bluuebunny/crossref_metadata_2025 huggingface dataset:
Trimethylamine and trimethylamine N-oxide are supplementary energy sources for a marine heterotrophic bacterium: implications for marine carbon and nitrogen cycling
Authors: Lidbury Ian D E A , Murrell J Colin , Chen Yin
Published: August 2014

Bacteria of the marine Roseobacter clade are characterised by their ability to utilise a wide range of organic and inorganic compounds to support growth. Trimethylamine (TMA) and trimethylamine N-oxide (TMAO) are methylated amines (MA) and form part of the dissolved organic nitrogen pool, the second largest source of nitrogen after N2 gas, in the oceans. We investigated if the marine heterotrophic bacterium, Ruegeria pomeroyi DSS-3, could utilise TMA and TMAO as a supplementary energy source and whether this trait had any beneficial effect on growth. In R. pomeroyi, catabolism of TMA and TMAO resulted in the production of intracellular ATP which in turn helped to enhance growth rate and growth yield as well as enhancing cell survival during prolonged energy starvation. Furthermore, the simultaneous use of two different exogenous energy sources led to a greater enhancement of chemoorganoheterotrophic growth. The use of TMA and TMAO primarily as an energy source resulted in the remineralisation of nitrogen in the form of ammonium, which could cross feed into another bacterium. This study provides greater insight into the microbial metabolism of MAs in the marine environment and how it may affect both nutrient flow within marine surface waters and the flux of these climatically important compounds into the atmosphere.
Strong effects of genetic and lifestyle factors on biomarker variation and use of personalized cutoffs
Authors: Enroth Stefan , Johansson Åsa , Enroth Sofia Bosdotter , Gyllensten Ulf
Published: August 2014

Ideal biomarkers used for disease diagnosis should display deviating levels in affected individuals only and be robust to factors unrelated to the disease. Here we show the impact of genetic, clinical and lifestyle factors on circulating levels of 92 protein biomarkers for cancer and inflammation, using a population-based cohort of 1,005 individuals. For 75% of the biomarkers, the levels are significantly heritable and genome-wide association studies identifies 16 novel loci and replicate 2 previously known loci with strong effects on one or several of the biomarkers with P-values down to 4.4 × 10−58. Integrative analysis attributes as much as 56.3% of the observed variance to non-disease factors. We propose that information on the biomarker-specific profile of major genetic, clinical and lifestyle factors should be used to establish personalized clinical cutoffs, and that this would increase the sensitivity of using biomarkers for prediction of clinical end points.
Expression of Nicotinamide Phosphoribosyltransferase-Influenced Genes Predicts Recurrence-Free Survival in Lung and Breast Cancers
Authors: Zhou Tong , Wang Ting , Garcia Joe G. N.
Published: August 2014

Nicotinamide phosphoribosyltransferase (NAMPT) is a rate-limiting enzyme in the salvage pathway of nicotinamide adenine dinucleotide biosynthesis. NAMPT protein is a secreted plasma biomarker in inflammation and in cancer. The NAMPT enzymatic inhibitor, FK866, acts as an inducer of apoptosis and is a cancer therapeutic candidate, however, little is known regarding the influence of NAMPT on cancer biological mechanisms or on the prognosis of human cancers. We interrogated known microarray data sets to define NAMPT knockdown-influenced gene expression to demonstrate that reduced NAMPT expression strongly dysregulates cancer biology signaling pathways. Comparisons of gene expression datasets of four cancer types generated a N39 molecular signature exhibiting consistent dysregulated expression in multiple cancer tissues. The N39 signature provides a significant and independent prognostic tool of human recurrence-free survival in lung and breast cancers. Despite the absence of clear elucidation of molecular mechanisms, this study validates NAMPT as a novel “oncogene” with a central role in carcinogenesis. Furthermore, the N39 signature provides a potentially useful tool for prediction of recurrence-free survival in lung and breast cancer and validates NAMPT as a novel and effective therapeutic target in cancer.
Investigating Leggett-Garg inequality for a two level system under decoherence in a non-Markovian dephasing environment
Authors: Chen Po-Wen , Ali Md. Manirul
Published: August 2014

Leggett-Garg inequalities (LGI) test the correlations of a single system measured at different times. Violation of LGI implies either the absence of a realistic description of the system or the impossibility of measuring the system without disturbing it. We investigate the violation of the Leggett-Garg inequality for a two level system under decoherence in a non-Markovian dephasing environment. We discuss the non-Markovian dynamics of the violation of LGI at zero temperature and also at finite temperature for different structured environments. An enhanced quantum coherence is shown through the violation of Leggett-Garg inequality in the strong non-Markovian regime of the environment.
Molecular phenotypic profiling of a Saccharomyces cerevisiae strain at the single-cell level
Authors: Schmidt A. Mareike , Fagerer Stephan R. , Jefimovs Konstantins , Buettner Florian , Marro Christian , Siringil Erdem C. , Boehlen Karl L. , Pabst Martin , Ibáñez Alfredo J.
Published: August 2014

Studying cell-to-cell heterogeneity requires techniques which robustly deliver reproducible results with single-cell sensitivity.
Silver-catalyzed cyclization of 2-pyridyl alkynyl carbinols with isocyanides: divergent synthesis of indolizines and pyrroles
Authors: Meng Xianyu , Liao Peiqiu , Liu Jianquan , Bi Xihe
Published: August 2014

Divergent syntheses of indolizines and 2,4-disubstituted pyrroles by the silver-catalyzed cyclization of 2-pyridyl alkynyl carbinols with isocyanides are reported.
The impact of ionic liquid fluorinated moieties on their thermophysical properties and aqueous phase behaviour
Authors: Neves Catarina M. S. S. , Kurnia Kiki A. , Shimizu Karina , Marrucho Isabel M. , Rebelo Luís Paulo N. , Coutinho João A. P. , Freire Mara G. , Canongia Lopes José N.
Published: August 2014

The presence of fluorinated alkyl chains in ionic liquids is quite relevant regarding their thermophysical properties and aqueous phase behaviour.
Fine-tuning solid-state luminescence in NPIs (1,8-naphthalimides): impact of the molecular environment and cumulative interactions
Authors: Mukherjee Sanjoy , Thilagar Pakkirisamy
Published: August 2014

A series of solid-state emissive NPIs (1,8-naphthalimides) are reported and their solution and solid-state emissive properties are correlated with their solid-state packing interactions.
Comparative study of n-dodecyl tetraethylene monoether lyotropic liquid crystals incorporated with graphene and graphene oxide
Authors: Wang Lin , Xin Xia , Yang Mengzhou , Ma Xin , Feng Zhenyu , Chen Rui , Shen Jinglin , Yuan Shiling
Published: August 2014

Graphene incorporated into the hydrophobic layer of C12E4 LLC while GO incorporated into the hydrophilic layer of C12E4 LLC.
Effect of the LHCII pigment–protein complex aggregation on photovoltaic properties of sensitized TiO2 solar cells
Authors: Yang Yiqun , Jankowiak Ryszard , Lin Chen , Pawlak Krzysztof , Reus Michael , Holzwarth Alfred R. , Li Jun
Published: August 2014

Chl–Chl charge transfer states formed in LHCII aggregates are observed to enhance the photocurrent generation in LHCII sensitized solar cell.
The interaction of oxygen with the surface of CeO2–TiO2mixed systems: an example of fully reversible surface-to-molecule electron transfer
Authors: Gionco Chiara , Giamello Elio , Mino Lorenzo , Paganini Maria Cristina
Published: August 2014

CeO2–TiO2mixed oxides showed an unusual and fully reversible interaction with molecular oxygen similar to that of natural and synthetic oxygen carriers.
Simultaneous glucose sensing and biohydrogen evolution from direct photoelectrocatalytic glucose oxidation on robust Cu2O–TiO2 electrodes
Authors: Devadoss Anitha , Sudhagar P. , Ravidhas C. , Hishinuma Ryota , Terashima Chiaki , Nakata Kazuya , Kondo Takeshi , Shitanda Isao , Yuasa Makoto , Fujishima Akira
Published: August 2014

An efficient solar-driven biofuel hydrogen production from direct photoelectrocatalytic oxidation of glucose on a robust Cu2O–TiO2 photoelectrode was demonstrated.
Dually functional, N-doped porous graphene foams as counter electrodes for dye-sensitized solar cells
Authors: Song Long , Luo Qiang , Zhao Fei , Li Yang , Lin Hong , Qu Liangti , Zhang Zhipan
Published: August 2014

Nitrogen-doped porous graphene foams as counter electrodes work effectively with both iodide-based and sulfide-based electrolytes in dye-sensitized solar cells.
Multifunctional MOFs through CO2fixation: a metamagnetic kagome lattice with uniaxial zero thermal expansion and reversible guest sorption
Authors: Keene Tony D. , Murphy Michael J. , Price Jason R. , Sciortino Natasha F. , Southon Peter D. , Kepert Cameron J.
Published: August 2014

The properties of atmospheric CO2fixation, metamagnetism, reversible guest adsorption and zero thermal expansion have been combined in a single robust MOF, [Cu3(bpac)3(CO3)2](ClO4)2·H2O (1·H2O).
A smartphone controlled handheld microfluidic liquid handling system
Authors: Li Baichen , Li Lin , Guan Allan , Dong Quan , Ruan Kangcheng , Hu Ronggui , Li Zhenyu
Published: August 2014

A smartphone-controlled microfluidic liquid handling system capable of performing all the liquid handling steps of a sandwich immunoassay without any human intervention.
Oligomeric state affects oxygen dissociation and diguanylate cyclase activity of globin coupled sensors
Authors: Burns Justin L. , Douglas Deer D. , Weinert Emily E.
Published: August 2014

Globin coupled sensors exist as a mixture of oligomeric states, which affect both enzyme catalysis and oxygen binding.
Radiosynthesis and in vivo evaluation of a novel σ1 selective PET ligand
Authors: Jin Hongjun , Fan Jinda , Zhang Xiang , Li Junfeng , Flores Hubert P. , Perlmutter Joel S. , Parsons Stanley M. , Tu Zhude
Published: August 2014

The σ1 receptor is an important target for CNS disorders.
Adamantane amine derivatives as dual acting NMDA receptor and voltage-gated calcium channel inhibitors for neuroprotection
Authors: Kadernani Yakub E. , Zindo Frank T. , Kapp Erika , Malan Sarel F. , Joubert Jacques
Published: August 2014

A series of adamantane-derived compounds, structurally similar to NGP1-01, were synthesised and showed significant dual NMDA receptor and VGCC inhibitory activities.
3,5-Diamino-1,2,4-triazoles as a novel scaffold for potent, reversible LSD1 (KDM1A) inhibitors
Authors: Kutz Craig J. , Holshouser Steven L. , Marrow Ethan A. , Woster Patrick M.
Published: August 2014

Compounds 6 and 7 represent the first reversible LSD1 inhibitors with minimal cytotoxicity in vitro.
Active guests in the MoS2/MoSe2 host lattice: efficient hydrogen evolution using few-layer alloys of MoS2(1−x)Se2x
Authors: Kiran Vankayala , Mukherjee Debdyuti , Jenjeti Ramesh Naidu , Sampath Srinivasan
Published: August 2014

Alloys are better than the individual elements: tunable electroactivity of few-layer MoS2(1−x)Se2x phases.
Hollow spherical gold nanoparticle superstructures with tunable diameters and visible to near-infrared extinction
Authors: Zhang Chen , Zhou Yong , Merg Andrea , Song Chengyi , Schatz George C. , Rosi Nathaniel L.
Published: August 2014

Hollow spherical gold nanoparticle superstructures with tunable diameters and near-infrared extinction are prepared using straightforward peptide-based one-pot syntheses.
Dispersion RAFT polymerization: comparison between the monofunctional and bifunctional macromolecular RAFT agents
Authors: Gao Chengqiang , Li Shentong , Li Quanlong , Shi Pengfei , Shah Sayyar Ali , Zhang Wangqing
Published: August 2014

The dispersion RAFT polymerizations mediated with monofunctional and bifunctional macro-RAFT agents were comparatively studied, in which different block copolymer morphologies were detected.
Separation of binary solvent mixtures with solvent resistant nanofiltration membranes part B: process modeling
Authors: Li Jiandong , Wang Miaomiao , Huang Yucui , Luo Beibei , Zhang Yuan , Yuan Qipeng
Published: August 2014

This part B of a two paper series develops an improved model derived from the classical solution-diffusion model, specifically for solvent separation process in SRNF.
Bifunctional gold–manganese oxide nanocomposites: benign electrocatalysts toward water oxidation and oxygen reduction
Authors: Rahaman Hasimur , Barman Koushik , Jasimuddin Sk , Ghosh Sujit Kumar
Published: August 2014

Gold–manganese oxide nanocomposites exhibit efficient electrocatalytic activity toward water oxidation and oxygen reduction at a low overpotential and under neutral pH conditions.
Effects of linear amphiphilicity on membrane interactions of C-terminal thrombin peptides
Authors: Singh Shalini , Papareddy Praveen , Kalle Martina , Schmidtchen Artur , Malmsten Martin
Published: August 2014

Highly amphiphilic WFF25 forms aggregates in solution and at membranes. The terminal W/F stretch provides membrane selectivity for WFF25. Pronounced LTA and LPS interactions influence bactericidal effects.
Porous peony-like α-Fe2O3 hierarchical micro/nanostructures: synthesis, characterization and its lithium storage properties
Authors: Yang Tao , Liu Yangai , Huang Zhaohui , Yang Qian , Chen Yongbo , Hu Meiling , Guan Ming , Fang Minghao
Published: August 2014

Hierarchical peony-like FeCO3 micro-flowers were selectively synthesized via a facile template-free hydrothermal process. Porous α-Fe2O3 derived from FeCO3 maintained the original size and morphology of FeCO3. The excellent lithium storage properties of porous α-Fe2O3 micro-flowers were examined.
AlCl3 and liquid Al assisted extraction of Nd from NaCl–KCl melts via intermittent galvanostatic electrolysis
Authors: Li Xing , Yan Yong-De , Zhang Mi-Lin , Xue Yun , Tang Hao , Ji De-Bin , Zhang Zhi-Jian
Published: August 2014

A comparison of the cyclic voltammograms obtained on the W (dotted line) and liquid Al (solid line) electrodes in a NaCl–KCl–NdCl3 (2 wt%) melt. Temperature: 1003 K, scan rate: 0.1 V s−1.
Triflic acid promoted fries rearrangement of C-3 vinyl/isopropenyl-azetidin-2-ones: single-pot synthesis of C-3 functionalized-2-aryl-2,3-dihydro-quinoline-4(1H)-ones
Authors: Mehra Vishu , Singh Parvesh , Bisetty Krishna , Kumar Vipan
Published: August 2014

Single-pot synthesis of C-3 functionalized-2-aryl-2,3-dihydro-quinoline-4(1H)-ones with stability profile validation using density functional theory (DFT) calculations.
A facile route for preparation of monodisperse nanoparticles of one-dimensional Fe(ii)-4-amino-1,2,4-triazole coordination polymers with hysteretic spin-crossover near room temperature
Authors: Chen Meng-Ya , Chen Xuan-Rong , Ning Wei-Hua , Ren Xiao-Ming
Published: August 2014

Monodisperse nanoparticles of one-dimensional Fe(II)-4-amino-1,2,4-triazole coordination polymers show hysteretic spin-crossover near room temperature.
“Combustion always produces carbon dioxide and water”: a discussion of university chemistry students' use of rules in place of principles
Authors: Robertson Amy D. , Shaffer Peter S.
Published: August 2014

On the basis of responses to written questions administered to more than one thousand introductory chemistry students, we claim that students often rotely apply memorized combustion rules instead of reasoning based on explanatory models for what happens at the molecular level during chemical reactions. In particular, many students argue that combustion produces carbon dioxide and/or water, even when the reactants do not contain hydrogen or carbon, an answer that is inconsistent with the principle of atom conservation. Our study also corroborates the finding that students frequently say that oxygen is “necessary for” or “used in” combustion reactions without connecting this reasoning to conservation principles, suggesting that this likewise may be a rotely applied, memorized rule.
A facile synthesis of a novel mesoporous Ge@C sphere anode with stable and high capacity for lithium ion batteries
Authors: Liu Mingxian , Ma Xiaomei , Gan Lihua , Xu Zijie , Zhu Dazhang , Chen Longwu
Published: August 2014

A facial synthesis of mesoporous Ge@C spheres as a stable and high capacity anode for lithium ion batteries is described.
Weak intermolecular interactions promote blue luminescence of protonated 2,2′-dipyridylamine salts
Authors: Chernyshev Alexander N. , Morozov Dmitry , Mutanen Jarkko , Kukushkin Vadim Yu , Groenhof Gerrit , Haukka Matti
Published: August 2014

In this work we demonstrate that protonation and π-stacking can be exploited to convert non-luminescent 2,2′-dipyridylamine into blue-emitting derivatives.
Modelling of electromagnetic field distribution for optimising electrode configurations in liver MR‐based electrical impedance tomography
Authors: Oh Tong In , Chauhan Munish , Sajib Saurav , Kim Ji Eun , Jeong Woo Chul , Wi Hun , Kim Hyung Joong , Kwon Oh , Woo Eung Je
Published: August 2014

In‐vivo electromagnetic field distributions of biological systems can be imaged from the measured magnetic flux density of magnetic resonance‐based electrical impedance tomography (MREIT), which was induced by the externally injected current through a pair of electrodes. Since the electromagnetic field is affected by the injected current and electrical conductivity of biological tissues, the electrode type and position are important factors for determining the voltage and current density distribution. Using a three‐dimensional finite element model, the current pathway and electric field distribution to optimise the electrode configurations in liver MREIT are estimated.
Position centroid rendezvous and centroid formation of multiple unicycle agents
Authors: Xie Wenjing , Ma Baoli
Published: August 2014

This work investigates the position centroid rendezvous/formation problems of multiple unicycle agents for the first time. By constructing a new output, the unicycle model is converted to canonical normal form via feedback linearisation approach. Then, we propose the centroid rendezvous and the centroid formation control laws, respectively, guaranteeing that all the agents globally meet at the common initial centroid location and the desired geometric pattern centred at the initial centroid. The proposed control laws are distributed, smooth and time‐varying, ensuring the internal orientation states and the velocity inputs convergent to some fixed values and zero, respectively. All the results are proved under the communication scenarios of fixed directed balanced graph with a spanning tree. Simulation results verify the effectiveness and the robustness of the proposed control schemes.
Fast and low‐frequency adaptation in neural network control
Authors: Pan Yongping , Gao Qin , Yu Haoyong
Published: August 2014

In adaptive neural network (NN) control, fast adaptation through high‐gain learning rates can cause high‐frequency oscillations in control response resulting in system instability. This study presents a simple adaptive NN with proportional derivative (PD) control strategy to achieve fast and low‐frequency adaptation for a class of uncertain non‐linear systems. Variable‐gain PD control without the knowledge of plant bounds is proposed to semi‐globally stabilise the plant, so that NN approximation is applicable. A low‐pass filter‐based modification is applied to the adaptive law to filter out high‐frequency content, so that tracking performance can be safely improved by the increase of learning rates. The novelties of this study with respect to adaptive NN control are as follows: (i) semi‐global practical asymptotic tracking can be achieved by a simple adjustment of control parameters; and (ii) fast and low‐frequency adaptation can be obtained via high‐gain learning rates under guaranteed system stability. Simulation studies have demonstrated that the proposed approach can outperform its non‐filtering counterpart in terms of tracking accuracy, energy cost and control smoothness.
Local image descriptor based on spectral embedding
Authors: Yan Pu , Tang Jun , Zhu Ming , Liang Dong
Published: August 2014

This study presents a local image descriptor based on spectral embedding. Specifically, the spectra of line graph are used to represent image edges, corners and edge points with big curvature. The authors theoretically analyse and experimentally verify that the spectra of line graph are robust to noise and are invariant to rotation and linear intensity changes. Based on such a fact, some local image descriptors are constructed using the spectra of line graph. Comparative experiments demonstrate the effectiveness of the proposed descriptor and its superiority to some state‐of‐the‐art descriptors under image rotation, image blur, viewpoint change, illumination change, JPEG compression and noise.
Pulse compression security enhancement as an electronic protection technique by exploiting a block cipher output as phase‐code
Authors: Sanandaji Nader , Soleimani Mohammad
Published: August 2014

In this study, the exploitation of a block cipher output as phase‐code for pulse compression in a radar system is introduced. This method is as an effective electronic protection technique against some electronic intelligence‐based electronic attacks. Security enhancement of the mentioned scheme is discussed and some autocorrelation properties of it are investigated. Probabilities of false alarm and detection in case of using a block cipher generated phase‐code are also studied. A new method for countering the effects of repeater jammers and digital radio frequency memories is also proposed which is based on block cipher encryption key update. This new method tries to implement a low probability of identification radar. All of the mentioned subjects are investigated by mathematical equations and simulation verifications.
Prolonged antimicrobial activity of unique sandwich‐structured silver nanocomposites
Authors: Dong Yaohua , Liu Tao , Song Xiao , Dong Lihua , Guo Zhangwei , Shen Yuanyuan
Published: August 2014

In this reported work, silver (Ag) nanocomposites (NCs) with three different structures were prepared to confirm that structure has significant influence on the antibacterial properties. Ag nanoparticles (NPs) were prepared by the following three methods: first, by deposition of Ag on the surface of silica‐polydopamine spheres by reducing Ag cations (NC1), secondly, by encapsulation of Ag NPs in mesoporous SiO2 with a core–shell structure (NC2) and thirdly, Ag nanocrystals were both decorated on the surface of SiO2 and incorporated into its mesoporous structure (NC3). The key to the successful synthesis of the aforementioned NCs was polydopamine (PD) having the unique reductive ability and powerful adhesive capability. The antibacterial activities of NC1, NC2 and NC3 were evaluated through bacterial growth curves assay carried out on Vibrio natriegens (V. natriegens) strain, a Gram‐negative bacterium, supported by observations from transmission electron microscopy. The results demonstrated that in the first three days, the effect of NC1 was more intense on V. natriegens compared with NC2; however, the next seven days revealed the opposite result. Therefore NC3 exhibited the most effective antimicrobial treatments for ten days.
2D potential measurements by applying automatic beam adjustment system to heavy ion beam probe diagnostic on the Large Helical Device
Authors: Shimizu A. , Ido T. , Kurachi M. , Makino R. , Nishiura M. , Kato S. , Nishizawa A. , Hamada Y.
Published: August 2014

Two-dimensional potential profiles in the Large Helical Device (LHD) were measured with heavy ion beam probe (HIBP). To measure the two-dimensional profile, the probe beam energy has to be changed. However, this task is not easy, because the beam transport line of LHD-HIBP system is very long (∼20 m), and the required beam adjustment consumes much time. To reduce the probe beam energy adjustment time, an automatic beam adjustment system has been developed. Using this system, required time to change the probe beam energy is dramatically reduced, such that two-dimensional potential profiles were able to be successfully measured with HIBP by changing the probe beam energy shot to shot.
Critical properties of the Ziff, Gulari, and Barshad (ZGB) model with inert sites
Authors: Hoenicke G. L. , de Andrade M. F. , Figueiredo W.
Published: August 2014

We study the model proposed by Ziff, Gulari, and Barshad to mimic the oxidation of carbon monoxide (CO) in the presence of fixed impurities distributed over the catalytic surface. Our focus is on the continuous phase transition between the active phase, where occurs the production of carbon dioxide (CO2), and the inactive phase, where all the non inert sites become filled with oxygen molecules. We employ Monte Carlo simulations to calculate the different ratios between moments of the order parameter at the critical point, as well as, we determine the critical exponents β and ν⊥ as a function of the concentration of impurities. We show that the presence of impurities over the catalytic surface changes the critical behavior of the system. The critical exponents depend on the concentration of impurities and the model does not belong to the directed percolation universality class.
Simultaneous measurement of refractive-index and thickness for optical materials by laser feedback interferometry
Authors: Xu Ling , Zhang Shulian , Tan Yidong , Sun Liqun
Published: August 2014

The refractive index measurement by ordinary interferometers cannot avoid the air disturbances in the optical path. A novel approach is presented in this paper based on the Nd:YAG microchip laser feedback interferometry (MLFI) with 1064 nm wavelength. For eliminating the air flow and electric-heating influence the heterodyne modulation and quasi-common path in the MLFI are used. The simultaneous measurement with high accuracy of the refractive index and thickness is realized. The measurement results for three kinds of materials are presented including N-SF57 glass with high index up to 1.81057. The measurement uncertainty of refractive index is better than 0.00002 and of thickness is better than 0.0006 mm.
Solute-solvent cavity and bridge functions. I. Varying size of the solute
Authors: Vyalov I. , Chuev G. , Georgi N.
Published: August 2014

In this work we present the results of the extensive molecular simulations of solute-solvent cavity and bridge functions. The mixtures of Lennard-Jones solvent with Lennard-Jones solute at infinite dilution are considered for different solute-solvent size ratios—up to 4:1. The Percus-Yevick and hypernetted chain closures deviate substantially from simulation results in the investigated temperature and density ranges. We also find that the behavior of the indirect and cavity correlation functions is non-monotonous within the hard-core region, but the latter can be successfully approximated by mean-field theory if the solute-solvent interaction energy is divided into repulsive and attractive contribution, according to Weeks-Chandler-Andersen theory. Furthermore, in spite of the non-monotonous behavior of logarithm of the cavity function and the indirect correlation function, their difference, i.e., the bridge function remains constant within the hard-core region. Such behavior of the bridge and indirect correlation functions at small distances and for small values of indirect correlation function is well known from the Duh-Haymet plots, where the non-unique relationship results in loops of the bridge function vs. indirect correlation function graphs. We show that the same pathological behavior appears also when distance is small and indirect correlation function is large. We further show that the unique functional behavior of the bridge function can be established when bridge is represented as a function of the renormalized, repulsive indirect correlation function.
Rare-earth neutral metal injection into an electron beam ion trap plasma
Authors: Magee E. W. , Beiersdorfer P. , Brown G. V. , Hell N.
Published: August 2014

We have designed and implemented a neutral metal vapor injector on the SuperEBIT high-energy electron beam ion trap at the Lawrence Livermore National Laboratory. A horizontally directed vapor of a europium metal is created using a thermal evaporation technique. The metal vapor is then spatially collimated prior to injection into the trap. The source's form and quantity constraints are significantly reduced making plasmas out of metal with vapor pressures ≤10−7 Torr at ≥1000 °C more obtainable. A long pulsed or constant feed metal vapor injection method adds new flexibility by varying the timing of injection and rate of material being introduced into the trap.
Density cumulant functional theory from a unitary transformation: N-representability, three-particle correlation effects, and application to ${\rm O}_4^+$O4+
Authors: Sokolov Alexander Yu. , Schaefer Henry F. , Kutzelnigg Werner
Published: August 2014

A new approach to density cumulant functional theory is developed that derives density cumulant N-representability conditions from an approximate Fock space unitary transformation. We present explicit equations for the third- and fourth-order two-particle cumulant N-representability, as well as the second-order contributions that depend on the connected three-particle density cumulant. These conditions are used to formulate the ODC-13 method and the non-iterative (λ3) correction that employ an incomplete description of the fourth-order two-particle cumulant N-representability and the second-order three-particle correlation effects, respectively. We perform an analysis of the ODC-13 N-representability description for the dissociation of H2 and apply the ODC-13 method and the (λ3) correction to diatomic molecules with multiple bond character and the symmetry-breaking tetraoxygen cation (\documentclass[12pt]{minimal}\begin{document}${\rm O}_4^+$\end{document}O4+). For the \documentclass[12pt]{minimal}\begin{document}${\rm O}_4^+$\end{document}O4+ molecule, the vibrational frequencies of the ODC-13(λ3) method do not exhibit spatial symmetry breaking and are in a good agreement with the recent infrared photodissociation experiment. We report the \documentclass[12pt]{minimal}\begin{document}${\rm O}_4^+$\end{document}O4+ equilibrium structure, harmonic frequencies, and dissociation energy computed using ODC-13(λ3) with a diffuse, core-correlated aug-cc-pCVTZ basis set.
Behavior of supercooled aqueous solutions stemming from hidden liquid–liquid transition in water
Authors: Biddle John W. , Holten Vincent , Anisimov Mikhail A.
Published: August 2014

A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid–liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid–liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H2O-NaCl and H2O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid–liquid transition. We elucidate the non-conserved nature of the order parameter (extent of “reaction” between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.
Alkali vapor pressure modulation on the 100 ms scale in a single-cell vacuum system for cold atom experiments
Authors: Dugrain Vincent , Rosenbusch Peter , Reichel Jakob
Published: August 2014

We describe and characterize a device for alkali vapor pressure modulation on the 100 ms timescale in a single-cell cold atom experiment. Its mechanism is based on optimized heat conduction between a current-modulated alkali dispenser and a heat sink at room temperature. We have studied both the short-term behavior during individual pulses and the long-term pressure evolution in the cell. The device combines fast trap loading and relatively long trap lifetime, enabling high repetition rates in a very simple setup. These features make it particularly suitable for portable atomic sensors.
Optics design for J-TEXT ECE imaging with field curvature adjustment lens
Authors: Zhu Y. , Zhao Z. , Liu W. D. , Xie J. , Hu X. , Muscatello C. M. , Domier C. W. , Luhmann N. C. , Chen M. , Ren X. , Tobias B. J. , Zhuang G. , Yang Z.
Published: August 2014

Significant progress has been made in the imaging and visualization of magnetohydrodynamic and microturbulence phenomena in magnetic fusion plasmas. Of particular importance has been microwave electron cyclotron emission imaging (ECEI) for imaging Te fluctuations. Key to the success of ECEI is a large Gaussian optics system constituting a major portion of the focusing of the microwave radiation from the plasma to the detector array. Both the spatial resolution and observation range are dependent upon the imaging optics system performance. In particular, it is critical that the field curvature on the image plane is reduced to decrease crosstalk between vertical channels. The receiver optics systems for two ECEI on the J-TEXT device have been designed to ameliorate these problems and provide good performance with additional field curvature adjustment lenses with a meniscus shape to correct the aberrations from several spherical surfaces.
Field effect in the quantum Hall regime of a high mobility graphene wire
Authors: Barraud C. , Choi T. , Butti P. , Shorubalko I. , Taniguchi T. , Watanabe K. , Ihn T. , Ensslin K.
Published: August 2014

In graphene-based electronic devices like in transistors, the field effect applied thanks to a gate electrode allows tuning the charge density in the graphene layer and passing continuously from the electron to the hole doped regime across the Dirac point. Homogeneous doping is crucial to understand electrical measurements and for the operation of future graphene-based electronic devices. However, recently theoretical and experimental studies highlighted the role of the electrostatic edge due to fringing electrostatic field lines at the graphene edges [P. Silvestrov and K. Efetov, Phys. Rev. B 77, 155436 (2008); F. T. Vasko and I. V. Zozoulenko, Appl. Phys. Lett. 97, 092115 (2010)]. This effect originates from the particular geometric design of the samples. A direct consequence is a charge accumulation at the graphene edges giving a value for the density, which deviates from the simple picture of a plate capacitor and also varies along the width of the graphene sample. Entering the quantum Hall regime would, in principle, allow probing this accumulation thanks to the extreme sensitivity of this quantum effect to charge density and the charge distribution. Moreover, the presence of an additional and counter-propagating edge channel has been predicted [P. Silvestrov and K. Efetov, Phys. Rev. B 77, 155436 (2008)] giving a fundamental aspect to this technological issue. In this article, we investigate this effect by tuning a high mobility graphene wire into the quantum Hall regime in which charge carriers probe the electrostatic potential at high magnetic field close to the edges. We observe a slight deviation to the linear shift of the quantum Hall plateaus with magnetic field and we study its evolution for different filling factors, which correspond to different probed regions in real space. We discuss the possible origins of this effect including an increase of the charge density towards the edges.
Quantum interference in thermoelectric molecular junctions: A toy model perspective
Authors: Nozaki Daijiro , Avdoshenko Stas M. , Sevinçli Hâldun , Cuniberti Gianaurelio
Published: August 2014

Quantum interference (QI) phenomena between electronic states in molecular circuits offer a new opportunity to design new types of molecular devices such as molecular sensors, interferometers, and thermoelectric devices. Controlling the QI effect is a key challenge for such applications. For the development of single molecular devices employing QI effects, a systematic study of the relationship between electronic structure and the quantum interference is needed. In order to uncover the essential topological requirements for the appearance of QI effects and the relationship between the QI-affected line shape of the transmission spectra and the electronic structures, we consider a homogeneous toy model where all on-site energies are identical and model four types of molecular junctions due to their topological connectivities. We systematically analyze their transmission spectra, density of states, and thermoelectric properties. Even without the degree of freedom for on-site energies an asymmetric Fano peak could be realized in the homogeneous systems with the cyclic configuration. We also calculate the thermoelectric properties of the model systems with and without fluctuation of on-site energies. Even under the fluctuation of the on-site energies, the finite thermoelectrics are preserved for the Fano resonance, thus cyclic configuration is promising for thermoelectric applications. This result also suggests the possibility to detect the cyclic configuration in the homogeneous systems and the presence of the QI features from thermoelectric measurements.
Langmuir probe measurements and mass spectrometry of plasma plumes generated by laser ablation of La0.4Ca0.6MnO3
Authors: Chen Jikun , Lunney James G. , Lippert Thomas , Ojeda-G-P Alejandro , Stender Dieter , Schneider Christof W. , Wokaun Alexander
Published: August 2014

The plasma formed in vacuum by UV nanosecond laser ablation of La0.4Ca0.6MnO3 in the fluence range of 0.8 to 1.9 J cm−2 using both Langmuir probe analysis and energy-resolved mass spectrometry has been studied. Mass spectrometry shows that the main positive ion species are Ca+, Mn+, La+, and LaO+. The Ca+ and Mn+ energy distributions are quite broad and lie in the 0–100 eV region, with the average energies increasing with laser fluence. In contrast, the La+ and LaO+ distributions are strongly peaked around 10 eV. The net time-of-arrival signal derived from the measured positive ion energy distributions is broadly consistent with the positive ion signal measured by the Langmuir probe. We also detected a significant number of O− ions with energies in the range of 0 to 10 eV. The Langmuir probe was also used to measure the temporal variation of the electron density and temperature at 6 cm from the ablation target. In the period when O− ions are found at this position, the plasma conditions are consistent with those required for significant negative oxygen ion formation, as revealed by studies on radio frequency excited oxygen plasma.
Disorder density of states in supported graphene
Authors: Sinha Dhiraj , Lee Ji Ung
Published: August 2014

Transport in graphene is impacted by disorder. Disorder, which can occur on supported graphene, manifests as a significant shift in the Fermi level position from the charge neutrality point (Dirac point) and leads to carrier scattering. Here, we provide a direct measurement of the disorder density of states (DOS). We show that the disorder is extrinsic to graphene and is characterized by a continuum of DOS located at the graphene-substrate interface. A key feature is a Gaussian-like DOS that causes pinning of the Fermi level and the shift in the Dirac point.
Proximity-induced superconductivity in crystalline Cu and Co nanowires and nanogranular Co structures
Authors: Kompaniiets M. , Dobrovolskiy O. V. , Neetzel C. , Begun E. , Porrati F. , Ensinger W. , Huth M.
Published: August 2014

We report an experimental study of proximity effect-induced superconductivity in crystalline Cu and Co nanowires and a nanogranular Co nanowire structure in contact with a superconducting W-based floating electrode (inducer). For electrical resistance measurements up to three pairs of Pt-based voltage leads were attached at different distances beside the inner inducer electrode, thus allowing us to probe the proximity effect over a length of 2–12 μm. Up to 30% resistance drops with respect to the normal-state value have been observed for the crystalline Co and Cu nanowires when sweeping the temperature below Tc of the inducer (5.2 K). By contrast, relative R(T) drops were found to be an order of magnitude smaller for the nanogranular Co nanowire structure. Our analysis of the resistance data shows that the superconducting proximity length in crystalline Cu and Co is about 1 μm at 2.4 K, attesting to a long-range proximity effect in the Co nanowire. Moreover, this long-range proximity effect is insusceptible to magnetic fields up to 11 T, which is indicative of spin-triplet pairing. At the same time, proximity-induced superconductivity in the nanogranular Co nanowire is strongly suppressed due to the dominating Cooper pair scattering caused by its intrinsic microstructure.
Optically imprinted reconfigurable photonic elements in a VO2 nanocomposite
Authors: Jostmeier Thorben , Zimmer Johannes , Karl Helmut , Krenner Hubert J. , Betz Markus
Published: August 2014

We investigate the optical and thermal hysteresis of single-domain vanadium dioxide nanocrystals fabricated by ion beam synthesis in a fused silica matrix. The nanocrystals exhibit a giant hysteresis, which permits to optically generate a long-time stable supercooled metallic phase persistent down to practically room temperature. Spatial patterns of supercooled and insulating nanocrystals feature a large dielectric contrast, in particular, for telecom wavelengths. We utilize this contrast to optically imprint reconfigurable photonic elements comprising diffraction gratings as well as on- and off-axis zone plates. The structures allow for highly repetitive (>104) cycling through the phase transition without structural damage.
Enhanced resonance transmission of acoustic waves based on asymmetric excitation of Lamb waves in phononic crystals with wedges-like structures
Authors: Li Jing , Zeng Qianghua , Liu Zhengyou
Published: August 2014

In this paper, enhanced resonance transmission of acoustic waves with good performance is demonstrated in two-dimensional phononic crystals with wedges-like structures. The enhanced acoustic transmission originates from the excitation of asymmetric Lamb modes. The local resonances in the wedges-like structures play a vital important role in the excitation of asymmetric Lamb modes and promote the strong in-phase coupling of the flexural motions on the upper and lower plates of the liquid cavity, which leads to enhanced resonance transmission with high transmission ratio and narrow full width at half maximum. The enhanced transmission spectra for different liquids filled are also studied. Optimization of the liquid cavity geometry is further performed to improve the performance of the enhanced resonance transmission peaks. The proposed acoustic system has potential applications in tunable filtering and sensing applications.
On the structural-optical properties of Al-containing amorphous Si thin films and the metal-induced crystallization phenomenon
Authors: Zanatta A. R. , Kordesch M. E.
Published: August 2014

Amorphous (a-)Si-based materials always attracted attention of the scientific community, especially after their use in commercial devices like solar cells and thin film transistors in the 1980s. In addition to their technological importance, the study of a-Si-based materials also present some interesting theoretical-practical challenges. Their crystallization as induced by metal species is one example, which is expected to influence the development of electronic-photovoltaic devices. In fact, the amorphous-to-crystalline transformation of the a-SiAl system has been successfully applied to produce solar cells suggesting that further improvements can be achieved. Stimulated by these facts, this work presents a comprehensive study of the a-SiAl system. The samples, with Al contents in the ∼0−15 at. % range, were made in the form of thin films and were characterized by different spectroscopic techniques. The experimental results indicated that: (a) increasing amounts of Al changed both the atomic structure and the optical properties of the samples; (b) thermal annealing induced the crystallization of the samples at temperatures that depend on the Al concentration; and (c) the crystallization process was also influenced by the annealing duration and the structural disorder of the samples. All of these aspects were addressed in view of the existing models of the a-Si crystallization, which were also discussed to some extent. Finally, the ensemble of experimental results suggest an alternative method to produce cost-effective crystalline Si films with tunable structural-optical properties.
Aerodynamic performance and characteristic of vortex structures for Darrieus wind turbine. II. The relationship between vortex structure and aerodynamic performance
Authors: Sun Xiaojing , Wang Ying , An Qimeng , Cao Yang , Wu Guoqing , Huang Diangui
Published: August 2014

In this paper, transient computational fluid dynamics (CFD) simulations of a straight-bladed Darrieus type vertical axis wind turbine were performed by means of an in-house CFD code. The Spalart-Allmaras turbulence model was implemented in the numerical code for the turbulence. Particular emphasis was placed on effect of interaction between vortices and blades on the aerodynamic performance of the simulated turbine at different tip speed and solidity ratios. The obtained results suggested that vortices were shed from previous blade passages and the close encounter of a rotor blade with these vortices can have a considerable impact on power coefficient of the simulated turbine during operation at different tip speed ratios. As a result, possible reasons for the changes in the behavior of this type of turbine due to the variation of tip speed ratio and solidity were proposed.
Measuring the complex admittance of a nearly isolated graphene quantum dot
Authors: Zhang Miao-Lei , Wei Da , Deng Guang-Wei , Li Shu-Xiao , Li Hai-Ou , Cao Gang , Tu Tao , Xiao Ming , Guo Guang-Can , Jiang Hong-Wen , Guo Guo-Ping
Published: August 2014

We measured the radio-frequency reflection spectrum of an on-chip reflection line resonator coupled to a graphene double quantum dot (DQD), which was etched almost isolated from the reservoir and reached the low tunnel rate region. The charge stability diagram of DQD was investigated via dispersive phase and magnitude shift of the resonator with a high quality factor. Its complex admittance and low tunnel rate to the reservoir was also determined from the reflected signal of the on-chip resonator. Our method may provide a non-invasive and sensitive way of charge state readout in isolated quantum dots.
Towards a graphene-based quantum impedance standard
Authors: Kalmbach C.-C. , Schurr J. , Ahlers F. J. , Müller A. , Novikov S. , Lebedeva N. , Satrapinski A.
Published: August 2014

Precision measurements of the quantum Hall resistance with alternating current (ac) in the kHz range were performed on epitaxial graphene in order to assess its suitability as a quantum standard of impedance. The quantum Hall plateaus measured with alternating current were found to be flat within one part in 107. This is much better than for plain GaAs quantum Hall devices and shows that the magnetic-flux-dependent capacitive ac losses of the graphene device are less critical. The observed frequency dependence of about −8 × 10−8/kHz is comparable in absolute value to the positive frequency dependence of plain GaAs devices, but the negative sign is attributed to stray capacitances which we believe can be minimized by a careful design of the graphene device. Further improvements thus may lead to a simpler and more user-friendly quantum standard for both resistance and impedance.