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  • 1
    Electronic Resource
    Electronic Resource
    Structural, electrical, and optical properties of SnO2 nanocrystalline thin films grown on p-InSb (111) substrates (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 175-180 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: SnO2 thin films were grown on p-InSb (111) substrates by radio-frequency magnetron sputtering at low temperature. Atomic force microscopy images showed that the root mean square of the average surface roughness of the SnO2 films grown on the InSb (111) substrates with an Ar/O2 flow rate of 0.667 and at a temperature of 200 °C had a minimum value of 2.71 nm, and x-ray diffraction and transmission electron microscopy (TEM) measurements showed that these SnO2 thin films were polycrystalline. Auger electron spectroscopy and bright-field TEM measurements showed that the SnO2/p-InSb(111) heterointerface was relatively abrupt. High-resolution TEM measurements revealed that the SnO2 films were nanocrystalline and that the grain sizes of the nanocystalline films were below 6.8 nm. The capacitance–voltage measurements at room temperature showed that the type and the carrier concentration of the nominally undoped SnO2 film were n type and approximately 1.67×1016 cm−3, respectively, and the current–voltage curve indicated that the Au/n-SnO2/p-InSb diode showed tunneling breakdown. Photoluminescence spectra showed that peaks corresponding to the donor acceptor pair transitions were dominant and that the peak positions did not change significantly as a function of the measured temperature. These results indicate that the SnO2 nanocrystalline thin films grown on p-InSb (111) substrates at low temperature hold promise for new kinds of potential optoelectronic devices based on InSb substrates, such as superior gas sensors and high-efficiency solar cells. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1372159
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  • 2
    Electronic Resource
    Electronic Resource
    Electronic parameters of the two-dimensional electron gas in modulation-doped single quantum wells due to an embedded deep step layer (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 2649-2652 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Shubnikov–de Haas (S–dH) measurements at 1.5 K clearly demonstrated the existence of a two-dimensional electron gas (2DEG) in the modulation-doped Al0.25Ga0.75As/InyGa1−yAs/GaAs single and step quantum wells, and the fast Fourier transformation results for the S–dH data clearly indicated the electron occupation of one subband in the asymmetric single and step quantum wells. While the electron carrier density of the 2DEG in the step quantum well was larger than that in the single quantum well due to the larger conduction-band discontinuities, the mobility of the 2DEG in the step quantum well was smaller than that in the single quantum well because of the interface scattering resulting from the embedded step well. The electron effective mass in the step quantum well was smaller than that in the single quantum well, which was consistent with a smaller mass of the embedded deep step layer. The electronic subband energy, the energy wave function, and the Fermi energy in the InyGa1−yAs step quantum wells were calculated by using a self-consistent method taking into account exchange-correlation effects together with strain and nonparabolicity effects. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1344222
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  • 3
    Electronic Resource
    Electronic Resource
    Thermoelectric and transport properties of CeBiPt and LaBiPt (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 7631-7633 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electrical resistivity ρ, Hall coefficient RH, thermoelectric power S, and thermal conductivity κ have been measured on an antiferromagnet CeBiPt (TN=1 K) and the nonmagnetic analogue LaBiPt, which crystallize in the cubic MgAgAs-type structure. The large values |RH|∼1 cm3/C and ρ∼1.2 mΩ cm at 300 K indicate that both compounds are low-carrier concentration semimetals. The strong temperature dependences of ρ, S, and RH for CeBiPt contrast with the weak temperature dependences for LaBiPt. For CeBiPt, S(T) has a positive maximum of 120 μV/K at 100 K. However, the sign of RH(T) changes from positive to negative with increasing temperature at 170 K, above which S(T) of CeBiPt becomes smaller than LaBiPt. These observations suggest strong dependence of mobility for hole and electron carriers in CeBiPt. In this system, κ(T) is dominated by the phonon contribution, which is consistent with a small carrier concentration. Furthermore, the combination of S, ρ, and κ allows us to estimate the figure of merit for thermoelectric application, Z=1.7×10−4 K−1 at 75 K for CeBiPt. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1357864
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  • 4
    Electronic Resource
    Electronic Resource
    Electronic properties of UIrGe in high magnetic fields (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 7186-7188 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: UIrGe crystallizes in the orthorhombic TiNiSi structure and exhibits a large magnetic anisotropy. Here, we present the results of magnetoresistance and specific-heat studies of single-crystalline UIrGe in magnetic fields up to 18 T applied along the principal axes. The phase boundaries of the zero-field antiferromagnetic phase (TN(approximate)14.1 K) are established, and we find evidence of a field-induced phase above 12.5 T at 2.1 K and 14 T at 2.5 K for magnetic fields applied along the b and c axis, respectively. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1357847
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  • 5
    Electronic Resource
    Electronic Resource
    Electronic property variations due to an embedded potential barrier layer in modulation-doped step quantum wells (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 5089-5092 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electronic property variations of a two-dimensional electron gas (2DEG) in modulation-doped step quantum wells due to an embedded potential barrier were studied by performing Shubnikov–de Haas (SdH), Van der Pauw–Hall-effect, and cyclotron resonance measurements on two kinds of InxGa1−xAs/InyAl1−yAs step quantum wells which were one without and the other with an embedded barrier. The fast Fourier transformation results for the SdH data at 1.5 K indicated the electron occupation of two subbands in both step quantum wells. The total electron carrier density and the mobility of the 2DEG in the step quantum well with an embedded barrier were smaller than those in the quantum well without an embedded barrier. The electron effective masses were determined from the slopes of the main peak absorption energies as functions of the magnetic field, and satisfied qualitatively the nonparabolicity effects in both quantum wells. The electronic subband energies, the wave functions, and the Fermi energies were calculated by using a self-consistent method taking into account exchange-correlation effects together with strain and nonparabolicity effects. These present results indicate that the electronic parameters in modulation-doped InxGa1−xAs/InyAl1−yAs step quantum wells are significantly affected by an embedded barrier. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1454198
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  • 6
    Electronic Resource
    Electronic Resource
    Nanocrystals acting as Coulomb islands operating at room temperature created using a focused ion-beam process (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 120-122 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A Ga+ focused ion-beam (FIB) technique utilizing both lithographic and nanoparticle formation processes has been introduced to create nanocrystals acting as Coulomb islands at room temperature. High-resolution transmission electron microscopy results show that the nanocrystals acting as Coulomb islands are created in the source-drain active layer by using a Ga+ FIB. The results for the drain current and the conductance as functions of the drain voltage with an open gate voltage at room temperature show a Coulomb staircase and conductance oscillations, respectively. Nanoscale particles of Al with an amorphous phase are created in the source-drain channel by the defects due to the radiation effect of the Ga+ FIB, and collisions between Ga+ ions and Al atoms produce secondary electrons, that interact with the nanoparticles, which are acting as Coulomb islands, to form the crystal phase. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1378052
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  • 7
    Electronic Resource
    Electronic Resource
    Sex differences in the discriminative stimulus effects of m-chlorophenylpiperazine and ethanol withdrawal (2000)
    Springer
    Psychopharmacology 149 (2000), S. 170-175 
    Details
    ISSN: 1432-2072
    Keywords: Key words  m-Chlorophenylpiperazine ; Drug discrimination ; Ethanol withdrawal ; Anxiety ; 17β-estradiol ; Sex difference ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: The serotonergic system plays a role in regulation of anxiety and ethanol withdrawal (EW). Nevertheless, few studies have assessed sex differences in serotonergic effects on EW. Objectives: This study examined sex differences in the anxiogenic stimu-li induced by a serotonin (5-HT)1b/2 agonist, meta- chlorophenylpiperazine (mCPP), prior to ethanol and during EW. Methods: Gonadectomized or sham-operated adult male and female rats and 17β-estradiol (2.5 mg, 21-day release, s.c.) -replaced ovariectomized (OVX) rats were trained to discriminate mCPP (1.2 mg/kg, i.p.) from saline in a two-lever choice task for food. Latency to the first lever press and mCPP lever selection were measured following mCPP (0–1.2 mg/kg). Rats then received chronic ethanol-containing liquid diet (6.5%) for 10 days and were tested for mCPP lever selection 12 h and 36 h after removal of ethanol. Results: Fewer sham female and β-estradiol-replaced OVX rats selected the mCPP lever than male or OVX rats, and showed an increased initiation latency after mCPP injection. During EW (12 h and 36 h), fewer sham female and β-estradiol-replaced OVX rats responded on the mCPP-lever after saline injection as well as after mCPP challenge than male or OVX rats. Castration did not alter any response of male rats to mCPP. Conclusions: (1) mCPP discrimination is a useful measure of EW in male and female rats; and (2) sham female and β-estradiol-replaced OVX rats are less sensitive to the discriminative stimulus prior to and during EW, but more sensitive to impaired behavioral initiation induced by mCPP than male or OVX rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002139900353
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  • 8
    Electronic Resource
    Electronic Resource
    A New Method for Solving Branching Problems in Surface Reconstruction (2000)
    Springer
    The international journal of advanced manufacturing technology 16 (2000), S. 259-264 
    Details
    ISSN: 1433-3015
    Keywords: Key words:Branching problem; Cross-section; Distance map; Planar contour; Shape reconstruction; Triangular Bezier patch; Triangulation
    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/s001700050154
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  • 9
    Electronic Resource
    Electronic Resource
    Sex differences in nicotine substitution to a pentylenetetrazol discriminative stimulus during ethanol withdrawal in rats (2000)
    Springer
    Psychopharmacology 149 (2000), S. 235-240 
    Details
    ISSN: 1432-2072
    Keywords: Key words Sex differences ; Nicotine ; Pentylenetetrazol ; Discriminative stimulus ; Ethanol withdrawal ; Anxiety
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Nicotine and ethanol are frequently co-abused in men and women, but few studies compare common stimulus effects produced by these substances between males and females. Objectives: This study compared the anxiety-like behavior induced by nicotine prior to and during ethanol withdrawal in intact male, sham-operated female, and ovariectomized (OVX) rats. Methods: Using an animal model of anxiety, the pentylenetetrazol (PTZ) drug-discrimination assay, rats were trained to discriminate PTZ (16 mg/kg, i.p.) from saline and were subjected to the following tests: (1) PTZ-lever selection at 12 h after termination of ethanol diet (4.5% for 10 days); (2) dose–response tests for nicotine (0.08– 1.3 mg/kg) prior to ethanol and 1.5, 6, and 7 days after ethanol withdrawal. Results: (1) During acute ethanol withdrawal (12 h), more male rats (43.4%) responded on the PTZ lever than OVX (29%) or sham female (15.3%) rats. (2) For nicotine dose–response tests, more male rats (70%) selected the PTZ lever than OVX (37.5%) or sham female (50%) rats prior to ethanol. At 1.5 days, nicotine fully generalized to the PTZ stimulus in male (100%) and OVX (90%), but only partially in sham female (50%) rats. At 6 days and 7 days after ethanol withdrawal, the PTZ-lever selection decreased, but more male rats (78%) tended to respond on a PTZ lever than OVX (63.6%) or sham female rats (62.5%). Conclusions: Acute nicotine produces anxiety-like behavior similar to that of PTZ in male and female rats, and this effect of nicotine is intensified during ethanol withdrawal in male and OVX rats, but not in sham female rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130000392
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  • 10
    Electronic Resource
    Electronic Resource
    Polymerisation in supported bilayers (2000)
    Springer
    Colloid & polymer science 278 (2000), S. 1114-1118 
    Details
    ISSN: 1435-1536
    Keywords: Key words Organically modified clay minerals ; Polymerisation ; Supported bilayers ; Dioctadecyldimethylammonium bromide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The intercalation of the twin-tailed amphiphilic dioctadecyldimethylammonium (DODA) ions in smectite clay minerals provides a well-defined supported bilayer system. Polymerisation of styrene in these robust model bilayers allows one to focus on the effect of the constrained medium on the polymerisation process and the polymer. Small-angle X-ray scattering analysis and differential scanning calorimetry data indicated that the polymerisation of styrene in DODA–montmorillonite leads to phase separation between polystyrene and the surfactant matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960000378
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