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  • mesophases  (2)
  • Addiction  (1)
  • Cigarette  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Some recent developments in polysilane chemistry (1992)
    Springer
    Journal of inorganic and organometallic polymers and materials 2 (1992), S. 29-45 
    Details
    ISSN: 1572-8870
    Keywords: Polysilenes ; polysilanes ; liquid crystals ; mesophases ; birefringence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract (I) Ordered and disordered polysilane copolymers: Condensation of ClSiMe2Si(n-Hex)2SiMe2Cl with Na/K in toluene at 90°C produced a polymer with a strongly bimodal molecular weight distribution. The high-M w and low-M w portions were separated by fractional precipitation with 2-propanol, and the properties of the two fractions were investigated.29Si-NMR spectra show that the low-M w fraction is fully ordered but the high-M w fraction is randomized. (II) Liquid crystalline polysilanes: Condensation ofn-Bu(n-Hex)SiCl2 with Na in toluene led to a homopolymer which is a rubbery solid at 25°C. The polymer undergoes a second-order transition at −45°C and a first-order (melt) transition at −20°C. X-ray diffraction shows that the polymer has the same structure, a columnar hexagonal lattice, in all three phases; from −20 to 〉200°C, it exists in a columnar liquid crystalline mesophase. Similar hexagonal mesophases were observed at 25°C for the family of copolymers, (n-Hex2Si) n (Alk2Si) m , Alk =n-Pentyl,n-Bu,n-Pr, Et, Me.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696534
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  • 2
    Electronic Resource
    Electronic Resource
    Ethynylene-disilanylene copolymers (1991)
    Springer
    Journal of inorganic and organometallic polymers and materials 1 (1991), S. 545-565 
    Details
    ISSN: 1572-8870
    Keywords: Polysilanes ; sigma-pi conjugation ; mesophases ; polymer crystals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Polymers of structure (SiR2SiR2-C ≡ C-SiR2′SiR2′-C ≡ C) n , in which ethynylene units alternate with disilylene units, have been prepared by two routes: (a) condensation of dichlorodisilanes with dilithium derivatives of 1,2-diethynyldisilanes and (b) ring-opening polymerization of strained cyclic disilanylene-acetylnes, (SiR2SiR2C ≡ C)2. The polymers display UV absorption near 240 nm indicative of σ − π conjugation between the Si2 and the C ≡ C moieties. Polymers with R=R′=n-Bu or R=n-Bu, R′=Ph, undergo solid-state transitions to form liquid crystalline mesophases resembling those observed for many poly(silylenes). Single crystals were obtained for the polymer with R=R′=CH3, by precipitation from dilute cyclohexane solution. The solid-state properties and structures of this family of polymers are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00683516
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  • 3
    Electronic Resource
    Electronic Resource
    Pre-abstinence smoke intake and smoking motivation as predictors of severity of cigarette withdrawal symptoms (1985)
    Springer
    Psychopharmacology 87 (1985), S. 334-336 
    Details
    ISSN: 1432-2072
    Keywords: Withdrawal ; Cigarette ; Nicotine ; Dependence ; Motivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Twenty-nine cigarette smokers completed a smoking motivation questionnaire and had expired-air carbon monoxide (CO) and plasma nicotine concentrations measured prior to abstaining from smoking for 24 h. Before and after the abstinence period, the subjects rated mood and physical symptoms known to be affected by cigarette abstinence (e.g. irritability, restlessness). Scores on the “dependent smoking” subscale of the smoking motivation questionnaire correlated significantly with overall withdrawal severity, craving, and increased irritability. “Indulgent smoking” scores correlated positively with increased hunger. Pre-abstinence plasma nicotine concentration significantly pedicted craving, hunger, restlessness, inability to concentrate and overall withdrawal severity, while expired-air CO predicted craving and restlessness only. Usual daily cigarette consumption did not significantly predict any withdrawal effects. The data indicate that pre-abstinence measures of smoking motivation and smoke intake may provide a guide to withdrawal severity on smoking cessation and that smokers with a high pre-abstinence nicotine intake experience the greatest discomfort.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432717
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  • 4
    Electronic Resource
    Electronic Resource
    Nicotine addiction: a re-analysis of the arguments (1992)
    Springer
    Psychopharmacology 108 (1992), S. 408-410 
    Details
    ISSN: 1432-2072
    Keywords: Smoking ; Nicotine ; Dependence ; Addiction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This paper evaluates the arguments put forward by Robinson and Pritchard (R&P, this volume) that the conclusions of the US Surgeon General (USDHHS 1988) that nicotine is addictive were ill founded. R&P state that nicotine does not cause intoxication, that many smokers do not exhibit compulsive use, that nicotine is not a euphoriant, that nicotine is a weak reinforcer in other species, that non-pharmacological aspects of smoking are important and that negative affect control accounts for more of the variance in questionnaire measures of smoking motives than does habit. This paper points out that intoxication and a euphoriant effect are not normally considered to be central to dependence potential, that no addictive drug results in compulsive use in all users in all situations, that animals do reliably self-administer nicotine, that evidence concerning the apparent importance of non-pharmacological components of smoking do not diminish the importance of pharmacological aspects and that “variance accounted for” of self-report measures of smoking motivation do not bear on the issue of the importance of those motives. The paper concludes with a summary of the essence of the argument that cigarettes are addictive and that nicotine is the primary focus of that addiction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247413
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    Paper (German National Licenses)
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