bluuebunny/crossref_metadata_2025 huggingface dataset:
Effective bromo and chloro peroxidation catalysed by tungsten(vi) amino triphenolate complexes
Authors: Badetti Elena , Romano Francesco , Marchiò Luciano , Taşkesenlioğlu Sara , Daştan Arif , Zonta Cristiano , Licini Giulia
Published: June 2016

Amino triphenolate tungsten(vi) complexes have been prepared and they proved to be efficient catalysts in haloperoxidation reactions using hydrogen peroxide as a terminal oxidant and inorganic sources of halides.
Optical resonance and charge transfer behavior of patterned WO3 microdisc arrays
Authors: Jeong Hye Won , Chae Weon-Sik , Song Bokyung , Cho Chang-Hee , Baek Seong-Ho , Park Yiseul , Park Hyunwoong
Published: June 2016

Patterned WO3 microdisc arrays exhibit excellent photoelectrochemical performances, owing to enhanced light absorption and effective charge separation.
AIE fluorophore with enhanced cellular uptake for tracking esterase-activated release of taurine and ROS scavenging
Authors: Wang Jun , Wu Yinglong , Zeng Fang , Huang Shuailing , Wu Shuizhu
Published: June 2016

Fluorophores with aggregation-induced emission (AIE) characteristics are attractive and versatile tools for both chemical sensing and biological imaging. Herein, we designed and synthesized a fluorescent light-up system CTPE-Tau with enhanced cellular uptake ability. The system possesses several advantages, such as a large Stokes shift, low cytotoxicity, and good photostability. Also, it has been successfully utilized to track esterase-activated release of taurine and to scavenge intracellular ROS, and shows great potential for trackable visualized therapy.
Role of the transmembrane domain in SNARE protein mediated membrane fusion: peptide nucleic acid/peptide model systems
Authors: Wehland Jan-Dirk , Lygina Antonina S. , Kumar Pawan , Guha Samit , Hubrich Barbara E. , Jahn Reinhard , Diederichsen Ulf
Published: June 2016

Analogs of the Soluble NSF (N-ethylmaleimide-sensitive factor) Attachment Protein Receptor proteins (SNAREs) for mediation of vesicle fusion.
Substrate transport pathway inside outward open conformation of EmrD: a molecular dynamics simulation study
Authors: Xianwei Tan , Diannan Lu , Boxiong Wang
Published: June 2016

The EmrD transporter, which is a classical major facilitator superfamily (MFS) protein, can extrude a range of drug molecules out ofE. coil.
High-throughput computational screening of nanoporous adsorbents for CO2 capture from natural gas
Authors: Braun Efrem , Zurhelle Alexander F. , Thijssen Wouter , Schnell Sondre K. , Lin Li-Chiang , Kim Jihan , Thompson Joshua A. , Smit Berend
Published: June 2016

Designing adsorbents for the separation of natural gas components requires an understanding of how molecular structure affects gas adsorption.
Porous silicon–graphene oxide core–shell nanoparticles for targeted delivery of siRNA to the injured brain
Authors: Joo Jinmyoung , Kwon Ester J. , Kang Jinyoung , Skalak Matthew , Anglin Emily J. , Mann Aman P. , Ruoslahti Erkki , Bhatia Sangeeta N. , Sailor Michael J.
Published: June 2016

A chemically targeted luminescent porous silicon–graphene oxide core–shell nanoparticle delivers siRNA for more effective gene silencing.
Sensitive and simple simultaneous determination of morphine and codeine using a Zn2SnO4nanoparticle/graphene composite modified electrochemical sensor
Authors: Bagheri Hasan , Khoshsafar Hosein , Afkhami Abbas , Amidi Salimeh
Published: June 2016

Simultaneous determination of morphine and codeine using a nanocomposite modified electrochemical sensor.
Recent developments in the group-1B-metal-catalyzed synthesis of pyrroles
Authors: Zhou Ni-Ni , Zhu Hai-Tao , Yang De-Suo , Guan Zheng-Hui
Published: June 2016

Pyrroles are important synthetic targets as a result of their occurrence in numerous biologically active molecules, their important roles in diverse living processes, and their utility as versatile intermediates.
Enantioselective synthesis of (+)-brevipolide H
Authors: Chen Ching-Nung , Hou Duen-Ren
Published: June 2016

The enantioselective synthesis of natural brevipolide H is reported for the first time.
Thermal 1,3-dipolar cycloaddition reaction of azomethine imines with active esters
Authors: He Liwenze , Liu Lin , Han Runfeng , Zhang Weiwei , Xie Xingang , She Xuegong
Published: June 2016

A simple and efficient [3 + 2] cycloaddition reaction between active esters and azomethine imines to afford pyrazolidinone derivatives has been developed. It does not involve a catalyst and commonly uses two substrates.
Synthesis of β-acetoxy alcohols by PhI(OAc)2-mediated metal-free diastereoselective β-acetoxylation of alcohols
Authors: Zhao Chun-Yang , Li Liang-Gui , Liu Qing-Rong , Pan Cheng-Xue , Su Gui-Fa , Mo Dong-Liang
Published: June 2016

A PhI(OAc)2-mediated metal-free β-acetoxylation method to synthesize diverse β-acetoxy alcohols has been achieved in good yields with high diastereoselectivity.
Synthesis of cyclopenta-fused polycyclic aromatic hydrocarbons utilizing aryl-substituted anilines
Authors: Choi Yeojin , Chatterjee Tanmay , Kim Jun , Kim Jun Soo , Cho Eun Jin
Published: June 2016

Cyclopenta-fused polycyclic aromatic hydrocarbons were synthesized from readily available 2-aryl-substituted anilines under extremely mild conditions.
The influence of hydrogen bonding on radical chain-growth parameters for butyl methacrylate/2-hydroxyethyl acrylate solution copolymerization
Authors: Schier Jan E. S. , Hutchinson Robin A.
Published: June 2016

Pulsed laser polymerizations coupled with size exclusion chromatography (PLP-SEC) and NMR analyses were performed to determine radical kinetic parameters for BMA/HEA, with a focus on the effect of solvent choice and H-bonding on both copolymer composition and copolymer-averaged propagation rate coefficients.
“Click-fluors”: triazole-linked saccharide sensors
Authors: Zhai Wenlei , Chapin Brette M. , Yoshizawa Akina , Wang Hui-Chen , Hodge Stephen A. , James Tony D. , Anslyn Eric V. , Fossey John S.
Published: June 2016

A series of boronic acid-containing saccharide receptors was synthesised via copper catalysed azide–alkyne cycloaddition (CuAAC) reactions.
Novel rhodanines with anticancer activity: design, synthesis and CoMSIA study
Authors: Mandal Subhankar P. , Mithuna Mithuna , Garg Aakriti , Sahetya Sanjana S. , Nagendra S. R. , Sripad H. S. , Manjunath Mendon Manisha , Sitaram Sitaram , Soni Mukesh , Baig R. Nasir , Kumar S. Vasanth , Kumar B. R. Prashantha
Published: June 2016

A library of novel rhodanines are reported for their anticancer activity along with the 3D QSAR.
Discovery of novel chemical scaffolds as RhoA inhibitors using virtual screening, synthesis, and bioactivity evaluation
Authors: Zhang Chao , Wang Hui-Jie , Bao Qi-Chao , Bian Jin-Lei , Yang Ying-Rui , You Qi-Dong , Xu Xiao-Li
Published: June 2016

RhoA has been implicated in diverse cellular functions and is a potential cancer therapeutic target.
Structure–property relationships for bis-diketopyrrolopyrrole molecules in organic photovoltaics
Authors: Wang Qiang (Mike) , van Franeker Jacobus J. , Bruijnaers Bardo J. , Wienk Martijn M. , Janssen René A. J.
Published: June 2016

By comparing the morphology and solar cell performance it is possible to identify structure–property relationships for bis-diketopyrrolopyrrole molecules.
Nitrogen-doped porous carbon derived from a bimetallic metal–organic framework as highly efficient electrodes for flow-through deionization capacitors
Authors: Wang Zhuo , Yan Tingting , Fang Jianhui , Shi Liyi , Zhang Dengsong
Published: June 2016

Nitrogen-doped porous carbon derived from a bimetallic metal–organic framework was demonstrated as highly efficient electrodes for flow-through deionization capacitors.
Co-doped Ni hydroxide and oxide nanosheet networks: laser-assisted synthesis, effective doping, and ultrahigh pseudocapacitor performance
Authors: Liang Dewei , Wu Shouliang , Liu Jun , Tian Zhenfei , Liang Changhao
Published: June 2016

Liquid phase laser-assisted nanosheet networks show ultrahigh specific capacitance due to their improved conductivity, mesoporosity, low crystallinity and high specific surface area.
Enhancing the catalytic activity of Ru NPs deposited with carbon species in yolk–shell nanostructures
Authors: Guo Miao , Lan Guojun , Peng Juan , Li Mingrun , Yang Qihua , Li Can
Published: June 2016

An efficient H2 pyrolysis method was developed to remove stabilizers on metal surfaces with Ru–poly(amindoamine) as the model. Ru NPs after pyrolysis with the TOF as high as 20 300 h−1 are among the most active solid catalysts for toluene hydrogenation. The high catalytic activity could be mainly attributed to the high exposure degree and accelerating effect of C and N residues at the Ru surface.
The quantum mechanics derived atomistic mechanism underlying the acceleration of catalytic CO oxidation on Pt(110) by surface acoustic waves
Authors: An Qi , Qian Jin , Nielsen Robert R. , Sementa Luca , Barcaro Giovanni , Negreiros Fabio R. , Fortunelli Alessandro , Goddard III William A.
Published: June 2016

Quantum mechanics simulations unveil the mechanism of surface acoustic waves (SAW) enhancement of CO oxidation on Pt(110) via shock spikes.
Interconnected honeycomb-like porous carbon derived from plane tree fluff for high performance supercapacitors
Authors: Zhang Yunqiang , Liu Xuan , Wang Shulan , Dou Shixue , Li Li
Published: June 2016

Three-dimensional interconnected honeycomb-like porous carbon is successfully fabricated via activated and graphitized plane tree fluff with the aid of Co2+ and KOH.
A simple perylene diimide derivative with a highly twisted geometry as an electron acceptor for efficient organic solar cells
Authors: Li Shuixing , Liu Wenqing , Li Chang-Zhi , Liu Feng , Zhang Yingzhu , Shi Minmin , Chen Hongzheng , Russell Thomas P.
Published: June 2016

A perylene diimide based electron acceptor with a simple structure, low-cost and high efficiency of 5.65% is presented here.
Decorating nanoporous ZIF-67-derived NiCo2O4 shells on a Co3O4 nanowire array core for battery-type electrodes with enhanced energy storage performance
Authors: Yu Dongbo , Wu Bin , Ge Liang , Wu Liang , Wang Huanting , Xu Tongwen
Published: June 2016

A perfectly intact ZIF-67-derived NiCo2O4 shell had been decorated on a Co3O4 nanowire core. Due to the specific core–shell structure, the resulting hybrid nanowire array exhibited remarkable electrochemical properties.
Cellular internalisation, bioimaging and dark and photodynamic cytotoxicity of silica nanoparticles doped by {Mo6I8}4+ metal clusters
Authors: Solovieva Anastasiya O. , Vorotnikov Yuri A. , Trifonova Kristina E. , Efremova Olga A. , Krasilnikova Anna A. , Brylev Konstantin A. , Vorontsova Elena V. , Avrorov Pavel A. , Shestopalova Lidiya V. , Poveshchenko Alexander F. , Mironov Yuri V. , Shestopalov Michael A.
Published: June 2016

{Mo6I8}@SiO2 nanoparticles for biomedical applications.
Engineering the electronic structure and optical properties of g-C3N4 by non-metal ion doping
Authors: Guo Qianyi , Zhang Yuanhao , Qiu Jianrong , Dong Guoping
Published: June 2016

The normalized PL emission spectra of graphite-like carbon nitride (g-C3N4) modified with different non-metal ions (boron and sulfur) exhibit interesting scientific variation.
Thermochromic upconversion nanoparticles for visual temperature sensors with high thermal, spatial and temporal resolution
Authors: Savchuk Ol. A. , Carvajal J. J. , Cascales C. , Massons J. , Aguiló M. , . Díaz F
Published: June 2016

A luminescent thermometer changing from blue to red as temperature increases and based on Yb3+,Tm3+:GdVO4@SiO2 nanoparticles excited at 980 nm is presented.
Enhanced fluorescence properties of carbon dots in polymer films
Authors: Liu Yamin , Wang Ping , Shiral Fernando K. A. , LeCroy Gregory E. , Maimaiti Halidan , Harruff-Miller Barbara A. , Lewis William K. , Bunker Christopher E. , Hou Zhi-Ling , Sun Ya-Ping
Published: June 2016

Fluorescence intensities of carbon dots are substantially enhanced in the confined environment in polymeric films.
Halide-free synthesis of Au nanoplates and monitoring the shape evolution process through a marker experiment
Authors: Chen Lei , Hu Huicheng , Liu Qipeng , Ji Fei , Chen Suli , Xu Yong , Zhang Qiao
Published: June 2016

We demonstrate that uniform Au nanoplates capped with a nontoxic ligand have been prepared through a seeded growth method using Au/Ag nanorings as the template.
Ten Funding Myths Demystified!
Authors: Goldman Amy
Published: June 2016

This article addresses 10 common misconceptions about the availability of funding and coverage for speech-generating devices (SGDs). Speech-language pathologists who will be evaluating individuals who can benefit from SGDs should become familiar with their responsibilities to ensure the process concludes with successful procurement of the recommended device. A reminder of ethical practices and additional resources are provided to the reader.
Fabrication of doped Pb(Zr,Ti)O3 capacitors on Pt substrates with different orientations
Authors: Tamano R. , Amano T. , Takada Y. , Okamoto N. , Saito T. , Yoshimura T. , Fujimura N. , Higuchi K. , Kitajima A.
Published: June 2016

The effects of crystallographic orientation on the ferroelectric properties of Pb(Zr,Ti)O3 (PZT) thin films grown on (111) and (100)‐oriented Pt substrates are investigated. The effects of doping PZT with species X (forming PXZT) thin films (Pb:X:Zr:Ti, 113:3:30:70; X = La, Nb, or Y) using chemical solution deposition were studied. The crystallinity of all PXZT films was almost identical. The remnant polarisation of the un‐doped, La‐, Nb‐, and Y‐doped PZT capacitors with Pt(111) bottom electrodes were 133.4, 64.7, 60.2, and 98.4 µC/cm2, respectively. In ferroelectric capacitors with Pt(100) bottom electrodes, the remnant polarisations were 185.6, 148.1, 103.1, and 135.7 µC/cm2, respectively. The remnant polarisation was larger with Pt(100) than with Pt(111). The initial remnant polarisation of the un‐doped PZT capacitors was larger than that of PXZT.
Lyapunov‐based adaptive model predictive control for unconstrained non‐linear systems with parametric uncertainties
Authors: Zhu Bing , Xia Xiaohua
Published: June 2016

In this study, a simple Lyapunov‐based adaptive model predictive control (MPC) is proposed to stabilise a class of unconstrained non‐linear systems with constant parametric uncertainties. In the proposed MPC design, the uncertain parameters are estimated online with an adaptive updating law, and the estimated parameters are guaranteed bounded. A Lyapunov‐based constraint is employed in the adaptive MPC to ensure the stability of the closed‐loop system. By using the control Lyapunov function‐based constraint, terminal penalties in traditional MPC can be avoided, such that computational burden is significantly reduced. Both theoretical results and numerical examples demonstrate that, with the proposed adaptive MPC, states of the closed‐loop system can be stabilised, while the adaptive estimated parameters are bounded.
Method for radial vibration modelling in switched reluctance motor
Authors: Guo Xiaoqiang , Zhong Rui , Zhao Longpan , Yin Jun , Sun Weifeng
Published: June 2016

The wide application of switched reluctance motor has been limited due to its high acoustic noise, which is mainly caused by radial vibration. In this study, a new radial vibration model is proposed consisting of vibration acceleration impulse model and natural oscillation model. The vibration acceleration impulse model is developed based on the measured sample data using least‐square support vector machine method. Natural oscillation model is also proposed based on the superposition of each frequency, which is obtained by finite element method. The vibration model is built up in MATLAB/Simulink and various experiments have been conducted to verify the accuracy of the proposed model.
Dynamic equivalent model of VSC based on singular perturbation
Authors: Yuan Zheng , Du Zhengchun , Li Chongtao , An Ting
Published: June 2016

Scalable and computationally efficient model of voltage source converter (VSC) that accurately captures the dynamics is key to the modelling, analysis and control of VSC–high‐voltage direct current system. In this study, a dynamic equivalent model of VSC including the dynamics of control system is obtained by using singular perturbation method for the first time. The reduced second‐order model with simple form and good generality captures the steady‐state and transient behaviours of original full model with a high degree of accuracy. This equivalent model retains the physical meaning of the variables, accommodates different control modes and significantly reduces the computational burden compared with the original full model. Singular perturbation method itself contains some systematic procedures to be able to improve the accuracy of the dynamic behaviour of the lower‐order model. The ability of the dynamic equivalent model to accurately describe the original dynamics of the system has been verified with numerical simulations in normal operation and on fault case associated with MTDC grids.
Development and application of a model‐based collaborative analysis and design framework for microgrid power systems
Authors: Zhu Wanlu , Shi Jian , Liu Sheng , Abdelwahed Sherif
Published: June 2016

Microgrids have been recognised as essential components of the smart grid. However, recent advances on communication, control, and other intelligent techniques have also significantly increased the design complexity of the microgrids. This calls for attention for the microgrid community to be aware of the latest design challenges and develop visionary approaches to re‐evaluate the legacy power system design concepts and analysis tools that are currently utilised for microgrid studies. This study proposes a novel model‐based analysis and design framework tailored specifically for microgrids based on the concept of model‐integrated computing. The proposed framework aims to provide a flexible and extensible integrated environment to facilitate rapid modelling and simulation of microgrids as well as the implementation of other control, analysis, and microgrid design applications. In this study, the authors focus on demonstrating and examining how the adoption of the proposed framework can effectively reduce the duration and costs of the design process, enhance the experience of the end‐users, and improve the overall quality and efficiency of the microgrid study activities. Case studies under various microgrid operating scenarios are presented to validate the effectiveness of the proposed framework.
Transient stability enhancement control of power systems with time‐varying constraints
Authors: Fan Bo , Yang Qinmin , Wang Keyou , Xu Jin , Sun Youxian
Published: June 2016

Transient control performance of power systems is extremely important, especially during the recovery stage from a system temporary fault. A large power angle error or generator relative speed could result in unrecoverable failure or system damage. In this study, a class of novel excitation controllers is proposed for power systems to place user‐defined time‐varying constraints on the system errors. First, the direct feedback linearisation technique is employed to transfer the original non‐linear system to a linear one. An error transformation method is introduced to generate a new non‐linear system, whose stability ensures that the time‐varying constraints on the original system are satisfied. Thus, a backstepping‐based excitation control methodology is designed for ideal case by assuming all system parameters are known. Thereafter, the uncertainties of system dynamics are also considered and compensated by designing an adaptive excitation controller. By utilising the standard Lyapunov synthesis, the closed‐loop system is proved to be asymptotically stable, and all the other signals are bounded for the two control schemes. Furthermore, the system transient performance can be shaped arbitrarily with predefined trajectories, in the sense that the system errors never cross certain boundaries during transient phase. Eventually, extensive simulation studies demonstrate the feasibility of the theoretical results.
S‐shaped droop control method with secondary frequency characteristics for inverters in microgrid
Authors: Li Jun , Li Fangxing , Li Xianyun , Liu Haitao , Chen Fan , Liu Bailiang
Published: June 2016

Microgrid technologies have been studied for various goals including enabling renewable energy penetration. Traditional droop control is important for microgrids to achieve plug and play characteristics, but it may not be suitable for storage units with time‐varying capacity levels due to the constant slope in droop control. In order to address the potential challenges of dynamic adjustment in linear droop control applied to microgrid inverters powered by limited energy sources, this study presents an S‐shaped droop control. This control method tends to make the inverter to output more power when the frequency is close to the nominal operating point, while outputting less power when the frequency is away from the nominal operating point such that the other generators will pick up more load. Also, power quality problems can be addressed with the improvement provided by the characteristic similar to the secondary frequency control which brings the frequency closer to the rated frequency. The proposed mathematical model is built by curve fitting and theoretic analysis, and is simulated in Matlab/Simulink. The results verified the ability to improve power quality and adjust the load share among inverters as opposed to conventional droop control.
Planar quasi‐Yagi antenna with band rejection based on dual dipole structure for UWB
Authors: Yang Deqiang , Qu Jiafeng , Zhao Zhiqin , Liu Sihao , Nie Zaiping
Published: June 2016

Aiming to realise an end‐on‐fire antenna with band rejection for ultra‐wideband (UWB) system, a planar quasi‐Yagi antenna with dual‐dipole structure is proposed. The antenna comprises of a coupling transition structure, two stripes and a dual‐dipole connected by a coplanar stripline. The compact arrangement of the dual‐dipole generates reverse currents at some specific frequency points on their edges, giving rise to phase offsets in far field. This mechanism is used to design band rejection. Simulated and measured results show that the proposed antenna has a bandwidth from 3.08 to 11.1 GHz, which covers the whole UWB band. Meanwhile, the antenna achieves a band rejection from 5.12 to 6.08 GHz, which avoids wireless local area network interference. In pass‐band, the antenna achieves a moderate gain, from 4.6 to 7.1 dBi.
Contact duration aware cache refreshing for mobile opportunistic networks
Authors: Wang Fang , Wang Zhaocheng , Yang Zhixing , Chen Sheng
Published: June 2016

Caching is a practical data access approach in mobile opportunistic networks, which enables mobile terminals to obtain data from adjacent nodes and to reduces accessing latency, whereby the updating files should be delivered to the caching nodes on time when the source is refreshed in order to maintain the freshness of the cached data. Due to the node mobility and short communication range, the contact duration in mobile opportunistic networks is short and this limits the amount of data transmitted in one contact. However, current cache refreshing schemes often ignore this critical issue. In this study, the authors study the contact duration aware cache refreshing in mobile opportunistic networks. Specifically, they establish a two‐state Markov chain to describe the data delivered from one node to another. Based on the proposed model, they investigate a tree structure to refresh the cached data, where each node is responsible to refresh the data cached at its children and it may opportunistically rely on some relays outside the tree to improve the refreshing efficiency. Extensive trace‐driven simulations validate the effectiveness of the authors’ scheme in terms of improving cache refreshing in challenging mobile environments.
Zero DC voltage ride through of a hybrid modular multilevel converter in HVDC systems
Authors: Lu Maozeng , Hu Jiabing , Lin Lei , Xu Kecheng
Published: June 2016

This study presents a comprehensive analysis and a suppression method of sub‐modules’ (SMs’) voltage stress in the hybrid modular multilevel converters when riding through zero DC voltage faults in high‐voltage direct‐current (HVDC) systems. First, the general DC fault ride through (FRT) strategy considering the redundancy of the arm voltage generation scheme under a reduced dc‐link voltage is derived. Then full‐bridge sub‐modules (FBSMs’) voltage stress for the conventional DC‐FRT schemes with and without common‐mode voltage injection are analysed. Finally, on the basis of the available full‐bridge SM capacitor energy control strategy, an improved method implemented by energy interaction between half‐bridge sub‐modules and FBSMs is presented. The proposed DC‐FRT scheme can make all SM capacitor voltages balanced at their rated values during the zero DC voltage conditions. Simulated results are provided to demonstrate the validity of the analytical results and the feasibility of the proposed DC‐FRT scheme.
Bias change detection‐based sensor selection approach for target tracking in large‐scale distributed sensor networks
Authors: Guo Junjun , Yuan Xianghui , Han Chongzhao
Published: June 2016

In large‐scale distributed sensor networks, in the presence of the possible changing sensor biases, this study proposes a bias change detection‐based sensor selection (SS) approach to address this multi‐sensor target tracking problem. The authors only need to detect the bias change and select those reliable sensors (sensors with constant biases) for data fusion, rather than the traditional approach, which try to directly estimate the changing biases. The proposed method mainly contains the following three steps. First, the sliding window marginalised likelihood ratio test algorithm is proposed to detect the bias change. Then based on the bias change detection results, they adopt an SS strategy to select those reliable sensors. Finally, for these selected distributed sensors, the federated filter algorithm is used here for target tracking and bias registration. Simulation results show the effectiveness of these algorithms.
4-Amino-1-allenylsilanes from 4-Aminopropargylic Acetates through a Silylzincation/Elimination Sequence
Authors: Bochatay Valentin , Neouchy Zeina , Chemla Fabrice , Ferreira Franck , Jackowski Olivier , Pérez-Luna Alejandro
Published: June 2016

4-Aminopropargylic acetates afford 4-amino-1-allenylsilanes upon reaction with the lithium (triorganosilyl)zincate (PhMe2Si)3ZnLi. The reaction is both stereoselective and stereospecific and proceeds through syn-silylzincation of the carbon–carbon triple bond followed by subsequent anti-β-elimination of the acetate group.
Collision-induced rotational excitation in N2+(2Σg+,v=)–Ar: Comparison of computations and experiment
Authors: Unke Oliver T. , Castro-Palacio Juan Carlos , Bemish Raymond J. , Meuwly Markus
Published: June 2016

The collisional dynamics of N2+(2Σg+) cations with Ar atoms is studied using quasi-classical simulations. N2+–Ar is a proxy to study cooling of molecular ions and interesting in its own right for molecule-to-atom charge transfer reactions. An accurate potential energy surface (PES) is constructed from a reproducing kernel Hilbert space (RKHS) interpolation based on high-level ab initio data. The global PES including the asymptotics is fully treated within the realm of RKHS. From several ten thousand trajectories, the final state distribution of the rotational quantum number of N2+ after collision with Ar is determined. Contrary to the interpretation of previous experiments which indicate that up to 98% of collisions are elastic and conserve the quantum state, the present simulations find a considerably larger number of inelastic collisions which supports more recent findings.
A simple method to prevent hard X-ray-induced preheating effects inside the cone tip in indirect-drive fast ignition implosions
Authors: Liu Dongxiao , Shan Lianqiang , Zhou Weimin , Wu Yuchi , Zhu Bin , Peng Xiaoshi , Xu Tao , Wang Feng , Zhang Feng , Bi Bi , Zhang Bo , Zhang Zhimeng , Shui Min , He Yingling , Yang Zhiwen , Chen Tao , Chen Li , Chen Ming , Yang Yimeng , Yuan Yongteng , Wang Peng , Gu Yuqiu , Zhang Baohan
Published: June 2016

During fast-ignition implosions, preheating of inside the cone tip caused by hard X-rays can strongly affect the generation and transport of hot electrons in the cone. Although indirect-drive implosions have a higher implosion symmetry, they cause stronger preheating effects than direct-drive implosions. To control the preheating of the cone tip, we propose the use of indirect-drive fast-ignition targets with thicker tips. Experiments carried out at the ShenGuang-III prototype laser facility confirmed that thicker tips are effective for controlling preheating. Moreover, these results were consistent with those of 1D radiation hydrodynamic simulations.
Interaction between bubble and air-backed plate with circular hole
Authors: Liu Y. L. , Wang S. P. , Zhang A. M.
Published: June 2016

This paper investigates the nonlinear interaction between a violent bubble and an air-backed plate with a circular hole. A numerical model is established using the incompressible potential theory coupled with the boundary integral method. A double-node technique is used to solve the overdetermined problem caused by the intersection between the solid wall and the free surface. A spark-generated bubble near the air-backed plate with a circular hole is observed experimentally using a high-speed camera. Our numerical results agree well with the experimental results. Both experimental and numerical results show that a multilevel spike emerges during the bubble’s expansion and contraction. Careful numerical simulation reveals that this special type of spike is caused by the discontinuity in the boundary condition. The influences of the hole size and depth on the bubble and spike dynamics are also analyzed.
Excitation of THz hybrid modes in an elliptical dielectric rod waveguide with a cold collisionless unmagnetized plasma column by an annular electron beam
Authors: Rahmani Z. , Heidari-Semiromi E. , Safari S.
Published: June 2016

The dispersion relation of electromagnetic waves propagating in an elliptical plasma waveguide with a cold collisionless unmagnetized plasma column and a dielectric rod is studied analytically. The frequency spectrum of the hybrid waves and the growth rate for excitation of the waves by a thin annular relativistic elliptical electron beam (TAREEB) is obtained. The effects of relative permittivity constant of dielectric rod, geometrical dimensions, plasma frequency, accelerating voltage, and current density of TAREEB on the growth rate and frequency spectra of the waveguide will be investigated.
Modeling the viscosity of polydisperse suspensions: Improvements in prediction of limiting behavior
Authors: Mwasame Paul M. , Wagner Norman J. , Beris Antony N.
Published: June 2016

The present study develops a fully consistent extension of the approach pioneered by Farris [“Prediction of the viscosity of multimodal suspensions from unimodal viscosity data,” Trans. Soc. Rheol. 12, 281–301 (1968)] to describe the viscosity of polydisperse suspensions significantly improving upon our previous model [P. M. Mwasame, N. J. Wagner, and A. N. Beris, “Modeling the effects of polydispersity on the viscosity of noncolloidal hard sphere suspensions,” J. Rheol. 60, 225-240 (2016)]. The new model captures the Farris limit of large size differences between consecutive particle size classes in a suspension. Moreover, the new model includes a further generalization that enables its application to real, complex suspensions that deviate from ideal non-colloidal suspension behavior. The capability of the new model to predict the viscosity of complex suspensions is illustrated by comparison against experimental data.
Nonlinear gyrokinetic theory and its application to computation of the gyrocenter motion in ripple field
Authors: Zhu Siqiang , Xu Yingfeng , Wang Shaojie
Published: June 2016

The nonlinear gyrokinetic equation with full electromagnetic potential perturbations is derived by using the two-step transform procedure. The second-order transformed Hamiltonian can be simplified as 12δA∥2, instead of 12δA2 in the long-wave-length limit. A numerical code based on the I-transform method is improved to compute the gyrocenter orbit in the TFTR tokamak with a ripple field, and the numerical results indicate that the collisionless stochastic diffusion criterion agrees well with the theoretical prediction.
Ion temperature profiles in front of a negative planar electrode studied by a one-dimensional two-fluid model
Authors: Gyergyek T. , Kovačič J.
Published: June 2016

Plasma-wall transition is studied by a one-dimensional steady state two-fluid model. Continuity and momentum exchange equations are used for the electrons, while the continuity, momentum exchange, and energy transport equation are used for the ions. Electrons are assumed to be isothermal. The closure of ion equations is made by the assumption that the heat flux is zero. The model equations are solved for potential, ion and electron density, and velocity and ion temperature as independent variables. The model includes coulomb collisions between ions and electrons and charge exchange collisions between ions and neutral atoms of the same species and same mass. The neutral atoms are assumed to be essentially at rest. The model is solved for finite ratio ε=λDL between the Debye length and λD and ionization length L in the pre-sheath and in the sheath at the same time. Charge exchange collisions heat the ions in the sheath and the pre-sheath. Even a small increase of the frequency of charge exchange collisions causes a substantial increase of ion temperature. Coulomb collisions have negligible effect on ion temperature in the pre-sheath, while in the sheath they cause a small cooling of ions. The increase of ε causes the increase of ion temperature. From the ion density and temperature profiles, the polytropic function κ is calculated according to its definition given by Kuhn et al. [Phys. Plasmas 13, 013503 (2006)]. The obtained profiles of κ indicate that the ion flow is isothermal only in a relatively narrow region in the pre-sheath, while close to the sheath edge and in the sheath it is closer to adiabatic. The ion sound velocity is space dependent and exhibits a maximum. This maximum indicates the location of the sheath edge only in the limit ε→0.
Tetrahedrality and hydrogen bonds in water
Authors: Székely Eszter , Varga Imre K. , Baranyai András
Published: June 2016

We carried out extensive calculations of liquid water at different temperatures and pressures using the BK3 model suggested recently [P. T. Kiss and A. Baranyai, J. Chem. Phys. 138, 204507 (2013)]. In particular, we were interested in undercooled regions to observe the propensity of water to form tetrahedral coordination of closest neighbors around a central molecule. We compared the found tetrahedral order with the number of hydrogen bonds and with the partial pair correlation functions unfolded as distributions of the closest, the second closest, etc. neighbors. We found that contrary to the number of hydrogen bonds, tetrahedrality changes substantially with state variables. Not only the number of tetrahedral arrangements increases with lowering the pressure, the density, and the temperature but the domain size of connecting tetrahedral structures as well. The difference in tetrahedrality is very pronounced between the two sides of the Widom line and even more so between the low density amorphous (LDA) and high density amorphous (HDA) phases. We observed that in liquid water and in HDA, the 5th water molecule, contrary to ice and LDA, is positioned between the first and the second coordination shell. We found no convincing evidence of structural heterogeneity or regions referring to structural transition.
Non-modal theory of the kinetic ion temperature gradient driven instability of plasma shear flows across the magnetic field
Authors: Mikhailenko V. V. , Mikhailenko V. S. , Lee Hae June
Published: June 2016

The temporal evolution of the kinetic ion temperature gradient driven instability and of the related anomalous transport of the ion thermal energy of plasma shear flow across the magnetic field is investigated analytically. This instability develops in a steady plasma due to the inverse ion Landau damping and has the growth rate of the order of the frequency when the ion temperature is equal to or above the electron temperature. The investigation is performed employing the non-modal methodology of the shearing modes which are the waves that have a static spatial structure in the frame of the background flow. The solution of the governing linear integral equation for the perturbed potential displays that the instability experiences the non-modal temporal evolution in the shearing flow during which the unstable perturbation becomes very different from a canonical modal form. It transforms into the non-modal structure with vanishing frequency and growth rate with time. The obtained solution of the nonlinear integral equation, which accounts for the random scattering of the angle of the ion gyro-motion due to the interaction of ions with ensemble of shearing waves, reveals similar but accelerated process of the transformations of the perturbations into the zero frequency structures. It was obtained that in the shear flow the anomalous ion thermal conductivity decays with time. It is a strictly non-modal effect, which originates from the temporal evolution of the shearing modes turbulence.
Control globular structure formation of a copolymer chain through inverse design
Authors: Yang Xi , Lu Zhong-Yuan
Published: June 2016

A copolymer chain in dilute solution can exhibit various globular structures with characteristic morphologies, which makes it a potentially useful candidate for artificial materials design. However, the chain has a huge conformation space and may not naturally form the globular structure we desire. An ideal way to control globular structure formation should be inverse design, i.e., starting from the target structure and finding out what kind of polymers can effectively generate it. To accomplish this, we propose an inverse design procedure, which is combined with Wang-Landau Monte Carlo to fully and precisely explore the huge conformation space of the chain. Starting from a desired target structure, all the geometrically possible sequences are exactly enumerated. Interestingly, reasonable interaction strengths are obtained and found to be not specified for only one sequence. Instead, they can be combined with many other sequences and also achieve a relatively high yield for target structure, although these sequences may be rather different. These results confirm the possibility of controlling globular structure formation of a copolymer chain through inverse design and pave the way for targeted materials design.
Conceptual moderator studies for the Spallation Neutron Source short-pulse second target station
Authors: Gallmeier F. X. , Lu W. , Riemer B. W. , Zhao J. K. , Herwig K. W. , Robertson J. L.
Published: June 2016

Candidate moderator configurations for a short-pulse second target station (STS) at the Oak Ridge National Laboratory Spallation Neutron Source (SNS) have been identified using a global optimizer framework built around the MCNPX particle transport code. Neutron brightness metrics were selected as the figure-of-merit. We assumed that STS would use one out of six proton pulses produced by an SNS accelerator upgraded to operate at 1.3 GeV proton energy, 2.8 MW power and 60 Hz repetition rate. The simulations indicate that the peak brightness can be increased by a factor of 5 and 2.5 on a per proton pulse basis compared to the SNS first target station for both coupled and decoupled para-hydrogen moderators, respectively. Additional increases by factors of 3 and 2 were demonstrated for coupled and decoupled moderators, respectively, by reducing the area of neutron emission from 100 × 100 mm2 to 20 × 20 mm2. This increase in brightness has the potential to translate to an increase of beam intensity at the instruments’ sample positions even though the total neutron emission of the smaller moderator is less than that of the larger. This is especially true for instruments with small samples (beam dimensions). The increased fluxes in the STS moderators come at accelerated poison and de-coupler burnout and higher radiation-induced material damage rates per unit power, which overall translate into lower moderator lifetimes. A first effort was undertaken to group decoupled moderators into a cluster collectively positioning them at the peak neutron production zone in the target and having a three-port neutron emission scheme that complements that of a cylindrical coupled moderator.
The super- and sub-critical effects for dielectric constant in diethyl ether
Authors: Drozd-Rzoska Aleksandra , Rzoska Sylwester J.
Published: June 2016

Results of dielectric constant (ε) studies in diethyl ether for the surrounding of the gas – liquid critical point, TC − 130 K < T < TC + 50 K, are presented. The analysis recalls the physics of critical phenomena for portraying ε (T) evolution along branches of the coexistence curve, along its diameter (d(T)) and in the supercritical domain for T > TC. For the ultrasound sonicated system, the split into coexisting phases disappeared and dielectric constant approximately followed the pattern of the diameter. This may indicate the possibility of the extension of the “supercritical technology” into the ultrasound “homogenized” subcritical domain: the “strength” and the range of the precritical effect of d(T) are ca. 10× larger than for ε (T > TC).
Determining Curie temperature of (Ga,Mn)As samples based on electrical transport measurements: Low Curie temperature case
Authors: Kwiatkowski Adam , Gryglas-Borysiewicz Marta , Juszyński Piotr , Przybytek Jacek , Sawicki Maciej , Sadowski Janusz , Wasik Dariusz , Baj Michał
Published: June 2016

In this paper, we show that the widely accepted method of the determination of Curie temperature (TC) in (Ga,Mn)As samples, based on the position of the peak in the temperature derivative of the resistivity, completely fails in the case of non-metallic and low-TC unannealed samples. In this case, we propose an alternative method, also based on electric transport measurements, which exploits temperature dependence of the second derivative of the resistivity upon magnetic field.
Mid-infrared concentration-modulated noise-immune cavity-enhanced optical heterodyne molecular spectroscopy of a continuous supersonic expansion discharge source
Authors: Talicska Courtney N. , Porambo Michael W. , Perry Adam J. , McCall Benjamin J.
Published: June 2016

Concentration-modulated noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) is implemented for the first time on a continuous gas-flow pinhole supersonic expansion discharge source for the study of cooled molecular ions. The instrument utilizes a continuous-wave optical parametric oscillator easily tunable from 2.5 to 3.9 μm and demonstrates a noise equivalent absorption of ∼1 × 10−9 cm−1. The effectiveness of concentration-modulated NICE-OHMS is tested through the acquisition of transitions in the ν1 fundamental band of HN2+ centered near 3234 cm−1, with a signal-to-noise of ∼40 obtained for the strongest transitions. The technique is used to characterize the cooling abilities of the supersonic expansion discharge source itself, and a Boltzmann analysis determines a rotational temperature of ∼29 K for low rotational states of HN2+. Further improvements are discussed that will enable concentration-modulated NICE-OHMS to reach its full potential for the detection of molecular ions formed in supersonic expansion discharges.
Optical anisotropy in type-II ZnTe/ZnSe submonolayer quantum dots
Authors: Ji H. , Dhomkar S. , Wu R. , Shuvayev V. , Deligiannakis V. , Tamargo M. C. , Ludwig J. , Lu Z. , Smirnov D. , Wang A. , Kuskovsky I. L.
Published: June 2016

Linearly polarized photoluminescence is observed for type-II ZnTe/ZnSe submonolayer quantum dots (QDs). The comparison of spectral dependence of the degree of linear polarization (DLP) among four samples indicates that the optical anisotropy is mostly related to the elongation of ZnTe QDs. Numerical calculations based on the occupation probabilities of holes in px and py orbitals are performed to estimate the lateral aspect ratio of the QDs, and it is shown that it varies between 1.1 and 1.4. The value of anisotropic exchange splitting for bright excitonic states is found to be ∼200 μeV from the measurement of the degree of circular polarization as a function of the magnetic field. The results also show that heavy-light hole mixing ratio is about 0.16.
Ellipsometric investigation of nitrogen doped diamond thin films grown in microwave CH4/H2/N2 plasma enhanced chemical vapor deposition
Authors: Ficek Mateusz , Sankaran Kamatchi J. , Ryl Jacek , Bogdanowicz Robert , Lin I-Nan , Haenen Ken , Darowicki Kazimierz
Published: June 2016

The influence of N2 concentration (1%–8%) in CH4/H2/N2 plasma on structure and optical properties of nitrogen doped diamond (NDD) films was investigated. Thickness, roughness, and optical properties of the NDD films in the VIS–NIR range were investigated on the silicon substrates using spectroscopic ellipsometry. The samples exhibited relatively high refractive index (2.6 ± 0.25 at 550 nm) and extinction coefficient (0.05 ± 0.02 at 550 nm) with a transmittance of 60%. The optical investigation was supported by the molecular and atomic data delivered by Raman studies, bright field transmission electron microscopy imaging, and X-ray photoelectron spectroscopy diagnostics. Those results revealed that while the films grown in CH4/H2 plasma contained micron-sized diamond grains, the films grown using CH4/H2/(4%)N2 plasma exhibited ultranano-sized diamond grains along with n-diamond and i-carbon clusters, which were surrounded by amorphous carbon grain boundaries.
Compositional dependence of the band-gap of Ge1−x−ySixSny alloys
Authors: Wendav Torsten , Fischer Inga A. , Montanari Michele , Zoellner Marvin Hartwig , Klesse Wolfgang , Capellini Giovanni , von den Driesch Nils , Oehme Michael , Buca Dan , Busch Kurt , Schulze Jörg
Published: June 2016

The group-IV semiconductor alloy Ge1−x−ySixSny has recently attracted great interest due to its prospective potential for use in optoelectronics, electronics, and photovoltaics. Here, we investigate molecular beam epitaxy grown Ge1−x−ySixSny alloys lattice-matched to Ge with large Si and Sn concentrations of up to 42% and 10%, respectively. The samples were characterized in detail by Rutherford backscattering/channeling spectroscopy for composition and crystal quality, x-ray diffraction for strain determination, and photoluminescence spectroscopy for the assessment of band-gap energies. Moreover, the experimentally extracted material parameters were used to determine the SiSn bowing and to make predictions about the optical transition energy.
Fabrication and evaluation of thin layer PVDF composites using MWCNT reinforcement: Mechanical, electrical and enhanced electromagnetic interference shielding properties
Authors: Bhaskara Rao B. V. , Kale Nikita , Kothavale B. S. , Kale S. N.
Published: June 2016

Radar X-band electromagnetic interference shielding (EMS) is one of the prime requirements for any air vehicle coating; with limitations on the balance between strength and thickness of the EMS material. Nanocomposite of multiwalled-carbon-nanotubes (MWCNT) has been homogeneously integrated (0 – 9 wt%) with polymer, poly (vinylidene fluoride, PVDF) to yield 300 micron film. The PVDF + 9 wt% MWCNT sample of density 1.41 g/cm3 show specific shielding effectiveness (SSE) of 17.7 dB/(g/cm3) (99.6% EMS), with maintained hardness and improved conductivity. With multilayer stacking (900 microns) of these films of density 1.37 g/cm3, the sample showed increase in SSE to 23.3 dB/(g/cm3) (99.93% EMS). Uniform dispersion of MWCNTs in the PVDF matrix gives rise to increased conductivity in the sample beyond 5 wt% MWCNT reinforcement. The results are correlated to the hardness, reflection loss, absorption loss, percolation threshold, permittivity and the conductivity data. An extremely thin film with maximum EMS property is hence proposed.