A thermodynamic approach with internal variables using Lagrange formalism. Part I: General framework

We present some reflections on the application of the Lagrangian formalism for continuous media locally uniform subjected to internal irreversible evolutions. The Lagrangian density, defined as the time derivative of a non-equilibrium thermodynamic potential, [Thermodynamics of Relaxation Processes using Internal variables within a Lagrange-formalism. P. Germain’s Anniversary Volume 2000. Contiuum Thermomechanics: the Art and Science of Modeling Matter’s Behaviour, 2000], contains all the symmetry properties of the system. The generalised Lagrange co-ordinates correspond to the state and internal variables of the time derivative of the generalised Gibbs potential. The latter being used within the framework of the De Donder’s method, must also account for the memory effect of the physical medium.This first part is devoted to the thermodynamic framework called the distribution of non-linear relaxations approach (DNLR) developed by C. Cunat on the basis of the generalised Gibbs’ relation.     

磁性多壁碳纳米管吸附水中双氯芬酸的热力学与动力学

研究了磁化多壁碳纳米管(MWCNTs)对于水中非甾体抗炎药双氯芬酸的吸附过程.结果表明,双氯芬酸的吸附量随磁性MWCNTs投加量的增加而增大,而且吸附剂量增加到一定阶段后,双氯芬酸的吸附量达到平衡.在磁性MWCNTs的量为0.7g·L-1时,水溶液中双氯芬酸被磁性MWCNTs吸附的量达到最大,为33.37mg·g-1,对应的双氯芬酸去除率为98.1%.双氯芬酸的去除率随溶液pH的增加先增大后下降,随温度的升高而下降.用准一级、准二级模型进行了动力学分析.回归结果表明,准二级模型更准确地反映了吸附动力学.通过实验确定了Langmuir和Freundlich等温线的线性相关系数与标准偏差,结果揭示出Langmuir等温线与实验数据有很好的拟合度.对热力学参数的计算表明,ΔG00,意味着磁性MWCNTs对双氯芬酸的吸附是自发的;ΔH00,指明吸附是一个放热的物理吸附过程,温度低对吸附有利;ΔS00,代表该吸附是熵增过程.     

Thermodynamic mixing properties of liquids in the system Na2O-SiO2

Enthalpies of fusion have been measured by differential scanning calorimetry for a Na₂O-SiO₂ system at 50, 66.6, and 74.4 mol% SiO₂. Enthalpies of mixing of liquids obtained from different calorimetry techniques are critically evaluated. The data on calorimetric enthalpy, activity of Na₂O, cristobalite liquidus, and immiscibility gap are used to determine the enthalpy and entropy of mixing of sodium-silicate liquids are determined as a function of composition by the least squares method. The derived mixing properties are based only on the experimental data and are independent of any assumption about the structure and chemical species in liquids. The enthalpy of mixing has a minimum value of −120 kJ/mol at 35-40 mol% SiO₂ and is convex upward around 80-90 mol% SiO₂. The entropy of mixing have a maximum value of + 6 J/K-mol at 75 mol% SiO₂, and it decreases with the SiO₂ content to −5 J/K-mol at 40 mol% SiO₂. This decrease in entropy can be accounted for by ideal mixing of Q⁴, Q³, and Q^{0 + 1 + 2} (= Q⁰ + Q¹ + Q²) species in the liquids and is responsible for the negative temperature dependence of the partial molar Gibbs energy of mixing of Na₂O, observed in activity measurements. Comparison of the present results with previous values suggests that a quasi-chemical model and the Adam-Gibbs model overestimate the configurational entropy of mixing of liquids.     

Quantum Brownian motion and the second law of thermodynamics

We consider a single harmonic oscillator coupled to a bath at zero temperature. As is well-known, the oscillator then has a higher average energy than that given by its ground state. Here we show analytically that for a damping model with arbitrarily discrete distribution of bath modes and damping models with continuous distributions of bath modes with cut-off frequencies, this excess energy is less than the work needed to couple the system to the bath, therefore, the quantum second law is not violated. On the other hand, the second law may be violated for bath modes without cut-off frequencies, which are, however, physically unrealistic models. An erratum to this article is available at .     

Gravitational structure formation, the cosmological problem and statistical physics

Models of structure formation in the universe postulate that matter distributions observed today in galaxy catalogs arise, through a complex non-linear dynamics, by gravitational evolution from a very uniform initial state. Dark matter plays the central role of providing the primordial density seeds which will govern the dynamics of structure formation. We critically examine the role of cosmological dark matter by considering three different and related issues: Basic statistical properties of theoretical initial density fields, several elements of the gravitational many-body dynamics and key correlation features of the observed galaxy distributions are discussed, stressing some useful analogies with known systems in modern statistical physics.     

The energetics of metabolism in hydrothermal systems: Calculation of the standard molal thermodynamic properties of magnesium-complexed adenosine nucleotides and NAD and NADP at elevated temperatures and pressures

Calculation of the thermodynamic properties of biomolecules at high temperatures and pressures is fundamental to understanding the energetics of metabolism in hydrothermal systems. Perhaps the most direct interaction between hyperthermophilic microbes and their aquatic and mineralogic habitat involves conversion of environmentally available redox potential into biochemically useful energy. Although chemical thermodynamics can be used to quantify this process, little is known about the thermodynamic properties of the biomolecules involved, especially at high temperatures. However, recent advances in theoretical biogeochemistry make it possible to calculate these properties using the limited experimental data available in the literature, together with group additivity and correlation algorithms, reference model compounds and reactions, and the revised-HKF equations of state. This approach permits calculation of the standard molal thermodynamic properties and equations of state parameters for magnesium-complexed adenosine nucleotides, nicotinamide adenine dinucleotides (NADs), and nicotinamide adenine dinucleotide phosphates (NADPs) as a function of pressure and temperature. The thermodynamic properties and revised-HKF equations of state parameters generated in the present study can be used to carry out comprehensive mass transfer and Gibbs energy calculations to quantify the energetics of microbial energy production in hydrothermal systems.     

Theoretical study of possible products of the combination of H2O and HCN

Twenty-two structures with the empirical formula H₃CNO are presented. These structures are examined since they have the same formula as the H₂O…HCN complex. The H₂O…HCN potential energy surface is of interest to chemists studying the water catalyzed polymerization of HCN. Structures, thermodynamics, and vibrational spectra are examined.     

THE ADSORPTION BEHAVIORS OF 2,6-DICHLOROPHENOL ONTO HYPERCROSSLINKED RESINS

1. INTRODUCTION Chlorophenolic compounds are very toxic, and many are known or suspected human carcinogens. They have been widely used for many industrial purposes. The removals of chlorophenols are of high industrial and environmental interest [1~2]. The adsorption resin is another adsorbent widely employed for isolation and purification of organic substances, treatment of wastewaters, solid phase extraction, and so on. A variety of materials has been developed and tested, such as Amber…     

Effect of Temperature on Thermophysical Properties of Ethanol + Aliphatic Alcohols (C<Subscript>4</Subscript>–C<Subscript>5</Subscript>) Mixtures

Summary. Speeds of sound, densities, and refractive indices of the binary mixtures containing ethanol+(2-methyl-1-propanol, 2-methyl-1-butanol, 1-pentanol, or 3-methyl-1-butanol) were measured at 288.15 ≤ T/K ≤ 323.15 and atmospheric condition in the whole compositional range. The effect of temperature was analyzed by several chemical terms.