60Co Γ-rays Research Articles

Non-destructive analysis of ancient bimetal swords from western Asia by γ-ray radiography and X-ray fluorescence

Eight ancient bimetal swords held by Hiroshima University, Japan were analyzed non-destructively through γ-ray radiography and X-ray fluorescence (XRF). 137Cs and 60Co γ-ray irradiation sources were used to obtain transmission images of swords. A scanning radiography method using a 60Co γ-ray source was developed. XRF was used for qualitative elemental analysis of the swords. The presence of iron cores in the hilts of some swords had been observed and it was assumed that the cores were a ritual symbol or had a functional purpose. However, our work reveals that these swords were originally bronze-hilted iron swords and that the rusty blades were replaced with bronze blades to maintain the swords’ commercial value as an antique. Consequently, the rest of the iron blade was left in the hilt as an iron tang. The junction of the blade and the guard was soldered and painted to match the patina color. XRF analysis clearly showed that the elemental Sn/Cu ratios of the blades and the hilts were different. These findings are useful for clarifying the later modifications of the swords and are important for interpreting Bronze Age and Iron Age history correctly.

Ionizing radiation effect on single event upset sensitivity of ferroelectric random access memory

The impact of ionizing radiation effect on single event upset (SEU) sensitivity of ferroelectric random access memory (FRAM) is studied in this work. The test specimens were firstly subjected to 60Co γ-ray and then the SEU evaluation was conducted using 209Bi ions. As a result of TID-induced fatigue-like and imprint-like phenomena of the ferroelectric material, the SEU cross sections of the post-irradiated devices shift substantially. Different trends of SEU cross section with elevated dose were also found, depending on whether the same or complementary test pattern was employed during the TID exposure and the SEU measurement.

P 015 - Cellular redox status mediates adaptive response to ionizing radiation in human peripheral blood mononuclear cells

Radioadaptive response refers to the phenomenon where a small priming dose of ionizing radiation (IR) reduces the detrimental effects of subsequent higher IR dose. In this study, we demonstrated that adaptive response in human peripheral blood mononuclear cells (PBMCs) is associated with altered cellular oxidative stress. DNA strand breaks, analysed with comet assay and γH2AX, was used as the endpoint to demonstrate adaptive response in PBMCs exposed to a priming dose of 10 cGy Co60 γ-rays followed by a challenge dose of 2 Gy γ-rays (dose rate 0.3 Gy/min) after 4 hours. Primed cells showed significantly lesser DNA damage accompanied with decreased levels of ROS and increased antioxidant responses. This included changes in the expression for genes like SOD2, GPx, CAT and TRX. In addition, increased activity of enzymatic defense system, mainly SOD and TXNRD, but not CAT and GPx, was observed in the primed cells. These responses were shown to be mediated through increased DNA binding of stress responsive transcription factors Nrf2 and NFκB. The primed cells also showed early activation of ERK, p38 and JNK MAP kinases. Label-free LCMS analysis revealed unique pattern of differentially expressed proteins in the primed cells. A better understanding of adaptive response will contribute towards refinement of radiation protection strategies and radiotherapy protocols.

Toll-like receptor 5 agonist CBLB502 induces radioprotective effects in vitro.

CBLB502 derived from Salmonella flagellin is a novel agonist of Toll-like receptor 5 (TLR5). It has been shown that CBLB502 can exert high radioprotective efficacy on mice and primates from both GI and hematopoietic syndromes during whole-body irradiation with low toxicity and immunogenicity. However, no effective system has been used to investigate the protective effect of CBLB502 against irradiation and the related mechanism in vitro. In this study, we investigated the radioprotective properties of CBLB502 in HEK293-N-T cells constitutively expressing human TLR5 and NF-κB-dependent luciferase. HEK293-N-T cells were treated with different doses of CBLB502 prior to 60Co-γ ray irradiation. After irradiation, cell viability was real-time measured for 4 days by using the real-time cell analysis system. We found that CBLB502 was capable of efficiently maintaining the survival rate of irradiated HEK293-N-T cells. Then apoptotic cell death and cell cycle were detected by flow cytometry. The results showed that CBLB502 pre-treatment could reduce the apoptosis and promote the recovery of irradiated HEK293-N-T cells from G2-phase arrest in a dose-dependent manner. Our data indicated that CBLB502 has a direct radioprotective effect in vitro via anti-apoptosis and promotes cell cycle recovery. The method developed here could be an effective in vitro system to screen other TLR5-target radioprotectants like CBLB502.

Synthesis and thermoluminescence studies of γ-irradiated Dy3+ doped SrGd2O4 phosphor

Dy3+ doped SrGd2O4 phosphors were synthesized via homogeneous precipitation cum auto-combustion method for the first time. Orthorhombic phase formation and granular morphology of SrGd2O4: Dy3+ samples were investigated through X-ray diffraction (XRD) and microscopic studies. Thermoluminescence (TL) characteristics of SrGd2O4: Dy3+ phosphors were taken after exposure of 60Co γ-rays. The TL glow curve of as-prepared phosphors was well-resolved into five peaks 114°C, 161°C, 198°C, 248°C, and 293°C by using computerized glow curve deconvolution program. The effect of impurity (Dy3+) contents and heating rates for the TL glow curves were also studied. The linear behaviour of as-formed SrGd2O4: Dy3+ samples are observed within a wide range of dose of 80Gy–2kGy. Fading characteristics of SrGd2O4: Dy3+ phosphor was studied over the duration of 30days. A comparative study was done to estimate different trapping parameters by employing Chen’s peak shape method and CGCD simulation of TL glow curves.

A study on the degradation of dye-sensitized solar cells irradiated by two different dose rates of γ-rays

This work mainly investigates the radiation effects and the damage mechanism on the dye-sensitized solar cells (DSSCs) irradiated by two dose rates of 60Co γ-rays. Experimental results reveal that the performance of DSSC decreases significantly after irradiation, and the degradation rates of the short circuit current and the maximum power in the high dose rate both outweigh those in the low dose rate at the same adsorbed dose. The γ radiation effects on fluorine-doped tin oxide (FTO) and electrolyte were also studied respectively to investigate the degradation rates of DSSC at different dose rates. The results indicate that the degradation rates are closely relative to concentration of γ irradiation-induced defect on FTO.

Динамика нейромедиаторного обмена у крыс в поздние сроки после облучения γ-квантами 60Co

Динамика нейромедиаторного обмена у крыс в поздние сроки после облучения γ-квантами 60Co

Fabrication of a flexible polycarbonate/porphyrin film dosimeter for high dose dosimetry

Abstract Dyed polycarbonate (PC) Radiochromic films with 20 μm thickness were prepared by casting of organic solution of PC containing 0.5 wt.% tetrakis (pentafluorophenyl) porphyrin (TPPF20) on a glass petri dish. Characterization of the film as a routine dosimeter was studied. On subjecting PC/TPPF20 film dosimeter to gamma radiation, a gradual decrease in the color of films was observed. The sensitivity of these films and the linearity of dose-response curves were studied under 60Co γ-rays expose in dose range of 0–100 kGy. The results were compared with the commercial and non-commercial dosimeters. Experimental parameters including humidity, temperature and pre-irradiation (shelf-life) and post-irradiation storage in dark and in indirect sunlight were examined. The maximum absorbance of soret band of TPPF20 had a bathochromic shift and appeared at 414 nm which remained intact in the investigated dose range. The dyed films characteristics were found to be stable enough in media with high degrees of temperature and humidity. The results indicate that radiation induced decoloration of PC/TPPF20 films can be reliably used in high dose dosimetry.

Transcriptome-based analysis on carbon metabolism of Haematococcus pluvialis mutant under 15% CO2

To elucidate the mechanism underlying the enhanced growth rate in the Haematococcus pluvialis mutated with 60Co-γ rays and domesticated with 15% CO2, transcriptome sequencing was conducted to clarify the carbon metabolic pathways of mutant cells. The CO2 fixation rate of mutant cells increased to 2.57gL−1d−1 under 15% CO2 due to the enhanced photosynthesis, carbon fixation, glycolysis pathways. The upregulation of PetH, ATPF0A and PetJ related to photosynthetic electron transport, ATP synthase and NADPH generation promoted the photosynthesis. The upregulation of genes related to Calvin cycle and ppdK promoted carbon fixation in both C3 and C4 photosynthetic pathways. The reallocation of carbon was also enhanced under 15% CO2. The 19-, 14- and 3.5-fold upregulation of FBA, TPI and PK genes, respectively, remarkably promoted the glycolysis pathways. This accelerated the conversion of photosynthetic carbon to pyruvate, which was an essential precursor for astaxanthin and lipids biosynthesis.

Relative biological effectiveness for photons: implication of complex DNA double-strand breaks as critical lesions

Current knowledge in radiobiology ascribes the adverse biological effects of ionizing radiation primarily to the induction of DNA double-strand breaks (DSBs), which is supposed to be potentially lethal and may be converted to lethal damage due to misrepair. Soft and ultrasoft x-rays have been found to bear elevated biological effectiveness for cell killing compared with conventional x-rays or 60Co γ-rays. This phenomenon is qualitatively interpreted as the increased level of DSB induction for low energy photons, however, a thorough quantitative reasoning is lacking. Here, we systematically compared the relative biological effectiveness (RBE) with relative DSB induction for photons from several hundreds of eV up to MeV. Although there is an approximate two-fold increase in the yields of DSB for low energy photons found in our calculation and a large number of experimental measurements, it is far from enough to account for the three- to four-fold increase in RBE. Further theoretical investigations show that DSB complexity (additional single-strand breaks and base damage within 10 base pairs) increases notably for low energy photons, which largely reconciles the discrepancy between RBE and DSB induction. Our theoretical results are in line with accumulating experimental evidence that complex DSBs are refractory to repair machinery and may contribute predominantly to the formation of lethal damage.

Optimizing the Microscopy Time Schedule for Chromosomal Dosimetry of High-dose and Partial-body Irradiations.

The methodology of cytogenetic triage can be improved by optimizing a schedule of microscopy for different exposure scenarios. Chromosome aberrations were quantified by microscopy in human blood lymphocytes irradiated in vitro to ~2, 4, and 12 Gy acute 60Co γ-rays mixed with the unirradiated blood simulating 10%, 50%, 90%, and 100% exposure and in along with a sample from a homogeneous exposure to ~20 Gy. Biodosimetry workload was statistically modeled assuming that 0.5, 1, 5, or 25 h was available for scoring one case or for analysis of up to 1000 cells or 100 dicentrics plus centric rings by one operator. A strong negative correlation was established between the rates of aberration acquisition and cell recording. Calculations showed that the workload of 1 case per operator per·day (5 h of scoring by microscopy) allows dose estimates with high accuracy for either 90%–100% irradiations of 2 Gy or 50%–90% irradiations of 4–12 Gy; lethal homogeneous (100%) exposures of 12 and 20 Gy can be evaluated with just 1 h of microscopy. Triage analysis of 0.5 h scoring per case results in the minimum tolerable accuracy only for partial- and total-body exposure of 4–20 Gy. Time-related efficacy of conventional biodosimetry depends primarily on the aberration yield in the sample, which is dependent on the radiation dose and its distribution in the patient's body. An optimized schedule of microscopy scoring should be developed for different exposure scenarios in each laboratory to increase their preparedness to radiological emergencies.

Inhibition of Adipogenesis Is Involved in the Protective Effects of 1,25-Dihydroxy Vitamin D3 on the Radiation-Injured Bone Marrow Microenvironment in Mice.

To explore the protective effects of 1,25-dihydroxy vitamin D3 (1,25-(OH)2D3) on the bone marrow microenvironment in mice after irradiation and the underlying molecular mechanisms, a total of 150 7-wk-old male BALB/c mice were randomly divided into a normal group, an irradiation (IR) group and an irradiation+1,25-(OH)2D3 (IR+VD3) group. The mice in the IR+VD3 group were treated with 6.0 Gy 60Coγ rays, and 1,25-(OH)2D3 (dissolved in DMSO, 2.5 μg/kg) was administered once per day from 2 d before to 8 d after irradiation. Mice in the IR group were treated with the same dose of γ rays and an equal volume of DMSO. Subsequently, the body weights and the numbers of peripheral white blood cells (WBCs) were measured. Histological analysis of femur bone marrow was conducted to determine the proportion of adipose area as well. Finally, the expression of peroxisome proliferator-activated receptor-gamma (PPARγ) in bone marrow was detected by immunohistochemistry. After irradiation, the percentage of adipose area in the bone marrow was significantly increased, and the WBC number and body weight were markedly reduced. Compared with irradiation alone, the co-administration of 1,25-(OH)2D3 with irradiation markedly attenuated radiation-induced adipogenesis in bone marrow, resulted in fewer bone marrow stromal cells expressing PPARγ and enhanced the recovery of body weight and WBCs. These results indicate that 1,25-(OH)2D3 could accelerate the recovery of body weight and WBCs in irradiated mice and protect the bone marrow by inhibiting radiation-induced adipogenesis via the down-regulation of PPARγ expression.

Enhanced hydrogen production of Enterobacter aerogenes mutated by nuclear irradiation

Nuclear irradiation was used for the first time to generate efficient mutants of hydrogen-producing bacteria Enterobacter aerogenes, which were screened with larger colour circles of more fermentative acid by-products. E. aerogenes cells were mutated by nuclear irradiation of 60Co γ-rays. The screened E. aerogenes ZJU1 mutant with larger colour circles enhanced the hydrogenase activity from 89.8 of the wild strain to 157.4mLH2/(gDWh). The hereditary stability of the E. aerogenes ZJU1 mutant was certified after over ten generations of cultivation. The hydrogen yield of 301mLH2/gglucose with the mutant was higher by 81.8% than that of 166mL/gglucose with the wild strain. The peak hydrogen production rate of 27.2mL/(L·h) with the mutant was higher by 40.9% compared with that of 19.3mL/(L·h) with the wild strain. The mutant produced more acetate and butyrate but less ethanol compared with the wild strain during hydrogen fermentation.

Mapping of novel powdery mildew resistance gene(s) from Agropyron cristatum chromosome 2P.

A physical map of Agropyron cristatum 2P chromosome was constructed for the first time and the novel powdery mildew resistance gene(s) from chromosome 2P was(were) also mapped. Agropyron cristatum (L.) Gaertn. (2n=28, PPPP), a wild relative of common wheat, is highly resistant to powdery mildew. Previous studies showed that wheat-A. cristatum 2P disomic addition line II-9-3 displayed high resistance to powdery mildew, and the resistance was attributable to A. cristatum chromosome 2P. To utilize and physically map the powdery mildew resistance gene(s), 15 wheat-A. cristatum 2P translocation lines and three A. cristatum 2P deletion lines with different chromosomal segment sizes, obtained from II-9-3 using 60Co-γ ray irradiation, were characterized using cytogenetic and molecular marker analysis. A. cristatum 2P chromosomal segments in the translocations were translocated to different wheat chromosomes, including 1A, 4A, 5A, 6A, 7A, 1B, 2B, 3B, 7B, 3D, 4D, and 6D. A physical map of the 2P chromosome was constructed with 82 STS markers, consisting of nine bins with 34 markers on 2PS and eight bins with 48 markers on 2PL. The BC1F2 populations of seven wheat-A. cristatum 2P translocation lines (2PT-3, 2PT-4, 2PT-5, 2PT-6, 2PT-8, 2PT-9, and 2PT-10) were developed by self-pollination, tested with powdery mildew and genotyped with 2P-specific STS markers. From these results, the gene(s) conferring powdery mildew resistance was(were) located on 2PL bin FL 0.66-0.86 and 19 2P-specific markers were identified in this bin. Moreover, two new powdery mildew-resistant translocation lines (2PT-4 and 2PT-5) with small 2PL chromosome segments were obtained. The newly developed wheat lines with powdery mildew resistance and the closely linked molecular markers will be valuable for wheat disease breeding in the future.

Photocatalytic degradation of ethylene using titanium dioxide nanotube arrays with Ag and reduced graphene oxide irradiated by γ-ray radiolysis

Titanium dioxide nanotube arrays (*TNTAs) made by anodic oxidation method and irradiated under 60Co-γ radiation combining with silver nanoparticles (AgNPs) and reduced graphene oxide (rGO) irradiated by 60Co-γ rays as well were investigated for photocatalytic degradation of ethylene in cold storage environment. Rate constant K of degradation was selected to describe the decomposition efficiency of ethylene with the new photocatalytic composite material (AgNPs/rGO-*TNTAs). Microstructure of the materials as prepared were characterized using analytic techniques: Atomic Force Microscope (AFM), Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscope (TEM), X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). We also compared the performance of five photocatalysts (Thermal annealing TNTAs, *TNTAs, rGO-*TNTAs, AgNPs-*TNTAs, AgNPs/rGO-*TNTAs) concerning ethylene decomposition. Results showed that AgNPs/rGO-*TNTAs exhibited enhancement of photocatalytic degradation of ethylene compared with rGO-*TNTAs and AgNPs-*TNTAs in photocatalytic process. Photocatalytic activity and structural evolution of photocatalysts irradiated by gamma rays and impact of the photocatalysts properties responsible for enhancing photocatalytic activity were discussed.

Morphogenesis and Gene Mapping of deformed interior floral organ 1 (difo1), a Novel Mutant Associated with Floral Organ Development in Rice

Floral organ identity and specific number directly affect anthesis habits, fertilization and grain yield. Here, we identified a deformed interior floral organ 1 (difo1) mutant from selfing progenies of indica cv. Zhonghui8015 (Zh8015) after 60Co γ-ray treatment. Compared with the Zh8015 spikelet, the interior floral organs of the difo1 mutant present various numbers of stamens and stigmas, with no typical filament and no mature pollen grains. Most difo1 flowers exhibited an increased number of stigmas that were attached to the stamens and an intumescent ovule-like cell mass in addition to the ovary. Transverse sections of spikelets and scanning electron microscopy analysis revealed an indeterminate number of interior floral organs and abnormal early spikelet development for the difo1 mutant. Instead of the linear-shaped surface of wild-type stamens, difo1 displayed a glossy stamen surface resulting in immature stamens and complete sterility. In addition, the difo1 mutant exhibited delayed anthesis, rapid anthesis and non-extended stamens compared with wild type. Genetic analysis and gene mapping revealed that difo1 was controlled by a single recessive gene, which was fine-mapped to a 54-kb interval on the short arm of chromosome 4 between markers S22 and RM16439 harboring nine ORFs. Sequence analysis revealed that the mutant carried a single nucleotide deletion in its promoter region, which likely corresponded to the phenotype, in a C2H2-type zinc finger protein gene (LOC_Os04g08600). Moreover, qRT-PCR analysis showed a significantly down-regulated expression pattern for DIFO1 and many floral organ identity genes in the interior floral organs of difo1. DIFO1 is therefore an important floral organ development gene in rice, particularly with regard to interior organ meristem identity and floret primordium differentiation.

Gene expression of immediate early genes of AP-1 transcription factor in human peripheral blood mononuclear cells in response to ionizing radiation.

Ionizing radiation (IR) is considered ubiquitous in nature. The immediate early genes are considered the earliest nuclear targets of IR and are induced in the absence of de novo protein synthesis. Many of these genes encode transcription factors that constitute the first step in signal transduction to couple cytoplasmic effects with long-term cellular response. In this paper, coordinated transcript response of fos and jun family members which constitute activator protein 1 transcription factor was studied in response to IR in human peripheral blood lymphocytes at the G0 stage. Gene expression was monitored 5min, 1h and 4h post-irradiation with Co60 γ-rays (dose rate of 0.417Gy/min) and compared with sham-irradiated controls. When gene expression was analyzed at the early time point of 5min post-irradiation with 0.3Gy, the studied samples showed two distinct trends. Six out of ten individuals (called 'Group I responders') showed transient, but significant up-regulation for fosB, fosL1, fosL2 and c-jun with an average fold change (FC) ≥1.5 as compared to sham-irradiated controls. The Students's t test p value for all four genes was ≤0.001, indicating strong up-regulation. The remaining four individuals (called Group II responders) showed down-regulation for these same four genes. The average FC with 0.3Gy in Group II individuals was 0.53±0.22 (p=0.006) for fosB, 0.60±0.14 (p=0.001) for fosL1, 0.52±0.16 (p=0.001) for fosL2 and 0.59±0.28 (p=0.03) for c-jun. The two groups could be clearly distinguished at this dose/time point using principal component analysis. Both Group I and Group II responders did not show any change in expression for three genes (c-fos, junB and junD) as compared to sham-irradiated controls. Though a similar trend was seen 5min post-irradiation with a relatively high dose of 1Gy, the average FC was lower and change in gene expression was not statistically significant (at p<0.05), except for the down-regulation at fosL2 for Group II individuals (mean FC=0.70±0.15, p=0.008). Both groups of individuals did not show any differential change in expression (FC~1.0) for most loci at the late time points of 1 and 4h, neither with 0.3Gy nor with 1Gy.

Synthesis, Characterization, and Alkaline Stabilities of 4-Vinylimidazolium-Based Anion Conducting Polymer Electrolyte Membranes Prepared By Radiation-Induced Grafting for Alkaline Fuel Cell Applications

There has been a growing interest in noble metal-free alkaline fuel cells, in which anion conducting polymer electrolyte membranes (AEMs) required highly alkaline durability because of high temperature and highly basic fuel cell operating condition in the fuel cells. In recent years, we have developed N-vinylimidazolium-type AEMs by radiation-induced grafting for direct hydrazine hydrate fuel cells (DHFCs).1,2 The prepared poly(N-vinylimidazolium)-grafted AEMs (NVIm-AEM) showed moderate alkaline stability, however, these AEMs degraded via the initial β-elimination at the initial stage and hydrolytic ring opening reaction of the imidazolium unit at the later stage.3 In this work, we synthesized the AEM based on a homo- and co-polymer grafts of 2-methyl-N-methyl-4-vinylimidazolium with styrene (2Me-NMe-4VIm-AEM and 2Me-NMe-4VIm/St-AEM) to prevent the β-elimination and ring opening reaction (Figure 1).According to the literature, 4-vinylimidazole (4VIm) was transformed to N-methyl-4-vinilimidazole (NMe-4VIm) by the N-methylation using sodium hydrate and methyl iodide in a 64% yield.4 NMe-4VIm was then reacted with n-BuLi and methyl iodide to give a 2-methyl-N-methyl-4-vinylimidazole monomer (2Me-NMe-4VIm) in a 56% yield (Scheme 1).The poly(ethylene-co-tetrafluoroethylene) (ETFE) films were irradiated with a 60Co γ-ray source (QST Takasaki, Gunma, Japan) at room temperature in argon atmosphere. The pre-irradiated ETFE films were immediately immersed into the argon-purged monomer solution consisting of 5.3 mol/L 2Me-NMe-4VIm or a mixture of 2Me-NMe-4VIm and St (80 : 20 molar ratio) in 1,4-dioxane. The graft reaction proceeds smoothly and gave 2Me-NMe-4VIm and 2Me-NMe-4VIm/St graft ETFE films with the grafting degree of 33% and 54%, respectively. The grafted films were then N-alkylated and ion exchanged to obtain the hydroxide from of 2Me-NMe-4VIm-AEM and 2Me-NMe-4VIm /St-AEM with IECs of 1.38 and 1.74 mmol/g (Scheme 2). The N-alkylation reaction proceeded quantitatively while the un-methylated analogue, a 4-VIm graft ETFE film, showed less reactivity and saturated at around 66% level. 2Me-NMe-4VIm-AEM and 2Me-NMe-4VIm /St-AEM showed conductivities of 175 and 157 mS/cm with water uptakes of 53 and 86%. These AEMs show significantly higher conductivities with lower water uptakes, which are desirable properties for fuel cell applications.The alkaline stability of AEMs was evaluated by the change in conductivity of AEMs in 1M KOH at 80°C. As shown in Figure 2, the conductivity of NVIm-AEM (N-vinyl type AEM) decreased to 0 mS/cm after 100 h, while 2Me-NMe-4VIm-AEM showed higher conductivities than 20 mS/cm after 100 h. The decreasing profile of the 2Me-NMe-4VIm-AEM conductivity indicates that the initial conductivity drop resulting from β-elimination was clearly suppressed by the shift of vinyl substituent from 1- to 4-positon of the imidazolium ring. Also, the decreases of conductivity at the later period, arising from ring opening degradation become much slower for 2Me-NMe-4VIm-AEM owing to the methyl substitution effect at 2-position of the imidazolium ring. The copolymer type 2Me-NMe-4VIm /St-AEM possesses excellent initial and long term alkaline stabilities. Thus, sharp drops of conductivity at the initial stage probably caused by the graft chain detachment, and the introduction of copolymerized styrene units should suppress the detachment phenomenon by hydrophobicity.5 In conclusion, for vinylimidazolium-containing graft-type AEMs, the control of vinyl position, the methyl-protection at 2-positon, and copolymerization with styrene should be promising strategy to improve the alkaline stability, which is the essential property for alkaline fuel cells.AcknowledgementThis work was supported by the Advanced Low Carbon Technology Research and Development Program (ALCA) from the Japan Science and Technology Agency (JST).

Establishment of Early Endpoints in Mouse Total-Body Irradiation Model.

Acute radiation sickness (ARS) following exposure to ionizing irradiation is characterized by radiation-induced multiorgan dysfunction/failure that refers to progressive dysfunction of two or more organ systems, the etiological agent being radiation damage to cells and tissues over time. Radiation sensitivity data on humans and animals has made it possible to describe the signs associated with ARS. A mouse model of total-body irradiation (TBI) has previously been developed that represents the likely scenario of exposure in the human population. Herein, we present the Mouse Intervention Scoring System (MISS) developed at the Veterinary Sciences Department (VSD) of the Armed Forces Radiobiology Research Institute (AFRRI) to identify moribund mice and decrease the numbers of mice found dead, which is therefore a more humane refinement to death as the endpoint. Survival rates were compared to changes in body weights and temperatures in the mouse (CD2F1 male) TBI model (6–14 Gy, 60Co γ-rays at 0.6 Gy min-1), which informed improvements to the Scoring System. Individual tracking of animals via implanted microchips allowed for assessment of criteria based on individuals rather than by group averages. From a total of 132 mice (92 irradiated), 51 mice were euthanized versus only four mice that were found dead (7% of non-survivors). In this case, all four mice were found dead after overnight periods between observations. Weight loss alone was indicative of imminent succumbing to radiation injury, however mice did not always become moribund within 24 hours while having weight loss >30%. Only one survivor had a weight loss of greater than 30%. Temperature significantly dropped only 2–4 days before death/euthanasia in 10 and 14 Gy animals. The score system demonstrates a significant refinement as compared to using subjective assessment of morbidity or death as the endpoint for these survival studies.

Effects of 56 Fe 17+ , 12 C 6+ heavy-ion and 60 Co γ-ray irradiation in chromosome aberrations, cell cycle and apoptosis of lymphocytes

Objective To compare the radiation effects of 56Fe17+ , 12C6+ ion beams and 60Co γ-rays on chromosome aberrations, cell cycle arrest and apoptosis induction in lymphocytes. Methods Lymphocytes Peng-EBV cells were exposed to 56Fe17+ , 12C6+ ions and 60Co γ-rays with different dose (0, 0.5, 2.0 Gy) at dose rates of 0.26-0.55, 0.30-0.50 and 0.75 Gy/min, respectively. Chromosome aberration and d+ r distortion rate was assayed, and cell apoptosis and cell cycle were analyzed by flow cytometry. Results The percentage of cells with chromosome aberration increased significantly after exposure to12C6+ , 56Fe17+ ion beams and 60Co γ-rays(χ2=12.08-322.9, P<0.05), and the rate of d+ r distortion was significantly increased as well(χ2=4.06-205.37, P<0.05). The chromosome aberration rate and d+ r distortion rateinduced by 56Fe17+ and 12C6+ ion beams were higher than that of γ-rays, especially 12C6+ irradiation. The G2 phase arrest(t=-80.9-0.17, P<0.05)and cell apoptosis(t=-22.65-0.87, P<0.05)were significantly induced by each irradiation in an order of 12C6+ , γ-rays and 56Fe17+ ions from high to low. Conclusions Associated with the LET values, 12C6+ , 56Fe17+ ionbeams and 60Co γ-rays could induce chromosome aberrations, G2 phase arrest and apoptosis in human lymphocytes, where 12C6+ ion beam irradiation was much more effective. Key words: 56Fe17+ ion beam; 12C6+ ion beam; 60Co γ-rays; Chromosome aberrations; Cell apoptosis