bluuebunny/crossref_metadata_2025 huggingface dataset:
Negotiating interests or values and reaching integrative agreements: the importance of time pressure and temporary impasses
Authors: Harinck Fieke , De Dreu Carsten K. W.
Published: August 2004

Negotiation research and theory tends to focus on interests and ignores values. This experiment compared the influence of negotiations about interests with negotiations about values under low or high time pressure. Results showed that (1) individuals got locked into early impasses more often under low than high time pressure, (2) getting locked into early impasse produced a switch from low levels of integrative behaviour early in the negotiation to high levels late in the negotiation, but only when interests rather than values were negotiated, (3) individuals reached higher joint outcomes when interests rather than values were negotiated, especially when time pressure was low rather than high, because of (4) the relatively greater switch to high levels of integrative behaviour in the case of low time pressure and conflict of interest. Copyright © 2004 John Wiley & Sons, Ltd.
Homogeneity perception as a reaction to identity threat: effects of status difference in a simulated society game
Authors: Karasawa Minoru , Karasawa Kaori , Hirose Yukio
Published: August 2004

The present study examined how members of low status groups would react to a threat to their social identity. Undergraduates participated in a ‘simulated society game,’ and were divided into four groups, each of which was assigned either a high or low status. During a series of game sessions with intergroup competition and cooperation, participants estimated the range of distributions among in‐ group and out‐group members regarding various traits. The central tendency and variability derived from each estimate were analysed. Members of the low status groups deprecated their in‐group with respect to a status‐defining trait, but showed in‐group favouritism regarding alternative, status‐irrelevant traits. Furthermore, the low status members judged their in‐group as more homogeneous than the out‐group regarding the alternative traits, particularly when they were compared to a high status group. The results were interpreted as an indication of a subtle form of maintaining positive in‐group evaluations. Theoretical and methodological implications for the study of status effects are discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Motivational influence on the quality of memories: recall of general autobiographical memories related to desired attributes
Authors: Brunot Sophie , Sanitioso Rasyid Bo
Published: August 2004

This article concerns recall of general autobiographical memories in motivated self‐perception. General memories, comprising abstraction of repeated or similar behaviours, have more impact on how one defines oneself than do specific memories. In a study, participants were first induced to believe that either extraversion or introversion leads to success. In the recall task that followed, introversion‐success participants recalled more general memories related to introversion than did extraversion‐success participants. In contrast, extraversion‐success participants recalled more general extraverted memories than did introversion‐success participants. Thus, to preserve a positive self‐image as characterized by desirable attributes, recall may be directed towards generation of general memories related to the attributes. Copyright © 2004 John Wiley & Sons, Ltd.
The representation of majorities and minorities in the British press: a content analytic approach
Authors: Gardikiotis Antonis , Martin Robin , Hewstone Miles
Published: August 2004

A content analysis examined the way majorities and minorities are represented in the British press. An analysis of the headlines of five British newspapers, over a period of five years, revealed that the words ‘majority’ and ‘minority’ appeared 658 times. Majority headlines were most frequent (66% ), more likely to emphasize the numerical size of the majority, to link majority status with political groups, to be described with positive evaluations, and to cover political issues. By contrast, minority headlines were less frequent (34%), more likely to link minority status with ethnic groups and to other social issues, and less likely to be described with positive evaluations. The implications of examining how real‐life majorities and minorities are represented for our understanding of experimental research are discussed. Copyright © 2004 John Wiley & Sons, Ltd.
High‐order boundary conditions for linearized shallow water equations with stratification, dispersion and advection
Authors: van Joolen Vince J. , Neta Beny , Givoli Dan
Published: August 2004

The two‐dimensional linearized shallow water equations are considered in unbounded domains with density stratification. Wave dispersion and advection effects are also taken into account. The infinite domain is truncated via a rectangular artificial boundary ℬ︁, and a high‐order open boundary condition (OBC) is imposed on ℬ︁. Then the problem is solved numerically in the finite domain bounded by ℬ︁. A recently developed boundary scheme is employed, which is based on a reformulation of the sequence of OBCs originally proposed by Higdon. The OBCs can easily be used up to any desired order. They are incorporated here in a finite difference scheme. Numerical examples are used to demonstrate the performance and advantages of the computational method, with an emphasis is on the effect of stratification. Published in 2004 by John Wiley & Sons, Ltd.
Passive control of the flow around a square cylinder using porous media
Authors: Bruneau Charles‐Henri , Mortazavi Iraj
Published: August 2004

The passive control of bluff body flows using porous media is investigated by means of the penalization method. This method is used to create intermediate porous media between solid obstacles and the fluid in order to modify the boundary layer behaviour. The study covers a wide range of two‐dimensional flows from low transitional flow to fully established turbulence by direct numerical simulation of incompressible Navier–Stokes equations. A parametric study is performed to illustrate the effect of the porous layer permeability and thickness on the passive control. The numerical results reveal the ability of porous media to both regularize the flow and to reduce the drag forces up to 30%. Copyright © 2004 John Wiley & Sons, Ltd.
Free boundary viscous flows at micro and mesolevel during liquid composites moulding process
Authors: Dimitrovová Zuzana , Advani Suresh G.
Published: August 2004

Numerical simulation aspects, related to low Reynolds number free boundary viscous flows at micro and mesolevel during the resin impregnation stage of the liquid composite moulding process (LCM), are presented in this article. A free boundary program (FBP), developed by the authors, is used to track the movement of the resin front accurately by accounting for the surface tension effects at the boundary. Issues related to the global and local mass conservation (GMC and LMC) are identified and discussed. Unsuitable conditions for LMC and consequently GMC are uncovered at low capillary numbers, and hence a strategy for the numerical simulation of such flows is suggested.

FBP encompasses a set of subroutines that are linked to modules in ANSYS. FBP can capture the void formation dynamics based on the analysis developed. We present resin impregnation dynamics in two dimensions. Extension to three dimensions is a subject for further research. Several examples are shown and efficiency of different stabilization techniques are compared. Copyright © 2004 John Wiley & Sons, Ltd.
Non‐oscillatory relaxation methods for the shallow‐water equations in one and two space dimensions
Authors: Seaïd Mohammed
Published: August 2004

In this paper, a new family of high‐order relaxation methods is constructed. These methods combine general higher‐order reconstruction for spatial discretization and higher order implicit‐explicit schemes or TVD Runge–Kutta schemes for time integration of relaxing systems. The new methods retain all the attractive features of classical relaxation schemes such as neither Riemann solvers nor characteristic decomposition are needed. Numerical experiments with the shallow‐water equations in both one and two space dimensions on flat and non‐flat topography demonstrate the high resolution and the ability of our relaxation schemes to better resolve the solution in the presence of shocks and dry areas without using either Riemann solvers or front tracking techniques. Copyright © 2004 John Wiley & Sons, Ltd.
A new algorithm to handle finite nuclear mass effects in electronic calculations: The ISOTOPE program
Authors: Gonçalves Cristina P. , Mohallem José R.
Published: August 2004

We report the development of a simple algorithm to modify quantum chemistry codes based on the LCAO procedure, to account for the isotope problem in electronic structure calculations. No extra computations are required compared to standard Born–Oppenheimer calculations. An upgrade of the Gamess package called ISOTOPE is presented, and its applicability is demonstrated in some examples. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1736–1739, 2004
Ab initio and DFT studies on hydrolyses of phosphorus halides
Authors: Lee Oh‐Seuk , Yang Kiyull , Kang Keum Duck , Koo In Sun , Kim Chan‐Kyung , Lee Ikchoon
Published: August 2004

Hydrolyses of phosphorus halides, (RO)2POX where R = H or Me and X = F or Cl, in the gas phase and in the reaction field have been investigated theoretically with ab initio and the density functional theory (DFT). The free energy of activation in the reaction field was also estimated using the Onsager method with a correction of entropy change and basis set superposition error (BSSE). The reaction of (MeO)2POF proceeds through a path with bifunctional catalysis regardless of the medium, but the reaction of (MeO)2POCl proceeds through bifunctional and general base catalysis in the gas phase and in water, respectively. The estimated free energy barrier of 23 kcal/mol for the hydrolysis of (MeO)2POF is in good agreement with the experimental values of 24 kcal/mol, and relative barrier of 3 kcal/mol to the (MeO)2POCl is also in good agreement with the experimental values of 5 kcal/mol of diisopropyl phosphorus halides ((PriO)2POX, X = F and Cl). © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1740–1748, 2004
Asymptotic results on the existence of 4‐RGDDs and uniform 5‐GDDs
Authors: Ge Gennian , Ling Alan C. H.
Published: August 2004

In this paper, we continue to investigate the existence of 4‐RGDDs and uniform 5‐GDDs. It is proved that the necessary conditions for the existence of such designs are also sufficient with a finite number of possible exceptions. As an application, the known results on the existence of uniform 4‐frames are also improved. © 2004 Wiley Periodicals, Inc.
α‐Resolvable group divisible designs with block size three
Authors: Zhang Yan , Du Beiliang
Published: August 2004

A group divisible design GD(k,λ,t;tu) is α‐resolvable if its blocks can be partitioned into classes such that each point of the design occurs in precisely α blocks in each class. The necessary conditions for the existence of such a design are λt(u − 1) = r(k − 1), bk = rtu, k|αtu and α|r. It is shown in this paper that these conditions are also sufficient when k = 3, with some definite exceptions. © 2004 Wiley Periodicals, Inc.
Some new results on superimposed codes
Authors: Kim Hyun Kwang , Lebedev Vladimir , Oh Dong Yeol
Published: August 2004

A (w,r) cover‐free family is a family of subsets of a finite set such that no intersection of w members of the family is covered by a union of r others. A (w,r) superimposed code is the incidence matrix of such a family. Such a family also arises in cryptography as the concept of key distribution pattern. In the present paper, we give some new results on superimposed codes. First we construct superimposed codes from super‐simple designs which give us results better than superimposed codes constructed by other known methods. Next we prove the uniqueness of the (1,2) superimposed code of size 9 × 12, the (2,2) superimposed code of size 14 × 8, and the (2,3) superimposed code of size 30 × 10. Finally, we improve numerical values of upper bounds for the asymptotic rate of some (w,r) superimposed codes. © 2004 Wiley Periodicals, Inc.
Morphology, structure of dimorphic sperm, and reproduction in the hermaphroditic commensal bivalve Pseudopythina tsurumaru (Galeommatoidea: Kellidae)
Authors: Lützen Jørgen , Jespersen Åse , Takahashi Tohru , Kai Takayuki
Published: August 2004

In Japan Pseudopythina tsurumaru is an up to 10.8 mm‐long commensal of the burrowing sea cucumber Protankyra bidentata, whereas in Hong Kong the same species is smaller and associated with the crab Hexapus anfractus, itself a commensal of P. bidentata. Japanese P. tsurumaru is a hermaphrodite tending towards protogyny maturing to a female when ≥7 mm, and entering the hermaphroditic condition when ≥9 mm long. In addition to normal euspermatozoa, the species produces 30–32 μm long and 7 × 8 μm broad spindle‐shaped paraspermatozoa provided with a conical acrosome, a nucleus, and a bundle of ∼15–16 flagella issuing from the head region. Paired pouch‐formed seminal receptacles normally occur in bivalves ≥6 mm. Bulk sperm transfer presumably takes place by way of spermatozeugmata formed by the two types of sperm cells. Exogenous euspermatozoa attach to particular nonepithelial cells that occupy the interior of the receptacles. These cells, together with their associated sperm, are probably released as syncytial sperm‐carrying bodies into the suprabranchial chamber, where the ova are fertilized. J. Morphol. 262:407–420, 2004. © 2004 Wiley‐Liss, Inc.
Biomechanical modeling and sensitivity analysis of bipedal running ability. II. Extinct taxa
Authors: Hutchinson John R.
Published: August 2004

Using an inverse dynamics biomechanical analysis that was previously validated for extant bipeds, I calculated the minimum amount of actively contracting hindlimb extensor muscle that would have been needed for rapid bipedal running in several extinct dinosaur taxa. I analyzed models of nine theropod dinosaurs (including birds) covering over five orders of magnitude in size. My results uphold previous findings that large theropods such as Tyrannosaurus could not run very quickly, whereas smaller theropods (including some extinct birds) were adept runners. Furthermore, my results strengthen the contention that many nonavian theropods, especially larger individuals, used fairly upright limb orientations, which would have reduced required muscular force, and hence muscle mass. Additional sensitivity analysis of muscle fascicle lengths, moment arms, and limb orientation supports these conclusions and points out directions for future research on the musculoskeletal limits on running ability. Although ankle extensor muscle support is shown to have been important for all taxa, the ability of hip extensor muscles to support the body appears to be a crucial limit for running capacity in larger taxa. I discuss what speeds were possible for different theropod dinosaurs, and how running ability evolved in an inverse relationship to body size in archosaurs. J. Morphol. 262:441–461, 2004. © 2004 Wiley‐Liss, Inc.
Anatomy and functional morphology of the feeding apparatus of the lesser electric ray, Narcine brasiliensis (Elasmobranchii: Batoidea)
Authors: Dean Mason N. , Motta Philip J.
Published: August 2004

Protrusion of the jaws during feeding is common in Batoidea (rays, skates, sawfishes, and guitarfishes), members of which possess a highly modified jaw suspension. The lesser electric ray, Narcine brasiliensis, preys primarily on polychaete annelids using a peculiar and highly derived mechanism for jaw protraction. The ray captures its prey by protruding its jaws beneath the substrate and generating subambient buccal pressure to suck worms into its mouth. Initiation of this protrusion is similar to that proposed for other batoids, in that the swing of the distal ends of the hyomandibulae is transmitted to Meckel's cartilage. A “scissor‐jack” model of jaw protrusion is proposed for Narcine, in which the coupling of the upper and lower jaws, and extremely flexible symphyses, allow medial compression of the entire jaw complex. This results in a shortening of the distance between the right and left sides of the jaw arch and ventral extension of the jaws. Motion of the skeletal elements involved in this extreme jaw protrusion is convergent with that described for the wobbegong shark, Orectolobus maculatus. Narcine also exhibits asymmetrical protrusion of the jaws from the midline during processing, accomplished by unequal depression of the hyomandibulae. Lower jaw versatility is a functional motif in the batoid feeding mechanism. The pronounced jaw kinesis of N. brasiliensis is partly a function of common batoid characteristics: euhyostylic jaw suspension (decoupling the jaws from the hyoid arch) and complex and subdivided cranial musculature, affording fine motor control. However, this mechanism would not be possible without the loss of the basihyal in narcinid electric rays. The highly protrusible jaw of N. brasiliensis is a versatile and maneuverable feeding apparatus well‐suited for the animal's benthic feeding lifestyle. J. Morphol. 262:462–483, 2004. © 2004 Wiley‐Liss, Inc.
Spermiogenesis in caecilians Ichthyophis tricolor and Uraeotyphlus cf. narayani (Amphibia: Gymnophiona): Analysis by light and transmission electron microscopy
Authors: Smita Mathew , George Jancy M. , Girija R. , Akbarsha M.A. , Oommen Oommen V.
Published: August 2004

Spermiogenesis, known as spermateleosis in lower vertebrates, is the transformation of the round spermatid into a highly specialized spermatozoon with a species‐specific structure. Spermateleosis and sperm morphology of two species of caecilians, Ichthyophis tricolor and Uraeotyphlus cf. narayani, from the Western Ghats of Kerala, India, were studied using light and transmission electron microscopy. Spermateleosis is described in early, mid‐, and late phases. During the early phase, the spermatid nucleus does not elongate, but the acrosome vesicle is Golgi‐derived and its material is produced as a homogeneous substance rather than as discrete granules. In development of the acrosome, the centrioles shift in position to the lower half of the cell. The acrosomal vesicles take the full shape of the acrosome with the establishment of the perforatorium in midphase. An endonuclear canal develops and accommodates the perforatorium. The incipient flagellum is laid down when the proximal centriole attaches to the posterior side of the nucleus and the distal centriole connects to the proximal centriole, which forms the basal granule of the acrosome. The axial fiber also appears during midphase. The mitochondria shift in position to the posterior pole of the cell to commence establishment of the midphase. Late phase is characterized by nuclear condensation and elongation. Consequently, the final organization of the sperm is established with the head containing the nucleus and the acrosome. The undulating membrane separates the axoneme and axial fiber. Most of the cytoplasm is lost as residual bodies. J. Morphol. 262:484–499, 2004. © 2004 Wiley‐Liss, Inc.
Comparative anatomy of the superfamily Myliobatoidea (Chondrichthyes) with some comments on phylogeny
Authors: González‐Isáis Mónica , Domínguez Héctor Marcos Montes
Published: August 2004

The anatomy of species belonging to the superfamily Myliobatoidea was examined with the aim of better determining their phylogenetic relationships. A wide variation among genera was observed in skeletal anatomy, despite the fact that they all share a common morphological pattern. However, variation among species of the same genus was low, excepting Mobula. Dorsal musculature showed a substantial consistency, except for the epiaxialis muscle, which was larger in rhinopterids and mobulids. Variation in the ventral muscles was low among species of the same genus, but considerable among different genera. Mobulids have a reduction in ventral muscles, while rhinopterids and myliobatoids show an increase in muscular mass. A consensus tree shows a basal split into two groups. The first includes the family Gymnuridae with the genera Gymnura and Aetoplatea; this group is supported by seven synapomorphies, including: 27(1) ceratobranchialis fused proximally, 36(1) anterior lateral processes present in the synarcual, 52(0) quadratomandibularis internal muscle present. The second group is composed of the family Myliobatidae (Myliobatis, Aetomylaeus, Aetobatus, Rhinoptera, Mobula, and Manta), this group is supported by 11 synapomorphies, including: 5(1) first postorbital process fused with the second, 21(1) fused mandibular symphysis, 24(1) first hypobranchial cartilage absent, 48(2) epiaxialis muscle inserted in the cranial orbital region, 73(1) pectoral fins joined behind the orbital region. This study concluded that myliobatoids (Myliobatis, Aetomylaeus, and Aetobatus) integrate a monophyletic group which, unlike other phylogenies previously obtained, is the sister group of rhinopterids (Rhinoptera). Mobulids (Mobula and Manta) are the sister group of myliobatoids‐rhinopterids. J. Morphol. 262:517–535, 2004. © 2004 Wiley‐Liss, Inc.
Changes in oviductal morphology of the skink, Lampropholis guichenoti, associated with egg production
Authors: Adams S.M. , Hosie M.J. , Murphy C.R. , Thompson M.B.
Published: August 2004

We describe changes in the morphology of the oviductal epithelium of an oviparous skink, Lampropholis guichenoti, during the course of egg production and oviposition : to characterize the luminal epithelial changes; to provide a baseline for understanding uterine changes in viviparous species; and to establish whether the plasma membrane transformation of uterine epithelial cells is indeed a feature restricted to viviparous species. Oviducts from vitellogenic, gravid, and postgravid females were observed using scanning electron microscopy. Cellular characteristics of the oviductal epithelium previously used to determine the plasma membrane transformation were assessed morphologically. Three anatomically different areas were defined within the oviduct, but no plasma membrane transformation was observed in the oviparous skink, suggesting that this is a phenomenon particular to viviparity. J. Morphol. 262:536–544, 2004. © 2004 Wiley‐Liss, Inc.
Fractionation and characterisation for antioxidant activity of hydrolysed whey protein
Authors: Peña‐Ramos E Aida , Xiong Youling L , Arteaga Guillermo E
Published: August 2004

Whey protein isolate (WPI) was hydrolysed for 1 h using Alcalase, Protamex and Flavourzyme. Native WPI, hydrolysed WPI and two commercial WPI hydrolysates were subjected to fractionation by size exclusion chromatography. Antioxidant activity of WPI fractions was measured with a liposome‐oxidising system (50 µM FeCl3/0.1 µM ascorbate, pH 7.0). Lipid oxidation was measured as thiobarbituric acid‐reactive substances (TBARS). Gel electrophoresis and amino acid analysis were run to identify the peptide composition. The influence of amino acid composition on antioxidant activity was evaluated using multivariate analysis methods (correlation analysis, principal component analysis, multiple linear regression and discriminant analysis). TBARS assays indicated the presence of antioxidant activity in all protein fractions, including non‐hydrolysed WPI. For native and hydrolysed WPI samples the first fraction (> 45 kDa) showed a higher TBARS inhibition effect (24–27%) when compared with lower‐molecular‐weight fractions and hydrolysate mixtures. In contrast, for commercial WPI hydrolysates a higher inhibitory effect was found in most of the lower‐molecular‐weight fractions (30–55%). The ability of WPI fractions to delay lipid oxidation was found to be related to the prevalence of histidine and hydrophobic amino acids. Copyright © 2004 Society of Chemical Industry
Compression of Polymer Brushes Under a Lateral Force
Authors: Amoskov Victor M. , Birshtein Tatiana M. , Darinskii Anatoly A. , Tupitsyna Alla I.
Published: August 2004

Summary: The influence of a lateral force (or lateral shear) acting on chains in a polymer brush is investigated theoretically. Brushes consisting of chains with temperature dependent anisotropic interactions between monomers (main‐chain mesogenic groups) are considered. It is shown that a lateral force applied to polymer brush induces its compression. In contrast to a conventional brush, the compression of brush, capable of forming a liquid crystalline (LC) state, can be caused by comparatively small shear forces. Moreover, such shear forces can induce a phase transition of a brush into the tilted LC state with a several‐fold decrease in brush thickness. These results allow us to predict a possibility to observe a decrease in brush thickness in a real experiment with reasonably values of shear rate.

Model of a chain in a polymer brush under an influence of lateral force p.

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Model of a chain in a polymer brush under an influence of lateral force p.
QT prolongation through hERG K+ channel blockade: Current knowledge and strategies for the early prediction during drug development
Authors: Recanatini Maurizio , Poluzzi Elisabetta , Masetti Matteo , Cavalli Andrea , De Ponti Fabrizio
Published: August 2004

Prolongation of the QT interval of the electrocardiogram is a typical effect of Class III antiarrhythmic drugs, achieved through blockade of potassium channels. In the past decade, evidence has accrued that several classes of drugs used for non‐cardiovascular indications may prolong the QT interval with the same mechanism (namely, human ether‐à‐go‐go‐related gene (hERG) K+ channel blockade). The great interest in QT prolongation is because of several reasons. First, drug‐induced QT prolongation increases the likelihood of a polymorphous ventricular arrhythmia (namely, torsades de pointes, TdP), which may cause syncope and degenerate into ventricular fibrillation and sudden death. Second, the fact that several classes of drugs, such as antihistamines, fluoroquinolones, macrolides, and neuroleptics may cause the long QT syndrome (LQTS) raises the question whether this is a class effect (e.g., shared by all agents of a given pharmacological class) or a specific effect of single agents within a class. There is now consensus that, in most cases, only a few agents within a therapeutic class share the ability to significantly affect hERG K+ channels. These compounds should be identified as early as possible during drug development. Third, QT prolongation and interaction with hERG K+ channels have become surrogate markers of cardiotoxicity and have received increasing regulatory attention. This review briefly outlines the mechanisms leading to QT prolongation and the different strategies that can be followed to predict this unwanted effect. In particular, it will focus on the approaches recently proposed for the in silico screening of new compounds. © 2004 Wiley Periodicals, Inc.
DFT and NMR parameterized conformation of valeranone
Authors: Torres‐Valencia J. Martín , Meléndez‐Rodríguez Myriam , Álvarez‐García Rocío , Cerda‐García‐Rojas Carlos M. , Joseph‐Nathan Pedro
Published: August 2004

A Monte Carlo random search using molecular mechanics, followed by geometry optimization of each minimum energy structure employing density functional theory (DFT) calculations at the B3LYP/6–31G* level and a Boltzmann analysis of the total energies, generated accurate molecular models which describe the conformational behavior of the antispasmodic bicyclic sesquiterpene valeranone (1). The theoretical HCCH dihedral angles gave the corresponding 1H, 1H vicinal coupling constants using a generalized Karplus‐type equation. In turn, the 3J(H,H) values were used as initial input data for the spectral simulation of 1, which after iteration provided an excellent correlation with the experimental 1H NMR spectrum. The calculated 3J(H,H) values closely predicted the experimental values, excepting the coupling constant between the axial hydrogen α to the carbonyl group and the equatorial hydrogen β to the carbonyl group (J2β, 3β). The difference is explained in terms of the electron density distribution found in the highest occupied molecular orbital (HOMO) of 1. The simulated spectrum, together with 2D NMR experiments, allowed the total assignment of the 1H and 13C NMR spectra of 1. Copyright © 2004 John Wiley & Sons, Ltd.
Conformational and substituent effects in the 19F spectra of C7–C10 straight‐chain chlorofluoroalkanes
Authors: Brey Wallace S. , West John
Published: August 2004

One‐ and two‐dimensional fluorine NMR spectra of straight‐chain chlorofluoroalkanes having 7–10 carbons were obtained and interpreted. Spectral assignments were based primarily on indirect spin–spin correlations. A scale of chlorine substituent effects was developed. The effects of asymmetric CFCl centers on chemical‐shift differences in nearby CF2 groups were analyzed in terms of molecular conformational effects. Spin–spin coupling patterns of CF3 groups were elucidated. Copyright © 2004 John Wiley & Sons, Ltd.
Eudesm‐5‐en‐11‐ol from Helichrysum italicum essential oil
Authors: Bianchini Ange , Tomi Félix , Richomme Pascal , Bernardini Antoine‐François , Casanova Joseph
Published: August 2004

Eudesm‐5‐en‐11‐ol was isolated from the oil of Helichrysum italicum and its structure was elucidated by 1D and 2D NMR spectroscopy. Copyright © 2004 John Wiley & Sons, Ltd.
Measurement of long‐range 29Si,13C spin–spin coupling at natural abundance
Authors: Blechta Vratislav , Sýkora Jan , Schraml Jan
Published: August 2004

Schemes for sensitive measurements of spin–spin coupling constants between rare nuclei with low magnetogyric ratios are considered and two combinations of INEPT with gradient versions of (X,Y)HMQC and (X,Y)COSY are suggested as particularly suitable for 29Si,13C couplings. It is demonstrated that the (H,Si)INEPT–(Si,C,Si)gHMQC combination (with 29Si detection) produces excellent results even though it is theoretically inferior to the (H,Si)INEPT–(Si,C)gCOSY combination (with 13C detection). Copyright © 2004 John Wiley & Sons, Ltd.
Structure determination of a sildenafil analogue contained in commercial herb drinks
Authors: Shin Choonshik , Hong Mooki , Kim Daibyung , Lim Yoongho
Published: August 2004

It was found from HPLC analysis that a commercial herb drink contains a putative sildenafil analog. In order to identify the sildenafil‐like compound, separation and purification were carried out. The structure determination was performed based on routine 1D and 2D NMR experiments. Unlike sildenafil, the compound contains an ethylpiperazine instead of a methylpiperazine group. In addition, the piperazine and phenyl groups are connected through an acetyl group instead of the sulfonyl group of sildenafil. Copyright © 2004 John Wiley & Sons, Ltd.
NMR spectroscopic analysis of neferine and isoliensinine
Authors: Yang Jian , Zhou Kailan
Published: August 2004

Neferine and isoliensinine are the two major compositions of the Chinese medicine lotus plumule. They have extensive cardiovascular activity, such as antiarrhythmic, antithrombic and antihypertensive. In order to confirm the structures reported in the literature by explicit 1H and 13C assignments, we used a series of NMR experiments including 1H, 1H‐COSY, HSQC and HMBC. The absolute configuration of neferine (C‐1 and C‐1′) was determined as R and S and that of isoliensinine (C‐1 and C‐1′) was determined as R and R. Copyright © 2004 John Wiley & Sons, Ltd.
Studies on epoxy resins cured by cationic latent thermal catalyst at elevated temperature
Authors: Park Soo‐Jin , Seo Min‐Kang , Lee Jae‐Rock
Published: August 2004

In this work, the effect of the catalyst content was investigated in terms of the thermal and mechanical properties of epoxy resins at elevated temperature. A synthesized cationic latent thermal catalyst, N‐benzylpyrazinium hexafluoroantimonate (BPH), was used to cure epoxy resins. The content of catalyst added was 0.5, 1, 2, 3 and 5 wt% and the heating time was varied from 0 to 1024 h. As a result, the mechanical properties, including flexural strength, elastic modulus in flexure and impact strength, as well as thermal‐oxidative resistance, showed a maximum value in the presence of 1 wt% BPH. With increasing elapsed time, up to 4 h, the thermal and mechanical properties of the specimens were improved. These results show that the internal structure of the epoxy system was stabilized, and post‐curing for a longer period of time, resulted in improved thermal and mechanical behaviour of the cast specimens. Copyright © 2004 Society of Chemical Industry
Kinetic study of the synthesis of a methacrylic ester copolymer by nuclear magnetic resonance
Authors: Alvares Dellyo RS , Menezes Sônia MC , Lucas Elizabete F
Published: August 2004

Methacrylic ester copolymers were synthesized in various compositions with the aim of studying the kinetics of the copolymerization reaction. Nuclear magnetic resonance was used not only to investigate the kinetic behavior but also to monitor the reaction course. Copolymers were synthesized in the NMR tube allowing data acquisition in real time. Reactivity ratios for methyl methacrylate and octadecyl methacrylate were obtained. Copyright © 2004 Society of Chemical Industry
Toughening mechanism in polyoxymethylene/thermoplastic polyurethane blends
Authors: Gao Xiaoling , Qu Cheng , Fu Qiang
Published: August 2004

In order to better understand the toughening mechanism in polyoxymethylene (POM)/thermoplastic polyurethane (TPU) blends and obtain ‘super‐toughened’ POM, we carried out an investigation on the notched impact strength, fractured surface, inter‐particle distance and spherulite size of POM as a function of the TPU content. A compatibilizer, namely polystyrene‐block‐poly(ethylene–butylene)‐block‐polystyrene, grafted with maleic anhydride (SEBS‐graft‐MA), was used to enhance the interfacial interaction between the POM and TPU. The impact strength is found to increase in two steps as a function of TPU content, namely a linear increase at the very beginning, and then a jump of impact strength is seen when the TPU content is larger than 30 wt%. A ‘supertough behavior’ is not observed for POM/TPU blends at room temperature, but can be achieved after adding 5 wt% of SEBS‐graft‐MA as the compatibilizer. The impact strength was found to depend not only on the interparticle distance but also on the interfacial interactions between POM and TPU. The dependence of impact strength on crystal size is considered for the first time, and a single curve is constructed, regardless of the composition and interfacial interactions. Our results indicate that the crystal size of POM indeed plays a role in determining the toughness, and has to be considered when discussing the toughening mechanism. Copyright © 2004 Society of Chemical Industry
Miscibility of DMPC‐TMPC copolycarbonate/SMMA copolymer blends and their interaction energies of binary pairs involved in blends
Authors: Yoo JE , Kim CK
Published: August 2004

The isothermal miscibility map and phase‐separation temperatures caused by lower critical solution temperature‐type phase behavior for blends of poly[2,2,‐propane‐bis{4‐(2‐methyl phenyl)} carbonate]‐poly[2,2,‐propane‐bis{4‐(2,6‐dimethyl phenyl)} carbonate] (DMPC‐TMPC) with poly[(styrene)‐co‐(methyl methacrylate)] (SMMA) copolymers have been determined. SMMA copolymers containing equal to or less than 37 wt% MMA formed miscible blends with DMPC‐TMPC copolycarbonates containing equal to or more than 60 wt% TMPC. The observed phase‐separation temperatures indicate that the miscibility decreases as the DMPC content in DMPC‐TMPC increases, while addition of MMA to the styrene initially increases miscibility with DMPC‐TMPC but ultimately leads to immiscibility. The binary interaction energies involved in these blends were calculated from the phase boundaries using the lattice‐fluid theory combined with the binary interaction model. The spinodal temperatures predicted from the lattice‐fluid theory using the calculated interaction energies are similar to the experimental phase‐separation temperatures. Copyright © 2004 Society of Chemical Industry
Moisture sorption and permeation in polyamide 6/clay nanocomposite films
Authors: Low HY , Liu TX , Loh WW
Published: August 2004

The moisture transport properties of a polyamide 6/clay nanocomposite have been studied through moisture sorption and permeation rate measurements. The temperature and concentration dependence of the steady state moisture uptake and permeation rate from the two types of experiment are distinctly different. The activation energy of moisture permeation obtained from the sorption experiment is lower than that derived from the permeation measurement. The interaction and contribution of the diffusion parameter and solubility parameter shows a complex moisture transport behavior in these nanocomposite films. Copyright © 2004 Society of Chemical Industry
Crystallization of the γ form in random propylene‐ethylene copolymers
Authors: Marigo Antonio , Causin Valerio , Marega Carla , Ferrari Paolo
Published: August 2004

Wide‐angle X‐ray scattering and differential scanning calorimetry measurements have been conducted on seven random copolymers of propylene with ethylene in order to study the γ phase formation as a function of the comonomer content. The lamellar morphology of the samples was also investigated by small‐angle X‐ray scattering. The content of the γ phase was found to go through a maximum with crystallization temperature and to increase with comonomer concentration, up to a point (ethylene ≥6.5 wt%) where the latter parameter became less influential. The multiple melting endotherms behaviour of the samples was studied by DSC and temperature‐controlled diffractometric techniques. The attribution of the DSC peaks to the different isotactic polypropylene polymorphs that form in these conditions was confirmed. The results obtained permitted us to ascertain that, in the experimental conditions chosen, some further formation of crystallites takes place during the quenching to room temperature after the crystallization isotherm. In this phase, the chains organize themselves in stacks with thin lamellae, forming a distinct population with respect to those formed on isothermal crystallization. The melting of the thinner lamellae determines a convergence of the two populations into just one, still retaining an organization in stacks, that gradually disappears until complete melting of the material. Copyright © 2004 Society of Chemical Industry
Measurement of the thermal diffusivity and specific heat capacity of polyethylene foams using the transient plane source technique
Authors: Almanza O , Rodríguez‐Pérez MA , de Saja JA
Published: August 2004

Thermal diffusivity and specific heat at constant pressure of a collection of crosslinked closed cell polyethylene foams have been measured at room temperature using the transient plane source (TPS) method. A theoretical model to predict the thermal diffusivity has been proposed. The predictions of this model are in good agreement with the observed experimental trends. The theoretical model predicts a dependence of the thermal diffusivity on the density and other foam characteristics such as carbon black content and cell size. Copyright © 2004 Society of Chemical Industry
Frontal copolymerization of 2‐hydroxyethyl methacrylate and ethylene glycol dimethacrylate without porogen: comparison with suspension polymerization
Authors: Pujari NS , Vishwakarma AR , Pathak TS , Mule SA , Ponrathnam S
Published: August 2004

Networked, crosslinked poly[(2‐hydroxyethyl methacrylate)‐co‐(ethylene glycol dimethacrylate)] (HEMA‐EGDM) was synthesized by frontal polymerization (FP) using azobisisobutyronitrile as initiator. HEMA‐EGDM copolymers of similar composition were also synthesized by suspension polymerization. The two sets of copolymers were characterized for functional groups (IR), pore volume (mercury intrusion porosimetry), surface area (nitrogen adsorption) and morphology (scanning electron microscopy). FP‐generated polymeric network structures had higher internal pore volumes and surface areas but their surface morphologies were inferior to those of copolymers synthesized by suspension polymerization. Copyright © 2004 Society of Chemical Industry
Effects of molecular weight distribution on the spinodal temperature of polymer mixtures
Authors: Kim JW , Kim Y , Kim CK
Published: August 2004

The effects of molecular weight distribution on the phase stability of polymer mixtures were explored theoretically and experimentally. Based on the lattice‐fluid theory and volume‐fluctuation thermodynamics, the spinodal conditions for a lattice‐fluid mixture of two polymers with molecular weight distribution were derived. The results indicated that the phase stability of a polymer mixture decreases by increasing the molecular weight distribution of polymers in the blend. To confirm the theoretical results with experiments, the changes in the spinodal temperatures of poly(ethyl methacrylate)/polystyrene (PEMA/PS) blends and tetramethyl polycarbonate/polystyrene (TMPC/PS) blends were examined when each component has a different molecular weight distribution. When the weight‐average molecular weight of each component is the same, a blend composed of polymers having broad molecular weight distribution always exhibited lower phase separation than that composed of polymers having narrow molecular weight distribution at the same blend composition. Copyright © 2004 Society of Chemical Industry
PBT blends with rigid polymer and elastomer inclusions: the effect of component type and reactivity on mechanical behaviour
Authors: Kelnar Ivan , Kotek Jiří , Munteanu Bogdanel S , Kaprálková Ludmila
Published: August 2004

The present study shows the potential of the poly(butylene terephthalate) (PBT) matrix to form ternary blends with well‐balanced properties, analogous to Polyamide 6 (PA6) systems with a very fine (<100 nm) separately dispersed rigid polymer (poly(styrene‐co‐maleic anhydride)) and elastomer (maleated ethylene‐propylene elastomer). The use in PBT blends of maleated components analogous to those in the PA6 systems was much less effective, due to the presence of larger particles. Enhancement of all properties, including toughness, was found in the case of a blend containing at least one component with epoxide groups, such as rigid styrene‐glycidyl methacrylate copolymer or elastomeric poly[(ethylene)‐co‐(methyl acrylate)‐co‐(glycidyl methacrylate)]. In this case, the reactive compatibilization of the epoxy‐group‐containing component caused refinement of particle size of the other component due to enhanced viscosity. As a result, more advantageous micromechanical behaviour of this ternary in comparison with the binary system occurs. The PBT matrix offers a similar potential to PA6 in synergistic influencing of both well‐dispersed phases. This work supports the universality of rigid polymer‐elastomer combination for the enhancement of the properties of pseudoductile polymers. Copyright © 2004 Society of Chemical Industry
Structure and property study of nylon‐6/clay nanocomposite fiber
Authors: Yoon KwanHan , Polk Malcolm B , Min Byung G , Schiraldi David A
Published: August 2004

The crystal structures of nylon‐6 and nylon‐6/clay fibers were investigated on annealing and drawing. Annealing increased the γ‐crystalline form of both fibers, as indicated by the DSC curves, and its effect was dominant in nylon‐6/clay fiber. On drawing, the γ‐crystalline form was easily converted into the α form in nylon‐6, whereas it was still observed at a relatively high spin‐draw ratio in nylon‐6/clay fiber. However, although the α‐crystal form was dominant in nylon‐6, the γ‐crystal form was dominant in nylon‐6/clay with annealing and drawing, on the basis of the XRD data. The fast crystallization rate of nylon‐6/clay compared with pure nylon‐6 was confirmed, on the basis of the Avrami exponent. The initial modulus of nylon‐6/clay fiber was 30 % higher than the neat nylon‐6 fiber. The reinforcing effect of clay on the dynamic storage modulus was observed. Copyright © 2004 Society of Chemical Industry
Preparation and properties of poly(L‐lactic acid) scaffolds by thermally induced phase separation from a ternary polymer–solvent system
Authors: Li Shirong , La Carrubba Vincenzo , Piccarolo Stefano , Sannino Diana , Brucato Valerio
Published: August 2004

Poly(L‐lactic acid) (PLLA) foams for tissue engineering were prepared via thermally induced phase separation of a ternary system PLLA/dioxane/tetrahydrofuran (THF) followed by double solvent exchange (water and ethyl alcohol) and drying. An extension to solidification from solution of a previously developed method for solidification from the melt was adopted. The technique is based on a continuous cooling transformation (CCT) approach, consisting in recording the thermal history experienced by rapidly cooled samples and then analyzing the resulting sample morphology. Different foams were produced by changing the relative amount of dioxane and THF in the starting solution while the amount of polymer was kept constant. Results show that the final morphology and crystallinity (measured by DSC) depend on solvent power, which in its turn was determined by the ratio dioxane/THF, and a minimum of pore size, optimum final crystallinity and crystallization rate were achieved for a system containing 70 % of dioxane. Under this condition, a higher bulk density (evaluated by Hg intrusion porosimetry) and a larger specific surface area (measured by BET N2 sorption technique) was achieved. Copyright © 2004 Society of Chemical Industry
FTIR study of poly(propylene carbonate)/bisphenol A blends
Authors: Fei Bin , Chen Cheng , Peng Shuwen , Zhao Xiaojiang , Wang Xianhong , Dong Lisong
Published: August 2004

A systematic investigation by FTIR spectroscopy was undertaken on blends of poly(propylene carbonate) (PPC) and bisphenol A (BPA). It provided direct evidence of the hydrogen bond (H‐bond) between BPA OH groups and PPC CO groups. Using a curve‐fitting method, qualitative as well as quantitative information concerning this H‐bond interaction was obtained. The inter‐H‐bond in PPC/BPA blends was weaker than the self‐H‐bond in BPA. The absorptivities of the free and the H‐bonded CO groups were nearly equal. The fraction of H‐bonded CO in the blends increased with BPA content and leveled off at a value close to 40 %. Finally, FTIR–temperature measurements of pure PPC and a representative blend were reported: by monitoring the peak areas of CO absorptions, the dissociation of the inter‐H‐bonds and the thermal degradation of PPC were observed. It revealed that the presence of BPA clearly retarded the thermal degradation of PPC. Copyright © 2004 Society of Chemical Industry
Direct electrochemical generation of conducting polymer microcontainers on silicon substrate
Authors: Yuan Jinying , Zhang Deqiang , Qu Liangti , Shi Gaoquan , Hong Xiaoyin
Published: August 2004

Polypyrrole microcontainers with morphology like bowls, cups, goblets and bottles have been electrochemically generated by direct oxidation of pyrrole on a p‐type silicon wafer in aqueous solution of camphorsulfonic acid. The well‐ordered microcontainers stand upright on the working electrode surface and changing the electrochemical polymerization conditions can easily control their morphological features. The growing process of microcontainers was studied by scanning electron microscopy. The microcontainers were characterized as being made of polypyrrole films in the doped state by Raman and IR spectroscopies. Copyright © 2004 Society of Chemical Industry