Skin corrosion and irritation test of sunscreen nanoparticles using reconstructed 3D human skin model

Choi, Jonghye,Kim, Hyejin,Choi, Jinhee,Oh, Seung Min,Park, Jeonggue,Park, Kwangsik The Korean Society of Environmental Toxicology 2014 환경독성보건학회지 Vol.29 No.-

Objectives Effects of nanoparticles including zinc oxide nanoparticles, titanium oxide nanoparticles, and their mixtures on skin corrosion and irritation were investigated by using in vitro 3D human skin models ($KeraSkin^{TM}$) and the results were compared to those of an in vivo animal test. Methods Skin models were incubated with nanoparticles for a definite time period and cell viability was measured by the 3-(4, 5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide method. Skin corrosion and irritation were identified by the decreased viability based on the pre-determined threshold. Results Cell viability after exposure to nanomaterial was not decreased to the pre-determined threshold level, which was 15% after 60 minutes exposure in corrosion test and 50% after 45 minutes exposure in the irritation test. IL-$1{\alpha}$ release and histopathological findings support the results of cell viability test. In vivo test using rabbits also showed non-corrosive and non-irritant results. Conclusions The findings provide the evidence that zinc oxide nanoparticles, titanium oxide nanoparticles and their mixture are 'non corrosive' and 'non-irritant' to the human skin by a globally harmonized classification system. In vivo test using animals can be replaced by an alternative in vitro test.

Evolution of the surface state in Bi2Se2Te thin films during phase transition

Choi, Hyejin,Kim, Tae Hyeon,Chae, Jimin,Baeck, Juheyuck,Kee, Chul-Sik,Jeong, Kwang-Ho,Jeong, Hong-Sik,Kang, Chul,Cho, Mann-Ho The Royal Society of Chemistry 2015 Nanoscale Vol.7 No.36

Enhancement in thermoelectric properties of Te-embedded Bi₂Te₃ by preferential phonon scattering in heterostructure interface

Choi, Hyejin,Jeong, Kwangsik,Chae, Jimin,Park, Hanbum,Baeck, Juheyuck,Kim, Tae Hyeon,Song, Jae Yong,Park, Jaehun,Jeong, Kwang-Ho,Cho, Mann-Ho Elsevier 2018 Nano energy Vol.47 No.-

<P><B>Abstract</B></P> <P>A comprehensive understanding of the nano-structural effects that cause reduction in thermal conductivity represents important challenges for the development of thermoelectric materials with an improved figure of merit ZT. Bismuth telluride (Bi<SUB>2</SUB>Te<SUB>3</SUB>)-based thermoelectric materials exhibit very low levels of thermal conductivity. In this study, a Te crystal-embedded Bi<SUB>2</SUB>Te<SUB>3</SUB> (Te–Bi<SUB>2</SUB>Te<SUB>3</SUB>) thin film was formed by establishing a specific annealing temperature for a Te-rich Bi/Te multilayered structure. Modulations in structure and composition were observed at the boundaries between the two phases of Te and Bi<SUB>2</SUB>Te<SUB>3</SUB>. Furthermore, the samples contained regularly shaped nanometer-scale Bi<SUB>2</SUB>Te<SUB>3</SUB> single grains. Therefore, we obtained a dramatic ZT value of 2.27 (+ 0.04, − 0.08) at 375 K from the Te–Bi<SUB>2</SUB>Te<SUB>3</SUB> thin film. Finally, we confirmed that interface phonon scattering between the Te–Bi<SUB>2</SUB>Te<SUB>3</SUB> boundaries plays an important role in inter-grain phonon transport, which results in a reduction in the lattice thermal conductivity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Te-Bi<SUB>2</SUB>Te<SUB>3</SUB> nano-grain structure is synthesized by multi-layer deposition and simple annealing process. </LI> <LI> Obtain a dramatic zT value of 2.27 (+ 0.04 − 0.08) at 375 K in Te embedded-Bi<SUB>2</SUB>Te<SUB>3</SUB> thin film. </LI> <LI> The Te-Bi<SUB>2</SUB>Te<SUB>3</SUB> heterojunction has high electrical conductivity and low thermal conductivity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Spore-forming probiotic bacterium Bacillus coagulans influences on the flavor of Gouda cheese using micro-cheese platform

Hyejin Choi,Sangdon Ryu,Daye Mun,Woongji Lee,An Na Kang,Mingeun Kang,Hayoung Kim,Daniel Lee,Sangnam Oh,Younghoon Kim 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10

Bacillus coagulans is a gram-positive, spore-forming and potential probiotic bacterium in food industry. Spore-forming bacteria is enable to survive in the host"s gastrointestinal tract functioning as probiotics that could play a beneficial role in the host health. We evaluated the probiotic characteristics including acid, bile and heat tolerance of B. coagulans SRCM121381 isolated from human breast milk. SRCM121381 showed high resistance to acid and bile, heat tolerance. We employed FIMM (Fermentor for Intestine Microbiota Model) system to evaluate effects of SRCM 121381 on the microbial dynamics in gut environments. SRCM121381 resulted in increased population of Romboutsia and Turicibacter at the genus level, while the abundance of Escherichia decreased significantly. We added SRCM 121381 with starter strains for Gouda cheese using micro-cheese platform and evaluated on the change of cheese flavor. SRCM121381 increased acetic acid (Vinegar) and decreased esters and ketone as undesirable flavor such as bitter taste. Our results propose that potential probiotic bacterium B. coagulans SRCM121381 could be applied on dairy foods as an adjunct starter with flavor productivity.

Rapid drug susceptibility test of Mycobacterium tuberculosis using microscopic time-lapse imaging in an agarose matrix

Choi, Jungil,Yoo, Jungheon,Kim, Ki-jung,Kim, Eun-Geun,Park, Kyung Ock,Kim, Hyejin,Kim, Haeun,Jung, Hyunju,Kim, Taeyoung,Choi, Myungjin,Kim, Hee Chan,Ryoo, Sungweon,Jung, Yong-Gyun,Kwon, Sunghoon Springer-Verlag 2016 Applied microbiology and biotechnology Vol.100 No.5

<P>Tuberculosis (TB) is a major global health problem, and multi-drug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) are spreading throughout the world. However, conventional drug susceptibility test (DST) methods, which rely on the detection of the colony formation on a solid medium, require 1-2 months to the result. A rapid and accurate DST is necessary to identify patients with drug-resistant TB and treat them with appropriate drugs. Here, we used microscopic imaging of Mycobacterium tuberculosis (MTB) immobilized in an agarose matrix for a rapid DST. The agarose matrix, which was molded in a microfluidic chip, was inoculated with MTB, and TB drugs in liquid culture medium diffused throughout the agarose to reach the MTB immobilized in the agarose matrix. After the responses of MTB to drugs were tracked with an automated microscopic system, an image-processing program automatically determined the susceptibility and resistance of MTB to specific doses of TB drugs. The automatic DST system was able to assess the drug susceptibility of various drug-resistant clinical TB strains within 9 days with an accuracy comparable to that of conventional method. Our rapid DST method based on microscopic time-lapse imaging greatly reduces the time required for a DST and can be used to rapidly and accurately treat TB patients.</P>

Snapshot of carrier dynamics from amorphous phase to crystal phase in Sb₂Te₃ thin film

Hyejin Choi,Seonghoon Jung,Min Ahn,Won Jun Yang,Jeong Hwa Han,Hoon Jung,Kwangho Jeong,Jaehun Park,Mann-Ho Cho 한국진공학회 2016 한국진공학회 학술발표회초록집 Vol.2016 No.2

Diagnostic imaging of malignant insulinoma in a dog

Choi, Jihye,Keh, Seoyeon,Kim, Sungsoo,Lee, Su-Hyung,Kim, Hyejin,Choi, Heeyeon,Lim, Younji,Kim, Hyunwook,Kim, Ahyoung,Kim, Dae-Yong The Korean Society of Veterinary Science 2012 大韓獸醫學會誌 Vol.52 No.3

Endocrine test data from a 13-year old intact female Maltese was indicative of the presence of an insulinoma, however ultrasonography identified a pancreatic mass only after 10 months after the first admission. Following identification of both pancreatic tumor and hepatic metastasis on computed tomography (CT), surgical excision of the mass was attempted. However, total excision failed because of tumor adhesion to adjacent large vessels. The pancreatic mass was monitored over the next 25 months via ultrasonography, CT, and positron emission tomography-computed tomography (PET-CT). Histopathological and immunohistochemical data confirmed the diagnosis of insulinoma with hepatic metastasis.

Skin corrosion and irritation test of sunscreen nanoparticles using reconstructed 3D human skin model

Jonghye Choi,Hyejin Kim,Jinhee Choi,Seung Min Oh,Jeonggue Park,Kwangsik Park 환경독성보건학회 2014 환경독성보건학회지 Vol.29 No.-

Objectives : Effects of nanoparticles including zinc oxide nanoparticles, titanium oxide nanoparticles, and their mixtures on skin corrosion and irritation were investigated by using in vitro 3D human skin models (KeraSkinTM) and the results were compared to those of an in vivo animal test. Methods : Skin models were incubated with nanoparticles for a definite time period and cell viability was measured by the 3-(4, 5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide method. Skin corrosion and irritation were identified by the decreased viability based on the pre-determined threshold. Results : Cell viability after exposure to nanomaterial was not decreased to the pre-determined threshold level, which was 15% after 60 minutes exposure in corrosion test and 50% after 45 minutes exposure in the irritation test. IL-1α release and histopathological findings support the results of cell viability test. In vivo test using rabbits also showed non-corrosive and non-irritant results. Conclusions : The findings provide the evidence that zinc oxide nanoparticles, titanium oxide nanoparticles and their mixture are ‘non corrosive’ and ‘non-irritant’ to the human skin by a globally harmonized classification system. In vivo test using animals can be replaced by an alternative in vitro test.

근대 판소리 비평 자료의 검토 - 신문, 잡지를 중심으로 -

최혜진 ( Choi Hyejin ) 판소리학회 2014 판소리연구 Vol.38 No.-

본고는 1900년~1940년 사이에 쓰여진 신문, 잡지의 내용 중 판소리 관련 비평적 인식을 담은 글들을 찾아 소개하는 것이 목적이었다. 기사문, 논평문, 기고글 등을 대상으로 하여 자료 현황을 제시하였다. 그리고 현재까지 약 51편 정도의 자료를 수집할 수 있었다. 이를 통해 당대 판소리에 대한 비평적 인식은 물론 그에 따른 새로운 정보를 얻을 수 있었다.본론에서는 수집된 51개의 자료를 유형별로 정리 제시하고 그 의미를 살펴보았다. 판소리 비평에 대해 명창/광대론, 음악론, 공연론, 이면론, 관객론, 소리학습론, 판소리인식론 등의 유형으로 나눌 수 있으며, 이러한 여러 유형은 당대 판소리에 대한 인식이 매우 다양하고 심도있게 진행되었다는 것을 보여준다. 근대 초기에는 판소리에 대한 부정적인 인식이 있었으나, 1930년대에 이르면 조선의 음악 정체성을 보여주는 것으로 바뀌고, 이와 함께 음악론, 관객론, 이면론 등 관련 이론들이 속속 개진되기 시작했던 것이다.근대 판소리 비평 자료는 많지 않은 양임에도 불구하고 매우 중요한 시사점을 던져 준다. 당대 고민했던 많은 내용들을 통해 결국 판소리의 역할과 위상이 수립되었음을 보여주기 때문이다. 이를 통해 우리는 판소리 문화와 당대의 의식 수준을 가늠하고 미래를 예견할 수 있다. 판소리 관련 자료의 탐색은 이러한 의미에서 판소리사를 재구성할 수 있는 중요한 작업이라고 할 수 있다. This study aimed to find and introduce these critical articles about pansori which were published in newspapers and magazines from 1900 to 1940. The study presented the current status after closely reviewing articles, observations, contributions and others, and until the present, the study has collected approximately 51 pieces of references. Through those references, not only did the study improve understanding on contemporary pansori but also it gained new information on the field.In the body of the research, a total of 51 collected references were categorized by type, and their significances were investigated. In terms of the critiques of pansori, the references were divided into these types such as theory of master singers/performers, theory of music, theory of performance, theory of reality, theory of audience, theory of sound learning, theory of pansori knowledge and others, and all of the types are considered proof for how understanding on contemporary pansori has developed in very much various and profound ways. In the early modern age, negative ideas about pansori were observed and yet, by the time the 1930’s arrived, pansori was regarded to represent the musical identity of the Joseon Dynasty, and consequently, those theories such as the theories of music, audience, reality and others were released only constantly.There are only a few critical references on modern pansori and yet, they are still providing considerably significant implications. The roles and reputations of pansori could have not been established without all those discussions conducted back then. The references and discussions are considered a chance for us to forecast both how people of the old times understood the pansori culture and the future of pansori as well. In the light of that, the study believes that exploring references in connection with pansori is important work to restructure the history of pansori.

유아교사의 직무자율성과 교수창의성의 관계에서 그릿의 매개효과

최혜진(Hyejin Choi),박리나(Reena Park) 한국생태유아교육학회 2023 생태유아교육연구 Vol.22 No.1

본 연구의 목적은 유아교사의 직무자율성과 교수창의성의 관계에서 그릿의 매개효과를 확인하고자 하였다. 이를 위해 G도에 소재하는 유아교육기관에 근무 중인 교사 224명을 대상으로 하였다. 수집된 자료는 SPSS 23.0과 Process macro 4.0을 활용하여 기술통계, 신뢰도 분석, 상관분석 및 매개효과 분석을 실시하였다. 연구결과는 다음과 같다. 첫째, 유아교사의 직무자율성, 그릿, 교수창의성은 모두 서로 간에 정적 상관관계에 있었다. 둘째, 유아교사의 직무자율성은 교수창의성에 정적 영향을 미치며, 그릿이 직무자율성이 교수창의성에 미치는 영향에서 부분매개역할을 하는 것으로 나타났다. 본 연구결과는 교수창의성에 영향을 미칠 수 있는 변인으로서 직무자율성 뿐만 아니라 그릿의 중요성을 확인함으로써 교수창의성 증진을 위한 시사점을 제공하였다. The purpose of this study was to confirm the mediating effect of grit in the relationship between job autonomy and teaching creativity of Early Childhood Teachers in South Korea. Around 224 teachers working in early childhood educational institutions located in Seoul, Gangwon, and Gyeongsang were recruited. Data were subjected to descriptive statistics, reliability analysis, correlation analysis, and mediating effect analysis using SPSS 23.0 and Process macro 4.0. The findings are as follows. First, early childhood teachers’ job autonomy, teaching creativity, and grit were all positively correlated with each other. Second, their job autonomy had a positive effect on teaching creativity, and some aspects of job autonomy were found to affect teaching creativity through grit. The results of this study provide implications for enhancing teaching creativity by confirming the role and importance of grit as well as job autonomy as variables that can affect teaching creativity.