bluuebunny/crossref_metadata_2025 huggingface dataset:
Trapping-charging ability and electrical properties study of amorphous insulator by dielectric spectroscopy
Authors: Mekni Omar , Arifa Hakim , Askri Besma , Raouadi Khaled , Damamme Gilles , Yangui Béchir
Published: September 2014

Usually, the trapping phenomenon in insulating materials is studied by injecting charges using a Scanning Electron Microscope. In this work, we use the dielectric spectroscopy technique for showing a correlation between the dielectric properties and the trapping-charging ability of insulating materials. The evolution of the complex permittivity (real and imaginary parts) as a function of frequency and temperature reveals different types of relaxation according to the trapping ability of the material. We found that the space charge relaxation at low frequencies affects the real part of the complex permittivity ε′ and the dissipation factor Tan(δ). We prove that the evolution of the imaginary part of the complex permittivity against temperature ε″=f(T) reflects the phenomenon of charge trapping and detrapping as well as trapped charge evolution Qp(T). We also use the electric modulus formalism to better identify the space charge relaxation. The investigation of trapping or conductive nature of insulating materials was mainly made by studying the activation energy and conductivity. The conduction and trapping parameters are determined using the Correlated Barrier Hopping (CBH) model in order to confirm the relation between electrical properties and charge trapping ability.
Communication: Low-temperature approximation of the virial series for the Lennard-Jones and modified Lennard-Jones models
Authors: Ushcats M. V.
Published: September 2014

The regularity of the existing data on the virial coefficients for the Lennard-Jones and modified Lennard-Jones models has allowed a rough extrapolation to the coefficients of higher orders. The corresponding approximation of the infinite virial series has been proposed for the limited temperature interval: 0.4–0.8 of the critical temperature. The loci of zero points of isothermal bulk modulus obtained on the basis of this approximation are close to the vapor-liquid branch of the experimental binodal rather than spinodal. In addition, those points ((dP/dV)T = 0) almost coincide with the divergence points of the approximated virial series that may eliminate some disputable questions about the boundaries of adequacy for the virial equation of state and makes the theoretical isotherms qualitatively similar to the real in the condensation region.
Fourier plane imaging microscopy
Authors: Dominguez Daniel , Alharbi Nouf , Alhusain Mdhaoui , Bernussi Ayrton A. , Peralta Luis Grave de
Published: September 2014

We show how the image of an unresolved photonic crystal can be reconstructed using a single Fourier plane (FP) image obtained with a second camera that was added to a traditional compound microscope. We discuss how Fourier plane imaging microscopy is an application of a remarkable property of the obtained FP images: they contain more information about the photonic crystals than the images recorded by the camera commonly placed at the real plane of the microscope. We argue that the experimental results support the hypothesis that surface waves, contributing to enhanced resolution abilities, were optically excited in the studied photonic crystals.
Determination of magnetic vortex chirality by local field excited gyration
Authors: Xie Kaixuan , Lin Weiwei , Zhang Peng , Sang Hai
Published: September 2014

We show the chirality dependent dynamics of the single magnetic vortex in a submicron permalloy rectangle due to the symmetry breaking by a local magnetic field. For the clockwise (counter-clockwise) chirality, the local positive (negative) field leads to the softening of the gyrotropic mode of vortex core relative to the case of the homogeneous field, resulting in an asymmetric dependence of the gyrotropic frequency which depends on the vortex chirality. The gyrotropic frequency has strong correlation with the distance from the vortex core equilibrium position to the edge of the rectangle. We enlighten that the measurement of the gyrotropic frequency of single vortex under the local field can be an alternative way to determine the vortex chirality at room temperature.
Importance of growth temperature on achieving lattice-matched and strained InAlN/GaN heterostructure by plasma-assisted molecular beam epitaxy
Authors: Jeganathan K. , Shimizu M.
Published: September 2014

We investigate the role of growth temperature on the optimization of lattice-matched In0.17Al0.83N/GaN heterostructure and its structural evolutions along with electrical transport studies. The indium content gradually reduces with the increase of growth temperature and approaches lattice-matched with GaN having very smooth and high structural quality at 450ºC. The InAlN layers grown at high growth temperature (480ºC) retain very low Indium content of ∼ 4 % in which cracks are mushroomed due to tensile strain while above lattice matched (>17%) layers maintain crack-free compressive strain nature. The near lattice-matched heterostructure demonstrate a strong carrier confinement with very high two-dimensional sheet carrier density of ∼2.9 × 1013 cm−2 with the sheet resistance of ∼450 Ω/□ at room temperature as due to the manifestation of spontaneous polarization charge differences between InAlN and GaN layers.
Spatio-temporal coherence of free-electron laser radiation in the extreme ultraviolet determined by a Michelson interferometer
Authors: Hilbert V. , Rödel C. , Brenner G. , Döppner T. , Düsterer S. , Dziarzhytski S. , Fletcher L. , Förster E. , Glenzer S. H. , Harmand M. , Hartley N. J. , Kazak L. , Komar D. , Laarmann T. , Lee H. J. , Ma T. , Nakatsutsumi M. , Przystawik A. , Redlin H. , Skruszewicz S. , Sperling P. , Tiggesbäumker J. , Toleikis S. , Zastrau U.
Published: September 2014

A key feature of extreme ultraviolet (XUV) radiation from free-electron lasers (FELs) is its spatial and temporal coherence. We measured the spatio-temporal coherence properties of monochromatized FEL pulses at 13.5 nm using a Michelson interferometer. A temporal coherence time of (59±8) fs has been determined, which is in good agreement with the spectral bandwidth given by the monochromator. Moreover, the spatial coherence in vertical direction amounts to about 15% of the beam diameter and about 12% in horizontal direction. The feasibility of measuring spatio-temporal coherence properties of XUV FEL radiation using interferometric techniques advances machine operation and experimental studies significantly.
Phonon drag effect on Seebeck coefficient of ultrathin P-doped Si-on-insulator layers
Authors: Salleh F. , Oda T. , Suzuki Y. , Kamakura Y. , Ikeda H.
Published: September 2014

The contribution of the phonon drag effect to the Seebeck coefficient of P-doped ultrathin Si-on-insulator (SOI) layers with a thickness of 9–100 nm is investigated for near-room-temperature applications. The contribution is found to be significant in the lightly doped region and to depend on the carrier concentration with increasing carrier concentration above ∼5 × 1018 cm−3. Moreover, the contribution is not influenced by SOI thickness above 9 nm. On the basis of phonon mean-free-path calculations considering phonon scattering processes, the phonon drag part of the SOI Seebeck coefficient in the lightly doped region is mainly governed by phonon-phonon scattering. Furthermore, in higher concentration regions, the dependence of phonon drag can be qualitatively explained by the interaction between phonons and doped impurities.
Photoluminescence properties and exciton dynamics in monolayer WSe2
Authors: Yan Tengfei , Qiao Xiaofen , Liu Xiaona , Tan Pingheng , Zhang Xinhui
Published: September 2014

In this work, comprehensive temperature and excitation power dependent photoluminescence and time-resolved photoluminescence studies are carried out on monolayer WSe2 to reveal its properties of exciton emissions and related excitonic dynamics. Competitions between the localized and delocalized exciton emissions, as well as the exciton and trion emissions are observed, respectively. These competitions are suggested to be responsible for the abnormal temperature and excitation intensity dependent photoluminescence properties. The radiative lifetimes of both excitons and trions exhibit linear dependence on temperature within the temperature regime below 260 K, providing further evidence for two-dimensional nature of monolayer material.
Copper nanoparticle formation in a reducing gas environment
Authors: ten Brink Gert H. , Krishnan Gopi , Kooi Bart J. , Palasantzas George
Published: September 2014

Although copper nanoparticles are used as model nanomaterial because of their small nucleation barrier, their oxidization sensitivity hampers production of fully metallic nanoparticles with controlled size and shape. Nevertheless, we demonstrate here synthesis of copper nanoparticles, via high pressure magnetron sputtering, having highly tunable sizes and shapes over a size range spanning two orders of magnitude. This is achieved by exploiting a reducing gas environment to mediate proper nucleation conditions, allowing size control of nanoparticles with robust motifs for particle sizes ∼5–300 nm. However, due to rapid coalescence oxidation-free nanoparticles cannot be produced monodisperse for sizes larger than ∼30 nm.
Roles of solvent additive in organic photovoltaic cells through intensity dependence of current-voltage characteristics and charge recombination
Authors: Wang Dong Hwan , Kyaw Aung Ko Ko
Published: September 2014

In this research, the enhanced power conversion efficiency of PBnDT-FTAZ:PC70BM bulk-heterojunction (BHJ) solar cells (over 7%), fabricated with a solvent additive (1,8-diiodooctane, 3%), was demonstrated. The appropriate ratio of solvent additive leads to a device with increased JSC, fill factor, and favorably controlled nanomorphology phase separation. Furthermore, the device with BHJ film fabricated with the solvent additive exhibited improved charge collection and simultaneously reduced charge recombination from a systematic light intensity analysis. The lack of Shockley-Read-Hall recombination at open circuit, the dominance of bimolecular recombination only when approaching open circuit, and an improved charge collection probability (95.5%) at short circuit contribute to high performance organic photovoltaic cells.
Bias-dependence of the tunneling electroresistance and magnetoresistance in multiferroic tunnel junctions
Authors: Useinov Artur , Kalitsov Alan , Velev Julian , Kioussis Nicholas
Published: September 2014

We predict that the tunneling electroresistance effect is present at finite bias even in multiferroic tunnel junctions (MFTJs) with inversion symmetry. The effect is highly sensitive to the relative magnetization orientation in the electrodes. In addition, we demonstrate control of the bias-dependence of the tunneling magnetoresistance (TMR) in MFTJs via switching of the ferroelectric polarization of the barrier. The polarization induces a monotonic bias behavior in TMR which can be reversed by polarization switching. The magnitude of both effects is proportional to the polarization. The underlying mechanism is the inversion symmetry breaking due to the polarization combined with the interplay of the bias-induced and polarization-induced spin-dependent interfacial screening. These results expand the possibilities for the next-generation multifunctional devices.
An optical fiber optofluidic particle aspirator
Authors: Murugan Ganapathy S. , Belal Mohammad , Grivas Christos , Ding Ming , Wilkinson James S. , Brambilla Gilberto
Published: September 2014

A fiberized optofluidic particle trapping device based on a micro-slot fabricated in a standard single-mode optical fiber by femtosecond laser micromachining is demonstrated. While fluidic convective motions move a large number of microparticles into the slot, the optical mode propagating in the nearby optical fiber core is exploited to trap and propel the particles inside the slot, thereby facilitating their collection at one of the slot extremities. The combined effect of fluidic and optical trapping allows for the collection of particles from as far as 60 μm away from the optical trap. Application to particle and live cell trapping and propulsion is demonstrated.
Vertical vibration and shape oscillation of acoustically levitated water drops
Authors: Geng D. L. , Xie W. J. , Yan N. , Wei B.
Published: September 2014

We present the vertical harmonic vibration of levitated water drops within ultrasound field. The restoring force to maintain such a vibration mode is provided by the resultant force of acoustic radiation force and drop gravity. Experiments reveal that the vibration frequency increases with the aspect ratio for drops with the same volume, which agrees with the theoretical prediction for those cases of nearly equiaxed drops. During the vertical vibration, the floating drops undergo the second order shape oscillation. The shape oscillation frequency is determined to be twice the vibration frequency.
Global Potential Energy Surface for the H+CH4↔H2+CH3 Reaction using Neural Networks
Authors: Xu Xin , Chen Jun , Zhang Dong H.
Published: September 2014

A global potential energy surface (PES) for the H+CH4↔H2+CH3 reaction has been constructed using the neural networks method based on 47783 high level ab initio geometry points. Extensive quasi-classical trajectories and quantum scattering calculations were carried out to check the convergence of the PES. This PES, fully converged with respect to the fitting procedure and the number of ab initio points, has a very small fitting error, and is much faster on evaluation than the modified Shepard interpolating PES, representing the best available PES for this benchmark polyatomic system.
Molecular Dynamics Study on Configuration Energy and Radial Distribution Functions of Ammonium Dihydrogen Phosphates Solution
Authors: Wang Kun , Zhao Ya-fan , Lu Gui-wu , Wang Yu-liang , Chen Ju-na , Su De-zhi
Published: September 2014

Molecular dynamics simulations were carried out to study the configuration energy and radial distribution functions of mmonium dihydrogen phosphate solution at different temperatures. The dihydrogen phosphate ion was treated as a seven-site model and the ammonium ion was regarded as a five-site model, while a simple-point-charge model for water molecule. An unusually local particle number density fluctuation was observed in the system at saturation temperature. It can be found that the potential energy increases slowly with the temperature from 373 K to 404 K, which indicates that the ammonium dihydrogen phosphate has partly decomposed. The radial distribution function between the hydrogen atom of ammonium cation and the oxygen atom of dihydrogen phosphate ion at three different temperatures shows obvious difference, which indicates that the average H-bond number changes obviously with the temperature. The temperature has an influence on the combination between hydrogen atoms and phosphorus atoms of dihydrogen phosphate ion and there are much more growth units at saturated solutions.
Uniform B-C-N Ternary Monolayer from Non-Metal Filled g-C3N4 Sheet
Authors: Zhang Na , Wu Xiao-jun
Published: September 2014

By using first principles calculations, four two-dimensional B-C-N ternary sheets with ordered and uniform element distribution are predicted based on the C, B, or N filled g-C3N4 sheet. These B-C-N ternary sheets are metallic except for B4-C3N4 monolayer, which is a semiconductor with an energy band gap of 1.18 eV. In particular, the B3C-C3N4 is a ferromagnetic metal with a net magnetic moment of 0.57 μB/cell, which can be used to develop metal-free spintronic device. The calculated formation energy indicates these B-C-N ternary sheets are highly thermal stable. It presents a new route to obtain uniform B-C-N ternary sheet for electronic and spintronic applications.
Hydrothermal Synthesis and Efficient Visible Light Photocatalytic Properties of InVO4 Hierarchical Microspheres and InVO4 Nanowires
Authors: Lin Xue , Zhao Shi-duo , Guo Xiao-yu , Gao Xin , Shi Jiu-jing , Liu Yi-li , Zhai Hong-ju , Wang Qing-wei
Published: September 2014

In this work, InVO4 hierarchical microspheres and InVO4 nanowires were successfully synthesized by a facile hydrothermal method. Field emission scanning electron microscopy showed that InVO4 crystals can be fabricated in different morphologies by simply manipulating the reaction parameters of hydrothermal process. The as-prepared InVO4 photocatalysts exhibited higher photocatalytic activities in the degradation of rhodamine B under visible-light irradiation (λ>420 nm) compared with commercial P25 TiO2. Furthermore, the as-synthesized InVO4 hierarchical microspheres showed higher photocatalytic activity than that of InVO4 nanowires. Up to 100% Rh B (3 μmol/L) was decolorized after visible-light irradiation for 40 min. In addition, the reason for the difference in the photocatalytic activities for InVO4 hierarchical microspheres and InVO4 nanowires was studied based on their structures and morphologies.
Preparation of TiO2/Bi2O3 Microfibers and Their Photocatalytic Activity
Authors: Ma Zhan-ying , Deng Ling-juan , Li Xiao-bo , Fan Guang
Published: September 2014

A series of TiO2/Bi2O3 heterojunction microfibers have been fabricated using cotton fibers as bio-templates, and characterized by XRD, SEM and UV-Vis techniques. Results reveal that Bi2O3 in the TiO2/Bi2O3 sample is assigned to monoclinic and tetragonal mix-crystal phase. Fibers lengths can reach several micrometers and diameters range from 0.5 μm to 3 μm. Compared with pure TiO2 and Bi2O3, TiO2/Bi2O3 samples display better absorption in visible light region. Photocatalytic activity was evaluated by degradation of MB under visible light irradiation. TiO2/Bi2O3 microfibers exhibite much higher activity than pure TiO2 and Bi2O3, and 22.84%TiO2/Bi2O3 can achieve the decomposition of about 95%MB, which is attributed to synergistic effects of the strong visible-light absorption of TiO2/Bi2O3 microfibers and the heterojunction formed between TiO2 and Bi2O3.
Effect of Molybdenum Doping on Oxygen Permeation Properties and Chemical Stability of SrCo0.8Fe0.2O3-δ
Authors: Song Chun-lin , Fang Shu-min
Published: September 2014

The phase composition, microstructure, thermal expansion coefficients, oxygen permeation properties and chemical stability of SrCo0.7Fe0.2Mo0.1 O3-δ (SCFM) were investigated and compared with those of SrCo0.8Fe0.2O3-δ (SCF). Single phase SCFM was successfully prepared by a combined EDTA-citric method. SCFM shows a lower thermal expansion coefficient (24×10-6-29×10-6/K) than SCF between 500 and 1050 °C, indicating a more stable structure. SCFM shows a high oxygen permeation flux, although the oxygen flux of SCFM decreases slightly because of Mo dopant. Furthermore, it was demonstrated that the doping of Mo in SCF can prevent the order-disorder transition and improves the chemical stability to CO2.
Composite Cathode based on Mn-doped Perovskite Niobate-Titanate for Efficient Steam Electrolysis
Authors: Zhang Jun , Xie Kui , Li Yuan-xin , Qi Wen-tao , Ruan Cong , Wu Yu-cheng
Published: September 2014

Redox-active Mn is introduced into the B site of redox-stable perovskite niobate-titanate to improve the electrocatalytic activity of composite cathode in an oxide-ion-conducting solid oxide electrolyzer. The XRD and XPS results reveal the successful partial replacement of Ti/Nb by Mn in the B site of niobate-titanate. The ionic conductivities of the Mn-doped niobate-titanate are significantly improved by approximately 1 order of magnitude in reducing atmosphere and 0.5 order of magnitude in oxidizing atmosphere compared with bare niobate-titanate at 800 °C. The current efficiency for Mn-doped niobate-titanate cathode is accordingly enhanced by ~25% and 30% in contrast to the bare cathode with and without reducing gas flowing over the cathode under the applied voltage of 2.0 V at 800 °C in an oxide-ion-conducting solid oxide electrolyzer, respectively.
Nanocomposites of Polydiacetylene and Rare Earth Ions with Reversible Thermochromism
Authors: Fu Kai-yu , Chen Dao-yong
Published: September 2014

We report a facile approach to water-dispersible polydiacetylene/rare earth ions nanocomposites with reversible thermochromism. The nanocomposites were prepared by doping rare earth ions Dy3+ or Sm3+ into layer-structured 10,12-pentacosadiynoic acid (PCDA) nanoparticles to obtain PCDA/rare earth ions nanocomposites (PCDA-RE) and subsequently annealing PCDA-RE at the temperature slightly higher than the melting point of pure PCDA crystals, followed by topochemically polymerizing the annealed PCDA-RE. The polymerized PCDA-RE, i.e. poly(10,12-pentacosadiynoic acid)/rare earth ions nanocomposites (PDA-RE: PDA-Dy or PDA-Sm), are largely reversible (PDA-Sm) or even completely reversible (PDA-Dy) in the thermochromism, while, without the doping, pure PDA is completely irreversible. It is confirmed that, PDA-RE are also layer-structured with a d-spacing of 5.4 nm, higher than the d-spacing of pure PDA (4.7 nm). In PDA-RE, the rare earth ions form a layer in-between and interact strongly with the PDA bilayers, being responsible for the high degree or even the complete reversibility. This is the first example to make PDA completely reversible through the doping of rare earth ions; the annealing process is essential for the complete reversibility since it removes any defects in the structure.
Gelled Ionic Liquid/PMMA Polymer Electrolyte Prepared by Radical Polymerization
Authors: Li Li-bo , Yang Shuo , Li Jie-si , Guo Shao-wen
Published: September 2014

The gel polymer electrolyte containing N-propyl, methylpyrrolidinium bis((trifluoromethyl) sulfonyl)imide (PYR13TFSI) with better performance is prepared by radical polymerization method. The interface status between the LiFePO4 electrode and the electrolyte is characterized by a scanning electron microscope and X-ray photoelectron spectroscopy (XPS). There is a layer of membrane on the gel electrolyte and perfect shell membranes on the surface of active LiFePO4 cluster, on the other hand, N and S photoelectron signals are observed in XPS spectra after charge-discharge cycles. The results show that the ionic liquids and unpolymerized methyl methacrylate incorporate into the electrode surface and form the SEI membrane with Li ion and electrons while the gel electrolyte contacts with the electrode. The formation process of the SEI membrane needs at least three cycles, the discharge capacity increases as the SEI membrane becomes sufficiently thick, which blocks further electron transfer, and the system may approach steady state. The performance of cell with ionic liquid gel polymer electrolyte is measured at different rate. The cells retain 132 mAh/g at 0.2 C, 128 mAh/g at 0.5 C, and 120 mAh/g at 1.0 C after 30 cycles with charge-discharge efficiency of ca. 98% at every rate.
Structural, electronic, vibrational and dielectric properties of selected high-shape K semiconductor oxides
Authors: Scolfaro L M R , Alves H W Leite , Borges P D , Garcia J C , da Silva E F
Published: September 2014

The semiconductor oxides SnO2, HfO2, ZrO2, TiO2 and SrTiO3 are interesting materials for applications as high-K dielectric gate materials in silicon-based devices and spintronics, among others. Here we review our theoretical work about the structural, electronic and vibrational properties of these oxides in their most stable structural phases, including dielectric properties as derived from the electronic structure taking into account the lattice contribution. Finally, we address the recent role played by the presence of transition metal atoms in semiconductor oxides, considering in particular SnO2 as an example in forming diluted magnetic alloys.
The role of coercivity and dislocations for films with perpendicular magnetic anisotropy
Authors: Corredor E C , Coffey D , Arnaudas J I , Proietti M G , Ciria M
Published: September 2014

Understanding and controlling macroscopic quantities directly associated with a random field, such as the coercive field H
c and dislocations in magnetic materials, is important for many applications that include films with perpendicular magnetic anisotropy. Here, using a model system with perpendicular magnetic anisotropy, Cu/Ni/Cu, we show that H
c in double 4 nm thick Ni films is about 0.65 times the value obtained for the single Ni film, a fact that can be understood if the propagation of misfit dislocations is not transmitted to the second magnetic block, implying that its statistical distribution remains unchanged whereas the magnetic driving force increases with the nickel thickness. This interpretation is based on the direct measurement of the in-plane and out-of-plane lattice parameters of the Ni blocks by the extended x-ray absorption fine structure method, a chemically selective technique tuned to probe exclusively the environment of the Ni atoms. With this finding and applying the rigid domain walls model, the H
c ratio between double and single Ni films is calculated, yielding a value of 0.71.
Quantitative determination of In clustering in In-rich InxGa1−xN thin films
Authors: Shang Xiaoxia , Luca Marta De , Pettinari Giorgio , Bisognin Gabriele , Amidani Lucia , Fonda Emiliano , Boscherini Federico , Berti Marina , Ciatto Gianluca
Published: September 2014

We investigated atomic ordering in In-rich In
x
Ga1−x
N epilayers in order to obtain an understanding of whether a deviation from a random distribution of In atoms in the group-III sublattice could be the origin of the strong carrier localization and defect-insensitive emission of these semiconductor alloys. This phenomenon can be exploited for application in optoelectronics. By coupling In K-edge x-ray absorption spectroscopy and high resolution x-ray diffraction, we were able to discard the hypothesis of significant phase separation into InN + GaN, in agreement with previous N K-edge absorption spectroscopy. However, we found an enrichment of In neighbours in the second atomic shell of In as compared to random statistics (clustering) for x = 0.82, while this is not the case for x = 0.46. This result, which is also supported by optical spectroscopy, is likely to stimulate new theoretical studies on In
x
Ga1−x
N alloys with a very high In concentration.
Toroidal dipolar responses in a planar metamaterial
Authors: Guo Linyan , Li Minhua , Yang Helin , Huang Xiaojun , Wu Song
Published: September 2014

Both the magnetic toroidal dipolar (MTD) response and electric toroidal dipolar (ETD) response have been achieved and studied in the microwave region by designing a feasible planar metamaterial. By changing the polarized direction of a normally incident wave, two different coupling modes are observed, and therefore MTD and ETD responses can be achieved accordingly. It is also confirmed by scattered powers for various multipole moments and field distributions that they dominate over other traditional multipole responses at 5.69 GHz and 11.69 GHz, respectively. In view of the design feasibility of planar metamaterial, these resonance-enhanced MTD and ETD responses could provide an avenue for various interesting phenomena associated with the elusive toroidal moments.
HV2112, a Thorne–Żytkow object or a super asymptotic giant branch star
Authors: Tout Christopher A. , Żytkow Anna N. , Church Ross P. , Lau Herbert H. B. , Doherty Carolyn L. , Izzard Robert G.
Published: September 2014

The very bright red star HV2112 in the Small Magellanic Cloud could be a massive Thorne–Żytkow object (TŻO), a supergiant-like star with a degenerate neutron core. With a luminosity of over 105 L⊙, it could also be a super asymptotic giant branch (SAGB) star, a star with an oxygen/neon core supported by electron degeneracy and undergoing thermal pulses with third dredge up. Both TŻOs and SAGB stars are expected to be rare. Abundances of heavy elements in HV2112's atmosphere, as observed to date, do not allow us to distinguish between the two possibilities based on the latest models. Molybdenum and rubidium can be enhanced by both the irp-process in a TŻO or by the s-process in SAGB stars. Lithium can be generated by hot bottom burning at the base of the convective envelope in either. HV2112's enhanced calcium could thus be the key determinant. Neither SAGB stars nor TŻOs are known to be able to synthesize their own calcium but it may be possible to produce it in the final stages of the process that forms a TŻO, when the degenerate electron core of a giant star is tidally disrupted by a neutron star. Hence, it is more likely, on a fine balance, that HV2112 is indeed a genuine TŻO.
An ant-associated mesostigmatid mite in Baltic amber
Authors: Dunlop Jason A. , Kontschán Jenő , Walter David E. , Perrichot Vincent
Published: September 2014

Fossil mesostigmatid mites (Acari: Parasitiformes: Mesostigmata) are extremely rare, and specimens from only nine families, including four named species, have been described so far. A new record ofMyrmozerconsp. described here from Eocene (ca44–49 Myr) Baltic amber represents the first—and so far only—fossil example of the derived, extant family Laelapidae. Significantly, modern species of this genus are habitually myrmecophilous and the fossil mite described here is preserved attached to the head of the dolichoderine antCtenobethylus goepperti(Mayr, 1868). It thus offers the oldest unequivocal evidence for an ecological association between mesostigmatid mites and social insects in the order Hymenoptera.
George Bellamy Mackaness. 20 August 1922 — 4 March 2007
Authors: Carter Philip B.
Published: September 2014

George Mackaness was an Australian immunologist, educated in Sydney, London and Oxford, who spent his professional career working in Australia and the USA. He is prominently recognized for his work elucidating the life history of the macrophage, the cell in animals so important in combating infection. Mackaness is credited with coining the term ‘activated macrophage’ to denote the enhanced abilities of a macrophage subset that he defined as particularly significant in controlling intracellular infections, of which tuberculosis (TB) is perhaps the most important. In collaboration with students and colleagues over many years, Mackaness built a body of work that better characterized the cellular immune response as complementary to the previously known humoral, or antibody, response and contributed to an understanding of the intercellular communications necessary in initiating and maintaining an effective immune response. In the end, he brought broad attention to the process by which blood monocytes gain increased destructive attributes as a necessary part of the immune response to intracellular infectious agents. Mackaness began his research career during the dawn of antibiotics and contributed importantly to the development of several novel antibiotics for the treatment of TB, among them isoniazid, which is still used to great effect. Less appreciated were his mid-career contributions to heart disease and his later role in bringing the first new class of therapeutics to clinical practice that changed and greatly improved the prevention and treatment of hypertension, stroke, kidney disease, heart attack and congestive heart failure.
Mechanobiological stability: a new paradigm to understand the enlargement of aneurysms?
Authors: Cyron C. J. , Wilson J. S. , Humphrey J. D.
Published: September 2014

Static and dynamic mechanical instabilities were previously suggested, and then rejected, as mediators of aneurysmal development, which leaves open the question of the underlying mechanism. In this paper, we suggest as a new paradigm the interpretation of aneurysms as mechanobiological instabilities. For illustrative purposes, we compare analytical calculations with computational simulations of the growth and remodelling of idealized fusiform abdominal aortic aneurysms and experimental and clinical findings. We show that the concept of mechanobiological stability is consistent with the impact of risk factors such as age, smoking or diabetes on the initiation and enlargement of these lesions as well as adaptive processes in the healthy abdominal aorta such as dilatation during ageing or in hypertension. In general, high stiffness, an increased capacity for stress-mediated matrix production, and slow matrix turnover all improve the mechanobiological stability of blood vessels. This theoretical understanding may help guide prognosis and the development of future therapies for aneurysms as it enables systematic ways to attenuate enlargement.
Mechanics and energetics in tool manufacture and use: a synthetic approach
Authors: Wang Liyu , Brodbeck Luzius , Iida Fumiya
Published: September 2014

Tool manufacture and use are observed not only in humans but also in other animals such as mammals, birds and insects. Manufactured tools are used for biomechanical functions such as effective control of fluids and small solid objects and extension of reaching. These tools are passive and used with gravity and the animal users' own energy. From the perspective of evolutionary biology, manufactured tools are extended phenotypes of the genes of the animal and exhibit phenotypic plasticity. This incurs energetic cost of manufacture as compared to the case with a fixed tool. This paper studies mechanics and energetics aspects of tool manufacture and use in non-human beings. Firstly, it investigates possible mechanical mechanisms of the use of passive manufactured tools. Secondly, it formulates the energetic cost of manufacture and analyses when phenotypic plasticity benefits an animal tool maker and user. We take a synthetic approach and use a controlled physical model, i.e. a robot arm. The robot is capable of additively manufacturing scoop and gripper structures from thermoplastic adhesives to pick and place fluid and solid objects, mimicking primates and birds manufacturing tools for a similar function. We evaluate the effectiveness of tool use in pick-and-place and explain the mechanism for gripper tools picking up solid objects with a solid-mechanics model. We propose a way to formulate the energetic cost of tool manufacture that includes modes of addition and reshaping, and use it to analyse the case of scoop tools. Experiment results show that with a single motor trajectory, the robot was able to effectively pick and place water, rice grains, a pebble and a plastic box with a scoop tool or gripper tools that were manufactured by itself. They also show that by changing the dimension of scoop tools, the energetic cost of tool manufacture and use could be reduced. The work should also be interesting for engineers to design adaptive machines.
Comparison of an effect-model-law-based method versus traditional clinical practice guidelines for optimal treatment decision-making: application to statin treatment in the French population
Authors: Kahoul Riad , Gueyffier François , Amsallem Emmanuel , Haugh Margaret , Marchant Ivanny , Boissel François-Henri , Boissel Jean-Pierre
Published: September 2014

Healthcare authorities make difficult decisions about how to spend limited budgets for interventions that guarantee the best cost-efficacy ratio. We propose a novel approach for treatment decision-making, OMES—in French: Objectif thérapeutique Modèle Effet Seuil (in English: Therapeutic Objective–Threshold–Effect Model; TOTEM). This approach takes into consideration results from clinical trials, adjusted for the patients' characteristics in treatment decision-making. We compared OMES with the French clinical practice guidelines (CPGs) for the management of dyslipidemia with statin in a computer-generated realistic virtual population, representing the adult French population, in terms of the number of all-cause deaths avoided (number of avoided events: NAEs) under treatment and the individual absolute benefit. The total budget was fixed at the annual amount reimbursed by the French social security for statins. With the CPGs, the NAEs was 292 for an annual cost of 122.54 M€ compared with 443 with OMES. For a fixed NAEs, OMES reduced costs by 50% (60.53 M€ yr
−1
). The results demonstrate that OMES is at least as good as, and even better than, the standard CPGs when applied to the same population. Hence the OMES approach is a practical, useful alternative which will help to overcome the limitations of treatment decision-making based uniquely on CPGs.
Plasticity predicts evolution in a marine alga
Authors: Schaum C. Elisa , Collins Sinéad
Published: September 2014

Under global change, populations have four possible responses: ‘migrate, acclimate, adapt or die’ (Gienappet al. 2008 Climate change and evolution: disentangling environmental and genetic response.Mol. Ecol.17, 167–178. (doi:10.1111/j.1365-294X.2007.03413.x)). The challenge is to predict how much migration, acclimatization or adaptation populations are capable of. We have previously shown that populations from more variable environments are more plastic (Schaumet al. 2013 Variation in plastic responses of a globally distributed picoplankton species to ocean acidification.Nature3, 298–230. (doi:10.1038/nclimate1774)), and here we use experimental evolution with a marine microbe to learn that plastic responses predict the extent of adaptation in the face of elevated partial pressure of CO2(pCO2). Specifically, plastic populations evolve more, and plastic responses in traits other than growth can predict changes in growth in a marine microbe. The relationship between plasticity and evolution is strongest when populations evolve in fluctuating environments, which favour the evolution and maintenance of plasticity. Strikingly, plasticity predicts the extent, but not direction of phenotypic evolution. The plastic response to elevated pCO2in green algae is to increase cell division rates, but the evolutionary response here is to decrease cell division rates over 400 generations until cells are dividing at the same rate their ancestors did in ambient CO2. Slow-growing cells have higher mitochondrial potential and withstand further environmental change better than faster growing cells. Based on this, we hypothesize that slow growth is adaptive under CO2enrichment when associated with the production of higher quality daughter cells.
Sensitivity of the elastic anisotropy and seismic reflection amplitude of the Eagle Ford Shale to the presence of kerogen
Authors: Sayers Colin M. , Guo Shiguang , Silva Josimar
Published: September 2014

The Eagle Ford Shale of Central and South Texas is currently of great interest for oil and gas exploration and production. Laboratory studies show that the Eagle Ford Shale is anisotropic, with a correlation between anisotropy and total organic carbon. Organic materials are usually more compliant than other minerals present in organic‐rich shales, and their shapes and distribution are usually anisotropic. This makes organic materials an important source of anisotropy in organic‐rich shales. Neglecting shale anisotropy may lead to incorrect estimates of rock and fluid properties derived from inversion of amplitude versus offset seismic data. Organic materials have a significant effect on the PP and PS reflection amplitudes from the Austin Chalk/Upper Eagle Ford interface, the Upper Eagle Ford/Lower Eagle Ford interface, and the Lower Eagle Ford/Buda Limestone interface. The higher kerogen content of the Lower Eagle Ford compared with that of the Upper Eagle Ford leads to a negative PP reflection amplitude that dims with offset, whereas the PS reflection coefficient increases in magnitude with increasing offset. The PP and PS reflection coefficients at the Austin Chalk/Upper Eagle Ford interface, the Upper Eagle Ford/Lower Eagle Ford interface, and the Lower Eagle Ford/Buda Limestone interface all increase in magnitude with increasing volume fraction of kerogen.
Low‐frequency normal wave propagation in a periodically layered medium with weak contrast in elastic properties
Authors: Roganov Y. , Stovas A.
Published: September 2014

We derive the phase velocity dispersion and the scattering for wave vertically propagating in a periodically weak‐contrast horizontally layered medium with arbitrary number of layers in a period. Phase velocity dispersion is defined as the frequency dependence of vertical travel time, and scattering is defined as a reflection coefficient at the interface between the multilayered system and the corresponding Backus medium. Low‐frequency approximation is used to define a dynamic effective medium with frequency‐dependent phase velocity. The results are compared with those obtained earlier for a gradient medium. We show that the low‐frequency weak‐contrast approximation is valid for models with realistic contrasts in elastic properties.
Kite flying: Ancient tradition or death trap?
Authors: Singh Suvir , Peters Nitin James , Samuel Clarence , Bhatti William , Ghosh Dhruv Nath
Published: September 2014

Background

Kite flying has been popular in India since ancient times, especially during harvest festivals of Lohri, Basant and Makar Sankranti. It often takes form of a competitive sport and in recent times has been associated with multiple, sometimes fatal injuries. This prognostic study was conducted to try and understand the epidemiology and factors associated with kite flying injuries in the state of Punjab, India.

Methods

Case reports of patients who presented to the ED with trauma as a result of kite flying were reviewed. The study included patients reporting to the Christian Medical College, Ludhiana, between January 2005 and January 2010. Details of the type and mode of injury, and outcomes were recorded.

Results

The highest incidence of injuries occurred during months of the kite flying festivals. The most common mode of injury was fall from heights, associated with traumatic brain injury. The mortality rate in this series was 6.25%.

Conclusions

This study highlights the importance of kite flying injuries as a common mode of injury in children and adolescents. It is an easily preventable mode of injury with simple safety regulations and possibly stronger legislation.
Target enrichment of ultraconserved elements from arthropods provides a genomic perspective on relationships among Hymenoptera
Authors: Faircloth Brant C. , Branstetter Michael G. , White Noor D. , Brady Seán G.
Published: September 2014

Gaining a genomic perspective on phylogeny requires the collection of data from many putatively independent loci across the genome. Among insects, an increasingly common approach to collecting this class of data involves transcriptome sequencing, because few insects have high‐quality genome sequences available; assembling new genomes remains a limiting factor; the transcribed portion of the genome is a reasonable, reduced subset of the genome to target; and the data collected from transcribed portions of the genome are similar in composition to the types of data with which biologists have traditionally worked (e.g. exons). However, molecular techniques requiring RNA as a template, including transcriptome sequencing, are limited to using very high‐quality source materials, which are often unavailable from a large proportion of biologically important insect samples. Recent research suggests that DNA‐based target enrichment of conserved genomic elements offers another path to collecting phylogenomic data across insect taxa, provided that conserved elements are present in and can be collected from insect genomes. Here, we identify a large set (n = 1510) of ultraconserved elements (UCEs) shared among the insect order Hymenoptera. We used in silico analyses to show that these loci accurately reconstruct relationships among genome‐enabled hymenoptera, and we designed a set of RNA baits (n = 2749) for enriching these loci that researchers can use with DNA templates extracted from a variety of sources. We used our UCE bait set to enrich an average of 721 UCE loci from 30 hymenopteran taxa, and we used these UCE loci to reconstruct phylogenetic relationships spanning very old (≥220 Ma) to very young (≤1 Ma) divergences among hymenopteran lineages. In contrast to a recent study addressing hymenopteran phylogeny using transcriptome data, we found ants to be sister to all remaining aculeate lineages with complete support, although this result could be explained by factors such as taxon sampling. We discuss this approach and our results in the context of elucidating the evolutionary history of one of the most diverse and speciose animal orders.
Satisfaction of patients’ next of kin in a ‘Hub & Spoke’ ICU network
Authors: Chieregato A. , Paci G. , Portolani L. , Ravaldini M. , Fabbri C. , Martino C. , Russo E. , Simini B.
Published: September 2014

This study aimed to gauge the opinions of patients' next of kin regarding transfer of patients from the specialist ‘Hub’ intensive care unit, to ‘Spoke’ intensive care units near home. We included 213 consecutive patients with severe trauma or severe acute neurological conditions admitted to the Hub intensive care unit over a 21‐month period, who were repatriated to Spoke intensive care units for ongoing intensive care. One year after admission to the Hub intensive care unit, two thirds of patients' next of kin said they would have preferred patients to have been treated only in the Hub intensive care unit, and not repatriated. They perceived Hub intensive care unit care to be important, and would have preferred that their relatives be hospitalised there until intensive treatment was completed. The next of kin's preference was associated with severe acute neurological conditions (p ≤ 0.0001). Although centralised Hub & Spoke intensive care unit networks are appropriate to ensure specialised care, repatriation to local hospitals may not be appropriate for patients with severe neurological conditions.
Three‐dimensional ultrasound does not improve diagnosis of retained placental tissue compared to two‐dimensional ultrasound
Authors: Belachew Johanna , Axelsson Ove , Eurenius Karin , Mulic‐Lutvica Ajlana
Published: September 2014

The study objective was to improve ultrasonic diagnosis of retained placental tissue by measuring the volume of the uterine body and cavity using three‐dimensional (3D) ultrasound. Twenty‐five women who were to undergo surgical curettage due to suspected retained placental tissue were included. The volume of the uterine body and cavity was measured using the VOCAL imaging program. Twenty‐one women had retained placental tissue histologically verified. Three of these had uterine volumes exceeding the largest volume observed in the normal puerperium. Seventeen of the 21 women had a uterine cavity volume exceeding the largest volume observed in the normal puerperium. In all 14 cases examined 28 days or more after delivery the cavity volume exceeded the largest volume observed in the normal puerperium. A large cavity volume estimated with 3D ultrasound is indicative of retained placental tissue. However, 3D ultrasound adds little or no diagnostic power compared to 2D ultrasound.