bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and characterization of porous poly(vinyl ester) resin monoliths as separation media
Authors: Yang Jing , Yang Gengliang , Liu Haiyan , Bai Ligai , Zhang Qiaoxia
Published: July 2010

Porous poly(vinyl ester) resin monolithic supports were first prepared by radical polymerization of the continuous phase of oil in water high‐internal‐phase emulsions. Vinyl ester (VE) resin was used as the monomer, ethylene glycol dimethacrylate was used as a crosslinker, and poloxamer 127 was used as the emulsifier in the emulsion polymerization. The prepared columns were evaluated by scanning electron microscopy, mercury intrusion porosimetry, and Fourier transform infrared spectroscopy to observe the morphological characteristics and confirm the absorbance based on the VE resin polymer. The obtained monolith showed not only higher column permeability but also lower back pressure and higher column efficiency. To investigate the absorption performance of the monolithic column, a maximum loading capacity experiment was also applied with lysozyme (Lys), and the results show that the maximum adsorption of the poly(vinyl ester) resin monolith was 1.579 mg/g. Moreover, the capabilities of separation on this column in conjunction with high‐performance liquid chromatography were investigated. Immunoglobulin could be separated from human plasma and chicken egg yolk with high resolution within 4 min. Additionally, fast separation of two mode proteins (interleukin‐18 and Lys) was achieved on the monolith within 2 min at the rate of 1445 cm/h, which demonstrated the potential of the poly(vinyl ester) resin monolith for the fast separation of proteins. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Coupled‐single‐particle and Monte Carlo model for propylene polymerization
Authors: Wang Wei , Zheng Zu‐Wei , Luo Zheng‐Hong
Published: July 2010

A coupled‐single‐particle and Monte Carlo model was used to simulate propylene polymerization. To describe the effects of intraparticle transfer resistance on the polymerization kinetics, the polymeric multilayer model (PMLM) was applied. The reaction in each layer of the PMLM was described with the Monte Carlo method. The PMLM was solved together with the Monte Carlo model. Therefore, the model included the factors of the mass‐ and heat‐transfer resistance as well as the stochastic collision nature of the polymerization catalyzed with single‐site‐type/multiple‐site‐type catalysts. The model presented results such as the polymerization dynamics, the physical diffusion effect, and the polymer molecular weight and its distribution. The simulation data were compared with the experimental/actual data and the simulation results from the uniform Monte Carlo model. The results showed that the model was more accurate and offered deeper insight into propylene polymerization within such a microscopic reaction–diffusion system. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Adsorption capacity, kinetics, and mechanism of copper(II) uptake on gelatin‐based hydrogels
Authors: Kumari Manju , Chauhan Ghanshyam S.
Published: July 2010

Gelatin‐based hydrogels were synthesized and characterized for use as Cu2+‐ion sorbents. Gelatin was crosslinked in the presence of two different monomers, that is, acrylamide (AAm) and/or 2‐hydroxypropyl methacrylate, with N,N‐methylenebisacrylamide, ammonium persulfate, and sodium bicarbonate. The as‐prepared hydrogels were further characterized by scanning electron microscopy, Fourier transform spectroscopy, and the study of their swelling behavior as a function of temperature, time, and pH to evaluate their structure–property relationships. The hydrogels were observed to be good sorbents of Cu2+, and a maximum uptake of 84.8% was observed within 2 h at 37°C and with 10 ppm of the Cu2+‐ion solution for the gelatin and polyacrylamide hydrogel, which also exhibited the maximum retention capacity at 14.9 mg/g after four feeds. All of the experimental data exhibited good matches with the Langmuir isotherm and followed pseudo‐second‐order kinetics. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Effect of cocatalysts on ethylene polymerization with fluorinated bisphenoxyimine titanium as a catalyst
Authors: Li Ting , Kong Fan Wang , Liu Ran , Li Zhi Yun , Zhu Fang Ming
Published: July 2010

In this study, we examined various alkylaluminums, including triethylaluminum (TEA), triisobutylaluminum (TIBA), and diethylaluminum chloride (DEAC), as cocatalysts for the activation of ethylene polymerizations in the presence of a fluorinated Fujita group invented titanium (FI‐Ti) catalyst, bis[N‐(3‐tert‐butylsalicylidene)‐2,3,4,5,6‐pentafluoroanilinato] titanium(IV) dichloride (complex 1). DEAC, because of the strong Lewis acidity, was an efficient cocatalyst for activating complex 1 for the ethylene polymerizations, whereas TEA and TIBA as cocatalysts could hardly polymerize ethylene. The effects of the polymerization temperature and Al/Ti molar ratio on the formation of active species, properties, and molecular weight of the resulting polyethylene were investigated. In the complex 1/DEAC catalyst system, the oxidation states of Ti active species were determined by electron paramagnetic resonance. The results demonstrated that Ti(IV) active species were inclined to polymerize ethylene and yielded high‐molecular‐weight polyethylene. Comparatively, Ti(III) active species resulted from the reduction of Ti(IV) by DEAC and afforded oligomers. Moreover, the bigger steric bulk for the cocatalysts was necessary to achieve ethylene living polymerization with the fluorinated FI‐Ti catalyst. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Morphological study of two‐phase polymer blends during compounding in a novel compounder on the basis of elongational flows
Authors: Bouquey Michel , Loux Cyril , Muller René , Bouchet Gilles
Published: July 2010

A new laboratory‐scale mixing device based on an original concept was built and tested. This device has important technical features such as tightness to liquids and gases, the possibility of direct specimen molding after mixing, and easy handling of reactive systems. In comparison with existing laboratory mixers, the flow in this mixer is characterized by a high contribution from elongational flow. Morphological data on model polystyrene/poly(methyl methacrylate) blend systems have proved the high distributive and dispersive mixing efficiency in comparison with a classical rotational batch mixer. The influence of different experimental parameters such as the flow rate, mixing time, mixing element geometry, and viscosity ratio of blends is characterized and discussed. Much finer dispersions have been obtained with this new device versus those obtained with a conventional mixer with equivalent specific energy input. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis of oxadiazole‐based polymers containing a carbazole–vinylene or fluorene–vinylene group and their hole‐injection/transport behavior in light‐emitting diodes
Authors: Wang Hui , Ryu Jeong‐Tak , Kwon Younghwan
Published: July 2010

A series of conjugated (poly{N‐(2‐ethylhexyl)‐3,6‐carbazole–vinylene‐alt‐[(2,5‐bisphenyl)‐1,3,4‐oxadiazole]}) and nonconjugated (poly{N‐(2‐ethylhexyl)‐3,6‐carbazole–vinylene‐alt‐[(2,5‐bisphenol)‐1,3,4‐oxadiazole]}) and poly{9,9‐dihexyl‐2,7‐fluorene–vinylene‐alt‐[(2,5‐bisphenol)‐1,3,4‐oxadiazole]}) polymers containing oxadiazole and carbazole or fluorene moieties in the polymer backbone were synthesized with a multiple‐step procedure. The properties of the polymers, including the photophysical and electrochemical characteristics, could be fine‐tuned by adjustment of the components or structures in the polymer chains. The polymers were used to examine the hole‐injection/transport behavior as hole‐injection/hole‐transport layers in double‐layer indium tin oxide (ITO)/polymer/aluminum tris(8‐hydroxyquinoline)/LiF/Al devices by the determination of their energy levels. The effects of the polymers in these devices on the charge‐transport behavior were compared with a control device fabricated with poly(ethylenedioxythiophene) (PEDOT)–poly(styrene sulfonate) (PSS). Devices containing the synthesized polymers showed comparable adhesion to the ITO anode and good hole‐injection/transport performance. In addition, they exhibited higher electroluminescence over an identical range of current densities than the control device. This was attributed to the prevention of radiative exciton quenching caused by the PEDOT–PSS interfaces and the improvement of electron/exciton blocking due to the higher electron affinity of the synthesized polymers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Nitrile rubber/organomontmorillonite nanocomposites produced by solution and melt compounding: Effect of the polarity of the quaternary ammonium intercalants
Authors: Soares Bluma G. , de Oliveira Marlucy , Zaioncz Soraia , Gomes Ana C. O. , Silva Adriana A. , Santos Kelly S. , Mauler Raquel S.
Published: July 2010

A comparative study of the development of nitrile rubber (NBR) based nanocomposites was performed; two organomontmorillonites (Cloisite 15A and Cloisite 30B) and two procedures for clay dispersion (melt blending and solution intercalation) were used. The nanocomposites were cured with a system based on dicumyl peroxide in the presence of m‐phenylenebismaleimide as a coagent for curing. The dispersion of the organoclay inside the NBR matrix was investigated with transmission electron microscopy and X‐ray diffraction. All the cured systems displayed a combination of intercalated, partially exfoliated clay platelets and confined, deintercalated clay; the degree of dispersion depended on the amount of clay, the type of intercalant, and the intercalation procedure. The highest amount of intercalated/exfoliated clay was obtained with a previous dispersion of the clay (Cloisite 30B) in an NBR solution. All the nanocomposites presented outstanding tensile strength and creep response, and this indicated a reinforcing effect of the layered silicates. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Preparation of microwave‐assisted polymer‐grafted softwood kraft pulp fibers. Enhanced water absorbency
Authors: Goetz Lee A. , Sladky Jessica R. , Ragauskas Arthur J.
Published: July 2010

A wood pulp cellulose‐based hydrogel material was prepared with poly(methyl vinyl ether‐co‐maleic acid) (PMVEMA), polyethylene glycol (PEG), and softwood ECF kraft pulp via microwave and thermal esterification and compared via hydrogel absorption and retention of water and 0.10M NaCl. The microwave initiated reaction time was optimized to 105 s at 1600 W based on maximum water absorption of 96 g/g of the 49% PMVEMA pulp hydrogels. The influence of reaction variables such as pulp fiber size and the weight ratios of PMVEMA to pulp were investigated. The maximum water absorbency of the milled pulp fibers microwave initiated products was 151 g/g, whereas the maximum water absorbency of the milled pulp fibers thermally initiated hydrogels was 198 g/g. In addition, the microwave initiated hydrogels retained a maximum of 67% of absorbed water after centrifugation at 770 rpm for 10 min, whereas the thermally initiated hydrogels retained a maximum of 49% of water absorbed. Fourier transform infrared spectroscopy (FTIR) was used to confirm the esterification of the PMVEMA with the pulp cellulose. Microwave initiated crosslinking successfully produced a pulp hydrogel with a shorter reaction time and comparable or improved water absorption and retention properties when compared with the traditional thermally crosslinked pulp hydrogel system. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Study of third‐order optical nonlinearities of substituted hydrazones in PMMA
Authors: Vijayakumar S. , Adhikari Adithya , Kalluraya Balakrishna , Sharafudeen K. N. , Chandrasekharan K.
Published: July 2010

We investigated the third‐order nonlinear optical properties of donor–acceptor substituted hydrazones doped into PMMA matrix using single beam Z‐scan technique at 532 nm. The magnitude of third‐order susceptibility, χ(3) is of the order of 10−13esu. The nonlinear refractive index, n2 and the molecular second order hyperpolarisability, γh are of the order of 10−11esu and 10−32esu, respectively. The compounds exhibit larger third‐order NLO properties in PMMA host when compared to the pure compounds. The study reveals that these hydrazones are a good candidate of nonlinear optical materials for photonic applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis and characterization of poly(ether amide ether ketone)/poly(ether ketone ketone) copolymers
Authors: Huang Bin , Zhu Meihua , Cai Mingzhong
Published: July 2010

A new monomer, N,N′‐bis(4‐phenoxybenzoyl)‐m‐phenylenediamine (BPPD), was prepared by condensation of m‐phenylenediamine with 4‐phenoxybenzoyl chloride in N,N‐dimethylacetamide (DMAc). A series of novel poly(ether amide ether ketone) (PEAEK)/poly(ether ketone ketone) (PEKK) copolymers were synthesized by the electrophilic Friedel‐Crafts solution copolycondensation of terephthaloyl chloride (TPC) with a mixture of diphenyl ether (DPE) and BPPD, over a wide range of DPE/BPPD molar ratios, in the presence of anhydrous AlCl3 and N‐methylpyrrolidone (NMP) in 1,2‐dichloroethane (DCE). The influence of reaction conditions on the preparation of copolymers was examined. The copolymers obtained were characterized by different physicochemical techniques. The copolymers with 10–25 mol % BPPD were semicrystalline and had remarkably increased Tgs over commercially available PEEK and PEKK due to the incorporation of amide linkages in the main chains. The copolymers III and IV with 20–25 mol % BPPD had not only high Tgs of 184–188°C, but also moderate Tms of 323–344°C, having good potential for the melt processing. The copolymers III and IV had tensile strengths of 103.7–105.3 MPa, Young's moduli of 3.04–3.11 GPa, and elongations at break of 8–9% and exhibited outstanding thermal stability and good resistance to organic solvents. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
X‐ray scattering experiments on sputtered titanium dioxide coatings onto PVDF polymers for self‐cleaning applications
Authors: Marques S. M. , Tavares C. J. , Lanceros‐Méndez S. , Denchev Z.
Published: July 2010

The performance of active polymer substrates used in sensor and actuator or tactile display applications can be hindered by the inevitable soiling of their surface. A possible approach to overcome this problem is to deposit a self‐cleaning coating onto the polymer surface, taking care that the layer underneath withholds its intrinsic properties. In this work, titanium dioxide, TiO2, was naturally chosen for coating material due to its inherent photocatalytic properties. Thus, TiO2 thin films were deposited by reactive magnetron sputtering on poly(vinilydene fluoride) ‐ (PVDF) substrates, in its α‐ (nonelectroactive) and β‐ (electroactive) phases. Wide angle x‐ray scattering (WAXS) experiments in a synchrotron were performed to monitor the crystalline structure of the polymer substrates upon thin film deposition and also to assess the crystalline structure of the TiO2 coating at different temperatures. In the WAXS patterns of the coated α‐PVDF, the TiO2 polymorph anatase phase can be distinguished. At the same time, no explicit diffraction peaks for anatase were detected in the coated β‐PVDF. Fourier transform infrared spectroscopy evidenced that the chemical structure of PVDF is unaffected by the coating deposition process. These structural results have been correlated with the photocatalytic properties of the TiO2 coatings. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Water assisted exfoliation of PA6/clay nanocomposites using a twin screw extruder: Effect of water contact time
Authors: Molajavadi Vadoud , Garmabi Hamid
Published: July 2010

Polyamide 6/Na+ montmorillonite (Na+ MMT) nanocomposites (NCs) were produced in a corotating twin screw extruder. Water was injected into the extruder as an intercalating/exfoliating agent. The wide angle X‐ray diffraction and linear dynamic measurements were used to investigate the structure of the prepared samples. The results showed that the contact time between water and melt PA6/Na+MMT in the extruder is an important factor to achieve a high level of exfoliation. The ratio of water‐injection rate to clay feeding rate did not reveal a major effect on the exfoliation of pristine MMT. The results also demonstrated that the order of injection of water during the mixing process did not have a distinguishable effect on the level of exfoliation. This processing method was found to be controlled by a diffusion mechanism caused by the presence of water molecules during the process. Improvement of tensile properties is in a great agreement with the rheological and morphological findings. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Crosslinking of electrospun fibrous gelatin scaffolds for apatite mineralization
Authors: Zhao Jin , Zhao Yuping , Guan Qianqian , Tang Gongwen , Zhao Yunhui , Yuan Xiaoyan , Yao Kangde
Published: July 2010

Fibrous gelatin scaffolds fabricated via electrospinning followed by crosslinking were used as substrates for apatite mineralization. Gelatin macromolecules were confined by their fibers and further restricted by the crosslinked structure while proper flexibility could be attained upon hydration. After 4 or 5 days of mineralization, partially carbonated hydroxyapatite was proved to deposit uniformly on the surface of the fibers. The property of the substrate, such as stiffness of the scaffolds and flexibility of macromolecules chain, was changed by different crosslinking ways. The influences of these properties on the formation of apatite were also investigated. Results showed that a relatively less rigid interface and more flexible chain acquired by glutaraldehyde solution crosslinking seemed to favor the nucleation of minerals and to reduce the size of the inorganic products. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Effect of ambient atmosphere on crosslinking of polysilazanes
Authors: Chavez Ricardo , Ionescu Emanuel , Balan Corneliu , Fasel Claudia , Riedel Ralf
Published: July 2010

The influence of ambient atmosphere on the crosslinking process of two commercially available polysilazanes with different molecular units in the backbone structure (one polysilazane with and one without urea units) was studied at different temperatures using oscillatory rheometry under isothermal conditions. The measurements were performed using cone/plate, plate/plate, and Couette geometries to assess the influence of the contact surface of the samples with air on their crosslinking behavior. The crosslinking process of the investigated polysilazanes in ambient atmosphere was found to occur faster than that in inert atmosphere. DSC and FTIR‐spectroscopic investigations indicate that hydrolysis and polycondensation processes occur in both polysilazanes when crosslinked in air. Interestingly, the effect of moisture was found to be more pronounced in the case of the urea derivative. The evolution of the measured complex viscosity and dynamic moduli supported this finding. Furthermore, the variation of the time derivative of complex viscosity (dη*/dt) emphasizes structural changes during crosslinking of the samples which were ascribed to their contact with the ambient atmosphere. This study emphasizes the high potential of rheometry in investigating the crosslinking behavior of polymers in inert and ambient atmosphere. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis of polyaniline nanoparticle grafted silica gel and study of its Cr(VI) binding property
Authors: Chowdhury P. , Mondal P. , Roy K.
Published: July 2010

Polyaniline nanoparticles have been synthesized through simple micelle technique and then grafted it with silanized silica gel to develop a novel hybrid material. The nanoparticles are characterized by UV‐Vis, TEM, CV, SEM, TGA, DTG, and DSC. Silanization and grafting reactions are evaluated by FTIR and chemical test. The Cr(VI) binding behavior of the composite is studied in various pH of the medium, and both competitive and noncompetitive conditions. The particle size, adsorption capacity, and surface area of the material are found to be 100 nm, 135 mg/g, and 720 m2/g, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Expression of pheromone biosynthesis activating neuropeptide and its receptor (PBANR) mRNA in adult female Spodoptera exigua (Lepidoptera: Noctuidae)
Authors: Cheng Yunxia , Luo Lizhi , Jiang Xingfu , Zhang Lei , Niu Changying
Published: July 2010

The full‐length cDNA of pheromone biosynthesis activating neuropeptide receptor (PBANR) was cloned from the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae); it included an open reading frame of 1,053 bp encoding 350 amino acids. The PBANR of S. exigua (SePBANR) was structurally characteristic of G protein–coupled receptor and its amino acid sequence shared 98% identity with the PBANR of Spodoptera littoralis. Both pheromone biosynthesis activating neuropeptide (PBAN) and PBANR mRNA abundance were measured in the brain‐subesophageal ganglion complex, pheromone gland, ventral nerve cord, and ovary of S. exigua female moths by real‐time RT‐PCR. The abundance of PBAN mRNA in brain‐subesophageal ganglion complex and PBANR mRNA in pheromone gland was significantly greater compared to other tissues, suggesting that the ligand‐receptor relationship of PBAN and PBANR exists quantitatively in S. exigua. Both PBAN and PBANR expression displayed a remarkable diurnal rhythm, for they were low and stable during the photophase (07:00–21:00) and increased markedly during the scotophase (with a maximum abundance at 23:30) in 3‐day‐old female moths. The abundance of PBAN and PBANR increased steadily from the 1st day to the 5th day of the adult female life. The pattern of both diurnal and daily expression of PBAN and PBANR mRNA were coincident with enhanced capacity of sex pheromone release and mating of S. exigua moths during the same period. We infer from these results that pheromone biosynthesis and release in S. exigua is regulated by PBAN via up‐regulating synthesis. © 2010 Wiley Periodicals, Inc.
Vitamin C content in plants is modified by insects and influences susceptibility to herbivory
Authors: Goggin Fiona L. , Avila Carlos A. , Lorence Argelia
Published: July 2010

Analysis of a diverse cross‐sample of plant‐insect interactions suggests that the abundance of vitamin C (L‐ascorbic acid, ascorbate or AsA) in plants influences their susceptibility to insect feeding. These effects may be mediated by AsAs roles as an essential dietary nutrient, as an antioxidant in the insect midgut, or as a substrate for plant‐derived ascorbate oxidase, which can lead to generation of toxic reactive oxygen species. Ascorbate can also influence the efficacy of plant defenses such as myrosinases and tannins, and alter insects' susceptibility to natural enemies. Conversely, herbivores appear to influence both de novo synthesis and redox cycling of AsA in their host plants, thereby potentially altering the nutritional value of crops and their susceptibility to pests. The recent development of genetically modified crops with enhanced AsA content provides both an impetus and a tool set for further studies on the role of AsA in plant‐insect interactions.
General solutions to consistency problems in multiple hypothesis testing
Authors: Zhao Haibing , Wang Bushi , Cui Xinping
Published: July 2010

Coherence and consonance are the two important concepts to ensure consistent conclusions drawn from multiple tests. Unlike coherence, consonance of a multiple testing procedure (MTP) has not yet received much attention. Although most of the MTPs used in practice are consonant, cases still exist that dissonant tests have to be used due to their unique advantages, for example, the likelihood ratio tests and sum tests. Consonance adjustments are necessary for such tests to avoid difficulty in interpretation. Moreover, in terms of detecting elementary hypotheses, a consonant test procedure is uniformly more powerful than the corresponding dissonant one. In this paper, several general methods using the partitioning principle to construct (strongly) consonant and strongly coherent MTPs are proposed. As a result, any dissonant (but coherent) multiple level α test can be improved by a consonant one without any cost in terms of inferences on elementary hypotheses.
Photomobile luminescent polymeric materials on the basis of boron and europium chelates
Authors: Karpenko A. A. , Fedorenko E. V. , Mirochnik A. G.
Published: July 2010

The photomechanical effect was found in a polymer composition on the basis of polymethylmethacrylate with embedded molecules of the luminophor incapable to undergo photochemical isomerization (anthracenoylacetonate of boron difluoride and dibenzoylmethanatoeuropiate triethylammonium), unlike other compounds having the above effect. The possibility of the development of a simple upward–downward movement drive on the basis of the above compounds was demonstrated. Copyright © 2010 John Wiley & Sons, Ltd.
Enzymatic activity and thermal stability of metallo proteins in hydrated ionic liquids
Authors: Fujita Kyoko , Ohno Hiroyuki
Published: July 2010

Hydrated choline dihydrogen phosphate (Hy[ch][dhp]) containing 30 wt% water was investigated as a novel protein solvent. The Hy[ch][dhp] dissolved some metallo proteins (cytochrome c, peroxidase, ascorbate oxidase, azurin, pseudoazurin and fructose dehydrogenase) without any modification. These proteins retained the surroundings of the active site after dissolution in Hy[ch][dhp]. Some metallo proteins were found to retain their activity in the Hy[ch][dhp]. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 1093–1099, 2010.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Mercury(II) promotes the in vitro aggregation of tau fragment corresponding to the second repeat of microtubule‐binding domain: Coordination and conformational transition
Authors: Yang Dan‐Jing , Shi Shuo , Zheng Leng‐Feng , Yao Tian‐Ming , Ji Liang‐Nian
Published: July 2010

The loss of metal homeostasis and the toxic effect of metal ion are important events in neurodegenerative and age‐related diseases, such as Alzheimer's disease (AD). For the first time, we investigated the impacts of mercury(II) ions on the folding and aggregation of Alzheimer's tau fragment R2 (residues 275‐305: VQIIN KKLDL SNVQS KCGSK DNIKH VPGGGS), corresponding to the second repeat unit of the microtubule‐binding domain, which was believed to be pivotal to the biochemical properties of full tau protein. By ThS fluorescence assay and electron microscopy, we found that mercury(II) dramatically promoted heparin‐induced aggregation of R2 at an optimum molar ratio of 1: 2 (metal: protein), and the resulting R2 filaments became smaller. Isothermal titration calorimetry (ITC) experiment revealed that the strong coordination of mercury(II) with R2 was an enthalpy‐controlled, entropy‐decreased thermodynamic process. The exceptionally large magnitude of heat release (ΔH1 = −34.8 Kcal mol−1) suggested that the most possible coordinating site on the R2 peptide chain was the thiol group of cysteine residue (Cys291), and this was further confirmed by a control experiment using Cys291 mutated R2. Circular dichroism spectrum demonstrated that this peptide underwent a significant conformational change from random coil to β‐turn structure upon its binding to mercury(II) ion. This study was undertaken to better understand the mechanism of tau aggregation, and evaluate the possible role of mercury(II) in the pathogenesis of AD. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 1100–1107, 2010.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
A liquid chromatography–tandem mass spectrometry method for the simultaneous quantification of escin Ia and escin Ib in human plasma: application to a pharmacokinetic study after intravenous administration
Authors: Liu Lidong , Wu Xiujun , Wu Dan , Wang Yingwu , Li Pengfei , Sun Yantong , Yang Yan , Gu Jingkai , Cui Yimin
Published: July 2010

A rapid and sensitive liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method was developed and validated for simultaneous quantification of escin Ia and escin Ib in human plasma. After a solid‐phase extraction (SPE), the analytes were separated on a Zorbax Extend C18 column by isocratic elution with a mobile phase of methanol–acetonitrile–10 mm ammonium acetate (27:27:46, v/v/v) at a flow rate of 1.0 mL/min and analyzed by mass spectrometry in the positive ion multiple reaction monitoring mode. The precursor to product ion transitions of m/z 1131.8 → 807.6 was used to quantify escin Ia and escin Ib. Good linearity was achieved over a wide range of 2.00–900 ng/mL for escin Ia and 1.50–662 ng/mL for escin Ib. The intra‐ and inter‐day precisions (as relative standard deviation) were less than 11% for each QC level of escin Ia and escin Ib. The accuracies (as relative error) were within ±5.27% for escin Ia and within ±4.07% for escin Ib. The method was successfully employed in a pharmacokinetic study after a single intravenous infusion administration of sodium aescinate injection containing 10 mg escin to each of the 10 healthy volunteers. Copyright © 2010 John Wiley & Sons, Ltd.
The study of the lipophilicity of some aminoalkanol derivatives with anticonvulsant activity
Authors: Waszkielewicz Anna , Szkaradek Natalia , Pękala Elżbieta , Galzarano Fabiola , Marona Henryk
Published: July 2010

A series of new (phenoxyethyl)aminoalkanol derivatives were synthesized and evaluated for their anticonvulsant activity. The most promising compound seemed to be (R,S)‐1N‐[(2,6‐dimethyl)phenoxyethyl]amino‐2‐butanol, which displayed anti‐MES activity (in mice, i.p.) with protective index (TD50/ED50) of 5.712, corresponding to that of phenytoin (6.6), carbamazepine (4.9) and valproate (1.7). The lipophilicity of compounds 1–17 exhibiting anticonvulsant activity was investigated. Their lipophilicities (RM0) were determined using reversed‐phase thin‐layer chromatography (RP‐TLC) with a mixture of acetone and water as mobile phases. The partition coefficients of 1–17 (logP) were also calculated using two computer programs (Pallas and ALOGPS) and compared with RM0. The relationship between anticonvulsant activity and lipophilicity of the tested substances was estimated. Copyright © 2010 John Wiley & Sons, Ltd.
Preparation of Bismuth Oxide Quantum Dots and their Photocatalytic Activity in a Homogeneous System
Authors: Zhang Hua , Wu Ping , Li Yan , Liao Lifang , Fang Zheng , Zhong Xinhua
Published: July 2010

Colloidal oil‐soluble Bi2O3 quantum dots (QDs) are synthesized through an alcoholysis route in organic media. Water‐soluble Bi2O3 QDs are then obtained from the initial oil‐soluble QDs through phase transfer by surface modification with mercaptopropionic acid. X‐ray diffraction and transmission electron microscopy studies show that the crystallinity is enhanced and particles grow larger after phase transfer. The water‐soluble Bi2O3 QDs exhibit excellent photocatalytic activity for the degradation of methyl orange at a wide range of pH values. After several cycles, the Bi2O3 QDs retain high degradation efficiency. Simulation according to the first‐order reaction dynamics indicates that the degradation reaction may follow complicated quasi‐homogeneous photocatalysis.
Does combination of lipid formulation of amphotericin B and echinocandins improve outcome of invasive aspergillosis in hematological malignancy patients?
Authors: Mihu Coralia N. , Kassis Christelle , Ramos Elizabeth R. , Jiang Ying , Hachem Ray Y. , Raad Issam I.
Published: July 2010

BACKGROUND:

In vitro and in vivo studies suggested that combination of lipid formulation of amphotericin B (L‐AMB) and echinocandins may have a synergistic or additive effect against Aspergillus. Furthermore, clinical studies suggested that this combination may improve response of invasive aspergillosis (IA).

METHODS:

Between August 1993 and June 2008, the authors identified a total of 159 patients with hematological malignancies who received salvage therapy for IA, with L‐AMB alone, echinocandins alone, or a combination of L‐AMB and echinocandins. Clinical characteristics, response to salvage therapy, and death up to 12 weeks after initiation of salvage therapy were retrospectively determined for all patients.

RESULTS:

Seventy patients received salvage therapy with L‐AMB, 18 patients received echinocandins alone (89% of whom received caspofungin), and 71 patients received the combination therapy of amphotericin B and echinocandins (90% of who received caspofungin). The 3 salvage treatment groups were comparable in regard to clinical characteristics; graft versus host disease was more frequently encountered in the echinocandin group, whereas more patients in the L‐AMB and combination groups had neutropenia and received immunotherapy. The response to salvage therapy was better in the echinocandin group (9% L‐AMB, 28% echinocandins, and 21% for combination therapy). The 3 groups had a comparable rate of Aspergillus‐related death (58%‐64%) and overall mortality (61%‐67%).

CONCLUSIONS:

The combination of L‐AMB and echinocandins offered no advantage in terms of improving response or reducing mortality over either drug alone. Hence, this combination will only add to the cost of therapy without any improvement in outcome in patients with hematological malignancies. Cancer 2010. © 2010 American Cancer Society.
Investigation of carrier scattering mechanisms in molybdenum diselenide single crystals by hall effect measurements
Authors: Sumesh C. K. , Patel K. D. , Pathak V. M. , Srivastav R.
Published: July 2010

Molybdenum diselenide (MoSe2) belong to the large family of layered transition metal dichalcogenides. It consists of weakly coupled sandwiched layers i.e. Se – Mo – Se in which a Mo atom layer is enclosed within two Se layers. This structure makes MoSe2 extremely anisotropic in character and leads to unusual structural properties. In addition, MoSe2 possess flexible nature along with good carrier mobility to make them potential candidate for fabricating flexible high mobility electronic devices such as Schottky barrier devices, FETs, solar cell etc. In context of this authors made an effort to study the low temperature (12 < T < 300 K) electronic transport properties of Molybdenum diselenide (MoSe2). Through the investigation the temperature dependent Hall mobility study revealed that the grown crystals of MoSe2possess a mixed scattering mechanism. It has been found that observed temperature dependant mobility has at least two transitions from lattice to impurity scatterings showing an imprint of multicarrier nature of this semiconductor originating from its complex band structure. It has been observed that the studied crystals have at least two group of carriers of differing origins in which transition between dominant scattering mechanisms occur at different temperatures. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling and Measurement of Toroidal Currents in the HSX Stellarator
Authors: Schmitt J. C. , Talmadge J. N. , Lore J.
Published: July 2010

A set of magnetic diagnostics, including Rogowski coils, diamagnetic loops and two poloidal ‘belts’ of 3‐axis pick‐up coils measure the magnetic field at several locations around HSX. The two belts are separated by ≈1/3 of a field period and measure the local magnetic field vector at 16 poloidal locations at the two toroidal angles. With the VMEC [1] and PENTA [2] codes, a calculation of the Pfirsch‐Schlüter (PS) and bootstrap currents is performed. The 3‐D equilibrium reconstruction code V3FIT [3] is then used to calculate the expected response of the magnetic diagnostics. The sensitivity of the diagnostic set to features in both the PS and bootstrap current is explored. Because of the lack of toroidal curvature, the dipole PS current has a helical rotation and nearly reverses at the two toroidal locations. The bootstrap current in HSX is in the opposite direction compared to that in a tokamak. Compared to a tokamak, the relative magnitude of each current is reduced by a factor of the effective transform (≈3) [4]. The PS current reaches steady state quickly, whereas the bootstrap current rises throughout the discharge on a 50‐500 ms timescale. In most cases, the toroidal current is still rising at the end of the discharge, reaching 0.4‐0.6 kA. A 3‐D model that relies on the calculation of the susceptance matrix [5] is used to calculate the time evolution of the toroidal current (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the Resonant Magnetic Perturbation on the Plasma Boundary in DIII‐D
Authors: Jakubowski M.W. , Evans T.E. , Fenstermacher M.E. , Lasnier C.J. , Schmitz O. , Wolf R.C. , Baylor L.R. , Boedo J.A. , Burrell K.H. , Frerichs H. , Grassie J.S. de , Gohil P. , Mordijck S. , Moyer R. A. , Leonard A. W. , Reiter D. , Samm U. , Schaffer M. J. , Osborne T. H. , Unterberg E. A. , Watkins J. G.
Published: July 2010

Stochastic boundaries in fusion devices have been investigated in tokamaks, stellarators and reversed field pinch experiments for many years. However, since edge localized modes (ELMs) have been successfully eliminated in H‐mode plasmas at the DIII‐D tokamak [1,2] with small, edge resonant magnetic perturbations, they have become a widely investigated topic in tokamaks. In DIII‐D stochastic boundaries are produced by coils external to the plasma. The magnetic field there consists of field lines with very different connection lengths, which produces a three dimensional, heterogenous structure of stochastic volume. The most obvious manifestation of the perturbed plasma edge is the strike line splitting observable in heat and particle fluxes, which changes with collisionality. The interaction of the magnetic perturbation and the magnetic equilibrium is of a resonant nature and the structure of the stochastic volume is a strong function of q95. This is observed as a modulation of e.g. electron temperature as measured by ECE or Thomson scattering. In this work we summarize recent experimental findings on properties of the stochastic boundary in DIII‐D (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Loss of Necdin impairs myosin activation and delays cell polarization
Authors: Bush Jason R. , Wevrick Rachel
Published: July 2010

NDN is one of several genes inactivated in Prader–Willi syndrome (PWS), a developmental disorder characterized by obesity, hypotonia, and developmental delay. We demonstrate that loss of Necdin in murine and human fibroblasts impairs polarity initiation through a Cdc42‐myosin‐dependent pathway, thereby reducing cell migration. We identified defective polarization in both primary neuron cultures and in the developing limb in Ndn‐null mice. Ndn‐null neurons fail to activate myosin light chain and display defective polarization with respect to a brain‐derived neurotrophic factor gradient. Pax3+ muscle progenitors in Ndn‐null developing forelimbs display defective polarization, do not adequately migrate into the dorsal limb bud, and extensor muscles are consequently smaller. These results provide strong evidence that Necdin is a key protein regulating polarization of the cytoskeleton during development. Furthermore, this is the first demonstration of a cellular defect in PWS and suggests a novel molecular mechanism to explain neurological and muscular pathophysiologies in PWS. genesis 48:540–553, 2010. © 2010 Wiley‐Liss, Inc.
Polyoxometalate‐Based Metal‐Organic Frameworks as Heterogeneous Catalysts for Selective Oxidation of Ethylbenzene
Authors: Yu Fan , Zheng Pei‐Qing , Long Yu‐Xiang , Ren Yan‐Ping , Kong Xiang‐Jian , Long La‐Sheng , Yuan You‐Zhu , Huang Rong‐Bin , Zheng Lan‐Sun
Published: July 2010

The catalytic properties of four polyoxometalate (POM)‐based metal‐organic frameworks, {[Cu2(4,4′‐bipy)4(H2O)4](SiW12O40)(H2O)18}n (1), {[Cu2(4,4′‐bipy)4(H2O)4](SiW12O40)(4,4′‐bipy)2(H2O)4}n (2), {[Cu2(4,4′‐bipy)4(H2O)4](PW12O40)(H2O)18}n (3), and {[Cu2(4,4′‐bipy)4(H2O)4](PMo12O40)(H2O)18}n (4) (bipy = bipyridine), for the oxidation of ethylbenzene were investigated. Complexes 1–4, which feature 3D frameworks formed through static incorporation between distinct Keggin POMs and the same voids in the 2D network of [Cu2(4,4′‐bipy)4(H2O)4]n4n+, show the distinct conversion and selectivity for the oxidation of ethylbenzene. Investigation into the difference in the catalytic activity of 1–4 reveals that the oxidation of the substrate was performed in the pore of the framework and that the valence of the metal ion in the polyoxometalates significantly affects the catalytic activity of the 3D framework.
Invariance of firing rate and field potential dynamics to stimulus modulation rate in human auditory cortex
Authors: Mukamel Roy , Nir Yuval , Harel Michal , Arieli Amos , Malach Rafael , Fried Itzhak
Published: July 2010

The effect of stimulus modulation rate on the underlying neural activity in human auditory cortex is not clear. Human studies (using both invasive and noninvasive techniques) have demonstrated that at the population level, auditory cortex follows stimulus envelope. Here we examined the effect of stimulus modulation rate by using a rare opportunity to record both spiking activity and local field potentials (LFP) in auditory cortex of patients during repeated presentations of an audio‐visual movie clip presented at normal, double, and quadruple speeds. Mean firing rate during evoked activity remained the same across speeds and the temporal response profile of firing rate modulations at increased stimulus speeds was a linearly scaled version of the response during slower speeds. Additionally, stimulus induced power modulation of local field potentials in the high gamma band (64–128 Hz) exhibited similar temporal scaling as the neuronal firing rate modulations. Our data confirm and extend previous studies in humans and anesthetized animals, supporting a model in which both firing rate, and high‐gamma LFP power modulations in auditory cortex follow the temporal envelope of the stimulus across different modulation rates. Hum Brain Mapp, 2011. © 2010 Wiley‐Liss, Inc.
Sequential temporo‐fronto‐temporal activation during monitoring of the auditory environment for temporal patterns
Authors: Halgren Eric , Sherfey Jason , Irimia Andrei , Dale Anders M. , Marinkovic Ksenija
Published: July 2010

Subjects detected rarely occurring shifts between two simple tone‐patterns, in a paradigm that dissociated the effects of rarity from those of pitch, habituation, and attention. Whole‐head magnetoencephalography suggested that rare attended pattern‐shifts evoked activity first in the superior temporal plane (sTp, peak ∼100 ms), then superior temporal sulcus (sTs, peak ∼130 ms), then posteroventral prefrontal (pvpF, peak ∼230 ms), and anterior temporal cortices (aT, peak ∼370 ms). Activity was more prominent in the right hemisphere. After subtracting the effects of nonshift tones (balanced for pitch and habituation status), weak but consistent differential effects of pattern‐shifts began in aT at 90–130 ms, spread to sTs and sTp at ∼130 ms, then pvpF, and finally returned to aT. Cingulate activity resembled prefrontal. Responses to pattern shifts were greatly attenuated when the same stimuli were ignored, suggesting that the initial superior temporal activity reflected an attention‐related mismatch negativity. The prefrontal activity at ∼230 ms corresponded in latency and task correlates with simultaneously recorded event‐related potential components N2b and P3a; the subsequent temporal activity corresponded to the P3b. These results were confirmed in sensors specific for frontal or temporal cortex, and thus are independent of the inverse method used. Overall, these results suggest that auditory working memory for temporal patterns begins with detection of the pattern change by an interaction of anterior and superior temporal structures, followed by identification of the event and its consequences led by posteroventral prefrontal and cingulate cortices, and finally, definitive encoding of the event in anterior temporal areas. Hum Brain Mapp, 2011. © 2010 Wiley‐Liss, Inc.
The effect of private health insurance on medical care utilization and self‐assessed health in Germany
Authors: Hullegie Patrick , Klein Tobias J.
Published: July 2010

In Germany, employees are generally obliged to participate in the public health insurance system, where coverage is universal, co‐payments and deductibles are moderate, and premia are based on income. However, they may buy private insurance instead if their income exceeds the compulsory insurance threshold. Here, premia are based on age and health, individuals may choose to what extent they are covered, and deductibles and co‐payments are common. In this paper, we estimate the effect of private insurance coverage on the number of doctor visits, the number of nights spent in a hospital and self‐assessed health. Variation in income around the compulsory insurance threshold provides a natural experiment that we exploit to control for selection into private insurance. We document that income is measured with error and suggest an approach to take this into account. We find negative effects of private insurance coverage on the number of doctor visits, no effects on the number of nights spent in a hospital, and positive effects on health. Copyright © 2010 John Wiley & Sons, Ltd.
Transoral endoscopic anatomy of the parapharyngeal space: A step‐by‐step logical approach with surgical considerations
Authors: Dallan Iacopo , Seccia Veronica , Muscatello Luca , Lenzi Riccardo , Castelnuovo Paolo , Bignami Maurizio , Montevecchi Filippo , Tschabitscher Manfred , Vicini Claudio
Published: July 2010

Background

Surgical approaches to the parapharyngeal spaces are challenging. Little is known about the transoral perspective of the anatomy of the parapharyngeal space. Thus, transoral approaches are seldom performed, and only for small‐sized tumors.

Methods

Six freshly injected cadaver heads were dissected to illustrate the transoral surgical anatomy of the parapharyngeal space.

Results

The transoral window dominates the parapharyngeal space from the medial pterygoid muscle laterally to the superior constrictor muscle medially. The stylopharyngeus and styloglossus muscles seem to be critical landmarks in this approach. Posterior to these muscles and laterally to the superior constrictor muscle, the internal carotid artery, internal jugular vein, and lower cranial nerves are identifiable.

Conclusion

This anatomic study emphasizes the critical role of the superior constrictor, styloglossus, and stylopharyngeus muscles and highlights the concept of a logical step by step technique that allows the identification of important structures and the creation of safe surgical corridors. © 2010 Wiley Periodicals, Inc. Head Neck, 2011