinol oxidase predominates in cells grown on glycerol. Both terminal oxidases could be solubilized from the membranes and separated from each other. The cytochrome c oxidase and the ubiquinol oxidase have been shown to be a cytochrome co and a cytochrome bo, respectively. Methanol-oxidizing activity was diminished by several treatments that disrupt the integrity of the cells. The activity of the intact cells was inhibited with NaCl and/or EDTA, which disturbed the interaction between methanol dehydrogenase and cytochrome c. Ethanol-oxidizing activity in the membranes was inhibited with 2-heptyl-4-hydroxyquinoline N-oxide, which inhibited ubiquinol oxidase but not cytochrome c oxidase. Alcohol dehydrogenase has been purified from the membranes of glycerol-grown cells and shown to reduce ubiquinone-10 as well as a short side-chain homologue in detergent solution.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. A DFT study on the Cu (1 1 1) surface for ethyl acetate synthesis from ethanol dehydrogenation

    NASA Astrophysics Data System (ADS)

    Li, Ruzhen; Zhang, Minhua; Yu, Yingzhe

    2012-07-01

    Copper-based catalysts have shown excellent catalytic performances. Despite extensive studies in the field, the microscopic mechanism of ethanol dehydrogenation to ethyl acetate (EA) on Cu-based catalysts remains controversial. Aiming to provide insight into the catalytic roles of Cu, density functional theory (DFT) calculations have been performed to study the elementary reactions involved in ethanol dehydrogenation to EA on Cu surfaces. In this work, the adsorption properties of ethanol, ethoxy, acetaldehyde, acetyl and EA on the Cu (1 1 1) catalyst surface were investigated. Based on two pathways, many transition states involved are located. The results show that the route proposed by Colley is more likely to happen.

  3. Optimization of H2SO4-catalyzed hydrothermal pretreatment of rapeseed straw for bioconversion to ethanol: focusing on pretreatment at high solids content.

    PubMed

    Lu, Xuebin; Zhang, Yimin; Angelidaki, Irini

    2009-06-01

    A central composite design of response surface method was used to optimize H(2)SO(4)-catalyzed hydrothermal pretreatment of rapeseed straw, in respect to acid concentration (0.5-2%), treatment time (5-20 min) and solid content (10-20%) at 180 degrees C. Enzymatic hydrolysis and fermentation were also measured to evaluate the optimal pretreatment conditions for maximizing ethanol production. The results showed that acid concentration and treatment time were more significant than solid content for optimization of xylose release and cellulose recovery. Pretreatment with 1% sulfuric acid and 20% solid content for 10 min at 180 degrees C was found to be the most optimal condition for pretreatment of rapeseed straw for ethanol production. After pretreatment at the optimal condition and enzymatic hydrolysis, 75.12% total xylan and 63.17% total glucan were converted to xylose and glucose, respectively. Finally, 66.79% of theoretical ethanol yielded after fermentation.

  4. 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.

  5. A green approach to ethyl acetate: quantitative conversion of ethanol through direct dehydrogenation in a Pd-Ag membrane reactor.

    PubMed

    Zeng, Gaofeng; Chen, Tao; He, Lipeng; Pinnau, Ingo; Lai, Zhiping; Huang, Kuo-Wei

    2012-12-01

    Pincers do the trick: The conversion of ethanol to ethyl acetate and hydrogen was achieved using a pincer-Ru catalyst in a Pd-Ag membrane reactor. Near quantitative conversions and yields could be achieved without the need for acid or base promoters or hydrogen acceptors (see scheme). PMID:23136053

  6. Structural and optical characterizations of ZnO aerogel nanopowder synthesized from zinc acetate ethanolic solution

    NASA Astrophysics Data System (ADS)

    Djouadi, D.; Meddouri, M.; Chelouche, A.

    2014-11-01

    ZnO aerogel powder has been synthesized by a modified sol-gel process using zinc acetate ethanolic solution. XRD, SEM, EDAX, FTIR, UV-visible absorption and photoluminescence (PL) techniques have been used to characterize the as-prepared and the annealed ZnO aerogel powders. The as-prepared ZnO powder has a well-defined polycrystalline hexagonal wurtzite structure. This measurement has demonstrated that the lattice parameters are lower than the standard ones indicating that drying in supercritical conditions of ethanol does not affect the crystallinity but acts as a compressive agent. EDAX measurements show that the obtained aerogel contains only O and Zn elements. Annealing improves the crystallinity in the low DRX angles and decreases the crystalline quality in the high diffraction angles. Also, annealing acts as a tensile agent and increases the lattice parameters. FTIR spectra confirm the annealing effect by the apparition of the strong Zn-O vibration band. The ZnO absorption band shifts to lower wave numbers after annealing indicating an increase in the Zn-O bond length and confirms the XRD results. UV-visible results show a decrease of the ZnO aerogel optical band gap after annealing and confirm the thermal decompression effect on the lattice parameters. The photoluminescence measurements show that the annealing of ZnO aerogel favors the thermal generation of zinc interstitials and oxygen vacancies defects existing in the as-prepared zinc oxide aerogel and shifts the emission toward lower energies.

  7. Kinetics of cytochrome P450 2E1-catalyzed oxidation of ethanol to acetic acid via acetaldehyde.

    PubMed

    Bell-Parikh, L C; Guengerich, F P

    1999-08-20

    The P450 2E1-catalyzed oxidation of ethanol to acetaldehyde is characterized by a kinetic deuterium isotope effect that increases K(m) with no effect on k(cat), and rate-limiting product release has been proposed to account for the lack of an isotope effect on k(cat) (Bell, L. C., and Guengerich, F. P. (1997) J. Biol. Chem. 272, 29643-29651). Acetaldehyde is also a substrate for P450 2E1 oxidation to acetic acid, and k(cat)/K(m) for this reaction is at least 1 order of magnitude greater than that for ethanol oxidation to acetaldehyde. Acetic acid accounts for 90% of the products generated from ethanol in a 10-min reaction, and the contribution of this second oxidation has been overlooked in many previous studies. The noncompetitive intermolecular kinetic hydrogen isotope effects on acetaldehyde oxidation to acetic acid ((H)(k(cat)/K(m))/(D)(k(cat)/K(m)) = 4.5, and (D)k(cat) = 1.5) are comparable with the isotope effects typically observed for ethanol oxidation to acetaldehyde, and k(cat) is similar for both reactions, suggesting a possible common catalytic mechanism. Rapid quench kinetic experiments indicate that acetic acid is formed rapidly from added acetaldehyde (approximately 450 min(-1)) with burst kinetics. Pulse-chase experiments reveal that, at a subsaturating concentration of ethanol, approximately 90% of the acetaldehyde intermediate is directly converted to acetic acid without dissociation from the enzyme active site. Competition experiments suggest that P450 2E1 binds acetic acid and acetaldehyde with relatively high K(d) values, which preclude simple tight binding as an explanation for rate-limiting product release. The existence of a rate-determining step between product formation and release is postulated. Also proposed is a conformational change in P450 2E1 occurring during the course of oxidation and the discrimination of P450 2E1 between acetaldehyde and its hydrated form, the gem-diol. This multistep P450 reaction is characterized by kinetic

  8. 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. PMID:23076570

  9. 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

  10. 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.

  11. 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

  12. A candidate for a single-chain magnet: [Mn3(OAc)6(py)2(H2O)2]n (OAc is acetate and py is pyridine).

    PubMed

    Caballero-Jiménez, Judith; Reyes Ortega, Yasmi; Bernès, Sylvain; Escudero, Roberto

    2014-08-01

    The title complex, catena-poly[di-μ3-acetato-κ(6)O:O:O'-tetra-μ2-acetato-κ(4)O:O;κ(4)O:O'-diaquabis(pyridine-κN)trimanganese(II)], [Mn3(CH3COO)6(C6H5N)2(H2O)2]n, is a true one-dimensional coordination polymer, in which the Mn(II) centres form a zigzag chain along [010]. The asymmetric unit contains two metal centres, one of which (Mn1) lies on an inversion centre, while the other (Mn2) is placed close to an inversion centre on a general position. Since all the acetates behave as bridging ligands, although with different μ2- and μ3-coordination modes, a one-dimensional polymeric structure is formed, based on trinuclear repeat units (Mn1...Mn2...Mn2'), in which the Mn2 and Mn2' sites are related by an inversion centre. Within this monomeric block, the metal-metal separations are Mn1...Mn2 = 3.36180 (18) Å and Mn2...Mn2' = 4.4804 (3) Å. Cation Mn1, located on an inversion centre, displays an [MnO6] coordination sphere, while Mn2, on a general position, has a slightly stronger [MnO5N] ligand field, as the sixth coordination site is occupied by a pyridine molecule. Both centres approximate an octahedral ligand field. The chains are parallel in the crystal structure and interact via hydrogen bonds involving coordinated water molecules. However, the shortest metal-metal separation between two chains [5.3752 (3) Å] is large compared with the intrachain interactions. These structural features are compatible with a single-chain magnet behaviour, as confirmed by preliminary magnetic studies.

  13. Effect of ethanolic extract of leaves of Paederia foetida Linn. on acetic acid induced colitis in albino rats

    PubMed Central

    Das, Swarnamoni; Kanodia, Lalit; Mukherjee, Apurba; Hakim, Abdul

    2013-01-01

    Objectives: To evaluate the effect of ethanolic extract of leaves of Paederia foetida on acetic acid induced colitis in albino rats. Materials and Methods: Ethanolic extract of Paederia foetida (EEPF) was prepared by percolation method. Acute toxicity test was done by using Organization for Economic Cooperation and Development guidelines. Albino rats were divided into four groups of five animals each. Groups A and B received 3% gum acacia. Groups C and D received EEPF 500 mg/kg body weight (BW) and 5-aminosalisylic acid 100 mg/kg BW respectively. Colitis was induced by transrectal administration of 4% acetic acid on 5th day. All animals were sacrificed after 48 h of colitis induction and distal 10 cm of the colon was dissected. Colon was weighed for disease activity index (DAI) and scored macroscopically and microscopically. Biochemical assessment of tissue myeloperoxidase (MPO), catalase (CAT) and superoxide dismutase (SOD) was done in colonic tissue homogenate and malondialdehyde (MDA) was estimated in serum. Results: P. foetida showed significant (P < 0.05) reduction in DAI, macroscopic and microscopic lesion score as well as significant (P < 0.05) improvement in MPO, MDA, CAT, and SOD level as compared to Group B. Conclusions: The ethanolic extract of leaves of P. foetida showed significant amelioration of experimentally induced colitis, which may be attributed to its anti-inflammatory and antioxidant property. PMID:24130378

  14. 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.

  15. 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.

  16. Development of xylose-fermenting yeasts for ethanol production at high acetic acid concentrations

    SciTech Connect

    Mohandas, D.V.; Whelan, D.R.; Panchal, C.J.

    1995-12-31

    Mutants resistant to comparatively high levels of acetic acid were isolated from the xylose-fermenting yeasts Candida shehatae and Pichia Stipitis by adapting these cultures to increasing concentrations of acetic acid grown in shake-flask cultures. These mutants were tested for their ability to ferment xylose in presence of high acetic acid concentrations, in acid hydrolysates of wood, and in hardwood spent sulfite liquor, and compared with their wild-type counterparts and between themselves. The P. stipitis mutant exhibited faster fermentation times, better tolerance to acid hydrolysates, and tolerance to lower pH.

  17. 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)...

  18. 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

  19. 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

  20. 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.

  1. 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. PMID:25282639

  2. Decreasing the Level of Ethyl Acetate in Ethanolic Fermentation Broths of Escherichia coli KO11 by Expression of Pseudomonas putida estZ Esterase†

    PubMed Central

    Hasona, Adnan; York, S. W.; Yomano, L. P.; Ingram, L. O.; Shanmugam, K. T.

    2002-01-01

    During the fermentation of sugars to ethanol relatively high levels of an undesirable coproduct, ethyl acetate, are also produced. With ethanologenic Escherichia coli strain KO11 as the biocatalyst, the level of ethyl acetate in beer containing 4.8% ethanol was 192 mg liter−1. Although the E. coli genome encodes several proteins with esterase activity, neither wild-type strains nor KO11 contained significant ethyl acetate esterase activity. A simple method was developed to rapidly screen bacterial colonies for the presence of esterases which hydrolyze ethyl acetate based on pH change. This method allowed identification of Pseudomonas putida NRRL B-18435 as a source of this activity and the cloning of a new esterase gene, estZ. Recombinant EstZ esterase was purified to near homogeneity and characterized. It belongs to family IV of lipolytic enzymes and contains the conserved catalytic triad of serine, aspartic acid, and histidine. As expected, this serine esterase was inhibited by phenylmethylsulfonyl fluoride and the histidine reagent diethylpyrocarbonate. The native and subunit molecular weights of the recombinant protein were 36,000, indicating that the enzyme exists as a monomer. By using α-naphthyl acetate as a model substrate, optimal activity was observed at pH 7.5 and 40°C. The Km and Vmax for α-naphthyl acetate were 18 μM and 48.1 μmol · min−1 · mg of protein−1, respectively. Among the aliphatic esters tested, the highest activity was obtained with propyl acetate (96 μmol · min−1 · mg of protein−1), followed by ethyl acetate (66 μmol · min−1 · mg of protein−1). Expression of estZ in E. coli KO11 reduced the concentration of ethyl acetate in fermentation broth (4.8% ethanol) to less than 20 mg liter−1. PMID:12039716

  3. The bifunctional aldehyde-alcohol dehydrogenase controls ethanol and acetate production in Entamoeba histolytica under aerobic conditions.

    PubMed

    Pineda, Erika; Encalada, Rusely; Olivos-García, Alfonso; Néquiz, Mario; Moreno-Sánchez, Rafael; Saavedra, Emma

    2013-01-16

    By applying metabolic control analysis and inhibitor titration we determined the degree of control (flux control coefficient) of pyruvate:ferredoxin oxidoreductase (PFOR) and bifunctional aldehyde-alcohol dehydrogenase (ADHE) over the fluxes of fermentative glycolysis of Entamoeba histolytica subjected to aerobic conditions. The flux-control coefficients towards ethanol and acetate formation determined for PFOR titrated with diphenyleneiodonium were 0.07 and 0.09, whereas for ADHE titrated with disulfiram were 0.33 and -0.19, respectively. ADHE inhibition induced significant accumulation of glycolytic intermediates and lower ATP content. These results indicate that ADHE exerts significant flux-control on the carbon end-product formation of amoebas subjected to aerobic conditions. PMID:23201265

  4. 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.

  5. Ethanol-induced increase in portal blood flow: Role of acetate and A sub 1 - and A sub 2 -adenosine receptors

    SciTech Connect

    Carmichael, F.J.; Saldivia, V.; Varghese, G.A.; Israel, Y.; Orrego, H. Univ. of Toronto, Ontario )

    1988-10-01

    The increase in portal blood flow induced by ethanol appears to be adenosine mediated. Acetate, which is released by the liver during ethanol metabolism, is known to increase adenosine levels in tissues and in blood. The effects of acetate on portal blood flow were investigated in rats using the microsphere technique. The intravenous infusion of acetate resulted in vasodilation of the preportal vasculature and in a dose-dependent increase in portal blood flow. This acetate-induced increase in portal blood flow was suppressed by the adenosine receptor blocker, 8-phenyltheophylline. Using the A{sub 1}-adenosine receptor agonist N-6-cyclohexyl adenosine and the A{sub 2}-agonist 5{prime}-N-ethylcarboxamido adenosine, we demonstrate that the effect of adenosine on the preportal vasculature is mediated by the A{sub 2}-subtype of adenosine receptors. In conclusion, these data support the hypothesis that the increase in portal blood flow after ethanol administration results from a preportal vasodilatory effect of adenosine formed from acetate metabolism in extrahepatic tissues.

  6. Partial oxidation of 4-tert-butyltoluene catalyzed by homogeneous cobalt and cerium acetate catalysts in the Br-/H2O2/acetic acid system: insights into selectivity and mechanism.

    PubMed

    van de Water, Leon G A; Kaza, Arati; Beattie, James K; Masters, Anthony F; Maschmeyer, Thomas

    2007-01-01

    The partial oxidation of 4-tert-butyltoluene to 4-tert-butylbenzaldehyde by hydrogen peroxide in glacial acetic acid, catalyzed by bromide ions in combination with cobalt(II) acetate or cerium(III) acetate, has been studied in detail. Based on the observed differences in reaction rates and product distributions for the different catalysts, a reaction mechanism involving two independent pathways is proposed. After the initial formation of a benzylic radical species, either oxidation of this intermediate by the metal catalyst or reaction with bromine generated in situ occurs, depending on which catalyst is used. The first pathway leads to the exclusive formation of 4-tert-butylbenzaldehyde, whereas reaction of the radical intermediate with bromine leads to formation of the observed side products 4-tert-butylbenzyl bromide and its hydrolysis and solvolysis products 4-tert-butylbenzyl alcohol and 4-tert-butylbenzyl acetate, respectively. The cobalt(II) catalysts Co(OAc)(2) and Co(acac)(2) are able to quickly oxidize the radical intermediate, thereby largely preventing the bromination reaction (i.e., side-product formation) from occurring, and yield the aldehyde product with 75-80 % selectivity. In contrast, the cerium catalyst studied here exhibits an aldehyde selectivity of around 50 % due to the competing bromination reaction. Addition of extra hydrogen peroxide leads to an increased product yield of 72 % (cerium(III) acetate) or 58 % (cobalt(II) acetate). Product inhibition and the presence of increasing amounts of water in the reaction mixture do not play a role in the observed low incremental yields.

  7. Spectroscopic and electrochemical properties of group 12 acetates of di-2-pyridylketone thiophene-2-carboxylic acid hydrazone (dpktch-H) complexes. The structure of [Cd(η3-N,N,O-dpktch-H)2

    NASA Astrophysics Data System (ADS)

    Bakir, Mohammed; Lawrence, Mark A. W.; McBean, Shameal

    2015-07-01

    The reaction between [dpktch] and [M(OAc)2] (M = group 12 metal atom) in refluxing CH3CN gave [M(η2-O,O-OAc)(η3-N,N,O-dpktch-H)]·nH2O (n = 0 or 1). The infrared and 1H NMR spectra are consistent with the coordination of [η2-O,O-OAc] and [η3-N,N,O-dpktch-H]- and the proposed formulations. The electronic absorption spectra of [M(η2-O,O-OAc)(η3-N,N,O-dpktch-H)]·nH2O measured in non-aqueous solvents revealed a highly intense intra-ligand-charge transfer (ILCT) transition due to π-π∗ of dpk followed by dpk → thiophene charge transfer. The electronic transitions of [M(η2-O,O-OAc)(η3-N,N,O-dpktch-H)]·nH2O are solvent and concentration dependent. Spectrophotometric titrations of dmso solutions of [M(η2-O,O-OAc)(η3-N,N,O-dpktch-H)]·nH2O with benzoic acid revealed irreversible inter-conversion between [M(η2-O,O-OAc)(η3-N,N,O-dpktch-H)]·nH2O and it conjugate acid [M(η2-O,O-OAc)(η3-N,N,O-dpktch)]·nH2O pointing to ligand exchange between the acetate and benzoate anions. When CH2Cl2 solutions of [M(η2-O,O-OAc)(η3-N,N,O-dpktch-H)]·nH2O were titrated with dmso, changes appeared pointing to solvolysis or ligand exchange reactions. Electrochemical measurements on dmso solutions of [M(η2-O,O-OAc)(η3-N,N,O-dpktch-H)]·nH2O divulged irreversible redox transformations consistent with electrochemical decomposition of [M(η2-O,O-OAc)(η3-N,N,O-dpktch-H)]·nH2O. The solid state structure of a single crystal of [Cd(η3-N,N,O-dpktch-H)2] obtained from a dmso solution of [Cd(η2-O,O-OAc)(η3-N,N,O-dpktch-H)]·nH2O confirmed the ligand scrambling of [M(η2-O,O-OAc)(η3-N,N,O-dpktch-H)]·nH2O. The extended structure of [Cd(η3-N,N,O-dpktch-H)2] revealed stacks of [Cd(η3-N,N,O-dpktch-H)2] locked via a network of hydrogen bonds. A significant amount of empty space (35.5%) was observed in the solid state structure of [Cd(η3-N,N,O-dpktch-H)2].

  8. Protective effects of ascorbic acid, DL-alpha-tocopherol acetate, and sodium selenate on ethanol-induced gastric mucosal injury of rats.

    PubMed

    Ozdil, Sadakat; Yanardag, Refiye; Koyuturk, Meral; Bolkent, Sehnaz; Arbak, Serap

    2004-01-01

    In this study, the effect of ascorbic acid (vitamin C), DL-alpha-tocopherol acetate (vitamin E), and sodium selenate (selenium) on ethanol-induced gastric mucosal injury in rats was investigated morphologically and biochemically. The gastric mucosal injury was produced by administration of 1 mL of absolute ethanol to each rat. Animals received vitamin C (250 mg/kg), vitamin E (250 mg/kg), and selenium (0.5 mg/kg) for 3 d 1 h prior to the administration of absolute ethanol. In gastric mucosa of rats given ethanol according to control groups, neuronal nitric oxide expression decreased. This immunoreactivity was much lower in the group given ethanol+vitamin C+vitamin E+selenium than the control group and the ethanol-induced group. Scanning electron microscopic evaluation of the ethanol-induced group, when compared to control groups, revealed degenerative changes in gastric mucosa, whereas a good arrangement in surface topography of gastric mucosa in the group given ethanol + vitamin C+vitamin E + selenium was observed. In the group administered ethanol, a reduction of the stomach glutathione (GSH) and serum total protein levels and increases in serum sialic acid, triglycerides, and stomach lipid peroxidation (LPO) levels were observed. Vitamin C+vitamin E+Se administration to alcohol-treated rats significantly increased the serum total protein, triglyceride levels, and stomach GSH levels and significantly lowered the levels of serum sialic acid and stomach LPO compared to untreated alcohol-supplemented rats. As a result of these findings, we can say that the combination of vitamin C, vitamin E, and selenium has a protective effect on ethanol-induced gastric mucosal injury of rats.

  9. High Activity of Ce1-xNixO2-y for H2 Production through Ethanol Steam Reforming: Tuning Catalytic Performance through Metal↔Oxide Interactions

    SciTech Connect

    Rodriguez, J.A.; Zhou, G.; Barrio, L.; Agnoli, S.; Senanayake, S.D.; Evans, J.; Kubacka, A.; Estrella, M.; Hanson, J.C.; Martínez-Arias, A.; Fernández-García, M.

    2010-12-10

    Ce{sub 0.8}Ni{sub 0.2}O{sub 2-y} is an excellent catalyst for ethanol steam reforming. Metal-oxide interactions perturb the electronic properties of the small particles of metallic nickel present in the catalyst under the reaction conditions and thus suppress any methanation activity. The nickel embedded in ceria induces the formation of O vacancies, which facilitate cleavage of the O-H bonds in ethanol and water.

  10. 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%.

  11. Protective effects of ascorbic acid, dl-alpha-tocopherol acetate, and sodium selenate on ethanol-induced liver damage of rats.

    PubMed

    Ozdil, Sadakat; Bolkent, Sehnaz; Yanardag, Refiye; Arda-Pirincci, Pelin

    2004-02-01

    In this study, the effect of a combination of vitamin C (ascorbic acid), vitamin E (dl-alpha-tocopherol acetate), and selenium (sodium selenate) on ethanol-induced liver damage in rats was investigated, morphologically and biochemically. The ethanol-induced injury was produced by the administration of 1 mL of absolute ethanol to each rat. Animals received vitamin C (250 mg/kg), vitamin E (250 mg/kg), and selenium (0.5 mg/kg) (ViCESe) for 3 d 1 h prior to the administration of absolute ethanol. In the liver of the animals given ethanol, the degenerative changes such as extreme hyperemia, vacuolization in cells of portal areas, a dilation in sinusoids, mononuclear cell infiltration, a swelling in cisternae of granular endoplasmic reticulum and in mitochondrial cristae, an increase in smooth endoplasmic reticulum, many lipid vacuoles were observed both light and electron microscopically. A similar structure was usually distinguished when compared with control animals, in rats given ethanol + ViCESe. In this group, the findings indicating cellular damage were either not observed at all or were decreased. In the group administered ethanol, a reduction of the blood glutathione (GSH) level and increases in serum values of alanine aminotranserase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), and gamma-glutamyl transferase (GGT) activities were observed, whereas in the control group, the reverse was found to occur. On the other hand, in the group in which ethanol + ViCESe was administered, it was observed that the blood GSH value and serum ALP and ALT activities increased and serum AST, LDH, and GGT activities decreased. As a result, the present study indicates that ViCESe because of their antioxidant activity against ethanol damage have a protective effect on the liver.

  12. Role of structural H 2O in TiO 2 nanotubes in enhancing Pt/C direct ethanol fuel cell anode electro-catalysts

    NASA Astrophysics Data System (ADS)

    Song, Huanqiao; Qiu, Xinping; Guo, Daojun; Li, Fushen

    TiO 2 nanotubes (TNTs) with different structural water were obtained by heat treatment under different temperatures. The role of the structural water in TNTs co-catalyzing ethanol oxidation with Pt/C catalyst was studied systematically. Electrochemical studies using cyclic voltammetry and CO stripping voltammetry indicated that more structural water in TNTs was favorable for improving the tolerance of Pt/C to poisoning species; while chronoamperometry curves and repeated cyclic voltammograms showed that slightly less structural water in TNTs actually led to higher catalytic activity and better stability of Pt/C catalysts for ethanol oxidation. This strange result has been analyzed and was ascribed to the appropriate balance of bi-functional mechanism and ethanol transfer in the catalyst layer with less structural water.

  13. Modeling of breakthrough curves of single and quaternary mixtures of ethanol, glucose, glycerol and acetic acid adsorption onto a microporous hyper-cross-linked resin.

    PubMed

    Zhou, Jingwei; Wu, Jinglan; Liu, Yanan; Zou, Fengxia; Wu, Jian; Li, Kechun; Chen, Yong; Xie, Jingjing; Ying, Hanjie

    2013-09-01

    The adsorption of quaternary mixtures of ethanol/glycerol/glucose/acetic acid onto a microporous hyper-cross-linked resin HD-01 was studied in fixed beds. A mass transport model based on film solid linear driving force and the competitive Langmuir isotherm equation for the equilibrium relationship was used to develop theoretical fixed bed breakthrough curves. It was observed that the outlet concentration of glucose and glycerol exceeded the inlet concentration (c/c0>1), which is an evidence of competitive adsorption. This phenomenon can be explained by the displacement of glucose and glycerol by ethanol molecules, owing to more intensive interactions with the resin surface. The model proposed was validated using experimental data and can be capable of foresee reasonably the breakthrough curve of specific component under different operating conditions. The results show that HD-01 is a promising adsorbent for recovery of ethanol from the fermentation broth due to its large capacity, high selectivity, and rapid adsorption rate.

  14. 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.

  15. Upgrading oxygenated Fischer-Tropsch derivatives and one-step direct synthesis of ethyl acetate from ethanol - examples of the desirability of research on simple chemical compounds transformations.

    PubMed

    Klimkiewicz, Roman

    2014-01-01

    Oxygenates formed as by-products of Fischer-Tropsch syntheses can be transformed into other Fischer-Tropsch derived oxygenates instead of treating them as unwanted chemicals. One-step direct synthesis of ethyl acetate from ethanol is feasible with the use of some heterogeneous catalysts. Despite their apparent simplicity, both transformations are discussed as targeted fields of research. Furthermore, the two concepts are justified due to the environmental protection. Arguments regarding the Fischer-Tropsch process are focused on the opportunities of the utilization of undesirable by-products. The effective striving for their utilization can make the oxygenates the targeted products of this process. Arguments regarding the one-step direct synthesis of ethyl acetate underline the environmental protection and sustainability as a less waste-generating method but, above all, highlight the possibility of reducing the glycerol overproduction problem. The production of ethyl acetate from bioethanol and then transesterification of fats and oils with the use of ethyl acetate allows managing all the renewable raw materials. Thus, the process enables the biosynthesis of biodiesel without glycerine by-product and potentially would result in the increase in the demand for ethyl acetate. Graphical Abstract.

  16. 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. PMID:27314669

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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...

  2. 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.

  3. Monolayer structures of niobic acids supported on SiO[sub 2] and their catalytic activities for esterification of acetic acid with ethanol

    SciTech Connect

    Shirai, Masayuki; Asakura, Kiyotaka; Iwasawa, Yasuhiro )

    1991-11-28

    New submonolayer niobic acid catalysts were prepared by the reaction of Nb(OC[sub 2]H[sub 5])[sub 5] with surface OH groups of SiO[sub 2], followed by H[sub 2]O treatment. The surface structures were characterized by means of EXAFS, XRD, XRF, and FT-IR. The niobic acids on SiO[sub 2] up to 8.0 wt % Nb loadings were found to grow in a monolayer mode. These catalysts showed activities 20 times as large as that of a niobic acid bulk catalyst for the esterification of acetic acid with ethanol. The activity was referred to Lewis acid sites in the monolayer structure, which was stable even after evacuation at high temperatures such as 873 K.

  4. H2 blockers

    MedlinePlus

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

  5. 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 ...

  6. Supercritical carbon dioxide combined with 1-butyl-3-methylimidazolium acetate and ethanol for the pretreatment and enzymatic hydrolysis of sugarcane bagasse.

    PubMed

    Silveira, Marcos Henrique Luciano; Vanelli, Bruno Angelo; Corazza, Marcos Lucio; Ramos, Luiz Pereira

    2015-09-01

    The use of green solvents for the partial delignification of milled sugarcane bagasse (1mm particle size) and for the enhancement of its susceptibility to enzymatic hydrolysis was demonstrated. The experiments were carried out for 2h using 40 g of supercritical carbon dioxide combined with 1-butyl-3-methylimidazolium acetate and 15.8 g of ethanol. The effects of temperature (110-180 °C), pressure (195-250 bar) and IL-to-bagasse mass ratio (0:1-1:1) were investigated through a factorial design in which the response variables were the extent of delignification and both anhydroglucose and anhydroxylose contents in the pretreated materials. The highest delignification degree (41%) led to the best substrate for hydrolysis, giving a 70.7 wt% glucose yield after 12h using 5 wt% and Cellic CTec2® (Novozymes) at 10 mg g(-1) total solids. Hence, excellent substrates for hydrolysis were produced with a minimal IL requirement, which could be recovered by ethanol washing for its downstream processing and reuse. PMID:26056781

  7. Supercritical carbon dioxide combined with 1-butyl-3-methylimidazolium acetate and ethanol for the pretreatment and enzymatic hydrolysis of sugarcane bagasse.

    PubMed

    Silveira, Marcos Henrique Luciano; Vanelli, Bruno Angelo; Corazza, Marcos Lucio; Ramos, Luiz Pereira

    2015-09-01

    The use of green solvents for the partial delignification of milled sugarcane bagasse (1mm particle size) and for the enhancement of its susceptibility to enzymatic hydrolysis was demonstrated. The experiments were carried out for 2h using 40 g of supercritical carbon dioxide combined with 1-butyl-3-methylimidazolium acetate and 15.8 g of ethanol. The effects of temperature (110-180 °C), pressure (195-250 bar) and IL-to-bagasse mass ratio (0:1-1:1) were investigated through a factorial design in which the response variables were the extent of delignification and both anhydroglucose and anhydroxylose contents in the pretreated materials. The highest delignification degree (41%) led to the best substrate for hydrolysis, giving a 70.7 wt% glucose yield after 12h using 5 wt% and Cellic CTec2® (Novozymes) at 10 mg g(-1) total solids. Hence, excellent substrates for hydrolysis were produced with a minimal IL requirement, which could be recovered by ethanol washing for its downstream processing and reuse.

  8. Vapor-phase esterification of acetic acid with ethanol catalyzed by a macroporous sulfonated styrene-divinylbenzene (20%) resin

    SciTech Connect

    Gimenez, J.; Costa, J.; Cervera, S.

    1987-02-01

    The kinetics of the vapor-phase (85-120/sup 0/C) esterification of acetic acid with ethyl alcohol, at atmospheric pressure, catalyzed by a macroporous sulfonated styrene-divinylbenzene (DVB;20%) resin, has been studied. A simple first-order model (r = kp/sub 1/) fits experimental kinetic data properly for a constant reactants ratio. Discussion by means of L-H-H-W models shows that the rate-controlling step is the surface reaction with a single-site mechanism. The apparent activation energy is 4000 cal/mol.

  9. 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.

  10. 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.

  11. 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. PMID:23036453

  12. 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

    2014-01-01

    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.

  13. 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

  14. Acetate Production by Methanogenic Bacteria

    PubMed Central

    Westermann, Peter; Ahring, Birgitte K.; Mah, Robert A.

    1989-01-01

    Methanosarcina barkeri MS and 227 and Methanosarcina mazei S-6 produced acetate when grown on H2-CO2, methanol, or trimethylamine. Marked differences in acetate production by the two bacterial species were found, even though methane and cell yields were nearly the same. M. barkeri produced 30 to 75 μmol of acetate per mmol of CH4 formed, but M. mazei produced only 8 to 9 μmol of acetate per mmol of CH4. PMID:16348006

  15. Peat: home to novel syntrophic species that feed acetate- and hydrogen-scavenging methanogens.

    PubMed

    Schmidt, Oliver; Hink, Linda; Horn, Marcus A; Drake, Harold L

    2016-08-01

    Syntrophic bacteria drive the anaerobic degradation of certain fermentation products (e.g., butyrate, ethanol, propionate) to intermediary substrates (e.g., H2, formate, acetate) that yield methane at the ecosystem level. However, little is known about the in situ activities and identities of these syntrophs in peatlands, ecosystems that produce significant quantities of methane. The consumption of butyrate, ethanol or propionate by anoxic peat slurries at 5 and 15 °C yielded methane and CO2 as the sole accumulating products, indicating that the intermediates H2, formate and acetate were scavenged effectively by syntrophic methanogenic consortia. 16S rRNA stable isotope probing identified novel species/strains of Pelobacter and Syntrophomonas that syntrophically oxidized ethanol and butyrate, respectively. Propionate was syntrophically oxidized by novel species of Syntrophobacter and Smithella, genera that use different propionate-oxidizing pathways. Taxa not known for a syntrophic metabolism may have been involved in the oxidation of butyrate (Telmatospirillum-related) and propionate (unclassified Bacteroidetes and unclassified Fibrobacteres). Gibbs free energies (ΔGs) for syntrophic oxidations of ethanol and butyrate were more favorable than ΔGs for syntrophic oxidation of propionate. As a result of the thermodynamic constraints, acetate transiently accumulated in ethanol and butyrate treatments but not in propionate treatments. Aceticlastic methanogens (Methanosarcina, Methanosaeta) appeared to outnumber hydrogenotrophic methanogens (Methanocella, Methanoregula), reinforcing the likely importance of aceticlastic methanogenesis to the overall production of methane. ΔGs for acetogenesis from H2 to CO2 approximated to -20 kJ mol(-1) when acetate concentrations were low, indicating that acetogens may have contributed to the flow of carbon and reductant towards methane. PMID:26771931

  16. 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. PMID:27392628

  17. 9-[(2-Hy-droxy-benzyl-idene)amino]-11-(2-hy-droxy-phen-yl)-10,13-diphenyl-8-oxa-12-azoniatricyclo-[7.3.1.0]trideca-2(7),3,5-triene acetate ethanol disolvate.

    PubMed

    Anh, Le Tuan; Hieu, Truong Hong; Soldatenkov, Anatoly T; Soldatova, Svetlana A; Khrustalev, Victor N

    2011-01-01

    The title compound, C(36)H(31)N(2)O(3) (+),C(2)H(3)O(2) (-)·2C(2)H(5)OH, the product of a domino condensation of dibenzyl ketone with salicylic aldehyde and ammonium acetate, crystallized as the ethanol disolvate. The cation of the salt comprises a fused tricyclic system containing three six-membered rings (piperidine, dihydro-2H-pyran and benzene). The piperidine ring has the usual chair conformation, while the dihydro-pyran ring adopts a slightly distorted sofa conformation. In the crystal, there are six (one intra- and five inter-molecular) independent hydrogen-bonding inter-actions: the inter-molecular hydrogen bonds link the cations and anions and ethanol solvent mol-ecules into ribbons along [001]. The ribbons are stacked along the a axis. PMID:21522325

  18. 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.

  19. MELCOR-H2

    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,more » 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.« less

  20. 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.

  1. 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. PMID:25755072

  2. H2 oxidation versus organic substrate oxidation in non-heme iron mediated reactions with H2O2.

    PubMed

    Hassanpour, Azin; Acuña-Parés, Ferran; Luis, Josep M; Cusso, Olaf; Morales de la Rosa, Silvia; Campos-Martín, José Miguel; Fierro, Jose L G; Costas, Miquel; Lloret-Fillol, Julio; Mas-Ballesté, Rubén

    2015-10-18

    Herein we show that species generated upon reaction of α-[Fe(CF3SO3)2(BPMCN)] (BPMCN = N,N'-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane) with H2O2 (putatively [Fe(V)(O)(OH)(BPMCN)]) is able to efficiently oxidize H2 to H2O even in the presence of organic substrates, while species formed in the presence of acetic acid (putatively [Fe(V)(O)(OAc)(BPMCN)]) prefer organic substrate oxidation over H2 activation. Mechanistic implications have been analysed with the aid of computational methods.

  3. [The activity of 2',5'-oligoadenylate-synthetase in rat spleen lymphocytes in the chronic ethanol intoxication and administration of zinc acetate].

    PubMed

    Chaĭka, V O; Kompanets', I V; Hadiliia, O P; Kharchenko, O I; Ostapchenko, L I

    2010-01-01

    It was shown that the activity of interferon-induced enzyme 2',5'-oligoadenylate-synthetase is suppressed in rat spleen lymphocytes under the chronic alcohol intoxication. The values of enzyme activity were minimal under the long-term action of etanol (21 day). The combined administration of zinc acetate and etanol to rats causes the increase of enzyme activity, the effect is most expressed on the late stages of alcohol intoxication development.

  4. The metabolome of Chlamydomonas reinhardtii following induction of anaerobic H2 production by sulfur depletion.

    PubMed

    Matthew, Timmins; Zhou, Wenxu; Rupprecht, Jens; Lim, Lysha; Thomas-Hall, Skye R; Doebbe, Anja; Kruse, Olaf; Hankamer, Ben; Marx, Ute C; Smith, Steven M; Schenk, Peer M

    2009-08-28

    The metabolome of the model species Chlamydomonas reinhardtii has been analyzed during 120 h of sulfur depletion to induce anaerobic hydrogen (H(2)) production, using NMR spectroscopy, gas chromatography coupled to mass spectrometry, and TLC. The results indicate that these unicellular green algae consume freshly supplied acetate in the medium to accumulate energy reserves during the first 24 h of sulfur depletion. In addition to the previously reported accumulation of starch, large amounts of triacylglycerides were deposited in the cells. During the early 24- to 72-h time period fermentative energy metabolism lowered the pH, H(2) was produced, and amino acid levels generally increased. In the final phase from 72 to 120 h, metabolism slowed down leading to a stabilization of pH, even though some starch and most triacylglycerides remained. We conclude that H(2) production does not slow down due to depletion of energy reserves but rather due to loss of essential functions resulting from sulfur depletion or due to a build-up of the toxic fermentative products formate and ethanol. PMID:19478077

  5. 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

  6. 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%).

  7. 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.

  8. Garlic Oil and Vitamin E Prevent the Adverse Effects of Lead Acetate and Ethanol Separately as well as in Combination in the Drinking Water of Rats

    PubMed Central

    Sajitha, G. R.; Jose, Regi; Andrews, A.; Ajantha, K. G.; Augustine, Paul

    2010-01-01

    Daily feeding of drinking water containing lead acetate (160 mg/l) or 10% alcohol by volume or a combination of both to rats for a month produced certain deleterious effects through oxidative stress. Both heavy metal lead and alcohol are capable of doing such damages. The deleterious alterations observed were in the parameters of blood, serum and tissues, viz; Hb, Pb, proteins, lipids, lipid per oxidation, Vitamins C and E levels and enzyme activities of AST, ALT, and catalase. Simultaneous feeding of either of the two antioxidants garlic oil (GO) and vitamin E at equal doses of 100 mg/kg/day, to the rats counteracted the deleterious effects of the above two chemicals significantly. The maximum damage was brought about by feeding of drinking water containing both lead acetate and alcohol. The protective effects of GO and Vitamin E were not significantly different. The mechanism of actions of the Vitamin E and GO is probably due to their efficiency as detoxifying agents and antioxidants, to scavenging free radicals as well as an independent action of GO on the removal of lead salt as lead sulfide. PMID:21731199

  9. Garlic Oil and Vitamin E Prevent the Adverse Effects of Lead Acetate and Ethanol Separately as well as in Combination in the Drinking Water of Rats.

    PubMed

    Sajitha, G R; Jose, Regi; Andrews, A; Ajantha, K G; Augustine, Paul; Augusti, K T

    2010-07-01

    Daily feeding of drinking water containing lead acetate (160 mg/l) or 10% alcohol by volume or a combination of both to rats for a month produced certain deleterious effects through oxidative stress. Both heavy metal lead and alcohol are capable of doing such damages. The deleterious alterations observed were in the parameters of blood, serum and tissues, viz; Hb, Pb, proteins, lipids, lipid per oxidation, Vitamins C and E levels and enzyme activities of AST, ALT, and catalase. Simultaneous feeding of either of the two antioxidants garlic oil (GO) and vitamin E at equal doses of 100 mg/kg/day, to the rats counteracted the deleterious effects of the above two chemicals significantly. The maximum damage was brought about by feeding of drinking water containing both lead acetate and alcohol. The protective effects of GO and Vitamin E were not significantly different. The mechanism of actions of the Vitamin E and GO is probably due to their efficiency as detoxifying agents and antioxidants, to scavenging free radicals as well as an independent action of GO on the removal of lead salt as lead sulfide. PMID:21731199

  10. 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....

  11. 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.

  12. 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.

  13. Analysis of proteins responsive to acetic acid in Acetobacter: molecular mechanisms conferring acetic acid resistance in acetic acid bacteria.

    PubMed

    Nakano, Shigeru; Fukaya, Masahiro

    2008-06-30

    Acetic acid bacteria are used for industrial vinegar production because of their remarkable ability to oxidize ethanol and high resistance to acetic acid. Although several molecular machineries responsible for acetic acid resistance in acetic acid bacteria have been reported, the entire mechanism that confers acetic acid resistance has not been completely understood. One of the promising methods to elucidate the entire mechanism is global analysis of proteins responsive to acetic acid by two-dimensional gel electrophoresis. Recently, two proteins whose production was greatly enhanced by acetic acid in Acetobacter aceti were identified to be aconitase and a putative ABC-transporter, respectively; furthermore, overexpression or disruption of the genes encoding these proteins affected acetic acid resistance in A. aceti, indicating that these proteins are involved in acetic acid resistance. Overexpression of each gene increased acetic acid resistance in Acetobacter, which resulted in an improvement in the productivity of acetic acid fermentation. Taken together, the results of the proteomic analysis and those of previous studies indicate that acetic acid resistance in acetic acid bacteria is conferred by several mechanisms. These findings also provide a clue to breed a strain having high resistance to acetic acid for vinegar fermentation.

  14. Effects of extracellular pH on the metabolic pathways in sulfur-deprived, H2-producing Chlamydomonas reinhardtii cultures.

    PubMed

    Kosourov, Sergey; Seibert, Michael; Ghirardi, Maria L

    2003-02-01

    Sustained photoproduction of H(2) by the green alga, Chlamydomonas reinhardtii, can be obtained by incubating cells in sulfur-deprived medium [Ghirardi et al. (2000b) Trends Biotechnol. 18: 506; Melis et al. (2000) Plant Physiol. 122: 127]. The current work focuses on (a) the effects of different initial extracellular pHs on the inactivation of photosystem II (PSII) and O(2)-sensitive H(2)-production activity in sulfur-deprived algal cells and (b) the relationships among H(2)-production, photosynthetic, aerobic and anaerobic metabolisms under different pH regimens. The maximum rate and yield of H(2) production occur when the pH at the start of the sulfur deprivation period is 7.7 and decrease when the initial pH is lowered to 6.5 or increased to 8.2. The pH profile of hydrogen photoproduction correlates with that of the residual PSII activity (optimum pH 7.3-7.9), but not with the pH profiles of photosynthetic electron transport through photosystem I or of starch and protein degradation. In vitro hydrogenase activity over this pH range is much higher than the actual in situ rates of H(2) production, indicating that hydrogenase activity per se is not limiting. Starch and protein catabolisms generate formate, acetate and ethanol; contribute some reductant for H(2) photoproduction, as indicated by 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 2,5-dibromo-6-isopropyl-3-methyl-1,4-benzoquinone inhibition results; and are the primary sources of reductant for respiratory processes that remove photosynthetically generated O(2). Carbon balances demonstrate that alternative metabolic pathways predominate at different pHs, and these depend on whether residual photosynthetic activity is present or not. PMID:12610217

  15. 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

  16. 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…

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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

  2. 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

  3. 9-[(2-Hy­droxy­benzyl­idene)amino]-11-(2-hy­droxy­phen­yl)-10,13-diphenyl-8-oxa-12-azoniatricyclo­[7.3.1.02,7]trideca-2(7),3,5-triene acetate ethanol disolvate

    PubMed Central

    Anh, Le Tuan; Hieu, Truong Hong; Soldatenkov, Anatoly T.; Soldatova, Svetlana A.; Khrustalev, Victor N.

    2011-01-01

    The title compound, C36H31N2O3 +,C2H3O2 −·2C2H5OH, the product of a domino condensation of dibenzyl ketone with salicylic aldehyde and ammonium acetate, crystallized as the ethanol disolvate. The cation of the salt comprises a fused tricyclic system containing three six-membered rings (piperidine, dihydro-2H-pyran and benzene). The piperidine ring has the usual chair conformation, while the dihydro­pyran ring adopts a slightly distorted sofa conformation. In the crystal, there are six (one intra- and five inter­molecular) independent hydrogen-bonding inter­actions: the inter­molecular hydrogen bonds link the cations and anions and ethanol solvent mol­ecules into ribbons along [001]. The ribbons are stacked along the a axis. PMID:21522325

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

    DOE PAGES

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

    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

  5. 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.

  6. Effect of various factors on ethanol yields from lignocellulosic biomass by Thermoanaerobacterium AK₁₇.

    PubMed

    Almarsdottir, Arnheidur Ran; Sigurbjornsdottir, Margret Audur; Orlygsson, Johann

    2012-03-01

    The ethanol production capacity from sugars and lignocellulosic biomass hydrolysates (HL) by Thermoanaerobacterium strain AK(17) was studied in batch cultures. The strain converts various carbohydrates to, acetate, ethanol, hydrogen, and carbon dioxide. Ethanol yields on glucose and xylose were 1.5 and 1.1 mol/mol sugars, respectively. Increased initial glucose concentration inhibited glucose degradation and end product formation leveled off at 30 mM concentrations. Ethanol production from 5 g L(-1) of complex biomass HL (grass, hemp, wheat straw, newspaper, and cellulose) (Whatman paper) pretreated with acid (0.50% H(2) SO(4)), base (0.50% NaOH), and without acid/base (control) and the enzymes Celluclast and Novozyme 188 (0.1 mL g(-1) dw; 70 and 25 U g(-1) of Celluclast and Novozyme 188, respectively) was investigated. Highest ethanol yields (43.0 mM) were obtained on cellulose but lowest on hemp leafs (3.6 mM). Chemical pretreatment increased ethanol yields substantially from lignocellulosic biomass but not from cellulose. The influence of various factors (HL, enzyme, and acid/alkaline concentrations) on end-product formation from 5 g L(-1) of grass and cellulose was further studied to optimize ethanol production. Highest ethanol yields (5.5 and 8.6 mM ethanol g(-1) grass and cellulose, respectively) were obtained at very low HL concentrations (2.5 g L(-1)); with 0.25% acid/alkali (v/v) and 0.1 mL g(-1) enzyme concentrations. Inhibitory effects of furfural and hydroxymethylfurfural during glucose fermentation, revealed a total inhibition in end product formation from glucose at 4 and 6 g L(-1), respectively. PMID:22012653

  7. Clostridium amylolyticum sp. nov., isolated from H2-producing UASB granules.

    PubMed

    Song, Lei; Dong, Xiuzhu

    2008-09-01

    A Gram-stain-positive, strictly anaerobic, mesophilic, amylolytic, rod-shaped bacterium, designated strain SW408(T), was isolated from a laboratory-scale H(2)-producing upflow anaerobic sludge blanket reactor. The strain grew at 24-45 degrees C (no growth at or below 22 degrees C or at or above 47 degrees C), with optimum growth at 37 degrees C. The pH range for growth was 4.0-9.0 (no growth at or below pH 3.6 or at or above pH 9.3), with optimum growth at pH 7.0. Starch, cellobiose, glucose, fructose, galactose, lactose, maltose, mannose, ribose and sucrose supported growth. The major end products from glucose fermentation were ethanol, acetate, hydrogen and carbon dioxide. Abundant H(2) was produced from starch fermentation. The DNA G+C content was 33.1 mol% (T(m) method). Phylogenetic analysis based on 16S rRNA gene sequence analysis showed that the bacterium represents a previously unrecognized species within Clostridium rRNA cluster I and is most closely related to the type strain of Clostridium frigidicarnis (94.9% similarity). On the basis of phenotypic, genotypic and phylogenetic characteristics, strain SW408(T) was identified as a representative of a novel species of the genus Clostridium, for which the name Clostridium amylolyticum sp. nov. is proposed. The type strain is SW408(T) (=JCM 14823(T)=AS 1.5069(T)=CGMCC 1.5069(T)).

  8. Multi-enzyme catalyzed rapid ethanol lowering in vitro.

    PubMed

    Whitmire, D R; Chambers, R P; Dillon, A R

    1991-10-01

    Ethanol was oxidized to acetate by an enzyme system using yeast alcohol dehydrogenase (YADH), yeast aldehyde dehydrogenase (YALDH), and lactic dehydrogenase (LDH) recycling NAD in two model duodenal fluids and in canine duodenal aspirate in vitro. Sufficient enzyme activities were maintained to convert as much as 34% of the original ethanol to acetate with negligible acetaldehyde accumulation.

  9. 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.

  10. 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

  11. Hydrogen production by immobilized R. faecalis RLD-53 using soluble metabolites from ethanol fermentation bacteria E. harbinense B49.

    PubMed

    Liu, Bing-Feng; Ren, Nan-Qi; Xing, De-Feng; Ding, Jie; Zheng, Guo-Xiang; Guo, Wan-Qian; Xu, Ji-Fei; Xie, Guo-Jun

    2009-05-01

    In order to increase the hydrogen yield from glucose, hydrogen production by immobilized Rhodopseudomonas faecalis RLD-53 using soluble metabolites from ethanol fermentation bacteria Ethanoligenens harbinense B49 was investigated. The soluble metabolites from dark-fermentation mainly were ethanol and acetate, which could be further utilized for photo-hydrogen production. Hydrogen production by B49 was noticeably affected by the glucose and phosphate buffer concentration. The maximum hydrogen yield (1.83 mol H(2)/mol glucose) was obtained at 9 g/l glucose. In addition, we found that the ratio of acetate/ethanol (A/E) increased with increasing phosphate buffer concentration, which is favorable to further photo-hydrogen production. The total hydrogen yield during dark- and photo-fermentation reached its maximum value (6.32 mol H(2)/mol glucose) using 9 g/l glucose, 30 mmol/l phosphate buffers and immobilized R. faecalis RLD-53. Results demonstrated that the combination of dark- and photo- fermentation was an effective and efficient process to improve hydrogen yield from a single substrate. PMID:19200719

  12. 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.

  13. 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

    2016-07-01

    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.

  14. 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

    2016-07-01

    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. PMID:27090191

  15. 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. PMID:27161975

  16. Growth of geobacter sulfurreducens with acetate in syntrophic cooperation with hydrogen-oxidizing anaerobic partners

    PubMed

    Cord-Ruwisch; Lovley; Schink

    1998-06-01

    Pure cultures of Geobacter sulfurreducens and other Fe(III)-reducing bacteria accumulated hydrogen to partial pressures of 5 to 70 Pa with acetate, butyrate, benzoate, ethanol, lactate, or glucose as the electron donor if electron release to an acceptor was limiting. G. sulfurreducens coupled acetate oxidation with electron transfer to an anaerobic partner bacterium in the absence of ferric iron or other electron acceptors. Cocultures of G. sulfurreducens and Wolinella succinogenes with nitrate as the electron acceptor degraded acetate efficiently and grew with doubling times of 6 to 8 h. The hydrogen partial pressures in these acetate-degrading cocultures were considerably lower, in the range of 0.02 to 0.04 Pa. From these values and the concentrations of the other reactants, it was calculated that in this cooperation the free energy change available to G. sulfurreducens should be about -53 kJ per mol of acetate oxidized, assuming complete conversion of acetate to CO2 and H2. However, growth yields (18.5 g of dry mass per mol of acetate for the coculture, about 14 g for G. sulfurreducens) indicated considerably higher energy gains. These yield data, measurement of hydrogen production rates, and calculation of the diffusive hydrogen flux indicated that electron transfer in these cocultures may not proceed exclusively via interspecies hydrogen transfer but may also proceed through an alternative carrier system with higher redox potential, e.g., a c-type cytochrome that was found to be excreted by G. sulfurreducens into the culture fluid. Syntrophic acetate degradation was also possible with G. sulfurreducens and Desulfovibrio desulfuricans CSN but only with nitrate as electron acceptor. These cultures produced cell yields of 4.5 g of dry mass per mol of acetate, to which both partners contributed at about equal rates. These results demonstrate that some Fe(III)-reducing bacteria can oxidize organic compounds under Fe(III) limitation with the production of hydrogen

  17. 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.

  18. 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. PMID

  19. 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

  20. Crystal structures of heterotypic nucleosomes containing histones H2A.Z and H2A

    PubMed Central

    Horikoshi, Naoki; Arimura, Yasuhiro; Taguchi, Hiroyuki; Kurumizaka, Hitoshi

    2016-01-01

    H2A.Z is incorporated into nucleosomes located around transcription start sites and functions as an epigenetic regulator for the transcription of certain genes. During transcriptional regulation, the heterotypic H2A.Z/H2A nucleosome containing one each of H2A.Z and H2A is formed. However, previous homotypic H2A.Z nucleosome structures suggested that the L1 loop region of H2A.Z would sterically clash with the corresponding region of canonical H2A in the heterotypic nucleosome. To resolve this issue, we determined the crystal structures of heterotypic H2A.Z/H2A nucleosomes. In the H2A.Z/H2A nucleosome structure, the H2A.Z L1 loop structure was drastically altered without any structural changes of the canonical H2A L1 loop, thus avoiding the steric clash. Unexpectedly, the heterotypic H2A.Z/H2A nucleosome is more stable than the homotypic H2A.Z nucleosome. These data suggested that the flexible character of the H2A.Z L1 loop plays an essential role in forming the stable heterotypic H2A.Z/H2A nucleosome. PMID:27358293

  1. 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.

  2. 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. PMID:27118074

  3. 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. ...

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

    PubMed

    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 {(1)H}-(15)N 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

  5. 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

  6. 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.

  7. Ethanol Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This book chapter reviews the current process technologies for fuel ethanol production. In the US, almost all commercial fuel ethanol is produced from corn whereas cane sugar is used almost exclusively in Brazil. In Europe, two major types of feedstock considered for fuel ethanol production are be...

  8. 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.

  9. Chemolithotrophic acetogenic H2/CO2 utilization in Italian rice field soil.

    PubMed

    Liu, Fanghua; Conrad, Ralf

    2011-09-01

    Acetate oxidation in Italian rice field at 50 °C is achieved by uncultured syntrophic acetate oxidizers. As these bacteria are closely related to acetogens, they may potentially also be able to synthesize acetate chemolithoautotrophically. Labeling studies using exogenous H(2) (80%) and (13)CO(2) (20%), indeed demonstrated production of acetate as almost exclusive primary product not only at 50 °C but also at 15 °C. Small amounts of formate, propionate and butyrate were also produced from (13)CO(2). At 50 °C, acetate was first produced but later on consumed with formation of CH(4). Acetate was also produced in the absence of exogenous H(2) albeit to lower concentrations. The acetogenic bacteria and methanogenic archaea were targeted by stable isotope probing of ribosomal RNA (rRNA). Using quantitative PCR, (13)C-labeled bacterial rRNA was detected after 20 days of incubation with (13)CO(2). In the heavy fractions at 15 °C, terminal restriction fragment length polymorphism, cloning and sequencing of 16S rRNA showed that Clostridium cluster I and uncultured Peptococcaceae assimilated (13)CO(2) in the presence and absence of exogenous H(2), respectively. A similar experiment showed that Thermoanaerobacteriaceae and Acidobacteriaceae were dominant in the (13)C treatment at 50 °C. Assimilation of (13)CO(2) into archaeal rRNA was detected at 15 °C and 50 °C, mostly into Methanocellales, Methanobacteriales and rice cluster III. Acetoclastic methanogenic archaea were not detected. The above results showed the potential for acetogenesis in the presence and absence of exogenous H(2) at both 15 °C and 50 °C. However, syntrophic acetate oxidizers seemed to be only active at 50 °C, while other bacterial groups were active at 15 °C.

  10. 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.

  11. H2O2: A Dynamic Neuromodulator

    PubMed Central

    Rice, Margaret E.

    2012-01-01

    Increasing evidence implicates hydrogen peroxide (H2O2) as an intra- and intercellular signaling molecule that can influence processes from embryonic development to cell death. Most research has focused on relatively slow signaling, on the order of minutes to days, via second messenger cascades. However, H2O2 can also mediate subsecond signaling via ion channel activation. This rapid signaling has been examined most thoroughly in the nigrostriatal dopamine (DA) pathway, which plays a key role in facilitating movement mediated by the basal ganglia. In DA neurons of the substantia nigra, endogenously generated H2O2 activates ATP-sensitive K+ (KATP) channels that inhibit DA neuron firing. In the striatum, H2O2 generated downstream from glutamatergic AMPA receptor activation in medium spiny neurons acts as a diffusible messenger that inhibits axonal DA release, also via KATP channels. The source of dynamically generated H2O2 is mitochondrial respiration; thus, H2O2 provides a novel link between activity and metabolism via KATP channels. Additional targets of H2O2 include transient receptor potential (TRP) channels. In contrast to the inhibitory effect of H2O2 acting via KATP channels, TRP channel activation is excitatory. This review describes emerging roles of H2O2 as a signaling agent in the nigrostriatal pathway and other basal ganglia neurons. PMID:21666063

  12. H2O2: a dynamic neuromodulator.

    PubMed

    Rice, Margaret E

    2011-08-01

    Increasing evidence implicates hydrogen peroxide (H(2)O(2)) as an intracellular and intercellular signaling molecule that can influence processes from embryonic development to cell death. Most research has focused on relatively slow signaling, on the order of minutes to days, via second messenger cascades. However, H(2)O(2) can also mediate subsecond signaling via ion channel activation. This rapid signaling has been examined most thoroughly in the nigrostriatal dopamine (DA) pathway, which plays a key role in facilitating movement mediated by the basal ganglia. In DA neurons of the substantia nigra, endogenously generated H(2)O(2) activates ATP-sensitive K(+) (K-ATP) channels that inhibit DA neuron firing. In the striatum, H(2)O(2) generated downstream from glutamatergic AMPA receptor activation in medium spiny neurons acts as a diffusible messenger that inhibits axonal DA release, also via K-ATP channels. The source of dynamically generated H(2)O(2) is mitochondrial respiration; thus, H(2)O(2) provides a novel link between activity and metabolism via K-ATP channels. Additional targets of H(2)O(2) include transient receptor potential (TRP) channels. In contrast to the inhibitory effect of H(2)O(2) acting via K-ATP channels, TRP channel activation is excitatory. This review describes emerging roles of H(2)O(2) as a signaling agent in the nigrostriatal pathway and basal ganglia neurons.

  13. Pd immobilized on magnetic chitosan as a heterogeneous catalyst for acetalization and hydrogenation reactions

    NASA Astrophysics Data System (ADS)

    Zhou, Jinghui; Dong, Zhengping; Yang, Honglei; Shi, Zhiqiang; Zhou, Xingchun; Li, Rong

    2013-08-01

    A palladium-based catalyst supported on chitosan magnetite nanoparticles was successfully prepared by a facile one-pot template-free method combined with a metal adsorption-reduction procedure. The catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), vibrating sample magnetometer (VSM), X-ray powder detection (XRD), X-ray photoelectron spectroscopy (XPS). The catalyst afforded fast conversions for various aromatic nitro and unsaturated compounds, a under a H2 atmosphere in ethanol, even at room temperature. Furthermore, it was found that the catalyst showed a high activity for the acetalization reaction, affording over a 99% yield in all the cases investigated. Interestingly, the novel catalyst could be recovered in a facile manner from the reaction mixture and recycled five times without any significant loss in activity.

  14. 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.

  15. 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. PMID:7904712

  16. 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.

  17. 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.

  18. 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

  19. Progesterone, Inflammatory Cytokine (TNF-α), and Oxidative Stress (H2O2) Regulate Progesterone Receptor Membrane Component 1 Expression in Fetal Membrane Cells.

    PubMed

    Meng, Yan; Murtha, Amy P; Feng, Liping

    2016-09-01

    Progesterone receptor membrane component 1 (PGRMC1) is an important novel mediator of progesterone (P4) function in fetal membrane cells. We demonstrated previously that PGRMC1 is differentially expressed in fetal membranes among pregnancy subjects and diminished in preterm premature rupture of membrane subjects. In the current study, we aim to elucidate whether PGRMC1 expression is regulated by P4, tumor necrosis factor α (TNF-α), and H2O2 in fetal membrane cells. Primary cultured membrane cells were serum starved for 24 hours followed by treatments of P4, 17 hydroxyprogesterone caproate, and medroxyprogesterone 17 acetate (MPA) at 10(-7) mol/L with ethanol as vehicle control; TNF-α at 10, 20, and 50 ng/mL with phosphate-buffered saline (PBS) as control; and H2O2 at 10 and 100 μmol/L with culture media as control for 24, 48, and 72 hours. The messenger RNA (mRNA) and protein expression of PGRMC1 was quantified using polymerase chain reaction and Western blotting, respectively. We found that PGRMC1 protein expression was regulated by MPA, TNF-α, and H2O2 in a dose-dependent manner. This regulation is also specific to the type of cell (amnion, chorion, or decidua). The upregulation of PGRMC1 by MPA might be mediated through glucocorticoid receptor (GR) demonstrated using amnion and chorion cells model with GR knockdown by specific small interfering RNA transfection. The mRNA expression of PGRMC1 was decreased by H2O2 (100 μmol/L) treatment in amnion cells, which might ultimately result in downregulation of PGRMC1 protein as our data demonstrated. None of other treatments changed PGRMC1 mRNA level in these cells. We conclude that these stimuli act as regulatory factors of PGRMC1 in a cell-specific manner. PMID:26919974

  20. Alkaline biofiltration of H2S odors.

    PubMed

    González-Sánchez, Armando; Revah, Sergio; Deshusses, Marc A

    2008-10-01

    Hydrogen sulfide (H2S) is a very common odor nuisance which is best controlled by chemical or biological scrubbing. Under alkaline pH, the amount of H2S that can be solubilized in a scrubbing liquid increases significantly, and therefore, gas-liquid mass transfer limitations can be reduced. To date, biological scrubbing of H2S has been limited to neutral or acidic pH, despite the potential benefit of reduced mass transfer limitations at alkaline pH. In the present paper, an alkaliphilic sulfoxidizing bacterial consortium was deployed in a laboratory-scale biotrickling filter treating H2S at pH 10. The gas contact time ranged from 1 to 6 s, and H2S inlet concentrations, from 2.5 to 18 ppm(v). The results showed that under most conditions, H2S removal exceeded 98% and the degradation end-product was sulfate. At the highest H2S concentrations and shortest gas contacttimes, when the loading exceeded 30 g m(-3) h(-1), the H2S removal efficiency decreased significantly due to biological reaction limitation, and incompletely oxidized sulfides were measured in the trickling liquid. An analysis of the process demonstrated that operating the biotrickling filter at high pH results in an enhancement of the mass transfer by a factor of 1700-11 000. Overall, alkaline biotrickling filtration was shown to be very effective at low concentration of H2S and very short gas contact time. This is the first demonstration of a biotrickling filter for air pollution control operated at high pH.

  1. 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).

  2. Mechanisms of naturally evolved ethanol resistance in Drosophila melanogaster.

    PubMed

    Fry, James D

    2014-11-15

    The decaying fruit in which Drosophila melanogaster feed and breed can contain ethanol in concentrations as high as 6-7%. In this cosmopolitan species, populations from temperate regions are consistently more resistant to ethanol poisoning than populations from the tropics, but little is known about the physiological basis of this difference. I show that when exposed to low levels of ethanol vapor, flies from a tropical African population accumulated 2-3 times more internal ethanol than flies from a European population, giving evidence that faster ethanol catabolism by European flies contributes to the resistance difference. Using lines differing only in the origin of their third chromosome, however, I show that faster ethanol elimination cannot fully explain the resistance difference, because relative to African third chromosomes, European third chromosomes confer substantially higher ethanol resistance, while having little effect on internal ethanol concentrations. European third chromosomes also confer higher resistance to acetic acid, a metabolic product of ethanol, than African third chromosomes, suggesting that the higher ethanol resistance conferred by the former might be due to increased resistance to deleterious effects of ethanol-derived acetic acid. In support of this hypothesis, when ethanol catabolism was blocked with an Alcohol dehydrogenase mutant, there was no difference in ethanol resistance between flies with European and African third chromosomes. PMID:25392459

  3. Interstellar clouds containing optically thin H2

    NASA Technical Reports Server (NTRS)

    Jura, M.

    1975-01-01

    The theory of Black and Delgarno that the relative populations of the excited rotational levels of H2 can be understood in terms of cascading following absorption in the Lyman and Werner bands is employed to infer the gas densities and radiation fields within diffuse interstellar clouds containing H2 that is optically thin in those bands. The procedure is described for computing the populations of the different rotation levels, the relative distribution among the different rotation levels of newly formed H2 is determined on the basis of five simplified models, and the rate of H2 formation is estimated. The results are applied to delta Ori, two components of iota Ori, the second components of rho Leo and zeta Ori, tau Sco, gamma Vel, and zeta Pup. The inferred parameters are summarized for each cloud.

  4. 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.

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

    Atmospheric Science Data Center

    2015-02-06

    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 ...

  6. An H2A Histone Isotype, H2ac, Associates with Telomere and Maintains Telomere Integrity

    PubMed Central

    Tzeng, Tsai-Yu; Lin, I-Hsuan; Hsu, Ming-Ta

    2016-01-01

    Telomeres are capped at the ends of eukaryotic chromosomes and are composed of TTAGGG repeats bound to the shelterin complex. Here we report that a replication-dependent histone H2A isotype, H2ac, was associated with telomeres in human cells and co-immunoprecipitates with telomere repeat factor 2 (TRF2) and protection of telomeres protein 1 (POT1), whereas other histone H2A isotypes and mutations of H2ac did not bind to telomeres or these two proteins. The amino terminal basic domain of TRF2 was necessary for the association with H2ac and for the recruitment of H2ac to telomeres. Depletion of H2ac led to loss of telomeric repeat sequences, the appearance of dysfunctional telomeres, and chromosomal instability, including chromosomal breaks and anaphase bridges, as well as accumulation of telomere-associated DNA damage factors in H2ac depleted cells. Additionally, knockdown of H2ac elicits an ATM-dependent DNA damage response at telomeres and depletion of XPF protects telomeres against H2ac-deficiency-induced G-strand overhangs loss and DNA damage response, and prevents chromosomal instability. These findings suggest that the H2A isotype, H2ac, plays an essential role in maintaining telomere functional integrity. PMID:27228173

  7. 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.

  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. 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.

  10. 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.

  11. Isolation and Characterization of an H2-Oxidizing Thermophilic Methanogen

    PubMed Central

    Ferguson, Thomas J.; Mah, Robert A.

    1983-01-01

    A thermophilic methanogen was isolated from enrichment cultures originally inoculated with sludge from an anaerobic kelp digester (55°C). This isolate exhibited a temperature optimum of 55 to 60°C and a maximum near 70°C. Growth occurred throughout the pH range of 5.5 to 9.0, with optimal growth near pH 7.2. Although 4% salt was present in the isolation medium, salt was not required for optimal growth. The thermophile utilized formate or H2-CO2 but not acetate, methanol, or methylamines for growth and methanogenesis. Growth in complex medium was very rapid, and a minimum doubling time of 1.8 h was recorded in media supplemented with rumen fluid. Growth in defined media required the addition of acetate and an unknown factor(s) from digester supernatant, rumen fluid, or Trypticase. Cells in liquid culture were oval to coccoid, 0.7 to 1.8 μm in diameter, often occurring in pairs. The cells were easily lysed upon exposure to oxygen or 0.08 mg of sodium dodecyl sulfate per ml. The isolate was sensitive to tetracycline and chloramphenicol but not penicillin G or cycloserine. The DNA base composition was 59.69 mol% guanine plus cytosine. Images PMID:16346171

  12. 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.

  13. Nanostructured carbon-supported Pd electrocatalysts for ethanol oxidation: synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Gacutan, E. M.; Climaco, M. I.; Telan, G. J.; Malijan, F.; Hsu, H. Y.; Garcia, J.; Fulo, H.; Tongol, B. J.

    2012-12-01

    The need to lower the construction cost of fuel cells calls for the development of non-Pt based electrocatalysts. Among others, Pd has emerged as a promising alternative to Pt for fuel cell catalysis. This research aims to investigate the synthesis and characterization of nanostructured Pd-based catalysts dispersed on carbon support as anode materials in direct ethanol fuel cells. For the preparation of the first Pd-based electrocatalyst, palladium nanoparticles (NPs) were synthesized via oleylamine (OAm)-mediated synthesis and precursor method with a mean particle size of 3.63 ± 0.59 nm as revealed by transmission electron microscopy (TEM). Carbon black was used as a supporting matrix for the OAm-capped Pd NPs. Thermal annealing and acetic acid washing were used to remove the OAm capping agent. To evaluate the electrocatalytic activity of the prepared electrocatalyst towards ethanol oxidation, cyclic voltammetry (CV) studies were performed using 1.0 M ethanol in basic medium. The CV data revealed the highest peak current density of 11.05 mA cm-2 for the acetic acid-washed Pd/C electrocatalyst. Meanwhile, the fabrication of the second Pd-based electrocatalyst was done by functionalization of the carbon black support using 3:1 (v/v) H2SO4:HNO3. The metal oxide, NiO, was deposited using precipitation method while polyol method was used for the deposition of Pd NPs. X-ray diffraction (XRD) analysis revealed that the estimated particle size of the synthesized catalysts was at around 9.0-15.0 nm. CV results demonstrated a 36.7% increase in the catalytic activity of Pd-NiO/C (functionalized) catalyst towards ethanol oxidation compared to the non-functionalized catalyst.

  14. 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.

  15. Autoionizing np Rydberg states of H2

    NASA Astrophysics Data System (ADS)

    Xu, E. Y.; Helm, H.; Kachru, R.

    1989-04-01

    We report a study of the autoionizing np Rydberg states near the lowest ionization threshold of H2. Using resonant two-photon excitation, intermediate states in specific rotovibrational levels in the double well, E,F 1Σ+g states are prepared. Then, a second, tunable laser is used to photoionize via excitation of the np Rydberg states. Because of the stepwise laser excitation scheme employed in our experiment the photoionization occurs from states with vibrational wave functions very similar to those of the H+2 core. As a consequence, the autoionizing states appear as nearly symmetric resonances, rather than the highly asymmetric Beutler-Fano profiles observed from the direct photoexcitation from the ground state of H2. Our experiments show that the J=1 np states are broader than the J=3 np states converging to the same limit, suggesting that the two states autoionize into the ɛp and ɛf continuum, respectively. We compare our observations with a theoretical analysis using a multichannel quantum defect theory. The J=1 states reveal the profound effect caused by the perturbation of the autoionizing Rydberg series converging to the lowest vibrational and rotational state of H+2 by low-n states converging to higher vibrational states of the H2-ion core.

  16. Galactic H2O maser surveys

    NASA Astrophysics Data System (ADS)

    Felli, Marcello; Palagi, Francesco

    The first part is devoted to give an updated situation of the single dish surveys of galactic H2O masers, with particular emphasis on those associated with star forming regions (SFR). The main input for this comes from the updated Arcetri Atlas of H2O masers obtained with the Medicina 32m radio telescope. Available information on variability of the maser emission is also briefly reviewed. The second part gives a description of the results derived from the comparison of VLA observations of H2O masers in SFR and near IR images. J, H, K images are able to reveal the stellar cluster present in these highly obscured regions. IT is found that a stellar source with strong H-K excess is almost always associated with the maser spots (and not necessarily with an ultracompact HII region) and represents the direct evidence of the Young Stellar Object (YSO) which is required for the maser pumping. There are several indications suggesting that the H2O maser/near IR source may represent one of the earliest manifestation of a recently formed star. Finally, the importance of a coordination between near IR full sky surveys and H2O maser surveys is briefly discussed.

  17. Thermal modeling of NiH2 batteries

    NASA Technical Reports Server (NTRS)

    Ponthus, Agnes-Marie; Alexandre, Alain

    1994-01-01

    The following are discussed: NiH2 battery mission and environment; NiH2 cell heat dissipation; Nodal software; model development general philosophy; NiH2 battery model development; and NiH2 experimental developments.

  18. 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.

  19. H_2 Formation Mediated By PAHs

    NASA Astrophysics Data System (ADS)

    Pauzat, Francoise

    Although molecular hydrogen is the most abundant species in space, no satisfactory explanation for its formation in the interstellar medium has yet been proposed. It is usually assumed that H_2 is formed by recombination of H atoms adsorbed on grains which migrate from one site to another and react to form H_2. The energy released in the reaction is dissipated in the grain and used in the desorbtion process. However such a mechanism is not satisfying because the environment where H_2 is supposed to be formed is warm enough to easily desorb the H atoms, preventing them from reacting with each other. We present here the results of quantum mechanical calculations aimed at testing an alternative process in which an incident H atom is first chemisorbed on the grain before reacting with a peripheral chemically bonded H. To test such alternative, where the release of the H_2 molecule formed is insured by the exothermicity of the reaction, we had in the past, conducted preliminary studies at a semi-empirical level of theory. These investigations showed that an ionised compact PAH, as small as Pyrene, does fulfil the thermodynamical conditions to form H_2 through the reaction: PAH^+ + H -> dPAH^+ + H_2 where dPAH^+ stands for dehydrogenated positively charged PAH. Since regeneration of the original cation by addition of atomic hydrogen to the dehydrogenated positive ion is thermodynamically allowed, the process can be cycled. The feasability of such a process has been reconsidered using ab-initio methods of quantum chemistry for a better description of the full reaction path. The present study illustrates another possible role of PAHs. It suggests that positively charged species may be an important partner in the catalytic formation of molecular hydrogen.

  20. 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.

  1. Ethanol reassimilation and ethanol tolerance in Pitchia stipitis CBS 6054 as studied by [sup 13]C nuclear magnetic resonance spectroscopy

    SciTech Connect

    Skoog, K.; Hahn-Haegerdal, B. ); Degn, H.; Jacobsen, H.S.; Jacobsen, J.P. )

    1992-08-01

    Ethanol reassimilation in Pichia stipitis CBS 6054 was studied by using continuous cultures, and the oxidation of [1-[sup 13]C] ethanol was monitored by in vivo and in vitro [sup 13]C nuclear magnetic resonance spectroscopy. Acetate was formed when ethanol was reassimilated. The ATP/ADP ratio and the carbon dioxide production decreased, whereas the malate dehydrogenase activity increased, in ethanol-reassimilating cells. The results are discussed in terms of the low ethanol tolerance in P. stipitis compared with that in Saccharomyces cerevisiae.

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

    Atmospheric Science Data Center

    2015-01-30

    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 ...

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

    PubMed

    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. 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.

  5. 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.

  6. 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.

  7. 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...

  8. 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.

  9. 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...

  10. Constraining the ortho-to-para ratio of H2 with anomalous H_2CO absorption

    NASA Astrophysics Data System (ADS)

    Troscompt, N.; Faure, A.; Maret, S.; Ceccarelli, C.; Hily-Blant, P.; Wiesenfeld, L.

    2009-11-01

    Context: The ortho-to-para ratio (OPR) of molecular hydrogen is a fundamental parameter in understanding the physics and chemistry of molecular clouds. In dark and cold regions, however, H2 is not directly observable and the OPR of H2 in these sources has so far remained elusive. Aims: We show that the 6 cm absorption line of ortho-formaldehyde (H2CO) can be employed to constrain both the density and the OPR of H2 in dark clouds. Methods: Green Bank Telescope (GBT) observations of ortho-H2CO toward the molecular cloud Barnard 68 (B68) are reported. Non-LTE radiative transfer calculations combined with the well-constrained structure of B68 are then employed to derive the physical conditions in the absorption region. Results: We provide the first firm confirmation of the Townes & Cheung mechanism: propensity rules for the collisions of H2CO with H2 molecules are responsible for the sub-2.7 K cooling of the 6 cm doublet. Non-LTE calculations show that in the absorption region of B68, the kinetic temperature is ˜ 10 K, the ortho-H2CO column density amounts to ˜ 2.2× 1013 cm-2, the H2 density is in the range 1.4{-}2.4× 10 4 cm-3, and the OPR of H2 is close to zero. Our observations thus provide fresh evidence that H2 is mostly in its para form in the cold gas, as expected from theoretical considerations. Our results also suggest that formaldehyde absorption originates in the edge of B68, at visual extinctions A_V⪉ 0.5 mag. This work has been inspired by our colleague and friend Pierre Valiron, who passed away in August 2008. This paper is dedicated to his memory.

  11. Changes in the gene expression profile of Acetobacter aceti during growth on ethanol.

    PubMed

    Sakurai, Kenta; Arai, Hiroyuki; Ishii, Masaharu; Igarashi, Yasuo

    2012-03-01

    Acetobacter aceti NBRC 14818 shows a diauxic growth profile and temporarily accumulates acetate when grown in medium containing ethanol. However, the mechanisms underlying the metabolic switching between the incomplete oxidation of ethanol and overoxidation of acetate, and the control of stress resistance systems in A. aceti cells grown on ethanol are not fully understood. In this study, time-dependent transcriptome changes in cells during growth on ethanol were analyzed by DNA microarray. In A. aceti, ethanol is oxidized to acetate via acetaldehyde by sequential reactions of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). We found that the genes encoding pyrroloquinoline quinone-dependent ADH, membrane-bound ALDH, and two NAD(+)-ADHs were expressed constitutively in cells throughout the culture period. In contrast, the expression levels of genes encoding tricarboxylic acid (TCA) cycle enzymes were low during acetate accumulation until ethanol was consumed, but were significantly upregulated after the accumulated acetate was started to be consumed. This result suggests that changes in the carbon metabolic flow through the TCA cycle are important for the metabolic switching from acetate accumulation to the overoxidation of acetate. In addition, the genes for glyoxylate pathway enzymes were significantly upregulated soon after the cells began oxidizing ethanol, indicating that this pathway is important for the utilization of ethanol as a carbon source.

  12. 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.

  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. 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. L., III; Kulmala, M.

    2014-01-01

    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 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. Also the early growth process of the nucleated particles was not significantly influenced by the organic oxidation products in line with the expected growth by organic products using literature data. 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 ~107 molecule cm-3. Furthermore, the findings confirm the appearance of an additional oxidant for SO2 beside OH radicals, very likely stabilized Criegee Intermediates (sCI). A second set of experiments has been performed in the presence of added amines in the concentrations range of a few 107-1010 molecule cm-3 applying photolytic OH radical generation for H2SO4 production without addition of other organics. All amines showed significant nucleation enhancement with increasing efficiency in the order pyridine < aniline < dimethylamine < trimethylamine. This result supports the idea of H2SO4 cluster stabilization by

  15. 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.

  16. Double Photoionization of He and H2

    NASA Astrophysics Data System (ADS)

    Colgan, J.; Pindzola, M. S.; Robicheaux, F.

    2006-01-01

    Photoionization cross sections for both atomic helium and molecular hydrogen have recently been calculated using a time-dependent close-coupling method. The total electronic wavefunction for the two electron system is expanded in six dimensions, where four dimensions are represented on a radial and angular lattice and a coupled channels expansion is used to represent the other two dimensions. The double photoionization cross sections obtained for both He and H2 for a range of photon energies above the complete fragmentation threshold were compared with absolute experimental measurements. Very good agreement is found with experiment. Our method is also capable of being extended to calculations of single and triple differential cross sections of H2.

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

    SciTech Connect

    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.

  18. Substitution Reactions of the Aluminum Chlorogermylenoid H2GeClAlCl2 with HF, H2O, NH3, HCl, H2S, and PH3.

    PubMed

    Yan, Bingfei; Zhang, Mingxia; Li, Wenzuo; Xiao, Cuiping; Li, Qingzhong; Cheng, Jianbo

    2016-01-01

    Quantum chemical calculations have been performed for the substitution reactions of the aluminum chlorogermylenoid H2GeClAlCl2 with HF, H2O, NH3, HCl, H2S, and PH3 to get more insights into the reactivity of H2GeClAlCl2. The theoretical calculated results indicated that the substitution reactions of H2GeClAlCl2 with HF, H2O, NH3, HCl, H2S, and PH3 proceeded in a concerted manner. There were one transition state and one intermediate which connected the reactants and the products along the potential energy surface. The six substitution reactions of H2GeClAlCl2 with HF, H2O, NH3, HCl, H2S, and PH3 are compared with the addition reaction s of H2Ge with these hydrides. And based on the calculated results we concluded that the substitution reactions of H2GeClAlCl2 with these hydrides involve two steps, one is dissociation onto H2Ge with AlCl3, and the other is the addition reactions of H2Ge with HF, H2O, NH3, HCl, H2S, and PH3.

  19. Fluorescent excitation of interstellar H2

    NASA Technical Reports Server (NTRS)

    Black, John H.; Van Dishoeck, Ewine F.

    1987-01-01

    The infrared emission spectrum of H2 excited by ultraviolet absorption, followed by fluorescence, was investigated using comprehensive models of interstellar clouds for computing the spectrum and to assess the effects on the intensity to various cloud properties, such as density, size, temperature, and the intensity of the UV radiation field. It is shown that the absolute H2 IR line intensities depend primarily on the density of the cloud and the strength of the incident UV radiation, and to a much lesser exent on the temperature of the gas, the total thickness of the cloud, and the optical properties of the grains. A variety of recent observational results are discussed with reference to theoretical models. It is shown that the rich H2 emission spectrum of the reflection nebula NGC 2023 can be reproduced by a model with density of about 10,000/cu cm, temperature of about 80 K, and UV flux approximately 300 times that of the Galactic background starlight.

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

    PubMed Central

    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. PMID:25673654

  1. 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.

  2. 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. PMID:25673654

  3. 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.

  4. 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.

  5. 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.

  6. UV-spectrophotometric determination of alpha-tocopherol acetate in pharmaceutical preparations.

    PubMed

    Dahot, M U; Memon, M A; Memon, M A

    1990-01-01

    UV-spectrophotometric method has been developed to estimate alpha-tocopherol acetate in tablets and soft capsules. The lambdamax was found to be 285 nm in ethanol and isopropanol. The percentage error was found to be 2 to 7 in alpha-tocopherol acetate preparations whilst this increases in multivitamin preparations.

  7. Prostaglandins, H2-receptor antagonists and peptic ulcer disease.

    PubMed

    Bright-Asare, P; Habte, T; Yirgou, B; Benjamin, J

    1988-01-01

    Peptic ulcer develops when offensive factors overwhelm defensive processes in the gastroduodenal mucosa. Offensive factors include NSAIDs, hydrochloric acid-peptic activity, bile reflux, and some products of the lipoxygenase pathway such as leukotriene B4; whereas defensive processes are largely mediated by prostaglandins through poorly understood mechanisms uniformly termed cytoprotection. Cytoprotection, a physiological process working through the products of arachidonic acid metabolism, may result from the net effect of the protective actions of prostaglandins versus the damaging actions of leukotrienes. Some prostaglandins also have antisecretory effects. Therefore the peptic ulcer healing effects of prostaglandin analogues, all of which have significant antisecretory activity, may be more due to their antisecretory effects than primarily to their effects on mucosal defences. Certain drug-induced gastroduodenal lesions, e.g. NSAID-induced ulcers, which are often unresponsive to H2-receptor antagonists, have been healed and their recurrence prevented by the use of PGE1 and PGE2 analogues. All the prostaglandin analogues investigated to date in humans have the potential for inducing abortion, an important side effect which may limit their worldwide use. The optimal prostaglandin analogue for ulcer healing should not induce abortion and should be potently cytoprotective. The predominant damaging agent in the development of peptic ulcer disease is gastric hydrochloric acid. Thus, the worldwide established efficacy and safety of H2-receptor antagonists such as cimetidine, ranitidine, famotidine and most recently of roxatidine acetate suggest that these agents have become the standard by which other forms of anti-ulcer therapy should be judged. PMID:2905237

  8. The Key to Acetate: Metabolic Fluxes of Acetic Acid Bacteria under Cocoa Pulp Fermentation-Simulating Conditions

    PubMed Central

    Adler, Philipp; Frey, Lasse Jannis; Berger, Antje; Bolten, Christoph Josef; Hansen, Carl Erik

    2014-01-01

    Acetic acid bacteria (AAB) play an important role during cocoa fermentation, as their main product, acetate, is a major driver for the development of the desired cocoa flavors. Here, we investigated the specialized metabolism of these bacteria under cocoa pulp fermentation-simulating conditions. A carefully designed combination of parallel 13C isotope labeling experiments allowed the elucidation of intracellular fluxes in the complex environment of cocoa pulp, when lactate and ethanol were included as primary substrates among undefined ingredients. We demonstrate that AAB exhibit a functionally separated metabolism during coconsumption of two-carbon and three-carbon substrates. Acetate is almost exclusively derived from ethanol, while lactate serves for the formation of acetoin and biomass building blocks. Although this is suboptimal for cellular energetics, this allows maximized growth and conversion rates. The functional separation results from a lack of phosphoenolpyruvate carboxykinase and malic enzymes, typically present in bacteria to interconnect metabolism. In fact, gluconeogenesis is driven by pyruvate phosphate dikinase. Consequently, a balanced ratio of lactate and ethanol is important for the optimum performance of AAB. As lactate and ethanol are individually supplied by lactic acid bacteria and yeasts during the initial phase of cocoa fermentation, respectively, this underlines the importance of a well-balanced microbial consortium for a successful fermentation process. Indeed, AAB performed the best and produced the largest amounts of acetate in mixed culture experiments when lactic acid bacteria and yeasts were both present. PMID:24837393

  9. 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. PMID:26950756

  10. Quantum dynamics of proton migration in H2O dications: H2+ formation on ultrafast timescales.

    PubMed

    Garg, Manish; Tiwari, Ashwani K; Mathur, Deepak

    2012-01-14

    Irradiation of isolated water molecules by few-cycle pulses of intense infrared laser light can give rise to ultrafast rearrangement resulting in formation of the H(2) (+) ion. Such unimolecular reactions occur on the potential energy surface of the H(2)O(2+) dication that is accessed when peak laser intensities in the 10(15) W cm(-2) range and pulse durations as short as 9-10 fs are used; ion yields of ~1.5% relative to the H(2)O(+) ion are measured. We also study such reactions by means of time-dependent wavepacket dynamics on an ab initio potential energy surface of the dication and show that a proton, generated from O-H bond rupture, migrates towards the H-atom, and forms vibrationally excited H(2)(+) in a well-defined spatial zone.

  11. Wave-function inspired density functional applied to the H2/{{\\rm{H}}}_{2}^{+} challenge

    NASA Astrophysics Data System (ADS)

    Zhang, Igor Ying; Rinke, Patrick; Scheffler, Matthias

    2016-07-01

    We start from the Bethe–Goldstone equation (BGE) to derive a simple orbital-dependent correlation functional—BGE2—which terminates the BGE expansion at the second-order, but retains the self-consistent coupling of electron-pair correlations. We demonstrate that BGE2 is size consistent and one-electron ‘self-correlation’ free. The electron-pair correlation coupling ensures the correct H2 dissociation limit and gives a finite correlation energy for any system even if it has a no energy gap. BGE2 provides a good description of both H2 and {{{H}}}2+ dissociation, which is regarded as a great challenge in density functional theory (DFT). We illustrate the behavior of BGE2 analytically by considering H2 in a minimal basis. Our analysis shows that BGE2 captures essential features of the adiabatic connection path that current state-of-the-art DFT approximations do not.

  12. Acetate Utilization in Lactococcus lactis Deficient in Lactate Dehydrogenase: a Rescue Pathway for Maintaining Redox Balance

    PubMed Central

    Hols, Pascal; Ramos, Ana; Hugenholtz, Jeroen; Delcour, Jean; de Vos, Willem M.; Santos, Helena; Kleerebezem, Michiel

    1999-01-01

    Acetate was shown to improve glucose fermentation in Lactococcus lactis deficient in lactate dehydrogenase. 13C and 1H nuclear magnetic resonance studies using [2-13C]glucose and [2-13C]acetate as substrates demonstrated that acetate was exclusively converted to ethanol. This novel pathway provides an alternative route for NAD+ regeneration in the absence of lactate dehydrogenase. PMID:10464231

  13. 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.

  14. Vibrational dependence of the H2-H2 C6 dispersion coefficients.

    PubMed

    Hinde, Robert J

    2005-04-01

    We use the sum-over-states formalism to compute the imaginary-frequency dipole polarizabilities for H2, as a function of the H-H bond length, at the full configuration interaction level of theory using atom-centered d-aug-cc-pVQZ basis sets. From these polarizabilities, we obtain isotropic and anisotropic C6 dispersion coefficients for a pair of H2 molecules as functions of the two molecules' bond lengths.

  15. 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. PMID:25621533

  16. 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.

  17. 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

  18. Genetic organization of Acetobacter for acetic acid fermentation.

    PubMed

    Beppu, T

    Plasmid vectors for the acetic acid-producing strains of Acetobacter and Gluconobacter were constructed from their cryptic plasmids and the efficient transformation conditions were established. The systems allowed to reveal the genetic background of the strains used in the acetic acid fermentation. Genes encoding indispensable components in the acetic acid fermentation, such as alcohol dehydrogenase, aldehyde dehydrogenase and terminal oxidase, were cloned and characterized. Spontaneous mutations at high frequencies in the acetic acid bacteria to cause the deficiency in ethanol oxidation were analyzed. A new insertion sequence element, IS1380, was identified as a major factor of the genetic instability, which causes insertional inactivation of the gene encoding cytochrome c, an essential component of the functional alcohol dehydrogenase complex. Several genes including the citrate synthase gene of A. aceti were identified to confer acetic acid resistance, and the histidinolphosphate aminotransferase gene was cloned as a multicopy suppressor of an ethanol sensitive mutant. Improvement of the acetic acid productivity of an A. aceti strain was achieved through amplification of the aldehyde dehydrogenase gene with a multicopy vector. In addition, spheroplast fusion of the Acetobacter strains was developed and applied to improve their properties.

  19. 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.

  20. Molecular pathways underpinning ethanol-induced neurodegeneration

    PubMed Central

    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. PMID

  1. 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

  2. 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.

  3. Kinetic Energy Distribution of H(2p) Atoms from Dissociative Excitation of H2

    NASA Technical Reports Server (NTRS)

    Ajello, Joseph M.; Ahmed, Syed M.; Kanik, Isik; Multari, Rosalie

    1995-01-01

    The kinetic energy distribution of H(2p) atoms resulting from electron impact dissociation of H2 has been measured for the first time with uv spectroscopy. A high resolution uv spectrometer was used for the measurement of the H Lyman-alpha emission line profiles at 20 and 100 eV electron impact energies. Analysis of the deconvolved 100 eV line profile reveals the existence of a narrow line peak and a broad pedestal base. Slow H(2p) atoms with peak energy near 80 meV produce the peak profile, which is nearly independent of impact energy. The wings of H Lyman-alpha arise from dissociative excitation of a series of doubly excited Q(sub 1) and Q(sub 2) states, which define the core orbitals. The fast atom energy distribution peaks at 4 eV.

  4. Degradation of vinyl acetate by soil, sewage, sludge, and the newly isolated aerobic bacterium V2.

    PubMed Central

    Nieder, M; Sunarko, B; Meyer, O

    1990-01-01

    Vinyl acetate is subject to microbial degradation in the environment and by pure cultures. It was hydrolyzed by samples of soil, sludge, and sewage at rates of up to 6.38 and 1 mmol/h per g (dry weight) under aerobic and anaerobic conditions, respectively. Four yeasts and thirteen bacteria that feed aerobically on vinyl acetate were isolated. The pathway of vinyl acetate degradation was studied in bacterium V2. Vinyl acetate was degraded to acetate as follows: vinyl acetate + NAD(P)+----2 acetate + NAD(P)H + H+. The acetate was then converted to acetyl coenzyme A and oxidized through the tricarboxylic acid cycle and the glyoxylate bypass. The key enzyme of the pathway is vinyl acetate esterase, which hydrolyzed the ester to acetate and vinyl alcohol. The latter isomerized spontaneously to acetaldehyde and was then converted to acetate. The acetaldehyde was disproportionated into ethanol and acetate. The enzymes involved in the metabolism of vinyl acetate were studied in extracts. Vinyl acetate esterase (Km = 6.13 mM) was also active with indoxyl acetate (Km = 0.98 mM), providing the basis for a convenient spectrophotometric test. Substrates of aldehyde dehydrogenase were formaldehyde, acetaldehyde, propionaldehyde, and butyraldehyde. The enzyme was equally active with NAD+ or NADP+. Alcohol dehydrogenase was active with ethanol (Km = 0.24 mM), 1-propanol (Km = 0.34 mM), and 1-butanol (Km = 0.16 mM) and was linked to NAD+. The molecular sizes of aldehyde dehydrogenase and alcohol dehydrogenase were 145 and 215 kilodaltons, respectively. PMID:2285314

  5. 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!!!

  6. Matrix-isolation and computational study of H2CCCl and H2CCBr radicals.

    PubMed

    Zhu, Cheng; Duarte, Luís; Khriachtchev, Leonid

    2016-08-21

    We report on two new radicals, H2CCCl and H2CCBr, prepared in low-temperature noble-gas matrices and characterized using infrared spectroscopy. These radicals are made by UV photolysis of HCCCl and HCCBr and subsequent thermal annealing to mobilize hydrogen atoms in the matrices and promote their reaction with the residual precursor molecules. Three characteristic infrared bands are observed for each radical. The assignments are supported by quantum chemical calculations at the B3LYP and CCSD(T) levels of theory with the def2-TZVPPD basis set. PMID:27544110

  7. Matrix-isolation and computational study of H2CCCl and H2CCBr radicals

    NASA Astrophysics Data System (ADS)

    Zhu, Cheng; Duarte, Luís; Khriachtchev, Leonid

    2016-08-01

    We report on two new radicals, H2CCCl and H2CCBr, prepared in low-temperature noble-gas matrices and characterized using infrared spectroscopy. These radicals are made by UV photolysis of HCCCl and HCCBr and subsequent thermal annealing to mobilize hydrogen atoms in the matrices and promote their reaction with the residual precursor molecules. Three characteristic infrared bands are observed for each radical. The assignments are supported by quantum chemical calculations at the B3LYP and CCSD(T) levels of theory with the def2-TZVPPD basis set.

  8. Hydrogen atom abstraction from aldehydes - OH + H2CO and O + H2CO

    NASA Technical Reports Server (NTRS)

    Dupuis, M.; Lester, W. A., Jr.

    1984-01-01

    The essential features of the potential energy surfaces governing hydrogen abstraction from formaldehyde by oxygen atom and hydroxyl radical have been characterized with ab inito multiconfiguration Hartree-Fock (MCHF) and configuration interaction (CI) wave functions. The results are consistent with a very small activation energy for the OH + H2CO reaction, and an activation energy of a few kcal/mol for the O + H2CO reaction. In the transition state structure of both systems, the attacking oxygen atom is nearly collinear with the attacked CH bond.

  9. Ionothermal synthesis of homochiral framework with acetate-pillared cobalt-camphorate architecture.

    PubMed

    Chen, Shumei; Zhang, Jian; Bu, Xianhui

    2008-07-01

    A new organically templated homochiral material (EMIm)[Co 2( d-cam) 2(ac)] ( 1; d-H 2cam = d-camphoric acid; ac = acetate; EMIm = 1-ethyl-3-methylimidazolium) has been ionothermally synthesized, and it features an unusual acetate-pillared cobalt-camphorate architecture encapsulating the cationic component of the ionic liquid.

  10. 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

    2016-01-01

    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. PMID:27007358

  11. Isolation and characterization of a hydrogen- and ethanol-producing Clostridium sp. strain URNW.

    PubMed

    Ramachandran, Umesh; Wrana, Nathan; Cicek, Nazim; Sparling, Richard; Levin, David B

    2011-03-01

    Identification, characterization, and end-product synthesis patterns were analyzed in a newly identified mesophilic, anaerobic Clostridium sp. strain URNW, capable of producing hydrogen (H₂) and ethanol. Metabolic profiling was used to characterize putative end-product synthesis pathways of the Clostridium sp. strain URNW, which was found to grow on cellobiose; on hexose sugars, such as glucose, sucrose, and mannose; and on sugar alcohols, like mannitol and sorbitol. When grown in batch cultures on 2 g cellobiose·L⁻¹, Clostridium sp. strain URNW showed a cell generation time of 1.5 h, and the major end-products were H2, formate, carbon dioxide (CO₂), lactate, butyrate, acetate, pyruvate, and ethanol. The total volumetric H₂ production was 14.2 mmol·(L culture)⁻¹ and the total production of ethanol was 0.4 mmol·(L culture)⁻¹. The maximum yield of H₂ was 1.3 mol·(mol glucose equivalent)⁻¹ at a carbon recovery of 94%. The specific production rates of H₂, CO₂, and ethanol were 0.45, 0.13, and 0.003 mol·h⁻¹·(g dry cell mass)-1, respectively. BLAST analyses of 16S rDNA and chaperonin 60 (cpn60) sequences from Clostridium sp. strain URNW revealed a 98% nucleotide sequence identity with the 16S rDNA and cpn60 sequences from Clostridium intestinale ATCC 49213. Phylogenetic analyses placed Clostridium sp. strain URNW within the butyrate-synthesizing clostridia.

  12. 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.

  13. 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.

  14. Pharmacology of JB-9315, a new selective histamine H2-receptor antagonist.

    PubMed

    Palacios, B; Montero, M J; Sevilla, M A; San Román, L

    1998-02-01

    1. The histamine H2-receptor antagonistic activity and antisecretory and antiulcer effects of JB-9315 were studied in comparison with the standard H2 blocker ranitidine. 2. In vitro, JB-9315 is a competitive antagonist of histamine H2 receptors in the isolated, spontaneously beating guinea-pig right atrium, with a pA2 value of 7.30 relative to a value of 7.36 for ranitidine. JB-9315 was specific for the histamine H2 receptor because, at high concentration, it did not affect histamine- or acetylcholine-induced contractions in guinea-pig isolated ileum or rat isolated duodenum, respectively. 3. JB-9315 dose dependently inhibited histamine-, pentagastrin- or carbachol-stimulated acid secretion and basal secretion in the perfused stomach preparation of the anesthetized rat. In the pylorus-ligated rat after intraperitoneal administration, total acid output over 4 h was inhibited by JB-9315 with an ID50 of 32.8 mg/kg, confirming its H2-receptor antagonist properties. 4. JB-9315 showed antiulcer activity against cold stress plus indomethacin-induced lesions with an ID50 of 6.8 mg/kg. 5. JB-9315, 50 and 100 mg/kg, inhibited macroscopic gastric hemorrhagic lesions induced by ethanol. In contrast, ranitidine (50 mg/kg) failed to reduce these lesions. 6. These results indicate that JB-9315 is a new antiulcer drug that exerts a cytoprotective effect in addition to its gastric antisecretory activity.

  15. 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.

  16. Distribution of ethanol between saliva and blood in man.

    PubMed

    Jones, A W

    1979-01-01

    1. Forty-eight male subjects drank ethanol (0.72 g/kg) as neat whisky on a fasting stomach within 20 min and the ethanol concentrations in saliva and capillary blood were determined at 30--60 min intervals for the next 7 h. 2. The concentration of ethanol in saliva was generally slightly higher than in capillary blood, as expected from their relative water contents. The mean saliva/blood ethanol ratio between 60 and 360 min from the start of drinking was 1.082 (s.e.m. = 0.0059), (n = 336). Moreover, the saliva/blood ethanol ratio was remarkably constant throughout the absorption, distribution and elimination phases of ethanol metabolism. 3. The saliva (y) and blood ethanol (x) concentrations (mmol/l) were highly correlated (r = 0.976, standard error = 0.011, P less than 0.001). The regression equation was y = 0.109 + 1.071x. The saliva and blood ethanol concentrations reached zero nearly simultaneously, there being no appreciable time lag in the saliva. 4. The results indicate that saliva is a practical medium for ethanol determinations and that blood ethanol can be reliably estimated from analysis of a saliva specimen. Saliva ethanol analysis could well serve as supporting evidence in clinical and medico-legal diagnosis of ethanol intoxication.

  17. Synthesis of zinc sulfide nanoparticles during zinc oxidization by H2S and H2S/H2O supercritical fluids

    NASA Astrophysics Data System (ADS)

    Vostrikov, A. A.; Fedyaeva, O. N.; Sokol, M. Ya.; Shatrova, A. V.

    2014-12-01

    Formation of zinc sulfide nanoparticles was detected during interaction of bulk samples with hydrogen sulfide at supercritical parameters. Synthesis proceeds with liberation of H2 by the reaction nZn + nH2S = (ZnS) n + nH2. It has been found by the X-ray diffraction method, scanning electron microscopy, and mass spectrometry that the addition of water stimulates coupled reactions of nanoparticle synthesis nZn + nH2O = (ZnO) n + nH2 and (ZnO) n + nH2S = (ZnS) n + nH2O and brings about an increase in the synthesis rate and morphological changes of (ZnS) n nanoparticles.

  18. Acclimation to hypoxia in Chlamydomonas reinhardtii: can biophotolysis be the major trigger for long-term H2 production?

    PubMed

    Scoma, Alberto; Durante, Lorenzo; Bertin, Lorenzo; Fava, Fabio

    2014-12-01

    In anaerobiosis, the microalga Chlamydomonas reinhardtii is able to produce H2 gas. Electrons mainly derive from mobilization of internal reserves or from water through biophotolysis. However, the exact mechanisms triggering this process are still unclear. Our hypothesis was that, once a proper redox state has been achieved, H2 production is eventually observed. To avoid nutrient depletion, which would result in enhanced fermentative pathways, we aimed to induce long-lasting H2 production solely through a photosynthesis : respiration equilibrium. Thus, growing cells were incubated in Tris Acetate Phosphate (TAP) medium under low light and high chlorophyll content. After a 250-h acclimation phase, a 350-h H2 production phase was observed. The light-to-H2 conversion efficiency was comparable to that given in some reports operating under sulphur starvation. Electron sources were found to be water, through biophotolysis, and proteins, particularly through photofermentation. Nonetheless, a substantial contribution from acetate could not be ruled out. In addition, photosystem II (PSII) inhibition by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) showed that it actively contributed to maintaining a redox balance during cell acclimation. In appropriate conditions, PSII may represent the major source of reducing power to feed the H2 evolution process, by inducing and maintaining an ideal excess of reducing power. PMID:25103459

  19. Biological production of ethanol from coal

    SciTech Connect

    Not Available

    1989-01-01

    Two batch and one continuous reactor study involving Clostridium ljungdahlii were carried out. First, the effects of H{sub 2} partial pressure on growth, CO and H{sub 2} uptake and product formation by C. ljungdahlii were investigated in batch culture. Over the concentration range studied, it was observed that CO was preferentially utilized in favor of H{sub 2}. It was also seen that increasing H{sub 2} partial pressures increased the ratio of ethanol to acetate. Finally, a two-stage CSTR system was successfully operated with C. ljungdahlii in which growth occurred in the first stage and ethanol production occurred in the second stage.

  20. 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

  1. 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.

  2. Thermophysical Properties of Fluid H2O

    NASA Astrophysics Data System (ADS)

    Kestin, J.; Sengers, J. V.; Kamgar-Parsi, B.; Sengers, J. M. H. Levelt

    1984-01-01

    In view of the important role that water substance plays in science and industry, this paper lists the thermophysical properties of fluid H2O which are most needed for engineering applications. The properties are described in a very compact form with the aid of explicit expressions for programing on a computer and for inclusion in data banks. The paper includes a fundamental equation in the form of the Helmholtz free energy expressed as an analytic function of temperature and density. This fundamental equation is a dimensionless version of the Provisional IAPS Formulation 1982 for the Thermodynamic Properties of Ordinary Water Substance for Scientific and General Use, which enables one to calculate all equilibrium thermodynamic properties in a wide range of states, but with the exclusion of a small region near the critical point. In the latter region, the equilibrium properties are described by a scaled fundamental equation in the form of the pressure as a function of chemical potential and temperature. In addition, the paper gives equations for the viscosity, thermal conductivity, and surface tension. All equations in the paper are mutually thermodynamically consistent. The set of equations and their constants listed here represents the most reliable information according to the judgment of the authors.

  3. H2 arcjet performance mapping program

    NASA Technical Reports Server (NTRS)

    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.

  4. 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

    2015-01-01

    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. PMID:26437775

  5. Acetobacter aceti possesses a proton motive force-dependent efflux system for acetic acid.

    PubMed

    Matsushita, Kazunobu; Inoue, Taketo; Adachi, Osao; Toyama, Hirohide

    2005-07-01

    Acetic acid bacteria are obligate aerobes able to oxidize ethanol, sugar alcohols, and sugars into their corresponding acids. Among them, Acetobacter and Gluconacetobacter species have very high ethanol oxidation capacity, leading to accumulation of vast amounts of acetic acid outside the cell. Since these bacteria are able to grow in media with high concentrations of acetic acid, they must possess a specific mechanism such as an efflux pump by which they can resist the toxic effects of acetic acid. In this study, the efflux pump of Acetobacter aceti IFO 3283 was examined using intact cells and membrane vesicles. The accumulation of acetic acid/acetate in intact cells was increased by the addition of a proton uncoupler and/or cyanide, suggesting the presence of an energy-dependent efflux system. To confirm this, right-side-out and inside-out membrane vesicles were prepared from A. aceti IFO 3283, and the accumulation of acetic acid/acetate in the vesicles was examined. Upon the addition of a respiratory substrate, the accumulation of acetic acid/acetate in the right-side-out vesicles was largely decreased, while its accumulation was very much increased in the inside-out vesicles. These respiration-dependent phenomena observed in both types of membrane vesicles were all sensitive to a proton uncoupler. Acetic acid/acetate uptake in the inside-out membrane vesicles was dependent not on ATP but on the proton motive force. Furthermore, uptake was shown to be rather specific for acetic acid and to be pH dependent, because higher uptake was observed at lower pH. Thus, A. aceti IFO 3283 possesses a proton motive force-dependent efflux pump for acetic acid.

  6. 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.

  7. 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.

  8. Methane from acetate.

    PubMed

    Ferry, J G

    1992-09-01

    The general features are known for the pathway by which most methane is produced in nature. All acetate-utilizing methanogenic microorganisms contain CODH which catalyzes the cleavage of acetyl-CoA; however, the pathway differs from all other acetate-utilizing anaerobes in that the methyl group is reduced to methane with electrons derived from oxidation of the carbonyl group of acetyl-CoA to CO2. The current understanding of the methanogenic fermentation of acetate provides impressions of nature's novel solutions to problems of methyl transfer, electron transport, and energy conservation. The pathway is now at a level of understanding that will permit productive investigations of these and other interesting questions in the near future. PMID:1512186

  9. Increased brain uptake and oxidation of acetate in heavy drinkers.

    PubMed

    Jiang, Lihong; Gulanski, Barbara Irene; De Feyter, Henk M; Weinzimer, Stuart A; Pittman, Brian; Guidone, Elizabeth; Koretski, Julia; Harman, Susan; Petrakis, Ismene L; Krystal, John H; Mason, Graeme F

    2013-04-01

    When a person consumes ethanol, the body quickly begins to convert it to acetic acid, which circulates in the blood and can serve as a source of energy for the brain and other organs. This study used 13C magnetic resonance spectroscopy to test whether chronic heavy drinking is associated with greater brain uptake and oxidation of acetic acid, providing a potential metabolic reward or adenosinergic effect as a consequence of drinking. Seven heavy drinkers, who regularly consumed at least 8 drinks per week and at least 4 drinks per day at least once per week, and 7 light drinkers, who consumed fewer than 2 drinks per week were recruited. The subjects were administered [2-13C]acetate for 2 hours and scanned throughout that time with magnetic resonance spectroscopy of the brain to observe natural 13C abundance of N-acetylaspartate (NAA) and the appearance of 13C-labeled glutamate, glutamine, and acetate. Heavy drinkers had approximately 2-fold more brain acetate relative to blood and twice as much labeled glutamate and glutamine. The results show that acetate transport and oxidation are faster in heavy drinkers compared with that in light drinkers. Our finding suggests that a new therapeutic approach to supply acetate during alcohol detoxification may be beneficial. PMID:23478412

  10. 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.

  11. Carbon Isotope Fractionation of 11 Acetogenic Strains Grown on H2 and CO2

    PubMed Central

    Dreisbach, Lisa K.; Conrad, Ralf

    2013-01-01

    Acetogenic bacteria are able to grow autotrophically on hydrogen and carbon dioxide by using the acetyl coenzyme A (acetyl-CoA) pathway. Acetate is the end product of this reaction. In contrast to the fermentative route of acetate production, which shows almost no fractionation of carbon isotopes, the acetyl-CoA pathway has been reported to exhibit a preference for light carbon. In Acetobacterium woodii the isotope fractionation factor (ε) for 13C and 12C has previously been reported to be ε = −58.6‰. To investigate whether such a strong fractionation is a general feature of acetogenic bacteria, we measured the stable carbon isotope fractionation factor of 10 acetogenic strains grown on H2 and CO2. The average fractionation factor was εTIC = −57.2‰ for utilization of total inorganic carbon and εacetate = −54.6‰ for the production of acetate. The strongest fractionation was found for Sporomusa sphaeroides (εTIC = −68.3‰), the lowest fractionation for Morella thermoacetica (εTIC = −38.2‰). To investigate the reproducibility of our measurements, we determined the fractionation factor of 21 biological replicates of Thermoanaerobacter kivui. In general, our study confirmed the strong fractionation of stable carbon during chemolithotrophic acetate formation in acetogenic bacteria. However, the specific characteristics of the bacterial strain, as well as the cultural conditions, may have a moderate influence on the overall fractionation. PMID:23275504

  12. [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.

  13. Ethanol cytotoxic effect on trophoblast cells.

    PubMed

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

    2014-03-01

    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.

  14. 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

  15. Core-mass nonadiabatic corrections to molecules: H2, H2+, and isotopologues.

    PubMed

    Diniz, Leonardo G; Alijah, Alexander; Mohallem, José Rachid

    2012-10-28

    For high-precision calculations of rovibrational states of light molecules, it is essential to include non-adiabatic corrections. In the absence of crossings of potential energy surfaces, they can be incorporated in a single surface picture through coordinate-dependent vibrational and rotational reduced masses. We present a compact method for their evaluation and relate in particular the vibrational mass to a well defined nuclear core mass derived from a Mulliken analysis of the electronic density. For the rotational mass we propose a simple, but very effective parametrization. The use of these masses in the nuclear Schrödinger equation yields numerical data for the corrections of a much higher quality than can be obtained with optimized constant masses, typically better than 0.1 cm(-1). We demonstrate the method for H(2), H(2)(+), and singly deuterated isotopologues. Isotopic asymmetry does not present any particular difficulty. Generalization to polyatomic molecules is straightforward. PMID:23126719

  16. Core-mass nonadiabatic corrections to molecules: H2, H2+, and isotopologues

    NASA Astrophysics Data System (ADS)

    Diniz, Leonardo G.; Alijah, Alexander; Mohallem, José Rachid

    2012-10-01

    For high-precision calculations of rovibrational states of light molecules, it is essential to include non-adiabatic corrections. In the absence of crossings of potential energy surfaces, they can be incorporated in a single surface picture through coordinate-dependent vibrational and rotational reduced masses. We present a compact method for their evaluation and relate in particular the vibrational mass to a well defined nuclear core mass derived from a Mulliken analysis of the electronic density. For the rotational mass we propose a simple, but very effective parametrization. The use of these masses in the nuclear Schrödinger equation yields numerical data for the corrections of a much higher quality than can be obtained with optimized constant masses, typically better than 0.1 cm^{-1}. We demonstrate the method for H_2, H_2^+, and singly deuterated isotopologues. Isotopic asymmetry does not present any particular difficulty. Generalization to polyatomic molecules is straightforward.

  17. 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.

  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. PMID:26253254

  19. 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.

  20. Role of the glyoxylate pathway in acetic acid production by Acetobacter aceti.

    PubMed

    Sakurai, Kenta; Yamazaki, Shoko; Ishii, Masaharu; Igarashi, Yasuo; Arai, Hiroyuki

    2013-01-01

    Wild-type Acetobacter aceti NBRC 14818 possesses genes encoding isocitrate lyase (aceA) and malate synthase (glcB), which constitute the glyoxylate pathway. In contrast, several acetic acid bacteria that are utilized for vinegar production lack these genes. Here, an aceA-glcB knockout mutant of NBRC 14818 was constructed and used for investigating the role of the glyoxylate pathway in acetate productivity. In medium containing ethanol as a carbon source, the mutant grew normally during ethanol oxidation to acetate, but exhibited slower growth than that of the wild-type strain as the accumulated acetate was oxidized. The mutant grew similarly to that of the wild-type strain in medium containing glucose as a carbon source, indicating that the glyoxylate pathway was not necessary for glucose utilization. However, in medium containing both ethanol and glucose, the mutant exhibited significantly poorer growth and lower glucose consumption compared to the wild-type strain. Notably, the mutant oxidized ethanol nearly stoichiometrically to acetate, which was retained in the medium for a longer period of time than the acetate produced by wild-type strain. The features of the aceA-glcB knockout mutant revealed here indicate that the lack of the glyoxylate pathway is advantageous for industrial vinegar production by A. aceti.

  1. A molecular hybrid of the H-2Dd and H-2Ld genes expressed in the dm1 mutant.

    PubMed Central

    Burnside, S S; Hunt, P; Ozato, K; Sears, D W

    1984-01-01

    Sequential immunoprecipitates show that H-2dm1 mutant cells express a hybrid "H-2D/L" antigen exhibiting determinants normally associated with two different gene products of the parental d haplotype-i.e., the H-2Dd and H-2Ld antigens. The hybrid H-2D/Ldm1 antigen appears to consist of a portion of the NH2-terminal extracellular half of the H-2Dd antigen "fused" to a portion of the COOH-terminal extracellular half of the H-2Ld antigen. This structure is inferred from the reactivity of dm1 antigens with cytotoxic T lymphocytes specific for H-2Ld determinants and with monoclonal antibodies specific for determinants in the structural domains of H-2Ld or H-2Dd. The H-2D/Ldm1 molecule apparently retains all of the third external domain (C2 or alpha 3) and part of the second external domain (C1 or alpha 2) of H-2Ld, but its first external domain (N or alpha 1) derives from H-2Dd. From these findings and from previous peptide mapping studies, we propose that the H-2D/Ldm1 antigen is the product of a hybrid gene that has resulted from an unequal crossover between the parental H-2Dd and H-2Ld genes, leaving the N exon and part of the C1 exon of the H-2Dd gene joined to the H-2Ld gene beginning somewhere within its C1 exon. PMID:6206494

  2. Influence of H(2) and O(2) on sulphate-reducing activity of a subterranean community and the coupled response in redox potential.

    PubMed

    Pedersen, Karsten

    2012-12-01

    Deep Fennoscandian groundwater is anaerobic, reducing in character and populated by a large diversity of obligate and facultative anaerobic microorganisms. Concentrations of H(2) and carbon monoxide are often 0.01-1 μM and of dissolved organic carbon (DOC) and methane 0.01-1 mM. Microbial activity involving these electron and energy donors may help keep deep groundwater anaerobic and reduced. H(2) was added in concentrations of 0.1-10 mM to a sulphate-reducing community attached to crushed rock in groundwater under a pressure of 2.0 MPa and in situ geochemical conditions. Experiments reported a threshold concentration of approximately 1 μM H(2) at which sulphate reduction ceased, despite the presence of DOC and acetate, suggesting that H(2) was needed for sulphate-reducing activity. δ(13)C values of acetate and DOC data suggested that organic material was degraded to acetate by means of a heterotrophic process. New pressure-resistant micro-sensors for measuring E(h) indicated an H(2)-concentration-dependent decrease in E(h). The investigated community rapidly mitigated the increase in E(h) caused by repeated additions of 0.1-0.2 mM pulses of O(2) as long as H(2) was available. The results imply that sulphate reduction to sulphide with H(2) may dominate sulphate-rich groundwater, which may have implications for metallic underground constructions.

  3. 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

  4. 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.

  5. Protein content and enzyme activities in methanol- and acetate-grown Methanosarcina thermophila.

    PubMed Central

    Jablonski, P E; DiMarco, A A; Bobik, T A; Cabell, M C; Ferry, J G

    1990-01-01

    The cell extract protein content of acetate- and methanol-grown Methanosarcina thermophila TM-1 was examined by two-dimensional polyacrylamide gel electrophoresis. More than 100 mutually exclusive spots were present in acetate- and methanol-grown cells. Spots corresponding to acetate kinase, phosphotransacetylase, and the five subunits of the carbon monoxide dehydrogenase complex were identified in acetate-grown cells. Activities of formylmethanofuran dehydrogenase, formylmethanofuran:tetrahydromethanopterin formyltransferase, 5,10-methenyltetrahydromethanopterin cyclohydrolase, methylene tetrahydromethanopterin:coenzyme F420 oxidoreductase, formate dehydrogenase, and carbonic anhydrase were examined in acetate- and methanol-grown Methanosarcina thermophila. Levels of formyltransferase in either acetate- or methanol-grown Methanosarcina thermophila were approximately half the levels detected in H2-CO2-grown Methanobacterium thermoautotrophicum. All other enzyme activities were significantly lower in acetate- and methanol-grown Methanosarcina thermophila. Images FIG. 1 FIG. 2 PMID:2307649

  6. 45 CFR 1626.11 - H-2 agricultural workers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false H-2 agricultural workers. 1626.11 Section 1626.11... ON LEGAL ASSISTANCE TO ALIENS § 1626.11 H-2 agricultural workers. (a) Nonimmigrant agricultural workers admitted under the provisions of 8 U.S.C. 1101(a)(15)(h)(ii), commonly called H-2 workers, may...

  7. [Pharmacokinetics, metabolism, and analytical methods of ethanol].

    PubMed

    Goullé, J-P; Guerbet, M

    2015-09-01

    Alcohol is a licit substance whose significant consumption is responsible for a major public health problem. Every year, a large number of deaths are related to its consumption. It is also involved in various accidents, on the road, at work, as well as during acts of violence. Ethanol absorption and its fate are detailed. It is mainly absorbed in the small intestine. It accompanies the movements of the water, so it diffuses in all the tissues uniformly with the exception of bones and fat. The major route of ethanol detoxification is located into the liver. Detoxification is a saturable two-step oxidation. During the first stage ethanol is oxidized into acetaldehyde, under the action of alcohol dehydrogenase. During the second stage acetaldehyde is oxidized into acetate. Genetic factors or some drugs are able to disturb the absorption and the metabolism of ethanol. The analytical methods for the quantification of alcohol in man include analysis in exhaled air and in blood. The screening and quantification of ethanol for road safety are performed in exhaled air. In hospitals, blood ethanol determination is routinely performed by enzymatic method, but the rule for forensic samples is gas chromatography.

  8. Detection of HF Toward PKS 1830–211, Search for Interstellar H2F+, and Laboratory Study of H2F+ and H2Cl+ Dissociative Recombination

    NASA Astrophysics Data System (ADS)

    Kawaguchi, K.; Muller, S.; Black, J. H.; Amano, T.; Matsushima, F.; Fujimori, R.; Okabayahsi, Y.; Nagahiro, H.; Miyamoto, Y.; Tang, J.

    2016-05-01

    We report extragalactic observations of two fluorine-bearing species, hydrogen fluoride (HF) and fluoronium (H2F+), in the z = 0.89 absorber in front of the lensed blazar PKS 1830‑211 with the Atacama Large Millimeter/submillimeter Array. HF was detected toward both southwest and northeast images of the blazar, with column densities >3.4 × 1014 cm‑2 and 0.18 × 1014 cm‑2, respectively. H2F+ was not detected, down to an upper limit (3σ) of 8.8 × 1011 cm‑2 and an abundance ratio of [H2F+]/[HF] ≤slant 1/386. We also searched for H2F+ toward the Galactic sources NGC 6334 I and W51C, and toward Galactic center clouds with the Herschel HIFI spectrometer.6 The upper limit on the column density was derived to be 2.5 × 1011 cm‑2 in NGC 6334 I, which is 1/68 of that for H2Cl+. In constrast, the ortho transition of H2Cl+ is detected toward PKS 1830–211. To understand the small abundance of interstellar H2F+, we carried out laboratory experiments to determine the rate constants for the ion–electron recombination reaction by infrared time-resolved spectroscopy. The constants determined are k e (209 K) = (1.1+/- 0.3)× {10}-7 cm3 s‑1 and (0.46+/- 0.05)× {10}-7 cm3 s‑1 for H2F+ and H2Cl+, respectively. The difference in the dissociative recombination rates between H2F+ and H2Cl+ by a factor ˜2 and the cosmic abundance ratio [F]/[Cl] ≈ 1/6 are not enough to explain the much smaller abundance of H2F+. The difference in the formation mechanism of H2F+ and H2Cl+ in interstellar space would be a major factor in the small abundance of H2F+.

  9. 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

  10. 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. PMID:25280112

  11. 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.

  12. Sulfide oxidation and nitrate reduction for potential mitigation of H2S in landfills.

    PubMed

    Fang, Yuan; Du, Yao; Feng, Huan; Hu, Li-Fang; Shen, Dong-Sheng; Long, Yu-Yang

    2015-04-01

    Because H2S emitted by landfill sites has seriously endangered human health, its removal is urgent. H2S removal by use of an autotrophic denitrification landfill biocover has been reported. In this process, nitrate-reducing and sulfide-oxidizing bacteria use a reduced sulfur source as electron donor when reducing nitrate to nitrogen gas and oxidizing sulfur compounds to sulfate. The research presented here was performed to investigate the possibility of endogenous mitigation of H2S by autotrophic denitrification of landfill waste. The sulfide oxidation bioprocess accompanied by nitrate reduction was observed in batch tests inoculated with mineralized refuse from a landfill site. Repeated supply of nitrate resulted in rapid oxidation of the sulfide, indicating that, to a substantial extent, the bioprocess may be driven by functional microbes. This bioprocess can be realized under conditions suitable for the autotrophic metabolic process, because the process occurred without addition of acetate. H2S emissions from landfill sites would be substantially reduced if this bioprocess was introduced.

  13. 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.

  14. Electrochemically assisted microbial production of hydrogen from acetate.

    PubMed

    Liu, Hong; Grot, Stephen; Logan, Bruce E

    2005-06-01

    Hydrogen production via bacterial fermentation is currently limited to a maximum of 4 moles of hydrogen per mole of glucose, and under these conditions results in a fermentation end product (acetate; 2 mol/mol glucose) that bacteria are unable to further convert to hydrogen. It is shown here that this biochemical barrier can be circumvented by generating hydrogen gas from acetate using a completely anaerobic microbial fuel cell (MFC). By augmenting the electrochemical potential achieved by bacteria in this MFC with an additional voltage of 250 mV or more, it was possible to produce hydrogen at the cathode directly from the oxidized organic matter. More than 90% of the protons and electrons produced by the bacteria from the oxidation of acetate were recovered as hydrogen gas, with an overall Coulombic efficiency (total recovery of electrons from acetate) of 60-78%. This is equivalent to an overall yield of 2.9 mol H2/mol acetate (assuming 78% Coulombic efficiency and 92% recovery of electrons as hydrogen). This bio-electrochemically assisted microbial system, if combined with hydrogen fermentation that produces 2-3 mol H2/mol glucose, has the potential to produce ca. 8-9 mol H2/mol glucose at an energy cost equivalent to 1.2 mol H2/mol glucose. Production of hydrogen by this anaerobic MFC process is not limited to carbohydrates, as in a fermentation process, as any biodegradable dissolved organic matter can theoretically be used in this process to generate hydrogen from the complete oxidation of organic matter.

  15. 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.

  16. Characterization of the formaldehyde-H2O system using combined spectroscopic and mass spectrometry approaches

    NASA Astrophysics Data System (ADS)

    Oancea, A.; Hanoune, B.; Facq, S.; Focsa, C.; Chazallon, B.

    2009-04-01

    The atmosphere is a multiphase reactor in which physical exchange processes, heterogeneous reactions and photochemical reactions take place. The oxygenated organics (formaldehyde, ethanol, acetone etc.) present at trace concentrations into the atmosphere are known to play an important role in atmospheric chemistry due for example to their contribution in the production of HOx radicals, which largely determine the lifetime of pollutants [1]. Further, it has been shown that the interaction of oxygenated organics with ice particles in the atmosphere has the potential to promote heterogeneous chemistry [2]. In the polar lower troposphere, formaldehyde (H2CO) was measured in concentrations that are much higher that those predicted by chemistry models [3]. The mechanism at the origin of the formaldehyde production remains however controversial as the incorporation / partitioning of H2CO in ice crystal has to be determined first. Incorporation of formaldehyde into ice can take place according to several different physical mechanisms like co-condensation, riming, adsorption/desorption. The partitioning of formaldehyde between the gas phase, the liquid and the solid phases is an important parameter that leads to a better understanding of the incorporation mechanisms. In our work, different experimental approaches are used to characterize the partitioning between the different phases in which the H2O-H2CO system exists. Recently, we investigated by mass spectrometry and infrared diode laser spectroscopy the vapor liquid equilibrium (VLE) of formaldehyde aqueous solutions of different concentrations at room temperature. From the data collected on the vapor pressures at atmospherically relevant formaldehyde concentrations, we derived the Henry's coefficients at 295 K [4]. In this study we present first results on the solubility of formaldehyde in ice. This allows a better characterization of the partitioning of formaldehyde vapors above supercooled droplets and/or ice at low

  17. Computational Investigation of the Oxidative Deboronation of Boroglycine, H2N-CH2-B(OH)2, Using H2O and H2O2

    NASA Astrophysics Data System (ADS)

    Larkin, Joseph D.; Markham, George D.; Milkevitch, Matt; Brooks, Bernard R.; Bock, Charles W.

    2009-09-01

    We report results from a computational investigation of the oxidative deboronation of boroglycine, H2N-CH2-B(OH)2, using H2O and H2O2 as the reactive oxygen species (ROS) to yield aminomethanol, H2N-CH2-OH; these results complement our study on the protodeboronation of boroglycine to produce methylamine, H2N-CH3 (Larkin et al. J. Phys. Chem. A 2007, 111, 6489-6500). Second-order Møller-Plesset (MP2) perturbation theory with Dunning-Woon correlation-consistent (cc) basis sets were used for the calculations with comparisons made to results from density functional theory (DFT) at the PBE1PBE/6-311++G(d,p)(cc-pVDZ) levels. The effects of a bulk aqueous environment were also incorporated into the calculations employing PCM and CPCM methodology. Using H2O as the ROS, the reaction H2O + H2N-CH2-B(OH)2 → H2N-CH2-OH + H-B(OH)2 was calculated to be endothermic; the value of ΔH2980 was +12.0 kcal/mol at the MP2(FC)/cc-pVTZ computational level in vacuo and +13.7 kcal/mol in PCM aqueous media; the corresponding value for the activation barrier, ΔH‡, was +94.3 kcal/mol relative to the separated reactants in vacuo and +89.9 kcal/mol in PCM aqueous media. In contrast, the reaction H2O2 + H2N-CH2-B(OH)2 → H2N-CH2-OH + B(OH)3 was calculated to be highly exothermic with an ΔH2980 value of -100.9 kcal/mol at the MP2(FC)/cc-pVTZ computational level in vacuo and -99.6 kcal/mol in CPCM aqueous media; the highest-energy transition state for the multistep process associated with this reaction involved the rearrangement of H2N-CH2-B(OH)(OOH) to H2N-CH2-O-B(OH)2 with a ΔH‡ value of +23.2 kcal/mol in vacuo relative to the separated reactants. These computational results for boroglycine are in accord with the experimental observations for the deboronation of the FDA approved anticancer drug bortezomib (Velcade, PS-341), where it was found to be the principle deactivation pathway (Labutti et al. Chem. Res. Toxicol. 2006, 19, 539-546).

  18. H2S: A Novel Gasotransmitter that Signals by Sulfhydration.

    PubMed

    Paul, Bindu D; Snyder, Solomon H

    2015-11-01

    Hydrogen sulfide (H2S) 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 review focuses on sulfhydration (or persulfidation), which appears to be the principal post-translational modification elicited by H2S.

  19. 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

  20. 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.

  1. 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.

  2. 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!

  3. H2O-mediated trimerization of H2SO4: A computational study and comparison with experimental data

    NASA Astrophysics Data System (ADS)

    Nadykto, A. B.; Nazarenko, K. M.; Jakovleva, M. V.; Uvarova, L. A.; Yu, F.

    2016-06-01

    In the present paper, the formation of stable hydrated (H2SO4)3(H2O)n clusters has been studied using the Density Functional Theory (DFT) at PW91PW91/6-311++(3df,3pd) level. We have found that the hydration of H2SO4 trimers is stronger than that of H2SO4 dimers and tends to decrease at large hydration numbers. We have shown that the affinity of H2SO4 to (H2SO4)2(H2O)n is much higher than that H2SO4 to (H2SO4) (H2O)n. We have compared the equilibrium constants of H2O-mediated trimerization of H2SO4 obtained using PW91PW91/6-311++(3df,3pd) method with experimental data and found that theory and experimentation are in good agreement. The new thermochemical data can be used in a wide range of nucleation studies and can be utilized for the development of quantum-based models of nucleation rates.

  4. 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

  5. Production of high concentrations of H2O2 in a bioelectrochemical reactor fed with real municipal wastewater.

    PubMed

    Modin, Oskar; Fukushi, Kensuke

    2013-01-01

    Bioelectrochemical systems can be used to energy-efficiently produce hydrogen peroxide (H2O2) from wastewater. Organic compounds in the wastewater are oxidized by microorganisms using the anode as electron acceptor. H2O2 is produced by reduction of oxygen on the cathode. In this study, we demonstrate for the first time production of high concentrations of H2O2 production from real municipal wastewater. A concentration of 2.26 g/L H2O2 was produced in 9 h at 8.3 kWh/kgH2O2. This concentration could potentially be useful for membrane cleaning at membrane bioreactor wastewater treatment plants. With an acetate-containing nutrient medium as anode feed, a H2O2 concentration of 9.67 g/L was produced in 21 h at an energy cost of 3.0 kWh/kgH2O2. The bioelectrochemical reactor used in this study suffered from a high internal resistance, most likely caused by calcium carbonate deposits on the cathode-facing side of the cation exchange membrane separating the anode and cathode compartments.

  6. H2O Formation in C-rich AGB Winds

    NASA Astrophysics Data System (ADS)

    Lombaert, R.; Decin, L.; Royer, P.; de Koter, A.; Cox, N. L. J.; De Ridder, J.; Khouri, T.; Agúndez, M.; Blommaert, J. A. D. L.; Cernicharo, J.; González-Alfonso, E.; Groenewegen, M. A. T.; Kerschbaum, F.; Neufeld, D.; Vandenbussche, B.; Waelkens, C.

    2015-08-01

    The Herschel detection of warm H2O vapor emission from C-rich winds of AGB stars challenges the current understanding of circumstellar chemistry. Two mechanisms have been invoked to explain warm H2O formation. In the first, penetration of UV interstellar radiation through a clumpy circumstellar medium causes the formation of H2O molecules in the inner envelope. In the second, periodic shocks passing through the medium immediately above the stellar surface lead to H2O formation. We have identified H2O emission trends from distance-independent line-strength ratios in a sample of 18 C-rich AGB sources, by comparing to a theoretical model grid. We detect warm H2O emission close to or inside the acceleration zone of all sample stars. We find an anti-correlation between the H2O/CO line-strength ratios and the mass-loss rate for Mgas>3×10-7 M⊙/yr. This implies that the H2O formation mechanism becomes less efficient with increasing envelope column density. The anti-correlation breaks down for SRb objects, which clump together at an overall lower H2O abundance. Finally, a radial dependence of the H2O abundance within individual sources is unlikely. These findings lend support to shock-induced non-equilibrium chemistry as the primary source of H2O formation in C-rich AGB stars.

  7. A Proposal for Climate Stability on H2-greenhouse Planets

    NASA Astrophysics Data System (ADS)

    Abbot, Dorian S.

    2015-12-01

    A terrestrial planet in an orbit far outside of the standard habitable zone could maintain surface liquid water as a result of H2-H2 collision-induced absorption by a thick H2 atmosphere. Without a stabilizing climate feedback, however, habitability would be accidental and likely brief. In this letter I propose stabilizing climate feedbacks for such a planet that require only that biological functions have an optimal temperature and operate less efficiently at other temperatures. For example, on a planet with a net source of H2 from its interior, H2-consuming life (such as methanogens) could establish a stable climate. If a positive perturbation is added to the equilibrium temperature, H2 consumption by life will increase (cooling the planet) until the equilibrium climate is reestablished. The potential existence of such feedbacks makes H2-warmed planets more attractive astrobiological targets.

  8. Chemiluminescent Detection of Enzymatically Produced H2S

    PubMed Central

    Bailey, T. Spencer; Pluth, Michael D.

    2015-01-01

    Hydrogen sulfide (H2S) has emerged as an important biological signaling molecule. To better understand the multifaceted biological roles of H2S, the development of selective and sensitive biocompatible assays for H2S is becoming increasingly important. Motivated by these challenges, our laboratory is developing new methods to further detect and monitor biological H2S. Here, we describe in detail our recent advances in the development and the use of chemiluminescence-based H2S sensors to assist other investigators with use of these chemical tools. We highlight the use of these tools use by displaying their selectivity and high sensitivity toward H2S and provide examples of assays we have developed to detect enzymatically produced H2S. PMID:25725517

  9. A proposal for climate stability on H2-greenhouse planets

    NASA Astrophysics Data System (ADS)

    Abbot, D. S.

    2015-12-01

    A terrestrial planet in an orbit far outside of the standard habitable zone could maintain surface liquid water as a result of H2-H2 collision-induced absorption by a thick H2 atmosphere. Without a stabilizing climate feedback, however, habitability would be accidental and likely brief. We propose a stabilizing climate feedback for such a planet that requires only biological production of H2 to balance net loss to space that has some optimal temperature, and operates less efficiently at higher temperatures. A stable feedback is possible on such a planet through which a perturbation increasing temperature decreases H2 production, which decreases H2 greenhouse warming and therefore temperature. The potential of such a feedback makes H2-warmed planets more attractive astrobiological targets.

  10. 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

  11. Mice without MacroH2A Histone Variants

    PubMed Central

    Changolkar, Lakshmi N.; Costanzi, Carl; Leu, N. Adrian

    2014-01-01

    MacroH2A core histone variants have a unique structure that includes a C-terminal nonhistone domain. They are highly conserved in vertebrates and are thought to regulate gene expression. However, the nature of genes regulated by macroH2As and their biological significance remain unclear. Here, we examine macroH2A function in vivo by knocking out both macroH2A1 and macroH2A2 in the mouse. While macroH2As are not required for early development, the absence of macroH2As impairs prenatal and postnatal growth and can significantly reduce reproductive efficiency. The distributions of macroH2A.1- and macroH2A.2-containing nucleosomes show substantial overlap, as do their effects on gene expression. Our studies in fetal and adult liver indicate that macroH2As can exert large positive or negative effects on gene expression, with macroH2A.1 and macroH2A.2 acting synergistically on the expression of some genes and apparently having opposing effects on others. These effects are very specific and in the adult liver preferentially involve genes related to lipid metabolism, including the leptin receptor. MacroH2A-dependent gene regulation changes substantially in postnatal development and can be strongly affected by fasting. We propose that macroH2As produce adaptive changes to gene expression, which in the liver focus on metabolism. PMID:25312643

  12. 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. PMID:27430512

  13. State-specific Dissociation Rates for H2(v, j) + H2(v‧, j‧)

    NASA Astrophysics Data System (ADS)

    Mandy, M. E.

    2016-08-01

    State-specific rate coefficients for the dissociation of H2 as the result of collisions with H2 were calculated for all combinations of (v, j) with an internal energy below 1 eV. Full-dimensional quasiclassical trajectories were calculated using the BMKP2 interaction potential with a minimum of 80,000 trajectories at each translational energy. Additional large batches of trajectories were carried out to calculate the cross sections near the threshold to dissociation to attain the desired precision of the rate coefficients. A piecewise linear excitation function was used to calculate the rate coefficient between 100 and 100,000 K. The resulting state-specific rate coefficients, γ, were parametrized as a function of temperature over the range 600-10,000 K using: {{log}}10 γ (t)=a+{bz}+{{cz}}2-d≤ft(\\displaystyle \\frac{1}{t}-1\\right) where t=T/4500 K and z={{log}}10 t. The values of the resulting rate coefficients were sensitive to the internal energy of both molecules, with initial vibrational energy having a slightly greater effect than rotational energy. This effect diminished as temperature increased.

  14. Analysis of the H(2)(+) with H(2) reaction using electron nuclear dynamics

    NASA Astrophysics Data System (ADS)

    Oreiro, Juan J. G.

    The END formalism addresses the solution of the time- dependent Schrodinger equation, treating both electrons and nuclei simultaneously. It differs from the other traditional fully quantum mechanical time-dependent methods in that it does not require a potential energy surface (PES) to carry the nuclear motion. The interaction between electronic and nuclear motion is, therefore, obtained in a transparent way, not relying on PES gradients to obtain the coupling between electrons and nuclei. We analyze the H2+ + H2 reaction at energies below 4 eV using different approximations and basis sets. Other than the choice of initial conditions, form of wave function, and basis set, no constraints are imposed on the system evolution. The nuclei are treated in the classical limit, and the electronic part is described by a single determinantal, unrestricted wave function. We obtain properties, such as Mulliken populations, transition probabilities, and cross-sections, from the resulting trajectories. These results are compared with other current theoretical approaches, and with experimental values. The relevance of the electron- nuclear coupling is estimated by comparing the END trajectories with molecular dynamics calculations for selected initial conditions in different basis sets.

  15. Acetate dependence of tumors.

    PubMed

    Comerford, Sarah A; Huang, Zhiguang; Du, Xinlin; Wang, Yun; Cai, Ling; Witkiewicz, Agnes K; Walters, Holly; Tantawy, Mohammed N; Fu, Allie; Manning, H Charles; Horton, Jay D; Hammer, Robert E; McKnight, Steven L; Tu, Benjamin P

    2014-12-18

    Acetyl-CoA represents a central node of carbon metabolism that plays a key role in bioenergetics, cell proliferation, and the regulation of gene expression. Highly glycolytic or hypoxic tumors must produce sufficient quantities of this metabolite to support cell growth and survival under nutrient-limiting conditions. Here, we show that the nucleocytosolic acetyl-CoA synthetase enzyme, ACSS2, supplies a key source of acetyl-CoA for tumors by capturing acetate as a carbon source. Despite exhibiting no gross deficits in growth or development, adult mice lacking ACSS2 exhibit a significant reduction in tumor burden in two different models of hepatocellular carcinoma. ACSS2 is expressed in a large proportion of human tumors, and its activity is responsible for the majority of cellular acetate uptake into both lipids and histones. These observations may qualify ACSS2 as a targetable metabolic vulnerability of a wide spectrum of tumors.

  16. 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)

  17. 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.

  18. 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.

  19. H2-forming N5,N10-methylenetetrahydromethanopterin dehydrogenase: mechanism of H2 formation analyzed using hydrogen isotopes.

    PubMed

    Klein, A R; Fernández, V M; Thauer, R K

    1995-07-17

    H2-forming N5,N10-methylenetetrahydromethanopterin dehydrogenase catalyzes the reversible dehydrogenation of N5,N10-methylenetetrahydromethanopterin (CH2 = H4MPT) to N5,N10-methenyltetrahydromethanopterin (CH = H4MPT+) and H2. In D2O both HD and D2 are formed from CH2 = H4MPT and in H2O both HD and H2 from CD2 = H4MPT. Evidence is presented that HD is not an intermediate in the formation of D2 and H2, respectively.

  20. Hydrogen Production from Ethanol Steam Reforming over Supported Cobalt Catalysts

    SciTech Connect

    Lin, Sean S.-Y.; Kim, Do Heui; Ha, Su Y.

    2008-05-01

    Hydrogen production was carried out via ethanol steam reforming over supported cobalt catalysts. Wet incipient impregnation method was used to support cobalt on ZrO2, CeO2 and CeZrO4 followed by pre-reduction with H2 up to 677 °C to attain supported cobalt catalysts. It was found that the non-noble metal based 10 wt % Co/CeZrO4 is an efficient catalyst to achieve ethanol conversion of 100% and hydrogen yield of 82% (4.9 mol H2/ mol ethanol) at 450 oC , which is superior to 0.5 wt % Rh/Al2O3. The pre-reduction process is required to activate supported cobalt catalysts for high H2 yield of ethanol steam reforming. In addition, support effect is found significant for cobalt during ethanol steam reforming. 10% Co/CeO2 gave high H2 selectivity while suffered low conversion due to the poor thermal stability. In contrast to CeO2, 10 wt % Co/ZrO2 achieved high conversion while suffered lower H2 yield due to the production of methane. The synergistic effect of ZrO2 and CeO2 to promote high ethanol conversion while suppress methanation was observed when CeZrO4 was used as a support for cobalt. This synergistic effect of CeZrO4 support leads to a high hydrogen yield at low temperature for 10 wt % Co/CeZrO4 catalyst. Under the high weight hourly space velocity (WHSV) of ethanol (2.5 h-1), the hydrogen yield over 10 wt % Co/CeZrO4 was found to gradually decrease to 70% of its initial value in 6 hours possibly due to the coke formation on the catalyst.

  1. Hydroxytyrosol glucuronides protect renal tubular epithelial cells against H(2)O(2) induced oxidative damage.

    PubMed

    Deiana, Monica; Incani, Alessandra; Rosa, Antonella; Atzeri, Angela; Loru, Debora; Cabboi, Barbara; Paola Melis, M; Lucas, Ricardo; Morales, Juan C; Assunta Dessì, M

    2011-09-30

    Hydroxytyrosol (2-(3',4'-dihydroxyphenyl)ethanol; HT), the most active ortho-diphenolic compound, present either in free or esterified form in extravirgin olive oil, is extensively metabolized in vivo mainly to O-methylated, O-sulfated and glucuronide metabolites. We investigated the capacity of three glucuronide metabolites of HT, 3'-O-β-d-glucuronide and 4'-O-β-d-glucuronide derivatives and 2-(3',4'-dihydroxyphenyl)ethanol-1-O-β-d-glucuronide, in comparison with the parent compound, to inhibit H(2)O(2) induced oxidative damage and cell death in LLC-PK1 cells, a porcine kidney epithelial cell line. H(2)O(2) treatment exerted a toxic effect inducing cell death, interacting selectively within the pro-death extracellular-signal relate kinase (ERK 1/2) and the pro-survival Akt/PKB signaling pathways. It also produced direct oxidative damage initiating the membrane lipid peroxidation process. None of the tested glucuronides exhibited any protection against the loss in renal cell viability. They also failed to prevent the changes in the phosphorylation states of ERK and Akt, probably reflecting their inability to enter the cells, while HT was highly effective. Notably, pretreatment with glucuronides exerted a protective effect at the highest concentration tested against membrane oxidative damage, comparable to that of HT: the formation of malondialdehyde, fatty acid hydroperoxides and 7-ketocholesterol was significantly inhibited.

  2. 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.

  3. Engineering Escherichia coli for improved ethanol production from gluconate.

    PubMed

    Hildebrand, Amanda; Schlacta, Theresa; Warmack, Rebeccah; Kasuga, Takao; Fan, Zhiliang

    2013-10-10

    We report on engineering Escherichia coli to produce ethanol at high yield from gluconic acid (gluconate). Knocking out genes encoding for the competing pathways (l-lactate dehydrogenase and pyruvate formate lyase A) in E. coli KO11 eliminated lactate production, lowered the carbon flow toward acetate production, and improved the ethanol yield from 87.5% to 97.5% of the theoretical maximum, while the growth rate of the mutant strain was about 70% of the wild type. The corresponding genetic modifications led to a small improvement of ethanol yield from 101.5% to 106.0% on glucose. Deletion of the pyruvate dehydrogenase gene (pdh) alone improved the ethanol yield from 87.5% to 90.4% when gluconate was a substrate. The growth rate of the mutant strain was identical to that of the wild type. The corresponding genetic modification led to no improvements on ethanol yield on glucose.

  4. 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.

  5. The role of endogenous H2S in cardiovascular physiology.

    PubMed

    Skovgaard, Nini; Gouliaev, Anja; Aalling, Mathilde; Simonsen, Ulf

    2011-09-01

    Recent research has shown that the endogenous gas hydrogen sulphide (H2S) is a signalling molecule of considerable biological potential and has been suggested to be involved in a vast number of physiological processes. In the vascular system, H2S is synthesized from cysteine by cystathionine-γ-lyase (CSE) in smooth muscle cells (SMC) and 3- mercaptopyruvate sulfuresterase (3MST) and CSE in the endothelial cells. In pulmonary and systemic arteries, H2S induces relaxation and/or contraction dependent on the concentration of H2S, type of vessel and species. H2S relaxes SMC through a direct effect on KATP-channels or Kv-channels causing hyperpolarization and closure of voltage-dependent Ca2+-channels followed by a reduction in intracellular calcium. H2S also relaxes SMC through the release of endothelium- derived hyperpolarizing factor (EDHF) and nitric oxide (NO) from the endothelium. H2S contracts SMC through a reduction in nitric oxide (NO) availability by reacting with NO forming a nitrosothiol compound and through an inhibitory effect on endothelial nitric oxide synthase (eNOS) as well as a reduction in SMC cyclic AMP concentration. Evidence supports a role for H2S in oxygen sensing. Furthermore, reduced endogenous H2S production may also play a role in ischemic heart diseases and hypertension, and treatment with H2S donors and cysteine analogues may be beneficial in treatment of cardiovascular disease.

  6. Communication: the origin of rotational enhancement effect for the reaction of H2O(+) + H2 (D2).

    PubMed

    Li, Anyang; Li, Yongle; Guo, Hua; Lau, Kai-Chung; Xu, Yuntao; Xiong, Bo; Chang, Yih-Chung; Ng, C Y

    2014-01-01

    We have measured the absolute integral cross sections (σ's) for H3O(+) formed by the reaction of rovibrationally selected H2O(+)(X(2)B1; v1 (+)v2 (+)v3 (+) = 000; N(+) K a (+) K c (+) = 000, 111, and 211) ion with H2 at the center-of-mass collision energy (Ecm) range of 0.03-10.00 eV. The σ(000), σ(111), and σ(211) values thus obtained reveal rotational enhancements at low Ecm < 0.50 eV, in agreement with the observation of the previous study of the H2O(+)(X(2)B1) + D2 reaction. This Communication presents important progress concerning the high-level ab initio quantum calculation of the potential energy surface for the H2O(+)(X(2)B1) + H2 (D2) reactions, which has provided valuable insight into the origin of the rotational enhancement effect. Governed by the charge and dipole-induced-multipole interactions, the calculation shows that H2 (D2) approaches the H end of H2O(+)(X(2)B1) in the long range, whereas chemical force in the short range favors the orientation of H2 (D2) toward the O side of H2O(+). The reorientation of H2O(+) reactant ion facilitated by rotational excitation thus promotes the H2O(+) + H2 (D2) reaction along the minimum energy pathway, rendering the observed rotational enhancement effects. The occurrence of this effect at low Ecm indicates that the long range charge and dipole-induced-multipole interactions of the colliding pair play a significant role in the dynamics of the exothermic H2O(+) + H2 (D2) reactions.

  7. Decrease of H2O2 plasma membrane permeability during adaptation to H2O2 in Saccharomyces cerevisiae.

    PubMed

    Branco, Miguel R; Marinho, H Susana; Cyrne, Luisa; Antunes, Fernando

    2004-02-20

    Contrary to what is widely believed, recent published results show that H2O2 does not freely diffuse across biomembranes. The fast removal of H2O2 by antioxidant enzymes is able to generate a gradient if H2O2 is produced in a different compartment from that containing the enzymes (Antunes, F., and Cadenas, E. (2000) FEBS Lett. 475, 121-126). In this work, we extended these studies and tested whether an active regulation of biomembranes permeability characteristics is part of the cell response to oxidative stress. Using Saccharomyces cerevisiae as a model, we showed that: (a) H2O2 gradients across the plasma membrane are formed upon exposure to external H2O2; (b) there is a correlation between the magnitude of the gradients and the resistance to H2O2; (c) there is not a correlation between the intracellular capacity to remove H2O2 and the resistance to H2O2; (d) the plasma membrane permeability to H2O2 decreases by a factor of two upon acquisition of resistance to this agent by pre-exposing cells either to nonlethal doses of H2O2 or to cycloheximide, an inhibitor of protein synthesis; and (e) erg3Delta and erg6Delta mutants, which have impaired ergosterol biosynthesis pathways, show higher plasma membrane permeability to H2O2 and are more sensitive to H2O2. Altogether, the regulation of the plasma membrane permeability to H2O2 emerged as a new mechanism by which cells respond and adapt to H2O2. The consequences of the results to cellular redox compartmentalization and to the origin and evolution of the eukaryotic cell are discussed.

  8. H2O-H2SO4 system in Venus' clouds and OCS, CO, and H2SO4 profiles in Venus' troposphere.

    PubMed

    Krasnopolsky, V A; Pollack, J B

    1994-05-01

    A coupled problem of diffusion and condensation is solved for the H2SO4-H2O system in Venus' cloud layer. The position of the lower cloud boundary and profiles of the H2O and H2SO4 vapor mixing ratios and of the H2O/H2SO4 ratio of sulfuric acid aerosol and its flux are calculated as functions of the column photochemical production rate of sulfuric acid, phi H2SO4. Variations of the lower cloud boundary are considered. Our basic model, which is constrained to yield fH2O (30 km) = 30 ppm (Pollack et al. 1993), predicts the position of the lower cloud boundary at 48.4 km coinciding with the mean Pioneer Venus value, the peak H2SO4 mixing ratio of 5.4 ppm, and the H2SO4 production rate phi H2SO4 = 2.2 x 10(12) cm-2 sec-1. The sulfur to sulfuric acid mass flux ratio in the clouds is 1 : 27 in this model, and the mass loading ratio may be larger than this value if sulfur particles are smaller than those of sulfuric acid. The model suggests that the extinction coefficient of sulfuric acid particles with radius 3.7 micrometers (mode 3) is equal to 0.3 km-1 in the middle cloud layer. The downward flux of CO is equal to 1.7 x 10(12) cm-2 sec-1 in this model. Our second model, which is constrained to yield fH2SO4 = 10 ppm at the lower cloud boundary, close to the value measured by the Magellan radiooccultations, predicts the position of this boundary to be at 46.5 km, which agrees with the Magellan data; fH2O(30 km) = 90 ppm, close to the data of Moroz et al. (1983) at this altitude; phi H2SO4 = 6.4 x 10(12) cm-2 sec-1; and phi co = 4.2 x 10(12) cm-2 sec-1. The S/H2SO4 flux mass ratio is 1 : 18, and the extinction coefficient of the mode 3 sulfuric acid particles is equal to 0.9 km-1 in the middle cloud layer. A strong gradient of the H2SO4 vapor mixing ratio near the bottom of the cloud layer drives a large upward flux of H2SO4, which condenses and forms the excessive downward flux of liquid sulfuric acid, which is larger by a factor of 4-7 than the flux in the middle cloud

  9. H2O-H2SO4 system in Venus' clouds and OCS, CO, and H2SO4 profiles in Venus' troposphere.

    PubMed

    Krasnopolsky, V A; Pollack, J B

    1994-05-01

    A coupled problem of diffusion and condensation is solved for the H2SO4-H2O system in Venus' cloud layer. The position of the lower cloud boundary and profiles of the H2O and H2SO4 vapor mixing ratios and of the H2O/H2SO4 ratio of sulfuric acid aerosol and its flux are calculated as functions of the column photochemical production rate of sulfuric acid, phi H2SO4. Variations of the lower cloud boundary are considered. Our basic model, which is constrained to yield fH2O (30 km) = 30 ppm (Pollack et al. 1993), predicts the position of the lower cloud boundary at 48.4 km coinciding with the mean Pioneer Venus value, the peak H2SO4 mixing ratio of 5.4 ppm, and the H2SO4 production rate phi H2SO4 = 2.2 x 10(12) cm-2 sec-1. The sulfur to sulfuric acid mass flux ratio in the clouds is 1 : 27 in this model, and the mass loading ratio may be larger than this value if sulfur particles are smaller than those of sulfuric acid. The model suggests that the extinction coefficient of sulfuric acid particles with radius 3.7 micrometers (mode 3) is equal to 0.3 km-1 in the middle cloud layer. The downward flux of CO is equal to 1.7 x 10(12) cm-2 sec-1 in this model. Our second model, which is constrained to yield fH2SO4 = 10 ppm at the lower cloud boundary, close to the value measured by the Magellan radiooccultations, predicts the position of this boundary to be at 46.5 km, which agrees with the Magellan data; fH2O(30 km) = 90 ppm, close to the data of Moroz et al. (1983) at this altitude; phi H2SO4 = 6.4 x 10(12) cm-2 sec-1; and phi co = 4.2 x 10(12) cm-2 sec-1. The S/H2SO4 flux mass ratio is 1 : 18, and the extinction coefficient of the mode 3 sulfuric acid particles is equal to 0.9 km-1 in the middle cloud layer. A strong gradient of the H2SO4 vapor mixing ratio near the bottom of the cloud layer drives a large upward flux of H2SO4, which condenses and forms the excessive downward flux of liquid sulfuric acid, which is larger by a factor of 4-7 than the flux in the middle cloud

  10. H2O-H2SO4 system in Venus' clouds and OCS, CO, and H2SO4 profiles in Venus' troposphere

    NASA Astrophysics Data System (ADS)

    Krasnopolsky, V. A.; Pollack, J. B.

    1994-05-01

    A coupled problem of diffusion and condensation is solved for the H2SO4-H2O system in Venus' cloud layer. The position of the lower cloud boundary and profiles of the H2O and H2SO4 vapor mixing ratios and of the H2O/H2SO4 ratio of sulfuric acid aerosol and its flux are calculated as functions of the column photochemical production rate of sulfuric acid, PhiH2SO4. Variations of the lower cloud boundary are considered. Our basic model, which is constrained to yield fH2O (30 km) = 30 ppm (Pollack et al. 1993), predicts the position of the lower cloud boundary at 48.4 km coinciding with the mean Pioneer Venus value, the peak H2SO4 mixing ratio of 5.4 ppm, and the H2SO4 production rate PhiH2SO4 = 2.2 x 1012/sq cm/s. The sulfur to sulfuric acid mass flux ratio in the clouds is 1:27 in this model, and the mass loading ratio may be larger than this value if sulfur particles are smaller than those of sulfuric acid. The model suggests that the extinction coefficient of sulfuric acid particles with radius 3.7 micrometers (mode 3) is equal to 0.3/km in the middle cloud layer. The downward flux of CO is equal to 1.7 x 1012/sq cm/s in this model. Our second model, which is constrained to yield fH2O = 10 ppm at the lower cloud boundary, close to the value measured by the Magellan radio occultations, predicts the position of this boundary to be at 46.5 km, which agrees with the Magellan data; fH2O (30 km) = 90 ppm, close to the data of Moroz et al. (1983) at this altitude; PhiH2SO4 = 6.4 x 1012/sq cm/s; and Phico = 4.2 x 1012/sq cm/s. The S/H2SO4 flux mass ratio is 1:18, and the extinction coefficient of the mode 3 sulfuric acid particles is equal to 0.9 km in the middle cloud layer. A strong gradient of the H2SO4 vapor mixing ratio near the bottom of the cloud layer drives a large upward flux of H2SO4, which condenses and forms the excessive downward flux of liquid sulfuric acid, which is larger by a factor of 4-7 than the flux in the middle cloud layer. This is the mechanism of

  11. H2O-H2SO4 system in Venus' clouds and OCS, CO, and H2SO4 profiles in Venus' troposphere

    NASA Technical Reports Server (NTRS)

    Krasnopolsky, V. A.; Pollack, J. B.

    1994-01-01

    A coupled problem of diffusion and condensation is solved for the H2SO4-H2O system in Venus' cloud layer. The position of the lower cloud boundary and profiles of the H2O and H2SO4 vapor mixing ratios and of the H2O/H2SO4 ratio of sulfuric acid aerosol and its flux are calculated as functions of the column photochemical production rate of sulfuric acid, Phi(sub H2SO4). Variations of the lower cloud boundary are considered. Our basic model, which is constrained to yield f(sub H2O) (30 km) = 30 ppm (Pollack et al. 1993), predicts the position of the lower cloud boundary at 48.4 km coinciding with the mean Pioneer Venus value, the peak H2SO4 mixing ratio of 5.4 ppm, and the H2SO4 production rate Phi(sub H2SO4) = 2.2 x 10(exp 12)/sq cm/s. The sulfur to sulfuric acid mass flux ratio in the clouds is 1:27 in this model, and the mass loading ratio may be larger than this value if sulfur particles are smaller than those of sulfuric acid. The model suggests that the extinction coefficient of sulfuric acid particles with radius 3.7 micrometers (mode 3) is equal to 0.3/km in the middle cloud layer. The downward flux of CO is equal to 1.7 x 10(exp 12)/sq cm/s in this model. Our second model, which is constrained to yield f(sub H2O) = 10 ppm at the lower cloud boundary, close to the value measured by the Magellan radiooccultations, predicts the position of this boundary to be at 46.5 km, which agrees with the Magellan data; f(sub H2O) (30 km) = 90 ppm, close to the data of Moroz et al. (1983) at this altitude; Phi(sub H2SO4) = 6.4 x 10(exp 12)/sq cm/s; and Phi(sub co) = 4.2 x 10(exp 12)/sq cm/s. The S/H2SO4 flux mass ratio is 1:18, and the extinction coefficient of the mode 3 sulfuric acid particles is equal to 0.9 km in the middle cloud layer. A strong gradient of the H2SO4 vapor mixing ratio near the bottom of the cloud layer drives a large upward flux of H2SO4, which condenses and forms the excessive downward flux of liquid sulfuric acid, which is larger by a factor of 4

  12. 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

  13. Metabolic engineering to improve ethanol production in Thermoanaerobacter mathranii.

    PubMed

    Yao, Shuo; Mikkelsen, Marie Just

    2010-09-01

    Thermoanaerobacter mathranii can produce ethanol from lignocellulosic biomass at high temperatures, but its biotechnological exploitation will require metabolic engineering to increase its ethanol yield. With a cofactor-dependent ethanol production pathway in T. mathranii, it may become crucial to regenerate cofactor to increase the ethanol yield. Feeding the cells with a more reduced carbon source, such as mannitol, was shown to increase ethanol yield beyond that obtained with glucose and xylose. The ldh gene coding for lactate dehydrogenase was previously deleted from T. mathranii to eliminate an NADH oxidation pathway. To further facilitate NADH regeneration used for ethanol formation, a heterologous gene gldA encoding an NAD(+)-dependent glycerol dehydrogenase was expressed in T. mathranii. One of the resulting recombinant strains, T. mathranii BG1G1 (Deltaldh, P(xyl)GldA), showed increased ethanol yield in the presence of glycerol using xylose as a substrate. With an inactivated lactate pathway and expressed glycerol dehydrogenase activity, the metabolism of the cells was shifted toward the production of ethanol over acetate, hence restoring the redox balance. It was also shown that strain BG1G1 acquired the capability to utilize glycerol as an extra carbon source in the presence of xylose, and utilization of the more reduced substrate glycerol resulted in a higher ethanol yield.

  14. H2 adsorption in Li-decorated porous graphene

    NASA Astrophysics Data System (ADS)

    Seenithurai, S.; Pandyan, R. Kodi; Kumar, S. Vinodh; Munieswaran, P.; Saranya, C.; Mahendran, M.

    2015-06-01

    Porous graphene (PG) has been decorated with Li atoms and subsequently studied the hydrogen (H2) adsorption characteristics, by using Density Functional Theory (DFT)-based calculations. A 2×2 PG has been decorated with eight Li atoms. Upto four H2 molecules get adsorbed on each Li atom. The maximum H2 storage capacity that could be achieved in 2×2PG-8Li is 8.95 wt% which is higher than the U.S. DOE's revised target for the on-board vehicles. The average H2 adsorption binding energy is 0.535 eV/H2, which lies between 0.2-0.6 eV/H2 that is required for achieving adsorption and desorption at near ambient conditions. Thus, Li-decorated PG could be a viable option for on-board automobile applications.

  15. 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.

  16. 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. PMID:25698512

  17. 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.

  18. 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.

  19. Nucleosome adaptability conferred by sequence and structural variations in histone H2A-H2B dimers

    PubMed Central

    Shaytan, Alexey K.; Landsman, David

    2015-01-01

    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. PMID:25731851

  20. Microwave Spectra and Structures of H_2S-CuCl and H_2O-CuCl.

    NASA Astrophysics Data System (ADS)

    Walker, N. R.; Wheatley, D. E.; Stephens, S. L.; Roberts, F. J.; Mikhailov, V. A.; Legon, A. C.

    2010-06-01

    A Balle-Flygare FT-MW spectrometer coupled to a laser ablation source has been used to measure the pure rotational spectra of H2S-CuCl and H2O-CuCl. Both molecules are generated via laser ablation (532 nm) of a metal rod in the presence of CCl4, argon, a low partial pressure of H2S or H2O and are stabilized by supersonic expansion. Rotational constants and centrifugal distortion constants have been measured for eight isotopologues of H2S-CuCl with substitutions available at the copper, chlorine and hydrogen atoms. Transitions in the spectra of nine isotopologues of H2O-CuCl have been measured with isotopic substitutions achieved for every atom. The spectra of both H2S-CuCl and H2O-CuCl are consistent with a linear arrangement of sulphur or oxygen, metal and chlorine atoms. The structure of H2S-CuCl is pyramidal with CS symmetry. The structure of H2O-CuCl is either C2v planar at equilibrium or CS pyramidal but with a low potential-energy barrier to planarity such that the v=0 and 1 states associated with the motion that inverts the configuration at the O atom are well separated. Nuclear quadrupole coupling constants have been measured for the chlorine and copper atoms in each molecule. Nuclear spin-rotation constants have been determined for the copper atom.

  1. 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

  2. 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. PMID:26162830

  3. Presence of histone H2B in Trypanosoma cruzi chromatin.

    PubMed

    Toro, G C; Wernstedt, C; Hellman, U; Galanti, N

    1993-01-01

    The organization of chromatin in protists presents some characteristic features. In Trypanosoma cruzi, no condensation of chromatin into chromosomes is observed during cell division. A systematic characterization of histones should provide information on this peculiar behaviour. Histone H2B from this parasite was characterized by selective dissociation from chromatin in 0.8 M NaCl, by its elution pattern in narrow-bore reversed phase high performance liquid chromatography, by polyacrylamide gel electrophoresis and by partial sequencing of its amino terminal domain. This chromosomal protein differs from histone H2B of other species. The first 12 amino acids are missing which explains its lower molecular weight when compared to human histone H2B. Correspondingly, the amino terminal domain of T. cruzi histone H2B is 25-30% shorter than other histones H2B. Moreover, three out of four acetylation sites present in human histone H2B are missing in T. cruzi histone H2B. The differences in size and in acceptor sites for acetylation of T. cruzi histone H2B when compared to human histone H2B may represent a functional feature to consider for the understanding of the chromatin cycle of condensation in this parasite.

  4. Acetic acid-water complex: The first observation of structures containing the higher-energy acetic acid conformer

    NASA Astrophysics Data System (ADS)

    Lopes, Susy; Fausto, Rui; Khriachtchev, Leonid

    2016-02-01

    Non-covalent interaction of acetic acid (AA) and water is studied experimentally by IR spectroscopy in a nitrogen matrix and theoretically at the MP2 and coupled-cluster with single and double and perturbative triple excitations [CCSD(T)]/6-311++G(2d,2p) levels of theory. This work is focused on the first preparation and characterization of complexes of higher-energy (cis) conformer of AA with water. The calculations show three 1:1 structures for the trans-AA⋯H2O complexes and three 1:1 structures for the cis-AA⋯H2O complexes. Two trans-AA⋯H2O and two cis-AA⋯H2O complexes are found and structurally assigned in the experiments. The two cis-AA⋯ ṡ H2O complexes are obtained by annealing of a matrix containing water and cis-AA molecules prepared by selective vibrational excitation of the ground-state trans form. The less stable trans-AA⋯H2O complex is obtained by vibrational excitation of the less stable cis-AA⋯H2O complex. In addition, the 1:2 complexes of trans-AA and cis-AA with water molecules are studied computationally and the most stable forms of the 1:2 complexes are experimentally identified.

  5. 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

  6. 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

  7. Inhibition of acetate ester biosynthesis in banana (Musa sapientum L.) fruit pulp under anaerobic conditions.

    PubMed

    Wendakoon, Sumithra K; Ueda, Yoshinori; Imahori, Yoshihiro; Ishimaru, Megumi

    2004-03-24

    The effect of anaerobic conditions on acetate ester biosynthesis in ripened banana pulp was investigated. Incubation of the pulp in less than 1% O(2) resulted in a significant reduction in the formation of ethyl acetate. Regardless of the presence of a large amount of endogenous ethanol and the remaining exogenous isobutyl alcohol after complete anaerobic incubation with the pulp, the production of acetate ester decreased. The effect of addition of pyruvate, isobutyl alcohol, acetate, and methyl hexanoate on acetate ester formation in 100% N(2) was also investigated. The addition of pyruvate and isobutyl alcohol to the pulp gave lower acetate esters in N(2) than in air, whereas the pulp incubated with acetate and isobutyl alcohol produced more acetate ester in both conditions. Therefore, the lack of acetyl CoA, or more precisely acetate, in the tissue is the main reason for the inhibition of acetate ester formation under anaerobic conditions. The activity of beta-oxidation measured by incubation with methyl hexanoate was detected only in the samples incubated in air. The formation of acetyl CoA, derived from pyruvate through mitochondria and through beta-oxidation, was inhibited by anaerobic conditions, which suggests that mitochondrial activity and/or beta-oxidation are essential for ester biosynthesis.

  8. The tropospheric cycle of H2: a critical review

    NASA Astrophysics Data System (ADS)

    Ehhalt, D. H.; Rohrer, F.

    2009-07-01

    The literature on the distribution, budget and isotope content of molecular hydrogen (H2) in the troposphere is critically reviewed. The global distribution of H2 is reasonably well established and is relatively uniform. The surface measurements exhibit a weak latitudinal gradient with 3% higher concentrations in the Southern Hemisphere and seasonal variations that maximize in arctic latitudes and the interior of continents with peak-to-peak amplitudes up to 10%. There is no evidence for a continuous long-term trend, but older data suggest a reversal of the interhemispheric gradient in the late 1970s, and an increase in the deuterium content of H2 in the Northern Hemisphere from 80‰ standard mean ocean water (SMOW) in the 1970s to 130‰ today. The current budget analyses can be divided in two classes: bottom up, in which the source and sink terms are estimated separately based on emission factors and turnovers of precursors and on global integration of regional loss rates, respectively. That category includes the analyses by 3-D models and furnishes tropospheric turnovers around 75 Tg H2 yr-1. The other approach, referred to as top down, relies on inverse modelling or analysis of the deuterium budget of tropospheric H2. These provide a global turnover of about 105 Tg H2 yr-1. The difference is due to a much larger sink strength by soil uptake and a much larger H2 production from the photochemical oxidation of volatile organic compounds (VOC) in the case of the top down approaches. The balance of evidence seems to favour the lower estimates-mainly due to the constraint placed by the global CO budget on the H2 production from VOC. An update of the major source and sink terms yields: fossil fuel use 11 +/- 4 Tg H2 yr-1 biomass burning (including bio-fuel) 15 +/- 6 Tg H2 yr-1 nitrogen fixation (ocean) 6 +/- 3 Tg H2 yr-1 nitrogen fixation (land) 3 +/- 2 Tg H2 yr-1 photochemical production from CH4 23 +/- 8 Tg H2 yr-1 and photochemical production from other VOC 18

  9. 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

  10. 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.

  11. Alternative processing of H-2Dd pre-mRNAs results in membrane expression of differentially phosphorylated protein products.

    PubMed Central

    McCluskey, J; Boyd, L F; Maloy, W L; Coligan, J E; Margulies, D H

    1986-01-01

    Two distinct mRNA species encoding the mouse major histocompatibility antigen H-2Dd have been identified in BALB/c spleen cells as well as in cultured cell lines expressing this cell surface glycoprotein. The alternate transcripts of H-2Dd arise from either removal or inclusion of exon VII (encoding I2) during pre-mRNA processing. The relative levels of each kind of H-2Dd transcript varied considerably between different cell types, and in all cells examined both forms of alloantigen were expressed on the cell membrane. Antigen derived from both types of transcript reacted with H-2Dd-specific monoclonal antibodies, whereas only protein lacking the 13 amino acids of I2 reacted with a specific antiserum raised against a predicted exon VI/VIII fusion peptide. Those H-2Dd proteins translated from full length, but not smaller, transcripts were phosphorylated in resting and phorbol myristate acetate-stimulated BALB/c spleen cells, suggesting that the major site of in vivo phosphorylation is within the highly conserved sequence encoded by exon VII. Thus alternative splicing of pre-mRNA transcripts is a mechanism which leads to membrane expression of two forms of H-2Dd, one of which lacks a major site of phosphorylation. Images Fig. 1. Fig. 2. Fig. 4. PMID:3640710

  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. Solvent selection for the extraction of ethanol from aqueous solutions

    SciTech Connect

    Koullas, D.P.; Umealu, O.S.; Koukios, E.G.

    1999-08-01

    Several organic solvents were examined as potential separating agents for ethanol recovery from aqueous solutions by liquid-liquid extraction. Phase composition determinations for five promising ethanol-water-solvent systems at 20 and 40 C and two solvent-to-feed ratios show that isoamyl acetate (IAA) and isooctyl alcohol (IOA) along with n-butyl acetate (BA) present a greater potential than dibutyl ether and dibutyl oxalate. Tie-line liquid-liquid equilibrium data at 25 C for the three promising solvents (IAA, IOA, and BA) were collected and analyzed. Both IAA and IOA were found to be very good separating agents, exhibiting ethanol distribution coefficients greater than 1, and separation factors in Bancroft coordinates of the order of 70 and 2,000, respectively.

  14. Improved photobiological H2 production in engineered green algal cells.

    PubMed

    Kruse, Olaf; Rupprecht, Jens; Bader, Klaus-Peter; Thomas-Hall, Skye; Schenk, Peer Martin; Finazzi, Giovanni; Hankamer, Ben

    2005-10-01

    Oxygenic photosynthetic organisms use solar energy to split water (H2O) into protons (H+), electrons (e-), and oxygen. A select group of photosynthetic microorganisms, including the green alga Chlamydomonas reinhardtii, has evolved the additional ability to redirect the derived H+ and e- to drive hydrogen (H2) production via the chloroplast hydrogenases HydA1 and A2 (H2 ase). This process occurs under anaerobic conditions and provides a biological basis for solar-driven H2 production. However, its relatively poor yield is a major limitation for the economic viability of this process. To improve H2 production in Chlamydomonas, we have developed a new approach to increase H+ and e- supply to the hydrogenases. In a first step, mutants blocked in the state 1 transition were selected. These mutants are inhibited in cyclic e- transfer around photosystem I, eliminating possible competition for e- with H2ase. Selected strains were further screened for increased H2 production rates, leading to the isolation of Stm6. This strain has a modified respiratory metabolism, providing it with two additional important properties as follows: large starch reserves (i.e. enhanced substrate availability), and a low dissolved O2 concentration (40% of the wild type (WT)), resulting in reduced inhibition of H2ase activation. The H2 production rates of Stm6 were 5-13 times that of the control WT strain over a range of conditions (light intensity, culture time, +/- uncoupler). Typically, approximately 540 ml of H2 liter(-1) culture (up to 98% pure) were produced over a 10-14-day period at a maximal rate of 4 ml h(-1) (efficiency = approximately 5 times the WT). Stm6 therefore represents an important step toward the development of future solar-powered H2 production systems. PMID:16100118

  15. 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.

  16. Naloxone and ethanol intoxication.

    PubMed

    Askenasi, R; Fontaine, J

    1982-01-01

    Naloxone has been said to be an antidote of acute ethanol intoxication in man. Experimental and clinical studies are however not convincing and contradictory. We have used naloxone to antagonize the effect of ethanol in mice. Results are compared to those obtained with morphine intoxication. Even at high doses (5 mg/kg) naloxone is not a good antagonist of ethanol intoxication in mice.

  17. 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.

  18. 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

  19. 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...

  20. 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...

  1. 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

  2. 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.

  3. Enhanced ethanol catabolism in orphan nuclear receptor SHP-null mice.

    PubMed

    Park, Jung Eun; Lee, Mikang; Mifflin, Ryan; Lee, Yoon Kwang

    2016-05-15

    Deficiency of the orphan nuclear hormone receptor small heterodimer partner (SHP, NR0B2) protects mice from diet-induced hepatic steatosis, in part, via repression of peroxisome proliferator-activated receptor (PPAR)-γ2 (Pparg2) gene expression. Alcoholic fatty liver diseases (AFLD) share many common pathophysiological features with non-AFLD. To study the role of SHP and PPARγ2 in AFLD, we used a strategy of chronic ethanol feeding plus a single binge ethanol feeding to challenge wild-type (WT) and SHP-null (SHP(-/-)) mice with ethanol. The ethanol feeding induced liver fat accumulation and mRNA expression of hepatic Pparg2 in WT mice, which suggests that a high level of PPARγ2 is a common driving force for fat accumulation induced by ethanol or a high-fat diet. Interestingly, ethanol-fed SHP(-/-) mice displayed hepatic fat accumulation similar to that of ethanol-fed WT mice, even though their Pparg2 expression level remained lower. Mortality of SHP(-/-) mice after ethanol binge feeding was significantly reduced and their acetaldehyde dehydrogenase (Aldh2) mRNA level was higher than that of their WT counterparts. After an intoxicating dose of ethanol, SHP(-/-) mice exhibited faster blood ethanol clearance and earlier wake-up time than WT mice. Higher blood acetate, the end product of ethanol metabolism, and lower acetaldehyde levels were evident in the ethanol-challenged SHP(-/-) than WT mice. Ethanol-induced inflammatory responses and lipid peroxidation were also lower in SHP(-/-) mice. The current data show faster ethanol catabolism and extra fat storage through conversion of acetate to acetyl-CoA before its release into the circulation in this ethanol-feeding model in SHP(-/-) mice.

  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. 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.

  6. The 50 Ah NiH2 CPV qualification tests

    NASA Technical Reports Server (NTRS)

    Garner, J. C.; Barnes, Wilbert L.; Hickman, Gary L.

    1995-01-01

    In 1992, the Naval Research Laboratory (NRL) started a program to qualify a large diameter common pressure vessel (CPV) nickel-hydrogen (NiH2) batteries for use on future Navy/NRL spacecraft electrical power subsystems. NRL's involvement with the qualification of CPV NiH2 batteries dates back to 1988 when COMSAT and Johnson Controls, Inc. initiated a joint effort to fly the first ever NiH2 CPV in space. A later NRL-JCI cooperative research and development agreement led to the launch of a space experiment in 1993 and to the use of a single NiH2 CPV battery on the BMDO Clementine spacecraft in 1994. NRL initiated procurement of two, 50 Ah CPV NiH2 batteries in the Fall of 1992. The two batteries were delivered to NRL in June 1994. NiH2 CPV batteries have almost 2x the specific energy (Wh/kg) of nickel cadium batteries and 2x the energy density (Wh/l) of individual pressure vessel NiH2 CPV's. This presentation discusses the results of electrical and mechanical qualification tests conducted at NRL. The tests included electrical characterization, standard capacity, random vibration, peak load, and thermal vacuum. The last slides of the presentation show initial results from the life cycle tests of the second NiH2 CPV battery at 40% depth of discharge and a temperature of 10 C.

  7. 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.

  8. H2S, a novel gasotransmitter, involves in gastric accommodation

    PubMed Central

    Xiao, Ailin; Wang, Hongjuan; Lu, Xin; Zhu, Jianchun; Huang, Di; Xu, Tonghui; Guo, Jianqiang; Liu, Chuanyong; Li, Jingxin

    2015-01-01

    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. PMID:26531221

  9. 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.

  10. The 50 Ah NiH2 CPV qualification tests

    NASA Astrophysics Data System (ADS)

    Garner, J. C.; Barnes, Wilbert L.; Hickman, Gary L.

    1995-02-01

    In 1992, the Naval Research Laboratory (NRL) started a program to qualify a large diameter common pressure vessel (CPV) nickel-hydrogen (NiH2) batteries for use on future Navy/NRL spacecraft electrical power subsystems. NRL's involvement with the qualification of CPV NiH2 batteries dates back to 1988 when COMSAT and Johnson Controls, Inc. initiated a joint effort to fly the first ever NiH2 CPV in space. A later NRL-JCI cooperative research and development agreement led to the launch of a space experiment in 1993 and to the use of a single NiH2 CPV battery on the BMDO Clementine spacecraft in 1994. NRL initiated procurement of two, 50 Ah CPV NiH2 batteries in the Fall of 1992. The two batteries were delivered to NRL in June 1994. NiH2 CPV batteries have almost 2x the specific energy (Wh/kg) of nickel cadium batteries and 2x the energy density (Wh/l) of individual pressure vessel NiH2 CPV's. This presentation discusses the results of electrical and mechanical qualification tests conducted at NRL. The tests included electrical characterization, standard capacity, random vibration, peak load, and thermal vacuum. The last slides of the presentation show initial results from the life cycle tests of the second NiH2 CPV battery at 40% depth of discharge and a temperature of 10 C.

  11. Vibrational Predissociation Dynamics of the (H_2O)_2 Dimer

    NASA Astrophysics Data System (ADS)

    Ch'ng, L. C.; Rocher, B. E.; Mollner, A. K.; Reisler, H.

    2011-06-01

    The state-to-state vibrational predissociation dynamics of the (H_2O)_2 dimer were studied by resonance-enhanced multiphoton ionization (REMPI) and velocity-map imaging (VMI) to obtain pair-correlated product energy distributions. The 2+1 REMPI spectra of the H_2O photofragments were recorded via the tilde{C}^1B_1 (000) ← tilde{X}^1A_1 (000 and 010) transition following a vibrational excitation of the dimer's bound-OH stretch fundamental. The fragment' center-of-mass translational energy (c.m. E_T) distributions were determined from VMI of selected rotational states of the detected H_2O photofragments. The c.m. E_T distributions were then converted to pair-correlated H_2O cofragment rotational level distributions. This is the first experiment in which H_2O products with bend (ν_2) excitation were observed by REMPI. The dissociation energy of the dimer was determined from the images with spectroscopic accuracy. The predissociation mechanism of (H_2O)_2 will be discussed and compared with the corresponding hydrogen bonded dimers of an acid (HCl-H_2O) and a base (NH_3-H_2O).

  12. 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.

  13. Interaction of nutrition and binge ethanol treatment on brain damage and withdrawal.

    PubMed

    Crews, F T; Braun, C J; Ali, R; Knapp, D J

    2001-01-01

    To determine if nutrition plays a role in ethanol withdrawal and alcohol-induced brain damage, the effects of a 4-day ethanol binge treatment using ethanol in a nutritionally complete liquid diet compared to ethanol mixed with water were studied. The nutritionally complete diet group (ETOH-diet) received a complete diet of sugars, proteins and fats with vitamins and minerals with approximately 53% of calories from ethanol while the nutritionally deprived group (ETOH-H2O) received 100% of calories from ethanol. No difference in withdrawal behavior was found between the ETOH-diet and ETOH-H2O groups during the 72-hour period studied. In addition, no difference was seen for serum levels of magnesium and zinc taken at last dose or following 72 h of withdrawal. Serum alanine aminotransferase (ALT) and ammonia were increased in both groups with ETOH-diet showing a greater increase in ALT than ETOH-H2O. Both groups showed damage in the olfactory bulb, perirhinal, agranular insular, piriform and lateral entorhinal cortical areas as well as hippocampal dentate gyrus and CA-3. Interestingly, the ETOH-diet group displayed more damage at last dose in the posterior dentate and CA-3 of hippocampus than did the ETOH-H2O group. This study suggests that nutritional components and total caloric intake do not effect behavior during ethanol withdrawal and that a nutritionally complete diet may increase ethanol-induced brain damage.

  14. Scavenging of H2O2 by mouse brain mitochondria.

    PubMed

    Starkov, Anatoly A; Andreyev, Alexander Yu; Zhang, Steven F; Starkova, Natalia N; Korneeva, Maria; Syromyatnikov, Mikhail; Popov, Vasily N

    2014-12-01

    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.

  15. Detection of a new interstellar molecule, H2CN

    NASA Technical Reports Server (NTRS)

    Ohishi, Masatoshi; Mcgonagle, Douglas; Irvine, William M.; Yamamoto, Satoshi; Saito, Shuji

    1994-01-01

    We have detected a new interstellar molecule, H2CN (methylene amidogen), in the cold, dark molecular cloud TMC-1. The column density of H2CN is estimated to be approximately 1.5 x 10(exp 11) cm(exp -2) by assuming an excitation temperature of 5 K. This column density corresponds to a fractional abundance relative to H2 of approximately 1.5 x 10(exp -11). This value is more than three orders of magnitude less than the abundance of the related molecule HCN in TMC-1. We also report a tentative detection of H2CN in Sgr B2(N). The formation mechanism of H2CN is discussed. Our detection of the N2CN molecule may suggest the existence of a new series of carbon-chain molecules, CH2C(n)N (N = 0, 1, 2, ...).

  16. Hormetic Effect of H2O2 in Saccharomyces cerevisiae

    PubMed Central

    Valishkevych, Bohdana V.

    2016-01-01

    In this study, we investigated the relationship between target of rapamycin (TOR) and H2O2-induced hormetic response in the budding yeast Saccharomyces cerevisiae grown on glucose or fructose. In general, our data suggest that: (1) hydrogen peroxide (H2O2) induces hormesis in a TOR-dependent manner; (2) the H2O2-induced hormetic dose–response in yeast depends on the type of carbohydrate in growth medium; (3) the concentration-dependent effect of H2O2 on yeast colony growth positively correlates with the activity of glutathione reductase that suggests the enzyme involvement in the H2O2-induced hormetic response; and (4) both TOR1 and TOR2 are involved in the reciprocal regulation of the activity of glucose-6-phosphate dehydrogenase and glyoxalase 1. PMID:27099601

  17. Polysulfides Link H2S to Protein Thiol Oxidation

    PubMed Central

    Greiner, Romy; Pálinkás, Zoltán; Bäsell, Katrin; Becher, Dörte; Antelmann, Haike; Nagy, Péter

    2013-01-01

    Abstract Aims: Hydrogen sulfide (H2S) is suggested to act as a gaseous signaling molecule in a variety of physiological processes. Its molecular mechanism of action was proposed to involve protein S-sulfhydration, that is, conversion of cysteinyl thiolates (Cys-S−) to persulfides (Cys-S-S−). A central and unresolved question is how H2S—that is, a molecule with sulfur in its lowest possible oxidation state (−2)—can lead to oxidative thiol modifications. Results: Using the lipid phosphatase PTEN as a model protein, we find that the “H2S donor” sodium hydrosulfide (NaHS) leads to very rapid reversible oxidation of the enzyme in vitro. We identify polysulfides formed in NaHS solutions as the oxidizing species, and present evidence that sulfane sulfur is added to the active site cysteine. Polysulfide-mediated oxidation of PTEN was induced by all “H2S donors” tested, including sodium sulfide (Na2S), gaseous H2S, and morpholin-4-ium 4-methoxyphenyl(morpholino) phosphinodithioate (GYY4137). Moreover, we show that polysulfides formed in H2S solutions readily modify PTEN inside intact cells. Innovation: Our results shed light on the previously unresolved question of how H2S leads to protein thiol oxidation, and suggest that polysulfides formed in solutions of H2S mediate this process. Conclusion: This study suggests that the effects that have been attributed to H2S in previous reports may in fact have been mediated by polysulfides. It also supports the notion that sulfane sulfur rather than sulfide is the actual in vivo agent of H2S signaling. Antioxid. Redox Signal. 19, 1749–1765. PMID:23646934

  18. 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. PMID:20553937

  19. 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.

  20. Transcriptome shifts in response to furfural and acetic acid in Saccharomyces cerevisiae.

    PubMed

    Li, Bing-Zhi; Yuan, Ying-Jin

    2010-05-01

    Furfural and acetic acid are two prevalent inhibitors to microorganisms during cellulosic ethanol production, but molecular mechanisms of tolerance to these inhibitors are still unclear. In this study, genome-wide transcriptional responses to furfural and acetic acid were investigated in Saccharomyces cerevisiae using microarray analysis. We found that 103 and 227 genes were differentially expressed in the response to furfural and acetic acid, respectively. Furfural downregulated genes related to transcriptional control and translational control, while it upregulated stress-responsive genes. Furthermore, furfural also interrupted the transcription of genes involved in metabolism of essential chemicals, such as etrahydrofolate, spermidine, spermine, and riboflavin monophosphate. Acetic acid downregulated genes encoding mitochondrial ribosomal proteins and genes involved in carbohydrate metabolism and regulation and upregulated genes related to amino acid metabolism. The results revealed that furfural and acetic acid had effects on multiple aspects of cellular metabolism on the transcriptional level and that mitochondria might play important roles in response to both furfural and acetic acid. This research has provided insights into molecular response to furfural and acetic acid in S. cerevisiae, and it will be helpful to construct more resistant strains for cellulosic ethanol production.

  1. 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

  2. Autophagy and ethanol neurotoxicity

    PubMed Central

    Luo, Jia

    2015-01-01

    Excessive ethanol exposure is detrimental to the brain. The developing brain is particularly vulnerable to ethanol such that prenatal ethanol exposure causes fetal alcohol spectrum disorders (FASD). Neuronal loss in the brain is the most devastating consequence and is associated with mental retardation and other behavioral deficits observed in FASD. Since alcohol consumption during pregnancy has not declined, it is imperative to elucidate the underlying mechanisms and develop effective therapeutic strategies. One cellular mechanism that acts as a protective response for the central nervous system (CNS) is autophagy. Autophagy regulates lysosomal turnover of organelles and proteins within cells, and is involved in cell differentiation, survival, metabolism, and immunity. We have recently shown that ethanol activates autophagy in the developing brain. The autophagic preconditioning alleviates ethanol-induced neuron apoptosis, whereas inhibition of autophagy potentiates ethanol-stimulated reactive oxygen species (ROS) and exacerbates ethanol-induced neuroapoptosis. The expression of genes encoding proteins required for autophagy in the CNS is developmentally regulated; their levels are much lower during an ethanol-sensitive period than during an ethanol-resistant period. Ethanol may stimulate autophagy through multiple mechanisms; these include induction of oxidative stress and endoplasmic reticulum stress, modulation of MTOR and AMPK signaling, alterations in BCL2 family proteins, and disruption of intracellular calcium (Ca2+) homeostasis. This review discusses the most recent evidence regarding the involvement of autophagy in ethanol-mediated neurotoxicity as well as the potential therapeutic approach of targeting autophagic pathways. PMID:25484085

  3. 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.

  4. TES/Aura L2 Water Vapor (H2O) Lite Nadir (TL2H2OLN)

    Atmospheric Science Data Center

    2015-06-16

    TES/Aura L2 Water Vapor (H2O) Lite Nadir (TL2H2OLN) News:  TES News ... Level:  L2 Instrument:  TES/Aura L2 Water Vapor Spatial Coverage:  5.3 km nadir ... HDFView Read Software Level 2 Google Earth Visualizations Related Data:  Level 2 Lite Survey ...

  5. Central histaminergic transmission modulates the ethanol induced anxiolysis in mice.

    PubMed

    Verma, Lokesh; Jain, Nishant S

    2016-10-15

    Intrigued by the report demonstrating an increase in brain histamine levels by ethanol administration and central histamine transmission to affect the anxiety related behaviors, the present study examined the permissive role of central histaminergic transmission in the acute anxiolytic-like effect of the ethanol on elevated plus maze (EPM) in mice. Results demonstrated that prior administration of the agents that are known to enhance the brain histamine transmission, i.e. low dose of histamine (0.1μg/mouse, i.c.v.) or histamine precursor, l-histidine (500, 1000mg/kg, i.p.) or low dose of histamine releasing agent (H3 receptor inverse agonist), thioperamide (2μg/mouse) attenuated the acute anitanxiety-like effect of ethanol (2g/kg, i.p, 8% w/v) in mice on EPM. However, pre-treatment with the H1 receptor antagonist, cetirizine (0.1μg/mouse, i.c.v.) or H2 receptor antagonist, ranitidine (50μg/mouse, i.c.v.) failed to affect the attenuating effect of low dose of histamine on ethanol induced anxiolysis. On the other hand, only H1 receptor antagonist, cetirizine (0.1μg/mouse, i.c.v.) was able to partially reverse the attenuation of ethanol induced anxiolysis by l-histidine (1000mg/kg, i.p.). Surprisingly, in mice pre-treated with the higher dose of histamine (50μg/mouse, i.c.v.) or thioperamide (10μg/mouse, i.c.v.), the ethanol (2g/kg, i.p.) induced antianxiety-like effect was further enhanced on EPM. Furthermore, this potentiating effect of high dose of histamine on the ethanol (2g/kg, i.p.) was exacerbated on pre-treatment with the H1 receptor antagonist, cetirizine, while H2 receptor antagonist, ranitidine completely reversed this action of high dose of histamine on ethanol. Supportive to these results, i.c.v. pre-treatment with H1 receptor agonist, FMPH (2, 6.5μg/mouse, i.c.v.) attenuated while H2 receptor agonist, amthamine (0.1, 0.5μg/mouse, i.c.v.) enhanced the ethanol induced anxiolysis in mice. Thus, it is reasonable to contemplate that central

  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. 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. Mode specificity in the H + H2O → H2 + OH reaction: A full-dimensional quantum dynamics study

    NASA Astrophysics Data System (ADS)

    Fu, Bina; Zhang, Dong H.

    2013-05-01

    The initial state-selected time-dependent wave packet approach to an atom-triatom reaction is employed to study the H + H2O → H2 + OH reaction without the centrifugal sudden approximation. The total reaction probabilities and integral cross sections, which are the exact coupled-channel results, are calculated for the H2O reactant initially in the ground and several vibrationally excited states, including bending excited states, first and second stretching excited states, and simultaneous excitations of both bending and stretching modes. The reactivity enhancements from different initial states of the H2O reagent are presented and discussed in detail. The thermal rate constant for the title reaction and the contributions to this coefficient from individual vibrational states of H2O are also obtained and compared with the previous theoretical and experimental data.

  9. 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.

  10. Analytic H i-to-H2 Photodissociation Transition Profiles

    NASA Astrophysics Data System (ADS)

    Bialy, Shmuel; Sternberg, Amiel

    2016-05-01

    We present a simple analytic procedure for generating atomic (H i) to molecular ({{{H}}}2) density profiles for optically thick hydrogen gas clouds illuminated by far-ultraviolet radiation fields. Our procedure is based on the analytic theory for the structure of one-dimensional H i/{{{H}}}2 photon-dominated regions, presented by Sternberg et al. Depth-dependent atomic and molecular density fractions may be computed for arbitrary gas density, far-ultraviolet field intensity, and the metallicity-dependent H2 formation rate coefficient, and dust absorption cross section in the Lyman–Werner photodissociation band. We use our procedure to generate a set of {{H}} {{I}}{-}{to}{-}{{{H}}}2 transition profiles for a wide range of conditions, from the weak- to strong-field limits, and from super-solar down to low metallicities. We show that if presented as functions of dust optical depth, the {{H}} {{I}} and {{{H}}}2 density profiles depend primarily on the Sternberg “α G parameter” (dimensionless) that determines the dust optical depth associated with the total photodissociated {{H}} {{I}} column. We derive a universal analytic formula for the {{H}} {{I}}{-}{to}{-}{{{H}}}2 transition points as a function of just α G. Our formula will be useful for interpreting emission-line observations of H i/{{{H}}}2 interfaces, for estimating star formation thresholds, and for sub-grid components in hydrodynamics simulations.

  11. Analytic H i-to-H2 Photodissociation Transition Profiles

    NASA Astrophysics Data System (ADS)

    Bialy, Shmuel; Sternberg, Amiel

    2016-05-01

    We present a simple analytic procedure for generating atomic (H i) to molecular ({{{H}}}2) density profiles for optically thick hydrogen gas clouds illuminated by far-ultraviolet radiation fields. Our procedure is based on the analytic theory for the structure of one-dimensional H i/{{{H}}}2 photon-dominated regions, presented by Sternberg et al. Depth-dependent atomic and molecular density fractions may be computed for arbitrary gas density, far-ultraviolet field intensity, and the metallicity-dependent H2 formation rate coefficient, and dust absorption cross section in the Lyman-Werner photodissociation band. We use our procedure to generate a set of {{H}} {{I}}{-}{to}{-}{{{H}}}2 transition profiles for a wide range of conditions, from the weak- to strong-field limits, and from super-solar down to low metallicities. We show that if presented as functions of dust optical depth, the {{H}} {{I}} and {{{H}}}2 density profiles depend primarily on the Sternberg “α G parameter” (dimensionless) that determines the dust optical depth associated with the total photodissociated {{H}} {{I}} column. We derive a universal analytic formula for the {{H}} {{I}}{-}{to}{-}{{{H}}}2 transition points as a function of just α G. Our formula will be useful for interpreting emission-line observations of H i/{{{H}}}2 interfaces, for estimating star formation thresholds, and for sub-grid components in hydrodynamics simulations.

  12. Evaluation of the tolerance of acetic acid and 2-furaldehyde on the growth of Pichia stipitis and its respiratory deficient.

    PubMed

    Ortiz-Muñiz, B; Rasgado-Mellado, J; Solis-Pacheco, J; Nolasco-Hipólito, C; Domínguez-González, J M; Aguilar-Uscanga, M G

    2014-10-01

    The use of lignocellulosic residues for ethanol production is limited by toxic compounds in fermenting yeasts present in diluted acid hydrolysates like acetic acid and 2-furaldehyde. The respiratory deficient phenotype gives the cell the ability to resist several toxic compounds. So the aim of this work was to evaluate the tolerance to toxic compounds present in lignocellulosic hydrolysates like acetic acid and 2-furaldehyde in Pichia stipitis and its respiratory deficient strains. The respiratory deficient phenotype was induced by exposure to chemical agents such as acriflavine, acrylamide and rhodamine; 23 strains were obtained. The selection criterion was based on increasing specific ethanol yield (g ethanol g(-1) biomass) with acetic acid and furaldehyde tolerance. The screening showed that P. stipitis NRRL Y-7124 ACL 2-1RD (lacking cytochrome c), obtained using acrylamide, presented the highest specific ethanol production rate (1.82 g g(-1 )h(-1)). Meanwhile, the ACF8-3RD strain showed the highest acetic acid tolerance (7.80 g L(-1)) and the RHO2-3RD strain was able to tolerate up to 1.5 g L(-1) 2-furaldehyde with a growth and ethanol production inhibition of 23 and 22 %, respectively. The use of respiratory deficient yeast phenotype is a strategy for ethanol production improvement in a medium with toxic compounds such as hydrolysed sugarcane bagasse amongst others.

  13. 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. PMID:17721788

  14. Novel anthracene-based fluorescent sensor for selective recognition of acetate anions in protic media

    NASA Astrophysics Data System (ADS)

    Xu, Kuoxi; Kong, Huajie; Li, Qian; Song, Pan; Dai, Yanpeng; Yang, Li

    2015-02-01

    Novel 9-substituted anthracene derivatives were synthesized and characterized by IR, HRMS, 1H and 13C NMR. The fluorescence titration experiments were explored to study the interaction between the compounds and some anions, such as H2PO4-, P2O74-, F-, Cl-, Br-, I-, AcO- in H2O (0.01 M HEPES, pH = 7.4) under imitated physiological conditions. One of these compounds, bearing a phenylalaninol unit, showed specific fluorescence enhancement with acetate anion. The sensor L1 was found to present good selective fluorescence sensing ability to acetate anion through photoinduced electron-transfer mechanism in protic media.

  15. Modeling the H2O submillimeter emission in extragalactic sources

    NASA Astrophysics Data System (ADS)

    González-Alfonso, E.; Fischer, J.; Aalto, S.; Falstad, N.

    2014-07-01

    Recent observational studies have shown that H2O emission at (rest) submillimeter wavelengths is ubiquitous in infrared galaxies, both in the local and in the early Universe, suggestive of far-infrared pumping of H2O by dust in warm regions. In this work, models are presented that show that (i) the highest-lying H2O lines (Eupper > 400 K) are formed in very warm (Tdust ≳ 90 K) regions and require high H2O columns (NH2O ≳ 3 × 1017 cm-2), while lower lying lines can be efficiently excited with Tdust ~ 45-75 K and NH2O ~ (0.5-2) × 1017 cm-2; (ii) significant collisional excitation of the lowest lying (Eupper < 200 K) levels, which enhances the overall LH2O-LIR ratios, is identified in sources where the ground-state para-H2O 111-000 line is detected in emission; (iii) the H2O-to-infrared (8-1000 μm) luminosity ratio is expected to decrease with increasing Tdust for all lines with Eupper ≲ 300 K, as has recently been reported in a sample of LIRGs, but increases with Tdust for the highest lying H2O lines (Eupper > 400 K); (iv) we find theoretical upper limits for LH2O/LIR in warm environments, owing to H2O line saturation; (v) individual models are presented for two very different prototypical galaxies, the Seyfert 2 galaxy NGC 1068 and the nearest ultraluminous infrared galaxy Arp 220, showing that the excited submillimeter H2O emission is dominated by far-infrared pumping in both cases; (vi) the LH2O - LIR correlation previously reported in observational studies indicates depletion or exhaustion time scales, tdep = Σgas/ ΣSFR, of ≲12 Myr for star-forming sources where lines up to Eupper = 300 K are detected, in agreement with the values previously found for (U)LIRGs from HCN millimeter emission. We conclude that the submillimeter H2O line emission other than the para-H2O 111-000 transition is pumped primarily by far-infrared radiation, though some collisional pumping may contribute to the low-lying para-H2O 202-111 line, and that collisional pumping of the

  16. Phase diagram and thermodynamic properties of H2.

    PubMed

    Osman, S M; Ali, I; Singh, R N

    2013-01-01

    A statistical mechanical-based theory is used to develop the equation of state for the molecular fluid of H(2). We incorporate in this equation the long-range correlations through the double Yukawa potential, dimerization of the H(2) molecule by treating the fluid as a hard convex body fluid, and first-order quantum correction which is important at low temperatures. We use this to calculate the liquid-vapor equilibrium of H(2), including the temperature and pressure dependence of compressibility factor, entropy, specific heat, compressibility, and sound velocity. PMID:23410298

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  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. 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.

  3. Maleic acid solvation in mixed water-ethanol solvents

    NASA Astrophysics Data System (ADS)

    Usacheva, T. R.; Kuz'mina, I. A.; Sharnin, V. A.; Tukumova, I. R.

    2012-04-01

    Heat effects of maleic acid dissolution in mixed water-ethanol solvents at 298.15 K are determined by means of calorimetry. A rise in exothermicity of maleic acid solvation is observed upon changes in the solvent copmosition in the direction of H2O → EtOH, the minimum being at ˜0.2 mol fraction of EtOH.

  4. Acetate induced enhancement of photocatalytic hydrogen peroxide production from oxalic acid and dioxygen.

    PubMed

    Yamada, Yusuke; Nomura, Akifumi; Miyahigashi, Takamitsu; Ohkubo, Kei; Fukuzumi, Shunichi

    2013-05-01

    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.

  5. Enhanced photocatalytic H2-production activity of graphene-modified titania nanosheets

    NASA Astrophysics Data System (ADS)

    Xiang, Quanjun; Yu, Jiaguo; Jaroniec, Mietek

    2011-09-01

    Graphene-modified TiO2 nanosheets with exposed (001) facets (graphene/TiO2) were prepared by microwave-hydrothermal treatment of graphene oxide (GO) and hydrothermally synthesized TiO2 nanosheets with exposed (001) facets in an ethanol-water solvent. These nanocomposite samples showed high photocatalytic H2-production activity in aqueous solutions containing methanol, as sacrificial reagent, even without Pt co-catalyst. The optimal graphene content was found to be ~1.0 wt%, giving a H2-production rate of 736 μmol h-1 g-1 with a quantum efficiency (QE) of 3.1%, which exceeded the rate observed on pure TiO2 nanosheets by more than 41 times. This high photocatalytic H2-production activity is due to the deposition of TiO2 nanosheets on graphene sheets, which act as an electron acceptor to efficiently separate the photogenerated charge carriers. The observed enhancement in the photocatalytic activity is due to the lower absolute potential of graphene/graphene z.rad- (-0.08 V vs. SHE, pH = 0) in comparison to the conduction band (-0.24 V) of anatase TiO2, meanwhile the aforementioned absolute value is higher than the reduction potential of H+ (0 V), which favors the electron transfer from the conduction band (CB) of TiO2 to graphene sheets and the reduction of H+, thus enhancing photocatalytic H2-production activity. The proposed mechanism for the observed photocatalytic performance of TiO2 nanosheets, modified with a small amount of graphene, was further confirmed by photoluminescence spectroscopy and transient photocurrent response. This work not only shows a possibility for the utilization of low cost graphene sheets as a substitute for noble metals (such as Pt) in the photocatalytic H2-production but also for the first time shows a significant enhancement in the H2-production activity by using metal-free carbon material as an effective co-catalyst.

  6. 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.

  7. Quantum magnetic deflagration in acetate.

    PubMed

    Hernández-Mínguez, A; Hernandez, J M; Macià, F; García-Santiago, A; Tejada, J; Santos, P V

    2005-11-18

    We report controlled ignition of magnetization reversal avalanches by surface acoustic waves in a single crystal of acetate. Our data show that the speed of the avalanche exhibits maxima on the magnetic field at the tunneling resonances of Mn(12). Combined with the evidence of magnetic deflagration in Mn(12) acetate, this suggests a novel physical phenomenon: deflagration assisted by quantum tunneling. PMID:16384178

  8. Quantum magnetic deflagration in acetate.

    PubMed

    Hernández-Mínguez, A; Hernandez, J M; Macià, F; García-Santiago, A; Tejada, J; Santos, P V

    2005-11-18

    We report controlled ignition of magnetization reversal avalanches by surface acoustic waves in a single crystal of acetate. Our data show that the speed of the avalanche exhibits maxima on the magnetic field at the tunneling resonances of Mn(12). Combined with the evidence of magnetic deflagration in Mn(12) acetate, this suggests a novel physical phenomenon: deflagration assisted by quantum tunneling.

  9. 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.

  10. The role of H2S bioavailability in endothelial dysfunction.

    PubMed

    Wang, Rui; Szabo, Csaba; Ichinose, Fumito; Ahmed, Asif; Whiteman, Matthew; Papapetropoulos, Andreas

    2015-09-01

    Endothelial dysfunction (EDF) reflects pathophysiological changes in the phenotype and functions of endothelial cells that result from and/or contribute to a plethora of cardiovascular diseases. We review the role of hydrogen sulfide (H2S) in the pathogenesis of EDF, one of the fastest advancing research topics. Conventionally treated as an environment pollutant, H2S is also produced in endothelial cells and participates in the fine regulation of endothelial integrity and functions. Disturbed H2S bioavailability has been suggested to be a novel indicator of EDF progress and prognosis. EDF manifests in different forms in multiple pathologies, but therapeutics aimed at remedying altered H2S bioavailability may benefit all. PMID:26071118

  11. The role of H2S bioavailability in endothelial dysfunction

    PubMed Central

    Wang, Rui; Szabo, Csaba; Ichinose, Fumito; Ahmed, Asif; Whiteman, Matthew; Papapetropoulos, Andreas

    2015-01-01

    Endothelial dysfunction reflects pathophysiological changes in the phenotype and functions of endothelial cells that result from and/or contribute to a plethora of cardiovascular diseases. Here we review the role of hydrogen sulfide (H2S) in the pathogenesis of endothelial dysfunction, one of the fastest advanced and hottest research topics. Conventionally treated as an environment pollutant, H2S is also produced in endothelial cells and participates in the fine regulation of endothelial integrity and functions. Disturbed H2S bioavailability has been suggested to be a novel indicator of the progress and prognosis of endothelial dysfunction. Endothelial dysfunction appears to exhibit in different forms in different pathologies but therapeutics aimed at remedying the altered H2S bioavailability may benefit all. PMID:26071118

  12. Synthesis and crystal structure of the lithium perrhenate monohydrate LiReO 4·H 2O

    NASA Astrophysics Data System (ADS)

    Abakumov, Artem M.; Rozova, Marina G.; Shpanchenko, Roman V.; Mironov, Andrei V.; Antipov, Evgeny V.; Bramnik, Kirill G.

    2001-07-01

    A new monohydrate of lithium perrhenate LiReO 4·H 2O was prepared by dehydration of LiReO 4·1.5H 2O at room temperature. The single crystals of LiReO 4·H 2O were obtained by crystallisation from the isoamyl acetate solution of LiReO 4·1.5H 2O. The structure of monohydrate ( a=5.6674(4), b=10.771(1), c=7.4738(7) Å, β=102.422(7)°, R1=0.0414, space group P2 1/ a, Z=4) is built up from LiO 3(H 2O) 2 trigonal bipyramids and ReO 4 tetrahedra sharing common edges and corners inside the layers. The layers are connected together by hydrogen bonds. The relationships between the structures of sesquihydrate, monohydrate and anhydrous LiReO 4 are discussed.

  13. Glycine Cleavage Powers Photoheterotrophic Growth of Chloroflexus aurantiacus in the Absence of H2

    PubMed Central

    He, Lian; Wang, Yaya; You, Le; Khin, Yadana; Tang, Joseph K.-H.; Tang, Yinjie J.

    2015-01-01

    Chloroflexus aurantiacus is an anoxygenic phototrophic bacterium. Its unique CO2 fixation pathway and primitive light-harvesting antenna complexes have attracted extensive research attentions. In this work, we investigated the photoheterotrophic growth of C. aurantiacus J-10-fl using acetate [at 55°C and without H2(g)]. The results indicate that glycine can promote anaerobic biomass production in a minimal medium by threefold to fivefold. Via 13C-metabolite analysis, we observed that glycine was involved in serine synthesis. Instead of being used as a major carbon source, glycine was degraded to produce C1 units and NAD(P)H. Tracer experiments also suggest that photoheterotrophic cultures growing with a exogenous glycine source exhibited capabilities of assimilating CO2 via multiple routes (including the 3-hydroxypropionate pathway). Finally, glycylglycine, a commonly used culture buffer, also significantly enhanced photoheterotrophic growth of C. aurantiacus, probably due to its thermal or enzymatic breakdown to glycine. PMID:26732979

  14. A comparison of ice VII formed in the H2O, NaCl-H2O, and CH3OH-H2O systems: Implications for H2O-rich planets

    NASA Astrophysics Data System (ADS)

    Frank, Mark R.; Aarestad, Elizabeth; Scott, Henry P.; Prakapenka, Vitali B.

    2013-02-01

    High-pressure H2O polymorphs, namely ice VI, ice VII, and ice X, are hypothesized to make up a considerable portion of the interiors of large icy satellites and select extra-solar planets. The incorporation of foreign ions or molecules into these high-pressure phases is possible through ocean-ice interaction, rock-ice interaction at depth, or processes that occurred during accretion. Recent research concerning the effects charged ions have on ice VII has shown that these ions notably affect the structure of ice VII (Frank et al., 2006; Klotz et al., 2009). This study was designed to determine the effects of a molecular impurity on ice VII and compare those effects to both pure H2O ice and ice with an ionic impurity. Ice samples were formed in this study via compression in a diamond anvil cell from either H2O, a 1.60 mol% NaCl aqueous solution, a 1.60 mol% CH3OH aqueous solution, or a 5.00 mol% CH3OH aqueous solution and were compressed up to 71 GPa at room temperature. Ice formed from pure H2O had no impurities whereas ices formed in the NaCl-H2O and CH3OH-H2O systems contained the impurities Na+ and Cl- and CH3OH, respectively. Pressure-volume relations were observed in situ by using synchrotron based X-ray diffraction and were used to determine the equations of state for ices formed in the H2O, NaCl-H2O and CH3OH-H2O systems. The data illustrate that ice VII formed from a NaCl-bearing aqueous solution exhibited a depressed volume when compared to that of H2O-only ice VII at any given pressure, whereas ice VII formed from CH3OH-bearing aqueous solutions showed an opposite trend, with an increase in volume relative to that of pure ice VII. The ices within planetary bodies will most likely have both ionic and molecular impurities and the trends outlined in this study can be used to improve density profiles of H2O-rich planetary bodies.

  15. 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.

  16. 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.

  17. Phase transition in the H2O-H2 system at pressures up to 10 kbar

    NASA Astrophysics Data System (ADS)

    Efimchenko, V.; Kuzovnikov, M.; Tkacz, M.

    2013-09-01

    Phase relations in the H2O-H2 system are of significant interest for planetary science because hydrogen and water are among the basic building materials of outer planets and their satellites. In 1993 [1], an investigation of the H2O-H2 system in the pressure interval 7.7 to 300 kbar revealed the occurrence of two crystalline hydrogen hydrates: the rhombohedral C1 phase, stable at pressures up to 25.5 kbar, and cubic C2 phase stable at higher pressures. An X-ray diffraction study of the C1 phase at 21 kbar and 22ºC showed the structure of its water sublattice to be similar to the rhombohedral structure of high-pressure ice II. On the basis of results of Raman studies, the molar ratio H2/H2O of the C1 phase was assumed to be invariable at pressures 7.7-25.5 kbar and equal to 1/6 that corresponds to 1.7 wt.% H2. Later, in the year of 1999, a cubic clathrate hydrate sII was found to form in the H2O-H2 system at pressures from 1.0-3.6 kbar [2]. Further investigations established the crystal structure of this hydrate [3] and the boundaries of its stability in composition [3] and pressure and temperature [4]. Our recent studies revealed the formation of a new trigonal phase called С0 [5] at a hydrogen pressure of 5 kbar. In the present work, using volumetric technique, we constructed the boundaries of the T-P stability region of the C0 phase and estimated the changes of the hydrogen content of ice accompanying the C0→C1 phase transition.

  18. 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.

  19. 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.

  20. Al-TiH2 Composite Foams Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Prasada Rao, A. K.; Oh, Y. S.; Ain, W. Q.; A, Azhari; Basri, S. N.; Kim, N. J.

    2016-02-01

    The work presented here in describes the synthesis of aluminum based titanium-hydride particulate composite by casting method and its foaming behavior of magnesium alloy. Results obtained indicate that the Al-10TiH2 composite can be synthesized successfully by casting method. Further, results also reveal that closed-cell magnesium alloy foam can be synthesized by using Al-10TiH2 composite as a foaming agent.

  1. 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.

  2. The interstellar chemistry of H2C3O isomers

    NASA Astrophysics Data System (ADS)

    Loison, Jean-Christophe; Agúndez, Marcelino; Marcelino, Núria; Wakelam, Valentine; Hickson, Kevin M.; Cernicharo, José; Gerin, Maryvonne; Roueff, Evelyne; Guélin, Michel

    2016-03-01

    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.

  3. 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

  4. 26 CFR 25.2523(h)-2 - Effective dates.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 14 2011-04-01 2010-04-01 true Effective dates. 25.2523(h)-2 Section 25.2523(h... TAXES GIFT TAX; GIFTS MADE AFTER DECEMBER 31, 1954 Deductions § 25.2523(h)-2 Effective dates. Except as... §§ 25.2523(e)-1(c), 25.2523(f)-1, 25.2523(g)-1, and 25.2523(h)-1 are effective with respect to...

  5. Microalgae: a green source of renewable H(2).

    PubMed

    Ghirardi, M L; Zhang, L; Lee, J W; Flynn, T; Seibert, M; Greenbaum, E; Melis, A

    2000-12-01

    This article summarizes recent advances in the field of algal hydrogen production. Two fundamental approaches are being developed. One involves the temporal separation of the usually incompatible reactions of O(2) and H(2) production in green algae, and the second involves the use of classical genetics to increase the O(2) tolerance of the reversible hydrogenase enzyme. The economic and environmental impact of a renewable source of H(2) are also discussed. PMID:11102662

  6. 26 CFR 25.2523(h)-2 - Effective dates.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 14 2010-04-01 2010-04-01 false Effective dates. 25.2523(h)-2 Section 25.2523(h... TAXES GIFT TAX; GIFTS MADE AFTER DECEMBER 31, 1954 Deductions § 25.2523(h)-2 Effective dates. Except as... §§ 25.2523(e)-1(c), 25.2523(f)-1, 25.2523(g)-1, and 25.2523(h)-1 are effective with respect to...

  7. 26 CFR 31.3406(h)-2 - Special rules.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 15 2010-04-01 2010-04-01 false Special rules. 31.3406(h)-2 Section 31.3406(h... Collection of Income Tax at Source § 31.3406(h)-2 Special rules. (a) Joint accounts—(1) Relevant name and... subject to the penalty under section 6705 (failure of a broker to provide notice to a payor). (h) To...

  8. Increase in peroxisome number and the gene expression of putative glyoxysomal enzymes in Chlamydomonas cells supplemented with acetate.

    PubMed

    Hayashi, Yasuko; Sato, Nagisa; Shinozaki, Akiko; Watanabe, Mariko

    2015-01-01

    We cultured Chlamydomonas reinhardtii cells in a minimal culture medium supplemented with various concentrations of acetate, fatty acids, ethanol, fatty alcohols, or sucrose. The presence of acetate (0.5 or 1.0%, w/v) was advantageous for cell growth. To determine whether peroxisomes are involved in fatty acid and fatty alcohol metabolism, we investigated the dynamics of peroxisomes, including changes in their number and size, in the presence of acetate, ethanol, and sucrose. The total volume of peroxisomes increased when cells were grown with acetate, but did not change when cells were grown with ethanol or sucrose. We analyzed cell growth on minimal culture medium supplemented with various fatty acids (carbon chain length ranging from one to ten) to investigate which fatty acids are metabolized by C. reinhardtii. Among them, acetate caused the greatest increase in growth when added to minimal culture media. We analyzed the transcript levels of genes encoding putative glyoxysomal enzymes. The transcript levels of genes encoding malate synthase, malate dehydrogenase, isocitrate lyase, and citrate synthase increased when Chlamydomonas cells were grown on minimal culture medium supplemented with acetate. Our results suggest that Chlamydomonas peroxisomes are involved in acetate metabolism via the glyoxylate cycle.

  9. 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.

  10. 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.

  11. 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

  12. Observations of H2S toward OMC-1.

    PubMed

    Minh, Y C; Ziurys, L M; Irvine, W M; McGonagle, D

    1990-09-01

    Interstellar hydrogen sulfide (H2S) and its isotopic variant (H2(34)S) have been observed toward several positions in OMC-1 via their 1(10)-1(01) transitions near 168 GHz using the FCRAO 14 m telescope. We derive total column densities toward Orion(KL) for the extended ridge, for the plateau, and for the hot core, in addition to values for other positions in OMC-1. The fractional abundance of H2S (approximately 10(-9)) in the quiescent regions of OMC-1 seems to be difficult to explain by currently known ion-molecule 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. This enhancement may be a result of grain surface chemistry and/or of high-temperature gas-phase chemistry. From the nondetection of HDS in its 2(11)-2(12) transition, we estimate the abundance ratio [HDS]/H2S] < or = 0.02 in the hot core.

  13. Hydrogen Storage Properties of New Hydrogen-Rich BH3NH3-Metal Hydride (TiH2, ZrH2, MgH2, and/or CaH2) Composite Systems

    SciTech Connect

    Choi, Young Joon; Xu, Yimin; Shaw, Wendy J.; Ronnebro, Ewa

    2012-04-19

    Ammonia borane (AB = NH3BH3) is one of the most attractive materials for chemical hydrogen storage due to its high hydrogen contents of 19.6 wt.%, however, impurity levels of borazine, ammonia and diborane in conjunction with foaming and exothermic hydrogen release calls for finding ways to mitigate the decomposition reactions. In this paper we present a solution by mixing AB with metal hydrides (TiH2, ZrH2, MgH2 and CaH2) which have endothermic hydrogen release in order to control the heat release and impurity levels from AB upon decomposition. The composite materials were prepared by mechanical ball milling, and their H2 release properties were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The formation of volatile products from decomposition side reactions, such as borazine (N3B3H6) was determined by mass spectrometry (MS). Sieverts type pressure-composition-temperature (PCT) gas-solid reaction instrument was adopted to observe the kinetics of the H2 release reactions of the combined systems and neat AB. In situ 11B MAS-NMR revealed a destabilized decomposition pathway. We found that by adding specific metal hydrides to AB we can eliminate the impurities and mitigate the heat release.

  14. Warming early Mars with H2 and CO2

    NASA Astrophysics Data System (ADS)

    Batalha, N.; Kasting, J. F.

    2014-03-01

    A recent study by R. Ramirez et al. (Nature Geosci., 2013) demonstrated that an atmosphere with 1.3-4 bar of CO2 and water, in addition to 5-20% H2, could raise the mean surface temperature of early Mars above the freezing point of water. This is thought to be necessary in order to produce enough rainfall (or snowfall) to carve the Martian valleys. Volcanic outgassing could in principle, have generated both CI2 and H2. Mars' mantle is highly reduced, however, and so carbon was probably outgassed as CO and CH4, rather than as CO2. Furthermore, much of the H2 in Mars' early atmosphere could have come from outgassed CH4 and H2S. We will use a 1-D photochemical model to see how efficiently CO, CH4, and H2S are converted to CO2 and H2. Previous work by K. Zahnle (JGR, 2008) suggests that CO, rather than CO2, might become the dominant carbon-containing gas in such an atmosphere. This possibility will also be investigated.

  15. Greywater treatment by UVC/H2O2.

    PubMed

    Chin, W H; Roddick, F A; Harris, J L

    2009-09-01

    Greywater treatment by UVC/H(2)O(2) was investigated with regard to the removal of chemical oxygen demand (COD). A COD reduction from 225 to 30 mgl(-1) (overall removal of 87%) was achieved after settling overnight and subsequent irradiation for 3h with 10mM H(2)O(2). Most of the contaminants were removed by oxidation since only 13% COD was removed by settlement. The removal of COD in the greywater followed a second-order kinetic equation, r=0.0637[COD][H(2)O(2)], up to 10mM H(2)O(2). A slightly enhanced COD removal was observed at the initial pH of 10 compared with pH 3 and 7. This was attributed to the dissociation of H(2)O(2) to O(2)H(-). The treatment was not affected by total concentration of carbonate (c(T)) of at least 3 mM, above which operation between pH 3 and 5 was essential. The initial biodegradability of the settled greywater (as BOD(5):COD) was 0.22. After 2h UVC/H(2)O(2) treatment, a higher proportion of the residual contaminants was biodegradable (BOD(5):COD=0.41) which indicated its potential as a pre-treatment for a biological process. PMID:19656542

  16. Greywater treatment by UVC/H2O2.

    PubMed

    Chin, W H; Roddick, F A; Harris, J L

    2009-09-01

    Greywater treatment by UVC/H(2)O(2) was investigated with regard to the removal of chemical oxygen demand (COD). A COD reduction from 225 to 30 mgl(-1) (overall removal of 87%) was achieved after settling overnight and subsequent irradiation for 3h with 10mM H(2)O(2). Most of the contaminants were removed by oxidation since only 13% COD was removed by settlement. The removal of COD in the greywater followed a second-order kinetic equation, r=0.0637[COD][H(2)O(2)], up to 10mM H(2)O(2). A slightly enhanced COD removal was observed at the initial pH of 10 compared with pH 3 and 7. This was attributed to the dissociation of H(2)O(2) to O(2)H(-). The treatment was not affected by total concentration of carbonate (c(T)) of at least 3 mM, above which operation between pH 3 and 5 was essential. The initial biodegradability of the settled greywater (as BOD(5):COD) was 0.22. After 2h UVC/H(2)O(2) treatment, a higher proportion of the residual contaminants was biodegradable (BOD(5):COD=0.41) which indicated its potential as a pre-treatment for a biological process.

  17. 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).

  18. Enhanced ethanol production from deacetylated yellow poplar acid hydrolysate by Pichia stipitis.

    PubMed

    Cho, Dae Haeng; Shin, Soo-Jeong; Bae, Yangwon; Park, Chulhwan; Kim, Yong Hwan

    2010-07-01

    In this study, alkaline-pretreatment for the extraction of acetic acid from xylan of hemicellulose was introduced prior to concentrated acid hydrolysis of yellow poplar wood meal. Ethanol fermentability in deacetylated yellow poplar hydrolysate (DYPH) by Pichia stipitis was also investigated. The alkali-pretreatment conditions were evaluated in terms of temperature, reaction time, and alkalinity. 94% of the acetyl group in xylan of the yellow poplar hemicellulose fraction was extracted using 0.5% sodium hydroxide solution at 60 degrees C for 60 min. The cell growth and ethanol production of P. stipitis was strongly affected by acetic acid, either in synthetic medium with 7.1g/l of acetic acid added or in yellow poplar hydrolysate (YPH) containing 7.1g/l of acetic acid. On the other hand, ethanol production in DYPH was slightly higher than that of the control although cell growth decreased by 34%. In the case of DYPH, the ethanol yield, volumetric ethanol productivity, and theoretical yield percentage was 0.48 g/g, 0.40 g/lh, and 93.2%, respectively. Thus, the alkaline-pretreatment method greatly enhanced the ethanol fermentability of yellow poplar hydrolysate. PMID:19959357

  19. Production of bio-fuel ethanol from distilled grain waste eluted from Chinese spirit making process.

    PubMed

    Tan, Li; Sun, Zhaoyong; Zhang, Wenxue; Tang, Yueqin; Morimura, Shigeru; Kida, Kenji

    2014-10-01

    Distilled grain waste eluted from Chinese spirit making is rich in carbohydrates, and could potentially serve as feedstock for the production of bio-fuel ethanol. Our study evaluated two types of saccharification methods that convert distilled grain waste to monosaccharides: enzymatic saccharification and concentrated H2SO4 saccharification. Results showed that enzymatic saccharification performed unsatisfactorily because of inefficient removal of lignin during pretreatment. Concentrated H2SO4 saccharification led to a total sugar recovery efficiency of 79.0 %, and to considerably higher sugar concentrations than enzymatic saccharification. The process of ethanol production from distilled grain waste based on concentrated H2SO4 saccharification was then studied. The process mainly consisted of concentrated H2SO4 saccharification, solid-liquid separation, decoloration, sugar-acid separation, oligosaccharide hydrolysis, and continuous ethanol fermentation. An improved simulated moving bed system was employed to separate sugars from acid after concentrated H2SO4 saccharification, by which 95.8 % of glucose and 85.8 % of xylose went into the sugar-rich fraction, while 83.3 % of H2SO4 went into the acid-rich fraction. A flocculating yeast strain, Saccharomyces cerevisiae KF-7, was used for continuous ethanol fermentation, which produced an ethanol yield of 91.9-98.9 %, based on glucose concentration.

  20. Melting of H2SO4·4H2O Particles upon Cooling: Implications for Polar Stratospheric Clouds

    PubMed

    Koop; Carslaw

    1996-06-14

    Polar stratospheric clouds (PSCs) are important for the chemical activation of chlorine compounds and subsequent ozone depletion. Solid PSCs can form on sulfuric acid tetrahydrate (SAT) (H2SO4·4H2O) nuclei, but recent laboratory experiments have shown that PSC nucleation on SAT is strongly hindered. A PSC formation mechanism is proposed in which SAT particles melt upon cooling in the presence of HNO3 to form liquid HNO3-H2SO4-H2O droplets 2 to 3 kelvin above the ice frost point. This mechanism offers a PSC formation temperature that is defined by the ambient conditions and sets a temperature limit below which PSCs should form.

  1. 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.

  2. Interaction between sulphide and H 2O in silicate melts

    NASA Astrophysics Data System (ADS)

    Stelling, Jan; Behrens, Harald; Wilke, Max; Göttlicher, Jörg; Chalmin-Aljanabi, Emilie

    2011-06-01

    Reaction between dissolved water and sulphide was experimentally investigated in soda-lime-silicate (NCS) and sodium trisilicate (NS3) melts at temperatures from 1000 to 1200 °C and pressures of 100 or 200 MPa in internally heated gas pressure vessels. Diffusion couple experiments were conducted at water-undersaturated conditions with one half of the couple being doped with sulphide (added as FeS or Na 2S; 1500-2000 ppm S by weight) and the other with H 2O (˜3.0 wt.%). Additionally, two experiments were performed using a dry NCS glass cylinder and a free H 2O fluid. Here, the melt was water-saturated at least at the melt/fluid interface. Profiling by electron microprobe (sulphur) and infrared microscopy (H 2O) demonstrate that H 2O diffusion in the melts is faster by 1.5-2.3 orders of magnitude than sulphur diffusion and, hence, H 2O can be considered as a rapidly diffusing oxidant while sulphur is quasi immobile in these experiments. In Raman spectra a band at 2576 cm -1 appears in the sulphide - H 2O transition zone which is attributed to fundamental S-H stretching vibrations. Formation of new IR absorption bands at 5025 cm -1 (on expense of the combination band of molecular H 2O at 5225 cm -1) and at 3400 cm -1 was observed at the front of the in-diffusing water in the sulphide bearing melt. The appearance and intensity of these two IR bands is correlated with systematic changes in S K-edge XANES spectra. A pre-edge excitation at 2466.5 eV grows with increasing H 2O concentration while the sulphide peak at 2474.0 eV decreases in intensity relative to the peak at 2477.0 eV and the feature at 2472.3 eV becomes more pronounced (all energies are relative to the sulphate excitation, calibrated to 2482.5 eV). The observations by Raman, IR and XANES spectroscopy indicate a well coordinated S 2- - H 2O complex which was probably formed in the glasses during cooling at the glass transition. No oxidation of sulphide was observed in any of the diffusion couple

  3. 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

  4. 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

  5. Hyperfine excitation of linear molecules by para- and ortho-H2: application to the HCl-H2 system.

    PubMed

    Lanza, Mathieu; Lique, François

    2014-10-28

    The determination of hyperfine structure resolved excitation cross sections and rate coefficients due to H2 collisions is required to interpret astronomical spectra. In this paper, we present several theoretical approaches to compute these data. An almost exact recoupling approach and approximate sudden methods are presented. We apply these different approaches to the HCl-H2 collisional system in order to evaluate their respective accuracy. HCl-H2 hyperfine structure resolved cross sections and rate coefficients are then computed using recoupling and approximate sudden methods. As expected, the approximate sudden approaches are more accurate when the collision energy increases and the results suggest that these approaches work better for para-H2 than for ortho-H2 colliding partner. For the first time, we present HCl-H2 hyperfine structure resolved rate coefficients, computed here for temperatures ranging from 5 to 300 K. The usual Δj1 = ΔF1 propensity rules are observed for the hyperfine transitions. The new rate coefficients will significantly help the interpretation of interstellar HCl emission lines observed with current and future telescopes. We expect that these new data will allow a better determination of the HCl abundance in the interstellar medium, that is crucial to understand the interstellar chlorine chemistry.

  6. 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.

  7. Evaluation of proposed natural corrosion inhibitors for X-52 carbon steel in ethanol media

    NASA Astrophysics Data System (ADS)

    Oliveira, Rafael F.

    This work describes the testing performed for corrosion control actions for X-52 carbon steel in ethanol media by using inhibitors, the following compounds were included: linalyl formate, linalyl acetate, linalyl butyrate, citronellyl acetate and 1-pentylallyl acetate. The experiments were performed in an electrochemical 3 electrode system with an X-52 steel rotating cylinder electrode (RCE) with rotational speed adjusted to 130 RPM. The system was deaerated by bubbling nitrogen gas into the ethanol solution. The Electrochemical Impedance Spectroscopy (EIS) technique was used to characterize the metal/electrolyte interface. Experimental testing was performed in anhydrous ethanol solution with 5 mM or 10 mM of one inhibitor. Surface analyses for the corroded surfaces were obtained by scanning electron microscopy (SEM) and White light interferometry (WLI). The results suggest that linalyl formate promotes the highest corrosion inhibition efficiency at 10 mM, followed by citronellyl acetate and linalyl butyrate. At this concentration, 1-pentylallyl acetate and linalyl acetate have not promoted corrosion inhibition. At a concentration of 5 mM, linalyl formate, linalyl acetate and linalyl butyrate promoted high inhibition efficiencies during the first hours but none was able to promote a longer protection than one day, possibly due to chemical degradation, chemical reactions and/or reduced surface coverage. The linalyl formate is considered the best chemical for inhibition purposes, especially at the concentration of 10 mM.

  8. 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.

  9. 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.

  10. JB-9322, a new selective histamine H2-receptor antagonist with potent gastric mucosal protective properties.

    PubMed

    Palacios, B; Montero, M J; Sevilla, M A; Román, L S

    1995-05-01

    1. JB-9322 is a selective histamine H2-receptor antagonist with gastric antisecretory activity and mucosal protective properties. 2. The affinity of JB-9322 for the guinea-pig atria histamine H2-receptor was approximately 2 times greater than that of ranitidine. 3. In vivo, the ID50 value for the inhibition of gastric acid secretion in pylorus-ligated rats was 5.28 mg kg-1 intraperitoneally. JB-9322 also dose-dependently inhibited gastric juice volume and pepsin secretion. In gastric lumen-perfused rats, intravenous injection of JB-9322 dose-dependently reduced histamine-, pentagastrin- and carbachol-stimulated gastric acid secretion. 4. JB-9322 showed antiulcer activity against aspirin and indomethacin-induced gastric lesions and was more potent than ranitidine. 5. JB-9322 effectively inhibited macroscopic gastric haemorrhagic lesions induced by ethanol. Intraperitoneal injection was effective in preventing the lesions as well as oral treatment. The oral ID50 value for these lesions was 1.33 mg kg-1. By contrast, ranitidine (50 mg kg-1) failed to reduce these lesions. In addition, the protective effect of JB-9322 was independent of prostaglandin synthesis. 6. These results indicate that JB-9322 is a new antiulcer drug that exerts a potent cytoprotective effect in addition to its gastric antisecretory activity.

  11. 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.

  12. Inhibitory effects of H2-receptor antagonists on cytochrome P450 in male ICR mice.

    PubMed

    Kim, D H; Kim, E J; Han, S S; Roh, J K; Jeong, T C; Park, J H

    1995-08-01

    1. The present study was undertaken to examine the effects of H2-receptor antagonists including newly developed mifentidine derivatives, IY-80843 and IY-80845, on cytochrome P450(P450) in vitro and in vivo. 2. Initially, 3-methylcholanthrene-, phenobarbital-, ethanol- and dexamethasone-induced liver microsomes were prepared from male ICR mice to study in vitro effects of above chemicals on ethoxyresorufin O-deethylase(EROD), pentoxyresorufin O-dealkylase(PROD), p-nitrophenol hydroxylase and erythromycin N-demethylase(ERDM) activities, respectively. It was found that histamine, cimetidine and famotidine were not inhibitory to four enzyme activities. Meanwhile, mifentidine slightly inhibited EROD and PROD activities and its derivatives IY-80843 and IY-80845 strongly inhibited PROD, EROD and ERDM activities. 3. Prolongation of hexobarbital-induced sleeping time was determined in male ICR mice to confirm in vitro inhibitory effects of mifentidine and its derivatives in vivo. It was observed that cimetidine, mifentidine, IY-80843 and IY-80845 caused dose-dependent increases in the sleeping time, indicating the inhibition of P450 responsible for hexobarbital metabolism. 4. It was concluded that mifentidine and its derivatives are P450 inhibitors and that our newly synthesized IY-80843 is most inhibitory. 5. The present results indicate that mifentidine and its derivatives not only antagonise the H2-receptor but also inhibit P450 enzymes. PMID:7576828

  13. JB-9322, a new selective histamine H2-receptor antagonist with potent gastric mucosal protective properties.

    PubMed Central

    Palacios, B.; Montero, M. J.; Sevilla, M. A.; Román, L. S.

    1995-01-01

    1. JB-9322 is a selective histamine H2-receptor antagonist with gastric antisecretory activity and mucosal protective properties. 2. The affinity of JB-9322 for the guinea-pig atria histamine H2-receptor was approximately 2 times greater than that of ranitidine. 3. In vivo, the ID50 value for the inhibition of gastric acid secretion in pylorus-ligated rats was 5.28 mg kg-1 intraperitoneally. JB-9322 also dose-dependently inhibited gastric juice volume and pepsin secretion. In gastric lumen-perfused rats, intravenous injection of JB-9322 dose-dependently reduced histamine-, pentagastrin- and carbachol-stimulated gastric acid secretion. 4. JB-9322 showed antiulcer activity against aspirin and indomethacin-induced gastric lesions and was more potent than ranitidine. 5. JB-9322 effectively inhibited macroscopic gastric haemorrhagic lesions induced by ethanol. Intraperitoneal injection was effective in preventing the lesions as well as oral treatment. The oral ID50 value for these lesions was 1.33 mg kg-1. By contrast, ranitidine (50 mg kg-1) failed to reduce these lesions. In addition, the protective effect of JB-9322 was independent of prostaglandin synthesis. 6. These results indicate that JB-9322 is a new antiulcer drug that exerts a potent cytoprotective effect in addition to its gastric antisecretory activity. PMID:7647984

  14. Rotationally Excited H2 in the Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Xue, Rui; Welty, Daniel; Wong, Tony

    2013-03-01

    We have performed a survey study of rotational excited-state H2 Lyman-Werner absorption lines in the entire FUSE Magellanic Clouds Legacy archive. These lines reflect the UV pumping and formation conditions of H2, enabling a more comprehensive study of H2 gas properties, e.g. J-level populations N(J) and b-values (generally indicating the velocity dispersion). Combining with our previous measurements of N(Hi) and N(H2), we derived H2 excitation temperatures, gas volume density n(H), and local UV radiation field strength I UV for each sight line. The results indicate a weaker correlation between n(H) and I UV in Magellanic Clouds than the Galactic sight lines. We also obtained N(H)/E(B - V) ratios from the Spitzer-SAGE and previous CO J = 1 - 0 / Hi 21 cm surveys at sight line locations, using dust modeling and standard line brightness-column density conversion factors. They show a roughly linear correlation with absorption-based N(H)/E(B - V) values, and have a similar scatter (˜0.7 dex) across the LMC and SMC.

  15. H2 double ionization with few-cycle laser pulses

    NASA Astrophysics Data System (ADS)

    Saugout, S.; Charron, E.; Cornaggia, C.

    2008-02-01

    The temporal dynamics of double ionization of H2 has been investigated both experimentally and theoretically with few-cycle laser pulses. The main observables are the proton spectra associated with the H++H+ fragmentation channel. The model is based on the time-dependent Schrödinger equation and treats the electronic and nuclear coordinates on the same level. Therefore it allows the ultrafast nuclear dynamics to be followed as a function of the laser pulse duration, carrier-envelope phase offset, and peak intensity. We mainly report results in the sequential double-ionization regime above 2×1014Wcm-2 . The proton spectra are shifted to higher energies as the pulse duration is reduced from 40 down to 10 fs. The good agreement between the model predictions and the experimental data at 10 fs permits a theoretical study with pulse durations down to a few femtoseconds. We demonstrate the very fast nuclear dynamics of the H2+ ion for a pulse duration as short as 1 fs between the two ionization events, giving H2+ from H2 and H++H+ from H2+ . The carrier-envelope phase offset plays a significant role only for pulse durations shorter than 4 fs. At 10 fs, the laser intensity dependence of the proton spectra is fairly well reproduced by the model.

  16. 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

  17. 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.

  18. 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.

  19. 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. PMID:19486862

  20. 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

  1. Characterization of the H2- and CO-dependent chemolithotrophic potentials of the acetogens Clostridium thermoaceticum and Acetogenium kivui.

    PubMed

    Daniel, S L; Hsu, T; Dean, S I; Drake, H L

    1990-08-01

    Strains of Clostridium thermoaceticum were tested for H2- and CO-dependent growth in a defined medium containing metals, minerals, vitamins, cysteine-sulfide, CO2-bicarbonate, and H2 or CO. Ten of the thirteen strains tested grew at the expense of H2 and CO, and C. thermoaceticum ATCC 39073 was chosen for further study. The doubling times for H2- and CO-dependent growth under chemolithotrophic conditions (the defined medium with nicotinic acid as sole essential vitamin and sulfide as sole reducer) were 25 and 10 h, respectively. Product stiochiometries for chemolithotrophic cultures approximated: 4.1H2 + 2.4CO2----CH3COOH + 0.1 cell C + 0.3 unrecovered C and 6.8CO----CH3COOH + 3.5CO2 + 0.4 cell C + 0.9 unrecovered C. H2-dependent growth produced significantly higher acetate concentrations per unit of biomass synthesized than did CO- or glucose-dependent growth. In contrast, the doubling time for H2-dependent growth under chemolithotrophic conditions (the defined medium without vitamins and sulfide as sole reducer) by Acetogenium kivui ATCC 33488 was 2.7 h; as a sole energy source, CO was not growth supportive for A. kivui. The YH2 values for A. kivui and C. thermoaceticum were 0.91 and 0.46 g of cell dry weight per mol of H2 consumed, respectively; the YCO value for C. thermoaceticum was 1.28 g of cell dry weight per mol of CO consumed. The specific activities of hydrogenase and CO dehydrogenase in both acetogens were influenced by the energy source utilized for growth and were significantly lower in C. thermoaceticum than in A. kivui. With extracts of H2-cultivated cells and benzyl viologen as electron acceptor, the Vmax values for hydrogenase from C. thermoaceticum and A. kivui were 155.7 and 1,670 micromoles of H2 oxidized per min mg of protein, respectively; the Vmax values for CO dehydrogenase from C. thermoaceticum and A. kivui were 90.6 and 2,973 micromoles of CO oxidized per min per mg of protein, respectively.

  2. Enhanced expression of aconitase raises acetic acid resistance in Acetobacter aceti.

    PubMed

    Nakano, Shigeru; Fukaya, Masahiro; Horinouchi, Sueharu

    2004-06-15

    Acetobacter spp. are used for industrial vinegar production because of their high ability to oxidize ethanol to acetic acid and high resistance to acetic acid. Two-dimensional gel electrophoretic analysis of a soluble fraction of Acetobacter aceti revealed the presence of several proteins whose production was enhanced, to various extents, in response to acetic acid in the medium. A protein with an apparent molecular mass of 100 kDa was significantly enhanced in amount by acetic acid and identified to be aconitase by NH2-terminal amino acid sequencing and subsequent gene cloning. Amplification of the aconitase gene by use of a multicopy plasmid in A. aceti enhanced the enzymatic activity and acetic acid resistance. These results showed that aconitase is concerned with acetic acid resistance. Enhancement of the aconitase activity turned out to be practically useful for acetic acid fermentation, because the A. aceti transformant harboring multiple copies of the aconitase gene produced a higher concentration of acetic acid with a reduced growth lag-time.

  3. 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.

  4. 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.

  5. Biological reformation of ethanol to hydrogen by Rhodopseudomonas palustris CGA009.

    PubMed

    Liu, Yuan; Ghosh, Dipankar; Hallenbeck, Patrick C

    2015-01-01

    A future hydrogen economy requires the sustainable production of renewable hydrogen. One method to produce hydrogen from stored renewable energy could be through reformation of bioethanol. However, chemically catalyzed reformation processes, although well studied, still present a number of significant technical challenges. Here, bioreformation of ethanol to hydrogen by photofermentation with the photosynthetic bacterium Rhodopseudomonas palustris is described. Cultures were shown to tolerate up to 2% ethanol. An RSM (response surface methodology) was carried out in which three key factors, light intensity, and ethanol and glutamate concentrations were varied. The results showed that nearly 2mol of H2 could be obtained from one mole of ethanol, 33% of that theoretically possible.

  6. 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.

  7. Dynamics of H2 dissociation on the close-packed (111) surface of the noblest metal: H2 + Au(111)

    NASA Astrophysics Data System (ADS)

    Wijzenbroek, Mark; Helstone, Darcey; Meyer, Jörg; Kroes, Geert-Jan

    2016-10-01

    We have performed calculations on the dissociative chemisorption of H2 on un-reconstructed and reconstructed Au(111) with density functional theory, and dynamics calculations on this process on un-reconstructed Au(111). Due to a very late barrier for dissociation, H2 + Au(111) is a candidate H2-metal system for which the dissociative chemisorption could be considerably affected by the energy transfer to electron-hole pairs. Minimum barrier geometries and potential energy surfaces were computed for six density functionals. The functionals tested yield minimum barrier heights in the range of 1.15-1.6 eV, and barriers that are even later than found for the similar H2 + Cu(111) system. The potential energy surfaces have been used in quasi-classical trajectory calculations of the initial (v,J) state resolved reaction probability for several vibrational states v and rotational states J of H2 and D2. Our calculations may serve as predictions for state-resolved associative desorption experiments, from which initial state-resolved dissociative chemisorption probabilities can be extracted by invoking detailed balance. The vibrational efficacy ηv=0→1 reported for D2 dissociating on un-reconstructed Au(111) (about 0.9) is similar to that found in earlier quantum dynamics calculations on H2 + Ag(111), but larger than found for D2 + Cu(111). With the two functionals tested most extensively, the reactivity of H2 and D2 exhibits an almost monotonic increase with increasing rotational quantum number J. Test calculations suggest that, for chemical accuracy (1 kcal/mol), the herringbone reconstruction of Au(111) should be modeled.

  8. Hydrogen peroxide formation and actin filament reorganization by Cdc42 are essential for ethanol-induced in vitro angiogenesis.

    PubMed

    Qian, Yong; Luo, Jia; Leonard, Stephen S; Harris, Gabriel K; Millecchia, Lyndell; Flynn, Daniel C; Shi, Xianglin

    2003-05-01

    This report focuses on the identification of the molecular mechanisms of ethanol-induced in vitro angiogenesis. The manipulation of angiogenesis is an important therapeutic approach for the treatment of cancer, cardiovascular diseases, and chronic inflammation. Our results showed that ethanol stimulation altered the integrity of actin filaments and increased the formation of lamellipodia and filopodia in SVEC4-10 cells. Further experiments demonstrated that ethanol stimulation increased cell migration and invasion and induced in vitro angiogenesis in SVEC4-10 cells. Mechanistically, ethanol stimulation activated Cdc42 and produced H(2)O(2) a reactive oxygen species intermediate in SVEC4-10 cells. Measuring the time course of Cdc42 activation and H(2)O(2) production upon ethanol stimulation revealed that the Cdc42 activation and the increase of H(2)O(2) lasted more than 3 h, which indicates the mechanisms of the long duration effects of ethanol on the cells. Furthermore, either overexpression of a constitutive dominant negative Cdc42 or inhibition of H(2)O(2) production abrogated the effects of ethanol on SVEC4-10 cells, indicating that both the activation of Cdc42 and the production of H(2)O(2) are essential for the actions of ethanol. Interestingly, we also found that overexpression of a constitutive dominant positive Cdc42 itself was sufficient to produce H(2)O(2) and to induce in vitro angiogenesis. Taken together, our results suggest that ethanol stimulation can induce H(2)O(2) production through the activation of Cdc42, which results in reorganizing actin filaments and increasing cell motility and in vitro angiogenesis. PMID:12598535

  9. 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.

  10. H2O2 Release from Human Granulocytes during Phagocytosis

    PubMed Central

    Root, Richard K.; Metcalf, Julia A.

    1977-01-01

    Normal and cytochalasin B-treated human granulocytes have been studied to determine some of the interrelationships between phagocytosis-induced respiration and superoxide and hydrogen peroxide formation and release into the extracellular medium by intact cells. By using the scopoletin fluorescent assay to continuously monitor extracellular hydrogen peroxide concentrations during contact of cells with opsonized staphylococci, it was demonstrated that the superoxide scavengers ferricytochrome c and nitroblue tetrazolium significantly reduced the amount of H2O2 released with time from normal cells but did not abolish it. This inhibitory effect was reversed by the simultaneous addition of superoxide dismutase (SOD), whereas the addition of SOD alone increased the amount of detectable H2O2 in the medium. The addition of sodium azide markedly inhibited myeloperoxidase-H2O2-dependent protein iodination and more than doubled H2O2 release, including the residual amount remaining after exposure of the cells to ferricytochrome c, suggesting its origin from an intracellular pool shared by several pathways for H2O2 catabolism. When cells were pretreated with cytochalasin B and opsonized bacteria added, reduced oxygen consumption was observed, but this was in parallel to a reduction in specific binding of organisms to the cells when compared to normal. Under the influence of inhibited phagosome formation by cytochalasin B, the cells released an increased amount of superoxide and peroxide into the extracellular medium relative to oxygen consumption, and all detectable peroxide release could be inhibited by the addition of ferricytochrome c. Decreased H2O2 production in the presence of this compound could not be ascribed to diminished bacterial binding, decreased oxidase activity, or increased H2O2 catabolism and was reversed by the simultaneous addition of SOD. Furthermore, SOD and ferricytochrome c had similar effects on another H2O2-dependent reaction, protein iodination, in

  11. Permeance of H2 through porous graphene from molecular dynamics

    NASA Astrophysics Data System (ADS)

    Liu, Hongjun; Dai, Sheng; Jiang, De-en

    2013-12-01

    A recent experiment (Koenig et al., 2012 [15]) demonstrated the capability of porous graphene as one-atom-thin membrane to separate gases by molecular sieving. A quantitative connection between the measured leak rate and the simulated gas permeance has yet to be established. Using H2 as a model gas, here we determine its permeance through porous graphene from molecular dynamics (MD) simulations. Trajectories are used to directly obtain H2 flux, pressure drop across the graphene membrane, and subsequently, H2 permeance. The permeance is determined to be on the order of 105 GPU (gas permeance unit) for pressure driving forces ranging from 2 to 163 atm. By relating to the experimental leak rate, we then use the permeation data to estimate the pore density in the experimentally created porous graphene.

  12. Uranus' (3-0) H2 quadrupole line profiles

    NASA Astrophysics Data System (ADS)

    Trafton, L.

    1987-04-01

    Spectra of Uranus' S3(0) and S3(1) H2 quadrupole lines, obtained during the 1978-1980 apparitions, are analyzed, and are found to require the presence of a deep cloud. Modifications of the Baines and Bergstralh (1986) standard model, including an additional haze layer above the 16-km-am H2 level which contains strongly absorbing particles, are needed to fit the observations. For a Rayleigh phase function, such a haze (uniformly mixed with the gas above this level) would have an absorption optical depth of 0.16 and a single scattering particle albedo of 0.30. This modification would imply a fraction of normal H2 equal to 0.25 + or - 0.10, in agreement with the Baines and Bergstralh standard model.

  13. Jovian H2 dayglow emission (1978-1989)

    NASA Astrophysics Data System (ADS)

    McGrath, M. A.; Ballester, G. E.; Moos, H. W.

    1990-07-01

    The IUE data set accumulated through 10 years of Jovian equatorial observations is used to measure the long-term temporal variation of the H2 dayglow emission. The model that best fits the data indicates a possible correlation between long-term solar activity and the Jovian H2 emission in the region 1500-1700 A between 1978 and 1989, which spans the decline in solar activity for solar cycle 21 and the rise in solar activity accompanying solar cycle 22. The magnitude of the observed variation is closer to that of the solar Ly-alpha flux than the 10.7 cm radio flux. Short-wavelength H2 band emission intensity is inconsistent with the amount of long-wavelength emission but may be reconciled if relatively low-energy excitation or fluorescence of solar radiation is invoked. No persistent longitudinal feature analogous to the H I Ly-alpha can be identified.

  14. Substrate Recognition of Histone H2B by DUBm

    NASA Astrophysics Data System (ADS)

    Henderson, Elizabeth; Berndsen, Christopher; Wolberger, Cynthia

    2011-03-01

    The SAGA complex is a transcriptional coactivator that regulates gene expression in eukaryotes via histone acetylation and deubiquitination, which are crucial for transcription. Our lab is investigating the SAGA-dependent deubiquitination of histone H2B. The deubiquitinating module (DUBm) of SAGA is comprised of a ubiquitin-specific protease, Ubp8, and three other proteins. It is known that Ubp8 cleaves ubiquitin from histone H2B, however, the specific way in which the enzyme binds to the substrate remains elusive. In order to unravel this mechanism, we attempted to determine the crystal structure of the substrate binding complex. We obtained this substrate by exploiting the techniques of intein chemistry to artificially ubiquitinate a histone H2B peptide, which we then co-crystallized with DUBm. Additionally, we synthesized Ub-K63R-linked chains and Ub-K48-linked chains and co-crystallized them with DUBm.

  15. 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.

  16. 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.

  17. H-2Dd exploits a four residue peptide binding motif

    PubMed Central

    1993-01-01

    We have characterized the amino acid sequences of over 20 endogenous peptides bound by a soluble analog of H-2Dd, H-2Dds. Synthetic analogs corresponding to self, viral, tumor, or motif peptides were then tested for their ability to bind to H-2Dd by serologic epitope induction assays using both purified soluble protein and cell surface H-2Dd. The dominant primary sequence motif included glycine at position 2, proline at position 3, and a hydrophobic COOH terminus: leucine, isoleucine, or phenylalanine at position 9 or 10. Ancillary support for high affinity binding was contributed by a positively charged residue at position 5. Three-dimensional computer models of H-2Dds/peptide complexes, based on the crystallographic structure of the human HLA-B27/peptide complex, showed that the basic residue at position 5 was in position to form a salt bridge with aspartic acid at position 156, a polymorphic residue of the H-2Dd heavy (H) chain. Analysis of 28 such models, including 17 based on nonamer self-peptides, revealed considerable variation in the structure of the major histocompatibility complex (MHC) surrounding peptide residue 1, depending on the size and charge of the side chain. Interactions between the side chains of peptide residues 5 and 7, and 6 and 8 commonly occurred. Those peptide positions with limited sequence variability and least solvent accessibility may satisfy structural requirements for high affinity binding of the peptide to the MHC class I H chain, whereas the highly variable positions of the peptide (such as positions 4, 6, and 8) may contribute more to the T cell epitopes. PMID:8245770

  18. Thermodynamics of the formation of sulfuric acid dimers in the binary (H2SO4-H2O) and ternary (H2SO4-H2O-NH3) system

    NASA Astrophysics Data System (ADS)

    Kürten, A.; Münch, S.; Rondo, L.; Bianchi, F.; Duplissy, J.; Jokinen, T.; Junninen, H.; Sarnela, N.; Schobesberger, S.; Simon, M.; Sipilä, M.; Almeida, J.; Amorim, A.; Dommen, J.; Donahue, N. M.