bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-term outcome of patients with hereditary hemorrhagic telangiectasia and severe hepatic involvement after orthotopic liver transplantation: A single-center study
Authors: Dupuis-Girod Sophie , Chesnais Anne-Laure , Ginon Isabelle , Dumortier Jérôme , Saurin Jean-Christophe , Finet Gérard , Decullier Evelyne , Marion Denis , Plauchu Henri , Boillot Olivier
Published: January 2010

Hepatic involvement occurs in up to 74% of patients with hereditary hemorrhagic telangiectasia (HHT) and is characterized by a spectrum of arteriovenous malformations. Three different types of intrahepatic shunting may be present: hepatic artery to hepatic veins, hepatic artery to portal vein, and portal vein to hepatic vein. Hepatic involvement in HHT may lead to biliary ischemia, portal hypertension, or high-output cardiac failure (HOCF). Orthotopic liver transplantation (OLT) has been proposed as the only definitive curative treatment. The aim of this study was to evaluate the long-term outcome of patients with hepatic involvement due to HHT after OLT with respect to mortality, cardiac and hepatic status, epistaxis, and quality of life. Patients with HHT and severe hepatic vascular malformations who underwent OLT in the Lyon Liver Transplant Unit (LLTU) from 1993 to 2007 were followed at the LLTU and the French Reference Center for HHT. Quality of life was evaluated with the Short Form 36 questionnaire. There were 13 patients who fulfilled the entry criteria of the study (12 women and 1 man). The mean age at the time of OLT was 51.8 years (range = 33-65 years). Indications for OLT were cardiac failure (n = 9), biliary necrosis (n = 2), both cardiac failure and biliary necrosis (n = 1), and hemobilia (n = 1). The mean duration of follow-up was 109 months (range = 1-200 months). Twelve patients (92.3%) are still alive. For the 9 patients with HOCF, the mean cardiac index decreased from 5.4 L/minute/m2 before OLT to 3.0 L/minute/m2 after OLT. No severe hepatic complications were observed after OLT. Nine of the surviving patients (75%) experienced dramatic improvements in epistaxis and quality of life, including an ability to undertake more physical activity. In conclusion, OLT is an important therapeutic option for patients with HHT who have severe hepatic involvement. In the reported cohort, the mortality after OLT for this indication was low. Liver Transpl 16:340–347, 2010. © 2010 AASLD.
Microbial epidemiology and outcome of bloodstream infections in liver transplant recipients: An analysis of 259 episodes
Authors: Bert Frédéric , Larroque Beatrice , Paugam-Burtz Catherine , Janny Sylvie , Durand Francois , Dondero Fédérica , Valla Dominique-Charles , Belghiti Jacques , Moreau Richard , Nicolas-Chanoine Marie-Hélène
Published: January 2010

Bloodstream infections (BSIs) are a major cause of mortality in liver transplant recipients. The incidence, microbiology, and outcome of BSIs in the first year after liver transplantation were analyzed in 704 patients who underwent transplantation at a single center between 1997 and 2007. BSIs occurred in 205 (29.1%) of the 704 patients. Overall, 259 episodes were documented, and they resulted in an incidence rate of 36.8%. Of these episodes, 39.4%, 27.8%, 17%, and 15.8% occurred in the very early period (≤10 days after liver transplantation), the early period (days 11-30), the intermediate period (days 31-90), and the late period (days 91-365), respectively. The most frequent pathogens were Enterobacteriaceae members (41%), Staphylococcus aureus (19.8%), enterococci (13.1%), Pseudomonas aeruginosa (8.8%), and yeasts (7.1%). The median time of onset ranged from 7 days for methicillin-resistant S. aureus to 25 days for Enterobacteriaceae. Mortality at 15 days after BSIs was 16.2%. Kaplan-Meier survival curves showed that patients with BSIs had a significantly higher 1-year mortality rate than those without BSIs (28.3% versus 16.6%, P < 0.001 with the log-rank test). When the time of BSI onset was considered, 1-year mortality was significantly associated with very early and early episodes (P < 0.001) but not with intermediate and late episodes (P = 0.47). In conclusion, BSIs are frequent and early complications after liver transplantation and are mostly caused by gram-negative bacilli. A BSI in the first posttransplant month is a significant predictor of 1-year survival. Liver Transpl 16:393–401, 2010. © 2010 AASLD.
Tumor recurrence following liver transplantation for hepatocellular carcinoma: Role of tumor proliferation status
Authors: Marshall Aileen E. , Rushbrook Simon M. , Vowler Sarah L. , Palmer Christopher R. , Davies Justin R. , Gibbs Paul , Davies Susan E. , Coleman Nicholas , Alexander Graeme J. M.
Published: January 2010

The selection of patients with hepatocellular carcinoma for liver transplantation is currently based on the size and number of tumors to minimize the risk of recurrence. These criteria measure tumor bulk but may not reflect tumor behavior accurately. A biological marker of tumor behavior could aid with patient selection further. The aims of this study were to determine factors associated with a higher risk of tumor recurrence and to assess the role of tumor proliferation status with respect to recurrence following transplantation. Pathological data on 67 patients who underwent transplantation for hepatocellular carcinoma were reviewed, and tumor proliferation was assessed by minichromosome maintenance protein-2 (MCM-2) and cyclin A expression. A Cox regression analysis of factors related to tumor recurrence and overall survival was carried out. Recurrence-free survival was assessed according to compatibility with selection criteria, vascular invasion, and proliferation status. Tumor size, vascular invasion, and highest MCM-2 expression were associated with tumor recurrence by multivariate analysis (P < 0.02). Recurrence-free survival was significantly better for those patients without vascular invasion, those who were within the Milan, University of California San Francisco (UCSF), or Up-to-Seven selection criteria, and those with lower expression of MCM-2. In conclusion, tumors meeting the Milan, UCSF, or Up-to-Seven selection criteria had a lower rate of recurrence following liver transplantation. Vascular invasion and tumor proliferation status were associated with the risk of recurrence independently of tumor size. Biopsy of larger tumors to assess proliferative activity could identify those at lower risk of recurrence who could also benefit from liver transplantation. Liver Transpl 16:279–288, 2010. © 2010 AASLD.
Morphological features of advanced hepatocellular carcinoma as a predictor of downstaging and liver transplantation: An intention-to-treat analysis
Authors: Barakat Omar , Wood Patrick R. , Ozaki Claire F. , Ankoma-Sey Victor , Galati Joseph , Skolkin Mark , Toombs Barry , Round Mary , Moore Warren , Mieles Luis
Published: January 2010

In selected patients, locoregional therapy (LRT) has been successful in downstaging advanced hepatocellular carcinoma (HCC) so that the conventional criteria for liver transplantation (LT) can be met. However, the factors that predict successful treatment are largely unidentified. To determine these factors, we analyzed our experience with multimodal LRT in downstaging advanced HCC before LT in a retrospective cohort study. Thirty-two patients with advanced HCC exceeding conventional and expanded criteria for LT underwent therapy, but only those patients whose tumors were successfully downstaged were considered for LT. Eighteen patients (56%) had their tumors successfully downstaged; 14 patients (44%) did not. No intergroup differences existed with respect to patient characteristics or the types and number of treatments. However, mean alpha-fetoprotein levels were significantly higher in the non-downstaged group than in the downstaged group (P < 0.048), and significantly more patients in the non-downstaged group had infiltrative tumors (P = 0.0001). The median survival time was 42 and 7 months for the downstaged and non-downstaged groups, respectively (P = 0.0006). Fourteen patients (43.3%) underwent LT. After a median follow-up period of 35 months (range, 1.5–50 months) after LT, 2 patients (14.2%) developed tumor recurrence. The Kaplan-Meier survival rates after LT were 92% at 1 year and 75% at 2 years. The noninfiltrative expanding tumor type was the sole predictor of successful downstaging and improved outcome on univariate and multivariate analyses. Our study suggests that, in patients with advanced HCC, morphological characteristics of the tumor may predict a good response to downstaging and an improved outcome after LT. Liver Transpl 16:289–299, 2010. © 2010 AASLD.
Strategy to prevent recurrent portal vein stenosis following interventional radiology in pediatric liver transplantation
Authors: Sanada Yukihiro , Kawano Youichi , Mizuta Koichi , Egami Satoshi , Hayashida Makoto , Wakiya Taiichi , Fujiwara Takehito , Sakuma Yasunaru , Hydo Masanobu , Nakata Manabu , Yasuda Yoshikazu , Kawarasaki Hideo
Published: January 2010

Portal vein complications after liver transplantation (LT) are serious complications that can lead to graft liver failure. Although the treatment of interventional radiology (IVR) by means of balloon dilatation for portal vein stenosis (PVS) after LT is an effective method, the high rate of recurrent PVS is an agonizing problem. Anticoagulant therapy for PVS is an important factor for preventing short-term recurrence following IVR, but no established regimen has been reported for the prevention of recurrent PVS following IVR. In our population of 197 pediatric patients who underwent living donor liver transplantation (LDLT), 22 patients (22/197, 11.2%) suffered PVS. In the 9 earliest patients, unfractionated heparin was the only anticoagulant therapy given following IVR. In the 13 more recent patients, 3-agent anticoagulant therapy using low-molecular-weight heparin, warfarin, and aspirin was employed. In the initial group of 9 patients, 5 patients (55.6%) suffered recurrent PVS and required repeat balloon dilatation. Among the 13 more recent patients, none experienced recurrent PVS (P = 0.002). In conclusion, our 3-agent anticoagulant therapy following IVR for PVS in pediatric LDLT can be an effective therapeutic strategy for preventing recurrent PVS. Liver Transpl 16:332–339, 2010. © 2010 AASLD.
A note on “resource flexibility with responsive pricing”
Authors: Bish Ebru K. , Liu Juqi , Bish Douglas R.
Published: January 2010

We revisit the capacity investment decision problem studied in the article “Resource Flexibility with Responsive Pricing” by Chod and Rudi [Operations Research 53, (2005) 532–548]. A monopolist firm producing two dependent (substitutable or complementary) products needs to determine the capacity of one flexible resource under demand risk so as to maximize its expected profit. Product demands are linear functions of the prices of both products, and the market potentials are random and correlated. We perform a comparative statics analysis on how demand variability and correlation impact the optimal capacity and the resulting expected profit. In particular, C&R study this problem under the following assumptions/approximations: (i) demand intercepts follow a bivariate Normal distribution; (ii) demand uncertainty is of an additive form; (iii) and under approximate expressions for the optimal capacity and optimal expected profit. We revisit Propositions 2, 3, 4, 5, and 10 of C&R without these assumptions and approximations, and show that these results continue to hold (i) for the exact expressions for the optimal expected profit and optimal capacity, and (ii) under any arbitrary continuous distribution of demand intercepts. However, we also show that the additive demand uncertainty is a critical assumption for the C&R results to hold. In particular, we provide a case of multiplicative uncertainty under which the C&R results (Propositions 2 and 3) fail. © 2010 Wiley Periodicals, Inc. Naval Research Logistics 2010
Scheduling with variable time slot costs
Authors: Wan Guohua , Qi Xiangtong
Published: January 2010

In this article, we study a class of new scheduling models where time slot costs have to be taken into consideration. In such models, processing a job will incur certain cost which is determined by the time slots occupied by the job in a schedule. The models apply when operational costs vary over time. The objective of the scheduling models is to minimize the total time slot costs plus a traditional scheduling performance measure. We consider the following performance measures: total completion time, maximum lateness/tardiness, total weighted number of tardy jobs, and total tardiness. We prove the intractability of the models under general parameters and provide polynomial‐time algorithms for special cases with non‐increasing time slot costs.© 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010
Optimal control of a production‐inventory system with both backorders and lost sales
Authors: Benjaafar Saif , ElHafsi Mohsen , Huang Tingliang
Published: January 2010

We consider the optimal control of a production inventory‐system with a single product and two customer classes where items are produced one unit at a time. Upon arrival, customer orders can be fulfilled from existing inventory, if there is any, backordered, or rejected. The two classes are differentiated by their backorder and lost sales costs. At each decision epoch, we must determine whether or not to produce an item and if so, whether to use this item to increase inventory or to reduce backlog. At each decision epoch, we must also determine whether or not to satisfy demand from a particular class (should one arise), backorder it, or reject it. In doing so, we must balance inventory holding costs against the costs of backordering and lost sales. We formulate the problem as a Markov decision process and use it to characterize the structure of the optimal policy. We show that the optimal policy can be described by three state‐dependent thresholds: a production base‐stock level and two order‐admission levels, one for each class. The production base‐stock level determines when production takes place and how to allocate items that are produced. This base‐stock level also determines when orders from the class with the lower shortage costs (Class 2) are backordered and not fulfilled from inventory. The order‐admission levels determine when orders should be rejected. We show that the threshold levels are monotonic (either nonincreasing or nondecreasing) in the backorder level of Class 2. We also characterize analytically the sensitivity of these thresholds to the various cost parameters. Using numerical results, we compare the performance of the optimal policy against several heuristics and show that those that do not allow for the possibility of both backordering and rejecting orders can perform poorly.© 2010 Wiley Periodicals, Inc. Naval Research Logistics 2010
PA66/PA12/clay based nanocomposites: morphology and physical properties
Authors: Besco Stefano , Lorenzetti Alessandra , Roso Martina , Modesti Michele
Published: January 2010

The structure and the physical properties of several polyamide 66 (PA66)/polyamide 12 (PA12) blends containing different amounts of the two polymers and obtained by melt‐blending have been investigated. A low amount of organically‐modified layered silicate (OMLS, 4 wt%) has also been introduced in order to further improve the physical properties and, in particular, to evaluate its effect on the blends' structure and components' miscibility. The microstructure and morphology of all the composites were analyzed by means of X‐Ray diffraction (WAXD), transmission electron microscopy (TEM), and high resolution scanning electron microscopy (SEM), while the macroscopic scale properties (mechanical behavior and water adsorption) were assessed in order to investigate and understand the materials' structure–properties relationships. The partial miscibility of PA66 and PA12, with phase separation depending on blend composition, has been confirmed. The results also underlined the possibility to tailor the behavior of polymer blends in terms of mechanical water adsorption properties by varying the amount of PA12, added to PA66 with and without the addition of the OLMS. The effectiveness of the clay in modifying the components' miscibility as well as its tendency to segregate preferentially within separate PA66 domains have been assessed. WAXD results showed opposite effects of PA12 and clay on the crystallization behavior of PA66, an aspect that has also been deepened in another paper by the same authors discussing the results of the complete thermal characterization. Copyright © 2010 John Wiley & Sons, Ltd.
Electrochemical impedance characterization and photovoltaic performance of N719 dye‐sensitized solar cells using quaternized ammonium iodide containing polyfluorene electrolyte solutions
Authors: Lee Rong‐Ho , Huang Yu‐Wei , Chang Jhih‐Wei , Hwang Jenn‐Chiu , Chen Yung‐Chung , Jeng Ru‐Jong
Published: January 2010

This study develops a series of titanium oxide electrode‐based N719 dye‐sensitized solar cells (DSSCs) using quaternized ammonium iodide containing main‐chain and star‐shaped polyfluorene (MPF‐E and SPF‐E) electrolyte solutions. The electrochemical impedance and photovoltaic properties of the polyfluorene electrolyte‐based DSSCs were studied and compared to those of the poly(ethylene oxide) (PEO) electrolyte‐based DSSCs. As with the PEO electrolyte‐based DSSCs, the recombination impedance increased with increase in the polymer content for the MPF‐E electrolyte‐based DSSCs, whereas the photovoltaic performance did otherwise. Nevertheless, the reduction in the photovoltaic properties was not significant for the SPF‐E electrolyte‐based DSSCs. The electrochemical impedance and photovoltaic properties of the different polymer‐based DSSCs are also discussed as a function of the polymer concentration. Copyright © 2010 John Wiley & Sons, Ltd.
Newly emerging applications of halloysite nanotubes: a review
Authors: Du Mingliang , Guo Baochun , Jia Demin
Published: January 2010

Halloysite nanotubes (HNTs) are types of naturally occurring 1:1 clays with nanotubular structures and similar chemical composition to kaolin. Due to various characteristics such as nanoscale lumens, high length‐to‐diameter ratio, relatively low hydroxyl group density on the surface, etc., numerous exciting applications have been discovered for this unique, cheap and abundantly deposited clay. After briefly summarizing applications in controlled release, nanotemplating and sorption, we emphasize the applications of HNTs in the fabrication of polymer nanocomposites. The unique structures and performance of HNT‐incorporated polymer nanocomposites processed by various routes are described. The results suggest that these nanocomposites exhibit remarkable performance such as reinforcing effects, enhanced flame retardancy and reduced thermal expansion. Accordingly, HNTs should be of interest in the area of polymer nanocomposites for structural and functional applications. Copyright © 2010 Society of Chemical Industry
Ionic polymer–metal composite mechanoelectrical transduction: review and perspectives
Authors: Pugal Deivid , Jung Kwangmok , Aabloo Alvo , Kim Kwang J
Published: January 2010

This paper presents a comprehensive review of the use of ionic polymer‐metal composite (IPMC) materials as mechanoelectrical transducers. Recently increasing emphasis has been put on the research of IPMCs as displacement or velocity sensors for various applications. This has resulted in various theories and models to describe the mechanoelectrical transduction phenomenon. The paper gives an overview of the proposed transduction principles, developed models and the latest applications. In more detail, the history of IPMC materials, the physics and the electrochemistry behind the mechanoelectrical transduction, different black‐box and gray‐box models, and novel real‐world mechatronics‐related applications are discussed throughout the paper. However, despite the latest advancements in the research of IPMC transduction, there is still a certain amount of controversy regarding some of the IPMC sensorial properties. For instance, it has been noticed by several authors that there is a signal delay when bending an IPMC. The general understanding of the physical principles about regular IPMC mechanoelectrical transduction is rather good. In the last section of the paper novel results are presented for copper‐coated IPMC materials. Apparently the electrochemistry behind the transduction for copper‐coated IPMCs is significantly different. Besides ionic diffusion, chemical reactions on the electrodes also occur and dominate the actuation process. Experimental results show some promising opportunities for designing new copper‐coated IPMC‐based sensors. Copyright © 2010 Society of Chemical Industry
An investigation of the effect of silane water‐crosslinking on the properties of poly(L‐lactide)
Authors: Han Changyu , Bian Junjia , Liu Hao , Han Lijing , Wang Shusheng , Dong Lisong , Chen Shan
Published: January 2010

A silane‐grafting water‐crosslinking approach was developed to crosslink poly(L‐lactide) (PLLA) by grafting vinylalkoxysilane onto PLLA using dicumyl peroxide, followed by silane hydrolysis to form siloxane linkages between PLLA chains. The degree of silane grafting onto PLLA was qualitatively characterized using Fourier transform infrared spectroscopy and quantitatively determined using inductively coupled plasma mass spectrometry. Crosslinked PLLA films were obtained by curing of silane‐grafted PLLA in hot water. Gel fractions were evaluated in order to calculate the crosslinking reaction kinetics and crosslinking density. Various techniques were used to investigate the effect of silane water‐crosslinking on the thermomechanical properties, hydrolysis resistance and biodegradation of PLLA. In addition to an improvement in thermal stability and mechanical properties, hydrolysis resistance was significantly enhanced as a result of silane water‐crosslinking of PLLA. Moreover, the biodegradation of silane water‐crosslinked PLLA was retarded compared with neat PLLA. Copyright © 2010 Society of Chemical Industry
Micellar behavior of well‐defined polystyrene‐based block copolymers with triethoxysilyl reactive groups and their hydrolysis–condensation
Authors: Gamys Cé Guinto , Beyou Emmanuel , Bourgeat‐Lami Elodie
Published: January 2010

Block copolymers of acryloxy propyl triethoxysilane and styrene were prepared through nitroxide‐mediated polymerization using alkoxyamine initiators based on N‐tert‐butyl‐1‐diethylphosphono‐2,2‐dimethylpropyl nitroxide. The copolymers were characterized by 1H NMR, size exclusion chromatography and differential scanning calorimetry. Their micellar behavior in dioxane/methanol solutions was examined through static light scattering and transmission electron microscopy (TEM). TEM indicated the successful formation of spherical micelles which were subsequently frozen by the sol–gel process. Hydrolysis–condensation of the reactive ethoxysilyl side groups was followed by FTIR, 1H NMR, and 29Si NMR. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 784–793, 2010
Effects of tetracarboxylic dianhydrides on the properties of sulfonated polyimides
Authors: Chen Xinbing , Chen Kangcheng , Chen Pei , Higa Mitsuru , Okamoto Ken‐Ichi , Hirano Tetsuji
Published: January 2010

A series of sulfonated polyimides (SPIs) were synthesized from a sulfonated diamine of 4,4′‐bis(4‐aminophenoxy) biphenyl‐3,3′‐disulfonic acid (BAPBDS), common nonsulfonated diamines, and various tetracarboxylic dianhydrides including 1,4,5,8‐naphthalene tetracarboxylic dianhydride (NTDA), 3,4,9,10‐perylene tetracarboxylic dianhydride (PTDA), 4,4′‐binaphthyl‐1,1′,8,8′‐tetracarboxylic dianhydride (BTDA), 4,4′‐ketone dinaphthalene 1,1′,8,8′‐tetracarboxylic dianhydride (KDNTDA), and isophthatic dinaphthalene 1,1′,8,8′‐tetracarboxylic dianhydride (IPNTDA). Their membrane properties were investigated to clarify the effects of the dianhydrides. They displayed reasonably high mechanical properties, thermal stability, and proton conductivity. The dianhydrides with flexible and non‐coplanar structure (IPNTDA > KDNTDA > BTDA) led to the better solubility of the SPIs than those with rigid and coplanar one (NTDA, PTDA). The dianhydride with the smaller molecular weight led to the larger value of the number of sorbed water molecules per sulfonic acid group (λ) in membrane, that is, NTDA (λ: 17) > PTDA (15) > BTDA (14) > KDNTDA (12) > IPNTDA (10), and as a result let to the larger proton conductivity in water. All of the BAPBDS‐based SPIs showed the anisotropy in membrane swelling and in proton conductivity, of which the degree hardly depended on the dianhydride moieties. The water stability of SPI membranes against the aging in water at 130 °C for 192 h was in the order, PTDA = NTDA ≧ BTDA > KDNTDA > IPNTDA. The hydrolysis stability of polymer chain was similar between the BTDA‐ and KDNTDA‐based SPIs. These results are discussed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 905–915, 2010
The preparation of amphiphilic core‐shell nanospheres by using water‐soluble macrophotoinitiator
Authors: Li Shurun , Deng Jianping , Yang Wantai
Published: January 2010

The amphiphilic poly(AM‐co‐SA)‐ITXH macrophotoinitiator was synthesized by precipitation photopolymerization under UV irradiation with isopropylthioxanthone (ITX) as free radical photoinitiator. A novel method has been developed to prepare amphiphilic core‐shell polymer nanospheres via photopolymerization of methyl methacrylate (MMA) in aqueous media, with amphiphilic copolymer macrophotoinitiator poly(AM‐co‐SA)‐ITXH. During polymerization, the amphiphilic macroradicals underwent in situ self‐assembly to form polymeric micelles, which promoted the emulsion polymerization of the monomer. Thus, amphiphilic core‐shell nanospheres ranging from 70 to 140 nm in diameter were produced in the absence of surfactant. The conversion of the monomer, number average molecular weights (Mn), and particle size were found to be highly dependent on the macrophotoinitiator and monomer concentration. The macrophotoinitiator and amphiphilic particles were characterized by FTIR, UV‐vis, 1H NMR, TEM, DSC, and contact angle measurements. The results showed the particles had well‐defined amphiphilic core‐shell structure. This new method is scientifically and technologically significant because it provides a commercially viable route to a wide variety of novel amphiphilic core‐shell nanospheres. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 936–942, 2010
Living/controlled cationic cyclopolymerization of divinyl ether with a cyclic acetal moiety: Synthesis of poly(vinyl ether)s with high glass transition temperature based on incorporation of cyclized main chain and cyclic side chains
Authors: Hashimoto Tamotsu , Takagi Hiromi , Hasegawa Yuko , Matsui Haruki , Urushisaki Michio , Sakaguchi Toshikazu
Published: January 2010

Cationic cyclopolymerization of 2‐methyl‐5,5‐bis(vinyloxymethyl)‐1,3‐dioxane (1), a divinyl ether with a cyclic acetal group, was investigated with the HCl/ZnCl2 initiating system in toluene and methylene chloride at −30 °C. The reaction proceeded quantitatively to give gel‐free, soluble polymers in organic solvents. The number‐average molecular weight (Mn) of the polymers increased in direct proportion to monomer conversion, and further increased on addition of a fresh monomer feed to the almost completely polymerized reaction mixture, indicating that the polymerization proceeded in living/controlled manner. The contents of the unreacted vinyl groups in the produced soluble polymers were less than ∼3 mol %, and therefore, the degree of cyclization was determined to be ∼97%. In contrast, the pendant cyclic acetal groups remained intact in the polymers under the present cationic polymerization conditions. These facts show that cyclopolymerization of 1 almost exclusively occurred and the poly(vinyl ether)s with the cyclized repeating units and cyclic pendant acetal rings were obtained. Glass transition temperature (Tg) and thermal decomposition temperature (Td) of poly(1) (Mn = 7870, Mw/Mn = 1.57) were found to be 166 and 338 °C, respectively, indicating that poly(1) had high Tg and high thermal stability. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 952–958, 2010
Controlled ring‐opening polymerization of lactide by bis‐sulfonamide/amine associations: Cooperative hydrogen‐bonding catalysis
Authors: Alba Aurélie , Schopp Aurélia , De Sousa Delgado Anne‐Paula , Cherif‐Cheikh Roland , Martín‐Vaca Blanca , Bourissou Didier
Published: January 2010

The bis‐sulfonamide m‐C6H4(SO2NHPh)2 efficiently promotes the ring‐opening polymerization of lactide when combined with tertiary amines, such as N,N‐dimethylaminopyridine. Polylactides of controlled molecular weights (Mn up to 17,700 g mol−1) and very narrow molecular weight distributions (Mw/Mn < 1.11) are obtained under mild conditions and in a living fashion. The reaction takes place through a bifunctional mechanism involving activation of both the alcohol and the monomer. Modulation of the sulfonamide component supports cooperative dual hydrogen‐bonding of lactide involving the two (SO2NHAr) moieties. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 959–965, 2010
Hypervalent iodine‐mediated direct azidation of polystyrene and consecutive click‐type functionalization
Authors: Tsarevsky Nicolay V.
Published: January 2010

Polystyrene was directly azidated in 1,2‐dichloroethane or chlorobenzene using a combination of trimethylsilyl azide and a hypervalent iodine (III) compound, (diacetoxyiodo)benzene. 2D NMR HMBC experiments indicated that the azide groups were attached to the polymer backbone and also possibly to the aromatic pendant groups. The amount of introduced azide groups was estimated by semi‐quantitative IR spectroscopy and elemental analysis. Approximately 1 in every 11 styrene units could be modified by using a ratio of hypervalent iodine compound to trimethylsilyl azide to styrene units of 1:2.1:1 at 0 °C for 4 h followed by heating to 50 °C for 2 h in chlorobenzene. The azidated polymers were further used as backbone precursors in the synthesis of polymeric brushes with hydrophilic side chains via a copper‐catalyzed click grafting‐onto reaction with poly(ethylene oxide) monomethyl ether 4‐pentynoate. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 966–974, 2010
Crystallization‐induced aging in poly(trimethylene terephthalate)/ poly(ethylene oxide terephthalate) segmented block copolymers
Authors: Yao Chenguang , Yang Guisheng
Published: January 2010

A new type poly(ether–ester) based on poly(trimethylene terephthalate) as rigid segments and poly(ethylene oxide terephthalate) as soft segments was synthesized and its aging behavior were investigated. Different from other polymer, the segmented block copolymers exhibited a unique aging mechanism. That is, the degradation of mechanical property within short term annealing was due to the overgrown crystals and dramatically increased crystallinity, which was proved by field emission scanning electron microscope (FE‐SEM) and differential scanning calorimetry (DSC), respectively. The deterioration in mechanical property after long term annealing was the results of both the increase in crystallinity and the decrease in molecular weight. Moreover, FE‐SEM showed many interesting flower‐like crystals presented on the surface of annealed sample. The flower‐like crystals consist of several radialized petal‐like arms and a more densely packed center, which has been seldom found in polymer bulk. Wide‐angle x‐ray diffraction results showed that the copolymer has the same crystal structure as PTT. Such poly(ether–ester) or its blends with other polymer could be suitable for rapid degradable products, such as package and vessel. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 411–416, 2010
Thermal and mechanical properties of a dendritic hydroxyl‐functional hyperbranched polymer and tetrafunctional epoxy resin blends
Authors: Zhang Jin , Guo Qipeng , Fox Bronwyn
Published: January 2010

Blends of a tetrafunctional epoxy resin, tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM), and a hydroxyl‐functionalized hyperbranched polymer (HBP), aliphatic hyperbranched polyester Boltorn H40, were prepared using 3,3′‐diaminodiphenyl sulfone (DDS) as curing agent. The phase behavior and morphology of the DDS‐cured epoxy/HBP blends with HBP content up to 30 phr were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). The phase behavior and morphology of the DDS‐cured epoxy/HBP blends were observed to be dependent on the blend composition. Blends with HBP content from 10 to 30 phr, show a particulate morphology where discrete HBP‐rich particles are dispersed in the continuous cured epoxy‐rich matrix. The cured blends with 15 and 20 phr exhibit a bimodal particle size distribution whereas the cured blend with 30 phr HBP demonstrates a monomodal particle size distribution. Mechanical measurements show that at a concentration range of 0–30 phr addition, the HBP is able to almost double the fracture toughness of the unmodified TGDDM epoxy resin. FTIR displays the formation of hydrogen bonding between the epoxy network and the HBP modifier. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 417–424, 2010
Solubility and partial molar volume of carbon dioxide and ethane in crosslinked poly(ethylene oxide) copolymer
Authors: Ribeiro Cláudio P. , Freeman Benny D.
Published: January 2010

Experimental solubility and sorptive dilation data are reported for carbon dioxide and ethane in a crosslinked poly(ethylene oxide) (XLPEO) rubbery copolymer. Five different temperatures (253 ≤ T(K) ≤ 308) were considered, with a maximum gas pressure of 2.09 MPa (20.6 atm). The polymer was prepared by photopolymerization of a solution containing 70 wt % poly(ethylene glycol) methyl ether acrylate (PEGMEA) and 30 wt % poly(ethylene glycol) diacrylate (PEGDA). Sorption isotherms were described by the Flory‐Huggins model. For each gas, the Flory‐Huggins interaction parameter was a decreasing function of temperature and did not show a composition dependence. Dilation and sorption data were combined to calculate the partial molar volume (PMV) of the gases in the polymer, which was an increasing function of temperature. Based on a comparison with literature data for a XLPEO homopolymer prepared from pure PEGDA over the same range of operating conditions, an effect of the network composition on both gas solubility and PMV was found. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 456–468, 2010
Relations between the aspect ratio of carbon nanotubes and the formation of percolation networks in biodegradable polylactide/carbon nanotube composites
Authors: Wu Defeng , Wu Liang , Zhou Weidong , Sun Yurong , Zhang Ming
Published: January 2010

The biodegradable polylactide composites containing carbon nanotubes (CNTs) with high aspect ratio (HAR) and low aspect ratio (LAR) were prepared by melt mixing. The physical properties of those two systems were characterized in terms of rheology, conductivity, and mechanical properties for establishing preliminary structure–property relations. Several viscoelastic models were then used to further describe the relations between aspect ratio and percolation network of CNTs. The results show that these two CNTs present different structural characteristics in the polylactide (PLA) matrix during melt mixing: the LAR CNTs are far stiffer than the HAR CNTs. At low loading levels, the former is dispersed as bent fibers or their small bundles, whereas the latter is dispersed as self‐entangled flocs, presenting far larger hydrodynamic radius than the former. At high loading levels, both are dispersed as flocs due to strong tube–tube interactions. However, the two CNTs show approximate average floc size and mesh size because they present same rigid length and effective aspect ratio. At identical loadings, therefore, the HAR CNTs have more total number of flocs than that of the LAR CNTs, forming network with more compact structure and imparting higher contributions to properties of the composites as a result. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 479–489, 2010
Multicolor single‐layer electroluminescence device using poly(L‐glutamate) for hole transport
Authors: Hiejima Toshihiro , Takamizawa Yosuke , Tanaka Yoshinori , Ueda Kenji , Uchida Takayuki
Published: January 2010

Helical poly(L‐glutamate) with carbazole (Cz) side chains (PCELG) was synthesized as a hole‐transport host material for a dye‐doped polymer electroluminescence (EL) device. The main‐ and side‐chain conformations were investigated by a combination of polarized infrared spectroscopy and semiempirical quantum chemical calculation. In an electrically poled PCELG crystalline film, the main chain was found to assume a right‐handed α‐helical conformation with an order parameter of ∼0.8. The Cz plane at the terminal side chain is inclined by about 44° toward the helical axis, creating a regular stacked structure conforming to the rigid α‐helical backbone. The principal EL characteristics of these devices were determined and compared with those of devices made with poly(N‐vinyl carbazole) (PVCz). For green and blue light, EL devices using PCELG exhibited luminance efficiencies comparable to those using PVCz. To the best of our knowledge, this was the first demonstration of primary colors emitted by an organic EL device with a polypeptide hole‐transport host material. The experimental results suggested that the total concentration and spatial arrangement of the Cz groups play an important role in determining the EL characteristics of dye‐doped polymer EL devices. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 496–502, 2010
Preface: Phys. Status Solidi C 7/1
Authors: Briot Olivier , Hoffmann Axel , Nanishi Yasushi , Ponce Fernando A. , Guest Editors
Published: January 2010

Symposium J of the E‐MRS 2009 Spring Meeting covered the diversity of the current nitride research ranging from optical, electrical and characterization over growth to processing and devices of nitride materials. There were many excellent talks which provided a nice spectrum about the state‐of‐the‐art of growth and devices based on InN. In an invited talk by Martin Stutzmann, Technische Universität München, the latest developments of GaN‐based sensors were discussed, especially their applications in biology. Highlights of the meeting were, on one hand, new developments of high power light emitting diodes (LEDs). These invited talks were given for UV LEDs by Asif Khan, University of South Carolina, for visible LEDs by Werner Goetz, Philips Lumileds, and for the green light emitters by Christian Wetzel, Rensselaer Polytechnic Institute. On the other hand, Adrian Avramescu, OSRAM Opto Semiconductors presented 500 nm electrically driven InGaN‐based laser diodes and demonstrated that quality improvements of InGaN quantum wells with high indium content as well as an efficient carrier injection makes it possible to achieve lasing up to a wavelength of 500 nm. Acentral contribution of the present proceedings is the Feature Article by Sandra Ruffenach et al. on recent advances in metal organic vapour phase epitaxy (MOVPE) growth of InN [1].

The symposium venue had a very pleasant surrounding and was convenient for the participants. The open atmosphere enabled a lot of detailed discussions. In the framework of European research, a major purpose of the meeting was to stimulate the generation of new projects and goals and to promote informal scientific exchange (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simple robust control structures based on the model‐following concept–A theoretical analysis
Authors: Osypiuk R.
Published: January 2010

The paper deals with three robust control systems that may be regarded as a part of the model‐following control (MFC) family. The systems are easy‐to‐synthesize control structures, thus offering an alternative to the low‐robust single‐loop PID system, to the relatively difficult‐to‐synthesize internal‐model control structures, or to complex adaptive systems. A basic comparative theoretical and computational analysis of properties exhibited by the presented control structures is given. Also, recommendations as to practical implementation are provided. The solutions presented in the paper have found some application, e.g. in force/position control for an industrial robotic manipulator, temperature control of electro‐heated furnaces with highly varying parameters, and oxide content control in a steam boiler. Owing to the interesting robustness properties displayed by MFC strict requirements on quality of controlled processes that are both strongly nonlinear and time variant have been met. Copyright © 2010 John Wiley & Sons, Ltd.
Fault‐tolerant adaptive control allocation schemes for overactuated systems
Authors: Casavola Alessandro , Garone Emanuele
Published: January 2010

This paper presents a fault‐tolerant adaptive control allocation scheme for overactuated systems subject to loss of effectiveness actuator faults. The main idea is to use an ‘ad hoc’ online parameters estimator, coupled with a control allocation algorithm, in order to perform online control reconfiguration whenever necessary. Time‐windowed and recursive versions of the algorithm are proposed for nonlinear discrete‐time systems and their properties analyzed. Two final examples have been considered to show the effectiveness of the proposed scheme. The first considers a simple linear system with redundant actuators and it is mainly used to exemplify the main properties and potentialities of the scheme. In the second, a realistic marine vessel scenario under propeller and thruster faults is treated in full details. Copyright © 2010 John Wiley & Sons, Ltd.
Effects of Galla chinensis on the surface topography of initial enamel carious lesion: an atomic force microscopy study
Authors: Zhang Ling‐Lin , Li Ji‐Yao , Zhou Xue‐Dong , Cui Fu‐Zhai , Li Wei
Published: January 2010

To investigate the effect of Galla chinensis on the surface topography of initial enamel carious lesion, atomic force microscope (AFM) was used, and it was a new AFM application in enamel de‐/remineralization research. Bovine sound enamel slabs were demineralized to produce initial carious lesion in vitro. Then, the lesions were exposed to a pH‐cycling regime for 12 days. Each daily cycle included 4×1 min applications with one of three treatments: negative control group: deionized water; positive control group: 1 g/L aqueous solutions of NaF; experimental group: 4 g/L aqueous solutions of G. chinensis extract (GCE). The surface topography and roughness were investigated on the enamel slabs before and after pH‐cycling by AFM. 3D AFM images revealed the surface topographical changes of GCE‐treated enamel. Significant difference existed before and after the pH‐cycling among the groups. AFM offers a powerful tool for enamel de‐/remineralization research. The surface roughness results provide the evidences to remineralization of carious lesion, and indicate the potential of G. chinensis in promoting the remineralization. G. chinensis may become one more promising agent for caries prevention. SCANNING 31: 195–203, 2009. © 2010 Wiley Periodicals, Inc.
Remarkable effect of pre‐organization on the self assembly in chiral liquid crystals
Authors: Nishiyama Isa
Published: January 2010

In this article, liquid crystal phases possessing a helical molecular assembly, including frustrated three dimensional (3D) structures, are overviewed. Then, the chirality‐originated superstructures in liquid crystals studied by the author are reviewed. The importance of the concept of “pre‐organization” is highlighted, thus, molecular design producing a strong chiral effect has been proposed. Dichiral twin materials have been prepared systematically based on this concept, and correlation between molecular architectures and resulting frustrated liquid crustal phases, such as smectic blue, cubic, tetragonal smectic Q, and sponge phases, has been investigated. An electrically induced anisotropic birefringent structure in the chiral isotropic phase and a photoinduced 3D‐3D phase transition in the smectic Q phase are introduced as possible application on the basis of the frustrated chiral 3D structured liquid crystal phases. A new type of chiral effect inducing the structural anisotropy in the 3D cubic structure of soft material is also described. © 2010 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 340–355; 2009: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.200900029
The natural history of fibroids
Authors: Mavrelos D. , Ben‐Nagi J. , Holland T. , Hoo W. , Naftalin J. , Jurkovic D.
Published: January 2010

Objectives

Fibroids are common, hormone‐dependent, benign uterine tumors. They can cause significant morbidity and the symptoms depend largely on their size. The aim of this study was to describe the natural history of fibroids and identify factors that may influence their growth.

Methods

This was a retrospective longitudinal study of premenopausal women who were diagnosed with uterine fibroids on ultrasound examination. All women underwent at least two transvaginal ultrasound scans, which were all performed by a single operator. Fibroids were measured in three perpendicular planes and the mean diameter was calculated. The size and position of every individual fibroid was assessed and recorded on a computerized database. The volume of each fibroid was calculated using the formula for a sphere.

Results

A total of 122 women were included in the study. Their median age at the initial examination was 40 (range, 27–45) years. Seventy‐two (59.0%) were nulliparous and 74 (60.7%) had multiple fibroids. The median interval between the initial and final examination was 21.5 (range, 8–90) months. The median fibroid volume increased by 35.2% per year. Small fibroids (< 20 mm mean diameter) grew significantly faster than larger fibroids (P = 0.007). The median increase in size was significantly higher in cases of intramural fibroids (53.2 (interquartile range (IQR), 11.2–217)%) than in subserous fibroids (25.1 (IQR, 1.1–87.1)%) and submucous fibroids (22.8 (IQR, − 11.7 to 48.3)%) (P = 0.012). Multivariate analysis retained only fibroid size at presentation as an independent predictor of fibroid growth.

Conclusion

The growth of fibroids in premenopausal women is influenced by the tumor's size at presentation. Copyright © 2010 ISUOG. Published by John Wiley & Sons, Ltd.