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Rheology of Decamethylceclopentasiloxane (cyclomethicone) W/O Emulsion System
Choi, Min-Hyung,Jeong, So-Ra,Nam, Sang-In,Shim, Sang-Eun,Chang, Yoon-Ho The Polymer Society of Korea 2009 Macromolecular Research Vol.17 No.12
A highly dispersed W/O emulsion of silicone oil (cyclomethicone)/water system was prepared with a nonionic surfactant. The surface and interfacial tension between the oil and water were characterized in terms of the droplet size distribution and viscosity change of the emulsion. When the dispersed phase concentration was relatively high, the viscosity of the emulsion was rapidly increased and the droplet size of the emulsion was decreased. The rheological behavior of the emulsion system showed non-Newtonian and shear thinning phenomena depending upon the content of the dispersed phase. The droplet size of the emulsion was decreased with increasing surfactant content and water concentration. The relative viscosity of the emulsion was better predicted with the Choi-Schowalter model than with the Taylor model. The value of the complex modulus increased with increasing surfactant concentration. The linear viscoelastic region was expanded with a dispersed phase concentration. According to the change in the viscosity, the behavior was classified into three distinct regions: [I] linear viscoelastic, [II] partially viscoelastic, and [III] viscous. The creep/recovery behaviors in each region were characterized.
Choi, Min Seok,Ryu, Jong-Sik,Park, Ha Yan,Lee, Kwang-Sik,Kil, Youngwoo,Shin, Hyung Seon The Royal Society of Chemistry 2013 Journal of analytical atomic spectrometry Vol.28 No.4
<P>Lithium has two naturally occurring isotopes, <SUP>6</SUP>Li and <SUP>7</SUP>Li, with approximate relative abundances of 7.5% and 92.5%, respectively. Due to large Li isotope variations in nature, lithium isotopes have the potential to reveal important information relevant to nuclear technology, biomedicine, astrophysics, and geochemistry. With the advent of multi-collector inductively coupled mass spectrometry (MC-ICP-MS), studies of Li isotopes have largely focused on the analysis of geological materials, with varying degrees of accuracy. However, this technique has often been affected by either baseline interferences or isobaric interferences on mass 6 and 7 during ionization in Ar plasma, which is mainly due to the Li compound with hydrogen gas, and double-charged nitrogen and carbon ions at higher levels of RF power. In this study, we reduced baseline interferences in Ar plasma using a cool plasma (∼800 W) technique with a X-type cone. Lithium was separated using a cation exchange column (BioRad AG50W-X8, 200–400 mesh) with a mixture of 6 N HNO<SUB>3</SUB> and 80% methanol at <0.2 mL min<SUP>−1</SUP> elution speed. The short-term reproducibility of <I>δ</I><SUP>7</SUP>Li values of the NASS-5 seawater standard was 30.55 ± 0.45‰ (2<I>σ</I>, <I>n</I> = 15). Measured <I>δ</I><SUP>7</SUP>Li values of rock and seawater standards ranged from 2.48 to 30.55‰, in good agreements with reported values.</P> <P>Graphic Abstract</P><P>Average <I>δ</I><SUP>7</SUP>Li values of a pure L-SVEC Li solution and one passed through the column were 0.00 ± 0.23‰ (2<I>σ</I>, <I>n</I> = 26) and ¬0.01 ± 0.20 ‰ (2<I>σ</I> , <I>n</I> = 9), respectively, indicating that our chemical separation procedure for Li induces no mass fractionation. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2ja30293d'> </P>
Choi, Joon-Sig,Choi, Min-Ji,Go, Gyeong-Su,Rhee, Byoung-Doo,KimPak, Young-Mi,Bang, In-Seok,Lee, Min-Hyung Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.9
It has been found that a number of diseases are associated with mutations in the mitochondrial DNA. Therapeutic gene delivery to mitochondria has been suggested as a clinical option for these diseases. In this study, we developed a gene carrier to mitochondria by the conjugation of mitochondrial leader peptide (LP) to polyethylenimine (PEI). Mitochondrial LP conjugated PEI (PEI-LP) was synthesized with low molecular weight PEI (2,000 Da, PEI2K). Gel retardation assay showed that PEI2K-LP formed complexes at a 1.0/1 weight ratio. In addition, PEI2K-LP protected DNA from the enzymatic degradation for at least 60 min, while naked DNA was completely degraded within 20 min. PEI2K-LP was compared with LP conjugated high molecular weight PEI (25,000 Da, PEI25K) in terms of toxicity and delivery efficiency. MTT assay showed that PEI2K-LP had much lower cytotoxicity than PEI25K-LP to 293 cells. In addition, cell-free DNA delivery assay showed that PEI2K-LP delivered more DNA to mitochondria at a 1.8/1 weight ratio than naked DNA or PEI. This result suggests that PEI2K-LP may be useful for the development of mitochondrial gene therapy system with lower cytotoxicity.
Purification and Characterization of Helicobacter pylori ${\gamma}$-Glutamyltranspeptidase
Song, Jae-Young,Choi, Yeo-Jeong,Kim, Jeong-Min,Kim, Yoo-Ree,Jo, Jin-Seong,Park, Jin-Sik,Park, Hee-Jin,Song, Yun-Gyu,Lee, Kon-Ho,Kang, Hyung-Lyun,Baik, Seung-Chul,Youn, Hee-Shang,Cho, Myung-Je,Rhee, Kw The Korean Society for Microbiology 2011 Journal of Bacteriology and Virology Vol.41 No.4
Gamma-glutamyltranspeptidase (GGT) was purified to electrophoretic homogeneity from the cell extract of H. pylori. The purified enzyme consisted of heavy and light subunits with molecular weights of 38 kDa and 21 kDa, respectively. N-terminal amino acid sequence of heavy and light subunits revealed that H. pylori GGT was processed into 3 parts for a signal peptide of 27 amino acid residues, a heavy subunit of 352 residues, and a light subunit of 188 residues during translation. The reaction rate for hydrolysis of ${\gamma}$-GpNA was 84.4 ${\mu}mol/min$ per milligram of protein, and that for the ${\gamma}$-glutamyl transfer from ${\gamma}$-GpNA to gly-gly was 23.8 ${\mu}mol/min$ per milligram of protein. The apparent Km values of H. pylori GGT for ${\gamma}$-glutamyl compounds were on the order of $10^{-3}$ to $10^{-4}$ M and those for acceptor peptides and amino acids were on the order of $10^{-1}$ to $10^{-2}$ M. The GGT protein kept approximately 80% of the initial enzymatic activity on incubation at $60^{\circ}C$ for 15 min. The optimum temperature and pH for reactions of both hydrolysis and transpeptidation were $40^{\circ}C$ and 9.0, respectively. The transpeptidation and hydrolysis reactions catalyzed by H. pylori GGT were strongly inhibited by L-Gln and moderately inhibited by L-Ala, L-Ser, ${\beta}$-chloro-L-Ala, and L-Glu. These results demonstrated that the biochemical properties of H. pylori GGT are different from those of other bacterial GGTs. Further, H. pylori GGT might degrade glutathione in the gastric mucous layer of humans if the enzyme could be secreted in the bacterial niches.
원인 불명의 실신 환자의 진단에 있어서 Head - up tilt Test 의 유용성과 혈관미주신경성 실신 환자의 임상적 특징
윤호중(Ho Joong Youn),정욱성(Wook Sung Chung),백상홍(Sang Hong Baek),김철민(Chul Min Kim),박인수(In Soo Park),김재형(Jae Hyung Kim),최규보(Kyu Bo Choi),홍순조(Soon Jo Hong) 대한내과학회 1994 대한내과학회지 Vol.47 No.2
N/A Background: Syncope, defined as a transient loss of consciousness, is a frequently encountered symptom, but despite thorough clinical and invasive diagnostic investigation, the cause of syncope remains unexplained. In recent years, head-up tilt test has been of increasing interest as a diagnostic aids in patients with unexplained syncope. We studied to define the usefulness of various diagnostic test in the evaluation of patients with recurrent syncope, to assess the usefulness of head-up tilt test in the working of syncope of unknown origin and to evaluate the clinical characteristics of subgroups of patients with syncope induced by head-up tilt test. Methods: Between June, 1991 and November, 1992 at St. Mary`s hospital, 21 patients with history of syncope and 24 control subjects without history of syncope underwent 60° head-up tild test for 60 min. Results: 1) The definite cause for recurrent syncope were diagnosed in 10 of patients (47,6%) after clinical and invasive tests. 2) During head-up tilt test, vasovagal responses were provoked in 5 of 21 patients (23.8%) with recurrent syncope and 1 of 24 patients (4.2%) without syncope (p<0,05). 3) The head-up tilt test induced symptomatic bradycardia or hypotension in 3 of 10 patients (30%.) with negative electrophysiologic results. 4) During tilt induced vasovagal response, a) mean heart rate decreased to 42±24 beat/min from supine control of 70±12 beat/min (p<0. 05), b) mean systolic blood pressure decreased to 95±12 mmHg from supine control of 120±S mmHg (p<0,05), c) mean diastolic blood pressure decreased to 60±21mmHg from supine control of 72±13 mmHg (p<0.05), d) the time interval to onset of vasovagal response was 22±12 min. Conclusions: 1) In a large proportion of patients with recurrent syncope, the diagnosis remains unexplained despite a neurologic and cardiologic investigation including an electrophysiologic study. 2) Vasovagal responses are frequent cause in patients with recurrent unexplained syncope. 3) The head-up tilt test may be a simple, safe and highly yielding provocative test in the investigation of syncope of unknown origin.
쌍방향 Compunication Local Network 구축과 활용
최계호,김용현,이형민,김정숙,황용하 대구산업정보대학 2001 논문집 Vol.15 No.-
Since we are in the transitory era from the age of industrialization to the age of information, it is necessary to accomplish an effective localization of the information. Accordingly, the college tries to construct the bi-directional Communication Local Network so that we can provide the local design companies with technical information and that we can achieve the characterization of the college and its differentiation from the local colleges, which will help us produce the better professionals and eventually provide us the foothold that will make the college a heralding force of the national development and the localization of the information. With the CLN research center, the college can play a key role in providing the necessary information and technologies for the design-related companies in Kyeongsangbuk Province and become a corner stone for the localization of the information and the information-oriented nation.
최병태,이형민,전상봉,서승교,이우언,백종현 대구산업정보대학 2001 논문집 Vol.15 No.-
The aim of this paper is to form and to operate EQM, to say education quality management. In order to achieve the above stated purpose, the paper hypothesizes that there are similarities between enterprises and colleges in quality management. The basic method of the paper is systematic approach, modifies TQM, which is total quality management. The result is that EQM program must form and operate the feedback system for teaching and learning effect, the PSMT(project, self-study, media, team unit style teaching and learning) as a new teaching and learning method, and the digital system as an advanced mechanism, in education quality management.
다발성 간종괴의 형태로 나타난 특발성 과호산구 증후군 치험1예
최승오,연규민,이승민,김순제,왕준호,박형석,이재동,진춘조,이창훈,신현준,김정은 건국대학교 의과학연구소 2004 건국의과학학술지 Vol.14 No.-
Hypereosinophilic syndrome is characterized by persistent blood eosinophilia of 1,500/ul or more in the absence of known causes and multiorgan dysfunction by eosinophil-related tissue damage. In Korea, some cases of hypereosinophilic syndrome with hepatic involvement have been described with prolonged benign clinical courses. Most of them were diffuse or multifocal lesions in imaging studies, and a few case presenting as a single mass has been described. Here we report a case of hypereosinophilic syndrome with hepatic involvement in a 65-year-old man who presented with multifocal mass lesions. By abdominal US and CT scan, multiple, ill-defined nodules were detected in throughout the liver. Liver biopsy revealed severe eosinophilic hepatitis, suggestive of hypereosinophilic syndrome. Hepatic mass lesions improved after steroid administration for several weeks.