bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lateral sequence walking in infant Papio cynocephalus: Implications for the evolution of diagonal sequence walking in primates
Authors: Shapiro Liza J. , Raichlen David A. 
Published: June 2004

AbstractOne of the most distinctive aspects of primate quadrupedal walking is the use of diagonal sequence footfalls in combination with diagonal‐couplets interlimb timing. Numerous hypotheses have been offered to explain why primates might have evolved this type of gait, yet this important question remains unresolved. Because infant primates use a wider variety of quadrupedal gaits than do adults, they provide a natural experiment with which to test hypotheses about the evolution of unique aspects of primate quadrupedalism. In this study, we present kinematic data on two infant baboons (Papio cynocephalus) in order to test the recent hypothesis that diagonal sequence, diagonal couplets walking might have evolved in primates because their limb positioning provides stability in a small branch environment (Cartmill et al. [2002] Zool J Linn Soc 136:401–420). To assess hindlimb position at the moment of forelimb touchdown, we measured hindlimb angular excursion and ankle position for 84 walking strides, across three different types of gaits (diagonal sequence, diagonal couplets (DSDC); lateral sequence lateral couplets (LSLC); and lateral sequence diagonal couplets (LSDC)). Results indicate that if a forelimb were to contact an unstable substrate, LSLC walking provides as much, and perhaps more, stability when compared to DSDC walking. Therefore, it appears that this moment in a stride was unlikely to be a particularly important selective factor in the evolution of DSDC walking. Further insight into this issue will likely be gained by observations of primate quadrupedalism in natural environments, where the use of lateral sequence gaits might be more common than currently known. Am J Phys Anthropol 126:205–213, 2005. © 2004 Wiley‐Liss, Inc.
Calcaneal measurement in estimation of stature of South African blacks
Authors: Bidmos Mubarak , Asala Samuel 
Published: June 2004

AbstractStature (height) is an important factor in establishing the identity of a person in the living as well as in the skeletonized state. When stature is estimated from the bones of the limbs, regression equations, which estimate the ratios of the lengths of bones to the height of the individual, are generated. The majority of bones that were used previously were the long bones. The calcaneus was used for estimating stature only in American whites and blacks (Holland [1995] Am. J. Phys. Anthropol. 96:315–320). The regression equations that he generated were found to be useful for stature estimation in these population groups. Since the calcaneus has not been used for the same purpose in South Africa, the aim of this study was to derive regression equations that will allow this bone to be used for stature estimation in South African blacks. In total, 116 complete skeletons (60 males and 56 females) were selected from the Raymond A. Dart Collection of Human Skeletons, School of Anatomical Sciences, University of the Witwatersrand (Johannesburg, South Africa). The skeletal heights of these sets of skeletons were calculated using the anatomical method of Fully ([1956] Ann. Med. Leg. 35:266–273). Nine parameters of the calcaneus were measured and matched against skeletal heights, using univariate and multivariate regression methods. Regression equations were obtained for estimation of the stature of the South African black population from the calcaneus. The standard error of estimate that was obtained with univariate regression analysis was higher than the corresponding values using multivariate regression analysis. In both cases, the standard errors of estimate compared well with the values obtained for fragmentary long bones by previous authors. Am J Phys Anthropol 126:335–342, 2005. © 2004 Wiley‐Liss, Inc.
Funktion der Antigen‐Transportmaschinerie TAP im zellulären Immunsystem
Authors: Beismann‐Driemeyer Silke , Tampé Robert 
Published: June 2004

AbstractDas Immunsystem besteht aus unterschiedlichen Typen von Zellen und Molekülen, deren komplexe Wechselwirkungen ein effizientes System zur Verteidigung eines Individuums gegen eindringende Pathogene und gegen eigene transformierte Zellen bilden. Angeborene Immunität bezeichnet die sofortige Reaktion auf Mikroorganismen, unabhängig von der Art des Eindringlings. Erworbene Immunität dagegen ruft eine spezifische Immunantwort hervor, wodurch das Individuum vor Fremdzellen von bestimmten Eindringlingen oder sogar vor Tumorzellen geschützt wird, und gibt lang anhaltenden Schutz bei wiederholter Exposition. Antikörper‐Produktion und zellvermittelte Antworten sind die zwei verzahnten Zweige des erworbenen Immunsystems. Normalerweise aktivieren auf der Zelloberfläche präsentierte antigene Peptide die zelluläre Immunantwort. Der Transportkomplex TAP hat eine Schlüsselfunktion bei der Antigenprozessierung und ‐präsentation. Dieser Aufsatz diskutiert die neuesten Forschungsergebnisse zur Struktur und zum Mechanismus sowie zu den mit Krankheiten verbundenen Fehlfunktionen des TAP‐Komplexes.
Function of the Antigen Transport Complex TAP in Cellular Immunity
Authors: Beismann‐Driemeyer Silke , Tampé Robert 
Published: June 2004

AbstractThe immune system consists of several kinds of cells and molecules whose complex interactions form an efficient system for the protection of an individual from outside invaders and its own transformed cells. Innate immunity refers to the immediate antimicrobial response that occurs regardless of the nature of the invader. The adaptive immune system, on the other hand, mounts specialized immune responses to protect the individual against foreign cells from specific invaders or even tumorigenic cells, and provides long‐term protection from subsequent exposure to these foreign cells. Antibody production and cell‐mediated responses are the two interconnected branches of the adaptive immune system. Antigenic peptides displayed on the cell surface usually activate the cellular immune response. The transporter associated with antigen processing (TAP) plays a key role in the peptide‐processing and ‐presentation pathway. This Review discusses the latest progress in the structure and mechanism as well as the diseases arising from dysfunction of the TAP complex.
Preparation of two‐layer film having porous structure by emulsion blend technique
Authors: Okubo M. , Terada A. , Kagawa Y. 
Published: June 2004

AbstractA two‐layer film consisting of a tacky layer (air side) and a porous nontacky layer (release‐paper side) was prepared by casting blend emulsion on a release paper, in which 150‐nm 2‐ethylhexyl acrylate–2‐methoxyethyl acrylate–acrylic acid terpolymer particles having high storage stability and 542‐nm ethyl acrylate–methyl methacrylate copolymer particles having low storage stability were dispersed. Both emulsion particles were produced by emulsifier‐free emulsion copolymerizations. The difference of tackiness between both surfaces increased with increases in the film‐formation time and the concentration of electrolytes in the blend emulsion, and resulted in the two‐layer film. The film had a high water vapor permeability, which is also needed for medical adhesive tape. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2027–2033, 2003
Competitive removal of heavy metal ions by cellulose graft copolymers
Authors: Güçlü Gamze , Gürdağ Gülten , Özgümüş Saadet 
Published: June 2004

AbstractThe effect of composition of graft chains of four types cellulose graft copolymers on the competitive removal of Pb2+, Cu2+, and Cd2+ ions from aqueous solution was investigated. The copolymers used were (1) cellulose‐g‐polyacrylic acid (cellulose‐g‐pAA) with grafting percentages of 7, 18, and 30%; (2) cellulose‐g‐p(AA–NMBA) prepared by grafting of AA onto cellulose in the presence of crosslinking agent of N,N′‐methylene bisacrylamide (NMBA); (3) cellulose‐g‐p(AA–AASO3H) prepared by grafting of a monomer mixture of acrylic acid (AA) and 2‐acrylamido‐2‐methyl propane sulphonic acid (AASO3H) containing 10% (in mole) AASO3H; and (4) cellulose‐g‐pAASO3H obtained by grafting of AASO3H onto cellulose. The concentrations of ions which were kept constant at 4 mmol/L in an aqueous solution of pH 4.5 were equal. Metal ion removal capacities and removal percentages of the copolymers was determined. Metal ion removal capacity of cellulose‐g‐pAA did not change with the increase in grafting percentages of the copolymer and determined to be 0.27 mmol metal ion/gcopolymer. Although the metal removal rate of cellulose‐g‐p(AA–NMBA) copolymer was lower than that of cellulose‐g‐pAA, removal capacities of both copolymers were the same which was equal to 0.24 mmol metal ion/gcopolymer. Cellulose did not remove any ion under the same conditions. In addition, cellulose‐g‐pAASO3H removed practically no ion from the aqueous solution (0.02 mmol metal ion/gcopolymer). The presence of AASO3H in the graft chains of cellulose‐g‐p(AA–AASO3H) created a synergistic effect with respect to metal removal and led to a slight increase in metal ion adsorption capability in comparison to that of cellulose‐g‐pAA. All types of cellulose copolymers were found to be selective for the removal of Pb2+ over Cu2+ and Cd2+. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2034–2039, 2003
Supercritical CO2‐assisted synthesis of poly(acrylic acid)/nylon1212 blend
Authors: Chang Yuning , Xu Qun , Liu Minying , Wang Yudong , Zhao Qingxiang 
Published: June 2004

AbstractPAA/nylon1212 blend was prepared using supercritical CO2 as substrate‐swelling agent and monomer/initiator carrier. Both supercritical CO2/nylon1212 binary system and SC CO2/monomer/nylon1212 ternary system have been studied. Virgin nylon1212 and blends were characterized through differential scanning calorimetry (DSC), infrared spectroscopy (IR), and scanning electron microscopy (SEM). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2040–2044, 2003
Silicon‐containing anionic water‐borne polyurethane with covalently bonded reactive dye
Authors: Wang Huei‐Hsiung , Lin Yi‐Tzun 
Published: June 2004

AbstractA silicon‐containing water‐borne polyurethane (PU) polymer with hydroxyl side groups was synthesized that was stable in basic conditions and also capable of reacting with a reactive dye to form a covalently bonded dye molecule. The silicon‐containing anionic water‐borne PU prepolymer was synthesized from H12‐4,4′‐diphenylmethane diisocyanate (H12‐MDI), polytetramethylene glycol, polydimethylsiloxane (PDMS), 2,2′‐bis(hydroxymethyl), propionic acid (anionic centers), and triethyleneamine using the prepolymer mixing method. Water was then added to emulsify and disperse the resin to form an anionic water‐borne PU prepolymer. N‐(2‐Hydroxyethyl ethylene diamine) (HEDA) was used to extend the prepolymer to form a water‐borne PU polymer with a side chain of hydroxyl groups, which can further react with the reactive dye to form a dyed PU. The reactive dye of chlorosulfuric acid esters of sulfatoethyl sulfones can react with the water‐borne PU polymer. Behaviors of alkali resistance and dyeing properties were observed. In consideration of thermal properties, the dye‐grafted PU polymers exhibited lower glass‐transition temperatures for soft segments and hard segments than those without dye. Concerning mechanical properties, it was found that the modulus and the strength of the dyed PU polymers decreased with grafting of the dye molecule, but elongation at break was increased. The alkali resistance increased with PDMS content. For dye‐uptake properties, the percentage of dye grafting was over 90%. Also, the dye‐grafted PU exhibited a lower percentage of dye migration than that of polymers with ethylene diamine instead of HEDA as a chain extender, and showed greater colorfastness to light. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2045–2052, 2003
Thermal behavior and surface morphology studies on polystyrene grafted sago starch
Authors: Janarthanan Pushpamalar , Yunus Wan Md. Zin Wan , Ahmad Mansor Bin 
Published: June 2004

AbstractPolystyrene grafting onto sago starch was carried out by using ceric ammonium nitrate as a redox initiator. The grafted copolymers were characterized by FTIR, thermogravimetry (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). FTIR spectra analysis of the grafted chain and commercial polystyrene was identical, indicating that styrene was successfully grafted onto sago starch. TGA thermograms and analysis of DSC curves showed that the thermal stability of starch increases as a result of grafting. SEM micrographs showed the deformed prolate ellipsoidal shape of sago starch particles and this shape disappeared in polystyrene grafted sago starch being replaced with a spongy surface with pores. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2053–2058, 2003
Acrylonitrile polymerization initiated by Ce(IV)–cyclohexanone redox system in presence of surfactant
Authors: Patra Manabendra , Behera Ajaya K. , Behera Rajani K. 
Published: June 2004

AbstractThe rate of polymerization of acrylonitrile, using the Ce(IV)–cyclohexanone redox system as an initiator, was studied kinetically, in the presence of 0.015M sodium dodecyl sulfate (SDS), over a temperature range of 25–45°C. The rate of polymerization (RP), percentage of monomer conversion, and rate of Ce(IV) consumption (−RCe) were found to increase with the concentration of SDS, above its CMC. The effect of [AN], [Ce(IV)], [H+], and the ionic strength were also studied. The overall activation energies for the polymerization processes were computed to be 23.14 and 17.64 kcal/mol in the absence and presence of 0.015M SDS. A suitable kinetic mechanistic scheme for the free‐radical mechanism was proposed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2066–2072, 2003
High density polyethylene foams. II. Elastic modulus
Authors: Zhang Yaolin , Rodrigue Denis , Ait‐Kadi Abdellatif 
Published: June 2004

AbstractHigh density polyethylene (HDPE) foams (450–950 kg/m3) were prepared by compression molding and their tensile moduli were measured in order to study the normalized elastic modulus as a function of the normalized density of closed‐cell foams. The tensile data were then used to compare several models of cellular materials and polymer composites to determine which would fit our results. Of all models used, the simple empirical equation of Moore (square power‐law) and the differential scheme predict the data very well in the range of voids volume fraction under study (0–55%). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2120–2129, 2003
High density polyethylene foams. III. Tensile properties
Authors: Zhang Yaolin , Rodrigue Denis , Ait‐Kadi Abdellatif 
Published: June 2004

AbstractThe room temperature tensile properties of closed‐cell polyethylene foams have been investigated. High density polyethylene (HDPE) foams of four different molecular weight were used to study the effect of molecular weight and foam density on mechanical properties during tension and at the break point. It was found that increasing the molecular weight changes the tensile behavior of polyethylene foams from brittle to ductile fractures. For brittle foams, the break strength follows a square power‐law model and the break strain is independent of the volume fraction of the voids. For ductile foams, the normalized yield strength also follows a square power‐law relation with normalized density, the yield strain is similar to the value of the solid polymer and remains constant for all void volume fractions, and the break strain increases with HDPE molecular weight. Finally, the toughness of the foams was found to increase with normalized density and HDPE molecular weight. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2130–2138, 2003
High density polyethylene foams. IV. Flexural and tensile moduli of structural foams
Authors: Zhang Yaolin , Rodrigue Denis , Ait‐Kadi Abdellatif 
Published: June 2004

AbstractHigh density closed‐cell polyethylene foams (450–950 kg/m3) were prepared by compression molding, and their flexural and tensile moduli were measured in order to study (1) the normalized modulus as a function of the normalized density, and (2) the effect of thin skins on flexural and tensile moduli. For the flexural data, it was found that the model of Gonzalez and the I‐beam model of Hobbs predicted the data very well in the range of void volume fractions under study (0–55%). For the tensile data, it was found that a combination of the differential scheme or the square power‐law model with the sandwich structure gave the best predictions. Finally, we found that thin skins have an important effect on the flexural properties of polymer foams, while they seem to have a negligible effect on the tensile properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2139–2149, 2003
Enhancement of mechanical properties and interfacial adhesion of PP/EPDM/flax fiber composites using maleic anhydride as a compatibilizer
Authors: López Manchado M. A. , Arroyo M. , Biagiotti J. , Kenny J. M. 
Published: June 2004

AbstractIn order to improve the compatibility between natural fibers and polypropylene (PP) and polypropylene‐ethylene propylene diene terpolymer (PP‐EPDM) blends, the functionalization of both matrices with maleic anhydride (MA) is investigated in this study. The morphological observations carried out by scanning electron microscopy show that the incorporation of small amounts of functionalized polymer considerably improves the adhesion at the fiber‐matrix interface. In these cases, the fibers are perfectly embedded in the matrix in relation to the composites prepared with the pure homopolymers, and a significant increase in the composite strength is also observed, particularly, after the incorporation of both modified polymers (MAPP and MAEPDM). Thus, it is possible to correlate better interfacial adhesion with the improvement of mechanical properties. It is assumed that the functionalization of the matrix reduces interfacial stress concentrations and may prevent fiber‐fiber interactions, which are responsible for premature composite failure. The crystallization kinetics of PP were also analyzed by differential scanning calorimetry (DSC). It was observed that both flax fiber and rubber behave as effective nucleant agents, accelerating PP crystallization. Moreover, these results are particularly relevant when the grafted matrices are added to the composite. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2170–2178, 2003
Synthesis and characterization of poly(N‐phenyl methacrylamide‐co‐methyl methacrylate) and reactivity ratios determination
Authors: Jayasimha Reddy G. , Venkata Naidu S. , Rami Reddy A. V. 
Published: June 2004

AbstractFree‐radical solution copolymerization of N‐phenyl methacrylamide and methyl methacrylate in various feed ratios was done using a benzoyl peroxide initiator in N,N‐dimethylformamide at 70°C. The structure of the copolymer was elucidated by infrared and proton nuclear magnetic resonance spectroscopy. The copolymer composition was determined from the corresponding 1H‐NMR spectra of the copolymers. Finemann–Ross and Kelen–Tudos methods were used to determine the reactivity ratios of the monomers. The molecular weight distribution of the copolymers was determined using gel permeation chromatography. Thermal properties of the copolymers were determined using differential scanning calorimetry and thermogravimetric analysis (TGA). The activation energy for thermal degradation of the copolymers was determined from the TGA data. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2179–2186, 2003
Gas‐sorption properties of 6FDA–durene/1,4‐phenylenediamine (pPDA) and 6FDA–durene/1,3‐phenylenediamine (mPDA) copolyimides
Authors: Cheng Si‐Xue , Chung Tai‐Shung , Wang Rong , Vora Rohit H. 
Published: June 2004

AbstractWe investigated the sorption isotherms of O2, N2, CH4, and CO2 gases in 6FDA–durene, 6FDA–1,4‐phenylenediamine (6FDA–pPDA), and 6FDA–1,3‐phenylenediamine (6FDA–mPDA) homopolymers and 6FDA–durene/pPDA and 6FDA–durene/mPDA copolyimides. The solubilities decrease in the order of the inherent condensabilities of the penetrant gases, namely, CO2, CH4, O2, and N2. The chemical structures of the polymer, as well as the chain packing, determine the sorption properties of these homopolymers and copolymers. The FDA–durene homopolymer has the highest solubility for all gases because of its high specific free volume and fractional free volume. The solubilities of the copolymers increase with an increasing 6FDA–durene content, while the solubility selectivities of the copolymers only vary slightly. The values of KD (Henry's law constant) and CH′ (Langmuir site capacity) of these copolyimides decrease with a decreasing 6FDA–durene content. To our surprise, contradictory to the previous known fact that the meta‐connected materials tend to have denser molecular packing than that of the para‐linked materials for homopolymers, the 6FDA–durene/mPDA 80/20 copolymer has higher gas solubilities than those of the 6FDA–durene/pPDA 80/20 copolymer. The random moiety sequence within the copolymer may be the main cause for the abnormal phenomenon. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2187–2193, 2003
Characterization of poly(trimethylene/butylene terephthalate) copolymer prepared by the copolycondensation of bis(3‐hydroxypropyl terephthalate) and bis(4‐hydroxybutyl terephthalate)
Authors: Kim Joon Ho , Park Jun Ho , Jang Ho Kyu , Yoon Ji Young , Lyoo Won Seok 
Published: June 2004

AbstractHomopolymers and copolymers were synthesized by polycondensation and copolycondensation, with varying feed ratios of bis(3‐hydroxypropyl terephthalate) (BHPT) and bis(4‐hydroxybutyl terephthalate) (BHBT) at 270°C. In addition, in the mol ratio of 1:1, copoly(trimethylene terephthalate/butylene terephthalate) [P(TT/BT)], with reaction times of 5, 10, 20, 30, and 60 min, was synthesized to identify the chain‐growth process of the copolymers. From differential scanning calorimetry (DSC) data, it was found that a random copolymer might be formed during copolycondensation. The molecular structure of copolymers, formed through the interchange reaction of BHPT and BHBT, was investigated using carbon nuclear magnetic resonance spectroscopy (13C‐NMR). We calculated the sequence‐length distributions of trimethylene and butylene sequences and randomness in the copolymers using 13C‐NMR data. From the values of the number‐average sequence length calculated, it was determined that a random copolymer was produced: This result coincides with previous DSC data. The lateral spacing of the unit cell of the copolymer increased slowly when the mol percent of one monomer was increased to that of the other monomer, indicating broadening of the unit cell by lateral distortion. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2200–2205, 2003
Thermal degradation kinetics of isotactic and atactic polypropylene
Authors: Kumar Ravi , Madras Giridhar 
Published: June 2004

AbstractThe thermal degradation of isotactic and atactic polypropylene was investigated in bulk and in solution. The degradation in bulk was studied with thermogravimetric analysis, and the degradation in solution was studied by the dissolution of the polymer in paraffin oil. The degradation in solution was investigated from 230 to 350°C. The effect of the hydrogen donor on the degradation of the polymer in solution was also studied at 350°C. Continuous distribution kinetics were employed to model the degradation kinetics for the degradation in solution. The rate coefficients were obtained, and the activation energy was calculated from an Arrhenius plot. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2206–2213, 2003