• Journal of the Korean Magnetics Society
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• v.7 no.1
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• pp.7-12
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• 1997

Amorphous $Fe_{50}Zr_{50}$ alloy has been manufactured by mechanical alloying from pure elemental powders of Fe and Zr in conventional ball mill under an Ar atmosphere. Structure and magnetic properties of the amorphous phase were studied by transmission electron microscopy and SQUID magnetometry. Selected area diffraction patterns taken from the mechanically alloyed powders showed two halo rings, indicating coexistence of Fe rich and Zr rich amorphous phases in mechanically alloyed powder. Curie temperature of the Fe rich amorphous phase, measured by Arrot plot, was 195 K. Fe content in the ferromagnetic amorphous phase, estimated from the Curie temperature, was about 65 at%. Spin wave stiffness constant of $Fe_{50} Zr_{50}$ alloys processed for 100 and 200 hrs were 52.2 and 63.8 meV, respectively. The higher spin wave stiffness constant in 200 hrs milled powders may arise from the precipitation of $\alpha$-Fe by partial crystallization of amorphous phase.

• Korean Journal of Materials Research
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• v.25 no.8
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• pp.370-375
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• 2015

In this study, to confirm the effect of alloying elements on the phase transformation and conditions of the friction stir process, we processed two materials, SS400 and SM45C steels, by a friction stir process (FSP) under various conditions. We analyzed the mechanical properties and microstructure of the friction stir processed zone of SS400 and SM45C steels processed under 400RPM - 100mm/min conditions. We detected no macro (tunnel defect) or micro (void, micro crack) defects in the specimens. The grain refinement in the specimens occurred by dynamic recrystallization and stirring. The microstructure at the friction stir processed zone of the SS400 specimen consisted of an ${\alpha}$-phase. On the other hand, the microstructure at the friction stir processed zone of the SM45 specimen consisted of an ${\alpha}$-phase, $Fe_3C$ and martensite due to a high cooling rate and high carbon content. Furthermore, the hardness and impact absorption energy of the friction stir processed zone were higher than those of base metals. The hardness and impact absorption energy of FSPed SM45C were higher than that of FSPed SS400. Our results confirmed the effect of alloying elements on the phase transformation and mechanical properties of the friction stir processed zone.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.1
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• pp.49-59
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• 1997

This study was performed to analyze the purity of technical grade ${\alpha}$-naphthylamine, to establish optimal analytical condition of ${\alpha}$-naphthylamine in urine and to determine the urine sample of workers exposed to ${\alpha}$-naphthylamine. The purity of technical grade ${\alpha}$-naphthylamine were $96.5{\pm}2.38%$, $94.1{\pm}0.97%$, $97.0{\pm}0.02%$ by gas chromatography-mass selective detector. To analyze ${\alpha}$-naphthylamine in urine, high performance liquid chromatography-electrochemical detector and gas chromatography-electron capture detector operating conditions have been optimized by preliminary expriment. In high performance liquid chromatography-electrochemical detector, the mobile phase was consisted of acetonitrile(35%) and water(65%), and the flow rate was maintained at 1.0ml per minute. Optimal detective condition was 9.0V(10nA/V) of electrochemical detector. The recovery of sep-pak treatment method was highly estimated as pretreatment of ${\alpha}$-naphthylamine in urine. The free amine was isolated by gas chromatography-electron capture detector after basic hydrosis, sep-pak treatment, toluene elution and HFBA(heptafluoro-butyric anhydride) derivatization of urine. The recovery of ${\alpha}$-naphthylamine in urine was $98.73{\pm}3.29%$ by gas chromatography-electron capture detector. The sensitivity was more higher than that of high performance liquid chromatography-electrochemical detector. Urinary ${\alpha}$-naphthylamine was detected in only one worker among nine workers. The level of ${\alpha}$-naphthylamine in urine was 6.42 ng/ml.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.3
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• pp.280-285
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• 1999

$\alpha$-$Fe_2O_3$ thin film gas sensors were deposited at various temperature by CVD method. Polycrystalline $\alpha$-$Fe_2O_3$ thin films were deposited at $175^{\circ}C$ and $200^{\circ}C$. $\gamma$-$\alpha$-$Fe_2O_3$ phase was obtained when the deposition temperature was higher than $250^{\circ}C$. The crystallite size of $\alpha$-$Fe_2O_3$ was affected by the deposition and annealing temperature. The specimen deposited at $175^{\circ}C$ showed maximum sensitivity. In this condition, the sensitivity of $\alpha$-$Fe_2O_3$ thin film for NO gas (at 250 ppm) was 3.2 and response time (at 100ppm) was 12 second.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.7
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• pp.1064-1070
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• 2005

Tocopherol and tocotrienol contents of commonly consumed foods in Korea were determined by saponification or direct solvent extraction followed by normal phase liquid chromatography. All samples were locally obtained in the year of 2002 and 2003. The study included 13 meats, 15 fishes and shellfishes, 4 seaweeds, 7 mushrooms, 19 milk and milk products, 6 legumes, 12 nuts, 17 processed foods and 17 Korean traditional foods. All of the vitamin E isomers were quantitated and the results were expressed as $\alpha-tocopherol$ equivalent $(\alpha-TE)$. The relatively higher amount of vitamin E was found in beef boiled in soy, dried squid, toasted seaweed, milk powder, soritae, sunflower seeds, ramyon (instant noodle), and kochujang from meats, fishes, seaweeds, milk products, legumes, processed foods, and traditional foods, respectively. This study provided reliable vitamin E data in commonly consumed foods in Korea for the nutritional information and food composition database.

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1222-1228
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• 1999

The effects of Sn and Nb content on the characteristics of ${\beta}$ to ${\alpha}$ phase transformation for Zr were studied by optical microscopy and transmission electron microscopy. The basketweave structures consisted of fine ${\alpha}$-laths were shown in all the air-cooled specimens. As the Nb content increased, the ${\beta}{\to}{\alpha}$+${\beta}$ transformation temperature decreased thus allowing the width of ${\alpha}$-lath, however, did not change with Sn content. While water-quenched pure Zr and Zr-xSn alloys were found to be mailny slipped martensite, water-quenched Zr-xNb alloys showed predominantly a twinned martensite. The transition of slipped martensite to twinned martensite was contributed to the decrease of Ms temperature.

• Applied Biological Chemistry
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• v.37 no.3
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• pp.203-209
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• 1994

When $^{14}C-{\alpha}-endosulfan$ was incubated with carp liver, kidney and gut preparations, it was metabolized to water soluble and organosoluble metabolites. In an in vitro test, endosulfan was converted to endosulfan ${\alpha}-hydroxyether$ (EHE), endosulfan alcohol (EA) and endosulfan ether (EE). The addition of NADPH resulted in rapid conversion of endosulfan to the metabolites in 105,000 g soluble fraction and microsomes. However, the rate of metabolism of endosulfan in liver, kidney and gut supplemented with NADPH as a cofactor was higher in the 105,000 g soluble fraction than that in the microsomes of carp under incubation conditions. The enzymes probably involved in the metabolism of endosulfan include the glutathione S-transferase (GST) and the mixed function oxidases (MFO), based on the evidence that addition of either GSH or NADPH increased the degradation of endosulfan.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.573-579
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• 1994

1-O-oleoyl glycerol, 2-O-oleoyl myo-inositol and methyl 2-O-oleoyl-${\alpha}$-D-glucopyranoside were used as surfactants in this study. The solution properties and solubilization process of those nonionic surfactants were examined by the phase equilibria. As a result of this study, we have found that phase behavior of two component systems of surfactants/$H_2O$/cyclohexane depends on temperature respectively. The three phase regions of three component systems appeared in the temperature range of $27^{\circ}C{\sim}32^{\circ}C$, $36^{\circ}C{\sim}45^{\circ}C$ and $38^{\circ}C{\sim}52^{\circ}C$ and solubilization of water and oil was high in those three phase ranged As the temperature was varied in the two component systems, liquid crystals of hexagonal were observed to in the case of 1-O-oleoyl glycerol, and liquid crystal of lamella types were observed in the case of 2-O-oleoyl myo-inositol and methyl 2-O-oleoyl-${\alpha}$-D-glucopyranoside.

• Journal of the Korean Magnetics Society
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• v.1 no.1
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• pp.25-29
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• 1991

It has been found that the as-quenched ribbons of $Sm_{x}Fe_{100-x-y}Ti_{y}(3.8{\leq}x{\leq}11.5,\;3.8{\leq}y{\leq}19.2)$ are composed of metastable $TbCu_{7}-type$ structure, ${\alpha}-(Fe,\;Ti),\;Fe_{2}Ti$ and an unknown phase accompanying strong diffraction line at $d=2.14{\AA}$. The metastable $TbCu_{7}-type$ phase, which was formed by rapid quenching, did not transform fully to the stable phases after annealing at $850^{\circ}C$ for 45 minutes except the one existed in $SmFe_{11}Ti$ melt-spun ribbon. The $SmFe_{11}Ti$ melt-spun ribbon, annealed at $850^{\circ}C$ for 45 minutes in vacuum, was found to be composed of $ThMn_{12}$. $\alpha$-(Fe, Ti) and $Fe_{2}Ti$ phases. The formation of $\alpha$-(Fe, Ti) and $Fe_{2}Ti$ phases in this melt-spun ribbon was due to the evaporation of Sm atoms during the high temperature annealing. The atomic ratios for the surface and the inside of $SmFe_{11}Ti$ melt-spun ribbon annealed in vacuum were $SmFe_{25.8}Ti_{2.6}$ and $SmFe_{11.7}Ti_{1.0}$ respectively. It is thought to be that much of $\alpha$-(Fe, Ti) and $Fe_{2}Ti$ phases exist on the surface of ribbon.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.6
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• pp.788-794
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• 2013

Mastitis set apart as clinical and sub clinical is a disease complex of dairy cattle, with sub clinical being the most important economically. Of late, laboratories showed interest in developing biochemical markers to diagnose sub clinical mastitis (SCM) in herds. Many workers reported noteworthy alternation of acute phase proteins (APPs) and nitric oxide, (measured as nitrate+nitrite = NOx) in milk due to intra-mammary inflammation. But, the literature on validation of these parameters as indicators of SCM, particularly in riverine milch buffalo (Bubalus bubalis) milk is inadequate. Hence, the present study focused on comparing several APPs viz. ${\alpha}_1$-anti trypsin, ${\alpha}_1$-acid glycoprotein, fibrinogen and NOx as indicators of SCM in buffalo milk. These components in milk were estimated using standardized analytical protocols. Somatic cell count (SCC) was done microscopically. Microbial culture was done on 5% ovine blood agar. Of the 776 buffaloes (3,096 quarters) sampled, only 347 buffaloes comprising 496 quarters were found positive for SCM i.e. milk culture showed growth in blood agar with $SCC{\geq}2{\times}10^5$ cells/ml of milk. The cultural examination revealed Gram positive bacteria as the most prevalent etiological agent. It was observed that ${\alpha}_1$-anti trypsin and NOx had a highly significant (p<0.01) increase in SCM milk, whereas, the increase of ${\alpha}_1$-acid glycoprotein in infected milk was significant (p<0.05). Fibrinogen was below detection level in both healthy and SCM milk. The percent sensitivity, specificity and accuracy, predictive values and likelihood ratios were calculated taking bacterial culture examination and $SCC{\geq}2{\times}10^5$ cells/ml of milk as the benchmark. Udder profile correlation coefficient was also used. Allowing for statistical and epidemiological analysis, it was concluded that ${\alpha}_1$-anti trypsin indicates SCM irrespective of etiology, whereas ${\alpha}_1$-acid glycoprotein better diagnosed SCM caused by gram positive bacteria. NOx did not prove to be a good indicator of SCM. It is recommended measuring both ${\alpha}_1$-anti trypsin and ${\alpha}_1$-acid glycoprotein in milk to diagnose SCM in buffalo irrespective of etiology.