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Vapor pressure (P) data of pure substances in gas/solid-liquid equilibrium is important for scientific research and practical applications. Due to the large temperature range going from melting point to critical point, it is an impossible task to determine the P of a pure substance at each temperature point. Up to now, there is no general equation that can accurately describe the relation between temperature (T) and P for all pure substances. Utilizing Boltzmann distribution, we presented a general expression, ln P = a + bT + cln(T) + d(1/T), for the P of pure substances, that is, the P-T dependence is nearly exponential over the entire range of liquid and solid existence. Furthermore, on the base of above equation, we established a corrected general equation to express the liquid vapor pressure within temperature in going from melting point to critical point.lnP=a+bT+cTT/Tb+d(ln(T))+f(ln(T))T/Tb+g(1/T)The results show that the corrected equation has the advantages of universality, simplicity, and high calculation accuracy for the vapor pressure involving liquid simple substances, liquid inorganic and liquid organic compounds.

For Descartes, our minds are not natural causes because they are not themselves objects; rather, they are the activities that identify objects. In short, they are our challenges to the natural order of things, both in how we adapt to novel situations (as exhibited in what has been called the "rational action test") and in how we respond in unexpected yet appropriate ways to linguistic cues (in the "language test"). Because these tests reveal ways in which our minds (as "pure," creative, willful, and immortal substances) introduce novelty into nature, we are not determined (as animals are) by other objects. That is, our rational or linguistic activities are challenges to the order of nature precisely because they are not part of, but rather constitute, nature. Accordingly, "real" (creative) speech is logically prior to finite differentiations and is not limited by laws of nature that constrain animal behavior. [ABSTRACT FROM AUTHOR]

Ultra-low-radioactivity titanium alloys are promising materials for the manufacture of low-background detectors which are being developed for experiments in astroparticle physics and neutrino astrophysics. Structural titanium is manufactured on an industrial scale from titanium sponge. The ultra-low-background titanium sponge can be produced on an industrial scale with a contamination level of less than 1 mBq/kg of uranium and thorium isotopes. The pathways of contaminants during the industrial production of structural titanium were analyzed. The measurements were carried out using two methods: inductively coupled plasma mass spectroscopy (ICP-MS) and gamma spectroscopy using high-purity germanium detectors (HPGes). It was shown that the level of contamination with radioactive impurities does not increase during the remelting of titanium sponge and mechanical processing. We examined titanium alloy samples obtained at different stages of titanium production, namely an electrode compaction, a vacuum arc remelting with a consumable electrode, and a cold rolling of titanium sheets. We found out that all doped samples that were studied would be a source of uranium and thorium contamination in the final titanium alloys. It has been established that the only product allowed obtaining ultra-low-background titanium was the commercial VT1-00 alloy, which is manufactured without master alloys addition. The master alloys in the titanium production process were found cause U/Th contamination. [ABSTRACT FROM AUTHOR]

The theory of differential equations is a powerful tool necessary for constructing mathematical models of various applied problems and their solution. The study and analysis of the general differential relations between the derivatives of the thermodynamic functions of substances is a new direction in the theory of their thermodynamic properties. This research is the development of thermodynamics associated with the establishment and use of differential equations. This paper presents two new thermodynamic relationships between thermal variables pressure, absolute temperature, and specific volume. They relate first-order partial derivatives with unmixed second-order derivatives for these variables. Revealing new general relations of thermodynamics made it possible to formulate and solve a number of problems, among which we can note: creation of algorithms for calculating second-order mixed derivatives for a given thermal equation of state; analysis of the features of the second mixed derivatives at the critical point of pure substance; investigations of the general thermodynamic equations with entropy. The procedure for establishing new equations is based on the use of a rigorous mathematical apparatus and Maxwell's differential equations. Therefore, they are of a general nature, that is, they are valid for any pure substance or any mixture of fixed composition. They are also applicable to any model of the equation of state of these substances. With a formal approach to the concept of the term "equation of state", the new relations themselves can be considered as the equation of state of substance. The obtained new relations can be used to develop the theory of the thermodynamic properties of substances. In particular, in this work it is shown that the ratios of two partial derivatives of pressure over the volume, which are zero critical conditions, have no singularities at the critical point itself

This article is a broad personal reflection about the language of chemistry, deriving from decades of experience in both research and teaching. The three levels of thought as represented by the Johnstone triangle, a critical attitude towards systematic nomenclature, the concept of pure substance, and the central significance of structural formulas as the most prominent form of representation in chemistry, are the main topics discussed. The chemical transliteration of the Platonic solids is presented as a mean of expression unique to chemistry.

The theory of differential equations is a powerful tool necessary for constructing mathematical models of various applied problems and their solution. The study and analysis of the general differential relations between the derivatives of the thermodynamic functions of substances is a new direction in the theory of their thermodynamic properties. This research is the development of thermodynamics associated with the establishment and use of differential equations. This paper presents two new thermodynamic relationships between thermal variables pressure, absolute temperature, and specific volume. They relate firstorder partial derivatives with unmixed second-order derivatives for these variables. Revealing new general relations of thermodynamics made it possible to formulate and solve a number of problems, among which we can note: creation of algorithms for calculating second-order mixed derivatives for a given thermal equation of state; analysis of the features of the second mixed derivatives at the critical point of pure substance; investigations of the general thermodynamic equations with entropy. The procedure for establishing new equations is based on the use of a rigorous mathematical apparatus and Maxwell's differential equations. Therefore, they are of a general nature, that is, they are valid for any pure substance or any mixture of fixed composition. They are also applicable to any model of the equation of state of these substances. With a formal approach to the concept of the term "equation of state", the new relations themselves can be considered as the equation of state of substance. The obtained new relations can be used to develop the theory of the thermodynamic properties of substances. In particular, in this work it is shown that the ratios of two partial derivatives of pressure over the volume, which are zero critical conditions, have no singularities at the critical point itself. [ABSTRACT FROM AUTHOR]

Special techniques for deep purification of ZnO and WO3 have been developed in this work. A ZnWO4 single crystal has been grown by the Czochralski method using purified ZnO and WO3 chemicals, along with the ZnWO4 crystal-etalon, which has been grown at the same conditions using commercially available 5N ZnO and WO3 chemicals. The actual accidental impurities compositions of both the initial chemicals and the grown crystals have been measured by inductively coupled plasma mass-spectrometry. A complex of comparative spectroscopic studies of the crystals has been performed, including optical absorption spectra, photo-, X-ray-, and cathodoluminescence spectra and decay kinetics, as well as the photoluminescence excitation spectra. The revealed differences in the measured properties of the crystals have been analyzed in terms of influence of the accidental impurities on these properties. [ABSTRACT FROM AUTHOR]

The Joule-Thomson effect is widely used in the design of refrigeration and cryogenic installations. Interest in it does not weaken, despite the one and a half month period from the day of its opening. This is explained by the fact that the so-called inversion curve of the throttle effect in thermodynamics is ideal. This circumstance contributes to a deeper study of the inversion curve when developing the equations of state of real gases. It should also be taken into account that there are no studies on the peculiarities of the inversion curve as a mathematical object. For example, no publications were found that studied derivatives on this curve. The purpose of the work is to establish the values and carry out an analysis of the features of a number of first and second derivatives of thermodynamic functions on the Joule-Thomson line. Two approaches are used: in the first one, an analytical description of inversion curves in π,φ- and π,τ-coordinates is used, in the second one, modern means of symbolic calculations are used. Analytical dependences were obtained for the parameters of the Joule-Thomson curve when using the given van der Waals equation of state in a dimensionless form. This choice is due to the fact that, firstly, the equation does not depend on the type of pure substance; secondly, for this equation, as further studies show, all solutions can be obtained analytically thanks to the modern capabilities of computing technology. In addition, no results of symbolic calculations for the inversion curve based on the van der Waals equation of state were found in the literature. Graphical dependences for first- and second-order derivatives on the inversion curve are given and analyzed. It was concluded that the studied derivatives are monotonic functions of the given temperature. It was established that these derivatives can have extremum points and infinite values only at the upper inversion temperature. The use of general thermodynamic relations to determine the mixed derivative of the second order on the inversion curve is presented. [ABSTRACT FROM AUTHOR]

Ultra-low-radioactive titanium is the main perspective material for cryostat fabrication in dark matter search experiments. The pathways of the uranium and thorium contamination of Ti sponges produced by the Kroll process were analyzed. The general role of Mg in Ti sponge contamination by U and Th was established. It was found that when transformed to MgCl2 in the Kroll process, Mg was purified from U and Th, and further MgCl2 reduction and sublimation makes it possible to produce low-radioactive Ti sponges. [ABSTRACT FROM AUTHOR]

The present study aimed to develop, introduce, and conduct an activity for the integration of augmented reality to the jigsaw IV technique in a planned and systematic manner. The activity developed for secondary school students is related to the "Pure Substances" subject which it is included in the "Particulate structure of matter" topic. The activity was arranged as; an attractive introduction, expert group studies, home team studies and assessment stages. Whereas augmented reality was used during the "home team study" stage for the jigsaw IV technique. Students are given the opportunity to examine a lot of resources during the "expert group study" and "home team study" stages to encourage them to be educated as science literate individuals. Whereas the students are subject to individual examinations during the assessment stage. This activity is an example for increasing the usage area of augmented reality in the education environment. Moreover, it is also considered that the activity will provide benefits in ensuring meaningful learning by embodying abstract concepts and helping students in improving 21st-century skills (e.g., cooperative study skills, learning to learn, communication, entrepreneurship, adaptation, leadership, social skills, and responsibility, etc.). [ABSTRACT FROM AUTHOR]

This article is a broad personal reflection about the language of chemistry, deriving from decades of experience in both research and teaching. The three levels of thought as represented by the Johnstone triangle, a critical attitude towards systematic nomenclature, the concept of pure substance, and the central significance of structural formulas as the most prominent form of representation in chemistry, are the main topics discussed. The chemical transliteration of the Platonic solids is presented as a mean of expression unique to chemistry., (Copyright 2023 Antonio Togni. License: This work is licensed under a Creative Commons Attribution 4.0 International License.)

Abstract: An equation of state to describe the complete phase diagram of a pure substance is developed. The equation of state is constructed by using a generic cubic equation plus the term . This term (where f >0 and e are adjustable parameters) is the attractive contribution of the solid phase. It has a volume short-range contribution, and extends the traditional use of a cubic equation, incorporating the thermodynamics description of the solid phase, which allows to represent the experimental triple point, the solid–liquid, and the solid–vapor phase transitions, together with the traditional description of the liquid–vapor transition. For the solid–liquid phase coexistence at any temperature, molar volume predictions of the solid phase define a curve which never connects to its corresponding liquid phase curve. This feature is in agreement with experimental evidences that seem to not accept the existence of a solid–liquid critical point. Finally, calculations for the complete phase diagram for carbon dioxide and argon were carried out in order to show the capabilities and features of the equation of state, and these results were also compared with other predictions from the literature. [Copyright &y& Elsevier]

Abstract: Thermal energy storage is now a key parameter to overcome the delay between energy supply and demand in many applications. To address this issue, the use of phase change materials (PCM) tends to be more and more common. Given the attempted objectives of such applications, performances of the PCM are a cornerstone of the whole system. Therefore, a correct determination of their intrinsic properties is crucial. To perform this step, one may use a calorimetry experiment. Unfortunately, the interpretation of the thermogram is not straightforward and consequently, when not feasible at all, estimations may be wrong. As an example, pure substance as sometimes said to melt at a non-uniform temperature (their enthalpy being smeared over several degrees), and binary solutions are associated with liquidus temperature and latent heat that do not match the correct form of their enthalpy. The present work proposes a new method to avoid such issues. To summarize the novelty of our approach, the main idea is to use an inverse method to identify the thermodynamical parameters of the sample through a matching step between the experimental curves and theoretical ones. It means that contrary to many others methods, we do not directly extrapolate the thermodynamical properties (e.g. the enthalpy) from the thermogram. Instead, we suppose an a priori formulation of the enthalpy, based on thermodynamical principles. Thus the thermodynamical parameters are inputs of which only values are computed from the experiments. Capabilities of the method are shown on pure substances and binary solutions examples. [Copyright &y& Elsevier]

The finiteness and positive value of the slope of the saturation curve at the critical point according to its location in the region of a thermodynamic surface restricted by the curves of inversion and saturation are substantiated. It is shown that any two derivatives of the first order formed with respect to volume, internal energy, entropy, enthalpy, and the Helmholtz energy, one of which is taken at a fixed value of pressure and the other at a fixed value of temperature, are equal in the critical state. New sets of the critical conditions for a pure substance are obtained. [ABSTRACT FROM AUTHOR]

The aim of the present analysis was to study the influence of the sample concentration on the measured antioxidant capacity, since such investigations are scarce but necessary to ensure the reproducibility of the results. Pure substances (ascorbic acid, gallic acid, Trolox®, uric acid) and food extracts (strawberry nectar, tomato extract, white tea) were analysed using seven common antioxidant capacity assays (three versions of Trolox equivalent antioxidant capacity, TEAC; ferric reducing antioxidant power, FRAP; photochemiluminescence, PCL; oxygen radical absorbance capacity, ORAC and total phenolics assay). For all applied pure substances and in most of the assays effects of the sample concentration on the measured antioxidant capacity were observed. Since it remains speculative how sample concentration does affect the measured antioxidant capacity exactly, it is strongly recommended to use at least three sample concentrations for analysis to detect and to discuss concentration-dependent effects. [ABSTRACT FROM AUTHOR]

Abstract: An equation of state (EOS) for square-well chain molecules with variable range developed on the basis of statistical mechanics for chemical association in our previous work is employed for the calculations of pVT properties and vapor–liquid equilibria (VLE) of pure non-associating fluids. The molecular parameters for 73 normal substances and 46 polymers are obtained from saturated vapor pressure and liquid molar volume data for normal fluids or pVT data for polymers. Linear relations are found for the molecular parameters of normal fluids with their molecular weight of homologous compounds. This indicates that the model parameters of homologous series, subsequently pVT and VLE, can be predicted when experimental data are not available. The predicted saturated vapor pressures and/or liquid volumes are satisfactory through the generalized model parameters. The calculated VLE and pVT for normal fluids and polymers by this EOS are compared with those from other engineering models, respectively. [Copyright &y& Elsevier]

A simple method of synthesis of high pure tris(8-hydroxyquinoline)aluminum (Alq3) from commercial available 5N Al2O3 and 8-hydroxyquinolinol has been developed. One-step exchange chemical reaction has been conducted under controlled 8-hydrixyquinoline vapor at a temperature of 190–240 °C with water removal by phosphorus anhydride. According to analysis of inductively coupled plasma mass-spectrometry, the chemical purity of synthesized Alq3 was 99.998 wt%. Photoluminescence of the synthesized Alq3 has been measured and slightly differed from those of Alq3 obtained by traditional organic synthesis. [ABSTRACT FROM AUTHOR]