bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endocrine mechanisms of primate life history trade‐offs: Growth and reproductive maturation in vervet monkeys
Authors: Whitten Patricia L. , Turner Trudy R. 
Published: April 2009

AbstractLife history theory predicts that the timing of maturation will result from a trade‐off between growth and the age of first reproduction. This trade‐off and its mechanisms of action are still poorly understood in many species and have not been well studied at the individual level. This study examined hypothesized trade‐offs between growth and reproductive maturation in wild populations of vervet monkeys (Cercopithecus aethiops) from Kenya, East Africa. Individuals were sampled from four populations in widely separated sites differing in temperature, altitude, and rainfall. Biological samples and morphometric measures were collected from 50 adult males, 83 adult females, and 225 juveniles. Gonadal steroids and leptin levels were analyzed by radioimmunoassay of sera from 136 juvenile males and 90 juvenile females. Cross‐sectional profiles of morphometric and endocrine data were used to assess the onset and cessation of growth in relation to sexual maturation. Gonadal steroids were used to assess sexual maturation and breeding onset. Leptin was used as an index of nutritional state. Estimates of mortality were derived from population age‐structure. Across populations, higher resource productivity and nutrient status were associated with more rapid growth. Shorter growth duration was associated with earlier reproductive onset. These findings provide support for models of trade‐offs between the timing of growth completion and reproductive onset, but they are contradicted by the evidence that reproduction precedes the cessation of growth in these populations. The biphasic actions of estradiol provide an alternative model and mechanism for the growth‐reproduction trade‐off. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.
Influence of helminth infections on childhood nutritional status in lowland Bolivia
Authors: Tanner S. , Leonard W.R. , Mcdade T.W. , Reyes‐Garcia V. , Godoy R. , Huanca T. 
Published: April 2009

AbstractInfectious disease, such as diarrheal disease, respiratory infections, and parasitic infections, are an important source of nutritional and energetic stress in many populations. Inspired by the research and methodological innovations of A. Roberto Frisancho, this work considers the impact of childhood environment and local disease ecology on child health and nutritional patterns among an indigenous group in lowland Bolivia. Specifically, we examine the association between soil‐transmitted helminth infection, especially hookworm species, and anthropometric markers of short‐ and long‐term nutritional status. Fecal samples, anthropometric dimensions, and health interviews were collected for 92 children ranging in age from 2.0 to 10.9 years. Microscopic examination revealed high levels of parasitic infection, with 76% of children positive for hookworm species infections (77% of girls and 74% of boys). Less common infections included Ascaris lumbricoides, Trichurius trichiura, and Strongyloides stercoralis with only 15% of children positive for multiple‐species infections. After adjusting for sex and age, no statistically significant associations were observed between helminth infections and the frequency of reported illness or anthropometric measures of nutritional status. These data demonstrate the difficulty of assessing nutritional impacts of endemic infections. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.
Effects of antiepileptic drugs on lipids, homocysteine, and C‐reactive protein
Authors: Mintzer Scott , Skidmore Christopher T. , Abidin Caitlin J. , Morales Megan C. , Chervoneva Inna , Capuzzi David M. , Sperling Michael R. 
Published: April 2009

AbstractObjectiveThe widely prescribed anticonvulsants phenytoin and carbamazepine are potent inducers of cytochrome P450 enzymes, which are involved in cholesterol synthesis. We sought to determine whether these drugs have an effect on cholesterol and other serological markers of vascular risk.MethodsWe recruited 34 epilepsy patients taking carbamazepine or phenytoin in monotherapy whose physicians had elected to change treatment to one of the noninducing anticonvulsants lamotrigine or levetiracetam. Fasting blood samples were obtained both before and 6 weeks after the switch to measure serum lipid fractions, lipoprotein(a), C‐reactive protein, and homocysteine. A comparator group of 16 healthy subjects underwent the same serial studies.ResultsIn the epilepsy patients, switch from either phenytoin or carbamazepine produced significant declines in total cholesterol (−24.8mg/dl), atherogenic (non–high‐density lipoprotein) cholesterol (−19.9mg/dl), triglycerides (−47.1mg/dl) (all p < 0.0001), and C‐reactive protein (−31.4%; p = 0.027). Patients who stopped taking carbamazepine also had a 31.2% decline in lipoprotein(a) level (p = 0.0004), whereas those taken off phenytoin had a decrease in homocysteine level (−1.7μmol/L; p = 0.005). All of these changes were significant when compared with those seen in healthy subjects (p < 0.05). Results were similar whether patients were switched to lamotrigine or levetiracetam.InterpretationSwitching epilepsy patients from the enzyme‐inducers carbamazepine or phenytoin to the noninducing drugs levetiracetam or lamotrigine produces rapid and clinically significant amelioration in several serological markers of vascular risk. These findings suggest that phenytoin and carbamazepine may substantially increase the risk for cardiovascular and cerebrovascular disease. Ann Neurol 2009;65:448–456
Ein Bis(silaselenon) mit zwei donorstabilisierten SiSe‐Bindungen, erhalten durch eine unerwartet stereokonvergente Hydrolyse eines Diselenadisiletans
Authors: Mitra Amitabha , Wojcik Joseph P. , Lecoanet Daniel , Müller Thomas , West Robert 
Published: April 2009

AbstractHydrolyse mit Wasser überführt das durch Umsetzung von racemischem Silylen 1 mit elementarem Selen gebildete Diselenadisiletan 2 in das erste Bis(silaselenon) (3; siehe Struktur; grau C, weiß H, blau N, rot O, violett Se, grün Si; d(SiSe)=215 pm). Diese Reaktion verläuft stereokonvergent: Aus der Mischung der rac‐ und meso‐Isomere von 2 wird nur racemisches 3 erhalten.magnified image
Toroidal Micelles of Uniform Size from Diblock Copolymers
Authors: Huang Haiying , Chung Bonghoon , Jung Jueun , Park Hae‐Woong , Chang Taihyun 
Published: April 2009

AbstractEinheitliche Nanoringe: Stabile toroidale Micellen mit sehr einheitlicher Form und Größe bilden sich spontan aus einem selektiven THF/Ethanol‐Lösungsmittelgemisch (siehe 3D‐AFM‐Bild). Die Donut‐förmigen Micellen können als Template für das Wachsen von Goldnanopartikeln dienen, die sich entlang der Ringoberfläche bilden.magnified image
Umsetzung von Kohlendioxid mit Allenen zu β,γ‐ungesättigten Carbonsäuren
Authors: North Michael 
Published: April 2009

AbstractUngeahnte Reaktivität: Trotz seiner vermeintlichen thermodynamischen und kinetischen Inertheit ist Kohlendioxid eine nützliche Ausgangsverbindung für chemische Synthesen, wie die Addition an Allene unter milden reduktiven Bedingungen in Gegenwart eines Palladium‐Pinzettenkomplexes verdeutlicht (siehe Schema). Diese Umsetzung wird in Zusammenhang mit den Bedingungen für CO2‐Fixierung diskutiert. DMF=N,N‐Dimethylformamid, Tf=Trifluormethansulfonyl.magnified image
9‐Boraanthracene Derivatives Stabilized by N‐Heterocyclic Carbenes
Authors: Wood Thomas K. , Piers Warren E. , Keay Brian A. , Parvez Masood 
Published: April 2009

Abstract2009: Ende der Boraanthracen‐Odyssee: Allgemeine Reaktionswege führen zu Boraanthracen‐Derivaten, die lange postuliert, aber noch nicht beobachtet wurden. Strukturen, photophysikalische Eigenschaften und die bemerkenswerte Reaktionsfähigkeit der Produkte mit Sauerstoff werden beschrieben.magnified image
Titelbild: Nanoscale Chemical Imaging of the Reduction Behavior of a Single Catalyst Particle (Angew. Chem. 20/2009)
Authors: de Smit Emiel , Swart Ingmar , Creemer J. Fredrik , Karunakaran Chithra , Bertwistle Drew , Zandbergen Henny W. , de Groot Frank M. F. , Weckhuysen Bert M. 
Published: April 2009

AbstractEisenkatalysatoren wandeln in der Fischer‐Tropsch‐Synthese aus Kohle oder Biomasse gewonnenes Synthesegas (CO/H2) in flüssige Treibstoffe um. In ihrer Zuschrift auf S. 3686 ff. untersuchen B. M. Weckhuysen, F. M. F. de Groot und Mitarbeiter das unterschiedliche Verhalten von Katalysatorvorstufen bei der Vorbehandlung mit H2 auf der Nanometerskala und auf der Ebene des makroskopischen Katalysators. Ihre Beobachtungen helfen, die Funktionsweise des aktivierten Katalysators zu verstehen.magnified image
A Convenient Method for the Synthesis of α‐Ethynylphospholes and Modulation of Their π‐Conjugated Systems
Authors: Matano Yoshihiro , Nakashima Makoto , Imahori Hiroshi 
Published: April 2009

AbstractMind the (narrow) gap: α‐Ethynylphospholes generated in situ from the corresponding silyl‐capped precursors were converted into a series of α‐(arylethynyl) phospholes bearing functional substituents as well as an α,α′‐linked terphosphole (see scheme). The terphosphole has a narrow HOMO–LUMO gap owing to efficient π conjugation over the three phosphole rings.magnified image
9‐Boraanthracene Derivatives Stabilized by N‐Heterocyclic Carbenes
Authors: Wood Thomas K. , Piers Warren E. , Keay Brian A. , Parvez Masood 
Published: April 2009

Abstract2009: A boraanthracene odyssey: General routes to boraanthracene derivatives—long proposed, but never observed—are disclosed, along with the structural and photophysical properties of these compounds and their remarkable reactivity towards oxygen.magnified image
Synthesis and characterization of chitosan‐g‐methacrylic acid and studies of its additional physicochemical properties, such as swelling, metal‐ion sorption, and flocculation behavior
Authors: Mishra Dinesh Kumar , Tripathy Jasaswini , Srivastava Abhishek , Pandey Peeyoosh Kant , Behari Kunj 
Published: April 2009

AbstractThe aim of this study was to examine the synthesis of a graft copolymer of chitosan and methacrylic acid (MAA) by free‐radical polymerization with a potassium peroxymonosulfate/cyclohexanone (CY) redox system in an inert atmosphere. The optimum reaction conditions affording maximum grafting ratio (%G), grafting efficiency (%E), add on (%A), and conversion (%C) were determined. The grafting parameters were found to increase with increasing concentration of MAA up to 24 × 10−2 mol/dm3, but thereafter, these parameters decreased. With increasing concentration of peroxymonosulfate from 0.6 × 10−2 to 1.2 × 10−2 mol/dm3, %G, %A, and %E increased continuously. All of these grafting parameters increased with increasing concentration of CY up to 1.2 × 10−2 mol/dm3, but beyond this concentration, the grafting parameters decreased. With various concentrations of chitosan from 0.6 to 1.4 g/dm3, the maximum %G, %A, and %E were obtained at 1.4 g/dm3. %G, %A, and %C decreased continuously with various concentrations of hydrogen ions from 2 × 10−3 to 6 × 10−3 mol/dm3. The grafting parameters increased with increasing temperature up to 35°C, but thereafter, these parameters decreased. With increasing time period of reaction from 60 to 180 min, %G, %A, and %E increased up to 120 min, but thereafter, these parameters decreased. The graft copolymer was characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Study of the physical aging of the epoxy system BADGE n = 0/m‐XDA/CaCO3
Authors: Fraga F. , López M. , Soto Tellini V. H. , Rodríguez‐Núñez E. , Martínez‐Ageitos J. M. , Miragaya J. 
Published: April 2009

AbstractThe physical aging of the epoxy network consisting of a diglycidyl ether of bisphenol A (BADGE n = 0), m‐xylylenediamine (m‐XDA), and calcium carbonate was studied by differential scanning calorimetry. The glass transition temperature and the variation of the specific heat capacities were calculated using the method based on the intersection of both enthalpy–temperature lines for glassy and liquid states. The apparent activation energy was calculated using a single method that involved separate temperature and excess enthalpy dependency. All calorimetric data were compared with those obtained for the epoxy network without filled calcium carbonate. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
A smart hollow filament with thermal sensitive internal diameter
Authors: Meng Qinghao , Liu Jinlian , Shen Liming , Hu Yang , Han Jianping 
Published: April 2009

AbstractIn this work, a thermoplastic shape memory polyurethane was prepared via melt polymerization and a corresponding shape memory hollow fiber was fabricated via melt spinning. The fiber mechanical properties, especially shape memory effect, were characterized by static tensile, thermo‐mechanical cyclic tensile testing. The hollow fiber switching temperature was the melting transition temperature of the soft segment phase at about 41°C. The tenacity of the hollow fiber was about 1.14 cN/dtex, and breaking elongation was 682%. The shape fixity ratio was above 87% and the recovery ratio was above 89%. The internal diameter of the hollow fiber could be noticeably changed and the deformed fiber cross‐section could be well fixed. Once heated above the soft segment phase melting transition temperature, the hollow fiber internal hole recovered to its original diameter. The results from differential scanning calorimetry, X‐ray diffraction, and dynamic mechanical analysis were used to illustrate the mechanism governing the mechanical properties and shape memory effect especially. Due to the changes of the hollow fiber and the internal diameter affect of the physical properties of the prepared products, this fiber may be used in smart textiles for thermal management, or as stuffing of pillows and mattresses, which can adjust to body contours. Furthermore, the findings suggest that this kind of hollow fiber with thermal sensitive internal diameter could be used in smart filtration, drug‐controlled release, and liquid transportationin vivo. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Hydroxypropylation of cellulose isolated from bamboo (Dendrocalamus strictus) with respect to hydroxypropoxyl content and rheological behavior of the hydroxypropyl cellulose
Authors: Sharma Ritu , Varshney V. K. , Chauhan Ghanshyam S. , Naithani Sanjay , Soni P. L. 
Published: April 2009

AbstractBamboo, a lignocellulosic material, is a renewable source of interest as feedstock for production of cellulose derivatives by chemical functionalization. Optimization of hydroxypropylation of cellulosic material (average DP 816), isolated from bamboo (Dendrocalamus strictus) was, therefore, performed with respect to maximum percent hydroxylpropoxyl (% HP) contents under varying reaction conditions and studying their effect on the % HP. The optimized reaction conditions were aqueous NaOH concentration 22%, propylene oxide concentration 17.4 mol/AGU, temperature 50°C, duration of hydroxypropylation 4 h to yield hydroxypropyl cellulose of % HP 65.89. The ηapp of 1 and 2% solutions of the optimized product showed it to be non‐Newtonian pseudoplastic. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Soy‐based polyols from oxirane ring opening by alcoholysis reaction
Authors: Lozada Zuleica , Suppes Galen J. , Tu Yuan‐Chan , Hsieh Fu‐Hung 
Published: April 2009

AbstractA screening study was conducted to identify a catalyst that promotes epoxy ring opening of full epoxidized soybean oil (ESBO) avoiding side reactions at low concentration and temperature. Six catalysts different catalyst: formic acid, phosphoric acid, POLYCAT® 5, p‐toluenesulfonic acid monohydrate, POLYCAT® SA‐1, and DABCO® BL17 were evaluated in terms of acid number, oxirane oxygen content, and color analyses. p‐Toluenesulfonic acid shows a particular behavior that promotes the reaction resulting in a maximum oxirane oxygen content reduction; low acid number and color index compare to the others catalyst. To create an alkoxy hydroxy ESBO molecule, ESBO was combined with methanol and ethylene glycol using 0.5% by wt of p‐toluenesulfonic acid at 130, 150, and 170°C for different reaction times. Optimal conditions for oxirane ring opening by alcoholysis reaction were determined varying temperatures and reaction times. FTIR spectrum confirmed the emergence of hydroxyl groups in the alkoxy hydroxy ESBO polyol sample. The polyol sample G was characterized in terms of its hydroxyl number and its potential of replacing up from 50–100% of the petroleum‐based polyol in waterborne rigid polyurethane foam application. All polyurethanes foams were evaluated to determine their thermal conductivity, density, and compressive strength properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Dynamic responses of irregular fibers under axial tension
Authors: Yan Wenyi , Li Zhi , Wang Xungai , Wang Lijing 
Published: April 2009

AbstractA numerical study on the dynamic responses of irregular fibers under axial tension is presented in this article. The irregularity was represented by a sinusoidal shape profile along the fiber axis. The finite element method was used in the simulations and the maximum first principal stress due to the dynamic pulling has been examined. Our numerical results indicate that the first principal stress mainly varies along the longitudinal direction. Its change in radial direction is negligibly small. The maximum first principal stress in an irregular fiber always appears in the narrowest crosssection, which is the weakest link of the fiber. The maximum first principal stress is very sensitive to the change in the irregular amplitude. The stress value increases dramatically with the increase in the amplitude of irregularity. The frequency of irregularity has a limited effect on the maximum first principal stress. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Polymer dynamics in rubbery epoxy networks/polyhedral oligomeric silsesquioxanes nanocomposites
Authors: Kourkoutsaki Th. , Logakis E. , Kroutilova I. , Matejka L. , Nedbal J. , Pissis P. 
Published: April 2009

AbstractDielectric techniques, including thermally stimulated depolarization currents (TSDC, −150 to 30°C) and, mainly, broadband dielectric relaxation spectroscopy (DRS, 10−2 – 106 Hz, −150 to 150°C) were employed, next to differential scanning calorimetry (DSC), to investigate molecular dynamics in rubbery epoxy networks prepared from diglycidyl ether of Bisphenol A (DGEBA) and poly(oxypropylene)diamine (Jeffamine D2000, molecular mass 2000) and modified with polyhedral oligomeric silsesquioxanes (POSS) units covalently bound to the chains as dangling blocks. Four relaxations were detected and analyzed: in the order of increasing temperature at constant frequency, two local, secondary γ and β relaxations in the glassy state, the segmental α relaxation associated with the glass transition and the normal mode relaxation, related with the presence of a dipole moment component along the Jeffamine chain contour. Measurements on pure Jeffamine D2000 helped to clarify the molecular origin of the relaxations observed. A significant reduction of the magnitude and a slight acceleration of the α and of the normal mode relaxations were observed in the modified networks. These results suggest that a fraction of polymer is immobilized, probably at interfaces with POSS, due to constraints imposed by the covalently bound rigid nanoparticles, whereas the rest exhibits a slightly faster dynamics due to increaseof free volume resulting from loosened molecular packing of the chains (plasticization by the bulky POSS units).The increase of free volume is rationalized by density measurements. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Imidazolium‐organic solvent–alkali metal salt mixtures as nonflammable electrolytes incorporated into PVDF–PEG polymer electrolyte
Authors: Wang Yun‐Pu , Gao Xiang‐Hu , Chen Jiu‐Cun , Li Zhi‐Wen , Li Cheng‐Lin , Zhang Shou‐Cun 
Published: April 2009

AbstractA mixture of flammable organic solvent, alkali metal salt, and nonflammable room temperature ionic liquid has been used as a new type of electrolyte. A novel microporous polymer electrolyte based on poly(vinylidene fluoride), i.e., PVDF, and poly(ethylene glycol), i.e., PEG, was prepared by a simple phase‐inversion technique. The mixed electrolyte was observed to be nonflammable at ionic liquid contents of 60 vol % or greater. The viscosity (range, 0.98–30.5 mPa s) and conductivity (range, 9.9 to 22.25 mS cm−1) of the mixed electrolyte were discussed. The porosity, solution uptake, and conductivity mechanism of polymer membranes also were discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Fluconazole release through semi‐interpenetrating polymer network hydrogels based on chitosan, acrylic acid, and citraconic acid
Authors: Pulat Mehlika , Asıl Dilek 
Published: April 2009

AbstractSemi‐interpenetrating polymer network hydrogels with different compositions of chitosan (Cs), acrylic acid, and citraconic acid were synthesized via free‐radical polymerization with ethylene glycol dimethacrylate as a crosslinker. The variations of the swelling percentages of the hydrogels with time, temperature, and pH were determined, and Cs–poly(acrylic acid) (PAA) hydrogels were found to be most swollen at pH 7.4 and 37°C. Scanning electron micrographs of Cs–PAA and Cs–P(AA‐co‐CA)‐1 (Cs‐poly(acrylicacid‐co‐citraconir acid)−1) were taken to observe the morphological differences in the hydrogels. Although the less swollen hydrogel, Cs–P(AA‐co‐CA)‐1, had a sponge‐type structure, the most swollen hydrogel, Cs–PAA, displayed a uniform porous appearance. Fluconazole was entrapped in Cs–P(AA‐co‐CA)‐1 and Cs–PAA hydrogels, and the release was investigated at pH 4.0 and 37°C. The kinetic release parameters of the hydrogels (the gel characteristic constant and the swelling exponent) were calculated, and non‐Fickian diffusion was established for Cs–PAA, which released fluconazole much more slowly than the Cs–P(AA‐co‐CA)‐1 hydrogel. A therapeutic range was reached at close to 1 h for both hydrogels. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Electrospun polylactide/silk fibroin–gelatin composite tubular scaffolds for small‐diameter tissue engineering blood vessels
Authors: Wang Shudong , Zhang Youzhu , Yin Guibo , Wang Hongwei , Dong Zhihui 
Published: April 2009

AbstractMany synthetic scaffolds have been used as vascular substitutes for clinical use. However, many of these scaffolds may not show suitable properties when they are exposed to physiologic vascular environments, and they may fail eventually because of some unexpected conditions. Electrospinning technology offers the potential for controlling the composition, structure, and mechanical properties of scaffolds. In this study, a tubular scaffold (inner diameter = 4.5 mm) composed of a polylactide (PLA) fiber outside layer and a silk fibroin (SF)–gelatin fiber inner layer (PLA/SF–gelatin) was fabricated by electrospinning. The morphological, biomechanical, and biological properties of the composite scaffold were examined. The PLA/SF–gelatin composite tubular scaffold possessed a porous structure; the porosity of the scaffold reached 82 ± 2%. The composite scaffold achieved the appropriate breaking strength (1.28 ± 0.21 MPa) and adequate pliability (elasticity up to 41.11 ± 2.17% strain) and possessed a fine suture retention strength (1.07 ± 0.07 N). The burst pressure of the composite scaffold was 111.4 ± 2.6 kPa, which was much higher than the native vessels. A mitochondrial metabolic assay and scanning electron microscopy observations indicated that both 3T3 mouse fibroblasts and human umbilical vein endothelial cells grew and proliferated well on the composite scaffold in vitro after they were cultured for some days. The PLA/SF–gelatin composite tubular scaffolds presented appropriate characteristics to be considered as candidate scaffolds for blood vessel tissue engineering. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009