• Carbon letters
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• v.11 no.4
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• pp.279-284
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• 2010

Graphene is one of the most promising materials for many applications. It can be used in a variety of applications not only as a reinforcement material for polymer to obtain a combination of desirable mechanical, electrical, thermal, and barrier properties in the resulting nanocomposite but also as a component in energy storage, fuel cells, solar cells, sensors, and batteries. Recent research at Michigan State University has shown that it is possible to exfoliate natural graphite into graphite nanoplatelets composed entirely of stacks of graphene. The size of the platelets can be controlled from less than 10 nm in thickness and diameters of any size from sub-micron to 15 microns or greater. In this study we have investigated the influence of melt compounding processing on the physical properties of a polyamide 6 (PA6) nanocomposite reinforced with exfoliated graphite nanoplatelets (xGnP). The morphology, electrical conductivity, and mechanical properties of xGnP-PA6 nanocomposite were characterized with electrical microscopy, X-ray diffraction, AC impedance, and mechanical properties. It was found that counter rotation (CNR) twins crew processed xGnP/PA6 nanocomposite had similar mechanical properties with co-rotation (CoR) twin screw processed or with CoR conducted with a screw design modified for nanoparticles (MCoR). Microscopy showed that the CNR processed nanocomposite had better xGnP dispersion than the (CoR) twin screw processed and modified screw (MCoR) processed ones. It was also found that the CNR processed nanocomposite at a given xGnP content showed the lowest graphite X-ray diffraction peak at $26.5^{\circ}$ indicating better xGnP dispersion in the nanocomposite. In addition, it was also found that the electrical conductivity of the CNR processed 12 wt.% xGnP-PA6 nanocomposite is more than ten times higher than the CoR and MCoR processed ones. These results indicate that better dispersion of an xGnP-PA6 nanocomposite is attainable in CNR twins crew processing than conventional CoR processing.

• Journal of the Korean Magnetics Society
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• v.20 no.1
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• pp.13-17
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• 2010

Fe-3, 4.2 and 6.8% Si compressed cores were fabricated, and then electrical resistivity, AC and DC magnetic properties, microhardness, and other properties were analyzed in order to know whether best soft magnetic properties could be also obtained in an Fe-Si compressed core with the well-known composition of Fe-6.5% Si. With increasing the silicon content, eddy current loss and hysteresis loss decreased and increased, respectively, so that a minimum total loss was not obtained in the well-known Fe-6.8 % Si cores, but obtained in the Fe-4.2 % Si cores. Also electrical resistivity of the cores and hardness of the particles increased monotonously with silicon content so that compaction ratio of the cores decreased. B2 and $DO_3$ ordered phase could be observed only in Fe-6.8% Si powder. A minimum loss and highest permeability of the Fe-4.2 % Si cores can be explained by the ratio of specific electrical resistivity of insulator to that of magnetic particles, micro-hardness, compaction ratio and demagnetization coefficient of the Fe-Si powder particles with silicon content.

• Archives of Pharmacal Research
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• v.24 no.2
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• pp.126-135
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• 2001

Quinacrine (QU), a phospholipase-A2 (PLA-2) inhibitor has been used clinically as a chemotherapeutic adjuvant. To understand the mechanisms leading to its chemotherapeutic effect, we have investigated QU-induced apoptotic signaling pathways in human cervical squamous carcinoma HeLa cells. In this study, we found that QU induced cytochrome c-dependent apoptotic signaling. The release of pro-apoptotic cytochrome c was QU concentration- and time-dependent, and preceded activation of caspase-9 and -3. Flow cytometric FACScan analysis using fluorescence intensities of $DiOC_6$/ demonstrated that QU-induced cytochrome c release was independent of mitochondrial permeability transition (MPT), since the concentrations of QU that induced cytochrome c release did not alter mitochondrial membrane potential (${\blacktriangle}{\Psi}_m$). Moreover, kinetic analysis of caspase activities showed that cytochrome c release led to the activation of caspase-9 and downstream death effector caspase-3, Caspase-3 inhibitor (Ac-DEVD-CHO) partially blocked QU-induced apoptosis, suggesting the importance of caspase-3 in this apoptotic signaling mechanism. Supplementation with arachidonic acid (AA) sustained caspase-3 activation induced by QU. Using inhibitors against cellular arachidonate metabolism of lipooxygenase (Nordihydroxyguaiaretic Acid, NDGA) and cyclooxygenase (5,8,11,14-Eicosatetraynoic Acid, ETYA) demonstrated that QU-induced apoptotic signaling may be dependent on its role as a PLA-2 inhibitor. Interestingly, NDCA attenuated QU-induced cytochrome c release, caspase activity as well as apoptotic cell death. The blockade of cytochrome c release by NDCA was much more effective than that attained with cyclosporin A (CsA), a MPT inhibitor. ETYA was not effective in blocking cytochrome c release, except under very high concentrations. Caspase inhibitor z-VAD blocked the release of cytochrome c suggesting that this signaling event is caspase dependent, and caspase-8 activation may be upstream of the mitochondrial events. In summary, we report that QU induced cytochrome c-dependent apoptotic signaling cascade, which may be dependent on its role as a PLA-2 inhibitor. This apoptotic mechanism induced by QU may contribute to its known chemotherapeutic effects.

• Journal of Ginseng Research
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• v.38 no.4
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• pp.278-288
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• 2014

Background: Panax ginseng Meyer is a traditional medicinal plant famous for its strong therapeutic effects and serves as an important herbal medicine. To understand and manipulate genes involved in secondary metabolic pathways including ginsenosides, transcriptome profiling of P. ginseng is essential. Methods: RNA-seq analysis of adventitious roots of two P. ginseng cultivars, Chunpoong (CP) and Cheongsun (CS), was performed using the Illumina HiSeq platform. After transcripts were assembled, expression profiling was performed. Results: Assemblies were generated from ~85 million and ~77 million high-quality reads from CP and CS cultivars, respectively. A total of 35,527 and 27,716 transcripts were obtained from the CP and CS assemblies, respectively. Annotation of the transcriptomes showed that approximately 90% of the transcripts had significant matches in public databases.We identified several candidate genes involved in ginsenoside biosynthesis. In addition, a large number of transcripts (17%) with different gene ontology designations were uniquely detected in adventitious roots compared to normal ginseng roots. Conclusion: This study will provide a comprehensive insight into the transcriptome of ginseng adventitious roots, and a way for successful transcriptome analysis and profiling of resource plants with less genomic information. The transcriptome profiling data generated in this study are available in our newly created adventitious root transcriptome database (http://im-crop.snu.ac.kr/transdb/index.php) for public use.

• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1075-1082
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• 1999

Composite air electrodes of 50/50 vol% LSM- YSZ where LSM =$\textrm{La}_{1-x}\textrm{Sr}_{x}\textrm{MnO}_{3}$(0$\leq$x$\leq$0.5) were prepared by colloidal deposition technique. The electrodes were then examined by scanning electron microscopy (SEM) and studied by ac impedance spectroscopy in order to improve the performance of a solid oxide fuel cell (SOFC). Reproducible impedance spectra were confirmed by using the improved cell, consisting of LSM- YSZ/YSZ/LSM-YSZ. These spectra were a strong function of operating temperature and the stable conditions for the cells were typically reached at $900^{\circ}C$. The typical spectra measured for an air//air cell at $900^{\circ}C$ were composed of two arcs. Addition of YSZ to the LSM electrode led to a pronounced decrease in cathodic resistivity of LSM-YSZ composite electrodes. Polishing the electrolyte surface to eliminate the influences of surface impurities could further reduce cathode resistivity. The cathodic resistivity of the LSM-YSZ electrodes with catalytic interlayer (Ni or Sr) was much smaller than that of LSM-YSZ electrodes without catalytic interlayer. In addition, the cathodic resistivity of the LSM-YSZ electrodes was a strong function of composition of electrode materials, the electrolyte geometry, and applied current.

• Journal of Sasang Constitutional Medicine
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• v.21 no.1
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• pp.99-126
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• 2009

1. Objective TS-QSCD (The Two-Step Questionnaire for the Sasang Constitution Diagnosis) is one of the self-reporting Sasang-Constitutional diagnosis questionnaires and one constituted by a two-step discriminant function. The process of TS-QSCD is as follows. During the first step, the testers are classified into two groups: the Yangin(陽人) group and Eumin(陰人) group. Following this, the Yangin group is divided into the Soyangin group and Taeyangin group likewise the Eumin group is divided into the Taeumin group and Soeumin group. This questionnaire has the merits of an ordinary questionnaire with four discriminant functions and a decision tree method. The purpose of this study is to evaluate and standardize TS-QSCD 2. Materials and Methods TS-QSCD was administered to 352 random informants who were examined by professionals. Reliability was tested by inter-item consistency using cronbach's ${\alpha}$, and validity was tested by a two step discriminant function. Cross tabulation Analysis was also used to look into the distribution of responses among the groups. 3. Result 1) The reliability of TS-QSCD was relatively valid. The internal consistency of TS-QSCD (AB) was cronbach's ${\alpha}$= 0.815, and TS-QSCD (AC) was cronbach's ${\alpha}$= 0.832. 2) There was a significant difference in points between Eumin group teens and other age groups, between those of Soeumin teens and other age groups. 3) TS-QSCD corresponded with the real Sasang constitution at the rate of 65.0%. When using 61 questions and four discriminant function as with ordinary methods, TS-QSCD corresponded with the real Sasang constitution at the rate of 74.9%. 4. Conclusion 1) TS-QSCD that complements the merits of existing questionnaires is effective in diagnosing Sasang constitutions. 2) Deleting duplicate questions is thought to be one of the reasons for the decreased validity rate. 3) The lower the validity of the first step, the more we should build up at each second steps a way to rescue the groups which were assigned wrongly during the first steps. 4) This standardization of TS-QSCD would be helpful in making a program for diagnosing the Sasang Constitution

• Journal of Life Science
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• v.14 no.4
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• pp.620-626
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• 2004

Viruses causing acute conjuntivitis were isolated from 675 patients carrying eye infections for year 2001 to 2003 in Busan reagion and their antigenic properties characterized by a serological survey. In 2001, adenoviruses (serotype 8) were found in 5 of 48 cases. In 2002, the isolated viruses were 7 adenoviruses (serotype 8 and 37), 8 coxsakieviruses (serotype A24 and B3) and 1 echoviruses (serotype 6) from 324 specimens that are known as the causative agents of acute hemorrhagic conjuctivitis (AHC). In 2003, 25 case of 303 specimens were 7 adenoviruses (serotype 3, 4, 8 and 37), 7 echoviruses (serotype 6 and 7) and 4 untypable enteroviruses. Although coxsakievirus (serotype B3) and echoviruses (serotype 6 and 7) were generally known as causative agent of aseptic meningitis, it hasn't been reported until now that they were isolated from the conjunctival swabs. The out break of AC was observed from April to October in Busan. These isolated viruses showed a strong cytophatic effects on HEp-2, RD, Vero and BGM cell strains. Analysis of electron micrograph of those viruses showed that adenovirus consists of a 80 nm diameter and nonenvloped icosahedron and then echovirus and coxsackievirus were small nonenveloped and isometric-shaped viruses. Adenovirus showing a cytophatic effect was resulted in a 458 bp single band by PCR and echovirus, coxsackievirus and untypable enterovirus were detected a 437 bp products by RT-PCR.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.30-35
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• 1999

A simple, rapid, efficient method is for extraction of 13 synthetic water-soluble food colours (Tartrazine, Amarnth, Indigo carmine, New coccine, Sunset yellow FCF, Allura red AC, Eosine, Fast Green FCF, Brilliant Blue FCF, Erythrosine, Acid red, phloxine, Rose Bengal) by polyamide resin and for their quantitative by high performance liquid chromatography (HPLC). Colours (coal-tar dyes) were extracted with polyamide resin and then determinated by HPLC. The HPLC conditions using a reverse phase partition type column $(Nova-pak\;C_{18})$, photodiode array (PDA) detector and 1% Ammonium acetate / 60% acetonitrile in water as eluent, were acceptable for various kinds of colorants. By the use of the proposed method, a survey of coal-tar dyes was carried out on 20 samples and that were detected $4.76{\sim}133.47\;ppm$.

• Korean Journal of Medicinal Crop Science
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• v.10 no.1
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• pp.17-23
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• 2002

The seeds of Coix lachryma-jobi Linne var. mayuen Stapf. are used as dietary food for obesity and diabetes under the names of Yulmu in Korea and Yiyiren(薏苡仁) in China. It is one of the drugs promoting diuresis to eliminate the wetness-evil from the lower warmer in the traditional Korean medicine. According to ancient textbook of the traditional Korean medicine, it should be applied to patients with phlegm and heat, etc. The establishment of the method for the discrimination of Coisis Semen is very important for the quality control of drugs. Random amplified polymorphic DNA(RAPD) analysis and anatomical characteristics were used for the discrimination of Coix lachryma-jobi $Linn\acute{e}$ var. mayuen $S_{TAPF}$. and C. lachryma-jobi $Linn\acute{e}$. In the RAPD analysis with 20 primers, 8 primers gave informative and reproducible bands with the genomic DNA. From the cluster analysis, the genus Coix were divided into two groups at similarity coefficient of 0.863.

• The Korean Journal of Quaternary Research
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• v.11 no.1
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• pp.57-68
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• 1997

Climatic change of the late-Quaternary period has been record-ed in the loess deposits of the central Great plains and the record of such change is extractable using a number of approaches and parameters. The stratigraphy of loess deposits which have been investigated on Fort Riley exhibits the same sequence of loess units and intercalated buried soils as is found elsewhere in the re-gion but adds detail unique to the reservation Upland late-Qua-ternary composite stratigraphy preserved on the reservation con-sists of the basal Sangamon soil of the Last interglacial(c. 120-110ka), Gilman Canyon Formation(c. >40 -20ka), Peoria loess(c. 20 -10ka) Brady soil(c. 11 -10ka) Bignell loess(c. 9-\ulcornerka). and mod-ern surface soil. Application of magnetic analyses has provided proxy data sets that represent a time series of climatically regulated pedogenesis/weathering and botanical composition. magetic data have yielded an impression of the variation in climate from Sangamon time to the late Holocene through a reconstruction of the history of pedogenesis/weathering. Sangamon soil formation dominated the reservation durin the Last interglacial as indicated by magnetic parameters. During Gil-man Canyon time loess influx was usually sufficiently slow as to permit pedogenesis which appears to have been at a maximum twice during that time. Warm season grasses were important dur-ing soil formation but diminished in importance during the peri-ods of more rapid loess fall which were cooler and perhaps wet-ter. Peoria loess fall a function of the deterioration of climate during the last Glacial Maximum thinly blanketed the reservation with thickest accumulations occurring to the north-west(Bala Cemetery site)proximal to the source region. Long-term surface stability did not apparently occur within Peoria time but short-term stability may be indicaed by the presence of thin weathering zones(incipient soils) in the Peoria loess. Re-gional landscape stability prevailed during the environmental shift at the Pleistocene/Holocene transition resulting in forma-tion of the well expressed Brady soil. One or more weak soils developed in the Bignell loess as it ac-cumulated. A notable feature of the Bignell loess is the appear-ance of the Altithermal dry period: the loess experienced little weathering and was dominated by warm season grasses until the latter of the Holocene.