bluuebunny/crossref_metadata_2025 huggingface dataset:
THE HOURS WORKED–PRODUCTIVITY PUZZLE: IDENTIFICATION IN A FRACTIONAL INTEGRATION SETTING
Authors: Lovcha Yuliya , Perez-Laborda Alejandro
Published: April 2014

A recent finding of the SVAR literature is that the response of hours worked to a (positive) technology shock depends on the assumed order of integration of the hours. In this work we relax this assumption, allowing fractional integration in hours and productivity. We find that the sign and magnitude of the estimated responses depend crucially on the identification assumptions employed. Although the responses of hours recovered with short-run (SR) restrictions are positive in all data sets, long-run (LR) identification results in negative, although sometimes not significant responses. We check the validity of these assumptions with the Sims procedure, concluding that both LR and SR are appropriate to recover responses in a fractionally integrated VAR. However, the application of the LR scheme always results in an increase in sampling uncertainty. Results also show that even the negative responses found in the data could still be compatible with real business cycle models.
Attitudes of the German public to restrictions on persons with mental illness in 1993 and 2011
Authors: Angermeyer M. C. , Matschinger H. , Schomerus G.
Published: April 2014

Aims.

In recent years, the United Nations Convention on the Rights of Persons with Disabilities, the Mental Health Declaration for Europe and other initiatives laid the ground for improving the rights of persons with mental illness. This study aims to explore to what extent these achievements are reflected in changes of public attitudes towards restrictions on mentally ill people.

Methods.

Data from two population surveys that have been conducted in the ‘new’ States of Germany in 1993 and 2011 are compared with each other.

Results.

The proportion of respondents accepting compulsory admission of mentally ill persons to a psychiatric hospital remained unchanged in general, but the proportion opposing compulsory admission on grounds not sanctioned by law declined. In contrast, more respondents were opposed to permanently revoking the driver's license and fewer supported abortion and (voluntary) sterilisation in 2011. Concerning the right to vote and compulsory sterilisation, the proportion of those who did not give their views increased most.

Conclusions.

Two divergent trends in public attitudes towards restrictions on people with mental disorders emerge: While, in general, people's views on patients' rights have become more liberal, the public is also more inclined to restricting patients’ freedom in case of deviant behaviour.
”When You’re in the Hospital, You’re in a Sort of Bubble.”
Authors: Owen-Smith Amanda , Bennewith Olive , Donovan Jenny , Evans Jonathan , Hawton Keith , Kapur Nav , O’Connor Susan , Gunnell David
Published: April 2014

Background: Individuals are at a greatly increased risk of suicide and self-harm in the months following discharge from psychiatric hospital, yet little is known about the reasons for this. Aims: To investigate the lived experience of psychiatric discharge and explore service users’ experiences following discharge. Method: In-depth interviews were undertaken with recently discharged service users (n = 10) in the UK to explore attitudes to discharge and experiences since leaving hospital. Results: Informants had mixed attitudes to discharge, and those who had not felt adequately involved in discharge decisions, or disagreed with them, had experienced urges to self-harm since being discharged. Accounts revealed a number of factors that made the postdischarge period difficult; these included both the reemergence of stressors that existed prior to hospitalization and a number of stressors that were prompted or exacerbated by hospitalization. Conclusion: Although inferences that can be drawn from the study are limited by the small sample size, the results draw attention to a number of factors that could be investigated further to help explain the high risk of suicide and self-harm following psychiatric discharge. Findings emphasize the importance of adequate preparation for discharge and the maintenance of ongoing relationships with known service providers where possible.
Dependency structure and scaling properties of financial time series are related
Authors: Morales Raffaello , Di Matteo T. , Aste Tomaso
Published: April 2014

We report evidence of a deep interplay between cross-correlations hierarchical properties and multifractality of New York Stock Exchange daily stock returns. The degree of multifractality displayed by different stocks is found to be positively correlated to their depth in the hierarchy of cross-correlations. We propose a dynamical model that reproduces this observation along with an array of other empirical properties. The structure of this model is such that the hierarchical structure of heterogeneous risks plays a crucial role in the time evolution of the correlation matrix, providing an interpretation to the mechanism behind the interplay between cross-correlation and multifractality in financial markets, where the degree of multifractality of stocks is associated to their hierarchical positioning in the cross-correlation structure. Empirical observations reported in this paper present a new perspective towards the merging of univariate multi scaling and multivariate cross-correlation properties of financial time series.
Discrete regenerative fuel cell reduces hysteresis for sustainable cycling of water
Authors: Park Kiwon , Lee Jungkoo , Kim Hyung-Man , Choi Kap-Seung , Hwang Gunyong
Published: April 2014

The discrete regenerative fuel cell is being developed as a residential power control that synchronizes with a renewables load which fluctuates significantly with the time and weather. The power of proton exchange membrane fuel cells can be scaled-up adjustably to meet the residential power demand. As a result, scale-ups from a basic unit cell with a 25 cm2active area create a serpentine flow-field on an active area of 100 cm2and take into account the excessive current and the remaining power obtained by stacking single cells. Operating a fuel cell utilising oxygen produced by the electrolyser instead of air improves the electrochemical reaction and the water balance. Furthermore, the performance test results with oxygen instead of air show almost no hysteresis, which results in the very stable operation of the proton exchange membrane fuel cell as well as the sustainable cycle of water by hydrogen and oxygen mediums.
Exceptional capability of nanosized CeO2 materials to “dissolve” lanthanide oxides established by time-gated excitation and emission spectroscopy
Authors: Tiseanu Carmen , Parvulescu Vasile , Avram Daniel , Cojocaru Bogdan , Sanchez-Dominguez Margarita
Published: April 2014

No need for bulk doping: Impregnation of CeO2–ZrO2 with 10% Eu3+ followed by calcination stabilizes the pseudo-cubic phase of Eu–CeO2–ZrO2 with a high degree of homogeneity according to luminescence data.
Bi- and tri-metallic Rh and Ir complexes containing click derived bis- and tris-(pyrazolyl-1,2,3-triazolyl) N–N′ donor ligands and their application as catalysts for the dihydroalkoxylation of alkynes
Authors: Vuong Khuong Q. , Wong Chin M. , Bhadbhade Mohan , Messerle Barbara A.
Published: April 2014

Bi- and trimetallic Rh and Ir complexes were successfully synthesised from multitopic ‘click derived’ ligands and shown to catalysed the hydroalkoxylation of alkynes.
Triethylene glycol–titanium oxide hydrate hybrid films with high refractive index and surface evenness
Authors: Park Seung Koo , Kang Byoung-Kuk , Shin Jin-Wook , Joo Chul Woong , Moon Jaehyun , Cho Doo-Hee , Yu Byounggon , Chu Hye Yong , Lee Jeong-Ik
Published: April 2014

An organic–inorganic hybrid film fabricated from triethylene glycol–titanium oxide hydrate solution shows high refractive index (n ∼ 2.1) in the visible region and surface evenness (Ra ∼ 0.25 nm) even when it is annealed at much lower temperature than the sintering temperature of titanium dioxide.
Preparation and ion recognition features of porphyrin–chalcone type compounds as efficient red-fluorescent materials
Authors: Moura Nuno M. M. , Núñez Cristina , Faustino M. Amparo F. , Cavaleiro José A. S. , Neves M. Graça P. M. S. , Capelo José Luis , Lodeiro Carlos
Published: April 2014

The ion recognition hability of a series of synthesized porphyrins bearing an α,β-unsaturated ketone unit in a β-pyrrolic position (4a–e) was evaluated.
Surface-initiated atom transfer radical polymerization of glycidyl methacrylate and styrene from boron nitride nanotubes
Authors: Ejaz Muhammad , Rai Satish C. , Wang Kai , Zhang Karen , Zhou Weilie , Grayson Scott M.
Published: April 2014

An efficient two-step polymer grafting procedure is developed for the functionalisation of boron nitride nanotubes. Using surface-initiated atom transfer radical polymerisation, dense grafts of poly(glycidyl methacrylate) and polystyrene were grown from the nanotube surface.
A novel sandwich electrochemiluminescence aptasensor based on molybdenum disulfide nanosheet–graphene composites and Au nanoparticles for signal amplification
Authors: Liu Yan-Ming , Zhou Min , Liu Ying-Ying , Huang Ke-Jing , Cao Jun-Tao , Zhang Jing-Jing , Shi Gui-Fang , Chen Yong-Hong
Published: April 2014

In this work, we constructed a novel sandwich electrochemiluminescence aptasensor based on molybdenum disulfide nanosheet–graphene composites and Au nanoparticles.
Sandwich immunoassay for lactoferrin detection in milk powder
Authors: Liu Liqiang , Kong Dezhao , Xing Changrui , Zhang Xun , Kuang Hua , Xu Chuanlai
Published: April 2014

Lactoferrin (LF) content in infant milk powder has been strictly regulated by many governments and there is a need for convenient and reliable assays.
Efficiency enhancement of black dye-sensitized solar cells by newly synthesized D–π–A coadsorbents: a theoretical study
Authors: Azar Yavar T. , Payami Mahmoud
Published: April 2014

The electronic structure, optical properties, and adsorption geometry of two novel D–π–A coadsorbents are studied, using density functional theory and time-dependent density functional theory.
Recent aspects of self-oscillating polymeric materials: designing self-oscillating polymers coupled with supramolecular chemistry and ionic liquid science
Authors: Ueki Takeshi , Yoshida Ryo
Published: April 2014

Herein, we summarise the recent developments in self-oscillating polymeric materials based on the concepts of supramolecular chemistry, where aggregates of molecular building blocks with non-covalent bonds evolve the temporal or spatiotemporal structure.
Metalloprotein design using genetic code expansion
Authors: Hu Cheng , Chan Sunney I. , Sawyer Elizabeth B. , Yu Yang , Wang Jiangyun
Published: April 2014

Genetic code expansion has become an essential new tool for designing functional small protein models for complex metalloenzymes.
Phosphine free SBA-15–EDTA–Pd highly active recyclable catalyst: synthesis characterization and application for Suzuki and Sonogashira reaction
Authors: Sharma Priti , Singh A. P.
Published: April 2014

SBA-15–EDTA–Pd(11) was demonstrated to be a highly efficient and reusable heterogeneous catalyst for the Suzuki and Sonogashira reactions in phosphine and co-catalyst free reaction conditions.
Hydration properties determining the reactivity of nitrite in aqueous solution
Authors: Vchirawongkwin Saowapak , Kritayakornupong Chinapong , Tongraar Anan , Vchirawongkwin Viwat
Published: April 2014

Quantitative analysis of the QMCF MD trajectories requires a rigorous method to organize the chaotic data into informative data, clarifying the anisotropy of the hydration structure around the nitrite ion. These results suggested the steric effects of water in the bond directions.
Theory-assisted development of a robust and Z-selective olefin metathesis catalyst
Authors: Occhipinti Giovanni , Koudriavtsev Vitali , Törnroos Karl W. , Jensen Vidar R.
Published: April 2014

A tight interplay between theory and experiment has led to the development of a new, highly Z-selective ruthenium-based olefin metathesis catalyst that can be used in air, with unpurified and non-degassed substrates and solvents, and in the presence of acids.
Structural characterization and biological evaluation of a clioquinol–ruthenium complex with copper-independent antileukaemic activity
Authors: Gobec Martina , Kljun Jakob , Sosič Izidor , Mlinarič-Raščan Irena , Uršič Matija , Gobec Stanislav , Turel Iztok
Published: April 2014

The organoruthenium clioquinol complex induces copper-independent cell death in leukaemia cells by proteasome-independent inhibition of the NFκB signalling pathway.
Ca3Be6B5O16F: the first alkaline-earth beryllium borate with fluorine anions
Authors: Yao Wenjiao , Xu Tao , Jiang Xingxing , Huang Hongwei , Wang Xiaoyang , Lin Zheshuai , Chen Chuangtian
Published: April 2014

The first all-alkaline-earth beryllium borate with fluorine anions, Ca3Be6B5O16F, was synthesized by a spontaneous crystallization flux method using LiF–B2O3as the flux.
Three Mn(ii) coordination polymers with a bispyridyl-based quinolinate ligand: the anion-controlled tunable structural and magnetic properties
Authors: Yuan Guozan , Shan Weilong , Liu Bin , Rong Lulu , Zhang Liyan , Zhang Hui , Wei Xianwen
Published: April 2014

Three anion-controlled Mn(ii) coordination polymers were assembled from a bispyridyl-based quinolinate ligand.
Absorption of caffeine in fermented Pu-er tea is inhibited in mice
Authors: Huang Ye-wei , Xu Huan-huan , Wang Su-min , Zhao Yi , Huang Yu-min , Li Run-bo , Wang Xuan-jun , Hao Shu-mei , Sheng Jun
Published: April 2014

Caffeine is present in a number of dietary sources.
Dimerization hot spots in the structure of human Hsp90
Authors: Rastelli Giulio
Published: April 2014

Molecular dynamics and dimerization free energy analyses performed on the human Hsp90 dimer highlight dimerization hot spots and potential allosteric binding sites.
Recent advances in synthesis of bacterial rare sugar building blocks and their applications
Authors: Emmadi Madhu , Kulkarni Suvarn S.
Published: April 2014

This Highlight describes recent advances in the synthesis of the bacterial deoxy amino hexopyranoside building blocks and their application in constructing various biologically important bacterial O-glycans.
Aryl ethynyl anthraquinones: a useful platform for targeting telomeric G-quadruplex structures
Authors: Percivalle Claudia , Sissi Claudia , Greco Maria Laura , Musetti Caterina , Mariani Angelica , Artese Anna , Costa Giosuè , Perrore Maria Lucia , Alcaro Stefano , Freccero Mauro
Published: April 2014

2,7-Diaryl ethynyl anthraquinones have been synthesized by Sonogashira cross-coupling and evaluated as telomeric G-quadruplex ligands, with good G-quadruplex/duplex selectivity.
Phosphate esters and anhydrides – recent strategies targeting nature's favoured modifications
Authors: Jessen Henning J. , Ahmed Nisar , Hofer Alexandre
Published: April 2014

This perspective highlights some recently developed phosphorylation methodologies focusing on a three-step procedure using P(iii) chemistry (P-amidite coupling, oxidation, deprotection) that allows for the iterative homologation of nucleotides.
Catalytic fluorination of unactivated C(sp3)–H bonds
Authors: Ma Jun-An , Li Shen
Published: April 2014

This Highlight discusses the most recent advances in catalytic fluorination of benzylic, allylic, and aliphatic unactivated C(sp3)–H bonds.
Three novel d7/d10 metal complexes with N-heterocyclic ligand of 2,6-bis(3-pyrazolyl)pyridine: synthesis, structure, surface photovoltage spectroscopy and photocatalytic activity
Authors: Hou Ya Nan , Wang Zhi Nan , Bai Feng Ying , Guan Qing Lin , Wang Xuan , Zhang Rui , Xing Yong Heng
Published: April 2014

We synthesized three novel d7/d10 metal complexes with 2,6-bis(3-pyrazolyl)pyridine and studied their surface photovoltage spectra and photocatalytic activities.
Facile preparation of porous polymeric composite monoliths with superior performances in oil–water separation – a low-molecular mass gelators-based gel emulsion approach
Authors: Chen Xiangli , Liu Lingling , Liu Kaiqiang , Miao Qing , Fang Yu
Published: April 2014

Porous polymeric monoliths with superior oil–water separation properties were prepared by using LMMG-based gel-emulsions as templates.
Graphene-based composite supercapacitor electrodes with diethylene glycol as inter-layer spacer
Authors: Yu Yu , Sun Yongbin , Cao Changyan , Yang Shuliang , Liu Hua , Li Ping , Huang Peipei , Song Weiguo
Published: April 2014

Diethylene-glycol/graphene nano-composites were produced by a simple mild solvothermal method, in which diethylene glycol was grafted onto the surfaces of reduced graphene oxides (RGO) as an inter-layer spacer to prevent the aggregation of graphene single sheets, and wet the RGO as well, resulting in good supercapacitor performance and durability.
Interfacing a heteropolytungstate complex and gelatin through a coacervation process: design of bionanocomposite films as novel electrocatalysts
Authors: Khadro Basma , Baroudi Imane , Goncalves Anne-Marie , Berini Bruno , Pegot Bruce , Nouar Farid , Ha Le Thi Ngoc , Ribot François , Gervais Christel , Carn Florent , Cadot Emmanuel , Mousty Christine , Simonnet-Jégat Corine , Steunou Nathalie
Published: April 2014

Novel modified electrodes exhibit excellent electrocatalytic performance for nitrite detection.
Li4Ti5O12-based anode materials with low working potentials, high rate capabilities and high cyclability for high-power lithium-ion batteries: a synergistic effect of doping, incorporating a conductive phase and reducing the particle size
Authors: Lin Chunfu , Fan Xiaoyong , Xin Yuelong , Cheng Fuquan , Lai Man On , Zhou Henghui , Lu Li
Published: April 2014

Fe2+/Cr3+ doped LTO/MWCNT composites were made by combining doping, compositing and particle-size reduction, and exhibit improved electrochemical performances.
Template-directed proton conduction pathways in a coordination framework
Authors: Inukai Munehiro , Horike Satoshi , Chen Wenqian , Umeyama Daiki , Itakura Tomoya , Kitagawa Susumu
Published: April 2014

Template cations in a coordination framework provide proton conduction pathways with thermal stability.
Multiple phases in the ε-VPO4O–LiVPO4O–Li2VPO4O system: a combined solid state electrochemistry and diffraction structural study
Authors: Bianchini M. , Ateba-Mba J. M. , Dagault P. , Bogdan E. , Carlier D. , Suard E. , Masquelier C. , Croguennec L.
Published: April 2014

Polyanionic materials attract great interest in the field of Li-ion battery research thanks to the wide range of possible available compositions, resulting in a great amount of different properties.
Graphene quantum dots conjugated albumin nanoparticles for targeted drug delivery and imaging of pancreatic cancer
Authors: Nigam Preeti , Waghmode Shobha , Louis Michelle , Wangnoo Shishanka , Chavan Pooja , Sarkar Dhiman
Published: April 2014

Pancreatic cancer is considered to be the deadliest of all cancers due to its poor prognosis and resistance to conventional therapies.
Dextran-coated fluorapatite nanorods doped with lanthanides in labelling and directing osteogenic differentiation of bone marrow mesenchymal stem cells
Authors: Zeng Haifeng , Li Xiyu , Xie Fang , Teng Li , Chen Haifeng
Published: April 2014

A novel approach for labelling and tracking BMSCs in bone tissue engineering by using dextran-coated fluorapatite nanorods doped with lanthanides.
Mussel-inspired polydopamine coating as a versatile platform for synthesizing polystyrene/Ag nanocomposite particles with enhanced antibacterial activities
Authors: Cong Ying , Xia Tian , Zou Miao , Li Zhenni , Peng Bo , Guo Dingzong , Deng Ziwei
Published: April 2014

A mussel-inspired polydopamine coating-assisted electroless Ag metallization procedure was presented to prepare PS/Ag nanocomposite particles with enhanced antibacterial activities.
Quantum dot conjugated S. cerevisiae as smart nanotoxicity indicators for screening the toxicity of nanomaterials
Authors: Chouhan Raghuraj S. , Qureshi Anjum , Niazi Javed H.
Published: April 2014

Quantum dot conjugatedS. cerevisiaeas smart nanotoxicity indicators for screening the toxicity of nanomaterials.
Improved opportunistic feedback with multiuser diversity for wireless systems with finite queue
Authors: Li Hang , Guo Qinghua , Huang Defeng David
Published: April 2014

A contention‐based opportunistic feedback protocol has been proposed in the literature, to achieve multiuser diversity for the downlink transmission of a multiuser wireless system, with the assumption that the incoming data for the active users are infinitely backlogged. However, this assumption is not valid if the authors consider the finite‐length queuing effect in practical systems. By taking not only the channel states, but also the queuing states into account, the authors propose an improved opportunistic feedback protocol with multiuser diversity, and analyse its performance with adaptive modulation and coding. Additionally, instead of solving a system of equations directly, a simple iterative method is proposed to obtain the stationary distribution of the system, where the system behaviour is modelled by a two‐dimensional finite‐state Markov chain. Numerical results demonstrate that the authors proposed protocol is superior to the protocol in the literature in terms of the average throughput, the average spectral efficiency and the average packet delay, when considering the queuing dynamics.
Use of matroid theory to construct a class of good binary linear codes
Authors: Wu Guangfu , Wang Lin , Truong Trieu-Kien
Published: April 2014

It is still an open challenge in coding theory how to design a systematic linear (n, k) − code C over GF(2) with maximal minimum distance d. In this study, based on matroid theory (MT), a limited class of good systematic binary linear codes (n, k, d) is constructed, where n = 2k − 1 + · · · + 2k − δ and d = 2k − 2 + · · · + 2k − δ − 1 for k ≥ 4, 1 ≤ δ < k. These codes are well known as special cases of codes constructed by Solomon and Stiffler (SS) back in 1960s. Furthermore, a new shortening method is presented. By shortening the optimal codes, we can design new kinds of good systematic binary linear codes with parameters n = 2k − 1 + · · · + 2k − δ − 3u and d = 2k − 2 + · · · + 2k − δ − 1 − 2u for 2 ≤ u ≤ 4, 2 ≤ δ < k. The advantage of MT over the original SS construction is that it has an advantage in yielding generator matrix on systematic form. In addition, the dual code C⊥ with relative high rate and optimal minimum distance can be obtained easily in this study.
Application of compressive sensing to limited feedback strategy in large‐scale multiple‐input single‐output cellular networks
Authors: Zhang Zhiyu , Teh Kah Chan , Hung Li Kwok
Published: April 2014

A novel limited feedback strategy based on a compressive sensing technique is proposed for the downlink large‐scale multiple‐input single‐output (MISO) system. The effectiveness of transmit beamformers relies on the feedback quality of channel state information (CSI). The instantaneous CSI is compressed and sent back to the base station (BS) by receivers. An efficient recovery algorithm is applied at the BS in the presence of measurement noise and feedback link noise. The proposed feedback strategy can provide the BS with much more precise CSI as compared with some conventional vector quantisation schemes. The proposed scheme also has lower‐computational complexity. Furthermore, the authors derive a tight lower bound on the user sum rate, assuming that zero‐forcing beamforming is applied at the BS, and that active users are semi‐orthogonal to each other. Numerical results show that the proposed compressive sensing‐based limited feedback scheme yields better performance gain than the conventional channel quantisation approaches.
Investigation of the effect of an increased supervisory signal power in a high‐loss loopback monitoring system
Authors: Nahas Mousaab M. , Blow Keith J.
Published: April 2014

We present experimental results for the effect of an increased supervisory signal power in a high‐loss loopback supervisory system in an optically amplified wavelength division multiplexing (WDM) transmission line. The study focuses on the investigation of increasing the input power for the supervisory signal and the effect on the co‐propagating WDM data signals using different channel spacing. This investigation is useful for determining the power limitation of the supervisory signal if extra power is needed to improve the monitoring. The study also shows the effect of spacing on the quality of the supervisory signal itself because of interaction with adjacent data signals.
Anomalous large electrical capacitance of planar microstructures with vanadium dioxide films near the insulator-metal phase transition
Authors: Aliev V. Sh. , Bortnikov S. G. , Badmaeva I. A.
Published: April 2014

The temperature dependence of electrical capacitance of planar microstructures with vanadium dioxide (VO2) film near the insulator-metal phase transition has been investigated at the frequency of 1 MHz. Electrical capacitance measurements of the microstructures were performed by the technique based on the using of a two-terminal resistor-capacitor module simulating the VO2 layer behavior at the insulator-metal phase transition. At temperatures 325–342 K, the anomalous increase in microstructures capacitance was observed. Calculation of electric field in the microstructure showed that VO2 relative permittivity (ε) reaches ∼108 at the percolation threshold. The high value of ε can be explained by the fractal nature of the interface between metal and insulator clusters formed near the insulator-metal phase transition.
Novel insight into the hydrogen absorption mechanism at the Pd(110) surface
Authors: Ohno Satoshi , Wilde Markus , Fukutani Katsuyuki
Published: April 2014

The microscopic mechanism of low-temperature (80 K < T < 160 K) hydrogen (H) ingress into the H2 (<2.66 × 10−3 Pa) exposed Pd(110) surface is explored by H depth profiling with 15N nuclear reaction analysis (NRA) and thermal desorption spectroscopy (TDS) with isotope (H, D) labeled surface hydrogen. NRA and TDS reveal two types of absorbed hydrogen states of distinctly different depth distributions. Between 80 K and ∼145 K a near-surface hydride phase evolving as the TDS α1 feature at 160 K forms, which initially extends only several nanometers into depth. On the other hand, a bulk-absorbed hydrogen state develops between 80 K and ∼160 K which gives rise to a characteristic α3 TDS feature above 190 K. These two absorbed states are populated at spatially separated surface entrance channels. The near-surface hydride is populated through rapid penetration at minority sites (presumably defects) while the bulk-absorbed state forms at regular terraces with much lower probability per site. In both cases, absorption of gas phase hydrogen transfers pre-adsorbed hydrogen atoms below the surface and replaces them at the chemisorption sites by post-dosed hydrogen in a process that requires much less activation energy (<100 meV) than monatomic diffusion of chemisorbed H atoms into subsurface sites. This small energy barrier suggests that the rate-determining step of the absorption process is either H2 dissociation on the H-saturated Pd surface or a concerted penetration mechanism, where excess H atoms weakly bound to energetically less favorable adsorption sites stabilize themselves in the chemisorption wells while pre-chemisorbed H atoms simultaneously transit into the subsurface. The peculiarity of absorption at regular Pd(110) terraces in comparison to Pd(111) and Pd(100) is discussed.
Design for high-power, single-lobe, grating-surface-emitting quantum cascade lasers enabled by plasmon-enhanced absorption of antisymmetric modes
Authors: Sigler C. , Kirch J. D. , Earles T. , Mawst L. J. , Yu Z. , Botez D.
Published: April 2014

Resonant coupling of the transverse-magnetic polarized (guided) optical mode of a quantum-cascade laser (QCL) to the antisymmetric surface-plasmon modes of 2nd-order distributed-feedback (DFB) metal/semiconductor gratings results in strong antisymmetric-mode absorption. In turn, lasing in the symmetric mode, that is, surface emission in a single-lobe far-field beam pattern, is strongly favored over controllable ranges in grating duty cycle and tooth height. By using core-region characteristics of a published 4.6 μm-emitting QCL, grating-coupled surface-emitting (SE) QCLs are analyzed and optimized for highly efficient single-lobe operation. For infinite-length devices, it is found that when the antisymmetric mode is resonantly absorbed, the symmetric mode has negligible absorption loss (∼0.1 cm−1) while still being efficiently outcoupled, through the substrate, by the DFB grating. For finite-length devices, 2nd-order distributed Bragg reflector (DBR) gratings are used on both sides of the DFB grating to prevent uncontrolled reflections from cleaved facets. Equations for the threshold-current density and the differential quantum efficiency of SE DFB/DBR QCLs are derived. For 7 mm-long, 8.0 μm-wide, 4.6 μm-emitting devices, with an Ag/InP grating of ∼39% duty cycle, and ∼0.22 μm tooth height, threshold currents as low as 0.45 A are projected. Based on experimentally obtained internal efficiency values from high-performance QCLs, slope efficiencies as high as 3.4 W/A are projected; thus, offering a solution for watt-range, single-lobe CW operation from SE, mid-infrared QCLs.
Hypercrosslinked polystyrene networks: An atomistic molecular dynamics simulation combined with a mapping/reverse mapping procedure
Authors: Lazutin A. A. , Glagolev M. K. , Vasilevskaya V. V. , Khokhlov A. R.
Published: April 2014

An algorithm involving classical molecular dynamics simulations with mapping and reverse mapping procedure is here suggested to simulate the crosslinking of the polystyrene dissolved in dichloroethane by monochlorodimethyl ether. The algorithm comprises consecutive stages: molecular dynamics atomistic simulation of a polystyrene solution, the mapping of atomistic structure onto coarse-grained model, the crosslink formation, the reverse mapping, and finally relaxation of the structure dissolved in dichloroethane and in dry state. The calculated values of the specific volume and the elastic modulus are in reasonable quantitative correspondence with experimental data.
Spin orbit splitting of the photon induced Fano resonance in an oscillating graphene electrostatic barrier
Authors: Biswas R. , Sinha C.
Published: April 2014

We investigate theoretically the effect of a time dependent oscillating potential on the transport property of the Dirac Fermion through a monolayer graphene electrostatic barrier under the influence of the Rashba spin orbit interaction. The time dependent problem is solved in the frame work of the non-perturbative Floquet approach. It is noted that the dynamic condition of the barrier may be controlled by tuning the Rashba parameter. Introduction of the spin orbit interaction causes splitting of the Fano resonance (FR), a characteristic feature in photon assisted tunneling. The separation between the spin split FR's gives an indirect measure of the fine structure of the quasi-hole bound state inside the barrier. The present findings on the Rashba splitting of the FR and its external control by tuning the oscillating field parameters might have potential for applications in spintronic devices, especially in the spin field effect transistors. The spin polarization of different Floquet sidebands is found to be quite sensitive to the spin-pseudospin interaction.
Interfacial stress balances in structured continua and free surface flows in ferrofluids
Authors: Chaves Arlex , Rinaldi Carlos
Published: April 2014

Interfacial linear and internal angular momentum balances are obtained for a structured continuum and for the special case of a ferrofluid, a suspension of magnetic nanoparticles in a Newtonian fluid. The interfacial balance equations account for the effects of surface tension and surface tension gradient, magnetic surface excess forces, antisymmetric stresses, and couple stresses in driving interfacial flows in ferrofluids. Application of the interfacial balance equations is illustrated by obtaining analytical expressions for the translational and spin velocity profiles in a thin film of ferrofluid on an infinite flat plate when a rotating magnetic field is applied with axis of rotation parallel to the ferrofluid/air interface. The cases of zero and non-zero spin viscosity are considered for small applied magnetic field amplitude. Expressions for the maximum translational velocity, slope of the translational velocity profile at the ferrofluid/air interface, and volumetric flow rate are obtained and their use to test the relevance of spin viscosity and couple stresses in the flow situation under consideration is discussed.
Bond length and electric current oscillation of long linear carbon chains: Density functional theory, MpB model, and quantum spin transport studies
Authors: Oeiras R. Y. , da Silva E. Z.
Published: April 2014

Carbon linear atomic chains attached to graphene have experimentally been produced. Motivated by these results, we study the nature of the carbon bonds in these nanowires and how it affects their electrical properties. In the present study we investigate chains with different numbers of atoms and we observe that nanowires with odd number of atoms present a distinct behavior than the ones with even numbers. Using graphene nanoribbons as leads, we identify differences in the quantum transport of the chains with the consequence that even and odd numbered chains have low and high electrical conduction, respectively. We also noted a dependence of current with the wire size. We study this unexpected behavior using a combination of first principles calculations and simple models based on chemical bond theory. From our studies, the electrons of carbon nanowires present a quasi-free electron behavior and this explains qualitatively the high electrical conduction and the bond lengths with unexpected values for the case of odd nanowires. Our study also allows the understanding of the electric conduction dependence with the number of atoms and their parity in the chain. In the case of odd number chains a proposed π-bond (MpB) model describes unsaturated carbons that introduce a mobile π-bond that changes dramatically the structure and transport properties of these wires. Our results indicate that the nature of bonds plays the main role in the oscillation of quantum electrical conduction for chains with even and odd number of atoms and also that nanowires bonded to graphene nanoribbons behave as a quasi-free electron system, suggesting that this behavior is general and it could also remain if the chains are bonded to other materials.
Effect of charge patterns along a solid-state nanopore on polyelectrolyte translocation
Authors: Katkar H. H. , Muthukumar M.
Published: April 2014

We investigate the effectiveness of charge patterns along a nanopore on translocation dynamics of a flexible polyelectrolyte. We perform a three dimensional Langevin dynamics simulation of a uniformly charged flexible polyelectrolyte translocating under uniform external electric field through a solid-state nanopore. We maintain the total charge along the pore to be constant, while varying its distribution by placing alternate charged and uncharged sections of different lengths along the pore length. Longest average translocation time is observed for a pattern corresponding to an optimum section length, with a major delay in the translocation time during the pore ejection stage. This optimum section length is independent of lengths of polyelectrolyte and pore within the range studied. A theory based on the Fokker-Planck formalism is found to successfully describe the observed trends with reasonable quantitative agreement.
The shortest-graph method for calculation of the pair-correlation function in crystalline systems
Authors: Yurchenko Stanislav O.
Published: April 2014

A new method for approximate calculation of the pair correlation function g(r) is proposed for crystalline systems of identical particles with isotropic interactions. The main idea of the method is to account for the relative delocalization of each node in g(r) by using only the shortest lattice graph between the given points, thus neglecting smaller contributions from other (non-shortest) graphs. By employing the Lennard-Jones and Yukawa crystalline systems as representative examples, it is shown that the proposed approach yields very good agreement with the results of molecular dynamics simulations up to the melting line. The approach can be useful in approximating the structure of simple crystals (in particular, of crystalline colloids and plasma crystals), and can also be generalized for systems with anisotropic interactions.
Layering transitions and solvation forces in an asymmetrically confined fluid
Authors: Stewart M. C. , Evans R.
Published: April 2014

We consider a simple fluid confined between two parallel walls (substrates), separated by a distance L. The walls exert competing surface fields so that one wall is attractive and may be completely wet by liquid (it is solvophilic) while the other is solvophobic. Such asymmetric confinement is sometimes termed a “Janus Interface.” The second wall is: (i) purely repulsive and therefore completely dry (contact angle θ = 180°) or (ii) weakly attractive and partially dry (θ is typically in the range 160–170°). At low temperatures, but above the bulk triple point, we find using classical density functional theory (DFT) that the fluid is highly structured in the liquid part of the density profile. In case (i), a sequence of layering transitions occurs: as L is increased at fixed chemical potential μ close to bulk gas–liquid coexistence μco, new layers of liquid-like density develop discontinuously. In contrast to confinement between identical walls, the solvation force is repulsive for all wall separations and jumps discontinuously at each layering transition and the excess grand potential exhibits many metastable minima as a function of the adsorption. For a fixed temperature T = 0.56TC, where TC is the bulk critical temperature, we determine the transition lines in the L, μ plane. In case (ii), we do not find layering transitions and the solvation force oscillates about zero. We discuss how our mean-field DFT results might be altered by including effects of fluctuations and comment on how the phenomenology we have revealed might be relevant for experimental and simulation studies of water confined between hydrophilic and hydrophobic substrates, emphasizing it is important to distinguish between cases (i) and (ii).
Dynamically-tunable colloidal band-pass and band-gap filters
Authors: Tahir Mukarram A. , Nori Franco , Yellen Benjamin B.
Published: April 2014

We theoretically study particle motion on a periodic array of positive and negative magnetization domains having non-equal widths driven by a multi-frequency magnetic field input signal. Colloidal particles move across the substrate with positive, zero, or negative time-averaged velocity depending on the frequency ratio, the phase difference, and the ratio of the external field strength to the substrate magnetization. Simulations show that particles of a certain size range can either be transported or locally trapped, thereby providing a mechanism for implementing tunable colloidal band-pass and colloidal band-gap filters.
Properties of gravitationally equilibrated Yukawa systems—A molecular dynamics study
Authors: Charan Harish , Ganesh Rajaraman , Joy Ashwin
Published: April 2014

Using 2D Molecular Dynamics simulation, the equilibrium and dynamical properties of a gravitationally equilibrated Yukawa liquid are investigated. We observe that due to asymmetry introduced in one direction by gravity, several interesting features arise. For example, for a given value of coupling parameter Γ, screening parameter κ, and according to a chosen value of gravitational force g (say in y-direction), the system is seen to exhibit super-, sub- or normal diffusion. Interestingly, x-averaged density profiles, unlike a barotropic fluid, acquires sharp, free surface with scale free linear y-dependence. As can be expected for a system with macroscopic gradients, self-diffusion calculated from Green-Kubo’s formalism does not agree with that obtained from Einstein-Smoluchowski diffusion. A 2D angular-radial pair correlation function g(r, θ) clearly indicates asymmetric features induced by gravity. We observe that due to compression in y-direction, though in liquid state for all values of gravity considered, the transverse mode is found to predominant as compared to the longitudinal mode, leading to a novel Anisotropic Solid-like Yukawa liquid.
Generation of a multi-qubit W entangled state through spatially separated semiconductor quantum-dot-molecules in cavity-quantum electrodynamics arrays
Authors: Liu Siping , Yu Rong , Li Jiahua , Wu Ying
Published: April 2014

Generating entangled states attract tremendous interest as the most vivid manifestation of nonlocality of quantum mechanics and also for emerging applications in quantum information processing (QIP). Here, we propose theoretically a scheme for the deterministic generation of a three-qubit W sate with three semiconductor quantum-dot-molecules (QDMs) trapped in spatially separated cavities connected by optical fibers. The proposed scheme takes full advantage of the voltage-controlled tunnelling effects in QDMs, which induces the quantum coherence and further controls the generation of the W entangled state. The influences of the system parameters and various decoherence processes including spontaneous decay and photon leakage on the fidelity of the W state are discussed in details. Numerical results indicate that our scheme is not only robust against these decoherence factors but also insensitive to the deviation of the system parameters from the ideal conditions. Furthermore, the present scheme can be directly extended to realize an N-qubit W state. Also, this scheme can be generically transferred to other physical systems, including circuit quantum electrodynamics and photonic crystal cavities. The results obtained here may be useful in real experiments for realizing QIP in a solid-state platform.
Asymmetric electroresistance of cluster glass state in manganites
Authors: Lourembam James , Ding Junfeng , Bera Ashok , Lin Weinan , Wu Tom
Published: April 2014

We report the electrostatic modulation of transport in strained Pr0.65(Ca0.75Sr0.25)0.35MnO3 thin films grown on SrTiO3 by gating with ionic liquid in electric double layer transistors (EDLT). In such manganite films with strong phase separation, a cluster glass magnetic state emerges at low temperatures with a spin freezing temperature of about 99 K, which is accompanied by the reentrant insulating state with high resistance below 30 K. In the EDLT, we observe bipolar and asymmetric modulation of the channel resistance, as well as an enhanced electroresistance up to 200% at positive gate bias. Our results provide insights on the carrier-density-dependent correlated electron physics of cluster glass systems.
Thermoelectric transport of Se-rich Ag2Se in normal phases and phase transitions
Authors: Mi Wenlong , Qiu Pengfei , Zhang Tiansong , Lv Yanhong , Shi Xun , Chen Lidong
Published: April 2014

Small amount of Se atoms are used to tune the carrier concentrations (nH) and electrical transport in Ag2Se. Significant enhancements in power factor and thermoelectric figure of merit (zT) are observed in the compositions of Ag2Se1.06 and Ag2Se1.08. The excessive Se atoms do not change the intrinsically electron-conducting character in Ag2Se. The detailed analysis reveals the experiment optimum carrier concentration in Ag2Se is around 5 × 1018 cm−3. We also investigate the temperature of maximum zT and the thermoelectric transport during the first order phase transitions using the recently developed measurement system.
Manipulation of electronic and magnetic properties of M2C (M = Hf, Nb, Sc, Ta, Ti, V, Zr) monolayer by applying mechanical strains
Authors: Zhao Shijun , Kang Wei , Xue Jianming
Published: April 2014

Tuning the electronic and magnetic properties of a material through strain engineering is an effective strategy to enhance the performance of electronic and spintronic devices. In this paper, first-principles calculations based on density functional theory are carried out to investigate the electronic and magnetic properties of M2C(M = Hf, Nb, Sc, Ta, Ti, V, Zr, known as MXenes) subjected to biaxial symmetric mechanical strains. At the strain-free state, all these MXenes exhibit no spontaneous magnetism except for Ti2C and Zr2C which show a magnetic moment of 1.92 and 1.25 μB/unit, respectively. As the tensile strain increases, the magnetic moments of MXenes are greatly enhanced and a transition from nonmagnetism to ferromagnetism is observed for those nonmagnetic MXenes at zero strains. The most distinct transition is found in Hf2C, in which the magnetic moment is elevated to 1.5 μB/unit at a strain of 1.80%. We further show that the magnetic properties of Hf2C are attributed to the band shift mainly composed of Hf(5d) states.
Improvement of electroluminescence performance by integration of ZnO nanowires and single-crystalline films on ZnO/GaN heterojunction
Authors: Shi Zhifeng , Zhang Yuantao , Cui Xijun , Wu Bin , Zhuang Shiwei , Yang Fan , Yang Xiaotian , Zhang Baolin , Du Guotong
Published: April 2014

Heterojunction light-emitting diodes based on n-ZnO nanowires/ZnO single-crystalline films/p-GaN structure have been demonstrated for an improved electroluminescence performance. A highly efficient ultraviolet emission was observed under forward bias. Compared with conventional n-ZnO/p-GaN structure, high internal quantum efficiency and light extraction efficiency were simultaneously considered in the proposed diode. In addition, the diode can work continuously for ∼10 h with only a slight degradation in harsh environments, indicating its good reliability and application prospect in the future. This route opens possibilities for the development of advanced nanoscale devices in which the advantages of ZnO single-crystalline films and nanostructures can be integrated together.
Virtual edge illumination and one dimensional beam tracking for absorption, refraction, and scattering retrieval
Authors: Vittoria Fabio A. , Endrizzi Marco , Diemoz Paul C. , Wagner Ulrich H. , Rau Christoph , Robinson Ian K. , Olivo Alessandro
Published: April 2014

We propose two different approaches to retrieve x-ray absorption, refraction, and scattering signals using a one dimensional scan and a high resolution detector. The first method can be easily implemented in existing procedures developed for edge illumination to retrieve absorption and refraction signals, giving comparable image quality while reducing exposure time and delivered dose. The second method tracks the variations of the beam intensity profile on the detector through a multi-Gaussian interpolation, allowing the additional retrieval of the scattering signal.
Suppression of angiogenesis by atmospheric pressure plasma in human aortic endothelial cells
Authors: Gweon Bomi , Kim Hyeonyu , Kim Kijung , Kim Mina , Shim Eunyoung , Kim Sunja , Choe Wonho , Shin Jennifer H.
Published: April 2014

Atmospheric pressure plasma (APP) has been recognized as a promising tool for cancer therapy based on its ability to remove cancer cells by causing apoptosis and necrosis. However, the effect of APP on the neighboring tissues of tumors remains unknown. Moreover, the role of APP on the vessels near tumors could be very important, because once a tumor becomes vascularized, the potential for metastasis can increase dramatically. We show in the present study that APP can induce cell cycle arrest in endothelial cells and further suppress the angiogenesis process. These results strongly support the use of APP in cancer treatment.