One-Dimensional Assembly on Two-Dimensions: AuCN Nanowire Epitaxy on Graphene for Hybrid Phototransistors

Jang, Jeongsu,Lee, Yangjin,Yoon, Jun-Yeong,Yoon, Hoon Hahn,Koo, Jahyun,Choe, Jeongheon,Jeon, Sungho,Sung, Jongbaek,Park, Jungwon,Lee, Won Chul,Lee, Hoonkyung,Jeong, Hu Young,Park, Kibog,Kim, Kwanpyo American Chemical Society 2018 Nano letters Vol.18 No.10

<P>The van der Waals epitaxy of functional materials provides an interesting and efficient way to manipulate the electrical properties of various hybrid two-dimensional (2D) systems. Here we show the controlled epitaxial assembly of semiconducting one-dimensional (1D) atomic chains, AuCN, on graphene and investigate the electrical properties of 1D/2D van der Waals heterostructures. AuCN nanowire assembly is tuned by different growth conditions, although the epitaxial alignment between AuCN chains and graphene remains unchanged. The switching of the preferred nanowire growth axis indicates that diffusion kinetics affects the nanowire formation process. Semiconducting AuCN chains endow the 1D/2D hybrid system with a strong responsivity to photons with an energy above 2.7 eV, which is consistent with the bandgap of AuCN. A large UV response (responsivity ∼10<SUP>4</SUP> A/W) was observed under illumination using 3.1 eV (400 nm) photons. Our study clearly demonstrates that 1D chain-structured semiconductors can play a crucial role as a component in multifunctional van der Waals heterostructures.</P> [FIG OMISSION]</BR>

Widely tunable band gaps of graphdiyne: an <i>ab initio</i> study

Koo, Jahyun,Park, Minwoo,Hwang, Seunghyun,Huang, Bing,Jang, Byungryul,Kwon, Yongkyung,Lee, Hoonkyung The Royal Society of Chemistry 2014 Physical chemistry chemical physics Vol.16 No.19

<P>Functionalization of graphdiyne, a two-dimensional atomic layer of sp–sp<SUP>2</SUP> hybrid carbon networks, was investigated through first-principles calculations. Hydrogen or halogen atoms preferentially adsorb on sp-bonded carbon atoms rather than on sp<SUP>2</SUP>-bonded carbon atoms, forming sp<SUP>2</SUP>- or sp<SUP>3</SUP>-hybridization. The energy band gap of graphdiyne is increased from ∼0.5 eV to ∼5.2 eV through the hydrogenation or halogenation. Unlike graphene, segregation of adsorbing atoms is energetically unfavourable. Our results show that hydrogenation or halogenation can be utilized for modifying the electronic properties of graphdiyne for applications to nano-electronics and -photonics.</P> <P>Graphic Abstract</P><P>Functionalization of graphdiyne, a two-dimensional atomic layer of sp–sp<SUP>2</SUP> hybrid carbon networks, was investigated through first-principles calculations. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cp00800f'> </P>

전자기-구조 상호 작용을 고려한 IPM 모터의 전자기 가진원 해석

남자현(Jahyun Nam),강치호(Chiho Kang),정근수(Geunsu Jeong),장건희(Gungee Jang) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12

We investigated the magnetic excitation of an IPM motor considering magnetic and structural interaction through finite element method. The finite element model was developed and the magnetic-structural coupled analysis was performed by using COMSOL, a commercial multiphysics finite element analysis software package. In the coupled analysis, the magnetic force calculated by using the Maxwell stress tensor was applied to the structure, and the magnetic finite element model was rearranged by using the moving mesh method. We showed that coupled analysis predicted the excitation frequency of 667 Hz (the first natural frequency of the rotor) of magnetic force undergoing rotor eccentricity. This paper will contribute the accurate prediction of magnetic excitation in electromechanical machines.

산소 농도에 따른 Alloy 617의 고온헬륨환경에서의 크립 및 산화거동

구자현,김대종,장창희,Koo, Jahyun,Kim, Daejong,Jang, Changheui 한국압력기기공학회 2011 한국압력기기공학회 논문집 Vol.7 No.2

Wrought nickel-base superalloys are being considered as the structural materials in very-high temperature gas-cooled reactors. To understand the effects of impurities, especially oxygen, in helium coolant on the mechanical properties of Alloy 617, creep tests were performed in high temperature flowing He environments with varying $O_2$ contents at 800, 900, and $1000^{\circ}C$. Also, creep life in static He was measured to simulate the pseudo-inert environment. Creep life was the longest in static He, while the shortest in flowing helium. In static He, impurities like $O_2$ and moisture were quickly consumed by oxidation in the early stage of creep test, which prevented further oxidation during creep test. Without oxidation, microstructural change detrimental to creep such as decarburization and internal oxidation were prevented, which resulted in longer creep life. On the other hand, in flowing He environment, surface oxides were not stable enough to act as diffusion barriers for oxidation. Therefore, extensive decarburization and internal oxidation under tensile load contributed to premature failure resulting in short creep life. Limited test in flowing He+200ppm $O_2$ resulted in even shorter creep life. The oxidation samples showed extensive spallation which resulted in severe decarburization and internal oxidation in those environments. Further test and analysis are underway to clarify the relationship between oxidation and creep resistance.

A case of maternal uniparental disomy of chromosome 20 detected during 1,000 high risk Korean NIPT

( Sohyun Shim ),( Junnam Lee ),( Youngjoo Jeon ),( Yongwook Jung ),( Jahyun Jang ),( Taeheon Lee ),( Eunhae Cho ),( Donghyun Cha ) 대한산부인과학회 2016 대한산부인과학회 학술대회 Vol.102 No.-

Chromosomal loss in trisomy to generate a disomic fetus can cause confined placental mosaicism and/or fetoplacental mosaicism. After trisomy rescue event, there is a risk of fetal uniparental disomy (UPD). The phenotypic consequences of UPD for several chromosomes are still unknown or poorly understood. In this study, we performed whole genome sequencing based NIPT (G-NIPTä) in 1,000 high risk Korean pregnancies and we have detected five cases of other chromosomal trisomies except chromosomes 21, 18 and 13. Chromosomes involved were 7 (1case), 8 (1 case), 16 (1 case) and 20 (2 cases). All three trisomy cases involving chromosomes 7 and 20 were investigated invasively for the presence of UPD. One case of trisomy 7 and one case of trisomy 20 showed normal karyotype at amniocentesis, respectively. However, 1 case of trisomy 20 revealed to have low level of mosaicism of trisomy 20 (47,XX,+20[2]/46,XX[40]) at amniocentesis. To rule out UPD, we performed chromosomal microarray from both amniotic fluid and maternal gDNA in all the three cases. We found 30Mb homozygosity spanning the centeromere in amniocentesis of the low level mosaic 20 case. This finding suggests nondisjunction error happened at meiosis. Then, by comparing all the SNPs of involved chromosomes between mother and fetus, maternal or paternal UPD can be decided. The low level mosaic 20 case can be diagnosed to have maternal UPD 20 and others didn't show any UPD pattern. Recently, maternal UPD 20 has been suggested as a new imprinting disorder with intrauterine growth restriction, short stature and prominent feeding difficulties with failure to thrive. To best of our knowledge, two cases of UPD were detected by following discordant NIPT and invasive testing which were a case of UPD 21 and a case of UPD 15 with fetal mosaicism. From this study, we showed the potential use of NIPT for the detection of UPD, especially when the trisomies of specific chromosomes with imprinting syndromes are detected by NIPT.

고온 수증기 환경에서 Ni기 초합금의 산화특성

김동훈,구자현,김대종,유영성,장창희,Kim, Donghoon,Koo, Jahyun,Kim, Daejong,Yoo, Young-Sung,Jang, Changheui 한국압력기기공학회 2011 한국압력기기공학회 논문집 Vol.7 No.2

To evaluate steam oxidation behaviours of Alloy 617 and Haynes 230, oxidation test were performed at $900^{\circ}C$ in steam and $steam+20\;vol.-%\;H_2$ environments. Oxidation rate in steam condition was similar to that in air for Alloy 617, while it was slightly lower for Haynes 230. When hydrogen was added to steam, oxidation rate was enhanced. Isolated $MnTiO_3$ particle were formed on $Cr_2O_3$ oxide layer and sub layer $Cr_2O_3$ were formed in steam and $steam+20\;vol.-%\;H_2$ for Alloy 617. On the other hands, $MnCr_2O_3$ layer were formed on top of $Cr_2O_3$ oxide layer for Haynes 230. The extensive sub layer $Cr_2O_3$ formation was resulted from the oxygen inward diffusion in such environments. When hydrogen was added, the oxide morphology was changed from polygonal to platelet because of the accelerated diffusion of cations under the oxide layer. In addition, decarburized zone was extended as hydrogen participated into the reactions causing carbide dissolution.

First female Korean child with Coffin-Lowry syndrome: a novel variant in RPS6KA3 diagnosed by exome sequencing and a literature review

Song Ari,Im Minji,Kim Min-Sun,Noh Eu Seon,Kim Chiwoo,Jang Jahyun,Lee Sae-Mi,Ki Chang-Seok,Cho Sung Yoon,Jin Dong-Kyu 대한소아내분비학회 2023 Apem Vol.28 No.1

Coffin-Lowry syndrome (CLS, OMIM # 303600) is a rare X-linked disorder caused by mutations in RPS6KA3. CLS is characterized by facial dysmorphism, digit abnormalities, developmental delays, growth retardation, and progressive skeletal changes in male patients. Females with CLS are variably affected, complicating diagnosis. Here, we describe the clinical and molecular findings in a female Korean child with CLS and review the associated literature. A 5-year-old girl presented with short stature and developmental delays. She had a coarse facial appearance characterized by a prominent forehead, hypertelorism, thick lips, and hypodontia. She also had puffy tapering fingers and pectus excavatum. We performed exome sequencing and identified a novel, likely pathogenic, heterozygous variant, c.326_338delinsCTCGAGAC (p.Val109Alafs*10), in RPS6KA3 (NM_004586.2). This is the first Korean female genetically diagnosed with CLS. In contrast to the delayed bone age reported in previous studies, our patient showed advanced bone age and central precocious puberty. CLS should be considered as a differential diagnosis of short stature, tapering fingers, and developmental delay. We suggest that molecular techniques can be a useful tool for diagnosis of rare disorders such as CLS because such conditions are not simple, and the associated spectrum of phenotypes can vary.