Determination of biogenic amines in <Emphasis Type="Italic">Cheonggukjang</Emphasis> using ultra high pressure liquid chromatography coupled with mass spectrometry

A rapid and reliable method for the simultaneous determination of 12 biogenic amines (BAs; agmatine, phenylethylamine, tyramine, putrescine, cadaverine, histamine, serotonin, tryptamine, spermidine, noreinephrine, dopamine, and spermine) in cheonggukjang was optimized and validated using ultra high pressure liquid chromatography-electrospray tandem mass spectrometry (UHPLC-ESI-MS/MS). The BAs were dansylated and separated on a C8 column under LC gradient of 7 min duration, and detected by MS/MS with the multiple reaction monitoring mode (MRM). This method exhibited excellent linearity for all of the analytes with correlation determination (R²) higher than 0.98. The limits of detection (LODs) were 10.8–39.6 μg/kg. The precision results were expressed as relative standard deviation (RSD), ranged from 0.3 to 14.3% for intra-day and from 0.9 to 15.4% for the interday. The proposed method will help to ensure for quality control by monitoring of BAs in cheonggukjang.     

Structure and disorder in MgSiO3 glasses above megabar pressures via nuclear magnetic resonance: DFT calculations

The structural modifications in oxide glasses under extreme compression may account for the pressure-induced increase in their mechanical toughness and rigidity, rendering potential for technological applications of the compressed glasses. High-resolution solid-state nuclear magnetic resonance has provided a structural information regarding glasses by identifying how nuclear spins behave and interact with nearby elements. However, knowledge of nuclear spins resonance in oxide glasses under extreme pressure above 1 million atmospheres has not been available, making the origins of glass densification illusive. In this article, ab initio calculations of prototypical magnesium silicate glasses quantify how structural changes in glasses affect the nature of nuclear spin interactions at high pressure beyond megabars. The calculated results establish novel correlations between pressure-induced evolution of atomic structures, such as oxygen and cation coordination numbers, bond angle and lengths, and structurally relevant nuclear magnetic resonance parameters for Mg, Si, and O in compressed oxide glasses above megabar pressures. The established correlations highlight that the nuclear spins in glasses can serve as a new indicator to the extreme densification paths. Pressure-induced dispersion in nuclear spin parameters also reveals an overall increase in the topological entropy. This entropy gain may weaken glasses at an elevated pressure conditions, accounting for potential softening of the compressed glasses. The proposed relationships open a new window to the evolution of diverse complex glasses under extreme stress and compression with high-resolution solid-state nuclear magnetic resonance.     

Simultaneous determination of trichothecene mycotoxins in cereals by LC-MS/MS

Food Science and Biotechnology - This study was designed to determine the residual trichothecene mycotoxins in cereal samples. The optimal solvent for extraction was 84% (v/v) aqueous acetonitrile...     

Effects of vanadium carbides on hydrogen embrittlement of tempered martensitic steel

Precipitation of V carbides is known to suppress the hydrogen-embrittlement (HE) phenomenon as well as to increase material strength. Despite increasing attention to V carbides, there have been few systematic and quantitative investigations on their effects on HE resistance. This study reveals the role of V carbides on the HE behavior of tempered martensitic steel while eliminating other factors, such as chemical composition of other elements, mechanical strength, and dislocation density. The amount of trapped hydrogen increased with increasing V content, whereas the best HE resistance was attained at 0.2 wt% V and it decreased with further V addition. V carbide was considered as a non-diffusible hydrogen-trapping site in this study. However, excessive V content led to the formation of large undissolved carbides that gave rise to brittle fracture and decreased HE resistance. This study suggests that improved HE resistance can be achieved by minimizing the size and amount of undissolved V carbides.     

High temperature oxidation resistance of Ni-(5∼13)Co-(10∼16)Cr-(5∼9)W-5Al-(1∼1.5)Ti-(3∼6)Ta alloys

The oxidation behavior of Ni-based superalloys was examined by cyclic oxidation tests at 850 and 1000 °C. The present study focused on the investigation of two newly developed and three commercial alloys (GTD-111, IN738LC, and CM247LC). The oxidation resistance of the superalloys were evaluated by the oxidation rate constants and the mass gains. The oxidation scales mainly consisted of outer Cr₂O₃ and inner Al₂O₃ layers at both temperatures, as well as oxides of minor elements such as TiO₂, NiCr₂O₄, CrTaO₄, HfO₂, and TaO. The oxidation resistance of the alloys containing larger amounts of Al, W, and Ta and lower Mo and Ti concentrations was higher than those of the other alloys. The ranking of oxidation resistance for the alloys corresponded to the statistical prediction drawn from a response surface analysis. Furthermore, these alloys contained more Ta oxides, such as CrTaO₄ and TaO, suggesting that Ta oxides had an active role in improving the oxidation resistance.     

Inhibitory effect of oral administration of Sangwhang mushroom (Phellinus linteus) grown on germinated brown rice on experimental lung metastasis and tumor growth in mice

Here, the effect of oral administration of the extract of sangwhang mushroom (Phellinus linteus, PL) grown on germinated brown rice on lung metastasis of tumor cells was examined in mice, and a possible immunological action was suggested. Oral administration of the extract of sangwhang mushroom grown on germinated brown rice (PB, 90 mg/kg) prior to tumor inoculation significantly inhibited experimental lung metastasis produced by colon 26-M3.1 carcinoma cells. Also oral administration of PB after tumor inoculation significantly inhibited experimental lung metastasis of tumor cells. In addition, oral administration of PB significantly suppressed tumor growth as well as tumor-induced angiogenesis. However, neither PL nor germinated brown rice (BR) was active. Oral administration of PB, but not PL and BR, resulted in a significant enhancement of natural killer (NK)-mediated killing activity against tumor cells. These results suggest that oral administration of PB can induce antitumor activity to inhibit tumor metastasis, and its antitumor effect is associated with NK cell activation.     

Flexible auto balancer design for the reduction of optical disk drive vibration

This study investigates the design of a flexible auto balancer (FAB) for the compensation of disk eccentricity. The FAB has various advantages over a conventional auto ball balancer, such as low cost, ease of implementation, lack of noise and applicability to standing-type drives. For the FAB design, a finite element model is developed considering the prestress effect and spin-softening effect caused by rotation. The structure is optimized and fabricated based on finite element model verification via modal testing. In addition, the dynamic behavior of the FAB is recorded by high-speed photography, and the vibration transmission to the base deck is measured.     

Measurement of total phenolic content in wine using an automatic Folin–Ciocalteu assay method

Measuring the total phenolic content in wine is important in estimating the taste and health benefits of wine. We developed an automatic Folin–Ciocalteu (F‐C) method to reduce processing times (3 min), human errors and waste volume as compared it to the manual method. The gallic acid standard responded linearly up to 5000 μg mL^?1, and the wine dilution series responded linearly between four‐ and sixteenfold dilutions. Anthocyanins showed slower reaction rate compared with wine, gallic acid and quercetin, while ascorbic acid showed the fastest rate. Fructose and glucose at the 10% level showed approximately 8% interference in port wines, and the interference was thought to be negligible in most dry wines containing <1% sugar. Total phenolic contents ranged between 1600 and 3300 μg mL^?1 by the automatic method and were approximately 20% less than those by the manual method, except in pink wines which was nearly identical. The regression analysis of the phenolic contents showed a very linear relationship between the methods (r² = 0.97***). This automatic method was thought to be efficiently adopted in wine testing laboratories as a fast and reproducible assay.     

Effect of temperature on the relationship between moisture content and dynamic rheological properties of Korean honey

Dynamic rheological properties of 27 Korean honeys with various moisture contents (16.2–20.1%) were evaluated at different temperatures (−5, 0, 5, 10, and 20°C) and were then correlated with moisture content. Dynamic moduli increased with a decrease in temperature while their predominant increases were noticed at −5°C. The relationships between moisture content and dynamic moduli seem to be influenced by temperature, and their correlations increased in the following order: −5>0>5 >10>20°C, showing greater determination coefficients (R²=0.942−0.966) at −5°C as compared to the other temperatures. In particular, the G″ at sub-zero temperatures had a better correlation (R²=0.965−0.966) than G′ (R²=0.899−0.942), indicating that the viscous property more closely correlated with moisture content as compared to the elastic property. This suggests that G″ determined at subzero temperatures can be useful for estimating the quality of honey.