bluuebunny/crossref_metadata_2025 huggingface dataset:
Salivary tissue factor concentration and activity in patients with oral lichen planus
Authors: Tunali‐Akbay Tugba , Solmaz Zeliha , Namdar Pekiner Filiz , İpekci Hazal
Published: December 2016

Purpose: This study aimed to evaluate the tissue factor (TF) concentration and activity in patients with oral lichen planus (OLP) under oxidative stress.

Methods: Twenty patients with OLP were selected from the patients who were referred for treatment to the Marmara University, Faculty of Dentistry, Oral and Maxillofacial Radiology Department. Twenty healthy subjects from faculty staff and their family members were selected for the study. Salivary TF concentration and TF activity; total oxidant capacity; total antioxidant capacity; total thiol, malondialdehyde and glutathione concentrations; and oxidative stress index were measured in saliva samples.

Results: Salivary total oxidant capacity, oxidative stress index and malondialdehyde and TF concentration and activity were significantly increased in the patient group compared to those in the control group. Total thiol and glutathione concentration and total antioxidant capacity were significantly decreased in the patient group.

Conclusion: Impaired oxidant‐antioxidant balance and inflammatory features of OLP might cause an increase in the salivary TF concentration and activity. As TF factor plays a critical role in inflammation progress, the use of an antioxidant agent in OLP may decrease the salivary TF concentration by decreasing oxidative stress. The findings of this study might represent a novel approach to OLP monitoring and treatment in terms of TF as the measurement of TF is easy and cost‐effective.
Do Banks Issue Equity When They Are Poorly Capitalized?
Authors: Dinger Valeriya , Vallascas Francesco
Published: December 2016

Debt overhang and moral hazard predict that poorly capitalized banks have a lower likelihood to issue equity, while the presence of regulatory and market pressures posits an opposite theoretical prediction. By using an international sample of bank seasoned equity offerings (SEOs), we show that the likelihood of issuing SEOs is higher in poorly capitalized banks and that such banks prefer SEOs to alternative capitalization strategies. A series of tests exploring the variation of capital regulation and market discipline show that market mechanisms rather than capital regulation are the primary driver of the decision to issue by poorly capitalized banks.
To Pay or Be Paid? The Impact of Taker Fees and Order Flow Inducements on Trading Costs in U.S. Options Markets
Authors: Battalio Robert , Shkilko Andriy , Van Ness Robert
Published: December 2016

Consistent with prior literature, we find that average relative effective spreads are higher for venues that pay for order flow (PFOF) than for venues utilizing the maker-taker (MT) model. This relation becomes more nuanced when liquidity fees are incorporated into liquidity cost measures. For the majority of options, PFOF venues offer lower average liquidity costs net of taker fees. Net liquidity costs for the high-priced options, however, are lower for MT venues. Overall, our results suggest that the inclusion of fees and rebates can rationalize the routing of most, but not all, marketable orders to PFOF venues.
Blockholder Heterogeneity, CEO Compensation, and Firm Performance
Authors: Clifford Christopher P. , Lindsey Laura
Published: December 2016

This paper examines heterogeneity in blockholder monitoring across investor types. We document which blockholder types (e.g., mutual funds, hedge funds) are more likely to be associated with active monitoring and show that firms targeted by such blockholders are more likely to increase the equity portion of chief executive officer (CEO) pay. Further, using market-wide and exogenous shocks to liquidity to identify differences in efficacy across blockholder types, we observe greater operating-performance improvements in actively monitored firms when passive monitoring is less effective, suggesting causal impact. We propose differences in compensation arrangements across blockholder types as a mechanism underlying blockholders’ heterogeneous role.
Initial Public Offering Allocations, Price Support, and Secondary Investors
Authors: Fjesme Sturla Lyngnes
Published: December 2016

Tying initial public offering (IPO) allocations to after-listing purchases of other IPO shares as a form of price support has generated much theoretical interest and media attention. Price support is price manipulation and can reduce secondary investor return. In the past, obtaining data to investigate price support has proven to be difficult. I document that price support is harming secondary investor return using new data from the Oslo Stock Exchange. I also show that investors who engage in price support are allocated more future oversubscribed allocations, whereas harmed secondary investors significantly reduce their future participation in the secondary market.
Linkage to the CCM2 Locus and Genetic Heterogeneity in Familial Cerebral Cavernous Malformation
Authors: Dupré Nicolas , Verlaan Dominique J. , Hand Collette K. , Laurent Sandra B. , Turecki Gustavo , Davenport W. Jeptha , Acciarri Nicola , Dichgans Johannes , Ohkuma Akio , Siegel Adrian M. , Rouleau Guy A.
Published: December 2016

Background:

Cerebral cavernous malformation (CCM) is a form of intracranial vascular disease that may arise sporadically or be dominantly inherited. Linkage studies have revealed genetic heterogeneity among the dominantly inherited forms suggesting the existence of at least three loci called CCM1, CCM2 and CCM3.

Methods:

In the present study, we screened five families with dominantly inherited CCM for CCM1 gene mutations with denaturing high performance liquid chromatography (DHPLC). Then, we performed linkage analysis and haplotyping on these five families using highly polymorphic markers at the candidate CCM loci.

Results:

None of the five families tested with DHPLC were found to have mutations in the CCM1 gene. Based on haplotyping, we identified three families segregating alleles for CCM2, while two families segregated alleles for CCM3. Using linkage analysis, we could confirm that one family (IFCAS-1) had a positive Lod score of 2.03 (p<0.0001) at the CCM2 locus using marker D7S678.

Conclusions:

The present study is the first one to replicate linkage at the CCM2 locus and provides a fifth family identified as such. It also supports the concept of genetic heterogeneity in CCM, identifying four other families that showed no mutations in the CCM1 gene.
Dopamine Transporter Binding in Wilson's Disease
Authors: Huang Chin-Chang , Chu Nai-Shin , Yen Tzu-Chen , Wai Yau-Yau , Lu Chin-Song
Published: December 2016

Introduction:

In Wilson's disease (WD), brain magnetic resonance images (MRI) show increased signal intensity in T2 weighted images in the lenticular nuclei, thalamus and brainstem, including the substantia nigra. A poor therapeutic response to levodopa in WD suggests the mechanism of a postsynaptic abnormality. However positron emission tomography studies show an involvement of the nigrostriatal presynaptic dopaminergic pathway.

Case report:

We report the clinical manifestations in a case of WD with akinetic-rigid syndrome and initial hesitation. The brain MRI showed an increased signal intensity lesion in the substantia nigra region, in addition to basal ganglion and thalamic lesions. However, dopamine transporter (DAT) imaging with 99mTc-TRODAT-1 revealed a nonsignificantly increased DAT uptake, suggesting a normal presynaptic nigrostriatal dopaminergic terminal.

Conclusion:

We suggest that significant heterogeneity can be found in WD patients and a normal presynaptic dopaminergic pathway may occur in some patients, even those with typical akinetic-rigid syndrome and evidence of substantia nigra involvement in the brain on MRI.
Stanley Robert Hart Receives 2016 William Bowie Medal
Authors:   AGU
Published: December 2016

Stanley Robert Hart was awarded the 2016 William Bowie Medal at the American Geophysical Union Fall Meeting Honors Ceremony, held on 14 December 2016 in San Francisco, Calif. The medal is for "outstanding contributions for fundamental geophysics and for unselfish cooperation in research."
Efficient and recyclable Ir(i)-catalysts with the involvement of π-acceptor phosphines for N-alkylation of aryl amines with alcohols
Authors: Liu Huan , Wang Dong-Liang , Chen Xia , Lu Yong , Zhao Xiao-Li , Liu Ye
Published: December 2016

Efficient and recyclable Ir-catalysts with the involvement of ionic π-acceptor phosphines in ionic liquid solvent for N-alkylation of amines with alcohols.
Long-cycled Li2ZnTi3O8/TiO2 composite anode material synthesized via a one-pot co-precipitation method for lithium ion batteries
Authors: Li Hua , Li Zhoufu , Cui Yanhui , Ma Chenxiang , Tang Zhiyuan
Published: December 2016

Li2ZnTi3O8 and Li2ZnTi3O8/TiO2 anode materials were synthesized via a co-precipitation method and displayed excellent electrochemical performances.
Local structure and controllable thermal expansion in the solid solution (Mn1−xNix)ZrF6
Authors: Han Fei , Hu Lei , Liu Zhanning , Li Qiang , Wang Tao , Ren Yang , Deng Jinxia , Chen Jun , Xing Xianran
Published: December 2016

Controllable thermal expansion in the cubic solid solutions of (Mn1−xNix)ZrF6through atomic linkage flexibility.
Metal halide perovskite nanomaterials: synthesis and applications
Authors: Ha Son-Tung , Su Rui , Xing Jun , Zhang Qing , Xiong Qihua
Published: December 2016

The different synthesis approaches and growth mechanisms of metal halide perovskites will be discussed along with their novel characteristics and applications.
DDX3 directly regulates TRAF3 ubiquitination and acts as a scaffold to co-ordinate assembly of signalling complexes downstream from MAVS
Authors: Gu Lili , Fullam Anthony , McCormack Niamh , Höhn Yvette , Schröder Martina
Published: December 2016

The human DEAD-box helicase 3 (DDX3) has been shown to contribute to type I interferon (IFN) induction downstream from antiviral pattern recognition receptors. It binds to TANK-binding kinase 1 and IκB-kinase-ε (IKKε), the two key kinases mediating activation of IFN regulatory factor (IRF) 3 and IRF7. We previously demonstrated that DDX3 facilitates IKKε activation downstream from RIG-I and then links the activated kinase to IRF3. In the present study, we probed the interactions between DDX3 and other key signalling molecules in the RIG-I pathway and identified a novel direct interaction between DDX3 and TNF receptor-associated factor 3 (TRAF3) mediated by a TRAF-interaction motif in the N-terminus of DDX3, which was required for TRAF3 ubiquitination. Interestingly, we observed two waves of K63-linked TRAF3 ubiquitination following RIG-I activation by Sendai virus (SeV) infection, both of which were suppressed by DDX3 knockdown. We also investigated the spatiotemporal formation of endogenous downstream signalling complexes containing the mitochondrial antiviral signalling (MAVS) adaptor, DDX3, IκB-kinase-ε (IKKε), TRAF3 and IRF3. DDX3 was recruited to MAVS early after SeV infection, suggesting that it might mediate subsequent recruitment of other molecules. Indeed, knockdown of DDX3 prevented the formation of TRAF3–MAVS and TRAF3–IKKε complexes. Based on our data, we propose that early TRAF3 ubiquitination is required for the formation of a stable MAVS–TRAF3 complex, while the second wave of TRAF3 ubiquitination mediates IRF3 recruitment and activation. Our study characterises DDX3 as a multifunctional adaptor molecule that co-ordinates assembly of different TRAF3, IKKε and IRF3-containing signalling complexes downstream from MAVS. Additionally, it provides novel insights into the role of TRAF3 in RIG-I signalling.
Zero reduction codes for efficient transmission and enhanced brightness in visible light communication
Authors: Kim Kyuntak , Lee Kyujin , Lee Kyesan
Published: December 2016

In this study, the authors propose novel zero reduction codes to simultaneously provide effective illumination and communication services in visible light communications (VLC). In general, the brightness of light‐emitting diode illuminations can be enhanced by increasing the duty cycle ratio (DCR) but in such cases, the bit error rate (BER) performance is significantly degraded in the VLC systems. This is because the decision interference of received 0 and 1 bits is increased owing to the decision boundary overlapped. The proposed coding scheme can improve the brightness without increasing DCR and also achieve the enhanced BER performance compared to the conventional modulation schemes such as variable pulse‐position modulation or variable on–off keying. The simulations results demonstrate that the proposed coding scheme provides the superior brightness and BER performances.
Improving the wet chemical patterning of nichrome film by inserting an ultrathin titanium layer
Authors: Li Weizhi , Gou Jun , Wang Jun , Wei Xiongbang
Published: December 2016

We studied how to improve the quality of nichrome (NiCr) films patterned with wet chemical etching by inserting an ultrathin titanium film. The experimental results showed that inserting a 20-nm Ti layer between the photoresist (PR) and NiCr greatly improved the quality of the resultant pattern, which had minimal undercut and smooth edges. We attributed this improvement to the improved mask/NiCr interface, which we confirmed by scanning electron microscopy (SEM). In addition, we found that the undercutting of NiCr comprised two stages—an initial, relatively slow undercut stage and a second, faster stage—separated by the critical time point, the time at which the unmasked NiCr film etched away completely.
A versatile implementation of pulsed optical excitation in scanning tunneling microscopy
Authors: Kloth P. , Thias T. , Bunjes O. , von der Haar J. , Wenderoth M.
Published: December 2016

We present a combination of pulsed optical excitation and scanning tunneling microscopy with a highly flexible pulse generation method. A high frequency arbitrary wave generator drives a gigahertz electro-optical modulator, which processes a continuous-wave laser beam of a low-noise laser diode into the desired wave shape. For pump-probe excitation we generate optical pulse series in an all-electronic way. Thereby we can easily adapt parameters like pulse amplitude, width, or repetition cycle to the demands of the experiment. This setup is used to study different dynamic processes at the GaAs(110) surface. Separating thermally induced effects from electrically induced effects allows us to quantify the thermal contribution of the optical excitation in STM experiments. Time-resolved decay spectra of the photo-generated electron-hole pairs demonstrate the nanoscale spatial resolution.
Two-dimensional conformal field theories with matrix-valued level
Authors: Nassar Ali
Published: December 2016

We introduce a new class of two dimensional conformal field theories by extending Wess-Zumino-Witten (WZW) models to chiral algebras with matrix-valued levels. The new conformal field theories (CFTs) are based on holomorphic currents with an operator product expansion characterized by a positive integer-valued matrix KAB. We use the Sugawara construction to compute the energy-momentum tensor, the central charge, and the spectrum of conformal dimensions of the CFTs based on this algebra. We also construct a set of genus-1 characters and show that they fulfil a representation of the modular group SL(2, ℤ) up to a modular anomaly.
High order path integrals made easy
Authors: Kapil Venkat , Behler Jörg , Ceriotti Michele
Published: December 2016

The precise description of quantum nuclear fluctuations in atomistic modelling is possible by employing path integral techniques, which involve a considerable computational overhead due to the need of simulating multiple replicas of the system. Many approaches have been suggested to reduce the required number of replicas. Among these, high-order factorizations of the Boltzmann operator are particularly attractive for high-precision and low-temperature scenarios. Unfortunately, to date, several technical challenges have prevented a widespread use of these approaches to study the nuclear quantum effects in condensed-phase systems. Here we introduce an inexpensive molecular dynamics scheme that overcomes these limitations, thus making it possible to exploit the improved convergence of high-order path integrals without having to sacrifice the stability, convenience, and flexibility of conventional second-order techniques. The capabilities of the method are demonstrated by simulations of liquid water and ice, as described by a neural-network potential fitted to the dispersion-corrected hybrid density functional theory calculations.
Effects of the precursor electron bunch on quasi-phase matched direct laser acceleration
Authors: Lin M.-W. , Hsieh C.-Y. , Liu Y.-L. , Chen S.-H. , Jovanovic I.
Published: December 2016

Direct laser acceleration (DLA) of electrons can be achieved by utilizing the axial field of a well-guided, radially polarized laser pulse in a density-modulated plasma waveguide. When a laser pulse of a few terawatt (TW) peak power is applied, however, the laser ponderomotive force perturbs plasma electrons to concentrate in the center, such that the generated electrostatic fields can significantly defocus the externally injected electron witness bunch and considerably deteriorate the acceleration efficiency. To improve the performance of DLA, a leading electron bunch, which acts as a precursor, can be introduced in DLA to effectively confine the witness bunch. Three-dimensional particle-in-cell simulations have been conducted to demonstrate that the transverse properties of the witness bunch can be significantly improved when a precursor bunch is used. Selected bunch transverse sizes, bunch charges, and axial separation from the witness bunch have been assigned to the precursor in a series of DLA simulations. Since a favorable ion-focusing force is provided by the precursor, the transverse properties of witness bunch can be maintained when a relatively high-power (∼2 TW) laser pulse is used in DLA, and an improved overall acceleration efficiency can be achieved.
Evolution of supersonic corner vortex in a hypersonic inlet/isolator model
Authors: Huang He-Xia , Tan Hui-Jun , Sun Shu , Ling Yu
Published: December 2016

There are complex corner vortex flows in a rectangular hypersonic inlet/isolator. The corner vortex propagates downstream and interacts with the shocks and expansion waves in the isolator repeatedly. The supersonic corner vortex in a generic hypersonic inlet/isolator model is theoretically and numerically analyzed at a freestream Mach number of 4.92. The cross-flow topology of the corner vortex flow is found to obey Zhang’s theory [“Analytical analysis of subsonic and supersonic vortex formation,” Acta Aerodyn. Sin. 13, 259–264 (1995)] strictly, except for the short process with the vortex core situated in a subsonic flow which is surrounded by a supersonic flow. In general, the evolution history of the corner vortex under the influence of the background waves in the hypersonic inlet/isolator model can be classified into two types, namely, from the adverse pressure gradient region to the favorable pressure gradient region and the reversed one. For type 1, the corner vortex is a one-celled vortex with the cross-sectional streamlines spiraling inwards at first. Then the Hopf bifurcation occurs and the streamlines in the outer part of the limit cycle switch to spiraling outwards, yielding a two-celled vortex. The limit cycle shrinks gradually and finally vanishes with the streamlines of the entire corner vortex spiraling outwards. For type 2, the cross-sectional streamlines of the corner vortex spiral outwards first. Then a stable limit cycle is formed, yielding a two-celled vortex. The short-lived limit cycle forces the streamlines in the corner vortex to change the spiraling trends rapidly. Although it is found in this paper that there are some defects on the theoretical proof of the limit cycle, Zhang’s theory is proven useful for the prediction and qualitative analysis of the complex corner vortex in a hypersonic inlet/isolator. In addition, three conservation laws inside the limit cycle are obtained.
Comparison of pulsating DC and DC power air-water plasma jet: A method to decrease plume temperature and increase ROS
Authors: Liu K. , Hu H. , Lei J. , Hu Y. , Zheng Z.
Published: December 2016

Most air–water plasma jets are rich in hydroxyl radicals (•OH), but the plasma has higher temperatures, compared to that of pure gas, especially when using air as working gas. In this paper, pulsating direct current (PDC) power was used to excite the air–water plasma jet to reduce plume temperature. In addition to the temperature, other differences between PDC and DC plasma jets are not yet clear. Thus, comparative studies of those plasmas are performed to evaluate characteristics, such as breakdown voltage, temperature, and reactive oxygen species. The results show that the plume temperature of PDC plasma is roughly 5–10 °C lower than that of DC plasma in the same conditions. The •OH content of PDC is lower than that of DC plasma, whereas the O content of PDC plasma is higher. The addition of water leads in an increase in the plume temperature and in the production of •OH with two types of power supplies. The production of O inversely shows a declining tendency with higher water ratio. The most important finding is that the PDC plasma with 100% water ratio achieves lower temperature and more abundant production of •OH and O, compared with DC plasma with 0% water ratio.
Low energy electron-impact ionization of hydrogen atom for coplanar equal-energy-sharing kinematics in Debye plasmas
Authors: Li Jun , Zhang Song Bin , Ye Bang Jiao , Wang Jian Guo , Janev R. K.
Published: December 2016

Low energy electron-impact ionization of hydrogen atom in Debye plasmas has been investigated by employing the exterior complex scaling method. The interactions between the charged particles in the plasma have been represented by Debye-Hückel potentials. Triple differential cross sections (TDCS) in the coplanar equal-energy-sharing geometry at an incident energy of 15.6 eV for different screening lengths are reported. As the screening strength increases, TDCS change significantly. The evolutions of dominant typical peak structures of the TDCS are studied in detail for different screening lengths and for different coplanar equal-energy-sharing geometries.
Experimental investigations of the plasma radial uniformity in single and dual frequency capacitively coupled argon discharges
Authors: Zhao Kai , Liu Yong-Xin , Gao Fei , Liu Gang-Hu , Han Dao-Man , Wang You-Nian
Published: December 2016

In the current work, the radial plasma density has been measured by utilizing a floating double probe in single and dual frequency capacitively coupled argon discharges operated in a cylindrical reactor, aiming at a better understanding of electromagnetic effects and exploring a method of improving the radial uniformity. The experimental results indicate that for single-frequency plasma sustained at low pressure, the plasma density radial profile exhibits a parabolic distribution at 90 MHz, whereas at 180 MHz, the profile evolves into a bimodal distribution, and both cases indicate poor uniformities. With increasing the pressure, the plasma radial uniformity becomes better for both driving frequency cases. By contrast, when discharges are excited by two frequencies (i.e., 90 + 180 MHz), the plasma radial profile is simultaneously influenced by both sources. It is found that by adjusting the low-frequency to high-frequency voltage amplitude ratio β, the radial profile of plasma density could be controlled and optimized for a wide pressure range. To gain a better plasma uniformity, it is necessary to consider the balance between the standing wave effect, which leads to a maximum plasma density at the reactor center, and the edge field effect, which is responsible for a maximum density near the radial electrode edge. This balance can be controlled either by selecting a proper gas pressure or by adjusting the ratio β.
The effect of seed electrons on the repeatability of atmospheric pressure plasma plume propagation. II. Modeling
Authors: Chang L. , Nie L. , Xian Y. , Lu X.
Published: December 2016

One of the distinguishable features of plasma jets compared with the traditional streamers is their repeatable propagation. As an initial objective, the effect of seed electrons on the repeatability of plasma plume propagation is investigated numerically. Besides residual electrons left from previous pulses, the electrons detached from O2− ions could also be a significant source of the seed electrons to affect the repeatability of plasma plume propagation when an electronegative gas admixture is presented. In this investigation, a global plasma chemical kinetics model is developed to investigate the temporal evolution of the electron and O2− ions in the afterglow of a plasma plume driven by microsecond pulse direct current voltages, at a total gas pressure of 2 × 104 Pa or 4 × 103 Pa in helium or helium-oxygen mixtures with an air impurity of 0.025%. In addition, a Monte Carlo technique has been applied to calculate the O2− detachment rate coefficient. Accordingly, the seed electron density due to detachment from O2− ions for different percentages of oxygen is obtained. Finally, the minimum seed electron density required for the plasma bullets to propagate in a repeatable mode is obtained according to the critical frequency from the experiments. It is found that the order of minimum seed electron number density required for repeatable propagation mode is independent of oxygen concentrations in the helium-oxygen mixture. It is 108 cm−3 for 20 kPa and 107 cm−3 for 4 kPa. Furthermore, for the helium with an air impurity of 0.025%, the residual electrons left over from previous discharges are the main source of seed electrons. On the other hand, when 0.5% of O2 is added, the detachment of O2− is the main source of the seed electrons.
Effect of lens focusing distance on laser-produced copper plasma in air in the presence of static transverse magnetic field
Authors: Singh Khwairakpam Shantakumar , Sharma Ashwini Kumar
Published: December 2016

We report on the role of lens focusing conditions on laser-produced copper plasma in air at atmospheric pressure in the presence of magnetic field using optical emission spectroscopy. From the time integrated and temporal optical emission spectroscopy, we observed that the copper neutral/ionic line showed a higher intensity when the focal point of the lens was below the target surface in the absence of the magnetic field. In the presence of magnetic field, significant intensity enhancement was observed when the focal point was below the target surface which is attributed to an increase in the plasma-magnetic field interaction at this focusing condition. When the focal point was above the target surface, the intensity of neutral line was quite low and the effect of magnetic field was insignificant. This is because of air breakdown which caused lesser laser-matter interaction and eventually plasma-magnetic field interaction. Based on heat conduction equation, we also simulated the laser heating of copper target using a finite element method to predict the expansion velocity at different laser focusing conditions and the stopping radius of plasma and found that it depends on the distance between the focal point and the target surface. The intensity enhancement in the presence of magnetic field occurred at a stopping radius where the density of plasma was high due to considerable deceleration of the plasma by magnetic field.
In situ membrane bending setup for strain-dependent scanning transmission x-ray microscopy investigations
Authors: Finizio S. , Wintz S. , Kirk E. , Raabe J.
Published: December 2016

We present a setup that allows for the in situ generation of tensile strains by bending x-ray transparent Si3N4 membranes with the application of a pressure difference between the two sides of the membrane, enabling the possibility to employ high resolution space- and time-resolved scanning transmission x-ray microscopy for the investigation of the magneto-elastic coupling.
Surface chemical bonds, surface-enhanced Raman scattering, and dielectric constant of SiO2 nanospheres in-situ decorated with Ag-nanoparticles by electron-irradiation
Authors: Phatangare A. B. , Dhole S. D. , Dahiwale S. S. , Mathe V. L. , Bhoraskar S. V. , Late D. J. , Bhoraskar V. N.
Published: December 2016

Nanostructures of dielectric materials decorated with metal nanoparticles are of great scientific interest; however, the involved synthesis methods are complicated and require multistep chemical processing, including functionalization of the dielectric surfaces. In the present work, without chemical processes, silver nanoparticles of average sizes in the range of 11 to 15 nm were in-situ synthesized and decorated on SiO2 nanospheres in a single step process by irradiating a solution (AgNO3–polyvinylpyrrolidone (PVP)–SiO2 nanospheres) with 6 MeV electrons at 1.5 × 1015 e−/cm2, 3.0 × 1015 e−/cm2, and 4.5 × 1015 e−/cm2 fluences. The electron irradiated solutions were characterized with different surface and other techniques. The results revealed that the SiO2 nanospheres were uniformly decorated with Ag nanoparticles, and the prominent chemical bonds involved were Ag–O, Si–O–Ag, and Si–Ag. Moreover, the sizes and the decoration density of Ag nanoparticles could be tailored by varying electron fluence. The Surface-enhanced Raman scattering (SERS) of 4-aminothiophenol (4-ATP) solutions was studied using substrates in the form of thin coatings of the solutions of Ag-decorated SiO2 nanospheres. The appearance of the characteristic SERS peaks of both 4-ATP and 4, 4′-dimercaptoazobenzene (4, 4′-DMAB) in Raman spectra confirmed the conversion of a fraction of 4-ATP into 4, 4′-DMAB in the presence of Ag nanoparticles. Composites in the form of thin films were synthesized from the mixture solutions of PVP and Ag-decorated SiO2 nanospheres. The dielectric constant of each thin film was higher as compared to polymers, and could be tailored by varying electron fluence used for decorating Ag nanoparticles.
Skyrmion-number dependence of spin-transfer torque on magnetic bubbles
Authors: Yamane Yuta , Sinova Jairo
Published: December 2016

We theoretically study the skyrmion-number dependence of spin-transfer torque acting on magnetic bubbles. The skymrion number of magnetic bubbles can take any integer value depending on the magnetic profile on its circumference and the size of the bubble. We find that the transverse motion of a bubble with respect to the charge current is greatly suppressed as the absolute value of the skyrmion number departs from unity, whereas the longitudinal motion is less sensitive.
Sequential time interleaved random equivalent sampling for repetitive signal
Authors: Zhao Yijiu , Liu Jingjing
Published: December 2016

Compressed sensing (CS) based sampling techniques exhibit many advantages over other existing approaches for sparse signal spectrum sensing; they are also incorporated into non-uniform sampling signal reconstruction to improve the efficiency, such as random equivalent sampling (RES). However, in CS based RES, only one sample of each acquisition is considered in the signal reconstruction stage, and it will result in more acquisition runs and longer sampling time. In this paper, a sampling sequence is taken in each RES acquisition run, and the corresponding block measurement matrix is constructed using a Whittaker-Shannon interpolation formula. All the block matrices are combined into an equivalent measurement matrix with respect to all sampling sequences. We implemented the proposed approach with a multi-cores analog-to-digital converter (ADC), whose ADC cores are time interleaved. A prototype realization of this proposed CS based sequential random equivalent sampling method has been developed. It is able to capture an analog waveform at an equivalent sampling rate of 40 GHz while sampled at 1 GHz physically. Experiments indicate that, for a sparse signal, the proposed CS based sequential random equivalent sampling exhibits high efficiency.
Enhanced frequency upconversion in Ho3+/Yb3+/Li+:YMoO4 nanophosphors for photonic and security ink applications
Authors: Mondal Manisha , Kumar Rai Vineet , Srivastava Chandan , Sarkar Suman , Akash R.
Published: December 2016

The YMoO4 nanophosphors codoped with Ho3+/Yb3+/Li+ ions synthesized by the chemical coprecipitation method have been structurally characterized by using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy (TEM) techniques. The TEM bright field imaging shows that the developed nanophosphors are crystalline in nature with particle size ∼45 nm. The upconversion (UC) emission spectra upon excitation at 980 nm of the nanophosphors at low pump power (<900 mW) show the emission peaks in the UV, green, and red regions, whereas at high pump power (≥900 mW) an intense broad band ranging from 400–900 nm along with a UV band has been observed. The enhancement of about ∼104 times corresponding to the green band in the Ho3+-Yb3+-Li+ codoped nanophosphors compared to that of the Ho3+ singly doped nanophosphors has been observed. This enhancement is caused by the energy transfer from the Yb3+ to Ho3+ ions and modified the local crystal field developed around the rare earth ions. A higher value of the slope (i.e., n ∼ 6.38) for broad band emission within the 944 mW-1200 mW pump power region in the Ho3+-Yb3+-Li+ codoped nanophosphors is found to be due to the involvement of the photon avalanche population process but it is not related to the black body radiation. The intense peak at ∼564 nm and ∼648 nm for the broad band emission is attributed to the charge transfer luminescence of codoped nanophosphors, which is related to the oxygen ion present in the MoO4 group and Yb3+ ion. The observations described in this paper may be of significant interest for developing the visible upconverters, security ink, and novel devices for displays in the low and high pump power region.
Systematic study on dynamic atomic layer epitaxy of InN on/in +c-GaN matrix and fabrication of fine-structure InN/GaN quantum wells: Impact of excess In-atoms at high growth temperature
Authors: Yoshikawa Akihiko , Kusakabe Kazuhide , Hashimoto Naoki , Imai Daichi , Hwang Eun-Sook
Published: December 2016

The growth kinetics of nominally one-monolayer (∼1-ML)-thick InN wells on/in the +c-GaN matrix fabricated using dynamic atomic layer epitaxy (D-ALEp) by plasma-assisted molecular beam epitaxy were systematically studied, with particular attention given to the impacts of excess In atoms and/or In droplets at a high growth temperature of 650 °C. Even at a constant growth temperature of 650 °C, the thickness of the sheet-island-like InN-well layers could be controlled/varied from 1-ML to 2-ML owing to the effect of excess In atoms and/or In droplets accumulated during growth. The possible growth mechanism is discussed based on the ring-shaped bright cathodoluminescence emissions introduced along the circumference of the In droplets during growth. The effective thermal stability of N atoms below the bilayer adsorbed In atoms was increased by the presence of In droplets, resulting in the freezing of 2-ML-thick InN wells into the GaN matrix. It therefore became possible to study the difference between the emission properties of 1-ML and 2-ML-thick InN wells/GaN matrix quantum wells (QWs) having similar GaN matrix crystallinity grown at the same temperature. InN/GaN QW-samples grown under widely different In + N* supply conditions characteristically separated into two groups with distinctive emission-peak wavelengths originating from 1-ML and 2-ML-thick InN wells embedded in the GaN matrix. Reflecting the growth mechanism inherent to the D-ALEp of InN on/in the +c-GaN matrix at high temperature, either 1-ML or 2-ML-thick “binary” InN well layers tended to be frozen into the GaN matrix rather InGaN random ternary-alloys. Both the structural quality and uniformity of the 1-ML InN well sample were better than those of the 2-ML InN well sample, essentially owing to the quite thin critical thickness of around 1-ML arising from the large lattice mismatch of InN and GaN.
Charged grain boundaries reduce the open-circuit voltage of polycrystalline solar cells—An analytical description
Authors: Gaury Benoit , Haney Paul M.
Published: December 2016

Analytical expressions are presented for the dark current-voltage relation J(V) of a pn+ junction with positively charged columnar grain boundaries with high defect density. These expressions apply to non-depleted grains with sufficiently high bulk hole mobilities. The accuracy of the formulas is verified by direct comparison to numerical simulations. Numerical simulations further show that the dark J(V) can be used to determine the open-circuit potential Voc of an illuminated junction for a given short-circuit current density Jsc. A precise relation between the grain boundary properties and Voc is provided, advancing the understanding of the influence of grain boundaries on the efficiency of thin film polycrystalline photovoltaics like CdTe and Cu(In,Ga)Se2.
Lateral amorphous selenium metal-insulator-semiconductor-insulator-metal photodetectors using ultrathin dielectric blocking layers for dark current suppression
Authors: Chang Cheng-Yi , Pan Fu-Ming , Lin Jian-Siang , Yu Tung-Yuan , Li Yi-Ming , Chen Chieh-Yang
Published: December 2016

We fabricated amorphous selenium (a-Se) photodetectors with a lateral metal-insulator-semiconductor-insulator-metal (MISIM) device structure. Thermal aluminum oxide, plasma-enhanced chemical vapor deposited silicon nitride, and thermal atomic layer deposited (ALD) aluminum oxide and hafnium oxide (ALD-HfO2) were used as the electron and hole blocking layers of the MISIM photodetectors for dark current suppression. A reduction in the dark current by three orders of magnitude can be achieved at electric fields between 10 and 30 V/μm. The effective dark current suppression is primarily ascribed to electric field lowering in the dielectric layers as a result of charge trapping in deep levels. Photogenerated carriers in the a-Se layer can be transported across the blocking layers to the Al electrodes via Fowler-Nordheim tunneling because a high electric field develops in the ultrathin dielectric layers under illumination. Since the a-Se MISIM photodetectors have a very low dark current without significant degradation in the photoresponse, the signal contrast is greatly improved. The MISIM photodetector with the ALD-HfO2 blocking layer has an optimal signal contrast more than 500 times the contrast of the photodetector without a blocking layer at 15 V/μm.
Electronic properties of the residual donor in unintentionally doped β-Ga2O3
Authors: Son N. T. , Goto K. , Nomura K. , Thieu Q. T. , Togashi R. , Murakami H. , Kumagai Y. , Kuramata A. , Higashiwaki M. , Koukitu A. , Yamakoshi S. , Monemar B. , Janzén E.
Published: December 2016

Electron paramagnetic resonance was used to study the donor that is responsible for the n-type conductivity in unintentionally doped (UID) β-Ga2O3 substrates. We show that in as-grown materials, the donor requires high temperature annealing to be activated. In partly activated materials with the donor concentration in the 1016 cm−3 range or lower, the donor is found to behave as a negative-U center (often called a DX center) with the negative charge state DX− lying ∼16–20 meV below the neutral charge state d0 (or Ed), which is estimated to be ∼28–29 meV below the conduction band minimum. This corresponds to a donor activation energy of Ea∼44–49 meV. In fully activated materials with the donor spin density close to ∼1 × 1018 cm−3, donor electrons become delocalized, leading to the formation of impurity bands, which reduces the donor activation energy to Ea∼15–17 meV. The results clarify the electronic structure of the dominant donor in UID β-Ga2O3 and explain the large variation in the previously reported donor activation energy.
Experimental studies of breakdown characteristics in pulse-modulated radio-frequency atmospheric discharge
Authors: Huo W. G. , Zhang X. , Gu J. L. , Ding Z. F.
Published: December 2016

The influences of the pulse off-time on the breakdown voltage of the first pulse and the stable pulse discharge (having repeatedly undergone a process of ignition, maintenance, and extinction) are experimentally investigated in a pulse-modulated radio-frequency atmospheric pressure argon discharge. The experimental results show that the first pulse discharge breakdown voltage decreases, but the stable pulse discharge breakdown voltage increases with increasing the pulse off-time. In a large region of the pulse off-time, the luminescence property of the initial breakdown stage is studied using a high speed camera. The captured images at different pulse off-times demonstrate that the gas breakdown exhibits five key characteristics: single-point random breakdown, multi-point random breakdown, stable uniform breakdown, stable glow mixed with pattern breakdown, and stable nonuniform pattern breakdown. The physical reasons for these results are discussed.
Cross-sections for neutral atoms and molecules collisions with charged spherical nanoparticle
Authors: Shneider M. N.
Published: December 2016

This paper presents cross sections for collisions of neutral atoms/molecules with a charged spherical nanoparticle, which is the source of the dipole potential. The accuracy of the orbital limited motion (OLM) approximation is estimated. It is shown that simple analytical formulas for the atoms/molecules and heat fluxes, obtained in the OLM approximation, give an error of not more than 15% and are applicable in all reasonable range of nanoparticles and weakly ionized plasma parameters.
Insights into electrode/electrolyte interfacial processes and the effect of nanostructured cobalt oxides loading on graphene-based hybrids by scanning electrochemical microscopy
Authors: Gupta Sanju , Carrizosa Sara B.
Published: December 2016

Nanostructured cobalt oxide polymorphs (CoO and Co3O4) deposited via electrodeposition allowed optimal loading on supercapacitive graphene nanosheets producing a set of graphene-based hybrids namely, CoO/GO, CoO/ErGO, Co3O4/GO, Co3O4/rGO, and Co3O4/ErGO, as pseudocapacitive electrochemical electrodes. We gained fundamental insights into the complex physicochemical interfacial processes at electrode surfaces and electrode/electrolyte (or solid/liquid) interfaces by scanning electrochemical microscopy operating in the feedback probe approach and imaging modes while monitoring and mapping the redox probe (re)activity behavior. We determined the various experimental descriptors including diffusion coefficient, electron transfer rate, and electroactive site distribution on electrodes. We emphasize the interplay of (1) heterogeneous basal and edge plane active sites, (2) graphene surface functional moieties (conducting/semiconducting), and (3) crystalline spinel cobalt oxides (semiconducting/insulating) coated graphene, reinforcing the available electron density of states in the vicinity of the Fermi level contributing to higher electroactivity, faster interfacial diffusion, and shorter distances for electron transfer, facilitated through molecular and chemical bridges obtained by electrodeposition as compared with the physical deposition.
GaN-based vertical-cavity surface emitting lasers with sub-milliamp threshold and small divergence angle
Authors: Yeh P. S. , Chang C.-C. , Chen Y.-T. , Lin D.-W. , Liou J.-S. , Wu C. C. , He J. H. , Kuo H.-C.
Published: December 2016

A GaN-based vertical-cavity surface emitting laser (VCSEL) structure featuring a silicon-diffusion-defined current blocking layer for lateral confinement is described. Sub-milliamp threshold currents were achieved for both 3- and 5-μm-aperture VCSELs under continuous-wave operation at room temperature. The vertical cavity was defined by a top dielectric distributed Bragg reflector (DBR) and a bottom epitaxial DBR. The emission spectrum exhibited a single peak at 411.2 nm with a linewidth of 0.4 nm and a side mode suppression ratio of more than 10 dB before device packaging. The full-width-at-half-maximum divergence angle of the 3-μm-aperture VCSEL was as small as approximately 5° which is the lowest number reported. These results implied the 3-μm-aperture VCSEL was in near single-mode operation.
Capacitance evaluation of compact silicon triple quantum dots by simultaneous gate voltage sweeping
Authors: Uchida Takafumi , Jo Mingyu , Tsurumaki-Fukuchi Atsushi , Arita Masashi , Fujiwara Akira , Takahashi Yasuo
Published: December 2016

We propose a simple method to evaluate the triple quantum dots (TQDs) coupled in series with the compact device structure. Compact coupled quantum dots, each with an attached control gate, offer promising applications as quantum computing and single-electron transfer devices. However, device reduction required in practical applications creates a capacitive cross-talk between a control gate and its neighboring dots making it difficult to determine the charge transition boundaries in each dot. To properly evaluate the electron-transfer characteristics of TQDs, a method is proposed whereby the three gate voltages are simultaneously swept. We studied the charge stability diagram of the compact TQDs using Monte Carlo simulations, and confirmed the effectiveness of the method. Compact Si-TQDs were actually fabricated by the use of pattern-dependent oxidation and additional oxidation method for this study. The method was then applied to the stability diagrams obtained from the devices. The nine measurements of the gate capacitances between the three sets of dots and gates were reproduced, confirming the formation of the TQDs.
A model for pressurized hydrogen induced thin film blisters
Authors: van den Bos R. A. J. M. , Reshetniak V. , Lee C. J. , Benschop J. , Bijkerk F.
Published: December 2016

We introduce a model for hydrogen induced blister formation in nanometer thick thin films. The model assumes that molecular hydrogen gets trapped under a circular blister cap causing it to deflect elastically outward until a stable blister is formed. In the first part, the energy balance required for a stable blister is calculated. From this model, the adhesion energy of the blister cap, the internal pressure, and the critical H-dose for blister formation can be calculated. In the second part, the flux balance required for a blister to grow to a stable size is calculated. The model is applied to blisters formed in a Mo/Si multilayer after being exposed to hydrogen ions. From the model, the adhesion energy of the Mo/Si blister cap was calculated to be around 1.05 J/m2 with internal pressures in the range of 175–280 MPa. Based on the model, a minimum ion dose for the onset of blister formation was calculated to be d = 4.2 × 1018 ions/cm2. From the flux balance equations, the diffusion constant for the Mo/Si blister cap was estimated to be DH2=(10±1)×10−18 cm2/s.
General formulation of rovibrational kinetic energy operators and matrix elements in internal bond-angle coordinates using factorized Jacobians
Authors: Kopp Wassja A. , Leonhard Kai
Published: December 2016

We show how inverse metric tensors and rovibrational kinetic energy operators in terms of internal bond-angle coordinates can be obtained analytically following a factorization of the Jacobian worked out by Frederick and Woywod. The structure of these Jacobians is exploited in two ways: On one hand, the elements of the metric tensor as well as its determinant all have the form ∑rmsin(αn)cos(βo). This form can be preserved by working with the adjugate metric tensor that can be obtained without divisions. On the other hand, the adjugate can be obtained with less effort by exploiting the lower triangular structure of the Jacobians. Together with a suitable choice of the wavefunction, we avoid singularities and show how to obtain analytical expressions for the rovibrational kinetic energy matrix elements.