Browsing by Author "Chen, Ya-Ping"

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A new supramolecular POSS electroluminescent material
(2012)
Chu, Yu-Lin
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Cheng, Chih-Chia
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Chen, Ya-Ping
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Yen, Ying-Chieh
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Chang, Feng-Chih
A new polyhedral oligomeric silsesquioxane (POSS) core star-like supramolecular blue-light electroluminescent material, 4-uracilbutyl-1-methylpyrene ether (U-PY)/octakis[dimethyl(N-(6-acetamidopyridin- 2 yl))siloxy] silsesquioxane (ODAP-POSS) has been synthesized. This U-PY/ODAP-POSS contains eight pyrene chromophore arms formed through complementary uracil-diamidopyridine (U-DAP) pairs and exhibits high quantum efficiencies and good solution processing properties. The photoluminescence spectra of U-PY/ODAP-POSS (50/50) reveal that the color is stable after heating the sample at 150 degrees C for 1 h, in contrast, the pyrene/ODAP-POSS (50/50) shows significant thermal quenching. An electroluminescence (EL) device based on U-PY/ODAP-POSS exhibits higher maximum brightness and higher luminance efficiency relative to that of the U-PY. In addition, U-PY/ODAP-POSS also behaves as an effective dopant that enhances energy transfer from itself to MEH-PPV. The U-PY/ODAP-POSS-doped MEH-PPV blends exhibit high luminance efficiency, 1.45 times greater than MEH-PPV.
Aging, cognition, and the brain: effects of age-related variation in white matter integrity on neuropsychological function
(2019-07-03)
Fan, Yang-Teng
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Fang, Ya-Wen
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Chen, Ya-Ping
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Leshikar, Eric D.
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Lin, Ching-Po
Alterations in brain structure are viewed as neurobiological indicators which are closely tied to cognitive changes in healthy human aging. The current study used diffusion tensor imaging (DTI) tractography to investigate the relationship between age, brain variation in white matter (WM) integrity, and cognitive function. Sixteen younger adults (aged 20-28 years) and 18 healthy older adults (aged 60-75 years) underwent DTI scanning and a standardized battery of neuropsychological measures. Behaviorally, older adults exhibited poorer performance on multiple cognitive measures compared to younger adults. At the neural level, the effects of aging on theWM integrity were evident within interhemispheric (the anterior portion of corpus callosum) and transverse (the right uncinate fasciculus) fibers of the frontal regions, and the cingulum-angular fibers. Our correlation results showed that age-related WM differentially influenced cognitive function, with increased fractional anisotropy values in both the anterior corpus callosum and the right cingulum/angular fibers positively correlated with performance on the visuospatial task in older adults. Moreover, mediation analysis further revealed that the WM tract integrity of the frontal interhemspheric fibers was a significant mediator of age-visuospatial performance relation in older adults, but not in younger adults. These findings support the vulnerability of the frontal WM fibers to normal aging and push forward our understanding of cognitive aging by providing a more integrative view of the neural basis of linkages among aging, cognition, and brain.
Automatic Power Monitor (APM) in Switching Charger with Smooth Transition Loop Selector (STLS) for High-energy Throughput System
(2012)
Tsai, Tsu-Wei
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Peng, Ruei-Hong
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Su, Yi-Ping
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Chen, Ya-Ping
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Chen, Ke-Horng
This paper proposed a switch-based charger system instead of LDO-based charger for Li-Ion batteries. The automatic power monitor (APM) controls three main power delivery paths to generate five different charging cases. Moreover, with the proposed smooth transition loop selector (STLS), the charging process can transfer smoothly and never oscillate between two consecutive stages. Furthermore, the STLS can bear different batteries with wide built-in resistance variation by adjusting charging factors. The stability analysis proves that the stability of APM loop is guaranteed by only one Type-III compensator. The simulation results ensure the performance of the system controlled by APM even if the power source is unable to provide sufficient power.
Effects of Exercise Modes on Neural Processing of Working Memory in Late Middle-Aged Adults: An fMRI Study
(2019-09-04)
Chen, Feng-Tzu
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Chen, Ya-Ping
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Schneider, Stefan
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Kao, Shih-Chun
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Huang, Chih-Mao
Recent studies have highlighted the importance of regular exercise on cognitive function in aging populations, with aerobic exercise and cardiovascular fitness having received the largest amount of research attention. However, the relationship between exercise mode and cognitive function underlying behavioral modification and neural activation remains unknown. The present study, therefore, sought to examine the associations between different exercise modes and the working memory (WM) aspect of executive function as well as its task-evoked brain activation in the late middle-aged population. Seventy late middle-aged adults were classified into open-skill, closed-skill, or irregular exercise groups based on their participation in exercise activities prior to the study and then performed a spatial working memory (SWM) task while undergoing functional magnetic resonance imaging (fMRI) scanning. The results revealed that exercise groups, regardless of exercise modes, showed better SWM and physical fitness performance. Additionally, the open-skill group exhibited greater brain activation in the prefrontal lobe, anterior cingulate cortex/supplementary motor area (ACC/SMA), and hippocampus than those in the closed-skill group, suggesting a mode-sensitive compensatory mechanism in late middle-aged adults. These findings indicate that exercise promotes cognitive health, improves WM, and enhances neurocognitive scaffolding in late middle-aged adults and further suggest that various exercise modes can effectively modulate frontal and hippocampal function in the face of age-related neurocognitive declines, implications that may inform the development of exercise programs for the elderly.
Robust Switch-mode Charger with Bootstrap Detector (BSD) and Soft-start Embedded in Type III Compensation (SSEC) Technique
(2012)
Peng, Ruei-Hong
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Su, Yi-Ping
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Tsai, Tsu-Wei
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Chen, Ya-Ping
;
Chen, Ke-Horng
Bootstrap detector (BSD) and soft-start embedded in Type III compensation (SSEC) are implemented in the switch-mode charger to achieve high efficiency and ensure robustness charging process. The proposed BSD monitors the bootstrap voltage to avoid low efficiency and serious burning problem in both synchronous and non-synchronous charging modes. On the other hand, the SSEC avoids inrush current in start-up procedure of charger system without any external components and auxiliary circuits to greatly minimize the chip and footprint areas. The proposed robust switch-mode charger with the BSD and the SSEC technique was simulated in 0.25 mu m CMOS process. The fast charge current in constant current stage varies from 600 mA to 10 A with a 1.6 MHz operating switching frequency.