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  • 1
    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
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inorganic and organometallic polymers and materials 2 (1992), S. 29-45 
    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
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inorganic and organometallic polymers and materials 1 (1991), S. 545-565 
    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
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