bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Aggregation Behaviors of Well‐Defined Thermoresponsive Pentablock Terpolymers With Tunable LCST
Authors: Wu Yufeng , Liu Xingli , Wang Yu , Guo Zanru , Feng Yujun 
Published: June 2012

AbstractA series of thermoresponsive pentablock terpolymers, poly(N‐isopropylacrylamide)‐b‐poly(ethylene oxide)‐b‐poly(propylene oxide)‐b‐poly(ethylene oxide)‐b‐poly(N‐isopropylacrylamide), is prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization. The effect of NIPAM and PPO block lengths on lower critical solution temperature (LCST), critical micelle concentration (cmc), and aggregation number (Nagg) is investigated via UV–Vis spectroscopy and steady‐state fluorescence spectroscopy. The results show that upon increasing the block lengths, LCST and cmc decrease, while Nagg increases. TEM observation shows that associated spherical‐like particles are evidenced below the LCST of the terpolymers, and regular or irregular spherical micelles or even intermicellar aggregates are observed above the LCST.
Compounding of MWCNTs with PS in a Twin‐Screw Extruder with Varying Process Parameters: Morphology, Interfacial Behavior, Thermal Stability, Rheology, and Volume Resistivity
Authors: Sathyanarayana Shyam , Olowojoba Ganiu , Weiss Patrick , Caglar Burak , Pataki Bernadeth , Mikonsaari Irma , Hübner Christof , Henning Frank 
Published: June 2012

Abstract1, 2, 3, 5, and 7.5 wt% MWCNTs are incorporated into PS in a twin‐screw extruder at varying speeds, throughputs and extruder barrel temperatures. Increased SME at enhanced processing speeds seems to have the single largest effect in enhancing dispersion. A relative evaluation of PS/MWCNT interactions indicate an interfacial layer growth of 24% for 2 wt% MWCNT at 1100 rpm compared to 18% growth at 500 rpm. Raman analysis does not show an MWCNT peak shift but a constant increase in FWHM is observed irrespective of the MWCNT content. A significant enhancement of thermal stability occurs up to 2 wt% MWCNT loading while 1–2 wt% shows the rheological threshold. The volume resistivity decreases dramatically in a 2 wt% sample processed at 1100 rpm compared to those processed at 500 rpm.magnified image
Neuromuscular properties of the thigh muscles in patients with ehlers–danlos syndrome
Authors: Gerrits Karin H.L. , Voermans Nicol C. , de Haan Arnold , van Engelen Baziel G. 
Published: June 2012

AbstractIntroduction: Ehlers–Danlos syndrome (EDS), a connective tissue disorder, may lead to impaired contractile function of lower limb muscles. Methods: To test this hypothesis and to understand the possible mechanisms involved, isometric function of the thigh muscles was investigated at different joint angles (30°, 60°, and 90° of knee flexion) in 7 tenascin‐X (TNX)‐deficient EDS patients. Results: There was reduced maximal voluntary torque of the knee extensors (but not knee flexors) across all joint angles in the patients. Time to reach maximal rate of torque development was delayed, and voluntary activation capacity was reduced in patients compared with controls, particularly at 30°. Conclusions: EDS is associated with muscle weakness, most likely due to increased compliance of the series‐elastic component of muscle tissue and failure of maximal voluntary muscle activation. Further research is required to understand the influence of reduced voluntary activation on the severe fatigue reported by EDS patients. Muscle Nerve, 2013
Electrophysiological study of medial and lateral branches of the superficial radial nerve
Authors: Cappellari Alberto M. , Bona Alberto R. , Lukasova Katerina 
Published: June 2012

AbstractIntroduction: In this study we sought to establish a new technique for nerve conduction study (NCS) of medial and lateral branches of the superficial radial nerve (SRN). Methods: Antidromic NCS were performed on 60 healthy subjects, recording the sensory nerve action potential (SNAP) from the dorsomedial and dorsolateral aspects of the phalanx of the thumb. The main trunk of SRN was also investigated. Results: SNAPs were easily recorded in all subjects, and normative latency and amplitude data were collected. Conclusions: We propose a simple and reliable technique to investigate nerve conduction of the terminal branches of the SRN, which could be useful in some focal and systemic pathologies. Muscle Nerve, 2013
Near‐infrared spectroscopy during exercise and recovery in children with juvenile dermatomyositis
Authors: Habers G. Esther A. , De Knikker Rogier , Van Brussel Marco , Hulzebos Erik , Stegeman Dick F. , Van Royen Annet , Takken Tim 
Published: June 2012

AbstractIntroduction: We hypothesized that microvascular disturbances in muscle tissue play a role in the reduced exercise capacity in juvenile dermatomyositis (JDM). Methods: Children with JDM, children with juvenile idiopathic arthritis (clinical controls), and healthy children performed a maximal incremental cycloergometric test from which normalized concentration changes in oxygenated hemoglobin (Δ[O2Hb]) and total hemoglobin (Δ[tHb]) as well as the half‐recovery times of both signals were determined from the vastus medialis and vastus lateralis muscles using near‐infrared spectroscopy. Results: Children with JDM had lower Δ[tHb] values in the vastus medialis at work rates of 25%, 50%, 75%, and 100% of maximal compared with healthy children; the increase in Δ[tHb] with increasing intensity seen in healthy children was absent in children with JDM. Other outcome measures did not differ by group. Conclusions: The results suggest that children with JDM may experience difficulties in increasing muscle blood volume with more strenuous exercise. Muscle Nerve, 2013
Gram‐Schmidt orthogonalization: 100 years and more
Authors: Leon Steven J. , Björck Åke , Gander Walter 
Published: June 2012

SUMMARYIn 1907, Erhard Schmidt published a paper in which he introduced an orthogonalization algorithm that has since become known as the classical Gram‐Schmidt process. Schmidt claimed that his procedure was essentially the same as an earlier one published by J. P. Gram in 1883. The Schmidt version was the first to become popular and widely used. An algorithm related to a modified version of the process appeared in an 1820 treatise by P. S. Laplace. Although related algorithms have been around for almost 200 years, it is the Schmidt paper that led to the popularization of orthogonalization techniques. The year 2007 marked the 100th anniversary of that paper. In celebration of that anniversary, we present a comprehensive survey of the research on Gram‐Schmidt orthogonalization and its related QR factorization. Its application for solving least squares problems and in Krylov subspace methods are also reviewed. Software and implementation aspects are also discussed. Copyright © 2012 John Wiley & Sons, Ltd.
Validation of three coding algorithms to identify patients with end‐stage liver disease in an administrative database
Authors: Goldberg D , Lewis JD , Halpern SD , Weiner Mark , Lo Re Vincent 
Published: June 2012

ABSTRACTPurposeUse of administrative or population‐based databases for post‐marketing pharmacoepidemiology research in patients with end‐stage liver disease (ESLD) has been limited by the difficulty of accurately identifying such patients. Algorithms to identify patients with ESLD using ICD‐9‐CM codes have not been developed outside of the Veterans Affairs healthcare setting.MethodsWe queried electronic medical records at two tertiary care hospitals to identify patients with ICD‐9‐CM codes indicative of ESLD. Coding algorithms were developed to identify patients with confirmed ESLD, and these were tested to determine their positive predictive value (PPV).ResultsThe presence of one inpatient or outpatient ICD‐9‐CM code for: (i) cirrhosis; (ii) chronic liver disease, and (iii) a hepatic decompensation event yielded a PPV of 85.2% (167/196; 95% CI: 79.4%–89.9%). The PPV increased to 89.3% (150/168; 95% CI: 83.6%–93.5%) when the algorithm required two or more ICD‐9‐CM codes for a hepatic decompensation. However, an algorithm requiring only one ICD‐9‐CM code for (i) cirrhosis and (ii) a hepatic decompensation event, in the absence of a chronic liver disease code, yielded a PPV of 85.7% (30/35; 95% CI: 69.7%‐95.2%).ConclusionsA coding algorithm that includes at least one ICD‐9‐CM code for cirrhosis plus one ICD‐9‐CM code for a hepatic decompensation event has a high PPV for identifying patients with ESLD. The inclusion of at least two codes indicative of a hepatic decompensation event increased the PPV. This algorithm can be used in future epidemiologic studies to examine the outcomes of a variety of long‐term medical therapies in patients with ESLD. Copyright © 2012 John Wiley & Sons, Ltd.
Exploring large weight deletion and the ability to balance confounders when using inverse probability of treatment weighting in the presence of rare treatment decisions
Authors: Kilpatrick Ryan D. , Gilbertson Dave , Brookhart M. Alan , Polley Eric , Rothman Kenneth J. , Bradbury Brian D. 
Published: June 2012

ABSTRACTPurposeWhen medications are modified in response to changing clinical conditions, confounding by indication arises that cannot be controlled using traditional adjustment. Inverse probability of treatment weights (IPTWs) can address this confounding given assumptions of no unmeasured confounders and that all patients have a positive probability of receiving all levels of treatment (positivity). We sought to explore these assumptions empirically in the context of epoetin‐alfa (EPO) dosing and mortality.MethodsWe developed a single set of IPTWs for seven EPO dose categories and evaluated achieved covariate balance, mortality hazard ratios, and confidence intervals using two levels of treatment model parameterization and weight deletion.ResultsWe found that IPTWs improved covariate balance for most confounders, but was not optimal for prior hemoglobin. Including more predictors in the treatment model or retaining highly weighted individuals resulted in estimates closer to the null, although precision decreased.ConclusionWe chose to evaluate weights and covariate balance at a single time‐point to facilitate an empirical analysis of model assumptions. These same assumptions are applicable to a time‐dependent analysis, although empirical examination is not straight forward in that case. We find that the inclusion of rare treatment decisions and the high weights that result is needed for covariate balance under the positivity assumption. Removal of these influential weights can result in bias in either direction relative to the original confounding. It is therefore important to determine the reason for these rare patterns and whether inference is possible for all treatment levels. Copyright © 2012 John Wiley & Sons, Ltd.
Predictors of recall certainty of dates of analgesic medication use in pregnancy
Authors: Radin Rose G. , Mitchell Allen A. , Werler Martha M. 
Published: June 2012

ABSTRACTPurposeRecalled dates of medication use are difficult to validate, particularly for over‐the‐counter (OTC) medications. We evaluated mothers’ recall certainty as an approximation of the accuracy of their recalled exposures.MethodsWe used data from the Slone Epidemiology Center Birth Defects Study collected by retrospective interview of women about pregnancy medication use. For each medication reported, women were asked to report the dates of their use and how certain they were of their reported dates. For this analysis, 32 107 reports from 14 577 analgesic users were categorized as “high” or “low” recall certainty if they considered a reported date as exact or estimated, respectively. Patterns of analgesic use, maternal demographics, and health behaviors were explored as predictors of high recall certainty of dates of analgesic use. We used log‐binomial regression with the generalized estimating equations extension to account for multiple reports per subject in estimating prevalence ratios (PR) and 95% confidence intervals.ResultsRelative to episodes of short‐term routine use (≥4 times/week for ≤30 days), high recall certainty was more likely for episodes of a single dose (prescription PR = 1.92 (1.61, 2.27); OTC PR = 3.65 (3.03, 4.40)) and less likely for episodes of occasional use (prescription PR = 0.10 (0.05, 0.18); OTC PR = 0.65 (0.53, 0.79)). The association of chronic routine use with high recall certainty was inverse among prescription analgesics and positive among OTC analgesics (prescription PR = 0.56 (0.40, 0.80); OTC PR = 2.46 (1.92, 3.42)).ConclusionsSome characteristics that were associated with recall accuracy in previous studies were also associated with recall certainty in this study. Copyright © 2012 John Wiley & Sons, Ltd.
Assessing the effect of vaccine on spontaneous abortion using time‐dependent covariates Cox models
Authors: Xu Ronghui , Luo Yunjun , Chambers Christina 
Published: June 2012

ABSTRACTPurposeIn studying the safety of vaccine for influenza A (H1N1) given during pregnancy, spontaneous abortion (SAB) is one of the important points to consider. Because women may receive the vaccine any time during their pregnancy, evaluation of the effect of the vaccine on SAB should only take place after vaccination and in the risk window for SAB, that is, the first 20 weeks of gestation. In addition, when such studies are conducted through pregnancy registries where recruitment occurs after pregnancy recognition, the accrued subjects are left truncated in the sense that they are not followed from the start of pregnancy.MethodsAs previously reported, left truncation needs to be properly handled using survival analysis methods to avoid bias. In the context of time‐dependent vaccine exposure, a time‐dependent covariate Cox model can be used to simultaneously take into account the left truncation and the vaccine exposure timing.ResultsIn this communication, we illustrate the approach using the Vaccine and Medication in Pregnancy Surveillance System data. We explain in details how the model is fitted using different software.ConclusionsWe recommend survival analysis methods together with collection of necessary data to study the effects of vaccine on SAB. Copyright © 2012 John Wiley & Sons, Ltd.
Reporting of irradiance modeling relative prediction errors
Authors: Hoff Thomas E. , Perez Richard , Kleissl Jan , Renne David , Stein Joshua 
Published: June 2012

ABSTRACTMetrics used in assessing irradiance model accuracy, such as root mean square error and mean absolute error, are precisely defined. Their relative (%) counterpart, however, can be subject to interpretation and may cover a wide range of values for a given set of data depending on reporting practice. This note evaluates different approaches for the reporting of relative metrics quantifying the dispersion accuracy of a model and formulates recommendations for the most appropriate approach. Copyright © 2012 John Wiley & Sons, Ltd.
Unusual effect of molecular weight and concentration on thermoresponsive behaviors of well‐defined water‐soluble semirigid polymers
Authors: Liu Peng , Xie Helou , Tang Haoyu , Zhong Guanqun , Zhang Hailiang 
Published: June 2012

AbstractA series of water‐soluble semirigid thermoresponsive polymers with well‐defined molecular weights based on mesogen‐jacketed liquid crystal polymers (MJLCPs), poly[bis(N‐hydroxyisopropyl pyrrolidone) 2‐vinylterephthalate] (PHIPPVTA) have been synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization. Dynamic light scattering (DLS) revealed that the novel monomer and polymers have thermoresponsive properties with cloud point in the range between 10 and 90 °C. The cloud point was increased by 56.2 °C when the polymer molecular weight increased from 0.47 × 104 g mol−1 to 3.69 × 104 g mol−1. In addition, the cloud point of PHIPPVTA was decreased by 18.8 °C with the increase of polymer concentration from 5 to 10 mg mL−1. A slight increase (0.1–3.5 °C) of cloud point has been observed after knocking off the end‐groups of PHIPPVTA. Moreover, the cloud point of polymer increased with increasing of its molecular weight with or without the trithiocarbonate end‐groups, which showed the opposite trend comparing with other thermoresponsive polymers with flexible backbones. These polymers show a dramatic solvent isotopic effect that the cloud point in D2O was lower than in H2O. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Improving the control of styrene polymerization at 60 °C using a dialkylated α‐hydrogenated nitroxide
Authors: Guillaneuf Yohann , Lamps Jean‐Philippe , Catala Jean‐Marie , Gigmes Didier , Drockenmuller Eric 
Published: June 2012

AbstractA new dialkylated α‐hydrogenated linear nitroxide and the corresponding 1‐phenylethyl alkoxyamine were synthesized in two and three steps, respectively. The alkoxyamine was involved in the polymerization of styrene at 60 °C, and the in situ concentration of nitroxide was monitored by electron spin resonance spectroscopy. The enhanced characteristics of these new alkylated alkoxyamine and nitroxide (k = 1.5 × 10−4 s−1 and k = 5.7 × 104 L mol−1 s−1) yielded a monomer consumption one order of magnitude higher than styrene thermal polymerization. This resulted in well‐defined polystyrenes up to 70,000 g mol−1 and the observation of a control occurring through the establishment of the radical persistent effect, that is, ln([M]0/[M]) = t2/3. Experimentally determined kinetic constants were involved in PREDICI modelings to investigate the influence of temperature and initial alkoxyamine concentration on the kinetics as well as on the livingness and the controlled character of the polymerization. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Segmented block copolyesters using click chemistry
Authors: June Stephen M. , Bissel Philippe , Long Timothy E. 
Published: June 2012

AbstractCopper(I) catalyzed azide‐alkyne 1,3‐Huisgen cycloaddition reaction afforded the synthesis of triazole‐containing polyesters and segmented block copolyesters at moderate temperatures. Triazole‐containing homopolyesters exhibited significantly increased (∼40 °C) glass transition temperatures (Tg) relative to high temperature, melt synthesis of polyesters with analogous structures. Quantitative synthesis of azido‐terminated poly(propylene glycol) (PPG) allowed for the preparation of segmented polyesters, which exhibited increased solubility and mechanical ductility relative to triazole‐containing homopolyesters. Differential scanning calorimetry demonstrated a soft segment (SS) Tg near −60 °C for the segmented polyesters, consistent with microphase separation. Tensile testing revealed Young's moduli ranging from 7 to 133 MPa as a function of hard segment (HS) content, and stress at break values approached 10 MPa for 50 wt % HS segmented click polyesters. Dynamic mechanical analysis demonstrated an increased rubbery plateau modulus with increased HS content, and the Tg's of both the SS and HS did not vary with composition, confirming microphase separation. Atomic force microscopy also indicated microphase separated and semicrystalline morphologies for the segmented click polyesters. This is the first report detailing the preparation of segmented copolyesters using click chemistry for the formation of ductile membranes with excellent thermomechanical response. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Design, synthesis, photophysical, and electrochemical properties of DCM‐based conjugated polymers for light‐emitting devices
Authors: Vanjinathan Mahalingam , Lin Hong‐Cheu , Nasar A. Sultan 
Published: June 2012

AbstractA series of conjugated hyperbranched polymers, hyperbranched copolymers, and linear polymers containing 2‐pyran‐4‐ylidenemalononitrile (acceptor) and triphenylamine/fluorene (donor) units were synthesized and characterized by FTIR, 1H NMR, thermogravimetric analyses, differential scanning calorimetry, gel permeation chromatography, UV–visible, photoluminescence, and cyclic voltammetry measurements. All the polymers show red‐light emission in the range of 566–656 nm both in solution and in solid state. The quantum efficiency of the polymers was in the range of 56–82%. Among the six polymers synthesized, only polymers containing fluorene units show Tg and polymers based on triphenylamine not exhibit Tg. The band gap of these polymers were found to be reasonably low; hyperbranched copolymer containing fluorene unit shows lowest band gap of 2.18 eV due to the stabilization of LUMO energy level by the electron withdrawing CN groups. The thermal and solubility behavior of the polymers were found to be good. All the EL spectra of the devices (indium‐tin oxide/poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)/polymer/2,9‐dimethyl‐4,7‐diphenyl‐1,10‐phenanthroline/tris(8‐hydroxyquinoline)aluminum)/LiF/Al) show red‐light emission, and the device fabricated with P3 and P4 shows maximum luminance and luminous efficiency of 4104 cd m−2 and 0.55 cd Å−1 and 3696 cd m−2 and 0.47 cd Å−1, respectively, indicates that they had the best carrier balance. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Synthesis and properties of hyperbranched poly(ether sulfone)s prepared by self‐polycondensation of novel AB2 monomer
Authors: Jikei Mitsutoshi , Uchida Daisuke , Haruta Yuuki , Takahashi Yuuki , Matsumoto Kazuya 
Published: June 2012

AbstractHyperbranched poly(ether sulfone)s were prepared by the self‐polycondensation of the novel AB2 monomer, 4‐(3,5‐hydroxyphenoxy)‐4′‐fluorodiphenylsulfone. The high‐molecular‐weight polymers were isolated in good yields. The degree of branching (DB) of the resulting polymers was investigated by the preparation of dendritic and linear model compounds. The DB determined by gated decoupling 13C NMR measurements was in the range 0.17–0.41 and was dependent on the base used for the self‐polycondensation. It was found that cesium fluoride was an effective base to form the polymer having the DB of 0.41. The resulting hyperbranched poly(ether sulfone)s showed good solubility in organic solvents. The solubility and the glass transition temperature of the polymers were influenced by the terminal functional groups. The unique thermal crosslinking phenomenon was observed during the DSC measurements of the hydroxyl‐terminated hyperbranched poly(ether sulfone) under air condition. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Efficient polymer passivation of ligand‐stripped nanocrystal surfaces
Authors: Duong Jennifer T. , Bailey Mark J. , Pick Teresa E. , McBride Patrick M. , Rosen Evelyn L. , Buonsanti Raffaella , Milliron Delia J. , Helms Brett A. 
Published: June 2012

AbstractWater‐dispersible, polymer‐wrapped nanocrystals are highly sought after for use in biology and chemistry, from nanomedicine to catalysis. The hydrophobicity of their native ligand shell, however, is a significant barrier to their aqueous transfer as single particles. Ligand exchange with hydrophilic small molecules or, alternatively, wrapping over native ligands with amphiphilic polymers is widely employed for aqueous transfer; however, purification can be quite cumbersome. We report here a general two‐step method whereby reactive stripping of native ligands is first carried out using trialkyloxonium salts to reveal a bare nanocrystal surface. This is followed by chemically directed immobilization of a hydrophilic polymer coating. Polyacrylic acids, with side‐chain grafts or functional end groups, were found to be extremely versatile in this regard. The resulting polymer‐wrapped nanocrystal dispersions retained much of the compact size of their bare nanocrystal precursors, highlighting the unique role of monomer side‐chain functionality to serve as effective, conformal ligation motifs. As such, they are well poised for applications where tailored chemical functionality at the nanocrystal's periphery or improved access to their surfaces is desirable. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012