bluuebunny/crossref_metadata_2025 huggingface dataset:
OAT3-Mediated Extrusion of the 99mTc-ECD Metabolite in the Mouse Brain
Authors: Kikuchi Tatsuya , Okamura Toshimitsu , Wakizaka Hidekatsu , Okada Maki , Odaka Kenichi , Yui Joji , Tsuji Atsushi B , Fukumura Toshimitsu , Zhang Ming-Rong
Published: February 2014

After administration of the 99mTc complex with N, N'-1,2-ethylenediylbis-L-cysteine diethyl ester (99mTc-ECD), a brain perfusion imaging agent, the radioactive metabolite is trapped in primate brain, but not in mouse and rat. Here, we investigate the involvement of metabolite extrusion by organic anion transporter 3 (OAT3), which is highly expressed at the blood–brain barrier in mice, in this species difference. The efflux rate of radioactivity in the cerebrum of Oat3−/− mice at later phase was 20% of that of control mice. Thus, organic anion transporters in mouse brain would be involved in the low brain retention of radioactivity after 99mTc-ECD administration.
The Predictive Power of Brain mRNA Mappings for in vivo Protein Density: A Positron Emission Tomography Correlation Study
Authors: Rizzo Gaia , Veronese Mattia , Heckemann Rolf A , Selvaraj Sudhakar , Howes Oliver D , Hammers Alexander , Turkheimer Federico E , Bertoldo Alessandra
Published: February 2014

Substantial efforts are being spent on postmortem mRNA transcription mapping on the assumption that in vivo protein distribution can be predicted from such data. We tested this assumption by comparing mRNA transcription maps from the Allen Human Brain Atlas with reference protein concentration maps acquired with positron emission tomography (PET) in two representative systems of neurotransmission (opioid and serotoninergic). We found a tight correlation between mRNA expression and specific binding with 5-HT1A receptors measured with PET, but for opioid receptors, the correlation was weak. The discrepancy can be explained by differences in expression regulation between the two systems: transcriptional mechanisms dominate the regulation in the serotoninergic system, whereas in the opioid system proteins are further modulated after transcription. We conclude that mRNA information can be exploited for systems where translational mechanisms predominantly regulate expression. Where posttranscriptional mechanisms are important, mRNA data have to be interpreted with caution. The methodology developed here can be used for probing assumptions about the relationship of mRNA and protein in multiple neurotransmission systems.
The Pentose Phosphate Pathway and Pyruvate Carboxylation after Neonatal Hypoxic-Ischemic Brain Injury
Authors: Brekke Eva MF , Morken Tora S , Widerøe Marius , Håberg Asta K , Brubakk Ann-Mari , Sonnewald Ursula
Published: February 2014

The neonatal brain is vulnerable to oxidative stress, and the pentose phosphate pathway (PPP) may be of particular importance to limit the injury. Furthermore, in the neonatal brain, neurons depend on de novo synthesis of neurotransmitters via pyruvate carboxylase (PC) in astrocytes to increase neurotransmitter pools. In the adult brain, PPP activity increases in response to various injuries while pyruvate carboxylation is reduced after ischemia. However, little is known about the response of these pathways after neonatal hypoxia-ischemia (HI). To this end, 7-day-old rats were subjected to unilateral carotid artery ligation followed by hypoxia. Animals were injected with [1,2-13C]glucose during the recovery phase and extracts of cerebral hemispheres ipsi- and contralateral to the operation were analyzed using 1H- and 13C-NMR (nuclear magnetic resonance) spectroscopy and high-performance liquid chromatography (HPLC). After HI, glucose levels were increased and there was evidence of mitochondrial hypometabolism in both hemispheres. Moreover, metabolism via PPP was reduced bilaterally. Ipsilateral glucose metabolism via PC was reduced, but PC activity was relatively preserved compared with glucose metabolism via pyruvate dehydrogenase. The observed reduction in PPP activity after HI may contribute to the increased susceptibility of the neonatal brain to oxidative stress.
A Mechanistic Model of Drug‐Induced Liver Injury Aids the Interpretation of Elevated Liver Transaminase Levels in a Phase I Clinical Trial
Authors: Howell BA , Siler SQ , Shoda LKM , Yang Y , Woodhead JL , Watkins PB
Published: February 2014

Entolimod (CBLB502) is a Toll‐like receptor 5 agonist in development as a single‐dose countermeasure against total body irradiation. Efficacy can be assessed from animal studies, but the “Animal Rule” does not apply to safety assessment. Marked elevations of serum aminotransferases (exceeding 1,000 IU/l) were observed in some human subjects receiving Entolimod in a safety study, threatening its continued development. The percentage of total hepatocytes undergoing necrosis in these subjects was estimated using a mechanistic, multiscale, mathematical model (DILIsym). The simulations suggested that no subject in the safety study experienced more than a modest loss of hepatocytes (<5%), which was comparable to estimates from a study of healthy volunteers receiving treatment with heparins. The predicted hepatocyte loss with Entolimod was lower than that required to cause liver dysfunction or that is routinely excised from volunteers donating for autologous liver transplantation and did not likely represent a serious health risk.

CPT Pharmacometrics Syst. Pharmacol. (2014) 3, e98; doi:10.1038/psp.2013.74; published online 5 February 2014
Brownian Motion in a Speckle Light Field: Tunable Anomalous Diffusion and Selective Optical Manipulation
Authors: Volpe Giorgio , Volpe Giovanni , Gigan Sylvain
Published: February 2014

The motion of particles in random potentials occurs in several natural phenomena ranging from the mobility of organelles within a biological cell to the diffusion of stars within a galaxy. A Brownian particle moving in the random optical potential associated to aspeckle pattern, i.e., a complex interference pattern generated by the scattering of coherent light by a random medium, provides an ideal model system to study such phenomena. Here, we derive a theory for the motion of a Brownian particle in a speckle field and, in particular, we identify its universal characteristic timescale. Based on this theoretical insight, we show how speckle light fields can be used to control the anomalous diffusion of a Brownian particle and to perform some basic optical manipulation tasks such as guiding and sorting. Our results might broaden the perspectives of optical manipulation for real-life applications.
Controlling the shape of LiCoPO4 nanocrystals by supercritical fluid process for enhanced energy storage properties
Authors: Truong Quang Duc , Devaraju Murukanahally Kempaiah , Ganbe Yoshiyuki , Tomai Takaaki , Honma Itaru
Published: February 2014

Lithium-ion batteries offer promising opportunities for novel energy storage systems and future application in hybrid electric vehicles or electric vehicles. Cathode materials with high energy density are required for practical application. Herein, high-voltage LiCoPO4 cathode materials with different shapes and well-developed facets such as nanorods and nanoplates with exposed {010} facets have been synthesized by a one-pot supercritical fluid (SCF) processing. The effect of different amines and their roles on the morphology-control has been investigated in detail. It was found that amine having long alkyl chain such as hexamethylenediamine played important roles to manipulate the shape of the nanocrystals by selective adsorption on the specific {010} facets. More importantly, the nanorods and nanoplates showed better electrochemical performance than that of nanoparticles which was attributed to their unique crystallographic orientation with short Li ion diffusion path. The present study emphasizes the importance of crystallographic orientation in improving the electrochemical performance of the high voltage LiCoPO4 cathode materials for Li-ion batteries.
Experimental observation of ferrielectricity in multiferroic DyMn2O5
Authors: Zhao Z. Y. , Liu M. F. , Li X. , Lin L. , Yan Z. B. , Dong S. , Liu J. -M.
Published: February 2014

One of the major breakthroughs associated with multiferroicity in recent years is the discovery of ferroelectricity generated by specific magnetic structures in some magnetic insulating oxides such as rare-earth manganites RMnO3 and RMn2O5. An unresolved issue is the small electric polarization. Relatively large electric polarization and strong magnetoelectric coupling have been found in those manganites of double magnetic ions: magnetic rare-earth R ion and Mn ion, due to the strong R-Mn (4f-3d) interactions. DyMn2O5 is a representative example. We unveil in this work the ferrielectric nature of DyMn2O5, in which the two ferroelectric sublattices with opposite electric polarizations constitute the ferrielectric state. One sublattice has its polarization generated by the symmetric exchange striction from the Mn-Mn interactions, while the polarization of the other sublattice is attributed to the symmetric exchange striction from the Dy-Mn interactions. We present detailed measurements on the electric polarization as a function of temperature, magnetic field and measuring paths. The present experiments may be helpful for clarifying the puzzling issues on the multiferroicity in DyMn2O5 and other RMn2O5 multiferroics.
Autocatalytic Oxidization of Nanosilver and Its Application to Spectral Analysis
Authors: Wen Guiqing , Luo Yanghe , Liang Aihui , Jiang Zhiliang
Published: February 2014

The stable yellow nanosilver (AgNP) and blue nanosilver (AgNPB) sols were prepared by the NaBH4 procedure. The new nanocatalytic reaction of AgNP-NaCl-H2O2 was investigated by surface plasmon resonance (SPR) absorption, resonance Rayleigh scattering (RRS), surface-enhanced Raman scattering (SERS) and scanning electron microscope (SEM) techniques. The autocatalytic oxidization of Ag on AgNP surface by H2O2 was observed firstly and the AgNP/AgCl nanoparticles were characterized. The [Ag+] from AgNP is different to the Ag+ from AgNO3 that adsorb on the AgNP surface. An autocatalytic oxidization mechanism was proposed to explain experimental phenomena. The relationship between the SPR absorption peaks and the RRS peaks of AgNPB was studied and three characteristic RRS peaks called as out-of-plane quadrupole, out-of-plane dipole and in-plane dipole RRS peaks were observed firstly. Using AgNP as nanoprobe, a simple, sensitive and selective RRS method was developed for assay of H2O2 in the range of 2.0 × 10−8-8.0 × 10−5 mol/L.
Modelling phosphorus loading and algal blooms in a Nordic agricultural catchment-lake system under changing land-use and climate
Authors: Couture Raoul-Marie , Tominaga Koji , Starrfelt Jostein , Moe S. Jannicke , Kaste Øyvind , Wright Richard F.
Published: February 2014

A network of process-based mass-balance models for phosphorus dynamics in catchments and lakes provides a new approach to simulate the effect of land-use and climate change on water quality.
Heavy metal recovery from electroplating wastewater by synthesis of mixed-Fe3O4@SiO2/metal oxide magnetite photocatalysts
Authors: Huang Shouqiang , Gu Lin , Zhu Nanwen , Feng Kaili , Yuan Haiping , Lou Ziyang , Li Yiqun , Shan Aidang
Published: February 2014

Heavy metal recovery by the fabrication of mixed-Fe3O4@SiO2/metal oxide magnetite photocatalysts from electroplating wastewater.
New glucuronic acid donors for the modular synthesis of heparan sulfate oligosaccharides
Authors: Dhamale Omkar P. , Zong Chengli , Al-Mafraji Kanar , Boons Geert-Jan
Published: February 2014

A streamlined approach has been developed for the preparation of modular disaccharide building blocks for the assembly of libraries of HS oligosaccharides that avoids postglycosylation oxidation.
Effect of ion doping on the electrochemical performances of LiFePO4–Li3V2(PO4)3composite cathode materials
Authors: Jin Chao , Zhang Xudong , He Wen , Wang Yan , Li Haiming , Wang Zhuo , Bi Zhiying
Published: February 2014

This review highlights the effect of ion doping on the electrochemical performances of LiFePO4–Li3V2(PO4)3composite cathode materials.
Student conceptions about energy transformations: progression from general chemistry to biochemistry
Authors: Wolfson Adele J. , Rowland Susan L. , Lawrie Gwendolyn A. , Wright Anthony H.
Published: February 2014

Students commencing studies in biochemistry must transfer and build on concepts they learned in chemistry and biology classes. It is well established, however, that students have difficulties in transferring critical concepts from general chemistry courses; one key concept is “energy.” Most previous work on students' conception of energy has focused on their understanding of energy in the context of physics (including the idea of “work”) and/or their understanding of energy in classical physical and inorganic chemistry contexts (particularly Gibbs Free Energy changes, the second law of thermodynamics, and equilibrium under standard conditions within a closed system). For biochemistry, students must go beyond those basic thermodynamics concepts of work, standard energy changes, and closed systems, and instead they must consider what energy flow, use, and transformation mean in living, open, and dynamic systems. In this study we explored students' concepts about free energy and flow in biological chemical reactions and metabolic pathways by surveys and in-depth interviews. We worked with students in general chemistry classes and biochemistry courses in both an Australian and a US tertiary institution. We address three primary questions (i) What are the most common alternative conceptions held by students when they explain energy-related phenomena in biochemistry?, (ii) What information do students transfer from introductory chemistry and biology when they are asked to consider energy in a biological reaction or reaction pathway?, and (iii) How do students at varying levels of competence articulate their understandings of energy in pathways and biological reactions? The answers to these questions are used to build a preliminary learning progression for understanding “energy” in biochemistry. We also propose crucial elements of content knowledge that instructors could apply to help students better grasp this threshold concept in biochemistry.
A multifunctional perylenediimide derivative (DTPDI) can be used as a recyclable specific Hg2+ ion sensor and an efficient DNA delivery carrier
Authors: Liu Kelan , Xu Zejun , Yin Meizhen , Yang Wantai , He Bicheng , Wei Wei , Shen Jie
Published: February 2014

A multifunctional perylenediimide derivative (DTPDI) can be used as a recyclable specific Hg2+ ion sensor and an efficient DNA delivery carrier.
Electronic and transport properties of porous graphenes: two-dimensional benzo- and aza-fused π-conjugated-microporous-polymer sheets and boron–nitrogen co-doped derivatives
Authors: Yang Zhao-Di , Wu Wenzhi , Zeng Xiao Cheng
Published: February 2014

2D benzo-CMP and aza-CMP sheets and their BN co-doped derivatives possess distinct structural, electronic and transport properties that are notably different from those of graphene.
Extraction of Pd(ii), Rh(iii) and Ru(iii) from HNO3aqueous solution to betainium bis(trifluoromethanesulfonyl)imide ionic liquid
Authors: Sasaki Kotoe , Takao Koichiro , Suzuki Tomoya , Mori Takahiro , Arai Tsuyoshi , Ikeda Yasuhisa
Published: February 2014

Pd(ii), Rh(iii), and Ru(iii) can be separated mutually through extraction from HNO3(aq) to [Hbet][Tf2N] ionic liquid without any additional extractants.
Heterocycle construction using the biomass-derived building block itaconic acid
Authors: Medway Alexandra M. , Sperry Jonathan
Published: February 2014

This critical review discusses the diverse array of heterocyclic motifs that are available from the biomass-derived building block itaconic acid.
The prediction of candidate genes for cervix related cancer through gene ontology and graph theoretical approach
Authors: Hindumathi V. , Kranthi T. , Rao S. B. , Manimaran P.
Published: February 2014

With rapidly changing technology, the prediction of candidate genes has become an indispensable task in recent years mainly in the field of biological research.
Macroporous carbon decorated with dendritic platinum nanoparticles: one-step synthesis and electrocatalytic properties
Authors: Yu Xueqing , Zhang Yufan , Guo Liping , Wang Liang
Published: February 2014

Dendritic platinum nanoparticle decorated macroporous carbon, a promising electrocatalyst, is fabricated by a one-step synthesis.
Geothermal air conditioning: typical applications using deep-warm and shallow-cool reservoirs for cooling in Perth, Western Australia
Authors: Whittaker Peter B. , Wang Xiaolin , Regenauer-Lieb Klaus , Blair David , Tong Chua Hui
Published: February 2014

Geothermal heat is a sustainable form of alternative energy, commonly associated with the production of electricity along tectonic plate boundaries and in volcanically active zones. Outside of these special regions however it is rare to find a geothermal gradient high enough to achieve pay back on projects for generating electricity. On the other hand regions containing sedimentary aquifers are far more common and these aquifers frequently have a sufficiently high temperature gradient to make direct use of the thermal energy attractive. Meanwhile highly permeable aquifers occurring at shallow depths are possible sources for cooling water or can be both heat sources and sinks when used in combination with heat pumps. We provide a case study for the use of thermally driven absorption chillers on the University of Western Australia campus in Perth and discuss two ongoing projects: one for the heating and cooling of the offices of the Australian Resources Research Council using a reversible heat pump and the other the climate control of the planned Australian International Gravitational Observatory.
Predicting large area surface reconstructions using molecular dynamics methods
Authors: Grochola Gregory , Snook Ian K. , Russo Salvy P.
Published: February 2014

In this paper we discuss a new simulation method that can be used to predict preferred surface reconstructions of model systems by Molecular Dynamics (MD). The method overcomes the limitations imposed by periodic boundary conditions for finite boundary MD simulations which can normally prevent reconstructions. By simulating only the reconstructed surface layer and by removing the periodic boundary effects and the free energy barriers to reconstruction, the method allows surfaces to reconstruct to a preferred structure. We test the method on three types of surfaces: (i) the Au(100) and Pt(100) hexagonally reconstructed surface, (ii) the Au(111) herringbone surfaces, and (iii) the triangularly reconstructed Ag surface layer on a Pt(111) substrate and find the method readily finds lower surface energy reconstructions as preferred by the potential.
Effect of an imperfect interface in a quartz crystal microbalance for detecting the properties of an additional porous layer
Authors: Li Peng , Jin Feng
Published: February 2014

Sauerbrey's equation may yield incorrect results when the upper layer is not rigidly attached onto the quartz crystal plate. Thus, we investigate the effect of an imperfect interface on the anti-plane vibration of a quartz crystal microbalance for detecting the characteristics of the upper transversely isotropic porous layer. Both the stiffness and inertial effect of the porous layer, as well as the influence of an inhomogeneous interface, are considered for an infinite or finite AT-cut (35°15′ cut deviating principal optic axis) quartz plate. The appearance of a weak interface is theoretically and numerically revealed to excite a new thickness twist wave in an infinite quartz crystal plate. Meanwhile, the non-uniform interface evidently changes the displacement and stress distributions, which is totally different from the homogeneous interface. These findings prove effective guidance for physical phenomenon explanations and experimental measurement in mass sensor devices.
Photodissociation dynamics of nitromethane and methyl nitrite by infrared multiphoton dissociation imaging with quasiclassical trajectory calculations: Signatures of the roaming pathway
Authors: Dey Arghya , Fernando Ravin , Abeysekera Chamara , Homayoon Zahra , Bowman Joel M. , Suits Arthur G.
Published: February 2014

We combine the techniques of infrared multiphoton dissociation (IRMPD) with state selective ion imaging to probe roaming dynamics in the unimolecular dissociation of nitromethane and methyl nitrite. Recent theoretical calculations suggest a “roaming-mediated isomerization” pathway of nitromethane to methyl nitrite prior to decomposition. State-resolved imaging of the NO product coupled with infrared multiphoton dissociation was carried out to examine this unimolecular decomposition near threshold. The IRMPD images for the NO product from nitromethane are consistent with the earlier IRMPD studies that first suggested the importance of an isomerization pathway. A significant Λ-doublet propensity is seen in nitromethane IRMPD but not methyl nitrite. The experimental observations are augmented by quasiclassical trajectory calculations for nitromethane and methyl nitrite near threshold for each dissociation pathway. The observation of distinct methoxy vibrational excitation for trajectories from nitromethane and methyl nitrite dissociation at the same total energy show that the nitromethane dissociation bears a nonstatistical signature of the roaming isomerization pathway, and this is possibly responsible for the nitromethane Λ-doublet propensity as well.
Co/Pt multilayer-based magnetic tunnel junctions with a CoFeB/Ta insertion layer
Authors: Ishikawa S. , Sato H. , Yamanouchi M. , Ikeda S. , Fukami S. , Matsukura F. , Ohno H.
Published: February 2014

We investigate properties of magnetic tunnel junctions (MTJs) having a Co/Pt multilayer as a recording layer. A CoFeB layer is inserted between MgO barrier and the recording layer in order to enhance the tunnel magnetoresistance ratio. We show that an additional layer of Ta inserted between CoFeB and Co/Pt multilayer is effective in improving the MTJ properties after annealing. A high effective magnetic anisotropy energy per unit area over 1.2 mJ/m2 is obtained after annealing at 300 °C. Using a 1.6 nm-thick CoFeB insertion layer, both high thermal stability factor of 92 and high tunnel magnetoresistance ratio of 91% are achieved in a MTJ with 17 nm in diameter.
Performance of Tamm-Dancoff approximation on nonadiabatic couplings by time-dependent density functional theory
Authors: Hu Chunping , Sugino Osamu , Watanabe Kazuyuki
Published: February 2014

The Tamm-Dancoff approximation (TDA), widely used in physics to decouple excitations and de-excitations, is well known to be good for the calculation of excitation energies but not for oscillator strengths. In particular, the sum rule is violated in the latter case. The same concern arises within the TDA in the calculation of nonadiabatic couplings (NACs) by time-dependent density functional theory (TDDFT), due to the similarities in the TDDFT formulations of NACs and oscillator strengths [C. Hu, H. Hirai, and O. Sugino, J. Chem. Phys. 127, 064103 (2007)]. In this study, we present a systematic evaluation of the performance of TDDFT/TDA for the calculation of NACs. In the cases we considered, including a variety of systems possessing Jahn-Teller and Renner-Teller intersections, as well as an example with accidental conical intersections, it is found that the TDDFT/TDA performs better than the full TDDFT, contrary to the conjecture that the TDA might cause the NAC results to deteriorate and violate the sum rule. The surprisingly good performance of the TDA for NACs is probably because the TDA can partially compensate for the local-density-approximation error and give better excitation energies in the vicinity of intersections of potential energy surfaces. Our study also shows that it is important to use the TDA based on the rigorous full-TDDFT formulation of NACs, instead of using it based on an alternative approximate formulation.
Properties of the main Mg-related acceptors in GaN from optical and structural studies
Authors: Monemar B. , Paskov P. P. , Pozina G. , Hemmingsson C. , Bergman J. P. , Khromov S. , Izyumskaya V. N. , Avrutin V. , Li X. , Morkoç H. , Amano H. , Iwaya M. , Akasaki I.
Published: February 2014

The luminescent properties of Mg-doped GaN have recently received particular attention, e.g., in the light of new theoretical calculations, where the deep 2.9 eV luminescence band was suggested to be the main optical signature of the substitutional MgGa acceptor, thus, having a rather large binding energy and a strong phonon coupling in optical transitions. We present new experimental data on homoepitaxial Mg-doped layers, which together with the previous collection of data give an improved experimental picture of the various luminescence features in Mg-doped GaN. In n-type GaN with moderate Mg doping (<1018 cm−3), the 3.466 eV ABE1 acceptor bound exciton and the associated 3.27 eV donor-acceptor pair (DAP) band are the only strong photoluminescence (PL) signals at 2 K, and are identified as related to the substitutional Mg acceptor with a binding energy of 0.225 ± 0.005 eV, and with a moderate phonon coupling strength. Interaction between basal plane stacking faults (BSFs) and Mg acceptors is suggested to give rise to a second deeper Mg acceptor species, with optical signatures ABE2 at 3.455 eV and a corresponding weak and broad DAP peak at about 3.15 eV. The 2.9 eV PL band has been ascribed to many different processes in the literature. It might be correlated with another deep level having a low concentration, only prominent at high Mg doping in material grown by the Metal Organic Chemical Vapor Deposition technique. The origin of the low temperature metastability of the Mg-related luminescence observed by many authors is here reinterpreted and explained as related to a separate non-radiative metastable deep level defect, i.e., not the MgGa acceptor.
Effects of flow on topological defects in a nematic liquid crystal near a colloid
Authors: Stieger Tillmann , Schoen Martin , Mazza Marco G.
Published: February 2014

We perform molecular dynamics simulations of a nematic liquid crystal flowing around a colloidal particle. We study the flow-induced modifications of the topological defects in the liquid crystal due to the presence of the colloid. We show that flow distorts Boojum defects into an asymmetrically larger downstream lobe, and that Saturn ring defects are convected downstream along the flow direction, which is in agreement with experimental observations. Additionally, for a Janus colloid with both parallel and perpendicular patches, exhibiting a Boojum defect and a Saturn ring defect, we find that the Boojum defect facing the upstream direction is destroyed and the Saturn ring is convected downstream.
Aluminum Zintl anion moieties within sodium aluminum clusters
Authors: Wang Haopeng , Zhang Xinxing , Ko Yeon Jae , Grubisic Andrej , Li Xiang , Ganteför Gerd , Schnöckel Hansgeorg , Eichhorn Bryan W. , Lee Mal-Soon , Jena P. , Kandalam Anil K. , Kiran Boggavarapu , Bowen Kit H.
Published: February 2014

Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have established that aluminum moieties within selected sodium-aluminum clusters are Zintl anions. Sodium–aluminum cluster anions, NamAln−, were generated in a pulsed arc discharge source. After mass selection, their photoelectron spectra were measured by a magnetic bottle, electron energy analyzer. Calculations on a select sub-set of stoichiometries provided geometric structures and full charge analyses for both cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra), and fragment molecular orbital based correlation diagrams.
The exact wavefunction factorization of a vibronic coupling system
Authors: Chiang Ying-Chih , Klaiman Shachar , Otto Frank , Cederbaum Lorenz S.
Published: February 2014

We investigate the exact wavefunction as a single product of electronic and nuclear wavefunction for a model conical intersection system. Exact factorized spiky potentials and nodeless nuclear wavefunctions are found. The exact factorized potential preserves the symmetry breaking effect when the coupling mode is present. Additionally nodeless wavefunctions are found to be closely related to the adiabatic nuclear eigenfunctions. This phenomenon holds even for the regime where the non-adiabatic coupling is relevant, and sheds light on the relation between the exact wavefunction factorization and the adiabatic approximation.
Infrared laser induced rupture of thin liquid films on stationary substrates
Authors: Wedershoven H. M. J. M. , Berendsen C. W. J. , Zeegers J. C. H. , Darhuber A. A.
Published: February 2014

We studied the deformation and destabilization of thin liquid films on stationary substrates via infrared illumination. The film thickness evolution was measured using interference microscopy. We developed numerical models for the temperature evolution and the liquid redistribution. The substrate wettability is explicitly accounted for via a phenomenological expression for the disjoining pressure. We systematically measured the film thinning- and rupture dynamics as a function of laser power, which are accurately reproduced by the simulations. While smaller laser spots generally lead to shorter rupture times, the latter can become independent of the spotsize for very narrow beams due to capillary suppression.
Note: Optimization of the numerical data analysis for conductivity percolation studies of drying moist porous systems
Authors: Moscicki J. K. , Sokolowska D. , Kwiatkowski L. , Dziob D. , Nowak J.
Published: February 2014

A simplified data analysis protocol, for dielectric spectroscopy use to study conductivity percolation in dehydrating granular media is discussed. To enhance visibility of the protonic conductivity contribution to the dielectric loss spectrum, detrimental effects of either low-frequency dielectric relaxation or electrode polarization are removed. Use of the directly measurable monofrequency dielectric loss factor rather than estimated DC conductivity to parameterize the percolation transition substantially reduces the analysis work and time.
Contact-induced spin polarization of monolayer hexagonal boron nitride on Ni(111)
Authors: Ohtomo Manabu , Yamauchi Yasushi , Kuzubov Alex A. , Eliseeva Natalya S. , Avramov Pavel V. , Entani Shiro , Matsumoto Yoshihiro , Naramoto Hiroshi , Sakai Seiji
Published: February 2014

Hexagonal boron nitride (h-BN) is a promising barrier material for graphene spintronics. In this Letter, spin-polarized metastable de-excitation spectroscopy (SPMDS) is employed to study the spin-dependent electronic structure of monolayer h-BN/Ni(111). The extreme surface sensitivity of SPMDS enables us to elucidate a partial filling of the in-gap states of h-BN without any superposition of Ni 3d signals. The in-gap states are shown to have a considerable spin polarization parallel to the majority spin of Ni. The positive spin polarization is attributed to the π-d hybridization and the effective spin transfer to the nitrogen atoms at the h-BN/Ni(111) interface.
Molecular-scale investigations of structures and surface charge distribution of surfactant aggregates by three-dimensional force mapping
Authors: Suzuki Kazuhiro , Kobayashi Kei , Oyabu Noriaki , Matsushige Kazumi , Yamada Hirofumi
Published: February 2014

Surface charges on nanoscale structures in liquids, such as biomolecules and nano-micelles, play an essentially important role in their structural stability as well as their chemical activities. These structures interact with each other through electric double layers (EDLs) formed by the counter ions in electrolyte solution. Although static-mode atomic force microscopy (AFM) including colloidal-probe AFM is a powerful technique for surface charge density measurements and EDL analysis on a submicron scale in liquids, precise surface charge density analysis with single-nanometer resolution has not been made because of its limitation of the resolution and the detection sensitivity. Here we demonstrate molecular-scale surface charge measurements of self-assembled micellar structures, molecular hemicylinders of sodium dodecyl sulfate (SDS), by three-dimensional (3D) force mapping based on frequency modulation AFM. The SDS hemicylindrical structures with a diameter of 4.8 nm on a graphite surface were clearly imaged. We have succeeded in visualizing 3D EDL forces on the SDS hemicylinder surfaces and obtaining the molecular-scale charge density for the first time. The results showed that the surface charge on the trench regions between the hemicylinders was much smaller than that on the hemicylinder tops. The method can be applied to a wide variety of local charge distribution studies, such as spatial charge variation on a single protein molecule.
Limitations of heterogeneous models of liquid dynamics: Very slow rate exchange in the excess wing
Authors: Samanta Subarna , Richert Ranko
Published: February 2014

For several molecular glass formers, the nonlinear dielectric effects (NDE’s) are investigated for the so-called excess wing regime, i.e., for the relatively high frequencies between 102 and 107 times the peak loss frequency. It is found that significant nonlinear behavior persists across the entire frequency window of this study, and that its magnitude traces the temperature dependence of the activation energy. A time resolved measurement of the dielectric loss at fields up to 480 kV/cm across tens of thousands of periods reveals that it takes an unexpectedly long time for the steady state NDE to develop. For various materials and at different temperatures and frequencies, it is found that the average structural relaxation with time scale τα governs the equilibration of these fast modes that are associated with time constants τ which are up to 107 times shorter than τα. It is argued that true indicators of structural relaxation (such as rate exchange and aging) of these fast modes are slaved to macroscopic softening on the time scale of τα, and thus many orders of magnitude slower than the time constant of the mode itself.
A reconstructive polyamorphous transition in borosilicate glass induced by irreversible compaction
Authors: Fuhrmann Sindy , Deschamps Thierry , Champagnon Bernard , Wondraczek Lothar
Published: February 2014

Understanding the response of glasses to high pressure is of key importance for clarifying energy-dissipation and the origin of material damage during mechanical load. In the absence of shear bands or motile dislocations, pressure-induced deformation is governed by elastic and inelastic structural changes which lead to compaction of the glass network. Here, we report on a pressure-induced reconstructive amorphous-amorphous transition which was detected in sodium borosilicate glass by Raman and Brillouin scattering. The transition occurs through the formation of four-membered danburite-type rings of BO4 and SiO4-tetrahedra. We suggest that the inelastic pressure-resistance is governed by the Si-O-Si-backbone of the mixed borosilicate network. We further show that compaction is accompanied by increasing structural homogeneity and interpret this as a universal phenomenon in non-crystalline materials.
Multiphase effects on spherical Rayleigh-Taylor interfacial instability
Authors: Mankbadi Mina R. , Balachandar S.
Published: February 2014

A spherical shock-tube model is implemented to focus the attention on the flow instability produced by the release of the driver mixture of gas-particles into the cold driven pure gas. Four discontinuous spherical surfaces are produced which are in order from outward to inward the Primary Shock, gas Contact Interface, Particle Interface, and Secondary Shock. An appropriate methodology is developed to capture the base flows and the physics of Rayleigh-Taylor-based instabilities. The interaction forces between the two phases and the heat transfer are modeled for both the base and the perturbation flows. The parametric space is explored by varying the particle characteristics in order to reveal the mechanisms involved. The results indicate that the gas-gas contact interface remains unstable for the multiphase cases; however, the growth rate of the instability is dampened due to the inclusion of the particles. Results are compared with theoretical models to explain the mechanisms involved.
Structural characterisation of BaTiO3 thin films deposited on SrRuO3/YSZ buffered silicon substrates and silicon microcantilevers
Authors: Colder H. , Domengès B. , Jorel C. , Marie P. , Boisserie M. , Guillon S. , Nicu L. , Galdi A. , Méchin L.
Published: February 2014

We report on the progress towards an all epitaxial oxide layer technology on silicon substrates for epitaxial piezoelectric microelectromechanical systems. (101)-oriented epitaxial tetragonal BaTiO3 (BTO) thin films were deposited at two different oxygen pressures, 5.10−2 mbar and 5.10−3 mbar, on SrRuO3/Yttria-stabilized zirconia (YSZ) buffered silicon substrates by pulsed laser deposition. The YSZ layer full (001) orientation allowed the further growth of a fully (110)-oriented conductive SrRuO3 electrode as shown by X-ray diffraction. The tetragonal structure of the BTO films, which is a prerequisite for the piezoelectric effect, was identified by Raman spectroscopy. In the BTO film deposited at 5.10−2 mbar strain was mostly localized inside the BTO grains whereas at 5.10−3 mbar, it was localized at the grain boundaries. The BTO/SRO/YSZ layers were finally deposited on Si microcantilevers at an O2 pressure of 5.10−3 mbar. The strain level was low enough to evaluate the BTO Young modulus. Transmission electron microscopy (TEM) was used to investigate the epitaxial quality of the layers and their epitaxial relationship on plain silicon wafers as well as on released microcantilevers, thanks to Focused-Ion-Beam TEM lamella preparation.
Ultra-wide frequency broadening mechanism for micro-scale electromagnetic energy harvester
Authors: Liu Huicong , How Koh Kah , Lee Chengkuo
Published: February 2014

This work proposed a hybrid frequency broadening (HFB) mechanism in micro-scale for vibration energy harvesting with ultra-wide bandwidth. A strong HFB behavior is induced by the Duffing stiffening of the clamped-clamped beam stretching and further stimulated continuously by three distributed resonances including out-of-plane mode I at 62.9 Hz, torsion mode II at 82.1 Hz, and twist mode III at 150 Hz. At the acceleration of 1.0g, the microfabricated device with a small area of 6 × 6 mm2 is able to broaden the operating bandwidth from 62.9 Hz to be as wide as 383.7 Hz. This design methodology can be implemented for efficient electromagnetic energy harvesting.
Preparation of silver nanoparticles/graphene nanosheets as a catalyst for electrochemical oxidation of methanol
Authors: Han Kun , Miao Peng , Tong Hui , Liu Tao , Cheng Wenbo , Zhu Xiaoli , Tang Yuguo
Published: February 2014

In this report, silver nanoparticles (AgNPs) decorated graphene nanosheets have been prepared based on the reduction of Ag ions by hydroquinone, and their catalytic performance towards the electrochemical oxidation of methanol is investigated. The synthesis of the nano-composite is confirmed by transmission electron microscope measurements and UV-vis absorption spectra. Excellent electrocatalytic performance of the material is demonstrated by cyclic voltammograms. This material also contributes to the low peak potential of methanol oxidation compared with most of the other materials.
Mode switching in a multi-wavelength distributed feedback quantum cascade laser using an external micro-cavity
Authors: Sidler Meinrad , Rauter Patrick , Blanchard Romain , Métivier Pauline , Mansuripur Tobias S. , Wang Christine , Huang Yong , Ryou Jae-Hyun , Dupuis Russell D. , Faist Jérôme , Capasso Federico
Published: February 2014

We demonstrate a multi-wavelength distributed feedback (DFB) quantum cascade laser (QCL) operating in a lensless external micro-cavity and achieve switchable single-mode emission at three distinct wavelengths selected by the DFB grating, each with a side-mode suppression ratio larger than 30 dB. Discrete wavelength tuning is achieved by modulating the feedback experienced by each mode of the multi-wavelength DFB QCL, resulting from a variation of the external cavity length. This method also provides a post-fabrication control of the lasing modes to correct for fabrication inhomogeneities, in particular, related to the cleaved facets position.
Shock-induced plasticity and the Hugoniot elastic limit in copper nano films and rods
Authors: Seif Dariush , Po Giacomo , Crum Ryan , Gupta Vijay , Ghoniem Nasr M.
Published: February 2014

Shock deformation of copper nano-films and nano-rods is examined with Molecular Dynamics (MD) simulations. The influence of the small system size on the onset of plasticity, its origin resulting from the nucleation of dislocation loops, and its reversible nature are determined. While simulations of large systems with periodic boundary conditions indicate that tremendous axial stresses are needed to induce plastic deformation in perfect copper crystals, the present results suggest that the stress levels needed to initiate irreversible plasticity in nano-rods are more than one order of magnitude smaller than what has been reported for bulk single crystals. MD studies of nano-films show that shock waves are purely elastic up until the Hugoniot elastic limit of PHEL ≈ 30–40 GPa, at which point Shockley partial dislocations are internally nucleated at the shock front. However, our recent experiments on shocked nano-rods show that plasticity is evident at much lower axial stress levels, on the order of 1–2 GPa. The present MD simulations of shocked nano-rods show that Shockley partial dislocations prefer to nucleate at lower stresses from the rod surface, at PHEL ≈ 1–2 GPa, consistent with our concurrent experimental observations, leading to surface step formation and mechanical damage. Nucleated dislocations are found to be Shockley partials in the [100] and [111] oriented nano-rods, with the additional presence of perfect dislocations in the latter. MD simulations of rarefaction shock waves in nano-films indicate that they can be spalled via a mechanism of nano-void nucleation, growth and coalescence at the spall plane. The origin of these nano-voids is shown to be at the intersection of stacking faults on conjugate slip {111} planes. Spallation by void nucleation and coalescence is found not to be achievable in nano-rods. Rarefaction shocks with high stresses were found to either severely deform or melt the nano-rod before it can be spalled.
Stability enhancement of an electrically tunable colloidal photonic crystal using modified electrodes with a large electrochemical potential window
Authors: Shim HongShik , Gyun Shin Chang , Heo Chul-Joon , Jeon Seog-Jin , Jin Haishun , Woo Kim Jung , Jin YongWan , Lee SangYoon , Lim Joohyun , Gyu Han Moon , Lee Jin-Kyu
Published: February 2014

The color tuning behavior and switching stability of an electrically tunable colloidal photonic crystal system were studied with particular focus on the electrochemical aspects. Photonic color tuning of the colloidal arrays composed of monodisperse particles dispersed in water was achieved using external electric field through lattice constant manipulation. However, the number of effective color tuning cycle was limited due to generation of unwanted ions by electrolysis of the water medium during electrical switching. By introducing larger electrochemical potential window electrodes, such as conductive diamond-like carbon or boron-doped diamond, the switching stability was appreciably enhanced through reducing the number of ions generated.
Extracting the charge carrier mobility from the nanosecond photocurrent response of organic solar cells and photodiodes
Authors: Christ Nico , Kettlitz Siegfried W. , Mescher Jan , Lemmer Uli
Published: February 2014

We present two simple methods to estimate the effective mobility of the faster charge carrier species from the transient nanosecond photoresponse of an organic solar cell or photodiode. In combination with detailed numerical drift-diffusion simulations in the framework of the multiple-trapping model, we identify the energetic relaxation of the charge carriers and hence a decrease of the effective charge carrier mobility while drifting towards the electrodes. From the characteristic shape of the transient current density, the temperature as well as the nonlinear voltage dependence of the charge carrier transit time, we can quantify an exponential trap distribution. In addition, the nonlinearity of the transit time, as also known from comparable time-of-flight measurements, can be explained by charge carrier relaxation processes in the presence of trap states. The effective charge carrier mobility is shown to be field independent but highly temperature dependent.
Investigation on intergranular exchange coupling effect in Pr9Fe85.5B5.5 ribbons
Authors: Li Z. B. , Zhang M. , Wang L. C. , Shen B. G. , Zhang X. F. , Li Y. F. , Hu F. X. , Sun J. R.
Published: February 2014

The intergranular exchange coupling effects are investigated via thermal activation of magnetization reversal in the magnetic relaxation process, combined with Henkel plots and the measurement of susceptibilities in three types of Pr9Fe85.5B5.5 ribbons. Exchange interaction between hard-hard grains is proposed in optimal melt-spun ribbons, as well as in over melt-spun ribbons even bearing a weak exchange coupling between soft-hard grains. In under melt-spun ribbons, the decoupled effect is proposed between hard-hard grains. These investigations may contribute to a clear understanding about the complicated nature of the intergranular exchange coupling in nanocomposite magnets.
Competing spin pumping effects in magnetic hybrid structures
Authors: Azevedo A. , Alves Santos O. , Fonseca Guerra G. A. , Cunha R. O. , Rodríguez-Suárez R. , Rezende S. M.
Published: February 2014

Pure spin current can be detected by its conversion into charge current in nanometer thick nonmagnetic metal layer with large spin-orbit coupling by means of the inverse spin Hall effect (ISHE). Recently, it has been shown that the metallic ferromagnet Permalloy (Py) can also be used as spin current detector in experiments in which an ISHE voltage is created in a Py layer in contact with the insulating ferromagnet yttrium iron garnet (YIG) under a thermal gradient in the longitudinal spin Seebeck configuration. Here, we report experiments with microwave driven spin pumping in heterostructures made with single crystal YIG film and a nanometer thick Py or Pt layer that show that Py behaves differently than nonmagnetic metals as a spin current detector. The results are attributed to the competition between the spin currents generated by the dynamics of the magnetizations in YIG and in Py, which are exchange coupled at the interface.
Growth and characterization of Sc-doped EuO thin films
Authors: Altendorf S. G. , Reisner A. , Chang C. F. , Hollmann N. , Rata A. D. , Tjeng L. H.
Published: February 2014

The preparation of 3d-transition metal-doped EuO thin films by molecular beam epitaxy is investigated using the example of Sc doping. The Sc-doped EuO samples display a good crystalline structure, despite the relatively small ionic radius of the dopant. The Sc doping leads to an enhancement of the Curie temperature to up to 125 K, remarkably similar to previous observations on lanthanide-doped EuO.