bluuebunny/crossref_metadata_2025 huggingface dataset:
New poly(phenylenevinylene)‐methyl methacrylate‐based photonic crystals
Authors: Achelle Sylvain , Blanco Álvaro , López‐García Martín , Sapienza Riccardo , Ibisate Marta , López Cefe , Rodríguez‐López Julián
Published: May 2010

Monodisperse colloids have been prepared efficiently by copolymerization of methyl methacrylate and fluorescent first‐ and second‐generation poly(phenylenevinylene) dendrons under surfactant‐free emulsion polymerization conditions. The copolymers were characterized by UV–vis and fluorescence spectroscopy and size exclusion chromatography. Transmission electron microscopy revealed that the copolymers were microspheres with smooth surfaces and narrow dispersity. The bead diameter could be varied by changing the monomer/water ratio. The materials could be crystallized to give polymer opal photonic crystals. The emission was not affected by the periodic structure because of the large spectral distance between the emission and the pseudogap position. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2659–2665, 2010
Unexpected alternating radical copolymerization of chlorotrifluoroethylene with 3‐isopropenyl‐α,α′‐dimethylbenzyl isocyanate
Authors: Kyulavska M. , Kostov G. , Ameduri B. , Mateva R.
Published: May 2010

The radical solution copolymerization of hexafluoropropylene, chlorotrifluoroethylene (CTFE), vinylidene fluoride, and tert‐butyl‐α‐trifluoromethylacrylate with different monomers bearing isocyanato groups such as allyl isocyanate, 3‐isopropenyl‐α,α′‐dimethylbenzyl isocyanate (m‐TMI), and 2‐isocyanatoethyl methacrylate, initiated by 2,5‐bis(tert‐butylperoxy)‐2,5‐dimethylhexane were studied. Several of these radical copolymerizations were not successful in contrast to that of CTFE with m‐TMI, although m‐TMI monomer does not homopolymerize under radical initiation. The resulting poly(CTFE‐co‐m‐TMI) copolymers were characterized by 1H and 19F nuclear magnetic resonance and Fourier transform infrared spectroscopy and their compositions assessed by elemental analysis. The reactivity ratios of both comonomers were determined by linearization methods of Fineman‐Ross, Kelen‐Tüdös for low conversions of monomers, and by the extended Kelen‐Tüdös method for high monomer conversions. The average values of the monomer reactivity ratios, rCTFE and rm‐TMI, were 0.076 and 0.034 at 130 °C, respectively, depending on these monomer conversions and the applied methods of calculation. In all cases, rCTFE × rm‐TMI product was close to zero, which indicates that poly(CTFE‐co‐m‐TMI) copolymers exhibit a high tendency toward alternation. This was also confirmed by the Igarashi's theory which revealed a high content of CTFE‐m‐MTI heterodyads. The Q and e values for m‐TMI monomer were also assessed (Qm‐TMI = 0.007 and em‐TMI = 0.99). As well as this kinetics of copolymerization, several properties of the obtained fluorofunctional copolymers such as molecular weights (ranging from 1500 to 8200 g mol−1), molecular weight distributions (from 1.2 to 2.1) were also investigated. Their thermal properties revealed satisfactory thermal stability (higher than 250 °C). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2681–2697, 2010
Nonlinear stress relaxation of carbon black‐filled rubber vulcanizates under various types of deformation
Authors: Tada Toshio , Urayama Kenji , Mabuchi Takahiro , Muraoka Kiyoshige , Takigawa Toshikazu
Published: May 2010

Nonlinear stress relaxation behavior of carbon black‐filled rubber vulcanizates under large strain is investigated for the three types of deformation (equibiaxial stretching, pure shear, and uniaxial stretching) with various sets of two principal ratio (λ1 and λ2). The stress relaxation curves in the wide time (t) region of t > 10−1 s at a reference temperature of 296 K are obtained by the time‐temperature superposition principle. We demonstrate that stress relaxation component Δσ(λ1, λ2, t) (≡ σ[λ1, λ2, t] − σ[λ1, λ2, ∞], where σ[λ1, λ2, ∞] is the equilibrium stress) is separable into the time (t)‐ and deformation (λ)‐dependent functions, that is, Δσ(λ1, λ2, t) = Δσtotal(λ1, λ2)ψ(t), where Δσtotal represents the total relaxation strength. We further show that the time‐dependent term ψ(t) of the filled rubbers is almost similar to that of the unfilled rubbers in the time region examined here, whereas Δσtotal for filled rubbers is considerably larger than that for unfilled ones. In addition, the reduced relaxation strength Δσtotal(λ1, λ2)/σ(λ1, λ2, ∞) is almost independent of the degree and type of deformation, and the value for the filled rubber is larger than that for the unfilled one. These results indicate that (1) the strain‐driven collapse of filler networks causes a large degree of stress relaxation, but it does not affect the relaxation dynamics in the time region investigated (∞ > t > 10−1 s), and (2) the relaxation dynamics in filled rubbers is governed by that in the rubber matrix. These findings considerably facilitate the full description of the finite deformation with time effect for filled rubbers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1380–1387, 2010
Scaling of the molecular weight‐dependent thermal volume transition of poly(N‐isopropylacrylamide)
Authors: Ye Xiaodong , Ding Yanwei , Li Junfang
Published: May 2010

A series of narrowly distributed poly(N‐isopropylacrylamide) (PNIPAM) with molecular weight ranging from 8 × 104 to 2.3 × 107 g/mol were prepared by a combination of free radical polymerization and fractional precipitation. An ultrasensitive differential scanning calorimetry was used to study the effect of molecular weight on the thermal volume transition of these PNIPAM samples. The specific heat peak of the transition temperature (Tp,0) was obtained by extrapolation to zero heating rate (HR) because of the linear dependence of the transition temperature (Tp) on the HR. The relation between Tp,0 and the degree of polymerization (N) was investigated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1388–1393, 2010
Molecular composites composed of castor oil‐modified poly(ε‐caprolactone) and self‐assembled hydroxystearic acid fibers
Authors: Shibata Mitsuhiro , Teramoto Naozumi , Kaneko Katsuyuki
Published: May 2010

After (R)‐12‐hydroxystearic acid (HSA) was mixed at 100 °C with the castor oil‐modified poly(ε‐caprolactone) (CO‐PCL) prepared by the ring‐opening polymerization of ε‐caprolactone in the presence of castor oil, the mixture was gradually cooled to room temperature to give a solidified CO‐PCL/HSA composite. The CO‐PCL/HSA sample showed an exothermic peak at around 67–71 °C which was lower than the melting point of HSA (76.8 °C), indicating the formation of mesogenic HSA aggregates. The rheological measurement of the CO‐PCL/HSA revealed the formation of HSA organogel at around 67–55 °C during the cooling process from the melt. Furthermore, the polarized and normal optical microscopic analyses of CO‐PCL/HSA on the cooling stage revealed that anisotropic fibrous materials are formed at around 60 °C and then the fibrous network propagated over the matrix polymer. The flexural modulus and storage modulus of the CO‐PCL/HSA composite increased with increasing HSA content. The CO‐PCL/HSA composite annealed at 60 °C for 2 h on the cooling process had a higher flexural and storage modulus than the sample without annealing. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1281–1289, 2010
Nonisothermal crystallization kinetics of biodegradable poly(butylene succinate‐co‐propylene succinate)s
Authors: Lu Shih‐Fu , Chen Ming , Shih You‐Cheng , Chen Chi He
Published: May 2010

Poly(butylene succinate) (PBSu) and two poly(butylene succinate‐co‐propylene succinate)s were synthesized via the direct polycondensation reaction. The copolyesters were characterized as having 7.0.and 11.5 mol % propylene succinate (PS) units, respectively, by 1H NMR. A differential scanning calorimeter (DSC) and a polarized light microscope (PLM) adopted to study the nonisothermal crystallization of these polyesters at a cooling rate of 1, 2, 3, 5, 6, and 10 °C/min. Morphology and the isothermal growth rates of spherulites under PLM experiments were monitored and obtained by curve‐fitting. These continuous rate data were analyzed with the Lauritzen−Hoffman equation. A transition of regime II → III was found at 95.6, 84.4, and 77.3 °C for PBSu, PBPSu 95/5, and PBPSu 90/10, respectively. DSC exothermic curves show that all of the nonisothermal crystallization occurred in regime III. DSC data were analyzed using modified Avrami, Ozawa, Mo, Friedman, and Vyazovkin equations. All the results of PLM and DSC measurements indicate that incorporation of minor PS units into PBSu markedly inhibits the crystallization of the resulting polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1299–1308, 2010
Role of temperature during ageing under gamma irradiation of filled EPDM: consequences on mechanical properties
Authors: Planes Emilie , Chazeau Laurent , Vigier Gérard
Published: May 2010

Filled EPDM materials have been processed and aged by gamma radiation at ambient temperature and at 80 °C to study the influence of the fillers presence in the material degradation. The acceleration of the polymer degradation by the ATH fillers, evidenced when irradiation is performed at 25 °C, is also effective at 80 °C. In addition, in the case of silica‐filled EPDM, the creation of strong filler‐matrix bonds, already reported for irradiation at 25 °C, is also thermally activated; this enables to this material to keep its integrity at high irradiation dose, whereas the irradiated ATH‐filled EPDM is so degraded that it flows. Thus, the introduction of fillers in the polymer has an impact on its resistance to irradiation, whatever the temperature at which the irradiation is performed. Moreover, the consequences of the degradation on the evolution of the mechanical properties of the composite are very dependent on the filler nature. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1319–1328, 2010
Synthesis and characterization of polypyrrole/graphite oxide composite by in situ emulsion polymerization
Authors: Gu Zheming , Li Chunzhong , Wang Gengchao , Zhang Ling , Li Xiaohui , Wang Wendong , Jin Shilei
Published: May 2010

This work demonstrates a feasible route to synthesize the layered polypyrrole/graphite oxide (PPy/GO) composite by in situ emulsion polymerization in the presence of cationic surfactant cetyltrimethylammonium bromide (CTAB) as emulsifier. AFM and XRD results reveal that the GO can be delaminated into nanosheets and well dispersed in aqueous solution in the presence of CTAB. The PPy nanowires are formed due to the presence of the lamellar mesostructured (CTA)2S2O8 as a template. The results of the PPy/GO composite indicate the PPy insert successfully into GO interlayers, and the nanofiber‐like PPy are deposited onto the GO surface. Owing to π–π electron stacking effect between the pyrrole ring of PPy and the unoxided domain of GO sheets, the electrical conductivity of PPy/GO composite (5 S/cm) significantly improves in comparison with pure PPy nanowires (0.94 S/cm) and pristine GO (1 × 10−6 S/cm). © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1329–1335, 2010
Linear viscoelastic characteristics of in situ compatiblized binary polymer blends with viscoelastic properties of components variable
Authors: Li Jingqing , Ma Guiqiu , Sheng Jing
Published: May 2010

By Friedel‐Crafts alkylation reaction, catalyzed by a Lewis acid of anhydrous aluminum chloride (AlCl3), binary polymer blends of polypropylene (PP)/polystyrene (PS) with volume proportion of 80/20 were in situ compatiblized and prepared in an XSS‐30 melt mixer at 210 °C. The linear viscoelastic characteristics of the blends were investigated by checking the variations of storage modulus, loss modulus, complex modulus, and complex viscosity of the in situ compatiblized blends, which were dependent on AlCl3 content. In addition, Han plots of the in situ compatiblized blends with different AlCl3 content were also used to characterize the linear viscoelastic properties of the blends. The results showed that both the dynamic rheological parameters and the Han plots were obviously influenced by the rheological properties of the matrix and slightly influenced by the rheological properties of the dispersed phase. Further investigations revealed that phase geometry contributions to the dynamic rheological parameters of the blends could be ignored in comparison with the contributions of the components and the interfacial modification, which were defined and obtained according to log‐linear‐additivity rule. The linear viscoelastic characteristics of the blends were mainly controlled by the combination of the effects of interfacial modification between phases and the rheological properties of the matrix. Storage modulus is the most sensitive dynamic rheological parameter to characterize the interfacial compatiblization effects in the in situ compatiblized binary polymer blends with rheological properties of components variable. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1349–1362, 2010
Evolutionary mechanism as a template for protein engineering
Authors: Eisenbeis Simone , Höcker Birte
Published: May 2010

The goal of a protein engineer is to adjust a protein to a specified new function. This is exactly what natural evolution has achieved many times. By studying evolutionary mechanisms, we can learn about ways to use the adaptability of proteins and to build new proteins. In fact, many techniques used in engineering are successfully mimicking evolutionary processes. We introduce the fundamental evolutionary mechanisms, take a closer look at duplication and fusion, recombination, and circular permutation and discuss their influence on protein engineering. Some important techniques are presented and illustrated with examples. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Phosphoramidate‐peptide synthesis by solution‐ and solid‐phase Staudinger‐phosphite reactions
Authors: Serwa Remigiusz A. , Swiecicki Jean‐Marie , Homann Denise , Hackenberger Christian P. R.
Published: May 2010

The chemoselective incorporation of phosphoramidate moieties into peptides by a Staudinger‐phosphite reaction of azides can be performed in many solvents, including water. In this report, we present two strategies for an efficient synthesis of phosphoramidate‐containing peptides, in which the Staudinger‐phosphite reaction is performed either on the solid support or in solution with aryl azido‐containing peptides. The corresponding Staudinger reactions proceed in high conversion rates and deliver phosphoramidate peptides, in which the modification site is located in the middle of the peptide sequence. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Structure–activity relationship of marinostatin, a serine protease inhibitor isolated from a marine organism
Authors: Taichi Misako , Yamazaki Tohimasa , Kawahara Kazuki , Motooka Daisuke , Nakamura Shota , Harada Shusaku , Teshima Tadashi , Ohkubo Tadayasu , Kobayashi Yuji , Nishiuchi Yuji
Published: May 2010

A 12‐residue MST isolated from a marine organism is a potent serine protease inhibitor that has a double cyclic structure composed of two ester linkages formed between the β‐hydroxyl and β‐carboxyl groups, Thr3‐Asp9and Ser8‐Asp11. MST was synthesized by a regioselective esterification procedure employing two sets of orthogonally removable side‐chain protecting groups for the Asp and Ser/Thr residues. In the MST molecule, there were no significant changes observed in yield by changing the order of esterification. SAR study of MST revealed that the minimum required structure for expressing the inhibitory activity is the sequence (1–9) in a monocyclic structure where Pro7located in the ring plays a crucial role in keeping the structural rigidity. By applying the structural motif of MST, we rationally designed protease inhibitory specificities that differ from those of the natural product. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
The effect of heat treatment on the phase constitution and magnetic properties of Pr9Fe60Co13Zr1Ti3B14 alloy ribbons
Authors: Pawlik Piotr , Pawlik Katarzyna , Davies Hywel A. , Wysłocki Jerzy J. , Gębara Piotr
Published: May 2010

Fully amorphous ribbon samples of the alloy Pr9Fe60Co13Zr1Ti3B14 were produced by the melt‐spinning technique under an Ar atmosphere. In the as‐cast state, the samples were soft magnetic, with a coercivity JHc of ∼10 A/m and saturation magnetization Jr of ∼1 T. Subsequent annealing at various temperatures Ta (from 903 to 973 K for 10 min) resulted in an evolution of the phase constitution together with a significant change of their magnetic properties. X‐ray diffractometry (XRD) revealed the presence of the hard magnetic Pr2(Fe,Co)14B phase, precipitated during annealing. However, quantitative analysis of Mössbauer spectra for the alloy showed a multiphase constitution with a relatively low volume fraction of this crystalline phase. Furthermore, the temperature dependences of magnetization confirmed differences in the constitution of the samples annealed at various temperatures. The aim of present work was to investigate the correlation between the phase constitution and magnetic properties of the ribbon samples.
Anomalous capacitance–voltage characteristics of Pt–AlGaN/GaN Schottky diodes exposed to hydrogen
Authors: Irokawa Yoshihiro , Matsuki Nobuyuki , Sumiya Masatomo , Sakuma Yoshiki , Sekiguchi Takashi , Chikyo Toyohiro , Sumida Yasunobu , Nakano Yoshitaka
Published: May 2010

We have investigated the interaction of hydrogen with Pt‐AlGaN/GaN Schottky barrier diodes (SBDs) using a low‐frequency capacitance‐voltage (C‐V) technique. At a frequency of 1kHz, the C‐V curve in hydrogen shifts toward negative bias values as compared with that in nitrogen. As the frequency decreases from 1kHz to 1Hz, the capacitance in hydrogen significantly increases and the fluctuations of the capacitance are observed. These C‐V characteristics are quite anomalous and have not been reported yet, suggesting the formation of interfacial polarization which could be attributable to hydrogen‐related dipoles. The fluctuation of the capacitance may be related to the alignment of the dipoles. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of ITO spreading layer on performance of blue light‐emitting diodes
Authors: Bogdanov M. V. , Bulashevich K. A. , Khokhlev O. V. , Evstratov I. Yu. , Ramm M. S. , Karpov S. Yu.
Published: May 2010

Operation of blue light emitting diodes with ITO spreading layers of various thicknesses deposited on top of the p‐contact layer is considered by simulations. Effects of the ITO layer on the current spreading in and the efficiency of light extraction from the LED dice are examined in detail. The electrical LED parameters, operation voltage and series resistance at a certain forward current, are found to be improved with the thickness of ITO films. In contrast, the optical parameters, external quantum efficiency and output power, become reduced with the thickness because of free‐carrier light absorption in the ITO films. These opposite trends make practically unrealistic simultaneous optimization of the electrical and optical parameters by varying the ITO layer properties only. An alternative way is suggested for improvement of the LED performance, based on optimization of light extraction from the LED due to a proper choice of the ITO parameters and of current spreading in the die due to an increase of doping level in the n‐contact layer. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Buffer‐trap and surface‐state effects on gate lag in AlGaN/GaN HEMTs
Authors: Horio Kazushige , Nakajima Atsushi
Published: May 2010

Two‐dimensional simulation of turn‐on characteristics of Al‐GaN/GaN HEMTs is performed in which both buffer traps and surface states are considered. It is studied how the so‐called gate lag is affected by these factors. It is shown that gate lag due to buffer traps can occur because in the off state where the gate voltage is negative, electrons are injected into the buffer layer and captured by the traps, leading to more negatively charged buffer layer. It is also shown that gate lag due to an electron‐trap‐type surface state can occur only when electron's gate tunneling is considered (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of unintentional arsenic incorporation into free‐standing zinc‐blende GaN and AlGaN layers grown by molecular beam epitaxy on GaAs substrates
Authors: Novikov S. V. , Zainal N. , Foxon C. T. , Kent A. J. , Luckert F. , Edwards P. R. , Martin R. W.
Published: May 2010

In this paper we have studied the unintentional incorporation of arsenic into thick (up to ∼75 μm) zinc‐blende (cubic) GaN and AlGaN layers grown by a plasma‐assisted molecular beam epitaxy (PA‐MBE) on (001) GaAs substrates. We present detailed studies of As incorporation into free‐standing zinc‐blende (Al)GaN by secondary ion mass spectroscopy (SIMS) and electron probe microanalysis (EPMA). We demonstrate that there is no significant arsenic contamination of zinc‐blende GaN layers and substrates due to diffusion of arsenic during the prolonged growths by PA‐MBE. Arsenic incorporation is limited to the first few hundred nanometers of the layer and it is due to initiation phase of the growth of zinc‐blende material, which involves use of arsenic as a surfactant to promote the growth of the cubic phase. These data have allowed us to determine the thickness of the unintentionally arsenic contaminated GaN region, which needs to be removed by polishing during production of free‐standing zinc‐blende GaN substrates. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Formation mechanism of Al‐depleted bands in MOVPE‐AlGaN layer on GaN template with trenches
Authors: Kuwano Noriyuki , Ezaki Tetsuya , Kurogi Takuya , Miyake Hideto , Hiramatsu Kazumasa
Published: May 2010

A microstructure in an AlGaN/GaN layer was analyzed in detail by means of transmission electron microscopy (TEM) and scanning electron microscopy (SEM) with special attention to the formation of steps on the surface. The AlGaN layer was grown by MOVPE on a GaN template with periodic trenches. It was revealed that there formed were Al‐depleted bands in the AlGaN layer. These bands were generated from rather lower regions in the AlGaN layer or those above the trenches, and run upwards. Some of them reached the top surface to connect a macro step. The formation mechanism of the Al‐depleted region is discussed in terms of thermodynamics. If the total bonding energy of atoms on the macro step of surface is assumed to be smaller than that of atoms on a flat surface, the Al‐depletion can be explained provided that the local equilibrium in concentration is conserved during the growth of AlGaN layer. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Plasma assisted LED wafer scribing and fabrication of Ag nanoparticle‐embedded LED
Authors: Lee Jong‐Moo , Bae Sung‐Bum , Youn Doo‐Hyub , Park Suntak , Ju Jung Jin , Jang Moon Sik , Jung Hyun Min , Kim Chang Tae
Published: May 2010

Two applications of plasma effects in fabrication of LEDs are introduced. One is scribing LED wafer by mechanical impacts of plasma, which is induced by laser ablation, to the bottom of LED wafer. The other one is the surface plasmon effect on light emission. Ag nano‐particles are formed on about 50‐nm thick p‐GaN epitaxial layer over multi‐quantum wells (MQWs) and an additional 150‐nm thick p‐GaN layer is grown again over the surface. As the result, the Ag nano‐particles are located within the overall p‐GaN epitaxial layer, very near to MQWs. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Semipolar GaInN/GaN light‐emitting diodes grown on honeycomb patterned substrates
Authors: Wunderer T. , Wang J. , Lipski F. , Schwaiger S. , Chuvilin A. , Kaiser U. , Metzner S. , Bertram F. , Christen J. , Shirokov S. S. , Yunovich A. E. , Scholz F.
Published: May 2010

Excellent semipolar GaN material quality can be obtained by growing inverse GaN pyramids on full 2 inch c‐plane sapphire when combining the advantages of defect reduction via FACELO and selective area growth for faceted surfaces. The nearly defect free material is obtained by structuring the mask into a honeycomb pattern. When realizing full GaInN/GaN LED structures on those templates a relatively broad emission is observed during electroluminescence measurements.

Furthermore, the dominant wavelength is found to be dependent on the applied current density. The pronounced shift is in good agreement with the wavelength shift along one single facet. Gas phase diffusion during the active area growth is believed to be the main reason for the varying indium content. The homogeneity could be influenced by changing the reactor pressure during the active area growth (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Highly defined and ordered top‐openings in TiO2 nanotube arrays
Authors: Albu Sergiu P. , Schmuki Patrik
Published: May 2010

We report a very simple and novel approach to produce anodic TiO2 nanotube arrays with highly defined and ordered tube openings. It is based on carrying out anodization through a slowly soluble photoresist coating. This eliminates the formation of undesired initiation layers on the tube tops and protects them to a certain extent from etching by the electrolyte.

magnified image

(© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantification of monosaccharides through multiple‐reaction monitoring liquid chromatography/mass spectrometry using an aminopropyl column
Authors: Hammad Loubna A. , Derryberry Dakota Z. , Jmeian Yazen R. , Mechref Yehia
Published: May 2010

A simple, sensitive, and reproducible quantitative liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was designed for the simultaneous quantification of monosaccharides derived from glycoprotein and blood serum using a multiple‐reaction monitoring (MRM) approach. Sialic acids and neutral monosaccharides were efficiently separated using an amino‐bonded silica phase column. Neutral monosaccharide molecules were detected as their aldol acetate anion adducts [M + CH3CO2]− using electrospray ionization in negative ion MRM mode, while sialic acids were detected as deprotonated ions [M–H]−. The new method did not require a reduction step, and exhibited very high sensitivity to carbohydrates with limits of detection of 1 pg for the sugars studied. The linearity of the described approach spanned over three orders of magnitude (pg to ng). The method was validated for monosaccharides originating from N‐linked glycans attached to glycoproteins and glycoproteins found in human blood serum. The method effectively quantified monosaccharides originating from as little as 1 µg of glycoprotein and 5 µL of blood serum. The method was robust, reproducible, and highly sensitive. It did not require reduction, derivatization or postcolumn addition of reagents. Copyright © 2010 John Wiley & Sons, Ltd.
Screening and analysis of the multiple absorbed bioactive components and metabolites in rat plasma after oral administration of Jitai tablets by high‐performance liquid chromatography/diode‐array detection coupled with electrospray ionization tandem mass spectrometry
Authors: Wang Shu‐Ping , Liu Lei , Wang Ling‐Ling , Jiang Peng , Zhang Ji‐Quan , Zhang Wei‐Dong , Liu Run‐Hui
Published: May 2010

Based on the serum pharmacochemistry technique and high‐performance liquid chromatography/diode‐array detection (HPLC/DAD) coupled with electrospray tandem mass spectrometry (HPLC/ESI‐MS/MS), a method for screening and analysis of the multiple absorbed bioactive components and metabolites of Jitai tablets (JTT) in orally dosed rat plasma was developed. Plasma was treated by methanol precipitation prior to liquid chromatography, and the separation was carried out on a Symmetry C18 column, with a linear gradient (0.1% formic acid/water/acetonitrile). Mass spectra were acquired in negative and positive ion modes, respectively. As a result, 26 bioactive components originated from JTT and 5 metabolites were tentatively identified in orally dosed rat plasma by comparing their retention times and MS spectra with those of authentic standards and literature data. It is concluded that an effective and reliable analytical method was set up for screening the bioactive components of Chinese herbal medicine, which provided a meaningful basis for further pharmacology and active mechanism research of JTT. Copyright © 2010 John Wiley & Sons, Ltd.
Robotic hip arthroscopy in human anatomy
Authors: Kather Jens , Hagen Monika E. , Morel Philippe , Fasel Jean , Markar Sheraz , Schueler Michael
Published: May 2010

Background

Robotic technology offers technical advantages that might offer new solutions for hip arthroscopy.

Methods

Two hip arthroscopies were performed in human cadavers using the da Vinci© surgical system. During both surgeries, a robotic camera and 5 or 8 mm da Vinci trocars with instruments were inserted into the hip joint for manipulation.

Results

Introduction of cameras and working instruments, docking of the robotic system and instrument manipulation was successful in both cases. The long articulating area of 5 mm instruments limited movements inside the joint; an 8 mm instrument with a shorter area of articulation offered an improved range of motion.

Conclusions

Hip arthroscopy using the da Vinci standard system appears a feasible alternative to standard arthroscopy. Instruments and method of application must be modified and improved before routine clinical application but further research in this area seems justified, considering the clinical value of such an approach. Copyright © 2010 John Wiley & Sons, Ltd.
Stability criteria for uncertain stochastic dynamic systems with time‐varying delays
Authors: Kwon O. M.
Published: May 2010

In this paper, the problem of delay‐dependent stability for uncertain stochastic dynamic systems with time‐varying delay is considered. Based on the Lyapunov stability theory, improved delay‐dependent stability criteria for the system are established in terms of linear matrix inequalities. Three numerical examples are given to show the effectiveness of the proposed method. Copyright © 2010 John Wiley & Sons, Ltd.
Airborne vision‐based mapping and classification of large farmland environments
Authors: Bryson Mitch , Reid Alistair , Ramos Fabio , Sukkarieh Salah
Published: May 2010

This paper presents a framework for integrating sensor information from an inertial measuring unit (IMU), global positioning system (GPS) receiver, and monocular vision camera mounted to a low‐flying unmanned aerial vehicle (UAV) for producing large‐scale terrain reconstructions and classifying different species of vegetation within the environment. The reconstruction phase integrates all of the sensor information using a statistically optimal nonlinear least‐squares bundle adjustment algorithm to estimate vehicle poses simultaneously to a highly detailed point feature map of the terrain. The classification phase uses feature descriptors based on the color and texture properties of vegetation observed in the vision data and uses the terrain information to build a georeferenced map of different types of vegetation. The resulting system can be used for a range of environmental monitoring missions such as invasive plant detection and biomass mapping. Experimental results of the algorithms are demonstrated in a “weed‐finding” mission over a large farmland area of the Australian outback. © 2010 Wiley Periodicals, Inc.
A cross‐layer framework for IPsec over satellite links
Authors: Roseti C. , Luglio M. , Fairhurst G. , Ramachandran S.
Published: May 2010

The traditional modular OSI‐layered architecture has served a major role in the development of a variety of protocols. However, as physical layer impairments become complex and time varying, a dynamic cross‐layer design can enable better performance. A Cross‐Layer Architecture (CLA) is proposed to improve performance of error‐tolerant applications running over UDP‐Lite. This approach to implementation introduces new challenges in protocol design, as well as in the area of security, where the study proposes a new method to enable IP security (IPsec) authentication and integrity services at the network layer. Target scenarios include satellite multicast for large‐scale delivery of data and video content. In this scenario, CLA can mitigate the effects of physical layer impairments and high latency. Numerical analysis has shown that a link design employing header compression and cross‐layer signalling may protect protocol headers and can reduce the probability of packet discard. To evaluate the feasibility of the CLA, these methods have been implemented as an extension to the IPsec protocol, named Cross‐Layer IPsec (CL‐IPsec). A satellite emulation platform was used to validate the implementation of CL‐IPsec and to evaluate the overall performance improvement resulting from the proposed CLA. Copyright © 2010 John Wiley & Sons, Ltd.
Experience with Delay‐Tolerant Networking from orbit
Authors: Ivancic W. , Eddy W. M. , Stewart D. , Wood L. , Northam J. , Jackson C.
Published: May 2010

We describe the first use from space of the Bundle Protocol for Delay‐Tolerant Networking (DTN) and lessons learned from experiments made and experience gained with this protocol. The Disaster Monitoring Constellation (DMC), constructed by Surrey Satellite Technology Ltd (SSTL), is a multiple‐satellite Earth‐imaging low‐Earth‐orbit sensor network in which recorded image swaths are stored onboard each satellite and later downloaded from the satellite payloads to a ground station. Store‐and‐forward of images with capture and later download gives each satellite the characteristics of a node in a disruption‐tolerant network. Originally developed for the ‘Interplanetary Internet,’ DTNs are now under investigation in an Internet Research Task Force (IRTF) DTN research group (RG), which has developed a ‘bundle’ architecture and protocol. The DMC is technically advanced in its adoption of the Internet Protocol (IP) for its imaging payloads and for satellite command and control, based around reuse of commercial networking and link protocols. These satellites' use of IP has enabled earlier experiments with the Cisco router in Low Earth Orbit (CLEO) onboard the constellation's UK‐DMC satellite. Earth images are downloaded from the satellites using a custom IP‐based high‐speed transfer protocol developed by SSTL, Saratoga, which tolerates unusual link environments. Saratoga has been documented in the Internet Engineering Task Force (IETF) for wider adoption. We experiment with the use of DTNRG bundle concepts onboard the UK‐DMC satellite, by examining how Saratoga can be used as a DTN ‘convergence layer’ to carry the DTNRG Bundle Protocol, so that sensor images can be delivered to ground stations and beyond as bundles. Our practical experience with the first successful use of the DTNRG Bundle Protocol in a space environment gives us insights into the design of the Bundle Protocol and enables us to identify issues that must be addressed before wider deployment of the Bundle Protocol. Published in 2010 by John Wiley & Sons, Ltd.
The relevance of ecocentrism, personal development and transformational leadership to sustainability and identity
Authors: Hay Robert
Published: May 2010

Identity is formed gradually as we mature through personal development within societal (and natural) context. As such, it is group informed but individually directed and is strongly influenced by our family, community, place and natural surroundings. Together, these interwoven aspects of our lives help us each to create an identity that is unique and that should be able to be sustained over time. However, because we live within collectives and places that have often become less sustainable of late, this has a corresponding effect on our identity. The interactive relationship between identity and sustainability is therefore integral to how we understand and then address issues that currently confront us all. To investigate this relationship, three aspects of identity are considered together: the significance of an ecocentric philosophy, personal development oriented to service and transformational leadership. Interweaving these related reflections goes beyond a more limited view of identity, providing new directions for sustainability. Copyright © 2010 John Wiley & Sons, Ltd and ERP Environment.
Unstable identities: stable unsustainability
Authors: Strannegård Lars , Dobers Peter
Published: May 2010

The identity concept has emerged as a key analytical concept in the social sciences in the past decades. In both scientific accounts and everyday use, the identity concept has traditionally been seen as something that individuals possess. This view has however been heavily criticized by a social identity strand of social science, where identity is a matter of a negotiation where different social roles are learned in relations with others. The relational view of identities creates some serious problems for the sustainability challenge. In a world of relational identities, individuals are engaged in identity‐creating interactions every day. Key problems are that the interactions, in urban environments, are highly commercialized; consumption cues are emotionally based and speak to our senses, and outnumber the competing cues several times over. Sustainable lifestyles are thus very fragile. Copyright © 2010 John Wiley & Sons, Ltd and ERP Environment.
The surface profile and biocompatibility of hydroxyapatiteblasted gold membrane as a periodontal guided tissue regeneration membrane
Authors: Jin Kangsik , Youn Lee Doug , Je Jina , Keun Lee Yong , Nam Kim Kyoung , Mahn Kim Kwang
Published: May 2010

Guided tissue regeneration (GTR) membrane is essential for periodontal surgery, GTR membrane can guide successful bone tissue formation. The aim of this study is to assess morphologic property and biocompatibility of hydroxyapatite (HA) blasted gold membrane as a periodontal GTR membrane. 99.99 gold (LS Nikko, Korea) was rolled to 0.025∼0.050 mm thickness, and then, blasted with hydroxyapatite powder (5 ∼ 25 µm, Ossgen, Korea) onto the rolled gold sheets. Contact angle measurement of non‐blasted and HA‐blasted surface was performed. And, scanning electron microscopy analysis (simple surface profile observation and observation after attachment of human osteosarcoma cell) was performed. In implantation test using adult dog, Ti‐membrane (Implantium, Suwon, Korea) was used as a control group, and HA‐blasted gold membrane was used as a experimental group. Contact angle of HA‐blasted gold membrane was higher than that of non‐blasted gold surface (p < 0.05). In SEM analysis, HA‐blasted gold membrane showed roughened surface and attachment of MG‐63 cell was more than that of non‐blasted gold surface. There were not any specific clinical symptoms and histological signs in implantation test. This result shows that HA‐blasted gold membrane has a possibility as promising periodontal GTR membrane. Copyright © 2010 John Wiley & Sons, Ltd.
Effect of temperature on free β‐human chorionic gonadotropin and pregnancy‐associated plasma protein‐A concentration
Authors: Cruz J. , Cruz G. , Minekawa R. , Maiz N. , Nicolaides K. H.
Published: May 2010

Objective

To examine the effect of the duration of storage of serum and whole blood at different controlled temperatures on the concentrations of both serum free‐β‐human chorionic gonadotropin (β‐hCG) and pregnancy‐associated plasma protein‐A (PAPP‐A) in first‐trimester screening for aneuploidies.

Methods

The concentrations of free β‐hCG and PAPP‐A were measured in samples collected from 10 pregnant women and stored as whole blood or serum for 1–8 days at 4, 20 or 40 °C. The concentrations measured were adjusted to take day‐to‐day variations into account and were expressed as a percentage of the values on day 0. In a second study involving 10 pregnant women, free β‐hCG was measured at 10 min and at 2, 4, 8 and 12 h after collection and storage at 30 or 40 °C, either as separated serum or as whole blood.

Results

The change in the levels of PAPP‐A in the separated serum at all three temperatures and in whole blood at 4 °C was always less than 10% throughout the 8 days of storage. In whole blood stored at 20 and 40 °C, the percentage variation was less than 10% only if the storage period was shorter than 4 days. The concentration of free β‐hCG was not altered by storage of either whole blood or separated serum at 4 °C throughout the 8 days of storage. At 20 °C, reliable results were obtained only if the maximum storage time was 2 days for separated serum and 1 day for whole blood. At 30 °C, reliable results were obtained only if the samples were analyzed within 2 h of collection, and at 40 °C the concentrations increased by more than 50% within 2 h and by about 500% after 1 day of storage.

Conclusion

In first‐trimester screening for aneuploidies, analysis of blood samples should be undertaken within a few minutes of collection, otherwise the samples should be refrigerated at 4 °C throughout the interval between collection and analysis. Copyright © 2010 ISUOG. Published by John Wiley & Sons, Ltd.
Value of transvaginal ultrasound in assessing severity of pelvic endometriosis
Authors: Holland T. K. , Yazbek J. , Cutner A. , Saridogan E. , Hoo W. L. , Jurkovic D.
Published: May 2010

Objective

The objective of this study was to examine the ability of preoperative transvaginal ultrasound (TVS) scanning to assess the severity of pelvic endometriosis.

Methods

Consecutive women with clinically suspected or proven pelvic endometriosis, who were booked for laparoscopy, were invited to join the study. The severity of endometriosis was assessed preoperatively using TVS and the findings were compared with the results obtained by laparoscopy using the American Society for Reproductive Medicine (ASRM) classification.

Results

In total, 201 women had preoperative TVS and laparoscopies. Of these, no endometriosis was found at laparoscopy for 62/201 (30.8%; 95% CI, 24.8–37.5), whereas 33/201 (16.4%; 95% CI, 11.9–22.2) had minimal endometriosis, 31/201 (15.4%; 95% CI, 11.1–21.1) had mild endometriosis, 27/201 (13.4%; 95% CI, 9.4–18.8) had moderate endometriosis and 48/201 (23.9%; 95% CI, 18.5–30.2) had severe endometriosis. The sensitivity and specificity of the TVS diagnosis of severe pelvic endometriosis were 0.85 (95% CI, 0.716–0.934) and 0.98 (95% CI, 0.939–0.994), respectively, and the positive and negative likelihood ratios were 43.5 (95% CI, 14.1–134) and 0.15 (95% CI, 0.075–0.295), respectively. Overall, there was a good level of agreement between ultrasound and laparoscopy in identifying absent, minimal, mild, moderate and severe disease (quadratic weighted kappa = 0.786). The mean ASRM score difference between TVS and laparoscopy in assessing severity of endometriosis was − 2.398 (95% CI, − 4.685 to − 0.1112) and the limits of agreement were − 34.62 (95% CI, − 38.54 to − 30.709) to 29.83 (95% CI, 25.91–33.74).

Conclusions

TVS is a good test for assessing the severity of pelvic endometriosis. TVS is particularly accurate in detecting severe disease, which could facilitate more effective triaging of women for appropriate surgical care. Copyright © 2010 ISUOG. Published by John Wiley & Sons, Ltd.
Infant categorization
Authors: Rakison David H. , Yermolayeva Yevdokiya
Published: May 2010

In this article, we review the principal findings on infant categorization from the last 30 years. The review focuses on behaviorally based experiments with visual preference, habituation, object examining, sequential touching, and inductive generalization procedures. We propose that although this research has helped to elucidate the ‘what’ and ‘when’ of infant categorization, it has failed to clarify the mechanisms that underpin this behavior and the development of concepts. We outline a number of reasons for why the field has failed in this regard, most notably because of the context‐specific nature of infant categorization and a lack of ground rules in interpreting data. We conclude by suggesting that one remedy for this issue is for infant categorization researchers to adopt more of an interdisciplinary approach by incorporating imaging and computational methods into their current methodological arsenal.WIREs Cogn Sci2010 1 894–905

This article is categorized under:

Psychology > Development and Aging
Perception and action
Authors: Creem‐Regehr Sarah H. , Kunz Benjamin R.
Published: May 2010

The phrase perception and action is used widely but in diverse ways in the context of the relationship between perceptual and motor processes. This review describes and integrates five perspectives on perception and action which rely on both neurophysiological and behavioral levels of analysis. The two visual systems view proposes dissociable but interactive systems for conscious processing of objects/space and the visual control of action. The integrative view proposes tightly calibrated but flexible systems for perception and motor control in spatial representation. The embodied view posits that action underlies perception, involving common coding or motor simulation systems, and examines the relationship between action observation, imitation, and the understanding of intention. The ecological view emphasizes environmental information and affordances in perception. The functional view defines the relationship between perception, action planning, and semantics in goal‐directed actions. Although some of these views/approaches differ in significant ways, their shared emphasis on the importance of action in perception serves as a useful unifying framework. WIREs Cogn Sci 2010 1 800–810

This article is categorized under:

Psychology > Motor Skill and Performance
Light detection and ranging measurements of wake dynamics. Part II: two‐dimensional scanning
Authors: Trujillo Juan‐José , Bingöl Ferhat , Larsen Gunner C. , Mann Jakob , Kühn Martin
Published: May 2010

A nacelle‐mounted lidar system pointing downstream has been used to measure wind turbine wake dynamics. The new measurement and data analysis techniques allow estimation of quasi‐instantaneous wind fields in planes perpendicular to the rotor axis. A newly developed wake tracking procedure delivers the instantaneous transversal wake position which is quantitatively compared with the prediction of the Dynamic Wake Meandering model. The results, shown for two 10‐min time series, suggest that the conjecture of the wake behaving as a passive tracer is a fair approximation; this corroborates and expands the results of one‐dimensional measurements already presented in the first part of this paper. Consequently, it is now possible to separate the deterministic and turbulent parts of the wake wind field, thus enabling capturing the wake in the meandering frame of reference. The results correspond, qualitatively and to some extent quantitatively, to the expectations from CFD simulations which are compared in the paper. Copyright © 2010 John Wiley & Sons, Ltd.