bluuebunny/crossref_metadata_2025 huggingface dataset:
A new approach for fabricating germanene with Dirac electrons preserved: a first principles study
Authors: Li Ping , Cao Juexian , Guo Zhi-Xin
Published: January 2016

We propose a new approach to fabricating germanene in which the Dirac electronic properties are preserved very well.
Subcellular behaviour evaluation of nanopharmaceuticals with aggregation-induced emission molecules
Authors: Xue Xiangdong , Xu Jing , Wang Paul C. , Liang Xing-Jie
Published: January 2016

Aggregation-induced emission molecules based nanopharmaceuticals enable to not only deliver the therapeutic agents, but also decipher their innate intracellular or subcellular behaviours.
Uranium-induced rat kidney cell cytotoxicity is mediated by decreased endogenous hydrogen sulfide (H2S) generation involved in reduced Nrf2 levels
Authors: Yuan Yan , Zheng Jifang , Zhao Tingting , Tang Xiaoqing , Hu Nan
Published: January 2016

The mechanism of uranium-induced kidney cell cytotoxicity is not fully understood.
Correction: Effects of Ga–Te interface layer on the potential barrier height of CdTe/GaAs heterointerface
Authors: Xi Shouzhi , Jie Wanqi , Zha Gangqiang , Yuan Yanyan , Wang Tao , Zhang Wenhua , Zhu Junfa , Xu Lingyan , Xu Yadong , Su Jie , Zhang Hao , Gu Yaxu , Li Jiawei , Ren Jie , Zhao Qinghua
Published: January 2016

Correction for ‘Effects of Ga–Te interface layer on the potential barrier height of CdTe/GaAs heterointerface’ by Shouzhi Xi et al., Phys. Chem. Chem. Phys., 2016, 18, 2639–2645.
Correction: Alkynyl-functionalized gold NHC complexes and their coinage metal clusters
Authors: Kiefer Claude , Bestgen Sebastian , Gamer Michael T. , Lebedkin Sergei , Kappes Manfred M. , Roesky Peter W.
Published: January 2016

Correction for ‘Alkynyl-functionalized gold NHC complexes and their coinage metal clusters’ by Claude Kiefer et al., Dalton Trans., 2015, 44, 13662–13670.
Comparing the suitability of sodium hyposulfite, hydroxylamine hydrochloride and sodium sulfite as the quenching agents for permanganate oxidation
Authors: Sun Bo , Rao Dandan , Dong Hongyu , Guan Xiaohong
Published: January 2016

The graphic abstract showed the quenching efficiency of different quenchers for phenol oxidation by permanganate with different molar of quencher : permanganate over wide pH range.
NADPH oxidase 2 plays a role in experimental corneal neovascularization
Authors: Chan Elsa C. , van Wijngaarden Peter , Chan Elsie , Ngo Darleen , Wang Jiang-Hui , Peshavariya Hitesh M. , Dusting Gregory J. , Liu Guei-Sheung
Published: January 2016

Corneal neovascularization, the growth of new blood vessels in the cornea, is a leading cause of vision impairment after corneal injury. Neovascularization typically occurs in response to corneal injury such as that caused by infection, physical trauma, chemical burns or in the setting of corneal transplant rejection. The NADPH oxidase enzyme complex is involved in cell signalling for wound-healing angiogenesis, but its role in corneal neovascularization has not been studied. We have now analysed the role of the Nox2 isoform of NADPH oxidase in corneal neovascularization in mice following chemical injury. C57BL/6 mice aged 8–14 weeks were cauterized with an applicator coated with 75% silver nitrate and 25% potassium nitrate for 8 s. Neovascularization extending radially from limbal vessels was observed in corneal whole-mounts from cauterized wild type mice and CD31+ vessels were identified in cauterized corneal sections at day 7. In contrast, in Nox2 knockout (Nox2 KO) mice vascular endothelial growth factor-A (Vegf-A), Flt1 mRNA expression, and the extent of corneal neovascularization were all markedly reduced compared with their wild type controls. The accumulation of Iba-1+ microglia and macrophages in the cornea was significantly less in Nox2 KO than in wild type mice. In conclusion, we have demonstrated that Nox2 is implicated in the inflammatory and neovascular response to corneal chemical injury in mice and clearly VEGF is a mediator of this effect. This work raises the possibility that therapies targeting Nox2 may have potential for suppressing corneal neovascularization and inflammation in humans.
Gender differences in developmental programming of cardiovascular diseases
Authors: Dasinger John Henry , Alexander Barbara T.
Published: January 2016

Hypertension is a risk factor for cardiovascular disease, the leading cause of death worldwide. Although multiple factors contribute to the pathogenesis of hypertension, studies by Dr David Barker reporting an inverse relationship between birth weight and blood pressure led to the hypothesis that slow growth during fetal life increased blood pressure and the risk for cardiovascular disease in later life. It is now recognized that growth during infancy and childhood, in addition to exposure to adverse influences during fetal life, contributes to the developmental programming of increased cardiovascular risk. Numerous epidemiological studies support the link between influences during early life and later cardiovascular health; experimental models provide proof of principle and indicate that numerous mechanisms contribute to the developmental origins of chronic disease. Sex has an impact on the severity of cardiovascular risk in experimental models of developmental insult. Yet, few studies examine the influence of sex on blood pressure and cardiovascular health in low-birth weight men and women. Fewer still assess the impact of ageing on sex differences in programmed cardiovascular risk. Thus, the aim of the present review is to highlight current data about sex differences in the developmental programming of blood pressure and cardiovascular disease.
Roadmap for the deployment of WAMPAC in the future GB power system
Authors: Cai Deyu , Wall Peter , Osborne Mark , Terzija Vladimir
Published: January 2016

This study presents a specific roadmap for the deployment of a wide area monitoring, protection, and control (WAMPAC) system in the future Great Britain (GB) power system. The specific roadmap is designed based on a generic roadmap, which draws on international experience with the development of WAMPAC systems, and a study of the changes in the GB power system. Based on this, the proposed specific roadmap identifies wide area oscillation monitoring as a key short term goal for the GB WAMPAC system and wide area oscillation control as a key long term goal for the GB WAMPAC system. To verify that this short term goal can be delivered simulations of a complete model of the GB power system that demonstrate that a new method based on a Newton Type algorithm will be more than capable of providing accurate oscillation monitoring in the GB WAMPAC system. Furthermore, for the same complete GB model it is demonstrated that the West coast CSC HVDC link can be used to create a powerful tool for oscillation damping that, with further research, should be capable of delivering the long‐term goal of wide area oscillation control as part of the specific GB WAMPAC roadmap.
Frequency‐domain harmonic matrix model for three‐phase diode‐bridge rectifier
Authors: Sun Yuanyuan , Dai Chuankai , Li Jiaqi , Yong Jing
Published: January 2016

Three‐phase diode‐bridge rectifier is a common front end for variable frequency drives/dc‐to‐dc converters, and is a well‐known harmonic source. The rectifier may operate in a dc current continuous or discontinuous mode, which creates a challenge in modelling the harmonic‐generation characteristics of such device. This study proposes a method to determine the operational modes of the rectifier under balanced operating conditions and then develops appropriate frequency‐domain harmonic models for each mode. The result is an integrated analytical harmonic matrix model for the three‐phase diode‐bridge rectifier. The matrix model can explicitly show the harmonic coupling effects between the rectifier ac supply voltages and its generated harmonic currents. Simulation and experiments have been done to verify the proposed model. The harmonic model has been applied to analyse the rectifier harmonic generating characteristics and the harmonic interactions between the rectifier and the grid.
Attraction of likely charged nano-sized grains in dust-electron plasmas
Authors: Vishnyakov Vladimir I.
Published: January 2016

Dust-electron plasma, which contains only the dust grains and electrons, emitted by them, is studied. Assumption of almost uniform spatial electrons distribution, which deviates from the uniformity only near the dust grains, leads to the grain charge division into two parts: first part is the individual for each grain “visible” charge and the second part is the common charge of the neutralized background. The visible grain charge can be both negative and positive, while the total grain charge is only positive. The attraction of likely charged grains is possible, because the grain interaction is determined by the visible charges. The equilibrium state between attraction and repulsion of grains is demonstrated.
Dynamic optimization methodology based on subgrid-scale dissipation for large eddy simulation
Authors: Yu Changping , Xiao Zuoli , Li Xinliang
Published: January 2016

A dynamic procedure based on subgrid-scale dissipation is proposed for large eddy simulation of turbulent flows. In the new method, the model coefficients are determined by minimizing the square error of the resolved dissipation rate based on the Germano identity. A dynamic two-term mixed model is tested and evaluated both a priori and a posteriori in simulations of homogeneous and isotropic turbulence. The new dynamic procedure proves to be more effective to optimize the model coefficients as compared with traditional method. The corresponding dynamic mixed model can predict the physical quantities more accurately than traditional dynamic mixed model.
Super-Maxwellian helium evaporation from pure and salty water
Authors: Hahn Christine , Kann Zachary R. , Faust Jennifer A. , Skinner J. L. , Nathanson Gilbert M.
Published: January 2016

Helium atoms evaporate from pure water and salty solutions in super-Maxwellian speed distributions, as observed experimentally and modeled theoretically. The experiments are performed by monitoring the velocities of dissolved He atoms that evaporate from microjets of pure water at 252 K and 4–8.5 molal LiCl and LiBr at 232–252 K. The average He atom energies exceed the flux-weighted Maxwell-Boltzmann average of 2RT by 30% for pure water and 70% for 8.5m LiBr. Classical molecular dynamics simulations closely reproduce the observed speed distributions and provide microscopic insight into the forces that eject the He atoms from solution. Comparisons of the density profile and He kinetic energies across the water-vacuum interface indicate that the He atoms are accelerated by He–water collisions within the top 1-2 layers of the liquid. We also find that the average He atom kinetic energy scales with the free energy of solvation of this sparingly soluble gas. This free-energy difference reflects the steeply decreasing potential of mean force on the He atoms in the interfacial region, whose gradient is the repulsive force that tends to expel the atoms. The accompanying sharp decrease in water density suppresses the He–water collisions that would otherwise maintain a Maxwell-Boltzmann distribution, allowing the He atom to escape at high energies. Helium is especially affected by this reduction in collisions because its weak interactions make energy transfer inefficient.
Molecular simulations and density functional theory calculations of bromine in clathrate hydrate phases
Authors: Dureckova Hana , Woo Tom K. , Alavi Saman
Published: January 2016

Bromine forms a tetragonal clathrate hydrate structure (TS-I) very rarely observed in clathrate hydrates of other guest substances. The detailed structure, energetics, and dynamics of Br2 and Cl2 in TS-I and cubic structure I (CS-I) clathrate hydrates are studied in this work using molecular dynamics and quantum chemical calculations. X-ray diffraction studies show that the halogen-water–oxygen distances in the cages of these structures are shorter than the sum of the van der Waals radii of halogen and oxygen atoms. This suggests that the stabilizing effects of halogen bonding or other non-covalent interactions (NCIs) may contribute to the formation of the unique tetragonal bromine hydrate structure. We performed molecular dynamics simulations of Br2 and Cl2 clathrate hydrates using our previously developed five-site charge models for the dihalogen molecules [Dureckova et al. Can. J. Chem. 93, 864 (2015)] which reproduce the computed electrostatic potentials of the dihalogens and account for the electropositive σ-hole of the halogen bond donor (the dihalogen). Analysis of the radial distribution functions, enthalpies of encapsulation, velocity and orientation autocorrelation functions, and polar angle distributions are carried out for Br2 and Cl2 guests in various cages to contrast the properties of these guests in the TS-I and CS-I phases. Quantum chemical partial geometry optimizations of Br2 and Cl2 guests in the hydrate cages using the M06-2X functional give short halogen-water distances compatible with values observed in X-ray diffraction experiments. NCI plots of guest-cage structures are generated to qualitatively show the relative strength of the non-bonding interactions between dihalogens and water molecules. The differences between behaviors of Br2 and Cl2 guests in the hydrate cages may explain why bromine forms the unique TS-I phase.
Multi-channel programmable power supply with temperature compensation for silicon sensors
Authors: Shukla R. A. , Achanta V. G. , Dugad S. R. , Freeman J. , Garde C. S. , Gupta S. K. , Khandekar P. D. , Kurup A. M. , Lokhandwala S. S. , Los S. , Prabhu S. S. , Rakshe P. S.
Published: January 2016

Silicon Photo-Multipliers (SiPMs) are increasingly becoming popular for discrete photon counting applications due to the wealth of advantages they offer over conventional photo-detectors such as photo-multiplier tubes and hybrid photo-diodes. SiPMs are used in variety of applications ranging from high energy physics and nuclear physics experiments to medical diagnostics. The gain of a SiPM is directly proportional to the difference between applied and breakdown voltage of the device. However, the breakdown voltage depends critically on the ambient temperature and has a large temperature co-efficient in the range of 40-60 mV/°C resulting in a typical gain variation of 3%-5%/°C [Dinu et al., in IEEE Nuclear Science Symposium, Medical Imaging Conference and 17th Room Temperature Semiconductor Detector Workshop (IEEE, 2010), p. 215]. We plan to use the SiPM as a replacement for PMT in the cosmic ray experiment (GRAPES-3) at Ooty [Gupta et al., Nucl. Instrum. Methods Phys. Res., Sect. A 540, 311 (2005)]. There the SiPMs will be operated in an outdoor environment subjected to temperature variation of about 15 °C over a day. A gain variation of more than 50% was observed for such large variations in the temperature. To stabilize the gain of the SiPM under such operating conditions, a low-cost, multi-channel programmable power supply (0-90 V) was designed that simultaneously provides the bias voltage to 16 SiPMs. The programmable power supply (PPS) was designed to automatically adjust the operating voltage for each channel with a built-in closed loop temperature feedback mechanism. The PPS provides bias voltage with a precision of 6 mV and measures the load current with a precision of 1 nA. Using this PPS, a gain stability of 0.5% for SiPM (Hamamatsu, S10931-050P) has been demonstrated over a wide temperature range of 15 °C. The design methodology of the PPS system, its validation, and the results of the tests carried out on the SiPM is presented in this article. The proposed design also has the capability of gain stabilization of devices with non-linear thermal response.
A tandem time–of–flight spectrometer for negative–ion/positive–ion coincidence measurements with soft x-ray excitation
Authors: Stråhlman Christian , Sankari Rami , Kivimäki Antti , Richter Robert , Coreno Marcello , Nyholm Ralf
Published: January 2016

We present a newly constructed spectrometer for negative–ion/positive–ion coincidence spectroscopy of gaseous samples. The instrument consists of two time–of–flight ion spectrometers and a magnetic momentum filter for deflection of electrons. The instrument can measure double and triple coincidences between mass–resolved negative and positive ions with high detection efficiency. First results include identification of several negative–ion/positive–ion coincidence channels following inner-shell photoexcitation of sulfur hexafluoride (SF6).
A self-consistent approach to the analysis of thermionic devices
Authors: Khoshaman Amir H. , Nojeh Alireza
Published: January 2016

Research in thermionics has been reinvigorated recently by the advent of nanotechnology and nanomaterials. Thermionic energy convertors are commonly modelled using the Poisson-Vlasov system of equations under various limitations and approximations. With the ever-growing demands of emergent thermionic devices, more comprehensive approaches are needed in order to be able to treat a broader range of device configurations and operational parameters. Here, we propose a self-consistent approach that, by iterating between the Poisson and Vlasov equations, does not rely on the existence of an analytical solution to the latter. Specifically, we present a particle-tracing implementation of this method for solving the system numerically in an efficient manner. In the case where an analytical solution does exist, we present an asymptotic expansion of the ill-behaving functions that arise; this approach improves the effectiveness of the method in the deep space-charge mode. We also demonstrate the applicability of this approach in the presence of back-emission.
All-epitaxial Co2FeSi/Ge/Co2FeSi trilayers fabricated by Sn-induced low-temperature epitaxy
Authors: Kawano M. , Ikawa M. , Arima K. , Yamada S. , Kanashima T. , Hamaya K.
Published: January 2016

We demonstrate low-temperature growth of all-epitaxial Co2FeSi/Ge/Co2FeSi trilayer structures by developing Sn-induced surfactant-mediated molecular beam epitaxy (SMBE) of Ge on Co2FeSi. Despite the growth of a semiconductor on a metal, we verify that the inserted Sn monolayers between Ge and Co2FeSi enable to promote the 2D epitaxial growth of Ge up to 5 nm at a TG of 250 °C. An understanding of the mechanism of the Sn-induced SMBE leads to the achievement of all-epitaxial Co2FeSi/Ge/Co2FeSi trilayer structures with spin-valve-like magnetization reversals. This study will open a way for vertical-type and high-performance Ge-based spintronics devices.
Mechanical and electronic properties of antiperovskite Ti-based compounds AXTi3 (X = C, N): A first-principles investigation
Authors: Wang Ni-Na , Shao Ding-Fu , Lu Wen-Jian , Lu Hong-Yan
Published: January 2016

In this paper, we systematically studied the mechanical and electronic properties of a series of antiperovskite-type Ti-based ternary carbides and nitrides AXTi3 (A = Ba, Ca, In, Sn, Sr, Zn, Cu, Al, Ga, Cd, and La; X = C, N) from first-principles calculations. By calculating the formation energies, elastic constants, and other mechanical parameters, we predicted that 7 carbides ACTi3 and 7 nitrides ANTi3 compounds are stable among the 22 compounds. The predicted large Young's modulus and high hardness imply a good mechanical application prospect of AXTi3. Particularly, SnNTi3 was found to show ferromagnetic ground state. For the electronic structure, our results confirm that the compounds are metallic in nature, and the density of states near the Fermi energy is predominately contributed by Ti-3d states. The effect of A- and X-site atom doping on AXTi3 can be evaluated by rigid band approximation. Our prediction will be useful for the experimental exploration of the new antiperovskite compounds.
Impurity and defect interactions during laser thermal annealing in Ge
Authors: Milazzo R. , Impellizzeri G. , Piccinotti D. , La Magna A. , Fortunato G. , De Salvador D. , Carnera A. , Portavoce A. , Mangelinck D. , Privitera V. , Napolitani E.
Published: January 2016

The microscopic mechanisms involving dopants, contaminants, and defects in Ge during pulsed melting laser thermal annealing (LTA) are investigated in detail. Samples both un-implanted and implanted with As or B are processed by LTA as well as characterized in terms of chemical (1D and 3D), electrical, and strain profiling. The clustering of As is directly measured by 3D chemical profiling and correlated with its partial electrical activation along with a reduction of the lattice strain induced by As atoms. A semi-quantitative microscopic model involving the interaction with mobile As-vacancy (AsV) complexes is proposed to describe the clustering mechanism. Boron is shown to follow different clustering behavior that changes with depth and marked by completely different strain levels. Oxygen penetrates from the surface into all the samples as a result of LTA and, only in un-implanted Ge, it occupies an interstitial position inducing also positive strain in the lattice. On the contrary, data suggest that the presence of As or B forces O to assume different configurations with negligible strain, through O-V or O-B interactions for the two dopant species, respectively. These data suggest that LTA does not inject a significant amount of vacancies in Ge, at variance with Si, unless As atoms or possibly other n-type dopants are present. These results have to be carefully considered for modeling the LTA process in Ge and its implementation in technology.
First-principles study of hydrogen-enhanced phosphorus diffusion in silicon
Authors: The Anh Le , Tien Cuong Nguyen , Lam Pham Tien , Manoharan Muruganathan , Mizuta Hiroshi , Matsumura Hideki , Otsuka Nobuo , Hieu Chi Dam
Published: January 2016

We present a first-principles study on the interstitial-mediated diffusion process of neutral phosphorus (P) atoms in a silicon crystal with the presence of mono-atomic hydrogen (H). By relaxing initial Si structures containing a P atom and an H atom, we derived four low-energy P-H-Si defect complexes whose formation energies are significantly lower than those of P-Si defect complexes. These four defect complexes are classified into two groups. In group A, an H atom is located near a Si atom, whereas in group B, an H atom is close to a P atom. We found that the H atom pairs with P or Si atom and changes the nature bonding between P and Si atoms from out-of-phase conjugation to in-phase conjugation. This fact results in the lower formation energies compare to the cases without H atom. For the migration of defect complexes, we have found that P-H-Si defect complexes can migrate with low barrier energies if an H atom sticks to either P or Si atom. Group B complexes can migrate from one lattice site to another with an H atom staying close to a P atom. Group A complexes cannot migrate from one lattice site to another without a transfer of an H atom from one Si atom to another Si atom. A change in the structure of defect complexes between groups A and B during the migration results in a transfer of an H atom between P and Si atoms. The results for diffusion of group B complexes show that the presence of mono-atomic H significantly reduces the activation energy of P diffusion in a Si crystal, which is considered as a summation of formation energy and migration barrier energy, leading to the enhancement of diffusion of P atoms at low temperatures, which has been suggested by recent experimental studies.
Multi-microscopy study of the influence of stacking faults and three-dimensional In distribution on the optical properties of m-plane InGaN quantum wells grown on microwire sidewalls
Authors: Mancini L. , Hernández-Maldonado D. , Lefebvre W. , Houard J. , Blum I. , Vurpillot F. , Eymery J. , Durand C. , Tchernycheva M. , Rigutti L.
Published: January 2016

The optical properties of m-plane InGaN/GaN quantum wells grown on microwire sidewalls were investigated carrying out a correlative scanning transmission electron microscopy (STEM), atom probe tomography (APT), and micro-photoluminescence study applied on single nanoscale field-emission tips obtained by a focused ion beam annular milling. Instead of assuming simple rectangular composition profiles, yielding misleading predictions for the optical transition energies, we can thus take into account actual compositional distributions and the presence of stacking faults (SFs). SFs were shown to be responsible for a lowering of the recombination energies of the order of 0.1 eV with respect to those expected for defect-free quantum wells (QWs). Such energy reduction allows establishing a good correspondence between the transition energies observed by optical spectroscopy and those calculated on the basis of the QWs In measured composition and distribution assessed by STEM structural analysis and APT chemical mapping.
Effect of high current electron beam in a 30 MeV radio frequency linac for neutron-time-of-flight applications
Authors: Nayak B. , Acharya S. , Rajawat R. K. , DasGupta K.
Published: January 2016

A high power pulsed radio frequency electron linac is designed by BARC, India to accelerate 30 MeV, 10 A, 10 ns beam for neutron-time-of-flight applications. It will be used as a neutron generator and will produce ∼1012–1013 n/s. It is essential to reduce the beam instability caused by space charge effect and the beam cavity interaction. In this paper, the wakefield losses in the accelerating section due to bunch of RMS (Root mean square) length 2 mm (at the gun exit) is analysed. Loss and kick factors are numerically calculated using CST wakefield solver. Both the longitudinal and transverse wake potentials are incorporated in beam dynamics code ELEGANT to find the transverse emittance growth of the beam propagating through the linac. Beam loading effect is examined by means of numerical computation carried out in ASTRA code. Beam break up start current has been estimated at the end of the linac which arises due to deflecting modes excited by the high current beam. At the end, transverse beam dynamics of such high current beam has been analysed.
Communication: A simplified coupled-cluster Lagrangian for polarizable embedding
Authors: Krause Katharina , Klopper Wim
Published: January 2016

A simplified coupled-cluster Lagrangian, which is linear in the Lagrangian multipliers, is proposed for the coupled-cluster treatment of a quantum mechanical system in a polarizable environment. In the simplified approach, the amplitude equations are decoupled from the Lagrangian multipliers and the energy obtained from the projected coupled-cluster equation corresponds to a stationary point of the Lagrangian.
Origins of enhanced thermoelectric power factor in topologically insulating Bi0.64Sb1.36Te3 thin films
Authors: Liu Wei , Chi Hang , Walrath J. C. , Chang A. S. , Stoica Vladimir A. , Endicott Lynn , Tang Xinfeng , Goldman R. S. , Uher Ctirad
Published: January 2016

In this research, we report the enhanced thermoelectric power factor in topologically insulating thin films of Bi0.64Sb1.36Te3 with a thickness of 6–200 nm. Measurements of scanning tunneling spectroscopy and electronic transport show that the Fermi level lies close to the valence band edge, and that the topological surface state (TSS) is electron dominated. We find that the Seebeck coefficient of the 6 nm and 15 nm thick films is dominated by the valence band, while the TSS chiefly contributes to the electrical conductivity. In contrast, the electronic transport of the reference 200 nm thick film behaves similar to bulk thermoelectric materials with low carrier concentration, implying the effect of the TSS on the electronic transport is merely prominent in the thin region. The conductivity of the 6 nm and 15 nm thick film is obviously higher than that in the 200 nm thick film owing to the highly mobile TSS conduction channel. As a consequence of the enhanced electrical conductivity and the suppressed bipolar effect in transport properties for the 6 nm thick film, an impressive power factor of about 2.0 mW m−1 K−2 is achieved at room temperature for this film. Further investigations of the electronic transport properties of TSS and interactions between TSS and the bulk band might result in a further improved thermoelectric power factor in topologically insulating Bi0.64Sb1.36Te3 thin films.
A physical model for the reverse leakage current in (In,Ga)N/GaN light-emitting diodes based on nanowires
Authors: Musolino M. , van Treeck D. , Tahraoui A. , Scarparo L. , De Santi C. , Meneghini M. , Zanoni E. , Geelhaar L. , Riechert H.
Published: January 2016

We investigated the origin of the high reverse leakage current in light emitting diodes (LEDs) based on (In,Ga)N/GaN nanowire (NW) ensembles grown by molecular beam epitaxy on Si substrates. To this end, capacitance deep level transient spectroscopy (DLTS) and temperature-dependent current-voltage (I-V) measurements were performed on a fully processed NW-LED. The DLTS measurements reveal the presence of two distinct electron traps with high concentrations in the depletion region of the p-i-n junction. These band gap states are located at energies of 570 ± 20 and 840 ± 30 meV below the conduction band minimum. The physical origin of these deep level states is discussed. The temperature-dependent I-V characteristics, acquired between 83 and 403 K, show that different conduction mechanisms cause the observed leakage current. On the basis of all these results, we developed a quantitative physical model for charge transport in the reverse bias regime. By taking into account the mutual interaction of variable range hopping and electron emission from Coulombic trap states, with the latter being described by phonon-assisted tunnelling and the Poole-Frenkel effect, we can model the experimental I-V curves in the entire range of temperatures with a consistent set of parameters. Our model should be applicable to planar GaN-based LEDs as well. Furthermore, possible approaches to decrease the leakage current in NW-LEDs are proposed.
Low-temperature characterization of Nb-Cu-Nb weak links with Ar ion-cleaned interfaces
Authors: Jabdaraghi R. N. , Peltonen J. T. , Saira O.-P. , Pekola J. P.
Published: January 2016

We characterize niobium-based lateral Superconductor (S)–Normal metal (N)–Superconductor (SNS) weak links through low-temperature switching current measurements and tunnel spectroscopy. We fabricate the SNS devices in two separate lithography and deposition steps, combined with strong argon ion cleaning before the normal metal deposition in the last step. Our SNS weak link consists of high-quality sputtered Nb electrodes that have contacted with evaporated Cu. The two-step fabrication flow enables more flexibility in the choice of materials and pattern design. A comparison of the temperature-dependent equilibrium critical supercurrent with theoretical predictions indicates that the quality of the Nb-Cu interface is similar to that of evaporated Al-Cu weak links. We further demonstrate a hybrid magnetic flux sensor based on an Nb-Cu-Nb SNS junction, where the phase-dependent normal metal density of states is probed with an Al tunnel junction.
A Concise Synthesis of Racemic Lorcaserin
Authors: Xu Bin , Su Jincai , Wang Jing , Zhou Guo-Chun
Published: January 2016

We report herein the concise synthesis of racemic lorcaserin (±)-1, which is an anti-obesity drug. The synthetic route involved the key synthesis of an asymmetrical imide intermediate 11 and its efficient reduction. Imide 11 was synthesized directly by the reaction of nitrile 9 with acid 10. The reducing system of NaBH4, AlCl3, and trimethylsilyl chloride efficiently fulfilled the reduction of imide 11 to amine 8a, which could be converted to (±)-1 via Friedel–Crafts reaction as reported. This route afforded 69 % two-step yield of 8a from 9 via 11, and the concise synthesis of (±)-1 was completed in three steps. This route offers an alternative pathway to the synthesis of (±)-1 and its analogues.
Determination of the free-ion concentration of rare earth elements by an ion-exchange technique: implementation, evaluation and limits
Authors: Leguay Sébastien , Campbell Peter G. C. , Fortin Claude
Published: January 2016

Environmental context
The lanthanides are a group of heavy elements (from lanthanum to lutetium) increasingly used in many electronic consumer products and little is known about their environmental mobility and toxicity. In natural systems, these elements will bind to natural organic matter but metal toxicity is usually defined by the free metal ion concentration. Here, we propose a method based on sample equilibration with an ion-exchange resin to measure the free lanthanide ion concentration in the presence of natural organic matter.

Abstract
An ion-exchange technique that employs a polystyrene sulphonate ion-exchange resin was developed for determining environmentally relevant free-ion concentrations of Ce, Eu, La and Nd. Owing to the high affinity of rare earth elements (REE) for the selected resin, this method requires the addition of an inert salt to increase the concentration of the counter-ions (i.e. cations that are exchanged with REE bound to the resin). The use of a batch equilibration approach to calibrate the resin allowed the implementation of the ion-exchange technique at reasonably low ionic strength (I = 0.1M). Several ligands were used to test the selectivity of the method, which proved to be highly selective for the free metal ion in presence of the tested cationic and anionic complexes (REE–nitrate, REE–malic acid and REE–nitrilotriacetic acid systems) and operational for very low proportions of REE3+, owing to the strong REE–resin interactions. The ion-exchange technique was also implemented to determine [Eu]inorg in the presence of natural humic matter (Suwannee River Humic Acid) and the results were compared with those obtained using equilibrium dialysis and those calculated with chemical equilibrium models. At pH 4.00, the measured [Eu]inorg values were in fairly good agreement with those predicted with the Windermere Humic Aqueous Model and Stockholm Humic Model, whereas the Non-Ideal Competitive Absorption model appeared to underestimate the [Eu]inorg. However, the inorganic europium concentrations were strongly underestimated (4 < [Eu]inorg, IET/[Eu]inorg, calc < 18) with the three prediction models at higher pH (5.3 and 6.2).
Greenhouse gas emissions from Brazil’s Amazonian hydroelectric dams
Authors: Fearnside Philip M
Published: January 2016

Tropical dams are often falsely portrayed as ‘clean’ emissions-free energy sources. The letter by de Faria et al (2015 Environ. Res. Lett.

10 124019) adds to evidence questioning this myth. Calculations are made for 18 dams that are planned or under construction in Brazilian Amazonia and show that emissions from storage hydroelectric dams would exceed those from electricity generation based on fossil fuels. Fossil fuels need not be the alternative, because Brazil has vast potential for wind and solar power as well as opportunities for energy conservation. Because dam-building is rapidly shifting to humid tropical areas, where emissions are higher than in other climatic zones, the impact of these emissions needs to be given proper weight in energy-policy decisions.
On digit frequencies in 𝛽-expansions
Authors: Boyland Philip , de Carvalho André , Hall Toby
Published: January 2016

We study the sets

DF
⁡
(
β
)

\operatorname {DF}(\beta )

of digit frequencies of

β
\beta

-expansions of numbers in 

[
0
,
1
]

[0,1]

. We show that

DF
⁡
(
β
)

\operatorname {DF}(\beta )

is a compact convex set with countably many extreme points which varies continuously with 

β
\beta

; that there is a full measure collection of non-trivial closed intervals on each of which

DF
⁡
(
β
)

\operatorname {DF}(\beta )

mode locks to a constant polytope with rational vertices; and that the generic digit frequency set has infinitely many extreme points, accumulating on a single non-rational extreme point whose components are rationally independent.
Mismatch Repair Protein Expression in Clear Cell Carcinoma of the Ovary
Authors: Bennett Jennifer A. , Morales-Oyarvide Vicente , Campbell Sharon , Longacre Teri A. , Oliva Esther
Published: January 2016

Several morphologic features have been reported to be predictive of abnormal expression of mismatch repair (MMR) proteins in endometrial and colon carcinomas. Although it is known that abnormal MMR expression is increased in frequency in ovarian endometrioid and clear cell carcinomas, no such histologic correlation has been identified. We reviewed 109 unselected ovarian clear cell carcinomas for specific tumor characteristics (architecture, nuclear atypia, signet ring cells, stromal hyalinization, background precursor) and inflammatory response (peritumoral lymphocytes found along the leading edge of the tumor, intratumoral stromal inflammation found within the tumor, percentage of plasma cells in the intratumoral stromal inflammation, tumor-infiltrating lymphocytes) and performed immunohistochemistry for all 4 MMR proteins. Abnormal MMR expression was identified in 6% of tumors and included MSH2/MSH6 (3), MLH1/PMS2 (1), MSH6 (1), and PMS2 (1). These patients had a mean age of 40 (range, 31 to 48) years, which contrasted with a mean of 53.2 (range, 28 to 82) years for the overall cohort. One had a concurrent diagnosis of endometrial carcinoma, whereas another had a family history of endometrial carcinoma. None had a personal/family history of colonic carcinoma. Tumors with diffuse intratumoral stromal inflammation and peritumoral lymphocytes were more frequently associated with MMR loss on univariate analysis (P<0.001 and 0.047, respectively) with diffuse intratumoral stromal inflammation remaining a significant independent predictor on multivariate analysis. None of the other morphologic features evaluated reached statistical significance. Although previous series have been unable to identify a relationship between histology and MMR expression, this study identified a correlation with diffuse intratumoral stromal inflammation and peritumoral lymphocytes, 2 features that potentially could be selected for MMR analysis if corroborated by other studies.
Rotating panoramic view: interaction between visual and olfactory cues in ants
Authors: Minoura Mai , Sonoda Kohei , Sakiyama Tomoko , Gunji Yukio-Pegio
Published: January 2016

Insects use a navigational toolkit consisting of multiple strategies such as path integration, view-dependent recognition methods and olfactory cues. The question arises as to how directional cues afforded by a visual panorama combine with olfactory cues from a pheromone trail to guide ants towards their nest. We positioned a garden antLasius nigeron a rotating table, whereon a segment of a pheromone trail relative to the stationary panorama was rotated while the ant walked along the trail towards its nest. The rotational speed of the table (3 r.p.m.) was set so that the table would rotate through about 90° by the time that an ant had walked from the start to the centre of the table. The ant completed a U-turn at about this point and so travelled in a nest-ward direction without leaving the trail. These results suggest that the ants persist on the pheromone trail and use visual input to determine their direction of travel along the trail.
On the equivalence between non-factorizable mixed-strategy classical games and quantum games
Authors: Iqbal Azhar , Chappell James M. , Abbott Derek
Published: January 2016

A game-theoretic setting provides a mathematical basis for analysis of strategic interaction among competing agents and provides insights into both classical and quantum decision theory and questions of strategic choice. An outstanding mathematical question is to understand the conditions under which a classical game-theoretic setting can be transformed to a quantum game, and under which conditions there is an equivalence. In this paper, we consider quantum games as those that allow non-factorizable probabilities. We discuss two approaches for obtaining a non-factorizable game and study the outcome of such games. We demonstrate how the standard version of a quantum game can be analysed as a non-factorizable game and determine the limitations of our approach.
Exploration adjustment by ant colonies
Authors: Doran Carolina , Stumpe Martin C. , Sendova-Franks Ana , Franks Nigel R.
Published: January 2016

How do animals in groups organize their work? Division of labour, i.e. the process by which individuals within a group choose which tasks to perform, has been extensively studied in social insects. Variability among individuals within a colony seems to underpin both the decision over which tasks to perform and the amount of effort to invest in a task. Studies have focused mainly on discrete tasks, i.e. tasks with a recognizable end. Here, we study the distribution of effort in nest seeking, in the absence of new nest sites. Hence, this task is open-ended and individuals have to decide when to stop searching, even though the task has not been completed. We show that collective search effort declines when colonies inhabit better homes, as a consequence of a reduction in the number of bouts (exploratory events). Furthermore, we show an increase in bout exploration time and a decrease in bout instantaneous speed for colonies inhabiting better homes. The effect of treatment on bout effort is very small; however, we suggest that the organization of work performed within nest searching is achieved both by a process of self-selection of the most hard-working ants and individual effort adjustment.
Using simulation to evaluate wildlife survey designs: polar bears and seals in the Chukchi Sea
Authors: Conn Paul B. , Moreland Erin E. , Regehr Eric V. , Richmond Erin L. , Cameron Michael F. , Boveng Peter L.
Published: January 2016

Logistically demanding and expensive wildlife surveys should ideally yield defensible estimates. Here, we show how simulation can be used to evaluate alternative survey designs for estimating wildlife abundance. Specifically, we evaluate the potential of instrument-based aerial surveys (combining infrared imagery with high-resolution digital photography to detect and identify species) for estimating abundance of polar bears and seals in the Chukchi Sea. We investigate the consequences of different levels of survey effort, flight track allocation and model configuration on bias and precision of abundance estimators. For bearded seals (0.07 animals km−2) and ringed seals (1.29 animals km−2), we find that eight flights traversing ≈7840 km are sufficient to achieve target precision levels (coefficient of variation (CV)<20%) for a 2.94×105 km2study area. For polar bears (provisionally, 0.003 animals km−2), 12 flights traversing ≈11 760 km resulted in CVs ranging from 28 to 35%. Estimators were relatively unbiased with similar precision over different flight track allocation strategies and estimation models, although some combinations had superior performance. These findings suggest that instrument-based aerial surveys may provide a viable means for monitoring seal and polar bear populations on the surface of the sea ice over large Arctic regions. More broadly, our simulation-based approach to evaluating survey designs can serve as a template for biologists designing their own surveys.
Rapid recovery following short-term acoustic disturbance in two fish species
Authors: Bruintjes Rick , Purser Julia , Everley Kirsty A. , Mangan Stephanie , Simpson Stephen D. , Radford Andrew N.
Published: January 2016

Noise from human activities is known to impact organisms in a variety of taxa, but most experimental studies on the behavioural effects of noise have focused on examining responses associated with the period of actual exposure. Unlike most pollutants, acoustic noise is generally short-lived, usually dissipating quickly after the source is turned off or leaves the area. In a series of experiments, we use established experimental paradigms to examine how fish behaviour and physiology are affected, both during short-term (2 min) exposure to playback of recordings of anthropogenic noise sources and in the immediate aftermath of noise exposure. We considered the anti-predator response and ventilation rate of juvenile European eels (
Anguilla anguilla
) and ventilation rate of juvenile European seabass (
Dicentrarchus labrax
). As previously found, additional-noise exposure decreased eel anti-predator responses, increased startle latency and increased ventilation rate relative to ambient-noise-exposed controls. Our results show for the first time that those effects quickly dissipated; eels showed rapid recovery of startle responses and startle latency, and rapid albeit incomplete recovery of ventilation rate in the 2 min after noise cessation. Seabass in both laboratory and open-water conditions showed an increased ventilation rate during playback of additional noise compared with ambient conditions. However, within 2 min of noise cessation, ventilation rate showed complete recovery to levels equivalent to ambient-exposed control individuals. Care should be taken in generalizing these rapid-recovery results, as individuals might have accrued other costs during noise exposure and other species might show different recovery times. Nonetheless, our results from two different fish species provide tentative cause for optimism with respect to recovery following short-duration noise exposure, and suggest that considering periods following noise exposures could be important for mitigation and management decisions.
The Achilles' heel hypothesis: misinformed keystone individuals impair collective learning and reduce group success
Authors: Pruitt Jonathan N. , Wright Colin M. , Keiser Carl N. , DeMarco Alex E. , Grobis Matthew M. , Pinter-Wollman Noa
Published: January 2016

Many animal societies rely on highly influential keystone individuals for proper functioning. When information quality is important for group success, such keystone individuals have the potential to diminish group performance if they possess inaccurate information. Here, we test whether information quality (accurate or inaccurate) influences collective outcomes when keystone individuals are the first to acquire it. We trained keystone or generic individuals to attack or avoid novel stimuli and implanted these trained individuals within groups of naive colony-mates. We subsequently tracked how quickly groups learned about their environment in situations that matched (accurate information) or mismatched (inaccurate information) the training of the trained individual. We found that colonies with just one accurately informed individual were quicker to learn to attack a novel prey stimulus than colonies with no informed individuals. However, this effect was no more pronounced when the informed individual was a keystone individual. In contrast, keystones with inaccurate information had larger effects than generic individuals with identical information: groups containing keystones with inaccurate information took longer to learn to attack/avoid prey/predator stimuli and gained less weight than groups harbouring generic individuals with identical information. Our results convey that misinformed keystone individuals can become points of vulnerability for their societies.