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  • 1
    Electronic Resource
    Electronic Resource
    van der Waals epitaxial growth of thin BiI3 films on PbI2 and CdI2 substrates by a hot wall method (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 2735-2738 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A hot wall technique was applied to grow very thin BiI3 single crystals about 100–1000 A(ring) thick by the achievement of low-temperature growth. The so-called van der Waals epitaxy became possible by employing layered materials such as PbI2 and CdI2 as substrate. BiI3 thin films grown with optimized conditions exhibited a sharp band-edge direct exciton absorption line of 30-meV half-width, which is much sharper than that of a single crystal grown by a conventional method reported so far. The transmission electron diffraction measurements were carried out on the films. It was revealed that highly perfect single crystals with a 4-mm diameter size were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346449
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  • 2
    Electronic Resource
    Electronic Resource
    Superconductivity and crystallinity of Ba2Y1Cu3O7−δ thin films prepared by pulsed laser deposition with substrate bias voltage (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 6331-6335 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Substrate bias voltages were found to be significantly effective in preparing high-quality laser-deposited superconducting Ba2Y1Cu3O7−δ films at reduced substrate temperatures. The zero-resistance temperature of the biased films, positive bias being more effective than negative, decreased very slightly when the substrate temperature was lowered, whereas that of the unbiased films decreased considerably. In addition, the surface morphology and c-axis orientation have been improved by applying substrate bias voltages. Bias voltages within ±500 V hardly affect the composition of the resulting films so that stoichiometric films have been obtained from a stoichiometric target. A time-resolved optical observation revealed that a short time emission, probably being oxygen plasma, occurred in a few μs after the laser pulse impingement. The improvement in crystallinity of the resulting films is attributed to this emission. The velocity of emissive species in the plume was determined to be 6×105 cm/s. Under positive-biased conditions slower components with a velocity of 3×105 cm/s or less were also observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346877
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  • 3
    Electronic Resource
    Electronic Resource
    Origins of charged particles in vapor generated by electron-beam evaporation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 4548-4555 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The origins of electrons and ions in uranium vapor generated by electron-beam evaporation have been determined. Measurements were made for the electron emission current due to high-energy electron-beam irradiation on a uranium surface (backscattered electrons, etc.), thermionic emission current from the melt surface, and electron current due to vapor ionization. Comparison of these currents confirmed that vapor ionization was the main electron generation process at evaporation surface temperatures above 2200 K. The ionized vapor formed a weakly ionized plasma of very low electron temperature: The degree of ionization ≤1%, electron temperature ≤0.3 eV. The electron-impact ionization process contributed mainly to plasma formation. Beam electrons, their backscattered electrons, and secondary electrons from the beam-irradiated uranium surface were the source electrons for this process. Thermal ionization was the next major process. In addition to the plasma formation model, plasma behavior in vapor was described by a one-dimensional symmetric expansion model. The calculated degree of ionization was in good agreement with the measured value over a wide range of evaporation temperatures and electron-beam currents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352334
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  • 4
    Electronic Resource
    Electronic Resource
    Orientational correlation in liquid phosphorous tribromide studied by pulsed neutron total scattering (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 5486-5490 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Structure factor Sm(Q) of liquid phosphorous tribromide (PBr3) has been measured at room temperature by means of pulsed neutron total scattering technique. Characteristic features of the experimental Sm(Q) are analyzed in terms of preferred orientations introduced between the nearest neighbors as well as a packing of effectively uncorrelated molecules. The preferred orientation estimated in this analysis is such that a top (or a P atom) of pyramidal shape of each PBr3 molecule points in nearly the same direction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458527
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  • 5
    Electronic Resource
    Electronic Resource
    Sequential deposition growth of Bi-Sr-Ca-Cu-O systems observed using in situ reflection high-energy electron diffraction (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 654-655 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The crystal growth mechanism in Bi-Sr-Ca-Cu-O thin films has been revealed by sequential deposition with an electron cyclotron resonance (ECR) oxygen plasma using in situ reflection high-energy electron diffraction (RHEED) observation. A series of RHEED patterns presents clear evidence that the unit cell of the Bi-Sr-Ca-Cu-O structure is completed as the Bi layers have sandwiched Sr, Ca, and Cu layers. This crystalline process is not an atomic layer by atomic layer growth but a "unit cell by unit cell'' growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104559
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  • 6
    Electronic Resource
    Electronic Resource
    Epitaxial growth of diamond thin films on cubic boron nitride {111} surfaces by dc plasma chemical vapor deposition (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 563-565 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diamond thin films have been grown epitaxially on high-pressure synthesized cubic boron nitride (c-BN) particles by using dc plasma chemical vapor deposition. At the early growth stage of the film on c-BN{111} surfaces, the island structure is observed and the number density of islands is about 1011 cm−2. The growth and the coalescence of islands are also found by scanning electron microscopy observation. The continuous film is obtained at the thickness of about 2000 A(ring) and the surface of the film is rather smooth. The Raman peak of the epitaxial diamond film shows the shift toward the lower wave number due to the tensile stress involved in the film.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103647
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  • 7
    Electronic Resource
    Electronic Resource
    An extreme ultraviolet radiation source for the simulation of the ionosphere (1991)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 1721-1726 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An extreme ultraviolet (EUV) radiation source for space simulation of plasma and other related phenomena in the laboratory has been developed. A total of forty-eight small EUV lamps are put together to give a radiation diameter of more than 30 cm. The intensity of this lamp at the hydrogen Lyman-alpha line is more than twenty five times stronger than sunlight at the same wavelength and at a distance of about 30 cm from the source. The source is capable of emitting EUV radiations from 110 nm to the longer wavelengths, either continuously or in pulses, and has been used to produce a plasma of 105 els/cm3 when the pressure of NO gas in the chamber was 10−4 Torr. Since this plasma is extremely calm and fairly Maxwellian, it can be used to study the electron collection mechanism of a probe in a collision dominant medium. The source was also utilized to study the interaction between vibrationally excited nitrogen molecules and thermal electrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142412
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  • 8
    Electronic Resource
    Electronic Resource
    Formation of amorphous aluminum tantalum nitride powders by mechanical alloying (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 1562-1563 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Aluminum tantalum nitride amorphous alloy powders have been synthesized by a high energy ball mill under purified nitrogen gas (N2) flow at room temperature. The alloy powders were characterized by means of transmission electron microscopy, differential thermal analysis, and chemical analysis. An amorphous phase containing 18 at. % N2 was obtained after 65 ks of the milling time. At the final stage of milling (72 ks) the crystallization temperature, Tx, and enthalpy change of crystallization, ΔHx, are 1115 K and −95 kJ mol−1, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107251
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  • 9
    Electronic Resource
    Electronic Resource
    Phorbol Myristate Acetate Corrects Impaired NK Function of Old Mice (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 34 (1991), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Previous studies indicated that natural killer (NK) activity in mice declined with age. In this report, we investigated the basis for the decreased activity of NK cells in older mice. Our results demonstrated that phorbol myristate acetate(PMA)–an activator of protein kinase C(PKC)– corrects the impaired NK function of older animals. The per cent increase of NK activity post treatment with PMA is 226 261 % at effector: target (E:T) ratio= 100:1 compared with control untreated cells. The effect of PMA was shown lo be dose dependent. A maximum increase in NK activity was achieved at approximately 10–15 nm PMA. Treatment with PMA does not result in increased binding of NK cells to YAC-1 targets as demonstrated by single-cell assay, in addition, treatment of young NK cells with l-(5–isoquinolinesulphonyl)-2–methylpiperazine dihydrochloride (H-7). a very potent PKC inhibitor, significantly suppressed NK activity (65% of control). Therefore, we conclude that the age-related decline in murine NK activity may reside in the early signalling events leading to triggering of PKC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3083.1991.tb01562.x
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  • 10
    Electronic Resource
    Electronic Resource
    Interleukin-1β stimulates collagenase production by cultured human periodontal ligament fibroblasts (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 29 (1994), S. 0 
    Details
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: To examine the effects of interleukin-lβ (IL-1β) on collagenase production by human periodontal ligament fibroblasts (PLF) and gingival fibroblasts (GF) in Culture, collagenase activity in conditioned media was determined using a novel procedure that circumvented interference by enzyme inhibitors. Fibroblasts obtained from five paired periodontal ligament and gingival tissues were cultured for two weeks, and then incubated for a further 72 h in α-MEM supplemented with various concentrations of IL-1β (0 to 1250 pg/ml). The conditioned media from individual cultures were harvested and treated with dithiothreitol to inactivate TIMPs, and then with APMA, to activate the latent collagenase. Collagenase activity was measured fluorometrically using FITC-collagen as a substrate. IL-lβ induced a ∼2.4 to 5.2-fold increase in collagenase activity in PLF compared to a ∼1.4 to 2.2-fold increase in GF. These results are in contrast to previous studies in which collagenase activity was measured in the presence of TIMPs, and indicate that PLF are more sensitive to IL-1β than GF. Since both PLF and GF are present in periodontal lesions, it is possible that collagenase secretion stimulated by exposure to inflammatory cell products such as IL-lβ may participate in the destruction of collagen fibers involved in periodontal attachment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0765.1994.tb01244.x
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