• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2774-2780
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• 2013

Two new isostructural dinuclear complexes, $Ln_2(4-cpa)_6(bpy)_2$ (Ln = Eu (1); Tb (2), 4-cpa = 4-chlorophenylacetate, bpy = 2,2'-bipyridine), have been hydrothermally synthesized and characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis (TGA), powder X-ray diffraction and single-crystal X-ray diffraction. The lanthanide ions are bridged by two bidentate and two terdentate carboxylate groups to give centrosymmetric dimers with $Ln{\cdots}Ln$ separations of 3.967(2) and 3.956(3) ${\AA}$, respectively. Each metal atom is nine-coordinate and exhibits a distorted tricapped trigonal prismatic geometry. Three-dimensional fluorescence spectra show that both 1 and 2 emit bright red and green luminescence at room temperature, with long lifetimes of up to 0.369 ms (at 614 nm) and 0.432 ms (at 543 nm), respectively. Moreover, poor luminescence efficiency has been noted for complex 2. The 4-Hcpa ligand and complexes 1-2 have been screened for their phytogrowth-inhibitory activities against Brassica napus L. and Echinochloa crusgalli L., and the results are compared with the activity of quizalofop-P-ethyl.

• Korean Journal of Materials Research
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• v.28 no.10
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• pp.551-563
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• 2018

Visible and IR windows require a combination of high optical transparency and superior thermal and mechanical properties. Materials, fabrication and characterization of transparent ceramics for visible/IR windows are discussed in this review. The transparent polycrystalline $Y_2O_3$, $Y_2O_3-MgO$ nanocomposites and $MgAl_2O_4$ spinel ceramics are fabricated by advanced ceramic processing and the use of special sintering technologies. Ceramic processing conditions for achieveing fully densified transparent ceramics are strongly dependent on the initial powder characteristics. In addition, appropriate use of sintering technologies, including vacuum sintering, hot-pressing and spark plasama sintering methods, results in outstanding thermal and mechanical properties as well as high optical transparency of the final products. Specifically, the elimination of light scattering factors, including residual pores, second phases and grain boundaries, is a key technique for improving the characteristics of the transparent ceramics. This paper discusses the current research issues related to synthesis methods and sintering processes for yttria-based transparent ceramics and $MgAl_2O_4$ spinel.

• Nuclear Engineering and Technology
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• v.48 no.3
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• pp.744-750
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• 2016

Uranium removal from uranium plant wastewater using zero-valent iron in an ultrasonic field was investigated. Batch experiments designed by the response surface methodology (RSM) were conducted to study the effects of pH, ultrasonic reaction time, and dosage of zero-valent iron on uranium removal efficiency. From the experimental data obtained in this work, it was found that the ultrasonic method employing zero-valent iron powder effectively removes uranium from uranium plant wastewater with a uranium concentration of $2,772.23{\mu}g/L$. The pH ranges widely from 3 to 7 in the ultrasonic field, and the prediction model obtained by the RSM has good agreement with the experimental results.

• Korean Journal of Pharmacognosy
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• v.45 no.2
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• pp.93-100
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• 2014

The Acer tegmentosum (3 kg) were extracted with boiled water and the freeze dried extract powder was partitioned with $CH_2Cl_2$, EtOAc, n-BuOH and $H_2O$, successively. From the EtOAc and n-BuOH fraction, six phenolic compounds were isolated through the silica gel, octadecyl silica gel and sephadex LH-20 column chromatography. On the basis of spectroscopic methods, such as $^1H$-NMR and $^{13}C$-NMR, and LC/MS, the chemical structures of the compounds as feniculin (1), avicularin (2), (+)-catechin (3), (-)-epicatechin (4), salidroside (5) and 6'-O-galloylsalidroside (6). In this study, compounds 1 and 2 have been first isolated from the A. tegmentosum. To provide insight into the effects of six compounds isolated from A. tegmentosum on inflammation, we investigated its effect on nitric oxide (NO) production in RAW 264.7 cells using lipopolysaccharide (LPS) stimulation. Compounds 1 and 6 slightly repressed NO production. Also, compounds 3 and 4 inhibited NO secretion with statistical significance. However, compounds 2 and 5 did not show any inhibitory effect on NO production.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.8
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• pp.641-646
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• 2011

Ga-doped ZnO-$SnO_2$ (ZSGO) films were deposited by rf magnetron sputtering and their structural and electrical properties were investigated. In order to fabricate the target for sputtering, the mixture of ZnO, $SnO_2$ (1:1 weight ratio) and $Ga_2O_3$ (3.0 wt%) powder was calcined at $800^{\circ}C$ for 1 h. The substrate temperature was varied from room temperature to $300^{\circ}C$. The crystallographic properties and the surface morphologies of the films were studied by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The optical transmittances of the films were measured and the optical energy band gaps were obtained from the absorption coefficients. The resistivity variation with substrate temperature was measured. Auger electron spectroscopy was employed to find the atomic ratio of Zn, Sn, Ga and O in the film deposited at room temperature. ZSGO films exhibited the optical transmittance in the visible region of more than 80% and resistivity higher than $10\;{\Omega}cm$.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2141-2152
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• 2024

Tungsten is the most promising plasma facing material for fusion reactors. Rolled W-Y₂(Zr)O₃ bulk material has been successfully produced in this study for future fusion engineering applications. The introduction of Zr is conducive to the refinement of the second phase particles. Nano-sized Y-Zr-O particles are observed in the powder and bulk samples. Related results show that the Y-Zr-O particle dispersion distribution improves the heat load resistance of W-Y₂(Zr)O₃ composite material. For four-point bend experiments in the same sampling direction, the DBTT of W-Y₂(Zr)O₃ composite materials is lower compared to the pure tungsten. For the same material, the DBTT of the material was selected for testing along the RD direction is lower compared to the material was selected for testing along the TD direction. Findings of this study provide suggestions for the subsequent industrial preparation of nanoscale particle-doped tungsten materials.

• Food Science and Preservation
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• v.13 no.4
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• pp.477-482
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• 2006

This study was carried out to evaluate the effect of the masting temperature on the phycochemical properties of the roasted Job's tears. Raw seeds were roasted for 20 min at 150, 170, 190, 210 or $230^{\circ}C$, were milled and extracted with hot water. The L and a values of the powder were sharply decreased or increased at the masting temperature of above $190^{\circ}C$, respectively. The b value was maximum at $190^{\circ}C$. Water absorption capacity of the powder and browning index of the extract were proportionally increasing with increasing the masting temperature. The pH of the extracts was decreased at the masting temperature of above $190^{\circ}C$. Total sugar content of the extract tended to be decreased until $170^{\circ}C$ and then be increased from $190^{\circ}C$. Content of phenolic compound of the extract was increased at the masting temperature of above $210^{\circ}C$. At the sensory evaluation of the extract, aroma and taste of samples masted at $170^{\circ}C$ and above $190^{\circ}C$, respectively were higher than those masted at the others. Overall acceptability of the extract was highest at $190^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.7
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• pp.853-859
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• 2006

This study was carried out to investigate the effect of egg shell calcium salt types and egg shell membrane on calcium metabolism in rats. Sprague-Dawley male rats, 4 weeks of age, were fed on free-calcium diets for 2 weeks after adjustment period. Rats weighing approximately $247{\pm}2.3g$ were divided into 6 groups and were fed on the experimental diets containing 0.2% calcium for 4 weeks. Experimental groups were as follows; {ES(M+)} (egg shell powder diet with egg shell membrane), {ES(M-)} (egg shell powder diet without egg shell membrane), {AC(M+)} (egg shell calcium acetate diet with egg shell membrance), {AC(M-)} (egg shell calcium acetate diet without eg shell membrane), {GC(M+)} (egg shell calcium glucuronate diet with egg shell membrane) and {GC(M-)} (egg shell calcium glucuronate diet without egg shell membrane). Bone length of femur was significantly different by the types (p<0.05) of egg shell calcium salts. Bone mineral density of femur showed the highest level in AC(M-) group. Calcium content of femur and calcium absorption rate were higher in egg shell calcium salt groups than in eg shell powder groups. Calcium absorption rate and retention were significantly different (p<0.05) among the types of eg shell calcium salts and were higher in the AC(M-) group than in the other groups. Alkaline phosphatase activity, parathyroid hormone and osteocalcin levels of serum showed no significant difference among the experimental groups. From the above results, it is concluded that bioavailability of calcium is higher in groups of egg shell calcium salts compared to those in egg shell powder, even though egg shell membrane has no effect on calcium metabolism. Thus, these findings suggest the possibility of using egg shell calcium salts as a functional food material related to calcium metabolism.

• Journal of the Korean Society of Radiology
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• v.9 no.6
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• pp.357-362
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• 2015

This study was to evaluate the usefulness through the comparison of patients group and healthy control group by acquiring a variety of functional parameters index from time-activity curves of salivary gland scan using 99mTc-pertechnetate. From December 2014 to February 2015, had the targets of 30 patients with dry mouth and 10 people in healthy control group underwent the salivary gland scan. After intravenous injection of 370 MBq of 99mTc-pertechnetate, Vitamin C powder stimulation was administerd orally at 20 min and then 10 minutes were taken scan. The method of quantitative analysis was as follows, the time-activity curve was drawn after the parotid gland and submandible gland were prescribed as a region of interest, a variety of function parameters index was obtained in each position of the curve, and the patients group and the control group were compared. As for the methods applied in comparison and measurement, uptake ratio (UR), time at maximum counts (Tmax), time at minimum counts (Tmin), maximum accumulation (MA), accumulation velocity, maximum secretion (MS), maximum stimulation secretion (MSS), and secretion velocity (SV) were used. In the comparison of functional parameters index of patient group and normal group, the healthy normal group showed significant difference compared to the patient group in all indices except for the minimum radioactivity time (Tmin), and also in terms of variation over time the normal group showed significant difference compared to the patient group (p<0.05). Consequently, it was considered that the quantitative analysis that used a variety of function parameters index would be useful for evaluating the function of the salivary glands of the patients with dry mouth as an objective and standardized information.

• Korean Journal of Materials Research
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• v.10 no.9
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• pp.642-647
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• 2000

Nanocrystalline NiAl alloy containing 36at.%Al was synthesized by mechanical alloying (MA). Synthesized powder was sintered by a pulse electric current sintering (PECS) facility. Effecting parameters on the phase transformation were discussed in terms of cooling rate and time spent on heat treatment. The behavior of phase transformation for sintered parts was examined by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) method. Microstructure was observed by scanning electron microscopy (SEM). Martensitic lattice parameter and volume fraction was calculated by direct comparison method in X-ray diffraction analysis.