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  • 1
    Electronic Resource
    Electronic Resource
    Use of a valved, solid phosphorus source for the growth of Ga0.5In0.5P and Al0.5In0.5P by molecular beam epitaxy (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 342-344 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on a new method for the generation of phosphorus beams in molecular beam epitaxy: the use of a valved, solid cracker source. The valved solid source avoids previous difficulties associated with the use of solid phosphorus, and provides an attractive alternative to the use of phosphine. The use of red phosphorus does not interfere with the subsequent growth of high quality arsenides in the same growth chamber. The performance of this valved phosphorus source is illustrated by the growth of two ternary phosphides, Ga0.5In0.5P and Al0.5In0.5P. The quality of the phosphides reported here is comparable to the best results reported by other growth techniques. The effects of composition, growth temperature, and P2 flux on the films' characteristics are reported. Indium desorption during growth is found to be substantially greater in AlInP than in GaInP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105590
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  • 2
    Electronic Resource
    Electronic Resource
    Gastric retention of sucralfate gel and suspension in upper gastrointestinal diseases (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Alimentary pharmacology & therapeutics 7 (1993), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This study was designed to compare by scintigraphy the gastric retention of a new dosage form of sucralfate as gel (Gastrogel) with that of sulcralfate suspension in 25 patients with upper gastrointestinal symptoms referred for routine endoscopy. After endoscopy 4 subgroups were defined: macroscopically normal mucosa (n= 7), antral gastritis and/or erosions (n= 6), gastric ulcer (n= 6) and duodenal ulcer (n= 6). Each patient received either sucralfate gel or sucralfate suspension in equivalent doses (5 ml containing 1 g sucralfate). Both formulations were labelled with 111 MBq 99m Tc-DTPA before administration. The mean value of t½ in the total group was significantly longer when patients were taking sucralfate gel (61.6 min) compared to sucralfate suspension (33.8 min) (P 〈 0.001). The mean values of t½ were significantly longer for sucralfate gel compared to sucralfate suspension also among the subgroups (macroscopically normal P 〈 0.02, antral gastritis P 〈 0.05, gastric ulcer P 〈 0.02 and duodenal ulcer P 〈 0.05). After 2 and 3 hours, the percentage residual activity in the gastric area was significantly higher following administration of sucralfate gel compared to sucralfate suspension. This study has shown that, compared to sucralfate suspension, sucralfate gel persists longer in the stomach of patients with gastritis and peptic ulcer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2036.1993.tb00129.x
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  • 3
    Electronic Resource
    Electronic Resource
    Parietaria pollen allergens (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Allergy 53 (1998), S. 0 
    Details
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1398-9995.1998.tb03791.x
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  • 4
    Electronic Resource
    Electronic Resource
    1,2-Dichloropropane (DCP) toxicity is correlated with DCP-induced glutathione (GSH) depletion and is modulated by factors affecting intracellular GSH (1990)
    Springer
    Archives of toxicology 64 (1990), S. 459-465 
    Details
    ISSN: 1432-0738
    Keywords: Toxicity-1,2-Dichloropropane-Glutathione-N-acetylcysteine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Acute 1,2-dichloropropane (DCP) poisoning in humans is relatively frequent in Italy, where DCP is widely diffused as a constituent of commercial solvents and dry cleaners. In this study we have investigated the effects of DCP on intracellular glutathione (GSH) content in main target tissues of male Wistar rats, i.e. liver, kidney and blood, in order to establish if a correlation between DCP-induced GSH depletion and tissue damage exists. Administration of DCP (2 ml/kg body weight orally) caused a dramatic loss of tissue GSH occurring 24 h after DCP intoxication, followed by a slow restoration approaching physiological levels after 96 h. GSH depletion was associated with a marked increase in serum GOT, GPT, 5′-nucleotidase, gamma-glutamyl transpeptidase, alkaline phosphatase, urea and creatinine, and a significant degree of hemolysis. When animals were pretreated with a GSH depleting agent, buthionine-sulfoximine (BSO) (0.5 g/kg body weight) i. p. 4 h before DCP intoxation, an increase of overall mortality was found, significantly different from the group of animals treated with DCP alone. On the contrary, the administration of a GSH precursor, N-acetylcysteine (NAC) i. p. (250 mg/kg body weight) 2 and 16 h after DCCP intoxication prevented the dramatic loss of cellular GSH and reduced the extent of injury in target tissues, as demonstrated by laboratory indices. Furthermore, statistical analysis of the data revealed a correlation between: (1) depletion of liver GSH and increase in serum GOT, GPT, 5′-nucleotidase, (2) depletion of kidney GSH and increase in serum urea and creatinine and (3) depletion of blood GSH and the occurence of hemolysis. Our findings demonstrate that GSH plays a critical role in modulating the toxicity of DCP. They also highlight the protective role of NAC and suggest that this glutathione precursor could rationally be employed in DCP poisoning in humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01977627
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  • 5
    Electronic Resource
    Electronic Resource
    Atmosphere effects in the processing of silicon carbide and silicon oxycarbide thin films and coatings (1994)
    Springer
    Journal of sol gel science and technology 2 (1994), S. 601-604 
    Details
    ISSN: 1573-4846
    Keywords: silicon carbide ; silicon oxycarbide ; thin film
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Silicon carbide and silicon oxycarbide films were prepared from solutions of polycarbosilane and methyldimethoxysilane + tetraethoxysilane, respectively, and deposited on different substrates (Si wafers, stainless steel plates, sapphire and SiC fibers). The coatings were heated at different temperatures and in different atmospheres, such as regular grade argon, ultra high purity and argon vacuum. The films were characterized using different techniques (FT-IR, XRD, SIMS, Ellipsometry). The influence of the processing parameters (heat treatment temperature and atmosphere) on the final microstructure of the coatings is discussed in this article.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00486317
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  • 6
    Electronic Resource
    Electronic Resource
    New materials based on the reaction of cyclo- and poly-(organo phosphazenes) with SiO2, TiO2 and ZrO2 precursors (1994)
    Springer
    Journal of sol gel science and technology 2 (1994), S. 109-114 
    Details
    ISSN: 1573-4846
    Keywords: hybrid material ; organic-inorganic system ; phosphazene ; polymer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new class of organic-inorganic materials can be prepared, based on inorganic networks and cycloor poly-(organophosphazenes). Poly(organophosphazenes) are polymers characterized by many interesting technological properties. This report is based on a investigation on the reactivity of SiO2, TiO2 and ZrO2 precursors with different phosphazene compounds functionalized with hydroxyl groups, to prepare materials with a hybrid structure. The synthesis of these systems was studied in different experimental conditions. Evidences on the structures and properties of these materials will be presented on the basis of FTIR, SEM and thermal analysis characterization results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00486222
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  • 7
    Electronic Resource
    Electronic Resource
    Joining of reaction-bonded silicon carbide using a preceramic polymer (1998)
    Springer
    Journal of materials science 33 (1998), S. 2405-2412 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Ceramic joints between reaction-bonded silicon carbide (RBSiC) were produced using a preceramic polymer (GE SR350 silicone resin) as joining material; samples were heat treated in an argon flux at temperatures ranging from 800–1200°C without applying any pressure. The strength of the joints was determined by four-point bending, shear and indentation tests. Microstructural and microchemical analyses were performed by optical microscopy, SEM, TEM and AEM. The room-temperature strength of the joints increased with the joining temperature. Maximum values as high as 220 MPa in bending and 39 MPa in shear tests were reached for samples joined at 1200°C. No detectable residual stresses were observed both in the joining material and the joined parts, and the fracture mechanism was nearly always cohesive. The joint thickness was shown to depend on the processing temperature, and ranged from about 2–7 μm. The joining material was a silicon oxycarbide amorphous ceramic, with no oxygen diffusion occurring between this and the RBSiC joined parts. The lack of compositional gradients, precipitates or reaction layers indicate that the SiOC ceramic acted as an inorganic adhesive, and that the joining mechanism involved the direct formation of chemical bonds between the RBSiC parts and the joining material. © 1998 Chapman & Hall
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004312109836
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  • 8
    Electronic Resource
    Electronic Resource
    Alkaline ion sensitivity of insulator-silicon structures with glass membranes prepared by the sol-gel technique (1991)
    Springer
    Journal of materials science 10 (1991), S. 1129-1131 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00744103
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  • 9
    Electronic Resource
    Electronic Resource
    Ceramic coatings by ion irradiation of polycarbosilanes and polysiloxanes: Part I Conversion mechanism (1997)
    Springer
    Journal of materials science 32 (1997), S. 6163-6173 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Changes of composition and structure of various types of polysiloxanes and polycarbosilanes when submitted to irradiation with ions of increasing mass, were analysed by means of several ion-beam analytical techniques, Raman and Fourier transform–infrared spectroscopies. Ion irradiations is as efficient as annealing at temperatures above 1000°C for releasing hydrogen from these organic–inorganic polymers, and the radiolytic evolution of hydrogen is selective, whereas methane, silanes and carbon monoxide are also evolved during heat treatments. The kinetics of the polymer conversion into amorphous ceramics depends strongly on the linear density of energy transferred by ions to electron shells of target atoms, according to the ion energy per nucleon and to the nature of the side groups. Some of the carbon atoms segregate in clusters exhibiting a diamond-like hybridization state, in contrast to the clusters of turbostratic graphite formed in pyrolysed films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018664406046
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  • 10
    Electronic Resource
    Electronic Resource
    Ceramic coatings by ion irradiation of polycarbosilanes and polysiloxanes: Part II Hardness and thermochemical stability (1997)
    Springer
    Journal of materials science 32 (1997), S. 6175-6182 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The hardnesses of polycarbosilane and polysiloxane coatings subjected to irradiation with increasing doses of He, C and Au ions were measured by means of nanoindentation tests. Diamond-like carbon clusters which are formed during irradiation enhance the hardnesses of the ceramic films which reach in some cases three times that of conventionally annealed specimens. When submitting irradiated films to an additional anneal, the clusters resulting from the segregation of atoms from methyl groups remain more diamond like than those formed directly by radiolysis of phenyl rings, especially when the radiolytic transformation is incomplete (the film having received a low irradiation dose). Moreover, owing to the selective release of hydrogen and the recombination of free radicals at room temperature, no evolution of CHx and COx nor oxidation of unpaired Si atoms occurs during this post-irradiation anneal, contrary to the observations during direct thermal conversion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018616622885
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