• Title/Summary/Keyword: 18-crown-6

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A RADIOLOGIC STUDY OF DENTIGEROUS CYSTS (함치성 낭종에 대한 방사선학적 연구)

  • Kang Tai Wook;You Dong Soo
    • Journal of Korean Academy of Oral and Maxillofacial Radiology
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    • v.12 no.1
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    • pp.21-26
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    • 1982
  • A radiologic study of 139 dentigerous cysts (128 patients) indicated the followings: 1. There was higher incidence in males (62.99%) than in females (37.01%). The most common age group was 11-20 years and the average age was 23.6 years. 2. The most common clinical symptoms was swelling of the jaws (49 cases, 33.09%), and no symptoms was presented in 26 cases (18.71%). 3. Dentigerous cysts were found to be slightly more common in the maxilla (53.24%) than in the mandible (46.76%) and there was almost no difference in occurance between right and left side. The maxillary supernumerary tooth was the most frequent site of the dentigerous cyst and no dentigerous cyst was found to be related to a deciduous tooth. 4. The most common radiographic findings was root resorption of the adjacent teeth (33.09%), and the central dentigerous cysts were 78 cases (56.12%), the lateral dentigerous cysts were 61 cases (43.88%). 5. The increased radiolucency at the crown portion of the tooth in a cystic cavity was seen in 44 cases (31.65%), and a case of dentigerous cyst was found in a edentulous patient, and 16 cases of multiple dentigerous cysts were found in 5 patients. 6. The ameloblastic changes in 8 cases, the keratinization of the cyst wall in 2 cases, and a case of epidermoid carcinoma were confirmed microscopically.

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The Catalytic Effect of Alkali Metal Ions on Reactions of 8-(5-Nitroquinolyl) 2-Furoate with Alkali Metal Ethoxides in Anhydrous Ethanol

  • Eum, Ik Hwan;Lee, Seong Eun;Min, Ji Suk
    • Bulletin of the Korean Chemical Society
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    • v.22 no.7
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    • pp.669-672
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    • 2001
  • Pseudo-first-order rate constants have been measured spectrophotometrically for the title reactions. The plot of kobs vs the concentration of alkali metal ethoxides is linear for the reactions performed in the presence of complexing age nt, 18-crown-6 ether, but curved upwardly for the corresponding reactions performed in the absence of the complexing agent, indicating that the alkali metal ions studied in this study behave as a catalyst. The catalytic effect was found to increase in the order Li+ << K+ ${\leq}$ Na+. Second-order rate constants were determined for the reactions with dissociated free ethoxide (kEtO-) and with ion paired alkali metal ethoxides (kEtO-M+ ) from ion pairing treatments. The magnitude of catalytic effect (kEtO-M+/kEtO-) was found to be 2.3, 9.5 and 8.7 for the reaction of 8-(5-nitroquinolyl) 2-furoate, while 1.4, 3.6 and 4.2 for that of 4-nitrophenyl 2-furoate, indicating that the catalytic effect is larger in the reaction of the former substrate than in that of the latter one. The larger catalytic effect was attributed to two possible complexing sites with alkali metal ions in the former substrate.

The Effect of Alkali Metal Ions on Reactions of 8-(5-Nitroquinolyl) 3-Furoate with Alkali Metal Ethoxides in Anhydrous Ethanol

  • Eum, Ik Hwan;Lee, Seong Eun;Min, Ji Suk
    • Bulletin of the Korean Chemical Society
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    • v.22 no.7
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    • pp.673-677
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    • 2001
  • Pseudo-first-order rate constants have been measured spectrophotometrically for the reactions of 8-(5-nitroquinolyl) 3-furoate with alkali metal ethoxides in anhydrous ethanol. The plot of kobs vs the concentration of alkali metal ethox ides is linear for the reactions performed in the presence of a complexing agent, 18-crown-6 ether, but exhibits upward curvatures for the corresponding reactions performed in the absence of the complexing agent, indicating that the alkali metal ions in this study behave as catalysts. Second-order rate constants were determined for the reactions with dissociated free ethoxide (kEtO-) and with ion paired alkali metal ethoxides (kEtO-M + ) from ion pairing treatments. The magnitude of catalytic effect (kEtO-M + /kEtO-) was found to be 1.7, 3.4 and 2.5 for the reaction of 8-(5-nitroquinolyl) 3-furoate, while 1.4, 3.6 and 4.2 for that of 4-nitrophenyl 2-furoate, 1.8, 3.7 and 2.4 for that of 8-(5-nitroquinolyl) benzoate, and 2.0, 9.8 and 9.3 for that of 8-(5-nitroquinolyl) 2-furoate with EtO- Li+ , EtO- Na+ and EtO- K+ , respectively. A 5-membered chelation at the leaving group is suggested to be responsible for the catalytic effect shown by alkali metal ions.

Effect of Cutting Time on Growth and Flowering of Double Flowered Hydrangea serrata for. acuminata (겹꽃산수국의 삽목시기가 개화에 미치는 영향)

  • Lee, Jong Suk;Kim, Hyun Jin
    • FLOWER RESEARCH JOURNAL
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    • v.18 no.1
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    • pp.33-37
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    • 2010
  • Effects of cutting time of double flowered Hydragea serrata for. acuminata native to Korea on flowering and growth of following year were investigated in order to develop as a pot plant. Cuttings were carried out every 10th day from April to September in 2008. The cuttings were directly placed in 15 cm diameter pots. Longest plant was obtained from May cuttings and their average heights were 31.7 cm, and followed by April and July cuttings. Plant heights of August and September cuttings were 23.6 cm and 22.0 cm, respectively. In contrast, growth and height of June cutting were abnormally small. Leaf length, leaf width and petiole length of August and September cutting were reduced, but numbers of leaves were not changed. Average flower cluster numbers of May cuttings were 4 flower clusters, and July, August and September cuttings were 3 clusters while only 1 flower cluster per a plant was obtained during June. Biggest diameter of flower crown was observed from May cuttings and the size was 10.3 cm diameter; however, smaller flower crown size was observed after July cuttings. The best overall flower appearance was observed from May cuttings, and the worst was June cuttings. Even though plant height of August and September cuttings were reduced, flowering aspect and ornamental value were normal, but blooming times were retarded according to late cutting time.

A Mechanistic Study on Reactions of Aryl Benzoates with Ethoxide, Aryloxides and Acetophenone oximates in Absolute Ethanol

  • 엄익환;오수진;권동숙
    • Bulletin of the Korean Chemical Society
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    • v.17 no.9
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    • pp.802-807
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    • 1996
  • Second-order rate constants have been measured spectrophotometrically for the reactions of aryl benzoates (X-C6H4CO2C6H4-Y) with EtO-, Z-C6H4O- and Z-C6H4C(Me)=NO- in absolute ethanol at 25.0 ℃. All the reactions have been performed in the presence of excess 18-crown-6 ether in order to eliminate the catalytic effect shown by alkali metal ion. A good Hammett correlation has been obtained with a large ρ- value (-1.96) when σ- (Z) constant was used for the reaction of p-nitrophenyl benzoate (PNPB) with Z-C6H4O-. Surprisingly, the one for the reaction of PNPB with Z-C6H4C(Me)=NO- gives a small but definitely positive ρ- value (+0.09). However, for reactions of C6H5CO2C6H4-Y with EtO-, correlation of log k with σ- (Y) constant gives very poor Hammett correlation. A significantly improved linearity has been obtained when σ0 (Y) constant was used, indicating that the leaving group departure is little advanced at the TS of the RDS. For reactions of X-C6H4CO2C6H4-4-NO2 with EtO-, C6H5O- and C6H5C(Me)=NO-, correlations of log k with σ (X) constants for all the three nucleophile systems give good linearity with large positive ρ values, e.g. 2.95, 2.81 and 3.06 for EtO-, C6H5O- and C6H5C(Me)=NO-, respectively. The large ρ values clearly suggest that the present reaction proceeds via a stepwise mechanism in which the formation of the addition intermediate is the RDS.

Studies on the Physiological Characteristics of (Cervus e. canadensis) Velvet Antler in Elk

  • Jeon, Byong-Tae;Thomas, David G.;Cheong, Sun-Hee;Kim, Myeong-Hwa;Kim, Sung-Jin;Sung, Si-Heung;Park, Pyo-Jam;Park, Jae-Hyun;Moon, Sang-Ho
    • Journal of Animal Science and Technology
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    • v.52 no.3
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    • pp.237-244
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    • 2010
  • In order to investigate the physiological properties of velvet antler of elk (Cervus e. canadensis) raised in Korea, antlers (n=378) were collected from deer in 8 provinces including Gyeonggi-do (n=53), Gangwon-do (n=49), Chungcheongbuk-do (n=62), Chungcheongnam-do (n=68), Jeollabuk-do (n=52), Jeollanam-do (n=15), Gyeongsangbuk-do (n=30) and Gyeongsangnam-do (n=49). The exterior characteristics (weight, length, girth and crown) of all antlers were measured, and 18 antler samples were randomly selected for measurement of interior characteristics such as specific gravity, capacity and diameter of cross section. The mean antler weight, length of the main beam and mean length of upper section were $4.87{\pm}1.79\;kg$, $83.7{\pm}13.2\;cm$ and $40.6{\pm}11.4\;cm$, respectively. Mean girth of the top, middle and base of the main beam were $27.1{\pm}5.9\;cm$, $22.1{\pm}3.6\;cm$ and $22.9{\pm}3.6\;cm$ respectively, indicating a slight narrowing in the middle of the antler. In each of the tines, the girth at the base was markedly thicker compared to the top. The depth of the crown at the top of the antler, and the average number of crowns and tines were $14.1{\pm}7.0\;cm$, $2.1{\pm}0.6$ and $3.0{\pm}0.5$, respectively. Although there was no significant difference in mean specific gravity between top and base, mean specific gravity of main beam tended to increase from top to base of the antler with decreasing capacity. Additionally, the inner diameter of the base of the antler was significantly reduced compared to that of the top, indicating a greater integumental thickening due to mineralization. Information on the morphological and physiological properties of elk antlers is scarce. Therefore, these results may be useful in providing basic information for the physiological properties of antler, and encourage further studies on antler morphology in other deer species showing species specific differences.

Biochemical Changes of Dissimilation and Assimitation in Zoysia japonica Steud during the Regrowth Process after mowing (한국잔디(Zoysia japonica Steud.)의 예초후 재생과정에 따른 이화적, 동화적 생화학변화에 관한 연구)

  • 장남기;김형기;유준희;김용진;임채성
    • Asian Journal of Turfgrass Science
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    • v.1 no.1
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    • pp.56-68
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    • 1987
  • During the regrowth the process after mowing, NRA in the leaf was the highest activity from the 5th day to the 7th day. Before mowing, the NRA in the root was not almost detected. But, the NRA in root appeared a rapid increasing activity from the 3rd day to the 4th day after mowing ( Figs.27 ~ 32). During the regrowth process after mowing, a general tendency of AA in the aboveground parts appeared an increasing tendency from the 1st day to the 4th day, a rapid increasing tendency from the 7th day to the 8th day reaching its peak, and a decreasing rate on the 8th and 9th day reaching its peak, and a decreasing rate on the 8th and 9th day. But the AA in the root appeared rapid increasing rate from the 2nd day to the 7th day, the heginning of reagrowth, this tendency showed a similar figure in the case of Total Soluble Carbohydrate ( TSC) in the internode. Both AA and NRA were appeared recovery stage frorn the 8th day after mowing(Figs.15~20). During the regrowth process after mowing, changes of the maximum plant lengths were 18.27cm in the 6cm mowing plot on the 24th day after mowing, 18.83cm in the 3cm mowing plot on the 18th day after mowing, and 18.16cm in the 6cm mowing plot on the 14th day after mowing ( Fig.2). During the regrowth process after mowing. changes in Dry Matter (DM) contents in leaf and stem were a slow decreasing tendency from the 1st day to the 4th day. From the 5th day to the 8th day it appeared a rapid increasing tendency. And afterward until the 15th day. All treatments were reached at a steady state ( Figs.3 ~ 8). During the regrowth process after mowing, changes in the TSC contents of stem and crown were a slow decreasing tendency from the 1st day to the 5-6th day. Prom the 7th to the 8th day three was a rapid increasing tendency. And afterward until the 15th day there was a decreasing rate at a steadyv state. In root there was a similar tendency to that of leaf and stem organs. A general tendency in internode, the TSC content appeared a similar figure to increment of AA (Figs. 9 - 14). During the regrowth process after mowing, changes in te Crude Proem (CP) content of ahoveground parts appeared a slow increasing tendency from the 1st day to the 5-6th day, where it is peak. And afterward to the 15th day there was a decreasing rate at a steady state. But, in toot there were a contrary tendency to that of aboveground

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The Extraction of Metal Contaminants using Supercritical CO2 (초임계이산화탄소를 이용한 방사성 금속이온 추출)

  • Ju, Minsu;Kim, Jung-Hoon;Kang, Se-Sik
    • The Journal of the Korea Contents Association
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    • v.16 no.5
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    • pp.660-667
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    • 2016
  • Conventional decontamination methods utilize water-based systems, which generate high amounts of secondary wastes. Herein, we describe an environmentally benign decontamination method using liquid and supercritical $CO_2$. The use of $CO_2$ as a solvent affords effective waste reduction by its ability to be recycled, thereby leaving be hind only the contaminants upon its evaporation. In this study, a $CO_2$ solution process was assessed using t-salen(t-butylsalen), DC18C6 (dicyclohexano-18Crown6), 8-HQN(8-hydroxyquinoline), NEt4PFOSA(perfluoro-1-octanesulfonic acid tetra-ethyl ammonium salt), and NEt4PFOA(pentadecafluorooctanoic acid ammonium salt) to extract spiked radioactive contaminants(Nb,Zr,Co,Sr) from an inert sample matrix, namely filter paper. With the static extraction method, Sr was extracted with a maximum extraction rate of 97%, and Nb was extracted with a maximum extraction rate of 75%. Additionally, we were also able to extract Co and Zr with maximum extract ion ratesof 73% and 64%, respectively.

Metal-Ion Catalysis in Alkaline Ethanolysis of 2-Pyridyl Thionobenzoate: Effects of Modification of Electrophilic Center from C=O to C=S

  • Um, Ik-Hwan;Song, Yoon-Ju;Kim, Min-Young;Lee, Jae-In
    • Bulletin of the Korean Chemical Society
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    • v.34 no.5
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    • pp.1525-1529
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    • 2013
  • Pseudo-first-order rate constants ($k_{obsd}$) have been measured spectrophotometrically for the nucleophilic substitution reactions of 2-pyridyl thionobenzoate (5b) with alkali-metal ethoxides (EtOM, $M^+=Li^+$, $Na^+$, $K^+$, and 18-crown-6-ether complexed $K^+$) in anhydrous ethanol at $25.0{\pm}0.1^{\circ}C$. The plots of $k_{obsd}$ vs. $[EtOM]_o$ curve upward regardless of the nature of the $M^+$ ions, while those of $k_{obsd}/[EtO^-]_{eq}$ vs. $[EtO^-]_{eq}$ are linear with a positive intercept. Dissection of $k_{obsd}$ into $k_{EtO^-}$ and $k_{EtOM}$ (i.e., the second-order rate constants for the reactions with the dissociated $EtO^-$ and ion-paired EtOM, respectively) has revealed that the ion-paired EtOM is more reactive than the dissociated $EtO^-$, and $M^+$ ions catalyze the reactions in the order $K^+$ < $Na^+$ < $Li^+$ < 18C6-complexed $K^+$. The plot of log $k_{EtOM}$ vs. $1/r_{Stokes}$ results in an excellent linear correlation, indicating that the reactions are catalyzed by the solvated $M^+$ ions but not by the bare $M^+$ ions. The reactions of 5b with EtOM have been concluded to proceed through a six-membered cyclic TS, in which the solvated $M^+$ ions increase the electrophilicity of the reaction center and the nucleofugality of the leaving group.

Fruit Characteristics and Yield according to the Age of "Cheonhwang" Jujube Trees (Zizyphus jujuba var. inermis) (대추나무 '천황'의 수령에 따른 과실품질과 수확량)

  • Park, Seong-In;Chul-Woo Kim;Yoo, Hui-Won;Lee, Uk;Ahn, Young-Sang
    • Journal of Korean Society of Forest Science
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    • v.111 no.4
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    • pp.548-556
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    • 2022
  • In this study, basic data were obtained to determine the optimal cultivation method to achieve stable fruiting and yield increase in "Cheonhwang" jujube trees. Accordingly, thefructification, fruit characteristics, and yield according to tree age were analyzed. The mean (and range of) tree height, crown area, stem diameter near the root, clear stem length, number of main branches, and distance between main branches were 235.6 (217.4-253.8) cm, 3.5 (3.1-4.1) m2, 5.5 (4.0-7.1) cm, 70.6 (66.2-72.7) cm, 9.7 (8.6-10.5), and 10.4 (7.9-14.2) cm, respectively. Correlationanalysis results indicated that tree age was positively correlated with crown area, stem diameter near the root, and clear stem length but not with the number of main branches. The mean number (and range) of fruit per fruit-bearing mother shoot and tree were 18.3 (16.7-18.3) and 170.7 (157.9-178.3), respectively. Tree age was not significantlycorrelated with fruiting characteristics (i.e., the numbers of fruit-bearing mother shoots per main branch, fruit-bearing shoots per fruit-bearing mother shoot, fruit per fruit-bearing shoot, and fruit per tree). Given that the shape of jujube trees is constantly managed according to the growing area and greenhouse type, the tree growth characteristics were more affected by tree management techniques than by tree age. The mean (and range of) fruit weight, fruit hardness, and soluble solid content were 28.6 (27.7-30.3) g, 29.4 (28.5-30.4) N, and 20.4 (19.3-21.0) °brix, respectively, and these fruit characteristics were not significantly correlated with tree age.The average yield per tree of the 'Cheonhwang' jujube cultivar was 4.9 (4.8-5.0) kg, which was not significantly correlated with tree age.