Formation and Characterization of Aluminium Contacts to n-type Silicon

Samples were prepared by performing phosphorus diffusions with POCl3 on Sb doped (100) silicon wafers. 99.9% (3N) purity Al or 99.999% (5N) purity Al dots of diameter 0.7 mm and thickness between 0.2 µm or 1.0 µm were then deposited onto quarters of these wafers. The quarters were then subsequently cleaved into 1 cm2 pieces which were annealed at temperatures ranging from 400?C to 650?C for durations of time between 10 minutes and 2 hours. The speed with which these samples were cooled was also varied. After annealing, 3N Al or 5N Al was then deposited on the rear of the samples to a thickness of 1 µm to ensure a low resistance ohmic contact was formed on the rear. Characterisation of these contacts was carried out by measuring the IV characteristics of the contacts and by removing the Al from the front and making observations of the surface topology under an optical microscope and/or by utilizing a scanning electron microscope (SEM). Also, secondary ion mass spectrometry (SIMS) was used to check the diffusion profile of Al, P, and the concentration of Sb dopant in the wafers. Results showed that samples which had 0.3 µm Al deposited in dots on the front, when sintered at temperatures over the eutectic temperature, exhibited rectifying properties evidenced by IV curves characteristic of diodes with turn on voltages of 0.6 mV. The corresponding samples with 1.0 µm appeared to have similar IV curves. However, the turn on voltage was about 0.5 mV. On inspection of the interface, the 0.3 µm Al deposited samples appeared to have formed large, well rounded holes in the silicon and the 1.0 µm Al deposited samples showed localized spiking and no large, well rounded holes. The samples that were sintered at less than the eutectic temperature, showed very poor rectifying contact properties in their IV curves and their interfaces varied from minimal pitting at lower temperatures to large degrees of pitting at higher temperatures

Vitamin D receptor regulates intestinal proteins involved in cell proliferation, migration and stress response

BACKGROUND: Genome-wide association studies found low plasma levels of 25-hydroxyvitamin D and vitamin D receptor (VDR) polymorphisms associated with a higher prevalence of pathological changes in the intestine such as chronic inflammatory bowel diseases. METHODS: In this study, a proteomic approach was applied to understand the overall physiological importance of vitamin D in the small intestine, beyond its function in calcium and phosphate absorption. RESULTS: In total, 569 protein spots could be detected by two-dimensional-difference in-gel electrophoresis (2D-DIGE), and 82 proteins were considered as differentially regulated in the intestinal mucosa of VDR-deficient mice compared to that of wildtype (WT) mice. Fourteen clearly detectable proteins were identified by MS/MS and further analyzed by western blot and/or real-time RT-PCR. The differentially expressed proteins are functionally involved in cell proliferation, cell adhesion and cell migration, stress response and lipid transport. Mice lacking VDR revealed higher levels of intestinal proteins associated with proliferation and migration such as the 37/67 kDa laminin receptor, collagen type VI (alpha 1 chain), keratin-19, tropomyosin-3, adseverin and higher levels of proteins involved in protein trafficking and stress response than WT mice. In contrast, proteins that are involved in transport of bile and fatty acids were down-regulated in small intestine of mice lacking VDR compared to WT mice. However, plasma and liver concentrations of cholesterol and triglycerides were not different between the two groups of mice. CONCLUSION: Collectively, these data imply VDR as an important factor for controlling cell proliferation, migration and stress response in the small intestine

Microhabitats of benthic foraminifera - a static concept or a dynamic adaption to optimize food aquisition?

In situ observations of microhabitat preferences of living benthic foraminifera are presented from sediments of the Norwegian-Greenland Sea, the upwelling area off northwestern Africa and the shallow-water Kiel Bight (Baltic Sea). Certain foraminiferal species (e.g.Cibicidoides wuellerstorfi andRupertina stabilis) can be regarded as strictly epibenthic species, colonizing elevated habitats that are strongly affected by bottom water hydrodynamics. Large epibenthic foraminifera (e.g.Rhabdammina abyssorum andHyperammina crassatina) colonize the sediment surface in areas where strong bottom currents occur and might have by virtue of their own size an impact on the small-scale circulation patterns of the bottom water. Motile species changing from epifaunal to infaunal habitats (e.g.Pyrgo rotalaria, Melonis barleeanum, Elphidium excavatum clavatum, Elphidium incertum, Ammotium cassis andSphaeroidina bulloides) are regarded here as highly adaptable to changes in food availability and/or changing environmental conditions. This flexible behaviour is regarded as a dynamic adaptation to optimize food acquisition, rather than a static concept leading to habitat classification of these ubiquitous rhizopods

Handbuch der pharmazeutisch-mathematischen Physik und Chemie : zum Selbststudium für angehende Chemiker, Aerzte und Apotheker : nebst einer verschiebbaren chemischen Aequivalenten-Scale und 28 tabellarischen Uebersichten, sämmtlich mit den nöthigen Erläuterungen über ihre Einrichtung, Gebrauchs- und Nutzungsart versehen

von Wilhelm Weinhol

Luftschifffahrt und Maschinenwesen : Nachweisung eines neuen Bewegungsmittels, in Anwendung auf den Betrieb und die Bewegung von Maschinen, Fahrzeugen, Geschossen und Projectilien aller Art mächtiger und vortheilhafter, als alle seither in Gebrauch genommene Kraftäusserungen ...

von Wilh. Weinhol

Technisch-chemisches Handbuch der Erforschung, Ausscheidung und Darstellung des, in den Künsten und Gewerben gebräuchlichen, metallischen Gehalts der Mineral-Körper : unter steter Berücksichtigung sämmtlicher, bis jetzt in der Chemie gemachten Erfahrungen; zum Selbststudium, besonders für angehende Hüttenbeamte, Cameralisten etc. ...

entworfen vom Dr. W. Weinhol

Schicksale einer Proletarierin : eine Neujahrsgabe für reiche Leute

erzählt von Albert Weinhol