bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly enantioselective copper(i)-catalyzed conjugate addition of 1,3-diynes to α,β-unsaturated trifluoromethyl ketones
Authors: Sanz-Marco Amparo , Blay Gonzalo , Muñoz M. Carmen , Pedro José R.
Published: April 2015

The conjugate diynylation of α,β-unsaturated trifluoromethyl ketones with terminal diynes is carried out. Pre-metalation of the terminal 1,3-diyne is not required. Diynes bearing a propargylic stereogenic center are obtained with good yields and ee's.
Chloride triggered reversible switching from a metallosupramolecular [Pd2L4]4+ cage to a [Pd2L2Cl4] metallo-macrocycle with release of endo- and exo-hedrally bound guests
Authors: Preston Dan , Fox-Charles Alyssa , Lo Warrick K. C. , Crowley James D.
Published: April 2015

A metallosupramolecular [Pd2L4]4+ cage can be cleanly, and reversibly, converted into a [Pd2L2Cl4] metallo-macrocycle upon addition or removal of chloride ions.
Real-time monitoring of the mitophagy process by a photostable fluorescent mitochondrion-specific bioprobe with AIE characteristics
Authors: Zhang Weijie , Kwok Ryan T. K. , Chen Yilong , Chen Sijie , Zhao Engui , Yu Chris Y. Y. , Lam Jacky W. Y. , Zheng Qichang , Tang Ben Zhong
Published: April 2015

A tetraphenylethene-based AIE bioprobe is developed for mitochondrial imaging. The probe shows high brightness, tolerance to environmental changes and photostability, making it promising for monitoring of mitophagy process.
Synergy and pinning effects in a monatomic liquid film in confined conditions
Authors: Wu Weikang , Zhang Leining , Ren Hongru , Zhang Kun , Li Hui , He Yezeng
Published: April 2015

A semi-ordered morphology with maze-like nano-patterns emerges due to the synergy effect and pinning effect of local icosahedral order during rapid cooling.
First principles potential for the cytosine dimer
Authors: Manukyan Artür , Tekin Adem
Published: April 2015

A new first principles potential for the cytosine dimer.
Structural fluctuation governed dynamic diradical character in pentacene
Authors: Yang Hongfang , Chen Mengzhen , Song Xinyu , Bu Yuxiang
Published: April 2015

Energy field-induced structural fluctuation can not only induce potential diradical character but also modulate its dynamical behavior in pentacene.
Experimental determination of the rate of V–V collisional relaxation in14N2in its ground (X1Σg+) electronic state between 77 and 300 K
Authors: Martínez R. Z. , Bermejo D.
Published: April 2015

Selectiveorthopopulation pumping followed by monitoring of the evolution of theortho : pararatio yields vibrational relaxation rate constants.
Phosphorene as an anode material for Na-ion batteries: a first-principles study
Authors: Kulish Vadym V. , Malyi Oleksandr I. , Persson Clas , Wu Ping
Published: April 2015

We present a theoretical study on phosphorene as an anode material for Na-ion batteries.
Single-molecule spectroscopy and femtosecond transient absorption studies on the excitation energy transfer process in ApcE(1–240) dimers
Authors: Long Saran , Zhou Meng , Tang Kun , Zeng Xiao-Li , Niu Yingli , Guo Qianjin , Zhao Kai-Hong , Xia Andong
Published: April 2015

The red-shifted absorption of ApcE dimers results from extending chromophore conformation, which does not depend on strong exction coupling.
Recent advances and new concepts for the synthesis of axially stereoenriched biaryls
Authors: Wencel-Delord J. , Panossian A. , Leroux F. R. , Colobert F.
Published: April 2015

Over the past decade the field of the synthesis of axially chiral compounds has been rapidly expanding. Not only key advances have been achieved concerning the already established strategies but also new synthetic routes have been devised. This review showcases the recent developments in this domain.
Efficient one-pot synthesis of trans-Pt(ii)(salicylaldimine)(4-picoline)Cl complexes: effective agents for enhanced expression of p53 tumor suppressor genes
Authors: Rahman Faiz-Ur , Ali Amjad , Guo Rong , Wang Wei-Kun , Wang Hui , Li Zhan-Ting , Lin Yuejian , Zhang Dan-Wei
Published: April 2015

One-pot synthesizedtrans-Pt(ii)(salicylaldimine)(4-picoline)Cl complexes showed promisingin vitrocytotoxicity in MCF-7 and A549 cancer cell lines.
Chemopreventive activity of ellagitannins and their derivatives from black raspberry seeds on HT-29 colon cancer cells
Authors: Cho Hyunnho , Jung Hana , Lee Heejae , Yi Hae Chang , Kwak Ho-kyung , Hwang Keum Taek
Published: April 2015

Cell cycle arrest and apoptosis were induced by black raspberry seed ellagitannins and their metabolites, ellagic acid and urolithins.
Partitioned EDGE devices for high throughput production of monodisperse emulsion droplets with two distinct sizes
Authors: Sahin Sami , Schroën Karin
Published: April 2015

We present a novel microfluidic EDGE (Edge based Droplet GEneration) device with regularly spaced micron-sized partitions, which is aimed at upscaling of o/w emulsion preparation.
Proteomic characterization of the qualitative and quantitative differences in cervical mucus composition during the menstrual cycle
Authors: Grande G. , Milardi D. , Vincenzoni F. , Pompa G. , Biscione A. , Astorri A. L. , Fruscella E. , De Luca A. , Messana I. , Castagnola M. , Marana R.
Published: April 2015

The chemical composition of the cervical mucus (CM), its physical characteristics and the volume of secretion change cyclically throughout the menstrual cycle.
Palladium-catalysed oxidative cross-esterification between two alcohols
Authors: Xia Jianhui , Shao Ailong , Tang Shan , Gao Xinlong , Gao Meng , Lei Aiwen
Published: April 2015

Oxidative cross-esterification between two alcohols was achieved by using PdCl2(PPh3)2 as the sole catalyst and benzyl chloride as the oxidant.
Pd-complex driven formation of single-chain nanoparticles
Authors: Willenbacher Johannes , Altintas Ozcan , Trouillet Vanessa , Knöfel Nicolai , Monteiro Michael J. , Roesky Peter W. , Barner-Kowollik Christopher
Published: April 2015

The preparation and in-depth characterization of well-defined, palladium(ii) crosslinked single-chain nanoparticles (Pd-SCNPs) is reported. In addition, a novel procedure for interpreting the SEC chromatograms of SCNPs by log-normal distribution (LND) simulations is introduced.
Acid-labile polyrotaxane exerting endolysosomal pH-sensitive supramolecular dissociation for therapeutic applications
Authors: Nishida Kei , Tamura Atsushi , Yui Nobuhiko
Published: April 2015

For achieving pH-sensitive dissociation and the subsequent release of threaded cyclic molecules from polyrotaxanes (PRXs) in weakly acidic environments, a novel acid-labile Pluronic/β-cyclodextrin-based PRX bearing ketal linkages was designed and its potential biomedical application was demonstrated.
Photocontrollable induction of supramolecular chirality in achiral side chain Azo-containing polymers through preferential chiral solvation
Authors: Jiang Shunqin , Zhao Yin , Wang Laibing , Yin Lu , Zhang Zhengbiao , Zhu Jian , Zhang Wei , Zhu Xiulin
Published: April 2015

The preferred supramolecular chirality in aggregates of achiral azobenzene-containing polymers by limonene as a chiral transducer is achieved for the first time.
Anomalous variation of electrical transport property and amorphization in dense Alq3
Authors: Ke Feng , Wang Qinglin , Zhang Junkai , Guo Ying , Tan Dayong , Li Yan , Liu Cailong , Han Yonghao , Ma Yanzhang , Chen Xiao-Jia , Chen Bin , Gao Chunxiao
Published: April 2015

The experimental results indicate that the Al–oxine interaction can also be believed to be significant for the electrical transport properties of dense Alq3.
Spongy nitrogen-doped activated carbonaceous hybrid derived from biomass material/graphene oxide for supercapacitor electrodes
Authors: Gharehkhani Samira , Seyed Shirazi Seyed Farid , Pilban Jahromi Siamak , Sookhakian Mehran , Baradaran Saeid , Yarmand Hooman , Ataollahi Oshkour Azim , Kazi Salim Newaz , Basirun Wan Jefrey
Published: April 2015

A nitrogen doped and activated material with spongy-like structure containing a low cost carbon derived from the waste agricultural material and graphene oxide is synthesizedviafacile thermal treatment for supercapacitor applications.
Improved oral bioavailability of novel antithrombotic S002-333 via chitosan coated liposomes: a pharmacokinetic assessment
Authors: Khandelwal Kiran , Pachauri Shakti Deep , Arya Abhishek , Pawar Vivek K. , Joshi Trapti , Dwivedi Pankaj , Ahmad Hafsa , Singh Bupendra , Sharma Komal , Kanojiya Sanjeev , Chourasia Manish K. , Saxena Anil Kumar , Dwivedi Anil Kumar
Published: April 2015

S002-333, a novel anti-thrombotic agent, exhibits excellent platelet mediated antithrombotic action and subsequently has no effect on the coagulation cascade.
The Aharonov–Bohm effect in the carbon nanotube ring
Authors: Chen Huawei , Zhang Erhu , Zhang Kai , Zhang Shengli
Published: April 2015

The Aharonov–Bohm oscillations of the persistent current and the energy gap are investigated with consideration of the bond length dependent hopping parameters.
Facile one-step synthesis of Co(OH)2 microsphere/graphene composites for an efficient supercapacitor electrode material
Authors: Du Guixiang , Liu PanPan , Yang Xinhui , Zhang Jingbo , Wang Xiaoxu , Sun Xueshan
Published: April 2015

A simple one-step hydrothermal method is developed for the synthesis of flower-like Co(OH)2 microspheres/graphene composites, which exhibit an excellent electrochemical performance.
UV-guided isolation of polyynes and polyenes from the roots of Codonopsis pilosula
Authors: Chao Chih-Hua , Juang Shin-Hun , Chan Hsiu-Hui , Shen De-Yang , Liao Yu-Ren , Shih Hung-Cheng , Huang Chieh-Hung , Cheng Ju-Chien , Chen Fu-An , Hung Hsin-Yi , Wu Tian-Shung
Published: April 2015

UV-guided isolation of polyacetylenes fromCodonopsis pilosulahas successfully led to the characterization of new polyynes and polyenes. The HCVcc infection assay was used to evaluate the anti-HCV activity of compounds1–12.
In situ electrochemical characterisation of graphene and various carbon-based electrode materials: an internal standard approach
Authors: Brownson Dale A. C. , Kelly Peter J. , Banks Craig E.
Published: April 2015

An internal standard protocol is utilised to simultaneously characterise and utilise carbon-based electrode materials during their implementation.
Control and modelling of capillary flow of epoxy resin in aligned carbon nanotube forests
Authors: Beard J. D. , Rouholamin D. , Farmer B. L. , Evans K. E. , Ghita O. R.
Published: April 2015

Modelling and control of resin infiltration into aligned nanotubes allows fabrication of nanocomposite microstructures which could reinforce 3D printed designs.
Tolbutamide induces conformational change and promotes albumin glycation
Authors: Bansode Sneha B. , Batkulwar Kedar B. , Warkad Shrikant D. , Jana Asis K. , Sengupta Neelanjana , Kulkarni Mahesh J.
Published: April 2015

Tolbutamide induces conformational change and promotes albumin glycation.
Nature of reactant and influence of water on the supramolecular patterns and luminescent properties of organic salts comprising (1,1′-biphenyl)-4,4′-disulfonate and triphenylmethanaminium
Authors: Li Ya-Nan , Huo Li-Hua , Deng Zhao-Peng , Xie Xin-Yu , Zhu Zhi-Biao , Gao Shan
Published: April 2015

Fourteen supramolecular compounds have been obtained by the reaction of 1,1′-biphenyl-4,4′-disulfonic acid and triphenylmethylamine, which exhibit seven types of packing diagram in view of the nature of reactant and influence of water.
Novel hybrid epoxy silicone materials as efficient anticorrosive coatings for mild steel
Authors: Suleiman Rami , Dafalla Hatim , El Ali Bassam
Published: April 2015

Novel hybrid organic–inorganic coatings were successfully prepared, coated on mild steel, and subjected to different spectral, electrochemical and morphological characterizations.
An environmentally friendly process for the synthesis of an fGO modified anion exchange membrane for electro-membrane applications
Authors: Sharma Prem P. , Gahlot Swati , Bhil Batuk M. , Gupta Hariom , Kulshrestha Vaibhav
Published: April 2015

We report the synthesis of an anion exchange membrane (AEM) based on chemically covalently modified graphene oxide (GO) for electrodialysis and fuel cell applications.
Coumarin-modified gold nanoprobes for the sensitive detection of caspase-3
Authors: Wang Qiong , Hu Wenqin , Feng Qingyue , Cao Xiu-Hui , Chai Weiwei , Yi Changqing , Li Mei-Jin
Published: April 2015

A coumarin-functionalized gold nanosensor connected to polypeptide chains was developed for the sensitive detection of caspase-3 based on a FRET process.
Photoelectric properties of reduced-graphene-oxide film and its photovoltaic application
Authors: He Hang , Yu Xuegong , Wu Yichao , Zhu Haiyan , Mu Xinhui , Yang Deren
Published: April 2015

An efficiency of 3.36% has been achieved for the graphene/silicon solar cell based on low-cost reduced graphene oxide film.
Microwave-assisted surface-initiated redox polymerization of acrylamide with functionalized graphene oxide for aqueous lubricant additive
Authors: Kumar Arvind , Behera Babita , Ray Siddharth S.
Published: April 2015

A fast, efficient and greener synthesized FGO-PAM nanocomposite as an improved aqueous lubricating additive.
Ultra-tiny Co(OH)2 particles supported on graphene oxide for highly efficient electrocatalytic water oxidation
Authors: Liu Jiong , Du Fuping , Zhang Haojie , Lin Chao , Gao Peng , Chen Yuyun , Shi Zhifang , Li Xiaopeng , Zhao Tiejun , Sun Yuhan
Published: April 2015

The TOF value of the ultra-tiny Co(OH)2/GO nanocomposite electrocatalyst is 2.7 times higher than that of hydrothermally treated Co3O4/GO.
An enantioselective approach to 2-alkyl substituted tetrahydroquinolines: total synthesis of (+)-angustureine
Authors: Garg Yuvraj , Gahalawat Suraksha , Pandey Satyendra Kumar
Published: April 2015

A simple and highly efficient synthetic approach to enantiopure 2-alkyl substituted tetrahydroquinoline 1 skeleton from aldehydes as starting materials and its application to the total synthesis of (+)-angustureine 2 is described.
DNA-modified graphene quantum dots as a sensing platform for detection of Hg2+in living cells
Authors: Zhao Xin , Gao Jinsuo , He Xin , Cong Longchao , Zhao Huimin , Li Xiaoyu , Tan Feng
Published: April 2015

A facile method for detection of Hg2+in living cells based on DNA modified graphene quantum dots.
Highly selective turn-on detection of (strept)avidin based on self-assembled near-infrared fluorescent probes
Authors: He Qingyuan , Fan Xiaopeng , Sun Shiguo , Li Hongjuan , Pei Yuxin , Xu Yongqian
Published: April 2015

A small molecular fluorescent dye (SQ-Biotin) which can self-assemble into a non-fluorescent probe in aqueous solution for near infrared turn-on detection of avidin protein.
Ultrafiltration modeling of non-ionic microgels
Authors: Roa Rafael , Zholkovskiy Emiliy K. , Nägele Gerhard
Published: April 2015

Solvent permeability of non-ionic microgel particles is an essential ingredient to the ultrafiltration modeling.
ZnO nanorods covered with a TiO2 layer: simple sol–gel preparation, and optical, photocatalytic and photoelectrochemical properties
Authors: Kwiatkowski Maciej , Bezverkhyy Igor , Skompska Magdalena
Published: April 2015

In this work, composite core–shell ZnO/TiO2 materials were fabricated by deposition of TiO2 layers via sol–gel method on ZnO nanorods hydrothermally grown on ITO electrode.
New insight into the electrical properties and ion dynamics of screen printed NASICON thick films
Authors: Mudenda Steven , Kale Girish M.
Published: April 2015

The AC conductivity of NASICON thick films at high temperatures and the relaxation mechanism are independent of film thickness. 7 μm is the minimum thickness that could be printed on alumina substrate and used in high temperature applications.
Black titanium oxide nanoarray electrodes for high rate Li-ion microbatteries
Authors: Eom Ji-Yong , Lim Sung-Jin , Lee Sang-Min , Ryu Won-Hee , Kwon Hyuk-Sang
Published: April 2015

Black TiO2−x nanotube arrays, which are synthesized by an electrochemical method and subsequent thermal conversion in a hydrogen atmosphere, are employed as binder-free, free-standing electrodes for high rate Li-ion microbatteries.
Self-generating graphene and porous nanocarbon composites for capacitive energy storage
Authors: Zhang Haitao , Wang Kai , Zhang Xiong , Lin He , Sun Xianzhong , Li Chen , Ma Yanwei
Published: April 2015

Graphene and porous nanocarbon composites with high specific surface areas and large pore volumes deliver excellent capacitive performances.
Symbolic calculus for class of quantum computing circuits
Authors: Hadjam F.Z. , Moraga C.
Published: April 2015

A symbolic calculus to evaluate the output signals at the target line(s) of quantum computing subcircuits using controlled negations and controlled‐Q gates is introduced, where Q represents the kth root of [0 1; 1 0], the unitary matrix of NOT, and k is a power of two. The controlling signals are GF(2) expressions possibly including Boolean expressions. The method does not require operating with complex‐valued matrices. The method may be used to verify the functionality and to check for possible minimisation of a given quantum computing circuit using target lines. The method does not apply for a whole circuit if there are interactions among target lines. In this case the method applies for the independent subcircuits.
Compressive wideband spectrum sensing based on single channel
Authors: Sun Weichao , Huang Zhitao , Wang Fenghua , Wang Xiang
Published: April 2015

The modulated wideband converter (MWC) is an attractive analogue compressed sensing technique that has been proposed in recent years. Regrettably, the MWC has high hardware complexity owing to its parallel channel structure. To reduce the complexity, a novel compressive wideband spectrum sensing scheme based on a single channel for band‐limited wide‐sense stationary (WSS) signals is proposed. In the proposed scheme, a special periodic waveform in the time domain is designed and a power spectrum sensing model is presented to detect the occupied frequency spectrum of such signals from sub‐Nyquist samples of which the sample rate is only MWC's single‐channel rate. Simulation results show that the proposed scheme has a perfect performance on wideband WSS signal spectrum sensing.
Joint frequency domain equalisation and phase noise estimation for single‐carrier modulations in doubly‐selective channels
Authors: Pedrosa Pedro , Dinis Rui , Nunes Fernando , Rodrigues Antonio
Published: April 2015

In this study the authors propose a novel joint detection and phase noise estimation scheme suited for severely time‐dispersive channels. The authors consider single‐carrier modulations combined with frequency domain equalisation schemes where the wireless transmission is impaired with phase noise. An iterative frequency‐domain equaliser is assumed on the receiver side and the phase noise is estimated and compensated for after the equalisation step and within each iteration of the equaliser. In fact, by exploiting the Gaussianity of the equaliser output the authors are able to track the phase noise using stochastic recursive filtering techniques. These techniques share the same dynamic state‐space (DSS) model. The observation equation corresponds to the measurement of the phase noise of a digitally‐modulated signal affected by additive white Gaussian noise, and the dynamics equation corresponds to the Wiener–Lévy model for the phase noise. Supported on this DSS model the authors aim at estimating the unknown phase noise value given all observations up to the current time instant. In a Bayesian context this represents estimating recursively in time the filtering and the predictive distributions. From these distributions a minimum mean‐squared error estimate of the phase noise is determined.
Design and testing of a compact circularly polarised microstrip antenna with fractal defected ground structure for L‐band applications
Authors: Prajapati Pravin Ratilal , Murthy Gannavarapu Gopala Krishna , Patnaik Amalendu , Kartikeyan Machavaram Venkata
Published: April 2015

A compact circularly polarised (CP) microstrip antenna for mobile satellite communication band of India (1.492–1.518 GHz) is presented. Two asymmetric length rectangular shape slots, perpendicular to each other are printed on the circular patch for realisation of CP radiation. To improve the performance parameters of patch antenna such as axial ratio (AR) bandwidth, return loss bandwidth, radiation efficiency and so on a new technique of combination of fractal theory and defected ground structure (DGS) is proposed for the first time in design of CP antennas. 44.74% size reduction in patch size, enhancements of 62.73% in AR bandwidth, 70.74% in return loss bandwidth and 4.03% in radiation efficiency is achieved as compared with conventional patch antenna, after incorporation of Koch curve fractal DGS in the ground plane. The performance of the developed antenna has been compared with other available L‐band planar antennas in the literature, and it is found that the developed structure is better one in many aspects. Laboratory prototype of the antenna is fabricated and experimentally measured for cross verifying the simulated results.
Dimmable light‐emitting diode driver with cascaded current regulator and voltage source
Authors: Jane Gwan‐Chi , Lin Yu‐Liang , Chiu Huang‐Jen , Lo Yu‐Kang
Published: April 2015

This study presents a dimmable light‐emitting diode (LED) driver consisting of a flyback power factor corrector (PFC) with two secondary windings. The first secondary output is cascaded by a floating buck current regulator with a dimming switch. Then its unregulated output voltage is connected in series with the second secondary output, which acts as a regulated voltage source. Since either secondary output voltage is lower than that of a single‐output topology, low voltage‐rating film capacitors with longer lifetime can be used instead of electrolytic capacitors. Most of the load power is supplied by the voltage source. Therefore the reduced voltage stress and switching losses on the dimming switch result in high conversion efficiency in a wide dimming range. The operating principles and design considerations of the proposed LED driver are discussed and analysed. A 20‐W laboratory prototype with dimming feature is developed and tested. Satisfactory experimental results verify the feasibility of the studied driver.
Position sensorless surface‐mounted permanent‐magnet synchronous generator and its application to power DC microgrid
Authors: Hu Kai‐Wei , Liaw Chang‐Ming
Published: April 2015

This study presents a position sensorless surface‐mounted permanent‐magnet synchronous generator (SPMSG) and its application in powering DC microgrid. The derated characteristics of a PMSG with different AC–DC converters under brushless DC generator (BDCG) mode and the conventional switch‐mode rectifier (SMR) mode are first comparatively assessed. Then a PMSG followed by three‐phase three‐switch Vienna SMR is established. Good operation performance is achieved via the proposed robust current and voltage control schemes. Second, a position sensorless control scheme based on observed extended back electromotive force (EMF) for the SPMSG followed by Vienna SMR is developed. The generation characteristics are enhanced by the developed starting and back‐EMF angle tuning schemes. Third, a single‐phase three‐wire load inverter with the proposed novel robust waveform tracking control scheme is developed to yield good AC 220 V/110 V output voltage waveforms under unknown and non‐linear loads. Some experimental results are provided to demonstrate the operation performances of the established SPMSG system in conventional generator with fixed output voltage and wind generator. More specifically, the BDCG mode and the SMR mode for operating a PMSG are experimentally evaluated.
Analysis and modelling of circulating current in two parallel‐connected inverters
Authors: Maheshwari Ramkrishan , Gohil Ghanshyamsinh , Bede Lorand , Munk‐Nielsen Stig
Published: April 2015

Parallel‐connected inverters are gaining attention for high power applications because of the limited power handling capability of the power modules. Moreover, the parallel‐connected inverters may have low total harmonic distortion of the ac current if they are operated with the interleaved pulse‐width modulation (PWM). However, the interleaved PWM causes a circulating current between the inverters, which in turn causes additional losses. A model describing the dynamics of the circulating current is presented in this study which shows that the circulating current depends on the common‐mode voltage. Using this model, the circulating current between two parallel‐connected inverters is analysed in this study. The peak and root mean square (rms) values of the normalised circulating current are calculated for different PWM methods, which makes this analysis a valuable tool to design a filter for the circulating current. The peak and rms values of the circulating current are plotted for different PWM methods, and a discontinuous PWM is identified which offers the minimum peak and rms value of the circulating current. Experimental results are presented to verify the analysis.
Generalised approach for predictive control with common‐mode voltage mitigation in multilevel diode‐clamped converters
Authors: Yaramasu Venkata , Wu Bin , Rivera Marco , Narimani Mehdi , Kouro Samir , Rodriguez Jose
Published: April 2015

This study proposes a generalised approach based on model predictive strategy for the current control, dc‐link capacitor voltages balancing, switching frequency reduction and common‐mode voltage mitigation in multilevel diode‐clamped converters. A generalised discrete‐time model of the converters is presented, where all the control objectives are formulated in terms of the switching states. The control goals are expressed as a cost function, and with the help of suitable weighting factors these goals are met simultaneously. The cost function minimisation is used as criteria for choosing the best switching state which would be applied to the converter during next sampling interval. The real‐time digital control issues such as computational burden and delay compensation are also discussed. The feasibility of the proposed method is verified by simulations in three‐ to six‐level converters, and by experiments in three‐ and four‐level converters.
High step‐up DC–DC converter based on the switched‐coupled‐inductor boost converter and diode‐capacitor multiplier: steady state and dynamics
Authors: Axelrod Boris , Beck Yuval , Berkovich Yefim
Published: April 2015

In this study a new scheme of a step‐up converter with very high voltage gain is proposed. The scheme is based on a natural combination of the switched‐coupled‐inductor boost converter and the diode‐capacitor multiplier. The study proposes a special scheme of their mutual use for attaining very high voltage gain. An important advantage of the proposed circuit is the avoidance of the current spikes through the transistor and diodes because of the leakage inductance of the coupled inductors. The scheme provides soft commutation of the switch and the diodes. The study analyses the modes of operation and obtains the basic fundamental relations in steady state; an expression for voltage stress across the switch is derived. A new method for dynamic analysis is proposed. The corresponding analytical expressions and curves of the transient behaviour are also obtained. Modelling of the proposed structure and the experimental results are in full agreement regarding the expected efficiency and correctness of the theoretical analysis. A 100 W laboratory prototype was built and verified.
Robust optimal current control for grid‐connected three‐phase pulse‐width modulated converters
Authors: Maccari Luiz Antonio , Amaral Santini Claudio Luiz do , Pinheiro Humberto , de Oliveira Ricardo C.L.F. , Montagner Vinícius Foletto
Published: April 2015

This study deals with the current control of three‐phase inverters connected to the grid by means of LCL filters. The control action is given by the feedback of the filter states, in coordinates αβ0, and of the internal states of resonant controllers. The control gains are computed by means of an optimal linear quadratic regulator that is robust to uncertain and time‐varying parameters related to the grid impedance at the point of common coupling. As contributions, one has the detailed proof of a robust discrete linear quadratic control, showing its applicability also for the time‐varying case, the experimental validation of the results in terms of the total harmonic distortion and harmonic limits for the grid injected current, according to the IEEE 1547 standard, and the analysis of the ℋ∞ norm of the closed‐loop system for several values of grid inductance, indicating a value of grid inductance for which one has best performance for the time‐invariant case. For comparison, a conventional state feedback controller is designed and implemented, showing the limitation of the non‐robust strategy.
Sliding mode harmonic compensation strategy for power quality improvement of a grid‐connected inverter under distorted grid condition
Authors: Kang Sung‐Wook , Kim Kyeong‐Hwa
Published: April 2015

A novel sliding mode harmonic compensation (SMHC) scheme is proposed for the enhanced power quality in distributed generation systems under distorted grid condition. The harmonic pollution caused by non‐linear loads in electrical networks brings about distorted grid voltage, power losses and heating in electrical equipments. The proposed SMHC scheme is composed of a harmonic detector and a sliding mode harmonic current controller based on the integral sliding mode control. By using the fourth order band pass filter, the proposed harmonic detector can effectively extract harmonic components without phase delay. These harmonic components can be notably suppressed by adopting the sliding mode harmonic current controller with fast dynamic response. Whereas the conventional sliding mode schemes have been developed to control the entire current value, the proposed SMHC scheme controls only the harmonic components by dividing inverter voltage model into the fundamental and harmonic models. Since the fundamental component in charge of power flow is controlled by proportional‐integral controller, the chattering can be quite reduced. The proposed scheme is a non‐selective harmonic compensation, which reduces the computational burden than the conventional selective schemes. The validity of the proposed scheme is demonstrated through simulations and experiments using 2 kVA laboratory prototype grid‐connected inverter.
Thermal/mechanical properties of short carbon fibre/SiC co‐reinforced graphite matrix composites produced by low temperature hot pressing
Authors: Han Yongjun , Yan Qingzhi , Li Xianhui
Published: April 2015

Short carbon fibre and silicon carbide (SiC) co‐reinforced graphite matrix composites were prepared with natural flaky graphite as raw materials by low temperature hot pressing at 1900°C. The flexural strength in the direction perpendicular to the graphite layers reached 221 MPa for carbon fibre of 5 vol% and SiC of 30 vol%, which was an improvement of 275% compared with pure graphite materials. The composites improved the bend strength of the block obviously, while maintaining the thermal conductivity of 220 W/m K in the direction perpendicular to the hot pressing. The new process has the advantages of being a non‐pitch binder process which avoids the high temperature graphitisation operation.
Silicon‐on‐insulator‐based microsolid propellant thruster array
Authors: Shen Qiang , Yuan Wei Zheng , Li He , Xie Jian Bing , Chang Hong Long
Published: April 2015

A silicon‐on‐insulator (SOI)‐based microelectromechanical system solid propellant thruster array is presented. The micronozzle layer and microigniter layer of the array are formed on both surfaces of the SOI wafer, respectively. The layout design rules can properly distribute the heat produced by the microigniter below the solid propellant inside the chamber. Test results show that the highest temperature of the microigniter is located under the propellant. When one unit in the array is ignited by a DC voltage of 7.9 V, other units around it are not ignited. Moreover, the ignition resistors can work again, which means that the array can be used repeatedly when the solid propellant is refilled.
Performance improvement of organic solar cells with the introduction of branched zinc oxide nanorods
Authors: Wei Fanan , Jiang Minlin , Zhou Lei , Dong Zaili
Published: April 2015

Zinc oxide (ZnO) nanorods with branches are synthesised through facile hydrothermal approach at relatively low temperature. With the prepared ZnO nanostructures as the hole‐blocking layer, organic solar cells based on poly(3‐hexylthiophene): 1‐(3‐methoxycarbonyl)propyl‐1‐phenyl[6,6]C61 are fabricated. For comparison, devices with planar ZnO thin film and bare ZnO nanorods are manufactured as well. J –V curves show that the best device performance is achieved by the branched nanorod‐based solar cell. Owing to the decreased charge carrier travelling length, the nanorod‐based device shows higher short circuit current (Jsc) than that of the device with planar ZnO layer. Moreover, the solar cell with branched nanorods shows larger open‐circuit voltage (Voc) than that with bare nanorods. Therefore, the performance of organic photovoltaic is enhanced with the introduction of branched ZnO nanorods. Finally, the mechanism of device performance improvement upon the introduction of branched nanorods is discussed.
Das intraoperative CT
Authors: Hoffmann Christoph-H. , Wilde Philipp , Hoffmann Reinhard , Kandziora Frank
Published: April 2015

Das intraoperative CT (iCT) ist ein modernes bildgebendes Verfahren in der Wirbelsäulen- und Unfallchirurgie. Eingriffe, die eine hohe Präzision erfordern, sind für den Einsatz der spinalen Navigation auf Grundlage intraoperativer CT-Bildgebung besonders geeignet. Hierzu zählen die korrekte transpedikuläre Schraubenplatzierung bei schmalen Pedikeln, intraossäre Tumoren, ausgeprägte Deformitäten, Revisionseingriffe und myelonnahe bzw. intramedulläre Operationen im Bereich der Wirbelsäulenchirurgie. Unfallchirurgische Indikationen bestehen v. a. bei Beckeneingriffen sowie bei der operativen Versorgung komplexer Gelenkverletzungen. Das intraoperative CT ermöglicht eine zeitnahe Kontrolle des Operationsergebnisses mit einer höheren Bildqualität sowie einem wesentlich größeren Field of View im Vergleich zur intraoperativen 3D-Fluoroskopie. Die Strahlenbelastung ist für den Patienten höher als beim fluoroskopischen Verfahren, für den Operateur jedoch geringer. Die Kosteneffektivität des iCTs sowie der iCT-gestützten Navigation ist aufgrund der noch immer hohen Investitionskosten niedrig, unter medizinischen Aspekten ist das iCT-gestützte Navigieren jedoch gegenüber anderen Monitoringverfahren klinisch oftmals vorteilhaft.
Control of wire heating with resistively guided fast electrons through an inverse conical taper
Authors: Robinson A. P. L. , Schmitz H. , Green J. S. , Ridgers C. P. , Booth N. , Pasley J.
Published: April 2015

The heating of a solid wire embedded in a solid substrate (of lower Z material) with relativistic electrons generated by ultra-intense laser irradiation is considered. Previously, it has been noted that the initial angular distribution of the fast electrons is a highly important factor in the efficacy of the heating [Robinson et al., Phys. Plasmas 20, 122701 (2013)]. We show that, using 3D numerical simulations, the addition of an inverse conical taper at the front of wire can considerably improve the heating of the wire due to the reduction of angular spread of the fast electrons which is caused by transport through the inverse conical taper [Robinson et al., “Guiding of laser-generated fast electrons by exploiting the resistivity-gradients around a conical guide element,” Plasma Phys. Controlled Fusion (to be published)].
Tomography based numerical simulation of the demagnetizing field in soft magnetic composites
Authors: Arzbacher S. , Amann P. , Weidenfeller B. , Loerting T. , Ostermann A. , Petrasch J.
Published: April 2015

The magneto-static behaviour of soft magnetic composites (SMCs) is investigated using tomography based direct numerical simulation. The microgeometry crucially affects the magnetic properties of the composite since a geometry dependent demagnetizing field is established inside the composite, which lowers the magnetic permeability. We determine the magnetic field information inside the SMC using direct numerical simulation of the magnetic field based on high resolution micro-computed tomography data of the SMC's microstructure as well as artificially generated data made of statistically homogeneous systems of identical fully penetrable spheres and prolate spheroids. Quasi-static electromagnetic behaviour and linear material response are assumed. The 3D magnetostatic Maxwell equations are solved using Whitney finite elements. Simulations show that clustering and percolation behaviour determine the demagnetizing factor of SMCs rather than the particle shape. The demagnetizing factor correlates with the slope of a 2-point probability function at its origin, which is related to the specific surface area of the SMC. Comparison with experimental results indicates that the relatively low permeability of SMCs cannot be explained by demagnetizing effects alone and suggests that the permeability of SMC particles has to be orders of magnitude smaller than the bulk permeability of the particle material.
A novel monolithic piezoelectric actuated flexure-mechanism based wire clamp for microelectronic device packaging
Authors: Liang Cunman , Wang Fujun , Tian Yanling , Zhao Xingyu , Zhang Hongjie , Cui Liangyu , Zhang Dawei , Ferreira Placid
Published: April 2015

A novel monolithic piezoelectric actuated wire clamp is presented in this paper to achieve fast, accurate, and robust microelectronic device packaging. The wire clamp has compact, flexure-based mechanical structure and light weight. To obtain large and robust jaw displacements and ensure parallel jaw grasping, a two-stage amplification composed of a homothetic bridge type mechanism and a parallelogram leverage mechanism was designed. Pseudo-rigid-body model and Lagrange approaches were employed to conduct the kinematic, static, and dynamic modeling of the wire clamp and optimization design was carried out. The displacement amplification ratio, maximum allowable stress, and natural frequency were calculated. Finite element analysis (FEA) was conducted to evaluate the characteristics of the wire clamp and wire electro discharge machining technique was utilized to fabricate the monolithic structure. Experimental tests were carried out to investigate the performance and the experimental results match well with the theoretical calculation and FEA. The amplification ratio of the clamp is 20.96 and the working mode frequency is 895 Hz. Step response test shows that the wire clamp has fast response and high accuracy and the motion resolution is 0.2 μm. High speed precision grasping operations of gold and copper wires were realized using the wire clamper.
Dopant controlled trap-filling and conductivity enhancement in an electron-transport polymer
Authors: Higgins Andrew , Mohapatra Swagat K. , Barlow Stephen , Marder Seth R. , Kahn Antoine
Published: April 2015

Charge transport in organic semiconductors is often inhibited by the presence of tail states that extend into the band gap of a material and act as traps for charge carriers. This work demonstrates the passivation of acceptor tail states by solution processing of ultra-low concentrations of a strongly reducing air-stable organometallic dimer, the pentamethylrhodocene dimer, [RhCp*Cp]2, into the electron transport polymer poly{[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)}, P(NDI2OD-T2). Variable-temperature current-voltage measurements of n-doped P(NDI2OD-T2) are presented with doping concentration varied through two orders of magnitude. Systematic variation of the doping parameter is shown to lower the activation energy for hopping transport and enhance film conductivity and electron mobility.
Synchrotron-based double imaging photoelectron/photoion coincidence spectroscopy of radicals produced in a flow tube: OH and OD
Authors: Garcia Gustavo A. , Tang Xiaofeng , Gil Jean-François , Nahon Laurent , Ward Michael , Batut Sebastien , Fittschen Christa , Taatjes Craig A. , Osborn David L. , Loison Jean-Christophe
Published: April 2015

We present a microwave discharge flow tube coupled with a double imaging electron/ion coincidence device and vacuum ultraviolet (VUV) synchrotron radiation. The system has been applied to the study of the photoelectron spectroscopy of the well-known radicals OH and OD. The coincidence imaging scheme provides a high selectivity and yields the spectra of the pure radicals, removing the ever-present contributions from excess reactants, background, or secondary products, and therefore obviating the need for a prior knowledge of all possible byproducts. The photoelectron spectra encompassing the X3Σ− ground state of the OH+ and OD+ cations have been extracted and the vibrational constants compared satisfactorily to existing literature values. Future advantages of this approach include measurement of high resolution VUV spectroscopy of radicals, their absolute photoionization cross section, and species/isomer identification in chemical reactions as a function of time.
Polarisabilities of long conjugated chain molecules with density functional response methods: The role of coupled and uncoupled response
Authors: Heßelmann Andreas
Published: April 2015

The longitudinal component of the dipole-dipole polarisability of polyacetylene molecules containing 4 to 20 carbon atoms has been calculated with density-functional theory (DFT) response methods. In order to analyse the effect of the uncoupled and coupled contributions to the response matrix, a number of different sets of orbitals were combined with different approximations for the Hessian matrix. This revealed a surprising result: a qualitatively correct increase of the polarisability with the chain length can already be reproduced on the uncoupled level if the response matrix is constructed from Hartree-Fock (HF) or exact-exchange (EXX) DFT orbitals. The nonlocal HF and the local EXX exchange potentials both produce a displacement of charge from the chain ends to the centre of the polyacetylene molecule compared to DFT methods using standard exchange-correlation potentials. In this way, the reduced increase of the transition dipole moments along the molecular axis counteracts the decrease of the occupied-virtual orbital energy gaps and leads to a linear dependence of the polarisabilities (normalised by the number of carbon atoms) on the chain length. A new DFT response approach is tested which utilises unitary transformed Hartree-Fock orbitals as input and which resolves the failure of standard DFT response methods.
Theory of the jamming transition at finite temperature
Authors: DeGiuli E. , Lerner E. , Wyart M.
Published: April 2015

A theory for the microscopic structure and the vibrational properties of soft sphere glass at finite temperature is presented. With an effective potential, derived here, the phase diagram and vibrational properties are worked out around the Maxwell critical point at zero temperature T and pressure p. Variational arguments and effective medium theory identically predict a non-trivial temperature scale T∗ ∼ p(2−a)/(1−a) with a ≈ 0.17 such that low-energy vibrational properties are hard-sphere like for T ≳ T∗ and zero-temperature soft-sphere like otherwise. However, due to crossovers in the equation of state relating T, p, and the packing fraction ϕ, these two regimes lead to four regions where scaling behaviors differ when expressed in terms of T and ϕ. Scaling predictions are presented for the mean-squared displacement, characteristic frequency, shear modulus, and characteristic elastic length in all regions of the phase diagram.
Local magnetic structure determination using polarized neutron holography
Authors: Szakál Alex , Markó Márton , Cser László
Published: April 2015

A unique and important property of the neutron is that it possesses magnetic moment. This property is widely used for determination of magnetic structure of crystalline samples observing the magnetic components of the diffraction peaks. Investigations of diffraction patterns give information only about the averaged structure of a crystal but for discovering of local spin arrangement around a specific (e.g., impurity) nucleus remains still a challenging problem. Neutron holography is a useful tool to investigate the local structure around a specific nucleus embedded in a crystal lattice. The method has been successfully applied experimentally in several cases using non-magnetic short range interaction of the neutron and the nucleus. A mathematical model of the hologram using interaction between magnetic moment of the atom and the neutron spin for polarized neutron holography is provided. Validity of a polarized neutron holographic experiment is demonstrated by applying the proposed method on model systems.
Scaling effects in ohmic contacts on semiconductors
Authors: Ruzin A.
Published: April 2015

This article reports on scaling effects calculated with ohmic contacts on various types of high and low resistivity semiconductors, from near-intrinsic to heavily compensated. The investigation was performed using a finite element computation. It is shown that small ohmic contacts exhibit Schottky-like energy band diagrams on compensated and uncompensated semiconductors. It is shown that the currents of ideal ohmic contacts scale with the contact's perimeter below critical contact size and with area for larger contacts. Bulk velocity saturation effect is shown to introduce non-linearity and asymmetry in the current-voltage characteristics even for ideal ohmic contacts. The effect of finite contact recombination velocity is analyzed. In compensated semiconductors, the deep level carrier capture cross-sections have no effect on resistivity, but may play an important role in the device dc characteristics.
A seven-degree-of-freedom, time-dependent quantum dynamics study on the energy efficiency in surmounting the central energy barrier of the OH + CH3 → O + CH4 reaction
Authors: Yan Pengxiu , Wang Yuping , Li Yida , Wang Dunyou
Published: April 2015

A time-dependent, quantum reaction dynamics calculation with seven degrees of freedom was carried out to study the energy efficiency in surmounting the approximate center energy barrier of OH + CH3. The calculation shows the OH vibration excitations greatly enhance the reactivity, whereas the vibrational excitations of CH3 and the rotational excitations hinder the reactivity. On the basis of equal amount of total energy, although this reaction has a slight early barrier, it is the OH vibrational energy that is the dominate force in promoting the reactivity, not the translational energy. The studies on both the forward O + CH4 and reverse OH + CH3 reactions demonstrate, for these central barrier reactions, a small change of the barrier location can significantly change the energy efficacy roles on the reactivity. The calculated rate constants agree with the experimental data.
Magnetodielectric and magnetoviscosity response of a ferromagnetic liquid crystal at low magnetic fields
Authors: Sahoo Rasmita , Rasna M. V. , Lisjak D. , Mertelj A. , Dhara Surajit
Published: April 2015

We report on experimental studies of the viscoelastic, magnetodielectric, and magnetoviscosity properties of ferromagnetic liquid crystals (LCs) prepared by dispersing ferromagnetic nanoparticles in a thermotropic LC. Both the splay elastic constant and rotational viscosity of the ferronematic LCs are found to be considerably lower than that of the pure LC and advantageous to the device applications. The ferromagnetic LCs show unique magnetodielectric and magnetoviscosity response at very low magnetic fields that are useful for smart fluid applications.