• Korean Journal of Soil Science and Fertilizer
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• v.34 no.4
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• pp.255-264
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• 2001

This study was conducted to investigate changes in inorganic phosphorus fractions in phosphorus accumulated plastic film house soils under cropping condition. Pot experiment was conducted with surface soils taken from plastic film house fields cultivated for 3, 8 and 16 years. Phosphorus fertilizer was applied at the rates of 0 (P0), $100kg\;ha^{-1}$ (recommended application rate. P1) and $200kg\;ha^{-1}$ (P2) as fused phosphate. Crops were grown sequentially in the order of corn-Chinese cabbage-Chinese cabbage-corn for 3 years. The content of easily soluble-P fraction was decreased with cropping. There were significantly positive relationship not only between the contents of easily soluble-P and the amounts of soil available P ($r=0.839^{**}{\sim}0.952^{**}$ for Bray-1 P, $r=0.895^{**}{\sim}0.967^{**}$ for Lancaster P, and $r=0.491^{**}{\sim}0.821^{**}$ for Olsen P), but also between the amounts of P absorbed by plants and the amounts of easily soluble P decreased ($r=0.644^{**}{\sim}0.822^{**}$). The decrease of easily soluble-P during cropping period could be described by a first-order reaction. The number of cropping times needed to decrease the content of easily soluble-P to an index level of $0.2mg\;kg^{-1}$, which is commonly reported as the desired concentration for soil P, was predicted in the range of 26~33 cropping times by using the equations. Regardless of P fertilization, the proportion of Al-P to total P was little varied during cropping period, but the proportion of Fe-P to total P increased with cropping. Although the content of Ca-P was high before cropping, the proportion of Ca-P to total P was increased with cropping. The proportion of reductant soluble-P to total P was little varied for P fertilizer treatment but was increased for no P fertilizer treatment. The residual-P was decreased during cropping period due to the absorption by crops and the conversion to other inorganic P fractions.

• Korean Journal of Environmental Agriculture
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• v.31 no.3
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• pp.248-254
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• 2012

BACKGROUND: In order to elucidate residual characteristics of difenoconazole and thiamethoxam by treatment to sweet persimmons for one year and to generate the data for the maximum residue limit (MRL) establishment for those pesticides in or on sweet persimmon. METHODS AND RESULTS: Systemic fungicide difenoconazole WP (10% a.i.) and systemic insecticide thiamethoxam WG (10% a.i.) were sprayed onto 12~25-years-old sweet persimmons according to its preharvest interval (PHI), respectively, and then fresh sweet persimmons were harvested at 0, 1, 3, 7, 14, 21 days after treatment from pesticide-sprayed plots at each 3 sites. The analytical methods were evaluated to limit of quantification, linearity, specificity, reproducibility and recoveries. The crop samples were extracted with acetone and performed dichloromethane partition process. The extracted samples of difenoconazole were analyzed by GC-ECD and the thiamethoxam extracted samples were analyzed by HPLC with good sensitivity and selectivity of the method. The average recoveries of difenoconazole ranged from 87.5 to 99.5% with the percentage of coefficient variation in the range 4.1~7.6% at three different spiking levels(0.02, 0.2 and 2.0 mg/kg). And the average recoveries of thiamethoxam and clothianidin ranged from 88.8 to 98.9% and 83.2 to 96.6% with the percentage of coefficient variation in the range 3.6~5.0% and 3.8~9.4% at three different spiking levels(0.02, 0.2 and 2.0 mg/kg), respectively. The residue amounts ranges of difenoconazole were 0.2~0.56 mg/kg and the residue amount was decreased below the MRL level, 1.0 mg/kg, after 1 day harvest. The residue amounts ranges of thiamethoxam were 0.08~0.28 mg/kg and the residue amount was decreased below the MRL level, 0.5 mg/kg, after 1 day harvest. And the residue amount of clothianidin was below then 0.03 mg/kg for only one test site of 14 and 28 day samples. CONCLUSION: As a result, the residual amounts of difenoconazole and thiamethoxam were not exceeded the MRL of established criteria for sweet persimmon. The biological half-lives of difenoconazole and thiamethoxam were 13.6, 19.4, 16.3 and 10.0, 15.3, 14.0 days at each three test sites, respectively.

• Korean Journal of Environmental Agriculture
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• v.14 no.3
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• pp.289-295
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• 1995

This study was carried out to develop a controlled-release insecticide formulation for the control of rose aphid (Macrosiphum ibarae) in rose and cotton aphid (Myzus persicae) in chrysanthemum (Dendranthema grandiflorum var. Meibung) in greenhouse. Imidacloprid[1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] was chosen as a toxicant. Two synthetic polymers, low density polyethylene(LDPE) and ethylene vinyl acetate(EVA), were used as polymer matrices. The tested plastic sheet formulations were prepared by heat-aided extrusion procedures after mixing imidacloprid technical and the polymers of three different combinations, and physicochemical properties as well as efficacy of the formulations were investigated. The amounts of imidacloprid recovered and incorporated in the formulations were recorded over 90% and 80%, respectively. Release of the active ingredient from the formulations was remarkably affected by mixing rates of polymers. The active ingredient in the formulations was chemically unstable with over 10% degradation rates after 90 day storage at $50{\pm}2^{\circ}C$. The residual amounts of imidacloprid in the soil treated with the formulations were paralleled with the release pattern of the formulations. Efficacy of the formulations on rose and cotton aphid was maintained over 90% even 120days after treatment under greenhouse.

• Journal of Food Hygiene and Safety
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• v.24 no.2
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• pp.182-187
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• 2009

The reduction rate of pesticide residues on spinach(bifenthrin, metalaxyl, procymidone), chard(bifenthrin, imidacloprid) and mallow(bifenthrin, chlorpyrifos, imidacloprid) were tested on each step of washing and boiling(spinach: 1, 3, 5min., chard: 3, 6, 9min., mallow: 10, 20, 30min.). The reduction rates of bifenthrin and procymidone by washing were $58{\sim}64%$ and 82%, and these were not changed significantly after boiling. In case of imidacloprid, the rates showed 43% on chard and 12% on mallow by washing, and these were highly increased to 94% after boiling. And the reduction rate of metalaxyl and chloropyrifos were 69% and 11% by washing, and $96{\sim}98%$ and $77{\sim}79%$ by boiling. Specifically we monitored the pesticide residues on both boiled vegetable and its water because there are used to cook as soup in Korea. The total residual amounts of imidacloprid and chloropyrifos were effectively removed on both boiled mallow and its water ($12%{\rightarrow}34{\sim}40%$, $11%{\rightarrow}76{\sim}79%$), however, the other tested pesticides were not changed on pesticide residues when calculated with total amounts on boiled vegetable and its water. These explained the other pesticides were just moved vegetable to water by boiling.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.7
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• pp.970-975
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• 2009

The residual amount of 160 kinds of pesticide for multi-analysis methods were analyzed in Baechu cabbages throughout the year by GC/MS. We investigated the 160 kinds of pesticide residues in commercial Baechu cabbages monthly from October 2007 to September 2008. Over the 12 months, the residues were detected in the Baechu cabbages harvested and distributed only in July, August, October and November. The residual amounts were 0.01 ppm Bifenthrin, 0.04 ppm Chlorfenapyr, and 0.03 ppm Bifenthrin in July, October, and November, respectively, and 0.01 2 ppm Bifenthrin in August. All residues were below MRL. These results indicate that the commercial Baechu cabbages are comparatively safe from pesticide residues.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.4
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• pp.293-300
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• 2011

Purpose: Substance P is a well known neurotransmitter and has been known to mediate pain. Recently, it has been unveiled that substance P is involved in the recruitment of mesenchymal stem cells to wound sites. The purpose of this study was to exam bone formation when a combination of substance P and silk fibroin was used in a bone defect model. Methods: Twenty rabbits were used and 40 calvarial defects were formed. They were divided as 4 groups (unfilled control, silk only, silk+$10{\mu}g$/ml substance P; Sub10, and silk+$100{\mu}g$/ml substance P; Sub100). All animals were humanely sacrificed 4 or 8 weeks after grafting. The specimens were analyzed by micro-computerized tomography and histological analysis. Results: When compared to the unfilled control to silk only group, there was significant difference in bone mineral density (BMD) and the attenuation coefficient (AC) at 4 weeks ($p$=0.037 and 0.038, respectively). When compared Sub10 group to Sub100 group, there was significant difference in BMD and AC at 8 weeks ($p$=0.004 for all). Residual graft amounts were $52.1{\pm}15.8$%, $15.2{\pm}9.2$% and $9.0{\pm}3.3$% for silk only, Sub10, and Sub100 groups, respectively. When comparing the residual graft amount of silk only to sub10 or sub100, the differences were statistically significant ($p$ <0.001). Conclusion: The silk fibroin scaffold showed higher BMD and AC than the unfilled control. The combination graft with substance P and silk fibroin scaffold showed a faster graft degradation than with a silk fibroin scaffold only.

• Journal of Periodontal and Implant Science
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• v.49 no.6
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• pp.382-396
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• 2019

Purpose: The purpose of this study was to elucidate the efficacy and safety of carbonate apatite (CO₃Ap) granules in 2-stage sinus floor augmentation through the radiographic and histomorphometric assessment of bone biopsy specimens. Methods: Two-stage sinus floor augmentation was performed on 13 patients with a total of 17 implants. Radiographic assessment using panoramic radiographs was performed immediately after augmentation and was also performed 2 additional times, at 7±2 months and 18±2 months post-augmentation, respectively. Bone biopsy specimens taken from planned implant placement sites underwent micro-computed tomography, after which histological sections were prepared. Results: Postoperative healing of the sinus floor augmentation was uneventful in all cases. The mean preoperative residual bone height was 3.5±1.3 mm, and this was increased to 13.3±1.7 mm by augmentation with the CO₃Ap granules. The mean height of the augmented site had decreased to 10.7±1.9 mm by 7±2 months after augmentation; however, implants with lengths in the range of 6.5 to 11.5 mm could still be placed. The mean height of the augmented site had decreased to 9.6±1.4 mm by 18±2 months post-augmentation. No implant failure or complications were observed. Few inflammatory cells or foreign body giant cells were observed in the bone biopsy specimens. Although there were individual differences in the amount of new bone detected, new bone was observed to be in direct contact with the CO₃Ap granules in all cases, without an intermediate layer of fibrous tissue. The amounts of bone and residual CO₃Ap were 33.8%±15.1% and 15.3%±11.9%, respectively. Conclusions: In this first demonstration, low-crystalline CO₃Ap granules showed excellent biocompatibility, and bone biopsy showed them to be replaced with bone in humans. CO₃Ap granules are a useful and safe bone substitute for two-stage sinus floor augmentation.

• The Korean Journal of Pesticide Science
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• v.16 no.2
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• pp.131-136
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• 2012

This study was carried out to elucidate residual characteristics of azoxystrobin and difenoconazole in fresh ginseng. Test pesticides were sprayed onto ginseng both in 2009 for 3-year-old ginseng and in 2010 for 4-year-old ginseng according to their pre-harvest intervals (PHIs). Limit of quantitation (LOQ) of both azoxystrobin and difenoconazole was 0.003 mg/kg. Analytical methods set up for the test pesticides were considered to be suitable for the analysis of their residues in fresh ginseng, considering that their recoveries ranged from 87.58 to 112.79%. Concentration of azoxystrobin in 3-year-old ginseng ranged from 0.004 to 0.011 mg/kg and that in 4-year-old ginseng ranged from 0.007 to 0.016 mg/kg. Amounts of difenoconazole in 3- and 4-year-old ginsengs were from 0.003 to 0.007 and from 0.007 to 0.01 mg/kg, respectively, representing no accumulation effect observed in residue amount between them.

• The Korean Journal of Pesticide Science
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• v.13 no.2
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• pp.98-104
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• 2009

This study was carried out to investigate the residue patterns of two neonicotinoid insecticides, dinotefuran and thiacloprid, commonly used for cucumber, were subjected to indicate a residual characteristic under greenhouse conditions. The pesticides were sprayed onto the crop at recommended and double doses 7 days before harvest and then sampling was done 0, 2, 3, 5, and 7 days after spraying. The amounts of their residues in the crop were analyzed with an HPLC. Their detection limits were 0.01 mg/kg for dinotefuran and 0.005 mg/kg for thiacloprid. Mean recoveries of dinotefuran and thiacloprid were from 85.78 to 89.52 and from 85.71 to 95.31%, respectively. Half-lives of dinotefuran and thiacloprid were 2.8 and 1.8 days at the recommended dose and 2.8 and 1.5 days at the doubled dose, respectively. The ratios of the EDI to ADI by intake the crop harvested 7 days after spraying were less than 0.1% of their ADIs.

• Korean Journal of Food Science and Technology
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• v.42 no.1
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• pp.97-102
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• 2010

Curcuminoids are polyphenolic compounds and include curcumin and its derivatives possessing a yellow color. In the present study, changes in the chemical stability and antioxidant activities of curcuminoids, including curcumin, demethoxycurcumin (DMC), and bisdemethoxycurcumin (BMC), were investigated under various processing conditions. The yellowness of a mixture of the curcuminoids (79.4% curcumin, 16.8% DMC, and 3.8% BMC) at 405 nm was proportional to their amounts analyzed by HPLC. The curcuminoids became less stable with increases of pH and temperature during storage. Exposing a solution of the curcuminoids to autoclave conditions ($121^{\circ}C$, 1.2 atm for 15 min) decreased residual curcuminoid levels by 80-90%; however, as a powder under the same conditions the curcuminoids were much more stable with less than 10% loss. After autoclave treatment, scavenging activities of the curcuminoids for DPPH and ABTS radicals were reduced by 10.3 and 33.4%, respectively, whereas nitric oxide scavenging activity was slightly increased. The residual levels of curcumin, DMC, and BMC after autoclaving were 0.7, 1.4, and 0.9%, respectively, indicating that curcumin was the most sensitive to autoclave treatment. The results indicate that under processing conditions, pH and temperature markedly affect the stability of curcuminoids and major losses of curcuminoids occur after autoclaving. These conditions should be considered when processing foods containing curcuminoids.