Overview of the detection methods for equilibrium dissociation constant KD of drug-receptor interaction

Drug-receptor interaction plays an important role in a series of biological effects, such as cell pro- liferation, immune response, tumor metastasis, and drug delivery. Therefore, the research on drug-re- ceptor interaction is growing rapidly. The equilibrium dissociation constant （KD） is the basic parameter to evaluate the binding property of the drug-receptor. Thus, a variety of analytical methods have been established to determine the KD values, including radioligand binding assay, surface plasmon resonance method, fluorescence energy resonance transfer method, affinity chromatography, and isothermal ti- tration calorimetry. With the invention and innovation of new technology and analysis method, there is a deep exploration and comprehension about drug-receptor interaction. This review discusses the differ- ent methods of determining the KD values, and analyzes the applicability and the characteristic of each analytical method. Conclusively, the aim is to provide the guidance for researchers to utilize the most appropriate analytical tool to determine the KD values.

Mobile Equilibrium Method for Determining Composition and Stability Constant of Coordination Compounds of the Form M_mR_n

A new method is proposed for determining the composition and stability constant of coordination compounds of the form M m R n ; it can be used to differentiate mono and poly nuclear coordination compounds. The equation derived is lg( A i/(A max - A i) m)=n lg c′ R+lg( m·β(c M/A max ) ( m -1) ). The method is based on Bent French limited logarithm method. The demonstration of the proposed method has yielded correct results for Sc 3+ chlorophosphonazo Ⅲ system and Fe 3+ Chromazurol S system.

On an Expression of Extraction Constants without the Interfacial Equilibrium-Potential Differences for the Extraction of Univalent and Divalent Metal Picrates by Crown Ethers into 1,2-Dichloroethane and Nitrobenzene

An idea on interfacial equilibrium-potential differences () which are generated for the extraction of univalent metal picrate (MPic) and divalent ones (MPic2) by crown ethers (L) into high-polar diluents was improved. These potentials were clarified with some experimental extraction-data reported before on the M = Ag(I), Ca(II), Sr(II) and Ba(II) extraction with 18-crown-6 ether (18C6) and benzo-18C6 into 1,2-dichloroethane (DCE) and nitrobenzene (NB). Consequently, it was demonstrated that the? values from the extraction-experimentally obtained logKD,Pic ones are in agreement with or close to those calculated from charge balance equations in many cases, where the symbol, KD,Pic, denotes an individual distribution constant of Pic﹣ into the DCE or NB phase. Also, it was experimentally shown that extraction constants based on the overall extraction equilibria do not virtually contain the? terms in their functional expressions.

Thermodynamic model for equilibrium solubility of gibbsite in concentrated NaOH solutions

The thermodynamic properties of the most important NaOH-NaAI（OH）4-H20 system in Bayer process for alumina production were investigated. A theoretical model for calculating the equilibrium constant of gibbsite dissolved in sodium hydroxide solution was proposed. New Pitzer model parameters and mixing parameters for the system NaOH-NaAI（OH）4-H20 were yielded and tested in the temperature range of 298.15-373.15 K. The results show that the proposed model for calculating the equilibrium constant of gibbsite dissolution is applicable and accurate. The obtained Pitzer model parameters of β（0）（NaAl（OH）4）、β（1）（NaAl（OH）4）和CΦ（NaAl（OH）4）,Al（OH）4 for NaAI（OH）4, the binary mixing parameter of θ（OH-Al（OH）4-） with OH-, and the ternary mixing parameter of ψ（Na＋OH-Al（OH）4-） for AI（OH）4- with OH- and Na＋ are temperature-dependent. The prediction of the equilibrium solubility of gibbsite dissolved in sodium hydroxide solution was feasible in the temperature range of 298.15-373.15 K.

Thermal Analysis of Thermophysical Data for Equilibrium Pure Fluids

The thermal analysis of precise thermophysical data for pure fluids from electronic databases is developed to investigate the molecular interaction mechanisms and parameters and the structural features of heterogeneities in fluids. The method is based on the series expansion of thermophysical values by powers of the monomer fraction density. Unlike the virial expansion by powers of the total density, the series expansion terms in this method directly reflect properties of the corresponding cluster fractions. The internal energy had been selected among thermophysical properties as the most informative for this method. The thermal analysis of its series expansion coefficients permits to estimate the temperature dependence of the pair bond parameters, the clusters’ bond energies and equilibrium constants, the structural transitions between dominating isomers of clusters. The application of method to different pure fluids, including noble and molecular gases with van der Waals and polar molecular interactions, brings unknown clusters’ characteristics for the fluids under investigation. The thermal analysis of the ordinary and heavy Water vapors points on no trivial isotopic effects. The unpredictable growth of the pair bond energy with temperature in Alkanes points on existence in hydrocarbons of some unknown molecular interaction forces in addition to dispersion forces.

EQUILIBRIUM OF Mg-S IN Ni MELTS

The equilibrium of Mg-S in Ni melt was studied by the method of vapour equilibrium in a sealed chamber.At 1530℃ the equilibrium constant of the reaction MgS_(s)=Mg_(Ni)+S_(Ni)and the activity interaction coefficient were determined as K_(MgS)=6.76×10^(-5)and e_S^(Mg)=-9.1.

Equilibrium Thermal Physics of Noble Gases

The aim of this research is to apply the author’s original computer aided analysis of thermophysical data for pure fluids to noble gases to investigate the unknown aspects in their equilibrium thermal physics. The methodology of the analysis is based on the potential energy density series expansion by the monomer fraction density. To discover the important details and particular features of pair atomic interactions in noble gases, the preprocessed and generalized experimental data have been taken from the US National Institute of Standards and Technology (NIST) online database. In this work the temperature range for analysis of the dimers’ bonding parameters is extended as compared to previous author’s works due to accounting for the specific temperature dependence of the repulsions’ contribution to the potential energy. The found temperature dependences of the pair interaction bond energies signal about the hindered rotation of atoms in dimers near the triple point due to the lack of rotational symmetry of their electronic outer shells. The discovered mutually correlated anomalous temperature dependences of the pair bond energy and the constant volume heat capacity in gaseous Helium require a special investigation of this remarkable phenomenon.

浮选固液系统的热力学理论及应用

浮选是发生在固液界面的物理化学行为,涉及多种物质组分之间的相互作用,是浮选理论研究的难题之一。同时,多种浮选药剂联合使用,提高矿物的浮选效果,是提高难处理矿产资源高效利用的有效手段。但对浮选固液复杂系统的研究极其困难,至今没有形成系统的理论,组合药剂提高浮选效果的物理机制也还没有获得统一的认识,这都限制了浮选理论的发展和浮选技术的进步。基于热力学基本方程,研究了浮选过程中药剂在矿物表面吸附的熵变和吉布斯自由能变化,构建了各种物质组分相互作用的热力学平衡方程组,提出了反映浮选药剂在矿物表面吸附能力的吸附平衡常数。应用浮选热力学平衡方程组,揭示浮选中各种矿物表面同质化效应的物理本质,推导出了浮选溶度积理论、双电层理论、吸附理论的数学表达式。建立了通过增加矿物表面吸附浮选药剂种类,提高浮选药剂的吸附熵变,减少吉布斯自由能变化,提高浮选药剂吸附的效率和稳定性,从而提高难处理矿物的浮选效果的高熵浮选理论和技术方法。

Geometrical structures, vibrational frequencies, force constants and dissociation energies of isotopic water molecules (H_2O, HDO, D_2O, HTO, DTO, and T_2O) under dipole electric field

The dissociation limits of isotopic water molecules are derived for the ground state. The equilibrium geometries, the vibrational frequencies, the force constants and the dissociation energies for the ground states of all isotopic water molecules under the dipole electric fields from -0.05 a.u. to 0.05 a.u. are calculated using B3P86/6-311＋＋G（3df,3pf）. The results show that when the dipole electric fields change from -0.05 a.u. to 0.05 a.u., the bond length of H-O increases whereas the bond angle of H-O H decreases because of the charge transfer induced by the applied dipole electric field. The vibrational frequencies and the force constants of isotopic water molecules change under the influence of the strong external torque. The dissociation energies increase when the dipole electric fields change from -0.05 a.u. to 0.05 a.u. and the increased dissociation energies are in the order of H2O, HDO, HTO, D2O, DTO, and T2O under the same external electric fields.

Density of Vacuum-Like Plasma and Hubble Constant

The model in which expansion of the Universe leads to a generation of non-equilibrium vacuum-like electron-positron plasma is proposed and researched. The formulas that relate the Hubble’s constant with the concentration of plasma particles and the cosmological constant are obtained. The collective properties of vacuum-like plasma are investigated. It is shown, that the coefficient of a two-photon annihilation in such plasma is nine times less than for the free particles. A simple formula for dark energy density as a function of electron mass and charge is obtained. It was demonstrated that acceleration of plasma’s chemical potential fluctuations flow proportional of dark energy density.

一类含常数项的混沌系统在未知参数下的同步

研究了一个新的含有常数项的混沌系统在参数未知情况下的修正函数投影同步问题。对新的含有常数项的混沌系统从平衡点的稳定性、耗散性、poincare映射、功率谱及初值敏感性5个方面进行了特性分析。基于修正函数投影同步方法,设计了有效的控制输入及参数自适应律,根据Lyapunov函数稳定性定理从理论上证明修正函数投影同步误差系统在原点的渐近稳定性,从而实现了新混沌系统的修正函数投影同步控制。数值模拟仿真证明了同步方法的正确性,该同步方法可以应用于混沌保密通信的研究中。

Persistence in a Stochastic SEIR Model with Constant Immigration in Incubation Period

A kind of stochastic susceptible-exposed but not infectiousinfectious-removed (SEIR) model with constant immigration in incubation period is presented, based on a deterministic SEIR model, via the technique of parameter perturbation which is standard in stochastic population modeling. The influence of the environmental noise as a standard Gaussian white noise on the epidemics' transmission is studied. Furthermore,the condition for the epidemics' persistence is obtained by formulating the corresponding function and using It 's formula. And the asymptotic behavior of the model near the endemic disease equilibrium is also studied. In this way, the decision support is provided in the application of this kind of stochastic SEIR model on the epidemics' prevention and control.

氨合成塔操作线与平衡线的在线可视化模块开发

在选择吉布斯反应器的基础上,根据某专利商提供的三床层氨合成塔相关数据,修正了UniSim流程模拟软件数据库中氨的标准摩尔生成吉布斯自由能。结合某150 kt/a氨合成塔实际生产工艺和集散控制系统(DCS)采集的现场生产数据,采用OPC通讯协议,实时更新UniSim的动态输入数据,构建了“生产数据驱动+机理模型”的数字孪生方法,达到了计算结果与生产数据的高度吻合;通过构建在线合成氨动态操作线和平衡线,实现了氨合成塔的在线评价,为即时操作决策和实时优化提供了数字化依据。

乙烯基醚系列产品合成过程的热力学研究

乙烯基醚是一类重要的聚合单体,但针对其合成过程的系统热力学分析尚未见报道。分别采用Benson法、Joback法等方法,以经典热力学公式为基础,计算了乙炔与不同醇(甲醇、乙醇、丁醇、异丁醇以及叔丁醇)合成对应乙烯基醚类化合物(乙烯基甲醚、乙烯基乙醚、乙烯基丁醚、乙烯基异丁醚以及乙烯基叔丁醚)的热力学参数,包括在反应温度为283~363 K下的焓变(△_(r) H^(θ))、熵变(△_(r) S^(θ))、吉布斯自由能(△_(r) G^(θ))和反应平衡常数(K)。系统分析和总结了不同结构的醇与乙炔发生亲核加成反应过程的难易程度,以及热力学反应参数的变化规律。结果表明,所有反应均为强放热反应且均可自发进行,反应温度越低反应进行得越彻底。即使在近室温(283 K)条件下,乙烯基醚类化合物仍可顺利合成,且反应温度越低,安全性越高。本研究结果可为乙烯基醚工业化生产提供理论指导。

多相体系的酸碱解离平衡:气相的影响

酸碱平衡是化学教学中十分重要的内容,而在目前的教学中仅仅描述了均相溶液中的酸碱解离与pH缓冲问题,并未描述多相体系中气相成分对体系酸碱解离与pH缓冲的影响。针对该问题,本文以典型的气溶胶多相体系为例,通过对多相缓冲理论和有效解离常数pK_(a)^(*)的分析,讨论了多相体系中组分挥发性和吸湿性对体系酸碱平衡的影响,进而开拓学生思维,并为多相体系酸碱平衡的教学提供新范例。

第52届国际物理奥林匹克竞赛理论第2题介绍与解答

第52届国际物理奥林匹克竞赛理论部分共三道题目,本文主要对理论第二题“詹姆斯·韦伯太空望远镜”题目进行介绍,给出参考解答以及对中国学生答题情况的分析。

一种具有超级多稳态的忆阻混沌系统及其在电力图像加密中的应用

混沌系统的构造和图像加密是相互联系、相互独立的研究方向,同时也是当前混沌系统的研究热点。在Sprott-I混沌系统中引入绝对值忆阻器,构造了一个新的忆阻混沌系统。受忆阻器强非线性的影响,新系统的平衡点变为了一条线平衡点集,表现出了更丰富的动力学特性。通过MATLAB仿真分析了该系统的Lyapunov指数、耗散性、分岔图等动力学特征,结果表明新系统不但能产生依赖系统参数变化的混沌吸引子和周期极限环的常规现象,而且能够产生恒Lyapunov指数以及依赖于初始条件变化的分岔图偏移以及无限多吸引子共存的超级多稳态的特殊动力学现象。最后,考虑到系统在引入忆阻器后出现的超级多稳态现象,能够产生鲁棒性更好的伪随机序列,因此将该系统和DNA编码结合引入到电力图像加密中,在MATLAB平台上进行安全分析实验结果表明,该算法具有良好的加密效果。

热力学计算在水离子积常数与难溶物溶度积的教学中应用

加强知识点之间的内在联系不仅能提高教学效果,还能培养学生的科学思维能力。本文将从化学反应基本原理入手,利用相关物质的热力学性质(焓、熵和吉布斯自由能)计算水离子常数与难溶物溶度积,并得到相关的计算值;然后结合计算值与参考值之间对比分所得的相对误差以验证二者之间的关联性,以期充分挖掘化学专业课程中知识点之间的逻辑连贯性并体现出化学的科学性。

氨法脱硫反应特性的化学动力学分析

对采用氨法脱除烟气中SO2过程的反应特性进行了热力学和动力学分析.结果显示,氨法脱硫反应活化能较低,只要温度控制适当,氨法脱硫具有很高的平衡常数(或转化率)和良好的动力学特性.同时,根据实验结果拟合整理出了实验温度范围内氨法脱硫反应的Arrhenius方程,分析了温度对氨法脱硫反应速率的具体影响.

甲醇制低碳烯烃(MTO)反应热力学研究

对甲醇制低碳烯烃反应过程进行了热力学分析。着重计算了甲醇制烯烃主副反应的反应热、吉布斯自由能、平衡常数以及烯烃产物之间的平衡关系等。甲醇制烯烃大多数反应为强放热反应,总反应热在37～53kJ/mol之间,而且大多数反应都可以自发进行,并进行到很高的程度。通过烯烃产物之间平衡关系的计算,发现计算结果与实际的甲醇制烯烃反应现象比较一致,随着反应温度的升高,乙烯平衡摩尔分数持续增大,丁烯平衡摩尔分数持续下降,而丙烯摩尔分数则先升后降。烯烃产物之间的相互转化属于热力学平衡限制。