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Astrophysically Important 26Si States Studied with the 28Si(4He,6He)26Si Reaction
Y. K. Kwon,이춘식,J. Y. Moon,J. H. Lee,J. Y. Kim,M. K. Cheoun,S. Kubono,H. Yamaguchi,J. J. He,A. Saito,Y. Wakabayashi,H. Fujikawa,G. Amadio,N. Iwasa,K. Inafuku,L. H. Khiem,M. Tanaka,Y. Fuchi,A. A. Chen,S 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2
The emission of a 1.809-MeV γ-ray from the first excited state of 26Mg, followed by β-decay of 26Al in its ground state (denoted as 26Alg.s.), has been identied by several gamma-ray telescopes. To resolve the controversy over the possible sources of the observational 1.809-MeV γ-rays, one needs accurate knowledge of the production rate of 26Alg.s.. The 25Al(p,γ)26Si reaction is one of the most important astrophysical reactions to be investigated, but its rate is uncertain due to the lack of level information on 26Si above the proton threshold (Qpγ = 5.518 MeV). Illiadis et al. suggested that the 25Al(p,γ)26Si reaction should be dominated by a 3+ unnatural parity state at Ex = 5970 keV. Recent studies proposed several states as candidates for the 3+ states. However, the spin-parity assignments for these states are still uncertain. In the present work, we measured the 28Si(4He,6He)26Si reaction at 120 MeV to confirm the unnatural parity states just above the proton threshold. The measurement was performed with the high-resolution particle analyzer at the Center for Nuclear Study, University of Tokyo. We observed a total of 22 excited states in 26Si. The 7018-keV level, which was only observed by Bardayan et al. with the 28Si(p; t)26Si reaction, was confirmed in our measurement. Among the candidates of unnatural parity states at Ex = 5678, 5916, and 5945 keV, the 5918-keV state was only observed within the error of the excitation energy. A new state at Ex = 6101 keV was also identified.
Field measurements of wind characteristics over hilly terrain within surface layer
He, Y.C.,Chan, P.W.,Li, Q.S. Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.19 No.5
This paper investigates the topographic effects on wind characteristics over hilly terrain, based on wind data recorded at a number of meteorological stations in or near complex terrain. The multiply data sources allow a more detailed investigation of the flow field than is normally possible. Vertical profiles of mean and turbulent wind components from a Sodar profiler were presented and then modeled as functions of height and wind speed. The correlations between longitudinal and vertical wind components were discussed. The phenomena of flow separation and generation of vortices were observed. The distance-dependence of the topographic effects on gust factors was revealed subsequently. Furthermore, the canyon effect was identified and discussed based on the observations of wind at a saddle point between two mountain peaks. This study aims to further understanding of the characteristics of surface wind over rugged terrain. The presented results are expected to be useful for structural design, prevention of pollutant dispersion, and validation of CFD (computational fluid dynamics) models or techniques over complex terrains.
Time domain identification of multiple cracks in a beam
He, Z.Y.,Lu, Z.R. Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.6
It is well known that the analytical vibration characteristic of a cracked beam depends largely on the crack model. In the forward analysis, an improved and simplified approach in modeling discrete open cracks in beams is presented. The effective length of the crack zone on both sides of a crack with stiffness reduction is formulated in terms of the crack depth. Both free and forced vibrations of cracked beams are studied in this paper and the results from the proposed modified crack model and other existing models are compared. The modified crack model gives very accurate predictions in the modal frequencies and time responses of the beams particularly with overlaps in the effective lengths with reduced stiffness. In the inverse analysis, the response sensitivity with respect to damage parameters (the location and depth of crack, etc.) is derived. And the dynamic response sensitivity is used to update the damage parameters. The identified results from both numerical simulations and experiment work illustrate the effectiveness of the proposed method.
He, D.,Zheng, C.,Wang, Q.,He, C.,Lee, Y.I.,Wu, L.,Hou, X. Pergamon Press ; Elsevier Science Ltd 2015 Talanta Vol.142 No.-
In this work, we proposed a dielectric barrier discharge (DBD)-assisted one-pot strategy to fabricate carbon quantum dots (CQDs) using only one reagent N, N-dimethylformamide (DMF) at atmospheric pressure and room temperature. The experimental conditions were carefully investigated, and the prepared CQDs were characterized by using UV-vis spectrophotometer, fluorescence spectrophotometer, Fourier transform infrared (FTIR) spectrometer, transmission electron microscopy (TEM) and X-ray photoelectron spectrometer (XPS). The CQDs have an average size of 3.6nm in diameter with narrow size distribution, and can be used as highly selective and sensitive fluorescence probes for hydrogen peroxide and glucose, with limits of detection of 3.8μM and 3.5μM, respectively.
He, X.,Bonaparte, N.,Kim, S.,Acharya, B.,Lee, J.Y.,Chi, L.,Lee, H.J.,Paik, Y.K.,Moon, P.G.,Baek, M.C.,Lee, E.K.,Kim, J.H.,Kim, I.S.,Lee, B.H. Elsevier Science Publishers 2012 Journal of controlled release Vol.162 No.3
Chemotherapy-induced apoptosis of tumor cells enhances the antigen presentation and sensitizes tumor cells to T cell-mediated cytotoxicity. Here we harnessed the apoptosis of tumor cells as a homing signal for the delivery of T cells to tumor. Jurkat T cells were anchored with ApoPep-1, an apoptosis-targeted peptide ligand, using the biocompatible anchor for membrane (BAM), an oleyl acid derivative. The ApoPep-1-BAM conjugate was efficiently anchored to cell membrane, while little anchoring was obtained with ApoPep-1 alone. The retention period of the ApoPep-1-BAM conjugate on cell membrane was approximately 80 and 40min in the absence and presence of serum, respectively. ApoPep-1 was resistant to degradation in serum until 2h. The apoptosis-targeted T cells that were anchored with the ApoPep-1-BAM preferentially bound to apoptotic tumor cells over living cells. When intravenously injected into tumor-bearing mice, the number of apoptosis-targeted T cells and in vivo fluorescence signals by the homing of the cells to doxorubicin-treated tumor were higher than those of untargeted T cells. Accumulation of apoptosis-targeted T cells at other organs such as liver was not detected. These results suggest that the chemotherapy-induced apoptosis and subsequent enhancement of T cell delivery to tumor by the membrane anchoring of the apoptosis-targeted peptide could be a novel strategy for cancer immunotherapy.
Wind profiles of tropical cyclones as observed by Doppler wind profiler and anemometer
He, Y.C.,Chan, P.W.,Li, Q.S. Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.17 No.4
This paper investigates the vertical profiles of horizontal mean wind speed and direction based on the synchronized measurements from a Doppler radar profiler and an anemometer during 16 tropical cyclones at a coastal site in Hong Kong. The speed profiles with both open sea and hilly exposures were found to follow the log-law below a height of 500 m. Above this height, there was an additional wind speed shear in the profile for hilly upwind terrain. The fitting parameters with both the power-law and the log-law varied with wind strength. The direction profiles were also sensitive to local terrain setups and surrounding topographic features. For a uniform open sea terrain, wind direction veered logarithmically with height from the surface level up to the free atmospheric altitude of about 1200 m. The accumulated veering angle within the whole boundary layer was observed to be $30^{\circ}$. Mean wind direction under other terrain conditions also increased logarithmically with height above 500 m with a trend of rougher exposures corresponding to lager veering angles. A number of empirical parameters for engineering applications were presented, including the speed adjustment factors, power exponents of speed profiles, and veering angle, etc. The objective of this study aims to provide useful information on boundary layer wind characteristics for wind-resistant design of high-rise structures in coastal areas.
He, W.,Van Ngoc, H.,Qian, Y.T.,Hwang, J.S.,Yan, Y.P.,Choi, H.,Kang, D.J. New York] ; North-Holland 2017 APPLIED SURFACE SCIENCE - Vol.392 No.-
We report that ultra-thin tellurium (Te) nanoflakes were successfully grown on a sample of a gold-coated textile, which then was used as an active piezoelectric material. An output voltage of 4V and a current of 300nA were obtained from the bending test under a driving frequency of 10Hz. To test the practical applications, Te nanoflake nanogenerator (TFNG) device was attached to the subject's arm, and mechanical energy was converted to electrical energy by means of periodic arm-bending motions. The optimized open-circuit voltage and short-circuit current density of approximately 125V and 17μA/cm<SUP>2</SUP>, respectively, were observed when a TFNG device underwent a compression test with a compressive force of 8N and driving frequency of 10Hz. This high-power generation enabled the instantaneous powering of 10 green light-emitting diodes that shone without any assistance from an external power source.
Field measurements of wind characteristics over hilly terrain within surface layer
Y.C. He,Q. S. Li,P.W. Chan 한국풍공학회 2014 Wind and Structures, An International Journal (WAS Vol.19 No.5
This paper investigates the topographic effects on wind characteristics over hilly terrain, based on wind data recorded at a number of meteorological stations in or near complex terrain. The multiply data sources allow a more detailed investigation of the flow field than is normally possible. Vertical profiles of mean and turbulent wind components from a Sodar profiler were presented and then modeled as functions of height and wind speed. The correlations between longitudinal and vertical wind components were discussed. The phenomena of flow separation and generation of vortices were observed. The distance-dependence of the topographic effects on gust factors was revealed subsequently. Furthermore, the canyon effect was identified and discussed based on the observations of wind at a saddle point between two mountain peaks. This study aims to further understanding of the characteristics of surface wind over rugged terrain. The presented results are expected to be useful for structural design, prevention of pollutant dispersion, and validation of CFD (computational fluid dynamics) models or techniques over complex terrains.