Browsing by Author "Chen, Peng"

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A meta-analysis of genome-wide association studies for adiponectin levels in East Asians identifies a novel locus near WDR11-FGFR2
(2014-02-15)
Wu, Ying
;
Gao, He
;
Li, Huaixing
;
Tabara, Yasuharu
;
Nakatochi, Masahiro
Blood levels of adiponectin, an adipocyte-secreted protein correlated with metabolic and cardiovascular risks, are highly heritable. Genome-wide association (GWA) studies for adiponectin levels have identified 14 loci harboring variants associated with blood levels of adiponectin. To identify novel adiponectin-associated loci, particularly those of importance in East Asians, we conducted a meta-analysis of GWA studies for adiponectin in 7827 individuals, followed by two stages of replications in 4298 and 5954 additional individuals. We identified a novel adiponectin-associated locus on chromosome 10 near WDR11-FGFR2 (P 3.0 10(14)) and provided suggestive evidence for a locus on chromosome 12 near OR8S1-LALBA (P 1.2 10(7)). Of the adiponectin-associated loci previously described, we confirmed the association at CDH13 (P 6.8 10(165)), ADIPOQ (P 1.8 10(22)), PEPD (P 3.6 10(12)), CMIP (P 2.1 10(10)), ZNF664 (P 2.3 10(7)) and GPR109A (P 7.4 10(6)). Conditional analysis at ADIPOQ revealed a second signal with suggestive evidence of association only after conditioning on the lead SNP (P-initial 0.020; P-conditional 7.0 10(7)). We further confirmed the independence of two pairs of closely located loci (2 Mb) on chromosome 16 at CMIP and CDH13, and on chromosome 12 at GPR109A and ZNF664. In addition, the newly identified signal near WDR11-FGFR2 exhibited evidence of association with triglycerides (P 3.3 10(4)), high density lipoprotein cholesterol (HDL-C, P 4.9 10(4)) and body mass index (BMI)-adjusted waisthip ratio (P 9.8 10(3)). These findings improve our knowledge of the genetic basis of adiponectin variation, demonstrate the shared allelic architecture for adiponectin with lipids and central obesity and motivate further studies of underlying mechanisms.
InGaN-based light-emitting diodes grown and fabricated on nanopatterned Si substrates
(2010-05-17)
Deng, Dongmei
;
Yu, Naisen
;
Wang, Yong
;
Zou, Xinbo
;
Kuo, Hao-Chung
InGaN-based light-emitting diodes (LEDs) were grown and fabricated on nanoscale patterned Si (111) substrates (NPSi). Using anodized aluminum oxide as the etch mask, the NPSi was prepared with an average nanopore diameter of 150 nm and interpore distance of 120 nm. LEDs grown on NPSi exhibit relaxed tensile stress relative to the ones grown on microscale patterned Si (111) substrates (MPSi). Nanoheteroepitaxial lateral overgrowth was significantly promoted on NPSi, which led to extensive dislocation bending and annihilation. The devices made on NPSi exhibit lower leakage current and higher light output power as compared with those on MPSi. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3427438]
Material characteristics of InGaN based light emitting diodes grown on porous Si substrates
(2011-01-15)
Deng, Dongmei
;
Chiu, Ching-Hsueh
;
Kuo, Hao-Chung
;
Chen, Peng
;
Lau, Kei May
InGaN/GaN multiple quantum wells light emitting diodes (LEDs) with 2 mu m thick crack-free GaN buffer layers were grown on porous Si substrates by metalorganic chemical vapor deposition. The material properties of LEDs grown on porous Si were studied in comparison with LEDs grown on grid-patterned Si. The (1 0 (1) over bar 5) asymmetric reciprocal space mapping (RSM) results indicate that LEDs grown on porous Si have less lattice tilt or distortion than those grown on grid-patterned Si. Both RSM and micro-photoluminescence (micro-PL) measurements suggest that multiple quantum wells grown on porous Si are less stressed. Mechanisms behind this partial strain relaxation are discussed. (C) 2010 Elsevier B.V. All rights reserved.
Unexpected Giant Microwave Conductivity in a Nominally Silent BiFeO3 Domain Wall
(1970-01-01)
Huang, Yen-Lin
;
Zheng, Lu
;
Chen, Peng
;
Cheng, Xiaoxing
;
Hsu, Shang-Lin
Nanoelectronic devices based on ferroelectric domain walls (DWs), such as memories, transistors, and rectifiers, have been demonstrated in recent years. Practical high-speed electronics, on the other hand, usually demand operation frequencies in the gigahertz (GHz) regime, where the effect of dipolar oscillation is important. Herein, an unexpected giant GHz conductivity on the order of 10(3) S m(-1) is observed in certain BiFeO3 DWs, which is about 100 000 times greater than the carrier-induced direct current (dc) conductivity of the same walls. Surprisingly, the nominal configuration of the DWs precludes the alternating current (ac) conduction under an excitation electric field perpendicular to the surface. Theoretical analysis shows that the inclined DWs are stressed asymmetrically near the film surface, whereas the vertical walls in a control sample are not. The resultant imbalanced polarization profile can then couple to the out-of-plane microwave fields and induce power dissipation, which is confirmed by the phase-field modeling. Since the contributions from mobile-carrier conduction and bound-charge oscillation to the ac conductivity are equivalent in a microwave circuit, the research on local structural dynamics may open a new avenue to implement DW nano-devices for radio-frequency applications.