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  • Chemistry  (20)
  • General Chemistry  (4)
  • 78.20.Dj
  • AMS(MOS)
  • 1985-1989  (17)
  • 1975-1979  (5)
  • 1
    Electronic Resource
    Electronic Resource
    An algorithm to compute a sparse basis of the null space (1985)
    Springer
    Numerische Mathematik 47 (1985), S. 483-504 
    Details
    ISSN: 0945-3245
    Keywords: AMS(MOS) ; 65F30 ; CR: G1.3
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary LetA be a realm×n matrix with full row rankm. In many algorithms in engineering and science, such as the force method in structural analysis, the dual variable method for the Navier-Stokes equations or more generally null space methods in quadratic programming, it is necessary to compute a basis matrixB for the null space ofA. HereB isn×r, r=n−m, of rankr, withAB=0. In many instancesA is large and sparse and often banded. The purpose of this paper is to describe and test a variation of a method originally suggested by Topcu and called the turnback algorithm for computing a banded basis matrixB. Two implementations of the algorithm are given, one using Gaussian elimination and the other using orthogonal factorization by Givens rotations. The FORTRAN software was executed on an IBM 3081 computer with an FPS-164 attached array processor at the Triangle Universities Computing Center and on a CYBER 205 vector computer. Test results on a variety of structural analysis problems including two- and three-dimensional frames, plane stress, plate bending and mixed finite element problems are discussed. These results indicate that both implementations of the algorithm yielded a well-conditioned, banded, basis matrixB whenA is well-conditioned. However, the orthogonal implementation yielded a better conditionedB for large, illconditioned problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01389453
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  • 2
    Electronic Resource
    Electronic Resource
    Reduction of optical absorption at a wavelength of around 0.8 μm in LPE garnet (TmBiCa)3(FeGaPt)5O12 (1985)
    Springer
    Applied physics 38 (1985), S. 281-284 
    Details
    ISSN: 1432-0630
    Keywords: 78.20.Dj ; 68.55.+b ; 78.20.Ls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Liquid-phase epitaxy (LPE) garnet films (TmBiCa)3(FeGaPt)5O12 have been grown using only Bi2O3 as the flux so that the film containing Bi gives high specific Faraday rotation. The film does not contain Pb, which may affect optical absorption. The optical absorption coefficientα at 810 nm has been effectively reduced by doping Ca in the melt. Our data show that a minimum level ofα and of the anisotropy constantK u and also the maximum of the electrical resistivityϱ are achieved when Ca2+ replaces Fe2+. Fe2+ results from Pt4+ incorporation in the film due to a Bi2O3 flux attack on a Pt crucible. Using a compensated film,α of 58 cm−1 and a figure of merit of 9deg/dB were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616064
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  • 3
    Electronic Resource
    Electronic Resource
    Incorporation of a well-defined polyether side-chain into segmented poly(ether-urethane urea) and examination for blood-compatibility (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 172 (1989), S. 177-183 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wird eine neue Methode zur Einführung von hydrophilen Polyetherseitenketten in segmentierte Polyurethane unter Verwendung eines Polypropylenoxid-Macromeren mit 1,3-Diol-Gruppen an einem Kettenende, die als Kettenverlängerer fungieren, beschrieben. In diesem Prozeß wird eine Seitenkette quantitativ und direkt in medizinische Polyurethanelastomere eingebaut. Diese Entwicklung ist auch für Biowerkstoffe in künstlichen Organen von Interesse.
    Notes: A new method of introducing a hydrophilic polyether side chain into segmented polyurethane using a polypropylene oxide macromer with 1,3-diol at one chain-end, which behaves as chain extender, is described. In this procedure, a molecular-designed side-chain is incorporated quantitatively and directly into polyurethane biomedical elastomer. The design is also of interest to biomaterials in artificial organs.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1989.051720115
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  • 4
    Electronic Resource
    Electronic Resource
    New catalysts for the oxidative polymerization of 2,6-dimethylphenol, 2.Part 1: cf.7. Complexes of manganese with toluene-3,4-dithiol and with 2,3-dimercaptomaleodinitrileDedicated to Prof. Dr. Georg Manecke for his 60th birthday (1977)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 178 (1977), S. 733-740 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It was found that the manganese complex formed from toluene-3,4-dithiol and MnCl2 (Mn-TDT) and the complex formed from disodium 1,2-dicyanoethylenedithiolate (maleonitriledithiol) (Mn-MNT) show high activities as catalysts for the oxidative polymerization of 2,6-dimethylphenol. Mn-TDT is active only in the presence of an alkaline agent such as potassium hydroxide. Its activity is still higher when it is synthesized in ethanol and isolated just before use. Mn-MNT is similarly active without being isolated, and it is active even in the absence of potassium hydroxide when the mole ratio MNT/Mn is high. This is probably due to the alkaline character of MNT. Mn-TDT or Mn-MNT complex produce poly[oxy(2,6-dimethyl-1,4-phenylene)] selectively, and no formation of the diphenoquinone 2,2′,6,6′-tetramethyl-1,1′-dioxo-4,4′-bicyclohexa-2,5-dienylidene was observed.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1977.021780310
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  • 5
    Electronic Resource
    Electronic Resource
    The formation of a coloured complex of partially saponified poly(vinyl acetate) with iodine in the presence of potassium iodide (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 3221-3230 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der rot-violette Komplex, der sich aus teilverseiftem Polyvinylacetat und Jod in Gegenwart von Kaliumjodid bildet, wurde mit der Benesi-Hildebrand-Methode untersucht. Der molare Absorptionskoeffizient des Komplexes beim Absorptionsmaximum (488 nm) betrug 4,74.104l/(mol cm) bei 10°C und fiel mit steigender Temperatur. Die Konzentration der aus Vinylacetat resultierenden Bausteine (Acetoxyäthylen-Bausteine), die an der Komplex-Bildung mit Jod teilnehmen können, lag unter 1% der Gesamtmenge an Acetoxyäthylen-Bausteine. Die Enthalpie- (ΔH) und Entropie-Änderung (ΔS) wurden zu -45,01 kJ mol-1 (-10,75 Kcal/mol) bzw. -48,40 J mol-1 K-1 (-11,56 cal mol-1 K-1) bei 15°C bestimmt.
    Notes: The red-violet complex which was formed from partially saponified poly(vinyl acetate) and iodine in the presence of potassium iodide was investigated by the Benesi-Hildebrand method. The molar absorption coefficient of the complex at the absorption maximum (488 nm) was found to be 4,74.1041/(mol cm) at 10°C and to decrease with rising temperature. The concentration of units resulting from vinyl acetate (acetoxyethylene units), which can take part in the complex formation with iodine, was below 1% of the total content of acetoxyethylene units in the polymer. The changes of enthalpy (ΔH) and entropy (ΔS) were found to be -45,01 kJ mol-1 (-10,75 Kcal/mol) and -48,40 J mol-1 K-1 (-11.56 cal mol-1 K-1) at 15°C, respectively.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021761108
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  • 6
    Electronic Resource
    Electronic Resource
    Dioxygen sensitivity of a photoexcited thin film of phthalocyanine dispersed in poly(N-vinylcarbazole) (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 2419-2423 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thin films (thickness 0,3 μm) of a mixture of phthalocyaninatozinc(II) (1) and poly(1-vinylcarbazole) (2) are prepared by coating from a solution on ITO glass. The blue coloured films are investigated in an electrochemical cell under irradiation with visible light. In the presence of dioxygen from air the films exhibit an intensive cathodic photocurrent. The action spectrum of the photocurrent corresponds to the absorption spectrum of the phthalocyanine. The results show a device which can be switched by air and visible light.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021891019
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  • 7
    Electronic Resource
    Electronic Resource
    New catalysts for the oxidative polymerization of 2,6-dimethylphenol, 1. Copper complex of toluene-3,4-dithiolDedicated to Prof. Dr. Georg Manecke for his 60th Birthday (1977)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 178 (1977), S. 723-731 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It was found that a copper complex of toluene-3,4-dithiol (Cu-TDT) catalyzes the oxidative polymerization of 2,6-dimethylphenol (1), and the catalytic behavior was studied. The activity of the Cu-TDT is higher than that of the known copper(II)-pyridine complex. The higher the pyridine content in the solvent mixture pyridine/o-dichlorobenzene, the higher is the activity of Cu-TDT. Cu-TDT loses its activity gradually in pyridine solution, however, about 40% of its activity remains even after 150h. The reasons for the high activity are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1977.021780309
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of amine structure on the photopotential induced by dye / polyamine systems (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 1277-1283 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It was found that the photoredox system, dye/poly(iminoethylene) (PEI) induces a remarkably higher photopotential than the corresponding dye/monoamine system. The relationship between the photopotential induced by thionine (TH)/PEI and the number of amino or imino groups in the amine molecule is characterized by an alternating pattern. From the dependencies of the photopotential and the ionic species of the amine on pH, it was concluded that the active species of the amine is the half-protonated one. As a possible mechanism for the high photopotential induced by the polyamine system, an interaction between the dye and the half-protonated species is proposed, based on the bifunctional behavior of the adjacent protonated and unprotonated imino groups of PEI.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790515
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  • 9
    Electronic Resource
    Electronic Resource
    Photoredox polymer with incorporated thionine and alkylenepolyamine capable of inducing photopotential (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 2431-2438 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new type of photoredox polymer with incorporated thionine, (7-amino-3H-phenothiazin-3-iminium chloride). (TH) and alkylenepolyamine groups was prepared by the reaction of poly(acrylic acid) with TH and alkylenepolyamines such as ethylenediamine (en), tetraethylenepentamine (3,6,9-triazaundecane-I,II-diamine), (tetraen) and poly(iminoethylene). The photoredox polymers were able to induce photopotential in aqueous solution in the absence of any other redox reagents. The polymers from TH with on and with tetraen induced photopotentials of 180 mV and 167 mV, respectively. The photopotential of the former system was much higher than that of the system, TH/en. The induced photopotential of the polymer systems did not depend so much upon the mole ratio [en]/[TH] of the pendent groups, while the photopotential of the TH/en system was strongly dependent upon [en]/[TH]. Effects of the polymer structure were discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021791009
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  • 10
    Electronic Resource
    Electronic Resource
    Quenching of the excited state of membranes having polymerpendant tris(2,2′-bypyridine)ruthenium(II) groups by methylviologen and dioxygen (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2011-2017 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Quenching of the excited state of copolymer-pendant Ru(bpy)2+3 membranes by methylviologen (MV2+) and dioxygen was studied and its application proposed. The copolymers used were the copolymer of styrene (St) and 4-methyl-4′-vinyl-2,2′-bipyridine (Vbpy) and that of methyl methacrylate (MMA) and Vbpy. The copolymer-pendant complexes were prepared by reaction of the St- and MMA-copolymers with cis-Ru(bpy)2Cl2. The excited state of the St-copolymer complex membrane was not quenched by MV2+ solution in aqueous medium, but quenched in methanol. The excited state of the MMA-copolymer complex membrane was not quenched by MV2+ neither in water nor in water/methanol mixture. The excited state of St-copolymer complex membrane was not quenched by dioxygen in water, but in methanol. The excited state of MMA-copolymer complex membrane was quenched by dioxygen both in water and water/methanol mixture. The quenching by dioxygen can be used to measure the oxygen concentration in solutions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880823
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