bluuebunny/crossref_metadata_2025 huggingface dataset:
Dissolution of waste plastics in biodiesel
Authors: Zhang Ying , Mallapragada Surya K. , Narasimhan Balaji
Published: November 2009

The dissolution behavior of polystyrene (PS) and low‐density polyethylene (LDPE) in biodiesel was investigated with an eye towards developing methods to dispose waste plastics by burning them with fuel. To complement and guide the experimental investigations, molecular dynamics simulations were performed to calculate solubility parameters, cohesive energy densities, Flory‐Huggins χ parameters and phase diagrams of the target systems. Dissolution kinetics of PS and LDPE in methyl esters was monitored by gravimetry, from which parameters such as dissolution rates, activation energies, and scaling indices were estimated. The shear viscosity of the polymer solutions was measured to ascertain their suitability as fuel mixtures. The dissolution of PS in biodiesel appears to be controlled by the diffusion of polymer chains through a boundary layer adjacent to the polymer/solvent interface. Taken together, the experimental and modeling studies provide a predictive toolbox to design biodiesels of different compositions that will dissolve commodity polymers such as PS and LDPE to be used as fuels in engines. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers
Hysteresis measurements and dynamic mechanical characterization of functionally graded natural rubber–carbon black composites
Authors: Ahankari S.S. , Kar Kamal K.
Published: November 2009

Functionally graded polymer composites (FGPCs) were prepared by construction based layering method employing natural rubber (NR) as a matrix and carbon black (CB) in graded form. CB particles were graded along the rectangular geometry polymer matrix comprising the variation of particle volume fraction along thickness direction. These FGPCs were characterized through hysteresis measurements and compared with uniformly dispersed polymeric composites (UDPCs) maintaining the same average amount of filler. Dynamic mechanical properties of these FGPCs and UDPCs were also compared. Dynamic mechanical characterization revealed that FGPCs show much higher storage modulus than the corresponding UDPCs for any given combination of stacking sequence. Loss tangent of FGPCs was also observed to be lesser when compared to UDPCs leading to less hysteretic losses followed by lesser heat buildup in the composite. Hysteresis measurements accorded with the results of dynamic mechanical characterization. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers
Right‐wing authoritarianism and social dominance orientation and the dimensions of generalized prejudice: A longitudinal test
Authors: Asbrock Frank , Sibley Chris G. , Duckitt John
Published: November 2009

A Dual Process Model (DPM) approach to prejudice proposes that there should be at least two dimensions of generalized prejudice relating to outgroup stratification and social perception, which should be differentially predicted by Right‐Wing Authoritarianism (RWA) and Social Dominance Orientation (SDO). The current study assessed the causal effects of SDO and RWA on three dimensions of prejudice using a full cross‐lagged longitudinal sample (N = 127). As expected, RWA, but not SDO, predicted prejudice towards ‘dangerous’ groups, SDO, but not RWA, predicted prejudice towards ‘derogated’ groups, and both RWA and SDO predicted prejudice towards ‘dissident’ groups. Results support previously untested causal predictions derived from the DPM and indicate that different forms of prejudice result from different SDO‐ and RWA‐based motivational processes. Copyright © 2009 John Wiley & Sons, Ltd.
β‐Lactam functionalized poly(isoprene‐b‐ethylene oxide) amphiphilic block copolymers
Authors: Kaditi Eleni , Pispas Stergios
Published: November 2009

Amphiphilic block copolymers containing β‐lactam groups on the polyisoprene block were synthesized from poly(isoprene‐b‐ethylene oxide) (IEO) diblock copolymer precursors, prepared by anionic polymerization. β‐Lactam functionalization was achieved via reaction of the polyisoprene (PI) block with chlorosulfonyl isocyanate and subsequent reduction. The resulting block copolymers were molecularly characterized by SEC, FTIR, and NMR spectroscopies and DSC. Functionalization was found to proceed in high yields, altering the solubility properties of the PI block and those of the functionalized diblocks. Hydrogen bond formation is assumed to be responsible for the decreased crystallinity of the poly(ethylene oxide) block (PEO) in the bulk state as indicated by DSC measurements. The self‐assembly behavior of the β‐lactam functionalized poly(isoprene‐b‐ethylene oxide) copolymers (LIEO) in aqueous solutions was studied by dynamic light scattering (DLS), static light scattering (SLS), fluorescence spectroscopy, and atomic force microscopy (AFM). Nearly spherical loose aggregates were formed by the LIEO block copolymers, having lower aggregation numbers and higher cmc values compared to the IEO precursors, as a result of the increased polarity of the β‐lactam rings incorporated in the PI blocks. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 24–33, 2010
Synthesis, micelle formation, and bulk properties of poly(ethylene glycol)‐b‐poly(pentafluorostyrene)‐g‐polyhedral oligomeric silsesquioxane amphiphilic hybrid copolymers
Authors: Hussain H. , Tan B.H. , Mya K. Y. , Liu Y. , He C. B. , Davis Thomas P.
Published: November 2009

The synthesis, micelle formation, and bulk properties of semifluorinated amphiphilic poly(ethylene glycol)‐b‐poly(pentafluorostyrene)‐g‐cubic polyhedral oligomeric silsesquioxane (PEG‐b‐PPFS‐g‐POSS) hybrid copolymers is reported. The synthesis of amphiphilic PEG‐b‐PPFS block copolymers are achieved using atom transfer radical polymerization (ATRP) at 100 °C in trifluorotoluene using modified poly(ethylene glycol) as a macroinitiator. Subsequently, a proportion of the reactive para‐F functionality on the pentafluorostyrene units was replaced with aminopropylisobutyl POSS through aromatic nucleophilic substitution reactions. The products were fully characterized by 1H‐NMR and GPC. The products, PEG‐b‐PPFS and PEG‐b‐PPFS‐g‐POSS, were subsequently self‐assembled in aqueous solutions to form micellar structures. The critical micelle concentrations (cmc) were estimated using two different techniques: fluorescence spectroscopy and dynamic light scattering (DLS). The cmc was found to decrease concomitantly with the number of POSS particles grafted per copolymer chain. The hydrodynamic particle sizes (Rh) of the micelles, calculated from DLS data, increase as the number of POSS molecules grafted per copolymer chain increases. For example, Rh increased from ∼60 nm for PEG‐b‐PPFS to ∼80 nm for PEG‐b‐PPFS‐g‐POSS25 (25 is the average number of POSS particles grafted copolymer chain). Static light scattering (SLS) data confirm that the formation of larger micelles by higher POSS containing copolymers results from higher aggregation numbers (Nagg), caused by increased hydrophobicity. The Rg/Rh values, where Rg is the radius of gyration calculated from SLS data, are consistent with a spherical particle model having a core‐shell structure. Thermal characterization by differential scanning calorimetry (DSC) reveals that the grafted POSS acts as a plasticizer; the glass transition temperature (Tg) of the PPFS block in the copolymer decreases significantly with increasing POSS content. Finally, the rhombohedral crystal structure of POSS in PEG‐b‐PPFS‐g‐POSS was verified by wide angle X‐ray diffraction measurements. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 152–163, 2010
SET‐LRP of vinyl chloride initiated with CHBr3 and catalyzed by Cu(0)‐wire/TREN in DMSO at 25 °C
Authors: Hatano Takanori , Rosen Brad M. , Percec Virgil
Published: November 2009

The single‐electron transfer living radical polymerization (SET‐LRP) of vinyl chloride (VC) initiated with CHBr3 in dimethylsulfoxide (DMSO) at 25 °C was investigated using Cu(0) powder and Cu(0) wire as the catalyst. It was determined that living kinetics and high conversion are achieved only through the proper calibration of the ratio between Cu(0) and TREN and the concentration of VC in DMSO. For both Cu(0) powder and Cu(0) wire, optimum conversion was achieved with higher levels of TREN than reported in earlier preliminary reports and under more dilute conditions. Using these conditions, 85+% conversion of VC could be achieved with Cu(0) powder and wire to produce white poly(vinyl chloride) (PVC) with Mn = 20,000 and Mw/Mn = 1.4–1.6 in 360 min. The use of Cu(0) wire provides the most effective catalytic system for the LRP of PVC allowing for simple removal and recycling of the catalyst. In the Cu(0) wire‐catalyzed SET‐LRP of VC, the consumption of Cu(0) was monitored as a function of conversion. From these studies, it is evident that the catalyst can be recycled extensively before significant exchange of Cu(0) into Cu(II)X2 and change in catalyst surface area is observed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 164–172, 2010
Surface grafting on poly(ethylene terephthalate) track‐etched microporous membrane by activation with trifluorotriazine: Application to the biofunctionalization with GRGDS peptide
Authors: Rerat Vincent , Pourcelle Vincent , Devouge Sabrina , Nysten Bernard , Marchand‐Brynaert Jacqueline
Published: November 2009

A two‐step wet chemistry protocol has been developed for the surface derivatization of poly(ethylene terephthalate) (PET) track‐etched membrane used as cell culturing support, that is, (a) activation by trifluorotriazine (1 M in acetonitrile (ACN), 30 °C, 3 h); (b) coupling to amine‐terminated molecules, namely 3,5‐bis(trifluoromethyl)benzylamine ((F)Tag), (L)‐4,5‐[3H]‐lysine, and Gly‐Arg‐Gly‐Asp‐Ser (GRGDS) pentapeptide (10−3 M in PB‐ACN, 1:1 (v/v), 20 °C, 17 h). The grafting rates determined by X‐ray photoelectron spectroscopy, from the F/C and N/C atomic ratios, are in the range of 100–140 pmol/cm2 (apparent surface), whereas the liquid scintillation counting assays give higher values (180–230 pmol/cm2) corresponding to the open surface reactivity. PET‐g‐(F)Tag is reasonably stable under two usual sterilization conditions of biomaterials, that is, steam heating at 121 °C and γ‐irradiation at 25 kGy. On the other hand, PET‐g‐GRGDS is found to be stable only under ionization radiation (84% of remaining peptide molecules), but damaged in a large extent by the autoclave treatment (23% of remaining peptide molecules). The surfaces of the sterilized PET and PET‐g‐GRGDS samples have been characterized by water contact angle measurement and by atomic force microscopy analysis in air and under water. Comparatively to the corresponding nonsterilized surfaces, γ‐irradiated surfaces are slightly more hydrophilic and also slightly more rough and jagged. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 195–208, 2010
A quinoxaline derivative as a long wavelength photosensitizer for diaryliodonium salts
Authors: Bulut Umut , Gunbas Gorkem E. , Toppare Levent
Published: November 2009

This article reports the use of a quinoxaline derivative as a photosensitizer for diaryliodonium salt photoinitiators. 2,3‐bis(3,4‐bis(decyloxy)phenyl)‐5,8‐bis(2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐5‐yl)quinoxaline (DOPEQ), is a highly conjugated compound with strong absorption bands at wavelengths ranging from 300 to 550 nm and is shown to facilitate photoinitiated cationic polymerization of heterocyclic monomers such as oxiranes and oxetanes. The polymerizations are initiated at room temperature by using long wavelength UV light in the presence of diphenyliodonium hexafluorophosphate (Ph2I+PF). The polymerizations are monitored by optical pyrometry (OP). It is also possible to initiate photopolymerizations with ambient solar irradiation in the presence of this photosensitizer dye. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 209–213, 2010
Synthesis and characterization of multiblock copolymers based on hydrophilic disulfonated poly(arylene ether sulfone) and hydrophobic partially fluorinated poly(arylene ether ketone) for fuel cell applications
Authors: Lee Hae‐Seung , Roy Abhishek , Lane Ozma , Lee Myoungbae , McGrath James E.
Published: November 2009

Sulfonated fluorinated multiblock copolymers based on high performance polymers were synthesized and evaluated for use as proton exchange membranes (PEMs). The multiblock copolymers consist of fully disulfonated poly(arylene ether sulfone) and partially fluorinated poly(arylene ether ketone) as hydrophilic and hydrophobic segments, respectively. Synthesis of the multiblock copolymers was achieved by a condensation coupling reaction between controlled molecular weight hydrophilic and hydrophobic oligomers. The coupling reaction could be conducted at relatively low temperatures (e.g., 105 °C) by utilizing highly reactive hexafluorobenzene (HFB) as a linkage group. The low coupling reaction temperature could prevent a possible trans‐etherification, which can randomize the hydrophilic‐hydrophobic sequences. Tough ductile membranes were prepared by solution casting and their membrane properties were evaluated. With similar ion exchange capacities (IECs), proton conductivity and water uptake were strongly influenced by the hydrophilic and hydrophobic block sequence lengths. Conductivity and water uptake increased with increasing block length by developing nanophase separated morphologies. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) experiments revealed that the connectivity of the hydrophilic segments was enhanced by increasing the block length. The systematic synthesis and characterization of the copolymers are reported. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 214–222, 2010
Investigation by combined solid‐state NMR and SAXS methods of the morphology and domain size in polystyrene‐b‐polyethylene oxide‐b‐polystyrene triblock copolymers
Authors: Bonk Fábio A. , Caldarelli Stefano , Phan Trang , Bertin Denis , Deazevedo Eduardo R. , Mantovani Gerson Luiz , Bonagamba Tito J. , Plivelic Tomás S. , Torriani Iris L.
Published: November 2009

The microphase structure of a series of polystyrene‐b‐polyethylene oxide‐b‐polystyrene (SEOS) triblock copolymers with different compositions and molecular weights has been studied by solid‐state NMR, DSC, wide and small angle X‐ray scattering (WAXS and SAXS). WAXS and DSC measurements were used to detect the presence of crystalline domains of polyethylene‐oxide (PEO) blocks at room temperature as a function of the copolymer chemical composition. Furthermore, DSC experiments allowed the determination of the melting temperatures of the crystalline part of the PEO blocks. SAXS measurements, performed above and below the melting temperature of the PEO blocks, revealed the formation of periodic structures, but the absence or the weakness of high order reflections peaks did not allow a clear assessment of the morphological structure of the copolymers. This information was inferred by combining the results obtained by SAXS and1H NMR spin diffusion experiments, which also provided an estimation of the size of the dispersed phases of the nanostructured copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 55–64, 2010
Low dose, alternating electric current inhibits growth of prostate cancer
Authors: Koreckij Theodore D. , Hill Charles , Azure Larry , Nguyen Holly , Kunz Lawrence L. , Azure Andrew , Corey Eva , Lange Paul , Vessella Robert L.
Published: November 2009

BACKGROUND

A number of minimally invasive technologies exist for the treatment of prostate cancer (CaP), each with their associated morbidities. We sought to test the efficacy of low dose alternating electric current (LDAEC) to inhibit CaP growth in a preclinical setting and determine its effect on normal tissue.

METHODS

In the first study, two power settings, 15 or 25 mA of current, and two treatment times, 15 or 60 min, were evaluated in C4‐2B CaP xenografts. In the second study, power was regulated to maintain an intra‐tumoral temperature of ≤45°C in C4‐2B and LuCaP 35 tumors. In both studies, tumor volume, serum PSA levels, survival and histology were analyzed. In a third study, LDAEC was applied to mice hamstrings with evaluation of gait and histology.

RESULTS

The most effective tumor volume reduction in the first study was seen with tumors treated with 25 mA for 15 min (62 ± 9.4% decrease, P = 0.001). Longer treatment time did not enhance treatment effect. Using 45°C to govern delivery of LDAEC resulted in a near 100% reduction in tumor volume in 8/10 mice with C4‐2B tumors (P < 0.001) with similar inhibition of LuCaP 35 tumors (P = 0.01). This treatment, although resulting in skeletal muscle necrosis, did not affect nerves, smooth muscle and blood vessels.

CONCLUSION

LDAEC demonstrates efficacy against C4‐2B and LuCaP 35 CaP xenografts while causing no harm to nerves and blood vessels. These results warrant further investigations into the use of LDAEC as a treatment for CaP. Prostate 70: 529–539, 2010. © 2009 Wiley‐Liss, Inc.
FREAD revisited: Accurate loop structure prediction using a database search algorithm
Authors: Choi Yoonjoo , Deane Charlotte M.
Published: November 2009

Loops are the most variable regions of protein structure and are, in general, the least accurately predicted. Their prediction has been approached in two ways, ab initio and database search. In recent years, it has been thought that ab initio methods are more powerful. In light of the continued rapid expansion in the number of known protein structures, we have re‐evaluated FREAD, a database search method and demonstrate that the power of database search methods may have been underestimated. We found that sequence similarity as quantified by environment specific substitution scores can be used to significantly improve prediction. In fact, FREAD performs appreciably better for an identifiable subset of loops (two thirds of shorter loops and half of the longer loops tested) than the ab initio methods of MODELLER, PLOP, and RAPPER. Within this subset, FREAD's predictive ability is length independent, in general, producing results within 2Å RMSD, compared to an average of over 10Å for loop length 20 for any of the other tested methods. We also benchmarked the prediction protocols on a set of 212 loops from the model structures in CASP 7 and 8. An extended version of FREAD is able to make predictions for 127 of these, it gives the best prediction of the methods tested in 61 of these cases. In examining FREAD's ability to predict in the model environment, we found that whole structure quality did not affect the quality of loop predictions. Proteins 2010. © 2009 Wiley‐Liss, Inc.
Crystal structure of the MukB hinge domain with coiled‐coil stretches and its functional implications
Authors: Ku Bonsu , Lim Jae‐Hong , Shin Ho‐Chul , Shin Seong‐Yeol , Oh Byung‐Ha
Published: November 2009

The structural maintenance of chromosomes (SMC) family proteins are commonly found in the multiprotein complexes involved in chromosome organization, including chromosome condensation and sister chromatid cohesion. These proteins are characterized by forming a V‐shaped homo‐ or heterodimeric structure with two long coiled‐coil arms having two ATPase head domains at the distal ends. The hinge domain, located in the middle of the coiled coil, forms the dimer interface. In addition to being the dimerization module, SMC hinges appear to play other roles, including the gateway function for DNA entry into the cohesin complex. Herein, we report the homodimeric structure of the hinge domain of Escherichia coli MukB, which forms a prokaryotic condensin complex with two non‐SMC subunits, MukE and MukF. In contrast with SMC hinge of Thermotoga maritima which has a sizable central hole at the dimer interface, MukB hinge forms a constricted dimer interface lacking a hole. Under our assay conditions, MukB hinge does not interact with DNA in accordance with the absence of a notable positively charged surface patch. The function of MukB hinge appears to be limited to dimerization of two copies of MukB molecules. Proteins 2010. © 2009 Wiley‐Liss, Inc.
Cross‐resistance study and biochemical mechanisms of thiamethoxam resistance in B‐biotype Bemisia tabaci (Hemiptera: Aleyrodidae)
Authors: Feng Yuntao , Wu Qingjun , Wang Shaoli , Chang Xiaoli , Xie Wen , Xu Baoyun , Zhang Youjun
Published: November 2009

BACKGROUND: B‐biotype Bemisia tabaci (Gennadius) has invaded China over the past two decades. To understand the risks and to determine possible mechanisms of resistance to thiamethoxam in B. tabaci, a resistant strain was selected in the laboratory. Cross‐resistance and the biochemical mechanisms of thiamethoxam resistance were investigated in the present study.

RESULTS: A 66.3‐fold thiamethoxam‐resistant B. tabaci strain (TH‐R) was established after selection for 36 generations. Compared with the susceptible strain (TH‐S), the selected TH‐R strain showed obvious cross‐resistance to imidacloprid (47.3‐fold), acetamiprid (35.8‐fold), nitenpyram (9.99‐fold), abamectin (5.33‐fold) and carbosulfan (4.43‐fold). No cross‐resistance to fipronil, chlorpyrifos or deltamethrin was seen. Piperonyl butoxide (PBO) and triphenyl phosphate (TPP) exhibited significant synergism on thiamethoxam effects in the TH‐R strain (3.14‐ and 2.37‐fold respectively). However, diethyl maleate (DEM) did not act synergistically with thiamethoxam. Biochemical assays showed that cytochrome P450 monooxygenase activities increased 1.21‐ and 1.68‐fold respectively, and carboxylesterase activity increased 2.96‐fold in the TH‐R strain. However, no difference was observed for glutathione S‐transferase between the two strains.

CONCLUSION: B‐biotype B. tabaci develops resistance to thiamethoxam. Cytochrome P450 monooxygenase and carboxylesterase appear to be responsible for the resistance. Reasonable resistance management that avoids the use of cross‐resistance insecticides may delay the development of resistance to thiamethoxam in this species. Copyright © 2009 Society of Chemical Industry
Effect of shell‐layer thickness on dielectric properties in Ag@TiO2 core@shell nanoparticles filled ferroelectric poly(vinylidene fluoride) composites
Authors: Dang Zhi‐Min , You Shi‐Shu , Zha Jun‐Wei , Song Hong‐Tao , Li Sheng‐Tao
Published: November 2009

The Ag@TiO2 core@shell nanoparticles filled ferroelectric poly(vinylidene fluoride) (PVDF)‐based composites (0–3 connectivity) were prepared in order to study the effect of core@shell structure on dielectric permittivity in the Ag@TiO2/PVDF nanocomposites. The Ag@TiO2 core@shell nanoparticles were synthesized via a water‐thermal meting route. Transmission electron microscope (TEM) images showed the nanoparticles were about 60–120 nm in diameter and the thickness of the shell layer was about 6–12 nm, which can be adjusted by changing the fabrication conditions. Results of dielectric measurements showed that the shell‐layer thickness of the Ag@TiO2 core@shell nanoparticles played a key role in deciding the final values of the dielectric properties of the nanocomposites. The variation of dielectric properties of the nanocomposites with temperature also depends on the shell‐layer thickness of the Ag@TiO2 core@shell nanoparticles.
A novel method to synthesize cobalt oxide (Co3O4) nanowires from cobalt (Co) nanobowls
Authors: Srivastava A. K. , Madhavi S. , Ramanujan R. V.
Published: November 2009

A novel method suitable for the synthesis of the cobalt oxide (Co3O4) nanowires at targeted regions is presented in this report. Cobalt (Co) nanobowls synthesized by colloidal crystal directed assembly were transformed into Co3O4 nanowires by a simple heat treatment process. Co nanobowls exhibited a two phase (h.c.p. + f.c.c.) microstructure while single phase microstructure was observed for Co3O4 nanowires. Ferromagnetic Co nanobowls showed a dependence of coercivity on bowl size while Co3O4 exhibited weak ferromagnetic behavior.
Preparation and characterization of SU8–carbon nanotube composites
Authors: Mionić Marijana , Jiguet Sébastien , Judelewicz Moshe , Forró László , Magrez Arnaud
Published: November 2009

SU8–carbon nanotube composites have been produced to enhance the mechanical, electrical, and thermal properties of SU8 photoresists. Homogeneous composites materials have been obtained when multiwalled carbon nanotubes (MWCNTs) functionalized with COOH groups were used. Indeed, COOH groups can react with the epoxy ring of the SU8 molecule yielding an improved interaction between carbon nanotubes (CNTs) and the polymer matrix. Impedance spectroscopy was used to study the conducting percolation path in the composites, that is the quality of the nanotube dispersion in the epoxy matrix. It turns out that propylene glycol methyl ether acetate (PGMEA) as well as gamma‐butyrolacton (GBL) are very suitable solvent to prepare SU8‐MWCNTs composites of good homogeneity.
Optical characterisation of aluminium nitride as antireflective coating by a new remote plasma deposition system
Authors: Claudio G. , Kaminski P. , Bass K.
Published: November 2009

High bandgap materials have recently attract a lot of interest for their potential application in photovoltaics (PV). Aluminium nitride (AlN)) is a potential candidate for passivation and antireflective coating in silicon solar cells. AlN thin films have been deposited by a new remote plasma deposition system HiTUS (High Target Utilisation Sputtering). The AlN thin films are grown by reactive sputtering from an aluminium target in an N2 atmosphere, negating the use of silane gas commonly used in PECVD method. PC1D simulations have been performed to calculate the best thickness for antireflection and passivation of silicon wafers. Several depositions have been performed at different substrate temperatures. Photoconductive measurements by a WCT‐100 were performed on silicon wafer after each thermal process to measure the effective lifetime of p‐type crystalline silicon wafer boron doped <100> to measure the effective lifetime of the minority carriers. Reflectance and transmission measurements were performed for sample at different bias and flow gas ratio. Results shows that a complete transmission with a reflection of less than 5% occurs for samples with a thickness of 50 nm. An increase in carrier lifetime has been observed for AlN deposited at high temperature. Lifetime has increased in wafer annealed at 300 °C up to 15 μs suggesting the potential of AlN for silicon passivation and an alternative antireflective coating to silicon nitride. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tunneling current in gate dielectric stack in sub‐45 nanometer CMOS devices
Authors: Tyagi Hitender Kumar , Prasad B. , George P. J.
Published: November 2009

Direct tunneling current through dual layer SiO2/high‐K dielectric structures are investigated for substrate injection. Correlation of dielectric constants and band offsets with respect to silicon has been taken into consideration in order to identify possible materials to construct these devices. The direct tunneling current in oxide/high‐K dielectric structures with equivalent oxide thickness (EOT) of 2.0 nm can be significantly lower than that through single layer oxides of the same thickness. Various structures and materials of high‐K stacks of interest have been examined and compared to access the reduction of gate current in these structures. It is estimated that HfO2/SiO2 dual stack structure can reduce gate leakage current by four orders of magnitude as compared with pure SiO2 layer of same EOT. The importance of interfacial layer in dual stack structure is high‐lighted for the reduction of gate leakage current. The present approach is capable of modeling high‐K stack structures consisting of multiple layers of different dielectrics (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Boron‐ and stoichiometry‐related defect engineering during B2O3‐free GaAs crystal growth
Authors: Kiessling F.‐M. , Albrecht M. , Irmscher K. , Roßberg M. , Rudolph P. , Ulrici W. , Fornari R.
Published: November 2009

GaAs crystals have been grown without B2O3 encapsulation by the vapour‐pressure controlled Czochralski (VCz) method to reduce undesired boron incorporation and to enable in situ control of the Ga/As ratio in the melt. With increasing Ga content of the melt the omnipresent As precipitate concentration decreases in as‐grown GaAs crystals. Semiinsulating (SI) GaAs crystals could been obtained even from melts with a composition of 46 at.% As. Comparative cathodoluminescence (CL) measurements on those crystals and on boron‐contaminated GaAs show that the luminescence bands at 1.316 eV and at 1.441 eV are related to BAs. Reduced concentrations of boron and EL2 result in significant lower near‐band edge absorption, mainly caused by the photoionization cross section of As antisites in SI GaAs. These VCz GaAs crystals possess improved optical properties. Semi‐conducting (SC) GaAs:Si crystals were grown from near‐stoichiometric melts. Positron annihilation lifetime spectroscopy measurements show that the low boron concentration in our SC VCz GaAs results always in 3 times higher Ga vacancy concentrations compared to standard SC GaAs. CL bands due to optical transitions at 0.95 eV and 1.15 eV are related to auto‐compensating (VGaSiGa)2‐ and (SiGaVGaSiGa)– complexes, respectively, and depend on the doping level. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nature of vacancy defect clusters in chalcogenic semiconductors of AIIBVI group irradiated by neutrons
Authors: Davidyuk G. Y. , Bozhko V. V. , Myronchuk G. L. , Kevchin A. G. , Kažukauskas V.
Published: November 2009

An experimentally proven model is proposed stating that vacancies of cadmium atoms are dominating in kernels of the defect clusters (DCs) formed in single CdS crystals by the irradiation with fast 1 MeV reactor neutrons. The so‐called subthreshold effects play the essential role in cluster formation. The subthreshold effects consequently lead to the excitation and ionization of the K‐shell of Cd atoms followed by an increase of charge of Cd ions. This finally result in an ejection of these ions from the kernels to periphery of DCs due to the electrostatic force (electrostatic explosion). (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Charge spectroscopy of Si nanocrystals in a SiO2 matrix
Authors: Antonova Irina , Neustroev Efim , Smagulova Svetlana , Jedrzejewski Jedrzej
Published: November 2009

For the first time, the recharging of semiconductor nanocrystals (NCs) embedded in a dielectric matrix was studied by means of charge deep‐level transient spectroscopy (Q‐DLTS). Our measured Q‐DLTS spectra were found to arise from two or three transient processes with different activation energies observed in different temperature ranges. We suggest that these are associated with quantum‐confined electronic states in Si NCs. The data obtained were used to extract the energy position of NC levels, the size of NCs, and the typical recharging times of weakly coupled NCs. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermo‐optical investigations of NaNbO3 thin films by spectral ellipsometry
Authors: Aulika Ilze , Dejneka Alexandr , Lynnyk Anna , Zauls Vismants , Kundzins Maris
Published: November 2009

In this work a spectroscopic ellipsometry was applied to the thermo‐optical investigations of sodium niobate NaNbO3 (NN) thin films at the wide temperature range of 5–820 K. The temperature dependence of complex refractive index dispersions and optical bang energy of the direct allowed electron transitions were evaluated. Additionally dynamic scans of the main ellipsometric angles at the several fixed wave lengths of 300, 400, 500 and 635 nm were performed to acquire more detailed temperature dependences of the refractive index and extinction coefficient. Pronounced minima/maxima and substantial jumps in the temperature dependence of complex refractive index and band gap energy were found and corresponded to the structural phase transition temperatures of NN single crystals and ceramics. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
QSPR Study on the Melting Points of a Diverse Set of Potential Ionic Liquids by Projection Pursuit Regression
Authors: Ren Yueying , Qin Jin , Liu Huanxiang , Yao Xiaojun , Liu Mancang
Published: November 2009

A Quantitative Structure–Property Relationship (QSPR) study was carried out to model the melting points for a diverse set of 288 potential Ionic Liquids (ILs) including pyridinium bromides, imidazolium bromides, benzimidazolium bromides, and 1‐substituted 4‐amino‐1,2,4‐triazolium bromides. Based on the calculated descriptors by CODESSA program, a Principal Component Analysis (PCA) was performed on the whole data to detect the homogeneities in the dataset and to assist the separation of the data into representative training and test sets. Heuristic Method (HM) and Projection Pursuit Regression (PPR) were used to develop linear and nonlinear models between the descriptors and the melting points. The PPR model gave a high predictive correlation coefficient (R2) of 0.810 and an Average of Absolute Relative Deviation (AARD) of 17.75%, which are better than those by HM model (R2=0.712, AARD=24.33%) indicating that PPR is better for the prediction of the melting points. In addition, the descriptors selected by HM can give some insight into factors that can affect the melting points, i.e., benzene ring structure, rotatable bonds, branching, symmetry, and intramolecular electronic effects. This information would be very useful in the design of the potential ILs with desired melting points.
Hybrid single frequency network propagation channel sounding and antenna diversity measurements
Authors: Lacoste Frédéric , Scot Gaël , Ros Benjamin , Pajusco Patrice , Conrat Jean Marc , Perez Fontan Fernando
Published: November 2009

During the last decade, several land mobile communication networks have been developed based on full satellite solutions such as Globalstar or Iridium systems or on huge terrestrial networks such as GSM for example. Deploying new terrestrial networks or new satellite constellations for new telecommunication or broadcast mobile systems on very large areas would be so expensive that another solution is now often considered: hybrid systems with a terrestrial segment to cover high‐density built‐up areas and a satellite segment to bring services to the largest part of coverage area. In the framework of Satellite Digital Multimedia Broadcasting CNES project, such a hybrid mobile broadcast system was studied, in particular air interface performances. This performance assessment required a good knowledge of the hybrid single frequency network (SFN) propagation channel including a geostationary satellite and terrestrial gap fillers. The requirement for an exhaustive characterization of the hybrid SFN propagation channel involved the development of a specific channel sounding solution. Moreover, mobile telecommunication systems recently developed use spatial diversity techniques to take benefit from multipath spatial decorrelation in particular. The measurement of diversity gains in actual conditions can provide information very helpful for network deployment and air interface design. The CNES channel sounder enables to carry out such diversity measurements using only propagation data. This paper presents this channel sounder developed and used to measure the SFN radio propagation channel with four transmitters in spatial diversity configuration. Copyright © 2009 John Wiley & Sons, Ltd.
Phosphorylation of Corn Starch in an Ionic Liquid
Authors: Xie Wenlei , Shao Li
Published: November 2009

Corn starch was phosphorylated by reaction with sodium dihydrogenphosphate or disodium hydrogenphosphate using 1‐butyl‐3‐methylimidazolium chloride (BMIMCl) as reaction medium. The parameters varied included the molar ratio of reactant, reaction time and temperature and were investigated regarding the degree of substitution for the phosphorylated starch. The degree of substitution of starch phosphates prepared ranged from 0.03 to 0.55. The product was characterized by Fourier‐transform infrared (FT‐IR) spectroscopy, scanning electron microscopy (SEM) and X‐ray diffraction (XRD) techniques. It was found that the native crystallinity of corn starch was largely distroyed during the dissolution and functionalization process in the ionic liquid system under the reaction conditions.
Characterization of the Pasting, Flow and Rheological Properties of Native and Phosphorylated Rice Starches
Authors: Lin Qinlu , Xiao Huaxi , Zhao Jian , Li Lihui , Yu Fengxiang
Published: November 2009

Phosphorylation of rice starch and its effects on the physiochemical properties of the starch were investigated. Phosphorylation was conducted using the oven heating method by heating mixtures of rice starch and monosodium dihydrogenphosphate at 120‐150°C for 0.5‐2 h, and the pasting, flow and rheological properties of the resulting starch phosphates were analyzed. Phosphorylation with substitution degrees of up to 0.12 was achieved by raising the reaction temperature to 140°C, but further increase in the temperature to 150°C caused a marked reduction in the degree of substitution. Phosphorylation resulted in significant declines in pasting temperature and setback, but increases in peak viscosity and breakdown. Suspensions of rice native starch and starch phosphates were shown to be non‐Newtonian, pseudoplastic fluids, exhibiting typical shear thinning. They also exhibited yield stress, the magnitude of which increased with the degree of phosphate substitution. Dynamic testing showed that phosphorylation resulted in a decrease in the temperature at which storage and loss moduli (G′ and G″) reached a peak during heating and a reduction in G′ during cooling. These results appeared to indicate that phosphorylation improved the shear stability of rice starch pastes and enhanced swelling of starch granules, but impeded starch retrogradation.
α‐methylene‐γ‐butyrolactones: versatile skin bioactive natural products
Authors: Lepoittevin Jean‐Pierre , Berl Valérie , Giménez‐Arnau Elena
Published: November 2009

Natural products containing an α‐methylene‐γ‐butyrolactone moiety, mainly of the sesquiterpene type, are widely observed in plants, which upon coming into contact with skin, will induce major skin toxicological side effects or phytodermatitis. Indeed two main dermatological pathologies have been associated with a skin exposure to molecules containing an α‐methylene‐γ‐butyrolactone moiety: allergic contact dermatitis (ACD) and chronic actinic dermatitis (CAD). ACD is an immunologically based disease resulting from modifications of epidermal proteins by sensitizers or haptens. Indeed, α‐methylene‐γ‐butyrolactones are highly electrophilic structures that can act as Michael acceptors towards nucleophilic residues of proteins. Cysteine and lysine are the most modified residues leading, in the case of enantiomerically pure lactones, to the formation of diastereomeric adducts. This chemical enantioselectivity induces an enantiospecificity of the allergic reaction, i.e., an individual sensitized to one enantiomer will not develop clinical symptoms when exposed to the other enantiomer and vice versa. Sesquiterpene lactones have been also associated with another pathology that involves UV irradiation and DNA modifications. Interestingly, it was found that α‐methylene‐γ‐butyrolactones, in addition to their electrophilic properties, were highly photoreactive molecules able to react with thymine/thymidine to form [2 + 2] photoadducts in very high yields. In all cases a syn regioselectivity was observed, probably associated with the polarization of the exomethylenic bond. This high photoreactivity of α‐methylene‐γ‐butyrolactones towards thymidine could be an explanation of the progressive evolution of allergic contact dermatitis towards chronic actinic dermatitis. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 000–000; 2009: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.200900013
Mirror symmetry breaking of silicon polymers—from weak bosons to artificial helix
Authors: Fujiki Michiya
Published: November 2009

From elemental particles to human beings, matter and living worlds in our universe are dissymmetric with respect to mirror symmetry. Since the early 19th century, the origin of biomolecular handedness has been puzzling scientists. Nature's elegant bottom‐up preference, however, sheds light on new concepts of generating, amplifying, and switching artificial polymers, supramolecules, liquid crystals, and organic crystals that can exhibit ambidextrous circular dichroism in the UV/Visible region with efficiency in production under milder ambient conditions. In the 1920s, Kipping, who first synthesized polysilanes with phenyl groups, had much interest in the handedness of inorganic and organic substances from 1898 to 1909 in his early research life. Polysilanes—which are soluble Si‐Si bonded chain‐like near‐UV chromophores that carry a rich variety of organic groups—may become a bridge between animate and inanimate polymer systems. The present account focuses on several mirror symmetry breaking phenomena exemplified in polysilanes carrying chiral and/or achiral side groups, which are in isotropic dilute solution, as polymer particles dispersed in solution, and in a double layer film immobilized at the solid surface, and subtle differences in the helix, by dictating ultimately ultraweak chiral forces at subatomic, atomic, and molecular levels. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 000–000; 2009: Published online in Wiley InterScience (www.interscience.wiley.com)DOI 10.1002/tcr.200900018
Atypical presentation of ruptured ectopic pregnancy
Authors: Maharajan Pushpakala Ajaya , Minas Vasileios , Gupta Nandini
Published: November 2009

The authors present a case history of a woman with vaginal bleeding who was found to have a ruptured ectopic pregnancy, initially misdiagnosed as an incomplete miscarriage. Doctors need to have a high suspicion of ectopic pregnancy in early diagnosis and interventions. Copyright © 2009 Wiley Interface Ltd
Transient chaotic behaviour versus periodic motion of a parametric pendulum by recurrence plots
Authors: Litak G. , Wiercigroch M. , Horton B.W. , Xu X.
Published: November 2009

We investigated dynamic responses of a parametric pendulum obtained experimentally. Using the recurrence plot technique designed to analyze experimental time series we have distinguished different types of motion. This method, supplemented by recurrence quantification analysis (RQA), has been used to identify oscillations, rotations, and transient chaotic vibrations for relatively short time series composed of only few cycles.
Effects of finite dimension on the electro‐elastic responses of an interface electrode in a piezoelectric actuator
Authors: Li Y.‐D. , Lee K.Y.
Published: November 2009

All piezoelectric actuators are of finite dimension. The effect of finite geometry on the electro‐elastic responses is of significance to the design of practical actuators. Electromechanical model is established for an interface electrode in a piezoelectric actuator with finite dimension. The methods of infinite series and Cauchy singular integral equation are employed to perform the electro‐elastic analysis. The accuracy of numerical calculation is analyzed and the suitability of the present methods is discussed. Parametric studies on the electro‐elastic intensity factors yield three conclusions. (a) A central electrode rather than an off‐center one can help to enhance the structural reliability. (b) For an actuator with central electrode, it is better to make the interface twice as long as the electrode. For an actuator with periodical interface electrodes, the optimal allocation of electrodes is to make the space identical to the electrode length. (c) The thickness of the piezoelectric layer should be at least a quarter of the electrode length.
A data-flow approach to test multi-agent ASMs
Authors: Cavarra Alessandra
Published: November 2009

This paper illustrates the theoretical basis of an approach to apply data flow testing techniques to abstract state machines (ASMs). In particular, we focus on multi-agent ASMs extended with theseqconstruct for turbo ASMs. We explain why traditional data flow analysis can not simply be applied to ASMs: data flow coverage criteria are strictly based on the mapping between a program and its flow graph whereas in this context we are interested in tracing the flow of data between states in ASM runs as opposed to between nodes in a program’s flow graph. We revise the classical concepts in data flow analysis taking into account the specific, parallel nature of ASMs, and define them on two levels: the syntactic (rule) level, and the computational (run) level. In particular, we analyze the role played by different types of terms in ASMs and deal with the problem of terms that are monitored by a given agent but controlled by another one, terms that are shared between several agents, and derived terms. We also discuss what consequences the use of the turbo ASM constructseqhas on our analysis and revise the approach accordingly. Finally, we specify a family of ad hoc data flow coverage criteria for this class of ASMs and introduce a model checking-based approach to generate automatically test cases satisfying a given set of coverage criteria from ASM models.
HOCl‐Mediated Glycerophosphocholine and Glycerophosphoethanolamine Generation from Plasmalogens in Phospholipid Mixtures
Authors: Leßig Jacqueline , Fuchs Beate
Published: November 2009

Many mammalian tissues and cells contain, in addition to (diacyl) phospholipids, considerable amounts of plasmalogens, which may function as important antioxidants. Apart from the “scavenger” function mediated by the high sensitivity of the vinyl‐ether bond, the functional role of plasmalogens is so far widely unknown. Furthermore, there is increasing evidence that plasmalogen degradation products have harmful effects in inflammatory processes. In a previous investigation glycerophosphocholine (GPC) formation was verified as a novel plasmalogen degradation pathway upon oxidation with hypochlorous acid (HOCl), however these investigations were performed in simple model systems. Herein, we examine plasmalogen degradation in a more complex system in order to evaluate if GPC generation is also a major pathway in the presence of other highly unsaturated glycerophospholipids (GPL) representing an additional reaction site of HOCl targets. Using MALDI–TOF mass spectrometry and 31P NMR spectroscopy, we confirmed that the first step of the HOCl‐induced degradation of GPL mixtures containing plasmalogens is the attack of the vinyl‐ether bond resulting in the generation of 1‐lysophosphatidylcholine (lysoPtdCho) or 1‐lysophosphatidylethanolamine. In the second step HOCl reacts with the fatty acyl residue in the sn‐2 position of 1‐lysoPtdCho. This reaction is about three times faster in comparison to comparable diacyl‐GPL. Thus, the generation of GPC and glycerophosphoethanolamine (GPE) from plasmalogens are relevant products formed from HOCl attack on the vinyl‐ether bond of plasmalogens under pathological conditions.
Klinik und Genetik der Neurofibromatose Typ 1
Authors: Kehrer-Sawatzki H. , Mautner V.-F.
Published: November 2009

Die Neurofibromatose Typ 1 (NF1) ist eine autosomal-dominant vererbte Erkrankung. Sie wird durch Mutationen imNF1-Gen auf Chromosom 17q11.2 verursacht. Sie zeigt volle Penetranz, d. h. jeder, der eine Mutation trägt, weist Merkmale der Krankheit auf, jedoch mit z. T. erheblich variabler Expressivität. NF1 ist gekennzeichnet durch die namensgebenden Neurofibrome, bei welchen es sich um gutartige Tumoren der Nervenscheiden handelt. Zu den häufig primär auftretenden Symptomen zählen Pigmentierungsanomalien der Haut, wie Café-au-Lait-Flecken, axilläres bzw. inguinales Freckling, sowie Lisch-Knötchen der Iris. NF1 gehört zur Gruppe der hereditären Tumorerkrankungen. Betroffene weisen ein erhöhtes Risiko auf, an bestimmten NF1-assoziierten Tumoren zu erkranken, die durch eine biallelische Inaktivierung desNF1-Tumorsuppressorgens und aberrante RAS-Signaltransduktion entstehen. In den letzten Jahren sind signifikante Fortschritte bei der Identifizierung und Behandlung der NF1-assoziierten klinischen Symptome sowie in der Entwicklung neuer Therapieansätze zu verzeichnen.