• Journal of Radiation Protection and Research
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• 제25권1호
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• pp.45-51
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• 2000

본 연구의 목적은 마우스 주요 조직내의 방사성수은 침착을 알아보기 위하여 실험을 하였다. 건강한 ICR계 수컷 마우스를 사용하였고 두 개의 실험군을 설정하였다. 실험군은 방사성수은(0.005 uCi/b.w.)을 단독처치하고 스쿠알렌(200mg/kg)을 1일 2회씩 구강 처치하였다. 대조군은 실험군과 동일한 방법으로 방사성수은만 단독처치 하였다. 결과적으로 주요 침착 장기는 신장, 간, 혈액, 심장, 두개골이었다. 대조군의 경우 모든 장기에서 6시간째에 가장 높은 방사성수은 침착을 보였으나, 스쿠알렌을 처치한 실험군의 경우는 6시간째에 방사성침착이 유의하게 억제됨을 관찰 할 수 있었다(p<0.05). 결론적으로, 스쿠알렌이 방사성수은의 조직 침착을 억제시키는데 효과가 있는 것으로 사료된다.

• 한국환경농학회지
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• 제22권4호
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• pp.251-254
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• 2003

Phosphorous removal rate and emergent plant growth were examined of a surface-flow constructed treatment wetland system, whose dimensions were 31 meter in length and 12 meter in width. The system was established on floodplain in the down reach of the Kwangju Stream in Korea in one and half months from May to June 2001. Cattails(Typha angustiflora) were transplanted in the system. They were dug out of natural wetlands and stems were cut at about 40 cm height from their bottom ends. Water of the Kwangju Stream were funneled into it via a pipe by gravity flow and its effluent were discharged back into it. The stems of cattails grew from 45.2 cm in July 2001 up to 186 cm in September 2001 and the number of cattail stems per square meter increased from 22 in July 2001 to 53 in September 2001. The early establishment of cattails was good. Volume and water quality of inflow and outflow were analyzed from July 2001 through December 2001. Inflow averaged $40\;m^3/day$ and hydraulic retention time was about 1.5 days. The concentration of total phosphorous in influent and effluent was 0.85 mg/L, 0.41 mg/L, respectively. The average removal rate of total phosphorous in the system was about 52%. The retention efficiency was slightly lower, compared with that in surface-flow wetlands operating in North America, whose retention efficiency was reported to be about 57%. The lower abatement rate could result from the initial stage of the system and inclusion of two cold months into the six-month monitoring period. Root rhizosphere in wetland soils and litter-soil layers on bottoms were not properly developed. Increase of standing density of cattails within a few years will establish both root zones and substrates beneficial to the removal of phosphorous, which may lead to increase of the phosphorous retention rate. The system was submerged one time by heavy storm during the monitoring period. The inundation, however, scarcely disturb its environment.

• Asian-Australasian Journal of Animal Sciences
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• 제21권3호
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• pp.434-442
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• 2008

The objective of this study was to determine the optimum ratio of methionine to methionine plus cystine for growing pigs. A nitrogen balance trial was conducted using a total of 21 barrows (Large WhiteLandrace) over two replicates. The initial body weight was $20.36{\pm}1.22kg$ (mean${\pm}$SD) in the first replicate and $23.54{\pm}1.02kg$ (mean${\pm}$SD) in the second. For each replicate, the 21 pigs were randomly assigned to one of seven dietary treatments with three observations per treatment. The diets included a methionine and cystine-deficient basal diet with all other essential nutrients meeting nutrient requirements and six diets formulated with graded levels of DL-methionine (0.00, 0.03, 0.06, 0.10, 0.13, 0.16%) and $L-Cystine{\cdot}HCl{\cdot}H_2O$ (0.19, 0.15, 0.11, 0.07, 0.04, 0.00%). This resulted in ratios of methionine to methionine plus cystine of 41.3, 29.6, 35.3, 41.2, 46.0, 51.6 and 57.5%. Each experimental period lasted 12 days consisting of a seven-day adaptation period followed by a five-day total collection of urine and feces. During the collection period, pigs were fed 900 g/day for the first replicate and 1,200 g/day for the second replicate. The feed was provided in three equal portions at 0800, 1500, and 2200 h daily. Pigs had ad libitum access to water after feeding. There was a linear (p<0.01) and quadratic (p<0.01) effect on daily gain and feed conversion as the ratio of methionine to methionine plus cystine increased. Pigs receiving the diets providing a methionine to methionine plus cystine ratio of 51.6% had the best daily gain and feed conversion. Plasma urea nitrogen was also lowest for this treatment. Nitrogen retention increased (p<0.01) as the relative proportion of methionine increased up to 51.6% and then a downward trend occurred at 57.5%. The quadratic regression model, as well as one- and two- slope regression line models, were used to determine the optimum ratio of methionine to methionine plus cystine. Eliminating the 35.3% methionine to methionine plus cystine treatment resulted in $R^2$ values in excess of 0.92. The optimal ratio of methionine to methionine plus cystine was estimated to be 54.15% for nitrogen retention and 56.72% for plasma urea nitrogen.

• 생명과학회지
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• 제15권3호
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• pp.387-396
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• 2005

The aims of the study were to establish a short-term screening test for detecting testicular toxicity of chemicals in rats and to determine whether a 2-week administration period is sufficient to detect testicular toxicity of 2-bromopropane (2-BP) as an example. Male Sprague-Dawley rats were subcutaneously administered with 1000 mg/kg/day of 2-BP or its vehicle for 2 weeks. Ten male rats each were sacrificed on days 3, 7 and 14 after the initiation of treatment. Parameters of testicular toxicity included genital organ weights, testicular sperm head counts, epididymal sperm counts, motility and morphology, and qualitative and quantitative histopathologic examinations. The early histopathological changes observed on day 3 of treatment included degeneration of spermatogonia and spermatocytes, multinuclear giant cells, mature spermatid retention, vacuolization of Sertoli cells, and decreased number of spermatogonia in stages II and V. On day 7 of treatment, atrophy of seminiferous tubules, exfoliation of germ cells, degeneration of spermatogonia and spermatocytes, multinuclear giant cells, mature spermatid retention, vacuolization of Sertoli cells, decreased number of spermatogonia in stages II and V, and decreased number of spermatocytes in stages VII and XII. On day 14 after treatment, a significant decrease in the weights of testes and seminal vesicles was found. Atrophy of seminiferous tubules, exfoliation of germ cells, degeneration of spermatogonia and spermatocytes, mature spermatid retention, vacuolization of Sertoli cells, decreased number of spermatogonia in stages II and V, and decreased number of spermatocytes in all spermatogenic stages were also observed. In addition, a slight non-significant decrease in testicular sperm head counts, daily sperm production rate and epididymal sperm counts was found. The results showed that 2 weeks of treatment is sufficient to detect the adverse effects of 2-BP on male reproductive organs. It is considered that the short-term testicular toxicity study established in this study can be a useful tool for screening the testicular toxic potential of new drug candidates in rats.

• 대한치과교정학회지
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• 제34권6호
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• pp.526-536
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• 2004

본 연구는 급속상악확대술 시행 후 보정기간중에 지대치의 압박측 치근흡수에 불화나트륨의 경구 투여가 영향을 미치는지를 알아보기 위하여 시행되었다. 이차성징을 아직 나타내지 않은 10마리 소아기 암캐에 견치를 주지대치로 사용하는 주조형 상악 확대장치를 제작, 장착하였다 상악확대장치는 20일간에 걸쳐 5mm 확장시켰으며, 교합면 방사선사진을 이용하여 정중구개봉합의 이개를 확인하였다. 실험동물은 실험군 5 마리와 대조군 5 마리로 나뉘었으며, 보정기간 중 실험군에는 2.2 mg/kg/day의 불화나트륨 (불소로서 1.0mg/kg/day)을 캅셀제의 형태로 1 일 2 회로 나누어 단독 경구 투여하였다. 실험동물들을 보정 후 0 일, 15 일, 30 일, 45 일, 및 60 일째에 각 군당 한 마리씩 배정하여 충분한 마취로 희생시킨 후 상악골을 절취하였다. 이후 실험동물의 좌측 상악 견치의 압박측 치근표면과 압박측 견치 협면을 덮고 있던 골 조직의 치아측 표면을 주사전자현미경을 이용하여 관찰하였다. 본 실험에서 압박측 치근표면을 관찰한 결과 45일 보정군과 60일 보정군의 대조군에서 흡수소와가 발현되는 빈도가 높았다. 지대치 압박측 치근을 덮는 골면에 나타나는 흡수소와의 발현은 30일의 보정기간 이후부터 실험군에서 적게 나타남을 알 수 있었다. 차후 급속상악확대술을 시행하는 경우 효과적인 NaF의 투여시기와 용량에 대한 검증이 필요하리라 생각된다.

• Journal of Preventive Medicine and Public Health
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• 제40권2호
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• pp.155-161
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• 2007

Objectives : Bisphenol A diglycidyl ether (BADGE) is the major component in commercial liquid epoxy resins, which are manufactured by co-reacting bisphenol A with epichlorohydrin. This study was performed to show the developmental effects of prenatal and postnatal exposures to BADGE in male rat offspring. Methods : Mated female rats were divided into four groups, each containing 12 rats. The dosing solutions were prepared by thoroughly mixing BADGE in corn oil at the 0, 375, 1500 and 3000 mg/kg/day concentrations. Mated females were dosed once daily by oral gavage on gestation day (GD) 6 - 20 and postnatal day (PND) 0 - 21. Pregnant female dams were observed general symptoms and body weight. Also, male pups were observed the general symptoms, body weight, developmental parameters (e.g. anogenital distance, pina detachment, incisor eruption, nipple retention, eye opening, testis descent), organ pathologic changes and hormone levels of plasma. Results : Pregnant rats treated with BADGE died at a rate of about 70% in the 1500 mg/kg/day group and all rats treated with 3000 mg/kg/day died. Body weight, for male pups treated with doses of 375 mg/kg/day, was significantly lower than in the control group at PND 42, 56, and 63 (p<0.05). Evaluation of body characteristics including; separation of auricle, eruption of incisor, separation of eyelid, nipple retention, descent of testis, and separation of the prepuce in the BADGE treated group showed no difference in comparisons with the control group. AGD and adjusted AGD (mm/kg) for general developmental items in BADGE 375 mg/kg/day treated pups tended to be longer than in controls, however, these differences were not statistically significant. Relative weights of adrenal gland, lung (p<0.05), brain, epididymis, prostate, and testis (p<0.01) were heavier than in control in measures at PND 9 weeks. There were no significant changes in comparisons of histological findings of these organs. Loss of spermatids was observed in the seminiferous tubule at PND 9 weeks, but no weight changes were observed. The plasma estrogen levels were similar in the control and treatment groups at PND 3, 6 and 9 weeks. The plasma testosterone levels in the control group tended to increase with age. However, in the BADGE 375 mg/kg/day treated male pups it did not tend to increase. Conclusions : These findings suggest that BADGE is a chemical that has developmental effects consistent with it being an endocrine disruptor.

• 한국환경보건학회지
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• 제24권1호
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• pp.1-8
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• 1998

This study was carried to investigate the treatment characteristics of the phenol and catechol with an anaerobic fluidized bed reactor(AFBR) having a dimension of 9 cm i.d. and 1.25 m height. The reactor was operated at $35\pm 1\circ$C. The COD concentration of the effluent, the gas production rate and the composition of gas were measured to determine the performance of the AFBR as the hydraulic retention time(HRT) was decreased from 2 days to i day at 600 mg/l of the phenol and catechol concentration. Stable treatment of the phenol wastewater could be achieved with the AFBR at 18 days but the catechol wastewater couldn't be. At HRT 2 days, the phenol wastewater showed the COD reduction efficiency of 93% and the gas production of 2.7 l/day and the catechol wastewater was obtained the COD reduction efficiency of 82% and the gas production of 0.72 l/day. Also at HRT 1 day the phenol and catechol wastewater showed the COD reduction efficiency of 95% and 73% and the gas production of 4.0 l/day and 1.25 l/day, respectively.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제10권S_1호
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• pp.35-40
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• 2001

Effect of the addition of an enzyme/microbial additive(EMA) to enhance anaerobic digestion of the primary sludge was investigated. Two laboratory scale anaerobic digester were operated with primary sludge taken from a municipal wastewater treatment plant. The digester receiving EMA with the sludge feed performed better than the control digester, when both were operated at 10-days and 15-days Solid Retention Time(SRT). Addition of EMA to the experimental digester provided 7%(10-days SRT) and 16%(15-days SRT) higher gas production compared to the control digester when both were fed with the same amount of volatile solids. The reduction in volatile solids was 24% better in the experimental digester compared to the control ar 10-days SRT, and the improvement 10% at 15-day SRT. Improvement in COD reduction, and fecal coliform density reduction were also seen in the experimental digester due to EMA addition compared to the control both ar 10-days SRT and 15-day SRT operation. Preliminary cost benefit analysis for a wastewater treatment plant showed that approximately $115/day in gas production improvements can be realized upon addition of EMA to primary sludge anaerobic digesters operating at 10-day SRT. The value of increased gas production was $172/day if the same digesters are operated with EMA addition at 15-day SRT.

• 한국가금학회지
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• 제22권4호
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• pp.193-202
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• 1995

This study was carried out to investigate the effects of diverse dietary Ca levels and to determine whether bone mineral metabolism is influenced by the arnount of dietary Ca when given a choice of diets containing various levels of Ca. Forty Hy-line brown laying hens housed in separate cages were fed self-selected Ca diets. Birds were allowed a 7-day adaptation period followed by an 8-day collection period. Feed and water were available for ad libitum consumption. Eggs and excreta were collected at 6-h intervals during the day for mineral analysis. The Ca contents in excreta and retained Ca in the body on egg forming day were proportional to the amount of daily Ca intake. The retained Ca in the body were 0.97 g in control and 1.24~1.74 g in self-selected groups, respectively. Daily Ca contents (%) in tibial cortex were not consistent with feeding time intervals. The Ca content in tibial medulla in control group was lower than those of self-selected feeding groups(P<.05). The medullary Ca content in all treatment groups increased from 10:00 to 16:00 in a day. Ca content in plasma was low between 10:00 and 16:00 and was high between 22:00 and 04:00 in the following day.

• 환경위생공학
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• 제14권3호
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• pp.130-138
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• 1999

The feasibility of municipal sewage sludge digestion was investigated by using thermophilic anaerobic sequencing batch reactor(ASBR). One-day settle time was enough for the high performance of solid-liquid separation. The conversion of semi-continuous mode to sequencing batch mode is easily achieved without any adverse effects, although the large amount of sludge equal to the volume ratio of 0.3~06 to reactor volume was added in the feed step of the start-up. The ASBRs had higher conversion capability of organics to biogas than the control reactor. Gas yields of the ASBRs were increased by the average of 50% over the control reactor across a range of hydraulic retention time(HRT)s from 10days to 5days. The thermophilic reactors showed higher gas production than mesophilic reactor. Removal efficiencies of organic matter exceeded 80% on the basis of supernatants, except that at the reactor. Solid-liquid separation was essential in the performance of the ASBR, especially, at the lower HFT. The ASBRs were highly efficient in the retention of activated biomass within the reactor. thus compensating for increased equivalent organic loading rate through increased solids retention times followed by the increased solids, while maintaining shorter HRTs.