检索结果-南通市图书馆

Thermal behaviors and growth of reduced ferronickel particles in carbon-laterite composites

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2011年第6期30卷 681-687页

作者： HUANG Donghua ZHANG Jianliang MAO Rui CAO Mingming School of Metallurgical and Ecological Engineen＇ng State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Beijing 100083 China Journals Publishing center University of Science and Technology Beijing Beijing 100083 China

The thermal behaviors of single laterite ore and graphite-laterite mixtures were investigated by thermogravimetry （TG）, derivative thermogravimetry （DTG）, and differential thermal analysis （DTA）. Four mass loss steps maximized at about 78, 272, 583, and 826℃ are observed for the laterite ore, representing the vaporization of free water, the dehydroxylation of goethite, the decomposition of serpentines, and the second dehydroxylation of serpentines, respectively. The reduction reactions of the graphite-laterite mixtures start at around 700℃ and can be divided into three major temperature regions. Coal-laterite composites with an addition of 10 wt.% CaO were roasted at 1100-1350℃ for 30 min, and the reduced samples were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results indi- cate that the reduction reactions proceed more completely at higher temperatures. The growth of the reduced ferronickel particles is greatly influenced by the roasting temperature, Obvious growth of the reduced ferronickel particles appears with the formation of worm-like crystals for the sample reduced at 1250℃ and spheric particles are observed for the sample reduced at 1300℃. When the reduction temperature increases to 1350℃, the reduced ferronickel particles agglomerate to ferronickel granules of 3-8 mm in diameter. The main elements in the granules include iron, nickel, chromium, carbon, and sulfur, with the content of nickel and that of iron of 9.08 wt.% and 85.21 wt.%, respectively.

关键词： laterite ferronickel granules dehydration reduction thermal analysis

Alkali-silica Reactivity of Different Aggregates from Mineral and Textural Characteristics

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of technology(Materials science) 2008年第6期23卷 901-906页

作者：莫祥银 Analysis and Testing center & Jiangsu Key Laboratory of Biofunctional Materials Nanjing Normal University

To identify the aggregates causing the alkali-silica reaction, and the reactivity of rocks in different parts of china, the mineral and texture characteristics of some typical coarse ag gregates and the alkali reactivity of these aggregates were systematically investigated. On one hand, petrographic examination of aggregates, combined with X-ray diffraction analysis, chemical analysis, scanning electron microscopy, was conducted for analyzing their mineralogy and texture. It was found that not only mineral characteristics, but also their interior structure would affect their potential alkali-silica reactivity. Furthermore, the alkali-silica reactivity of aggregates is due to their mineral compositions, such as containing different alkali-reactive minerals, while, different stuctures of those aggregates with similar minerals affect their reactivity to some extent. There are some amount of micro-aperture and cracks across the quartz in the aggregate, which may become the natural accesses for Na^＋, K^＋, and OH^- ions to intrude in the mortar or concrete during the process of alkali-silica reaction. Alkali-silica reactivity of the aggregates was detected by the accelerated mortar bars test. It was revealed that all the aggregates tested were alkali-silica reactive and the results were also in accordance with their mineral and structure analysis.

关键词： petrographic examination of aggregates study of thin sections x-ray diffraction analysis chemical analysis scanning electron microscopy

Study on Sulfide-melt Inclusions in Mantle Xenoliths of Xinchang, Zhejiang

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2000年第1期14卷 5-9页

作者： Jiuhua Xu Xuelei Chu YulingXie Fenglei Bie Dayi Qian University of science and technology Beijing, Beijing 100083, china china University of Geosciences, Beijing 100083, china The Research center of Mineral Resources Exploration, Chinese Academy Univ Sci & Technol Beijing Beijing 100083 Peoples R China china Univ Geosci Beijing 100083 Peoples R China Chinese Acad Sci Res Ctr Mineral Resources Explorat Beijing 100101 Peoples R China Chinese Acad Sci Inst Geol Beijing 100029 Peoples R China

In minerals of mantle xenoliths captured within Tertiary alkali-basalt from Xinchang, Zhejiang province, china, many sulfidemelt inclusions were found by the observation of polished thin section. Electron microprobe analysis has been applied to detect the components of sulfide-melt inclusions. The result shows that the sulfide phases of inclusions are mainly pentlandite, and secondarily pyrrho- tite, The molar ratio of Ni to Fe, r_Ni,/r_Fe, of mineral phases in sulfide inclusions is related to olivine contents in host mantle xenoliths. The r_Ni/r_Ni, of sulfides from Xinchang samples has a possitive correlation to r_(Fe+Ni),/r_S. The r_(Fe+Ni),/r_S, becomes higher with the increasing of r_Ni/r_Fe In single sulfide-melt inclusions, r_Ni,/r_Fe, r_(Fe+Ni),/r, and Ni contents increase from the center to edge, reflecting a result of different cooling speed in an inclusion. A comparison between the data from Hannuoba, West Eifel of Germany and Nograd-Gomor of east Europe suggests that the composition of the inclusions is different for each area, which indicated that a regional differentiation of sulfide in mantle fluids.

关键词： mantle xenolith sulfide-melt inclusion electron microprobe analysis, Xinchang

Association between ICU quality and in-hospital mortality of V-V ECMO-supported patients—the ECMO quality improvement action(EQIA)study:a national cohort study in china from 2017 to 2019

在线全文

学校读者我要写书评

暂无评论

Frontiers of Medicine 2024年第2期18卷 315-326页

作者： Wei Cheng Jieqing Chen Xudong Ma Jialu Sun Sifa Gao Ye Wang Longxiang Su Lu Wang Wei Du Huaiwu He Yujie Chen Zunzhu Li Qi Li Jianhua Sun Hongbo Luo Jinbang Liu Guangliang Shan Bing Du Yanhong Guo Dawei Liu Chang Yin Xiang Zhou on behalf of the china National Critical Care Quality Control center-the ECMO quality improvement action(EQIA)study Department of Critical Care Medicine State Key Laboratory of Complex Severe and Rare DiseasesPeking Union Medical College HospitalChinese Academy of Medical Science and Peking Union Medical CollegeBeijing100730China Information center Department/Department of Information Management State Key Laboratory of Complex Severe and Rare DiseasesPeking Union Medical College HospitalPeking Union Medical College&Chinese Academy of Medical SciencesBeijing100730China Department of Medical Administration National Health Commission of the People’s Republic of ChinaBeijing100044China School of Population Medicine and Public Health Chinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing100730China Department of Epidemiology and Biostatistics Institute of Basic Medicine SciencesChinese Academy of Medical Sciences(CAMS)&School of Basic MedicinePeking Union Medical CollegeBeijing100730China National Institute of Hospital Administration National Health Commission of the People’s Republic of ChinaBeijing100044China 不详

This cohort study was performed to explore the influence of intensive care unit(ICU)quality on in-hospital mortality of veno-venous(V-V)extracorporeal membrane oxygenation(ECMO)-supported patients in *** study involved all V-V ECMO-supported patients in 318 of 1700 tertiary hospitals from 2017 to 2019,using data from the National Clinical Improvement System and china National Critical Care Quality Control *** quality was assessed by quality control indicators and capacity *** the 2563 V-V ECMO-supported patients in 318 hospitals,a significant correlation was found between ECMO-related complications and *** reintubation rate within 48 hours after extubation and the total ICU mortality rate were independent risk factors for higher in-hospital mortality of V-V ECMO-supported patients(cutoff:1.5%and 7.0%;95%confidence interval:1.05–1.48 and 1.04–1.45;odds ratios:1.25 and 1.23;P=0.012 and P=0.015,respectively).Meanwhile,the V-V ECMO center volume was a protective factor(cutoff of≥50 cases within the 3-year study period;95%confidence interval:0.57–0.83,odds ratio:0.69,P=0.0001).The subgroup analysis of 864 patients in 11 high-volume centers further strengthened these ***,ICU quality may play an important role in improving the prognosis of V-V ECMO-supported patients.

关键词： veno-venous extracorporeal membrane oxygenation in-hospital mortality high-volume centers quality control intensive care unit capacity parameters

Solvothermal synthesis of crystalline carbon nitrides

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

Chinese science Bulletin 2003年第6期48卷 519-522页

作者： L Qiang, CAO Chuanbao & ZHU Hesun Research center of Materials science, Beijing Institute of technology, Beijing 100081, china Research center of Materials science Beijing Institute of Technology China

A solvothermal reaction of anhydrous C3N3Cl3 and Li3N using benzene as the solvent has been carried out to prepare crystalline carbon nitrides successfully at 350℃ and 5—6 MPa. X-ray diffraction (XRD) indicated that the major part of our brown sample was mainly composed of a-C3N4 and b-C3N4 with lattice parameters of a = 0. 65 nm, c = 0.47 nm for a-C3N4 and a = 0.644 nm, c = 0. 246 nm for b-C3N4, which match the latest ab-initio calculations quite well. The N/C ratio in the powder is about 0.66. The Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spec-troscopy (XPS) analyses suggested the presence of both sin-gle and double carbon-nitrogen bonds. The kinetics effects of our solvothermal reaction to prepare crystalline carbon ni-trides are also discussed chiefly.

关键词：氮化碳晶体 β-C3N4 溶解热法合成超硬材料 α-C3N4

Galvanic effects on cavitation damage for 1Cr13 stainless steel

在线全文

学校读者我要写书评

暂无评论

Journal of University of science and technology Beijing 2003年第4期10卷 33-37页

作者： Dongbai Sun, Xia Bai, Hongying Yu, Huimin Meng, and Huiqing LiUNDP-Beijing Corrosion and Protection center, University of science and technology Beijing, Beijing 100083, china UNDP Corrosion Ctr. Univ. of Sci. and Technol. Beijing Beijing 100083 China

Based on the electric-spark principle, a new kind of cavitation damagetesting apparatus was designed, which could produce the bubble. Bubbles collapsed and acted on asmall surface area of the alloy surface, so an intensive electrochemical inhomogenous state would beinduced and lead to the existence of surface galvanic effect on the alloy. The galvanic effect of1Cr13 SS during cavitation damage has been quantitatively investigated in NaCl solution. The resultsshow that intensive galvanic effect of 1Cr13 SS during cavitation damage appears the potential ofthe damaged area shifting negatively with the bubble collapse and simultaneously the galvaniccurrent generates. The mass loss of alloy due to cavitation increases with the bubble quantity, andincreases with the increasing of Cl- content. And both the total mass loss and the mass loss due togalvanic corrosion increase linearly with the area ratio of cavitation damaged to undamaged *** surface galvanic effects speed up the dissolution rate of the alloy, which, in turn,accelerates the mechanical damage, and aggravates the mass loss of the alloy. It has been furtherconfirmed that the mass loss due to the surface galvanic effect can be decreased by catholicprotection.

关键词： cavitation damage galvanic effect area ratio mass loss

Effects of complexing agents on acidic electroless nickel deposition

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2010年第4期29卷 401-406页

作者： JIN Ying YU Hongying YANG Dejun SUN Dongbai National center for Materials Service Safety University of Science and Technology Beijing Beijing 100083 China Corrosion andProteetion center School of Materials Science andEngineering University of Science and Technology Beijing Beij'ing 100083 China

Our previous study reported the influences of different complexing agents on electroless nickel （EN） by examining the properties of the deposits. In the present work, the effects of four common-used complexing agents on EN deposition rate and the stability of solution pH values were examined, either with an acetic pH buffer agent or absent of them. It is indicated that the pH buffeting effect of them is dominative when the EN solution is lack of the pH buffer. Under this situation, the EN deposition rate increases with the concentration of complexing agents increasing. The EN deposition rate decreases with fin＇ther adding the complexing agent when the solution already has enough pH buffer capability. Electrochemical impedance spectroscopy obtained during EN deposition illustrates that, in this case, the enhanced reaction resistance is the main reason for a lower deposition rate. However, the influence of polarization caused by mass transfer is not negligible at high complex ratio for sodium citrate and malic acid EN solutions.

关键词： electroless nickel complexing agents electrochemical impedance spectrum reaction resistance pH value

FRACTAL GEOMETRY STUDY OF CORRELATION BETWEEN IMPACT TOUGHNESS OF STEEL AND PARAMETERS OF FREE-CUTTING PHASE

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1992年第4期5卷 250-255页

作者： JIANG Laizhu CUI Kun Huazhong University of science and technology,Wuhan,china Huazhong Univ of science and Technology Wuhan China

studies were made of the calculation of fractal dimension of transverse impact fracture sur- face,and of the correlation between impact toughness of steel and parameters of free-cutting phase by means of the developed fractal geometry model of crack *** is believed that the area fraction,f,of free-cutting phase is negligibly influential to the longitudinal im- pact toughness,as f1 .While the aspect ratio,saying ratio of length to width,of free-cut. ting phase is inversely influential to the transverse impact *** may .be the reason why the transverse impact toughness of free-cutting steel containing more rare earth contrast to sulphur is even higher than the low sulphur containing steel.

关键词： fractal geometry impact toughness free-cutting phase

Air-sea heat flux exchange over the South china Sea under different weather conditions before and after southwest monsoon onset in 2000

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2003年第3期22卷 369-383页

作者： Junyue Yan, Huadong Yao, Jianglong Li, Zhiyi Tang, Guorong Jiang, Wenyu Sha, Xunqiang Li, Yiguo Xiao National Climate center, Beijing 100081, china. E-mail: yanjy@cma.gov.cnPLA University of science technology, nanjing 211101, china Natl Climate Ctr Beijing 100081 Peoples R China PLA Univ Sci Technol Nanjing 211101 Peoples R China

With the data observed from the Second SCS Air-Sea Flux Experiment on the Xisha air-sea flux research tower, the radiation budget, latent, sensible heat fluxes and net oceanic heat budgets were caculated before and after summer monsoon onset. It is discovered that, after summer monsoon onset, there are considerable changes in air-sea fluxes, especially in latent heat fluxes and net oceanic heat budget. Furthermore, the analyzed results of five synoptic stages are compared. And the characteristics of the flux transfer during different stages around onset of South china Sea monsoon are discussed. The flux change shows that there is an oceanic heat accumulating process during the pre-onset and the break period, as same as oceanic heat losing process during the onset period. Moreover, latent fluxes, the water vapor moving to the continent, even the rainfall appearance in Chinese Mainland also can be influenced by southwester. Comparing Xisha fluxes with those obtained from the Indian Ocean and the western Pacific Ocean, their differences may be observed. It is the reason why SSTs can keep stable over the South china Sea while they decrease quickly over the Arabian Sea and the Bay of Bengal after monsoon onset.

关键词： South china Sea air-sea heat fluxes South china Sea monsoon