• Preventive Nutrition and Food Science
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• v.3 no.1
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• pp.27-35
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• 1998

Starch-polyethylene films containing high molecular weight(NW) oxidized-polyethylene and prooxidant were prepared , and thermal -and bio-degradability of the films were determined. Increased levels of starch resulted in a corresponding reduction in mechanical strength of the films. However, the addition of high MW oxidized-polyethylene did not significantly reduce the percent elongation of the films. Thefilms containing high MW oxidized-polyethylene andproosicant were degreaded faster than those containing no aadditive during the heat treatment. The films lost their measureable mechanical properties when their weight-average MW(Mw) fell below 50,000. Biodegradability of the films was determined by a pure culture assay with either Streptomyces badius 252.S. setonii 75Vi2 or S. viridosporous T7A, and by an extracellulr enzyme assay using S. setonii 75vi2. The results from pure culture assay indicated that biomass accumulation on the film surface inhibited chemical and biological degradation of the films. The extracellular enzyme assay demonstrated decrease of percent elongation and increase of carbonyl index of the films. Therefore, extracellular enzyme assay could be used as a good method to evaluate biodegradability of the films.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.936-942
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• 2012

This review was to elucidate the fate of Bentazon(3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide) and its metabolites in soil. Bentazon is rapidly degraded to form polar metabolites which are mostly adsorbed to soil components, such as humin or fulvic acid, as non extractable forms and mineralized into $CO_2$ by light or micro-organisms in both aerobic or nonaerobic condition. The degradation of Bentazon is dependent on the rate of organic matters in soil and the use of land for the tillage. The degradation rate is decreased as the amount of organic matters in soil increases and if the land is under use for tillage. Sorption and mobility of Bentazon depends on soil pH and the content of organic matters in soil. Usually, the sorption of the metabolites of Bentazon is decreased with increase in the mobility and pH. Almost all of Bentazon is degraded within rhizosphere or forms conjugate bonds with soil organic matters before it reaches to the ground water.

• BMB Reports
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• v.48 no.9
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• pp.525-530
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• 2015

Activation of the Wnt/β-catenin pathway plays a pathogenic role in age-related macular degeneration (AMD) and is thus a potential target for the development of therapeutics for this disease. Here, we demonstrated that Wnt5a antagonized β-catenin response transcription (CRT) induced with Wnt3a by promoting β-catenin phosphorylation at Ser33/Ser37/Thr41 and its subsequent degradation in human retinal pigment epithelial (RPE) cells. Wnt5a decreased the levels of vascular endothelial growth factor (VEGF), tumor necrosis factor-α(TNF-α), and nuclear factor-κB (NF-κB), which was up-regulated by Wnt3a. Furthermore, Wnt5a increased E-cadherin expression and decreased cell migration by down-regulating Snail expression, thereby abrogating the Wnt3a-induced epithelial-mesenchymal transition (EMT) in human RPE cells. Our findings suggest that Wnt5a suppresses the pathogenic effects of canonical Wnt signaling in human RPE cells by promoting β-catenin phosphorylation and degradation. Therefore, Wnt5a has significant therapeutic potential for the treatment of AMD. [BMB Reports 2015; 48(9): 525-530]

• Journal of Microbiology and Biotechnology
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• v.16 no.4
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• pp.590-596
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• 2006

Clavulanic acid (CA) produced by Streptomyces clavuligerus is degraded during the bacterial cultivation. The degradation was examined in three different aspects, including physical, chemical, and enzymatic effects, in order to understand the degradation during the cultivation. The result showed that CA was unstable in the production medium containing ammonium salts and amino acids, owing to ammonium ions and amine groups. In addition, the degradation was not only due to instability of CA by metabolites and proteins, but also enzymes from S. clavuligerus such as $\beta-lactamase$ and penicillin-binding proteins. However, the degradation caused by these enzymes was not highly significant compared with the degradation during the cultivation, owing to irreversible reactions between CA and enzymes.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.6
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• pp.73-83
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• 2015

The objective of this study is to establish implications for forest restoration planning in North Korea by analyzing spatio-temporal forest changes and detecting bio-physical factors driving forest degraded. We measured the relationship and spatial distribution between shifting cultivation and sparse forest. We also analyzed between degraded forest land and ecological variables by binary logistic regression to find biophysical drivers of forest degradation and deforestation in North Korea. Between the sparse forest and the shifting cultivation, a positive relationship is found (r=0.91) and scattered discontinuously throughout the country (Moran's I = -1, Z score = -13.46 (p=0.000)). The sparse forest showed a negative relationship with the warmest month(bio 9), the coldest month(bio10), and the minimum of soil water contents (swc_min), while the shifting cultivation had a negative relationship with the warmest month(bio 9) and the minimum of soil water contents(swc_min). However, the most critical drivers convert forests into sloping farmland were the three months rainfall in summer(bio8) and the yearly mean of soil water contents. Such results reflect the growth period of crops which overlaps with the rainy season in North Korea and the recent land reclamation of uplands where the soil water contents are maintained with a dense forest. When South Korea aids forest restoration projects in North Korea, in consideration of food shortage due to North Korea's cropland deficiency, terrace farmlands where soil water contents can be maintained should be excluded from the priority restoration area. In addition, an evaluation method for selecting a potential restoration area must be modified and applied based on multiple criteria including altitude and socio-economic factors in the respective regions.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.4
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• pp.275-284
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• 2017

The food situation in North Korea (Democratic People's Republic of Korea, DPRK) has been in difficulty situation because of a shortage of energy, and of raw materials such as fertilizer and agricultural chemicals. The international agricultural aid programs can alleviate some difficulties in the agricultural areas, but the policies and measures in North Korea can not help difficulties in the agriculture due to the institutional obstacles enforced by DPRK. The arable area of DPRK is approximately $20,000km^2$, of which $14,000km^2$ is well for cereal cultivation. Fertilizer supplies in recent years between 700,000 and 750,000 tons annually were less than 50% of the normal requirement. Also, North Korea strongly needed to inject phosphorus fertilizer and lime to increase the fertility. Soil degradation in DPRK was characterized by physical and chemical changes caused by rapid loss of clay particles and organic matter. Intensive ploughing and tilling to grow crops may lead to massive soil degradation and declining yields. Although farmers in the DPRK have faced numerous challenges, not least of which are soil erosion, scarce inputs and extreme weather like drought, flooding and cold spells. Therefore farmers should be encouraged to adopt more environmentally sound cropping practices, to access quality seeds and planting materials and to reduce losses after the harvest.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.939-945
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• 2005

The Photocatalytic activity was investigated with the increase of flow rate in a $UV/TiO_2$ packed-bed system. The rate of phenol degradation over $UV/TiO_2$ (dia. = 5 mm) was increased up to 300 mL/min and reached a plateau beyond 400 mL/min. The bead photocatalysts did not exhibit a distinct difference of the phenol degradation rate irrespective of corrosion rates of glass beads and $TiO_2$ coating amounts. Degussa P25 exhibited a higher photocatalytic activity in comparison to other $TiO_2$ sols(Ishihara & N). The performance(activity and durability) of $UV/TiO_2$ packed-bed system can be enhanced by the use of $TiO_2$-coated glass beads instead of granular types that is easily attrited by the shearing force of flowing fluids.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.591-597
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• 2023

Pakistan depends heavily on imports for its fuel requirements. In this experiment, catalytic pyrolysis of a blend of feedstock's consisting of date seed, wheat straw, and corn cob was conducted in a fixed bed reactor to produce oil that can be used as an alternative fuel. The main focus was to emphasize the outcome of important variables on the produced oil. The effects of operating conditions on the yield of bio-oil were studied by changing temperature (350-500 ℃), heating rate (10, 15, 20 ℃/min), and particle size (1, 2, 3 mm). Moreover, ZnO was used as a catalyst in the process. First, the thermal degradation of the feedstock was investigated by TGA and DTG analysis at 10 ℃/min of different particle sizes of 1, 2, and 3mm from a temperature range of 0 to 1000 ℃. The optimum temperature was found to be 450 ℃ for maximum degradation, and the oil yield was indicated to be around 37%. It was deduced from the experiment that the maximum production of bio-oil was 32.21% at a temperature of 450 ℃, a particle size of 1mm, and a heating rate of 15 ℃/min. When using the catalyst under the same operating conditions, the bio-oil production increased to 41.05%. The heating value of the produced oil was 22 MJ/kg compared to low-quality biodiesel oil, which could be used as a fuel.

• Journal of Environmental Science International
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• v.26 no.1
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• pp.1-10
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• 2017

In this study, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/graphene oxide (GO) nanocomposite films containing various content of GO were prepared using solution casting method. The effect of GO content on Young's modulus and dispersion of GO in PHBV matrix was investigated. Also, the thermomechanical properties, oxygen transmission rates and hydrolytic degradation of PHBV/GO nanocomposite films were studied. The addition of GO into PHBV improves the Young's modulus and decreases thermal expansion coefficient. The improvement can be mainly attributed to good dispersion of GO and interfacial interactions between PHBV and GO. Furthermore, PHBV/GO nanocomposite films show good oxygen barrier properties. PHBV/GO nanocomposites show lower hydrolytic degradation rates with increasing content of GO.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.2
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• pp.65-73
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• 2018

This study was carried out for 20 days in a bio-drying batch reactor under the blowing conditions of 0.75, 1.00, 1.25, and $1.50L/min{\cdot}kg$ in order to optimize the operating conditions for the bio-drying of food wastes. The decomposition rate of organic matter during the bio-drying operation period was analyzed using modified Gompertz model. The maximum organic degradation (P) was 2.31, 2.52, 2.27 and 1.88 kg at air flow rates of 0.75, 1.00, 1.25 and $1.50L/min{\cdot}kg$, and the maximum organic degradation rate was 0.33, 0.45, 0.28, and 0.18 kg/day at 1.00, 1.25 and $1.50L/min{\cdot}kg$, respectively, showing excellent organic decomposition efficiency at a air flow rate of $1.00L/min{\cdot}kg$. The lag growth phase time (${\lambda}$) of the bio-drying reactor was 2.10, 1.48, 1.15, and 1.06 days at 0.75, 1.00, 1.25 and $1.50L/min{\cdot}kg$, respectively. The water removal rate in the operation of bio-drying reactor of food waste increased with the increase of air flow rate from the early stage of bio-drying to the middle stage, and the highest water removal rate was observed at the air flow rate of $1.00L/min{\cdot}kg$ at the end of bio-drying. The optimum air flow rate condition of bio-drying reactor was $1.00L/min{\cdot}kg$.