bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlation of free radical copolymerization behavior and copolymer properties with the strength of π‐π stacking interactions between aromatic fluorocarbons and aromatic hydrocarbons: Comparison of the copolymerization behavior of 2,3,4,5,6‐pentafluorostyrene with styrene, 1‐vinylnaphthalene and 2‐vinylnaphthalene
Authors: Pugh Coleen , Paz‐Pazos Marta , Tang Chau N. 
Published: December 2008

Abstract2,3,4,5,6‐Pentafluorostyrene (PFS) was copolymerized with 1‐vinylnaphathalene (1VN) in bulk by radical copolymerization at 25 °C (r1VNrPFS = 0.070) using t‐butylperoxy pivalate as the inititator, at 70 °C (r1VNrPFS = 0.11) using benzyol peroxide as the initiator, and at 120 °C (r1VNrPFS = 0.28) using t‐butyl peroxide as the initiator; PFS was also copolymerized with 2‐vinylnaphathalene (2VN) in bulk by radical copolymerization at 70 °C (r2VNrPFS = 0.15) under similar conditions. Their reactivity ratios were determined at low monomer conversions using the nonlinear least‐squares method of analysis, which demonstrated that both comonomer pairs tend to alternate, and that their alternating tendency increases with decreasing temperature, similar to the radical copolymerizations of PFS with styrene (St) in bulk. The glass transition temperatures determined by differential scanning calorimetry are elevated relative to their mole‐average values, with the extent of elevation being greater for the 1VN‐PFS copolymers than for the 2VN‐PFS copolymers, which is greater than that for St‐PFS copolymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 331–345, 2009
Imino‐indolate half‐titanocene chlorides: Synthesis and their ethylene (co‐)polymerization
Authors: Zuo Weiwei , Zhang Min , Sun Wen‐Hua 
Published: December 2008

AbstractA series of imino‐indolate half‐titanocene chlorides, Cp′Ti(L)Cl2 (C1–C7: Cp′ = C5H5, MeC5H4, C5Me5, L = imino‐indolate ligand), were synthesized by the reaction of Cp′TiCl3 with sodium imino‐indolates. All complexes were characterized by elemental analysis, 1H and 13C NMR spectroscopy. Moreover, the molecular structures of two representative complexes C4 and C6 were confirmed by single crystal X‐ray diffraction analysis. On activation with methylaluminoxane (MAO), these complexes showed good catalytic activities for ethylene polymerization (up to 7.68 × 106 g/mol(Ti)·h) and ethylene/1‐hexene copolymerization (up to 8.32 × 106 g/mol(Ti)·h), producing polyolefins with high molecular weights (for polyethylene up to 1808 kg/mol, and for poly(ethylen‐co‐1‐hexene) up to 3290 kg/mol). Half‐titanocenes containing ligands with alkyl substituents showed higher catalytic activities, whereas the half‐titanocenes bearing methyl substituents on the cyclopentadienyl groups showed lower productivities, but produced polymers with higher molecular weights. Moreover, the copolymerization of ethylene and methyl 10‐undecenoate was demonstrated using the C1/MAO catalytic system. The functionalized polyolefins obtained contained about 1 mol % of methyl 10‐undecenoate units and were fully characterized by several techniques such as FT‐IR, 1H NMR, 13C NMR, DSC, TGA and GPC analyses. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 357–372, 2009
Magnetic field effects on the copolymerization of water‐soluble and ionic monomers
Authors: Rintoul Ignacio , Wandrey Christine 
Published: December 2008

AbstractThe effect of magnetic field (MF) on the radical copolymerization of a series of water‐soluble and ionic monomers is presented including acrylamide (AM), acrylic acid (AA), its ionized form acrylate (A−), and diallyldimethylammonium chloride (DADMAC). The following combinations have been studied: AM/AA, AM/A−, AM/DADMAC, and AA/DADMAC. In addition to the MF, strong electrostatic interactions are present for the majority of monomer combinations and conditions. Although the monomer consumption rate (Rp) increased up to 65% applying a MF of 0.1 Tesla, the composition of the resulting copolymers was not affected under such conditions. Despite this increase of Rp by MF, the electrostatic repulsion between ionic monomers and charged growing radicals dominates Rp and governs the copolymer composition with and without MF. The order of the experimentally obtained reactivity ratios reflects the extent of electrostatic interaction: rAM/AA (1.41) < r (3.10) < rAA/DADMAC (4.25) < rAM/DADMAC (6.95) and rAA/AM (2.20) > rDADMAC/AA (0.25) > r (0.17) > rDADMAC/AM (0.03). Overall, weak MF offers to reduce the production time without modifying the product composition. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 373–383, 2009
Synthesis of well‐defined 7‐arm and 21‐arm poly(N‐isopropylacrylamide) star polymers with β‐cyclodextrin cores via click chemistry and their thermal phase transition behavior in aqueous solution
Authors: Xu Jian , Liu Shiyong 
Published: December 2008

AbstractThe syntheses of well‐defined 7‐arm and 21‐arm poly(N‐isopropylacrylamide) (PNIPAM) star polymers possessing β‐cyclodextrin (β‐CD) cores were achieved via the combination of atom transfer radical polymerization (ATRP) and click reactions. Heptakis(6‐deoxy‐6‐azido)‐β‐cyclodextrin and heptakis[2,3,6‐tri‐O‐(2‐azidopropionyl)]‐β‐cyclodextrin, β‐CD‐(N3)7 and β‐CD‐(N3)21, precursors were prepared and thoroughly characterized by nuclear magnetic resonance and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. A series of alkynyl terminally functionalized PNIPAM (alkyne‐PNIPAM) linear precursors with varying degrees of polymerization (DP) were synthesized via atom transfer radical polymerization (ATRP) of N‐isopropylacrylamide using propargyl 2‐chloropropionate as the initiator. The subsequent click reactions of alkyne‐PNIPAM with β‐CD‐(N3)7 and β‐CD‐(N3)21 led to the facile preparation of well‐defined 7‐arm and 21‐arm star polymers, namely β‐CD‐(PNIPAM)7 and β‐CD‐(PNIPAM)21. The thermal phase transition behavior of 7‐arm and 21‐arm star polymers with varying molecular weights were examined by temperature‐dependent turbidity and micro‐differential scanning calorimetry, and the results were compared to those of linear PNIPAM precursors. The anchoring of PNIPAM chain terminal to β‐CD cores and high local chain density for star polymers contributed to their considerably lower critical phase separation temperatures (Tc) and enthalpy changes during phase transition as compared with that of linear precursors. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 404–419, 2009
Immobilization of RAFT agents on silica nanoparticles utilizing an alternative functional group and subsequent surface‐initiated RAFT polymerization
Authors: Yang Yingkui , Yang Zhifang , Zhao Qiang , Cheng Xinjian , Tjong Sie Chin , Li Robert Kwok Yiu , Wang Xiaotao , Xie Xiaolin 
Published: December 2008

AbstractSilica–polystyrene core‐shell particles were successfully prepared by surface‐mediated reversible addition fragmentation chain transfer (RAFT) polymerization of styrene monomer from the surfaces of the silica‐supported RAFT agents. Initially, macro‐RAFT agents were synthesized by RAFT polymerization of γ‐methacryloxypropyltrimethoxysilane (MPS) in the presence of chain transfer agents (CTAs). Immobilization of CTAs onto the silica surfaces was then performed by reacting silica with macro‐RAFT agents via a silane coupling. Grafting of polymer onto silica forms core‐shell nanostructures and shows a sharp contrast between silica core and polymer shell in the phase composition. The thickness of grafted‐polymer shell and the diameter of core‐shell particles increase with the increasing ratio of monomer to silica. A control experiment was carried out by conventional free radical emulsion copolymerization of MPS‐grafted silica and styrene under comparable conditions. The resulting data provide further insight into the chemical composition of grafted‐polymers that are grown from the silica surface through RAFT process. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 467–484, 2009
Effect of POSS on crystalline transitions and physical properties of polyamide 12
Authors: Wan Chaoying , Zhao Feng , Bao Xujin , Kandasubramanian Bala , Duggan Matt 
Published: December 2008

AbstractPolyamide 12/Trisilanolphenyl‐POSS (PA 12/POSS) composites were prepared via melt‐compounding. The effect of polyhedral oligomeric silsesquioxane (POSS) on crystalline structure and crystalline transition of PA 12 was investigated by wide‐angle X‐ray diffraction (WAXD) and real time fourier transform infrared spectroscopy (FTIR). WAXD results indicated that PA 12 crystallized into γ‐form as slowly cooling from melt and the presence of POSS did not influence the crystalline structure of PA 12. Both PA 12 and PA 12/POSS composites underwent Brill transitions when they were heated from room temperature to melt point. Real time FTIR patterns showed that an absorption band at 697 cm−1 ascribed to Amide V (α) mode was emerged along with the disappearance of Amide VI (γ) band at 628 cm−1 with the increase of the temperature for PA 12 and PA 12/POSS composites, which suggested that the γ‐form crystalline has transformed into α form. The Brill bands were identified and the transformed mechanism was discussed based on the real FTIR results. The addition of POSS enhanced the tensile strength and thermal stability of PA 12. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 121–129, 2009
Relationship between fracture toughness and domain size of liquid‐crystalline epoxy resins having polydomain structure
Authors: Harada Miyuki , Sumitomo Kaori , Nishimoto Yuma , Ochi Mitsukazu 
Published: December 2008

AbstractA liquid‐crystalline (LC) epoxy resin was cured at different temperatures and some types of curing systems having different phase structures (isotropic or polydomain, which have a microscopically ordered LC network structure) were obtained. The diameters of each domain in the polydomain system changed from the small to the larger size. The diameters of the LC domains were evaluated using a polarized optical microscope and the polarized microscopy FTIR mapping method. These systems were used to investigate the relationship between the network arrangement and mechanical properties. The fracture toughness of the cured systems was related to the enlargement of the ordered area in the network structures. With the toughness improvement, the meandering cracks were observed at the fracture surfaces. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 156–165, 2009
Urine levels of catecholamines in Greek children with obstructive sleep‐disordered breathing
Authors: Kaditis Athanasios G. , Alexopoulos Emmanouel I. , Damani Eleni , Hatzi Fotini , Chaidas Konstantinos , Kostopoulou Thomais , Tzigeroglou Arhontia , Gourgoulianis Konstantinos 
Published: December 2008

AbstractIntroductionAdults with obstructive sleep apnea have increased sympathetic activity. It was hypothesized that in children with symptoms of obstructive sleep‐disordered breathing (SDB), morning urine levels of catecholamines correlate with severity of nocturnal hypoxemia.MethodsChildren with snoring referred for polysomnography and controls without snoring were recruited. Morning urine norepinephrine, epinephrine, normetanephrine, and metanephrine levels were measured (ng/mg urine creatinine).ResultsTwelve children (age 5.2 ± 2.3 years) with severe hypoxemia (oxygen saturation of hemoglobin‐SpO2nadir ≤86%), 20 subjects (age 6.1 ± 2.1 years) with moderate hypoxemia (SpO2nadir ≤90% and >86%), 22 children (age 6.6 ± 1.5 years) with mild nocturnal hypoxemia (SpO2nadir >90%), and 10 controls (age 7.1 ± 2.8 years) were studied. Children with severe hypoxemia had significantly higher log‐transformed norepinephrine levels (1.63 ± 0.29) compared to those with moderate hypoxemia (1.43 ± 0.22;P < 0.05) or compared to controls (1.39 ± 0.31;P < 0.05). In subjects with SDB, log‐transformed oxygen desaturation of hemoglobin index or SpO2nadir predicted log‐transformed norepinephrine levels after adjustment by age, gender and body mass index (r2 = 0.24; and r2 = 0.24, respectively;P < 0.01).ConclusionsSeverity of nocturnal hypoxemia in children with intermittent upper airway obstruction during sleep correlates with morning urine levels of norepinephrine suggesting increased sympathetic tone. Pediatr Pulmonol. 2009; 44:38–45. © 2008 Wiley‐Liss, Inc.
Associations of psychosocial factors with health outcomes among youth with cystic fibrosis
Authors: Patterson Joän M. , Wall Melanie , Berge Jerica , Milla Carlos 
Published: December 2008

AbstractPurposeThe purpose of this study was to examine the relationship of strains, resources, feelings, and behaviors about treatment adherence reported by youth with cystic fibrosis (CF) with repeated clinic measures of their pulmonary function and nutritional status.MethodsLinear mixed models, stratified by gender, adjusting for age, were used to examine the effects of strains, resources, and adherence behaviors on repeated pulmonary function and nutritional status measures. All 10–21 years old with CF at the Minnesota Cystic Fibrosis Center were invited by mail to participate. Of these 177 youth, 51% (43 boys, 47 girls) returned surveys. Forced expiratory volume in 1 sec and predicted weight‐for‐height were extracted from participants' clinic records for the 18 months following receipt of the survey.ResultsFemales showed significantly greater variability in repeated measures of pulmonary function and nutritional status compared to males. Parent–youth strains, physical strains, activity limitations, and cough suppression had significant effects on the 18‐month mean of pulmonary function measures for females, but only physical strains had a significant effect for males.ConclusionCompared to males, females experienced more strains and poorer treatment adherence, which may be factors associated with declines in pulmonary function observed among females with CF during the adolescent years. Pediatr Pulmonol. 2009; 44:46–53. © 2008 Wiley‐Liss, Inc.
Obstructive sleep apnea syndrome in an adolescent girl with hypertrophic lingual thyroid
Authors: Lin Wan‐Ni , Lee Li‐Ang , Wang Chih‐Ching , Li Hsueh‐Yu 
Published: December 2008

AbstractWe present a 14‐year‐old girl whose initial diagnosis was obstructive sleep apnea syndrome (OSAS) with symptoms of habitual snore, sleep breath holding, shortness of breath, and lump in throat. Lingual thyroid was diagnosed by thyroid scan and histology, and was treated by radioactive iodine therapy and endoscopic carbon dioxide laser therapy. Her OSAS completely subsided after lingual thyroid surgery. Physicians should be aware of rare causes of OSAS in children, such as lingual thyroid and certainly if accompanied by difficulties in swallowing and speech problems. Pediatr Pulmonol. 2009; 44:93–95. © 2008 Wiley‐Liss, Inc.
Neuropad: early diagnostic test for diabetic peripheral neuropathy
Authors: Malik Rayaz 
Published: December 2008

AbstractDiabetic foot syndrome is a significant cause of morbidity in patients with diabetes, and early diagnosis of peripheral neuropathy can improve prognosis. In this New product review Professor Malik describes Neuropad, a new prescribable diagnostic test for peripheral diabetic neuropathy. Copyright © 2008 Wiley Interface Ltd
Switching kinetics of a relaxor ferroelectric Sr0.75Ba0.25Nb2O6 observed by the second harmonic generation method
Authors: Volk Tatyana , Isakov Dmitry , Belsley Michael Scott , Ivleva Lyudmila 
Published: December 2008

AbstractIn this work we present a study of the ferroelectric switching kinetic process in strontium–barium niobate (SBN). The kinetics of polarization deduced from the dynamics of the diffuse second harmonic generation is in good qualitative agreement with thekinetics observed by more traditional polarization methods. Our work highlights the specific characteristics of polarization reversal in SBN, which is fundamentally different from that which occurs in model ferroelectrics. The presented optical measurements of the polarization processes provide several experimental advantages over traditional electrical measurements. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Utilization of high pressure for synthesizing superconducting semiconductors: analysis of Ekimov's method
Authors: Shirai Koun , Dekura Haruhiko , Yanase Akira 
Published: December 2008

AbstractUse of a high‐pressure process is proposed for synthesizing highly doped semiconductors. Working on a real example in a recent experiment by Ekimov on B‐doped diamond synthesis, a theoretical investigation has been made of an efficient doping method. The underlying principle is simple: stiffer materials are energetically favorable over softer ones under high pressure. Softer impurities are easily dissolved in stiff crystals. In Ekimov's method, the energy required for a B atom to transfer from boron carbide to diamond comes from the energy gain by converting graphite to diamond, in addition to the entropy effect of dissolving the B atom in diamond. On the basis of this analysis, a potential of more than 10 at% of doping, which would improve Tc, by high‐pressure processes is suggested. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Measurement of phonon pressure coefficients for a precise determination of deformation potentials in SiGe alloys
Authors: Reparaz J. S. , Goñi A. R. , Bernardi A. , Alonso M. I. , Garriga M. 
Published: December 2008

AbstractFor an effective use of Raman scattering as strain characterization tool in SiGe nanostructures a precise knowledge of the phonon deformation potentials (DPs) is strictly necessary. The optical phonon DPs can be determined by means of Raman scattering measurements from the cleaved edge of a biaxially strained SiGe alloy layer grown pseudomorphically on silicon and subsequently capped. Due to uncertainties in the literature values of the unstrained phonon frequencies it turns out that the desired degree of accuracy is only attained by complementing the Raman measurements from the edge with that of the hydrostatic pressure coefficient of the optical phonons. For that purpose we have grown by molecular beam epitaxy up to seven partially strained Si1–x Gex alloys on Si spanning the entire compositional range and measured the dependence on hydrostatic pressure of the frequency of the Ge‐like, Si‐like and mixed Si–Ge optical modes. After correcting for the pressure dependent biaxial stress induced by the Si substrate on the alloy layer and taking into account the dependence on alloy composition of the bulk modulus we obtain a fairly constant value of the Grüneisen parameter around 1.0 for all three optical modes in the whole range of Ge contents. We also determined the strain shift coefficients for the three modes, which are essentially independent of Ge content between 0.4 and 1. Our results are in very good agreement with recentcalculations of the SiGe phonon deformation potentials using a modified Keating model, which settles the longstanding issue about the large discrepancies between results from different experiments. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic phases of magnetic polarons in diluted magnetic semiconductor nanocrystals
Authors: Cheng Shun‐Jen 
Published: December 2008

AbstractWe present theoretical studies of magnetism in II‐VI magnetic nanocrystals (NCs) containing single electron coupled to substitutional magnetic ions Mn2+. By using exact diagonalization techniques, we explore the magnetic phases of magnetic polarons in NCs doped with few Mn2+ ions, as functions of NC size, Mn number and positions. We show that ferromagnetic magnetic polarons (MPs) are stably formed in small magnetic NCs due to strong quantum confinement. By contrast, magnetic polarons with short ranged Mn‐clusters in larger NCs exhibit various distinct magnetic phases, from ferromagnetism (FM) to antiferromagnetism (AF), sensitively depending on NC size. The stability of magnetic polarons in NCs with arbitrary number of Mn ions are analyzed within a proposed solvable model, supported by the numerical results calculated by using local mean field theory (MFT). (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Light‐driven rotary molecular motors: an ultrafast optical study
Authors: Augulis Ramūnas , Klok Martin , Feringa Ben L. , Loosdrecht Paul H. M. van 
Published: December 2008

AbstractThe cover picture of this issue of Phys. Status Solidi C has been taken from the article [1]. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hot spots in multicrystalline silicon solar cells: avalanche breakdown due to etch pits
Authors: Bauer J. , Wagner J.‐M. , Lotnyk A. , Blumtritt H. , Lim B. , Schmidt J. , Breitenstein O. 
Published: December 2008

AbstractMulticrystalline silicon solar cells typically show hard breakdown beginning from about –13 V bias, which leads to the well‐known hot‐spot problem. Using special lock‐in thermography techniques, hard breakdown has been found to occur in regions of avalanche multiplication. A systematic study of these regions by various electron microscopy techniques has shown that the avalanche breakdown occurs at cone‐shaped holes, located at dislocations and caused by acidic texture etch. At their bottom, these etch pits lead to a strongly curved p–n junction exhibiting an electrostatic tip effect which quantitatively explains the field enhancement needed for enabling avalanche breakdown. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study on dynamics of surface structure by rapid and time‐resolved X‐ray photoelectron diffraction
Authors: Kisaka Y. , Hashimoto A. , Suzuki A. , Miyasaka S. , Nojima M. , Owari M. , Nihei Y. 
Published: December 2008

AbstractIt took several hours to obtain one X‐ray photoelectron diffraction (XPED) pattern because XPED measurement requires repeated acquisition of XPS as a function of emission angle. The measurement time using our previous XPED system was too long to clarify the dynamics of epitaxial growth and catalytic reaction. In the present study, in order to minimize the measurement time, we improved the software used to control the XPED system. Then, by using the improved system, we obtained information on the structural changes during the heating process of an ion‐bombarded silicon surface. Copyright © 2008 John Wiley & Sons, Ltd.
Dopamine D2Highreceptors measured ex vivo are elevated in amphetamine‐sensitized animals
Authors: Seeman Philip 
Published: December 2008

AbstractAlthough dopamine supersensitivity is a fundamental aspect of diseases such as schizophrenia and Parkinson's disease, the molecular basis of dopamine supersensitivity is not known. Because behavioral dopamine supersensitivity is associated with a marked elevation of striatal dopamine D2Highreceptors in vitro, it is important to develop methods to measure D2Highreceptors in vivo. The presentex vivostudy found that the dopamine agonist NPA ([‐]‐N‐propyl‐norapomorphine) inhibited the binding of the agonist [3H](+)PHNO to rat striatal D2 receptors significantly more than the D2 antagonist [3H]raclopride, when NPA was coinjected i.v. with each radioligand. These results suggest that the greater sensitivity of [3H](+)PHNO to inhibition by the coinjected NPA reflects in vivo competition at D2Highreceptors. Using rats that had been sensitized to amphetamine, thisex vivomethod found that the specific binding of [3H](+)PHNO that was displaced by 10 μg/kg of NPA was 2.4‐fold higher than that for control rats. These data agree with in vitro data showing a marked increase in D2Highsites after amphetamine sensitization. Therefore, it is recommended that this method of coinjecting the D2 radioligand and the dopamine agonist displacer be used in human positron tomography to detect D2Highreceptors in health and disease. Synapse 63:186–192, 2009. © 2008 Wiley‐Liss, Inc.