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  • 1
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International orthopaedics 10 (1986), S. 89-93 
    ISSN: 1432-5195
    Keywords: Fractures ; Children ; Femoral shaft ; Overgrowth determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les auteurs ont réalisé une étude prospective des fractures de la diaphyse fémorale chez les enfants de moins de 14 ans. Elle a porté sur 71 patients qui ont été revus cliniquement et radiologiquement à intervalles d'un an. Les données recueillies ont fait l'objet d'analyses uni- et multivariantes. L'hyperallongement du fémur a atteint 8,63 mm en moyenne (de 1 à 21 mm). Il est influencé par l'âge (il est plus important chez les enfants de 3 à 9 ans), par le déplacement initial (il est plus marqué dans les fractures à grand déplacement), et par le chevauchement des fragments lors de la consolidation (l'importance de l'allongement varie en raison inverse de celle du chevauchement). La connaissance de ces facteurs permet de prévoir le degré d'hyperallongement au moment même de la fracture. Cet allongement survient chez tous les enfants de plus de 2 ans, et surtout pendant la première année d'évolution. Il se poursuit, mais plus lentement, pendant la deuxième année et même jusqu'à la cinquième année dans 27% des cas. Ensuite, chez tous les enfants, les deux fémurs continuent à croître de façon égale. L'allongement du tibia homolatéral n'a été observé que chez 60% des enfants, il était en moyenne de 1,05 mm (de 1 à 5 mm).
    Notes: Summary A prospective study of femoral shaft fractures in children under the age of 14 years has been carried out in 71 patients who were reviewed both clinically and radiographically at yearly intervals. The processing of data has been carried out by univariate and multivariate analysis. Femoral overgrowth (F.O.) averaged 8.63 mm (range 1–21 mm), and was found to be influenced by age (greater overgrowth in children between 3 and 9 years), the initial displacement of the fracture (greater overgrowth in severely displaced fractures), and overriding of the fragments at the time of healing (the greater the overriding the lesser the overgrowth). Consideration of these factors allowed overgrowth to be predicted from the time of fracture. Overgrowth occurred in all children over 2 years of age, and took place mainly during the first year after the fracture. It continued, although to a lesser extent, during the second year, and for as long as the fifth year in 27%. After this time the growth rate of both femurs was equal in all the children. Ipsilateral tibial overgrowth was present in only 60% of the children and averaged 1.05 mm (1–5 mm).
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Bacillus licheniformis MIR 29 has been isolated and produces extracellular proteases. It is able to grow at temperatures up to 60 °C and at pH values up to 9.0. Casein was the best carbon source for production of a thermostable protease activity which, in some conditions, is 90% extracellular. The synthesis of alkaline protease is not constitutive; different levels of production were found with different carbon and nitrogen sources. Casein was thought to be an inducer of enzyme synthesis. The optimal pH and temperature of the enzyme activity were 12 °C and 60 °C, respectively. The enzyme was stable up to 60 °C in the absence of stabilizers. The protease activity was inhibited with phenylmethylsulphonyl fluoride, indicating a serine-protease activity. The proteolytic activity was lowered by molecules present in the culture supernatant, which include amino acids and peptides, indicating end-product inhibition. Electrophoresis assay on denaturating gels showed two bands with alkaline protease activity, in the 25 to 40-kDa molecular mass range.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-4986
    Keywords: Polysialic acid biosynthesis ; Pasteurella haemolytica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The capsular polysaccharide of Pasteurella haemolytica A2 consists of a linear polymer of N-acetylneuraminic acid (Neu5Ac) with α(2–8) linkages. When the bacterium was grown at 37°C for 90 h in 250 ml shake flasks at 200 rpm in Brain heart infusion broth (BHIB), it accumulated, attaining a level of 60 μg/ml. Release of this polymer was strictly regulated by the growth temperature, and above 40° no production was detected. The pathway for the biosynthesis of this sialic acid capsular polymer was also examined in P. haemolytica A2 and was seen to involve the sequential presence of three enzymatic activities: Neu5Ac lyase activity, which synthesizes Neu5Ac by condensation of N-acetyl-D-mannosamine and pyruvate with apparent Km values of 91 mM and 73 mM, respectively; a CMP-Neu5Ac synthetase, which catalyzes the production of CMP-Neu5Ac from Neu5Ac and CTP with apparent Km values of 2 mM and 0.5 mM, respectively, and finally a membrane-associated polysialyltransferase, which catalyzes the incorporation of sialic acid from CMP-Neu5Ac into polymeric products with an apparent CMP-Neu5Ac Km of 250 μM.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 13 (1993), S. 197-201 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: 515 microorganisms of the genus Bacillus which produce starch-degrading enzymes were isolated from natural environments in the course of a screening programme. Treating the Bacillus strains on agar plates with iodine reagent for 30 seconds led to the selection of clones with increased amylolytic activity. This methods is very convenient for the screening of large numbers of amylolytic strains.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2131-2141 
    ISSN: 0887-624X
    Keywords: polypropylene, catalyst dynamics for ; Ziegler-Natta ; heterogeneous catalysis of; catalysis ; polyolefins, fragmentation of ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recently considerable detail has become available on the initial morphology and the morphological changes that occur for silica based Cr catalysts for ethylene polymerization. These catalysts are produced as a dry powder and may be employed either in gas phase or in slurry processes. MgCl2-supported Ziegler-Natta polymerization catalysts are often prepared and employed as slurries. They usually are never dried and thus few studies have employed the spectra of physical techniques common to the characterization of pore structure. In the current study, we have carefully removed the solvent for both ball-milled and precipitated MgCl2-supported catalysts. These catalysts are characterized by physical sorption, mercury porosimetry, and electron microscopy both as prepared and during the initial stages of polymerization (to ∼ 100 g of polymer/g of catalyst). We find that the initial catalyst may be represented by a complex agglomerate of small crystallites as contrasted with the branched pore network found in Cr/silica catalysts. As a result, it is concluded that the initial fragmentation of the MgCl2 based systems is more uniform as contrasted with the progressive fragmentation of the silica-based system. This fragmentation mechanism facilitates the retention of greater polymer/catalyst surface during the initial stages of the polymerization. © 1992 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 2507-2512 
    ISSN: 0887-624X
    Keywords: polyolefin catalysis ; tomography ; catalyst/polymer morphology ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Drastic changes occur during the initial stages of the α-olefin polymerization over heterogeneous catalysts. Fragmentation of the support takes place as polymer is formed at the active sites within the voids of the support/catalyst. Magnesium chloride-supported titanium catalyst/polymer particles have been analyzed employing high-resolution computed microtomography (CMT) using synchrotron radiation at Brookhaven National Laboratory. The changes in morphology, the spatial distribution of the support/catalyst fragments, porosity, and polymer distribution in single growing polypropylene and polyethylene particles have been studied. These studies documented considerable macroporosity ( 〉 2 μm in size) within the growing catalyst/support/polymer particles. The largest pores may be due to agglomeration of smaller subparticles. Our results confirm that the initial fragmentation of the support proceeds readily and uniformly to yield a multi-grain growth of subparticle agglomerates. The support/catalyst fragments appear to be distributed relatively uniformly within the growing polymer particle. The surface of the subparticle agglomerates is accessible through the void-space between growing catalyst/particle grains. This may facilitate monomer transport to the activate sites through the polymer/catalyst particles. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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