bluuebunny/crossref_metadata_2025_split huggingface dataset:
Emulsion copolymerization of styrene and sodium styrene sulfonate: kinetics, monomer reactivity ratios and copolymer properties
Authors: Arunbabu Dhamodaran , Sanga Zomuan , Seenimeera Kamal Mohamed , Jana Tushar 
Published: November 2008

AbstractBACKGROUND: The synthesis of poly[styrene‐co‐(sodium styrene sulfonate)], poly(S‐co‐NaSS), with a high loading of sulfonate groups is of current interest owing to its potential use in numerous areas. A series of these copolymers with various sulfonate loads were synthesized using the emulsion polymerization technique with a study of the copolymerization kinetics, monomer reactivity ratio and copolymer properties.RESULTS: The copolymerization kinetics are significantly enhanced with an increase of NaSS feed in the polymerization. Monomer reactivity ratios were determined from NMR data by employing the Fineman–Ross and Kelen–Tüdös methods. Styrene (r1) and NaSS (r2) reactivity ratios are 0.5 and 10, respectively. The colloidal particle size of the copolymers depends upon the NaSS composition. The thermal stability of the copolymers is greatly enhanced with higher NaSS content in the copolymer backbone. Higher glass transition temperatures are observed for the copolymers with higher NaSS content.CONCLUSION: The reactivity ratio values suggest that styrene prefers to form copolymers whereas NaSS produces homopolymers. It is also found that styrene copolymerization with NaSS is only twice as fast as homopolymerization. In contrast, NaSS homopolymerization is ten times faster than NaSS copolymerization with styrene. The NaSS content in the copolymer backbone affects the thermal stability and the glass transition of the copolymers. Copyright © 2008 Society of Chemical Industry
Poly(hydroxyether of bisphenol A) ‐alt‐polydimethylsiloxane: a novel thermally crosslinkable alternating block copolymer
Authors: Wang Lei , Gong Wei , Zheng Sixun 
Published: November 2008

AbstractBACKGROUND: An important strategy for making polymer materials with combined properties is to prepare block copolymers consisting of well‐defined blocks via facile approaches.RESULTS: Poly(hydroxyether of bisphenol A)‐block‐polydimethylsiloxane alternating block copolymers (PH‐alt‐PDMS) were synthesized via Mannich polycondensation involving phenolic hydroxyl‐terminated poly(hydroxyether of bisphenol A), diaminopropyl‐terminated polydimethylsiloxane and formaldehyde. The polymerization was carried out via the formation of benzoxazine ring linkages between poly(hydroxyether of bisphenol A) and polydimethylsiloxane blocks. Differential scanning calorimetry and small‐angle X‐ray scattering show that the alternating block copolymers are microphase‐separated. Compared to poly(hydroxyether of bisphenol A), the copolymers displayed enhanced surface hydrophobicity (dewettability). In addition, subsequent crosslinking can occur upon heating the copolymers to elevated temperatures owing to the existence of benzoxazine linkages in the microdomains of hard segments.CONCLUSION: PH‐alt‐PDMS alternating block copolymers were successfully obtained. The subsequent self‐crosslinking of the PH‐alt‐PDMS alternating block copolymers could lead to these polymer materials having potential applications. Copyright © 2008 Society of Chemical Industry
Inclusion of ionization states of ligands in affinity calculations
Authors: Donnini Serena , Villa Alessandra , Groenhof Gerrit , Mark Alan E. , Wierenga Rik K. , Juffer André H. 
Published: November 2008

AbstractWhen estimating binding affinities of a ligand, which can exists in multiple forms, for a target molecule, one must consider all possible competing equilibria. Here, a method is presented that estimates the contribution of the protonation equilibria of a ligand in solution to the measured or calculated binding affinity. The method yields a correction to binding constants that are based on the total concentration of inhibitor (the sum of all ionized forms of the inhibitor in solution) to account for the complexed form of the inhibitor only. The method is applied to the calculation of the difference in binding affinity of two inhibitors, 2‐phosphoglycolate (PGA) and its phoshonate analog 3‐phosphonopropionate (3PP), for the glycolytic enzyme triosephosphate isomerase. Both inhibitors have three titrating sites and exist in solution as a mixture of different forms. In this case the form that actually binds to the enzyme is present at relative low concentrations. The contributions of the alternative forms to the difference in binding energies is estimated by means of molecular dynamics simulations and corrections. The inhibitors undergo a pKa shift upon binding that is estimated by ab initio calculations. An interesting finding is that the affinity difference of the two inhibitors is not due to different interactions in the active site of the enzyme, but rather due to the difference in the solvation properties of the inhibitors. Protein 2009. © 2008 Wiley‐Liss, Inc.
Geometric characteristics of hydrogen bonds involving sulfur atoms in proteins
Authors: Zhou Peng , Tian Feifei , Lv Fenglin , Shang Zhicai 
Published: November 2008

AbstractSulfur atoms have been known to participate in hydrogen bonds (H‐bonds) and these sulfur‐containing H‐bonds (SCHBs) are suggested to play important roles in certain biological processes. This study aims to comprehensively characterize all the SCHBs in 500 high‐resolution protein structures (≤1.8 Å). We categorized SCHBs into six types according to donor/acceptor behaviors and used explicit hydrogen approach to distinguish SCHBs from those of nonhydrogen bonding interactions. It is revealed that sulfur atom is a very poor H‐bond acceptor, but a moderately good H‐bond donor. In α‐helix, considerable SCHBs were found between the sulphydryl group of cysteine residue i and the carbonyl oxygen of residue i‐4, and these SCHBs exert effects in stabilizing helices. Although for other SCHBs, they possess no specific secondary structural preference, their geometric characteristics in proteins and in free small compounds are significantly distinct, indicating the protein SCHBs are geometrically distorted. Interestingly, sulfur atom in the disulfide bond tends to form bifurcated H‐bond whereas in cysteine‐cysteine pairs prefer to form dual H‐bond. These special H‐bonds remarkably boost the interaction between H‐bond donor and acceptor. By oxidation/reduction manner, the mutual transformation between the dual H‐bonds and disulfide bonds for cysteine‐cysteine pairs can accurately adjust the structural stability and biological function of proteins in different environments. Furthermore, few loose H‐bonds were observed to form between the sulphydryl groups and aromatic rings, and in these cases the donor H is almost over against the rim rather than the center of the aromatic ring. Proteins 2009. © 2008 Wiley‐Liss, Inc.
Comparisons of experimental and computed protein anisotropic temperature factors
Authors: Yang Lei , Song Guang , Jernigan Robert L. 
Published: November 2008

AbstractBecause of its appealing simplicity, the anisotropic network model (ANM) has been widely accepted and applied to study many molecular motion problems: such as ribosome motions, the molecular mechanisms of GroEL‐GroES function, allosteric changes in hemoglobin, motor‐protein motions, and conformational changes in general. However, the validity of the ANM has not been closely examined. In this work, we use ANM to predict the anisotropic temperature factors of proteins obtained from X‐ray and NMR data. The rich, directional anisotropic temperature factor data available for hundreds of proteins in the protein data bank are used as validation data to closely test the ANM model. The significance of this work is that it presents a timely, important evaluation of the model, shows the extent of its accuracy in reproducing experimental anisotropic temperature factors, and suggests ways to improve the model. An improved model will help us better understand the internal dynamics of proteins, which in turn can greatly expand the usefulness of the models, which has already been demonstrated in many applications. Proteins 2009. © 2008 Wiley‐Liss, Inc.
The dynamics of heat lows over flat terrain
Authors: Spengler Thomas , Smith Roger K. 
Published: November 2008

AbstractThe numerical model for a heat low developed by Rácz and Smith is extended to include a representation of radiative heating and cooling. The model is run with a higher horizontal resolution than the original version and is used to investigate additional dynamical aspects of the structure and evolution of a heat low over a subcontinental‐ or continental‐scale circular island surrounded by sea. Of particular interest is the diurnal and day‐to‐day evolution of the upper‐ and lower‐level circulations and the degree of balance that exists in these. The heat low is surmounted by an anticyclone, the development of which is closely tied to the outflow branch of the sea breeze. The anticyclone has a much smaller diurnal variation than the heat low and, unlike the heat low is largely in balance, except in the region affected by the upward‐propagating gravity wave induced by the inland‐penetrating sea breeze. There is a strong analogy to certain aspects of tropical cyclones, which have a warm core, a shallow unbalanced boundary layer, and which are surmounted also by an anticyclone. Principles governing the absolute angular momentum budget are the same as those relating to the tropical cyclones and to the zonal‐mean flow over Antarctica. Implications of these principles for obtaining a realistic steady state in long‐term integrations of axisymmetric models are discussed. Copyright © 2008 Royal Meteorological Society
Structural Parameter Characterization and Bioactivity Simulation Based on Peptide Sequence
Authors: Shu Mao , Mei Hu , Yang Shanbin , Liao Limin , Li Zhiliang 
Published: November 2008

AbstractIn this paper, a new set of descriptors, Hydrophobic, Electronic, Steric, and Hydrogen (HESH) (principal components scores vectors of the HESH bond contribution properties), were derived from Principal Component Analysis (PCA) on the collected 171 physicochemical properties of 20 coded amino acids. By applying HESH descriptors to Quantitative Structure–Activity Relationship (QSAR) study on three peptides including 58 Angiotensin‐Converting Enzyme (ACE) inhibitors, 48 bitter‐tasting dipeptides, and 20 thromboplastin inhibitors, we get three excellent Partial Least Squares (PLS) models, with the squared multiple correlation coefficients (R$\rm{ _{{\rm{cum}}}^{\rm{2}} }$), cross‐validation (R$\rm{ _{{\rm{cum}}}^{\rm{2}} }$), and Root Mean Square Error (RMSE) of 0.877, 0.838, and 0.361 for ACE inhibitors, 0.926,0.865, and 0.172 for bitter‐tasting dipeptides and 0.996, 0.865, and 0.115 for thromboplastin inhibitors. These results were superior to many other reported researches. It showed that HESH may be a useful structural expression method for the study on QSAR of peptide.
Linear Free Energy Relationship Correlation of The Distribution of Solutes Between Water And Cetytrimethylammonium Bromide (CTAB) Micelles
Authors: Sprunger Laura M. , Gibbs Jennifer , Acree William E. , Abraham Michael H. 
Published: November 2008

AbstractData have been assembled from the published literature on the water‐to‐micellar Cetyltrimethylammonium Bromide (CTAB) partition coefficient data for more than 60 compounds, and on the Micellar Electrokinetic Chromatographic (MEKC) retention factors for more than 50 compounds measured on a CTAB pseudostationary phase. In total more than 200 experimental data have been compiled. The water‐to‐micellar CTAB partition coefficients and MEKC retention factor data from three separate studies have been combined into a single database and correlated with the Abraham model. The derived correlation described the 200 experimental values to within a standard deviation of 0.175 log units. Also, the previously derived Abraham model correlation for water‐to‐micellar Sodium Dodecylsulfate (SDS) was updated to include MEKC retention factor data from the five recent experimental studies. The new repression correlation for SDS is based on 706 experimental values. Principal component analysis showed that water‐to‐micellar surfactant partition systems are good models for non‐polar and polar narcotic toxicities of organic compounds toward fish, water fleas, and other aquatic organisms.
Toward a cross‐layer monitoring process for mobilead hocnetworks
Authors: Rachedi Abderrezak , Benslimane Abderrahim 
Published: November 2008

AbstractThe intrusion detection system (IDS) for mobilead hocnetworks (MANET) consists in monitoring the nodes' behavior, in order to detect the malicious activity of nodes. Many existing solutions deal with the problem at each layer separately. But new kinds of misbehavior attacks are cross‐layer attacks. And such smart misbehaviors cannot be detected at the level of one layer. In this paper, we propose a new cross‐layer approach based on physical, MAC, and routing layers for a monitoring mechanism. A new analytical model is proposed to illustrate the parameters' effect on these different layers. The impact of the signal to noise ratio (SNR) and the distance between monitor and monitored nodes are clearly introduced. Moreover, the difference between the carrier sense, the interference range, and the transmission range is taken into account in our model. The proposed model improves the evaluation of the nodes' cooperation and reduces the risk of having any false positive rate. The analytical study and simulation results illustrate our purpose. In addition, with the simulations' results, we illustrate the impact of the distance between monitor and monitored nodes on the monitoring mechanism. Finally, we show that our cross‐layer mechanism has a lower false positive rate than the classical Watchdog mechanism in different network's parameters such as the nodes' density, the speed mobility, and the different traffic loads. Copyright © 2008 John Wiley & Sons, Ltd.
Integrating fingerprint with cryptosystem for internet‐based live pay‐TV system
Authors: Hou Shuhui , Uehara Tetsutaro , Satoh Takashi , Morimura Yoshitaka , Minoh Michihiko 
Published: November 2008

AbstractIn the last few years, live pay‐TV systemviathe Internet has come to be established with the development of broadband network. To develop such a system, a mechanism for content protection is required. In this paper, a new architecture integrating fingerprint with cryptosystem is proposed to protect digital contents (image and video) from unauthorized viewing and illegal redistribution. Then, a scheme integrating anti‐collusion code and Home Page public‐key cryptosystem (PKC) is described. Such a scheme is shown feasible and realistic for implementing with respect to computation/transmission cost. Copyright © 2008 John Wiley & Sons, Ltd.
Mie and Bragg Plasmons in Subwavelength Silver Semi‐Shells
Authors: Maaroof Abbas I. , Cortie Michael B. , Harris Nadine , Wieczorek Lech 
Published: November 2008

Abstract2D arrays of silver semi‐shells of 100 and 200 nm diameter display complex reflection and transmission spectra in the visible and near‐IR. Here these spectral features are deconstructed and it is demonstrated that they result from the coupling of incident light into a delocalized Bragg plasmon, and the latter's induction of localized Mie plasmons in the arrays. These phenomena permit the excitation of transverse dipolar plasmon resonances in the semi‐shells despite an ostensibly unfavorable orientation with respect to normally incident light. The resulting spectral feature in the mid‐visible is strong and tunable.
Single‐Walled Carbon‐Nanotube Networks on Large‐Area Glass Substrate by the Dip‐Coating Method
Authors: Jang Eui Yun , Kang Tae June , Im Hyeoung Wook , Kim Dae Weon , Kim Yong Hyup 
Published: November 2008

AbstractHighly uniform and large‐area single‐walled carbon‐nanotube (SWNT) networks are realized by the dip‐coating method, which is based on fundamental fluid‐dynamic phenomena such as capillary condensation and surface tension. The changes in the polarity and hydration properties of the substrate affect the morphology of the SWNT networks and result in nonlinear growth of the networks in the repetitive dip‐coating process. The density and the thickness of the SWNT networks are controlled by processing variables including number of dip coatings, concentration of SWNT colloidal solution, and withdrawal velocity. The networks have uniform sheet resistances and high optical transmittance in the visible wavelength range.
Room‐Temperature Synthetic Pathways to Barium Titanate Nanocrystals
Authors: Beier Christopher W. , Cuevas Marie A. , Brutchey Richard L. 
Published: November 2008

AbstractNovel room‐temperature pathways to BaTiO3nanocrystals have been recently developed, which stand in contrast to traditional high‐temperature methods. Peptide‐assisted, bio‐facilitated routes have been developed for low‐temperature nanocrystal growth, in addition to two low‐temperature routes completely independent of biomolecules. These innovative methods lay the groundwork for the facile production of nanoscale BaTiO3in economical and energy‐efficient ways.
Postexposure prophylaxis following sexual exposure to HIV
Authors: Shanmuga Sundaram Sangeetha , Mani Reena 
Published: November 2008

AbstractPostexposure prophylaxis following sexual exposure to HIV should be prescribed on a case‐by‐case basis. The authors explain how to assess the risk from what is known about the source and exposure, and consider the benefits and challenges of this treatment. Copyright © 2008 Wiley Interface Ltd
A randomized study to assess two different techniques of aspiration while performing transabdominal chorionic villus sampling
Authors: Battagliarin G. , Lanna M. , Coviello D. , Tassis B. , Quarenghi A. , Nicolini U. 
Published: November 2008

AbstractObjectiveThe technique used to perform transabdominal chorionic villus sampling (CVS) is not standardized, but aspiration of villi is generally obtained by discontinuous vacuum created in a syringe, manually or by a hand‐grip device. We evaluated the feasibility of a new method of performing CVS which employs a 4‐mL Vacutainer® connected to the needle, producing a continuous negative pressure.MethodsTwo hundred pregnant women, whose gestational age ranged from 10 + 2 to 16 + 2 (mean, 12 + 1) weeks, entered the randomized study, which was powered to detect with 90% probability the absence of any difference in the size of chorionic samples obtained by using a 20‐mL syringe with the vacuum obtained by a hand‐grip device (Group 1) or by a vacutainer (Group 2). Four operators with different levels of experience performed all the procedures, which were done transabdominally using a freehand technique with a 20‐gauge needle under ultrasound guidance.ResultsMaternal age, body mass index, gestational age and the way the needle was inserted within the chorion were similar in the two groups. The median amount of villi sampled was 20 mg, with no differences between the two groups. The rate of fetal loss was 1.7%. All losses occurred in women of Group 1 who had only one needle insertion. A second needle insertion was required more frequently while using the vacutainer.ConclusionThis new technique for performing transabdominal CVS uses a readily available device and is as effective as traditional sampling systems to aspirate villi. It has the advantage of being a one‐operator procedure. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Reactivity of [(Ph2Si)2O3]4[Al(OH)]4 and [(Ph2Si)2O3]4[Al(OLi)]4 towards NaOEt and LiOH. Synthesis of New Twelve‐membered Alumopolysiloxane Rings
Authors: Veith Michael , Smail Hakima , Huch Volker 
Published: November 2008

AbstractThe reaction between [(Ph2Si)2O3]4[Al(OH)]4 (1) or [(Ph2Si)2O3]4[Al(OLi)]4 (2) with sodium ethoxide, or lithium hydroxide in presence of CuI·H2O leads to the formation of new alumopolysiloxane compounds. Indeed, transformations of 1 under the partial incorporation of the reactants are found giving rise to new heteroleptic inorganic macrocycles. The molecular structure of [(Ph2Si)2O3]4[Al(ONa)]2[Al(OH)(NaOEt)]2·2Et2O (3) and [(Ph2Si)2O3]4[Al(OLi)]2[Al(OH)(LiOH)]2·2Et2O·2THF (4) have been determined by single‐X‐ray diffraction analysis. Both alumosiloxanes 3 and 4 are constituted by a twelve‐membered ring.
Three New Thioantimonates(V): Solvothermal Syntheses and Crystal Structures of [M(chxn)3]3(SbS4)2·4H2O (M = Ni, Co) and [Co(dien)2][Co(tren)SbS4]2·4H2O
Authors: Engelke Lars , Näther Christian , Leisner Phillipp , Bensch Wolfgang 
Published: November 2008

AbstractThe three new thioantimonates(V) [Ni(chxn)3]3(SbS4)2·4H2O (I), [Co(chxn)3]3(SbS4)2·4H2O (II) (chxn is trans‐1,2‐diaminocyclohexane) and [Co(dien)2][Co(tren)SbS4]2·4H2O (III) (dien is diethylenetriamine and tren is tris(2‐aminoethyl)amine) were synthesized under solvothermal conditions. Compounds I and II are isostructural crystallizing in space group C2/c. The structures are composed of isolated [M(chxn)3]2+ complexes (M = Ni, Co), [SbS4]3− anions and crystal water molecules. Short S···N/S···O/O···O separations indicate hydrogen bonding interactions between the different constituents. Compound III crystallizes in space group $P{\bar 1}$ and is composed of [Co(dien)2]2+ and [Co(tren)SbS4]− anions and crystal water molecules. In the cationic complex the Co2+ ion is in an octahedral environment of two dien ligands whereas in [Co(tren)SbS4]− the Co2+ ion is in a trigonal bipyramidal coordination of four N atoms of tren and one S atom of the [SbS4]3− anion, i.e., two different coordination polyhedra around Co2+ coexist in this compound. Like in the former compounds an extended hydrogen bonding network connects the complexes and the water molecules into a three‐dimensional network.
Process algebraic modelling of attentional capture and human electrophysiology in interactive systems
Authors: Su Li , Bowman Howard , Barnard Philip , Wyble Brad 
Published: November 2008

AbstractPrevious research has developed a formal methods-based (cognitive-level) model of the Interacting Cognitive Subsystems central engine, with which we have simulated attentional capture in the context of Barnard’s key-distractor Attentional Blink task. This model captures core aspects of the allocation of human attention over time and as such should be applicable across a range of practical settings when human attentional limitations come into play. In addition, this model simulates human electrophysiological data, such as electroencephalogram recordings, which can be compared to real electrophysiological data recorded from human participants. We have used this model to evaluate the performance trade-offs that would arise from varying key parameters and applying either a constructive or a reactive approach to improving interactive systems in a stimulus rich environment. A strength of formal methods is that they are abstract and the resulting specifications of the operator are general purpose, ensuring that our findings are broadly applicable. Thus, we argue that new modelling techniques from computer science can also be employed in computational modelling of the mind. These would complement existing techniques, being specifically targeted at psychological level modelling, in which it is advantageous to directly represent the distribution of control.