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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 732-742 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The phosphorus redistribution in a WSi2/polycrystalline-silicon structure after furnace annealing between 600 and 1000 °C was studied. When P is initially introduced into the polycrystalline-silicon, a secondary ion mass spectroscopy analysis shows a nearly equidistribution of the dopant within the sandwich. When the silicide layer is phosphorus implanted, it has been clearly shown that with the refractory metal the dopant forms a tungsten phosphide compound more stable than WSi2 up to a critical temperature Tc. The stability of the phosphide increases with the implanted dose. A complete characterization of the additional phase was obtained by thermal annealing of W-Si-P powders. Several other interesting features on the redistribution of the dopant in the polycrystalline-silicon/silicide structure have been established and discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 2760-2764 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Under ultrahigh vacuum conditions, molybdenum disilicide has been obtained by electron gun evaporation of molybdenum on heated monocrystalline silicon substrate. Depending on the deposition temperature, the resulting thin film is composed of tetragonal disilicide or of a mixture of hexagonal and tetragonal disilicide. Preferential orientations of MoSi2 have been observed for both phases grown on (100) silicon substrate heated at 550, 650, and 750 °C. Further annealing does not improve the crystallographic orientation of the materials.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1591-1593 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin, silicon-rich tungsten silicide layers, deposited using the co-sputtering technique and annealed within the temperature range 750–950 °C, were investigated using the acoustic material signature technique, transmission electron microscopy, and the Rutherford backscattering technique. The effective elastic constants were determined from the dispersion curves calculated using a Tiersten model [J. Appl. Phys. 40, 2 (1969)] and fitted to the experimental dispersion data. It is shown that for the annealing temperatures used the elastic properties of thin silicide films are correlated with the annealing temperature-dependent content of the excess silicon present within the grain boundaries.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 2198-2200 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We prepared Er silicide films on (111) Si by (1) deposition of Er and contact reaction at 380 °C or (2) vacuum codeposition of Er and Si maintaining the flux ratio close to 1:2. Subsequent annealing at temperatures up to 900 °C yielded monocrystalline, continuous layers, whose properties were examined by means of low-energy electron diffraction, Auger spectroscopy (in situ) and (ex situ), x-ray and high-energy electron diffraction, and Rutherford backscattering. Method 2 was shown to give better results. The films had a hexagonal AlB2 structure with Si deficiency up to 20%, which is consistent with formerly published results on Si vacancy formation. We showed that the film structure had an additional periodicity of 15 A(ring) along the 〈110〉 orientations of Si and of 6 A(ring) along the 〈112〉 orientations of Si. We demonstrated a feasibility of Si reepitaxy on Er silicide deposited on (111) Si, thus fabricating a novel semiconductor/metal/semiconductor epitaxial heterostructure.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 95 (1988), S. 195-199 
    ISSN: 1432-2072
    Keywords: Drug discrimination ; Scopolamine cue ; Muscarinic agonists ; Muscarinic antagonists ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The discriminative stimulus properties of scopolamine, a potent antagonist at muscarinic receptors, were used for testing the discriminative effects of drugs known to act on cholinergic transmission. Rats were trained in a standard two-bar operant conditioning procedure with food as the reinforcer, according to a FR10 schedule. The training dose of scopolamine was progressively reduced from 0.25 mg/kg SC to the low dose of 0.062 mg/kg SC. Scopolarmine yielded an accurate discrimination in all the six rats tested. The generalization gradient resulted in an ED50 of 0.027 mg/kg. The scopolamine cue lasted for 1 h and was of central origin, since it was not mimicked by scopolamine methylbromide. The scopolamine stimulus generalized to atropine and trihexyphenidyl (respective ED50 values 2.20 and 0.21 mg/kg SC). Atropine depressed rate of responding, while trihexyphenidyl did not. Antagonism experiments with both direct agonists at the muscarinic receptor (arecoline and oxotremorine) and indirect agonists, i.e., inhibitors of the acetylcholine esterase [physostigmine and tetrahydroaminoacridine (THA)], led to inconsistent results. Increasing the doses of the agonists in order to block the scopolamine cue may be limited by their rate suppressant effect on responding. Based upon previously published results, it is suggested that the muscarinic agonist cue is more useful than the antagonist cue for investigating muscarinic transmission.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2072
    Keywords: Social memory ; Cholinomimetic drugs ; Nootropic drugs ; Benzodiazepine inverse agonists ; Psychostimulants ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The recognition of an unfamiliar juvenile rat by an adult rat has been shown to imply short-term memory processes. In this study the effect of various psychotropic drugs on this investigatory behaviour was examined. The procedure was as follows: an unfamiliar juvenile rat was placed in the home cage of an adult rat for 5 min. The time spent by the adult rat in investigating the juvenile was recorded. The adult rat was then immediately treated with vehicle or test compounds, and was again exposed for 5 min to the same juvenile 2 h later. At this time point vehicle-treated rats no longer recognized the juvenile rat, i.e. the time of investigation was similar to that observed during the first presentation. Arecoline (1 and 3 mg/kg IP), physostigmine (0.05 and 0.1 mg/kg SC), RS86 (0.5 mg/IP) and nicotine (0.125 and 0.5 mg/kg IP) reduced in a dose-dependent fashion the time spent in investigating the juvenile during the second exposure. This result cannot be attributed to nonspecific effects, since it was not observed when a different juvenile was used for the second exposure. The effect of arecoline was reversed by scopolamine, but not by methylscopolamine. Aniracetam reduced investigatory behaviour at the dose of 50 mg/kg IP. FG 7142 (5 mg/kg IP) and β-CCM (0.4 mg/kg IP) were also active and their effect was reversed by Ro 15-1788. dl-Amphetamine (0.5 and 1 mg/kg IP), nomifensine (1.25–10 mg/kg IP) and strychnine (0.25 and 0.5 mg/kg IP) were ineffective or reduced this behaviour unspecifically. Social recognition may therefore represent a useful and simple test to detect compounds which enhance short-term, olfactory, memory and to assess in the same animals the specificity of this activity.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 98 (1989), S. 286-288 
    ISSN: 1432-2072
    Keywords: IP pirenzepine ; Passive avoidance ; Brain penetration ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract When injected IP, the M1 muscarinic receptor antagonist pirenzepine dose-dependently induced a deficit in passive avoidance learning in rats. This activity was optimal at 75 mg/kg injected 1 h before the acquisition session. The deficit induced by pirenzepine was antagonized by oxotremorine (0.03–0.3 mg/kg SC) and physostigmine (0.1 mg/kg SC), but not neostigmine. By comparison, under the same experimental conditions, physostigmine and oxotremorine also antagonized the deficit induced by an equipotent dose of scopolamine (0.5 mg/kg IP), although the activity of physostigmine appeared stronger against scopolamine than against pirenzepine. These results suggest that pirenzepine could produce a centrally-mediated behavioural disruption when injected systemically.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 95 (1988), S. 553-555 
    ISSN: 1432-2072
    Keywords: Drug discrimination ; Physostigmine ; M1 receptors ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats were trained to discriminate 0.10 mg/kg SC physostigmine from saline in a two-lever food-reinforced task. There was generalization to the acetylcholine esterase inhibitor THA as well as to the muscarinic receptor agonists arecoline, oxotremorine and RS 86, but not to neostigmine or nicotine. The physostigmine cue was blocked by SC scopolamine hydrobromide and by ICV pirenzepine, but not by scopolamine methylbromide or by mecamylamine. These antagonism studies suggest that the discriminative cue elicited by physostigmine might be mainly mediated by central M1 receptors.
    Type of Medium: Electronic Resource
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