检索结果-南通市图书馆

Chinese Physics B 2024年第6期33卷 605-612页

作者：毛党新吴园燕涂育松 College of Physics Science and Technology Yangzhou UniversityYangzhou 225009China

The hydroxyl-terminated self-assembled monolayer(OH-SAM),as a surface resistant to protein adsorption,exhibits substantial potential in applications such as ship navigation and medical implants,and the appropriate strategies for designing anti-fouling surfaces are ***,we employ molecular dynamics simulations and alchemical free energy calculations to systematically analyze the factors influencing resistance to protein adsorption on the SAMs terminated with single or double OH groups at three packing densities(∑=2.0 nm^(-2),4.5 nm^(-2),and 6.5 nm^(-2)),*** the first time,we observed that the compactness and order of interfacial water enhance its physical barrier effect,subsequently enhancing the resistance of SAM to protein ***,the spatial hindrance effect of SAM leads to the embedding of protein into SAM,resulting in a lack of resistance of SAM towards ***,the number of hydroxyl groups per unit area of double OH-terminated SAM at ∑=6.5 nm^(-2) is approximately 2 to 3 times that of single OH-terminated SAM at ∑=6.5 nm^(-2) and 4.5 nm^(-2),consequently yielding a weaker resistance of double OH-terminated SAM towards ***,due to the structure of SAM itself,i.e.,the formation of a nearly perfect ice-like hydrogen bond structure,the SAM exhibits the weakest resistance towards *** study will complement and improve the mechanism of OH-SAM resistance to protein adsorption,especially the traditional barrier effect of interfacial water.

关键词： molecular dynamics simulation self-assembled monolayer resistance to protein adsorption hydrogen bond interfacial water

REACTION CHEMISTRY RELATED TO FCC GASOLINE QUALITY

在线全文

学校读者我要写书评

暂无评论

石油学报（石油加工） 2001年第1期17卷 70-71页

作者： HE Ming yuan, yan Li jun (Research Institute of Petroleum Processing, Beijing 100083, China) Research Institute of Petroleum Processing 北京 100083

About 80% of the gasoline pool as a whole in China for supplying the domestic market at current stage directly originates from FCC units. Obviously, FCC gasoline quality is critical for refiners to meet the nations more and more stringent gasoline specifications. FCC process is expected to produce gasoline with reduced contents of olefins, aromatics, benzene, sulfur, and, contradictorily, still with high octane number. Catalytic cracking process involves a series of acid catalyzed reactions. Bronsted acid sites dominate the surface of the catalyst used for FCC process. All the reactions of hydrocarbons in FCC process are based on carbonium ions of penta coordinated, or carbenium ions of tri coordinated. The monomolecular beta scission mechanism for alkane cracking explains that the cracking of carbon carbon bonding occurs at the beta position to the carbon atom bearing positive charge, and hence forms two small hydrocarbon molecules: one alkane molecule and one olefin molecule. The molar ratio of alkane to olefin for the primary cracking product will be 1 and it will be less than 1 if the cracking reaction proceeds. However, it is proved that bimolecular reaction pathways exist between surface carbenium ions and the feed molecules. The products of this bimolecular disproportionation reaction could be an alkane molecule and a newly formed carbenium ion. The better understanding of the reaction chemistry of FCC process based on monomolecular pathways and bimolecular pathways should be the basis for searching approaches to the improvement of FCC gasoline quality. In the complicated reaction scheme of the FCC process, the isomerization reaction leading to the formation of iso alkanes is obviously a target reaction, which favors both olefin reduction and octane enhancement. The cracking of small paraffin molecules, due to its limited number of reaction pathways and products, has been used to investigate cracking mechanism. In the present work the cracking of n hexane on

关键词： FCC 汽油反馈条件裂化工艺热转化

DNA-silver Nanocluster Binary Probes for Ratiometric Fluorescent Detection of HPV-related DNA

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2019年第4期35卷 581-585页

作者： yuan yan LI Shaoyuan LUO Lei WANG Qing FANG Hongmei HUANG Jin LIU Jianbo yanG Xiaohai WANG Kemin State Key Laboratory of Chemo/Biosensing and Chemometrics College of Chemistry and Chemical Engineering Key Laboratory for Bio-nanotechnology and Molecular Engineering of Hunan Province Hunan University Changsha 410082 P. R. China

Herein, we described a ratiometric strategy based on "chameleon" DNA-silver nanoclusters( DNA-AgNCs) fluorescent binary probes. The strategy was applied to detect high-risk human papillomavirus( HPV) DNA sequences, HPV-16. First, DNA-AgNCs were synthesized by a simple reduction method. The obtained nanoprobes showed typical yellow and red fluorescence of AgNCs. Upon the addition of HPV-16 DNA, the yellow fluorescence of AgNCs was reduced greatly, whereas tlie red fluorescence of AgNCs was increased. The concentration of HPV-16 DNA in the samples was characterized by the ratio of fluorescence intensity at 570 and 630 nm. Tlie ratiometric nanoprobes showed good selectivity for HPV-16 DNA, and the detection limit was 2 ninol/L. In addition, the practical applicability of this strategy was demonstrated by analysing the HPV-16 DNA in hiunan serum, illustrating its potential promise for clinical diagnosis.

关键词： DNA-silver nanocluster Ratiometric Binary probe Human papillomavinis

Potassium deficiency inhibits steviol glycosides synthesis by limiting leaf sugar metabolism in stevia(Stevia rebaudiana Bertoni)plants

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2021年第11期20卷 2932-2943页

作者： SUN Yu-ming HUANG Xiao-lei ZHANG Ting yanG Yong-heng CHENG Xiao-fang XU Xiao-yang yuan Hai-yan Jiangsu Key Laboratory for the Research and Utilization of Plant Resources/The Jiangsu Provincial Platform for Conservation and Utilization of Agricultural Germplasm Institute of BotanyJiangsu Province and Chinese Academy of SciencesNanjing 210014P.R.China College of Resources and Environment Shanxi Agricultural UniversityTaigu 030801P.R.China College of Arts and Sciences Shanxi Agricultural UniversityTaigu 030801P.R.China

The steviol glycosides(SGs)in stevia(Stevia rebaudiana Bertoni)leaves are becoming increasingly valuable due to its high sweetness but low calorific value,which is driving the development of stevia commercial *** fertilization management can effectively increase SGs productivity,but knowledge on the relationship between potassium(K)fertilization and SGs production is still *** this study,pot experiments were conducted in order to investigate the effect of K deficiency on SGs synthesis in stevia leaves,as well as the underlying *** results showed that when compared with standard K fertilization,K deficiency treatment has no significant effect on the biomass of stevia plant grown in a given soil with high K ***,K deficiency critically decreased leaf SGs contents as well as the expression of SGs synthesis-related *** contents of different sugar components decreased and the activities of sugar metabolism-related enzymes were inhibited under the K deficiency ***,spraying sucrose on the leaves of stevia seedlings diminished the inhibitory effect caused by K *** results also revealed the significant positive correlations between sucrose,glucose and SGs ***,our results suggest that K deficiency would suppress the synthesis of SGs in stevia leaves,and this effect may be mediated by the leaf sugar *** findings provide new insights into the improvement of SGs production potential.

关键词： Stevia rebaudiana Bertoni steviol glycosides potassium deficiency sugar metabolism

Anthropomorphic hand based on twisted-string-driven da Vinci’s mechanism for approaching human dexterity and power of grasp

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2022年第10期23卷 771-782页

作者： Yong-bin JIN Shao-wen CHENG yan-yan yuan Hong-tao WANG Wei yanG Center for X-Mechanics Zhejiang UniversityHangzhou 310027China ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang UniversityHangzhou 311200China State Key Laboratory of Fluid Power and Mechatronic System Zhejiang UniversityHangzhou 310027China Institute of Applied Mechanics Zhejiang UniversityHangzhou 310027China

Designing anthropomorphic prosthetic hands that approach human-level performance remains a great *** prosthetics are still inferior to human hands in several important properties, such as weight, size, fingertip force,grasp velocity, and active and passive dexterities. We present a novel design based on the under-actuated da Vinci’s mechanism driven by a flexible twisted string actuator(TSA). The distributed drive scheme allows structural optimization using a motion capture database to reproduce the natural movement of human hands while keeping adaptability to free-form objects. The application of TSA realizes a high conversion from motor torque to tendon contraction force while keeping the structure light,flexible, and compact. Our anthropomorphic prosthetic hand, consisting of six active and 15 passive degrees of freedom, has a weight of 280 g, approximately 70% of that of a human hand. It passed 30 of the 33 Feix grasp tests on objects in daily living and retained a loading capacity of 5 kg. This simple but intelligent mechanism leads to excellent stability and adaptability and renders feasible wide applications in prosthetics and in service robots.

关键词： Anthropomorphic hand da Vinci’s mechanism Twisted string actuator(TSA) Intelligent mechanism Principal component analysis(PCA)

PM_(2.5) obtained from urban areas in Beijing induces apoptosis by activating nuclear factor-kappa B

在线全文

学校读者我要写书评

暂无评论

Military Medical Research 2017年第4期4卷 200-209页

作者： Hui Peng Xiao-Hong Zhao Ting-Ting Bi Xiao-yan yuan Jia-Bin Guo Shuang-Qing Peng Evaluation and Research Center for Toxicology Institute of Disease Control and Prevention Academy of Military Medical Sciences Beijing Key Laboratory of Bioactive Substances and Functional Foods Beijing Union University

Background: Particulate matter(PM), which has adverse effects on citizen health, is a major air pollutant in Beijing city. PM_(2.5) is an indicator of PM in urban areas and can cause serious damage to human health. Many epidemiological studies have shown that nuclear factor-kappa B(NF-κB) is involved in PM_(2.5)-induced cell injury, but the exact mechanisms are not well ***: The cytotoxic effects of PM_(2.5) at 25–1600μg/ml for 24 h were determined by MTT assay in Chinese hamster ovary cells(CHO) cells. Flow cytometry was used to determine the apoptosis rate induced by PM_(2.5). The destabilized enhanced green fluorescent protein(d2 EGFP) green fluorescent protein reporter system was used to determine the NF-κB activity induced by PM_(2.5). The expression of pro-apoptotic Bcl-2-associated death promoter(BAD) proteins induced by PM_(2.5) was determined by Western blotting to explore the relationship between PM_(2.5) and the NF-κB signaling pathway and to determine the toxicological mechanisms of PM_(2.5).Results: PM_(2.5) collected in Beijing urban districts induces cytotoxic effects in CHO cells according to MTT assay with 72.28% cell viability rates even at 200μg/ml PM_(2.5) and flow cytometry assays with 26.97% apoptosis rates at 200μg/ml PM_(2.5). PM_(2.5) increases the activation levels of NF-κB, which have maintained for 24 h. 200μg/ml PM_(2.5) cause activation of NF-κB after exposure for 4 h, the activation peak appears after 13.5 h with a peak value of 25.41%. The average percentage of NF-κB activation in whole 24 h is up to 12.90% by 200μg/ml PM_(2.5). In addition, PM_(2.5) decreases the expression level of the pro-apoptotic protein BAD in a concentration-dependent ***: PM_(2.5) induces NF-κB activation, which persists for 24 h. The expression of pro-apoptotic protein BAD decreased with increased concentrations of PM_(2.5). These findings suggest that PM_(2.5) plays a major role in apoptosis by activating the NF-κB signaling path

关键词： Particulate matter NF-κB pathway Apoptosis BAD protein

Vertical direction impaction of kissing molars:A case report

在线全文

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2022年第12期10卷 3959-3965页

作者： Cai Wen Rong Jiang Zhi-Qiang Zhang Bo Lei yuan-Zheng yan Ying-Quan Zhong Long Tang Department of Oral Implantology The Affiliated Stomatological Hospital of Southwest Medical UniversityLuzhou 646000Sichuan ProvinceChina Department of VIP Dental Service The Affiliated Stomatological Hospital of Southwest Medical UniversityLuzhou 646000Sichuan ProvinceChina Luzhou Key Laboratory of Oral&Maxillofacial Reconstruction and Regeneration The Affiliated Stomatological Hospital of Southwest Medical UniversityLuzhou 646000Sichuan ProvinceChina Department of Dentistry People's Hospital of Aba Tibetan and Qiang Autonomous PrefectureMa'erkang 624000Sichuan ProvinceChina Department of Radiology People's Hospital of Aba Tibetan and Qiang Autonomous PrefectureMa'erkang 624000Sichuan ProvinceChina

BACKGROUND Kissing molars(KMs)are a scarcely reported form of molar impaction in which the occlusal surfaces contact each other within a single dental follicle and the roots point in opposite *** direction of KMs impaction is generally *** with vertical direction impaction have not been reported in the *** SUMMARY A 25-year-old female visited a dentist for right maxillary wisdom teeth extraction and was diagnosed with two vertically impacted KMs in the left mandible on panoramic *** cone-beam computed tomography examination confirmed no secondary complication,the patient chose to undergo observation and regular follow-up.A literature review of KMs revealed that vertical impacted KMs are rare;high-quality evidence regarding their prevalence is still *** present,the causality of KMs is *** this study,we have tried to provide a detailed definition of KMs to allow an accurate evaluation of their prevalence and classification based on their impaction direction which may be related to their *** treatment plan of KMs depends on the condition and location of the affected teeth and associated complications;they may be either directly extracted or treated using a multidisciplinary approach including maxillofacial surgeons and *** KMs are a rare clinical condition of impacted teeth with unclear *** impacted KMs were seldom *** definition and classification of KMs can help in the understanding of their causes and prevalence.

关键词： Kissing molars Impacted tooth Pathogenesis Prevalence Classification Case report

A new approach to the synthesis of diacetals(diketals) pentaerythritol catalyzed by SO_3H-functionalized ionic liquids

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 Chemical Letters 2010年第5期21卷 524-528页

作者： yuan yuan Wang,yan Nan Xu,Zhi Zhong Wang,Li Yi Dai Shanghai Key Laboratory of Green Chemistry and Chemical Process,Department of Chemistry, East China Normal University,Shanghai 200062,China [a] Shanghai Key Laboratory of Green Chemistry Chemical Process Department of Chemistry East China Normal University Shanghai 200062 China

In this article,an efficient,simple and environmentally friendly approach to the synthesis of diacetals(diketals) pentaerythritol using SOH-functionalized ionic liquids(ILs) as catalysts was *** ILs show high catalytic activity and reusability with good to excellent yields of the desired *** method has been used to determine the acidity order of these ionic liquids and the results are consistent with the catalytic activities observed in acetalization *** product yield of 93%was observed on using[PSPy][OTf]as catalyst and it can be reused at least 8 times without obvious activity loss.

关键词： SO3H-functionalized ionic liquids Diacetals(diketals) pentaerythritol Catalyze Hammett method Reusability

Existence and Uniqueness of BV Solutions for a Class of Degenerate Boltzmann Equations with Measures as Initial Conditions

在线全文

学校读者我要写书评

暂无评论

Journal of Partial Differential Equations 2009年第2期22卷 127-152页

作者： yuan Hongjun yan Han School of Mathematics Jilin University Changchun 130012 China.

The existence and uniqueness of the solutions for the Boltzmann equations with measures as initial value are still an open problem which is posed by P. L. Lions （2000）. The aim of this paper is to discuss the Cauchy problem of the system of discrete Boltzmann equations of the formδtfi＋（fi^mi）=Qi（f1,f2...,fn）,（mi〉1,i-1,...n）with non-negative finite Radon measures as initial conditions. In particular, the existence and uniqueness of BV solutions for the above problem are obtained.

关键词： System of discrete Boltzmann equations BV solutions existence and uniqueness

A Water-soluble Conjugated Polymer for Thiol Detection Based on ＂Tu rn-off＂ Effect

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 Journal of Chemistry 2015年第8期33卷 881-887页

作者： Gaoshan Zeng Jie Li Hao Liang yan yuan Xiang Li Chao Yin Zhen yang Quli Fan Xiaomei Lu Wei Huang Key Laboratory for Organic Electronics & Information Displays and lnstitute of Advanced Materials Nanjing University of Posts & Telecommunications Nanjing Jiangsu 210046 China Jiangsu-Singapore Joint Research Center for Organic/Bio-Electronics & Information Displays and Institute of Advanced Material Nanjing Tech University Nanjing Jiangsu 211816 China

We investigated a novel water-soluble conjugated polymer （WSCP） for thiol detection based on ＂turn-off＂ ef- fect. This WSCP was modified with poly（ethylene glycol）（PEG） by disulfide linkages to achieve good solubility in aqueous solution （34 mg/mL） and high quantum yield （0.47）. The separation of water-soluble PEG chains from the conjugated backbone induced by the cleavage of the disulfide linkages would lead to a significant decrease of the water solubility and a dramatical fluorescence quenching of the probe. The combined intuitive images and fluores- cence spectrophotometer further confirmed that decreased solubility produced an aggregation of the hydrophobic conjugated backbone. The fluorescence intensity of the probe showed a good linear relationship with glutathione （GSH）（1-200 nmol·L^-1）, and the detection limit was 16 nmol·L^-1. This WSCP probe was confirmed to be a good sensing material with high selectivity to thiols by testing various biological molecules. And this WSCP probe ex- hibited good detection effect to intracellular thiols by testing Hela cells. Considering the good sensitivity and selec- tivity, the probe could be further used in vivo. In conclusion, this conjugated polymer probe made up for the draw- backs of the micromolecue probes and contributed to the development of new probes based on conjugated poly- mers.

关键词： thiols disulfide water-soluble conjugated polymer poly(ethylene glycol)