Water sorption into polylactide (PLA) and polylactide‐montmorillonite (PLLA‐MONT) composites containing 5 wt % of montmorillonite (MONT) under different heat treatment conditions was studied using the quartz crystal microbalance/heat conduction calorimetry (QCM/HCC) technique. Results showed that water sorption in neat polymer films and composite films increased with heat treatment temperature up to 120 °C. Differential scanning calorimetry was used to measure the glass‐transition temperature and isothermal crystallization kinetics of all samples. The mobility of the amorphous domain in all samples increased with heat treatment temperature, indicated by the decrease in glass‐transition temperature. PLA composites crystallized at a much faster rate than neat PLA did because MONT acted as a nucleating agent. Under the same heat treatment condition, water sorption in PLLA‐MONT composites was always higher than that in neat PLA due to the presence of the hydrophilic hydroxyl groups on the surface of MONT particles. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Background: Key cellular players regulating human skin pigmentation include melanocytes in the epidermis that synthesize melanin, neighboring keratinocytes that receive and distribute melanin in the upper layers, and fibroblasts in the dermis that affect overlying melanocytes and keratinocytes. In addition, endocrine factors from the blood supply (endothelial cells) and inflammation-related factors play a role. Thus, new strategies for affecting pigmentation need to consider these multiple cell lines to adequately cover various causes and disease processes associated with hyperpigmentation. Methods: Pathophysiologic mechanisms and cellular pathways involved in melanogenesis were thoroughly reviewed with particular emphasis on the cellular interplay involved in the process. A complex system of interlinking and independent pathways was defined and described demonstrating differing pathways for altered pigmentary disorders -melasma associated with endothelial cell interactions; post inflammatory hyperpigmentation associated with keratinocyte inflammatory mediators (PGE2 in particular); and photodamage involving all 4 cell types. In vitro validation studies were then undertaken to define differing cell group gene expression profiles with selected peptides and other active agents. Melanocytic production of pigment was then tested with these agents to identify key potential players capable of limiting pigmentation. Results: Hexapeptide-12 and lactoferrin (melanocytes), Hexapeptide-11 (in keratinocytes), and phosphatidylserine (endothelial cells) were identified as major inhibitors of melanogenesis based on their gene expression profiles. This was confirmed by secondary melanin production tests performed on melanocytic lines. Additional active agents were also identified as inhibitors of melanocytic production of melanin, and together, these constituents formed the basis for a novel formulation for use in pigmentary disorders. Conclusion:A comprehensive scientific narrative of the various facets relating to pigmentation has been presented including differing pathways affecting varied cell lines that effect pigment production. Based on this concept, actives were tested using gene expression studies as well as in vitro melanogenic model testing in different cell lines. Using this novel multi-faceted approach, we have selected and validated a series of active agents to be used in a formulation targeting the complex problem of hyperpigmentation.
The Supreme Court's decision in Roe v. Wade, arguably the most hotly debated in recent decades, has produced an impressive body of historical scholarship. 1 The leading histories have focused on the evolution of the arguments and alliances that shape abortion debate today, rights-based prolife and pro-choice arguments, alliances between women's rights leaders and public health advocates, and the adoption of pro-choice positions by the Democratic Party and pro-life positions by the Republicans. 2 This orientation is unquestionably a sensible one; rights-based arguments, in play ).2. Reagan has studied how the strength of the abortion legalization or reform movements depended on the ability of ordinary women to achieve independence and power over their own lives. See, e.g., Reagan,When Abortion Was a Crime. 18. Condit, by contrast, has studied the development of pro-life and pro-choice rhetoric and the ultimate compromise between pro-life and pro-choice positions, a compromise that framed abortion as "a woman's choice but also as an undesirable moral act." See Condit, Decoding Abortion, 199. Garrow, in turn, has examined the work of the litigators and courts responsible for the Supreme Court's decision in Roe. See Garrow, Liberty and Sexuality, ix-x.
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