FT-Raman-Spectroscopic Study on the Luminescence of Synthetic and Mineral Apatites

 Strong luminescence bands can be present in NIR-excited FT-Raman spectra of certain inorganic materials like hydroxyapatite. Since the origin of these emissions exclusively occurring on NIR-excitation is still unclear, a variety of synthetic and mineral apatites and related calcium salts was studied by means of Stokes and anti-Stokes FT-Raman spectroscopy, X-ray diffraction, and geochemical analyses. The results indicate that the occurrence of the luminescence is in some way related to foreign ion contents. However, a direct correlation to a specific ion could not be found on the basis of available data.     

SET‐LRP of methyl methacrylate initiated with sulfonyl halides

Single electron transfer‐living radical polymerization (SET‐LRP) represents a robust and versatile method for the rapid synthesis of macromolecules with defined architecture. The present article describes the polymerization of methyl methacrylate by SET‐LRP in protic solvent mixtures. Herein, the polymerization process was catalyzed by a straightforward Cu(0)wire/Me₆‐TREN catalyst while initiation was obtained by toluenesulfonyl chloride. All experiments were conducted at 50 °C and the living polymerization was demonstrated by kinetic evaluation of the SET‐LRP. The process follows first order kinetic until all monomer is consumed which was typically achieved within 4 h. The molecular weight increased linearly with conversion and the molecular weight distributions were very narrow with M_w/M_n ～ 1.1. Detailed investigations of the polymer samples by MALDI‐TOF confirmed that no termination took place and that the chain end functionality is retained throughout the polymerization process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2236–2242, 2010     

Vasodilatation Function of Cerebral Vessels at Arterial Hypertension in OXYS Rats

OXYS rats represent a selection strain of laboratory animals, which are characterized by the accelerated senescence. Substantial morphologic changes of cerebral vessels were revealed in the senescence-accelerated OXYS rats by the noninvasive MRI diagnostics using the induced arterial hypertension and the author’s original methods. These changes appeared as vascular lesions with a thickening of the intimae and the increasing of the signal intensity from blood in cerebral vessels. Cerebral arterial hypertension in normotensive Wistar rats developed as result of intraperitoneal injections of hydrocortisone acetate and diet enriched by sodium ions. The pathology of cerebral vessels in OXYS rats began its development much earlier and was based on spontaneous hypertension in connection with initially elevated blood pressure as well as the genotype of the animals. Four different inductors (two vasodilators and two vasoconstrictors) were used in the study of the endothelium-independent and endothelium-dependent vasodilatation and vasoconstrictions. We have compared previously unknown effects of these inductors on cerebral vessels in senescence-accelerated OXYS rats and those in normal Wistar rats. The response of the arteries to the action of inductors showed changes in the status of anterior, middle, and posterior cerebral arteries of circle Willis. Thus, we have indicated the changes in compensatory and adaptive characters of arteries in hypertensive OXYS rats in comparison with hypertensive Wistar rats. Reduced vasodilator response in the middle cerebral arteries suggests an elevated risk for development of arterial hypertension in these rats.     

Enzymatic Degradation of (Ligno)cellulose

Glycoside‐degrading enzymes play a dominant role in the biochemical conversion of cellulosic biomass into low‐price biofuels and high‐value‐added chemicals. New insight into protein functions and substrate structures, the kinetics of recognition, and degradation events has resulted in a substantial improvement of our understanding of cellulose degradation.     

Intramolecular stable carbon isotopic analysis of archaeal glycosyl tetraether lipids

Glycolipids are prominent constituents in the membranes of cells from all domains of life. For example, diglycosyl‐glycerol dibiphytanyl glycerol tetraethers (2Gly‐GDGTs) are associated with methanotrophic ANME‐1 archaea and heterotrophic benthic archaea, two archaeal groups of global biogeochemical importance. The hydrophobic biphytane moieties of 2Gly‐GDGTs from these two uncultivated archaeal groups exhibit distinct carbon isotopic compositions. To explore whether the isotopic compositions of the sugar headgroups provide additional information on the metabolism of their producers, we developed a procedure to analyze the δ¹³C values of glycosidic headgroups. Successful determination was achieved by (1) monitoring the contamination from free sugars during lipid extraction and preparation, (2) optimizing the hydrolytic conditions for glycolipids, and (3) derivatizing the resulting sugars into aldononitrile acetate derivatives, which are stable enough to withstand a subsequent column purification step. First results of δ¹³C values of sugars cleaved from 2Gly‐GDGTs in two marine sediment samples, one containing predominantly ANME‐1 archaea and the other benthic archaea, were obtained and compared with the δ¹³C values of the corresponding biphytanes. In both samples the dominant sugar headgroups were enriched in ¹³C relative to the corresponding major biphytane. This ¹³C enrichment was significantly larger in the putative major glycolipids from ANME‐1 archaea (～15‰) than in those from benthic archaea (<7‰). This method opens a new analytical window for the examination of carbon isotopic relationships between sugars and lipids in uncultivated organisms. Copyright © 2010 John Wiley & Sons, Ltd.