Liquid-liquid phase separation in particles containing secondary organic material free of inorganic salts

Song, Mijung,Liu, Pengfei,Martin, Scot T.,Bertram, Allan K. Copernicus GmbH 2017 Atmospheric Chemistry and Physics Vol.17 No.18

<P>Abstract. Particles containing secondary organic material (SOM) are ubiquitous in the atmosphere and play a role in climate and air quality. Recently, research has shown that liquid-liquid phase separation (LLPS) occurs at high relative humidity (RH) (greater than ∼ 95 %) in α-pinene-derived SOM particles free of inorganic salts, while LLPS does not occur in isoprene-derived SOM particles free of inorganic salts. We expand on these findings by investigating LLPS at 290 ± 1 K in SOM particles free of inorganic salts produced from ozonolysis of β-caryophyllene, ozonolysis of limonene, and photo-oxidation of toluene. LLPS was observed at greater than ∼ 95 % RH in the biogenic SOM particles derived from β-caryophyllene and limonene while LLPS was not observed in the anthropogenic SOM particles derived from toluene. This work combined with the earlier work on LLPS in SOM particles free of inorganic salts suggests that the occurrence of LLPS in SOM particles free of inorganic salts is related to the oxygen-to-carbon elemental ratio (O : C) of the organic material. These results help explain the difference between the hygroscopic parameter κ of SOM particles measured above and below water saturation in the laboratory and field, and have implications for predicting the cloud condensation nucleation properties of SOM particles. </P>

Liquid-liquid phase separation in organic particles containing one and two organic species: importance of the average O : C

Song, Mijung,Ham, Suhan,Andrews, Ryan J.,You, Yuan,Bertram, Allan K. Copernicus GmbH 2018 Atmospheric Chemistry and Physics Vol.18 No.16

<P>Abstract. Recently, experimental studies have shown that liquid-liquid phase separation (LLPS) can occur in organic particles free of inorganic salts. Most of these studies used organic particles consisting of secondary organic materials generated in environmental chambers. To gain additional insight into LLPS in organic particles free of inorganic salts, we studied LLPS in organic particles consisting of one and two commercially available organic species. For particles containing one organic species, three out of the six particle types investigated underwent LLPS. In these cases, LLPS was observed when the O : C was ≤ 0.44 (but not always) and the relative humidity (RH) was between ∼ 97 % and ∼ 100 %. The mechanism of phase separation was likely nucleation and growth. For particles containing two organic species, 13 out of the 15 particle types investigated underwent LLPS. In these cases, LLPS was observed when the O : C was ≤ 0.58 (but not always) and mostly when the RH was between ∼ 90 % RH and ∼ 100 % RH. The mechanism of phase separation was likely spinodal decomposition. In almost all cases when LLPS was observed (for both one-component and two-component particles), the highest RH at which two liquids was observed was 100±2.0 %, which has important implications for the cloud condensation nuclei (CCN) properties of these particles. These combined results provide additional evidence that LLPS needs to be considered when predicting the CCN properties of organic particles in the atmosphere. </P>

Relative humidity-dependent viscosity of secondary organic material from toluene photo-oxidation and possible implications for organic particulate matter over megacities

Song, Mijung,Liu, Pengfei F.,Hanna, Sarah J.,Zaveri, Rahul A.,Potter, Katie,You, Yuan,Martin, Scot T.,Bertram, Allan K. Copernicus GmbH 2016 Atmospheric Chemistry and Physics Vol.16 No.14

<P>Abstract. To improve predictions of air quality, visibility, and climate change, knowledge of the viscosities and diffusion rates within organic particulate matter consisting of secondary organic material (SOM) is required. Most qualitative and quantitative measurements of viscosity and diffusion rates within organic particulate matter have focused on SOM particles generated from biogenic volatile organic compounds (VOCs) such as α-pinene and isoprene. In this study, we quantify the relative humidity (RH)-dependent viscosities at 295 ± 1 K of SOM produced by photo-oxidation of toluene, an anthropogenic VOC. The viscosities of toluene-derived SOM were 2 × 10−1 to ∼ 6 × 106 Pa s from 30 to 90 % RH, and greater than ∼ 2 × 108 Pa s (similar to or greater than the viscosity of tar pitch) for RH ≤ 17 %. These viscosities correspond to Stokes-Einstein-equivalent diffusion coefficients for large organic molecules of ∼ 2 × 10−15 cm2 s−1 for 30 % RH, and lower than ∼ 3 × 10−17 cm2 s−1 for RH ≤ 17 %. Based on these estimated diffusion coefficients, the mixing time of large organic molecules within 200 nm toluene-derived SOM particles is 0.1-5 h for 30 % RH, and higher than ∼ 100 h for RH ≤ 17 %. As a starting point for understanding the mixing times of large organic molecules in organic particulate matter over cities, we applied the mixing times determined for toluene-derived SOM particles to the world's top 15 most populous megacities. If the organic particulate matter in these megacities is similar to the toluene-derived SOM in this study, in Istanbul, Tokyo, Shanghai, and São Paulo, mixing times in organic particulate matter during certain periods of the year may be very short, and the particles may be well-mixed. On the other hand, the mixing times of large organic molecules in organic particulate matter in Beijing, Mexico City, Cairo, and Karachi may be long and the particles may not be well-mixed in the afternoon (15:00-17:00 LT) during certain times of the year. </P>

Viscosity of Secondary Organic Aerosol Particles and Implications for Particle Growth and Reactivity

Mijung Song,James W Grayson,Pengfei Liu,Yue Zhang,John E. Shilling,Mathieu Sellier,Benjamin J. Murray,Scot T Martin,Allan Bertram 한국대기환경학회 2014 한국대기환경학회 학술대회논문집 Vol.2014 No.10

Characteristics of PM<SUB>10</SUB> and PM<SUB>2.5</SUB> in Saemangeum Reclaimed Land, South Korea

Mijung Song,Sangmin Oh,Komal Narayan Pawar,Rani Jeong 한국대기환경학회 2021 한국대기환경학회 학술대회논문집 Vol.2021 No.10

The Clean Air Policy Support System (CAPSS) for the year of 2017 showed that fugitive dust is a main contributor of the total PM10 and PM2.5 emissions in Jeollabuk-do. Recently, there have been reports that fugitive dust from the Saemangeum reclaimed land is affecting even the downtown area. In order to characterize the chemical compositions of PM10 and PM2.5 in Saemangeum reclaimed land, we collected PM10 and PM2.5 filter samples from May 2020 to June 2021, and then analyzed the chemical compositions of water-soluble ions and elements in the PM10 and PM2.5. The results in Saemangeum reclaimed land will be presented.

생물기원 이차유기에어로졸의 점성도와 상 규명에 관한 최근 연구 동향

송미정(Mijung Song) 한국대기환경학회 2016 한국대기환경학회지 Vol.32 No.4

오징어 유래 포스파티딜세린(phosphatidylserine)의 in vitro 항염 효과

염미정(Mijung Yeom),박현정(Hyun-Jung Park),심현수(Hyun-Soo Shim),심인섭(Insop Shim),한정준(Jeong-Jun Han),정국훈(Guk Hoon Chung),허송욱(Song Her),정동명(Dong-Myong Jeong),함대현(Dae-Hyun Hahm) 대한스트레스학회 2011 스트레스硏究 Vol.19 No.1

본 연구에서는 Raw264.7 대식 세포주에서 lipopolysaccharide (LPS)로 유도된 tumor necrosis factor-alpha (TNF-α)와 interleukin-1 beta (IL-1β)의 분비에 대한 오징어 유래 포스파티딜세린(phosphatidylserine)의 효과를 확인하였다. Raw264.7 대식 세포주에서 PS의 세포독성 효과는 MTT 분석으로 조사하였으며, TNF-α와 IL-1β의 mRNA 및 단백질의 발현 정도는 각각 RT-PCR 및 ELISA 분석법으로 확인하였다. PS는 100μg/ml 농도까지는 세포 독성을 나타내지 않았으며, 세포 독성을 보이지 않는 농도에서 LPS로 유도된 IL-1β와 특히 TNF-α의 mRNA 및 단백질의 발현을 저해하였다. 이러한 실험 결과는 염증성 질환을 위한 유용한 물질로써 PS의 개발 가능성을 시사한다고 사료된다. In the present study, the effects of squid-derived phosphatidylserine (PS) have been evaluated on lipopolysaccharide (LPS)- induced release of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) in the macrophage Raw 264.7 cells. The cytotoxicity of PS in Raw 264.7 macrophages was measured by MTT-based cytotoxicity assay. The mRNA and protein levels of tumor necrosis factor (TNF)-α and interleukin (IL)-1β were measured by quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) and by enzyme-linked immunosorbent assay (ELISA), respectively. Cytotoxic effects of PS in Raw 264.7 macrophages were not observed at concentration up to 100 μg/ml. Squid PS inhibited the mRNA and protein expression of TNF-α but not IL-1β. Taken together, these results indicated that squid-originated PS exhibited a significant activity of anti-inflammation in vitro and might be a useful candidate for treating various inflammatory diseases. (Korean J Str Res 2011;19:89∼95)

Stromal vascular fraction injection to treat intractable radiation-induced rectovaginal fistula

Kim, Mijung,Lew, Dae Hyun,Roh, Tai Suk,Song, Seung Yong Korean Society of Plastic and Reconstructive Surge 2021 Archives of Plastic Surgery Vol.48 No.1

Rectovaginal fistula, which can arise after an injury to the vaginal canal or rectum, is a troublesome obstacle for patients' everyday life. In most cases, it can be covered with a local flap, but previous radiation therapy increases the recurrence rate, making it especially difficult to cure. As the application of stromal vascular fraction (SVF) obtained from enzymatically digested autologous adipose tissue has become increasingly common, several reports have advocated its effectiveness for the treatment of refractory wounds. In light of the angiogenic, regenerative characteristics of SVF, it was incorporated as a treatment option in two cases of rectovaginal fistula discussed here. As described in this report, irradiated rectovaginal fistulas in rectal cancer patients were successfully treated with SVF injection, and we suggest SVF as a feasible treatment option for cases of rectovaginal fistula that would otherwise be very difficult to cure.

Transcriptional induction of cyclooxygenase-2 in osteoclast precursors is involved in RANKL-induced osteoclastogenesis

Han, Song Yi,Lee, Na Kyung,Kim, Kyung Hee,Jang, In Whan,Yim, Mijung,Kim, Jae Hong,Lee, Won Jae,Lee, Soo Young American Society of Hematology 2005 Blood Vol.106 No.4

<B>Abstract</B><P>Regulation of osteoclast differentiation is key to understanding the pathogenesis and to developing treatments for bone diseases such as osteoporosis. To gain insight into the mechanism of the receptor activator of nuclear factor (NF)-κB ligand (RANKL)-specific induction of the osteoclast differentiation program, we took a suppression-subtractive hybridization screening approach to identify genes specifically induced via the RANKL-Rac1 signaling pathway. Among identified targets, we show that RANKL selectively induces cyclooxygenase (COX) 2 expression via Rac1 that results in turn in production of prostaglandin E2 (PGE2) in RAW 264.7 cells. By using transient transfection assays, we found that the -233/-206 region of the COX-2 promoter gene was critical for RANKL-induced promoter activity. This RANKL-responsive region contained an NF-κB site that, when mutated, completely abolished the induction of NF-κB DNA-binding activity by RANKL. Blockade of COX-2 by celecoxib inhibits differentiation of bone marrow-derived monocyte/macrophage precursor cells (BMMs) into tartrate-resistant acid phosphatase-positive (TRAP+) osteoclastic cells. This inhibition can be rescued by the addition of exogenous PGE2, suggesting that COX-2-dependent PGE2 induction by RANKL in osteoclast precursors is required for osteoclast differentiation.</P>

Differential expression in histologically normal crypts of ulcerative colitis suggests primary crypt disorder.

Kim, Mijung,Lee, Seungkoo,Yang, Suk-Kyun,Song, Kyuyoung,Lee, Inchul National Hellenic Research Foundation 2006 Oncology reports Vol.16 No.4

<P>Ulcerative colitis is characterized by crypt infiltration particularly of neutrophils. However, it is not known whether it reflects a primary crypt disorder or a secondary inflammatory response. In this study, we analyzed the expression profiles of histologically normal crypts microdissected from formalin-fixed biopsies of early stage ulcerative colitis. Total RNAs were extracted, amplified, and applied to Affymetrix GeneChip(R) X3P Array. For the control, similar crypts from nonspecific colitis biopsies were applied. A total of 353 (4.3%) and 111 (1.4%) genes were >3 times up-, and down-regulated in ulcerative colitis. Up-regulated genes included FCGBP (Fc fragment of IgG binding protein), cyclophilin A, chemokine (C-X-C motif) ligand 3, and genes associated with lipid metabolism. Down-regulated genes included APOA4 (apolipoprotein A-IV), cylindromatosis, BCL2-like 10, claudin 8, and numerous transcriptional regulators. FCGBP and APOA4 have been implicated in ulcerative colitis previously. Our data show differential expression in the crypt epithelia of ulcerative colitis before active inflammation is initiated, suggesting primary crypt abnormalities that might be implicated in the pathogenesis of ulcerative colitis.</P>