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  • SOLID-STATE PHYSICS  (17)
  • Electronics and Electrical Engineering  (5)
  • ELECTRONICS AND ELECTRICAL ENGINEERING  (4)
  • Polymer and Materials Science  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Molecular dynamics simulation of a leucine zipper motif predicted for the integrase of human immunodeficiency virus type I (1994)
    New York : Wiley-Blackwell
    Biopolymers 34 (1994), S. 1027-1036 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have used the molecular dynamics (MD) simulation package AMBER4 to search the conformation of a peptide predicted as a leucine zipper motif for the human immunodeficiency virus type I integrase protein (HIV IN-LZM). The peptide is composed of 22 amino acid residues and its location is from Val 151 to Leu 172. The searching procedure also includes two known α-helices that served as positive controls - namely, a 22-residue GCN4-p1 (LZM) and a 20-residue poly(L-alanine) (PLA). A 21-residue peptide extracted from a cytochrome C crystal (CCC-t) with determined conformation as a β-turn is also included as a negative control. At the beginning of the search, two starting conformations - namely, the standard right-handed α-helix and the fully stretched conformations - are generated for each peptide. Structures generated as standard α-helix are equilibrated at room temperature for 90 ps while structures generated as a fully stretched one are equilibrated at 600 K for 120 ps. The CCC-t and PLA helices are nearly destroyed from the beginning of equilibration. However, for both the HIV IN-LZM and the GCN4-p1 LZM structures, there is substantial helicity being retained throughout the entire course of equilibration. Although helix propagation profiles calculated indicate that both peptides possess about the same propensity to form an α-helix, the HIV IN-LZM helix appears to be more stable than the GCN4-p1 one as judged by a variety of analyses on both structures generated during the equilibration course. The fact that predicted HIV IN-LZM can exist as an α-helix is also supported by the results of high temperature equilibration run on the fully stretched structures generated. In this run, the RMS deviations between the backbone atoms of the structures with the lowest potential energy (PE) identified within every 2 ps and the structure with the lowest PE searched in the same course of simulation are calculated. For both the HIV IN-LZM and the GCN4-p1 LZM, these rms values decrease with the decrease of PE, which indicates that both structures are closer in conformations as their PEs are moved deeper into the PE well. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360340806
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Glow discharge polymerization of reactive functional silanes on poly(methyl methacrylate) (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 40 (1990), S. 369-384 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Glow discharge polymerization among such reactive functional silances as 3-methacryloxypropyltrimethoxysilane (MSL), 3-glycidoxypropyltrimethoxysilane (ESL), and vinyltrimethoxysilane (VSL) on poly(methyl methacrylate) was investigated by means of Fourier transform infrared spectroscopy, ESCA analysis, and contact angle measurement. Flow rate of monomer influenced both polymer deposition rate and polymer elemental composition. Infrared spectra showed differences in chemical structure among the polymers prepared from the different silanes. All of the polymers obtained contained similar chemical groups such as —CH3, —CH2—, Si—O—Si, and Si—O—C. Polymers deposited from MSL and ESL contained highly hydrophilic functional groups like C—OH, Si—OH, and C=O on the uppermost layer while that from VSL contained highly hydrophobic functional groups like —CH3 groups. Chemical analysis by ESCA and contact angle measurement gave evidence for the similarity of the polymers prepared from MSL and ESL, in contrast with the differences of the polymers prepared from VSL.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070400306
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  • 3
    Electronic Resource
    Electronic Resource
    Glass peek composite promotes proliferation and osteocalcin production of human osteoblastic cells (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 36 (1997), S. 137-144 
    Details
    ISSN: 0021-9304
    Keywords: PEEK ; composite ; biocompatibility ; cell culture ; osteoblasts ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An isoelastic intramedullary implant has been developed using a composite of polyetheretherketone and 10% random, chopped E-glass fibers (GPEEK). The effect of this novel material on human bone cells has not been defined. The objective of this study was to test whether GPEEK supported the proliferation of the human bone cell line MG63, which exhibits osteoblastlike characteristics. Cells (1 × 105/mL) were propagated on GPEEK discs with three different surface roughnesses (3, 6, and 9 μm) and on polystyrene plates, for comparison. The reaction of MG63 osteoblastlike cells to the GPEEK polymer composite was analyzed by determination of cell yield, osteocalcin production, and levels of alkaline phosphatase. The viable cells that were retrieved from the GPEEK discs of all three surface roughness had an approximate sixfold increase in number. Osteoblastic function of the cells, indicated by osteocalcin production, was unimpaired after a 5-day culture on the three surfaces of GPEEK. The highest level of osteocalcin was produced by osteoblastic cells propagated on GPEEK with a 9-μm surface roughness. The levels of alkaline phosphatase of these cells were similarly greater for the different degrees of surface roughness. Overall, this study demonstrates that GPEEK supported proliferation of osteoblastlike cells and provided a favorable environment for the continued production of osteocalcin in vitro. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res, 36, 137-144, 1997.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of pH on the reactivity ratios in the copolymerization of acrylic acid and acrylamidePresented in part at the Combined Southeast-Southwest Regional Meeting of the American Chemical Society, New Orleans, Louisiana, December 2-4, 1970. (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 2155-2170 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The content of acrylic acid and acrylamide in their copolymers can be controlled by changing pH. The reactivity ratio of acrylic acid decreases with increasing pH, while the reactivity ratio of acrylamide increases with increasing pH. At low pH values, acrylamide is present in its protonated form which causes its reactivity to be low whereas at high pH values the reactivity of acrylic acid is decreased owing to its dissociation. When the monomer and radical approach each other, the acrylate anion becomes the least reactive species because of its symmetrical charge distribution, like charge repulsion and barium ion screening effect. HMO calculations were performed for models of all monomers and polymer radicals involved in copolymerizations. The experimental results concerning the reactivity of acrylic acid and acrylamide in copolymerization and the observed reactivity ratios were discussed on the basis of HMO calculations and resonance and Coulomb electrostatic effects. The observed reactivity ratios were correlated with the calculated differences in resonance energies computed for the models of transition states involved in copolymerizations.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.150090805
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  • 5
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    Fabrication of luminescent porous silicon with stain etches and evidence that luminescence originates in amorphous layers (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Simple immersion of Si in stain etches of HF:HNO3:H2O or NaNO2 in aqueous HF was used to produce films exhibiting luminescence in the visible similar to that of anodically-etched porous Si. All of the luminescent samples consist of amorphous porous Si in at least the near surface region. No evidence was found for small crystalline regions within these amorphous layers.
    Keywords: SOLID-STATE PHYSICS
    Type: ; : Structure of onboa
    Format: text
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  • 6
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    Electronic structure of light-emitting porous Si (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Characterization of light-emitting porous Si films with X-ray photoelectron spectroscopy is reported. Only traces of O are detected on HF-etched samples, in contradiction to an earlier report that oxides are a significant component of porous Si. Si 2p and valence-band measurements demonstrate that the near-surface region of high porosity films which exhibit visible luminescence consists of amorphous Si.
    Keywords: SOLID-STATE PHYSICS
    Type: Applied Physics Letters (ISSN 0003-6951); 60; 1004-100
    Format: text
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  • 7
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    Hydrogen-terminated silicon substrates for low-temperature molecular beam epitaxy (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The preparation of hydrogen-terminated silicon surfaces for use as starting substrates for low-temperature MBE growth is examined in detail. The procedure involves the ex situ removal under nitrogen of residual oxide from a silicon substrate using a spin-clean with HF in ethanol, followed by the in situ low-temperature desorption (150 C) of physisorbed etch residues. The critical steps and the chemical basis for these steps are examined using X-ray photoelectron spectroscopy. Impurity residues at the epilayer-substrate interface following subsequent homoepitaxial growth are studied using AES, SIMS and TEM. Finally, scanning tunneling microscopy is used to examine the effect of cleaning methods on substrate morphology.
    Keywords: SOLID-STATE PHYSICS
    Type: Thin Solid Films (ISSN 0040-6090); 183; 197-212
    Format: text
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  • 8
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    Fabrication of IrSi(3)/p-Si Schottky diodes by a molecular beam epitaxy technique (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: IrSi(3)/p-Si Schottky diodes have been fabricated by a molecular beam epitaxy technique at 630 C. Good surface morphology was observed for IrSi(3) layers grown at temperatures below 680 C, and an increasing tendency to form islands is observed in samples grown at higher temperatures. Good diode current-voltage characteristics were observed and Schottky barrier heights of 0.14-0.18 eV were determined by activation energy analysis and spectral response measurement.
    Keywords: SOLID-STATE PHYSICS
    Type: Applied Physics Letters (ISSN 0003-6951); 56; 2013-201
    Format: text
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  • 9
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    Novel Si(1-x)Ge(x)/Si heterojunction internal photoemission long-wavelength infrared detectors (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The feasibility of a novel p(+)-Si(1-x)Ge(x)-p-Si heterojunction internal photoemission (HIP) IR detector is demonstrated. A degenerately doped p(x)-Si(1-x)Ge(x) layer is required for strong IR absorption to generate photoexcited holes. The Si(1-x)Ge(x) layers are grown by molecular beam epitaxy, with boron concentrations up to 10 to the 20th/cu cm achieved by using an HBO2 source. Photoresponse at wavelengths ranging from 2 to 10 microns has been obtained with quantum efficiencies above 1 percent. The tailorable cutoff wavelength of the HIP detector has been demonstrated by varying the Ge composition ratio in the Si(1-x)Ge(x) layers.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Applied Physics Letters (ISSN 0003-6951); 57; 1422-142
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  • 10
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    Elemental boron-doped p(+)-SiGe layers grown by molecular beam epitaxy for infrared detector applications (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: SiGe/Si heterojunction internal photoemission (HIP) detectors have been fabricated utilizing molecular beam epitaxy of p(+)-SiGe layers on p(-)-Si substrates. Elemental boron from a high-temperature effusion cell was used as the dopant source during MBE growth, and high doping concentrations have been achieved. Strong infrared absorption, mainly by free-carrier absorption, was observed for the degenerately doped SiGe layers. The use of elemental boron as the dopant source allows a low MBE growth temperature, resulting in improved crystalline quality and smooth surface morphology of the Si(0.7)Ge(0.3) layers. Nearly ideal thermionic emission dark current characteristics have been obtained. Photoresponse of the HIP detectors in the long-wavelength infrared regime has been demonstrated.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Applied Physics Letters (ISSN 0003-6951); 60; 380-382
    Format: text
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