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Gun'ko V.M.,Chuiko Institute of Surface Chemistry General | Turov V.V.,Chuiko Institute of Surface Chemistry General | Krupska T.V.,Chuiko Institute of Surface Chemistry General | Tsapko M.D.,Taras Shevchenko National University | And 3 more authors.
RSC Advances

The effects of changes in the hydration degree of lactic acid bacteria (LAB), dispersion media composition and interactions with silica TS 100 and silylated silica gel Sipernat 50 were analysed using 1H NMR and DSC methods. Several types of water were found in wetted LAB. There were strongly and weakly bound waters determined from their changes in the Gibbs free energy. Strongly and weakly associated waters were identified by changes in the chemical shifts of the proton resonance for hydroxyls participating in hydrogen bonds. Changes in the characteristics of water bound to LAB depend on the water content, dispersion medium and co-adsorbate types, and the presence of silica. In DSC thermograms, changes in the values of enthalpy for exotherms (upon cooling) and endotherms (upon heating) per gram of bound water were much lower than that for bulk water because of the freezing point depression characteristic for bound water, which, therefore, could not form ice crystallites. © 2015 The Royal Society of Chemistry. Source

Davydenko L.,Chuiko Institute of Surface Chemistry General | Mischanchuk B.,Chuiko Institute of Surface Chemistry General | Pokrovskiy V.,Chuiko Institute of Surface Chemistry General | Babich I.,University of Twente | Plyuto Y.,Chuiko Institute of Surface Chemistry General
Chemical Vapor Deposition

The mechanism of CVD of Cr(acac)3 molecules at active sites on the surface of silica and alumina supports is studied by infrared (IR) spectroscopy and temperature programmed desorption mass spectrometry (TPD-MS). TPD-MS patterns of the molecular acetylacetone [H3CCOCH 2COCH3]+• (m/z 100), as well as the fragment ions [H3CCOCH2CO]+ (m/z 85) and [H3CCO]+ (m/z 43), are monitored to study the interaction of acetylacetonate ligands with the support surface upon thermal treatment. It is found that surface hydroxyl groups are responsible for the binding of Cr(acac)3 molecules, only in the case of the silica support, due to hydrogen bonding (H-bonding) with the acetylacetonate ligand. The TPD-MS of Cr(acac)3/SiO2 exhibits the pattern of the molecular ion (m/z 100) in the range 400 - 600 K, which means the release of Hacac molecules, originating from Cr(acac)3 molecules, H-bonded to surface hydroxyl groups. In contrast, the binding of Cr(acac)3 molecules at the alumina surface is due to electron donor-acceptor interaction of acetylacetonate ligands with Al3+ sites. The TPD-MS of Cr(acac)3/Al 2O3 exhibits mainly the fragment ion [H 3CCO]+ (m/z 43) within the range 400 - 750 K, and only negligible intensity of the molecular ion (m/z 100) in the range 400 - 600 K. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Ivanov A.E.,Protista Biotechnology AB | Kozynchenko O.P.,JAYS | Mikhalovska L.I.,University of Brighton | Tennison S.R.,JAYS | And 5 more authors.
Physical Chemistry Chemical Physics

Adsorption of myoglobin (Mb), bovine serum albumin (BSA) and γ-globulin (GG) onto activated carbons (ACs) with different pore size distributions, and poly(vinyl alcohol) (PVA) monolithic cryogels containing AC particles was studied. The highest initial rate of Mb adsorption was observed for AC having the largest specific surface area (1939 m2 g -1) and pore volume (1.82 cm3 g-1). The adsorption kinetics of proteins was characterized by a bimodal shape of the distribution f(D) function of an effective diffusion coefficient. Adsorption isotherms of Mb and GG were of Freundlich type within the studied range of equilibrium concentrations (10-150 μg mL-1). The distributions of free energy of protein adsorption were bimodal and reflected both interactions with carbon surfaces and self-association of proteins. Adsorbed amounts of Mb were the highest among the proteins studied (up to 700 mg g-1 carbon), which was attributed to the higher fraction of pores accessible for Mb. Incorporation of carbon particles into PVA-based cryogel resulted in macroporous monolithic composite materials (AC-PVA) exhibiting good flow-through properties. Scanning electron microscopy of the composites showed macroporous aggregates of carbon particles held together by films and bridges of PVA. The rates of adsorption and adsorbed amounts of proteins on AC-PVA were reduced compared to the pristine carbon and depended on the carbon content in the composites. Nevertheless, adsorption of Mb on AC-PVA took place even in the presence of 500-fold higher concentration of BSA. This indicated a possibility of Mb clearance from blood plasma using the PVA-carbon monoliths. © 2012 the Owner Societies. Source

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