In order to investigate the origin of multiple populations in globular clusters (GCs), we have constructed new chemical evolution models for proto-GCs where the supernova blast waves undergo blowout without expelling the ambient gas. Chemical enrichments in our models are then dictated by the winds of massive stars together with the asymptotic-giant-branch stars ejecta. We find that the observed Na-O anti-correlation can be reproduced when multiple episodes of starburst and enrichment are allowed to continue in proto-GCs. The “mass budget problem” is mostly resolved by our models without ad-hoc assumptions on star formation efficiency, initial mass function, and significant loss of first-generation stars. Interestingly, ages and chemical abundances predicted by this chemical evolution model are in good agreements with those independently obtained from our stellar evolution model for the horizontal-branch. We also discuss observational evidence for the GC-like multiple populations in the Milky Way bulge.

Recent extensive nanomechanical experiments have revealed that the instantaneous strength and plasticity of a material can be significantly affected by the size (of sample, microstructure, or stressed zone). One more important property to be added into the list of size-dependent properties is time-dependent plastic deformation referred to as creep; it has been reported that the creep becomes more active at the small scale. Analyzing the creep in the small scale can be valuable not only for solving scientific curiosity but also for obtaining practical engineering information about the lifetime or durability of advanced small-scale structures. For the purpose, nanoindentation creep experiments have been widely performed by far. Here we critically review the existing nanoindentation creep methods and the related issues and finally suggest possible novel ways to better estimate the small-scale creep properties.

We investigate the empirical relation between corporate governance and stock market liquidity. We find that firms with better corporate governance have narrower spreads, higher market quality index, smaller price impact of trades, and lower probability of information-based trading. In addition, we show that changes in our liquidity measures are significantly related to changes in the governance index over time. These results suggest that firms may alleviate information-based trading and improve stock market liquidity by adopting corporate governance standards that mitigate informational asymmetries. Our results are remarkably robust to alternative model specifications, across exchanges, and to different measures of liquidity.

We report the discovery of three new star clusters in the halo of the Local Group dwarf irregular galaxy NGC 6822. These clusters were found in the deep images taken with the MegaPrime at the CFHT covering a total field of 2 deg $\times$ 2 deg. The most remote cluster is found to be located as far as 79 arcmin away from the center of NGC 6822. This distance is several times larger than the size of the region in NGC 6822 where star clusters were previously found. Morphological structures of the clusters and color-magnitude diagrams of the resolved stars in the clusters show that at least two of these clusters are proabably old globular clusters.

This paper reports an unusual case in which aseptic meningitis presented with sudden sensorineural hearing loss (SSNHL) associated with intralabyrinthine haemorrhage (ILH). A seven-year-old girl presented with sudden right-sided hearing loss with dizziness. She did not have a previous history of bleeding disorders. This child was assessed using audiograms and magnetic resonance imaging (MRI). The patient's hearing loss was irreversible. Steroid therapy was not effective. SSNHL associated with ILH can be one of the negative prognostic factors in children.

AlxGa1-xN sample with x=0.36 was epitaxially grown on sapphire by MOCVD. SAW velocity of 5420 m/s and TCF (temperature coefficient of frequency) of -51.20 ppm/°C were measured from the SAW devices fabricated on the AlxGa1-xN sample, when kh value was 0.078, at temperatures between –30 °C and 60 °C Electromechanical coupling coefficient was ranged from 1.26 % to 2.22 %. The fabricated SAW filter have shown a good device performance with insertion loss of -33.853 dB and side lobe attenuation of 20 dB.

We have studied the effect of ion doping on the electrical properties for atmospheric pressute chemical vapor deposition (APCVD) amorphous silicon (a-Si) films. The room temperature conductivities after ion doping at optimurr doping tenperatures for n− and p-type a-Si films were found to be > 10−2 and >10−4 S/cm, respectively. The unintentional hydrogen incorporation into a-Si during ion doping enhances the quality of ion doped APCVD a-Si as compared to that of plasma enhanced CVD (PECVD) a-Si:H. We obtained the field effect mobility of > 1 cm2/Vs for APCVD a-Si TFT using ion doped n+-layer.

We have studied the effect of ion doping on the electrical properties for atmospheric pressure chemical vapor deposition (APCVD) Amorphous silicon (a-Si) films. The room temperature conductivities after ion doping at optimum doping temperatures for n- and p-type a-Si films were found to be > 10−2 and > 10−4 S/cm, respectively. The unintentional hydrogen incorporation into a-Si during ion doping enhances the quality of ion doped APCVD a-Si as compared to that of plasma enhanced CVD (PECVD) a-S.i.H. We obtained the field effect mobility of > 1 cm2/Vs for APCVD a-Si TFT using ion doped n+-layer.

We have studied the effect of O2 plasma exposure on the performance of polycrystalline silicon (poly-Si) thin film transistor (TFTs). The field effect mobility is increased and the drain currents at negative gate voltages are reduced by O2 plasma exposure on the surface of the TFT. These improvements in the performance of the poly-Si TFTs are larger in offset structure compared to overlap one. We obtained the on/off current ratio of ∼ 108 after O2 plasma exposure for the poly-Si TFTs with 3 or 4 μm offset length.

The hydrogenation effect was studied in the fabrication of amorphous silicon thin film transistor using APCVD technique. The inverse staggered type a-Si TFTs were fabricated with the deposited a-Si and SiO2 films by the atmospheric pressure (AP) CVD. The field effect mobility of the fabricated a-Si TFT is 0.79 cm2/Vs and threshold voltage is 5.4V after post hydrogenation. These results can be applied to make low cost a-Si TFT array using an in-line APCVD system.

We have studied the depositions of amorphous silicon, silicon carbon alloy, doped microcrystalline silicon in order to apply these films as the component materials for the p-i-n and double stacked solar cells. We have obtained low band gap a-Si:H by decreasing the deposition rate under the proper preparation conditions and highly conductive, thin microcrystalline Si and SiC layers. We have developed a stable a-Si/a-Si double stacked solar cell with a conversion efficiency of ∼ % using narrow band gap a-Si:H as a i-layer of bottom cell.The performance of this cell does not degrade until 100 hrs illumination under 350 mW/cm2.

We have studied the preparation and device application of a-Si by atmospheric pressure CVD using disilane. The deposition rate of a-Si increases with the partial pressure of disilane and with the total pressure. The deposition rate of APCVD a-Si is, therefore, very high compared with LPCVD. The photosensitivity of APCVD a-Si is 104 at 100mW/cm2. We have made an inverse staggered type a-Si TFT using SiO2 as a gate insulator. The on/off current ratio and field effect mobility are 105 and 0.19cm2/Vs, respectively.

We have studied the effect of RF power on the properties of Si thin films prepared by a conventional plasma and remote plasma(RP)- CVD. The structure of the Si film changes from amorphous to crystalline with increasing RF power in RP-CVD. However, the structure of Si film deposited by P-CVD remains amorphous with increasing RF power. The relaxation of Si atoms by means of chemical annealing of He metastable atoms gives rise to the formation of macrocrystalline structure at the high RF powers.

We studied the growth of polycrystalline silicon by using remote plasma chemical vapour deposition technique. The effects of RF power and the substrate temperature on the structural properties have been investigated. With increasing the RF power, the crystalline volume fraction and the grain size increase up to 100W, but decrease for the further increase in power level. We obtained the poly-Si with the crystalline volume fraction of about 74 at.% at the substrate temperature of 330°C.

We studied the layer by layer deposition technique of a-Si:H film, where the hydrogen radicals are exposed between the deposition of each layer. The effects of each layer thickness and hydrogen radical exposure time on the electrical and optical properties were studied. With the decrease of the each layer thickness, more hydrogen is involved in the network if the structure is still amorphous, but the hydrogen content is very small for microcrystal Si formed by long exposure to hydrogen radicals in between the depositions of thin layers.

We have studied the improvement of the quality of undoped a-Si:H deposited by remote-plasma chemical vapour deposition. The effects of reactant gas concentration, rf power, substrate bias voltage on the electrical and optical properties have been investigated. Some hydrogen dilution of si lane improves the photoeletric property and a high rf power gives rise to the defect creation due to the ion bombardment on the growing surface. The positive substrate bias improves the quality of undoped a-Si:H.