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  • Electronic Resource  (13)
  • Polymer and Materials Science  (11)
  • Dopamine  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Amine modulation of electrical coupling in the pyloric network of the lobster stomatogastric ganglion (1993)
    Springer
    Journal of comparative physiology 172 (1993), S. 715-732 
    Details
    ISSN: 1432-1351
    Keywords: Electrotonic coupling ; Stomatogastric ganglion ; Pyloric motor circuit ; Lobster ; Dopamine ; Serotonin ; Octopamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1. The neurons of the pyloric network of the lobster (Panulirus interruptus) stomatogastric ganglion organize their rhythmic motor output using both chemical and electrical synapses. The 6 electrical synapses within this network help set the firing phases of the pyloric neurons during each rhythmic cycle. We examined the modulatory effects of the amines dopamine (DA), serotonin (5HT) and octopamine (Oct) on coupling at all the electrical synapses of the pyloric network. 2. Electrical coupling within the pacemaker group [anterior burster (AB) to pyloric dilator (PD), and PD- 3. Dopamine decreased or increased the coupling strength of all the pyloric electrical synapses: the sign of the effect depended upon which neuron was the target of current injection. For example, DA decreased AB→ PD coupling (i.e., when current was injected into the AB) but increased coupling in the other direction, PD→ AB. Dopamine decreased AB to VD coupling when current was injected into either neuron. Serotonin also had mixed effects; it enhanced PD→AB coupling but decreased AB to VD and PD to VD coupling in both directions. Octopamine's only effect was to reduce PD→ VD coupling. li]4. 5. The characteristic modulation of electrical coupling by each amine may contribute to the unique motor pattern that DA, 5HT and Oct each elicit from the pyloric motor network.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195397
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  • 2
    Electronic Resource
    Electronic Resource
    Independent mediation of unconditioned motor behavior by striatal D1 and D2 receptors in rats depleted of dopamine as neonates (1995)
    Springer
    Psychopharmacology 122 (1995), S. 85-94 
    Details
    ISSN: 1432-2072
    Keywords: D1 receptors ; D2 receptors ; Akinesia ; Catalepsy ; Sensory neglect ; Dopamine ; Development ; Plasticity ; 6-OHDA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of systemic administration of DA receptor antagonists suggest that unconditioned motor behavior in rats depleted of DA as neonates continues to be dependent upon dopaminergic transmission, yet the specific contribution of D1 and D2 receptors to these behaviors has been altered. The purpose of the present study was to determine whether these depletion-induced receptor changes are occurring at the level of striatal DA terminals and their targets. The ability of bilateral intrastriatal injections (0.5 µl) of DA receptor antagonists to induce motoric deficits was determined in adult rats treated with vehicle or 6-OHDA (100 µg, intraventricular) on postnatal day 3. Administration of the D1-like antagonist SCH 23390 (0.5–2.0 µg) or the D2-like antagonist clebopride (1.0–4.0 µg) induced dose-dependent akinesia, catalepsy, and somatosensory neglect in vehicle-treated controls. In contrast, neither antagonist produced deficits in rats depleted of forebrain DA as neonates. However,combined administration of SCH 23390+clebopride induced similar akinesia, catalepsy, and somatosensory neglect in both controls and DA depleted animals. Animals depleted of DA were more sensitive than controls to the low doses of this combined D1+D2 antagonism. These results demonstrate that activation of striatal DA receptors remains necessary for unconditioned motor behavior in rats depleted of DA as neonates. However, the specific contributions of D1- and D2-like receptors to these behaviors differ between intact animals and those depleted of DA as neonates. The ability of endogenous DA acting at either D1 or D2 receptors to support spontaneous motor behavior in rats depleted of DA as neonates may contribute to their relative sparing from parkinsonian deficits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246446
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of nylon-grated polyphenylene etherPresented in part at the 19th Akron Polymer Conferences on “Advances in Heterophase Polymers: Synthesis, Characterization, and Properties” (The Ralph Milkovich Memorial Symposium), Akron, OH, June 19-22, 1988. (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 3371-3382 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyphenylene ether (PPE) resin (a homopolymer made from 2,6-xylenol with an i.v. of 0.46) was reacted with phenyl acrylate, p-substituted phenyl acrylates, and diphenyl fumarate in an extruder or in solution. The number of olefinic molecules that had been grafted onto the PPE backbone was determined by FTIR or NMR methods, and the grafting efficiency and mechanism were examined. The grafted PPE resins were used to promote the anionic polymerization of ε-caprolactam, and the quantity and the composition of the PPE-nylon 6 copolymers isolated were correlated with the number of promoter groups attached to the PPE resin.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1989.080271016
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  • 4
    Electronic Resource
    Electronic Resource
    Radiation resistant amorphous-all aromatic polyarylene ether sulfones: Synthesis, characterization, and mechanical properties (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 287-300 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterization of amorphous, aromatic, polyaryl ethers has been investigated. Detailed synthesis procedures are provided. The main thrust of these activities was to synthesize polymers which could serve as castable amorphous matrix resins for carbonfiber composites and which would be highly resistant to radiation degradation. It was important that these polymers not contain any aliphatic groups in order to contrast their behavior with the commercially available Bisphenol-A polysulfones. The approach taken was to synthesize a series of statistical or random copolymers derived from hydroquinone and biphenol together with 4,4′-dichlorodiphenyl sulfone. In order to produce copolymers of high molecular weight, modified techniques were developed which utilized potassium carbonate as a weak base and N-methyl-2-pyrrolidone as the aprotic dipolar solvent. Detailed procedures are provided in this paper for the synthesis of high molecular weight copolymers of this type. In addition, stress-strain, dynamic mechanical properties and preliminary electron beam (e-beam) degradation studies are reported significantly. Improved mechanical property retention after e-beam exposure was observed with the all aromatic polyether sulfones.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240208
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  • 5
    Electronic Resource
    Electronic Resource
    Water penetration in glassy polymers: Experiment and theory (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 48 (1993), S. 319-334 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: We describe the design and implementation of a method based on infrared monitoring of the OD stretch mode which permits measurement of the diffusion profiles of water permeating glassy polymers for the first time. Results for several glassy polymers are compared with a theory of trapping diffusion which leads to a nonlinear diffusion problem in which the trapped water penetrates the polymer as a sharp front if there is a large amount of trapping. In the case of two of the polymers studied, the trapping model describes the data, very well (much better than a simple diffusion model) and permits determination of parameters related to the free volume and the residence time of the water on traps in the model. © 1993 John Wiley & Sons, Inc.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070480216
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  • 6
    Electronic Resource
    Electronic Resource
    The preparation of crystalline polypropylene sodium sulfonates and their interaction with an included sodium hydroxide phase (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 17 (1973), S. 553-564 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Sodium sulfonated polypropylenes have been prepared by the slurry chlorosulfonation of polypropylene or propylene - ethylene copolymer followed by hot aqueous sodium hydroxide treatment. Low levels of excess sodium hydroxide were added to the materials to stabilize them against thermal decomposition. It was found that there was a strong interaction between the sodium hydroxide phase and the polymer sodium sulfonate groups which persisted above the nominal melting point of crystalline polypropylene. Evidence for the interaction includes an increased melt viscosity and a greatly increased nucleation rate for the composites as compared to the polypropylene sodium sulfonates not containing the sodium hydroxide phase. The composites have an improved balance of mechanical properties as compared to the materials from which they are prepared.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1973.070170218
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  • 7
    Electronic Resource
    Electronic Resource
    Graft copolymerization of acrylic acid to nylon 6 by mutual irradiation. II. The influence of cupric ions (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 921-928 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In the γ-irradiation in vacuo of nylon 6 film in the presence of aqueous acrylic acid and different concentrations of cupric chloride, the following relationships have been obtained: RH ∝ [CuCl2]-1.0 and RG ∝ [CuCl2]-0.3 Here [CuCl2] is the concentration of cupric chloride in the bulk solution, and RH and RG denote the initial rates of homopolymerization and grafting, respectively. The values of -1.0 and -0.3 for the exponents indicate that the cupric ion is a less effective chain terminator in the film on account of its lower concentration there. Analyses of films grafted in different media demonstrate the copper content of a film to be independent of both the concentration of monomer in the solution and the degree of swelling. The copper content is primarily a function of the total poly(acrylic acid) present, i.e., (grafted species plus occluded homopolymer). Thus, at high doses, where the total poly(acrylic acid) associated with a film is significant, the grafting curves exhibit a falling off, and complex formation between cupric ion and a growing chain is considered a likely contributory factor.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1972.070160411
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  • 8
    Electronic Resource
    Electronic Resource
    Intrinsic viscosity-molecular weight relationship for low molecular weight nylon 6 (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 12 (1968), S. 2105-2109 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Samples of nylon 6 have been prepared by the hexamethylene diamine-initiated polymerization of ∊-caprolactam at 220°C. Fractionation of these with m-cresol-diethyl ether at 26°C yielded 15 amino-terminated fractions of M̄n of 337-10,940 determined conductometrically. Below M̄n = 4,306 the Mark-Houwink parameters in m-cresol at 30°C are K = 3.0 × 10-3 dl/g and v = 0.53 ± 0.02. Thereafter v exhibits a pronounced increase. The value of K is similar to the values of Kθ derived from Stockmayer-Fixman plots of published data in good solvents. The findings thus corroborate a current hypothesis that fractionated, low molecular weight polymers in good solvents tend to behave viscometrically, as if they were under θ conditions (i.e., K = Kθ and v = 0.50).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1968.070120913
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of sulfonated poly(acrylene ether sulfones)This paper is dedicated to Professor V. T. Stannett on the occasion of his 65th birthday. (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 721-737 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ionic groups incorporated into a polymer have a decided effect on its physical properties. A number of ionomers and polyelectrolytes have been widely applied. In particular, sulfonated bisphenol-A polysulfone (SPSF) has been used as a composite or single-component membrane for the desalination of water. In this article, the synthesis and physical characteristics of sulfonated polysulfone are addressed. A detailed synthesis route is provided and methods that yield determinable levels of sulfonation are described. These ion-containing polymers retain an excessive amount of residual salts, which, of course, are impurities to the system. Therefore, before any analyses were made the polymers were subjected to a thorough soxhlet extraction process with boiling water, which appeared to be quite effective. The degree of sulfonation was assessed by several methods such as 1H NMR and FT-IR. A new 1H NMR method was derived because the method cited in the literature proved to be too inconsistent for our work. The new 1H NMR method used a quaternary ammonium counterion [N(CH3)4]. These methyl protons are easily measured and may be ratioed against the isopropylidene protons in the polymer backbone that act as an internal standard. Characterization of the physical properties of SPSF consisted of water uptake, differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and solubility studies. Its physical appearance and mechanical behavior were improved by the solution procedure. Also addressed were the effects of different counterions (Na+ & Mg++) with SPSFs of low levels of sulfonation. The variation in physical properties between the divalent and monovalent counterions is dramatic, especially when observed by TMA in the rubber plateau above the apparent glass temperature.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.170220320
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  • 10
    Electronic Resource
    Electronic Resource
    Vapor phase polymerization of 1,3-butadiene with sodiumThis investigation was carried out under the sponsorship of the Office of Rubber Reserve, Reconstruction Finance Corporation, in connection with the Government Synthetic Rubber program. (1948)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 3 (1948), S. 283-296 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Apparatus and technique have been described for the polymerization of 1,3-butadiene in the vapor phase with sodium as catalyst. Research grade butadiene or that obtained from alcohol is necessary for production of high molecular weight polymers by this method. Unmodified polymerizations with increased sodium surface go faster and produce polymers of lower gel content and inherent viscosity. Increase in polymerization temperature reduces the rate, gel content, and inherent viscosity. The chemical structure of the modifier seems to be the predominant factor in its efficiency within a concentration range of 0.1 to 1.0 %. Ethyl chloride is the most powerful modifier of those examined, followed in order by dimethylamine, acetaldehyde, and acetoue. Gelfree polymers with average inherent viscosities of the whole sol between 0.4 and 4.6 were vulcanized and evaluated. The weight distribution was found to be rather narrow for the low viscosity polymers but to become broader as the average inherent viscosity of the polymer increased. Optimum processing and tensile properties were obtained on the polymers of medium viscosity. The dynamic properties of the vulcanizates improve with increase in average inherent viscosity of the raw polymer; the ethyl chloride modified polymer is exceptionally good. The physical properties of the vulcanizate of a blend of equal parts of five polymers of inherent viscosity 1.0 to 4.6 were near those of the lowest molecular weight polymer.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1948.120030213
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