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快速协同浊点萃取-分光光度法测定水中六价铬

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中国卫生检验杂志 2016年第22期26卷 3217-3220页

作者：杨静程健琳杨胜园何爱桃陈丹向艳衡阳市产商品质量监督检验所湖南衡阳421001 南华大学公共卫生学院湖南衡阳421001

目的建立快速协同浊点萃取-分光光度法测定六价铬的新方法。方法在强酸性条件下,Triton X-100与正辛醇形成快速浊点萃取体系,室温下溶液分为两相,Cr(Ⅵ)与PAN形成的金属螯合物进入富胶束相中,达到快速分离富集的目标,采用分光光度法直... 详细信息

目的建立快速协同浊点萃取-分光光度法测定六价铬的新方法。方法在强酸性条件下,Triton X-100与正辛醇形成快速浊点萃取体系,室温下溶液分为两相,Cr(Ⅵ)与PAN形成的金属螯合物进入富胶束相中,达到快速分离富集的目标,采用分光光度法直接测定富胶束相中富集的Cr(Ⅵ)。结果当Cr(Ⅵ)浓度为1.3μg/L^18.0μg/L时,吸光度值F与Cr(Ⅵ)浓度成线性关系,线性回归方程为y=0.008 5x+0.522 1,相关系数(r)为0.998,检出限为0.40μg/L,相对标准偏差为3.2%~5.3%。环境水样加标回收率为96.9%~103.9%。结论本方法所用仪器简单,操作方便,可用于实际水样中Cr(Ⅵ)含量的检测。

关键词： 1-(2-吡啶偶氮)-2-萘酚快速协同浊点萃取非离子表面活性剂Triton X-100 分光光度法铬

Marginal-restraint mandrel-free spinning process for thin-walled ellipsoidal heads

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Advances in Manufacturing 2020年第2期8卷 189-203页

作者： Yong-cheng Lin Jia-yang Chen Dao-Guang He Xin-He Li jian yang School of Mechanical and Electrical Engineering Central South UniversityChangsha 410083People's Republic of China State Key Laboratory of High Performance Complex Manufacturing Changsha 410083People's Republic of China Light Alloy Research Institute Central South UniversityChangsha 410083People's Republic of China

Metal sheet spinning is an advanced near-net forming technology for the manufacture of thin-walled ellipsoidal *** exact control of dimensional accuracy,however,is a considerable problem for spinning thinwalled parts with large diameter-to-thickness *** this work,a marginal restraint mandrel-free spinning process with two passes is proposed for the fabrication of thinwalled ellipsoidal heads without wrinkling.A finite element model is established and verified to study the influences of spinning parameters on the dimensional precision of thin-walled ellipsoidal *** is found that the spinning parameters considerably influence the deviations of wall thickness and contour characteristics.A small forming angle or small roller fillet radius during the first pass spining,as well as the small angle between passes or high feed ratio during the second pass spinning,can improve the wall thickness ***,as the forming angle or feed ratio is increased during the first pass spinning,the contour precision initially increases and then *** the second pass spinning,the contour precision can be improved at a small angle between passes,whereas it deteriorates at a larger roller installation *** optimized spinning parameters are obtained and verified by experiments.

关键词： Alloy Thin-walled ellipsoidal heads Spinning Finite element model Dimensional precision

Localization of elastic waves in one-dimensional detuned phononic crystals with flexoelectric effect

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International Journal of Smart and Nano Materials 2022年第2期13卷 244-262页

作者： cheng Shen Yifan Kong Tian jian Lu Shasha yang State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjingPRChina MIIT Key Laboratory of Multifunctional Lightweight Materials and Structures Nanjing University of Aeronautics and AstronauticsNanjingPRChina Space Structure and Mechanism Technology Laboratory of China Aerospace Science and Technology Group Co.Ltd ShanghaiP.R China School of Mechanical Engineering Nanjing Vocational University of Industry TechnologyNanjingP.R China

Although forbidden band effect in perfectly periodic phononic crystals(PC)is very attractive,random disordered(***)phenomenon is inevitable in engineering processing,thus explor-ing the effect of detuning on the wave characteristics of PC becomes a *** this study,fundamental governing equa-tions and boundary conditions are derived from the principle of virtual *** characteristics and localization factor of one-dimensional(1D)detuned nano-PC are investigated based on the transfer matrix method,with flexoelectric effect duly accounted ***,with BaTiO_(3)􀀀SrTiO_(3) nano-PC taken for illustration,forbidden band properties and localization factor of 1D elastic waves in harmonic and detuned states are systematically *** is demonstrated that localization factor can characterize the energy band structure of 1D PC *** effect tends to widen the width of forbidden band with increasing detuning,and detuning is linearly related to the *** forbidden band is more sensitive to flexoelectric coefficient detuning than thickness *** research results provide useful theoretical guidance for designing high-frequency nanoscaled devices with the function of filtering based on band gap effect of nano-PC.

关键词： Flexoelectric effect phononic crystal detuning localization factor forbidden band

A novel enhancement method for low illumination images based on microarray camera

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Applied Mathematics(A Journal of Chinese Universities) 2017年第3期32卷 313-322页

作者： ZOU jian-cheng ZHENG Wen-qi yang Zhi-hui Institute of Image Processing and Pattern Recognition North China University of Technology Beijing 100144 China.

It is difficult but important to get clear information from the low illumination images. In recent years the research of the low illumination image enhancement has become a hot topic in image processing and computer vision. The Retinex algorithm is one of the most popular methods in the field and uniform illumination is necessary to enhance low illumination image quality by using this algorithm. However, for the different areas of an image with contrast brightness differences, the illumination image is not smooth and causes halo artifacts so that it cannot retain the detail information of the original images. To solve the problem, we generalize the multi-scale Retinex algorithm and propose a new enhancement method for the low illumination images based on the microarray camera. The proposed method can well make up for the deficiency of imbalanced illumination and significantly inhibit the halo artifacts as well. Experimental results show that the proposed method can get better image enhancement effect compared to the multi-scale Retinex algorithm of a single image enhancement. Advantages of the method also include that it can significantly inhibit the halo artifacts and thus retain the details of the original images, it can improve the brightness and contrast of the image as well. The newly developed method in this paper has application potential to the images captured by pad and cell phone in the low illumination environment.

关键词： low illumination microarray camera multi-scale Retinex image sharpening

A systematic,updated review of Xuezhikang,a domestically developed lipid-lowering drug,in the application of cardiovascular diseases

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Acta Pharmaceutica Sinica B 2024年第10期14卷 4228-4242页

作者： cheng yang Yongjian Wu Jie Qian jian-Jun Li Cardiometabolic Center Key Laboratory of Cardiovascular DiseaseFuwai HospitalNational Center for Cardiovascular DiseasesChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100037China

Cardiovascular diseases(CVDs)are a major threat to public health globally.A large proportion of people with dyslipidaemia have poorly controlled lipid levels,emphasizing the need for alternative lipid-lowering treatments that are both effective and ***,a red yeast rice(RYR)extract,containing 13 kinds of monacolins and other bioactive components,emerges as one such promising *** discovery was built on a long history of RYR use as a functional food supplement and traditional Chinese *** randomized,controlled clinical trials have substantiated its lipid-lowering effects and its potential to protect against *** concerns with statins did not arise during decades of experience with Xuezhikang treatment in clinical *** approval of Xuezhikang in multiple regions of Asia marked a conceptual shift in CVD management,moving from single agents to polypills and from synthetic medicines to natural *** review comprehensively addresses important topics related to this medicinal natural extract,including the ancient utilization of RYR,the development of Xuezhikang,its mechanisms of action,pleiotropic effects,clinical studies,challenges,and future perspectives to enhance our understanding regarding the role of Xuezhikang,a representative,domestic lipid-lowering drug of RYR,in prevention and treatment of CVD.

关键词： Red yeast rice Xuezhikang Natural extract Traditional Chinese medicine Cardiovascular disease Dyslipidaemia Lipid-lowering Cardiovascular prevention

Rapid construction of the unique BCD ring system of tricyclo[6.2.1.0]undecane in the C_(19)-diterpenoid alkaloid aconitine

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Chinese Chemical Letters 2017年第8期28卷 1788-1792页

作者： Xue yang Bin cheng Hang cheng Liang Xu jian-Li Wang Key Laboratory of Drug Targeting Ministry of EducationDepartment of Chemistry of Medicinal Natural ProductsWest China College of PharmacySichuan UniversityChengdu610041China State Key Laboratory of Oral Disease West China School of StomatologySichuan UniversityChengdu610041China

A model study leading to the preparation of the unique tricyclo [6.***.1.0] undecane BCD ring systems of aconitine is described. The synthesis features an unprecedented diastereoselective oxidative dearomatization/dimer... 详细信息

关键词： Aconitine Diterpenoid alkaloid Diels-Alder reaction Cascade reaction Wagner-Meerwein rearrangement

Wear Behavior of Cold Pressed and Sintered Al_2O_3/TiC/CaF_2-Al_2O_3/TiC Laminated Ceramic Composite

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Acta Metallurgica Sinica(English Letters) 2013年第2期26卷 157-166页

作者： Xuefeng yang jian cheng Peilong SONG Shouren WANG Liying yang Yanjun WANG Ken MAO School of Mechanical Engineering University of Jinan Key Laboratory for Anisotropy and Texture of Materials of the Ministry of Education Northeastern University School of Engineering Warwick University

A novel laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite was fabricated through cold pressing and sintering to achieve better anti-wear performance, such as low friction coefficient and low wear rate. Al2O3/TiC/CaF2 and Al2O3/TiC composites were alternatively built layer-by-layer to obtain a sandwich structure. Solid lubricant CaF2 was added evenly into the Al2O3/TiC/CaF2 layer to reduce the friction and wear. Al2O3/TiC ceramic was also cold pressed and sintered for comparison. Friction analysis of the two ceramics was then conducted via a wear-and-tear machine. Worn surface and surface compositions were examined by scanning electron microscopy and energy dispersion spectrum, respectively. Results showed that the laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite has lower friction coefficient and lower wear rate than those of Al2O3/TiC ceramic alone because of the addition of CaF2 into the laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite. Under the friction load, the tiny CaF2 particles were scraped from the Al2O3/TiC/CaF2 layer and spread on friction pairs before falling off into micropits. This process formed a smooth, self-lubricating film, which led to better anti-wear properties. Adhesive wear is the main wear mechanism of Al2O3/TiC/CaF2 layer and abrasive wear is the main wear mechanism of Al2O3/TiC layer.

关键词： Friction and wear characteristics Wear property Ceramic-matrix compos-ites Layer manufacture Surface appearance Sliding

Influence of Extrusion Joint on Microstructural Evolution and Properties of Mg Alloy Sheet

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Acta Metallurgica Sinica(English Letters) 2016年第5期29卷 475-482页

作者： Qing-Shan yang Zu-jian Yu Hu-cheng Pan Qing-Wei Dai jian-Hui Li School of Metallurgy and Materials Engineering Chongqing University of Science and TechnologyChongqing 401331China Chongqing Academy of Science and Technology Chongqing 401123China Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) Northeastern UniversityShenyang 110819China

The mechanical behaviour of AZ31 magnesium alloy sheet with the extrusion joint （EJ） was evaluated. Extruded joint of AZ31 alloy sheets was obtained by the hot extrusion process. Tensile tests were carried out along the extrusion direction at room temperature, and both the non-uniform plastic deformation and the fracture behaviour were studied. It is found that the samples with EJ present significantly deteriorated mechanical properties compared with the EJ- free counterpart. Inhomogeneous rnicrostructure distribution around EJ zone brings in the uncoordinated deformation due to the high density of {1012} twins which were readily activated during plastic deformation.

关键词： Mg alloy Microstructure Twin Texture Extrusion joint

A Cation-Driven Approach toward Deep-Ultraviolet Nonlinear Optical Materials

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Research 2023年第3期2023卷 781-791页

作者： Cong Hu Meng cheng Wenqi Jin jian Han Zhihua yang Shilie Pan Research Center for Crystal Materials CAS Key Laboratory of Functional Materials and Devices for Special EnvironmentsXinjiang Technical Institute of Physics&ChemistryCAS40–1 South Beijing RoadUrumqi 830011China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

The design of new materials with special performances is still a great challenge,especially for the deep-ultraviolet nonlinear optical materials in which it is difficult to balance large bandgaps and strong second harmonic generation responses due to their inverse *** variation not only influences the whole structure frameworks but also directly participates in the formation of electronic structures,both of which could lead to the uncontrollability of the properties of the designed ***,a novel approach,aiming at purposeful and foreseeable material designs,is proposed to characterize the role of *** the verification of several series of borates,the influences of cation variation on property changes are explored ***,a feasible strategy of designing deep-ultraviolet nonlinear optical materials by substituting barium for lead has been concluded,which could obviously blue-shift the ultraviolet cutoff edge and maintain the relatively strong second harmonic generation response(more than 2 times of KH2PO4),achieving the property optimization,and especially works efficiently in *** property optimization design strategy and the cation characterization method are not only helpful in exploring nonlinear optical materials but also enlightening in material design and selection.

关键词： materials ultraviolet property