检索结果-南通市图书馆

An Envelope Algorithm for Single Nanoparticle Collision Electrochemistry

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2021年第7期39卷 1936-1940页

作者： chun-yu xu Ru-Jia yu xue Ni Su-Wen xu Xi-Xin Fu Yong-Jing Wan Yi-Lun Ying Yi-Tao Long School of Information Science and Engineering East China University of Science and TechnologyShanghai200237 China State Key Laboratory of Analytical Chemistry for Life Science School of Chemistry and Chemical EngineeringNanjing UniversityNanjingJiangsu210023 China Chemistry and Biomedicine Innovation Center Nanjing UniversityNanjingJiangsu210023 China Department of Chemistry East China University of Science and TechnologyShanghai200237 China

Main observation and conclusion Single nanoparticle collision has attracted great attention in the last several years to reveal the electron transfer and motion trajectories of individual particles at the electrode **... 详细信息

关键词： Analytical methods Electrochemistry Nanopartlcles Savitzky-Golay filter Single nanoparticle collision

Complete Convergence of Weighted Sums for Arrays of Rowwise m-negatively Associated Random Variables

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Mathematical Research 2014年第1期30卷 41-50页

作者： GUO MING-LE xu chun-yu ZHU DONG-JIN School of Mathematics and Computer Science Anhui Normal University

In this paper, we discuss the complete convergence of weighted sums for arrays of rowwise m-negatively associated random variables. By applying moment inequality and truncation methods, the sufficient conditions of complete convergence of weighted sums for arrays of rowwise m-negatively associated random variables are established. These results generalize and complement some known conclusions.

关键词： complete convergence negatively associated m-negatively associated,weighted sum

Numerical simulation of microstructure and microporosity morphology in directional solidification of aluminum-copper alloys:Effect of copper content and withdrawal rate

在线全文

学校读者我要写书评

暂无评论

China Foundry 2025年第1期22卷 33-44页

作者： Wei yuan Hai-dong Zhao xu Shen chun Zou yuan Liu Qing-yan xu National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials South China University of TechnologyGuangzhou 510640China Key Laboratory for Advanced Materials Processing Technology(Ministry of Education) Tsinghua UniversityBeijing 100084China

Microporosity formed in the solidification process of Al alloys is detrimental to the alloy properties.A two-dimensional cellular automaton(CA)model was developed to simulate the microstructure and microporosity formation in Al-Cu alloys,considering variations in Cu content and solidification *** results indicate that the Cu content primarily influences the growth of *** validate the model,directional solidification experiments were conducted on Al-Cu alloys with varing Cu contents and withdrawal *** experimental results of dendrites and microporosity characteristics agree well with the predictions from the developed model,thus confirming the validity of the *** alloy’s liquidus temperature,dendrite morphology,and hydrogen saturation solubility arising from different Cu contents have significant effects on microporosity *** withdrawal rate primarily affects the nucleation of hydrogen microporosity by altering cooling rates and dendritic growth rates,resulting in different microporosity characteristics.

关键词： microporosity dendrites cellular automaton Al-Cu alloys directional solidification

Elucidating Secondary Organic Aerosol Processes through High-Resolution Aerosol Mass Spectrometry in Beijing

在线全文

学校读者我要写书评

暂无评论

ADVANCES IN ATMOSPHERIC SCIENCES 2025年第4期42卷 670-681页

作者： xu, Weiqi Chen, chun Li, Zhijie Zhang, Zhiqiang Zhang, yu Wang, Zifa Sun, Yele Chinese Acad Sci Inst Atmospher Phys Key Lab Atmospher Environm & Extreme Meteorol Beijing 100029 Peoples R China Chinese Acad Sci Inst Atmospher Phys State Key Lab Atmospher Boundary Layer Phys & Atmo Beijing 100029 Peoples R China Univ Chinese Acad Sci Coll Earth & Planetary Sci Beijing 100049 Peoples R China Chinese Res Inst Environm Sci State Key Lab Environm Criteria & Risk Assessment Beijing 100012 Peoples R China China Meteorol Adm Training Ctr Beijing 100081 Peoples R China

Exploring secondary organic aerosol (SOA) processes is crucial for understanding climate and air pollution in megacities. This study introduces a new method using positive matrix factorization (PMF) to investigate the SOA process by integrating the OA and associated ions previously misidentified as inorganic aerosol in high-resolution aerosol mass spectrometry data. The mass spectra and time series of primary OA (POA) and less oxidized oxygenated OA (OOA) identified by this new method resembled those resolved by traditional PMF. However, more oxidized OOA (MO-OOA) identified by traditional PMF can be further subdivided into multiple OA factors, including nitrogen-enriched OA (ON-OA) and sulfur-enriched OA (OS-OA) in summer, and ON-OA, OS-OA, and OOA in winter. Our findings highlight the significant role of photochemical processes in the formation of OS-OA compared to ON-OA. The compositions of reconstructed MO-OOA varied under different Ox (= O3 + NO2) and relative humidity conditions, emphasizing the limitations of using a constant mass spectrum. Aged biomass burning OA (BBOA) and coal combustion OA (CCOA), previously misattributed as POA, contributed 9.2% (0.43 mu g m-3) and 7.0% (0.33 mu g m-3) to SOA, respectively. Aged BBOA was more prone to forming OS-OA, whereas ON-OA showed higher correlations with aged CCOA, indicating distinct molecular compositions of SOA from different aged POA sources. Compared to aged BBOA, aged CCOA was more subject to conversion during aqueous phase processing. These results suggest that the variations in mass spectra and compositions need to be considered when simulating SOA processes.

关键词： secondary organic aerosol positive matrix factorization aerosol mass spectrometry nitrogen-enriched organic aerosol sulfur-enriched organic aerosol

Risk factors for biometry prediction error by Barrett Universal II intraocular lens formula in Chinese patients

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Ophthalmology(English edition) 2025年第1期18卷 74-78页

作者： xu-Hao Chen Ying Hong Xiang-Han Ke Si-Jia Song yu-Jie Cen chun Zhang Beijing Key Laboratory of Restoration of Damaged Ocular Nerve Department of OphthalmologyPeking University Third HospitalBeijing 100191China State Key Laboratory of Ophthalmology Zhongshan Ophthalmic CenterSun Yat-sen UniversityGuangdong Provincial Key Laboratory of Ophthalmology and Visual ScienceGuangzhou 510060Guangdong ProvinceChina

AIM:To investigate the influence of postoperative intraocular lens(IOL)positions on the accuracy of cataract surgery and examine the predictive factors of postoperative biometry prediction errors using the Barrett Universal II(BUII)IOL formula for ***:The prospective study included patients who had undergone cataract surgery performed by a single surgeon from June 2020 to April *** collected data included the best-corrected visual acuity(BCVA),corneal curvature,preoperative and postoperative central anterior chamber depths(ACD),axial length(AXL),IOL power,and refractive *** formula was used to calculate the IOL *** mean absolute error(MAE)was calculated,and all the participants were divided into two groups *** t-tests were applied to compare the variables between *** regression analysis was used to analyze the influence of age,AXL,corneal curvature,and preoperative and postoperative ACD on ***:A total of 261 patients were *** 243(93.1%)and 18(6.9%)had postoperative MAE1 D,*** number of females was higher in patients with MAE>1 D(χ^(2)=3.833,P=0.039).The postoperative BCVA(logMAR)of patients with MAE>1 D was significantly worse(t=-2.448;P=0.025).After adjusting for gender in the logistic model,the risk of postoperative refractive errors was higher in patients with a shallow postoperative anterior chamber[odds ratio=0.346;95% confidence interval(CI):0.164,0.730,P=0.005].CONCLUSION:Risk factors for biometry prediction error after cataract surgery include the patient’s sex and postoperative *** with a shallow postoperative anterior chamber are prone to have refractive errors.

关键词： intraocular lens power calculation gender anterior chamber depth biometry prediction error

Blood collection procedures influence contamination rates in blood culture： a prospective study

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 Medical Journal 2011年第23期124卷 4002-4006页

作者： GE Ying LIU Xiao-qing xu Ying-chun xu Shan yu Min-hong ZHANG Wei DENG Guo-hua Department of Infectious Diseases Peking Union Medical College Hospital Chinese Academy of Medical Sciences ＆ Peking Union Medical College Beijing 100730 China

Background Blood culture contamination is a significant adverse event. The aim of this project was to evaluate the efficacy of a strict blood collection procedure in reducing the blood culture contamination rate. Methods A prospectively controlled study was performed in two different medical areas in Peking Union Medical College Hospital （PUMCH） for 16 months （from May 2006 to September 2007）. In test group, a strict blood collection procedure was carried out by trained nurses with the veinpuncture sites were scrupulously disinfected with 2.5% tincture of iodine plus 70% alcohol. In control group, commonly used procedure in PUMCH was performed with 0.45% chlorhexidine acetate plus 0.2% iodine. Blood culture positive results for 4 target organisms （Coagulase-negafive staphylococci, Propionibacterium acnes, physicians from infectious department to （contamination）. Corynebacterium species and Bacillus determine whether a sample was true species） were further assessed by positive （pathogen） or false positive Results Total 9321 blood culture collections were analyzed. The blood culture contamination rate in test group was significantly lower than that in control group （5/3177 （0.16%） vs. 77/6144 （1.25%）; x2=13.382, P 〈0.001）. The most common contaminant was Coagulase-negative staphylococcus （76.83%）. The average cultural time during which contaminated samples became positive was longer than that for true pathogen samples （42.0 hours vs. 13.9 hours, P=-0.041）. Conclusion Using a strict blood collection procedure can significantly reduce blood culture contamination rate.

关键词： blood culture contamination rate disinfection blood collection procedure

Permutation orbifolds of vertex operator superalgebras and associative algebras

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Mathematics 2025年第1期68卷 19-38页

作者： Chongying Dong Feng xu Nina yu Department of Mathematics University of California at Santa CruzSanta CruzCA 95064USA Department of Mathematics Huzhou UniversityHuzhou 313000 China Department of Mathematics University of California at RiversideRiversideCA 92521USA School of Mathematical Sciences Xiamen UniversityXiamen 361005China

Let V be a vertex operator superalgebra and g=(12···k)be a k-cycle which is viewed as an automorphism of the tensor product vertex operator superalgebra V^(■k).In this paper,we construct an explicit isomorphism from A_(g)(V^(■k))to A(V)if k is odd and to Aσ(V)if k is even whereσis the canonical automorphism of V of order 2 determined by the superspace structure of *** recover previous results by Barron(2016)and Barron and Vander Werf(2014)that there is a one-to-one correspondence between irreducible g-twisted V^(■k)-modules and irreducible V-modules(***σ-twisted V-modules)when k is odd(***).This explicit isomorphism is expected to be useful in our further study on the Zhu algebra of the fixed point subalgebra.

关键词： permutation orbifold vertex operator superalgebra Zhu algebra

Ideal Bi‑Based Hybrid Anode Material for Ultrafast Charging of Sodium‑Ion Batteries at Extremely Low Temperatures

在线全文

学校读者我要写书评

暂无评论

Nano-Micro Letters 2025年第3期17卷 152-167页

作者： Jie Bai Jian Hui Jia yu Wang chun Cheng Yang Qing Jiang Key Laboratory of Automobile Materials(Jilin University) Ministry of EducationSchool of Materials Science and EngineeringJilin UniversityChangchun 130022People’s Republic of China

Sodium-ion batteries have emerged as competitive substitutes for low-temperature applications due to severe capacity loss and safety concerns of lithium-ion batteries at−20°C or ***,the key capability of ultrafast charging at ultralow temperature for SIBs is rarely ***,a hybrid of Bi nanoparticles embedded in carbon nanorods is demonstrated as an ideal material to address this issue,which is synthesized via a high temperature shock *** a hybrid shows an unprecedented rate performance(237.9 mAh g^(−1) at 2 A g^(−1))at−60℃,outperforming all reported SIB anode *** with a Na_(3)V_(2)(PO_(4))_(3)cathode,the energy density of the full cell can reach to 181.9 Wh kg^(−1) at−40°*** on this work,a novel strategy of high-rate activation is proposed to enhance performances of Bi-based materials in cryogenic conditions by creating new active sites for interfacial reaction under large current.

关键词： Bi nanoparticles High temperature shock High-rate activation Ultrafast charging Low-temperature sodium-ion batteries

Prevalence and Treatment of Children＇s Asthma in Rura Areas Compared with Urban Areas in Beijing

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2015年第17期128卷 2273-2277页

作者： Wen-Jing Zhu Hai-Xia Ma Hui-Ying Cui xu Lu Ming-Jun Shao Shuo Li Yan-Qing Luo Qiang Wang chun-yu xu Dong-Qun xu Chuan-He Liu yu-Zhi Chen Center for Asthma Prevention and Education Capital Institute of Pediatrics Beijing 100020 China Department of Pediatrics Liangxiang Hospital Fangshan District Beijing 102401 China Department of Pediatrics Tongzhou Maternal and Child Health Hospital Beijing 101199 China Institute of Environmental Health and Related Product Safety Chinese Center for Disease Control and Prevention Beijing 100021 China

The prevalence of childhood asthma has been increasing in China. This study aimed to compare the prevalence, diagnosis, and treatment of asthmatic children from urban and rural areas in Beijing, China. Methods： Schools, communities, and kindergartens were randomly selected by cluster random sampling from urban and rural areas in Beijing. Parents were surveyed by the same screening questionnaires. On-the-spot inquiries, physical examinations, medical records, and previous test results were used to diagnose asthmatic children. Information on previous diagnoses, treatments, and control of symptoms was obtained. Results： From 7209 children in rural areas and 13,513 children in urban areas who completed screening questionnaires, 587 children were diagnosed as asthma. The prevalence of asthma in rural areas was lower than in urban areas （1.25% vs. 3.68%, χ^2 = 100.80, P 〈 0.001）. The diagnosis of asthma in rural areas was lower than in urban areas （48.9% vs. 73.9%, χ^2 = 34.6, P 〈 0.001）. Compared with urban asthmatic children （56.5%）, only 35.6% of rural asthmatic children received inhaled corticosteroids （P 〈 0.05）. The use ofbronchodilators was also lower in rural areas than in urban areas （56.5% vs. 66.4%, χ^2 = 14.2, P 〈 0.01）. Conclusion： The prevalence of asthma in children was lower in rural areas compared with children in the urban area of Bcijing. A considerable number of children were not diagnosed and inadequately treated in rural areas,

关键词： Asthma Children Diagnosis Treatment Rural Urban