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- 저자 : Heejin Hwang (검색결과 95 건)
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Hwang, HeeJin,Ro, Chul-Un Elsevier 2006 Atmospheric environment Vol.40 No.16
<P><B>Abstract</B></P><P>Environmentally benign treatment of municipal solid waste (MSW) ashes has been a worldwide issue since more countries are implementing incineration to reduce waste volume. A single-particle analytical technique, named low-<I>Z</I> particle electron probe X-ray microanalysis (low-<I>Z</I> particle EPMA) was applied to characterize MSW fly- and bottom-ash particle samples collected from two municipal incinerators in Korea. According to their chemical composition, many distinctive particle types were identified. For fly ash sample collected in one incinerator (sample S1), where lime slurry injection is used for acid–gas treatment, CaCO<SUB>3</SUB>-containing particles (28.4%) are the most abundantly encountered, followed by carbonaceous (23.6%), SiO<SUB>2</SUB>-containing (13.8%), NaCl-containing (13.1%), and iron-containing (10.5%) particles. For fly ash sample collected at the other incinerator (sample S2), NaCl-containing particles (40.4%) are the most abundantly encountered, followed by iron-containing (29.1%), carbonaceous (11.8%), CaCO<SUB>3</SUB>-containing (2.2%), and SiO<SUB>2</SUB>-containing (7.0%) particles.</P><P>For bottom ash sample collected at one incinerator (sample S3), iron-containing particles (46.6%) are the most abundantly encountered, followed by CaCO<SUB>3</SUB>-containing (17.3%), carbonaceous (16.6%), and Si and/or Al oxide-containing (15.8%) particles. For bottom ash sample collected in the other incinerator (sample S4), iron-containing particles (63.4%) are also the most abundantly encountered, followed by carbonaceous (14.0%), CaCO<SUB>3</SUB>-containing (10.0%), and Si and/or Al oxide-containing (6.1%) particles. Chemical compositions of the two bottom ash samples are not much different compared to those of the two fly ash samples.</P><P>It was demonstrated that the single-particle characterization using this low-<I>Z</I> particle EPMA technique provided detailed information on various types of chemical species in the MSW ash samples. In addition, the technique has advantage over conventional analytical techniques in the point that both crystalline- and glass-like ash particles can be analyzed at the same time.</P>
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Hwang, HeeJin,Ro, Chul-Un Elsevier 2006 Atmospheric environment Vol.40 No.21
<P><B>Abstract</B></P><P>In the present work, it is demonstrated that a single particle analytical technique, named low-<I>Z</I> particle electron probe X-ray microanalysis, is a practically useful tool for the study of heterogeneous reactions of mineral dust and sea-salts when this analytical technique was applied to a sample collected during an Asian Dust storm event. The technique does not require a special treatment of sample to identify particles reacted in the air. Also, quantitative chemical speciation of reacted particles can provide concrete information on what chemical reaction, if any, occurred for individual particles. Among overall 178 analyzed particles, the number of reacted particles is 81 and heterogeneous chemical reactions mostly occurred on CaCO<SUB>3</SUB> mineral dust (54 particles) and sea-salts (26 particles). Several observations made for the Asian Dust sample in the present work are: (1) CaCO<SUB>3</SUB> species almost completely reacted to produce mostly Ca(NO<SUB>3</SUB>)<SUB>2</SUB> species, and CaSO<SUB>4</SUB> to a much lesser extent. (2) When reacted particles contain CaSO<SUB>4</SUB>, almost all of them are internally mixed with nitrate. (3) Reacted CaCO<SUB>3</SUB> particles seem to contain moisture when they were collected. (4) Some reacted CaCO<SUB>3</SUB> particles have unreacted mineral species, such as aluminosilicates, iron oxide, SiO<SUB>2</SUB>, etc., in the core region. (5) All sea-salt particles are observed to have reacted in the air. Some of them were recrystallized in the air before being collected and they are observed as crystalline NaNO<SUB>3</SUB> particles. (6) Many sea-salts were collected as water drops, and some of them were fractionally recrystallized on Ag collecting substrate. When sea-salts were not recrystallized on the substrate, they are found as particles internally mixed with NaNO<SUB>3</SUB> and Mg(NO<SUB>3</SUB>)<SUB>2</SUB>, and in some cases SO<SUB>4</SUB> and Cl species as additional anions.</P>
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Hwang, Heejin,Hur, Soon Do,Lee, Jeonghoon,Han, Yeongcheol,Hong, Sungmin,Motoyama, Hideaki Elsevier 2019 Science of the Total Environment Vol.669 No.-
<P><B>Abstract</B></P> <P>Anthropogenic plutonium (Pu) in the environment is a result of atmospheric nuclear testing during the second half of the 20th century. In this work, we analyzed a 4-meter deep Antarctic Plateau snowpack characterized by a low snow accumulation rate and negligible snow impurities. These sample conditions enabled us to measure the snowpack Pu fallout by applying inductively coupled plasma sector field mass spectrometry to a few mL of snow melt without purification or preconcentration. Pu concentrations in the reconstructed Pu fallout record for the period after 1956 CE increased and decreased in agreement with past atmospheric nuclear testing. Two peaks and two dips associable with historical events were observed, and the highest peak in 1964(±1) CE approximately coincided with the maximum concentration of non-sea-salt sulfate caused by the Mt. Agung eruption in 1963 CE. Enhanced Pu fallout in the 1970s was attributed the geographical proximity of the Southern Hemispheric nuclear test sites. Our results suggest that by improving the instrumental sensitivity and precision, the potential of the Antarctic ice sheet as an archive of Pu fallout can be further explored and utilized for understanding atmospheric dispersion and for dating ice cores.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Atmospheric nuclear explosions in 1940–1980 caused global dispersion of plutonium. </LI> <LI> ICP-SFMS detected fallout <SUP>239</SUP>Pu from only a few grams of Antarctic Plateau snow. </LI> <LI> Purification and preconcentration of Pu were not necessary. </LI> <LI> Reconstructed <SUP>239</SUP>Pu fallout agreed with atmospheric nuclear explosion history. </LI> <LI> Potential of Pu as an atmospheric tracer and an age marker can be further utilized. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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Heejin Lim,Eunju Yeo,Eunju Song,Yun-Hee Chang,Bok-Kyung Han,Hyuk-Joon Choi,Jinah Hwang 한국영양학회 2015 Nutrition Research and Practice Vol.9 No.6
BACKGROUND/OBJECTIVES: Citrus flavonoids have a variety of physiological properties such as anti-oxidant, anti-inflammation, anti-cancer, and anti-obesity. We investigated whether bioconversion of Citrus unshiu with cytolase (CU-C) ameliorates the anti-adipogenic effects by modulation of adipocyte differentiation and lipid metabolism in 3T3-L1 cells. MATERIALS/METHODS: Glycoside forms of Citrus unshiu (CU) were converted into aglycoside forms with cytolase treatment. Cell viability of CU and CU-C was measured at various concentrations in 3T3L-1 cells. The anti-adipogenic and lipolytic effects were examined using Oil red O staining and free glycerol assay, respectively. We performed real time-polymerase chain reaction and western immunoblotting assay to detect mRNA and protein expression of adipogenic transcription factors, respectively. RESULTS: Treatment with cytolase decreased flavanone rutinoside forms (narirutin and hesperidin) and instead, increased flavanone aglycoside forms (naringenin and hesperetin). During adipocyte differentiation, 3T3-L1 cells were treated with CU or CU-C at a dose of 0.5 mg/ml. Adipocyte differentiation was inhibited in CU-C group, but not in CU group. CU-C markedly suppressed the insulin-induced protein expression of CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor gamma (PPARγ) as well as the mRNA levels of CEBPα, PPARγ, and sterol regulatory element binding protein 1c (SREBP1c). Both CU and CU-C groups significantly increased the adipolytic activity with the higher release of free glycerol than those of control group in differentiated 3T3-L1 adipocytes. CU-C is particularly superior in suppression of adipogenesis, whereas CU-C has similar effect to CU on stimulation of lipolysis. CONCLUSIONS: These results suggest that bioconversion of Citrus unshiu peel extracts with cytolase enhances aglycoside flavonoids and improves the anti-adipogenic metabolism via both inhibition of key adipogenic transcription factors and induction of adipolytic activity.
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Hwang Ji-Hee,Lim Minyoung,Han Gyeongjin,Park Heejin,Kim Yong-Bum,Park Jinseok,Jun Sang-Yeop,Lee Jaeku,Cho Jae-Woo 한국독성학회 2023 Toxicological Research Vol.39 No.3
Deep learning has recently become one of the most popular methods of image analysis. In non-clinical studies, several tissue slides are generated to investigate the toxicity of a test compound. These are converted into digital image data using a slide scanner, which is then studied by researchers to investigate abnormalities, and the deep learning method has been started to adopt in this study. However, comparative studies evaluating different deep learning algorithms for analyzing abnormal lesions are scarce. In this study, we applied three algorithms, SSD, Mask R-CNN, and DeepLabV3+, to detect hepatic necrosis in slide images and determine the best deep learning algorithm for analyzing abnormal lesions. We trained each algorithm on 5750 images and 5835 annotations of hepatic necrosis including validation and test, augmented with 500 image tiles of 448 × 448 pixels. Precision, recall, and accuracy were calculated for each algorithm based on the prediction results of 60 test images of 2688 × 2688 pixels. The two segmentation algorithms, DeepLabV3+ and Mask R-CNN, showed over 90% of accuracy (0.94 and 0.92, respectively), whereas SSD, an object detection algorithm, showed lower accuracy. The trained DeepLabV3+ outperformed all others in recall while also successfully separating hepatic necrosis from other features in the test images. It is important to localize and separate the abnormal lesion of interest from other features to investigate it on a slide level. Therefore, we suggest that segmentation algorithms are more appropriate than object detection algorithms for use in the pathological analysis of images in non-clinical studies.
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