bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved radial basis function fluid–structure coupling via efficient localized implementation
Authors: Rendall T. C. S. , Allen C. B. 
Published: January 2009

AbstractPrevious work by the authors has developed a universal interpolation scheme, using radial basis functions (RBFs), which results in a unified formulation for robust fluid–structure interpolation and high‐quality mesh motion. The method has several significant advantages. Primarily, all volume mesh, structural mesh, and flow‐solver‐type dependence is removed entirely, as all operations are performed on totally arbitrary point clouds of any form. Hence, all connectivity requirements are removed from both the coupling and mesh motion problems. Furthermore, only matrix‐vector multiplications are required during unsteady simulation because dependence relations are computed once prior to any simulation and then remain constant. This property means that the method is both perfectly parallel and totally independent from the flow‐solver. However, the full method is expensive, since the dependence matrix between two sets of points is N × N. The fluid–structure coupling behaviour can also be influenced by parameters used in the interpolation. To alleviate these difficulties a more efficient form of the RBF fluid–structure coupling is presented, which also greatly reduces the interpolation parameter influence. A pointwise form of the partition of unity approach is developed that localizes the interpolation, with results presented for static aeroelastic simulations of the Brite‐Euram multi‐disciplinary optimization wing using a very fine mesh containing 58 000 surface points. It is shown that a 58 × reduction in data size is achieved, and equally importantly the interpolation has a much smaller influence on final aeroelastic results. Copyright © 2009 John Wiley & Sons, Ltd.
The numerical solution of the second Painlevé equation
Authors: Dehghan Mehdi , Shakeri Fatemeh 
Published: January 2009

AbstractThe Painlevé equations were discovered by Painlevé, Gambier and their colleagues during studying a nonlinear second‐order ordinary differential equation. The six equations which bear Painlevé's name are irreducible in the sense that their general solutions cannot be expressed in terms of known functions. Painlevé has derived these equations on the sole requirement that their solutions should be free from movable singularities. Many situations in mathematical physics reduce ultimately to Painlevé equations: applications including statistical mechanics, plasma physics, nonlinear waves, quantum gravity, quantum field theory, general relativity, nonlinear optics, and fiber optics. This fact has caused a significant interest to the study of these equations in recent years. In this study, the solution of the second Painlevé equation is investigated by means of Adomian decomposition method, homotopy perturbation method, and Legendre tau method. Then a numerical evaluation and comparison with the results obtained by the method of continuous analytic continuation are included. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
Synthesis of surface‐initiated polymer brushes using macro‐initiators
Authors: Edmondson Steve , Armes Steven P 
Published: January 2009

AbstractThe synthesis of polymer brushes using surface‐adsorbed macro‐initiators is briefly reviewed, with particular emphasis being placed on the combination of atom transfer radical polymerisation with polyelectrolytic macro‐initiators. The latter contain 2‐bromoester initiator groups and can be readily prepared with either cationic or anionic character from (co)polymer precursors. Such macro‐initiators offer convenient functionalisation of a wide range of colloidal and planar charged surfaces such as silica, mica, alumina or tin(IV) oxide, since electrostatic adsorption occurs rapidly from aqueous solution at room temperature. A wide range of hydrophilic methacrylic polymer brushes have been grown from these macro‐initiators, offering potential applications in surface lubricity and tribology, tuneable surface (de)wetting and cell detachment. In some cases surface degrafting can occur if thicker polymer brushes are targeted. However, this problem can be circumvented if pairs of oppositely charged polyelectrolytic macro‐initiators are used to build up ionically crosslinked multilayers via layer‐by‐layer self‐assembly. This facile approach to surface functionalisation appears to be steadily growing in popularity and has now been adopted by a number of research groups in several countries. Copyright © 2009 Society of Chemical Industry
Synthesis and properties of sulfonated polyimides derived from bis(sulfophenoxy) benzidines
Authors: Sutou Yoshiki , Yin Yan , Hu Zhaoxia , Chen Shouwen , Kita Hidetoshi , Okamoto Ken‐Ichi , Wang Hongyuan , Kawasato Hironobu 
Published: January 2009

AbstractA series of aromatic sulfonated polyimides (SPIs) bearing sulfophenoxy side groups have been successfully synthesized and evaluated as polymer electrolyte membranes for fuel cell applications. The SPIs had high viscosity and gave tough and flexible membranes. The SPI membranes showed anisotropic membrane swelling in water with much larger dimensional change in thickness direction than in plane one. They showed the better proton‐conducting performance even in the lower relative humidity (RH) range than the other SPI membranes, for example, a high proton conductivity of 0.05 S/cm at 50 % RH and 120 °C. They maintained high mechanical strength and conductivity after aging in water at 130 °C for 500 h, showing much better water stability compared with the main‐chain‐type SPI and side‐chain‐type SPI membranes reported so far. In polymer electrolyte fuel cells (PEFCs) operated at 90 °C and 84–30%RH, they showed fairly high cell performances and have high potential for PEFC applications. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1463–1477, 2009
Hydrobromination of residual vinyl groups on divinylbenzene polymer particles followed by atom transfer radical surface graft polymerization
Authors: Limé Fredrik , Irgum Knut 
Published: January 2009

AbstractRigid and monodisperse spherical polymer particles with 2.36 ± 0.18 μm diameter containing residual surface vinyl groups were prepared by photoinitiated precipitation polymerization of divinylbenzene. Anti‐Markovnikov addition of HBr to the surface vinyl groups yielded a 2‐bromoethyl functionality that was used as macroinitiator for atom transfer radical polymerization (ATRP), providing the possibility for further functionalization by controlled “grafting from” processes. This was demonstrated by grafting of glycidyl methacrylate brushes from the particle surface, using an ATRP system based on CuBr and pentamethyl diethylenetriamine. Existence of a methacrylic overlayer was verified by FTIR and XPS measurements, and the grafted particles were easily dispersed in water, confirming conversion of the particle surface from hydrophobic to hydrophilic. Hydrobromination of residual vinyl groups yields a macroinitiator that can be used for grafting of glycidyl methacrylate by ATRP. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1259–1265, 2009
Amphiphilic conetworks. IV. Poly(methacrylic acid)‐l‐polyisobutylene and poly(acrylic acid)‐l‐polyisobutylene based hydrogels prepared by two‐step polymer procedure. New pH responsive conetworks
Authors: Toman Ludĕk , Janata Miroslav , Spĕváček Jiří , Brus Jiří , Sikora Antonín , Horský Jiří , Vlček Petr , Látalová Petra 
Published: January 2009

AbstractThis article describes the synthesis and characterization of new amphiphilic polymer conetworks containing hydrophilic poly(methacrylic acid) (PMAA) or poly(acrylic acid) (PAA) and hydrophobic polyisobutylene (PIB) chains. These conetworks were prepared by a two‐step polymer synthesis. In the first step, a cationic copolymer of isobutylene (IB) and 3‐isopropenyl‐α,α‐dimethylbenzyl isocyanate (IDI) was prepared. The isocyanate groups of the IB–IDI random copolymer were subsequently transformed in situ to methacrylate (MA) groups in reaction with 2‐hydroxyethyl methacrylate (HEMA). In the second step, the resulting MA‐multifunctional PIB‐based crosslinker, PIB(MA)n, with an average functionality of approximately four methacrylic groups per chain, was copolymerized with methacrylic acid (MAA) or acrylic acid (AA) by radical mechanism in tetrahydrofuran giving rise to amphiphilic conetworks containing 31–79 mol % of MAA or 26–36 mol % of AA. The synthesized conetworks were characterized with solid‐state 13C‐NMR spectroscopy and differential scanning calorimetry. The amphiphilic nature of the conetworks was proven by swelling in both aqueous media with low and high pH and n‐heptane. The effect of varying pH on the swelling behavior of the synthesized conetworks is presented. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1284–1291, 2009
Poly(ether tert‐amine): A novel family of multiresponsive polymer
Authors: Ren Yanrong , Jiang Xuesong , Yin Jie 
Published: January 2009

AbstractA novel multiresponsive poly(ether tert‐amine) (PEA) was synthesized by nucleophilic addition/ring‐opening reaction of commercial poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), and di‐epoxy and di‐amine monomer. The process of synthesis was very simple and green in ethanol as reactive media. These PEAs exhibit sharp response to temperature, pH, and ionic strength, with adjustable and sharp phase transitions in the range of 27–100 °C. The lower critical solution temperature (LCST) of PEA's aqueous solution presents a linear relationship to the PEO content (y = 35.7 + x), indicating well‐tunable LCST. The concentration of PEA has no obvious effect on LCST. Therefore, PEA will be potential in applications of drug delivery, separation, and biotechnology. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1292–1297, 2009
All‐aromatic liquid crystalline thermosets with high glass transition temperatures
Authors: Iqbal Mazhar , Norder Ben , Mendes Eduardo , Dingemans Theo J. 
Published: January 2009

AbstractWe have synthesized and characterized a new family of low melting all‐aromatic ester‐based liquid crystal oligomers end‐capped with reactive phenylethynyl end groups. In a consecutive, high‐temperature step, the reactive end groups were thermally activated and polymerization was initiated. This reactive oligomer approach allows us to synthesize liquid crystal thermosets with outstanding mechanical and thermal properties, which are superior to well‐known high‐performance polymers such as PPS and PEEK. We have modified an intractable LC formulation based on hydroquinone and terephthalic acid, with Mn = 1000, 5000, and 9000 g mol−1, and varied the backbone composition using isophthalic acid, resorcinol, 4‐hydroxy‐benzoic acid, 6‐hydroxy‐2‐naphthoic acid, and chlorohydroquinone. All fully cured polymers showed glass transition temperatures in the range of 164–275 °C, and high storage moduli at room temperature (∼ 5 GPa) and elevated temperature (∼ 2 GPa at 200 °C). All oligomers display nematic mesophases and in most cases, the nematic order is maintained after cure. Rheology experiments showed that the phenylethynyl end group undergoes predominantly chain extension below 340 °C and crosslinking above this temperature. Highly aligned fibers could be spun from the nematic melt, and we found that the order parameter 〈P2〉 was not affected by the chain extension and crosslink chemistry. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1368–1380, 2009
Analysis of association constant for ground‐state dye‐electron acceptor complex of photoinitiator systems and the association constant effect on the kinetics of visible‐light‐induced polymerizations
Authors: Kim Dongkwan , Scranton Alec B. , Stansbury Jeffrey W. 
Published: January 2009

AbstractWe investigated the formation of ground‐state donor/acceptor complexes between xanthene dyes [rose bengal (RB) and fluorescein (FL)] and a diphenyliodonium (DPI) salt, which is dissolved in 2‐hydroxyethyl methacrylate (HEMA) monomer. To characterize the association constant of the complex, we have suggested a new analysis model based upon the Benesi–Hildebrand model. Because the assumption of the original Benesi–Hildebrand model is that the absorption bands are only due to the presence of the complex and that the absorption by the free component is negligible, the model cannot be applied to our systems, which is a dye‐based initiator system. For each dye, the molar absorptivity of the ground‐state complex was evaluated as a function of wavelength, and this analysis confirmed the validity of the modified Benesi–Hildebrand model. In addition, we observed that the RB/DPI photoinitiator system failed to produce a perceptible polymerization rate but the FL/DPI photoinitiator system provided high rates of polymerization. On the basis of the association constant for these complexes, we concluded that the observed kinetic differences arise from the different association constant values of the ground‐state dye‐acceptor complex, resulting in back‐electron transfer reaction. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1429–1439, 2009
Synthesis of PEG‐PNIPAM‐PLys hetero‐arm star polymer and its variation of thermo‐responsibility after the formation of polyelectrolyte complex micelles with PAA
Authors: Li Jian , He Wei‐Dong , He Ning , Han Shou‐Chen , Sun Xiao‐Li , Li Li‐Ying , Zhang Bo‐Yu 
Published: January 2009

AbstractA hetero‐arm star polymer, poly(ethylene glycol)‐poly(N‐isopropylacrylamide)‐poly(L‐lysine) (PEG‐PNIPAM‐PLys), was synthesized by “clicking” the azide group at the junction of PEG‐b‐PNIPAM diblock copolymer with the alkyne end‐group of poly(L‐lysine) (PLys) homopolymer via 1,3‐dipolar cycloaddition. The resultant polymer was characterized by gel permeation chromatography, proton nuclear magnetic resonance, and Fourier transform infrared spectroscopes. Surprisingly, the PNIPAM arm of this hetero‐arm star polymer nearly lose its thermal responsibility. It is found that stable polyelectrolyte complex micelles are formed when mixing the synthesized polymer with poly(acrylic acid) (PAA) in water. The resultant polyelectrolyte complex micelles are core‐shell spheres with the ion‐bonded PLys/PAA chains as core and the PEG and PNIPAM chains as shell. The PNIPAM shell is, as expected, thermally responsive. However, its lower critical solution temperature is shifted to 37.5 °C, presumably because of the existence of hydrophilic components in the micelles. Such star‐like PEG‐PNIPAM‐PLys polymer with different functional arms as well as its complexation with anionic polymers provides an excellent and well‐defined model for the design of nonviral vectors to deliver DNA, RNA, and anionic molecular medicines. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1450–1462, 2009
Formation of the RFX gene regulatory complex induces folding of the interaction domain of RFXAP
Authors: Briggs LaTese , Laird Kholiswa , Boss Jeremy M. , Garvie Colin W. 
Published: January 2009

AbstractMajor histocompatibility complex class II (MHCII) molecules have a central role in the mammalian adaptive immune response against infection. The level of the immune response is directly related to the concentration of MHCII molecules in the cell, which have a central role in initiating the immune response. MHCII molecules are therefore a potential target for the development of immunosuppressant drugs for the treatment of organ transplant rejection and autoimmune disease. The expression of MHCII molecules is regulated by a cell specific multiprotein complex. The RFX complex is the key DNA binding component of this complex. The RFX complex is composed of three proteins—RFX5, RFXAP, and RFXB—all of which are required for activation of expression of the MHCII genes. Little is currently known about the precise regions of the RFX proteins that are required for complex formation, or their structure. We have therefore identified the key regions of RFX5, RFXAP, and RFXB, which are required to form the RFX complex and have characterized the individual domains and the complexes they form using NMR and circular dichroism spectroscopy and isothermal titration calorimetry. Our results support a model for the assembly of the RFX complex in which the interaction between RFX5 and RFXAP promote folding of a poorly structured region ofRFXAP, which is required for high affinity binding of RFXB to the RFX5·RFXAP complex. Proteins 2009. © 2009 Wiley‐Liss, Inc.
REMO: A new protocol to refine full atomic protein models from C‐alpha traces by optimizing hydrogen‐bonding networks
Authors: Li Yunqi , Zhang Yang 
Published: January 2009

AbstractProtein structure prediction approaches usually perform modeling simulations based on reduced representation of protein structures. For biological utilizations, it is an important step to construct full atomic models from the reduced structure decoys. Most of the current full atomic model reconstruction procedures have defects which either could not completely remove the steric clashes among backbone atoms or generate final atomic models with worse topology similarity relative to the native structures than the reduced models. In this work, we develop a new protocol, called REMO, to generate full atomic protein models by optimizing the hydrogen‐bonding network with basic fragments matched from a newly constructed backbone isomer library of solved protein structures. The algorithm is benchmarked on 230 nonhomologous proteins with reduced structure decoys generated by I‐TASSER simulations. The results show that REMO has a significant ability to remove steric clashes, and meanwhile retains good topology of the reduced model. The hydrogen‐bonding network of the final models is dramatically improved during the procedure. The REMO algorithm has been exploited in the recent CASP8 experiment which demonstrated significant improvements of the I‐TASSER models in both atomic‐level structural refinement and hydrogen‐bonding network construction. Proteins 2009. © 2009 Wiley‐Liss, Inc.
De novoidentification of binding sequences for antibody replacement molecules
Authors: Quirk Stephen , Zhong Shi , Hernandez Rigoberto 
Published: January 2009

AbstractA newin silicomethod has been developed that automatically identifies peptide sequences that can bind to targets of known three‐dimensional structure. The method is potentially faster and more economical than traditional methods of raising antibodies by means of hybridomas or biopanning technology. The current algorithm creates an initial peptide library that is either completely random or that is constrained by the user. This library represents only a small fraction of possible sequence space and the peptides are created with a specified torsional geometry. The library is used as input to any number of available molecular docking programs and the library is docked and scored. The final rank ordering is then used to create a new library by constraining that library to the sequence conservation pattern deduced from the topN‐scoring peptides in the first round. Successive rounds of screening, scoring, and new library creation ultimately results in the system converging to a final solution set of peptides. To test the method, a family of novel peptides that can bind to, and inhibit the enzyme Deoxyribonuclease I has been discovered. The peptides inhibit the enzyme either alone or when placed into a protein backbone structure as has been confirmed experimentally. Proteins 2009. © 2009 Wiley‐Liss, Inc.
Low glyphosate rates do not affect Citrus limonia (L.) Osbeck seedlings
Authors: Gravena Renan , Victoria Filho Ricardo , Alves Pedro Luis CA , Mazzafera Paulo , Gravena Adriana R 
Published: January 2009

AbstractBACKGROUND: Glyphosate is used to control weeds in citrus orchards, and accidental spraying or wind drift onto the seedlings may cause growth arrest owing to metabolism disturbance. Two experiments were carried out to investigate the effect of non‐lethal rates (0, 180, 360 and 720 g AI ha−1) of glyphosate on four‐month‐old ‘Cravo’ lime, Citrus limonia (L.) Osbeck, seedlings. Photosynthesis and the concentrations of shikimic acid, total free amino acids and phenolic acids were evaluated.RESULTS: Only transitory effects were observed in the contents of shikimate and total free amino acids. No visual effects were observed.CONCLUSION: The present study showed that glyphosate at non‐lethal rates, which is very usual when accidental spraying or wind drift occurs in citrus orchard, did not cause severe metabolic damage in ‘Cravo’ lime seedlings. Copyright © 2009 Society of Chemical Industry
Anisotropy of thermal vibrations and polymorphic transformations in lanthanum and uranium
Authors: Blanter M. S. , Glazkov V. P. , Somenkov V. A. 
Published: January 2009

AbstractAverage thermal atomic displacements along different crystallographic axes were measured for polycrystalline samples employing the method of neutron diffraction and defining the anisotropic Debye–Waller factor, obtained by processing the corresponding reflections. In the double hexagonal close‐packed lanthanum modification, the anisotropy of vibrations is insignificant at room temperature, yet it increases markedly with increasing temperature; also, the relative displacement (in relation to the corresponding lattice parameters) in the basal plane considerably exceeds that along the hexagonal axis. In orthorhombic α‐uranium, large anisotropy is observed even at room temperature, which increases with increasing temperature. It is clearly proved that in lanthanum and uranium the polymorphic transition of low‐temperature anisotropic phases into high‐temperature cubic modifications with isotropic thermal vibrations reduces the maximum relative quantity of thermal displacements at the expense of more homogeneous distribution of vibrations along the lattice axes, and thus probably ‘prevents’ the melting of low‐temperature modifications at a lower temperature due to the critical value of these displacements being reached. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Antifungal activity of Glycyrrhiza glabra extracts and its active constituent glabridin
Authors: Fatima Atiya , Gupta Vivek K. , Luqman Suaib , Negi Arvind S. , Kumar J. K. , Shanker Karuna , Saikia Dharmendra , Srivastava Suchita , Darokar M. P. , Khanuja Suman P.S. 
Published: January 2009

AbstractGlabridin, an active constituent of Glycyrrhiza glabra roots, was found to be active against both yeast and filamentous fungi. Glabridin also showed resistance modifying activity against drug resistant mutants of Candida albicans at a minimum inhibitory concentration of 31.25–250 µg/mL. Although the compound was reported earlier to be active against Candida albicans, but this is the first report of its activity against drug resistant mutants. Copyright © 2009 John Wiley & Sons, Ltd.