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  • Articles  (235)
  • Physics  (202)
  • Rats, Inbred Strains  (33)
  • 1985-1989
  • 1980-1984  (235)
  • 1925-1929
  • 1983  (235)
  • Physics  (235)
Collection
  • Articles  (235)
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Publisher
Years
  • 1985-1989
  • 1980-1984  (235)
  • 1925-1929
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Journal
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  • 1
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    Regulation of carcinogen metabolism in the rat ovary by the estrous cycle and gonadotropin (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-03-25
    Description: The activity of 7,12-dimethylbenz[a]anthracene hydroxylase in the rat ovary is several times higher in the proestrous phase of the estrous cycle than in the estrous and metestrous plus diestrous phases. Administration of gonadotropin leads to a similar increase in the capacity of the ovary to metabolize xenobiotics. This variation in the activity of 7,12-dimethylbenz[a]anthracene hydroxylase during the estrous cycle may be related to the marked changes in the incidence of ovarian cancer during menopause and in women taking contraceptive pills.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bengtsson, M -- Rydstrom, J -- New York, N.Y. -- Science. 1983 Mar 25;219(4591):1437-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6681915" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Aryl Hydrocarbon Hydroxylases/*metabolism ; Cytochrome P-450 Enzyme System/metabolism ; Epoxide Hydrolases/metabolism ; *Estrus ; Female ; Glutathione Transferase/metabolism ; Gonadotropins, Equine/*pharmacology ; Metestrus ; Ovary/*physiology ; Pregnancy ; Proestrus ; Quinone Reductases/metabolism ; Rats ; Rats, Inbred Strains
    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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    Pimozide blocks establishment but not expression of amphetamine-produced environment-specific conditioning (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-06-17
    Description: Animals with a history of receiving daily injections of +-amphetamine in a specific environment showed a placebo effect (enhanced activity) when injected with saline and placed there; control animals with similar but dissociated drug histories and experience with the test chamber failed to show the effect. The dopamine receptor blocker pimozide antagonized the establishment of conditioning. However, the same dose of pimozide, when given to previously conditioned animals on the placebo test day, failed to antagonize the expression of conditioned activity. Thus, during conditioning dopaminergic neurons mediated a change that subsequently influenced behavior even when dopaminergic systems were blocked. Although schizophrenia may be related to hyperfunctioning of dopamine, neuroleptic drugs, which block dopamine receptors on their first administration, do not have therapeutic effects for a number of days. The results of the pimozide experiments may resolve this paradox.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Beninger, R J -- Hahn, B L -- New York, N.Y. -- Science. 1983 Jun 17;220(4603):1304-6.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6857251" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Conditioning (Psychology)/*drug effects/physiology ; Dextroamphetamine/antagonists & inhibitors/*pharmacology ; Humans ; Male ; Pimozide/*pharmacology ; Rats ; Rats, Inbred Strains ; Receptors, Dopamine/physiology ; Reinforcement (Psychology) ; Schizophrenia/physiopathology
    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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    Direct in vivo monitoring of dopamine released from two striatal compartments in the rat (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-07-08
    Description: Microvoltammetric electrodes were used to monitor dopamine released in the caudate nucleus of the rat after electrical stimulation of the medial forebrain bundle. The time resolution of the technique is sufficient to determine in vivo concentration changes on a time scale of seconds. Direct evidence identifying the substance released as dopamine was obtained both voltammetrically and pharmacologically. Administration of alpha-methyl-p-tyrosine terminates the release of dopamine, although tissue stores of dopamine are still present. Thus there appears to be a compartment for dopamine storage that is not available for immediate release. This compartment appears to be mobilized by amfonelic acid, since administration of this agent after alpha-methyl-p-tyrosine returns the concentration of dopamine released by electrical stimulation to 75 percent of the original amount.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ewing, A G -- Bigelow, J C -- Wightman, R M -- KO 4 NS000356/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1983 Jul 8;221(4606):169-71.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6857277" target="_blank"〉PubMed〈/a〉
    Keywords: Amphetamine/pharmacology ; Animals ; Caudate Nucleus/drug effects/*metabolism ; Dopamine/*metabolism ; Male ; Methyltyrosines/pharmacology ; Microelectrodes ; Naphthyridines/pharmacology ; Rats ; Rats, Inbred Strains ; alpha-Methyltyrosine
    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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  • 4
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    Scientist sues over genetically impure mice (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-08-12
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fox, J L -- New York, N.Y. -- Science. 1983 Aug 12;221(4611):625-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6603019" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Animals, Laboratory ; Jurisprudence ; Mice ; *Mice, Inbred BALB C ; Rats ; Rats, Inbred Lew ; Rats, Inbred Strains ; Research ; United States ; Wisconsin
    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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    Adenosine receptors: autoradiographic evidence for their location on axon terminals of excitatory neurons (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-05-27
    Description: Adenosine receptors were made visible on light microscopy by autoradiography with tritiated cyclohexyladenosine. In the cerebellum, adenosine receptors were absent in Weaver mice, which lack granule cells, and were displaced in Reeler mice, which have displacements of granule cells. Thus, adenosine receptors appear to be located on the axon terminals of excitatory granule cells in the cerebellum. Removal of one eye of a rat depleted adenosine receptors in the contralateral superior colliculus, suggesting that the receptors occur on axon terminals of excitatory projections from retinal ganglion cells. The presence of adenosine receptors on excitatory axon terminals may explain synaptic inhibition by adenosine and the behavioral effects of xanthines.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Goodman, R R -- Kuhar, M J -- Hester, L -- Snyder, S H -- DA-00266/DA/NIDA NIH HHS/ -- MH-18501/MH/NIMH NIH HHS/ -- NS-16375/NS/NINDS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1983 May 27;220(4600):967-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6302841" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine/*physiology ; Animals ; Autoradiography ; Axons/*physiology ; Cerebellum/physiology ; Corpus Striatum/physiology ; Hippocampus/physiology ; Mice ; Mice, Neurologic Mutants ; Rats ; Rats, Inbred Strains ; Receptors, Cell Surface/*physiology ; Receptors, Purinergic ; Retinal Ganglion Cells/physiology ; Synaptic Membranes/physiology ; Thalamus/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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  • 6
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    Vasoactive intestinal polypeptide and muscarinic receptors: supersensitivity induced by long-term atropine treatment (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-04-29
    Description: Long-term treatment of rats with atropine induced large increases in the numbers of muscarinic receptors and receptors for vasoactive intestinal polypeptide in the salivary glands. Since receptors for vasoactive intestinal polypeptide coexist with muscarinic receptors on the same neurons in this preparation, the results suggest that a drug that alters the sensitivity of one receptor may also affect the sensitivity of the receptor for a costored transmitter and in this way contribute to the therapeutic or side effects of the drugs.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hedlund, B -- Abens, J -- Bartfai, T -- New York, N.Y. -- Science. 1983 Apr 29;220(4596):519-21.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6132446" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atropine/*pharmacology ; Gastrointestinal Hormones/*metabolism ; Male ; Neurotransmitter Agents/metabolism ; Rats ; Rats, Inbred Strains ; Receptors, Cholinergic/*drug effects ; Receptors, Muscarinic/analysis/*drug effects ; Salivary Glands/analysis/innervation ; Vasoactive Intestinal Peptide/analysis/*metabolism
    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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    Systemic cholinergic agents induce seizures and brain damage in lithium-treated rats (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-04-15
    Description: Administration of pilocarpine or physostigmine to rats treated with lithium chloride produced sustained limbic seizures, widespread brain damage, and increased concentrations of D-myo-inositol-1-phosphate (a metabolite of the phosphoinositides, lipids involved in membrane receptor function) in the brain. The syndrome was preventable with atropine. The physostigmine doses and concentrations of blood lithium that caused the syndrome are similar to those considered appropriate for psychiatric chemotherapy.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Honchar, M P -- Olney, J W -- Sherman, W R -- MH-14677/MH/NIMH NIH HHS/ -- MH-38894/MH/NIMH NIH HHS/ -- NS-05159/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1983 Apr 15;220(4594):323-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6301005" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atropine/pharmacology ; Brain Chemistry/drug effects ; Chlorides/adverse effects ; Drug Interactions ; Humans ; Inositol/analogs & derivatives/analysis ; *Inositol Phosphates ; Lithium/*adverse effects ; Lithium Chloride ; Male ; Parasympathomimetics/*adverse effects ; Physostigmine/adverse effects ; Pilocarpine/adverse effects ; Rats ; Rats, Inbred Strains ; Seizures/*chemically induced ; Substance-Related Disorders/*etiology
    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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  • 8
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    Inhibition of gastric acid secretion in rats by intracerebral injection of corticotropin-releasing factor (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-11-25
    Description: Intracisternal injection of ovine corticotropin-releasing factor (CRF) into the pylorus-ligated rat or the rat with gastric fistula resulted in a dose-dependent inhibition of gastric secretion stimulated with pentagastrin or thyrotropin-releasing hormone. When injected into the lateral hypothalamus--but not when injected into the cerebral cortex--CRF suppressed pentagastrin-stimulated acid secretion. The inhibitory effect of CRF was blocked by vagotomy and adrenalectomy but not by hypophysectomy or naloxone treatment. These results indicate that CRF acts within the brain to inhibit gastric acid secretion through vagal and adrenal mechanisms and not through hypophysiotropic effects.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tache, Y -- Goto, Y -- Gunion, M W -- Vale, W -- River, J -- Brown, M -- AM30110/AM/NIADDK NIH HHS/ -- New York, N.Y. -- Science. 1983 Nov 25;222(4626):935-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6415815" target="_blank"〉PubMed〈/a〉
    Keywords: Adrenalectomy ; Animals ; Brain/*drug effects ; Cerebral Cortex/drug effects ; Corticotropin-Releasing Hormone/administration & dosage/*pharmacology ; Dose-Response Relationship, Drug ; Gastric Acid/*secretion ; Hypophysectomy ; Hypothalamus/drug effects ; Male ; Pentagastrin/antagonists & inhibitors ; Rats ; Rats, Inbred Strains ; Thyrotropin-Releasing Hormone/antagonists & inhibitors ; Vagotomy
    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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  • 9
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    Insulin-like growth factors: a role in growth hormone negative feedback and body weight regulation via brain (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-04-01
    Description: Intracerebroventricular administration of ILA's, a preparation enriched in insulin-like growth factors, caused a marked decrease in growth hormone secretory episodes and in body weight associated with reduced food intake over 24 hours. Central injection of insulin and bovine serum albumin had no such effects. These findings suggest that insulin-like growth factors play a role in growth hormone negative feedback and body weight regulation at the level of the central nervous system.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tannenbaum, G S -- Guyda, H J -- Posner, B I -- New York, N.Y. -- Science. 1983 Apr 1;220(4592):77-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6338593" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Body Weight/*drug effects ; Brain/drug effects/*physiology ; Eating/drug effects ; Growth Hormone/antagonists & inhibitors/blood/*physiology ; Insulin/blood/*pharmacology ; Male ; Peptides/*pharmacology ; Rats ; Rats, Inbred Strains ; Somatomedins/*pharmacology
    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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  • 10
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    Potent interaction between glucocorticoids and growth hormone-releasing factor in vivo (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-08-05
    Description: Administration of dexamethasone significantly enhanced the pituitary growth hormone response to growth hormone-releasing factor in intact as well as adrenalectomized rats. Thus the inhibitory effects of glucocorticosteroids on somatic growth which involve an interaction of these steroids and growth hormone at a peripheral level may also involve a modification of pathways within the central nervous system that regulate normal growth hormone secretion.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wehrenberg, W B -- Baird, A -- Ling, N -- AM-18811/AM/NIADDK NIH HHS/ -- HD 09690/HD/NICHD NIH HHS/ -- New York, N.Y. -- Science. 1983 Aug 5;221(4610):556-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6408735" target="_blank"〉PubMed〈/a〉
    Keywords: Adrenalectomy ; Animals ; Dexamethasone/pharmacology ; Drug Interactions ; Glucocorticoids/*pharmacology ; Growth Hormone/blood/secretion ; Growth Hormone-Releasing Hormone/*pharmacology ; Male ; Rats ; Rats, Inbred Strains
    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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  • 11
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    Increased brain size and cellular content in infant rats treated with an opiate antagonist (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-09-16
    Description: From birth to day 21, rat offspring received daily injections of naltrexone at a dosage that blocked morphine-induced analgesia 24 hours a day. At 21 days, body, brain, and cerebellar weights of naltrexone-injected animals were 18, 11, and 5 percent greater than corresponding control weights. In addition, morphometric analysis of the cerebrum revealed a somatosensory cortex that was 18 percent thicker than that of the controls. The cerebellum of naltrexone-treated rats was 41 percent larger in total area and contained at least 70 percent more glial cells and 30 percent more granule neurons. Neurons derived prenatally were unaffected by drug treatment. These results show that naltrexone can stimulate body and brain growth in rats and suggest a role for the endorphin and opiate receptor system in development.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zagon, I S -- McLaughlin, P J -- New York, N.Y. -- Science. 1983 Sep 16;221(4616):1179-80.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6612331" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Animals, Newborn ; Body Weight/drug effects ; Brain/*drug effects/growth & development/ultrastructure ; Cerebellum/drug effects ; Morphine/*antagonists & inhibitors ; Naloxone/*analogs & derivatives ; Naltrexone/*pharmacology ; Neuroglia/drug effects ; Organ Size/drug effects ; Rats ; Rats, Inbred Strains ; Somatosensory Cortex/drug effects
    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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  • 12
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    Interrelated striated elements in vestibular hair cells of the rat (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-05-06
    Description: Unusual fixation procedures revealed a series of interrelated striated organelles in type I and type II vestibular hair cells of the rat; these organelles seemed to be less well developed in cochlear hair cells. The findings suggest that contractile elements may play a role in sensory transduction in the inner ear, particularly in the vestibular system.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ross, M D -- Bourne, C -- New York, N.Y. -- Science. 1983 May 6;220(4597):622-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6682246" target="_blank"〉PubMed〈/a〉
    Keywords: Actins/physiology ; Animals ; Cell Membrane/ultrastructure ; Cytoskeleton/ultrastructure ; Hair Cells, Auditory/*ultrastructure ; Microscopy, Electron ; Organoids/ultrastructure ; Rats ; Rats, Inbred Strains
    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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  • 13
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    Nicotinic cholinergic receptor binding sites in the brain: regulation in vivo (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-04-08
    Description: Tritiated acetylcholine was used to measure binding sites with characteristics of nicotinic cholinergic receptors in rat brain. Regulation of the binding sites in vivo was examined by administering two drugs that stimulate nicotinic receptors directly or indirectly. After 10 days of exposure to the cholinesterase inhibitor diisopropyl fluorophosphate, binding of tritiated acetylcholine in the cerebral cortex was decreased. However, after repeated administration of nicotine for 10 days, binding of tritiated acetylcholine in the cortex was increased. Saturation analysis of tritiated acetylcholine binding in the cortices of rats treated with diisopropyl fluorophosphate or nicotine indicated that the number of binding sites decreased and increased, respectively, while the affinity of the sites was unaltered.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schwartz, R D -- Kellar, K J -- 507 RR05360-20/RR/NCRR NIH HHS/ -- GM07443/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1983 Apr 8;220(4593):214-6.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6828889" target="_blank"〉PubMed〈/a〉
    Keywords: Acetylcholine/metabolism ; Animals ; Brain/*physiology ; Brain Chemistry/drug effects ; Cerebral Cortex/analysis/physiology ; Isoflurophate/pharmacology ; Male ; Nicotine/metabolism/pharmacology ; Rats ; Rats, Inbred Strains ; Receptors, Cholinergic/*physiology ; Receptors, Nicotinic/analysis/*physiology
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  • 14
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    Retinal capillaries: basement membrane thickening by galactosemia prevented with aldose reductase inhibitor (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-09-16
    Description: A twofold thickening of capillary basement membranes of rat retinas resulting from dietary galactose was prevented by sorbinil, an inhibitor of aldose reductase. Since the basement membrane thickening was ultrastructurally similar to that typical of diabetic retinopathy, it may indicate changes in vessel permeability and susceptibility to hemorrhage. Galactosemic rats should be useful models for studying basement membrane-related complications of diabetes and for examining the potential biochemical regulation of basement membrane synthesis by aldose reductase inhibitors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Robison, W G Jr -- Kador, P F -- Kinoshita, J H -- New York, N.Y. -- Science. 1983 Sep 16;221(4616):1177-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6612330" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Basement Membrane/*pathology ; Capillaries/pathology ; Diabetic Retinopathy/etiology ; Disease Models, Animal ; Galactosemias/drug therapy/*pathology ; Imidazoles/*therapeutic use ; *Imidazolidines ; Male ; Rats ; Rats, Inbred Strains ; Retinal Vessels/*pathology
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  • 15
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    Single-channel fluctuations in bimolecular lipid membranes induced by rat olfactory epithelial homogenates (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-05-13
    Description: Chemosensitive single-channel fluctuations were observed to be induced in essentially solvent-free lipid bimolecular membranes by the addition of sonicated homogenates of rat olfactory epithelium. The chemosensitive channels were not observed when respiratory epithelium homogenates were used instead. Ionic selectivity is consistent with potassium ions as the charge carrier. These channels may be associated with the initial events of chemoreception in the rat olfactory epithelium.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vodyanoy, V -- Murphy, R B -- New York, N.Y. -- Science. 1983 May 13;220(4598):717-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6301014" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Anura ; Chemoreceptor Cells/physiology ; Epithelium/physiology ; Ion Channels/*drug effects ; Male ; Membranes/drug effects ; Olfactory Mucosa/*physiology ; Rats ; Rats, Inbred Strains ; Smell/physiology
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  • 16
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    Dopamine modulation of the effects of gamma-aminobutyric acid on substantia nigra pars reticulata neurons (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-04-08
    Description: Studies were conducted to assess whether basal ganglia output neurons originating in the substantia nigra pars reticulata might be affected by dopamine released from dendrites of neighboring substantia nigra pars compacta neurons. Dopamine applied by iontophoresis increased the baseline firing rates of approximately half of the substantia nigra pars reticulata cells tested. The more significant finding, unrelated to the increase in firing, was the ability of dopamine to attenuate the inhibitory responses of these cells to iontophoretically applied gamma-aminobutyric acid. These findings suggest a role for dopamine as a neuromodulator and further suggest that it can act at sites beyond the striatum to modify transmission from the basal ganglia to motor nuclei.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Waszcak, B L -- Walters, J R -- New York, N.Y. -- Science. 1983 Apr 8;220(4593):218-21.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6828891" target="_blank"〉PubMed〈/a〉
    Keywords: Action Potentials/drug effects ; Animals ; Dopamine/*pharmacology ; Iontophoresis ; Male ; Neurons/*drug effects ; Norepinephrine/pharmacology ; Rats ; Rats, Inbred Strains ; Substantia Nigra/*drug effects ; gamma-Aminobutyric Acid/*pharmacology
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  • 17
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    Effects of tyrosine administration on serum biopterin in normal controls and patients with Parkinson's disease (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-01-07
    Description: After administration of tyrosine, total concentration of biopterin, the cofactor for tyrosine hydroxylase, was increased in the striatum, adrenal glands, and serum of rats, and in the serum of humans. Serum biopterin is lower in patients with Parkinson's disease than in normal controls. After oral administration of tyrosine, the increase in serum biopterin concentration was smaller in patients with Parkinson's disease (less than twofold) than in healthy controls (three-to sevenfold). These results suggest that tyrosine may have a regulatory role in biopterin biosynthesis and that patients with Parkinson's disease may have some abnormality in the regulation of biopterin biosynthesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yamaguchi, T -- Nagatsu, T -- Sugimoto, T -- Matsuura, S -- Kondo, T -- Iizuka, R -- Narabayashi, H -- New York, N.Y. -- Science. 1983 Jan 7;219(4580):75-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6849120" target="_blank"〉PubMed〈/a〉
    Keywords: Administration, Oral ; Adrenal Glands/metabolism ; Alanine/pharmacology ; Animals ; Biopterin/*blood ; Corpus Striatum/metabolism ; Humans ; Injections, Intraperitoneal ; Liver/metabolism ; Male ; Parkinson Disease/*blood ; Pteridines/*blood ; Rats ; Rats, Inbred Strains ; Time Factors ; Tyrosine/administration & dosage/*pharmacology
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  • 18
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    Normalization of spiroperidol binding in the denervated rat striatum by homologous grafts of substantia nigra (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-11-25
    Description: Transplantation of embryonic substantia nigra into the adult rat brain decreases the motor asymmetry that is produced by dopamine receptor supersensitivity after a unilateral lesion of the substantia nigra. The authors report that this effect of transplantation is specific to grafts of substantia nigra. They also report that, in conjunction with the decrease in motor asymmetry, these grafts cause postsynaptic dopaminergic binding sites to return to normal density as measured by tritiated spiroperidol autoradiography. Thus, in animals with brain lesions, grafts of substantia nigra produce a long-term alteration in the functional status of host brain cell receptors that is associated with a reduction in the behavioral deficit.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Freed, W J -- Ko, G N -- Niehoff, D L -- Kuhar, M J -- Hoffer, B J -- Olson, L -- Cannon-Spoor, H E -- Morihisa, J M -- Wyatt, R J -- MH-00289/MH/NIMH NIH HHS/ -- MH-25951/MH/NIMH NIH HHS/ -- NS-09199/NS/NINDS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1983 Nov 25;222(4626):937-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6635666" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Apomorphine/pharmacology ; Autoradiography ; Denervation ; Dextroamphetamine/pharmacology ; Motor Activity/drug effects ; Rats ; Rats, Inbred Strains ; Receptors, Dopamine/*metabolism ; Spiperone/metabolism ; Substantia Nigra/*transplantation
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  • 19
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    Phorbol ester receptors: autoradiographic identification in the developing rat (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-12-02
    Description: Autoradiography with 3H-labeled phorbol dibutyrate was used for the light microscopic detection of phorbol ester receptors in rat fetuses. In 15- and 18-day fetuses, as well as in adult rats, receptors were found to be concentrated in the central nervous system. The localization of receptors in the ventral marginal zone of the fetal neural tube, the lens of the eye, and other sites suggests a role for phorbol ester receptors in cellular process extension and cell-cell interaction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Murphy, K M -- Gould, R J -- Oster-Granite, M L -- Gearhart, J D -- Snyder, S H -- New York, N.Y. -- Science. 1983 Dec 2;222(4627):1036-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6316499" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Autoradiography ; Brain/embryology ; Brain Chemistry ; *Caenorhabditis elegans Proteins ; Carrier Proteins ; Cell Communication ; Cell Division ; Central Nervous System/analysis/*embryology ; Eye/embryology ; Fetus/*analysis ; Intestines/embryology ; Lens, Crystalline/embryology ; Phorbol 12,13-Dibutyrate ; Phorbol Esters/*metabolism ; Phorbols/*metabolism ; *Protein Kinase C ; Rats ; Rats, Inbred Strains ; Receptors, Cell Surface/*analysis ; *Receptors, Drug
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  • 20
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    Alcohol-induced spasms of cerebral blood vessels: relation to cerebrovascular accidents and sudden death (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-04-15
    Description: Ethyl alcohol produced graded contractile responses in rat cerebral arterioles and venules in vivo and in isolated canine basilar and middle cerebral arteries at a concentration range (10 to 500 milligrams per deciliter) which parallels that needed for its graded effects of euphoria, mental haziness, muscular incoordination, stupor, and coma in humans. Two specific calcium antagonists, nimodipine and verapamil, prevented or reversed the alcohol-induced cerebrovasospasm and thus may prove valuable in treating the hypertension and stroke observed in heavy users of alcohol.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Altura, B M -- Altura, B T -- Gebrewold, A -- DA02339/DA/NIDA NIH HHS/ -- HL29600/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1983 Apr 15;220(4594):331-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6836278" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cerebral Arteries/drug effects ; Cerebrovascular Circulation/drug effects ; Cerebrovascular Disorders/*chemically induced ; Death, Sudden/*etiology ; Dogs ; Ethanol/*adverse effects ; Humans ; Ischemic Attack, Transient/*chemically induced ; Male ; Rats ; Rats, Inbred Strains ; Vasoconstriction/drug effects
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  • 21
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    Endogenous pyrogen activity in human plasma after exercise (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-05-06
    Description: Plasma obtained from human subjects after exercise and injected intraperitoneally into rats elevated rat rectal temperature and depressed plasma iron and zinc concentrations. The pyrogenic component was heat-denaturable and had an apparent molecular weight of 14,000 daltons. Human mononuclear leukocytes obtained after exercise and incubated in vitro released a factor into the medium that also elevated body temperature in rats and reduced trace metal concentrations. These results suggest that endogenous pyrogen, a protein mediator of fever and trace metal metabolism during infection, is released during exercise.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cannon, J G -- Kluger, M J -- AI 13878/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1983 May 6;220(4597):617-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6836306" target="_blank"〉PubMed〈/a〉
    Keywords: Adult ; Animals ; Body Temperature/drug effects ; Female ; Humans ; *Interleukin-1 ; Iron/blood ; Leukocytes/physiology ; Male ; Molecular Weight ; *Physical Exertion ; Proteins/physiology ; Pyrogens/blood/*metabolism ; Rats ; Rats, Inbred Strains ; Zinc/blood
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  • 22
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    Local cerebral blood flow increases during auditory and emotional processing in the conscious rat (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-08-05
    Description: Local cerebral blood flow was measured in rats by the 14C-labeled iodoantipyrine technique with quantitative autoradiography during the processing of environmental stimuli. Presentation of a tone increased blood flow in the auditory but not the visual pathway. When the animal had previously been conditioned to fear the tone, blood flow additionally increased in the hypothalamus and amygdala. Local cerebral blood flow can thus be used to detect patterns of cerebral excitation associated with transient (30- to 40-second) mental events in experimental animals.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉LeDoux, J E -- Thompson, M E -- Iadecola, C -- Tucker, L W -- Reis, D J -- HL 18974/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1983 Aug 5;221(4610):576-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6867731" target="_blank"〉PubMed〈/a〉
    Keywords: Acoustic Stimulation ; Amygdala/blood supply ; Animals ; Autoradiography ; Brain/*blood supply/physiology ; Consciousness/physiology ; Emotions/*physiology ; Hearing/*physiology ; Hypothalamus/blood supply ; Male ; Rats ; Rats, Inbred Strains
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  • 23
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    L-tryptophan: a common denominator of biochemical and neurological events of acute hepatic porphyria? (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-12-02
    Description: Hepatic porphyrias are disorders of heme synthesis characterized by genetically determined lesions of one of the key enzymes of heme synthesis. In carriers of such lesions, several factors (drugs, environmental chemicals, or diet) precipitate acute and often fatal attacks of neurologic dysfunction, which are promptly relieved by intravenous infusion of heme. However, the mechanism of such heme-induced amelioration remains elusive. To probe this mechanism, the biochemical events triggered by acute hepatic heme deficiency were examined in an animal model of chemically induced porphyria. Acute hepatic heme depletion in porphyric rats was found to impair hepatic tryptophan pyrrolase activity which, in turn, elevated tryptophan and 5-hydroxytryptamine turnover in the brain. These alterations in porphyric rats were dramatically reversed by parenteral heme administration. These findings suggest that increased tryptophan and 5-hydroxytryptamine in the nervous system may be responsible for the neurologic dysfunctions observed in humans with acute attacks of hepatic porphyria.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Litman, D A -- Correia, M A -- AM-26506/AM/NIADDK NIH HHS/ -- AM-26743/AM/NIADDK NIH HHS/ -- New York, N.Y. -- Science. 1983 Dec 2;222(4627):1031-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6648517" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Brain/*metabolism ; Heme/*deficiency/pharmacology ; Liver/enzymology ; Liver Diseases/complications/*metabolism ; Male ; Nervous System Diseases/etiology ; Porphyrias/complications/*metabolism ; Rats ; Rats, Inbred Strains ; Serotonin/metabolism ; Tryptophan/*metabolism ; Tryptophan Oxygenase/metabolism
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  • 24
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    Fetal brain transplant: reduction of cognitive deficits in rats with frontal cortex lesions (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-07-29
    Description: Frontal cortex and cerebellar tissue from fetal rats was implanted into the damaged frontal cortex of adults. Cognitive deficits in spatial alternation learning that follow bilateral destruction of medial frontal cortex were reduced in rats with frontal cortex implants but not in those with implants of cerebellum. Histological evaluation showed that connections were made between the frontal cortex implants and host brain tissue.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Labbe, R -- Firl, A Jr -- Mufson, E J -- Stein, D G -- New York, N.Y. -- Science. 1983 Jul 29;221(4609):470-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6683427" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Behavior, Animal ; Cerebellum/*transplantation ; Cerebral Cortex/injuries/*transplantation ; Cognition Disorders/*physiopathology ; Fetus/*surgery ; Humans ; Male ; Rats ; Rats, Inbred Strains
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  • 25
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    Evidence for olfactory function in utero (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-07-29
    Description: Pregnant rats received 2-[14C]deoxy-D-glucose (2DG) intravenously on the last day of gestation, and their fetuses were delivered 1 hour later by cesarean section. Fetal brains showed high 2DG uptake spread throughout the accessory olfactory bulb and little or no differential uptake in the main olfactory bulb. These findings demonstrate that functional activity occurs in the accessory olfactory bulb in utero and suggest that the accessory olfactory system may be the pathway by which fetal rats detect the odor quality of their intrauterine milieu.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pedersen, P E -- Stewart, W B -- Greer, C A -- Shepherd, G M -- F32-NS06978/NS/NINDS NIH HHS/ -- NS 16993/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1983 Jul 29;221(4609):478-80.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6867725" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Autoradiography ; Brain/radionuclide imaging ; Deoxyglucose/metabolism ; Female ; Fetus/*physiology ; Olfactory Bulb/physiology/radionuclide imaging ; Pregnancy ; Rats ; Rats, Inbred Strains ; Smell/*physiology
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  • 26
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    Insulin receptor antiserum and plant lectins mimic the direct effects of insulin on nuclear envelope phosphorylation (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-07-29
    Description: Insulin directly inhibits protein phosphorylation in isolated rat liver nuclear envelopes. In the present studies, an antiserum to insulin receptor as well as the plant lectins concanavalin A and phytohemagglutinin mimicked insulin action in isolated nuclear envelopes. These studies suggest that insulin and agents that mimic it may directly regulate nuclear functions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Purrello, F -- Burnham, D B -- Goldfine, I D -- AM 06659/AM/NIADDK NIH HHS/ -- AM 26667/AM/NIADDK NIH HHS/ -- New York, N.Y. -- Science. 1983 Jul 29;221(4609):462-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6346487" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Concanavalin A/pharmacology ; Female ; Immune Sera ; Insulin/*pharmacology ; Lectins/*pharmacology ; Nuclear Envelope/*drug effects/metabolism ; Phosphorylation ; Phytohemagglutinins/pharmacology ; Rats ; Rats, Inbred Strains ; Receptor, Insulin/*immunology
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  • 27
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    Physiological correlates of prolonged sleep deprivation in rats (1983)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 1983-07-08
    Description: The issue of whether sleep is physiologically necessary has been unresolved because experiments that reported deleterious effects of sleep deprivation did not control for the stimuli used to prevent sleep. In this experiment, however, experimental and control rats received the same relatively mild physical stimuli, but stimulus presentations were timed to reduce sleep severely in experimental rats but not in controls. Experimental rats suffered severe pathology and death; control rats did not.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rechtschaffen, A -- Gilliland, M A -- Bergmann, B M -- Winter, J B -- MH-18428/MH/NIMH NIH HHS/ -- MH-4151/MH/NIMH NIH HHS/ -- New York, N.Y. -- Science. 1983 Jul 8;221(4606):182-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6857280" target="_blank"〉PubMed〈/a〉
    Keywords: Adrenal Glands/pathology ; Animals ; Body Weight ; Electroencephalography ; Male ; Organ Size ; Rats ; Rats, Inbred Strains ; Sleep Deprivation/*physiology ; Time Factors
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  • 28
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    Insulin elicits ingestion in decerebrate rats (1983)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 1983-07-08
    Description: Insulin administered to rats reliably elicits ingestion of food. To determine whether the neural mechanisms sufficient to control insulin-elicited ingestion are located in or caudal to the forebrain, decerebrate rats were treated with insulin and ingestive responses were measured. Insulin treatment produced hypoglycemia that was comparable, in magnitude and duration, in control and decerebrate rats. Decerebrate and control rats ingested significantly more sucrose solution while hypoglycemic than while normoglycemic. In contrast, insulin did not augment the water consumption of either group. These data indicate that neural systems caudal to the forebrain are sufficient to control ingestive consummatory behavior through the integration of metabolic signals generated by insulin treatment and taste afferent input from the oropharynx.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Flynn, F W -- Grill, H J -- AM 21397/AM/NIADDK NIH HHS/ -- T32-MH15012/MH/NIMH NIH HHS/ -- New York, N.Y. -- Science. 1983 Jul 8;221(4606):188-90.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6344221" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Blood Glucose/analysis ; Brain/*physiology ; Decerebrate State/physiopathology ; Eating/*drug effects ; Energy Metabolism ; Insulin/*pharmacology ; Male ; Rats ; Rats, Inbred Strains ; Taste/physiology
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  • 29
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    Serum factor supporting long-term survival of rat central neurons in culture (1983)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 1983-06-24
    Description: Gel filtration of serum at pH 3.6 yielded a fraction that supported long-term (months) survival of dissociated rat central neurons in monolayer culture more reliably than the traditionally used unfractionated serum. The cultures remained neuron-rich, because this fraction did not support the proliferation of glia and fibroblasts that occurs in whole serum. With an apparent molecular weight of 55,000 and an isoelectric point of 5.6, the active factor (or factors) in this fraction is distinct from any well-defined growth factor.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kaufman, L M -- Barrett, J N -- NS07044/NS/NINDS NIH HHS/ -- NS12207/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1983 Jun 24;220(4604):1394-6.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6857258" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cattle ; *Cell Survival/drug effects ; Cells, Cultured ; Chromatography, Gel ; Horses ; Isoelectric Focusing ; Molecular Weight ; Nerve Growth Factors/isolation & purification/*pharmacology ; Neurons/drug effects/*physiology ; Rats ; Rats, Inbred Strains ; Spinal Cord/cytology
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  • 30
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    Ionizing radiation decreases veratridine-stimulated uptake of sodium in rat brain synaptosomes (1983)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 1983-06-03
    Description: Veratridine-stimulated uptake of sodium-22 in brain synaptosomes was significantly reduced by ionizing radiation over a dose range of 10 to 1000 rads. The response was dose-dependent and involved a decrease in the maximum effect of veratridine on uptake. The central nervous system may be more sensitive to ionizing radiation than generally thought, perhaps through a loss of the ability of the sodium channel to respond properly to stimulation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wixon, H N -- Hunt, W A -- New York, N.Y. -- Science. 1983 Jun 3;220(4601):1073-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6302846" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Brain/drug effects/*radiation effects ; Dose-Response Relationship, Drug ; Dose-Response Relationship, Radiation ; Ion Channels/drug effects/radiation effects ; Male ; Rats ; Rats, Inbred Strains ; Sodium/*metabolism ; Synaptosomes/drug effects/*radiation effects ; Veratridine/*pharmacology ; Veratrine/*analogs & derivatives
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  • 31
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    High fetal estrogen concentrations: correlation with increased adult sexual activity and decreased aggression in male mice (1983)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 1983-06-17
    Description: In the house mouse (Mus musculus), fetuses may develop in utero next to siblings of the same or opposite sex. The amniotic fluid of the female fetuses contains higher concentrations of estradiol than that of male fetuses. Male fetuses that developed in utero between female fetuses had higher concentrations of estradiol in their amniotic fluid than males that were located between other male fetuses during intrauterine development. They were also more sexually active as adults, less aggressive, and had smaller seminal vesicles than males that had developed between other male fetuses in utero. These findings raise the possibility that during fetal life circulating estrogens may interact with circulating androgens both in regulating the development of sex differences between males and females and in producing variation in phenotype among males and among females.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉vom Saal, F S -- Grant, W M -- McMullen, C W -- Laves, K S -- MH35079/MH/NIMH NIH HHS/ -- RR07053/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1983 Jun 17;220(4603):1306-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6857252" target="_blank"〉PubMed〈/a〉
    Keywords: Aggression/*drug effects ; Amniotic Fluid/analysis ; Animals ; Estradiol/analysis/*pharmacology/physiology ; Female ; Fetus/*drug effects/physiology ; Humans ; Male ; Mice ; Progesterone/pharmacology ; Rats ; Rats, Inbred Strains ; Sex Differentiation/drug effects ; Sexual Behavior, Animal/*drug effects/physiology ; Testosterone/analysis/pharmacology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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    Spontaneous orofacial dyskinesia and dopaminergic function in rats after 6 months of neuroleptic treatment (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-04-29
    Description: A syndrome of spontaneous orofacial dyskinesia was identified in groups of rats treated for 6 months with a wide range of neuroleptic drugs. Phenothiazines, thioxanthenes, and substituted benzamides were particularly likely to induce the syndrome. It was observed in the presence of a functional blockade of dopamine receptors and endured for at least 2.5 months after drug withdrawal. There was no relation between the syndrome and changes in striatal dopamine receptors, as indexed by the binding of tritiated spiperone and tritiated cis(Z)-flupenthixol. The syndrome parallels several of the features of clinical tardive dyskinesia, whose pathophysiology thus may not involve changes in the characteristics of striatal dopamine receptors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Waddington, J L -- Cross, A J -- Gamble, S J -- Bourne, R C -- New York, N.Y. -- Science. 1983 Apr 29;220(4596):530-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6132447" target="_blank"〉PubMed〈/a〉
    Keywords: Administration, Oral ; Animals ; Antipsychotic Agents/*adverse effects ; Dyskinesia, Drug-Induced/*etiology ; Fluphenazine/administration & dosage/adverse effects/analogs & derivatives ; Haloperidol/adverse effects/pharmacology ; Humans ; Injections, Intramuscular ; Male ; Rats ; Rats, Inbred Strains ; Receptors, Dopamine/*drug effects/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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    Differential effects of classical and atypical antipsychotic drugs on A9 and A10 dopamine neurons (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-09-09
    Description: Prolonged treatment with classical antipsychotic drugs decreased the number of spontaneously active dopamine neurons in both the substantia nigra (A9) and the ventral tegmental area (A10) of the rat brain. In contrast, treatment with atypical antipsychotic drugs selectively decreased the number of A10 dopamine neurons. Related drugs lacking antipsychotic efficacy failed to decrease dopamine activity. These findings suggest that the inability of atypical antipsychotic drugs to decrease A9 dopamine neuronal activity may be related to their lower potential for causing tardive dyskinesia and that the inactivation of A10 neurons may be involved in the delayed onset of therapeutic effects during treatment.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉White, F J -- Wang, R Y -- MH 00378/MH/NIMH NIH HHS/ -- MH-34424/MH/NIMH NIH HHS/ -- New York, N.Y. -- Science. 1983 Sep 9;221(4615):1054-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6136093" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antipsychotic Agents/*pharmacology ; Dopamine/*metabolism ; Male ; Metoclopramide/pharmacology ; Mice ; Neurons/metabolism ; Pons/*metabolism ; Rats ; Rats, Inbred Strains ; Substantia Nigra/*metabolism ; Time Factors
    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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    Microstructure and unit-cell orientation in α-polypropylene (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 97-110 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The microstructure of melt-grown dendritic aggregates of the monoclinic α phase of isotactic polypropylene has been examined by optical microscopy, electron microscopy, and electron diffraction. Whereas the tightly crosshatched structure of such dendrites grown in the usual manner from the melt had not heretofore permitted unequivocal determination of unit-cell orientation, crystallization on mica at high temperatures eliminates this problem by suppressing branching and allowing lamellae to grow uninterruptedly to many micrometers in length. In this manner, it is shown that the preferred growth direction in single crystals of α-polypropylene is a*. X-ray diffraction analysis of unidirectionally crystallized specimens shows that the a* axis becomes radial in spherulites of this polymorph. Implications of this growth axis in terms of the branching model and of the crystallographic identification of the amorphous surfaces are discussed. Addition of large amounts of melt diluents is found to impart a distinct curvature to the dendritic crystals, causing their concave sides to face preferentially toward the centers of the resulting spherulitic aggregates.
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    URL: http://dx.doi.org/10.1002/pol.1983.180210107
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    Dynamics of adsorbed polymer chains subjected to flow: The dumbbell model (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 151-157 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dumbbell model of an adsorbed polymer segment is analyzed in order to investigate the response of such segments to a velocity gradient imposed at the solid/liquid interface. It is demonstrated that exact expressions for the time-dependent moments of the distribution function describing the conformation can be obtained. Both a dangling end and an attached loop can be represented and several bulk properties of a polymer film subjected to flow are evaluated.
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    The numerical solution of fujita's integral equation to provide estimates of molecular weight distributions (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 123-139 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A standard model of the behavior of polymers under ultracentrifugation results in Fujita's equation for their molecular weight distribution. Fujita's and related equations are examples of Fredholm integral equations of the first kind and are thus ill posed. Two methods are described for solving the equations numerically and hence providing estimates of the molecular weight distribution. The first method involves expanding the distribution in terms of orthogonal polynomials whose coefficients are calculated from estimates of the moments of the distribution. In the second method the distribution is reconstructed by using matrix singular-value decomposition techniques combined with an approximant expressed as a sum of B-splines. The potential and practical limitations associated with the methods are illustrated by numerical results from a series of tests on four problems designed to represent distributions with different modal properties.
    Additional Material: 5 Ill.
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    A structural model for high-modulus polyethylene derived from entanglement concepts (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 165-188 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Starting from the concept that the entanglement network is a controlling factor in polymer deformation, a molecularly based model has been constructed for polyethylene, drawn or extruded to high extension ratios λ. It predicts the experimentally observed form of the increase of Young's modulus E with λ: E-1 = B + Cλ-2. The model structure consists of imperfect crystalline microfibrils 10-30 nm in diameter and length αλ2, about 1 μm at λ = 30. The microfibrils terminate at clusters of entanglements, and are embedded in a matrix of low modulus. This structure is very similar to that derived from solution-grown shish-kebab material. Available melting-point data for highly extended material fit the structural model well.
    Additional Material: 11 Ill.
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    Concentrated solutions of polydisperse rodlike polymers in the isotropic and lyotropic liquid-crystalline phases. II. Model simulation of the dielectric relaxation behavior of poly(n-alkylisocyanates) in toluene and comparison with experimental results (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 213-231 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A simulation has been made of the dielectric relaxation behavior of poly(n-hexylisocyanate) in solution covering the isotropic, biphasic, and anisotropic ranges. The simulation incorporates the Flory-Abe statistical mechanical theory for the phase behavior of rodlike macromolecules in solution and the Warchol, Vaughan, Wang, and Pecora theory for the dynamics of a rodlike molecule in a virtual cone prescribed by the neighboring molecules. It is shown that asymmetric Gaussian, Gaussian, or Poisson distributions of molecular weight do not lead to dielectric behavior of the type observed experimentally by Moscicki, Williams, and Aharoni but addition of a high-molecular-weight “tail” to such distributions and taking account of the dependence of relaxation time on molecular length gives a simulation of the dielectric increment Δε, the loss maximum ε″m, and frequency of maximum loss fm, which vary with polymer concentration in a manner entirely consistent with the experimental data.
    Additional Material: 16 Ill.
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    Photon correlation spectroscopy of polystyrene as a function of temperature and pressure (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 605-611 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Photon correlation spectroscopy is employed to study the slowly relaxing density and anisotropy fluctuations in bulk atactic polystyrene as a function of temperature from 100 to 160°C and pressure from 1 to 1330 bar. The light-scattering relaxation function is well described by the empirical function φ(t) = exp[-(t/τ)β], where for polystyrene β = 0.34. The average relaxation time is determined at each temperature and pressure according to 〈τ〉 = (τ/β)Γ(1/β) where Γ(x) is the gamma function. The data can be described by the empirical relation 〈τ〉 = 〈τ〉0 exp[(A + BP)/R(T - T0)] where R is the gas constant and T0 is the ideal glass transition temperature. The empirical constant A/R is in good agreement with that determined from the viscosity or the dielectric relaxation data (1934 K). The empirical constant B can be interpreted as the activation volume for the fundamental unit involved in the relaxation and is found to be comparable to one styrene subunit (100 mL/mol). The quantity B appears to be a weak function of temperature. The use of pressure as a tool in the study of light scattering near the glass transition now has been established.
    Additional Material: 3 Ill.
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    Thermal annealing of doubly oriented nylon 11 in contact with formic acid (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 625-645 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The most striking feature of the mechanism of thermal annealing of doubly oriented samples of low-density polyethylene (LDPE) and probably of high-density polyethylene (HDPE) is a progressive tilt of lamellar crystals around their crystallographic b axis. Such a rotation does not occur on thermal annealing in doubly oriented nylons. However, this rotation mechanism occurs during the thermal annealing of doubly oriented samples of nylon 11 in contact with a solvent below its dissolution temperature. As for oriented samples of polyethylene (PE), a correlation between the changes of macroscopic dimensions and long spacing obtained from the small-angle x-ray pattern is difficult to establish. In doubly oriented samples of nylon 11, the basal faces of the lamellar crystals are parallel to the a axis of the unit cell. Nevertheless, simple Miller indices cannot be assigned to the basal planes of the lamellae. On thermal annealing in formic acid, the basal planes of the lamellar crystals are, in some cases, parallel to (00l) planes. Annealing in formic acid at room temperature induces a phase transition: the chain c axis remains oriented along the rolling direction and the (00l) planes become parallel to the limiting planes of the lamellar crystals. Bulk doubly oriented samples of nylon 11 annealed in formic acid just below the “dissolution temperature” have the same texture of orientation as filter mats of single crystals grown from dilute solution; moreover, as these bulk specimens remain doubly oriented, they can be used for further physicochemical investigations. The usual interpretation of the small-angle x-ray pattern is also discussed on the basis of the results reported in this paper.
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    Optical absorption spectrum of PMMA via laser calorimetry (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 647-655 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The optical absorption spectrum of poly(methyl methacrylate) (PMMA) has been obtained in the wavelength range 570-780 nm via laser calorimetry (employing a dye laser source). Because of the low thermal conductivity of PMMA, the complete solution to the heat conduction equation (carried out numerically) was required in the analysis of the data. At the wavelength of minimum absorption (near 647 nm), the absorption coefficient had the value 153 dB/km.
    Additional Material: 6 Ill.
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    Thermal expansion of oriented poly(methyl methacrylate) (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 657-665 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal expansivities along (α∥) and perpendicular (α⊥) to the draw direction of poly(methyl methacrylate) (PMMA) with extrusion draw ratios 1 ≤ λ ≤ 4 have been measured between 150 and 298 K. As λ was increased from 1 to 4, α∥ decreased 2-3 times, whereas α⊥ increased only 20-35%. The orientation function f calculated from thermal expansivity using the aggregate model is found to change linearly with birefringence, indicating that each property provides a sensitive measure of molecular orientation. For PMMA, however, only thermal expansivity can give an absolute f, with results at 150 K in reasonable agreement with previous studies using other techniques. At higher temperature, i.e., above ambient, PMMA side-group motions are excited, expanding volume, and calculations based on the aggregate model may not be valid.
    Additional Material: 6 Ill.
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    Preoriented poly(ethylene terephthalate) yarns: Influence of the gauche-trans transformation on crystallization (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 717-723 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Effects of macromolecular orientation on the crystallization of preoriented poly(ethylene terephthalate) filaments were studied. Infrared spectrophotometry and differential scanning calorimetry analyses showed that macromolecular segments in the trans conformation begin to crystallize below the glass transition temperature. Since filaments prepared by stretching at room temperature have different degrees of orientation, it is possible to evidence correlations between crystallization from an anisotropic matrix and the resulting morphology.
    Additional Material: 5 Ill.
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    Localized volume deficiencies as an effect of spherulite growth. I. The two-dimensional case (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1299-1312 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two-dimensional spherulite growth leads to the encirclement of regions of molten polymer in a polymer film. On further crystallization localized volume defects arise, resulting in thin spots in the film. Since this effect lowers the mechanical strength of films, we call these volume defects “weak spots.” A computer program is developed to evaluate the number, size, and shape of such volume defects for athermal, thermal, and mixed modes of primary nucleation of spherulites. It is shown that the total area of weak spots exceeds 10% of the sample area for all types of nucleation studied. The largest weak spots arise in samples crystallized via athermal and mixed nucleation; their size is of the same order as that of an average spherulite. Formation of weak spots is observed in thin films of poly(ethylene oxide) and poly(methylene oxide). The disadvantageous role of weak spots is confirmed by observation of electric breakdown occurring preferentially in weak spots in polypropylene films.
    Additional Material: 10 Ill.
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    Thermoluminescence from extended-chain crystals of polyethylene (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1347-1356 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermoluminescence (TL) has been observed in γ-irradiated extended-chain crystals of polyethylene above room temperature. The TL curve, which exhibits four peaks at 50, 90, 120, and 140°C, is different from that given by folded-chain crystals, in both shape and intensity. In particular, a shape, strong glow peak is observed at 140°C, corresponding to the melting temperature of the extended chain crystals. These results are discussed in relation to independent measurements by differential scanning calorimetry and electron spin resonance.
    Additional Material: 10 Ill.
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    Localized volume deficiencies as an effect of spherulite growth. II. The three-dimensional case (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1313-1322 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: As in the two-dimensional case, the density change due to crystallization leads to a buildup of internal strain in some regions of a polymer melt occluded by growing spherulites. The occluded parts of the sample are called “weak spots.” Computer simulation of spherulite growth in bulk samples shows that the largest weak spots have the size of an average spherulite. The total volumes of weak spots are 0.47, 0.094, and 0.119% of the sample for athermal, thermal, and mixed primary nucleation, respectively. The weak spots in the bulk material exhibit distance correlation. Within weak spots, internal strain is released (Raman spectroscopy), and holes develop. Polypropylene bulk spherulite samples contain holes distinctly visible under a microscope with infrared optics and illumination. The number of visible holes is in agreement with the computer prediction. The increase of impact strength with decreasing spherulite size is explained in terms of changes in the number and size of weak spots.
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    Ab initio calculation of polyethylene deformation including electron correlation effects (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1341-1346 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The longitudinal acoustic elastic modulus of polyethylene has been calculated with the aid of the ab initio crystal orbital method applying corrections also for electronic correlation effects. The basis set and correlation dependence of the elastic modulus have been investigated. The best theoretical value of 305 GPa of this modulus is in reasonable agreement with the published experimental values. At an elongation of ca. 0.1 the deviation from Hooke's law is found to be substantial.
    Additional Material: 3 Tab.
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    Effect of amorphous sequences on the longitudinal acoustic modes in partially crystalline polymers. I. Transfer matrix method (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1357-1380 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A novel theoretical scheme is developed which enables the determination of the LAM-like vibrations of polymer chains made up of crystalline and amorphous parts as they occur in partially crystalline structures. The boundary conditions effective at the junction points are formulated in terms of the compliances of the associated amorphous sequences. These compliances can be derived from their eigenfrequencies and eigenvectors in a disconnected state. The treatment uses a matrix formalism which can be extended to include bending and torsional motions in a general state of vibration of the crystalline stem. A first numerical example demonstrates that the LA mode of a crystalline stem can be strongly perturbed by the coupling to the adjacent amorphous sequences. Interpretation of frequencies and line shapes of observed LA modes should always include these coupling effects; their neglect can lead to considerable errors.
    Additional Material: 10 Ill.
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    EXAFS studies of nickel nafion ionomers (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1389-1401 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Nafion membranes neutralized with Ni2+ have been examined by extended x-ray absorption fine-structure (EXAFS) and x-ray absorption near-edge-structure (XANES) spectroscopy. The results indicate that in both the dry and water-soaked membranes, the nickel is in an octahedral site with six oxygen atoms as nearest neighbors. The degree of disorder in the Ni—O distance is comparable to that in ionic crystals in both the dry and hydrated materials. A contribution from a second shell of neighbors is very weak in the dry samples but, surprisingly, this contribution is strongly accentuated in the hydrated membranes. The data indicate that this contribution is due to neighboring Ni2+ cations. Thus the water absorption seems to enhance the local ordering of the cation environment. The local structure does not depend strongly on the concentration of ionic groups in the materials.
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    Relationship between the cohesive strength and the tack of elastomers (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1415-1425 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The autohesion (tack) and cohesion of a random styrene-butadiene elastomer have been examined as a function of test temperature and speed using a T-peel geometry. Both properties have been reduced to a single master curve by horizontally shifting the data with the same set of shift factors. The cohesive strength increases with increasing reduced test rate RaT and appears to approach a plateau at the highest rates. Tack also increases with RaT but decreases abruptly at a critical rate and peeling the occurs in a stick-slip fashion. Tack again increases at sufficiently high test rates. In the range of rates where tack is maximized, its value is essentially the same as its cohesive strength. Above or below this range, tack is substantially less than the elastomer's cohesive strength. Mechanisms are proposed to explain why relative tack (i.e., tack divided by cohesive strength) is not a simple measure of the extent of completion of a tack bond and may indeed be equal to one in spite of incomplete tack bond formation.
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    Retardation of spherulitic growth rate in the crystallization of isotactic polystyrene due to the presence of nucleant (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1403-1413 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Although the rate of heterogeneous nucleation of crystallization in isotactic polystyrene, as studied by photomicroscopy, is markedly increased by addition of fine-particle silica, the rate of subsequent radial growth of spherulites formed is diminished. The latter observation is rationalized on the basis of a modified Hoffman-Lauritzen treatment wherein the nucleant is depicted as a quasicrosslink which impedes the transport of polymer segments.
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    Properties of semidilute polymer solutions: Investigation of an optically labeled three-component system (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1381-1388 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A three-component system containing a polymer (2), a good solvent (1) for that polymer, and a second polymer (3) that is compatible with component (2) and isorefractive with the solvent (1) has been studied by static and dynamic light-scattering methods. In concentrated toluene (1) solutions of poly(vinyl methyl ether) (3), where appreciable chain overlap occurs and excluded-volume effects are reduced, polystyrene (2) may be studied in the dilute-solution limit. Consequently, these light-scattering measurements provide an explicit measure of both thermodynamic and hydrodynamic changes that occur as the total polymer concentration is increased from dilute to concentrated solution. Precise numerical coefficients, correct scaling exponents, the radius of gyration, and the effective hydrodynamic radius can be measured directly along with the observation of long-wave single-chain reptation motions and short-range cooperative motions in semidilute and concentrated solutions.
    Additional Material: 4 Ill.
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    Thermal expansivity of oriented poly(ethylene terephthalate) (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1427-1438 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The linear thermal expansivity of poly(ethylene terephthalate) extruded at 50 and 90°C to extrusion ratios λ of 1-4.8 has been measured between 120 and 300 K. With increasing λ, the expansivity along the extrusion direction (α∥) decreases sharply, while that in the transverse direction (α⊥) shows a slight increase. For λ 〈 3, the large drop in α∥ and the accompanying increase in the axial Young's modulus E∥ can be ascribed to chain alignment in the crystalline regions and to an increase in number and tautness of intercrystalline tie chains. At higher λ, however, the crystalline orientation apparently becomes saturated, so that taut tie molecules are solely responsible for further changes in both α∥ and E∥. On the other hand, α⊥ is mainly determined by crystalline orientation for all λ, thus showing very little increase at large λ. For the highly oriented samples (λ ≥ 3), the Takayanagi model provides a reasonable description of the behavior of α∥ and α⊥.
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    An analysis of local flow effects in flow-induced orientation and crystallization (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1473-1492 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An analysis is presented of the effects of external flow kinematics on the so-called local flow in seeded, flow-induced crystallization and orientation. The flow field around a growing crystal or nucleation seed is modelled by the Stokes flow equations past a prolate ellipsoid of high aspect ratio. Exact solutions for various flow kinematics, worked out elsewhere by the singularity method, are applied here to the analysis of local gradients. The results show that along the symmetry axis of the spheroid, the extensional gradients which result for various free-stream velocity fields are primarily the result of the constant-velocity free-stream component. However, free-stream, extensional flow can significantly enhance the region of such high gradients. Along the symmetry plane of the spheroid, primarily shearing gradients result, with small extensional gradients occurring when the free-stream flow has extensional components. Results of chain extension and birefringence calculations are also presented and discussed.
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    Inclusion of mobile crosslinks and lateral crystallite growth in the theory of stress-induced crystallizationCorrected proofs received October 18, 1982 (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 45-53 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The theory of stress-induced crystallization is broadened to include a reshuffling of crosslink positions as a result of changing sizes of crystalline domains and multiple crystallites of varying lateral dimensions (i.e., lateral growth). A continuous state of equilibrium throughout the amorphous component of the stretched network is postulated and, consequently, effected by requiring crosslinks to anchor about their most probable locations, which vary continuously as crystallization changes. Such features incorporated into Flory's model of stress-induced crystallization broaden its theoretical base, placing it on a stronger, more realistic foundation.
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    Crystallization under stress: A theory of fibrillar crystallizationCorrected proofs received October 18, 1982 (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 55-63 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A theory of crystallization in stretched polymer networks is developed. In it, four principal features are incorporated: (i) crosslinks are displaced by growing crystallites, (ii) network chains are constrained to positions compatible with fixed sample shape and volume, (iii) some network chains remain amorphous, and (iv) the relative direction of a chain through a crystallite may not be the same for all chains. The derived network force exhibits a V or U shape with changing temperature in the crystallization zone that is a close replica of the behavior of gutta percha networks. Postulates of fibrillar-lamellar transitions are not introduced into the calculations.
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    Structure-property relationships in polycaprolactone-polyurethanes (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 65-95 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The structure-property relationships of polycaprolactone-based segmented polyurethanes were studied using differential scanning calorimetry (DSC), small-angle x-ray scattering (SAXS), wide-angle x-ray diffraction (WAXD), dynamic mechanical, and stress-strain testing. The materials studied varied in hard-segment type [4,4′-diphenylmethane diisocyanate/butanediol (MDI/BD) or 4,4′-dicyclohexyl methane diisocyanate/butanediol (H12MDI/BD)], soft-segment molecular weight (830 or 2000 MW polycaprolactone), hard-segment content (23-77% by weight), and thermal history. The materials with aromatic (MDI/BD) hard segments had semicrystalline hard-segment domains, while the materials with aliphatic (H12MDI/BD) hard segment had mostly amorphous domains. Materials with the shorter polycaprolactone soft segment (830 MW) exhibited thermal and mechanical behavior which indicated a considerable degree of hard- and soft-segment compatibility. The materials which contained a 2000-MW polycaprolactone soft segment exhibited better-defined microphase separation. SAXS was used to characterize the microphase structure of each system. The effects of hard-segment content and soft-segment molecular weight were similar for the aromatic (MDI) and aliphatic (H12MDI) hard-segment-based block copolymers. Changing the hard segment from aromatic to aliphatic gave materials with larger interfacial area and slightly higher tensile strength. A range of morphologies between isolated hard domains in a rubbery matrix and isolated rubbery domains in a hard matrix was observed.
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    Radiation chemistry of polybutadiene and butadiene-styrene block copolymers. II. Kinetics and mechanisms of free-radical decay reactions (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 111-121 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The decay of free radicals produced in polybutadiene, polystyrene, and block copolymers of butadiene and styrene by γ irradiation at 77 K has been studied at -110°C in the case of polybutadiene and at -95°C for the other samples. The free-radical decay rate is best interpreted in terms of an equation based on a second-order decay mechanism of a fraction of the free radicals decaying in the presence of other nondecaying free radicals. Hydrogen gas accelerates the free-radical decay. Increase of radiation dose increases the fraction of the radicals that decay, while increase of the fraction of styrene segments decreases the decaying fraction. In pure polybutadiene the higher the cis content, the greater fraction of decaying free radicals, but the second-order decay constant is less in the high-cis-content polybutadiene and is also less at the higher dose, probably owing to the hindrance of the radiation-produced crosslinks on the free-radical decay. The decrease of the second-order constant with increase of dose is also true for all the block copolymers studied.
    Additional Material: 6 Ill.
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    Interdependence of motional processes in polymers: correlation functions for nmr relaxationCorrected proofs received November 22, 1982 (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 263-274 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The roles of both anisotropic motion and the interdependence of multiple motions in leading to nonexponential correlation functions for NMR relaxation data are explored. A motional model is developed in which rotational motions of segments of various lengths are controlled by the formation and disappearance of a suitable conformation. Such a model gives correlation functions which can be made, through adjustment of parameters, to be almost identical to correlation functions from other, quite different, models. The ability of NMR relaxation data to identify unique motional models is thus questioned.
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    Particle morphology in the radiation-induced heterophase polymerization of vinyl chloride with solvent added in small amounts (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 251-262 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Investigations were carried out on the polymer particle morphology obtained in the early stages of radiation-induced bulk polymerization of vinyl chloride with solvent added in small amounts over the temperature range of -10 to 70°C under quiescent conditions. At low temperatures, when the polymerization is carried out in the absence of solvent, there is flocculation of irregular aggregates of two types depending on polymerization conditions: (i) small primary particles that remain finely dispersed and (ii) large flocs that undergo rapid sedimentation. By addition of increasing amounts of solvent a gradual change towards single small spherical particles that remain finely dispersed is obtained. With more than 3% w/w THF, spherical particles in latexlike dispersions are obtained in polymerizations at -10 and 22.8°C, and show a small change in size with increasing amounts of THF. In the high-temperature range, 50-70°C, where spherical particles can be obtained in the absence of solvent, no significant changes are produced by addition of THF. The results are discussed in the terms of a marked increase in particle plasticization by the solvent, enabling the coalescence of flocculated particles of small size to occur also in polymerization at low temperature.
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    Polymorphic structure and physical properties of the polyester/ether poly(ethylene-1,2-diphenoxyethane-p,p′ -dicarboxylate) (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 275-284 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: X-ray diffraction studies of fibers of the polyester/ether poly(ethylene-1,2-diphenoxyethane-p,p′ -dicarboxylate) (PEET) produced by high-speed melt spinning show the existence of two polymorphic forms, designated α and β, in the solid state. The α form is obtained by annealing filaments melt spun at takeup speeds below 3000 m/min and is also found in samples crystallized from the melt and from dilute solutions. The α form has a monoclinic unit cell with dimensions a = 7.83, b = 10.33, c = 18.68 Å, and β = 83.1°. The equilibrium melting temperature and heat of fusion of the α form are 288.3°C and 19.1 cal/g, respectively. The β form predominates in highly oriented filaments obtained at takeup velocities above 6000 m/min. The unit cell is orthorhombic with dimensions a = 7.28, b = 5.65, and c = 18.64 Å. The β form does not transform to the α form on annealing.
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    A Raman-spectroscopic study of solution-crystallized polyethylenes (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 285-294 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An analysis of the Raman internal modes of dilute-solution-crystallized homopolymers and co-polymers of ethylene has been made, similar to the work previously reported for the bulk-crystallized polymers. The crystallite structure can be described in terms of the relative amounts of the crystalline orthorhombic phase, the liquidlike amorphous phase, and the interfacial region. These quantities change with the molecular constitution of the chains and the crystallization conditions. The level of crystallinity decreases significantly with increasing counit content as would be expected. In addition, an appreciable interfacial structure develops in copolymers as compared with the homopolymers. A possible relationship between the interfacial content and the relaxation transitions in polyethylene is discussed.
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    The heat of fusion of poly(ethylene terephthalate) (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 295-299 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: By use of the Clapeyron equation for the dependence of the melting point on pressure, the heat of fusion was found to be 32.5 cal/g, in good agreement with values determined by other methods. An equation for the dependence of the melting point on the degree of polymerization gave a heat of fusion of 27.6 cal/g when applied to hydroxyl-terminated oligomers. This simple relation applied all the way down to the smallest member of the series, di(hydroxy ethyl) terephthalate.
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    Photon correlation spectroscopy of polymer solutions (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 807-820 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A polynomial subdistribution method for analyzing the correlation profile in photon correlation spectroscopy of polymer solutions is described. This method generates a continuous distribution function from the measured photoelectron time-correlation function, which can be related to particle size or molecular weight distribution of solute. The method is tested using simulated data for unimodal and bimodal distributions and compared with cumulant and histogram methods, respectively. The polynomial subdistribution method has an advantage in that it not only generates a continuous distribution curve but also works well for bimodal distributions whose peaks are close together.
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    One-dimensional models of polymer dynamics. II. A dashpot-spring model (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 787-806 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The assumption of Clark and Zimm that coupled dashpots and springs can be used to model the dynamics of polymer molecules is here applied to a model different from that of Clark and Zimm. The precise differences are given in the preceding paper. The dielectric relaxation spectrum of the model is computed in time and frequency domains. The relaxation spectrum can be fitted reasonably well by the empirical Williams-Watts and Havriliak-Negami functions. The best-fit Williams-Watts and Havriliak-Negami parameters are given as functions of the parameters of the model. The model is compared with several related models found in the literature and possible interpretations are given.
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    The melt anisotropy of ultrahigh-molecular-weight polyethylene (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 821-830 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the course of melt-flow crystallization studies with ultrahigh-molecular-weight polyethylene (UHMWPE), we observed that the melt of UHMWPE is highly anisotropic above its equilibrium melting point and has a tendency to fibrillate. An examination of the melt anisotropy of UHMWPE by optical, Thermal, and x-ray analysis indicates that the melt anisotropy persists at 345°C, i.e., the temperature at which the polymer degrades under nitrogen, and appears similar to a smectic liquid-crystalline phase.
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    Ionic conductivity of hybrid films composed of polyacrylonitrile, ethylene carbonate, and LiClO4 (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 939-948 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The electrical conductivity of hybrid films consisting of polyacrylonitrile (PAN), ethylene carbonate (EC), and LiClO4 was investigated. In these films, EC and LiClO4 are found to be molecularly dispersed in PAN, forming solid solutions over a wide composition range. The ionic character of the electrical conductivity is demonstrated. The conductivity is not correlated with the content of LiClO4 or of PAN, but primarily with the mole ratio [EC]/[LiClO4] in the films. An increase in the [EC]/[LiClO4] ratio enhances the conductivity. When the ratio is about 2, the conductivity attains 10-4-10-5 S cm-1 at 25°C. This change in conductivity results from a change in carrier mobility. PAN makes the films solid without decreasing the carrier mobility. In the hybrid films, the carrier mobility and the macroscopic viscosity are not related by Walden's rule. The high conductivity is due to regions in the film characterized by a low microscopic viscosity. This is determined by the mole ratio [EC]/[LiClO4] and largely controls the carrier mobility.
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    Radiation chemistry of linear low-density polyethylene. I. Gel formation and unsaturation effects (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 949-956 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Quenched and annealed samples of linear low-density polyethylene (LLDPE) were irradiated with 60Co γ rays in vacuo at room temperature. The data follow rather accurately Charlesby's equation s = k/r, where s is the soluble fraction, r the dose, and k a constant from which G(X), the G-value for crosslinks, was calculated. Crosslinking in the LLDPE is about twice as extensive at equal doses as in LHDPE. Production of vinylene unsaturation was approximately the same in the two types of polyethylene.
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    Radiation chemistry of linear low-density polyethylene. II. Kinetics of alkyl and allyl free-radical decay reactions (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 957-967 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Quenched and annealed samples of linear low-density polyethylene (LLDPE) were γ irradiated in vacuo at 77 K; the kinetics of the alkyl free-radical decay reactions were studied at room temperature, and of the allyl free-radical reactions at 60, 70, and 80°C. The ESR signals saturate at a slightly higher microwave power in the LLDPE than in high-density polyethylene (HDPE), and the alkyl radicals start decaying at a lower temperature in the LLDPE than in the HDPE. As in the HDPE the decay of the alkyl free radicals at room temperature in the LLDPE follows the kinetic equation for two simultaneous first-order reactions with the fraction of the faster-decaying component being slightly greater in the quenched than in the annealed samples. In the case of the allyl free radicals the decay at 60°C follows the equation based on one fraction of the radicals decaying according to second-order kinetics in the presence of other nondecaying radicals. At higher temperatures the data are best understood in terms of a second-order rate equation with a continuously variable time-dependent rate constant as suggested by Hamill and Funabashi.
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    Small-angle x-ray scattering studies of crazed glassy polymers (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 969-982 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A small-angle x-ray scattering (SAXS) study of the relaxed craze structure in polystyrene was performed using the Oak Ridge National Laboratory 10-m SAXS facility. Coupled with known results from transmission electron microscopy studies, the SAXS patterns can be interpreted as scattering from an open-cell foam with void spaces interspersed among the fibrils. Results have shown the scattering centers in crazed polystyrene can be modeled as cylinders the axes of symmetry of which are parallel to the tensile axes. Scattering centers are bimodal in their size distribution, with aspect ratios of 1.0 and 2.6. Crazes in lower-molecular-weight polystyrene have more and larger scattering centers than crazes in higher-molecular-weight polystyrene, while variations in strain rate and test temperature during craze formation have no effect on the relaxed craze morphology. A comparison of SAXS patterns from polystyrene and polycarbonate indicates that the morphologies of their respective crazes are significantly different.
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    An investigation of the compatibility and morphology of semicrystalline poly(ε-caprolactone)-poly(vinyl chloride) blends (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 999-1010 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends of poly(ε-caprolactone) (PCL) and poly(vinyl chloride) (PVC) were investigated at concentrations of PCL greater than 50 wt % using purified materials. For these concentrations, PCL partially crystallizes with degrees of crystallinity ranging from 50% for pure PCL to 〈 10% for the 50% mixture. Small-angle x-ray scattering was used to characterize the resultant morphologies. Model calculations for the interference functions and for the integrated scattering indicate that PVC is incorporated between the PCL lamellae and that the two polymers form a homogeneous mixture in the amorphous phase. These results were compared to previous results on the same system using the identical technique. Purification of the two homopolymers proved to play a critical role in the overall mixing characteristics of PVC and PCL
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    The swelling interface number as a criterion for prediction of diffusional solute release mechanisms in swellable polymers (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 983-997 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: When a glassy polymer containing a uniformly dispersed solute is brought in contact with a penetrant, solute diffusion will be associated with the transport mechanism and penetration velocity of the penetrant in the polymer. Analysis and prediction of mechanisms of diffusional solute release may be obtained through a new dimensionless number, the swelling interface number, Sw, which compares the relative mobilities of the penetrant and the solute in the presence of macromolecular relaxations in the polymer. It is shown that a sufficient and necessary criterion for time-independent diffusional solute release rates from these swellable systems is that the Sw be smaller than 10-2. The swelling interface number Sw may be related to easily determined structural and thermodynamic parameters of the solute/polymer/penetrant system. Preliminary experimental results of dynamic water swelling of poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) and diffusional release of theophylline from initially glassy copolymers show that decreasing values of Sw are related to increased pseudo-case-II transport kinetics of the solute.
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    Friction coefficients in self-diffusion, velocity sedimentation, and mutual diffusion for poly(ethylene oxide) in aqueous solution (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1029-1039 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The concentration dependences of the friction coefficient(s) for poly(ethylene oxide) have been determined on well-defined fractions in dilute aqueous solution. Three independent techniques have been used: FT-pulsed field gradient NMR (self-diffusion), photon correlation spectrosccpy (mutual diffusion), and velocity sedimentation, in the concentration range 1-25 kg m-3. The results establish that, at a given concentration, the friction coefficient in self-diffusion is appreciably smaller than that operating in mutual diffusion and sedimentation; the friction coefficient in the latter processes are identical within experimental error.
    Additional Material: 9 Ill.
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    Electrostatic contribution to heat capacity of polyelectrolyte solutions (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1563-1566 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
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    A simple, cost-effective automatic capillary viscometer system (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1559-1562 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
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    Flow-induced crystallization by surface growth of polyethylene fibers (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1513-1526 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of experiments has been carried out investigating several features of the surface growth method for observing longitudinal growth of polyethylene fibers in Couette geometry. Attempts to obtain limiting steady-state takeup rates using a Teflon rotor were hampered by fiber breakage; however, maximum growth rates before breakage were found to be considerably higher than those observed in previous studies. Growth rates were also obtained using a static method, and for the Teflon rotor indicated above a critical concentration a linear growth rate equal to the stirrer velocity with rates essentially independent of temperature. With a silanized glass rotor, the same method gave much lower growth rates at comparable stirrer speeds and temperatures and showed a temperature dependence suggestive of a nucleation-controlled mechanism. The implications of these results for other studies of the mechanisms of growth by the surface method are also discussed.
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    Carbon-13 NMR spectra of solid chlorinated polymers (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1569-1572 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
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    Elastic modulus of syntactic foams (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1567-1568 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
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    Polymer single crystals of poly(4-hydroxybenzoate). I. Morphology (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1599-1609 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(4-hydroxybenzoate) was prepared from 4-acetoxybenzoic acid, 4-pivaloyloxybenzoic acid, and 4-trimethylsiloxy benzoyl chloride by condensation without the addition of a catalyst. Although various reaction conditions were used the products were always crystalline. The morphology of the as-polymerized crystals has been studied by transmission electron microscopy as a function of molecular weight and end-group type. It was possible to detect morphological features during the course of reaction from oligomers to polymer which enabled us to determine the mechanisms that are likely to control chain growth for different regimes of polymerization kinetics.
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    Studies on dilute solutions of rodlike macroions. I. Light scattering, densitometry, and cryoscopy (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1573-1597 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Total integrated and photon correlation light scattering have been used to study two samples of poly(1,4-phenylene-2,6-benzobisthiazole) (PBT) representing two methods of precipitation to recover the polymer from the polymerization solvent. Some details of the light-scattering instrument are given. It is found that the PBT sample is rodlike, with persistence length of at least 50 nm, but that the postpolymerization processing method influences the state of interchain aggregation. The data are augmented by measurements of freezing-point depression to estimate the degree of protonation of PBT in sulfuric acid, and by measurements of partial specific volume to provide an estimate for the geometric diameter of the chain in solution. The results show a degree of protonation of 2-4 protons per repeating unit, and partial specific volumes that are appreciably smaller than the specific volume determined for the polymers. Similar data and results are reported for poly(1,4-phenyl-ene-2,6-benzobisoxazole) and poly(1,4-phenylene terephthalamide).
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    Diffusion of iodine into PE and PET (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1635-1646 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We show that the Rutherford backscattering technique is very useful for studying the kinetics of diffusion processes in polymers. We have measured the diffusion of iodine into low-density polyethylene (LDPE) by optical absorbance and by Rutherford backscattering. The optical results appear to be normal, and show no electric field dependence, but the backscattering results reveal that this is misleading, because there is fast diffusion in the bulk accompanied by large surface concentrations of iodine. We have studied PET by the backscattering technique, and in this case the behavior corresponds to a weakly concentration-dependent diffusion coefficient with no observable surface effects. Neither set of results gives support to the domain theories of low-frequency electrical oscillation in these materials.
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    Polymer single crystals of poly(4-hydroxybenzoate). II. A contribution to crystal structure and polymorphismDedicated to Professor H.-J. Cantow on the occasion of his 60th birthday. (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1611-1633 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Electron diffraction has been used to investigate the structure of a wide range of as-polymerized crystals of poly(4-hydroxybenzoate) [systematic name: poly(1,4-oxybenzoyl)]. The chemical composition and the degree of polymerization (DP) have been varied and some samples have been thermally treated. At room temperature two crystalline modifications with orthorhombic unit cells coexist. The chains adopt a 21 helical conformation in both forms, but there are differences for oligomer and polymer crystals. Oligomers of low DP have an extended chain-conformation, whereas in polymers a shortening of the repeat distance along the chain is observed as a function of both the DP and the crystallization conditions. From the most extensive data sets we have derived the lattice parameters a = 7.52, b = 5.70, and c = 12.49 Å for polymer crystals of phase I, and the subcell parameters for oligomer crystals of phase II a = 3.77, b = 11.06, and c = 12.89 Å. Both phases contain two chains per unit cell. In addition to modifications I and II several defect structures exist the unit cells of which contain more than two chains. At temperatures which depend on the degree of polymerization, a phase transition to a third modification takes place. The large difference between the densities of phase III as compared to both phase I and II suggests that torsional degrees of freedom exist in phase III which allow a certain mobility of the phenyl and ester groups. This mobility enables the end groups of adjacent layers in interlamellar regions of oligomer crystals to undergo transesterification reactions and therefore to increase the molecular weight of the samples.
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    C-13 NMR analysis of polystyrene from low-molecular-weight model compounds (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1667-1674 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Methylene and phenyl C1 carbon signals of polystyrene are assigned on the basis of the signal assignments of styrene oligomers. Polystyrenes prepared with benzoyl peroxide, n-butyllithium, and trifluoroboron etherate catalysts have random distributions with probabilities of racemic dyads of 0.54, 0.56, and 0.45, respectively.
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    The effect of dye sorption on electromechanical properties in sodium poly(L-glutamate) (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1661-1665 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Piezoelectric constant, Young's elastic modulus, and dielectric constant of undyed and dyed films of poly(L-glutamate) were measured at 10 Hz over the temperature range -120 to 120°C. The temperature of the maximum in -d″14 shifts toward higher temperature up to 0.6 mg/g polymer of dye uptake and then shifts toward lower temperature by further dye sorption. The variation of the piezoelectric modulus was interpreted by the change of mobility of impurity ions in the sample.
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    Existence of a distribution of hole-trap activation energies in FEP-Teflon (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1691-1701 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: When FEP-Teflon samples are electron irradiated at room temperature in open circuit and stored in that state for varying times following the end of irradiation, the temperature of the first current peak of the short-circuit TSC plot increases with increasing storage time. A new model is presented to explain this phenomenon, its main features being (i) a quasicontinuous distribution of hole-trap activation energies, the “center of mass” of the trapped hole population moving toward the deeper end of the distribution during the storage time, and (ii) an electron/hole recombination coefficient much smaller than that implied in an earlier model. It is shown that the assumption of a single dominant type of hole trap implies an unrealistically large frequency factor.
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    Thermotropic homopolyesters. III. Preparation and properties of polymers based on 4′-hydroxyphenyl-4-hydroxycinnamate (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1851-1872 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Low-molecular-weight 4′-acetoxyphenyl-4-acetoxyoinnamate, as well as several polyesters synthesized from this monomer and aliphatic dibasic acids, exhibit thermotropic nematic phases. DSC heating curves for all of the polymers exhibit multiple transitions. The amount of crystallinity of these polymers at room temperature is small and the degree of order along the chain axis in the crystalline phase is poor. For the lower homologues the nematic phase exists over a broad temperature range of approximately 100°C. The polyester from chiral (+)-3-methyl adipate forms a thermotropic cholesteric phase. Both the diacetoxy monomer and azelate polymers of low molecular weight adopt the homeotropic texture on glass slides, but with increasing molecular weight the planar texture becomes preferred. Investigation of the effects of electric fields in the conduction regime upon the nematic phase of the diacetoxy monomer revealed that Williams domains are formed only with difficulty. In most cases, a stationary pattern appeared instead. At higher voltage the dynamic scattering mode (DSM) was obtained, and above this a field-induced transition to the isotropic phase. The azelate polyesters exhibited Williams domains and the DSM in the conduction regime. The formation time for Williams domains was fairly short for polymers having ηinh 〈 0.44 dL/g, but increased to 80 min when ηinh = 0.68 dL/g. The DSM was only observed for polymers having ηinh 〈 0.61 dL/g. For these polymers the critical frequency separating the conduction and dielectric regimes exhibits a stronger temperature dependence than that of low-molecular-weight nematogens. A new instability pattern is reported for the azelate polyesters in the dielectric regime.
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    Photon correlation spectroscopy of polymers in the glassy state (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1897-1902 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Photon correlation spectroscopy has proven to be a very useful technique for studying slowly relaxing density and optical anisotropy fluctuations in bulk polymers near the glass transition. When some of the fluctuations achieve relaxation times much longer than the typical averaging time for the intensity autocorrelation function (104 s), the result must be treated in the partially heterodyned limit. Also, when the sample is near the glass transition but not at equilibrium the correlation function is not stationary in time because the system is relaxing as a whole toward the equilibrium state. The above effects are discussed theoretically and demonstrated experimentally in polystyrene as a function of temperature and pressure. Light scattering with coherent excitation also fluctuates in space as well as in time (as shown in the accompanying paper). The consequences of this effect are discussed. When most of the intensity is associated with fluctuations whose relaxation times are very long in polystyrene, there is still a broad relaxation function evident. This is characteristic of a secondary relaxation process.
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    An analysis of the reflective component of small-angle X-ray scattering patterns from crazed polystyrene (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1913-1926 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An investigation of the reflective component of small-angle x-ray scattering patterns of polystyrene crazes is performed. It is shown that the strong streak parallel to the tensile axis consists predominantly of reflected radiation, while the remaining pattern is composed entirely of diffracted radiation. X-ray reflection off unparallel regions of crazes is discussed and the nature of the reflection is also considered in terms of collimation quality. An analysis methodology based on craze tip angular distribution is proposed.
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    Microstructure rearrangement during the heat-treatment of melt-drawn poly(ethylene terephthalate) fibers (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1927-1953 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Melt-spun poly(ethylene terephthalate) fibers were isothermally heat-treated at constant length. Microstructural changes occurring during the heat-treatment were monitored using specific gravity, wide-angle x-ray scattering (WAXS), small-angle x-ray scattering (SAXS), optical birefringence, and static mechanical testing. Major changes in the density of the most highly oriented fiber examined occurred in times below 100 ms. For less oriented fibers, the time scale for significant density change increases to the 1-10 s range. The course of birefringence increase approximates that of the density. WAXS measurements show that crystallinity develops at essentially constant crystal perfection, but that the orientation of the crystallites first decreases and then increases with time. SAXS results show development of a four-point pattern, the azimuthal angle of the lobes decreasing with initial orientation, with temperature, and with time. A streak transverse to the fiber axis develops more rapidly than do the lobes. A two-stage transformation process is envisaged, the first stage being the formation of defective crystal fibrils and the second being internal rearrangement of the fibrils to form more perfect crystallites, separated by more amorphous zones. Changes in the crystallite orientation are related to constraints of the noncrystalline material on the crystallites.
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    The effect of temperature on the infrared spectra of poly(ethylene terephthalate) (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 2067-2083 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reversible and irreversible spectral changes are observed on heating of solvent-cast films of poly(ethylene terephthalate) (PET) between 30 and 230°C. The irreversible changes are due to the gauche-trans isomerization of the ethylene glycol segments and the corresponding changes in the symmetry and resonance characteristics of the aromatic rings. On the other hand, there are thermally reversible spectral changes. These reversible effects are primarily observed for the modes of the aromatic ring and the trans ethylene glycol segment. These reversible spectral changes include intensity variations and frequency shifts and are found to be linearly dependent on the measurement temperature. These reversible changes arise from changes in intermolecular and intramolecular forces as the temperature changes.
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    Modeling the structure of chain-molecule liquids: A computer simulation of the n-alkanes C8-C30 (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 2379-2387 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Computer models of a series of liquid n-alkanes were generated, allowing for continuous variation of torsion angles and of atomic positions. Torsional and intramolecular and intermolecular non-bonded potentials were introduced. Calculated fractions of gauche bonds are slightly higher than those calculated from a rotational isomeric state model. Calculated radial distribution functions exhibit peaks in good agreement with experimental data. No directional correlation between chains is found, except at very short distances. Calculated end-to-end distances and radii of gyration indicate random coil conformations. These results are unaffected by extension of the range of interaction to the attractive region and by variations of temperature and density.
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    Study of light-scattering changes induced in tRNA solutions by a strong optical field of picosecond pulses (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 2465-2471 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Changes in the light-scattering components (λ = 0.53 μm) induced by a strong picosecond optical field (λ = 1.06 μm) applied to macromolecular transfer ribonucleic acid (tRNA) solutions were studied. Two beams were polarized vertically, and the intensity of the vertical and horizontal components of the light (λ = 0.53 μm) scattered at an angle of 90° were measured. The electric field of the strong 30-ps laser pulse was 5.0 × 103 esu cgs. The experimentally determined changes allowed for calculation of the mean third-order optical polarizability c, and its anisotropy δc. The measurements were performed in three different solutions: salt free, with magnesium ions, and without magnesium ions. Changes in tRNA structure reflected in changes of nonlinear light scattering, third-order optical polarizability, and its anisotropy were observed.
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    Birefringence and glass transition temperatures of poly(diethylene glycol terephthalate) networks (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 2473-2482 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of polymer networks were prepared by trifunctionally endlinking poly(diethylene glycol terephthalate). The elastomeric properties of these materials were studied at constant temperature using experiments that involve both the elastic force and birefringence. Whereas the stress-strain isotherms show an anomalous increase in the modulus at very high elongation ratios, a downturn appears in the birefringence-strain isotherms at the same extensibilities. These results suggest that the upturn that appears in the force should be attributed to maximum chain extensibility rather than to strain-induced crystallization. A variety of additional thermoelastic experiments were carried out on these networks, to elucidate the dependence of the glass transition temperature on strain. It was found that for the elongation ratios at which the networks exhibit Gaussian behavior, the free-volume effects on the glass transition temperature Tg (decreasing Tg with increasing free volume) offset the conformational effects (increasing Tg with decreasing entropy). However, the contrary occurs in the region where the stress increases anomalously with increasing strain.
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    Line broadening in the 13C NMR spectra of bulk polymers above Tg (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 2551-2559 
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    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of magic-angle sample spinning (MAS), high-power decoupling, and resonance frequency on the 13C NMR linewidths of bulk polyisobutylene and bulk trans-polybutadiene are examined. The 13C linewidths increase with resonance frequency, are unaffected by high-power decoupling, and are reduced to different extents by MAS. The dominant contribution of the natural linewidth of the polyisobutylene lines is confirmed. The two carbons of trans-polybutadiene have approximately equal linewidths under all conditions, a result that eliminates residual chemical shift anisotropy as a major contributor to the linewidths. The large reduction of the trans-polybutadiene linewidths with MAS, coupled with the above result, suggests that microscopic variation of magnetic susceptibility is the major factor for this semicrystalline polymer. Cross-polarized 13C spectra of trans-polybutadiene were obtained with and without MAS. With MAS, resonances due to the crystalline and amorphous components were resolved. The principal components of the chemical shift tensor of the vinylene carbons were obtained from the spectrum without MAS.
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  • 95
    Electronic Resource
    Electronic Resource
    A theoretical investigation of chain packing and electronic band structure of the rigid-rod polymer trans-poly(p-phenylene benzobisthiazole) in the crystalline state (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 2543-2549 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The extended Hückel method was employed to calculate electronic band structures in trans-poly(p-phenylene benzobisthiazole) (trans-PBT) in an attempt to elucidate the packing and electronic properties of these chains in the crystalline state. The unit-cell energies thus calculated indicate that the most stable arrangement for trans-PBT corresponds to the chains in planar configurations, at an interplanar spacing of 3.5 Å, and shifted axially by 3.0 Å relative to one another. These calculated results are in good agreement with experimental results obtained on the polymer and on relevant model compounds. No discernible dispersion of the energy bands perpendicular to the planes is observed, indicating that the neighboring chains are electronically noninteractive, as was found earlier for trans-polyacetylene and polyethylene. Similarly, the band gap of 1.69 eV in the axial direction for one of a pair of chains was nearly the same as that, 1.73 eV, calculated previously for an isolated trans-PBT chain. These values are in the range 1.4-1.9 eV reported for trans-polyacetylene, which has been extensively studied because of its promise as a semiconductor.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180211210
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  • 96
    Electronic Resource
    Electronic Resource
    Structure and side-chain interactions in poly(δ-N-carbobenzoxy L-ornithine) (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 413-424 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two crystal modifications are found in α-helical poly(δ-N-carbobenzoxy L-ornithine). In films as cast, the two-dimensional unit cell is pseudohexagonal and contains two chains. This form transforms irreversibly into a pseudotetragonal form at about 140°C. A second-order transition associated with the onset of the side-chain motion is observed at about 30°C for the bulk sample (by dilatometry) and for the crystalline phase (by x-ray diffraction). The dielectric behavior of the side-chain dispersion suggests that the side chains interact with one another. The temperature dependence of the infrared absorbance due to the NH stretching vibration reveals that about half the side chains are associated via hydrogen bonds at room temperature and become dissociated at higher temperature. The enthalpy and the entropy of the hydrogen bond formation is estimated to be ΔH = -5.0 ± 0.5 kcal mol-1 and ΔS = -15 ± 1 e.u. mol-1.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180210308
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  • 97
    Electronic Resource
    Electronic Resource
    Orientation studies on hot-drawn tubular blown films of isotactic polypropene (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 401-411 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Orientation studies of hot-drawn polypropene films were performed using small-angle light scattering and wide-angle and small-angle x-ray scattering over a wide range of deformation. At low deformation, the classical scheme of affine deformation, as several authors have pointed out, seems to be quite realistic. However, for high deformations, i.e., up to 500%, a new conception of the microfibrillar state is proposed. The microfibrils are formed of fully extended crystals which have a high degree of parallel orientation, but deviations of the units from their ideal position occur. “Wrong” chains are embedded in the lattice, long-range order is lost, and paracrystallinity appears. A nematic arrangement develops gradually, and we suppose that the “needlelike entities” have some cylindrical symmetry with a crystalline core. The true amorphous component acts as a connection between these zones.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180210307
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  • 98
    Electronic Resource
    Electronic Resource
    Tests of a “free-volume” model of gas permeation through polymer membranes. I. Pure CO2, CH4, C2H4, and C3H8 in polyethylene (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 467-481 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Permeability coefficients have been measured for CO2, CH4, C2H4, and C3H8 in polyethylene membranes at temperatures of 5, 20, and 35°C and at applied gas pressures of up to 30 atm. The temperature and pressure dependence of the permeability coefficients was represented satisfactorily by an extension of Fujita's free-volume model of diffusion of small molecules in polymers. The results of the present steady-state permeability measurements provide further support for the conclusion reached from previous unsteady-state diffusivity measurements that Fujita's model is applicable to the transport of small molecules, such as CO2, CH4, C2H4, and C3H8, in polyethylene. It was previously thought that this model is applicable only to the transport of larger molecules, such as of organic vapors, in polymers.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180210311
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  • 99
    Electronic Resource
    Electronic Resource
    Diffusivity of gases and main-chain cooperative motions in plasticized poly(vinyl chloride) (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1041-1054 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Permeability and time-lag measurements for H2 and CO in poly(vinyl chloride) (PVC) plasticized with tricresyl phosphate show that the apparent diffusion coefficients at first decrease as the plas-ticizer concentration is increased. The diffusion coefficients then increase as the additive concentration is raised above 15 wt %. These changes in the apparent diffusion coefficients can be related to the behavior of a variety of mechanical properties and are attributed to antiplasticization and plasticization effects of low and high concentrations of tricresyl phosphate, respectively. The antiplasticization-plasticization effects reflect altered molecular motions of the polymer. Carbon-13 NMR rotating-frame relaxation rate measurements show directly that the cooperative main-chain molecular motions of PVC are reduced when the additive acts as an antiplasticizer and are increased when the polymer is plasticized. Both the apparent diffusion coefficient and the rotating-frame relaxation rate have a similar dependence on additive concentration. An application of the molecular theory of diffusion of Pace and Datyner accounts qualitatively for the way in which additives alter the average chain interaction energy, cooperative polymer main-chain motions, and the diffusion coefficients of gaseous penetrants.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180210705
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  • 100
    Electronic Resource
    Electronic Resource
    Solid-state 13C NMR evidence for gas-polymer interactions in the carbon dioxide-poly(vinyl chloride) system (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1055-1062 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The presence of small amounts of CO2 in poly(vinyl chloride) (PVC) results in increased main-chain molecular motions of the polymer as measured by the carbon rotating-frame relaxation rate. This effect increases with increasing gas concentration. Since molecular motions of the polymer and the diffusion coefficient of the gas are related, the latter must be concentration dependent. Main-chain motions of PVC also increase upon exposure to CO2 followed by degassing. This result is interpreted in terms of the effect of the penetrant gas on the interchain packing in amorphous PVC. These results cannot be reconciled with the dual-sorption-mobility model, which claims that gas molecules preferentially occupy preexisting sorption sites in a conditioned polymer with no perturbation of the polymer matrix.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180210706
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