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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 30 (1984), S. 502-504 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 18 (1972), S. 169-173 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gas absorption by eddies at the free surface of a strongly turbulent liquid is interpreted quantitatively in terms of the Levich approach. The mass transfer coefficient is calculated to vary as Re to a relatively high power (1.3 to 1.5).Experiments on free turbulent jets of liquids in gas are in general accord with this theory. For turbulent films of liquids flowing over large roughness elements in “wake-interference” flow, the turbulence is anomalously efective in promoting gas absorption.Traces of surface-active agents suppress the surface renewal. This is analyzed theoretically: the results compare favorably with gas-absorption for stirred cells and flow experiments over smooth plates. For “wake-interference” flow over rough plates, the reduction in the rate of gas absorption by surface-active material is more pronounced than predicted for ordinary turbulence. But even in the presence of a surface-active agent, the roughness still gives an advantage in mass transfer rates as compared with smooth plates.
    Additional Material: 8 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 24 (1978), S. 524-530 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental values of the surface velocities vs of water jets have been obtained by high speed flash cine photography of talc particles on the surfaces of both laminar and turbulent jets. Values of the surface ages as defined variously by Defay and Hommelen (1958), Hansen (1964), and Harper (1973) have been obtained from our data for both pure water and for dilute solutions of surface active agents.We find, by comparison with published entry length corrections for gas absorption, that x/vs gives the most reasonable age of the surface at any distance x along a jet of pure water.If a surface active agent is present in the water, the amount of adsorption of a few millimeters downstream from the nozzle is of the order ten times greater than calculated for laminar jets and five to six times greater than calculated for turbulent jets at Ren = 18 800. This we ascribe to liquid circulation in the jet adjacent to the nozzle, caused by the Marangoni surface flow, which also reduces vs significantly.
    Additional Material: 12 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 21 (1975), S. 599-600 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 334 (1992), S. 34-36 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new, high yield synthesis of [Pd2Cl2(m̈-dmpm)2] (dmpm = bis(dimethylphosphino)methane), which avoids the use of the ill-defined, polymeric substance [PdCl(CO)]n as a starting material, is described. The procedure involves ligand metathesis of [Pd2Cl2(m̈-dppm)2] (dppm = bis(diphenylphosphino) methane) with dmpm using a solvent in which both [Pd2Cl2(m̈-dppm)2] and [Pd2Cl2(m̈-dmpm)2] are only sparingly soluble. Yields of 〉 98% are routinely obtained.
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 5 (1988), S. 116-121 
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aspects of measuring the particle size distribution and median diameters of fine boron powders have been investigated. It has been demonstrated that high concentrations, typically 20 w/o, of wetting agent are necessary in a predispersion stage, especially if the material has a wide range of particle size. Measurements were made with both Coulter counting and a light scattering technique from which it has been demonstrated that for particles of median diameter in the range 10-30 μm, the latter oversizes with respect to the former by as much as 30%.
    Additional Material: 8 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 27 (1993), S. 851-859 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Primary bone cells, isolated from the periosteally stripped calvariae of neonate rats, were cultured on 60Co γ-irradiation-sterilized bacteriologic-grade polystyrene that had been either surface treated with concentrated sulfuric acid or received further γ-irradiation treatments facilitated cell colonization of the polystyrene compared to those surfaces not treated in the laboratory. x-Ray photoelectron spectroscopy (XPS) showed that the two treatments introduced different chemical groups onto the polymer surface and that cell adhesion was related to γ-irradiation in a dose-dependent manner. These results show that simple biologic assays, such as cell colonization, are not able to distinguish between differences in surface chemistry demonstrated by such a routinely employed surface analysis technique. Thus, there is a need to develop more sensitive biologic assays that provide functional information of a precision that can be correlated with subtle changes in substratum surface chemistry. Further, we argue that because cells isolated by tissue digestion using proteolytic enzymes respond more readily to changes in the surface chemistry of the substratum they colonize, compared to explanted cells; biologic assays designed for biomaterials testing must take into account changes effected in cell adhesion behavior by isolation procedures. © 1993 John Wiley & Sons, Inc.
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 28 (1994), S. 105-112 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Cell-mediated resorption of densely sintered hydroxyapatite (HA1250), tricalcium phosphate (TCP), and 600° or 900°C calcined hydroxyapatite (HA600 and HA900, respectively), was investigated by using two culture systems. The first was an osteoclastic cell culture, and the second was a two-stage culture that was composed of a bonelike tissue formation on the substrata in the first stage and its subsequent resorption by osteoclasts in the second stage. Neither of the materials showed resorption or surface alterations in the osteoclastic cell culture, except for some limited phagocytotic activity on HA600 and HA900. In the two-stage culture, production of mineralized extracellular matrix was only observed on HA1250 and TCP, and its subsequent resorption by osteoclastlike cells was evident. Small and occasionally larger tartrate-resistant acid phosphatase positive cells produced 20-150 μm diameter resorption pits in both the mineralized extracellular matrix on HA1250 and TCP and TCP and the surfaces of HA600 and HA900. Resorption of the mineralized extracellular matrix on TCP also resulted in degradation of the underlying ceramic surface, mainly initiating from intergrain boundaries, whereas the surface of HA1250 remained unaltered. The results of this study clearly demonstrate that osteoclastic resorption of calcium phosphates is potentiated in postosteogenic culture conditions. A possible role for bone matrix constituents in cell-mediated resorption is hypothesized, whereas the occurrence of resorption seems to be mainly governed by the combined effects of material characteristics such as grain size and crystal structure. © 1994 John Wiley & Sons, Inc.
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 28 (1994), S. 269-277 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Polyactive®, a polyethylene oxide/ polybutylene terephthalate (PEO/PBT) copolymer, has been reported to display bone-bonding behavior. Although a detailed description of the in vivo bone/ Polyactive® interface is available, the underlying bone-bonding mechanism is still largelyunknown. In this in vitro study, a calvarial envelope method has been adopted to reproduce the in vivo bone-bonding phenomenon and subsequently to obtain information on the biological effect of varying PEO/PBT segment ratios. The following PEO/PBT ratios were examined: 70/30, 60/40, 55/45, 40/60, and 30/70. Light microscopy (LM) and scanning (SEM), transmission (TEM), and backscatter electron microscopy (BSE), as well as X-ray microanalysis (XRMA), were employed. Within the period of analysis (3 weeks), an intimate contact between mineralized deposition and the 70/30, 60/40, and, to a lesser extent, the 55/45 surface was observed. Calcified areas developed within the surface of these PEO/BPT proportions during the culture period. Needle-shaped crystals from the mineralized tissue compartment and from calcified areas within the materials surface were intermingled at the interface, providing a morphologic continuity. A cellular layer was interposed with the mineralization front and the noncalcified 40/60 and 30/70 substrates. Apparently, the percentage of PEO is important for calcification within the near surface of the polymer. This relation is such that the highter the PEO content in PEO/PBT ratios, the more rapid the calcification is considered. The occurrence of material calcification is considered to be largely responsible for the subsequent interfacial interactions. The calvarial envelope culture method allows not only reproduction of the in vivo bone/Polyactive® interface, but also a relatively rapid differentiation within the range of PEO/PBT ratios. It was therefore concluded that this in vitrosystem is suitable for further studies toward a better understanding of the bone/Polyactive® interfacial composition and the underlying mechanisms. © 1994 John Wiley & Sons, Inc.
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 29 (1995), S. 89-99 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Dense, sintered, slip-cast hydroxyapatite rods were implanted transfemorally in young adult rats. The femora were excised after 2 and 4 weeks and, following fixation, either embedded in methyl methacrylate for light microscopy, decalcified and prepared for transmission electron microscopy, or freeze fractured in liquid nitrogen for scanning electron microscopic analysis. The latter was performed on the two tissue fragments that remained after freeze fracturing, from which the first contained the implants and the second comprised tissue that had been immediately adjacent to the hydroxyapatite rods. Undecalcified light microscopic sections revealed extensive bone tissue formation around and in contact with the hydroxyapatite rods. The initial bone matrix apposed to the implant surface, as demonstrated with scanning electron microscopy, was either composed of globular deposits or an organized network of collagen fibers. The deposits, which ranged in size from 0.1-1.1 μm, fused to form a cement-like matrix to which collagen fibers were attached. Degradation of the hydroxyapatite surface resulted in the presence of unidirectionally aligned crystallites, with which the newly formed bone matrix was closely associated. Ultrastructural analysis of the bone-hydroxyapatite interface with transmission electron microscopy revealed a 50-600-nm-wide collagen-free granular zone, comprising one or more 40-100-nm-thick electron-dense layer(s). These structural arrangements most probably partially represent the globular deposits and proteinaceous material adsorbed onto and partially in the degrading hydroxyapatite surface. Although the latter change in surface topography may have enhanced bonding of the cement-like matrix to the hydroxyapatite, the cause for this change in topography and the type of bond formed are, at present, unknown. © 1995 John Wiley & Sons, Inc.
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