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Yew Min Sen,Kaur Rajinderdeep,Lee Wan Ling,Omar Hider Bin,Lee Yeong Shyan 아시아심장혈관영상의학회 2022 Cardiovascular Imaging Asia Vol.6 No.3
Contrast reflux from superior vena cava into azygos system may be mistaken for pathology. We report a case occurring during CT coronary angiography (CTCA) causing diagnostic uncertainty. A linear hyperdensity anterior and left of the upper thoracic vertebrae was seen during CTCA and mistaken for abnormal calcification. However, this was not seen on non-contrasted coronary calcium images. The hyperdensity correlated to the location of the unenhanced azygos vein seen on test bolus images. Although reported in CT pulmonary angiography, contrast in the azygos system is less common in CTCAs as the longer scan delay allows contrast washout. However, right arm contrast injection, the default for CTCA, is an association. Moreover, right heart and pericardial diseases are also potential causes. Cardiac imagers should be aware of this potential pitfall.
An Improved Symmetrically-Graded Doped-Channel Heterostructure Field-Effect Transistor
Ke-Hua Su,Wei-Chou Hsu,Chang-Luen Wu,Ching-Sung Lee,Po-Jung Hu,Yeong-Jia Chen,Yu-Shyan Lin 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.6
A new heterostructure field-effect transistor with an InGaAs symmetrically-graded doped-channel (SGDC) structure has been successfully investigated. The channel design demonstrated a reduced Coulomb scattering phenomenon by confining the conduction electrons away from the channel/spacer interface. Consequently, a higher current density, a higher breakdown voltage, a wider gate-voltage swing, a higher transconductance, a higher threshold voltage, and improved microwave and power characteristics were achieved by using the SGDC structure, as compared to those of conventional doped-channel devices. Besides, the AlGaAs/GaAs superlattice buffer structure was used to improve the high-temperature threshold-voltage characteristics.