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Reference Electrode at Molten Salt: A Comparative Analysis of Electroceramic Membranes
Yoon, Seokjoo,Kang, Dokyu,Sohn, Sungjune,Park, Jaeyeong,Lee, Minho,Choi, Sungyeol Korean Radioactive Waste Society 2020 방사성폐기물학회지 Vol.18 No.2
A reference electrode is important for controlling electrochemical reactions. Evaluating properties such as the reduction potential of the elements is necessary to optimize the electrochemical processes in pyroprocessing, especially in a multicomponent environment. In molten chloride systems, which are widely used in pyroprocessing, a reference electrode is made by enclosing the silver wire and molten salt solution containing silver chloride into the membranes. However, owing to the high temperature of the molten salt, the choice of the membrane for the reference electrode is limited. In this study, three types of electroceramic, mullite, Pyrex, and quartz, were compared as reference electrode membranes. They are widely used in molten salt electrochemical processes. The potential measurements between the two reference electrode systems showed that the mullite membrane has potential deviations of approximately 50 mV or less at temperatures higher than 650℃, Pyrex at temperatures lower than 500℃, and quartz at temperatures higher than 800℃. Cyclic voltammograms with different membranes showed a significant potential shift when different membranes were utilized. This research demonstrated the uncertainties of potential measurement by a single membrane and the potential shift that occurs because of the use of different membranes.
Origin of Shape-Dependent Fluorescence Polarization from CdSe Nanoplatelets
Yoon, Da-Eun,Kim, Whi Dong,Kim, Dahin,Lee, Dongkyu,Koh, Sungjun,Bae, Wan Ki,Lee, Doh C. American Chemical Society 2017 The Journal of Physical Chemistry Part C Vol.121 No.44
<P>In this study, we report the shape dependence of fluorescence polarization from colloidal CdSe nanoplatelets (NPLs). Despite the symmetry of their cubic unit cell structure, CdSe nanocrystals grow into two-dimensional platelets in the presence of acetate precursors, and the resulting NPLs exhibit polarized emission. The amount of acetate salts introduced during the synthesis plays a critical role in controlling the lateral aspect ratio of CdSe NPLs. Specifically, the more the acetate hydrate presents, the more squarelike face of NPLs emerges. As a result, we achieved CdSe NPLs with varying lateral aspect ratios ranging from 1.1 to 4.5 in our experimental conditions. At the same thickness, CdSe NPLs with higher lateral aspect ratios exhibit higher fluorescence polarization. We analyzed the shape dependence by preparing films of CdSe NPLs dropcast under an electric field and measuring emission and absorption polarizations from CdSe NPL films of known orientation parameters. The emission polarization stays nearly unchanged regardless of shape anisotropy of CdSe NPLs, while the absorption polarization is affected by the lateral aspect ratio. Now that these results allude to a likelihood that absorption polarization is responsible for the shape dependence of fluorescence polarization, we design a model to assess the correlation between the geometry of NPLs and the optical transition polarization by way of the local field effect. Theoretically estimated absorption polarization also shows shape dependence similar to experimental data, which suggests that the anisotropic local field effect is a primary denominator of shape-dependent fluorescence polarization in CdSe NPLs.</P>
( Sungjun Choi ),( Hyun-sun Yoon ) 대한피부과학회 2020 대한피부과학회 학술발표대회집 Vol.72 No.1
Background: Misclassification of study designs of journals can hinder the readers from assessing the strengths and weaknesses of the study and evaluating the applicability of the study in the real-world setting. However, it seems that it is common for authors to neglect to classify the study design. Objectives: We aimed to evaluate the accuracy of the classification of study designs and examine the common errors. Methods: Among Asian dermatology journals listed in the science citation index expanded from January 2018 to December 2018, we investigated discrepancies between author-reported and actual study designs. Design Algorithm for Medical Literature on Intervention (DAMI) was used to determine the actual study design. Results: Of the 177 papers analyzed, only 72 articles (40.7%) revealed their study design and among them, 23 articles (32.0%) showed discrepancies between the author-reported and the actual study designs. Case-control studies were the most commonly misclassified study designs by authors. Conclusion: There were considerable differences between the author-reported study design and the actual study design in Asian dermatology journals. Proper classification of study designs by the authors is essential to strengthen evidence-based medicine.
Yoon, Sungjun,Kim, Jeong Ah,Lee, Seung Hwan,Kim, Minsoo,Park, Tai Hyun Royal Society of Chemistry 2013 Lab on a chip Vol.13 No.8
<P>The importance of creating a three-dimensional (3-D) multicellular spheroid has recently been gaining attention due to the limitations of monolayer cell culture to precisely mimic in vivo structure and cellular interactions. Due to this emerging interest, researchers have utilized new tools, such as microfluidic devices, that allow high-throughput and precise size control to produce multicellular spheroids. We have developed a droplet-based microfluidic system that can encapsulate both cells and magnetic nanoparticles within alginate beads to mimic the function of a multicellular tumor spheroid. Cells were entrapped within the alginate beads along with magnetic nanoparticles, and the beads of a relatively uniform size (diameters of 85% of the beads were 170-190 μm) were formed in the oil phase. These beads were passed through parallel streamlines of oil and culture medium, where the beads were magnetically transferred into the medium phase from the oil phase using an external magnetic force. This microfluidic chip eliminates additional steps for collecting the spheroids from the oil phase and transferring them to culture medium. Ultimately, the overall spheroid formation process can be achieved on a single microchip.</P>
( Sungjun Choi Daein Choi ),( Seulggie Choi ),( Sang Min Park ),( Hyun-sun Yoon ) 대한피부과학회 2020 대한피부과학회 학술발표대회집 Vol.72 No.1
Background: There is emerging evidence that rosacea is associated with various systemic diseases. However, its association with cardiovascular disease (CVD) remains controversial. Objectives: We aimed to investigate whether patients with rosacea are at increased risk of developing CVD. Methods: This retrospective cohort study from the Korean National Health Insurance Service-Health Screening Cohort included patients with newly diagnosed rosacea (n=2,681) and age-, sex-, and index year-matched controls without rosacea (n=26,810) between 2003 and 2014. The primary outcome was subsequent CVD including coronary heart disease and stroke. Multivariable Cox regression analyses were used to evaluate adjusted hazard ratios (aHRs) for subsequent CVD adjusted for major risk factors of CVD. Results: Compared to controls, patients with rosacea were more likely to have more comorbidities and were less likely to smoke, consume alcohol, and exercise regularly. Rosacea patients displayed an increased risk for CVD (aHR 1.20, 95% CI 1.03-1.40) and coronary heart disease (aHR 1.29, 95% CI 1.05-1.60) compared to controls. The risk for stroke was not significantly increased (aHR 1.12, 95% CI 0.91-1.37). Conclusion: Patients with rosacea are more likely to develop subsequent CVD adjusted for major CVD risk factors.
( Sungjun Choi ),( Hyun-sun Yoon ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.2
Background: It is sometimes difficult to discriminate verruca plana (VP) from seborrheic keratosis (SK) presenting multiple and tiny papules (VP-like SK). As VP and SK have different treatment strategies and prognoses, differentiation between VP and VP-like SK is important. Objectives: The objective of this study was to elucidate the clinicopathological differential characteristics between VP and VP-like SK and investigate the predictors associated with the treatment outcomes of VP. Methods: We retrospectively investigated patients who underwent skin biopsy for differentiating between VP and VP-like SK from 2013 to 2019. Results: Among 145 identified cases, 59.3% (n=86) had VP, and 40.7% (n=59) had VP-like SK. We revealed that the patients with VP were more likely to have skin-colored or pink and confluently distributed lesions larger than 3 mm and located on the extremities than those with VP-like SK. The predictors associated with the treatment success of VP were the presence of skin-colored or pink lesions and those located on the upper extremities and treatment with systemic retinoid combined with diphenylcyclopropenone or carbon dioxide laser. Conclusion: Our study proposed useful differential characteristics between VP and VP-like SK in a large number of biopsy-proven cases and strengthened proper management strategies for VP.