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Effective shape-controlled growth of monolayer MoS2 flakes by powder-based chemical vapor deposition

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Nano Research 2017年第1期10卷 255-262页

作者： Sang Yoon Yang Gi Woong Shim Seung-bum Seo Sung-Yool Choi Graphene Research Center (GRC) Center for Advanced Materials Discovery for 3D Displays (CAMD3) School of Electrical EngineeringKorea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea

In the recent years, transition-metal dichalcogenides such as MoS2 have attracted considerable attention owing to their unique structure and electronic properties. Chemical vapor deposition （CVD） is a popular method for producing MoS2 flakes with different shapes. Here, we report an effective method for achieving a broad range of shape evolution in CVD-grown monolayer MoS2 flakes. By controlling the S and MoO3 temperatures, the shape of the monolayer MoS2 flakes was varied from hexagonal to triangular via intermediate shapes such as truncated and multi-apex triangles. The shape evolution of the MoS2 flakes can be explained by introducing the term “nominal Mo：S ratio”, which refers to the amount of loaded MoO3 and evaporated S powders. By using the nominal Mo：S ratio, we predicted the potential reaction atmosphere and effectively controlled the actual proportion of MoO3-x with respect to S in the growth region, along with the growth temperature. From the systematic investigation of the behavior of the shape evolution, we developed a shape-evolution diagram, which can be used as a practical guide for producing CVD-grown MoS2 flakes with desired shapes

关键词： molybdenum disulfide CVD growth shape evolution diagram growth condition

Secure and Efficient Data Transmission Scheme Based on Physical Mechanism

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Computers, Materials & Continua 2023年第5期75卷 3589-3605页

作者： Ping Zhang Haoran Zhu Wenjun Li Osama Alfarraj Amr Tolba gwang-jun Kim School of Computer Science Hunan University of Technology and BusinessChangsha410205China School of Computer&Communication Engineering Changsha University of Science&TechnologyChangsha410004China Computer Science Department Community CollegeKing Saud UniversityRiyadh11437Saudi Arabia Department of Computer Engineering Chonnam National UniversityGwangju61186Korea

Many Internet of things application scenarios have the characteristics of limited hardware resources and limited energy supply,which are not suitable for traditional security *** security technology based on the physicalmechanism has attracted extensive *** to improve the key generation rate has always been one of the urgent problems to be solved in the security technology based on the physical *** this paper,superlattice technology is introduced to the security field of Internet of things,and a high-speed symmetric key generation scheme based on superlattice for Internet of things is *** order to ensure the efficiency and privacy of data transmission,we also combine the superlattice symmetric key and compressive sensing technology to build a lightweight data transmission scheme that supports data compression and data encryption at the same *** analysis and experimental evaluation results show that the proposed scheme is superior to the most closely related work.

关键词： Data transmission key generation data privacy compressive sensing Internet of Things(IoT)

Sandwich-type ordered mesoporous carbon/graphene nanocomposites derived from ionic liquid

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Nano Research 2016年第9期9卷 2696-2706页

作者： Ho Seok Kim Young Hwan Kim Kwang Chul Roh Kwang-bum Kim Lab of Energy Storage Materials Department of Material Science & EngineeringYonsei UniversitySeou1120749Republic of Korea Energy & Environmental Division Korea Institute of Ceramic Engineering & TechnologyJinju 52851Republic of Korea

Sandwich-type ordered mesoporous carbon/graphene nanocomposites were successfully synthesized using 2D ordered mesoporous silica/graphene nanocomposites as the hard template and an ionic liquid as a N-rich carbon source. We used an ionic liquid of 1-(3-cyanopropyl)-3-methylimidazolium dicyanamide containing nitrile groups (–CN) in the cation and anion as a carbon precursor for the preparation of the nanocomposites. Nitriles do not decompose under thermal treatment in an inert gas atmosphere, but leave significant amounts of N-rich carbon materials. The nanocomposites had a large surface area (1,316 m2·g–1), an average pore diameter of 5.9 nm, and high electrical conductivity. The nanocomposite electrode showed a high specific capacitance of 190 F·g–1at 0.5 A·g–1in 1 M TEABF4/AN electrolyte and a good rate capability between 0 and 2.7 V for supercapacitor (or ultracapacitor) applications. [Figure not available: see fulltext.] © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

关键词： ionic liquid-derived carbon ordered mesoporous carbon/graphene nanocomposite 2D graphene nanocomposite supercapacitor

Photosynthetic activity and expression of genes encoding antioxidant enzymes in the leaves of alanine am inotransferase mutant （Oryza sativa L.） against salt stress

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Photosynthetic activity and expression of genes encoding ant...

Changes in endoscopic patterns before and during COVID-19 outbreak:Experience at a single tertiary center in Korean

The 3rd Asian and Oceanian Conference on Photobiology

作者： Kyoung nam im Gynheung An In Ho Park Chin bum Lee Department of Biology Dong-eui UniversityBusanKorea National Research Laboratory of Plant Functional Genomics Division of Molecular and Life SciencesPohang University of Science and Technology （POSTECH）Pohang 790-784Republic of Korea Department of Biology Donga University Busan Korea Department of Biology Dong-eui University Busan Korea

＜正＞T-DNA tagging lines in rice, 1C-12812 （Oriza sativa cv. Hwayoung） and 3A-10591 （Oriza sativa cv. Dongjin） in which T-DNA was inserted into the 9th exon （Chr 3） and 4th intron （Chr 10） of OsAlaAT, respectively were isolated from T-DNA mutagenized populations. Two homozygote mutants were selected by genotyping with AlaAT1 and AlaAT-specific primers. In case of seed length and growth of the mutant, 1C-12812 and 3A-10591 showed smaller and weaker phenotypes than wild type. The photosynthetic activities （Fv/Fm and qQ） of 3A-10591 were decreased than control under salt stress （NaCl 300mM, 24h treatment）. However, PSⅡ activity of 1C-12812 was not decreased in comparison with 3A-10591. The mRNA levels of cytosolic ascrobate peroxidase （cAPX） and peroxidase Ⅱ（POX Ⅱ） in the leaves of 1C-12812 were determined by RT-PCR under different salt concentrations. mRNA levels of cAPX were increased against salt treatment in both control and mutant rice. However, mRNA level of POX Ⅱ was decreased dramatically and the total POX activity was also decreased under salt stress （NaCl 300mM, 24h treatment） in the leaves of 1C-12812. These results indicate that the loss of AlaAT activity may affect the photosynthetic activities related to photorespiration and the activities/synthesis of antioxidant enzymes, especially POX Ⅱ.

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World Journal of Clinical Cases 2021年第15期9卷 3576-3585页

作者： Kook Hyun Kim Sung bum Kim Tae Nyeun Kim Division of Gastroenterology and Hepatology Department of Internal MedicineYeungnam University College of MedicineDaegu 42415South Korea

BACKGROUND The surge of coronavirus disease 2019(COVID-19)patients has markedly influenced the treatment policies of tertiary hospitals because of the need to protect medical staff and contain viral transmission,but the impact COVID-19 had on emergency gastrointestinal endoscopies has not been *** To compare endoscopic activities and analyze the clinical outcomes of emergency endoscopies performed before and during the COVID-19 outbreak in Daegu,the worst-hit region in South *** This retrospective cohort study was conducted on patients aged≥18 years that underwent endoscopy from February 18 to March 28,2020,at a tertiary hospital in ***,laboratory findings,types and causes of emergency endoscopies,and endoscopic reports were reviewed and compared with those obtained for the same period in 2018 and *** From February 18 to March 28,a total of 366 emergent endoscopic procedures were performed:Upper endoscopy(170,50.6%),endoscopic retrograde cholangiopancreatography(113,33.6%),and colonoscopy with sigmoidoscopy(53,15.8%).The numbers of procedures performed in 2018 and 2019 dropped by 48.8%and 54.8%,respectively,compared with those in *** the COVID-19 outbreak,the main indications for endoscopy were melena(36.7%),hematemesis(30.6%),and hematochezia(10.2%).Of the endoscopic abnormalities detected,gastrointestinal bleeding was the most common:39 cases in 2018,51 in 2019,and 35 in *** The impact of COVID-19 is substantial and caused dramatic reductions in endoscopic procedures and changes in patient ***-term follow-up studies are required to determine the effects of COVID-19 induced changes in the endoscopy field.

关键词： COVID-19 Coronavirus Endoscopy Emergency endoscopy

Silicon nanowire ratioed inverters on bendable substrates

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Nano Research 2018年第5期11卷 2586-2591页

作者： Jeongje Moon Yoonjoong Kim Doohyeok Lim Kyeungmin im Sangsig Kim Department of Electrical Engineering Korea University 145 Anam-ro Seongbuk-gu Seoul 02841 Republic of Korea LED PKG Development Group Samsung Electronics Co. Ltd. 1 Samsung-ro Yongin-si Gyeonggi-do 17113 Republic of Korea

In this study, we demonstrate the performance of silicon nanowire （SiNW） n-metal oxide semiconductor （MOS） and p-MOS ratioed inverters that are fabricated on bendable substrates. The electrical characteristics of the fabricated devices can be controlled by adjusting the load voltage. The logic swings of the n- and p-MOS ratioed inverters at a low supply voltage of 1V are 80% and 96%, respectively. The output voltage level of the p-MOS ratioed inverter is close to rail-to-rail operation. The device also exhibits stable characteristics with good fatigue properties. Our bendable SiNW ratioed inverters show promise as a candidate building block for future bendable electronics.

关键词： silicon nanowire ratioed inverter n-metal oxide semicon-ductor (MOS) inverter p-MOS inverter bendable substrate

Naturally occurring hepatitis B virus reverse transcriptase mutations related to potential antiviral drug resistance and liver disease progression

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World Journal of Gastroenterology 2018年第16期24卷 1708-1724页

作者： Yu-Min Choi So-Young Lee bum-Joon Kim Department of Microbiology and immunology Biomedical Sciences Liver Research Institute and Cancer Research Institute Seoul National University College of Medicine

The annual number of deaths caused by hepatitis B virus(HBV)-related disease, including cirrhosis and hepatocellular carcinoma(HCC), is estimated as 887000. The reported prevalence of HBV reverse transcriptase(RT) mutation prior to treatment is varied and the impact of preexisting mutations on the treatment of na?ve patients remains controversial, and primarily depends on geographic factors, HBV genotypes, HBe Ag serostatus, HBV viral loads, disease progression, intergenotypic recombination and co-infection with HIV. Different sensitivity of detection methodology used could also affect their prevalence results. Several genotype-dependent HBV RT positions that can affect the emergence of drug resistance have also been reported. Eight mutations in RT(rtL80I, rtD134N, rtN139K/T/H, rtY141F, rtM204I/V, rtF221Y, rtI224V, and rtM309K) are significantly associated with HCC progression. HBe Ag-negative status, low viral load, and genotype C infection are significantly related to a higher frequency and prevalence of preexisting RT mutations. Preexisting mutations are most frequently found in the A-B interdomain of RT which overlaps with the HBs Ag "a" determinant region, mutations of which can lead to simultaneous viral immune escape. In conclusion, the presence of baseline RT mutations can affect drug treatment outcomes and disease progression in HBVinfected populations via modulation of viral fitness and host-immune responses.

关键词： polymerase hepatocellular carcinoma reverse transcriptase preexisting mutations hepatitis B virus

Enhanced Electrical Properties in Carbon Nanotube/Poly （3-hexylthiophene） Nanocomposites Formed Through Non-Covalent Functionalization

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Nano Research 2011年第11期4卷 1129-1135页

作者： Sung Hye Park Sung Hwan Jin gwang Hoon Jun SeokwoO Jeon Soon Hyung Hong Department of Material Science and Engineering Korea Advanced Institutc of Science Technol0gy Daejeon 305＇701 Republic of Korea

Poly（3-hexylthiophene）（P3HT） has received much attention as a good candidate to replace inorganic semiconductors for flexible electronics due to its solution-processability. However, the low charge mobility of P3HT is an obstacle to its commercialization. To overcome this problem, we propose a new non-covalent functionalization method for carbon nanotubes （CNTs） for use in CNT/P3HT nanocomposites. By using modified pyrene molecules with hydrophobic long alkyl chains, the non-covalently functionalized CNTs can become well dispersed in hydrophobic solutions and organic semiconductor matrices. Fabrication of organic thin-film transistors （OTFTs） from the non-covalently functionalized CNT/organic semiconductor nanocomposites shows that our non-covalent functionalization method significantly reduces damage to CNTs during functionalization when compared with covalent functionalization by treatment with acids. The OTFTs show 15 times enhancement of field effect mobility （1.5 × 10^-2 cm^2/（V.s）） compared to the mobility of OTFTs made from pure P3HT. This enhancement is achieved by addition of only 0.25 wt% of CNTs to P3HT.

关键词： Carbon nanotubes conjugated polymers nanocomposites organic thin film transistors

Prognostic role of plasma level of angiopoietin-1,angiopoietin-2,and vascular endothelial growth factor in hepatocellular carcinoma

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World Journal of Gastroenterology 2021年第27期27卷 4453-4467页

作者： gwang Hyeon Choi Eun Sun Jang Jin-Wook Kim Sook-Hyang Jeong Department of Internal Medicine Seoul National University Bundang HospitalSeoul National University College of MedicineSeongnam 13620South Korea

BACKGROUND Most hepatocellular carcinomas(HCCs)are hypervascular,with characteristic features of hepatic arterial supply to the *** factors involved in tumor angiogenesis include angiopoietin-1(Ang-1),angiopoietin-2(Ang-2),and vascular endothelial growth factor(VEGF).Aim To investigate the profiles of plasma levels of angiogenesis markers in patients with HCC and evaluate their roles in predicting overall survival(OS)and progression-free survival(PFS).METHODS Plasma samples from 240 prospectively enrolled HCC patients in the very early to advanced stages were used to measure the levels of Ang-1,Ang-2,and *** associations with clinical characteristics,OS,and PFS were *** The median plasma levels of Ang-1,Ang-2,and VEGF were 3216 pg/mL,1684 pg/mL,and 26.5 pg/mL,*** plasma level of Ang-2 showed a significant increase from early stage[Barcelona clinic liver cancer(BCLC)A]to intermediate(BCLC B)and advanced stage HCC(BCLC C/D),whereas Ang-1,VEGF,and alpha-fetoprotein(AFP)levels in the plasma did not show any such *** analysis,propensity score-matched analysis,and timedependent receiver operating curve analysis revealed that Ang-2 levels had the highest predictive power for OS and *** Ang-1 nor VEGF was significantly associated with OS or *** neutrophil-to-lymphocyte ratio was an independent factor for OS and *** The plasma levels of Ang-2 correlated with liver function,tumor stage,and tumor invasiveness,showing better performance in predicting OS and PFS than AFP,Ang-1,or VEGF.

关键词： Hepatocellular carcinoma Angiogenesis Biomarker Prognosis Survival