• Journal of the Korean Magnetics Society
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• v.8 no.6
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• pp.350-356
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• 1998

$Y_{3-x}La_xFe_5O_{12}$ (x=0.0, 0.25, 0.5, 0.75, 1.0) powders and thin films were fabricated by a sol-gel method and their magnetic properties and crystal structure were investigated by using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and Mossbauer spectroscopy. XRD and Mossbauer spectroscopy measurements show that garnet powders annealed at 900 $^{\circ}C$ for 8 hours were single-phased and that thin films fired at 800 $^{\circ}C$ for 2 hours were crystallized without any preferred direction. X-ray diffraction patterns of $Y_{3-x}La_xFe_5O_{12}$ powders annealed at 1000 $^{\circ}C$ had only peaks of the garnet structure in case of x$\leq$0.75 but those of $Y_2LaFe_5O_{12}$ powders consisted of peaks from garnets and $LaFeO_3$. Mossbauer sepectra of garnet powders grown by the sol-gel method had a similar shape of those of powders grown by a conventional ceramic method. Grain sizes of garnet powders were 200~300 nm and the averaged surface roughness was 3.17 nm. Results of VSM measurements show the powders and thin films had soft magnetic properties and that the garnet powders had the largest saturation magnetization, 30 emu/g, and the lowest coercivity, 52 Oe.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.47 no.3
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• pp.227-235
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• 2021

In this study, we have prepared pure planar-type ZnO and calamine powder containing both ZnO and Fe₂O₃ components as a raw material for cosmetics with UV and blue band blocking functions. The planar-type ZnO ceramic powder having a high aspect ratio in the range of 20:1 to 50:1 was synthesized by precipitation method in a zinc acetate and sodium citrate mixed solution with the electrolyte obtained by power generation with a zinc-air battery. The content of Fe₂O₃ in the artificial calamine ceramic powder could be increased by increasing the amount of iron chloride solution added, and in this case, some of the blue region of visible light and ultraviolet light were remarkably absorbed. When potassium acetate was added, the decomposition of the Zn(OH)₄^2- anion in the solution was promoted to facilitate the growth of ZnO crystal in the form of a barrier wall in the vertical direction on the (0001) plane, which could increase UV absorption by providing more opportunities. By controlling the amount of iron chloride solution and potassium acetate solution added, the composition and shape of the thin film plate-shaped artificial calamine ceramic powder can be optimized, and when applied to cosmetic formulations, the light transmittance of the blue region can be greatly reduced.

• Korean Journal of Materials Research
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• v.29 no.7
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• pp.437-442
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• 2019

Green $BaSi_2O_2N_2:0.02Eu^{2+}$ phosphor is synthesized through a two-step solid state reaction method. The first firing is for crystallization, and the second firing is for reduction of $Eu^{3+}$ into $Eu^{2+}$ and growth of crystal grains. By thermal analysis, the three-time endothermic reaction is confirmed: pyrolysis reaction of $BaCO_3$ at $900^{\circ}C$ and phase transitions at $1,300^{\circ}C$ and $1,400^{\circ}C$. By structural analysis, it is confirmed that single phase [$BaSi_2O_2N_2$] is obtained with Cmcm space group of orthorhombic structure. After the first firing the morphology is rod-like type and, after the second firing, the morphology becomes round. Our phosphor shows a green emission with a peak position of 495 nm and a peak width of 32 nm due to the $4f^65d^1{\rightarrow}4f^7$ transition of $Eu^{2+}$ ion. An LED package (chip size $5.6{\times}3.0mm$) is fabricated with a mixture of our green $BaSi_2O_2N_2$, and yellow $Y_3Al_5O_{12}$ and red $Sr_2Si_5N_8$ phosphors. The color rendering index (90) is higher than that of the mixture without our green phosphor (82), which indicates that this is an excellent green candidate for white LEDs with a deluxe color rendering index.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.20-27
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• 2021

Effects of the etching treatment of SAPO-34 catalyst were investigated to improve the catalytic lifetime in DTO reaction. The aqueous NH3 solution was a more appropriate treatment agent which could control the degree of etching progress, compared to that of using a strong acid (HCl) or alkali (NaOH) solution. Therefore, the effect on characteristics and lifetime of SAPO-34 catalyst was observed using the treatment concentration and time of aqueous NH3 solution as variables. As the treatment concentration or time of aqueous NH3 solution increased, the growth of erosion was proceeded from the center of SAPO-34 crystal plane, and the acid site concentration and strength gradually decreased. Meanwhile, it was found that external surface area and mesopore volume of SAPO-34 catalyst increased at appropriate treatment conditions. When the treatment concentration and time were 0.05 M and 3 h, respectively, the lifetime of the treated SAPO-34 catalyst was the longest, and was significantly enhanced by ca. 36% (based on DME conversion of > 90%) compared to that of using the untreated catalyst. The model for the etching progress of SAPO-34 catalyst in a mild treatment process using aqueous NH3 solution was also proposed.

• Applied Chemistry for Engineering
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• v.34 no.6
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• pp.670-673
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• 2023

The biocompatibility of hydroxyapatite (HAP) has led to its application in various fields. To accomplish practical biological applications, such as drug/gene delivery, the colloidal stability of HAP in phosphate-buffered saline (PBS) is particularly important. In this study, we prepared a glycerol incorporated-HAP (Gly-HAP) by heating HAP in a glycerol environment at 200 ℃. To compare morphology and colloidal stability, HAP prepared at room temperature (RT-HAP) was thermally treated in water at 200 ℃ (H₂O-HAP). The heat treatment of HAP in both water and glycerol solutions results in an increase in the crystallinity of HAPs. Due to the low solubility of HAP in glycerol and the adsorption of glycerol on the HAP surface, crystal growth is limited. However, the heat-treated HAP under water increased in size by approximately four times compared to the initial crystallites. Compared to RT-HAP and H₂O-HAP, Gly-HAP shows improved colloidal stability in PBS, which originates from the adsorption of glycerol on the HAP surface that inhibits the agglomeration of individual HAP precipitates.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.50 no.1
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• pp.1-10
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• 2024

In this study, a quercetin benton gel (QUERPLEX) that stabilized quercetin was prepared using organo hectorite, and its efficacy was confirmed. In addition, a comparative study was conducted on the stability and effectiveness of applying this to sunscreen cosmetics. It was confirmed that QUERPLEX remained stable without showing crystal precipitation and growth for 4 weeks. As a result of measuring antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH), it showed antioxidant activity depending on the concentration, and showed a radical elimination ability of 70% or more at a concentration of 2,500 ppm or more, confirming a significant effect. Anti-inflammatory activity experiments using RAW 264.7 cells confirmed that NO production decreased in a concentration-dependent manner by reducing NO production by 8% at 25 ㎍/mL, 23% at 50 ㎍/mL, and 84% at 100 ㎍/mL. As a result of confirming the stability of the formulation according to the method of quercetin in the sunscreen formulation, the stability of the formulation was improved when quercetin was added directly to the formulation. It also improved the UV protection index on in vitro and in vivo, which is expected to have the potential as a component that can have a new boosting effect on UV protection. These results suggest that organo hectorite is very effective as a quercetin carrier and that it can be applied in cosmetic formulations by not only expressing the efficacy of quercetin but also bringing about additional effects.

• Korean Journal of Veterinary Research
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• v.15 no.2
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• pp.293-307
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• 1975

As it has been known recently that anisakis type larvae harbouring in marine fishes are a causal agent of zoonosis to human and probably to land living mammal animals, attention was focused on the study on the larvae in an aspect of epidemiology or epizootiology. The present work was conducted from 1966 to 1975 for i) survey on the harbouring status of anisakis type larvae in marine fishes of this country, ii) observation on the response to the experimental infestation of the larvae to the pigs, in the reason that they could well fetid raw fish viscera occasionally containing the larvae as a high protein source of swine food, and iii) observation on the larval resistance and response to vermicidal agents for the purpose of prevention of the larval infection to the mammal animals. The data obtained in the studies were summarized as follows: 1. In the survey on the status of larvae harbouring in main species of marine fishes of this country, 15 species, a total of 1,940 fishes, were observed and the result was summarized in table 2. Average number of larvae, in upper rank of 5 out of all 15 species of fishes, were as highest as 156 larvae ranging 74 to 450 in Pseudosciaena manchurica (chamjogi), 54.5 ranging 15 to 240 in Trichiurus haumela (kalchi), 35.6 ranging 8 to 112 in Trachurus japonica (junggengi), 30.6 ranging 4 to 65 in Parapristipama trilineatum (benjari) and 20.5 ranging 3 to 48 in Nibea argentata (boguchi) respectively. In morphological observation, size of the larvae in the fishes were varied, ranging from 2 to 32mm long, and a tendency to larger size and number of larvae in the fishes, which were wider sea migration, higher age and lager bodily size, was observed The favorite places harbouring the larvae in fishes were mainly around the intraperitoneal viscera such as mesentery, omentum, liver, pyloric suspensory, fat tissue and cloaca, and rarely in body muscles of fish. Fishes heartily infested with the larvae showed stunted growth decreased egg formation and severe damage of liver. 2. In the experimental infestation of the larvae to normal pigs, as illustrated in table 3, a group with large dose of larvae (a total of 1,800 larvae, 300 larvae Per dose, twice in a dart for 3 days) showed acute clinical syndrome terminatine death with a week course, whereas two groups with less dose of larvae (a total of 180~360 larvae, 10 larvae per dose, at 5 days interval for 70~180 days) showed subclinical syndrome with remarkably stunted growth as. much as approximately one half of body size in contest to the control pigs. In the pathological findings, a group with large dose of larvae showed macroscopically larvae penetrating to the gastric wall with severe gastroenteritis, and histopathologically various acute lesions caused by active larvae penetration into the wall of stomach and interstine, whereas two groups with less dose of larvae showed chronic lesions such as hypertrophy and verminous granulomatous swelling of gastric wall, suggesting strongly the possibility of natural infestation of larvae to swine. 3. In the resistance of the larvae to the chemical solutions, the larvae tolerated for 2 days in 15 percent solution of sodium chloride and acetic acid, and for 7 days in 70 percent solution of ethyl alcohol. In the resistance to the temperature, the larvae died within 1 second at $62^{\circ}C$ and tolerated for 24 hours at $-3^{\circ}C$, 12 hours $-5^{\circ}C$ respectively. 4. For the experiment on the vermicidal effect to larvae, general vermicidal drugs such as Neguvon, Combantrin, antimony Potassium, piperazine adipate and piperazine dihydrochloride, oxidizer such as potassium permanganate and potassium chlorate, and dyes such as gentian violet and crystal violet were used, and among them, as illustrated in table 6, potassium permanganate was proved as the best. In the successive test for the practical use of potassium permanganate, vermicidal effect in seawater solution of potassium permanganate and common-water solution of potassium permanganate were compared, and then retested by dipping the fish viscera including the larvae into the two different solutions of potassium permanganate. The result through these tests indicated that 0.01 percent common water and sea-water solution of potassium permanganate could be apparently recommended as a preventive vermicidal solution, having 90 to 100 percent vermicidal effect by dipping for 12 to 24 hours even though sea-water solution of potassium permanganate had a tendency to slightly less effect than the common-water solution of potassium permanganate (Table 8).

• Korean Journal of Mineralogy and Petrology
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• v.33 no.1
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• pp.53-64
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• 2020

The Samgwang deposit has been one of the largest deposits in Korea. The deposit consists of series of host rocks including Precambrian metasedimentary rocks and Jurassic Baegunsa formation, which unconformably overlies the Precambrian metasedimentary rocks. The deposit consists of eight lens-shaped quartz veins which filled fractures along fault zones in Precambrian metasedimentary rock, which feature suggest that it is an orogenic-type deposit. Laminated quartz veins are common in the deposit which contain minerals including quartz, ankerite, white mica, chlorite, apatite, rutile, arsenopyrite, sphalerite, chalcopyrite and galena. The structural formulars of white micas from laminated quartz vein and wallrock alteration are determined to be (K_1.02-0.82Na_0.02-0.00Ca_0.00)(Al_1.73-1.58Mg_0.26-0.16Fe_0.23-0.10Mn_0.00Ti_0.03-0.01Cr_0.01-0.00)(Si_3.35-3.22Al_0.79-0.65)O₁₀(OH)₂ and (K_0.75-0.67Na_0.01Ca_0.00) (Al_1.78-1.74Mg_0.16-0.15Fe_0.15-0.13Mn_0.00Ti_0.04-0.02Cr_0.01-0.00)(Si_3.33-3.26Al_0.74-0.67)O₁₀(OH)₂, respectively. It suggest that white mica from laminated quartz vein has higher interlayer cation (K+Na+Ca) and Fe+Mg+Mn+Ti content in octahedral site compared to the white mica from the wallrock alteration. Compositional variations in white mica from laminated quartz vein can be caused by phengitic or Tschermark substitution ((Al³⁺)^VI+(Al³⁺)^IV <-> (Fe²⁺ or Mg²⁺)^VI)+(Si⁴⁺)^IV) and (Fe³⁺)^VI <-> (Al³⁺)^VI substitution. Ankerite from laminated quartz vein has compositional variations of FeO and MgO contents along crystal growth direction. The geochemical and textural features suggest that laminated quartz vein from the Samgwang gold-silver deposit was formed during ductile shear stage, which is an important main gold-silver ore-forming event in orogeinc deposit.

• The Journal of the Petrological Society of Korea
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• v.6 no.3
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• pp.185-209
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• 1997

Granitic rocks in the Cheongsan area cosist of three plutons-Baegrog granodiorite, Cheongsan porphyritic granite, and two mica granite. Amphilboles from the Baegrog granodiorite belong to the calcic amphilbole group and show compositional variations from magnesio-hornblende in the core to actinolitic hornblende in the rim. Biotites from the three granites represent intermediate compositions between phlogopite and annite. Muscovites from the two mica granite are considered to be primary muscovite in terms of the occurrence and mineral chemistry. Each granitic rock reveals systematic variation of major oxide contents with $SiO_2$. Major oxide variation trends of the Baegrog granodiorite are fairly different from those of Cheongsan porphyritic granite and two mica granite. The latter two granitic rocks are also different with each other in variation trends for some oxides. Thus three granitic rocks in the Cheongsan area were solidifield from the independent magmas of chemically different, heterogeneous origin. The granitic rocks in the area show calc-alkaline nature. The whole rock geochemistry shows that the Baegrog granodiorite and Cheongsan porphyritic granite belong to metaluminous, I-type granite, whereas the two mica granite to peraluminous, I/S-type granite. The opaque mineral contents and magnetic susceptibility represent that the granitic rocks in the area are ilmenite-series granite, indicating that each magma was solidified under relatively reducing environment. The tectonic environment of the granitic activity in the area seems to have been active continental margin. Alkali feldspar megacryst in the Cheongsan porphyritic granite is considered to be magmatic, judging from the crystal size, shape, arrangement, and distribution pattern of inclusions. The petro-graphical characteristics of the Cheongsan porphyritic granite can be explained by two stage crystallization. Under the smaller degree of undercooling the alkali feldspar megacrysts rapidly grew owing to slow rate of nucleation and fast growth rate. At the larger degree of undercooling the nucleation rate and density drastically increased and the small crystals of the matrix were formed.

• The Journal of the Petrological Society of Korea
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• v.22 no.3
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• pp.219-233
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• 2013

Spherulitic rhyolite occur as part of ring dyke which showing a vertical flowage of $60^{\circ}{\sim}90^{\circ}$, of the Jangsan cauldron was studied. The spherulites range in diameter from a few millimeters to 2.8 centimeters or more, and average 5~10 millimeters. It belongs to radiated simple spherulite type. They consist of a core of moderate brown dense material encased by a thin crust, a few millimeters thick at most of white grey material. The spherulites frequently have a radiating fibrous structure, which are thought to have formed as a consequence of rapid mineral growth caused by very fast cooling of the dykes in shallow depth near the surface. EPMA examination of the concentric-zoned core of spherulites show that they are mainly composed of cryptocrystalline-fibrous intergrowth of silica minerals and alkali feldspars which have $SiO_2$ 82% or more, $Al_2O_3$ 7~10%, $Na_2O+K_2O$ less than 8%. The feldspar compositions of the spherulites lie essentially within the sanidine field. XRD examination show that spherulites are mainly composed of quartz, sanidine, albite with minor mica, kaolinite and chlorite. According to X-ray mapping, the spherulites are enriched in $SiO_2$ in the core and partly enriched $Na_2O$ or $K_2O$, $Al_2O_3$ in the shell that reflect in compositional zoning with increasing spherulitic devitrification. The feathery and non-equant crystal shapes of spherulites from rhyolite dyke of Jangsan cauldron suggest that they may have formed during the rapid cooling of dyke under the static state, or faster velocity of devitrification from glassy materials than movement velocity of the magma intrusion. The spherulitic rhyolite originated from high-silica(75.4~75.7 wt.%) rhyolite magma.