bluuebunny/crossref_metadata_2025 huggingface dataset:
Combined effect of graphene oxide and MWCNTs on microwave absorbing performance of epoxy composites
Authors: Arooj Yusra , Zhao Yan , Han Xiao , Bao Tianjiao , Wang Yan
Published: March 2015

Currently, carbon nanotube (CNT) ‐based composites have been considered as microwave absorbers because of the fascinating properties of CNTs. In this work, multi‐walled CNTs (MWCNTs) and graphene oxide (GO) ‐based epoxy composites (i.e. MWCNT/EPr and GO‐MWCNT/EPr), with sample thickness of 2 mm, were prepared to study microwave absorbing properties in the frequency band of 8–18 GHz. Uniform dispersion of MWCNTs in the organic solvent and polymer matrix was achieved by preparation of GO. The test for electromagnetic parameters, i.e. complex permittivity and the permeability of the samples, was carried out with vector network analyzer (VNA) using reflection‐transmission waveguides. Results showed that GO‐MWCNT/EPr composites have better absorption capability than MWCNT/EPr composites. The improved reflection loss for the composites with 0.4 wt% and 0.6 wt% of GO (out of total filler loading 6 wt%) were −14.32 dB and −14.29 dB, respectively. The improvement in reflection loss and absorption bandwidth for GO‐MWCNTs composites suggested that MA features are synergistically effected by GO and MWCNTs. Further skin depth and shielding effectiveness terms are studied to observe overall mechanism of electromagnetic (EM) shielding which showed that multiple reflections also play a role in EM shielding. Copyright © 2015 John Wiley & Sons, Ltd.
Mechanical and barrier properties of ternary nanocomposite films based on polycarbonate/amorphous polyamide blends modified with a nanoclay
Authors: Santamaría Pablo , González Imanol , Eguiazábal José I.
Published: March 2015

Ternary polycarbonate (PC)/amorphous polyamide–nanoclay (naPA) nanocomposite (PC/naPA) films were obtained by melt mixing and drawing, and the effects of the naPA content and the draw ratio (DR) on the structure, morphology and mechanical and barrier properties were studied. Despite the presence of nanoclay, the films exhibited a negligible roughness and the excellent optical properties of PC and amorphous polyamide (aPA). The dispersed naPA phase was pure and small, indicating compatibility. The naPA did not hinder the drawing ability of PC. At low DRs the dispersed phase was elongated and oriented along the machine direction (extrusion flow direction), but at high DRs, it fibrillated due to the higher non‐isothermal elongational flow induced by drawing. The laminar structure of the nanoclay allowed the films to be reinforced both in the machine and the transverse directions. The oxygen permeability of PC was reduced by 42% in the nanocomposite with 25% of naPA, and dropped further with the DR, which is attributed to the increased tortuosity of the oxygen path induced by fibrillation. Copyright © 2015 John Wiley & Sons, Ltd.
Some new perspectives of anionic polyamide 6 (APA 6) synthesis
Authors: Russo Saverio , Maniscalco Sabrina , Ricco Laura
Published: March 2015

The anionic polymerization of ε‐caprolactam in the bulk is now enriched by a new member belonging to the family of very fast activators, represented by blocked (triethoxysilyl)propylisocyanate. The activator is able to allow polymerization completion in a few tens of seconds in quasi‐adiabatic conditions starting from ca. 150°C. The most relevant and unexpected feature of its role in ε‐caprolactam activated anionic polymerization arises from the observation that the resultant APA 6 is extensively crosslinked in situ up to ca. 80% despite the isocyanate monofunctionality of the activator. Comparison with the behavior of a commercial trifunctional activator/crosslinker is carried out and possible explanation of (triethoxysilyl)propylisocyanate role as a crosslinker is put forward. Optimization of the procedure to properly evaluate the degree of APA 6 crosslinking in comparison with a literature method is established. Other tested silane derivatives do not behave similarly in the same experimental conditions of synthesis. The strong adhesion, due to the triethoxysilyl group, to glass fibers introduced in the polymerizing medium is a relevant additional advantage of the quoted activator. Possible industrial applications can be foreseen. Copyright © 2015 John Wiley & Sons, Ltd.
Effect of diisocyanates and chain extenders on the physicochemical properties and morphology of multicomponent segmented polyurethanes based on poly(l‐lactide), poly(ethylene glycol) and poly(trimethylene carbonate)
Authors: Trinca Rafael Bergamo , Felisberti Maria Isabel
Published: March 2015

Multicomponent segmented polyurethanes (SPUs) based on poly(ethylene glycol), poly(l‐lactide) and poly(trimethylene carbonate) as macrodiols, 2,4‐toluene diisocyanate (2,4‐TDI) or 1,6‐hexane diisocyanate (HDI) as diisocyanate, and 1,4‐butanediol (BDO) or 2,2‐bis(hydroxymethyl)propionic acid (DMPA) as chain extenders were synthesized. The molecular, thermal, dynamic mechanical and morphological features of this set of uncrosslinked polyurethanes are characterized using 1H NMR, gel permeation chromatography, differential scanning calorimetry, dynamic mechanical thermal analysis (DMTA) and atomic force microscopy techniques. The lower reaction rate of HDI in comparison with 2,4‐TDI allows for better control of the SPU compositions, so that the intrinsic properties of each block can be better combined and modulated. HDI‐based SPUs are semi‐crystalline, while those based on 2,4‐TDI are amorphous, affecting the mechanical properties of these polyurethanes. All SPUs are heterogeneous, presenting morphologies of a disperse phase in a matrix which varies with the macrodiol ratios as well as with the nature of the diisocyanate and chain extender (a finer dispersion of the disperse phase is observed for SPUs of HDI and BDO). DMTA results indicate that the phases are complex mixtures of the different blocks with at least one rich in PLLA. The PEG content is shown to be the most important factor influencing the water sorption capability, while the incorporation of hindering carboxylic acid groups by the use of DMPA allows the water uptake of SPUs to be controlled by the solution pH. All SPUs show a significant loss of molar mass in hydrolytic degradation experiments and, in general, the PLLA‐rich SPUs are more susceptible to degradation. © 2015 Society of Chemical Industry
Alterations in the proteome of the respiratory tract in response to single and multiple exposures to naphthalene
Authors: Kültz Dietmar , Li Johnathon , Sacchi Romina , Morin Dexter , Buckpitt Alan , Van Winkle Laura
Published: March 2015

Protein adduction is considered to be critical to the loss of cellular homeostasis associated with environmental chemicals undergoing metabolic activation. Despite considerable effort, our understanding of the key proteins mediating the pathologic consequences from protein modification by electrophiles is incomplete. This work focused on naphthalene (NA) induced acute injury of respiratory epithelial cells and tolerance which arises after multiple toxicant doses to define the initial cellular proteomic response and later protective actions related to tolerance. Airways and nasal olfactory epithelium from mice exposed to 15 ppm NA either for 4 h (acute) or for 4 h/day × 7 days (tolerant) were used for label‐free protein quantitation by LC/MS/MS. Cytochrome P450 2F2 and secretoglobin 1A1 are decreased dramatically in airways of mice exposed for 4 h, a finding consistent with the fact that CYPs are localized primarily in Clara cells. A number of heat shock proteins and protein disulfide isomerases, which had previously been identified as adduct targets for reactive metabolites from several lung toxicants, were upregulated in airways but not olfactory epithelium of tolerant mice. Protein targets that are upregulated in tolerance may be key players in the pathophysiology associated with reactive metabolite protein adduction. All MS data have been deposited in the ProteomeXchange with identifier PXD000846 (http://proteomecentral.proteomexchange.org/dataset/PXD000846).
Unrestricted modification search reveals lysine methylation as major modification induced by tissue formalin fixation and paraffin embedding
Authors: Zhang Ying , Muller Markus , Xu Bo , Yoshida Yutaka , Horlacher Oliver , Nikitin Frederic , Garessus Samuel , Magdeldin Sameh , Kinoshita Naohiko , Fujinaka Hidehiko , Yaoita Eishin , Hasegawa Miki , Lisacek Frederique , Yamamoto Tadashi
Published: March 2015

Formalin‐fixed paraffin‐embedded (FFPE) tissue is considered as an appropriate alternative to frozen/fresh tissue for proteomic analysis. Here we study formalin‐induced alternations on a proteome‐wide level. We compared LC‐MS/MS data of FFPE and frozen human kidney tissues by two methods. First, clustering analysis revealed that the biological variation is higher than the variation introduced by the two sample processing techniques and clusters formed in accordance with the biological tissue origin and not with the sample preservation method. Second, we combined open modification search and spectral counting to find modifications that are more abundant in FFPE samples compared to frozen samples. This analysis revealed lysine methylation (+14 Da) as the most frequent modification induced by FFPE preservation. We also detected a slight increase in methylene (+12 Da) and methylol (+30 Da) adducts as well as a putative modification of +58 Da, but they contribute less to the overall modification count. Subsequent SEQUEST analysis and X!Tandem searches of different datasets confirmed these trends. However, the modifications due to FFPE sample processing are a minor disturbance affecting 2–6% of all peptide‐spectrum matches and the peptides lists identified in FFPE and frozen tissues are still highly similar.
Parameterization of electrostatic interactions for molecular dynamics simulations of heterocyclic polymers
Authors: Nazarychev Victor M. , Larin Sergey V. , Yakimansky Alexander V. , Lukasheva Natalia V. , Gurtovenko Andrey A. , Gofman Iosif V. , Yudin Vladimir E. , Svetlichnyi Valentin M. , Kenny Jose M. , Lyulin Sergey V.
Published: March 2015

The paper focuses on the problem of electrostatic interactions in molecular dynamics simulations of thermal properties of heterocyclic polymers. The study focuses on three thermoplastic polyimides synthesized on the basis of 1,3‐bis‐(3′,4‐dicarboxyphenoxy)benzene (dianhydride R) and three diamines: 4,4′‐bis‐(4″‐aminophenoxy) diphenylsulfone (diamine BAPS), 4,4′‐bis‐(4″‐aminophenoxy) biphenyl (diamine BAPB), and 4,4′‐bis‐(4''‐aminophenoxy) diphenyloxide (diamine BAPO). In the molecular dynamics simulations these polyimides were described by the Gromos53a5 force field. To parameterize the electrostatic interactions four methods of calculating the partial atomic charges were chosen: B3LYP/6–31G*(Mulliken), AM1(Mulliken), HF/6–31G*(Mulliken), and HF/6–31G*(ChelpG). As our parameterization is targeted to reproduce thermal properties of the thermoplastic polyimides, the choice of proper partial charges was finalized on a basis of the closest match between computational and experimental data for the thermal expansion coefficients of the polyimides below glass transition temperatures. Our finding clearly show that the best agreement with experimental data is achieved with the Mulliken partial atomic charges calculated by the Hartree‐Fock method with 6–31G* basis set. Furthermore, in addition to the thermal expansion coefficients this set of partial atomic charges predicts an experimentally observed relationship between glass transition temperatures of the three polyimides under study:
. A mechanism behind the change in thermal properties upon the change in the chemical structure in considered polyimides may be related to an additional spatial ordering of sulfone groups due to dipole‐dipole interactions. Overall, the modified force‐field is proved to be suitable for accurate prediction of thermal properties of thermoplastic polyimides and can serve as a basis for building up atomistic theoretical models for describing other heterocyclic polymers in bulk. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 912–923
A Simple Technique to Improve Contractile Effect of Cold Plasma Jet on Acute Mouse Wound by Dropping Water
Authors: Nasruddin  , Nakajima Yukari , Mukai Kanae , Komatsu Emi , Rahayu Heni Setyowati Esti , Nur Muhammad , Ishijima Tatsuo , Enomoto Hiroshi , Uesugi Yoshihiko , Sugama Junko , Nakatani Toshio
Published: March 2015

A simple technique is tested to improve the contractile effect of a cold plasma jet on acute wounds of mice. Distilled water on the order of microliters is dropped onto wounds before treatment. To assess the fate of the water, an infrared thermal imager is applied. To evaluate the healing effect, macroscopic and immunohistological studies are conducted. Regarding the wound contractile effect, we show that combination treatment of plasma with dropped water seemed to have a greater effect than plasma treatment alone. Plasma may modify the wound surface through such water, chemically and physically. The histological stiffness of the wound surface during maturation and remodeling, however, may also influence the fate of the water during treatment.
Eslicarbazepine acetate for the treatment of focal epilepsy: an update on its proposed mechanisms of action
Authors: Soares‐da‐Silva Patrício , Pires Nuno , Bonifácio Maria João , Loureiro Ana I. , Palma Nuno , Wright Lyndon C.
Published: March 2015

Eslicarbazepine acetate (ESL) is a once daily antiepileptic drug (AED) approved by the European Medicines Agency (EMA), the Food and Drug Administration (FDA) and Health Canada as an adjunctive therapy in adults with partial‐onset seizures (POS). In humans and in relevant animal laboratory species,ESLundergoes extensive first pass hydrolysis to its major active metabolite eslicarbazepine that represents ~95% of circulating active moieties.ESLand eslicarbazepine showed anticonvulsant activity in animal models.ESLmay not only suppress seizure activity but may also inhibit the generation of a hyperexcitable network. Data reviewed here suggest thatESLand eslicarbazepine demonstrated the following in animal models: (1) the selectivity of interaction with the inactive state of the voltage‐gated sodium channel (VGSC), (2) reduction inVGSCavailability through enhancement of slow inactivation, instead of alteration of fast inactivation ofVGSC, (3) the failure to cause a paradoxical upregulation of persistent Na+current (INaP), and (4) the reduction in firing frequencies of excitatory neurons in dissociated hippocampal cells from patients with epilepsy who were pharmacoresistant to carbamazepine (CBZ). In addition, eslicarbazepine effectively inhibited high‐ and low‐affinity hCaV3.2 inward currents with greater affinity thanCBZ. These preclinical findings may suggest the potential for antiepileptogenic effects; furthermore, the lack of effect uponKV7.2 outward currents may translate into a reduced potential for eslicarbazepine to facilitate repetitive firing.
A novel 2‐decenoic acid thioester ameliorates corticosterone‐induced depression‐ and anxiety‐like behaviors and normalizes reduced hippocampal signal transduction in treated mice
Authors: Shibata Shoyo , Iinuma Munekazu , Soumiya Hitomi , Fukumitsu Hidefumi , Furukawa Yoshiko , Furukawa Shoei
Published: March 2015

We characterized mice administered corticosterone (CORT) at a dose of 20 mg/kg for 3 weeks to determine their suitability as a model of mood disorders and found that the time immobilized in the tail suspension test was longer and the time spent in the open arms of the elevated plus‐maze test was shorter than those of the vehicle‐treated group, findings demonstrating that chronic CORT induced both depression‐like and anxiety‐like behaviors. Furthermore, the levels of phosphorylated extracellular signal‐regulated kinase (pERK) 1/2 in the hippocampus and cerebral cortex were reduced in the CORT‐treated group. Using this model, we investigated the protective effect of the ester, thioester, and amide compounds of 2‐decenoic acid derivatives (termed compounds A, B, and C, respectively). The potency of the protective activity against the CORT‐induced depression‐like or anxiety‐like behaviors and the reduction in pERK1/2 level were found to be in the following order: compound B > compound C > compound A. Therefore, we further investigated the therapeutic activity of only compound B, and its effect on depression‐like behavior was observed after oral administration for 1 or 2 weeks, and its effect on anxiety‐like behavior was observed after oral administration for 3 weeks. The ratios of phosphorylated ERK1/2, Akt, and cAMP‐response element‐binding protein to their respective nonphosphorylated forms were smaller in the CORT‐treated group than in the vehicle‐treated group; however, subsequent treatment with compound B at either 0.3 or 1.5 mg/kg significantly ameliorated this reduction. Compound B appeared to elicit intracellular signaling, similar to that elicited by brain‐derived neurotrophic factor, and its mode of action was shown to be novel and different from that of fluvoxamine, a currently prescribed drug for mood disorders.
Migrant Street Vendors in Urban China and the Social Production of Public Space
Authors: Flock Ryanne , Breitung Werner
Published: March 2015

This article focuses on the dynamics between migrant street vendors and public security forces and the complex social production of urban public space in Guangzhou. As an answer to daily contestation of public order, security agencies reluctantly open flexible windows of business opportunities to hawkers. Zones and periods of control, ‘soft’ approaches, and categories of ethnic belonging influence everyday governance and accessibility of public space. This results in a transient public space, fluid and continuously changing, which offers a new perspective on openness and functioning of public space in urban China. Copyright © 2015 John Wiley & Sons, Ltd.
Young Germans in England Visiting Germany: Translocal Subjectivities and Ambivalent Views of ‘Home’
Authors: Mueller Dorothea
Published: March 2015

Using the case of young German professionals living in England, this paper argues that visiting friends and relatives (VFR) is dominated by complexity and ambivalence, even in a seemingly straightforward migration. The geographical proximity between the migration destination and origin in the case study both creates and reveals this complexity and ambivalence through the potential of frequent visits in both directions. The research is based on one year of participant observation amongst young Germans in London, as well as 39 formal, in‐depth interviews with participants aged 23–42. All participants, both interviewees and others encountered during fieldwork, engaged in regular visits to Germany as well as receiving visitors from Germany, but displayed different, complex time‐space patterns of VFR. Bi‐local migrants were mostly recently arrived straight from their home region in Germany; the bi‐locality of their VFR mobilities was defined by their pattern of visiting, and being visited by, friends and relatives in their region of origin only. Multi‐local migrants had more geographically dispersed patterns of VFR behaviour, reflecting their more complex mobility histories, both internally within Germany and internationally, before moving to England. Finally, settled migrants had been in England a long time, often since school or university, and planned to stay; hence their VFR behaviour, either bi‐locally or multi‐locally defined, was less intense. Within this threefold categorisation, the paper explores the complex emotionality of VFR, including feelings of guilt and ambivalence, mainly towards parents and friends. By highlighting the complexity within one migration, it also adds more nuance to recent work of attempted typologies of VFR in migration. Theoretically, the analysis is located within the field of transnational urbanism and its more specific working concept of translocal subjectivities, which provides the operational setting for analysing migrants' feelings, tensions, and conflicts over their VFR activities and responsibilities. Copyright © 2015 John Wiley & Sons, Ltd.
Short‐Term Visits and Tongan Livelihoods: Enterprise and Transnational Exchange
Authors: Cave Jenny , Koloto 'Ana Hau'alofa'ia
Published: March 2015

A culture of migration and return is now part of everyday life in the Kingdom of Tonga, and transnational exchange relationships are crucial to the country's economy. Despite research on the impacts of remittances and other transnational exchange activities on livelihoods in Tonga and in migrant host countries, there has been little research on the interwoven dependencies and relationships amongst home, host, local, and diasporan nodes or the impact of short‐term visits in both directions. This paper explores dynamic processes within the agency of family‐linked economic and social practices of migrants and their descendants in host countries as well as their homelands. These activities are theorised within transnational contexts ‘from below’ (micro), ‘above’ (macro), ‘middling’ (meso), and ‘from above’ (macro) levels. The methodology, grounded in Pacific and Western ontologies, co‐creatively analyses the exchange and enterprise activities of families on a remote island of Tonga with high out‐migration, compared with their relatives in Auckland, New Zealand. Key findings are that short‐term visiting ensures the survival of a range of economic, social, and cultural activities that are critically important for ‘being Tongan’ in the different diasporan contexts. The originality of the research lies in retheorising enterprise alternatives for transnational Tongans, development of a Pacific‐framed view of transnational enterprise, and method that captures exchange complexities. The analysis fills a gap in knowledge regarding the impact of short visits on diasporan livelihoods, with implications for labour policy in home and diasporan locations to encourage youth to stay longer and older people to return sooner. Copyright © 2015 John Wiley & Sons, Ltd.
Advances in III‐nitride semiconductor microdisk lasers
Authors: Zhang Yiyun , Zhang Xuhui , Li Kwai Hei , Cheung Yuk Fai , Feng Cong , Choi Hoi Wai
Published: March 2015

This paper reviews the recent progress in the design and fabrication strategies of III‐nitride semiconductor microdisk lasers on sapphire or Si substrates. Involving more accurate lithography methods in the fabrication boosts quality factors (Q‐factors) due to the improved optical confinement of whispering‐gallery modes (WGMs) at the rim of the microdisks with smooth sidewalls and perfect circularity. Quantum dots (QDs) as gain medium within the microdisks are investigated and promising for the demonstration of micro‐lasers with super‐high Q‐factors and ultra‐low thresholds. And these QD‐cavity systems are also facilitating the research of cavity quantum electrodynamics (QED) in the strong coupling regime and cavity‐enhanced single photon emission (SPE) for quantum computing. In this paper, we also report successful fabrication of transferred GaN free‐standing microdisks with InGaN quantum wells (QWs) on conductive substrates, which achieves a significant step forward to realize electrically pumped high‐quality microdisk lasers on target substrates. Strategies of applying flexible transparent electrodes such as graphene and metallic nanowires are potential effective solutions for realizing current‐injection of nitride‐based microdisks.
Dynamic response of sandwich panels with auxetic cores
Authors: Strek Tomasz , Jopek Hubert , Nienartowicz Maria
Published: March 2015

Effective properties and dynamic response of a sandwich panel made of two face sheets and auxetic core are analyzed in this study by computer simulations. The inner composite layer is made of a cellular auxetic structure immersed in a filler material of a given Poisson's ratio (filler material fills the voids in structure). Each cell is composed of an auxetic structure (re‐entrant honeycomb or rotating square), i.e., exhibiting negative Poisson's ratio without any filler. Influence of filler material on the effective properties of the sandwich panel is investigated. The proposed structure shows interesting structural characteristics and dynamic properties. Our results clearly show that it is possible to create auxetic sandwich panels made of two solid materials with positive Poisson's ratio. This is even possible if the filler material is nearly incompressible, but can move in out‐of‐plane direction. Moreover, effective Young's modulus of such sandwich panels becomes very large if the Poisson's ratio of the filler material tends to −1.
Power dependence of unusual bands in photoluminescence spectra of AlGaN/GaN heterostructures
Authors: Osinnykh I. V. , Zhuravlev K. S. , Malin T. V.
Published: March 2015

AlGaN/GaN heterostructures with a two‐dimensional electron gas (2DEG) grown by metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) techniques were investigated by photoluminescence (PL) spectroscopy. Series of PL bands located below the donor bound excitons band have been observed for a high quality MOCVD sample. Two of these PL bands peaked at ħωmax=3.446 and ħωmax=3.423 eV have been observed at both continuous and pulse excitation and connected with the recombination of 2DEG localized at the first and the second levels in the quantum well with free holes. The PL band at ħωmax=3.36 eV may be attributed to recombination of the 2DEG electrons with holes located at acceptors. Band at ħωmax=3.41 eV is not connected with 2DEG because of this band didn’t disappear after etching of the AlGaN layer and this band was observed in all samples. An intensity of all these four PL bands increased superlinearly with rise of the excitation power. The exponents for the Y bands more than 2, while the exponent for the excitonic band is about 1.5 at T=5 K. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Minority carrier diffusion length in AlxGa1‐xN (x = 0.1) grown by ammonia molecular beam epitaxy
Authors: Malin Timur , Gilinsky Alexander , Mansurov Vladimir , Protasov Dmitriy , Yakimov Eugeny , Zhuravlev Konstantin
Published: March 2015

The room‐temperature minority carrier diffusion length in n ‐Al0.1Ga0.9N grown by ammonia molecular beam epitaxy on (0001) sapphire for photodetector applications has been investigated. The measurements were performed using the spectral dependence of the photocurrent detected by the built‐in p‐n ‐junction on thinner layer samples, and by the electron beam induced current technique on films of up to 2 µm in thickness. The results show that the hole diffusion length in n ‐AlGaN films amounts to 120‐150 nm, which is by 3‐4 times larger than that in GaN films grown under similar growth conditions. The thicker films do not show a considerable improvement in the hole diffusion length value. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of transparent CuxZnyS/ZnS heterojunction diodes by photochemical deposition
Authors: Ichimura Masaya , Maeda Yosuke
Published: March 2015

A CuxZnyS/ZnS transparent pn heterostructure was successfully fabricated by the photochemical deposition (PCD) from aqueous solutions. In PCD, the substrate was immersed in the solution to a depth of about 2‐3 mm from solution surface, and irradiated with the light of an ultra‐high‐pressure mercury arc‐lamp through a lens. The growth solution of CuxZnyS contained 5 mM CuSO4, 1 mM ZnSO4, 600 mM Na2S2O3, and 3 mM Na2SO3. The growth solution of ZnS contained 1 mM ZnSO4, 600 mM Na2S2O3, and 3 mM Na2SO3. p‐type conduction of CuxZnyS and n‐type conduction of ZnS were confirmed by the photoelectrochemical measurement. Both the films had high optical transmission (>70%) in the visible range. The CuxZnyS/annealed‐ZnS heterostructure showed rectification properties and photoresponse to AM1.5 irradiation. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐performance AlGaN/AlN/GaN high electron mobility transistor with broad gate‐to‐source operation voltages
Authors: Tsai Jung‐Hui , Chiang Chung‐Cheng , Wang Fu‐Min
Published: March 2015

In this article, a high‐performance AlGaN/AlN/GaN high electron mobility transistor (HEMT) with broad gate‐to‐source operation voltages is fabricated and demonstrated. The experimental results exhibit a maximum extrinsic transconductance of 94.2 mS/mm at VGS = ‐2.58 V and a threshold voltage of ‐3.68 V at drain output current of 1 mA/mm.The insertion of an AlN interfacial layer can enhance the carrier confinement ability in channel and extend the gate operation voltage to +5 V. Furthermore, the effect of gate recess on device performance is investigated by two‐dimensional simulation. The simulated results show that the AlGaN/AlN/GaN HEMT with gate recess structure has higher equivalent Schottky barrier height, larger electron concentration in channel, larger drain output current and transconductance as compared with the device without gate recess structure. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low‐temperature heteroepitaxial growth of InAlAs layers on ZnSnAs2/InP(001)
Authors: Oomae Hiroto , Suzuki Akiko , Toyota Hideyuki , Nakamura Shin'ichi , Uchitomi Naotaka
Published: March 2015

We studied the epitaxial growth of InAlAs on ZnSnAs2 thin films to establish magnetic heterostructures involving ferromagnetic Mn‐doped ZnSnAs2 (ZnSnAs2:Mn) thin films. These heterostructures were successfully grown at temperatures around 300 °C to maintain room‐temperature ferromagnetism in ZnSnAs2:Mn. Reflection high‐energy electron diffraction, X‐ray diffraction measurements and cross‐sectional transmission electron microscopy revealed that the InAlAs layers were pseudomorphically lattice‐matched with ZnSnAs2, even at the low temperature of 300 °C. We attempted to prepare magnetic quantum well structures from the InAlAs/ZnSnAs2:Mn magnetic multilayer structure. We found that InAlAs layers heteroepitaxially grown on ZnSnAs2 and ferromagnetic ZnSnAs2:Mn films are suitable for preparing InP‐based magnetic semiconductor quantum structures. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electronic structure of BaFeO3 studied by X‐ray spectroscopy
Authors: Mizumaki Masaichiro , Fujii Hitoshi , Yoshii Kenji , Hayashi Naoaki , Saito Takashi , Shimakawa Yuichi , Uozumi Takayuki , Takano Mikio
Published: March 2015

We investigated the electronic structure of BaFeO3 by using HAXPES and XAS measurements and first principle studies. The experimental and theoretical results indicated that BaFeO3 is a negative charge transfer compound. We concluded that the on‐site Coulomb energy and the strong hybridization between Fe‐3d and O‐2p orbitals play a very important role of emergence of negative charge transfer. And we found the new structure in the Fe‐2p XPS spectrum and concluded this structure is originated from non‐local screening. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Deposition of Cl‐doped CdTe polycrystalline films by close‐spaced sublimation
Authors: Okamoto Tamotsu , Takahashi Kohei , Akiba Sho , Yasuda Nao , Tokuda Satoshi , Kishihara Hiroyuki , Ichioka Akina , Doki Takahiro , Sato Toshiyuki
Published: March 2015

The effects of Cl‐doping on the CdTe layers by the close‐spaced sublimation (CSS) deposition were investigated. Cl‐doped CdTe polycrystalline films were deposited on graphite substrates by CSS method using a mixture of CdTe and CdCl2 powder as a source. In X‐ray diffraction (XRD) patterns of the obtained films with various deposition times, many diffraction peaks other than CdTe peaks were observed in the deposition times lower than 10 min. These diffraction peaks were probably due to the formation of chlorides of Cd, Te and C, such as CdCl2, TeCl4, Te3Cl2 and C10Cl8. X‐ray fluorescence (XRF) and secondary ion mass spectrometry (SIMS) analyses revealed that a large amount of chlorine was contained in the films with the deposition times lower than 10 min, and that Cl concentration decreased with increasing the deposition time above 3 min. These results indicate that the films containing the chlorides of Cd, Te and C in addition to CdTe are formed in the initial stage of the CSS deposition using a mixture of CdTe and CdCl2 powder as a source. Cross‐sectional images revealed that the grain size was decreased by the effect of Cl‐doping. Furthermore, current‐voltage (I ‐V) characteristics of the CdTe/graphite structures were measured, and it was found that the resistivity of the Cl‐doped CdTe layer was much higher than that of the undoped CdTe layer. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A mild hydrothermal route to synthesis of CZTS nanoparticle inks for solar cell applications
Authors: Vanalakar S. A. , Agwane G. L. , Gang M. G. , Patil P. S. , Kim J. H. , Kim J. Y.
Published: March 2015

Cu2ZnSnS4 (CZTS) is a promising thin film absorber material for low cost solar cell applications. Its absorption coefficient (∼ 104 cm‐1), crystal structure and band gap energies (∼1.5 eV) are similar to those of Cu(In,Ga)Se2 (CIGS), one of the most studied and flourishing thin film solar cell absorber materials. However, unlike CIGS, which requires the expensive and rare elements; In and Ga, CZTS is composed of reasonably priced and abundant elements like Zn and Sn. In the present investigation, kesterite CZTS nanoparticle inks were obtained by a hydrothermal process using Cu, Zn and Sn chlorides, and Na sulfide. The synthesized CZTS nanoparticles were characterized using optical absorption, X‐ray powder diffraction (XRD), energy dispersive spectroscopy (EDS), micro‐Raman spectroscopy, high‐resolution transmission electron microscopy (HRTEM), and X‐ray photoelectron spectroscopy (XPS). The optical and morphological properties demonstrated that the prepared nanoparticles have strong absorption in 300−550 nm range with band gap energy of 1.55 eV with an average particle size of 20 nm. The X‐ray and micro‐Raman analysis revealed that the synthesized CZTS nanoparticles have the phase pure kesterite structure. We believe that our synthetic method will be helpful for low‐cost and efficient thin film photovoltaic technology. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of supercritical carbon dioxide treatment on the polarons of HCl‐doped polyaniline films
Authors: Fernando J. G. , Vequizo R. M. , Odarve M. K. G. , Sambo B. R. B. , Malaluan R. M. , Malaluan L. A. M.
Published: March 2015

In situ HCl‐doped polyaniline films were synthesized on glass substrates via chemical oxidative polymerization of aniline using ammonium peroxydisulfate as oxidant. The films were treated with supercritical carbon dioxide (SC‐CO2) at 30 MPa and 40 °C for 30 minutes. The physico‐chemical and electrical properties of the films were determined to establish the effect of supercritical carbon dioxide treatment on the polaron structures of polyaniline films. The treatment removed limited number of polarons which affected the properties of polyaniline. The treated films remained conducting despite that the conductance decreased substantially. The treatment enhanced the quinoid character of the films and altered the HOMO‐LUMO transitions. In addition, SC‐CO2 treatment was unable to remove the PANI precipitations adhering on the surface of the films. A mechanism on the effect of SC‐CO2 interaction to HCl‐doped PANI films was proposed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of Cu2ZnSnSe4 thin films by selenization of precursor using Cu2ZnSnSe4 compound for photovoltaic applications
Authors: Nakashima M. , Yamaguchi T. , Kusumoto K. , Yukawa S. , Sasano J. , Izaki M.
Published: March 2015

Cu2ZnSnSe4 ingot was synthesized and then used it and Na2Se powder as evaporation materials to prepare a precursor for selenization process in order to fabricate Cu2ZnSnSe4 thin films for solar cell applications. From EPMA analysis, the Sn content in the thin films was approximately constant with increasing Sn mole ratio and the Se content was under 50 at.% in the first experiment. The Se content in the thin films increased to around 50 at.% by the addition of Se layer in second experiment. XRD study showed that the thin films had a kesterite phase in Cu2ZnSnSe4. The Se layer addition enhanced to grow thin films having a close‐packed structure and columnar grains. Cu2ZnSnSe4 thin film solar cells demonstrated Voc= 282 mV, Isc= 3.00 mA/cm2. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crystallization mechanism of sol‐gel synthesized spinel LiMn2O4
Authors: Kushida K. , Kuriyama K.
Published: March 2015

Crystallization mechanism of sol‐gel synthesized spinel LiMn2O4 is studied by a differential scanning calorimetry (DSC) method. Lithium acetate and manganese acetate are dissolved in methanol in the atomic ratio of 1:2 (Li:Mn) with citric acid as a chelating agent, leading to a sol solution. A Li‐Mn gel precursor is obtained by partly evaporating the sol solution. A large exothermic reaction of the Li‐Mn gel starts at 280 °C, indicating that the combustions of C and H atoms released from the gel occur above 280 °C. After the rise in temperature to 290 °C, the exothermic reaction of the gel continues at the constant temperature of 290 °C, indicating that the rearrangement of Li, Mn and O atoms for the crystallization into the spinel structure mainly occurs at 290 °C. This suggests that annealing the Li‐Mn gel precursor above 290 °C is necessary to obtain spinel LiMn2O4. During the exothermic reaction, Mn atoms released from the gel occupy the octahedral sites in the spinel framework of O, and Li atoms also released are inserted into the tetrahedral sites. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bulk crystal growth and characterization of ZnSnP2 compound semiconductor by flux method
Authors: Nakatsuka Shigeru , Nakamoto Hiroshi , Nose Yoshitaro , Uda Tetsuya , Shirai Yasuharu
Published: March 2015

ZnSnP2 is a promising candidate for solar absorber materials from the viewpoint of high absorption and earth‐abundant constitution elements. In this paper, we fabricated ZnSnP2 crystals by flux method based on the phase diagram of Sn‐ZnP2 pseudo‐binary system and investigated their properties for an application to photovoltaics. The crystal growth experiments with the cooling rate of 0.7 and 12 °C/h were carried out and we successfully obtained ZnSnP2 crystals with the diameter of 8mm and the thickness of a few mm by a slow cooling rate. The structure of grown crystals studied by X‐ray diffraction was indicated to be chalcopyrite‐type ZnSnP2. In addition, the decrease of the degree of order was observed with the increase of cooling rate. The lattice constants of a and c axes are 5.649 and 11.295 Å, respectively. The composition of grown crystals is a near stoichiometric ratio of ZnSnP2 by EDX analysis. The bandgaps of ZnSnP2 crystals obtained by cooling rate of 0.7 and 12 °C/h were estimated to be 1.61 and 1.48 eV, respectively, which is caused by the difference of the degree of order. The hall‐resistivity measurement showed that ZnSnP2 crystals with a slow cooling rate has a p‐type conduction. The resistivity, the hole concentration and the mobility are 10∼70 Ωcm, 6·1016∼2·1017 cm‐3, and 1∼3 cm2V‐1s‐1. The obtained properties are suitable for an absorber of photovoltaics. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characteristics of amorphous silica‐modified polyaniline films for ammonia sensor application
Authors: Odarve Majvell Kay , Vequizo Reynaldo
Published: March 2015

The characteristic properties of the nanostructured polyaniline (PAni) films synthesized via chemical oxidative polymerization of aniline on glass substrates using amorphous cristobalite silica (SiO2) as structural growth director are presented in this study. The change in the resistance of the sample was monitored upon exposure to ammonia gas using two‐probe method for two cycles, 40 min each. The structural and morphological property of the PAni/SiO2 samples were studied and compared to PAni samples alone using FTIR spectroscopy and scanning electron microscopy. It was found out that PAni/SiO2 films have higher and uniform response to ammonia with good repeatability during the two cycles and recovery upon removal of ammonia source. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure and optical properties of CdS:O films by cathode sputtering
Authors: Nakajima Masahiro , Asaba Ryo , Suzuki Akinori , Shim Yong‐Gu , Wakita Kazuki , Khalilova Kh. , Mamedov Nazim , Bayramov Ayaz , Huseynov Emil
Published: March 2015

We have studied the structure and optical properties of CdS:O films deposited on SLG (soda lime glass) substrates by cathode sputtering in the atmosphere of oxygen/argon gases. According to X‐ray diffraction (XRD) and confocal Raman scattering data, the films annealed in vacuum at temperatures above 300 °C exhibited crystalline structure of CdS. On the other hand, XRD, confocal Raman scattering, AFM (atomic force microscopy) and TEM (transmission electron microscopy) data indicated amorphous structure nano‐crystallization in CdS:O films annealed in vacuum at 400 °C. For the films, the emissions located at 3.35 eV were evident from photoluminescence measurements. The origin of this energy gap is discussed by taking into account redistribution of electronic density of states in the amorphous phase and quantum‐size effect. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excitonic emission on CuInS2 epitaxial films by pulse laser deposition
Authors: Yoshida Ryo , Po‐Han Tseng , Shim Yong‐Gu , Wakita Kazuki
Published: March 2015

Thin films of epitaxial CuInS2 were deposited on a GaAs substrate at a temperature of 500 ºC by the pulse‐laser‐deposition method. Surface and cross‐section scanning electron microscopy (SEM) images were taken for all the films, with thicknesses estimated to range between 0.5‐1 μm. X‐ray diffraction (XRD) and Raman scattering confirmed the chalcopyrite structure of the films. For a film deposited by a pulse of energy density 0.8 J/cm2, free exciton and bound exciton emissions at 77 K were observed using photoluminescence (PL). The exciton emissions appear only at specific points in a PL‐intensity mapping. In addition, for the points with excitonic emission the composition ratio of the Cu and In was found to be very close to unity compared to other areas without emissions. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐performance a‐Si1–xOx:H/c‐Si heterojunction solar cells realized by the a‐Si:H/a‐Si1–xOx:H stack buffer layer
Authors: Zhang He , Nakada Kazuyoshi , Miyajima Shinsuke , Konagai Makoto
Published: March 2015

We used amorphous silicon oxide (a‐Si1–xOx:H) and microcrystalline silicon oxide (µc‐Si1–xOx:H) as buffer layer and p‐type emitter layer, respectively, in n‐type silicon hetero‐junction (SHJ) solar cells. We proposed to insert a thin (2 nm) intrinsic amorphous silicon (a‐Si:H) thin film between the thin (2.5 nm) a‐Si1–xOx:H buffer layer and the p‐layer to form a stack buffer layer of a‐Si:H/a‐Si1–xOx:H. As a result, a high open‐circuit voltage (VOC) and a high fill factor (FF) were obtained at the same time. Finally, a high efficiency of 19.0% (JSC = 33.46 mA/cm2, VOC = 738 mV, FF = 77.0%) was achieved on a 100 μm thick polished wafer using the stack buffer layer.

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(© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)
Assimilation of cloud information from space‐borne radar and lidar: experimental study using a 1D+4D‐Var technique
Authors: Janisková M.
Published: March 2015

Space‐borne active instruments, providing a vertically resolved characterization of clouds, promise a new dimension of information to be used in numerical weather prediction systems. Research activities are ongoing at the European Centre for Medium‐Range Weather Forecasts to exploit these data for monitoring and assimilation purposes. Using currently available observations from CloudSat and CALIPSO, a technique combining one‐dimensional variational (1D‐Var) assimilation with four‐dimensional variational (4D‐Var) data assimilation has been used to study the impact of cloud‐related observations on analyses and subsequent forecasts. Temperature and specific humidity vertical profiles retrieved from 1D‐Var using observations of cloud radar reflectivity and lidar backscatter, either separately or in combination, were used as pseudo‐observations in the 4D‐Var system. Results indicate that 1D‐Var analyses get closer to assimilated and also independent observations when appropriate quality control, bias correction and error estimate are applied. The performed 1D+4D‐Var assimilation experiments also suggest a slight positive impact of the new observations on the subsequent forecast. Generally, the impact of lidar backscatter from clouds is smaller than that of cloud radar reflectivity.
WRF multi‐physics simulation of clouds in the African region
Authors: Diaz J. P. , González A. , Expósito F. J. , Pérez J. C. , Fernández J. , García‐Díez M. , Taima D.
Published: March 2015

The Weather Research and Forecasting (WRF) model has been used to simulate clouds, and their effects on precipitation and radiation, in Africa. The results have been compared with observational databases, mainly based on satellite measurements. The Cloud Feedback Model Intercomparison Project (CFMIP) Observation Simulator Package (COSP) has been used to consistently compare simulated clouds with satellite data, allowing us to evaluate not only the total cloud cover but also the cloud amount of different cloud types, classified according to their optical thickness and cloud‐top pressure. Nine WRF simulations, for the 2002–2006 period, were carried out to evaluate the influence on cloud cover of different physical parametrizations and model configurations. In general, model simulations show similar results, underestimating total cloud cover in most of the studied region. In the tropical convective area, high clouds are underestimated, but the net effect on the radiation is partially compensated by the overestimation of cloud optical depth. Major differences appear over subtropical areas dominated by marine boundary‐layer clouds, mainly off the coast of Namibia. In this area, simulations show too many thick clouds and too few clouds with lower optical thickness. The net result is an underestimation of low cloud cover. Also, the transition from stratocumulus to shallow cumulus away from the coast is not realistically modelled.
Polymyxin‐B‐immobilized‐fiber column hemoperfusion with oseltamivir treatment for ARDS due to influenza H1N1/09
Authors: Binh Nguyen Gia , Manabe Toshie , Co Dao Xuan , Tuan Nguyen Dang , Thach Pham The , Kudo Koichiro
Published: March 2015

Acute respiratory distress syndrome (ARDS) is one of the severe complications of influenza H1N1/09 infection, resulting in high mortality. Effective treatment strategies for ARDS are needed. This report presents two cases of ARDS due to influenza in Vietnam. Both cases were similar in terms of starting symptoms, the rapid progression to ARDS, and the treatment strategy, direct hemoperfusion with a polymyxin‐B‐immobilized fiber column (PMX‐DHP) and oseltamivir. However, the clinical course of disease and the outcomes were different. For case 1, treatment was initiated on day 4 following the onset of hypoxemia due to ARDS. Symptoms improved rapidly after treatment and the patient was discharged on day 12. For case 2, treatment was initiated on day 9 after the onset of symptoms. Despite intensive therapy, the patient died on day 18. In conclusion, treatment with PMX‐DHP and oseltamivir is effective on ARDS due to influenza but only if initiated early.