• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2466-2470
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• 2007

A new highly salicylate-selective PVC membrane electrode based on tripodal tris-thiourea derivatives, L1 and L2, as neutral carriers is described. The electrodes display an excellent potentiometric response to salicylate ions and an anti-Hofmeister selectivity sequence in the following order: Salicylate? > ClO4 ? > Benzoate? > I? >NO3? > NO2? > Maleate? > Acetate? > Lactate? > Fumarate?. It also exhibited a near-Nernstian potential in a linear range of 5.0 × 10?5 - 1.0 × 10?1 M with a detection limit of 9.0 × 10?5 mol/L and a slope of ?59.9 mV/decade at a pH of 7.0 in a saline buffer solution at 25 oC. The stability constant (log KS) of the anionsionophore complex was also determined at 25 oC by a conductometric titration in DMSO solution.

• Journal of the Korean Ceramic Society
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• v.31 no.5
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• pp.505-512
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• 1994

It has been reported that a biocement obtained by mixing CaO-SiO2-P2O5 glass powder and ammonium phosphate solution has biocompatibility as well as high strength. However, the compositional dependence on its hardening and hydroxyapatite formation phenomena has not been studied. Therefore, the main objective of this work is to study the effects of P2O5, MgO in CaO-SiO2 system glass on the hardening and hydroxyapatite formation. When more than 50 mole% of CaO containing CaO-SiO2 glasses was reacted with ammonium phosphate solution, CaNH4PO4.H2O crystal was formed, but the glass with less than 50 mol% of CaO formed (NH4)2HPO4 and NH4H2PO4 crystals which are derived from ammonium phosphate solution without reacting with the glasses. As the amount of P2O5 in CaO-SiO2-P2O5 glass system was increased, the formation of CaNH4PO4.H2O crystal was enhanced. When those hardened samples were reacted with tris-buffer solution, hydroxyapatite was obtained only for the sample with CaNH4PO4.H2O. While the substitution of MgO for CaO decreased the formation of CaNH4PO4.H2O crystal. MgNH4PO4.H2O crystla was formed in high MgO containing glass, which did not react with tris-buffer solution.

• Korean Journal of Veterinary Research
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• v.33 no.4
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• pp.623-632
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• 1993

This study was conducted to develop a sensitized latex-antigen for serodiagnosis of toxoplasmosis in animals. Tachyzoites of T gondii(RH-strain) harvested from mouse peritoneal cavity were purified through the filtraton of polycarbonate membrane(pore size, $3.0{{\mu}m}$, Costar Co.) and disrupted by ultrasonicator. The tachyzoite suspension was ultracentrifuged for 30 min at $60,000{\times}g(4{^{\circ}C})$ and the supernatant was used as a water-lysate antigen. Polystyrene latex particles of $0.8{{\mu}m}$ in diameter(Sigma) were used for the preparation of sensitized latex-antigen suspension. The several parameters including the preparation conditions, incubation buffer. serum dilution buffer and stability of agglutination reactions were evaluated and the results obtained were summarized as follows : 1. The antigen consisting of a water-lysate of T gondii tachyzoites was adsorbed onto polystyrene latex particles of $0.8{{\mu}m}$ in diameter by adding a latex suspension to an equal volume of diluted antigen solution and by incubating the mixture at $37{^{\circ}C}$ under different conditions. 2. The optimum incubation buffer used for the antigen sensitization was 0.1M Tris-HCl buffer(pH 8.0). 3. The optimum serum dilution buffer used for the latex agglutination test was 0.1M Tris-HCl-NaCl buffer(pH 7.4) containing 300 mM NaCl. But 0.1M Tris-HCl-NaCl buffer(pH 7.4) containing 300-600 mM NaCl, 0.5% BSA and 0.01% Tween-20 improved the agglutination pattems and cleared the background of microplate well without the effects on L.A titer. 4. The time required for antigen sensitization was 40 and 60 min in incubation buffer(pH 8.0) at $37{^{\circ}C}$. But the optimun time for antigen sensitization was min at $37{^{\circ}C}$. 5. The optimun quantity of antigen absorbed on latex particles for proper agglutination was the range of 20 to $32{\mu}g$ of latex particles. 6. The optimun concentration of the latex-antigen suspension for the proper agglutination reaction was determined as 0.2%(w/v). 7. The specificity, rapidity and simplicity of the latex-particle agglutination test suggested that it might be adaptable to large scale serum screening.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.393-404
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• 1992

The response properties of continuous automated system using an enzyme reactor for determination of urea were investigated. The enzyme reactor was constructed to packed-bed form which filled with nylon-6 beads (42∼48 mesh), which immobilized urease with glutaraldehyde, in teflon tube (2 mm I.D., 20 cm length). The system was composed of the enzyme reactor, gas dialyzer, and tublar PVC-nonactin membrane ammonium ion-selective electrode as an indicator electrode in serial order. The response characteristics of this system were as follows. That is, the concentration range of linear response, slope of linear response, detection limit, and conversion percentage were $5.5{\times}10^{-6}$∼$2.4{\times}10^{-3}M$, 57.8 mV/decade, $1.5{\times}10^{-6}$, and 80.8%, respectively. The optimum buffer and life time of urease reactor were 0.01M Tris-HCl buffer solution (pH 7.0∼7.8) and 0.01M phosphate buffer solution (pH 6.9∼7.5) and about 150 days, respectively. And the urease reactor had no interferences of the other physiological materials.

• KSBB Journal
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• v.16 no.2
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• pp.128-132
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• 2001

Cyclodextrin glucanotransferase (EC 2.4.1.19 : 1,4-$alpha$-glucan 4-$alpha$-D-(1,4-glucano) transferase, cyclizing; CGTase) was recovered by starch adsorption. The adsorption and desorption of CGTase to starch was studied as a function of pH, temperature, and starch type. The optimal pH, temperature, and starch for adsorption were, 8.0, $4^{circ}C$, and 1% (w/v) corn starch, respectively, per 205 U/mL enzyme activity in the presence of 25% (w/v) ammonium sulfate. The maximum adsorption ratio was 95%. On the other hand, the optimal pH, temperature, and starch type for desorption were 8.0 (tris-buffer), $50^{circ}C$, and oxidized starch, respectively. The maximum desorption ratio was 98% by tris-buffer solution at pH 8.0. The efficiency of adsorption and desorption were affected slightly by the removal of cells from the fermentation broth.

• Korean Journal of Clinical Laboratory Science
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• v.53 no.4
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• pp.326-332
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• 2021

Swabs are useful and common sampling tools in various research fields, such as medicine, ecology, biotechnology, forensic medicine, and pollutant monitoring systems. Collection reagents are one of the essential components in sampling. It is important to develop a sample collection kit and designate an appropriate storage temperature because samples need to be stored for a long time. The purpose of this study was to identify the effects of three collection reagents and three storage temperatures on the recovery of living bacteria without media. We selected Escherichia coli and Staphylococcus aureus as representative environmental bacteria. Distilled water (DW), phosphate buffered saline (PBS), and Tris-EDTA (TE) buffer were used as collection reagents and stored at 22℃, 4℃, and -70℃ after sampling. The results of using each collection reagent and storage temperature on the bacteria were compared using relative light units (RLU) and the number of colony forming units (CFU). When using -70℃ storage temperature and the TE buffer, the number of living bacteria and the RLU values remained constant. It is therefore recommended that the sample be stored at -70℃ immediately after collection and a TE buffer solution be used as the collection reagent.

• Analytical Science and Technology
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• v.11 no.5
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• pp.409-412
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• 1998

The analytical method to determine europium(III) ion in aqueous solution by fluorescence spectroscopy based upon the conformational change of calmodulin in the presence of the analyte has been studied. The fiber optic chemical sensor used in this study was constructed by entrapping a fluorescein-labeled calmodulin solution, EGTA, buffer solution at the common end of a bifurcated fiber optic bundle by means of a dialysis membrane. The calibration curve to determine europium(III) ion was obtained when concentration of calmodulin, concentration of EGTA, Tris-HCl buffer solution, pH, excitation wavelength and fluorescence wavelength were $5.0{\times}10^{-5}M$, 0.50 mM, 5.0 mM, 7.0, 495 nm and 520 nm, respectively. The detection limit was $1.0{\times}10^{-11}M$ and the working range of the calibration curve for the sensor was $1.0{\times}10^{-11}M{\sim}1.0{\times}10^{-9}M$. The response time was 15 minutes. For the determination of europium(III) ion by the present method, $Na^+$ and $K^+$ ions did not interfere but $Ca^{2+}$ ion seriously interfered.

• Korean Journal of Crystallography
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• v.16 no.2
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• pp.138-140
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• 2005

A new crystal of helminth glutathione S-transferase, 28 kDa isozyme from Clonorchis sinensis has been grown from a 20% PEG MME 550 solution containing 50 mM $CaCl_{2}$ in 0.1 M bis-Tris buffer (pH 6.5) in $2{\sim}3$ days. The crystals diffract to $3.0{\AA}$ resolution and belong to the orthorhombic space group $P2_{1}2_{1}2_{1}$ with cell parameters $a=62.58{\AA},\;b=69.92{\AA},\;and\;c=339.67{\AA}$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.13
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• pp.73-76
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• 1973

Protein spectra from 6 species of Gossypium were obtained by disc electraphoresis of seed extracts. Protein extracts were made by soaking 0.5g. of seed in 15ml of Tris-glycine buffer for 24 hours. Gels 24 hours. Gels were stained in 0.5% Amido Black solution for 1 hour, and destained in 7% acetic acid for 72 hours. Nine to 15 bands were visible in each gel. Homologies of Protein bands among the species were determined by migration velocity. Evidences obtained from electrophoretic separation of seed Protein were consistent with those from genetic, cytological, morphological and Phenogenetic methods regarding the origin of New World cultivated cottons. Possibility, however, does not exist to exclude Gossypium herbaceum from one of the Progenitors of New World cultivated cottons from electrophoretic evidences alone.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2315-2318
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• 2007

Epinephrine was determined using a lab-made chemiluminescence (CL) system with air pump. Luminolsodium IO4? chemiluminescence system was employed to produce the luminescence of epinephrine. In the reaction, epinephrine was oxidized to produce superoxide or singlet oxygen by periodate in alkaline solution, which enhanced CL of luminol. For optimization, various buffers, such as phosphate, borate, and tris, were studied in this experiment. Compared to NaOH, the phosphate and borate buffer showed better reproducibility with similar sensitivity. Small amount of sample, 22 μL, was required for a measurement. The limit of quantification for epinephrine was obtained to be ~10?9 g/mL after optimization.