Visualizing Point Defects in Transition-Metal Dichalcogenides Using Optical Microscopy

Jeong, Hye Yun,Lee, Si Young,Ly, Thuc Hue,Han, Gang Hee,Kim, Hyun,Nam, Honggi,Jiong, Zhao,Shin, Bong Gyu,Yun, Seok Joon,Kim, Jaesu,Kim, Un Jeong,Hwang, Sungwoo,Lee, Young Hee American Chemical Society 2016 ACS NANO Vol.10 No.1

<P>While transmission electron microscopy and scanning tunneling microscopy reveal atomic structures of point defect and grain boundary in monolayer transition metal dichalcogenides (TMDs), information on point defect distribution in macroscale is still not available. Herein, we visualize the point defect distribution of monolayer TMDs using dark-field optical microscopy. This was realized by anchoring silver nanoparticles on defect sites of MoS2 under light illumination. The optical images clearly revealed that the point defect distribution varies with light power and exposure time. The number of silver nanoparticles increased initially and reached a plateau in response to light power or exposure time. The size of silver nanoparticles was a few hundred nanometers in the plateau region as observed using optical microscopy. The measured defect density in macroscale was similar to 2 x 10(10) cm(-2), slightly lower than the observed value (4 x 10(11) cm(-2)) from scanning tunneling microscopy.</P>

Successful pregnancy following transmyometrial embryo transfer after robot-assisted radical trachelectomy

Hye Jeong Hue,Hyun Ji Choi,Jee Yoon Park,Dong Hoon Suh,Lee Jung-Ryeol,Jee Byung Chul,Seul Ki Kim 대한생식의학회 2021 Clinical and Experimental Reproductive Medicine Vol.48 No.2

Radical trachelectomy is a fertility-preserving alternative to radical hysterectomy in carefully selected young women with early-stage cervical cancer. However, in cases with subsequent severe cervical stenosis, assisted reproductive techniques can be difficult. This is a case report of a 34-year-old patient who underwent robot-assisted radical trachelectomy and cerclage for early-stage (IB2) adenosquamous carcinoma. Three months after surgery, the patient underwent ovarian stimulation using a gonadotropin-releasing hormone antagonist protocol. As it was impossible to perform transcervical embryo transfer due to the almost complete absence of the cervical opening, transmyometrial embryo transfer under ultrasound guidance was performed. This resulted in a successful singleton pregnancy. This is the first case of successful pregnancy conceived by in vitro fertilization with transmyometrial embryo transfer in a patient who had previously undergone robot-assisted radical trachele Radical trachelectomy is a fertility-preserving alternative to radical hysterectomy in carefully selected young women with early-stage cervical cancer. However, in cases with subsequent severe cervical stenosis, assisted reproductive techniques can be difficult. This is a case report of a 34-year-old patient who underwent robot-assisted radical trachelectomy and cerclage for early-stage (IB2) adenosquamous carcinoma. Three months after surgery, the patient underwent ovarian stimulation using a gonadotropin-releasing hormone antagonist protocol. As it was impossible to perform transcervical embryo transfer due to the almost complete absence of the cervical opening, transmyometrial embryo transfer under ultrasound guidance was performed. This resulted in a successful singleton pregnancy. This is the first case of successful pregnancy conceived by in vitro fertilization with transmyometrial embryo transfer in a patient who had previously undergone robot-assisted radical trachelectomy.

Optical Gain in MoS₂ <i>via</i> Coupling with Nanostructured Substrate: Fabry–Perot Interference and Plasmonic Excitation

Jeong, Hye Yun,Kim, Un Jeong,Kim, Hyun,Han, Gang Hee,Lee, Hyangsook,Kim, Min Su,Jin, Youngjo,Ly, Thuc Hue,Lee, Si Young,Roh, Young-Geun,Joo, Won-Jae,Hwang, Sung Woo,Park, Yeonsang,Lee, Young Hee American Chemical Society 2016 ACS NANO Vol.10 No.9

<P>Despite the direct band gap of monolayer transition metal dichalcogenides (TMDs), their optical gain remains limited because of the poor light absorption in atomically thin, layered materials. Most approaches to improve the optical gain of TMDs mainly involve modulation of the active materials or multilayer stacking. Here, we report a method to enhance the optical absorption and emission in MoS2 simply through the design of a nanostructured substrate. The substrate consisted of a dielectric nanofilm spacer (TiO2) and metal film. The overall photoluminescence intensity from monolayer MoS2 on the nanostructured substrate was engineered based on the TiO2 thickness and amplified by Fabry-Perot interference. In addition, the neutral exciton emission was selectively amplified by plasmonic excitations from the local field originating from the surface roughness of the metal film with spacer thicknesses of less than 10 nm. We further demonstrate that the quality factor of the device can also be engineered by selecting a spacer material with a different refractive index.</P>

Prevalence and confounders of chronic endometritis diagnosed using CD138 in patients with recurrent implantation failure

Hue Hye Jeong,최현지,이현경,이정렬,지병철,주창우,김슬기 대한생식의학회 2024 Clinical and Experimental Reproductive Medicine Vol.51 No.2

Objective: This retrospective study aimed to investigate the prevalence of chronic endometritis, diagnosed using CD138 immunohistochemistry, among infertile women and to assess the association between chronic endometritis and recurrent implantation failure (RIF).Methods: In total, 266 patients who underwent hysteroscopy due to infertility between 2019 and 2020 were included in the analysis. Of these, 136 patients with RIF and 130 non-RIF patients were included in the study. CD138 immunohistochemistry test results, blood biomarkers (including natural killer cells, white blood cells, and the lymphocyte-to-neutrophil ratio), and data on pregnancy outcomes were obtained. If the CD138 test yielded a positive result, the patients received antibiotic treatment.Results: The overall proportion of CD138-positive patients was 32.7% (87/266). The CD138 positivity rate was not related to the number of cycles with implantation failure. In the RIF patient group, no significant associations were found between CD138 positivity and peripheral blood markers. The clinical pregnancy rates were similar between infertile women treated with antibiotics for chronic endometritis and those without chronic endometritis.Conclusion: To improve the pregnancy rate in infertile patients, it may be helpful to combine CD138 testing with other laboratory tests and administer antibiotic treatment if the result is positive.

Observing Grain Boundaries in CVD-Grown Monolayer Transition Metal Dichalcogenides

Ly, Thuc Hue,Chiu, Ming-Hui,Li, Ming-Yang,Zhao, Jiong,Perello, David J.,Cichocka, Magdalena Ola,Oh, Hye Min,Chae, Sang Hoon,Jeong, Hye Yun,Yao, Fei,Li, Lain-Jong,Lee, Young Hee American Chemical Society 2014 ACS NANO Vol.8 No.11

<P>Two-dimensional monolayer transition metal dichalcogenides (TMdCs), driven by graphene science, revisit optical and electronic properties, which are markedly different from bulk characteristics. These properties are easily modified due to accessibility of all the atoms viable to ambient gases, and therefore, there is no guarantee that impurities and defects such as vacancies, grain boundaries, and wrinkles behave as those of ideal bulk. On the other hand, this could be advantageous in engineering such defects. Here, we report a method of observing grain boundary distribution of monolayer TMdCs by a selective oxidation. This was implemented by exposing directly the TMdC layer grown on sapphire without transfer to ultraviolet light irradiation under moisture-rich conditions. The generated oxygen and hydroxyl radicals selectively functionalized defective grain boundaries in TMdCs to provoke morphological changes at the boundary, where the grain boundary distribution was observed by atomic force microscopy and scanning electron microscopy. This paves the way toward the investigation of transport properties engineered by defects and grain boundaries.</P>

Nondestructive Characterization of Graphene Defects

Ly, Thuc Hue,Duong, Dinh Loc,Ta, Quang Huy,Yao, Fei,Vu, Quoc An,Jeong, Hye Yun,Chae, Sang Hoon,Lee, Young Hee WILEY‐VCH Verlag 2013 Advanced functional materials Vol.23 No.41

<P><B>Abstract</B></P><P>An effective method is reported for oxidizing graphene/copper film in which air oxidation of the underlying copper film occurs through the grain boundary lines of graphene without oxidizing graphene. This oxidation is realized by partially immersing the graphene/copper film in sodium chloride solution. Electrons generated during etching of the graphene/copper film in electrolyte diffuse into the film in contact with air, which eventually enhances air oxidation of copper through the graphene layer. While the graphene layer acts as a protective layer against oxidation of the copper film, oxidation of the underlying Cu film near graphene grain boundary lines is observed by optical microscopy. This observation could be attributed to the selective diffusion of oxygen radicals through isolated defects and graphene grain boundaries. The process involves no appreciable oxidation of the graphene layer including the graphene grain boundary, as confirmed by use of detailed Raman and X‐ray photoelectron spectroscopy.</P>

Successful pregnancy following transmyometrial embryo transfer after robot-assisted radical trachelectomy

( Hyun Ji Choi ),( Hye Jeong Hue ),( Jee Yoon Park ),( Seul Ki Kim ),( Dong Hoon Suh ),( Jung Ryeol Lee ),( Byung Chul Jee ) 대한산부인과학회 2020 대한산부인과학회 학술대회 Vol.106 No.-

Radical trachelectomy in women with early-stage cervical cancer is a fertility-preserving alternative to radical hysterectomy in well-selected young patients. However, it presents a great challenge for assisted reproductive techniques in cases with subsequent severe cervical stenosis. This is a report of a 34-year-old patient who underwent robot-assisted radical trachelectomy and cerclage for early-stage (IB2) adenosquamous carcinoma. Three months after the surgery, the patient underwent ovarian stimulation using a GnRH antagonist protocol. As it was impossible to perform transcervical embryo transfer with an almost absent cervical opening, a transmyometrial embryo transfer under ultrasound guidance was performed. This resulted in a successful singleton pregnancy. This is the first case of successful pregnancy conceived by IVF with transmyometrial embryo transfer for a patient who had previously undergone robot-assisted radical trachelectomy.

The clinical value of fetal fibronectin for preterm birth in symptomatic uterine contractions in twin pregnant women

( Ji Hoi Kim ),( Seung Mi Lee ),( So Yeon Kim ),( Hye Jeong Hue ),( Chan-wook Park ),( Joong Shin Park ),( Jong Kwan Jun ) 대한산부인과학회 2019 대한산부인과학회 학술대회 Vol.105 No.-

Objective: Accurate prediction of impending preterm birth in twin pregnancy is an important issue in the clinical decision for administration of antenatal corticosteroid or tocolytics and transfer to referral hospitals. Ultrasound cervical length(CL) measurement and fetal fibronectin(fFN) test is the most effective tools in predicting the risk of preterm delivery for asymptomatic twin pregnancies. The objective of this study was to evaluate the clinical value of fFN for prediction of preterm birth in symptomatic twin pregnancies. Methods: The study population consisted of twin pregnant women who had symptomatic preterm uterine contractions without evidences of ruptured membranes at <34 weeks. At the time of visit, fFN was tested. The clinical characteristics and the risk of preterm birth (< 7 and 14 days of visit and preterm delivery of < 34 and 37 weeks of gestation) was compared according to the result of fFN. Results: Between 2013 and 2018, total of 104 twin pregnant women visited our institution with preterm uterine contractions at <34 weeks of gestation. Among the study population, 50 women (48%) showed positive result for fFN. Positive fFN group had shorter cervical length and had higher risk for preterm birth (<7 days, <14 days, < 34 weeks, and <37weeks). The risk of preterm birth within 7 days of visit remained significant after adjustment for cervical length. Conclusion: In twin pregnant women with symptomatic uterine contractions, positive fFN may be used for prediction of preterm birth.

Transferred wrinkled Al₂O₃ for highly stretchable and transparent graphene–carbon nanotube transistors

Chae, Sang Hoon,Yu, Woo Jong,Bae, Jung Jun,Duong, Dinh Loc,Perello, David,Jeong, Hye Yun,Ta, Quang Huy,Ly, Thuc Hue,Vu, Quoc An,Yun, Minhee,Duan, Xiangfeng,Lee, Young Hee Nature Publishing Group 2013 Nature materials Vol.12 No.5

Despite recent progress in producing transparent and bendable thin-film transistors using graphene and carbon nanotubes, the development of stretchable devices remains limited either by fragile inorganic oxides or polymer dielectrics with high leakage current. Here we report the fabrication of highly stretchable and transparent field-effect transistors combining graphene/single-walled carbon nanotube (SWCNT) electrodes and a SWCNT-network channel with a geometrically wrinkled inorganic dielectric layer. The wrinkled Al<SUB>2</SUB>O<SUB>3</SUB> layer contained effective built-in air gaps with a small gate leakage current of 10<SUP>−13</SUP> A. The resulting devices exhibited an excellent on/off ratio of ~10<SUP>5</SUP>, a high mobility of ~40 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> and a low operating voltage of less than 1 V. Importantly, because of the wrinkled dielectric layer, the transistors retained performance under strains as high as 20% without appreciable leakage current increases or physical degradation. No significant performance loss was observed after stretching and releasing the devices for over 1,000 times. The sustainability and performance advances demonstrated here are promising for the adoption of stretchable electronics in a wide variety of future applications.

Role of alkali metal promoter in enhancing lateral growth of monolayer transition metal dichalcogenides

Kim, Hyun,Han, Gang Hee,Yun, Seok Joon,Zhao, Jiong,Keum, Dong Hoon,Jeong, Hye Yun,Ly, Thuc Hue,Jin, Youngjo,Park, Ji-Hoon,Moon, Byoung Hee,Kim, Sung-Wng,Lee, Young Hee IOP 2017 Nanotechnology Vol.28 No.36

<P>Synthesis of monolayer transition metal dichalcogenides (TMDs) via chemical vapor deposition relies on several factors such as precursor, promoter, substrate, and surface treatment of substrate. Among them, the use of promoter is crucial for obtaining uniform and large-area monolayer TMDs. Although promoters have been speculated to enhance adhesion of precursors to the substrate, their precise role in the growth mechanism has rarely been discussed. Here, we report the role of alkali metal promoter in growing monolayer TMDs. The growth occurred via the formation of sodium metal oxides which prevent the evaporation of metal precursor. Furthermore, the silicon oxide substrate helped to decrease the Gibbs free energy by forming sodium silicon oxide compounds. The resulting sodium metal oxide was anchored within such concavities created by corrosion of silicon oxide. Consequently, the wettability of the precursors to silicon oxide was improved, leading to enhance lateral growth of monolayer TMDs.</P>