bluuebunny/crossref_metadata_2025 huggingface dataset:
Tunneling spectroscopy of close-spaced dangling-bond pairs in Si(001):H
Authors: Engelund Mads , Zuzak Rafał , Godlewski Szymon , Kolmer Marek , Frederiksen Thomas , García-Lekue Aran , Sánchez-Portal Daniel , Szymonski Marek
Published: September 2015

We present a combined experimental and theoretical study of the electronic properties of close-spaced dangling-bond (DB) pairs in a hydrogen-passivated Si(001):H p-doped surface. Two types of DB pairs are considered, called “cross” and “line” structures. Our scanning tunneling spectroscopy (STS) data show that, although the spectra taken over different DBs in each pair exhibit a remarkable resemblance, they appear shifted by a constant energy that depends on the DB-pair type. This spontaneous asymmetry persists after repeated STS measurements. By comparison with density functional theory (DFT) calculations, we demonstrate that the magnitude of this shift and the relative position of the STS peaks can be explained by distinct charge states for each DB in the pair. We also explain how the charge state is modified by the presence of the scanning tunneling microscopy (STM) tip and the applied bias. Our results indicate that, using the STM tip, it is possible to control the charge state of individual DBs in complex structures, even if they are in close proximity. This observation might have important consequences for the design of electronic circuits and logic gates based on DBs in passivated silicon surfaces.
Decreased bilateral thalamic gray matter volume in first-episode schizophrenia with prominent hallucinatory symptoms: A volumetric MRI study
Authors: Huang Peng , Xi Yibin , Lu Zhong-Lin , Chen Yunchun , Li Xiangrui , Li Weiguo , Zhu Xia , Cui Long-Biao , Tan Qingrong , Liu Wenming , Li Chen , Miao Danmin , Yin Hong
Published: September 2015

Studies comparing gray matter (GM) volume of schizophrenic patients with or without auditory verbal hallucinations (AVHs) to that of normal controls remain controversial. This project aims to investigate changes of GM volumes of drug-naïve schizophrenic patients with and without AVHs. Eighteen first episode schizophrenic (FES) patients with AVHs, 18 FES patients without AVHs and 18 healthy controls were scanned using structural MRI. Voxel-based morphometry (VBM) analysis was conducted to investigate changes of GM volume among the three groups. Patients with and without AVHs exhibited reduced GM volumes relative to normal controls in the left superior temporal gyrus, frontal regions, cerebellum and caudate. Further analysis of the GM of subcortical structures found that patients with AVHs had reduced thalamic volume than healthy controls. No significant difference was found between patients with and without AVHs. Significant correlation was found between the total scores of the Positive and Negative Syndrome Scale and bilateral thalamic volume. ROC analysis of thalamic volumes of the patients with AVHs and normal controls showed that the area under the curve was 0.698 (P = 0.043). The decreased thalamic volumes might serve as a biomarker for discriminating FES AVHs patients from normals.
Determination of hydroquinone based on the formation of Turnbull's blue nanoparticles using resonance Rayleigh scattering
Authors: Yuan Yusheng , Li Chunyan , Zhu Jinghui , Liu Shaopu , Liu Zhongfang , Yang Jidong , Qiao Man , Shi Ying , Duan Ruilin , Hu Xiaoli
Published: September 2015

A novel simple sensitive and inexpensive method based on the formation of Turnbull's blue nanoparticles using resonance Rayleigh scattering has been developed for the determination of hydroquinone (HQ).
Surface engineering for an enhanced photoelectrochemical response of TiO2 nanotube arrays by simple surface air plasma treatment
Authors: Zhang Tingting , Cui Siwen , Yu Bo , Liu Zhilu , Wang Daoai
Published: September 2015

A simple method to improve the photoelectrochemical performance of TiO2 NTs by simple air plasma post-treatment is reported. The photocurrent density and IPCE are 3–4 times higher than that of the pristine TiO2 NTs even after six months.
In situ detection of salicylate in Ocimum basilicum plant leaves via reverse iontophoresis
Authors: González-Sánchez M. I. , Lee P. T. , Guy R. H. , Compton R. G.
Published: September 2015

We report an in situ quantitative method to measure the concentration of salicylates, from intact, living Ocimum basilicum plant leaves. This simple, non-invasive method utilises iontophoresis in combination with cyclic voltammetry at disposable screen-printed electrodes.
Insights into dynamic covalent chemistry at surfaces
Authors: Plas Jan , Waghray Deepali , Adisoejoso Jinne , Ivasenko Oleksandr , Dehaen Wim , De Feyter Steven
Published: September 2015

The potential of surface confined self-assembly to influence the chemical equilibrium of Schiff base formation and bias the yield and distribution of reaction products is explored.
Benzylic C–H trifluoromethylation of phenol derivatives
Authors: Egami Hiromichi , Ide Takafumi , Kawato Yuji , Hamashima Yoshitaka
Published: September 2015

Phenol derivatives were trifluoromethylated using copper/Togni reagent. Reaction in DMF selectively gave benzylic trifluoromethylation products, whereas aromatic trifluoromethylation products were obtained in t-BuOH.
Space science applications for conducting polymer particles: synthetic mimics for cosmic dust and micrometeorites
Authors: Fielding Lee A. , Hillier Jon K. , Burchell Mark J. , Armes Steven P.
Published: September 2015

The design of conducting polymer-based particles as synthetic mimics for understanding the behaviour of micro-meteorites (a.k.a. cosmic dust) is reviewed and the implications for various space science applications is discussed.
Two-step vapor transport deposition of large-size bridge-like Bi2Se3 nanostructures
Authors: Han Manshu , Ma Jiangang , Xu Haiyang , Liu Yichun
Published: September 2015

A “two-step growth” method for obtaining large dimensional bridge-like Bi2Se3 nanostructures was proposed for the first time.
Hydrogenation of Pt/TiO2{101} nanobelts: a driving force for the improvement of methanol catalysis
Authors: Liu Feila , Xiao Peng , Tian Wei Quan , Zhou Ming , Li Yanhong , Cui Xun , Zhang Yunhuai , Zhou Xin
Published: September 2015

Single-crystalline anatase TiO2nanobelts with a dominant surface of the {101} facet were hydrogenated and used as active substrates of platinum for methanol oxidation reaction (MOR).
The importance of hydration and DNA conformation in interpreting infrared spectra of cells and tissues
Authors: Wood Bayden R.
Published: September 2015

The effect of hydration on cells and tissues modifies the DNA conformation leading to dramatic changes in the FTIR spectra, which has important implications in disease diagnosis.
Mechanism of intramolecular transformations of nickel phosphanido hydride complexes
Authors: Latypov Shamil K. , Polyancev Fedor M. , Ganushevich Yulia S. , Miluykov Vasily A. , Sinyashin Oleg G.
Published: September 2015

Intramolecular interconversion of nickel phosphanido hydride complexes ([NiH{P(Ar)(H)}(dtbpe)]) occurred in three steps: first, hydride proton migrates to phosphorus, then P-Aryl moiety rotates around the P–Ni bond and finally the back migration of one proton to Ni.
A Zn(ii) coordination polymer and its photocycloaddition product: syntheses, structures, selective luminescence sensing of iron(iii) ions and selective absorption of dyes
Authors: Hu Fei-long , Shi Yi-Xiang , Chen Huan-Huan , Lang Jian-Ping
Published: September 2015

Nanospheres of a Zn(ii) complex are used to selectively sense iron(iii) ions while its photocycloaddition product can selectively absorb dyes.
High volumetric uptake of ammonia using Cu-MOF-74/Cu-CPO-27
Authors: Katz Michael J. , Howarth Ashlee J. , Moghadam Peyman Z. , DeCoste Jared B. , Snurr Randall Q. , Hupp Joseph T. , Farha Omar K.
Published: September 2015

The MOF Cu-MOF-74/Cu-CPO-27 was identified as a candidate for high-volumetric ammonia uptake due to the high density of Cu sites.
Chronic dosing of a simulated pond ecosystem in indoor aquatic mesocosms: fate and transport of CeO2 nanoparticles
Authors: Tella M. , Auffan M. , Brousset L. , Morel E. , Proux O. , Chanéac C. , Angeletti B. , Pailles C. , Artells E. , Santaella C. , Rose J. , Thiéry A. , Bottero J.-Y.
Published: September 2015

Indoor aquatic mesocosms were designed to mimic pond ecosystems contaminated by a continuous point-source discharge of cerium oxide nanoparticles (CeO2-NPs).
Toxicity of engineered metal oxide nanomaterials mediated by nano–bio–eco–interactions: a review and perspective
Authors: He Xiaojia , Aker Winfred G. , Fu Peter P. , Hwang Huey-Min
Published: September 2015

This is a comprehensive review on the toxicity of metal oxide nanomaterials regarding their environmental interactions at the nano–bio–eco interface.
Wild Roman chamomile extracts and phenolic compounds: enzymatic assays and molecular modelling studies with VEGFR-2 tyrosine kinase
Authors: Guimarães Rafaela , Calhelha Ricardo C. , Froufe Hugo J. C. , Abreu Rui M. V. , Carvalho Ana Maria , Queiroz Maria João, R. P. , Ferreira Isabel C. F. R.
Published: September 2015

Wild Roman chamomile extracts and phenolic compounds showed capacity to inhibit the VEGFR-2 phosphorylation.
The effects of the aqueous extract and residue of Matcha on the antioxidant status and lipid and glucose levels in mice fed a high-fat diet
Authors: Xu Ping , Ying Le , Hong Gaojie , Wang Yuefei
Published: September 2015

Matcha is a kind of powdered green tea produced by grinding with a stone mill.
Phenolic compounds from red wine and coffee are associated with specific intestinal microorganisms in allergic subjects
Authors: Cuervo Adriana , Hevia Arancha , López Patricia , Suárez Ana , Diaz Carmen , Sánchez Borja , Margolles Abelardo , González Sonia
Published: September 2015

The dietary modulation of gut microbiota, suggested to be involved in allergy processes, has recently attracted much interest. Here, we show the association between polyphenol-rich beverages and faecal microbiota in allergic patients.
Brønsted acidity of bio-protic ionic liquids: the acidic scale of [AA]X amino acid ionic liquids
Authors: Zhang Lei , He Ling , Hong Cheng-Bin , Qin Song , Tao Guo-Hong
Published: September 2015

The Brønsted acidity of typical “bio-base” protic ionic liquids, [AA]X amino acid ionic liquids, was systematically studied.
Semi-synthesis and anti-tumor evaluation of novel 25-hydroxyprotopanaxadiol derivatives as apoptosis inducing agents
Authors: Qu Fanzhi , Zhao Chen , Liu Yafei , Cao Jiaqing , Li Wei , Zhao Yuqing
Published: September 2015

Among novel 25-OH-PPD derivatives, compounds 3xt and 9xt exhibited the most potent anti-tumor activities and significantly induced DU145 cell apoptosis.
Effect of anions on the morphology of CdS nanoparticles prepared via thermal decomposition of different cadmium thiourea complexes in a solvent and in the solid state
Authors: Gaur Rama , Jeevanandam Pethaiyan
Published: September 2015

Use of single-molecular precursors with different anions has been demonstrated to be an excellent method to synthesize CdS nanoparticles with different morphologies without using any external capping agent.
Bio-electro degradation of azo-dye in a combined anaerobic–aerobic process along with energy recovery
Authors: Sultana Saima , Khan Mohammad Danish , Sabir Suhail , Gani Khalid M. , Oves Mohammad , Khan Mohammad Zain
Published: September 2015

Complete removal of reactive orange 16 in a microbial fuel cell coupled aerobic post-treatment process along with energy recovery.
Photochemical processes induced by the irradiation of 4-hydroxybenzophenone in different solvents
Authors: Barsotti Francesco , Brigante Marcello , Sarakha Mohamed , Maurino Valter , Minero Claudio , Vione Davide
Published: September 2015

The singlet and triplet excited states of 4-hydroxybenzophenone (4BPOH) undergo deprotonation in the presence of water to produce the anionic ground-state, causing fluorescence quenching and photoactivity inhibition. The same process does not take place in an aprotic solvent such as acetonitrile. In acetonitrile, 4BPOH is fluorescent (interestingly, one of its fluorescence peaks overlaps with peak C of humic substances), it yields singlet oxygen upon irradiation and induces the triplet-sensitised transformation of phenol (with a rate constant of (6.6 ± 0.3) × 107 M−1 s−1 (μ ± σ) between phenol itself and a triplet 4BPOH). The 4BPOH shows an intermediate behaviour in a partially protic solvent such as 2-propanol, where some deprotonation of the excited states is observed. In acetonitrile/2-propanol mixtures (at least up to 50% of 2-propanol) there is also some evidence of alcohol oxidation by the 4BPOH triplet state, while the experimental data are silent concerning such a possibility in pure 2-propanol. Considering that benzophenones are important components of chromophoric dissolved organic matter (CDOM) in surface waters, the present findings could have significance for the photoactivity of the hydrophilic surface layers vs. the hydrophobic cores of CDOM.
Macro-RAFT agent mediated dispersion polymerization: the monomer concentration effect on the morphology of the in situ synthesized block copolymer nano-objects
Authors: Ding Zhonglin , Gao Chengqiang , Wang Shuang , Liu Hui , Zhang Wangqing
Published: September 2015

The great effect of the monomer concentration on the block copolymer morphology under dispersion RAFT polymerization is found and demonstrated.
Interactions of a zwitterionic thiophene-based conjugated polymer with surfactants
Authors: Costa Telma , de Azevedo Diego , Stewart Beverly , Knaapila Matti , Valente Artur J. M. , Kraft Mario , Scherf Ullrich , Burrows Hugh D.
Published: September 2015

Structural organization and photoluminescence properties of zwitterionic conjugated polymer–surfactant assemblies depend on specific and non-specific polymer–surfactant interactions within the aggregate.
Energetic polymeric networks prepared via a solvent- and catalyst-free thermal cycloaddition of azide-bearing polymers with alkynes and hydroxyl-isocyanate addition reactions
Authors: Min Byoung Sun , Jeon Heung Bae , Jeong Tae Uk , Kim Sang Youl
Published: September 2015

The construction of azide-bearing polymeric networks using a dipolarophile and a diisocyanate.
Evaluation of toxicity and biodegradability for cholinium-based deep eutectic solvents
Authors: Juneidi Ibrahim , Hayyan Maan , Hashim Mohd Ali
Published: September 2015

The first study investigating the toxicity of cholinium-based DESs on freshwater fish or fungi and the biodegradability of EAC-based DESs.
Interface induced transition from bipolar resistive switching to unipolar resistive switching in Au/Ti/GaOx/NiOx/ITO structures
Authors: Chu X. L. , Wu Z. P. , Guo D. Y. , An Y. H. , Huang Y. Q. , Guo X. C. , Cui W. , Li P. G. , Li L. H. , Tang W. H.
Published: September 2015

The transition of resistive switching behavior from bipolar to unipolar induced by interface was found and investigated in Au/Ti/GaOx/NiOx/ITO structure.
One-step synthesis of fluorescent silicon quantum dots (Si-QDs) and their application for cell imaging
Authors: Wu Jinzhu , Dai Jun , Shao Yanbin , Sun Yanchun
Published: September 2015

Novel fluorescent silicon quantum dots (Si-QDs) were synthesized by a one-step hydrothermal procedure using (3-aminopropyl)trimethoxysilane (APTES) as a silicon source and sodium ascorbate (SA) as a reducing agent.
Effect of zeolite on SPEEK /zeolite hybrid membrane as electrolyte for microbial fuel cell applications
Authors: Narayanaswamy Venkatesan Prabhu , Dharmalingam Sangeetha
Published: September 2015

A zeolite (H-faujasite) incorporated SPEEK membrane was demonstrated as an effective proton exchange membrane for Microbial Fuel Cell (MFC) application.
A one-pot synthesis of nanostructured mesoporous TiO2 films on graphite felt substrates for fast catalysis
Authors: El-Kacemi S. , Es-Souni Mar. , Habouti S. , Schopf D. , Hamdani M. , Es-Souni M.
Published: September 2015

Crack-free mesoporous anatase films are obtained on graphite felt using a one-pot synthesis from a precursor solution. The films are characterized by high photocatalytic performance in comparison to macro-mesoporous films on silicon substrates.
Nitrogen-doped porous carbon obtained via one-step carbonizing biowaste soybean curd residue for supercapacitor applications
Authors: Ma Guofu , Ran Feitian , Peng Hui , Sun Kanjun , Zhang Zhiguo , Yang Qian , Lei Ziqiang
Published: September 2015

In this work, we present a facile approach to prepare nitrogen-doped porous carbon materials via one-step carbonizing biowaste soybean curd residue (SCR) as the biomass carbon precursor.
Scaffold and cell line based approaches for QSAR studies on anticancer agents
Authors: Satbhaiya Shruti , Chourasia O. P.
Published: September 2015

Importance of 2D QSAR in drug discovery, lower number of descriptors containing models shows best statistical parameters, number of involved scaffolds in models affects the statistical values.
Dynamical heterogeneities and defects in two-dimensional soft colloidal crystals
Authors: van der Meer B. , Qi W. , Sprakel J. , Filion L. , Dijkstra M.
Published: September 2015

We investigate the microscopic origin of dynamical heterogeneities in two-dimensional colloidal crystals and hexatic phases. Our data illustrates how cooperative motions of particles are driven by the formation and diffusion of mobile defects.
Hierarchical nanosheet-based CoMoO4–NiMoO4nanotubes for applications in asymmetric supercapacitors and the oxygen evolution reaction
Authors: Yin Zhuoxun , Chen Yujin , Zhao Yang , Li Chunyan , Zhu Chunling , Zhang Xitian
Published: September 2015

Hierarchical nanosheet-based CoMoO4–NiMoO4nanotubes exhibit superior electrochemical properties for applications in asymmetric supercapacitors and the oxygen evolution reaction.
High thermoelectric performance of Nb-doped SrTiO3 bulk materials with different doping levels
Authors: Zhang Boyu , Wang Jun , Zou Tao , Zhang Shuai , Yaer Xinba , Ding Nan , Liu Chengyan , Miao Lei , Li Yan , Wu Yin
Published: September 2015

Nb-doped SrTiO3 bulk materials with high quality are fabricated using a facile process.
Picosecond dynamics in a millimetre‐wave RTD–MOSFET wavelet generator
Authors: Ohlsson L. , Fay P. , Wernersson L.‐E.
Published: September 2015

The performance of a millimetre‐wave wavelet generator under picosecond‐pulsed trigger operation conditions has been evaluated experimentally. The reactively‐loaded resonant tunnelling diodes metal–oxide‐semiconductor field‐effect‐transistor circuit is shown to generate well‐formed wavelets for control pulse‐lengths down to approximately the free‐running carrier oscillation period. Transient circuit simulations have also been implemented to provide additional insight into the observed circuit dynamics.
Comparative study between two market clearing schemes in wind dominant electricity markets
Authors: Farashbashi‐Astaneh Seyed‐Mostafa , Hu Weihao , Chen Zhe
Published: September 2015

High price volatility and excessive price reduction are introduced as two emerging problems in wind dominant electricity markets. In this study, an agent‐based simulation methodology is employed to investigate the impact of two pricing mechanisms, uniform and pay‐as‐bid, on the mentioned problems. According to the proposed agent‐based approach, electricity market agents (here generation units) learn from their previous bidding experience to obtain maximum financial. A comparative study is then conducted to investigate the impact of mentioned pricing schemes on price volatility and average price level. It is shown that these two pricing mechanisms cause different bidding behaviours for the generation units. This study suggests that this change in market agent behaviour, modifies the overall price volatility and system average price. The results indicate that a pay‐as‐bid pricing mechanism can alleviate policy maker's concerns regarding mentioned emerging problems in power systems with extremely high percentage of wind power penetration. It is also shown that market efficiency is lower under pay‐as‐bid scheme. The validity of the proposed methodology is investigated using IEEE 24‐bus test system with 33 generation units.
Impact of wind power on arbitrage revenue for electricity storage
Authors: Dunbar Anna , Cradden Lucy C. , Wallace Robin , Harrison Gareth P.
Published: September 2015

Electrical energy storage provides a potential solution to the challenge of integrating large amounts of intermittent renewable energy into the electricity system. To make storage commercially viable, its operators will have to aggregate multiple revenue streams across the electricity industry. Arbitrage is recognised as one potential revenue stream. To date, wind power has provided a small contribution toward electricity generation in Great Britain (GB). Gas generators have delivered a significant proportion of total demand. Historic electricity prices reflect this, being driven principally by variations in gas price and daily demand cycles. The study reported here investigates the potential impact of wind power on electricity prices and arbitrage opportunities for energy storage in GB. Results indicate that increased wind power leads to higher price volatility for low electricity prices, but reduced frequency of higher prices which may be detrimental to storage revenue.
Multi‐level dispatch control architecture for power systems with demand‐side resources
Authors: Hu Jianqiang , Cao Jinde , Yong Taiyou
Published: September 2015

Demand‐side resources have considerable potential, which can provide efficient load shedding operations so as to maintain the supply–demand balance together with generating units. This study is concerned with active power dispatch and control problems by considering both generating units and demand‐side resources, where some controllable loads in demand‐side are aggregated under each bus load agent. A multi‐level dispatch control architecture is proposed, which can handle the optimisation and control problems in different time scales. Specifically, an upper layer performs calculation of system's look‐ahead dispatch for generating units and bus load agents, while a middle level computes control actions for multiple load clusters in each bus load agent via a distributed consensus estimation algorithm, and multiple energy management units in the lower layer respond the control instruction issued from the load cluster based on a distributed pinning control algorithm. For the middle and lower layers, participants can communicate with its neighbours via sparse communication networks for the sake of distributed calculation or distributed control, which is more robust than the centralised strategies in terms of dealing with massive amounts of participation units. The simulation results on a modified IEEE 9 bus system show the applicability of the proposed architecture.
Feature‐based surrogates for low‐cost microwave modelling and optimisation
Authors: Koziel Slawomir , Cheng Qingsha S. , Bandler John W.
Published: September 2015

A simple, reliable, and accurate surrogate modelling technique for microwave structures is presented. A hierarchical surrogate model is constructed using response surface approximations (RSAs) of suitable response features with embedded ‘visible’ knowledge. The authors describe and discuss a novel scanning algorithm for capturing these desired response features. They demonstrate that the dependence of the selected features on the designable parameters is much less non‐linear than that of the original responses taken as functions of the design parameters. They illustrate the steps of their algorithm using novel diagrams. They simplify the description of their modelling process by exploiting an operator notation. They discuss relationships between their method and other feature‐based approaches such as shape‐preserving response prediction (SPRP). They provide a wideband microstrip bandstop filter, a fourth‐order ring resonator bandpass filter and a microstrip bandpass filter with open stub inverter examples to demonstrate their approach. Using these examples, they compare their approach with two very different direct RSA methods (kriging and radial basis function) and an SPRP method. The models of all the filter examples are validated using design optimisation.
Global electromagnetic simulations of the outer core of an ASDEX Upgrade L-mode plasma
Authors: Abiteboul J. , Görler T. , Jenko F. , Told D. ,   ASDEX Upgrade Team
Published: September 2015

The outer core of a low confinement discharge performed at the ASDEX Upgrade tokamak is investigated using both global and local nonlinear gyrokinetic simulations. Previous work [Told et al., Phys. Plasmas 20, 122312 (2013)] had shown that local gyrokinetic simulations agree reasonably well with experimental results in terms of transport levels, with minor discrepancies that can be resolved within the uncertainties of the experimental profile. In the present work, the analysis of the same discharge is extended to include global gradient-driven simulations with the GENE code, taking into account the plasma profiles from mid-radius up to close to the separatrix. It is shown that the mean fluxes obtained assuming the local approximation are in general agreement with results from global simulations. Moreover, both types of simulations exhibit large-scale avalanche-like events, both in the ion and electron heat fluxes, with similar basic properties. However, analyzing the statistics of the fluxes reveals that intermittency is more important in the global case. Furthermore, even when averaging over turbulent time scales, radial corrugations in the ion temperature profile are identified in the global simulation. These corrugations are at most of the order of 1%, but correspond to up to 10% variations in the gradient. Thus, while the results on the mean fluxes support the validity of the local approximation, the presence of corrugated structures may pose a challenge for the direct validation of local gyrokinetic simulations against experiments.
Quantum free energy landscapes from ab initio path integral metadynamics: Double proton transfer in the formic acid dimer is concerted but not correlated
Authors: Ivanov Sergei D. , Grant Ian M. , Marx Dominik
Published: September 2015

With the goal of computing quantum free energy landscapes of reactive (bio)chemical systems in multi-dimensional space, we combine the metadynamics technique for sampling potential energy surfaces with the ab initio path integral approach to treating nuclear quantum motion. This unified method is applied to the double proton transfer process in the formic acid dimer (FAD), in order to study the nuclear quantum effects at finite temperatures without imposing a one-dimensional reaction coordinate or reducing the dimensionality. Importantly, the ab initio path integral metadynamics technique allows one to treat the hydrogen bonds and concomitant proton transfers in FAD strictly independently and thus provides direct access to the much discussed issue of whether the double proton transfer proceeds via a stepwise or concerted mechanism. The quantum free energy landscape we compute for this H-bonded molecular complex reveals that the two protons move in a concerted fashion from initial to product state, yet world-line analysis of the quantum correlations demonstrates that the protons are as quantum-uncorrelated at the transition state as they are when close to the equilibrium structure.
Elucidation of reactive wavepackets by two-dimensional resonance Raman spectroscopy
Authors: Guo Zhenkun , Molesky Brian P. , Cheshire Thomas P. , Moran Andrew M.
Published: September 2015

Traditional second-order kinetic theories fail to describe sub-picosecond photochemical reactions when solvation and vibrational dephasing undermine the assumption of equilibrium initial conditions. Four-wave mixing spectroscopies may reveal insights into such non-equilibrium processes but are limited by the single “population time” available in these types of experiments. Here, we use two-dimensional resonance Raman (2DRR) spectroscopy to expose correlations between coherent nuclear motions of the reactant and product in the photodissociation reaction of triiodide. It is shown that the transition of a nuclear wavepacket from the reactant (triiodide) to product (diiodide) states gives rise to a unique pattern of 2DRR resonances. Peaks associated with this coherent reaction mechanism are readily assigned, because they are isolated in particular quadrants of the 2DRR spectrum. A theoretical model in which the chemical reaction is treated as a vibronic coherence transfer transition from triiodide to diiodide reproduces the patterns of 2DRR resonances detected in experiments. These signal components reveal correlation between the nonequilibrium geometry of triiodide and the vibrational coherence frequency of diiodide. The 2DRR signatures of coherent reaction mechanisms established in this work may generalize to studies of ultrafast energy and charge transfer processes.
Nanoscale phase change memory with graphene ribbon electrodes
Authors: Behnam Ashkan , Xiong Feng , Cappelli Andrea , Wang Ning C. , Carrion Enrique A. , Hong Sungduk , Dai Yuan , Lyons Austin S. , Chow Edmond K. , Piccinini Enrico , Jacoboni Carlo , Pop Eric
Published: September 2015

Phase change memory (PCM) devices are known to reduce in power consumption as the bit volume and contact area of their electrodes are scaled down. Here, we demonstrate two types of low-power PCM devices with lateral graphene ribbon electrodes: one in which the graphene is patterned into narrow nanoribbons and the other where the phase change material is patterned into nanoribbons. The sharp graphene “edge” contacts enable switching with threshold voltages as low as ∼3 V, low programming currents (<1 μA SET and <10 μA RESET) and OFF/ON resistance ratios >100. Large-scale fabrication with graphene grown by chemical vapor deposition also enables the study of heterogeneous integration and that of variability for such nanomaterials and devices.
An atomistic vision of the Mass Action Law: Prediction of carbon/oxygen defects in silicon
Authors: Brenet G. , Timerkaeva D. , Sgourou E. N. , Londos C. A. , Caliste D. , Pochet P.
Published: September 2015

We introduce an atomistic description of the kinetic Mass Action Law to predict concentrations of defects and complexes. We demonstrate in this paper that this approach accurately predicts carbon/oxygen related defect concentrations in silicon upon annealing. The model requires binding and migration energies of the impurities and complexes, here obtained from density functional theory (DFT) calculations. Vacancy-oxygen complex kinetics are studied as a model system during both isochronal and isothermal annealing. Results are in good agreement with experimental data, confirming the success of the methodology. More importantly, it gives access to the sequence of chain reactions by which oxygen and carbon related complexes are created in silicon. Beside the case of silicon, the understanding of such intricate reactions is a key to develop point defect engineering strategies to control defects and thus semiconductors properties.
Dynamics of flexible fibers in shear flow
Authors: Słowicka Agnieszka M. , Wajnryb Eligiusz , Ekiel-Jeżewska Maria L.
Published: September 2015

Dynamics of flexible non-Brownian fibers in shear flow at low-Reynolds-number are analyzed numerically for a wide range of the ratios A of the fiber bending force to the viscous drag force. Initially, the fibers are aligned with the flow, and later they move in the plane perpendicular to the flow vorticity. A surprisingly rich spectrum of different modes is observed when the value of A is systematically changed, with sharp transitions between coiled and straightening out modes, period-doubling bifurcations from periodic to migrating solutions, irregular dynamics, and chaos.
Conformational sampling enhancement of replica exchange molecular dynamics simulations using swarm particle intelligence
Authors: Kamberaj Hiqmet
Published: September 2015

In this paper, we present a new method based on swarm particle social intelligence for use in replica exchange molecular dynamics simulations. In this method, the replicas (representing the different system configurations) are allowed communicating with each other through the individual and social knowledge, in additional to considering them as a collection of real particles interacting through the Newtonian forces. The new method is based on the modification of the equations of motion in such way that the replicas are driven towards the global energy minimum. The method was tested for the Lennard-Jones clusters of N = 4,  5, and 6 atoms. Our results showed that the new method is more efficient than the conventional replica exchange method under the same practical conditions. In particular, the new method performed better on optimizing the distribution of the replicas among the thermostats with time and, in addition, ergodic convergence is observed to be faster. We also introduce a weighted histogram analysis method allowing analyzing the data from simulations by combining data from all of the replicas and rigorously removing the inserted bias.
Relating photocurrent, photovoltage, and charge carrier density to the recombination rate in organic photovoltaic cells
Authors: Mullenbach Tyler K. , Holmes Russell J.
Published: September 2015

The power output of an organic photovoltaic cell (OPV) depends on the relationship between device voltage and charge carrier recombination rate. Suppressing recombination until higher voltages allows for increased photocurrent leading to a concomitant increase in power generated. Despite the important role played by recombination in OPVs, its dependence on voltage remains understudied. This is mainly because most techniques used to measure recombination rates are only applicable under open-circuit conditions. In order to address recombination away from open-circuit, a modified charge extraction technique is used to empirically determine the relationship between charge carrier density and device voltage. This relationship, in conjunction with the device photocurrent density-voltage characteristic, is sufficient to connect the recombination rate at open-circuit to any operating voltage.
Temporal and spatial profiles of emission intensities in atmospheric pressure helium plasma jet driven by microsecond pulse: Experiment and simulation
Authors: Wang Ruixue , Zhang Cheng , Shen Yuan , Zhu Weidong , Yan Ping , Shao Tao , Babaeva Natalia Yu. , Naidis George V.
Published: September 2015

A needle-circular electrode structure helium plasma jet driven by microsecond pulsed power is studied. Spatially resolved emission results show that the emission intensity of He(33S1) line decreases monotonically along the axial direction, while those of N2(C3Πu), N2+(B2∑+u), and O(3p5P) reach their maxima at 3 cm, 2.6 cm, and 1.4 cm, respectively. The plasma plume of the four species shows different characteristics: The N2 emission plume travels at a fast speed along the entire plasma jet; the N2+ emission plume is composed of a bright head and relatively weak tail and travels a shorter distance than the N2 emission plume; the He emission plume travels at a slower speed for only a very short distance; propagation of the O emission plume is not observed. Results of calculation of radiation fluxes emitted by positive streamers propagating along helium plasma jets are presented. It is shown, in agreement with the results of the present experiment and with other available experimental data, that the intensities of radiation of N2(C3Πu) molecules and He(33S1) atoms vary with time (along the plasma jet) quite differently. The factors resulting in this difference are discussed.
Integrable equations of the infinite nonlinear Schrödinger equation hierarchy with time variable coefficients
Authors: Kedziora D. J. , Ankiewicz A. , Chowdury A. , Akhmediev N.
Published: September 2015

We present an infinite nonlinear Schrödinger equation hierarchy of integrable equations, together with the recurrence relations defining it. To demonstrate integrability, we present the Lax pairs for the whole hierarchy, specify its Darboux transformations and provide several examples of solutions. These resulting wavefunctions are given in exact analytical form. We then show that the Lax pair and Darboux transformation formalisms still apply in this scheme when the coefficients in the hierarchy depend on the propagation variable (e.g., time). This extension thus allows for the construction of complicated solutions within a greatly diversified domain of generalised nonlinear systems.
Energetics of intrinsic defects in NiO and the consequences for its resistive random access memory performance
Authors: Dawson J. A. , Guo Y. , Robertson J.
Published: September 2015

Energetics for a variety of intrinsic defects in NiO are calculated using state-of-the-art ab initio hybrid density functional theory calculations. At the O-rich limit, Ni vacancies are the lowest cost defect for all Fermi energies within the gap, in agreement with the well-known p-type behaviour of NiO. However, the ability of the metal electrode in a resistive random access memory metal-oxide-metal setup to shift the oxygen chemical potential towards the O-poor limit results in unusual NiO behaviour and O vacancies dominating at lower Fermi energy levels. Calculated band diagrams show that O vacancies in NiO are positively charged at the operating Fermi energy giving it the advantage of not requiring a scavenger metal layer to maximise drift. Ni and O interstitials are generally found to be higher in energy than the respective vacancies suggesting that significant recombination of O vacancies and interstitials does not take place as proposed in some models of switching behaviour.
A semi-annular shock tube for studying cylindrically converging Richtmyer-Meshkov instability
Authors: Luo Xisheng , Ding Juchun , Wang Minghu , Zhai Zhigang , Si Ting
Published: September 2015

A novel semi-annular shock tube is realized by combining the advantageous features of two types of existing facilities for generating cylindrically converging shock waves. A high-speed schlieren photography is used to acquire the variation of shock positions versus the time and the evolution of a single-mode gaseous interface subjected to the cylindrical shock. The first experimental results indicate that the semi-annular configuration brings great convenience for interface formation and flow visualization, and the new facility has great potential for cylindrically converging Richtmyer-Meshkov instability studies.
Abrupt reduction of the critical temperature difference of a thermoacoustic engine by adding water
Authors: Tsuda K. , Ueda Y.
Published: September 2015

The critical temperature difference (ΔTcri) that causes a thermoacoustic spontaneous oscillation is reduced by the presence of water in the working fluid of a thermoacoustic engine. This letter introduces the effects of two design parameters on the reduction of ΔTcri: one is the mass of water added as the working fluid and the other is the characteristic length of the stack, which is the heart of a thermoacoustic engine. The experimental results show that when the mass of added water exceeds the threshold value, ΔTcri decreases abruptly; however, the decreased ΔTcri changes slightly with further increase in the added mass. Moreover, the characteristic length of the stack was found to have little effect on ΔTcri when water is added. These results provide a design guide for a thermoacoustic engine that includes water as the working fluid.
Channel flow of Ellis fluid due to peristalsis
Authors: Ali N. , Abbasi A. , Ahmad I.
Published: September 2015

An analysis is carried out to investigate the peristaltic pumping of a non-Newtonian Ellis fluid in a planar channel. The coupled nonlinear partial differential equations governing the problem are simplified under the widely used assumption of long wavelength and low Reynolds number. A semi- analytical approach is adopted to obtain the expressions for stream function, longitudinal velocity, pressure gradient and pressure rise per wavelength. The important characteristics of the peristaltic motion are explained graphically for several values of the material parameter of the Ellis fluid.
Quantification of salivary cortisol from captive dingoes (Canis dingo) in relation to age, sex, and breeding season: implications for captive management
Authors: Smith Bradley , Flavel Matthew , Simpson Bradley
Published: September 2015

Captive-breeding programs can play a key role in the conservation of threatened species such as the Australian dingo (Canis dingo). It is important to determine whether holding and rearing practices impose stressors that impact negatively on program outcomes and the health and wellbeing of the captive population. Despite evidence that chronic stress has significant welfare implications, our understanding of ‘stress’ in either wild or captive dingoes remains limited. In a first attempt to rectify this, we report salivary cortisol concentrations in juvenile and adult dingoes held in a captive colony. Dingo puppies (n = 8, M = 0.484 ± 0.09 μg dL–1) were found to have higher concentrations than adults (n = 12, M = 0.106 ± 0.031 μg dL–1) (P < 0.0001). Concentrations in adult females (n = 6, M = 0.113 ± 0.030 μg dL–1) and males (n = 6, M = 0.099 ± 0.033 μg dL–1) did not significantly differ (P = 0.4740). Our preliminary findings also suggest that during the annual breeding season, males (but not females) have elevated levels of corticosteroids. Establishing a reference range for cortisol concentrations is vital for researchers and wildlife carers attempting to measure stressors in both captive and wild dingo populations. This study provides useful insight into the influence of time of day, development, and seasonality on cortisol concentrations. Suggestions for future research and implications of routine cortisol evaluation to aid better management practices are also discussed.
Support for linguistic macrofamilies from weighted sequence alignment
Authors: Jäger Gerhard
Published: September 2015

Significance

This article reports findings regarding the automatic classification of Eurasian languages using techniques from computational biology (such as sequence alignment, phylogenetic inference, and bootstrapping). Main results are that there is solid support for the hypothetical linguistic macrofamilies Eurasiatic and Austro-Tai. Unlike comparable previous work, these findings do not depend on manual assessments of etymological facts. This study contributes to ongoing efforts to push the limits of linguistic reconstruction further back in time, and thus to open a window into the pre-Neolithic human past. The methodological approach pursued here can be seen as a statistically informed and automatized version of Joseph Greenberg’s mass lexical comparison, which yielded intriguing results regarding deep genetic relations between languages but has remained controversial among experts.
Environmental and socio-economic impacts of rubber cultivation in the Mekong region: challenges for sustainable land use.
Authors: Häuser I. , Martin K. , Germer J. , He P. , Blagodatskiy S. , Liu HongXi Liu HongXi , Krauss M. , Rajaona A. , Shi Min Shi Min , Langenberger G. , Zhu ChaoDong Zhu ChaoDong , Cotter M. , Stürz S. , Waibel H. , Steinmetz H. , Wieprecht S. , Ahlheim M. , Aenis T. , Cadisch G.
Published: September 2015

More than 90% of the global natural rubber production originates from monoculture plantations in tropical Asia, especially from countries forming the Greater Mekong Subregion (GMS). Rubber cultivation is expected to further increase strongly in the near future, particularly at the expense of natural forests, and is accompanied by various problems and threats to farmers and the environment. Implications on carbon balance and hydrological conditions as well as socio-economic consequences referring to the situation in the GMS are reviewed. Results indicate considerable changes in ecosystem functions and services at different spatial and temporal scales with impacts on carbon stocks and sequestration, water quality and quantity, runoff and soil erosion. The long-term dependency on rubber as a single crop affects the socio-economic conditions and livelihood of the farmers and exposes them to economic and ecological hazards. Solutions for these interrelated problems require the development of alternative land-use systems and safeguarding important ecosystem functions and services on the one hand as well as providing economic viability on the other. Common suggestions include crop diversification and improved plantation management on the farm scale, and alternative land-use strategies including conservation and restoration of forest on the landscape scale. Successful implementation of more sustainable concepts is only feasible within a socio-economic framework, involving farmers and political decision-makers in the conceptualization process and the identification of trade-offs between ecological requirements and economic feasibility.
Expression, purification, and breast cancer cell inhibiting effect of recombinant human lactoferrin C-lobe
Authors: Hu Lulu , Gao Chen-hui , Hong Chao , Zhong Qiao , Dong Hong-Liang , Gao Xiao-Ming
Published: September 2015

Lactoferrin (LTF), a multifunctional glycoprotein of the transferrin family mainly found in exotic secretions in mammals, is an important defense molecule against not only microbial invasion but also tumors. It folds into two globular domains (N- and C-lobes) each containing an iron-binding site. The cationic antimicrobial peptide in N-lobe is known to exert anti-tumor effect via a non-receptor-mediated pathway. However, whether LTF C-lobe also contributes to its anti-tumor activity remains to be investigated. In this study, a human LTF fragment (amino acid residues 343–682) covering the C-lobe was expressed with a histidine tag in E. coli and the purified polypeptide refolded through a series of buffer changing procedure. The resultant recombinant protein caused significant growth arrest of breast carcinoma cells MDA-MB-231 in a dose- and time-dependent manner, evidently via induction of apoptosis of the cell. Our data suggest a positive role for the C-lobe of human LTF in controlling tumors in vitro.
De facto statehood in Eurasia: a political and security phenomenon
Authors: Markedonov Sergey
Published: September 2015

De facto entities (most importantly for this discussion, those in Nagorny Karabakh, South Ossetia, Abkhazia, Transnistria and the alleged People’s Republics in south-eastern Ukraine), if viewed from a formal-legal point of view, do not exist for the international community. However, the “virtual” existence of those states does not prevent them from being real participants in the political and security processes in the post-Soviet space. Many momentous events in Eurasia are connected in some way with developments surrounding these statelets. This article reviews the establishment of de facto states in the context of the demise of the USSR, ethno-political self-determination during this process and the transformation of international law after the end of the Cold War. The article provides a definition and typology of unrecognized states, and explains their similarities and differences. It is argued that the phenomenon of de facto entities cannot be reduced exclusively to the consequences of “frozen conflict”: their domestic dynamics as well as processes of democratization and nation/state-building also need to be considered. Special attention is paid to the importance of Eurasian de facto states for international affairs.