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1.
Structural characterisation of such bio-objects as fibrinogen solution, yeast cells, wheat seeds and bone tissues has been done using two versions of cryoporometry based on the integral Gibbs-Thomson (IGT) equation for freezing point depression of pore liquids and the measurements by 1H NMR spectroscopy (180-200 < T < 273 K) and the thermally stimulated depolarisation current (TSDC) method (90 < T < 273 K) of structured water. The IGT equation was solved using a self-consisting regularization procedure including the maximum entropy principle applied to the distribution function of pore size (PSD). Both methods give clear pictures of changes in the structural characteristics caused, e.g., by hydration and swelling of wheat seeds and yeast cells, coagulation and interaction of fibrinogen with solid nanoparticles in the aqueous media, and the human bone tissue disease. 相似文献
2.
Gun'ko VM Mikhailova IV Zarko VI Gerashchenko II Guzenko NV Janusz W Leboda R Chibowski S 《Journal of colloid and interface science》2003,260(1):56-69
The interaction of fumed silica A-300 (S(BET) = 297 m2 g(-1)) with bovine serum albumin (prepared by different methods), ovalbumin, human hemoglobin, and gelatin as a function of pH, salinity, and concentrations of components in aqueous medium was studied by adsorption and photon correlation spectroscopy (PCS) methods. Comparison of equilibrium (incubation time t(i) approximately 1 h) adsorption of proteins on A-300, minute (t(i) approximately 1 min) flocculation rate, and the particle size distributions measured by the PCS method shows different rearrangement of particle swarms depending on pH, salinity, and concentration of proteins, especially at pH close to IEP of silica or proteins. The electrokinetic mobility of protein/silica swarms is greater than that of individual components at pH far from the IEP of proteins. Changes in the Gibbs free energy (DeltaG) on protein adsorption depend on pH (-DeltaG is minimal at pH 2, close to the IEP of silica, and maximal at pH between the IEP of protein and silica), concentration (-DeltaG is maximal at C(p) between 1 and 6 mg/ml), type of proteins, and their preparation technique. 相似文献
3.
Vladimir Bershtein Vladimir Gun'ko Larisa Egorova Natalia Guzenko Eugene Pakhlov Valery Ryzhov Vladimir Zarko 《Macromolecular Symposia》2010,296(1):541-549
Interfacial interactions and dynamics were studied in silica and alumina core-poly(vinyl pyrrolidone) (PVP) shell nanoparticles with different shell thicknesses starting from 1-2 nm (monolayer); their geometry and structural organization were comprehensively characterized by several techniques. Far- and mid-IR spectroscopy, combined with DSC activation analysis of the glass transition, allowed to register hydrogen bonding and Lewis/Brønsted interactions, and the multi-modal glass transition dynamics in PVP nanoshells, as well as their interrelationship. For PVP monolayer, only a few “abnormal” modes constituted glass transition which covered the temperature range from 80 to 230 °C, with varying the activation energy by an order of magnitude. 相似文献
4.
A new heterogeneous catalyst composed of copper and nickel oxide particles supported within charcoal has been developed. It catalyzes cross-couplings that traditionally use palladium, nickel, or copper, including Suzuki-Miyaura reactions, Buchwald-Hartwig aminations, vinylalane alkylations, etherifications of aryl halides, aryl halide reductions, asymmetric conjugate reductions of activated olefins, and azide-alkyne "click" reactions. 相似文献
5.
Anna A. Rugal Vladimir M. Gun’ko Valentina N. Barvinchenko Vladimir V. Turov Tatyana V. Semeshkina Vladimir I. Zarko 《Central European Journal of Chemistry》2007,5(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 < 265 K), adsorption, 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 < 273 K) because of coagulation of HPF molecules. Addition of nanosilica to the HPF solution strongly reduces the amounts
of structured water because of adsorption interaction of HPF molecules with silica nanoparticles, self-association of HPF
molecules, formation of denser packed hybrid agglomerates with HPF and silica, and lastly, because of conformational changes
of HPF. A monolayer adsorption capacity of A-300 corresponds to 156 mg of HPF per gram of silica. The 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.
相似文献
6.
Behaviour of pure water and water mixture with benzene or chloroform adsorbed onto ordered mesoporous silicas 总被引:1,自引:0,他引:1
Vladimir M. Gun’ko Vladimir V. Turov Alexander V. Turov Vladimir I. Zarko Vasiliy I. Gerda Victor V. Yanishpolskii Inna S. Berezovska Valentin A. Tertykh 《Central European Journal of Chemistry》2007,5(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.
Former address: Pisarzhevskii Institute of Physical Chemistry, 31 Prospect Nauki, Kiev, Ukraine 相似文献
7.
V. I. Zarko 《Theoretical and Experimental Chemistry》1999,35(4):238-241
We show that in the transition from Ti(IV) to Ti(III), on the surface of anatase the TiO6/3 octahedra undergo compressive tetragonal distortion. The axial Ti−O bond length in the octahedron decreases in this case
by at least 0.0027 nm.
Institute of Surface Chemistry, National Academy of Sciences of Ukraine, 31 Prospekt Nauki, Kiev 252022, Ukraine. Translated
from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 4, pp. 253–256, July–August, 1999. 相似文献
8.
Gun'ko VM Blitz JP Zarko VI Turov VV Pakhlov EM Oranska OI Goncharuk EV Gornikov YI Sergeev VS Kulik TV Palyanytsya BB Samala RK 《Journal of colloid and interface science》2009,330(1):125-137
Morphological, structural, adsorption, and catalytic properties of highly disperse titania prepared using sulfate and pyrogenic methods, and fumed titania-containing mixed oxides, were studied using XRD, TG/DTA, nitrogen adsorption, (1)H NMR, FTIR, microcalorimetry on immersion of oxides in water and decane, thermally stimulated depolarization current (TSDC) and catalytic photodecomposition of methylene blue (MB). Phase composition and aggregation characteristics of nanoparticles (pore size distribution) of sulfate and pyrogenically prepared titania are very different; temperature dependent structural properties are thus very different. Catalytic activity for the photodecomposition of MB is greatest (per gram of TiO(2) for the pure oxide materials) for non-treated ultrafine titania PC-500, which has the largest S(BET) value and smallest particle size of the materials studied. However, this activity calculated per m(2) is higher for PC-105, possessing a much smaller S(BET) value than PC-500. The activity per unit surface area of titania is greatest for the fumed silica-titania mixed oxide ST20. Calcination of PC-500 at 650 degrees C leads to enhancement of anatase content and catalytic activity, but heating at 800 and 900 degrees C lowers the anatase content (since rutile appears) and diminishes catalytic activity, as well as the specific surface area because of nanoparticle sintering. 相似文献
9.
Gun'ko V. M. Zarko V. I. Turov V. V Goncharuk E. V. Voronin E. F. Kazakova O. A. 《Theoretical and Experimental Chemistry》2001,37(2):75-79
The effect of the adsorption of polyvinylpyrrolidone on the surface of highly dispersed silica on the state of interfacial water was studied by 1H NMR spectroscopy and thermally stimulated depolarization with freezing out of the bulk water. 相似文献
10.
L. G. Grechko V. I. Zarko G. M. Kozub V. V. Motrich A. A. Chuiko 《Theoretical and Experimental Chemistry》1989,24(5):593-596
The dielectric characteristics of pyrogenic silicon dioxide were measured, and a theoretical analysis of the change of the dielectric properties of pyrogenic silicon dioxide was carried out with due regard for the surface conduction of water on its particles. A model of a two-layer particle was chosen as the theoretical model. It was shown that the choice of such a model makes it possible to explain experimentally the relaxation maximums of the dielectric losses observed in the frequency range 105–107 Hz.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 5, pp. 619–622, September–October, 1988. 相似文献