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21.
Lee SC Kim JH Jeong SM Kim DR Ha JU Nam KC Ahn DU 《Journal of agricultural and food chemistry》2003,51(15):4400-4403
After far-infrared (FIR) radiation onto rice hull, a methanolic extract was prepared for the determination of antioxidant ability. After 30 min of FIR treatment, the radical scavenging activity and total phenol contents of rice hull extracts increased from 47.74 to 79.63% and from 0.12 to 0.19 mM, respectively, compared to control. Inhibition of lipid peroxidation in extracts was also increased from 41.07 to 47.96%. According to the GC-MS analysis, more phenolic compounds (p-coumaric acid, 3-vinyl-1-oxybenzene, p-hydroxybenzaldehyde, vanillin, p-hydroxybenzoic acid, and 4,7-dihydroxyvanillic acid) were detected in FIR-irradiated rice hull extract. These results indicated that FIR radiation onto rice hull could liberate and activate covalently bound phenolic compounds that have antioxidant activities. 相似文献
22.
This study was conducted to examine whether the applications of N-inputs (compost and fertilizer) having different N isotopic compositions (δ15N) produce isotopically different inorganic-N and to investigate the effect of soil moisture regimes on the temporal variations in the δ15N of inorganic-N in soils. To do so, the temporal variations in the concentrations and the δ15N of NH4+ and NO3− in soils treated with two levels (0 and 150 mg N kg−1) of ammonium sulfate (δ15N=−2.3‰) and compost (+13.9‰) during a 10-week incubation were compared by changing soil moisture regime after 6 weeks either from saturated to unsaturated conditions or vice versa. Another incubation study using 15N-labeled ammonium sulfate (3.05 15N atom%) was conducted to estimate the rates of nitrification and denitrification with a numerical model FLUAZ. The δ15N values of NH4+ and NO3− were greatly affected by the availability of substrate for each of the nitrification and denitrification processes and the soil moisture status that affects the relative predominance between the two processes. Under saturated conditions for 6 weeks, the δ15N of NH4+ in soils treated with fertilizer progressively increased from +2.9‰ at 0.5 week to +18.9‰ at 6 weeks due to nitrification. During the same period, NO3− concentrations were consistently low and the corresponding δ15N increased from +16.3 to +39.2‰ through denitrification. Under subsequent water-unsaturated conditions, the NO3− concentrations increased through nitrification, which resulted in the decrease in the δ15N of NO3−. In soils, which were unsaturated for the first 6-weeks incubation, the δ15N of NH4+ increased sharply at 0.5 week due to fast nitrification. On the other hand, the δ15N of NO3− showed the lowest value at 0.5 week due to incomplete nitrification, but after a subsequence increase, they remained stable while nitrification and denitrification were negligible between 1 and 6 weeks. Changing to saturated conditions after the initial 6-weeks incubation, however, increased the δ15N of NO3− progressively with a concurrent decrease in NO3− concentration through denitrification. The differences in δ15N of NO−3 between compost and fertilizer treatments were consistent throughout the incubation period. The δ15N of NO3− increased with the addition of compost (range: +13.0 to +35.4‰), but decreased with the addition of fertilizer (−10.8 to +11.4‰), thus resulting in intermediate values in soils receiving both fertilizer and compost (−3.5 to +20.3‰). Therefore, such differences in δ15N of NO3− observed in this study suggest a possibility that the δ15N of upland-grown plants receiving compost would be higher than those treated with fertilizer because NO3− is the most abundant N for plant uptake in upland soils. 相似文献
23.
Persistent Organic Pollutants in Singapore's Coastal Marine Environment: Part II,Sediments 总被引:1,自引:0,他引:1
Basheer Chanbasha Obbard Jeffrey Philip Lee Hian Kee 《Water, air, and soil pollution》2003,149(1-4):315-325
Polycyclic aromatic hydrocarbons (PAHs) can enter the marine environment from a variety of anthropogenic sources. As some PAHs are known or suspected carcinogens and mutagens, their potential hazard to human health and the natural environment warrants investigation. This is the first reported study on the prevalence and concentration of PAHs in marine sediments from Singapore's coastal environment, and accompanies the report by Basheer et al. (2003) on the measurement of persistent organic pollutants (POPs) in seawater. The concentration of 16 PAH, classified as USEPA priority pollutants were analysed in sediments from 22 sample stations located within the northeastern and southwestern regions of Singapore's marine waters. The total PAH concentration varied between 15.22 μg g-1 and 82.41 μg g-1 in the northeastern region and between 13.63 μg g-1 and 84.92 μg g-1in the southwestern region. The highest concentration of total PAH i.e. 84.92 μg g-1 was recorded at a site adjacent to a petrochemical refinery. Among the sixteen individual PAHs, chrysene, indeno[1,2,3-cd]pyrene and benzo[a]anthracene were most prevalent in the sediments. The relatively low kinetic/thermodynamic isomer ratios for PAHs suggest that PAHs of pyrogenic origin are predominant in Singapore's coastal environment. The distribution of higher molecular weight i.e. (4–5 ring) individual PAHs corresponded to mixture profiles typical of those originating from high temperature combustion processes subjected to photolytic degradation during long-range atmospheric transportation. A comparison of total PAH concentration data for sediments collected from Singapore relative to those reported for other countries indicates a moderate level of PAH contamination in Singapore's coastal marine sediments. 相似文献
24.
A Laboratory Column Study on the Biodegradation of Toluene and Methyl tert–Butyl Ether: The Effect of Substrate Interactions 总被引:1,自引:0,他引:1
Chung Seung-Gun Kim Dong-Ju Lee Sang-Hyup Choi Jae-Woo 《Water, air, and soil pollution》2013,224(4):1-8
Soil vapor extraction (SVE) is one of the most effective remediation technologies for soil and groundwater contamination. Soil particles can be mobilized by air perturbation during SVE, resulting in the differentiation of porous media, which has not been well addressed. This paper developed a numerical method to study the flow pattern and quantify the change of porous media for the first time. Based on the mass equilibrium and Darcy’s law, a two-phase water–air flow model was constructed with integration of saturation, relative permeability, and capillary pressure during SVE. Relationship between porosity and saturation was deduced and coupled with the two-phase flow model for quantifying change of porous media in real time. Results reveal that both porosity and permeability increase sharply in the early stage of SVE then gradually to a quasi-steady state. These increases in vadose zone tapered off with distance from the SVE screen and the steady period occurred later as well. The influence radius of a single SVE well and the change degree in porosity and permeability of media were proportional to the extraction vacuum and the driving coefficient C, which is more sensitive than extraction vacuum according to the simulation results. Knowledge from this modeling exercise provides a useful tool to estimate the change of remediated zone and assess the environmental risk of remedial activities at real-world contamination sites. 相似文献
25.
Lee HJ Shan G Ahn KC Park EK Watanabe T Gee SJ Hammock BD 《Journal of agricultural and food chemistry》2004,52(5):1039-1043
A competitive enzyme-linked immunosorbent assay (ELISA) for the detection of cypermethrin was developed. Two haptens, the trans- and cis-isomers of 3-[(+/-)-cyano-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarbonyloxy]methyl]phenoxyacetic acid, were conjugated with thyroglobulin as immunogens. Four antisera were generated and screened against six different coating antigens. The assay that was the most sensitive for cypermethrin was optimized and characterized. The IC(50) for cypermethrin was 13.5 +/- 4.3 microg/L, and the lower detection limit (LDL) was 1.3 +/- 0.5 microg/L. This ELISA had relatively low cross-reactivities with other major pyrethroids, such as deltamethrin, phenothrin, resmethrin, fluvalinate, and permethrin. Methanol was found to be the best organic cosolvent for this ELISA, with an optimal sensitivity observed at a concentration of 40% (v/v). The assay parameters were unchanged at pH values between 5.0 and 8.0, whereas higher ionic strengths strongly suppressed the absorbances. To increase the sensitivity of the overall method, a C(18) sorbent-based solid-phase extraction was applied to various domestic and environmental water samples. The water samples, fortified with cypermethrin, were analyzed according to this method. Good recoveries and correlation with spike levels were observed. 相似文献
26.
Determination of antioxidant potential of volatile extracts isolated from various herbs and spices 总被引:10,自引:0,他引:10
Antioxidant activities of volatile extracts isolated from thyme, basil, rosemary, chamomile, lavender, and cinnamon were evaluated by two independent assays: the aldehyde/carboxylic acid assay and the conjugated diene assay. The volatile extracts were prepared from dried herbs and spices using liquid-liquid continuous extraction following steam distillation under reduced pressure (55 degrees C and 95 mmHg). The antioxidant activities of the extracts decreased in the following order in both of the lipophilic assay systems: thyme > basil > rosemary > chamomile > lavender and cinnamon. Thyme and basil extracts inhibited the oxidation of hexanal for 40 days at the levels of 10 microg/mL and 50 microg/mL, respectively. The extracts of thyme and basil were effective in retarding methyl linoleate deterioration at 40 degrees C, with activity increasing with concentration in the range 10-200 microg/mL. At a concentration of 50 microg/mL, thyme extract was similar in antioxidant activity to BHT and alpha-tocopherol in the conjugated diene assay. The antioxidant potentials of the volatile extracts used in this study were accurately measured by the lipophilic systems, such as the aldehyde/carboxylic acid assay and the conjugated diene assay. 相似文献
27.
28.
B.C. Lee Y.K. He K. Murao M. Isogai G. Dahal I. Uyeda 《European journal of plant pathology / European Foundation for Plant Pathology》1997,103(6):493-499
Rice dwarf virus isolates were collected from several locations in Japan, the Philippines, China, Nepal and Korea. Genomic dsRNA segment profiles in polyacrylamide gel electrophoresis differed among the isolates. There were less differences in the profiles between isolates from Japan and Korea than in those between these two Countries and others. Nucleic acid hybridization was used to examine the extent of genomic variation. Full-length cDNAs to all genomic segments encoding non-structural proteins (S4, S6, S9, S10, S11 and S12) were synthesized from two Japanese isolates, and were used for dot-blot hybridization. Hybridizations using probes generated from the full-length cDNA clones failed to differentiate isolates from different geographical areas. However, cDNA probes covering a variable region of S12 were able to distinguish Japanese and Korean isolates from those of other countries. Phylogenetic tree analysis based on the amino acid sequence of P12 encoded by S12 grouped Japanese and Korean isolates together. The Chinese isolates from two different locations (Yunnan and Fujian) were closely related to each other, and were the most distantly related to Japanese and Korean isolates. 相似文献
29.
Lee IT Levy JK Gorman SP Crawford PC Slater MR 《Journal of the American Veterinary Medical Association》2002,220(5):620-622
OBJECTIVE: To determine prevalence of FeLV infection and serum antibodies against feline immunodeficiency virus (FIV) in unowned free-roaming cats. DESIGN: Cross-sectional serologic survey. ANIMALS: 733 unowned free-roaming cats in Raleigh, NC, and 1,143 unowned free-roaming cats in Gainesville, Fla. RESULTS: In Raleigh, overall prevalence of FeLV infection was 5.3%, and overall seroprevalence for FIV was 2.3%. In Gainesville, overall prevalence of FeLV infection was 3.7%, and overall seroprevalence for FIV was 4.3%. Overall, FeLV prevalence was 4.3%, and seroprevalence for FIV was 3.5%. Prevalence of FeLV infection was not significantly different between males (4.9%) and females (3.8%), although seroprevalence for FIV was significantly higher in male cats (6.3%) than in female cats (1.5%). CONCLUSIONS AND CLINICAL RELEVANCE: Prevalence of FeLV infection and seroprevalence for FIV in unowned free-roaming cats in Raleigh and Gainesville are similar to prevalence rates reported for owned cats in the United States. Male cats are at increased risk for exposure to FIV, compared with female cats. 相似文献
30.
Hye Kwon Kim Jeong Sun Yang Hyoung Joon Moon Seong Jun Park Yuzi Luo Chul Seung Lee Dae Sub Song Bo Kyu Kang Soo Kyung Ann Chan Hyuk Jun Bong Kyun Park 《Journal of veterinary science (Suw?n-si, Korea)》2009,10(2):121-130
The 23 open reading frame (ORF) 5 sequences of Korean type II porcine reproductive and respiratory syndrome virus (PRRSV) were collected from viremic sera from the (modified live vaccine) MLV-vaccinating and non-vaccinating farms from 2007 to 2008. The samples were phylogenetically analyzed with previous ORF5 sequences, including type I Korean PRRSV, and previously reported or collected sequences from 1997 to 2008. A MN184-like subgroup of type II Korean PRRSV was newly identified in the viremic sera collected from 2007 to 2008. And of the type I PRRSVs, one subgroup had 87.2~88.9% similarity with the Lelystad virus, showing a close relationship with the 27~2003 strain of Spain. The maximum parsimony tree of type II PRRSV from 1997 to 2008 showed that they had evolved to four lineages, subgroups 1, 2, 3 and 4. Most of the recently collected type II PRRSVs belonged to subgroup 4 (48%). The region of three B-cell epitopes and two T-cell epitopes of ORF5 amino acids sequences was considerably different from the MLV in subgroups 3 and 4. In conclusion, the existence of type I PRRSV, which was genetically different from Lelystad virus (Prototype of type I PRRSV), and heterologous type II PRRSVs of viremic pigs detected even in the MLV-vaccinating farms indicated the need for new vaccine approaches for the control of PRRSV in Korea. 相似文献