Decrease in Content of Insoluble Fraction in <Emphasis Type="Italic">cis</Emphasis>-1,4-Polyisoprene in Formation of Titanium Catalyst in Turbulent Flow

The effect caused by using a tubular prereactor of the diffuser-confuser design operating in the turbulent flow mode on the content of the insoluble gel fraction in cis-1,4-polyisoprene obtained on a Ti/Al catalyst is studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 5, 2005, pp. 779–782.Original Russian Text Copyright © 2005 by Zakharov, Berlin, Monakov.     

New Stationary Phases for Normal-Phase HPLC Based on Silica Gel Modified with Magnesium,Calcium, Strontium,and Barium Salts

Several new stationary phases for normal-phase high-performance liquid chromatography were synthesized by the modification of silica gel with magnesium, calcium, strontium, and barium salts and subsequent calcination at 700°C. These sorbents exhibit an increase in the retention of organic compounds of the basic character, an increase in the selectivity of separation, and a threefold increase in efficiency in comparison with the initial silica gel. The experimental results were explained on the basis of the interpretation of the IR spectra of pyridine adsorbed on the synthesized and initial silica gels.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 8, 2005, pp. 842–847.Original Russian Text Copyright © 2005 by Pirogov, Kuzavlev, Shpigun.     

New stationary phases for normal-phase HPLC based on silica gel modified with cobalt,nickel, zinc,and cadmium salts

Several new stationary phases for normal-phase high-performance liquid chromatography were synthesized by the modification of silica gel with cobalt, nickel, zinc, and cadmium salts and subsequent calcination at 700°C. These sorbents exhibit an increase in the retention of organic compounds of the basic character, an increase in the selectivity of separation, and an eightfold increase in efficiency in comparison with initial silica gel. The experimental results were explained on the basis of the interpretation of the IR spectra of pyridine adsorbed on the synthesized and initial silica gel. It was demonstrated that the surface of silica gel modified with cadmium ions exhibits the highest acidity. The advantage of the synthesized sorbents was demonstrated with the example of the separation of fullerenes containing diethylamino and hydroxy groups.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 4, 2005, pp. 412–416.Original Russian Text Copyright © 2005 by Pirogov, Kuzavlev, Shpigun.     

Physicochemical and Sorption Properties of Silica Gel with Immobilized Xylenol Orange Surface Groups

Organomineral sorbents were prepared by sorption immobilization of Xylenol Orange on the surface of two different samples of silica gel from aqueous solutions with pH 1.68 under static conditions. The diffusion coefficients of Xylenol Organe in the near-surface layer of silica gel and the equilibrium sorption constants were determined. Wash-out of the dye from the sorbent was studied. Sorption of Cu(II), Zn(II), and Pb(II) on the sorbents from aqueous solutions with pH 5.8 was studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 1, 2005, pp. 73–78.Original Russian Text Copyright © 2005 by Korneev, Kholin.     

Classification and Principles of Planar Chromatography in Test Methods of Chemical Analysis

The test methods of chemical analysis with the use of various versions of planar chromatography are considered. Cellulose paper and thin silica gel layers on polymer supports are used as stationary-phase carriers. The test solution serves as a mobile phase. The length of a colored or decolorized zone in test strips (laminated in a transparent polymer film) obtained by contact with the test solution through a small orifice or slot in the film serves as an analytical signal. Planar chromatography in the test methods of chemical analysis is classified in accordance with the mechanism of interactions between the mobile and stationary phases: precipitation, acid-base (proton-exchange), chemisorption, complexation, redox (electron-exchange), catalytic, and adsorption chromatography. Examples of stationary phases and particular analytical applications are given.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 8, 2005, pp. 869–876.Original Russian Text Copyright © 2005 by Amelin.     

Impedance spectra analysis of thermoresponsive poly(acryloyl‐L‐proline methyl ester) gel membrane in LiCl solution

Impedance spectra analysis of a thermoresponsive poly(acryloyl‐L ‐proline methyl ester) (poly(A‐ProOMe)) hydrogel membranes in an aqueous solution of LiCl was carried out using a simple equivalent model. The hydrogel membrane was synthesized by γ‐radiation‐induced polymerization and crosslinking of A‐ProOMe monomer aqueous solution in a glass‐cast. By means of the impedance spectra analysis, a novel method for the calculation of the ionic conductivity of the hydrogel membranes in LiCl solution was proposed. The calculated ionic conductivity was in agreement with the determined value. In addition, effects of temperature and LiCl concentration on the impedance spectra and ionic conductivity of the gel membrane were analyzed. Results indicated that the impedance spectra analysis is a very useful tool for evaluating the electric properties of gel membranes in an electrolyte solution. The poly (A‐ProOMe) gel membrane in 1.0 M LiCl solution showed a high ionic conductivity of about 0.2 S/cm at 14 °C. The temperature‐dependence of the ionic conductivity was a complex nonlinear form due to the volume phase transition of the thermoresponsive poly(A‐ProOMe) gel membrane, and the volume phase transition temperature appeared to be decreased with the increase in the LiCl concentration. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2843–2851, 2005     

Determination of particle size in aqueous suspensions of hydrogels of iron(III), indium(III), aluminum, chromium(III), titanium(IV), and zirconium(IV) oxohydroxides

Dispersion of hydrogels of Fe^III, In^III, Al^III, Cr^III, Ti^IV, and Zr^IV oxohydroxides in an aqueous medium was studied by sedimentation analysis. The hydrogel dispersion depends on the metal nature, pH of precipitation, and suspension concentration. The systems are predominantly polydisperse, and the gel particle size ranges from 2 to 140 μm. The data obtained suggest that the gel particles are formed by three-dimensional networks consisting of polymeric chains metal-oxygen and contain cavities filled with water. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1083–1088, May, 2005.     

Separation of homologues of organic compounds using the gradient of the eluent flow rate on a monolithic porous column

The use of the gradient of the eluent flow rate is proposed for the optimization of separation in high-performance liquid chromatography (HPLC). This approach was used for the separation of the homologues of polycyclic aromatic compounds and di-n-alkyl phthalates on monolithic porous silica gel Chromolith (Merck, Germany) with modifying octadecyl radicals by reversed-phase HPLC. The principle of the optimization of the gradient of the eluent flow rate for the separation of the homologues of organic compounds was formulated on the basis of peculiarities in their chromatographic retention. It was demonstrated that using the gradient of the flow rate provides the selective and efficient separation of homologues and a significant decrease in the time of separation.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 4, 2005, pp. 398–403.Original Russian Text Copyright © 2005 by Nesterenko, Rybalko.     

Synthesis of poly(vinylidene fluoride) (PVdF)/silica hybrids having interpenetrating polymer network structure by using crystallization between PVdF chains

High transparent and homogeneous poly(vinylidene fluoride) (PVdF)/silica hybrids were obtained by using an in‐situ interpenetrating polymer network (IPN) method. The simultaneous formation of PVdF gel resulting from the physical cross‐linking and silica gel from sol–gel process prevented the aggregation of PVdF in silica gel matrix. To form the physical cross‐linking between PVdF chains, the cosolvent system of dimethylformaide (DMF) and γ‐butyrolactone was used. The obtained PVdF/silica hybrids had an entangled combination of physical PVdF gel and silica gel, which was called a “complete‐ IPN” structure. The physical cross‐linking between PVdF chains in silica gel matrix was confirmed by differential scanning calorimetry (DSC) measurements. The miscibility between PVdF and silica phase was examined by scanning electron microscopy (SEM) and tapping mode atomic force microscopy (TM‐AFM) measurements. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3543–3550, 2005     

Synthesis of polyacrylamide gel beads with electrostatic functional groups for the molecular imprinting of bovine serum albumin

Synthetic materials capable of recognizing proteins are important in separation, biosensors and biomaterials. In this study, bovine serum albumin-imprinted soft-wet polyacrylamide gel beads were prepared via inverse-phase suspension polymerization, using acrylamide and N,N′-methylene diacrylamide as polymeric matrix components and methacrylic acid as functional monomer. The adsorption study showed, through the imprinting process, that the imprinted gel beads had much higher adsorption capacity than the nonimprinted gel beads, and that the matching of the surface zeta-potential between the templates and the imprinted gel beads can enhance the imprinting effect. Adsorption kinetics indicated that the adsorption process could be described as an apparent first-order kinetic process for the gel beads. From the adsorption isotherm curve, we found that the adsorption of the imprinted gel beads was in agreement with the Langmuir adsorption model. Moreover, selectivity testing of the imprinted gel beads showed that imprinted gel beads exhibited good recognition for BSA as compared to the control protein. We speculate that the formation of complementary shapes and multiple-point electrostatic interactions between the imprinting cavities and the template proteins are the two factors that lead to the imprinting effect.      

Pyrolysis study of sol-gel derived TiO2 powders: Part IV. TiO2-anatase prepared by hydrolysing titanium(IV) isopropoxide without chelating agents

An amorphous TiO₂ gel was obtained by hydrolysing titanium(IV) isopropoxide with a stoichiometric amount of water using SnCl₂ as catalyst. In these operative conditions, a TiO₂ gel matrix containing a lower fraction of organic residual was obtained with respect to samples prepared by previously modifying the titanium alkoxide precursor with chelating ligands. Dried gel powders were characterized by N₂ adsorption analyses, FT-IR and XRD measurements. Thermogravimetric (TG) and differential thermal analysis (DTA) coupled with mass spectrometric (MS) and gas chromatographic (GC) measurements were performed in order to identify the organic products released from TiO₂ gel pyrolysis. The Tg-MS semiquantitative analysis of the main evolved species allowed to describe both the chemical composition of the initial TiO₂ gel and the chemical rearrangements occurring in the matrix during heating up to its crystallisation to anatase form at 420°C.This revised version was published online in November 2005 with corrections to the Cover Date.     

Vanadium levels in marine organisms of Onagawa Bay in Japan

Vanadium in marine organisms from Onagawa Bay in Miyagi, Japan, was determined by an instrumental neutron activation analysis (INAA) method using anti-coincidence gamma-ray spectrometry at the Dalhousie University SLOWPOKE-2 Reactor (DUSR) facility in Canada. Seaweeds, cultivated oysters, plankton, and four different species of sea squirt were collected from Onagawa Bay during 2005–2008. Vanadium levels around 20 μg g⁻¹ (dry weight) were found in Japanese tangle and hijiki seaweeds. One species of sea squirt (Ciona savignyi) contained 160–500 ppm of V and it was highest among the four species of sea squirts studied. Protein-bound V species were separated by gel permeation chromatography (GPC) and the element determined by inductively coupled plasma atomic emission spectrometry (ICP-AES).     

Thermal Behaviour of a TiO2—ZrO2 Microcomposite Prepared by Chemical Coating

A microcomposite powder in the system TiO₂—ZrO₂ as a precursor of zirconium titanate (ZT) materials has been studied by thermal methods (DTA-TG) and X-ray diffraction (XRD). The microcomposite powder has been prepared by chemical processing of crystalline TiO₂ (rutile, 10 mass% anatase),as inner core, coated with in situ precipitated amorphous hydrated zirconia gel, asouter core. The morphology and chemical composition of the resultant powders has been examined by SEM-EDX (Scanning electron microscopy-energy dispersive X-ray spectroscopy). Thermal behaviour of the microcomposite powder was reported, showing the dehydration and dehydroxylation of the zirconia gel, the crystallization into metastable cubic/tetragonal zirconia at temperatures 400—470°C, and the feasibility of preparing ZT powder materials by progressive reaction of TiO₂ and ZrO₂ at higher temperatures (1400°C).This revised version was published online in November 2005 with corrections to the Cover Date.     

Tobacco Peroxidase as a New Reagent for Amperometric Biosensors

The results of testing a new enzyme, anionic tobacco peroxidase (TOP), in various amperometric biosensors are summarized. The biochemical and electrochemical properties of the enzyme are briefly characterized. As compared to the commonly used cationic peroxidase from horseradish roots, TOP exhibits a wider optimum stability pH range, higher stability to inactivation with hydrogen peroxide, and higher efficiency in direct electron-transfer processes. The enzyme immobilized by adsorption on graphite is effective in determining aminophenols and aromatic diamines under flow conditions with a detection limit of 10 nM. Upon immobilization on graphite by incorporation into a gel of a redox-active polymer (crosslinked polyvinylimidazole with osmium 4,4′-dimethylbipyridinium chloride), TOP exhibited sensitivity and stability comparable to those of horseradish peroxidase and a wider linearity range. Upon immobilization on a self-assembled thiol monolayer at a gold electrode, TOP was much superior to horseradish peroxidase in the sensitivity of determining hydrogen peroxide, regardless of the charge of the monolayer. Prospects for the further use of the native enzyme and its genetically engineered unglycosylated form are considered.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 6, 2005, pp. 629–638.Original Russian Text Copyright © 2005 by Gazaryan, Gorton, Ruzgas, Csoregi, Schuhmann, Lagrimini, Khushpul’yan, Tishkov.Presented at the VI All-Russia Conference (with international participation) on Electrochemical Methods of Analysis (EMA-2004, Ufa, May 23–27, 2004).     

New synthetic methods for the formation of basic,polyvalent, hyperbranched grafts

A practical synthetic route to polybasic, polyamine, hyperbranched grafts using commercially available polyethyleneimine (PEI) and cyanuric chloride as a coupling agent is described. The grafting process was followed by XPS spectroscopy, TGA analysis, ATR‐IR spectroscopy, acid–base titration, and by ¹³C CP‐MAS NMR spectroscopy. In the case of silica gel, thermal gravimetric analyses showed that a 35 wt % loading of graft could be obtained. Acid–base titration of hyperbranched PEI grafts on silica gel and oxidized polyethylene powder showed the ion‐exchange capacities of these PEI‐grafted substrates were 1.00 and 0.17 mmol of base/g of solid, respectively. Although the focus of the paper is on grafting on silica gel, the influence of the kind of support and solvent on the grafting process and the ion‐exchange capacity was examined. Water was a good solvent for PEI grafting onto silica gel, but a more hydrophobic polyethylene support required the use of dichloromethane as a solvent for PEI graft synthesis. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4654–4665. 2005     

Catalytic conversions of chloroolefins over iron oxide nanoparticles 1. Isomerization of dichlorobutenes in the presence of iron oxide nanopaticles immobilized on silicas with different structures

The influence of the support nature and electronic state of iron oxide nanoclusters on the catalytic properties of supported systems was studied for dichlorobutene isomerization. A sample with a Fe content of 2.5 wt.% on the activated silica matrix containing Fe^III and Fe^II ions in the paramagnetic state exhibits the highest activity. The activity of iron on silica gel enhances with the appearance of magnetically ordered nanoclusters of γ-iron oxide formed at the iron content on the catalyst as high as 15 wt.%. An increase in the catalyst activity is favored by the formation of two states of iron (Fe^III and Fe^II) that occurs under the synthesis conditions or during the action of a reactant. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1376–1382, June, 2005.     

Experimental study of polyacrylamide gel in close‐in well operation

An optimized polymer gel, known as temporary gel, based on polyacrylamide sulfonated copolymer, and a chromium acetate hydroxide were synthesized to close‐in the wells during applying well servicing work. Based on bottle tests, polymer gel with 28 000 ppm of polymer concentration, and 0.105 ratio of crosslinker to polymer, was selected. The pressure effect within the range of 1000 to 4000 psi indicated not impressive effect of pressure on the gel properties. As the results of creep test clarified, yield strength of the gel was measured at temperature of 90°C, and 2000 Pa. Moreover, the results of an experiment under simulated well condition showed a linear correlation between the height of polymer gel column, and the strength and persistence of gel against fluid pressure. At last, process of degelling with 40 g of optimum gel was performed using 14 g of 30 wt% solution of citric acid during 4 hours.     

Diels–Alder reaction of anthracene on grafted polysiloxane and cylindrical carbosilane dendrimer

Anthracene‐grafted polysiloxane was prepared by the dehydrocoupling between linear siloxane polymers and anthracenecarbinol. The cylindrical type of dendritic polysiloxane was prepared up to the second generation by the hydrosilation between polysiloxane and vinyltrichlorosilane, and the continual addition of allyl alcohol. The anthracene groups on cylindrical dendrimers were prepared by the reaction of Si? Cl bonds on the polymer and anthracenecarbinol. The Diels–Alder reaction of anthracene moieties on polysiloxane and maleimide derivatives, maleic acid anhydride, and 1,4‐quinone derivatives was carried out under mild conditions. The polymers prepared were characterized by NMR and gel‐permeation chromatography. Copyright © 2005 John Wiley & Sons, Ltd.     

Conversion of Bicyclic C-Azoaziridines to 2-Substituted 2H-1,2,3-triazoles

In an acidified chloroform solution, bicyclic C-azo-N-(N-hetaryl)aziridines are converted to bicyclic 2H-1,2,3-triazoles. This transformation can occur on the surface of silica gel, and also during storage of these compounds at room temperature. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1573–1578, October, 2005.     

Copolymers of 2,5‐bis[(4‐methoxyphenyl) oxycarbonyl]styrene with n‐butyl acrylate: Design,synthesis, and characterization

A series of rod–coil diblock copolymers, consisting of poly{2,5‐bis[(4‐methoxyphenyl)oxycarbonyl]styrene} as a rigid segment and poly(n‐butyl acrylate) as a flexible part, were successfully prepared through two inverse procedures by atom transfer radical polymerization. The copolymers were characterized by ¹H NMR and gel permeation chromatography and had high molecular weights and relatively narrow polydispersities (polydispersity index < 1.20). All the block copolymers synthesized had two distinct glass‐transition temperatures according to differential scanning calorimetry. A polarizing optical microscopy investigation demonstrated the liquid crystallinity of the diblock copolymers. The self‐assembly behaviors in dilute solutions was studied by transmission electron microscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5935–5943, 2005