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138 results on '"Choi, Jong Hyun"'

2. Understanding the Effects of Dielectric Property, Separation Distance, and Band Alignment on Interlayer Excitons in 2D Hybrid MoS2/WSe2 Heterostructures

Author

Ji, Jaehoon and Choi, Jong Hyun

Subjects
Condensed Matter - Materials Science
Abstract

Two dimensional (2D) van der Waals heterostructures from transition metal dichalcogenide (TMDC) semiconductors show a new class of spatially separate excitons with extraordinary properties. The interlayer excitons (XI) have been studied extensively, yet the mechanisms that modulate XI are still not well understood. Here, we introduce several organic-layer-embedded hybrid heterostructures, MoS2/organic/WSe2, to study the binding energy of XI. We discover that the dielectric screening of the quasi-particle is reduced with organic molecules due to decreased dielectric constant and greater separation distance between the TMDC layers. As a result, a distinct blueshift is observed in interlayer emission. We also find that the band alignment at the heterointerface is critical. When the organic layer provides a staggered energy state, interlayer charge transfer can transition from tunneling to band-assisted transfer, further increasing XI emission energies due to a stronger dipolar interaction. The formation of XI may also be significantly suppressed with electron or hole trapping molecules. These findings should be useful in realizing XI-based optoelectronics.

Published
2020

7. Photoswitchable optoelectronic properties of 2D MoSe2/diarylethene hybrid structures.

Author

Park, Sewon, Ji, Jaehoon, Cunningham, Connor, Pillai, Srajan, Rouillon, Jean, Benitez-Martin, Carlos, Fang, Mengqi, Yang, Eui-Hyeok, Andréasson, Joakim, You, Jeong Ho, and Choi, Jong Hyun

Subjects
KELVIN probe force microscopy, FRONTIER orbitals, IRRADIATION, ATOMIC force microscopy, VISIBLE spectra, OPTICAL properties
Abstract

The ability to modulate optical and electrical properties of two-dimensional (2D) semiconductors has sparked considerable interest in transition metal dichalcogenides (TMDs). Herein, we introduce a facile strategy for modulating optoelectronic properties of monolayer MoSe2 with external light. Photochromic diarylethene (DAE) molecules formed a 2-nm-thick uniform layer on MoSe2, switching between its closed- and open-form isomers under UV and visible irradiation, respectively. We have discovered that the closed DAE conformation under UV has its lowest unoccupied molecular orbital energy level lower than the conduction band minimum of MoSe2, which facilitates photoinduced charge separation at the hybrid interface and quenches photoluminescence (PL) from monolayer flakes. In contrast, open isomers under visible light prevent photoexcited electron transfer from MoSe2 to DAE, thus retaining PL emission properties. Alternating UV and visible light repeatedly show a dynamic modulation of optoelectronic signatures of MoSe2. Conductive atomic force microscopy and Kelvin probe force microscopy also reveal an increase in conductivity and work function of MoSe2/DAE with photoswitched closed-form DAE. These results may open new opportunities for designing new phototransistors and other 2D optoelectronic devices. [ABSTRACT FROM AUTHOR]

Published
2024
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9. Effect of Anterioposterior Weight-Shift Training with Visual Biofeedback in Patients with Step Length Asymmetry after Subacute Stroke.

Author

Jo, Yea Jin, Kim, Dae Hyun, Kim, Seeun, Kim, Jung Hoon, Choi, Jong Hyun, Park, Jong Bum, Baek, Yoon Su, Park, Yoon Ghil, and Kim, Deog Young

Subjects
VISUAL training, STROKE, BIOFEEDBACK training, GAIT in humans, STROKE patients
Abstract

Step length asymmetry is a characteristic feature of gait in post-stroke patients. A novel anterioposterior weight-shift training method with visual biofeedback (AP training) was developed to improve the forward progression of the trunk. This study aimed to investigate the effect of AP training on gait asymmetries, patterns, and gait-related function in subacute stroke patients. Forty-six subacute stroke patients were randomly assigned to the AP training group or the control group. The AP training group received conventional gait training and AP training five times per week for 4 weeks. The control group received the same intensity of conventional gait training with patient education for self-anterior weight shifting. Plantar pressure analysis, gait analysis, energy consumption, and gait-related behavioral parameters were assessed before and after training. The AP training group showed significant improvement in step length asymmetry, forefoot contact area and pressure, Berg balance scale score, and Fugl-Meyer assessment scale of lower extremity score compared to the control group (p < 0.05). However, there was no significant between-group difference with respect to energy cost and kinetic and kinematic gait parameters. In conclusion, AP training may help improve the asymmetric step length in stroke patients, and also improve anterior weight shifting, balance, and motor function in subacute stroke survivors. [ABSTRACT FROM AUTHOR]

Published
2023
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15. Perovskite nickelates as bio-electronic interfaces

Author

Zhang, Hai-Tian, Zuo, Fan, Li, Feiran, Chan, Henry, Wu, Qiuyu, Zhang, Zhan, Narayanan, Badri, Ramadoss, Koushik, Chakraborty, Indranil, Saha, Gobinda, Kamath, Ganesh, Roy, Kaushik, Zhou, Hua, Chubykin, Alexander A., Sankaranarayanan, Subramanian K. R. S., Choi, Jong Hyun, and Ramanathan, Shriram

Published
2019
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16. Racial Disparities in Perioperative Morbidity Following Oncological Spine Surgery.

Author

De la Garza Ramos, Rafael, Choi, Jong Hyun, Naidu, Ishan, Benton, Joshua A., Echt, Murray, Yanamadala, Vijay, Passias, Peter G., Shin, John H., Altschul, David J., Goodwin, C. Rory, Sciubba, Daniel M., and Yassari, Reza

Subjects
ONCOLOGIC surgery, RACIAL inequality, SPINAL surgery, BLACK people, RACE, TUMOR surgery
Abstract

Study Design: Retrospective cohort study. Objective: To assess the impact of race on complications following spinal tumor surgery. Methods: Adults with cancer who underwent spine tumor surgery were identified in the American College of Surgeons National Surgical Quality Improvement Program datasets from 2012 to 2016. Clavien-Dindo Grade I-II (minor complications) and Clavien-Dindo Grade III-V (major complications including 30-day mortality) complications were compared between non-Hispanic Whites (NHW) and Black patients. A multivariable analysis was also conducted. Results: Of 1,226 identified patients, 85.9% were NHW (n = 1,053) and 14.1% were Black (n = 173). The overall rate of Grade I-II complications was 16.2%; 15.1% for NHW patients and 23.1% for Black patients (P =.008). On multivariable analysis, Black patients had significantly higher odds of having a minor complication (OR 1.87; 95% CI, 1.16-3.01; P =.010). On the other hand, the overall rate of Grade III-V complications was 13.3%; 12.5% for NHW patients and 16.2% for Black patients (P =.187). On multivariable analysis, Black race was not independently associated with major complications (OR 1.26; 95% CI, 0.71-2.23; P =.430). Median length of stay was 8 days (IQR 5-13) for NHW patients and 10 days (IQR 6-15) for Black patients (P =.011). Conclusion: Black patients who underwent metastatic spinal tumor surgery were at a significantly increased risk of perioperative morbidity compared to NHW patients independent of baseline and operative characteristics. Major complications did not differ between groups. Race should be further studied in the context of metastatic spine disease to improve our understanding of these disparities. [ABSTRACT FROM AUTHOR]

Published
2023
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18. 7 S ,15 R -Dihydroxy-16 S ,17 S -epoxy-docosapentaenoic Acid Overcomes Chemoresistance of 5-Fluorouracil by Suppressing the Infiltration of Tumor-Associated Macrophages and Inhibiting the Activation of Cancer Stem Cells in a Colorectal Cancer Xenograft Model

Author

Su, Yan, Choi, Hack Sun, Choi, Jong Hyun, Kim, Hee-Sik, Jang, Yong-Suk, and Seo, Jeong-Woo

Abstract

Although the tumor bulk is initially reduced by 5-fluorouracil (5-FU), chemoresistance developed due to prolonged chemotherapy in colorectal cancer (CRC). The enrichment of cancer stem cells (CSCs) and the infiltration of tumor-associated macrophages (TAMs) contribute to chemoresistance and poor outcomes. A docosahexaenoic acid derivative developed by our group, 7S,15R-dihydroxy-16S,17S-epoxy-docosapentaenoic acid (diHEP-DPA), exerts antitumor effects against TAMs infiltration and CSCs enrichment in our previous study. The current study aimed to investigate whether diHEP-DPA was able to overcome chemoresistance to 5-FU in CRCs, together with the potential synergistic mechanisms in a CT26-BALB/c mouse model. Our results suggested that although 5-FU inhibited tumor growth, 5-FU enriched CSCs via the WNT/β-catenin signaling pathway, resulting in chemoresistance in CRCs. However, we revealed that 5-FU promoted the infiltration of TAMs via the NF-kB signaling pathway and improved epithelial–mesenchymal transition (EMT) via the signal transducer and activator of the transcription 3 (STAT3) signaling pathway; these traits were believed to contribute to CSC activation. Furthermore, supplementation with diHEP-DPA could overcome drug resistance by decreasing the CSCs, suppressing the infiltration of TAMs, and inhibiting EMT progression. Additionally, the combinatorial treatment of diHEP-DPA and 5-FU effectively enhanced phagocytosis by blocking the CD47/signal regulatory protein alpha (SIRPα) axis. These findings present that diHEP-DPA is a potential therapeutic supplement to improve drug outcomes and suppress chemoresistance associated with the current 5-FU-based therapies for colorectal cancer. [ABSTRACT FROM AUTHOR]

Published
2023
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22. Racial Disparities in Perioperative Morbidity Following Oncological Spine Surgery

Author

De la Garza Ramos, Rafael, primary, Choi, Jong Hyun, additional, Naidu, Ishan, additional, Benton, Joshua A., additional, Echt, Murray, additional, Yanamadala, Vijay, additional, Passias, Peter G., additional, Shin, John H., additional, Altschul, David J., additional, Goodwin, C. Rory, additional, Sciubba, Daniel M., additional, and Yassari, Reza, additional

Published
2021
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24. Supplemental Material, sj-docx-1-gsj-10.1177_21925682211022290 - Racial Disparities in Perioperative Morbidity Following Oncological Spine Surgery

Author

De la Garza Ramos, Rafael, Choi, Jong Hyun, Naidu, Ishan, Benton, Joshua A., Echt, Murray, Yanamadala, Vijay, Passias, Peter G., Shin, John H., Altschul, David J., Goodwin, C. Rory, Sciubba, Daniel M., and Yassari, Reza

Subjects
FOS: Clinical medicine, 110323 Surgery, 110604 Sports Medicine, FOS: Health sciences, 110904 Neurology and Neuromuscular Diseases, 110314 Orthopaedics
Abstract

Supplemental Material, sj-docx-1-gsj-10.1177_21925682211022290 for Racial Disparities in Perioperative Morbidity Following Oncological Spine Surgery by Rafael De la Garza Ramos, Jong Hyun Choi, Ishan Naidu, Joshua A. Benton, Murray Echt, Vijay Yanamadala, Peter G. Passias, John H. Shin, David J. Altschul, C. Rory Goodwin, Daniel M. Sciubba and Reza Yassari in Global Spine Journal

Published
2021
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27. Clinical outcomes of endovascular treatment for ruptured thoracic aortic disease

Author

Choi, Jong Hyun, primary, Kim, Sang-Pil, additional, Lee, Han Cheol, additional, Park, Tae Sik, additional, Park, Jong Ha, additional, Kim, Bo Won, additional, Ahn, Jinhee, additional, Park, Jin Sup, additional, Lee, Hye Won, additional, Oh, Jun-Hyok, additional, Choi, Jung Hyun, additional, Cha, Kwang Soo, additional, and Hong, Taek Jong, additional

Published
2021
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29. Challenge for Diagnostic Assessment of Deep Learning Algorithm for Metastases Classification in Sentinel Lymph Nodes on Frozen Tissue Section Digital Slides in Women with Breast Cancer

Author

Kim, Young-Gon, primary, Song, In Hye, additional, Lee, Hyunna, additional, Kim, Sungchul, additional, Yang, Dong Hyun, additional, Kim, Namkug, additional, Shin, Dongho, additional, Yoo, Yeonsoo, additional, Lee, Kyowoon, additional, Kim, Dahye, additional, Jung, Hwejin, additional, Cho, Hyunbin, additional, Lee, Hyungyu, additional, Kim, Taeu, additional, Choi, Jong Hyun, additional, Seo, Changwon, additional, Han, Seong il, additional, Lee, Young Je, additional, Lee, Young Seo, additional, Yoo, Hyung-Ryun, additional, Lee, Yongju, additional, Park, Jeong Hwan, additional, Oh, Sohee, additional, and Gong, Gyungyub, additional

Published
2020
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31. DNA and Depletant Based Control of the Collective Motion of Gliding Microtubules

Author

Conlisk, Caleb A., Li, Feiran, and Choi, Jong Hyun

Subjects
Microtubule gliding assay, nanotechnology, motor protein, depletion force, DNA
Abstract

Motor proteins, like kinesin, transport cargo within biological cells by transforming chemical energy into mechanical energy through the hydrolysis of adenosine triphosphate (ATP). Kinesins walk across small tracks called microtubules. Recent studies have found that these concepts can be applied in vitro by attaching the motors to a glass substrate, on which microtubules can then glide across. These systems could be useful for many applications, such as targeted drug delivery and efficient, easy medical diagnosis. However, the motion of traveling microtubules is randomly ordered, and methods for controlling it are often hard to implement and recreate. One promising approach is to use depletants, or unreactive macromolecules, that can align microtubules in the same direction by forcing them to move together. This study aims to improve control of microtubule collective motion by using DNA as a signal to increase the effect that depletants have on the microtubule system. This is done by attaching bulky DNA molecules to the filaments, thus increasing their volumes. By comparing the organization of the system before and after the modification of the microtubules, the effects can be analyzed at many concentrations. This study provides an assessment of the relationship between the use of altered microtubules and the concentration of depletants within a gliding assay to induce an ordered collective motion.

Published
2018

36. The Clinical Efficacy and Safety of Four-Weekly Docetaxel as First-Line Therapy in Elderly Lung Cancer Patients with Squamous Cell Carcinoma

Author

Choi, Jong Hyun, primary, Choi, Juwhan, additional, Chung, Sang Mi, additional, Oh, Jee Youn, additional, Lee, Young Seok, additional, Min, Kyung Hoon, additional, Hur, Gyu Young, additional, Shim, Jae Jeong, additional, Kang, Kyung Ho, additional, Lee, Hyun Kyung, additional, and Lee, Sung Yong, additional

Published
2019
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37. Construction of a Vitreoscilla Hemoglobin Promoter-Based Tunable Expression System for Corynebacterium glutamicum

Author

Baritugo, Kei-Anne, primary, Kim, Hee Taek, additional, Rhie, Mi Na, additional, Jo, Seo Young, additional, Khang, Tae Uk, additional, Kang, Kyoung Hee, additional, Song, Bong Keun, additional, Lee, Binna, additional, Song, Jae Jun, additional, Choi, Jong Hyun, additional, Lee, Dae-Hee, additional, Joo, Jeong Chan, additional, and Park, Si Jae, additional

Published
2018
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40. Enhanced production of gamma-aminobutyrate (GABA) in recombinant Corynebacterium glutamicum strains from empty fruit bunch biosugar solution

Author

Baritugo, Kei-Anne, primary, Kim, Hee Taek, additional, David, Yokimiko, additional, Khang, Tae Uk, additional, Hyun, Sung Min, additional, Kang, Kyoung Hee, additional, Yu, Ju Hyun, additional, Choi, Jong Hyun, additional, Song, Jae Jun, additional, Joo, Jeong Chan, additional, and Park, Si Jae, additional

Published
2018
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43. Clinical and molecular characteristics of pulmonary sarcomatoid carcinoma

Author

Sim, Jae Kyeom, primary, Chung, Sang Mi, additional, Choi, Jong Hyun, additional, Oh, Jee Youn, additional, Lee, Seung Heon, additional, Kim, Je Hyeong, additional, Min, Kyung Hoon, additional, Hur, Gyu Young, additional, Shim, Jae Jeong, additional, Kang, Kyung Ho, additional, Shin, Bong Kyung, additional, Lee, Ju Han, additional, and Lee, Sung Yong, additional

Published
2018
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48. Porphyrin Interaction with DNA-Based Carbon Nanotubes and Regeneration for Light Harvesting

Author

Morgan, Sawyer E., Zhang, Hanyu, and Choi, Jong Hyun

Subjects
carbon nanotubes, Solar cell, chromophore, Other Mechanical Engineering, porphyrin
Abstract

Limitations to current solar cells include the high cost of pure silicon and poor current transfer within cells. An emerging alternative is single-walled carbon nanotubes (SWCNTs), which when combined with DNA and porphyrin chromophores can generate a current when absorbing light. We sought to find a chromophore and conditions that would promote bonding to the SWCNTs and improve light harvesting, while being able to regenerate on the film after being damaged. This was experimentally tested by first making SWCNT films on conducting glass slides. These were then functionalized in solutions of chromophore and spectra were measured to determine the bonding and absorbtion changes. Samples were also tested on an electrode system to measure photocurrents. Key shifts were noted for functionalization in porphyrin and defunctionalization in buffer solution, which caused the release of chromophore by DNA conformation change. The films consistently generated an electric current when exposed to light, with increased current from assembled SWCNT-DNA-porphyrin complexes. Through this testing we found that the regeneration was feasible with the solutions tested on the SWNT films and chromophore solutions. Further research can be done regarding DNA bonding interactions with porphryin and SWCNTs to promote functionality of the light-harvesting donor-acceptor complex.

Published
2014

49. Functionalization and Length Fractionation of Single-Wall Carbon Nanotubes

Author

Bragg, Nina A, Pan, Jing, and Choi, Jong Hyun

Subjects
lipids, carbon nanotubes, pyrene, surface chemistry, DNA, Nanoscience and Nanotechnology
Abstract

Single-wall carbon nanotubes (SWCNTs) are a promising material for future biological applications such as imaging and targeted drug delivery. SWCNTs can be made soluble in water through surface functionalization, a priority for their use in biology. By studying the surface chemistry of SWCNTs, various functionalization methods can be accomplished without perturbing their electronic structure. This study probes the use of pyrene derivatives and phospholipids to non-covalently functionalize SWCNTs, maintaining useful surface properties. Phospholipids cross-linked to polyethylene glycol (PEG) or 1-pyrenebutyric acid conjugated to DNA is anchored onto the sidewalls of SWCNTs by hydrophobic interactions or π-stacking. The PEG/DNA portion is water soluble and biocompatible, thus solubilizing the SWCNTs. Biofunctional materials such as DNA or proteins can be attached to the functionalized nanotubes and used for biological applications. Functionalization is characterized by optical methods and atomic force microscopy (AFM). Length sorting of SWCNTs fit for use in bio-functionalization is also explored. By functionalizing SWCNTs with groups that are cytologically compatible, allowing for their dispersion in water, they show greater promise in future biological applications.

Published
2014

50. The impact of transferring patients with ST-segment elevation myocardial infarction to percutaneous coronary intervention-capable hospitals on clinical outcomes

Author

Kim, Bo Won, primary, Cha, Kwang Soo, additional, Park, Min Joung, additional, Choi, Jong Hyun, additional, Yun, Eun Young, additional, Park, Jin Sup, additional, Lee, Hye Won, additional, Oh, Jun-Hyok, additional, Kim, Jeong Su, additional, Choi, Jung Hyun, additional, Park, Young Hyun, additional, Lee, Han Cheol, additional, Kim, June Hong, additional, Chun, Kook Jin, additional, Hong, Taek Jong, additional, Ahn, Youngkeun, additional, and Jeong, Myung Ho, additional

Published
2016
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