bluuebunny/crossref_metadata_2025 huggingface dataset:
Seniority number in spin-adapted spaces and compactness of configuration interaction wave functions
Authors: Alcoba Diego R. , Torre Alicia , Lain Luis , Massaccesi Gustavo E. , Oña Ofelia B.
Published: August 2013

This work extends the concept of seniority number, which has been widely used for classifying N-electron Slater determinants, to wave functions of N electrons and spin S, as well as to N-electron spin-adapted Hilbert spaces. We propose a spin-free formulation of the seniority number operator and perform a study on the behavior of the expectation values of this operator under transformations of the molecular basis sets. This study leads to propose a quantitative evaluation for the convergence of the expansions of the wave functions in terms of Slater determinants. The non-invariant character of the seniority number operator expectation value of a wave function with respect to a unitary transformation of the molecular orbital basis set, allows us to search for a change of basis which minimizes that expectation value. The results found in the description of wave functions of selected atoms and molecules show that the expansions expressed in these bases exhibit a more rapid convergence than those formulated in the canonical molecular orbital bases and even in the natural orbital ones.
Some classes of renormalizable tensor models
Authors: Geloun Joseph Ben , Livine Etera R.
Published: August 2013

We identify new families of renormalizable tensor models from anterior renormalizable tensor models via a mapping capable of reducing or increasing the rank of the theory without having an effect on the renormalizability property. Mainly, a version of the rank 3 tensor model as defined by Ben Geloun and Samary [Ann. Henri Poincare 14, 1599 (2013); e-print arXiv:1201.0176 [hep-th]]10.1007/s00023-012-0225-5 and the Grosse-Wulkenhaar model in 4D and 2D generate three different classes of renormalizable models. The proof of the renormalizability is fully performed for the first reduced model. The same procedure can be applied for the remaining cases. Interestingly, we find that, due to the peculiar behavior of anisotropic wave function renormalizations, the rank 3 tensor model reduced to a matrix model generates a simple super-renormalizable vector model.
Experimental study of the effect of surface-absorbed hydrophobic particles on the Landau-Levich law
Authors: Ouriemi M. , Homsy G. M.
Published: August 2013

We study the dip coating of liquids with particles absorbed on the interface under controlled conditions to obtain data on the coating thickness of particle dispersions as a function of coating speed, physical properties, and particle surface concentration. The thickness of the coating film created by the withdrawal of a plate from a bath was measured gravimetrically over a wide range of capillary numbers for two different kinds of particles. It is found that the presence of particles results in a significant thickening of the film relative to that for a clean interface, and in a slightly different power law for the thickness vs. capillary number than the classical Landau-Levich law. The influence of the particle surface concentration is also investigated, and shows a strong dependence of the film thickness on concentration, including a threshold concentration at which the film thickness begins to deviate from that for a clean interface.
Plasma diagnostic method using intermodulation frequencies in a Langmuir probe
Authors: Kim Dong-Hwan , Lee Hyo-Chang , Kim Yu-Sin , Chung Chin-Wook
Published: August 2013

A plasma diagnostic method using intermodulation frequencies is developed. When dual-frequency (ω1,ω2) voltage signals are applied to a probe, the intermodulation frequencies (ω2±ω1, ω2±2ω1) between the signals are generated due to the nonlinearity of the sheath. From the analysis of the intermodulation frequencies, the plasma parameters, such as the electron temperature and the plasma density, can be obtained. The measured plasma parameters from this method are compared to the results from the measured electron energy distribution function, and they are in good agreement. Because the intermodulation currents originated from the plasma not from the stray component of the measurement system, an accurate measurement of the plasma parameters is achievable.
Ultrafast coherent control of giant oscillating molecular dipoles in the presence of static electric fields
Authors: Chang Bo Y. , Shin Seokmin , Palacios Alicia , Martín Fernando , Sola Ignacio R.
Published: August 2013

We propose a scheme to generate electric dipole moments in homonuclear molecular cations by creating, with an ultrashort pump pulse, a quantum superposition of vibrational states on electronic states strongly perturbed by very strong static electric fields. By field-induced molecular stabilization, the dipoles can reach values as large as 50 Debyes and oscillate on a time-scale comparable to that of the slow vibrational motion. We show that both the electric field and the pump pulse parameters can be used to control the amplitude and period of the oscillation, while preventing the molecule from ionizing or dissociating.
Invited Article: A review of haptic optical tweezers for an interactive microworld exploration
Authors: Pacoret Cécile , Régnier Stéphane
Published: August 2013

This paper is the first review of haptic optical tweezers, a new technique which associates force feedback teleoperation with optical tweezers. This technique allows users to explore the microworld by sensing and exerting picoNewton-scale forces with trapped microspheres. Haptic optical tweezers also allow improved dexterity of micromanipulation and micro-assembly. One of the challenges of this technique is to sense and magnify picoNewton-scale forces by a factor of 1012 to enable human operators to perceive interactions that they have never experienced before, such as adhesion phenomena, extremely low inertia, and high frequency dynamics of extremely small objects. The design of optical tweezers for high quality haptic feedback is challenging, given the requirements for very high sensitivity and dynamic stability. The concept, design process, and specification of optical tweezers reviewed here are focused on those intended for haptic teleoperation. In this paper, two new specific designs as well as the current state-of-the-art are presented. Moreover, the remaining important issues are identified for further developments. The initial results obtained are promising and demonstrate that optical tweezers have a significant potential for haptic exploration of the microworld. Haptic optical tweezers will become an invaluable tool for force feedback micromanipulation of biological samples and nano- and micro-assembly parts.
Density functional theory study of Fe adatoms adsorbed monolayer and bilayer MoS2 sheets
Authors: Huang Zongyu , Hao Guolin , He Chaoyu , Yang Hong , Xue Lin , Qi Xiang , Peng Xiangyang , Zhong Jianxin
Published: August 2013

Functionalization of MoS2 sheet (monolayer and bilayer) by the adsorption of transition metal Fe adatom to its surface and interlayer has been investigated computationally using first-principles calculations based on the density functional theory. We found that the systems with absorption of Fe adatoms on the surfaces of both monolayer and bilayer MoS2 sheets are still semiconductors, without spin polarization at the Fermi level. However, for the system with absorption of Fe adatom in the interlayer of bilayer MoS2 sheet, its electronic structure exhibits half-metal behavior, with 100% spin polarization at the Femi level, which provides a promising material for spintronic devices.
Electrical and dielectric properties of silver iodide doped selenium molybdate glassy conductors
Authors: Palui A. , Deb B. , Ghosh A.
Published: August 2013

Electrical conductivity and dielectric properties of silver iodide doped silver ion mixed-former conducting glasses have been studied in this paper. The frequency dependence of conductivity has been analyzed following the random free-energy barrier model. The charge carrier relaxation time and the activation energy for relaxation have been determined for the present glasses. The applicability of Barton-Nakajima-Namikawa relation has been tested for the present glasses using the results obtained from random free-energy barrier model. The scaling of the conductivity spectra has been performed to understand the effect of temperature as well as composition on the relaxation dynamics. The dielectric data have been analyzed employing the Cole-Cole function, and parameters such as dielectric strength and Cole-Cole exponent have been obtained. The electrode polarization phenomenon for the present glass samples has been studied depending on temperature as well as composition. The different characteristic transitions concerning electrode polarization related to the charge transport at the interface have been obtained and are correlated to the bulk behavior. An estimation of the dc conductivity has been obtained using the result obtained from electrode polarization study and is observed to be very close to the experimental values.
A non-contact method based on multiple signal classification algorithm to reduce the measurement time for accurately heart rate detection
Authors: Bechet P. , Mitran R. , Munteanu M.
Published: August 2013

Non-contact methods for the assessment of vital signs are of great interest for specialists due to the benefits obtained in both medical and special applications, such as those for surveillance, monitoring, and search and rescue. This paper investigates the possibility of implementing a digital processing algorithm based on the MUSIC (Multiple Signal Classification) parametric spectral estimation in order to reduce the observation time needed to accurately measure the heart rate. It demonstrates that, by proper dimensioning the signal subspace, the MUSIC algorithm can be optimized in order to accurately assess the heart rate during an 8–28 s time interval. The validation of the processing algorithm performance was achieved by minimizing the mean error of the heart rate after performing simultaneous comparative measurements on several subjects. In order to calculate the error the reference value of heart rate was measured using a classic measurement system through direct contact.
New stability conditions for mixed linear Levin-Nohel integro-differential equations
Authors: Dung Nguyen Tien
Published: August 2013

For the mixed Levin-Nohel integro-differential equation, we obtain new necessary and sufficient conditions of asymptotic stability. These results improve those obtained by Becker and Burton [“Stability, fixed points and inverse of delays,” Proc. - R. Soc. Edinburgh, Sect. A 136, 245–275 (2006)]10.1017/S0308210500004546 and Jin and Luo [“Stability of an integro-differential equation,” Comput. Math. Appl. 57(7), 1080–1088 (2009)]10.1016/j.camwa.2009.01.006 when b(t) = 0 and supplement the \documentclass[12pt]{minimal}\begin{document}$\frac{3}{2}$\end{document}32-stability theorem when a(t, s) = 0. In addition, the case of the equations with several delays is discussed as well.
Standoff detection of hidden objects using backscattered ultra-intense laser-produced x-rays
Authors: Kuwabara H. , Mori Y. , Kitagawa Y.
Published: August 2013

Ultra-intense laser-produced sub-ps X-ray pulses can detect backscattered signals from objects hidden in aluminium containers. Coincident measurements using primary X-rays enable differentiation among acrylic, copper, and lead blocks inside the container. Backscattering reveals the shapes of the objects, while their material composition can be identified from the modification methods of the energy spectra of backscattered X-ray beams. This achievement is an important step toward more effective homeland security.
Heat generated by electrical current in a mesoscopic system perturbed by alternating current fields
Authors: Chen Qiao , Tang Li-Ming , Chen Ke-Qiu , Zhao Hong-Kang
Published: August 2013

To analyze heat generation in a quantum dot coupled to normal leads and subject to an ac field, a formula is derived for the heat generated Q using the nonequilibrium Keldysh Green's function technique. The numerical results show that the external ac field influences significantly the heat generated. The threshold bias decreases to Vt=ω0−nω through photon absorption. Additional steps emerge from photon-assisted tunneling, and the width of the step is equal to the frequency of photon ω and the height increases with the magnitude of the ac field. For large V/ω, the Q/ω curves display many resonant peaks due to multi-photon absorptions and emissions. Moreover, a negative differential heat generation can be observed as ω>ω0.
Negative thermoelectric power from large diameter multiwalled carbon nanotubes grown at high chemical vapor deposition temperatures
Authors: Hewitt Corey A. , Kaiser Alan B. , Craps Matt , Czerw Richard , Carroll David L.
Published: August 2013

Multiwalled carbon nanotubes (MWNTs) have been grown using a standard chemical vapor deposition method, except for varying the growth temperature. Nanotubes grown below 770 °C exhibit typical positive thermoelectric powers, while those grown above have negative values. This behavior is attributed to the larger nanotube diameters observed at higher growth temperatures. Below 770 °C, the average nanotube diameter is about 50 nm, while above, nanotubes reach diameters of 300 nm. This increase in diameter and number of inner shells leads to the intrinsic negative thermoelectric power of the inner nanotube shells becoming larger than the positive thermoelectric power due to oxygen doping on the outer surface of the nanotube. The overall negative thermopower (about −6 μV/K, compared to +7 μV/K for smaller diameter nanotubes) can be understood in terms of a parallel conduction model. Our large-diameter multiwalled carbon nanotubes allow the intrinsic negative thermopower of MWNTs to be accessed without requiring specific deoxygenation treatment.
Note: A multifunctional electrospinning system for manufacturing diversified nanofibrous structures
Authors: Ru Changhai , Wang Feilong , Ge Cuicui , Luo Jun
Published: August 2013

A multifunctional electrospinning system has been developed to fabricate diversified nanofibrous structures. It consists of a high voltage power supply, a syringe pump, and a cage like collector that are dominated via the controller by setting parameters from a touch screen. As the key component, speed, and diameter of the collector can be adjusted automatically according to predetermined requirement, which enhances the flexibility of the system. Well-aligned nanofiber array, nanofibrous membrane, and 3D nanofibrous structure were obtained successfully through the technique. This work should be of help to construct functional nanofibrous materials for promoting the development of electrospinning.
A non-discrete method for computation of residence time in fluid mechanics simulations
Authors: Esmaily-Moghadam Mahdi , Hsia Tain-Yen , Marsden Alison L.
Published: August 2013

Cardiovascular simulations provide a promising means to predict risk of thrombosis in grafts, devices, and surgical anatomies in adult and pediatric patients. Although the pathways for platelet activation and clot formation are not yet fully understood, recent findings suggest that thrombosis risk is increased in regions of flow recirculation and high residence time (RT). Current approaches for calculating RT are typically based on releasing a finite number of Lagrangian particles into the flow field and calculating RT by tracking their positions. However, special care must be taken to achieve temporal and spatial convergence, often requiring repeated simulations. In this work, we introduce a non-discrete method in which RT is calculated in an Eulerian framework using the advection-diffusion equation. We first present the formulation for calculating residence time in a given region of interest using two alternate definitions. The physical significance and sensitivity of the two measures of RT are discussed and their mathematical relation is established. An extension to a point-wise value is also presented. The methods presented here are then applied in a 2D cavity and two representative clinical scenarios, involving shunt placement for single ventricle heart defects and Kawasaki disease. In the second case study, we explored the relationship between RT and wall shear stress, a parameter of particular importance in cardiovascular disease.
Interactions of twin boundaries with intrinsic point defects and carbon in silicon
Authors: Käshammer Peter , Sinno Talid
Published: August 2013

Although multicrystalline silicon (mc-Si) is currently the most widely used material for fabricating photovoltaic cells, its electrical properties remain limited by several types of defects, which interact in complex ways that are not yet fully understood. A particularly important phenomenon is the interaction between grain boundaries and intrinsic point defects or impurity atoms, such as carbon, oxygen, nitrogen, and various types of metals. Here, we use empirical molecular dynamics to study the interactions of Σ3{111}, Σ9{221}, and Σ27{552} twin boundaries, which account for over 50% of all grain boundaries in mc-Si, with self-interstitials, vacancies, and substitutional carbon atoms. It is shown that twin boundary-point defect interaction energies increase with twinning order and that they are predominantly attractive. We also find that twin boundary interactions with substitutional carbon are highly spatially heterogeneous, exhibiting alternating repulsive-attractive regions that correlate strongly with the local bonding network. A robust picture is obtained by comparing predictions across a total of five different empirical potentials.
Design guidelines for slanting silicon nanowire arrays for solar cell application
Authors: Hong Lei , Rusli  , Wang Xincai , Zheng Hongyu , Wang Hao , Yu HongYu
Published: August 2013

The reflectance and absorption characteristics of slanting silicon nanowires (SiNWs) structure have been simulated using finite element method to provide a design guideline for its application in solar cell. The slanting angle for the nanowire structure is set at 40° on Si (111) wafer. The impact of the structural periodicity (P) and wire diameter/periodicity (D/P) ratio on the optical characteristics of the slanting SiNW has been systematically analyzed. It has been found that due to the much suppressed light reflection and stronger light trapping ability, the light absorption is significantly enhanced for the slanting SiNW structure compared with vertical SiNW structure. The optimal absorption condition is achieved when P = 800 nm and D/P = 0.7, yielding the highest ultimate efficiency of 33.45%. The result is better than the 28.36% that can be achieved for optimum vertical SiNWs. A comparison of the absorption characteristics of optimum slanting and vertical SiNWs structures is presented and analyzed in terms of the physical light interaction with the structures.
Competitive Si and La effect in HfO2 phase stabilization in multi-layer (La2O3)0.08(HfO2) films
Authors: Cao Duo , Cheng Xinhong , Yu Yuehui , Li Xiaolong , Liu Chunze , Shen Dashen , Mändl Stephan
Published: August 2013

The effect of Si diffusion in HfO2 and the presence of La on phase transformation were investigated. Tetragonal HfO2 structures exhibited high permittivity, and the addition of exotic atoms to HfO2 facilitated tetragonal phase transformation. In multi-layer (La2O3)0.08(HfO2) films, the top HfO2 layer was transformed into a perfect tetragonal structure, and the bottom HfO2 layer near the interfacial layer was of a cubic structure, after annealing at 800 °C. The permittivity reached 50–60. Si diffusion into the HfO2 film stabilized the tetragonal structure, and La incorporation into HfO2 facilitated the transition of the cubic structure.
Time-dependent magnetoelectric effect in Fe/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 heterostructure: A ferromagnetic resonance study
Authors: Zhao Yue-Lei , Chen Qian-Ping , Zhao Yong-Gang , Pan Liqing , Sun Young
Published: August 2013

Ferromagnetic resonance with applied electric fields has been used to investigate the magnetoelectric effect in a Fe/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 heterostructure. The out-of-plane magnetoelectric effect follows a butterfly behavior in response to electric field, consistent with the linear piezoelectric strain-mediated mechanism. In contrast, the in-plane magnetoelectric effect exhibits a loop-like dependence on electric field. In addition, a relaxation of the in-plane resonant field has been observed after the ferroelectric domains are switched. The loop-like feature and the time-dependent response suggest that the in-plane magnetoelectric coupling involves the 109° switching and relaxation of ferroelectric domains.
Fatigue mechanism of textured Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramics
Authors: Yan Yongke , Zhou Yuan , Gupta Shashaank , Priya Shashank
Published: August 2013

Grain orientation, BaTiO3 heterogeneous template content, and electrode materials are expected to play an important role in controlling the polarization fatigue behavior of ⟨001⟩ textured Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramics. A comparative analysis with randomly oriented ceramics showed that ⟨001⟩ grain orientation/texture exhibits improved fatigue characteristics due to the reduced switching activation energy and high domain mobility. The hypothesis was validated from the systematic characterization of polarization—electric field behavior and domain wall density. The defect accumulation at the grain boundary and clamping effect arising from the presence of BaTiO3 heterogeneous template in the final microstructure was found to be the main cause for polarization degradation in textured ceramic.
Atomic-scale structure, cation distribution, and bandgap bowing in Cu(In,Ga)S2 and Cu(In,Ga)Se2
Authors: Eckner S. , Kämmer H. , Steinbach T. , Gnauck M. , Johannes A. , Stephan C. , Schorr S. , Schnohr C. S.
Published: August 2013

Mixed chalcopyrite semiconductors like Cu(In,Ga)S2 and Cu(In,Ga)Se2 are characterized by the coexistence of different local atomic arrangements around the S or Se anion. The resulting anion displacement strongly influences the material bandgap. We studied the atomic-scale structure of Cu(In,Ga)S2 as a function of composition using x-ray absorption spectroscopy and valence force field simulations. Applying a specially developed model for not fully random cation distributions, we find that structural relaxation of the anion with respect to In and Ga contributes significantly more to the bandgap bowing observed for Cu(In,Ga)S2 and Cu(In,Ga)Se2 than relaxation with respect to Cu and group-III atoms.
Spectroscopy of self-assembled one-dimensional atomic string: The role of step edge
Authors: Cao Rongxing , Zhong Zhangfeng , Hu Jian , Zhang Xiaopu , Miao Bingfeng , Sun Liang , You Biao , Wu Di , Hu An , Zhang Weiyi , Ding Haifeng
Published: August 2013

Step-edge guided Gd one-dimensional atomic strings on Ag(111) surface are studied by scanning tunneling microscopy and spectroscopy at low temperature. Spectroscopy measurements show a characteristic peak, 65 meV above Fermi level in sharp contrast with tight-binding calculations of a string on a flat terrace. Good agreement can be obtained when the step edges are included in the calculations, revealing their roles on the electronic spectra of the self-assembled strings guided by step edges. The results are further confirmed by the spectroscopy study of Fe strings on a flat terrace and near step edges constructed by atomic manipulation.
Radially polarized tip-enhanced near-field coherent anti-Stokes Raman scattering microscopy for vibrational nano-imaging
Authors: Lin Jian , Zi Jian Er Kenneth , Zheng Wei , Huang Zhiwei
Published: August 2013

We report a radially polarized tip-enhanced near-field coherent anti-Stokes Raman scattering (RP-TE-CARS) microscopy technique for high-contrast vibrational imaging of subcellular organelles at nano-scale resolutions. The radially polarized pump and Stokes laser beams are tightly focused onto the sample while a gold-coated metallic probe is placed at the upper surface of the sample to enhance the electric field and CARS signals. The back-scattered CARS signal is measured with the gold-coated nano-tip being stationary at the focal region of laser beams. The RP-TE-CARS signal is ∼6-fold higher than that using linearly polarized laser excitation. We demonstrate the good performance of the RP-TE-CARS technique developed by imaging sub-micron polystyrene beads and mitochondria at nano-scale resolutions.
Theoretical comparison of Si, Ge, and GaAs ultrathin p-type double-gate metal oxide semiconductor transistors
Authors: Dib Elias , Bescond Marc , Cavassilas Nicolas , Michelini Fabienne , Raymond Laurent , Lannoo Michel
Published: August 2013

Based on a self-consistent multi-band quantum transport code including hole-phonon scattering, we compare current characteristics of Si, Ge, and GaAs p-type double-gate transistors. Electronic properties are analyzed as a function of (i) transport orientation, (ii) channel material, and (iii) gate length. We first show that ⟨100⟩-oriented devices offer better characteristics than their ⟨110⟩-counterparts independently of the material choice. Our results also point out that the weaker impact of scattering in Ge produces better electrical performances in long devices, while the moderate tunneling effect makes Si more advantageous in ultimately scaled transistors. Moreover, GaAs-based devices are less advantageous for shorter lengths and do not offer a high enough ON current for longer gate lengths. According to our simulations, the performance switching between Si and Ge occurs for a gate length of 12 nm. The conclusions of the study invite then to consider ⟨100⟩-oriented double-gate devices with Si for gate length shorter than 12 nm and Ge otherwise.
Influence of the gas-flow Reynolds number on a plasma column in a glass tube
Authors: Jin Dong Jun , Uhm Han S. , Cho Guangsup
Published: August 2013

Atmospheric-plasma generation inside a glass tube is influenced by gas stream behavior as described by the Reynolds number (Rn). In experiments with He, Ne, and Ar, the plasma column length increases with an increase in the gas flow rate under laminar flow characterized by Rn < 2000. The length of the plasma column decreases as the flow rate increases in the transition region of 2000 < Rn < 4000. For a turbulent flow beyond Rn > 4000, the length of the plasma column is short in front of the electrode, eventually leading to a shutdown.
Formation of low resistance ohmic contacts in GaN-based high electron mobility transistors with BCl3 surface plasma treatment
Authors: Fujishima Tatsuya , Joglekar Sameer , Piedra Daniel , Lee Hyung-Seok , Zhang Yuhao , Uedono Akira , Palacios Tomás
Published: August 2013

A BCl3 surface plasma treatment technique to reduce the resistance and to increase the uniformity of ohmic contacts in AlGaN/GaN high electron mobility transistors with a GaN cap layer has been established. This BCl3 plasma treatment was performed by an inductively coupled plasma reactive ion etching system under conditions that prevented any recess etching. The average contact resistances without plasma treatment, with SiCl4, and with BCl3 plasma treatment were 0.34, 0.41, and 0.17 Ω mm, respectively. Also, the standard deviation of the ohmic contact resistance with BCl3 plasma treatment was decreased. This decrease in the standard deviation of contact resistance can be explained by analyzing the surface condition of GaN with x-ray photoelectron spectroscopy and positron annihilation spectroscopy. We found that the proposed BCl3 plasma treatment technique can not only remove surface oxide but also introduce surface donor states that contribute to lower the ohmic contact resistance.
Assembly of thermally reduced graphene oxide nanostructures by alternating current dielectrophoresis as hydrogen-gas sensors
Authors: Wang Jianwei , Singh Budhi , Maeng Sunglyul , Joh Han-Ik , Kim Gil-Ho
Published: August 2013

Chemo-resistive hydrogen-gas sensors based on thermally reduced graphene oxide (rGO) have been fabricated on a micro-hotplate by positive ac dielectrophoresis (DEP). The optimized DEP parameters for manipulating rGO nanostructures into Au electrodes for hydrogen sensing are: applied frequency = 1 MHz, peak-to-peak voltage = 5 V, and DEP time = 30 s. The device exhibits good sensitivity (∼6%) with fast response time (∼11 s) and recovery time (∼36 s) for 200 ppm hydrogen gas at room temperature. This result indicates that the DEP process has great potential for assembling rGO for hydrogen-gas sensor in many industrial and scientific applications.
Silicon nanowire network metal-semiconductor-metal photodetectors
Authors: Mulazimoglu Emre , Coskun Sahin , Gunoven Mete , Butun Bayram , Ozbay Ekmel , Turan Rasit , Unalan Husnu Emrah
Published: August 2013

We report on the fabrication and characterization of solution-processed, highly flexible, silicon nanowire network based metal-semiconductor-metal photodetectors. Both the active part of the device and the electrodes are made of nanowire networks that provide both flexibility and transparency. Fabricated photodetectors showed a fast dynamic response, 0.43 ms for the rise and 0.58 ms for the fall-time, with a decent on/off ratio of 20. The effect of nanowire-density on transmittance and light on/off behavior were both investigated. Flexible photodetectors, on the other hand, were fabricated on polyethyleneterephthalate substrates and showed similar photodetector characteristics upon bending down to a radius of 1 cm.
Probing cell biophysical behavior based on actin cytoskeleton modeling and stretching manipulation with optical tweezers
Authors: Wang Kaiqun , Cheng Jinping , Han Cheng Shuk , Sun Dong
Published: August 2013

This letter presents an approach to utilizing the actin cytoskeleton model and optical tweezers technology to probe the distinct underlying F-actin remodeling mechanism and showing quantitatively how cell mechanical behavior is associated with alterations in the cell functions. The structural parameters of F-actin were extracted by fitting the modeling results with the experimental results obtained by cell stretching manipulation. Alterations of cell mechanical behaviors under distinct diseased cellular stages were further interpreted. Jurkat and K562 cells were used as sample cells. This letter successfully illustrates the correlation of the cell mechanical behavior and cell functional alterations in a quantitative way.
Surface polar optical phonon scattering of carriers in graphene on various substrates
Authors: Lin I-Tan , Liu Jia-Ming
Published: August 2013

The surface polar optical phonon scattering of carriers in graphene on various substrates is thoroughly studied using Rode's iteration method. The dependence of the scattering rate on carrier energy, temperature, and Fermi energy is investigated. The experimental data in the literature on the temperature dependence of the resistivity can be fitted using only one free fitting parameter. The fitting results show that the coupling strengths of surface optical phonons are much stronger, by at least a factor of 3.5, than the theoretical prediction. The strong coupling also suggests that the deformation potential of acoustic phonons might have been overestimated in the literature.
Modulation of the optical transmittance in multilayer graphene by an electrical signal
Authors: Benítez J. L. , Mendoza D.
Published: August 2013

The modulation of the optical transmittance in multilayer graphene by means of an electrical signal in the simple configuration of coplanar electrodes is reported. Besides the fundamental frequency of modulation, higher harmonics also appear in the transmitted signal. Modulation in the optical reflectance is also observed. The modulation of the optical properties in multilayer graphene by electrical signals may be useful for the transmission of information by optical means.
Enhanced dielectric and ferroelectric characteristics in Ca-modified BaTiO3 ceramics
Authors: Zhu Xiao Na , Zhang Wei , Chen Xiang Ming
Published: August 2013

Synergic modification of BaTiO3 ceramics was investigated by Ca-substitution, and the superior dielectric and ferroelectric properties were determined together with the structure evolution. X-ray diffraction (XRD) analysis demonstrated a large solubility limit above x = 0.25 in Ba1−xCaxTiO3 solid solution where the fine grain structure was observed with increasing x. Room temperature dielectric constant as high as 1655 was achieved in the present ceramics together with the significantly reduced dielectric loss of 0.013 (x = 0.20 at 100 kHz), where the Curie temperature kept almost a constant while other two transition temperatures decreased continuously with increasing x. More importantly, the remanent polarization Pr and dielectric strength Eb were significantly enhanced by Ca-substitution, and the best Pr (11.34 μC/cm2) and the highest dielectric strength Eb (75 kV/cm) were acquired at x = 0.25. The present ceramics should be very desirable for the applications such as high density energy storage devices.
Enhanced phase and charge diffusion due to radio-frequency/microwave excitation in Bloch transistors
Authors: Liou Saxon , Kuo Watson
Published: August 2013

Current-voltage characteristics and switching current of Bloch transistors under radio-frequency/microwave excitations were experimental studied, respectively revealing pronounced summational superconducting phase diffusion and central-island charge diffusion. The phase diffusion, which can be quantified by the zero-bias resistance, was found minimal when two charge states in the transistor are degenerate. The switching current, which also reflects the charge diffusion, was observed that becomes minimal at the degeneracy beyond a threshold in ac driving power. The charge diffusion was analyzed using an electric dipolar interaction between the photon field and excess charge on the central island.
Engineering the Design of Brightly-Emitting Luminescent Nanostructured Photonic Composite Systems
Authors: Tan Mei Chee , Naczynski Dominik J. , Moghe Prabhas V. , Riman Richard E.
Published: August 2013

Rare-earth doped infrared emitting composites have extensive applications in integrated optical devices such as fibre amplifiers and waveguides for telecommunications, remote sensing, and optoelectronics. In addition, recent advancements in infrared optical imaging systems have expanded the biomedical applications for infrared-emitting composites in diagnosis and imaging of living tissue systems both in vitro and in vivo. Composite systems combine the advantages of polymers (light weight, flexibility, good impact resistance, improved biomedical compatibility, and excellent processability) and inorganic phosphor host materials (low phonon energy, intense emissions, chemical durability, and high thermal stability). This paper provides a brief review of our research progress in the design and synthesis of luminescent photonic nanocomposite systems comprised of rare-earth doped particulates dispersed in a continuous polymeric matrix. The design of brightly-emitting rare-earth doped materials and the influence of host and dopant chemistries on the emission properties are discussed. Methods used to assess and measure the phosphors’ performance are also evaluated in this work. This paper will also examine the solvothermal synthesis method used to control the physical and chemical characteristics of the rare-earth doped particles, and how these characteristics impact the infrared optical properties. Also presented here are recent advances reported with luminescent nanocomposite systems fabricated for optical waveguides and biomedical imaging.
Development of Inhibitors of Plasmodium falciparum Apical Membrane Antigen 1 Based on Fragment Screening
Authors: Lim San Sui , Debono Cael O. , MacRaild Christopher A. , Chandrashekaran Indu R. , Dolezal Olan , Anders Robin F. , Simpson Jamie S. , Scanlon Martin J. , Devine Shane M. , Scammells Peter J. , Norton Raymond S.
Published: August 2013

Apical membrane antigen 1 (AMA1) is an essential component of the moving junction complex used by Plasmodium falciparum to invade human red blood cells. AMA1 has a conserved hydrophobic cleft that is the site of key interactions with the rhoptry neck protein complex. Our goal is to develop small molecule inhibitors of AMA1 with broad strain specificity, which we are pursuing using a fragment-based approach. In our screening campaign, we identified fragments that bind to the hydrophobic cleft with a hit rate of 5 %. The high hit rate observed strongly suggests that a druggable pocket is present within the cleft.
Total Synthesis of Bouchardatine
Authors: Naik Nilesh H. , Urmode Tukaram D. , Sikder Arun K. , Kusurkar Radhika S.
Published: August 2013

Two new, efficient and simple routes using Heck-type reaction and intramolecular cyclization were developed for the synthesis of the naturally occurring cytotoxic alkaloid 2-(4-oxo-3,4-dihydroquinazolin-2-yl)-1H-indole-3-carbaldehyde (bouchardatine).
Neuropsychological Functioning among Chronic Khat Users in Jazan Region, Saudi Arabia
Authors: Ismail Ahmed A. , El Sanosy Rashad M. , Rohlman Diane S. , El-Setouhy Maged
Published: August 2013

Background

Khat chewing effects in the central nervous system are attributed to cathinone and cathine, which are structurally related to amphetamine. However, studies on neuropsychological problems arising from khat use in humans are not extensive and have only included observational and single-case studies. The aims of this study were to (1) to examine neuropsychological functions among khat chewers, and (2) to determine factors affecting neuropsychological outcomes among khat chewers.

Methods

A sample of 70 adult male khat chewers and a control group of 72 nonchewers were recruited from the Jazan region in southwest Saudi Arabia. A questionnaire examining socioeconomic background, medical and occupational history, education, and khat chewing behaviors was administered. Neuropsychological performance was assessed using computerized tests from the Behavioral Assessment and Research System (BARS) that assessed learning, episodic and working memory, motor speed/coordination, attention/information processing speed, sustained attention, set-shifting/response inhibition, and perceptual functions; noncomputerized tests, Trail Making A and B, Block Design, and Benton Visual Retention tests were also administered.

Results

Khat chewers performed significantly worse on 3 out of 14 neuropsychological subtests compared with the control group, representing learning, motor speed/coordination, and set-shifting/response inhibition functions. Age and educational level were identified as predictors of neuropsychological outcomes of khat chewers.

Conclusions

The chronic chewing of khat leaves is associated with deficits in some neuropsychological functions, which may affect the mental and neurological health of communities in which khat chewing is a common habit.
Endocarditis due to a co-infection of Candida albicans and Candida tropicalis in a drug abuser
Authors: Fesharaki Shirinsadat Hashemi , Haghani Iman , Mousavi Bita , Kargar Melika Laal , Boroumand Mohammadali , Anvari Maryam Sotoudeh , Abbasi Kyomars , Meis Jacques F. , Badali Hamid
Published: August 2013

In recent decades the incidence of Candida endocarditis has increased dramatically. Despite the application of surgery and antifungal therapy, Candida endocarditis remains a life-threatening infection with significant morbidity and mortality. We report a 37-year-old male drug abuser presenting with high fever, chest pain, loss of appetite and cardiac failure. His echocardiography revealed mobile large tricuspid valve vegetations. Fungal endocarditis was confirmed by culturing of the resected vegetation showing mixed growth of Candida albicans and Candida tropicalis, although three consecutive blood cultures were negative for Candida species. Phenotypic identification was reconfirmed by sequencing of the internal transcribed spacer (ITS rDNA) region. The patient was initially treated with intravenous fluconazole (6 mg kg−1 per day), followed by 2 weeks of intravenous amphotericin B deoxycholate (1 mg kg−1 per day). Although MICs were low for both drugs, the patient’s antifungal therapy combined with valve replacement failed, and he died due to respiratory failure.
Mutagenesis of Individual Pentatricopeptide Repeat Motifs Affects RNA Binding Activity and Reveals Functional Partitioning of Arabidopsis PROTON GRADIENT REGULATION3
Authors: Fujii Sota , Sato Nozomi , Shikanai Toshiharu
Published: August 2013

Pentatricopeptide repeat (PPR) proteins bind RNA and act in multiple eukaryotic processes, including RNA editing, RNA stability, and translation. Here, we investigated the mechanism underlying the functional versatility of Arabidopsis thaliana PROTON GRADIENT REGULATION3 (PGR3), a chloroplast protein harboring 27 PPR motifs. Previous studies suggested that PGR3 acts in (1) stabilization of photosynthetic electron transport L (petL) operon RNA, (2) translation of petL, and (3) translation of ndhA. We showed here that replacement of the 4th amino acid of the 12th PPR with nonpolar or charged amino acids abolished functions (1) and (2) but not (3) of PGR3 by compromising the function of this specific PPR. This discovery enabled us to knock out the RNA binding ability of individual PPR motifs. Consequently, we showed that the 16 N-terminal PPRs were sufficient for function (1) via sequence-specific RNA binding, whereas the 11 C-terminal motifs were essential for functions (2) and (3) by activating translation. We also clarified that the 14th amino acid of the 12th PPR should be positively charged to make the PPR functionally active. Our finding opens up the possibility of selectively manipulating the functions of PPR proteins.
3D diffraction imaging of linear features and its application to seismic monitoring
Authors: Alonaizi Faisal , Pevzner Roman , Bóna Andrej , Shulakova Valeriya , Gurevich Boris
Published: August 2013

Many subsurface features, such as faults, fractures, cracks, or fluid content terminations are defined by geological discontinuities. The seismic response from such features is encoded in diffractions. We develop an algorithm for imaging such discontinuities by detecting edge diffractions. The algorithm exploits phase‐reversal phenomena of edge diffractions and uses them as a criterion to separate these diffractions from specular reflections and diffractions produced by a leaner object. The performance of the method is demonstrated on both synthetic and real 3D seismic data. The output image focuses the diffracted energy back to its origin and shows high semblance values at the edge of the object. The method is applied on conventionally stacked data producing an image that contains only diffraction events called the D‐volume. We also reveal the potential of diffractions to image and track the changes of a CO2 plume using time‐lapse analysis and detect any possible CO2 seepage from its primary containment.
Rhythm and Noise: The City, Memory and the Archive
Authors: Hetherington Kevin
Published: August 2013

Henri Lefebvre's Rhythmanalysis, while typically loose and underdeveloped as a work, offers a highly suggestive way of thinking about mobility and pattern within spatiality, and also alerts our attention to the importance of temporal rhythms. This paper is concerned with the rhythms of history within the city, notably how heritage gets made, remade and unmade within the city as a form of archive. Comparing Lefebvre's concept of rhythm to that of noise in Michel Serres (notably in his book Genesis), I explore the meaning of urban heritage – in which the past is made present – analysing how the past can interrupt the present within the city and how that opens up possibilities for critical reception and potential alternative urban futures.
Points of Departure: Listening to Rhythm in the Sonoric Spaces of the Railway Station
Authors: Revill George
Published: August 2013

This paper argues that rather than simply enabling studies of regulation and embodiment, rhythm can facilitate reintegration of the apparently separate dimensions of mobile experience enabling them, as Cresswell says, to ‘make sense together’. Taking a critical lead from Lefebvre's engagement with Lacan, it argues that in order for this to happen a more active and reflexive sense of listening to rhythm is needed than that provided by Lefebvre. Drawing on a conception of listening developed by Ihde, Nancy and LaBelle the paper concludes by exploring some ways in which the rhythms of the railway station produce experiences which are simultaneously affectively embodied and deeply socially and culturally meaningful.
Communicating the Rhythms of Retromodernity: ‘Confused and Mixed Shanghai’
Authors: Lagerkvist Amanda
Published: August 2013

Visitors on sight-seeing tours in contemporary globalizing Shanghai observe the futuristic ambitions, exponential development and chaotic polyrhythmicity of New Shanghai. The nostalgia industry simultaneously ‘teleports’ the tourists on tours back to a time when Shanghai was a legendary world metropolis; the Golden Age of the inter-war era. Inspired by Henri Lefebvre's critical rhythmanalysis, and by Jonathan Sterne's conceptualization of communication as organized movement and action, this paper explores bus tours by commission of the municipal government. Shanghai is the place where the movements of the buses, as well as the tourists on board, become part of communicating the place identity and multiple rhythms of the city. The buses are conceived as means of communication, in a twofold sense, and as both underscoring and binding together the many incommensurabilities of place: old and new, Western and Chinese, industrialism and post-industrialism, nationalism and globalism. The author argues that mobility, media modernity and a confounding mixture (reflexively manifested on the tour ‘Confused and Mixed Shanghai’) constitute a collective memory of the city, and that the buses in all their seeming banality, communicate Shanghai's particular rhythms of retromodernity.
Polycarp's Cup: Imitatio in the Martyrdom of Polycarp
Authors: Cobb L. Stephanie
Published: August 2013

While imitatio Christi has widely been recognised as a narrative element of the Martyrdom of Polycarp, other possible literary allusions have been under‐explored. This article examines the presence of allusions to the death of Socrates in the Martyrdom of Polycarp. Socrates was often used in Christian apologetic contexts, thus its possible presence in Martyrdom of Polycarp is not surprising. This article seeks to understand the narrative function of Socratic allusions, especially relating to the text's construction of martyrdom and its Christology. It posits that imitatio Christi and imitatio Socratis function together apologetically to demonstrate the reasonableness of Christian worship of Jesus.