Immobilization of α-amylase in vinyl-polymer-based interpenetrating polymer networks

Semi-interpenetrating polymer networks (IPNs) of poly(ethylene glycol), poly(vinyl alcohol) and polyacrylamide were prepared as a support for enzyme immobilization and kinetic studies were performed for the immobilization of -amylase. The effect of IPN composition on the extent of immobilization was investigated and the percentage of relative activity of the immobilized enzyme was evaluated as a function of the chemical architecture of the IPNs, pH and temperature, taking starch as a substrate. The kinetic constants and the maximum reaction velocity were also evaluated. The IPNs were characterized by IR spectral analysis.     

The viscosity and density of the methanol + n-nonane, ethanol + n-nonane, and ethanol + n-decane systems

This work presents the results obtained in measurements of the kinematic viscosity and density of the methanol-n-nonane, ethanol-n-nonane, and ethanol-n-decane systems at various temperatures and low n-alkane concentrations (within the concentration range of miscibility). The dynamic viscosities of these systems at 298.15 K were calculated according to free volume theory. The results substantiated the existence of an anomaly in the behavior of viscosity of the methanol-n-nonane system (positive Δlnη values) and its absence for the ethanol-n-alkane systems.     

Kinetics of the reaction of 4-nitrophenyl benzoates with 4-chlorophenol in the presence of potassium carbonate in dimethylformamide

The effect of the substituent in the benzoyl group on the relative rate and activation parameters of transesterification of substituted 4-nitrophenyl benzoates with 4-chlorophenol in dimethylformamide in the presence of potassium carbonate was studied by the competing reaction technique. The whole series of benzoates showed the enthalpy-entropy compensation effect. 4-Nitrophenyl benzoates having electronacceptor substituents give rise to isokinetic relationship with an isokinetic temperature β of 382 K. The mechanism of the transesterification process is discussed.     

Preparation of ultramicro-, micro-, and supermicroporous carbon adsorbents by template procedure

The new template procedure for preparing ultramicro-, micro-, and supermicroporous carbon adsorbents is proposed on the basis of the use of two polymers with different thermal stabilities as a template matrix and a carbonizable carbon source. The polymeric template matrix is removed by thermal decomposition in the low-temperature pyrolysis of the polymer mixture, whereas the second polymer component of a mixture is transformed into a carbonizate. The resultant monolithic carbonizate is the polymeric matrix replica and represents a molecular-sieve ultramicroporous carbon adsorbent, which adsorbs water vapor at 293 K and does not adsorb nitrogen vapor at 77 K. The activation of this carbonizate with water vapor leads to a series of micro-and supermicroporous carbon adsorbents with a broad range of the parameters of a pore structure: BET specific surface area S _BET is 610–2130 m²/g, micropore volume W ₀ is 0.20–0.69 cm³/g, micropore half-width x ₀ (slit model) is 0.20–0.70 nm, mesopore specific area S _me is 20–1000 m²/g, and characteristic adsorption energy E ₀ is 15.6–27.4 kJ/mol. Original Russian Text ? O.K. Krasil’nikova, A.M. Voloshchuk, A.E. Evsyukhin, N.Y. Lomovsakaya, 2006, published in Kolloidnyi Zhurnal, 2006, Vol. 68, No. 2, pp. 207–213.     

Structure and heat-induced transformations of phosphorus-doped polyantimonic acids

X-ray powder diffraction and thermogravimetry (TG) are used to study the solid compounds formed upon joint hydrolysis of antimony pentachloride and phosphoric acid in the molar ratio range of 1.35 < Sb/P < 12. The products retain the pyrochlore structure motif intrinsic to crystalline polyantimonic acid, the increasing phosphorus concentration deteriorates the degree of crystallinity of the products. Contributions of various factors into diffraction peak broadening are ascertained. The effect of phosphorus on the structure of the products is discussed on the basis of X-ray powder diffraction and TG data.     

Thermally Curable Emulsion Binders for Mold Cores and Molds Based on Tall Pitch

Preparation of thermally curable emulsion binders for mold cores and molds using tall pitch was studied. Preparation conditions, composition, and colloid-chemical properties of the resulting emulsions were investigated.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005, pp. 292–296.Original Russian Text Copyright © 2005 by A. Radbil’, Ismagilov, B. Radbil’.     

Synthesis and transformations of metallacycles 33. The first example of cycloalumination of cyclonona-1,2-diene with Et<Subscript>3</Subscript>Al and EtAlCl<Subscript>2</Subscript> in the presence of Cp<Subscript>2</Subscript>ZrCl<Subscript>2</Subscript>

Catalytic cycloalumination of cyclonona-1,2-diene upon treatment with Et₃Al and EtAlCl₂ in the presence of Cp₂ZrCl₂, leading to 10-ethyl-10-aluminabicyclo[7.3.0^1,9]dodec-8-ene (1) and 11-ethyl-11-aluminatricyclo[10.7.0^1,12.0^2,10]nonadeca-9,12-diene, respectively, was accomplished in high yields. A possibility for the selective transformation of compound 1 to 1-allyl-9-(pent-4-enyl)cyclonon-1-ene and 10-hydroxybicyclo[7.3.0^1,9]dodec-8-ene in one preparative step was demonstrated. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2156–2159, November, 2007.     

Molecular Structure of Bis(trimethylsilyl) Hypophosphite HP(OSiMe3)2 by Gas-Phase Electron Diffraction and Quantum Chemistry

Geometric parameters and conformation of the bis(trimethylsilyl)hypophosphite molecule were determined by gas-phase electron diffraction and quantum-chemical calculations. The molecule has an asymmetric structure, including an asymmetric P(OSiMe₃)₂ group. The principal geometric parameters are as follows: (r _a; in parentheses are standard deviations): bond lengths: P-O 1.616 and 1.633(1), Si-O 1.670(1), Si-C 1.892(1), C-H 1.097(3) Å; bond angles: OPO 100.8(8), POSi 133.3, and 138.4(3)°; torsion angles about P-O bonds 120(2) and 41.(3)°; and torsion angles about Si-O bonds are 145 and −178(4)°.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 6, 2005, pp. 897–902.Original Russian Text Copyright © 2005 by Naumov, Oberhammer, Tafipol’skii.     

Synthesis and structure of optically active compounds [Ni(HL1)]NO3 and [Ni(HL2)]NO3H2O containing anions of diaminodioximes H2L1 and H2L2 derived from α-Pinene and (+)-3-Carene as Ligands

New optically active levorotatory compounds [Ni(HL¹)]NO₃ (I) and [Ni(HL²)]NO₃H₂O (II) containing the anions of chiral diaminodioximes, H₂L¹ and H₂L², derived from the terpenes ±-pinene and (+)-3-carene, respectively, were synthesized. Complexes I and II were studied by X-ray diffraction. The crystal structures of compounds are ionic, being composed of the [Ni(HL¹)]⁺ or [Ni(HL²)]⁺ cations and the outer-sphere NO₃^– anions. The Ni²⁺ ion coordinates four N atoms of the tetradentate chelating ligand, the NiN₄ coordination unit being shaped like a tetrahedrally distorted square. Compounds I and II are diamagnetic, which corresponds to a low-spin d⁸ configuration. The NMR spectra of compounds were recorded and analyzed.Translated from Koordinatsionnaya Khimiya, Vol. 30, No. 12, 2004, pp. 888–896.Original Russian Text Copyright © 2004 by Larionov, Myachina, Saveleva, Glinskaya, Klevtsova, Sheludyakova, Tkachev, Bizyaev.     

Determination of trace and platinum-group elements in high ionic-strength volcanic fluids by sector-field inductively coupled plasma mass spectrometry (ICP-MS)

The accurate measurement of ultra-trace concentrations of rare metals and platinum group elements in volcanic fluids is complicated by interferences, complex matrices, and preferential element partitioning. We analyzed condensed, high-temperature magmatic fluids collected from Kudryavy volcano (Kurile Islands, Russia) for Be, B, Rb, Sr, Mo, Ru, Rh, Pd, Cd, W, Re, Pt, Pb, Bi, and U using ICP-MS. The samples had three different matrices: 5 mol L^–1 sodium hydroxide (NaOH, pH = 11), gas condensates of sulfuric acid (H₂SO₄, pH = 0), and solid elemental sulfur. Interferences and suppression/enhancement effects were investigated using standards in concentrated NaOH and H₂SO₄ solutions to determine adequate dilution for sample analyses, which then required very low levels of element detection (< 1 μg L^–1 for most elements). Depending on the field sampling technique of volcanic gas vents, our results show significant differences in concentrations of some trace elements due to the precipitation of solid sulfur during gas condensation and variations in element volatility as a function of temperature.