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Magnetotactic bacteria:Characteristics and environmental applications

Frontiers of Environmental Science & Engineering 2020年第4期14卷 3-16,F0004页

作者： Xinjie Wang Yang Li Jian Zhao Hong Yao Siqi Chu Zimu Song Zongxian He Wen Zhang State Key Laboratory of Water Environment Simulation School of EnvironmentBeijing Normal UniversityBeijing 100875China John A.Reif Jr.Department of Civil and Environmental EngineeringNew Jersey Institute of TechnologyNewarkNJ 07102USA Beijing Key Laboratory of Aqueous Typical Pollutants Control and Water Quality Safeguard Beijing International Cooperation Base for Science and Technology on Antibiotics/Resistance Genes Water Environmental Pollution Control TechnologySchool of Civil EngineeringBeijing Jiaotong UniversityBeijing 100044China

Magnetotactic bacteria(MTB)are a group of Gram-negative prokaryotes that respond to the geomagnetic *** unique property is attributed to the intracellular magnetosomes,which contains membrane-bound nanocrystals of magnetic iron *** review summarizes the most recent advances in MTB,magnetosomes,and their potential applications especially the environmental pollutant control or *** morphologic and phylogenetic diversity of MTB were first introduced,followed by a critical review of isolation and cultivation *** have devoted to optimize the factors,such as oxygen,carbon source,nitrogen source,nutrient broth,iron source,and mineral elements for the growth of *** the applications of MTB in modem biological and medical fields,little attention was made on the environmental applications of MTB for wastewater treatment,which has been summarized in this *** example,applications of MTB as adsorbents have resulted in a novel magnetic separation technology for removal of heavy metals or organic pollutants in *** addition,we summarized the current advance on pathogen removal and detection of endocrine disruptor which can inspire new insights toward sustainable engineering and ***,the new perspectives and possible directions for future studies are recommended,such as isolation of *** modification of MTB for mass production and new environmental *** ultimate objective of this review is to promote the applications of MTB and magnetosomes in the environmental fields.

关键词： Magnetotactic bacteria Magnetosome Heavy metal radionuclide Organic pollutants

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Investigation of combined degrader for proton facility based on BDSIM/FLUKA Monte Carlo methods

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Nuclear Science and Techniques 2022年第2期33卷 30-39页

作者： Man-Fen Han Jin-Xing Zheng Xian-Hu Zeng Jun-Song Shen Hefei Institutes of Physical Science Chinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China

The significant advantage of proton therapy over other particle-based techniques is in the unique physical characteristics of the Bragg *** can achieve a highly conformal dose distribution and maximize the probability of tumor control by varying the irradiation *** proton facilities use cyclotrons for fixed energy beam extraction and are equipped with degrader and collimator systems for energy modulation and emittance ***,interactions between charged particles and degrader materials inevitably cause beam loss and divergence and deteriorate beam performance,which present great challenges for downstream transport and clinical *** this work,we investigate a method of energy reduction by combining boron carbide and graphite in a degrader to obtain greater beam transmission at lower *** results demonstrate that the beam size and emittance at the exit of the combined degrader diverge less than those of multi-wedge one in the energy range of 70-160 ***,the transmission efficiency after the first dipole also shows improvements of 36.26%at 70 MeV and 70.55%at 110 *** a component with a high activity level,the degrader causes additional ambient radiation during *** induced radiation even remains several hours after system *** of material activation and induced radiation based on 1 h irradiation with a 400 nA beam current shows that the combined degrader has a definite advantage in shielding despite producing more secondary *** radioactivity and average ambient dose equivalent are reduced by 50%compared with the multiwedge degrader at the important cooling time of 1 *** 12 h and 24 h of cooling,the radiation levels of degraders decrease slightly due to the presence of long half-life residual *** average dose generated from the multi-wedge degrader is still 1.25 times higher than that of the combined one.

关键词： Proton therapy Degrader Boron carbide Transmission efficiency radionuclide Ambient dose equivalent

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MXene-based nanomaterials as adsorbents for wastewater treatment:a review on recent trends

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Frontiers of Materials Science 2022年第1期16卷 55-70页

作者： Rajesh K.JENA Himadri Tanaya DAS Braja N.PATRA Nigamananda DAS Centre of Excellence in Advanced Materials and Applications Utkal UniversityVani ViharBhubaneswar 751004India Department of Chemistry Utkal UniversityVani ViharBhubaneswar 751004India

The wastewater treatment is a challenging research area to reduce the increasing pressure on limited fresh water *** several techniques adopted and practiced,adsorption is one of the most effective and sustainable ecofriendly *** recent years,MXene nanomaterials,a new family of transition metal carbides,have gained increasing attention as the potential adsorbent for pollutants due to their unique features such as large surface area with abundant active sites and hydrophilicity.A wide range of pollutants *** metal ions,organic dyes,radionuclides,and toxic gas molecules have been sensed by 2D *** inclusive understanding on the adsorptive behavior of MXene-based materials is needed to explain the removal mechanism and effects of different adsorption *** review gives a general overview on recent research progress on MXene materials with special reference to their applications for the adsorptive removal of different *** general trends in the synthesis of MXenes,their stability and different factors affecting the adsorption process along with the main challenges in understanding the full potential of MXenes for environmental applications are discussed.

关键词： MXene adsorption wastewater treatment heavy metal radionuclide

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Sedimentary record of climate change in a high latitude fjord—Kongsfjord

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Acta Oceanologica Sinica 2023年第1期42卷 91-102页

作者： Hang Wu Binbin Deng Jinlong Wang Sheng Zeng Juan Du Peng Yu Qianqian Bi Jinzhou Du State Key Laboratory of Estuarine and Coastal Research East China Normal UniversityShanghai200241China Monitoring Center of Aquatic Environment of Pearl River Basin Guangzhou510611China Research Centre for Eco-Environmental Engineering Dongguan University of TechnologyDongguan523808China Big Data Institute of Digital Natural Disaster Monitoring in Fujian Xiamen University of TechnologyXiamen361024China

The sedimentary record of climate change in the Arctic region is useful for understanding global *** is located in the subpolar region of the Arctic and is a suitable site for studying climate *** retreat is occurring in this region due to climate change,leading to an increase in meltwater outflow with a high debris *** August 2017,we collected a sediment Core Z3 from the central fjord near the Yellow River ***,we used the widely used chronology method of 210Pb,^(137)Cs,and other parameters to reflect the climate change record in the sedimentary environment of *** results showed that after the mid-late 1990s,the mass accumulation rate of this core increased from 0.10 g/(cm^(2)·a)to 0.34 g/(cm^(2)·a),while the flux of^(210)Pb_(ex)increased from 125 Bq/(m^(2)·a)to 316 Bq/(m^(2)·a).The higher sedimentary inventory of^(210)Pb_(ex)in Kongsfjord compared to global fallout might have been caused by sediment focusing,boundary scavenging,and riverine *** between the inventory of^(137)Cs and global fallout indicated that terrestrial particulate matter was the main source of^(137)Cs in fjord *** sedimentation rate increased after 1997,possibly due to the increased influx of glacial meltwater containing *** addition,the^(137)Cs activity,percentage of organic carbon(OC),and OC/total nitrogen concentration ratio showed increasing trends toward the top of the core since 1997,corresponding to a decrease in the mass balance of glaciers in the *** results ofδ^(13)C,δ^(15)N and OC/TN concentration ratio showed both terrestrial and marine sources contributed to the organic matter in Core *** relative contribution of terrestrial organic matter which was calculated by a two-endmember model showed an increased trend since *** these data indicate that global climate change has a significant impact on Arctic glaciers.

关键词： Kongsfjord radionuclide organic carbon/total nitrogen(OC/TN)concentration ratio δ^(13)C δ^(15)N sediment record climate change

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Distribution of 137Cs and 60Co in plough layer of farmland: Evidenced from a lysimeter experiment using undisturbed soil columns

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Pedosphere 2021年第1期31卷 180-190页

作者： Wenxiang LIU Yong LI Hanqing YU Surinder SAGGAR Daozhi GONGI Qiong ZHANG lstiute of En/noumewr and Sutainable Doelopmen in Apriculure Chinese Academy of Agrcdtwrad Scences.Bejing 00081Chinma Guangd Uniwenin Naneing 530005China Maraak Whenan-Landcare Researh Priare Bog 11052Palmerston North 442New Zealand Minclear aud Radiaton Safr Cemer Minisry of Eviromensal Proecrion时ChinaBeijing 00002China

radionuclide fallout during nuclear accidents on the land may impair the atmosphere, contaminate farmland soils and crops, and can even reach the groundwater. Previous research focused on the field distribution of deposited radionuclides in farmland soils, but details of the amounts of radionuclides in the plough layer and the changes in their proportional distribution in the soil profile with time are still inadequate. In this study, a lysimeter experiment was conducted to determine the vertical migration of 137Cs and 60Co in brown and aeolian sandy soils, collected from the farmlands adjoining Shidaowan Nuclear Power Plant(NPP) in eastern China, and to identify the factors influencing their migration depths in soil. At the end of the experiment(800 d), >96% of added 137Cs and 60Co were retained in the top 0–20 cm soil layer of both soils;very little 137Cs or 60Co initially migrated to 20–30 cm, but their amounts at this depth increased with time. The migration depth of 137Cs was greater in the aeolian sandy soil than in the brown soil during 0–577 d, but at the end of the experiment, 137Cs migrated to the same depth(25 cm) in both soils. Three phases on the vertical migration rate(v) of 60Co in the aeolian sandy soil can be identified: an initial rapid movement(0–355 d, v = 219 ± 17 mm year-1), followed by a steady movement(355–577 d, v = 150 ± 24 mm year-1) and a very slow movement(577–800 d, v = 107 ± 7 mm year-1). In contrast, its migration rate in the brown soil(v = 133 ± 17 mm year-1) was steady throughout the 800-d experimental period. The migration of both 137Cs and 60Co in the two soils appears to be regulated by soil clay and silt fractions that provide most of the soil surface area, soil organic carbon(SOC), and soil pH, which were manifested by the solid-liquid distribution coefficient of 137Cs and 60Co. The results of this study suggest that most 137Cs and 60Co remained within the top layer(0–20 cm depth) of farmland soils following a simulated NPP acc

关键词： aeolian sandy soil brown soil deposited radionuclide migration depth radionuclide vertical migration rate

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Short-and long-term sediment transport in western Bohai Bay and coastal areas

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Chinese Journal of Oceanology and Limnology 2010年第3期28卷 583-592页

作者：冯桓张卫国贾丽 Michael P.WEINSTEIN 张秋丰袁德奎陶建华俞立中 Department of Earth and Environmental Studies Montclair State University State Key Laboratory of Estuarine and Coastal Research East China Normal University Institute for Sustainability Studies Montclair State University Marine Environmental Monitoring and Forecasting Center Department of Mechanics Tianjin University

Sediment cores （-40-100 cm） were collected at 12 locations in the western Bohai Bay, the Haihe River estuary, the Yongding River estuary and the Tianjin Harbor, China, during 24-26 July 2007, and analyzed for ^7Be and ^210pb activities. Due to localized hydrodynamic patterns and frequent disturbance from dredging activities, steady-state sedimentation features were not observed in this study. As demonstrated in the VBe and ^210pb profiles, the temporal and spatial variations of these radionuclides support a non-steady state depositional environment in the study area. By comparing ^7Be and ^210pb inventories in the sediments with those of the atmospheric source, we found that： 1） sediments dredged from the Tianjin Harbor or eroded from nearby estuarine and coastal areas are retained in the western Bohai Bay for relatively short intervals （several months）, as reflected in the relatively high ^7Be inventories in the western Bohai Bay; 2） over the long-term （years to decades）, ^210Pb inventories in the sediments imply that there is a net on-shore transport of sediments, and the sediments are mass-balanced in the entire study area. Overall, our results suggest that the sediments are retained in the estuaries and the western Bohai Bay despite local variability in sediment dynamics and disturbance due to human activities.

关键词： Bohai Bay estuary sedimentation sediment transport radionuclide

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Reductive immobilization and long-term remobilization of radioactive pertechnetate using bio-macromolecules stabilized zero valent iron nanoparticles

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Chinese Chemical Letters 2019年第12期30卷 2163-2168页

作者： Haodong Ji Yangmo Zhu Jun Duan Wen Liu Dongye Zhao The Key Laboratory of Water and Sediment Science Ministry of EducationCollege of Environment Science and EngineeringPeking UniversityBeijing 100871China Environmental Engineering Program Department of Civil EngineeringAuburn UniversityAuburnAL 36849United States The Beijing Innovation Center for Engineering Science and Advanced Technology(BIC-ESAT) Peking UniversityBeijing 100871China Institute of Environmental Science Taiyuan University of Science and TechnologyTaiyuan 030024China

Reductive immobilization of radioactive pertechnetate(99TcO4^-) in simulated groundwater was studied by prepared carboxymethyl cellulose(CMC) and starch stabilized zero valent iron nanoparticles(nZVI),and long-term remobilization of reduced Tc was also evaluated under anoxic and oxic *** stabilized nZVI can effectively reduce soluble 99Tc(Ⅶ) to insoluble 99 Tc(Ⅳ),and they can be easily delivered into a contaminated groundwater zone and facilitate in situ *** this study,CMCstabilized nZVI showed higher reactivity than that using starch as the *** experiments indicated that more than 99% of 99 Tc(Ⅶ)(CO=12 mg/mL) was reduced and removed from groundwater by CMC-stabilized nZVI with a CMC content of 0.2%(w/w) at a broad pH of 5-8.X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS) analyses further confirmed that 99Tc(Ⅶ)O4^-transformed into 99Tc(Ⅳ)O2(s).The presence of bicarbonate exhibited insignificant effect on Tc immobilization,while humic acid(HA) inhibited reaction mainly due to retardation on electron transfer and formation of Tc(IV)-HA *** interesting,the immobilized Tc(Ⅳ) remained insoluble even after 120 d under anoxic condition,while only^21 % was remobilized when exposed to ***,biomacromolecules stabilized nZVI nanoparticles could be a viable alternative for in situ remediation of radioactive contamination in groundwater.

关键词： Reductive immobilization radionuclide Stabilized nanoparticles Zero valent iron Groundwater Technetium

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Spectrometry analysis based on approximation coefficients and deep belief networks

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Nuclear Science and Techniques 2018年第5期29卷 65-74页

作者： Jian-Ping He Xiao-Bin Tang Pin Gong Peng Wang Zhen-Yang Han Wen Yan Le Gao Department of Nuclear Science and Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Jiangsu Key Laboratory of Nuclear Energy Equipment Materials Engineering Nanjing 210016China

A method of spectrometry analysis based on approximation coefficients and deep belief networks was developed. Detection rate and accurate radionuclide identification distance were used to evaluate the performance of the proposed method in identifying radionuclides. Experimental results show that identification performance was not affected by detection time, number of radionuclides, or detection distance when the minimum detectable activity of a single radionuclide was satisfied. Moreover, the proposed method could accurately predict isotopic compositions from the spectra of moving radionuclides. Thus, the designed method can be used for radiation monitoring instruments that identify radionuclides.

关键词： Approximation coefficient Deep belief network Spectrometry analysis radionuclide identification Detection rate

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Activated Sericite:An Efficient and Effective Natural Clay Material for Attenuation of Cesium from Aquatic Environment

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Pedosphere 2014年第6期24卷 731-742页

作者： D.TIWARI LALHMUNSIAMA S.I.CHOI S.M.LEE Department of Chemistry School of Physical SciencesMizoram University Department of Health and Environment Kwandong University Department of Environmental Engineering Kwangwoon University

Sericite is mica-based natural clay that is annealed at 800 ℃ for 4 h, followed by acid activation using 3.0 mol L-1HCl at 100℃. The interaction of cesium(I), Cs(I), with sericite could provide useful data for the study of soil erosion or mass water movement utilizing the natural radioactive Cs. In this study sericite and activated sericite were used to assess their suitability in the attenuation of Cs from the aquatic environment under both batch and column experiments. The surface morphological studies indicated that a disordered and heterogeneous surface structure was exhibited by the activated sericite, whereas the native sericite exhibited a compact and layered structure. The Brunauer-Emmett-Teller(BET) specific surface area results indicated a significant increase in the surface area due to the activation of sericite. The batch reactor data collected for various parametric studies revealed that an increase in p H(from 2.0 to 8.0) and sorbate concentration(from 10.0 to 100.0 mg L-1) apparently favored the attenuation of Cs(I). The timedependent sorption data revealed that Cs(I) uptake was very rapid, and it achieved its saturation value within just 50 min of *** kinetic modeling studies indicated that the uptake of Cs(I) followed a pseudo-second-order rate equation; hence, the attenuation capacity of these solids for Cs(I) was estimated to be 0.858 and 4.353 mg g-1for sericite and activated sericite solids, *** adsorption isotherm modeling data showed a reasonably good applicability of the Freundlich model than the Langmuir *** effect of background electrolyte concentrations(0.001 to 0.1 mol L-1) of Mg(NO3)2indicated that the presence of this electrolyte could not significantly affect the percent removal of Cs(I) by activated sericite. Furthermore, the fixed-bed column reactor operations were performed to obtain the breakthrough data, which were fitted well to the Thomas non-linear equation. Therefore, the loading capacity of Cs(I) wa

关键词： adsorption isotherms breakthrough data electrolyte kinetics radionuclide

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Impacts of oak deforestation and rainfed cultivation on soil redistribution processes across hillslopes using ^(137)Cs techniques

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Forest Ecosystems 2021年第3期8卷 425-438页

作者： Shamsollah Ayoubi Nafiseh Sadeghi Farideh Abbaszadeh Afshar Mohammad Reza Abdi Mojtaba Zeraatpisheh Jesus Rodrigo-Comino Department of Soil Science College of AgricultureIsfahan University of TechnologyIsfahan 84156-83111Iran Department of Soil Science College of AgricultureUniversity of JiroftKermanIran Department of Physics Faculty of ScienceUniversity of IsfahanIsfahan 81747-73441Iran Henan Key Laboratory of Earth System Observation and Modeling Henan UniversityKaifeng 475004China College of Environment and Planning Henan UniversityKaifeng 475004China Department of Physical Geography University of TrierTrierGermany Soil Erosion and Degradation Research Group Department of GeographyUniversitat de ValènciaValenciaSpain

Background:As one of the main components of land-use change,deforestation is considered the greatest threat to global environmental diversity with possible irreversible environmental ***,one example could be the impacts of land-use changes from oak forests into agricultural ecosystems,which may have detrimental impacts on soil mobilization across ***,to date,scarce studies are assessing these impacts at different slope positions and soil depths,shedding light on key geomorphological ***:In this research,the Caesium-137(^(137)Cs)technique was applied to evaluate soil redistribution and soil erosion rates due to the effects of these above-mentioned land-use *** achieve this goal,we select a representative area in the Lordegan district,central Iran.^(137)Cs depth distribution profiles were established in four different hillslope positions after converting natural oak forests to rainfed *** each hillslope,soil samples from three depths(0–10,10–20,and 20–50 cm)and in four different slope positions(summit,shoulder,backslope,and footslope)were taken in three transects of about 20m away from each *** activity of ^(137)Cs was determined in all the soil samples(72 soil samples)by a gamma *** addition,some physicochemical properties and the magnetic susceptibility(MS)of soil samples were ***:Erosion rates reached 51.1 t·ha^(−1)·yr^(−1) in rainfed farming,whereas in the natural forest,the erosion rate was 9.3 t·ha^(−1)·yr^(−1).Magnetic susceptibility was considerably lower in the cultivated land(χhf=43.5×10^(−8)m^(3)·kg^(−1))than in the natural forest(χhf=55.1×10^(−8)m^(3)·kg^(−1)).The lower soil erosion rate in the natural forest land indicated significantly higher MS in all landform positions except at the summit one,compared to that in the rainfed farming *** shoulder and summit positions were the most erodible hillslope positions in the natural forest and rainfed farming,res

关键词： Land-use change Soil redistribution Topographical changes radionuclide Rainfed farming Deforestation

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