The dependence of the polarographic diffusion current on the viscosity in concentrated solutions of saccharose

1947 ◽  
Vol 12 ◽  
pp. 429-435 ◽  
Author(s):  
I. Vavruch
2020 ◽  
Vol 04 ◽  
Author(s):  
Vigen G. Barkhudaryan ◽  
Gayane V. Ananyan ◽  
Nelli H. Karapetyan

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


1984 ◽  
Vol 49 (5) ◽  
pp. 1109-1115
Author(s):  
Jindřich Novák ◽  
Zdeněk Kodejš ◽  
Ivo Sláma

The density, viscosity, and electrical conductivity of highly concentrated solutions of ammonium nitrate in dimethyl sulphoxide have been determined over the temperature range 10-60 °C and the concentration range 7-50 mol% of the salt. The variations in the quantities as a function of temperature and concentration have been correlated by empirical equations. A comparison is made between the transport properties for the present system, aqueous solutions of ammonium nitrate, and calcium nitrate solutions in dimethyl sulphoxide.


1985 ◽  
Vol 50 (12) ◽  
pp. 2697-2714
Author(s):  
Arnošt Kimla ◽  
Jiří Míčka

The formulation and solution of a boundary value problem is presented, describing the influence of the free convective diffusion on the forced one to a sphere for a wide range of Rayleigh, Ra, and Peclet, Pe, numbers. It is assumed that both the free and forced convection are oriented in the same sense. Numerical results obtained by the method of finite differences were approximated by an empirical formula based on an analytically derived asymptotic expansion for Pe → ∞. The concentration gradient at the surface and the total diffusion current calculated from the empirical formula agree with those obtained from the numerical solution within the limits of the estimated errors.


2004 ◽  
Vol 69 (2) ◽  
pp. 419-425 ◽  
Author(s):  
Katarína Gmucová ◽  
Jozef Orlický ◽  
Juraj Pavlásek

The redox reaction of the neurotransmitter dopamine at the carbon fibre microelectrode was studied by several electrochemical methods. It was found that under conditions usual in a living body, the diffusion current fullfils, within experimental errors, the behavior theoretically predicted by the Cottrell equation. Nevertheless, attention should be paid to the fact that unsupported or weakly supported conditions give rise to a non-Cottrell response of diffusion current. Moreover, similar changes were observed if the dopamine concentration was either lower such as several units of μmol l-1, or about 100 μmol l-1 or higher. The non-Cottrell behavior of diffusion current involves the nonlinearity of the dopamine calibration curve obtained by pulse techniques. The present work is aimed at pointing out that such behavior of the measured data could lead to misinterpretation of the obtained dopamine concentration. Similar features could be also achieved for the other catecholamines.


2009 ◽  
Vol 152 (1-2) ◽  
pp. 48-88 ◽  
Author(s):  
Martin Z. Bazant ◽  
Mustafa Sabri Kilic ◽  
Brian D. Storey ◽  
Armand Ajdari

RSC Advances ◽  
2021 ◽  
Vol 11 (18) ◽  
pp. 10929-10934
Author(s):  
Chuangui Cao ◽  
Zhihui Zhao ◽  
Yong Qi ◽  
Hui Peng ◽  
Kuanjun Fang ◽  
...  

The solvent, DEA, reduces the dye aggregation that may be caused by the weak hydrogen bonding and relatively smaller steric hindrance effect.


2021 ◽  
Vol 176 ◽  
pp. 107949
Author(s):  
G. Ghibaudo ◽  
M. Aouad ◽  
M. Casse ◽  
T. Poiroux ◽  
C. Theodorou

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