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  • 1
    Electronic Resource
    Electronic Resource
    Transdermal delivery of nicotine in normal human volunteers: a single dose and multiple dose study (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 285-290 
    Details
    ISSN: 1432-1041
    Keywords: nicotine ; transdermal delivery ; dose proportionality ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absorption of nicotine delivered by a transdermal delivery system (TDS) was investigated in two separate studies, (A) a dose proportionality study and (B) a multiple dose study. In the dose range of 15–60 mg nicotine, the AUC and Cmax values were proportional to the dose. The levels achieved were in the same range as reported in smokers, following absorption from nicotine chewing gum. The TDS used in the present study produced sustained levels of nicotine for 24 h. No significant accumulation of nicotine was evident as a result of multiple dose administration using a 30-mg nicotine patch. Absorption of nicotine from the TDS was 80–90% and the rate of delivery was similar during both studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00679785
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  • 2
    Electronic Resource
    Electronic Resource
    Initial stages of the high-temperature corrosion of commercial Fe-Cr-Ni alloys in a carburizing atmosphere of low oxygen partial pressure (1985)
    Springer
    Oxidation of metals 24 (1985), S. 277-314 
    Details
    ISSN: 1573-4889
    Keywords: nucleation ; carburization ; silica layers ; surface pretreatment ; surface-sensitive analytical techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The early stages of corrosion of AISI 314, HK 40, and Alloy 800H have been studied in a strongly carburizing (aC=0.8), weakly oxidizing $$(P_{O_2 } = 10^{ - 30} bar)$$ atmosphere at 1098 K. Samples with electropolished and cold-worked surfaces were exposed for up to 400 min. at temperature, in a conventional corrosion rig or in a reaction vessel which was installed within an X-ray photoelectron spectrometer. The latter facility allowed the effects of the specimen heating rate and the rat of gas flow to be investigated. Examination of the corrosion products was accomplished with the aid of XPS, SEM, TEM, and conventional metallography. Initially, surface layers comprised of α-Cr2O3, (Mn, Cr)3O4, and SiO2 formed, with layer structure, microstructure, and composition being functions of alloy composition and surface condition. Only on the cold-worked surfaces did a well-developed duplex oxide, consisting of an outer, Cr-rich oxide layer and an inner, SiO2 layer, form. In good agreement with the predicted value of 1.9 wt.%, between 1.4 and 2 wt.% Si in the alloy was required to form a complete SiO2 layer. After an incubation period, α-Cr2O3 became unstable and transformed to M7C3; the carbides then grew by diffusion of metal from the alloy substrate. The presence of manganese, as (Mn, Cr)3O4, in the surface oxide influenced the mode of carbide growth, whereas the rate of carbide growth was severely suppressed by a continuous SiO2 layer which acted as a diffusion barrier both to metal and to carbon. It is argued that the SiO2 layer is most effective in reducing carburization when it is free from or contains very few structural defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00657062
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  • 3
    Electronic Resource
    Electronic Resource
    The initial stages of high-temperature corrosion of Fe-Cr-Ni and Cr-Ni alloys in a carburizing atmosphere of low oxygen partial pressure (1985)
    Springer
    Oxidation of metals 24 (1985), S. 47-83 
    Details
    ISSN: 1573-4889
    Keywords: nucleation ; carburization ; transient oxidation ; surface pretreatment ; surfacesensitive analytical techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The initial corrosion reactions on a number of Fe-Cr-Ni and Cr-Ni alloys when exposed in a H2-CH4 gas mixture ofa c =0.8 and $$p_{O_2 } $$ ≈ 10−30 bar at1098 K have been investigated. All alloys were studied with surfaces in boththe cold-worked and electropolished conditions. The experiments, in whichexposure times up to 400 rain were used, were carried out in a conventionalcorrosion rig and also in a small reaction chamber contained within an X-rayphotoelectron spectrometer. The use of XPS, SEM, and TEM showed thattransient α-Cr2O3 layers formed on all alloy surfaces during the heat-up period.On the electropolished surfaces, the oxide layers developed nonuniformly withrespect to microstructure and thickness, whereas homogeneous, compact, andfine-grained α-Cr2O3 layers formed on the cold-worked specimens. Followingan incubation period, M7C3 carbides nucleated on the surfaces; they grew byconsuming the less stable α-Cr2O3 and also through diffusion of metal fromthe alloy substrate. The mode of nucleation of the M7C3 and its rate of growthwere strongly dependent on the character of the transient α-Cr2O3 layers. Afterremoval of α-Cr2O3, carbon ingressed into the substrate where M23C6 wasformed internally. These results are broadly in line with the thermodynamicstability predictions and are discussed in terms of simple models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00659597
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  • 4
    Electronic Resource
    Electronic Resource
    Influence of sulfur on the nature and morphology of carbides formed on the surfaces of Fe-Ni-Cr alloys at high temperatures (1985)
    Springer
    Oxidation of metals 24 (1985), S. 85-97 
    Details
    ISSN: 1573-4889
    Keywords: surface carbides ; Fe-Ni-Cr alloys ; sulfur effects ; morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of sulfur upon surface carbide formation on a range of Fe-Ni-Cr alloys has been investigated at a temperature of 1273 K. The addition of small amounts of H2S, up to 100 ppm (range of $$p_{S_2 } $$ = 2.2×10−12 to 5.5×10 su−11 bar), to a H2-CH4 carburizing atmosphere (ac=0.8) was found to significantly modify the behavior from that normally observed in the sulfur-free environment. The carburization of these alloys in the H2-CH4 atmosphere led to the formation of globular particles of M7C3 on the surface of the alloy, but the addition of H2S affected the type, morphology, and distribution of the surface carbides. Initially, the lower carbon containing M23C6 was formed, which transformed to M7C3 at a rate determined by the concentration of sulfur in the environment. The morphology of the M7C3 was modified by the presence of sulfur, and the carbide exhibited a preferred crystallographic orientation in the [001] direction. Particles of manganese sulfide were formed on the commercial alloys at $$p_{S_2 } $$ 〉 2.3 × 10−11 bar at 1273 K, and these served as nucleation sites for carbides sothat, in contrast to the behavior in sulfur-free conditions, complete surfacecarbide layers were formed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00659598
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  • 5
    Electronic Resource
    Electronic Resource
    Sulfur effects on the internal carburization of Fe-Ni-Cr alloys (1986)
    Springer
    Oxidation of metals 26 (1986), S. 333-350 
    Details
    ISSN: 1573-4889
    Keywords: inhibition ; sulfur effects ; carburization ; Fe-Ni-Cr alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Several commercial and laboratory-cast model austenitic alloys have been exposed in both sulfur-free carburizing environments and also in carburizing atmospheres to which additions of H2S have been made. These studies were concentrated over the temperature range 1223–1323 K at a fixed carbon activity (ac=0.8) with sulfur activities ranging from 2.2×10−12 bar to 1.4×10−9 bar. Under conditions of sulfur adsorption, e.g., $${\text{p}}_{S_{\text{2}} } $$ ≤ 5.5 × 10−11 bar at 1273 K, the blocking of adsorption sites for methane resulted in a transition from the parabolic kinetics observed during sulfur-free carburization to surface controlled linear kinetics. Higher levels of H2S promoted the formation of a surface layer of chromium sulfide which reduced internal carburization but became a problem itself. The role of minor alloying elements has been established and the use of thermodynamic phase stability diagrams in defining the optimum conditions for sulfur inhibition of carburization evaluated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00659340
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  • 6
    Electronic Resource
    Electronic Resource
    A molecular orbital study of the bonding in complexes of lithium with polynuclear aromatic hydrocarbons (1985)
    Springer
    Theoretical chemistry accounts 68 (1985), S. 389-405 
    Details
    ISSN: 1432-2234
    Keywords: Polynuclear aromatic hydrocarbons ; Lithium π complexes ; Graphite-lithium intercalates ; Barriers to migration ; Charge transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In a preliminary investigation of the bonding between the sub-lattices of lithium and of graphite in intercalation compounds, molecular orbital calculations are performed on systems of Li atoms π complexed to one or both sides of polynuclear aromatic hydrocarbons. Energy wells calculated reveal possible sites offered to the Li atoms above the aromatic plane to form complexes in both central and edge regions of the molecule. The influence of additional complexed Li atoms on the migratory tendency of a given Li atom is also investigated, and observations made on the effect of the complexed Li atoms on the C-C bonds of the hydrocarbon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00529059
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  • 7
    Electronic Resource
    Electronic Resource
    Theoretical study of the defect distribution of trivalent cation impurities in MgO (1988)
    Springer
    Journal of materials science 23 (1988), S. 2824-2836 
    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 Atomistic simulation techniques have been used to calculate defect energies for a range of trivalent cation impurities in MgO single crystals. From these, values of the association energies have been estimated for impurity-vacancy aggregates ranging in size from simple impurityvacancy monomers, containing one impurity ion, to large clusters containing up to 24 impurity ions. For the MgO:Cr3+ system, these energies have been incorporated in a mass-action analysis and predictions made of the dependence of the equilibrium distribution of defects on temperature and on the nominal concentration of the dopant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00547457
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