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  • Chemistry  (34)
  • General Chemistry  (4)
  • 78.20.Dj
  • AMS(MOS)
  • 1985-1989  (17)
  • 1980-1984  (19)
  • 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
    Synthesis and photochemical behavior of polynuclear dithiolato-metal-dye complexesDedicated to Prof. Dr. Georg Manecke of the Free University of Berlin for his 65th birthday (1981)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 105-112 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polynuclear dithiolato-metal-dye complexes were prepared and their photochemical behaviors were studied. The dimercapto ligands used were maleonitriledithiol (MNT) and toluene-3,4-dithiol (TDT); metal ions were copper, manganese and nickel; and dyes were thionine (TH), tolusafranine (SAF) and methylene blue (MB). From IR spectra, elemental analyses and magnetic measurements they were found to be polynuclear complexes having bis(dithiolato)-metal structure incorporating the dyes as cations. The complexes showed almost the same visible spectra as the free dyes. The molar absorption coefficients of the maximum absorption were in most cases larger than in the free dye. The dithiolato-metal complex affected remarkably the photochemical reactivity of the dye incorporated in it. The rates of the photochemical reduction of the TH complexes (Cu-MNT-TH, Mn-MNT-TH and Cu-TDT-TH) in hexamethylphosphortriamide were higher than the free TH, while those of the SAF complexes (Cu-MNT-SAF and Mn-MNT-SAF) and MB complexes (Cu-MNT-MB and Ni-MNT-MB) were much lower than the free SAF and MB, respectively.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1981.021820113
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  • 5
    Electronic Resource
    Electronic Resource
    Solid phase photoreduction of methylviologen on cellulose (1981)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 1111-1118 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Methylviologen (1,1′-dimethyl-4,4′-bipyridinium dichloride, MV2+) absorbed on cellulose paper can be reduced photochemically in solid phase. The ESR spectrum (singlet; g = 1,967, ΔHmsl = 13,5 gauss) shows the photochemical formation of its cation radical (MV•+). The MV•+ formed on cellulose is unusually stable against oxidation by oxygen. Photochemical formation and slow oxidation of MV•+ under air occur fairly reversibly. The concentration of MV•+ and the optical density (O.D.) at 620 nm show a linear relationship. The concentration of MV•+ at 1 O.D. corresponds to 1,07.10-8 spins/cm2 cellulose paper. The formation of carbonyl groups in MV2+/cellulose after irradiation indicates that cellulose acts as electron donor. The mechanism of the solid phase photoreduction is discussed in relation to the effect of other carbohydrates or inorganic materials as adsorbents.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1981.021820411
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  • 6
    Electronic Resource
    Electronic Resource
    Catalytic activity of polynuclear manganese-thiolato complexes for oxidative polymerization of 2,6-dimethylphenol (1981)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 101-104 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Chelating thiolato-manganese complexes of 1,2-dimercaptoethane (DME), 3,4-dimercaptotoluene (DMT), cystein (Cys), β-mercaptoethyl alcohol (ME), β-mercaptoethylamine (MEA), and mercaptoacetic acid (MAA) showed high activity for the oxidative polymerization of 2,6-dimethylphenol (DMP) as heterogeneous catalysts. The complexes caused only C—O coupling to give poly[oxy(2,6-dimethyl-1,4-phenylene)] selectively. From the reaction in the absence of oxygen it was concluded that oxygen acts as electron-accepting ligand. The much higher activity of DMT complex, compared with that of DME complex, was considered to be due to the π-accepting character of the ligand. The MEA complex which showed especially strong spin-spin interaction in the ESR spectrum exhibited also high activity.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1981.021820112
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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of new polynuclear manganese-thiolato complexes (1981)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 89-99 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: New polynuclear manganese-thiolato complexes were prepared by reaction of Mn ions with chelating mercapto compounds, such as 1,2-dimercaptoethane (DME), 3,4-dimercaptotoluene (DMT), cystein (Cys), β-mercaptoethyl alcohol (ME), β-mercaptoethylamine (MEA), and mercaptoacetic acid (MAA). Potassium permanganate formed stable complexes with DME, DMT and Cys. The complexes of ME, MEA and MAA were prepared by the reaction with manganous chloride. The temperature dependencies of the magnetic susceptibility of the complexes, except Cys, obeyed the Curie-Weiss law, indicating strong antiferromagnetic interaction between the spins on the Mn ions. The valence of the DME and DMT complexes was calculated to be IV to V, and that of the Cys, ME, MEA and MAA complexes to be II to IV. ESR spectra of the DME and DMT complexes showed broad singlet absorptions, while those of ME, MEA and MAA complexes exhibited narrow Lorentzian singlets, both types indicating strong interaction between the spins. These results and the composition indicated polynuclear complexes containing μ-oxo (DME and DMT), μ-chloro or μ-thiolato (ME, MEA and MAA) structure, while Cys gave mononuclear complex.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1981.021820111
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  • 9
    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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  • 10
    Electronic Resource
    Electronic Resource
    Formation, characterization, and catalytic activities of polymer-metal complexes (1981)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science: Macromolecular Reviews 16 (1981), S. 397-522 
    Details
    ISSN: 0076-2083
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 49 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.230160107
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