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In this study, high-damping and conducting epoxy nanocomposites were developed with carbon nanofibers as conducting materials, and zinc oxide particles as piezoelectric materials. The mechanical and electrical properties, electrical impedance, and loss factors were investigated by uniaxial tensile tests, voltage measurement, impedance measurement, and 3-point bending tests. Two percolation thresholds were found: the percolation threshold of resistivity due to the carbon nanofibers forming conductive networks in the matrix; and the impedance threshold due to the zinc oxide particles acting like electric barriers. A poling treatment of the high-damping and conducting epoxy nanocomposite was considered, and we found that poling treatment helped to make the networks more conductive and to generate voltage from ZnO particles. A high-damping and conducting epoxy nanocomposite with 3 wt% CNF and 10 wt% ZnO exhibited higher loss factor than those of others tested.

An HPLC method combined with immunoaffinity clean-up was developed for the simultaneous analysis of deoxynivalenol (DON), nivalenol (NIV), and 3-acetyldeoxynivalenol (3AcDON) in grains and feeds. The limits of quantification of the method for DON, 3AcDON, and NIV were 11.0, 27.6, and 13.5 ng/g, respectively. HPLC analyses of 300 samples of grains and feeds collected in South Korea showed that the incidence of DON and NIV in corn was 22.5 and 7.5%, while that in rice was 4.0 and 54.0%, respectively. The incidence of DON and NIV in mixed grain powder was 62.0 and 24.0%, respectively. Our study also showed that animal feeds were mainly contaminated with DON (98.1%) in the range of 32.8–950.25 ng/g with the mean concentration of 353.32 ng/g. The levels of DON in grains did not exceed the maximum allowable limit (1 mg/kg) set by the Korean Food and Drug Administration.

A rapid and highly sensitive method for the quantification of manidipine in human plasma was developed. Cleanup utilizing a 96-well solid-phase extraction technique is a simple and high– throughput method for extracting both manidipine and its internal standard felodipine from the quality- control samples: 97.5±2.1% for manidipine and 95.6±2.5% for IS. The ultra-performance liquid chromatography (UPLC) with tandem mass spectrometry (MS/MS) analytical tool, operated in a selective reaction monitoring mode was validated for manidipine quantification. The limit of detection and the lower limit of quantification were found to be 0.03 and 0.07 ng/mL, respectively. The intra- and inter-day precision was <3%, and accuracies ranged from 93.6 to 98.3%. A combination of the high-throughput SPE cleanup, and the sensitive and robust UPLC–MS/MS detection of manidipine at the picogram level was successfully applied to a bioequivalence study; Tmax, Cmax, and AUC0-12 obtained from reference tablet were averaged at 2.26 h, 5.78 ng/mL, and 20.82 ng h/mL, whereas those from test one were at 2.31 h, 5.64 ng/mL, and 21.37 ng h/mL, respectively.

ABSTRACTSurvival of fungal species depends on the ability of these organisms to respond to environmental stresses. Osmotic stress or high levels of reactive oxygen species (ROS) can cause stress in fungi resulting in growth inhibition. Both eukaryotic and prokaryotic cells have developed numerous mechanisms to counteract and survive the stress in the presence of ROS. In many fungi, the HOG signaling pathway is crucial for the oxidative stress response as well as for osmotic stress response. This study revealed that while the osmotic stress response is only slightly affected by the master regulator veA, this gene, also known to control morphological development and secondary metabolism in numerous fungal species, has a profound effect on the oxidative stress response in the aflatoxin-producing fungus Aspergillus flavus. We found that the expression of A. flavushomolog genes involved in the HOG signaling pathway is regulated by veA. Deletion of veAresulted in a reduction in transcription levels of oxidative stress response genes after exposure to hydrogen peroxide. Furthermore, analyses of the effect of VeA on the promoters of cat1and trxBindicate that the presence of VeA alters DNA-protein complex formation. This is particularly notable in the cat1promoter, where the absence of VeA results in abnormally stronger complex formation with reduced cat1expression and more sensitivity to ROS in a veAdeletion mutant, suggesting that VeA might prevent binding of negative transcription regulators to the cat1promoter. Our study also revealed that veApositively influences the expression of the transcription factor gene atfBand that normal formation of DNA-protein complexes in the cat1promoter is dependent on AtfB.

In this study, we investigated the occurrence of aflatoxins (AFs) and ochratoxin A (OTA) in mejuand soybean paste produced in South Korea. Samples were collected from three regions divided on the basis of climate in South Korea. A total of 100 mejusamples were analyzed over 3 years (2012–2015), and 45 soybean paste samples were analyzed in 2016. Mycotoxins were extracted with an immunoaffinity column method and quantified by high-performance liquid chromatography. AFs were detected in 10 of meju(10%) and 11 of soybean paste samples (24.4%) with concentrations of 0.2–48.3 μg/kg and 0.88–16.17 μg/kg, respectively. OTA was detected in 50 of meju(50%) and 22 of soybean paste samples (48.9%) with concentrations of 0.1–193.2 μg/kg and 0.88–26.29 μg/kg, respectively. Mycotoxin contamination in mejuwas more common in the central region than in the southern areas. Thus, more mycotoxins were produced in the central region owing to less fungal competition in mejuduring fermentation inside households. We also found that about 91% of AFs and 73% of OTA in mejuwere degraded after the production of soybean paste and soy sauce. Even after degradation of AFs and OTA, the levels of AFB1and OTA were 0.5 µg/kg and 7.5 µg/kg in soy sauce and 11.9 µg/kg and 190.4 µg/kg in soybean paste, respectively. Thus, our results suggest the need for constant monitoring of mejuand soybean paste for AFs and OTA.