bluuebunny/crossref_metadata_2025_split huggingface dataset:
A meal on the hoof or wealth in the kraal? Stable isotopes at Kgaswe and Taukome in eastern Botswana
Authors: Murphy Kimmarie A. 
Published: April 2010

AbstractIron Age sites associated with the Toutswe tradition in Eastern Botswana date between CE 700–1300 and share a variety of settlement patterns, economic features and material culture. The presence of domestic fauna, settlement structures and concentrations of vitrified dung provide archaeological evidence for herding economies. However, due to factors of preservation and past retrieval techniques, evidence for plant remains is still somewhat limited for the Toutswe sites in Botswana. Additionally, archaeological remains such as flora, fauna and material culture often provide only indirect evidence for their contributions to diet. This study provides new evidence for the diet of individuals from the Toutswe tradition. Given the large numbers of animal remains and residues at Toutswe sites, the expectation is that animal domesticates were also an integral part of the diet. Stable isotopic analysis of human remains indicates that even though domestic cattle and sheep occur in great abundance at Toutswe sites, their contribution to the diet may be minimal. The main source of protein for individuals at Kgaswe and Taukome comes from C4 plants such as sorghum and millet and to a lesser extent, animal products. The practice of maintaining large domestic herds for economic and social reasons rather than for primary subsistence in southern Africa today may have its roots in the Iron Age populations of the region. Copyright © 2010 John Wiley & Sons, Ltd.
Synthesis of functionalized conducting polymer “polyanthranilic acid” using various oxidizing agents and formation of composites with PVC
Authors: Gupta Bhavana , Prakash Rajiv 
Published: April 2010

AbstractSynthesis of carboxyl functionalized polyaniline (PANI) (polyanthranilic acid PANA) is reported based on our recent studies using various oxidizing agents. PANA was synthesized in acidic medium using ammonium peroxodisulfate, hydrogen peroxide, and potassium permanganate as oxidizing agents and their structural, electrochemical, and electrical properties are studied. A comparative study among the polymers formed by various oxidizing agents and also with PANI is made. Various possible oxidation states of PANA are discussed, with the help of electrochemical data. A composite of PANA and polyvinyl chloride (PVC) containing 20% PVC by weight is synthesized and used for the development of solid state pH electrode. The composite was synthesized to improve mechanical strength, stability, and restrict solubility. The pH sensor response is found to be reversible and linear in the pH range 1–7. PANA and PVC (20 wt%) based pH sensors show potential applications in development of pH transducers based sensors/biosensors. Copyright © 2010 John Wiley & Sons, Ltd.
Chitin/polyurethane blends: a thermal and morphological study
Authors: Matsui Mitsuka , Munaro Marilda , Akcelrud Leni 
Published: April 2010

AbstractChitin is an abundant natural polymer having important properties such as biocompatibility and biodegradability combined with healing capability. Its use in biomedical applications has been hindered by its poor processing properties such as low solubility and stiffness in the solid state. In an attempt to obtain flexible and more processable chitin‐based materials, we prepared blends of the polymer with a polyurethane containing a soft segment based on biodegradable polycaprolactone. A certain degree of miscibility was found between chitin and the polyurethane, as demonstrated by a shift in the glass transition of the polyurethane observed in dynamical mechanical analyses, with a simultaneous decrease in crystallinity of chitin observed in X‐ray diffraction analyses. A phase inversion of the blends took place for a 50/50 (w/w) composition ratio as demonstrated from thermal, dynamic mechanical, tensile and X‐ray diffraction measurements. Blends of chitin with the polycaprolactone‐based polyurethane can be effectively used to produce tough materials useful in biomedical applications. The mechanical strength of the blends demonstrated that they are able to support tensions above those required for bone replacement, making them good candidates for that purpose. Copyright © 2010 Society of Chemical Industry
Controllable preparation of epoxy‐functionalized magnetic polymer latexes with different morphologies by modified miniemulsion polymerization
Authors: Xu Yawen , Xu Hong , Gu Hongchen 
Published: April 2010

AbstractThe synthesis of functional magnetic polymer latexes (MPLs) with epoxy groups introduced via a modified miniemulsion polymerization route was described. The epoxy group content on the surface could be controlled by seed emulsion followed and characterized by FTIR and zeta potential measurements. We also developed a novel approach to achieve manipulation of the morphology of the MPLs based on kinetic control of the polymerization system. MPLs with different morphologies were obtained ranging from core–shell microstructures, dispersed microstructures to asymmetric microstructure, which were characterized by TEM, DLS, and TGA. The mechanisms of the contribution of kinetic factors such as polymerization rate, reaction time, and temperature contributing to the formation of the different morphologies were also investigated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2284–2293, 2010
Thermoresponsive brush copolymers with poly(propylene oxide‐ran‐ethylene oxide) side chains via metal‐free anionic polymerization “grafting from” technique
Authors: Zhao Junpeng , Zhang Guangzhao , Pispas Stergios 
Published: April 2010

AbstractThermoresponsive brush copolymers with poly(propylene oxide‐ran‐ethylene oxide) side chains were synthesized via a “grafting from” technique. Poly(p‐hydroxystyrene) was used as the backbone, and the brush copolymers were prepared by random copolymerization of mixtures of oxyalkylene monomers, using metal‐free anionic ring‐opening polymerization, with the phosphazene base (t‐BuP4) being the polymerization promoter. By controlling the monomer feed ratios in the graft copolymerization, two samples with the same side‐chain length and different compositions were prepared, both of which possessed high molecular weights and low molecular weight distributions. The results from light scattering and fluorescence spectroscopy indicated that the brush copolymers in their dilute aqueous solutions were near completely solvated at low temperature and underwent slight intramolecular chain contraction/association and much more profound intermolecular aggregation at different stages of the step‐by‐step heating process. Above 50 °C, very turbid solutions, followed by macrophase separation, were observed for both of the samples, which implied that it was difficult for the brush copolymers to form stable nanoscopic aggregates at high temperature. All these observations were attributed, at least partly, to the distribution of the oxyalkylene monomers along the side chains and the overall brush‐like molecular architecture. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2320–2328, 2010
New thiophene‐phenylene‐thiophene acceptor random conjugated copolymers for optoelectronic applications
Authors: Tsai Jung‐Hsun , Chueh Chu‐Chen , Chen Wen‐Chang , Yu Chao‐Ying , Hwang Gue‐Wuu , Ting Ching , Chen En‐Chen , Meng Hsin‐Fei 
Published: April 2010

AbstractNew low band gap thiophene‐phenylene‐thiophene (TPT)‐based donor‐acceptor‐donor random copolymers were synthesized for optoelectronic device applications by a palladium‐catalyzed Stille coupling reaction under microwave heating. The acceptors included 2,3‐bis(4‐(2‐ethylhexyloxy)phenyl)‐5,8‐bis[5′‐bromo‐dithien‐2‐yl‐quinoxalines] (DTQ) and 3,6‐bis(5‐bromothiophen‐2‐yl)‐2,5‐bis(2‐ethyl‐hexyl)‐pyrrolo[3,4‐c]‐pyrrole‐1,4‐dione (DPP). The prepared random copolymers were named as PTPTDTQ0.55, PTPTDTQ0.34DPP0.14, and PTPTDTQ0.26DPP0.34 depending on the copolymer ratio. The optical band gaps (E) of PTPTDTQ0.55, PTPTDTQ0.34DPP0.14, and PTPTDTQ0.26DPP0.34 were 1.74, 1.56, and 1.48 eV, respectively. The hole mobility obtained from the field‐effect transistor devices prepared from PTPTDTQ0.55, PTPTDTQ0.34DPP0.14, and PTPTDTQ0.26DPP0.34 were 2.2 × 10−3, 2.4 × 10−3, and 4.7 × 10−3 cm2 V−1 s−1, respectively, with the on‐off ratios of 4.0 × 104, 4.0 × 104, and 5.3 × 104. It suggested that the significant intramolecular charge transfer between the TPT and acceptor led to the band gap reduction and hole mobility enhancement. Polymer solar cells of these TPT‐based copolymers blended with 1‐(3‐methoxycarbonyl)propyl‐1‐phenyl‐[6,6]‐C‐71 (PC71BM) under illumination of AM 1.5G (100 mW cm−2) solar simulator exhibited a power conversion efficiency (PCE) as high as 3.71%. Besides, the near‐infrared photodetector device prepared from PTPTDTQ0.26DPP0.34 showed a high external quantum efficiency exceeding 32% at 700 nm (under −3 V bias) and fast‐speed response. This study suggests that the prepared TPT‐based donor‐acceptor random copolymers exhibited promising and versatile applications on optoelectronic devices. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2351–2360, 2010
Polyisobutylene‐based polyurethanes. VI. Unprecedented combination of mechanical properties and oxidative/hydrolytic stability by H‐bond acceptor chain extenders
Authors: Erdodi Gabor , Kang Jungmee , Kennedy Joseph P. 
Published: April 2010

AbstractWe describe the design, synthesis, characterization, and testing of novel polyurethanes (PUs) exhibiting unprecedented combinations of outstanding mechanical properties and oxidative/hydrolytic stabilities. This achievement is due to the use of polyisobutylene (PIB) soft segments plus flexible H‐bond acceptor chain extenders (HACEs): the PIB imparts superior oxidative/hydrolytic stability and the HACE produces reinforcing H‐bonds, which lead to outstanding mechanicals. Oxidative/hydrolytic stability was quantitated by retention of tensile strength and elongation after exposure to nitric acid. PUs containing 60–70% PIB retain their mechanical properties, whereas Carbothane®, Bionate®, and Elast‐Eon™, PUs marketed for chemical stability, degrade severely under the same conditions. Various HACEs were identified (e.g., hexaethylene glycol, tripropylene glycol, tributylene glycol, 3,3′‐diamino‐N‐methyl‐dipropylamine, etc.) and their effect on mechanical properties was investigated. A PIB‐ and HACE‐containing PU exhibited 29.2 MPa tensile strength, 620% elongation, and 80 Shore A hardness. Properties were analyzed in terms of stress–strain profiles, differential scanning calorimetry traces, dynamic mechanical thermal analysis plots, and oxidative/hydrolytic stability. The properties of various PIB‐based rubbers, that is, thermoplastic PUs, SIBSTAR®, and thermoset butyl rubber are compared. The novel PUs are promising candidates for biomaterials and industrial applications where a combination of mechanical properties and oxidative/hydrolytic stability is of the essence. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2361–2371, 2010
Photopolymerization of poly(ethylene glycol) dimethacrylates: The influence of ionic liquids on the formulation and the properties of the resultant polymer materials
Authors: Chesnokov Sergey A. , Zakharina Marya Yu. , Shaplov Alexander S. , Lozinskaya Elena I. , Malyshkina Inna A. , Abakumov Gleb A. , Vidal Frederic , Vygodskii Yakov S. 
Published: April 2010

AbstractThe photo‐initiated polymerization of poly(ethylene glycol)dimethacrylates [PEGDM(n)] in the presence of various ionic liquids (ILs) is reported. The influence of ILs concentrations as well as of their nature upon the photopolymerization kinetics was studied in detail. It was found that according to reactive ability in bulk and in solution photopolymerization, the investigated monomers can be divided into two groups: PEGDM(1)–PEGDM(2)–PEGDM(3) and PEGDM(4)–PEGDM(7‐8). ILs slightly influence the photopolymerization of monomers from the first group and greatly change kinetics of those from the second. Such behavior was explained by the theory of “kinetically favorable or unfavorable monomer associations.” It was demonstrated that certain ILs accelerate the photopolymerization of the highest PEGDMs and offer access to the polymers derived from low reactive monomers. Relying on the obtained data, the attempt to predict the structure of the “best” ionic additive for the given monomer photopolymerization was performed and proved. Finally, the influence of both residual and specially added ILs quantities upon the properties of obtained polymer materials was investigated. It was revealed that ILs can physically interact with polymer networks increasing their thermal stability, plasticizing films, and blocks, imparting ionic conductivity equal up to 3.62 × 10−3 Sm/cm at 25 °C. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2388–2409, 2010
Bioinspired polymer functionalized with a diiron carbonyl model complex and its assembly onto the surface of a gold electrode via “click” chemistry
Authors: Ru Xiang , Zeng Xianghua , Li Zhimei , J. Evans David , Zhan Caixia , Tang Ying , Wang Lianjie , Liu Xiaoming 
Published: April 2010

AbstractA complex pendant with two ethynyl groups, [Fe2(μ‐SCH2CCH)2(CO)6] (2), as a model of the diiron subunit of [FeFe]‐hydrogenase was polymerized and the {Fe2(CO)6} core was successfully incorporated into the polymer matrix. The polymer was characterized by a variety of spectroscopic techniques, TGA, FTIR, SEM, TEM, and NMR. The resultant polymer was immobilized via “click” chemistry using its terminal CCH bond onto the surface of a gold electrode, which was premodified with azidothiol by self‐assembled monolayer (SAM). The assembled electrode showed electrochemical responses. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2410–2417, 2010
One‐pot synthesis of well‐defined multiblock polymer: Combination of ATRP and RAFT polymerization involving cyclic trithiocarbonate
Authors: Wu Yusong , Wang Qi 
Published: April 2010

AbstractMultiblock polymers were prepared by combination of ATRP (CuBr/tris[(2‐pyridyl)methyl]amine) and RAFT polymerization involving cyclic trithiocarbonate (CTTC). In the combined polymerization system, the ATRP was introduced as constant radical source, CTTC underwent ring‐opening polymerization, and the incorporated trithiocarbonate moieties derived from CTTCs performed as RAFT agent. Through the integrated process, multiblock polymers containing predictable average block number together with controlled molecular weight of the blocks were prepared by one‐pot polymerization. The average block number of polymer was controlled by concentration ratio of CTTC to alkyl halide in ARTP, and the molecular weight of block were well regulated by concentration of CTTC and monomer conversion. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2425–2429, 2010
Facile, one‐pot synthesis of aromatic diamine‐based benzoxazines and their advantages over diamines as epoxy hardeners
Authors: Chang Sheng Lung , Lin Ching Hsuan 
Published: April 2010

AbstractThree aromatic diamine‐based benzoxazines were successfully prepared by a facile, clean, one‐pot procedure from 1,4‐phenylenediamine (1), 4,4′‐diaminodiphenyl ether (2), and 4,4′‐diaminodiphenyl methane (3), respectively. Their structures were confirmed by NMR spectra and single crystal diffractogram. The effect of the reactivity of diamines on the purity of the resultant benzoxazines was discussed. The resultant benzoxazines were applied as hardeners for cresol novolac epoxy (CNE). The processing window, the latent curing characteristic, and the miscibility of benzoxazine/CNE systems were discussed. Compared with diamines (1 and 3), (1 and 3)‐based benzoxazines show latent curing characteristic as epoxy hardeners, and wide processing windows can be obtained. Compared with diamine (2) which is immiscible with CNE in the molten state, (2)‐based benzoxazine shows good miscibility with CNE. Dynamic mechanical analysis shows the Tgs of the benzoxazine/CNE thermosets are as high as 242–243 °C. Thermogravimetric analysis shows the outstanding thermal stability of the resultant thermosets. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2430–2437, 2010
Overcoming the oxygen inhibition in the photopolymerization of acrylates: A study of the beneficial effect of triphenylphosphine
Authors: Belon C. , Allonas X. , Croutxé‐barghorn C. , Lalevée J. 
Published: April 2010

AbstractTriphenylphosphine (TPP) was used in free‐radical UV‐curable resins to reduce oxygen inhibition effect. The relative influence of concentration, monomer viscosity, light intensity and sample thickness on TPP efficiency was investigated by real time infrared spectroscopy. It is shown that TPP is an effective oxygen scavenger. The mechanism was investigated by means of Laser Flash Photolysis. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2462–2469, 2010
Solving the loss of orthogonality during the polyaddition of α‐azide‐ω‐alkyne monomers catalyzed by Cu(PPh3)3Br: Application to the synthesis of high‐molar mass polytriazoles
Authors: Binauld Sandra , Fleury Etienne , Drockenmuller Eric 
Published: April 2010

AbstractPolyaddition of an α‐azide‐ω‐alkyne monomer by Cu(PPh3)3Br catalyzed 1,3‐dipolar cycloaddition was thoroughly studied as a model system to investigate the orthogonality of this click chemistry process. Indeed, loss of chain‐end functionality and occurrence of side reactions have a tremendous impact on the molar mass of polymers obtained by step growth polymerization. Particularly, SEC, 1H, and 31P NMR experiments have highlighted the occurrence of a Staudinger side‐reaction between azide chain‐ends and PPh3 from the copper(I) catalyst that dramatically alters Mn of the resulting polytriazoles. A significant enhancement of Mn could be achieved by using an alternative catalyst and optimized experimental conditions, that is, dilution and reaction time. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2470–2476, 2010
Antibiotics for uncomplicated urinary tract infection in women
Authors: Thompson Sarah , Yacomeni Sarah , Townsend Robert 
Published: April 2010

AbstractMost well women with uncomplicated urinary tract infection should respond to three days' treatment with a first‐line antibiotic. Our Drug review describes the properties and side‐effects of the recommended antibiotics, followed by sources of further information. Copyright © 2010 Wiley Interface Ltd
An analysis of transient thermal properties for high power GaN‐based laser diodes
Authors: Kim Jae Min , Kim Seungtaek , Kang Sung Bok , Kim Young Jin , Jeong Hoon , Lee Kyeongkyun , Kim Jongseok , Lee Sangdon , Suh Dongsik , Yi Jeong Hoon , Choi Yoonho , Jung Seok Gu , Noh Minsoo 
Published: April 2010

AbstractThermal properties of 405 nm GaN‐based laser diodes were investigated by employing a transient heating response method based on the temperature dependence of diode forward voltage. Thermal resistances of materials consisting of packaged laser diodes were differentiated in transient thermal response curves at a current below threshold current. With a current above threshold current, no significant change in thermal resistances and difference between junction‐up and junction‐down laser diodes was observed at pulses shorter than 3 sec. From an analysis with long current injections, thermal resistance of a packaged laser diode with a junction‐up bonding was ∼45 °C/W which was higher than that of a junction‐down bonded laser diode by ∼10 °C/W. Further analyses based on parameters obtained from voltage recovery curves indicated that the time constant for cooling is directly related to the thermal resistance and thermal capacitance of a laser diode package. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaN based nanorod light emitting diodes by selective area epitaxy
Authors: Zang Keyan , Chua Soo Jin 
Published: April 2010

AbstractSite‐controlled, vertically aligned gallium nitride nanorod light emitting diode (LEDs) arrays with high aspect ratio have been synthesized via catalyst‐free metalorganic chemical vapor deposition. Nanorod LEDs arrays with ∼1 μm in length and ∼200 nm in diameter were prepared on n‐type gallium nitride film on sapphire substrates using nanoporous silicon dioxide as a growth mask patterned by anodized aluminum oxide. GaN nanorod LEDs demonstrate a higher photoluminescence in intensity, compared to that of a planar GaN. This is contributed to the improvement of light extraction due to the faceted nanostructures and the improvement in crystal quality. In addition, more Indium incorporation has been demonstrated compared to the control LEDs structure. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaN surface nanostructure photodetector based on back side incidence
Authors: Zhang Jing , Naoi Yoshiki , Sakai Shiro , Fukano Atsuyuki , Tanaka Satoru 
Published: April 2010

AbstractThe conventional photodetector can detect the intensity of the incident light by the voltage or current, but it is not sensitive to the change of the incident angle or wavelength. A GaN‐based photodetector with nanostructure on the surface has been fabricated using nanoimprint lithography (NIL). The photovoltage between p‐ and n‐layers of the surface nanostructure photodetector took 6 or 12 periods when the incident illumination angles were changed on the back side. According to the characteristics, this type of photodetector can find out the change of the incidence angle or the change of the wavelength of the incident light. The short wave absorption disturbance can be avoided when the light illuminating based on the back side. Therefore, the stability of detection can be improved and the requirement of work environment is reduced. In addition, the generation principles of periodic photovoltage are different between the light illuminating based on the back side and the surface. Thus, the surface nanostructure photodetector can be used in wider fields. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of doping on optical properties of catalyst‐ and mask‐free grown gallium nitride nanorods
Authors: Kalden J. , Sebald K. , Kunert G. , Aschenbrenner T. , Kruse C. , Hommel D. , Gutowski J. 
Published: April 2010

AbstractWe present a comparison of the optical properties of Si and Mg doped GaN nanorods with respect to an undoped sample. The reference sample is characterized by a high crystalline quality as indicated by the spectral width of the dominant emission peaks being comparable for the ensemble and single nanorods as well as by the absence of the yellow photoluminescence. Even after the incorporation of n‐dopants this defect related emission band is still not detectable.The p‐doped sample shows several modifications of the spectrum. The near band edge emission is dominated by an additional band at 3.41 eV related to partial coalescence of the nanorods, while the excitonic emission is very weak. The DAP band emission is obviously evolved into a double band series with two zero‐phonon peaks at 3.26 eV and 3.18 eV indicating the involvement of two acceptor related states, and is further superimposed by a weak yellow luminescence band around 2.5 eV. These results are important as basis for applications of such nanorods as electrically driven semiconductor devices with excellent crystalline quality as well as with very high surface sensitivity, which is useful for solar cells or chemical sensors, for example. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)