• Journal of Applied Biological Chemistry
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• v.50 no.4
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• pp.281-287
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• 2007

Microorganisms were isolated from earthworm intestine and examined for their ability to degrade 3-methyl-4-nitrophenol (MNP), a main degradation product of the insecticide fenitrothion. An isolate that showed the best degradation of MNP was selected for further study. The 16S rRNA analysis showed that the isolate belongs to the genus of Burkholderia, close to phenanthrene-degrading Burkholderia sp. S4.9, and is named Burkholderia sp. SH-1. When time-course degradation of MNP by SH-1 was examined by high performance liquid chromatographic analysis, almost complete degradation of MNP was observed within 26 h. Colony forming unit value assays indicated that the isolate SH-1 was capable of utilizing MNP as a sole carbon source. SH-1 could also degrade p-nitrophenol (PNP) but could not degrade ortho-substituted nitroaromatics such as 2,4-, 2,6- and 2,5-dinitrophenol. Catechol was detected as the main degration product of MNP and PNP. SH-1 was also found in the soil from which earthworms were obtained. These results suggest that the dispersal of Burkholderia sp. SH-1 into different environment with the aid of earthworms is likely to play a role in bioremediation of the soil contaminated with MNP.

• Environmental Engineering Research
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• v.14 no.3
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• pp.170-173
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• 2009

This study examined the special technique of photocatalytic degradation (RPODisk) for removal of taste and odor causing materials, algae, and algal toxin. The RPODisk was effective for removal of these troublesome contaminants. It outperformed the fixed media and the UV irradiation for geosmin removal. The RPODisk performance was comparable to the combination of the UV irradiation with TiO2. The RPODisk performance was affected by the rotating speed. The faster the speed was, the better the performance. The RPODisk was also effective for removal of algae and algal toxin. The algal activity reduced by 80% after 30 mins of the treatment. More toxic microcystin (MC)-LR was more difficult to remove than MC-RR. The times for 50% removal were 23.7 mins for MC-LR and 14.1 mins for MC-RR. Almost 100 mins of the contact time was required to completely remove MC-LR at the rotating speed of 260 rpm.

• Korean Journal of Environmental Agriculture
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• v.11 no.2
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• pp.125-132
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• 1992

This study was conducted to know degradation products of the synthetic pyrethroid insecticide bifenthrin under soil, aqueous solution and UV-light irradation, and know its movement by leaching in soil. The major degradation product of bifenthrin was identified with 2-methylbiphenyl -3-y1 methanol by HPLC, UV, Mass and NMR under soil, aqueous solution and UV-light irradiation, The main degradation route was hydrolysis of the ester linkage. On exposure to UV-light, bifenthrin was decomposed almost completely in concentrations of 10 and 100 ppm in 24 hr but decomposed about 80% in 1,000 ppm. Bifenthrin was immobile in soil column system and on soil thin-layer chromatography system. Mostly bifenthrin remained in the 0-2.0㎝ layer of soil column and soil TLC.

• Mycobiology
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• v.47 no.2
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• pp.217-229
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• 2019

Two manganese peroxidases (MnPs), MnP1 and MnP2, and a laccase, Lac1, were purified from Trametes polyzona KU-RNW027. Both MnPs showed high stability in organic solvents which triggered their activities. Metal ions activated both MnPs at certain concentrations. The two MnPs and Lac1, played important roles in dye degradation and pharmaceutical products deactivation in a redox mediator-free system. They completely degraded Remazol brilliant blue (25 mg/L) in 10-30 min and showed high degradation activities to Remazol navy blue and Remazol brilliant yellow, while Lac1 could remove 75% of Remazol red. These three purified enzymes effectively deactivated tetracycline, doxycycline, amoxicillin, and ciprofloxacin. Optimal reaction conditions were $50^{\circ}C$ and pH 4.5. The two MnPs were activated by organic solvents and metal ions, indicating the efficacy of using T. polyzona KU-RNW027 for bioremediation of aromatic compounds in environments polluted with organic solvents and metal ions with no need for redox mediator supplements.

• Macromolecular Research
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• v.12 no.5
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• pp.466-473
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• 2004

We have used FT-IR spectra to explain the effects of hydrogen bonding between chitosan and polycaprolactam (PA6). A dynamic mechanical analysis study suggested that the optimum chitosan and PA6 miscibility under the conditions of this experiment were obtained at a blending ratio of 40:60. We studied the thermal degradation of chitosan blended with PA6 (chitosan/PA6) by thermogravimetric analysis and kinetic analysis (by the Ozawa method). Dry chitosan and PA6 exhibited a single stage of thermal degradation and chitosan/PA6 blends having> 20 wt% PA6 exhibited at least two stages of degradation. In chitosan/PA6 blends, chitosan underwent the first stage of thermal degradation; the second stage proceeded at a temperature lower than that of PA6, because the decomposition product of chitosan accelerated the degradation of PA6. The activation energies of the blends were between 130 and 165 kJ/mol, which are also lower than that of PA6.

• Proceedings of the Korean Reliability Society Conference
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• 2006.05a
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• pp.181-191
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• 2006

As an alternative to traditional life testing, degradation tests can be effective in assessing product reliability when measurements of degradation leading to failure can be observed. This article proposes a new model to describe the nonlinear degradation paths caused by nano-contamination for plasma display panels (PDPs) : a bi-exponential model with random coefficients. A sequential likelihood ratio test was executed to select random effects in the nonlinear model. Analysis results indicate that the reliability estimation can be improved substantially by using the nonlinear random-coefficients model to incorporate both inherent degradation characteristics and contamination effects of impurities for PDP degradation paths.

• Journal of Applied Reliability
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• v.18 no.1
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• pp.33-39
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• 2018

Purpose: Accelerated degradation tests can be effective in assessing product reliability when degradation leading to failure can be observed. This article proposes an accelerated degradation test model for highly reliable solid state drives (SSDs). Methods: We suggest a nonlinear mixed-effects (NLME) model to degradation data for SSDs. A Monte Carlo simulation is used to estimate lifetime distribution in accelerated degradation testing data. This simulation is performed by generating random samples from the assumed NLME model. Conclusion: We apply the proposed method to degradation data collected from SSDs. The derived power model is shown to be much better at fitting the degradation data than other existing models. Finally, the Monte Carlo simulation based on the NLME model provides reasonable results in lifetime estimation.

• The Research Journal of the Costume Culture
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• v.20 no.2
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• pp.238-250
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• 2012

This study examined the degradation behavior of SB(standard berberine) dye and SB dyed silk using HPLC-MS instrument after degradation in the hydrogen peroxide/ultraviolet ray radiation/oxygen system up to 9 days and 40 hours respectively. In the degraded samples, berberine was detected at 5.2 min in the SB dye and 5.3 min in the SB dyed silk with its molecular ion=336 and the UV spectra of quaternary alkaloid. Degradation product 3(m/z=102) newly appeared after 5 day degradation treatment with continued increase till the end of degradation treatment. The amount of berberine in the degraded dye decreased with degradation progression. In the silk dyeings, berberine was detected only up to 21 hour degradation sample. The amount of berberine decreased dramatically during the first 6 hours of degradation treatment. The CIELAB color measurement of the silk dyeings showed dramatic change in the b* value, near zero in the 40 hour degraded silk. CIELAB and Munsell color measurements were in agreement with the HPLC-MS results of the dyed silk in the change of berberine content that the degraded silk became white and lost yellow color.

• IE interfaces
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• v.12 no.3
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• pp.448-457
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• 1999

Accelerated degradation is concerned with models and data analyses for degradation of product performance over time at overstress and design conditions. Although there have been numerous studies with accelerated degradation theory in reliability, very few actually apply to parametric statistical analyses. This paper shows how to analyze degradation data, provides tests for how well the assumptions hold. Reel sensors, a sort of photointerrupters in home VCR, hive been tested, and least-square analyses are used to illustrate our approach. Tests for linearity of the performance-time relationship, dependence of the lognormal distribution, and the standard deviation on time are performed. The mean life of tested sensors is assessed at about 414,000 hours, and the Arrhenius activation energy of this reaction is concluded to be 0.39 eV as results.

• International Journal of Reliability and Applications
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• v.17 no.1
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• pp.21-49
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• 2016

Many mechanical, electrical and electronic products have more than one performance characteristics (PCs). For example the performance degradation of rubidium discharge lamps can be characterized by the rubidium consumption or the decreasing intensity the lamp. The product may degrade due to all the PCs which may be independent or dependent. This paper deals with the design of optimal bivariate step-stress partially accelerated degradation test (PADT) with degradation paths modelled by gamma process. The dependency between PCs has been modelled through Frank copula function. In partial step-stress loading, the unit is tested at usual stress for some time, and then the stress is accelerated. This helps in preventing over-stressing of the test specimens. Failure occurs when the performance characteristic crosses the critical value the first time. Under the constraint of total experimental cost, the optimal test duration and the optimal number of inspections at each intermediate stress level are obtained using variance optimality criterion.