bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and solution properties of a pH‐responsive cyclopolymer of zwitterionic ethyl 3‐(N,N‐diallylammonio)propanephosphonate
Authors: Ali Shaikh A. , Abu‐Thabit N. Y. , Al‐Muallem Hasan A. 
Published: October 2010

AbstractThe zwitterionic monomer, ethyl 3‐(N,N‐diallylammonio)propanephosphonate, was cyclopolymerized in aqueous solutions using t‐butylhydroperoxide or ammonium persulfate as initiators to afford a polyphosphonobetaine (PPB). The protonation of P(O)OEtO– and deprotonation of NH+ groups in PPB by HCl and NaOH, gave the corresponding cationic polyphosphononic acid (CPP) and anionic polyphosphonate (APP). The presence of two pH‐responsive functionalities in APP has led to establish the equilibria:
APP ⇌ PPB ⇌ CPP, the position of which very much dictates the viscosity behavior of its aqueous solution. The PPB demonstrated “antipolyelectrolyte” viscosity behavior; however, in contrast to many polycarbo‐ and polysulfo‐betaines, it was found to be soluble in salt‐free water as well as in salt‐added solutions. Basicity constant (K1) of the amine group in APP, as determined by potentiometric technique, were found to be “apparent,” and as such followed the modified Henderson‐Hasselbalch equation. The study demonstrated a correlation between the basicity constants and viscosity values. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Radical–radical coupling of polystyrene chains using AGET ATRC
Authors: Domingues Katelyn M. , Tillman Eric S. 
Published: October 2010

AbstractActivators generated by electron transfer (AGET) was integrated into atom transfer radical coupling (ATRC) systems to drastically reduce the amount of copper catalyst required to achieve dimerization of monohalogenated polystyrene (PStX) precursors. PStCl or PStBr, prepared by ATRP, were activated and coupled in ATRC systems with varying equivalents of the reducing agent tin(II) ethyl hexanoate (Sn(EH)2) with ligand‐bound copper(I) and/or copper(II) present. Effective coupling was only observed in PStBr systems, with total copper content in the reaction mixture able to be reduced into the range of 10–25% of what is typically reported in traditional ATRC reactions of PSt while maintaining coupling yields of >50%. Additional reducing agents, glucose and ascorbic acid, were also studied and were found to be even more effective in some AGET ATRC reactions compared with Sn(EH)2. Best results were achieved with ascorbic acid as the reducing agent (>80% coupled product) with total copper content 25% of what was used for a traditional ATRC. Using an activators regenerated by electron transfer ATRP–AGET ATRC sequence resulted in an overall reduction of total copper down to 0.1–0.25% for the overall reaction sequence (compared with a traditional ATRP–ATRC sequence). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Photoinitiation mechanism of free radical photopolymerization in the presence of cyclic acetals and related compounds
Authors: Xiao P. , Lalevée J. , Allonas X. , Fouassier J.P. , Ley C. , El‐Roz M. , Shi S. Q. , Nie J. 
Published: October 2010

AbstractThe behavior of six cyclic acetals and related compounds in the photoinitiation step of a radical photopolymerization was investigated. As shown by the photopolymerization kinetic data obtained from FTIR spectroscopy, most of them are efficient coinitiators in the presence of benzophenone (BP) with efficiencies close to a reference amine coinitiator (ethyl dimethylaminobenzoate, EDB). Laser flash photolysis and ESR spin trapping technique were used to study the photochemical mechanisms of the production of initiating radicals and explain the differences in reactivity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Pressure–volume–temperature behavior of two polycyanurate networks
Authors: Guo Jiaxi , Simon Sindee L. 
Published: October 2010

AbstractThe pressure–volume–temperature (PVT) behavior was studied for two polycyanurate networks having different crosslink densities using a pressurizable dilatometer. The samples were studied at temperatures ranging from 60 to 180 °C and at pressures up to 170 MPa to yield PVT data in both rubbery and glassy states. The Tait equation is found to well describe the isobaric temperature scan and isothermal pressure scan data. The thermal expansion coefficients, instantaneous bulk moduli, and thermal pressure coefficients are extracted from the data and their dependence on crosslink density is examined. The time‐dependent viscoelastic bulk modulus (K(t)) is also calculated in the vicinity of the α‐relaxation from previously published pressure relaxation experimental data, and the strength and shape of the dispersion are found to be independent of crosslink density. The limiting bulk moduli depend strongly on temperature with those of the more loosely crosslinked sample being lower at a given temperature and pressure, although at Tg(P), the limiting moduli of the more loosely crosslinked sample are slightly higher than those of the more highly crosslinked sample. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010
Microstructure and morphology of self‐assembling multiblock poly(ethylene‐1‐butene)‐n copolymers in solution studied by wide‐Q small‐angle neutron scattering and microscopy
Authors: Radulescu A. , Schwahn D. , Stellbrink J. , Monkenbusch M. , Fetters L. J. , Richter D. 
Published: October 2010

AbstractMultiblock ethylene‐1‐butene copolymers (PEB‐n) with graded ethylene content (where n is the number of ethyl branches per 100 backbone carbons) represent efficient cold filter plugging point (CFPP) depressants for crude oils and middle distillates. The aggregation behavior and the interaction with wax molecules of a tetrablock PEB‐2.6/PEB‐6.0/PEB‐10.9/PEB‐13.2 and triblock PEB‐6.5/PEB‐8.9/PEB‐10.1 copolymers in decane solutions were investigated over a wide temperature range by combining different small‐angle neutron scattering techniques and optical microscopy. The experimental results revealed in the decrease of temperature formation and evolution of multisized structural levels showing a hierarchical organization on the length scale from 1 nm up to 10 μm. One‐dimensional polymer aggregates arising as initial structures associate and branch that lead to the occurrence of complex macroaggregates with diffusive interfaces and sizes of several microns. The one‐dimensional copolymer structure shows longitudinal density modulation and micellar‐like substructures in neat polymer solutions. When wax is added, this structure becomes more homogeneous in decrease of temperature as a consequence of the cocrystallization of wax and copolymer. The wax crystallization in board‐like objects of much smaller size than required by the CFPP criterion of oil and refinery industry (filter mesh size of 45 μm) is templated and controlled by the assembling features of the crystalline–amorphous PEB‐n multiblock copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Solution structures of chicken parvalbumin 3 in the Ca2+‐free and Ca2+‐bound states
Authors: Henzl Michael T. , Tanner John J. , Tan Anmin 
Published: October 2010

AbstractBirds express two β‐parvalbumin isoforms, parvalbumin 3 and avian thymic hormone (ATH). Parvalbumin 3 from chicken (CPV3) is identical to rat β‐parvalbumin (β‐PV) at 75 of 108 residues. CPV3 displays intermediate Ca2+affinity—higher than that of rat β‐parvalbumin, but lower than that of ATH. As in rat β‐PV, the attenuation of affinity is associated primarily with the CD site (residues 41–70), rather than the EF site (residues 80–108). Structural data for rat α‐ and β‐parvalbumins suggest that divalent ion affinity is correlated with the similarity of the unliganded and Ca2+‐bound conformations. We herein present a comparison of the solution structures of Ca2+‐free and Ca2+‐bound CPV3. Although the structures are generally similar, the conformations of residues 47 to 50 differ markedly in the two protein forms. These residues are located in the C helix, proximal to the CD binding loop. In response to Ca2+removal, F47 experiences much greater solvent accessibility. The side‐chain of R48 assumes a position between the C and D helices, adjacent to R69. Significantly, I49 adopts an interior position in the unliganded protein that allows association with the side‐chain of L50. Concomitantly, the realignment of F66 and F70 facilitates their interaction with I49 and reduces their contact with residues in the N‐terminal AB domain. This reorganization of the hydrophobic core, although less profound, is nevertheless reminiscent of that observed in rat β‐PV. The results lend further support to the idea that Ca2+affinity correlates with the structural similarity of the apo‐ and bound parvalbumin conformations. Proteins 2011. © 2010 Wiley‐Liss, Inc.
Recognition of β–calcineurin by the domains of calmodulin: Thermodynamic and structural evidence for distinct roles
Authors: O'Donnell Susan E. , Yu Liping , Fowler C. Andrew , Shea Madeline A. 
Published: October 2010

AbstractCalcineurin (CaN, PP2B, PPP3), a heterodimeric Ca2+‐calmodulin‐dependent Ser/Thr phosphatase, regulates swimming in Paramecia, stress responses in yeast, and T‐cell activation and cardiac hypertrophy in humans. Calcium binding to CaNB (the regulatory subunit) triggers conformational change in CaNA (the catalytic subunit). Two isoforms of CaNA (α, β) are both abundant in brain and heart and activated by calcium‐saturated calmodulin (CaM). The individual contribution of each domain of CaM to regulation of calcineurin is not known. Hydrodynamic analyses of (Ca2+)4‐CaM1–148 bound to βCaNp, a peptide representing its CaM‐binding domain, indicated a 1:1 stoichiometry. βCaNp binding to CaM increased the affinity of calcium for the N‐ and C‐domains equally, thus preserving intrinsic domain differences, and the preference of calcium for sites III and IV. The equilibrium constants for individual calcium‐saturated CaM domains dissociating from βCaNp were ∼1 μM. A limiting Kd ≤ 1 nM was measured directly for full‐length CaM, while thermodynamic linkage analysis indicated that it was approximately 1 pM. βCaNp binding to 15N‐(Ca2+)4‐CaM1–148 monitored by 15N/1HN HSQC NMR showed that association perturbed the N‐domain of CaM more than its C‐domain. NMR resonance assignments of CaM and βCaNp, and interpretation of intermolecular NOEs observed in the 13C‐edited and 12C‐14N‐filtered 3D NOESY spectrum indicated anti‐parallel binding. The sole aromatic residue (Phe) located near the βCaNp C‐terminus was in close contact with several residues of the N‐domain of CaM outside the hydrophobic cleft. These structural and thermodynamic properties would permit the domains of CaM to have distinct physiological roles in regulating activation of βCaN. Proteins 2011. © 2010 Wiley‐Liss, Inc.
Effects of somatic mutations on CDR loop flexibility during affinity maturation
Authors: Wong Sergio E. , Sellers Ben D. , Jacobson Matthew P. 
Published: October 2010

AbstractPrior studies suggest that antibody affinity maturation is achieved, in part, via prearranging the CDRs for binding. The implication is that the entropy cost of binding is reduced and that this rigidification occurs as a consequence of somatic mutations during maturation. However, how these mutations modulate CDR flexibility is unclear. Here, molecular dynamics simulations captured CDR flexibility differences between four mature antibodies (7G12, AZ28, 28B4, and 48G7) and their germline predecessors. Analysis of their trajectories: (1) rationalized how mutations during affinity maturation restrict CDR motility, (2) captured the equilibrium between bound and unbound conformations for the H3 loop of unliganded 7G12, and (3) predicted a set of new mutations that, according to our simulations, should diminish binding by increasing flexibility. Proteins 2011. © 2010 Wiley‐Liss, Inc.
Hopping and radiative recombination at localized band tail states in hydro‐ genated amorphous silicon
Authors: Murayama Kazuro 
Published: October 2010

AbstractThe primary photocurrent in hydrogenated amorphous silicon (a‐Si:H) is shown to be due to the hopping controlled by deep localized band tail states from the time‐of‐flight (TOF) experiment and the Monte Carlo simulation. The power law decay of the luminescence observed at temperatures higher than 70 K is shown to be due to the recombination between the trapped hole and the electron making the hopping randomwalk at localized band tail states. The luminescence center in a‐Si:H is shown to be the hydrogen‐free Si nanostructures from the comparison with the luminescence from the Si nano‐particles in the porous Si (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Screened excitons in strained wurtzite AlxGa1–xN/GaN/AlyGa1–yN quantum wells
Authors: Ha S. H. , Ban S. L. , Zhu J. 
Published: October 2010

AbstractThe binding energies of heavy‐hole excitons in asymmetric strained wurtzite Alx Ga1‐xN/GaN/Aly Ga1‐yN quantum wells are investigated theoretically with a variational method and a self‐consistent procedure. The screening effect due to the 2‐dimensional electron‐hole gas and the built‐in electric field produced by spontaneous and strain‐induced piezoelectric polarization are considered in our calculation. The result indicates that the strong built‐in electric field is modulated obviously by the well width, barrier thickness and Al content. The decrease of well width increases the absolute value of built‐in electric field in the well layer, but reduces the strength of the field in barrier layers. The calculated results are found in agreement with previous works in symmetric structures but the strong built‐in electric field modulated by the barrier thickness and Al content results in the reduction of the excitonic binding energy in asymmetric ones. It is also found that the screening effect on the coloumbic interaction of electron and hole is stronger than on the built‐in electric field, leading to a reduction of excitonic stability (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of strain and hydrostatic pressure on the binding energy of excitons in wurtzite cylindrical quantum dots
Authors: Shi Lei , Yan Zu Wei 
Published: October 2010

AbstractA variational method is used to discuss the binding energies of excitons in a strained wurtzite cylindrical quantum dot by considering the hydrostatic pressure effect. Besides the built‐in electric field due to the spontaneous and piezoelectric polarizations, the strain dependence of parameters is also considered in our calculation. The results indicate that the binding energies of excitons with strain effect are higher than that without strain effect when the quantum dot height is small, but the binding energy with strain effect becomes lower than that without strain effect as the quantum dot height increases. The contribution from the built‐in electric field to the strain effect is dominant, but the contribution from the strain dependence of parameters is quite small (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anomalous detection‐energy dependence of coherent phonon in bismuth thin films
Authors: Morishita Ryosuke , Oohata Goro , Mizoguchi Kohji 
Published: October 2010

AbstractCoherent phonons in semimetal Bi thin films have been studied by using a spectrally‐resolved pump‐probe technique. It is found that the intensity of the coherent phonon with A1g symmetry in the Bi thin film changes with the detection energy. The detection‐energy dependence of the coherent phonon intensity indicates that the phonon intensity has two peaks at the energies shifted by about twice the phonon energy from the central energy of the pulse laser. We discuss the origin of the detection‐energy dependence of the phonon intensity from the viewpoint of the generation mechanism of the coherent phonon. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control of coherent vibronic oscillations in β‐carotene by ultrashort laser pulses
Authors: Sugisaki Mitsuru , Kosumi Daisuke , Saito Keisuke , Cogdell Richard J. , Hashimoto Hideki 
Published: October 2010

AbstractThe nonlinear optical responses of carotenoids can be investigated by means of the four‐wave mixing (FWM) spectroscopy. Here we especially focus on the relationship among the pulse sequences, temporal separations between the pulses and the resulting coherent signals. In the transient grating configuration, coherent oscillations with a period of a few tens femtoseconds are clearly observed, which reflect nuclear motions in the ground state. Interestingly, it was found that the Raman inactive modes can be excited by properly controlling the temporal separation of the first and second excitation pulses. The amplitudes of these oscillations are more than three orders of magnitude stronger in comparison with the predicted values obtained by well‐established quantum mechanical calculations. We propose a model to explain our finding that takes the state mixing between S2 and Sx and the higher‐order interaction of the electron‐phonon coupling into consideration. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of hydroxyfullerene on the structure of water
Authors: Khokhriakov Nicolai , Kodolov Vladimir 
Published: October 2010

AbstractThe interaction of hydroxyfullerene with water molecules is investigated in the frameworks of ab initio and semiempirical methods of quantum chemistry. The calculations demonstrate that the energy of cluster interaction with a water is twice as much as the energy of interaction between water molecules. Thus qualitative changes in the water structure take place when introducing small quantities of hydroxyfullerene. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Effect of Molecular Adsorption on the Electrical Conductance of Single Au Nanowires Fabricated by Electron‐Beam Lithography and Focused Ion Beam Etching
Authors: Shi Ping , Zhang Jingying , Lin Hsin‐Yu , Bohn Paul W. 
Published: October 2010

AbstractMetal nanowires are one of the potential candidates for nanostructured sensing elements used in future portable devices for chemical detection; however, the optimal methods for fabrication have yet to be fully explored. Two routes to nanowire fabrication, electron‐beam lithography (EBL) and focused ion beam (FIB) etching, are studied, and their electrical and chemical sensing properties are compared. Although nanowires fabricated by both techniques exhibit ohmic conductance, I–V characterization indicates that nanowires fabricated by FIB etching exhibit abnormally high resistivity. In addition, the resistivity of nanowires fabricated by FIB etching shows very low sensitivity toward molecular adsorption, while those fabricated by EBL exhibit sensitive resistance change upon exposure to solution‐phase adsorbates. The mean grain sizes of nanowires prepared by FIB etching are much smaller than those fabricated by EBL, so their resistance is dominated by grain‐boundary scattering. As a result, these nanowires are much less sensitive to molecular adsorption, which mediates nanowire conduction through surface scattering. The much reduced mean grain sizes of these nanowires correlate with Ga ion damage caused during the ion milling process. Thus, even though the nanowires prepared by FIB etching can be smaller than their EBL counterparts, their reduced sensitivity to adsorption suggests that nanowires produced by EBL are preferred for chemical and biochemical sensing applications.
Applying evolutionary perspective to analyse the TFT‐LCD industry development in Taiwan
Authors: Hsiao Chih‐Tung , Chang Pao‐Long , Ho Shu‐Ping 
Published: October 2010

AbstractAfter developing thin film transistor liquid crystal display (TFT‐LCD) technology for the past 30 years, Taiwan has become the largest LCD manufacturer globally. Even under the global financial crisis in 2008, the production value of 10‐inch or larger TFT‐LCD panels in Taiwan was still up to US$28.8 billion. The development of the LCD industry is dynamic and sophisticated, and the development trajectories are influenced by the strategies of internationally based parent factories supplying technology, the industry policies of the government and the interactions of TFT‐LCD companies with both their technology providers and upstream and downstream companies. Based on their interactions, these factors generate a unique evolutionary pathway, manifested in both ‘incidental’ and ‘inevitable’ results. This study adopts a holistic and evolutionary perspective to present the structure of industrial development systems and the evolutionary model in Newly Industrialized Countries (NICs). The structure of industrial development systems and the evolutionary model are applied to explore the development process and structure of the Taiwanese TFT‐LCD industry, and to interpret the behaviour of the self‐conscious evolution. The study suggests that the Taiwanese TFT‐LCD industry has experienced three stages of evolution, namely the adaptive evolution in the first two stages and changes into the still continuous self‐conscious evolution stage at present to respond to the possible change of the environment in the future and to obtain the greatest competition chance. Copyright © 2010 John Wiley & Sons, Ltd.
Dietary Monounsaturated Fatty Acids but not Saturated Fatty Acids Preserve the Insulin Signaling Pathway via IRS‐1/PI3K in Rat Skeletal Muscle
Authors: Moon Jae Hoon , Lee Ji Young , Kang Saet Byol , Park Jong Suk , Lee Byung Wan , Kang Eun Seok , Ahn Chul Woo , Lee Hyun Chul , Cha Bong Soo 
Published: October 2010

AbstractSaturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) show different effects on the development of insulin resistance. In this study, we compared the effect of dietary SFA and MUFA on the insulin signaling pathway in the skeletal muscle of a type 2 diabetic animal model. Twenty‐nine‐week‐old male Otsuka Long‐Evans Tokushima fatty (OLETF) rats were randomly divided into three groups and fed one of the following diets for 3 weeks; a normal chow diet, an SFA (lard oil) enriched or a MUFA (olive oil) enriched high‐fat diet. The vastus lateralis muscle was used for analyses. Insulin tolerance test showed improved insulin sensitivity in rats fed the MUFA diet, as compared to those fed the SFA diet (p < 0.001). The SFA diet reduced IRS‐1 expression and phosphorylated PI3K levels in skeletal muscle, as compared with a chow diet (p < 0.001, respectively). On the contrary, muscle IRS‐2 expression and phosphorylated ERK1/2 was significantly increased in rats fed the SFA diet (p < 0.001, respectively). Membrane translocation of glucose transporter type 4 decreased in the skeletal muscle of rats fed the SFA diet, as compared to those fed a chow diet (p < 0.001). These changes in insulin signaling pathway in skeletal muscle were not observed in rats fed the MUFA diet. In conclusion, the beneficial effect of dietary MUFA on insulin sensitivity is associated with a conserved IRS‐1/PI3K insulin signaling pathway which was altered by dietary SFA.