Acyclic diene metathesis (ADMET) polymerization has been used to synthesize latent reactive processable elastomers constructed of carbosilane and polyether segments. Two types of latent modes have been introduced: “chain‐internal” and “chain‐end” sites through the use of labile silicon methoxy functionalities. These latent reactive groups are inert when exposed to metathesis conditions allowing formation of the linear copolymer; subsequently exposure to moisture triggers hydrolysis of the methoxy groups and formation of a chemically crosslinked thermoset. The thermoset's mechanical response can be potentially varied from plastic to elastic behavior, depending on the ratio of carbosilane and oligooxyethylene monomers employed. Different lengths of glycols and numbers of methylene groups between them in the polymer backbone have been investigated to explore structure/property relationship. Polymers composed of oligooxyethylenes with eight methylene groups in between them exhibited fully amorphous character, while the ones with up to 20 methylene groups between glycol units showed their semicrystalline nature. The concentration of “chain‐internal” and “chain‐end” crosslink sites enhances strength; modification to the run length and structure of the soft phase enhances elasticity. Resultant materials have been subjected to mechanical tests using Instron; generated stress/strain curves have shown plastic and elastic behavior. Depending on the composition obtained samples have shown moduli from 0.3 to 115 MPa, tensile strengths from 0.6 to 10 MPa and elongations from 20 to 700%. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3992–4011, 2008
We have read with interest the article written by Schnatz et al 1 called BOsteoporosis screening and treatment guidelines: are they being followed?[ 1 The conclusion was that the guidelines for dual-energy x-ray absorptiometry screening put forth by The North American Menopause Society are not being followed. In 2005, we looked at the adherence to the 2002 United States Preventive Service Task Force guidelines for osteoporosis screening, BScreening for osteoporosis in postmenopausal women: adherence to the 2002 USPSTF Guidelines.[ 2 Our analysis broke down patients by age groups (G50, 50-59, 60-65, and 965 y) and body mass (more or less than 70 kg). We found that there was an overuse of dual-energy x-ray absorptiometry scanning in women younger than 60 and an underuse in high-risk women (G70 kg) or women older than 65 years. This recent study has reinforced our previous conclusions, with the added analysis of undertreatment of those with indications for therapy and the overuse of therapy for those in which none is indicated. The study by Prairie et al 1 (BA higher sense of purpose in life is associated with sexual enjoyment in midlife women[) is to be commended for its multidisciplinary approach, which yielded multidisciplinary answers. Purpose is noted to be a cognitive variable. In the opinion of the authors, how adequate for understanding the diverse results of this study might a neurological interpretation be? An attempt to summarize it in such terms is given below.MacLean's 2 classic model offers a convenient framework, in which each higher brain level tends to control lower levels, whereas lower levels report continuously to higher. The three major brain levels involved in this model are the cerebrocortical, which involves cognition and is distinctly human; the limbic system, which is emotional, our mammalian heritage; and the thalamic-hypothalamic system, our sensory reptilian inheritance.A sense of purpose is a distinctly human cortical event involving typical frontal lobe action. So massive are the cerebral hemispheres, however, that, as revealed in this study, senses of purpose and of sexual satisfaction can Bcosegregate[ or act as separate variables in different motivational contexts. When integrated with emotional feeling and sexual need, however, the sense of purpose is found to add to overall sexual enjoyment.Sexual enjoyment involves emotional aspects, input from the limbic system, and sensory aspects or impulses from the thalamus and hypothalamus. Although the findings relating to hormone therapy in this study did not quite reach statistical significance, there are strong suggestions that in their reporting of function to higher levels, the hormonal status of peripheral tissues influences sexual pleasure. Vaginal dryness significantly detracts, whereas hormone therapy appears to enhance sexual performance.Although a sense of purpose adds to sexual enjoyment, this higher dimension, in itself, does not lead to more frequent sexual experience. In the results of this study, the rate of sexual activity...
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