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富里酸驱动发酵梭菌砷甲基化的代谢机制解析

环境科学学报 2024年第6期44卷 404-413页

作者：梁永美陈冠虹朱潇方利平李晓敏 Hemmat-Jou mohammad hossein 李芳柏华南师范大学环境研究院广东省化学品污染与环境安全重点实验室环境理论化学教育部重点实验室广州510006 广东省科学院生态环境与土壤研究所广东省农业环境综合治理重点实验室广州510650 华南师范大学环境学院广州510006 中国科学院广州地球化学研究所广州510640

微生物介导砷甲基化是砷生物地球化学循环中的重要过程.已有研究表明,腐殖质添加能促进稻田土壤厌氧微生物砷甲基化,但其关键机制尚不明确.本研究以砷污染稻田土壤中分离的一株砷甲基化功能厌氧发酵梭菌Clostridium sporogenes LHA6为对... 详细信息

微生物介导砷甲基化是砷生物地球化学循环中的重要过程.已有研究表明,腐殖质添加能促进稻田土壤厌氧微生物砷甲基化,但其关键机制尚不明确.本研究以砷污染稻田土壤中分离的一株砷甲基化功能厌氧发酵梭菌Clostridium sporogenes LHA6为对象,探究富里酸对梭菌细胞代谢活性的影响,并解析其与砷甲基化效率的内在关系.结果表明,相比对照处理,特定浓度(0.5~2 g·L^(-1))富里酸处理中菌株LHA6的水溶态和细胞结合态甲基砷生成量分别增加25.7%~84.4%和39.8%~60.4%,挥发性甲基砷产物增加0.68~1.86倍,主要产物形态为二甲基砷及其氢化物.综合电化学、代谢物和基因表达定量等方法证实:富里酸可作为胞外电子受体,抑制梭菌胞内发酵产氢活性,增加NADH/NAD+比率;同时,富里酸存在时梭菌显著上调S-腺苷甲硫氨酸(SAM)合成相关基因转录活性,增强SAM合成代谢通量,很可能是富里酸促进梭菌产生甲基砷及其氢化物的关键机制.本研究系统揭示了富里酸调控梭菌细胞代谢,进而强化其砷甲基化及挥发的砷解毒机制,获得了对砷的生物地球化学循环的新认知,有望为土壤砷污染控制提供新思路.

关键词：砷甲基化砷挥发发酵梭菌富里酸产氢

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电子穿梭体介导土壤锑还原成矿的微生物机制

生态环境学报 2024年第2期33卷 272-281页

作者：蓝浚陈冠虹张俊涛 Hemmat-Jou mohammad hossein 舒小华方利平李芳柏桂林理工大学环境科学与工程学院广西桂林541000 广东省科学院生态环境与土壤研究所/广东省农业环境综合治理重点实验室广东广州510650 广州市林业和园林科学研究院广东广州510405

微生物锑还原成矿有助于降低土壤锑的生物有效性和移动性,是土壤锑污染修复的重要策略之一。电子穿梭体AQDS能够加速土壤富集菌群锑还原速率,可能与其促进微生物呼吸及细胞生长有关。理解电子穿梭体(ES)介导微生物锑还原过程与机制可为... 详细信息

微生物锑还原成矿有助于降低土壤锑的生物有效性和移动性,是土壤锑污染修复的重要策略之一。电子穿梭体AQDS能够加速土壤富集菌群锑还原速率,可能与其促进微生物呼吸及细胞生长有关。理解电子穿梭体(ES)介导微生物锑还原过程与机制可为土壤锑污染控制提供关键理论支撑。醌类和黄素类电子穿梭体(AQDS和FMN)存在时可能改变微生物呼吸代谢中的电子传递过程,然而ES介导下的微生物锑还原过程及转录响应机制尚不清楚。利用锑污染稻田土壤分离的兼性厌氧锑还原细菌Mesobacillus jeotgali PS1作为研究对象,探究醌类和黄素类电子穿梭体(AQDS和FMN)对菌株PS1锑还原过程及关键功能基因转录活性的影响。结果表明,菌株PS1驱动Sb(Ⅴ)还原为Sb(Ⅲ)过程中水溶态Sb(Ⅲ)随培养时间先累积后下降,培养72 h后水溶态锑去除率为64%,生成十四面体方锑矿,表明菌株PS1驱动锑还原成矿有助于锑的钝化。两种ES能够加速细菌锑还原反应,而对胞外生成的方锑矿晶型没有影响。通过定量分析菌株PS1潜在功能基因转录表达活性,结果表明AQDS相比FMN更能促进菌株PS1细胞膜二甲基亚砜还原酶(DMSOR)基因和胞内解毒型砷还原基因(arsC)转录活性,有助于增加菌株PS1呼吸代谢活性和胞内锑解毒从而加速锑还原,所以AQDS可能在强化微生物锑还原钝化中更具有优势。该研究揭示了不同电子穿梭体介导锑还原的微生物机制,为锑污染土壤生物修复提供重要理论支撑。

关键词：锑还原细菌电子穿梭体方锑矿锑解毒转录响应二甲基亚砜还原酶

Modeling of liquid hydrocarbon products from syngas

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International Journal of Coal Science & Technology 2019年第1期6卷 27-36页

作者： hossein Atashi Mohsen Hajisafari Fatemeh rezaeian mohammad Javad Parnian Department of Chemical Engineering University of Sistan and Baluchestan ZahedanIran School of Chemical Engineering Iran University of Science and TechnologyTehranIran

The modeling of hydrocarbon selectivity and CO conversion of the Fischer-Tropsch synthesis over Fe-Ni/Al2O3 catalyst by using coupled artificial neural networks (ANN) and design of experiment (DOE) approaches were investigated. The variable parameters for modeling consisted of the pressure range between 2 and 10 bar and the temperature range of 523-573 K. After training of data by ANN and determination of DOE points by central composite design (CCD), the results were compiled together for producing simulated data used in the response surface method (RSM). The RSM was used as an applied mathematics model to dem on strate the CO conversi on and selectivity of hydrocarbons depende nee on the CO hydrogenation conditions. The results indicated that CO conversion and Cg selectivity increased with rising both temperature and pressure. The methane selectivity showed upward trend as the temperature in creased. It also in creased by decreasing pressure. Finally, the optimization of the catalytic process was carried out and conditions with maximum desired product were obtained. A comparison of experimental values and RSM values show that the RSM equations are able to predict the behavior of experimental data.

关键词： Fischer-Tropsch synthesis Artificial neural network Response surface method CO conversion Hydrocarbon selectivity

Resilience-oriented intentional islanding of reconfigurable distribution power systems

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Journal of Modern Power Systems and Clean Energy 2019年第4期7卷 741-752页

作者： mohammad hossein OBOUDI mohammad mohammadI mohammad RASTEGAR Department of Power and Control Engineering School of Electrical and Computer EngineeringShiraz UniversityShirazIran

The participation of distributed energy resources in the load restoration procedure,known as intentional islanding,can significantly improve the distribution system *** system reconfiguration can effectively alter islanding procedure and thus provide an opportunity to supply more demanded energy and reduce distribution system *** addition,high-impact events such as hurricanes and earthquakes may complicate the procedure of load restoration,due to the disconnection of the distribution system from the upstream grid or concurrent component *** paper presents a two-level method for intentional islanding of a reconfigurable distribution system,considering high-impact *** thefirst level,optimal islands are selected according to the graph model of the distribution *** the second level,an optimal power flow(OPF)problem is solved to meet the operation constraints of the islands by reactive power control and demand side *** proposed problem in the first level is solved by a combination of depth first search and particle swarm optimization *** OPF problem in the second level is solved in DIgSILENT *** proposed method is implemented in the IEEE 69-bus test system,and the results show the validity and effectiveness of the proposed algorithm.

关键词： Intentional islanding Active distribution system Distributed energy resource Distribution system reconfiguration Distribution system resilience

TRANSVERSE VIBRATION OF A HANGING NONUNIFORM NANOSCALE TUBE BASED ON NONLOCAL ELASTICITY THEORY WITH SURFACE EFFECTS

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Acta Mechanica Solida Sinica 2014年第2期27卷 202-209页

作者： hossein Roostai mohammad Haghpanahi Department of Mechanical Engineering Iran University of Science & Technology (IUST)

The aim of this paper is to study the free transverse vibration of a hanging nonuni- form nanoscale tube. The analysis procedure is based on nonlocal elasticity theory with surface effects. The nonlocal elasticity theory states that the stress at a point is a function of strains at all points in the continuum. This theory becomes significant for small-length scale objects such as micro- and nanostructures. The effects of nonlocality, surface energy and axial force on the natural frequencies of the nanotube are investigated. In this study, analytical solutions are formulated for a clamped-free Euler-Bernoulli beam to study the free vibration of nanoscale tubes.

关键词： nonlocal elasticity theory vibration surface effects nanoscale tube

Fabrication of phosphor bronze/Al two-phase material by recycling phosphor bronze chips using hot extrusion process and investigation of their microstructural and mechanical properties

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International Journal of Minerals,Metallurgy and Materials 2020年第6期27卷 809-817页

作者： Majid hosseini mohammad hossein Paydar Department of Materials Science and Engineering School of EngineeringShiraz UniversityShiraz 71964-84334Iran

Despite the existence of conventional methods for recycling chips,solid-state techniques have become popular,whereby waste metals are directly recycled into consolidated products with the desired shapes and *** investigated the feasibility of recycling phosphor bronze chips through a hot extrusion process using aluminum powder as a metal binder for the fabrication of a metal-fiber-reinforced aluminum matrix *** do so,mixtures containing 20 vol%–50 vol%of chips were prepared,cold-compacted,and *** quality of the consolidated samples was evaluated by determining the density of the fabricated composites and studying their *** addition,we performed tensile and hardness tests to evaluate the mechanical properties of the fabricated *** also analyzed the fracture surfaces of the samples to study the fracture mechanism as a function of the volume fraction of phosphor bronze chips in the fabricated *** results indicated that the most effective consolidation occurred in the sample containing 20 vol%of chips extruded at 465℃in which the chips serve as ideal fibers for improving the mechanical properties,especially the ultimate tensile strength,in comparison with those of Al matrixes that contain no chips but are produced under the same conditions.

关键词： recycling hot extrusion metal–metal composite phosphor bronze chips aluminum powder

Finding buckling points for nonlinear structures by dynamic relaxation scheme

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Frontiers of Structural and Civil Engineering 2020年第1期14卷 23-61页

作者： mohammad REZAIEE-PAJAND hossein ESTIRI Civil Engineering Department Ferdowsi University of MashhadMashhad 91775-1111Iran

Dynamic Relaxation Method(DRM)is an explicit approach for solving the simultaneous systems of *** this tactic,the fictitious mass and damping are added to the static governing equations,and an artificial dynamic system is *** using DRM for nonlinear analysis,the structural static equilibrium path is *** outcome is extremely valuable,since it leads to the behavior of *** the finding related to the structural static path are the critical and buckling points for nonlinear *** this paper,a new way for calculating the load factor is proposed by setting the external work *** the dynamic relaxation scheme with external work technique has not been formulated so *** all incremental-iterative methods,the load factor increment sign should be determinated by extra *** sign leads to increase or decrease of the load *** is worth emphasizing that sign of the load factor increment changes at the load limit ***,the sign determinations are required in the common work control *** disadvantages are eliminated in the proposed *** fact,the suggested load factor depends only on the Dynamic Relaxation(DR)fictitious ***,all DR calculations are performed via vector ***,the load factor is calculated only by one formula,and it has the same relation in the all solution *** contrast to the arc length techniques,which requires the sign determined,the proposed scheme does not need any sign *** is shown that author’s technique is quicker than the other dynamic relaxation *** prove the capability and efficiency of the presented scheme,several numerical tests are *** results indicate that the suggested approach can trace the complex structural static paths,even in the snap-back and snap-through parts.

关键词： load factor external work dynamic relaxation static equilibrium path large displacement

An Alternative Technique for Compounding and Fabrication of Lithium Ion Conductive PVB Films with Enhanced Thermal Properties and Electrochromic Performance

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Chinese Journal of Polymer Science 2022年第10期40卷 1213-1222,I0009页

作者： mohammad hossein Azarian Jatuphorn Wootthikanokkhan Materials Technology Program School of EnergyEnvironment and MaterialsKing Mongkut's University of Technology ThonburiBangkok 10140Thailand

This research concerns the development of lithium ions conductive electrolyte from poly(vinyl butyral)(PVB)resin for use as a special interlayer film in electrochromic *** obtain the final PVB film with high ionic conductivity and thermal stability,a masterbatch was firstly prepared by mixing of PVB resin with lithium salt(LiClO_(4))and additives in an aqueous ethanol *** this,the dried masterbatch were converted into final films by an extrusion *** this study,PVB film with the highest ionic conductivity value of 4.85×10^(-6) was obtained when the masterbatch was diluted with the neat PVB resin at the weight ratio of 2:1 in the extruder prior to *** results from cyclic voltammetry over 100 cycles,showed that performance of the electrochromic device(ITO/WO_(3)/PVB electrolyte/ITO)fabricated by using the above PVB film is stable and *** overall,this work demonstrates that ion conductive PVB films with compromised ionic conductivity and thermal stability can be prepared via an extrusion process without the need to modify chemical structure of *** was carried out through the masterbatch approach,by introducing (LiClO_(4)) salts into the plasticized PVB via a solution mixing process prior to converting it into a final film via the extrusion process.

关键词： Ionic conductivity Poly(vinyl butyral) Masterbatch mixing Solid polymer electrolyte Electrochromic glass Safety glass

A simulation study on p-doping level of polymer host material in P3HT:PCBM bulk heterojunction solar cells

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Chinese Physics B 2017年第4期26卷 508-512页

作者： hossein Movla mohammad Babazadeh Azar Aytash Co. Technology IncubatorUniversity of TabrizTabrizIran

In this study,we investigate the influence of doping on the charge transfer and device characteristics parameters in the bulk heterojunction solar cells based on poly（3-hexylthiophene）（P3HT） and a methanofuUerene derivative（PCBM）.Organic semiconductors are also known to be not pure and they have defects and impurities,some of them are being charged and act as p-type or n-type *** of the solar cell characteristics parameters versus the p-doping level have been done at three different n-dopings（N_d） that consist of 5 × 10^（17） cm^（-3）,10^（18） cm^（-3）,and 5 × 10^（18） cm^（-3）.We perform the analysis of the doping concentration through the drift-diffusion model,and calculate the current and voltage doping *** find that at three different n-dopant levels,optimum p-type doping is about N_p = 6 × 10^（18） cm^（-3）.Simulation results have shown that by increasing doping level,V_（oc） monotonically increases by *** efficiency reaches its maximum at somewhat higher doping as FF has its peak at N_p = 3 × 10^（18） cm^（-3）.Moreover,this paper demonstrates that the optimum value for the p-doping is about N_p = 6 × 10^（18） cm^（-3） and optimum value for n-dopant is N_d = 10^（18） cm^（-3）,*** simulated results confirm that doping considerably affects the performance of organic solar cells.

关键词： organic photovoltaics charge transport doping finite difference method