bluuebunny/crossref_metadata_2025_split huggingface dataset:
The origin of DC electrical conduction and dielectric relaxation in pristine and doped poly(3‐hexylthiophene) films
Authors: Singh Ramadhar , Singh Rajiv K. , Kumar Jitendra , Kant Rama , Kumar Vikram 
Published: April 2010

AbstractWe present here the evidence for the origin of dc electrical conduction and dielectric relaxation in pristine and doped poly(3‐hexylthiophene) (P3HT) films. P3HT has been synthesized and purified to obtain pristine P3HT polymer films. P3HT films are chemically doped to make conducting P3HT films with different conductivity level. Temperature (77–350 K) dependent dc conductivity (σdc) and dielectric constant (ε′(ω)) measurements on pristine and doped P3HT films have been conducted to evaluate dc and ac electrical conduction parameters. The relaxation frequency (fR) and static dielectric constant (ε0) have been estimated from dielectric constant measurements. A correlation between dc electrical conduction and dielectric relaxation data indicates that both dc and ac electrical conductions originate from the same hopping process in this system. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1047–1053, 2010
Hydrophobically modified poly(vinyl alcohol) using alkoxy‐substituted methyl gallate: Synthesis and rheology
Authors: Shedge Aarti S. , Wadgaonkar Prakash P. , Lele Ashish K. , Badiger Manohar V. 
Published: April 2010

AbstractHydrophobically modified poly(vinyl alcohol) (HMPVA) polymers were synthesized by potassium t‐butoxide‐catalyzed reaction of PVA with methyl 3,4,5‐tris(n‐octyloxy) benzoate (MGC8)/3,4,5‐tris(n‐dodecyloxy) benzoate (MGC12) and 1,3‐propane sultone. The concentration of 1,3‐propane sultone was kept constant at 10 mol % and that of MGC8 (2, 3, and 4 mol %)/MGC12 (2 and 3 mol %) was varied to obtain HMPVAs with different hydrophobic contents. The incorporation of MGC8/MGC12 and 1,3‐propane sultone onto HMPVA was confirmed by NMR spectroscopy. Rheological properties of aqueous solutions also confirmed the presence of hydrophobic and charged functional groups on HMPVAs. In the semidilute regime, the specific viscosity of HMPVAs followed concentration scaling that is typical of polyelectrolytes. At higher concentrations, the HMPVA solutions with 3 and 4 mol % of MGC8 exhibited large increase in specific viscosity. Oscillatory experiments on these solutions exhibited gel‐like behavior at polymer concentrations of 40–50 g/L. Confocal microscopy images of HMPVA with 4 mol % of MGC8 clearly indicated the existence of microgels. The tendency of formation of microgels further increased with increasing chain length of the hydrophobe, that is, with MGC12. These samples exhibited rheological behavior that is typical of soft solids and was therefore probed by the strain‐rate frequency superposition technique reported recently in the literature. HMPVAs with improved rheological properties show potential applications as thickeners in cosmetic creams, lotions and as drug carriers in pharmaceutical formulations. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1054–1063, 2010
Nonisothermal crystallization kinetics of poly (phenylene sulphide) in composites with a liquid crystalline polymer
Authors: Kalkar Arun K. , Deshpande Vineeta D. , Kulkarni Milind J. 
Published: April 2010

AbstractThe article deals with the melting and nonisothermal crystallization behavior of neat poly (phenylene sulphide) (PPS) and its composites with a thermotropic liquid crystalline polymer (TLCP)—Vectra A950, prepared by melt mixing and probed by differential scanning calorimetry. The various macrokinetic models namely, the Ozawa, the modified Avrami, the Tobin, and the Mo models were applied to describe the crystallization kinetics under nonisothermal conditions. The kinetic crystallizabilty of PPS/TLCP composites calculated using the approach of Ziabicki varies depending on these two composite composition‐induced effects. Similarly Mo model predicts that to obtain a higher degree of crystallizabilty for PPS/TLCP composites, a higher cooling rate should be used. The effective energy barrier based on the differential isoconversional method of Friedman is found to be an increasing function of relative degree of melt conversion. The effect is explained in terms of nucleation theory proposed by Wunderlich to crystallization of polymers. The Lauritzen–Hoffman parameters are estimated using G = 1/t0.5 effective activation energy equation proposed by Vyazovkin and Sbirrazzuoli. The Kg values estimated from latter equations are more comparable with values obtained using isothermal crystallization data than 1/t0.5 method. Furthermore, the kinetic analysis using this equation shows a regime transition from regime II to regime III for 100/00, 90/10, 80/20 PPS/TLCP composites, basically attributed to reduced mobility of PPS chains in composites. This regime II to III transition is accompanied by a morphological transition from defective spherulitic sheaf‐like structures to ordered sheaf‐like structures. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1070–1100, 2010
Stability of hierarchical lamellar morphologies formed in ABC star triblock copolymers
Authors: Xu Yuci , Li Weihua , Qiu Feng , Zhang Hongdong , Yang Yuliang , Shi An‐Chang 
Published: April 2010

AbstractThe stability of hierarchical lamellar morphologies formed in ABC star triblock copolymers, is studied using the self‐consistent mean‐field theory. The hierarchical lamellae consist of repeating period of the largest block A‐formed layer and B/C coformed layer where B and C domains are arranged alternatively. An angle, which is used to characterize the shifting magnitude between two neighbor B/C coformed layers, varies from 0 to 180 degrees. By comparing the free energy among the lamellar morphologies with various shift angle, their relative stability is analyzed. Our results show that the morphology with larger shift has lower entropic energy and higher internal energy. In general, the morphology with the largest shift of 180‐degree is stable compared with those with smaller shift as the entropic energy dominates the internal energy. However, the relative stability can be tuned by the interactions among the three components as well as their relative compositions. PACS numbers: 61.25.Hq, 64.60.Cn, 64.75.+g. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1001–1109, 2010
Synthesis and characterization of grafted/crosslinked proton conducting membranes based on amphiphilic PVDF copolymer
Authors: Roh Dong Kyu , Ahn Sung Hoon , Seo Jin Ah , Shul Yong Gun , Kim Jong Hak 
Published: April 2010

AbstractA novel graft copolymer consisting of a poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) backbone and poly(glycidyl methacrylate) side chains, that is, P(VDF‐co‐CTFE)‐g‐PGMA, was synthesized through atom transfer radical polymerization (ATRP) using CTFE units as a macroinitiator. Successful synthesis and microphase‐separated structure of the polymer were confirmed by 1H NMR, FTIR spectroscopy, and TEM. As‐synthesized P(VDF‐co‐CTFE)‐g‐PGMA copolymer was sulfonated by sodium bisulfite, followed by thermal crosslinking with sulfosuccinic acid (SA) via the esterification to produce grafted/crosslinked polymer electrolyte membranes. The IEC values continuously increased with increasing SA content but water uptake increased with SA content up to 10 wt %, above which it decreased again as a result of competitive effect between crosslinking and hydrophilicity of membranes. At 20 wt % of SA content, the proton conductivity reached 0.057 and 0.11 S/cm at 20 and 80 °C, respectively. The grafted/crosslinked P(VDF‐co‐CTFE)‐g‐PGMA/SA membranes exhibited good mechanical properties (>400 MPa of Young's modulus) and high thermal stability (up to 300 °C), as determined by a universal testing machine (UTM) and TGA, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1110–1117, 2010
Seeking informed consent to Phase I cancer clinical trials: identifying oncologists' communication strategies
Authors: Brown Richard , Bylund Carma L. , Siminoff Laura A. , Slovin Susan F. 
Published: April 2010

AbstractPurpose: Phase I clinical trials are the gateway to effective new cancer treatments. Many physicians have difficulty when discussing Phase I clinical trials. Research demonstrates evidence of suboptimal communication. Little is known about communication strategies used by oncologists when recruiting patients for Phase I trials. We analyzed audio recorded Phase I consultations to identify oncologists' communication strategies.Patients and Methods: Subjects were consecutive cancer patients from six medical oncologists attending one of three outpatient clinics at a major Cancer Center in the United States. Sixteen patients signed informed consent for audio recording of their consultations in which a Phase I study was discussed. These were transcribed in full and analyzed to identify communication strategies.Results: Six communication themes emerged from the analysis: (1) orienting, (2) educating patients, (3) describing uncertainty and prognosis, (4) persuading, (5) decision making, and (6) making a treatment recommendation. As expected, although there was some common ground between communication in Phase I and the Phase II and III settings, there were distinct differences.Conclusions: Oncologists used persuasive communication, made explicit recommendations, or implicitly expressed a treatment preference and were choice limiting. This highlights the complexity of discussing Phase I trials and the need to develop strategies to aid oncologists and patients in these difficult conversations. Patient centered communication that values patient preferences while preserving the oncologist's agenda can be a helpful approach to these discussions. Copyright © 2010 John Wiley & Sons, Ltd.
Simulation of two‐dimensional Mo photonic crystal surface for high‐temperature solar‐selective absorber
Authors: Wang Jian , Chen Zijun , Li Dejie 
Published: April 2010

AbstractA two‐dimensional (2D) Mo photonic crystal (PhC) surface is proposed for high‐temperature solar‐selective absorber. The influence of PhC structural parameters on the reflectance between 0.3 and 12 µm is studied by the rigorous coupled‐wave analysis (RCWA) method. Simulation results show that such a surface with submicrometer periodicity exhibits high solar absorbance α together with low thermal emittance ε, while the former can be improved by grading profile and high aspect ratio. Optimized microcone Mo PhC surface exhibits a normal solar absorbance αn = 0.919 and a hemispherical thermal emittance εh = 0.149 at 1000 °C, showing its promising potential for high‐temperature solar‐selective absorbers. magnified image
The structure and reflectance of 2D Mo PhC surface.
Arbitrarily shaped Si nanostructures by glancing angle ion beam sputter deposition
Authors: Patzig Christian , Miessler André , Karabacak Tansel , Rauschenbach Bernd 
Published: April 2010

AbstractUsing glancing angle deposition by ion beam sputtering, sculptured thin films (STFs) consisting of various Si nanostructures of manyfold shapes, such as inclined and vertical columns, screws, and spirals, were deposited on Si substrates. It will be shown that morphology, shape, and diameter of the structures are influenced and can thus be controlled by adjusting various deposition parameters, including substrate temperature and ratio of substrate rotational speed to film deposition rate. Especially the temperature‐controlled surface diffusion is found to play an important role in the growth of STFs. magnified image
Cross‐sectional scanning electron microscopy micrograph of helical Si nanostructures, deposited with ion beam sputter glancing angle deposition.
Bias polarity dependent local electrical conduction in resistive switching TiO2 thin films
Authors: Shin Yong Cheol , Lee Min Hwan , Kim Kyung Min , Kim Gun Hwan , Song Seul Ji , Seok Jun Yeong , Hwang Cheol Seong 
Published: April 2010

AbstractThe localized electrical conduction behaviour of a resistive switching TiO2 film was examined by conductive atomic force microscopy (CAFM). Localized filamentary electrical conduction was well resolved with a negative tip bias with respect to the Pt bottom electrode whereas almost uniform electrical conduction was observed with a positive bias. The bias dependence of the CAFM result was attributed to local electrochemical reactions mediated by the high electric field near the CAFM tip. A positive tip bias extended the electrically conducting area much more than the actual tip–surface contact area presumably due to facilitated oxygen loss by the high electric field. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Type I error rate control in adaptive designs for confirmatory clinical trials with treatment selection at interim
Authors: Posch Martin , Maurer Willi , Bretz Frank 
Published: April 2010

AbstractInterest in confirmatory adaptive combined phase II/III studies with treatment selection has increased in the past few years. These studies start comparing several treatments with a control. One (or more) treatment(s) is then selected after the first stage based on the available information at an interim analysis, including interim data from the ongoing trial, external information and expert knowledge. Recruitment continues, but now only for the selected treatment(s) and the control, possibly in combination with a sample size reassessment. The final analysis of the selected treatment(s) includes the patients from both stages and is performed such that the overall Type I error rate is strictly controlled, thus providing confirmatory evidence of efficacy at the final analysis. In this paper we describe two approaches to control the Type I error rate in adaptive designs with sample size reassessment and/or treatment selection. The first method adjusts the critical value using a simulation‐based approach, which incorporates the number of patients at an interim analysis, the true response rates, the treatment selection rule, etc. We discuss the underlying assumptions of simulation‐based procedures and give several examples where the Type I error rate is not controlled if some of the assumptions are violated. The second method is an adaptive Bonferroni–Holm test procedure based on conditional error rates of the individual treatment–control comparisons. We show that this procedure controls the Type I error rate, even if a deviation from a pre‐planned adaptation rule or the time point of such a decision is necessary. Copyright © 2010 John Wiley & Sons, Ltd.
Contribution of atmospheric nitrate to stream‐water nitrate in Japanese coniferous forests revealed by the oxygen isotope ratio of nitrate
Authors: Tobari Y. , Koba K. , Fukushima K. , Tokuchi N. , Ohte N. , Tateno R. , Toyoda S. , Yoshioka T. , Yoshida N. 
Published: April 2010

AbstractEvaluation of the openness of the nitrogen (N) cycle in forest ecosystems is important in efforts to improve forest management because the N supply often limits primary production. The use of the oxygen isotope ratio (δ18O) of nitrate is a promising approach to determine how effectively atmospheric nitrate can be retained in a forest ecosystem. We investigated the δ18O of nitrate in stream water in order to estimate the contribution of atmospheric NO in stream‐water NO (fatm) from 26 watersheds with different stand ages (1–87 years) in Japan. The stream‐water nitrate concentrations were high in young forests whereas, in contrast, old forests discharged low‐nitrate stream water. These results implied a low fatm and a closed N cycle in older forests. However, the δ18O values of nitrate in stream water revealed that fatm values were higher in older forests than in younger forests. These results indicated that even in old forests, where the discharged N loss was small, atmospheric nitrate was not retained effectively. The steep slopes of the studied watersheds (>40°) which hinder the capturing of atmospheric nitrate by plants and microbes might be responsible for the inefficient utilization of atmospheric nitrate. Moreover, the unprocessed fraction of atmospheric nitrate in the stream‐water nitrate in the forest (funprocessed) was high in the young forest (78%), although funprocessed was stable and low for other forests (5–13%). This high funprocessed of the young forest indicated that the young forest retained neither atmospheric NO nor soil NO effectively, engendering high stream‐water NO concentrations. Copyright © 2010 John Wiley & Sons, Ltd.
Determination of absolute photoionization cross‐sections of alkanes and cyclo‐alkanes
Authors: Zhou Zhongyue , Zhang Lidong , Xie Mingfeng , Wang Zhandong , Chen Dongna , Qi Fei 
Published: April 2010

AbstractAbsolute photoionization and dissociative photoionization cross‐sections of eleven n‐alkanes (n‐pentane, n‐hexane, n‐heptane, n‐nonane, n‐decane, n‐undecane, n‐dodecane, n‐tridecane, n‐tetradecane, n‐pentadecane and n‐hexadecane), three cyclo‐alkanes (cyclopentane, methylcyclohexane and trans‐decahydronaphthalene) and iso‐octane were measured for photon energies from the ionization thresholds to 11.5 eV. The measurements were performed with the binary‐liquid‐mixture method utilizing the photoionization cross‐sections of benzene as a calibration standard. The ionization energies of n‐alkanes and cyclo‐alkanes were also calculated at the B3P86/6‐31 + +G(d,p) level and by the G3B3 method. Copyright © 2010 John Wiley & Sons, Ltd.
A Bayesian model averaging approach with non‐informative priors for cost‐effectiveness analyses
Authors: Conigliani Caterina 
Published: April 2010

AbstractWe consider the problem of assessing new and existing technologies for their cost‐effectiveness in the case where data on both costs and effects are available from a clinical trial, and we address it by means of the cost‐effectiveness acceptability curve. The main difficulty in these analyses is that cost data usually exhibit highly skew and heavy‐tailed distributions, so that it can be extremely difficult to produce realistic probabilistic models for the underlying population distribution. Here, in order to integrate the uncertainty about the model into the analysis of cost data and into cost‐effectiveness analyses, we consider an approach based on Bayesian model averaging (BMA) in the particular case of weak prior informations about the unknown parameters of the different models involved in the procedure. The main consequence of this assumption is that the marginal densities required by BMA are undetermined. However, in accordance with the theory of partial Bayes factors and in particular of fractional Bayes factors, we suggest replacing each marginal density with a ratio of integrals that can be efficiently computed via path sampling. Copyright © 2010 John Wiley & Sons, Ltd.
Pattern‐mixture models for analyzing normal outcome data with proxy respondents
Authors: Shardell Michelle , Hicks Gregory E. , Miller Ram R. , Langenberg Patricia , Magaziner Jay 
Published: April 2010

AbstractStudies of older adults often involve interview questions regarding subjective constructs such as perceived disability. In some studies, when subjects are unable (e.g. due to cognitive impairment) or unwilling to respond to these questions, proxies (e.g. relatives or other care givers) are recruited to provide responses in place of the subject. Proxies are usually not approached to respond on behalf of subjects who respond for themselves; thus, for each subject, data from only one of the subject or proxy are available. Typically, proxy responses are simply substituted for missing subject responses, and standard complete‐data analyses are performed. However, this approach may introduce measurement error and produce biased parameter estimates. In this paper, we propose using pattern‐mixture models that relate non‐identifiable parameters to identifiable parameters to analyze data with proxy respondents. We posit three interpretable pattern‐mixture restrictions to be used with proxy data, and we propose estimation procedures using maximum likelihood and multiple imputation. The methods are applied to a cohort of elderly hip‐fracture patients. Copyright © 2010 John Wiley & Sons, Ltd.
A flexible unified approach to the analysis of pre‐clinical combination studies
Authors: Harbron Chris 
Published: April 2010

AbstractCombinations of drugs are increasingly being used in a variety of diseases. Pre‐clinical experiments allow the responses of many drug compounds to be studied in combination with the goal of identifying compounds acting synergistically. This paper presents a unified approach to analysing data from combination studies, calculating a hierarchy of interaction indices to powerfully and flexibly describe the synergistic profile of the combination space studied, utilizing standard statistical software to generate estimates of confidence and provide statistical tests. The approach can work with a wide variety of experimental designs and response patterns and will deal with partial responses and inactive compounds. As well as identifying synergy or antagonism, the same approach can also be used to identify a benefit or detriment to monotherapy. The approach is illustrated with data from anin vitrostudy. Copyright © 2010 John Wiley & Sons, Ltd.
Microbial Synthesis of Multishaped Gold Nanostructures
Authors: Das Sujoy K. , Das Akhil R. , Guha Arun K. 
Published: April 2010

AbstractThe development of methodologies for the synthesis of nanoparticles of well‐defined size and shape is a challenging one and constitutes an important area of research in nanotechnology. This Full Paper describes the controlled synthesis of multishaped gold nanoparticles at room temperature utilizing a simple, green chemical method by the interaction of chloroauric acid (HAuCl4 · 3H20) and cell‐free extract of the fungal strain Rhizopus oryzae. The cell‐free extract functions as a reducing, shape‐directing, as well as stabilizing, agent. Different shapes of gold nanocrystals, for example, triangular, hexagonal, pentagonal, spherical, spheroidal, urchinlike, two‐dimensional nanowires, and nanorods, are generated by manipulating key growth parameters, such as gold ion concentration, solution pH, and reaction time. The synthesized nanostructures are characterized by UV/Vis and Fourier‐transform infrared spectroscopy, transmission electron microscopy, and energy dispersive X‐ray analysis studies. Electron diffraction patterns reveal the crystalline nature of the nanoparticles and a probable mechanism is proposed for the formation of the different structural entities.
Modeling on Dendrite Growth of Medium Carbon Steel during Continuous Casting
Authors: Guo W. , Zhang L. , Zhu M. 
Published: April 2010

AbstractDendrite growth is an important phenomenon during steel solidification. In the current paper, a numerical method was used to analyse and calculate the dendrite tip radius, dendrite growth velocity, liquid concentration, temperature gradient, cooling rate, secondary dendrite arm spacing, and the dendrite tip temperature in front of the solid/liquid (S/L) interface for the solidification process of medium carbon steels during continuous casting. The current model was well validated by published models and measurement data. The results show that in the continuous casting process, the dendrite growth rate is dominated by the casting speed. Dendrite growth rate, liquid concentration at the S/L interface, temperature gradient and cooling rate decrease with proceeding solidification and solid shell thickness growth, while other parameters such as dendrite tip radius, secondary dendrite arm spacing, and dendrite tip temperature in front of the S/L interface become larger with solidification progress and solid shell thickness growth. Parametric investigations were carried out. The effects of the stability coefficient, temperature gradient and casting speed on the micro‐structural parameters were discussed. Under the same conditions, higher casting speed promotes coarser secondary dendrite arm spacing and enlarges the dendrite tip radius, while decreasing temperature gradient, reducing the dendrite growth rate and making the solute distribute more uniform.