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  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The use of stable isotope of carbon, 13C, for the determination of the photosynthetic rate of a marine phytoplankton population was examined. Particular concern was paid to the effects of non-phytoplanktonic organic carbon and the enrichment of inorganic carbon on the estimation of the photosynthetic rate. Photosynthetic rates determined by the 13C method showed a remarkable agreement with those determined by the 14C method. Insitu determinations of photosynthetic rate were made in three different water types: open ocean, coastal and neritic waters, which included oligo- and mesotrophic waters, by using the 13C method established.
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  • 2
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: An expression for the surface energy at the normal-superconducting boundaries of a laminar intermediate state structure is derived as a function of a s /δ, where a s is the width of superconducting domains and δ the surface energy parameter. Numerical calculations show that the ratio δ/ξ (ξ is the coherence length) is almost constant for a s/δ larger than the limit of about 4. This value corresponds to the critical film thickness that separates the regions of type I and type II superconducting behavior.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 276 (1998), S. 388-394 
    ISSN: 1435-1536
    Keywords: Key words Hyaluronic acid ; degradation ; molecular weight ; metal surface ; hydroxyl radical
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  When the viscosity of hyaluronic acid (HA) solution was measured with a rotational visco-meter, depolymerization occurred only by leaving the sample in the cup of the viscometer, while the solution in a glass test tube at the same temperature, 37 °C, was practically stable during the entire period of investigation. As the parts where the sample solution had contact with the viscometer are stainless steel, the participation of metal ions in the depolymerization was suspected. Therefore, experiments were carried out with stainless-steel beads in the HA solution. The results show that the molecular weight of HA decreased on exposure to the beads under aerobic conditions. The addition of 10 beads to 2 ml of a 0.1% HA solution prepared with 0.2 M NaCl reduced the molecular weight to about 75% of the initial value after 4 h. The degradation rate was proportional to the surface area of the beads. However, no dissolution of metal ion was detected, and therefore, this reaction was thought to proceed at the surface of the metal.
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  • 4
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Gm immunoglobulin allotypes have been studied in 1157 individuals of seven Northern Selkup populations, which account for 80% of the entire population of this west Siberian tribe. This study confirms that the northern Selkup populations are a Caucasoid-Mongoloid hybrid. Restriction fragment length polymorphism (RFLP) analysis of the IGHG genes using double BamHI-SacI digests, performed on 475 DNA samples, allowed us to describe nine new BamHI-SacI haplotypes (BS47 to BS55), eight of them being characterized by IGHG gene deletion or duplication: G1 (BS49) or G4 (BS55) deletion, G4 duplication (BS51), GP-G2-G4 multigene deletion (BS50), duplication (BS48, BS53 and BS54) or triplication (BS52). A new rare Gm haplotype 15,16*;1,17;23 has been found associated with BS52. The BS51 haplotype characterized by a duplicated G4 gene (additional 7.85 kb G4 band identifying a new G4*C5 allele) was always found associated with the Gm 5*;3;23 haplotype. A high RFLP diversity has been observed for the Northern-Mongoloid haplotype Gm 15,16*;1,17;.. which was found (1) with the BS27 haplotype characterized by a 3-exon hinge G3 gene, (2) with two different GP-G2-G4 multigene duplications, BS53 and BS54 haplotypes, which differ by the size of the duplicated G4 genes, and (3) with the BS55 haplotype characterized by a G4 deletion. In the Northern Selkups, haplotypes with duplicated genes were observed at a higher frequency (24%) than haplotypes with deleted genes (6%).
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 97 (1995), S. 439-452 
    ISSN: 1434-6036
    Keywords: 61.44.+p ; 71.20.Cf ; 72.15.-v ; 79.60.-i
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements with photoemission spectroscopy in the photon-energy range 35–130 eV have been used to determine the valence band of the stable icosahedral Al65Cu20Os15. Resonant photoemission near the Os 5p → 5d and 4f → 5d transitions has been employed to show that the feature in the valence band with the maximum intensity at 1.5 (1) eV below the Fermi level is predominantly of the Os 5d character. This has been additionally verified by conducting the photoemission measurements in the constant-initial-state mode and by using the effect of the Cooper minimum in the photoionization cross section of the Os 5d orbitals. The valence band feature with the maximum intensity at 3.7 (1) eV below the Fermi level has been shown as being due mainly to the states of the Cu 3d character. The Os 5d and Cu 3d empirical partial density of states have been determined from the photoemission spectra. The decrease of intensity towards the Fermi level has been interpreted as being indicative of the presence of a theoretically predicted pseudogap around the Fermi level. It has been indicated, however, that the Fermi cut-off also contributes to the observed intensity decrease. It has been demonstrated that the energy resolution of the spectroscopic measurements performed so far on quasicrystals was not high enough to unambiguously determine the presence of such a pseudogap. No unusual features in the valence band of icosahedral Al65Cu20Os15, which could be ascribed to its quasiperiodic nature, have been observed within the resolution of the experiment. High energy-resolution spectroscopic measurements were also shown to be essential to observe the theoretically predicted spikiness of the density of states in quasicrystals. A critical review of published spectroscopic data on the electronic structure of quasicrystals has also been presented.
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  • 7
    ISSN: 1435-1536
    Keywords: Chitosan ; molecular weight ; light scattering ; viscosity ; gel permeation chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The viscometric constantsa andK in the Mark-Houwink equation were determined in 0.5 M acetic acid-0.5 M.sodium acetate solution for chitosan fractionated by gel filtration. The weight-average molecular weight of each fraction was measured by the light-scattering method. The values obtained area=0.59 andK=0.119 cm3 g−1. The molecular weightsMw andMn for fractionated chitosan were measured by GPC. The value ofMw by GPC was much different from that by light scattering and, therefore, a universal calibration procedure was applied to the data by GPC. It was concluded that, also in the case of a cationic polysaccharide such as chitosan, the universal calibration procedure is effective for obtaining the reliable molecular weight by GPC.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 48 (1990), S. 105-108 
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An alternative form of the constraint characterizing the motion of a rigid rotator is introduced and is shown to lead to the same constrained Hamiltonian system as the one constructed with the conventional constraintx 2=constant. In this new formulation, the canonical pairs of phase-space variables can easily be found, and the relationx 2=constant appears through an equation of motion rather than through a constraint. Application toO(N) nonlinear sigma model is also discussed.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 278 (2000), S. 84-89 
    ISSN: 1435-1536
    Keywords: Key words Hyaluronate ; Depolymerization ; Phenothiazines ; Sulfacetamide ; UV irradiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Phenothiazines (promazine, promethazine, chlorpromazine) and sulfacetamide, known as phototoxic drugs, depolymerize aqueous sodium hyaluronate (HA) on exposure to light. The reduction in the HA molecular weight was followed by size-exclusion chromatography with low-angle laser light scattering. In the low-concentration region of the drugs below 0.05 mM, the rate constants of depolymerization increased. The molecular weight of HA was practically unchanged without UV irradiation in the presence of drugs or with UV irradiation in the absence of drugs, indicating the phenothiazines and sulfacetamide require photoenergy to yield any kind of damaging chemical species for HA depolymerization. An involvement of active oxygen radicals in the effects of promazine and promethazine was evidenced by inhibition under anaerobic conditions. Further, addition of mannitol controlled the reaction in the presence of oxygen, pointing to hydroxyl radicals as the damaging agent. Chlorpromazine and sulfacetamide preferably depolymerized HA under anaerobic conditions, suggesting the participation of hydrated electrons.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 111 (1998), S. 453-461 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper contains three results. First, the rate constants for the tunneling reaction HD + D → H + D 2 in solid HD increase steeply with increasing temperature above 5 K, while they are almost independent of temperature below 5 K. A mechanism of a vacancy–assisted tunneling reaction is proposed to account for this temperature dependence. Second, a hydrogen atom and a hydrogen molecule form a van der Waals complex in the Ar matrix at 20 K, where the tunneling reaction HD + D →H + D 2 takes place in this complex. The analysis of well–resolved ESR spectra of the complex determined the distance between a hydrogen atom and a hydrogen molecule as 2.3 – 2.5 Å. Third, the decay rate constants of $${\text{H}}_{\text{2}}^ - $$ anions in solid parahydrogen decrease with decreasing temperature below 6.6 K, attain the minimum value at 5 K, and then increase with decreasing temperature in the range of 5 → 2.7 K. The abnormal temperature dependence of the decay rate constants below 5 K is ascribed to a phonon–scattering process of quantum diffusion.
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