检索结果-南通市图书馆

Electrochemically Generated Iodine Cations from a Glassy Carbon Electrode for Highly Selective Iodination of Anisole

在线全文

学校读者我要写书评

暂无评论

Transactions of Tianjin University 2022年第6期28卷 433-439页

作者： Liang yan Haitao Lei Pengcheng Yang Wei Zhang Shaanxi Coal Chemical Technology Research Institute Co. LtdXi’an 710100China School of Chemistry and Chemical Engineering Shaanxi Normal UniversityXi’an 710119China

The synthesis of aryl iodides from commercially available raw chemicals by simple,cheap and green strategies is of fundamental signifi cance.Aryl iodides can undergo a series of homo-/cross-coupling reactions for the synthesis of important industrial chemicals and materials.Traditional methods require the electrophilic substitution on aromatic compounds by iodine or hypervalent iodine compounds,which suff ers from the use of erosive halogens or hazardous oxidants.With the development of green chemistry in the fi eld of electrochemical synthesis,anodic oxidation-derived I^(+)cations have been used for substitution reactions.However,the selectivity of the iodination by these electrochemical methods remains unsatisfactory.We believed that the anolyte is contaminated by trace platinum species from the working electrode.Herein,we report the generation of active I^(+)species from the anodic oxidation of I_(2) in acetonitrile using a glassy carbon electrode.With the presence of H^(+),electrolyte prepared with a glassy carbon anode can react with anisole to selectively form 4-iodoanisole with a yield as high as 97%.On contrast,the electrolytes prepared from Pt and graphite anodes fi nished the reaction with yields of 16%and 60%for 4-iodoanisole,respectively.This electrochemical method also applies to the iodination of toluene,benzonitrile and bromobenzene,delivering the target para-iodination products with 92%,84%,and 73%yields,respectively.Thus,an atom-effi cient and highly selective aryl iodination method was developed without the use of excessive oxidants.

关键词： Iodination Electrochemistry Anodic oxidation Aryl iodides Selectivity

Hierarchical hybrid testability modeling and evaluation method based on information fusion

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2015年第3期26卷 523-532页

作者： Xishan Zhang Kaoli Huang Pengcheng Yan Guangyao Lian Ordnance Engineering College Ordnance Technological Research Institute

In order to meet the demand of testability analysis and evaluation for complex equipment under a small sample test in the equipment life cycle, the hierarchical hybrid testability model- ing and evaluation method （HHTME）, which combines the testabi- lity structure model （TSM） with the testability Bayesian networks model （TBNM）, is presented. Firstly, the testability network topo- logy of complex equipment is built by using the hierarchical hybrid testability modeling method. Secondly, the prior conditional prob- ability distribution between network nodes is determined through expert experience. Then the Bayesian method is used to update the conditional probability distribution, according to history test information, virtual simulation information and similar product in- formation. Finally, the learned hierarchical hybrid testability model （HHTM） is used to estimate the testability of equipment. Compared with the results of other modeling methods, the relative deviation of the HHTM is only 0.52%, and the evaluation result is the most accu rate.

关键词： small sample complex equipment hierarchical hybrid information fusion testability modeling and evaluation.

Nanomaterials for neurodegenerative diseases:Molecular mechanisms guided design and applications

在线全文

学校读者我要写书评

暂无评论

Nano Research 2022年第4期15卷 3299-3322页

作者： Tianzhong Li Xueyan Hou Yu Qi Xiaohan Duan Pengcheng Yan Haoru Zhu Zhongjian Xie Han Zhang Shenzhen International Institute for Biomedical Research Shenzhen 518110China International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education Institute of Microscale OptoelectronicsShenzhen UniversityShenzhen 518060China School of Pharmaceutical Sciences Wenzhou Medical UniversityWenzhou 325035China Institute of Pediatrics Shenzhen Children’s HospitalShenzhen 518038China

Successful treatment of neurodegenerative diseases(NDDs),including Alzheimer’s disease(AD),Parkinson’s disease(PD),and Huntington’s disease(HD),remains a significant challenge for neurologists due to the undesirable curative outcomes.Apart from surgeries,most drugs are only used to relieve the patients’symptoms without a permanent cure of the disease.The development of novel biomaterials targeting NDDs is greatly hindered by the limited understanding of underlying molecular mechanisms.Considering the difficulties in NDD drug development and clinical trials,a comprehensive and up-to-date review of disease pathogenesis and related novel therapies are needed.In the current article,the basic concepts and pathogenic characteristics of NDDs are firstly illustrated.Following the detailed description of molecular mechanisms underlying three common NDDs,recent advances of drug development based on targeting different pathogenic mechanisms are clarified.Hopefully,this review will be beneficial to address the gap between materials and targeted mechanisms while simultaneously provide suggestions for the future design of precise NDD medicine.

关键词： neurodegenerative diseases molecular mechanisms nanomaterials signaling pathways protein aggregation

Theoretical Study on the Structures,Spectral Properties,and Drugability of Xenicane-type Diterpenoids from Dictyota dichotoma

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2022年第2期38卷 622-631页

作者： HUANG Luoyi SUN Xiang CHEN Mengyi yan pengcheng WANG Chaojie School of Pharmaceutical Sciences Wenzhou Medical UniversityWenzhou 325035P.R.China Department of Pharmacy The First Affiliated Hospital of Wenzhou Medical UniversityWenzhou 325000P.R.China

There are few reports on the relationship between the biological activity and structure of secondary metabolites from Dictyota dichotoma. In this work, the geometric and electronic structures, infrared spectra, ultraviolet spectra, 13C and 1H NMR spectra of 16 xenicane-type diterpenoids extracted from Dictyota dichotoma were studied by the density functional theory ωB97XD/6-311+G(2d,p) method. The analysis of the reactivity indices was carried out via the conceptual density functional theory. Furthermore, a pharmacodynamic evaluation was performed using ADME/Tox. The geometric structure analysis found that all 16 diterpenoids had the same unsaturated, branched chains and could be divided into two categories according to the ring size, including nine-membered and eight-membered rings. A hydroxyl group on the lactone ring reduced the stability of the compound. In contrast, a hydroxyl group on the parent ring had little effect on the compound's stability. The electrostatic potential results preliminarily predicted active sites for nucleophilic/electrophilic reactions. The fitting results of infrared and nuclear magnetic resonance(NMR) data showed that the theoretical values obtained by this method were consistent with the experimental values. The UV-visible absorption spectra showed that the solvent effects caused different redshifts of the absorption peaks. The absorption strength was enhanced. The sixteen diterpenoids displayed a strong absorption peak in the range of 180―200 nm, but the compound containing a carbonyl group presents a weaker absorption peak in the field of 200―240 nm. Compounds 9―11, 14, and 15 have better stability and reactivity with lower chemical potentials and higher electronegativity, electrophilic index, and hardness values. The local reactivity descriptors further identified nucleophilic/electrophilic reaction sites for the sixteen compounds. Finally, the pharmacodynamic evaluation results predicted that compounds 2, 4, 8, 11, and 14―16 have optimal drugability. The theoretical results of

关键词： Dictyota dichotoma Diterpenoid Conceptual density functional theory

Carbon nanotubes decorated FeNi/nitrogen-doped carbon composites for lightweight and broadband electromagnetic wave absorption

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 Materials Science & Technology 2023年第27期158卷 207-217页

作者： Juhua Luo Wenxing yan Xiaopeng Li pengcheng Shu Jie Mei Yafan Shi School of Materials Science and Engineering Yancheng Institute of TechnologyYancheng 224051China Jiangsu Provincial Key Laboratory of Eco-Environmental Materials Yancheng Institute of TechnologyYancheng 224051China

Magnetic-dielectric component modulation and heterogeneous interface engineering were considered as an effective strategy for designing lightweight and broadband electromagnetic wave(EMW)absorbors.Herein,a series of carbon nanotubes(CNTs)decorated core-shell nitrogen-doped carbon(CNTs/FeNi/NC)composites were successfully fabricated via the carbonization of CNTs/NiFe_(2)O_(4)/PDA precursors obtained by hydrothermal and polymerization method.The EMW absorption(EMWA)properties of CNTs/FeNi/NC composites were explored by varying the CNTs content.When the CNTs content was 15%,the minimum reflection loss(RL_(min))value was-51.13 dB at 9.52 GHz and the corresponding effective absorption band-width(EAB)value was 2.96 GHz(8.96-11.12 GHz)at 2.5 mm.Particularly,the maximum EAB value can reach up to 4.64 GHz(12.80-17.44 GHz)at 1.7 mm.The excellent EMW attenuation capability resulted from the enhanced conductive loss,polarization loss,magnetic loss,and improved impedance matching.This work offers a novel reference for designing lightweight and broadband EMWA materials.

关键词： Carbon nanotubes Nano-heterogeneous interface engineering Electromagnetic wave absorption Impedance matching

1D/2D CoTe_(2)@MoS_(2)composites constructed by CoTe_(2)nanorods and MoS_(2)nanosheets for efficient electromagnetic wave absorption

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2023年第7期16卷 10698-10706页

作者： Naixin Zhai Juhua Luo pengcheng Shu Jie Mei Xiaopeng Li Wenxing yan School of Materials Science and Engineering Yancheng Institute of TechnologyYancheng 224051China Jiangsu Provincial Key Laboratory of Eco-Environmental Materials Yancheng Institute of TechnologyYancheng 224051China

Rational design of the components and microstructure is regarded as an efficacious strategy for the high-performance electromagnetic wave absorbing(EMWA)materials.Herein,the CoTe_(2)@MoS_(2)nanocomposites with CoTe_(2)nanorods and MoS_(2)nanosheets were synthesized via a hydrothermal method.The microstructure and composition of the samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy(XPS).The CoTe_(2)@MoS_(2)composite was composed of stacked CoTe_(2)as the core and intertwined MoS_(2)nanosheets as the shell.The electromagnetic parameters of the CoTe_(2)@MoS_(2)composites were investigated by vector network analyzer(VNA).The EMWA property of the composite showed a trend of first increasing and then decreasing with the increasing content of MoS_(2).When the mass ratio of MoS_(2)and CoTe_(2)was 1:1,the CoTe_(2)@MoS_(2)composite exhibited the minimum reflection loss value of-68.10 dB at 4.71 GHz,and the effective absorption bandwidth value might reach 4.64 GHz(13.08-17.72 GHz)at a matching thickness of 1.60 mm with filler loading of 50 wt.%.The extraordinary EMWA property was attributed to the optimized impedance matching,multiple scattering and reflections,dipole polarization,conductive loss,and interfacial polarization.Therefore,the present approach to the design of microstructure and interface engineering offers a crucial way to construct high-performance EMW absorbers.

关键词： transition metal tellurides microstructure design heterostructure engineering electromagnetic wave absorption

Generalized fiducial methods for testing quantitative trait locus effects in genetic backcross studies

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Statistical Theory and Related Fields 2022年第2期6卷 148-160页

作者： pengcheng Ren Guanfu Liu Xiaolong Pu yan Li KLATASDS-MOE School of StatisticsEast China Normal UniversityShanghaiPeople’s Republic of China School of Statistics and Information Shanghai University of International Business and EconomicsShanghaiPeople’s Republic of China

In this paper,we propose generalized fiducial methods and construct four generalized p-values to test the existence of quantitative trait locus effects under phenotype distributions from a location-scale family.Compared with the likelihood ratio test based on simulation studies,our methods perform better at controlling type I errors while retaining comparable power in cases with small or moderate sample sizes.The four generalized fiducial methods support varied sce-narios:two of them are more aggressive and powerful,whereas the other two appear more conservative and robust.A real data example involving mouse blood pressure is used to illustrate our proposed methods.

关键词： Generalized fiducial inference quantitative trait locus mixture model Gibbs algorithm likelihood ratio test

Exploitation of a photoelectrochemical sensing platform for bisphenol A quantitative determination using Cu/graphitic carbon nitride nanocomposites

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 2018年第11期29卷 1629-1632页

作者： Sheng Feng Pengcheng Yan Li Xu Jiexiang Xia Huaming Li School of Environmental and Safety Engineering Changzhou University Institute for Energy Research School of Chemistry and Chemical EngineeringJiangsu University

A simple and effective photoelectrochemical sensor was fabricated by Cu/graphitic carbon nitride （Cu/g- CN） composites for detecting bisphenol A. The Cu/g-CN composites were obtained via a solvothermal process in the presence of the copper-based ionic liquid. In view of localized surface plasmon resonance ofCu nanoparticles, Cu nanoparticles can promote light absorbance and rapid electron transport ofg-CN. As a result, the Cu/g-CN composites obtained greatly enhancement of photocurrent, when compared to the pure g-CN. In addition, the introduction of bisphenol A can hinder electron-hole recombination, resulting in sensitive photoelectrochemical monitoring of bisphenol A. The detection limit of the bisphenol A photoelectrochemical sensor was below 0.012 μmol/L. The bisphenol A photoelectrochemical sensor exhibited an excellent stability and acceptable anti-interference. The photoelectrochemical sensor provided the promising platform to monitor bisphenol A at low concentration in water environment.

关键词： Photoelectrochemical detection Graphitic carbon nitride Cu nanoparticles Bisphenol A Localized surface plasmon resonance

Modification strategies on transition metal-based electrocatalysts for efficient water splitting

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2021年第7期30卷 446-462页

作者： Yaotian yan pengcheng Wang Jinghuang Lin Jian Cao Junlei Qi State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001HeilongjiangChina School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001HeilongjiangChina

Electrocatalytic water splitting driven by electrocatalysts is recognized as a promising strategy to generate clean hydrogen fuel.Searching and constructing high-efficient and low-cost electrocatalysts is vital in the practical applications of electrocatalytic water splitting.Although transition metal-based materials have been considered as promising electrocatalysts,the satisfactory activities are usually not built on the bulk materials,but strongly relying on elaborately designing these electrocatalysts.Herein,the recent theoretical and experimental progress on modification strategies to improve the intrinsic activities is summarized,especially including element doping,phase engineering,structure cooperation,interface engineering,vacancy engineering,strain engineering and self-functionalization.Finally,the future opportunities and challenges on these modification strategies are also proposed.Overall,it is anticipated that these modification strategies offer some new understandings on rationally constructing non-noble electrocatalysts for efficient electrocatalytic water splitting.

关键词： Electrocatalysts Modification Intrinsic activity Active sites Transition metal