Dark Fermentative Hydrogen Production from Neutralized Acid Hydrolysates of Conifer Pulp

Concentrated acid hydrolysis of cellulosic material results in high dissolution yields. In this study, the neutralization step of concentrated acid hydrolysate of conifer pulp was optimized. Dry conifer pulp hydrolysis with 55?% H₂SO₄ at 45?°C for 2?h resulted in total sugar yields of 22.3?C26.2?g/L. The neutralization step was optimized for solid Ca(OH)₂, liquid Ca(OH)₂ or solid CaO, mixing time, and water supplementation. The highest hydrogen yield of 1.75?mol?H₂/mol glucose was obtained with liquid Ca(OH)₂, while the use of solid Ca(OH)₂ or CaO inhibited hydrogen fermentation. Liquid Ca(OH)₂ removed sulfate to below 30?mg SO₄ ^2?/L. Further optimization of the neutralization conditions resulted in the yield of 2.26?mol?H₂/mol glucose.     

Oberfl?cheneigenschaften und Mizellenbildung von nichtionogenen oberfl?chenaktiven Polyoxy?thylenen mit langen Ketten

Ohne Zusammenfassung     

Improved methods for thermal rearrangement of alicyclic α-hydroxyimines to α-aminoketones: synthesis of ketamine analogues as antisepsis candidates

Ketamine is an analgesic/anesthetic drug, which, in combination with other drugs, has been used as anesthetic for over 40 years. Ketamine induces its analgesic activities by blocking the N-methyl-D-aspartate (NMDA) receptor in the central nervous system (CNS). We have reported that low doses of ketamine administrated to patients before incision significantly reduced post-operative inflammation as reflected by reduced interleukin-6 (IL-6) sera-levels. Our data demonstrated in a rat model of Gram-negative bacterial-sepsis that if we inject a low dose of ketamine following bacterial inoculation we reduce mortality from approximately 75% to 25%. Similar to what we have observed in operated patients, the levels of TNF-α and IL-6 in ketamine-treated rats were significantly lower than in septic animals not treated with ketamine. On the base of these results, we have designed and synthesized series of new analogues of ketamine applying a thermal rearrangement of alicyclic α-hydroxyimines to a-aminoketones in parallel arrays. One of the analogues (compound 6e) displayed high activity in down-regulating the levels of IL-6 and TNF-α in vivo as compared to ketamine.     

A rapid method for the determination of radiostrontium in river water

A rapid analytical method, applicable for the selective separation and determination of⁹⁰Sr and⁸⁹Sr in river water, is described. Strontium is extracted from the water sample at pH 10.5 by TTA/TOPO in cyclohexane in the presence of Tiron as masking agent for interfering ß-emitters. Radiostrontium is measured by liquid scintillation after back-extraction into 1N nitric acid. The distribution coefficient of strontium is over 400 and the separation factors from other radionuclides are higher than 5.0×10³.     

Oberflächeneigenschaften und Mizellenbildung von nichtionogenen oberflächenaktiven Polyoxyäthylenen mit langen Ketten

Ohne Zusammenfassung     

Fluorophor-enhanced cathodic electroluminescence at an oxide-covered aluminum electrode

Symmetric double-step potential (i.e., positive and negative potential) pulses with intermittent zero potential pulses at the oxide-covered aluminum electrode generates anodic and cathodic electroluminescence in an aqueous environment in the presence of potassium peroxodisulfate. Organic fluorescent compounds generate changes in the cathodic electroluminescence but not in the anodic emission: intensity is greatly enhanced and the spectrum of a fluorophor-enhanced electroluminescence becomes similar to the fluorescence spectrum of the fluorophor. The mechanism of the fluorophor-enhanced peroxodisulfate-induced cathodic electroluminescence is discussed. It is demonstrated by means of salicylic acid as the model fluorophor that this electroluminescence can be exploited to determine trace organic fluorescent compounds.     

Theoretical investigations on Ziegler-Natta catalysis: Alkylation of the TiCl4 catalyst

Theoretical ab initio methods have been used to study the alkylation reaction of the MgCl₂-supported TiCl₄ catalyst. Investigation of the reaction path indicated that the Al(CH₃)₃ co-catalyst inserts into the coordination sphere of the titanium atom of the catalyst so that a methyl group of Al(CH₃)₃ interacts with the titanium. The methyl group migrates from Al(CH₃)₃ to the vacant coordination site of the catalyst. When the catalyst loses one of its chlorine atoms to the co-catalyst during this reaction, the catalyst maintains its vacant site, but the position of the vacant site changes. The presence of the external electron donor coordinated to the co-catalyst makes the alkylation reaction energetically more favourable.     

Synthetic studies in the alkaloid field—X: Preparation and stereostructure determination of several indolo [2,3-a]quinolizine derivatives

The C(12b)-C(1)-C(2)-C(3) stereochemical relationship in several racemic indolo[2,3-a]quinolizine derivatives has been determined by the application of conformational considerations to the ¹³C NMR spectral analysis. The proper shift assignment was confirmed by recording the spectra of selectively deuterated derivatives. The C(12b)-C(1)-C(2)-C(3) stereochemical relationship in indolo[2,3-a]quinolizines obtained by acid-induced cyclizadon of partially hydrogenated 3,5-dimethoxycarbonyl-1-[2-(3-indolyl)ethyl]pyridine derivatives is discussed.     

Low-spin states in151Gd

The level structure of the 87-neutron nucleus¹⁵¹Gd has been investigated by studying the EC- andβ ⁺-decay of¹⁵¹Tb. Gamma-ray and conversion electron spectra as well as gamma-gamma coincidence spectra were measured by using semiconductor spectrometers and a high-capacity two-parameter recording system. The proposed decay scheme contains several new energy levels in¹⁵¹Gd, among them a 5^?/2 state at 427 keV. To explain the low-energy level structure, a small stable deformation is assumed for¹⁵¹Gd. Using a single-particle-plus-rotor model based on a generalized Woods-Saxon potential, complete mixing of the shells 1h _9/2, 2f _7/2 and separately 1i _13/2 is observed. By these mixings the correct level order and approximately correct excitation energies up to 1 MeV are reproduced.