bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the “naming game” with learning errors in communications
Authors: Lou Yang , Chen Guanrong
Published: July 2015

Naming game simulates the process of naming an objective by a population of agents organized in a certain communication network. By pair-wise iterative interactions, the population reaches consensus asymptotically. We study naming game with communication errors during pair-wise conversations, with error rates in a uniform probability distribution. First, a model of naming game with learning errors in communications (NGLE) is proposed. Then, a strategy for agents to prevent learning errors is suggested. To that end, three typical topologies of communication networks, namely random-graph, small-world and scale-free networks, are employed to investigate the effects of various learning errors. Simulation results on these models show that 1) learning errors slightly affect the convergence speed but distinctively increase the requirement for memory of each agent during lexicon propagation; 2) the maximum number of different words held by the population increases linearly as the error rate increases; 3) without applying any strategy to eliminate learning errors, there is a threshold of the learning errors which impairs the convergence. The new findings may help to better understand the role of learning errors in naming game as well as in human language development from a network science perspective.
Tuning the Emission of Cationic Iridium (III) Complexes Towards the Red Through Methoxy Substitution of the Cyclometalating Ligand
Authors: Hasan Kamrul , Bansal Ashu K. , Samuel Ifor D.W. , Roldán-Carmona Cristina , Bolink Henk J. , Zysman-Colman Eli
Published: July 2015

The synthesis, characterization and evaluation in solid-state devices of a series of 8 cationic iridium complexes bearing different numbers of methoxy groups on the cyclometallating ligands are reported. The optoelectronic characterization showed a dramatic red shift in the absorption and the emission and a reduction of the electrochemical gap of the complexes when a methoxy group was introduced para to the Ir-C bond. The addition of a second or third methoxy group did not lead to a significant further red shift in these spectra. Emission maxima over the series ranged from 595 to 730 nm. All complexes possessing a motif with a methoxy group at the 3-position of the cyclometalating ligands showed very short emission lifetimes and poor photoluminescence quantum yields whereas complexes having a methoxy group at the 4-position were slightly blue shifted compared to the unsubstituted parent complexes, resulting from the inductively electron withdrawing nature of this directing group on the Ir-C bond. Light-emitting electrochemical cells were fabricated and evaluated. These deep red emitters generally showed poor performance with electroluminescence mirroring photoluminescence. DFT calculations accurately modelled the observed photophysical and electrochemical behavior of the complexes and point to an emission from a mixed charge transfer state.
Understanding of the low temperature auto-oxidation scheme of sec-alcohols based on a Cu(ii)-MOF with open metal sites
Authors: Ma Jian-Ping , Zhao Chao-Wei , Wang Shen-Qing , Zhang Jin-Ping , Niu Xue , Dong Yu-Bin
Published: July 2015

Confirmation of a low temperaturesec-alcohol auto-oxidation scheme based on a Cu(ii)-MOF with metal open sites.
Reactivity of a pyridinium-substituted dimethyldihydropyrene switch under aerobic conditions: self-sensitized photo-oxygenation and thermal release of singlet oxygen
Authors: Cobo Saioa , Lafolet Frédéric , Saint-Aman Eric , Philouze Christian , Bucher Christophe , Silvi Serena , Credi Alberto , Royal Guy
Published: July 2015

A reversible photo-switch is converted into an endoperoxide when irradiated with red light under air. This photo-produced species thermally releases 1O2.
Recent trends in the development of vitamin B12derivatives for medicinal applications
Authors: Zelder Felix
Published: July 2015

This Feature Article highlights recent developments in the field of vitamin B12derivatives for medicinal applications.
Enantio-differentiation of molecules with diverse functionalities using a single probe
Authors: Lakshmipriya A. , Chaudhari Sachin R. , Suryaprakash N.
Published: July 2015

Chiral discrimination of molecules with diverse functionalities using a single CSA.
Hierarchical architectured MnCO3 microdumbbells: facile synthesis and enhanced performance for lithium ion batteries
Authors: Zhang Liu , Mei Tao , Wang Xianbao , Wang Jianying , Li Jinhua , Xiong Weilai , Chen Yi , Hao Ming
Published: July 2015

Hierarchical architectured MnCO3 microdumbbells and lamellar structured MnCO3 nanosheets were selectively synthesized by a facile reflux route.
Exploring the influence of steric hindrance and electronic nature of substituents in the supramolecular arrangements of 5-(substituted phenyl)-2-formylpyrroles
Authors: Figueira Cláudia A. , Lopes Patrícia S. , Gomes Clara S. B. , Veiros Luís F. , Gomes Pedro T.
Published: July 2015

The supramolecular arrangements of 5-(substituted phenyl)-2-formylpyrroles display the core formation of dimers, tetramers or polymers, depending on the phenyl substituents.
Core-structure-inspired asymmetric addition reactions: enantioselective synthesis of dihydrobenzoxazinone- and dihydroquinazolinone-based anti-HIV agents
Authors: Li Shen , Ma Jun-An
Published: July 2015

An overview of the asymmetric synthesis of dihydrobenzoxazinone- and dihydroquinazolinone-based anti-HIV agents (Efavirenz, DPC 961, DPC 963, DPC 083) and analogues was presented.
Modeling approaches to predict removal of trace organic compounds by ozone oxidation in potable reuse applications
Authors: Park Minkyu , Anumol Tarun , Snyder Shane A.
Published: July 2015

Realized and potential threats of water scarcity due in part to global climate change have increased the interest in potable reuse of municipal wastewater.
Multicolour single molecule emission and excitation spectroscopy reveals extensive spectral shifts
Authors: Piatkowski Lukasz , Gellings Esther , van Hulst Niek F.
Published: July 2015

We explore the distribution and shape of single molecule spectra at room temperature, when embedded in a polymer host. Multicolour excitation and emission spectroscopy is implemented to capture the full inhomogeneous distribution. We observe dramatic spectral changes in a distribution of single quaterrylene diimide (QDI) molecules isolated in a PMMA matrix. The molecules are strongly blue shifted with respect to the ensemble absorption maximum and spread over a staggering 200 nm range. Despite these strong shifts, the shape of the emission spectra does not differ much between individual molecules. We demonstrate that a considerable number of molecules may be invisible in single molecule experiments, as they typically rely on only a single excitation wavelength, which predetermines which subensemble is probed in the experiment. Lastly, we make a first step towards single molecule excitation spectroscopy under ambient conditions, which allows us to determine the spectral range at which individual molecules absorb light most efficiently. We show how single molecule emission and excitation spectroscopies can complement each other and a combination of both techniques can help in understanding the origin of underlaying spectral properties of individual molecules.
Plasma membrane permeabilisation by ionic liquids: a matter of charge
Authors: Hartmann Diego O. , Shimizu Karina , Siopa Filipa , Leitão M. Cristina , Afonso Carlos A. M. , Canongia Lopes José N. , Silva Pereira Cristina
Published: July 2015

The negatively charged membrane surface hinders permeabilisation by ionic liquid long lipophilic anions – a new rule of thumb for the design of greener solvents.
Simultaneous MEMS-based electro-mechanical phenotyping of breast cancer
Authors: Pandya Hardik J. , Park Kihan , Chen Wenjin , Chekmareva Marina A. , Foran David J. , Desai Jaydev P.
Published: July 2015

MEMS-based flexible sensor for simultaneous electro-mechanical characterization of breast tissue for cancer diagnosis.
Crystal structures and photocatalytic properties of two novel iodoplumbate hybrids templated by multivalent organic cations
Authors: Wang Chao-Hai , Du Hai-Juan , Li Yao , Niu Yun-Yin , Hou Hong-Wei
Published: July 2015

Two novel multivalent organic cation-templated iodoplumbate hybrids with trinuclear or 1D anionic structures and good photocatalytic performances are reported.
Optical and electrochemical properties of covalent assembled bis(4′-carboxylic phenyl terpyridyl) Ru(ii)-monolayer
Authors: Mondal Prakash Chandra
Published: July 2015

Monomolecular layers of Ru(ii)-4′carboxylicphenyl-terpyridyl complex are prepared on glass and ITO-coated glass substrates. The optical, electrochemical and stability studies indicate that the present system is highly robust.
An efficient microwave-assisted synthesis of cotinine and iso-cotinine analogs from an Ugi-4CR approach
Authors: Polindara-García Luis A. , Montesinos-Miguel Dario , Vazquez Alfredo
Published: July 2015

A convenient synthesis of cotinine and iso-cotinine analogs featuring an Ugi-4CR/cyclization approach.
Unraveling the intramolecular cyclization mechanism of oxidized tryptophan in aqueous solution as a function of pH
Authors: Méndez-Hurtado Jefferson , Menéndez M. Isabel , López Ramón , Ruiz-López Manuel F.
Published: July 2015

pH tunes the mechanism of the intramolecular cyclization of 3a-substituted tryptophan derivatives.
Synthesis of block or graft copolymers containing poly(styrene derivative) segments by living cationic polymerization using acetal moieties as latent initiating sites
Authors: Yokoyama Norifumi , Yoshida Hirotoshi , Kanazawa Arihiro , Kanaoka Shokyoku , Aoshima Sadahito
Published: July 2015

Block and graft copolymers were synthesized via acetal-initiated living cationic polymerizations of p-methylstyrene using poly(vinyl ether)s with acetal moieties.
l-Lactide polymerization catalysed by tin(ii) 2-ethyl-hexanoate. A deeper look at chain transfer reactions
Authors: Sosnowski Stanislaw , Lewinski Piotr
Published: July 2015

Segmental exchange reactions inl-lactide polymerization catalysed by tin octoate yield chains with even and odd numbers of lactoyl units. The efficiency of the reactions depends on the position of the attacked unit in the chain. The terminal units are at least 100 times more reactive than others.
Spiroplakortone, an unprecedented spiroketal lactone from the Chinese sponge Plakortis simplex
Authors: Chianese Giuseppina , Gu Bin-Bin , Yang Fan , Jiao Wei-Hua , Guo Yue-Wei , Lin Hou-Wen , Taglialatela-Scafati Orazio
Published: July 2015

Spiroplakortone, bearing an unprecedented γ-spiroketal-γ-lactone skeleton, has been characterized based on extensive spectroscopic analysis, GIAO 13C-NMR and ECD calculations.
Effects of metal ion concentration on electrodeposited CuZnSn film and its application in kesterite Cu2ZnSnS4 solar cells
Authors: Hreid Tubshin , Li Jianjun , Zhang Yi , Spratt Henry J. , Wang Hongxia , Will Geoffrey
Published: July 2015

The influence of metal cation concentrations on the composition, morphology and alloy formation of co-electrodeposited CuZnSn film was investigated.
Facile iron(iii)-mediated ATRP of MMA with phosphorus-containing ligands in the absence of any additional initiators
Authors: Bai Liangjiu , Wang Wenxiang , Chen Hou , Zhang Lifen , Cheng Zhenping , Zhu Xiulin
Published: July 2015

Fe(iii)-mediated ATRP using phosphorus reagents was studied without any additional initiator and reducing agent. The polymerization was demonstrated as reverse ATRP, in which phosphorus reagents acted as both ligand and thermal radical initiator.
Histidine-mediated synthesis of chiral fluorescence gold nanoclusters: insight into the origin of nanoscale chirality
Authors: Guo Yanjia , Zhao Xijuan , Long Tengfei , Lin Min , Liu Zhongde , Huang Chengzhi
Published: July 2015

Strongly emitting chiral AuNCs are prepared and the origins of the optical activity are discussed from the viewpoint of the intrinsically chiral core model and the dissymmetric field effect.
A new fluorescence and colorimetric sensor for highly selective and sensitive detection of glucose in 100% water
Authors: Shen Youming , Zhang Xiangyang , Huang Xi , Zhang Youyu , Zhang Chunxiang , Jin Junling , Liu Xuewen , Li Haitao , Yao Shouzhuo
Published: July 2015

A new naphthalimide derivative containing hexanoic acid and boronate groups was designed and synthesized.
SiO2@NiO core–shell nanocomposites as high performance anode materials for lithium-ion batteries
Authors: Wang Yourong , Zhou Wei , Zhang Liping , Song Guangsen , Cheng Siqing
Published: July 2015

A SiO2@NiO core–shell electrode exhibits almost 100% coulombic efficiency, excellent cycling stability and rate capability after the first few cycles.
Study of formaldehyde adsorption on silicene with point defects by DFT method
Authors: Wang Xiao , Liu Huazhong , Tu Shan-Tung
Published: July 2015

To explore the chemical activity and sorption capacity of silicene with point defects for formaldehyde (HCHO), interactions between HCHO and silicene were investigated using density functional theory (DFT) calculations.
Communicating With a Cleft Palate Team: Improving Coordination of Care Across Treatment Settings
Authors: Dailey Scott , Wilson Kris
Published: July 2015

Patients with cleft palate with and without cleft lip, and/or velopharyngeal insufficiency (VPI) present with complex speech disorders that require both surgical and therapeutic interventions. Because of their complex needs, best practices indicate that individuals should be followed by a Cleft Palate Team in order to provide care in a coordinated fashion. Collaboration between SLPs in the community and SLPs on a Cleft Palate Team is a critical aspect to ensuring optimal speech outcomes for patients with clefts/VPI. Collaboration and communication between the SLPs may take different avenues and different timelines based on the needs of the patient and resources available.
User experience with electric vehicles while driving in a critical range situation – a qualitative approach
Authors: Rauh Nadine , Franke Thomas , Krems Josef F.
Published: July 2015

A frequently discussed phenomenon within the context of battery electric vehicles (BEVs) is range anxiety. Range anxiety is defined as a domain‐specific form of psychological stress, which can occur in a critical range situation. The objective of the present study is to better understand user experience in critical range situations (i.e. range anxiety). After driving a BEV in a critical range situation on an unaccompanied trip of 94 km length, 68 participants were asked about experienced stress‐inducing and stress‐reducing factors, as well as ideas for additional stress‐reducing strategies. The available range safety buffer and the uncertainty regarding the energy consumption of the BEV could be identified as central factors related to user experience in critical range situations. The obtained results can be utilised to formulate design recommendations to help future BEV users to better handle critical range situations. Installing displays which allow for accurate tracking of the range safety buffer or providing knowledge to reduce uncertainty might be a good starting point for improving user experience.
Role of direct electron-phonon coupling across metal-semiconductor interfaces in thermal transport via molecular dynamics
Authors: Lin Keng-Hua , Strachan Alejandro
Published: July 2015

Motivated by significant interest in metal-semiconductor and metal-insulator interfaces and superlattices for energy conversion applications, we developed a molecular dynamics-based model that captures the thermal transport role of conduction electrons in metals and heat transport across these types of interface. Key features of our model, denoted eleDID (electronic version of dynamics with implicit degrees of freedom), are the natural description of interfaces and free surfaces and the ability to control the spatial extent of electron-phonon (e-ph) coupling. Non-local e-ph coupling enables the energy of conduction electrons to be transferred directly to the semiconductor/insulator phonons (as opposed to having to first couple to the phonons in the metal). We characterize the effect of the spatial e-ph coupling range on interface resistance by simulating heat transport through a metal-semiconductor interface to mimic the conditions of ultrafast laser heating experiments. Direct energy transfer from the conduction electrons to the semiconductor phonons not only decreases interfacial resistance but also increases the ballistic transport behavior in the semiconductor layer. These results provide new insight for experiments designed to characterize e-ph coupling and thermal transport at the metal-semiconductor/insulator interfaces.
Effects of magnetic drift tangential to magnetic surfaces on neoclassical transport in non-axisymmetric plasmas
Authors: Matsuoka Seikichi , Satake Shinsuke , Kanno Ryutaro , Sugama Hideo
Published: July 2015

In evaluating neoclassical transport by radially local simulations, the magnetic drift tangential to a flux surface is usually ignored in order to keep the phase-space volume conservation. In this paper, effect of the tangential magnetic drift on the local neoclassical transport is investigated. To retain the effect of the tangential magnetic drift in the local treatment of neoclassical transport, a new local formulation for the drift kinetic simulation is developed. The compressibility of the phase-space volume caused by the tangential magnetic drift is regarded as a source term for the drift kinetic equation, which is solved by using a two-weight δf Monte Carlo method for non-Hamiltonian system [G. Hu and J. A. Krommes, Phys. Plasmas 1, 863 (1994)]. It is demonstrated that the effect of the drift is negligible for the neoclassical transport in tokamaks. In non-axisymmetric systems, however, the tangential magnetic drift substantially changes the dependence of the neoclassical transport on the radial electric field Er. The peaked behavior of the neoclassical radial fluxes around Er = 0 observed in conventional local neoclassical transport simulations is removed by taking the tangential magnetic drift into account.
Fast and sensitive method for detecting volatile species in liquids
Authors: Trimarco Daniel B. , Pedersen Thomas , Hansen Ole , Chorkendorff Ib , Vesborg Peter C. K.
Published: July 2015

This paper presents a novel apparatus for extracting volatile species from liquids using a “sniffer-chip.” By ultrafast transfer of the volatile species through a perforated and hydrophobic membrane into an inert carrier gas stream, the sniffer-chip is able to transport the species directly to a mass spectrometer through a narrow capillary without the use of differential pumping. This method inherits features from differential electrochemical mass spectrometry (DEMS) and membrane inlet mass spectrometry (MIMS), but brings the best of both worlds, i.e., the fast time-response of a DEMS system and the high sensitivity of a MIMS system. In this paper, the concept of the sniffer-chip is thoroughly explained and it is shown how it can be used to quantify hydrogen and oxygen evolution on a polycrystalline platinum thin film in situ at absolute faradaic currents down to ∼30 nA. To benchmark the capabilities of this method, a CO-stripping experiment is performed on a polycrystalline platinum thin film, illustrating how the sniffer-chip system is capable of making a quantitative in situ measurement of <1 % of a monolayer of surface adsorbed CO being electrochemically stripped off an electrode at a potential scan-rate of 50 mV s−1.
An origin of good electrical conduction in La4BaCu5O13+δ
Authors: Mori Daiki , Asai Shinichiro , Terasaki Ichiro , Okazaki Ryuji , Yasui Yukio , Parkkima Outi , Karppinen Maarit
Published: July 2015

We have prepared a set of polycrystalline samples of the metallic copper oxide La4BaCu5−xCoxO13+δ (0 ≤ x ≤ 0.35) and have measured the resistivity from 4 to 800 K. All the resistivities show metallic temperature dependence with a small magnitude less than 2 mΩ cm at 800 K, indicating that the metallic conduction is robust against impurities. The robust metallic conduction further suggests that this class of oxide is a promising candidate for electrical leads at high temperature, which might replace platinum. A detailed measurement and analysis on the Hall resistivity have revealed that at least two components are responsible for the electrical conduction, in which a large number of electrons of moderate mobility coexist with a much smaller number of holes of extremely high mobility. This large electron density well screens the impurity potential and retains the metallic conduction against 7% impurity doping.
Experimental investigation and numerical modeling of the effect of voltage parameters on the characteristics of low-pressure argon dielectric barrier discharges
Authors: Barjasteh Azadeh , Eslami Esmaeil , Morshedian Nader
Published: July 2015

In this paper, we have presented the experimental and modeling results of the effect of voltage parameters on the characteristics of the low-pressure Ar dielectric barrier discharge. The frequency and amplitude range was set at 5–19 kHz and 255–370 V, respectively. Our investigations showed that the voltage parameters such as amplitude and frequency have large impact on the discharge behavior. Increase in applied voltage amplitude leads to an increase in discharge current. It is also shown that with increasing applied voltage amplitude, the plasma radiations are increased and move to the middle of discharge gap. Also, it causes that surface charge density is increased and discharge is distributed on the dielectric surface. With increasing voltage frequency, discharge current and plasma radiations are increased, but discharge is not distributed on the dielectrics surface. It is also shown that with increasing voltage frequency and amplitude, the discharge kinetic is changed.
Beam emittance measurements and simulations of injector line for radio frequency quadrupole
Authors: Mathew Jose V. , Rao S. V. L. S. , Pande Rajni , Singh P.
Published: July 2015

A 400 keV deuteron (D+) radio frequency quadrupole (RFQ) accelerator has been designed, built, and commissioned at the Bhabha Atomic Research Centre, India. A beam line has been developed for injecting deuterons into the 400 keV RFQ. This comprises of a RF plasma ion source and a low energy beam transport (LEBT) system, consisting of two solenoid magnets and two steerer magnets. The ion source is characterized in terms of transverse beam emittance. A slit-wire scanner based emittance measurement setup has been developed for the transverse emittance measurements of H+ and D+ beams. The measured emittance values are found to be well within the acceptance value for the RFQ. These measured emittance parameters are used to optimize the solenoid fields in LEBT to match the beam from the ion source to RFQ. TRACEWIN simulation code is used for the beam transport simulations. The simulations show 99% transmission of D+ beam through the RFQ, while 95% transmission has been measured experimentally.
Simulative research on the anode plasma dynamics in the high-power electron beam diode
Authors: Cai Dan , Liu Lie , Ju Jin-Chuan , Zhang Tian-Yang , Zhao Xue-Long , Zhou Hong-Yu
Published: July 2015

Anode plasma generated by electron beams could limit the electrical pulse-length, modify the impedance and stability of diode, and affect the generator to diode power coupling. In this paper, a particle-in-cell code is used to study the dynamics of anode plasma in the high-power electron beam diode. The effect of gas type, dynamic characteristic of ions on the diode operation with bipolar flow model are presented. With anode plasma appearing, the amplitude of diode current is increased due to charge neutralizations of electron flow. The lever of neutralization can be expressed using saturation factor. At same pressure of the anode gas layer, the saturation factor of CO2 is bigger than the H2O vapor, namely, the generation rate of C+ ions is larger than the H+ ions at the same pressure. The transition time of ions in the anode-cathode gap could be used to estimate the time of diode current maximum.
Ablation dynamics in wire array Z-pinches under modifications on global magnetic field topology
Authors: Veloso Felipe , Muñoz-Cordovez Gonzalo , Donoso-Tapia Luis , Valenzuela-Villaseca Vicente , Suzuki-Vidal Francisco , Swadling George , Chittenden Jeremy , Favre Mario , Wyndham Edmund
Published: July 2015

The dynamics of ablation streams and precursor plasma in cylindrical wire array Z-pinches under temporal variations of the global magnetic field topology is investigated through experiments and numerical simulations. The wire arrays in these experiments are modified by replacing a pair of consecutive wires with wires of a larger diameter. This modification leads to two separate effects, both of which impact the dynamics of the precursor plasma; firstly, current is unevenly distributed between the wires and secondly, the thicker wires take longer to fully ablate. The uneven distribution of current is evidenced in the experiments by the drift of the precursor off axis due to a variation in the global magnetic field topology which modifies the direction of the ablation streams tracking the precursor position. The variation of the global magnetic field due to the presence of thick wires is studied with three-dimensional magnetohydrodynamic (MHD) simulations, showing that the global field changes from the expected toroidal field to a temporally variable topology after breakages appear in the thin wires. This leads to an observed acceleration of the precursor column towards the region closer to the thick wires and later, when thick wires also present breakages, it continues moving away from the original array position as a complicated and disperse object subject to MHD instabilities
Molecular reorganization of selected quinoline derivatives in the ground and excited states—Investigations via static DFT
Authors: Błaziak Kacper , Panek Jarosław J. , Jezierska Aneta
Published: July 2015

Quinoline derivatives are interesting objects to study internal reorganizations due to the observed excited-state-induced intramolecular proton transfer (ESIPT). Here, we report on computations for selected 12 quinoline derivatives possessing three kinds of intramolecular hydrogen bonds. Density functional theory was employed for the current investigations. The metric and electronic structure simulations were performed for the ground state and first excited singlet and triplet states. The computed potential energy profiles do not show a spontaneous proton transfer in the ground state, whereas excited states exhibit this phenomenon. Atoms in Molecules (AIM) theory was applied to study the nature of hydrogen bonding, whereas Harmonic Oscillator Model of aromaticity index (HOMA) provided data of aromaticity evolution as a derivative of the bridge proton position. The AIM-based topological analysis confirmed the presence of the intramolecular hydrogen bonding. In addition, using the theory, we were able to provide a quantitative illustration of bonding transformation: from covalent to the hydrogen. On the basis of HOMA analysis, we showed that the aromaticity of both rings is dependent on the location of the bridge proton. Further, the computed results were compared with experimental data available. Finally, ESIPT occurrence was compared for the three investigated kinds of hydrogen bridges, and competition between two bridges in one molecule was studied.
The photoexcitation of crystalline ice and amorphous solid water: A molecular dynamics study of outcomes at 11 K and 125 K
Authors: Crouse J. , Loock H.-P. , Cann N. M.
Published: July 2015

Photoexcitation of crystalline ice Ih and amorphous solid water at 7-9 eV is examined using molecular dynamics simulations and a fully flexible water model. The probabilities of photofragment desorption, trapping, and recombination are examined for crystalline ice at 11 K and at 125 K and for amorphous solid water at 11 K. For 11 K crystalline ice, a fully rigid water model is also employed for comparison. The kinetic energy of desorbed H atoms and the distance travelled by trapped fragments are correlated to the location and the local environment of the photoexcited water molecule. In all cases, H atom desorption is found to be the most likely outcome in the top bilayer while trapping of all photofragments is most probable deeper in the solid where the likelihood for recombination of the fragments into H2O molecules also rises. Trajectory analysis indicates that the local hydrogen bonding network in amorphous solid water is more easily distorted by a photodissociation event compared to crystalline ice. Also, simulations indicate that desorption of OH radicals and H2O molecules are more probable in amorphous solid water. The kinetic energy distributions for desorbed H atoms show a peak at high energy in crystalline ice, arising from photoexcited water molecules in the top monolayer. This peak is less pronounced in amorphous solid water. H atoms that are trapped may be displaced by up to ∼10 water cages, but migrate on average 3 water cages. Trapped OH fragments tend to stay near the original solvent cage.
Can quantum coherent solar cells break detailed balance?
Authors: Kirk Alexander P.
Published: July 2015

Carefully engineered coherent quantum states have been proposed as a design attribute that is hypothesized to enable solar photovoltaic cells to break the detailed balance (or radiative) limit of power conversion efficiency by possibly causing radiative recombination to be suppressed. However, in full compliance with the principles of statistical mechanics and the laws of thermodynamics, specially prepared coherent quantum states do not allow a solar photovoltaic cell—a quantum threshold energy conversion device—to exceed the detailed balance limit of power conversion efficiency. At the condition given by steady-state open circuit operation with zero nonradiative recombination, the photon absorption rate (or carrier photogeneration rate) must balance the photon emission rate (or carrier radiative recombination rate) thus ensuring that detailed balance prevails. Quantum state transitions, entropy-generating hot carrier relaxation, and photon absorption and emission rate balancing are employed holistically and self-consistently along with calculations of current density, voltage, and power conversion efficiency to explain why detailed balance may not be violated in solar photovoltaic cells.
Quantum paraelectricity in copper-titanates: Magnetic-order driven vitrification
Authors: Kumar Jitender , Awasthi A. M.
Published: July 2015

Quantum-paraelectric (QP) family character is emergent from shared low-temperature characteristics of SrCu3Ti4O12 (SCTO), CaCu3Ti4O12 (CCTO), and Ca0.9Li0.1Cu3Ti4O12 (CLCTO) A1/4A′3/4BO3 structures featuring antiferro-tilted Ti-O6 octahedra. Above their magnetic ordering temperatures TN, permittivity of SCTO and CLCTO follow typical Barrett form, whereas in CCTO, quantum paraelectricity is masked by the huge ε′-step. Hidden QP in CCTO gets revealed by Li-doping at the Ca-site, which considerably up-shifts the temperature scale (from ∼100 K to ∼250 K) of the dielectric step-anomaly in CLCTO. Competing magneto-electricity and quantum fluctuations result in glassy-arrest of the QP degrees of freedom near TN; manifest as dispersive-deviation of the permittivity (in SCTO and CLCTO) from the low-temperature Barrett saturation. However, quantum criticality (QC) regime being well above TN registers its presence nevertheless, as the ∼T2 behaviour of their inverse dielectric susceptibility. Non-compliance to the usual behaviours of dispersive-response vs. bias-field and temperature unambiguously rule out a relaxor origin of the glassy state. We determine a dimensionless thermal window (0.3 ≤ T/T1 ≤ 0.6) of QC signature, covering typical quantum-paraelectrics.
Magnetic phase characterization of nanocrystalline La2NiMnO6 using alternating current conductance
Authors: Chakraborty D. , Nandi U. N. , Jana D. , Masud Md G. , Giri S.
Published: July 2015

The signature of various disordered phases is inferred from the measurement of the real part of alternating current conductance Σ(T, f) of a nanocrystalline double perovskite La2NiMnO6. The system exhibits a paramagnetic insulating (PMI) phase at high temperatures, a ferromagnetic insulating (FMI) phase at low temperatures, and a Griffiths-like phase in the intermediate temperature range. In these three phases, Σ(T, f) shows qualitatively similar variation with frequency f. At a fixed temperature T, Σ(T, f) remains constant to its Ohmic value Σ0 up to a certain frequency, known as the onset frequency fc and increases with increasing f beyond fc. Scaled appropriately, Σ(T, f) versus f data corresponding to these three regimes fall on the same master curve indicating the universal nature of the scaling behaviour of alternating current conductance. This onset frequency fc scales with Σ0 as fc∼Σ0xf with xf as the nonlinearity exponent. This exponent xf shows a gradual crossover from 1.025 ± 0.006 in FMI phase to 0.518 ± 0.07 in PMI phase in an intermediate temperature range signifying the presence of Griffiths-like phase. A simple phenomenological R–RC model consistent with the microstructural conduction mechanisms in PMI and FMI phases is developed to generate the qualitative non-Ohmic character of ac conductance, the onset frequency fc, and the nonlinearity exponent xf. Existing scaling theories with reliable models are used to analyze and compare the results of ac conductance in similar systems.
Structural and electronic properties of GaN nanowires with embedded InxGa1−xN nanodisks
Authors: Kioseoglou J. , Pavloudis Th. , Kehagias Th. , Komninou Ph. , Karakostas Th. , Latham C. D. , Rayson M. J. , Briddon P. R. , Eickhoff M.
Published: July 2015

In the present study, the effects of various types of strain and indium concentration on the total energy and optoelectronic properties of GaN nanowires (NWs) with embedded InxGa1−xN nanodisks (NDs) are examined. In particular, the bi-axial, hydrostatic, and uniaxial strain states of the embedded InxGa1−xN NDs are investigated for multiple In concentrations. Density functional theory is employed to calculate the band structure of the NWs. The theoretical analysis finds that the supercell-size-dependent characteristics calculated for our 972-atom NW models are very close to the infinite supercell-size limit. It is established that the embedded InxGa1−xN NDs do not induce deep states in the band gap of the NWs. A bowing parameter of 1.82 eV is derived from our analysis in the quadratic Vegard's formula for the band gaps at the various In concentrations of the investigated InxGa1−xN NDs in GaN NW structures. It is concluded that up to ∼10% of In, the hydrostatic strain state is competitive with the bi-axial due to the radial absorption of the strain on the surfaces. Above this value, the dominant strain state is the bi-axial one. Thus, hydrostatic and bi-axial strain components coexist in the embedded NDs, and they are of different physical origin. The bi-axial strain comes from growth on lattice mismatched substrates, while the hydrostatic strain originates from the lateral relaxation of the surfaces.
Electronic transitions and band offsets in C60:SubPc and C60:MgPc on MoO3 studied by modulated surface photovoltage spectroscopy
Authors: Fengler S. , Dittrich Th. , Rusu M.
Published: July 2015

Electronic transitions at interfaces between MoO3 layers and organic layers of C60, SubPc, MgPc, and nano-composite layers of SubPc:C60 and MgPc:C60 have been studied by modulated surface photovoltage (SPV) spectroscopy. For all systems, time dependent and modulated SPV signals pointed to dissociation of excitons at the MoO3/organic layer interfaces with a separation of holes towards MoO3. The highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gaps (EHL) of C60, SubPc, and MgPc and the effective EHL of SubPc:C60 and MgPc:C60 were measured. The offsets between the LUMO (ΔEL) or HOMO (ΔEH) bands were obtained with high precision and amounted to 0.33 or 0.73 eV for SubPc:C60, respectively, and to −0.33 or 0.67 eV for MgPc:C60, respectively. Exponential tails below EHL and most pronounced sub-bandgap transitions were characterized and ascribed to disorder and transitions from HOMO bands to unoccupied defect states.
Proposal of a new hybrid control strategy for dynamic performance improvement of wound field synchronous generator-based wind turbines
Authors: Tahir K. , Belfedal C. , Allaoui T. , Doumi M.
Published: July 2015

This paper presents a simulation study of the control of a variable speed wind energy conversion system (WECS) using a wound field synchronous generator (WFSG). The proposed scheme is based on an RST controller with adaptive fuzzy gain scheduling (AFGS-RST) and regulates the active and reactive powers exchanged between the stator of the WFSG and the grid to ensure a Maximum Power Point Tracking of the WECS. The overall system model was implemented in MATLAB/Simulink with three different power controllers (the polynomial RST, the fuzzy logic controller, and the AFGS-RST controller). The performances of these controllers are evaluated under different operating conditions of the WECS power system. The results demonstrate that AFGS-RST controller is very effective in improving the power flow and very robust against variable transmission line parameters compared to the two other controllers.
Pressure-induced amorphization of metavanadate crystals SrV2O6 and BaV2O6
Authors: Li Yan , Tang Ruilian , Li Nana , Li Hui , Zhao Xudong , Zhu Pinwen , Wang Xin
Published: July 2015

Lattice vibrations and electrical transport properties of SrV2O6 (SVO) and BaV2O6 (BVO) under high pressure have been investigated by Raman spectra and alternating current (AC) impedance spectra measurements. A pressure-induced structural phase transition in SVO is observed at 3.9 GPa, and the phase transition in BVO happens at 4.3 GPa from their high-pressure Raman spectra. With further increasing pressures, amorphization is found in both SVO and BVO at 10.1 and 9.3 GPa, respectively. Pressure-induced amorphization of SVO and BVO is suggested to be associated with the breaking up of infinite chains of corner-linked tetrahedral VO4 into VO3−. The recovery of original crystalline phases along with the re-linking of VO3− chains is observed after heating the reclaimed samples. Furthermore, the in situ high pressure measurements of AC impedance spectra of BVO reveal two distinct changes in its resistance, which can correspond to the transitions as observed in the Raman spectra.
Tracking the subsurface path of dislocations in GaN using scanning tunneling microscopy
Authors: Weidlich P. H. , Schnedler M. , Portz V. , Eisele H. , Strauß U. , Dunin-Borkowski R. E. , Ebert Ph.
Published: July 2015

A methodology for the determination of the subsurface line direction of dislocations using scanning tunneling microscopy (STM) images is presented. The depth of the dislocation core is derived from an analysis of the displacement field measured by STM. The methodology is illustrated for dislocations at GaN(101¯0) cleavage surfaces. It is found that the dislocation line bends toward the surface, changing from predominantly edge-type to more screw-type character, when approaching the intersection point. Simultaneously, the total displacement detectable at the surface increases due to a preferred relaxation towards the surface.
Electromagnetic fluctuations in magnetized plasmas. I. The rigorous relativistic kinetic theory
Authors: Schlickeiser R. , Yoon P. H.
Published: July 2015

Using the system of the Klimontovich and Maxwell equations, the general linear fluctuation theory for magnetized plasmas is developed. General expressions for the electromagnetic fluctuation spectra (electric and magnetic fields) from uncorrelated plasma particles in plasmas with a uniform magnetic field are derived, which are covariantly correct within the theory of special relativity. The general fluctuation spectra hold for plasmas of arbitrary composition, arbitrary momentum dependences of the plasma particle distribution functions, and arbitrary orientations of the wave vector with respect to the uniform magnetic field. Moreover, no restrictions on the values of the real and the imaginary parts of the frequency are made. The derived fluctuation spectra apply to both non-collective fluctuations and collective plasma eigenmodes in magnetized plasmas. In the latter case, kinetic equations for the components of fluctuating electric and magnetic fields in magnetized plasmas are derived that include the effect of spontaneous emission and absorption. In the limiting case of an unmagnetized plasmas, the general fluctuation spectra correctly reduce to the unmagnetized fluctuation spectra derived before.
On the electronic, structural, and thermodynamic properties of Au supported on α-Fe2O3 surfaces and their interaction with CO
Authors: Nguyen Manh-Thuong , Farnesi Camellone Matteo , Gebauer Ralph
Published: July 2015

Extensive first principles calculations are carried out to investigate Au monomers and dimers supported on α-Fe2O3(0001) surfaces in terms of structure optimizations, electronic structure analyses, and ab initio thermodynamics calculations of surface phase diagrams. All computations rely on density functional theory in the generalized gradient approximation (Perdew-Burke-Ernzerhof (PBE)) and account for on-site Coulomb interactions via inclusion of a Hubbard correction (PBE+U). The relative stability of Au monomers/dimers on the stoichiometric termination of α-Fe2O3(0001) decorated with various vacancies (multiple oxygen vacancies, iron vacancy, and mixed iron-oxygen vacancies) has been computed as a function of the oxygen chemical potential. The charge rearrangement induced by Au at the oxide contact is analyzed in detail and discussed. On one hand, ab initio thermodynamics predicts that under O-rich conditions, structures obtained by replacing a surface Fe atom with a Au atom are thermodynamically stable over a wide range of temperatures. On the other hand, the complex of a CO molecule on a Au atom substituting surface Fe atoms is thermodynamically stable only in a much more narrow range of values of the O chemical potential under O-rich conditions. In the case of a Au dimer, under O-rich conditions, supported Au atoms at an O-Fe di-vacancy are more stable. However, upon CO adsorption, the complex of a CO molecule and 2 Au atoms located at a single Fe vacancy is more favorable.
Study of non-linear Hall effect in nitrogen-grown ZnO microstructure and the effect of H+-implantation
Authors: Kumar Yogesh , Bern Francis , Barzola-Quiquia Jose , Lorite Israel , Esquinazi Pablo
Published: July 2015

We report magnetotransport studies on microstructured ZnO film grown by pulsed laser deposition in N2 atmosphere on a-plane Al2O3 substrates and the effect of low energy H+-implantation. Non-linearity has been found in the magnetic field dependent Hall resistance, which decreases with temperature. We explain this effect with a two-band model assuming the conduction through two different parallel channels having different types of charge carriers. Reduced non-linearity after H+-implantation in the grown film is due to the shallow-donor effect of hydrogen giving rise to an increment in the electron density, reducing the effect of the other channel.
Electric field-controlled magnetization in bilayered magnetic films for magnetoelectric memory
Authors: Yang Wei-Gang , Morley Nicola A. , Rainforth W. Mark
Published: July 2015

Bilayered magnetic films (Co50Fe50 (CoFe)/Metglas) were RF sputtered on both (001)-oriented and (011)-oriented PMN-PT (lead magnesium niobate-lead titanate) substrates. Electric field-controlled magnetization changes were observed in all these samples: 65 nm CoFe/24 nm Metglas/(001) PMN-PT, 65 nm CoFe/24 nm Metglas/(011) PMN-PT, and 30 nm CoFe/12 nm Metglas/(011) PMN-PT. The maximum magnetic remanence ratio change (ΔMr/Ms) was 46% for CoFe/Metglas/(001) PMN-PT. In this heterostructure, the electric-field created two new non-volatile switchable remanence states and the as-grown remanence state was altered permanently. High-resolution transmission electron microscopy images show a sharp and smooth interface between Metglas and substrate and conversely a rougher interface was observed between Metglas and CoFe films. In the 30 nm CoFe/12 nm Metglas/(011) PMN-PT sample, a large ΔMr/Ms of 80% along the [100] direction was measured, while the ΔMr/Ms along the [01-1] direction was 60% at the applied electric field of 5 kV/cm, corresponding to a giant magnetoelectric coupling constant α = μoΔMr/E = 2.9 × 10−6 s/m.
Note: Design and development of wireless controlled aerosol sampling network for large scale aerosol dispersion experiments
Authors: Gopalakrishnan V. , Subramanian V. , Baskaran R. , Venkatraman B.
Published: July 2015

Wireless based custom built aerosol sampling network is designed, developed, and implemented for environmental aerosol sampling. These aerosol sampling systems are used in field measurement campaign, in which sodium aerosol dispersion experiments have been conducted as a part of environmental impact studies related to sodium cooled fast reactor. The sampling network contains 40 aerosol sampling units and each contains custom built sampling head and the wireless control networking designed with Programmable System on Chip (PSoC™) and Xbee Pro RF modules. The base station control is designed using graphical programming language LabView. The sampling network is programmed to operate in a preset time and the running status of the samplers in the network is visualized from the base station. The system is developed in such a way that it can be used for any other environment sampling system deployed in wide area and uneven terrain where manual operation is difficult due to the requirement of simultaneous operation and status logging.
Thermal transport in tantalum oxide films for memristive applications
Authors: Landon Colin D. , Wilke Rudeger H. T. , Brumbach Michael T. , Brennecka Geoff L. , Blea-Kirby Mia , Ihlefeld Jon F. , Marinella Matthew J. , Beechem Thomas E.
Published: July 2015

The thermal conductivity of amorphous TaOx memristive films having variable oxygen content is measured using time domain thermoreflectance. Thermal transport is described by a two-part model where the electrical contribution is quantified via the Wiedemann-Franz relation and the vibrational contribution by the minimum thermal conductivity limit for amorphous solids. The vibrational contribution remains constant near 0.9 W/mK regardless of oxygen concentration, while the electrical contribution varies from 0 to 3.3 W/mK. Thus, the dominant thermal carrier in TaOx switches between vibrations and charge carriers and is controllable either by oxygen content during deposition, or dynamically by field-induced charge state migration.
Silicon-based three-dimensional microstructures for radiation dosimetry in hadrontherapy
Authors: Guardiola C. , Quirion D. , Pellegrini G. , Fleta C. , Esteban S. , Cortés-Giraldo M. A. , Gómez F. , Solberg T. , Carabe A. , Lozano M.
Published: July 2015

In this work, we propose a solid-state-detector for use in radiation microdosimetry. This device improves the performance of existing dosimeters using customized 3D-cylindrical microstructures etched inside silicon. The microdosimeter consists of an array of micro-sensors that have 3D-cylindrical electrodes of 15 μm diameter and a depth of 5 μm within a silicon membrane, resulting in a well-defined micrometric radiation sensitive volume. These microdetectors have been characterized using an 241Am source to assess their performance as radiation detectors in a high-LET environment. This letter demonstrates the capability of this microdetector to be used to measure dose and LET in hadrontherapy centers for treatment plan verification as part of their patient-specific quality control program.