Pressurized Solvent Extraction of Genistein and Its β‐Glucoside Conjugates from Soybean Flours and Soy‐Based Foods     

J. M. Downing  O. K. Chung  P. A. Seib  J. D. Hubbard 《Cereal Chemistry》2007,84(1):44-47

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Surface and subsurface losses of N and P from salt-affected rice paddy fields of Saemangeum reclaimed land in South Korea     

Jae Young Cho  Jae Gwon Son  Jin Kyu Choi  Chang Hoon Song  Byung Yeoup Chung 《Paddy and Water Environment》2008,6(2):211-219

The present study was carried out to evaluate nutrient losses that occur during the course of agricultural activity from rice paddy fields of reclaimed tidal flat. For this study, we chose a salt-affected rice paddy field located in the Saemangeum reclaimed tidal area, which is located on the western South Korean coasts. The plot size was 1,000 m² (40 m × 25 m) with three replicates. The soil belonged to the Gwanghwal series, i.e., it was of the coarse silty, mixed, mesic type of Typic Haplaquents (saline alluvial soil). The input quantities of nitrogen and phosphorus (as chemical fertilizer) into the experimental rice paddy field were 200 kg N ha⁻¹ and 51 kg P₂O₅ ha⁻¹ per annum, and the respective input quantities of each due to precipitation were 9.3–12.9 kg N ha⁻¹ and 0.4–0.7 kg P ha⁻¹ per annum. In terms of irrigation water, these input quantities were 4.5–8.2 kg N ha⁻¹ and 0.3–0.9 kg P ha⁻¹ per annum, respectively. Losses of these nutrients due to surface runoff were 22.5–38.1 kg N ha⁻¹ and 0.7–2.2 kg P ha⁻¹ for the year 2003, and 26.8–29.6 kg N ha⁻¹ and 1.6–1.9 kg P ha⁻¹ for the year 2004, respectively. Losses of these nutrients due to subsurface infiltration during the irrigation period were 0.44–0.67 kg N ha⁻¹ and 0.03–0.04 kg P ha⁻¹ for the year 2003, and 0.15–0.16 kg N ha⁻¹ and 0.05–0.06 kg P ha⁻¹ for 2004. When losses of nitrogen and phosphorus were compared to the amount of nutrients supplied by chemical fertilizers, it was found that 11.3–19.1% of nitrogen and 0.5–1.7% of phosphorus were lost via surface runoff, whereas subsurface losses accounted to 0.2–0.8% for nitrogen and only 0.02–0.04% for phosphorus during the 2-year study period.  相似文献   

Integrated nutrient management for environmental-friendly rice production in salt-affected rice paddy fields of Saemangeum reclaimed land of South Korea     

Jae Young Cho  Jae Gwon Son  Chang Hoon Song  Seon Ah Hwang  Young Min Lee  Se Young Jeong  Byung Yeoup Chung 《Paddy and Water Environment》2008,6(3):263-273

This study was conducted in an attempt to determine the proper nitrogen and phosphorus application levels, nitrogen split application ratio, and application method for environmental-friendly rice production in a salt-affected rice paddy field, which was located in the Saemangeum reclaimed tidal belt on the western coast of South Korea, between April 1, 2003 and October 10, 2004. All treatments were replicated three times in a randomized block design (5 m × 4 m plot) with 11 treatments (total 33 plots). We designed three treatments for the evaluation of reasonable application levels of nitrogen and phosphorus fertilizers (A1–A3); five treatments to evaluate the nitrogen split application system (T1–T5); and three treatments to determine the proper application for chemical fertilizer (M1–M3). There was no significant difference of amylose and protein content among the application levels, application methods, and nitrogen split application ratios (P < 0.05). No significant differences in grain yield and yield components of rice were observed among the different application levels, application methods, and nitrogen split application ratios (P < 0.05). In order to save labor in agricultural households, preserve or enhance the grain quality of rice, and reduce nutrient losses, we determined that the optimum application level of nitrogen fertilizer was 140 kg ha⁻¹; the application split ratio of nitrogen fertilizer at four different periods was 40% for basal fertilization, 20% for maximum tilling stage, 30% for the panicle formation stage, and 10% for the booting stage; and the best application methods were deep layer application and whole layer application.  相似文献   

Solvent Retention Capacity Values in Relation to Hard Winter Wheat and Flour Properties and Straight‐Dough Breadmaking Quality     

Z. S. Xiao  S. H. Park  O. K. Chung  M. S. Caley  P. A. Seib 《Cereal Chemistry》2006,83(5):465-471

Solvent retention capacity (SRC) was investigated in assessing the end use quality of hard winter wheat (HWW). The four SRC values of 116 HWW flours were determined using 5% lactic acid, 50% sucrose, 5% sodium carbonate, and distilled water. The SRC values were greatly affected by wheat and flour protein contents, and showed significant linear correlations with 1,000‐kernel weight and single kernel weight, size, and hardness. The 5% lactic acid SRC value showed the highest correlation (r = 0.83, P < 0.0001) with straight‐dough bread volume, followed by 50% sucrose, and least by distilled water. We found that the 5% lactic acid SRC value differentiated the quality of protein relating to loaf volume. When we selected a set of flours that had a narrow range of protein content of 12–13% (n = 37) from the 116 flours, flour protein content was not significantly correlated with loaf volume. The 5% lactic acid SRC value, however, showed a significant correlation (r = 0.84, P < 0.0001) with loaf volume. The 5% lactic acid SRC value was significantly correlated with SDS‐sedimentation volume (r = 0.83, P < 0.0001). The SDS‐sedimentation test showed a similar capability to 5% lactic acid SRC, correlating significantly with loaf volume for flours with similar protein content (r = 0.72, P < 0.0001). Prediction models for loaf volume were derived from a series of wheat and flour quality parameters. The inclusion of 5% lactic acid SRC values in the prediction model improved R² = 0.778 and root mean square error (RMSE) of 57.2 from R² = 0.609 and RMSE = 75.6, respectively, from the prediction model developed with the single kernel characterization system (SKCS) and near‐infrared reflectance (NIR) spectroscopy data. The prediction models were tested with three validation sets with different protein ranges and confirmed that the 5% lactic acid SRC test is valuable in predicting the loaf volume of bread from a HWW flour, especially for flours with similar protein contents.  相似文献   

Effect of Emulsifiers on Textural Properties of Whole Wheat Tortillas During Storage     

Hülya Akdogan  Michael Tilley  Okkyung K. Chung 《Cereal Chemistry》2006,83(6):632-635

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Reductive Dechlorination of Tetrachloroethylene by Green Rusts Modified with Copper     

Jeongyun Choi  Bill Batchelor  Jinwook Chung 《Water, air, and soil pollution》2010,212(1-4):407-417

Reductive dechlorination of tetrachloroethylene (PCE) by green rust modified with copper (GR(Cu)) was investigated using a batch reactor system. Four different forms of GRs (GR-Cl, GR-SO₄, GR-CO₃, and GR-F) were synthesized by partial air oxidation of Fe(OH)₂ and used in reductive dechlorination. The addition of Cu(II) into GRs produced 100-nm particles on the surface of GRs, which were considered to be metallic Cu and transformed a portion of GR to magnetite. Concentration of Fe(II) in the liquid phase increased and concentration of Fe(II) in the solid phase decreased during the modification process and the extent of these changes was dependent on the amount of Cu(II) added. The most reactive of the modified GRs was GR-F(Cu), which reacted with PCE at a rate that was 80 times faster than that of GR-Cl(Cu). The rate of PCE degradation by GR-F(Cu) was strongly dependent on pH with higher rates at higher pH over the range of pH 7.5–11. Increasing concentrations of Cu(II) over the range of 0 to 5 mM increased rate constants. The rate of dechlorination of PCE by GR-F(Cu) showed surface saturation behavior with respect to PCE concentration.  相似文献   

Mercury and Methylmercury in Freshwater Fish and Sediments in South Korea Using Newly Adopted Purge and Trap GC-MS Detection Method     

Jae-Sung Park  Jung-Sub Lee  Gun-Bae Kim  Jun-Seok Cha  Sun Kyoung Shin  Hak-Gu Kang  Eun-Jin Hong  Gi-Taeg Chung  Young-Hee Kim 《Water, air, and soil pollution》2010,207(1-4):391-401

The use of purge and trap gas chromatography–mass spectrometry (GC-MS) technique for the determination of methylmercury in biological and sediment samples was described. The GC-MS detection system was combined with the dithizone extraction method for biological samples and the distillation method for sediment samples to alleviate matrix interference problems. The method was validated by analysis of CRMs such as SRM 966 (human blood), BCR 463 (tuna fish), IAEA 407 (fish), ERM CC580 (estuarine sediment), and IAEA 405 (sediment). The performance of the purge and trap GC-MS method was also tested on field samples of freshwater fish and sediment. The results were compared with those of the GC-ECD and the GC-CVAFS, which were used widely for methylmercury analysis. Additionally, total mercury and methylmercury levels in freshwater fish and sediments from various reservoirs and streams in Korea were measured to understand mercury contamination status in Korean peninsula. Methylmercury concentrations in freshwater fish were found to correlate with body weight, diet habit, and food availability. In sediment, total mercury concentrations correlated with methylmercury concentrations and organic matter such as %C and %S. However, no significant relationships between methylmercury and sediment organic matter have been found.  相似文献   

Low temperature shape recovery effect of polyurethane copolymer grafted with pendant <Emphasis Type="Italic">n</Emphasis>-butyl group     

Yong-Chan Chung  Jae Won Choi  Ha Youn Kim  Byoung Chul Chun 《Fibers and Polymers》2012,13(1):8-15

Effect of the pendant n-butyl group on shape recovery and tensile properties of polyurethane (PU) block copolymer was investigated. The grafted n-butyl group was intended to keep PU chains away and to deter molecular interaction between PU chains by its flexible chains, and thus improve shape recovery at subzero temperature while maintaining high and reproducible tensile properties and shape recovery at ambient temperature. The attachment of n-butyl group did not make any change in the molecular interaction and phase separation of hard and soft segments in PU structure as judged from IR and DSC analysis. Cross-link density and intrinsic viscosity increased with the increase of n-butyl content due to the partial cross-linking by the linking reagent. Shape recovery and shape retention were not diminished after cyclic shape memory tests. Finally, the effect of n-butyl group on low temperature shape recovery was compared with linear ones and the potential application of this finding was discussed.  相似文献   

Characterization of the ion-paired polyurethane copolymers     

Yong-Chan Chung  Duy Khiem Nguyen  Byoung Chul Chun 《Fibers and Polymers》2012,13(9):1214-1218

The polyurethane (PU) copolymer was grafted with either 3-dimethylaminopropanol as a basic pendant group or 4-hydroxylphenylacetic acid as an acidic pendant group. The two types of PU were mixed in solution to form ion-pairing between acidic and basic pendant groups. The structural change after grafting and ion-pairing was followed by acid-base titration, infrared spectra, differential scanning calorimetry, and absolute viscosity. The tensile stress can be raised as much as 70 % by the control of the ion-pairing ratio of acidic and basic PUs. Shape recovery was over 80 % and reproducible for four test cycles. The minor control of tensile properties of PU was possible through the ion-pairing method.  相似文献   

Uncertainty of paddy irrigation requirement estimated from climate change projections in the Geumho river basin, Korea   总被引：1，自引：1，他引：0  

Sang-Ok Chung  Temba Nkomozepi 《Paddy and Water Environment》2012,10(3):175-185

Despite evidence from numerous studies that over-reliance on a single General Circulation Model (GCM) could lead to inappropriate predictions or adaptation responses to climate change, single GCMs are still used in most mesoscale impact assessments. The objective of this article was to analyze the uncertainty associated with the use of multiple GCMs on future climate change impact assessments on the paddy irrigation water requirements in the Geumho river basin, Korea. Climate projections were extracted for 13 GCMs from the Intergovernmental Panel on Climate Change (IPCC) for A2, A1B, and B1 scenarios, downscaled using the change factor method and were then analyzed. The Food and Agricultural Organization CROPWAT model was used to calculate the paddy irrigation water requirements. Reference evapotranspiration and the crop water requirements were predicted to increase in future periods (2030s, 2055s, and 2090s). Rainfall predictions from the different GCMs exhibited high variability. The projected mean (range) of the paddy irrigation water requirement increase was 1.1% (?9 to 15%), 2.4% (?9 to 13%), and 7.9% (?4 to 24%) for the 2030s, 2055s, and 2090s, respectively, compared to the baseline values (1975s). The predicted irrigation water requirements for the future were shown to have a relative standard deviation of up to 7.1%. Regression analysis was performed on the trends of predicted water requirement over time using the coefficient of determination. It was concluded that multiple models should be used where possible to avoid inappropriate planning or adaptation responses particularly in the short term. Adaptation strategies are required to mitigate the future impact of increasing future water demand.  相似文献