No abstract

ABSTRACT:Tensile drawing and short-term creep of ethylene/␣-olefin copolymers having bimodal (BM) molar weight distribution are studied in comparison with unimodal (UM) copolymers of similar crystallinity. The natural draw ratio and viscoelastic recovery upon unloading strongly suggest that BM copolymers have more tie chains and chain entanglements than corresponding UM copolymers. The incorporation of co-units in the longest chains of BM copolymers is ascribed a major role on these topological changes. Creep of isotropic materials shows lower compliance for BM copolymers in parallel with higher-durability grades. This is attributed to a better "macromolecular network efficiency." The creep behavior of strain-hardened samples, which is assumed to simulate the mechanical behavior of craze fibrils at the tip of a propagating crack, reveals similar trends. The better fibril strength in BM copolymers is again ascribed to a better network efficiency. Necked samples display an odd behavior of higher compliance at low stress and lower compliance at high stress for BM copolymers compared with the behavior of UM counterparts. This is associated with the exhaustion of viscoelastic capabilities with increasing draw ratio and stress. The phenomenon is discussed in relation to cavitation. A short-term creep test is proposed for comparative prediction of long-term behavior.

In situ small‐angle X‐ray scattering of high density polyethylene under uni‐axial tensile test was used for investigating the deformation at the scale of the periodic crystalline–amorphous nano‐structure. The more or less uniform elastic straining of the rubbery amorphous layers is discussed in terms of mechanically active intercrystalline tie chains. Correlation is made with the long‐term use properties. It is concluded that this approach is a powerful means to assess the mechanical efficiency of tie molecules. Copyright © 2004 Society of Chemical Industry

Background:Physician counseling on the risks of tobacco smoking and the benefits of cessation has been shown to be an effective method of increasing the rate of smoking cessation. Using the “Help Your Patients Quit Smoking: A Coaching Guide” also referred to as the “7A's of Smoking Cessation” guideline from the New York City Department of Health and Mental Hygiene is thought to be effective to convey the importance of smoking cessation.Aim:To study the efficacy of the “7A's of Smoking Cessation” guideline counseling conducted by osteopathic medical students.Materials and Methods:Osteopathic medical students were trained to counsel smokers for 3–10 min based on New York City Department of Health's “7A's of Smoking Cessation” guidelines by a licensed physician. Students then counseled health fair participants who were cigarette smokers for 3–10 min. Postcounseling, participants were administered an 4 question survey to evaluate the effect counseling had on their desire to quit smoking. Survey data were collected and analyzed. Institutional Review Board approval was obtained for this study.Results:A total of 13 anonymous health fair participants who were also smokers were administered both counseling sessions and surveys. 11/13 (84.6%) participants stated that the session motivated them to quit smoking. 9/13 (69.2%) participants responded that they were now motivated to discuss smoking cessation with their doctor after being counseled. Of these participants 12/13 (92.3%) had previously attempted to quit smoking without success.Conclusion:Participants reported an increased willingness to stop smoking after being counseled by osteopathic medical students. Participants also reported an increased motivation to discuss smoking cessation with their physician. These findings indicate that smoking cessation counseling administered by osteopathic medical students effectively in encouraging smokers to consider reduction or cessation of tobacco use.