bluuebunny/crossref_metadata_2025 huggingface dataset:
Les sciences humaines et la critique de la raison stratégique
Authors: Wasinski Christophe
Published: March 2016

Faut-il tenir pour acquis le raisonnement stratégique qui affirme que la violence militaire est un moyen rationnellement utilisable au service de fins politiques ? Cet article traite ce problème à partir d’une relecture de travaux issus des sciences humaines (histoire, anthropologie ou encore études en communication) autres que les Relations internationales. À l’aide de ceux-ci, il met en évidence le fait que le raisonnement stratégique doit sa continuité aux intérêts de certains acteurs responsables de cadrages très sélectifs, pour ne pas dire biaisés, des effets de l’usage de la force. Pour prendre la pleine mesure de ce phénomène, une perspective dédisciplinarisée, voire indisciplinée, s’impose.
Les études stratégiques sont-elles rationalistes et matérialistes ? « Nouvelles études de sécurité » et pensée stratégique
Authors: Vennesson Pascal
Published: March 2016

Les tenants des « nouvelles études de sécurité » ont au cours des deux dernières décennies avancé une critique de grande ampleur de la contribution de la stratégie à l’étude de la sécurité internationale et, plus généralement, des relations internationales dans leur ensemble. Ils estiment que le soubassement épistémologique des études stratégiques, spécifiquement leurs postulats rationaliste et matérialiste, constitue un grave handicap. Toutefois, ce défi vigoureux et influent n’a, jusqu’à présent, pas été relevé. On montrera ici que les études stratégiques échappent très largement aux accusations des tenants de la sécurité élargie et on répondra aux objections épistémologiques qu’ils ont avancées.
Des études critiques de sécurité au démantèlement de la sécurité
Authors: Çalkivik Asli
Published: March 2016

Le projet d’une approche critique de la sécurité est devenu un domaine de recherche dynamique, donnant naissance à des sous-champs distincts tels que les études féministes de sécurité et les études critiques du terrorisme. Mais un nombre croissant de chercheurs critiques ont commencé à remettre en question les réalisations de ce programme de recherche au cours des dernières années. Ils soulignent la façon dont les discours critiques sur la sécurité prennent l’apparence d’une nouvelle orthodoxie et deviennent complices de la reproduction des rapports de pouvoir existants. D’autres vont plus loin encore et déclarent la « mort » des approches critiques de la sécurité. Dans cet article, je passe en revue ces débats émergents sur le goulot d’étranglement rencontré par les études critiques de la sécurité et je détaille les critiques concernant l’état actuel des études critiques de sécurité.
Construction et légitimation initiales des standards transnationaux de responsabilité des entreprises : entre actions intentionnelles et contraintes institutionnelles
Authors: Stamm Christoph
Published: March 2016

Les acteurs engagés dans le processus de construction d’une norme transnationale dans le domaine de la responsabilité des entreprises (rse) effectuent différentes formes de travail institutionnel afin de mener leur projet à terme. En mettant l’accent sur les processus et sur les acteurs, cette recherche compare la mise en oeuvre de deux standards : le Pacte mondial (Global Compact) de l’onuet la normeiso26000 de l’Organisation internationale de normalisation. L’analyse approfondit notre compréhension des liens entre les types de travail institutionnel et les différentes dimensions de la légitimité. Elle révèle les mécanismes de légitimation dans la construction initiale d’une normerse. Si le travail institutionnel est toujours d’une importance cruciale, il prend différentes formes selon les conditions propres à chaque initiative.
Le développement inégal et combiné des révolutions : une réflexion critique sur la relation interdisciplinaire entre sociologie historique et Relations internationales
Authors: Viger Jonathan
Published: March 2016

Cet article vise à initier le lectorat francophone au programme de recherche de la sociologie historique internationale (shi) et à la théorie du développement inégal et combiné (dic) comme tentative de synthèse transdisciplinaire entre sociologie historique et Relations internationales (ri). Cette tentative sera analysée à travers l’étude des révolutions, en tant qu’objet de recherche emblématique de la fracture épistémique entre les deux disciplines. Nous déconstruirons le projet transdisciplinaire du dic pour démontrer comment celui-ci ne répond pas aux objectifs initiaux de la shi en termes de sociologisation et d’historicisation des RI. Nous tenterons par la suite de réactiver ces objectifs et de reformuler la relation interdisciplinaire entre sociologie et ri au moyen d’une réflexion épistémologique et historiciste prenant comme base la théorie des relations sociales de propriété (trsp).
Gas flow dependence of atmospheric pressure plasma needle discharge characteristics
Authors: Qian Muyang , Yang Congying , Liu Sanqiu , Chen Xiaochang , Ni Gengsong , Wang Dezhen
Published: March 2016

In this paper, a two-dimensional coupled model of neutral gas flow and plasma dynamics is presented to explain the gas flow dependence of discharge characteristics in helium plasma needle at atmospherics pressure. The diffusional mixing layer between the helium jet core and the ambient air has a moderate effect on the streamer propagation. The obtained simulation results present that the streamer shows the ring-shaped emission profile at a moderate gas flow rate. The key chemical reactions which drive the streamer propagation are electron-impact ionization of helium neutral, nitrogen and oxygen molecules. At a moderate gas flow rate of 0.5 slm, a significant increase in propagation velocity of the streamer is observed due to appropriate quantity of impurities air diffuse into the helium. Besides, when the gas flow rate is below 0.35 slm, the radial density of ground-state atomic oxygen peaks along the axis of symmetry. However, when the gas flow rate is above 0.5 slm, a ring-shaped density distribution appears. The peak density is on the order of 1020 m−3 at 10 ns in our work.
Combined surface-activated bonding technique for low-temperature hydrophilic direct wafer bonding
Authors: He Ran , Fujino Masahisa , Yamauchi Akira , Suga Tadatomo
Published: March 2016

A combined surface-activated bonding technique is studied for surface activation and water management to improve the hydrophilic SiO2–SiO2 bonding quality. Prebonding treatment involving a Si-containing Ar beam bombardment and prebonding attach-detach is employed prior to wafer bonding in vacuum. The results of bonding strength measurement, Monte Carlo simulation, and surface analysis by Fourier transform infrared spectroscopy are reported. A mechanism is proposed to better understand the nature of the hydrophilic bonding at low temperatures of no more than 200 °C. We suggest that the Si-containing Ar beam modifies the SiO2 surfaces by Si enrichment to make them more reactive for OH adsorption, while the prebonding attach and detach facilitate a further increase in the number of OH and the removal of excess trapped H2O prior to bonding, respectively. As a consequence, SiO2–SiO2 bonding strength close to the Si bulk fracture energy can be achieved after low-temperature annealing.
Study on initial current leakage spots in CoFeB-capped MgO tunnel barrier by conductive atomic force microscopy
Authors: Sato Soshi , Honjo Hiroaki , Ikeda Shoji , Ohno Hideo , Endoh Tetsuo , Niwa Masaaki
Published: March 2016

Although a microscopic study on a MgO tunnel barrier by atomic force microscopy has been required to study the reliability of magnetic tunnel junctions, the deterioration of bare MgO due to the adsorption of H2O and CO2 has been a problem. For an accurate evaluation of the initial current leakage spots distributed in a MgO tunnel barrier, a CoFeB-capped MgO tunnel barrier structure is proposed for evaluation by means of conductive atomic force microscopy. The CoFeB capping layer thickness was optimized to be 2.0 nm to prevent H2O and CO2 adsorption on the MgO and to minimize the series resistance due to the capping layer. The initial current leakage spot density of the MgO tunnel barrier with the optimized CoFeB capping layer exponentially increased as the thickness of the MgO tunnel barrier decreased from 1.6 to 0.8 nm, and was 157 spots/µm2 at the MgO thickness of 1.2 nm and the bias voltage of 0.5 V.
Improved linearity and reliability in GaN metal–oxide–semiconductor high-electron-mobility transistors using nanolaminate La2O3/SiO2 gate dielectric
Authors: Hsu Ching-Hsiang , Shih Wang-Cheng , Lin Yueh-Chin , Hsu Heng-Tung , Hsu Hisang-Hua , Huang Yu-Xiang , Lin Tai-Wei , Wu Chia-Hsun , Wu Wen-Hao , Maa Jer-Shen , Iwai Hiroshi , Kakushima Kuniyuki , Chang Edward Yi
Published: March 2016

Improved device performance to enable high-linearity power applications has been discussed in this study. We have compared the La2O3/SiO2 AlGaN/GaN metal–oxide–semiconductor high-electron-mobility transistors (MOS-HEMTs) with other La2O3-based (La2O3/HfO2, La2O3/CeO2 and single La2O3) MOS-HEMTs. It was found that forming lanthanum silicate films can not only improve the dielectric quality but also can improve the device characteristics. The improved gate insulation, reliability, and linearity of the 8 nm La2O3/SiO2 MOS-HEMT were demonstrated.
Two-dimensional characterization of ion-implantation damage in GaN Schottky contacts using scanning internal photoemission microscopy
Authors: Shiojima Kenji , Murase Shingo , Yamamoto Shingo , Mishima Tomoyoshi , Nakamura Tohru
Published: March 2016

Nitrogen-ion-implantation damage on GaN has been clearly visualized using scanning internal photoemission microscopy. Ni Schottky contacts were formed on selectively N-ion-implanted n-GaN surfaces at 80 keV with an ion dose of 1 × 1014 or 1 × 1015 cm−2, and a photocurrent was detected by focusing and scanning a laser beam over the contacts. We found that the photocurrent decreased in the implanted regions due to an increase in the Schottky barrier and carrier depletion. Photocurrent maps showed that the induced damage did not spread from the implanted regions within the spatial resolution of the equipment. We confirmed that this method is a powerful tool for mapping implanted highly resistive regions.
High-power and high-temperature operation of an InGaN laser over 3 W at 85 °C using a novel double-heat-flow packaging technology
Authors: Nozaki Shinichiro , Yoshida Shinji , Yamanaka Kazuhiko , Imafuji Osamu , Takigawa Shinichi , Katayama Takuma , Tanaka Tsuyoshi
Published: March 2016

In this paper, we present a novel double-heat-flow (DHF) packaging technology of an indium gallium nitride (InGaN) laser diode (LD) promising for high-power and high-temperature operation. The LD chip on a submount is covered by another III–nitride ceramic submount, which reduces the thermal resistance, facilitating the assembly in a commercial compact package. A DHF LD operates with a maximum output power of over 3 W at 85 °C as well as that of 1.9 W even at 140 °C.
Mapping of Si/SiC p–n heterojunctions using scanning internal photoemission microscopy
Authors: Shingo Masato , Liang Jianbo , Shigekawa Naoteru , Arai Manabu , Shiojima Kenji
Published: March 2016

We demonstrated the two-dimensional characterization of p+-Si/n−-SiC heterointerfaces by scanning internal photoemission microscopy (SIPM). In internal photoemission spectra, a linear relationship was found between the square root of photoyield (Y) and photon energy, and the threshold energy (qV
th) was reasonably obtained to be 1.34 eV. From the SIPM results, Y and qV
th maps were successfully obtained, and nanometer-deep gaps in the junction were sensitively visualized as a pattern. These results suggest that this method is a powerful tool for investigating the inhomogeneity of heterojunctions as well as their carrier transport properties.
Electronic and optical characteristics of an m-plane GaN single crystal grown by hydride vapor phase epitaxy on a GaN seed synthesized by the ammonothermal method using an acidic mineralizer
Authors: Kojima Kazunobu , Tsukada Yusuke , Furukawa Erika , Saito Makoto , Mikawa Yutaka , Kubo Shuichi , Ikeda Hirotaka , Fujito Kenji , Uedono Akira , Chichibu Shigefusa F.
Published: March 2016

Fundamental electronic and optical properties of a low-resistivity m-plane GaN single crystal, which was grown by hydride vapor phase epitaxy on a bulk GaN seed crystal synthesized by the ammonothermal method in supercritical ammonia using an acidic mineralizer, were investigated. The threading dislocation and basal-plane staking-fault densities of the crystal were around 104 cm−2 and less than 100 cm−1, respectively. Oxygen doping achieved a high electron concentration of 4 × 1018 cm−3 at room temperature. Accordingly, a photoluminescence (PL) band originating from the recombination of hot carriers was observed at low temperatures, even under weak excitation conditions. The simultaneous realization of low-level incorporation of Ga vacancies (VGa) less than 1016 cm−3 was confirmed by using the positron annihilation technique. Consistent with our long-standing claim that VGa complexes are the major nonradiative recombination centers in GaN, the fast-component PL lifetime of the near-band-edge emission at room temperature longer than 2 ns was achieved.
On the utility of the ionosonde Doppler‐derived EXB drift during the daytime
Authors: Joshi L. M. , Sripathi S.
Published: March 2016

Vertical EXB drift measured using the ionosonde Doppler sounding during the daytime suffers from an underestimation of the actual EXB drift because the reflection height of the ionosonde signals is also affected by the photochemistry of the ionosphere. Systematic investigations have indicated a fair/good correlation to exist between the C/NOFS and ionosonde Doppler‐measured vertical EXB drift during the daytime over magnetic equator. A detailed analysis, however, indicated that the linear relation between the ionosonde Doppler drift and C/NOFS EXB drift varied with seasons. Thus, solar, seasonal, and also geomagnetic variables were included in the Doppler drift correction, using the artificial neural network‐based approach. The RMS error in the neural network was found to be smaller than that in the linear regression analysis. Daytime EXB drift was derived using the neural network which was also used to model the ionospheric redistribution in the SAMI2 model. SAMI2 model reproduced strong (weak) equatorial ionization anomaly (EIA) for cases when neural network corrected daytime vertical EXB drift was high (low). Similar features were also observed in GIM TEC maps. Thus, the results indicate that the neural network can be utilized to derive the vertical EXB drift from its proxies, like the ionosonde Doppler drift. These results indicate that the daytime ionosonde measured vertical EXB drift can be relied upon, provided that adequate corrections are applied to it.
Dynamics of the opposite‐verging subduction zones in the Taiwan region: Insights from numerical models
Authors: Lin Shu‐Chuan , Kuo Ban‐Yuan
Published: March 2016

The Taiwan mountain belt between the Eurasian and the Philippine Sea plate is a rare example for an orogen bracketed by two opposite‐verging subduction zones. The influences of the double subduction zones on regional dynamics have long remained unknown. In this study lithospheric deformation and mantle circulation in the Taiwan region are calculated with double subduction‐collision models. The results show that the limitedly deformed subducted Eurasian plate separates the highly deforming orogen above from the highly deforming mantle below. The edge flow driven by the rollback of the Philippine Sea slab dominates in the asthenosphere primarily as a result of the longer slab if the gap between the two slabs beneath Taiwan is sufficiently wide. The induced toroidal current gives rise to a pattern of seismic anisotropy compatible with that measured with teleseismic phases and coincidentally accordant with the strike of the orogen. The additional presence of a frequently hypothesized lithospheric fragment or slab tear disrupts the toroidal circulation and mars the model predictions for seismic anisotropy. We found that the rollback of the Eurasian slab deflects the plate downward and neutralizes the uplift, posing difficulty to models with Eurasian slab extending too far north. These results bolster the view that the Taiwan mountain belt is a subduction‐dominated orogen and both subduction zones play a key role on regional dynamics. Conceptual models specifically developed for large‐scale continent‐continent collision zones that have been commonly applied to the Taiwan region are inadequate for this ocean‐continent, opposite‐verging subduction‐collision system.
Simulating the Black Saturday 2009 smoke plume with an interactive composition‐climate model: Sensitivity to emissions amount, timing, and injection height
Authors: Field Robert D. , Luo Ming , Fromm Mike , Voulgarakis Apostolos , Mangeon Stéphane , Worden John
Published: March 2016

We simulated the high‐altitude smoke plume from the early February 2009 Black Saturday bushfires in southeastern Australia using the NASA Goddard Institute for Space Studies ModelE2. To the best of our knowledge, this is the first single‐plume analysis of biomass burning emissions injected directly into the upper troposphere/lower stratosphere (UTLS) using a full‐complexity composition‐climate model. We compared simulated carbon monoxide (CO) to a new Aura Tropospheric Emission Spectrometer/Microwave Limb Sounder joint CO retrieval, focusing on the plume's initial transport eastward, anticyclonic circulation to the north of New Zealand, westward transport in the lower stratospheric easterlies, and arrival over Africa at the end of February. Our goal was to determine the sensitivity of the simulated plume to prescribed injection height, emissions amount, and emissions timing from different sources for a full‐complexity model when compared to Aura. The most realistic plumes were obtained using injection heights in the UTLS, including one drawn from ground‐based radar data. A 6 h emissions pulse or emissions tied to independent estimates of hourly fire behavior produced a more realistic plume in the lower stratosphere compared to the same emissions amount being released evenly over 12 or 24 h. Simulated CO in the plume was highly sensitive to the differences between emissions amounts estimated from the Global Fire Emissions Database and from detailed, ground‐based estimates of fire growth. The emissions amount determined not only the CO concentration of the plume but also the proportion of the plume that entered the stratosphere. We speculate that this is due to either or both nonlinear CO loss with a weakened OH sink or plume self‐lofting driven by shortwave absorption of the coemitted aerosols.
Ultrafast Multidimensional Laplace NMR Using a Single‐Sided Magnet
Authors: King Jared N. , Lee Vanessa J. , Ahola Susanna , Telkki Ville‐Veikko , Meldrum Tyler
Published: March 2016

Laplace NMR (LNMR) consists of relaxation and diffusion measurements providing detailed information about molecular motion and interaction. Here we demonstrate that ultrafast single‐ and multidimensional LNMR experiments, based on spatial encoding, are viable with low‐field, single‐sided magnets with an inhomogeneous magnetic field. This approach shortens the experiment time by one to two orders of magnitude relative to traditional experiments, and increases the sensitivity per unit time by a factor of three. The reduction of time required to collect multidimensional data opens significant prospects for mobile chemical analysis using NMR. Particularly tantalizing is future use of hyperpolarization to increase sensitivity by orders of magnitude, allowed by single‐scan approach.
Multi‐stimuli responsive shape memory polymers synthesized by using reaction‐induced phase separation
Authors: Zhang Yufen , Jiang Xue , Wu Ronglan , Wang Wei
Published: March 2016

Thermo‐induced multishape memory polymers are a growing focus of smart materials because of its promising applications. Multishape memory effect is generally attained by using polymers with broad phase transition and multiphase polymers. The latter is of particular interest for copolymerization and polymer compositing. One requirement has to be fulfilled to achieve multishape memory effect, which is to have two reversible phase transitions. In this study, we report synthesis of polymer composite composed of strong segregated polymers by using reaction‐induced phase separation. We demonstrate the method by using polyurethane (PU) and poly(methacrylic acid) (PMAA). With adjusting the weight ratio, the polymer composites exhibit a phase spectrum from phase separation to miscible composite. The composite with PU/PMAA =3:1 demonstrated triple‐shape memory effect. Based on the results, we argued the effect of segregation on the shape memory effect for polymer composites. With the addition of PMAA, the polymer composite also exhibits pH/water‐induced shape memory effect. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43534.
Thermal stability, flame retardance, and mechanical properties of polyamide 66 modified by a nitrogen–phosphorous reacting flame retardant
Authors: Lyu Wenyan , Cui Yihua , Zhang Xujie , Yuan Jingyao , Zhang Wei
Published: March 2016

Flame‐retardant polyamide 66 (PA66) was prepared by the polymerization between PA66 prepolymer and N‐benzoic acid (ethyl‐N‐benzoic acid formamide) phosphamide (NENP). Compared with the pure PA66, the flame‐retardant PA66 exhibited better thermal stability, as indicated by thermogravimetric analysis results. The limiting oxygen index was 28% and the UL‐94 test results of the flame‐retardant PA66 indicated a V‐0 rating when the content of the NENP prepolymer was 5 wt %. The flammability and flame‐retardant mechanism of PA66 were also studied with cone calorimetry and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, respectively. The mechanical properties results show that the flame‐retardant PA66 resin had favorable mechanical properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43538.
Evaluation of polymerization shrinkage in dental restorative experimental composites based: BisGMA/TEGDMA, filled with MMT
Authors: Campos Luiza Mello de Paiva , Boaro Letícia Cidreira , Ferreira Henrique Perez , dos Santos Letícia Karine Gomes , dos Santos Tamiris Ribeiro , Parra Duclerc Fernandes
Published: March 2016

This work concerns to the investigation of the polymerization shrinkage and mechanical properties in dental restoratives experimental composites filled with nano clay Montmorilonite (MMT) Cloisite® 10A nanoparticles, in glycidyl methacrylate resin, using experimental composites filled with silanized Aerosil OX‐50 Silica as a control group. Six formulations with BisGMA/TEGDMA based polymeric matrix (three added with MMT and three added with silanized silica as filler) containing 50, 60, and 70 wt % were investigated. Characterization of the experimental composites was established with the following analyses: Scanning Electron Microscope, (SEM); Thermo‐Mechanical Analysis, (TMA) for Shrinkage Polymerization; Differential Scanning Calorimetry Analysis (DSC); Knoop Micro Hardness analysis; X‐ray Diffraction (XRD); Degree of Conversion (DC); Elastic Modulus and Flexural Strength; Transmission Electron Microscopy (TEM). Statistical Analyses were realized using two‐way ANOVA (type and amount of filler) and Tukey's test. TMA results showed that composites filled with MMT nanoparticle present statistically lower polymerization shrinkage values and statistically high degree of conversion in all formulations tested, when compared to composites filled with silanized silica. XRD and TEM analyses showed evidences of the intercalation phenomenon in the MMT nanoparticles in relation to BisGMA/TEGDMA polymeric matrix. However, for Flexural Strength, groups filled with MMT nanoparticle showed statistically lower values in all concentration tested. At high filler concentration it was observed the appearance of tactoids and functionalization of MMT nanoparticle did not promote a strong interface adhesion between polymeric matrix and filler. In order to adjust the mechanical properties, it would be convenient to promote the concentration optimization of MMT nanoparticles. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43543.
Physical and antibacterial properties of polyvinyl alcohol films reinforced with quaternized cellulose
Authors: Hu Dongying , Wang Lijuan
Published: March 2016

Hydroxypropyltrimethylammonium chloride cellulose (CM) was homogeneously synthesized in a NaOH/urea aqueous solution. CM was blended in a polyvinyl alcohol (PVA) matrix to produce composite films via co‐regeneration from the alkaline solution. The PVA film and the blend films were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction measurements and scanning electron microscopy. The mechanical properties, water swelling ratio, hydrophobicity, light transmission, and antibacterial activity against Staphylococcus aureus and Escherichia coli were also evaluated. The results showed that CM could interact with PVA by hydrogen bonding and exhibit an obvious reinforcement effect. The addition of CM improved the surface roughness, hydrophobicity and water swelling ratio, especially, the antibacterial activity. However, compared with neat PVA film, the elasticity and optical transmission decreased. The increased tensile strength, powerful antibacterial activity, and medium light transmission indicate that the biocompatible blend film will become an exceptional alternative in functional bio‐material field. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43552.
Phenylene‐Bridged Core‐Modified Planar Aromatic Octaphyrin: Aromaticity, Photophysical and Anion Receptor Properties
Authors: Karthik Ganesan , Cha Won‐Young , Ghosh Arindam , Kim Taeyeon , Srinivasan A. , Kim Dongho , Chandrashekar Tavarekere K.
Published: March 2016

The synthesis of a planar expanded meso porphyrin with an intramolecular para‐phenylene‐bridged core is reported. The planarity of the octaphyrin macrocycle was confirmed by single‐crystal X‐ray structural analysis, in which the bridged para‐phenylene unit deviated by 27° from the mean macrocyclic plane. Spectroscopic analyses and theoretical calculations suggested that the macrocycle was Hückel aromatic and followed a major [34 π] single‐conjugation pathway, which indicated that the bridging para‐phenylene unit was not involved in the macrocyclic conjugation. Analysis of the photophysical properties of this system by steady‐state absorption/fluorescence spectroscopy and transient absorption spectroscopy revealed moderate enhancement in the parameters of the octaphyrin as compared to its non‐bridged octaphyrin congeners, which was attributed to the planarity and rigidity of the macrocycle as imposed by the bridging para‐phenylene unit. Preliminary anion‐binding studies revealed that the protonated macrocycle bound selectively with chloride ions through N−H⋅⋅⋅Cl hydrogen‐bonding interactions.
Preparation of Homogeneous Solid Samples for Reproducible and Quantitative MALDI
Authors: Ahn Sung Hee , Park Kyung Man , Moon Jeong Hee , Lee Seong Hoon , Kim Myung Soo
Published: March 2016

Preparing samples with good homogeneity is one of the requirements for generating reproducible matrix‐assisted laser desorption ionization (MALDI) spectra and for using them in analyte quantification. Thus far, we have not been successful in producing homogeneous solid samples from popular matrixes apart from α‐cyano‐4‐hydroxycinnamic acid (CHCA). In this work, we demonstrate the production of an outwardly homogeneous solid sample by loading a methanol solution of a matrix into a shallow reservoir on a coated MALDI sample plate and then vacuum‐drying it. Out of ten popular matrixes tested, seven yielded homogeneous samples. These were 9‐aminoacridine, 6‐aza‐2‐thiothymine, CHCA, 2,5‐dihydroxybenzoic acid, ferulic acid, sinapinic acid, and 2,4,6‐trihydroxyacetophenone. For MALDI with these matrixes, linear calibration curves covering wide dynamic ranges were acquired. Performances of these matrixes in various aspects of analyte quantification have been investigated.
Chemoenzymatic Synthesis of Pleiogenone A: An Antiproliferative Trihydroxyalkylcyclohexenone Isolated from Pleiogynium timorense
Authors: Froese Jordan , Overbeeke Cameron , Hudlicky Tomas
Published: March 2016

The first total synthesis of polyhydroxylated cyclohexenone 1, isolated from Pleiogynium timorense and named pleiogenone A, is reported that also serves as a proof of structure and absolute configuration. Enzymatic dihydroxylation of benzoic acid with R. eutrophus B9 provided enantiomerically pure diene diol 6. Elaboration of the carboxylate moiety to the alkyl side chain was followed by singlet oxygen cycloaddition to furnish an endoperoxide whose reduction with thiourea led to cyclitol 19. Several protective operations were required before oxidation and the final extension of the side chain by a Wittig reaction. After final deprotection of the acetonide functionality the desired pleiogenone A (1) was obtained in 14 operations from benzoic acid.
Role of binary solvent and ionic liquid in bitumen recovery from oil sands
Authors: Sui Hong , Zhang Jianqiang , Yuan Yipu , He Lin , Bai Yun , Li Xingang
Published: March 2016

A binary solvent of ethyl acetate and n‐heptane was made and applied together with ionic liquids (ILs, 1‐ethyl‐3‐methyl imidazolium tetrafluoroborate ([Emim]BF4)) to extract bitumen from oil sands at ambient conditions. Results of bottle tests show that the bitumen recovery is highly dependent on the volume ratio of ethyl acetate to n‐heptane. The maximum recovery was obtained at the ethyl acetate‐to‐n‐heptane ratio of 3:6. With external addition of ILs, an additional improvement of ∼10 % of bitumen recovery was observed (from 83 to 93 % at the ethyl acetate‐to‐n‐heptane ratio of 3:6). Based on the intensive investigation of key operational parameters (i.e. ILs‐to‐solvent ratio, agitation time, and conditioning time), a set of recommended extraction conditions were proposed to maximize the bitumen recovery. Further fractionation of the extracted bitumen together with FTIR and SEM detection on the residual solids indicated that ILs addition could increase the dissolution of bitumen fractions into solvents, while reducing the entrapment of fine particles in the solvents. The improvement of bitumen recovery by ILs addition was attributed to the enhancement of the liberation of bitumen components from mineral solids surfaces during oil sands solvent extraction. However, the asphaltenes were observed to be rejected during processing due to their accumulation at the oil‐ILs interface as a film.
The impact of FNAC in the management of salivary gland lesions: Institutional experiences leading to a risk‐based classification scheme
Authors: Rossi Esther Diana , Wong Lawrence Q. , Bizzarro Tommaso , Petrone Gianluigi , Mule Antonio , Fadda Guido , Baloch Zubair M.
Published: March 2016

BACKGROUND

Fine‐needle aspiration cytology (FNAC) has proven its value as an essential step in the diagnosis of salivary gland lesions. Although the majority of salivary gland lesions, especially those that are common and benign, can be diagnosed with ease on FNAC, limited cellularity and morphologic lesion heterogeneity can pose diagnostic challenges and lead to false‐positive and false‐negative diagnoses. This study presents the institutional experience of FNAC of salivary gland lesions from 2 academic centers.

METHODS

A retrospective analysis was conducted on 1729 salivary gland FNAC specimens that were diagnosed over an 8‐year period from January 2008 to March 2015. All samples were processed either with liquid‐based cytology alone or in combination with air‐dried, Diff‐Quik–stained or alcohol‐fixed, Papanicolaou‐stained smears.

RESULTS

Surgical excision was performed in 709 of 1749 FNACs (41%) that were diagnosed as nondiagnostic/inadequate (n = 29), benign (n = 111), neoplasm (n = 453), atypical (n = 15), suspicious for malignancy (n = 28), and malignant (n = 73). The overall concordance between cytologic and histologic diagnoses was 92.2%, with 91.8% concordance in the benign category and 89.5% concordance in cases diagnosed as suspicious for malignancy and malignant. The most frequent benign and malignant lesions were pleomorphic adenoma and squamous cell carcinoma, respectively. There were 46 false‐negative and 13 false‐positive results, leading to an overall specificity of 97.6% and diagnostic accuracy of 91.3%.

CONCLUSIONS

FNAC is a reliable diagnostic modality for the diagnosis and management of salivary gland lesions based on its high specificity and diagnostic accuracy. Cancer Cytopathol 2016;124:388–96. © 2016 American Cancer Society.
Direct evidence of allele equivalency at the Dlx5/6 locus
Authors: Bendall Andrew J.
Published: March 2016

The retention of paralogous regulatory genes is a vertebrate hallmark and likely underpinned vertebrate origins. Dlx genes belong to a family of paralogous transcription factors whose evolutionary history of gene expansion and divergence is apparent from the gene synteny, shared exon–intron structure, and coding sequence homology found in extant vertebrate genomes. Dlx genes are expressed in a nested combination within the first pharyngeal arch and knockout studies in mice clearly point to a “Dlx code” that operates to define maxillary and mandibular position in the first arch. The nature of that code is not yet clear; an important goal for understanding Dlx gene function in both patterning and differentiation lies in distinguishing functional inputs that are paralog‐specific (a qualitative model) versus Dlx family‐generic (a quantitative model) and, in the latter case, the relative contribution made by each paralog. Here, multiple developmental deficiencies were identified in derivatives of the first pharyngeal arch in neonatal Dlx5/6+/− mice that resembled those seen in either paralog‐specific null mutants. These data clearly demonstrate a substantial degree of allele equivalency and support a quantitative model of Dlx function during craniofacial morphogenesis. genesis 54:272–276, 2016. © 2016 Wiley Periodicals, Inc.
The Applications of Nano‐Hetero‐Junction in Optical and Thermal ­Catalysis
Authors: Liao Fenglin , Lo Benedict T. W. , Tsang Edman
Published: March 2016

Semiconductors, metal oxides in particular, are usually regarded as key components in most industrial catalysts. It has been reported that the band structures of semiconductors can significantly influence their catalytic properties. As one of the most effective methods for tuning the band structure of semiconductors, the establishment of nano‐hetero‐junctions in catalysts is attracting increasing attention due to the use of rational design and the facile synthesis procedure. This Microreview covers the applications of nano‐hetero‐junctions in both photocatalytic and traditional thermal catalytic reactions. The applications of these reactions range from removal of pollutants to renewable energy production to new chemical synthesis routes, all of which are closely knitted into our daily lives. In photocatalysis, improvement is mainly attributed to the separation of photogenerated electrons and holes, which prolongs their lifetimes and eventually allows the occurrence of chemical reactions with adsorbed substrate molecules. Our research group were amongst the first to apply this concept in the design of metal/metal oxide catalysts in traditional thermal catalysis. It has been found that the establishment of electronic nano‐hetero‐junctions in support materials with use of two semiconducting metal oxides of different energy levels influences the catalytic properties of the dispersed metal particles from two perspectives: (i) the potential energy upon excitation, created by the charge separation on semiconducting oxide support in proximity to the overlying metal particles, and (ii) under H2, the accumulated electrons on one semiconducting oxide support can facilitate direct reduction of metal cations in this support to metal atoms, while the accumulated holes (activated oxygen) on the other semiconducting oxide are relaxed by water formation through hydrogen oxidation. The metallic atoms from the support surface thus act as modifiers to the primary metal particles through the formation of a bimetallic phase. As a result, the electronic configuration of the supported metal particles can be modified in a subtle manner that consequently influences the catalytic performance. It is believed that this concept of designing nano‐hetero‐junctions should empower scientists to approach new catalytic reactions in a systematic manner, allowing fine‐tuning of catalysts with superior performance.
Functional Dimming of Pincer‐Shaped Bibenzimidazole‐Ruthenium(II) Complexes with Improved Anion‐Sensitive Luminescence
Authors: Sorsche Dieter , Rommel Sebastian A. , Rau Sven
Published: March 2016

Three 2,2′‐bibenzimidazole‐bis(4,4′‐di‐tert‐butyl‐2,2′‐bipyridine)ruthenium(II) complexes are presented and characterized with respect to their photophysical and structural properties. 4,4′,5,5′‐Tetramethyl‐2,2′‐bibenzimidazole (L0), 4,4′‐di(p‐anisyl)‐2,2′‐bibenzimidazole (L1), and the ruthenium complexes K0 and K1 have been reported previously. The new complex K2 contains the structurally confined ligand 4,4′‐di(o,o′‐dimethyl‐p‐anisyl)‐2,2′‐bibenzimidazole. Owing to substitution at the 4,4′‐positions of the bibenzimidazole ligands, complexes K1 and K2 have pincer‐like geometries, as shown by 1H NMR spectroscopy and XRD studies. The emission intensities of these complexes are dimmed compared with that of K0, whereas titration experiments with tetrabutylammonium (TBA) salts of fluoride, chloride, bromide, and iodide show strongly enhanced sensitivity to hydrogen bonding with chloride and bromide ions, which increases the emission intensity to ca. 300 % of the original value, and they eventually outperform K0. With regard to the luminescence sensitivities, K1 and K2 set a new benchmark among 2,2′‐biimidazole ruthenium(II) colorimetric halide sensors.
Copper(I) Complexes of Naphthyl‐Substituted Fluorinated Trispyrazolylborate Ligands with Ethene and Carbon Monoxide
Authors: van Dijkman Thomas F. , Siegler Maxime A. , Bouwman Elisabeth
Published: March 2016

Four CuI complexes of the two new hydridotrispyrazolylborate ligands hydridotris[3‐trifluoromethyl‐5‐(1‐naphthyl)pyrazol‐1‐yl]borate (= [TpCF3,1Nt]–) and hydridotris[3‐trifluoromethyl‐5‐(2‐naphthyl)pyrazol‐1‐yl]borate (= [TpCF3,2Nt]–) have been synthesized by reaction of the sodium salts of the ligands with CuI under either ethene or carbon monoxide atmosphere. Single crystal X‐ray diffraction analyses yielded the molecular structures of the three compounds [Na2(TpCF3,1Nt)2(µ‐acetone)2], [Cu(TpCF3,1Nt)(C2H4)] and [Cu(TpCF3,2Nt)(C2H4)]. The CuI ions are in approximate tetrahedral geometries comprising the three nitrogen donors of the tridentate ligand and the η2‐coordinated ethene ligands. The sodium ion in [Na2(TpCF3,1Nt)2(µ‐acetone)2] is found in a distorted octahedral coordination geometry formed by three N‐donors of the facially coordinating tridentate ligand, two O‐donors of bridging acetone ligands and a fluoride of a bridging –CF3 group with a particularly short Na···F distance. The chemical shifts of the ethene ligands in [Cu(TpCF3,1Nt)(C2H4)] and [Cu(TpCF3,2Nt)(C2H4)] are 5.00 ppm and 4.96 ppm respectively on 1H‐NMR and 85.9 ppm and 85.8 ppm on 13C‐NMR spectroscopy. The CO stretching frequencies in the IR spectra of [Cu(TpCF3,1Nt)(CO)] and [Cu(TpCF3,2Nt)(CO)] are found at 2103 and 2109 cm–1, respectively.
The in‐capillary DPPH‐capillary electrophoresis‐the diode array detector combined with reversed‐electrode polarity stacking mode for screening and quantifying major antioxidants in Cuscuta chinensis Lam
Authors: Liu Jiao , Tian Ji , Li Jin , Azietaku John Teye , Zhang Bo‐li , Gao Xiu‐mei , Chang Yan‐xu
Published: March 2016

An in‐capillary 2, 2‐diphenyl‐1‐picrylhydrazyl (DPPH)‐CE‐the DAD (in‐capillary DPPH‐CE‐DAD) combined with reversed‐electrode polarity stacking mode has been developed to screen and quantify the active antioxidant components of Cuscuta chinensis Lam. The operation parameters were optimized with regard to the pH and concentration of buffer solution, SDS, β‐CDs, organic modifier, as well as separation voltage and temperature. Six antioxidants including chlorogenic acid, p‐coumaric acid, rutin, hyperin, isoquercitrin, and astragalin were screened and the total antioxidant activity of the complex matrix was successfully evaluated based on the decreased peak area of DPPH by the established DPPH‐CE‐DAD method. Sensitivity was enhanced under reversed‐electrode polarity stacking mode and 10‐ to 31‐fold of magnitude improvement in detection sensitivity for each analyte was attained. The results demonstrated that the newly established in‐capillary DPPH‐CE‐DAD method combined with reversed‐electrode polarity stacking mode could integrate sample concentration, the oxidizing reaction, separation, and detection into one capillary to fully automate the system. It was considered a suitable technique for the separation, screening, and determination of trace antioxidants in natural products.
LC–MS/MS of permethylated N‐glycans derived from model and human blood serum glycoproteins
Authors: Hu Yunli , Shihab Tarek , Zhou Shiyue , Wooding Kerry , Mechref Yehia
Published: March 2016

LC–MS/MS is one of the most powerful tools for N‐glycan structure elucidation; however, it is still challenging to identify some glycan structures with low abundance. In this study, we investigated the chromatographic behavior of permethylated N‐glycans. The relationship between retention times versus molecular weight of dextran, dextrin, and model glycans was investigated. Also, the nonpolar surface area of glycans was calculated and compared to their experimental retention times. Both retention time and nonpolar surface area trends are similar when the intermolecular interaction is included in the calculation. Moreover, retention time corresponds to glycan types and branch types. The N‐glycans analysis model, which combines high mass accuracy and retention time, was applied to confirm serum N‐glycans. In total, there were 78 N‐glycan compositions identified. A linear relationship between retention times and molecular weights were observed for each subgroup of glycan structures, for example, R2 value for complex N‐glycans was determined to be > 0.98. Moreover, the retention time could be further applied to distinguish between structural isomers as well as linkage isomers. MS/MS data were used to confirm the structural isomers.
LC‐MS/MS analysis of permethylated free oligosaccharides and N‐glycans derived from human, bovine, and goat milk samples
Authors: Dong Xue , Zhou Shiyue , Mechref Yehia
Published: March 2016

Oligosaccharides in milk not only provide nutrition to the infants but also have significant immune biofunctions such as inhibition of pathogen binding to the host cell. The main component in milk oligosaccharides is free oligosaccharides. Since the proteins in milk are highly glycosylated, N‐glycans in milk also play an import role. In this study, we investigated the permethylated free oligosaccharides and N‐glycans extracted from bovine, goat, and human milks using LC‐MS/MS. Quantitation profiles of free oligosaccharides and N‐glycans were reported. The number of free oligosaccharides observed in bovine, goat, and human milk samples (without isomeric consideration) were 11, 8, and 11, respectively. Human milk had more complex free oligosaccharides structures than the other two milk samples. Totally 58, 21, and 43 N‐glycan structures (without isomeric consideration) were associated with whey proteins extracted from bovine, goat, and human milk samples, respectively. Bovine milk free oligosaccharides and N‐glycans from whey proteins were highly sialylated and to a lesser extend fucosylated. Goat and human milk free oligosaccharides and N‐glycans from whey proteins were both highly fucosylated. Also, the isomeric glycans in milk samples were determined by porous graphitic carbon LC at elevated temperatures. For example, separation of human milk free oligosaccharide Gal‐GlcNAc‐(Fuc)‐Gal‐Glc and Gal‐GlcNAc‐Gal‐Glc‐Fuc isomers was achieved using porous graphitic carbon column. Permethylation of the glycan structures facilitated the interpretation of MS/MS. For example, internal cleavage and glycosidic bond cleavage are readily distinguished in the tandem mass spectra of permethylated glycans. This feature resulted in the identification of several isomers.
Glycosylation and other PTMs alterations in neurodegenerative diseases: Current status and future role in neurotrauma
Authors: Abou‐Abbass Hussein , Abou‐El‐Hassan Hadi , Bahmad Hisham , Zibara Kazem , Zebian Abir , Youssef Rabab , Ismail Joy , Zhu Rui , Zhou Shiyue , Dong Xue , Nasser Mayse , Bahmad Marwan , Darwish Hala , Mechref Yehia , Kobeissy Firas
Published: March 2016

Traumatic brain injuries (TBIs) present a chief public health threat affecting nations worldwide. As numbers of patients afflicted by TBI are expected to rise, the necessity to increase our understanding of the pathophysiological mechanism(s) as a result of TBI mounts. TBI is known to augment the risk of developing a number of neurodegenerative diseases (NDs) such as Alzheimer's disease (AD) and Parkinson's disease (PD). Hence, it is rational to assume that a common mechanistic ground links the pathophysiology of NDs to that of TBIs. Through this review, we aim to identify the protein–protein interactions, differential proteins expression, and PTMs, mainly glycosylation, that are involved in the pathogenesis of both ND and TBI. OVID and PubMed have been rigorously searched to identify studies that utilized advanced proteomic platforms (MS based) and systems biology tools to unfold the mechanism(s) behind ND in an attempt to unveil the mysterious biological processes that occur postinjury. Various PTMs have been found to be common between TBI and AD, whereas no similarities have been found between TBI and PD. Phosphorylated tau protein, glycosylated amyloid precursor protein, and many other modifications appear to be common in both TBI and AD. PTMs, differential protein profiles, and altered biological pathways appear to have critical roles in ND processes by interfering with their pathological condition in a manner similar to TBI. Advancement in glycoproteomic studies pertaining to ND and TBI is urgently needed in order to develop better diagnostic tools, therapies, and more favorable prognoses.
Metal cation control of electroosmotic flow magnitude in phospholipid‐coated capillaries
Authors: Wells Shane S. , De La Toba Eduardo , Harrison Christopher R.
Published: March 2016

CZE has become widespread for the separation and analysis of biomolecules such as proteins and peptides, due to factors such as, the speed of the separations, low sample volume, and high resolution associated with the technique. However, the separation of biomolecules by CZE does present a significant challenge due to the electrostatic attraction and adsorption of cationic, or cation containing, biomolecules to the capillary surface. To that end numerous methods have been developed to passivate, or protect the surface, in order to prevent the adsorption of analytes. Yet, in the process of protecting the capillary surface, the potential for further modification of the EOF, a factor crucial to effective analyte resolution, is greatly diminished. In seeking to overcome this limitation we have explored the potential of incorporating a range of metal cations into a phospholipid bilayer capillary coating. It has previously been established that the inclusion of calcium into the separation buffer with a phospholipid coating will reverse the EOF in the capillary. Here, we present our investigation of a broader range of metal cations included in the separation buffer (Ca2+, Mg2+, Co2+, Ni2+, Sr2+, Ba2+, and Ce3+) revealing that the choice of metal cation can drastically influence the EOF, with observed values between −3.80 × 10−4 and −5.74 × 10−5 cm2/V·s.