Lubrication Property of Magnetorheological Fluid With Nano-Silica Additives Under Magnetic Field

Magnetorheological(MR)fluid is colloidal suspension and stiffens into semi-solid when subjected to a magnetic field.In order to investigate the effect of magnetic field on lubrication property of MR fluid with nano-silica additives,a pin-on-disc tribometer is used to carry out friction and wear experiment of steel under the magnetic field.The MR fluids with different additive concentrations are prepared and their theological properties are examined via a rotational rheometer.Different lubrication performance of the MR fluid with nano-silica additives with and without magnetic field is presented.In addition,through observing the morphology and analyzing the elemental composition of the worn surfaces,the effects of additives on the lubrication property are investigated.     

Water footprint for Korean rice products and virtual water trade in a water-energy-food nexus

ABSTRACT

One possible approach for addressing water and food insecurity involves food production, trade, and water used elsewhere. In this study, we introduce a water footprint for Korean rice products and focus on the impacts of localized cultivation and water supply systems on the water footprint. In addition, we discuss several studies on the application of water footprint and virtual water trade in water and food management in Korea. Finally, we suggest the role of water footprint and virtual water trade in sustainable resource management through a water-energy-food nexus approach.     

Effect of aging treatment on irradiation-induced segregation of high Mn-Cr steel

To investigate the effect of aging treatment on irradiation-induced segregation of high Mn-Cr steel, specimens for electron-beam irradiation were prepared from the high Mn-Cr austenitic steel which was solution treated at 1 373 K for 1 h and aging treated at 573 K for 1 000 h, respectively. The electron-beam irradiation was performed at 573 K up to doses of 5.4 dpa in a 1 250 kV HVEM and irradiation-induced segregation analyses were carried out by an EDX in a 200 kV FE-TEM. The results show that void formation is not observed in both solution treated and aging treated ones. The amount of Cr segregation at the grain boundary decreases in the aged one; however, that of Mn is not changed in solution treated one.     

Dicaffeoylquinic acid derivatives and flavonoid glucosides from glasswort (Salicornia herbacea L.) and their antioxidative activity

Two novel antioxidant compounds, isoquercitrin 6″-O-methyloxalate (6) and methyl 4-caffeoyl-3-dihydrocaffeoyl quinate (salicornate, 7), were isolated from Salicornia herbacea L.. Six known compounds were also identified as 3,5-dicaffeoylquinic acid (1), quercetin 3-O-β-d-glucopyranoside (2), 3-caffeoyl-4-dihydrocaffeoylquinic acid (3), methyl 3,5-dicaffeoyl quinate (4), 3,4-dicaffeoylquinic acid (5), and isorhamnetin 3-O-β-d-glucopyranoside (8). Their chemical structures were determined by spectroscopic data from ESI–MS and NMR. The isolated dicaffeoylquinic acid derivatives (1, 3, 4, 5, and 7) showed similar activities for scavenging 1,1-diphenyl-2-picrylhydrazyl radicals and inhibiting formation of cholesteryl ester hydroperoxide during copper ion-induced rat blood plasma oxidation. The two flavonol glucosides (2 and 6), which have no substitutions in the B ring of their aglycones, also had similar activity. However, compound 8, which has the same structure as 2 except for the presence of a methoxyl group in the C-3′ position of the B ring, showed predominantly lower antioxidant activity than the other isolated compounds.     

EVALUATION OF YUKWA (A KOREAN OIL-PUFFED RICE SNACK) EXPANSION WITH INCREASES IN WATER-STEEPING DURATION OF WAXY RICE USING IMAGE ANALYSIS

Abstract Yukwa, a Korean oil-puffed rice snack with a soft texture, is currently being manufactured primarily by traditional methods. The water-steeping time of the milled waxy rice is an important factor because it has a great effect on the product quality. The expansion rates related to water-steeping durations, which are indices of Yukwa quality, were quantitatively evaluated using image analysis. The longer the water-steeping time was, the higher were the expansion parameters of the Yukwa . When the waxy rice was water-soaked over 6 days, the expansion rate of the Yukwa showed a statistically significant increase. Using these expansion rates, the diameter and diameter-implicit parameters were statistically modeled with respect to the moisture content of the rice at P 0.01. Hedonic sensory evaluation for Yukwa showed that the longer raw waxy rice was water-steeped. The better quality was due to high expansion.     

Numerical optimization study to install air curtain in a subway tunnel by using design of experiment

Subways are a major mode of public transportation in metropolitan cities. A proper ventilation system is required to maintain indoor air quality in subway tunnels. Platform screen doors improve the platform environment but degrade air quality in subway tunnels. Trains transport fine particles from the tunnel into the platform. An air curtain installation in the subway tunnel permits traffic and reduces the transfer of bacteria and fine particles. The existing tunnel of Seoul subway was investigated by using computational fluid dynamics and design of experiment method for optimum air curtain installations. The flow field of the subway tunnel was computed by using ANSYS CFX software. Minitab software was used to generate the design process and to analyze the computational results. The computational domain of the existing tunnel included two natural ventilation shafts, one mechanical shaft, and the twin tracks. The height, width, and length of each track were 6, 4, and 400 m, respectively. The air curtain installation area was located between the natural and the mechanical ventilation shafts of Rrack 1. The design variables for the optimization study were the width, velocity, and installation location of the air curtain. The object function for optimization was mass flow rate at the natural ventilation shaft. The length of the air curtain was fixed at 4 m. The predicted mass flow rates were analyzed with the design variables by using the response surface method (RSM). The optimum values of the design variables, i.e., velocity, width, and installation location were 25 m/s, 0.2 m, and 5.8195 m, respectively. The maximum mass flow rate with the optimum design values was 114.4447 kg/s. The optimum values of the design variables were validated by computing the tunnel with the optimum values from RSM. The mass flow rate in the natural ventilation shaft 1 was 114.2 kg/s, as predicted. The optimization study can be helpful to set the optimum design conditions for the subway ventilation system.     

EFFECTS OF SESAME LIGNAN EXTRACT ON LINOLEIC ACID, LIPID OXIDATION, COLOR AND TEXTURAL PROPERTIES OF GROUND PORK, AND SAUSAGE PRODUCTS

Sesame lignan extract was prepared from roasted sesame oil and added at 0.02, 0.05, 0.10 and 0.20% (w/w) to linoleic acid and ground pork products. Cooked ground pork containing more than 0.02% of lignan extract showed TBA values lower than those containing butylated hydroxyanisole (BHA) during storage. Sausages containing 0.05% of lignan extract had lower thiobarbituric acid (TBA) values when stored at 4C for 14 days; they also showed higher CIE color values than the control meat sample (P < 0.05). There were no differences in textural properties such as hardness, cohesiveness and chewiness between the control and the sausages containing lignan extract when determined by Instron Testing Machine. Thus, lignan extract prepared from roasted sesame oils was highly antioxidative when used in cooked ground pork at > 0.02% or in sausages at > 0.05%.     

STABILIZATION OF GROUND GARLIC COLOR BY CYSTEINE, ASCORBIC ACID, TRISODIUM PHOSPHATE AND SODIUM METABISULFITE

Various organic and inorganic compounds at different concentrations were added to ground garlic as a means of controlling changes in color. Among the compounds tested, cysteine (C), ascorbic acid (A), sodium metabisulfite (S) and trisodium phosphate (P) were found effective in preventing a change in color towards greening. When these compounds were mixed at 0.1 M level, their binary mixtures (CS, AS, SP, AC) and ternary/quaternary mixtures (CAP, CAS, CSP, CASP) turned out to be even more effective for sustaining the original color values (L = 45, a = -2, b = 10) of ground garlic. Although the controlling effect was somewhat decreased with a reduction in mixture concentration from 0.1 to 0.03 M, the majority of mixtures (CS, SP, CAP, CAS, CSP and CASP) still maintained their effectiveness in color control.     

CALCIUM CHLORIDE EFFECTS ON TBA VALUES OF COOKED MEAT

Ground chicken breast and beef top round (semimembranosus) muscles were treated with CaCl₂ (0.05, 0.10, 0.15, and 0.20% on final sample weight basis) and cooked to an internal temperature of 80C. Cooked samples were aerobically stored at 4C for 0 or 4 days and analyzed for 2-thiobarbituric acid (TBA)-reactive substances. Results indicated that CaCl₂ can either inhibit or accelerate lipid oxidation in cooked meat depending on its concentration/meat animal species. TBA values of chicken samples were decreased by CaCl₂ used at ≥ 0.1% of final weight. However, only beef samples treated with the highest CaCl₂ level (0.20%) tended to have lower TBA values when compared to control samples (treated with deionized water only). CaCl₂ used at low levels (0.05% for chicken and ≤0.15% for beef) tended to elevate cooked meat TBA values.