bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of surface-imprinted Ag nanoplates for detecting organic pollutants in water environments based on surface enhanced Raman scattering
Authors: Chen S. N. , Li X. , Han S. , Liu J. H. , Zhao Y. Y.
Published: November 2015

Ag-molecularly imprinted polymer (MIP) hybrid composites (Ag@MIPs) were prepared for the ultra-sensitive detection of organic pollutants in water based on surface enhanced Raman scattering (SERS).
Biphenyl as overcharge protection additive for nonaqueous sodium batteries
Authors: Feng Jinkui , Ci Lijie , Xiong Shenglin
Published: November 2015

Sodium batteries are considered as a promising low-cost alternative for currently used lithium batteries.
Redox reaction mediated direct synthesis of hierarchical flower-like CuO spheres anchored on electrospun poly(vinylidene difluoride) fiber surfaces at low temperatures
Authors: Lee Yun-Yang , Li Hsieh-Yu , Chiu Shih-Jiuan , Liang Wen-Li , Yeh Pi-Li , Liu Ying-Ling
Published: November 2015

Flower-like CuO spheres anchored on electrospun PVDF fiber surfaces as catalytic membranes for the photodegradation of rhodamine B aqueous solutions.
Changes in the SNAr reaction mechanism brought about by preferential solvation
Authors: Alarcón-Espósito Jazmín , Tapia Ricardo A. , Contreras Renato , Campodónico Paola R.
Published: November 2015

For model SNAr reactions in mixtures of acetonitrile and water, we found preferential solvation in favor of the aqueous phase.
Stacked Cu1.8S nanoplatelets as counter electrode for quantum dot-sensitized solar cell
Authors: Savariraj A. Dennyson , Rajendrakumar G. , Selvam Samayanan , Karthick S. N. , Balamuralitharan B. , Kim Hee-Je , Viswanathan Kodakkal Kannan , Vijayakumar M. , Prabakar Kandasamy
Published: November 2015

The electrocatalytic activity of Cu2−xS thin film QDSSC counter electrodes for reducing polysulfide electrolyte depends on surface active sulfide species and Cu deficiency.
Highly sensitive “turn-on” fluorescence probe for the detection of sparfloxacin in human serum using silica-functionalized CdTe quantum dots
Authors: Li Dan , Jia Shaojie , Fodjo Essy Kouadio , Xu Hu , Kong Cong , Wang Yuhong
Published: November 2015

The hydrophilic carboxyl-capped CdTe@SiO2 quantum dots (SQDs) can served as a “turn-on” photoluminescence (PL) probe for highly sensitive and selective detection of sparfloxacin in human serum.
Solution-processed organic light-emitting diodes with enhanced efficiency by using a non-conjugated polymer doped small-molecule hole-blocking layer
Authors: Tian Yuan , Peng Jinghong , Xu Xinjun , Li Lidong
Published: November 2015

A non-conjugated polymer has been doped into a small-molecule material to act as the hole-blocking layer in solution-processed OLEDs, resulting in an enhanced luminous efficiency and a reduced turn-on voltage.
Correction: One-shot carboxylation of microcrystalline cellulose in the presence of nitroxyl radicals and sodium periodate
Authors: Coseri Sergiu , Biliuta Gabriela , Zemljič Lidija Fras , Srndovic Jasna Stevanic , Larsson Per Tomas , Strnad Simona , Kreže Tatjana , Naderi Ali , Lindström Tom
Published: November 2015

Correction for ‘One-shot carboxylation of microcrystalline cellulose in the presence of nitroxyl radicals and sodium periodate’ by Sergiu Coseri et al., RSC Adv., 2015, 5, 85889–85897.
A novel quenched fluorescent activity-based probe reveals caspase-3 activity in the endoplasmic reticulum during apoptosis
Authors: Shaulov-Rotem Yulia , Merquiol Emmanuelle , Weiss-Sadan Tommy , Moshel Ofra , Salpeter Seth , Shabat Doron , Kaschani Farnusch , Kaiser Markus , Blum Galia
Published: November 2015

A selective quenched activity-based probe detects caspase-3 activity in the endoplasmic reticulum of cancerous cells during apoptosis.
Polymerized ionic liquid diblock copolymers: impact of water/ion clustering on ion conductivity
Authors: Nykaza Jacob R. , Ye Yuesheng , Nelson Rachel L. , Jackson Aaron C. , Beyer Frederick L. , Davis Eric M. , Page Kirt , Sharick Sharon , Winey Karen I. , Elabd Yossef A.
Published: November 2015

Herein, we examine the synergistic impact of both ion clustering and block copolymer morphology on ion conductivity in two polymerized ionic liquid (PIL) diblock copolymers with similar chemistries but different side alkyl spacer chain lengths (ethylversusundecyl).
Silica nanoparticles catalyse the formation of silica nanocapsules in a surfactant-free emulsion system
Authors: Zhao Yongliang , Chen Zhi , Zhu Xiaomin , Möller Martin
Published: November 2015

Interplay between methylated silica nanoparticles and polyethoxysiloxane at oil/water interface leads to a variety of silica capsule structures.
Construction of hierarchical ZnCo2O4@NixCo2x(OH)6x core/shell nanowire arrays for high-performance supercapacitors
Authors: Fu Wenbin , Wang Yaling , Han Weihua , Zhang Zemin , Zha Heming , Xie Erqing
Published: November 2015

Hierarchical ZnCo2O4@NixCo2x(OH)6x core/shell nanowire arrays have been successfully constructed for hybrid supercapacitors with outstanding performance.
pH-Triggered burst intracellular release from hollow microspheres to induce autophagic cancer cell death
Authors: Liang Xin , Yang Ying , Wang Lijun , Zhu Xianbing , Zeng Xiaowei , Wu Xiaojin , Chen Hongbo , Zhang Xudong , Mei Lin
Published: November 2015

Rapamycin–NaHCO3-loaded HMs combined CQ–NaHCO3-loaded HMs could efficiently induce cancer cell death through apoptosis with autophagosome both in vitro and in vivo.
Modifying a charge density wave transition by modulation doping: ferecrystalline compounds ([Sn1−xBixSe]1.15)1(VSe2)1 with 0 ≤ x ≤ 0.66
Authors: Falmbigl M. , Hay Z. , Ditto J. , Mitchson G. , Johnson D. C.
Published: November 2015

We report on the influence of modulation doping on the charge density wave transition in the ferecrystalline alloys ([Sn1−xBixSe]1.15)1(VSe2)1.
Method for sky region segmentation
Authors: Jiang Bo , Zhang Wan Xu , Ma Xiao Lei , Ru Yi , Meng Hong Qi , Wang Lin
Published: November 2015

A new simple and efficient method for sky region segmentation is proposed. The dark channel algorithm used in the field of image haze removal is further developed for sky region segmentation. The proposed method can simply and efficiently achieve image segmentation without any pretreatment which is required in traditional segmentation methods. This method is also conducive to detecting the distant fuzzy scene and suppressing the interference around the segmented object.
Low‐loss compact power combiner for solid state power amplifiers with high reliability
Authors: Gholami Mehrdad , Amaya Rony E. , Yagoub Mustapha C.E.
Published: November 2015

In this study, a low‐loss and compact planar power combiner for solid state power amplifiers (SSPAs) is proposed. It combines eight power amplifier modules with low insertion loss (IL) and high reliability by utilising a novel magic‐Tee configuration and E‐plane bend along with a suitable microstrip‐to‐waveguide transition. The fabricated prototype was implemented through automatic milling machines to produce three planar layers that form the final structure. This novel approach enabled precise fabrication, simple assembly of the SSPAs as well as low‐cost manufacturing in comparison with existing traditional approaches. This process is suitable for SSPAs operating from 4 to 40 GHz. The combined IL of the implemented combiner network is less than 0.6 dB at Ka‐band, 0.5 dB at Ku‐band, and 0.4 dB at X‐band while exhibiting a 10% fractional bandwidth.
Orthogonal frequency division multiplexing phenomenology: radar technique combining genetic algorithm‐based pulse design and energy detector for target recognition
Authors: Lellouch Gabriel , Mishra Amit Kumar , Inggs Michael
Published: November 2015

This study investigates the benefit offered by the orthogonal frequency division multiplexing (OFDM) structure to enhance the recognition functionality in OFDM radar. The authors propose a novel phenomenology‐based framework whereby the pulse is composed of several symbols each matched to a particular target and the recognition function in the receiver reduces to an energy detector. In this preliminary study, they make use of simple target models for which they have exact analytical expressions and apply genetic algorithm‐based methods to design the symbols. They emphasise on the need to work within a less undeterministic environment and demonstrate the merit of the authors’ technique with simulated results. Finally, they show how the integration of multiple echoes improves significantly the overall probability of correct classification despite additive white Gaussian noise.
Automated sample preparation for mercury analysis in wood materials
Authors: Vorberg Ellen , Fleischer Heidi , Junginger Steffen , Stoll Norbert , Thurow Kerstin
Published: November 2015

Laboratories that provide element‐specific measurements will gain on improved quality and better economical results by automating the required sample pre‐treatment. Commercially available, automated workstations are usually configured for handling the standardised multi‐titer‐plate‐format facilitating biological applications. In contrast, automating analytical processes, such as element‐specific applications, is still an unsolved challenge due to the required, specific process conditions. Therefore, the purpose of the presented work was the design and the realisation of an automated system providing precise sample pre‐treatment for element‐specific measurements. Finally, the developed system was successfully evaluated and ensures reliable sample pre‐treatment. The designed, flexible performance solution enables both system adaption and simultaneous sample handling. Moreover, the developed system allows for environmental investigations in a 24/7 manner. The results of the automated mercury analysis are in excellent agreement with the true value corresponding to a level of confidence of ∼95% (P = 95%) while using referenced and real wood materials.
Meshless analysis of bilayer graphene nanoribbon for radio frequency interconnects
Authors: Kanthamani S. , Gayathiri G. , Rohini S.
Published: November 2015

Numerical analysis of a bilayer graphene nanoribbon (BLGNR) using the reproducing kernel particle method (RKPM) – a true meshless approach – is reported. Electrostatic analysis of the BLGNR is performed using the RKPM approach. Validation of the structure is executed by comparing the result with an equivalent single conductor model and shows better accordance. Radio frequency (RF) analysis of the BLGNR as the interconnect is studied using advanced design systems with the quasi‐static analysis derived through the RKPM method. The simulation results in a return loss of −89.69 dB and transmission loss of −0.00028 dB at 1 THz which is suitable for RF interconnect applications.
Recent charge-breeding developments with EBIS/T devices (invited)
Authors: Schwarz S. , Lapierre A.
Published: November 2015

Short breeding times, narrow charge state distributions, low background, high efficiency, and the flexible time structure of the ejected low-emittance ion pulses are among the most attractive features of electron beam ion source or trap (EBIS/T) based charge breeders. Significant progress has been made to further improve these properties: Several groups are working to increase current densities towards 103 or even 104 A/cm2. These current densities will become necessary to deliver high charge states of heavy nuclei in a short time and/or provide sufficient space-charge capacity to handle high-current ion beams in next-generation rare-isotope beam (RIB) facilities. Efficient capture of continuous beams, attractive because of its potential of handling highest-current ion beams, has become possible with the development of high-density electron beams of >1 A. Requests for the time structure of the charge bred ion pulse range from ultra-short pulses to quasi-continuous beams. Progress is being made on both ends of this spectrum, by either dividing the extracted charge in many pulse-lets, adjusting the extraction potential for a near-uniform long pulse, or adding dedicated devices to spread the ion bunches delivered from the EBIS/T in time. Advances in EBIS/T charge state breeding are summarized, including recent results with NSCL’s ReA EBIS/T charge breeder.
Crossover between activated reptation and arm retraction mechanisms in entangled rod-coil block copolymers
Authors: Wang Muzhou , Likhtman Alexei E. , Olsen Bradley D.
Published: November 2015

Using a coarse-grained slip-spring model, the dynamics of rod-coil block copolymers is explored over a wide parameter space to fully capture the crossover between the short rod (activated reptation) and long rod (arm retraction) limits. An analytical, closed-form expression for curvilinear diffusion by activated reptation was derived by separating the drag into individual components for the rod and coil block. Curvilinear diffusion in the intermediate rod regime, where both mechanisms are important, was then found to be faster than predicted when both mechanisms are independently combined. The discrepancy in the crossover regime arises because the rod-coil copolymer’s exploration of space is not accurately described by either a coil homopolymer (assumed by activated reptation) or a rod homopolymer (assumed by arm retraction). This effect is explored by tracking the rod orientation as the polymer reptates, confirming that the polymer reptates along a path that becomes more rodlike as the rod fraction is increased. Thus, activated reptation under-predicts diffusion because the rod can choose reptation paths that are more extended than the coil homopolymer by renewal of the entanglement tube from the ends. Arm retraction under-predicts diffusion because minor rotations of the rod allow some motion before full retractions of the coil block. Finally, more familiar 3-dimensional center-of-mass diffusion measurements are related to the curvilinear diffusion analysis because the ratio of these two quantities varies smoothly between the coil and rod homopolymer limits as the reptation path becomes more extended.
Ion source research and development at University of Jyväskylä: Studies of different plasma processes and towards the higher beam intensities
Authors: Koivisto H. , Kalvas T. , Tarvainen O. , Komppula J. , Laulainen J. , Kronholm R. , Ranttila K. , Tuunanen J. , Thuillier T. , Xie D. , Machicoane G.
Published: November 2015

Several ion source related research and development projects are in progress at the Department of Physics, University of Jyväskylä (JYFL). The work can be divided into investigation of the ion source plasma and development of ion sources, ion beams, and diagnostics. The investigation covers the Electron Cyclotron Resonance Ion Source (ECRIS) plasma instabilities, vacuum ultraviolet (VUV) and visible light emission, photon induced electron emission, and the development of plasma diagnostics. The ion source development covers the work performed for radiofrequency-driven negative ion source, RADIS, beam line upgrade of the JYFL 14 GHz ECRIS, and the development of a new room-temperature-magnet 18 GHz ECRIS, HIISI.
Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids
Authors: Jablonowski H. , Bussiahn R. , Hammer M. U. , Weltmann K.-D. , von Woedtke Th. , Reuter S.
Published: November 2015

Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100–400 nm) and, in particular, vacuum ultraviolet (VUV, 10–200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH2O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H2O2) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O2•−) and hydroxyl radicals (•OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.
A broadband gyrotron backward-wave oscillator with tapered interaction structure and magnetic field
Authors: Li G. D. , Chang P. C. , Chen H. Y. , Chiang W. Y. , Fan C. T. , Lin P. N. , Kao S. H. , Lin Y. N. , Huang Y. J. , Barnett L. R. , Chu K. R.
Published: November 2015

The gyro-monotron and gyrotron backward-wave oscillator (gyro-BWO) are the two oscillator versions of gyrotrons. While serving different functions, they are also radically different in the RF field formation mechanisms. The gyro-monotron RF field profile is essentially fixed by the resonant interaction structure, while the gyro-BWO possesses an extra degree of freedom in that the axial RF field profile is self-determined by the beam-wave interaction in a waveguide structure. The present study examines ways to utilize the latter feature for bandwidth broadening with a tapered magnetic field, while also employing a tapered waveguide to enhance the interaction efficiency. We begin with a mode competition analysis, which suggests the theoretical feasibility of broadband frequency tuning in single-mode operation. It is then shown in theory that, by controlling the RF field profile with an up- or down-tapered magnetic field, the gyro-BWO is capable of efficient operation with a much improved tunable bandwidth.
Origin of the Hadži ABC structure: An ab initio study
Authors: Van Hoozen Brian L. , Petersen Poul B.
Published: November 2015

Medium and strong hydrogen bonds are well known to give rise to broad features in the vibrational spectrum often spanning several hundred wavenumbers. In some cases, these features can span over 1000 cm−1 and even contain multiple broad peaks. One class of strongly hydrogen-bonded dimers that includes many different phosphinic, phosphoric, sulfinic, and selenic acid homodimers exhibits a three-peaked structure over 1500 cm−1 broad. This unusual feature is often referred to as the Hadži ABC structure. The origin of this feature has been debated since its discovery in the 1950s. Only a couple of theoretical studies have attempted to interpret the origin of this feature; however, no previous study has been able to reproduce this feature from first principles. Here, we present the first ab initio calculation of the Hadži ABC structure. Using a reduced dimensionality calculation that includes four vibrational modes, we are able to reproduce the three-peak structure and much of the broadness of the feature. Our results indicate that Fermi resonances of the in-plane bend, out-of-plane bend, and combination of these bends play significant roles in explaining this feature. Much of the broadness of the feature and the ability of the OH stretch mode to couple with many overtone bending modes are captured by including an adiabatically separated dimer stretch mode in the model. This mode modulates the distance between the monomer units and accordingly the strength of the hydrogen-bonds causing the OH stretch frequency to shift from 2000 to 3000 cm−1. Using this model, we were also able to reproduce the vibrational spectrum of the deuterated isotopologue which consists of a single 500 cm−1 broad feature. Whereas previous empirical studies have asserted that Fermi resonances contribute very little to this feature, our study indicates that while not appearing as a separate peak, a Fermi resonance of the in-plane bend contributes substantially to the feature.
Photoelectron spectroscopy of hexachloroplatinate-nucleobase complexes: Nucleobase excited state decay observed via delayed electron emission
Authors: Sen Ananya , Matthews Edward M. , Hou Gao-Lei , Wang Xue-Bin , Dessent Caroline E. H.
Published: November 2015

We report low-temperature photoelectron spectra of isolated gas-phase complexes of the hexachloroplatinate dianion bound to the nucleobases uracil, thymine, cytosine, and adenine. The spectra display well-resolved, distinct peaks that are consistent with complexes where the hexachloroplatinate dianion is largely intact. Adiabatic electron detachment energies for the hexachloroplatinate-nucleobase complexes are measured as 2.26-2.36 eV. The magnitudes of the repulsive Coulomb barriers (RCBs) of the complexes are all ∼1.7 eV, values that are lower than the RCB of the uncomplexed PtCl62− dianion as a result of charge solvation by the nucleobases. In addition to the resolved spectral features, broad featureless bands indicative of delayed electron detachment are observed in the 193 nm photoelectron spectra of the four clusters. The 266 nm spectra of the PtCl62− ⋅ thymine and PtCl62− ⋅ adenine complexes also display very prominent delayed electron emission bands. These results mirror recent results on the related Pt(CN)42− ⋅ nucleobase complexes [A. Sen et al., J. Phys. Chem. B 119, 11626 (2015)]. The observation of delayed electron emission bands in the PtCl62− ⋅ nucleobase spectra obtained in this work, as for the previously studied Pt(CN)42− ⋅ nucleobase complexes, is attributed to one-photon excitation of nucleobase-centred excited states that can effectively couple to the electron detachment continuum, producing strong electron detachment. Moreover, the selective, strong excitation of the delayed emission bands in the 266 nm spectra is linked to fundamental differences in the individual nucleobase photophysics at this excitation energy. This strongly supports our previous suggestion that the dianion within these clusters can be viewed as a “dynamic tag” which has the propensity to emit electrons when the attached nucleobase decays over a time scale long enough to allow autodetachment.
A high-overtone bulk acoustic wave resonator-oscillator-based 4.596 GHz frequency source: Application to a coherent population trapping Cs vapor cell atomic clock
Authors: Daugey Thomas , Friedt Jean-Michel , Martin Gilles , Boudot Rodolphe
Published: November 2015

This article reports on the design and characterization of a high-overtone bulk acoustic wave resonator (HBAR)-oscillator-based 4.596 GHz frequency source. A 2.298 GHz signal, generated by an oscillator constructed around a thermally controlled two-port aluminum nitride-sapphire HBAR resonator with a Q-factor of 24 000 at 68 °C, is frequency multiplied by 2–4.596 GHz, half of the Cs atom clock frequency. The temperature coefficient of frequency of the HBAR is measured to be −23 ppm/ °C at 2.298 GHz. The measured phase noise of the 4.596 GHz source is −105 dB rad2/Hz at 1 kHz offset and −150 dB rad2/Hz at 100 kHz offset. The 4.596 GHz output signal is used as a local oscillator in a laboratory-prototype Cs microcell-based coherent population trapping atomic clock. The signal is stabilized onto the atomic transition frequency by tuning finely a voltage-controlled phase shifter implemented in the 2.298 GHz HBAR-oscillator loop, preventing the need for a high-power-consuming direct digital synthesis. The short-term fractional frequency stability of the free-running oscillator is 1.8 × 10−9 at one second integration time. In locked regime, the latter is improved in a preliminary proof-of-concept experiment at the level of 6.6 × 10−11 τ−1/2 up to a few seconds and found to be limited by the signal-to-noise ratio of the detected CPT resonance.
Nonparametric variational optimization of reaction coordinates
Authors: Banushkina Polina V. , Krivov Sergei V.
Published: November 2015

State of the art realistic simulations of complex atomic processes commonly produce trajectories of large size, making the development of automated analysis tools very important. A popular approach aimed at extracting dynamical information consists of projecting these trajectories into optimally selected reaction coordinates or collective variables. For equilibrium dynamics between any two boundary states, the committor function also known as the folding probability in protein folding studies is often considered as the optimal coordinate. To determine it, one selects a functional form with many parameters and trains it on the trajectories using various criteria. A major problem with such an approach is that a poor initial choice of the functional form may lead to sub-optimal results. Here, we describe an approach which allows one to optimize the reaction coordinate without selecting its functional form and thus avoiding this source of error.
High fidelity modeling of thermal relaxation and dissociation of oxygen
Authors: Andrienko Daniil A. , Boyd Iain D.
Published: November 2015

A master equation study of vibrational relaxation and dissociation of oxygen is conducted using state-specific O2–O transition rates, generated by extensive trajectory simulations. Both O2–O and O2–O2 collisions are concurrently simulated in the evolving nonequilibrium gas system under constant heat bath conditions. The forced harmonic oscillator model is incorporated to simulate the state-to-state relaxation of oxygen in O2–O2 collisions. The system of master equations is solved to simulate heating and cooling flows. The present study demonstrates the importance of atom-diatom collisions due to the extremely efficient energy randomization in the intermediate O3 complex. It is shown that the presence of atomic oxygen has a significant impact on vibrational relaxation time at temperatures observed in hypersonic flow. The population of highly-excited O2 vibrational states is affected by the amount of atomic oxygen when modeling the relaxation under constant heat bath conditions. A model of coupled state-to-state vibrational relaxation and dissociation of oxygen is also discussed.
Scattering of NH3 and ND3 with rare gas atoms at low collision energy
Authors: Loreau J. , van der Avoird A.
Published: November 2015

We present a theoretical study of elastic and rotationally inelastic collisions of NH3 and ND3 with rare gas atoms (He, Ne, Ar, Kr, Xe) at low energy. Quantum close-coupling calculations have been performed for energies between 0.001 and 300 cm−1. We focus on collisions in which NH3 is initially in the upper state of the inversion doublet with j = 1, k = 1, which is the most relevant in an experimental context as it can be trapped electrostatically and Stark-decelerated. We discuss the presence of resonances in the elastic and inelastic cross sections, as well as the trends in the inelastic cross sections along the rare gas series and the differences between NH3 and ND3 as a colliding partner. We also demonstrate the importance of explicitly taking into account the umbrella (inversion) motion of NH3 in order to obtain accurate scattering cross sections at low collision energy. Finally, we investigate the possibility of sympathetic cooling of ammonia using cold or ultracold rare gas atoms. We show that some systems exhibit a large ratio of elastic to inelastic cross sections in the cold regime, which is promising for sympathetic cooling experiments. The close-coupling calculations are based on previously reported ab initio potential energy surfaces for NH3–He and NH3–Ar, as well as on new, four-dimensional, potential energy surfaces for the interaction of ammonia with Ne, Kr, and Xe, which were computed using the coupled-cluster method and large basis sets. We compare the properties of the potential energy surfaces corresponding to the interaction of ammonia with the various rare gas atoms.
Metallic nanoparticles meet metadynamics
Authors: Pavan L. , Rossi K. , Baletto F.
Published: November 2015

Metadynamics coupled with classical molecular dynamics has been successfully applied to sample the configuration space of metallic and bimetallic nanoclusters. We implement a new set of collective variables related to the pair distance distribution function of the nanoparticle to achieve an exhaustive isomer sampling. As paradigmatic examples, we apply our methodology to Ag147, Pt147, and their alloy AgshellPtcore at 2:1 and 1:1 chemical compositions. The proposed scheme is able to reproduce the known solid-solid structural transformation pathways, based on the Lipscomb’s diamond-square-diamond mechanisms, both in mono and bimetallic nanoparticles. A discussion of the free energy barriers involved in these processes is provided.
Traveling interface modulations and anisotropic front propagation in ammonia oxidation over Rh(110)
Authors: Rafti Matías , Borkenhagen Benjamin , Lilienkamp Gerhard , Lovis Florian , Smolinsky Tim , Imbihl Ronald
Published: November 2015

The bistable NH3 + O2 reaction over a Rh(110) surface was explored in the pressure range 10−6–10−3 mbar and in the temperature range 300–900 K using photoemission electron microscopy and low energy electron microscopy as spatially resolving methods. We observed a history dependent anisotropy in front propagation, traveling interface modulations, transitions with secondary reaction fronts, and stationary island structures.
A study on the steady-state solutions of a Bursian diode in the presence of transverse magnetic field, when the electrons of the injected beam are turned back partially or totally
Authors: Pramanik Sourav , Kuznetsov V. I. , Chakrabarti Nikhil
Published: November 2015

The properties of a steady-state planar vacuum diode driven by a cold electron beam have been investigated in the presence of an external transverse magnetic field, employing both the Eulerian and the Lagrangian formalism. With the help of a numerical scheme, the features of the steady-state solutions have been explored in the Eulerian frame, particularly for the case that corresponds to the potential distributions with a virtual cathode. However, exact analytical formulae for the potential and velocity profiles within the inter-electrode region have been derived with the Lagrangian description. In contrast to the previous work [Phys. Plasmas 22, 042110 (2015)], here we have emphasized the situation when electrons are reflected back to the emitter by the magnetic field. Both partial and complete reflection of the electrons due to the magnetic field have been taken into account. Using the emitter electric field as a characteristic parameter, steady-state solutions have been evaluated for specific values of diode length, applied voltage, and magnetic field strength. It has been shown that, due to the inclusion of the magnetic field, a new region of non-unique solutions appears. An external magnetic field seems to have a profound effect in controlling fast electronic switches based on the Bursian diode.
The influence of temperature and grain boundary volume on the resistivity of nanocrystalline nickel
Authors: Darnbrough J. E. , Roebuck B. , Flewitt P. E. J.
Published: November 2015

The thermal stability and modes of recrystallisation of nanocrystalline nickel has been observed through a conduction-based non-destructive test. Resistivity measurements have been utilised to quantify grain boundary volume fraction and microstructure. This observation makes clear the distinction of the factors that contribute to resistivity and demonstrates that these contributions are related to microstructure, either directly or in-directly. In static systems, the contribution of ordered grains and low-order grain boundary atomic arrangements in small grained material has been measured and correlated with resistivity. Measurements of in-situ resistivity conducted at high temperature gives changes with time which are related to grain growth, during heat treatment. This shows that resistivity can be used as a technique for observing the microstructure and grain growth of small grained material.
Output power of a quantum dot laser: Effects of excited states
Authors: Wu Yuchang , Jiang Li , Asryan Levon V.
Published: November 2015

A theory of operating characteristics of quantum dot (QD) lasers is discussed in the presence of excited states in QDs. We consider three possible situations for lasing: (i) ground-state lasing only; (ii) ground-state lasing at first and then the onset of also excited-state lasing with increasing injection current; (iii) excited-state lasing only. The following characteristics are studied: occupancies of the ground-state and excited-state in QDs, free carrier density in the optical confinement layer, threshold currents for ground- and excited-state lasing, densities of photons emitted via ground- and excited-state stimulated transitions, output power, internal and external differential quantum efficiencies. Under the conditions of ground-state lasing only, the output power saturates with injection current. Under the conditions of both ground- and excited-state lasing, the output power of ground-state lasing remains pinned above the excited-state lasing threshold while the power of excited-state lasing increases. There is a kink in the light-current curve at the excited-state lasing threshold. The case of excited-state lasing only is qualitatively similar to that for single-state QDs—the role of ground-state transitions is simply reduced to increasing the threshold current.
Eigenvalues of the Neumann Laplacian in symmetric regions
Authors: Marrocos Marcus A. M. , Pereira Antônio L.
Published: November 2015

In this work, we are concerned with the multiplicity of the eigenvalues of the Neumann Laplacian in regions of ℝn which are invariant under the natural action of a compact subgroup G of O(n). We give a partial positive answer (in the Neumann case) to a conjecture of Arnol’d [Funct. Anal. Appl. 6, 94-101 (1972)] on the transversality of the transformation given by the Dirichlet integral to the stratification in the space of quadratic forms according to the multiplicities of the eigenvalues. We show, for some classes of subgroups of O(n) that, generically in the set of G − invariant, C2-regions, the action is irreducible in each eigenspace Ker(Δ + λ). These classes include finite subgroups with irreducible representations of dimension not greater than 2 and, in the case n = 2, any compact subgroup of O(2). We also obtain some partial results for general compact subgroups of O(n).
Time differentiated nuclear resonance spectroscopy coupled with pulsed laser heating in diamond anvil cells
Authors: Kupenko I. , Strohm C. , McCammon C. , Cerantola V. , Glazyrin K. , Petitgirard S. , Vasiukov D. , Aprilis G. , Chumakov A. I. , Rüffer R. , Dubrovinsky L.
Published: November 2015

Developments in pulsed laser heating applied to nuclear resonance techniques are presented together with their applications to studies of geophysically relevant materials. Continuous laser heating in diamond anvil cells is a widely used method to generate extreme temperatures at static high pressure conditions in order to study the structure and properties of materials found in deep planetary interiors. The pulsed laser heating technique has advantages over continuous heating, including prevention of the spreading of heated sample and/or the pressure medium and, thus, a better stability of the heating process. Time differentiated data acquisition coupled with pulsed laser heating in diamond anvil cells was successfully tested at the Nuclear Resonance beamline (ID18) of the European Synchrotron Radiation Facility. We show examples applying the method to investigation of an assemblage containing ε-Fe, FeO, and Fe3C using synchrotron Mössbauer source spectroscopy, FeCO3 using nuclear inelastic scattering, and Fe2O3 using nuclear forward scattering. These examples demonstrate the applicability of pulsed laser heating in diamond anvil cells to spectroscopic techniques with long data acquisition times, because it enables stable pulsed heating with data collection at specific time intervals that are synchronized with laser pulses.
Reducing wall plasma expansion with gold foam irradiated by laser
Authors: Zhang Lu , Ding Yongkun , Jiang Shaoen , Yang Jiamin , Li Hang , Kuang Longyu , Lin Zhiwei , Jing Longfei , Li Liling , Deng Bo , Yuan Zheng , Chen Tao , Yuan Guanghui , Tan Xiulan , Li Ping
Published: November 2015

The experimental study on the expanding plasma movement of low-density gold foam (∼1% solid density) irradiated by a high power laser is reported in this paper. Experiments were conducted using the SG-III prototype laser. Compared to solid gold with 19.3 g/cc density, the velocities of X-ray emission fronts moving off the wall are much smaller for gold foam with 0.3 g/cc density. Theoretical analysis and MULTI 1D simulation results also show less plasma blow-off, and that the density contour movement velocities of gold foam are smaller than those of solid gold, agreeing with experimental results. These results indicate that foam walls have advantages in symmetry control and lowering plasma fill when used in ignition hohlraum.
Unfolding of globular polymers by external force
Authors: Bell Samuel , Terentjev Eugene M.
Published: November 2015

We examine the problem of a polymer chain, folded into a globule in poor solvent, subjected to a constant tensile force. Such a situation represents a Gibbs thermodynamic ensemble and is useful for analysing force-clamp atomic force microscopy measurements, now very common in molecular biophysics. Using a basic Flory mean-field theory, we account for surface interactions of monomers with solvent. Under an increasing tensile force, a first-order phase transition occurs from a compact globule to a fully extended chain, in an “all-or-nothing” unfolding event. This contrasts with the regime of imposed extension, first studied by Halperin and Zhulina [Europhys. Lett. 15, 417 (1991)], where there is a regime of coexistence of a partial globule with an extended chain segment. We relate the transition forces in this problem to the solvent quality and degree of polymerisation, and also find analytical expressions for the energy barriers present in the problem. Using these expressions, we analyse the kinetic problem of a force-ramp experiment and show that the force at which a globule ruptures depends on the rate of loading.
Numerical study of the generation of runaway electrons in a gas diode with a hot channel
Authors: Lisenkov V. V. , Shklyaev V. A.
Published: November 2015

A new method for increasing the efficiency of runaway electron beam generation in atmospheric pressure gas media has been suggested and theoretically proved. The method consists of creating a hot region (e.g., a spark channel or a laser plume) with a decreased numerical density of gas molecules (N) near the cathode. In this method, the ratio E/N (E—electric field strength) is increased by decreasing N instead of increasing E, as has been done in the past. The numerical model that is used allows the simultaneous calculation of the formation of a subnanosecond gas discharge and the generation of runaway electrons in gas media. The calculations have demonstrated the possibility of obtaining current pulses of runaway electrons with amplitudes of hundred of amperes and durations of more than 100 ps. The influence of the hot channel geometry on the parameters of the generated beam has been investigated.
Kinetic model of force-free current sheets with non-uniform temperature
Authors: Kolotkov D. Y. , Vasko I. Y. , Nakariakov V. M.
Published: November 2015

The kinetic model of a one-dimensional force-free current sheet (CS) developed recently by Harrison and Neukirch [Phys. Rev. Lett. 102(13), 135003 (2009)] predicts uniform distributions of the plasma temperature and density across the CS. However, in realistic physical systems, inhomogeneities of these plasma parameters may arise quite naturally due to the boundary conditions or local plasma heating. Moreover, as the CS spatial scale becomes larger than the characteristic kinetic scales (the regime often referred to as the MHD limit), it should be possible to set arbitrary density and temperature profiles. Thus, an advanced model has to allow for inhomogeneities of the macroscopic plasma parameters across the CS, to be consistent with the MHD limit. In this paper, we generalise the kinetic model of a force-free current sheet, taking into account the inhomogeneity of the density and temperature across the CS. In the developed model, the density may either be enhanced or depleted in the CS central region. The temperature profile is prescribed by the density profile, keeping the plasma pressure uniform across the CS. All macroscopic parameters, as well as the distribution functions for the protons and electrons, are determined analytically. Applications of the developed model to current sheets observed in space plasmas are discussed.
Hom-Hopf group coalgebras and braided T-categories obtained from Hom-Hopf algebras
Authors: You Miman , Zhou Nan , Wang Shuanhong
Published: November 2015

The main aim of this paper is to provide new examples of braided T-categories in the sense of Turaev [Arabian J. Sci. Eng., Sect. C 33(2C), 483–503 (2008)]. For this purpose, we first introduce a class of new twisted Yetter-Drinfeld modules categories. Then, we construct a new braided T-category, generalizing the main constructions by Panaite and Staic [Isr. J. Math. 158, 349–366 (2007)]. Finally, we show that the new braided T-category in some conditions coincides with the representations of a certain Hom-Hopf group-coalgebra that we construct.
Resonant photoemission spectroscopy for intermediate band materials
Authors: Mazzola F. , Nematollahi M. , Li Z. S. , Cooil S. , Yang X. , Reenaas T. W. , Wells J. W.
Published: November 2015

Resonant photoemission spectroscopy is used to study the intermediate-band material Cr doped ZnS. Using resonant photoemission, we show that the intermediate-band can be characterized, revealing the filling and specific orbital character of the states contributing to the resonant photoemission signal. We demonstrate that resonant photoemission spectroscopy is a powerful approach for understanding the origin of intermediate bands in doped ZnS. The methodology can be widely extended to a large variety of materials, providing useful information towards engineering of high efficiency intermediate band solar cells and of other optoelectronic devices.
Rectangular split-ring resonators with single-split and two-splits under different excitations at microwave frequencies
Authors: Zahertar S. , Yalcinkaya A. D. , Torun H.
Published: November 2015

In this work, transmission characteristics of rectangular split-ring resonators with single-split and two-splits are analyzed at microwave frequencies. The resonators are coupled with monopole antennas for excitation. The scattering parameters of the devices are investigated under different polarizations of E and H fields. The magnetic resonances induced by E and H fields are identified and the differences in the behavior of the resonators due to orientations of the fields are explained based on simulation and experimental results. The addition of the second split of the device is investigated considering different configurations of the excitation vectors. It is demonstrated that the single-split and the two-splits resonators exhibit identical transmission characteristics for a certain excitation configuration as verified with simulations and experiments. The presented resonators can effectively function as frequency selective media for varying excitation conditions.
Measuring the complex field scattered by single submicron particles
Authors: Potenza Marco A. C. , Sanvito Tiziano , Pullia Alberto
Published: November 2015

We describe a method for simultaneous measurements of the real and imaginary parts of the field scattered by single nanoparticles illuminated by a laser beam, exploiting a self-reference interferometric scheme relying on the fundamentals of the Optical Theorem. Results obtained with calibrated spheres of different materials are compared to the expected values obtained through a simplified analytical model without any free parameters, and the method is applied to a highly polydisperse water suspension of Poly(D,L-lactide-co-glycolide) nanoparticles. Advantages with respect to existing methods and possible applications are discussed.
Natural history and display behaviour of Servaea incana, a common and widespread Australian jumping spider (Araneae : Salticidae)
Authors: McGinley Rowan H. , Mendez Vivian , Taylor Phillip W.
Published: November 2015

The natural history and intraspecific interactions of Servaea incana, a common jumping spider of temperate Australia, are described. S. incana inhabits the trunks of eucalypt trees, where it builds silken retreats and nests under loose bark. Like other jumping spiders, S. incana males use elaborate visual displays (Type I courtship) when they encounter females in the open. Male jumping spiders usually rely on silk-borne vibrations to communicate with females residing within retreats and nests (Type II courtship). S. incana often uses visual displays in this context, because the thin silken walls allow conspecifics to see each other. Adult males that encounter subadult females at retreats sometimes build their own retreat nearby and cohabit until the subadult female moults to maturity, copulating shortly afterwards. Adult females and immature stages of both sexes possess similar display repertoires that contain fewer display elements than the repertoire of males. We found no evidence that visual displays of S. incana contain seismic elements, in contrast to some of its closest relatives. S. incana preys upon a variety of small arthropods and, unusually amongst salticids, ants make up a large portion of the diet. Identified enemies of S. incana include spiders, a pompilid wasp and a mantispid.
Atomic-resolution structure of the CAP-Gly domain of dynactin on polymeric microtubules determined by magic angle spinning NMR spectroscopy
Authors: Yan Si , Guo Changmiao , Hou Guangjin , Zhang Huilan , Lu Xingyu , Williams John Charles , Polenova Tatyana
Published: November 2015

Significance

Microtubules and their associated proteins are central to most cellular functions. They have been extensively studied at multiple levels of resolution; however, significant knowledge gaps remain. Structures of microtubule-associated proteins bound to microtubules are not known at atomic resolution. We used magic angle spinning NMR to solve a structure of dynactin’s cytoskeleton-associated protein glycine-rich (CAP-Gly) domain bound to microtubules and to determine the intermolecular interface, the first example, to our knowledge, of the atomic-resolution structure of a microtubule-associated protein on polymeric microtubules. The results reveal remarkable structural plasticity of CAP-Gly, which enables CAP-Gly’s binding to microtubules and other binding partners. This approach offers atomic-resolution information of microtubule-binding proteins on microtubules and opens up the possibility to study critical parameters such as protonation states, strain, and dynamics on multiple time scales.
Filling constraints for spin-orbit coupled insulators in symmorphic and nonsymmorphic crystals
Authors: Watanabe Haruki , Po Hoi Chun , Vishwanath Ashvin , Zaletel Michael
Published: November 2015

Significance

Quantum spin liquids are exotic insulators in which the electron’s spin, charge, and fermionic statistics are carried by separate excitations. They have received attention for their potential as a quantum memory and as a parent state for high-temperature superconductivity. A key principle guiding the search for experimental candidate materials is the absence of conventional order in insulators at “fractional” electron filling. Previous results established what constitutes fractional filling, but assumed symmetries that are typically not respected in real materials or considered only simple lattices. Here, assuming only physical symmetries we establish filling conditions for all 230 space groups. This should aid in the search for quantum spin liquids and topological semimetals.