Photocatalyst-free Photoredox Arylation of Quinoxalin-2(1H)-Ones with Aryldiazo Sulfones

정혜임,이주희,김대영 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.8

High Performance Charge Pump Converter with Integrated CMOS Feedback Circuit

정혜임,박정웅,최호용,김남수 한국전기전자재료학회 2014 Transactions on Electrical and Electronic Material Vol.15 No.3

In this paper, an integrated low-voltage control circuit is introduced for a charge pump DC-DC boost converter. By exploiting the advantage of the integration of the feedback control circuit within CMOS technology, the chargepump boost converter offers a low-current operation with small ripple voltage. The error amplifier, comparator, andoscillator in the control circuit are designed with the supply voltage of 3.3 V and the operating frequency of 1.6~5.5MHz. The charge pump converter with the 4 or 8 pump stages is measured in simulation. The test in the 0.35 μmCMOS process shows that the load current and ripple ratio are controlled under 1 mA and 2% respectively. Theoutput-voltage is obtained from 4.8 ~ 8.5 V with the supply voltage of 3.3 V.

Integrated Current-Mode DC-DC Buck Converter with Low-Power Control Circuit

정혜임,이찬수,김남수 한국전기전자재료학회 2013 Transactions on Electrical and Electronic Material Vol.14 No.5

A low power CMOS control circuit is applied in an integrated DC-DC buck converter. The integrated converter is composed of a feedback control circuit and power block with 0.35 μm CMOS process. A current-sensing circuit is integrated with the sense-FET method in the control circuit. In the current-sensing circuit, a current-mirror is used for a voltage follower in order to reduce power consumption with a smaller chip-size. The N-channel MOS acts as a switching device in the current-sensing circuit where the sensing FET is in parallel with the power MOSFET. The amplifier and comparator are designed to obtain a high gain and a fast transient time. The converter offers wellcontrolled output and accurately sensed inductor current. Simulation work shows that the current-sensing circuit is operated with an accuracy of higher than 90% and the transient time of the error amplifier is controlled within 75μsec. The sensing current is in the range of a few hundred μA at a frequency of 0.6~2 MHz and an input voltage of 3~5 V. The output voltage is obtained as expected with the ripple ratio within 1%.

Enantioselective Organocatalytic Mannich Reaction and Fluorination Sequence of Pyrazolones to Isatin-derived Ketimines

정혜임,박진화,김대영 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.12

An efficient asymmetric synthesis of oxindole-pyrazolone adducts via organocatalytic Mannich reaction of 1-phenyl-1H-pyrazol-5(4H)-ones with ketimine derivatives derived from isatins, followed by sequential electrophilic fluorination, has been developed. This approach offers a facile way to prepare chiral 3-amino-3-(4-fluoropyrazol-4-yl)-substituted oxindole derivatives with a wide range of functional group tolerance.

Characterization of cell death in Escherichia coli mediated by XseA, a large subunit of exonuclease VII

정혜임,Junwei Liang,정유나,임동빈 한국미생물학회 2015 The journal of microbiology Vol.53 No.12

Exonuclease VII (ExoVII) of Escherichia coli is a single strandspecific DNA nuclease composed of two different subunits: the large subunit, XseA, and the small subunit, XseB. In this study, we found that multicopy single-stranded DNAs (msDNAs), Ec83 and Ec78, are the in vivo substrates of ExoVII; the enzyme cuts the phosphodiester bond between the fourth and fifth nucleotides from the 5 end. We used this msDNA cleavage to assess ExoVII activity in vivo. Both subunits were required for enzyme activity. Expression of XseA without XseB caused cell death, even though no ExoVII activity was detected. The lethality caused by XseA was rescued by surplus XseB. In XseA-induced death, cells were elongated and multinucleated, and their chromosomes were fragmented and condensed; these are the morphological hallmarks of apoptotic cell death in bacteria. A putative caspase recognition sequence (FVAD) was found in XseA, and its hypothetical caspase product with 257 amino acids was as active as the intact protein in inducing cell death. We propose that under ordinary conditions, XseA protects chromosome as a component of the ExoVII enzyme, but in some conditions, the protein causes cell death; the destruction of cell is probably carried out by the amino terminal fragment derived from the cleavage of XseA by caspase-like enzyme.

Thiourea-catalyzed 1,5-Hydride Transfer and Cyclization Sequences: Synthesis of Tetrahydroquinoline Derivatives

정혜임,윤태호,김대영 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.4

북한문제분석 제5호 : 북한 주민의 인권현황과 우리의 대응 ; 발표 2 - 북한여성인권의 현주소

정혜임 단국대학교 정책과학연구소 1999 북한 주민의 인권현황과 우리의 대응 Vol.- No.-

2배체 대장균의 제조와 그 특성

정혜임,임동빈,Jung, Hyeim,Lim, Dongbin 한국미생물학회 2016 미생물학회지 Vol.52 No.4

대장균에서 6개의 Leu 코돈중 가장 흔한 코돈은 CUG이다. 이 코돈을 인식하는 tRNA는 4개의 유전자에 의해 합성되는데, leuPQV와 leuT 2개의 locus로 나누어져 있다. 이 CUG를 인식하는 모든 tRNA가 결핍된 균주를 만들기 위해, 우선 leuPQV가 삭제된 균주(${\Delta}leuPQV$)와, leuT의 anticodon CAG를 GAG로 돌연변이시킨 균주[$Km^R$, $leuT^*$(GAG)]를 각각 만들었다. 이 두 돌연변이 유전자를 모으기 위해 ${\Delta}leuPQV$ 균주를 recipient로, $leuT^*$(GAG) 균주를 donor로하는 transduction을 수행한 결과, 콜로니 크기가 큰 것과 작은 것 두 종류의 transductant를 얻었다. PCR 후 염기서열 분석 결과 큰 콜로니는 예측한 recombinant로 판명됐으나, 작은 콜로니는 donor와 recipient 염색체 간의 상호교환재조합(reciprocal recombination)으로는 설명이 되지 않는, 돌연변이 유전자[$leuT^*$(GAG)]와 야생형 유전자(leuT(CAG)]를 모두 가진 균주로 밝혀졌다. 이 heterozygous diploid는 광학현미경으로 관찰시 세포의 형태와 크기에서 특이점이 발견되지 않았으나, 영양배지에서 야생형에 비해 생장이 한참 느리면서, 선형생장곡선(linear growth curve)이라는 예측하지 못한 생장특성을 보였다. 이 2배체 균주는 선택배지에서는 항상 작은 균일한 콜로니를 형성하였으나, 배지에 선택항생제 없을 경우, $leuT^*$(GAG) 유전자형 세포와 leuT(CAG) 유전자형 세포로 분리가 일어났다. 우리의 결과를 종합해볼 때, 이 2배체 균주는, $leuT^*$(GAG)와 leuT(CAG) 부분만 2배체로 갖는 부분이배체(merodiploid)라기 보다는, $leuT^*$(GAG)와 leuT(CAG)가 서로 다른 염색체에 있는 완전이배체라는 모델을 지지했다. 우리는 이러한 2배체가 어떻게 생성되었으며, 어떻게 분리되는지, 또 이 균주는 왜 선형생장곡선을 보이는지 등에 대한 모델을 토론하였다. Among 6 leu codons, CUG is the most frequently used codon in E. coli. It is recognized by leu-tRNA(CAG) encoded by four genes scattered on two chromosomal loci (leuT and leuPQV ). In the process of constructing a strain with no functional leu-tRNA (CAG) gene on chromosome, we made two mutant strains separately, one on leuPQV locus (${\Delta}leuPQV$), and the other on leuT locus [$leuT^*$(GAG)], where the anticodon of leuT was changed from CAG to GAG, thereby altering its recognition codon from CUG to CUC. We attempted to combine these two mutations by transduction using $leuT^*$(GAG) strain as a donor and ${\Delta}leuPQV$ strain as a recipient. Large and small colonies appeared from this transduction. From PCR and DNA sequencing, large colony was confirmed to be the reciprocal recombinant as expected, but the small colonies contained both mutant $leuT^*$(GAG) and wild type leuT (CAG) genes in the cell. This heterozygous diploid strain did not show any unusual morphology under microscopic observation, but, interestingly, it showed a linear growth curve in rich medium with much slower growth rate than wild type cell. It always formed homogenous small colonies in the selection medium, but, when there was no selection, it readily segregated into $leuT^*$(GAG) and leuT (CAG). From these observations, we suggested that the strain with both $leuT^*$(GAG) and leuT (CAG) genes was not a partial diploid (merodiploid), but a full diploid cell having two different chromosomes. We proposed a model explaining how such a heterozygous diploid cell was formed and how and why its growth showed a linear growth curve.

The Construction of Regulatory Network for Insulin-Mediated Genes by Integrating Methods Based on Transcription Factor Binding Motifs and Gene Expression Variations

정혜임,한성균,김상수 한국유전체학회 2015 Genomics & informatics Vol.13 No.3

Type 2 diabetes mellitus is a complex metabolic disorder associated with multiple genetic, developmental and environmental factors. The recent advances in gene expression microarray technologies as well as network-based analysis methodologies provide groundbreaking opportunities to study type 2 diabetes mellitus. In the present study, we used previously published gene expression microarray datasets of human skeletal muscle samples collected from 20 insulin sensitive individuals before and after insulin treatment in order to construct insulin-mediated regulatory network. Based on a motif discovery method implemented by iRegulon, a Cytoscape app, we identified 25 candidate regulons, motifs of which were enriched among the promoters of 478 up-regulated genes and 82 down-regulated genes. We then looked for a hierarchical network of the candidate regulators, in such a way that the conditional combination of their expression changes may explain those of their target genes. Using Genomica, a software tool for regulatory network construction, we obtained a hierarchical network of eight regulons that were used to map insulin downstream signaling network. Taken together, the results illustrate the benefits of combining completely different methods such as motif-based regulatory factor discovery and expression level-based construction of regulatory network of their target genes in understanding insulin induced biological processes and signaling pathways.

The Effects of Preoperative Education on Self-care Knowledge, Self-care Behaviors, and Nursing Outcomes in Patients Undergoing Laparoscopic Cholecystectomy

정혜임,강현욱 한국자료분석학회 2015 Journal of the Korean Data Analysis Society Vol.17 No.2

The purpose of this study was to determine the effects of preoperative nursing education on self-care knowledge, self-care behavior, and nursing outcomes in patients following laparoscopic cholecystectomy. A nonequivalent control group pretest-posttest design was used. Data were collected between July 1 and September 7, 2012 in K university hospital in Korea. The participants who were scheduled to undergo laparoscopic cholecystectomy, were assigned to an experimental group (n=27) or a control group (n=29). After pretests for self-care knowledge, the experimental group was then provided with preoperative education using PowerPoint slides and leaflets on the day before the surgery. On postoperative day (POD) 2, 7 nursing outcomes were administered. On POD 7, the participants self-reported self-care knowledge and self-care behavior. The increase in the self-care knowledge was significantly greater in the experimental group. The levels of self-care behaviors and nursing outcomes except for ambulation were significantly higher in the experimental group. Providing preoperative education to patients undergoing laparoscopic cholecystectomy was effective in improving self-care knowledge, self-care behaviors and nursing outcomes.