• Analytical Science and Technology
• /
• v.22 no.4
• /
• pp.326-335
• /
• 2009

A specific analytical method able to identify and quantify traces of six glucocorticoids residues in eggs were developed. The extraction and clean-up parameters for simultaneous analysis were evaluated and HPLC and spectrometric conditions were also established. For determination of glucocorticoids, 5 g of egg was transferred into a test tube, adjusted pH 5.2 with acetate buffer and was $\beta$-glucuronidase/arylsulfatase from Helix pomatia added. The mixture was centrifuged and supernatant was extracted twice with 20 mL n-hexane. The extraction was performed with HLB cartridge using methanol, followed by clean-up with silica cartridge using methanol/ethyl acetate (4/6, v/v). The analytes were determined by HPLC/ESI-MS/MS operating in the negative ion mode. Validation studies with fortified egg samples for established method were performed. The result of method validation gave good efficiency, linearity, accuracy and precision. The correlation coefficients ($r^2$) of the calibration curves appeared to be higher than 0.99 in egg, indicating excellent linearity. LOD was ranged 0.09 to $0.17{\mu}g/kg$, and recoveries for most compounds were in the range of 55.7-69.8%. This method can be used to determine ${\mu}g/kg$ levels of glucocorticoids in eggs.

• Applied Chemistry for Engineering
• /
• v.35 no.1
• /
• pp.16-22
• /
• 2024

Polymer electrolyte membrane fuel cells have the advantage of low operating temperatures and fast startup and response characteristics compared to others. Simulation studies are actively researched because their cost and time benefits. In this study, the resistance of water residual in the gas diffusion layer (GDL) of the unit cell was added to the existing equation to compare the actual data with the model data. The experiments were conducted with a 25 cm² unit cell, and the samples were separated into stopping times of 0, 10, and 60 minutes following primary impedance measurement, activation, and polarization curve data acquisition. This gives 0, 10, and 60 minutes for the residual water in the GDL to evaporate. Without the rest period, the magnitude of the performance improvement was not significantly different at the same potential and flow rate, but the rest period did improve the performance of the membrane electrode assembly when measuring impedance. By changing the magnitude of the resistance reduction to an overvoltage, the voltage difference between the fuel cell model with and without residual water was compared, and the error rate in the high current density region, which is dominated by concentration losses, was reduced.

• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.2
• /
• pp.204-208
• /
• 2012

Water repellency which affects infiltration, evaporation, erosion and other water transfer mechanisms through soil has been observed under several natural conditions. Water repellency is thought to be caused by hydrophobic organic compounds, which are present as coatings on soil particles or as an interstitial matter between soil particles. This study was conducted to evaluate the characteristics of the water repellent soil and transport characteristics of trace elements within this soil. Capillary height of the water repellent soil was measured. Batch and column studies were accompanied to identify sorption and transport mechanism of trace elements such as $Cu^{2+}$, $Mn^{2+}$, $Fe^{2+}$, $Zn^{2+}$ and $Mo^{5+}$. Difference of sorption capacity between common and repellent soils was observed depended on the degree of repellency. In the column study, the desorption of trace elements and the spatial concentration distribution as a function of time were evaluated. The capillary height was in the repellency order of 0% > 15% > 40% > 70% > 100%. No water was absorbed in soil indicating >70% repellency. Using trace elements, $Fe^{2+}$ and $Mo^{5+}$ showed higher sorption capacity in the repellent soil than in non-repellent soil. The sorption performance of $Fe^{2+}$ was found to be in the repellency order of 40% > 15% > 0%. Our results found that transfer of $Mo^{5+}$ had similar sorption tendency in soils having 0%, 15% and 40% repellency at the beginning, however, the higher desorption capacity was observed as time passes in the repellent soil compared to in non-repellent soils.

• Korean Journal of Soil Science and Fertilizer
• /
• v.23 no.1
• /
• pp.8-14
• /
• 1990

Retardation and hydrodynamic dispersion coefficient necessary for model of water and solute movement in a soil were determined for horizontal soil column with different initial soil water conditions. The soil columns were compacted with sandy loam soil. The bulk density was $1,350+50kg/m^3$, and initial water contents were 0.05, 0.08 and 0.14. Advancement of 0.05% $CaSO_4$ solution was used as the standard and advancements of 0.5% KCl, $CaCl_2$ and $KH_2PO_4$ were compared. Retardation of non-reactive $Cl^-$ was related with the initial soil water content, ${\theta}n$, as ${\theta}/({\theta}-{\theta}n)$, and anion exclusion was ignored. Retardations of active $K^+$, $Ca^{{+}{+}}$ and $H_2PO_4{^-}$ were related as 1/(R+1) $^*{\theta}/({\theta}-{\theta}n)$, in which R was retardation coefficient. Measured R was 0.64 for $K^+$, 0.80 for $Ca^{{+}{+}}$ and 2.6 for $H_2PO_4{^-}$, respectively. Calculated R using Langmuir adsorption isotherm showed fair degree of applicability. Soil water diffusivity, $D({\theta}),m^2/sec$, calculated for different initial water content showed unique function as $$log(D({\theta}))=13.448{\theta}-9.288$$ Hydrodynamic dispersion coefficient of $Cl^-$ above soil water content 0.36 was similar to soil water diffusivity and decreased to near self diffusion coefficient at soil water content near 0.2. Those of $K^+$, $Ca^{{+}{+}}$ $H_2PO_4{^-}$ at soil water content of 0.38 were $5.5{\times}10^{-6}$, $2.4{\times}10^{-6}$ and $7.1{\times}10^{-7}m^2/sec$ and decreased rapidly with decreasing soil water content lower than 0.36.

• Korean Journal of Food Science and Technology
• /
• v.48 no.2
• /
• pp.178-186
• /
• 2016

The present study was conducted to investigate the effect of whole wheat bread with added Lindera obtusiloba (LO) and Capsosiphon fulvescens (CF) ethanol extracts on serum glucose and lipid levels in Sprague Dawley rats. Rats were divided into five groups depending on the diet administered: normal bread (NC), whole wheat bread (W), whole wheat bread with LO leaves extract (WL), whole wheat bread with CF extract (WC), and whole wheat bread with freeze-drying CF (WDC). After 4 weeks of consuming the experimental diet, the blood glucose level and hemoglobin A1c contents were found to be significantly lower in the W, WL, WC, and WDC groups than in the NC group. The high-density lipoprotein-cholesterol levels increased in the WL group when compared to those in the NC group and triglycerides levels decreased in all wheat groups compared to those in the NC group. These results suggest that wheat breads containing LO and CF extracts are effective for preventing hypercholesterolemia and obesity.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.32 no.4
• /
• pp.603-607
• /
• 2003

To investigate the alcohol metabolizing system in liver of rats drunken 10% ethanol with Monascus pigment extract (MPE), Sprague-Dawley male rats weighing about 250 g have been drunken 10% ethanol containing 1, 2.5 and 5% Monascus pigment extract for a month. Three groups of rats drunken 10% ethanol with MPE gained somewhat less body weight than normal group, but the changes of body weight was not significantly different among the former groups. All groups drunken MPE supplemented alcohol had no remarkable changes in liver function on the basis of liver weight/body weight, the serum levels of alanine aminotransferase and xanthine oxidase activity. 10% alcohol drunken animals (control group) showed significantly increased activity of hepatic alcohol dehydrogenase (ADH) by 87% compared with normal group and the animals drunken 1%, 2.5% and 5% MPE showed respectively 34%, 29% and 21% increased activity of hepatic ADH, whileas Km value of ADH in 1, 2.5 and 5% MPE group decreased by 40%, 30% and 19% respectively compared with the control, but Vmax showed no significant changes among MPE groups. In case of aldehyde dehydrogenase (ALDH), 1% MPE group showed significantly increased activity by 32% and 2.5% or 5% MPE group showed increasing tendency compared with control, and Km value in three experimental groups declined by 27% and no particular changes were found among those. Furthermore, Vmax value in 1, 2.5 and 5% MEP group increased by 88,56 and 22% respectively with the control. In the aspect of the area under the curve of a ethanol concentration versus time (AUC) profile obtained after administration of 10% alcohol with 1 or 5% MPE, the decreasing rate of AUC to the control was 18% in 1% MPE treated rats whereas 10% in 5% MPE group.

• Applied Biological Chemistry
• /
• v.20 no.2
• /
• pp.205-209
• /
• 1977

The pool size of plasma glucose, turnover rate and other concerned items for glucose metabolism in normal laying hen were investigated by a single-injection method using $U-C^{14}-glucose$. The 11.6 nCi of pure dose was injected to a hen normally fed through the wing vein. The glucose concentration in plasma sample taken at 5 minutes after injections was 214mgper 100ml. From the plottings of logarithmic standard specific activities of plasma taken from 5 to 120 minutes against the time after injection and from the regresion analysis, metabolic states were determined. The pool size was 1.07g, turnover rate was 0.024 per minute, turnover time was 41 minutes, utilization rate was 26mg/min. (0.83 g/hr/kg B.W. 3/4) and glucose space(extracellular fluid volume) was 25.3 per cent of body weight. The values obtained from. 10-50 minutes samples were similar to those described above, which we from 5-120 minutes samples.

• Journal of Animal Science and Technology
• /
• v.44 no.5
• /
• pp.573-584
• /
• 2002

Milk urea nitrogen (MUN) and Milk protein (MP) are being used as indicators of the protein-energy balance and for actual farm feeding practices. The purpose of this study was to investigate the MUN and MP concentrations of individual cows and bulk tank milk to evaluate the dietary protein-energy balance from lactating Holstein cows. Mean MUN and MP concentrations in the milk samples obtained from 132,636 cows of 4,856 herd during Jan. 1999 to Dec. 2001 were 16.2 5.2mg/dl and 3.30 0.35%, respectively. The highest values were found during summer and lowest valued during winter in MUN. But, the average contents of MP were the highest during winter and the lowest during summer. In order to evaluate protein-energy balance for feeding, we set the level of recommended MP range of 2.90${\sim}$3.29% in early lactation considering a negative energy balance. The recommended level of MP in mid-lactation and late lactation were set as 3.10${\sim}$3.49%, and 3.30${\sim}$3.69%, respectively. Recommended MUN range of 12${\sim}$18 mg/dl was determined through the whole lactation period. Individual cows milk were analyzed by the 9 types based on this levels of MP and MUN in this study. Among the total cows investigated, 26.8%, 25.8%, and 22.2% have shown the recommended criteria of MP and MUN values, respectively. Also, of total herds surveyed, 11.6% had MUN values lower than 12.0 mg/dl and 32.9% had values higher than 18.0 mg/dl and 44.5% of total herd have not met with the recommended criteria of MP values in bulk tank milk. In case of MP, out of the total herd surveyed, 26.0% had MP values lower than 3.10% and 24.0% had values higher than 3.30% and 50.0% had MP values outside the recommended interval (3.1${\sim}$3.3%). This study has indicates that many dairy farms are under improper feeding management practice of the dietary protein-energy balance.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.24 no.1
• /
• pp.21-29
• /
• 2016

We mix food waste leachate and sewage sludge by the proportion of 1:9, 3:7 and 5:5. It turns out that they produced 233, 298 and 344 $CH_4{\cdot}mL/g{\cdot}VS$ of methane gas. The result suggests that as the mixing rate of food waste leachate rises, the methane gas productions increases as well. And more methane gas is made when co-digesting sewage sludge and food waste leachate based on the mixing ratio, rather than digesting only sewage sludge alone. Modified Gompertz and Exponential Model describe the BMP test results that show how methane gas are produced from organic waste. According to the test, higher the mixing rate of food waste leachate is, higher the methane gas productions is. The mixing ratio of food waste leachate that produces the largest volume of methane gas is 3:7. Modified Gompertz model and Exponential model describe the test results very well. The correlation values($R^2$) that show how the results of model prediction and experiment are close is 0.92 to 0.98.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.9 no.1
• /
• pp.43-55
• /
• 1976

Fertilization and early development of turbo cornutus was studied based on the samples which were collected in Yeosu area. Particular emphasis was paid on induction of artificial spawing, fertilization rate, preembryonic development, the growth of the early larva and larval survival to various salinity. Among the various methods for induction of artificial spawning which have been tested for the present study, drying by exposure to air is the. most efficient, and percentage fertilization rate was $83.8-96.4\%$. The diameter of fertilized eggs was $0.182{\pm}0.0028mm$; and the diameter of egg membrane was $0.245{\pm}0.093mm$. Under the temperature range of $20.6-25.4^{\circ}C$ the larvae hatched out after 11:05-11:15 hours of fertilization. After 3.0-3.5 days of fertilization the planktonic larvae begand to settle, and the settlement terminated within 5 days. During the period of 150 days of early culturing the diameter growth of shell(M) and the diameter of shell aperture(A) was formulated as follows: $$1972\;M=0.33e^{0.02070D}$$ $$A=0.19e^{0.02282D}$$ $$1973\;M=0.32e^{0.02282D}$$ $$A=0.16e^{0.02596D}$$ During the same period of early culturing the relative growth of shell diameter and the diameter of shell aperture was formulated as follows : 1972 A=0.6478 S-0.1575 1973 A=0.5897 S-0.0515 After 11 days of larval hatching $0.02-0.18\%$ of planktonic larvae settled. After 150 days of settlement the survival rate of the early shells was $7.4-21.6\%$. Under the temperature range of $21.0-22.7^{\circ}C$ the optimum salinity range for the development of egg and the planktonic larvae was $30-35\%_{\circ}$.