bluuebunny/crossref_metadata_2025 huggingface dataset:
Maternal diet-induced obesity and offspring cardiovascular health
Authors: Blackmore H. L. , Ozanne S. E.
Published: January 2013

It is widely recognized that environmental insults during adulthood including smoking, lack of exercise and a poor diet increases an individual's risk of cardiovascular disease (CVD). However, research initiated over the last two decades has highlighted that our risk of CVD can be programmed following adverse exposures during early development. Such adverse exposures may include, undernutrition, placental insufficiency, hypoxia, overnutrition and obesity. This review aims to address the current Western obesity crisis by addressing the long-term impact of maternal overnutrition and obesity on the offspring's future risk of CVD. Although current human studies have observed the presence of adverse CVD markers in children born to obese mothers, animal models have proved vital in understanding the underlying mechanisms involved. Mechanisms suggested to be involved in the programming of CVD in the offspring include increased oxidative stress, inflammation, lipotoxicity and epigenetics. CVD remains the greatest cause of death worldwide, therefore further understanding of the mechanisms mediating these effects is important in the development of intervention strategies.
Educating the brain
Authors: Weigmann Katrin
Published: January 2013

Insights from neuroscience can help us understand what goes on in the brain when we learn. Such insights might have an impact on educational practice in schools and help design programmes for those with learning impairments.
Caspase signalling in the absence of apoptosis drives Jnk‐dependent invasion
Authors: Rudrapatna Vivek A , Bangi Erdem , Cagan Ross L
Published: January 2013

Tumours evolve several mechanisms to evade apoptosis, yet many resected carcinomas show significantly elevated caspase activity. Moreover, caspase activity is positively correlated with tumour aggression and adverse patient outcome. These observations indicate that caspases might have a functional role in promoting tumour invasion and metastasis. Using a Drosophila model of invasion, we show that precise effector caspase activity drives cell invasion without initiating apoptosis. Affected cells express the matrix metalloprotinase Mmp1 and invade by activating Jnk. Our results link Jnk and effector caspase signalling during the invasive process and suggest that tumours under apoptotic stresses from treatment, immune surveillance or intrinsic signals might be induced further along the metastatic cascade.
The puzzle of TRPV4 channelopathies
Authors: Nilius Bernd , Voets Thomas
Published: January 2013

Hereditary channelopathies, that is, mutations in channel genes that alter channel function and are causal for the pathogenesis of the disease, have been described for several members of the transient receptor potential channel family. Mutations in the TRPV4 gene, encoding a polymodal Ca2+ permeable channel, are causative for several human diseases, which affect the skeletal system and the peripheral nervous system, with highly variable phenotypes. In this review, we describe the phenotypes of TRPV4 channelopathies and overlapping symptoms. Putative mechanisms to explain the puzzle, and how mutations in the same region of the channel cause different diseases, are discussed and experimental approaches to tackle this surprising problem are suggested.
Gradient-free directional cell migration in continuous microchannels
Authors: Ko Young-Gwang , Co Carlos C. , Ho Chia-Chi
Published: January 2013

The continuous zig-zag microchannel design enables sustained autonomous directional cell migration without chemical or mechanical gradient.
Sox2 protects neural stem cells from apoptosis via up-regulating survivin expression
Authors: Feng Ruopeng , Zhou Shixin , Liu Yinan , Song Daijun , Luan Zhilin , Dai Xin , Li Yang , Tang Na , Wen Jinhua , Li Lingsong
Published: January 2013

The transcription factor Sox2 [SRY (sex-determining region Y)-box 2] is essential for the regulation of self-renewal and homoeostasis of NSCs (neural stem cells) during brain development. However, the downstream targets of Sox2 and its underlying molecular mechanism are largely unknown. In the present study, we found that Sox2 directly up-regulates the expression of survivin, which inhibits the mitochondria-dependent apoptotic pathway in NSCs. Although overexpression of Sox2 elevates survivin expression, knockdown of Sox2 results in a decrease in survivin expression, thereby initiating the mitochondria-dependent apoptosis related to caspase 9 activation. Furthermore, cell apoptosis owing to knockdown of Sox2 can be rescued by ectopically expressing survivin in NSCs as well as in the mouse brain, as demonstrated by an in utero-injection approach. In short, we have found a novel Sox2/survivin pathway that regulates NSC survival and homoeostasis, thus revealing a new mechanism of brain development, neurological degeneration and such aging-related disorders.
Efficiency droop in InSb/AlInSb quantum-well light-emitting diodes
Authors: Nash G. R. , Mirza B. I.
Published: January 2013

Efficiency droop in InSb/AlxIn1−xSb quantum-well light-emitting diodes has been investigated as a function of temperature for devices containing 20 nm, 40 nm, and 100 nm wide quantum well active regions. The amount of droop is greatest at low temperatures in device with the widest wells.
The Lichnerowicz-Weitzenböck formula and superconductivity
Authors: Vargas-Paredes Alfredo A. , Doria Mauro M. , Neto José Abdala Helayël
Published: January 2013

We derive the Lichnerowicz-Weitzenböck formula for the two-component order parameter superconductor, which provides a twofold view of the kinetic energy of the superconductor. For the one component order parameter superconductor we review the connection between the Lichnerowicz-Weitzenböck formula and the Ginzburg-Landau theory. For the two-component case we claim that this formula opens a venue to describe inhomogeneous superconducting states intertwined by spin correlations and charged dislocation. In this case the Lichnerowicz-Weitzenböck formula displays local rotational and electromagnetic gauge symmetry (SU(2) ⊗ U(1)) and relies on local commuting momentum and spin operators. The order parameter lives in a space with curvature and torsion described by Élie Cartan geometrical formalism. The Lichnerowickz-Weitzenböck formula leads to first order differential equations that are a three-dimensional version of the Seiberg-Witten equations.
Dynamic heterogeneities above and below the mode-coupling temperature: Evidence of a dynamic crossover
Authors: Flenner Elijah , Szamel Grzegorz
Published: January 2013

We examine dynamic heterogeneities in a model glass-forming fluid, a binary harmonic sphere mixture, above and below the mode-coupling temperature Tc. We calculate the ensemble independent susceptibility χ4(τα) and the dynamic correlation length ξ4(τα) at the α-relaxation time τα. We also examine in detail the temperature dependence of τα and the diffusion coefficient D. For higher temperatures, we find that the standard Stokes-Einstein relationship, \documentclass[12pt]{minimal}\begin{document}$D \sim \tau _\alpha ^{-1}$\end{document}D∼τα−1, holds, but at lower temperatures a fractional Stokes-Einstein relationship, \documentclass[12pt]{minimal}\begin{document}$D \sim \tau _\alpha ^{-\sigma }$\end{document}D∼τα−σ with σ = 0.65, emerges. By examining the relationships between τα, D, χ4(τα), and ξ4(τα) we determine that the emergence of the fractional Stokes-Einstein relationship is accompanied by a dynamic crossover from \documentclass[12pt]{minimal}\begin{document}$\tau _\alpha \sim e^{k_2 \xi _4}$\end{document}τα∼ek2ξ4 at higher temperatures to \documentclass[12pt]{minimal}\begin{document}$\tau _\alpha \sim e^{k_1 \xi _4^{3/2}}$\end{document}τα∼ek1ξ43/2 at lower temperatures.
Observation of ion scale fluctuations in the pedestal region during the edge-localized-mode cycle on the National Spherical Torus Experiment
Authors: Diallo A. , Kramer G. J. , Smith D. R. , Maingi R. , Bell R. E. , Guttenfelder W. , LeBlanc B. P. , Podestà M. , McKee G. J. , Fonck R.
Published: January 2013

Characterization of the spatial structure of turbulence fluctuations during the edge localized mode cycle in the pedestal region is reported. Using the beam emission spectroscopy and the correlation reflectometry systems, measurements show spatial structure—k⊥ρiped—ranging from 0.2 to 0.7 propagating in the ion diamagnetic drift direction at the pedestal top. These propagating spatial scales are found to be anisotropic and consistent with ion-scale microturbulence of the type ion temperature gradient and/or kinetic ballooning modes.
Invariants and reduced matrix elements associated with the Lie superalgebra gl(m|n)
Authors: Gould Mark D. , Isaac Phillip S. , Werry Jason L.
Published: January 2013

We construct explicit formulae for the eigenvalues of certain invariants of the Lie superalgebra gl(m|n) using characteristic identities. We discuss how such eigenvalues are related to reduced Wigner coefficients and the reduced matrix elements of generators, and thus provide a first step to a new algebraic derivation of matrix element formulae for all generators of the algebra.
Combined crossed beam and theoretical studies of the C(1D) + CH4 reaction
Authors: Leonori Francesca , Skouteris Dimitrios , Petrucci Raffaele , Casavecchia Piergiorgio , Rosi Marzio , Balucani Nadia
Published: January 2013

The reaction involving atomic carbon in its first electronically excited state 1D and methane has been investigated in crossed molecular beam experiments at a collision energy of 25.3 kJ mol−1. Electronic structure calculations of the underlying potential energy surface (PES) and Rice–Ramsperger–Kassel–Marcus (RRKM) estimates of rates and branching ratios have been performed to assist the interpretation of the experimental results. The reaction proceeds via insertion of C(1D) into one of the C–H bonds of methane leading to the formation of the intermediate HCCH3 (methylcarbene or ethylidene), which either decomposes directly into the products C2H3 + H or C2H2 + H2 or isomerizes to the more stable ethylene, which in turn dissociates into C2H3 + H or H2CC + H2. The experimental results indicate that the H-displacement and H2-elimination channels are of equal importance and that for both channels the reaction mechanism is controlled by the presence of a bound intermediate, the lifetime of which is comparable to its rotational period. On the contrary, RRKM estimates predict a very short lifetime for the insertion intermediate and the dominance of the H-displacement channel. It is concluded that the reaction C(1D) + CH4 cannot be described statistically and a dynamical treatment is necessary to understand its mechanism. Possibly, nonadiabatic effects are responsible for the discrepancies, as triplet and singlet PES of methylcarbene cross each other and intersystem crossing is possible. Similarities with the photodissociation of ethylene and with the related reactions N(2D) + CH4, O(1D) + CH4 and S(1D) + CH4 are also commented on.
Density cumulant functional theory: The DC-12 method, an improved description of the one-particle density matrix
Authors: Sokolov Alexander Yu. , Simmonett Andrew C. , Schaefer Henry F.
Published: January 2013

Density cumulant functional theory (DCFT) is a theory that, in principle, can compute energies and properties exactly without a wavefunction. To accomplish this, the energy is expressed as an exact, known functional of the one-particle density matrix and two-particle density cumulant. The correlation contribution to the one-particle density matrix is obtained from the cumulant, to eliminate redundancy in the equations. The previous formulation of DCFT introduced this relationship in an approximate way, to obtain tractable equations. In this research, it is demonstrated that the correlation contribution to the one-particle density matrix can be extracted exactly from the cumulant, with minimal computational overhead and no increase in the asymptotic cost of the theory. We present numerical results, showing the improvements resulting from this reformulation (DC-12), and offer a perturbative analysis of the new equations to compare them to their predecessors.
Hydrogen-terminated detonation nanodiamond: Impedance spectroscopy and thermal stability studies
Authors: Su Shi , Li Jiangling , Kundrát Vojtěch , Abbot Andrew M. , Ye Haitao
Published: January 2013

In this paper, we investigated the effect of hydrogen termination on the electrical properties and impedance spectra of detonation nanodiamond. The impedance spectra revealed that the hydrogen-termination process increases the electrical conductivity by four orders of magnitude at room temperature. An equivalent circuit has been proposed to correlate with the conduction mechanism. Arrhenius plot showed that there were two different activation energy levels located at 0.089 eV and 0.63 eV between 50 °C and 400 °C. The possible physical mechanism corresponding to these activation energy levels has been discussed. Hydrogen-terminated detonation nanodiamond has been further annealed at different temperatures prior to FTIR and XPS measurements in order to understand their thermal stability. The results demonstrated that the surface oxidization occurred between 100 °C and 150 °C. However, the C–H bonds could partially survive when the temperature reaches 400 °C in air.
Structural diversity of the (Na1−xKx)0.5Bi0.5TiO3 perovskite at the morphotropic phase boundary
Authors: Otoničar Mojca , Škapin Srečo D. , Jančar Boštjan , Suvorov Danilo
Published: January 2013

In-situ-heating transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses were performed on the (Na1−xKx)0.5Bi0.5TiO3 perovskite solid solution at the morphotropic phase boundary (MPB) in order to evaluate the structural contribution to the enhanced electromechanical properties of piezoelectrics. Prior to heating in the TEM, the MPB sample exhibits a lamellar domain structure and an in-phase tilting of the oxygen octahedrons, both of which are characteristic of a tetragonal structure. We found that after heating the lamellar domains do not reappear; instead, a tweed-like, nanodomain structure is established with the in-phase tilt system to a large extent preserved. The XRD measurements of the MPB samples confirmed that the original structure of the MPB material is pseudocubic. When exposed to various external fields (mechanical, electrical, or temperature), the material adjusts its crystal form and orientation to the type and direction of the field, leading to the formation of a rhombohedral crystal structure, a tetragonal one or the coexistence of both structures. These analyses reveal that the source of the enhanced electromechanical responses of piezomaterials at their MPBs is their “easily adaptable” relaxor-type character with the field-induced structural conformism.
A coarse-grained model for DNA-functionalized spherical colloids, revisited: Effective pair potential from parallel replica simulations
Authors: Theodorakis Panagiotis E. , Dellago Christoph , Kahl Gerhard
Published: January 2013

We discuss a coarse-grained model recently proposed by Starr and Sciortino [J. Phys.: Condens. Matter 18, L347 (2006)10.1088/0953-8984/18/26/L02] for spherical particles functionalized with short single DNA strands. The model incorporates two key aspects of DNA hybridization, i.e., the specificity of binding between DNA bases and the strong directionality of hydrogen bonds. Here, we calculate the effective potential between two DNA-functionalized particles of equal size using a parallel replica protocol. We find that the transition from bonded to unbonded configurations takes place at considerably lower temperatures compared to those that were originally predicted using standard simulations in the canonical ensemble. We put particular focus on DNA-decorations of tetrahedral and octahedral symmetry, as they are promising candidates for the self-assembly into a single-component diamond structure. Increasing colloid size hinders hybridization of the DNA strands, in agreement with experimental findings.
Properties of epitaxial BaTiO3 deposited on GaAs
Authors: Contreras-Guerrero R. , Veazey J. P. , Levy J. , Droopad R.
Published: January 2013

Single crystal BaTiO3 (BTO) has been grown epitaxially on GaAs using molecular beam epitaxy with a 2 unit cell SrTiO3 nucleation layer. The oxide film is lattice-matched to GaAs through an in-plane rotation of 45° relative to the (100) surface leading to c-axis orientation of the BaTiO3. X-ray diffraction confirmed the crystallinity and orientation of the oxide film with a full width half maximum of 0.58° for a 7.5 nm thick layer. Piezoresponse force microscopy was used to characterize the ferroelectric domains in the BaTiO3 layer, and a coercive voltage of 1–2 V and piezoresponse amplitude ∼5 pm/V was measured.
Vibrational and structural properties of tetramethyltin under pressure
Authors: Qin Zhen-Xing , Chen Xiao-Jia , Zhang Chao , Tang Ling-Yun , Zhong Guo-Hua , Lin Hai-Qing , Meng Yue , Mao Ho-Kwang
Published: January 2013

The vibrational and structural properties of a hydrogen-rich group IVa hydride, Sn(CH3)4, have been investigated by combining Raman spectroscopy and synchrotron x-ray diffraction measurements at room temperature and at pressures up to 49.9 GPa. Both techniques allow the obtaining of complementary information on the high-pressure behaviors and yield consistent phase transitions at 0.9 GPa for the liquid to solid and 2.8, 10.4, 20.4, and 32.6 GPa for the solid to solid. The foregoing solid phases are identified to have the orthorhombic, tetragonal, monoclinic crystal structures with space groups of Pmmm for phase I, P4/mmm for phase II, P2/m for phase III, respectively. The phases IV and V coexist with phase III, resulting in complex analysis on the possible structures. These transitions suggest the variation in the inter- and intra-molecular bonding of this compound.
State-to-state quantum dynamics of the O(3P) + NH(X3Σ−) reaction on the three lowest-lying electronic states of HNO/HON
Authors: Li Anyang , Xie Changjian , Xie Daiqian , Guo Hua
Published: January 2013

The adiabatic state-to-state dynamics of the reaction between O(3P) and NH(X3Σ−) has been investigated on three lowest-lying electronic states, namely, the X1A′, A1A″, and a3A″ states, using the recently developed global potential energy surfaces based on high level ab initio data. The reaction rate has contributions from all three states, with the largest coming from the triplet state. The rotational and vibrational degrees of freedom of the prominent NO product are highly excited, although significant differences exist in the internal state distributions of the three adiabatic channels. The reaction proceeds with a complex-forming mechanism on all three electronic states, as evidenced by resonance structures in reaction probabilities and the near forward-backward symmetry in the differential cross section. However, significant non-reactive scattering and inverted vibrational state distributions suggest substantial non-statistical behaviors.
Covariance analysis of gamma ray spectra
Authors: Trainham R. , Tinsley J.
Published: January 2013

The covariance method exploits fluctuations in signals to recover information encoded in correlations which are usually lost when signal averaging occurs. In nuclear spectroscopy it can be regarded as a generalization of the coincidence technique. The method can be used to extract signal from uncorrelated noise, to separate overlapping spectral peaks, to identify escape peaks, to reconstruct spectra from Compton continua, and to generate secondary spectral fingerprints. We discuss a few statistical considerations of the covariance method and present experimental examples of its use in gamma spectroscopy.
The interaction of two nonplanar solitary waves in electron-positron-ion plasmas: An application in active galactic nuclei
Authors: EL-Labany S. K. , EL-Shamy E. F. , Sabry R. , Khedr D. M.
Published: January 2013

In the present research paper, the effect of bounded nonplanar (cylindrical and spherical) geometry on the interaction between two nonplanar electrostatic solitary waves (NESWs) in electron–positron–ion plasmas has been studied. The extended Poincaré–Lighthill–Kuo method is used to obtain nonplanar phase shifts after the interaction of the two NESWs. This study is a first attempt to investigate nonplanar phase shifts and trajectories for NESWs in a two-fluid plasma (a pair-plasma) consisting of electrons and positrons, as well as immobile background positive ions in nonplanar geometry. The change of phase shifts and trajectories for NESWs due to the effect of cylindrical geometry, spherical geometry, the physical processes (either isothermal or adiabatic), and the positions of two NESWs are discussed. The present investigation may be beneficial to understand the interaction between two NESWs that may occur in active galactic nuclei.
Determination and correction of distortions and systematic errors in low-energy electron diffraction
Authors: Sojka Falko , Meissner Matthias , Zwick Christian , Forker Roman , Fritz Torsten
Published: January 2013

We developed and implemented an algorithm to determine and correct systematic distortions in low-energy electron diffraction (LEED) images. The procedure is in principle independent of the design of the apparatus (spherical or planar phosphorescent screen vs. channeltron detector) and is therefore applicable to all device variants, known as conventional LEED, micro-channel plate LEED, and spot profile analysis LEED. The essential prerequisite is a calibration image of a sample with a well-known structure and a suitably high number of diffraction spots, e.g., a Si(111)-7×7 reconstructed surface. The algorithm provides a formalism which can be used to rectify all further measurements generated with the same device. In detail, one needs to distinguish between radial and asymmetric distortion. Additionally, it is necessary to know the primary energy of the electrons precisely to derive accurate lattice constants. Often, there will be a deviation between the true kinetic energy and the value set in the LEED control. Here, we introduce a method to determine this energy error more accurately than in previous studies. Following the correction of the systematic errors, a relative accuracy of better than 1% can be achieved for the determination of the lattice parameters of unknown samples.
Carbon nanowalls grown by microwave plasma enhanced chemical vapor deposition during the carbonization of polyacrylonitrile fibers
Authors: Li Jiangling , Su Shi , Zhou Lei , Kundrát Vojtěch , Abbot Andrew M. , Mushtaq Fajer , Ouyang Defang , James David , Roberts Darren , Ye Haitao
Published: January 2013

We used microwave plasma enhanced chemical vapor deposition (MPECVD) to carbonize an electrospun polyacrylonitrile (PAN) precursor to form carbon fibers. Scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the fibers at different evolution stages. It was found that MPECVD-carbonized PAN fibers do not exhibit any significant change in the fiber diameter, whilst conventionally carbonized PAN fibers show a 33% reduction in the fiber diameter. An additional coating of carbon nanowalls (CNWs) was formed on the surface of the carbonized PAN fibers during the MPECVD process without the assistance of any metallic catalysts. The result presented here may have a potential to develop a novel, economical, and straightforward approach towards the mass production of carbon fibrous materials containing CNWs.
Experimental verification of intermediate band formation on titanium-implanted silicon
Authors: Castán H. , Pérez E. , García H. , Dueñas S. , Bailón L. , Olea J. , Pastor D. , García-Hemme E. , Irigoyen M. , González-Díaz G.
Published: January 2013

Intermediate band formation on silicon layers for solar cell applications was achieved by titanium implantation and laser annealing. A two-layer heterogeneous system, formed by the implanted layer and by the un-implanted substrate, was formed. In this work, we present for the first time electrical characterization results which show that recombination is suppressed when the Ti concentration is high enough to overcome the Mott limit, in agreement with the intermediate band theory. Clear differences have been observed between samples implanted with doses under or over the Mott limit. Samples implanted under the Mott limit have capacitance values much lower than the un-implanted ones as corresponds to a highly doped semiconductor Schottky junction. However, when the Mott limit is surpassed, the samples have much higher capacitance, revealing that the intermediate band is formed. The capacitance increasing is due to the big amount of charge trapped at the intermediate band, even at low temperatures. Ti deep levels have been measured by admittance spectroscopy. These deep levels are located at energies which vary from 0.20 to 0.28 eV below the conduction band for implantation doses in the range 1013-1014 at./cm2. For doses over the Mott limit, the implanted atoms become nonrecombinant. Capacitance voltage transient technique measurements prove that the fabricated devices consist of two-layers, in which the implanted layer and the substrate behave as an n+/n junction.
Graphene–Fe3O4 nanohybrids: Synthesis and excellent electromagnetic absorption properties
Authors: Wang Tieshi , Liu Zhaohong , Lu Mingming , Wen Bo , Ouyang Qiuyun , Chen Yujin , Zhu Chunling , Gao Peng , Li Chunyan , Cao Maosheng , Qi Lihong
Published: January 2013

Graphene (G)–Fe3O4 nanohybrids were fabricated by first depositing β-FeOOH crystals with diameter of 3–5 nm on the surface of the graphene sheets. After annealing under Ar flow, β-FeOOH nanocrystals were reduced to Fe3O4 nanoparticles by the graphene sheets, and thus G–Fe3O4 nanohybrids were obtained. The Fe3O4 nanoparticles with a diameter of about 25 nm were uniformly dispersed over the surface of the graphene sheets. Moreover, compared with other magnetic materials and the graphene, the nanohybrids exhibited significantly increased electromagnetic absorption properties owing to high surface areas, interfacial polarizations, and good separation of magnetic nanoparticles. The maximum reflection loss was up to −40.36 dB for G–Fe3O4 nanohybrids with a thickness of 5.0 mm. The nanohybrids are very promising for lightweight and strong electromagnetic attenuation materials.
Nanotube wall thickness dependent magnetization reversal properties of NiFe nanotubes
Authors: Sharif R. , Shamaila S. , Shaheen F. , Naseem S. , Chen J. Y. , Khaleeq-ur-Rahman M. , Hussain K. , Han X. F.
Published: January 2013

Nanotube wall thickness dependent magnetization properties of NiFe nanotube arrays electrodeposited in polycarbonate membranes are investigated. A systematic variation of nanotube wall thickness (tw) has been investigated. The magnetization reversal properties are strongly influenced by the variation of tw keeping length and external radius constant.
Efficient n-type doping of Si nanocrystals embedded in SiO2 by ion beam synthesis
Authors: Khelifi Rim , Mathiot Daniel , Gupta Raghav , Muller Dominique , Roussel Manuel , Duguay Sébastien
Published: January 2013

It is shown that co-implantation, with overlapping projected ranges of Si and P or As, followed by a single thermal annealing step is an efficient way to form doped Si nanocrystals (Si-nc's) embedded in SiO2 with diameters of a few nanometers. Atom probe tomography is used to image directly the spatial distribution of the various species at the atomic scale, evidencing that the P and As atoms are efficiently introduced inside the Si nanocrystals. In addition, we report on the influence of the dopant doses on the Si-nc's related photoluminescence as well as on the I(V) characteristics of MOS structures including these Si-nc's.
Electronic structure tuning of diamondoids through functionalization
Authors: Rander Torbjörn , Staiger Matthias , Richter Robert , Zimmermann Tobias , Landt Lasse , Wolter David , Dahl Jeremy E. , Carlson Robert M. K. , Tkachenko Boryslav A. , Fokina Natalie A. , Schreiner Peter R. , Möller Thomas , Bostedt Christoph
Published: January 2013

We investigated the changes in electronic structures induced by chemical functionalization of the five smallest diamondoids using valence photoelectron spectroscopy. Through the variation of three parameters, namely functional group (thiol, hydroxy, and amino), host cluster size (adamantane, diamantane, triamantane, [121]tetramantane, and [1(2,3)4]pentamantane), and functionalization site (apical and medial) we are able to determine to what degree these affect the electronic structures of the overall systems. We show that unlike, for example, in the case of halobenzenes, the ionization potential does not show a linear dependence on the electronegativity of the functional group. Instead, a linear correlation exists between the HOMO-1 ionization potential and the functional group electronegativity. This is due to localization of the HOMO on the functional group and the HOMO-1 on the diamondoid cage. Density functional theory supports our interpretations.
Influence of stress on structural properties of AlGaN/GaN high electron mobility transistor layers grown on 150 mm diameter Si (111) substrate
Authors: Liu H. F. , Dolmanan S. B. , Zhang L. , Chua S. J. , Chi D. Z. , Heuken M. , Tripathy S.
Published: January 2013

Effects of stress imposed by individual nitride layers on structural properties of an AlGaN/GaN high-electron-mobility-transistor (HEMT) structure, which was grown on a 150 mm diameter Si (111) substrate by metal-organic chemical vapor deposition employing high-temperature step-graded AlxGa1−xN/AlN buffer layers, were studied using transmission electron microscopy, visible micro-Raman spectroscopy, and high-resolution x-ray diffraction. It is revealed that all the nitride layers are more or less tensile strained on the Si (111) substrate; however, strain relaxations occurred at all the heterointerfaces except for the AlGaN/(AlN/)GaN two-dimensional electron gas interface, which is desired for achieving high performance HEMT. The wafer curvature, an important parameter for large area epitaxy of GaN-on-Si, is modeled on the basis of stress distribution within individual layers of the multilayered AlGaN/GaN HEMT structure via the close-form expression developed by Olsen and Ettenberg [J. Appl. Phys. 48, 2543 (1977)]. The evolution of wafer curvature induced by substrate thinning and stress redistribution is predicted by this model, which is further qualitatively confirmed by experimental results.
Optical gain analysis of c-InGaN quantum wells on unstrained c-In0.31Ga0.69N templates
Authors: Kotani Teruhisa , Lugli Paolo , Hamaguchi Chihiro
Published: January 2013

We investigate the optical properties of c-InxGa1−xN (x = 0.31–0.44) quantum wells (QWs) on unstrained c-In0.31Ga0.69N templates in the green-to-red spectral range using self-consistent multiband k·p theory. The transverse-electric- and transverse-magnetic-polarized optical gains are much higher for QWs on unstrained c-In0.31Ga0.69N templates compared with conventional templates because of a smaller internal electric field and strong valence band mixing. Using c-InxGa1−xN QWs on c-In0.31Ga0.69N templates is expected to reduce the threshold carrier density in the green range and extend the operable wavelength into the red range.
An ultrathin but nearly perfect direct current electric cloak
Authors: Xiang Jiang Wei , Yang Luo Chen , Lei Mei Zhong , Jun Cui Tie
Published: January 2013

We propose and experimentally demonstrate an ultrathin but nearly perfect dc electric invisibility cloak. In the dc limit, transformation optics reduces to transformation electrostatics. Based on a special coordinate transformation, we derive a nearly perfect dc electric cloak which is composed of homogeneous and anisotropic conducting material. Due to the homogeneity feature, the dc cloak is realized using an ultrathin dc metamaterial with only one-unit-cell thickness, which is the ultra limit for practical artificial materials. Although ultrathin, our experimental results show that the dc cloak has excellent performance with nearly perfect cloaking behaviour.
Role of nitrogen in AlNxMn3: A density functional theory study
Authors: Shao D. F. , Lu W. J. , Lin J. C. , Tong P. , Jian H. B. , Sun Y. P.
Published: January 2013

Recently, we successfully synthesized the nitrogen-deficient manganese antiperovskites AlNxMn3 with the very high ferromagnetic Curie temperatures TC up to 818 K [Lin et al., Appl. Phys. Lett. 98, 092507 (2011)]. In order to figure out the role of nitrogen for the magnetism, in the present work, we performed a theoretical investigation on AlNxMn3 through the first-principles calculation based on density functional theory. The results show that AlNxMn3 have the ferromagnetic ground states, and the total magnetic moments in a cell are enhanced with decreasing the nitrogen concentration. Based on the calculations of band structure and density of states, we showed the influence of nitrogen concentration on magnetism for AlNxMn3: The decreasing of nitrogen concentration from ideal AlNMn3 moves the spin-down bands towards the high energy remarkably, which enhances the exchange splitting energy ΔEex; on the other hand, nitrogen deficiency reduces the Mn-N hybridizations, which makes the 3d electrons of Mn tend to occupy the spin-up states. The nitrogen deficiency reduces the Mn-N hybridization, which narrows Mn-d bands and enhances the spin polarization. Furthermore, we estimated TC of AlNxMn3, and found the calculated TC can be scaled by spin fluctuation temperature TSF, suggesting AlNxMn3 belong to the spin fluctuation system.
Experimental investigation of the visibility dependence in a nonlinear interferometer using parametric amplifiers
Authors: Kong Jia , Jing Jietai , Wang Hailong , Hudelist F. , Liu Cunjin , Zhang Weiping
Published: January 2013

Two four-wave mixing processes have been employed to experimentally construct a nonlinear interferometer [Jing et al., Appl. Phys. Lett. 99, 011110 (2011)], which has a better phase sensitivity than the traditional linear interferometer. For its applications in quantum measurement, interference fringe visibility can significantly affect the quantum detection efficiency. In this letter, we study how various parameters, such as the pump power, the one-photon detuning, and the two-photon detuning, influence the visibility of nonlinear interferometer. We find that the visibility greater than 0.9 can be achieved for large range of system parameters.
Detection of electrically formed photosensitive area in Ca-doped BiFeO3 thin films
Authors: Kamala Bharathi K. , Lee Won-Mo , Ho Sung Ji , Soo Lim Ji , Jin Kim Seung , Chu Kanghyun , Won Park Jung , Hyun Song Jong , Jo Moon-Ho , Yang Chan-Ho
Published: January 2013

We report on the visualization of n-p junctions formed by oxygen vacancy movement under the application of an electric field in a Ca-doped BiFeO3 thin film through spatially resolved scanning photocurrent mapping. The photocurrent mapping, in conjunction with the spectroscopic approach, provides clues to local electronic structures and defect levels associated with oxygen vacancies. These observations provide insights into the spatial redistribution of oxygen vacancies in an electric field.
Electron and ion thermal forces in complex (dusty) plasmas
Authors: Khrapak Sergey A.
Published: January 2013

Expressions for the ion and electron thermal forces acting on a charged grain, suspended in a weakly ionized plasma subject to temperature gradients, are derived. The main emphasize is on the conditions pertinent to the investigations of complex (dusty) plasmas in gas discharges. Estimates show that for the electron temperature gradients ∼O(eV/cm) typically encountered in laboratory gas discharges, the electron thermal force can become an important player among other forces acting on micron-size grains.
Linear properties of energetic particle driven geodesic acoustic mode
Authors: Wang Hao , Todo Yasushi
Published: January 2013

Linear properties of energetic particle driven geodesic acoustic mode (EGAM) in the large helical device plasmas are investigated using a hybrid simulation code for a magnetohydrodynamics fluid interacting with energetic particles. It is found that the EGAM is a global mode with the spatially uniform oscillation frequency despite the spatial variation of the local geodesic acoustic mode frequency. The poloidal mode numbers of poloidal velocity fluctuation, plasma density fluctuation, and magnetic fluctuation are m = 0, 1, and 2, respectively. Oscillation frequency, linear growth rate, and spatial width of EGAM are compared for different physics conditions. The EGAM frequency is proportional to the square root of the plasma temperature. The frequency is lower for higher energetic particle β value. The mode spatial width is larger for larger spatial width of the energetic particle distribution and for the reversed shear safety-factor profile than the normal shear profile. It is also found that the EGAM propagates radially outward in the linearly growing phase, and the propagation speed is slower for the spatially broadened modes.
Regular subspaces of a quaternionic Hilbert space from quaternionic Hermite polynomials and associated coherent states
Authors: Thirulogasanthar K. , Ali S. Twareque
Published: January 2013

We define quaternionic Hermite polynomials by analogy with two families of complex Hermite polynomials. As in the complex case, these polynomials constitute orthogonal families of vectors in ambient quaternionic L2-spaces. Using these polynomials, we then define regular and anti-regular subspaces of these L2-spaces, the associated reproducing kernels and the ensuing quaternionic coherent states.
Klystron-like cavity with mode transformation for high-harmonic terahertz gyrotrons
Authors: Bandurkin I. V. , Kalynov Yu. K. , Savilov A. V.
Published: January 2013

A novel cavity scheme of a gyrotron is proposed and investigated. As it provides low Ohmic losses and high mode selectivity, it can be especially prospective for realization in gyrotrons operating in the THz frequency range. Numerical simulations show that it allows three-fold increase in the efficiency of the low-relativistic 500 GHz fourth-harmonic gyrotron as compared to conventional two-section scheme with modes transformation.
Electrostatic supersolitons in three-species plasmas
Authors: Verheest Frank , Hellberg Manfred A. , Kourakis Ioannis
Published: January 2013

Superficially, electrostatic potential profiles of supersolitons look like those of traditional solitons. However, their electric field profiles are markedly different, having additional extrema on the wings of the standard bipolar structure. This new concept was recently pointed out in the literature for a plasma model with five species. Here, it is shown that electrostatic supersolitons are not an artefact of exotic, complicated plasma models, but can exist even in three-species plasmas and are likely to occur in space plasmas. Further, a methodology is given to delineate their existence domains in a systematic fashion by determining the specific limiting factors.
Reverse boundary layer capacitor model in glass/ceramic composites for energy storage applications
Authors: Wei Xiaoyong , Yan Haixue , Wang Tong , Hu Qingyuan , Viola G. , Grasso Salvatore , Jiang Qinghui , Jin Li , Xu Zhuo , Reece Michael J.
Published: January 2013

Reverse boundary layer capacitor (RBLC) configuration model, where the grain boundary has a higher electrical conductivity than the grain, is proposed in glass/ceramic composites for dielectric energy storage applications. By introducing glass additives as grain boundaries with electrical conductivity higher than ceramic grains, the steady electric field across grains can be larger than grain boundaries as desired due to the conductivity difference. The breakdown field is thus expected to increase in the RBLC-type brick wall model because of the field distribution. The equivalent circuit, grain boundary conductivity dependence of energy density, low-loss frequency range of the RBLC model are discussed. The simulation results suggest that the RBLC approach has advantages in overall energy density, compared with normal insulating glass phase composites.
Note: Gliding arc discharges with phase-chopped voltage supply for enhancement of energy efficiency in volatile organic compound decomposition
Authors: Bo Zheng , Wu Erka , Yan Jianhua , Chi Yong , Cen Kefa
Published: January 2013

This note reports on a novel power supply design for gliding arc discharge with applying controlled phase-chopping on the input voltage waveform, aiming at simultaneously satisfying the decomposition efficacy and energy efficiency for volatile organic compound decomposition. With a proper control on the phase-chopping fraction, the energy efficiency can be obviously enhanced, while the decomposition efficacy is almost maintained, possibly due to the compensation from long-life radical induced decomposition during discharge intervals.
Sexual reproduction and mating-type–mediated strain development in the penicillin-producing fungus
Penicillium chrysogenum
Authors: Böhm Julia , Hoff Birgit , O’Gorman Céline M. , Wolfers Simon , Klix Volker , Binger Danielle , Zadra Ivo , Kürnsteiner Hubert , Pöggeler Stefanie , Dyer Paul S. , Kück Ulrich
Published: January 2013

Penicillium chrysogenum
is a filamentous fungus of major medical and historical importance, being the original and present-day industrial source of the antibiotic penicillin. The species has been considered asexual for more than 100 y, and despite concerted efforts, it has not been possible to induce sexual reproduction, which has prevented sexual crosses being used for strain improvement. However, using knowledge of mating-type (
MAT
) gene organization, we now describe conditions under which a sexual cycle can be induced leading to production of meiotic ascospores. Evidence of recombination was obtained using both molecular and phenotypic markers. The identified heterothallic sexual cycle was used for strain development purposes, generating offspring with novel combinations of traits relevant to penicillin production. Furthermore, the
MAT1-1–1
mating-type gene, known primarily for a role in governing sexual identity, was also found to control transcription of a wide range of genes with biotechnological relevance including those regulating penicillin production, hyphal morphology, and conidial formation. These discoveries of a sexual cycle and
MAT
gene function are likely to be of broad relevance for manipulation of other asexual fungi of economic importance.
Age‐related differences in everyday prospective memory tasks: The role of planning and personal importance
Authors: Niedźwieńska Agnieszka , Janik Beata , Jarczyńska Aleksandra
Published: January 2013

The aim of the present studies was to investigate whether age‐related improvement found in naturalistic but experimenter‐given prospective memory (PM) tasks can be generalized to real‐life intentions. In Study 1, younger, middle‐aged, and older adults generated a list of intended activities for the following week; one week later they marked the tasks that they had performed. The participants were also asked to rate the importance of each listed intention and to describe the circumstances of completion that were already known to them. We found that, compared with younger adults, older adults attributed a higher degree of importance to their intentions and had the circumstances of their completion better planned. However, the age‐related benefit in the PM performance for all listed intentions was not present for the very important and well‐planned tasks. In Study 2 we manipulated whether younger adults engaged or not in the detailed planning of when their intentions could be completed. It was demonstrated that younger adults who had to perform detailed planning completed their intended activities more often than those who did not plan for their intentions. The results support explanations of the age‐related benefit in everyday PM that highlight the role of importance and planning.
Alcohol and Drug Use, Smoking, and Gambling among Psychiatric Outpatients: A 1-Year Prevalence Study
Authors: Nehlin Christina , Grönbladh Leif , Fredriksson Anders , Jansson Lennart
Published: January 2013

Background and Aims: Studies of alcohol habits in general psychiatric populations are scarce. The objective was to investigate alcohol and drug use, smoking, and gambling in a clinical sample of psychiatric outpatients. A further aim was to study age and gender differences in the rates of these habits. Methods: Data were collected among psychiatric outpatients with mainly mood (47%) and anxiety (35%) disorders. A questionnaire package was distributed, including AUDIT (Alcohol Use Disorders Identification Test), DUDIT (Drug Use Disorders Identification Test), tobacco items, and gambling items. Two major drinking categories were formed: “Nonhazardous alcohol use” (NH) and “Alcohol use above hazardous levels” (AH). Results: In total, 2160 patients (65% females) responded to the questionnaire package. The AH rate was high among psychiatric outpatients (28.4%), particularly among young females (46.6%). Young female patients also reported a high prevalence of problematic drug use (13.8%). Problematic drug use, daily smoking, and problematic gambling were frequent. The unhealthy habits were linked to AH. Conclusions: Alcohol and drug use, smoking, and gambling are all highly prevalent among psychiatric outpatients. Young females are in particular need of attention. Interventions should be tailored for co-occurring psychiatric disorders and applied within routine psychiatric care.
Meeting needs of Muslim girls in school sport: Case studies exploring cultural and religious diversity
Authors: Benn Tansin , Pfister Gertrud
Published: January 2013

This paper contains a sociocultural analysis of school sport experiences of Muslim girls in two countries with different gender policies in physical education (PE) classes: England and Denmark. In Denmark, PE lessons take place in co‐educative classes, in England schools are more diverse, with predominantly co‐educational but also single‐sex and faith schools offering different learning contexts. Two case studies from Denmark and England are used to explore the experiences of migrant Muslim girls in these different settings. A social constructionist approach to gender underpins the interpretation of stakeholders' voices on the inclusion of Muslim girls and the analysis of PE discourses in these countries. Findings illustrate similarities and differences at the interface of cultural diversity, political rhetoric of inclusion and realities of sport experiences for Muslim girls in both countries. Complex influences on PE experiences include gender stereotypes, cultural and religious orientations and practices, as well as actions and expectations of parents, communities and coaches/teachers. The studies provide insights into the ways participants managed their identities as Muslim girls in different sport environments to enable participation and retention of their cultural identities. Highlighted throughout the paper are the ways in which school sport policy and practice, providers and gatekeepers, can include or exclude groups, in this case Muslim girls. Too often coaches and teachers are unaware of crucial facts about their learners, not only in terms of their physical development and capabilities but also in terms of their cultural needs. Mistakes in creating conducive learning environments leave young people to negotiate a way to participate or refrain from participation.