Equilibrium, frozen, excess and volumetric properties of dilute solutions

Vapour � liquid equilibrium, thermodynamic and volumetric properties were predicted for three pure hydrofluorocarbons: difluoromethane (R32), pentafluoroethane (R125) and 1,1,1,2 � tetrafluoroethane (R134a) as well as for binary and ternary mixtures of these refrigerants. Three cubic equations of state GEOS3C, SRK (Soave � Redlich � Kwong) and PR (Peng � Robinson) were used. A wide comparison with literature experimental data was made. For the refrigerant mixtures, classical van der Waals mixing rules without interaction parameters were used. The GEOS3C equation, with three parameters estimated by matching several points on the saturation curve (vapor pressure and corresponding liquid volumes), compares favorably to other equations in literature, being simple enough for applications.

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Molecular Transformations in DNA under the Influence of UV-radiation

Current Applied Polymer Science ◽

10.2174/2452271604666200814123505 ◽

2020 ◽

Vol 04 ◽

Author(s):

Vigen G. Barkhudaryan ◽

Gayane V. Ananyan ◽

Nelli H. Karapetyan

Keyword(s):

Uv Radiation ◽

Uv Irradiation ◽

Absorption Spectroscopy ◽

Calf Thymus Dna ◽

Dilute Solutions ◽

Concentrated Solutions ◽

Buffer Solution ◽

Low Concentration ◽

Calf Thymus ◽

Dna Solutions

Background: The processes of destruction and crosslinking of macromolecules occur simultaneously under the influence of ultraviolet (UV) radiation in synthetic polymers, dry DNA and their concentrated solutions. Objective: The effect of UV radiation on calf thymus DNA in dilute solutions subjected to UV- irradiation was studied in this work. Method: The calf thymus DNA was studied in dilute solutions using viscometry, absorption spectroscopy and electrophoresis. Results: It was shown, that at a low concentration of DNA in the buffer solution ([DNA] = 85 μg / ml) under the influence of UV radiation, the processes of destruction of macromolecules and an increase in their flexibility predominate, which is accompanied by a gradual decrease in the viscosity of their solution. In addition, due to the low concentration of the solution, intramolecular crosslinking of macromolecules predominates, which also reduces their size and, consequently, the viscosity of the solution. Conclusion: It was concluded, that in dilute DNA solutions, due to the predominance of the processes of intramolecular crosslinking of macromolecules over intermolecular, only constant processes of decreasing the sizes of DNA macromolecules occur. As a result, its solubility remains virtually unchanged during UV irradiation. The described comments are also excellently confirmed by the results of absorption spectroscopy and electrophoresis

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The non-Newtonian behaviour of dilute solutions of polymers. II. The non-Newtonian viscosity of polystyrene solutions in relation to the thermodynamic quality of the solvent

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19682130 ◽

1968 ◽

Vol 33 (7) ◽

pp. 2130-2141 ◽

Cited By ~ 2

Author(s):

O. Quadrat ◽

M. Bohdanecký

Keyword(s):

Dilute Solutions ◽

Newtonian Viscosity ◽

Thermodynamic Quality

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