bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic vulcanization of polyethylene‐based thermoplastic elastomer blends
Authors: Sarkhel Gautam , Choudhury Arup 
Published: September 2009

AbstractIn this investigation, the effects of blending with ethylene–propylene–diene terpolymer and subsequent dynamic curing with sulfur on the macromolecular structure and properties of pure low‐density polyethylene and high‐density polyethylene were studied. The crosslinking efficiency of polyethylene‐based ethylene–propylene–diene terpolymer blends upon dynamic curing was assessed with torque and gel content measurements. The curing of dispersed ethylene–propylene–diene terpolymer in a polyethylene matrix improved both the mechanical and thermomechanical properties as a result of the formation of a crosslink structure in the rubber phase. In view of the electrical applications of this cured blend material, the volume resistivity was measured. The thermal stability of vulcanized polyethylene/ethylene–propylene–diene terpolymer blends was found to be superior to that of unvulcanized blends. In scanning electron microscopy analysis, good interface bonding between the polyethylene matrix and dispersed ethylene–propylene–diene terpolymer was observed for the cured blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Hydrogen bonding in blends of polyesters with dipeptide‐containing polyphosphazenes
Authors: Krogman Nicholas R. , Weikel Arlin L. , Nguyen Nhu Q. , Kristhart Katherine A. , Nukavarapu Syam P. , Nair Lakshmi S. , Laurencin Cato T. , Allcock Harry R. 
Published: September 2009

AbstractNew biomedically erodible polymer composites were investigated. Polyphosphazenes containing the dipeptide side groups alanyl–glycine ethyl ester, valinyl–glycine ethyl ester, and phenylalanyl–glycine ethyl ester were blended with poly(lactide‐co‐glycolide) (PLGA) with lactic to glycolic acid ratios of 50 : 50 [PLGA (50 : 50)] and 85 : 15 [PLGA (85 : 15)] with solution‐phase techniques. Each dipeptide ethyl ester side group contains two NH protons that are capable of hydrogen bonding with the carbonyl functions of PLGA. Polyphosphazenes that contain only the dipeptide ethyl ester groups are insoluble in organic solvents and are thus unsuitable for solution‐phase composite formation. To ensure solubility during and after synthesis, cosubstituted polymers with both dipeptide ethyl ester and glycine or alanine ethyl ester side groups were used. Solution casting or electrospinning was used to fabricate polymer blend matrices with different ratios of polyphosphazene to polyester, and their miscibilities were estimated with differential scanning calorimetry and scanning electron microscopy techniques. Polyphosphazenes with alanyl–glycine ethyl ester side groups plus the second cosubstituent were completely miscible with PLGA (50 : 50) and PLGA (85 : 15) when processed via solution‐casting techniques. This suggests that the hydrogen‐bonding protons in alanyl–glycine ethyl ester have access to the oxygen atoms of the carbonyl units in PLGA. However, when the same pair of polymers was electrospun from solution, the polymers proved to be immiscible. Solution‐cast miscible polymer blends were obtained from PLGA (50 : 50) plus the polyphosphazene that was cosubstituted with valinyl–glycine ethyl ester and glycine ethyl ester side groups. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Study on synthesis of polyurethane‐epoxy composite emulsion
Authors: Yi Ying , Ye Fayin , Huang Chou , Guan Jianguo 
Published: September 2009

AbstractThe stable polyurethane‐epoxy composite emulsion with the epoxy‐amine oligomer (DEA‐EP) and the epoxy resin oligomer has been prepared by step‐growth polymerization and controlled crosslinking technique. The emulsion forming transparent films can be cured at room temperature with trimethylolpropane tris (1‐ethyleneimine) propionate (TMPTA‐AZ). The DEA‐EP structure and its reaction with urethane prepolymers were proved by Fourier transform infrared spectra (FTIR). The studies on particle size, the particle size distribution, viscosity, and the films' transmittance (Tr) indicated that both trimethylol propane (TMP) and DEA‐EP contributed to improving the resin blends' compatibility and reducing the viscosity. The epoxy resin content can increase up to 20.0 wt % (based on the total content of the polyurethane and epoxy resin) and the emulsion was still stable. The data from the tensile test experiments showed that with the epoxy content increasing, the tensile strength (σb) and Young's modulus were proportionately raised, but the elongation at break (εb) decreased. Tensile tests also revealed that introducing TMPTA‐AZ as an outside‐crosslinker can increase the tensile strength. By adding 0.3 wt % of TMPTA‐AZ, the εb reduced from 429% to 371% and the σb increased from 4.4 to 13.73 MPa; by adding 1.8 wt % of TMPTA‐AZ, εb of the film was 67% of εb of the film with 0.3 wt % of TMPTA‐AZ, but its σb was 24.77 MPa and 180% of σb of the film with 0.3 wt % of TMPTA‐AZ. The cured films possessed excellent water and toluene resistance: water uptake (48 h, 3.1%; degree of curing: 70%), toluene uptake (210 h, 8%. degree of curing: 70%). Better properties of the composite emulsion will confer it as a potential application in low volatile industrial coatings. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Tracking customer portfolio composition: A factor analysis approach
Authors: Abascal Elena , García Lautre Ignacio , Mallor Fermín 
Published: September 2009

AbstractIn this paper, we address the changing composition of a customer portfolio taking into account actions undertaken by the company to adapt its service offer to market conditions and/or technological innovations. We present a specific methodology to identify clusters of customers in different periods and then compare them over time. The classification process takes into account both qualitative and quantitative aspects of the consumption levels of the services or products offered by the company. The possibility of period‐to‐period variation in the customer portfolio and the service or product offer is also considered, in order to achieve a more realistic scenario.The core of the proposed methodology is related to the family of exploratory factorial and cluster techniques. The customers are classified by using a bicriterial clustering methodology based on ‘tandem’ analysis (multiple factor analysis+cluster analysis of the main factors). The bicriterial approach allows for a compromise between customers' consumption levels (a quantitative criterion) and their consumption/non‐consumption pattern (a qualitative criterion). The evolution of the customer portfolio composition is explored through multiple correspondence analysis. This technique allows visual comparison of the position of different clusters against time and the identification of key changes in customer consumption behavior. The methodology is tested on realistic customer portfolio scenarios for a major telecommunication company. We simulate various scenarios to show the strengths of our proposal. Copyright © 2009 John Wiley & Sons, Ltd.
A nanosensory device fabricated on a liposome for detection of chemical signals
Authors: Sasaki Yoshihiro , Shioyama Yuka , Tian Wen‐Jie , Kikuchi Jun‐ichi , Hiyama Satoshi , Moritani Yuki , Suda Tatsuya 
Published: September 2009

AbstractThis paper describes construction of a nanosensory device for amplified detection of biologically important amines as chemical signals. The device was inspired by a biological signal transduction system, and was fabricated on an artificial cell membrane through self‐organization of the molecular components, such as a synthetic receptor and a natural enzyme. Selective recognition of biologically important amines was achieved by a synthetic receptor with a pyridoxal moiety, as evaluated by means of electronic absorption spectroscopy. The selectivity in detecting amines as chemical signals mainly depends on hydrophobicity of the amines. The event upon detecting the chemical signals was transmitted to an enzyme by a metal ion acting as a mediator species, and then the enzyme amplified the event by the catalytic reaction to obtain signal output. This paper is realization of a biomimetic signal transduction system using amines as chemical signals and may provide a useful guidepost for designing integrated nanosystems. Biotechnol. Bioeng. 2010;105: 37–43. © 2009 Wiley Periodicals, Inc.
Modeling the influence of cyclodextrins on oral absorption of low‐solubility drugs: I. Model development
Authors: Gamsiz Ece Dilber , Miller Lee , Thombre Avinash G. , Ahmed Imran , Carrier Rebecca Lyn 
Published: September 2009

AbstractThe ability to quantitatively predict the influence of a solubilization technology on oral absorption would be highly beneficial in rational selection of drug delivery technology and formulation design. Cyclodextrins (CDs) are cyclic oligosaccharides which form inclusion complexes with a large variety of compounds including drugs. There are many studies in the literature showing that complexation between CD and drug enhances oral bioavailability and some demonstrating failure of CD in bioavailability enhancement, but relatively little guidance regarding when CD can be used to enhance bioavailability. A model was developed based upon mass transport expressions for drug dissolution and absorption and a pseudo‐equilibrium assumption for the complexation reaction with CD. The model considers neutral compound delivered as a physical mixture with CD in both immediate release (IR) and controlled release (CR) formulations. Simulation results demonstrated that cyclodextrins can enhance, have no effect, or hurt drug absorption when delivered as a physical mixture with drug. The predicted influence depends on interacting parameter values, including solubility, drug absorption constant, binding constant, CD:drug molar ratio, dose, and assumed volume of the intestinal lumen. In general, the predicted positive influence of dosing as a physical mixture with CD was minimal, alluding to the significance of dosing as a preformed complex. The model developed enabled examination of which physical and chemical properties result in oral absorption enhancement for neutral drug administered as a physical mixture with CD, demonstrating the utility of modeling the influence of a drug delivery agent (e.g., CD) on absorption for rational dosage form design. Biotechnol. Bioeng. 2010; 105: 409–420. © 2009 Wiley Periodicals, Inc.
Aggregation of a monoclonal antibody induced by adsorption to stainless steel
Authors: Bee Jared S. , Davis Michele , Freund Erwin , Carpenter John F. , Randolph Theodore W. 
Published: September 2009

AbstractStainless steel is a ubiquitous surface in therapeutic protein production equipment and is also present as the needle in pre‐filled syringe biopharmaceutical products. Stainless steel microparticles can cause the aggregation of a monoclonal antibody (mAb). The initial rate of mAb aggregation was second order in steel surface area and zero order in mAb concentration, generally consistent with a bimolecular surface aggregation being the rate‐limiting step. Polysorbate 20 (PS20) suppressed the aggregation yet was unable to desorb the firmly bound first layer of protein that adsorbs to the stainless steel surface. Also, there was no exchange of mAb from the first adsorbed layer to the bulk phase, suggesting that the aggregation process actually occurs on subsequent adsorption layers. No oxidized Met residues were detected in the mass spectrum of a digest of a highly aggregated mAb, although there was a fourfold increase in carbonyl groups due to protein oxidation. Biotechnol. Bioeng. 2010;105: 121–129. © 2009 Wiley Periodicals, Inc.
Biosynthesis of silver nanoparticles using Eclipta leaf
Authors: Jha Anal K. , Prasad Kamlesh , Kumar Vikash , Prasad K. 
Published: September 2009

AbstractA green, low‐cost and reproducible Eclipta leaves negotiated synthesis of silver nanoparticles is reported. The synthesis is performed at room temperature. X‐ray and transmission electron microscopy analyses are performed to ascertain the formation of Ag nanoparticles. Nanoparticles almost spherical in shape having a size of 2–6 nm are found. UV‐visible study revealed the surface plasmon resonance at 419 nm. The lattice strain is estimated to be 0.0045 using Williamson‐Hall approach. The use of Eclipta for the synthesis of silver nanoparticles offers the benefit of ecofriendliness and amenability for large scale production through scaling up. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
The quaternary structure of tetrameric hemoglobin regulates the oxygen affinity of polymerized hemoglobin
Authors: Palmer Andre F. , Sun Guoyong , Harris David R. 
Published: September 2009

AbstractThis study focuses on the effect of the initial quaternary structure of bovine hemoglobin (Hb) on the physical properties of glutaraldehyde polymerized Hb (PolyHb) solutions. Tense (T) state PolyHb was synthesized by maintaining the pO2 of Hb before and after polymerization at 0 mm Hg. In contrast, relaxed (R) state PolyHb was generated by maintaining the pO2 of Hb before and after polymerization to >749 mm Hg. PolyHb solutions were characterized by measuring the pO2, methemoglobin (metHb) level, molecular weight distribution, O2 affinity and cooperativity coefficient. The metHb level of all PolyHb solutions was low (<2%). Analysis of the molecular weight distribution of PolyHb solutions indicates that in general, the molecular weight of PolyHb solutions increased with increasing cross‐link density. T‐state PolyHb solutions exhibited lower O2 affinity compared to unmodified Hb, whereas R‐state PolyHb solutions exhibited higher O2 affinity compared to unmodified Hb. In addition, the polymerization reaction resulted in a significant decrease in cooperativity that was more pronounced at higher cross‐link densities. All of these results were explained in terms of the quaternary structure of Hb. Taken together, our results yield more insight into the importance Hb's quaternary structure plays in defining the physical properties of glutaraldehyde PolyHb solutions. This information will be useful in designing optimized glutaraldehyde PolyHb oxygen carriers for various applications in transfusion medicine. © 2009 American Institute of Chemical Engineers Biotechnol. Prog. 2009
Local communities responding to ecological challenges—A psycho‐social approach to the Natura 2000 Network
Authors: Mouro Carla , Castro Paula 
Published: September 2009

AbstractThe institutionalization of biodiversity conservation through legal instruments has led to mixed reactions at both the individual and community levels, with conflict and resistance co‐existing with support. The overall purpose of this paper is to describe how rural communities living in areas included in the Natura 2000 Network of protected sites, where local practices of land use are regulated by new legal directives, receive biodiversity conservation goals. Previous studies suggest that this reception is strongly shaped by place identification, but their contradictory results demand further clarification. This study examines the role of psycho‐social variables identified by previous studies as potentially relevant moderators of identification: (a) Vested interest in natural resources, (b) evaluation of the designation process of protected areas and (c) institutional trust. It further extends previous research by analysing the support given to contextually relevant ecological practices. Results reveal a positive link between place identification and attitudes in the high vested interest condition and show that support for conservation practices is better predicted in the high vested interest and low trust conditions. The discussion focuses on the relevance of analysing contextually relevant psycho‐social moderators when attempting to understand how local communities' relation with biodiversity conservation is affected by legislative innovation. Copyright © 2009 John Wiley & Sons, Ltd.
Transition from EcoDam to T4Dam DNA Recognition Mechanism without Loss of Activity and Specificity
Authors: Elsawy Hany , Podobinschi Sveatoslav , Chahar Sanjay , Jeltsch Albert 
Published: September 2009

AbstractThe EcoDam and T4Dam DNA‐(adenine N6)‐methyltransferases both methylate the adenine residue in GATC sites. These enzymes are highly related in amino acid sequence, but they deviate in their contact to the first base pair of the target sequence. EcoDam contacts Gua1 with K9 (which corresponds to T4Dam A6), while T4Dam contacts Gua1 with R130 (which corresponds to EcoDam Y138). We have “transplanted” the T4Dam DNA recognition into EcoDam and show that the EcoDam K9A/Y138R double mutant is highly active and specific. We also studied the intermediates of this transition: The EcoDam K9A variant showed low activity and loss of recognition of Gua1 [Horton, et al., J. Mol. Biol. 2006, 358, 559–570]. In contrast, the EcoDam Y138R variant, which carries both Gua1 recognition elements (K9 from EcoDam and R138 corresponding to R130 from T4Dam), is fully active and specific. This result indicates that a smooth evolutionary pathway exists for changing the EcoDam DNA recognition mode to T4Dam without loss of activity and without generation of evolutionary intermediates with reduced activity. We consistently observed increased activity of EcoDam variants containing Y138R; this suggests that the transition from EcoDam (Gua1 recognition through K9) to T4Dam (Gua1 recognition through R130) was driven by selective pressure towards increased catalytic activity.
A DFT Study of CO Catalytic Oxidation by N2O or O2 on the Co3O4(110) Surface
Authors: Xu Xiang‐Lan , Yang E , Li Jun‐Qian , Li Yi , Chen Wen‐Kai 
Published: September 2009

AbstractThe reaction mechanisms for CO catalytic oxidation by N2O or O2 on the Co3O4(110) surface were studied by DFT slab calculations. CO chemisorbs preferably at a surface Co3+ site. After the Co3+ site is completely covered, CO adsorbs at the neighboring twofold coordinated surface oxygen atom bonded to Co2+ and Co3+ cations, resulting in the formation of CO2 and an oxygen vacancy with a low energy barrier of 0.033 eV, which rationalizes the experimental observation that Co3O4‐based systems are active for CO oxidation at low temperatures. N2O or O2 interacts with the oxygen vacancy site to regenerate the surface, leaving N2 or the activated O2− species to be attacked by the second CO to yield CO2 to proceed with the catalytic cycle. The CO oxidation reaction follows the Mars– van Krevelen mechanism.
Calix[4]arene‐Phosphine Dimers: Precursors of Flexible Metallo‐Capsules and Self‐Compacting Molecules
Authors: Sameni Soheila , Jeunesse Catherine , Matt Dominique , Toupet Loïc 
Published: September 2009

AbstractThe first diphosphines based on a double calixarene, namely 1,4 (or 1,3)‐bis‐(5‐diphenylphosphino‐25,26,27,28‐tetrapropoxycalix[4]aren‐17‐yl)benzene (L2, L3) were each prepared in four steps starting from 5,17‐dibromo‐25,26,27,28‐tetrapropoxycalix[4]arene. Upon reaction of L2 with [Au(tht)(thf)]BF4, (tht=C4H8S) a rigid metallo‐capsule was quantitatively formed, which adopts an oblique form owing to the distinct nature of the spacers linking the two calixarene half‐spheres. In the solid state, the 1,4‐substituted phenylene linker is turned towards the gold ion, suggesting the existence of weak bonding interactions between two aromatic CH protons of this ring and the metal centre (Au⋅⋅⋅H=2.67 Å). In contrast to this gold complex, the related silver complex shows dynamic behaviour in solution, the exchange between two enantiomeric oblique forms being facilitated by the greater stereochemical flexibility of AgI vs. AuI. A heteronuclear 109Ag{1H} HMQC experiment established strong correlations between the CH protons of the phenylene linker and the 109Ag ion. Dynamic behaviour similar to that observed for the silver complex was further observed in trans‐[PtCl2⋅L2], a chelate complex that could be obtained quantitatively from L2 and [PtCl2(PhCN)2]. The intended formation of a chelate complex leading to a capsule with an endo‐oriented metal centre was achieved by reacting L3 with [Pd(allyl)(thf)2]BF4. The complex thus formed constitutes the first organometallic transition metal complex embedded in a cavity with large portals. Binding of [RuCl2(p‐cymene)] to L2 and L3 resulted in self‐compacting bimetallic complexes in which each calixarene basket entraps a Ru(p‐cymene) unit, thereby forming molecules occupying a minimal volume.
Exploiting the capabilities of modern GPUs for dense matrix computations
Authors: Barrachina Sergio , Castillo Maribel , Igual Francisco D. , Mayo Rafael , Quintana‐Ortí Enrique S. , Quintana‐Ortí Gregorio 
Published: September 2009

AbstractWe present several algorithms to compute the solution of a linear system of equations on a graphics processor (GPU), as well as general techniques to improve their performance, such as padding and hybrid GPU‐CPU computation. We compare single and double precision performance of a modern GPU with unified architecture, and show how iterative refinement with mixed precision can be used to regain full accuracy in the solution of linear systems, exploiting the potential of the processor for single precision arithmetic. Experimental results on a GTX280 using CUBLAS 2.0, the implementation of BLAS for NVIDIA® GPUs with unified architecture, illustrate the performance of the different algorithms and techniques proposed. Copyright © 2009 John Wiley & Sons, Ltd.
From Peptides to Non‐Peptide Alpha‐Helix Inducers and Mimetics
Authors: Haridas V. 
Published: September 2009

AbstractHelix mimetics are good models for investigating the theories of protein folding and also act as good affinity ligands for therapeutic applications due to their biostability and better blood‐brain barrier crossing ability. The helix mimetics display the same spatial and temporal orientation with respect to the amino acid side‐chains of alpha helix part of the protein, which are involved in protein–protein interactions. The designed nonpeptidic molecules with substituents at the appropriate positions on the scaffold can mimic the amino acid side‐chains of a fully folded alpha helix and can competitively bind with the target protein, thus acting as possible therapeutic agents. This was illustrated with examples like p53/MDM2, CD81/CV E2, Bcl‐xL/Bak, gp‐41, and others, with therapeutic relevance. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Lewis‐Acid‐Catalyzed Reactions of Bis(4‐alkoxyphenyl)methanol with (Diarylmethylene)‐ and (Dialkylmethylene)cyclopropanes
Authors: Yao Liang‐Feng , Shi Min 
Published: September 2009

AbstractBis(4‐methoxyphenyl)methanol (2a) can be transformed by BF3·OEt2‐catalyzed reactions of (arylmethylene)cyclopropanes 1 to the corresponding polysubstituted cyclopentenes 3 as the major products along with methylenecyclobutanes and dienes as minor products. The reaction conditions are mild, yields are moderate to good. In the reactions of aliphatic methylenecyclopropanes with bis(4‐methoxyphenyl)methanol (2a), cyclopentenes 3o–q were produced in good yields under the standard conditions. Interesting results were obtained from the reactions of 1‐[cyclopropylidene(4‐methoxyphenyl)methyl]‐4‐methoxybenzene (1e) with bis(4‐alkoxyphenyl)methanols 2: polysubstituted cyclopentene derivatives 5 were obtained in good yields under mild reaction conditions. Plausible reaction mechanisms based on the deuterium‐labeling and control experiments are proposed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)