bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxidation and temperature dual responsive polymers based on phenylboronic acid and N-isopropylacrylamide motifs
Authors: Zhang Mei , Song Cheng-Cheng , Ji Ran , Qiao Zeng-Ying , Yang Chao , Qiu Fang-Yi , Liang De-Hai , Du Fu-Sheng , Li Zi-Chen
Published: January 2016

Oxidation and temperature dual responsive copolymers using ROS as a target for drug delivery have been demonstrated.
Improved biomass production by humic analog anthraquinone-2-sulfonate from kitchen waste in a two-phase system
Authors: Wang Xingzu , Xu Guihua , Wan Chunli , Ren Yiwei , Tian Enling
Published: January 2016

The volatile fatty acids from kitchen waste were used as substrates of anoxygenic photosynthetic bacteria (APB) in a dark-photo fermentation reactor, and anthraquinone-2-sulfonate (AQS) was firstly applied to boost the biomass yield.
Synthesis and biological evaluation of novel hybrid compounds between chalcone and piperazine as potential antitumor agents
Authors: Mao Zewei , Zheng Xi , Qi Yan , Zhang Mengdi , Huang Yao , Wan Chunping , Rao Gaoxiong
Published: January 2016

A series of novel hybrid compounds between chalcone and piperazine have been synthesized, and their in vitro antitumor activity was evaluated against a panel of human tumor cell lines by MTT assay.
Textile/Al2O3–TiO2 nanocomposite as an antimicrobial and radical scavenger wound dressing
Authors: Parham Shokoh , Chandren Sheela , Wicaksono Dedy H. B. , Bagherbaigi Saeedeh , Lee Siew Ling , Yuan Lai Sin , Nur Hadi
Published: January 2016

Improving the antimicrobial activity and radical scavenging ability of a textile-based nanocomposite is the key issue in developing a good and flexible wound dressing.
Preparation and characterization of antibacterial paper coated with sodium lignosulfonate stabilized ZnO nanoparticles
Authors: Pang Bo , Yan Jipeng , Yao Lan , Liu Huan , Guan Jing , Wang Haisong , Liu Huizhou
Published: January 2016

The ZnO nanoparticles were synthesized using sodium lignosulfonate as a stabilizing agent and sodium hydroxide as a precipitation agent. The negatively charged ZnO nanoparticles were deposited onto cellulose paper through a layer-by-layer approach.
Side-chain shuffling: regioselective synthesis of mixed tail discotic mesogens
Authors: Voisin Emilie , Williams Vance E.
Published: January 2016

A procedure for the regioselective synthesis of discotic mesogens bearing multiple side chains of different lengths is reported.
Responses of ammonia-oxidizing bacteria community composition to temporal changes in physicochemical parameters during food waste composting
Authors: Shi Shanshan , Zou Dexun , Wang Qunhui , Xia Xunfeng , Zheng Tianlong , Wu Chuanfu , Gao Ming
Published: January 2016

This paper aimed to identify and prioritize some environmental parameters that affect AOB community composition during food waste composting.
Enhancement of BLIS production by Pediococcus acidilactici kp10 in optimized fermentation conditions using an artificial neural network
Authors: Abbasiliasi Sahar , Tan Joo Shun , Kadkhodaei Saeid , Nelofer Rubina , Tengku Ibrahim Tengku Azmi , Mustafa Shuhaimi , Ariff Arbakariya B.
Published: January 2016

The present study was aimed at enhancing the production of BLIS produced byPediococcus acidilacticiKp10 through optimizing the fermentation parameters.
Arrangements of enantiopure and racemic ionic liquids at the liquid/air interface: the role of chirality on self-assembly and layering
Authors: Caporali S. , Chiappe C. , Ghilardi T. , Iuliano A. , Longhi G. , Margari P. , Pomelli C. S.
Published: January 2016

This paper reports on the self-assembly ability at the interface IL/air for some couples of enantiopure and racemic chiral ILs.
Construction and functional effects of a compatible nano-TiO2interface between wood fiber and polypropylene via adopting chemical polyethyleneimine–(3-aminopropyl) triethoxysilane assembly on the fiber surface
Authors: Ye Xianzhu , Wang Hua , Zheng Kang , Wu Zhaofeng , Zhou Haifeng , Tian Xingyou
Published: January 2016

A simple chemical assembly to construct a compatible nano-TiO2-coating on a wood surface has been reported using polyethyleneimine and (3-aminopropyl) triethoxysilane for recycled wood–polypropylene composites (WPCs).
Regulation of acidogenic metabolism towards enhanced short chain fatty acid biosynthesis from waste: metagenomic profiling
Authors: Sarkar Omprakash , Kumar A. Naresh , Dahiya Shikha , Krishna K. Vamshi , Yeruva Dileep Kumar , Mohan S. Venkata
Published: January 2016

To enhance short chain carboxylic (volatile fatty) acids production from food waste, the present study evaluates a strategy for selective enrichment of the biocatalyst by exposing it to acid-shock.
Equilibrium and kinetic studies on MB adsorption by ultrathin 2D MoS2nanosheets
Authors: Qiao Xiu-Qing , Hu Fu-Chao , Tian Feng-Yu , Hou Dong-Fang , Li Dong-Sheng
Published: January 2016

MoS2ultrathin nanosheets display excellent adsorption ability towards methylene blue, with a maximum adsorption capacity of 146.43 mg g−1in 300 seconds. Moreover, the adsorbent can be resued by washing with deionized water.
Phase diagram for a nano-yttria-stabilized zirconia system
Authors: Asadikiya Mohammad , Sabarou Hooman , Chen Ming , Zhong Yu
Published: January 2016

A 3-D phase diagram for an n-YSZ system was established in which the stability range of each individual phase can be predicted based on the particle size, composition, and temperature.
Identification of different tumor states in nasopharyngeal cancer using surface-enhanced Raman spectroscopy combined with Lasso-PLS-DA algorithm
Authors: Chen Guannan , Lin Xueliang , Lin Duo , Ge Xiaosong , Feng Shangyuan , Pan Jianji , Lin Juqiang , Huang Zufang , Huang Xi , Chen Rong
Published: January 2016

Identification of different states in cancer is of vital importance for cancer treatment and management.
Up-conversion photoluminescence and temperature sensing properties of Er3+-doped Bi4Ti3O12 nanoparticles with good water-resistance performance
Authors: Wei T. , Zhang T. B. , Ma Y. J. , Xie Y. F. , Zhao C. Z. , Yang F. M. , Xiao H. Y. , Zhao Y.
Published: January 2016

Er3+-doped Bi4Ti3O12 (BiT-x) with different particle sizes were successfully synthesized via a low-cost coprecipitation method without any surfactants.
Design of oxygen sensing nanomaterial: synthesis, encapsulation of phenylacetylide substituted Pd(ii) and Pt(ii) meso-tetraphenylporphyrins into poly(1-trimethylsilyl-1-propyne) nanofibers and influence of silver nanoparticles
Authors: Önal Emel , Ay Zeynep , Yel Zübeyde , Ertekin Kadriye , Gürek Ayşe Gül , Topal Sevinc Zehra , Hirel Catherine
Published: January 2016

Room temperature phosphorescent oxygen sensors have been designed by embedding symmetric palladium(ii) or platinum(ii) meso-tetraphenylporphyrins in poly(1-trimethylsilyl-1-propyne) in the form of nanofibers along with/without silver nanoparticles.
Fuel cell anode catalyst performance can be stabilized with a molecularly rigid film of polymers of intrinsic microporosity (PIM)
Authors: He Daping , Rong Yuanyang , Carta Mariolino , Malpass-Evans Richard , McKeown Neil B. , Marken Frank
Published: January 2016

There remains a major materials challenge in maintaining the performance of platinum (Pt) anode catalysts in fuel cells due to corrosion and blocking of active sites.
Construction of a bone-like surface layer on hydroxyl-modified carbon/carbon composite implants via biomimetic mineralization and in vivo tests
Authors: Cao Ning , Yang Zhenguo , Yang Bai , Wang Wenbo , Boukherroub Rabah , Li Musen
Published: January 2016

By means of biomimetic mineralization method, Mg-doped hydroxyapatite nano particles were successfully prepared on hydroxyl-modified C/C surfaces.
Metal-free aerobic oxidative coupling of amines in dimethyl sulfoxide via a radical pathway
Authors: Lin Mu , Wang Zikuan , Fang Huayi , Liu Lianghui , Yin Haolin , Yan Chun-Hua , Fu Xuefeng
Published: January 2016

Metal-free oxidative coupling of amines is achieved simply by heating their dimethyl sulfoxide (DMSO) solution under oxygen, accompanied by the formation of an equimolar amount of dimethyl sulfone (DMSO2).
Growth of thiol-coated Au-nanoparticle Langmuir monolayers through a 2D-network of disk-like islands
Authors: Mukhopadhyay Mala , Hazra S.
Published: January 2016

Formation of 2D-networked structures of disk-like islands for ultrathin Langmuir–Schaefer (LS) films of thiol-coated Au-nanoparticles (DT-AuNPs) on H-passivated Si substrates is evidenced for the first time, by X-ray scattering data and AFM images.
Predicting the reducing power of organic super electron donors
Authors: Anderson Greg M. , Cameron Iain , Murphy John A. , Tuttle Tell
Published: January 2016

This work describes an improved, more accurate model for the calculation of electron transfer energetics of organic super electron donors.
Enhanced proton conductivity of multiblock poly(phenylene ether ketone)s via pendant sulfoalkoxyl side chains with excellent H2/air fuel cell performance
Authors: Dong Tiandu , Hu Jiahui , Ueda Mitsuru , Wu Yiming , Zhang Xuan , Wang Lianjun
Published: January 2016

A multi-block compositing graft concept is investigated to fabricate proton exchange membranes. The prepared membranes demonstrate excellent ion conductive capacity and better fuel cell performance over the entire relative humidity conditions, compared to Nafion.
Fluorinated dendrimer for TRAIL gene therapy in cancer treatment
Authors: Wang Yitong , Wang Mingming , Chen Hui , Liu Hongmei , Zhang Qiang , Cheng Yiyun
Published: January 2016

The transfection of tumor necrosis factor-related apoptosis-inducing ligand gene by using fluorinated dendrimer is highly efficient and low toxic, resulting in efficient killing of cancer cells in vitro and suppressing tumor growth in vivo.
H∞ performance realisation and switching controller design for linear time‐invariant plant
Authors: Xie Wei
Published: January 2016

This study focuses on the design of a switching controller, which includes several linear time‐invariant (LTI) controllers designed beforehand and independently, for a specific LTI plant. All of these LTI controllers are capable of stabilising the plant with corresponding H∞ control performance criterions. It is shown that there exist suitable state space realisations of these controller transfer matrices that guarantee not only certain H∞ control performance of the overall closed‐loop system under arbitrary switching but also corresponding H∞ performances of local closed‐loop systems at switching points.
Robust exponential stability and stabilisation of parametric uncertain switched linear systems under arbitrary switching
Authors: Ali Bagherzadeh Mohamad , Ghaisari Jafar , Askari Javad
Published: January 2016

Stability of switched linear systems under arbitrary switching signals is an important requirement, when the switching mechanism is unknown, or too complicated to be useful in the stability analysis. In this study, robust exponential stability and exponential stabilisation of parametric uncertain switched linear systems are investigated under arbitrary switching. First, sufficient conditions are proposed to ensure the existence of a common quadratic Lyapunov function (CQLF) for arbitrary switched linear systems with uncertain parameters belong to known intervals. Then, an estimation of stability intervals for uncertain parameters is provided via a theorem. To enlarge the estimated stability intervals, an offline optimisation algorithm is also proposed. Finally, the derived results for robust exponential stability are used to stabilise the uncertain switched linear systems which are not stable under arbitrary switching signals. For this purpose, a method is proposed to design a single state feedback gain in the way that the closed‐loop switched linear system is robustly exponentially stable under arbitrarily fast switching signals. Numerical examples are included to demonstrate the effectiveness of the results.
Quantisation‐based robust control of uncertain non‐strict‐feedback non‐linear systems under arbitrary switching
Authors: Lai Guanyu , Liu Zhi , Zhang Yun , Philip Chen Chun Lung
Published: January 2016

This study concentrates on the problem of robust quantised control for a class of switched non‐strict‐feedback non‐linear systems under arbitrary switching. Differs from non‐switched non‐linear systems, the stability in switched ones (especially under arbitrary switching) is much dependent on the construction of common Lyapunov function (CLF). However, such CLF is fairly difficult to be designed in this study as the simultaneous consideration of full‐states uncertainties, unknown virtual control coefficients, as well as quantisation problem. To overcome the challenge, this study presents a systematic control design method. Specifically, the neural networks with minimal learning parameter, and the boundedness property of Gaussian basis functions are combined to deal with the full‐states uncertainties, while an online estimator is built by sufficiently using the special structure of virtual controllers to dispose the unknown virtual coefficients problem. Moreover, a non‐linear decomposition of quantiser is further proposed, rendering that the quantisation problem can be solved independently at the last step of backstepping iteration. With these results, an adaptive control algorithm which guarantees a CLF for all subsystems is successfully established such that the tracking error is steered into an adjustable area of origin asymptotically, and meanwhile all closed‐loop signals remain uniformly ultimately bounded under arbitrary switching. Lastly, the obtained conclusions are well verified by the simulated results.
Vibration control strategy for large‐scale structures with incomplete multi‐actuator system and neighbouring state information
Authors: Palacios‐Qui nonero Francisco , Rubió‐Massegú Josep , M. Rossell Josep , Reza Karimi Hamid
Published: January 2016

The synthesis of optimal controllers for vibrational protection of large‐scale structures with multiple actuation devices and partial state information is a challenging problem. In this study, the authors present a design strategy that allows computing this kind of controllers by using standard linear matrix inequality optimisation tools. To illustrate the main elements of the new approach, a five‐story structure equipped with two interstory actuation devices and subjected to a seismic disturbance is considered. For this control setup, three different controllers are designed: an ideal state‐feedback H∞ controller with full access to the complete state information and two static output‐feedback H∞ controllers with restricted neighbouring state information. To assess the performance of the proposed controllers, the corresponding frequency responses are investigated and a proper set of numerical simulations are conducted, using the full scale North‐South El Centro 1940 seismic record as ground acceleration input. The obtained results indicate that, despite the severe information constraints, the proposed static output‐feedback controllers attain a level of seismic protection that is very similar to that achieved by the ideal state‐feedback controller with complete state information.
Event‐triggered fault detection and isolation for discrete‐time linear systems
Authors: Hajshirmohamadi Shahram , Davoodi Mohammadreza , Meskin Nader , Sheikholeslam Farid
Published: January 2016

In this study, the problem of event‐triggered fault detection and isolation (FDI) for discrete‐time linear time‐invariant systems is considered. Using a Leunberger observer as the residual generator, a multi‐objective formulation of the FDI problem is presented based on l1, H _ and H∞ performance indices. For each performance index, sufficient conditions for the design of FDI observer are presented based on linear matrix inequalities (LMIs). To reduce the conservativeness of the multi‐objective problem, extended LMIs are used to eliminate the couplings of Lyapunov matrices with the system state space matrices. It is shown that through an event‐triggered data transmission mechanism, the amount of data that is sent to the FDI module is significantly decreased. Simulation results corresponding to a remotely operated vehicle demonstrate the effectiveness and capabilities of the proposed design methodology.
Region tracking control for high‐order multi‐agent systems in restricted space
Authors: Sun Xiaoming , Sam Ge Shuzhi , Zhang Jun , Cao Xianbin
Published: January 2016

In this study, decentralised region tracking control is proposed to force a group of mobile agents with high‐order non‐linear dynamics to track a moving target region without collisions as well as to avoid the obstacle on the track in restricted space. The decentralised controllers can also guarantee connectivity preserving of the dynamic interaction network. The control design is based on artificial potential functions, neural network (NN) approximation, adaptive backstepping techniques and Lyapunov's method. It is proved that under the adaptive NN control, the tracking error of each agent can converge to an adjustable neighbourhood of the origin, although some of them do not access the desired region directly. Simulation results are represented to illustrate the performance of the proposed approach.
Resolution enhancement of textual images: a survey of single image‐based methods
Authors: Walha Rim , Drira Fadoua , Lebourgeois Frank , Alimi Adel M. , Garcia Christophe
Published: January 2016

Super‐resolution (SR) task has become an important research area due to the rapidly growing interest for high quality images in various computer vision and pattern recognition applications. This has led to the emergence of various SR approaches. According to the number of input images, two kinds of approaches could be distinguished: single or multi‐input based approaches. Certainly, processing multiple inputs could lead to an interesting output, but this is not the case mainly for textual image processing. This study focuses on single image‐based approaches. Most of the existing methods have been successfully applied on natural images. Nevertheless, their direct application on textual images is not enough efficient due to the specificities that distinguish these particular images from natural images. Therefore, SR approaches especially suited for textual images are proposed in the literature. Previous overviews of SR methods have been concentrated on natural images application with no real application on the textual ones. Thus, this study aims to tackle this lack by surveying methods that are mainly designed for enhancing low‐resolution textual images. The authors further criticise these methods and discuss areas which promise improvements in such task. To the best of the authors’ knowledge, this survey is the first investigation in the literature.
Evidence for thermally assisted threshold switching behavior in nanoscale phase-change memory cells
Authors: Le Gallo Manuel , Athmanathan Aravinthan , Krebs Daniel , Sebastian Abu
Published: January 2016

In spite of decades of research, the details of electrical transport in phase-change materials are still debated. In particular, the so-called threshold switching phenomenon that allows the current density to increase steeply when a sufficiently high voltage is applied is still not well understood, even though there is wide consensus that threshold switching is solely of electronic origin. However, the high thermal efficiency and fast thermal dynamics associated with nanoscale phase-change memory (PCM) devices motivate us to reassess a thermally assisted threshold switching mechanism, at least in these devices. The time/temperature dependence of the threshold switching voltage and current in doped Ge2Sb2Te5 nanoscale PCM cells was measured over 6 decades in time at temperatures ranging from 40 °C to 160 °C. We observe a nearly constant threshold switching power across this wide range of operating conditions. We also measured the transient dynamics associated with threshold switching as a function of the applied voltage. By using a field- and temperature-dependent description of the electrical transport combined with a thermal feedback, quantitative agreement with experimental data of the threshold switching dynamics was obtained using realistic physical parameters.
Room temperature magnetoelectric coupling in BaTi1−xCrxO3 multiferroic thin films
Authors: Sundararaj Anuraj , Chandrasekaran Gopalakrishnan , Therese Helen Annal , Annamalai Karthigeyan
Published: January 2016

We report on room temperature (RT) magnetoelectric coupling in tetragonal BaTi1−xCrxO3 thin film multiferroics (BTCO) sputter deposited on (100) SrTiO3 (where x = 0.005, 0.01, 0.02, and 0.03). As-deposited thin films are vacuum annealed by electron beam rapid thermal annealing technique. 50 nm thick BTCO with “x = 0.01” shows RT ferromagnetic and ferroelectric response with saturation magnetic moment of 1120 emu/cc and polarization of 14.7 microcoulomb/cm2. Piezoresponse/magnetic force microscope images shows RT magnetoelectric coupling in BTCO with “x = 0.01,” which is confirmed using magnetocapacitance measurement where an increase in capacitance from 17.5 pF to 18.4 pF is observed with an applied magnetic field.
Charge transport model in solid-state avalanche amorphous selenium and defect suppression design
Authors: Scheuermann James R. , Miranda Yesenia , Liu Hongyu , Zhao Wei
Published: January 2016

Avalanche amorphous selenium (a-Se) in a layer of High Gain Avalanche Rushing Photoconductor (HARP) is being investigated for its use in large area medical imagers. Avalanche multiplication of photogenerated charge requires electric fields greater than 70 V μm−1. For a-Se to withstand this high electric field, blocking layers are used to prevent the injection of charge carriers from the electrodes. Blocking layers must have a high injection barrier and deep trapping states to reduce the electric field at the interface. In the presence of a defect in the blocking layer, a distributed resistive layer (DRL) must be included into the structure to build up space charge and reduce the electric field in a-Se and the defect. A numerical charge transport model has been developed to optimize the properties of blocking layers used in various HARP structures. The model shows the incorporation of a DRL functionality into the p-layer can reduce dark current at a point defect by two orders of magnitude by reducing the field in a-Se to the avalanche threshold. Hole mobility in a DRL of ∼10−8 cm2 V−1 s−1 at 100 V μm−1 as demonstrated by the model can be achieved experimentally by varying the hole mobility of p-type organic or inorganic semiconductors through doping, e.g., using Poly(9-vinylcarbozole) doped with 1%–3% (by weight) of poly(3-hexylthiopene).
Experimental demonstration and modeling of the internal light scattering profile within solar cells due to random dielectric scatterers
Authors: Murray Joseph , Munday Jeremy N.
Published: January 2016

Many photovoltaic technologies are shifting toward thin-film devices to simultaneously reduce costs and improve carrier collection efficiencies; however, the need for nearly complete light absorption within the semiconductor to achieve large short-circuit currents constrains this thickness reduction. Light trapping strategies can be employed to increase absorption in thinner devices. Random scattering coatings offer a simple, cost-effective way to increase solar cell absorption without the drawback of increased surface recombination or reduced bandwidth that occurs when using surface texturing or gratings. However, coatings that show excellent performance as scatterers in free space generally do not enhance device absorption as much as an ideal Lambertian scatterer. Here, we present an experimental technique and theoretical model that accurately describes the absorption improvement that is achievable with coatings based on random ensembles of dielectric scatterers. We find that the ideal Lambertian model substantially overestimates the experimental scattering results, but significant path length enhancements are still achievable. The experimental techniques presented here should enable the testing of various optical models that attempt to surpass the ray optics light trapping limit, which have in many cases been hindered by the experimental difficulty of coupling the incident light into the optical modes of the absorber.
Trapping and patterning of biological objects using photovoltaic tweezers
Authors: Jubera M. , Elvira I. , García-Cabañes A. , Bella J. L. , Carrascosa M.
Published: January 2016

Photovoltaic tweezers are a recently proposed technique for manipulation and patterning of micro- and nano-objects. It is based in the dielectrophoretic forces associated to the electric fields induced by illumination of certain ferroelectrics due to the bulk photovoltaic effect. The technique has been applied to the patterning of dielectric and metal micro- and nano-particles. In this work, we report the use of photovoltaic tweezers to pattern biological objects on LiNbO3:Fe. Specifically, spores and pollen grains and their nanometric fragments have been trapped and patterned. 1D and 2D arrangements have been achieved by deposition in air or from a hexane suspension. The quality of patterns obtained with nanometric fragments is even better than previous results using photovoltaic tweezers with inorganic micro- and nano-particles. In fact, 1D patterns with a period of 2 μm, almost half of the minimum reported period achieved with photovoltaic tweezers, have been obtained with pollen fragments.
Frequency control of a spin-torque oscillator using magnetostrictive anisotropy
Authors: Park Min Gyu Albert , Baek Seung-heon Chris , Park Byong-Guk , Lee Seok-Hee
Published: January 2016

We report the working principle of a spin-torque oscillator, of which the frequency is efficiently controlled by manipulating the magnetostrictive anisotropy. To justify the scheme, we simulate a conventional magnetic-tunnel junction-based oscillator which is fabricated on a piezoelectric material. By applying mechanical stress to a free layer using a piezoelectric material, the oscillation frequency can be controlled to ensure a broad tuning range without a significant reduction of the dynamic resistance variation. Such controllability, which appears in the absence of an external magnetic field, will not only enable the integration of spin-torque oscillators and conventional complimentary metal-oxide semiconductor technology but will also broaden the applicability of spin-torque oscillators.
Site engineering and polarization characteristics in (Ba1−yCay)(Ti1−xHfx)O3 lead-free ceramics
Authors: Zhao Chunlin , Wu Wenjuan , Wang Hui , Wu Jiagang
Published: January 2016

Here we improved both piezoelectricity and strain of BaTiO3-based ceramics using composition designs and the optimization of poling conditions. In this work, the (Ba1−yCay)(Ti1−xHfx)O3 lead-free ceramics were fabricated by a conventional solid-state reaction method, and we systematically investigated the composition dependence of their phase structures, microstructure, electrical properties, and polarization characteristics. A multiphase coexistence concerning rhombohedral-orthorhombic and orthorhombic-tetragonal (R-O/O-T) was observed in the ceramics with x = 0.10 and y = 0.15, and then an enhanced piezoelectricity of d33 ∼ 540 pC N−1 and a large strain of ∼0.21% can be attained. More importantly, a larger d33 can be reached when sintered at 1450 °C and polarized at their corresponding phase transition temperatures. We believe that this investigation can benefit the development of barium titanate ceramics.
Strong influence of non-ideality of electrodes on stability of single domain state in ferroelectric-paraelectric superlattices
Authors: Levanyuk A. P. , Misirlioglu I. B.
Published: January 2016

We study the phase stabilities with respect to small perturbations in ferroelectric-paraelectric superlattices and show that nature of the electrodes characterized by a deviation from the ideal behavior strongly influences the possibility to obtain single-domain state in ferroelectric-paraelectric superlattices. To demonstrate this, we analyze the limit of stability of the paraelectric and the single domain state in ferroelectric-paraelectric superlattices in contact with top and bottom electrodes with finite screening lengths. The combined analytical and numerical analyses of one bilayer and two bilayer systems are carried out using the Landau-Ginzburg-Devonshire formalism and equations of electrostatics. The BaTiO3/SrTiO3 system was considered as an example. Unlike the case of ideal electrodes where the stability limits are independent of the system size, the stability analysis in a multilayer with real electrodes should take into account explicitly the number of the repeating units that makes the algebra very cumbersome, forcing us to consider systems with one and two bilayer stacks only. Extrapolating the difference between the two systems to the cases of many repeating units gives us the possibility to make qualitative but feasible predictions related to those with many repeating units. We observe that in systems with nearly equal thicknesses of the ferroelectric and paraelectric layers, the electrodes with realistic screening lengths lead to dramatic widening of the parametric region where the single-domain state is absolutely unstable expelling the single-domain state to unphysical layer thicknesses and temperatures. This region grows when one goes from a single bilayer to two bilayer system, implying that obtaining a single domain state becomes even less feasible in systems with many bilayers. When electrode properties approach that of ideal in addition to increasing the volume fraction of the ferroelectric component, the effect of growth of the region of absolute instability of the single domain state may remain very strong for relatively thin repeating units (a few nanometers). This tendency will continue with increasing the number of the repeating units.
Protected gates for topological quantum field theories
Authors: Beverland Michael E. , Buerschaper Oliver , Koenig Robert , Pastawski Fernando , Preskill John , Sijher Sumit
Published: January 2016

We study restrictions on locality-preserving unitary logical gates for topological quantum codes in two spatial dimensions. A locality-preserving operation is one which maps local operators to local operators — for example, a constant-depth quantum circuit of geometrically local gates, or evolution for a constant time governed by a geometrically local bounded-strength Hamiltonian. Locality-preserving logical gates of topological codes are intrinsically fault tolerant because spatially localized errors remain localized, and hence sufficiently dilute errors remain correctable. By invoking general properties of two-dimensional topological field theories, we find that the locality-preserving logical gates are severely limited for codes which admit non-abelian anyons, in particular, there are no locality-preserving logical gates on the torus or the sphere with M punctures if the braiding of anyons is computationally universal. Furthermore, for Ising anyons on the M-punctured sphere, locality-preserving gates must be elements of the logical Pauli group. We derive these results by relating logical gates of a topological code to automorphisms of the Verlinde algebra of the corresponding anyon model, and by requiring the logical gates to be compatible with basis changes in the logical Hilbert space arising from local F-moves and the mapping class group.
Influence of CO annealing in metal-oxide-semiconductor capacitors with SiO2 films thermally grown on Si and on SiC
Authors: Pitthan E. , dos Reis R. , Corrêa S. A. , Schmeisser D. , Boudinov H. I. , Stedile F. C.
Published: January 2016

Understanding the influence of SiC reaction with CO, a by-product of SiC thermal oxidation, is a key point to elucidate the origin of electrical defects in SiC metal-oxide-semiconductor (MOS) devices. In this work, the effects on electrical, structural, and chemical properties of SiO2/Si and SiO2/SiC structures submitted to CO annealing were investigated. It was observed that long annealing times resulted in the incorporation of carbon from CO in the Si substrate, followed by deterioration of the SiO2/Si interface, and its crystallization as SiC. Besides, this incorporated carbon remained in the Si surface (previous SiO2/Si region) after removal of the silicon dioxide film by HF etching. In the SiC case, an even more defective surface region was observed due to the CO interaction. All MOS capacitors formed using both semiconductor materials presented higher leakage current and generation of positive effective charge after CO annealings. Such results suggest that the negative fixed charge, typically observed in SiO2/SiC structures, is not originated from the interaction of the CO by-product, formed during SiC oxidation, with the SiO2/SiC interfacial region.
Dynamic range in the C. elegans brain network
Authors: Antonopoulos Chris G.
Published: January 2016

We study external electrical perturbations and their responses in the brain dynamic network of the Caenorhabditis elegans soil worm, given by the connectome of its large somatic nervous system. Our analysis is inspired by a realistic experiment where one stimulates externally specific parts of the brain and studies the persistent neural activity triggered in other cortical regions. In this work, we perturb groups of neurons that form communities, identified by the walktrap community detection method, by trains of stereotypical electrical Poissonian impulses and study the propagation of neural activity to other communities by measuring the corresponding dynamic ranges and Steven law exponents. We show that when one perturbs specific communities, keeping the rest unperturbed, the external stimulations are able to propagate to some of them but not to all. There are also perturbations that do not trigger any response. We found that this depends on the initially perturbed community. Finally, we relate our findings for the former cases with low neural synchronization, self-criticality, and large information flow capacity, and interpret them as the ability of the brain network to respond to external perturbations when it works at criticality and its information flow capacity becomes maximal.
Thermoelectric properties of half-Heusler topological insulators MPtBi (M = Sc, Y, La) induced by strain
Authors: Ding Guangqian , Gao G. Y. , Yu Li , Ni Yun , Yao KaiLun
Published: January 2016

Thermoelectric (TE) materials and topological insulators (TIs) were recently known to exhibit close connection, which offers new prospects in improving the TE performance. However, currently known TE materials from TIs mostly belong to the early Bi2Te3 family. In order to extend TE materials to other classes of TIs, we use the first-principles combined with Boltzmann transport theory to study the electronic and TE properties of experimental half-Heusler compounds MPtBi (M = Sc, Y, La). We find that all MPtBi are topological semimetals at equilibrium lattices while TIs under a stretched uniaxial strain, which is in agreement with previous works. We further predict that comparable TE performance with Bi2Te3 can be realized in half-Heusler TI LaPtBi by an 8% stretched uniaxial strain. We also reveal that the lattice thermal conductivity of LaPtBi is unprecedented low compared with those of traditional half-Heusler compounds (not TIs). These findings indicate the potential of half-Heusler TIs as TE materials.
Correlation of the nanostructure with optoelectronic properties during rapid thermal annealing of Ga(NAsP) quantum wells grown on Si(001) substrates
Authors: Wegele Tatjana , Beyer Andreas , Gies Sebastian , Zimprich Martin , Heimbrodt Wolfram , Stolz Wolfgang , Volz Kerstin
Published: January 2016

Ga(NAsP) quantum wells grown pseudomorphically on Si substrate are promising candidates for optically active light sources in future optoelectronically integrated circuits on Si substrates. As the material is typically grown at low temperatures, it has to be thermally annealed after growth to remove defects and optimize optoelectronic properties. Here we show by quantitative transmission electron microscopy that two different kinds of structural development are associated with the annealing. First of all, the quantum well homogeneity improves with increasing annealing temperature. For annealing temperatures above 925 °C the composition becomes less homogeneous again. Second, voids form in the quantum well for annealing temperatures above 850 °C. Their density and size increase continuously with increasing annealing temperature. These results are correlated to the optical properties of the samples, where we find from temperature-dependent photoluminescence measurements two scales of disorder, which show the same temperature dependence as the structural properties.
Uncertainty quantification in modeling of microfluidic T-sensor based diffusion immunoassay
Authors: Jha Aman Kumar , Bahga Supreet Singh
Published: January 2016

Comparison of experimental data with modeling predictions is essential for making quantitative measurements of species properties, such as diffusion coefficients and species concentrations using a T-sensor. To make valid comparisons between experimental data and model predictions, it is necessary to account for uncertainty in model predictions due to uncertain values of model parameters. We present an analysis of uncertainty induced in model predictions of a T-sensor based competitive diffusion immunoassay due to uncertainty in diffusion constants, binding reaction rate constants, and inlet flow speed. We use a non-intrusive stochastic uncertainty quantification method employing polynomial chaos expansions to represent the dependence of uncertain species concentrations on the uncertainty in model parameters. Our simulations show that the uncertainties in model parameters lead to significant spatially varying uncertainty in predicted concentration. In particular, the diffusivity of fluorescently labeled probe antigen dominates the overall uncertainty. The predicted uncertainty in fluorescence intensity is minimum near the centerline of T-sensor and relatively high in the regions with gradients in fluorescence intensity. We show that using centerline fluorescence intensity instead of first derivative of fluorescence intensity as the system response for measuring sample antigen concentration in T-sensor based competitive diffusion immunoassay leads to lower uncertainty and higher detection sensitivity.
Magnetic field-induced ferroelectric domain structure evolution and magnetoelectric coupling for [110]-oriented PMN-PT/Terfenol-D multiferroic composites
Authors: Fang F. , Jing W. Q.
Published: January 2016

Magnetic field-induced polarization rotation and magnetoelectric coupling effects are studied for [110]-oriented (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3/Tb0.3Dy0.7Fe2(PMN-xPT/Terfenol-D) multiferroic composites. Two compositions of the [110]-oriented relaxor ferroelectric single crystals, PMN-28PT and PMN-33PT, are used. In [110]-oriented PMN-28PT, domains of rhombohedral (R) and monoclinic (MB) phases coexist prior to the magnetic loadings. Upon the applied magnetic loadings, phase transition from monoclinic MB to R phase occurs. In [110]-oriented PMN-33PT, domains are initially of mixed orthorhombic (O) and MB phases, and the phase transition from O to MB phase takes place upon the external magnetic loading. Compared to PMN-28PT, the PMN-33PT single crystal exhibits much finer domain boundary structure prior to the magnetic loadings. Upon the magnetic loadings, more domain variants are induced via the phase transition in PMN-33PT than that in PMN-28PT single crystal. The finer domain band structure and more domain variants contribute to stronger piezoelectric activity. As a result, the composite of PMN-33PT/Terfenol-D manifests a stronger ME coupling than PMN-28PT/Terfenol-D composite.
Numerical solution for Sakiadis flow of upper-convected Maxwell fluid using Cattaneo-Christov heat flux model
Authors: Mushtaq A. , Abbasbandy S. , Mustafa M. , Hayat T. , Alsaedi A.
Published: January 2016

Present work studies the well-known Sakiadis flow of Maxwell fluid along a moving plate in a calm fluid by considering the Cattaneo-Christov heat flux model. This recently developed model has the tendency to describe the characteristics of relaxation time for heat flux. Some numerical local similarity solutions of the associated problem are computed by two approaches namely (i) the shooting method and (ii) the Keller-box method. The solution is dependent on some interesting parameters which include the viscoelastic fluid parameter β, the dimensionless thermal relaxation time γ and the Prandtl number Pr. Our simulations indicate that variation in the temperature distribution with an increase in local Deborah number γ is non-monotonic. The results for the Fourier’s heat conduction law can be obtained as special cases of the present study.
Soil compaction and controlled traffic considerations in Australian cotton-farming systems
Authors: Antille Diogenes L. , Bennett John McL. , Jensen Troy A.
Published: January 2016

A literature review was conducted to collate best practice techniques for soil compaction management within cotton-farming systems in Australia. Universally negative effects of traffic-induced soil compaction on the whole-farm system and the wider environment include: (i) increased gap between attainable and potential yields, (ii) increased costs of energy and labour, (iii) reduced fertiliser-use efficiency, (iv) reduced water use efficiency (irrigation and rainfall), (v) increased tillage intensity. Knowledge gaps that merit research priority, and research strategies, are suggested. These include: (i) identifying wider impacts on farm economics to guide decision-making and development of decision support systems that capture the effects of compaction on fertiliser, water, and energy use efficiency; (ii) predicting risks at the field or subfield scale and implementing precision management of traffic compaction; (iii) canopy management at terminal stages of the crop cycle to manipulate soil-moisture deficits before crop harvest, thereby optimising trafficability for harvesting equipment; (iv) the role of controlled traffic farming (CTF) in mitigating greenhouse gas emissions and loss of soil organic carbon, and in enhancing fertiliser and water-use efficiencies; (v) recent developments in tyre technology, such as low ground-pressure tyres, require investigation to assess their cost-effectiveness compared with other available options; and (vi) catchment-scale modelling incorporating changes in arable land-use, such as increased area under CTF coupled with no- or minimum-tillage, and variable rate technology is suggested. Such modelling should assess the potential of CTF and allied technologies to reduce sediment and nutrient losses, and improve water quality in intensively managed arable catchments. Resources must be efficiently managed within increasingly sophisticated farming systems to enable long-term economic viability of cotton production. Agronomic and environmental performance of cotton farming systems could be improved with a few changes, and possibly, at a reasonable cost. Key to managing soil compaction appears to be encouraging increased adoption of CTF. This process may benefit from financial support to growers, such as agri-environmental stewardships, and it would be assisted by product customisation from machinery manufacturers.
Chlorophyll fluorescence parameters allow the rapid detection and differentiation of plant responses in three different wheat pathosystems
Authors: Ajigboye Olubukola O. , Bousquet Louise , Murchie Erik H. , Ray Rumiana V.
Published: January 2016

The present study was undertaken to identify chlorophyll fluorescence (CF) parameters that can quantify changes in PSII associated with plant responses in three different wheat pathosystems of foliar, stem-base and ear diseases. The pathosystems included powdery mildew caused by Blumeria graminis, eyespot caused by Oculimacula yallundae or Oculimacula acuformis and Fusarium head blight (FHB) caused by Fusarium culmorum, F. avenaceum or F. langsethiae. Fast CF transients (OJIP) were analysed with the JIP-test to determine changes in PSII photochemistry. Measurements on asymptomatic leaves showed that electron transport related parameters (ETo/RC, ψo and ϕEo) were important to identify varietal differences in resistance to powdery mildew during early stages of infection. The same parameters also allowed differentiation between F. langsethiae and other Fusarium spp. Where infections were caused by the necrotrophic pathogens, Oculimacula spp., F. culmorum or F. avenaceum, changes related to maximum efficiency of PSII photochemistry (Fvʹ/Fmʹ) as well as flux of dissipated (DIo/RC), trapped (TRo/RC), or absorbed (ABS/RC) energy per active reaction centers were significant in detecting biotic stress and the effectiveness of fungicide treatment for disease control. Our results demonstrated that Fvʹ/Fmʹ correlated significantly with visual disease and pathogen DNA of different wheat pathosystems. OJIP was shown as a sensitive technique that can be explored as diagnostic tool in future crop disease management and varietal breeding programs.
Digital mapping of pre-European soil carbon stocks and decline since clearing over New South Wales, Australia
Authors: Gray Jonathan M. , Bishop Thomas F. A. , Smith Peter L.
Published: January 2016

Digital soil models and maps have been developed for pre-European (pre-clearing) levels of soil organic carbon (SOC) over New South Wales, Australia. These provide a useful first estimate of natural, unaltered soil conditions before agricultural development, which are potentially important for many carbon-accounting schemes such as those prescribed by the Intergovernmental Panel on Climate Change, carbon-turnover models such as RothC, and soil-condition monitoring programs. The modelling approach adopted included multiple linear regression and Cubist piecewise linear decision trees. It used 1690 soil profiles from undisturbed or only lightly disturbed native vegetation sites across all of eastern Australia, together with a range of covariates representing key soil-forming factors. The digital soil maps of pre-clearing SOC (% and mass) over New South Wales provide a more sophisticated alternative to currently available, equivalent maps. Independent validation of the SOC mass predictions over the top 30 cm revealed a concordance correlation coefficient of 0.76, which was 13% higher than the currently used map. Total pre-clearing SOC stocks amount to 4.21 Gt in the top 30 cm, which compared with a current stock estimate of 3.68 Gt, suggesting a total SOC loss of ~0.53 Gt over the entire state. The extent of SOC decline in both absolute and relative terms was found to be highly dependent on the climate, parent material and land use regime, reaching a maximum decline of 44.3 t/ha or 50.0% relative loss in cooler (moist) conditions over mafic parent materials under regular cropping use. The models also provide valuable pedological insights into the factors controlling SOC levels under natural conditions.
Directional memory arises from long-lived cytoskeletal asymmetries in polarized chemotactic cells
Authors: Prentice-Mott Harrison V. , Meroz Yasmine , Carlson Andreas , Levine Michael A. , Davidson Michael W. , Irimia Daniel , Charras Guillaume T. , Mahadevan L. , Shah Jagesh V.
Published: January 2016

Significance

Cells orient their motility along chemical gradients using sensitive measurements of the external environment, a process termed chemotaxis. How cells sense, respond to, and remember varying environmental stimuli is only just beginning to be understood. Here, we identify a directional memory in chemotactic neutrophil-like cells. This memory allows cells to orient in low signal gradients and even uniform environments. This memory can be modeled by distinct time scales of chemical sensing and cytoskeletal dynamics, pointing to a general strategy of separating time scales for robust behavioral dynamics in cellular systems. Disrupting specific long-lived molecular assemblies erases directional memory. These studies reveal a novel directional memory resulting from distinct molecular time scales and contributing to chemotactic robustness in migrating cells.