All-Optical Ultrafast Control and Read-Out of a Single Negatively Charged Self-Assembled InAs Quantum Dot

We demonstrate the all-optical ultrafast manipulation and read-out of optical transitions in a single negatively charged self-assembled InAs quantum dot, an important step towards ultrafast control of the resident spin. Experiments performed at zero magnetic field show the excitation and decay of the trion (negatively charged exciton) as well as Rabi oscillations between the electron and trion states. Application of a DC magnetic field perpendicular to the growth axis of the dot enables observation of a complex quantum beat structure produced by independent precession of the ground state electron and the excited state heavy hole spins

Improved hydrogen-sensitive properties of MISiC Schottky sensor with thin NO-grown oxynitride as gate insulator

Thin oxynitride grown in NO at low temperature was successfully used as gate insulator for fabricating MISiC Schottky hydrogen sensors. Response properties of the sensors were compared with other MISiC Schottky sensors with thicker or no oxynitride. It was found that the thin oxynitride played an important role in increasing device sensitivity and stability. Even at a low H 2 concentration, e.g., 100-ppm H 2 in N 2, a significant response was observed, indicating a promising application for detecting hydrogen leakage. Moreover, a rapid and stable dynamic response on the introduction and removal of H 2/N 2 mixed gas was realized for the sensor. Improved interface properties and larger barrier height associated with the thin oxynitride are responsible for the excellent response characteristics. As a result, NO oxidation could be a superior process for preparing highly sensitive and highly reliable MISiC Schottky hydrogen sensors.published_or_final_versio

Electromagnetic optimal design of a linear induction motor in linear metro

An improved T-model equivalent circuit of a single-sided linear induction machine (SLIM) is proposed. The analysis utilizes a set of one-dimensional air gap flux linkage equations. The model takes longitudinal end and transversal edge effects into consideration. These have to account for primary terminal half-filled slots, secondary back-iron saturation and skin effect in the secondary conducting sheet. In the circuit, several coefficients are obtained by use of the dummy electric potential method in conjunction with consideration of the complex power equivalence between the primary and secondary sides. The coefficients derived include the longitudinal end effect coefficients K r and Kx, transversal edge effect coefficients C r and Cx, and skin effect coefficient Kf. The accuracy of the T-model is validated using comparison to a set of measured data under constant current - constant frequency conditions. These were taken from the Intermediate Capacity Transit System (ICTS) in Canada. An optimal design scheme for the SLIM is addressed. The application used for the optimization is a prototype propulsion system in a high temperature superconducting (HTS) maglev drive. The efficiency and primary weight are chosen as optimal objective functions while the thrust, power factor and other performance indexes are calculated. © 2010 IEEE

Stress and its effect on optical properties of GaN epilayers grown on Si(111), 6H-SiC(0001), and c-plane sapphire

Stress and its effects on optical properties of GaN epilayers grown in Si(111), 6H-SiC(0001), and c-plane sapphire were investigated. Large tensile stress was present in GaN epilayers grown on Si and 6H-SiC, and a small compressive stress appeared in the film grown on sapphire. The results showed that the thermal mismatch between the epilayers and the substrates plays a major role in determining the residual strain in the films.published_or_final_versio

TIFA, an inflammatory signaling adaptor, is tumor suppressive for liver cancer.

TIFA (TNF receptor associated factor (TRAF)-interacting protein with a Forkhead-associated (FHA) domain), also called T2BP, was first identified using a yeast two-hybrid screening. TIFA contains a FHA domain, which directly binds phosphothreonine and phosphoserine, and a consensus TRAF6-binding motif. TIFA-mediated oligomerization and poly-ubiquitinylation of TRAF6 mediates signaling downstream of the Tumor necrosis factor alpha receptor 1 (TNFaR-I) and interleukin-1/Toll-like receptor 4 (TLR4) pathways. Examining TIFA expression in hepatocellular carcinoma (HCC) tissues microarrays, we noted marked decreases TIFA reactivity in tumor versus control samples. In agreement, we found that HCC cell lines show reduced TIFA expression levels versus normal liver controls. Reconstituting TIFA expression in HCC cell lines promoted two independent apoptosis signaling pathways: the induction of p53 and cell cycle arrest, and the activation of caspase-8 and caspase-3. In contrast, the expression of a non-oligomerizing mutant of TIFA impacted cells minimally, and suppression of TIFA expression protected cells from apoptosis. Mice bearing TIFA overexpression hepatocellular xenografts develop smaller tumors versus TIFA mutant tumors; terminal deoxynucleotidyl transferase dUTP nick end labeling staining demonstrates increased cell apoptosis, and decreased proliferation, reflecting cell cycle arrest. Interestingly, p53 has a greater role in decreased proliferation than cell death, as it appeared dispensable for TIFA-induced cell killing. The findings demonstrate a novel suppressive role of TIFA in HCC progression via promotion of cell death independent of p53

The genus Philoctetes Abeille de Perrin, 1879 from China, with description of two new species (Hymenoptera, Chrysididae)

Copyright © 2015 Magnolia Press. Licensed under a Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0. This is the published version of the article.NHM Repositor

An improved series equivalent circuit of a single-sided linear induction motor

The derivation of the equivalent circuit for a single-sided linear induction motor (SLIM) is not straightforward. Especially if it includes longitudinal end effects from the cut-open primary magnetic path, transverse edge effects from the differing widths between the primary lamination and secondary sheet, and half filled primary slots. This paper proposes an improved series equivalent circuit for this machine. The longitudinal end effects are estimated using three different impedances representing the normal, forwards and backwards flux density waves in the air-gap. The transverse edge effects accounted for with a correction coefficient Kt and an air-gap flux density correction coefficient Kb. Using the series circuit, the performance of the SLIM was assessed in a similar manner to a rotating induction machine. A 4 kW SLIM prototype was tested which validated the simulation technique ©2009 IEEE

Can interference patterns in the reflectance spectra of GaN epilayers give important information of carrier concentration?

Low-temperature reflectance spectra of a series of Si-doped GaN epilayers with different doping concentrations grown on sapphire by metal-organic chemical vapour deposition were measured. In addition to the excitonic polariton resonance structures at the band edge, interference oscillating patterns were observed in the energy region well below the band gap. The amplitudes of these oscillation patterns show a distinct dependence on the doping concentrations of the samples. From the thin-film optical interference principle, an approach connecting the amplitude of the interference oscillations and the impurity scattering was established. Good agreement between experiment and theory is achieved. © 2012 American Institute of Physics.published_or_final_versio

Hydroxy double salts loaded with bioactive ions: Synthesis, intercalation mechanisms, and functional performance

The intercalation of the anions of diclofenac (Dic), naproxen (Nap), and valproic acid (Val) into three hydroxy double salts (HDSs) has been explored in this work. Experiments were performed with [Co1.2Zn3.8(OH)8](NO3)2·2H2O (CoZn-NO3), [Ni2Zn3(OH)8](NO3)2·2H2O (NiZn-NO3) and [Zn5(OH)8](NO3)2·2H2O (Zn-NO3). It proved possible to intercalate diclofenac and naproxen into all three HDSs. In contrast, Val could be intercalated into CoZn-NO3 but when it was reacted with Zn-NO3 the HDS structure was destroyed, and the product comprised ZnO. Successful intercalation was verified by X-ray diffraction, IR spectroscopy, and elemental microanalysis. Molecular dynamics simulations showed the Dic and Nap ions to arrange themselves in an “X” shape in the interlayer space, forming a bilayer. Val was found to adopt a position with its aliphatic groups parallel to the HDS layer, again in a bilayer. In situ time resolved X-ray diffraction experiments revealed that intercalation of Dic and Nap into CoZn-NO3 and Zn-NO3 is mechanistically complex, with a number of intermediate phases observed. In contrast, the intercalation of all three guests into NiZn-NO3 and of Val into CoZn-NO3 are simple one step reactions proceeding directly from the starting material to the product. The HDS-drug composites were found to have sustained release profiles

Probing deep level centers in GaN epilayers with variable-frequency capacitance-voltage characteristics of AuGaN Schottky contacts

Under identical preparation conditions, AuGaN Schottky contacts were prepared on two kinds of GaN epilayers with significantly different background electron concentrations and mobility as well as yellow emission intensities. Current-voltage (I-V) and variable-frequency capacitance-voltage (C-V) characteristics show that the Schottky contacts on the GaN epilayer with a higher background carrier concentration and strong yellow emission exhibit anomalous reverse-bias I-V and C-V characteristics. This is attributed to the presence of deep level centers. Theoretical simulation of the low-frequency C-V curves leads to a determination of the density and energy level position of the deep centers. © 2006 American Institute of Physics.published_or_final_versio