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  • 1970-1974  (20)
  • Polymer and Materials Science  (14)
  • Analytical Chemistry and Spectroscopy  (6)
  • Organic Chemistry
  • 1
    Electronic Resource
    Electronic Resource
    Poly(vinyl alcohol) hydrogels. Formation by electron beam irradiation of aqueous solutions and subsequent crystallization (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 17 (1973), S. 3779-3794 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Aqueous solutions of poly(vinyl alcohol) were submitted to varying doses of electron beam irradiation. By modification of the classical Flory-Huggins equations appropriate to the initial state of solution of the polymer, the molecular weight between crosslinks, Mc, was calculated as a function of radiation dose, initial polymer concentration, and temperature. Following crosslinking in the solution state, crystallization was induced by dehydrating the network at temperatures above 90°C. Following dehydration, the polymer network was reequilibrated with water and its tensile properties compared with identically prepared hydrogels not subjected to crystallization by dehydration. Greatly enhanced values of ultimate tensile strength and resistance to tear result from the treatment producing crystallization, compared with those of the crosslinked but not previously dehydrated gels.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1973.070171219
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  • 2
    Electronic Resource
    Electronic Resource
    Poly(vinyl alcohol) hydrogels for synthetic articular cartilage material (1973)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 7 (1973), S. 431-443 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: As part of a program to develop a synthetic articular cartilage material for use in reconstructive joint surgery, this paper is concerned with the desiderata for such a material and with the properties of poly (vinyl alcohol) hydrogels reinforced by crystallinity as developed for this purpose. Reference is further made to the ultimate preparation of cationic PVA hydrogels to provide the low-friction lubrication necessary in a cartilage prosthesis when in contact with natural synovial fluid.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820070506
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Dynamic mechanical relaxation effects in some poly(arylene sulfones) (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1169-1175 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly-4,4′-oxydiphenylenesulfonyl and poly-4,4′-methylenediphenylenesulfonyl were synthesized by an electrophilic substitution polymerization of the arylene monosulfonyl chloride monomers. The glass-transition temperatures Tg of these polymers were determined by calorimetric and dynamic mechanical measurements, and the number-average molecular weights were determined by vapor-pressure osmometry. Both polymers were found to have the same Tg at equivalent molecular weight; the limiting value at high molecular weight is 238°C. Both polymers have two dynamic mechanical relaxation peaks at temperatures far below Tg. One is in the neighborhood of 0°C, and the other is at -110°C. Plausible origins for these relaxations, and the absence of any near 0°C in poly(4,4′-isopropylidenediphenylene-co-4,4′-sulfonyldiphenylene dioxide), are discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080711
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  • 4
    Electronic Resource
    Electronic Resource
    Mass spectrometric study of 1-chloro-2-nitrosocycloalkanes, dimers in gaseous phase (1970)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1970), S. 1055-1066 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron-impact mass spectra and the field ionization mass spectra of 1-chloro-2-nitrosocyclohexane and 1-chloro-2-nitrosocyclopetane are presented and discussed. The two compounds investigated exist in dimeric form in the gaseous phase.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210030810
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  • 5
    Electronic Resource
    Electronic Resource
    Mass spectra and pyrolysis of phenarsazine derivatives (1970)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 4 (1970), S. 503-512 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five phenarsazine derivatives with arsenic in the trivalent state and the pentavalent state are studied by mass spectrometry. Their characteristic fragmentation modes and the fragment ions with common structures are discussed. Experimental results show that the pyrolytic decompositions of the phenarsazine derivatives are closely parallel to the unimolecular ion fragmentation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210040151
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  • 6
    Electronic Resource
    Electronic Resource
    Interlocked DNA rings. II. Physicochemical studiesThis Work has been supported by a grant GM14621 from the U.S. public Health Service, and a fellowship from the Alfred P. Sloan Foundation. (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 489-502 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several species of topologically interlocked λb2b5c DNA rings (catenanes) have been prepared in vitro. The sedimentation behavior of dimeric catenanes containing 0, 1, or 2 covalently closed duplex rings has been studied as a function of the superhelical density of the covalently closed ring or rings. In general, if XtpY represents rings X and Y topologically interlocked, the sedimentation coefficient of this species, SXtpY, is related to the sedimentation coefficients SX and SY of the component rings by the empirical relationship SXtpY/SY = [(MX + MY)/MY] [1 + (MX/MY)1.78(SY/SX)1.78]-0.56This equation can also be extended to the case where three monomeric rings are topologically linked in a chain. For two topologically interlocked monomeric rings with neither ring covalently closed, the sedimentation coefficient is 1.35 times that of the monomeric ring. This is different from results reported for mitochondrial and P22 catenanes by others. Several possibilities are discussed to account for this discrepancy. The sedimentation coefficient of a species containing one covalently closed duplex ring and a single-stranded ring was also measured in an alkaline medium. This species, which can be easily derived from a dimeric catenane containing two covalently closed duplex rings, is particularly useful for the identification of covalently closed dimeric catenanes. Some electron microscopic studies of these interlocked rings are presented in an accompanying paper.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1970.360090410
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  • 7
    Electronic Resource
    Electronic Resource
    Influence of telopeptide on the morphology and physicomechanical properties of reconstituted collagens (1973)
    New York : Wiley-Blackwell
    Biopolymers 12 (1973), S. 2045-2055 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The morphology and physicomechanical properties of two types of collagen membranes, one of which does not have telopeptides, were compared with small-angle light scattering, rheo-optical, dynamic mechanical, and dynamic rheo-optical techniques. The presence of telopeptides in native collagen allows the formation of larger rod-like superstructures; it renders the membrane more resistant to irreversible deformation yet more responsive to dynamic mechanical perturbation. Telopeptides are also responsible for relaxation at room temperature, and impart more linearly elastic properties to the material as compared to membranes derived from enzyme-treated collagens.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1973.360120911
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  • 8
    Electronic Resource
    Electronic Resource
    Dynamic mechanical and rheo-optical studies of collagen and gelatin (1972)
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2015-2031 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The frequency dependence of dynamic mechanical properties of rat tail tendon (RTT), enzyme-solubilized collagen membranes (ESC), AKM-23 dialysis membranes, and gelatin film have been measured at 110, 11, and 3.5 Hz from - 160 to 220°C. RTT and AKM-23 are devoid of a rubbery region; there are as many as six mechanical loss transitions. Gelatin and ESC membranes behave as rubbery materials above room temperature; only three tan δE peaks can be resolved for these materials. Strain birefringence was used to measure the crystalline and amorphous contribution of orientation induced by strain. Both the birefringence and the strain optical coefficient are sensitive to the amount of water in a sample. The effect of chemical swelling agents and of annealing on birefringence are described. Stress relaxation data on gelatin film were analyzed with the rubber elasticity theory to give the average number of chains per unit volume, the specific polarizability, the stress-birefringence ratio and the average molecular weight between hydrogen bonds were calculated. The intrinsic amorphous birefringence for “wet” gelatin film is 1.25 × 10-2; it is estimated to be about 6 × 10-2 for “dry” gelatin film.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1972.360111003
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  • 9
    Electronic Resource
    Electronic Resource
    The effect of ions on the superstructures of reconstituted collagen (1973)
    New York : Wiley-Blackwell
    Biopolymers 12 (1973), S. 1063-1069 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of a variety of electrolytes on the stabilization and destabilization of the rod-like superstructures in reconstituted collagen membranes have been studied by small-angle light scattering (SALE). Structural orders at two levels are effected: association-disassociation at the micron level and the helix-coil transitions at the mollecular level. In addition to lyotropic salts, several transition metal ions were also studied. They act to disassociate collagen aggregates by the formation of stable complexes.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1973.360120510
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  • 10
    Electronic Resource
    Electronic Resource
    Proton magnetic resonance studies of the conformational changes of dideoxynucleoside ethyl phosphotriestersPart II of a series entitled Alkyl Phosphotriesters of Dinucleotides and Oligonucleotides. (1973)
    New York : Wiley-Blackwell
    Biopolymers 12 (1973), S. 2225-2240 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: PMR investigations on the diastereomeric phosphate methyl protons of the dinucleoside ethyl phosphotriesters Tp(C2H5)T, dA, and dIp(C2H5)dI have been used to study the conformational changes of these dimersin solution. In D2O (273°K), the diastereomeric phosphate-methly groups of Tp(C2H5)T appear as a triplet. The methyl resonances of dIp(C2H5)dI and dAp(C2H5)dA appear as two sets of triplets and their chemical shift differences (δ1 - δ2), decrease with increasing temperature, finally becoming zero at 292°K and 333°K, respectively. The same phenomenon is observed for dAp(C2H5)dA in CD3OD; in this detacking solvent, the difference (δ1 - δ2) diminishes to zero at a lower temperature (261°K). At room temperature in D2O, the chemical shift of the phosphate methyl of Tp(C2H5)T appears at lower field than those of dIp(C2H5)dI or dAp(C2H5)dA. The differences between the chemical shifts of these groups (δI - δT or δA - δT) increase with increasing temperature, and reach maximal values at 301°K and 333°K, respectively. The results suggest that at low temperature the largest fraction of the dimer population exists in a stacked state, with the phosphate-ethyl groups outside the stack. Increasing temperature causes an oscillation of the bases and a shift in the dimer population away from the stacked state. Finally at high temperature, the planar bases rorate with respect to one another and in the case of dIp(C2H5)dI and dAp(C2H5)dA, the ethyl groups experience shielding by the anisotropic ring current of the five-membered ring of the bases. Thus, the current pmr studies and those reported earlier from our laboratory support an “oscillation-rotation model” for the unstacking process of the dimers. The relationship of this model and the “two-state model” is discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1973.360121004
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