bluuebunny/crossref_metadata_2025 huggingface dataset:
A method for simultaneously improving the flame retardancy and toughness of PLA
Authors: Song Yan‐Peng , Wang De‐Yi , Wang Xiu‐Li , Lin Ling , Wang Yu‐Zhong
Published: July 2010

In order to modify the brittleness and flame retardant properties of poly(lactic acid) (PLA), a series of flame retardant toughened PLA composites were prepared using poly(ethylene glycol) 6000 (PEG6000) as a toughening and charring agent together with ammonium polyphosphate (APP) as an acid source and blowing agent. The fire and thermal behavior of PLA/PEG/APP composites was evaluated by limiting oxygen index (LOI), UL‐94, cone calorimeter, and thermogravimetric analysis (TGA). The results showed that the PLA/PEG/APP system had good charring ability and could improve the flame retardancy of PLA. When the content of APP in the composites was more than 5 wt%, all samples could reach UL‐94 V‐0 rating. The results of mechanical property tests demonstrated that the brittleness of PLA was also improved after blended with PEG6000. All the PLA/PEG/APP composites with an APP content of less than 10 wt% showed an obvious neck and fracture behavior, that is, the tensile behavior of PLA was changed from brittle to ductile. Copyright © 2010 John Wiley & Sons, Ltd.
Covalent VEGF protein immobilization on resorbable polymeric surfaces
Authors: Edlund U. , Sauter T. , Albertsson A.‐C.
Published: July 2010

Vascular endothelial growth factor type protein (VEGF), a potent angiogenic effector molecule, was successfully covalently immobilized onto the surfaces of the resorbable polymers poly(L‐lactic acid) (PLLA) and poly(ε‐caprolactone) (PCL) through a three‐step strategy. The surfaces were first covalently grafted with poly(acrylic acid) using non‐destructive and solvent free vapor‐phase grafting. A diamine spacer was coupled to the carboxylic acid pendant groups on the graft chains using EDC/NHS chemistry and VEGF was finally covalently attached to the amine linkers. The chemistry and topography of the modified substrates were quantitatively and qualitatively verified with XPS, ATR‐FTIR, UV–VIS, SEM, and ELISA. Copyright © 2010 John Wiley & Sons, Ltd.
Improvement of multicrystalline silicon solar cells by a low temperature anneal after emitter diffusion
Authors: Rinio Markus , Yodyunyong Arthit , Keipert‐Colberg Sinje , Mouafi Yves Patrick Botchak , Borchert Dietmar , Montesdeoca‐Santana Amada
Published: July 2010

The influence of an annealing step at about 500 °C after emitter diffusion of multicrystalline solar cells is investigated. Neighboring wafers from a silicon ingot were processed using different annealing durations and temperatures. The efficiency of the cells was measured and detailed light beam induced current measurements were performed. These show that mainly areas with high contents of precipitates near the crucible walls are affected by the anneal. An efficiency increase from 14.5 to 15.4% by a 2 h anneal at 500 °C was observed. The effect seems to be more likely external than internal gettering. Copyright © 2010 John Wiley & Sons, Ltd.
Soiling and other optical losses in solar‐tracking PV plants in navarra
Authors: García Miguel , Marroyo Luis , Lorenzo Eduardo , Pérez Miguel
Published: July 2010

Field data of soiling energy losses on PV plants are scarce. Furthermore, since dirt type and accumulation vary with the location characteristics (climate, surroundings, etc.), the available data on optical losses are, necessarily, site dependent. This paper presents field measurements of dirt energy losses (dust) and irradiance incidence angle losses along 2005 on a solar‐tracking PV plant located south of Navarre (Spain). The paper proposes a method to calculate these losses based on the difference between irradiance measured by calibrated cells on several trackers of the PV plant and irradiance calculated from measurements by two pyranometers (one of them incorporating a shadow ring) regularly cleaned. The equivalent optical energy losses of an installation incorporating fixed horizontal modules at the same location have been calculated as well. The effect of dirt on both types of installations will accordingly be compared. Copyright © 2010 John Wiley & Sons, Ltd.
The effects of spectral evaluation of c‐Si modules
Authors: Simon Michael , Meyer Edson L.
Published: July 2010

Outdoor spectral measurements in sub‐Sahara, South Africa in particular have not been documented probably due to lack of data or lack of proper methodologies for quantifying the spectral effects on photovoltaic performance parameters. Crystalline‐Si modules are widely used for system designs in most cases based on the data provided from indoor measurements or from maritime northern hemispheric conditions. As a result of this, PV systems fail to deliver their intended maximum power output. In this study, a methodology for quantifying outdoor spectral effects of c‐Si modules commonly found in the African continent is presented. The results of three crystalline‐Si modules indicate that these modules are affected as the spectrum shifts during seasons although these devices are perceived (without outdoor data) that their performance is not influenced by the seasonal changes in outdoor spectrum. Copyright © 2010 John Wiley & Sons, Ltd.
Fill factor analysis of solar cells' current–voltage curves
Authors: Greulich Johannes , Glatthaar Markus , Rein Stefan
Published: July 2010

After completion of the solar cell manufacturing process the current–density versus voltage curves (J(U) curves) are measured to determine the solar cell's efficiency and the mechanisms limiting the efficiency. An accurate and robust analysis of the measured curves is essential. In this work it is shown that fitting the two‐diode model is inappropriate to quantify recombination in the space charge region and ohmic losses due to series resistance. Three fill factors, namely the fill factor of the illuminated J(U) curve, the pseudo fill factor of the sunsVoc curve and the ideal fill factor of the single diode model, are the base of a quick loss analysis that is evaluated in the present paper. It is shown that for an accurate analysis the distributed character of the series resistance and the network character of the solar cell cannot be neglected. An advanced current–voltage curve analysis including fill factors and fit is presented. Copyright © 2010 John Wiley & Sons, Ltd.
Four‐junction spectral beam‐splitting photovoltaic receiver with high optical efficiency
Authors: Mitchell Bernhard , Peharz Gerhard , Siefer Gerald , Peters Marius , Gandy Tobias , Goldschmidt Jan Christoph , Benick Jan , Glunz Stefan W. , Bett Andreas W. , Dimroth Frank
Published: July 2010

A spectral beam‐splitting architecture is shown to provide an excellent basis for a four junction photovoltaic receiver with a virtually ideal band gap combination. Spectrally selective beam‐splitters are used to create a very efficient light trap in form of a 45° parallelepiped. The light trap distributes incident radiation onto the different solar cells with an optical efficiency of more then 90%. Highly efficient solar cells including III–V semiconductors and silicon were fabricated and mounted into the light trapping assembly. An integrated characterization of such a receiver including the measurement of quantum efficiency as well as indoor and outdoor I–V measurements is shown. Moreover, the optical loss mechanisms and the optical efficiency of the spectral beam‐splitting approach are discussed. The first experimental setup of the receiver demonstrated an outdoor efficiency of more than 34% under unconcentrated sunlight. Copyright © 2010 John Wiley & Sons, Ltd.
Solvent effects of ionic liquids: investigation of ferrocenes as electrochemical probes
Authors: Bizzarri Claudia , Conte Valeria , Floris Barbara , Galloni Pierluca
Published: July 2010

The redox potentials of ferrocene and decamethylferrocene were determined in a number of molecular and ionic solvents and used as a probe for polarity of room temperature ionic liquids (ILs). No macroscopic solvent property is simply related to redox potentials. Single empirical solvent parameters also are not able to describe the differences in potentials. Instead, Kamlet–Taft multiparameter relationship fits well ferrocenes redox potentials variation, with both molecular solvents and ILs, well describing specific solvent–solute interactions with the two probes. Copyright © 2010 John Wiley & Sons, Ltd.
Anionic polymerization of N,N‐dialkyl‐2‐methylenebut‐3‐enamide: Effect of alkyl substituents on polymerization behavior
Authors: Takenaka Katsuhiko , Shibata Natsuyo , Oshikiri Akihiko , Miya Masamitsu , Takeshita Hiroki , Shiomi Tomoo
Published: July 2010

Anionic polymerizations of three 1,3‐butadiene derivatives containing different N,N‐dialkyl amide functions, N,N‐diisopropylamide (DiPA), piperidineamide (PiA), and cis‐2,6‐dimethylpiperidineamide (DMPA) were performed under various conditions, and their polymerization behavior was compared with that of N,N‐diethylamide analogue (DEA), which was previously reported. When polymerization of DiPA was performed at −78 °C with potassium counter ion, only trace amounts of oligomers were formed, whereas polymers with a narrow molecular weight distribution were obtained in moderate yield when DiPA was polymerized at 0 °C in the presence of LiCl. Decrease in molecular weight and broadening of molecular weight distribution were observed when polymerization was performed at a higher temperature of 20 °C, presumably because of the effect of ceiling temperature. In the case of DMPA, no polymer was formed at 0 °C and polymers with relatively broad molecular weight distributions (Mw/Mn = 1.2) were obtained at 20 °C. The polymerization rate of PiA was much faster than that of the other monomers, and poly(PiA) was obtained in high yield even at −78 °C in 24 h. The microstructure of the resulting polymers were exclusively 1,4‐ for poly(DMPA), whereas 20–30% of the 1,2‐structure was contained in poly(DiPA) and poly(PiA). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3714–3721, 2010
Synthesis and luminescence of poly(phenylacetylene)s with pendant iridium complexes and carbazole groups
Authors: Vicente José , Gil‐Rubio Juan , Zhou Guijiang , Bolink Henk J. , Arias‐Pardilla Joaquín
Published: July 2010

Poly(phenylacetylene)s containing pendant phosphorescent iridium complexes have been synthesized and their electrochemical, photo‐ and electroluminescent properties studied. The polymers have been synthesized by rhodium‐catalyzed copolymerization of 9‐(4‐ethynylphenyl)carbazole (CzPA) and phenylacetylenes (C∧N)2Ir(κ2‐O,O′‐MeC(O)CHC(O)C6H4CCH‐4) (C∧N = κ2‐N,C1‐2‐(pyridin‐2‐yl)phenyl (IrppyPA) or κ2‐N,C1‐2‐(isoquinolin‐1‐yl)phenyl (IrpiqPA)). In addition, organic poly(phenylacetylene)s with pendant carbazole groups have been synthesized by rhodium‐catalyzed copolymerization of CzPA and 1‐ethynyl‐4‐pentylbenzene. Complex (C∧N)2Ir(κ2‐O,O′‐MeC(O)CHC(O)Ph) (IrpiqPh; C∧N = 2‐(isoquinolin‐1‐yl)phenyl‐κ2‐N,C1) was prepared and characterized. While the copolymers of the Irppy series were weakly phosphorescent, those of the Irpiq series displayed at room temperature intense emissions from the carbazole (fluorescence) and iridium (phosphorescence) emitters, being the latter dominant when the spectra were recorded using polymer films. Triple layer OLED devices employing copolymers of the Irpiq series or the model complex IrpiqPh yielded electroluminescence with an emission spectra originating from the iridium complex and maximum external quantum efficiencies of 0.46% and 2.99%, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3744–3757, 2010
Hydrolytic degradation of polyisobutylene and poly‐L‐lactide–based multiblock copolymers
Authors: Ojha Umaprasana , Kulkarni Pallavi , Cozzens David , Faust Rudolf
Published: July 2010

The hydrolytic degradation of a series of poly‐L‐lactide (PLLA)‐polyisobutylene (PIB) multiblock copolymers was studied in phosphate buffer solution (pH = 7.4) at 37 °C. The multiblock copolymers were synthesized by chain extension of PLLA‐b‐PIB‐b‐PLLA triblock copolymers, which were obtained by ring‐opening polymerization of L‐lactide initiated by hydroxyallyl telechelic PIB. The degradation strongly depended on the PLLA segment length. At constant PIB segment length, the multiblock copolymer with the shortest PLLA segment length (DPn = 10), showed significant weight loss after 8 weeks, whereas weight loss for DPn = 36 was only observed after 24 weeks. The gel‐permeation chromatographic analysis showed a similar decrease in the number‐average molecular weight (Mn) with time further supporting the weight loss data. Dynamic mechanical analysis showed a decrease in ultimate stress and modulus with time. The crystallinity of multiblock copolymers changed significantly with degradation time as indicated from differential scanning calorimetric analysis. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3767–3774, 2010
Ring‐opening polymerization of 1‐methyltrimethylene carbonate by rare earth initiators
Authors: Ling Jun , Dai Yongbo , Zhu Yinghong , Sun Weilin , Shen Zhiquan
Published: July 2010

Ring‐opening polymerization of 1‐methyltrimethylene carbonate (MTMC) initiated by highly active single‐component rare earth tris(2,6‐di‐tert‐butyl‐4‐methylphenolate)s [Ln(OAr)3, Ln = La, Dy, Y] or yttrium isopropoxide [Y(OiPr)3] is reported for the first time. PolyMTMC (Mw = 8.4 × 104, molecular weight distributions = 1.5) initiated by La(OAr)3 at [MTMC]/[initiator] = 1000 was obtained with the yield over 99% in toluene within 1 h at 30 °C. Random and block copolymers of MTMC with ε‐caprolactone (CL), 2,2‐dimethyltrimethylene carbonate (DTC) or polyethylene glycol (PEG) including poly(MTMC‐r‐CL), poly(MTMC‐b‐CL), poly(MTMC‐r‐DTC), poly(MTMC‐b‐DTC), and poly(MTMC‐b‐PEG‐b‐MTMC) were synthesized. The differential scanning calorimetry results show that thermal behaviors of the polymers sensitively depend on their compositions and chain structures. Furthermore, the measurements of 1H‐1H COSY and density functional theory calculation are applied to investigate the mechanism. The polymerization of MTMC takes place according to a coordination‐insertion mechanism, and the ring is opened via acyl‐oxygen bond cleavage resulting in a LnO active center. There exist two ring‐opening modes of MTMC in which mode b, breaking the CH2OCO bond, is the major pathway. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3807–3815, 2010
Highly efficient and stable blue‐light‐emitting binaphthol‐fluorene copolymers: A joint experimental and theoretical study of the main‐chain chirality
Authors: An Zhongfu , Yin Jun , Shi Naien , Jiang Hongji , Chen Runfeng , Shi Huifang , Huang Wei
Published: July 2010

In a quest for the main‐chain chiral and highly stable blue‐light‐emitting π‐conjugated polymers, a novel series of soluble conjugated random and alternating copolymers (PF‐BN) derived from fluorene and axially chiral 1,1′‐binaphthol (BINOL) were successfully synthesized by Suzuki coupling polymerization. The polymer structures, optical properties, and their electrochemical properties were investigated by 1H NMR, TGA/DSC, UV‐Vis absorption, photoluminescence, cyclic voltammetry, circular dichroism spectroscopy, and DFT calculations. The blue‐light‐emitting BINOL‐containing copolymers with proper content of BINOL show highly efficient photoluminescence and ultra highly stable light‐emission with almost unchanged fluorescent spectra after annealing at 200 °C in air for 10 h. The joint experimental and theoretical study of the main‐chain chirality reveals that (1) the chirality of BINOL can be transferred to the polymer backbone, (2) the effective conjugation length is about one BINOL and three fluorenes, (3) the main active chiral block in the copolymers is probably composed by one BINOL with the other two or three fluorenes, and (4) the dihedral angle in the PF‐BN copolymers should be larger than 105°. The incorporation of BINOL into the polyfluorene backbone is an effective way to produce highly efficient and stable blue‐light‐emitting main‐chain chiral conjugated polymer with interesting optoelectronic properties. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3868–3879, 2010
A versatile surfactant‐mediated synthetic route to gold/polyaniline derivative core/shell nanocomposites
Authors: Han Jie , Liu Yan , Wang Lu , Guo Rong
Published: July 2010

This article describes a versatile two‐step method for gold/polyaniline derivative core/shell nanocomposites with the aid of nonionic surfactant F127. First, F127 and monomer were introduced to gold colloids followed by the addition of oxidant to initiate the polymerization of monomer to afford a conducting polymer shell around each gold nanoparticle. Experimental parameters, such as kinds and concentrations of surfactant and monomer, gold core size and shape, reaction time, were systematically investigated to disclose the underground mechanisms involved in the formation of gold/polymer core/shell nanocomposites. Furthermore, Fourier transform infrared, ultraviolet–visible, X‐ray diffraction, and X‐ray photoelectron spectroscopy techniques were used to characterize the gold/polymer core/shell nanocomposites. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3903–3912, 2010
Structural development of ultra‐high strength polyethylene fibers: Transformation from kebabs to shishs through hot‐drawing process of gel‐spun fibers
Authors: Ohta Yasuo , Murase Hiroki , Hashimoto Takeji
Published: July 2010

Structural development of ultra‐high strength polyethylene fibers via hot‐drawing processes of as‐spun gel fibers was investigated by means of transmission electron microscopy. It is found that the shish‐kebabs developed in both the as‐spun and drawn fibers can be transformed continuously into the micro‐fibril structure composed mostly of the shish structure through the hot‐drawing process. The structure transformation involves a drastic decrease in diameter of the kebab plus the shish but almost no change in the shish diameter. This result suggests that the chains in the kebabs are incorporated into the shishs and consumed to extend the longitudinal dimension of the shishs during the drawing process. The proposed new deformation model well explains the relationship between the fiber morphology and their mechanical properties: the tensile strength and modulus of the fibers can be determined by the number of the shish in the fiber and the macroscopic diameter of the fiber, which are apriori determined at the spinning process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1861–1872, 2010
Effects of magnetic field on shear stress of nematic liquid crystalline polymer under simple shear flow
Authors: Fu Shu.‐F. , Wang Xuan‐zhang
Published: July 2010

The effect of magnetic fields on the shear stress of liquid crystalline polymers (LCPs) under shear flows is numerically analyzed using the Doi theory. The evolution equation for the probability density of LCP molecules is directly solved without any closure approximations. When the magnetic field is imposed on the LCPs along the shear flow, the low‐shear rate plateau of the time‐averaged generalized viscosity
$ \bar{\eta}^*(=\bar\sigma_{xy}^{*}/\dot\gamma^{*}) $
disappears, which is due to the manner of the new aligning mode observed by Fu et al. The negative first normal stress difference
$ \bar N_{1}^{*} $
becomes opposite in all the shear rate regimes with the disappearance of periodic oscillations. For the magnetic field parallel to the velocity gradient direction, the more complicated sign changes of
$ \bar N_{1}^{*} $
is investigated because of the moment caused by the magnetic field vertical to the one caused by the shear flow. The ratio
$ \bar N_{2}^{*}/\bar N_{1}^{*} $
increases with the increasing magnetic field strength. Finally, when the molecular shape parameter is considered as 0.9, the similar discussions are achieved according to the phase diagram among tumbling, wagging, and aligning modes versus the magnetic field strength. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1919–1926, 2010
Isothermal crystallization kinetics of polypropylene latex–based nanocomposites with organo‐modified clay
Authors: Raka Luljeta , Sorrentino Andrea , Bogoeva‐Gaceva Gordana
Published: July 2010

The effect of organo‐modified clay (Cloisite 93A) on the crystal structure and isothermal crystallization behavior of isotactic polypropylene (iPP) in iPP/clay nanocomposites prepared by latex technology was investigated by wide angle X‐ray diffraction, differential scanning calorimetry and polarized optical microscopy. The X‐ray diffraction results indicated that the higher clay loading promotes the formation of the β‐phase crystallites, as evidenced by the appearance of a new peak corresponding to the (300) reflection of β‐iPP. Analysis of the isothermal crystallization showed that the PP nanocomposite (1% C93A) exhibited higher crystallization rates than the neat PP. The unfilled iPP matrix and nanocomposites clearly shows double melting behavior; the shape of the melting transition progressively changes toward single melting with increasing crystallization temperature. The fold surface free energy (σe) of polymer chains in the nanocomposites was lower than that in the PP latex (PPL). It should be reasonable to treat C93A as a good nucleating agent for the crystallization of PPL, which plays a determinant effect on the reduction in σe during the isothermal crystallization of the nanocomposites. The activation energy, ΔEa, decreased with the incorporation of clay nanoparticles into the matrix, which in turn indicates that the nucleation process is facilitated by the presence of clay. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1927–1938, 2010
HRTEM observation of defect structures of β‐Ga2O3nanowires
Authors: Yang Qing , Yasuda Takahiro , Brown Paul D. , Tanaka Miyoko , Tatsuoka Hirokazu
Published: July 2010

The defect structures of β‐Ga2O3nanowires were characterized using transmission electron microscopy (TEM). Branched and jagged β‐Ga2O3nanowires were obtained by the heat treatment of gallium metal with Cu5Si powders. The growth direction of the branched nanowire is perpendicular to the (001) planes, the (001) planes of the branch nanowire, and the (110) planes of the primary nanowire face each other at the grain boundary. The jagged nanowire has a growth direction combining the [001] and$[\bar {1}01]$directions. Cu atoms were highly concentrated at the β‐Ga2O3nanowires, and the effect of impurity on the growth of β‐Ga2O3nanowires was demonstrated. The dynamic evolution of β‐Ga2O3nanowires with reference to specific morphological features was discussed in terms of the anisotropic crystalline structures of the β‐Ga2O3crystals. It is found that the structural and morphological properties of β‐Ga2O3nanowires were greatly influenced by the growth conditions, and the specific crystalline defects affected the final morphological feature of the nanowires.
Structural and magnetic characterizations of MnNiZn ferrite nanoparticles
Authors: Mane Dhanraj R. , Birajdar Damodar D. , Shirsath Sagar E. , Telugu Raghavender A. , Kadam Ram. H.
Published: July 2010

The ferrite samples of Ni0.7−xMnxZn0.3Fe2O4 (where x = 0.0–0.7 in steps of x = 0.1) were synthesized by a sol–gel autocombustion method using nitrates of respective metal ions. The synthesized samples were annealed at 600 °C for 4 h. The phase purity of the samples was investigated by X‐ray diffraction (XRD). An analysis of XRD patterns reveals the formation of single‐phase cubic spinel structure. The crystal lattice constant increases gradually with increasing x from 8.389 to 8.473 Å. The cation distribution of constituent ions shows linear dependence of Mn substitution. Based on the cation distribution obtained from XRD data, structural parameters such as lattice parameters, ionic radii of available sites, and the oxygen parameter “u” have been calculated. The trend of theoretically calculated lattice parameter with Mn content matches well with the experimentally obtained values. An initial increase followed by a subsequent decrease of saturation magnetization with increase in x is observed. Possible explanations for the observed structural and magnetic behavior with various Mn content are discussed.
Electrodeposition of transparent and conducting graphene/carbon nanotube thin films
Authors: Bittolo Bon S. , Valentini L. , Kenny J. M. , Peponi L. , Verdejo R. , Lopez‐Manchado M. A.
Published: July 2010

We report the electrophoretic deposition of graphene/single‐walled carbon nanotube hybrid films onto flexible, transparent and conducting indium tin‐oxide‐coated polyethylene terephthalate substrates. This room‐temperature solution process is completely compatible with polymeric substrates and does not require a sophisticated transfer process, allowing uniform and controllable deposition of such carbon thin films with tailored optical and electrical properties over large areas. In particular, the film thickness, optical transparency and electrical conductivity can be modified by the deposition time and the obtained films span several square centimetres in area.
Design of a hierarchical structure of ZnO by electrochemistry for ZnO‐based dye‐sensitized solar cells
Authors: Haller Servane , Suguira Takashi , Lincot Daniel , Yoshida Tsukasa
Published: July 2010

A hierarchical structure with a large surface area and an efficient carrier transfer of the electrons has been developed. This structure is composed of zinc oxide nanorods surrounded by nanoporous zinc oxide and is obtained by a two‐step cathodic electrodeposition. Different geometries could be identified whether the hierarchical structures have grown enough to join themselves or not. The first moments of the electrodeposition of the nanoporous structure on the nanorods have been investigated and it is revealed that a nanoporous layer is epitaxially deposited. Preliminary tests of dye‐sensitized solar cell were prepared with this structure that confirmed the interest of the concept.

magnified image

Schematic figure of principle.
GaN‐based ultraviolet light‐emitting diodes with multifinger contacts
Authors: Rodríguez Hernán , Lobo Neysha , Einfeldt Sven , Knauer Arne , Weyers Markus , Kneissl Michael
Published: July 2010

GaN‐based ultraviolet light‐emitting diodes with identical contact areas but different contact shapes are studied. Interdigitated multifinger contacts with reduced finger width result in a lower series resistance and a thermal roll‐over of the output power at higher cw currents in comparison to square‐shaped contacts. Under pulsed operation, the external quantum efficiency in these devices is increased due to a reduction of the efficiency droop at elevated currents. Simulations of the current distribution explain the experimental data with an improved uniformity of the current density in multifinger contacts as current crowding at the contact edges is largely suppressed.
Reactions on the SiC(0001) √3 × √3 R30° surface after Ti deposition and annealing
Authors: Johansson L. I. , Virojanadara C.
Published: July 2010

The interactions of thin Ti layers deposited on the SiC(0001) √3 × √3 R30° surface at room temperature and after annealing at temperatures from 450 to 1200 °C was investigated using photoemission and LEED. Chemically shifted components were revealed in the Si 2p spectrum and found to be more intense and pronounced than the shifted component in the C 1s spectrum after Ti deposition and annealing. The relative intensity of these shifted components were found to increase initially upon annealing at temperatures up to around 700 °C. At temperatures above 800 °C only the shifted component in the C 1s spectrum remained which indicate that only TiC then remains on the surface. At annealing temperatures of 600–700 °C formation of the ternary Ti3SiC2 phase and an interface TiSix layer is suggested from shifts and relative intensities observed for these components. That the formation and decomposition of the ternary phase occurs at a considerably lower temperature than earlier reported is attributed to the fact that we investigated the interaction of considerably thinner Ti layers with SiC substrates than in those earlier reported studies.
A bibliography of the literature on process capability indices: 2000–2009
Authors: Yum Bong‐Jin , Kim Kwan‐Woo
Published: July 2010

This paper contains a bibliography of approximately 530 journal papers and books on process capability indices for the period 2000–2009. The related literature is classified into four major categories, namely, books, review/overview papers, theory‐ and method‐related papers, and special applications. Theory‐ and method‐related papers are further classified into univariate and multivariate cases, and special applications include acceptance sampling plans, supplier selection, and tolerance design and other optimizations. Copyright © 2010 John Wiley & Sons, Ltd.
The development of a robust design methodology for time‐oriented dynamic quality characteristics with a target profile
Authors: Goethals Paul L. , Cho Byung Rae
Published: July 2010

Innovative engineering techniques are often sought within the manufacturing environment to improve product quality and promote more cost‐effective strategies. Robust design methods are frequently used to serve this purpose, with the objective of minimizing the variability inherent within a particular process or system. A review of the literature suggests that most robust design research involves the study of static quality characteristics, given a pre‐defined specification interval or region and target value. In addition to proposing a methodology for working with dynamic quality characteristics where the specifications and target value may change over time, this paper offers two other distinct contributions. First, those researchers who have examined dynamic systems traditionally consider the effects of a signal factor on a response variable on the identification of optimal factor settings. In contrast, this paper will consider the effects of a quality characteristic changing over time, thus removing the need to confine the problem to signal–response systems. Furthermore, most researchers consider the optimization of the process mean according to the costs of non‐conforming to an established specification interval or region. This paper, however, utilizes a methodology involving the simultaneous optimization of the process mean and variance while expanding the problem to consider a loss in quality attributed to deviation from a target value over time. Copyright © 2010 John Wiley & Sons, Ltd.
Unconventional H‐bonds: SH···N interaction
Authors: Solimannejad Mohammad , Scheiner Steve
Published: July 2010

Quantum calculations at the MP2/aug‐cc‐pVDZ level are used to analyze the SH···N H‐bond in complexes pairing H2S and SH radical with NH3, N(CH3)3, NH2NH2, and NH2N(CH3)2. Complexes form nearly linear H‐bonds in which the SH covalent bond elongates and shifts its stretching frequency to the red. Binding energies vary from 14 kJ/mol for acceptor NH3to a maximum of 22 kJ/mol for N(CH3)3and N(CH3)2NH2. Analysis of geometric, vibrational, and electronic data indicate that the SH···N interaction involving SH is slightly stronger than that in which the closed‐shell H2S serves as donor. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Managing municipal solid waste from a system perspective: A comparative study of Dalian, China and Waterloo, Canada
Authors: Chen Xudong , Haight Murray E. , Geng Yong , Fujita Tsuyoshi
Published: July 2010

In China, one of the challenges on managing solid wastes is how to realize waste reduction, reuse and recycling while maintaining rapid development, leading to a demand for an Integrated Solid Waste Management (ISWM) approach. A practical way to improve ISWM in developing countries is to learn from successful experiences in developed countries. Hence, systematic comparisons that reflect the complexity of ISWM systems in different contexts are needed. This paper takes a system perspective to compare and contrast two cases, the Region of Waterloo in Canada and Dalian in China, exploring the reasons for the different management approaches between the two cases. The results show that in some aspects, differences between the two waste management systems are tightly linked to their respective social and economic contexts, which can hardly be changed, whereas other differences can be attributed mainly to management strategies and tools. Suggestions are provided on waste planning, the development of waste diversion programs and waste treatment industries, the design of new programs, and the role of the local government. Copyright © 2010 John Wiley & Sons, Ltd and ERP Environment.
Sustainable consumption: Green purchasing behaviours of urban residents in China
Authors: Liu Xianbing , Wang Can , Shishime Tomohiro , Fujitsuka Tetsuro
Published: July 2010

Green purchasing (GP) is an important part of sustainable consumption, which reduces the impact of society on the environment. As few studies of people's GP behaviours exist for China, this paper tries to close the gap by exploring GP behaviours of urban residents in Suzhou city, Jiangsu Province. A total of 336 valid samples in a questionnaire survey are used for the analysis. Nearly half of the respondents have seldom bought green products, confirming a low level of residential GP practices. The path analysis clarifies the cause and effect linkages between the predicting variables and GP behaviours. Environmental attitudes, especially perception of self‐responsibility, greatly influence intention of GP behaviours. The available information of green products significantly determines people's actual GP behaviours. This study addresses the importance of environmental education in enhancing the public's environmental responsibility in China. More information on green products should be distributed to assist in GP practices of consumers. Copyright © 2010 John Wiley & Sons, Ltd and ERP Environment.
Food miles to assess sustainability: A revision
Authors: Van Passel Steven
Published: July 2010

Sustainability assessment is an essential process in our aim to reach a more sustainable production and consumption pattern. This research revises the food miles concept as a guiding tool to assess sustainability. Food miles measure the distance that food travels from where it is grown or raised to where it is consumed. Three different concepts to assess sustainability are described: (i) food miles, (ii) enhanced food miles, (iii) food chain sustainability. An illustrative case study shows that there is a strong danger of oversimplification when using food miles as an assessment tool. Second, the food miles concept can be enhanced with all relevant transport externalities taking into account different transport modes and transport (in)efficiency. Third, all relevant economic, social, and ecological aspects should be taken into account. Besides transport externalities, also externalities caused by food production, food packaging, food marketing, and food consumption should be incorporated. Moreover, the trade‐off with development goals cannot be neglected. As a consequence, there is a strong danger of incommensurability as the result of different sustainability model assumptions and unclear system boundaries. Nevertheless, sustainability assessment can enrich policy making and support tailored policy measures to improve food chain sustainability. Copyright © 2010 John Wiley & Sons, Ltd and ERP Environment.
Digital credentials with privacy‐preserving delegation
Authors: Knox D. A. , Adams C.
Published: July 2010

This paper extends digital credentials, a cryptographic scheme that provides provably secure, private, attribute certificates. We give a method for the delegation of these credentials, which allows the delegator to reveal a subset of his/her credentials to a delegatee, who in turn can control revelation of this subset to a verifier. Our method also supports blinded showing of credentials to a specified verifier in order to hide the credentials from the delegatee, when desired. Privacy is preserved in all cases under a strong attack model that includes collusion between an attacker (Malice) and the Certification Authority that issued the credentials. Copyright © 2010 John Wiley & Sons, Ltd.
Verifying position and velocity for vehicular ad‐hoc networks
Authors: Weerasinghe Hesiri D. , Tackett Raymond , Fu Huirong
Published: July 2010

In the near future, vehicle‐to‐vehicle and vehicle‐to‐roadside infrastructure communications will enable numerous applications, such as collision avoidance, traffic management, location‐based services, and infotainment for the automobile field. Position and velocity play important roles in these applications such as collision avoidance. Forged position or velocity information will make a severe impact on both performance and security of the vehicular ad‐hoc network (VANET). The main challenges in developing secure position and velocity schemes for VANETs are the highly dynamic environment and cost constraints. In this paper, we propose a position and velocity verification scheme. Then via ns‐2, we simulate the proposed scheme in various vehicular mobility environments including rural, urban and Manhattan. Finally, we evaluate the proposed scheme for both position and velocity verifications with automotive grade differential global positioning system (DGPS) and intentionally induced errors as well. The performance evaluation results show that (1) our scheme is very precise in both position and velocity verifications and (2) the proposed scheme is very robust in position verification for rural, urban and Manhattan scenarios even if the introduced errors are in the order of 10 m. Copyright © 2010 John Wiley & Sons, Ltd.
A survey of authentication schemes for vehicular ad hoc networks
Authors: Riley Marshall , Akkaya Kemal , Fong Kenny
Published: July 2010

Vehicular ad hoc networks (VANETs) are planned to be deployed within the next decade to improve driver safety, prevent collisions, and provide traffic optimization. Recent years have witnessed an increasing interest in the security schemes for VANETs as this area was relatively less explored compared to other areas such as medium access and routing. In particular, efficient authentication of the messages in a VANET with other desirable security features have been heavily studied. However, there are still several issues to be addressed before such authentication mechanisms can be readily and widely used in real‐life deployments. In this paper, we examine several proposed authentication solutions and categorize them based on certain criteria. We provide a comparison of the advantages and disadvantages of the proposed schemes identifying their suitability under various conditions. Finally, to foster further research in the area, we address some of the challenges that need to be tackled in the future in order to realize the deployment of VANETs. Copyright © 2010 John Wiley & Sons, Ltd.
The Synthesis of Anatase TiO2 Nanoparticles by Solvothermal Method using Ionic Liquid as Additive
Authors: Lin Hechun , de Oliveira Peter W. , Grobelsek Ingrid , Haettich Aude , Veith Michael
Published: July 2010

The solvothermal reactions of Ti(OiPr)4 in alcohol using ionic liquid as additive were investigated. In the presence of [BMIM][Cl], [BMIM][Br], [BMIM][NTf2], [BMIM][SO3Me], [BMIM][SO4Me], or [BMIM][OTf] (BMIM = 1‐Butyl‐3‐methylimidazolium), pure anatase nanoparticles were obtained. The controlled hydrolysis of Ti(OiPr)4 in the presence of ionic liquids to form titanium oxo clusters plays a key role in the formation of anatase nanostructures, and ionic liquids can be repeatedly used to synthesise anatase nanoparticles. However, in the presence of [BMIM][PF6], [BMIM]2[Ti(OH)6] was obtained by an anion exchange reaction.
New Development in Rare Earth Metal Complexes Containing Anionic Bis(imino)pyrrolyl and Bis(phosphanyl)amide Ligands
Authors: Li Tianshu , Jenter Jelena , Roesky Peter W.
Published: July 2010

Rare earth element complexes with the very bulky 2,5‐bis{N‐(2,6‐diisopropylphenyl)iminomethyl}pyrrolyl and the sterically less demanding bis(phosphanyl)amide ligand, (PPh2)2N– in the coordination sphere are reviewed in this research report. The coordination chemistry, the reactivity, and the catalytic application of the corresponding complexes are discussed.
Synthesis, Structure, and Reactivity of the Sterically Crowded Complex (C5Me4SiMe3)3U
Authors: Siladke Nathan A. , Ziller Joseph W. , Evans William J.
Published: July 2010

The unusual chemistry obtainable from sterically crowded (C5R5)3M complexes has been explored with M = U and (C5Me4SiMe3)1–, a ligand that has independently provided unexpected uranium chemistry. (C5Me4SiMe3)2UMe2 (1), is reduced by potassium to generate the “ate” salt (C5Me4SiMe3)2UMe2K (2), which reacts with [HNEt3][BPh4] to yield the cationic species [(C5Me4SiMe3)2U][BPh4] (3). KC5Me4SiMe3 reacts with 3 in benzene to form (C5Me4SiMe3)3U, (4). The structure of 4 shows that the displacement of the methyl groups from the cyclopentadienyl ring planes, a useful indicator of steric crowding, is the largest ever observed in a (C5R5)3M complex. The reactivity of 4 is consistent with this structural indicator in that it engages in THF ring opening to form (C5Me4SiMe3)2UO[(CH2)4(C5Me4SiMe3)](THF).
The role of the soil seed and seedling bank in the regeneration of diverse plant communities in the subtropical Ailao Mountains, Southwest China
Authors: Li Xiaoshuang , Liu Wenyao , Tang Cindy Q.
Published: July 2010

We compared species composition and diversity of the soil seed and seedling banks in three secondary vegetation types (shrubland, Populus bonatii forest, Lithocarpus regrowth forest) and a primary old‐growth forest in the subtropical Ailao Mountains of southwestern China to clarify the importance of seed and seedling banks for forest dynamics. The average species richness was the highest in soil samples from the shrubland (26.80 ± 1.98), and the lowest from the primary forest (9.93 ± 0.50). The density of germinable tree seeds increased from the secondary vegetation to the primary forest, and the density of shrub, forb, and graminoid seeds decreased significantly. The most abundant seedlings recorded in soil samples were light‐demanding species in the shrubland and Populus bonatii forest. For ground flora, the number of shrub seedlings strongly decreased with the increase in stand age, and shade‐tolerant tree seedlings tended to increase. The species similarity between the seed bank and the aboveground vegetation in all sites was low (Sørensen's index = 0.11–0.33), however, the shrubland had higher similarity compared with the other three plant communities. In the primary forest, light‐demanding woody species dominated in soil seed banks, while shade‐tolerant species dominated in the overstory and the forest floor. In the primary forest, seedlings of dominant tree species were rare in the understory, and no seeds of the dominant species were found in the soil. Results indicated that the early stages of vegetation recovery should take into account the possibility of recovering soil seed bank processes. However, colonization and establishment of tree seedlings will be difficult once a primary forest is destroyed.
Redox regulation of the tumor suppressor PTEN by glutathione
Authors: Kim Yujeong , Song Yong Bhum , Kim Tae-Youl , Kim Inyoung , Han Seong-Jeong , Ahn Younghee , Cho Seung-Hyun , Choi Cheol Yong , Chay Kee-Oh , Yang Sung Yeul , Ahn Bong Whan , Huh Won-Ki , Lee Seung-Rock
Published: July 2010

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) expressed in Saccharomyces cerevisiae was reversibly oxidized by hydrogen peroxide and reduced by cellular reductants. Reduction of hPTEN was delayed in each of S. cerevisiae gsh1Δ and gsh2Δ mutants. Expression of γ‐glutamylcysteine synthetase Gsh1 in the gsh1Δ mutant rescued regeneration rate of hPTEN. Oxidized hPTEN was reduced by glutathione in a concentration‐ and time‐dependent manner. Glutathionylated PTEN was detected. Incubation of 293T cells with BSO and knockdown expression of GCLc in HeLa cells by siRNA resulted in the delay of reduction of oxidized PTEN. Also, in HeLa cells transfected with GCLc siRNA, stimulation with epidermal growth factor resulted in the increase of oxidized PTEN and phosphorylation of Akt. These results suggest that the reduction of oxidized hPTEN is mediated by glutathione.
SOFT REPRESSION AND MOBILIZATION: THE CASE OF TRANSNATIONAL ACTIVISM OF DANISH MUSLIMS DURING THE CARTOONS CONTROVERSY
Authors: Lindekilde Lasse
Published: July 2010

For several months after the September 2005 publication of twelve cartoons of the Prophet Muhammad in the Danish newspaperJyllands-Posten, the debate was largely confined to a Danish context. Early international protests of the cartoons were voiced by government officials in several countries, including Pakistan, Iran, and Egypt. However, until late December 2005, in what I will call phase one of the controversy, Danish Muslims fought a primarily domestic battle for some kind of recognition from the newspaper and the Danish government that the cartoons had hurt religious feelings. In October 2005 an ad hoc coalition of Danish Muslim organizations, with The Community of Islamic Faith (Det Islamiske Trossamfund) and its affiliated imams at the lead, tried to put pressure on the Danish government through ambassadors from Muslim countries posted in Denmark. The ambassadors' request for a meeting with the Danish prime minister was turned down, as were other attempts by Danish Muslims to raise claims with the government.
The Middle Eastern Christian as Agent
Authors: Rowe Paul S.
Published: July 2010

The greatest accomplishment of the past ten to twenty years of scholarship on Christian groups in Middle Eastern states is the way scholars have recognized the agency of a population long objectified in both academic and polemical circles. Christians have long been viewed as the object of other actors. For some, they were mere products of Muslim societies that imposed upon them the debatably restricted or protected status ofahl al-dhimma. For others, they were the appendages of external forces determined to use them as devices of their interests. The concerns of such external forces only contributed to Christians' portrayal as vehicles of imperialism. Although these tropes persist, over the last several years many scholars have begun to explore the ways in which Arab and other Middle Eastern Christians operate as subjects in their own right.
Finding a Platform: Studying the Copts in the 19th and 20th Centuries
Authors: van Doorn-Harder Nelly
Published: July 2010

Research on the Copts of Egypt has developed especially rapidly in new directions during the past twenty years. Having started as a corollary of Egyptology, it is advancing from the study of the early Christian centuries to include medieval, early modern, and contemporary Coptic Studies. Concurrently, Coptic issues are being inserted into studies of Egypt in general. Publications on the 19th century mostly ignored Copts, but they were given stereotypical cameo appearances in the prolific research on the profound transformations in 20th-century Egyptian society.
Christians in the Middle East: A New Subfield?
Authors: McCallum Fiona
Published: July 2010

The topic of Christians in the Middle East appears to be enjoying a growing vitality within Middle East studies. This is not to say that scholarship ignored the subject in the past, but it was rarely seen as an independent area of study. Works tended to focus on the historical origins, faith, and rites of the different churches within Eastern Christianity. Those that looked specifically at Christian communities tended to concentrate on their relations with other groups, especially in the context of a minority framework. Some interdisciplinary volumes such as those edited by Andrea Pacini and Anthony O'Mahony moved beyond this limited approach to cover a wider range of issues, but several of the contributions retained this descriptive tendency rather than relating directly to theoretical debates within different disciplines.