• 한국산업보건학회지
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• 제8권1호
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• pp.115-123
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• 1998

Vinyl chloride monomer exists as gas phase at normal temperature and reacts with oxygen and strong oxidant in the air to form oxidized materials. Because of being easily synthesized, it is used as a main source at the synthetic reaction process of PVC synthesis factories. Ministry of Labor regulates its usage as a carcinogen and its exposure level as 1 ppm. But the amount of VCM production in PVC and VCM production process hasn't been exactly estimated. In addition, facilities of this factory are located in outdoor. Therefore, this study was designed to investigate effects of temperature on breakthrough of charcoal tube at a fixed concentration and temperature during VCM sampling based on NIOSH and OSHA methods which were used as methods of occupational environment measuring and analysis. During the sampling of VCM, methods of OSHA and NIOSH require flow rate of 0.05 lpm and sampling volume of $3{\ell}$, $5{\ell}$ respectively, at this time carbon molecular sieve tube and coconut shell charcoal tube are used to observe the breakthrough along with concentration and temperature. As a result, significant difference between average adsorbed amounts of OSHA methods but that of NIOSH methods cannot be found. NIOSH method is likely to be effected by high temperature and normal temperature in high concentration. Breakthrough is not found in the method of OSHA at different conditions of temperature and concentration. As the result of this study we could verify that breakthrough occurred in the process of sampling VCM with NIOSH methods. Therefor in summer time, breakthrough should be considered and research on the breakthrough volume should be done. It is considered the research about the specificity of the coconut shell charcoal and carbon molecular sieve sorbent should be done when sampling VCM in comming days.

• 한국임상수의학회지
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• 제22권4호
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• pp.322-327
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• 2005

보체의존성 세포독성반응(CDC)을 이용한 DLA class I교차 반응의 실험방법을 정립함으로써 개의 동종 신장이식 후 초기에 발생되는 초급성 거부반응을 억제하는데 응용하고자 븐 실험을 실시하였다. 체중(약 5kg)과 연령(약 1년령)이 유사한 잡종견을 대상으로 적혈구 교차 반응을 실시하여 상호 음성인 7마리를 실험에 사용하였다. 혈액형이 동일한 개체를 대상으로 CDC검사를 실시하였으며, Anti-dog serum, Hank's balanced salt solution (HBSS), 그리고 자가 혈청을 각각 양성 음성 그리고 자가 대조 혈청으로 이용하였다. Class I보체와 반응시킨 후 에오신으로 염색하여 고정한 다음 위상차 현미경 100배율에서 조사하였다. 국제 Cytotoxicity scoring system에 의하려 죽은 세포가 $20\%$ 이상이면 양성으로 평가하였다. CDC 결과 동일 혈액형 군에서 상호 음성이 나온 경우를 대상으로 상호 동종이식을 실시하여 초급성 거부반응의 발생 정도를 평가하였다. 혈액형이 1.2 B인 4두 중 1두는 자가항체를 가지고 있었다. CDC 결과 동일 혈액형 군에서 각각 1쌍이 상호 음성을 나타내었고, 혈액형이 다른 1쌍에서도 상호 음성이 관찰되었다. 혈액형이 동일하고 CDC음성인 2쌍 4두를 대상으로 상호 신장 이식을 한 결과 4마리 모두 초급성 거부반응이 나타나지 않았다. 이 실험에서 확립한 DLA교차 방법은 동종 이식에서 초급성 거부반응을 억제하는데 효과적인 방법이며, 향후 개의 동종 장기 이식에서 조직적합성 평가를 위해 응용될 수 있을 것이라 사료된다.

• 한국동물위생학회지
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• 제42권4호
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• pp.289-296
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• 2019

A novel rapid procedure with liquid chromatography tandem mass spectrometry (LC-MS/MS) detection has been developed by changing various conditions including sample preparation such as QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) methodology. This work has been involved the optimization and validation of detection method for fluoroquinolones which are widespread used in livestock especially in the chicken. Five grams of homogenized chicken muscle were extracted with QuEChERS EN and acetonitrile containing 5% formic acid and cleaned with anhydrous magnesium sulfate and C₁₈ sorbent. The separation was performed on Acquity UPLC HSS T3 (2.1 mm×100 mm, 1.8 ㎛) column. The mobile phase A and B were composed of water containing 0.1% formic acid and acetonitrile containing 0.1% formic acid, respectively. Flow rate was 0.25 mL/min and column temperate was 40℃. LC-MS/MS with multiple reaction monitoring has been optimized for ten fluoroquinolones (ciprofloxacin, danofloxacin, difloxacin, enrofloxacin, marbofloxacin, norfloxacin, ofloxacin, orbifloxacin, pefloxacin and sarafloxacin). The method developed in this study has been presented good linearity with correlation coefficient (R²) of 0.9971~0.9998. LOD and LOQ values ranged from 0.09 to 0.76 ppb and from 0.26 to 2.29 ppb, respectively. The average recoveries were from 77.46 to 111.83% at spiked levels of 10.0 and 20.0 ㎍/kg. Relative standard deviation (%) ranged 1.28~11.90% on intra-day and 3.10~8.38 % on inter-day, respectively. This analysis method was applicable to the livestock residue laboratories and was expected to be satisfactory for the residue surveillance system.

• 한국식품위생안전성학회지
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• 제31권3호
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• pp.194-200
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• 2016

돼지고기 중 5종의 곰팡이독소(아플라톡신 $B_1$, $B_2$, $G_1$, $G_2$ 및 오크라톡신 A)를 분석하기 위해 0.1% 개미산을 함유한 50% 아세토니트릴용액으로 추출한 후 고체상추출칼럼을 이용하여 정제하고, LC-MS/MS로 동시 정량할 수 있는 시험법을 마련하였다. 분석조건으로 측정한 5종의 곰팡이독소 matrix-matched 표준곡선식에서 모두 상관계수 0.998이상의 상관관계를 나타내었다. 5종의 곰팡이독소 2배의 정량한계에서 10배의 정량한계로 첨가한 시료에서 평균 회수율은 72.1~109.9%로 실험 결과들이 EU 가이드라인에서 제시하는 유효성 확인을 위한 기준을 만족함으로써 시험법의 신뢰성을 확보할 수 있었다. 충청지역 유통되고 있은 돼지고기 20건에 대한 총아플라톡신 및 오크라톡신A에 대한 오염도 조사결과 정량한계 미만으로 조사되었다.

• 한국결정성장학회지
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• 제4권2호
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• pp.139-147
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• 1994

올소인산엽 결정의 육성을 수열법에 의해 행하였으며,육성결정의 성질은 X선 회절,Vickers 경도계 등을 이용하여 조사하였다. $AIPO_4$와 $GaPO_4$의 출발원료는 $AI_2O_3$또는 $Ga_2O_3$와 $NH_4H_2PO_4$의 혼합물을 고상반응시킨 뒤 얻어진 반응물을 수열처리하여 단상으로 제조하였다. 올소인산염 결정의 육성에 있어 큰 성장속도를 나타내는 수열조건은 다음과 같았다. 즉,$AIPO_4$ 결정: 온도범위, $170$~$200^{\circ}C$; 온도차, $15$~$20^{\circ}C;$수열용매, 4몰 HCI용액, $GaPO_4$결정: 온도범위, 210~$240^{\circ}C;$ 온도차, $25$~$30^{\circ}C; $ 수열용매,4몰 HCI용액이었다. 육성결정의 형태는 저온에서(1010),(1011),(0111)면이 발달하는 경향을 보였으나 육성온도가 증가함에 따라(0001)면이 잘 발달하였다. 한편, 올소인삼염 결정 $(AIPO_4/GaPO_4)$의 성질은 다음과 같았다. 즉, 격자정수$(Nm^2)$;a=0.494,c=1.094/a=0.490,1.105, 밀도 $(gcm^{-3}); 2.62/3.56$,경도$(Nm^2);1.02{\times}10^1^0/7.06{\times}10^9, $굴절율; $n_e= 1.529{\pm}0,003, n_e= 1.529{\pm}0,003/ n_e= 1.611{\pm}0,006,n_e= 1.599{\pm}0,006$,복굴절율;${\pm}0.01$ / $ {\pm}0.012$, 유전율 $(Fm^-1); 6/7$이었다.

• 한국세라믹학회지
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• 제25권3호
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• pp.207-216
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• 1988

$C_3S$의 생성반응과 특성에 미치는 $SO_3$의 영향을 클린커중에서의 반응물질의 확산, $C_3S$의 결정크기 변화 및 조성변화 등을 통하여 규명하였다. 2.0% 미만의 $SO_3$를 첨가하였을 때 $C_3S$의 생성은 양호하였으나 2.0%이상이 첨가되면 오히려 $C_3S$의 생성이 억제되었다. 융액내로의 Si성분의 확산계수는 약 $3.6~4.2{\times}10^{-7}Cm^2$/sec이었으며 $SO_3$의 함량이 증가함에 따라 미소하게 감소하였으나 크게 영향을 받지 않는 것으로 보인다. 1.0% 이상의 $SO_3$를 첨가한 클린커에서 생성된 $C_3S$의 크기는 점점 거대해지는 경향이 있었다. 또한 클린커 조성에 $SO_3$의 양이 증가할수록 융액 조성중의 CaS는 감소하고 $SiO_2$는 증가하였으며 따라서 $C_3S$의 생성이 저하하는 것은 CaO 성분이 융액내로의 용해 및 물질이동이 저해되기 때문이라 생각된다.

• 한국세라믹학회지
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• 제50권3호
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• pp.231-237
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• 2013

Thermodynamic modeling of the $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ complex ferrite system has been adopted as a rational approach to establish routes to better synthesis conditions for pure phase $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ complex ferrite. Quantitative analysis of the different reaction equilibria involved in the precipitation of $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ from aqueous solutions has been used to determine the optimum synthesis conditions. The spinel ferrites, such as magnetite and substitutes for magnetite, with the general formula $MFe_2O_4$, where M= $Fe^{2+}$, $Co^{2+}$, and $Ni^{2+}$ are prepared by coprecipitation of $Fe^{3+}$ and $M^{2+}$ ions with a stoichiometry of $M^{2+}/Fe^{3+}$= 0.5. The average particle size of the as synthesized $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$, measured by transmission electron microscopy (TEM), is 14.2 nm, with a standard deviation of 3.5 nm the size when calculated using X-ray diffraction (XRD) is 16 nm. When $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ ferrite is annealed at elevated temperature, larger grains are formed by the necking and mass transport between the $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ ferrite nanoparticles. Thus, the grain sizes of the $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ gradually increase as heat treatment temperature increases. Based on the results of Thermogravimetric Analysis (TGA) and Differential Scanning Calorimeter (DSC) analysis, it is found that the hydroxyl groups on the surface of the as synthesized ferrite nanoparticles finally decompose to $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ crystal with heat treatment. The results of XRD and TEM confirmed the nanoscale dimensions and spinel structure of the samples.

• 한국전기전자재료학회논문지
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• 제28권8호
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• pp.531-538
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• 2015

This study examined the size and shape of the nano-silver particle through the analysis of electrical resistance when synthesizing nano-sized silver by using the chemical liquid reduction. Changes in particle behaviors formed according to the changes in electronic characteristics by electric resistance in each time period in the beginning of reduction reaction in a course of synthesizing the nano-silver particle formation were studied. In addition, analysis was conducted on particle behaviors according to the changes in concentration of $AgNO_3$ and in temperature at the time of reduction and nucleation and growth course when synthesizing the particles based on the particle behaviors were also examined. As the concentration of $AgNO_3$ increased, the same amount of resistance of approximately $5{\Omega}$ was increased in terms of initial electronic resistance. Furthermore, according to the result of formation of nuclear growth graph and estimation of slope based on estimated resistance, slops of $6.25{\times}10^{-3}$, $2.89{\times}10^{-3}$, and $1.85{\times}10^{-3}$ were derived from the concentrations of 0.01 M, 0.05 M, and 0.1 M, respectively. As the concentration of $AgNO_3$ increased, the more it was dominantly influenced by the nuclear growth areas in the initial phase of reduction leading to increase the size and cohesion of particles. At the time of reduction of nano-silver particle, the increases of initial resistance were $4{\Omega}$, $4.2{\Omega}$, $5{\Omega}$, and $5.3{\Omega}$, respectively as the temperature increased. As the temperature was increased into $23^{\circ}C$, $40^{\circ}C$, $60^{\circ}C$, and $80^{\circ}C$, slopes were formed as $4.54{\times}10^{-3}$, $4.65{\times}10^{-3}$, $5.13{\times}10^{-3}$, and $5.42{\times}10^{-3}$ respectively. As the temperature increased, the particles became minute due to the increase of nuclear growth area in the particle in initial period of reduction.

• Asian Pacific Journal of Cancer Prevention
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• 제15권8호
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• pp.3581-3586
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• 2014

Aim: To investigate the effects of tetramethypyrazine (TMP) on proliferation and apoptosis of the human gastric carcinoma cell line 7901 and its possible mechanism of action. Methods: The viability of TMP-treated 7901 cells was measured with a 3-(4, 5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT) and cell apoptosis was analyzed by flow cytometry. The distribution of cells in different phases of cell cycle after exposure of TMPs was analyzed with flow cytometry. To investigate the molecular mechanisms of TMP-mediated apoptosis, the expression of NF-${\kappa}Bp65$, cyclinD1 and p16 in SGC-7901 cells was analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and western blotting. Results: TMP inhibited the proliferation of human gastric carcinoma cell line 7901 in dose and time dependent manners. Cell growth was suppressed by TMP at different concentrations (0.25, 0.5, 1.0, 2.0 mg/ml), the inhibition rate is 0.46%, 4.36%, 14.8%, 76.1% (48h) and 15.5%, 18.5%, 41.2%, 89.8% (72h) respectively. When the concentration of TMPs was 2.0mg/ml, G1-phase arrest in the SGC-7901 cells was significant based on the data for cell cycle distribution. RT-PCR demonstrated that NF-${\kappa}Bp65$ and cyclin D1 mRNA expression was significantly down-regulated in 7901 cells treated with 2.0 mg/ml TMP for 72h (p<0.05), while the p16 mRNA level was up-regulated (p<0.05). The protein expression of NF-${\kappa}Bp65$ and cyclin D1 decreased gradually with the increase in TMP concentration, compared with control cells (p<0.05), while expression of protein p16 was up-regulated (p<0.01). Conclusion: TMP exhibits significant anti-proliferative and pro-apoptotic effects on the human gastric carcinoma cell line SGC-7901. NF-${\kappa}Bp65$, cyclinD1 and p16 may also play important roles in the regulation mechanisms.

• Asian Pacific Journal of Cancer Prevention
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• 제15권13호
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• pp.5117-5121
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• 2014

Endocrine-disrupting chemicals (EDCs) have been reported to interfere with estrogen signaling. Exposure to these chemicals decreases the immune response and causes a wide range of diseases in animals and humans. Recently, many studies showed that licorice (Glycyrrhiza glabra) root extract (LRE) commonly called "gamcho" in Korea exhibits antioxidative, chemoprotective, and detoxifying properties. This study aimed to investigate the mechanism of action of LRE and to determine if and how LRE can alleviate the toxicity of EDCs. LRE was prepared by vacuum evaporation and freeze-drying after homogenization of licorice root powder that was soaked in 80% ethanol for 72 h. We used 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as an EDC, which is known to induce tumors or cancers; MCF-7 breast cancer cells were used as a tumorigenic model. These were treated with TCDD and various concentrations of LRE (0, 50, 100, 200, $400{\mu}g/mL$) for 24, 48, and 72 h. As a result, TCDD stimulated MCF-7 cell proliferation, but LRE significantly inhibited TCDD-induced MCF-7 cell proliferation in a dose- and time-dependent manner. Expression of TCDD toxicity-related genes, i.e., aryl hydrocarbon receptor (AhR), AhR nuclear translocator, and cytochrome P450 1A1, were subsequently down-regulated by LRE in a dose-dependent manner. Analysis of cell cycle distribution after treatment of MCF-7 cells with TCDD and various concentrations of LRE showed that LRE inhibited the proliferation of MCF-7 cells via G2/M phase arrest. Reverse transcription-polymerase chain reaction and Western blot analyses also revealed that LRE dose-dependently increased the expression of the tumor suppressor genes p53 and p27 and down-regulated the expression of cell cycle-related genes. These data suggest that LRE can mitigate the tumorigenic effects of TCDD in breast cancer cells by suppression of AhR expression and cell cycle arrest. Thus, LRE can be used as a potential toxicity-alleviating agent against EDC-mediated disease.