• Restorative Dentistry and Endodontics
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• v.29 no.2
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• pp.153-161
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• 2004

This study investigated that the effect of rewetting agent on dentinal microtensile bond strength(${\mu}TBS$). Human molars were sectioned to expose the superficial dentin surfaces. Samples were divided into two groups according to type of adhesives-Single Bond (S) and One-Step (0)], and again subdivided into five groups by different dentin surface treatment-dry for 15s (D), blot dry (BD) or dry for 15s, and rewet with different rewetting agents [distilled water (DW), Gluma Desensitizer (GD) and Aqua-Prep (AP)] for 30s. After application of adhesive, composite resin was built up on the bonding surface. Each tooth was sectioned to obtain stick with $1\textrm{mm}^2$ cross sectional area and the ${\mu}TBS$ was determined by EZ test. In the S group, the mean ${\mu}TBS$ of GD, AP, and BD group was significantly higher than that of DW and D group (p < 0.05), In the O group, the mean, ${\mu}TBS$ of AP, GD, BD and DW group was significantly higher than that of D group (p < 0.05). The data suggested that Gluma Desensitizer and Aqua-Prep could be successfully used as rewetting agents, and Distilled water could be acceptable in aceton based adhesive system only.

• Korean Journal of Food Science and Technology
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• v.23 no.3
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• pp.251-255
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• 1991

The antioxidative effects of the six commercial lecithins, tocopherols, citric acid and ascorbyl palmitate on refined perilla oil were inverstigated by active oxygen method ($AOM,\;hrs\;at\;97.8^{\circ}C$) and oven test. Except for the lecithin I (aceton insoluble content 55%), the induction time on perilla oil treated with commercial lecithins at 5% level was longer than that of refined soybean oil. When the concentration of lecithin (0.5, 1, 2.5, 4 and 5%) in perilla oil was increased, enhanced the antioxidative effect at AOM and oven test. Lecithin also showed synergistic effect with the mixtures of tocopherol, citric acid and ascorbyl palmitate. The antioxidative effect of ${\gamma}-rich-tocopherol$ on perilla was higher than that of ${\dalta}-rich-tocopherol$ or mixed tocopherol.

• Korean Journal of Food Science and Technology
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• v.32 no.6
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• pp.1234-1243
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• 2000

A method for quantitative determination of styrene dimer and trimer, which are suspected as endocrine disruptors, in foods and containers was studied. For residual contents of styrene dimer and trimer in two-kinds of containers, which contained instant noodle and yogurt, sample pieces were completely dissolved in tetrahydrofuran. The polymer was precipitated with n-hexane, a portion of supernatant was concentrated for analysis. A sensitive method was also optimized for the quantification of styrene dimer and trimer in foods such as instant cup noodle and yogurt by using GC/MS. Limits of Detection were about 3.2-87.0 ppb for styrene dimers and trimers. The highest recovery was obtained by extraction with acetone/hexane(1:1), followed by florisil clean-up. The levels of styrene dimer and trimer migrated by food simulants were much higher in heptane.

• Journal of Applied Biological Chemistry
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• v.53 no.1
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• pp.21-24
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• 2010

In recent years, many agricultural scientists are studying on eco-friendly farming methods. Among of lots of the methods, the natural insecticides are highly motivated and interested due to their safety and biodegradable issues, and readily available source of bioinsecticides. In this study, the crude extract of custard apple (Annona reticulata L.) seed and its three fractions which were separated based on polarity indexes were examined for their insecticidal activities against Myzus persicae Sulzer and Nilaparvata lugens S.. The crude extract (Aceton/MeOH) showed strong insecticidal activities against both insects at 3.00 mg/mL ($LD_{50}$=0.45mg/mL for M. persicae S. and 1.42 mg/mL for N. lugens S.). Furthermore, simple fractionation with hexane, chloroform, and water lead to increase three-folds insecticidal activity on chloroform fraction ($LD_{50}$=0.13mg/mL for M. persicae S. and 1.14 mg/mL for N. lugens S.). The results suggest that A. reticulata extracts might be used to control for M. persicae effectively.

• Journal of the Korean Chemical Society
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• v.4 no.1
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• pp.15-17
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• 1957

1. Preparation of Titanium tetrachloride; The following precesses were strictly followed as the preliminary step to obtain pure $TiOCl_2$, titanyl chloride; First, pure Titanium Oxide mixed with carbon is rolled into pills. After drying up perfectly, these pills are heated at 900∼1000${\circ}C$. And then the pills are subjected to the flow of $Cl_2$ gas in a quartz tube heated to 900-1000${\circ}C$. Thus Titanium tetrachloride is obtained. 2. Preparation of $TiOCl_2$ ; Yellowish trobrown solution is made by pouring 80 g of conc. HCl (sp.gr. 1.19) to 45 gr of Titanium tetrachloride (approx. 2 times of theoretical amount). Then this solution is kept settled for 5-days in a desiccator filled with phosphorous pentoxide at room temperature. As the colorless amorphous solid thus obtained is washed with aceton, 36.5 g of the pure salt are obtained. 3. Determination of composition. The analysis of the sample taken from the deposit desiccated gives the following data; (A) Qualitative analysis; a) $Ti(OH)_4$ is precipitated by adding NaOH in water solution of the salt. b) Adding $AgNO_3$ solution, the water solution of the salt gives white precipitate of AgCl. c) When acid and $H_2O_2$ are added, the solution turns its color to redish brown (This proves that $TiO^{++}$ was converted into $TiO^{++}$ by oxidation of $H_2O_2$. (B) Quantitative analysis; a) $Ti(OH)_4$ precipitated by $10{\%}$ NaOH isalitatsubjected consecutively to the filtration and ignition in porcelain crucible at approx. 1000${\circ}C$. , then $TiO_2$ thus formed is weighed and calculated into Ti content. b) Chlorine involved in water solution of the salt is determined by Vorhardt method. Result: The values obtained from previous analysis, devied by their atomic weight gives the following composition: Ti : Cl = 1 : 2 Therefore $TiOCl_2$ should be given as its molecular formula. 4. Summary. When $TiCl_4$ is additated into conc. HCl, $TiO^{++}$ formed exists as a stable form, and forms $TiOCl_2$. However $TiOCl_2$ is unstable to heating. When the temperature is raised to $65{\circ}C$the decomposition of the solution is accelerated, and gives $TiO_2$ aq. $TiOCl_2$ in addition is highly hygroscopic.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.2
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• pp.28-34
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• 2011

In previous reports, we investigated a selective assembly method of fabricating single-walled carbon nanotubes (SWCNTs) on a silicon-dioxide ($SiO_2$) surface by using only a photolithographic process. In this paper, we have fabricated field effect transistors (FETs) with SWCNT channels by using the technique mentioned above. Also, we have electrically measured gating effects of these FETs under different source-drain voltages ($V_{SD}$). These FETs have been fabricated for sensor applications. Photoresist (PR) patterns have been made on a $SiO_2$-grown silicon (Si) substrate by using a photolithographic process. This PR-patterned substrate have been dipped into a SWCNT solution dispersed in dichlorobenzene (DCB). These PR patterns have been removed by using aceton. As a result, a selectively-assembled SWCNT channels in FET arrays have been obtained between source and drain electrodes. Finally, we have successfully fabricated 4 FET arrays based on SWCNT-channels by using our simple self-assembly technique.

• Korean Journal of Weed Science
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• v.8 no.3
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• pp.283-290
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• 1988

This study was conducted to clarify the identification of phytotoxic compounds from 5 upland weeds which had been collected at their maturity age in the field of Kyungpook province, Korea. 5 weed species including Stellaria aquatica strongly inhibited the lettuce seed germination. These 5 species were Amaranthus lividus, Stellaria aquatica, Achyranthes japonica, Polygonum perfoliata and Galinsoga ciliata. the degree of inhibitory effects according to various solvent extracts such as ethanol, aceton, chloroform and ether was different as species. In total phenol and diphenol content G. ciliata had largest amount of total phenol with 2.75mg/g, P. perfoliata 1.8mg/g, S. aquatica 1.7mg/g, A. lividus 1.28mg/g, A. japonica 1.27mg/g respectively. A. lividus had much amount of p-cresol, hydroquinone, ferulic, caffeic, p-cl-benzoic and p-coumaric in order. S. aquatica, A. japonica, P. perfoliata and G. ciliata had a large quantity of ferulic, caffeic, 7-OH-coumarin and protocatechuic acids in common. The amount of fatty acids was existed 8.49mg/g in S. aquatica, 7.14mg/g in A. japonica, 7.10mg/g in G. ciliata, 5.49mg/g in P. perfoliata and 4.2mg/g in A. lividus respectively. Most of 4 weeds except G. ciliata had much oxalic acid to the extent of 14-22mg/g. however it appeared that G. ciliata had much quantity of feruic and citric acids.

• Korean Journal of Weed Science
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• v.9 no.2
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• pp.154-167
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• 1989

This study was conducted to determine the influence of various extracts from 21 medicinal plants including Bupleurm falcatum on the germination and growth of Lactuca sativa, Oryza native and E. crus-galli var. crus-galli, and the amount of their phenolic acids, fatty acids and organic acids, Water extract(5%) of all the medicinal plants, particularly Acorus gramineus, Cnidium officinale, Aconitum carmicheali, Bulpeurum falcatum, Zingiber officinale, Angelica gigas and Curcuma zeodaria inhibited over 90% of the lettuce seed germination and growth, indicating that medicinal plants contained the biologically active substances. The highest amount of phenolic compounds was observed in Prunus crmenica var, ansu(30.6013mg/g) followed by Aconitum ciliare(29.1008mg/g) and Cnidium officienale(27.2943mg/g) which inhibited markedly the germination of testing plants, showing the close relation of phenolic compounds to inhibitory effects. Cnidium officinale contained the highest amount of fatty acids(24.10mg/g) and organic acids(21.04mg/g) which may be partly related to inhibitory effects.

• Journal of the Korean Chemical Society
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• v.29 no.6
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• pp.629-636
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• 1985

The rates of solvolysis of trans-$[Co(AA)_2Cl_2]^+$ in which AA indicates ethylenediamine(en), N-ethylethylenediamine (N-eten), N-methylethylenediamino (N-meen) and trimethylenediamine(tn) respectively have been investigated using conductometric and spectrophotometric methods at various pressure up to 2,000 bar in acetone-water mixture. The activation volumes (${\Delta}V^{\neq}) obtained from the pressure effect on rate constants were -0.2∼0.9 $cm^3mole^{-1}$ for en, -0.2∼0.6 $cm^3mole^{-1}$ for N-eten, -0.8∼6.0 $cm^3mole^{-1}$ for N-meen and 0.7∼7.0$cm^3mole^{-1}$ for tn. The rates of solvolysis of these complexes were analyzed by comparing with the results obtained from excess free energy ($G^E$) and free energy cycle. It was found that $S_N1$ character was increased with decreasing the pressure and increasing the content of acetone in the mixture solvent. In addition to that, the effect of charge separation on the mechanism of solvolysis was discussed.

• The Korean Journal of Zoology
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• v.21 no.1
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• pp.29-39
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• 1978

The authors observed the ultrastructure of the mucous glandular epithelial cells in the amphibian skin by mean of electron microscope. The specimens from the experimental animals were fixed in 2.5% glutaraldehyde-oaraformaldehyde fixative in phosphate buffer at pH 7.2 prior to fixation in 1% osmium tetroxide, dehydrated in graded ethanol and acetone, embedded in Epon 812 mixture, and sectioned with Sorvall MT-2 ultramicrotome. The ultrasections were contrasted with uranyl acetate and lead citrate and observed with a JEOL-100B electron microscope. The results were as follows: 1. The cutaneous mucous glands in amphibia consisted of the glandular epithelial and the myoepithelial cells. 2. Several different cells in ultrastructure were observed in the mucous glandular epithelium of the adult amphibian skin. a. The dark and the light cells were observed in Hynobius leechi. b. The mitochondria-rich and the round secretory granule-containing cells were observed in Bombina orientalis. c. The round secretory granule-containing and the foam-like granule mass-containing cells were observed in Kaloula tornieri. d. The cutaneous mucous gland of Rana nigromaculata were divided into two types: A and B-type glands. In the A-type mucous gland, the mitochondria-rich and the round secretory granule-containing cells and in the B-type mucous gland, the mitochondria-rich, the secretory granule-containing and the ER-rich cells were observed. 3. Based upon the above findings, the authors infer that the mucous granular epithelium of the amphibian skin consists of the mitochondria-rich undifferentiated, the secetory granule-containing and mature, and the ER-rich evacuated cells.