bluuebunny/crossref_metadata_2025 huggingface dataset:
The prevalence and trends in overweight and obesity in Irish adults between 1990 and 2011
Authors: Boylan Elaine A , McNulty Breige A , Walton Janette , Flynn Albert , Nugent Anne P , Gibney Michael J
Published: April 2014

Objective

Obesity is a serious public health issue, the prevalence of which is increasing globally. The present study aimed to investigate trends in overweight and obesity in Irish adults between 1990 and 2011.

Design

Anthropometric data from three Irish national food consumption surveys were used to calculate trends in BMI, waist circumference and waist:hip ratio.

Setting

Three cross-sectional food consumption surveys: the Irish National Nutrition Survey (1990), the North/South Ireland Food Consumption Survey (2001) and the National Adult Nutrition Survey (2011).

Subjects

A collective sample of free-living Irish adults (n3125), aged 18–64 years.

Results

There were significant increases in mean weight, height and BMI from 1990 to 2011. Significant increments were also reported in waist and hip circumferences and waist:hip ratio between 2001 and 2011, with concurrent increases in the proportion of individuals at risk of developing CVD, particularly females aged 18–35 years. In 2011, 23·4 % of the Irish population was classified as obese; with the mean BMI increasing by 1·1 kg/m2between 1990 and 2001 and by 0·6 kg/m2between 2001 and 2011.

Conclusions

The present paper characterises obesity levels in Irish adults from 1990 to 2011. Absolute levels of overweight and obesity have increased between these time points. Of concern is the increase in the proportion of young women classified as at risk of CVD, using waist circumference and waist:hip ratio. Effective prevention strategies are needed to avoid further increases.
MARCH5-mediated quality control on acetylated Mfn1 facilitates mitochondrial homeostasis and cell survival
Authors: Park Y-Y , Nguyen O T K , Kang H , Cho H
Published: April 2014

Mitochondrial dynamics and quality control have a central role in the maintenance of cellular integrity. Mitochondrial ubiquitin ligase membrane-associated RING-CH (MARCH5) regulates mitochondrial dynamics. Here, we show that mitochondrial adaptation to stress is driven by MARCH5-dependent quality control on acetylated Mfn1. Under mitochondrial stress conditions, levels of Mfn1 were elevated twofold and depletion of Mfn1 sensitized these cells to apoptotic death. Interestingly, overexpression of Mfn1 also promoted cell death in these cells, indicating that a fine tuning of Mfn1 levels is necessary for cell survival. MARCH5 binds Mfn1 and the MARCH5-dependent Mfn1 ubiquitylation was significantly elevated under mitochondrial stress conditions along with an increase in acetylated Mfn1. The acetylation-deficient K491R mutant of Mfn1 showed weak interaction with MARCH5 as well as reduced ubiquitylation. Neither was observed in the acetylation mimetic K491Q mutant. In addition, MARCH5-knockout mouse embryonic fibroblast and MARCH5H43W-expressing HeLa cells lacking ubiquitin ligase activity experienced rapid cell death upon mitochondrial stress. Taken together, a fine balance of Mfn1 levels is maintained by MARCH5-mediated quality control on acetylated Mfn1, which is crucial for cell survival under mitochondria stress conditions.
Impact of fire on active layer and permafrost microbial communities and metagenomes in an upland Alaskan boreal forest
Authors: Taş Neslihan , Prestat Emmanuel , McFarland Jack W , Wickland Kimberley P , Knight Rob , Berhe Asmeret Asefaw , Jorgenson Torre , Waldrop Mark P , Jansson Janet K
Published: April 2014

Permafrost soils are large reservoirs of potentially labile carbon (C). Understanding the dynamics of C release from these soils requires us to account for the impact of wildfires, which are increasing in frequency as the climate changes. Boreal wildfires contribute to global emission of greenhouse gases (GHG—CO2, CH4 and N2O) and indirectly result in the thawing of near-surface permafrost. In this study, we aimed to define the impact of fire on soil microbial communities and metabolic potential for GHG fluxes in samples collected up to 1 m depth from an upland black spruce forest near Nome Creek, Alaska. We measured geochemistry, GHG fluxes, potential soil enzyme activities and microbial community structure via 16SrRNA gene and metagenome sequencing. We found that soil moisture, C content and the potential for respiration were reduced by fire, as were microbial community diversity and metabolic potential. There were shifts in dominance of several microbial community members, including a higher abundance of candidate phylum AD3 after fire. The metagenome data showed that fire had a pervasive impact on genes involved in carbohydrate metabolism, methanogenesis and the nitrogen cycle. Although fire resulted in an immediate release of CO2 from surface soils, our results suggest that the potential for emission of GHG was ultimately reduced at all soil depths over the longer term. Because of the size of the permafrost C reservoir, these results are crucial for understanding whether fire produces a positive or negative feedback loop contributing to the global C cycle.
Reversible potentials for steps in methanol and formic acid oxidation to CO2; adsorption energies of intermediates on the ideal electrocatalyst for methanol oxidation and CO2 reduction
Authors: Anderson Alfred B. , Asiri Haleema Aied
Published: April 2014

Theory has predicted reversible potentials for methanol electrooxidation on platinum and the adsorption bond strengths for the ideal catalyst.
Highly active and stable nano NiO–MgO catalyst encapsulated by silica with a core–shell structure for CO2 methanation
Authors: Li Yanrong , Lu Gongxuan , Ma Jiantai
Published: April 2014

Ni–MgO nanoparticles (NPs) encapsulated by porous silica shell for CO2 methanation were synthesized.
Water induced zinc oxide thin film formation and its transistor performance
Authors: Chang Jingjing , Chang Kok Leong , Chi Chunyan , Zhang Jie , Wu Jishan
Published: April 2014

This study reports the effect of water on the formation of a zinc oxide (ZnO) thin film and the performance of ZnO thin film transistors (TFTs).
Simultaneous extraction of anthracyclines from urine using water-compatible magnetic nanoparticles with a dummy template coupled with high performance liquid chromatography
Authors: Zou Wenyue , Dramou Pierre , Ai Pham-Huy Lien , Zhang Kai , He Jia , Pham-Huy Chuong , Xiao Deli , He Hua
Published: April 2014

A detailed discussion was made to explain the adsorption mechanism of the synthesized water-compatible M-MIPs.
SiO2 nanoparticles and diphenylcarbazide doped polymethylmethacrylate electrospun fibrous film for Cd2+ colorimetric detection
Authors: Yao Tianyu , Tu Qin , Han Xiang , Zhang Longlong , Wang Dong-En , Li Manlin , Chen Sheng , Wang Jinyi
Published: April 2014

A method for Cd2+ detection was developed by using SiO2 nanoparticles and diphenylcarbazide doped polymethylmethacrylate electrospun fibrous film.
Metabolite fingerprint analysis of cervical cancer using LC-QTOF/MS and multivariate data analysis
Authors: Liang Qun , Yu Qian , Wu Haikun , Zhu Yong-zhi , Zhang Ai-hua
Published: April 2014

The metabolic fingerprint of urine samples from women diagnosed with CC and control subjects were determined using LC coupled with Q-TOF/MS and independent variable analysis..
A tetranaphthoimidazolium receptor as a fluorescent chemosensor for phytate
Authors: Lee Minji , Moon Jong Hun , Jun Eun Jin , Kim Gyoungmi , Kwon Yong-Uk , Lee Jin Yong , Yoon Juyoung
Published: April 2014

A new tetranaphthoimidazolium receptor showed a selective fluorescence enhancement with phytate, myo-inositol hexakisphosphate (IP6), in 100% aqueous solution at pH 7.4.
An unsaturated hydrogen bonded network generated from three-fold symmetric carbamates
Authors: Wang Zijun , Lee Joseph , Oian Casey , Hou Xiaodong , Wang Zhihan , Ugrinov Angel , Singh Rajiv K. , Wysocki Erin , Chu Qianli R.
Published: April 2014

A new crystalline sheet spontaneously assembled under mild conditions from tri-carbamates. The discovery of the unsaturated hydrogen bonded sheet further demonstrated the variety and adaptability of the sheet structures.
Novel core–shell structured BiVO4 hollow spheres with an ultra-high surface area as visible-light-driven catalyst
Authors: Lu Yang , Luo Yong-Song , Xiao Hong-Mei , Fu Shao-Yun
Published: April 2014

Novel core–shell-structured BiVO4 hollow spheres synthesized via a simple hydrothermal route exhibit an excellent photocatalytic activity.
Hierarchical importance of coordination and hydrogen bonds in the formation of homochiral 2D coordination polymers and 2D supramolecular assemblies
Authors: Kumar Navnita , Khullar Sadhika , Singh Yogesh , Mandal Sanjay K.
Published: April 2014

2D homochiral coordination polymers and their conversion to the corresponding homochiral 2D supramolecular assemblies using 4,4’-bipyridine as a bifunctional linker are reported.
Time-resolved fluorescence spectroscopy study of excited state dynamics of alkyl- and benzo-substituted triphyrin(2.1.1)
Authors: Iima Yusuke , Kuzuhara Daiki , Xue Zhao-Li , Akimoto Seiji , Yamada Hiroko , Tominaga Keisuke
Published: April 2014

Non-radiative relaxation in triphyrin(2.1.1) is found to be due to non-planarity of the macrocycle.
Effect of ordering of PtCu3nanoparticle structure on the activity and stability for the oxygen reduction reaction
Authors: Hodnik Nejc , Jeyabharathi Chinnaiah , Meier Josef C. , Kostka Alexander , Phani Kanala L. , Rečnik Aleksander , Bele Marjan , Hočevar Stanko , Gaberšček Miran , Mayrhofer Karl J. J.
Published: April 2014

The performance enhancement effect of structural ordering for the oxygen reduction reaction (ORR) on the PtCu3nanoparticulate system is systematically studied.
Di- and tri-oxalkyl derivatives of a boron dipyrromethene (BODIPY) rotor dye in lipid bilayers
Authors: Olšinová Marie , Jurkiewicz Piotr , Pozník Michal , Šachl Radek , Prausová Tereza , Hof Martin , Kozmík Václav , Teplý Filip , Svoboda Jiří , Cebecauer Marek
Published: April 2014

Di- and tri-alkylated variants of a BODIPY rotor: carefully characterised probes sensing the liquid or gel state of lipid membranes.
Ga[NO2A-N-(α-amino)propionate] chelates: synthesis and evaluation as potential tracers for 68Ga PET
Authors: Ferreira Miguel F. , Pereira Goretti , André João P. , Prata M. I. M. , Ferreira Paula M. T. , Martins José A. , Geraldes Carlos F. G. C.
Published: April 2014

A reversible pH-trigged N3O3⇆N4O2 coordination isomerism was demonstrated for the Ga[NO2A-N-(α-amino)propionate] chelate in the pH range 4–6.
Zeolite films as building blocks for antireflective coatings and vapor responsive Bragg stacks
Authors: Babeva Tsvetanka , Awala Hussein , Vasileva Marina , El Fallah Jaafar , Lazarova Katerina , Thomas Sebastien , Mintova Svetlana
Published: April 2014

The optical properties of zeolite films and their applications in broadband antireflection coatings and Bragg stacks sensors.
Efficient 2-step biocatalytic strategies for the synthesis of all nor(pseudo)ephedrine isomers
Authors: Sehl Torsten , Hailes Helen C. , Ward John M. , Menyes Ulf , Pohl Martina , Rother Dörte
Published: April 2014

All nor(pseudo)ephedrine isomers can be synthesized step-efficiently in two different 1-pot 2-step biocatalytic cascade reactions in high optical purities.
Comparison of signal enhancement by co-existing carbon and by co-existing bromine in inductively coupled plasma mass spectrometry
Authors: Nakazawa Takashi , Suzuki Daisuke , Sakuma Hironori , Furuta Naoki
Published: April 2014

Co-existing bromine did not enhance the signals of analytes, even though the ionization energy is similar to that of carbon.
Dielectrophoresis-based purification of antibiotic-treated bacterial subpopulations
Authors: Elitas Meltem , Martinez-Duarte Rodrigo , Dhar Neeraj , McKinney John D. , Renaud Philippe
Published: April 2014

This paper describes the ability for dielectrophoresis to enrich and recover antibiotic-treated mycobacteria, based on physico-chemical properties of their membranes.
Lights and shadows on Food Microfluidics
Authors: Escarpa Alberto
Published: April 2014

Food Microfluidics: science, technology and creativity making food analysis safer, faster and easier.
Enhanced water stability and CO2 gas sorption properties of a methyl functionalized titanium metal–organic framework
Authors: Im Ji Hyuk , Ko Nakeun , Yang Seung Jae , Park Hye Jeong , Kim Jaheon , Park Chong Rae
Published: April 2014

A methyl-modified metal–organic framework (m-TiBDC) exhibiting significantly enhanced hydrostability than unmodified TiBDC maintains its framework structure and also CO2 gas adsorption capacity even after its immersion in water for 2 hours.
Development and application of serine/threonine ligation for synthetic protein chemistry
Authors: Liu Han , Li Xuechen
Published: April 2014

The development and application of serine/threonine ligation (STL) in the synthesis of peptides/proteins and cyclic peptides have been reviewed.
Regiocontrolled palladium-catalyzed and copper-mediated C–H bond functionalization of protectedl-histidine
Authors: Mahindra Amit , Jain Rahul
Published: April 2014

Regiocontrolled transition-metal-catalyzed C–H bond arylation of protectedl-histidine with aryl halides as the coupling partner is reported.
Practically convenient and industrially-aligned methods for iridium-catalysed hydrogen isotope exchange processes
Authors: Cochrane A. R. , Idziak C. , Kerr W. J. , Mondal B. , Paterson L. C. , Tuttle T. , Andersson S. , Nilsson G. N.
Published: April 2014

The use of alternative solvents in the iridium-catalysed hydrogen isotope exchange reaction with developing phosphine/NHC Ir(i) complexes has identified reaction media which are more widely applicable than the commonly employed chlorinated solvent, dichloromethane.
Improved selectivity of an engineered multi-product terpene synthase
Authors: Lauchli Ryan , Pitzer Julia , Kitto Rebekah Z. , Kalbarczyk Karolina Z. , Rabe Kersten S.
Published: April 2014

Random mutation of the multi-product sesquiterpene synthase Cop2 generated a mutant that converted the natural substrate farnesyl diphosphate (FPP) into germacrene D-4-ol with 77% selectivity without detrimental effects on wild-type kinetic properties.
CO2-driven vesicle to micelle regulation of amphiphilic copolymer: random versus block strategy
Authors: Liu Hanbin , Guo Zanru , He Shuai , Yin Hongyao , Fei Chenhong , Feng Yujun
Published: April 2014

A vesicle to spherical micelle morphological regulation has been demonstrated with a random copolymer rather than its triblock counterpart.
Surface-enhanced Raman scattering (SERS) chips made from metal nanoparticle-doped polymer fibers
Authors: Gao Wenran , Chen Gang , Xu Weiqing , Yang Chenggong , Xu Shuping
Published: April 2014

We employed an electrospinning method to prepare metal nanoparticle (NP) doped polymer nanofiber mats, which can be easily cut to size and fixed on slides or in microfluidic channels for surface-enhanced Raman scattering (SERS) measurements.
Understanding the effects of electrochemical parameters on the areal capacitance of electroactive polymers
Authors: Shen D. Eric , Estrada Leandro A. , Österholm Anna M. , Salazar Danielle H. , Dyer Aubrey L. , Reynolds John R.
Published: April 2014

A fractional factorial design of experiments allowed us to optimize the areal capacitance of electropolymerized films over 7 variables using a dramatically reduced set of experiments.
Rational design and fabrication of a β-dicalcium silicate-based multifunctional cement with potential for root canal filling treatment
Authors: Yang Xianyan , Liu Min , Zhao Yu , Jia Hongyu , Xu Sanzhong , Li Xigong , Chen Xiaoyi , Zhang Feng , Gao Changyou , Gou Zhongru
Published: April 2014

Gypsum-introduced, CaO-rich dicalcium silicate-based cements exhibit multifunctional physicochemical and biological properties and meet some challenging criteria in root canal therapy.
Retinal metabolism in humans induces the formation of an unprecedented lipofuscin fluorophore ‘pdA2E’
Authors: Wu Yalin , Jin Qiuxia , Yao Ke , Zhao Junli , Chen Jingmeng , Wu Xiaodan , Gan Lishe , Li Jie , Song Xiaohui , Liu Xin , Cai Xianhui
Published: April 2014

Toxic lipofuscin in the RPE (retinal pigment epithelium) is implicated in blindness in AMD (age-related macular degeneration) or recessive Stargardt's disease patients. In the present study, we identified a novel fluorescent lipofuscin component in human and bovine RPEs. Using 1D and 2D NMR and MS, we confirmed the structure of this pigment and called it pdA2E. It exhibits absorbance maxima at 492 and 342 nm, and is susceptible to photocatalytic isomerization and oxidation. This fluorophore was also detected in the eyecup extracts of Abca4−/−Rdh8−/− (Abca4 encodes ATP-binding cassette transporter 4 and Rdh8 encodes retinol dehydrogenase 8) mice, an AMD/recessive Stargardt's disease model. Excess amassing of pdA2E within RPE cells caused significant cell viability loss and membrane damage. The formation of pdA2E occurred when atRAL (all-trans-retinal) reacted with excess ethanolamine in the absence of acetic acid, and the process is likely to involve the participation of three atRAL molecules. Our findings suggest that endogenous pdA2E may serve as a sensitizer for yielding singlet oxygen and a singlet oxygen quencher, as well as a by-product of retinal metabolism, and its complete characterization facilitates the understanding of biosynthetic pathways by which adverse RPE lipofuscin constituents form.
The glycation site specificity of human serum transferrin is a determinant for transferrin's functional impairment under elevated glycaemic conditions
Authors: Silva André M. N. , Sousa Paulo R. H. , Coimbra João T. S. , Brás Natércia F. , Vitorino Rui , Fernandes Pedro A. , Ramos Maria J. , Rangel Maria , Domingues Pedro
Published: April 2014

The mechanisms involving iron toxicity in diabetes mellitus are not completely understood. However, the spontaneous reaction of reducing sugars with protein amino groups, known as glycation, has been shown to compromise the action of Tf (transferrin), the systemic iron transporter. In order to understand the structural alterations that impair its function, Tf was glycated in vitro and the modification sites were determined by MS. Iron binding to glycated Tf was assessed and a computational approach was conducted to study how glycation influences the iron-binding capacity of this protein. Glycated Tf samples were found to bind iron less avidly than non-modified Tf and MS results revealed 12 glycation sites, allowing the establishment of Lys534 and Lys206 as the most vulnerable residues to this modification. Their increased susceptibility to glycation was found to relate to their low side-chain pKa values. Lys534 and Lys206 participate in hydrogen bonding crucial for iron stabilization in the C- and N-lobes of the protein respectively, and their modification is bound to influence iron binding. Furthermore, the orientation of the glucose residues at these sites blocks the entrance to the iron-binding pocket. Molecular dynamics simulations also suggested that additional loss of iron binding capacity may result from the stereochemical effects induced by the glycation of lysine residues that prevent the conformational changes (from open to closed Tf forms) required for metal binding. Altogether, the results indicate that Tf is particularly vulnerable to glycation and that this modification targets spots that are particularly relevant to its function.
Kitaev models based on unitary quantum groupoids
Authors: Chang Liang
Published: April 2014

We establish a generalization of Kitaev models based on unitary quantum groupoids. In particular, when inputting a Kitaev-Kong quantum groupoid \documentclass[12pt]{minimal}\begin{document}$H_\mathcal {C}$\end{document}HC, we show that the ground state manifold of the generalized model is canonically isomorphic to that of the Levin-Wen model based on a unitary fusion category \documentclass[12pt]{minimal}\begin{document}$\mathcal {C}$\end{document}C. Therefore, the generalized Kitaev models provide realizations of the target space of the Turaev-Viro topological quantum field theory based on \documentclass[12pt]{minimal}\begin{document}$\mathcal {C}$\end{document}C.
Molecular dynamics simulation of Coulomb explosion, melting and shock wave creation in silicon after an ionization pulse
Authors: Li Zhongyu , Chen Di , Wang Jing , Shao Lin
Published: April 2014

Strong electronic stopping power of swift ions in a semiconducting or insulating substrate can lead to localized electron stripping. The subsequent repulsive interactions among charged target atoms can cause Coulomb explosion. Using molecular dynamics simulation, we simulate Coulomb explosion in silicon by introducing an ionization pulse lasting for different periods, and at different substrate temperatures. We find that the longer the pulse period, the larger the melting radius. The observation can be explained by a critical energy density model assuming that melting required thermal energy density is a constant value and the total thermal energy gained from Coulomb explosion is linearly proportional to the ionization period. Our studies also show that melting radius is larger at higher substrate temperatures. The temperature effect is explained due to a longer structural relaxation above the melting temperature at original ionization boundary due to lower heat dissipation rates. Furthermore, simulations show the formation of shock waves, created due to the compression from the melting core.
Magnetotransport in MgO-based magnetic tunnel junctions grown by molecular beam epitaxy (invited)
Authors: Andrieu S. , Bonell F. , Hauet T. , Montaigne F. , Calmels L. , Snoeck E. , Lefevre P. , Bertran F.
Published: April 2014

The strong impact of molecular beam epitaxy growth and Synchrotron Radiation characterization tools in the understanding of fundamental issues in nanomagnetism and spintronics is illustrated through the example of fully epitaxial MgO-based Magnetic Tunnel Junctions (MTJs). If ab initio calculations predict very high tunnel magnetoresistance (TMR) in such devices, some discrepancy between theory and experiments still exists. The influence of imperfections in real systems has thus to be considered like surface contaminations, structural defects, unexpected electronic states, etc. The influence of possible oxygen contamination at the Fe/MgO(001) interface is thus studied, and is shown to be not so detrimental to TMR as predicted by ab initio calculations. On the contrary, the decrease of dislocations density in the MgO barrier of MTJs using Fe1−xVx electrodes is shown to significantly increase TMR. Finally, unexpected transport properties in Fe1−XCox/MgO/Fe1−XCox (001) are presented. With the help of spin and symmetry resolved photoemission and ab initio calculation, the TMR decrease for Co content higher than 25% is shown to come from the existence of an interface state and the shift of the empty Δ1 minority spin state towards the Fermi level.
First principles calculation of a large variation in dielectric tensor through the spin crossover in the CsFe[Cr(CN)6] Prussian blue analogue
Authors: Middlemiss Derek S. , Deeth Robert J.
Published: April 2014

The dielectric response of spin-crossover (SCO) materials is a key property facilitating their use in next-generation information processing technologies. Solid state hybrid density functional theory calculations show that the temperature-induced and strongly hysteretic SCO transition in the Cs+Fe2+[Cr3+(CN−)6] Prussian blue analogue (PBA) is associated with a large change (Δ) in both the static, Δɛ0(HS − LS), and high frequency, Δɛ∞(HS − LS) dielectric constants. The SCO-induced variation in CsFe[Cr(CN)6] is significantly greater than the experimental Δɛ values observed previously in other SCO materials. The phonon contribution, Δɛphon(HS − LS), determined within a lattice dynamics approach, dominates over the clamped nuclei term, Δɛ∞(HS − LS), and is in turn dominated by the low-frequency translational motions of Cs+ cations within the cubic voids of the Fe[Cr(CN)6]− framework. The Cs+ translational modes couple strongly to the large unit cell volume change occurring through the SCO transition. PBAs and associated metal-organic frameworks emerge as a potentially fruitful class of materials in which to search for SCO transitions associated with large changes in dielectric response and other macroscopic properties.
A medium-energy photoemission and ab-initio investigation of cubic yttria-stabilised zirconia
Authors: Cousland G. P. , Cui X. Y. , Smith A. E. , Stampfl C. M. , Wong L. , Tayebjee M. , Yu D. , Triani G. , Evans P. J. , Ruppender H.-J. , Jang L.-Y. , Stampfl A. P. J.
Published: April 2014

Experimental and theoretical investigations into the electronic properties and structure of cubic yttria-stabilized zirconia are presented. Medium-energy x-ray photoemission spectroscopy measurements have been carried out for material with a concentration of 8-9 mol. % yttria. Resonant photoemission spectra are obtained for a range of photon energies that traverse the L2 absorption edge for both zirconium and yttrium. Through correlation with results from density-functional theory (DFT) calculations, based on structural models proposed in the literature, we assign photoemission peaks appearing in the spectra to core lines and Auger transitions. An analysis of the core level features enables the identification of shifts in the core level energies due to different local chemical environments of the constituent atoms. In general, each core line feature can be decomposed into three contributions, with associated energy shifts. Their identification with results of DFT calculations carried out for proposed atomic structures, lends support to these structural models. The experimental results indicate a multi-atom resonant photoemission effect between nearest-neighbour oxygen and yttrium atoms. Near-edge x-ray absorption fine structure spectra for zirconium and yttrium are also presented, which correlate well with calculated Zr- and Y-4d electron partial density-of-states and with Auger electron peak area versus photon energy curve.
Pulsed magnetic field measurement system based on colossal magnetoresistance-B-scalar sensors for railgun investigation
Authors: Stankevič T. , Medišauskas L. , Stankevič V. , Balevičius S. , Žurauskienė N. , Liebfried O. , Schneider M.
Published: April 2014

A high pulsed magnetic field measurement system based on the use of CMR-B-scalar sensors was developed for the investigations of the electrodynamic processes in electromagnetic launchers. The system consists of four independent modules (channels) which are controlled by a personal computer. Each channel is equipped with a CMR-B-scalar sensor connected to the measurement device—B-scalar meter. The system is able to measure the magnitude of pulsed magnetic fields from 0.3 T to 20 T in the range from DC up to 20 kHz independently of the magnetic field direction. The measurement equipment circuit is electrically separated from the ground and shielded against low and high frequency electromagnetic noise. The B-scalar meters can be operated in the presence of ambient pulsed magnetic fields with amplitudes up to 0.2 T and frequencies higher than 1 kHz. The recorded signals can be transmitted to a personal computer in a distance of 25 m by means of a fiber optic link. The system was tested using the electromagnetic railgun RAFIRA installed at the French-German Research Institute of Saint-Louis, France.
Theoretical prediction of nuclear magnetic shieldings and indirect spin-spin coupling constants in 1,1-, cis-, and trans-1,2-difluoroethylenes
Authors: Nozirov Farhod , Kupka Teobald , Stachów Michał
Published: April 2014

A theoretical prediction of nuclear magnetic shieldings and indirect spin-spin coupling constants in 1,1-, cis- and trans-1,2-difluoroethylenes is reported. The results obtained using density functional theory (DFT) combined with large basis sets and gauge-independent atomic orbital calculations were critically compared with experiment and conventional, higher level correlated electronic structure methods. Accurate structural, vibrational, and NMR parameters of difluoroethylenes were obtained using several density functionals combined with dedicated basis sets. B3LYP/6-311++G(3df,2pd) optimized structures of difluoroethylenes closely reproduced experimental geometries and earlier reported benchmark coupled cluster results, while BLYP/6-311++G(3df,2pd) produced accurate harmonic vibrational frequencies. The most accurate vibrations were obtained using B3LYP/6-311++G(3df,2pd) with correction for anharmonicity. Becke half and half (BHandH) density functional predicted more accurate 19F isotropic shieldings and van Voorhis and Scuseria's τ-dependent gradient-corrected correlation functional yielded better carbon shieldings than B3LYP. A surprisingly good performance of Hartree-Fock (HF) method in predicting nuclear shieldings in these molecules was observed. Inclusion of zero-point vibrational correction markedly improved agreement with experiment for nuclear shieldings calculated by HF, MP2, CCSD, and CCSD(T) methods but worsened the DFT results. The threefold improvement in accuracy when predicting 2J(FF) in 1,1-difluoroethylene for BHandH density functional compared to B3LYP was observed (the deviations from experiment were −46 vs. −115 Hz).
Impact of parasitic thermal effects on thermoelectric property measurements by Harman method
Authors: Kwon Beomjin , Baek Seung-Hyub , Keun Kim Seong , Kim Jin-Sang
Published: April 2014

Harman method is a rapid and simple technique to measure thermoelectric properties. However, its validity has been often questioned due to the over-simplified assumptions that this method relies on. Here, we quantitatively investigate the influence of the previously ignored parasitic thermal effects on the Harman method and develop a method to determine an intrinsic ZT. We expand the original Harman relation with three extra terms: heat losses via both the lead wires and radiation, and Joule heating within the sample. Based on the expanded Harman relation, we use differential measurement of the sample geometry to measure the intrinsic ZT. To separately evaluate the parasitic terms, the measured ZTs with systematically varied sample geometries and the lead wire types are fitted to the expanded relation. A huge discrepancy (∼28%) of the measured ZTs depending on the measurement configuration is observed. We are able to separately evaluate those parasitic terms. This work will help to evaluate the intrinsic thermoelectric property with Harman method by eliminating ambiguities coming from extrinsic effects.
Effects of electrode size and solid barrier orientation on streamer discharge in transformer oil
Authors: Jadidian J. , Zahn M. , Lavesson N. , Widlund O. , Borg K.
Published: April 2014

Geometrical effects of electrodes and solid barriers immersed in transformer oil are investigated on positive streamer initiation, propagation, and transformation to surface flashover using a 2-D axisymmetric model. Electrode radii of curvature in the range of 20 μm to 6.35 mm are selected such that only positive streamers form. Modeling results indicate that the positive electrode size directly determines the streamer initiation voltage, while breakdown voltage and delay are mainly determined by the grounded electrode size. Specifically, sharper positive electrodes require lower voltages to initiate positive streamers and sharper grounded electrodes result in lower delays and higher breakdown voltages. Incorporating perpendicular and parallel orientations of solid barrier interfaces in the electrohydrodynamic model shows that polarization forces from the barrier dielectrics on charge carrying streamers are proportional to the permittivity difference between transformer oil and the solid dielectric. If the barrier permittivity is greater than the oil permittivity, the solid dielectric applies an attractive force on the volume charge that turns the streamer into a surface flashover expanding on the barrier surface. On the other hand, a low permittivity pressboard interface repels the approaching streamer. Theoretical analysis of electric field propagation and charge distribution along the streamers, surface flashovers, and through the interfacial surfaces is presented. Barrier dielectric relative permittivities of 1.1 and 4.4 have been studied while the oil relative permittivity is assumed 2.2.
Microrheology close to an equilibrium phase transition
Authors: Reinhardt J. , Scacchi A. , Brader J. M.
Published: April 2014

We investigate the microstructural and microrheological response to a tracer particle of a two-dimensional colloidal suspension under thermodynamic conditions close to a liquid-gas phase boundary. On the liquid side of the binodal, increasing the velocity of the (repulsive) tracer leads to the development of a pronounced cavitation bubble, within which the concentration of colloidal particles is strongly depleted. The tendency of the liquid to cavitate is characterized by a dimensionless “colloidal cavitation” number. On the gas side of the binodal, a pulled (attractive) tracer leaves behind it an extended trail of colloidal liquid, arising from downstream advection of a wetting layer on its surface. For both situations the velocity dependent friction is calculated.
Particle-in-cell simulations of velocity scattering of an anisotropic electron beam by electrostatic and electromagnetic instabilities
Authors: Fu X. R. , Cowee M. M. , Liu K. , Peter Gary S. , Winske D.
Published: April 2014

The velocity space scattering of an anisotropic electron beam (T⊥b/T∥b>1) flowing along a background magnetic field B0 through a cold plasma is investigated using both linear theory and 2D particle-in-cell simulations. Here, ⊥ and ∥ represent the directions perpendicular and parallel to B0, respectively. In this scenario, we find that two primary instabilities contribute to the scattering in electron pitch angle: an electrostatic electron beam instability and a predominantly parallel-propagating electromagnetic whistler anisotropy instability. Our results show that at relative beam densities nb/ne≤0.05 and beam temperature anisotropies Tb⊥/Tb∥≤25, the electrostatic beam instability grows much faster than the whistler instabilities for a reasonably fast hot beam. The enhanced fluctuating fields from the beam instability scatter the beam electrons, slowing their average speed and increasing their parallel temperature, thereby increasing their pitch angles. In an inhomogeneous magnetic field, such as the geomagnetic field, this could result in beam electrons scattered out of the loss cone. After saturation of the electrostatic instability, the parallel-propagating whistler anisotropy instability shows appreciable growth, provided that the beam density and late-time anisotropy are sufficiently large. Although the whistler anisotropy instability acts to pitch-angle scatter the electrons, reducing perpendicular energy in favor of parallel energy, these changes are weak compared to the pitch-angle increases resulting from the deceleration of the beam due to the electrostatic instability.
Large-scale synthesis of BaxSr1−xTiO3 nanowires with controlled stoichiometry
Authors: Tang Haixiong , Zhou Zhi , Sodano Henry A.
Published: April 2014

This study demonstrates a highly efficient method for large-scale synthesis BaTiO3 nanowires (NWs) using a two-step hydrothermal reaction. This synthesis process provides a facile approach to the growth of BaTiO3 NWs with high yield and control over the stoichiometry of the BaxSr1−xTiO3 solid solution. The ferroelectricity of the BaTiO3 NWs is directly characterized using atomic force microscopy with the piezoelectric strain coupling coefficient (d33) reaching 31.1 pm/V. This work provide an avenue for high volume manufacturing of ferroelectric NWs, allowing both fundamental investigation of nanoscale ferroelectricity as well as their future application in the electrical devices.
Electromigration kinetics and critical current of Pb-free interconnects
Authors: Lu Minhua , Rosenberg Robert
Published: April 2014

Electromigration kinetics of Pb-free solder bump interconnects have been studied using a single bump parameter sweep technique. By removing bump to bump variations in structure, texture, and composition, the single bump sweep technique has provided both activation energy and power exponents that reflect atomic migration and interface reactions with fewer samples, shorter stress time, and better statistics than standard failure testing procedures. Contact metallurgies based on Cu and Ni have been studied. Critical current, which corresponds to the Blech limit, was found to exist in the Ni metallurgy, but not in the Cu metallurgy. A temperature dependence of critical current was also observed.
Comparative study of field-dependent carrier dynamics and emission kinetics of InGaN/GaN light-emitting diodes grown on (112¯2) semipolar versus (0001) polar planes
Authors: Ji Yun , Liu Wei , Erdem Talha , Chen Rui , Tiam Tan Swee , Zhang Zi-Hui , Ju Zhengang , Zhang Xueliang , Sun Handong , Wei Sun Xiao , Zhao Yuji , DenBaars Steven P. , Nakamura Shuji , Volkan Demir Hilmi
Published: April 2014

The characteristics of electroluminescence (EL) and photoluminescence (PL) emission from GaN light-emitting diodes (LEDs) grown on (112¯2) semipolar plane and (0001) polar plane have been comparatively investigated. Through different bias-dependent shifting trends observed from the PL and time-resolved PL spectra (TRPL) for the two types of LEDs, the carrier dynamics within the multiple quantum wells (MQWs) region is systematically analyzed and the distinct field-dependent emission kinetics are revealed. Moreover, the polarization induced internal electric field has been deduced for each of the LEDs. The relatively stable emission behavior observed in the semipolar LED is attributed to the smaller polarization induced internal electric field. The study provides meaningful insight for the design of quantum well (QW) structures with high radiative recombination rates.
Emergent spin electromagnetism induced by magnetization textures in the presence of spin-orbit interaction (invited)
Authors: Tatara Gen , Nakabayashi Noriyuki
Published: April 2014

Emergent electromagnetic field which couples to electron's spin in ferromagnetic metals is theoretically studied. Rashba spin-orbit interaction induces spin electromagnetic field which is in the linear order in gradient of magnetization texture. The Rashba-induced effective electric and magnetic fields satisfy in the absence of spin relaxation the Maxwell's equations as in the charge-based electromagnetism. When spin relaxation is taken into account besides spin dynamics, a monopole current emerges generating spin motive force via the Faraday's induction law. The monopole is expected to play an important role in spin-charge conversion and in the integration of spintronics into electronics.
Static and reversible elastic strain effects on magnetic order of La0.7Ca0.3MnO3/SrTiO3 superlattices
Authors: Das Sujit , Herklotz Andreas , Jia Guo Er , Dörr Kathrin
Published: April 2014

[La0.7Ca0.3MnO3(2.6 nm)/SrTiO3(6.3 nm)]15 superlattices (SLs) have been simultaneously grown by Pulsed Laser Deposition (PLD) on different oxide substrates in an attempt to obtain different residual strain states. The substrates are (100)-oriented SrTiO3 (STO), LaAlO3 (LAO), and piezoelectric 0.72Pb (Mg1.3 Nb2.3)3-0.28PbTiO3 (PMN-PT). The La0.7Ca0.3MnO3 layers show tensile strain of ε = 1% on LAO and stronger strain on STO and PMN-PT (ε = 1.7%). The magnetization has been measured and is found to be quite different for the three SLs. Reversible biaxial compression of Δε=−0.1% using the PMN-PT substrate helps one to estimate which part of the differences in magnetic order among the samples is induced by elastic strain. The influence of elastic strain is found to be substantial, but does not completely account for the different behavior of the samples.
Investigation of the sol-gel transition of gelatin using terahertz time-domain spectroscopy
Authors: Kawabe Shunsuke , Seki Munetoshi , Tabata Hitoshi
Published: April 2014

The sol-gel transition temperature of gelatin is determined using viscoelasticity measurement and terahertz time-domain spectroscopy. From the results of the viscoelasticity measurement, the sol-gel transition temperature is determined to be 30–32 °C, and it strongly depended on the concentration. However, terahertz time-domain spectroscopy indicates a particular transition temperature of 36 °C. A distinction of these transition temperatures is attributed to the difference in the structural changes detected by these measurements.
Influences of Ni-Co-B catalyst on the thermal decomposition of light-weight NaNH2-NaBH4 hydrogen storage material
Authors: Bai Ying , Wu Feng , Yang Jian-hu , Wu Chuan , Bao Li-ying
Published: April 2014

NaNH2 and NaBH4 were utilized to prepare a composite hydrogen storage material, NaNH2-NaBH4. To improve the thermal decomposition kinetics of NaNH2-NaBH4, which is crucial for hydrogen-release performance, Ni-Co-B was selected as a catalyst. To prepare the catalyst-promoted light-weight hydrogen storage materials, a composite hydrogen storage system was synthesized via a ball milling method with NaNH2, NaBH4, and Ni-Co-B. X-ray diffraction patterns show that the crystal structure of the NaNH2-NaBH4 is well maintained after adding catalysts. In addition, Na3BN2 and metal Na were detected as by-products in the Ni-Co-B-promoted NaNH2-NaBH4 (with a molar ratio of 2:1) after the thermal decomposition process. In addition, thermogravimetry-differential thermal analysis indicates that the main decomposition stages of the metal boride-promoted NaNH2-NaBH4 materials were split into three stages. Furthermore, the catalytic effects on the thermal decomposition kinetics were evaluated. The activation energy of the Ni-Co-B-promoted NaNH2-NaBH4 below 250 °C is 99 kJ/mol, which is only 62.0% of that of pristine NaNH2-NaBH4 (2/1), implying better kinetics in the low temperature decomposition range.
Effects of ion and nanosecond-pulsed laser co-irradiation on the surface nanostructure of Au thin films on SiO2 glass substrates
Authors: Yu Ruixuan , Shibayama Tamaki , Meng Xuan , Takayanagi Shinya , Yatsu Shigeo , Ishioka Junya , Watanabe Seiichi
Published: April 2014

Ion irradiation and short-pulsed laser irradiation can be used to form nanostructures on the surfaces of substrates. This work investigates the synergistic effects of ion and nanosecond-pulsed laser co-irradiation on surface nanostructuring of Au thin films deposited under vacuum on SiO2 glass substrates. Gold nanoparticles are randomly formed on the surface of the substrate after nanosecond-pulsed laser irradiation under vacuum at a wavelength of 532 nm with a repetition rate of 10 Hz and laser energy density of 0.124 kJ/m2. Gold nanoparticles are also randomly formed on the substrate after 100-keV Ar+ ion irradiation at doses of up to 3.8 × 1015 ions/cm2, and nearly all of these nanoparticles are fully embedded in the substrate. With increasing ion irradiation dose (number of incident laser pulses), the mean diameter of the Au nanoparticles decreases (increases). However, Au nanoparticles are only formed in a periodic surface arrangement after co-irradiation with 6000 laser pulses and 3.8 × 1015 ions/cm2. The periodic distance is ∼540 nm, which is close to the wavelength of the nanosecond-pulsed laser, and the mean diameter of the Au nanoparticles remains at ∼20 nm with a relatively narrow distribution. The photoabsorption peaks of the ion- or nanosecond-pulsed laser-irradiated samples clearly correspond to the mean diameter of Au nanoparticles. Conversely, the photoabsorption peaks for the co-irradiated samples do not depend on the mean nanoparticle diameter. This lack of dependence is likely caused by the periodic nanostructure formed on the surface by the synergistic effects of co-irradiation.
On the location and stability of charge in SiO2/SiNx dielectric double layers used for silicon surface passivation
Authors: Bonilla Ruy S. , Reichel Christian , Hermle Martin , Wilshaw Peter R.
Published: April 2014

Dielectric double layers of thermal silicon dioxide–chemical vapour deposition (CVD) silicon nitride are found to produce excellent passivation of silicon surfaces by combining a chemical reduction of surface defect states, with a field effect reduction of carriers at the surface due to charge in the dielectrics. The charge present in such double-layers has previously been attributed to be characteristic of the interface between the two. However, experimental evidence shows this is indirect and inconclusive. This manuscript reports direct measurements that show the charge lies within 10 nm of the interface between passivating double layers of thermal silicon dioxide–plasma CVD silicon nitride. In addition, the passivation efficiency of oxide-nitride layers, deposited using optimised conditions, was found to be largely unaffected by extra charge subsequently added to the film. The passivation efficiency of textured surfaces or those produced using non-optimised deposition conditions is found to be highly dependent on the field effect component provided by extra deposited charge. Using such extra field effect component, surface recombination velocities <2 cm/s have been obtained on single oxide and oxide/nitride double layers. The extra deposited charge was found to have good long term stability when the dielectric films are submitted to a chemical treatment. By contrast, poor stability of the deposited charge was observed when subjected to ultraviolet radiation. These results point to the importance of the interface between dielectrics when considering how to optimise the charge present in passivating dielectric films.
Quantitative comparison between Z1∕2 center and carbon vacancy in 4H-SiC
Authors: Kawahara Koutarou , Thang Trinh Xuan , Tien Son Nguyen , Janzén Erik , Suda Jun , Kimoto Tsunenobu
Published: April 2014

In this study, to reveal the origin of the Z1∕2 center, a lifetime killer in n-type 4H-SiC, the concentrations of the Z1∕2 center and point defects are compared in the same samples, using deep level transient spectroscopy (DLTS) and electron paramagnetic resonance (EPR). The Z1∕2 concentration in the samples is varied by irradiation with 250 keV electrons with various fluences. The concentration of a single carbon vacancy (VC) measured by EPR under light illumination can well be explained with the Z1∕2 concentration derived from C-V and DLTS irrespective of the doping concentration and the electron fluence, indicating that the Z1∕2 center originates from a single VC.
Substrate induced modulation of electronic, magnetic and chemical properties of MoSe2 monolayer
Authors: Wasey A. H. M. Abdul , Chakrabarty Soubhik , Das G. P.
Published: April 2014

Monolayer of MoSe2, having a typical direct band gap of ∼1.5 eV, is a promising material for optoelectronic and solar cell applications. When this 2D semiconductor is supported on transition metal substrates, such as Ni(111) and Cu(111), its electronic structure gets modulated. First principles density functional investigation shows the appearance of de-localized mid-gap states in the density of states. The work function of the semiconductor overlayer gets modified considerably, indicating n-type doping caused by the metal contacts. The charge transfer across the metal-semiconductor junction also significantly enhances the chemical reactivity of the MoSe2 overlayer, as observed by Hydrogen absorption. Furthermore, for Ni contact, there is a signature of induced magnetism in MoSe2 monolayer.