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  • Physics  (2,562)
  • Deutschland
  • 2000-2004  (25)
  • 1975-1979  (2,543)
  • 1
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-07-03
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stec, Boguslaw -- New York, N.Y. -- Science. 2004 Jul 2;305(5680):41-4; author reply 41-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15232089" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptation, Biological ; *Cells ; *Life ; Physical Phenomena ; Physics ; Proteins/*chemistry ; Selection, Genetic ; Thermodynamics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-10-09
    Description: Space used by animals increases with increasing body size. Energy requirements alone can explain how population density decreases, but not the steep rate at which home range area increases. We present a general mechanistic model that predicts the frequency of interaction, spatial overlap, and loss of resources to neighbors. Extensive empirical evidence supports the model, demonstrating that spatial constraints on defense cause exclusivity of home range use to decrease with increasing body size. In large mammals, over 90% of available resources may be lost to neighbors. Our model offers a general framework to understand animal space use and sociality.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jetz, Walter -- Carbone, Chris -- Fulford, Jenny -- Brown, James H -- New York, N.Y. -- Science. 2004 Oct 8;306(5694):266-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544-1003, USA. wjetz@princeton.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15472074" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Body Constitution ; Body Weight ; Conservation of Natural Resources ; *Ecosystem ; Energy Metabolism ; Environment ; *Homing Behavior ; *Mammals/anatomy & histology/metabolism ; Mathematics ; *Models, Biological ; Physical Phenomena ; Physics ; Population Density
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-12-18
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉New York, N.Y. -- Science. 2004 Dec 17;306(5704):2012.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15604367" target="_blank"〉PubMed〈/a〉
    Keywords: Access to Information ; Animals ; Biological Warfare ; Ecosystem ; Genome ; Information Dissemination ; Mars ; Physical Phenomena ; Physics ; Publishing ; *Science ; Security Measures
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-12-18
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉New York, N.Y. -- Science. 2004 Dec 17;306(5704):2013-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15604368" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biodiversity ; Biological Evolution ; Cloning, Organism ; DNA, Intergenic ; Genome ; Hominidae/anatomy & histology ; Humans ; Physical Phenomena ; Physics ; Public Health ; *Science ; Water/chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-08-03
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cho, Adrian -- New York, N.Y. -- Science. 2004 Jul 30;305(5684):643-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15286364" target="_blank"〉PubMed〈/a〉
    Keywords: *Biomechanical Phenomena ; *Engineering ; History, 20th Century ; History, 21st Century ; Humans ; Mathematics ; Mechanics ; Physics ; Research Support as Topic ; *Sports ; *Sports Equipment ; United States
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-05-29
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malakoff, David -- New York, N.Y. -- Science. 2004 May 28;304(5675):1281.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15166361" target="_blank"〉PubMed〈/a〉
    Keywords: Career Choice ; Emigration and Immigration ; History, 20th Century ; History, 21st Century ; India ; Physics ; Public Health ; United States
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-10-09
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Buskirk, Steven -- New York, N.Y. -- Science. 2004 Oct 8;306(5694):238-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA. marten@uwyo.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15472068" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Body Constitution ; Body Weight ; *Ecosystem ; Energy Metabolism ; Environment ; *Homing Behavior ; *Mammals/anatomy & histology/metabolism ; Mathematics ; *Models, Biological ; Physical Phenomena ; Physics ; Population Density
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 8
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-01-01
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉New York, N.Y. -- Science. 2003 Dec 19;302(5653):2039-45.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14700029" target="_blank"〉PubMed〈/a〉
    Keywords: Angiogenesis Inhibitors/therapeutic use ; Animals ; Astronomical Phenomena ; Astronomy ; Climate ; Germ Cells/cytology/physiology ; Humans ; Mental Disorders/etiology/genetics ; Neoplasms/blood supply/drug therapy ; Physical Phenomena ; Physics ; RNA, Antisense ; *Science/trends ; Stem Cells/physiology ; Y Chromosome/genetics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 9
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    In:  In: Klimastatusbericht 2003, DWD, Offenbach, 152-162
    Publication Date: 2003
    Keywords: Deutschland ; 2003 ; Umweltmedizin ; Temperatur
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  • 10
    Publication Date: 2003
    Description: Erfassung aller tatsächlichen oder vermuteten vektorassoziierten Krankheiten und Vektoren KATASTER-BESCHREIBUNG: viele Pathogene in Deutschland bereits vorhanden bzw. geeignete Vektoren stehen zur Verfügung, bei Einschleppung durch Reservoirwirte oder erkrankte Reisende sind autochthone Fälle zu erwarten KATASTER-DETAIL:
    Keywords: Deutschland ; Umweltmedizin ; Infektionskrankheiten
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  • 11
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-07-12
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vogel, Gretchen -- New York, N.Y. -- Science. 2003 Jul 11;301(5630):150.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12855778" target="_blank"〉PubMed〈/a〉
    Keywords: *Biomedical Research ; Germany ; Neurosciences ; Physical Phenomena ; Physics ; Publishing ; Research/*standards ; Research Support as Topic ; *Scientific Misconduct
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 12
    Publication Date: 2003-11-15
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malakoff, David -- Cho, Adrian -- New York, N.Y. -- Science. 2003 Nov 14;302(5648):1126-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14615496" target="_blank"〉PubMed〈/a〉
    Keywords: Computers ; Facility Design and Construction ; Financing, Government ; Molecular Biology ; Nuclear Reactors ; Physical Phenomena ; Physics ; *Research Support as Topic ; United States ; *United States Government Agencies
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 13
    Publication Date: 2003-04-19
    Description: Using three-dimensional infrared high-speed video, we captured the wing and body kinematics of free-flying fruit flies as they performed rapid flight maneuvers. We then "replayed" the wing kinematics on a dynamically scaled robotic model to measure the aerodynamic forces produced by the wings. The results show that a fly generates rapid turns with surprisingly subtle modifications in wing motion, which nonetheless generate sufficient torque for the fly to rotate its body through each turn. The magnitude and time course of the torque and body motion during rapid turns indicate that inertia, not friction, dominates the flight dynamics of insects.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fry, Steven N -- Sayaman, Rosalyn -- Dickinson, Michael H -- New York, N.Y. -- Science. 2003 Apr 18;300(5618):495-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Neuroinformatics, University/ETH Zurich, Winterthurerstr. 190, CH-8057 Zurich, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12702878" target="_blank"〉PubMed〈/a〉
    Keywords: Acceleration ; Animals ; Biomechanical Phenomena ; Body Constitution ; Drosophila melanogaster/anatomy & histology/*physiology ; Flight, Animal/*physiology ; Friction ; Mathematics ; Motion ; Movement ; Physical Phenomena ; Physics ; Robotics ; Rotation ; Torque ; Video Recording ; Wings, Animal/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 14
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-07-26
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Couzin, Jennifer -- New York, N.Y. -- Science. 2003 Jul 25;301(5632):444.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12881536" target="_blank"〉PubMed〈/a〉
    Keywords: *Biological Science Disciplines ; Budgets ; Financing, Government ; *National Institutes of Health (U.S.) ; *Natural Science Disciplines ; Physical Phenomena ; Physics ; *Research Support as Topic ; United States
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 15
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    In:  J. Geophys. Res., Amsterdam, Schweizerbart'sche Verlagsbuchhandlung, vol. 107, no. B10, pp. ECV 6-1-ECV 6-17, pp. 2223, (ISSN 0016-8548, ISBN 3-510-50045-8)
    Publication Date: 2002
    Description: We use laboratory experiments and numerical models to quantify the effects of dike interaction on the focusing of magma as it ascends in the upper mantle. Laboratory experiments involve injecting buoyant fluid into the base of a tank filled with solidified gelatin. When we initiate two dikes parallel to each other, but separated by a horizontal distance x, they tend to merge as they ascend. This behavior is also predicted by numerical models of two-dimensional dikes. The key parameters that control the maximum horizontal separation x c over which dikes will intersect are dike driving pressures, dike head lengths L (i.e., the length over which driving pressure is large), and the difference between the principal stresses of the remote stress field. When the remote differential stress is small compared to the dike driving pressure, two dikes of equal driving pressure and length will intersect over distances of x c ? L. This distance decreases with increasing remote differential stress. We quantify the effects on magma transport from a broad lateral distribution of magma using numerical simulations of multiple-dike interaction. When the average dike spacing prior to interaction is within ?3 L and remote differential stresses are insignificant, dike interaction can focus magma over horizontal distances many times L but at least ?6 L. Dike interaction can focus magma in the asthenosphere beneath mid-ocean ridges for low mantle viscosities (?10 19 Pa s) and if dikes initiate with average separations of a few hundred meters, or less. Such focusing is predicted to grow dikes of increasing magma flux approaching lateral separations of a kilometer.
    Keywords: Fluids ; Plate tectonics ; ascent ; sheeted ; dykes ; Modelling ; JGR ; 8434 ; Volcanology: ; Magma ; migration ; 8145 ; Tectonophysics: ; Physics ; of ; magma ; and ; magma ; bodies ; 8120 ; Dynamics ; of ; lithosphere ; and ; mantle--general ; 3035 ; Marine ; Geology ; and ; Geophysics: ; Midocean ; ridge ; processes
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  • 16
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2002-10-09
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Radny, Marian W -- New York, N.Y. -- Science. 2002 Oct 4;298(5591):59; author reply 59.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12365438" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Body Constitution ; Body Weight ; *Carnivora/anatomy & histology/metabolism ; *Ecosystem ; *Food ; Physical Phenomena ; Physics ; Population Density
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 17
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2002-03-30
    Description: Beyond molecular chemistry based on the covalent bond, supramolecular chemistry aims at developing highly complex chemical systems from components interacting through noncovalent intermolecular forces. Over the past quarter century, supramolecular chemistry has grown into a major field and has fueled numerous developments at the interfaces with biology and physics. Some of the conceptual advances and future challenges are profiled here.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lehn, Jean-Marie -- New York, N.Y. -- Science. 2002 Mar 29;295(5564):2400-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut de Science et d'Ingenierie Supramoleculaires (ISIS), Universite Louis Pasteur, 67000 Strasbourg, and College de France, 75005 Paris, France. lehn@chimie.u-strasbg.fr〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11923524" target="_blank"〉PubMed〈/a〉
    Keywords: Biology ; Chemical Phenomena ; *Chemistry ; Chemistry, Physical ; Molecular Structure ; Nanotechnology ; Physical Phenomena ; Physicochemical Phenomena ; Physics ; *Polymers/chemistry
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    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 18
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    In:  Beiträge für Forstwirtschaft und Landschaftsökologie 2001(4): 4
    Publication Date: 2001
    Description: deutliche Verschiebungen der phänologischen Jahreszeiten, besonders der Frühjahrsphasen; für jede phänologische Phase negative und auch positive Trends entdeckt, z.T. auf engen Raum; Verschiebung auf Variation der Lufttemperatur zurückzuführen; Verlängerung der Vegetationsperiode, hauptsächlich durch Veränderungen im Frühjahr KATASTER-BESCHREIBUNG: KATASTER-DETAIL:
    Keywords: Deutschland ; 1951-1996
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  • 19
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2001-06-09
    Description: A free-electron laser consists of an electron beam propagating through a periodic magnetic field. Today such lasers are used for research in materials science, chemical technology, biophysical science, medical applications, surface studies, and solid-state physics. Free-electron lasers with higher average power and shorter wavelengths are under development. Future applications range from industrial processing of materials to light sources for soft and hard x-rays.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉O'Shea, P G -- Freund, H P -- New York, N.Y. -- Science. 2001 Jun 8;292(5523):1853-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Electrical and Computer Engineering and Institute for Plasma Research, University of Maryland, College Park, MD 20742, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11397938" target="_blank"〉PubMed〈/a〉
    Keywords: Biochemical Phenomena ; Biochemistry ; Biological Science Disciplines ; Electromagnetic Fields ; Electrons ; Laser Therapy ; *Lasers ; Physical Phenomena ; Physics ; *Research
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 20
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2001-12-26
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉New York, N.Y. -- Science. 2001 Dec 21;294(5551):2443-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11752538" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antineoplastic Agents/therapeutic use ; Axons/physiology ; Benzamides ; Carbon ; Climate ; Ecosystem ; Electronics ; Genome, Human ; Humans ; Imatinib Mesylate ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy ; Physical Phenomena ; Physics ; Piperazines/therapeutic use ; Pyrimidines/therapeutic use ; Rna ; *Research ; *Science
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 21
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2001-06-16
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malakoff, D -- New York, N.Y. -- Science. 2001 Jun 15;292(5524):1979.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11408626" target="_blank"〉PubMed〈/a〉
    Keywords: *Bacterial Physiological Phenomena ; Financing, Government ; Geological Phenomena ; Geology ; Gold ; *Laboratories ; *Mining ; *Natural Science Disciplines ; Physical Phenomena ; Physics ; Research ; United States
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 22
    Publication Date: 2001-09-15
    Description: Recent advances in machine learning methods, along with successful applications across a wide variety of fields such as planetary science and bioinformatics, promise powerful new tools for practicing scientists. This viewpoint highlights some useful characteristics of modern machine learning methods and their relevance to scientific applications. We conclude with some speculations on near-term progress and promising directions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mjolsness, E -- DeCoste, D -- New York, N.Y. -- Science. 2001 Sep 14;293(5537):2051-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Machine Learning Systems Group, Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA, 91109, USA. mjolsness@jpl.nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11557883" target="_blank"〉PubMed〈/a〉
    Keywords: Algorithms ; Animals ; *Artificial Intelligence ; Astronomical Phenomena ; Astronomy ; Cluster Analysis ; *Computational Biology ; Computer Simulation ; Gene Expression Profiling ; Gene Expression Regulation ; Image Processing, Computer-Assisted ; Neural Networks (Computer) ; Physical Phenomena ; Physics ; Robotics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 23
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    In:  J. Geophys. Res., Hannover, Dt. Geophys. Ges. e. V., vol. 105, no. B4, pp. 8103-8120, pp. 1058, (ISSN: 1340-4202)
    Publication Date: 2000
    Keywords: Crustal deformation (cf. Earthquake precursor: deformation or strain) ; InSAR ; Geodesy ; Modelling ; JGR ; 1243 ; Geodesy ; and ; gravity ; Space ; geodetic ; surveys ; 3210 ; Mathematical ; geophysics ; (new ; field) ; Modeling ; 8145 ; Tectonophysics ; Physics ; of ; magma ; and ; magma ; bodies ; 8499 ; Volcanology
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  • 24
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2000-06-08
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Normile, D -- New York, N.Y. -- Science. 2000 May 19;288(5469):1165.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10841732" target="_blank"〉PubMed〈/a〉
    Keywords: *Academies and Institutes/economics ; Animals ; Astronomical Phenomena ; Astronomy ; Chloroplasts/genetics ; Drosophila/genetics ; Interferometry ; *Molecular Biology/economics ; Physical Phenomena ; Physics ; *Research/economics ; Research Support as Topic ; Taiwan
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 25
    Unknown
    Amsterdam ; New York : Elsevier
    Keywords: DDC 511.3 ; LC QA9.9 ; Brain - Mathematical models ; Cognition ; Cognition - Mathematical models ; Matrix logic ; Models, Theoretical ; Physics ; Quantum theory
    Pages: Online-Ressource (xii, 588 pages)
    ISBN: 9780444826183
    Language: English
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  • 26
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 1-23 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new calculation of the vibrational frequencies of poly(ethy1 ethylene) based on the actual molecular geometry was performed. The calculation takes into account new experimental data such far-infrared spectra and Raman spectra of the stretched polymer, infrared spectra of poly(ethyl ethylene)-(2,2;d2) (P-4-1-d2) and poly(ethyl ethylene)-(3,3,4,4;d4) (P-4-1-d4), and Raman spectra of poly(ethyl ethylene)-(1,3,3;d3) and poly(ethyl ethylene)-(3,3,4,4;d4). Refinement produced a set of force constants; it is also applicable to poly(propyl ethylene).
    Additional Material: 4 Ill.
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  • 27
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The vibrational analysis of modification I of poly(propyl ethylene), poly(propyl ethylene)-(2,2;d2), and poly(propyl ethylene)-(1,2,2;d3) has been performed using the valence force field derived for poly(ethyl ethylene) and the actual molecular geometry. The band assignments are based on infrared polarization and Raman data.
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  • 28
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    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 55-62 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The nucleation and growth of the crystalline core in the row structures of isotactic polystyrene were investigated by transmission electron microscopy. The number of core crystals, nucleated at a specific temperature, depends on the external strain. Their length was found to increase with time if the sample is kept at the straining temperature. If a strained sample is cooled to room temperature and subsequently reheated, no further growth of the core crystals is observed. Obstacles in the path of growth were circumvented by local changes of the growing direction. Melt-soluble noncrystallizable molecules are rejected by the growing core into the surrounding melt. The observations suggest a growth mechanism of the cores based on the successive self-induced alignment of molecules at the tip of the growing cores.
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  • 29
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    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 45-53 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Carbon-13 spin-lattice relaxation times (T1), nuclear Overhauser enhancements (NOE), and resonance linewidths (Δp) have been measured for a series of terephthalic acid polyesters containing ethyl, butyl, hexyl, and isopropyl groups between neighboring terephthalate units. The relaxation parameters of all carbons in the terephthalate groups are independent of the length of the separating alkyl chain. Reduced NOE's are seen for all carbons. The data are interpreted in terms of a log X2distribution of correlation times of constant width, but variable average mobility. The average mobility in the alkyl chain increases with increasing distance from the terephthalate group in a given polymer. For a given position in the chain. mobility increases with increasing chain length. This behavior is consistent with the presence of independently reorienting, highly solvated terephthalate groups.
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  • 30
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    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 73-79 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polytetrafluoroethylene (PTFE) was extruded from a capillary rheometer at temperatures between the first-order transition at 30°C and the melting point. Both PTFE at 50-300°C and various smectic states of certain low-molecular benzylidene anilines obey the following relationship between the shear stress τ and the apparent shear rate $ \dot \gamma :{\rm }\tau = K\dot \gamma ^{{1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4}} $. The apparent viscosities for the two classes of substances are similar even though their molecular weights differ by a factor of about 104. Both have characteristic shear planes which are parallel to the polymer chains in PTFE and normal to the long axes of the benzylidene aniline molecules. The melting process in virgin PTFE begins near 300°C. Above this temperature, the shear stress at constant shear rate increases and the rheological exponent rises from 0.25 toward 0.5 at the final melting point.
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  • 31
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    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 63-71 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Recent experiments have supported the view that polyethylene (PE) single crystals kept in suspension, in a variety of liquids, have different physical properties compared with the same crystals after drying. The present work was undertaken in an attempt to directly measure one of the basic properties of crystals in suspension, namely their percent crystallinity (X). Differential scanning calorimetry was chosen as the primary tool for this investigation. A method has been developed to determine the weight of PE in a suspension of crystals in a nonsolvent. Thus, a determination of X can be made. For suspension crystals, X was found to be at least 88.5%, some 6% larger than that for the corresponding dried or freeze-dried material. Implications with regard to the fold-surface structure are discussed. Differences in degree of crystallinity as a function of drying procedure have also been observed.
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  • 32
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 19-26 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of methyl methacrylate photosensitized by several alkyl ketones has been investigated. It was found that alkyl ketones can induce the free radical polymerization of the monomer with an efficiency that increases when the triplet lifetime decreases. For ketones of similar triplet lifetime those decomposing predominantly by a type I photocleavage show greater initiation efficiencies than those that react by a type II mechanism. The results obtained show that quenching of the excited ketones by the monomer does not induce polymerization. For ketones bearing γ-hydrogens the initiation is due to the 1,4-biradical produced by intramolecular hydrogen abstraction.
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  • 33
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 49-58 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of γ irradiation on a series of vinyl polymers, which included polymethacrylonitrile, poly(α-chloroacrylonitrile), poly(dimethyl itaconate), poly(acrylic anhydride), and poly(methacrylic anhydride), was studied as part of a program to develop improved positive lithographic resists. Radiation-induced degradation was observed for polymethacrylonitrile, poly(α-chloroacrylonitrile), and poly(methacrylic anhydride). Molecular weight degradation as a function of dose was monitored by membrane osmometry or GPC techniques. For γ-irradiated poly(dimethyl itaconate) and poly(acrylic anhydride) crosslinking was found to predominate over chain scission. [G(s)-G(x)] values, calculated from molecular weight inverse versus dose curves, indicate that both nitrile polymers degraded more efficiently than a poly(methyl methacrylate) reference standard on the basis of Mn changes. The radiation behavior of the first three polymers confirms earlier findings than vinyl polymers with quaternary carbons predominantly degrade when subjected to ionizing radiation.
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  • 34
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 97-109 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The triethylamine-initiated polymerization of glycine-NCA [N-carboxylic acid anhydrides (oxazolidine-2,5-diones)], L-alanine-NCA, and sarcosine-NCA, as well as the pyridine-initiated polymerization of sarcosine-NCA, were carried out in the presence of potential cocatalysts. The 11 electrophilic reagents tested in this work can be divided into two classes: N-acyllactams and similar compounds, which are less reactive than the monomers and have no influence on the polymerization; and isocyanates and N-acyl-NCAs or -NTAs [N-thiocarboxylic acid anhydrides (thiazolldine-2,5-diones)], which are more electrophilic than the monomers and behave as cocatalysts in the case of glycine-NCA and alanine-NCA, since their base-initiated polymerization proceeds via the attack of NCA anions on the electrophilic N-acyl NCA chain and (“activated monomer mechanism”). In the case of sarcosine-NCA, however, the propagation involves a nucleophilic chain end (“carbamate mechanism”) and the strong electrophilic reagents behave as inhibitors.
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  • 35
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 139-145 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of poly(vinyl chloride) (PVC) with superoxide anion was carried out in tetrahydrofuran (THF) at 40°C in a nitrogen atmosphere. Remarkable changes in infrared (IR) spectra of the samples treated with superoxide anion were observed in the following regions: ca. 3300, 1680, 1620, and 765 cm-1, which suggested the formation of hydroxyl groups, α,β-unsaturated ketone groups, and ethylenic structures. Ultraviolet-visible spectra also showed the formation of polyene structures. The content of chlorine in the polymer decreased and that of oxygen increased with reaction time. The reaction mechanism was discussed on the basis of these results.
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  • 36
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 155-162 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To determine the content of trans-gauche-trans (TGT) conformation in poly(ethylene glycol) (PEG) 1H-NMR spectra were measured with tris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-1,4,6-octanedinato)europium(III) [Eu(fod)3] as a shift reagent. As a result the peaks assigned to the ethylene protons in the polymeric segments separated from those assigned to four ethylene protons as the “near-end” groups, and the singlet peak in the former at the lowest field was assigned to the TGT conformation of the COCCOC sequence. It was confirmed that the conformation of the polymeric segments in PEG complexed with Eu(fod)3 remained unchanged with benzene-d6 content as the solvent. The concentration of TGT conformation increased with the number-average molecular weight (Mn): it increased rapidly until about 70% at Mn = 1500.
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  • 37
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 173-184 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: γ-Ray-induced polymerizations of ferrocenylmethyl methacrylate (FMMA) in crystalline and amorphous states were investigated with kinetical and ESR methods. In the crystalline state the polymerization of FMMA proceeded slowly and gave low-molecular-weight polymers, whereas in the amorphous state it proceeded rapidly and gave polymers of much higher molecular weight. Molecular weight distributions of these polymers were binodal. The temperature dependence and the dose-rate dependence of the polymerization rates were different between the two states. Wide-line nuclear magnetic resonance (NMR) spectra of the amorphous monomer suggested that the polymerization proceeded in a supercooled state. Electron spin resonance (ESR) spectra of γ-irradiated FMMA and 1,1′-ferrocenyl-di(methyl methacrylate) showed that ferrocene radicals and methacrylic radicals were formed simultaneously at low temperature; with increasing temperature the former radicals disappeared, whereas the latter changed into growing chain radicals. The yields of radicals were relatively low; this means that ferrocene groups in the monomers behave as a radiation energy absorber.
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  • 38
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 215-224 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It was found that carbon disulfide copolymerizes with N-(β-cyanoethyl) ethylenimine by using water as a catalyst. The copolymerization was conducted in detail by using water as a catalyst in the temperature range between 0 and 50°C with various initial concentrations of carbon disulfide and N-(β-cyanoethyl)ethylenimine in the absence of solvent. The copolymer obtained was always composed of the two monomers: 1:1 ratio, independent of the initial concentration of the monomers. The copolymer was white solid material soluble in dimethyl sulfoxide, insoluble in other usual organic solvents and decomposed at 155°C. Spectroscopic analysis of the copolymer combined with the results of elemental analysis indicates that the copolymer had the following structure:
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  • 39
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 267-269 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 40
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 255-266 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alternating polyampholytes (MA-VA) containing two acidic groups and one basic group were prepared by the copolymerization of maleic anhydride (M1) and N-vinylsuccinimide (M2) at 60°C with AIBN as the initiator, followed by acid hydrolysis with 1N hydrochloric acid at 140°C for 24 hr. The monomer reactivity ratios r1 and r2 are 0.025 and 0.06, respectively. The structure of polymers was discussed on the basis of the data of their elementary, infrared (IR), and thermal analyses and the binding ability of heavy metal ion. Polyampholytes were soluble in strong acidic and basic media but were precipitated in the pH range 3-4. An isoelectric point at pH 3 was determined by potentiometric titration and the turbidimetric method. By thermal treatment above 205°C the polyampholyte turned quantitatively into a cyclized lactam. This suggests that the polyampholyte MA-VA has an intramolecular hydrogen bond between the amino and γ-carboxyl groups. The binding of Cu2+ and Hg2+ by the polyelectrolyte was evaluated by equilibrium dialysis.
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  • 41
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 203-213 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Detailed results of the overall thermal degradation of poly(butylene terephthalate) are reported. Laser microprobe analysis and dynamic mass spectrometric techniques were used to identify the primary volatile degradation products and initial pyrolysis reactions that control polymer degradation. A complex multistage decomposition mechanism was observed which involves two major reaction pathways. Initial degradation occurs by an ionic decomposition process that results in the evolution of tetrahydrofuran. This is followed by concerted ester pyrolysis reactions that involve an intermediate cyclic transition state and yield 1,3-butadiene. Simultaneous decarboxylation reactions occur in both decomposition regimes. Finally, the latter stages of polymer decomposition were characterized by evolution of CO and complex aromatic species such as toluene, benzoic acid, and terephthalic acid. Activation energies of formation for the main pyrolysis products were determined from the dynamic measurements of the major ion species and indicate values of E = 27.9 kcal/mole for the production of tetrahydrofuran and E = 49.7 kcal/mole for the production of butadiene.
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  • 42
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 225-236 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article deals with studies of the dilute solution properties of methyl methacrylate-acrylonitrile (MMA-AN) copolymer of 0.415 mole fraction (mf) of acrylonitrile composition. Mark - Houwink parameters for this copolymer have been evaluated in acetonitrile (MeCN), 2-butanone (MEK), dimethyl formamide (DMF), and γ-butyrolactone (γ-BL). The Mark-Houwink exponent a in all four solvents at all temperatures is larger than the corresponding values of the parent homopolymers. The solvent power is in the order of DMF 〈 γ-BL 〈 MEK 〈 MeCN; [η] decreases with an increase in temperature, which is behavior characteristic of polymers in good solvent. The unperturbed dimensions (K0) values, obtained by the Stockmayer-Fixman method, are lower than those for the parent homopolymers and depend on solvent as well as temperature. The solute - solvent interaction parameter X1 values are close to 0.5; X1 is independent of temperature. The excess interaction parameter XABvalues are negative. The results for this copolymer system in regard to low second virial coefficient A2, large X1, and high a values suggest that the large extension of these copolymer chains is due to the unusual short-range interactions.
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  • 43
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 245-254 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (2-Ethyl-2-methyl-1,3-dioxolan-4-yl)methyl- and (2-methyl-2-phenyl-1,3-dioxolan-4-yl) methyl acrylates were synthesized and polymerized. The photochemical behavior of the resulting polymers was investigated to determine whether the polymers pending on the 1,3-dioxolane structure were readily crosslinked with ultraviolet (UV) irradiation. The degree of crosslinking was estimated by the weight-loss method by immersion in acetone, with the result that the polymer with an aromatic substituent was more photocrosslinkable than the polymer that bore the aliphatic substituent. The catalytic effect on photocrosslinking of polymers was also studied by using benzoin and cobalt naphthenate. The infrared (IR) spectra of polymers irradiated in air that showed the new band at 3450 cm-1 were attributed to a hydroxyl group; however, the spectra of polymers irradiated in vacuum displayed little absorption at 3450 cm-1. To explain the mechanism of crosslinking model compounds were prepared and irradiated with UV light. It was concluded that crosslinking proceeds mainly from the fission of the 1,3-dioxolane ring and the coupling of the yielding radicals, together with autooxidation by atmospheric oxygen.
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  • 44
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 281-286 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 45
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 301-312 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Behavior of the free radical copolymerization of N-β-methacryloyloxyethyl derivatives of adenine with that of thymine was studied in chloroform solution, taking account of the specific base-base interaction of these monomers. Hydrogen bonding interaction between such monomers was observed by NMR spectroscopy. The acceleration of copolymerization was found to be greater either at lower monomer concentration or at lower polymerization temperature. When N-β-methacryloyloxyethylcarbazole was used as a comonomer, the rate of copolymerization showed a similar trend as in the case of usual free radical copolymerizations. From r1 and r2 values obtained, the copolymerization was found to be alternating, particularly in the case of copolymerization between monomers having complementary nucleic acid bases. The results suggest that the hydrogen bonding interaction between adenine and thymine plays a role in the propagation step.
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  • 46
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 385-392 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Benzaldehyde (PhCHO) is found to be able to initiate the radical polymerization of methyl methacrylate (MMA). The rate of polymerization is expressed by the following equation: Rp = const[PhCHO]0.5[MMA]1.5. The overall activation energy is estimated to be 56.3 kJ mole-1. The mechanism of polymerization is discussed.
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  • 47
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 351-363 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: “Pyran” copolymer, the 2:1 regularly alternating cyclocopolymer (DVE - MA) of maleic anhydride (MA) and divinyl ether (DVE), first discovered in 1951, has been investigated extensively, both from the standpoint of its chemical structure and its biological activity. Although certain aspects of its structure remain to be determined, it has been shown to possess a wide spectrum of biological activity. It possesses antitumor activity and has been investigated clinically. During the clinical investigation, it was found to be an interferon inducer. Interferon is a protein which appears to be the body's first line of defense against viral infection. DVE - MA also possesses antiviral, antibacterial, antifungal, antiarthritic, and anticoagulant properties, activates macrophages, inhibits reverse transcriptase, and is capable of elimination of Pu. During the course of investigations in these laboratories, many structural modifications of DVE - MA have been made. Many of these modifications also possess considerable antitumor activity and interferon-induction capability. Perhaps the most interesting structural modification has been the incorporation of 5-fluorouracil (5-FU) into the polymer (NSC 255083). This polymer has shown (T/C)% [= ratio of test (T) to control (C) survival times] = 189 for dose by intraperitoneal injection of 200 mg/kg animal weight in CD2F1 mice (6/6 survivors after fifth day) against P388 lymphocytic leukemia. This article describes the synthesis of both the monomer and copolymer, and a study of the hydrolytic rate of release of 5-FU from the polymer.
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  • 48
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 377-384 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,2,4-Trimethyl-3-on-1-pentyl methacrylate (TMPM) was first synthesized from the condensation reaction of 2,2,4-trimethyl-1-pentanol-3-on with methacrylic acid. Second, the polymerization of TMPM and the copolymerization of TMPM with styrene (St) were carried out in benzene at 60°C, using 2,2′-azobisisobutyronitrile (AIBN) as an initiator. As the result of kinetic investigation, the rate of polymerization (Rp) could be expressed by: Rp = k[AIBN]0.5 [TMPM]1.0. Kinetic constants of polymerization of TMPM were obtained as follows: kp/kt1/2 = 0.27 dm3/2 mole-1/2 sec-1/2, 2fkd = 1.23 × 10-5 sec-1, f = 0.73, Cm = 2.6 × 10-5, Cs = 1.1 × 10-5. From the results the reactivity of TMPM was found to be larger than that of methyl methacrylate. The overall activation energy was calculated to be 110 kJ mole-1. The following monomer reactivity ratios and Q, e values were obtained: TMPM(M1) - St(M2): r1 = 1.50, r2 = 0.14, Q1 = 2.63, E1 = 0.45.
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  • 49
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 415-423 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The homopolymerization of propylene oxide was first conducted at 80°C in the absence of any solvent by using various metal salts of acetic acid and it was found that Mg(OAc)2, Cr(OAc)3, Mn(OAc)2, Co(OAc)2, Ni(OAc)2, Zn(OAc)2, and Sn(OAc)2 were effective for the polymerization. The copolymerization of propylene oxide and carbon dioxide was next examined by using these effective metal salts of acetic acid as catalysts. Most of these were effective also for the copolymerization. The nature of the polymer obtained was strongly dependent on the catalyst used. Co(OAc)2 and Zn(OAc)2 gave an alternate copolymer of propylene oxide and carbon dioxide, Mg(OAc)2, Cr(OAc)3, and Ni(OAc)2 gave a random copolymer, while Sn(OAc)2 gave a homopolymer of propylene oxide. Then the copolymerization of propylene oxide and carbon dioxide was kinetically investigated in some detail by using Co(OAc)2 as a catalyst. On the basis of the results obtained, a plausible mechanism was proposed for both the homopolymerization of propylene oxide and copolymerization of propylene oxide and carbon dioxide.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 455-464 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the intermediates in unterminated polymerization reactions were studied. It was found that in a first-order initiation (A) all intermediates accumulate monotonically. In a second-order initiation (B) the first intermediates pass through a maximum, whereas the later ones strictly accumulate. An initiator-started polymerization can follow course A or course B, depending on the initial ratio of the concentrations of the initiator and monomer.
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  • 51
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 473-484 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The copolymerizations of l-menthyl vinyl ether (l-MVE) with the monomers, that is, maleic anhydride (MAn), dimethyl maleate (DMM), and dimethyl fumarate (DMFu), were undertaken to obtain optically active copolymers. The optically active l-menthyl group in the side chain of copolymers was removed by the ether cleavage reaction with dry-hydrogen bromide gas. The ethercloven copolymers were still optically active. Hence it was concluded that asymmetric carbon atoms were introduced into the copolymer main chain, the reason given being that l-MVE and comonomers (MAn, DMM, and DMFu) made the stereoselective charge-transfer complex one another and copolymerized stereospecifically. From the results of the measurements of optical rotatory dispersion (ORD) and circular dichroism (CD) for copolymers before and after the ether cleavage reaction, the mode of bond opening for α,β-substituted monomers (MAn, DMM, and DMFu) was discussed and the microstructures of copolymers were prepared.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 503-516 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stability of PTFE latex prepared in the absence of emulsifier by radiation-induced polymerization was investigated by electrophoresis and conductometric titration. The storage stability depends on total dose rather than dose rate, and the stable latex can be obtained in the region log D 〉 0.026 V1 - 0.6, where D is the total dose (104 rad) and V1 is a polymer concentration in latex (g/liter). The stability increases only during polymerization in the presence of enough TFE monomer. The ζ potential of the latex particles lies in the region from -25 to -50 mV in an as-polymerized state (near pH 3) and from -50 to -65 mV at pH 10. The number of carboxyl end groups and surface charge density were examined by conductometric titration with NaOH and calculation from the G values of radiolysis of water. All the surface charge densities measured by conductometric titration are larger than those calculated from the G values. These results suggest that some acids have been formed on the surface of the particles. The acids may be the carboxyl end groups of polymer chains or hydrofluoric acid (HF) adsorbed on the surface. PTFE particles prepared in this polymerization system are stabilized mainly due to the carboxyl end groups and adsorptions of OH- and HF on the particles.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 539-550 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermodynamically effective fixed-charge density of mercuric phosphate and carbonate parchment-supported membranes have been evaluated by the most recent method of Nagasawa et al., based on the thermodynamics of irreversible processes and compared with the values obtained by the Kobatake et al. and Teorell - Meyer - Sievers (TMS) methods. Bi-ionic potential (BIP) has also been measured for these membranes with three pairs of electrolyte solutions: KCl—NaCl, KCl—LiCl, and NaCl—LiCl. Theoretical values of BIP have been calculated by using the membrane potential and BIP theories recently developed by Toyoshima et al., based on nonequilibrium thermodynamics. Various parameters have also been evaluated and it was found that the theoretical equation of BIP is applicable to these parchment-supported membranes.
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  • 54
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 571-582 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new techniques for the determination of monomer reactivity ratios in copolymerization under high-pressure conditions have been developed, viz., the “sandwich” and the “quenching” method. Both methods are based on repeated quantitative gas chromatographic analysis of the reaction mixture during the low-pressure stages preceding and succeeding the high-pressure stage, of which the kinetics is under investigation. Application of the “sandwich” method implies the occurrence of reaction during both low-pressure stages and consequently the low-pressure kinetic data are required to obtain the transition points of low to high pressure and vice versa. These points constitute the initial and final conditions of the relevant high-pressure reaction. On the contrary, in the “quenching” method no reaction occurs during the low-pressure stages, owing to the lower temperature and the high activation energy of the initiator decomposition. As a consequence, the initial and final conditions of the high-pressure stage can be determined by a simple averaging procedure. Both methods have been tested for the ethylene - vinyl acetate copolymerization at 62°C and 600 kg/cm2 with tert-butyl alcohol as solvent, and appear to lead to almost identical monomer reactivity ratios, although the “quenching” method is slightly preferred in case of copolymerization reactions. Both methods are particularly valuable when one of the reactants is gaseous or the reaction produces a gas. Further merits and drawbacks of both methods are discussed.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 613-616 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 747-757 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In due consideration of the specific base-base interaction that exists between nucleic acid molecules, the free radical polymerization of N-β-methacryloyloxyethyl derivatives of adenine, thymine, and theophylline initiated by azobisisobutyronitrile (AIBN) was studied in the presence of N-β-methacryloyloxyethyl-type polymers which have complementary nucleic acid bases as template polymers. The rate of polymerization of N-β-methacryloyloxyethyladenine was accelerated when poly(N-β-methacryloyloxyethyluracil) or -thymine was present in the polymerization system. The effect of the stereoregularity of the template polymers, as well as polymerization temperature and the sort of solvents used on the rate of polymerization, was studied and discussed in some detail. The results suggest that the interaction between complementary bases plays a role in template polymerization behavior.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 783-787 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
    Notes: Catalytic actions of various additives were studied in the polycondensation of di(4-nitrophenyl) isophthalate with bis(4-aminophenyl) ether in N-methyl-2-pyrrolidone, and 1-hydroxybenzotriazole (HOBt) was found to be a highly effective catalyst that yielded high-molecular-weight polyamide. In addition to the polycondensation of the 4-nitrophenyl ester, the polymerization of negatively substituted phenyl esters like di(2,4,5-trichlorophenyl) isophthalate was also accelerated by HOBt. For the HOBt-catalyzed aminolysis of esters a bifunctional concerted mechanism that involves an eight-membered transition state was proposed.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 807-813 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
    Notes: The equilibrium constants of the coordination reaction of chlorodimethylformamide·cobaloxime with 4-vinylpyridine-styrene copolymers (PPS) were determined. The constants for PPS, which contain 20-50% 4-vinylpyridine (4VP) unit, measured about 1.3 × 105 liter/mole larger than those in the pyridine system (6.8 × 104 liter/mole). When the polymer ligand is 4VP homopolymer or contains less than 20% 4VP unit, K values are lower. The rate constants (kf) of the coordination reactions of the cobaloxime with polymer ligands were also measured in dimethylformamide (DMF) and benzene. In DMF kf decreased with an increase in 4VP unit content of the polymer ligand; in benzene it was increased by the 4VP fraction. These results can be explained by the variation in conformation of the polymer chain in each solvent. The effect of the polymer chain on complexation was discussed on the basis of the kinetic data.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 877-888 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of the 1:2 copolymer of divinyl ether and maleic anhydride was investigated by 13C-NMR spectroscopy. The polymer contains the bicyclic unit composed of one molecule of each monomer and the maleic anhydride unit. The carbon chemical shift for these units was calculated on the basis of the chemical shift of many model compounds. The major peaks of the cyclopolymer prepared in chloroform were consistent with the presence of the symmetrical bicyclic unit with cis junction and the trans monocyclic anhydride unit. The carbonyl carbon spectrum for the copolymer obtained in a mixed solvent of acetone and CS2 suggested the predominant formation of the unsymmetrical bicyclic unit. The polymerization process was discussed on the basis of these results.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 917-918 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 905-916 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
    Notes: The complex formation between a poly(N-β-methacryloyloxyethyl) derivative of adenine with one of thymine or uracil was studied in dimethyl sulfoxide and ethylene glycol mixture by ultraviolet (UV) spectroscopy. For the polymer pairs containing complementary nucleic acid bases both hypochromicity and hyperchromicity were found. Stereoregularity of the polymers, as well as the conditions for measurement of, for example, solvent, temperature, and time, affected the complex formation. Both inter- and intramolecular interaction of polymers in solution were discussed in some detail.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 923-926 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 931-934 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
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    Notes: Methyl methacrylate (MMA) and styrene (St) copolymerize in the presence of zinc chloride at 3°C under photoirradiation. The contents of methyl methacrylate in the copolymers obtained at a [ZnCl2]/[MMA] molar ratio of 0.4 are systematically larger than 53 mole %, which is the limiting value at a small feed ratio of methyl methacrylate. The resulting copolymers are confirmed as the sole products and not the mixtures by thin layer chromatography. The effect of dilution of the monomer feed mixture with toluene on copolymer composition suggests that it depends chiefly on the feed concentration of styrene and hardly at all on monomer feed ratios. Copolymerizations are also conducted in the presence of stannic chloride at -17°C under photoirradiation and in the presence of ethylaluminium sesquichloride at 0°C with spontaneous initiation. The contents of methyl methacrylate in both copolymers obtained at feed ratios lower than 60 mole % almost correspond to the 1:1 alternating copolymer and increase systematically with higher feed ratios. The systematic deviations of copolymer composition obtained in the presence of metal halides are reasonably interpreted by the participation of the binary molecular complex composed of metal halide and methyl methacrylate in the polymerization of the ternary molecular complex composed of metal halide, methyl methacrylate, and styrene.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 889-904 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
    Notes: The process of polyethylene terephthalate (PET) formation in the presence of dicarboxylic acids has been studied. Certain amounts of terephthalic acid (TPA) have two- to threefold accelerating efficiency in the polycondensation process. To elucidate the causes of the acceleration the main reactions leading to PET formation in the presence of dicarboxylic acids have been investigated by the use of models. The evaluation of kinetic and equilibrium parameters obtained for model reactions made it possible to conclude that the influence of carboxyl-containing additives on the apparent rate of polycondensation manifests itself in accelerating direct reactions and facilitating the liberation of the eliminated by-product; that is, ethylene glycol (EG) from the polymer melt. Carboxylic acid acts as a catalyst on the ester interchange of 2-hydroxyethyl ester end groups and thus increases the rate of polymer formation in this reaction 10-40 times. The parallel interaction between the 2-hydroxyethyl ester end group and the carboxyl group of the added acid is also catalyzed by the acid and its rate constant is four times larger than that of the catalytic polycondensation of 2-hydroxyethyl ester end groups. Unlike EG, the reaction water formed in the process is more readily removed from the reaction system and thus promotes the intensification of the process. In addition, the carboxyl groups react with the eliminated EG to decrease its amount and shift the equilibrium toward polymer formation. The investigation of the consequent parallel reactions on models made it possible to draw a conclusion about the higher reactivity of 2-hydroxyethyl esters in the esterification processes. This fact has been explained by strengthening the nucleophilicity of the oxygen atom in the hydroxyl of a 2-hydroxyethyl ester group compared with that of EG; for example, by the formation of an intramolecular cycle involving a hydrogen bond. Simultaneously, it has been found that in the system simulating PET polycondensation in the presence of dicarboxylic acids the reaction mechanism involves the catalysis by a proton formed during the carboxyl group dissociation and accepted by the 2-hydroxyethyl ester group.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 919-921 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 927-930 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 935-935 
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 943-947 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The heterogeneous polymerization of acrylonitrile photoinitiated by naphthalene is influenced by the polarity of the reaction medium. The rate of initiation increases with the increasing dielectric strength of the reaction medium. A similar trend is observable for Stern-Volmer constants of naphthalene fluorescence quenching by acrylonitrile. The ratio kp/kt1/2 of the rate constant for propagation and termination reactions is not influenced by a change in the polarity of the reaction medium. The effect of viscosity on the value of kp/kt1/2 known for polymerization in a homogeneous medium was not observed in the reaction systems studied.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1267-1277 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
    Notes: The γ-ray-induced addition reaction of carbon tetrachloride onto syndiotactic 1,2-polybutadiene film and liquid 1,2-polybutadiene was carried out at room temperature. In the film gelation was pronounced and the rate of addition increased as the crystallinity of the polymer decreased. In the liquid gelation, which makes the polymer insoluble in carbon tetrachloride, did not take place, although a definite crosslinking reaction was noticed. In this case the appearance of the product changed from a viscous liquid to a white powder as the reaction proceeded. Its structure was compared with that of chlorinated 1,2-polybutadiene. The addition of carbon tetrachloride to the vinyl group in liquid 1,2-polybutadiene caused an anti-Markownikoff-type reaction and was accompanied by an unexpectedly large vinyl depletion in the polymer. The total decrease in the vinyl group was found to be much larger than that brought about by the addition of carbon tetrachloride. This discrepancy was attributed to a cyclization and crosslinking reaction ascribed to the vinyl group bound by the main chain. Cyclization and crosslinking were less noticeable in the chlorination than in the carbon tetrachloride.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1353-1366 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Products from the thermal decomposition of a chlorinated aromatic polyamide fabric are described for conditions of pyrolysis and flaming and nonflaming oxidative degradation. Volatile degradation products were identified by gas chromatography-mass spectrometry (GC-MS) and the condensible fraction, by infrared (IR) spectroscopy, high-pressure liquid chromatography (HPLC), and MS. Nonvolatile char was characterized by IR and elemental analysis. Twenty-one compounds were identified as volatile products from pyrolysis at 550°C; the condensible material contained ammonium chloride and at least 22 organic compounds. From volatile compounds produced in flaming oxidative degradation 21 compounds were identified, of which CO, CO2, and H2O were prominent. Nonflaming oxidative degradation at 400 and 550°C produced 11 and 21 volatile identifiable compounds, respectively, and results from experiments at the higher temperature compared favorably with results from the flaming experiments. By comparison of data from this work with those from unchlorinated analogs (described in an earlier article), it is concluded that the incorporation of chlorine into the polymeric structure lowers the temperature for the onset of thermal degradation and alters the type and concentration of thermolytic products. The major degradation products can be explained by a mechanism similar to that proposed for aromatic polyamides with the exception of the formation of substantial amounts of ammonium chloride. It is proposed that the latter is formed by an initial acid-catalyzed hydrolysis reaction which is followed by deammoniation or by an intermolecular process that involves an isoimide intermediate.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1393-1400 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The redox system of potassium persulfate-thiomalic acid (I1-I2) was used to initiate the polymerization of acrylamide (M) in aqueous medium. For 20-30% conversion the rate equation is \documentclass{article}\pagestyle{empty}\begin{document}$$ R_p = - \frac{{d[{\rm M}]}}{{dt}} = K[{\rm M}][{\rm I}_1]^{1/2} $$\end{document} where Rp is the rate of polymerization. Activation energy is 8.34 kcal deg-1 mole-1 in the investigated range of temperature 25-45°C. Mn is directly proportional to [M] and inversely to [I1]. The range of concentrations for which these observations hold at 35°C and pH 4.2 are [I1] = (1.0-3.0) × 10-3, [I2] = (3.0-7.5) × 10-3, and [M] = 5.0 × 10-2-3.0 × 10-1 mole/liter.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1411-1418 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electroinitiated polymerizations of styrene, 2-vinylnaphthalene, and 9-vinylanthracene were compared in sulfolane and acetone solvents in the presence of ZnCl2. The relative orders of polymerization rates and polymerization efficiencies, in both solvents, were 9-vinylanthracene 〉 2-vinylnaphthalene 〉 styrene, with faster rates and higher efficiencies occurring in sulfolane. Data obtained from viscosity and gel permeation chromatography (GPC) studies indicate that the molecular weights of the polymers produced in these systems are extremely low, 〈5000. Chemical composition and infrared (IR) spectral data suggest that abnormal transfer reactions (possibly from solvent) may be occurring in the electroinitiated 9-vinylanthracene polymerizations. The polymerization mechanism appears to be cationic in these monomer-solvent systems with ZnCl2.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1431-1440 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Butene(2B) copolymerizes with 3-heptene(3H) and 4-methyl-2-pentene(4M2P) by a monomer-isomerization copolymerization mechanism in the presence of TiCl3-(C2H5)3Al catalyst at 80°C to yield the copolymers of 1-olefin units. By comparison, the copolymerization of 1-butene(1B) with 4-methyl-1-pentene(4M1P) was also carried out under similar conditions. The composition of the copolymers obtained from these copolymerizations was determined from the ratios of optical densities D723/D1380 and D1170/D1380 in their infrared (IR) spectra. The apparent monomer reactivity ratios for the monomer-isomerization copolymerization of 2B with 3H and 4M2P, in which the concentration of olefin monomer in the feed was used as 2-olefin, were determined as follows: cis-2B(M1)/3H(M2); r1 = 4.00, r2 = 0.20: trans-2B(M1)/3H; r1 = 3.50, r2 = 0.20; 4M2P(M1)-trans-2B(M2): r1 = 0.05, r2 = 9.0. These results indicate that the isomerization of 2-olefins to 1-olefins was important to monomer-isomerization copolymerization.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1453-1461 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
    Notes: The copolymerization of 3-methyl-1-butene (3M1B), 2-methyl-2-butene (2M2B), or 2-methyl-1-butene (2M1B) with trans-2-butene (2B) was attempted in the presence of a Ziegler-Natta catalyst. It was found the 3M1B underwent monomer-isomerization copolymerization with 2B to give a copolymer consisting of both 3M1B and 1-butene (1B) units, with an infrared (IR) spectrum in good agreement with that obtained from the copolymerization of 3M1B with 1B under similar conditions. When the apparent copolymerization parameters obtained by a TiCl3-(C2H5)3Al catalyst were compared, the apparent reactivity of 3M1B observed in the 3M1B-2B system was much higher than that in the 3M1B-1B system. However, 2M2B and 2M1B did not undergo monomer-isomerization copolymerization with 2B, and only the homopolymer of 1B was obtained under similar conditions.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1573-1581 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
    Notes: Macrocyclic polyether or crown ether ester derivatives of acrylic and methacrylic acid were synthesized and polymerized. The cation binding properties of the polymers determined by extraction of picrate salts were similar to those obtained for poly(crown ether)s derived from styrene. In the presence of a crown-complexable cation both polymers form insoluble polysalt complexes with sodium carboxymethylcellulose, potassium poly(styrene sulfonate), and potassium polyacrylate. The extent of precipitation depends on the type and concentration of cation as well as on the ratio polyanion to poly(crown ether). The precipitate appears to have an equal number of positive and negative charges. An insoluble hydrogen-bonded complex is formed in the absence of salt when poly(vinylbenzo-18-crown-6) and poly(acrylic acid) are mixed in 0.01M HCl. Organic solutes bound to the poly(crown ether)s, which occur in an aqueous mixture of poly(vinylbenzo-18-crown-6) and picrate anions, are precipitated with the poly(crown ether) when the polysalt complex is formed.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1595-1604 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of enantiomerically enriched t-butyl thiirane was studied. The stereoelectivity and the kinetic behavior are not changed when a monomer of an initial enantiomeric composition lower than a defined limit value is used. When the enantiomeric composition is higher than this value, the stereoelectivity increases. In agreement with kinetic results, a mechanism is proposed involving, in a first step, the complexation of monomer on preexisting sites of the initiator with formation of highly selective chiral active species on which propagation occurs.
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1557-1563 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1565-1568 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
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    Topics: Chemistry and Pharmacology
    Notes: Oxyfluorination and postfluorination behaviors of poly(vinylidene fluoride) films, as well as hydrolysis of the films treated so far, have been studied by infrared (IR) spectrometry. By exposing the polymer film to a mixture of oxygen and fluorine at about 90°C acyl fluoride groups attendant on the scission of the polymer chains were formed. The oxyfluorinated molecules could be further perfluorinated with fluorine alone at about 90°C, leaving many of the acyl fluoride groups. When the properly oxyfluorinated and postfluorinated film was further treated with a hot 6M sodium hydroxide solution the opaque layer of perfluoroalkyl sodium carboxylate of high molecular weight was formed on the surface of the film, to about 3 μm in thickness, which behaved as a cation exchanger. This new type of cation exchanger of perfluoroalkyl carboxylic acid was significantly more acidic than the usual methacrylic acid exchanger. It was able to adsorb the sodium ions from a neutral sodium chloride solution up to about 70% of the exchange capacity and to keep the ions stable while washing them with water, though it could be regenerated to the hydrogen form with a dilute acetic acid solution. The nature of the new ion exchanger has been examined in some detail by IR spectrometry with Li+, Na+, and Cs+ ions.
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  • 82
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1583-1593 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereoelective polymerization of racemic t-butyl thiirane was performed with chiral zinc glycolate. Monomers and polymers of high optical purities were isolated. A new kinetic scheme in which the ratio of the rates of consumption of both enantiomers obeys a second-order relationship is proposed. This behavior is different from that observed for other three-membered ring monomers.
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  • 83
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1739-1758 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Graft copolymers of nucleic acid bases and L-α-amino acids on polyethyleneimine were synthesized, and carboxyl derivatives of adenine and thymine were grafted by the p-nitrophenyl ester method onto linear and branched polyethyleneimine. The carboxyl derivatives of nucleic acid bases were also grafted onto the monomeric graft copolymers of L-α-amino acids on polyethyleneimine; the carboxyl derivatives were obtained by the condensation of polyethyleneimine with L-α-amino acids with a coupling agent.
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  • 84
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1727-1737 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The growth center in the anionic polymerization of methacrylic esters is stabilized with alkaline alkoxides, sodium tert-butoxide in particular. The lifetime of the growth center was investigated in the polymerization of methyl methacrylate by evaluating yield and molecular weight distribution of the polymer formed when the monomer was added in two doses. The average lifetime of the original growth center stabilized by sodium tert-butoxide at 20°C under the given conditions was longer than several minutes. The stabilization of the growth center was also used in the stepwise copolymerization of n-butyl methacrylate and methyl methacrylate. The copolymer thus obtained in high yield was characterized as a block copolymer on the basis of its solubility, nuclear magnetic resonance (NMR) spectra, and measurements of the complex shear modulus.
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  • 85
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1779-1788 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The homogeneous catalyst Re(CO)5X (X = Cl, Br) was found to promote the homopolymerization of terminal alkynes at elevated temperatures. Detection and structure characterization of low-molecular-weight products provided evidence of the formation of a metal-acetylide species as the initiator of polymerization, and propagation occurs by a series of insertion reactions of coordinated alkynes into metal-carbon bonds of the growing chain. Evidence of the active forms of the catalyst comes from studies on gas evolution, catalyst derivatization, and copolymerization reactions. The final polymers have a linear, polyconjugated macrostructure, and the formation of aromatic species was not detected in these reactions.
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  • 86
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1771-1777 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It was found that N,N,N′,N′-tetramethylethylene diamine and hexamethyl phosphorus triamide minimize chain transfer reactions in the polymerization of 1,3-butadiene in hydrocarbon solvent with alkylsodium or alkylpotassium initiators. The polymers obtained with alkylsodium initiators had a high molecular weight and high vinyl content at 90-95% conversion. The molecular weight of the polybutadiene made by alkylsodium and alkylpotassium initiators was dependent on the polymerization temperatures and modifier ratios, but the vinyl contents were independent of the modifier ratios. Vinyl contents of alkylpotassium-initiated polymers showed a slight dependency on polymerization temperature; the vinyl contents of alkylsodium-initiated polymers were independent of temperature. Addition of lithium tert-butoxide and potassium tert-amylate to these initiators in the presence of the modifiers affected the molecular weight but not the microstructure.
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  • 87
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1795-1800 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Copolymerization of methyl trifluoroacrylate (MTFA) with propylene in bulk was induced by γ irradiation. A wide range of the initial monomer composition gives an equimolar alternating co-polymer. The reactivity ratios of r1 (MTFA) and r2 (propylene) were determined to be 0.01 and 0.005, respectively. The polymerization rate at an equimolar monomer composition is proportional to the 1.0 power of the dose rate. The dose rate dependency of higher than 0.5 may be ascribed to unimolecular termination due to a degradative chain transfer of propagating radicals to propylene. The G values of the initiating radical formation and the polymerization reaction were calculated to be 1.78 and 1336, respectively. The dependence of the copolymerization rate on the temperature was small, and the activation energy of copolymerization was 1.1 kcal/mole from -6 to 50°C.
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  • 88
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1887-1888 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 89
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1911-1921 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: α-Isobutyl-L-aspartate oligomers, Z-(α-i-Bu-Asp)2n-OEt (n = 1-5), where Z = benzyloxycarbonyl and OEt = ethyl ester, were prepared stepwise, and their conformation in solution was investigated by optical rotation, circular dichroism (CD), and NMR spectroscopy. The oligomers up to hexamer existed only in a disordered form. An ordered structure began to appear at octamer and decamer in chloroform and 2,2,2-trifluoroethanol. The ordered structure was more favorable for N-unprotected oligomers, H-(α-i-Bu-Asp)2n-OEt, in comparison with the corresponding Z-(α-i-Bu-Asp)2n-OEt. The effects of oligomer concentration and temperature on the structure were slightly observed. The most likely ordered structure was a β form caused by intramolecular association.
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  • 90
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1963-1976 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thiophene was polymerized in high yield on exposure to aluminum chloride in solvent under mild conditions. Experimental evidence [IR, NMR, UV, and mass spectra, elemental analyses, reductive desulfurization, and comparison with the literature trimer of thiophene (prepared with phosphoric acid)] suggests the following structure: From gel permeation chromatography an average weight of 1290 was obtained, which corresponded to the presence of 15 rings; the highest-molecular-weight chains contained about 192 rings. Mechanistically, participation of cationic intermediates is proposed. Apparently chain extension can occur by various routes, including participation of neutral oligomer molecules.
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  • 91
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1953-1961 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermodynamic parameters for the interaction of the hydrophobic fluorescent probe, 2-p-toluidinylnaphthalene-6-sulfonate (TNS), and polycations that contain a piperidinium cation and various nonpolar pendant groups were calculated. Binding is exothermic and involves a positive entropy gain. The contribution of the entropy term to the free energy change tends to increase with increasing hydrophobicity of the polymers. The intensity of the fluorescence of TNS is enhanced when the probe binds to the polycations. The nature and phenomena of hydrophobic fluorescent probe binding with the polymers are discussed.
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  • 92
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1991-2001 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyrolysis/mass spectrometric studies have been made on polystyrene, poly(vinyl chloride), and poly(methyl methacrylate) with electron ionization (EI) and chemical ionization (CI) mass spectrometry and a variable temperature probe for direct insertion into the source of the mass spectrometer. Similar results obtained with EI and CI mass spectrometry are in agreement with previous experiments. Advantages of the simplification of spectra in the CI made, as well as the advantages of using both techniques for identification of pyrolysis products, are discussed.
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  • 93
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 2003-2011 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbon dioxide was copolymerized with 2-methylaziridine and 1-phenethylaziridine in the presence of organozinc coordination catalysts. Fully alternating copolymers-polyurethanes were obtained. Relations between reaction conditions and polymer yield are given. On the basis of these results a probable scheme of the copolymerization reaction is proposed.
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  • 94
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 193-202 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Potentiometric titrations in water of high-molecular-weight partly hydrolyzed polyacrylamides were analyzed by the Lifson - Katchalsky rodlike model. A fair concordance was found between theory and experimental curves with pK0 of acid functions of about 4.75 when 0 〈 τ 〈 0.49. Two methods were derived to calculate the parameter n of the extended Henderson-Hasselbach equation by using a series expansion of pKa vs. α, not yet reported in the literature. A new equation for n was established and comparison between two sets of values of n, obtained by using the theoretical ΔpK curves and series expansion is discussed.
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  • 95
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 237-244 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Q-e concept of the Alfrey and Price1 has been applied successfully to the prediction of the pressure effect on the individual reactivity ratios in free-radical copolymerizations. Although the Q value of a given monomer is generally little affected by an increase in pressure, the e value is pressure dependent. The knowledge of the Q and e values at high pressures permits the prediction of variations in reactivity ratios with pressure. Some important consequences have been drawn from this concept.
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  • 96
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 2039-2054 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction between tert-butylchloride (t-BuCl) and dimethylcyclopentadienylaluminum (Me2AlCPD) was studied as a model for initiation by the tert-butyl cation (t-Bu⊕) and termination by cyclopentadienylation by the Me2Al(CPD)Cl⊖ counteranion of isobutylene polymerization. All reaction products formed in this model system have been identified and quantitatively determined. A comprehensive scheme that indicates pathways to these products was developed (scheme III). It is proposed that the predominant product, tert-butylcyclopentadiene (t-BuCPD), arises in the collapse of the t-Bu⊕-Me2Al(CPD)Cl⊖ ion pair, mainly by CPD⊖ transfer to the tert-butyl cation. The minor products are neopentane (t-BuMe) and isobutylene (i-C4H8), which are probably formed, respectively, by Me⊖ transfer to and proton loss from the t-butyl cation. Cyclopentadienylation selectivity increases by lowering the temperature and extrapolation of results suggests 100% cyclopentadienylation at -55°C. The t-BuCl/Me2AlCPD ratio strongly influences the overall reaction pathway. The reaction is first order in t-BuCl with ΔEa of ca. 7 kcal/mole (1,2-dichloroethane or chlorobenzene solvents, +24 to -29°C). Indirect evidence indicates that the kinetic product of cyclopentadienylation is 5-t-BuCPD and that this isomer cannot be tert-butylated; that is, the initiation of 5-t-BuCPD polymerization by t-Bu⊕ is sterically unfavorable. Detailed analysis of the chemistry and kinetics of the t-BuCl/Me2AlCPD model system holds important clues to the controlled polymerization of olefins leading to macromolecules with cyclopentadiene (CPD) termini.
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  • 97
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 2087-2091 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radiation-induced bulk polymerization of vinyl chloride has been carried out under centrifugation at 21°C. The polymerization rate and the molecular weight of the polymer produced were found to remain constant in the low-conversion region and to be equal to the corresponding values that were obtained by extrapolation at zero conversion in normal polymerization. This was at variance with the case of normal polymerization in which both quantities exhibit a continuous increase from the start of the polymerization. Such an increase is to be associated with the presence of large agglomerates, formed through flocculation of initially originated particles, in the liquid monomer phase during the polymerization under quiescent conditions. For the constancy of the kinetic parameters in the polymerization under centrifugation it should be assumed that in the system there remain dispersed only particles not yet flocculated.
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  • 98
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrodialytic behavior of cation exchange membrane having cationic polyelectrolyte layer on its surface (relative transport number between two cations, PM1M2, current efficiency, and electric resistance of the membrane during the electrodialysis) was measured using various cations, and the mechanism of selective permeation of lower-valent cations than the higher and of larger hydrated cations than the smaller was investigated. The following conclusions were obtained: (1) the cationic polyelectrolyte layer narrowed the pathway for ions; (2) when the pathway was made narrower by other methods, the remarkable change of the permselectivity of the membrane did not occur; (3) the effectiveness of the cationic polyelectrolyte layer was depressed by the treatment with anionic polyelectrolytes to neutralize the cationic charge on the membrane surface; and (4) the cation with larger hydrated diameter (potassium ions) more easily permeated through the membrane having the polyelectrolyte layer than that with the smaller hydrated diameter (sodium ions). It is concluded that the change of PM1M2 by the cationic charge layer on the membrane surface is based on the difference in the strength of the electrostatic repulsion between two cations against the cationic charge layer.
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  • 99
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 2093-2101 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the presence of an optical active amyloxyaluminum or menthoxyaluminum chloride the asymmetric-induction alternating copolymerization of benzofuran or 1,3-cyclooctadiene and acrylonitrile or methacrylonitrile was investigated. The sign of optical rotation of copolymers was positive or negative, depending on the kind of catalyst used. The optical activity of copolymers of benzofuran and acrylonitrile attains a maximum value at an equimolar composition. The highest specific rotation [α]D of copolymers of benzofuran and acrylonitrile prepared in the presence of stoichiometric amount of ( - )-menthoxyaluminum dichloride with respect to acrylonitrile was about -8°. The stereo-structure of acrylonitrile unit may be controlled by the optical active aluminum compound onto which a strong coordination of acrylonitrile may occur.
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  • 100
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 2103-2118 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanism of cyclic oligomer formation has been kinetically studied by determining the rate of the formation of cyclic oligomers during melt of poly(ethylene terephthalate) (PET) at several levels of average molecular weight, which were obtained by fractionation and did not initially contain oligomers. The experimental rate equation of cyclic oligomer formation was introduced and then compared with the rate equation derived theoretically. The close agreement between the two equations suggested that the cyclic oligomer formation takes place according to cyclodepolymerization by the action of hydroxyl end groups in PET. The relation is represented as [C] = m·[OH]0·t1-n, where [C] is the concentration of cyclic oligomers, [OH]0 is the initial concentration of hydroxyl end groups, m and n are constants, and t is melting time. A method has also been developed for separating cyclic oligomers from PET using dimethylformamide (DMF) as a solvent.
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