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Nitrifying population dynamics in a redox stratified membrane biofilm reactor (RSMBR) for treating ammonium-rich

Rongchang WANG, Xinmin ZHAN, Yalei ZHANG, Jianfu ZHAO

《环境科学与工程前沿（英文）》 2011年 第5卷 第1期   页码 48-56 doi: 10.1007/s11783-011-0305-7

摘要： Nitrogen removal performance and nitrifying population dynamics were investigated in a redox stratified membrane biofilm reactor (RSMBR) under oxygen limited condition to treat ammonium-rich wastewater. When the loading rate increased from 11.1±1.0 to , the nitrogen removal in the RSMBR system increased from 18.0±9.6 mgN·d to 128.9±61.7 mgN·d . Shortcut nitrogen removal was achieved with nitrite accumulation of about . Confocal micrographs showed the stratified distributions of nitrifiers and denitrifiers in the membrane aerated biofilms (MABs) at day 120, i.e., ammonia and nitrite oxidizing bacteria (AOB and NOB) were dominant in the region adjacent to the membrane, while heterotrophic bacteria propagated at the top of the biofilm. Real-time qPCR results showed that the abundance of gene was two orders of magnitude higher than the abundance of gene in the MABs. However, the gene was always detected during the operation time, which indicates the difficulty of complete washout of NOB in MABs. The growth of heterotrophic bacteria compromised the dominance of nitrifiers in biofilm communities, but it enhanced the denitrification performance of the RSMBR system. Applying a high ammonia loading together with oxygen limitation was found to be an effective way to start nitrite accumulation in MABs, but other approaches were needed to sustain or improve the extent of nitritation in nitrogen conversion in MABs.

关键词： ammonium-rich wastewater     membrane biofilm reactor     nitrification     redox stratification     shortcut nitrogen removal    

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A methodology for regulating fuel stratification and improving fuel economy of GCI mode via double main-injection

《能源前沿（英文）》 2023年 第17卷 第5期   页码 678-691 doi: 10.1007/s11708-022-0859-z

摘要： Gasoline compression ignition (GCI) combustion faces problems such as high maximum pressure rise rate (MPRR) and combustion deterioration at high loads. This paper aims to improve the engine performance of the GCI mode by regulating concentration stratification and promoting fuel-gas mixing by utilizing the double main-injection (DMI) strategy. Two direct injectors simultaneously injected gasoline with an octane number of 82.7 to investigate the energy ratio between the two main-injection and exhaust gas recirculation (EGR) on combustion and emissions. High-load experiments were conducted using the DMI strategy and compared with the single main-injection (SMI) strategy and conventional diesel combustion. The results indicate that the DMI strategy have a great potential to reduce the MPRR and improve the fuel economy of the GCI mode. At a 10 bar indicated mean effective pressure, increasing the main-injection-2 ratio (Rm-2) shortens the injection duration and increases the mean mixing time. Optimized Rm-2 could moderate the trade-off between the MPRR and the indicated specific fuel consumption with both reductions. An appropriate EGR should be adopted considering combustion and emissions. The DMI strategy achieves a highly efficient and stable combustion at high loads, with an indicated thermal efficiency (ITE) greater than 48%, CO and THC emissions at low levels, and MPRR within a reasonable range. Compared with the SMI strategy, the maximum improvement of the ITE is 1.5%, and the maximum reduction of MPRR is 1.5 bar/°CA.

关键词： gasoline compression ignition     injection strategy     fuel stratification     high efficiency     high load    

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Comparison of prechilling stratification and sulfuric acid scarification on seed germination of

Nan WANG, Jing GAO, Suiqi ZHANG, Feng YAN

《农业科学与工程前沿（英文）》 2017年 第4卷 第2期   页码 220-227 doi: 10.15302/J-FASE-2017146

摘要： In semi-arid regions of the Loess Plateau, water deficiency restricts plant performance. (switchgrass), which is a highly versatile grass, had been introduced to the Plateau as a restoration species. To determine if prechilling stratification (PCS) and sulfuric acid scarification (SAS) can optimize establishment, cvs Pathfinder, Trailblazer and Alamo were tested under different ambient water potentials by measuring germination and root and shoot growth along water potential gradients under laboratory conditions. Both PCS and SAS improved total germination percentage (TGP), with PCS being more beneficial. The effect of PCS and SAS on mean germination time (MGT) weakened gradually with increasing drought stress. Both PCS and SAS showed no obvious effect on promoting root and shoot growth. Both PCS and SAS reduced base water potential requirement for reaching 50% germination of Pathfinder and Trailblazer, with this effect greater for PCS. These results indicate that embryo dormancy may be a major factor limiting germination of under drought conditions. Pathfinder appears to be more suitable for a semi-arid environment, whereas Alamo appears to be unsuitable for drought conditions. Given the large difference between predicted value and measured value, the reliability and applicable scope of linear regression estimated Y needs further investigation, specification and optimization.

关键词： base water potential     data analysis method     embryo growth     germination    

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Photoreduction adjusted surface oxygen vacancy of BiMoO for boosting photocatalytic redox performance

《化学科学与工程前沿（英文）》 2023年 第17卷 第12期   页码 1937-1948 doi: 10.1007/s11705-023-2353-5

摘要： In this study, Bi2MoO6 with adjustable rich oxygen vacancies was prepared by a novel and simple solvothermal-photoreduction method which might be suitable for a large-scale production. The experiment results show that Bi2MoO6 with rich oxygen vacancies is an excellent photocatalyst. The photocatalytic ability of BMO-10 is 0.3 and 3.5 times higher than that of the pristine Bi2MoO6 for Rhodamine B degradation and Cr(VI) reduction, respectively. The results display that the band energy of the samples with oxygen vacancies was narrowed and the light absorption was broadened. Meanwhile, the efficiency of photogenerated electron-holes was increased and the separation and transfer speed of photogenerated carriers were improved. Therefore, this work provides a convenient and efficient method to prepare potential adjustable oxygen vacancy based photocatalysts to eliminate the pollution of dyes and Cr(VI) in water.

关键词： Bi2MoO6     oxygen vacancies     photoreduction     Cr(VI)     RhB    

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High butanol production by regulating carbon, redox and energy in Clostridia? ?

Jianfa Ou,Chao Ma,Ningning Xu,Yinming Du,Xiaoguang (Margaret) Liu

《化学科学与工程前沿（英文）》 2015年 第9卷 第3期   页码 317-323 doi: 10.1007/s11705-015-1522-6

摘要： Butanol is a promising biofuel with high energy intensity and can be used as gasoline substitute. It can be produced as a sustainable energy by microorganisms (such as Clostridia) from low-value biomass. However, the low productivity, yield and selectivity in butanol fermentation are still big challenges due to the lack of an efficient butanol-producing host strain. In this article, we systematically review the host cell engineering of Clostridia, focusing on (1) various strategies to rebalance metabolic flux to achieve a high butanol production by regulating the metabolism of carbon, redox or energy, (2) the challenges in pathway manipulation, and (3) the application of proteomics technology to understand the intracellular metabolism. In addition, the process engineering is also briefly described. The objective of this review is to summarize the previous research achievements in the metabolic engineering of and provide guidance for future novel strain construction to effectively produce butanol.

关键词： Clostridia     butanol     biofuel     metabolism     carbon     redox     energy    

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Characterization and comparison of organic functional groups effects on electrolyte performance for vanadium redox

《化学科学与工程前沿（英文）》 2023年 第17卷 第9期   页码 1221-1230 doi: 10.1007/s11705-023-2298-8

摘要： The vanadium redox flow battery with a safe and capacity-controllable large-scale energy storage system offers a new method for the sustainability. In this case, acetic acid, methane sulfonic acid, sulfonic acid, amino methane sulfonic acid, and taurine are used to overcome the low electrolyte energy density and stability limitations, as well as to investigate the effects of various organic functional groups on the vanadium redox flow battery. When compared to the pristine electrolyte (0.22 Ah, 5.0 Wh·L–1, 85.0%), the results show that taurine has the advantage of maintaining vanadium ion concentrations, discharge capacity (1.43 Ah), energy density (33.9 Wh·L–1), and energy efficiency (90.5%) even after several cycles. The acetic acid electrolyte is more conducive to the low-temperature stability of the V(II) electrolyte (177 h at −25 °C) than pristine (82 h at −2 °C). The –SO3H group, specifically the coaction of the –NH2 and –SO3H groups, improves electrolyte stability. The –NH2 and –COOH additive groups improved conductivity and electrochemical activity.

关键词： vanadium redox flow battery     functional groups     organic additives     energy density     stability    

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Risk stratification system for skin and soft tissue infections after allogeneic hematopoietic stem cell

《医学前沿（英文）》 2022年 第16卷 第6期   页码 957-968 doi: 10.1007/s11684-021-0910-1

摘要： Skin and soft tissue infections (SSTIs) refer to infections involving the skin, subcutaneous tissue, fascia, and muscle. In transplant populations with hematological malignancies, an immunocompromised status and the routine use of immunosuppressants increase the risk of SSTIs greatly. However, to date, the profiles and clinical outcomes of SSTIs in hematopoietic stem cell transplantation (HSCT) patients remain unclear. This study included 228 patients (3.67%) who developed SSTIs within 180 days after allogeneic HSCT from January 2004 to December 2019 in Peking University People’s Hospital. The overall annual survival rate was 71.5%. We compared the differences between survivors and non-survivors a year after transplant and found that primary platelet graft failure (PPGF), comorbidities of acute kidney injury (AKI), and hospital-acquired pneumonia (HAP) were independent risk factors for death in the study population. A PPGF–AKI–HAP risk stratification system was established with a mortality risk score of 1×PPGF+1×AKI+1×HAP. The areas under the curves of internal and external validation were 0.833 (95% CI 0.760–0.906) and 0.826 (95% CI 0.715–0.937), respectively. The calibration plot revealed the high consistency of the estimated risks, and decision curve analysis showed considerable net benefits for patients.

关键词： skin and soft tissue infections     hematopoietic stem cell transplantation     risk stratification system     mortality    

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Probing the redox process of

Rui Lu, Wei Chen, Wen-Wei Li, Guo-Ping Sheng, Lian-Jun Wang, Han-Qing Yu

《环境科学与工程前沿（英文）》 2017年 第11卷 第1期 doi: 10.1007/s11783-017-0905-y

摘要： Fluorescece spectroelectrochemistry is used to probe redox process of benzoquinone. The benzoquinone reduction state has a lower fluorescence quantum efficiency. CVF and DCVF can reveal more information about benzoquinone redox reactions. This method can analyze compounds with fluorescence and electrochemical activities. Quinones are common organic compounds frequently used as model dissolved organic matters in water, and their redox properties are usually characterized by either electrochemical or spectroscopic methods separately. In this work, electrochemical methodology was combined with two fluorescence spectroelectrochemical techniques, cyclic volta- fluorescence spectrometry (CVF) and derivative cyclic volta- fluorescence spectrometry (DCVF), to determine the electrochemical properties of -benzoquinone in dimethyl sulfoxide, an aprotic solution. The CVF results show that the electrochemical reduction of -benzoquinone resulted in the formation of radical anion and dianion, which exhibited a lower fluorescence intensity and red-shift of the emission spectra compared to that of -benzoquinone. The fluorescence intensity was found to vary along with the electrochemical oxidation and reduction of -benzoquinone. The CVF and DCVF results were in good consistence. Thus, the combined method offers a powerful tool to investigate the electrochemical process of -benzoquinone and other natural organic compounds.

关键词： p-Benzoquinone     Electrochemistry     Fluorescence     Spectroelectrochemistry     Derivative cyclic volta fluorescence    

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Chaotic behavior of LNG after stratification in main stream region of storage tank

WANG Jingjing, MA Xiaoqian

《能源前沿（英文）》 2008年 第2卷 第4期   页码 514-518 doi: 10.1007/s11708-008-0076-4

摘要： A study of the chaotic behavior of liquefied natural gas (LNG) after stratification in the main stream region of a storage tank was conducted. Based on non-linear dynamics, a 2-dimensional Rayleigh-Benard convection model was developed to simulate the convection, Lorenz equations of LNG convection were deduced from conservation equations, and the Runge-Kutta method was used to solve the equations. The results showed that when = 1.33, 106 < < 1470, chaos was obtained, which meant that the velocity field and the temperature field were highly unsteady. In addition, the influence of temperature and scale factor on the solutions and the corresponding range of parameters were studied. The results revealed that the chaos in LNG convection resulted from the interaction of buoyancy and viscid forces. A small quantity of heat impacting the storage tank would lead to a strong and unstable convection of LNG in the main stream region.

关键词： Runge-Kutta     non-linear     corresponding     temperature     addition    

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Persistent free radicals in humin under redox conditions and their impact in transforming polycyclic

Hanzhong Jia, Yafang Shi, Xiaofeng Nie, Song Zhao, Tiecheng Wang, Virender K. Sharma

《环境科学与工程前沿（英文）》 2020年 第14卷 第4期 doi: 10.1007/s11783-020-1252-y

摘要： Abstract • Regulation of redox conditions promotes the generation of free radicals on HM. • HM-PFRs can be fractionated into active and inactive types depending on stability. • The newly produced PFRs readily release electrons to oxygen and generate ROS. • PFR-induced ROS mediate the transformation of organic contaminants adsorbed on HM. The role of humic substance-associated persistent free radicals (PFRs) in the fate of organic contaminants under various redox conditions remains unknown. This study examined the characterization of original metal-free peat humin (HM), and HM treated with varying concentrations of H2O2 and L-ascorbic acid (VC) (assigned as H2O2-HM and VC-HM). The concentration of PFRs in HM increased with the addition of VC/H2O2 at concentrations less than 0.08 M. The evolution of PFRs in HM under different environmental conditions (e.g., oxic/anoxic and humidity) was investigated. Two types of PFRs were detected in HM: a relatively stable radical existed in the original sample, and the other type, which was generated by redox treatments, was relatively unstable. The spin densities of VC/H2O2-HM readily returned to the original value under relatively high humidity and oxic conditions. During this process, the HM-associated “unstable” free radicals released an electron to O2, inducing the formation of reactive oxygen species (ROS, i.e., •OH and •O2−). The generated ROS promoted the degradation of polycyclic aromatic hydrocarbons based on the radical quenching measurements. The transformation rates followed the order naphthalene>phenanthrene>anthracene>benzo[a]pyrene. Our results provide valuable insight into the HM-induced transformation of organic contaminants under natural conditions.

关键词： Humic substance     Polycyclic aromatic hydrocarbons (PAHs)     Persistent free radicals (PFRs)     Redox     Reactive oxygen species (ROS)    

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Pressure drop analysis on the positive half-cell of a cerium redox flow battery using computational fluid

Fernando F. Rivera, Berenice Miranda-Alcántara, Germán Orozco, Carlos Ponce de León, Luis F. Arenas

《化学科学与工程前沿（英文）》 2021年 第15卷 第2期   页码 399-409 doi: 10.1007/s11705-020-1934-9

摘要： Description of electrolyte fluid dynamics in the electrode compartments by mathematical models can be a powerful tool in the development of redox flow batteries (RFBs) and other electrochemical reactors. In order to determine their predictive capability, turbulent Reynolds-averaged Navier-Stokes (RANS) and free flow plus porous media (Brinkman) models were applied to compute local fluid velocities taking place in a rectangular channel electrochemical flow cell used as the positive half-cell of a cerium-based RFB for laboratory studies. Two different platinized titanium electrodes were considered, a plate plus a turbulence promoter and an expanded metal mesh. Calculated pressure drop was validated against experimental data obtained with typical cerium electrolytes. It was found that the pressure drop values were better described by the RANS approach, whereas the validity of Brinkman equations was strongly dependent on porosity and permeability values of the porous media.

关键词： CFD simulation     porous media     porous electrode     pressure drop     redox flow battery    

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Redox flow batteries—Concepts and chemistries for cost-effective energy storage

Matthäa Verena HOLLAND-CUNZ, Faye CORDING, Jochen FRIEDL, Ulrich STIMMING

《能源前沿（英文）》 2018年 第12卷 第2期   页码 198-224 doi: 10.1007/s11708-018-0552-4

摘要： Electrochemical energy storage is one of the few options to store the energy from intermittent renewable energy sources like wind and solar. Redox flow batteries (RFBs) are such an energy storage system, which has favorable features over other battery technologies, e.g. solid state batteries, due to their inherent safety and the independent scaling of energy and power content. However, because of their low energy-density, low power-density, and the cost of components such as redox species and membranes, commercialised RFB systems like the all-vanadium chemistry cannot make full use of the inherent advantages over other systems. In principle, there are three pathways to improve RFBs and to make them viable for large scale application: First, to employ electrolytes with higher energy density. This goal can be achieved by increasing the concentration of redox species, employing redox species that store more than one electron or by increasing the cell voltage. Second, to enhance the power output of the battery cells by using high kinetic redox species, increasing the cell voltage, implementing novel cell designs or membranes with lower resistance. The first two means reduce the electrode surface area needed to supply a certain power output, thereby bringing down costs for expensive components such as membranes. Third, to reduce the costs of single or multiple components such as redox species or membranes. To achieve these objectives it is necessary to develop new battery chemistries and cell configurations. In this review, a comparison of promising cell chemistries is focused on, be they all-liquid, slurries or hybrids combining liquid, gas and solid phases. The aim is to elucidate which redox-system is most favorable in terms of energy-density, power-density and capital cost. Besides, the choice of solvent and the selection of an inorganic or organic redox couples with the entailing consequences are discussed.

关键词： electrochemical energy storage     redox flow battery     vanadium    

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Iron oxidation-reduction and its impacts on cadmium bioavailability in paddy soils: a review

Chunhua ZHANG, Ying GE, Huan YAO, Xiao CHEN, Minkun HU

《环境科学与工程前沿（英文）》 2012年 第6卷 第4期   页码 509-517 doi: 10.1007/s11783-012-0394-y

摘要： Redox conditions in paddy soils may vary as they are submerged and drained during rice growth. This change may bring about reductive dissolution of iron (Fe) oxides and subsequent formation of secondary Fe-bearing minerals in rice paddies. The mobility and bioavailability of metal contaminants such as cadmium (Cd) in paddy soils are closely related to the chemical behaviors of Fe. Therefore, in this paper, advances in the study of paddy Fe redox transformations and their effects on Cd availability to rice are briefly reviewed. Current concepts presented in this review include the forms of Fe in paddy soils, the reactions involved in Fe oxidation-reduction, chemical factors affecting Fe redox processes, Cd availability to rice and the impacts of Fe transformation on Cd uptake and translocation in rice. Prospects for future research in this area are also discussed.

关键词： paddy soil     redox     iron     cadmium     bioavailability     rice    

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Structure creation in earthen construction materials: information from dry soil mixtures

Christopher BECKETT, Charles AUGARDE

《结构与土木工程前沿（英文）》 2011年 第5卷 第2期   页码 151-159 doi: 10.1007/s11709-011-0109-7

摘要： There is increasing interest in the use of earthen construction materials, such as rammed earth, due to their inherent sustainability. These materials have been used by man for thousands of years and some of the earliest examples can be found in China. Features of the structures of these materials arise from the means of production. In particular, in situ earthen construction materials exhibit strong anisotropy due to their layered nature. A more subtle structure effect arises from the way that the earth mixture is deposited. This paper reviews and discusses stratification effects in dry soil mixtures, including some original experimental work, and indicates some links between the features of the dry mixtures and earthen construction materials. Improved understanding of the physical processes in play will allow more accurate specification of these materials in the future, and hence spread their use.

关键词： rammed earth     stratification     particle size distribution     pore size distribution    

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Numerical simulation of charge stratifications to improve combustion and NO formation of lean-burn SI engines

Zhijun PENG ,

《能源前沿（英文）》 2009年 第3卷 第3期   页码 353-358 doi: 10.1007/s11708-009-0035-8

摘要： The influences of charge stratification on spark ignition (SI) engine combustion and NO emission were analyzed using a phenomenological model. The mixture in the cylinder was divided spherically into three parts: a central core with a stoichiometric air-fuel charge, a dilution region without any combustible charge, and a mixing region lying between the core and the dilution region. Three mixture stratification parameters such as the extent of dilution in the mixing region, the extent of combustible charge in the mixing region, and the gradient of stratification in the mixing region were investigated. The results indicate that the extent of combustible charge in the mixing region could reduce in-cylinder NO formation significantly, compared with the extent of dilution in the mixing region. As long as the degree of dilution in the mixing region is within the dilution limit of the combustible charge, the gradient of dilution has little effect on combustion and NO formation.

关键词： charge stratification     SI engine     lean-burn combustion     NO emission    

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标题 作者 时间 类型 操作

Nitrifying population dynamics in a redox stratified membrane biofilm reactor (RSMBR) for treating ammonium-rich

Rongchang WANG, Xinmin ZHAN, Yalei ZHANG, Jianfu ZHAO

期刊论文

A methodology for regulating fuel stratification and improving fuel economy of GCI mode via double main-injection

期刊论文

Comparison of prechilling stratification and sulfuric acid scarification on seed germination of

Nan WANG, Jing GAO, Suiqi ZHANG, Feng YAN

期刊论文

Photoreduction adjusted surface oxygen vacancy of BiMoO for boosting photocatalytic redox performance

期刊论文

High butanol production by regulating carbon, redox and energy in Clostridia? ?

Jianfa Ou,Chao Ma,Ningning Xu,Yinming Du,Xiaoguang (Margaret) Liu

期刊论文

Characterization and comparison of organic functional groups effects on electrolyte performance for vanadium redox

期刊论文

Risk stratification system for skin and soft tissue infections after allogeneic hematopoietic stem cell

期刊论文

Probing the redox process of

Rui Lu, Wei Chen, Wen-Wei Li, Guo-Ping Sheng, Lian-Jun Wang, Han-Qing Yu

期刊论文

Chaotic behavior of LNG after stratification in main stream region of storage tank

WANG Jingjing, MA Xiaoqian

期刊论文

Persistent free radicals in humin under redox conditions and their impact in transforming polycyclic

Hanzhong Jia, Yafang Shi, Xiaofeng Nie, Song Zhao, Tiecheng Wang, Virender K. Sharma

期刊论文

Pressure drop analysis on the positive half-cell of a cerium redox flow battery using computational fluid

Fernando F. Rivera, Berenice Miranda-Alcántara, Germán Orozco, Carlos Ponce de León, Luis F. Arenas

期刊论文

Redox flow batteries—Concepts and chemistries for cost-effective energy storage

Matthäa Verena HOLLAND-CUNZ, Faye CORDING, Jochen FRIEDL, Ulrich STIMMING

期刊论文

Iron oxidation-reduction and its impacts on cadmium bioavailability in paddy soils: a review

Chunhua ZHANG, Ying GE, Huan YAO, Xiao CHEN, Minkun HU

期刊论文

Structure creation in earthen construction materials: information from dry soil mixtures

Christopher BECKETT, Charles AUGARDE

期刊论文

Numerical simulation of charge stratifications to improve combustion and NO formation of lean-burn SI engines

Zhijun PENG ,

期刊论文