bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the first blastomeres in Coho salmon (Oncorhynchus kisutch)
Authors: Roldán Brian Effer , Rueda Rubén Sánchez , Madrid Andrea Ubilla , Villalobos Elías Figueroa , Isler Iván Valdebenito
Published: July 2012

There is a lack of information on the morphology of the first blastomeres that could be used as a diagnostic tool for the first stages of embryonic development for Coho salmon. The purpose of this investigation, therefore, was to characterize morphometrically the first blastomeres of Coho salmon (Oncorhynchus kisutch). In total, 660 embryonic discs from a pool of eggs that had been fertilized and incubated at 5°C and after 19 h of incubation were extracted and photographed. Of these, 20 microphotographs of blastodiscs of normal appearance were analyzed morphologically (control blastodiscs: CB) and 100 random microphotographs from the whole group were classified as either symmetrical or asymmetrical according to their morphology and then compared with the CB. The length and width of each blastomere and the proportions of length and width were measured to determine symmetry in the embryos at the 4-cell stage. Seven categories were created to characterize the blastomeres: 38% normal (G1); 26% unequal (G2); 10% ‘pie-shaped’ (G3); 10% amorphous (G4); 8% with three equal and one unequal blastomere (G5); 6% ‘clover-shaped’ blastomeres (G7), and 3% with inclusions. The mean of the proportions of lengths and widths of the groups of blastomeres that were measured was 0.87 ± 0.08 and 0.85 ± 0.07, respectively. The morphometric results that were obtained in this investigation are compared with the results observed by other authors for teleostei and are discussed.
CARNAP ON EXTREMAL AXIOMS, “COMPLETENESS OF THE MODELS,” AND CATEGORICITY
Authors: SCHIEMER GEORG
Published: July 2012

This paper provides a historically sensitive discussion of Carnap’s theory of extremal axioms developed first in the late 1920s. The main focus is set on the unpublished documents of the projected second part of his manuscriptUntersuchungen zur allgemeinen Axiomatik(RC 081-01-01 to 081-01-33). Carnap’s theory will be assessed with respect to two interpretive issues. The first concerns his mathematical sources, that is, the mathematical axioms on which his extremal axioms were based. The second concerns Carnap’s understanding of the relationship between the “completeness of the models” and other metatheoretic notions investigated by him at the time, most notably that of categoricity. The paper surveys Carnap’s different attempts to explicate the extremal properties of a theory and puts his results in context with related metamathematical research at the time.
China and the “Responsibility to Protect”: The Implications of the Libyan Intervention
Authors: GARWOOD-GOWERS Andrew
Published: July 2012

The emerging principle of the “responsibility to protect” (R2P) challenges China's traditional emphasis on non-intervention in the domestic affairs of other states and non-use of force. This article considers the impact of the 2011 Libyan intervention on Beijing's evolving relationship with R2P, and assesses its implications for the future development of the doctrine itself. It argues that China's decision to allow the passage of Security Council resolution 1973, which authorized force in Libya, was shaped by an unusual set of political and factual circumstances, and does not represent a significant softening of Chinese attitudes towards R2P. More broadly, controversy over the scope of NATO's military action in Libya has raised questions about R2P's legitimacy, which have contributed to a lack of timely international action in Syria. In the short term, this post-Libya backlash against R2P is likely to constrain the Security Council's ability to respond decisively in civilian protection situations.
Necessity of substorm expansions in the initiation of steady magnetospheric convection
Authors: Kissinger J. , McPherron R. L. , Hsu T.‐S. , Angelopoulos V. , Chu X.
Published: July 2012

Steady magnetospheric convection (SMC) events occur during enhanced solar wind driving of the magnetosphere and are characterized by quasi‐stable convection, without any substorm expansions, for several hours. Previous research has hinted that a substorm onset may be required before the magnetosphere can enter the SMC mode of response. For the first time, we show statistically that nearly all SMC events are preceded by a substorm. Only 1% of SMC events occur without any preceding substorm signatures. The typical magnetospheric reaction to enhanced solar wind driving is a substorm. After this occurs, we find that the duration and stability of southward IMF determines whether a particular substorm will transition into an SMC event or not. The initial substorm sets up a high pressure region in the inner magnetosphere that causes flux diversion to the flanks, which allows closed flux from the nightside x‐line to return to balance the dayside reconnection rate.
Air‐water CO2 fluxes in the microtidal Neuse River Estuary, North Carolina
Authors: Crosswell Joseph R. , Wetz Michael S. , Hales Burke , Paerl Hans W.
Published: July 2012

From June 2009 to July 2010, we conducted 27 continuous‐flow surveys of surface water CO2 partial pressure (pCO2) along the longitudinal axis of the Neuse River Estuary (NRE), North Carolina ranging from the tidal freshwater region to the polyhaline border with the Pamlico Sound. Lateral transects were also conducted at the borders of each of three hydrologically distinct sections. The pCO2 displayed considerable spatial‐temporal variability. Likewise, net air‐water CO2 fluxes showed high spatial and temporal variability, with a maximum [release] of 271 mmol C m−2 d−1 during high river flow conditions in fall and minimum [uptake] of −38 mmol C m−2 d−1 during wind‐driven, high primary productivity conditions in late spring. During high‐flow conditions, pCO2 generally decreased from the river mouth to the Pamlico Sound, similar to patterns seen in well‐mixed systems. During warm, low‐flow conditions, surface water pCO2 distributions were spatially variable and dissimilar to those patterns seen in most macrotidal, well‐mixed estuaries. The annual air‐water CO2 efflux from the study area was 4.7 mol C m−2 yr−1, an order of magnitude less than previously estimated for temperate estuaries. The CO2 fluxes observed in the NRE highlight the contrasts between macrotidal and microtidal systems and suggest that global estuarine CO2 emissions are likely overestimated by the current classification approaches. Scaling this lower efflux by the relative surface area of macrotidal and microtidal systems would reduce the global estuarine flux by 42%.
On discriminating swell and wind‐driven seas in Voluntary Observing Ship data
Authors: Badulin S. I. , Grigorieva V. G.
Published: July 2012

The global visual wave observations are reanalyzed within the theoretical concept of self‐similar wind‐driven seas. The core of the analysis is one‐parametric dependencies of wave height on wave period. Theoretically, wind‐driven seas are governed by power‐like laws with exponents close to Toba's one 3/2 while the corresponding swell exponent (−1/2) has an opposite signature. This simple criterion was used and appeared to be adequate to the problem of swell and wind‐driven waves discrimination. This theoretically based discrimination does not follow exactly the Voluntary Observing Ship (VOS) data. This important issue is considered both in the context of methodology of obtaining VOS data and within the physics of wind waves. The results are detailed for global estimates and for analysis of particular areas of the Pacific Ocean. Prospects of further studies are discussed. In particular, satellite data are seen to be promising for tracking ocean swell and for studies of physical mechanisms of its evolution.
Laboratory experiments on crater scaling‐law for sedimentary rocks in the strength regime
Authors: Suzuki A. , Hakura S. , Hamura T. , Hattori M. , Hayama R. , Ikeda T. , Kusuno H. , Kuwahara H. , Muto Y. , Nagaki K. , Niimi R. , Ogata Y. , Okamoto T. , Sasamori T. , Sekigawa C. , Yoshihara T. , Hasegawa S. , Kurosawa K. , Kadono T. , Nakamura A. M. , Sugita S. , Arakawa M.
Published: July 2012

We systematically conducted impact cratering experiments with sedimentary rocks at 0.8–7.1 km/s using various projectiles with 1.1–15 g/cm3in density. The crater diameter, depth, and volume are investigated and compared with the results for igneous rocks. Then, using the non‐dimensional parameters, the normalized crater diameterπD, the normalized depth πd, the normalized volume πV, the target strength per specific energy π3, and the target and projectile density ratio π4, the scaling laws, πD = (1.43 ± 0.25)π3−0.22±0.02 π40.11±0.07, πd = (0.22 ± 0.04)π3−0.25±0.02 π40.01±0.05, and πV = (0.11 ± 0.04) π3−0.71±0.05 π40.23±0.17, are obtained. The comparison with the results of igneous rocks suggests that the characteristic properties of sedimentary rocks such as the lower strength and the strong shock wave attenuation rate are actually effective for the cratering of sedimentary rocks.
Albumin Therapy Enhances Collateral Perfusion after Laser-Induced Middle Cerebral Artery Branch Occlusion: A Laser Speckle Contrast Flow Study
Authors: DeFazio Richard A , Zhao Weizhao , Deng Xiaolu , Obenaus Andre , Ginsberg Myron D
Published: July 2012

Laser speckle contrast (LSC) was used to compare the extent of cortical ischemia in two inbred mouse strains that differed in their degree of collateral circulation, after laser occlusion of the distal middle cerebral artery, and after treatment with 25% albumin (ALB) or saline (control). Sequential LSC images acquired over ~90 minutes were coaligned, converted to relative flow, and normalized to baseline. After 3-day survival, infarction was quantified by triphenyl tetrazolium chloride or magnetic resonance imaging. In the sparsely collateralized BALB/c strain, mean flow fell to 13% to 14% and 33% to 34% of baseline in central (core) and peripheral (penumbral) regions of interest, and ALB treatment at 30 minutes enhanced perfusion in both regions by ~2-fold relative to saline, restoring flow to the benign-oligemic range centrally, and to the hyperemic range peripherally. The ALB-induced increment in parenchymal perfusion was disproportionate to the subtle flow increase in the occluded artery itself, suggesting that ALB improved collateral circulation. Cortical infarction in BALB/c mice was reduced 45% by ALB treatment. In contrast to BALB/c mice, the better-collateralized CD-1 strain developed milder ischemia, had smaller infarcts, and showed no differential benefit of ALB. We conclude that where native collateralization is insufficient (BALB/c strain), ALB treatment exerts a significant therapeutic effect after ischemia by augmenting collateral perfusion.
MRI Measurement of Angiogenesis and the Therapeutic Effect of Acute Marrow Stromal Cell Administration on Traumatic Brain Injury
Authors: Li Lian , Chopp Michael , Ding Guang Liang , Qu Chang Sheng , Li Qing Jiang , Lu Mei , Wang Shiyang , Nejad-Davarani Siamak P , Mahmood Asim , Jiang Quan
Published: July 2012

Using magnetic resonance imaging (MRI), the present study was undertaken to investigate the therapeutic effect of acute administration of human bone marrow stromal cells (hMSCs) on traumatic brain injury (TBI) and to measure the temporal profile of angiogenesis after the injury with or without cell intervention. Male Wistar rats (300 to 350 g, n = 18) subjected to controlled cortical impact TBI were intravenously injected with 1 mL of saline ( n = 9) or hMSCs in suspension ( n = 9, 3 × 106 hMSCs) 6 hours after TBI. In-vivo MRI acquisitions of T2-weighted imaging, cerebral blood flow (CBF), three-dimensional (3D) gradient echo imaging, and blood-to-brain transfer constant (Ki) of contrast agent were performed on all animals 2 days after injury and weekly for 6 weeks. Sensorimotor function and spatial learning were evaluated. Volumetric changes in the trauma-induced brain lesion and the lateral ventricles were tracked and quantified using T2 maps, and hemodynamic alteration and blood–brain barrier permeability were monitored by CBF and Ki, respectively. Our data show that transplantation of hMSCs 6 hours after TBI leads to reduced cerebral atrophy, early and enhanced cerebral tissue perfusion and improved functional outcome compared with controls. The hMSC treatment increases angiogenesis in the injured brain, which may promote neurologic recovery after TBI.
Surface enhanced Raman scattering and localized surface plasmon resonance of nanoscale ultrathin films prepared by atomic layer deposition
Authors: Chih Lin Ming , Nien Li-Wei , Chen Ching-Hsiang , Lee Chia-Wei , Chen Miin-Jang
Published: July 2012

An approach was proposed to characterize nanoscale ultrathin films using surface enhanced Raman scattering (SERS). Raman spectroscopy of the TiO2 film as thin as ∼2 nm, which was prepared by atomic layer deposition, was obtained by depositing a nanostructured Au layer on the film surface. Red-shift in the extinction spectrum of the nanostructured Au layer was observed with increasing TiO2 film thickness, ascribed to the increase in effective refractive index of the substrate slab and coupled plasmon resonance. This SERS technique can be applied to investigate a variety of solid-state ultrathin films in nanosclae materials and devices in future studies.
Spatial heterodyne Stokes vector imaging of the motional Stark-Zeeman multiplet
Authors: Howard John , Chung Jinil
Published: July 2012

We present a general Stokes interferometer/polarimeter suitable for polarimetric imaging the elliptically polarized motional Stark-Zeeman multiplet. We also introduce a fully phase-heterodyne spatial multiplex variant of the system that has been used for imaging of Balmer alpha emission from the heating neutral beam in the KSTAR super-conducting tokamak in Korea. The polarimeter performance is illustrated using various polarization test targets.
Molecular structure calculations: A unified quantum mechanical description of electrons and nuclei using explicitly correlated Gaussian functions and the global vector representation
Authors: Mátyus Edit , Reiher Markus
Published: July 2012

We elaborate on the theory for the variational solution of the Schrödinger equation of small atomic and molecular systems without relying on the Born–Oppenheimer paradigm. The all-particle Schrödinger equation is solved in a numerical procedure using the variational principle, Cartesian coordinates, parameterized explicitly correlated Gaussian functions with polynomial prefactors, and the global vector representation. As a result, non-relativistic energy levels and wave functions of few-particle systems can be obtained for various angular momentum, parity, and spin quantum numbers. A stochastic variational optimization of the basis function parameters facilitates the calculation of accurate energies and wave functions for the ground and some excited rotational-(vibrational-)electronic states of \documentclass[12pt]{minimal}\begin{document}${\rm H}_2^+$\end{document}H2+ and H2, three bound states of the positronium molecule, Ps2, and the ground and two excited states of the 7Li atom.
Nonlinear propagation of coherent electromagnetic waves in a dense magnetized plasma
Authors: Shukla P. K. , Eliasson B. , Stenflo L.
Published: July 2012

We present an investigation of the nonlinear propagation of high-frequency coherent electromagnetic waves in a uniform quantum magnetoplasma. Specifically, we consider nonlinear couplings of right-hand circularly polarized electromagnetic-electron-cyclotron (CPEM-EC) waves with dispersive shear Alfvén (DSA) and dispersive compressional Alfvén (DCA) perturbations in plasmas composed of degenerate electron fluids and non-degenerate ion fluids. Such interactions lead to amplitude modulation of the CPEM-EC wave packets, the dynamics of which is governed by a three-dimensional nonlinear Schrödinger equation (NLSE) with the frequency shift arising from the relativistic electron mass increase in the CPEM-EC fields and density perturbations associated with the DSA and DCA perturbations. Accounting for the electromagnetic and quantum forces, we derive the evolution equation for the DSA and DCA waves in the presence of the magnetic field-aligned ponderomotive force of the CPEM-EC waves. The NLSE and the driven DSA and DCA equations are then used to investigate the modulational instability. The relevance of our investigation to laser-plasma interaction experiments and the cores of white dwarf stars is pointed out.
The Schrödinger representation and its relation to the holomorphic representation in linear and affine field theory
Authors: Oeckl Robert
Published: July 2012

We establish a precise isomorphism between the Schrödinger representation and the holomorphic representation in linear and affine field theory. In the linear case, this isomorphism is induced by a one-to-one correspondence between complex structures and Schrödinger vacua. In the affine case we obtain similar results, with the role of the vacuum now taken by a whole family of coherent states. In order to establish these results we exhibit a rigorous construction of the Schrödinger representation and use a suitable generalization of the Segal-Bargmann transform. Our construction is based on geometric quantization and applies to any real polarization and its pairing with any Kähler polarization.
A GW+Bethe-Salpeter calculation on photoabsorption spectra of (CdSe)3 and (CdSe)6 clusters
Authors: Noguchi Yoshifumi , Sugino Osamu , Nagaoka Momoko , Ishii Soh , Ohno Kaoru
Published: July 2012

Photoabsorption spectra are calculated for the magic number clusters, (CdSe)3 and (CdSe)6, using an all-electron mixed basis GW scheme with the excitonic effect incorporated by solving the Bethe-Salpeter equation (BSE). The GW+BSE calculation provided clear size dependence of the optical gap as expected, while magnitude of the gap is overestimated compared to available experimental one. The gap is found very similarly overestimated when using the local density approximation (LDA) within the density functional theory because accidental error cancellation occurs between the significantly underestimated LDA gap and the excitonic effect neglected therein. The excitonic states are described by superposition of many one-particle states that would not be properly described within a one-particle theory, as clearly visualized in the plot of the exciton wavefunctions.
Dual transmission grating based imaging radiometer for tokamak edge and divertor plasmas
Authors: Kumar Deepak , Clayton Daniel J. , Parman Matthew , Stutman Dan , Tritz Kevin , Finkenthal Michael
Published: July 2012

The designs of single transmission grating based extreme ultraviolet (XUV) and vacuum ultraviolet (VUV) imaging spectrometers can be adapted to build an imaging radiometer for simultaneous measurement of both spectral ranges. This paper describes the design of such an imaging radiometer with dual transmission gratings. The radiometer will have an XUV coverage of 20−200 Å with a ∼10 Å resolution and a VUV coverage of 200−2000 Å with a ∼50 Å resolution. The radiometer is designed to have a spatial view of 16°, with a 0.33° resolution and a time resolution of ∼10 ms. The applications for such a radiometer include spatially resolved impurity monitoring and electron temperature measurements in the tokamak edge and the divertor. As a proof of principle, the single grating instruments were used to diagnose a low temperature reflex discharge and the relevant data is also included in this paper.
Phase conversion from graphite toward a simple monoclinic sp3-carbon allotrope
Authors: Wang Jian-Tao , Chen Changfeng , Kawazoe Yoshiyuki
Published: July 2012

We identify by ab initio calculations a simple monoclinic carbon in P2/m (\documentclass[12pt]{minimal}\begin{document}$C_{2h}^{1}$\end{document}C2h1) symmetry with an alternating zigzag and armchair buckling of the carbon sheets in AA stacking, which is formed via a distinct one-layer by one-layer conversion mechanism along the [210] direction assisted by a large lattice distortion. It is dynamically stable and energetically favorable as well as recently identified orthorhombic W- and monoclinic M-carbon. Moreover, this new phase has a wider band gap than diamond's, and is compatible with the experimental x-ray diffraction data. These results broaden our understanding of the direct graphite-to-diamond phase transition.
Small-world topology of functional connectivity in randomly connected dynamical systems
Authors: Hlinka J. , Hartman D. , Paluš M.
Published: July 2012

Characterization of real-world complex systems increasingly involves the study of their topological structure using graph theory. Among global network properties, small-world property, consisting in existence of relatively short paths together with high clustering of the network, is one of the most discussed and studied. When dealing with coupled dynamical systems, links among units of the system are commonly quantified by a measure of pairwise statistical dependence of observed time series (functional connectivity). We argue that the functional connectivity approach leads to upwardly biased estimates of small-world characteristics (with respect to commonly used random graph models) due to partial transitivity of the accepted functional connectivity measures such as the correlation coefficient. In particular, this may lead to observation of small-world characteristics in connectivity graphs estimated from generic randomly connected dynamical systems. The ubiquity and robustness of the phenomenon are documented by an extensive parameter study of its manifestation in a multivariate linear autoregressive process, with discussion of the potential relevance for nonlinear processes and measures.
Liquid flow retardation in nanospaces due to electroviscosity: Electrical double layer overlap, hydrodynamic slippage, and ambient atmospheric CO2 dissolution
Authors: Chang Chih-Chang , Yang Ruey-Jen , Wang Moran , Miau Jiun-Jih , Lebiga Vadim
Published: July 2012

A theoretical investigation is performed into the electroviscous-induced retardation of liquid flows through finitely long nanochannels or nanotubes with large wells at either end. Given the assumption of equilibrium conditions between the ionic solution in the wells and that within the nanochannel or nanotube, an exact solution is derived for the overlapped electrical double layer (EDL) for the case where the concentrations of the positive and negative ions in the wells may be unequal. The ion concentrations in the wells are determined by the conditions of global electroneutrality and mass conservation. It is shown that the overlapped EDL model proposed by Baldessari and Santiago [J. Colloid Interface Sci. 325, 526 (2008)10.1016/j.jcis.2008.06.007] is in fact the same as the “thick EDL model” (i.e., the traditional Poisson-Boltzmann model) when the positive and negative ion concentrations in the large enough wells are both equal to the bulk concentration of the salt solution. Utilizing the proposed overlapped EDL analytical model, an investigation is performed to evaluate the effects of hydrodynamic slippage on the flow retardation caused by electroviscosity in nanochannels or nanotubes. Furthermore, exact and approximate solutions are derived for the electroviscosity in ion-selective nanochannels and nanotubes. It is shown that in the absence of slip, the maximum electroviscosity in nanochannels and nanotubes containing a unipolar solution of simple monovalent counter-ions occurs at surface charge densities of h|σ| = 0.32 nm × C/m2 and a|σ| ≈ 0.4 nm × C/m2, respectively. In addition, it is shown that the electroviscosity in a nanotube is smaller than that in a nanochannel. For example, given a LiCl solution, the maximum electroviscosites in a non-slip nanochannel and non-slip nanotube are ηa/η ≈ 1.6 and 1.47, respectively. For both nanospaces, the electroviscosity is greatly increased when the liquid slip effect is taken into account. Significantly, under slip conditions, the electroviscosity in the nanotube is greater than that in the nanochannel. Finally, an investigation is performed into the effects of ambient atmospheric CO2 dissolution on the electroviscosities of salt/buffer solution and deionized (DI) water in silica nanochannels. The results show that the electroviscosity of CO2-saturated DI water (pH = 5.6) can be reasonably neglected in silica nanochannels with a height of less than 100 nm.
Density profile measurements with X-mode lower cut-off reflectometry in ASDEX Upgrade
Authors: Varela P. , Manso M. ,   ASDEX Upgrade Team
Published: July 2012

Despite the fact that density profile measurements using X-mode lower cut-off reflectometry are foreseen to be used on ITER, little or no experience is available within the reflectometry community and to our knowledge no results on this subject have been published so far. In ASDEX Upgrade the multichannel broadband reflectometer is equipped with both O- and X-mode channels. While X-mode operation was designed for upper cut-off reflection, it is observed that for both high magnetic field and high density discharges the lower cut-off becomes accessible. Here we present reflectometry measurements obtained in ASDEX Upgrade using X-mode lower cut-off and compare both the resulting group delay and density profile with O-mode measurements performed simultaneously over the same plasma region. The possible use of this comparison to provide estimates of the magnetic field is briefly discussed.
Magnetophoretic trajectory tracking magnetometry: A new technique for assessing magnetic properties of submagnetic microparticles and cells
Authors: Kashevsky B. E. , Zholud A. M. , Kashevsky S. B.
Published: July 2012

We develop a new approach for assessing magnetic properties of submagnetic microparticles and cells, magnetophoretic trajectory tracking magnetometry (MTTM), that employs recording of long 2D trajectories of particle motion in a slot fluid channel caused by the action of crossed gravitational and magnetic forces. The studies are focused on the development of theoretical backgrounds of the method and evaluation of its uncertainty caused by the mutual hydrodynamic entrainment of moving particles. Computerized equipment implementing MTTM technique is described and its performance is illustrated. According to our studies, the new technique can serve a reliable experimental method with analytical qualities.
High mass resolution time of flight mass spectrometer for measuring products in heterogeneous catalysis in highly sensitive microreactors
Authors: Andersen T. , Jensen R. , Christensen M. K. , Pedersen T. , Hansen O. , Chorkendorff I.
Published: July 2012

We demonstrate a combined microreactor and time of flight system for testing and characterization of heterogeneous catalysts with high resolution mass spectrometry and high sensitivity. Catalyst testing is performed in silicon-based microreactors which have high sensitivity and fast thermal response. Gas analysis is performed with a time of flight mass spectrometer with a modified nude Bayard-Alpert ionization gauge as gas ionization source. The mass resolution of the time of flight mass spectrometer using the ion gauge as ionization source is estimated to m/Δm > 2500. The system design is superior to conventional batch and flow reactors with accompanying product detection by quadrupole mass spectrometry or gas chromatography not only due to the high sensitivity, fast temperature response, high mass resolution, and fast acquisition time of mass spectra but it also allows wide mass range (0–5000 amu in the current configuration). As a demonstration of the system performance we present data from ammonia oxidation on a Pt thin film showing resolved spectra of OH and NH3.
Design and construction of a guarded hot plate apparatus operating down to liquid nitrogen temperature
Authors: Li Manfeng , Zhang Hua , Ju Yonglin
Published: July 2012

A double-sided guarded hot plate apparatus (GHP) is specifically designed, fabricated, and constructed for the measurement of thermal conductivities of insulation specimens operated down to liquid nitrogen temperature (−196 °C), at different controlled pressures from 0.005 Pa to 0.105 MPa. The specimens placed in this apparatus are 300 mm in diameter at various thicknesses ranging from 4 mm to 40 mm. The apparatus is different from traditional GHP in terms of structure, supporting and heating method. The details of the design and construction of the hot plate, the cold plates, the suspensions, the clampings, and the vacuum chamber of the system are presented. The measurement methods of the temperatures, the input power, the meter area, and the thickness of the specimens are given. The apparatus is calibrated with teflon plates as sample and the maximum deviation from the published data is about 6% for thermal conductivity. The uncertainties for the measurement are also discussed in this paper.
Design and capabilities of an experimental setup based on magnetron sputtering for formation and deposition of size-selected metal clusters on ultra-clean surfaces
Authors: Hartmann H. , Popok V. N. , Barke I. , von Oeynhausen V. , Meiwes-Broer K.-H.
Published: July 2012

The design and performance of an experimental setup utilizing a magnetron sputtering source for production of beams of ionized size-selected clusters for deposition in ultra-high vacuum is described. For the case of copper cluster formation the influence of different source parameters is studied and analyzed. Size-selected clusters are deposited on substrates and the efficiency of an electrostatic quadrupole mass selector is tested. Height analysis using atomic force microscopy (AFM) demonstrates relative standard size deviations of 7%–10% for the particles of various sizes between 6 nm and 19 nm. Combined analysis by AFM and transmission electron microscopy reveals that the clusters preserve almost spherical shape after the deposition on amorphous carbon substrates. Supported nanoparticles of a few nanometres in diameter have crystalline structure with a face-centered cubic (fcc) lattice.
Effects of strongly selective additives on volume phase transition in gels
Authors: Uematsu Yuki , Araki Takeaki
Published: July 2012

We investigate volume phase transition in gels immersed in mixture solvents, on the basis of a three-component Flory-Rehner theory. When the selectivity of the minority solvent component to the polymer network is strong, the gel tends to shrink with an increasing concentration of the additive, regardless of whether it is good or poor. This behavior originates from the difference of the additive concentration between inside and outside the gel. We also found the gap of the gel volume at the transition point can be controlled by adding the strongly selective solutes. By dissolving a strongly poor additive, for instance, the discontinuous volume phase transition can be extinguished. Furthermore, we observed that another volume phase transition occurs far from the original transition point. These behaviors can be well explained by a simplified theory neglecting the nonlinearity of the additive concentration.
Characterization of single crystal chemical vapor deposition diamond detectors for neutron spectrometry
Authors: Gagnon-Moisan F. , Zimbal A. , Nolte R. , Reginatto M. , Schuhmacher H.
Published: July 2012

Detectors made from artificial chemical vapor deposition single crystal diamond have shown great potential for fast neutron spectrometry. In this paper, we present the results of measurements made at the Physikalisch-Technische Bundesanstalt accelerator using neutron fields in the energy range from 7 MeV to 16 MeV. This study presents the first results of the characterization of the detector in this energy range.
Macroscopic and microscopic defects and nonlinear optical properties of KH2PO4 crystals with embedded TiO2 nanoparticles
Authors: Grachev Valentin G. , Vrable Ian A. , Malovichko Galina I. , Pritula Igor M. , Bezkrovnaya Olga N. , Kosinova Anna V. , Yatsyna Vasyl O. , Gayvoronsky Vladimir Ya.
Published: July 2012

Results from the successful growth of high quality KH2PO4 (KDP) crystals with incorporated TiO2 anatase nanoparticles and the characterization of these crystals using several complementary methods are presented. The study allowed the nature and distribution of macroscopic and microscopic defects in the KDP:TiO2 crystals to be clarified. The relationship between these defects and the distribution of TiO2 nanoparticles, and the influence of incorporated nanoparticles on the nonlinear optical properties of composite crystals in comparison with pure crystals were also elucidated. Visual observations, transmission and scanning electron microscopy have shown that the anatase nanoparticles were captured mainly by the pyramidal growth sector and, to a considerably lesser extent, by the prismatic growth sector. Energy dispersive x-ray analysis was able to confirm that the growth layer stacks contain the TiO2 particles. Fourier transformation infrared spectra have clearly shown the presence of an absorption band at about 800 cm−1 in both KDP:TiO2 and TiO2, and the disappearance of the band, associated with hydroxyl OH− groups on the TiO2 surface in KDP:TiO2. Significant variation in the imaginary and real parts of the cubic nonlinear optical susceptibilities and refractive index changes at continuous wave excitation were found in prism and pyramid parts of pure KDP and KDP:TiO2 samples. Deciphering complicated electron paramagnetic resonance spectra in KDP:TiO2 and comparison with published data permitted the identification of paramagnetic defects along with their associated g-factors and zero-field splitting parameters (in some cases for the first time). It was found that the dominant lines belong to four different centers FeA3+, FeB3+, CrR3+, and CrGB3+. From analysis of line intensities it was concluded that the concentration of intrinsic defects like potassium and hydrogen vacancies in KDP:TiO2 is comparatively small, that the concentration of non-controlled impurities in nominally pure KDP samples is several times larger than in KDP:TiO2, and that the concentration of non-controlled impurities in the prismatic part of the KDP:TiO2 boule is approximately twice as large as in the pyramid part.
Application of Landau-Lifshitz-Bloch dynamics to grain switching in heat-assisted magnetic recording
Authors: McDaniel Terry W.
Published: July 2012

Magnetization dynamics in heat-assisted magnetic recording (HAMR) involves magnetization collapse and re-formation under rapid local temperature excursion in a temporally varying applied magnetic field, with temperature likely moving above and below the medium Curie point on nanosecond timescales. Traditional micromagnetic simulation of the writing process in magnetic data storage has been restricted to isothermal processes in which macrospin magnetization dynamics are handled with the well-established Landau-Lifshitz-Gilbert (LLG) algorithm or close variants. Classical LLG treats the magnitude of material magnetization M as fixed (at zero Kelvin), so initial attempts at micromagnetic analysis of HAMR have typically dealt with the effects of temperature variation in HAMR in a somewhat ad hoc manner (e.g., insertion of M(T), A(T), K(T)), and have not been rigorous. A much improved treatment of this problem substitutes the Landau-Lifshitz-Bloch (LLB) algorithm in which thermally driven magnetization variation is treated more correctly in an extended semi-classical Landau-Lifshitz framework Here we study single-grain switching with this method under application of time-varying temperature and H-field. For a typical system setup, we map phase diagrams of grain switching probability over the space of important HAMR parameters such as peak temperature elevation, applied H-field strength, and the synchronization of temperature and field.
Effects of residual surface stress and surface elasticity on the nonlinear free vibration of nanoscale plates
Authors: Wang K. F. , Wang B. L.
Published: July 2012

This paper studies the influence of surface effects (including the residual surface stress and surface elasticity) on the nonlinear free vibrations of nanoscale plates. The motion equations are derived by using the Hamilton’s principle and solved numerically. It is found that the influence of surface effects on the normalized period of nanoscale plates becomes increasingly significant when the thickness of the plate decreases. More importantly, the influence of the surface effects on the normalized vibration period reduces if the initial amplitude of the vibration increases. This tendency is more pronounced for the Mindlin plate theory, which includes the transverse shear effect of the plates. In addition, it is found that both the positive residual surface stress and surface elasticity increase the magnitude of the vibration velocity.
Charge transport in polycrystalline silicon thin-films on glass substrates
Authors: Scheller L.-P. , Nickel N. H.
Published: July 2012

Charge carrier transport in solid-phase crystallized polycrystalline silicon (poly-Si) was investigated as a function of the deposition temperature, Td, the amorphous starting material and the used substrates. The samples were characterized using temperature dependent transport measurements to determine the carrier concentration, mobility, and conductivity. Samples prepared on a-SiN:H covered borofloat glass exhibit a low carrier concentration that is independent of Td. In these samples, charge transport is dominated by intra-grain scattering mechanisms. In contrast, when poly-Si is prepared on corning glass, the carrier concentration shows an inverted U-shape behavior with increasing deposition temperature. The Hall mobility is thermally activated, which is consistent with thermionic carrier emission over potential energy barriers. The change of the activation energy with experimental parameters is accompanied by a large change of the exponential prefactor by more than 4 orders of magnitude. This is indicative of a Meyer-Neldel behavior. Moreover, at low temperatures, the conductivity deviates from an activated behavior indicating hopping transport with a mean hopping distance of ≈140 Å and an energy difference of ≈82 meV between the participating states. To derive insight into the underlying transport mechanisms and to determine information on barrier energy heights and grain-boundary defect-densities, the experimental data were analyzed employing transport models for polycrystalline materials.
Effect of high-energy neutral particles on extreme ultraviolet spectroscopy in large helical device
Authors: Dong Chunfeng , Morita Shigeru , Tokitani Masayuki , Goto Motoshi , Sakaue Hiroyuki , Wang Erhui , Zushi Hideki
Published: July 2012

Spectra measured by an extreme ultraviolet (EUV) spectrometer frequently suffer large spike noise when Large Helical Device is operated in low-density range (≤3 × 1013 cm−3) with neutral beam injection (NBI). The spike noise completely disappears in electron cyclotron heating discharges. In order to examine the effect of NBI, a carbon filter with thickness of 150 nm was installed in the EUV spectrometer. As a result, the spike noise was reduced by an order of magnitude. It is experimentally verified that the spike noise is caused by escaping high-energy neutral particles resulting from the circulating high-energy hydrogen ions borne from NBI.
Cryogenic single-shot spectroscopy of a floating poly-silicon gate transistor
Authors: Tenorio-Pearl J. O. , Milne W. I. , Hasko D. G.
Published: July 2012

Trapped electrons, located close to the channel of a transistor, are promising as data storage elements in non-classical information processing. Cryogenic microwave spectroscopy has shown that these electrons give rise to high quality factor resonances in the drain current and a post excitation dynamic behaviour that is related to the system lifetime. Using a floating poly-silicon gate transistor, single shot spectroscopy is performed to characterise the dynamic behaviour during excitation. This behaviour is seen to be dominated by the decay of the transient component, which gives rise to oscillations around the high quality factor resonance.
The effects of doping and shell thickness on the optical and magnetic properties of Mn/Cu/Fe-doped and Co-doped ZnS nanowires/ZnO quantum dots/SiO2 heterostructures
Authors: Cao Jian , Yang Jinghai , Yang Lili , Wei Maobin , Feng Bo , Han Donglai , Fan Lin , Wang Bingji , Fu Hao
Published: July 2012

In this paper, we demonstrated the encapsulation of Mn/Cu/Fe-doped and co-doped ZnS nanowires (NWs) and ZnO quantum dots (QDs) with a layer of mesoporous SiO2 shell for the purpose of integrating dual emission and ferromagnetism property into one common nanostructure at room temperature. Within the ZnS:Mn2+Cu2+Fe2+/ZnO@SiO2 nanocomposites, ZnS:Mn2+Cu2+Fe2+ NWs and ZnO QDs provided color-tunable visible emission and UV emission, respectively. The color-tunable visible emission in the ZnS:Mn2+Cu2+Fe2+ NWs can be obtained by adjusting the concentrations of Mn2+, Cu2+, and Fe2+ ions. The ferromagnetism of the ZnS:Mn2+Cu2+Fe2+ NWs was observed around room temperature, the mechanism of which was explained by the super-exchange mechanism. The results of the effect of the ZnO QDs shell thickness on the optical properties of the ZnS:Mn2+/ZnO@SiO2 nanocomposites showed that the luminescence intensity of the yellow-orange emission and UV emission reached the highest value when the ratio of ZnS:Mn2+/ZnO equaled 1:5.
Growth and characterizations of semipolar (112¯2) InN
Authors: Dinh Duc V. , Skuridina D. , Solopow S. , Frentrup M. , Pristovsek M. , Vogt P. , Kneissl M. , Ivaldi F. , Kret S. , Szczepańska A.
Published: July 2012

We report on metal-organic vapor phase epitaxial growth of (112¯2) InN on (112¯2) GaN templates on m-plane (101¯0) sapphire substrates. The in-plane relationship of the (112¯2) InN samples is [1¯1¯23]InN||[0001]sapphire and [11¯00]InN||[12¯10]sapphire, replicating the in-plane relationship of the (112¯2) GaN templates. The surface of the (112¯2) InN samples and the (112¯2) GaN templates shows an undulation along [11¯00]InN,GaN, which is attributed to anisotropic diffusion of indium/gallium atoms on the (112¯2) surfaces. The growth rate of the (112¯2) InN layers was 3-4 times lower compared to c-plane (0001) InN. High resolution transmission electron microscopy showed a relaxed interface between the (112¯2) InN layers and the (112¯2) GaN templates, consistent with x-ray diffraction results. Basal plane stacking faults were found in the (112¯2) GaN templates but they were terminated at the InN/(112¯2) GaN interface due to the presence of misfit dislocations along the entire InN/GaN interface. The misfit dislocations were contributed to the fully relaxation and the tilts of the (112¯2) InN layers. X-ray photoelectron spectroscopy was used to determine the polarity of the grown (112¯2) InN sample, indicating an In-polar (112¯2) InN. The valence band maximum was determined to be at (1.7 ± 0.1) eV for the (112¯2) InN sample, comparable to In-polar c-plane InN.
Demonstration of a low electromagnetic pulse laser-driven argon gas jet x-ray source
Authors: Kugland N. L. , Aurand B. , Brown C. G. , Constantin C. G. , Everson E. T. , Glenzer S. H. , Schaeffer D. B. , Tauschwitz A. , Niemann C.
Published: July 2012

Laser-produced plasmas are often used as bright x-ray backlighters for time-resolved plasma diagnostics, but such backlighters simultaneously generate damaging electromagnetic pulse (EMP). A laser-driven Ar gas jet x-ray source has been measured with magnetic flux B-dot probes to produce 20 times ±37% less integrated EMP in the 0.5–2.5 GHz band than a solid chlorinated plastic foil, while retaining 85% of the laser to ≈3 keV x-ray conversion efficiency. These results are important for future backlighter development, since tailoring target density may provide a way to reduce EMP even as laser power increases.
Controlled growth of epitaxial BiFeO3 films using self-assembled BiFeO3-CoFe2O4 multiferroic heterostructures as a template
Authors: Li Yanxi , Yang Yaodong , Yao Jianjun , Viswan Ravindranath , Wang Zhiguang , Li Jiefang , Viehland D.
Published: July 2012

The growth mechanism of a BiFeO3 layer deposited on self assembled (0.65) BiFeO3-(0.35) CoFe2O4 (BFO-CFO) composite thin films was studied. Epitaxial and self-assembled BFO-CFO thin films were deposited on SrTiO3 (111) substrates by pulsed laser deposition and were subsequently used as a seed layer for the deposition of an additional BFO layer. x-ray line scans showed the heterostructures were highly epitaxial. Cross-sectional scanning electron microscopy and focused ion beam images revealed the top BFO layer grew preferentially from BFO nanopillars in the BFO-CFO thin films, thus, demonstrating controlled growth. The multiferroic properties of this new nanostructure were then studied.
Tunneling electroresistance effect in Pt/MgO/Pt/PbTiO3/Pt ferroelectric tunnel junctions
Authors: Ma Zhijun , Zhang Tianjin , Pan Ruikun , Liang Kun , Wang Duofa , Wang Jingang , Wang Jinzhao , Jiang Juan , Qi Yajun , Chu Huifang
Published: July 2012

Tunneling electroresistance (TER) effect was investigated in Pt/MgO/Pt/PbTiO3/Pt ferroelectric tunnel junctions (FTJs) theoretically. Compared to Pt/MgO/PbTiO3/Pt FTJs with the same composite barrier thickness (unit cells), FTJs with a thicker Pt interlayer (2 ∼ 3 unit cells) could provide 1 ∼ 6 orders of magnitude improvement in the TER ratio in a wide range of polarization. Resonant tunneling effect and/or enhanced asymmetry of the potential energy profile induced by the resonant-tunneling structure of MgO/Pt/PbTiO3 in Pt/MgO/Pt/PbTiO3/Pt FTJs is responsible for the TER improvement.
Optimization of electroluminescence from n-ZnO/AlN/p-GaN light-emitting diodes by tailoring Ag localized surface plasmon
Authors: Zhang S. G. , Zhang X. W. , Yin Z. G. , Wang J. X. , Si F. T. , Gao H. L. , Dong J. J. , Liu X.
Published: July 2012

The localized surface plasmon (LSP)-enhanced n-ZnO/AlN/p-GaN light-emitting diodes (LEDs) were fabricated by inserting Ag nanoparticles (NPs) into the ZnO/AlN interface. To investigate the effects of morphology of Ag NPs on the electroluminescence (EL) of device, the Ag NPs with various sizes were prepared by annealing Ag thin films with different deposition times. It is found that the insertion of Ag NPs with suitable size and surface coverage is favorable for the effective resonant coupling between excitons in ZnO and LSP of Ag NPs, and thereby significantly improve the EL performance of the device. For the n-ZnO/AlN/p-GaN LED with 10 nm Ag NPs, a maximum EL enhancement factor of 3.7 was observed at 420 nm at an injection current of 10 mA. For the device with the smaller Ag NPs, only the weaker enhancement is observed due to the smaller scattering cross section. On the other hand, in the case of the larger Ag NPs, the energy mismatch between the LSP of Ag NPs and the near band-edge emission of ZnO, as well as the poor crystalline quality of the ZnO film, leads to degradation in device performance.
Significant deterioration of energy products in exchange-coupled composite magnets
Authors: Xia J. , Zhao G. P. , Zhang H. W. , Cheng Z. H. , Feng Y. P. , Ding J. , Yang H. T.
Published: July 2012

Hysteresis loops and energy products have been calculated reliably for a hard/soft/hard trilayer system with a deviation of easy axis β taken into account, which affects the coercivity significantly, and hence leads to much smaller energy products than those predicted by the previous theory. Such a deterioration is much sharper than the corresponding fall for a single-phased material and a 30° deviation of in-plane easy axis could result in a drop of the maximum energy product by more than 60%. Consequently, the advantage of the composite phase can be realized only when the material is well oriented, which offers a possible explanation to the large discrepancy between the experimental and theoretical energy products.