bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bis(β‐ketoamino)copper(II)/methylaluminoxane systems for homo‐ and copolymerizations of methyl acrylate and 1‐hexene
Authors: Gao Haiyang , Liu Xiaofang , Pei Lixia , Wu Qing 
Published: January 2010

AbstractTwo bis(β‐ketoamino)copper [ArNC(CH3)CHC(CH3)O]2Cu (1, Ar = 2,6‐dimethylphenyl; 2, Ar = 2,6‐diisopropylphenyl) complexes were synthesized and characterized. Homo‐ and copolymerizations of methyl acrylate (MA) and 1‐hexene with bis(β‐ketoamino)copper(II) complexes activated with methylaluminoxane (MAO) were investigated in detail. MA was polymerized in high conversion (>72%) to produce the syndio‐rich atactic poly(methyl acrylate), but 1‐hexene was not polymerized with copper complexes/MAO. Copolymerizations of MA and 1‐hexene with 1,2/MAO produced acrylate‐enriched copolymers (MA > 80%) with isolated hexenes in the backbone. The calculation of reactivity ratios showed that r(MA) is 8.47 and r(hexene) is near to 0 determined by a Fineman‐Ross method. The polymerization mechanism was discussed, and an insertion‐triggered radical mechanism was also proposed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1113–1121, 2010
Vanadium(V) complexes containing tetradentate amine trihydroxy ligands as catalysts for copolymerization of cyclic olefins
Authors: Wu Ji‐Qian , Mu Jing‐Shan , Zhang Sen‐Wang , Li Yue‐Sheng 
Published: January 2010

AbstractA series of vanadium(V) complexes bearing tetradentate amine trihydroxy ligands [NOOO], which differ in the steric and electronic properties, have been synthesized and characterized. Single crystal X‐ray analysis showed that these complexes are five or six coordinated around the vanadium center in the solid state. Their coordination geometries are octahedral or trigonal bipyramidal. In the presence of Et2AlCl, these complexes have been investigated as the efficient catalysts for ethylene polymerization and ethylene/norbornene copolymerization at elevated reaction temperature and produced the polymers with unimodal molecular weight distributions (MWDs), indicating the single site behaviors of these catalysts. Both the steric hindrance and electronic effect of the groups on the tetradentate ligands directly influenced catalytic activity and the molecular weights of the resultant (co)polymers. Other reaction parameters that influenced the polymerization behavior, such as reaction temperature, ethylene pressure, and comonomer concentration, are also examined in detail. Furthermore, high catalytic activities of up to 3.30 kg polymer/mmolV·h were also observed when these complexes were applied to catalyze the copolymerization of ethylene and 5‐norbornene‐2‐methanol, producing the high‐molecular‐weight copolymers (Mw = 157–400 kg/mol) with unimodal MWDs (Mw/Mn = 2.5–3.0) and high polar comonomer incorporations (up to 12.3 mol %). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1122–1132, 2010
Thermodynamic characteristics of poly(cyclohexylethylene‐b‐ethylene‐co‐ethylethylene) block copolymers
Authors: Mansour Ameara S. , Johnson Leah F. , Lodge Timothy P. , Bates Frank S. 
Published: January 2010

AbstractA series of poly(cyclohexylethylene‐b‐ethylene‐co‐ethylethylene) (C‐E/EE) diblock copolymers containing approximately 50% by volume glassy C blocks and varying fraction (x) of EE repeat units, 0.07 ≤ x ≤ 0.90, was synthesized by anionic polymerization and catalytic hydrogenation. The effects of ethyl branch content on the melt state segment–segment (χ) interaction parameter and soft (E/EE) block crystallinity were studied. The percent crystallinity ranged from approximately 30% at x = 0.07 to 0% at about x ≥ 0.30, while the melting temperature changed from 101 °C at x = 0.07 to 44 °C at x = 0.28. Dynamic mechanical spectroscopy was employed to determine the order–disorder transition (ODT) temperatures, from which χ was calculated assuming the mean‐field prediction (χNn)ODT = 10.5. Previously published results for the temperature dependent binary interaction parameters for C‐E (x = 0.07), C‐EE (x = 0.90), and E‐EE (x = 0.07 and x = 0.90) fail to account for the quantitative x dependence of χ, based on a simple binary interaction model. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 566–574, 2010
Controlled crystallization of poly(vinylidene fluoride) chains from mixed solvents composed of its good solvent and nonsolvent
Authors: Zhao Xuejuan , Cheng Jing , Chen Shuangjun , Zhang Jun , Wang Xiaolin 
Published: January 2010

AbstractPoly(vinylidene fluoride) (PVDF) chains with the same expanded state were obtained by dissolving PVDF resin in good solvent. Then, the crystallization of PVDF chains from mixed solvents composed of its good solvent and nonsolvent was investigated. N,N‐dimethylformamide (DMF) and ethanol were used as good solvent and nonsolvent of PVDF, respectively. The crystalline phases of PVDF were characterized by Fourier transform infrared (FTIR) spectroscopy and wide angle X‐ray diffraction (WAXD). For the crystallization of PVDF chains from mixed solvents, low ethanol content favored the formation of β phase, while high ethanol content resulted predominantly in the α phase. Different crystallization morphology was observed from the scanning electron microscopy (SEM) images. The obvious spherulite morphology disappeared with the increase in ethanol content in mixed solvent. According to thermal analyses, the crystallized PVDF from mixed solvents with high ethanol content had lower onset melting temperatures than that from low ethanol content. Smaller lamellar thickness calculated from WAXD data reasoned the low onset melting temperatures. The above results indicated that the crystallization of PVDF chains from mixed solvent was a “controlled” process by ethanol content. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 575–581, 2010
A New Method for Evaluating the Energy Characteristics of CHNO Energetic Compounds
Authors: Li Jinshan 
Published: January 2010

AbstractFrom the law of conversation of energy, the release energy from the initiation to the Chapman–Jouguet point during the detonation of an energetic compound has been deduced as a function of initial density, detonation velocity, and detonation pressure. For CHNO energetic compounds the relative release energy per unit volume (Iv) approaches the relative specific wall kinetic energy (Ecyl/EHMX) at 19 mm wall displacement from the cylinder test with HMX as reference. A good linear relationship between Iv and Ecyl/EHMX has been regressed, implying that Ecyl/EHMX is also a function of initial density, detonation velocity, and detonation pressure. It has been concluded that Iv can reflect the driving force of detonation products of energetic compounds and is appropriate to be used for the evaluation of energy characteristics. The assessment of the energy for a series of synthesized and theoretically designed high‐energy compounds reveals that the future of CHNO energetic compounds is promising after CL‐20 and ONC.
A Bayesian predictive strategy for an adaptive two‐stage design in phase II clinical trials
Authors: Sambucini Valeria 
Published: January 2010

AbstractPhase II clinical trials are typically designed as two‐stage studies, in order to ensure early termination of the trial if the interim results show that the treatment is ineffective. Most of two‐stage designs, developed under both a frequentist and a Bayesian framework, select the second stage sample size before observing the first stage data. This may cause some paradoxical situations during the practical carrying out of the trial. To avoid these potential problems, we suggest a Bayesian predictive strategy to derive an adaptive two‐stage design, where the second stage sample size is not selected in advance, but depends on the first stage result. The criterion we propose is based on a modification of a Bayesian predictive design recently presented in the literature (see (Statist. Med. 2008; 27:1199–1224)). The distinction between analysis and design priors is essential for the practical implementation of the procedure: some guidelines for choosing these prior distributions are discussed and their impact on the required sample size is examined. Copyright © 2010 John Wiley & Sons, Ltd.
Low‐ and High‐temperature Processes and Mechanisms in the Preparation of Porous Ceramics via Starch Consolidation Casting
Authors: Živcová Zuzana , Gregorová Eva , Pabst Willi 
Published: January 2010

AbstractStarch consolidation casting (SCC) is a versatile and well established process for shaping ceramic green bodies by casting starch‐containing suspensions into impermeable molds. The process is based on the ability of starch to swell and absorb water from aqueous ceramic suspensions after heating to approx. 80°C. The swelling factor is highest for potato starch (3.7) and significantly lower for the other starch types (down to approx. 2). A simple mathematical model is presented that allows the minimum consolidation time to be estimated on the basis of the swelling kinetics of starch granules as measured via laser diffraction. The critical temperature range for starch burnout before sintering the ceramic is 300–500°C, as determined by thermal analysis (thermogravimetry and differential thermal analysis). In this temperature range gaseous products may ignite, leading to strongly exothermic thermal effects. If the bodies are large and the starch content high this may lead to defects in the (still unsintered) ceramic green bodies. Therefore this temperature range has to be carefully controlled in the production of ceramics prepared by SCC. The residual pores (remaining after starch burnout) are too large to be closed during the firing step (insufficient driving force for sintering due to too low surface curvature). Therefore they do not contribute to shrinkage, and shrinkage is determined by the ceramic matrix alone. Porosities higher than 50% (corresponding to the maximum nominal starch content) may be obtained by combining SCC with partial sintering (resulting in porosities up to 70%).
Response Surface Methodology for the Optimization and Characterization of Cassava Starch‐graft‐Poly(acrylamide)
Authors: Jyothi Alummoottil N. , Sreekumar Janardhanan , Moorthy Subramoney N. , Sajeev Moothandaserry S. 
Published: January 2010

AbstractResponse surface methodology (RSM) was employed for the synthesis of cassava starch‐graft‐poly(acrylamide) using ceric ammonium nitrate as free radical initiator. Concentration of acrylamide, concentration of ceric ammonium nitrate, reaction temperature and duration of reaction were optimized using a 4‐factor 3‐level Box‐Behnken design. The dependent variables were percentage grafting (%G) and grafting efficiency (GE). Second order polynomial relationships were obtained for %G and GE, which explained the main, quadratic and interaction effects of factors. The highest%G and GE obtained were 174.8% and 90.7%, respectively. The optimum values of parameters predicted through RSM were 20 g acrylamide/10 g dry starch, 3.3 g/L ceric ammonium nitrate, 180 min reaction duration and 45ºC temperature with a %G of 190.0. For GE, the predicted levels of factors for the optimum value of 90.8% were 17.5 g acrylamide/10 g dry starch, 4.1 g/L ceric ammonium nitrate, 180 min reaction duration and 55ºC temperature. The graft reaction was confirmed by FTIR analysis, where the absorption bands corresponding to the C=O stretching and N‐H bending of the –CONH2 group were observed. Scanning electron microscopic studies on grafted starches revealed that the granular structure of the starch was affected by the reaction. X‐ray diffraction analysis showed that the crystallinity of starch was decreased as a result of grafting and the reduction was higher for the grafted starches with higher percentage grafting.
Hydrothermal Modifications of Tropical Tuber Starches. 1. Effect of Heat‐Moisture Treatment on the Physicochemical, Rheological and Gelatinization Characteristics
Authors: Jyothi Alummoottil N. , Sajeev Moothandaserry S. , Sreekumar Janardanan N. 
Published: January 2010

AbstractCassava, sweet potato and arrowroot starches have been subjected to heat‐moisture treatment (HMT) under different conditions using a response surface design of the variables. A comparative study was performed on the pasting properties, swelling behaviour and the gelatinization properties of the modified starches and also on the rheological and textural properties of their pastes. X‐ray diffraction studies have shown that cassava starch exhibited a slight decrease in crystallinity, whereas sweet potato and arrowroot starches showed an increase in crystallinity after HMT at 120ºC for 14 h with 20% moisture. The swelling volume was reduced and the solubility was enhanced for all three starches after HMT, but both effects were more pronounced in the case of arrowroot starch. The decrease in paste clarity of the starch after HMT was higher in the case of cassava and sweet potato starches. Viscosity studies showed that the peak viscosity of all three starches decreased after HMT, but the paste stability increased as seen from the reduced breakdown ratio and setback viscosity. Studies on rheological properties have shown that storage and loss moduli were higher for the starches heat‐moisture treated at higher moisture and lower temperature levels than the corresponding native starches. Storage of the gel at ‐20ºC resulted in a significant increase in storage modulus for all the three starches. All the textural parameters of the gels were altered after the treatment which depended on the nature of the starch and also the treatment condition.
Physicochemical Properties of Waxy and Normal Maize Starches Irradiated at Various pH and Salt Concentrations
Authors: Baik Byung‐Ryol , Yu Jin‐Young , Yoon Hyun‐Seong , Lee Ju‐Woon , Byun Myung‐Woo , Baik Byung‐Kee , Lim Seung‐Taik 
Published: January 2010

AbstractWaxy and normal maize starches of various pH values and salt contents were prepared, irradiated with gamma rays (5–20 kGy) and their molecular structure, pasting viscosity and rheological properties determined. Average molar mass and size of both waxy and normal maize starches decreased considerably by irradiation from >338.0×106 to <39.4×106 g/mol and from >237.5 to <125.2 nm, respectively. Adjustments of pH had little influence on the average molar mass and size of irradiated starch, whereas incorporation of salt greatly reduced the molar mass and size of irradiated waxy and normal maize starches. As the pH increased from 4 to 8, the pasting viscosity of the irradiated starches decreased from 1032 to 279 mPa s in waxy and from 699 to 381 mPa s in normal starches. Pasting viscosity of both irradiated waxy and normal starch decreased from 689 to 358 mPa s and from 327 to 184 mPa s as the salt concentration increased from 1 to 5%. The G′ of gels, determined during cooling from 90 to 10°C or storage for 8 h, decreased in irradiated waxy and normal starches by pre‐conditioning at pH 8 and in irradiated waxy starches by pre‐conditioning at 5% NaCl. With 5% NaCl, G′ of irradiated normal maize starch during cooling increased up to the irradiation level of 10 kGy, and increased during storage for 8 h at all levels of irradiation. Incorporated salt prior to irradiation appears to induce incremental modifications in the molecular structure, rheological and retrogradation properties of starch by boosting the degradation of molecules.
Mouse Kidney Progenitor Cells Accelerate Renal Regeneration and Prolong Survival after Ischemic Injury
Authors: Lee Po-Tsang , Lin Hsi-Hui , Jiang Si-Tse , Lu Pei-Jung , Chou Kang-Ju , Fang Hua-Chang , Chiou Yuan-Yow , Tang Ming-Jer 
Published: January 2010

Abstract
Acute tubular necrosis is followed by regeneration of damaged renal tubular epithelial cells, and renal stem cells are supposed to contribute to this process. The purpose of our study is to test the hypothesis that renal stem cells isolated from adult mouse kidney accelerate renal regeneration via participation in the repair process. A unique population of cells exhibiting characteristics consistent with renal stem cells, mouse kidney progenitor cells (MKPC), was isolated from Myh9 targeted mutant mice. Features of these cells include (1) spindle-shaped morphology, (2) self-renewal of more than 100 passages without evidence of senescence, and (3) expression of Oct-4, Pax-2, Wnt-4, WT-1, vimentin, α-smooth muscle actin, CD29, and S100A4 but no SSEA-1, c-kit, or other markers of more differentiated cells. MKPC exhibit plasticity as demonstrated by the ability to differentiate into endothelial cells and osteoblasts in vitro and endothelial cells and tubular epithelial cells in vivo. The origin of the isolated MKPC was from the interstitium of medulla and papilla. Importantly, intrarenal injection of MKPC in mice with ischemic injury rescued renal damage, as manifested by decreases in peak serum urea nitrogen, the infarct zone, and the necrotic injury. Seven days after the injury, some MKPC formed vessels with red blood cells inside and some incorporated into renal tubules. In addition, MKPC treatment reduces the mortality in mice after ischemic injury. Our results indicate that MKPC represent a multipotent adult stem cell population, which may contribute to the renal repair and prolong survival after ischemic injury.
Views of inquiry: Mismatches between views of science education faculty and students of an alternative certification program
Authors: Demir Abdulkadir , Abell Sandra K. 
Published: January 2010

AbstractThe purpose of this phenomenographic study was to: (a) gain an understanding of the meaning of inquiry held by beginning science teachers and their instructors in an Alternative Teacher Certification Program (ATCP); and (b) compare science teachers' views of inquiry with what they learned in their ATCP. Participants were four beginning science teachers and two faculty members involved in teaching science methods courses in the ATCP. Semi‐structured interviews, classroom observations, field notes, and written materials were the data sources. The primary data sources for the study were six to15 hours of classroom observation of teaching and learning and approximately 8 hours of interviewing with each teacher. Interviews with each faculty member were also completed. These interviews required 60–75 minutes. A phenomenological data analysis approach [Uljens, M. (1996). On the philosophical foundation of phenomenography. In G. Dall'Alba & B. Hasselgren (Eds.), Reflections on Phenomenography—Toward a methodology? (pp. 105–130). Göteborg: Acta Universitatis Gothoburgensis] was used to complete qualitative analyses and categorical summaries of the data. The results showed that the teachers held rather incomplete views of inquiry‐based teaching [National Research Council. (2000). Inquiry and the national science education standards. Washington, DC: National Academy Press], and these views were highly discrepant with the views of teacher education faculty. Implication of the findings for science teacher education and future research on the development of inquiry‐based practices are discussed. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 47:716–741, 2010
Development of a short version of the Neck Pain and Disability Scale
Authors: Blozik Eva , Kochen Michael M. , Herrmann‐Lingen Christoph , Scherer Martin 
Published: January 2010

AbstractPrevious evaluations of the 20‐item Neck Pain and Disability Scale (NPAD) were indicative of excessive redundancy of the measure. The aim of this study was to develop a shortened version of the NPAD (sf‐NPAD) based on results of item‐to‐total‐score correlations and factor analysis as published by the developers of the original NPAD. Two items with the highest item‐to‐total score correlation were selected per factor subscale with the exception of one factor consisting of only one item. This resulted in the selection of 9 items for the sf‐NPAD. The sf‐NPAD was validated in a separate sample of 448 neck pain patients from 15 general practices in the area of Göttingen/Germany. Participants completed the 20‐item NPAD German version and gave additional sociodemographic and clinical information. Psychometric properties of the sf‐NPAD were evaluated using Cronbach's alpha, item‐to‐total‐score correlation, and unrestricted principal factor analysis. Construct validity was evaluated by Pearson's r with clinical characteristics. Discriminative validity was examined by comparing differences between subgroups stratified by psychosocial characteristics using t‐tests for mean scores. Cronbach's alpha of the sf‐NPAD was 0.88. Item‐to‐total‐scale correlations ranged between 0.628 and 0.815, and sf‐NPAD items homogeneously loaded on a single factor. Correlation analysis showed high correlations with criterion variables. The sf‐NPAD scores of patient subgroups were significantly different showing good discriminative validity. In conclusion, the sf‐NPAD demonstrated good validity and internal consistency in this general practice setting. The abbreviated version may facilitate applicability of the scale in clinical and research settings.
Drift wave driven zonal flows in electron–positron–ion plasmas
Authors: KALADZE T. D. , POKHOTELOV O. A. , SHAD M. 
Published: January 2010

AbstractThe generation of large-scale zonal flows by small-scale electrostatic drift waves in electron–positron–ion (EPI) plasma is considered. The generation mechanism is based on the parametric excitation of convective cells by finite amplitude drift waves. To describe this process, the Hasegawa–Mima equation generalized for the case of EPI plasma is used. Explicit expressions for the maximum growth rate as well as for the optimal spatial dimensions of the zonal flows are obtained. Dependence of the growth rate on the spectrum purity of the wave packet is also investigated. The relevant instability conditions are determined.
Dusty magnetohydrodynamics in star-forming regions
Authors: VAN LOO S. , FALLE S. A. E. G. , HARTQUIST T. W. , HAVNES O. , MORFILL G. E. 
Published: January 2010

AbstractStar formation occurs in dark molecular regions where the number density of hydrogen nuclei nH exceeds 104 cm−3 and the fractional ionization is 10−7 or less. Dust grains with sizes ranging up to tenths of microns and perhaps down to tens of nanometers contain just less than 1% of the mass. Recombination on grains is important for the removal of gas-phase ions, which are produced by cosmic rays penetrating the dark regions. Collisions of neutrals with charged grains contribute significantly to the coupling of the magnetic field to the neutral gas. Consequently, the dynamics of the grains must be included in the magnetohydrodynamic models of large-scale collapse, the evolution of waves and the structures of shocks important in star formation.
Cavity-hollow cathode-sputtering source for titanium films
Authors: SCHRITTWIESER R. , IONITA C. , MURAWSKI A. , MASZL C. , ASANDULESA M. , NASTUTA A. , RUSU G. , DOUAT C. , OLENICI S. B. , VOJVODIC I. , DOBROMIR M. , LUCA D. , JAKSCH S. , SCHEIER P. 
Published: January 2010

AbstractA cavity-hollow cathode was investigated as low-cost sputtering source for titanium. An argon discharge is produced inside a hollow cathode consisting of two specifically formed disks of titanium. An additional cavity further enhances the pendulum effect of the electrons. Measurements with small Langmuir probes yielded evidence for the formation of a space charge double layer above the cathode. The sputtered atoms form negatively charged clusters. After further acceleration by the double layer the clusters impinge on the substrates. Titanium thin films were produced on highly oriented pyrolytic graphite. The films were investigated by a scanning tunnel microscope and X-ray photoelectron spectroscopy.