This study was designed to predict the risk of a hazard chemical, vinyl chloride, by applying dose-response assessment that are one of the major process in practicing risk assessment. After extrapolating from the high dose exposure of vinyl chloride based upon animal carcinogenic data to the low dose exposed to human using several mathematical models, we calculated the cancer potency factors as well as virtually safe dose and the resulted values were compared. This process will provide the new insight to assess the risk of a chemical accurately imposed to human in the future.

the present study was carried out to develop a completely defined culture system and determine if high NaCl concentrations in defined (PVA added) or semi-defined (BSA added) medium is toxic to bovine embryos. Oocytes from slaughterhouse ovaries were matured and fertilized in vitro. After 30 h of insemination, only 2-cell stage embryos were selected and cultured for this experiment. The culture media used were as follows : TLP(114 mM of NaCl) + BSA (3 mg/ml), TLP + PVA (1 mg/ml), mTLP(96 mM of NaCl) + BSA, mTLP + PVA. Six to ten embryos were placed into a 301 drop of each medium and the embryos were examined at 10 day post-insemination without medium renewal. The experiment was replicated 4 times. All data were analyzed by chi-square. There were no significant differences among TLP-BSA, mTLP-BSA and mTLP-PVA in blastocyst development (21.6, 17.2 and 20.2%), respectively. Also, no differences were obtained in hatching rates (11.7, 9.9 and 12.2%), respecitively. However, there were significant differences between TLP-PVA (1.7% and 0.6%) and other group in blastocyst formation and hatching rates, respectively (p<0.01). Development of in vitro produced embryos cultured in BSA containing medium was not affected by high NaCl concentration, but in the completely defined medium, embryonic development was highly affected by NaCl. This study shows that reduced NaCl concentration in completely defined medium is beneficial for development of bovine pre-implantation embryos in vitro.

염화철(Ferrous Choloride) 증기의 고온 수소환원 반응을 통한 미립질 철분말의 생성속도에 대한 이론적인 해석돠 실험을 수행하였다. 철분말의 생성기구는 염화철이 증발하여 생성된 증기와 운반가스인 알곤을 혼합하여 반응부로 유입시키고 수소에 의한 고온환원반을을 통하여 철분말과 함께 부산물인 염화수소(HCI) 가스를 얻게 된다. 생성된 반응부 후미에 설치한 유기용매 포집기를 이용하여 회수하였으며, 염화수소는 가성소다 수용액에 흡수시키고 이를 적정함으로써 초기 반응물인 염화철의 전환율을 계산하였다. 반응속도식의 반응물에 대하여 1차반응(1st-order reaction)이고 염화철 증가와 운반체인 알곤가스가 평형상태일 때의 속도상수는 k=7,879exp(-53,840/RT)dm3/mole.sec으로 표시되며, 이때의 활성화에너지는 53.84kJ/mole이었다. 철분말의 TEM 사진에 의하면 입도범위는 0.1~1.0μm이며, 반응온도 및 가스유량에는 크게 영향을 받지 않는것으로 나타났다.

The in vitro effects of trisodium phosphate and cetylpyridinium chloride on E. coli O157:H7 and L. monocytogenes were investigated. The trisodium phosphate and cetylpyridinium chloride was bactericidal toward E. coli O157:H7 and L. monocytogenes. The killing effects of the 1 × 10^(-2) M trisodium phosphate on E. coli O157:H7 and L. monocytogenes were 30-40%, 40-50%, respectively. The killing effects of the 5 × 10^(-7) M cetylpyridinium chloride on E. coli 0157:H7 and L. monocytogenes were 90-95%, 95-99%, respectively. The killing effects of the trisodium phosphate was 105 times that of the cetylpyridinium chloride. Factors effecting the bactericidal action of trisodium phosphate and cetylpyridinium chloride were investigated and the action depended on temperature and pH.

수산화물법에 의해 제작된 α-stannic acid의 열분해 거동과 SnO2분말의 성질에 미치는 잔류염소이온의 영향을 관찰하였다. SnCl4와 NH4OH 수용액을 중화시켜 α-stannic acid침전물을 제작하고 NH4NO3수용액으로 세척하였다. 분말내의 잔류 염소이온의 양을 주절하기 위하여 세척정도를 3단계로 조정하였다. 세척후 100˚C에서 건조하고, 500˚C ~ 1100˚C에서 하소함으로써 SnO2분말을 제조하였다. α-stannic acid의열분해 거동ㅇ르 DT-TGA 와 FTIR을 통하여 관찰하고, SnO2분말의 조성과 입자크기 및 비표면적을 각각 AES, TEM 및 BET을 통하여 측정하였다. 잔류 염소이온 양이 감소되면, 저온 하소시 일차입자의 상대적 크기가 커지는 반면 고온하소시에는 상대적으로 감소되었ㄷ. 잔류 염소이온의 일부는 α-stannic acid내의 격자산소 자리에 위치함으로써, 저온가열시 결정수탈리와 결정화를 지연시키고 또한 고온가열시에는 이의 증발에 의해 산소공공이 생성되어 소결을 촉진시킨다고 제의하였다.

Dansyl, bansyl, dabsyl chloride의 pyridine에 대한 친핵적 치환반응의 속도론적 연구를 0℃, methanol-acetonitrile의 혼합용매계에서 수행하였다. 같은 반응 조건에서 pyridine에 대한 기질들의 반응성은 dabsyl>dansyl>bansyl chloride의 순이었다. ρ_N와 β값이 각각 -2.29∼-4.66, 0.537∼0.901로 값이 컸으며, 이는 전이상태에서 결합형성이 비교적 진전됐음을 나타낸다. 분광용매화 상관관계에서 MeCN함량이 증가함에 따라 전이상태에서의 결합형성이 증가한 것으로부터 극성-편극성(π^*)이 수소결합주게능력(α)보다 더 크게 기여함을 알 수 있었다. 결론적으로 dansyl, bansyl, dabsyl chloride의 pyridine에 대한 반응은 associative S_N 2형 반응메카니즘으로 일어남을 알 수 있었다.

In this study, solid-liquid separation conditions for coagulation and sedimentation experiments using inorganic coagulant (aluminum sulfate and Poly-Aluminum Chloride (PAC)) were optimized with brine wastewater discharged by the epoxy-resin process. When the turbidity and suspended solid (SS) concentration in raw wastewater were 74 NTU and 4.1 mg/L, respectively, their values decreased the lowest in a coagulant dosage of 135.0 - 270.0 mg Al3+/L. The epoxy resin was re-dispersed in the upper part of wastewater treated above 405.0 mg Al3+/L. The removal efficiencies of turbidity and SS via dosing with aluminum sulfate and PAC were evaluated at initial turbidity and SS of 74 - 630 NTU and 4.1 - 38.5 mg/L, respectively. They increased most in the range from 135.0 - 270.0 mg Al3+/L. The solid-liquid separation condition was quantitatively compared to the correlation of SS removal efficiency between the coagulant dosage and SS concentration based on the concentration of aluminum ions. The empirical formula,   , shows the relationship between SS removal efficiency (R) and coagulant dosage (D) at 38.5 mg/L; it produced high correlation coefficients (r2) of 0.9871 for aluminum sulfate and 0.9751 for PAC.

This study aimed to investigate the effects of soil amendment (heat-expanded clay and active carbon) and planting of Dendranthema zawadskii var. latilobum on the remediation of salt-affected soil and the plant growth under high calcium chloride (CaCl2) concentration. The experimental group comprised treatments including Non treatment (Cont.), heat-expanded clay (H), active carbon (AC), planting (P), heat-expanded clay+planting (H+P), active carbon+planting (AC+P). A 200 mL solution of CaCl2 at a concentration of 10 g·L-1 was applied as irrigation once every 2 weeks. Compared to the Cont., the incorporation of the ‘heat-expanded clay’ amendment decreased electrical conductivity of the soil leachate and cation exchange capacity, whereas the growth of Dendranthema zawadskii var. latilobum was relatively increased. These results suggest that the combination of ‘heat-expanded clay’ amendment and planting will mitigate negative effect of de-icing salts and improve plant growth in salt-contaminated roadside soils.

This study was conducted to investigate the growth of Dendranthema zawadskii in damaged soils when they are treated with improvement agents. The treatments consisted of a control (unamended field soil) and the application of a loess ball of 1 cm to the field soil. According to the degree of damage the de-icing agent had caused, the soils were divided into 3 areas (based on the yellowing of Pinus densiflora for. multicaulis in soil surveys): H (high saline), M (medium saline), and L (low saline). A total of six treatments were performed: D. zawadskiia plant without soil amendment (H; high saline soil, M; medium saline soil, L; low saline soil), and a D. zawadskiia plant with loess ball on the soil surface (H.L; high saline soil with loess ball, M.L; medium saline soil with loess ball, L.L; low saline soil with loess ball). The results showed that D. zawadskiia growth went from highest to lowest in the order: M.L > L.L > M > L > H.L > H. Plant growth results showed that soils treated with soil amendments (loess ball) were better for D. zawadskii growth than untreated soils.

This study aims to identify the most tolerant species under salinity stress from amongst Asteraceae and Poaceae. The seeds of six species were exposed to different concentrations of CaCl2 (0, 9, 18, 45, 90 mM) and NaCl (0, 17, 34, 85, 170 mM), and germination was measured once every two days. The results indicated that percent germination of the six species of Asteraceae and Poaceae seeds were affected differently by changes in salinity concentration. Seed germination was reduced as salinity levels increase, and longer mean germination times correlated to lower percent germination and earlier germination cessation. Both Asteraceae and Poaceae seeds had the highest germination rates at 18 mM CaCl2 and 34 mM NaCl, and seed germination and growth were severely reduced at salinities greater than 90 mM CaCl2 and 170 mM NaCl. In the seeds of Poaceae, salt resistance was strong in the order of Miscanthus sinensis Andersson, Pennisetum alopecuroides (L.) Spreng., and Phragmites communis Trin. In the seeds of Asteraceae, salt resistance was strong in the order of Dendranthema zawadskii var. latilobum (Maxim.) Kitam, Aster yomena (Kitam.) Honda, and Dendranthema boreale (Makino) Ling ex Kitam.. Overall, the germination rate was higher in Asteraceae than in Poaceae. This study demonstrated that Dendranthema zawadskii var. latilobum (Maxim.) Kitam. is the most tolerant species and that a relationship exists between the salt tolerance of percent germination and the mean germination time in the leaves.

콘크리트는 인장력에 취약한 재료적 특징을 갖기 때문에 콘크리트 구조물의 사용기간 중에 발생하는 균열은 내구성능 평가 시 필히 고려되어야 한다. 본 연구에서는 두 수준의 강도를 고려한 플라이애시 콘크리트를 배합하여 옥외 폭로 시험을 실시하였다. 노출 환경은 비말 조건으로 설정하였으며, 균열 폭이 콘크리트의 염화물 확산 거동에 미치는 영향을 평가하고자 각 배합의 시편에 0.1 mm 간격으로 최대 1.0 mm 까지의 균열 폭을 야기하였다. 그 후 3가지 수준의 노출기간(180일, 365일, 730일)을 고려하여 겉보기 염화물 확산계수 및 표면 염화물량을 산출하였다. 균열 폭의 증가에 따라 두 배합 모두 확산계수가 증가하였으며, 노출기간이 증가함에 따라 확산계수는 감소하였다. 또한 노출 기간이 증가함에 따라 균열 폭이 확산계수에 미치는 영향이 감소하였는데, 이는 염소 이온 기반 수화물이 콘크리트의 확산성을 저감시키기 때문으로 사료된다. 표면 염화물량 거동은 겉보기 염화물 확산계수 거동 대비 균열 폭의 증가에 따른 뚜렷한 변화 거동이 발생하지 않았으며, 고강도 배합에서 보통 강도 배합 대비 78.9 % ~ 90.7 %의 표면 염화물량을 나타내어 강도와의 상관관계를 갖는 것으로 판단된다.