Determinationof oxidation induction time and temperature bY DSC: Results of round robin tests

Results obtained from three round robin tests, performed in 1998, 2000 and 2004, are summarized and presented. Oxidation Induction Time (OITtime) and Oxidation Induction Temperature (OITtemp) on six different grades of polyethylene were measured by DSC. The measured data were collected by Empa and evaluated using a robust statistical method concerning repeatability and reproducibility standard deviation. The results of the tests indicate that the determination of OITtime is associated with a high degree of uncertainty, especially for low OITtime values. Thus, OITtemp measurements could be a valuable alternative for testing less stabilized or non-stabilized polyolefin in particular. However, OITtemp data reveal that the ability to distinguish between different polymer samples decreases drastically as OITtemp values increas

Transition-metal silicides formed by ion mixing and by thermal annealing: Which species moves?

The moving species during the formation of Pt2Si, Ni2Si, and CrSi2 by both ion mixing with 300–600 keV Xe ions and thermal annealing is identified with inert markers using backscattering spectrometry. Samples of metal-on-silicon and silicon-on-metal have been used, evaporated on SiO2 substrates with two very thin markers (Mo for Pt2Si, W for Ni2Si and CrSi2) placed at the metal–silicon interface, and at the bottom interface with the SiO2 substrate. Monitoring the separation of the two markers as a function of the amount of silicide formed determines the ratio of atomic transport through the growing silicide layer. The results establish that the dominant moving species in both silicide formation processes is the same for the refractory metal-silicide CrSi2, e.g., Si, whereas different atomic transport ratios are found in the case of the near-noble metal silicides Pt2Si and Ni2Si. This outcome is discussed in terms of high-temperature effects during thermal formation of transition-metal silicides

Adaptives Grundwassermanagement in urbanen Gebieten: Einfluss der Oberflächengewässer-Grundwasser-Interaktion am Beispiel künstlicher Grundwasseranreicherung sowie variabler In-/Exfiltration der Birs (Schweiz)

Zusammenfassung: Der Nutzungsdruck auf Grundwasserressourcen in intensiv genutzten Flussebenen wird zunehmend größer. Ziel dieses Beitrages ist, anhand eines repräsentativen, instationären Datensatzes eines urbanen Grundwassersystems (Unteres Birstal CH) aufzuzeigen, wie mit Ansätzen des adaptiven Grundwassermanagements die Voraussetzungen für die nachhaltige Nutzung von Grundwasserressourcen geschaffen werden können. Mithilfe eines instationären Grundwassermodells können spezifische Fragen der Fluss-Grundwasser-Interaktion und dem Betrieb künstlicher Grundwasseranreicherung beantwortet werden. Die Instationarität der Fluss-Grundwasser-Interaktion und eine damit zusammenhängende Änderung von In - und Exfiltrationsverhältnissen konnte für verschiedene Flussabschnitte ermittelt werden. Die Datenauswertung eines Jahrhunderthochwassers trug wesentlich zum Verständnis dieser Prozesse bei. Durch ein Experiment mit der längerfristigen Außerbetriebnahme einer künstlichen Grundwasseranreicherung im Untersuchungsgebiet konnten die Auswirkungen von geplanten Nutzungsänderungen abgeschätzt werden. Die Untersuchungen tragen zum Prozessverständnis des Grundwassersystems bei und liefern die Grundlage für eine Diskussion über lang-, mittel- und kurzfristige Ziele hinsichtlich der regionalen Bewirtschaftung urbaner Wasserressource

Sputtered W–N diffusion barriers

The thermal stability of reactively sputtered tungsten–nitrogen alloy thin films is investigated for the application as diffusion barriers in silicon contact metallizations. The composition of W–N barriers is varied over a wide range including pure W. Aluminum, gold, and silver are used as low resistivity overlayers. Metallurgical interactions at temperatures ranging from 500 to 900 °C are studied. Incorporating nitrogen into tungsten advantageously stabilizes all three systems. The overall failure takes place rapidly above critical temperatures that depend on both the metal overlayer and the microstructure of the barrier. In some cases, W–N alloys can effectively prevent interdiffusion at temperatures as high as 800 °C for 30 min

Moisture and Seasonality Shifts Recorded in Holocene and Pleistocene Speleothems From Southeastern Arabia

The source and seasonality of rainfall in southern Arabia during the early- to mid-Holocene and preceding humid periods are controversial because fossil lacustrine sediments provide solely indirect information on the amount of rainfall. Hydrogen and oxygen isotope measurements on fluid inclusion water trapped in Holocene and Pleistocene stalagmites from Hoti Cave in Northern Oman are direct indicators of the isotopic composition of paleoprecipitation. Isotope values of fluid inclusions formed during peak interglacial periods plot along monsoonal water lines and are indicative of a southern monsoonal moisture source. The last monsoon-dominated period lasting from ∼10,100 to 6,300 years before present was terminated within a few decades in southeastern Arabia. The subsequent reduction in rainfall amount and change from predominantly summer to predominantly winter rainfall had a profound impact on human communities living in this area and triggered migration from inland to coastal areas where resources were more abundant

Laser annealing of silicon on sapphire

Silicon-implanted silicon-on-sapphire wafers have been annealed by 50-ns pulses from a Q-switched Nd : YAG laser. The samples have been analyzed by channeling and by omega-scan x-ray double diffraction. After irradiation with pulses of a fluence of about 5 J cm^–2 the crystalline quality of the silicon layer is found to be better than in the as-grown state

SOAT1 missense variant in two cats with sebaceous gland dysplasia.

Spontaneously arisen hereditary diseases in domestic animals provide an excellent opportunity to study the physiological functions of the altered genes. We investigated two 4-month-old sibling domestic short haired kittens with dry dark debris around the eyes, nose, and ears, dark crusting on the legs and a thin poor hair coat. Skin biopsies revealed abnormal sebaceous gland morphology with lack of normal sebocyte arrangement and differentiation. Hair follicles had a distorted silhouette, interpreted as a change secondary to the observed sebaceous gland dysplasia. Whole genome sequencing on both affected kittens and 65 genetically diverse feline genomes was performed. Filtering for variants that were present in both kittens but absent from the control genomes revealed a homozygous missense variant in SOAT1, encoding sterol O-acyltransferase 1. The protein is localized in the endoplasmic reticulum and catalyzes the formation of cholesteryl esters, an essential component of sebum and meibum. The identified SOAT1:c.1531G > A variant is predicted to change a highly conserved glycine residue within the last transmembrane domain of SOAT1, p.Gly511Arg. In mice, variants in Soat1 or complete knockout of the gene lead to the "hair interior defect" (hid) or abnormal Meibomian glands, respectively. SOAT1:c.1531G > A represents a plausible candidate variant for the observed sebaceous gland dysplasia in both kittens of this study. The variant was not present in 10 additional cats with a similar clinical and histopathological phenotype suggesting genetic heterogeneity. SOAT1 variants should be considered as potential cause in hereditary sebaceous gland dysplasias of humans and domestic animals

Examination of Fluconazole-Induced Alopecia in an Animal Model and Human Cohort.

Fluconazole-induced alopecia is a significant problem for patients receiving long-term therapy. We evaluated the hair cycle changes of fluconazole in a rat model and investigated potential molecular mechanisms. Plasma and tissue levels of retinoic acid were not found to be causal. Human patients with alopecia attributed to fluconazole also underwent detailed assessment and in both our murine model and human cohort fluconazole induced telogen effluvium. Future work further examining the mechanism of fluconazole-induced alopecia should be undertaken