TET-Like Oxidation in 5-Methylcytosine and Derivatives: A Computational and Experimental Study

The epigenetic marker 5-methylcytosine (5mC) is an important factor in DNA modification and epigenetics. It can be modified through a three-step oxidation performed by ten-eleven-translocation (TET) enzymes and we have previously reported that the iron(IV)-oxo complex [Fe(O)(Py₅Me₂H)]²⁺ ( 1 ) can oxidize 5mC. Here, we report the reactivity of this iron(IV)-oxo complex towards a wider scope of methylated cytosine and uracil derivatives relevant for synthetic DNA applications, such as 1-methylcytosine (1mC), 5-methyl-iso-cytosine (5miC) and thymine (T/5mU). The observed kinetic parameters are corroborated by calculation of the C−H bond energies at the reactive sites which was found to be an efficient tool for reaction rate prediction of 1 towards methylated DNA bases. We identified oxidation products of methylated cytosine derivatives using HPLC-MS and GC-MS. Thereby, we shed light on the impact of the methyl group position and resulting C−H bond dissociation energies on reactivity towards TET-like oxidation.     

The Kinetics of Phase Separation in Liquid-Liquid Extraction: Modeling of Droplet Swarm Coalescence

The kinetics of droplet-bulk coalescence in liquid-liquid phase separation was investigated. A modified 1st order rate model was applied to fit the data of three series of experiments with different physical properties. This rate model can characterize the coalescence curve with two kinetic parameters, which are basically just fit parameters. The fit parameters were compared with the physical properties of the investigated systems. They compare well with the density, viscosity, and interfacial tension. The outcome of this study offers a simple and easy to apply tool for kinetic modeling of the coalescence process.     

A nanoscale standard for the Seebeck coefficient

The Seebeck coefficient, a key parameter describing a material's thermoelectric performance, is generally difficult to measure, and no intrinsic calibration standard exists. Quantum dots and single electron tunneling devices with sharp transmission resonances spaced by many kT have a material-independent Seebeck coefficient that depends only on the electronic charge and the average device temperature T. Here we propose the use of a quantum dot to create an intrinsic, nanoscale standard for the Seebeck coefficient and discuss its implementation.     

Improving long term oxidation protection for γ‐TiAl substrates

In previous work, a thermal spray multilayer system consisting of Zirconia (ZrO₂) and MCrAlY top coat showed promising results regarding the oxidation behavior of the Gamma Titanium Aluminides substrates tested, which encouraged further research activities. Diffusion of substrate material was successfully inhibited by a ceramic Zirconia coating. A building up of a dense and stable oxide layer could be achieved by additional application of an MCrAlY top coat, leading to improved oxidation resistance and thus showing feasibility. In this work the main focus for development was put on enhancing adhesion and lowering residual stresses of the coatings in order to allow long term and cyclic testing without delamination taking place. Being a very brittle material, Gamma Titanium Aluminides require special surface treatment to enable roughening which is crucial for a strong mechanical bond between substrate and coating. Alternatives to conventional grit blasting as a standard preparation method were investigated. These were micro‐abrasive blasting and blasting at elevated temperature (≈300–550°C) to allow a more ductile behavior. The paper will highlight the implications by means of these measures and will also show the present development status of the multilayer system.     

西安某综合楼水模块空调系统的优化改造设计

对某综合楼中使用的"水模块+风管机空调系统"的组成、工艺流程的改造等进行了论述,并同"散热器+分体空调系统"进行了经济对比。     

废水处理中的纺织品

1　引言纺织品生产需要好几道工序 ,这些工序需要大量淡水 (每吨纺织品需要 6 0ｍ3～ 2 0 0ｍ3的水量 )和许多不同的化学药品及助剂 ,如油剂、浆料、染料和涂料。这些物质最终只有约 40 %固定在纺织品上 ,其余未被使用的部分便以固体废物、废液以及废气的形式排出工厂。特别作为有机污染总和的参数ＣＯＤ值、颜色及废水中可吸附有机卤化物 (ＡＯＸ)的含量对环境具有很大的影响。棉织物生产加工过程中ＣＯＤ污染的大部分来自浆料 ,以一家德国纺织染整厂为例显示 :ＣＯＤ值的 40 .5 %来自浆料 ,2 7.0 %来自纺织助剂 ,1 5 .6 %来自化学药品 ,1 …     

塔里木盆地东北地区特殊地震相及其地质意义

特殊地震相是特定地质条件下的产物,一般发育在特定的区域构造位置和沉积体系中,具有反映沉积环境和指示沉积相的作用。塔里木盆地东北地区目前已初步查明有9种主要的特殊地震相类型,本文讨论了它们的地质影响因素、地震特征及油气勘探效果、它们的分布规律。可见,研究特殊地震相对寻找隐蔽圈闭油气藏有着重要的意义。     

Influence of Hyperglycemia and Diabetes on Cardioprotection by Humoral Factors Released after Remote Ischemic Preconditioning (RIPC)

Remote ischemic preconditioning (RIPC) protects hearts from ischemia–reperfusion (I/R) injury in experimental studies; however, clinical RIPC trials were unsatisfactory. This discrepancy could be caused by a loss of cardioprotection due to comorbidities in patients, including diabetes mellitus (DM) and hyperglycemia (HG). RIPC is discussed to confer protective properties by release of different humoral factors activating cardioprotective signaling cascades. Therefore, we investigated whether DM type 1 and/or HG (1) inhibit the release of humoral factors after RIPC and/or (2) block the cardioprotective effect directly at the myocardium. Experiments were performed on male Wistar rats. Animals in part 1 of the study were either healthy normoglycemic (NG), type 1 diabetic (DM1), or hyperglycemic (HG). RIPC was implemented by four cycles of 5 min bilateral hind-limb ischemia/reperfusion. Control (Con) animals were not treated. Blood plasma taken in vivo was further investigated in isolated rat hearts in vitro. Plasma from diseased animals (DM1 or HG) was administered onto healthy (NG) hearts for 10 min before 33 min of global ischemia and 60 min of reperfusion. Part 2 of the study was performed vice versa—plasma taken in vivo, with or without RIPC, from healthy rats was transferred to DM1 and HG hearts in vitro. Infarct size was determined by TTC staining. Part 1: RIPC plasma from NG (NG Con: 49 ± 8% vs. NG RIPC 29 ± 6%; p < 0.05) and DM1 animals (DM1 Con: 47 ± 7% vs. DM1 RIPC: 38 ± 7%; p < 0.05) reduced infarct size. Interestingly, transfer of HG plasma showed comparable infarct sizes independent of prior treatment (HG Con: 34 ± 9% vs. HG RIPC 35 ± 9%; ns). Part 2: No infarct size reduction was detectable when transferring RIPC plasma from healthy rats to DM1 (DM1 Con: 54 ± 13% vs. DM1 RIPC 53 ± 10%; ns) or HG hearts (HG Con: 60 ± 16% vs. HG RIPC 53 ± 14%; ns). These results suggest that: (1) RIPC under NG and DM1 induces the release of humoral factors with cardioprotective impact, (2) HG plasma might own cardioprotective properties, and (3) RIPC does not confer cardioprotection in DM1 and HG myocardium.     

Urban versus remote air concentrations of fluorotelomer alcohols and other polyfluorinated alkyl substances in Germany

Neutral, volatile polyfluorinated alkyl substances (PFAS) were measured in environmental air samples at two different sites in Northern Germany in spring 2005. The sampling locations were chosen to cover a metropolitan and a rural site, the Hamburg city center, and Waldhof, a background monitoring site. An optimized and validated analytical protocol was used to analyze two sets of parallel high-volume air samples. For both sampling locations as well as for individual samples, field blanks were taken to monitor possible background contamination. Gas chromatography coupled to mass spectrometry using positive chemical ionization (GC/ PCI-MS) was used for quantitative analyses. This article describes the first air concentration data of volatile PFAS outside North America reported in the peer-reviewed literature. The wide distribution of fluorotelomer alcohols (FTOHs), fluorinated sulfonamides, and sulfonamidoethanols (FOSAs/FOSEs) in German environmental air is presented. Furthermore, two volatile PFAS, i.e., N-methyl fluorooctane sulfonamide (NMeFOSA) and 4:2 FTOH, were determined for the first time in environmental air. Minimum-maximum sigmaFTOH concentrations of 64-311 pg/m3 (remote) up to 150-546 pg/m3 (urban) and minimum-maximum sigmaFOSA + FOSE concentrations between 12 and 54 pg/m3 (remote) and 29 and 151 pg/m3 (urban) were determined. 8:2 FTOH and 6:2 FTOH were found to be the predominant POPs determined in Waldhof so far. Blank contamination was found to be negligible. A significant correlation was found with the ambient temperature for the partitioning of airborne FOSEs between the gaseous and particulate phase (R = 0.853), whereas FTOHs and FOSAs were almost exclusively found in the gaseous phase. Furthermore, highest airborne PFAS concentrations were determined at relatively high ambient temperatures. Correlation coefficients (R) for sigmaFTOH and sigmaFOSA + FOSE concentrations with temperature were 0.954 and 0.968, respectively. Finally, the PFAS concentrations determined in this study are set into context with levels of "classical" persistent organic pollutants (POPs) in the same region and PFAS data available for North America.