• 대한치과교정학회지
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• 제33권5호
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• pp.351-358
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• 2003

니켈과 크롬은 대부분의 교정장치를 제작하는데 사용되는 합금을 구성하는 주요한 금속이다. 그러나 이들 금속은 과민반응, 피부염, 천식 등의 주요한 원인이 되며, 이들 금속의 우발적인 흡입에 의해 암이 유발될 수 있음이 보고된 바 있다 이에 하악 standard edgewise브라켓을 이용한 사분악의 교정장치를 $37^{\circ}C,\;,0.05\%$ NaCl용액에 저장하여 교정장치의 부식에 의해 유리된 니켈과 크롬을 Inductively Coupled Plasma(ICP) spectroanalyzer를 이용하여 측정하였다. 교정장치로부터, 1일 평균 $9.83-70.0{\mu}g/day$의 니켈이 유리되었으나, 크롬은 10ppb 측정한계에서 측정불가능 하였다. 니켈 유리량은 제품에 따라 유의한 차이를 가져왔다 Galvanic조건이나 Sand blasting처리는 니켈 유리량에 증가를 가져왔으나 통계학적으로 유의하지 않았다.

• Environmental Engineering Research
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• 제10권6호
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• pp.294-305
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• 2005

The effectiveness of fly ash-, quicklime-, and quicklime-fly ash-based stabilization/solidification(S/S) in chromium(Cr) contaminated soils was investigated using modified semi-dynamic leaching tests. Artificial soil samples composed of kaolinite or montmorillonite contaminated with chromium nitrate(4000 mg $Cr^{3+}\;kg^{-1}$ of solid) were prepared and then subjected to S/S treatment using quicklime, fly ash, or quick lime-fly ash. The effectiveness of the treatment was evaluated by assessing the cumulative fraction of leached $Cr^{3+}$ as well as, by computing the effective diffusivity ($D_e$) and the leachability index (LX) of the treated samples. The reduction in $Cr^{3+}$ release for the untreated samples was more pronounced in the presence of montmorillonite, which was attributed to sorption. Treatment with quicklime, fly ash, or quick lime-fly ash was significantly effective in reducing $Cr^{3+}$ release most probably due to the formation of pozzolanic reaction products and $Cr(OH)_3$ precipitation. The most effective treatment was observed in montmorillonite-sand soil samples treated with quicklime-fly ash (99.8% removal). The mean $D_e$ decreased significantly and the mean LX was greater than 9 for all treated samples, indicating that the treated soils were acceptable for "controlled utilization". The mechanism controlling $Cr^{3+}$ leaching from all treated samples during the first 5 days appeared to be diffusion.

• 한국환경보건학회지
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• 제47권2호
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• pp.144-154
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• 2021

Objectives: This study was intended to identify hazard contribution by region, media, and chemical by calculating a hazard-based index using pollutant release and transfer register (PRTR) data. Methods: PRTR data for the period 2011 to 2016 was analyzed to examine the regional trends in toxic releases in terms of quantity and to create a corresponding hazard-based index. For the hazard-based index, the Risk-Screening Environmental Indicators (RSEI) Model was used. Results: The results of the trend analysis show that total releases decreased slightly, but health hazard levels increased consistently. According to the outcome of regional contribution analysis of the hazard-based index, Chungcheongnam-do, Jeollabuk-do and Gyeonggi-do Provinces showed a high ratio in the index for air and water release pollutants, while Gyeongsangbuk-do and Gyeongsangnam-do Provinces showed a high ratio in the index of soil release and waste transfer pollutants. Also, as a result of the analysis of the top ranked substances in the hazard-based index, it was found that chromium, cobalt and its compounds, and ethylene oxide contributed greatly to air release substances, while chromium, benzene, and lead and its compounds contributed greatly to water release substances. Conclusion: These results showed considerable disparities between total release and health hazard levels, especially in the analysis of contribution by regions and by chemical substance. Therefore, the hazard-based index should be used both to support a more comprehensive and robust approach to screening of chemicals for environmental health policy and for management.

• 대한치과교정학회지
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• 제19권2호
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• pp.75-84
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• 1989

The purpose of this experiment was to measure the amounts of nickel and chromium released from a simulated orthodontic appliance in artificial saliva. Simulated mandibular half-arch orthodontic appliances were composed of American Iron and Steel Institute type 304 brackets, Permachrome, Elgiloy, Australian wire, T.M.A. and Nitinol. The amounts of nickel and chromium released from sample were measured with atomic absorption spectrophotometer after 3, 6, 9, 12, 15 days. The cumulative amounts of nickel released from Permachrome, Elgiloy, Australian wire and T.M.A. reached a plateau after 6 days. But the cumulative amounts of nickel released from Nitinol increased continuously. Significant amounts of both nickel and chromium were solubilized from the simulated orthodontic appliances into artificial saliva. After 15 days, total cumulative amounts of nickel were $152.15{\mu}g$, $150.27{\mu}g$, $134.74{\mu}g$, $114.67{\mu}g$ and $93.39{\mu}$ from the Elgiloy, Australian wire, Nitinol, Permachrome and T.M.A., respectively. Total cumulative amounts of chromium from Permachrome, Australian wire, Elgiloy, Nitinol and T.M.A. were $100.83{\mu}g$, $83.64{\mu}g$, $81.61{\mu}g$, $14.90{\mu}g$ and $12.43{\mu}g$, respectively. The result showed that nickel released from Elgiloy and chromium released from Permachrome were more than any others.

• Journal of Pharmaceutical Investigation
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• 제38권3호
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• pp.177-182
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• 2008

The purposes of this study were to prepare dual-layered coated compact pellets containing three nutrients Glucose, Chromium picolinate, Vitamin C) for rumen bypass. The core compact pellets were prepared by an extrusionspheronization method and then double layered coated with pH independent EC (ethyl cellulose) and pH-dependent polymers ($Eudragit^{(R)}$ E100) using a fluid-bed spray coater. Depending on the coating levels of EC and $Eudragit^{(R)}$ E100, release profiles were variable in simulated rumen (pH 6.8) and abomasums (pH 2.0) fluid using USP apparatus I (basket method). When compact pellets were coated with EC (about 10% level in inner layer) and then $Eudragit^{(R)}$ E100 (20% level in outer layer) in a dual-layered manner, rumen-bypass delivery resisting rumen fluid followed by release in abomasums fluid could possible. The friability was also satisfactory based on chewing behavior of ruminants. The dual-layered coated compact pellets showed smooth surface and distinct inner/outer layers using scanning electron microscopy (SEM). The current rumen bypass delivery system can be also applicable to deliver other nutrients in ruminants.

• Journal of the Korean Wood Science and Technology
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• 제33권3호통권131호
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• pp.53-63
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• 2005

본 연구는 바다목장사업 소재로서 방부처리 목재의 사용 가능성에 대한 기초자료를 얻고자 실시하였다. CCA, CCFZ, ACQ 처리재 내 포함된 유해 중금속의 해수에 대한 용탈 안전성을 평가하기 위해 각각 2% 및 3% 방부제 수용액으로 처리한 목재를 증류수, 자연해수 및 인공적으로 염도를 조절한 인공해수에 41일간 폭로하여 기간 별 각 성분의 용탈량을 측정하였다. 바닷물에서 CCA 처리재의 구리 및 크롬의 용탈은 거의 일어나지 않았으며, 다소 많은 비소의 용탈이 있었으나 증류수에서의 용탈에 비해 적은 양을 나타내었다. CCFZ는 증류수에서 크롬과 아연의 용탈량이 매우 높았으나 바닷물에서는 훨씬 적은 용탈량을 나타내었다. 방부제 흡수량 및 인공해수의 염분 농도에 따른 용탈량에는 큰 차이가 없었다. ACQ 처리재는 CCA 및 CCFZ 처리재에 비해 많은 구리 용탈을 나타내었으며 용탈 매체에 따른 차이는 나타나지 않았다.

• The Journal of Advanced Prosthodontics
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• 제7권2호
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• pp.172-177
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• 2015

PURPOSE. The purpose of this study was to evaluate cell toxicity due to ion release caused by galvanic corrosion as a result of contact between base metal and titanium. MATERIALS AND METHODS. It was hypothesized that Nickel (Ni)-Chromium (Cr) alloys with different compositions possess different corrosion resistances when contacted with titanium abutment, and therefore in this study, specimens ($10{\times}10{\times}1.5mm$) were fabricated using commercial pure titanium and 3 different types of Ni-Cr alloys (T3, Tilite, Bella bond plus) commonly used for metal ceramic restorations. The specimens were divided into 6 groups according to the composition of Ni-Cr alloy and contact with titanium. The experimental groups were in direct contact with titanium and the control groups were not. After the samples were immersed in the culture medium - Dulbecco's modified Eagle's medium[DMEM] for 48 hours, the released metal ions were detected using inductively coupled plasma mass spectrometer (ICP-MS) and analyzed by the Kruskal-Wallis and Mann-Whitney test (P<.05). Mouse L-929 fibroblast cells were used for cell toxicity evaluation. The cell toxicity of specimens was measured by the 3-{4,5-dimethylthiazol-2yl}-2,5-diphenyltetrazolium bromide (MTT) test. Results of MTT assay were statistically analyzed by the two-way ANOVA test (P<.05). Post-hoc multiple comparisons were conducted using Tukey's tests. RESULTS. The amount of metal ions released by galvanic corrosion due to contact between the base metal alloy and titanium was increased in all of the specimens. In the cytotoxicity test, the two-way ANOVA showed a significant effect of the alloy type and galvanic corrosion for cytotoxicity (P<.001). The relative cell growth rate (RGR) was decreased further on the groups in contact with titanium (P<.05). CONCLUSION. The release of metal ions was increased by galvanic corrosion due to contact between base metal and titanium, and it can cause adverse effects on the tissue around the implant by inducing cytotoxicity.

• 대한치과교정학회지
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• 제20권2호
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• pp.381-390
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• 1990

The purpose of this study was to evaluate the effects of heat treatment on mechanical properties in $0.016^{{\prime}{\prime}}{\times}0.022^{{\prime}{\prime}}$ blue Elgiloy wires and to measure the amounts of nickel and chromium released from the wires in artificial saliva. Ultimate tensile strength, yield strength and elongation were measured with universal testing machine (Instron). and the amounts of nickel and chromium released from the sample were measured with atomic absorption spectrophotometer after one week immersion in the artificial saliva. Ultimate tensile strength and yield strength were progressively increased below $1000^{\circ}F$, but elongation was decreased. And the results were reversed above $1100^{\circ}F$. After heat treatment of the sample for 9 minutes at $1000^{\circ}F$, the maximum tensile strength and yield strength were $213.6kg/mm^2$, $140.1kg/mm^2$, respectively. Both tensile strength and yield strength were decreased progressively above $1100^{\circ}F$. Elongation was appeared the minimum value (8.6%) after heat treatment for 9 minutes and 12 minutes at $1000^{\circ}F$. There was a pronounced increase in nickel and chromium liberation with increasing time and temperature. The maximum amounts of nickel and chromium released form the sample were $4.947{\mu}m/cm^2$, $3.088{\mu}g/cm^2$, respectively after heat treatment for 12 minutes at $1300^{\circ}F$. Heat treatment is applied to orthodontic wires, especially cobalt-chromium alloys, for the purpose of stress-relievning and hardening. When the heat-treatment of orthodontic wires, the heating procedure should be well controlled in order to have no effect on corrosion resistance and mechanical properties.

• Corrosion Science and Technology
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• 제14권4호
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• pp.166-171
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• 2015

Knowledge of how metal releases from the stainless steels used in food processing applications and cooking utensils is essential within the framework of human health risk assessment. A new European standard test protocol for testing metal release in food contact materials made from metals and alloys has recently been published by the Council of Europe. The major difference from earlier test protocols is the use of citric acid as the worst-case food simulant. The objectives of this study were to assess the effect of citric acid at acidic, neutral, and alkaline solution pH on the extent of metal release for stainless steel grades AISI 304 and 316, commonly used as food contact materials. Both grades released lower amounts of metals than the specific release limits when they were tested according to test guidelines. The released amounts of metals were assessed by means of graphite furnace atomic absorption spectroscopy, and changes in the outermost surface composition were determined using X-ray photoelectron spectroscopy. The results demonstrate that both the pH and the complexation capacity of the solutions affected the extent of metal release from stainless steel and are discussed from a mechanistic perspective. The outermost surface oxide was significantly enriched in chromium upon exposure to citric acid, indicating rapid passivation by the acid. This study elucidates the effect of several possible mechanisms, including complex ion- and ligand-induced metal release, that govern the process of metal release from stainless steel under passive conditions in solutions that contain citric acid.

• Asian-Australasian Journal of Animal Sciences
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• 제13권4호
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• pp.528-534
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• 2000

Sixteen specific pathogen free 4-wk-old crossbred weanling pigs were allotted into a $2{\times}2$ factorial design to evaluate chromium picolinate (CrPic) on growth and physiological responses. Two factors included (1) no Cr or 400 ppb Cr supplementation from chromium picolinate and (2) lipopolysaccharide (LPS) injection on day 21 (d 21) and 35 (d 35) compared to saline application. Plasma samples and rectal temperature were obtained from all piglets before (h 0) and at 2 h (h 2), 4 h (h 4), 8 h (h 8), and 24 h (h 24) after LPS injection ($200{\mu}g/kg$ BW, intraperitoneally). The rectal temperature on d 21 was significantly decreased (p<0.05) of about $0.36^{\circ}C$ with Cr supplementation before LPS injection. After LPS injection, the daily gain of piglets was decreased during d 35-38. Supplementation of Cr had no effect in general on growth performance particularly after LPS injection. The plasma glucose, triglycerides and urea nitrogen concentrations were changed in different ways after LPS injection. Plasma cortisol level was significantly elevated at h 2 after LPS injection on d 21 and d 35. The supplementation of Cr in the diet can delayed plasma cortisol release on d 35. The results suggest that 400 ppb Cr supplementation from CrPic may modulate the physiological response during immune stress in weanling pigs.