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  • Polymer and Materials Science  (6)
  • PACS. 03.65.-w Quantum mechanics – 71.23.An Theories and models; localized states – 73.21.Hb Quantum wires  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Simple model for a quantum wire II. Statistically correlated disorder (2003)
    Springer
    The European physical journal 32 (2003), S. 537-543 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 03.65.-w Quantum mechanics – 71.23.An Theories and models; localized states – 73.21.Hb Quantum wires
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: In a previous paper (Eur. Phys. J. B 30, 239-251 (2002)) we have presented the main features and properties of a simple model which -in spite of its simplicity- describes quite accurately the qualitative behaviour of a quantum wire. The model was composed of N distinct deltas each one carrying a different coupling. We were able to diagonalize the Hamiltonian in the periodic case and yield a complete and analytic description of the subsequent band structure. Furthermore the random case was also analyzed and we were able to describe Anderson localization and fractal structure of the conductance. In the present paper we go one step further and show how to introduce correlations among the sites of the wire. The presence of a correlated disorder manifests itself by altering the distribution of states and the localization of the electrons within the system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2003-00132-5
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  • 2
    Electronic Resource
    Electronic Resource
    Infinite chain of different deltas: A simple model for a quantum wire (2002)
    Springer
    The European physical journal 30 (2002), S. 239-251 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 03.65.-w Quantum mechanics – 71.23.An Theories and models; localized states – 73.21.Hb Quantum wires
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: We present the exact diagonalization of the Schrödinger operator corresponding to a periodic potential with N deltas of different couplings, for arbitrary N. This basic structure can repeat itself an infinite number of times. Calculations of band structure can be performed with a high degree of accuracy for an infinite chain and of the correspondent eigenlevels in the case of a random chain. The main physical motivation is to modelate quantum wire band structure and the calculation of the associated density of states. These quantities show the fundamental properties we expect for periodic structures although for low energy the band gaps follow unpredictable patterns. In the case of random chains we find Anderson localization; we analize also the role of the eigenstates in the localization patterns and find clear signals of fractality in the conductance. In spite of the simplicity of the model many of the salient features expected in a quantum wire are well reproduced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2002-00377-4
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  • 3
    Electronic Resource
    Electronic Resource
    Study by means of computerized spectroscopy of copolymerization grafting (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 459-465 
    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: Experiments were performed in an attempt to explain the probable mechanism present in the polymeric grafting process and to determine the percentual ratio between N-4-[4-(dietylamine) fenil] fenilmetilene-2-5-cyclohexadiene-1-ilidene-N-etil ammonium monomer and the sulfate (1 : 1) (Green Vinyl Malachite: GVM) in poly-N-vinylcarbazole/Green Vinyl Malachite, PNVC/GVM, specimens of the copolymerization product. Computerized spectroscopic techniques, optimized for maximum absorption and minimum effect noise, were utilized to subtract the spectral information of the GVM monomer noncopolymerized species from the macromolecular base with no special sampling techniques. The samples were processed using the standard PECDS software with the infrared Data Station. The copolymerization process resulted in a 52.91% concentration of a noncopolymerized fraction consisting of dimerized structures of the reactant monomer.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460311
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  • 4
    Electronic Resource
    Electronic Resource
    Applications of computer difference spectroscopy in ion-exchange resins analysis (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 55 (1995), S. 675-678 
    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: Infrared spectra demonstrate the use of computer difference spectroscopy and other dataprocessing routines to derive and enhance the difference spectra that relates the concentration of a resin to the concentration of other resins in the mixture. Therefore, a simple quantitative treatment accounting for the resin concentration has been determined. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070550503
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  • 5
    Electronic Resource
    Electronic Resource
    Deformation behavior of low-carbon Co-Cr-Mo alloys for low-friction implant applications (1996)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 31 (1996), S. 409-419 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The plastic flow behavior of wrought Co-27Cr-5Mo-0.05C alloy was investigated at 298 K as a function of grain size using uniaxial tension testing. The microstructures produced by deformation were characterized using X-ray diffraction, reflected light, and scanning electron microscopy. This study revealed that material with initially coarse face-centered cubic (fcc) grains exhibits larger uniform ductility than material with fine grain size. Typically, increasing the grain size from 7 to 70 μm reduces the yield strength by about 50% and increases the elongation to fracture from 12 to 30% with a small effect on the tensile strength. The material is capable of deforming uniformly to large strains without developing plastic instabilities until the point of fracture. This effect was found to be associated with the occurrence of transformation-induced plasticity (TRIP) in the coarse-grained material. TRIP enhances the material's ability to deform uniformly by maintaining a high rate of strain hardening during deformation. Smaller fcc initial grain size inhibits the transformation kinetics of the fcc-hexagonal close-packed phase transition according to the Olson-Cohen model. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Effect of compressive straining on corrosion resistance of a shape memory(Ni-Ti alloy in ringer's solution (1996)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 32 (1996), S. 583-591 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effect of various degrees of deformation was investigated at specific locations in the stress-strain curve under compression on the corrosion resistance of a wrought Ni-Ti alloy with a martensite to austenite transformation peak of 110°C. Two metallurgical conditions were evaluated: 30% cold drawn and annealed at 900°C for 1 h. The cold drawn material was tested for corrosion resistance after 5.8, 7.4, 12.2, and 24.5% applied strain. Similarly, the corrosion resistance of the annealed material condition was examined after deformation in compression to 11.9, 22.3, and 24.4% strain. Tafel extrapolation and cyclic polarization tests were used for corrosion characterization of each alloy condition. It was found that the corrosion current density undergoes a significant reduction while the breakdown potential improves at increasing strains. In particular, the alloy in the annealed condition exhibited breakdown potentials above 1000 mV with current densities lower than 10 μA cm-2 when it was strained to 24.4%. © 1996 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of carbon content on the resistance to localized corrosion of as-cast cobalt-based alloys in an aqueous chloride solution (1995)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 29 (1995), S. 441-453 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effect of carbon content on the resistance to localized corrosion of ASTM-F75, as-cast cobalt-based alloys, was studied using potentiostatic polarization tests in Ringer's solution. Critical pitting potentials were estimated from the potentiostatic polarization curves and were found to increase with decreasing carbon content. The highest resistance to pitting corrosion observed at low C contents was attributed to a greater chemical and microstructural homogeneity in the as-cast condition. The results of the investigation led to the conclusion that the use of low C content ASTM-F75 as-cast alloys in the manufacture of orthopedic implants may result in a lower release rate of corrosion products which should improve the “in vivo” performance of the implants. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820290404
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  • 8
    Electronic Resource
    Electronic Resource
    Inhomogeneous charge effect on a natural mineral studied by XPS (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 21 (1994), S. 659-664 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We report on XPS results that show an inhomogeneous charge effect, greater than 1.0 eV and far greater than the accuracy of the measurements (∼0.2 eV), exhibited by a natural mineral essentially composed of SiO2 and Fe2O3. This mineral has proved to be an efficient catalyst in a Fischer-Tropsch reaction. We have corrected this differential charge effect by using two internal references in order to interpret satisfactorily our XPS data.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740210910
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