bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanocomposite prepared from in situ grafting of polypyrrole to aminobenzoyl‐functionalized multiwalled carbon nanotube and its electrochemical properties
Authors: Jeon In‐Yup , Choi Hyun‐Jung , Tan Loon‐Seng , Baek Jong‐Beom 
Published: April 2011

AbstractWe reported the functionalization of multiwalled carbon nanotube (MWCNT) with 4‐aminobenzoic acid by a “direct” Friedel–Crafts acylation reaction in a mild polyphosphoric acid (PPA)/phosphorous pentoxide (P2O5) medium. The resulting 4‐aminobenzoyl‐functionalized MWCNT (AF‐MWCNT) was used as a platform for the grafting of polypyrrole (PPy) in ammonium persulfate (APS)/aqueous hydrochloric acid solution to produce PPy‐grafted MWCNT (PPy‐g‐MWCNT) composite. After dedoping with alkaline treatment, PPy‐g‐MWCNT displayed 20 times higher electrical conductivity than that of PPy. The current density and cycle stability of PPy‐g‐MWCNT composite were also remarkably improved compared with those of PPy homopolymer, suggesting that an efficient electron transfer between PPy and MWCNT was possible through covalent links. In addition, PPy‐g‐MWCNT displayed high electrocatalytic activity for oxygen reduction reaction (ORR). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Synthesis and two‐photon absorption properties of conjugated polymers with N‐arylpyrrole as conjugated bridge and isolation moieties
Authors: Li Qianqian , Huang Jing , Pei Zhiguo , Zhong Aoshu , Peng Ming , Liu Jun , Huang Zhenli , Qin Jingui , Li Zhen 
Published: April 2011

AbstractThree novel conjugated polymers with N‐arylpyrrole as the conjugated bridge were designed and synthesized, which emitted strong one‐ or two‐photon excitation fluorescence in dilute tetrahydrofuran (THF) solution with high quantum yields. The maximal two‐photon absorption (TPA) cross‐sections of the polymers, measured by the two‐photon‐induced fluorescence method using femtosecond laser pulses in THF, were 752, 1114, and 1869 GM, respectively, indicating that the insertion of electron‐donating or electron‐withdrawing moieties into the polymer backbone could benefit to the increase of the TPA cross‐section. Their large TPA cross‐sections, coupled with the relatively high emission quantum yields, made these conjugated polymers attractive for practical applications, especially two‐photon excited fluorescence. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Dendritic surface functionalization of biodegradable polymer assemblies
Authors: Nazemi Ali , Amos Ryan C. , Bonduelle Colin V. , Gillies Elizabeth R. 
Published: April 2011

AbstractThe functionalization of nanomaterials with dendritic surface moieties was recently demonstrated to be an effective means of displaying biological ligands and potentially modulating the biological properties of these materials. With the aim of extending this surface functionalization approach to biodegradable polymer assemblies, poly(ethylene oxide)‐polycaprolactone (PEO‐PCL) block copolymers with terminal azide or methoxy groups were prepared and were assembled to form micelles or vesicles with varying loadings of surface azides. Dendrons bearing peripheral amines, guanidines, or hydroxyls were prepared and conjugated to the assemblies, and the conjugation yields were measured and compared as a function of azide loading and assembly type (micelle versus vesicle). A small molecule rhodamine derivative was also conjugated, allowing the effect of sterics to be studied. The effects of the surface functionalization on the aggregation state of the assemblies were studied by light scattering and transmission electron microscopy. Overall, the results revealed interesting differences between the two systems with respect to both the reaction yields and the stabilities. Furthermore, micelles functionalized with dendrons bearing peripheral guanidines were found to exhibit enhanced cell uptake relative to control micelles, demonstrating that this approach can be used to modulate the biological properties of the materials. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Elucidating the reaction mechanism of the benzoate oxidation pathway encoded aldehyde dehydrogenase from Burkholderia xenovorans LB400
Authors: Bains Jasleen , Leon Rafael , Temke Kevin G. , Boulanger Martin J. 
Published: April 2011

AbstractOxidation of cis‐3,4‐dehydroadipyl‐CoA semialdehyde to cis‐3,4‐dehydroadipyl‐CoA by the aldehyde dehydrogenase, ALDHC (EC.1.2.1.77), is an essential step in the metabolism of benzoate in Burkholderia xenovorans LB400. In a previous study, we established a structural blueprint for this novel group of ALDH enzymes. Here, we build significantly on this initial work and propose a detailed reaction mechanism for ALDHC based on comprehensive structural and functional investigations of active site residues. Kinetic analyses reveal essential roles for C296 as the nucleophile and E257 as the associated general base. Structural analyses of E257Q and C296A variants suggest a dynamic charge repulsion relationship between E257 and C296 that contributes to the inherent flexibility of E257 in the native enzyme, which is further regulated by E496 and E167. A proton relay network anchored by E496 and supported by E167 and K168 serves to reset E257 for the second catalytic step. We also propose that E167, which is unique to ALDHC and its homologs, serves a critical role in presenting the catalytic water to the newly reset E257 such that the enzyme can proceed with deacylation and product release. Collectively, the reaction mechanism proposed for ALDHC promotes a greater understanding of these novel ALDH enzymes, the ALDH super‐family in general, and benzoate degradation in B. xenovorans LB400.
Field trial measuring the compatibility of methoxyfenozide and flonicamid with Orius laevigatus Fieber (Hemiptera: Anthocoridae) and Amblyseius swirskii (Athias‐Henriot) (Acari: Phytoseiidae) in a commercial pepper greenhouse
Authors: Colomer Ignacio , Aguado Pedro , Medina Pilar , Heredia Rosa María , Fereres Alberto , Belda José Eduardo , Viñuela Elisa 
Published: April 2011

AbstractBACKGROUND: Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) and Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) are among the most serious pests of sweet peppers in greenhouses. Chemical control is difficult because of their high reproductive rates and insecticide resistance, and seasonal inoculative releases of Orius laevigatus (Fieber) and Amblyseius swirskii (Athias‐Henriot) are commonly used to reduce their populations. As chemical treatments are often needed in the crop against other pests, the side effects of methoxyfenozide (an insect growth regulator against lepidopteran pests) and flonicamid (a selective feeding inhibitor against sucking insects) were studied in both beneficial organisms in a commercial greenhouse.RESULTS: Orius laevigatus and A. swirskii were released at commercial rates (4–5 and 100 m−2), and a strong establishment and a very homogeneous distribution were reached. One pesticide treatment with the maximum field recommended concentration of methoxyfenozide and flonicamid (96 and 100 mg AI L−1) was done when they were well established, and their population levels were not affected either immediately or up to 30 days after treatment.CONCLUSION: The results are indicative of no impact of methoxyfenozide and flonicamid on the two natural enemies in the field, and both can be considered as potential alternatives to be included in IPM programmes in sweet pepper. Copyright © 2011 Society of Chemical Industry
Protective effect of recombinant human glucagon‐like peptide‐1 (rhGLP‐1) pretreatment in STZ‐induced diabetic mice
Authors: Wu Ye‐Lin , Huang Jing , Liu Jian , Jin Ming‐Fei , Gu Mei , Hong Yiguo , Wu Zi‐Rong 
Published: April 2011

AbstractHuman glucagon‐like peptide‐1 (hGLP‐1) and its mimetics have emerged as therapies for type 2 diabetes. However, clinical treatment of diabetes with hGLP‐1 is ineffective because of rapid DPPIV‐mediated hGLP‐1 degradation in the circulation. In this study, we investigated the protective effect of recombinant human glucagon‐like peptide‐1 (rhGLP‐1) treatment on STZ‐induced diabetic mice. Mice were treated daily with rhGLP‐1 (24 nmol/kg body weight) starting before or after STZ injection (40 mg/kg body weight) to induce diabetes. Mice pretreated with rhGLP‐1 before but not after STZ showed significantly reduced blood glucose levels (P < 0.05), increased oral glucose tolerance (area under the curve, 1740 ± 71.18 vs 2416 ± 205.6, P < 0.05). Furthermore, the bioproduct of lipid peroxidation, MDA, was reduced and SOD and GSH‐PX activities were enhanced globally and in pancreas of mice that received rhGLP‐1 pretreatment before STZ, when comparing with STZ‐treated mice. Finally, STZ‐induced pancreatic islet damage was rescued by rhGLP‐1 pretreatment. Taken together, the results of this study demonstrate that rhGLP‐1 pretreatment has a protective effect against STZ‐induced diabetes in mice. These findings suggest that the GLP‐1 pretreatment may be a new therapeutic strategy in the preventive and protective treatment during diabetes initiation and progression. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.
Synthesis and biological evaluation of analogues of the marine cyclic depsipeptide obyanamide
Authors: Zhang Wei , Ding Ning , Li Yingxia 
Published: April 2011

AbstractOn the basis of the total synthesis of obyanamide, 20 analogues of this marine cyclic depsipeptide have been synthesized by (i) preparation of the tripeptide fragments in the western hemisphere using Z/OtBu protocol; (ii) preparation of the dipeptide fragments in the eastern hemisphere using Boc/OMe protocol; and (iii) fragments coupling, removal of protecting groups (Boc and OtBu, in one pot), and macrocyclizaion in the last step. The cytotoxic test showed that three synthetic compounds exhibited moderate activities against HL‐60, KB, LOVO, and A549 cell lines. According to the results, the β‐amino acid residue was found to play a critical role in the biological activities. Additionally, the ester bond along with the Ala(Thz) moiety was also essential for biological activities. However, it seems too early to draw a conclusion that the N‐methylation of Val/Phe can lead to higher or lower cytotoxic activities. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.
A fundamental requirement for crystal‐field parametrization
Authors: Mulak Jacek , Mulak Maciej 
Published: April 2011

AbstractThe physically correct parametrization of the energy levels of transition ions in crystals in terms of crystal‐field (CF) Hamiltonians ${\cal H}_{{\rm CF}} = \sum\nolimits_{k} {} \sum\nolimits_{q} {} B_{kq} C_{q}^{(k)} $ has to be based on the CF parameters Bkq that lead to the correct CF splitting second moments, both the global one σ and the partial ones σk. Only such parametrizations correspond to the appropriate multipolar structure of the surrounding CF. Each parametrization being characterized by its own multipolar CF strengths $S_{k} = [1/(2k + 1)\sum\nolimits_{q} {|B_{kq} |^{2} } ]^{1/2} $, for k = 2, 4, and 6, yields a definite second moment σ, which can be derived from the additivity relationship $\sigma {}^{2} = \sum\nolimits_{k} {} \sigma _{k}^{2} = 1/(2J + 1)\sum\nolimits_{k} {S_{k}^{2} (\langle J||C^{(k)} ||J\rangle )^{2} } $, and the known asphericities $\langle \Psi ||C^{(k)} ||\Psi \rangle $ of the central‐ion eigenfunctions Ψ. The condition σ = σexp must be satisfied to ensure the parametrization's correctness. However, our survey of literature indicates that there exists many other well‐fitted CF parameter sets that do not obey this condition. Therefore, such sets are erratic and non‐physical, and should be re‐examined or rejected. Having σ for several (≥3) eigenstates $|\Psi \rangle $ along with the relevant $\langle \Psi ||C^{(k)} ||\Psi \rangle $ asphericities, one can estimate σk and Sk, which are well founded experimentally. The above findings set up the parametrization process properly. Lack of consistency between the second moments representing various parametrizations and the pertinent second moments observed in experiments is presumably the main reason for deluge of formally accurate but accidental and inequivalent parametrizations.
Elastic properties and inter‐atomic bonding in layered Fe–Cu arsenide oxide Sr2Fe2CuAs2O2
Authors: Shein Igor R. , Bannikov Vyacheslav V. , Ivanovskii Alexander L. 
Published: April 2011

AbstractInspired by recent discovery of the layered five‐component phase – the tetragonal arsenide oxide Sr2Fe2CuAs2O2uniting two types of [Fe2As2] and [CuO2] blocks, which are the main building blocks inherent in two basic families of high‐TCsuperconductors: so‐called cuprates and iron‐pnictides, we used the first principles calculations to predict the elastic properties and to find their interplay with inter‐atomic bonding for this unique system. Our data reveal that the examined phase is a relatively soft material; the predicted bulk and shear modules are about 90 and 54 GPa, respectively. Besides, this system is mechanically stable, adopts considerable elastic anisotropy, and should demonstrate brittleness. These conclusions agree with the bonding picture for Sr2Fe2CuAs2O2, according to which the inter‐atomic bonding in this system is highly anisotropic and includes ionic, covalent, and metallic contributions, where inside [Fe2As2] and [CuO2] blocks covalent‐ionic Fe–As, Cu–O and metallic‐like Fe–Fe bonds take place, whereas inter‐blocks bonding is basically of the ionic type.
Modeling magnetism of hexagonal Fe monolayers on 4d substrates
Authors: Al‐Zubi A. , Bihlmayer G. , Blügel S. 
Published: April 2011

AbstractMapping the total energies obtained from first principles calculations to model Hamiltonians is a powerful technique to explore the magnetic ground state of a system. We analyze the applicability of this approach in the presence of highly polarizable substrates, e.g. for an ultrathin Fe layer on Pd(111), Rh(111), Ru(0001), or Tc(0001). We find that the traditionally accepted model Hamiltonians (Heisenberg plus nearest neighbor higher‐order spin Hamiltonians) are not sufficient to capture the magnetic interactions in these systems and examine new terms that can be included to improve the description. Challenges for this technique are exemplified by the double‐rowwise antiferromagnetic (AFM) ground state predicted for Fe/Rh(111).
Non‐linear magnetoelastic coupling in monolayers: Experimental challenges and theoretical insights
Authors: Sander Dirk , Kirschner Jürgen 
Published: April 2011

AbstractRecent results of experimental studies on magnetoelastic coupling in epitaxial monolayers are compiled and discussed in view of theoretical work. The observation of non‐bulk like magnetoelastic coupling in strained systems in experiment and theory is ascribed to an effective and strain‐dependent magnetoelastic coupling. It is described as a second‐order strain contribution to the energy density. We comment on the importance of inhomogeneous strain and of its relaxation for the magnetic anisotropy of nanostructures.
Mn3−xGa (0 ≤ x ≤ 1): Multifunctional thin film materials for spintronics and magnetic recording
Authors: Kurt H. , Rode K. , Venkatesan M. , Stamenov P. , Coey J. M. D. 
Published: April 2011

AbstractTetragonal Mn3−xGa (0 ≤ x ≤ 1) epitaxial films possess exceptional magnetic and electronic properties. Stoichiometric Mn3Ga crystallizes in the D022 structure (abstract figure) and is a collinear ferrimagnet with an easy c‐axis. It exhibits a unique combination of low magnetization, high uniaxial anisotropy, high Curie temperature and high spin polarization, which suit the requirements for spin torque memories down to 10 nm in size. Mn2Ga, on the other hand, exhibits much higher magnetization, high perpendicular anisotropy and high Curie temperature but a lower spin polarization, which make it a potential candidate for high density bit‐patterned recording with areal densities up to 10 Tb inch−2 (∼15 kb µm−2) and 10‐year thermal stability. The flexibility of the D022 structure allows a variety of magnetic materials to be synthesized with varying x to suit specific magnetic applications. Hexagonal D019‐Mn3Ga films are antiferromagnetic, which could be useful for exchange bias. magnified image
(a) The tetragonal D022 unit cell of Mn3Ga. Ga atoms are ordered in a body‐centred tetragonal structure and Mn atoms occupy 2b (red) and 4d (green) sites. (b) The hexagonal D019 unit cell of Mn3Ga.
Sorption Phenomena in Packaged Foods: Factors Affecting Sorption Processes in Package–Product Systems
Authors: Caner C. 
Published: April 2011

SUMMARYSorption process can readily occur from many foods. The sorption behaviours result in loss of food quality and shelf life of the packaged foods by altering the aroma compound profile. Although the intensity of the aroma of a packaged foodstuff depends on the vapour pressure, the interaction of the volatile organic moieties with other food constituents and the aroma barrier characteristics of the package, the nature of the aroma is also imperative in determining the extent of sorption. Sorption properties are largely determined by packaging characteristics, flavour molecules properties, food matrix composition and environmental conditions. The chemical composition, chain stiffness, morphology, polarity and crystallinity of the polymer influence flavour absorption as much as the chemical composition, concentration and polarity of the flavour compounds, as well as the presence of other chemical constituents. External factors such as duration of storage, relative humidity, temperature and the presence of other food components can also affect the solubility of aroma compounds in packaged foods. Factors relating to both chemical and physical structure of flavour, food and packaging influence the degree of sorption and also the sorption pattern. Sorption from the packaged foods is of major concern in the selection and use of plastic packaging materials for food packaging. The present review highlights some of the major factors influencing the sorption process. The scientific principles related to sorption are reviewed and distinguished. Copyright © 2011 John Wiley & Sons, Ltd.
PCM study of the solvent and substituent effects on bond dissociation energies of the ONO Bond—A DFT study
Authors: Xiaohong Li , Xianzhou Zhang 
Published: April 2011

AbstractA PCM continuum model, at the B3LYP, B3P86, and B3PW91 three‐parameter hybrid DFT methods with 6‐311G** basis set, is used to study the bond dissociation energies (BDEs) of benzyl nitrites. Compared the computed results with the experimental values, it is noted that B3PW91 functional is the best method to compute the BDEs of benzyl nitrites. The solvent and substituent effects on the BDEs of the ONO bond are analyzed, and it is shown that the BDE of the ONO bond decreases with the increment of the Hammett constants of substituent groups on benzene for benzyl nitrites except C6H5CH2ONO. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012
REMOVAL OF AQUATIC WEEDS GREATLY ENHANCES FISH COMMUNITY RICHNESS AND DIVERSITY: AN EXAMPLE FROM THE BURDEKIN RIVER FLOODPLAIN, TROPICAL AUSTRALIA
Authors: Perna C. N. , Cappo M. , Pusey B. J. , Burrows D. W. , Pearson R. G. 
Published: April 2011

ABSTRACTHydrological changes associated with irrigation, in conjunction with increased nutrient concentrations and aquatic plant densities, have greatly impacted fish habitat values on the Burdekin River floodplain. The two most significant weeds in the Burdekin floodplain are water hyacinth (Eichhornia crassipes) and para grass (Urochloa mutica). Water hyacinth creates a base for the para grass (and then other weeds) to grow out into deeper water, creating weed mats that can then only be removed by mechanical means or floods of the largest magnitude. We attempted to rehabilitate floodplain lagoons by the mechanical removal of floating weed mats and monitored the result by measuring the subsequent effects on fish habitats and fish communities. Prior to weed removal, fish habitats were generally of poor quality, and fish community structure was skewed away from rich native assemblages to depauperate communities dominated in some instances by alien species. Poor water quality arising from floating weed mats is considered to be the main determinant of reduced fish abundance and diversity. After mechanical weed removal, recovery of water quality and physical habitat led to the re‐establishment of many native fish species. Key refuge habitats within the distribution channels were a critical source of recruits for fishes dispersing during times of elevated seasonal flows into the newly rehabilitated reaches. This study demonstrates that floating alien weed mats have significant negative effects upon aquatic communities and that mechanical removal of these weed mats (as opposed to chemical removal) results in dramatic improvements in native fish species richness and abundance. Copyright © 2011 John Wiley & Sons, Ltd.
VEGETATION–LANDFORM ASSEMBLAGES ALONG SELECTED RIVERS IN THE CZECH REPUBLIC, A DECADE AFTER A 500‐YEAR FLOOD EVENT
Authors: Loučková B. 
Published: April 2011

ABSTRACTRivers with a natural flow regime strongly influence the dynamics of riparian plant communities through hydrological and geomorphological processes. In this study, associations between fluvial landforms and vegetation are investigated on three near‐natural rivers in the Czech Republic a decade after a 500‐year return period flood in July 1997. This extreme disturbance destroyed the anthropogenically modified river channels and created suitable conditions for a range of ecosystems with high diversity and ecological stability. Field surveys were conducted on fluvial landforms (bars, islands, banks, floodplains and terraces) along three ‘renaturalized’ rivers, where no technical modifications had subsequently been made to their channels outside urban areas and the floodplains had been left in a post‐flood state. Vegetation species abundance and 13 environmental variables (topographical, hydrological and soil) were investigated in summer 2007, 10 years after the extreme flood disturbance. The results suggest that the recently created fluvial geomorphic forms are key environmental determinants of riparian vegetation distribution patterns. A range of statistical analyses illustrate that some plant species show predictable patterns of occurrence that correspond with the fluvial forms, supporting a fourfold grouping of herbaceous and woody species and the identification of typical plant communities associated with gravel bars, islands, banks, floodplains and terraces. An investigation of the species richness found on different fluvial landforms showed that the highest number of species occurred on the floodplain and decreased gradually towards the channel bed and towards terraces. Investigation of existing conditions in reaches of rivers with natural dynamics of fluvial processes provides valuable information that can be used as an effective tool for planning restoration strategies and precise management. However, the most important finding of this study is the remarkable establishment of complex river corridor vegetation–landform associations within 10 years of a 500‐year flood that removed the heavily cultivated landscape that had existed before the event. Copyright © 2011 John Wiley & Sons, Ltd.