Characteristics of a-GaN films and a-AlGaN/GaN heterojunctions prepared on r-sapphire by two-stage growth process

Polyakov, A. Y.,Jang, Lee-Woon,Smirnov, N. B.,Govorkov, A. V.,Kozhukhova, E. A.,Yugova, T. G.,Reznik, V. Y.,Pearton, S. J.,Baik, Kwang Hyeon,Hwang, Sung-Min,Jung, Sukkoo,Lee, In-Hwan American Institute of Physics 2011 JOURNAL OF APPLIED PHYSICS - Vol.110 No.9

<P>The electrical properties, presence of deep electron and hole traps and photoluminescence spectra were measured for undoped a-GaN films grown by metal-organic chemical vapor deposition (MOCVD) in a two-stage process using a high V/III ratio at the first stage and low V/III ratio at the second stage. Growth was performed on r-sapphire substrates with a high temperature GaN nucleation layer. The films showed a full width at half maximum of 450-470 arcseconds for the (11-20) x-ray rocking curve with little anisotropy with respect to the sample rotation around the growth direction. The stacking fault (SF) density determined by selective etching was similar to 5 x 10(4) cm(-1). The residual donor concentration was 10(14)-10(15) cm(-3), with a very low density (2.5 x 10(13) cm(-3)) of electron traps located at E-c - 0.6 eV, which are believed to be one of the major non-radiative recombination centers in nonpolar GaN. Consequently, the films showed a high intensity of bandedge luminescence with negligible contribution from defect bands associated with SFs. In contrast to previously studied nonpolar GaN films, the a-GaN layers showed a high concentration of gallium-vacancy-related acceptors near E-v + 1 eV and a strong yellow luminescence band, both indicating that growth conditions were effectively N-rich. a-AlGaN/GaN heterojunctions with thin heavily Si doped AlGaN barriers made on a-GaN substrates showed two-dimensional electron gas (2DEG) concentrations of 1.2 x 10(13) cm(-3), with 2DEG mobility of 80 cm(2)/Vs. Capacitance-voltage profiling of Schottky diodes on these HJs suggest that the 2DEG is fully depleted by the built-in voltage of the Schottky diode. (C)2011 American Institute of Physics. [doi: 10.1063/1.3658026]</P>

The Role of Adenosine Receptors on Acetylcholine Release in the Rat Striatum

Do Kyung Kim,Hyeon A Kim,Bong Kyu Choi 대한생리학회-대한약리학회 1997 The Korean Journal of Physiology & Pharmacology Vol.1 No.1

<P> As it has been reported that the depolarization induced acetylcholine (ACh) release is modulated by activation of presynaptic A<SUB>1</SUB> adenosine heteroreceptor and various evidence suggest that indicate the A<SUB>2</SUB> adenosine receptor is present in the striatum, this study was undertaken to delineate the role of adenosine receptors on the striatal ACh release. <P> Slices from the rat striatum were equilibrated with [<SUP>3</SUP>H]choline and then the release amount of the labelled product, [<SUP>3</SUP>H]ACh, which was evoked by electrical stimulation (rectangular pulses, 3 Hz, 2 ms, 24 mA, 5 Vcm<SUP>-1</SUP><SUB>, </SUB>2 min), was measured, and the influence of various agents on the evoked tritium outflow was investigated. And also, quantitative receptor autoradiography and drug-receptor binding assay were performed in order to confirm the presence and characteristics of A<SUB>1</SUB> and A<SUB>2</SUB> adenosine receptors in the rat striatum. <P> Adenosine (10∼100 ㄍM) and N<SUP>6</SUP>-cyclopentyladenosine (CPA, 1∼100 ㄍM) decreased the [<SUP>3</SUP>H]ACh release in a dose-dependent manner without changing the basal rate of release in the rat striatum. The reducing effects of ACh release by adenosine and CPA were abolished by 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 2 ㄍM), a selective A<SUB>1</SUB> adenosine receptor antagonist, treatment. The effect of adenosine was potentiated markedly by 3,7-dimethyl-1-propargylxanthine (DMPX, 10 ㄍM), a specific A<SUB>2</SUB> adenosine receptor antagonist. 2-P-(2-carboxyethyl)phenethylamimo-5 -N-ethylcarboxamidoadenosine hydrochloride (CGS-21680C), in concentrations ranging from 0.01 to 10 ㄍM, a recently introduced potent A<SUB>2</SUB> adenosine receptor agonist, increased the [<SUP>3</SUP>H]ACh release in a dose related fashion without changing the basal rate of release. These effects were completely abolished by DMPX (10 ㄍM). In autoradiography experiments, [<SUP>3</SUP>H]2-chloro-N<SUP>6</SUP>-cyclopentyladenosine ([<SUP>3</SUP>H]CCPA) bindings were highly localized in the hippocampus and the cerebral cortex. Additionally, lower levels of binding were found in the striatum. However, [<SUP>3</SUP>H]CGS-21680C bindings were highly localized in the striatal region with the greatest density of binding found in the caudate nucleus and putamen. Lower levels of binding were also found in the nucleus accumbens and olfactory tubercle. In drug-receptor binding assay, binding of [<SUP>3</SUP>H]CCPA to A<SUB>1</SUB> adenosine receptors of rat striatal membranes was inhibited by CPA (K<SUB>i</SUB> = 1.6 nM) and N-ethylcarboxamidoadenosine (NECA, K<SUB>i</SUB> = 12.9 nM), but not by CGS-21680C (K<SUB>i</SUB> = 2609.2 nM) and DMPX (K<SUB>i</SUB> = 19,386 nM). In contrast, [<SUP>3</SUP>H]CGS-21680C binding to A<SUB>2</SUB> adenosine receptors was inhibited by CGS-21680C (K<SUB>i</SUB> = 47.6 nM) and NECA (K<SUB>i</SUB> = 44.9 nM), but not by CPA (K<SUB>i</SUB> = 2099.2 nM) and DPCPX (K<SUB>i</SUB> = 19,207 nM). <P> The results presented here suggest that both types of A<SUB>1</SUB> and A<SUB>2</SUB> adenosine heteroreceptors exist and play an important role in ACh release in the rat striatal cholinergic neurons.

A Study on Enterovirus Genotypes in Busan, Korea from 2017 to 2022

Nam-Ho Kim,Young-A Jung,Hyeon-Jeong Kwon,Han-Nwi You,이승주 대한미생물학회 2023 Journal of Bacteriology and Virology Vol.53 No.2

Human enteroviruses (HEV) are pathogens that cause a wide variety of clinicalillness such as a hand-foot-mouth disease, herpangina, skin rash, encephalitis,aseptic meningitis and even death in young children. This study was aimed toinvestigate the prevalence of HEV infection in young children in Busan, Korea andanalyze the various genotypes of enterovirus. We collected the stool, throat swaband cerebrospinal fluid samples from admitted pediatrics from 2017 to 2022. HEV detection and genotype identification were performed by real-time RT-PCRand RT-PCR and phylogenetic trees were constructed by neighbor-joining methodcompared with reference strains. A total of 1,412 samples were collected and128 cases (9.1%) were detected. Based on partial VP1 sequencing, a total 93enterovirus isolates were resolved into 4 genotypes and 18 serotypes; Humanenterovirus A, B, D (HEV-A, B, D) and Rhinovirus. HEV-A is 30 isolates included 7serotypes, HEV-B is 63 isolates included 10 serotypes, HEV-D is 1 isolates included1 serotypes and Rhinovirus is 5 isolated included 3 serotypes. Prevalent serotypewas coxsakievirus A10 in 2017, coxsakievirus B5 in 2018, Echovirus 30 in 2019. Thetemporal distribution of HEV epidemics in Busan showed a remarkable seasonalpattern, from June to September. The genotypes of circulating enteroviruseswere diverse from year to year and most of the sequences circulated in Busanshowed homology with reference sequences in neighboring countries such asChina. Monitoring and genotyping of these enteroviruses will play a role inpreventing the development of serious diseases caused by enteroviruses andgenotype analysis can be used as a basic data for epidemiological studies.

소화기 ; 대전 지역에서 급성 A형 간염의 유전자형에 따른 임상 특성 고찰

이영우 ( Young Woo Lee ),양현웅 ( Hyeon Woong Yang ),이진아 ( Jin A Lee ),윤기호 ( Ki Ho Yun ),양성은 ( Seong Eun Yang ),이민지 ( Min Ji Lee ),박세영 ( Se Young Park ),김새희 ( Sae Hee Kim ),이향이 ( Hyang Ie Lee ),이윤정 ( Yun Ju 대한내과학회 2011 대한내과학회지 Vol.80 No.5

목적: B형 간염이나 C형 간염 등은 유전자형에 따른 차이가 알려져 있지만, 국내에서 증가하는 IIIA 유전자형과 기존의 IA 유전자형에 의한 간염의 차이가 거의 알려진 바 없다. 따라서 대전 지역에서 발생한 급성 A형 간염의 유전자형에 따른 차이를 알고자 한다. 방법: 2009년 11월부터 2010년 6월까지 급성 A형 간염으로 진단되면서 유전자형이 확인된 81명의 환자를 대상으로 임상적 소견들과 검사실 소견들을 전향적으로 연구하였다. 결과: 평균 나이는 32.6±7.4세이며, 평균 입원 기간은 7.7±2.4일이었다. 직업은 서비스직, 사무직 그리고 교육직이 가장 많았다. 유전자형 간의 급성 간염에 따른 증상들의 종류는 별다른 차이가 없었다. 유전자형에 따른 증상의 빈도는 IIIA 유전자형에서 구토와 설사가, IA 유전자형에서는 복통과 피부 반점이 상대적으로 많았다. 검사실 소견에서는 IIIA 유전자형에서 헤모글로빈의 평균, CRP 평균, AST 최대 수치 평균은 상대적으로 유의하게 높았다. 그리고 AST와 ALT 및 총 빌리루빈 최대 수치들과 INR의 수치가 IIIA 유전자형에서 상대적으로 높게 분포하는 경향을 보였다. 결론: 대전 지역에서 유행하는 급성 A형 간염에서 IIIA 유전자형에 따른 급성 간염은 기존의 IA 유전자형과 차이가 있을 것으로 보이며, 다기관 연구를 통한 심도 깊은 연구가 필요하겠다. Background/Aims: Acute viral hepatitis A is a major health problem in Korea and the influx of genotype IIIA is thought to be one reason. We examined the differences in the clinical characteristics and laboratory findings of genotypes IA and IIIA in Daejeon. Methods: From November 2009 to June 2010, 81 patients positive for IgM anti-HAV were enrolled prospectively. The hepatitis A was genotyped using real-time polymerase chain reaction. The clinical characteristics and laboratory results were compared on the Results: The mean patient age was 32.6±7.4 years. The mean hospitalization was 7.7±2.4 days. The patient occupation varied. Clinically, vomiting and diarrhea were relatively more prevalent in genotype IIIA than in IA. Abdominal pain and skin spots were relatively more prevalent in genotype IA than in IIIA. The hemoglobin, peak aspartate aminotransferase (AST) level, and C-reactive protein were statistically higher in genotype IIIA than in IA. The distributions of the peak AST, alanine aminotransferase (ALT) and total bilirubin values tended to be perched in genotype IIIA than in IA. The international normalized ratio (INR) tended to be slightly prolonged in genotype IIIA than in IA. Conclusions: Recently, genotype IIIA of acute viral hepatitis A has become prevalent in Daejeon. Hepatitis A genotype IIIA probably causes worse laboratory abnormalities than genotype IA.

인진과 황련 추출물의 췌장암 세포주 MIA PaCa-2에 대한 세포사멸 효과

주현아,배현진,황충연,Joo, Hyun-A,Bae, Hyeon-Jin,Hwang, Chung-Yeon 대한한방안이비인후피부과학회 2014 한방안이비인후피부과학회지 Vol.27 No.4

Purpose : The purpose of this study is to investigate the effect of ARTEMISIAE CAPILLARIS HERBA and COPTIDIS RHIZOMA Extracts on cell death in pancreatic cancer cells. Method : Human-derived pancreatic cancer cell line, MIA PaCa-2 cells were treated by Prescription A with various concentrations and the cytotoxicity was determined by MTT assay. To investigate the effects of Prescription A on pancreatic cancer cells, the staining of Annexin V/PI, cell cycle arrest, nuclear chromatin condensation and the production of reactive oxygen species (ROS) were examined. The effect of Prescription A's effective components, ARTEMISIAE CAPILLARIS HERBA and COPTIDIS RHIZOMA Extracts on cell death were also observed. Results : The viability of MIA PaCa-2 cells treated with Prescription A were decreased in a dose dependent manner. Prescription A induced cell death in MIA PaCa-2 cells as shown by result of Annexin V/PI double staining, chromatin condensation and cell cycle arrest. In addition, production of ROS was increased by Prescription A treatment, suggesting that ROS induced by Prescription A mediated cell death. Furthermore, Prescription A's effective components, ARTEMISIAE CAPILLARIS HERBA and COPTIDIS RHIZOMA Extracts were also induced apoptosis of MIA PaCa-2 cells through ROS production. Conclusion : These results suggest that Prescription A's effective components, ARTEMISIAE CAPILLARIS HERBA and COPTIDIS RHIZOMA Extracts induced death of MIA PaCa-2 through ROS production.

The association between prion proteins and Aβ1-42 oligomers in cytotoxicity and apoptosis

Hyeon, Jae Wook,Kim, Su Yeon,Park, Jun Sun,Choi, Bo Yeong,Lee, Sol Moe,Ju, Young Ran,An, Seong Soo A.,Kim, Chi-Kyeong Elsevier 2012 Biochemical and biophysical research communication Vol.424 No.2

<P>Misfolding of prion protein (PrP to PrPSc) can cause neurodegenerative prion diseases. As a glycosylphosphatidylinositol (GPI)-anchored membrane protein, the normal form of PrP (PrPC) can function as a receptor for ligands in the extracellular space. PrPC was suggested to be involved in memory, synaptic neuronal communication, and anti-oxidation as a neuroprotective agent. The recently identified interaction between PrPC and Aβ(1-42) oligomers suggested another role for PrP as a receptor for Aβ(1-42) oligomers, thereby influencing cytotoxicity and apoptosis. Here, the association between PrPC and Aβ(1-42) oligomers was investigated by visualizing protein localization in neuronal cells by immunocytochemistry. Aβ(1-42) oligomer-induced cytotoxicity was tested in respective expressions of PrPC by using mouse neuroblastoma-2a (N2a) cells, the prion protein overexpressed cells (L2-2B1), and a Prnp-null mouse hippocampal cell line (HpL 3-4). Moreover, apoptotic proteins such as caspase-8 were used to assess the effect of PrPC on Aβ(1-42) oligomer-mediated apoptosis. In L2-2B1 and HpL 3-4 cells, the difference in the cytotoxicity of Aβ(1-42) oligomers could be clearly distinguished. In addition, Aβ(1-42) oligomers induced mitochondria dysfunction, reactive oxygen species (ROS) generation, and calcium influx PrPC-dependently. Apoptosis, related to mitochondria dysfunction, was further investigated to determine the cytotoxic pathway; the results suggest that PrPC could be involved in both the intrinsic and extrinsic apoptotic pathways. Finally, cells with abundant PrPC expression seemed to be more susceptible to Aβ(1-42) oligomer toxicity, suggesting the importance of the level of PrPC expression in the induction of apoptosis.</P>

In-Package Atmospheric Cold Plasma Treatment for Microbiological Safety and Preservation of Grape Tomatoes

Si Hyeon Roh,Brendan A. Niemira,Sea C. Min 한국산업식품공학회 2016 학술대회 및 심포지엄 Vol.2016 No.10

Effects of dielectric barrier discharge atmospheric cold plasma (DACP) treatment on the inhibition of Salmonella and the storability of grape tomato were investigated. Grape tomatoes, with or without inoculation with a cocktail of three strains of Salmonella (~8 log CFU/g tomato), were packaged in a polyethylene terephthalate commercial clamshell container and cold plasma-treated at 35 kVat 1.1 kHz for 3 min using an DACP treatment system equipped with a pin-type high-voltage electrode. DACP treatment resulted in ~1 log CFU/tomato reduction of Salmonella, irrespectively of the size of container (316, 595vs. 758 cm3), the number of grape tomatoes in the container (3, 7, vs. 11), and the position of the tomato in the container(P > 0.05).Rolling integrated during treatment significantly increased the Salmonella reduction rates to 3.1±0.3 and 3.3±0.8 log CFU/tomato in the single-layer and double-layer configurations of the tomato samples in the container (992 cm3), respectively. Rolling-adopted DACP initially reduced the number of total mesophilic aerobes and yeast and molds in the double layer configuration of tomato samples by 1.3±0.3 and 1.5±0.2 log CFU/tomato, respectively, without altering the color and firmness of the tomatoes. The growth of Salmonella, total aerobes, and yeast and molds on DACP-treated grape tomatoes was effectively prevented during storage at 10 °C. DACP treatment did not influence the tomato color index (a*/b*), firmness, weight loss, pH, total soluble solid content, and lycopene concentration of grape tomatoes at 10 and 25 °C (P> 0.05). DACP treatment holds promise as a post-packaging process for improving microbial safety against Salmonella and storability of fresh grape tomatoes.

Losartan Reduces Remodeling and Apoptosis in an Adriamycin-Induced Cardiomyopathy Rat Model

Kim Hyeon A,김관창,Lee Hyeryon,홍영미 대한심장혈관흉부외과학회 2023 Journal of Chest Surgery (J Chest Surg) Vol.56 No.5

Background: The use of Adriamycin (ADR), also known as doxorubicin, as a chemotherapy agent is limited by its detrimental adverse effects, especially cardiotoxicity. Recent studies have emphasized the crucial role of angiotensin II (Ang-II) in the development of ADR-induced cardiomyopathy. This study aimed to explore the potential cardioprotective effects of losartan in a rat model of ADR-induced cardiomyopathy. Methods: Male Sprague-Dawley rats were randomly divided into 3 groups: a control group (group C), an ADR-treated group (ADR 5 mg/kg/wk for 3 weeks via intraperitoneal injections; group A), and co-treatment of ADR with losartan group (same dose of ADR and losartan; 10 mg/kg/day per oral for 3 weeks; group L). Western blot analysis was conducted to demonstrate changes in brain natriuretic peptide, collagen 1, tumor necrosis factor (TNF)-α, interleukin-6, matrix metalloproteinase (MMP)-2, B-cell leukemia/lymphoma (Bcl)- 2, Bcl-2-associated X (Bax), and caspase-3 protein expression levels in left ventricular (LV) tissues from each group. Results: Losartan administration reduced LV hypertrophy, collagen content, and the expression of pro-inflammatory factors TNF-α and MMP-2 in LV tissue. In addition, losartan led to a decrease in the expression of the pro-apoptotic proteins Bax and caspase-3 and an increase in the expression of the anti-apoptotic protein Bcl-2. Moreover, losartan treatment induced a reduction in the apoptotic area compared to group A. Conclusion: In an ADR-induced cardiomyopathy rat model, co-administration of ADR with losartan presented cardioprotective effects by attenuating LV hypertrophy, pro-inflammatory factors, and apoptosis in LV tissue.

Correction: Electrochemical and electrocatalytic reaction characteristics of boron-incorporated graphene <i>via</i> a simple spin-on dopant process

Jang, A.-Rang,Lee, Young-Woo,Lee, Sang-Seok,Hong, John,Beak, Seong-Ho,Pak, Sangyeon,Lee, Juwon,Shin, Hyeon Suk,Ahn, Docheon,Hong, Woong-Ki,Cha, SeungNam,Sohn, Jung Inn,Park, Il-Kyu The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.17

<P>Correction for ‘Electrochemical and electrocatalytic reaction characteristics of boron-incorporated graphene <I>via</I> a simple spin-on dopant process’ by A-Rang Jang <I>et al.</I>, <I>J. Mater. Chem. A</I>, 2018, DOI: 10.1039/c7ta09517a.</P>

소피 칼의 작품 『시각장애인들Aveugles』에 나타난 상호텍스트성 연구

김현아 ( Kim Hyeon-a ) 한국프랑스문화학회 2020 프랑스문화연구 Vol.46 No.1

Nous allons mettre en évidence l’intertexualité dans Aveugles de Sophie Calle. Ce travail invite à réfléchir à l’univers de Sophie Calle qui a créé son identité artistique en utilisant la photographie et le texte. Ceci nous permettra aussi de comprendre le courant de l’art postmoderne qui a une frontière ténue entre le réel et le fictif, la littérature et l’art. Tout d’abord, nous allons découvrir l’image mentale des aveugles à travers leurs histoires. Sophie Calle a demandé à des aveugles de naissance l’image qu’ils se font de la beauté. Ils décrivent une “image de la beauté “se trouvant dans des figures ou des vues harmonieuses, qui leur inspireraient le sentiment d’amour. La plupart des images qu’ils imaginent belles sont en rapport avec la vision, mais certains privilégient d’autres sens et disent par exemple que la douceur du toucher leur plaît. Il est aussi remarquable que des malvoyants puissent apprendre à identifier des images complexes à travers l’ouïe. Par ailleurs, Sophie Calle a demandé à des personnes ayant subitement perdu la vue de décrire ce qu’ils ont vu pour la dernière fois. Ils se souviennent bien de leur dernière vision, puisque lors d’un choc la scène perçue se cristallise grâce à la norépinephrine, un neuromédiateur sécrété par l’amygdale qui est située près de l’hippocampe. Les images que ces aveugles imaginent sont représentées à travers des textes, des inscriptions en braille et des photographies. La manière dont ces média se juxtaposent attire les spectateurs. Ils seraient alors fascinés par l’effet de réel grâce au texte décrit dans le temps présent et à la photographie présentée comme preuve. De plus, le désir des aveugles de voir serait comblé par le processus de la création artistique. Comme le souligne Sigmund Freud, la pulsion de la répétition semble fonctionner comme un mécanisme pour sublimer leur sentiment de perte. Mais l’image que les aveugles imaginent ne correspond pas au texte et à la photographie. Cet écart laisse aux spectateurs la liberté de créer leur propre texte. Le spectateur se trouve par exemple confronté à la photographie d’un aveugle regardant des monochromes, et à des textes où des aveugles ont décrit leurs perceptions issues de l’observation de monochromes de grands artistes contemporains. Ainsi Aveugles n’est pas une oeuvre achevée mais un art conceptuel qui ne cesse de créer un nouveau ‘texte’. On retrouve cette caractéristique dans le ‘nouveau roman’, mouvement littéraire français qui fait suite à la «La mort de l’auteur» de Roland Barthes qui lui-même avait mis en valeur le sens polysémique du «texte». Comme dans la réflexion de Jacques Derrida, l’intertexualité forme des milliers de réseaux à portée du spectateurs pour redonner du sens à leur existence et éviter la présomption de la nature de la vérité.