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  • Springer  (115)
  • 2020-2022
  • 1995-1999  (115)
  • 1960-1964
  • 1935-1939
  • 1920-1924
  • 1999  (62)
  • 1996  (53)
  • 1
    Electronic Resource
    Electronic Resource
    Structural study of fucoidan from Cladosiphon okamuranus tokida (1999)
    Springer
    Glycoconjugate journal 16 (1999), S. 19-26 
    Details
    ISSN: 1573-4986
    Keywords: fucoidan ; sulfated fucan ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A structural study was carried out on a fucoidan isolated from the brown seaweed Cladosiphon okamuranus. The polysaccharide contained fucose, glucuronic acid and sulfate in a molar ratio of about 6.1 : 1.0 : 2.9. The results of Smith degradation showed that this polysaccharide has a linear backbone of 1→3-linked α-fucopyranose with a half sulfate substitution at the 4-positions, and a portion of the fucose residues was O-acetylated. The data obtained from partial acid hydrolysis, a methylation analysis and NMR spectra indicated that the α-glucuronic acid residue is linked to the 2-positions of the fucose residues, which were not substituted by a sulfate group. These results indicated that the average structure of this fucoidan is as follows: -[(→3Fuc-4(±OSO3-)α1−)5→3[GlcAα1→2]Fucα1−]n−. (Half of each fucose residue was sulfated. One O-acetyl ester was present in every 6 fucose residues.)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006945618657
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis of polymers bearing azo-dye chromophore with photocrosslinkable moiety for nonlinear optics (1996)
    Springer
    Polymer bulletin 36 (1996), S. 407-414 
    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 Novel photocrosslinkable second-order nonlinear optical(NLO) polymers were synthesized from radical homopolymerization of 4-[N-ethyl-N-(2-methacryloyloxyethyl)]amino-4′-(2-cinnamoyloxyethyloxycarbonyl)-2′-nitroazobenzene(MACN) or copolymerization of MACN with 2-(cinnamoxyloxy)ethyl methacrylate(CM), and from polycondensation of 4-[N,N-bis(2-hydroxyethyl)]amino-4′-(2-cinnamoyloxyethyloxycarbonyl)-2′-nitroazobenzene(HACN) with p-phenylenediacyloyl chloride(PD). For the purpose of obtaining an optimized condition of UV irradiation for poling treatment involving photocrosslinking, photoreactivity of these NLO polymer films was investigated. There was observed considerably different photoreaction behavior, especially in photofading of the NLO chromophore, between MACN polymer and HACNPD polycondensate; the latter faded more rapidly than the former. A reason for this phenomenon was considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315056
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  • 3
    Electronic Resource
    Electronic Resource
    High output power operation of 1.3-μm strained MQW lasers with low threshold currents at high temperature (1996)
    Springer
    Optical and quantum electronics 28 (1996), S. 503-511 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We have investigated the temperature dependencies of the slope efficiency and the threshold current for strained multiquantum well (MQW) lasers as a parameter of the well number. Smaller well numbers mean larger temperature dependencies of the slope efficiency and the threshold current, while larger well numbers mean larger internal loss and broadening of the photoluminescence linewidth of the MQW structure. Furthermore, the change in the slope efficiency with temperature change is related to the change in internal loss. In this work, the 1.3-μm strained MQW laser with a compressive strain of 1.0% and 7 wells shows the highest output power of 6.8 mW for an injection current of 50 mA and the lowest threshold current of 5.5 mA at 85°C, and the lowest variation in output power of 2.0 dB from 25–85°C at injection current of 50 mA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00943618
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  • 4
    Electronic Resource
    Electronic Resource
    Blue Luminescence from Silicon Nanoparticles Suspended in Organic Liquids (1999)
    Springer
    Journal of cluster science 10 (1999), S. 359-380 
    Details
    ISSN: 1572-8862
    Keywords: Silicon ; nanoparticles ; luminescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We have prepared several nanometer-sized silicon colloids in organic liquids in the range from 3.7 to 9.8 nm with a constant weight density of 1 mg/ml by a gas evaporation technique. The blue–green luminescent energy was found to be independent of size, in contrast to its intensity and optical absorption, which showed a clear size effect. Special emphasis is placed on the advantage of using a colloidal system: controllability of mass density in a unit volume, isolation of each particle, selection of wide band-gap substances, capability of absolute quantum efficiency, and easy surface modification. As an example of the above advantages, we have determined the absolute quantum yield as a function of size. From the quantum yield thus derived and the proposed model that combines surface as well as volume effects, experimentally obtained parameters such as the diffusion velocity of an electron–hole pair and the initial flight distance of this pair are found to be consistent with those obtained from other data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021981714227
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  • 5
    Electronic Resource
    Electronic Resource
    Cu/Ni colloidal dispersions stabilised by calcium and barium stearates for the amination of oxo-alcohols (1996)
    Springer
    Catalysis letters 40 (1996), S. 123-130 
    Details
    ISSN: 1572-879X
    Keywords: Cu/Ni colloidal dispersion ; barium stearate ; calcium stearate ; protective colloid ; amination of oxo-alcohols ; tertiary amine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Bimetallic Cu/Ni colloidal dispersions (the core catalyst) stabilised by a combination of calcium and barium stearates as protective colloids (catalyst C) showed a remarkable catalytic activity-several times higher than that of the core catalyst stabilised by barium stearate only (catalyst A) for the amination reaction of low reactive oxo-alcohols, having steric hindrance by branched alkyls, with dimethylamine to prepare N,N-dimethyl tertiary amines. Application of the catalyst C for the same amination reaction of dodecyl alcohol could be performed at a lower catalyst concentration of even 100 ppm based on copper at 220° C with a tertiary amine yield of 92% in a three hours' reaction. The reaction mixture containing catalyst C formed a gel at room temperature and formed a stable homogeneous solution with acetone as a polar solvent. It is postulated that water-repellency of calcium stearate and further incorporation of barium stearate as a second promoter yields a doubly stabilised structure for the core catalyst resulting in a remarkable increase in catalytic activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807469
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  • 6
    Electronic Resource
    Electronic Resource
    Asymptotic estimation for the condition numbers in BEM (1996)
    Springer
    Numerische Mathematik 73 (1996), S. 209-233 
    Details
    ISSN: 0945-3245
    Keywords: Mathematics Subject Classification (1991): 65R20, 65N38, 65N35, 65R30, 65N12
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary. We apply the boundary element methods (BEM) to the interior Dirichlet problem of the two dimensional Laplace equation, and its discretization is carried out with the collocation method using piecewise linear elements. In this paper, some precise asymptotic estimations for the discretization matrix $L_n$ (where $n$ denotes the division number) are investigated. We show that the maximum norm of $L^{-1}_n$ and the condition number of $L_n$ have the forms: $C_0 n + O (1)$ and $C_1 n +o (n)$ , respectively, as $n \to \infty$ , where the constants $C_0$ and $C_1$ are explicitly given in the proof. Although these estimates indicate illconditionedness of this numerical computation, the $O(n^{-2})$ -convergence of this scheme with maximum norm is proved as an application of the main results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002110050191
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  • 7
    Electronic Resource
    Electronic Resource
    Vector model analysis in nondestructive imaging by using the photothermal deflection methods (1999)
    Springer
    Applied physics 69 (1999), S. 343-346 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 78.20.Hp; 42.30.Va; 65.90.+i
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. The noncontact imaging of the buried structures is carried out in the open-air atmosphere by using the photothermal deflection (PTD) method. We applied these techniques to the layered samples. Besides the PTD images for the optically opaque buried structures, the parameters of the materials such as thermal diffusivity can also be calculated from the PTD amplitude and phase signal in the PTD scanning images. When the PTD signals at two different modulation frequencies are used, the thermal diffusivity of the buried structure can be obtained from the PTD signal outside of the sample nondestructively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003390051011
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  • 8
    Electronic Resource
    Electronic Resource
    Tissue Distribution of Methylsulfonyl Metabolites Derived from 2,2′,4,5,5′-Penta- and 2,2′,3,4′,5′,6-Hexachlorobiphenyls in Rats (1999)
    Springer
    Archives of environmental contamination and toxicology 37 (1999), S. 135-142 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. The time courses of fecal excretion and tissue distribution of metabolites derived from 2,2′,4,5,5′-pentachlorobiphenyl (CB101) and 2,2′,3,4′,5′,6-hexachlorobiphenyl (CB149) were investigated in male Wistar rats. The metabolism of both congeners involved primarily hydroxylation at the 3-position, and methylthiolation at the 4-position. Metabolites distributed in tissue were dominated by different ratios of 3- and 4-methylsulfonyl (MeSO2) metabolites. The 3-/4-MeSO2 metabolite ratios in liver and adipose tissue for both congeners were 0.41–0.61 at day 4, and then increased to 0.85–1.00 for up to day 42. In contrast, the ratios in lung were 0.03–0.04, and then decreased to 0.01. Compared to the unchanged PCBs at day 42, the distribution ratios of 3-MeSO2 metabolites were greater in the order of liver (0.46 for CB101 and 0.21 for CB149) 〉 kidney 〉 blood 〉 lung 〉 adipose tissue, whereas those of 4-MeSO2 metabolites were in the order of lung (9.50 for CB101 and 4.00 for CB149) 〉 kidney 〉 blood 〉 liver 〉 adipose tissue, indicating the different binding affinity of 3-MeSO2 metabolites in liver from that of 4-MeSO2 metabolites in lungs of rats. Furthermore, the structure-tissue affinity relationship for 3-MeSO2 metabolites was investigated, following the administration of 11 3-MeSO2-PCB congeners to rats. The results indicated that the retention potential of 3-MeSO2 metabolites in the liver largely depends on the ortho-chlorine substitution in the biphenyl ring rather than the degree of chlorination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002449900498
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  • 9
    Electronic Resource
    Electronic Resource
    K 2 of a Fermat quotient and the value of its L-function (1996)
    Springer
    K-Theory 10 (1996), S. 73-82 
    Details
    ISSN: 1573-0514
    Keywords: regulator ; special value of Hasse-Weil L-function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Two linearly independent elements of k 2 of a certain quotient of a Fermat curve is exhibited in an explicit manner. The covolume of the regulator and the value of the L-function of the curve is numerically computed, and their ratio is nearly equal to a simple rational number.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00534889
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  • 10
    Electronic Resource
    Electronic Resource
    Molecular analysis of the gene cluster involved in cephalosporin biosynthesis from Lysobacter lactamgenus YK90 (1996)
    Springer
    Applied microbiology and biotechnology 44 (1996), S. 589-596 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Determination of the nucleotide sequence downstream from the Lysobacter lactamgenus pcbC gene encoding isopenicillin N synthase revealed that five open-reading frames (ORF) including the pcbC gene were tightly linked in the same orientation. Each ORF has the remarkable feature of the protein-coding frame in the DNA sequence with a high G + C content. Expression in Escherichia coli and a comparison of the deduced amino acid sequences with published sequences showed that the gene cluster contained a deacetoxycephalosporin C synthetase (DAOCS) gene (cefE), an ORF having homology with the Cephalosporium acremonium DAOCS/deacetylcephalosporin C synthetase gene (cefEF), an isopenicillin N epimerase gene(cefD), and a β-lactamase gene. The gene order was pcbC-cefE-ORF3-cefD-β-lactamase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00172490
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