bluuebunny/crossref_metadata_2025 huggingface dataset:
Dissecting the steps of CO2reduction: 1. The interaction of CO and CO2with γ-Al2O3: an in situ FTIR study
Authors: Szanyi János , Kwak Ja Hun
Published: May 2014

The adsorption of CO2on γ-Al2O3produces calcination temperature-dependent surface species.
Acoustic dynamics of supercooled indomethacin probed by Brillouin light scattering
Authors: De Panfilis S. , Pogna E. A. A. , Virga A. , Scopigno T.
Published: May 2014

Brillouin light scattering and broadband picosecond photoacoustic experiments measure the elastic response of indomethacin from the melting point to the glass transition through the undercooled liquid phase.
A survey of diverse earth abundant oxygen evolution electrocatalysts showing enhanced activity from Ni–Fe oxides containing a third metal
Authors: Gerken James B. , Shaner Sarah E. , Massé Robert C. , Porubsky Nicholas J. , Stahl Shannon S.
Published: May 2014

Mixed metal oxides containing Ni, Fe, and a third metal constitute a broad family of highly active water oxidation electrocatalysts.
Molybdenum phosphide as an efficient electrocatalyst for the hydrogen evolution reaction
Authors: Xiao Peng , Sk Mahasin Alam , Thia Larissa , Ge Xiaoming , Lim Rern Jern , Wang Jing-Yuan , Lim Kok Hwa , Wang Xin
Published: May 2014

The phosphorization of molybdenum leads to a good non-noble metal catalyst for the hydrogen evolution reaction in both acidic and alkaline conditions.
Synthesis of β-cyanopropan-1-one derivates by domino reaction
Authors: Dong Hong-Ru , Dong Wang-Jun , Li Rong-Shan , Hu Yi-Ming , Dong Heng-Shan , Xie Zhi-Xiang
Published: May 2014

Polysubstituted β-cyanopropan-1-one was synthesized by the domino nucleophilic addition reaction of four-component Al2O3-catalyzed and low-toxicity reagents.
Highly stereoselective anti-Markovnikov hydrothiolation of alkynes and electron-deficient alkenes by a supported Cu-NHC complex
Authors: Yang Yong , Rioux Robert M.
Published: May 2014

A robust silica-supported Cu-NHC complex catalyzed highly stereoselective anti-Markovnikov hydrothiolation of alkynes or electron-deficient alkenes to construct C–S bonds.
Supramolecular aggregation of yttrium thiocyanate with 4,4′-bipyridine
Authors: Petrosyants Svetlana , Dobrokhotova Zhanna , Ilyukhin Andrey , Novotortsev Vladimir
Published: May 2014

The assemblies [Y(H2O)3EtOH(bpy)(NCS)3]·bpy (1), {(μ-bpy)[Y(H2O)3(NCS)3]2}·3bpy·2(i-PrOH) (2), and [Hbpy]2{(μ-bpy)[Y(H2O)3(NCS)4]2}·bpy (3) were synthesized by the reaction of [Y(H2O)5(NCS)3]·H2O with 4,4′-bipyridine (bpy). The crystal structures of 1–3 consist of interpenetrating rectangular 3D networks.
Blue emitting undecaplatinum clusters
Authors: Chakraborty Indranath , Bhuin Radha Gobinda , Bhat Shridevi , Pradeep T.
Published: May 2014

A blue luminescent 11-atom platinum cluster showing step-like optical features and the absence of plasmon absorption was synthesized.
A hydrophobic disordered peptide spontaneously anchors a covalently bound RNA hairpin to giant lipidic vesicles
Authors: Isaad Alexandra Le Chevalier , Carrara Paolo , Stano Pasquale , Krishnakumar Kollappillil S. , Lafont Dominique , Zamboulis Alexandra , Buchet René , Bouchu Denis , Albrieux Florian , Strazewski Peter
Published: May 2014

Exergonic compartmentation of nucleic acids to liposomes through conjugation with peptides lends experimental support to early evolvable RNA–peptide ‘collaboration’.
Synthesis and properties of fluorous benzoquinones and their application in deprotection of silyl ethers
Authors: Matsubara Hiroshi , Maegawa Takahiko , Kita Yasuaki , Yokoji Takato , Nomoto Akihiro
Published: May 2014

1,4-Benzoquinone derivatives bearing perfluoroalkyl groups were prepared and used as a recyclable catalyst in the selective desilylation of silyl ethers.
Highly stable hybrid selenophene-3,4-ethylenedioxythiophene as electrically conducting and electrochromic polymers
Authors: Lu Baoyang , Zhen Shijie , Zhang Shimin , Xu Jingkun , Zhao Guoqun
Published: May 2014

A family of four novel selenophene–EDOT oligomers were synthesized using Stille coupling and electropolymerized to form highly stable conducting hybrid polymers with excellent electrochromic properties.
A 4-tert-butylcalix[4]arene tetrahydroxamate podand based on the 1-oxypiperidine-2-one (1,2-PIPO−) chelate. Self-assembly into a supramolecular ionophore driven by coordination of tetravalent zirconium or hafnium(iv)
Authors: Jewula Pawel , Chambron Jean-Claude , Penouilh Marie-José , Rousselin Yoann , Meyer Michel
Published: May 2014

K+ is encapsulated by 2 : 2 complexes of tetravalent zirconium or hafnium with the calix[4]arene podand 1H4 carrying four cyclic hydroxamate binding units.
Versatile heavy metals removal via magnetic mesoporous nanocontainers
Authors: Dib S. , Boufatit M. , Chelouaou S. , Sadi-Hassaine F. , Croissant J. , Long J. , Raehm L. , Charnay C. , Durand J.-O.
Published: May 2014

Versatile heavy metal ions removal is performed via iron oxide core mesoporous silica shell nanocontainers functionalized with diethylene triamine pentaacetic acid.
Chiral ionic liquid crystals with a bulky rigid core from renewable camphorsulfonic acid
Authors: Rao Xiaoping , Zhang Jinwen , Zheng Jianqiang , Song Zhanqian , Shang Shibin
Published: May 2014

Renewable chiral d- and l-camphorsulfonic acids were introduced as new building blocks for the design of ionic liquid crystals.
Spin-polarized surface state in Li-doped SnO2(001)
Authors: Din Naseem Ud , Rahman Gul
Published: May 2014

Using LDA + U, we investigate Li-doped rutile SnO2(001) surface.
Highly sensitive turn-on fluorescent detection of cartap via a nonconjugated gold nanoparticle–quantum dot pair mediated by inner filter effect
Authors: Guo Jiajia , Liu Xin , Gao Hanting , Bie Jiaxin , Zhang Yan , Liu Baofeng , Sun Chunyan
Published: May 2014

The well-dispersed AuNPs exhibited a tendency to aggregate when exposed to cartap with positively charged amine groups, which induced an absorption band transition from 522 nm to the long-wavelength band, and restored the IFE-decreased emission of CdTe QDs for cartap detection.
Azobenzene–siloxane hybrids with lamellar structures from bridge-type alkoxysilyl precursors
Authors: Guo Sufang , Chaikittisilp Watcharop , Okubo Tatsuya , Shimojima Atsushi
Published: May 2014

Lamellar azobenzene–siloxane hybrids were prepared by self-directed assembly of three types of precursors where mono-, di- and triethoxysilyl groups are bridged by azobenzene groups with propylene linkers.
Electrocatalytic activity of metalloporphyrins grown in situ on graphene sheets toward oxygen reduction reaction in an alkaline medium
Authors: Jiang Liqing , Li Meng , Lin Lin , Li Yongfeng , He Xingquan , Cui Lili
Published: May 2014

A series of novel non-noble-metal catalysts for ORR, based on metalloporphyrins grown on poly(sodium-p-styrenesulfonate) modified reduced graphene oxide sheets, have been successfully fabricated using an in situ solvothermal synthesis method.
Validation of the 2,3-dihydroxy-propionyl group in selenium speciation by chemical synthesis and LC-MS analyses
Authors: Egressy-Molnár Orsolya , Magyar Anna , Gyepes Attila , Dernovics Mihály
Published: May 2014

Research on 2,3-dihydroxy-propionyl derivatives of selenocysteine has now been facilitated by providing a method for synthesis and clean-up.
Synthesis of cross-linked polymers via multi-component Passerini reaction and their application as efficient photocatalysts
Authors: Lin Wenhai , Sun Tingting , Zheng Min , Xie Zhigang , Huang Yubin , Jing Xiabin
Published: May 2014

Cross-linked polymers containing Ru complexes synthesized via multi-component Passerini reaction were shown to be highly effective and recyclable heterogeneous photocatalysts.
Coumarin based dual switching fluorescent ‘turn-on’ chemosensor for selective detection of Zn2+ and HSO4−: an experimental and theoretical study
Authors: Sarkar Deblina , Pramanik Ajoy Kumar , Mondal Tapan Kumar
Published: May 2014

A coumarin based fluorescence ‘turn-on' chemosensor (HL) for the selective detection of Zn2+ and HSO4¬ has been developed. Emission intensity of HL is enhanced by 27 and 17 fold in presence of Zn2+ and HSO4¬ respectively. Theoretical study interprets the electronic structure and sensing mechanism of HL.
Quinoxaline-functionalized C60 derivatives as electron acceptors in organic solar cells
Authors: Chen Wangqiao , Salim Teddy , Fan Haijun , James Lewis , Lam Yeng Ming , Zhang Qichun
Published: May 2014

Two new quinoxaline-functionalized C60 derivatives with high LUMO levels have been synthesized and applied in organic solar cells. BHJ-OSCs incorporating P3HT as donor and TQMA (or TQBA) as acceptor exhibit an open-circuit voltage (VOC) of 0.76 V (or 0.84 V), which is about 0.12 V (or 0.20 V) higher than PCBM as electron acceptor.
Four 2D Ln–Cd heterometal–organic coordination polymers based on tetranuclear Ln–Cd oxo-cluster with highly selective luminescent sensing of organic molecules and metal cations
Authors: Liu Qi , Wan Fang , Qiu Li-Xia , Sun Yan-Qiong , Chen Yi-Ping
Published: May 2014

Two series of 2D-layered Ln–Cd heterometal–organic complexes based on tetranuclear [Ln2Cd2] oxo-clusters with selective luminescent sensing have been synthesized.
Synthesis of ZnO/Au and ZnO/Ag nanoparticles and their photocatalytic application using UV and visible light
Authors: Fageria Pragati , Gangopadhyay Subhashis , Pande Surojit
Published: May 2014

A simple approach for the deposition of Au and Ag nanoparticles on ZnO surface and to investigate their application in pollutant degradation.
PEI@SiO2: synthesis from diatomite and application for capturing phenolic compounds from aqueous solution
Authors: Chen Zheng-Yong , He Ya-Yuan , Gao Hong-Wen
Published: May 2014

A PEI@SiO2hybrid composite was synthesized for sorption of phenolic compounds.
Single-step alcohol-free synthesis of core–shell nanoparticles of β-casein micelles and silica
Authors: Kerkhofs Stef , Leroux Frederic , Allouche Lionel , Mellaerts Randy , Jammaer Jasper , Aerts Alexander , Kirschhock Christine E. A. , Magusin Pieter C. M. M. , Taulelle Francis , Bals Sara , Van Tendeloo Gustaaf , Martens Johan A.
Published: May 2014

β-Casein is wrapped in a thin shell of SiO2 under biocompatible conditions forming hybrid core–shell nanoparticles.
Surface relaxations as a tool to distinguish the dynamic interfacial properties of films formed by normal and diseased meibomian lipids
Authors: Georgiev Georgi As. , Yokoi Norihiko , Ivanova Slavyana , Tonchev Vesselin , Nencheva Yana , Krastev Rumen
Published: May 2014

The viscoelastic properties of human meibomian lipids (MGS), the major constituent of the tear film (TF) lipid layer, are of key importance for TF stability.
Arrested coalescence behaviour of giant Pickering droplets and colloidosomes stabilised by poly(tert-butylaminoethyl methacrylate) latexes
Authors: Morse Andrew J. , Tan Sin-Ying , Giakoumatos Emma C. , Webber Grant B. , Armes Steven P. , Ata Seher , Wanless Erica J.
Published: May 2014

Coalescence of latex particle covered oil droplets is controlled by the presence of oil-soluble cross-linker in one or both droplets.
Statistical analysis of vesicle morphology dynamics based on a free energy landscape
Authors: Tsuda Soichiro , Suzuki Hiroaki , Yomo Tetsuya
Published: May 2014

We here present a method to reconstruct effective free energy landscapes (FELs) of lipid vesicles from the statistical analysis of a large number of microscope images.
Sorption interactions of plutonium and europium with ordered mesoporous carbon
Authors: Parsons-Moss Tashi , Wang Jinxiu , Jones Stephen , May Erin , Olive Daniel , Dai Zurong , Zavarin Mavrik , Kersting Annie B. , Zhao Dongyuan , Nitsche Heino
Published: May 2014

Batch, X-ray absorption spectroscopy, and transmission electron microscopy techniques revealed oxidized and pristine OMCs as high-capacity plutonium adsorbents, employing different mechanisms.
Deposition of loosely bound organic D–A–π–A′ dyes on sensitized TiO2 film: a possible strategy to suppress charge recombination and enhance power conversion efficiency in dye-sensitized solar cells
Authors: Kang Xiongwu , Zhang Junxiang , Rojas Anthony J. , O'Neil Daniel , Szymanski Paul , Marder Seth R. , El-Sayed Mostafa A.
Published: May 2014

A D–A–π–A′ dye for dye-sensitized solar cells was synthesized via sequential C–H direct arylation; the photovoltaic performance was enhanced by deposition of additional dye on TiO2
Creating superhydrophobic mild steel surfaces for water proofing and oil–water separation
Authors: Lu Yao , Sathasivam Sanjayan , Song Jinlong , Chen Faze , Xu Wenji , Carmalt Claire J. , Parkin Ivan P.
Published: May 2014

The fabricated superhydrophobic–superoleophilic mesh is bent into a V-shape-channel to guarantee floating oils are always in contact with the mesh.
Switchable dielectric behaviour associated with above room-temperature phase transition in N-isopropylbenzylammonium dichloroacetate (N-IPBADC)
Authors: Ji Chengmin , Sun Zhihua , Zhang Shu-Quan , Chen Tianliang , Zhou Pan , Tang Yuanyuan , Zhao Sangen , Luo Junhua
Published: May 2014

An above room-temperature phase transition material, N-isopropylbenzylammonium dichloroacetate, undergoes a phase transition and exhibits switchable dielectric behaviour.
Lysine methylation is an endogenous post-translational modification of tau protein in human brain and a modulator of aggregation propensity
Authors: Funk Kristen E. , Thomas Stefani N. , Schafer Kelsey N. , Cooper Grace L. , Liao Zhongping , Clark David J. , Yang Austin J. , Kuret Jeff
Published: May 2014

In Alzheimer's disease, the microtubule-associated protein tau dissociates from the neuronal cytoskeleton and aggregates to form cytoplasmic inclusions. Although hyperphosphorylation of tau serine and threonine residues is an established trigger of tau misfunction and aggregation, tau modifications extend to lysine residues as well, raising the possibility that different modification signatures depress or promote aggregation propensity depending on site occupancy. To identify lysine residue modifications associated with normal tau function, soluble tau proteins isolated from four cognitively normal human brains were characterized by MS methods. The major detectable lysine modification was found to be methylation, which appeared in the form of mono- and di-methyl lysine residues distributed among at least 11 sites. Unlike tau phosphorylation sites, the frequency of lysine methylation was highest in the microtubule-binding repeat region that mediates both microtubule binding and homotypic interactions. When purified recombinant human tau was modified in vitro through reductive methylation, its ability to promote tubulin polymerization was retained, whereas its aggregation propensity was greatly attenuated at both nucleation and extension steps. These data establish lysine methylation as part of the normal tau post-translational modification signature in human brain, and suggest that it can function in part to protect against pathological tau aggregation.
Boosting decision stumps to do pairwise classification
Authors: Jun Xie , Lu Yu , Lei Zhu , Hui Xue
Published: May 2014

Pairwise classification is a task which predicts whether two samples belong to the same class or not. Boosting provides a way of combining many weak classifiers to produce a strong one and has been regarded as one of the most successful classification methodologies. The problem of pairwise classification is addressed by boosting decision stumps, the simplest weak classifier. Based on gentle AdaBoost, pairwise gentle AdaBoost of decision stumps is proposed to do pairwise classification. To make the classifier deal with a pair of inputs, sample‐weighted linear discriminant analysis (LDA) is proposed, which is tailored to boosting the framework. For pairwise classification, the proposed algorithm shows better performance than traditional boosting of decision stumps on two UCI data sets.
Development of compact directional antenna utilising plane of symmetry for wideband brain stroke detection systems
Authors: Mobashsher A.T. , Abbosh A.
Published: May 2014

Microwave‐based brain stroke detection demands low profile, compact, directive and wideband antennas for efficient imaging using portable systems. Using image theory of electromagnetics, the magnetic symmetry plane of a folded antenna is utilised for its miniaturisation to half of its original volume without sacrificing its penetration capability or radiation directivity. The antenna achieves 63% fractional bandwidth (1.25–2.4 GHz) with 3.5 dBi average gain along the direction of radiation. Both the near‐field and far‐field radiations are characterised to ensure the antenna's applicability in the detection system. Moreover, the radiation safety is also analysed since the antenna has to operate in close proximity to the head. The overall dimensions of the proposed antenna are 0.29λ0 × 0.12λ0 × 0.06λ0 (λ0 = lowest operating wavelength).
Tunable 245 GHz transmitter and receiver in SiGe technology for gas spectroscopy
Authors: Schmalz K. , Mao Y. , Borngräber J. , Neumaier P. , Hübers H.‐W.
Published: May 2014

A 245 GHz sensor system for gas spectroscopy is presented, which includes an integrated SiGe transmitter (TX) and receiver (RX), and a 0.6 m‐long gas absorption cell between the TX and RX modules. The integrated local oscillators (LOs) of TX and RX chips are controlled by two external phase‐locked loops (PLLs), whose reference frequencies are swept with constant frequency offset for a low intermediate frequency of the RX. The RX consists of a differential low‐noise amplifier, an integrated 122 GHz LO with a 1/64 divider, a 90° differential hybrid and an active subharmonic mixer. The TX consists of an integrated 122 GHz LO with a 1/64 divider, and a frequency doubler. The TX and RX chips are fabricated in 0.13 µm SiGe BiCMOS technology with fT/fmax of 300 GHz/500 GHz. Using external dielectric lenses for the TX and RX modules, the gas absorption spectra were measured for acetonitrile and methanol.
Compact tri‐band metamaterial‐inspired antenna based on CRLH resonant structures
Authors: Amani N. , Kamyab M. , Jafargholi A. , Hosseinbeig A. , Meiguni J.S.
Published: May 2014

A single‐cell tri‐band composite right/left‐handed (CRLH) resonant antenna is presented. The antenna is designed on a single‐layer coplanar waveguide‐fed based on the T‐junction discontinuity equivalent circuit. The proposed antenna provides compact size, easy fabrication process, multi‐band feature and higher efficiency in comparison with the previously reported CRLH resonant antennas. The single‐cell CRLH resonant antenna is fabricated and the measurements are consistent with the simulation result.
Miniature wideband bandpass filter based on electric and magnetic coupling paths
Authors: Asadbeigi H. , Virdee B.S.
Published: May 2014

A compact wideband bandpass filter design that provides a sharp roll‐off and low loss performance is presented. The design is based on employing two separate paths between the adjacent resonators constituting the filter, where one path enables electric coupling and the other one magnetic coupling. This structure generates zeros in the filter's transmission response due to the dominance of electric coupling. A fourth‐order filter was fabricated and tested. Correlation between the simulated and measured results is remarkable. The measured results confirm the fractional bandwidth of 70% at the centre frequency of 4.58 GHz, insertion‐loss is <0.55 dB with a return‐loss better than 15 dB in the passband. The filter occupies an area of 4.1 × 17.8 mm, which corresponds to 0.1λo × 0.44λo, where λo is the wavelength of the centre frequency.
Distributed fault detection for a class of second‐order multi‐agent systems: an optimal robust observer approach
Authors: Shi Jiantao , He Xiao , Wang Zidong , Zhou Donghua
Published: May 2014

In this study, the distributed fault detection and isolation problem for a class of second‐order discrete‐time multi‐agent systems (MASs) is studied by using an optimal robust observer approach. The work is based on an MAS with a mean square bounded consensus protocol. The authors prove that for this kind of system, a bank of optimal robust observers can be constructed for a certain agent to detect and isolate the possible faults of its neighbour agents. The main result of this study is to bring forward an existence condition for these observers, which is closely related to the topology structure of the MAS. For the detection of the faults injected in position states, they show that only the position information of the MAS is needed, but for the case of detecting faults in velocity states, both position and velocity measurements are needed. Simulation results are presented to illustrate the effectiveness of the results proposed in this study.
Leader‐following coordination problem with an uncertain leader in a multi‐agent system
Authors: Tang Yutao
Published: May 2014

A leader‐following coordination problem is considered in this study where the active leader is driven by an unknown input. With the help of output regulation and disturbance decoupling, a distributed protocol is proposed to solve this problem. Two cases are studied based on whether the bound of uncertain (disturbance) inputs of the leader is known. When the bound is unknown, an adaptive technique is employed to achieve the goal. Simulations are also given to verify the effectiveness of these controllers.
Stochastic security‐constrained hydrothermal unit commitment considering uncertainty of load forecast, inflows to reservoirs and unavailability of units by a new hybrid decomposition strategy
Authors: Ansari Mohammad Reza , Amjady Nima , Vatani Behdad
Published: May 2014

This study presents a new stochastic security‐constrained hydrothermal unit commitment (SSCHTUC) model considering the uncertainty of load forecast, prediction of inflows to hydro reservoirs and unavailability of units. In addition, the proposed SSCHTUC includes AC network modelling. To cope with the large‐scale and mixed‐integer non‐linear nature of the model, a new hybrid decomposition strategy composed of generalised Benders decomposition and outer approximation/equality relaxation (OA/ER) is proposed. In addition, to handle the uncertainty sources, a combination of scenario approach and two‐stage stochastic programming is suggested. The proposed SSCHTUC model and decomposition strategy are tested on the IEEE 9‐bus and 118‐bus test systems. Obtained results illustrate the effectiveness of the developed approach.
One‐step hydrothermal synthesis of the Ag/AgI heterojunction with highly enhanced visible‐light photocatalytic performances
Authors: Wang Xinjun , Wan Xiaoli , Li Wuqi , Chen Xuenian
Published: May 2014

The Ag/AgI heterojunction was prepared by a facile, one‐step and low‐temperature hydrothermal synthesis method with P, I2 and Ag2O. The approach proves a green and simple route to the products, which avoided multiple‐step synthesis and the subsequent time‐consuming photoreduction. The samples were carefully characterised by X‐ray diffraction, X‐ray photoelectronic spectra, scanning electron microscopy, transmission electron micrographs and ultraviolet–visible‐light techniques. The results show that Ag nanoparticles were uniformly distributed on the surface of AgI and the heterostructure was formed. Under visible light, the photocatalytic activity of the Ag/AgI composites for the degradation of rhodamine B (RhB) was efficient and much higher than that of pure AgI. In particular, the Ag/AgI composites (at 120°C for 4 h) exhibited the best photocatalytic activity, and nearly 98% of RhB was degraded within 20 min. Remarkably, the photocatalytic degradation followed the pseudo‐first‐order reaction model and the corresponding apparent first‐order rate constant of 0.157 min−1 which is five times more than that of pure AgI. The enhanced photocatalytic activity of Ag/AgI can be attributed to the strong surface plasmon resonances.
Generating accurate dipole moment surfaces using modified Shepard interpolation
Authors: Morris Michael , Jordan Meredith J. T.
Published: May 2014

We outline an approach for building molecular dipole moment surfaces using modified Shepard interpolation. Our approach is highly automated, requires minimal parameterization, and is iteratively improvable. Using the water molecule as a test case, we investigate how different aspects of the interpolation scheme affect the rate of convergence of calculated IR spectral line intensities. It is found that the interpolation scheme is sensitive to coordinate singularities present at linear geometries. Due to the generally monotonic nature of the dipole moment surface, the one-part weight function is found to be more effective than the more complicated two-part variant, with first-order interpolation also giving better-than-expected results. Almost all sensible schemes for choosing interpolation reference data points are found to exhibit acceptable convergence behavior.
Daubechies wavelets for linear scaling density functional theory
Authors: Mohr Stephan , Ratcliff Laura E. , Boulanger Paul , Genovese Luigi , Caliste Damien , Deutsch Thierry , Goedecker Stefan
Published: May 2014

We demonstrate that Daubechies wavelets can be used to construct a minimal set of optimized localized adaptively contracted basis functions in which the Kohn-Sham orbitals can be represented with an arbitrarily high, controllable precision. Ground state energies and the forces acting on the ions can be calculated in this basis with the same accuracy as if they were calculated directly in a Daubechies wavelets basis, provided that the amplitude of these adaptively contracted basis functions is sufficiently small on the surface of the localization region, which is guaranteed by the optimization procedure described in this work. This approach reduces the computational costs of density functional theory calculations, and can be combined with sparse matrix algebra to obtain linear scaling with respect to the number of electrons in the system. Calculations on systems of 10 000 atoms or more thus become feasible in a systematic basis set with moderate computational resources. Further computational savings can be achieved by exploiting the similarity of the adaptively contracted basis functions for closely related environments, e.g., in geometry optimizations or combined calculations of neutral and charged systems.
Existence and Regularity of Invariant Measures for the Three Dimensional Stochastic Primitive Equations
Authors: Glatt-Holtz Nathan , Kukavica Igor , Vicol Vlad , Ziane Mohammed
Published: May 2014

We establish the continuity of the Markovian semigroup associated with strong solutions of the stochastic 3D Primitive Equations, and prove the existence of an invariant measure. The proof is based on new moment bounds for strong solutions. The invariant measure is supported on strong solutions and is furthermore shown to have higher regularity properties.
An analytical coarse-graining method which preserves the free energy, structural correlations, and thermodynamic state of polymer melts from the atomistic to the mesoscale
Authors: McCarty J. , Clark A. J. , Copperman J. , Guenza M. G.
Published: May 2014

Structural and thermodynamic consistency of coarse-graining models across multiple length scales is essential for the predictive role of multi-scale modeling and molecular dynamic simulations that use mesoscale descriptions. Our approach is a coarse-grained model based on integral equation theory, which can represent polymer chains at variable levels of chemical details. The model is analytical and depends on molecular and thermodynamic parameters of the system under study, as well as on the direct correlation function in the k → 0 limit, c0. A numerical solution to the PRISM integral equations is used to determine c0, by adjusting the value of the effective hard sphere diameter, dHS, to agree with the predicted equation of state. This single quantity parameterizes the coarse-grained potential, which is used to perform mesoscale simulations that are directly compared with atomistic-level simulations of the same system. We test our coarse-graining formalism by comparing structural correlations, isothermal compressibility, equation of state, Helmholtz and Gibbs free energies, and potential energy and entropy using both united atom and coarse-grained descriptions. We find quantitative agreement between the analytical formalism for the thermodynamic properties, and the results of Molecular Dynamics simulations, independent of the chosen level of representation. In the mesoscale description, the potential energy of the soft-particle interaction becomes a free energy in the coarse-grained coordinates which preserves the excess free energy from an ideal gas across all levels of description. The structural consistency between the united-atom and mesoscale descriptions means the relative entropy between descriptions has been minimized without any variational optimization parameters. The approach is general and applicable to any polymeric system in different thermodynamic conditions.
Reaction mechanisms and kinetics of the iminovinylidene radical with NO: Ab initio study
Authors: Hsiao Ming-Kai , Chung Yi-Hua , Hung Yu-Ming , Chen Hui-Lung
Published: May 2014

The nitric oxide (NO) is a notorious compound for polluting environment. Recent year, removing nitric oxide from the atmosphere becomes a focus of the investigation. In our work, we study the iminovinylidene (HNCC) radical reacted with NO molecule. The mechanism and kinetic for reaction of the HNCC radical with the NO molecule is investigated via considering the possible channels of the N and O atoms of NO attacking the N and C atoms of the HNCC based on the high level ab initio molecular orbital calculations in conjunction with variational TST and RRKM calculations. The species involved have been optimized at the B3LYP/6-311++G(3df,2p) level and their single-point energies are refined by the CCSD(T)/aug-cc-PVQZ//B3LYP/6-311++G(3df,2p) method. The calculated potential energy surfaces indicated that energetically the most favorable channel for the HNCC + NO reaction was predicted to be the formation of HNC+CNO (P8) product via the addition reaction of the C atom of HNCC radical and the N atom of NO with the head to head orientation. To rationalize the scenario of the calculated results, we also employ the Fukui functions and HSAB theory to seek for a possible explanation. In addition, the reaction rate constants were calculated using VariFlex code, and the results show that the total rate coefficient, ktotal, at Ar pressure 760 Torr can be represented with an equation: ktotal = 6.433 × 10−11 T 0.100 exp(0.275 kcal mol−1/RT) at T = 298–3000 K, in units of cm3 molecule−1 s−1.
Ferroelectric domain structure of anisotropically strained NaNbO3 epitaxial thin films
Authors: Schwarzkopf J. , Braun D. , Schmidbauer M. , Duk A. , Wördenweber R.
Published: May 2014

NaNbO3 thin films have been grown under anisotropic biaxial strain on several oxide substrates by liquid-delivery spin metalorganic chemical vapor deposition. Compressive lattice strain of different magnitude, induced by the deposition of NaNbO3 films with varying film thickness on NdGaO3 single crystalline substrates, leads to modifications of film orientation and phase symmetry, which are similar to the phase transitions in Pb-containing oxides near the morphotropic phase boundary. Piezoresponse force microscopy measurements exhibit large out-of-plane polarization components, but no distinctive domain structure, while C-V measurements indicate relaxor properties in these films. When tensile strain is provoked by the epitaxial growth on DyScO3, TbScO3, and GdScO3 single crystalline substrates, NaNbO3 films behave rather like a normal ferroelectric. The application of these rare-earth scandate substrates yields well-ordered ferroelectric stripe domains of the type a1/a2 with coherent domain walls aligned along the [001] substrate direction as long as the films are fully strained. With increasing plastic lattice relaxation, initially, a 2D domain pattern with still exclusively in-plane electric polarization, and finally, domains with in-plane and out-of-plane polar components evolve.
Temperature dependence of photoluminescence properties in a thermally activated delayed fluorescence emitter
Authors: Niwa Akitsugu , Kobayashi Takashi , Nagase Takashi , Goushi Kenichi , Adachi Chihaya , Naito Hiroyoshi
Published: May 2014

Using steady-state and time-resolved photoluminescence (PL) spectroscopy, we have investigated the temperature dependence of PL properties of 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyano-benzene (4CzIPN), which have a small energy gap between its singlet and triplet excited states and thus exhibits efficient thermally activated delayed fluorescence [H. Uoyama et al., Nature 492, 235 (2012)]. Below around 100 K, PL quantum efficiency of 4CzIPN thin films is largely suppressed and strong photoexcitation intensity dependence appears. These features can be explained by using rate equations for the densities of singlet and triplet excited states considering a triplet-triplet annihilation process.
Explicit quasi-periodic solutions of the Vakhnenko equation
Authors: Zhai Yunyun , Geng Xianguo , He Guoliang
Published: May 2014

The trigonal curve associated with the Vakhnenko equation is introduced by using the Lax matrix for the nth stationary positive flow. Based on the theory of the trigonal curve and the properties of the three kinds of Abel differentials, the Riemann theta function representation for the Baker-Akhiezer function is derived, from which the straightening out of flows in the Jacobian variety is exactly given through the Abel maps. We finally arrive at quasi-periodic solutions of the Vakhnenko equation.
Measurement of total ultrasonic power using thermal expansion and change in buoyancy of an absorbing target
Authors: Dubey P. K. , Kumar Yudhisther , Gupta Reeta , Jain Anshul , Gohiya Chandrashekhar
Published: May 2014

The Radiation Force Balance (RFB) technique is well established and most widely used for the measurement of total ultrasonic power radiated by ultrasonic transducer. The technique is used as a primary standard for calibration of ultrasonic transducers with relatively fair uncertainty in the low power (below 1 W) regime. In this technique, uncertainty comparatively increases in the range of few watts wherein the effects such as thermal heating of the target, cavitations, and acoustic streaming dominate. In addition, error in the measurement of ultrasonic power is also caused due to movement of absorber at relatively high radiated force which occurs at high power level. In this article a new technique is proposed which does not measure the balance output during transducer energized state as done in RFB. It utilizes the change in buoyancy of the absorbing target due to local thermal heating. The linear thermal expansion of the target changes the apparent mass in water due to buoyancy change. This forms the basis for the measurement of ultrasonic power particularly in watts range. The proposed method comparatively reduces uncertainty caused by various ultrasonic effects that occur at high power such as overshoot due to momentum of target at higher radiated force. The functionality of the technique has been tested and compared with the existing internationally recommended RFB technique.
Note: Raman microspectroscopy integrated with fluorescence and dark field imaging
Authors: Li Haibo , Wang Hailong , Huang Dianshuai , Liang Lijia , Gu Yuejiao , Liang Chongyang , Xu Shuping , Xu Weiqing
Published: May 2014

A Raman detection platform integrated with both fluorescence and dark field microscopes was built for in situ Raman detection with the assistance of fluorescence and dark field imaging to locate the target micro regions. Cells and organelles can be easily found via fluorescence imaging with labeling techniques. Besides, nano-sized particles could be observed and located by dark field microscopes. Therefore, comparing with the commercial Raman spectrometers, much more researches based on Raman spectroscopy could be carried out on this integrated Raman platform, especially in the fields of analyzing biological tissues and subwavelength samples.
Applying of microwave asymmetrical double-ridged waveguide for measuring of the integrated optical electrodeless electric field sensor sensitivity
Authors: Zhuravlev Anton A. , Volkhin Igor L. , Ponomarev Roman S. , Smirnova Anna N. , Shevtsov Denis I. , Pervadchuk Vladimir P.
Published: May 2014

We present a new method for investigation of sensitivity of the integrated optical electrodeless electric field sensor. This method is based on a compact microwave asymmetrical double-ridged waveguide with regular inhomogeneities. Small dimensions of the waveguide along with medium power of the microwave generator produce a strong electric field. The efficiency of the presented experimental unit was verified in the course of testing of the real integrated optical electrodeless electric field sensor (E-sensor).
Stark spectroscopy of CdTe and CdMnTe quantum dots embedded in n-i-p diodes
Authors: Kłopotowski Ł. , Fronc K. , Wojnar P. , Wiater M. , Wojtowicz T. , Karczewski G.
Published: May 2014

We investigate charging effects in CdTe and Cd1−xMnxTe quantum dots embedded in n-i-p diodes. The tunneling of holes out of the dots at reverse bias and hole injection at forward bias control the dot charge state and allow for its electric field tuning. Furthermore, we analyze the Stark shifts of the photoluminescence transitions and evaluate the effect of the electric field on the binding of the observed excitonic complexes. We find that the binding can be strengthened or weakened depending on the zero-field alignment of the electron and hole wavefunctions.
Mode imaging and loss evaluation of semiconductor waveguides
Authors: Mochizuki Toshimitsu , Kim Changsu , Yoshita Masahiro , Nakamura Takahiro , Akiyama Hidefumi , Pfeiffer Loren N. , West Ken W.
Published: May 2014

An imaging and loss evaluation method for semiconductor waveguides coupled with non-doped quantum wells is presented. Using the internal emission of the wells as a probe light source, the numbers and widths of the modes of waveguides with various ridge sizes were evaluated by CCD imaging, and the obtained values were consistent with effective index method calculation. Waveguide internal losses were obtained from analyses of the Fabry-Pérot fringes of waveguide emission spectra. We quantified the quality of 29 single-mode waveguide samples as an internal loss and variation of 10.2 ± 0.6  cm−1.
Note: A rigid piezo motor with large output force and an effective method to reduce sliding friction force
Authors: Guo Ying , Hou Yubin , Lu Qingyou
Published: May 2014

We present a completely practical TunaDrive piezo motor. It consists of a central piezo stack sandwiched by two arm piezo stacks and two leg piezo stacks, respectively, which is then sandwiched and spring-clamped by a pair of parallel polished sapphire rods. It works by alternatively fast expanding and contracting the arm/leg stacks while slowly expanding/contracting the central stack simultaneously. The key point is that sufficiently fast expanding and contracting a limb stack can make its two sliding friction forces well cancel, resulting in the total sliding friction force is <10% of the total static friction force, which can help increase output force greatly. The piezo motor's high compactness, precision, and output force make it perfect in building a high-quality harsh-condition (vibration resistant) atomic resolution scanning probe microscope.
Dynamic tracking of magnetic nanoparticles for mapping microvascular networks using a clinical 1.5 T magnetic resonance scanner
Authors: Olamaei Nina , Cheriet Farida , Deschênes Sylvain , Martel Sylvain
Published: May 2014

Being able to visualize blood vessels with an inner diameter of less than 150 μm is the present limit of modern medical imaging modalities and it becomes an important issue to advance state-of-the-art medical imaging, diagnostics, surgery, and targeted interventions. In cancer therapy, such capability would provide the information required for new delivery methods such as magnetic resonance navigation to navigate therapeutic agents along a planned trajectory deeper in the vasculature and hence closer to the region to be treated for enhancing the therapeutic index. To demonstrate the possibility of gathering images of microvascular networks dynamically and beyond the limitation of medical imaging modalities, the susceptibility artifact was used as the contrast mechanism in magnetic resonance imaging (MRI) to detect magnetic micro-aggregations of iron-oxide nanoparticles (150 ± 20 μm in diameter) as they were injected in a 2D synthetic microvascular network. Magnetic entities cause susceptibility artifacts in the images by disrupting the MRI's homogeneous magnetic field in a much larger scale than their actual size. The position of the artifact reflects the position of the aggregations in the vascular system. The calculated positions of discrete-time scans were extracted and assembled to build up the distribution of the vascular network. The results suggest that this method could be used to gather images of blood vessels beyond the spatial resolution of clinical medical imaging modalities with a measured average error confirmed on a 2D reconstruction of the micro-vessels of approximately half of a pixel's size.
Three-dimensional polymeric structures of single-wall carbon nanotubes
Authors: Lian Chao-Sheng , Wang Jian-Tao
Published: May 2014

We explore by ab initio calculations the possible crystalline phases of polymerized single-wall carbon nanotubes (P-SWNTs) and determine their structural, elastic, and electronic properties. Based on direct cross-linking and intertube sliding-assisted cross-linking mechanisms, we have identified a series of stable three-dimensional polymeric structures for the zigzag nanotubes up to (10,0). Among proposed P-SWNT phases, the structures with favorable diamond-like sp3 intertube bonding configuration and small tube cross-section distortion are found to be the most energetically stable ones. These polymeric crystalline phases exhibit high bulk and shear moduli superior to SWNT bundles, and show metallic or semiconducting properties depending on the diameter of constituent tubes. We also propose by hydrostatic pressure simulations that the intertube sliding between van der Waals bonded nanotubes may be an effective route to promote the polymerization of SWNTs under pressure.
On the ordinary mode instability for low beta plasmas
Authors: Hadi F. , Bashir M. F. , Qamar A. , Yoon P. H. , Schlickeiser R.
Published: May 2014

The purely growing ordinary (O) mode instability, first discussed by Davidson and Wu [Phys. Fluids 13, 1407 (1970)], has recently received renewed attention owing to its potential applicability to the solar wind plasma. In a series of papers, Ibscher, Schlickeiser, and their colleagues [Phys. Plasmas 19, 072116 (2012); ibid. 20, 012103 (2013); ibid. 20, 042121 (2013); ibid. 21, 022110 (2014)] revisited the O mode instability and extended it to the low-beta plasma regime by considering a counter-streaming bi-Maxwellian model. However, the O-mode instability is, thus, far discussed only on the basis of the marginal stability condition rather than actual numerical solutions of the dispersion relation. The present paper revisits the O-mode instability by considering the actual complex roots. The marginal stability condition as a function of the (electron) temperature anisotropy and beta naturally emerges in such a scheme.
Characterizing penetration depths of multi-wavelength surface plasmon resonance sensor using silica beads
Authors: Liu Anping , Peng Jinlin , Li Guangshan
Published: May 2014

A multi-wavelength surface plasmon resonance (Dr-SPR) sensor consisting of three excitation wavelengths at 665 nm, 980 nm, and 1480 nm has been demonstrated. The use of three excitation wavelengths not only provides three penetration depths of 186 nm, 570 nm, and 1395 nm but also enables depth-resolving capability. To verify its depth-resolving capability, three silica bead sizes of 150 nm, 540 nm, and 1860 nm were used to form bead monolayers with different thicknesses on the sensor chip surface. It is found that the Dr-SPR produces the maximum response when the bead size matches the penetration depth. The demonstration provides a unique technique to characterize penetration depths of SPR using multiple excitation wavelengths. It also opens a variety of applications in which particles can be used as a biomedical/biochemical marker and tracked by the Dr-SPR.
Interlayer-glide-driven isosymmetric phase transition in compressed In2Se3
Authors: Ke Feng , Liu Cailong , Gao Yang , Zhang Junkai , Tan Dayong , Han Yonghao , Ma Yanzhang , Shu Jinfu , Yang Wenge , Chen Bin , Mao Ho-Kwang , Chen Xiao-Jia , Gao Chunxiao
Published: May 2014

We report an anomalous phase transition in compressed In2Se3. The high-pressure studies indicate that In2Se3 transforms to a new isosymmetric R-3m structure at 0.8 GPa whilst the volume collapses by ∼7%. This phase transition involves a pressure-induced interlayer shear glide with respect to one another. Consequently, the outer Se atoms of one sheet locate into the interstitial sites of three Se atoms in the neighboring sheets that are weakly connected by van der Waals interaction. Interestingly, this interlayer shear glide changes the stacking sequence significantly but leaves crystal symmetry unaffected. This study provides an insight to the mechanisms of the intriguing isosymmetric phase transition.
Electrocaloric effect in BaTiO3: A first-principles-based study on the effect of misfit strain
Authors: Marathe Madhura , Ederer Claude
Published: May 2014

We address the question of how the electrocaloric effect in epitaxial thin films of the prototypical ferroelectric BaTiO3 is affected by the clamping to the substrate and by substrate-induced misfit strain. We use molecular dynamics simulations and a first-principles-based effective Hamiltonian to calculate the adiabatic temperature change ΔT under different epitaxial constraints. Our results demonstrate that, consistent with phenomenological theory, clamping by the substrate reduces the maximum ΔT compared to bulk BaTiO3. On the other hand, compressive misfit-strain leads to a strong increase of ΔT and shifts the maximum of the electrocaloric effect to higher temperatures. A rather small compressive strain of –0.75% is sufficient to obtain a ΔT that is larger than the corresponding bulk value.
Magnetically multiplexed heating of single domain nanoparticles
Authors: Christiansen M. G. , Senko A. W. , Chen R. , Romero G. , Anikeeva P.
Published: May 2014

Selective hysteretic heating of multiple collocated types of single domain magnetic nanoparticles (SDMNPs) by alternating magnetic fields (AMFs) may offer a useful tool for biomedical applications. The possibility of “magnetothermal multiplexing” has not yet been realized, in part due to prevalent use of linear response theory to model SDMNP heating in AMFs. Dynamic hysteresis modeling suggests that specific driving conditions play an underappreciated role in determining optimal material selection strategies for high heat dissipation. Motivated by this observation, magnetothermal multiplexing is theoretically predicted and empirically demonstrated by selecting SDMNPs with properties that suggest optimal hysteretic heat dissipation at dissimilar AMF driving conditions. This form of multiplexing could effectively offer multiple channels for minimally invasive biological signaling applications.
Cavity-enhanced single photon emission from site-controlled In(Ga)As quantum dots fabricated using nanoimprint lithography
Authors: Tommila J. , Belykh V. V. , Hakkarainen T. V. , Heinonen E. , Sibeldin N. N. , Schramm A. , Guina M.
Published: May 2014

We report on the emission dynamics of single In(Ga)As quantum dots formed in etched GaAs pits and integrated into micropillar cavities. The site-controlled quantum dots were fabricated by molecular beam epitaxy on nanoimprint lithography patterned GaAs(001) surfaces. Triggered single photon emission confirmed by photon autocorrelation measurements is demonstrated. Time-resolved photoluminescence experiments clearly show an effect of the cavity on the spontaneous emission rate of the quantum dot.