Monitoring of the Viability of Cells Immobilized by Sol-Gel Process

Three different types of cells, Pseudomonas fluorescens HK44, Saccharomyces cerevisiae strain SP4 and plant cells Nicotiana tabacum L. BY-2, were immobilized by entrapment in tetramethoxysilane prepolymer (TMOS) gel or in composite gel containing prepolymer TMOS and alginate in various ratios. Their growth and viability were monitored by bioluminescence and 2-D fluorescence spectra, which are fast and do not need the dissolution of a matrix. The resulting biocomposite gels were obtained by gelation of the mixtures of TMOS prep. or TMOS/alginate sols and the particular cells in proper media on glass supports to provide films ～1 mm thick. The effect of the following parameters on the growth and viability of the cells was studied: (a) the composition of the biocomposites, (b) the preparation conditions of TMOS and (c) the conditions of the procedure of entrapment. All three types of cells were tested in TMOS gel and the composite TMOS/alginate = 1:1 (v/v). The sensitivity of the cells to the changes of conditions increased in the sequence: P. fluorescence HK44 < S. cerevisiae strain SP4 < N. tabacum L. BY-2. Cell viability decreased with the increasing content of Si in biocomposites. The entrapment into alginate–silica composites resulted in the leakage of microbial and yeast cells. However, it had positive effects on the growth and metabolic activity of plant cells.     

A Robust and Efficient Method for the Computation of Equilibrium Composition in Gaseous Mixtures

This paper presents in detail a robust, efficient and accurate methodology for the computation of equilibrium composition in gaseous mixtures. The methodology is founded on the concept of the chemical basis, which is defined and formalized using a powerful matricial approach. The method is specially designed to be general, thus providing basic thermodynamic data in several areas, such as combustion, plasma chemistry and, more generally speaking, computational fluid dynamics. The performance of the method is given in terms of CPU usage and the computed results are compared with those in the published literature. The method is shown to yield results of very high quality in terms of accuracy and smoothness.     

Palladium-catalyzed carbon-carbon bond-forming 1,2-ligand migration of organoalanes

A one-pot, two-step process that transforms terminal alkynes into ethyl methyl-substituted benzylic quaternary carbon centers is described. (E)-2,2-Disubstituted-1-alkenyldimethylalanes have been shown to participate in 1,2-alkyl migration from aluminum to carbon with concomitant arylation at the 2-position to furnish ethyl methyl-substituted benzylic quaternary carbon centers, when reacted intramolecularly with aryl halides and triflates in the presence of a Pd(0) catalyst. The protocol is initiated with Cp2ZrCl2-catalyzed methylalumination of terminal alkynes followed by palladium-catalyzed intramolecular arylation of the resulting (E)-2,2-disubstituted-1-alkenyldimethylalanes, leading to 1,2-methyl shift from aluminum to carbon. In that sequence, a total of three new C-C single bonds are made, and two of the three alkyl groups on Me3Al transferred to the substrate on vicinal carbons. This method was applied to a variety of substrates, and the mechanism was investigated by deuterium-labeling experiments, which revealed that protodealumination of the final dialkylaluminum triflate or halide intermediates by CH3CN results in the formation of the fourth bond in the course of the transformation.     

Empirische Beziehungen zur Sauerstoffkoordination um Antimon(III) und Tellur(IV) in Antimoniten und Telluriten

The strong variability of bond length between Sb(III) or Te(IV) and oxygen is correlated with distances to more distant oxygen atoms in the trans position. Closer approach of the trans-oxygen atom leads to lengthening of the bond in question. Hyperbolic functions represent suitable approximations for the correlations and give the bond lengths on the average within 0.04 Å. The distance relations are discussed for various limiting coordinations corresponding to 3, 4, and 5.     

Hyperfine structure of six low-lying fine structure levels of191Ir and193Ir and the191Δ s 193 hyperfine anomaly

The hyperfine interaction constantsA andB of six low-lying metastable fine structure states of the two iridium isotopes¹⁹¹Ir and¹⁹³Ir and the electronicg-factors of these levels have been measured using the atomic-beam magnetic-resonance method. From the values of the magnetic-dipole interaction constantsA, corrected for off-diagonal perturbations, we extracted the hyperfine anomaly of a pure 6s-electron state:¹⁹¹ Δ _s ¹⁹³ =0.64(7)%. Using nonrelativistic approximations for the effective radial parameters the nuclear electric-quadrupole moments were obtained:Q(¹⁹¹Ir) = 0.81(21)b,Q(¹⁹³Ir)=0.73(19)b     

Square-Planar Nickel(II) O,O′-Dialkyldithiophosphato Complexes with Triphenylphosphine of the Type [NiX(S2P{OR}2)(PPh3)] (X = Cl,Br, I and NCS)

A series of new [NiX(S₂P{O-c-Hex}₂)(PPh₃)](X = Cl^–, Br^–, I^– and NCS^–)(1)–(4) and [Ni(NCS)(S₂P{OR}₂)(PPh₃)][R =n-Pr (5), i-Pr (6)] complexes has been synthesized and characterized by elemental analyses, f.i.r., i.r., u.v.–vis., ¹H-, ¹³C{¹H}- and ³¹P{¹H}-n.m.r. spectra, magnetochemical and conductivity measurements. A single crystal X-ray analysis of [Ni(NCS)(S₂P{O-n-Pr}₂)(PPh₃)](5) reveals the molecular structure of the complex and confirms a square-planar geometry around the central atom of nickel with the NCS anion coordinated via the nitrogen atom.     

Intercombination lines of Mg I-, Al I- and Si I-like ions in the beam foil spectra of Ti,Fe, Ni and Cu

In delayed spectra of foil-excited beams of Ti, Fe, Ni and Cu ions lines have been observed which are identified with intercombination transitions 3s ^{2 1} S ₀ — 3s 3p ³ P ₁ ⁰ , 3s ² 3p ² P ⁰ — 3s 3p ^{2 4} P and 3s ² 3p ^{2 3} P — 3s 3p ^{3 5} S ₂ ⁰ in magnesiumlike, aluminiumlike and siliconlike spectra, resp. Wavelengths and decay properties have been determined. The results are compared to recent theoretical predictions.