bluuebunny/crossref_metadata_2025 huggingface dataset:
Remarkable isomer-selective gelation of aromatic solvents by a polymorph of a urea-linked bile acid–amino acid conjugate
Authors: Sajisha Valiparambil Sanjayan , Maitra Uday
Published: August 2014

A urea-linked bile acid–amino acid conjugate was developed as a remarkable isomer-selective gelator for various disubstituted aromatic solvents. Polymorphism shown by the urea derivative was studied in detail which showed that only the amorphous polymorph acts as a gelator, but not the crystalline one.
Magneto-optic and converse magnetoelectric effects in a ferromagnetic liquid crystal
Authors: Mertelj Alenka , Osterman Natan , Lisjak Darja , Čopič Martin
Published: August 2014

Schematics of converse magnetoelectric, transverse and parallel magneto-optic effects in a ferromagnetic liquid crystal.
Experimental evidence of soft mode in the smectic C*α phase of chiral ferroelectric liquid crystals
Authors: Hoffmann Jerzy , Nowicka Kamila , Kuczyński Wojciech , Bielejewska Natalia
Published: August 2014

Dielectric properties of chiral smectic liquid crystals characterised by the occurrence of the C*α phase were investigated in the frequency range 10 Hz–1 MHz. In the range of existence of this phase the observed relaxation spectrum is composed of two kinds of mode, and not of a single one, as commonly thought.
Novel gigahertz frequency dielectric relaxations in chitosan films
Authors: Kumar-Krishnan Siva , Prokhorov Evgen , Ramírez Marius , Hernandez-Landaverde Martín A. , Zarate-Triviño Diana G. , Kovalenko Yu , Sanchez Isaac C. , Méndez-Nonell Juan , Luna-Bárcenas Gabriel
Published: August 2014

Temperature-dependence relaxation time of OH side groups versus 1/T for chitosan films in the heating and cooling process. The solid lines represent Arrhenius-type dependence fitting. Schematic of proposed molecular interactions.
Synergistic catalysis of Au–Cu/TiO2-NB nanopaper in aerobic oxidation of benzyl alcohol
Authors: Jia Qinqin , Zhao Dongfang , Tang Bin , Zhao Na , Li Haidong , Sang Yuanhua , Bao Nan , Zhang Xiaomei , Xu Xiaohong , Liu Hong
Published: August 2014

The synergistic catalysis of Au–Cu/TiO2-NB nanostructure synthesized by one-pot photodeposition-galvanic replacement method in benzyl alcohol oxidation.
The synergetic effect of graphene on Cu2O nanowire arrays as a highly efficient hydrogen evolution photocathode in water splitting
Authors: Dubale Amare Aregahegn , Su Wei-Nien , Tamirat Andebet Gedamu , Pan Chun-Jern , Aragaw Belete Asefa , Chen Hong-Ming , Chen Ching-Hsiang , Hwang Bing-Joe
Published: August 2014

The graphene modified Cu2O nanowire array demonstrates improved photocurrent density and photostability, attributed to the synergetic effect of graphene.
Photonic curing of aromatic thiol–ene click dielectric capacitors via inkjet printing
Authors: Riggs Brian C. , Elupula Ravinder , Grayson Scott M. , Chrisey Douglas B.
Published: August 2014

This work ties together the ease of manufacturing through high-throughput techniques and materials processing while increasing performance from conventional methods.
Bendable transparent ZnO thin film surface acoustic wave strain sensors on ultra-thin flexible glass substrates
Authors: Chen Jinkai , He Xingli , Wang Wenbo , Xuan Weipeng , Zhou Jian , Wang Xiaozhi , Dong S. R. , Garner Sean , Cimo Pat , Luo J. K.
Published: August 2014

We demonstrated the flexible SAW sensors based on ultra-thin glass, which have the tremendous capability to detect strains in a very wide range (∼5 times larger than others) with a sensitivity of ∼34.7 Hz με−1.
Proton-associated sucrose transport of mammalian solute carrier family 45: an analysis in Saccharomyces cerevisiae
Authors: Bartölke Rabea , Heinisch Jürgen J. , Wieczorek Helmut , Vitavska Olga
Published: August 2014

The members of the solute carrier 45 (SLC45) family have been implicated in the regulation of glucose homoeostasis in the brain (SLC45A1), with skin and hair pigmentation (SLC45A2), and with prostate cancer and myelination (SLC45A3). However, apart from SLC45A1, a proton-associated glucose transporter, the function of these proteins is still largely unknown, although sequence similarities to plant sucrose transporters mark them as a putative sucrose transporter family. Heterologous expression of the three members SLC45A2, SLC45A3 and SLC45A4 in Saccharomyces cerevisiae confirmed that they are indeed sucrose transporters. [14C]Sucrose-uptake measurements revealed intermediate transport affinities with Km values of approximately 5 mM. Transport activities were best under slightly acidic conditions and were inhibited by the protonophore carbonyl cyanide m-chlorophenylhydrazone, demonstrating an H+-coupled transport mechanism. Na+, on the other hand, had no effect on sucrose transport. Competitive inhibition assays indicated a possible transport also of glucose and fructose. Real-time PCR of mouse tissues confirmed mRNA expression of SLC45A2 in eyes and skin and of SLC45A3 primarily in the prostate, but also in other tissues, whereas SLC45A4 showed a predominantly ubiquitous expression. Altogether the results provide new insights into the physiological significance of SLC45 family members and challenge existing concepts of mammalian sugar transport, as they (i) transport a disaccharide, and (ii) perform secondary active transport in a proton-dependent manner.
Circulating microRNAs: emerging biomarkers for diagnosis and prognosis in patients with gastrointestinal cancers
Authors: Lindner Kirsten , Haier Joerg , Wang Zhe , Watson David I. , Hussey Damian J. , Hummel Richard
Published: August 2014

To identify novel non-invasive biomarkers for improved detection, risk assessment and prognostic evaluation of cancer, expression profiles of circulating microRNAs are currently under evaluation. Circulating microRNAs are highly promising candidates in this context, as they present some key characteristics for cancer biomarkers: they are tissue-specific with reproducible expression and consistency among individuals from the same species, they are potentially derived directly from the tumour and therefore might correlate with tumour progression and recurrence, and they are bound to proteins or contained in subcellular particles, such as microvesicles or exosomes, making them highly stable and resistant to degradation. The present review highlights the origin of circulating microRNAs, their stability in blood samples, and techniques to isolate exosomal microRNAs, and then addresses the current evidence supporting potential clinical applications of circulating miRNAs for diagnostic and prognostic purposes.
Comparison of several data‐driven non‐linear system identification methods on a simplified glucoregulatory system example
Authors: Marconato Anna , Schoukens Maarten , Tiels Koen , Widanage Widanalage Dhammika , Abu‐Rmileh Amjad , Schoukens Johan
Published: August 2014

In this study, several advanced data‐driven non‐linear identification techniques are compared on a specific problem: a simplified glucoregulatory system modelling example. This problem represents a challenge in the development of an artificial pancreas for Type 1 diabetes mellitus treatment, since for this application good non‐linear models are needed to design accurate closed‐loop controllers to regulate the glucose level in the blood. Block‐oriented as well as state‐space models are used to describe both the dynamics and the non‐linear behaviour of the insulin–glucose system, and the advantages and drawbacks of each method are pointed out. The obtained non‐linear models are accurate in simulating the patient's behaviour, and some of them are also sufficiently simple to be considered in the implementation of a model‐based controller to develop the artificial pancreas.
Topology assessment for 3 + 3 terminal offshore DC grid considering DC fault management
Authors: Jovcic Dragan , Taherbaneh Mohsen , Taisne Jean Pierre , Nguefeu Samuel
Published: August 2014

This study assesses four DC grid topologies where each of the terminals can exchange power with any other terminal and a DC fault on any DC cable can be isolated. The DC grids are built using the following components: hybrid DC circuit breakers (CB), mechanical DC CBs, DC/DC converters and DC hubs. The aim is to compare DC fault performance, technical feasibility/readiness, power transfer security, expansion and costs. The base case for comparison are three separate 300 km offshore HVDCs connecting 3 1 GW offshore wind farms with three onshore VSC terminals. The rating of DC CBs is limited by the state of technology and costs which introduces limitation on the length of DC cables (because of communication delays) and on the DC bus fault level (limiting the number of connecting DC lines). DC/DC converters inherently block propagation of DC faults and their rating is not sensitive to DC fault level. DC hubs have considerable cost advantages over multiple DC/DC converters in cases where multiple DC systems are connecting at the same DC station. The cost assumptions for all major components are analysed, including the offshore platform costs. The study concludes that overall DC grid costs are similar (within 8%) for all four topologies. Although power security is similar for all technologies, the expansion options are best with DC/DC converters or DC hubs. DC hubs nevertheless suffer from highest on‐state losses.
Criterion to evaluate power system online transient stability based on adjoint system energy function
Authors: Zhao Shuai , Jia Hongjie , Fang Dazhong , Jiang Yilang , Kong Xiangyu
Published: August 2014

In this paper, a new criterion to quickly evaluate the system transient stability based on wide area measurement system (WAMS) information, energy function method and adjoint power system (APS) model is proposed. APS is a two‐dimensional‐first‐order differential equation model, which can be considered as a virtual representation to the real power system. Meaning of APS is first explained by using the one machine infinite bus system. Then, a new criterion based on projection kinetic energy of APS is proposed to determine the transient stability of the original power system with multiple generators. Trajectory prediction method based on curve fitting technique is adopted to accelerate the evaluation process. The proposed method is sufficiently rapid since it does not rely on the network structure, system model, system parameters and the identification of the coherent generator groups. Therefore, it can be utilised for online transient stability assessment based on WAMS. Simulation results on the New England system and one of North China Power System validate the correctness and effectiveness of the proposed method.
Tool for testing of phasor measurement units: PMU performance analyser
Authors: Biswas Saugata S. , Srivastava Anurag K. , Park Joshua S. , Castaneda Juan
Published: August 2014

Phasor measurement units (PMUs) are one of the key sensor technologies for real‐time wide area monitoring to realise the smart power grid vision. Before deploying the PMUs, it is important to test and validate performance of this sensor to ensure high reliability and accuracy under different operating scenarios of the power system. However, PMU testing needs to be made simpler, easier, automated and cost‐effective to encourage the PMU vendors and utilities to get their PMUs tested. This has been the driving motivation for the development of a new procedure and tool for testing PMUs in this study. The results and findings of PMU testing and analysis using a newly developed software application named ‘PMU Performance Analyzer' (PPA) have been discussed in this study. PPA can work with a real‐time digital simulator and a phasor data concentrator to make the PMU testing simple, easy, mostly automated, less time‐consuming, highly accurate and cost‐effective.
Evaluating radiation efficiency from characteristic currents
Authors: Capek Miloslav , Eichler Jan , Hazdra Pavel
Published: August 2014

This study describes an effective technique for calculating modal radiation efficiency calculation based on decomposition into characteristic modes. The key assumption is that the current distribution on the perfect electric conductor is almost the same as in the case of a very good conductor, for example, metals such as copper, aluminium and silver. This assumption is verified against the conventional technique, the impedance boundary condition (IBC). The proposed approach does not require any modification of the formulation of method of moments for perfectly conducting surfaces, which is assumed for the modal decomposition. Modal efficiencies provide an additional insight that is useful especially for the design of small antennas. Taking the feeding into account, the modal losses can be summed up to obtain the total efficiency. The technique works perfectly for common metals, is fully comparable with the IBC, and can easily be incorporated into any present‐day in‐house solver. A numerical analysis of three antennas is presented to demonstrate the merits of the approach. Radiation efficiency of coupled dipoles, an electrically small meandered dipole, and PIFA were investigated by the presented method. The results are in perfect agreement with the reference commercial package.
Dual band‐notched monopole antenna with enhanced bandwidth for ultra‐wideband wireless communications
Authors: Akbari Mohammad , Rojhani Neda , Saberi Mehdi , Movahedinia Reza
Published: August 2014

A new configuration of an ultra‐wideband (UWB) dual band‐notched antenna is presented. The designed geometry consists of octagonal radiating patch, a 50 Ω microstrip feed‐line on the front and an asymmetric partial ground on the back. For impedance bandwidth enhancement, a unilateral stepped structure is utilised on the ground. By etching two E‐shaped slots connected to each other on the radiating patch and applying E‐shaped defected ground structure on the back, dual notched bands are achieved. The antenna is printed on a low profile FR4 substrate with a compact size of 25 × 18 × 1 mm3. The experimental results indicate that the antenna has an impedance bandwidth from 2.55 to 21.65 GHz for voltage standing wave ratio ≤2, except the notched bands on worldwide interoperability for microwave access and wireless local area network bands. Moreover, stable radiation patterns and gains within the operating band are shown.
Fixed capacity and variable member grouping assignment of orthogonal variable spreading factor code tree for code division multiple access networks
Authors: Balyan Vipin , Saini Davinder S , Mehta Ankit
Published: August 2014

Orthogonal variable spreading factor codes are used in the downlink to maintain the orthogonality between different channels and are used to handle new calls arriving in the system. A period of operation leads to fragmentation of vacant codes. This leads to code blocking problem. The assignment scheme proposed in this paper is not affected by fragmentation, as the fragmentation is generated by the scheme itself. In this scheme, the code tree is divided into groups whose capacity is fixed and numbers of members (codes) are variable. A group with maximum number of busy members is used for assignment, this leads to fragmentation of busy groups around code tree and compactness within group. The proposed scheme is well evaluated and compared with other schemes using parameters like code blocking probability and call establishment delay. Through simulations it has been demonstrated that the proposed scheme not only adequately reduces code blocking probability, but also requires significantly less time before assignment to locate a vacant code for assignment, which makes it suitable for the real‐time calls.
Mathematical analysis for detection probability in cognitive radio networks over wireless communication channels
Authors: Ujjinimatad Rohitha , Patil Siddarama R.
Published: August 2014

In this study, the authors consider the problem of spectrum sensing based on energy detection method in cognitive radio over wireless communication channels when users experience fading and non‐fading effects. The closed‐form analytical expressions for the detection probability are derived over non‐fading additive white Gaussian noise channel and Rayleigh and log‐normal shadowing fading channels. The detection probability involves Marcum‐Q function, summations and integrations in the early research papers, which are replaced by closed‐form expressions in this study. The probability distribution function of fading channels is used to obtain the expressions for detection probability. The new derived numerical results are simulated under various parameters. The performance of the derived theoretical expressions closely matches with the simulated results.
Conceptual design of the gamma-to-electron magnetic spectrometer for the National Ignition Facility
Authors: Kim Y. , Herrmann H. W. , Jorgenson H. J. , Barlow D. B. , Young C. S. , Stoeffl W. , Casey D. , Clancy T. , Lopez F. E. , Oertel J. A. , Hilsabeck T. , Moy K. , Batha S. H.
Published: August 2014

The Gamma-to-Electron Magnetic Spectrometer (GEMS) diagnostic is designed to measure the prompt γ-ray energy spectrum during high yield deuterium-tritium (DT) implosions at the National Ignition Facility (NIF). The prompt γ-ray spectrum will provide “burn-averaged” observables, including total DT fusion yield, total areal density (ρR), ablator ρR, and fuel ρR. These burn-averaged observables are unique because they are essentially averaged over 4π, providing a global reference for the line-of-sight-specific measurements typical of x-ray and neutron diagnostics. The GEMS conceptual design meets the physics-based requirements: ΔE/E = 3%–5% can be achieved in the range of 2–25 MeV γ-ray energy. Minimum DT neutron yields required for 15% measurement uncertainty at low-resolution mode are: 5 × 1014 DT-n for ablator ρR (at 0.2 g/cm2); 2 × 1015 DT-n for total DT yield (at 4.2 × 10−5 γ/n); and 1 × 1016 DT-n for fuel ρR (at 1 g/cm2).
Validity of virial theorem in all-electron mixed basis density functional, Hartree–Fock, and GW calculations
Authors: Kuwahara Riichi , Tadokoro Yoichi , Ohno Kaoru
Published: August 2014

In this paper, we calculate kinetic and potential energy contributions to the electronic ground-state total energy of several isolated atoms (He, Be, Ne, Mg, Ar, and Ca) by using the local density approximation (LDA) in density functional theory, the Hartree–Fock approximation (HFA), and the self-consistent GW approximation (GWA). To this end, we have implemented self-consistent HFA and GWA routines in our all-electron mixed basis code, TOMBO. We confirm that virial theorem is fairly well satisfied in all of these approximations, although the resulting eigenvalue of the highest occupied molecular orbital level, i.e., the negative of the ionization potential, is in excellent agreement only in the case of the GWA. We find that the wave function of the lowest unoccupied molecular orbital level of noble gas atoms is a resonating virtual bound state, and that of the GWA spreads wider than that of the LDA and thinner than that of the HFA.
Invited Review Article: Development of crystal lenses for energetic photons
Authors: Smither Robert K.
Published: August 2014

This paper follows the development of crystal diffraction lenses designed to focus energetic photons. It begins with the search for a solution to the astrophysics problem of how to detect weak astrophysics sources of gamma rays and x-rays. This led to the basic designs for a lens and to the understanding of basic limitations of lens design. The discussion of the development of crystal diffraction lenses is divided into two parts: lenses using crystals with mosaic structure, and lenses that use crystals with curved crystal planes. This second group divides into two sub-groups: (1) Curved crystals that are used to increase the acceptance angle of the diffraction of a monochromatic beam and to increase the energy bandwidth of the diffraction. (2) Curved crystals used to focus gamma ray beams. The paper describes how these two types of crystals affect the design of the corresponding crystal lenses in different fields: astrophysics, medical imaging, detection of weak, distant, gamma-ray sources, etc. The designs of crystal lenses for these applications are given in enough detail to allow the reader to design a lens for his own application.
Spectral encoding method for measuring the relative arrival time between x-ray/optical pulses
Authors: Bionta M. R. , Hartmann N. , Weaver M. , French D. , Nicholson D. J. , Cryan J. P. , Glownia J. M. , Baker K. , Bostedt C. , Chollet M. , Ding Y. , Fritz D. M. , Fry A. R. , Kane D. J. , Krzywinski J. , Lemke H. T. , Messerschmidt M. , Schorb S. , Zhu D. , White W. E. , Coffee R. N.
Published: August 2014

The advent of few femtosecond x-ray light sources brings promise of x-ray/optical pump-probe experiments that can measure chemical and structural changes in the 10–100 fs time regime. Widely distributed timing systems used at x-ray Free-Electron Laser facilities are typically limited to above 50 fs fwhm jitter in active x-ray/optical synchronization. The approach of single-shot timing measurements is used to sort results in the event processing stage. This has seen wide use to accommodate the insufficient precision of active stabilization schemes. In this article, we review the current technique for “measure-and-sort” at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The relative arrival time between an x-ray pulse and an optical pulse is measured near the experimental interaction region as a spectrally encoded cross-correlation signal. The cross-correlation provides a time-stamp for filter-and-sort algorithms used for real-time sorting. Sub-10 fs rms resolution is common in this technique, placing timing precision at the same scale as the duration of the shortest achievable x-ray pulses.
Enhanced performance of polymer:fullerene bulk heterojunction solar cells upon graphene addition
Authors: Robaeys Pieter , Bonaccorso Francesco , Bourgeois Emilie , D'Haen Jan , Dierckx Wouter , Dexters Wim , Spoltore Donato , Drijkoningen Jeroen , Liesenborgs Jori , Lombardo Antonio , Ferrari Andrea C. , Van Reeth Frank , Haenen Ken , Manca Jean V. , Nesladek Milos
Published: August 2014

Graphene has potential for applications in solar cells. We show that the short circuit current density of P3HT (Poly(3-hexylthiophene-2,5-diyl):PCBM((6,6)-Phenyl C61 butyric acid methyl ester) solar cells is enhanced by 10% upon the addition of graphene, with a 15% increase in the photon to electric conversion efficiency. We discuss the performance enhancement by studying the crystallization of P3HT, as well as the electrical transport properties. We show that graphene improves the balance between electron and hole mobilities with respect to a standard P3HT:PCBM solar cell.
Location deterministic biosensing from quantum-dot-nanowire assemblies
Authors: Liu Chao , Kim Kwanoh , Fan D. L.
Published: August 2014

Semiconductor quantum dots (QDs) with high fluorescent brightness, stability, and tunable sizes, have received considerable interest for imaging, sensing, and delivery of biomolecules. In this research, we demonstrate location deterministic biochemical detection from arrays of QD-nanowire hybrid assemblies. QDs with diameters less than 10 nm are manipulated and precisely positioned on the tips of the assembled Gold (Au) nanowires. The manipulation mechanisms are quantitatively understood as the synergetic effects of dielectrophoretic (DEP) and alternating current electroosmosis (ACEO) due to AC electric fields. The QD-nanowire hybrid sensors operate uniquely by concentrating bioanalytes to QDs on the tips of nanowires before detection, offering much enhanced efficiency and sensitivity, in addition to the position-predictable rationality. This research could result in advances in QD-based biomedical detection and inspires an innovative approach for fabricating various QD-based nanodevices.
Control of optical properties of hybrid materials with chirped femtosecond laser pulses under strong coupling conditions
Authors: Sukharev Maxim
Published: August 2014

The interaction of chirped femtosecond laser pulses with hybrid materials—materials comprised of plasmon sustaining structures and resonant molecules—is scrutinized using a self-consistent model of coupled Maxwell-Bloch equations. The optical properties of such systems are examined with the example of periodic sinusoidal gratings. It is shown that under strong coupling conditions one can control light transmission using chirped pulses in a spatiotemporal manner. The temporal origin of control relies on chirps non-symmetric in time while the space control is achieved via spatial localization of electromagnetic energy due to plasmon resonances.
Study on multicaloric effect of CuO induced multiferroic
Authors: Kumar Amit , Yadav K. L.
Published: August 2014

One of the induced multiferroic materials, CuO has the magnetic as well as ferroelectric phase transition at same temperature (TN1 ∼ 213 K, TC and TN2 ∼ 230 K). These type of materials can show two types of entropy; magnetic field induced entropy (Magnetocaloric Effect) as well as electeric field induced entropy (Electrocaloric Effect). The presence of both type of entropy may be called “Multicaloric Entropy” (M. Vopson, Solid State Commun. 152, 2067 (2012) and Meng et al., Phys. Lett. A 377, 567 (2013)). We observed that “Multicaloric Entropy” in the induced multiferroic materials also depends on the magnetoelectric interaction (γ). Therofore, this numerical attempt to calculate the entropy of CuO may be useful for the future “electro-magnetic” based refrigerator technology.
On the applicability of the standard kinetic theory to the study of nanoplasmas
Authors: D'Angola A. , Boella E. , Coppa G.
Published: August 2014

Kinetic theory applies to systems with a large number of particles, while nanoplasma generated by the interaction of ultra–short laser pulses with atomic clusters are systems composed by a relatively small number (102 ÷ 104) of electrons and ions. In the paper, the applicability of the kinetic theory for studying nanoplasmas is discussed. In particular, two typical phenomena are investigated: the collisionless expansion of electrons in a spherical nanoplasma with immobile ions and the formation of shock shells during Coulomb explosions. The analysis, which is carried out comparing ensemble averages obtained by solving the exact equations of motion with reference solutions of the Vlasov-Poisson model, shows that for the dynamics of the electrons the error of the usually employed models is of the order of few percents (but the standard deviation in a single experiment can be of the order of 10%). Instead, special care must be taken in the study of shock formation, as the discrete structure of the electric charge can destroy or strongly modify the phenomenon.
Determination of thermal and photothermal properties of an amorphous GaSe9 alloy
Authors: Siqueira M. C. , Maia R. N. A. , Araujo R. M. T. , Machado K. D. , Stolf S. F. , de Lima J. C. , Poffo C. M.
Published: August 2014

We investigated the thermal and photothermal properties of an amorphous GaSe9 alloy produced by mechanical alloying considering the photoacoustic spectroscopy and differential scanning calorimetry (DSC) techniques. The room temperature thermal diffusivity of GaSe9 was determined using the open photoacoustic cell configuration considering the thermal diffusion and thermoelastic bending effects. The glass transition and crystallization processes were investigated through DSC measurements obtained at five heating rates, and glass transition, crystallization temperatures, and activation energies were determined. The crystallization mechanism was also determined.
Low-temperature phase transitions in a soluble oligoacene and their effect on device performance and stability
Authors: Ward J. W. , Goetz K. P. , Obaid A. , Payne M. M. , Diemer P. J. , Day C. S. , Anthony J. E. , Jurchescu O. D.
Published: August 2014

The use of organic semiconductors in high-performance organic field-effect transistors requires a thorough understanding of the effects that processing conditions, thermal, and bias-stress history have on device operation. Here, we evaluate the temperature dependence of the electrical properties of transistors fabricated with 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene, a material that has attracted much attention recently due to its exceptional electrical properties. We have discovered a phase transition at T = 205 K and discuss its implications on device performance and stability. We examined the impact of this low-temperature phase transition on the thermodynamic, electrical, and structural properties of both single crystals and thin films of this material. Our results show that while the changes to the crystal structure are reversible, the induced thermal stress yields irreversible degradation of the devices.
Exchange bias effect in epitaxial La0.67Ca0.33MnO3/SrMnO3 thin film structure
Authors: Yu T. , Ning X. K. , Liu W. , Feng J. N. , Zhao X. G. , Zhang Z. D.
Published: August 2014

Bilayers consisting of La0.67Ca0.33MnO3 (LCMO) and SrMnO3 (SMO) have been prepared by pulsed-laser deposition on SrTiO3 (001) substrates. Unconventional magnetic coupling was found after cooling in a small field. The LCMO/SMO bilayers exhibit an exchange bias field of 209 Oe, which vanishes as the temperature rises above 90 K. A small magnetization has been found above the Curie temperature of the pure LCMO thin films. Spin-cluster-like antiferromagnetic (AFM)/ferromagnetic (FM) clusters have been deduced to exist at the interface due to the competing types of magnetic order at the interface. The magnetic relaxation is found to follow a double-exponential equation and a slow relaxation process is observed due to the strong exchange coupling between AFM/FM clusters and the LCMO layer. We speculate that the short-range high-temperature FM order of the Mn3+ and Mn4+ moments above the Curie temperature at the interface gives rise to the magnetic regions that pin the FM LCMO layer as the temperature decreases.
Acoustic transistor: Amplification and switch of sound by sound
Authors: Liang Bin , Kan Wei-wei , Zou Xin-ye , Yin Lei-lei , Cheng Jian-chun
Published: August 2014

We designed an acoustic transistor to manipulate sound in a manner similar to the manipulation of electric current by its electrical counterpart. The acoustic transistor is a three-terminal device with the essential ability to use a small monochromatic acoustic signal to control a much larger output signal within a broad frequency range. The output and controlling signals have the same frequency, suggesting the possibility of cascading the structure to amplify an acoustic signal. Capable of amplifying and switching sound by sound, acoustic transistors have various potential applications and may open the way to the design of conceptual devices such as acoustic logic gates.
Single photon emission of a charge-tunable GaAs/Al0.25Ga0.75As droplet quantum dot device
Authors: Langer Fabian , Plischke David , Kamp Martin , Höfling Sven
Published: August 2014

In this work, we report the fabrication of a charge-tunable GaAs/Al0.25Ga0.75As quantum dot (QD) device containing QDs deposited by modified droplet epitaxy producing almost strain and composition gradient free QDs. We obtained a QD density in the low 109 cm−2 range that enables us to perform spectroscopy on single droplet QDs showing linewidths as narrow as 40 μeV. The integration of the QDs into a Schottky diode allows us to controllably charge a single QD with up to four electrons, while non-classical photoluminescence is proven by photon auto-correlation measurements showing photon-antibunching (g(2)(0) = 0.05).
Experimental evidence for the bending of heat flux in a thermal metamaterial
Authors: Yang Tianzhi , Vemuri Krishna P. , Bandaru Prabhakar R.
Published: August 2014

Multilayered oriented composites constituted from two materials of different thermal conductivities are shown to have the ability to direct thermal energy. The composites behave as effective media with anisotropic thermal conductivity. The guiding of the heat flux is shown experimentally with bending angle ranging from ∼25° to the maximum possible value of ∼45° (for the considered prototypical composites) with respect to a horizontal temperature gradient—in excellent accord with theoretical estimates and computational simulations. Such thermal metamaterials lay the basis for efficient manipulation of heat and for thermal elements, such as thermal concentrators and cloaks.
Manipulation of graphene work function using a self-assembled monolayer
Authors: Seo Jung-Tak , Bong Jihye , Cha Janghwan , Lim Taekyung , Son Junyoung , Park Sung Ha , Hwang Jungseek , Hong Suklyun , Ju Sanghyun
Published: August 2014

We report an effective and reliable method to increase the work function of graphene to as high as 5.50 eV by applying a self-assembled monolayer on its surface. The work function of pristine graphene (4.56 eV) was increased by approximately +0.94 eV following trichlorosilane (HDF-S) self-assembly. This increase in the work function was confirmed by ab initio calculations. HDF-S self-assembled graphene exhibited no significant changes in structural, optical, or electrical characteristics compared with pristine graphene. In addition, we verified that the modified work function of HDF-S self-assembled graphene was not affected by the underlying substrates.
Hydrogenation of GaSb/GaAs quantum rings
Authors: Hodgson P. D. , Hayne M. , Ahmad Kamarudin M. , Zhuang Q. D. , Birindelli S. , Capizzi M.
Published: August 2014

We present the results of photoluminescence measurements on hydrogenated type-II GaSb/GaAs quantum dot/ring (QD/QR) samples at temperatures ranging from 4.2 K to 400 K. Hydrogenation is found to suppress optically induced charge depletion (associated with the presence of carbon acceptors in this system). A redshift of the QD\QR emission energy of a few tens of meV is observed at temperatures ≥300 K, consistent with a reduction in average occupancy by ∼1 hole. These effects are accompanied by a reduction in PL intensity post-hydrogenation. We conclude that although hydrogenation may have neutralized the carbon acceptors, multiple hole occupancy of type-II GaSb/GaAs QD/QRs is very likely a precondition for intense emission, which would make extending the wavelength significantly beyond 1300 nm at room temperature difficult.
The effects of non-uniform loss on time reversal mirrors
Authors: Taddese Biniyam Tesfaye , Antonsen Thomas M. , Ott Edward , Anlage Steven M.
Published: August 2014

Time reversal mirrors work perfectly only for lossless wave propagation; dissipation destroys time-reversal invariance and limits the performance of time-reversal mirrors. Here, a new measure of time-reversal mirror performance is introduced and the adverse effect of dissipation on this performance measure is investigated. The technique of exponential amplification is employed to partially overcome the effect of non-uniform loss distributions, and its success is tested quantitatively using the new performance measure. A numerical model of a star graph is employed to test the applicability of this technique on realizations with various random spatial distributions of loss. A subset of the numerical results are also verified by experimental results from an electromagnetic time-reversal mirror. The exponential amplification technique is a simple way to improve the performance of emerging technologies based on time-reversed wave propagation such as directed communication and wireless power transfer.
Impact of symmetry in transport properties of graphene nanoribbons with defects
Authors: Kvashnin D. G. , Chernozatonskii L. A.
Published: August 2014

We report a theoretical investigation of the impact of asymmetry in the geometry of graphene nanoribbons (GNR) on the current-voltage characteristics caused by introducing the structural defects using ab initio methods. Only the most possible structural defects were considered: mono vacancy, Stone-Wales (SW) defect with different orientation, and partial hydrogen passivation on the GNR surface. It is found that in case of SW defects the value of current is four times higher at the negative voltage than in case of structures with mono vacancy defect. Also, the impact of orientation of the SW defect on the I-V characteristics was studied.
Effects of In profile on simulations of InGaN/GaN multi-quantum-well light-emitting diodes
Authors: McBride Patrick M. , Yan Qimin , Van de Walle Chris G.
Published: August 2014

We investigate the impact of incorporating realistic In profiles in simulations of c-plane InGaN/GaN light-emitting diodes. Simulations based on a drift-diffusion model typically overestimate the onset voltage, but have usually been based on the assumption of ideal quantum wells with a square In profile. We demonstrate that more realistic profiles lead to significant modifications of current-density-versus-voltage characteristics, and explain the effects based on changes in the band diagram and carrier overlap.
Experimental measurement of vapor density in the discharge channel of a pulsed positive streamer discharge in water
Authors: Wen Xiao Qiong , Li Shu Han , Liu Jin Yuan , Niu Zhi Wen
Published: August 2014

Using the shadowgraph technique, we performed direct measurements of the vapor density in the discharge channel of a pulsed positive streamer discharge in water. With this experimental technique, we quantitatively measured the vapor density in the discharge channel of a pulsed positive streamer discharge in water of conductivity 100 μS/cm. The results show that the vapor density in the discharge channel ranges from 100 to 660 kg/m3, and presents an increasing tendency along the axial direction of the discharge channel with increasing distance from the tip of the anode.
Comparison of in vivo and in silico growth performance and variability in pigs when applying a feeding strategy designed by simulation to control the variability of slaughter weight
Authors: Brossard L. , Vautier B. , van Milgen J. , Salaun Y. , Quiniou N.
Published: August 2014

Variability in bodyweight (BW) among pigs complicates the management of feeding strategies and slaughter. Including variability among individuals in modelling approaches can help to design feeding strategies to control performance level, but also its variability. The InraPorc model was used to perform simulations on 10 batches of 84 crossbred pigs each to characterise the effect of feeding strategies differing in amino acid supply or feed allowance on the mean and variation in growth rate. Results suggested that a feed restriction reduces the coefficient of variation of BW at first departure for slaughter (BW1) by 34%. Growth performance obtained from an in silico simulation using ad libitum and restricted feeding plans was compared with results obtained in an in vivo experiment on a batch of 168 pigs. Pigs were offered feed ad libitum or were restricted (increase in feed allowance by 27 g/day up to a maximum of 2.4 and 2.7 kg/day for gilts and barrows, respectively). A two-phase feeding strategy was applied, with 0.9 and 0.7 g of digestible lysine per MJ of net energy (NE) in diets provided before or after 65 kg BW, respectively. Actual growth was similar to that obtained by simulation. Coefficient of variation of BW1 was similar in vivo and in silico for the ad libitum feeding strategy but was underestimated by 1 percentage point in silico for the restriction strategy. This study confirms the relevance of using simulations performed to predict the level and variability in performance of group housed pigs.
The challenges and opportunities when integrating animal models into grazing system models for evaluating productivity and environmental impact
Authors: Eckard R. J. , Snow V. O. , Johnson I. R. , Moore A. D.
Published: August 2014

The intensification of livestock production has highlighted the importance of balancing production and the environmental impact in grazing systems. With the advent of more distributed computing power we have seen more complex models being developed, capable of simulating most aspects of a livestock production system. Where the modelling objective includes prediction of both productivity and environmental impacts, it is imperative to include appropriate consideration of the grazing animal in the simulation. This raises numerous challenges with respect to environmental impact modelling, including explicit treatment of nutrients in dung and urine, the prediction of grazing behaviour, dry matter intake and associated enteric methane loss. This paper discusses these challenges and opportunities when integrating animal models into grazing system models for evaluating productivity and environmental impact.
Viruses of New Zealand pasture grasses and legumes: a review
Authors: Guy P. L.
Published: August 2014

This article reviews knowledge of 23 plant viruses infecting pasture grasses and legumes in New Zealand. The incidence, ecology and impact of each virus and prospects for control using natural or artificial resistance genes or by vector control is discussed. The most prevalent viruses are Alfalfa mosaic virus and White clover mosaic virus in pasture legumes and Cocksfoot mottle virus, Ryegrass mosaic virus and Barley yellow dwarf virus in pasture grasses. Lucerne Australian latent virus is restricted to the North Island and Red clover necrotic mosaic virus is largely restricted to the South Island. These patterns are likely to be dynamic with ongoing changes in weather patterns, land use, the spread of insect vectors and the continuing introduction of viruses and vectors. The existing and potential threats to 12 pasture species are tabulated and the knowledge gaps for each species highlighted. Control of vectors including aphids, eriophyid mites and soil-borne fungi is probably not economic per se but could be an additional benefit of integrated pest management in pasture and cropping systems. The most cost-effective and practical preventative measures are likely to be the use of virus-tested seed to establish new pastures and the incorporation of resistance genes by conventional breeding or by genetic engineering. Finally, recommendations are made for future research for New Zealand, which is also relevant to other temperate regions of the world.
The Language of Emotions
Authors: Ponsonnet Maïa
Published: August 2014

The Language of Emotions: The case of Dalabon (Australia) is the first extensive study of the linguistic encoding of emotions in an Australian language, and further, in an endangered, non-European language. Based on first-hand data collected using innovative methods, the monograph describes and analyzes how Dalabon speakers express emotions (using interjections, prosody, evaluative morphology) and the words they use to describe and discuss emotions. Like many languages, Dalabon makes broad use of body-part words in descriptions of emotions. The volume analyzes the figurative functions of these body-part words, as well as their non-figurative functions. Correlations between linguistic features and cultural patterns are systematically questioned.
Beyond Australianists and linguists working on emotions, the book will be of interest to anthropological linguists, cognitive linguists, or linguists working on discourse and communication for instance. It is accessible also to non-linguists with an interest in language, in particular anthropologists and psychologists.
Convergence and endonormativity at Phase Four of the Dynamic Model
Authors: van Rooy Bertus
Published: August 2014

At Phase 4 of the Dynamic Model, Schneider (2007) postulates that a stable postcolonial English will gain acceptance in a country, and become endonormative, but it will also be perceived as homogenous. This paper argues that, in a postcolonial language contact situation, multiple contact settings give rise to different postcolonial Englishes, which will not necessarily converge. The number of contact settings should correspond closely to the number of stabilising varieties. Endonormativity will result from identity rewriting, and this should typically happen for an entire country, or at least for the dominant group of English speakers. These refinements on the Dynamic Model are presented with evidence from the United States of America and South Africa, two less typical settings due to the complexity of their population demographics.
The sociophonetic effects of Event X
Authors: Mesthrie Rajend
Published: August 2014

South Africa offers an ecological complexity that challenges World Englishes theorizing. The number of speakers of the Settler variety remains relatively large, and other L1 varieties play an important role in public life (primarily those spoken by Indian and Coloured speakers). In addition there is a growing trend towards the acquisition of the prestige variant of South African English by young middle-class Black speakers. But there are intermediate varieties which have arisen and are flourishing in the new post-apartheid openness. This paper offers a close analysis of Black speakers who have been influenced by the norms of Indian and Coloured counterparts, especially within an informal educational context. The implications of such multicultural contact within the Schneider’s Dynamic Model are explored.
Beyond Nativization? Philippine English in Schneider's Dynamic Model
Authors: Pefianco Martin Isabel
Published: August 2014

According to Schneider (2007), the development of Philippine English (PE) is unique in that the language was brought to the country through American, and not British, colonial expansion. Whereas Outer Circle countries in Southeast Asia, such as Malaysia, took about two hundred years to move from Phase 1 to Phase 3 of the Dynamic Model, English in the Philippines evolved to a state of Nativization in fewer than a hundred years. In this chapter, I explore the issue of PE as remaining restricted in Phase 3 and thus, “coming to a halt” in the Nativization Phase (Schneider 2007: 143) of the model. Or, as some have claimed, has PE progressed beyond Nativization and developed into a variety of Endonormative Stabilization?
English in Germany
Authors: Kautzsch Alexander
Published: August 2014

Even if linguistic research (e.g. Berns 1988; Hilgendorf 2005) has claimed that the status of English in Germany might be changing from foreign language (EFL) to second language (ESL) status, or, for that matter, from an Expanding Circle to an Outer Circle English (e.g. Kachru 1985), empirical evidence is sparse. The present study addresses this gap by presenting different types of empirical data which tackle three issues relevant for describing the status of English: spreading bilingualism, exonormative orientation and the nativization of pronunciation features. In addition it is shown how the categorization of English spoken in non-postcolonial settings can profit from the basic notions of Schneider’s Dynamic Model for postcolonial Englishes and thus go beyond the tradition static terms ESL, EFL and the like.
On cafeterias and new dialects
Authors: Schreier Daniel
Published: August 2014

This chapter argues that we need to differentiate potential founding populations in high-contact scenarios and classify different types of transmitters. Based on evidence from South Atlantic English, the claim is that, during the formative years of new dialects, some members of the community are more crucial than others, simply because they are more likely to transmit features to young children given their social role in the community. The impact of so-called primary transmitters may help explain why some dialects are extraordinarily influential in contact scenarios, despite the fact that its speakers represent a minority. This calls for a revision of current theories of new-dialect formation and for a more socially-informed view of koinéization processes.