1H-NMR-spektroskopische Analyse von 2-Dimethylamino-[1,3,2]dioxarsolan und -dithiarsolan

¹H-n.m.r. Spectroscopic Analysis of 2-Dimethylamino-[1,3,2] dioxarsolane and Dithiarsolane The ¹H-n.m.r. spectra of (CH₂)₂X₂As N(CH₃)₂ (X = O, S) show an AA′BB′ spin system for the protons of the methylene group which is reduced to an A₄ system by addition of HN(CH₃)₂. This reduction proves a rapid exchange of the N(CH₃)₂ group. This assumption is proved by isotope marking with ¹⁵N-marked dimethylamine.     

Determination of the Be half-life by multicollector ICP-MS and liquid scintillation counting

A new method was designed and used for determining the half-life of the isotope ¹⁰Be. The method is based on (1) accurate ¹⁰Be/⁹Be measurements of ⁹Be-spiked solutions of a ¹⁰Be-rich master solution using multicollector ICP mass spectrometry (MC-ICP-MS) and (2) liquid scintillation counting (LSC) using the CIEMAT/NIST method for determining the activity concentrations of the solutions whose ¹⁰Be concentrations were determined by mass spectrometry. Important requirements for the success of this approach (a) was the previous coating of glass ampoules filled for counting experiments with ⁹Be, thereby reducing the risk of the adsorptive loss of ¹⁰Be; (b) the removal of Boron from solutions to be measured by MC-ICP-MS by cation chromatography without the introduction of mass fractionation and (c) the accurate determination of the mass bias of ¹⁰Be/⁹Be measurements by ICP-MS which are always affected by the space-charge effect. The mass bias factor was determined to be 1.1862 ± 0.071 for ¹⁰Be/⁹Be from careful fitting and error propagation of ratios of measured Li, B, Si, Cr, Fe, Cu, Sr, Nd, Hf, Tl and U standard solutions of known composition under the same measurement conditions. Employing this factor, an absolute ¹⁰Be/⁹Be ratio of 1.464 ± 0.014 was determined for a first dilution of the ¹⁰Be-rich master solution. This solution is now available as an absolute Be ratio standard in AMS measurements. Finally, a half-life of (1.386 ± 0.016) My (standard uncertainty) was calculated. This value is much more precise than previous estimates and was derived from a fully independent set of experiments. In a parallel, fully independent study using the same master solution, Korschinek et al. [35] have determined a half-life of (1.388 ± 0.018) My. The combined half-life and uncertainty amounts to (1.387 ± 0.012) My. We suggest the use of this value in nuclear studies and in studies that make use of cosmogenic ¹⁰Be in environmental and geologic samples.     

Evaluation of modified adaptive k-means segmentation algorithm

Computational Visual Media - Segmentation is the act of partitioning an image into different regions by creating boundaries between regions. k-means image segmentation is the simplest prevalent...     

Studies of edible Amazonian plants. Part 5: Chemical characterisation of Amazonian Endopleura uchi fruits

The chemical composition of the fruit pulp of Endopleura uchi growing in the Brazilian Amazon was investigated for characterisation and evaluation of its nutritional value. According to the analyses performed, it possesses a considerably high content of fat, characterised by a high oleic acid content. The fruit also contains remarkably high amounts of dietary fibres and phytosterols, as well as notable contents of vitamin C, vitamin E and minerals. In total, 42 volatile compounds could be identified by GC-MS in the fruit pulp aroma, which consisted mainly of the alcoholic compounds 3,3-dimethyl-2-butanol (18.8%) and eugenol (14.0%), as well as methyl and ethyl esters of fatty acids (18.5%).     

Acyl-CoA binding proteins: Multiplicity and function

The physiological role of long-chain fatty acyl-CoA is thought to be primarily in intermediary metabolism of fatty acids. However, recent data show that nM to μM levels of these lipophilic molecules are potent regulators of cell functionsin vitro. Although long-chain fatty acyl-CoA are present at several hundred μM concentration in the cell, very little long-chain fatty acyl-CoA actually exists as free or unbound molecules, but rather is bound with high affinity to membrane lipids and/or proteins. Recently, there is growing awareness that cytosol contains nonenzymatic proteins also capable of binding long-chain fatty acyl-CoA with high affinity. Although the identity of the cytosolic long-chain fatty acyl-CoA binding protein(s) has been the subject of some controversy, there is growing evidence that several diverse nonenzymatic cytosolic proteins will bind long-chain fatty acyl-CoA. Not only does acyl-CoA binding protein specifically bind medium and long-chain fatty acyl-CoA (LCFA-CoA), but ubiquitous proteins with multiple ligand specificities such as the fatty acid binding proteins and sterol carrier protein-2 also bind LCFA-CoA with high affinity. The potential of these acyl-CoA binding proteins to influence the level of free LCFA-CoA and thereby the amount of LCFA-CoA bound to regulatory sites in proteins and enzymes is only now being examined in detail. The purpose of this article is to explore the identity, nature, function, and pathobiology of these fascinating newly discovered long-chain fatty acyl-CoA binding proteins. The relative contributions of these three different protein families to LCFA-CoA utilization and/or regulation of cellular activities are the focus of new directions in this field.     

Congestion, Dilation, and Energy in Radio Networks

We investigate the problem of path selection in radio networks for a given static set of n sites in two- and three-dimensional space. For static point-to-point communication we define measures for congestion, dilation, and energy consumption that take interferences among communication links into account. We show that energy-optimal path selection for radio networks can be computed in polynomial time. Then we introduce the diversity g(V) of a set V ⫅ ℝ^d for any constant d. It can be used to upper bound the number of interfering edges. For real-world applications it can be regarded as Θ(log n). A main result is that a c-spanner construction as a communication network allows one to approximate the congestion-optimal path system by a factor of O(g(V)²). Furthermore, we show that there are vertex sets where only one of the performance parameters congestion, dilation, and energy can be optimized at a time. We show trade-offs lower bounding congestion × dilation and dilation × energy. The trade-off between congestion and dilation increases with switching from two-dimensional to three-dimensional space. For congestion and energy the situation is even worse. It is only possible to find a reasonable approximation for either congestion or energy minimization, while the other parameter is at least a polynomial factor worse than in the optimal network.     

Liver Fatty Acid Binding Protein Gene-Ablation Exacerbates Weight Gain in High-Fat Fed Female Mice

Loss of liver fatty acid binding protein (L‐FABP) decreases long chain fatty acid uptake and oxidation in primary hepatocytes and in vivo. On this basis, L‐FABP gene ablation would potentiate high‐fat diet‐induced weight gain and weight gain/energy intake. While this was indeed the case when L‐FABP null (?/?) mice on the C57BL/6NCr background were pair‐fed a high‐fat diet, whether this would also be observed under high‐fat diet fed ad libitum was not known. Therefore, this possibility was examined in female L‐FABP (?/?) mice on the same background. L‐FABP (?/?) mice consumed equal amounts of defined high‐fat or isocaloric control diets fed ad libitum. However, on the ad libitum‐fed high‐fat diet the L‐FABP (?/?) mice exhibited: (1) decreased hepatic long chain fatty acid (LCFA) β‐oxidation as indicated by lower serum β‐hydroxybutyrate level; (2) decreased hepatic protein levels of key enzymes mitochondrial (rate limiting carnitine palmitoyl acyltransferase A1, CPT1A; HMG‐CoA synthase) and peroxisomal (acyl CoA oxidase 1, ACOX1) LCFA β‐oxidation; (3) increased fat tissue mass (FTM) and FTM/energy intake to the greatest extent; and (4) exacerbated body weight gain, weight gain/energy intake, liver weight, and liver weight/body weight to the greatest extent. Taken together, these findings showed that L‐FABP gene‐ablation exacerbated diet‐induced weight gain and fat tissue mass gain in mice fed high‐fat diet ad libitum—consistent with the known biochemistry and cell biology of L‐FABP.