Crack prevention of biodegradable polymer coating on metal facilitated by a nano-coupled interlayer

Cho, Youngjin,Vu, Bach Quang,Bedair, Tarek M,Park, Bang Ju,Joung, Yoon Ki,Han, Dong Keun Technomic Pub. Co 2014 Journal of bioactive and compatible polymers Vol.29 No.5

<P>Crack prevention of biodegradable polymer coatings on drug-eluting stents was investigated by introducing a nano-coupled layer at the interface between the metal surface and the polymer coating layer using surface-initiated ring-opening polymerization of ε-caprolactone. Poly(<SMALL>d</SMALL>,<SMALL>l</SMALL>-lactide-co-glycolide) coating on cobalt-chromium control and ricinoleic acid-poly(caprolactone)–grafted cobalt-chromium was carried out using electrospraying. The cracking of the biodegradable polymer coating on drug-eluting stents during ballooning was addressed by introducing a nano-coupled interlayer on the cobalt-chromium surface. The ricinoleic acid-poly(caprolactone) nano-coupled interlayer and poly(<SMALL>d</SMALL>,<SMALL>l</SMALL>-lactide-co-glycolide)-coated top layer were characterized using attenuated total reflection Fourier transform infrared, contact angle, ellipsometry, X-ray photoelectron spectroscopy, and atomic force microscopy. Based on scratch tests, the nano-coupled samples had stronger interfacial adhesion compared to the control sample without the nano-coupled layer. Scanning electron microscope images indicated that the cracking on the poly(<SMALL>d</SMALL>,<SMALL>l</SMALL>-lactide-co-glycolide) coating was addressed. Introducing a nano-coupling interlayer may be an important strategy to preventing polymer coating cracking on drug-eluting stents.</P>

Effects of Low-Intensity Autonomic Nerve Stimulation on Atrial Electrophysiology

Cho, Youngjin,Cha, Myung-Jin,Choi, Eue-Keun,Oh, Il-Young,Oh, Seil The Korean Society of Cardiology 2014 Korean Circulation Journal Vol.44 No.4

<P><B>Background and Objectives</B></P><P>The cardiac autonomic nervous system is an emerging target for therapeutic control of atrial fibrillation (AF). We evaluated the effects of low-intensity autonomic nerve stimulation (LI-ANS) on atrial electrophysiology, AF vulnerability, and neural remodeling.</P><P><B>Subjects and Methods</B></P><P>Fourteen dogs were subjected to 3 hours rapid atrial pacing (RAP, 5 Hz) and concomitant high frequency LI-ANS (20 Hz, at voltages 40% below the threshold) as follows: no autonomic stimulation (control, n=3); or right cervical vagus nerve (RVN, n=6), anterior right ganglionated plexi (ARGP, n=3), and superior left ganglionated plexi (SLGP, n=2) stimulation. Programmed and burst atrial pacing were performed at baseline and at the end of each hour to determine atrial effective refractory period (ERP), window of vulnerability (WOV), and inducibility of sustained AF.</P><P><B>Results</B></P><P>Atrial ERP was significantly shortened by 3 hours RAP (in control group, ΔERP=-47.9±8.9%, p=0.032), and RAP-induced ERP shortening was attenuated by LI-ANS (in LI-ANS group, ΔERP=-15.4±5.9%, p=0.019; vs. control, p=0.035). Neither WOV for AF nor AF inducibility changed significantly during 3 hours RAP with simultaneous LI-ANS. There was no significant difference between the control and LI-ANS group in nerve density and sprouting evaluated by anti-tyrosine hydroxylase and anti-growth associated protein-43 staining. Among the various sites for LI-ANS, the ARGP-stimulation group showed marginally lower ΔWOV (p=0.077) and lower nerve sprouting (p=0.065) compared to the RVN-stimulation group.</P><P><B>Conclusion</B></P><P>Low-intensity autonomic nerve stimulation significantly attenuated the shortening of atrial ERP caused by RAP. ARGP may be a better target for LI-ANS than RVN for the purpose of suppressing atrial remodeling in AF.</P>

Posterior Body Surface Potential Mapping Using Capacitive-Coupled Electrodes and Its Application

Cho, Youngjin,Lee, Seungmin,Choi, Eue-Keun,Park, Hyo Eun,Park, Kwang-Suk,Oh, Seil The Korean Academy of Medical Sciences 2012 JOURNAL OF KOREAN MEDICAL SCIENCE Vol.27 No.12

<P>Using 49 capacitive-coupled electrodes, mattress-type harness was developed to obtain posterior body surface potential map (P-BSPM) in dressed individuals. The aim of this study was to investigate how valuable information P-BSPM could provide, especially in discrimination of old myocardial infarction (OMI). P-BSPM of 59 individuals were analyzed; 23 normal control, 11 right bundle branch block (RBBB), 3 left bundle branch block (LBBB) and 19 OMI patients. Principal component analysis and linear hyper-plane approach were used to evaluate diagnostic performance. The axes of P-BSPM vector potential corresponded well with 12-lead electrocardiogram. During QRS, the end point of P-BSPM vector potential demonstrated characteristic clockwise rotation in RBBB, and counterclockwise rotation in LBBB patients. In OMI, initial negativity on P-BSPM during QRS was more frequently located at lower half, and also stronger in patients with inferior myocardial infarction (MI). The area under the receiver-operating characteristic curve of P-BSPM during QRS in diagnosing overall OMI, anterior MI, and inferior MI was 0.83 (95% confidence interval, 0.70-0.97), 0.71 (0.47-0.94), and 0.98 (0.94-1.0), respectively (<I>P</I> = 0.022 for anterior vs inferior MI groups). In conclusion, the novel P-BSPM provides detailed information for cardiac electrical dynamics and is applicable to diagnosing OMI, especially inferior myocardial infarction.</P>

Analysis of Meteorological Service Requirements for Safe Operation of Low-altitude Aircraft

YoungJin Cho,SeokMin Hong,Sungkwan Ku 국제문화기술진흥원 2018 International Journal of Advanced Culture Technolo Vol.6 No.4

Meteorological information is essential for the safe operation of aircraft. Many organizations both at home and abroad provide meteorological services for small aircraft flying at a low altitude as a part of open public service and have performed relevant studies. Recently, such a service has been expanded to an online platform in order to deliver information more efficiently. The ultimate goal of this study is to improve the meteorological service for small low-altitude aircraft that mostly travel a short distance for a short time. To achieve this goal, this study considered requirements for developing an effective information delivery system and conducted a survey of user requirements to derive the necessary information that could be used to develop a real service.

Multivariate response regression with low-rank and generalized sparsity

Cho Youngjin,Park Seyoung 한국통계학회 2022 Journal of the Korean Statistical Society Vol.51 No.3

In this study, we propose a multivariate-response regression by imposing structural conditions on the underlying regression coefficient matrix motivated by an analysis of Cancer Cell Line Encyclopedia (CCLE) data consisting of resistance responses to multiple drugs and gene expression of cancer cell lines. It is important to estimate the drug resistance response from gene information and identify those genes responsible for the sensitivity of the resistance response to each drug. We consider a penalized multiple-response regression estimator using both generalized ℓ₁ norm and nuclear norm regularizes based on the motivations that only a few genes are relevant to the effect of drug resistance responses and that some genes could have similar effects on multiple responses. For the statistical properties, we developed non-asymptotic error bounds of the proposed estimator. In our numerical analysis using simulated and CCLE data, the proposed method better predicts the drug responses than the other methods.

Present and Future of Food Packaging Technology and Industry Toward Net-Zero

Youngjin Cho 한국식품영양과학회 2022 한국식품영양과학회 학술대회발표집 Vol.2022 No.10

Flexible Sensor Technology for Intelligent Food Packaging

Youngjin Cho 한국산업식품공학회 2022 식품과 기계 Vol.19 No.1

Self-Aggregated N-Acyl Chitosan Nanoparticle for Enhancing Sustained Release Property

( Youngjin Cho ),( Jun Tae Kim ),( Hyun Jin Park ) 한국키틴키토산학회 2021 한국키틴키토산학회지 Vol.26 No.1

N-acyl chitosans (N-acyl CSs) with various hydrophobic side chain length were synthesized to improve the resistance in acidic condition. The carrier for gentamicin was developed by N-acyl chitosan nanoparticles (N-acyl CSNPs), which were fabricated through self-aggregation method. N-acyl CSNPs were positive charged from 10.2 to 28.9 mV and the values were decreased from 4.2 to 11.1 mV after gentamicin loading. Particle sizes of N-acyl CSNPs increased from 208 to 480 nm with side chain length. When gentamicin was loaded into N-acyl CSNPs, the particle size decreased by up to 50%. Encapsulation efficiency was around 46-62%. In vitro release profiles of gentamicin in N-acyl CSNPs showed the sustained release properties during one week at pH 1.3 and pH 7.4. Therefore, gentamicin were efficiently loaded into N-acyl CSNPs, these nanoparticles showed a good morphology, nano-size distribution, and controlled release at acidic as well as neutral conditions that permit to propose them as a superior candidate for the delivery of gentamicin.

Selenization of CIG Precursors Using RTP Method with Se Cracker Cell

Youngjin Kang,Hyejin Song,Yousuk Cho,Jongman Yoon,Yongdeuk Jung,Deahyung Cho,Juhee Kim,Sujung Park 한국진공학회 2012 한국진공학회 학술발표회초록집 Vol.2012 No.8

Bifunctional Sensing Characteristics of Chemical Vapor Deposition Synthesized Atomic-Layered MoS₂

Cho, Byungjin,Kim, Ah Ra,Park, Youngjin,Yoon, Jongwon,Lee, Young-Joo,Lee, Sangchul,Yoo, Tae Jin,Kang, Chang Goo,Lee, Byoung Hun,Ko, Heung Cho,Kim, Dong-Ho,Hahm, Myung Gwan American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.4

<P>Two-dimensional (2D) molybdenum disulfide (MoS<SUB>2</SUB>) atomic layers have a strong potential to be adopted for 2D electronic components due to extraordinary and novel properties not available in their bulk foams. Unique properties of the MoS<SUB>2</SUB>, including quasi-2D crystallinity, ultrahigh surface-to-volume, and a high absorption coefficient, have enabled high-performance sensor applications. However, implementation of only a single-functional sensor presents a limitation for various advanced multifunctional sensor applications within a single device. Here, we demonstrate the charge-transfer-based sensitive (detection of 120 ppb of NO<SUB>2</SUB>) and selective gas-sensing capability of the chemical vapor deposition synthesized MoS<SUB>2</SUB> and good photosensing characteristics, including moderate photoresponsivity (∼71 mA/W), reliable photoresponse, and rapid photoswitching (<500 ms). A bifunctional sensor within a single MoS<SUB>2</SUB> device to detect photons and gas molecules in sequence is finally demonstrated, paving a way toward a versatile sensing platform for a futuristic multifunctional sensor.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-4/am508535x/production/images/medium/am-2014-08535x_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am508535x'>ACS Electronic Supporting Info</A></P>