bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some new results on superimposed codes
Authors: Kim Hyun Kwang , Lebedev Vladimir , Oh Dong Yeol 
Published: August 2004

AbstractA (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

AbstractIn 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

AbstractUsing 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

AbstractProtrusion 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

AbstractSpermiogenesis, 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

AbstractThe 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

AbstractWe 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

AbstractWhey 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

AbstractSummary: 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.imageModel 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

AbstractProlongation 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

AbstractA 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

AbstractOne‐ 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

AbstractEudesm‐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

AbstractSchemes 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

AbstractIt 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

AbstractNeferine 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

AbstractIn 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

AbstractMethacrylic 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

AbstractIn 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