• The Korean Journal of Food And Nutrition
• /
• v.32 no.4
• /
• pp.379-384
• /
• 2019

This study was to investigate the sorbic acid, benzoic acid and sulfur dioxide in commonly consumed beverages, snacks and instant ramens in Korea. A total of 150 food samples including 50 beverages, 50 snacks and 50 instant ramens were examined using the Korea Food Code method. Sorbic and benzoic acid were analyzed by the HPLC method, whereas sulfur dioxide was measured by Monnier-Williams method. Our results indicated that benzoic acid was detected in six beverages samples, and its concentration was in the range of 3.08-11.94 mg/kg. The contents of both sorbic and benzoic acid in 50 beverage samples did not exceed the residue allowance standards set by the Ministry of Food and Drug Safety (MFDS). Sulfur dioxide was detected in 12 beverages samples, but its content was lower than the detection limit specified in the method by the Korea Food Code. On the other hand, sorbic acid was not detected all samples. These results provide a basic data regarding sorbic acid, benzoic acid and sulfur dioxide in commonly consumed beverages, snacks and instant ramens in Korea.

• Microbiology and Biotechnology Letters
• /
• v.49 no.1
• /
• pp.120-129
• /
• 2021

Rotavirus A (RVA) is recognized as a major etiology responsible for the development of acute gastroenteritis in children worldwide. The purpose of the present study was to perform the molecular characterization of RVA. A total of 323 stool specimens collected from hospitalized children with acute gastroenteritis in Chiang Rai, Thailand, in 2016-2018 were identified for G- and P-genotypes through RT-PCR analysis. RVA was more prevalent in 2017-2018 (37.8%) than in 2016-2017 (23.2%). The seasonal peak of RVA occurred from March to April. G3P[8] was predominant in 2016-2017 (90.6%) and 2017-2018 (58.6%). Other genotypes including G1P[8], G8P[8], G9P[8], and mixed infections were also identified. G3P[8] strains clustered together in the same lineage with other novel human equine-like G3P[8] strains previously identified in multiple countries and presented a genotype 2 constellation (G3-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2). Several amino acid differences were observed in the antigenic epitopes of the VP7 and VP8* capsid proteins of the equine-like G3P[8] compared with those of the RVA vaccine strains. The homology modeling of the VP7 and VP8* capsid proteins of the equine-like G3P[8] strains evidently exhibited that these residue differences were present on the surface-exposed area of the capsid structure. The emergence of the equine-like G3P[8] strains in Thailand indicates the rapid spread of strains with human and animal gene segments. Continuous surveillance for RVA is essential to monitor genotypes and genetic diversity, which will provide useful information for selecting rotavirus strains to develop a safe and effective RVA vaccine that is efficacious against multiple genotypes and variants.

• Journal of Microbiology and Biotechnology
• /
• v.32 no.3
• /
• pp.287-293
• /
• 2022

The hydroxylation of methane (CH₄) is crucial to the field of environmental microbiology, owing to the heat capacity of methane, which is much higher than that of carbon dioxide (CO₂). Soluble methane monooxygenase (sMMO), a member of the bacterial multicomponent monooxygenase (BMM) superfamily, is essential for the hydroxylation of specific substrates, including hydroxylase (MMOH), regulatory component (MMOB), and reductase (MMOR). The diiron active site positioned in the MMOH α-subunit is reduced through the interaction of MMOR in the catalytic cycle. The electron transfer pathway, however, is not yet fully understood due to the absence of complex structures with reductases. A type II methanotroph, Methylosinus sporium 5, successfully expressed sMMO and hydroxylase, which were purified for the study of the mechanisms. Studies on the MMOH-MMOB interaction have demonstrated that Tyr76 and Trp78 induce hydrophobic interactions through π-π stacking. Structural analysis and sequencing of the ferredoxin domain in MMOR (MMOR-Fd) suggested that Tyr93 and Tyr95 could be key residues for electron transfer. Mutational studies of these residues have shown that the concentrations of flavin adenine dinucleotide (FAD) and iron ions are changed. The measurements of dissociation constants (K_ds) between hydroxylase and mutated reductases confirmed that the binding affinities were not significantly changed, although the specific enzyme activities were significantly reduced by MMOR-Y93A. This result shows that Tyr93 could be a crucial residue for the electron transfer route at the interface between hydroxylase and reductase.

• Korean Journal of Agricultural Science
• /
• v.49 no.2
• /
• pp.317-330
• /
• 2022

Recently, the policy regarding climate change in Korea and overseas has been to promote the utilization of forest biomass to achieve net zero emissions. In addition, with the implementation of the unused forest biomass system in 2018, the size of the Korean market for manufacturing wood pellets and wood chips using unused forest biomass is rapidly expanding. Therefore, it is necessary to estimate the total amount of unused forest biomass that can be used as an energy source and to identify the capacity that can be continuously produced annually. In this study, we estimated the actual forest area that can be produced of logging residue and the potential amount of unused forest biomass resources based on GT (green ton). Using a forest functions classification map (1 : 25,000), 5th digital forest type map (1 : 25,000), and digital elevation model (DEM), the forest area with a slope of 30° or less and mountain ridges of 70% or less was estimated based on production forest and IV age class or more. The total forest area where unused forest biomass can be produced was estimated to be 1,453,047 ha. Based on GT, the total amount of unused forest biomass potential resources in Korea was estimated to be 117,741,436 tons. By forest type, coniferous forests were estimated to be 48,513,580 tons (41.2%), broad-leaved forests 27,419,391 tons (23.3%), and mixed forests 41,808,465 tons (35.5%). Data from this research analysis can be used as basic data to estimate commercial use of unused forest biomass.

• Molecules and Cells
• /
• v.46 no.8
• /
• pp.513-525
• /
• 2023

Orange carotenoid protein (OCP) of photosynthetic cyanobacteria binds to ketocarotenoids noncovalently and absorbs excess light to protect the host organism from light-induced oxidative damage. Herein, we found that mutating valine 40 in the α3 helix of Gloeocapsa sp. PCC 7513 (GlOCP1) resulted in blue- or red-shifts of 6-20 nm in the absorption maxima of the lit forms. We analyzed the origins of absorption maxima shifts by integrating X-ray crystallography, homology modeling, molecular dynamics simulations, and hybrid quantum mechanics/molecular mechanics calculations. Our analysis suggested that the single residue mutations alter the polar environment surrounding the bound canthaxanthin, thereby modulating the degree of charge transfer in the photoexcited state of the chromophore. Our integrated investigations reveal the mechanism of color adaptation specific to OCPs and suggest a design principle for color-specific photoswitches.

• Korean Journal of Environmental Agriculture
• /
• v.42 no.3
• /
• pp.220-230
• /
• 2023

Imidacloprid is a neonicotinoid insecticide widely used for insect control in a variety of crops. The evaluation of imidacloprid total residues in animal feeds derived from crop by-products is required to ensure the safety of livestock products. We performed simultaneous LC/MS/MS analyses of imidacloprid and its metabolites in five different livestock products including beef, pork, chicken, milk and egg from domestic markets. The methods for sample preparation and instrumental analysis were established by modifying QuEChERS method to meet the Codex guidelines. The methods generated 0.0035 mg/kg of the limit of determination (LOD), 0.01 mg/kg of the limit of quantitation (LOQ) and standard calibration linearity with >0.983 of the coefficients of determination (R²). The methods exhibited the recovery values of imidacloprid and its metabolites ranging from 65.66 to 119.27% without any interference between matrices. Imidacloprid total residues in the livestock products were found as values lower than the LOQ and maximum residue limits (MRLs). This study suggests that the methods are successfully applicable for the safety evaluation of imidacloprid total residues in livestock products from domestic markets.

• Korean Journal of Environmental Agriculture
• /
• v.42 no.2
• /
• pp.131-138
• /
• 2023

The biological half-life and dissipation rate of azoxystrobin in crown daisy were calculated to establish the pre-harvest residue limits (PHRLs). The pesticide residues were calculated after washing with five different processes to propose an effective process in the household and conducted a risk assessment to confirm dietary safety. Azoxystrobin was sprayed according to the critical good agricultural practices (cGAP) in two different field trials, and the samples were harvested 7 times. The limit of quantitation was 0.02 mg/kg, and the mean recoveries of azoxystrobin were within the range of 70~120% with below 20% coefficient variation at the concentration of 0.02 and 0.2 mg/kg . The biological half-lives were 7.4 and 4.7 days, and the dissipation rate constants were 0.0872 and 0.1217 in fields 1 and 2, respectively. The average removal rates were 58.13~78.13% by the different washing processes, and there were significant differences between the washing processes (one-way ANOVA analysis and post-hoc Duncan test, p-value<0.05). The residues of azoxystrobin in crown daisy were safe levels from farm to fork after application with the critical good agricultural practice (cGAP) registered in Korea.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.05a
• /
• pp.91-92
• /
• 2023

With the development of technology, interest in the implementation of free-form buildings is increasing, and research on producing free-form panels is being conducted accordingly. Since free-form buildings are curved and consist of geometric shapes, there are many problems with the production technology of free-form panels that implement them. Due to the inability to reuse molds, the cost of disposal of construction waste and waste of manpower for assembly increase the construction period and construction cost. To improve these limitations, a 3D printed concrete nozzle for FCP production was developed. However, this technology is not quantitatively extruded according to the shape of the panel, and there is a problem that residues are generated. Therefore, an free-form panel extrusion experiment was conducted to analyze the limitations of existing nozzles and to analyze the requirements for the development of new concrete extrusion nozzles. Existing nozzles were unable to be quantitatively extruded, resulting in errors. Due to the weak pressure of the screw and the inability to adjust the internal pressure, detailed extrusion speed control was impossible, and residue generation in the opening and closing device seemed to be the cause. Therefore, a pump capable of quantitative concrete pressure transfer and a pressure control device for easy extrusion of concrete are required. In addition, it is judged that it is necessary to develop an opening and closing device and an extrusion device that do not generate residues. The results of this study are expected to provide information for FCP production and production and to be a basic study of technologies necessary for the production of free-form building panels.

• Korean Journal of Veterinary Research
• /
• v.63 no.3
• /
• pp.23.1-23.9
• /
• 2023

This study was conducted to investigate tiamulin (TML) residues in the edible tissues of orally dosed broiler chickens and to re-establish the withdrawal time (WT). Thirty-six healthy Ross broiler chickens were administered 0.5 (TML-1) and 2.5 kg (TML-2) per ton feed, respectively, of the drug containing TML 78 g/kg for 10 days. Twenty-four tissue samples were collected from 6 chickens in each of the TML-1 and TML-2 groups on 0, 1, 3, and 5 days after drug administration, respectively. The residual concentrations of TML were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The correlation coefficient of the calibration curves was 0.9978 to 0.9998, and the limits of detection and the limits of quantification (LOQ) were in the range of 0.03 to 0.06, and 0.1 to 0.2 ㎍/kg, respectively. Recoveries ranged between 89.0% to 116.7%, and the coefficients of variation were less than 13.9%. After the drug administration, TML in the TML-1 and TML-2 groups was detected above the LOQ in 1 and 6 samples of liver, respectively, at day 0, and in 1 liver sample from both groups on day one. At 3 days after administration, TML was detected below the LOQ in all samples of TML-1 and TML-2. The calculated WT of TML in both TML-1 and TML-2 using the WT calculation program WT 1.4 was 0 days. In conclusion, the developed analytical method is suitable for detection, and the calculated WT of TML in poultry edible tissues is shorter than the current recommended WT of 7 days for TML in broiler chickens.

• Korean Journal of Agricultural Science
• /
• v.50 no.4
• /
• pp.713-721
• /
• 2023

Soil acidification challenges global food security by adversely influences soil fertility and agricultural productivity. Carbonized agricultural residues present a sustainable and ecofriendly way to recycle agricultural waste and mitigate soil acidification. We evaluated the effects of organic amendments on lettuce growth and soil chemical properties in two soils with different pH levels. Carbonized rice husk was produced at 600℃ for 30 min and rice husk was treated at 1% (w·w^-1). Carbonized rice husk increased soil pH, electrical conductivity, total carbon content, and nitrogen content compared with untreated and rice husk treatments. Furthermore, this study found that lettuce growth positively correlated with soil pH, with increasing soil pH up to pH 6.34 resulting in improved lettuce growth parameters. Statistical correlation analysis also supported the relationship between soil pH and lettuce growth parameters. The study findings showed that the use of carbonized rice husk increased the constituent elements of lettuce, such as carbon, nitrogen, and phosphate content. The potassium content of lettuce followed a similar trend; however, was higher in acidic soil than that in non-acidic soil. Therefore, improving the pH of acidic soil is essential to enhance agricultural productivity. It is considered advantageous to use agricultural residues following pyrolysis to improve soil pH and agricultural productivity.