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  • Springer  (139)
  • Wiley  (12)
  • 1995-1999  (132)
  • 1975-1979  (19)
  • 1
    Electronic Resource
    Electronic Resource
    Synthesis and properties of poly(ethylene glycol) macromer/β-chitosan hydrogels (1997)
    Springer
    Journal of materials science 8 (1997), S. 537-541 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Semi-interpenetrating polymer network (semi-IPN) hydrogels composed of β-chitosan and poly(ethylene glycol) diacrylate macromer (PEGM) were synthesized and characterized for the application as potential biomedical materials. The mixture of PEGM and β-chitosan, dissolved in water including a small amount of acetic acid, was cast to prepare hydrogel films, followed by a subsequent crosslinking with 2,2-dimethoxy-2-phenylacetophenone as a non-toxic photoinitiator by ultraviolet irradiation. Photocrosslinked hydrogels exhibited relatively high equilibrium water content in the range 77–83% which is mainly attributed to the free water content rather than to the bound water, hydrogen bonded with components in semi-IPN hydrogels. The crystallinity, thermal properties and mechanical properties of semi-IPN hydrogels were studied. All the photocrosslinked hydrogels revealed a remarkable decrease in crystallinity. The glass transition temperatures, Tg, of crosslinked PEGM segment in semi-IPNs increased compared with poly(ethylene glycol) itself. However, with increasing β-chitosan content their Tg decreased owing to the higher degree of crosslinking. The tensile strengths of semi-IPNs in dry state were rather high, but those of hydrogels in wet state decreased drastically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018594614087
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  • 2
    Electronic Resource
    Electronic Resource
    Preparation of CuInSe2 thin films by selenization of co-sputtered Cu–In precursors (1998)
    Springer
    Journal of materials science 9 (1998), S. 361-366 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract CuInSe2 thin films have been prepared by high Se vapor selenization of co-sputtered Cu–In alloy precursors within a partially closed graphite container. Cu–In alloys with different compositions were investigated. X-ray diffraction (XRD) analysis of the films showed mainly CuIn2 and Cu11In9 phases and the Cu11In9 peak intensity was found to increase as the alloy composition tended towards Cu-rich. A linear dependence of the alloy composition on the Cu/In deposition power was observed from energy dispersive analysis by X-rays (EDX). A three-fold volume expansion was exhibited by all the CuInSe2 films after selenization at 500–550 °C. Scanning electron microscopy (SEM) analysis of the films showed large and densely packed crystal structures with sizes above 5 μm. The CuInSe2 films exhibited single phase chalcopyrite structure with preferential orientation in the (1 1 2) direction. The EDX composition analyses of the films showed Cu/In ratio ranging from 0.43 to 1.2, and Se/(Cu+In) ratios from 0.92 to 1.47. The measured film resistivities varied from 10-1 to 105 Ωcm. The Cu–In alloy precursors with Cu/In ratio less than 0.70 were found to form CuIn3Se5 a defect chalcopyrite compound. All films were Se rich, with the exception of samples with very high Cu content.© 1998 Kluwer Academic Publishers
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008936210166
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  • 3
    Electronic Resource
    Electronic Resource
    The Brevibacterium albidum gene encoding the arginine tRNACCG complements the growth defect of an Escherichia coli strain carrying a thermosensitive mutation in the rnpA gene at the nonpermissive temperature (1997)
    Springer
    Molecular genetics and genomics 254 (1997), S. 464-468 
    Details
    ISSN: 1617-4623
    Keywords: Key words Brevibacterium albidum  ;  Arginine tRNACCG  ;  Escherichia colirnpA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Escherichia colirnpA gene encodes C5 protein, the protein component of RNase P. The rnpA49 mutation renders the C5 protein thermosensitive, which results in thermosensitivity of RNase P function. The chromosomal DNA region from Brevibacterium albidum that complements the rnpA49 mutation was analysed. The gene capable of complementing the growth defect of an rnpA49 mutant strain at nonpermissive temperature was identified as the gene for an arginine tRNA with anticodon CCG by a deletion analysis combined with complementation assays. Transcription of the arginine tRNA gene carried on a multicopy plasmid was correlated with the complementation of the rnpA49 mutation, indicating that the gene product is indeed responsible for complementation of the rnpA49 mutation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004380050440
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  • 4
    Electronic Resource
    Electronic Resource
    Exact Algorithm for the Surrogate Dual of an Integer Programming Problem: Subgradient Method Approach (1998)
    Springer
    Journal of optimization theory and applications 96 (1998), S. 363-375 
    Details
    ISSN: 1573-2878
    Keywords: Integer programming ; surrogate dual ; nondifferentiable optimization ; subgradient method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract One of the critical issues in the effective use of surrogate relaxation for an integer programming problem is how to solve the surrogate dual within a reasonable amount of computational time. In this paper, we present an exact and efficient algorithm for solving the surrogate dual of an integer programming problem. Our algorithm follows the approach which Sarin et al. (Ref. 8) introduced in their surrogate dual multiplier search algorithms. The algorithms of Sarin et al. adopt an ad-hoc stopping rule in solving subproblems and cannot guarantee the optimality of the solutions obtained. Our work shows that this heuristic nature can actually be eliminated. Convergence proof for our algorithm is provided. Computational results show the practical applicability of our algorithm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022622231801
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  • 5
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    Exact Algorithm for the Surrogate Dual of an Integer Programming Problem: Subgradient Method Approach (1998)
    Springer
    Details
    Publication Date: 1998-02-01
    Print ISSN: 0022-3239
    Electronic ISSN: 1573-2878
    Topics: Mathematics
    Published by Springer
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    PAPER CURRENT
  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and properties of poly(dipropargyl-16-crown-5) (1996)
    Springer
    Polymer bulletin 36 (1996), S. 391-398 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary We have synthesized a polyacetylene derivative, poly(dipropargyl-16-crown-5), through the cyclopolymerization of the corresponding monomer by metathesis catalysts. The polymer containing crown-ether units was characterized by spectroscopic and thermal techniques. The polymer structure is believed to be a cyclized from with both five- and sixmembered rings. The polymer exhibits high cation-binding properties and ionochromic effects. The order of the selectivity of alkali- metal cations for both the monomer and the polymer was found to be Na+〉K+〉Li+ and the polymer shows the largest red shift by approximately 40 nm in λmax for Na+.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315054
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  • 7
    Electronic Resource
    Electronic Resource
    Dependence of propagation loss on etching depth in Al0.3Ga0.7As/GaAs/Al0.3Ga0.7As strip-loaded type waveguides (1995)
    Springer
    Optical and quantum electronics 27 (1995), S. 363-369 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Al0.3Ga0.7As/GaAs/Al0.3Ga0.7As strip-loaded waveguides were fabricated using a broad-beam electron cyclotron resonance (ECR) ion source. It was found that a very smooth etching profile can be obtained by ECR ion etching and the etching rate of Al0.3Ga0.7As is 70 nm min-1. The propagation losses of strip-loaded type III–V compound semiconductor waveguides with various etching depths were studied by the Fabry-Perot cavity method. It was observed that the reflectance at the cleavage increases slightly with etching depth for TE polarization. The propagation loss is measured as 1.5 dB cm-1 for etching depth of 0.7 μm, less than 1 dB cm-1 for 0.8 μm, and 3.5 dB cm-1 for 1.1 μm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00563571
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  • 8
    Electronic Resource
    Electronic Resource
    Polarimetric fibre laser sensors using Er-doped fibre (1995)
    Springer
    Optical and quantum electronics 27 (1995), S. 481-485 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A polarimetric fibre laser sensor with narrow polarization mode beat frequency bandwidth is demonstrated using a polarization-maintaining Er-doped fibre. The slope coefficients of 124kHz°C-1 cm-1 and 137kHz μm-1 are obtained for temperature change and longitudinal strain measurements, respectively. A new configuration of polarimetric fibre laser sensor is also demonstrated using a conventional Er-doped fibre as a gain medium and a short length of polarization-maintaining fibre as a sensing part.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00563587
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  • 9
    Electronic Resource
    Electronic Resource
    Large area InAlAs/InGaAs metal semiconductor metal photodiode with very low dark current and its frequency response (1997)
    Springer
    Optical and quantum electronics 29 (1997), S. 953-959 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract An MBE grown InGaAs metal semiconductor metal (MSM) photodiode (PD) with an InAlAs barrier enhancement layer is reported that has very low dark current and high speed characteristics. The detector using Cr/Au Schottky metal fingers with 4m spacing on a large active area of 300×300m2 shows a low dark current of 38nA at 10V. This corresponds to a dark current density of 0.42pA/m2 and is, to our knowledge, the best dark current ever obtained from a large area InGaAs MSM PD. The device also shows a low capacitance of 0.8pF and a high 3dB bandwidth of 2.4GHz. By fitting the measured frequency response to a model consisting of both RC time and transit time limited responses, we show that the device has an RC time and a transit time limited 3dB bandwidth of 3.0 and 4.9GHz, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018589903010
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  • 10
    Electronic Resource
    Electronic Resource
    HR-coated facet effect on the spectral characteristics of a three-section DBR tunable laser (1995)
    Springer
    Optical and quantum electronics 27 (1995), S. 473-479 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract High-relfection (HR)-coated facet effects on the spectral characteristics of a three-section distributed Bragg reflector (DBR) tunable laser are investigated theoretically, in which the output power emits to the DBR section. It is found that the output power to the DBR sectionP DBR compared to the cleaved facet output powerP 0 is nearly constant to some degree with increasing tuning current. Owing to the high-Q resonator, the HR-coated DBR laser showed a decrease in spectral linewidth. However, there is still linewidth broadening of the HR-coated DBR laser even though the rate of increase is smaller than that of the cleaved-facet DBR laser. In the case of output power emission to the DBR section, it is thought that the HR-coated effect can overcome the decrease in output power under frequency tuning, which is one of the most important drawbacks of DBR laser performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00563586
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