Porous Si nanowires for highly selective room-temperature NO₂ gas sensing

Kwon, Yong Jung,Mirzaei, Ali,Na, Han Gil,Kang, Sung Yong,Choi, Myung Sik,Bang, Jae Hoon,Oum, Wansik,Kim, Sang Sub,Kim, Hyoun Woo IOP 2018 Nanotechnology Vol.29 No.29

<P>We report the room-temperature sensing characteristics of Si nanowires (NWs) fabricated from p-Si wafers by a metal-assisted chemical etching method, which is a facile and low-cost method. X-ray diffraction was used to the the study crystallinity and phase formation of Si NWs, and product morphology was examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). After confirmation of Si NW formation via the SEM and TEM micrographs, sensing tests were carried out at room temperature, and it was found that the Si NW sensor prepared from Si wafers with a resistivity of 0.001–0.003 Ω.cm had the highest response to NO<SUB>2</SUB> gas (R<SUB>g</SUB>/R<SUB>a</SUB>?=?1.86 for 50 ppm NO<SUB>2</SUB>), with a fast response (15 s) and recovery (30 s) time. Furthermore, the sensor responses to SO<SUB>2</SUB>, toluene, benzene, H<SUB>2</SUB>, and ethanol were nearly negligible, demonstrating the excellent selectivity to NO<SUB>2</SUB> gas. The gas-sensing mechanism is discussed in detail. The present sensor can operate at room temperature, and is compatible with the microelectronic fabrication process, demonstrating its promise for next-generation Si-based electronics fused with functional chemical sensors.</P>

Dual sensitization of MWCNTs by co-decoration with p- and n-type metal oxide nanoparticles

Choi, Myung Sik,Bang, Jae Hoon,Mirzaei, Ali,Na, Han Gil,Kwon, Yong Jung,Kang, Sung Yong,Choi, Sun-Woo,Kim, Sang Sub,Kim, Hyoun Woo Elsevier 2018 Sensors and actuators. B Chemical Vol.264 No.-

<P><B>Abstract</B></P> <P>We present a dual sensitization gas sensor for selective detection of either H<SUB>2</SUB>S or C<SUB>2</SUB>H<SUB>5</SUB>OH gases, based on ZnO/CuO nanoparticle (NP)-decorated MWCNTs. First, Cu-Zn layers of three different thickness (3, 6, 9 nm) were successfully deposited on the surfaces of CNTs by a sputtering process and subsequently converted to their corresponding oxides by thermal annealing. The gas sensing characteristics of metal oxide decorated-MWCNTs were studied in the presence of three gases, namely NO<SUB>2</SUB>, H<SUB>2</SUB>S, and C<SUB>2</SUB>H<SUB>5</SUB>OH. The best sensing properties were obtained when the Cu-Zn deposition layer was 6 nm thick. The optimized sensor showed extraordinary responses to both H<SUB>2</SUB>S and C<SUB>2</SUB>H<SUB>5</SUB>OH gases at working temperatures of 100 °C and 200 °C, respectively. Therefore, selectivity was tuned by selection of the working temperature. The sensing mechanisms of the metal oxide-decorated CNTs sensors are discussed in detail. The approach described, namely co-decoration of the surfaces of MWCNTs with different metal oxides, will be of great utility to researchers who wish to fabricate dual sensitive gas sensors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We present a dual sensitization sensor for selective detection of either H<SUB>2</SUB>S or C<SUB>2</SUB>H<SUB>5</SUB>OH gases. </LI> <LI> Dual sensitization was devised, where two different metal oxides are added to the host material. </LI> <LI> The possible sensing mechanisms of the metal oxide-decorated CNTs sensors are discussed. </LI> </UL> </P>

Selective detection of low concentration toluene gas using Pt-decorated carbon nanotubes sensors

Kwon, Yong Jung,Na, Han Gil,Kang, Sung Yong,Choi, Sun-Woo,Kim, Sang Sub,Kim, Hyoun Woo Elsevier 2016 Sensors and actuators. B, Chemical Vol.227 No.-

<P><B>Abstract</B></P> <P>We demonstrated the preparation of high-performance toluene (C<SUB>7</SUB>H<SUB>8</SUB>) gas sensor, by using the Pt-multiwalled carbon nanotubes (MWCNTs) composite materials. We optimized the size of the Pt nanoparticles by controlling the predeposited Pt thickness, for obtaining the highest sensing performances. We have obtained the sensor responses of 3.91 and 5.06, at concentrations of 1 and 5ppm of C<SUB>7</SUB>H<SUB>8</SUB> gas, respectively, at 150°C. We discussed the associated sensing mechanisms and proposed the reasons why the Pt-functionalization drastically enhanced the sensing behaviors of the Pt-MWCNTs composite sensors selectively to C<SUB>7</SUB>H<SUB>8</SUB> gas.</P>

설련의 항산화능와 사람 섬유아세포에서 UVA에 의한 MMP-1발현 저해효과

심관섭 ( Gwan Sub Sim ),김진화 ( Jin Hwa Kim ),나영 ( Young Na ),이동환 ( Dong Hwan Lee ),이범천 ( Bum Chun Lee ),( Yong He Zhang ),표형배 ( Hyeong Bae Fy ) 대한화장품학회 2005 대한화장품학회지 Vol.31 No.4

노화와 연관하여 설련의 항산화 효과, in vitro MMP 활성 저해능, 자외선 조사에 의해 유도된 MMP-1 발현에 대한 영향을 사람섬유아세포를 이용하여 확인하였다. 설련의 항산화 효과를 알아보기 위하여 DPPH radical과 superoxide anion radical 소거효과를 측정하였다. 그 결과 DPPH radical 소거능의 IC₅₀ 값은 3.89 μg/mL이고, xanthine/xanthine oxidase에 의한 superoxide anion radical 제거능의 IC₅₀ 값은 67.29 μg/mL이었다. 설련 1000 μg/mL에서 93.27%의 지질과산화 저해효과를 나타내었다. MMP-1의 효소활성 저해 효과는 농도 의존적으로 활성을 억제하였으며, IC₅₀ 값은 97.18 μg/mL이다. 또한 자외선 조사에 의해 사람 섬유아세포에서 발현되는 MMP-1에 대해 단백질의 양적인 변화는 42.86% 감소되었으며, 설련에 의해 농도 의존적으로 MMP-1 mRNA의 발현량도 감소되었다. 이러한 실험결과를 통하여 설련은 항산화 효과뿐만 아니라 자외선 조사에 의해 유도되는 MMP-1 단백질 발현과 mRNA 유전자 수준에서의 조절이 가능함을 확인하였다. 결론적으로 설련은 항산화와 자외선으로부터 생성되는 MMP-1의 발현을 저해함으로써 노화와 따른 피부를 보호하는 항노화 소재로서의 응용가능성을 확인하였다. In order to investigate the effects of Saussurea involucrata on (relationship between) aging (and Saussurea involucrata), we examined the activities of antioxidation, in vitro MMP inhibition and UVA-induced MMP-1 expression in human dermal fibroblasts. S. involucrata showed scavenging activities radicals and reactive oxygen species (ROS) with the IC₅₀ values of 3.89 μg/mL against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 67.29 μg/mL against superoxide radicals in the xanthine/xanthine oxidase system, respectively. At the concentration of 1000 μg/mL, S. involucrata showed 93.27% inhibition on lipid peroxidation of linoleic acid. S. involucrata inhibited the activities of MMP-1 in a does-dependent manner and the IC₅₀ value calculated from semi-log plots was 97.18 μg/mL. Also, UVA induced MMP expression in human dermal fibroblasts was reduced 42.86% by treatment with S. involucrata, and MMP-1 mRNA expression was reduced in a dose-dependent manner. Therefore S. involucrata was able to significantly inhibit MMP expression in protein and mRNA level. All these results suggested that S. involucrata might act as an anti-aging agent by antioxidation and reducing UVA-induced MMP-1 production.

Enhanced Gas Sensing Characteristics of Ag₂O-Functionalized Networked In₂O₃Nanowires

Kim, Hyoun Woo,Na, Han Gil,Kwak, Dong Sub,Cho, Hong Yeon,Kwon, Yong Jung IOP Publishing 2013 Japanese journal of applied physics Vol.52 No.10

Usefulness of ROX Index and SpO₂/FiO₂ Ratio for Predicting High-flow Nasal Cannula Failure in Hypoxemic COVID-19 Patients

( Jin Hyoung Kim ),( Ae-rin Baek ),( Song-i Lee ),( Won-young Kim ),( Yong Sub Na ),( Bo Young Lee ),( Gil Myeong Seong ),( Moon Seong Baek ) 대한결핵 및 호흡기학회 2021 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.129 No.0

Background ROX index after high-flow nasal cannula (HFNC) initiation can be helpful to identify low-risk patients of HFNC failure in patients with acute hypoxemic respiratory failure. However, it remains unknown which variables are useful for predicting HFNC failure in coronavirus disease 2019 (COVID-19) receiving HFNC. This study aims to determine the discrimination ability of the ROX index and SpO2/FiO2 ratio in COVID-19 patients after HFNC initiation. Methods This multicenter study was conducted at seven university-affiliated hospitals in Korea. We retrospectively reviewed the hospitalized patients diagnosed with COVID-19 between February 10, 2020 and February 28, 2021. The ROX index and SpO2/ FiO2 ratio were calculated at 1 hour and 4 hours after HFNC initiation. The primary outcome was HFNC failure, defined as the subsequent use of mechanical ventilation despite using HFNC. Discrimination of prediction for HFNC failure was evaluated by receiver operating characteristic (ROC) curve analysis. Results During the study period, 1,565 patients with COVID-19 were hospitalized and eligible 133 patients who received HFNC were analyzed. Among them, 63 (47.4%) were successfully weaned from HFNC, and 70 (52.6%) were intubated. SpO2/FiO2 ratio at 1 hour after HFNC initiation was a more accurate predictor of HFNC failure compared to ROX index (AUC 0.762; 95% CI: 0.679- 0.846 vs. 0.733; 95% CI: 0.640-0.826) (Figure 1). In the multivariable analysis, patients older than 70 years old had 3.4 times of HFNC failure compared to younger patients (AUC 3.367 [95% CI: 1.358-8.349], p=0.009), and SpO2/FiO2 at 1 hour (AUC 0.983 [95% CI: 0.972-0.994], p=0.003) were associated with HFNC failure. Conclusions SpO2/FiO2 ratio at 1 hour after HFNC initiation demonstrated a useful predictive ability for HFNC failure. SpO2/FiO2 could be a bedside tool to identify the need for mechanical ventilation in COVID-19 patients receiving HFNC.

Two cases of interstitial lung disease induced by the root of achyranthes japonica nakai

( Yong Sub Na ) 대한결핵 및 호흡기학회 2019 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.127 No.-

Introduction:An ever-increasing number of drugs can reproduce variegated patterns of naturally occurring interstitial lung disease. Achyranthes japonicaNakai is a perennial herb. Its roots called “Useul-ppuli” have been traditionally used to control pain and improve dysfunction in osteoarthritis patients in Korea. We present two cases of interstitial lung disease induced by the root of Achyranthes japonicaNakai. Case Report: Case 1 A 83-year-old Korean female presented with a history of dyspnea for 2 days. She had been treated with medication for 5 years for osteoarthritis. From 2 weeks ago, she took the root of Achyranthes japonicaNakai by boiling. Chest radiograph showed diffuse bilateral coalescent opacities. Chest computed tomography (CT) showed bilateral ground glass opacities with interlobular interstitial thickening and patchy consolidation. Upon arrival to the emergency department, Arterial saturation was 74.9% in the room air. High-flow nasal oxygen cannula was initiated with fraction of inspired oxygen of 0.6 and 50 L/min flow. Treatment with glucocorticoids and empirical antibiotics was started. After 7 days, she showed improvement in symptoms. Chest CT showed almost improvement of ground glass opacities and patchy consolidation. Case 2 A 71-year-old Korean female was admitted to our hospital with dyspnea, febrile sensation. She had been diagnosed with rheumatoid arthritis 5 years ago. She took the root of Achyranthes japonicaNakai by boiling to control joint pain from a month ago. Chest CT showed bilateral areas of ground glass opacities and patchy consolidation (Figure 1). After admission, she was intubated due to acute respiratory distress. She was treated with glucocorticoids pulse therapy and empirical antibiotics. Three days after treatment, hypoxemia had resolved, and extubation was performed. After 12 days of treatment with glucocorticoids chest radiograph showed improve ment of diffuse bilateral opacities. Conclusion: This case report suggest that clinicians should be cautious regarding herb or herbal medicine induced interstitial lung disease.

Clinical Phenotype of a First Unprovoked Acute Pulmonary Embolism Associated with Antiphospholipid Antibody Syndrome

Na, Yong Sub,Jang, Seongsoo,Hong, Seokchan,Oh, Yeon Mok,Lee, Sang Do,Lee, Jae Seung The Korean Academy of Tuberculosis and Respiratory 2019 Tuberculosis and Respiratory Diseases Vol.82 No.1

Background: Antiphospholipid antibody syndrome (APS), an important cause of acquired thrombophilia, is diagnosed when vascular thrombosis or pregnancy morbidity occurs with persistently positive antiphospholipid antibodies (aPL). APS is a risk factor for unprovoked recurrence of pulmonary embolism (PE). Performing laboratory testing for aPL after a first unprovoked acute PE is controversial. We investigated if a specific phenotype existed in patients with unprovoked with acute PE, suggesting the need to evaluate them for APS. Methods: We retrospectively reviewed patients with PE and APS (n=24) and those with unprovoked PE with aPL negative (n=44), evaluated 2006-2016 at the Asan Medical Center. We compared patient demographics, clinical manifestations, laboratory findings, and radiological findings between the groups. Results: On multivariate logistic regression analysis, two models of independent risk factors for APS-PE were suggested. Model I included hemoptysis (odds ratio [OR], 12.897; 95% confidence interval [CI], 1.025-162.343), low PE severity index (OR, 0.948; 95% CI, 0.917-0.979), and activated partial thromboplastin time (aPTT; OR, 1.166; 95% CI, 1.040-1.307). Model II included age (OR, 0.930; 95% CI, 0.893-0.969) and aPTT (OR, 1.104; 95% CI, 1.000-1.217). Conclusion: We conclude that patients with first unprovoked PE with hemoptysis and are age <40; have a low pulmonary embolism severity index, especially in risk class I-II; and/or prolonged aPTT (above 75th percentile of the reference interval), should be suspected of having APS, and undergo laboratory testing for aPL.

Clinical Outcomes and Risk Factors of Secondary Infection in Patients with Severe COVID-19: A Multicentre Cohort Study in Korea

( Yong Sub Na ),( Ae-rin Baek ),( Moon Seong Baek ),( Won-young Kim ),( Jin Hyoung Kim ),( Bo Young Lee ),( Gil Myeong Seong ),( Song-i Lee ) 대한결핵 및 호흡기학회 2021 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.129 No.-

Background and objective Secondary infection with the influenza virus occurs in critically ill patients and is associated with substantial morbidity and mortality; however, information remains limited about it in patients with severe COVID-19. Thus, we investigated the clinical outcomes and risk factors of secondary infections in patients with severe COVID-19. Methods This multicentre retrospective cohort study included patients with severe COVID-19 who were admitted to seven tertiary or referral hospitals in South Korea from February 2, 2020, to February 28, 2021. Multivariate logistic regression analyses were performed to assess factors associated with the risk of secondary infections. Results Of the 348 included patients, 120 (34.5%) had at least one infection and 228 (65.5%) had no infection. The most common pathogens of hospital-acquired or ventilator-associated pneumonia were Acinetobacter baumannii (24/92, 26.1%), and of bloodstream infections or central line-associated bloodstream infections were coagulase-negative staphylococci (9/36, 25.0%), and of catheter-associated urinary tract infections were Escherichia coli (9/17, 52.9%) (Figure 1). The time of diagnosis of infection was 16.0 ± 13.7 days from symptom onset and 10.6 ± 12.9 days from hospital admission. There was no statistically significant difference in the 28-day mortality (Table 1). However, in-hospital mortality was higher in the infected group. The risk factors for secondary infection were APACHE II, frailty scale, and corticosteroid use (Table 2). Conclusions In patients with severe COVID-19 and secondary infections, in-hospital mortality was more than doubled. A higher APACHE II score, frailty scale, and use of steroids were risk factors for secondary infection.

Clinical practices to detect and to manage patients with antiphospholipid syndrome and VTE

( Yong Sub Na ) 대한결핵 및 호흡기학회 2019 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.127 No.-