• BMB Reports
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• v.47 no.10
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• pp.575-580
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• 2014

In this study, we investigate whether arsenite-induced DNA damage leads to p53-dependent premature senescence using human glioblastoma cells with p53-wild type (U87MG-neo) and p53 deficient (U87MG-E6). A dose dependent relationship between arsenite and reduced cell growth is demonstrated, as well as induced ${\gamma}H2AX$ foci formation in both U87MG-neo and U87MG-E6 cells at low concentrations of arsenite. Senescence was induced by arsenite with senescence-associated ${\beta}$-galactosidase staining. Dimethyl- and trimethyl-lysine 9 of histone H3 (H3DMK9 and H3TMK9) foci formation was accompanied by p21 accumulation only in U87MG-neo but not in U87MG-E6 cells. This suggests that arsenite induces premature senescence as a result of DNA damage with heterochromatin forming through a p53/p21 dependent pathway. p21 and p53 siRNA consistently decreased H3TMK9 foci formation in U87M G-neo but not in U87MG-E6 cells after arsenite treatment. Taken together, arsenite reduces cell growth independently of p53 and induces premature senescence via p53/p21-dependent pathway following DNA damage.

• Molecules and Cells
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• v.25 no.2
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• pp.272-278
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• 2008

The carbon-ion beam (CIB) generated by the heavy-ion medical accelerator in Chiba (HIMAC) was targeted to 7-day-old rice. Physiological parameters such as growth, and gene expression profiles were examined immediately after CIB irradiation. Dose-dependent growth suppression was seen three days post-irradiation (PI), and all the irradiated plants died by 15 days PI. Microarray (Agilent rice 22K) analysis of the plants immediately after irradiation (iai) revealed effects on gene expression at 270 Gy; 353 genes were up-regulated and 87 down-regulated. Exactly the same set of genes was affected at 90 Gy. Among the highly induced genes were genes involved in information storage and processing, cellular processes and signaling, and metabolism. RT-PCR analysis confirmed the microarray data.

• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.391-396
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• 2011

Recently it revealed that urban runoff was one of the major source that contaminates the river, lake and estuary because it contains toxic compounds such as heavy metals and Poly Aromatic Hydrocarbons (PAHs) as well as suspended solids, organic compounds and nutrients. The engineered polymetric media in this research were developed for reducing pollutants in urban runoff and would be used to be charged in the storm water treatment equipment. The engineered media that were composed of the polypropylene was foamed to have the buoyancy and then shattered by mechanical for the efficient filtration. In this study, Spherical Expanded Polypropylene Media (SEPM), Crushed Polypropylene Media (CPM), Large Crushed Expanded Polypropylene Media (LCEPM), Small Crushed Expanded Polypropylene Media (SCEPM) were made from polypropylene. Surface characteristics of the developed media were determined by scanning electron microscopy analyses. Also, removal efficiencies of SS, $COD_{Cr}$ in the artificial road runoff and the bed headloss by media and particle pollutants captured by media were examined. Results on the surface characteristics of media indicated that SCEPM had the largest specific surface area, $0.80m^2/g$, the lowest specific gravity, 0.091, and the biggest porosity, 0.63, because of crushing the media at the process of manufacturing. And the SCEPM's removal efficiencies of TSS and $COD_{Cr}$ in the artificial road runoff were 92.9% and 83.6%, respectively and the headloss of SCEPM was the least of them.

• Nuclear Engineering and Technology
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• v.56 no.11
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• pp.4531-4539
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• 2024

Accurate measurement of the dose delivered to patients is crucial in any radiation therapy, including C ion beam radiotherapy, to ensure effective treatment and minimize the risk of damage to healthy tissues. The accessibility of thermoluminescence (TL) - based materials for carbon ion beam dosimetry continues to be constrained. With the aim of this, an investigation has been done to study the TL properties of the Terbium (Tb) doped LiCaAlF₆ phosphor following irradiation with C ion beam. The LiCaAlF₆: Tb phosphor has been synthesized using melting method in argon gas atmosphere. TL glow curves has been analyzed on exposure to carbon ion beams at energies of 85 MeV and 50 MeV within the fluence range of 10⁹ - 10¹² ions/cm². The TRIM code, relying on Monte Carlo simulation, has been employed to compute parameters such as absorbed dose, ion range, and energy loss. The Tb-doped LiCaAlF₆ phosphor exhibits a glow curve structure with distinctly resolved peaks at 130 ℃ and 325 ℃. Notably, the TL intensity has been significantly increased by 10⁵ times than that of undoped LiCaAlF₆. This enhancement is attributed to the generation of a high density of Tb-associated defects within the energy band gap. The TL enhancement has been elucidated based on charge compensation mechanism. Further, TL glow curve shape and structure remain consistent across different energies, i.e., 85 and 50 MeV C ion beams, indicating an energy-independent behavior of this phosphor. Nevertheless, the TL intensity at 85 MeV is higher compared to that at 50 MeV. Detailed dosimetry properties have been investigated for 85 MeV C ion beams within the fluence range 2×10⁹-5×10¹² ions/cm². The phosphor exhibits a sublinear dependence against dose for the studied fluence range with no discernible shift in peak position. The favorable outcomes include low fading during the initial days of storage time and batch homogeneity. TL glow curve analysis indicate the formation of trapping level in the range of 0.90-1.72eV within the band gap of the phosphor which are responsible for TL process. The phosphor's simple glow curve structure, minimal fading, consistent batch homogeneity and high stability of the glow curve suggest that the material can be explored for C ion beam dosimetry application.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.6
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• pp.406-413
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• 2012

Effect of three additives, chitosan, ferric chloride, and MPE50 on membrane fouling reduction was studied. They were introduced with various dosing rate into activated sludge, and changes in filtration resistance measured by the batch cell filtration test were evaluated. Both the filtration resistance and the specific cake resistance were minimized at 20 mg/g-MLSS with chitosan, 70 mg/g-MLSS with ferric chloride, and 20 mg/g-MLSS with MPE50 addition, respectively. Introduction of the additives into the activated sludge resulted in reduction of not only cake resistance, but also fouling resistance. However, the chitosan addition to three different activated sludge resulted in three different optimal dose of 10, 20, 30 mg/g-MLSS, respectively. This implies that the optimal dose is dependent on sludge characteristics rather than a constant value. Overdose above the optimal dosage always aggravated filterability in all cases. Zeta potential of sludge flocs, relative hydrophobicity, floc size distribution, soluble EPS concentration and supernatant turbidity were measured in order to analyze fouling reduction mechanism. Nearly neutral surface charge along with the largest particle size was observed at the optimal dose. This could be explained by particle destabilization and restabilization mechanism as positively charged additives were injected into sludge flocs of negative surface charge. Both soluble EPS concentration and supernatant turbidity also showed the lowest value at the optimal dose. These foulants are believed to be coagulated and entrapped in sludge flocs during flocculation. Chitosan and MPE50 which are cationic polymeric substances showed higher reduction in both soluble EPS and fine particles comparing with ferric chloride.