bluuebunny/crossref_metadata_2025_split huggingface dataset:
Even adult sex ratios in lemurs: Potential costs and benefits of subordinate males in Verreaux's sifaka (Propithecus verreauxi) in the Kirindy Forest CFPF, Madagascar
Authors: Kappeler Peter M. , Mass Vanessa , Port Markus 
Published: May 2009

AbstractOptimal group size and composition are determined by both the costs and benefits of group living for the group's members. Verreaux's sifakas (Propithecus verreauxi), a diurnal lemur, form multimale multifemale groups with the tendency toward even adult sex ratios despite a small average number of females per group. The unexpected presence of multiple adult males may be explained by tolerance of other group members if subordinate males provide benefits to the group that outweigh the costs associated with their presence. Results based on both demographic data collected over a 13‐year period and behavioral observations suggest that subordinate males provide no benefits in terms of infant survival and defense against group takeover by outside males. Although groups with more males are more likely to win intergroup encounters, subordinate males do not participate in these encounters more often than expected. Subordinate males are not costly to other group members in terms of direct intragroup feeding competition, but aggression rates between dominant and immigrated subordinate males increase in the mating season. Even though subordinate males provide very few benefits to the group, they are not very costly either and thus may be tolerated by resident females and dominant males. This tolerance may help to partially explain the tendency towards their unusual adult sex ratio. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.
A Supramolecular Approach for Preparation of Size‐Controlled Nanoparticles
Authors: Wang Hao , Wang Shutao , Su Helen , Chen Kuan‐Ju , Armijo Amanda Lee , Lin Wei‐Yu , Wang Yanju , Sun Jing , Kamei Ken‐ichiro , Czernin Johannes , Radu Caius G. , Tseng Hsian‐Rong 
Published: May 2009

AbstractAus drei Bausteinen entstehen auf der Grundlage eines Cyclodextrin‐Adamantan‐Erkennungssystems supramolekulare Nanopartikel (SNPs) variabler Größe (30–450 nm). Die Bioverteilung und Lymphknotendrainage der SNPs in Mäusen wurde mit Positronenemissionstomographie untersucht. Die Größen der SNPs beeinflussen ihr In‐vivo‐Verhalten (siehe Bild).magnified image
Bioinspired Colorimetric Detection of Calcium(II) Ions in Serum Using Calsequestrin‐Functionalized Gold Nanoparticles
Authors: Kim Sunghyun , Park Jeong Won , Kim Dongkyu , Kim Daejin , Lee In‐Hyun , Jon Sangyong 
Published: May 2009

AbstractZuviel Calcium im Blut? Mit Calsequestrin (CSQ) funktionalisierte Goldnanopartikel durchlaufen eine Calcium‐abhängige CSQ‐Polymerisation, die mit einem Farbwechsel (siehe Bild) und einer Niederschlagsbildung einhergeht. Dieses Sensorsystem ist spezifisch für Ca2+‐Ionen. Die Unterschiede zwischen normalen und krankheitsbedingten (hypercalcämischen) Ca2+‐Ionenkonzentrationen im Serum lassen sich mit bloßem Auge wahrnehmen.magnified image
Disterolphospholipids: Nonexchangeable Lipids and Their Application to Liposomal Drug Delivery
Authors: Huang Zhaohua , Jaafari Mahmoud Reza , Szoka Francis C. 
Published: May 2009

AbstractCholesterin an der Kette: Der Cholesterinaustausch ist einer der Hauptgründe für die Unbeständigkeit von Liposomen im Blut. Durch Bildung eines kovalent verbundenen Cholesterin‐Glycerophosphocholin‐Hybrids bleibt der stabilisierende Effekt des freien Cholesterins erhalten, sein Austritt aus der Doppelschicht wird aber verhindert. Disterophospholipide wie1sind somit wertvolle Komponenten für Liposomenformulierungen.magnified image
Nuclear Spin‐Noise Spectra of Hyperpolarized Systems
Authors: Desvaux Hervé , Marion Denis J. Y. , Huber Gaspard , Berthault Patrick 
Published: May 2009

AbstractDas NMR‐Spinrauschen eignet sich besonders, um verdünnte hyperpolarisierte Spezies zu charakterisieren. Durch kontinuierliche Aufzeichnung der Rauschabsorption an der Larmor‐Frequenz lassen sich T1 und T2* unabhängig vom statischen magnetischen Feld bestimmen. Induktiv gekoppelte Mikrospiralen im Inneren der NMR‐Röhrchen (siehe Bild) ermöglichen die Aufnahme von 129Xe‐Spinrauschenspektren ohne Radiofrequenzanregung.magnified image
Anellierung und Arylierung stabilisieren Porphyrinoide
Authors: Jux Norbert 
Published: May 2009

AbstractMehr π, bitte: Ein nichtmetalliertes, benzanelliertes Triphyrin mit [2.1.1]‐Brückenmuster (1) und ein von Azulen abgeleitetes, tetrakationisches All‐Kohlenstoff‐Porphyrinoid (2) wurden hergestellt. 1 kann Ausgangspunkt für eine eigenständige Metallkomplexchemie der Triphyrine sein, und 2 könnte sich für die molekulare Elektronik und als Rezeptor für schwach bindende Anionen eignen.magnified image
Symmetry‐Based Design for the Chemoenzymatic Synthesis of Oseltamivir (Tamiflu) from Ethyl Benzoate
Authors: Sullivan Bradford , Carrera Ignacio , Drouin Melissa , Hudlicky Tomas 
Published: May 2009

AbstractAusgehend von Ethylbenzoat gelang eine kurze chemoenzymatische Formalsynthese von Oseltamivir. Die Schlüsselschritte sind eine durch Toluoldioxygenase vermittelte Dihydroxylierung, eine Hetero‐Diels‐Alder‐Reaktion und die Bildung einer Acetamidofunktion an C4. Die Synthese benötigt insgesamt zehn Stufen und umfasst eine Verschiebung der Doppelbindung unter Eliminierung einer Hydroxygruppe an C2 (siehe Schema).magnified image
A Supramolecular Approach for Preparation of Size‐Controlled Nanoparticles
Authors: Wang Hao , Wang Shutao , Su Helen , Chen Kuan‐Ju , Armijo Amanda Lee , Lin Wei‐Yu , Wang Yanju , Sun Jing , Kamei Ken‐ichiro , Czernin Johannes , Radu Caius G. , Tseng Hsian‐Rong 
Published: May 2009

AbstractA supramolecular approach has been developed for the preparation of supramolecular nanoparticles (SNPs) with variable sizes (30–450 nm) from three different molecular building blocks using a cyclodextrin/adamantane recognition system. Positron emission tomography (PET) was employed to study the biodistribution and lymph node drainage of the SNPs in mice. The sizes of the SNPs affect their in vivo characteristics (see picture).magnified image
Structural Characterization and Remarkable Axial Ligand Effect on the Nucleophilic Reactivity of a Nonheme Manganese(III)–Peroxo Complex
Authors: Annaraj Jamespandi , Cho Jaeheung , Lee Yong‐Min , Kim Sung Yeon , Latifi Reza , de Visser Sam P. , Nam Wonwoo 
Published: May 2009

AbstractThe dark side of the Mn: A manganese(III) complex bearing a 13‐membered macrocyclic ligand (1, see picture) binds a peroxo ligand in a side‐on η2 fashion. The reactivity of 1 is influenced by the introduction of anionic ligands trans to the peroxo group. Electronic and structural changes upon trans‐ligand binding explain the increased nucleophilicity of the resulting complexes 1‐X.magnified image
Asymmetric Syntheses of l,l‐ and l,d‐Di‐myo‐inositol‐1,1′‐phosphate and their Behavior as Stabilizers of Enzyme Activity at Extreme Temperatures
Authors: Longo Christina M. , Wei Yang , Roberts Mary F. , Miller Scott J. 
Published: May 2009

AbstractThe big “DIP”per: The preparation of both l,l‐DIP and l,d‐DIP (see structures) involves a complex case of double asymmetric induction in the key step of the synthesis. The differential ability of each isomer to contribute to thermoprotection in the context of a key enzyme has been assessed and both isomers of DIP are shown to possess biological activity.magnified image
Efficient and Economical Access to Substituted Benzothiazoles: Copper‐Catalyzed Coupling of 2‐Haloanilides with Metal Sulfides and Subsequent Condensation
Authors: Ma Dawei , Xie Siwei , Xue Peng , Zhang Xiaojing , Dong Jinhua , Jiang Yongwen 
Published: May 2009

AbstractDon′t tell azole: The first metal‐catalyzed direct coupling of metal sulfides with aryl halides and subsequent intramolecular condensation provided substituted benzothiazoles (see scheme). A wide range of functional groups are tolerated under the reaction conditions.magnified image
End‐On Nitrogen Insertion of a Diazo Compound into a Germanium(II) Hydrogen Bond and a Comparable Reaction with Diethyl Azodicarboxylate
Authors: Jana Anukul , Sen Sakya S. , Roesky Herbert W. , Schulzke Carola , Dutta Sudipta , Pati Swapan K. 
Published: May 2009

AbstractA happy ending: The germanium(II) hydride [LGeH], where L=[HC{(CMe)(2,6‐iPr2C6H3N)}2], reacts with a diazoalkane to form the hydrazone derivative (see picture). The reaction proceeds through the unprecedented end‐on nitrogen insertion of the diazo compound.magnified image
Nuclear Spin‐Noise Spectra of Hyperpolarized Systems
Authors: Desvaux Hervé , Marion Denis J. Y. , Huber Gaspard , Berthault Patrick 
Published: May 2009

AbstractSpin‐noise appeal: Detection of NMR spin‐noise is very appealing when dilute hyperpolarized species are considered. Continuous monitoring of the noise absorption at the Larmor frequency enables determination of T1 and T2*, independently of the static magnetic field. An inductively coupled microcoil located inside the NMR tube (see picture) allows acquisition of 129Xe spin‐noise spectra without radio‐frequency excitation.magnified image
Annulation and Arylation Stabilize New Porphyrinoids
Authors: Jux Norbert 
Published: May 2009

AbstractMore π, please! A free‐base, benzannelated triphyrin with a [2.1.1] bridging pattern (1) and an azulene‐derived tetracationic all‐carbon porphyrinoid (2) are discussed. Compound 1 can be used to form metal triphyrin complexes, and 2 shows potential in molecular electronics and as a receptor for weakly binding anions.magnified image
Reactive extrusion process for the grafting of maleic anhydride onto linear low‐density polyethylene with ultraviolet radiation
Authors: Saade‐Caballero H. , Martínez‐Colunga J. G. 
Published: May 2009

AbstractIn this work, we chemically modified linear low‐density polyethylene with maleic anhydride in the molten state using, in a first step, different doses of ultraviolet irradiation to generate hydroperoxide groups, which were highly reactive at the processing temperature. Then, in a second reactive extrusion step, maleic anhydride was grafted to the linear low‐density polyethylene under different processing conditions. Characterization of the modified and unmodified linear low‐density polyethylene material was performed with Fourier transform infrared spectroscopy, differential scanning calorimetry, and nuclear magnetic resonance. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Studies on the influence of molecular weight and isotacticity of polypropylene on the formation of mesomorphic phase
Authors: Singh Gurmeet , Kaur Sukhdeep , Kothari Ajay V. , Naik Dhananjay G. , Vyas Priyanshu B. , Gupta Virendra K. 
Published: May 2009

AbstractPolypropylene (PP) blends with various molecular weight and isotacticity were prepared through solution blending and subjected to rapid melt quenching. Structural changes in the PP matrix during mesomorphic phase formation were measured by FTIR spectroscopy and wide‐angle X‐ray diffraction measurements. The blends with different molecular weight and isotacticity provided the pathway to understand their influence on mesomorphic phase formation. It is observed that low molecular weight PP with low isotacticity forms mesomorphic phase, whereas high molecular weight and low isotactic PP does not lead to the formation of mesomorphic phase. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Study of the behavior of blends of a poly(hydroxybutyrate‐valerate) copolymer, polypropylene, and SEBS
Authors: Marcilla A. , Garcia‐Quesada J. C. , Lopez M. , Gil E. 
Published: May 2009

AbstractPolyhydroxyalkanoates are a type of polymers with a clear renewable origin, as different types of microorganisms can produce them. Unfortunately, their mechanical properties are not usually as good as those of conventional polymers and for a moment their price is relatively higher; these are two of the reasons why it is suggested in the bibliography that they can be employed forming part of blends with conventional polymers. In the present work, blends of a poly(hydroxybutyrate‐valerate) (PHBV) copolymer and a polypropylene resin have been successfully processed using PHBV concentrations up to 20 phr with internal mixer and a hot plate press. Processability and applicability of such blends logically depend on their properties, and for this reason morphology, rheological, thermal properties, and tensile strength for all samples have been evaluated. Ternary blends, incorporating a poly(styrene‐ethylene‐butylene) copolymer have also been obtained and the influence of the blends properties has been analyzed. Results have shown that the rheological behavior and crystallization process of the system is markedly dependent on the blend composition. Although tensile strength significantly decreases with PHBV concentration, the use of low concentrations of the styrene‐ethylene‐butylene‐styrene copolymer could improve the elongation at break to a certain extent. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation and characterization of epoxidate poly(1,2‐butadiene)–toughened diglycidyl ether bisphenol‐A epoxy composites
Authors: He Jie , Wang Jinwei 
Published: May 2009

AbstractBy the oxidation of liquid poly(1,2‐butadiene) (LPB) with H2O2/HCOOH, epoxidate poly(1,2‐butadiene) (ELPB) was obtained as a toughening agent to prepare diglycidyl ether bisphenol‐A (DGEBA) epoxy composites by using V115 polyamide(PA) as a cross‐linking agent. DGEBA, ELPB, and the composites were effectively cured by PA at 100°C for 2 h followed by postcuring at 170°C for 1 h. Thermal gravimetric analysis results in air and nitrogen atmosphere showed that the thermal stability of composites could be improved by the addition of ELPB. Compared with DGEBA/PA, the composites exhibited a decrease in strength at yield but an increase in strain at break with the increase in ELPB amount. The composite with 10% ELPB exhibited both thermal stability and tenacity superior to those of DGEBA/PA and composites with 5 and 20% ELPB, respectively. The improvements in thermal and mechanical properties of composites depended on the formation of Inter Penetrating Networks (IPN) among DGEBA/PA/ELPB and their distributions in the matrix. At an appropriate ELPB amount, the IPN, mostly made of DGEBA/PA/ELPB, may be distributed more evenly in the matrix; less ELPB resulted in the formation of IPN mainly made of DGEBA/PA; excessive addition of ELPB resulted in the local aggregation of ELPB/PA and phase separations. The toughening mechanism was changed from chemically forming IPN made of DGEBA/PA/ELPB to physically reinforcing DGEBA/PA by ELPB/PA with the increase in ELPB addition. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Modification of Fe2O3 and its effect on the heat‐resistance of silicone rubber
Authors: Shentu Baoqing , Gan Tengfei , Weng Zhixue 
Published: May 2009

AbstractBy means of the wet chemical surface modification, the surface of Fe2O3 was modified by vinyltrimethoxysilane (VTMS). Infrared spectroscopy (IR) was used to investigate the structure of the modified Fe2O3, and the result showed that VTMS has been attached onto the surface of Fe2O3. Effect of VTMS concentration on the active index of the modified Fe2O3 was also studied, and the result indicated that the active index of the modified Fe2O3 increases with the increase of VTMS concentration and the optimal concentration of VTMS is 12 wt %. The effect of the modified Fe2O3 on the tear strength of silicone rubber before and after aging was studied and it was found that in comparison with the unmodified Fe2O3 the addition of the modified Fe2O3 results in the significant increase of the tear strength before ageing because of the increase of the crosslinking density of silicone rubber. The tear strength of silicone rubber filled with the modified Fe2O3 after ageing is higher than that with the unmodified Fe2O3, indicating that the modification of Fe2O3 can improve the heat‐resistance of silicone rubber owing to the fine dispersion of the modified Fe2O3 in silicone rubber. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Comparing elastomeric behavior of block and random ethylene–octene copolymers
Authors: Wang H. P. , Chum S. P. , Hiltner A. , Baer E. 
Published: May 2009

AbstractThis work compared the elastomeric properties of two low‐crystallinity ethylene–octene copolymers. One was a block copolymer with lamellar crystals and the other was a random copolymer with fringed micellar crystals. The comparison of the stress–strain behavior at 23°C revealed that the initial elastic modulus and the yield stress depended only on the crystallinity of the copolymer. When the temperature was raised above 23°C, melting of the fringed micellar crystals of the random copolymer caused a rapid decrease in the modulus. Some decrease in the modulus of the block copolymer over the same temperature range was attributed to the crystalline α‐relaxation. Both polymers exhibited strain‐hardening, ultimate fracture at high strains, and high recovery after fracture. However, in the block copolymer, the onset of strain‐hardening and the ultimate fracture occurred at higher strains. The block copolymer also showed higher recovery from high strains. The initial stretching resulted in a permanent change in the stress–strain curve. It was suggested that following the onset of crystal slippage at the yield, the crystals underwent permanent structural changes through the course of the strain‐hardening region. The transformation of the fringed micellar crystals occurred at lower strains than the transformation of the lamellar crystals. The extent of the structural transformation was described by the crosslink density and the strain‐hardening coefficient extracted from elasticity theory. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Monomers for adhesive polymers, 8a crosslinking polymerization of selected N‐substituted bis(acrylamide)s for dental filling materials
Authors: Pavlinec Juraj , Moszner Norbert 
Published: May 2009

AbstractThe free‐radical polymerization of bis‐(N‐ethylacrylamido)‐ethylenglycol (I), N,N′‐dimethyl‐1,6‐bis (acrylamido)‐hexan (II), and N,N′‐diethyl‐1,3‐bis(acrylamido)‐propan (III) were investigated. The cross‐linking polymerization was followed in bulk by using the ampoules technique and gravimetry. Polymerizations exhibited an abnormal kinetic behavior. For the monomer II, for example, the reaction order to 2,2′‐ azobisisobutyronitril (AIBN) initiator of 1.28, and the polymerization overall activation energy of 151 kJ/mol between 50 and 75°C were determined. The increasing temperature and decreasing initiator concentration resulted in an increase of double bonds consumption in the formed polymer network. At 75°C the residual unsaturation was under 2%, compared with 9.9% at 50°C. The monomer conversion‐time dependences were complemented also with differential scanning calorimetry (DSC) recording the heat released during polymerization. The extension of peak time with decreasing the instant heat flow rate at this point sort the studied bis(acrylamide)s according the reactivity in the following sequence: monomer III > I >II. The polymer samples sol–gel analyses in ethanol allowed the determination of the molecular weight Mc between the network crosslinks. The presence of microgel particles at the very beginning of polymerization and the changes in chain conformation with temperature we consider as the way in which was affected the polymerization kinetics of these monomers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Polyurethane–solid wood composites. II. Flammability parameters
Authors: Gao Zhenhua , Su Wenqiang , Wu Di 
Published: May 2009

AbstractPolyurethane (PU)–solid wood composites with good mechanical properties and dimensional stability have been prepared in the presence of four amine catalysts. Cone calorimetry and scanning electron microscopy (SEM) have been employed to characterize and evaluate the effects of the catalyst species on the flammability of the PU–wood composites. The results indicated that the PU–wood composites prepared in the presence of various catalysts had somewhat better flame resistance than the untreated wood control, as manifested in various flammability parameters (longer time to sustained ignition and time to peak heart rate release, larger mass and fire performance index (FPI), and lower mean HRR, mass loss rate, and peak HRR). The variations in the flame resistances of the PU–wood composites can be attributed to the various morphologies of the PU resin and the wood that resulted from the use of the various catalysts, as indicated by SEM micrographs. The PU–wood composite prepared in the presence of N‐methylmorpholine (NMM) as catalyst showed the best flame resistance, since the PU resin formed abundant PU foam that extended throughout the wood. This foam was effective in retarding the transfers of heat and combustible substances as well as the pyrogenation. In terms of FPI values, the flame resistances of these PU–wood composites decreased according to the catalyst used in the order NMM, triethanolamine, diethylenetriamine, and triethylenediamine. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Abrasion studies of nylon 6/montmorillonite nanocomposites using scanning electron microscopy, fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy
Authors: Zhou Qi , Wang Kean , Loo Leslie S. 
Published: May 2009

AbstractIn this article, abrasion performance of commercial nylon 6 and nylon 6/montmorillonite (MMT) nanocomposites was studied. The polymer nanocomposites showed poor abrasion resistance compared to the neat polymer. The wear loss increased linearly with clay concentration. Changes in surface morphology, composition, and structure were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR)‐attenuated total reflection spectroscopy, and X‐ray photoelectron spectroscopy (XPS). SEM images showed that all the abraded surfaces contained fractured particles. However, the abraded nanocomposite surfaces had much deeper grooves compared to the homopolymer. FTIR results showed an increase in the amount of α crystals and a decrease in the amount of γ crystals on all the surfaces after abrasion. This was attributed to the strain‐induced γ to α crystal transformation. The largest amount of α crystals was formed in the abraded surface of pure nylon 6, and the amount of α crystals formed decreased with increasing MMT content. XPS results showed an increase in the [Si]/[N] elemental ratio for all nanocomposites after abrasion, indicating an increase in the clay content of the surface. Abrasive wear mechanism is as follows: (1) tensile tearing is the dominant wear mechanism for all the samples; (2) the cutting mechanism becomes more important when MMT content increases; (3) the polymer matrix is easier to be removed than clay during the abrasion process; (4) in nylon 6/MMT systems, the poor abrasion resistance is attributed to defects at the clay‐polymer interface, resulting in greater wear of the polymer matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009