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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 4176-4183 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have studied the formation of surface blisters in 〈100〉 n-type silicon following co-implantation with boron and hydrogen. The silicon substrates had four different n-type dopant levels, ranging from 1014 to 1019 cm−3. These substrates were implanted with 240 keV B+ ions to a dose of 1015 cm−2, followed by a rapid thermal anneal at 900 °C for 30–60 s to force the boron atoms into substitutional lattice positions (activation). The samples were then implanted with 40 keV H+ to a dose of 5×1016 cm−2. The implanted H+ distribution peaks at a depth of about 475 nm, whereas the distribution in the implanted B+ is broader and peaks at about 705 nm. To evaluate the role of the B+ implantation, control samples were prepared by implanting with H+ only. Following the H+ implantation, all the samples were vacuum annealed at 390 °C for 10 min. Blisters resulting from subsurface cracking at depths of about 400 nm, were observed in most of the B+ implanted samples, but not in the samples implanted with H+ only. This study indicates that the blistering results from the coalescence of implanted H into bubbles. The doping with B facilitates the short-range migration of the H interstitials and the formation of bubbles. A comparison of the observed crack depth with the depth of the damage peak resulting from the H+ implantation (evaluated by the computer code TRIM) suggests that the nucleation of H bubbles occurs at the regions of maximum radiation damage, and not at the regions of maximum H concentration. For given values of B+ and H+ doping, the blister density was found to decrease with increasing n-type doping, when the boron is activated. Blister formation was also observed in B+ implanted samples which had not been activated. In this case, the blister density was found to increase with increasing value of n-type doping. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of the American Chemical Society 75 (1953), S. 3882-3887 
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2423-2425 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Diamondlike carbon (DLC) was deposited on silicon using a plasma immersion ion deposition (PIID) method. Inductive radio-frequency plasma sources were used to generate Ar and C2H2 plasmas at low gas pressures ranging from 0.04 to 0.93 Pa. The film stress and hardness were sharply dependent upon bias voltage at an operating pressure of 0.04 Pa. A maximum hardness of 30 GPa and compressive stress of 9 GPa was observed at a pulsed bias of −150 V bias (carbon energy of 80 eV). The mechanical properties of DLC films are correlated with UV Raman peak positions which infer sp3-bonded carbon contents. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 1320-1322 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Electron field emission from allotropes of carbon (graphite, diamondlike carbon, and diamond) have been reported many times in the literature. This work explores the use of ion irradiation for improving electron field emission from carbon fibers. Carbon fibers have been irradiated with H, C, Ar, and Xe ions. Field emission characteristics have been measured as a function of ion dose. A reversible reduction in the required field for a fixed current level has been observed. The critical dose, Dc, defines the dose corresponding to the lowest field necessary to emit a fixed current (5 μA). The critical dose appears to correlate with the nuclear energy loss (collisions with atoms) of the ion in the carbon fiber. Transmission electron microscopy and parallel electron energy loss spectroscopy analysis indicate an amorphous surface, and an increase in the sp3 content of the fiber surface to 20%–30%. A corresponding decrease in the work function is expected and may account for the improvement in electron emission. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 34 (1996), S. 0 
    ISSN: 1745-6584
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Energietechnik , Geologie und Paläontologie
    Notizen: Flow-through microcosms were constructed to conduct ecological experiments on aquifer organisms. The two 5-channel microcosms were simple to construct, were fed by an artesian spring, and maintained close to in situ temperature and O2 concentrations. They were used to test relative microbial colonization of three substrate sizes: silt (0.063 mm), sand (0.9 mm), and gravel (3 mm). After 96 days of incubation, O2 microelectrode measurements revealed the lowest O2 tension in the silt, the highest in the gravel, and intermediate values in the sand. Microbial activity (3[H]-thymidine incorporation) was greatest in the gravel, followed by sand and then silt. Denitrification was greatest in the silt, followed by sand and then gravel. Microbial activity may be greatest with the largest particle size because of increased water exchange through pores, and denitrification may be greatest with the smallest particle sizes because of the occurrence of anaerobic microzones.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of the American Chemical Society 74 (1952), S. 2693-2693 
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of the American Chemical Society 75 (1953), S. 3877-3882 
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 8
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Indirect detections of massive — presumably Jupiter-like — planets orbiting nearby Sun-like stars have recently been reported,. Rocky, Earth-like planets are much more difficult to detect, but clues to their possible existence can nevertheless be obtained from observations of the ...
    Materialart: Digitale Medien
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  • 9
    ISSN: 1572-879X
    Schlagwort(e): partial oxidation of methane ; synthesis gas ; rhodium ; oxygen species ; transient study ; DRIFTS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The nature of surface sites responsible for methane activation and COx formation on Rh catalysts for the partial oxidation of methane to syngas was investigated. The interaction of H4 with Rh-black after oxidative and reductive pretreatments was studied applying (a) pulse experiments at reduced total pressure (10−4 Pa) and 1013 K in the temporal-analysis-of-product (TAP) reactor and (b) in situ DRIFTS at 973 K. The saturation of the metal surface sites with oxygen was found to inhibit methane dissociation. Direct methane oxidation to CO2 on the oxidized surface sites proposed earlier was excluded. Methane is first dissociated on reduced surface sites; the carbon species formed, then, react with surface oxygen to CO2. Rh sites responsible for methane activation are neither related to the formation of the Rh2O3 nor Rh0. Probably the partially oxidized species (Rh+) or highly dispersed Rh3+ entities act as active surface centers for the dissociation of methane. For supported catalyst, such sites are stabilized by the support, which on the other side acts as a source of active oxygen involved in the oxidation of surface carbon and hydrogen.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Der Anaesthesist 47 (1998), S. 330-334 
    ISSN: 1432-055X
    Schlagwort(e): Schlüsselwörter Kolloide ; retikuloendotheliales System ; Gewebespeicherung ; Key words Colloid plasma solutions ; Tissue storage ; Organ failure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Abstract In addition to renal elimination and gastrointestinal metabolism (amylase; splenic and hepatic dextranase) colloid plasma solutions like dextran and hydroxyethyl starch deposit in tissues, especially in the reticuloendothelial system (RES). This tissue storage is limited in time (weeks to months), is influenced by the employed solution and other factors (lysosomes) and has usually no clinical importance (no RES blockade). We report here a case study of a patient with sepsis (lung, liver and kidney failure) who had an overload of the RES with colloids while being treated with dextran (molecular weight 40000 and 70000 daltons) and hydroxyethyl starch (mw 450000 daltons, molar substitution 0,7) for 5 weeks. Autopsy showed parenchymal and reticuloendothelial cells of liver, lung, kidney and spleen with a large amount of colloid mass inclusions and altered organ morphology. This storage may have impaired ventilation, transport of bile acids and renal function. A possible role of tissue storage of colloids in organ failure is discussed.
    Notizen: Zusammenfassung Hydroxyäthylstärke (HAES) und Dextran (DX) werden neben ihrer renalen und gastrointestinalen Ausscheidung und ihrem enzymatischen Abbau (Amylase; Dextranase) zu einem kleinen Prozentsatz in den Zellen des retikuloendothelialen Systems (RES) der Leber, Lunge, Milz und den Lymphknoten gespeichert. Diese Speicherung ist zeitlich begrenzt, von der verwendeten Lösung und von individuellen Faktoren (Lysosomen) abhängig und klinisch im allgemeinen ohne Relevanz. Wir berichten von einem Patienten mit akutem Lungenversagen (ARDS) und Sepsis, bei dem es im Rahmen der Anwendung von HAES mit einem Molekulargewicht (MG) von 450000 Dalton (D) und DX (MG 40000 und 70000 D) zu einer Überladung des RES mit diesen nur langsam abbaubaren Substanzen gekommen ist. Durch die Speicherung der Kolloide bedingte Nebenwirkungen im Sinne eines massiven Alveolarzellkatarrhs mit Austamponierung der Alveolen, einer Hypertrophie der von Kupfferschen Sternzellen, eines Auseinanderdrängens der Leberzellbalken und einer osmotischen Nephrose sowie deren mögliche Relation zu respiratorischer-, Leber- und Niereninsuffizienz werden diskutiert und anhand von Literaturstellen aufgearbeitet.
    Materialart: Digitale Medien
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