bluuebunny/crossref_metadata_2025 huggingface dataset:
Polypyrrole confined in dendrimer-like silica nanoparticles for combined photothermal and chemotherapy of cancer
Authors: Chen Ruokun , Yang Fengdong , Xue Yake , Wei Xinting , Song Laijun , Liu Xianzhi
Published: April 2016

A multifunctional drug delivery system with polypyrrole confined in dendrimer-like silica nanoparticles and DOX loading for chemo-photothermal synergistic therapy of cancer.
Selective hydrogenation of CO2gas to formic acid over nanostructured Ru-TiO2catalysts
Authors: Upadhyay Praveenkumar Ramprakash , Srivastava Vivek
Published: April 2016

Ionic-liquid-mediated TiO2supported Ru for the selective CO2hydrogenation reaction and isolation of HCOOH.
Soft amphiphilic polyesters obtained from PEGs and silicon fatty compounds: structural characterizations and self-assembly studies
Authors: Andrade Daniela , Moya Claudio , Olate Felipe , Gatica Nicolás , Sanchez Susana , Díaz Enzo , Elgueta Elizabeth , Parra María , Dahrouch Mohamed
Published: April 2016

Transesterification polymerizations between a silicon fatty ester derived from methyl 10-undecenoate and polyethylene glycol (PEG) monomers generate amphiphilic biopolyesters ​showing abilities to form micelle and fiber structures.
Preparation and photocatalytic activity of WO3–MWCNT nanocomposite for degradation of naphthalene under visible light irradiation
Authors: Farhadian Mousa , Sangpour Parvaneh , Hosseinzadeh Ghader
Published: April 2016

Preparation and application of the novel and high performance WO3–MWCNT photocatalyst for photodegradation of naphthalene under visible light irradiation.
Molecular logic gates based on DNA tweezers responsive to multiplex restriction endonucleases
Authors: Li Xiao-Yu , Huang Juan , Jiang Hong-Xin , Du Yi-Chen , Han Gui-Mei , Kong De-Ming
Published: April 2016

Self-assembled DNA tweezers containing four different restriction endonuclease recognition sites were designed and a set of logic gates were constructed.
Self-healing of abrasion damage on epoxy resin controlled by ionic liquid
Authors: Saurín N. , Sanes J. , Carrión F. J. , Bermúdez M. D.
Published: April 2016

A conventional epoxy resin thermoset has been modified with ionic liquid concentrations from 7 to 12 wt% to obtain softer, more ductile materials with self-healing ability for surface abrasion damage.
Synthesis and photocatalytic activity of g-C3N4/BiOI/BiOBr ternary composites
Authors: Yuan Ding , Huang Liying , Li Yeping , Xu Yuanguo , Xu Hui , Huang Shuquan , Yan Jia , He Minqiang , Li Huaming
Published: April 2016

A novel ternary composite photocatalyst (g-C3N4/BiOI/BiOBr) was prepared via a facile solvothermal method.
Graphene oxide based coatings on nitinol for biomedical implant applications: effectively promote mammalian cell growth but kill bacteria
Authors: Zhao Changhong , Pandit Santosh , Fu Yifeng , Mijakovic Ivan , Jesorka Aldo , Liu Johan
Published: April 2016

Graphene oxide based coating significantly enhances the proliferation of osteoblastic cells and shows toxicity towards the bacterial cells.
Role of interfacial interactions to control the extent of wrapping of polymer chains on multi-walled carbon nanotubes
Authors: Parija Suchitra , Bhattacharyya Arup R.
Published: April 2016

Transmission electron microscopic image of separated MWCNTs (N51L15G5) showing the wrapped polymer chains on the MWCNTs surface, which corresponds to the α-phase of the PP.
Crystallization of poly(ε-caprolactone) in its immiscible blend with polylactide: insight into the role of annealing histories
Authors: Lv Qiaolian , Wu Defeng , Xie Hui , Peng Sheng , Chen Yang , Xu Chunjiang
Published: April 2016

Cold crystallization of PLA can improve its affinity to PCL in their blends, and crystallized PLA domains have better nucleation effect to PCL crystallization relative to amorphous PLA ones.
A facile approach to silica-modified polysulfone microfiltration membranes for oil-in-water emulsion separation
Authors: Gao Qiao-Ling , Fang Fei , Chen Chen , Zhu Xue-Yan , Li Jing , Tang Hong-Ying , Zhang Zhong-Biao , Huang Xiao-Jun
Published: April 2016

A facile strategy to prepare silica-modified membranes with superhydrophilicity and underwater superoleophobicity was developed. These hybrid membranes can be applied in oil/water separation with high filtration efficiency and pressure endurance.
Understanding ionic bonding – a scan across the Croatian education system
Authors: Vladušić R. , Bucat R. B. , Ožić M.
Published: April 2016

A study was conducted on the understandings of the accepted model of ionic substances that are held by participants at all levels of the chemical education system in Croatia, including secondary school students, university students, and chemistry teachers. We follow the research of Taber who found that a diagram of a layer of a sodium chloride crystal can be perceived by students as due to electrostatic attractions, consistent with the currently accepted view, or in an alternative molecular framework in which ionic bonding is seen as the process of electron transfer from one atom to another. A Croatian translation of the instrument used by Taber was administered to 650 secondary school students, 264 tertiary undergraduate students, and 86 teachers of chemistry at the secondary level. It was found that significant percentages of the participants, including teachers, interpreted the diagram with conceptions consistent with the molecular framework. Significant numbers of participants at all levels showed evidence of beliefs consistent with Taber's categories of a history conjecture (ionic bonds exist only between the partners in electron transfer), a valency conjecture (the number of ionic bonds that an ion can form is dependent on the electron configuration of the parent atom and is related to the number of electrons gained or removed to form a “stable octet”), and a “just forces” conjecture (ionic bonds involve something more than forces of attraction). The existence of alternative conceptions of ionic bonding at all levels of the education system, including among the teachers, is a situation of considerable concern. Obviously the pedagogical content knowledge of teachers cannot be based on an inadequate level of content knowledge. Remedial action seems to be important. As a first step, we speculate on the possible sources of the alternative conceptions. This includes an analysis of the chemical validity of the subject matter that is commonly presented in textbooks.
Flavoenzyme CrmK-mediated substrate recycling in caerulomycin biosynthesis
Authors: Zhu Yiguang , Picard Marie-Ève , Zhang Qingbo , Barma Julie , Després Xavier Murphy , Mei Xiangui , Zhang Liping , Duvignaud Jean-Baptiste , Couture Manon , Zhu Weiming , Shi Rong , Zhang Changsheng
Published: April 2016

Biochemical and structural investigations into the flavoenzyme CrmK reveal a substrate recycling/salvaging mechanism in caerulomycin biosynthesis.
Ruthenium decorated hierarchically ordered macro–mesoporous carbon for lithium oxygen batteries
Authors: Guo Xin , Sun Bing , Zhang Jinqiang , Liu Hao , Wang Guoxiu
Published: April 2016

A ruthenium-decorated hierarchically ordered macro–mesoporous carbon (MmC@Ru) obtainedviaa mixed template method exhibits excellent electrochemical performance for lithium oxygen batteries.
Synthesis and characterization of robust, mesoporous electrodes for solid oxide fuel cells
Authors: Almar Laura , Morata Alex , Torrell Marc , Gong Mingyang , Liu Meilin , Andreu Teresa , Tarancón Albert
Published: April 2016

The use of mesoporous electrodes in solid oxide cells would lead to a significant enhancement of the performance due to their high surface area and large number of active sites for electrochemical reactions.
A self-standing nanoporous MoP2 nanosheet array: an advanced pH-universal catalytic electrode for the hydrogen evolution reaction
Authors: Zhu Wenxin , Tang Chun , Liu Danni , Wang Jianlong , Asiri Abdullah M. , Sun Xuping
Published: April 2016

A self-standing MoP2 nanosheet array on carbon cloth acts as a robust pH-universal catalytic electrode for the hydrogen evolution reaction with high activity.
Reduced leakage current and improved performance of an organic photodetector using an ytterbium cathode interlayer
Authors: Lim Seong Bin , Ji Chan Hyuk , Oh Il Soo , Oh Se Young
Published: April 2016

The main contribution of this paper is a demonstration of the electron transport and hole-blocking properties of ytterbium, which make it outstanding for use as the cathode interlayer in organic photodetectors.
Giant nonlinear optical responses of carbyne
Authors: Ma C. R. , Xiao J. , Yang G. W.
Published: April 2016

Carbyne has been synthesized in the laboratory and the giant nonlinear optical responses of carbyne have been demonstrated.
A perylene bisimide derivative with a LUMO level of −4.56 eV for non-fullerene solar cells
Authors: Yu Yaping , Yang Fan , Ji Yunjing , Wu Yonggang , Zhang Andong , Li Cheng , Li Weiwei
Published: April 2016

Conjugated polymers with LUMO levels of −4.00 eV combined with a newly designed perylene bisimide compound with a LUMO level of −4.56 eV were found to have efficient charge transfer and provide power conversion efficiencies up to 1.4% in solar cells.
Spironolactone promotes autophagy via inhibiting PI3K/AKT/mTOR signalling pathway and reduce adhesive capacity damage in podocytes under mechanical stress
Authors: Li Dong , Lu Zhenyu , Xu Zhongwei , Ji Junya , Zheng Zhenfeng , Lin Shan , Yan Tiekun
Published: April 2016

Mechanical stress which would cause deleterious adhesive effects on podocytes is considered a major contributor to the early progress of diabetic nephropathy (DN). Our previous study has shown that spironolactone could ameliorate podocytic adhesive capacity in diabetic rats. Autophagy has been reported to have a protective role against renal injury. The present study investigated the underlying mechanisms by which spironolactone reduced adhesive capacity damage in podocytes under mechanical stress, focusing on the involvement of autophagy. Human conditional immortalized podocytes exposed to mechanical stress were treated with spironolactone, LY294002 or rapamycin for 48 h. The accumulation of LC3 puncta was detected by immunofluorescence staining. Podocyte expression of mineralocorticoid receptor (MR), integrin β1, LC3, Atg5, p85-PI3K, p-Akt, p-mTOR were detected by Western blotting. Podocyte adhesion to collagen type IV was also performed with spectrophotometry. Immunofluorescence staining showed that the normal level of autophagy was reduced in podocytes under mechanical stress. Decreased integrin β1, LC3, Atg5 and abnormal activation of the PI3K/Akt/mTOR pathway were also detected in podocytes under mechanical stress. Spironolactone up-regulated integrin β1, LC3, Atg5 expression, down-regulated p85-PI3K, p-Akt, p-mTOR expression and reduced podocytic adhesive capacity damage. Our data demonstrated that spironolactone inhibited mechanical-stress-induced podocytic adhesive capacity damage through blocking PI3K/Akt/mTOR pathway and restoring autophagy activity.
The complexity of signalling mediated by the glucagon-like peptide-1 receptor
Authors: Fletcher Madeleine M. , Halls Michelle L. , Christopoulos Arthur , Sexton Patrick M. , Wootten Denise
Published: April 2016

The glucagon-like peptide-1 receptor (GLP-1R) is a class B GPCR that is a major therapeutic target for the treatment of type 2 diabetes. The receptor is activated by the incretin peptide GLP-1 promoting a broad range of physiological effects including glucose-dependent insulin secretion and biosynthesis, improved insulin sensitivity of peripheral tissues, preservation of β-cell mass and weight loss, all of which are beneficial in the treatment of type 2 diabetes. Despite this, existing knowledge surrounding the underlying signalling mechanisms responsible for the physiological actions downstream of GLP-1R activation is limited. Here, we review the current understanding around GLP-1R-mediated signalling, in particular highlighting recent contributions to the field on biased agonism, the spatial and temporal aspects for the control of signalling and how these concepts may influence future drug development.
The Drosophila photoreceptor as a model system for studying signalling at membrane contact sites
Authors: Yadav Shweta , Cockcroft Shamshad , Raghu Padinjat
Published: April 2016

Several recent studies have demonstrated the existence of membrane contact sites (MCS) between intracellular organelles in eukaryotic cells. Recent exciting studies have also demonstrated the existence of biomolecular interactions at these contact sites in mediating changes in the membrane composition of the cellular compartments. However, the role of such contact sites in regulating organelle function and physiological processes remains less clear. In this review we discuss the existence of a contact site between the plasma membrane (PM) and the endoplasmic reticulum (ER) in Drosophila photoreceptors. Further, we discuss the role of specific proteins present at this location in regulating phospholipid turnover and its impact in regulating a physiological process, namely phototransduction.
Structural comparison of yeast and human intra-mitochondrial lipid transport systems
Authors: Miliara Xeni , Matthews Stephen
Published: April 2016

Mitochondria depend on a tightly regulated supply of phospholipids. The protein of relevant evolutionary and lymphoid interest (PRELI)/Ups1 family together with its mitochondrial chaperones [TP53-regulated inhibitor of apoptosis 1 (TRIAP1)/Mdm35] represents a unique heterodimeric lipid-transfer system that is evolutionary conserved from yeast to man. Recent X-ray crystal structures of the human and yeast systems are compared and discuss here and shed new insight into the mechanism of the PRELI/Ups1 system.
Lipid transfer proteins do their thing anchored at membrane contact sites… but what is their thing?
Authors: Wong Louise H. , Levine Tim P.
Published: April 2016

Membrane contact sites are structures where two organelles come close together to regulate flow of material and information between them. One type of inter-organelle communication is lipid exchange, which must occur for membrane maintenance and in response to environmental and cellular stimuli. Soluble lipid transfer proteins have been extensively studied, but additional families of transfer proteins have been identified that are anchored into membranes by transmembrane helices so that they cannot diffuse through the cytosol to deliver lipids. If such proteins target membrane contact sites they may be major players in lipid metabolism. The eukaryotic family of so-called Lipid transfer proteins Anchored at Membrane contact sites (LAMs) all contain both a sterol-specific lipid transfer domain in the StARkin superfamily (related to StART/Bet_v1), and one or more transmembrane helices anchoring them in the endoplasmic reticulum (ER), making them interesting subjects for study in relation to sterol metabolism. They target a variety of membrane contact sites, including newly described contacts between organelles that were already known to make contact by other means. Lam1–4p target punctate ER–plasma membrane contacts. Lam5p and Lam6p target multiple contacts including a new category: vacuolar non-NVJ cytoplasmic ER (VancE) contacts. These developments confirm previous observations on tubular lipid-binding proteins (TULIPs) that established the importance of membrane anchored proteins for lipid traffic. However, the question remaining to be solved is the most difficult of all: are LAMs transporters, or alternately are they regulators that affect traffic more indirectly?
Development of chimeric antigen receptors for multiple myeloma
Authors: Martínez-Cingolani Carolina , Bories Jean Christophe
Published: April 2016

Multiple myeloma (MM) is a haematologic malignancy characterized by the expansion of monoclonal plasma cells in the bone marrow. It is associated with serum or urine monoclonal protein and organ damage including renal failure, anaemia, hypercalcaemia and bone lesions. Despite recent improvements MM still remains an incurable disease. Previous studies have shown that the adoptive transfer of autologous T-cells modified to express chimeric antigen receptors (CAR) is effective in cases of acute and chronic lymphoid leukaemia. However, the adjustment of CAR-T-cell therapy to MM is hindered by the scarcity of antigens specific to the tumour plasma cells. Most candidate targets are shared by healthy tissues, and entail high risks of toxicity. Therefore several strategies have been proposed to regulate CAR-T-cell function as well as to enhance CAR-T-cell specificity against tumour cells. In this article we summarize the surface markers that have been investigated as targets to eliminate MM plasma cells and the MM-specific CARs that have been developed to date. Then we describe the different CAR-T-cell designs that could be applied in the case of MM to circumvent current problems of toxicity.
Structure network analysis to gain insights into GPCR function
Authors: Fanelli Francesca , Felline Angelo , Raimondi Francesco , Seeber Michele
Published: April 2016

G protein coupled receptors (GPCRs) are allosteric proteins whose functioning fundamentals are the communication between the two poles of the helix bundle. Protein structure network (PSN) analysis is one of the graph theory-based approaches currently used to investigate the structural communication in biomolecular systems. Information on system's dynamics can be provided by atomistic molecular dynamics (MD) simulations or coarse grained elastic network models paired with normal mode analysis (ENM–NMA). The present review article describes the application of PSN analysis to uncover the structural communication in G protein coupled receptors (GPCRs). Strategies to highlight changes in structural communication upon misfolding, dimerization and activation are described. Focus is put on the ENM–NMA-based strategy applied to the crystallographic structures of rhodopsin in its inactive (dark) and signalling active (meta II (MII)) states, highlighting changes in structure network and centrality of the retinal chromophore in differentiating the inactive and active states of the receptor.
Bistatic MIMO radar for near field source localisation using PARAFAC
Authors: Singh P.R. , Wang Y. , Chargé P.
Published: April 2016

A near field targets localisation method using parallel factor (PARAFAC) decomposition with a bistatic MIMO system is presented. PARAFAC has the interesting properties of uniqueness in the decomposition of tensor constructed from the received signal and automatic pairing of emitter and receiver directional vectors of a bistatic MIMO radar, which allow the estimation of the parameters of each source individually. Furthermore, the proposed method provides very good estimation performance, because it does not require the approximation of the directional vectors contrary to the most existing techniques.
On new efficient μ‐law‐based method for feedback compensation in hearing aids
Authors: Vasundhara  , Panda G. , Puhan N.B.
Published: April 2016

The affine‐projection‐like (APL) algorithm is reported to achieve lower computations than affine‐projection algorithm (APA) without compromising the steady‐state performance. Further, the performance accuracy of the adaptive feedback canceller (AFC) in hearing aids is enhanced using an improved proportionate APL (IPAPL) algorithm. Two new learning algorithms are proposed for AFC, which apply the memory of previous gain factors and μ‐law proportionate technique to the IPAPL, termed as memorised IPAPL (MIPAPL) and μ‐law MIPAPL (MMIPAPL), respectively. In addition, a segmented approach is also suggested which offers computational advantage over MMIPAPL. The results obtained from simulation‐based experiments demonstrate that the proposed methods achieve faster convergence rate than the existing methods.
Nonlinear MNL‐FDTD scheme for short‐gap electrostatic discharge simulation
Authors: Fujita K.
Published: April 2016

A nonlinear and partially implicit finite‐difference time‐domain scheme with a relaxed stability condition is presented for fast full‐wave simulation of electrostatic discharges occurred at a short gap. The nonlinear spark resistance model of Rompe and Weizel is directly incorporated in this scheme. Its stability, accuracy and computational efficiency are assessed in the application to a metallic structure system.
Selection relaying in decode‐and‐forward multi‐hop cognitive radio systems using energy detection
Authors: Goel Dhanesh , Sai Krishna Vemuri , Bhatnagar Manav
Published: April 2016

In this study, the authors have analysed the performance of selection relaying at each hop in a decode‐and‐forward (DF)‐based multi‐hop cognitive radio (CR) system deploying cooperative spectrum sensing. The decisions on spectrum availability are taken by a number of sensing CRs (SCRs) at the first level and are sent to a fusion centre (FC) over pre‐existing clusters of relaying CRs (RCRs). The RCRs are being used in a secondary role for relaying the spectrum decision besides sensing their own area primary user. The decision of each SCR is relayed to FC one‐by‐one via number of RCR clusters by selecting a maximum signal‐to‐noise ratio link at each cluster independently. The selected RCR forwards the decision to the next level using DF protocol. The closed‐form expressions for probability of missed detection and false alarm are derived at the FC. An optimal combining rule is devised at the FC. A comparative graphical analysis of power saving in case of multi‐hop transmission to that of single‐hop transmission is also presented. The number of hops for the considered system is optimised based on a trade‐off relation between error rate and transmission delay.
Theoretical and experimental analyses of a hybrid excitation synchronous generator with integrated brushless excitation
Authors: Zhu Shushu , Liu Chuang , Wang Kai , Hu Yaohua , Ning Yinhang
Published: April 2016

This paper proposes a novel integrated brushless excitation method (IBEM) for a rotor‐excited generator. IBEM is applied to a rotor‐excited hybrid excitation synchronous generator (HESG) to realise brushless excitation while the key features of the rotor‐excited generator are maintained. The new generator is referred as IBE HESG here. The stator excitation windings are buried in the stator slots. The static excitation field is established in the air gap when there is dc excitation current in the stator excitation windings. The three‐phase armature coils of the rotor induce the static excitation field and provide the dc excitation current for the rotor excitation windings via a rotating rectifier. The operating principles are discussed theoretically. The magnetic field distribution and the operating characteristics are studied by finite‐element analysis. The no‐load, external, regulation and excitation characteristics are analysed. Compared with the brush excitation HESG, the rotor excitation current is able to meet the requirement and the output voltage is conveniently regulated by the stator excitation current. Finally, a 1.5 kVA prototype is fabricated to test the operating characteristics of IBE HESG. It demonstrates that the brushless excitation is realised and the output voltage is regulated by the stator excitation current.
Integrated radial/thrust magnetic bearing without thrust disk for a high‐speed driving system
Authors: Han Bangcheng , Xu Qinjie , Zheng Shiqiang
Published: April 2016

In this paper, the authors present a novel compact structure of an integrated radial/thrust magnetic bearing (IRTMB) without thrust disk. The structure without thrust disk can further reduce the frictional and windage loss for a high‐speed driving system. At the same time the rotor supported by the two IRTMBs can further reduce its axial size, and improve rotor dynamic performance. The axially magnetised magnet forms a cylindrical magnet sandwiched between a four‐leg laminated radial stator and a solid return pole piece. On the basis of the return pole, a novel air gap, called the return air gap, is constructed between the rotor and the return pole. The bias flux produced by the permanent magnet and the control flux produced by the thrust magnetic bearing (TMB) unit are conducted by this return pole. The magnet produces the bias flux for radial and TMB units, and separates the control flux loops of radial and TMB units. The IRTMB structure and its analytical models are deduced using equivalent magnetic circuit method. To study the performances of the IRTMB, another IRTMB with thrust disk used in a high‐speed motor with power of 45 kW at 60,000 rev/min has been fabricated and is chosen as the comparison target.
Integration of the hysteresis in models of asymmetric three‐phase transformer: finite‐element and dynamic electromagnetic models
Authors: Aboura Faouzi , Touhami Omar
Published: April 2016

This paper deals with the models elaboration for the asymmetric three‐phase transformers. The first model uses the principle of the hysteresis integration in two‐dimensional finite‐element method (FEM) with magnetic field calculations. This method is based on inverse Jiles–Atherton hysteresis model. The second one is a dynamic electromagnetic model (DEM) based on Tellinen hysteresis model. The DEM and FEM models used in ferromagnetic cores have been modified by replacing the anhysteretic curve by the hysteresis loop. A simulation in time domain is carried out and the simulated results are compared with those obtained experimentally to validate the proposed approach. An error calculation is performed to show the accuracy of results obtained by DEM and FEM models.
Simplified model predictive direct torque control method without weighting factors for permanent magnet synchronous generator‐based wind power system
Authors: Guo Leilei , Zhang Xing , Yang Shuying , Xie Zhen , Wang Lingxiang , Cao Renxian
Published: April 2016

Conventional model predictive direct torque control (MP‐DTC) of permanent magnet synchronous generator (PMSG) suffers from weighing factor tuning work and relatively large calculation amount. This study proposes a simplified MP‐DTC method without weighting factors for PMSG‐based wind power system. First, the torque and stator flux magnitude are predicted on the stationary reference frame instead of on the synchronous rotating reference frame, hence reducing the calculation amount. Second, a new cost function based on the torque and the reactive torque is developed in this study. As the torque and the reactive torque have the same order of magnitude, the weighting factor which is needed in the conventional MP‐DTC system is eliminated. Meanwhile, the stator current and stator flux magnitude can be controlled indirectly by controlling the torque and reactive torque simultaneously, which ensures the stability of the system. Besides, the robustness of the proposed strategy to unknown PMSG parameter variations is improved to a certain extent. The experimental results validate the effectiveness of the proposed method.
Research on characteristics of first‐order sea clutter for high‐frequency sky–surface wave radar
Authors: Ya‐jun Li , Shu‐wen Wang , Sheng Shao , Zhuo‐qun Wang , Yin‐sheng Wei , Rong‐qing Xu
Published: April 2016

In high‐frequency (HF) hybrid sky–surface wave radar, the first‐order sea clutter broadening is severe under the influence of the ionosphere and bistatic angle. This affects the detection of ship targets. Thereby a comprehensive analysis is essential and will be presented in this study. First, according to the geometry configuration and detection characteristics of this new system radar, the positioning principle and the range of grazing angle are analysed. Then, the first‐order sea clutter Bragg frequency is presented and broadening model is given on the basis of the system configuration. Next, the mechanism of first‐order sea clutter frequency shift and broadening is explained and, based on the system layout, simulation is provided to illustrate the effects of various factors on first‐order sea clutter, including ionosphere, grazing angle and bistatic angle. Moreover, the characteristics of sea clutter frequency shift and broadening in different range and azimuth are analysed. Finally, the results of theoretical analysis are compared with the experimental data based on the newly‐developed integrated experimental system, and the dominant factor of sea clutter broadening is studied. Simulation results show that the results of experiment are consistent with that of theoretical analysis.
Ripple‐reduced model predictive direct power control for active front‐end power converters with extended switching vectors and time‐optimised control
Authors: Fang Hui , Zhang Zhenbin , Feng Xiaoyun , Kennel Ralph
Published: April 2016

Model predictive control (MPC) is an attractive technique for power electronics and drives. It requires no extra modulators and considers the non‐linear nature of the power converter, so remarkable control performance can be achieved. However, since the conventional MPC scheme uses only one switching state during the whole control interval, ripples of the control variables are more evident than that of the classical modulator based techniques. This study proposed a ripple‐reduced model predictive direct power control (RR‐MPDPC) scheme for the grid‐tied active front end using a fully field programmable gate array‐based platform. The novelty of the proposed RR‐MPDPC is that through extended switching vectors and time‐optimised control, more freedoms and precise tracking possibility are realised in the predictive controller. The proposed control scheme is compared with the conventional MPDPC and the recently reported duty optimal MPDPC scheme (DutyOpt‐MPDPC) through experimental data. Experimental results confirm that better performance is achieved using the proposed RR‐MPDPC scheme.
Design and application of the digital multifunctional ionosonde
Authors: Gong Wanlin , Cui Xiao , Pan Lingyun
Published: April 2016

A multifunctional ionosonde was designed for ionospheric scientific research and monitoring applications by the Ionospheric Laboratory of Wuhan University during 2012–2014. This ionosonde is a high‐frequency (HF) radar using inter‐pulse phase codes and linear frequency modulation with high sensitivity. The two basic sounding modes of the radio system are the fixed frequency mode and the swept frequency mode. Both the radar waveform and the sounding mode are optional, based on practical considerations. This ionosonde can be applied to study the space environment, for applications such as to observe the disturbance and irregularities in the ionospheric E‐ and F‐layers, to record the propagation features of the HF radio waves, to detect the state of the ocean and so on. With different transmitting antennae, the same ionosonde can operate as a vertical‐incidence ionosonde, an oblique‐incidence ionosonde or an oblique‐backscatter ionosonde. Specifically, the ionosonde could be used to detect the state of the ocean by combining the sky wave with the ground wave. In this study, the architecture of the multifunctional ionosonde is introduced, and some initial observations of this ionosonde are presented.
Hybrid wireless sensor networks: a reliability, cost and energy‐aware approach
Authors: Zonouz Amir Ehsani , Xing Liudong , Vokkarane Vinod M. , Sun Yan (Lindsay)
Published: April 2016

Wireless sensor networks (WSNs) consist of spatially distributed sensor nodes to monitor physical or environmental conditions. These sensor nodes are typically battery‐powered sensor nodes (BPSNs) and can rarely meet design goals of long network lifetime and high reliability. Energy‐harvesting sensor nodes (EHSNs) that convert different types of energy to electrical energy are an alternative type of sensor nodes with a long lifetime but a high cost. Combining BPSNs and EHSNs has potential to deal with the conflicting design goals of long lifetime and reasonably low cost. In this study, the authors make new contributions by modelling a heterogeneous WSN consisting of both BPSNs and EHSNs and proposing a comprehensive cost function‐based routing approach that integrates end‐to‐end path reliability, cost and energy consumption for providing satisfactory quality of service to applications running on hybrid WSNs. Another contribution made in this work is the optimal deployment of EHSNs using a reliability‐importance‐analysis‐based method to improve the end‐to‐end path reliability within hybrid WSNs.
NEECP: Novel energy‐efficient clustering protocol for prolonging lifetime of WSNs
Authors: Singh Samayveer , Chand Satish , Kumar Rajeev , Malik Aruna , Kumar Bijendra
Published: April 2016

In this paper, a novel energy‐efficient clustering protocol (NEECP) for increasing the network lifetime in wireless sensor networks is proposed. This technique selects the cluster heads in an effective way with an adjustable sensing range and performs data aggregation using chaining approach. It also avoids transmission of redundant data by using a redundancy check function for improving the network lifetime. It is implemented by considering the data with aggregation and without aggregation. The NEECP without aggregation increases the network lifetime by 59.76 and 7.17% as compared with the hybrid energy‐efficient distributed (HEED) and intra‐balanced low‐energy adaptive clustering hierarchy (IBLEACH), respectively. It increases the network lifetime by 122.92 and 49.53% over the HEED and IBLEACH, respectively, while considering data aggregation.
Surface properties that can be displayed by a microelectromechanical system‐based mechanical tactile display
Authors: Kosemura Yumi , Hasegawa Shoichi , Miki Norihisa
Published: April 2016

This study reports the surface properties that a microelectromechanical system (MEMS)‐based mechanical tacitle display can present. The display is composed of 3 by 3 large displacement MEMS actuators that comprise hydraulic displacement amplification mechanism and piezoelectric actuators. The control parameters of the display include the displacement, or driving voltage, vibration frequency, and spatial and temporal actuation patterns of the actuators. Roughness and hardness using the newly proposed sample comparison method have been investigated previously. In this study, methods investigating warmness, or thermal conductivity, wettability, or surface energy, and friction were considered. Correlation between the control parameters and the surface properties indicated that the mechanical tactile display is best at controlling the roughness of the surface.
Study of nitric oxide degradation properties of photoactive concrete containing nitrogen and/or carbon co‐modified titanium dioxide – preliminary findings
Authors: Janus Magdalena , Zatorska Justyna , Zając Kamila , Kusiak‐Nejman Ewelina , Czyżewski Adam , Morawski Antoni Waldemar
Published: April 2016

In recent years, titanium dioxide (TiO2) has been commonly applied in the production of photoactive concrete materials capable of degrading a wide range of air contaminant such as nitric oxide (NO), VOC etc. It was confirmed that the photocatalytic activity of TiO2 can be further enhanced by modifying the photocatalyst with non‐metals such as nitrogen (N) or carbon (C). In view of this finding, several concrete/TiO2 composites consisting of commercial concrete and raw anatase TiO2 (supplied by Grupa Azoty Zakłady Chemiczne ‘POLICE’ S.A., Poland), previously modified with ammonia [N source] and/or 2‐propanol [C source] have been manufactured. For reference, the additional concrete samples were prepared, containing unmodified TiO2 and commercial titania P25 (Evonik). The NO degradation properties of prepared photoactive concrete materials were evaluated using laboratory test set‐up. The measurements were conducted under constant temperature and humidity conditions, using ultraviolet light irradiation. Significant NO removal was recorded for the TiO2/concrete composites containing N and/or C co‐modified titania. The results were related to the improved photocatalytic activity of modified photocatalysts and probable, partial NO reduction to N2, via the selective catalytic reduction process catalysed by TiO2.
Extraction of magnetic nanoparticles using magnetic ionic liquids
Authors: Zhao Yansong , Hansen Jørn H. , Boström Tobias
Published: April 2016

Magnetic nanoparticles display a range of unique properties of interest to fields such as water treatment, drug delivery, catalysis, and many more. Widespread use of magnetic nanoparticles relies heavily on one's ability to separate them effectively from other media, for example in water treatment. In this work, an efficient method to separate magnetic nanoparticles from organic solvent using magnetic ionic liquids is demonstrated for the first time. Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, and microscopy were employed to investigate the authors’ model system. This work will greatly impact future directions in the science of separating nanoparticles and applications of ionic liquids.
Interface and photoluminescence characteristics of graphene-(GaN/InGaN)n multiple quantum wells hybrid structure
Authors: Wang Liancheng , Liu Zhiqiang , Zhang Zi-Hui , Tian Ying Dong , Yi Xiaoyan , Wang Junxi , Li Jinmin , Wang Guohong
Published: April 2016

The effects of graphene on the optical properties of active system, e.g., the InGaN/GaN multiple quantum wells, are thoroughly investigated and clarified. Here, we have investigated the mechanisms accounting for the photoluminescence reduction for the graphene covered GaN/InGaN multiple quantum wells hybrid structure. Compared to the bare multiple quantum wells, the photoluminescence intensity of graphene covered multiple quantum wells showed a 39% decrease after excluding the graphene absorption losses. The responsible mechanisms have been identified with the following factors: (1) the graphene two dimensional hole gas intensifies the polarization field in multiple quantum wells, thus steepening the quantum well band profile and causing hole-electron pairs to further separate; (2) a lower affinity of graphene compared to air leading to a weaker capability to confine the excited hot electrons in multiple quantum wells; and (3) exciton transfer through non-radiative energy transfer process. These factors are theoretically analysed based on advanced physical models of semiconductor devices calculations and experimentally verified by varying structural parameters, such as the indium fraction in multiple quantum wells and the thickness of the last GaN quantum barrier spacer layer.
The effect of oxide shell thickness on the structural, electronic, and optical properties of Si-SiO2 core-shell nano-crystals: A (time dependent)density functional theory study
Authors: Nazemi Sanaz , Pourfath Mahdi , Soleimani Ebrahim Asl , Kosina Hans
Published: April 2016

Due to their tunable properties, silicon nano-crystals (NC) are currently being investigated. Quantum confinement can generally be employed for size-dependent band-gap tuning at dimensions smaller than the Bohr radius (∼5 nm for silicon). At the nano-meter scale, however, increased surface-to-volume ratio makes the surface effects dominant. Specifically, in Si-SiO2 core-shell semiconductor NCs the interfacial transition layer causes peculiar electronic and optical properties, because of the co-existence of intermediate oxidation states of silicon (Sin+, n = 0–4). Due to the presence of the many factors involved, a comprehensive understanding of the optical properties of these NCs has not yet been achieved. In this work, Si-SiO2 NCs with a diameter of 1.1 nm and covered by amorphous oxide shells with thicknesses between 2.5 and 4.75 Å are comprehensively studied, employing density functional theory calculations. It is shown that with increased oxide shell thickness, the low-energy part of the optical transition spectrum of the NC is red shifted and attenuated. Moreover, the absorption coefficient is increased in the high-energy part of the spectrum which corresponds to SiO2 transitions. Structural examinations indicate a larger compressive stress on the central silicon cluster with a thicker oxide shell. Examination of the local density of states reveals the migration of frontier molecular orbitals from the oxide shell into the silicon core with the increase of silica shell thickness. The optical and electrical properties are explained through the analysis of the density of states and the spatial distribution of silicon sub-oxide species.
Development of a scanning time of flight microscope and its application to the study of charge transport in phase separated structured organic semiconductors
Authors: Paul Sanjoy , Ellman Brett , Tripathi Suvagata , Singh Gautam , Twieg Robert J.
Published: April 2016

We describe a tool for studying the two-dimensional spatial variation in electronic properties of organic semiconductors: the scanning time-of-flight microscope (STOFm). The STOFm simultaneously measures the transmittance of polarized light and time-of-flight current transients with a pixel size <30 μm, making it especially valuable for studies of the correlations of structure with charge generation and transport in liquid crystalline organic semiconductors (LC OSCs). Adapting a previously developed photopolymerization technique, we characterize the instrument using patterned samples of a LC OSC bounded by a non-semiconducting polymer matrix.
Equivalences and correspondences between the deforming body induced flow and heat in two-three dimensions
Authors: Turkyilmazoglu Mustafa
Published: April 2016

This paper is concerned with the analysis of magnetohydrodynamic fluid flow and heat transfer due to two-three dimensional porous and deforming (stretching/shrinking) bodies. It is aimed to prove from a theoretical approach that several boundary value problems regardless of two or three dimensions associated with the stretching/shrinking surfaces having different physical origin result in either the equivalent structure of governing equations or the interchangeable role of mechanisms of stretching or shrinking. Therefore, a link is created between the deforming surface phenomena considered in different geometries in the open literature. On the grounds of the provided theorems, a special care must be paid before working on the variations of this physical phenomenon, since the skin friction and the rate of heat transfer of engineering interest may have already been extracted from an already studied twin problem, namely the two-dimensional nonlinear (power-law) deformation analysis. It is further shown that the radial nonlinear stretching/shrinking sheet problem also evolves into the two-dimensional nonlinear wall deformation problem.
Numerical study of particle-induced Rayleigh-Taylor instability: Effects of particle settling and entrainment
Authors: Chou Yi-Ju , Shao Yun-Chuan
Published: April 2016

In this study, we investigate Rayleigh-Taylor instability in which the density stratification is caused by the suspension of particles in liquid flows using the conventional single-phase model and Euler-Lagrange (EL) two-phase model. The single-phase model is valid only when the particles are small and number densities are large, such that the continuum approximation applies. The present single-phase results show that the constant settling of the particle concentration restricts the lateral development of the vortex ring, which results in a decrease of the rising speed of the Rayleigh-Taylor bubbles. The EL model enables the investigation of particle-flow interaction and the influence of particle entrainment, resulting from local non-uniformity in the particle distribution. We compare bubble dynamics in the single-phase and EL cases, and our results show that the deviation between the two cases becomes more pronounced when the particle size increases. The main mechanism responsible for the deviation is particle entrainment, which can only be resolved in the EL model. We provide a theoretical argument for the small-scale local entrainment resulting from the local velocity shear and non-uniformity of the particle concentration. The theoretical argument is supported by numerical evidence. Energy budget analysis is also performed and shows that potential energy is released due to the interphase drag and buoyant effect. The buoyant effect, which results in the transformation of potential energy into kinetic energy and shear dissipation, plays a key role in settling enhancement. We also find that particle entrainment increases the shear dissipation, which in turn enhances the release of potential energy.
Robust Pb2+ sensor based on flexible ZnO/ZnS core-shell nanoarrays
Authors: Zhao Zhenfu , Jiang Chunyan , Pu Xiong , Du Chunhua , Li Linxuan , Ma Bei , Hu Weiguo
Published: April 2016

We designed a flexible robust sensor with ZnO/ZnS core-shell nanoarrays to detect Pb2+ ions. This device is powered by electrical energy transferred from the environmental mechanical energy and senses Pb2+ ions with the cation exchange reaction between ZnS shell and Pb2+ ions (ZnS (s) + Pb2+ (aq) ↔ PbS (s) + Zn2+(aq)). The high density intrinsic carriers in PbS diffuse into the ZnO core to partly screen the piezopotential, which results in an exponential relationship between the concentrations of Pb2+ ions and the piezo-voltages. The detected limit is as low as 1 ppm. This sensor also exhibits a very high selectivity towards Pb2+ ions due to the limitation of energy band and solubility, which has potential applications in environmental protection and pollutant surveillance.
Electronic band structure and optical gain of GaNxBiyAs1−x−y/GaAs pyramidal quantum dots
Authors: Song Zhi-Gang , Bose Sumanta , Fan Wei-Jun , Li Shu-Shen
Published: April 2016

The electronic band structure and optical gain of GaNxBiyAs1−x−y/GaAs pyramidal quantum dots (QDs) are investigated using the 16-band k ⋅ p model with constant strain. The optical gain is calculated taking both homogeneous and inhomogeneous broadenings into consideration. The effective band gap falls as we increase the composition of nitrogen (N) and bismuth (Bi) and with an appropriate choice of composition we can tune the emission wavelength to span within 1.3 μm–1.55 μm, for device application in fiber technology. The extent of this red shift is more profound in QDs compared with bulk material due to quantum confinement. Other factors affecting the emission characteristics include virtual crystal, strain profile, band anticrossing (BAC), and valence band anticrossing (VBAC). The strain profile has a profound impact on the electronic structure, specially the valence band of QDs, which can be determined using the composition distribution of wave functions. All these factors eventually affect the optical gain spectrum. With an increase in QD size, we observe a red shift in the emission energy and emergence of secondary peaks owing to transitions or greater energy compared with the fundamental transition.
Resonant tunneling spectroscopy of valley eigenstates on a donor-quantum dot coupled system
Authors: Kobayashi T. , van der Heijden J. , House M. G. , Hile S. J. , Asshoff P. , Gonzalez-Zalba M. F. , Vinet M. , Simmons M. Y. , Rogge S.
Published: April 2016

We report on electronic transport measurements through a silicon double quantum dot consisting of a donor and a quantum dot. Transport spectra show resonant tunneling peaks involving different valley states, which illustrate the valley splitting in a quantum dot on a Si/SiO2 interface. The detailed gate bias dependence of double dot transport allows a first direct observation of the valley splitting in the quantum dot, which is controllable between 160 and 240 μeV with an electric field dependence 1.2 ± 0.2 meV/(MV/m). A large valley splitting is an essential requirement for implementing a physical electron spin qubit in a silicon quantum dot.