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The Correction Factor of Sensitivity in Gamma Camera - Based on Whole Body Bone Scan Image - (감마카메라의 Sensitivity 보정 Factor에 관한 연구 - 전신 뼈 영상을 중심으로 -)

  • Jung, Eun-Mi;Jung, Woo-Young;Ryu, Jae-Kwang;Kim, Dong-Seok
    • The Korean Journal of Nuclear Medicine Technology
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    • v.12 no.3
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    • pp.208-213
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    • 2008
  • Purpose: Generally a whole body bone scan has been known as one of the most frequently executed exams in the nuclear medicine fields. Asan medical center, usually use various gamma camera systems - manufactured by PHILIPS (PRECEDENCE, BRIGHTVIEW), SIEMENS (ECAM, ECAM signature, ECAM plus, SYMBIA T2), GE (INFINIA) - to execute whole body scan. But, as we know, each camera's sensitivity is not same so it is hard to consistent diagnosis of patients. So our purpose is when we execute whole body bone scans, we exclude uncontrollable factors and try to correct controllable factors such as inherent sensitivity of gamma camera. In this study, we're going to measure each gamma camera's sensitivity and study about reasonable correction factors of whole body bone scan to follow up patient's condition using different gamma cameras. Materials and Methods: We used the $^{99m}Tc$ flood phantom, it recommend by IAEA recommendation based on general counts rate of a whole body scan and measured counts rates by the use of various gamma cameras - PRECEDENCE, BRIGHTVIEW, ECAM, ECAM signature, ECAM plus, IFINIA - in Asan medical center nuclear medicine department. For measuring sensitivity, all gamma camera equipped LEHR collimator (Low Energy High Resolution multi parallel Collimator) and the $^{99m}Tc$ gamma spectrum was adjusted around 15% window level, the photo peak was set to 140-kev and acquirded for 60 sec and 120 sec in all gamma cameras. In order to verify whether can apply calculated correction factors to whole body bone scan or not, we actually conducted the whole body bone scan to 27 patients and we compared it analyzed that results. Results: After experimenting using $^{99m}Tc$ flood phantom, sensitivity of ECAM plus was highest and other sensitivity order of all gamma camera is ECAM signature, SYMBIA T2, ECAM, BRIGHTVIEW, IFINIA, PRECEDENCE. And yield sensitivity correction factor show each gamma camera's relative sensitivity ratio by yielded based on ECAM's sensitivity. (ECAM plus 1.07, ECAM signature 1.05, SYMBIA T2 1.03, ECAM 1.00, BRIGHTVIEW 0.90, INFINIA 0.83, PRECEDENCE 0.72) When analyzing the correction factor yielded by $^{99m}Tc$ experiment and another correction factor yielded by whole body bone scan, it shows statistically insignificant value (p<0.05) in whole body bone scan diagnosis. Conclusion: In diagnosing the bone metastasis of patients undergoing cancer, whole body bone scan has been conducted as follow up tests due to its good points (high sensitivity, non invasive, easily conducted). But as a follow up study, it's hard to perform whole body bone scan continuously using same gamma camera. If we use same gamma camera to patients, we have to consider effectiveness of equipment's change by time elapsed. So we expect that applying sensitivity correction factor to patients who tested whole body bone scan regularly will add consistence in diagnosis of patients.

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A Comparative Study of the Standard Uptake Values of the PET Reconstruction Methods; Using Contrast Enhanced CT and Non Contrast Enhanced CT (PET/CT 영상에서 조영제를 사용하지 않은 CT와 조영제를 사용한 CT를 이용한 감쇠보정에 따른 표준화섭취계수의 비교)

  • Lee, Seung-Jae;Park, Hoon-Hee;Ahn, Sha-Ron;Oh, Shin-Hyun;NamKoong, Heuk;Lim, Han-Sang;Kim, Jae-Sam;Lee, Chang-Ho
    • The Korean Journal of Nuclear Medicine Technology
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    • v.12 no.3
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    • pp.235-240
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    • 2008
  • Purpose: At the beginning of PET/CT, Computed Tomography was mainly used only for Attenuation Correction (AC), but as the performance of the CT have been increase, it could give improved diagnostic information with Contrast Media. But it was controversial that Contrast Media could affect AC on PET/CT scan. Some submitted thesis' show that Contrast Media could overestimate when it is for AC data processing. On the contrary, the opinion that Contrast Media could be possible to affect the alteration of SUV because of the overestimated AC. But it does not have a definite effect on the diagnosis. Thus, the affection of Contrast Media on AC was investigated in this study. Materials and Methods: Patient inclusion criteria required a history of a malignancy and performance of an integrated PET/CT scan and contrast- enhanced CT scan within a 1-day period. Thirty oncologic patients who had PET/CT scan from December 2007 to June 2008 underwent staging evaluation and met these criteria. All patients fasted for at least 6 hr before the IV injection of approximately 5.6 MBq/kg (0.15 mCi/kg) of $^{18}F$-FDG and were scanned about 60 min after injection. All patients had a whole body PET/CT performed without IV contrast media followed by a contrast-enhanced CT on the Discovery STe PET/CT scanner. CT data were used for AC and PET images came out after AC. The ROIs drew and measured SUV. A paired t-test of these results was performed to assess the significance of the difference between the SUV obtained from the two attenuation corrected PET images. Results: The mean and maximum Standardized Uptake Values (SUV) for different regions averaged over all Patients. Comparing before using Contrast Media and after using, Most of ROIs have the increased SUV when it did Contrast Enhanced CT compare to Non-Contrast enhanced CT. All regions have increased SUV and also their p value was under 0.05 except the mean SUV of the Heart region. Conclusion: In this regard, the effect on SUV measurements that occurs when a contrast-enhanced CT is used for attenuation correction could have significant clinical ramifications. But some submitted thesis insisted that the percentage change in SUV that can determine or modify clinical management of oncology patients is small. Because there was not much difference that could be discovered by interpreter. But obviously the numerical change was occurred and on the stage finding primary region, small change would be base line, such as the region of liver which has greater change than the other regions needs more attention.

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Clinical Features and the Natural History of Dietary Protein Induced Proctocolitis: a Study on the Elimination of Offending Foods from the Maternal Diet (식품 단백질 유발성 직결장염의 임상 소견과 식이 조절에 관한 연구)

  • Choi, Seon Yun;Park, Moon Ho;Choi, Won Joung;Kang, Una;Oh, Hoon Kyu;Kam, Sin;Hwang, Jin-Bok
    • Pediatric Gastroenterology, Hepatology & Nutrition
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    • v.8 no.1
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    • pp.21-30
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    • 2005
  • Purpose: The aim of this study was to identify the clinical features and natural history of dietary protein induced proctocolitis (DPIPC) and to detect the causative foods of DPIPC, and to evaluate the effect of elimination of the foods on the course of the disease. Methods: Between March 2003 and July 2004, data from 30 consecutive patients with DPIPC who were followed for over 6 months, was reviewed. The diagnostic criterion used for DPIPC was an increase in the number of eosinophils in the lamina propria (${\geq}60per$ 10 high-power fields). In breast feeding mothers, 5 highly allergenic foods were eliminated from the maternal diet for 7 days, namely, allergenic food groups such as dairy products, eggs, nuts and soybean, fish and shellfish, and wheat and buckwheat. We observed the disappearance or appearance of hematochezia after elimination or challenge with the offending foods. Results: Before diagnosis infants were breast-fed (93.3%) or formula-fed (6.7%). Mean age at symptom onset was $11.5{\pm}5.1$ (5~24) weeks, and mean age at diagnosis was $17.8{\pm}9.5$ (8~56) weeks. Duration from symptom onset to diagnosis was $6.3{\pm}6.7$ (0~36) weeks. Mean peripheral blood eosinophil count was $478{\pm}320$ (40~1,790)/$mm^3$ and eosinophilia (> $250/mm^3$) was observedin 90.0% of patients. None of patients were found to have an increased serum IgE level. Of 15 patients that received sigmoidoscopy, nodular hyperplasia with erosion was observed in 93.3%. Of 27 patients whose mother ate the diet eliminated the 5 food groups, hematochezia diappeared in 74.1% of patients. Offending foods were identified as dairy products (37.5%), wheat and buckwheat (27.5%), fish and shellfish (20.0%), nuts and soybean (7.5%) and eggs (7.5%). A free maternal diet without patient's clinical symptoms was achieved at $29.4{\pm}8.7$ (9~44) weeks of patient's age, and a free baby diet without blood in stools was achieved at $37.5{\pm}9.7$ (12~56) weeks of age. Conclusion: DPIPC commonly occurs in exclusively breast-fed babies. Elimination of the above-mentioned 5 hyper-allergenic food groups from the maternal diet for 7days enables the detection of the offending foods. DPIPC is a transient disorder and 96.0% of patients can tolerate the offending foods at 12 months of age.

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Effects of Supplementation with Transgenic Bacillus subtilis Secreting Chitinase on Growth Performance, Nutrient Digestibility, Blood Characteristics, and Carcass Traits in Finishing Pigs (키틴분해효소를 분비하는 형질전환 Bacillus subtilis의 사료내 첨가가 비육돈의 성장, 영양소 소화율, 혈액성상 및 육질특성에 미치는 영향)

  • Kim, Hyo-Jin;Cho, Jin-Ho;Chen, Ying-Jie;Yoo, Jong-Sang;Wang, Yuan;Huang, Yan;Kim, In-Ho
    • Food Science of Animal Resources
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    • v.28 no.2
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    • pp.181-186
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    • 2008
  • This study was conducted to investigate the effects of supplementation with transgenic Bacillus subtilis secreting chitinase on the growth performance, nutrient digestibility, blood characteristics and carcass traits in finishing pigs. A total of sixty-four pigs ($50.82{\pm}0.82kg$, average initial body weight) were assessed over a period of 84 days. Dietary treatments included: 1) CON (basal diet without antibiotics), 2) AD (basal diet + 0.1% Virginiamycin), 3) CD0.5 (basal diet + 0.5% transgenic B. subtilis), 4) CD1.0 (basal diet + 1.0% transgenic B. subtilis). Each dietary treatment had 4 replicates of 4 pigs per pen in a randomized complete block design. In terms of growth performance, the ADG (average daily gain) and gain/feed ratio were significantly increased with the CD1.0 diet compared to the AD diet during weeks 0-4 (p<0.05). During weeks 4-8, the ADG was significantly increased with the AD diet compared to the CON and CD0.5 diets (p<0.05). The ADFI was also significantly increased with the AD diet compared to the other diets (p<0.05). During weeks $8{\sim}12$, the ADFI was significantly increased with the CON diet compared to the other diets (p<0.05), and the gain/feed ratio was significantly increased with the CD0.5 and CD1.0 diets compared to the AD diet (p<0.05). Over the entire 84 day test period, the ADFI was significantly increased with the AD diet compared to the CD0.5 and CD1.0 diets (p<0.05). The gain/feed ratio was significantly increased with the CD0.5 and CD1.0 diets compared to the CON diet (p<0.05). In terms of meat color, the L value was significantly increased with the CD0.5 diet compared to the CON and AD diets (p<0.05), and the a value was significantly increased with the CON diet compared to the other diets (p<0.05). In terms of sensory evaluation, meat color was significantly improved with the CON, CD0.5 and CD1.0 diets compared to the AD diet (p<0.05). Marbling was significantly increased with the CON diet compared to the other diets (p<0.05). Firmness was significantly increased with the CD0.5 diet compared to the AD diet (p<0.05). In conclusion, supplementation with transformed B. subtilis secreting chitinase improved gain/feed ratios and influenced meat color. Thus, we suggest that transformed B. subtilis secreting chitinase can partially substitute for antibiotics.

Mitral Valve Repair for Mitral Regurgitation in Pediatric Patients (승모판폐쇄부전증를 가진 소아 환자에서 승모판성형술의 임상적 고찰)

  • Sim, Hyung-Tae;Yun, Tae-Jin;Park, Jeong-Jun;Jung, Sung-Ho;Uhm, Ju-Yeon;Jhang, Won-Kyoung;Kim, Young-Hwue;Ko, Jae-Kon;Park, In-Sook;Seo, Dong-Man
    • Journal of Chest Surgery
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    • v.40 no.8
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    • pp.536-545
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    • 2007
  • Background: Compared to adult patients, mitral regurgitation in pediatric patients is uncommon and it shows a wide spectrum of morphologic abnormalities. We retrospectively evaluated the midterm results of mitral valve repair in pediatric patients. Material and Method: Between December 1993 and August 2006, mitral valve repair was performed in 35 patients who were aged less than 18 years, The mean age was $5.3{\pm}5.3$ years and the mean body weight was $20,0{\pm}16.3\;kg$. 18 patients had associated cardiac anomalies. The most common pathologic finding was leaflet prolapse (n=17). The most common method of repair was the double orifice technique (n=15). Result: There was no early mortality. Eight patients underwent reoperation (24.2%), and five of them required mitral valve replacement. Among the four ring annuloplasty cases, two have developed mitral stenosis. Four out of the 14 double orifice cases required reoperation. One case of early mortality and one case of late mortality occurred in the reoperation cases. The 5-year survival rate and the freedom from reoperation rate were $93.3{\pm}4.6%$ and $76.1{\pm}8.2%$, respectively. The 5-year freedom from mitral valve replacement rate was $83.6{\pm}6.7%$. There was no significant risk factor for reoperation. Conclusion: The midterm results of mitral valve repair are very acceptable in pediatric patients compared to the adult cases, although the reoperation rate is slightly higher.

Studies on the Induction of Available Mutants of Takju Yeast by UV light Irradiation (part 2) -On the Physiological Characteristics of the Mutants- (자외선조사(紫外線照射)에 의한 탁주효모(酵母)의 변이주육성(變異株育成)에 관한 연구 (제 2 보) -변이주(變異株)의 생리적성질(生理的性質)에 관하여)

  • Kim, Chan-Jo;Oh, Man-Jin;Kim, Seung-Yul
    • Applied Biological Chemistry
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    • v.18 no.1
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    • pp.16-22
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    • 1975
  • This experiment was carried out to investigate the physiological characteristics of two original yeasts, 5-Y-5 and 6-Y-6, which selected from 24 Takju yeasts and three mutants, 30-24,30-81 and 40-27. induced from two original yeasts by the irradiation of UV light. The results were summarized as follows. 1) Alcohol tolerances of three mutants were decreased in some degree as compared with those of original yeasts. 2) Tolerances of lactic and citric acids of acid producing mutant 30-81, was increased than those of original yeasts. 3) In the case of using ammonium sulfate as a nitrogen source, two original yeasts and three mutants required Ca-pantothenate as a essential growth factor and four strains of yeasts except the mutant, 30-81, required biotin as a stimulated growth factor, When asparagine was used as a nitrogen source, two original yeasts and three mutants showed the same as above result but the stimulated effect of biotin was far less. 4) Propagation powers of the mutants were weaken than those of original yeasts, particular that of acid producing mutant, 30-81, was the weakest in the three mutants. 5) The optimum temperature for fermentation of original yeasts were $30^{\circ}C\;to\;35^{\circ}C$ but three mutants were $25^{\circ}C\;to\;30^{\circ}C$. 6) The optimum pH for fermentation of original yeasts were pH 5 to 6, and there is no appreciable difference between original yeasts and three mutants. The fermentation power of mutant,30-81, was decreased more rapidly than those of other mutants according to approach neutral. Three mutants were more sensible to heat than original yeasts. 7) Two original yeasts and three mutants were inhibited more over 20 percent of sugar for fermentation and three mutants were more sensible to sugar concentration than original yeasts.

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Studies on the Effect of Low Temperature Treatment at Meiotic, Heading and Seedling Stage in Paddy Rice (수도의 장해형 냉해에 관한 연구)

  • Hong-Suk Lee;Hyung-Yull Cho;Pyeong-Ki Yim;Hoon Heu
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.15
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    • pp.85-97
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    • 1974
  • In order to clarify the inducing conditions and cause of sterility in rice plants, 4 varieties were cooled at 3 different levels of temperature combined with 3 different levels of treatment period. And 19 varieties were tested to examine the varietal difference of cold resistance. The results obtained were summarized as follows; 1. There were significant varietal differences in the effect of cooling treatment at meiotic stage. Suwon 213-1 was induced heavy sterility by 3 day cooling treatment at 17.5$^{\circ}C$ whereas Hayayuki, Nongpaik and Jinheung were induced a little sterility by 3 day cooling treatment at 15$^{\circ}C$ and 5 day treatment at 17.5$^{\circ}C$. The per cent of grain fertility was correlated significantly with the delayed days to heading, the degree of panicle extraction (Suwon 213-1, Nongpaik, Jinheung), culm length (Nongpaik, Suwon 213-1), and Auricle distance (Suwon 213-1). The degree of sterility was able to be estimated from the linear regression equation between the degree of panicle extraction (distance from panicle neck to flag leaf) and fertility percentage. In the case of heavy cold damage by the treatment of low temperature at meiotic stage, the rice plant had somewhat lower pollen density per anther, small and ununiform anther and pollen in size, and more sterile pollen grains. Suwon 213-1 showed anthesis in almost all spikelets, while Nongpaik, Jinheung and Hayayuki indicated considerable number of indehisced anther at 5 days after heading. 2. The fertility were not generally higher in cooling treatment at heading stage than at meiotic stage treatment. And significant correlation was found between the percentage of grain fertility treated at above two stages. Nongpaik and Jinheung were not affected in percentage of fertility by 5 day treatment at 15$^{\circ}C$ when these were treated at heading stage. Indehisced anthers were not found in Suwon 213-1 and Hayayuki, but Nongpaik and Jinheung showed more anthers which did not show anthesis 3. There was different varietal response to low temperature which was indicated by the decrease of grain fertility resulted from cooling treatment at meiotic stage. Jaekeun and Jinheung did not show low fertility but Milseong, Suwon 210, Satominoli and Suwon 213-1 showed outstanding decrease in fertility percentage by the cooling treatment at meiotic stage. The varieties which had low fertility were likely to have low pollen density per anther, abnormal anthers, small size po]]en grains and many sterile pollens. 4. Remarkable varietal difference of cold resistance was found in heading stage cooling treatment. Nongpaik, Jinheung, Jaekeun, Paltal, Akibare, Milseung and Palkeong were not affected in grain fertility by cooling treatments but Nonglimna No. 1, Suseong, Hayayuki, Suwon 213-1 and Suwon 210 showed significantly high sterility as treated by cool temperature. Most of the varieties showed higher fertility by cooling treatment at heading stage than meiotic stage but Hayayuki, Suseong and Nonglimna No.1 showed lower fertility when these were treated at heading stage than meiotic stage. There were two grops of varieties in the response to cooling treatment, one was somewhat non-anthesised and the other showed full anthesis. 5. In cold injury test of young seedlings, the result of observation was not accorded with the degree of growth inhibition. As a general, Palkeum and Suseong were highly torelant to cool temperature but Suwon 213-1, Jaekeun, Paltal, Shirogane, Palkeong, Mankyung were highly susceptible. 6. There is no significant correlation between the degree of young seedling cold damage and or the degree of growth retardation at seedling stage and grain fertility resulted from coding treatment both heading and meiotic stage.

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Change of Seed Dormancy and Viability of Chinese Milk Vetch (Astragalus sinicus L.) in Rice Field (토양속에서 자운영 종자의 휴면성 및 종자활력 변화)

  • Kim, Sang-Yeol;Hwang, Woon-Ha;Lee, Jong-Hee;Oh, Seong-Hwan;Cho, Jun-Hyeon;Han, Sang-Ik;Jeong, Kuk-Hyun;Park, Sung-Tae;Choi, Kyung-Jin;Kim, Jeong-Il;Lee, Ji-Yoon;Song, You-Cheon;Yeo, Un-Sang;Kang, Hang-Won
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.55 no.1
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    • pp.76-82
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    • 2010
  • Experiments were conducted to investigate seed persistence of Chinese milk vetch(CMV) in naturally reseeded rice field in 2007~2009. The seed and pods with seeds were buried in rice field at 0, 5 and 10 cm depths and retrieved from the field at one to three month intervals from July to the following year March and determined change of seed dormancy and viability. In the second experiment, persistence of the CMV seeds in the naturally reseeded rice field at different tillage methods and soil depths were also investigated after rice harvest in autumn. Burial depths and durations affected recovery rate, dormancy and viability of CMV seed. The viability loss was faster and greater in the seed than the pod with seeds and on the soil surface than the 5 or 10 cm burial depths. The recovery rate of CMV seed was decreased starting from one month as seed burial and it was significantly decreased to 52~65% for the seed in September. However, unlike the seed burial, the nearly 100% CMV seeds were recovered for burial as pod with seeds even after four months burial in both 0 and 5 cm depths. However, the recovery rate was sharply declined to below 30% at October in 2007 in both seed and pods with seeds and in the 2008/2009 experiment. the 15~47% of CMV seeds still remained even after October. The CMV had high seed dormancy of 95%, showing only 4~5% germination at the beginning in June but the seed germination increased to 25 to 35% in seed and 55 to 61% in pod with seeds in September due to breakage of hard seed dormancy. The viability loss was faster in the seed than in the pod with seeds regardless of depths of placement in the soil base on decayed seeds. Also the seed placed on the soil surface lost viability faster than the 5~10 burial depths. On the other hand, field observation in the naturally reseeded CMV rice field showed that as many as 917~2,185 CMV seeds $m^2$ were from the 0~15 cm soil depth in the rotary tillage and 250~10,105 CMV seeds in minimum tillage treatmints. The recovered seed germinated 25~33%, 23~43% but still had high percentage of hard seed having 64~72% and 51~77% even after rice harvest in autumn. These results indicate that freshly harvested CMV seeds had high level of primary dormancy and the dormancy was gradually broken in soil with time during rice cultivation periods and appreciable number of CMV seeds remained even 4 month after burial in soil. CMV plant regenerated naturally from the remained seed bank at rice harvest time in autumn. The CMV seedling still emerged even after 2 years of continuous destructive killing of emerged CMV plant by rotary tillage in naturally reseeded CMV plant in rice field, indicating that CMV seeds do persistent as least two years in soil.

Temporal Variations of Ore Mineralogy and Sulfur Isotope Data from the Boguk Cobalt Mine, Korea: Implication for Genesis and Geochemistry of Co-bearing Hydrothermal System (보국 코발트 광상의 산출 광물종 및 황동위원소 조성의 시간적 변화: 함코발트 열수계의 성인과 지화학적 특성 고찰)

  • Yun, Seong-Taek;Youm, Seung-Jun
    • Economic and Environmental Geology
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    • v.30 no.4
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    • pp.289-301
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    • 1997
  • The Boguk cobalt mine is located within the Cretaceous Gyeongsang Sedimentary Basin. Major ore minerals including cobalt-bearing minerals (loellingite, cobaltite, and glaucodot) and Co-bearing arsenopyrite occur together with base-metal sulfides (pyrrhotite, chalcopyrite, pyrite, sphalerite, etc.) and minor amounts of oxides (magnetite and hematite) within fracture-filling $quartz{\pm}actinolite{\pm}carbonate$ veins. These veins are developed within an epicrustal micrographic granite stock which intrudes the Konchonri Formation (mainly of shale). Radiometric date of the granite (85.98 Ma) indicates a Late Cretaceous age for granite emplacement and associated cobalt mineralization. The vein mineralogy is relatively complex and changes with time: cobalt-bearing minerals with actinolite, carbonates, and quartz gangues (stages I and II) ${\rightarrow}$ base-metal sulfides, gold, and Fe oxides with quartz gangues (stage III) ${\rightarrow}$ barren carbonates (stages IV and V). The common occurrence of high-temperature minerals (cobalt-bearing minerals, molybdenite and actinolite) with low-temperature minerals (base-metal sulfides, gold and carbonates) in veins indicates a xenothermal condition of the hydrothermal mineralization. High enrichment of Co in the granite (avg. 50.90 ppm) indicates the magmatic hydrothermal derivation of cobalt from this cooling granite stock, whereas higher amounts of Cu and Zn in the Konchonri Formation shale suggest their derivations largely from shale. The decrease in temperature of hydrothermal fluids with a concomitant increase in fugacity of oxygen with time (for cobalt deposition in stages I and II, $T=560^{\circ}C-390^{\circ}C$ and log $fO_2=$ >-32.7 to -30.7 atm at $350^{\circ}C$; for base-metal sulfide deposition in stage III, $T=380^{\circ}-345^{\circ}C$ and log $fO_2={\geq}-30.7$ atm at $350^{\circ}C$) indicates a transition of the hydrothermal system from a magmatic-water domination toward a less-evolved meteoric-water domination. Sulfur isotope data of stage II sulfide minerals evidence that early, Co-bearing hydrothermal fluids derived originally from an igneous source with a ${\delta}^{34}S_{{\Sigma}S}$ value near 3 to 5‰. The remarkable increase in ${\delta}^{34}S_{H2S}$ values of hydrothermal fluids with time from cobalt deposition in stage II (3-5‰) to base-metal sulfide deposition in stage III (up to about 20‰) also indicates the change of the hydrothermal system toward the meteoric water domination, which resulted in the leaching-out and concentration of isotopically heavier sulfur (sedimentary sulfates), base metals (Cu, Zn, etc.) and gold from surrounding sedimentary rocks during the huge, meteoric water circulation. We suggest that without the formation of the later, meteoric water circulation extensively through surrounding sedimentary rocks the Boguk cobalt deposits would be simple veins only with actinolite + quartz + cobalt-bearing minerals. Furthermore, the formation of the meteoric water circulation after the culmination of a magmatic hydrothermal system resulted in the common occurrence of high-temperature minerals with later, lower-temperature minerals, resulting in a xenothermal feature of the mineralization.

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A Study on Synergisitic Effect of Chitosan and Sorbic Acid on Growth Inhibition of Escherichia coli O517:H7 and Staphylococcus aureus (E. coli O517:H7 과 Staphylococcus aureus의 증식억제에 대한 키토산과 소르빈산의 상승효과에 관한 연구)

  • 조성범;이용욱;김정현
    • Journal of Food Hygiene and Safety
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    • v.13 no.2
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    • pp.112-120
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    • 1998
  • This study was performed to investigate the synergistic effect of chitosan and sorbic acid as a new food preservative. So it was performed to investigate inhibitory effect on growh of E. coli 0157:H7, gram negative pathogenic food borne disease bacteria and of S. aureus, gram positive food borne disease bacteria in chitosan, sorbic acid and combination of chitosan and sorbic acid. Minimun Inhibitory Concentration (MIC) of chitosan in E. coli 0157:H7 was 500 ppm at pH 5.0, 250 ppm at pH 5.5, 500 ppm at pH 6.0, and 2000 ppm at pH 6.5, while in Staph. aureus 31.25 ppm at pH 5.0 and 62. 5 ppm at more than pH 5.5. also, MIC of sorbic acid in E. coli 0157:H7 was 500 ppm at pH 5.0, 1500 ppm at pH 5.5, and 2000 ppm at more than pH 6.0, while in Staph. aureus 1500 ppm at pH 5.0 and more than 2000 ppm at more than pH 5.5. Due to the effect of pH in E. coli 0157:H7, MIC of combined chitosan and sorbic acid was 500 ppm of chitosan with 500 ppm of sorbic acid at pH 6.5, but 250 ppm of chitosan with 31.3 ppm of sorbic acid at pH 5.0. In Staph. aureus, there was great effect of chitosan, but neither effect of pH nor sorbic acid. When E. coli 0157:H7 were treated with 500 ppm of chitosan with 500 ppm of sorbic acid and 250 ppm of chitosan with 250 ppm of sorbic acid at pH 6.5, they were inhibited. But, they were increased at the initial concentration of bacteria at 1000 ppm of chitosan in 18 hours, at 500 ppm of chitosan in 36 hours. There was no effect of growth inhibition with sorbic acid but great effect with chitosan on Staph. aureus. The correl~tions between MICs of chitosan and sorbic acid in E. coli 0157:H7 accoding to pH were higher than those in Staph. aureus. R values in E. coli 0157:H7 were 0.95 (p<0.01), 0.99 (p<0.01), 0.97 (p<0.01), and 0.99 (p<0.01) at pH 6.5, 6.0, 5.5, and 5.0 respectively. The synergistic effect of chitosan and sorbic acid in E. coli 0157:H7 could be confirmed from the result of this experiment. Therefore, it was expected that the food preservation would increase or maintain by using sorble acid together with chitosan, natural food additive that did no harm to human body.

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