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Quick estimation of the D_(pb) for predicting the strength of chemical bond in situ

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Chinese Chemical Letters 2013年第10期24卷 912-916页

作者： xia Du dong-xia zhao Zhong-Zhi Yang Chemistry and Chemical Engineering Faculty Liaoning Normal University

An approximate method has been established to calculate the depth of the potential acting on an electron in a molecule at the saddle point along a chemical bond, denoted by Dpb. It is a new indicator which can be used for predicting the strength of a chemical bond. In this work, as a practical application for demonstrating this method, we calculated the Dpb of deoxyribonucleosides and ribonucleosides along all C-H and N-H chemical bonds using the method. The results are in fair agreement with those results of previously reported experimental and theoretical observations,

关键词： Bond strength Dpb Deoxyribouncleosides Ribonucleosides

Theoretical Investigation on Regioselectivities of Diels-Alder Reactions by Conjugated Effect

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Chinese Journal of Chemistry 2020年第12期38卷 1696-1702页

作者： Zhen-Zhen Xu Jian zhao dong-xia zhao Zhong-Zhi Yang Jiangxi Province Key Laboratory of the Causes and Control of Atmospheric Pollution and School of Chemistry Biology and Materials ScienceEast China University of TechnologyNonchangJiangxi 330013China School of Chemistry and Chemical Engineering Liaoning Normal UniversityDalianLiaoning 116029China

of main observation and conclusion The regioselectivities of 76 Diels-Alder reactions between unsymmetrical dienes and dienophiles were investigated by local softness and generalized local softness at atomic and chemical bond view,respectively,where the reactivity descriptors were calculated by finite difference approximation and ABEEMan *** on local HSAB principle and matching criterion of local softness,reasonable explanation and prediction on regioselectivities of all reactions through ABEEMan model have been obtained,which are in agreement with the experimental ***,at n-bond level,while the 1-substituents of dienes were NH2/NMe2,and NEt2/because of the p-R conjugated effect between the lone pairs of Natom and the conjugated n-bond of the four double-bonded carbon atoms in diene,it made the dienophile not easy to approach diene by Manner A,hence,Manner B can forecast the ortho regioisomer as main product well,and Manner A *** to the other reactions,both Manner A and Manner B can predict their *** can be seen that the ABEEMan model can take the effect of the chemical environment on the reaction reactivity into account richly,especially the system includes n-bond and lone ***,the results through the finite difference approximation are not reasonable.

关键词： reactivity conjugated approximation

Rationalization of regioselectivity of electrophilic substitution reaction for cyclic compounds in terms of D_(pb) values

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Chinese Chemical Letters 2015年第5期26卷 553-556页

作者： Yang Liu Zhong-Zhi Yang dong-xia zhao School of Chemistry and Chemical Engineering Liaoning Normal University

Accepted theories predict that substitution reactions are controlled by the electronic nature of the attacked site for electrophilic aromatic substitution. Here it is shown that in addition the bond strength of the broken bond may also influence the regioselectivity of the substitution reaction, and that the Dpb is a good indicator of the strength of a chemical bond. The Dpb denotes the depth of the potential acting on one electron in a molecule at the bond center （bc）. In this letter, the values of Dpb along the C-H and N-H bonds have been investigated, and it is demonstrated that for aromatic compounds, the regioselectivity of the electrophilic substitution can well be rationalized in terms of Dpb values.

关键词： Dpb Substitution reaction Regioselectivity Bond strength

An investigation of crambin and BPTI based on ABEEM/MM model

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Chinese Chemical Letters 2007年第12期18卷 1554-1556页

作者： Qing Mei Guan dong xia zhao Zhong Zhi Yang Department of Chemistry Liaoning Normal University Dalian 116029 China

Molecular dynamics simulation studies on crambin, BPTI （298 K, in vacuo） have been performed by ABEEM/MM method. Some structural properties were discussed. The results show fair consistency with those from X-ray exp... 详细信息

关键词： ABEEM/MM method Crambin BPTI Molecular dynamics simulations

Theoretical investigation of the stereoselectivity of some Diels-Alder reactions involving cyclopentadiene

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Chinese Chemical Letters 2008年第9期19卷 1135-1138页

作者： dong xia zhao Zhen Zhen Xu Zhong Zhi Yang College of Chemistry and Chemical Engineering Liaoning Normal University Dalian 116029 China

The stereoselectivity of some Diels-Alder reactions was investigated by means of ABEEM-oTr model. Combined with local hard-soft and acid-base （HSAB） principle, we made reasonable explanation by calculating local sof... 详细信息

关键词： ABEEM-σπ model Diels--Alder reaction Stereoselectivity Local softness

溪黄草浸提液对2种杂草种子萌发和幼苗生长的化感作用

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草地学报 2024年第7期32卷 2118-2127页

作者：陈幻真许明爽周天宇黄燕丽李超董朝霞华南农业大学南方草业中心广东广州510642

为研究溪黄草(Rabdosia serra(Maxim.)Hara)浸提液对杂草种子萌发与幼苗生长的化感作用,本试验以稗草(Echinochloa crusgalli L.)和马唐(Digitaria sanguinalis L.)为受体材料,采用培养皿滤纸法测定了稗草与马唐的种子萌发、幼苗形态和... 详细信息

为研究溪黄草(Rabdosia serra(Maxim.)Hara)浸提液对杂草种子萌发与幼苗生长的化感作用,本试验以稗草(Echinochloa crusgalli L.)和马唐(Digitaria sanguinalis L.)为受体材料,采用培养皿滤纸法测定了稗草与马唐的种子萌发、幼苗形态和生理指标。结果表明:(1)溪黄草鲜样浸提液在80 mg·mL^(-1)时,对马唐与稗草种子的萌发和根长起到显著的抑制作用(P<0.05);(2)随着溪黄草干样和鲜样浸提液浓度的升高,稗草的过氧化物酶(Peroxidase,POD)和过氧化氢酶(Catalase,CAT)活性显著升高,而马唐的POD和CAT活性则显著降低(P<0.05);(3)当溪黄草干样和鲜样浸提液浓度为20,40,80 mg·mL^(-1)时,对马唐的化感综合效应表现为抑制作用,且浸提液浓度越高抑制作用越强。综上所述,溪黄草浸提液在浓度为80 mg·mL^(-1)时,对马唐种子萌发和幼苗生长具有显著的抑制作用(P<0.05)。

关键词：溪黄草马唐稗草浸提液化感作用

Exponential Stability of a Coupled Heat-ODE System 25th

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Exponential Stability of a Coupled Heat-ODE System

Experimental study on asphaltene precipitation induced by CO_2 flooding

第25届中国控制与决策会议

作者： dong-xia zhao Jun-Min Wang the Department of Mathematics Beijing Institute of Technology the Department of Mathematics North University of China the Department of Mathematics Beijing Institute of Technology

ISBN: (纸本)9781467355339

This paper addresses the feedback stabilization of an interconnected Heat-ODE system with the Dirichlet interconnection. The "interconnection" between the heat equation and the ODE are bi-directional, in which the Dirichlet boundary observation of the heat equation is fed into the ODE, and the velocity of ODE is flowed into the boundary of the heat equation. The semigroup approach is adopted in investigation. By a detailed analysis, we obtain the asymptotic expressions of eigenvalues and eigenfunctions. It is shown that there is a sequence of generalized eigenfunctions, which forms a Riesz basis for the Hilbert state space. This deduces the spectrumdetermined growth condition for the C0-semigroup, and as a consequence, the exponential stability of the system is then followed. Numerical simulations are presented.

关键词： Heat equation Dirichlet interconnection Riesz basis Exponential stability

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Petroleum Science 2014年第1期11卷 174-180页

作者： dong zhao-xia WANG Jun LIU Gang LIN Mei-qin LI Ming-yuan Enhanced Oil Recovery Research Institute China University of Petroleum Beijing Key Laboratory for Greenhouse Gas Storage and Enhanced Oil Recovery Key Laboratory of Enhanced Oil Recovery CNPC

The effects of CO2 pressure,temperature and concentration on asphaltene precipitation induced by CO2 were studied using a high-pressure vessel,interfacial tensiometer,Fourier transform infrared （FTIR） and drill core displacement experimental *** results indicated that the content of asphaltene in crude oil decreased,and the interfacial tension between a model oil and distilled water increased,with an increase of CO2 pressure,decrease of temperature and increase of molar ratio of CO2 to crude oil when CO2 contacted crude oil in the high pressure *** content of asphaltene in sweepout oil and the permeability of test cores both also decreased with an increase of CO2 flooding *** main reason for changes in content of asphaltene in crude oil,in interfacial tension between model oil and distilled water and in the permeability of the test core is the precipitation of asphaltene which is an interfacially active substance in crude *** of asphaltene also blocks pores in the drill core which decreases the permeability.

关键词： CO2 flooding asphaltene precipitation oil-water interfacial tension core permeability

Influence of dissolved oxygen content on oxidative stability of linked polymer solution

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Petroleum Science 2009年第4期6卷 421-425页

作者： zhao-xia dong Mei-qin Lin Jian Xin Ming-yuan Li China Univ Petr Enhanced Oil Recovery Res Ctr Beijing 102249 Peoples R China

The influence of dissolved oxygen content on the oxidative stability of a linked polymer solution (LPS) was studied by micro-filtration, dynamic light scattering and viscosity measurements. The results showed that at the same temperature, the degree of the oxidative degradation of the LPS increased and the rapidity of the oxidative degradation was accelerated with the increase of the dissolved oxygen content. Consequently, the size of linked polymer coils (LPCs) of the LPS became small, and the plugging capability of the LPS decreased. At a fixed content of dissolved oxygen, with increasing degradation temperature, almost the same results were observed, namely, an increased degree of oxidative degradation, accelerated rapidity of the oxidative degradation and decreased plugging capacity, with decreased oxidative stability of LPS. At 90 °C, in the presence of oxygen, LPS lost its plugging capability after having been degraded for a period of time. But at 40 °C, LPS with low dissolved oxygen content could be stable for a long time. The decreased plugging ability of LPS after oxidative degradation is mainly caused by the decreased size and number of the LPCs due to the breaking of hydrolyzed polyacrylamide (HPAM) molecule segments and the structural changing of HPAM molecules.

关键词： Linked polymer solution HPAM content of dissolved oxygen degradation stability