Untersuchung von Luft und Dampf

Ohne Zusammenfassung     

Dual functional polyelectrolyte multilayer coatings for implants: permanent microbicidal base with controlled release of therapeutic agents

Here we present a new bifunctional layer-by-layer (LbL) construct made by combining a permanent microbicidal polyelectrolyte multilayered (PEM) base film with a hydrolytically degradable PEM top film that offers controlled and localized delivery of therapeutics. Two degradable film architectures are presented: (1) bolus release of an antibiotic (gentamicin) to eradicate initial infection at the implant site, or (2) sustained delivery of an anti-inflammatory drug (diclofenac) to cope with inflammation at the site of implantation due to tissue injury. Each degradable film was built on top of a permanent base film that imparts the implantable device surface with microbicidal functionality that prevents the formation of biofilms. Controlled-delivery of gentamicin was demonstrated over hours and that of diclofenac over days. Both drugs retained their efficacy upon release. The permanent microbicidal base film was biocompatible with A549 epithelial cancer cells and MC3T3-E1 osteoprogenitor cells, while also preventing bacteria attachment from turbid media for the entire duration of the two weeks studied. The microbicidal base film retains its functionality after the biodegradable films have completely degraded. The versatility of these PEM films and their ability to prevent biofilm formation make them attractive as coatings for implantable devices.     

Empirical correction of crosstalk in a low-background germanium γ–γ analysis system

The Pacific Northwest National Laboratory (PNNL) is currently developing a custom software suite capable of automating many of the tasks required to accurately analyze coincident signals within gamma spectrometer arrays. During the course of this work, significant crosstalk was identified in the energy determination for spectra collected with a new low-background intrinsic germanium (HPGe) array at PNNL. The HPGe array is designed for high detection efficiency, ultra-low-background performance, and sensitive γ–γ coincidence detection. The first half of the array, a single cryostat containing seven HPGe crystals, was recently installed into a new shallow underground laboratory facility. This update will present a brief review of the germanium array, describe the observed crosstalk, and present a straight-forward empirical correction that significantly reduces the impact of this crosstalk on the spectroscopic performance of the system.     

A RAPID APPROXIMATION FOR PREDICTING THE HYDROCARBON DISCOVERY RATE: PART 2. IMPROVING THE ACCURACY

In Part 1 of this paper, we noted the systematic errors in the estimates of means and standard deviations produced by a rapid approximation applied to a model of hydrocarbon discovery. In Part 2, we apply regression to predict the approximation errors, as functions of model parameters and approximation output. With the regression model, we can correct much of the error in the approximation, as we illustrate with data from the Nisku-Shelf play of western Canada.     

Temperature-dependent crystal structure of the isopropanol clathrate of Dianin's compound

The title compound undergoes two order-disorder transitions between 15 and 299 K, dictated by ordering of the guest molecules in the host cages, and resulting in three related crystal structures. We anticipate behaviour of this kind to be widespread, and speculate that the concept of "the crystal structure" for individual Dianin's clathrates may be elusive.     

基于氨基酸的古代食谱重建

古代食谱重建是目前国际考古学研究的热点之一。随着研究的深入,传统基于骨骼提取出骨胶原蛋白进行分析的方法逐渐凸显出一定的局限性。尤其是在考察先民食物结构和营养等级等方面,针对蛋白大分子获得的同位素信息,无法排除一些内在或外在因素的影响,因而常会引导我们做出错误的判断。因此,发展一种能进一步提高古代食谱研究准确率和分辨率的新方法,是当前科技考古研究的迫切需求。不同于大分子蛋白,氨基酸能在更细微的层面提供有机体和生态环境中有机代谢过程中多方面的信息,在生物考古领域内具有极大的应用潜力。以北非突尼斯迦太基凡达里奇墓地出土的人和动物样品为例（遗址年代约在公元5世纪中期至6世纪早期）,进行基于骨胶原和单分子氨基酸的稳定同位素分析工作。对10个人和4具动物考古样品提取骨胶原,并进一步进行酸水解、衍生化等操作,通过气相色谱（GC）与同位素质谱（IRMS）串联技术,开展特定化合物同位素分析。研究结果揭示了该遗址先民的食谱特征,以C₃类食物为主。重点考察了该遗址先民饮食中的蛋白摄入情况,结果表明该遗址先民饮食摄入有大量的动物蛋白,且不同个体存在较大差异。最后,通过对骨胶原和氨基酸分析结果所得结论的比较,证实基于单分子氨基酸的氮同位素分析对个体营养级位置的准确判断具有较大的优势。研究结果为深入研究我国古代先民食物结构差异和人群分化等问题提供了新的思路和依据。研究证实基于单分子氨基酸的同位素分析,将是显著提高古代食谱重建分辨率的有力手段,呼吁未来在我国考古材料中开展大量相关研究。     

Structure and magnetism of Coa(1−x)MnaxGeb epitaxial films

The structural and magnetic phase diagrams of Co_a(1−x)Mn_axGe_b epitaxial films near the composition of Heusler alloy Co₂MnGe have been studied using combinatorial molecular beam epitaxy techniques. Epitaxial growth on Ge (1 1 1) has been stabilized over nearly the entire composition range of the ternary system. Epitaxial constraints play an important role for the small number of observed structural phases. The variety of high-temperature magnetic properties, and the structural and chemical compatibilities with group IV elements make the ternary system promising for the science and applications of spintronics.