This paper details the characteristics of pure cellulose and wood fibers when associated with thermoplastic matrices for composite applications. Chemical modification of the cellulose is performed to allow a good compatibilization, and the most efficient compatibilizing agents must possess: (i) a function highly reactive with the OH groups of the cellulose and (ii) a non‐polar chain with preferably a polymeric structure. Polypropylenes grafted with maleic anhydride are thus efficient agents. Smaller compatibilizing agents, especially if reacted with cellulose in swelling media, react with the bulk of the fiber and lead to dimensional stability. All treatments, even when performed with low degrees of grafting or small alkyl chains, significantly modify the hydrophilicity of the cellulose surface and play a role in a better wettability of the fiber by the matrix leading to improved adherence. The global mechanical properties are then improved, but the effect is preferably studied at the scale of a single filament composite. The morphology of the matrix in the vicinity of the non‐treated fiber shows that, in some cases, the fiber acts as a nucleating agent involving the formation of a transcrystalline phase. Aging in moisture is generally detrimental to the mechanical properties. This phenomenon is limited by the chemical treatment performed on the fibers.
Our findings do not indicate that there are associations between maternal or newborn polymorphisms associated with thrombophilia and an increased risk of intrauterine growth restriction.
Summary. Background: The role of anticoagulants for the prevention of placental-mediated pregnancy complications is uncertain. Objectives: Our aim was to investigate the effectiveness of dalteparin, a low-molecular-weight heparin, in preventing the recurrence of these complications in women without thrombophilia. Patients/methods: Between August 1 2000 and June 20 2007, 116 pregnant women with: (i) £ 16 weeksÕ gestation, (ii) no detectable thrombophilia, (iii) previous severe pre-eclampsia, newborn weight £ 5th percentile, unexplained intrauterine death or abruptio placentae were randomized to either a prophylactic daily dose of dalteparin (n = 58) or no dalteparin (n = 58). The primary outcome was a composite of one or more of: severe pre-eclampsia, newborn weight £ 5th percentile or major abruptio placentae. Secondary outcomes included non-severe pre-eclampsia, newborn weight at the 6-10th percentile and gestational age at delivery. Analyses were by intention to treat. P < 0.05 was considered to be significant. This study is registered as an International Standard Randomized Controlled Trial, number ISRCTN78732833. Results: Among the 110 women included in the final analysis, dalteparin was associated with a lower rate of the primary outcome [5.5% (n = 3/55) vs. 23.6% (n = 13/55), adjusted odds ratio (OR) 0.15, 95% confidence interval (CI) 0.03-0.70]. Secondary outcomes were not statistically different between the groups. Bleeding problems or thrombocytopenia did not occur. Conclusion: In this pilot study, dalteparin is effective in decreasing the recurrence of placental-mediated complications in women without thrombophilia. Our results require confirmation in further randomized trials.
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