Stability of fatty acyl-coenzyme a thioester ligands of hepatocyte nuclear factor-4α and peroxisome proliferator-activated receptor-α

Although long-chain fatty acyl-coenzyme A (LCFA-CoA) thioesters are specific high-affinity ligands for hepatocyte nuclear factor-4α (HNF-4α) and peroxisome proliferator-activated receptor-α (PPARα), X-ray crystals of the respective purified recombinant ligand-binding domains (LBD) do not contain LCFA-CoA, but instead exhibit bound LCFA or have lost all ligands during the purification process, respectively. As shown herein: (i) The acyl chain composition of LCFA bound to recombinant HNF-4α reflected that of the bacterial LCFA-CoA pool, rather than the bacterial LCFA pool. (ii) Bacteria used to produce the respective HNF-4α and PPARα contained nearly 100-fold less LCFA-CoA than LCFA. (iii) Under conditions used to crystallize LBD (at least 3 wk at room temperature in aqueous buffer), 16∶1-CoA was very unstable in buffer alone. (iv) In the presence of the respective nuclear receptor (i.e., HNF-4α and PPARα), LBD 70–75% of 16∶1-CoA was degraded after 1 d at room temperature in the crystallization buffer, whereas as much as 94–97% of 16∶1-CoA was degraded by 3 wk. (v) Cytoplasmic LCFA-CoA binding proteins such as acyl-CoA binding protein, sterol carrier protein-2, and liver-FA binding protein slowed the process of 16∶1-CoA degradation proportional to their respective affinities for this ligand. Taken together, these data for the first time indicated that the absence of LCFA-CoA in the crystallized HNF-4α and PPARα was due to the paucity of LCFA-CoA in bacteria as well as to the instability of LCFA-CoA in aqueous buffers and the conditions used for LBD crystallization. Furthermore, instead of protecting bound LCFA-CoA from autohydrolysis like several cytoplasmic LCFA-CoA binding proteins, these nuclear receptors facilitated LCFA-CoA degradation.     

Calculation of cosmic ray limited maximum DC blocking voltages of high voltage silicon PIN diodes

A power law approach as used by Fulop for the treatment of impact ionization and breakdown in abrupt silicon P–N junctions [Fulop W. Calculation of avalanche breakdown voltages of silicon P–N junctions. Solid-State Electron. 1967;10:39–43] is developed in this paper to provide simple-to-use equations for the quantitative evaluation of cosmic ray related phenomena in high voltage power devices. Being empirical in nature, such approaches have no physical background and only serve the purpose of generating a simple and compact mathematical framework. The resulting compact model allows for a quick and straightforward computation of DC blocking voltages as a function of FIT rate, n-base doping and temperature. The determination of model parameters is based on the theory and data given in [Zeller HR. Cosmic ray induced failures in high power semiconductor devices. Solid-State Electron. 1995;38(12):2041–6]. With the new approach, calculating first-hand maximum DC blocking voltages for high voltage power semiconductor devices becomes as effortless as the calculation of the breakdown voltage.     

Optimization of the Liquid Distributor in a Falling Film Evaporator by Means of Air‐Water Experiments

Air‐water experiments (cold‐flow experiments) were performed for the liquid distributor of an industrial falling film evaporator (FFE). The feed to the FFE is superheated and a flash evaporation occurs in the head of the FFE. The aim of the experiments was to investigate the vapor‐liquid flow in the head and the resulting liquid distribution to the evaporator tubes. Several different designs of the distributor were investigated and explanations for the performance losses of the real evaporator over time were found. Several measures were finally concluded and also implemented for the real FFE.     

Effects of catch crops on silage maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.): yield,nitrogen uptake efficiency and losses

Under the climatic conditions of north-western Europe, silage maize (Zea mays L.) production optimized with respect to nitrogen (N) fertilization and crop rotation is required to reduce N losses. Whether winter catch crops (CC) can serve as a beneficial biological tool in terms of N-loss abatement as well as maize yield also under optimized N management, is unclear. Therefore, a 2-year field experiment was conducted to study the short-term effects of a continuous maize-catch cropping system on maize yield performance, N₂O emission and N leaching, as affected by maize harvest/CC sowing date (10, 20, 30 September and 15 October, respectively, hd₁–hd₄) and CC species (rye, Secale cereale L. and Italian ryegrass, Lolium multiflorum Lam.). Treatments without CC served as control and N fertilization was applied as synthetic N to better adjust to maize N demand. The CC treatment (with or without) had no effect on maize dry matter and N yields, but the N uptake efficiency of maize responded significantly to the N accumulation (N_tot) of CC. Nitrate leaching mostly stayed below the critical load value for EU drinking water and rye significantly reduced nitrate leaching, given that environmental conditions allowed sufficiently high CC biomass accumulation. Annual nitrous oxide emission was unaffected by CC treatment. Restricted N fertilization of maize following CC led to N deficiency, since CC decomposition obviously was not synchronized with maize N demand. Under the given environmental conditions, rye may serve as beneficial CC in continuous maize cropping even in already optimized N management.     

Optisch aktive Amine durch Lipase-katalysierte Methoxyacetylierung

Optically Active Amines via Lipase-Catalyzed Methoxyacetylation Racemic amines can be efficiently resolved using ethylmethoxyacetate as acylating agent in a lipase-catalyzed reaction. The reaction of 1-phenyethylamine with ethylmethoxyacetate in the presence of a lipase from Burkholderia plantarii is presented. Excellent yields and selectivity and minimal amount of enzyme characterize this new process.     

Fluorescence Techniques Using Dehydroergosterol to Study Cholesterol Trafficking

Cholesterol itself has very few structural/chemical features suitable for real-time imaging in living cells. Thus, the advent of dehydroergosterol [ergosta-5,7,9(11),22-tetraen-3β-ol, DHE] the fluorescent sterol most structurally and functionally similar to cholesterol to date, has proven to be a major asset for real-time probing/elucidating the sterol environment and intracellular sterol trafficking in living organisms. DHE is a naturally occurring, fluorescent sterol analog that faithfully mimics many of the properties of cholesterol. Because these properties are very sensitive to sterol structure and degradation, such studies require the use of extremely pure (>98%) quantities of fluorescent sterol. DHE is readily bound by cholesterol-binding proteins, is incorporated into lipoproteins (from the diet of animals or by exchange in vitro), and for real-time imaging studies is easily incorporated into cultured cells where it co-distributes with endogenous sterol. Incorporation from an ethanolic stock solution to cell culture media is effective, but this process forms an aqueous dispersion of DHE crystals which can result in endocytic cellular uptake and distribution into lysosomes which is problematic in imaging DHE at the plasma membrane of living cells. In contrast, monomeric DHE can be incorporated from unilamellar vesicles by exchange/fusion with the plasma membrane or from DHE-methyl-β-cyclodextrin (DHE-MβCD) complexes by exchange with the plasma membrane. Both of the latter techniques can deliver large quantities of monomeric DHE with significant distribution into the plasma membrane. The properties and behavior of DHE in protein-binding, lipoproteins, model membranes, biological membranes, lipid rafts/caveolae, and real-time imaging in living cells indicate that this naturally occurring fluorescent sterol is a useful mimic for probing the properties of cholesterol in these systems.     

省时节能的iFlash(R)间歇式前处理/染色工艺

介绍了iFlash(R)间歇式前处理/染色系统的特点,如低温低碱漂白、高效皂洗等;就加工时间、处理效果及加工成本与常规前处理/染色工艺进行了比较.实践证明,iFlash(R)系统具有省时、省水、节能、环保、改善织物性能等特点.