Control of silica-zirconia nanoparticles for uniform porous SiO2-ZrO2 membranes.

Ryeon Lee, Hye,Lee, Jinkyeong,Seo, Bongkuk American Scientific Publishers 2014 Journal of Nanoscience and Nanotechnology Vol.14 No.11

<P>Silica-zirconia composite sols were prepared by means of a sol-gel method, using tetraethylorthosilicate (TEOS) and zirconium tetra-n-butoxide (ZrTB) precursors. TEOS, ZrTB, HCl, H2O and EtOH were mixed at 70 degrees C for 24 hours to give molar ratios of 1:1:8-80:0.2-1.0:100-300. The mean particle size of the silica-zirconia sol was controlled by the concentration of the alkoxides and catalyst, as well as the water molar ratio in the starting solution. The particle size of the SiO2-ZrO2 sol, which was analyzed by dynamic light scattering (DLS) and field emission scanning electron microscopy (FE-SEM), was in the range of 20 to 350 nm. The SiO2-ZrO2 sol solutions of different sol sizes were coated onto porous stainless steel supports (O.D. 10 mm, length: 20 mm, 316L SUS, Mott corp. USA) by a dipping-rolling-freezing-fast drying (DRFF) and soaking-rolling-freezing-fast drying (SRFF) method. After coating with SiO2-ZrO2 sol, the single gas permeation characteristics (He, H2 and N2) of the resulting SiO2-ZrO2 membranes were evaluated at room temperature. This produced a decrease in the mean flow diameter and H2/N2 permselectivity in the range of 2.0-3.5. Finally, following the results of gas permeation testing, the pore size of the membranes was controlled by changing their particle size.</P>

Separation of Dichlorinated Bydrocarbons by Pervaporntion Using ZSM-5 Zeolite Membrane

Lee, Young-Jin,Lee, Hye-Ryeon,Shim, Eun-Young,Ahn, Hyo-Sung,Lee, Yong-Taek The Membrane Society of Korea 2005 Korean Membrane Journal Vol.7 No.1

Pervaporation with a membrane is one of the economic technologies for separation of liquid mixtures including organic/water mixtures. The ZSM-5 membrane was used fur pervaporation of dichloromethane, 1,2-dichloroethane and trans-1,2-dichloroethylene from their aqueous solutions since its physical property shows very hydrophobic. ZSM-5 crystals were hydrothermally grown and deposited on the inside of a porous sintered stainless steel tube by the secondary growth method. Fluxes of dichlorinated organic compounds were observed to be $50{\~}429\;g/m^2/h$ while separation factors were $15{\~}320$ depending on a mole fraction of a dichlorinated organic compound in a feed solution ranged from 0.0001 to 0.001 mole fraction and the operation temperature between $25^{\circ}C\;and\;35^{\circ}C$.

Clinical Features and Risk Factors for Development of Breakthrough Gram-Negative Bacteremia during Carbapenem Therapy

Lee, Ji-Yong,Kang, Cheol-In,Ko, Jae-Hoon,Lee, Woo Joo,Seok, Hye-Ri,Park, Ga Eun,Cho, Sun Young,Ha, Young Eun,Chung, Doo Ryeon,Lee, Nam Yong,Peck, Kyong Ran,Song, Jae-Hoon American Society for Microbiology 2016 Antimicrobial Agents and Chemotherapy Vol.60 No.11

<B>ABSTRACT</B><P>With the increasing use of carbapenems, carbapenem-resistant Gram-negative bacteria have become a major concern in health care-associated infections. The present study was performed to evaluate the clinical and microbiological features of breakthrough Gram-negative bacteremia (GNB) during carbapenem therapy and to assess risk factors for development of breakthrough GNB. A case-control study was performed at a tertiary hospital from 2005 to 2014. Case patients were defined as individuals whose blood cultures grew Gram-negative bacteria while the patients were receiving carbapenems for at least 48 h before breakthrough GNB. Age-, sex-, and date-matched controls were selected from patients who received carbapenem for at least 48 h and did not develop breakthrough GNB during carbapenem treatment. A total of 101 cases of breakthrough GNB were identified and compared to 100 controls. The causative microorganisms for breakthrough GNB wereStenotrophomonas maltophilia(<I>n</I>= 33),Acinetobacter baumannii(<I>n</I>= 32),Pseudomonas aeruginosa(<I>n</I>= 21), and others (<I>n</I>= 15). Approximately 90% ofS. maltophiliaisolates were susceptible to levofloxacin and trimethoprim-sulfamethoxazole. The most common infection types were primary bacteremia (38.6%) and respiratory infections (35.6%). More than half of the patients died within a week after bacteremia, and the 30-day mortality rate was 70.3%. In a multivariate analysis, a longer hospital stay, hematologic malignancy, persistent neutropenia, immunosuppressant use, and previous colonization by causative microorganisms were significantly associated with breakthrough GNB. Our data suggest thatS. maltophilia,A. baumannii, andP. aeruginosaare the major pathogens of breakthrough GNB during carbapenem therapy, in association with a longer hospital stay, hematologic malignancy, persistent neutropenia, immunosuppressant use, and previous colonization.</P>

Long-term outcomes of abdominal paraganglioma

Hye Ryeon Choi,Zeng Yap,Soon Min Choi,Sun Hyung Choi,Jin Kyong Kim,Cho Rok Lee,Jandee Lee,Jong Ju Jeong,Kee-Hyun Nam,Woong Youn Chung,Sang-Wook Kang 대한외과학회 2020 Annals of Surgical Treatment and Research(ASRT) Vol.99 No.6

Purpose: Paragangliomas (PGL) are rare neuroendocrine tumors derived from chromaffin cells of the autonomic nervous system. We aim to describe our experience and the long-term outcome of abdominal PGL over the last decade. Methods: A retrospective review of patients diagnosed with PGL in our hospital between November 2005 and June 2017 was conducted. All nonabdominal PGL were excluded and the clinicopathological features and long-term outcomes of the patients were analyzed. Results: A total of 46 patients were diagnosed with abdominal PGL. The average age of diagnosis was 55.4 years and there was no sex predilection. The average tumor size was 5.85 cm and they were predominantly located in the infrarenal position (50%). The mean follow-up period was 42 months (range, 1.8–252 months). All patients with metastases had Pheochromocytoma of the Adrenal Gland Scaled Score (PASS) of ≥4. One patient presented with synchronous metastases while 2 developed local recurrence and distant metastases. One presented with only local recurrence. One patient died 5 years after diagnosis. Conclusion: Abdominal PGL is a rare tumor with excellent long-term prognosis. Recurrence although uncommon, can occur decades after initial diagnosis. Long-term follow-up is therefore recommended for all patients with PGL, especially in patients with PASS of ≥4

The Effect of Idesolide on Hippocampus-dependent Recognition Memory

Lee, Hye-Ryeon,Choi, Jun-Hyeok,Lee, Nuribalhae,Kim, Seung-Hyun,Kim, Young-Choong,Kaang, Bong-Kiun The Korean Society for Integrative Biology 2008 Animal cells and systems Vol.12 No.1

Finding a way to strengthen human cognitive functions, such as learning and memory, has been of great concern since the moment people realized that these functions can be affected and even altered by certain chemicals. Since then, plenty of endeavors have been made to look for safe ways of improving cognitive performances without adverse side-effects. Unfortunately, most of these efforts have turned out to be unsuccessful until now. In this study, we examine the effect of a natural compound, idesolide, on hippocampus-dependent recognition memory. We demonstrate that idesolide is effective in the enhancement of recognition memory, as measured by a novel object recognition task. Thus, idesolide might serve as a novel therapeutic medication for the treatment of memoryrelated brain anomalies such as mild cognitive impairment(MCI) and Alzheimer's disease.

Pituitary Adenylate Cyclase-activating Polypeptide (PACAP) Targets Down Syndrome Candidate Region 1 (DSCR1/RCAN1) to control Neuronal Differentiation

Lee, Eun Hye,Kim, Seon Sook,Lee, Seul,Baek, Kwan-Hyuck,Seo, Su Ryeon American Society for Biochemistry and Molecular Bi 2015 The Journal of biological chemistry Vol.290 No.34

<P>Pituitary adenylate cyclase-activating peptide (PACAP) is a neurotrophic peptide involved in a wide range of nervous functions, including development, differentiation, and survival, and various aspects of learning and memory. Here we report that PACAP induces the expression of regulator of calcineurin 1 (RCAN1, also known as DSCR1), which is abnormally expressed in the brains of Down syndrome patients. Increased RCAN1 expression is accompanied by activation of the PKA-cAMP response element-binding protein pathways. EMSA and ChIP analyses demonstrate the presence of a functional cAMP response element in the RCAN1 promoter. Moreover, we show that PACAP-dependent neuronal differentiation is significantly disturbed by improper RCAN1 expression. Our data provide the first evidence of RCAN1, a Down syndrome-related gene, as a novel target for control of the neurotrophic function of PACAP.</P>

Preparation and Gas Permeation Properties of Silica Membranes on Porous Stainless Steel-Tube Supports

Hye Ryeon Lee,Bongkuk Seo 한국막학회 2014 멤브레인 Vol.24 No.3

본 연구에서 고투과도를 갖는 실리카 분리막은 콜로이달 실리카 졸과 고분자형 실리카 졸 두 가지를 DRFF법과SRFF법으로 다공성 금속 지지체 위에 코팅하여 제조되었다. 실리카 졸은 졸-겔법으로 테트라에톡시실란(TEOS)에 의하여 제조되었고, 각각의 졸은 동적광산란법(DLS), 전계방사 주사전자현미경(FE-SEM), 질소 흡착법 등을 이용하여 그 특성을 평가하였다. 다공성 금속 지지체위에 콜로이달 실리카 졸로 중간층을 형성하여 치밀한 구조의 실리카 층을 형성한 후 그 위에 분리층으로 고분자형 실리카 졸을 코팅하여 핀홀을 줄이는 방법으로 기체분리용 분리막을 제조하였다. FE-SEM으로 분리막의코팅 층을 분석한 결과 분리층은 중간층보다 침밀한 구조를 가지고 있음을 확인하였고 기체투과 결과 수소 투과도 (6.63-9.21) × 10-5 mol⋅m-2⋅s-1⋅Pa-1 분포를 보였다. Silica membranes with high permeability were prepared using colloidal and polymeric silica sols on a porous stainless steel-tube support by a DRFF and SRFF method. Silica sols were derived with tetraethylorthosilicate (TEOS) by sol-gel method and analyzed with DLS, FE-SEM, and N2 adsorption. The coating of the intermediate layer with colloidal silica sol on the stainless steel-tube support led to a denser surface morphology of the membrane along with a considerable reduction in the number of surface defect. As the polymeric silica sol enclosed the colloidal silica sol with spherical par-ticles during the SRFF method, the separation-layer-coated silica membrane showed a denser surface than the intermediate layer. Moreover, the silica membranes showed high hydrogen gas permeability of (6.63-9.21) × 10-5 mol⋅m-2⋅s-1⋅Pa-1 with low H2/N2 perm-selectivity (2.9-3.1) at room temperatures.

The Efficacy of SDH Immunohistochemical(IHC) Stain for the Screening of Hereditary Pheochromocytoma-Paraganglioma(PPGL)

Hye Ryeon Choi,Sang-Wook Kang,Sun Hyung Choi,Soon Min Choi,Jin Kyong Kim,Cho Rok Lee,Jandee Lee,Jong Ju Jeong,Kee-Hyun Nam,Woong Youn Chung,Ja Seung Koo 대한외과학회 2020 대한외과학회 학술대회 초록집 Vol.2020 No.11

Celebrating 40 years of Korean American Communication Scholarship

Hye-ryeon Lee 한국언론학회 2017 Asian Communication Research Vol.14 No.2

A Cross-Cultural Analysis of the Effect of Social Media Use on Psychological Well-Being : The Role of Motivation, Social Support, and Self-Esteem

Hye-ryeon Lee,Hye Eun Lee,Jounghwa Choi 한국소통학회 2017 한국소통학보 Vol.16 No.2

소셜미디어는 사회적 상호작용의 중요한 부분이 되고 있다. 소셜미디어가 심리적 안녕감에 미치는 영향을 이해하기 위해서는 소셜미디어를 이용하는 개인의 동기를 살펴보는 것이 중요하다. 개인들이 소셜미디어 이용에서 무엇을 추구하는지에 따라 이들의 소셜미디어 이용 정도 뿐만 아니라 그에 따른 심리적 결과 또한 달라질 수 있기 때문이다. 이에 본 연구는 미국(N= 564)과 한국(N= 565)의 대학생을 대상으로 한 설문조사를 통해 소셜미디어 이용동기와 심리적 안녕감 간의 관계를 탐색했다. 더불어 이러한 관계에서 문화적 차이가 나타나는지를 한국과 미국의 데이터를 비교하여 고찰했다. 연구결과, 소셜미디어 이용동기가 소셜미디어 이용(즉, 소셜미디어 사이트 이용 개수)에 미치는 영향은 동기의 종류에 따라 다르게 나타났다. 또한 소셜미디어는 두 가지 매개변인 - 사회적 지지와 자아 존중감 - 을 통해 심리적 안녕감에 영향을 미치는 것으로 나타났다. 이러한 관계의 양태는 미국과 한국에서 차이를 보여, 문화가 이 관계에서 중요한 영향력을 행사함을 제시한다. 이러한 결과가 제시하는 함의 또한 논의되고 있다. Social media has become an important part of social interaction. To understand how social media influences psychological well-being, it is important to examine the motivations behind how people use social media. What individuals seek to gain from social media may influence not only the nature and extent of their use of social media but also the type of psychological outcomes they obtain from it. The present study used survey data from the U.S. (N=564) and Korea (N=565) to investigate cross-cultural differences in the relationship between psychological well-being and six different motivations and outcomes of social media use. The study further investigated cross-cultural differences in the relationship between psychological well-being and social media use by comparing American and Korean college students. The results showed that different motivations exerted varying levels of influence on the number of social media sites used. Moreover, the number of social media sites used was shown to influence psychological well-being through two different outcomes: perceived social support and self-esteem. The pattern of the relationship also differed for the U.S. and Korea, thus demonstrating that culture exerts an influence on the observed relationship. The implications of these findings are discussed.