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Physico-chemical properties of Chitosan films

100%

Balau L., Lisa G., Popa M., Tura V., Melnig V.

Open Chemistry

2004

vol. 2

issue 4

638-647

Chitosan films obtained by dry phase inversion were prepared from an aqueous solution of chitosan in acetic acid. The films, of thickness less than 20 μm, were transparent, very flexible and had smooth surfaces. Increasing the film thickness induced an increase of the internal tensions and the consequent formation of a rough surface. Structural investigations by X-ray diffraction and Fourier transform IR analysis, showed that the chitosan films, as prepared, are amorphous. Further annealing to evaporate acetic acid and water traces, changed the amorphous phase into a more ordered phase, characterized by diffraction peaks at 2θ values of 9, 17, 20 and 23 degrees. Thermal investigations by TG, DTG, and DTA revealed that the decomposition of the chitosan films as prepared proceeds in two stages, starting from 180°C and 540°C.

Interaction of fibrinogen with nanosilica

84%

Rugal A., Gun’ko V., Barvinchenko V., Turov V., Semeshkina T., Zarko V.

Open Chemistry

2007

vol. 5

issue 1

32-54

Interaction of human plasma fibrinogen (HPF) with fumed nanosilica A-300 in a phosphate buffer solution (PBS) was studied using 1H NMR spectroscopy with layer-by-layer freezing-out of bulk and interfacial water in the temperature range of 210–273 K, TSDC (90 T FTIR, and UV spectroscopy methods. An increase in concentration of HPF in the PBS leads to a decrease in amounts of structured water (frozen at T FTIR and UV spectra show that the HPF adsorption on silica leads to structural changes of the protein molecules. These changes and formation of hybrid HPF/A-300 aggregates can increase the rate of clotting that is of importance on nanosilica application as a component of tourniquet preparations. [...]

Behaviour of pure water and water mixture with benzene or chloroform adsorbed onto ordered mesoporous silicas

67%

Gun’ko V., Turov V., Turov A., Zarko V., Gerda V., Yanishpolskii V., Berezovska I., Tertykh V.

Open Chemistry

2007

vol. 5

issue 2

420-454

Structural characteristics of synthesized ordered mesoporous silicas MCM-41, MCM-48 and SBA-15 were studied using XRD, nitrogen adsorption and FTIR methods. Pure water and mixtures with water/benzene and water/chloroform-d adsorbed onto silicas were studied by 1H NMR spectroscopy with layer-by-layer freezing-out of bulk and interfacial liquids. Concentrated aqueous suspensions of MCM-48 and SBA-15 were studied by thermally stimulated depolarization current (TSDC) method. Benzene and chloroform-d can displace a portion of water to broad pores from the pore walls and from narrower pores, especially in the case of a large excess of an organic solvent. This process is accompanied by diminution of both interaction energy of water with an adsorbent surface and freezing temperature depression of adsorbed water. The effect of nonpolar benzene on pore water is much stronger than that of weakly polar chloroform-d. Modifications of the Gibbs-Thomson relation to describe the freezing point depression of mixtures of immiscible liquids confined in pores allow us to determine distribution functions of sizes of structures with unfrozen pore water and benzene. [...]

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3 Open Chemistry

2 2007

1 2004

2 Gun’ko V.

2 Turov V.

2 Zarko V.

1 Balau L.

1 Barvinchenko V.

1 Berezovska I.

1 Gerda V.

1 Lisa G.

1 Melnig V.

1 Popa M.

1 Rugal A.

1 Semeshkina T.

1 Tertykh V.

1 Tura V.

1 Turov A.

1 Yanishpolskii V.

Search results

Physico-chemical properties of Chitosan films

Interaction of fibrinogen with nanosilica

Behaviour of pure water and water mixture with benzene or chloroform adsorbed onto ordered mesoporous silicas