• Korean Journal of Environmental Agriculture
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• v.34 no.4
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• pp.345-349
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• 2015

BACKGROUND: In this study, we have attempted to identify a urinary biomarker to assess chlorpyrifos exposure in farmers. The major metabolite and the excretion pathway of chlorpyrifos is 3,5,6-trichloro-2-pyridinol (TCP) in urine. Herein, we describe an adequate synthetic method for TCP hapten for measuring urinary TCP of farmers. METHODS AND RESULTS: First, TCP was prepared by spacer attachment through hydrolysis of thiophosphate ester from chlorpyrifos. After reaction with benzyl bromide, the TCP was transformed into 2,3,5-trichloro-6-benzyloxypyridine. Next, the chlorine in the 2 ^nd position of the pyridyl ring was substituted into 3-mercaptopropanoic acid spacer arm. Finally, the phenyl group attached to the 6 ^th position in pyridyl ring was removed for producing the targeted product, 3-(3,5-Dichloro-6-hydroxy-2-pyridyl) thiopropanoic acid. CONCLUSION: Henceforth, this TCP hapten would be used in developing immunoassay studies for the detection and quantitation of urinary TCP of farmers.

• Bulletin of the Korean Chemical Society
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• v.24 no.3
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• pp.334-338
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• 2003

A simple synthetic method for haptens of organophosphorus (OP) pesticides with a spacer arm (aminocarboxylic acid) attached at the pesticide thiophosphate group was developed and was applied to the synthesis of haptens for the OP fungicide tolclofos-methyl. Using the haptens, a selective enzyme-linked immunosorbent assay (ELISA) for tolclofos-methyl was developed. One of the haptens was coupled to BSA to use as an immunogen. Rabbits were immunized with this conjugate to obtain polyclonal antibodies to tolclofos-methyl. The antisera were screened against another hapten coupled to ovalbumin (OVA). Using the serum with highest specificity, an antigen-coated ELISA was developed, which showed an $IC_{50}$ of 160 ng/mL with the detection limit of 20 ng/mL. The antibodies showed negligible cross-reactivity with other OP pesticides. An antibody-coated ELISA was also developed, which showed an $IC_{50}$ of 410 ng/mL with a detection limit of 130 ng/mL.

• Korean journal of applied entomology
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• v.10 no.1
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• pp.13-22
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• 1971

This experiment was conducted to investigate the differences of the in vitro inhibitory effect of various organephobphorua insecticides on the chlinesterase from rice stem borer and those of the toxicity of them against the insect, with special references to the relationship between the cholinesterase inhibition and the toxicity. The results obtained were summarized as follows: Phosphate compounds shelved stronger inhibitory effect on the cholinesterase than thhiophosphate compounds, but was not stronger in toxicity than the latter. Diethoxy compounds were not always stronger than dimethoxy in cholinesterase inhibition and the toxicity of organophosphorus insecticides. The organophosphorus insecticides that inhibited strongly the cholinesterase were not always stronger in the toxicity.

• Korean Journal of Environmental Agriculture
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• v.1 no.1
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• pp.65-70
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• 1982

This experiment was conducted to see the effect of repeated application of IBP granular formulation(17%, 0,0-diisopropyl-S-benzyl thiophosphate) on the biodegradation of IBP and diazinon〔0,0-diethyl 0-(2-isopropyl-4-methyl-5-pyrimidinyl) phosphorothioate〕 in silt loam soil with 2.1% organic matter under flooded condition. The persistence of IBP in the soil was shortened by increasing the frequencies of application of the chemical. Enhanced degradation ability in the soil caused by repeated application of IBP was prolonged about 53 days, while the ability did not influence diazinon persistence in the soil. The half-lives of IBP in sterilized soil autoclaved at $121^{\circ}C$ for 30 minutes were about 3 times longer than those in viable soil, suggesting that microbial process was a major factor for IBP degradation in the soil. The total colony number of soil microbes showed little difference between the soils with and without repeated application of IBP. A possible concern of specific soil microorganisms on the pesticide degradation in soil was discussed.

• Journal of the Korean Ceramic Society
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• v.53 no.5
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• pp.568-573
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• 2016

We explore the crystalline structure and phase transition of lithium thiophosphate ($Li_7P_3S_{11}$) solid electrolyte using electron microscopy and X-ray diffraction. The glass-like $Li_7P_3S_{11}$ powder is prepared by the high-energy mechanical milling process. According to the energy dispersive X-ray spectroscopy (EDS) and selected area diffraction (SAD) analysis, the glass powder shows chemical homogeneity without noticeable contrast variation at any specific spot in the specimen and amorphous SAD ring patterns. Upon heating up to $260^{\circ}C$ the glass $Li_7P_3S_{11}$ powder becomes crystallized, clearly representing crystal plane diffraction contrast in the high-resolution transmission electron microscopy image. We further confirm that each diffraction spot precisely corresponds to the diffraction from a particular $Li_7P_3S_{11}$ crystallographic structure, which is also in good agreement with the previous X-ray diffraction results. We expect that the microscopic analysis with EDS and SAD patterns would permit a new approach to study in the atomic scale of other lithium ion conducting sulfides.

• Journal of the Korean Chemical Society
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• v.27 no.6
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• pp.449-456
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• 1983

The facile route of preparing S-2-(${\omega}$-aminoalkylamino) ethyl dihydrogen phosphorothioates, potential chemical radioprotectants, have been studied. Intermediate 3-(2-phthalimidoethyl)-2-oxazolidinone was prepared by a reaction of potassium phthalimide and 3-(2-bromoethyl)-2-oxazolidinone, which was obtained through the alkaline ring closure of a mixture of carbonate and 2,2'-dibromo diethylamine prepared from diethanolamine. This was converted to N-[2-(2-bromoethylamino)ethyl] phthalimide hydrobromide by 30% HBr(gas) in acetic acid and N-(2-bromoethyl)-1,2-ethanediamine dihydrobromide was obtained by reacting the hydrobromide with a solution of HBr-HOAc. N-(2-bromoethyl)-1,3-propanediamine dihydrobromide could be prepared through the Cortese treatment of 2-(3-aminopropylamino) ethanol, which was prepared by a reaction of 1,3-diaminopropane and 2-chloroethanol. These dihydrobromides were treated by sodium thiophosphate in DMF to result S-2-(${\omega}$-aminoalkylamino) ethyl dihydrogen phosphorothioates. The characteristics of each reaction path were discussed in regards to reaction conditions and overall yields and a facile route of preparing each derivative was proposed.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.4
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• pp.295-300
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• 2015

Purpose: The aim of this study was to evaluate the shear bond strength between Ni-Cr alloy and composite resin using universal adhesive systems coMPared to conventional method using metal primers. Materials and methods: For this study, a total of 120 cast commercial Ni-Cr alloy (Vera Bond 2V) disks were embedded in acrylic resin, and their surfaces were smoothed with silicon carbide papers and airborne-particle abrasion. Specimens of each metal were divided into 6 groups based on the combination of metal primers (Metal primer II, Alloy primer, Metal & Zirconia primer, MKZ primer) and universal adhesive systems (Single Bond Universal, All Bond Universal). All specimens were stored in distilled water at $37^{\circ}C$ for 24 hours. Shear bond strength testing was performed with a universal testing machine at a cross head speed of 1 m/min. Data (MPa) were analyzed using one-way ANOVA and the post hoc Tukey's multiple comparison test (${\alpha}$=.05). Results: There were significant differences between Single Bond Universal, All Bond Universal, Metal Primer II and Alloy Primer, MKZ Primer, Metal & Zirconia Primer (P<.001). Conclusion: Universal Adhesive system groups indicated high shear bond strength value bonded to Ni-Cr alloy than that of conventional system groups using primers except Metal Primer II. Within the limitations of this study, improvement of universal adhesive systems which can be applied to all types of restorations is recommended especially non-precious metal alloy. More research is needed to evaluate the effect of silane inclusion or exclusion in universal adhesive systems.

• Applied Biological Chemistry
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• v.7
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• pp.15-19
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• 1966

In order to investigate the stability of the major component of malathion E.C. product, dimethyl S-(1, 2-dicarboxyethoxyethyl) dithiophosphate, toward the quality of glasswares as container, the amount of extractable inorganic components, change of pH and decomposition of the major component of the product were examined during the storage in brown-colored bottles of 100 ml. volume from 3 different companies in comparison with that in a Pyrex flask. 1. Malathion E.C. product was put in three containers A,B and C, and any changes occurring in storage were analyzed at three intervals of 60, 120 and 240 days. 2. It was shown that the amounts of Si, Mg, K, Ca, and Na extracted during these periods of storage differed markedly depending on the qualify of container. Container A revealed ten times higher extraction of Na and Ca than container B and C in a 8-month period. 3. Three commercial containers revealed the shift of pH from 6.5 to alkaline reaction in the storage whereas the Pyrex flask did not show any detectable change. In particular, the pH in container A changed to 9.2 in 60 days and 9.9 in 240 days. 4. The decomposition of malathion was the greatest in container A which showed the decomposition of 7.37% in 240 days. On the other hand, 0.5% was decomposed in the Pyrex flask. 5. The decemposition of malathion had a high correlation with the change of pH of water· in the same container, $r^2$ being 0.899. From the above results, it is concluded that about 10% of malathion E.C. product is decomposed in a year due to the alkaline metallic salts extracted from the container when it is stored in glassware bottles of lower quality.