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Liu, Fengbao, Jinsheng Sun, Xianbin Huang y Yuan Geng. "Development of a Low-Molecular-Weight Filtrate Reducer with High-Temperature Resistance for Drilling Fluid Gel System". Gels 9, n.º 10 (7 de octubre de 2023): 805. http://dx.doi.org/10.3390/gels9100805.
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Currently, conventional polymeric filtrate reducers with high-temperature resistance for use in drilling fluids have high molecular weights, which greatly affects the rheological properties. Therefore, to address the challenges in regulating the rheology and filtration performance of high-density drilling fluids at high temperatures, it is essential to develop low-molecular-weight filtrate reducers with high-temperature resistance. In this study, a low-molecular-weight filtrate reducer with high-temperature resistance (LMF) was prepared via free radical polymerization from acrylamide and 2-acrylamido-2-methyl-1-propanesulfonic acid as monomers, tertiary dodecyl mercaptan as a chain transfer agent, and ammonium persulfate as the initiator. LMF was then characterized by infrared spectroscopy, thermogravimetric analysis, and gel permeation chromatography. The obtained filtrate reducer exhibits a weight-average molecular weight (Mw) of 3819 and an initial thermal decomposition temperature of 300.7 °C, indicating good thermal stability. The effects of LMF dosage, temperature, and NaCl dosage on the rheology and filtration performance of mud samples were also investigated, and the mechanism of action was revealed by zeta potential, particle size distribution, scanning electron microscopy, and adsorption measurements. The results reveal that LMF increases the mud sample viscosity and reduces its filtration. For example, the filtration of the mud sample with 2 wt% LMF was 7.2 mL, a reduction of 70% compared to that of a blank mud sample. Further, after aging at 210 °C for 16 h, the filtration of the same sample was 11.6 mL, and that of a mud sample with 2 wt% LMF and 35 wt% NaCl after aging at 180 °C for 16 h was 22 mL. Overall, we have reported a scheme to prepare a low-molecular-weight filtrate reducer with high-temperature resistance and superior filtrate-reducing effects, laying the foundation for the investigation and development of low-molecular-weight filtrate reducers.
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Wang, Qin, Chong Zhi Li, Jun Chao Liu y Mo Yi Xu. "Study and Application of a Modified Agent GHPC-1 for Green High-Performance Concrete". Advanced Materials Research 535-537 (junio de 2012): 1955–60. http://dx.doi.org/10.4028/www.scientific.net/amr.535-537.1955.
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A modified agent GHPC-1 for green high-performance concrete was composed of the strength-increasing groups of organic alcohol amine, the slump-retaining groups of carboxylate polymer and the workability-stabilizing groups of amide. It could be used through substituting some of polycarboxylate water-reducers or combining with polycarboxylate water-reducers to modify the workability of fresh concrete and to increase the strength of hardened concrete. The adaptability tests of cementing materials with admixtures show that the dispersing ability was almost not influenced but the retaining ability of paste flowing was evidently enhanced if the substitution of polycarboxylate water-reducers have been to 20 %. The comparative tests of concrete indicated that as 20 % content of GHPC-1 was added in polycarboxylate water-reducers, it could modify the concrete workability. If adding 0.6 % with polycarboxylate water-reducers it could save water by 5 % and cement 10 % and simultaneously modify the workability and to enhance the strength, or to reduce water by 2.5 % and increase the strength of 28 d by 5~8 MPa.
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Sun, Wei, Bojun Li, Weiping Zhu, Yuan Li, Qian Wang, Erdong Yao y Fujian Zhou. "Research on adsorption and damage characteristics of slick water in coalbed methane development". IOP Conference Series: Earth and Environmental Science 984, n.º 1 (1 de febrero de 2022): 012001. http://dx.doi.org/10.1088/1755-1315/984/1/012001.
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Abstract In the process of coalbed fracturing, the drag reducers absorbed on the surface of the coalbed causes water lock damage and decreases gas production efficiency of coalbed methane. Thus, research on low-damage coalbed drag reducers is of great significance. Aiming at four drag reducers with different molecular weights, the law of drag reducers adsorption was investigated through static adsorption test and contact angle tests. Afterwards, a core displacement experiment was carried out to study the damage rate of slick water to the coabed, and the nanoemulsion CND was used for competitive adsorption to relieve the influence of fracturing fluid adsorption on the core damage. Finally, through the static adsorption test results, combined with core SEM images before and after displacement, the internal relationship between adsorption and damage was revealed, and the optimal principles and control methods for reducing the damage of drag reducers to the coalbed were proposed. The results show that: the drag reducers with larger molecular weight are more likely to adsorb in the coalbed, which caused more severe damage to the coalbed reservoir. In contrast, drag reducers with lower molecular weight show a lower damage rate (less than 20%) to the reservoir, which is suitable for the preparation of low-damage slick water. Mechanistic studies have shown that the drag reducers is adsorbed on the surface of the organic matter in the coalbed, leading to the exposure of the hydrophilic end. Therefore, the hydrophilic area on the surface of the coal powder was enlarged, which forms the water film adhesion in the pore throat, causing the water lock to block the gas and liquid seepage channel, resulting in reduced permeability; Nanoemulsion and coal powder are more closely adsorbed, which can reduce the adsorption of drag reducers through competition with the adsorption matrix, reduce water lock damage, facilitating the subsequent drainage and gas collection process.
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Ch�neby, D., A. Brauman, B. Rabary y L. Philippot. "Differential Responses of Nitrate Reducer Community Size, Structure, and Activity to Tillage Systems". Applied and Environmental Microbiology 75, n.º 10 (20 de marzo de 2009): 3180–86. http://dx.doi.org/10.1128/aem.02338-08.
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ABSTRACT The main objective of this study was to determine how the size, structure, and activity of the nitrate reducer community were affected by adoption of a conservative tillage system as an alternative to conventional tillage. The experimental field, established in Madagascar in 1991, consists of plots subjected to conventional tillage or direct-seeding mulch-based cropping systems (DM), both amended with three different fertilization regimes. Comparisons of size, structure, and activity of the nitrate reducer community in samples collected from the top layer in 2005 and 2006 revealed that all characteristics of this functional community were affected by the tillage system, with increased nitrate reduction activity and numbers of nitrate reducers under DM. Nitrate reduction activity was also stimulated by combined organic and mineral fertilization but not by organic fertilization alone. In contrast, both negative and positive effects of combined organic and mineral fertilization on the size of the nitrate reducer community were observed. The size of the nitrate reducer community was a significant predictor of the nitrate reduction rates except in one treatment, which highlighted the inherent complexities in understanding the relationships the between size, diversity, and structure of functional microbial communities along environmental gradients.
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Zhang, Fan, Qun Zhang, Zhaohui Zhou, Lingling Sun y Yawen Zhou. "Study on the Effect of Different Viscosity Reducers on Viscosity Reduction and Emulsification with Daqing Crude Oil". Molecules 28, n.º 3 (1 de febrero de 2023): 1399. http://dx.doi.org/10.3390/molecules28031399.
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The urgent problem to be solved in heavy oil exploitation is to reduce viscosity and improve fluidity. Emulsification and viscosity reduction technology has been paid more and more attention and its developments applied. This paper studied the viscosity reduction performance of three types of viscosity reducers and obtained good results. The viscosity reduction rate, interfacial tension, and emulsification performance of three types of viscosity reducers including anionic sulfonate, non-ionic (polyether and amine oxide), and amphoteric betaine were compared with Daqing crude oil. The results showed that the viscosity reduction rate of petroleum sulfonate and betaine was 75–85%. The viscosity reduction rate increased as viscosity reducer concentration increased. An increase in the oil–water ratio and polymer decreased viscosity reduction. When the concentration of erucamide oxide was 0.2%, the ultra-low interfacial tension was 4.41 × 10−3 mN/m. When the oil–water ratio was 1:1, the maximum water separation rates of five viscosity reducers were different. With an increase in the oil–water ratio, the emulsion changed from o/w emulsion to w/o emulsion, and the stability was better. Erucamide oxide and erucic betaine had good viscosity reduction and emulsification effects on Daqing crude oil. This work can enrich knowledge of the viscosity reduction of heavy oil systems with low relative viscosity and enrich the application of viscosity reducer varieties.
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Choi, Euiso y Jay M. Rim. "Competition and Inhibition of Sulfate Reducers and Methane Producers in Anaerobic Treatment". Water Science and Technology 23, n.º 7-9 (1 de abril de 1991): 1259–64. http://dx.doi.org/10.2166/wst.1991.0577.
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Competition for substrate between sulfate reducing and methane producing bacteria, and the inhibitory effects of sulfide produced from microbial sulfate reduction were investigated in this study for the selection of a proper anaerobic treatment process using laboratory anaerobic contact units. Substrates used were both synthetic waste with various COD/SO42− ratios, and industrial wastes. Sulfate reducers and methane producers were very competitive at COD/SO42− ratio of 1.7 to 2.7. As the ratio increased/methane producers predominated, and sulfate reducers were predominating as the ratio decreased. Inhibitory concentrations were 2000 mg/l sulfate (160 to 200 mg/l sulfide) for sulfate reducers and 1200 mg/l sulfate (120 to 140 mg/l sulfide) for methane producers with synthetic substrate. But sulfide inhibitory concentrations were varied with hydraulic or organic loading rates and substrate used. As loading rates increased/the inhibitory effect was greater. A sulfide concentration of 240mg/l did not inhibit methane producers for sea-food waste treatment.
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Tang, Zhichuan, Zhengsong Qiu, Hanyi Zhong, Hui Mao, Kai Shan y Yujie Kang. "Novel Acrylamide/2-Acrylamide-2-3 Methylpropanesulfonic Acid/Styrene/Maleic Anhydride Polymer-Based CaCO3 Nanoparticles to Improve the Filtration of Water-Based Drilling Fluids at High Temperature". Gels 8, n.º 5 (20 de mayo de 2022): 322. http://dx.doi.org/10.3390/gels8050322.
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Filtration loss control under high-temperature conditions is a worldwide issue among water-based drilling fluids (WBDFs). A core–shell high-temperature filter reducer (PAASM-CaCO3) that combines organic macromolecules with inorganic nanomaterials was developed by combining acrylamide (AM), 2-acrylamide-2-methylpropane sulfonic acid (AMPS), styrene (St), and maleic anhydride (MA) as monomers and nano-calcium carbonate (NCC). The molecular structure of PAASM-CaCO3 was characterized. The average molecular weight of the organic part was 6.98 × 105 and the thermal decomposition temperature was about 300 °C. PAASM-CaCO3 had a better high-temperature resistance. The rheological properties and filtration performance of drilling fluids treated with PAASM-CaCO3 were stable before and after aging at 200 °C/16 h, and the effect of filtration control was better than that of commonly used filter reducers. PAASM-CaCO3 improved colloidal stability and mud cake quality at high temperatures.
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Wei, Juanming, Wenfeng Jia, Luo Zuo, Hao Chen y Yujun Feng. "Turbulent Drag Reduction with an Ultra-High-Molecular-Weight Water-Soluble Polymer in Slick-Water Hydrofracking". Molecules 27, n.º 2 (6 de enero de 2022): 351. http://dx.doi.org/10.3390/molecules27020351.
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Water-soluble polymers as drag reducers have been widely utilized in slick-water for fracturing shale oil and gas reservoirs. However, the low viscosity characteristics, high operating costs, and freshwater consumption of conventional friction reducers limit their practical use in deeper oil and gas reservoirs. Therefore, a high viscosity water-soluble friction reducer (HVFR), poly-(acrylamide-co-acrylic acid-co-2-acrylamido-2-methylpropanesulphonic acid), was synthesized via free radical polymerization in aqueous solution. The molecular weight, solubility, rheological behavior, and drag reduction performance of HVFR were thoroughly investigated. The results showed that the viscosity-average molecular weight of HVFR is 23.2 × 106 g⋅mol−1. The HVFR powder could be quickly dissolved in water within 240 s under 700 rpm. The storage modulus (G′) and loss modulus (G″) as well as viscosity of the solutions increased with an increase in polymer concentration. At a concentration of 1700 mg⋅L−1, HVFR solution shows 67% viscosity retention rate after heating from 30 to 90 °C, and the viscosity retention rate of HVFR solution when increasing CNaCl to 21,000 mg⋅L−1 is 66%. HVFR exhibits significant drag reduction performance for both low viscosity and high viscosity. A maximum drag reduction of 80.2% is attained from HVFR at 400 mg⋅L−1 with 5.0 mPa⋅s, and drag reduction of HVFR is 75.1% at 1700 mg⋅L−1 with 30.2 mPa⋅s. These findings not only indicate the prospective use of HVFR in slick-water hydrofracking, but also shed light on the design of novel friction reducers utilized in the oil and gas industry.
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Baloza, Marwa, Susann Henkel, Sabine Kasten, Moritz Holtappels y Massimiliano Molari. "The Impact of Sea Ice Cover on Microbial Communities in Antarctic Shelf Sediments". Microorganisms 11, n.º 6 (14 de junio de 2023): 1572. http://dx.doi.org/10.3390/microorganisms11061572.
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The area around the Antarctic Peninsula (AP) is facing rapid climatic and environmental changes, with so far unknown impacts on the benthic microbial communities of the continental shelves. In this study, we investigated the impact of contrasting sea ice cover on microbial community compositions in surface sediments from five stations along the eastern shelf of the AP using 16S ribosomal RNA (rRNA) gene sequencing. Redox conditions in sediments with long ice-free periods are characterized by a prevailing ferruginous zone, whereas a comparatively broad upper oxic zone is present at the heavily ice-covered station. Low ice cover stations were highly dominated by microbial communities of Desulfobacterota (mostly Sva1033, Desulfobacteria, and Desulfobulbia), Myxococcota, and Sva0485, whereas Gammaproteobacteria, Alphaproteobacteria, Bacteroidota, and NB1-j prevail at the heavy ice cover station. In the ferruginous zone, Sva1033 was the dominant member of Desulfuromonadales for all stations and, along with eleven other taxa, showed significant positive correlations with dissolved Fe concentrations, suggesting a significant role in iron reduction or an ecological relationship with iron reducers. Our results indicate that sea ice cover and its effect on organic carbon fluxes are the major drivers for changes in benthic microbial communities, favoring potential iron reducers at stations with increased organic matter fluxes.
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Li, Ting, Yan Ping Yin, Li Ning Gao y Hua Xin Chen. "Research on the Improving of Warm Mix Asphalt Technology by Adding Organic Viscosity-Reducers". Advanced Materials Research 1079-1080 (diciembre de 2014): 118–23. http://dx.doi.org/10.4028/www.scientific.net/amr.1079-1080.118.
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Inconsideration of the application defects of organic viscosity-reducing warm mixasphalt (represented by Sasobit), such as poor adhesion with aggregate,inadequate of low-temperature deformation, four methods for Sasobit modificationwere proposed and they were blending with polymer, grafting, hydroisomerizationand adjusting molecular weightdistribution width,then the feasibility of each method was analyzed. Moreover, given that performance evaluation of warm mix asphaltmixture still referenced for that of hot mix asphalt mixture, adhesion (water stability) evaluation method based on surface free energy and low temperature performanceevaluation method based on glass transition temperature were put forward to optimize the performance evaluation system of warm mix asphaltmixture.
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Dasgupta, Shamik, Xiaotong Peng y Kaiwen Ta. "Interaction between Microbes, Minerals, and Fluids in Deep-Sea Hydrothermal Systems". Minerals 11, n.º 12 (26 de noviembre de 2021): 1324. http://dx.doi.org/10.3390/min11121324.
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The discovery of deep-sea hydrothermal vents in the late 1970s widened the limits of life and habitability. The mixing of oxidizing seawater and reduction of hydrothermal fluids create a chemical disequilibrium that is exploited by chemosynthetic bacteria and archaea to harness energy by converting inorganic carbon into organic biomass. Due to the rich variety of chemical sources and steep physico-chemical gradients, a large array of microorganisms thrive in these extreme environments, which includes but are not restricted to chemolithoautotrophs, heterotrophs, and mixotrophs. Past research has revealed the underlying relationship of these microbial communities with the subsurface geology and hydrothermal geochemistry. Endolithic microbial communities at the ocean floor catalyze a number of redox reactions through various metabolic activities. Hydrothermal chimneys harbor Fe-reducers, sulfur-reducers, sulfide and H2-oxidizers, methanogens, and heterotrophs that continuously interact with the basaltic, carbonate, or ultramafic basement rocks for energy-yielding reactions. Here, we briefly review the global deep-sea hydrothermal systems, microbial diversity, and microbe–mineral interactions therein to obtain in-depth knowledge of the biogeochemistry in such a unique and geologically critical subseafloor environment.
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Urbańska, Weronika. "Recovery of Co, Li, and Ni from Spent Li-Ion Batteries by the Inorganic and/or Organic Reducer Assisted Leaching Method". Minerals 10, n.º 6 (20 de junio de 2020): 555. http://dx.doi.org/10.3390/min10060555.
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The battery powder (anodic and cathodic mass) manually separated from spent Li-ion batteries used in laptops was subjected to acidic reductive leaching to recover the Co, Li, and Ni contained in it. In the laboratory experiments, 1.5 M sulfuric acid was used as the leaching agent and the reducing agents were 30% H2O2 solution or/and glutaric acid. Glutaric acid is a potential new reducing agent in the leaching process of spent lithium-ion batteries (LIBs). The influence of the type of the used reducer on obtained recovery degrees of Co, Li, and Ni as well as the synergism of the two tested reducing compounds were analyzed. As a result, it was determined that it is possible to efficiently hydrometallurgically separate Co, Li, and Ni from battery powder into solutions. The highest recovery degrees of the investigated metals (Co: 87.85%; Li: 99.91%; Ni: 91.46%) were obtained for samples where two reducers, perhydrol and glutaric acid, were added, thus confirming the assumed synergic action of H2O2 and C5H8O4 in a given reaction environment.
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Skidmore, Mark L., Julia M. Foght y Martin J. Sharp. "Microbial Life beneath a High Arctic Glacier". Applied and Environmental Microbiology 66, n.º 8 (1 de agosto de 2000): 3214–20. http://dx.doi.org/10.1128/aem.66.8.3214-3220.2000.
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ABSTRACT The debris-rich basal ice layers of a high Arctic glacier were shown to contain metabolically diverse microbes that could be cultured oligotrophically at low temperatures (0.3 to 4°C). These organisms included aerobic chemoheterotrophs and anaerobic nitrate reducers, sulfate reducers, and methanogens. Colonies purified from subglacial samples at 4°C appeared to be predominantly psychrophilic. Aerobic chemoheterotrophs were metabolically active in unfrozen basal sediments when they were cultured at 0.3°C in the dark (to simulate nearly in situ conditions), producing 14CO2from radiolabeled sodium acetate with minimal organic amendment (≥38 μM C). In contrast, no activity was observed when samples were cultured at subfreezing temperatures (≤−1.8°C) for 66 days. Electron microscopy of thawed basal ice samples revealed various cell morphologies, including dividing cells. This suggests that the subglacial environment beneath a polythermal glacier provides a viable habitat for life and that microbes may be widespread where the basal ice is temperate and water is present at the base of the glacier and where organic carbon from glacially overridden soils is present. Our observations raise the possibility that in situ microbial production of CO2 and CH4beneath ice masses (e.g., the Northern Hemisphere ice sheets) is an important factor in carbon cycling during glacial periods. Moreover, this terrestrial environment may provide a model for viable habitats for life on Mars, since similar conditions may exist or may have existed in the basal sediments beneath the Martian north polar ice cap.
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Li, Ming-Jun, Meng-Yun Wei, Xiao-Ting Fan y Guo-Wei Zhou. "Underestimation about the Contribution of Nitrate Reducers to Iron Cycling Indicated by Enterobacter Strain". Molecules 27, n.º 17 (30 de agosto de 2022): 5581. http://dx.doi.org/10.3390/molecules27175581.
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Nitrate-reducing iron(II) oxidation (NRFO) has been intensively reported in various bacteria. Iron(II) oxidation is found to be involved in both enzymatic and chemical reactions in nitrate-reducing Fe(II)-oxidizing microorganisms (NRFOMs). However, little is known about the relative contribution of biotic and abiotic reactions to iron(II) oxidation for the common nitrate reducers during the NRFO process. In this study, the typical nitrate reducers, four Enterobacter strains E. hormaechei, E. tabaci, E. mori and E. asburiae, were utilized as the model microorganisms. The comparison of the kinetics of nitrate, iron(II) and nitrite and N2O production in setups with and without iron(II) indicates a mixture of enzymatic and abiotic oxidation of iron(II) in all four Enterobacter strains. It was estimated that 22−29% of total oxidized iron(II) was coupled to microbial nitrate reduction by E. hormaechei, E. tabaci, E. mori, and E. asburiae. Enterobacter strains displayed an metabolic inactivity with heavy iron(III) encrustation on the cell surface in the NRFOmedium during days of incubation. Moreover, both respiratory and periplasmic nitrate-reducing genes are encoded by genomes of Enterobacter strains, suggesting that cell encrustation may occur with periplasmic iron(III) oxide precipitation as well as the surface iron(II) mineral coating for nitrate reducers. Overall, this study clarified the potential role of nitrate reducers in the biochemical cycling of iron under anoxic conditions, in turn, re-shaping their activity during denitrification because of cell encrustation with iron(III) minerals.
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Ahmad Yunus Nasution. "DEVELOPMENT OF KNIFE EYES ON THE MAKING PROCESS OF ORGANIC BURNING PROCESS OF 7 LITERS FOR UMKM". ABDIMAS TALENTA: Jurnal Pengabdian Kepada Masyarakat 3, n.º 2 (2 de octubre de 2019): 110–17. http://dx.doi.org/10.32734/abdimastalenta.v3i2.2637.
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The planning and design of the blades mixer for the organic slurry dough mixer is the application of the sciences obtained in real college. The main purpose of making blades mixer for this slurry dough mixer is to get an effective, efficient blades mixer design and higher quality organic slurry. With the making of this blades mixer, it is expected to contribute positively in the middle industry engaged in the food industry. The author designed several forms of modeling of blades mixer capable of stirring the organic pulp mixture with a capacity of 7 liters. The blades mixer are planned to use 304 steinless steel Austenitic material. For a planned blades mixer rotation of 35 rpm, and to achieve such a large rotation, pulleys and gearboxes (reducers) take an important role to achieve the planned rotation. The treatment carried out for this organic slurry dough mixer can be in the form of planned and unplanned treatments. With this report, it is expected to be able to add knowledge in the field of engineering.
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Stams, A. J. M., C. M. Plugge, F. A. M. de Bok, B. H. G. W. van Houten, P. Lens, H. Dijkman y J. Weijma. "Metabolic interactions in methanogenic and sulfate-reducing bioreactors". Water Science and Technology 52, n.º 1-2 (1 de julio de 2005): 13–20. http://dx.doi.org/10.2166/wst.2005.0493.
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In environments where the amount of electron acceptors is insufficient for complete breakdown of organic matter, methane is formed as the major reduced end product. In such methanogenic environments organic acids are degraded by syntrophic consortia of acetogenic bacteria and methanogenic archaea. Hydrogen consumption by methanogens is essential for acetogenic bacteria to convert organic acids to acetate and hydrogen. Several syntrophic cocultures growing on propionate and butyrate have been described. These syntrophic fatty acid-degrading consortia are affected by the presence of sulfate. When sulfate is present sulfate-reducing bacteria compete with methanogenic archaea for hydrogen and acetate, and with acetogenic bacteria for propionate and butyrate. Sulfate-reducing bacteria easily outcompete methanogens for hydrogen, but the presence of acetate as carbon source may influence the outcome of the competition. By contrast, acetoclastic methanogens can compete reasonably well with acetate-degrading sulfate reducers. Sulfate-reducing bacteria grow much faster on propionate and butyrate than syntrophic consortia.
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Rao, S. S., M. D. Dickman y H. G. Thode. "Isotopic and Diatom Evidence of Bacterial Sulphate Reduction in Sediments". Water Quality Research Journal 24, n.º 2 (1 de mayo de 1989): 215–32. http://dx.doi.org/10.2166/wqrj.1989.013.
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Abstract Sulphur contents and sulphur isotope ratios (δ34 So/00 values) in deep sediments (10–12 cms; circa 50–100 years before the present) and surface sediments (0–2 cm; circa 0–10 years before the present) from eight lakes located north of Lake Superior, Canada indicated that surface sediments had a significantly higher sulphur content (largely organic sulphur) per gram dry weight and a lower sulphur isotope ratio than the deeper layers. The increased sulphur content and decreased sulphur isotope ratios (δ34 S0/00 values) in the surficial sediments were much greater for the lakes near and downwind from the Wawa sintering plant than for more remote lakes reflecting the impact of the sintering plant emissions on the lake environment. A significant relationship was observed between the sulphate reducing bacterial populations and the magnitude of the isotope shift in the study lakes. It was evident from the data that the greater the abundance of sulphate reducers the greater was the surface sediment sulphate content and the degree of isotope fractionation in the anaerobic and organic rich sediments. The surface sediments of the eight study lakes revealed isotopic evidence of bacterial sulphate reduction. The deeper sediments, however, did not reveal such a condition due to the absence of sulphate reducers. The rate of lake acidification as inferred from the downcore diatom inferred pH profile for each of the study lakes was not significantly correlated with the amount of sulphur in the lake sediments, nor was it correlated with the density of sulphate reducing bacteria or shifts in the sulphur isotope ratios (δ34S).
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Polprasert, Chongchin y Charles N. Haas. "Effect of sulfate on anaerobic processes fed with dual substrates". Water Science and Technology 31, n.º 9 (1 de mayo de 1995): 101–7. http://dx.doi.org/10.2166/wst.1995.0349.
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Anaerobic reactors were operated in a semi-batch mode and fed with the dual substrates glucose (G) plus acetic acid (Ac) as primary organic sources to study the effect of sulfate on COD oxidation. With glucose, COD removal by methane formation was seriously inhibited, resulting in COD accumulation in the reactor. Although acetic acid can be consumed by some sulfate-reducing species, it was not a major substrate for sulfate reduction, but was largely responsible for methane formation in the anaerobic mixed culture used in this study. With dual substrates, extreme inhibition of methanogenesis did not occur as did with glucose alone. Instead, methanogens were found to work in harmony with acid formers as well as sulfate reducers to oxidise COD. Interestingly, from 12-hour monitoring, increased G/Ac COD ratios decreased COD removal rates as well as biogas production, but resulted in higher sulfate reduction. This suggests that there should be an optimal feed G/Ac COD ratio, for which removal of both organics could be maximised.
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Kumar, Brajesh. "Green Synthesis of Gold, Silver, and Iron Nanoparticles for the Degradation of Organic Pollutants in Wastewater". Journal of Composites Science 5, n.º 8 (16 de agosto de 2021): 219. http://dx.doi.org/10.3390/jcs5080219.
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The green synthesis of nanoscale materials is of special interest to researchers all over the world. We describe a simple, robust, inexpensive, and environmentally friendly approach to the synthesis of gold, silver, and iron nanoparticles using a variety of biomolecules/phytochemicals as potential reducers and stabilizers. The green approach to the controlled synthesis of nanoparticles with different morphologies is based on the use of plant extracts. Green synthesized nanoparticles can be used as catalysts, photocatalysts, adsorbents, or alternative agents for the elimination of various organic dyes. The kinetic enhancement of nanoparticles for the degradation/removal of dyes could provide significant and valuable insights for the application of biochemically functionalized nanoparticles in engineering. In this review, current plant-mediated strategies for preparing nanoparticles of gold, silver, and iron are briefly described, and morphologically dependent nanoparticles for the degradation of organic pollutants in wastewater are highlighted. Overall, the approach presented in the article supports environmental protection and is a promising alternative to other synthesis techniques.
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Baptista, J. D. C., T. Donnelly, D. Rayne y R. J. Davenport. "Microbial mechanisms of carbon removal in subsurface flow wetlands". Water Science and Technology 48, n.º 5 (1 de septiembre de 2003): 127–34. http://dx.doi.org/10.2166/wst.2003.0298.
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The microbial mechanisms of carbon removal in subsurface flow wetlands were studied, in one wetland with plants and one without plants. Particular emphasis was given to the influence of plants in the treatment process. Wetlands without plants showed higher carbon removal than those with plants, 63% and 51%, respectively (p<0.05). Molecular analysis of the bacterial diversity, growth rates and specific microbial activities showed that the two wetlands were different, especially towards the outlet of the two systems. Sulphate reducers and methanogens were found in both wetlands, and they are thought to be the main removers of soluble organic carbon in these two systems.
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Bradley, J. A., S. Arndt, J. P. Amend, E. Burwicz, A. W. Dale, M. Egger y D. E. LaRowe. "Widespread energy limitation to life in global subseafloor sediments". Science Advances 6, n.º 32 (agosto de 2020): eaba0697. http://dx.doi.org/10.1126/sciadv.aba0697.
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Microbial cells buried in subseafloor sediments comprise a substantial portion of Earth’s biosphere and control global biogeochemical cycles; however, the rate at which they use energy (i.e., power) is virtually unknown. Here, we quantify organic matter degradation and calculate the power utilization of microbial cells throughout Earth’s Quaternary-age subseafloor sediments. Aerobic respiration, sulfate reduction, and methanogenesis mediate 6.9, 64.5, and 28.6% of global subseafloor organic matter degradation, respectively. The total power utilization of the subseafloor sediment biosphere is 37.3 gigawatts, less than 0.1% of the power produced in the marine photic zone. Aerobic heterotrophs use the largest share of global power (54.5%) with a median power utilization of 2.23 × 10−18 watts per cell, while sulfate reducers and methanogens use 1.08 × 10−19 and 1.50 × 10−20 watts per cell, respectively. Most subseafloor cells subsist at energy fluxes lower than have previously been shown to support life, calling into question the power limit to life.
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Willian, Nancy, Hilfi Pardi y Dina Fitriyah. "Colorimetric Detection of Mercury Using Silver Nanoparticles: A Review". BIO Web of Conferences 70 (2023): 01008. http://dx.doi.org/10.1051/bioconf/20237001008.
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Manufacturing nanometals that use natural materials as bioreductant media is still a significant concern due to their environmentally friendly properties. The use of silver nanoparticles prepared using plants or organic materials. They are used for the rapid detection of sustainable mercury ions. The use of these natural materials is capable of producing stable nanoparticles and environmentally friendly nanoparticle synthesis. In this paper, we will report the synthesis of silver nanoparticles with various types of reducers and stabilizers, mechanisms, and nanoparticle characterization for applications of colorimetric sensors of mercury ions in water pollutants. The aim is for the reader to obtain comprehensive information about the ability of the silver nanoparticle as a colorimeter sensor.
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Stevenson, Mark A., Johan C. Faust, Luiza L. Andrade, Felipe S. Freitas, Neil D. Gray, Karen Tait, Katharine R. Hendry et al. "Transformation of organic matter in a Barents Sea sediment profile: coupled geochemical and microbiological processes". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, n.º 2181 (31 de agosto de 2020): 20200223. http://dx.doi.org/10.1098/rsta.2020.0223.
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Process-based, mechanistic investigations of organic matter transformation and diagenesis directly beneath the sediment–water interface (SWI) in Arctic continental shelves are vital as these regions are at greatest risk of future change. This is in part due to disruptions in benthic–pelagic coupling associated with ocean current change and sea ice retreat. Here, we focus on a high-resolution, multi-disciplinary set of measurements that illustrate how microbial processes involved in the degradation of organic matter are directly coupled with inorganic and organic geochemical sediment properties (measured and modelled) as well as the extent/depth of bioturbation. We find direct links between aerobic processes, reactive organic carbon and highest abundances of bacteria and archaea in the uppermost layer (0–4.5 cm depth) followed by dominance of microbes involved in nitrate/nitrite and iron/manganese reduction across the oxic-anoxic redox boundary (approx. 4.5–10.5 cm depth). Sulfate reducers dominate in the deeper (approx. 10.5–33 cm) anoxic sediments which is consistent with the modelled reactive transport framework. Importantly, organic matter reactivity as tracked by organic geochemical parameters ( n -alkanes, n -alkanoic acids, n -alkanols and sterols) changes most dramatically at and directly below the SWI together with sedimentology and biological activity but remained relatively unchanged across deeper changes in sedimentology. This article is part of the theme issue ‘The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning’.
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Brostow, Witold, Hamide Ertepinar y R. P. Singh. "Flow of dilute polymer solutions: chain conformations and degradation of drag reducers". Macromolecules 23, n.º 24 (noviembre de 1990): 5109–18. http://dx.doi.org/10.1021/ma00226a013.
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Achmadi, Anggi Pratiwi Sella y Sarwoko Mangkoedihardjo. "Organic Wastewater-Grey Water Management In The Residential Area". Asian Journal of Engineering, Social and Health 3, n.º 2 (10 de febrero de 2024): 285–90. http://dx.doi.org/10.46799/ajesh.v3i2.238.
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Grey Water wastewater in residential areas near Gisik Cemandi river has a COD value range of 146 – 516 Mg / L and the BOD value is in the range of 76 – 280 Mg / L. While Gisik Cemandi River is included in Class III rivers with COD values of 22 – 31 Mg / L. For the water quality of the Gisik Cemandi river to be maintained and not go down, the residential area must have structured Grey Water wastewater management. The management needed is technical, institutional, and financial management. Technical management planning is carried out by providing recommendations so that residential area has management activities in the form of maintenance and repair by adjusting the available facilities and infrastructure. In addition, a Wastewater Treatment Plant is needed that is used for biological treatment because the BOD/COD ratio of Residential Grey Water is 0.528 or biodegradable. Biological processing of gray water can utilize plants as BOD and COD reducers. In carrying out technical management, it is necessary to have institutional management as a monitoring role between implementers and citizens. The recommendation of institutional management is to be able to follow the institutional practical guidance of the Ministry of Public Works. All technical and institutional management activities require financial management as capital in every implementation of Grey Water organic wastewater management in residential areas. Financial management calculations must be adjusted to regional regulations and calculated for the next few years by considering the value of inflation.
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Dhillon, Ashita, Andreas Teske, Jesse Dillon, David A. Stahl y Mitchell L. Sogin. "Molecular Characterization of Sulfate-Reducing Bacteria in the Guaymas Basin". Applied and Environmental Microbiology 69, n.º 5 (mayo de 2003): 2765–72. http://dx.doi.org/10.1128/aem.69.5.2765-2772.2003.
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ABSTRACT The Guaymas Basin (Gulf of California) is a hydrothermal vent site where thermal alteration of deposited planktonic and terrestrial organic matter forms petroliferous material which supports diverse sulfate-reducing bacteria. We explored the phylogenetic and functional diversity of the sulfate-reducing bacteria by characterizing PCR-amplified dissimilatory sulfite reductase (dsrAB) and 16S rRNA genes from the upper 4 cm of the Guaymas sediment. The dsrAB sequences revealed that there was a major clade closely related to the acetate-oxidizing delta-proteobacterial genus Desulfobacter and a clade of novel, deeply branching dsr sequences related to environmental dsr sequences from marine sediments in Aarhus Bay and Kysing Fjord (Denmark). Other dsr clones were affiliated with gram-positive thermophilic sulfate reducers (genus Desulfotomaculum) and the delta-proteobacterial species Desulforhabdus amnigena and Thermodesulforhabdus norvegica. Phylogenetic analysis of 16S rRNAs from the same environmental samples resulted in identification of four clones affiliated with Desulfobacterium niacini, a member of the acetate-oxidizing, nutritionally versatile genus Desulfobacterium, and one clone related to Desulfobacula toluolica and Desulfotignum balticum. Other bacterial 16S rRNA bacterial phylotypes were represented by non-sulfate reducers and uncultured lineages with unknown physiology, like OP9, OP8, as well as a group with no clear affiliation. In summary, analyses of both 16S rRNA and dsrAB clone libraries resulted in identification of members of the Desulfobacteriales in the Guaymas sediments. In addition, the dsrAB sequencing approach revealed a novel group of sulfate-reducing prokaryotes that could not be identified by 16S rRNA sequencing.
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Balalaiev, Oleksandr. "The role of microbiota in paleoecosystems for forming the molecular profile of coals". E3S Web of Conferences 168 (2020): 00041. http://dx.doi.org/10.1051/e3sconf/202016800041.
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Mass deposits of fossil coals can be formed in certain evolution periods of the Earth’s biosphere, and they are the result of biogeocenosis functioning. A unique combination of ecological factors leads to the emergence of specific biomes with short trophic chains, an imbalance in the carbon cycle and desynchronization in the flows of substance and energy. The molecular structure of coal is a complex conglomerate of various stable organic compounds of primary and secondary metabolites of biogeocenosis reducers. The molecular profile includes numerous classes of lowand high-molecular organic substances that interact closely with each other. Multiple classes are not endless, the interaction is not chaotic, and their number and relationships are determined by paleoecologic patterns and coalification. Even a small fragment of the profile includes valuable information about the genesis of individual compounds and the biogeochemical situation when forming the coal bed. Microbiota impact does not end with a period of mortmass accumulation, which is never fully mineralized. In the coalification process, favorable environmental conditions may arise for the rebirth of the microorganisms’ lives in coal beds.
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Delattre, Hadrien, Jing Chen, Matthew J. Wade y Orkun S. Soyer. "Thermodynamic modelling of synthetic communities predicts minimum free energy requirements for sulfate reduction and methanogenesis". Journal of The Royal Society Interface 17, n.º 166 (mayo de 2020): 20200053. http://dx.doi.org/10.1098/rsif.2020.0053.
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Microbial communities are complex dynamical systems harbouring many species interacting together to implement higher-level functions. Among these higher-level functions, conversion of organic matter into simpler building blocks by microbial communities underpins biogeochemical cycles and animal and plant nutrition, and is exploited in biotechnology. A prerequisite to predicting the dynamics and stability of community-mediated metabolic conversions is the development and calibration of appropriate mathematical models. Here, we present a generic, extendable thermodynamic model for community dynamics and calibrate a key parameter of this thermodynamic model, the minimum energy requirement associated with growth-supporting metabolic pathways, using experimental population dynamics data from synthetic communities composed of a sulfate reducer and two methanogens. Our findings show that accounting for thermodynamics is necessary in capturing the experimental population dynamics of these synthetic communities that feature relevant species using low energy growth pathways. Furthermore, they provide the first estimates for minimum energy requirements of methanogenesis (in the range of −30 kJ mol −1 ) and elaborate on previous estimates of lactate fermentation by sulfate reducers (in the range of −30 to −17 kJ mol −1 depending on the culture conditions). The open-source nature of the developed model and demonstration of its use for estimating a key thermodynamic parameter should facilitate further thermodynamic modelling of microbial communities.
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Deng, Milin, Yong Zheng, Zi-Yang He, Maokui Lyu, Shengsheng Jin, Hao Yang, Hanshuo Zhang, Ji-Zheng He y Yongxin Lin. "Organic carbon negatively affects the diversity of soil nitrous oxide reducers in Chinese fir plantations at a regional scale". Applied Soil Ecology 200 (agosto de 2024): 105457. http://dx.doi.org/10.1016/j.apsoil.2024.105457.
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Li, Jian, Jinsheng Sun, Kaihe Lv, Yuxi Ji, Jintao Ji y Jingping Liu. "Nano-Modified Polymer Gels as Temperature- and Salt-Resistant Fluid-Loss Additive for Water-Based Drilling Fluids". Gels 8, n.º 9 (29 de agosto de 2022): 547. http://dx.doi.org/10.3390/gels8090547.
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With the continuous exploration and development of oil and gas resources to deep formations, the key treatment agents of water-based drilling fluids face severe challenges from high temperatures and salinity, and the development of high temperature and salt resistance filtration reducers has always been the focus of research in the field of oilfield chemistry. In this study, a nano-silica-modified co-polymer (NS-ANAD) gel was synthesized by using acrylamide, isopropylacrylamide, 2-acrylamide-2-methyl propane sulfonic acid, diallyl dimethyl ammonium chloride, and double-bond-modified inorganic silica particles (KH570-SiO2) through free radical co-polymerization. The introduction of nanotechnology enhances the polymer’s resistance to high temperature degradation, making it useful as a high-temperature-resistant fluid loss reducer. Moreover, the anions (sulfonates) and cations (quaternary ammonium) enhance the extension of the polymer and the adsorption on the surface of bentonite particles in a saline environment, which in turn improves the salt resistance of the polymer. The drilling fluids containing 2.0 wt% NS-ANAD co-polymer gels still show excellent rheological and filtration performance, even after aging in high temperature (200 °C) and high salinity (saturated salt) environments, showing great potential for application in deep and ultra-deep drilling engineering.
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Long, Wenjun, Xialei Zhu, Fengshan Zhou, Zhen Yan, Amutenya Evelina, Jinliang Liu, Zhongjin Wei y Liang Ma. "Preparation and Hydrogelling Performances of a New Drilling Fluid Filtrate Reducer from Plant Press Slag". Gels 8, n.º 4 (23 de marzo de 2022): 201. http://dx.doi.org/10.3390/gels8040201.
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Plant press slag (PPS) containing abundant cellulose and starch is a byproduct in the deep processing of fruits, cereals, and tuberous crops products. PPS can be modified by using caustic soda and chloroacetic acid to obtain an inexpensive and environmentally friendly filtrate reducer of drilling fluids. The optimum mass ratio of mNaOH:mMCA:mPPS is 1:1:2, the optimum etherification temperature is 75 °C, and the obtained product is a natural mixture of carboxymethyl cellulose and carboxymethyl starch (CMCS). PPS and CMCS are characterized by using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric, X-ray photoelectron spectroscopy, and elemental analysis. The filtration loss performance of CMCS is stable before and after hot-rolling aging at 120 °C in 4.00% NaCl and saturated NaCl brine base slurry. The minimum filtration loss value of CMCS is 5.28 mL/30 min at the dosage of 1.50%. Compared with the commercial filtrate reducers with a single component, i.e., carboxymethyl starch (CMS) and low viscosity sodium carboxymethyl cellulose (LV-CMC), CMCS have a better tolerance to high temperature of 120 °C and high concentration of NaCl. The filtration loss performance of low-cost CMCS can reach the standards of LV-CMC and CMS of the specification of water-based drilling fluid materials in petroleum industry.
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Mahadevan, R., D. R. Bond, J. E. Butler, A. Esteve-Nuñez, M. V. Coppi, B. O. Palsson, C. H. Schilling y D. R. Lovley. "Characterization of Metabolism in the Fe(III)-Reducing Organism Geobacter sulfurreducens by Constraint-Based Modeling". Applied and Environmental Microbiology 72, n.º 2 (febrero de 2006): 1558–68. http://dx.doi.org/10.1128/aem.72.2.1558-1568.2006.
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ABSTRACT Geobacter sulfurreducens is a well-studied representative of the Geobacteraceae, which play a critical role in organic matter oxidation coupled to Fe(III) reduction, bioremediation of groundwater contaminated with organics or metals, and electricity production from waste organic matter. In order to investigate G. sulfurreducens central metabolism and electron transport, a metabolic model which integrated genome-based predictions with available genetic and physiological data was developed via the constraint-based modeling approach. Evaluation of the rates of proton production and consumption in the extracellular and cytoplasmic compartments revealed that energy conservation with extracellular electron acceptors, such as Fe(III), was limited relative to that associated with intracellular acceptors. This limitation was attributed to lack of cytoplasmic proton consumption during reduction of extracellular electron acceptors. Model-based analysis of the metabolic cost of producing an extracellular electron shuttle to promote electron transfer to insoluble Fe(III) oxides demonstrated why Geobacter species, which do not produce shuttles, have an energetic advantage over shuttle-producing Fe(III) reducers in subsurface environments. In silico analysis also revealed that the metabolic network of G. sulfurreducens could synthesize amino acids more efficiently than that of Escherichia coli due to the presence of a pyruvate-ferredoxin oxidoreductase, which catalyzes synthesis of pyruvate from acetate and carbon dioxide in a single step. In silico phenotypic analysis of deletion mutants demonstrated the capability of the model to explore the flexibility of G. sulfurreducens central metabolism and correctly predict mutant phenotypes. These results demonstrate that iterative modeling coupled with experimentation can accelerate the understanding of the physiology of poorly studied but environmentally relevant organisms and may help optimize their practical applications.
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Chèneby, D., D. Bru, N. Pascault, P. A. Maron, L. Ranjard y L. Philippot. "Role of Plant Residues in Determining Temporal Patterns of the Activity, Size, and Structure of Nitrate Reducer Communities in Soil". Applied and Environmental Microbiology 76, n.º 21 (10 de septiembre de 2010): 7136–43. http://dx.doi.org/10.1128/aem.01497-10.
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ABSTRACT The incorporation of plant residues into soil not only represents an opportunity to limit soil organic matter depletion resulting from cultivation but also provides a valuable source of nutrients such as nitrogen. However, the consequences of plant residue addition on soil microbial communities involved in biochemical cycles other than the carbon cycle are poorly understood. In this study, we investigated the responses of one N-cycling microbial community, the nitrate reducers, to wheat, rape, and alfalfa residues for 11 months after incorporation into soil in a field experiment. A 20- to 27-fold increase in potential nitrate reduction activity was observed for residue-amended plots compared to the nonamended plots during the first week. This stimulating effect of residues on the activity of the nitrate-reducing community rapidly decreased but remained significant over 11 months. During this period, our results suggest that the potential nitrate reduction activity was regulated by both carbon availability and temperature. The presence of residues also had a significant effect on the abundance of nitrate reducers estimated by quantitative PCR of the narG and napA genes, encoding the membrane-bound and periplasmic nitrate reductases, respectively. In contrast, the incorporation of the plant residues into soil had little impact on the structure of the narG and napA nitrate-reducing community determined by PCR-restriction fragment length polymorphism (RFLP) fingerprinting. Overall, our results revealed that the addition of plant residues can lead to important long-term changes in the activity and size of a microbial community involved in N cycling but with limited effects of the type of plant residue itself.
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York, Jamie L., Robert H. Magnuson, Dino Camdzic y Kevin A. Schug. "Characterization of ethoxylated alcohols in friction reducers using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry". Rapid Communications in Mass Spectrometry 33, n.º 15 (2 de julio de 2019): 1286–92. http://dx.doi.org/10.1002/rcm.8468.
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Boyd, Eric S., Rachel K. Lange, Andrew C. Mitchell, Jeff R. Havig, Trinity L. Hamilton, Melissa J. Lafrenière, Everett L. Shock, John W. Peters y Mark Skidmore. "Diversity, Abundance, and Potential Activity of Nitrifying and Nitrate-Reducing Microbial Assemblages in a Subglacial Ecosystem". Applied and Environmental Microbiology 77, n.º 14 (27 de mayo de 2011): 4778–87. http://dx.doi.org/10.1128/aem.00376-11.
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ABSTRACTSubglacial sediments sampled from beneath Robertson Glacier (RG), Alberta, Canada, were shown to harbor diverse assemblages of potential nitrifiers, nitrate reducers, and diazotrophs, as assessed byamoA,narG, andnifHgene biomarker diversity. Although archaealamoAgenes were detected, they were less abundant and less diverse than bacterialamoA, suggesting that bacteria are the predominant nitrifiers in RG sediments. Maximum nitrification and nitrate reduction rates in microcosms incubated at 4°C were 280 and 18.5 nmol of N per g of dry weight sediment per day, respectively, indicating the potential for these processes to occurin situ. Geochemical analyses of subglacial sediment pore waters and bulk subglacial meltwaters revealed low concentrations of inorganic and organic nitrogen compounds. These data, when coupled with a C/N atomic ratio of dissolved organic matter in subglacial pore waters of ∼210, indicate that the sediment communities are N limited. This may reflect the combined biological activities of organic N mineralization, nitrification, and nitrate reduction. Despite evidence of N limitation and the detection ofnifH, we were unable to detect biological nitrogen fixation activity in subglacial sediments. Collectively, the results presented here suggest a role for nitrification and nitrate reduction in sustaining microbial life in subglacial environments. Considering that ice currently covers 11% of the terrestrial landmass and has covered significantly greater portions of Earth at times in the past, the demonstration of nitrification and nitrate reduction in subglacial environments furthers our understanding of the potential for these environments to contribute to global biogeochemical cycles on glacial-interglacial timescales.
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Reinhardt, Manuel, Walter Goetz, Jan-Peter Duda, Christine Heim, Joachim Reitner y Volker Thiel. "Organic signatures in Pleistocene cherts from Lake Magadi (Kenya) – implications for early Earth hydrothermal deposits". Biogeosciences 16, n.º 12 (19 de junio de 2019): 2443–65. http://dx.doi.org/10.5194/bg-16-2443-2019.
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Abstract. Organic matter in Archean hydrothermal cherts may provide an important archive for molecular traces of the earliest life on Earth. The geobiological interpretation of this archive, however, requires a sound understanding of organic matter preservation and alteration in hydrothermal systems. Here we report on organic matter (including molecular biosignatures) enclosed in hydrothermally influenced cherts of the Pleistocene Lake Magadi (Kenya; High Magadi Beds and Green Beds). The Magadi cherts contain low organic carbon (< 0.4 wt %) that occurs in the form of finely dispersed clots, layers, or encapsulated within microscopic carbonate rhombs. Both extractable (bitumen) and non-extractable organic matter (kerogen) were analyzed. The bitumens contain immature “biolipids” like glycerol mono- and diethers (e.g., archaeol and extended archaeol), fatty acids, and alcohols indicative for, inter alia, thermophilic cyanobacteria, sulfate reducers, and haloarchaea. However, co-occurring “geolipids” such as n-alkanes, hopanes, and polycyclic aromatic hydrocarbons (PAHs) indicate that a fraction of the bitumen has been thermally altered to early or peak oil window maturity. This more mature fraction likely originated from defunctionalization of dissolved organic matter and/or hydrothermal petroleum formation at places of higher thermal flux. Like the bitumens, the kerogens also show variations in thermal maturities, which can partly be explained by admixture of thermally pre-altered macromolecules. However, findings of archaea-derived isoprenoid moieties (C20 and C25 chains) in kerogen pyrolysates indicate rapid sequestration of some archaeal lipids into kerogen while hydrothermal alteration was active. We posit that such early sequestration may enhance the resistance of molecular biosignatures against in situ hydrothermal and post-depositional alteration. Furthermore, the co-occurrence of organic matter with different thermal maturities in the Lake Magadi cherts suggests that similar findings in Archean hydrothermal deposits could partly reflect original environmental conditions and not exclusively post-depositional overprint or contamination. Our results support the view that kerogen in Archean hydrothermal cherts may contain important information on early life. Our study also highlights the suitability of Lake Magadi as an analog system for hydrothermal chert environments on the Archean Earth.
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Presley, Rachel y Jane M. Caffrey. "Nitrogen Fixation in Subtropical Seagrass Sediments: Seasonal Patterns in Activity in Santa Rosa Sound, Florida, USA". Journal of Marine Science and Engineering 9, n.º 7 (14 de julio de 2021): 766. http://dx.doi.org/10.3390/jmse9070766.
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Seagrass beds are important coastal habitats that are diminishing globally. Nitrogen, a key nutrient, often limits seagrass growth. Nitrogen fixation provides new, bioavailable nitrogen to the plants. This study explores its importance and factors controlling rates in sediments colonized by two dominant taxa in Northwest Florida, Thalassia testudinum and Halodule wrightii, compared to unvegetated sediments. We hypothesized that nitrogen fixation rates would be greater in seagrass colonized sediments, particularly during high growth periods. We expected to observe a positive relationship between rates and porewater sulfide concentrations because sulfate reducers were the dominant diazotrophs in similar studies. Rates were higher in vegetated areas. In H. wrightii beds, nitrogen fixation was driven by the decreased availability of porewater ammonium relative to phosphorus. In T. testudinum beds, rates were highest during winter. Organic matter may be a controlling factor in all substrate types albeit the exact mechanism driving nitrogen fixation differs slightly. During the summer and fall, nitrogen fixation provided between 1–15% of T. testudinum nitrogen demand. Annually, nitrogen fixation provided 4% and 1% of T. testudinum and H. wrightii nitrogen demand, respectively. Nitrogen fixation was an important source of nitrogen during periods of senescence and dormancy when organic matter content was high.
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Zhang, Xiaojun, Jixiang Guo, Dongtao Fei, Li Wang, Zhongying Peng, Jianmin Li y Jingfeng Dong. "Polymer surfactants as viscosity reducers for ultra-heavy oil: Synthesis and viscosity reduction mechanism". Fuel 357 (febrero de 2024): 129871. http://dx.doi.org/10.1016/j.fuel.2023.129871.
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Thamdrup, Bo, Ram�n Rossell�-Mora y Rudolf Amann. "Microbial Manganese and Sulfate Reduction in Black Sea Shelf Sediments". Applied and Environmental Microbiology 66, n.º 7 (1 de julio de 2000): 2888–97. http://dx.doi.org/10.1128/aem.66.7.2888-2897.2000.
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ABSTRACT The microbial ecology of anaerobic carbon oxidation processes was investigated in Black Sea shelf sediments from mid-shelf with well-oxygenated bottom water to the oxic-anoxic chemocline at the shelf-break. At all stations, organic carbon (Corg) oxidation rates were rapidly attenuated with depth in anoxically incubated sediment. Dissimilatory Mn reduction was the most important terminal electron-accepting process in the active surface layer to a depth of ∼1 cm, while SO4 2− reduction accounted for the entire Corg oxidation below. Manganese reduction was supported by moderately high Mn oxide concentrations. A contribution from microbial Fe reduction could not be discerned, and the process was not stimulated by addition of ferrihydrite. Manganese reduction resulted in carbonate precipitation, which complicated the quantification of Corg oxidation rates. The relative contribution of Mn reduction to Corg oxidation in the anaerobic incubations was 25 to 73% at the stations with oxic bottom water. In situ, where Mn reduction must compete with oxygen respiration, the contribution of the process will vary in response to fluctuations in bottom water oxygen concentrations. Total bacterial numbers as well as the detection frequency of bacteria with fluorescent in situ hybridization scaled to the mineralization rates. Most-probable-number enumerations yielded up to 105 cells of acetate-oxidizing Mn-reducing bacteria (MnRB) cm−3, while counts of Fe reducers were <102 cm−3. At two stations, organisms affiliated with Arcobacter were the only types identified from 16S rRNA clone libraries from the highest positive MPN dilutions for MnRB. At the third station, a clone type affiliated with Pelobacter was also observed. Our results delineate a niche for dissimilatory Mn-reducing bacteria in sediments with Mn oxide concentrations greater than ∼10 μmol cm−3 and indicate that bacteria that are specialized in Mn reduction, rather than known Mn and Fe reducers, are important in this niche.
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Blaszczak, Wiktoria, Wojciech Barczak, Julia Masternak, Przemysław Kopczyński, Anatoly Zhitkovich y Błażej Rubiś. "Vitamin C as a Modulator of the Response to Cancer Therapy". Molecules 24, n.º 3 (28 de enero de 2019): 453. http://dx.doi.org/10.3390/molecules24030453.
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Ascorbic acid (vitamin C) has been gaining attention as a potential treatment for human malignancies. Various experimental studies have shown the ability of pharmacological doses of vitamin C alone or in combinations with clinically used drugs to exert beneficial effects in various models of human cancers. Cytotoxicity of high doses of vitamin C in cancer cells appears to be related to excessive reactive oxygen species generation and the resulting suppression of the energy production via glycolysis. A hallmark of cancer cells is a strongly upregulated aerobic glycolysis, which elevates its relative importance as a source of ATP (Adenosine 5′-triphosphate). Aerobic glycolysis is maintained by a highly increased uptake of glucose, which is made possible by the upregulated expression of its transporters, such as GLUT-1, GLUT-3, and GLUT-4. These proteins can also transport the oxidized form of vitamin C, dehydroascorbate, permitting its preferential uptake by cancer cells with the subsequent depletion of critical cellular reducers as a result of ascorbate formation. Ascorbate also has a potential to affect other aspects of cancer cell metabolism due to its ability to promote reduction of iron(III) to iron(II) in numerous cellular metalloenzymes. Among iron-dependent dioxygenases, important targets for stimulation by vitamin C in cancer include prolyl hydroxylases targeting the hypoxia-inducible factors HIF-1/HIF-2 and histone and DNA demethylases. Altered metabolism of cancer cells by vitamin C can be beneficial by itself and promote activity of specific drugs.
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Maltby, Johanna, Lea Steinle, Carolin R. Löscher, Hermann W. Bange, Martin A. Fischer, Mark Schmidt y Tina Treude. "Microbial methanogenesis in the sulfate-reducing zone of sediments in the Eckernförde Bay, SW Baltic Sea". Biogeosciences 15, n.º 1 (10 de enero de 2018): 137–57. http://dx.doi.org/10.5194/bg-15-137-2018.
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Abstract. Benthic microbial methanogenesis is a known source of methane in marine systems. In most sediments, the majority of methanogenesis is located below the sulfate-reducing zone, as sulfate reducers outcompete methanogens for the major substrates hydrogen and acetate. The coexistence of methanogenesis and sulfate reduction has been shown before and is possible through the usage of noncompetitive substrates by methanogens such as methanol or methylated amines. However, knowledge about the magnitude, seasonality, and environmental controls of this noncompetitive methane production is sparse. In the present study, the presence of methanogenesis within the sulfate reduction zone (SRZ methanogenesis) was investigated in sediments (0–30 cm below seafloor, cm b.s.f.) of the seasonally hypoxic Eckernförde Bay in the southwestern Baltic Sea. Water column parameters such as oxygen, temperature, and salinity together with porewater geochemistry and benthic methanogenesis rates were determined in the sampling area Boknis Eck quarterly from March 2013 to September 2014 to investigate the effect of seasonal environmental changes on the rate and distribution of SRZ methanogenesis, to estimate its potential contribution to benthic methane emissions, and to identify the potential methanogenic groups responsible for SRZ methanogenesis. The metabolic pathway of methanogenesis in the presence or absence of sulfate reducers, which after the addition of a noncompetitive substrate was studied in four experimental setups: (1) unaltered sediment batch incubations (net methanogenesis), (2) 14C-bicarbonate labeling experiments (hydrogenotrophic methanogenesis), (3) manipulated experiments with the addition of either molybdate (sulfate reducer inhibitor), 2-bromoethanesulfonate (methanogen inhibitor), or methanol (noncompetitive substrate, potential methanogenesis), and (4) the addition of 13C-labeled methanol (potential methylotrophic methanogenesis). After incubation with methanol, molecular analyses were conducted to identify key functional methanogenic groups during methylotrophic methanogenesis. To also compare the magnitudes of SRZ methanogenesis with methanogenesis below the sulfate reduction zone (> 30 cm b.s.f.), hydrogenotrophic methanogenesis was determined by 14C-bicarbonate radiotracer incubation in samples collected in September 2013.SRZ methanogenesis changed seasonally in the upper 30 cm b.s.f. with rates increasing from March (0.2 nmol cm−3 d−1) to November (1.3 nmol cm−3 d−1) 2013 and March (0.2 nmol cm−3 d−1) to September (0.4 nmol cm−3 d−1) 2014. Its magnitude and distribution appeared to be controlled by organic matter availability, C / N, temperature, and oxygen in the water column, revealing higher rates in the warm, stratified, hypoxic seasons (September–November) compared to the colder, oxygenated seasons (March–June) of each year. The majority of SRZ methanogenesis was likely driven by the usage of noncompetitive substrates (e.g., methanol and methylated compounds) to avoid competition with sulfate reducers, as was indicated by the 1000–3000-fold increase in potential methanogenesis activity observed after methanol addition. Accordingly, competitive hydrogenotrophic methanogenesis increased in the sediment only below the depth of sulfate penetration (> 30 cm b.s.f.). Members of the family Methanosarcinaceae, which are known for methylotrophic methanogenesis, were detected by PCR using Methanosarcinaceae-specific primers and are likely to be responsible for the observed SRZ methanogenesis.The present study indicates that SRZ methanogenesis is an important component of the benthic methane budget and carbon cycling in Eckernförde Bay. Although its contributions to methane emissions from the sediment into the water column are probably minor, SRZ methanogenesis could directly feed into methane oxidation above the sulfate–methane transition zone.
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Nakamura, Shinji, Masahiro Kamaura, Yuichiro Akao, Natsuko Nakamura, Atsushi Mizukami, Akihiko Goto, Naoki Furuyama, Nobuo Cho y Shizuo Kasai. "Discovery of phenylpyrrolidine derivatives as a novel class of retinol binding protein 4 (RBP4) reducers". Bioorganic & Medicinal Chemistry 54 (enero de 2022): 116553. http://dx.doi.org/10.1016/j.bmc.2021.116553.
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Charewicz, Witold A., Jerzy Wódka y Tomasz Chmielewski. "Recovery of rhenium from acidic aqueous solutions by pressure reduction with gaseous reducers". Journal of Chemical Technology & Biotechnology 52, n.º 1 (24 de abril de 2007): 119–26. http://dx.doi.org/10.1002/jctb.280520109.
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Bhattacharya, Sabyasachi, Tarunendu Mapder, Svetlana Fernandes, Chayan Roy, Jagannath Sarkar, Moidu Jameela Rameez, Subhrangshu Mandal et al. "Sedimentation rate and organic matter dynamics shape microbiomes across a continental margin". Biogeosciences 18, n.º 18 (23 de septiembre de 2021): 5203–22. http://dx.doi.org/10.5194/bg-18-5203-2021.
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Abstract. Marine sedimentation rate and bottom-water O2 concentration control organic carbon remineralization and sequestration across continental margins, but whether and how they shape microbiome architecture (the ultimate effector of all biogeochemical phenomena) across shelf and slope sediments is still unclear. Here we reveal distinct microbiome structures and functions, amidst comparable pore fluid chemistries, along 300 cm sediment horizons underlying the seasonal (shallow coastal; water depth: 31 m) and perennial (deep sea; water depths: 530 and 580 m) oxygen minimum zones (OMZs) of the Arabian Sea, situated across the western Indian margin. The sedimentary geomicrobiology was elucidated by analyzing metagenomes, metatranscriptomes, enrichment cultures, and depositional rates measured via radiocarbon and lead excess dating; the findings were then evaluated in light of the other geochemical data available for the cores. Along the perennial-OMZ sediment cores, microbial communities were dominated by Gammaproteobacteria and Alphaproteobacteria, but in the seasonal-OMZ core communities were dominated by Euryarchaeota and Firmicutes. As a perennial-OMZ signature, a cryptic methane production–consumption cycle was found to operate near the sediment surface, within the sulfate reduction zone; overall diversity, as well as the relative abundances of anaerobes requiring simple fatty acids (methanogens, anaerobic methane oxidizers, sulfate reducers, and acetogens), peaked in the topmost sediment layer and then declined via synchronized fluctuations until the sulfate–methane transition zone was reached. The microbiome profile was completely reversed in the seasonal-OMZ sediment horizon. In the perennial-OMZ sediments, deposited organic carbon was higher in concentration and rich in marine components that degrade readily to simple fatty acids; simultaneously, lower sedimentation rate afforded higher O2 exposure time for organic matter degradation despite perennial hypoxia in the bottom water. The resultant abundance of reduced carbon substrates eventually sustained multiple inter-competing microbial processes in the upper sediment layers. The entire geomicrobial scenario was opposite in the sediments of the seasonal OMZ. These findings create a microbiological baseline for understanding carbon–sulfur cycling in distinct depositional settings and water column oxygenation regimes across the continental margins.
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Gier, Jessica, Stefan Sommer, Carolin R. Löscher, Andrew W. Dale, Ruth A. Schmitz y Tina Treude. "Nitrogen fixation in sediments along a depth transect through the Peruvian oxygen minimum zone". Biogeosciences 13, n.º 14 (18 de julio de 2016): 4065–80. http://dx.doi.org/10.5194/bg-13-4065-2016.
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Abstract. The potential coupling of nitrogen (N2) fixation and sulfate reduction (SR) was explored in sediments of the Peruvian oxygen minimum zone (OMZ). Sediment samples were retrieved by a multiple corer at six stations along a depth transect (70–1025 m water depth) at 12° S, covering anoxic and hypoxic bottom water conditions. Benthic N2 fixation, determined by the acetylene reduction assay, was detected at all sites, with highest rates between 70 and 253 m and lower rates at greater depth. SR rates decreased with increasing water depth. N2 fixation and SR overlapped in sediments, suggesting a potential coupling of both processes. However, a weak positive correlation of their activity distribution was detected by principle component analysis. A potential link between N2 fixation and sulfate-reducing bacteria was indicated by the molecular analysis of nifH genes. Detected nifH sequences clustered with the sulfate-reducing bacteria Desulfonema limicola at the 253 m station. However, nifH sequences of other stations clustered with uncultured organisms, Gammaproteobacteria, and Firmicutes (Clostridia) rather than with known sulfate reducers. The principle component analysis revealed that benthic N2 fixation in the Peruvian OMZ is controlled by organic matter (positive) and free sulfide (negative). No correlation was found between N2 fixation and ammonium concentrations (even at levels > 2022 µM). N2 fixation rates in the Peruvian OMZ sediments were in the same range as those measured in other organic-rich sediments.
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Kutovaya, O. V., A. M. Grebennikov, A. K. Tkhakakhova, V. A. Isaev, V. M. Garmashov, V. A. Bespalov, Yu I. Cheverdin y V. P. Belobrov. "The changes in soil-biological processes and structure of microbial community of agrochernozems in conditions of different ways of soil cultivation". Dokuchaev Soil Bulletin, n.º 92 (1 de mayo de 2018): 35–61. http://dx.doi.org/10.19047/0136-1694-2018-92-35-61.
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The impact of soil cultivation methods (tillage with soil overturning at a depth of 20-22 and 14-16 cm, beardless plowing and surface treatment respectively at a depth of 14-16 and 6-8 cm, and also zero or minimal tillage)) on biological activity of various ecology-trophic groups of microorganisms on agronochernozems of the Kamennaya Steppe (Voronezh oblast) using classical inoculation methods on elective media. It is shown that chernozems are highly resistant soils that are resistant to external impacts, preserving high biological activity even at the maximum mechanical treatment. Tillage with soil overturn leads to aeration of the arable horizon and the activity initiation of aerobic microorganisms of the carbon cycle, responsible for the mineralization of both complex and simple organic compounds of the soil. The contribution of microorganisms of the nitrogen cycle (nitrate-reducers and nitrogen fixers) to the overall biological activity of migratory-micellar chernozems of arable land and layland was minimal. The level of mechanical impact on the soil affects the quantitative indices and biological activity of microorganisms in the soil - the stronger the effect, the deeper layers are affected. The processes of entrance for fresh organic matter prevail over the processes of mineralization practically in all variants of the experiment, except for tillage with the soil overturn to a depth of 14-16 cm, as indicated by the values of the mineralization coefficients. The strongest humus-accumulative effect was observed in the variant with zero treatment, which is maximally approximated to such processes, occurred in a layland. Minimal soil cultivation will help to preserve the unique structure of chernozem soil, to increase the flow of fresh organic remains, to preserve the high biological diversity which is specific for natural biocenosises.
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Messner, Katia y Vladimir Yurkov. "Abundance, Characterization and Diversity of Culturable Anoxygenic Phototrophic Bacteria in Manitoban Marshlands". Microorganisms 12, n.º 5 (17 de mayo de 2024): 1007. http://dx.doi.org/10.3390/microorganisms12051007.
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Marshes are an important ecosystem, acting as a biodiversity hotspot, a carbon sink and a bioremediation site, breaking down anthropogenic waste such as antibiotics, metals and fertilizers. Due to their participation in these metabolic activities and their capability to contribute to primary productivity, the microorganisms in such habitats have become of interest to investigate. Since Proteobacteria were previously found to be abundant and the waters are well aerated and organic-rich, this study on the presence of anoxygenic phototrophic bacteria, purple non-sulfur bacteria and aerobic anoxygenic phototrophs in marshes was initiated. One sample was collected at each of the seven Manitoban sites, and anoxygenic phototrophs were cultivated and enumerated. A group of 14 strains, which represented the phylogenetic diversity of the isolates, was physiologically investigated further. Aerobic anoxygenic phototrophs and purple non-sulfur bacteria were present at each location, and they belonged to the α- and β-Proteobacteria subphyla. Some were closely related to known heavy metal reducers (Brevundimonas) and xenobiotic decomposers (Novosphingobium and Sphingomonas). All were able to synthesize the photosynthetic complexes aerobically. This research highlights the diversity of and the potential contributions that anoxygenic phototrophs make to the essential functions taking place in wetlands.
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Edmonds, Jennifer W., Nathanial B. Weston, Samantha B. Joye y Mary Ann Moran. "Variation in Prokaryotic Community Composition as a Function of Resource Availability in Tidal Creek Sediments". Applied and Environmental Microbiology 74, n.º 6 (11 de enero de 2008): 1836–44. http://dx.doi.org/10.1128/aem.00854-07.
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ABSTRACT In anaerobic coastal sediments, hydrolytic and/or fermentative bacteria degrade polymeric material and produce labile intermediates, which are used by terminal metabolizers to complete the conversion of organic material to CO2. We used molecular approaches to evaluate the response of two bacterial terminal metabolizer groups from a coastal tidal creek sediments, sulfate reducers and methanogens, to controlled changes in carbon resource supply. Tidal creek sediment bioreactors were established in April and August 2004. For each date, intact sediment sections were continuously supplied with flowthrough seawater that was either unamended or amended with the high-molecular-weight polysaccharide dextran. Biogeochemical data indicate that the activity of fermenting bacteria and the terminal metabolizers was limited by organic carbon supply during both experiments, with a significant increase in net volatile fatty acid (VFA) production and rates of sulfate reduction and methanogenesis following dextran addition. Community composition (measured by using terminal restriction fragment length polymorphism analysis, and functional gene [dsrA, mcrA] clone libraries) changed from April to August. However, community composition was not different between amended and unamended cores within each month, despite the change in resource level. Moreover, there was no relationship between community richness and evenness with resource level. This lack of variation in community composition with C addition could be attributed to the dynamic environment these sediment communities experience in situ. Fluctuations in VFA concentrations are most likely very high, so that the dominant bacterial species must be able to outcompete other species at both high and low resource levels.
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Stolyarchuk, Maxim, Julie Ledoux, Elodie Maignant, Alain Trouvé y Luba Tchertanov. "Identification of the Primary Factors Determining the Specificity of Human VKORC1 Recognition by Thioredoxin-Fold Proteins". International Journal of Molecular Sciences 22, n.º 2 (14 de enero de 2021): 802. http://dx.doi.org/10.3390/ijms22020802.
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Redox (reduction–oxidation) reactions control many important biological processes in all organisms, both prokaryotes and eukaryotes. This reaction is usually accomplished by canonical disulphide-based pathways involving a donor enzyme that reduces the oxidised cysteine residues of a target protein, resulting in the cleavage of its disulphide bonds. Focusing on human vitamin K epoxide reductase (hVKORC1) as a target and on four redoxins (protein disulphide isomerase (PDI), endoplasmic reticulum oxidoreductase (ERp18), thioredoxin-related transmembrane protein 1 (Tmx1) and thioredoxin-related transmembrane protein 4 (Tmx4)) as the most probable reducers of VKORC1, a comparative in-silico analysis that concentrates on the similarity and divergence of redoxins in their sequence, secondary and tertiary structure, dynamics, intraprotein interactions and composition of the surface exposed to the target is provided. Similarly, hVKORC1 is analysed in its native state, where two pairs of cysteine residues are covalently linked, forming two disulphide bridges, as a target for Trx-fold proteins. Such analysis is used to derive the putative recognition/binding sites on each isolated protein, and PDI is suggested as the most probable hVKORC1 partner. By probing the alternative orientation of PDI with respect to hVKORC1, the functionally related noncovalent complex formed by hVKORC1 and PDI was found, which is proposed to be a first precursor to probe thiol–disulphide exchange reactions between PDI and hVKORC1.
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Hua, Guan-Jie, Che-Lun Hung y Chuan Yi Tang. "Hadoop-MCC: Efficient Multiple Compound Comparison Algorithm Using Hadoop". Combinatorial Chemistry & High Throughput Screening 21, n.º 2 (17 de abril de 2018): 84–92. http://dx.doi.org/10.2174/1386207321666180102120641.
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Aim and Objective: In the past decade, the drug design technologies have been improved enormously. The computer-aided drug design (CADD) has played an important role in analysis and prediction in drug development, which makes the procedure more economical and efficient. However, computation with big data, such as ZINC containing more than 60 million compounds data and GDB-13 with more than 930 million small molecules, is a noticeable issue of time-consuming problem. Therefore, we propose a novel heterogeneous high performance computing method, named as Hadoop-MCC, integrating Hadoop and GPU, to copy with big chemical structure data efficiently. Materials and Methods: Hadoop-MCC gains the high availability and fault tolerance from Hadoop, as Hadoop is used to scatter input data to GPU devices and gather the results from GPU devices. Hadoop framework adopts mapper/reducer computation model. In the proposed method, mappers response for fetching SMILES data segments and perform LINGO method on GPU, then reducers collect all comparison results produced by mappers. Due to the high availability of Hadoop, all of LINGO computational jobs on mappers can be completed, even if some of the mappers encounter problems. Results: A comparison of LINGO is performed on each the GPU device in parallel. According to the experimental results, the proposed method on multiple GPU devices can achieve better computational performance than the CUDA-MCC on a single GPU device. Conclusion: Hadoop-MCC is able to achieve scalability, high availability, and fault tolerance granted by Hadoop, and high performance as well by integrating computational power of both of Hadoop and GPU. It has been shown that using the heterogeneous architecture as Hadoop-MCC effectively can enhance better computational performance than on a single GPU device.