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Millimeter-Scale Growth of Single-Oriented Graphene on a Palladium Silicide Amorphous Film
Kim, Hyun-Woo,Song, Inkyung,Kim, Tae-Hoon,Ahn, Sung Joon,Shin, Ha-Chul,An, Byeong-Seon,Jang, Yamujin,Jeon, Sunam,Kim, Eun Hye,Khadka, Ishwor Bahadur,Gu, TaeJun,Woo, Sun-Hee,Whang, Dongmok,Kim, Youngku American Chemical Society 2019 ACS NANO Vol.13 No.2
<P>It is widely accepted in condensed matter physics and material science communities that a single-oriented overlayer cannot be grown on an amorphous substrate because the disordered substrate randomizes the orientation of the seeds, leading to polycrystalline grains. In the case of two-dimensional materials such as graphene, the large-scale growth of single-oriented materials on an amorphous substrate has remained unsolved. Here, we demonstrate experimentally that the presence of uniformly oriented graphene seeds facilitates the growth of millimeter-scale single-oriented graphene with 3 × 4 mm<SUP>2</SUP> on palladium silicide, which is an amorphous thin film, where the uniformly oriented graphene seeds were epitaxially grown. The amorphous palladium silicide film promotes the growth of the single-oriented growth of graphene by causing carbon atoms to be diffusive and mobile within and on the substrate. In contrast to these results, without the uniformly oriented seeds, the amorphous substrate leads to the growth of polycrystalline graphene grains. This millimeter-scale single-oriented growth from uniformly oriented seeds can be applied to other amorphous substrates.</P> [FIG OMISSION]</BR>
Gradient index lens based combined two-photon microscopy and optical coherence tomography
Wang, Taejun,Li, Qingyun,Xiao, Peng,Ahn, Jinhyo,Kim, Young Eun,Park, Youngrong,Kim, Minjun,Song, Miyeoun,Chung, Euiheon,Chung, Wan Kyun,Ahn, G-One,Kim, Sungjee,Kim, Pilhan,Myung, Seung-Jae,Kim, Ki Hea The Optical Society 2014 Optics express Vol.22 No.11
Park Sang Won,Yeo Na Young,Kang Seonguk,Ha Taejun,Kim Tae-Hoon,Lee DooHee,Kim Dowon,Choi Seheon,Kim Minkyu,Lee DongHoon,Kim DoHyeon,Kim Woo Jin,Lee Seung-Joon,Heo Yeon-Jeong,Moon Da Hye,Han Seon-Sook 대한의학회 2024 Journal of Korean medical science Vol.39 No.5
Background: Worldwide, sepsis is the leading cause of death in hospitals. If mortality rates in patients with sepsis can be predicted early, medical resources can be allocated efficiently. We constructed machine learning (ML) models to predict the mortality of patients with sepsis in a hospital emergency department. Methods: This study prospectively collected nationwide data from an ongoing multicenter cohort of patients with sepsis identified in the emergency department. Patients were enrolled from 19 hospitals between September 2019 and December 2020. For acquired data from 3,657 survivors and 1,455 deaths, six ML models (logistic regression, support vector machine, random forest, extreme gradient boosting [XGBoost], light gradient boosting machine, and categorical boosting [CatBoost]) were constructed using fivefold cross-validation to predict mortality. Through these models, 44 clinical variables measured on the day of admission were compared with six sequential organ failure assessment (SOFA) components (PaO2/FIO2 [PF], platelets (PLT), bilirubin, cardiovascular, Glasgow Coma Scale score, and creatinine). The confidence interval (CI) was obtained by performing 10,000 repeated measurements via random sampling of the test dataset. All results were explained and interpreted using Shapley’s additive explanations (SHAP). Results: Of the 5,112 participants, CatBoost exhibited the highest area under the curve (AUC) of 0.800 (95% CI, 0.756–0.840) using clinical variables. Using the SOFA components for the same patient, XGBoost exhibited the highest AUC of 0.678 (95% CI, 0.626–0.730). As interpreted by SHAP, albumin, lactate, blood urea nitrogen, and international normalization ratio were determined to significantly affect the results. Additionally, PF and PLTs in the SOFA component significantly influenced the prediction results. Conclusion: Newly established ML-based models achieved good prediction of mortality in patients with sepsis. Using several clinical variables acquired at the baseline can provide more accurate results for early predictions than using SOFA components. Additionally, the impact of each variable was identified.
Kim, TaeSoo,Kuwamura, Hitoshi,Cho, Taejun,Shin, SungWoo,Kim, SeungHun,Lee, YongTaeg The Iron and Steel Institute of Japan 2008 ISIJ international Vol.48 No.6
<P>A finite element (FE) analysis with three-dimensional solid elements has been performed for estimating the structural behaviors of single shear bolted connections fabricated with cold-formed austenitic stainless steel by utilizing the existing test data for calibration. Failure and curling (out-of-plane deformation perpendicular to the direction of loading) criteria were proposed. Therefore, the failure mode and ultimate strength, predicted by FE analysis method, showed good agreements with those of experimental results. In this study, FE analyses for 10 test specimens fabricated with cold-formed carbon steel as well as stainless steel including failure mode of bolt shear fracture are carried out and the validity of numerical prediction for ultimate behaviors in cold-formed carbon steel bolted connections is also verified, based on the applicability of FE method for predicting the mechanical behaviors of bolted connections in cold-formed stainless steel. It is known from the coupon test results of steel materials that austenitic stainless (SUS304) steel has a higher tensile strength of material due to the effect of strength enhancements (considerable strain hardening) by means of cold-working process and much lower yield stress when compared to carbon steel. The influence of curling on the strength reduction of bolted connections is estimated quantitatively. In addition, characteristics of mechanical behaviors and the influence of curling in bolted connections between two different steel materials are compared through detailed investigation of FE analysis results.</P>
Kim, Dokyoung,Moon, Hyunsoo,Baik, Sung Hoon,Singha, Subhankar,Jun, Yong Woong,Wang, Taejun,Kim, Ki Hean,Park, Byung Sun,Jung, Junyang,Mook-Jung, Inhee,Ahn, Kyo Han American Chemical Society 2015 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.137 No.21
<P>Fluorescence imaging of tissues offer an essential means for studying biological systems. Autofluorescence becomes a serious issue in tissue imaging under excitation at UV-vis wavelengths where biological molecules compete with the fluorophore. To address this critical issue, a novel class of fluorophores that can :be excited at, similar to 900 nm under two-photon excitation conditions and emits in the red wavelength region (>= 600 nm) has been disclosed. The new pi-extended dipolar dye system, shows several advantageous features including minimal antofluorescence in tissue imaging and pronounced solvent-sensitive emission behavior, compared with a widely used two-photon absorbing dye, acedan. As an important application of the new dye system, one of the dyes was developed into a fluorescent probe for amyloicl-beta plaques, a key biomarker of Alzheimer's disease. The probe enabled in Vivo imaging of amyloid-beta plaques in a disease-model mouse, with negligible background signal. The new dye system has great potential for the development of other types of two-photon fluorescent probes and tags for imaging of tissues with minimal autofluorescence.</P>