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Ching-Sung Lee,Dong-Hai Huang,Jun-Chin Huang,Ke-Hua Su,Wei-Chou Hsu,Yeong-Jia Chen 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.4
A -doped In0.45Al0.55As/In0.53Ga0.47As/InAlGaAs/GaAs metamorphic high electron mobility transistor (MHEMT) using a Ni/Au-gate electrode has been successfully fabricated and demonstrated. Compared to conventional Au-gate devices with identical structures, the proposed device improves the kink-effect-related output conductance, the gate-voltage swing, the current drive capability, the breakdown characteristics, and the device power performance. Experimentally, a high extrinsic transconductance of 309 mS/mm, a high drain-source saturation current density of 573 mA/mm, an improved gate-voltage swing of 1.05 V with a corresponding saturation current density of 314 mA/mm, a high saturated output power of 11.3 dBm, and a high power gain of 23.8 dB with a power-added efficiency of 39.2 % are obtained for a 0.65 × 200 μm2 gate at 300 K. In addition, the measured fT and fmax are 49.1 and 61.7 GHz, respectively.
Ching-Sung Lee,Bo-I Chou,Wei-Chou Hsu,Ke-Hua Su 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6
This work reports a novel AlGaAs/InGaAsN/GaAs heterostructure field-eect transistor (HFET) by integrating a dilute In0:3Ga0:7AsN0:01 nitride-channel directly onto a GaAs substrate by using a molecular beam epitaxy (MBE) system. Introducing nitrogen doping into an In0:3Ga0:7As channel can effectively reduce the eective energy band gap, resulting in an improved electron confinement capability. The thermal threshold coeficient (∂Vth=∂T) is very low, -1.07 mV/K, with an improved high-temperature linearity (∂GV S=∂T) of only 0.33 mV/K. Besides, improved high-temperature device characteristics have been achieved at 450 (300) K, including a gate-voltage swing (GVS) of 1.15 (1.2) V, a two-terminal gate-drain breakdown voltage (BVGD) of -14.4 (-15.8) V and a turn-on voltage (Von) of 0.92 (1.147) V.
Ching-Sung Lee,Chia-Jeng Chian,Wei-Chou Hsu,Ke-Hua Su,Su-Jen Yu 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.4
This work provides comprehensive comparisons of the device characteristics, including the voltage gain, power performance, linearity and noise characteristics, for InAlAs/InGaAs/GaAs metamorphic high electron mobility transistors with respect to different indium contents in the InGaAs channel. Though the device with a high In-ratio InGaAs channel usually demonstrated improved high-frequency characteristics, the kink effects in their narrow-gap channel materials were found to seriously degrade the device performance. On the other hand, the low In-ratio channel device had characteristics advantageous for high-gain and high-linearity applications while the device with a compromised channel composition design was suitable for high-power circuit applications. This work provides comprehensive comparisons of the device characteristics, including the voltage gain, power performance, linearity and noise characteristics, for InAlAs/InGaAs/GaAs metamorphic high electron mobility transistors with respect to different indium contents in the InGaAs channel. Though the device with a high In-ratio InGaAs channel usually demonstrated improved high-frequency characteristics, the kink effects in their narrow-gap channel materials were found to seriously degrade the device performance. On the other hand, the low In-ratio channel device had characteristics advantageous for high-gain and high-linearity applications while the device with a compromised channel composition design was suitable for high-power circuit applications.
Lee, Hyun-Joo,Lim, Yoon-Ki,Chang, Sang-Ho,Min, Kwan-Sik,Han, Ching-Tack,Hwang, Sue-Yun Korea Genome Organization 2007 Genomics & informatics Vol.5 No.4
The earliest stages of mammalian embryogenesis are governed by the activity of maternally inherited transcripts and proteins. Cytoplasmic polyadenylation of selected maternal mRNA has been reported to be a major control mechanism of delayed translation during preimplantation embryogenesis in mice. The presence of cis-elements required for cytoplasmic polyadenylation (e.g., CPE) can serve as a useful tag in the screening of maternal genes partaking in key functions in the transcriptionally dormant egg and early embryo. However, due to its relative simplicity, UA-rich sequences satisfying the canonical rule of known CPE consensus sequences are often found in the 3'-UTR of maternal transcripts that do not actually undergo cytoplasmic polyadenylation. In this study, we developed a method to confirm the validity of candidate CPE sequences in a given gene by a multiplex comparison of 3'-UTR sequences between mammalian homologs. We found that genes undergoing cytoplasmic polyadenylation tend to create a conserved block around the CPE, while CPE-like sequences in the 3'-UTR of genes lacking cytoplasmic polyadenylation do not exhibit such conservation between species. Through this cross-species comparison, we also identified an alternative CPE in the 3'-UTR of tissue-type plasminogen activator (tPA), which is more likely to serve as a functional element. We suggest that verification of CPEs based on sequence conservation can provide a convenient tool for mass screening of factors governing the earliest processes of mammalian embryogenesis.
Ching-Fent Tsai,Kun-Teng Wang,Lih-Geeng Chen,Chia-Jung Lee,Sung-Hui Tseng,Ching-Chiung Wang 한국식품영양과학회 2014 Journal of medicinal food Vol.17 No.4
Vitis thunbergii Sieb. et Zucc. var. taiwaniana Lu (VT) is an indigenous plant in Taiwan that is traditionally used for promoting joint health. In this study, we used in vitro primary human chondrocytes (PHCs) and two in vivo animal models to evaluate the anti-inflammatory effects of VT on arthritis. Results showed that the water extract of the stems and roots from VT (VT-SR) was rich in flavones and phenols with 1.1 mg/g of resveratrol, 6.7 mg/g of hopeaphenol, and 5.1 mg/g of (+)-e-viniferin. VT-SR significantly scavenged DPPH radicals and inhibited prostaglandin E2 (PGE2) production in lipopolysaccharide (LPS)-induced PHCs without exhibiting significant cytotoxicity. In in vivo models, the VT-SR (500 mg/kg) significantly decreased serum PGE2 and knee 2-18F-fluoro-2-deoxy-D-glucose (18F-FDG) levels in LPS-induced acute inflammatory arthritis in rabbits. In addition, dietary supplementation with VT-SR for 28 days significantly alleviated type II collagenase-induced rat osteoarthritis with improvements in weight bearing and range of motion tests. In conclusion, our results suggest that the VT-SR is a good candidate for developing dietary supplements to prevent joint deterioration and inhibit inflammation.
Pulmonary Arterial Thrombosis in a Patient With an Atrial Septal Defect and Eisenmenger Syndrome
Ching-Wei Lee,Shao-Sung Huang,Po-Hsun Huang 대한심장학회 2012 Korean Circulation Journal Vol.42 No.11
Pulmonary hypertension is characterized by elevated pulmonary arterial pressure and secondary right ventricular failure. A thromboembolic occlusion of the proximal or distal pulmonary vasculature results in chronic thromboembolic pulmonary hypertension. We report an uncommon case that presented to our hospital with symptoms of dyspnea on exertion over 2 years. The patient had been treated for profound pulmonary thrombosis and right ventricular failure with adequate anticoagulation and sildenafil. Our echocardiography disclosed a large atrial septal defect with severe pulmonary hypertension and right ventricular failure. A diagnosis of Eisenmenger syndrome with pulmonary artery thrombosis was made. Although Eisenmenger syndrome with pulmonary thrombosis is well described in western societies,a huge pulmonary thrombosis is seldom reported in eastern countries. Profound pulmonary thrombosis may obfuscate the actual diagnosis of pulmonary artery hypertension with underlying congenital heart disease. A physical examination and echocardiography are essential in patients with pulmonary hypertension.
Ching-Wei Lee,Shih-Hsien Sung,Wei-Ming Huang,Yi-Lin Tsai,Hsiang-Yao Chen,Chiao-Po Hsu,Chun-Che Shih,Kuo-Piao Chung 대한심장학회 2019 Korean Circulation Journal Vol.49 No.6
Background and ObjectivesAge is a traditional risk factor for open-heart surgery. The efficacy and safety of transcatheter edge-to-edge mitral valve repair, using MitraClip (Abbott Vascular), has been demonstrated in patients with severe mitral regurgitation (MR). Since octogenarians or older patients are usually deferred to receive open-heart surgery, the main interest of this study is to elucidate the procedural safety and long-term clinical impact of MitraClip in elderly patients. MethodsPatients with symptomatic severe MR were evaluated by the heart team. For those with high or prohibitive surgical risks, transcatheter mitral valve repair was performed in hybrid operation room. Transthoracic echocardiography (TTE), blood tests, and six-minute walk test (6MWT) were performed before, 1-month, 6-months, and 1 year after index procedure. ResultsA total of 46 consecutive patients receiving MitraClip procedure were enrolled. Nineteen patients (84.2±4.0 years) were over 80-year-old and 27 (73.4±11.1 years) were younger than 80. Compare to baseline, the significant reduction in MR severity was achieved after the procedure and sustained. All the patients benefited from significant improvement in New York Heart Association functional class. The 6-minute walk test (6MWT) increased from 259±114 to 319±92 meters (p=0.03) at 1 year. The overall 1-year survival rate was 80% in the elderly and 88% in those <80 years, p=0.590. Baseline 6MWT was a predictor for all-cause mortality (odds ratio, 0.99; 95% confidence interval, 0.982–0.999; p=0.026) after the MitraClip procedure. ConclusionsTrans-catheter edge-to-edge mitral valve repairs are safe and have positive clinical impact in subjects with severe MR, even in advanced age.