Novel chemical route for atomic layer deposition of MoS2 thin film on SiO2/Si substrate.

Jin, Zhenyu,Shin, Seokhee,Kwon, Do Hyun,Han, Seung-Joo,Min, Yo-Sep RSC Pub 2014 Nanoscale Vol.6 No.23

<P>Recently MoS2 with a two-dimensional layered structure has attracted great attention as an emerging material for electronics and catalysis applications. Although atomic layer deposition (ALD) is well-known as a special modification of chemical vapor deposition in order to grow a thin film in a manner of layer-by-layer, there is little literature on ALD of MoS2 due to a lack of suitable chemistry. Here we report MoS2 growth by ALD using molybdenum hexacarbonyl and dimethyldisulfide as Mo and S precursors, respectively. MoS2 can be directly grown on a SiO2/Si substrate at 100 C via the novel chemical route. Although the as-grown films are shown to be amorphous in X-ray diffraction analysis, they clearly show characteristic Raman modes (E(1)2g and A1g) of 2H-MoS2 with a trigonal prismatic arrangement of S-Mo-S units. After annealing at 900 C for 5 min under Ar atmosphere, the film is crystallized for MoS2 layers to be aligned with its basal plane parallel to the substrate.</P>

Urban particulate matter in air pollution penetrates into the barrier-disrupted skin and produces ROS-dependent cutaneous inflammatory response <i>in vivo</i>

Jin, Seon-Pil,Li, Zhenyu,Choi, Eun Kyung,Lee, Serah,Kim, Yoen Kyung,Seo, Eun Young,Chung, Jin Ho,Cho, Soyun Elsevier 2018 Journal of dermatological science Vol.91 No.2

<P><B>Abstract</B></P> <P><B>Background</B></P> <P>Particulate matter (PM) is an integral part of air pollution, which is a mixture of particles suspended in the air. Recently, it has been reported that PM is associated with increased risks of skin diseases, especially atopic dermatitis in children. However, it is unclear if PM directly goes into the skin and what mechanisms are involved in response to PM.</P> <P><B>Objective</B></P> <P>To see whether PM could penetrate into the barrier-disrupted skin, produce reactive oxygen species (ROS), and elicit an inflammatory response.</P> <P><B>Methods</B></P> <P>We collected PMs during a winter in Seoul and used cultured keratinocytes for <I>in vitro</I> study and tape-stripped BALB/c mice for <I>in vivo</I> study.</P> <P><B>Results</B></P> <P>Keratinocyte cytotoxicity increased in a dose-dependent manner by PM treatment. IL-8 and MMP-1 mRNA expression and protein levels were significantly increased compared to control by qPCR and ELISA, respectively. Cellular ROS production was increased by PM treatment, and antioxidant N-acetyl cysteine pretreatment prevented induction of inflammatory cytokines IL-8 and MMP-1. In PM-treated keratinocytes, electron-dense subcellular particles were observed by transmission electron microscopy. PM was observed inside hair follicles in both intact and barrier-disrupted skin <I>in vivo</I>. Additionally, intercellular penetration of PM was seen in the barrier-disrupted skin. Repeated PM application induced epidermal thickening and dermal inflammation with neutrophil infiltration. Finally, N-acetyl cysteine could ameliorate skin inflammation induced by PM application.</P> <P><B>Conclusion</B></P> <P>PM penetrates into the barrier-disrupted skin, causing inflammation, demonstrating detrimental effects in the skin.</P> <P><B>Highlights</B></P> <P> <UL> <LI> It is unclear if particulate matter (PM) directly goes into the skin. </LI> <LI> We provide visual images of PM penetrating into epidermis in the barrier-disrupted skin. </LI> <LI> Repeated PM application leads to cutaneous inflammation via ROS-dependent manner. </LI> <LI> It may have clinical implications especially for patients with deficient skin barrier including atopic dermatitis, diabetics. </LI> </UL> </P>

원자층증착법으로 성장시킨 MoS₂ 박막을 다른 기판으로 이전하기

김진우(Zhenyu Jin),김성준(Sungjoon Kim),민요셉(Yo-Sep Min) 한국기계가공학회 2017 한국기계가공학회 춘추계학술대회 논문집 Vol.2017 No.4

CDF-based Scheduling for Downlink NOMA

Zhenyu Cao,Yangqian Hu,Hu Jin 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.2

With the rapid development of 5G systems, non-orthogonal multiple access (NOMA) system has been considerably discussed in the literature. As well, the combination of traditional transmission technologies and NOMA will also bring performance improvements. In this paper, for downlink multi-user communications, we apply the cumulative distribution function (CDF) based scheduling along with NOMA to improve the system performance. In particular, a novel power allocation scheme is proposed for NOMA that allows two users to receive data simultaneously. Through simulations, wee show that the proposed scheme can achieve higher throughput than the conventional CDF-based scheduling.

Thermo-Mechanical Coupling Analysis of the Actuating Mechanism in a High Speed Press

Jin Cheng,Zhendong Zhou,Yixiong Feng,Zhenyu Liu,Yangyan Zhang 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.5

In order to ensure the manufacturing precision of an ultra-precision high speed press, an integrated thermo-mechanical coupling model of its actuating mechanism is proposed, which includes the mechanical models of the slider and crankshaft, the thermal models for calculating the heat generation powers at different bearings as well as the heat transfer and heat dissipation in the actuating mechanism. The validity of the proposed thermo-mechanical coupling model is verified by a thermal equilibrium experiment when the press operates under the full load of 3000kN at 300 rpm. A sensitivity analysis is conducted to investigate the simulation errors resulting from the variation of the ambient temperature, the results of which demonstrate that the average ambient temperature should be applied for improving simulation accuracy. Then the thermal stiffness of the actuating mechanism and the thermo-mechanical coupling characteristics of different parts are analyzed by the proposed model with the average ambient temperature applied. The influences of the thermally induced loads on the thermal stiffness are discussed in detail. It is concluded that the temperature rise of the actuating mechanism in the stamping process of a high speed press should be fully considered in the design phase for ensuring its manufacturing precision.

Energetics and Atomic Structures of Cu₂Te Overlayers on CdTe(111)

Choi, Jin-Ho,Zhu, Wenguang,Ho, Kai-Ming,Wang, Deliang,Zhang, Zhenyu American Chemical Society 2015 The Journal of Physical Chemistry Part C Vol.119 No.9

<P>Although Cu<SUB>2</SUB>Te is widely used as a back contact material in CdTe solar cells, the exact atomic structure of the Cu<SUB>2</SUB>Te/CdTe interface remains unclear. Using first-principles calculations within density functional theory, we search for possible structures of Cu<SUB>2</SUB>Te overlayers on CdTe(111) surfaces based on our recent theoretical determination of a stable layered structure of bulk Cu<SUB>2</SUB>Te. We discover that the unstrained bulklike configuration is energetically more favorable than various epitaxial configurations because of the significant energy costs associated with the in-plane strain, even though the first epitaxial overlayer is already more stable than bulk Cu<SUB>2</SUB>Te. Our thermodynamic analysis further confirms that the unstrained bulklike interface structure is still stable at typical experimental growth temperatures (∼700 K). It is also found that van der Waals forces play a considerable role in the stacking of the Cu<SUB>2</SUB>Te overlayers. These findings are discussed in connection with existing and new experimental results and will likely stimulate future systematic experiments.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2015/jpccck.2015.119.issue-9/jp511776e/production/images/medium/jp-2014-11776e_0003.gif'></P>

Research Method and Prediction Model of PM2.5 in Cities

Yang, ZhenYu,Xia, Sai,Jin, Jie Urban Science Institute 2019 도시과학 Vol.8 No.2

Hefei has suffered from heavy air pollution, especially car exhaust and industry emissions. The smoke contains PM2.5 and PM10. These smoke will enter people's bodies and have a bad impact on the human body. This review is about PM2.5. This review covers the sources and hazards of PM2.5. It introduces the use of modelling methods to analyze PM2.5 pollution in various places and proposes treatment measures. These cities were heavily polluted by PM2.5, and after the local government's management and renovation, there has been a significant improvement. However, there are still many shortcomings in the process of pollution improvement. This review combines the means used in the process of pollution prevention and control in Handan City, Beijing. Hefei now suffers from some of the same pollution as these cities did in the past.

A Novel Chemical Route to Atomic Layer Deposition of ZnS Thin Film from Diethylzinc and 1,5-Pentanedithiol

고동현,김성준,Zhenyu Jin,신석희,이선영,민요셉 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.7

This study describes a novel chemical route to grow ZnS thin films via atomic layer deposition (ALD). By using diethylzinc and 1,5-pentanedithiol as precursors of Zn and S, respectively, ZnS films are grown on substrates with an atomic precision by repeating self-limiting chemisorption of each precursor. The growth-per-cycle of the ALD process is around 0.1 Å per cycle at 150°C, and the as-grown films are characterized to be amorphous ZnS by X-ray diffraction and X-ray photoelectron spectroscopy.

Enhanced Morris for the extraction of significant parameters in high-dimensional design optimization

Pei Yuan,Jin Cheng,Zhenyu Liu,Daxin Liu,Jianrong Tan 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.11

The traditional Morris method cannot ensure the consistent extraction of significant parameters because its random sampling strategy often leads to an improper coverage of the input space, especially when the number of sample points is small. To overcome the drawbacks, we developed an improved sampling strategy to enhance the performance of Morris method based on Latin hypercube sampling (LHS) with the idea of Central composite design (CCD) and a fluctuant step to generate a more uniform points set. A comparison on the results of a numerical example obtained by the enhanced Morris, the traditional methods and CCS-Morris demonstrated that the former had a much better performance. The application of the enhanced Morris method in the high-dimensional optimization of a compressor shell with 15 design parameters aimed at increasing its natural frequencies and keeping its mass relatively light demonstrates that the method is effective and applicable in engineering design.

Band structure of amorphous zinc tin oxide thin films deposited by atomic layer deposition

이선영,김성준,신석희,Zhenyu Jin,민요셉 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.58 No.-

Recently, zinc tin oxide (ZTO) has attracted attention as an alternative buffer layer to replace CdS for photovoltaic cells. ZTO thin films were grown by atomic layer deposition from diethylzinc, tetrakis(dimethylamido)tin, and water. Compositional, structural and optical properties were characterized to construct band diagram of the ZTO films depending on Sn content. The ZTO films exhibit optical bandgaps of 2.95–3.07 eV which are wider than that of CdS. Furthermore, their work function is also observed to vary in a wide range of 4.32–5.16 eV. It is attributed to incorporation of Sn into ZTO which strongly influences formation of oxygen vacancies.