检索结果-南通市图书馆

西南典型碳酸盐岩高地质背景区农田重金属化学形态、影响因素及回归模型

在线全文

学校读者我要写书评

暂无评论

环境科学 2024年第5期45卷 2995-3004页

作者：唐瑞玲徐进力刘彬杜雪苗顾雪于林松毕婧中国地质科学院地球物理地球化学勘查研究所廊坊065000 山东省物化探勘查院济南250013 山东省地质测绘院济南250014

土壤重金属化学形态是决定重金属生物活性和生物毒性的重要因素,是科学评价西南碳酸盐岩高地质背景区土壤重金属生态风险的关键.为了探明碳酸盐岩高地质背景区土壤重金属化学形态分布情况,选择贵州省典型碳酸盐岩分布区,以第二次全国土... 详细信息

土壤重金属化学形态是决定重金属生物活性和生物毒性的重要因素,是科学评价西南碳酸盐岩高地质背景区土壤重金属生态风险的关键.为了探明碳酸盐岩高地质背景区土壤重金属化学形态分布情况,选择贵州省典型碳酸盐岩分布区,以第二次全国土壤普查图斑为采样单元,在农田中采集土壤表层样品309件,利用改进的Tessier七步顺序提取法,分析了As、Cd、Cu、Hg、Ni、Pb和Zn等7种重金属的水溶态(F1)、离子交换态(F2)、碳酸盐结合态(F3)、弱有机结合态(F4)、铁锰氧化物结合态(F5)、强有机结合态(F6)和残渣态(F7)这7种化学形态.结果发现,土壤中重金属As、Cu、Hg、Ni、Pb和Zn残渣态比例均超过50%,有效组分(F1~F3)比例均小于5%,潜在生物有效组分(F4~F6)比例低于45%,活性较低,生态风险不高.Cd的有效组分和潜在生物有效组分占比分别为55.49%和29.37%,远高于其他重金属,基于土壤重金属形态的生态风险远小于基于土壤总量的生态风险.逐步回归方程可以有效建立Cd、Cu和Pb生物有效组分与影响因素之间的关系.重金属全量和pH值是影响碳酸盐岩高地质背景区土壤重金属化学形态的重要因子,受研究区长期土法炼锌活动和碳酸盐岩风化成土过程中重金属元素倾向于在残渣态中富集的影响,土壤有机质(OM)和氧化物含量对土壤重金属化学形态影响相对较小.

关键词：土壤重金属化学形态生态评价影响因素回归模型高地质背景区

Effect of hydrogen on the friction and wear of Ni-P coatings

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2010年第2期17卷 241-245页

作者： Qing-jun Zhou jin-xu li Wu-yang Chu Corrosion and Protection Center Key Lab of Environmental Cracking Ministry of Education of China University of Science and Technology Beijing Beijing 100083 China R ＆ D Center Baoshan Iron ＆ Steel Co. Ltd. Shanghai 201900 China

The effects of charging and outgassing on the friction and wear of Ni-P amorphous and nanocrystalline coatings were studied under ambient humidity and *** results indicate that hydrogen charging can greatly decrease the volume loss during friction and increase the wear ***,the wear durability can be restored after *** are many cracks on the brittle nanocrystalline before charging,and no crack appears after charging,but there are only a few cracks on the outgassed *** indicates that hydrogen charging can inhibit the crack formation during friction for the brittle Ni-P *** the charged sample,after the surface layer was removed by polishing,the wear track and the friction coefficient are consistent with those of an uncharged *** friction coefficient of the charged amorphous coating is very small within the first 140 s and then increases suddenly to the value corresponding to the uncharged *** absorbed surface layer lubricates the surface,reduces the friction coefficient,and improves the wear durability.

关键词： friction wear hydrogen Ni-P coating nanocrystalline

Formation of Na_(1+x)V_3O_8 Nanoribbon Thin Film from V_2O_5 Xerogel on Sodium Silicate Glass Substrate

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2007年第4期23卷 381-383页

作者： GUO Yi xu jin-jie li Jun YANG Wen-sheng College of Chemistry Jilin University Changchun 130012 P. R. China

Na1＋xV3O8 nanoribbon thin film was successfully fabricated by annealing the V2O5 xerogel film on sodium sili-cate glass substrate at 450℃. It has been identified that the amount of sodium ions diffused into the V2O5 xerogel film increases with the high temperature of annealing treatment. The sodium glass substrate serves as a limited sodium source to induce the transformation from V2O5 to Na1＋xV3O8.

关键词： Vanadium pentoxide Sodium silicate glass Nanoribbon Cathode materials

Relationship between Hydrogen Diffusion and Blistering Nucleation and Growth

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2016年第11期23卷 1188-1194页

作者： jin-xu li Hang YIN Xi-na YANG Qian li Ping ZHANG Chun-qian XIE Yan-jing SU li-jie QIAO Corrosion and Protection Center Environment Sensitive Fracture Laboratory(MOE)University of Science and Technology Beijing

The formation condition of hydrogen blister in 18Ni maraging steel without any inner or external stress was investigated. The results show that the critical diffusible hydrogen concentration of a blister forming is about 1.4×10^-5 , which is corresponding to the current density of 30 mA/cm^2 during cathodic charging in a sodium hydroxide solution. For a 0.1 cm thick sample, no matter the current density is equal to or much larger than the critical value, it spends at least about 132 h to form a hydrogen blister when hydrogen charging in single direction. It is approxi- mately equal to the time for hydrogen atom to diffuse throughout the sample, which exactly depends on the hydrogen diffusion coefficient and the penetration depth. The very first clear suggestion was reported that the incubation period for hydrogen blister nucleation was necessary. According to the Fick＇s laws, calculations show that the normalized hydrogen concentration in the escaping surface almost reaches 0.96 times of the charging surface, which means that the diffusion almost reaches a dynamic balance. A model was illustrated to describe the competitive relationship between hydrogen diffusion and blister formation.

关键词： hydrogen blister trap maraging steel hydrogen diffusion incubation time

Causal temporal graph attention network for fault diagnosis of chemical processes

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2024年第6期70卷 20-32页

作者： Jiaojiao Luo Zhehao jin Heping jin Qian li xu Ji Yiyang Dai School of Chemical Engineering Sichuan UniversityChengdu 610065China China Three Gorges Corporation Beijing 100038China

Fault detection and diagnosis(FDD)plays a significant role in ensuring the safety and stability of chemical *** the development of artificial intelligence(AI)and big data technologies,data-driven approaches with excellent performance are widely used for FDD in chemical ***,improved predictive accuracy has often been achieved through increased model complexity,which turns models into black-box methods and causes uncertainty regarding their *** this study,a causal temporal graph attention network(CTGAN)is proposed for fault diagnosis of chemical processes.A chemical causal graph is built by causal inference to represent the propagation path of *** attention mechanism and chemical causal graph were combined to help us notice the key variables relating to fault *** in the Tennessee Eastman(TE)process and the green ammonia(GA)process showed that CTGAN achieved high performance and good explainability.

关键词： Chemical processes Safety Fault diagnosis Causal discovery Attention mechanism Explainability

Relationship between Carotid Atherosclerosis and Cerebral Infarction

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Sciences Journal 2010年第1期25卷 32-37页

作者： Guang-wen li Guan-yi Zheng jin-guo li xu-dong Sun Department of Geriatrics Union Hospital Fujian Medical University Fuzhou 350001 China

Objective To study the relationship between carotid atherosclerosis and cerebral infarction (CI). Methods Between November 2008 and March 2009,147 CI patients (CI group) and 48 patients with non-cerebrovascular diseases (control group) were enrolled from inpatients of Neurology Department of our hospital. The diagnostic criterion of thickened carotid intima was set as 1.0 mm≤intima-media thickness (IMT) 0.05). Conclusions Carotid atherosclerosis is to some extent able to reveal the atherosclerotic condition of cerebral arteries and act as an important predictor for the risk of CI. T

关键词： carotid atherosclerosis cerebral infarction intima-media thickness color Doppler ultrasonography

Enhanced photocatalytic hydrogen production from Co-MOF/CN by nitrogen and sulfur co-doped coal-based carbon quantum dots

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2024年第5期42卷 838-850,I0002页

作者： Shiyong xu Mei li Yijun Wang Caiyun Gao Rongsheng xu Zhiliang jin School of Chemistry and Chemical Engineering North Minzu UniversityYinchuan750021China Ningxia Key Laboratory of Solar Chemical Conversion Technology.North Minzu University.Yinchuan 750021China State Key Laboratory of National Ethnic Affairs Commission Chemical Technology.North Minzu University Yinchuan750021China

A novel composite photocatalyst for photocatalytic decomposition of water for hydrogen evolution was successfully synthesized by in-situ growth of nitrogen and sulfur co-doped coal-based carbon quantum dots(NSCQDs)nanoparticles on the surface of sheet cobalt-based metal-organic framework(Co-MOF)and graphitic carbon nitride(g-C_(3)N_(4),CN).The structure and properties of the obtained catalysts were systematically *** effectively broaden the absorption of Co-MOF and CN in the visible *** new composite photocatalyst has high hydrogen production activity and the hydrogen production rate reaches 6254μmol/(g·h)at pH=*** the same time,NSCQDs synergy Co-MOF/CN composites have good *** four cycles of hydrogen production,the performance remains relatively *** tran sient photocurrent response and Nyquist plot experimental results further demonstrate the improvement of carrier separation efficiency in composite *** semiconductor type(n-type semico nductor)of the single-phase catalyst was determined by the Mott-Schottky test,and the band structure was *** conductive and valence bands of CN are-0.99 and 1.72 eV,respectively,and the conduction and valence bands of Co-MOF are-1.85 and 1.33 eV,*** e mechanism of the photocatalytic reaction can be inferred,that is,Z-type heterojunction is formed between CN an d Co-MOF,and NSCQDs was used as cocatalyst.

关键词： Nitrogen and sulfur co-doped Coal-based carbon quantum dots Co-MOF CN Photocatalytic hydrogen evolution Rare earths

Influence of crystal-transforming agent on the performance and mechanism ofα-high-strength gypsum prepared from FGD gypsum

在线全文

学校读者我要写书评

暂无评论

Particuology 2024年第4期87卷 37-45页

作者： Zhuoyue xu Xiao Wang Biao jin Dawang Zhang Hui li College of Materials Science and Engineering Xi'an University of Architecture and TechnologyXi'an710055China Schoolof Materials and Chemical Engineering Henan University of Urban ConstructionPingdingshan46736China

This paper investigates the impact of flue gas desulfurization(FGD)gypsum's crystal modifier on the characteristics and microcosmic mechanism ofα-high strength *** results demonstrate that all three crystal modifiers can convert FGD gypsum toα-high-strength *** acid(CA)has the most significant influence onα-high-strength gypsum,and the preparedα-high-strength gypsum is short columnar,with an aspect ratio in the range of 1-3,and has a faster setting time,a larger specific surface area,and a smaller standard consistency,higher compressive strength,greater surface hardness,and smaller crystal particle *** initial setting time of theα-high-strength gypsum manufactured with CA crystal modifier was decreased by 36%compared to the blank sample,the final setting time was lowered by 37.5%,and the water consumption of the standard consistency was reduced by 8%.The maximum strength is 32 MPa after 2 h,the absolute dry compressive strength is up to 38 MPa,and the surface hardness is improved by 24.43%.

关键词： Flue gas desulfurization gypsum Crystal modifier Microscopic mechanism α-high-strength gypsum

Laser-Constructing 3D Copper Current Collector with Crystalline Orientation Selectivity for Stable lithium Metal Batteries

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Energy & Environmental Materials 2024年第6期7卷 129-139页

作者： Hui li Gang Wang jin Hu Jun li Jiaxu Huang Shaolin xu Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518000China

The practical application of lithium(li)metal anodes in high-capacity batteries is impeded by the formation of hazardous li *** address this challenge,this research presents a novel methodology that combines laser ablation and heat treatment to precisely induce controlled grain growth within laser-structured grooves on copper(Cu)current ***,this approach enhances the prevalence of Cu(100)facets within the grooves,effectively lowering the overpotential for li nucleation and promoting preferential li *** approaches that modify the entire surface of collectors,our work focuses on selectively enhancing lithiophilicity within the grooves to mitigate the formation of li dendrites and exhibit exceptional performance *** half-cell with these collectors maintains a remarkable Coulombic efficiency of 97.42%over 350 cycles at 1 mA cm^(−2).The symmetric cell can cycle stably for 1600 h at 0.5 mA cm^(−2).Furthermore,when integrated with liFePO4 cathodes,the full-cell configuration demonstrates outstanding capacity retention of 92.39%after 400 cycles at a 1C discharge *** study introduces a novel technique for fabricating selective lithiophilic three-dimensional(3D)Cu current collectors,thereby enhancing the performance of li metal *** insights gained from this approach hold promise for enhancing the performance of all laser-processed 3D Cu current collectors by enabling precise lithiophilic modifications within complex structures.

关键词： copper current collector heat treatment laser processing lithium metal battery selective crystalline orientation