Evaluation of Disposal Stability for Cement Solidification of Lime Waste.

The Korea Atomic Energy Research Institute (KAERI) obtains UO2 powder using the ammonium uranyl carbonate (AUC) wet process. Hydrated lime (Ca(OH)2) is used to neutralize liquid wastes produced from the AUC process, and the resulting byproduct is known as lime waste. The purpose of this study is to determine optimum operating conditions for cementation of radioactive lime waste produced from the AUC process, and to evaluate the structural stability and leaching stability of cement waste form. The waste acceptance criteria (WAC) of a waste disposal facility in Korea were used to evaluate the cement waste form samples. The maximum lime waste content guaranteeing the shape stability of cement waste form was found to be 80 wt.% or less. Considering the economic feasibility and error of the cementation process, the optimum operating conditions were achieved at a lime waste content of 75 wt.% and a water-to-cement (w/c) ratio of 2.0. The compressive strength of cement waste form samples prepared under optimal operating conditions was 61.4, 76.3, and 61.0 kgf/cm2 after the thermal cycling test, water immersion test, and irradiation, respectively, satisfying the compressive strength of 35.2 kgf/cm2 specified in WAC. A leaching test was performed on the samples, and the leachability indexes (LX) of Cs, Sr, and Co nuclides were 7.63, 8.02, and 10.89, respectively, which are all higher than the acceptance criterion of 6. The results showed that the cement waste forms prepared under optimal operating conditions satisfied the WAC in terms of structural stability and leaching stability. As such, the proposed cement solidification method for lime waste disposal can be effective in solidifying lime waste powder produced during the neutralization of liquid wastes in the AUC process.

Versatile Poly(Diallyl Dimethyl Ammonium Chloride)-Layered Nanocomposites for Removal of Cesium in Water Purification.

In this work, we elucidate polymer-layered hollow Prussian blue-coated magnetic nanocomposites as an adsorbent to remove radioactive cesium from environmentally contaminated water. To do this, Fe3O4 nanoparticles prepared using a coprecipitation method were thickly covered with a layer of cationic polymer to attach hollow Prussian blue through a self-assembly process. The as-synthesized adsorbent was confirmed through various analytical techniques. The adsorbent showed a high surface area (166.16 m²/g) with an excellent cesium adsorbent capacity and removal efficiency of 32.8 mg/g and 99.69%, respectively. Moreover, the superparamagnetism allows effective recovery of the adsorbent using an external magnetic field after the adsorption process. Therefore, the magnetic adsorbent with a high adsorption efficiency and convenient recovery is expected to be effectively used for rapid remediation of radioactive contamination.

Simple Analysis of Lipid Inhibition Activity on an Adipocyte Micro-Cell Pattern Chip.

Polydimethyl-siloxane (PDMS) is often applied to fabricate cell chips. In this study, we fabricated an adipocyte microcell pattern chips using PDMS to analyze the inhibition activity of lipid droplets in mouse embryo fibroblast cells (3T3-L1) with anti-obesity agents. To form the PDMS based micropattern, we applied the micro-contact printing technique using PDMS micro-stamps that had been fabricated by conventional soft lithography. This PDMS micro-pattern enabled the selective growth of 3T3-L1 cells onto the specific region by preventing cell adhesion on the PDMS region. It then allowed growth of the 3T3-L1 cells in the chip for 10 days and confirmed that lipid droplets were formed in the 3T3-L1 cells. After treatment of orlistat and quercetin were treated in an adipocyte micro-cell pattern chip with 3T3-L1 cells for six days, we found that orlistat and quercetin exhibited fat inhibition capacities of 19.3% and 24.4% from 0.2 µM of lipid droplets in 3T3-L1 cells. In addition, we conducted a direct quantitative analysis of 3T3-L1 cell differentiation using Oil Red O staining. In conclusion, PDMS-based adipocyte micro-cell pattern chips may contribute to the development of novel bioactive compounds.

Characterization of Nivalenol-Producing Fusarium culmorum Isolates Obtained from the Air at a Rice Paddy Field in Korea.

Together with the Fusarium graminearum species complex, F. culmorum is a major member of the causal agents of Fusarium head blight on cereals such as wheat, barley and corn. It causes significant yield and quality losses and results in the contamination of grain with mycotoxins that are harmful to humans and animals. In Korea, F. culmorum is listed as a quarantine fungal species since it has yet to be found in the country. In this paper, we report that two isolates (J1 and J2) of F. culmorum were collected from the air at a rice paddy field in Korea. Species identification was confirmed by phylogenetic analysis using multi-locus sequence data derived from five genes encoding translation elongation factor, histone H3, phosphate permease, a reductase, and an ammonia ligase and by morphological comparison with reference strains. Both diagnostic PCR and chemical analysis confirmed that these F. culmorum isolates had the capacity to produce nivalenol, the trichothecene mycotoxin, in rice substrate. In addition, both isolates were pathogenic on wheat heads and corn stalks. This is the first report on the occurrence of F. culmorum in Korea.

A Rapid In Situ Colorimetric Assay for Cobalt Detection by the Naked Eye.

A simple, rapid, and convenient colorimetric chemosensor of a specific target toward the end user is still required for on-site detection and real-time monitoring applications. In this study, we developed a rapid in situ colorimetric assay for cobalt detection using the naked eye. Interestingly, a yellow to light orange visual color transition was observed within 3 s when a Chrysoidine G (CG) chemosensor was exposed to cobalt. Surprisingly, the CG chemosensor had great selectivity toward cobalt without any interference of other metal ions. Under optimized conditions, a lower detection limit of 0.1 ppm via a spectrophotometer and a visual detection limit of 2 ppm with a linear range from 0.4 to 1 ppm (R² = 0.97) were determined. Moreover, the CG chemosensor is reversible and maintains its functionality after treatment with chelating agents. In conclusion, we show the superior capabilities of the CG chemosensor, which has the potential to provide extremely facile handling, high sensitivity, and a fast response time for applications of on-site detection to real-time cobalt monitoring for the general public.

A Large-Scale Functional Analysis of Putative Target Genes of Mating-Type Loci Provides Insight into the Regulation of Sexual Development of the Cereal Pathogen Fusarium graminearum.

Fusarium graminearum, the causal agent of Fusarium head blight in cereal crops, produces sexual progeny (ascospore) as an important overwintering and dissemination strategy for completing the disease cycle. This homothallic ascomycetous species does not require a partner for sexual mating; instead, it carries two opposite mating-type (MAT) loci in a single nucleus to control sexual development. To gain a comprehensive understanding of the regulation of sexual development in F. graminearum, we used in-depth and high-throughput analyses to examine the target genes controlled transcriptionally by two-linked MAT loci (MAT1-1, MAT1-2). We hybridized a genome-wide microarray with total RNAs from F. graminearum mutants that lacked each MAT locus individually or together, and overexpressed MAT1-2-1, as well as their wild-type progenitor, at an early stage of sexual development. A comparison of the gene expression levels revealed a total of 1,245 differentially expressed genes (DEGs) among all of the mutants examined. Among these, genes involved in metabolism, cell wall organization, cellular response to stimuli, cell adhesion, fertilization, development, chromatin silencing, and signal transduction, were significantly enriched. Protein binding microarray analysis revealed the presence of putative core DNA binding sequences (ATTAAT or ATTGTT) for the HMG (high mobility group)-box motif in the MAT1-2-1 protein. Targeted deletion of 106 DEGs revealed 25 genes that were specifically required for sexual development, most of which were regulated transcriptionally by both the MAT1-1 and MAT1-2 loci. Taken together with the expression patterns of key target genes, we propose a regulatory pathway for MAT-mediated sexual development, in which both MAT loci may be activated by several environmental cues via chromatin remodeling and/or signaling pathways, and then control the expression of at least 1,245 target genes during sexual development via regulatory cascades and/or networks involving several downstream transcription factors and a putative RNA interference pathway.

Inhibitory effects of Asterina pectinifera extracts on melanin biosynthesis through tyrosinase activity.

The control of melanogenesis is an important strategy in the treatment of abnormal skin pigmentation for cosmetic purposes. The aim of the present study was to investigate the anti-melanogenic effect of Asterina pectinifera (A. pectinifera) extracts by cell-free mushroom tyrosinase assay, cellular tyrosinase assay, melanin content assay and the analysis of related protein expression in melan-a cells. A. pectinifera was extracted with 80% methanol (80-MAP) and further fractionated with hexane (He-AP) and ethyl acetate (EA-AP). In addition, the enzyme extract (En-AP) of A. pectinifera, to which protease was added, was processed. EA-AP and En-AP among A. pectinifera extracts showed strong inhibitory activity against the cell-free mushroom tyrosinase activity. EA-AP and En-AP induced significant inhibition of melanin production and cellular tyrosinase activity. In the action of EA-AP and En-AP on melanogenesis, they reduced the expression of melanogenic genes and proteins including tyrosinase, tyrosinase-related protein-1 (TRP-1) and dopachrome tautomerase (Dct). These results showed that EA-AP and En-AP inhibited melanogenesis by reducing tyrosinase activity and melanin production via subsequent downregulation of tyrosinase-related proteins. The overall results suggest that EA-AP and En-AP among A. pectinifera extracts may be promising candidates for the treatment of hyperpigmentation disorder and useful for self-tanning cosmetic products.

Effects of White Radish (Raphanus sativus) Enzyme Extract on Hepatotoxicity.

Raphanus sativus (Cruciferaceae), commonly known as radish is widely available throughout the world. From antiquity it has been used in folk medicine as a natural drug against many toxicants. The present study was designed to evaluate the hepatoprotective activity of radish (Raphanus sativus) enzyme extract (REE) in vitro and in vivo test. The IC50 values of REE in human liver derived HepG2 cells was over 5,000 µg/ml in tested maximum concentration. The effect of REE to protect tacrine-induced cytotoxicity in HepG2 cells was evaluated by MTT assay. REE showed their hepatoprotective activities on tacrineinduced cytotoxicity and the EC50 value was 1,250 µg/ml. Silymarin, an antihepatotoxic agent used as a positive control exhibited 59.7% hepatoprotective activitiy at 100 µg/ml. Moreover, we tested the effect of REE on carbon tetrachloride (CCl4)-induced liver toxicity in rats. REE at dose of 50 and 100 mg/kg and silymarin at dose of 50 mg/kg were orally administered to CCl4-treated rats. The results showed that REE and silymarin significantly reduced the elevated levels of serum enzyme markers induced by CCl4. The biochemical data were supported by evaluation with liver histopathology. These findings suggest that REE, can significantly diminish hepatic damage by toxic agent such as tacrine or CCl4.

Effect of Microalgal Extracts of Tetraselmis suecica against UVB-Induced Photoaging in Human Skin Fibroblasts.

Exposure of cells to ultraviolet B (UVB) radiation can induce production of free radicals and reactive oxygen species (ROS), which damage cellular components. In addition, these agents can stimulate the expression of matrix metalloproteinase (MMP) and decrease collagen synthesis in human skin cells. In this study, we examined the anti-photoaging effects of extracts of Tetraselmis suecica (W-TS). W-TS showed the strongest scavenging activity against 2,2-difenyl-1-picrylhydrazyl (DPPH) and peroxyl radicals, followed by superoxide anions from the xanthine/xanthine oxidase system. We observed that the levels of both intracellular ROS and lipid peroxidation significantly increased in UVB-irradiated human skin fibroblast cells. Furthermore, the activities of enzymatic antioxidants (e.g., superoxide dismutase) and the levels of non-enzymatic antioxidants (e.g., glutathione) significantly decreased in cells. However, W-TS pretreatment, at the maximum tested concentration, significantly decreased intracellular ROS and malondialdehyde (MDA) levels, and increased superoxide dismutase and glutathione levels in the cells. At this same concentration, W-TS did not show cytotoxicity. Type 1 procollagen and MMP-1 released were quantified using RT-PCR techniques. The results showed that W-TS protected type 1 procollagen against UVBinduced depletion in fibroblast cells in a dose-dependent manner via inhibition of UVB-induced MMP-1. Taken together, the results of the study suggest that W-TS effectively inhibits UVB-induced photoaging in skin fibroblasts by its strong anti-oxidant ability.