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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Theory and Simulations 7 (1998), S. 257-261 
    ISSN: 1022-1344
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: New scaling laws for chain networks are derived to describe the fundamental relationships between the viscosity exponent (k), viscoelastic exponent (m), stretched exponent (β), spatial dimension (d). fractal dimension (df), and a universal constant (γ). The scaling of the total number of monomers and the radius of gyration is defined by df. We have discovered γ = m/β to be a universal constant which relates the shear modulus of a polymer gel melt to the shear modulus near the glass transition. Analyzing the size-dependent shear viscosity, we have determined γ = 3dfcd/(7d-5dfc) = 2.647 for d = 3 where dfc is the fractal dimension of critical clusters at the gel point. By using γ, the present theory extends previous work pertaining to systems near the sol-gel transition, and shows how properties far from the critical point can be explained. The theoretical prediction is in good agreement with viscoelastic measurements.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 197 (1996), S. 1-17 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ring-opening polymerization of 2-methyl-2-oxazoline initiated by 2-(p-nitrobenzenesulfonato)ethyl methacrylate follows the so-called “living mechanism”, i.e. fast initiation compared to slow propagation and no chain transfer. Accordingly, methacryl macromonomers having homopolymers, block or random copolymers of 2-methyl and 2-pentyl-2-oxazoline backbones with narrow molecular weight distribution were obtained. Termination of the propagating species by ion-exchange or aminolysis with triethylamine yielded hydroxyl and quaternary ammonium terminated macromonomers, respectively.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Theory and Simulations 4 (1995), S. 397-404 
    ISSN: 1022-1344
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new free volume distribution function for amorphous polymers is derived on the basis of a lattice model. It provides a good description of the non-Gaussian spreading observed very recently in positron annihilation experiments. This new theory shows that the non-Gaussian distribution is a result of the large density fluctuations of holes from their equilibrium. The Gaussian distribution is recovered in the limit of small fluctuations. The size and volume distribution of the holes is uniquely defined by two structural parameters: the energy of hole formation and the lattice volume. Our theory predicts that increases in temperature will broaden the distribution and shift its lower peak to higher free volume. Increases in pressure have the opposite effect.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 43 (1998), S. 428-432 
    ISSN: 0021-9304
    Keywords: BoneSource™ ; hydroxyapatite cement ; biomaterial ; craniofacial skeletal reconstruction ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: BoneSource™-hydroxyapatite cement is a new self-setting calcium phosphate cement biomaterial. Its unique and innovative physical chemistry coupled with enhanced biocompatibility make it useful for craniofacial skeletal reconstruction. The general properties and clinical use guidelines are reviewed. The biomaterial and surgical applications offer insight into improved outcomes and potential new uses for hydroxyapatite cement systems. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 43: 428-432, 1998
    Additional Material: 4 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 35 (1997), S. 273-277 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The calcium phosphate cement (CPC) used in this study was formed by combining equimolar amounts of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA). This powder, when mixed with water, sets to a hard cement in about 30 min. However, the water-based CPC paste is not highly cohesive and is vulnerable to washout until hardening occurs. The objectives of this study were to investigate the effects on handling properties, washout resistance, cement hardening behavior, and mechanical properties of adding several gelling agents to CPC paste. Aqueous solutions that contained a mass fraction of 2-4% of hydroxypropyl methylcellulose (HPMC), carboxyl methyl-cellulose (CMC), chitosan acetate, and chitosan lactate were used as cement liquids. Hardening time was measured by the Gilmore needle test; resistance to washout was evaluated by the disintegration of the cement specimen in water with agitation; and mechanical strength was evaluated by the measurement of diametral tensile strength and compressive strength. Handling properties were greatly improved by the addition of HPMC, CMC, chitosan acetate, and chitosan lactate. Hardening time was retarded by the additions of HPMC and CMC, and mechanical strength was weakened by the addition of either the chitosan lactate or the chitosan acetate. © 1997 John Wiley & Sons, Inc. J. Biomed Mater Res, 35, 273-277, 1997.
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 19 (1995), S. 101-108 
    ISSN: 0308-0501
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Performance of three fire zone models BR12, CCFM.VENTS and CFAST in simulating forced ventilation fires with low heat release and high ventilation rates were studied experimentally. A fire chamber of length 4.0 m, width 3.0 m height 2.8 m with adjustable ventilation rates was used. Burning tests were carried out with wood cribs and methanol to study the preflashover stage of a compartmental fire and the effect of ventilation. The mass loss rate of fuel, temperature distribution of the compartment and the air intake rate were measured. The heat release rates of the fuel were calculated from the measured mass loss rate. The smoke temperature was used as the validation parameter. A scoring system is proposed to compare the results predicted by the three models. An empirical expression for calculating the smoke temperature is assessed. Lastly, the Computational Fluid Dynamics technique is also used for comparing the simulated fire environment.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 21 (1997), S. 235-244 
    ISSN: 0308-0501
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Application of zone model for studying atrium smoke-filling process was evaluated. The fire zone model FIRST was selected as the fire simulator. Studies were focused on the plume model, the geometry of the atria and the heat release rate of fires. Six plume models reported in the literature were reviewed. Their expressions on the velocity, temperature and mass flow were compared. Three halls of same volume but different shapes were taken as the samples. A small volume of 2000 m3 was used because a zone model should work in halls of this size. Numerical simulations of the fire environment in the atrium buildings with those six plume models were carried out using the zone model FIRST. A total number of 108 simulations were performed with nine sets of fires. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 9 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 19 (1995), S. 171-178 
    ISSN: 0308-0501
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The fire risk in Chinese restaurants in Hong Kong is analyzed using the ARGOS fire risk analysis model developed at the Danish Institute of Fire Technology. A sample size of fifteen Chinese restaurants with different floor areas and fire load densities is considered. Fire simulations are performed for two cases by assuming a PU foam furniture fire occurring in the dining hall and a kerosene fire in the kitchen. Correlations are derived between the floor area and the predicted maximum hot gas temperature, the corresponding smoke layer interface height and the cost of damaged stock in the restaurants. The effectiveness of fire protection systems including sprinkler systems and smoke vents in controlling the fire is also discussed.
    Additional Material: 6 Ill.
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  • 9
    Publication Date: 2006-10-26
    Description: Variations of ionospheric electron content during disturbances
    Keywords: FLUID MECHANICS
    Format: text
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