Heats of vaporization of nonelectrolytes

1979 ◽  
Vol 44 (2) ◽  
pp. 307-312
Author(s):  
Petr Kyselka ◽  
Jiří Rameš ◽  
Karel Procházka
Keyword(s):  
Experimental Data ◽  
Chemical Properties ◽  
Approximate Expression ◽  
Maximum Deviation ◽  
First Order ◽  
Critical Data ◽  
Physico Chemical ◽  
Theory Of Liquids ◽  
Nonpolar Liquids ◽  
Experimental Values

The first-order perturbation theory of liquids was used for developing an approximate expression suitable for a rapid calculation of the heat of vaporization of nonpolar liquids formed by approximately spherical molecules. The calculation uses only available physico-chemical properties of substances, namely the critical data. The results are tested by a comparison with existing experimental data on a series of nonpolar substances. The agreement between calculated values and experimental data is relatively good. The maximum deviation between theoretical and experimental values does not exceed ±10%.

scholarly journals Physico-chemical Properties of Solutions of Lithium Bis(fluorosulfonyl)imide (LiFSI) in Dimethyl Carbonate, Ethylene Carbonate, and Propylene Carbonate

2021 ◽  
Author(s):  
Johannes Neuhaus ◽  
Erik von Harbou ◽  
Hans Hasse
Keyword(s):  
Experimental Data ◽  
Electrical Conductivity ◽  
Propylene Carbonate ◽  
Dimethyl Carbonate ◽  
Ethylene Carbonate ◽  
Chemical Properties ◽  
Lithium Ion ◽  
Solvent System ◽  
Empirical Correlations ◽  
Physico Chemical

Battery performance strongly depends on the choice of the electrolyte-solvent system. Lithium bis(fluorosulfonyl)imide (LiFSI) is a highly interesting novel electrolyte. Information on physico-chemical properties of solutions of LiFSI, however, is scarce. Therefore, the density, shear viscosity, and electrical conductivity of solutions of LiFSI in three pure solvents that are interesting for battery applications: dimethyl carbonate (DMC), ethylene carbonate (EC), and propylene carbonate (PC), were studied experimentally at temperatures between 273 K and 333 K at 1 bar and concentrations of LiFSI up to 0.45 mol mol−1 in the present work. Empirical correlations of the experimental data are provided. The comparison of the data of this work with the corresponding LiPF6 data underpins the attractiveness of LiFSI as an electrolyte in lithium ion batteries.

Physico-chemical properties of the ternary system urea-ammonium nitrate-water. Surface tension

1985 ◽  
Vol 50 (8) ◽  
pp. 1629-1635 ◽  
Author(s):  
Marie Šišková ◽  
Jiřina Hejtmánková ◽  
Lidmila Bartovská
Keyword(s):  
Surface Tension ◽  
Ternary System ◽  
Ammonium Nitrate ◽  
Binary Systems ◽  
Chemical Properties ◽  
Ternary Systems ◽  
Surface Tensions ◽  
Physico Chemical ◽  
Urea Ammonium Nitrate ◽  
Experimental Values

Surface tension of two binary systems ammonium nitrate-water and urea-water and of the ternary system ammonium nitrate-urea-water was measured as a function of concentration at 20 and 40 °C. The experimental values were compared with those calculated from the relations which were proposed for calculating surface tensions of ternary systems from measured surface tensions of both binary systems.

Two Dimensional Graphite Films on Metals and Their Intercalation

1997 ◽  
Vol 11 (16) ◽  
pp. 1865-1911 ◽  
Author(s):  
N. R. Gall ◽  
E. V. Rut'kov ◽  
A. Ya. Tontegode
Keyword(s):  
Experimental Data ◽  
Chemical Properties ◽  
Metal Substrate ◽  
Two Dimensional ◽  
Graphite Layer ◽  
High Adsorption ◽  
Real Nature ◽  
Physico Chemical ◽  
Active Metal ◽  
Graphite Film

Two-dimensional graphite films (2DGF) on solids are wonderful objects, real nature-made two-dimensional crystals. Formation on active metal surface of a 2DGF with extremely high adsorption, chemical and catalytic passivity leads to a number of staggering effects. The review is devoted to 2DGF on metals and their nature, structure, modes of formation and physico chemical properties. A nature of absorption bond between 2DGF and metal substrate is discussed in details. A special attention is paid to intercalation of 2DGF — a process when foreign atoms and even molecules (fullerenes C 60 molecules) spontaneously penetrate between graphite film and metal substrate. Modes of intercalation are discussed and a mechanism of it, based on thermal movements of carbon atoms of a graphite layer, proposed earlier, is used for explanation of experimental data. A new, practically important effect-superefficient diffusion of alkaline atoms into transition metal bulk, covered by 2DGF, is reported.

Electrical Resistivity of Noble Metals

1973 ◽  
Vol 51 (21) ◽  
pp. 2225-2232 ◽  
Author(s):  
Satya Pal
Keyword(s):  
Experimental Data ◽  
Electrical Resistivity ◽  
Noble Metals ◽  
Secular Equation ◽  
Transport Coefficients ◽  
Boltzmann Transport ◽  
Dynamical Models ◽  
First Order ◽  
Experimental Values ◽  
Theoretical Results

The temperature variation of the electrical resistivity of copper, silver, and gold has been studied within the free electron approximation on the basis of the lattice dynamical models of Chéveau, and Bhatia and Horton. The first-order variational solution of the Boltzmann transport equation as developed by Ziman has been incorporated in the study for the calculation of the transport coefficients of noble metals. The force constants appearing in the secular equation for the lattice vibrations have been estimated with the help of the experimental values of the elastic constants of the noble metals. The phonon spectrum has been calculated by the modified Houston spherical six-term procedure as elaborated by Betts et al. The Normal and the Umklapp contributions to the electrical resistivity have been considered separately in the present study. A comparison of the theoretical results with the experimental data shows that the calculations are able to explain satisfactorily the temperature dependence of the electrical resistivity of the noble metals. However, as compared to the Bhatia–Horton model, the theoretical resistivity values of the noble metals as furnished by the Chéveau model give a better overall fit with the experimental data.

scholarly journals A Theoretical Investigation of the Structural, Spectroscopic and Optical Properties of Adenine

2016 ◽  
Vol 64 (1) ◽  
pp. 77-81 ◽  
Author(s):  
M Alauddin ◽  
MM Islam ◽  
MK Hasan ◽  
T Bredow ◽  
MA Aziz
Keyword(s):  
Experimental Data ◽  
Optical Properties ◽  
Chemical Shift ◽  
Density Functional ◽  
Hybrid Approach ◽  
Maximum Deviation ◽  
Spectra Analysis ◽  
Td Dft ◽  
Stretching Vibration ◽  
Experimental Values

The structural, spectroscopic (IR, NMR and UVis) UV-Vis) and optical properties of adenine (6-aminopurine, C5H5N5) are investigated theoretically using HF/DFT hybrid approach B3LYP. The calculated results are compared with available experimental data. The optimized bond distances and bond angles are converged within ±0.01 Å and ±0.8° with respect to the experimental values. The investigation of1H NMR chemical shift spectra of the aromatic C-H protons shows that the maximum deviation of the calculated chemical shift is ~ 0.53 ppm compared to the experimental data. The calculated vibrational spectra analysis shows four distinct IR active mode of vibrations which are assigned as scissoring vibration of –NH2, symmetric stretching vibration of, –NH2, free –NH vibration and anti-symmetric stretching vibration of–NH2, respectively The electronic and optical properties are calculated by Time Dependent Density Functional Theory (TD-DFT) approach. A reasonable agreement is obtained for the calculated optical absorption energy with the experimental value. Dhaka Univ. J. Sci. 64(1): 77-81, 2016 (January)

Release characteristics of an essential oil component encapsulated with cyclodextrin shell matrices

2020 ◽  
Vol 17 ◽  
Author(s):  
Zhe Li ◽  
Wangwen Wen ◽  
Xulong Chen ◽  
Lin Zhu ◽  
Genjinsheng Cheng ◽  
...  
Keyword(s):  
Particle Size ◽  
Essential Oils ◽  
Molecular Modelling ◽  
Chemical Properties ◽  
Order Kinetic ◽  
First Order ◽  
Binding Behavior ◽  
Physico Chemical ◽  
Ft Ir ◽  
The Stability

Background: Essential oils are poor aqueous solubility and high volatility compounds. The encapsulation of essential oils with cyclodextrins (CDs) can protect them from the adverse environmental conditions and improve their stability. Therefore, increasing the functional capabilities of essential oils when they were used as additives in pharmaceutical and food systems. Additionally, the release of active compounds is an important issue. However, there were few studies about the effect of different CDs on the release of drugs after encapsulation. Therefore, the information on the study of release models is considerably limited. Objective: This study aimed to (i) characterize the physico-chemical properties and release behavior of myrcene encapsulated in the four different shell matrices of α-CD, β-CD, γ-CD and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), which were selected from the perspective of stability, and (ii) determine the release mechanism of myrcene in inclusion complexes (ICs). Methods: ICs of myrcene and four CDs were prepared by freeze-drying. The physico-chemical properties of ICs were fully characterized by laser diffraction particle size analyzer, scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FT-IR) and differential scanning calorimeter (DSC). The release behaviors of ICs at 50, 60, 70 and 80 °C were determined and described by zero-order or first-order kinetics with the Henderson-Pabis, Peppas, Avrami and Page mathematical models. Moreover, the possible binding modes of ICs were identified with molecular modelling technique. Results: Firstly, the structure of particle size distribution (PSD), FT-IR, DSC and SEM showed that (i) CDs could effectively encapsulate the myrcene molecules, and (ii) the release kinetics were well simulated by Avrami and Page models. Secondly, the release rates of the ICs experienced unsteady state in the early stage, and gradually became almost constants period after 20 hours. Except that the release of myrcene in γ-CD/myrcene belonged to the first-order kinetic, the release models of the remaining three ICs belonged to diffusion mode. Thirdly, the calculated binding energies of the optimized structures for α-CD/myrcene, β-CD/myrcene, γ-CD/myrcene, and HP-β-CD/myrcene ICs were −4.28, −3.82, −4.04, and −3.72 kcal/mol, respectively. Finally, the encapsulation of myrcene with α-CD and β-CD was preferable according to the stability and release characteristics. Conclusion: The encapsulation of myrcene was profoundly affected by the type of CDs, and the stability could be improved by complexation with suitable CDs. The binding behavior between guest and CD molecules, and the release profile of the guest molecules could be effectively explained by the kinetics parameters and molecular modelling. This study can provide an effective basis and guide for screening suitable shell matrices.

The effects of lipophilicity on the inhibition of denaturation of serum albumin and on the activation of fibrinolysis observed with a series of benzyloxyarylaliphatic acids

1983 ◽  
Vol 48 (4) ◽  
pp. 1077-1088 ◽  
Author(s):  
Miroslav Kuchař ◽  
Václav Rejholec ◽  
Zdeněk Roubal ◽  
Oluše Matoušová
Keyword(s):  
Experimental Data ◽  
Regression Analysis ◽  
Serum Albumin ◽  
Biological System ◽  
Antiinflammatory Activity ◽  
Chemical Parameters ◽  
Membrane Stabilization ◽  
Physico Chemical ◽  
Experimental Values

Activation of fibrinolysis and inhibition of denaturation of serum albumin by a series of substituted benzyloxyarylaliphatic acids have been measured and analyzed in relation to the physico-chemical parameters of these acids. The lipophilicity of the benzyloxy derivatives was characterized both by the tabulated parameters π and by experimental data obtained by TLC. Regression analysis has revealed that the derivatives manifest higher lipophilicities in both the activation of fibrinolysis and the inhibition of denaturation, and that these lipophilicities are better described by the tabulated data than by experimental values. Taking into account the earlier results of regression analysis of erythrocyte membrane stabilization and antiinflammatory activity it can be judged that the role of lipophilicities of these substances is influenced by the nature of their interaction with the biological system.

Physico-chemical properties of the ternary system urea-ammonium nitrate-water. Density

1983 ◽  
Vol 48 (4) ◽  
pp. 1097-1103
Author(s):  
Ludmila Bartovská ◽  
Jiřina Hejtmánková ◽  
Marie Šišková ◽  
Lubomír Jäger
Keyword(s):  
Experimental Data ◽  
Ternary System ◽  
Ammonium Nitrate ◽  
Binary Systems ◽  
Chemical Properties ◽  
Water Density ◽  
Physico Chemical ◽  
Temperature Dependences ◽  
Urea Ammonium Nitrate

Density of the ternary system urea-ammonium nitrate-water was measured in the range of overall concentrations 0-75 mass % at temperatures of 0, 20, 30 and 40 °C. The experimental data are compared with the values calculated from the relation obtained by combining the temperature dependences of densities of the binary systems urea-water and ammonium nitrate-water.

Modeling of the Soybean Grains Hydration by a Distributed Parameters Approach

2009 ◽  
Vol 5 (3) ◽  
Author(s):  
Mônica Ronobo Coutinho ◽  
Edilson Sadayuki Omoto ◽  
Wagner André dos Santos Conceição ◽  
Cid Marcos Gonçalves Andrade ◽  
Luiz Mario de Matos Jorge
Keyword(s):  
Differential Equation ◽  
Experimental Data ◽  
Mathematical Model ◽  
Partial Differential Equation ◽  
Moisture Content ◽  
Maximum Deviation ◽  
Experimental Conditions ◽  
First Order ◽  
Distributed Parameters ◽  
Content Variation

A mathematical model with distributed parameters was proposed to describe the absorption of water by soybeans, in order to evaluate the moisture content variation with time inside the grains. This model was represented by a partial differential equation (second order relative to position and first order relative to time), whose parameters were numerically adjusted using a minimum squares method. For this purpose, available MATLAB® routines were used, together with experimental data obtained from hydration tests where soybeans were immersed in liquid water at temperatures of 10, 20, 30, 42 and 49°C. According to the results, the model was able to represent the main characteristics of the hydration process, with a maximum deviation of 10% in the whole set of experimental conditions.

Decoration of specific sites on freeze-fractured membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 140-141
Author(s):  
H. Gross ◽  
H. Moor
Keyword(s):  
Pure Water ◽  
Freeze Fracture ◽  
Chemical Properties ◽  
Surface Forces ◽  
Sulfate Pentahydrate ◽  
Copper Sulfate Pentahydrate ◽  
Physico Chemical ◽  
Water Of Hydration ◽  
Small Container ◽  
Binding Forces

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.

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