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  • 1
    Electronic Resource
    Electronic Resource
    Computer aided optimization of the experimental conditions for the isocratic reversed-phase high-performance liquid chromatographic separation of hormonal steroids
    Amsterdam : Elsevier
    Journal of Chromatography A 552 (1991), S. 103-111 
    Details
    ISSN: 0021-9673
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0021-9673(01)95926-6
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  • 2
    Electronic Resource
    Electronic Resource
    Quantification of polyimide carbonization after laser ablation (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 3659-3666 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polyimide was irradiated with a XeCl excimer laser (308 nm) and the ablated area and its surrounding were studied using transmission electron microscopy (TEM) and confocal Raman microscopy. Ring-like structures surrounding the ablated area were detected at all fluences. At fluences lower than 250 mJ/cm−2 the formation of conical structures was observed within the irradiated area. The width of the rings increases with fluence and only slightly with the number of pulses. The rings consist mainly of polycrystalline carbon with a relatively high bond angle disorder, with thickness decreasing radially from the crater edge. The thickness of the deposited carbon was determined from TEM analysis and calculated from the intensity ratios of Raman bands assigned to carbon and polyimide using a two layer model. Comparing the two results an estimate of the absorption coefficient of the deposited carbon could be obtained. On top of the cone structures carbon was detected with a higher degree of crystallinity and lower bond angle disorder as compared to the material deposited outside the crater. With energy dispersive x-ray analysis, calcium could be detected on top of the cones. Therefore, it can be assumed that the Ca impurities are causing the cone structures. The higher crystallinity of the carbon inside the irradiated area is probably due to a tempering-like process on top of the Ca compound which is heated upon laser irradiation or to a mixture of growth mechanisms similar to the ones suggested for the formation of carbon nanotubes on metal particles and carbon nanohorns without metal catalysis. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1289516
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  • 3
    Electronic Resource
    Electronic Resource
    Optical behavior of reactive sputtered carbon nitride films (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 2812-2817 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Carbon nitride films with β-C3N4 crystals were grown on Si(100) substrates using reactive sputtering. The deposition was achieved using a graphite target in an argon/nitrogen plasma. Different nitrogen (N2) fractions and substrate biases were used while the other parameters remained fixed. Atomic force microscopy (AFM) was used to measure the surface roughness and surface morphology. X-ray photoelectron spectroscopy (XPS) and ellipsometry measurements were carried out to analyze nitrogen content, chemical bonding state, and optical properties. AFM measurement indicated the surface roughness ranged from 0.2 to 2.5 nm. From XPS data, maximum N/C ratio of 0.5 was achieved in the films. The XPS C 1s spectrum for C(Single Bond)N bond is at 287.32 eV while the N 1s spectrum has a corresponding peak of C(Single Bond)N bond at 398.46. At N2 fraction from 0.6–0.8 and bias from −120 to −200 V, high sp3/sp2 ratio and more β-C3N4 crystals were obtained. Consequently, the films grown at these conditions had high optical band gap. The optical band gap ranged from 1.35 to 2.5 eV. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1446224
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  • 4
    Electronic Resource
    Electronic Resource
    Formation of β-C3N4 crystals at low temperature (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 4099-4104 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Carbon nitride films with β-C3N4 crystals of 200 nm grain size were grown on Si (100) substrates using magnetron sputtering. Reactive deposition was achieved using a graphite target in an argon/nitrogen plasma at room temperature. These films were characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy. Micro level β-C3N4 crystal grains were observed with TEM. According to calculations from electron diffraction pattern, these crystalline structures were in a good agreement with hypothetical b-C3N4 structure. AFM measurement also indicated the grain size was around 200 nm and the carbon nitride films had low surface roughness. From XPS data, maximum N/C ratio of 0.5 was achieved in the films. XPS spectra of the films typically showed three peaks in the C 1s core level spectrum (centered at 284.6, 285.9, and 287.2 eV) and two peaks in the N 1s core level spectrum (centered at 398.7 and 400.2 eV). This indicates that there are two types of C–N bonds; N is bonded to sp2- or sp3-coordinated C atoms in the as-deposited films. FTIR spectra showed three absorption bands in the range of 1000–3000 cm−1. The absorption band around 2367 cm−1 can be attributed to C(Triple Bond)N nitrile bond. The absorption bands around 1559 and 1201 cm−1 demonstrate the existence of C(Double Bond)N (sp2) and C–N (sp3) bonds. Analysis of Raman spectrum further demonstrated the coexistence of sp, sp2, and sp3 bonds. All of XPS, FTIR, and Raman measurements showed the presence of fourfold coordinated β-C3N4 crystals in the films, which is in good agreement with TEM and electron diffraction results. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1327603
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  • 5
    Electronic Resource
    Electronic Resource
    Tunneling spectroscopy study of spin-polarized quasiparticle injection effects in cuprate/manganite heterostructures (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 5350-5352 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Scanning tunneling spectroscopy was performed at 4.2 K on epitaxial thin-film heterostructures comprising YBa2Cu3O7−δ and La0.7Ca0.3MnO3, to study the microscopic effects of spin-polarized quasiparticle injection from the half-metallic ferromagnetic manganite on the high Tc cuprate superconductor. The quasiparticle tunneling characteristics observed were consistent with d-wave pairing symmetry, with a gap-maximum Δ0(approximate)22 meV, up to at least 35 mA (7×103 A/cm2) injection. Spectral smearing observed at higher injections could be fitted to elevated effective quasiparticle temperatures, even though negligible sample heating was detected by in situ thermometry. The overall spectral evolution with the injection current also appears to be nonthermal in character, showing a nonmonotonic change in both the zero-bias tunneling conductance and the area under the conductance spectrum. We discuss general implications of these results for the scenario of dynamic pair breaking by a nonequilibrium distribution of spin-polarized quasiparticles. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370249
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of lattice distortion on the physical properties and surface morphology of magnetoresistive perovskite epitaxial films : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 5499-5501 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of lattice distortion on the physical properties of La0.7Ca0.3MnO3 epitaxial films are investigated. Our results suggest that larger substrate-induced lattice distortion gives rise to larger zero-field resistivity and larger negative magnetoresistance. Similar effects are also observed in samples of different thicknesses and on the same substrate material, with larger resistivity and magnetoresistance associated with thinner samples. In addition to x-ray diffraction spectroscopy, the degrees of lattice distortion in different samples are further verified by the surface topography taken with a low-temperature scanning tunneling microscope. Quantitative analyses of the transport properties suggest that the high-temperature (T→TC) colossal magnetoresistance (CMR) in the manganites is consistent with the conduction of lattice polarons induced by the Jahn–Teller coupling, and that the low-temperature (T(very-much-less-than)TC) magnetoresistance may be attributed to the magnetic domain wall scattering. In contrast, the absence of the Jahn–Teller coupling and the large conductivity in La0.5Ca0.5CoO3 epitaxial films yield much smaller negative magnetoresistance, which may be attributed to disorder-spin scattering. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364580
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  • 7
    Electronic Resource
    Electronic Resource
    Indium oxide diffusion barriers for Al/Si metallizations (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 2644-2646 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Indium oxide (In2O3) films were prepared by reactive rf sputtering of an In target in O2/Ar plasma. We have investigated the application of these films as diffusion barriers in 〈Si〉/In2O3/Al and 〈Si〉/TiSi2.3/In2O3/Al metallizations. Scanning transmission electron microscopy together with energy dispersive analysis of x ray of cross-sectional Si/In2O3/Al specimens, and electrical measurements on shallow n+-p junction diodes were used to evaluate the diffusion barrier capability of In2O3 films. We find that 100-nm-thick In2O3 layers prevent the intermixing between Al and Si in 〈Si〉/In2O3/Al contacts up to 650 °C for 30 min, which makes this material one of the best thin-film diffusion barriers on record between Al and Si. (The Si-Al eutectic temperature is 577 °C, Al melts at 660 °C.) When a contacting layer of titanium silicide is incorporated to form a 〈Si〉/TiSi2.3/In2O3/Al metallization structure, the thermal stability of the contact drops to 600 °C for 30 min heat treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100541
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  • 8
    Electronic Resource
    Electronic Resource
    Tunneling evidence of half-metallicity in epitaxial films of ferromagnetic perovskite manganites and ferrimagnetic magnetite : The 7th joint MMM-intermag conference on magnetism and magnetic materials (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 7366-7368 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Direct evidence of half-metallic density of states is observed by scanning tunneling spectroscopy of ferromagnetic La0.7Ca0.3MnO3 and La1−xSrxMnO3 (x=0.3, 0.33) epitaxial films which exhibit colossal magnetoresistance (CMR). At 77 K, well below the Curie temperatures, the normalized tunneling conductance (dI/dV)/〈I/V〉 for all samples exhibits similar pronounced peak structures, consistent with the spin-split density of states spectra for the itinerant bands in the ferromagnetic state. The exchange energy splitting between the majority and minority spins, as well as an apparent energy gap near the Fermi level, show variations with the chemical composition and the temperature. For comparison, the tunneling spectrum of a half-metallic ferrimagnet Fe3O4 is also studied. The characteristic spin-split density of states spectrum is observed, and the similarities and differences of Fe3O4 compared with the perovskite manganites are discussed. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367799
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  • 9
    Electronic Resource
    Electronic Resource
    Free-standing single-crystalline chemically vapor deposited diamond films (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 2216-2218 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Free-standing chemically vapor deposited (CVD) single-crystalline diamond films have been fabricated by a sequence of processes including high energy ion implantation, microwave plasma enhanced chemical vapor deposition, and the final separation of the diamond epilayer from the substrate by heating in oxygen. The homoepitaxial diamond film separated from the substrate is about 15 μm thick. It is flat and transparent, and exhibits a sharp diamond Raman peak without nondiamond background signals. This process is promising for mass production of large-area single-crystalline diamonds with the size restricted only by the availability of one large initial diamond substrate. The initial substrate is expensive but can be used repetitively to produce a large number of single-crystalline CVD diamond films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110531
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of fluoridated milk on caries in primary teeth: 21-month results (2003)
    Oxford, UK : Munksgaard International Publishers
    Community dentistry and oral epidemiology 31 (2003), S. 0 
    Details
    ISSN: 1600-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract  Objectives: Use of fluoridated milk has been shown to be a safe and effective method to prevent caries in permanent teeth in children. However, studies on its effectiveness on caries prevention in the primary teeth are scarce. The purpose of the present study was to evaluate the effect of milk fluoridation on caries development in young Chinese children.Methods: This was a community-based demonstration study carried out in Beijing, China. All children in three selected kindergartens were invited to participate. Each participant consumed 200 ml of fluoridated milk (concentration 2.5 mg F− per litre) per day from Monday to Friday in the kindergarten, and was given two packs of fluoridated milk (250 ml) for consumption at home on Saturday and Sunday every week. Children from a similar background, but without access to fluoridated milk, attending two other kindergartens, were used as the control.Results: There were 534 children (mean age 54 ± 4 months) and 305 children (mean age 53 ± 4 months) in the test and control groups, respectively, at baseline. After 21 months, 417 and 247 children in the test and control groups, respectively, remained in the study. There was no statistically significant difference in the baseline mean dmft scores between the two groups (3.2 vs. 3.5, P = 0.312). After 21 months, the mean net caries increment was 0.4 dmft for the test group and 1.3 dmft for the control group (t-test, P 〈 0.001).Conclusion: The consumption of fluoridated milk by the kindergarten children in Beijing was an effective measure in preventing caries in the primary teeth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-0528.2003.00048.x
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