Influence of shape on the reactivity and properties of dendritic, hyperbranched and linear aromatic polyesters

Previously described dendritic and hyperbranched polyesters and a new linear polyester obtained by polymerization of 3-hydroxy-5-(t-butyldimethylsilyloxy)benzoic acid, each based on the 3,5-dihydroxybenzoic acid building block, were used in the study of differences in chemical and physical properties between the three different polymer architectures. Comparison of the physical properties between the dendritic, hyperbranched and linear structures showed that thermal properties, such as glass transition temperature and thermogravimetric analysis, were independent of macromolecular architecture. However, the dendritic and hyperbranched materials demonstrated comparative solubilities which were much greater than that found for the linear polymer. Other differences were observed in chemical reactivities

Physical Properties of Dendritic Macromolecules: A Study of Glass Transition Temperature

The variation of glass transition temperature with molecular weight and chain-end composition for dendritic polyethers and polyesters was studied. A new and modified version of the chain-end free volume theory was derived to account for the large number of chain ends in these unusual structures. For both homopolymers and a variety of novel block copolymers, the experimental variation in T with molecular weight was found to correlate well with theoretical predictions, thus demonstrating the wide applicability of the chain-end free volume theory. The glass transition was found to be greatly affected by the nature of the chain ends and internal monomer units

Dendrimer and polystyrene surfactant structure at the air-water interface

The Π-A isotherms at the air-water interface and 25°C for monomolecular films of the recently synthesized dendrimer surfactants are reported and compared with those of polystyrene terminated with a single hydroxyl group. There is a strong dependence of the isotherms on molecular weight (MW) for both systems, the lower MWs typified by an increase in the surface pressure through a liquid expanded phase, followed by a peaked collapse transition, indicating a nucleation and growth process, to a liquid condensed, phase. The higher molecular weight dendrimer and polystyrene isotherms are also similar, with a steep increase in the surface pressure being due to a direct transition to a solid phase

Supplementary Material for: Intracranial Stenosis: Impact of Randomized Trials on Treatment Preferences of US Neurologists and Neurointerventionists

<b><i>Background and Purpose:</i></b> Medical and endovascular treatment options for stroke prevention in patients with symptomatic intracranial stenosis have evolved over the past several decades, but the impact of 2 major multicenter randomized stroke prevention trials on physician practices has not been studied. We sought to determine changes in US physician treatment choices for patients with intracranial atherosclerotic stenosis (ICAS) following 2 NIH-funded clinical trials that studied medical therapies (antithrombotic agents and risk factor control) and percutaneous transluminal angioplasty and stenting (PTAS). <b><i>Methods:</i></b> Anonymous surveys on treatment practices in patients with ICAS were sent to physicians at 3 time points: before publication of the NIH-funded Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) trial (pre-WASID survey, 2004), 1 year after WASID publication (post-WASID survey, 2006) and 1 year after the publication of the NIH-funded Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) trial (post-SAMMPRIS survey, 2012). Neurologists were invited to participate in the pre-WASID survey (n = 525). Neurologists and neurointerventionists were invited to participate in the post-WASID (n = 598) and post-SAMMPRIS (n = 2,080) surveys. The 3 surveys were conducted using web-based survey tools delivered by E-mail, and a fax-based response form delivered by E-mail and conventional mail. Data were analyzed using the χ² test. <b><i>Results:</i></b> Before WASID, there was equipoise between warfarin and aspirin for stroke prevention in patients with ICAS. The number of respondents who recommended antiplatelet treatment for ICAS increased across all 3 surveys for both anterior circulation (pre-WASID = 44%, post-WASID = 85%, post-SAMMPRIS = 94%) and posterior circulation (pre-WASID = 36%, post-WASID = 74%, post-SAMMPRIS = 83%). The antiplatelet agent most commonly recommended after WASID was aspirin, but after SAMMPRIS it was the combination of aspirin and clopidogrel. The percentage of neurologists who recommended PTAS in >25% of ICAS patients increased slightly from pre-WASID (8%) to post-WASID surveys (12%), but then decreased again after SAMMPRIS (6%). The percentage of neurointerventionists who recommended PTAS in >25% of ICAS patients decreased from post-WASID (49%) to post-SAMMPRIS surveys (17%). <b><i>Conclusions:</i></b> The surveyed US physicians' recommended treatments for ICAS differed over the 3 survey periods, reflecting the results of the 2 NIH-funded clinical trials of ICAS and suggesting that these clinical trials changed practice in the USA

Sleeping sites of woolly mouse opossum Micoureus demerarae (Thomas) (Didelphimorphia, Didelphidae) in the Atlantic Forest of south-eastern Brazil

Micoureus demerarae (Thomas, 1905) is a medium-sized marsupial, around 130 g, with a nocturnal habit and insectivorous-omnivorous diet. From August 2001 to July 2002, seven individuals, three males and four females, were monitored with radio-telemetry in Reserva Biológica União, state of Rio de Janeiro, Brazil, aiming to investigate and describe the sleeping sites used by this marsupial. Fifty eight sleeping sites were located, most of which (70,7%) in palm trees Astrocaryum aculeatissimum (Schott) Burret, and the remaining in other tree species (29,3%), a significant difference (chi2 test; p < 0.005). The preference for this palm tree was not different between sexes (chi2 test; p = 0.920). It was possible to locate the exact place where the animal was hiding in 31 sleeping sites (53.4% of total) in palm trees the animals were always in the junction point of petioles and tree trunks, at an average height of 4.66 ± 1.36 m, while in the remaining tree species, seven individuals were in liana tangles and two in tree holes, at an average height of 10.67 ± 2.75 m. This height difference was significant (Mann Whitney test; p < 0.001). Results indicate that palm trees are important resources for M. demerarae. The observed preference for A. aculeatissimum is probably due to higher protection against predators made by the numerous spines of this palm tree species.<br>Micoureus demerarae (Thomas, 1905) é um marsupial de tamanho médio, cerca de 130 g, de hábito noturno e arborícola e dieta insetívora-onívora. No período de agosto de 2001 a julho de 2002, sete indivíduos, três machos e quatro fêmeas, foram acompanhados, através de rádio-telemetria, na Reserva Biológica União, Rio de Janeiro, com o objetivo de investigar e descrever os abrigos utilizados por essa espécie de marsupial. Foram localizados 58 abrigos, a maioria dos quais (70,7%) em palmeiras Iri Astrocaryum aculeatissimum (Schott) Burret e o restante em outras espécies de árvores (29,3%), uma diferença significativa (teste chi2; p < 0,005). Esta preferência por palmeiras não foi significativamente diferente entre os sexos (teste chi2; p = 0,920). Em 31 abrigos (53,4% do total) o local exato onde o animal se encontrava pode ser localizado: nas palmeiras os animais sempre estavam alojados no local de inserção dos pecíolos junto ao tronco e a uma altura média de 4,66 ± 1,36 m, enquanto nas demais espécies de árvores, sete animais estavam em emaranhados de cipós e dois em ocos, a uma altura média de 10,67 ± 2,75 m. Esta diferença de altura entre abrigos em iris e não iris foi significativa (teste Mann Whitney; p < 0,001). Os resultados indicam que as palmeiras iris são um importante recurso para M. demerarae. A preferência por A. aculeatissimum se deve provavelmente à maior proteção contra predadores exercida pelos numerosos espinhos presentes nesta espécie