• Applied Science and Convergence Technology
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• v.24 no.6
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• pp.278-283
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• 2015

In this work, the electrical bistability of an organic CT complex is demonstrated and the possible switching mechanism is proposed. 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and tetracyanoquinodimethane (TCNQ) are used as an organic donor and acceptor, respectively, and poly-methamethylacrylate (PMMA) is used as a polymeric matrix for spin-coating. A device with the Al/($Al_2O_3$)/PMMA:BCP:TCNQ[1:1:0.5 wt%]/Al configuration demonstrated bistable and switching characteristics similar to Ovshinsky switching with a low threshold voltage and a high ON/OFF ratio. An analysis of the current-voltage curves of the device suggested that electrical switching took place due to the charge transfer mechanism.

• Journal of Acupuncture Research
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• v.17 no.2
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• pp.247-259
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• 2000

Objective : The mechanism of acupuncture to increase cerebral blood flow is still uncertain. The purpose of this study was to evaluate the neural basis of acupuncture by comparing the cerebral regions activated by the stimulation of two different methods of acupunctures at the same acupoint which was suggested by oriental medicine to increase rCBF. Materials and Methods : Thirty-nine healthy volunteers(26 males, 13 females, age $31{\pm}11$ years) were studies by rest/acupuncture Tc-99m ECD brain SPECT using a subtraction method. SPECTs using two methods(needle retention and heated needle with 90% alcohol) at two acupoints (right LI. 4 and ST. 36) were peformed at an interval of three days. For the needle retention method, acupuncture needle was inserted to a depth of about 2 cm into each acupoint 8 minutes after the lst acquisition and continued to retain, and the second injection of Tc-99m ECD was done 15 minutes after the insertion of needle. For the heated acupuncture method, heated needle was inserted in a twinkle within several msec 20 second after the second injection of Tc-99m ECD. The differences of between rest and acupuncture activation state were statistically analyzed using a statistical parametric mapping software. Result : Acupunctures of both methods reveal similar patterns of increase in rCBF. Acupuncture at ST.36 increase rGBF in left anterior temporal, right inferior frontal lobes, and left cerebellum. Acupuncture at LI. 4 increase rCBF in the left frontal cortex, right temporal pole, both inferior frontal cortices and right cerebellum. Conclusion : The effects of two different acupunctures to the same acupoints on rCBF were similar. Therefore, this result suggests Chat the mechanism of acupuncture in the increase of cerebral blood flow have a neural basis.

• Nuclear Engineering and Technology
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• v.44 no.3
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• pp.237-248
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• 2012

Corium behavior in the lower plenum of the reactor vessel during a severe accident is very important, as this affects a failure mechanism of the lower head vessel and a thermal load to the outer reactor vessel under the IVR-ERVC (In-Vessel corium Retention through External Reactor Vessel Cooling) condition. This paper discusses the state of the art and technical issues on corium behavior in the lower plenum, such as initial corium pool formation characteristics and its transient behavior, natural convection heat transfer in various geometries, natural convection heat transfer with a phase change of melting and solidification, and corium interaction with a lower head vessel including penetrations of the ICI (In-Core Instrumentation) nozzle are discussed. It is recommended that more detailed analysis and experiments are necessary to solve the uncertainties of corium behavior in the lower plenum of the reactor vessel.

• Journal of the Korean Chemical Society
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• v.29 no.4
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• pp.365-371
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• 1985

A cationic dye, methylene blue $(MTB^+)$ was examined as a counter ion in the separation of organic and inorganic anions by ion-pair chromatography. Nonabsorbing anions could be indirectly detected by photometric detector with the assistance of MTB^+ in visible range (665nm). A mixture of anions was able to be separated with good base line resolution and high sensitivity. The capacity factors were also determined in various experimental conditions to study retention mechanism. The retention followed the ion-interaction model where the $MTB^+$ occupies a primary layer at the stationary phase while the analyte anion and other anions in the system compete for forming the secondary layer.

• Analytical Science and Technology
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• v.11 no.4
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• pp.292-296
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• 1998

Normal phase or reversed phase liquid chromatographic separation of isoquinoline of heterocyclic compounds and structural isomers of external substituents, $COOCH_3$, CN and $CH_3$ has been carried out by using several different columns and various mobile phases. From this results, the order of elution of heterocyclic compounds appears to depend on the solvent effect with kinds of mobile phases. Retention mechanism of normal phase system for 2-methylindoline, 2-methylindole, benzoxazole and benzothiazole was also studied depending on adsorption strength between solute and stationary phase of column. However, retention factors of reversed phase system were found on hydrophobic interaction with solvophobic effect.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.3
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• pp.52-59
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• 2004

The greater Increase of the demand for environmental friendly materials especially for packaging industry leads to the larger interest in the reusable and recycable materials such as pulp mold. Although the pulp mold has great characteristics for packaging, some deficiency compared with other packaging material like EPS(Expandable Polystyrene) need to be overcome, for example, the relative higher cost. In this report, since the water drainage rate at the forming zone of a wet pulp mold process could have a great influence on the economical efficiency not only by increasing machine speed but also reducing the drying energy, the optimum ways for increasing drainage were investigated The mechanism of vacuum drainage In pulp mold forming was successfully evaluated by using RDA(Retention and Darinage Analyzer). Since the conditions of stock were greatly affected by the pulping time of low consistency pulper, the optimum pupling time was investigated with considerations of all stock preparation processes. The change of stock temperature and the addition of polyelectrolyte could improve the vacuum drainage rate. It was founded that the wire mesh types of mold former had a little influence on the retention because of the relatively mild vacuum drainage. However, the bigger size of dewatering hole showed better drainage rate and could reduce the plugging and con lamination of mold.

• Bulletin of the Korean Chemical Society
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• v.11 no.5
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• pp.411-415
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• 1990

The dabsylation of amino acids has been applied to resolve their optical isomers with the use of chiral mobile phase in high performance liquid chromatography. The dabsyl amino acids were successfully separated on reversed phase column($C_{18}$) by adding a chiral L-benzylproline-Cu(II) chelate to the mobile phase. The separation selectivity of the dabsyl amino acid enantiomers was not less than that of dansyl amino acids. The retention order of the dabsyl amino acid enantiomers was as those of the dansyl amino acid enantiomers except dabsyl threonine. The optical selectivity of the dabsyl amino acids increase with pH of the mobile phase and concentration of the chelate, but slightly decreases with concentration of buffer and organic solvent composition. However serine, methionine, valine, and leucine showed a slight decrease in the optical selectivity with increase in pH. The retention times of the dabsyl amino acids decreases with increasing pH and acetonitrile concentration but increases with the concentration of the chiral chelate added. The mechanism of the optical resolution is based on a stereospecific interaction including a intramolecular hydrophobic effect and SN-2 reactivity of the ligand exchange chromatography.It is advantageous to detect absorption at 436 nm, which is less interferent them the other detection systems. The derivatized dabsyl amino acids are stable for a month.

• Asian-Australasian Journal of Animal Sciences
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• v.1 no.2
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• pp.81-88
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• 1988

Experiments were conducted with chicks and pigs to determine whether the sparing effects of cobalt (Co) or nickel (Ni) on zinc (Zn) nutrition were due to an improved Zn availability. They included a Zn balance study with New Hampshire X Leghorn cross chicks, a $^{65}Zn$ absorption study with Ancona chicks and a $^{65}Zn$ balance study with pigs. The basal diet was a corn-soybean type diet high in calcium. In the Zn balance study with New Hampshire X Leghorn cross chicks, Zn retention percentages for basal, + 54 ppm Ni or + 54 ppm Co were 39.4, 40.4 and 48.3, respectively. In the $^{65}Zn$ absorption study with chicks, adding these levels of Ni or Co to the basal diet increased $^{65}Zn$ absorption from 12.8% to 14.0% and 15.1%, respectively. Supplemental Ni and Co increased the proportion of body $^{65}Zn$ found in liver and bone. With the pig experiment, $^{65}Zn$ retention percentages for basal, +54 ppm Co and + 60 ppm Zn groups were 20.0, 26.7 and 12.2, respectively; while Zn retention values (mg) in the body were 29.5, 45.1 and 60.5, respectively. In addition, supplemental Co increased $^{65}Zn$ concentration in the blood, liver, kidney and duodenum. These studies showed that supplementation of the basal diet with Co resulted in increased absorption of dietary Zn in chicks and pigs. The effect of Ni in chicks was less than that of Co. The ability of supplemental Co and to a lesser extent of Ni to improve weight gain as well as reduce other Zn-deficient signs in both species fed a practical corn-soybean type diet high in in calcium can be explained, at least in part by an associated increase in Zn absorption. The possible mechanism involved in these effects are discussed.

• Korean Journal of Oriental Medicine
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• v.8 no.1
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• pp.109-126
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• 2002

The herbal extract (YMT_02) is a modified herbal extracts from Yukmijihwangtang (YMJ) to promote memory-enhancing. The YMJ extracts has been widely used as an anti-aging herbal medicine for hundred years in Asian countries. The purpose of this study is to; 1) quantitatively evaluate the memory-enhancing effect of YMT_02 by hehavior task, 2) identify candidate genes responsible for enhancing memory by cDNA microarray and 3) assess the anti-oxidant effect of YMT_02 on PC12 cell. Memory retention abilities are addressed by passive avoidance task with Sprague-Dawley (SD) male rat. Before the training session, the rats are subdivided into four groups and administrated with YMT_02, Ginkgo biloba, Soya lecithin and normal saline for 10 days. The retention test was performed. 24 hours after the training session. The retention time of the YMT_02 group was significantly (p<0.05) delayed $({\sim}100%)$, whereas Ginkgo biloba and Soya lecithin treatment delayed 20% and 10% respectively. The hippocampi of YMT_02 and control group were dissected and mRNA was further purified. After synthesizing cDNA using oligo-dT primer, the cDNA were applied and mRNA was further purified. After synthesizing cDNA using oligo-dT primer, the cDNA were applied to Incyte rat GEMTM 2 cDNA microarray. The microarray results show that prealbumin(transthyretin), phosphotidy lethanolamine N-methyltransferase, and PEP-19 are expressed abundantly in the YMT_02 treated group. Especially, PEP-19 is a neuron-specific protein, which inhibits apoptotic processes in neuronal cell. On the other hand, transcripts of RAB15, glutamate receptor subunit 2 and CDK 108 are abundant in control group. Besides, neuronal genes involved in neuronal death or neurodegeneration such as neuronal-pentraxin and spectrin are abundantly expressed in control group. Additionally, the YMT_02 shows an anti oxidative effect in the PC12 cell. The list of differentially expressed genes may implicate further insight on the action and mechanism behind the memory-enhancing effect of herbal extracts YMT_02, for example, anti-apoptotic, anti-oxidative, and neuroprotective effects.

• Analytical Science and Technology
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• v.7 no.3
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• pp.379-386
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• 1994

The elution behaviors in reversed-phase liquid chromatography were investigated thermodynamically for 2-hydroxy-arylazopyrazolone chelates with Ni(II), Cu(II), Co(III), Cr(III) on Novapak $C_{18}$ column. There was a good linear dependence of the capacity factor(k') on the variations of column temperature in van't Hoff plot. From this result, it was confirmed that the retention mechanism of these chelates in the reversed phase liquid chromatography system was invariant under the condition of various temperatures. For the most cases of the chelates studied, the dependence of capacity factor(1n k') on enthalpy$(-{\Delta}H)^{\circ}$, calculated by van't Hoff plot showed a good linearity(r=0.980~0.999) except [Pm(2-OH_(5-Cl)PaPz](r=0.787) and also the compensation temperatures(${\beta}$) showed constant values. The range of compensation temperature values calculated from the slope of $-{\Delta}H^{\circ}$ vs 1n k' plots was 374.3~806.9K. It was suggested that the retention of metal-2-hydroxy-arylazopyrazolone chelates in the reversed phase liquid chromatography system was largely affected by the hydrophobic effect.