NMR-spektroskopische Untersuchungen zur Solvatation von Tetraphenylimidodiphosphatokomplexen der Lanthanoiden

NMR-spectroscopic Investigations on Solvation of Lanthanoide Complexes of Tetraphenylimidodiphosphate The additional coordination of solvent molecules to chelate complexes LnA₃ of rare earth ions (Ln³⁺) and tetraphenylimidodiphosphate ions (A^?) has been studied by ¹H-NMR spectroscopy. The nature of the solvent has a great influence on the spectra observed especially in the case of paramagnetic Ln³⁺ ions. In acetone as solvent TmA₃ forms a disolvate preferably. The brutto stability constants for the additional coordination of acetone as ligands by TmA₃ are β₁ = (0.013 ± 0.003) mol^?1 · l and β₂ = (0.016 ± 0.001) mol^?1 · l².     

Photochemical reactions. 140th Communication. Acid-catalyzed rearrangement and electron transfer photooxygenation of cyclopropanols and their silyl ethers

On acid-catalyzed hydrolysis, the tricyclic compounds 2 and 10 , incorporating cyclopropyl-silyl-ether moieties undergo rearrangement to the cis-decalones 3 and 7 , respectively. Hydrolysis of 2 and 10 in the presence of oxygen leads additionally to the formation of the 1,2-dioxolan-3-ols 9 and 13 , respectively, which involves an electron-transfer oxygenation process as could be demonstrated by photooxygenation of the silyl ether 10 and the cyclopropanol 14 in the presence of 9,10-dicyanoanthracene. The configurations of 3 and 9 were assigned by X-ray analysis of the latter compound as well as of the p-nitrobenzoate 8 of 3 .     

Glucose oxidase—hexokinase bienzyme electrode sensor for adenosine triphosphate

A bienzyme electrode, based on the oxygen electrode, and containing immobilized glucose oxidase and hexokinase is described for the measurement of 0.2–3 mM adenosine triphosphate.     

Self-assembly of S-layer-enveloped cytochrome c polyelectrolyte multilayers

We report a study of the electrostatic layer-by-layer self-assembly of electroactive polyelectrolyte multilayers incorporating the redox protein cytochrome c (cyt c) combined with recrystallization of the bacterial cell wall surface layer from Bacillus sphaericus CCM 2177 SbpA (S-layer). The polyelectrolyte multilayer assembly was prepared on flat gold electrodes with a nanometer-scale roughness that allowed monitoring of the film formation throughout all the assembly stages by atomic force microscopy measurements in liquid with respect to topography and forces. The deposition of alternating layers of sulfonated polyaniline and cyt c was carried out by adsorption from the corresponding solutions on a cyt c monolayer electrode. The electroactivity of cyt c within the assembly was confirmed by cyclic voltammetry. We showed that the surface properties of the electrode terminating layer change after each adsorption step accordingly. We also found that S-layer recrystallization on the top of the multilayer film was feasible while electroactivity of cyt c within a polyelectrolyte matrix was partially maintained. This approach offers a new strategy to design a biocompatible and permselective outer envelope of a polyelectrolyte multilayer, promising sensor applications.     

The effect of long-term exposure to combinations of growth promoters in Long Evans rats: part 1: Endocrine adrenal function

The aim of the study was to investigate whether the chronic administration (45 days) of clenbuterol (CB) at a growth promoting dose (1 mg kg(-1) bw) and/or dexamethasone (DEX: 0.1 mg kg(-1) bw) may cause the disruption of rat endocrine adrenal function. Blood samples were taken weekly during the whole experiment (S0-S7), and at different days of withdrawal (W0, W5, W10, W15 and W20). Hormone profiles were determined by RIA (ACTH) or EIA (corticosterone and catecholamines). ACTH showed significantly elevated concentrations from S1 until W5 (p<0.05) with CB administration. It began to decrease the day of DEX and CB-DEX administration. DEX showed significantly lowered ACTH concentrations from the day of drug injection (p<0.05). Corticosterone showed significantly elevated levels until W10 (p<0.01) with CB and CB+DEX. DEX showed lowered levels of corticosterone during the whole withdrawal period. Epinephrine presented significantly elevated plasma levels until W5 with CB and CB+DEX. With DEX, epinephrine was also elevated from W5 to W15 (p<0.05). Norepinephrine also presented significantly elevated plasma levels until S7 with CB and CB+DEX (p<0.001). With DEX no differences were found. Conclusion: Long-term administration of CB and/or DEX causes an endocrine adrenal disruption with changes in ACTH, glucocorticoid and catecholamine secretion.