• Journal of Food Hygiene and Safety
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• v.20 no.3
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• pp.128-133
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• 2005

Ash of Anadarac tegillarca granosa shell was used for preparation of calcium lactate and calcium citrate, and improvement of their purity was carried out by using ammonium chloride process (ACP) and ammonium nitrate process (ACP). Purity of calcium lactate and calcium citrate made by the reaction of ash of Anadarac tegillarca granosa shell with lactic acid solution and with citric acid solution was 94.35-96.72 and $87.58-93.06\%$, respectively. However, purity of calcium lactate and calcium citrate prepared with purified calcium carbonate pre-purified from the ash of Anadarac fegiliarca granosa shell using ACP and ANP method was 99.53-100.34 and $99.32-99.88\%$, respectively. The purity of these calcium products were higher than those of calcium lactate and calcium citrate made with ash of Anadarac tegillarca granosa shell. Whiteness of calcium lactate and calcium citrate prepared with purified calcium carbonate pre-purified using ACP and ANP method was 94.8-98.5 and 99.4-101.5, respectively. Whiteness of these calcium products was higher than that of calcium lactate (91.8) and calcium citrate (92.9) made with the ash of Anadarac tegillarca granosa shell. Therefore, we estimated that calcium lactate and calcium citrate prepared with purified calcium carbonate using ACP and ANP method could be used potentially as a food additive for calcium supplement.

• Journal of the Korean Ceramic Society
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• v.33 no.9
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• pp.1003-1011
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• 1996

Hydroxyapatite powder was synthesized by a citrate method, . Char-like precursor composed of Ca8(HPO4)2(PO4)4.5H2O (OCP) and CaCo3 was found via viscous resin-like intermediate by heating the mixed aqueous solution of Ca(NO3)2.4H2O(NH4)2HPO4 and citric acid. Resulted powder was transformed into hydroxyapatite phase by firing over 120$0^{\circ}C$-135$0^{\circ}C$ for 4 hr using the powder calcined at 90$0^{\circ}C$ for 10 hr composed of mostly single hydroxyapatite phase. The sintered densities increased with firing temperature up to 130$0^{\circ}C$ but the highest relative density was about 94% of theoritical value. indicating the presence of closed pores. The maximum 96 MPa of flexural strength was obtained at 120$0^{\circ}C$ firing but the flexural strength showed lower values over the above sintering condition. Vitro test was performed by immersing of two jointed specimens in SBF for seven days and adhesion was observed between two specimens.

• Analytical Science and Technology
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• v.21 no.2
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• pp.135-142
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• 2008

Plasticizer and heavy metals in domestic PVC wallpaper manufactured in Korea after 2005 were analyzed to identify the contained quantity in comparison with the 2002 manufactured PVC wallpapers. Plasticizer of wallpapers was analyzed by the method KSM1991 which uses soxhlet extraction with n-hexane and GC/FID. Heavy metals were pre-treated with 0.07 mol/L hydrochloric acid (HCl) and analyzed by ICP/OES according to the EN 71-part 3 method. DEHP, DINP, DEP, acetyl tributyl citrate were identified from wallpaper. Contents of DEHP, DINP were 0.2~11.3%, 17.9~27.8% respectively in 6 wallpapers, DEP and acetyl tributyl citrate were 1.5%, 8.9% respectively in one wallpaper. Plasticizers have changed from DEHP that has possibility of hazards to DINP, DEP and acetyl tributyl citrate as compared with 2002. Heavy metals were detected under guide line from all of the wallpapers except fire-retardant wallpaper contain antimony. While PVC wallpaper was improved by use of various plasticizer, functional wallpapers such as fire-resistant wallpaper contain high antimony in this study.

• Journal of Environmental Science International
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• v.5 no.4
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• pp.535-544
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• 1996

In the development of Molten Carbonate Fuel Cell, one of the serious problems is the dissolution of cathode material. Therefore, the development of the alternative cathode which is stable in molten carbonate is needed. In this research, the licoo, was chosen as alternative cathode material. $LiCoO_2$ powder was synthesized by high temperature calcination method and by citrate sol-gel method. And its structure and physical iharacteristics were analyzed by XRD, 1 R, TCA and porosimeter. The conductivity and solubility of $LiCoO_2$ electrode were also measured. Homogeneous $LiCoO_2$ Powder was obtained by citrate sol-Rel method at 445$^{\circ}C$, however, obtained above 75$0^{\circ}C$ by high temperature calcination method. Homogeneous particle size distribution and fine powder were obtained by the citrate sol-Rel method. $LiCoO_2$ electrode showed higher electric conductivity ($1.7 $\Omega$^{-1}cm^{-1}$) than NiO (0.1 $\Omega$^{-9} cm^{-1}) at $650^{\circ}C$. The solubilities of $LiCoO_2$ electrode in electrolyte were varies 0.6 to 1.0 ppm during 200 hours. So, the solubilities of $LiCoO_2$ were much lower than that of NiO.

• The Korean Journal of Ceramics
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• v.5 no.3
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• pp.217-223
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• 1999

Proten-conductive $SrZr_{0.95} Y_{0.05} O_{2.975}$ powder was prepared by citrate gel method its characteristics and sinterability were investigated. Amorphous gel could be obtained from a citric acid solution that $SrCO_3$ and metal nitrates were dissolved. The initial decomposition of the gel proceeded up to $250^{\circ}C$, followed by combustion of its decomposition products in the temperature range from $250^{\circ}C$ to $500^{\circ}C$. A well-crystallized perovskite phase with a stoichiometric composition after calcination at $1000^{\circ}C$. Sintering green compacts of this powder for 6 h showed a considerable densification to start at $1200^{\circ}C$ and resulted in 86.8% and 96.5% relative densities at $1400^{\circ}C$ and $1600^{\circ}C$, respectively. Whereas, the powder compacts prepared by solid state reaction had much lower relative densities, 73% at $1400^{\circ}C$ and 92% at $1600^{\circ}C$.

• Korean Journal of Veterinary Service
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• v.22 no.4
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• pp.377-383
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• 1999

Polymorphonuclear (PMN) leucocytes are fundamental importance to the body's defense mechanism and play a major role in the local and systemic reactions to infectious disease. Investigation of the physiological and pathological role of the various leucocyte subtypes in host defence mechanisms is dependent upon the isolation of adequate numbers of viable, pure leucocyte fractions. This report describes the separate frequency of PMN leucocytes both from buffy coat layer and from packed RBC layer when bovine peripheral blood was treated with various anti-coagulants such as acid-citrate-dextrose(ACD), ethyldiaminetetraacetic acid(EDTA), sodium citrate and heparin. The separate frequencies of PMN leucocytes from buffy coat layer was 60.4$\pm$9.6%(heparin), 56.8$\pm$11.8%(sodium citrate), 30.6$\pm$14.1%(ACD) and 6.2$\pm$3.7%(EDTA), in order. Those from packed RBC layer monitored with EDTA, ACD, sodium citrate and heparin was 85.0$\pm$4.7%, 84.3$\pm$5.5%, 83.8$\pm$6.5% and 76.3$\pm$7.7%, respectively. The Ficoll-hypaque(FH) density gradient method was used to remove a small part of lymphocytes and/or monocytes from leucocytes in packed RBC layer. With the result that it increased separate frequency of PMN leucocytes from EDTA(89.9$\pm$2.4%), ACD(89.5$\pm$3.6%), and sodium citrate(83.6$\pm$10.3%) than heparin(68.4$\pm$13.9%). These results indicate that the use of EDTA and ACD as anticoagulant Is suitable for the separation of PMN leucocytes from bovine peripheral blood, and that the FH density gradient method is able to increase the separate frequency of PMN leucocytes from packed RBC layer.

• Journal of Microbiology
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• v.45 no.1
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• pp.48-52
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• 2007

A new procedure for the concentration of nonoviruses from water samples has been developed. This procedure (calcium flocculation-citrate dissolution method) uses the following steps: virus flocculation formed by treatment with 1 M $CaCl_2$ and 1 M $Na_2HPO_4$, virus release by sodium citrate dissolution (0.3 M Na citrate, pH 3.5), and virus re-concentration by ultrafiltration. When reverse transcription (RT)-PCR was performed after the procedure, the overall detection sensitivity for seeded noroviruses in a one liter drinking water sample was as low as 1 RT-PCR unit, which is equal to a $10^{-6}$ dilution of the virus sample. This approach showed at least a 5-fold-higher sensitivity than the current method with its three steps of adsorption-elution-concentration. The newly developed procedure was used to test different brands of bottled drinking water from China for putative contamination with noroviruses. A total of 144 samples were analyzed; all of the samples were negative for norovirus specific nucleic acids.

• Analytical Science and Technology
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• v.7 no.4
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• pp.493-504
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• 1994

The morphology and structure of precipitates of formed in Nb steels were investigated using SEM, TEM and XRD. The quantitative analysis of the precipitates was performed by ICP-AES. The potentiostatic etching method was employed as an extraction method using 10% AA-methanol and 15% Na-citrate electrolytes. The two selected potentials relative to SCE(Standard Calomel Electrode), -100mV in 10% AA-methanol solution and -250mV in 15% Na-citrate solution were found to be effective for the extraction. XRD analysis showed that composition of Nb carbonitride in Nb-steel(0.01% C-0.7% Nb-0.004N) was $NbC_{0.65}N_{0.2}$.

• Korean Journal of Materials Research
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• v.30 no.4
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• pp.204-210
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• 2020

ZnO thin films are of considerable interest because they can be customized by various coating technologies to have high electrical conductivity and high visible light transmittance. Therefore, ZnO thin films can be applied to various optoelectronic device applications such as transparent conducting thin films, solar cells and displays. In this study, ZnO rod and thin films are fabricated using aqueous chemical bath deposition (CBD), which is a low-cost method at low temperatures, and environmentally friendly. To investigate the structural, electrical and optical properties of ZnO for the presence of citrate ion, which can significantly affect crystal form of ZnO, various amounts of the citrate ion are added to the aqueous CBD ZnO reaction bath. As a result, ZnO crystals show a nanorod form without citrate, but a continuous thin film when citrate is above a certain concentration. In addition, as the citrate concentration increases, the electrical conductivity of the ZnO thin films increases, and is almost unchanged above a certain citrate concentration. Cu(In,Ga)Se₂ (CIGS) solar cell substrates are used to evaluate whether aqueous CBD ZnO thin films can be applicable to real devices. The performance of aqueous CBD ZnO thin films shows performance similar to that of a sputter-deposited ZnO:Al thin film as top transparent electrodes of CIGS solar cells.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.150-150
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• 2009

We prepared the Au-coated $TiO_2$ (Au/$TiO_2$) nanoparticles by deposition-precipitation (DP) method with and without bases (urea or NaOH) and investigated the effects of pH on the preparation of Au/$TiO_2$ nanoparticles for various kinds of bases. For the DP method without bases, the Au nanoparticles in the diameter of about 50 nm were generated in the solution by the reduction reaction with trisodium citrate and they did not deposit on the surface of $TiO_2$. For the DP method with bases, Au precursors deposited on the surface of $TiO_2$ and then reduced to the Au nanoparticles in the diameter of 4-5 nm on the surface of $TiO_2$ by the reaction with trisodium citrate.