Cellular adhesion and proliferation on poly(3,4-ethylenedioxythiophene): Benefits in the electroactivity of the conducting polymer

Cell adhesion and proliferation in poly(3,4-ethylenedioxythiophene), an electroactive polythiophene derivative generated by anodic polymerization, has been investigated. Results show that epithelial cells Hep-2 present significant activity on the surface of poly(3,4-ethylenedioxythiophene) electrodeposited on stainless steel electrodes, no sign of cytotoxicity being detected for this conducting polymer. Indeed, seeded and cultured cells bound better to poly(3,4-ethylenedioxythiophene) than to uncoated stainless steel, the latter substrate being used as a control. Furthermore, the electrochemical characteristics of poly(3,4-ethylenedioxythiophene) covered with cells was determined in different biological media using cyclic voltammetry experiments. Results reveal a significant increase in the electroactivity of this material when it is covered with a cellular monolayer. The overall of the results evidences not only the biocompatibility of poly(3,4-ethylenedioxythiophene) with Hep-2 cells but also their electrocompatibility.     

k0-measurements and related nuclear data compilation for (n, γ) reactor neutron activation analysis

Recommended k₀-factors and related nuclear data for use in (n, γ) activation analysis are given for 72 isotopes. In addition the basic nuclear constants and experimental parameters needed in the k₀ standardization method are reviewed. For convenient data reduction, computer programs were developed.     

Synthesis,reactions and catalytic activity of some mixed trifluorophosphine(triphenylphosphine)hydrido complexes of cobalt(I)

The complexes CoH(PF₃)_4?n (PPh₃)_n (n = 1–3) have been prepared by low from the reaction between CoH(PF₃)(PPh₃)₃ and butadiene. The hydrido complexes are active catalysts for the isomerisation of 1-octene to 2-octene under hydrogen or nitrogen.     

1,2-oxazine chemistry—II : The crystal and molecular structure of N-(p-carboxybenzyl)-tetrahydro-1,2-oxazine

The crystal structure of the title compound has been determined from X-ray diffractometer data by direct methods, and refined by full matrix least squares techniques to R = 0·057 for 1231 reflections. The crystals are monoclinic, space group C2/C, cell dimensions a = 1665, b = 987, c = 1443 pm, β = 107·37° and Z = 8. The conformation of the tetrahydro-1,2-oxazine ring is a chair with the N-substituent equatorial. There is evidence of significantly greater torsional angles around the N and O atoms than around the ring C atoms, showing the ring to be more puckered than cyclohexane. The hydrogen bond is between the acid group on one molecule and the ring nitrogen on its neighbour.     

The effect of metal oxides on the oxidation of polybutadiene

Carboxy-terminated polybutadiene (CTPB) was oxidised as a coating on various metal oxides by heating in air on a thermobalance. The oxidation was found to be free from diffusion control and was catalysed by certain of the oxides. The catalysis was shown to be independent of semiconductor type and to be associated with those oxides for which the width of the forbidden zone between the valence and conduction bands (U) is less than 1.9 eV. In general, low values of U result in high catalytic activity. It is proposed that catalysis occurs by a redox mechanism, viz. RO₂H + p → RO₂^. + H⁺, RO₂H + e → RO^. + OH^?.     

Structure and extinction of counterflow diffusion flames above condensed fuels: Comparison between poly(methyl methacrylate) and its liquid monomer,both burning in nitrogen–air mixtures

Since poly(methyl methacrylate) is known to depolymerize largely to its monomer when heated, the chemical kinetics in the gaseous diffusion flame produced by this polymer in a fire may coincide with that of burning liquid methyl methacrylate. To test this hypothesis, flat diffusion flames were probed and extinguished adjacent to surfaces of each of these fuels. Profiles of temperature and of concentrations of stable chemical species are reported, as are gas velocities of approach flow required to produce extinction for various oxygen/nitrogen ratios of the stream. Results revealed structural differences attributable to differing thermal properties of the fuels. Many fuel species were observed in the gas phase, their profiles being partially rationalized on the basis of a suggested decomposition mechanism for gaseous methyl methacrylate. Overall kinetic parameters for gasphase combustion, obtained by use of extinction results in a previously developed theory, are nearly the same for the polymer and monomer but appear to differ by amounts exceeding experimental uncertainties. It is suggested that this may be traced to small differences in fuel species leaving the condensed phase which, for the polymer, is covered by a thin, two-phase region.     

Imidazopyeidine derivatives as polymethine dyes

Several new polymethine dyes of the cyanine and merocyanine series with 1-methyl-1H-imidazo [4,5-b]pyridine residues were synthesized, and their colors were studied. Replacement of the benzimidazole residue in the cyanine dyes by a l-methyl-1H-imidazo[4,5-b]-pyridine residue leads to deepening of the dye color.See [1] for communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1561–1565, November, 1971.     

Nα,Nim-di-tert-alkoxycarbonyl derivatives of histidine

The acylation of histidine with di-tert-butyl and di-tert-amyl pyrocarbonates has given the corresponding N,N_im-di-tert-alkoxycarbonyl derivatives. The N,N^im-di-tert-butoxycarbonyl derivative was obtained in the crystalline form by crystallization from benzene or carbon tetrachloride, or in the form of salts with cyclohexylamine, dicyclohexylamine, and diethylamine. N,N^im-di-tert-amyloxycarbonyl-histidine was characterized in the form of the salt with dicyclohexylamine.Institute of Biological and Medicinal Chemistry, Academy of Medical Sciences of the USSR, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 379–383, May–June, 1980.     

Spectrophotometric determination of rhenium with di(2-pyridyl)ketone-2-furancarbothiohydrazone and other thiohydrazones

A simple rapid method is proposed for the determination of rhenium (as perrhenate) in which the brown-violet complex produced is measured at 546 nm. The system obeys Beer's law in the range 0.7–14.0 μg Re ml^-1; the molar absorptivity is 1.51 × 10⁴ l mol^-1 cm^-1 in ethanol and 1.64 × 10⁴ l mol^-1 cm^-1 for the complex extracted into methyl isobutyl ketone. Molybdenum (100-fold), tungsten (40-fold), copper (10-fold), and palladium (10-fold) are tolerable. Reactions of other metal ions such as Cu(II), Ni(II), Co(II) and Fe(II) with this ligand and reactions of perrhenate with analogous reagents are discussed.