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1

Effect of glucocorticoids and gamma radiation on epidermal Langerhans cells  

SciTech Connect

The effect of 750 rads of gamma radiation on the rate of return of epidermal Langerhans cells (LC) following suppressive doses of topical glucorticoids was studied in guinea pigs. Gamma radiation alone had no effect on the LC as assessed by staining for cell membrane ATPase activity and Ia antigen. It did, however, delay the expected return of Ia but not ATPase surface markers on the LC after perturbation with glucocorticoids. The delayed return of surface Ia antigen is possibly related to a radiation-induced defect in the production of a required lymphokine and/or in intracellular Ia transport. Although our data do not rule out a cytolytic effect of steroids on the LC, they do strongly suggest that, at least in part, glucocorticoids act on the LC by altering cell surface characteristics.

Belsito, D.V.; Baer, R.L.; Thorbecke, G.J.; Gigli, I.

1984-02-01

2

Influence on cell proliferation of background radiation or exposure to very low, chronic gamma radiation. [Paramecium tetraurelia; Synechococcus lividus  

SciTech Connect

Investigations carried out on the protozoan Paramecium tetraurelia and the cyanobacteria Synechococcus lividus, which were shielded against background radiation or exposed to very low doses of gamma radiation, demonstrated that radiation can stimulate the proliferation of these two single-cell organisms. Radiation hormesis depends on internal factors (age of starting cells) and external factors (lighting conditions). The stimulatory effect occurred only in a limited range of doses and disappeared for dose rates higher than 50 mGy/y.

Planel, H.; Soleilhavoup, J.P.; Tixador, R.; Richoilley, G.; Conter, A.; Croute, F.; Caratero, C.; Gaubin, Y.

1987-05-01

3

Sensitivity of hyperthermia-treated human cells to killing by ultraviolet or gamma radiation  

SciTech Connect

Human xeroderma pigmentosum (XP) or Fanconi anemia (FA) fibroblasts displayed shouldered 45/sup 0/C heat survival curves not significantly different from normal fibroblasts, a result similar to that previously found for ataxia telangiectasia (AT) cells, indicating heat resistance is not linked to either uv or low-LET ionizing radiation resistance. Hyperthermia (45/sup 0/C) sensitized normal and XP fibroblasts to killing by gamma radiation but failed to sensitize the cells to the lethal effects of 254 nm uv radiation. Thermal inhibition of repair of ionizing radiation lesions but not uv-induced lesions appears to contribute synergistically to cell death. The thermal enhancement ratio (TER) for the synergistic interaction of hyperthermia (45/sup 0/C, 30 min) and gamma radiation was significantly lower in one FA and two strains (TER = 1.7-1.8) than that reported previously for three normal strains (TER = 2.5-3.0). These XP and FA strains may be more gamma sensitive than normal human fibroblasts. Since hyperthermia treatment only slightly increases the gamma-radiation sensitivity of ataxia telangiectasia (AT) fibroblasts compared to normal strains, it is possible that the degree of thermal enhancement attainable reflects the genetically inherent ionizing radiation repair capacity of the cells. The data indicate that both repair inhibition and particular lesion types are required for lethal synergism between heat and radiation. We therefore postulate that the transient thermal inhibition of repair results in the conversion of gamma-induced lesions to irrepairable lethal damage, while uv-type damage can remain unaltered during this period.

Mitchel, R.E.; Smith, B.P.; Wheatly, N.; Chan, A.; Child, S.; Paterson, M.C.

1985-11-01

4

A paracrine signal mediates the cell transformation response to low dose gamma radiation in JB6 cells  

SciTech Connect

Radiation at low doses (? 50 cGy) can enhance or reduce tumor incidence in the mouse skin multistage model of carcinogenesis, depending on the timing of radiation exposure relative to chemical initiator. Here we have used JB6 mouse epidermal cells, an in vitro model of late stage tumor promotion, to evaluate the effects of low dose gamma radiation on cell transformation response. JB6 cells were isolated from the DNA-dependent Protein Kinase (DNA-PK) deficient Balb/c mouse that exhibits an unusually sensitive mammary tumor response to ionizing radiation. Exposure of JB6 cells to low dose (2-20 cGy) gamma radiation increased cell transformation response in a dose- and cell density-dependent fashion. JB6 cells were transfected with a membrane targeted enhanced yellow fluorescent protein (EYFP-membrane) and used as bystander cells in a co-culture model. Co-culture of 10 cGy irradiated JB6 cells with na?ve EYFP-membrane cells resulted in a significant increase in EYFP-expressing colonies, relative to co-cultures of sham exposed P+ cells/na?ve EYFP-membrane cells. In contrast, low dose gamma radiation (20 cGy) reduced tumor promoter (epidermal growth factor; 12-O-tetradecanoyl phorbol-13-acetate)-induced transformation response and cell survival in a clonogenic assay to a comparable extent (40%). Our results demonstrate different selective pressures depending on whether low dose radiation modulated the cell transformation response of irradiated or bystander cells, or whether irradiation occurred in conjunction with tumor promoter treatment. The co-culture system developed here is a promising model to define positive and negative selective pressures induced by low dose radiation in a DNA damage repair deficient context that are relevant to carcinogenesis responses.

Weber, Thomas J.; Siegel, Robert W.; Markillie, Lye Meng; Chrisler, William B.; Lei, Xingye C.; Colburn, Nancy H.

2005-05-01

5

The effects of gamma radiation, UV and visible light on ATP levels in yeast cells depend on cellular melanization.  

PubMed

Previously we have shown that growth of melanized fungi is stimulated by low levels of gamma radiation. The goal of this study was to examine the effects of visible light, UV light, and gamma radiation on the energy level (ATP concentration) in melanized Cryptococcus neoformans cells. Melanized C. neoformans cells as well as non-melanized controls were subjected to visible, UV or gamma radiation, and ATP was quantified by measuring the amount of light emitted by the ATP-dependent reaction of luciferase with luciferin. We found that all three forms of radiation led to a reduction in the ATP levels in melanized C. neoformans cells. This points to a universal melanin-related mechanism underlying observation of ATP decrease in irradiated melanized cells. In contrast, in non-melanized cells visible light led to increase in ATP levels; gamma radiation did not cause any changes while UV exposure resulted in some ATP decrease, however, much less pronounced than in melanized cells. PMID:21944206

Bryan, Ruth; Jiang, Zewei; Friedman, Matthew; Dadachova, Ekaterina

2011-05-07

6

Gamma radiation alters cell cycle and induces apoptosis in p53 mutant E6.1 Jurkat cells.  

PubMed

This study aimed at investigating the effect of gamma radiation with 1.5, 3.0 and 7.5 Gy doses on apoptosis induction, cell cycle alteration and increment of amount of p-ATM (phosphorylated ATM) and p-E2F1 (phosphorylated E2F1) proteins in Jurkat T-lymphoblastoid E6.1 cells. Exposure of human p53 mutant Jurkat cells to gamma radiation resulted in apoptosis, which was detected by luminometric and flow cytometric analysis. Also, phosphorylated ATM (ataxia telangiectasia mutated) and E2F1 (elongation factor) proteins were detected by western blot analysis. Based on luminescence detection data the lethal dose of 7.5 Gy induced cell death 12 h after exposure (p<0.05) while sub-lethal doses of 1.5 and 3.0 Gy induced apoptosis 18 h after exposure (p<0.05). Flow cytometric analysis revealed a G2 arrest 24h after exposure to 3.0 and 7.5 Gy. This arrest was accompanied by cell death with an increasing rate of occurrence up to 72 h after exposure. Western blot analysis showed that 1 h after cell irradiation by 1.5, 3.0 and 7.5 Gy, the amount of p-ATM increased to its maximum rate and remained constant up to 6 h, and then it decreased. Moreover, the amount of phosphorylated E2F1 (Ser-31) increased 2 h after exposure to the same doses and remained constant up to 12 h after irradiation. Survival and cell division of treated Jurkat cells showed a decrease compared to the control group. We believe that ionizing radiation-induced DNA damage activates a p53-independent apoptosis pathway via back-up systems in which the phosphorylation of ATM and E2F1 proteins was involved. Thus, gamma radiation can induce apoptosis and cell cycle alteration in Jurkat cells via a P53-independent pathway. PMID:23079488

Ahmadianpour, Mohammad Reza; Abdolmaleki, Parviz; Mowla, Seyed Javad; Hosseinkhani, Saman

2012-09-23

7

Gamma radiation field intensity meter  

DOEpatents

A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

Thacker, L.H.

1995-10-17

8

Mutant quantity and quality in mammalian cells (A{sub L}) exposed to cesium-137 gamma radiation: Effect of caffeine  

SciTech Connect

We examined the effect of caffeine (1,3,7-trimethylxanthine) on the quantity and quality of mutations in cultured mammalian A{sub L} human-hamster hybrid cells exposed to {sup 137}Cs {gamma} radiation. At a dose (1.5 mg/ml for 16 h) that reduced the plating efficiency (PE) by 20%, caffeine was not itself a significant mutagen, but it increased by approximately twofold the slope of the dose-response curve for induction of S1{sup {minus}} mutants by {sup 137}Cs {gamma} radiation. Molecular analysis of 235 S1{sup {minus}} mutants using a series of DNA probes mapped to the human chromosome 11 in the A{sub L} hybrid cells revealed that 73 to 85% of the mutations in unexposed cells and in cells treated with caffeine alone, {sup 137}Cs {gamma} rays alone or {sup 137}Cs {gamma} rays plus caffeine were large deletions involving millions of base pairs of DNA. Most of these deletions were contiguous with the region of the MIC1 gene at 11p13 that encodes the S1 cell surface antigen. In other mutants that had suffered multiple marker loss, the deletions were intermittent along chromosome 11. These {open_quotes}complex{close_quotes} mutations were rare for {sup 137}Cs {gamma} irradiation (1/63 = 1.5%) but relatively prevalent (23-50%) for other exposure conditions. Thus caffeine appears to alter both the quantity and quality of mutations induced by {sup 137}Cs {gamma} irradiation. 62 refs., 3 figs., 3 tabs.

McGuinness, S.M.; Shibuya, M.L.; Ueno, A.M. [Colorado State Univ., Fort Collins, CO (United States)] [and others

1995-06-01

9

EFFECT OF GAMMA RADIATION ON SOME BIOPHYSICAL PROPERTIES OF RED BLOOD CELL MEMBRANE  

Microsoft Academic Search

The present work aims are to study the radiation effects on the red blood cell membrane from three different but correlated properties: electrical, mechanical and chemical, and to derive useful parameters for the evaluation of radiation effects. AC conductivity of cell suspension was measured in the frequency range 40 kHz to 5 MHz, the osmotic fragility of the membrane and

NABILA S. SELIM; O. S. DESOUKY; SEHAM M. ALI; I. H. IBRAHIM; HODA A. ASHRY

10

Caffeine induces a second wave of apoptosis after low dose-rate gamma radiation of HL-60 cells.  

PubMed

Most cell lines that lack functional p53 protein are arrested in the G(2) phase of the cell cycle due to DNA damage. It was previously found that the human promyelocyte leukemia cells HL-60 (TP53 negative) that had been exposed to ionizing radiation at doses up to 10 Gy were arrested in the G(2) phase for a period of 24 h. The radioresistance of HL-60 cells that were exposed to low dose-rate gamma irradiation of 3.9 mGy/min, which resulted in a pronounced accumulation of the cells in the G(2) phase during the exposure period, increased compared with the radioresistance of cells that were exposed to a high dose-rate gamma irradiation of 0.6 Gy/min. The D(0) value (i.e. the radiation dose leading to 37% cell survival) for low dose-rate radiation was 3.7 Gy and for high dose-rate radiation 2.2 Gy. In this study, prevention of G(2) phase arrest by caffeine (2 mM) and irradiation of cells with low dose-rate irradiation in all phases of the cell cycle proved to cause radiosensitization (D(0)=2.2 Gy). The irradiation in the presence of caffeine resulted in a second wave of apoptosis on days 5-7 post-irradiation. Caffeine-induced apoptosis occurring later than day 7 post-irradiation is postulated to be a result of unscheduled DNA replication and cell cycle progress. PMID:14569403

Vávrová, Jirina; Mareková-Rezácová, Martina; Vokurková, Doris; Szkanderová, Sylva; Psutka, Jan

2003-10-21

11

Pilot study of human recombinant interferon gamma and accelerated hyperfractionated thoracic radiation therapy in patients with unresectable stage IIIA\\/B nonsmall cell lung cancer  

Microsoft Academic Search

Purpose: Gamma interferon has a wide range of properties, including the ability to sensitize solid tumor cells to the effects of ionizing radiation. The North Central Cancer Treatment Group has previously completed pilot studies of accelerated hyperfractionated thoracic radiation therapy (AHTRT) in patients with unresectable Stage IIIA\\/B nonsmall cell lung cancer (NSCLC). This Phase I study was designed to assess

Edward G. Shaw; Richard L. Deming; Edward T. Creagan; Suresh Nair; John Q. Su; Ralph Levitt; Preston D. Steen; Martin Wiesenfeld; James A. Mailliard

1995-01-01

12

Effect of gamma and UV-B\\/C radiation on plant cells  

Microsoft Academic Search

The biological effect of gamma-rays is based on the interaction with atoms or molecules in the cell, particularly water, to produce free radicals, which can damage different important compounds of plant cell. The UV-B\\/C photons have enough energy to destroy chemical bounds, causing a photochemical reaction. The biological effect is due to these processes. This paper is focused on the

E Kovács; Á Keresztes

2002-01-01

13

Cell cycle checkpoint status in human malignant mesothelioma cell lines: response to gamma radiation  

Microsoft Academic Search

Knowledge of the function of the cell cycle checkpoints in tumour cells may be important to develop treatment strategies for human cancers. The protein p53 is an important factor that regulates cell cycle progression and apoptosis in response to drugs. In human malignant mesothelioma, p53 is generally not mutated, but may be inactivated by SV40 early region T antigen (SV40

C Vivo; C Lecomte; F Levy; K Leroy; Y Kirova; A Renier; L Kheuang; P Piedbois; D Chopin; M C Jaurand

2003-01-01

14

Coffee-mediated protective effects against directly acting genotoxins and gamma-radiation in mouse lymphoma cells.  

PubMed

The cytokinesis-block micronucleus test was performed using L5178Y mouse lymphoma cells to ascertain whether or not standard (caffeinated) instant coffee, the commonly consumed polyphenolic beverage with antioxidant activity can protect against chromosomal damage induced by the directly acting agents N-methyl-N-nitro-N-nitrosoguanidine (MNNG), mitomycin C (MMC), methyl methanesulfonate (MMS) and gamma radiation. Our results demonstrated significant reductions in the in vitro genotoxic effects of MNNG, MMC, and MMS following co-treatment of mouse lymphoma cells with standard instant coffee. Subsequently, the comet assay was carried out to assess the effect of coffee co-treatment on the level of DNA damage induced by MMS in mouse lymphoma cells. The results demonstrated a significant reduction in MMS-induced DNA damage following co-treatment with standard instant coffee. Protective effects were observed in mouse lymphoma cells which were treated with coffee immediately after exposure to gamma radiation (1 and 2 Gy). Another experiment showed protection when the mammalian cells were irradiated (0.5 and 1 Gy) midway (at 2 h) during a 4 h coffee treatment. However, the protective effect against the lower dose (0.5 Gy) was not significant. In addition we assessed the modulatory effect of coffee on MNNG-induced apoptotic frequency by flow cytometry. The results revealed only a minor influence of coffee on the frequency of apoptotic cells induced by the test compounds, rendering an increase in sensitivity for apoptosis as a reason for the reduced genomic damage an unlikely or at least incomplete explanation. PMID:15242187

Abraham, S K; Vukicevic, V; Stopper, H

2004-03-01

15

GammaRadiation from Granite  

Microsoft Academic Search

It has been reported that measurements of the ionization produced by the gamma-rays from Quincy granite are in excess of the ionization computed from the measured uranium, thorium, and potassium content of the rock by a factor of over two. It was concluded that either the measured radioactive contents were much too low or that a hitherto unknown penetrating radiation

William D. Urry

1948-01-01

16

Mobilization of progenitor cells into peripheral blood by gamma-tocotrienol: a promising radiation countermeasure.  

PubMed

Gamma-tocotrienol (GT3), a vitamin E isoform, is shown to induce high levels of granulocyte colony stimulating factor (G-CSF) in mice. G-CSF is a key cytokine used for stimulation of hematopoiesis, and mobilization of hematopoietic stem and progenitor cells into peripheral blood. GT3 is also shown to induce vascular endothelial growth factor (VEGF), another important cytokine necessary for vasculogenesis and endothelial progenitor mobilization. Since GT3 induces both these cytokines, we tested whether GT3 mobilizes hematopoietic and endothelial progenitors in mice. GT3 (200mg/kg) was injected in 10-week-old CD2F1 mice and mobilization of progenitors in peripheral blood was analyzed at 24, 48, and 72 h post-administration. Circulating hematopoietic progenitor cells (HPCs, Lin(-), cKit(+)), endothelial progenitor cells (EPCs, Lin(-), CD34(+), Flk(+)), and stromal progenitor cells (SPCs, Lin(-), CD29(+), CD105(+)) in peripheral blood mononuclear cells (PBMCs) were analyzed simultaneously by flow cytometry. Mobilized HPCs, EPCs and SPCs in PBMC were also measured by colony-forming unit (CFU) assay in progenitor-specific media. Three groups of mice received vehicle, GT3 and GT3 plus AMD3100, a receptor antagonist used to enhance mobilization. GT3 induced significant mobilization of all three progenitor cell types compared to vehicle in peripheral blood; AMD3100 enhanced GT3-induced mobilization even further. Mobilization of progenitor cells in peripheral blood by GT3 indicates that GT3 can be used as an alternative to G-CSF and VGEF to mobilize HPCs and EPCs. PMID:23415908

Ray, Sugata; Kulkarni, Shilpa S; Chakraborty, Kushal; Pessu, Roli; Hauer-Jensen, Martin; Kumar, K Sree; Ghosh, Sanchita P

2013-02-12

17

Abdominal {gamma}-Radiation Induces an Accumulation of Function-Impaired Regulatory T Cells in the Small Intestine  

SciTech Connect

Purpose: To assess the frequency and the functional characteristics of one major component of immune tolerance, the CD4{sup +}FoxP3{sup +} regulatory T cells (Tregs) in a mouse model of abdominal irradiation. Methods and Materials: Mice were exposed to a single abdominal dose of {gamma}-radiation (10 Gy). We evaluated small intestine Treg infiltration by Foxp3 immunostaining and the functional suppressive activity of Tregs isolated from mesenteric lymph nodes. Results: Foxp3 immunostaining showed that radiation induced a long-term infiltration of the intestine by Tregs (levels 5.5 times greater than in controls). Co-culture of Tregs from mesenteric lymph nodes with CD4{sup +} effector cells showed that the Tregs had lost their suppressive function. This loss was associated with a significant decrease in the levels of Foxp3, TGF-{beta}, and CTLA-4 mRNA, all required for optimal Treg function. At Day 90 after irradiation, Tregs regained their suppressive activity as forkhead box P3 (Foxp3), transforming growth factor beta (TGF-{beta}), and cytotoxic T-lymphocyte antigen 4 (CTLA-4) expression returned to normal. Analysis of the secretory function of mesenteric lymph node Tregs, activated in vitro with anti-CD3/anti-CD28 Abs, showed that this dysfunction was independent of a defect in interleukin-10 secretion. Conclusion: Radiation caused a long-term accumulation of function-impaired Foxp3{sup +}CD4{sup +} Tregs in the intestine. Our study provides new insights into how radiation affects the immune tolerance in peripheral tissues.

Billiard, Fabienne; Buard, Valerie; Benderitter, Marc [Institut de Radioprotection et de Surete Nucleaire, Direction de la Radioprotection de l'Homme, B.P. no. 17, Fontenay-aux-Roses (France); Linard, Christine, E-mail: christine.linard@irsn.fr [Institut de Radioprotection et de Surete Nucleaire, Direction de la Radioprotection de l'Homme, B.P. no. 17, Fontenay-aux-Roses (France)

2011-07-01

18

Portable gamma and neutron radiation dosimeter reader  

Microsoft Academic Search

During the operation of linear accelerators, gamma and neutron radiation is produced. Gamma radiation causes semiconductor degradation. Therefore, it is necessary to replace electronic devices when the maximum allowed dose is reached to ensure reliable operation of the accelerator. Neutron radiation causes soft errors in memories and registers because of Single Event Upsets (SEUs). This may disturb the whole accelerator

Piotr Krasinski; Dariusz Makowski; Bhaskar Mukherjee

2008-01-01

19

Overexpression of glutamate-cysteine ligase protects human COV434 granulosa tumour cells against oxidative and gamma-radiation-induced cell death.  

PubMed

Ionizing radiation is toxic to ovarian follicles and can cause infertility. Generation of reactive oxygen species (ROS) has been implicated in the toxicity of ionizing radiation in several cell types. We have shown that depletion of the antioxidant glutathione (GSH) sensitizes follicles and granulosa cells to toxicant-induced apoptosis and that supplementation of GSH is protective. The rate-limiting reaction in GSH biosynthesis is catalysed by glutamate-cysteine ligase (GCL), which consists of a catalytic subunit (GCLC) and a regulatory subunit (GCLM). We hypothesized that overexpression of Gclc or Gclm to increase GSH synthesis would protect granulosa cells against oxidant- and radiation-induced cell death. The COV434 line of human granulosa tumour cells was stably transfected with vectors designed for the constitutive expression of Gclc, Gclm, both Gclc and Gclm or empty vector. GCL protein and enzymatic activity and total GSH levels were significantly increased in the GCL subunit-transfected cells. GCL-transfected cells were resistant to cell killing by treatment with hydrogen peroxide compared to control cells. Cell viability declined less in all the GCL subunit-transfected cell lines 1-8 h after 0.5 mM hydrogen peroxide treatment than in control cells. We next examined the effects of GCL overexpression on responses to ionizing radiation. ROS were measured using a redox-sensitive fluorogenic dye in cells irradiated with 0, 1 or 5 Gy of gamma-rays. There was a dose-dependent increase in ROS within 30 min in all cell lines, an effect that was significantly attenuated in Gcl-transfected cells. Apoptosis, assessed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labelling and activated caspase-3 immunoblotting, was significantly decreased in irradiated Gclc-transfected cells compared to irradiated control cells. Suppression of GSH synthesis in Gclc-transfected cells reversed resistance to radiation. These findings show that overexpression of GCL in granulosa cells can augment GSH synthesis and ameliorate various sequelae associated with exposure to oxidative stress and irradiation. PMID:19153097

Cortes-Wanstreet, Mabel M; Giedzinski, Erich; Limoli, Charles L; Luderer, Ulrike

2009-01-18

20

Quantitative proteomic analysis reveals induction of premature senescence in human umbilical vein endothelial cells exposed to chronic low-dose rate gamma radiation.  

PubMed

Chronic low-dose ionizing radiation induces cardiovascular disease in human populations but the mechanism is largely unknown. We suggested that chronic radiation exposure may induce endothelial cell senescence that is associated with vascular damage in vivo. We investigated whether chronic radiation exposure is causing a change in the onset of senescence in endothelial cells in vitro. Indeed, when exposed to continuous low-dose rate gamma radiation (4.1 mGy/h), primary human umbilical vein endothelial cells (HUVECs) initiated senescence much earlier than the nonirradiated control cells. We investigated the changes in the protein expression of HUVECs before and during the onset of radiation-induced senescence. Cellular proteins were quantified using isotope-coded protein label technology after 1, 3, and 6 weeks of radiation exposure. Several senescence-related biological pathways were influenced by radiation, including cytoskeletal organization, cell-cell communication and adhesion, and inflammation. Immunoblot analysis showed an activation of the p53/p21 pathway corresponding to the progressing senescence. Our data suggest that chronic radiation-induced DNA damage and oxidative stress result in induction of p53/p21 pathway that inhibits the replicative potential of HUVECs and leads to premature senescence. This study contributes to the understanding of the increased risk of cardiovascular diseases seen in populations exposed to chronic low-dose irradiation. PMID:23349028

Yentrapalli, Ramesh; Azimzadeh, Omid; Barjaktarovic, Zarko; Sarioglu, Hakan; Wojcik, Andrzej; Harms-Ringdahl, Mats; Atkinson, Michael J; Haghdoost, Siamak; Tapio, Soile

2013-03-04

21

Effects of low-dose radiation on gene expression in Syrian hamster embryo cells: Comparison of JANUS neutrons and gamma rays  

SciTech Connect

Past work by or group and others has shown the modulation of specific genes following exposure of cells to ionizing radiation. Many classes of genes have been found to be modulated in response to ionizing radiation, including those encoding cytoskeletal elements, cell growth arresting proteins, cytokines, and cellular oncogenes. The functions of this specific modulation of gene expression are currently being investigated by several groups: it has been suggested that gene modulation in response to radiation plays a role in the cellular repair of DNA damage, cell survival, or cellular transformation. Several groups have examined induction of nuclear proto-oncogenes following exposure to DNA-damaging agents. In all experiments, we examined modulation of gene expression by ionizing radiations in Syrian hamster embryo (SHE) fibroblasts, which are normal diploid cells that can be neoplastically transformed by low doses of ionizing radiations. Cells plated in 100-mm Petri plates containing 10 ml of medium were irradiated with {sup 60}C {gamma}-rays or fission-spectrum neutrons (0.85 MeV) from the JANUS reactor. All irradiations were performed at 37{degrees}C on cycling cells; equitoxic doses of neutrons and {gamma}-rays were selected on the basis of survival data.

Woloschak, G.E.; Chang-Liu, C.M.

1992-07-01

22

Effects of low-dose radiation on gene expression in Syrian hamster embryo cells: Comparison of JANUS neutrons and gamma rays  

SciTech Connect

Past work by or group and others has shown the modulation of specific genes following exposure of cells to ionizing radiation. Many classes of genes have been found to be modulated in response to ionizing radiation, including those encoding cytoskeletal elements, cell growth arresting proteins, cytokines, and cellular oncogenes. The functions of this specific modulation of gene expression are currently being investigated by several groups: it has been suggested that gene modulation in response to radiation plays a role in the cellular repair of DNA damage, cell survival, or cellular transformation. Several groups have examined induction of nuclear proto-oncogenes following exposure to DNA-damaging agents. In all experiments, we examined modulation of gene expression by ionizing radiations in Syrian hamster embryo (SHE) fibroblasts, which are normal diploid cells that can be neoplastically transformed by low doses of ionizing radiations. Cells plated in 100-mm Petri plates containing 10 ml of medium were irradiated with {sup 60}C {gamma}-rays or fission-spectrum neutrons (0.85 MeV) from the JANUS reactor. All irradiations were performed at 37{degrees}C on cycling cells; equitoxic doses of neutrons and {gamma}-rays were selected on the basis of survival data.

Woloschak, G.E.; Chang-Liu, C.M.

1992-01-01

23

Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture  

SciTech Connect

The countrate response of a gamma spectrometry system from a neutron radiation source behind a plane of moderating material doped with a nuclide of a large radiative neutron capture cross-section exhibits a countrate response analogous to a gamma radiation source at the same position from the detector. Using a planar, surface area of the neutron moderating material exposed to the neutron radiation produces a larger area under the prompt gamma ray peak in the detector than a smaller area of dimensions relative to the active volume of the gamma detection system.

Scott Wilde, Raymond Keegan

2008-07-01

24

Pocket dual Neutron\\/Gamma radiation detector  

Microsoft Academic Search

A pocket radiation detection system has been developed at the INEEL for homeland security applications. It can detect both neutrons and gamma rays instantaneously. This sensor has been designed with an emphasis on compactness' recognizing the widespread need for a radiation detection instrument that could provide both neutron and gamma ray detection in a single, portable unit. It is very

Rahmat Aryaeinejad; David F. Spencer

2003-01-01

25

Pocket dual neutron\\/gamma radiation detector  

Microsoft Academic Search

A pocket radiation detection system has been developed at the Idaho National Engineering and Environmental Laboratory for homeland security applications. It can detect both neutrons and gamma rays instantaneously. This sensor has been designed with an emphasis on compactness, recognizing the widespread need for a radiation detection instrument that could provide both neutron and gamma-ray detection in a single, portable

Rahmat Aryaeinejad; David F. Spencer

2004-01-01

26

Clinical Analysis of stereotactic body radiation therapy using extracranial gamma knife for patients with mainly bulky inoperable early stage non-small cell lung carcinoma  

Microsoft Academic Search

Purpose  To evaluate the clinical efficacy and toxicity of stereotactic body radiation therapy (SBRT) using extracranial gamma knife\\u000a in patients with mainly bulky inoperable early stage non-small cell lung carcinoma (NSCLC).\\u000a \\u000a \\u000a \\u000a \\u000a Materials and methods  A total of 43 medically inoperable patients with mainly bulky Stage I\\/II NSCLC received SBRT using gamma knife were reviewed.\\u000a The fraction dose and the total dose were

Dajun Wu; Hong Zhu; Hanjun Tang; Changlin Li; Feng Xu

2011-01-01

27

Gamma radiation exposure of MCT diode arrays  

Microsoft Academic Search

Investigations of electrical properties of long-wavelength infrared (LWIR) mercury cadmium telluride arrays exposed to gamma-radiation have been performed. Resistance-area product characteristics of LWIR n+-p-photodiodes have been investigated using a microprobe technique at T ap 78 K before and after exposure to various doses of gamma-radiation (Co60 Gammas). The current transport mechanisms for those structures are described within the framework of

F. F. Sizov; I. O. Lysiuk; J. V. Gumenjuk-Sichevska; S. G. Bunchuk; V. V. Zabudsky

2006-01-01

28

Protective Role of Hsp27 Protein Against Gamma Radiation-Induced Apoptosis and Radiosensitization Effects of Hsp27 Gene Silencing in Different Human Tumor Cells  

SciTech Connect

Purpose: The ability of heat shock protein 27 (Hsp27) to protect cells from stressful stimuli and its increased levels in tumors resistant to anticancer therapeutics suggest that it may represent a target for sensitization to radiotherapy. In this study, we investigate the protective role of Hsp27 against radiation-induced apoptosis and the effect of its attenuation in highly expressing radioresistant cancer cell lines. Methods and Materials: We examined clonogenic death and the kinetics of apoptotic events in different tumor cell lines overexpressing or underexpressing Hsp27 protein irradiated with photons. The radiosensitive Jurkat cell line, which does not express Hsp27 constitutively or in response to {gamma}-rays, was stably transfected with Hsp27 complementary DNA. Attenuation of Hsp27 expression was accomplished by antisense or RNAi (interfering RNA) strategies in SQ20B head-and-neck squamous carcinoma, PC3 prostate cancer, and U87 glioblastoma radioresistant cells. Results: We measured concentration-dependent protection against the cytotoxic effects of radiation in Jurkat-Hsp27 cells, which led to a 50% decrease in apoptotic cells at 48 hours in the highest expressing cells. Underlying mechanisms leading to radiation resistance involved a significant increase in glutathione levels associated with detoxification of reactive oxygen species, a delay in mitochondrial collapse, and caspase activation. Conversely, attenuation of Hsp27 in SQ20B cells, characterized by their resistance to apoptosis, sensitizes cells to irradiation. This was emphasized by increased apoptosis, decreased glutathione basal level, and clonogenic cell death. Sensitization to irradiation was confirmed in PC3 and U87 radioresistant cells. Conclusion: Hsp27 gene therapy offers a potential adjuvant to radiation-based therapy of resistant tumors.

Aloy, Marie-Therese [Universite de Lyon 1, Laboratoire de Radiobiologie Cellulaire et Moleculaire, Faculte de Medecine Lyon-Sud, Oullins (France); Hospices Civils de Lyon, Service de Radiotherapie, Centre Hospitalier Lyon-Sud, Pierre-Benite (France)], E-mail: marie-therese.aloy@sante.univ-lyon1.fr; Hadchity, Elie; Bionda, Clara [Universite de Lyon 1, Laboratoire de Radiobiologie Cellulaire et Moleculaire, Faculte de Medecine Lyon-Sud, Oullins (France); Diaz-Latoud, Chantal [Universite de Lyon 1, UMR-CNRS-5534, Centre de Genetique Moleculaire et Cellulaire, Villeurbanne (France); Claude, Line; Rousson, Robert [Universite de Lyon 1, Laboratoire de Radiobiologie Cellulaire et Moleculaire, Faculte de Medecine Lyon-Sud, Oullins (France); Arrigo, Andre-Patrick [Universite de Lyon 1, UMR-CNRS-5534, Centre de Genetique Moleculaire et Cellulaire, Villeurbanne (France); Rodriguez-Lafrasse, Claire [Universite de Lyon 1, Laboratoire de Radiobiologie Cellulaire et Moleculaire, Faculte de Medecine Lyon-Sud, Oullins (France)

2008-02-01

29

Dibasic calcium phosphate dihydrate, USP material compatibility with gamma radiation  

NASA Astrophysics Data System (ADS)

Gamma radiation is a commonly used method to reduce the microbial bioburden in compatible materials when it is applied at appropriate dose levels. Gamma irradiation kills bacteria and mold by breaking down the organism’s DNA and inhibiting cell division. The purpose of this study is to determine the radiation dosage to be used to treat Dibasic Calcium Phosphate Dihydrate, USP (DCPD) and to evaluate its physicochemical effects if any, on this material. This material will be submitted to various doses of gamma radiation that were selected based on literature review and existing regulations that demonstrate that this method is effective to reduce or eliminate microbial bioburden in natural source and synthetic materials. Analytical testing was conducted to the DCPD exposed material in order to demonstrate that gamma radiation does not alter the physicochemical properties and material still acceptable for use in the manufacture of pharmaceutical products. The results obtained through this study were satisfactory and demonstrated that the gamma irradiation dosages from 5 to 30 kGy can be applied to DCPD without altering its physicochemical properties. These are supported by the Assay test data evaluation of lots tested before and after gamma irradiation implementation that show no significant statistical difference between irradiated and non irradiated assay results. The results of this study represent an achievement for the industry since they provide as an alternative the use of Gamma irradiation technology to control the microbial growth in DCPD.

Betancourt Quiles, Maritza

30

Cell engineering: nanometric grafting of poly-N-isopropylacrylamide onto polystyrene film by different doses of gamma radiation.  

PubMed

Poly-N-isopropylacrylamide was successfully grafted onto a polystyrene cell culture dish and ?-preirradiated in air. In this study, the effect of a ?-pre-irradiation dose of radiation (radiation absorbed dosages of 10, 20, 30, 40 KGy) under appropriate temperature and grafting conditions was investigated. The Fourier transform infrared spectroscopy analysis showed the existence of the graft poly-N-isopropylacrylamide (PNIPAAm) on the substrate. The optimal value of the dose for grafting was 40 KGy at 50°C. The scanning electron microscopy and atomic force microscopy (AFM) images clearly showed that increasing the absorbed dose of radiation would increase the amount of grafting. Surface topography and graft thickness in AFM images of the radiated samples showed that the PNIPAAm at the absorbed dose of radiation was properly grafted. The thickness of these grafts was about 50-100 nm. The drop water contact angles of the best grafted sample at 37°C and 10°C were 55.3 ± 1.2° and 61.2 ± 0.9° respectively, which showed the hydrophilicity and hydrophobicity of the grafted surfaces. Differential scanning calorimetry analysis also revealed the low critical solution temperature of the grafted sample to be 32°C. Thermoresponsive polymers were grafted to dishes covalently which allowed fibroblast cells to attach and proliferate at 37°C; the cells also detached spontaneously without using enzymes when the temperature dropped below 32°C. This characteristic proves that this type of grafted material has potential as a biomaterial for cell sheet engineering. PMID:20957116

Biazar, Esmaeil; Zeinali, Reza; Montazeri, Naser; Pourshamsian, Khalil; Behrouz, Mahmoud Jabarvand; Asefnejad, Azadeh; Khoshzaban, Ahad; Shahhosseini, Gholamreza; Najafabadi, Mostafa Soleimannejad; Abyani, Reza; Jamalzadeh, Hamidreza; Fouladi, Mahdi; Hagh, Sasan Rahbar F; Khamaneh, Aylar Shams; Kabiri, Soudabeh; Keshel, Saeed Heidari; Mansourkiaei, Ana

2010-08-09

31

Use of the comet assay to measure DNA damage in cells exposed to photosensitizers and gamma radiation  

NASA Astrophysics Data System (ADS)

We used the comet assay associated with DNA-glycosylases to estimate DNA damage in cells exposed to gamma irradiation or photosensitized either with methylene blue or orange acridine. A calibration performed using irradiation allowed the measurement of the steady-state level and the yield of 8-oxodGuo as well as strand breaks and alkali-labile sites. Nous avons utilisé la méthode des comètes associée à des ADN-glycosylases, pour estimer les dommages de l'ADN dans des cellules après l'exposition à un rayonnement gamma ou après photosensibilisation par le bleu de méthylène ou l'acridine orange. Une calibration de la méthode des comètes a permis de mesurer le niveau basal et les taux de formation de 8-oxodGuo ainsi que le nombre de cassures de brins et de sites alcali labiles.

Pouget, J.-P.; Ravanat, J.-L.; Douki, T.; Richard, M.-J.; Cadet, J.

1999-01-01

32

High range gamma radiation meter  

SciTech Connect

A low power meter has been constructed and tested to measure gamma fields from .1 R/h to 1500 R/h over the energy range of 60 keV to 1.2 MeV. The portable, battery-powered meter consists of a local display unit and remote probe. The display unit indicates gamma intensities via a 4-1/2 digit liquid crystal display (LCD) and a 50-segment bargraph LCD.

Baird, W.; Bjarke, D.; Eisen, Y.

1986-02-01

33

High range gamma radiation meter  

SciTech Connect

A low power meter has been constructed and tested to measure gamma fields from .1 R/hr to 1500 R/hr over the energy range of 60 keV to 1.2 MeV. The portable, battery-powered meter consists of a local display unit and remote probe. The display unit indicates gamma intensities via a 4-1/2 digit liquid crystal display (LCD) and a 50-segment bargraph LCD.

Baird, W.; Bjarke, G.O.; Eisen, Y.

1985-01-01

34

High range gamma radiation meter  

NASA Astrophysics Data System (ADS)

A low power meter has been constructed and tested to measure gamma fields from .1 R/hr to 1500 R/hr over the energy range of 60 keV to 1.2 MeV. The portable, battery-powered meter consists of a local display unit and remote probe. The display unit indicates gamma intensities via a 4-1/2 digit liquid crystal display (LCD) and a 50-segment bargraph LCD.

Baird, W.; Bjarke, G. O.; Eisen, Y.

1985-10-01

35

Balloon-borne telescope for cosmic gamma radiation  

Microsoft Academic Search

The primary gamma radiation could possibly provide information concerning the origin of the cosmic radiation, because gamma rays are not affected by magnetic fields, which have a very pronounced effect on the nucleonic component of the cosmic radiation. In connection with disturbing effects, mainly due to secondary gamma radiation, a minimum altitude of 45 km is required to observe the

H. Rothermel

1976-01-01

36

Biological and electron microscopic changes in gamma radiated Cryptococcus neoformans  

Microsoft Academic Search

Samples ofCryptococcus neoformans were irradiated with various doses of gamma radiation. The relatively low doses, 1–5 × 104 rads, resulted in no obvious effect on the fine structure of the cells but did seriously prevent a large proportion of the organisms from reproducing on agar. When subjected to doses of 1 × 106 rads virtually all the organisms lost their

H. M. Dembitzer; I. Buza; F. Reiss

1972-01-01

37

[Escherichia coli K-12 mutants with enhanced resistance to ionizing radiation. II. Study of DNA damage and repair in gamma-irradiated cells].  

PubMed

Formation and repair of single-stranded breaks (ssb) and double-stranded breaks (dsb) in DNA of gamma-irradiated cells of three Escherichia coli strains (the parental strain AB1157 and radiation-resistant mutants Gamr444 and Gamr445) were studied by centrifugation in alkaline or neutral sucrose gradients. The initial yield of ssb and the kinetics of their repair during post-irradiation incubation in a growth medium are similar for Gamr mutants and the wild-type strain. The yield of dsb in the chromosome of Gamr mutants is significantly lower than in chromosomal DNA of the parental strain, both immediately after gamma-irradiation and after three hours of post-irradiation incubation in a growth medium. The decreased yield of dsb in the Gamr mutants correlates with their relative radioresistance. It was found also that the level of DNA degradation is significantly lower in UV- or gamma-irradiated cells of Gamr mutants, as compared with the wild-type strain. It is suggested that enhanced radioresistance of the Gamr mutants is due to decreased formation of enzymatically induced dsb, as a consequence of moderated DNA degradation under the action of repair exonucleases and also to enhanced efficiency of dsb repair. PMID:6751936

Bresler, S E; Verbenko, V N; Kalinin, V L

1982-01-01

38

Centromere detection in vinblastine- and radiation-induced micronuclei of cytokinesis-blocked mouse cells by using in situ hybridization with a mouse gamma (major) satellite DNA probe  

SciTech Connect

Non-isotopic in situ hybridization using a mouse gamma (major) satellite probe DNA was applied to detect centromeres in micronuclei, which were induced in vitro mouse liver cells by ionizing radiation and by vinblastine sulfate. In a cytokinesis-blocked micronucleus assay a dose-dependent induction of micronuclei was found for both agents. After vinblastine exposure the observed micronuclei showed centromere-positive hybridization signals in an order of magnitude of 70-91%, but after radiation exposure the magnitude was only 10-20%. Since the in situ hybridization technique detects centromeric DNA directly, it can be used in a cytokinesis-blocked micronucleus assay for a rapid and reliable discrimination between aneuploidy-inducing and clastogenic agents.

Salassidis, K.; Huber, R.; Zitzelsberger, H.; Bauchinger, M. (Inst. fuer Strahlenbiologie, Neuherberg (West Germany))

1992-01-01

39

Comparison of repair of DNA double-strand breaks caused by neutron or gamma radiation in cultured human cells.  

PubMed

The dose-response for the induction of initial double-strand breaks (dsb) in DNA of human epithelioid cells by JANUS 0.85 MeV fission-spectrum neutrons was parabolic as assayed by a calibrated neutral filter elution technique. The relative biological effectiveness (RBE) of these neutrons relative to 60Co gamma-rays was unity. The kinetics of repair after a 60 Gy gamma-ray exposure were biphasic. About 65% of these dsb were rapidly repaired (T 1/2 of approximately 2 min), and the remainder were almost completely removed after 150 min at a slower rate (T 1/2 = 30 min). After the same dose of JANUS neutrons, the rapid repair component was markedly reduced (possibly not a significant repair component), and the bulk of the dsb were sealed more slowly (T 1/2 = 90 min). After 150 min, 25% remained unsealed. Even after a lower neutron dose (20 Gy), a proportion of the dsb were refractory to repair. Thus, unrepaired (or irreparable) dsb induced by high energy neutrons might explain the high RBE of neutrons for cell killing. PMID:1682401

Peak, M J; Wang, L; Hill, C K; Peak, J G

1991-12-01

40

Low dose radiation response curves, networks and pathways in human lymphoblastoid cells exposed from 1 to 10cGy of acute gamma radiation.  

PubMed

We investigated the low dose dependency of the transcriptional response of human cells to characterize the shape and biological functions associated with the dose-response curve and to identify common and conserved functions of low dose expressed genes across cells and tissues. Human lymphoblastoid (HL) cells from two unrelated individuals were exposed to graded doses of radiation spanning the range of 1-10cGy were analyzed by transcriptome profiling, qPCR and bioinformatics, in comparison to sham irradiated samples. A set of ?80 genes showed consistent responses in both cell lines; these genes were associated with homeostasis mechanisms (e.g., membrane signaling, molecule transport), subcellular locations (e.g., Golgi, and endoplasmic reticulum), and involved diverse signal transduction pathways. The majority of radiation-modulated genes had plateau-like responses across 1-10cGy, some with suggestive evidence that transcription was modulated at doses below 1cGy. MYC, FOS and TP53 were the major network nodes of the low-dose-response in HL cells. Comparison our low dose expression findings in HL cells with those of prior studies in mouse brain after whole body exposure, in human keratinocyte cultures, and in endothelial cells cultures, indicates that certain components of the low dose radiation response are broadly conserved across cell types and tissues, independent of proliferation status. PMID:21497671

Wyrobek, A J; Manohar, C F; Krishnan, V V; Nelson, D O; Furtado, M R; Bhattacharya, M S; Marchetti, F; Coleman, M A

2011-04-15

41

Low Dose Radiation Response Curves, Networks and Pathways in Human Lymphoblastoid Cells Exposed from 1 to 10 cGy of Acute Gamma Radiation  

SciTech Connect

We investigated the low dose dependency of the transcriptional response of human cells to characterize the shape and biological functions associated with the dose response curve and to identify common and conserved functions of low dose expressed genes across cells and tissues. Human lymphoblastoid (HL) cells from two unrelated individuals were exposed to graded doses of radiation spanning the range of 1-10 cGy were analyzed by transcriptome profiling, qPCR and bioinformatics, in comparison to sham irradiated samples. A set of {approx}80 genes showed consistent responses in both cell lines; these genes were associated with homeostasis mechanisms (e.g., membrane signaling, molecule transport), subcellular locations (e.g., Golgi, and endoplasmic reticulum), and involved diverse signal transduction pathways. The majority of radiation-modulated genes had plateau-like responses across 1-10 cGy, some with suggestive evidence that transcription was modulated at doses below 1 cGy. MYC, FOS and TP53 were the major network nodes of the low-dose response in HL cells. Comparison our low dose expression findings in HL cells with those of prior studies in mouse brain after whole body exposure, in human keratinocyte cultures, and in endothelial cells cultures, indicates that certain components of the low dose radiation response are broadly conserved across cell types and tissues, independent of proliferation status.

Wyrobek, A. J.; Manohar, C. F.; Nelson, D. O.; Furtado, M. R.; Bhattacharya, M. S.; Marchetti, F.; Coleman, M.A.

2011-04-18

42

Mutant quantity and quality in mammalian cells (A{sub L}) exposed to cesium-137 gamma radiation: Effect of caffeine  

Microsoft Academic Search

We examined the effect of caffeine (1,3,7-trimethylxanthine) on the quantity and quality of mutations in cultured mammalian A{sub L} human-hamster hybrid cells exposed to ¹³⁷Cs γ radiation. At a dose (1.5 mg\\/ml for 16 h) that reduced the plating efficiency (PE) by 20%, caffeine was not itself a significant mutagen, but it increased by approximately twofold the slope of the

S. M. McGuinness; M. L. Shibuya; A. M. Ueno

1995-01-01

43

Gamma Radiation Doses In Sweden  

SciTech Connect

Gamma dose rate measurements were performed in one urban and one rural area using thermoluminescence dosimeters (TLD) worn by 46 participants and placed in their dwellings. The personal effective dose rates were 0.096{+-}0.019(1 SD) and 0.092{+-}0.016(1 SD){mu}Sv/h in the urban and rural area, respectively. The corresponding dose rates in the dwellings were 0.11{+-}0.042(1 SD) and 0.091{+-}0.026(1 SD){mu}Sv/h. However, the differences between the areas were not significant. The values were higher in buildings made of concrete than of wood and higher in apartments than in detached houses. Also, {sup 222}Rn measurements were performed in each dwelling, which showed no correlation with the gamma dose rates in the dwellings.

Almgren, Sara; Isaksson, Mats [Department of Radiation Physics, Goeteborg University, Sahlgrenska University Hospital, SE-413 45 Goeteborg (Sweden); Barregaard, Lars [Department of Occupational and Environmental Medicine, Sahlgrenska Hospital and Academy, SE-405 30 Goeteborg (Sweden)

2008-08-07

44

Gamma Radiation Doses In Sweden  

NASA Astrophysics Data System (ADS)

Gamma dose rate measurements were performed in one urban and one rural area using thermoluminescence dosimeters (TLD) worn by 46 participants and placed in their dwellings. The personal effective dose rates were 0.096+/-0.019(1 SD) and 0.092+/-0.016(1 SD)?Sv/h in the urban and rural area, respectively. The corresponding dose rates in the dwellings were 0.11+/-0.042(1 SD) and 0.091+/-0.026(1 SD)?Sv/h. However, the differences between the areas were not significant. The values were higher in buildings made of concrete than of wood and higher in apartments than in detached houses. Also, 222Rn measurements were performed in each dwelling, which showed no correlation with the gamma dose rates in the dwellings.

Almgren, Sara; Barrega?Rd, Lars; Isaksson, Mats

2008-08-01

45

Inspection of cargo containers using gamma radiation  

NASA Astrophysics Data System (ADS)

This paper investigate, with the aid of Monte Carlo simulations and laboratory experiments, a technique for the detection of narcotics in large cargo containers using gamma-radiation. The transmission and back-scattering of photons, at different energies, is used to provide information useful for identifying the presence of bulk quantities of commonly encountered narcotics.

Hussein, Esam M.; Gokhale, Prasad; Arendtsz, Nina V.; Lawrence, Andre H.

1997-02-01

46

Gamma Radiation Tolerance of Magnetic Tunnel Junctions  

NASA Astrophysics Data System (ADS)

Determining the radiation tolerance of magnetic tunnel junctions (MTJ), which are the storage elements of non-volatile magnetoresistive random access memories (MRAM), is important for investigating their potential application in space. In this effort, the effect of gamma radiation on MTJs with MgO tunnel barriers was studied. Experimental and control groups of samples were characterized by ex situ measurements of the magnetoresistive hysteresis loops and I-V curves. The experimental group was exposed to gamma rays from a ^60Co source. The samples initially received a dose of 5.9 Mrad (Si) after which they were again characterized electrically and magnetically. Irradiation was then continued for a cumulative dose of 10 Mrad and the devices re-measured. The result shows no change in magnetic properties such as coercivity or exchange coupling due to irradiation. After correcting for differences in temperature at the time of testing, the tunneling magnetoresistance was also found to be unchanged. Thus, it has been determined that MgO-based MTJs are highly tolerant of gamma radiation, particularly in comparison to silicon field-effect transistors which have been shown to degrade with gamma ray exposure even as low as 100 Krad [Zhiyuan Hu. et al., IEEE trans. on Nucl. Sci., vol. 58, 2011].

Ren, Fanghui; Jander, Albrecht; Dhagat, Pallavi; Nordman, Cathy

2011-10-01

47

Sterilization of teeth by gamma radiation.  

PubMed

Clinical simulations and restorative materials research and development conducted in vitro require the use of large numbers of extracted teeth. The simultaneous need for infection control procedures and minimal alterations of structure and properties of the tissue prompted this study of gamma irradiation as a method to eliminate microbes associated with extracted teeth and their storage solutions. Evaluations of potential change in structure of dentin were conducted in terms of permeability, Fourier transform infrared spectroscopy (FTIR), and optical properties. The dose required for sterilization by gamma irradiation was established by means of a tooth model inoculated with Bacillus subtilis (10(8) organisms/mL). Sterilization occurred at a dose above 173 krad with use of a Cesium (Cs137) radiation source. Gamma irradiation did not affect permeability of crown segments of dentin. A comparative evaluation of the effects of four sterilization methods on dentin disks was based on FTIR and ultraviolet-visible-near infrared (UV/VIS/NIR) spectra before and after sterilization by (1) gamma irradiation; (2) ethylene oxide; (3) dry heat; and (4) autoclaving. No detectable changes were found with gamma irradiation, but all other methods introduced some detectable change in the spectra. This suggests that common methods of sterilization alter the structure of the dentin, but gamma irradiation shows promise as a method which both is effective and introduces no detectable changes as measured by FTIR, UV/VIS/NIR, or permeability. PMID:7929992

White, J M; Goodis, H E; Marshall, S J; Marshall, G W

1994-09-01

48

30 CFR 57.5047 - Gamma radiation surveys.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Gamma radiation surveys. 57.5047 Section 57...METAL AND NONMETAL MINES Air Quality, Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047...

2013-07-01

49

GammaCam{trademark} radiation imaging system  

SciTech Connect

GammaCam{trademark}, a gamma-ray imaging system manufactured by AIL System, Inc., would benefit a site that needs to locate radiation sources. It is capable of producing a two-dimensional image of a radiation field superimposed on a black and white visual image. Because the system can be positioned outside the radiologically controlled area, the radiation exposure to personnel is significantly reduced and extensive shielding is not required. This report covers the following topics: technology description; performance; technology applicability and alternatives; cost; regulatory and policy issues; and lessons learned. The demonstration of GammaCam{trademark} in December 1996 was part of the Large-Scale Demonstration Project (LSDP) whose objective is to select and demonstrate potentially beneficial technologies at the Argonne National Laboratory-East (ANL) Chicago Pile-5 Research Reactor (CP-5). The purpose of the LSDP is to demonstrate that by using innovative and improved decontamination and decommissioning (D and D) technologies from various sources, significant benefits can be achieved when compared to baseline D and D technologies.

NONE

1998-02-01

50

Afterglow Radiation from Gamma Ray Bursts  

SciTech Connect

Gamma-ray bursts (GRB) are huge fluxes of gamma rays that appear randomly in the sky about once a day. It is now commonly accepted that GRBs are caused by a stellar object shooting off a powerful plasma jet along its rotation axis. After the initial outburst of gamma rays, a lower intensity radiation remains, called the afterglow. Using the data from a hydrodynamical numerical simulation that models the dynamics of the jet, we calculated the expected light curve of the afterglow radiation that would be observed on earth. We calculated the light curve and spectrum and compared them to the light curves and spectra predicted by two analytical models of the expansion of the jet (which are based on the Blandford and McKee solution of a relativistic isotropic expansion; see Sari's model [1] and Granot's model [2]). We found that the light curve did not decay as fast as predicted by Sari; the predictions by Granot were largely corroborated. Some results, however, did not match Granot's predictions, and more research is needed to explain these discrepancies.

Desmond, Hugh; /Leuven U. /SLAC

2006-08-28

51

Gamma radiation from the reaction ¹05Pd(p,n. gamma. )¹05Ag  

Microsoft Academic Search

The ..gamma.. radiation from the reaction ¹05Pd(p,n..gamma..)¹05Ag has been studied. To exclude impurity ..gamma.. rays we investigated also the ..gamma.. radiation from the reaction ¹06Pd(p,n..gamma..)¹06Ag. The ..gamma..-ray measurements were made with a Ge(Li) spectrometer with a sensitive volume of 30 cm³ and an energy resolution of 2.8 KeV for a ..gamma..-ray energy 1.3 MeV. As a result of the measurements

R. Mihu; Y. A. Aleksandrov; M. V. Aprelev; P. P. Zarubin

1977-01-01

52

Gamma radiation and gamma protection factors onboard ships during radioactive fallout  

Microsoft Academic Search

Methods of evaluating Gamma Ray Protection Factors (GRPF) for ships in various situations of radioactive fallout are discussed. These factors determine, in connection with a measured gamma radiation dose at a given detector point, the gamma radiation in different compartments of the ship. A computer program GASUFA was developed to calculate the GRPF. GASUFA performs calculations, considering energy, place, and

E. H. Brehm; T. Holst

1975-01-01

53

Reduction of viable cell counts of hospital meals by combination of gamma radiation and other preservative agents  

NASA Astrophysics Data System (ADS)

Frozen vacuum-packed green peas (as a ``vegetable plate'', or, component of meals) was irradiated in the 11-32 kGy dose range and stored at -18°C. Its preparation for eating was performed with microwave heating. After 16 kGy dose, the total viable cell count was less than 10 CFU.g-1, and the count of aerobic spores was under the detection level. The peroxide value did not practically change in the above dose range: it was 38 after 32 kGy dose, and 21 three months later, near to that of the unirradiated sample. The texture was softened by the radiation treatment while the colour did not change significantly. Organoleptic changes were detected by a sensory panel. The off-flavour may be connected with an interaction of the irradiated product and the plastic packaging foil. Processed cheeses (fat content 45%) were vacuum packed and irradiated with 10 and 20 kGy doses at dry-ice temperature. Flavour changes were noted by a majority of the panelists, however, in some cases, the irradiated samples were preferred. This work was partly supported by the IAEA.

Kiss, I. F.; Polyák-Fehér, K.; Farkas, J.; Horti, K.; Beczner, J.; Fábián, A.

1996-09-01

54

Fracture resistance of gamma radiation sterilized cortical bone allografts  

Microsoft Academic Search

Gamma radiation is widely used for sterilization of human cortical bone allografts. Previous studies have reported that cortical bone becomes brittle due to gamma radiation sterilization. This embrittlement raises concern about the performance of a radiation sterilized allograft in the presence of a stress concentration that might be surgically introduced or biologically induced. The purpose of this study was to

Ozan Akkus; Clare M. Rimnac

2001-01-01

55

Radiation Sterilization and Food Irradiation Using Gamma Radiation  

NASA Astrophysics Data System (ADS)

Since the introduction of MDS Nordion's first irradiator in the early 1960's, a variety of gamma-processing systems has been developed. Each design is suited to a particular set of requirements - from high-throughput operations of diverse product lots to full automation or batch processing, all using gamma radiation. Gamma irradiator designs include the Centurion irradiator for temperature-sensitive food products like hamburgers and poultry; the Brevion, a compact batch irradiator providing flexibility, timeliness and simplicity on a whole new scale; a JS-10000 irradiator that operates in either automatic or batch mode to enable multipurpose product scheduling and optimum throughput; and, an irradiator that processes full pallets and is ideal for processing high-density products requiring excellent dose uniformity. These innovative irradiator designs help facilities to be more efficient, maximize operating time, improve product turnaround and minimize inventory levels. MDS Nordion's development of improved Point Kernel and Monte Carlo techniques is discussed, including their application in radiation source optimization, production irradiator design and process control. Absorbed-dose calculations also provide insight into the critical areas for dose mapping and routine monitoring, allowing for the optimum placement of dosimeters. Calculations may also be used to determine the absorbed-dose distribution within product, especially in areas of complex geometry such as material interfaces. The use of easily accessible, accurate and validated dose-calculation programs can be used to optimize the irradiation process. Key Words: dosimetry, irradiator design, dose calculation, modelling, modeling, process control, radiation source optimization.

O'Hara, Kevin

2003-03-01

56

Radiation effects on silver and zinc battery electrodes. I. Interim report, April-July 1965. [. gamma. radiation  

Microsoft Academic Search

During the initial characterization of silver-zinc cell electrodes, and the study of effects of gamma radiation on them, excessive growth of dendrites from the zinc electrode occurred. Therefore, cadmium electrodes were substituted for zinc in this phase of the work. A silver electrode which had a capacity of 0.8 Ah lost 54 mg of material after a gamma dosage of

G. R. Argue; H. L. Recht; W. A. McCollum

1965-01-01

57

Solar Cell Radiation Handbook.  

National Technical Information Service (NTIS)

A method is presented for predicting the degradation of a solar array in a space radiation environment. Solar cell technology which emphasizes the cell parameters that degrade in a radiation environment, is discussed along with the experimental techniques...

J. R. Carter H. Y. Tada

1973-01-01

58

Ultrarelativistic electrons and solar flare gamma-radiation  

NASA Astrophysics Data System (ADS)

Ten solar flares with gamma radiation in excess of 10 MeV were observed. Almost all took place within a heliolatitude greater than 60 deg, close to the solar limb, an indication of the essential anistropy of high-energy gamma radiation. This high-energy solar flare gamma radiation can be explained by the specific features of the bremsstrahlung of ultrarelativistic electrons trapped within the magnetic arc of the solar atmosphere, even if the acceleration of the electrons is anisotropic.

Semukhin, P. E.; Kovaltsov, G. A.

1985-08-01

59

Response of X-ray-sensitive CHO mutant cells to gamma radiation. I. Effects of low dose rates and the process of repair of potentially lethal damage in G1 phase.  

PubMed

X-ray-sensitive CHO mutants (xrs-5 and xrs-6) were exposed to isoleucine-deficient (IL-) medium for 24-36 h to accumulate G1-phase cells. Cells exposed to IL- medium for up to 5 days did not show significant changes in plating efficiency when returned to normal medium. Nearly confluent cultures of IL- -treated cells were irradiated with either 60Co gamma rays (75 cGy/min) or 137Cs gamma rays (2.7, 6.0, or 15.3 cGy/h). A significant reduction (approximately 2.5-fold) in the radiation sensitivity of the parental CHO K-1 cells was observed for chronic low-dose-rate radiation exposure compared to the results obtained for acute high-dose-rate exposure. However, no noticeable differences were observed in the survival curves of either xrs-5 or xrs-6 cells when low-dose-rate and acute exposures were compared. CHO K-1 cells exhibited potentially lethal damage repair while held in IL- medium after gamma irradiation, whereas no repair was observed in either of the radiation-sensitive mutant lines examined at similar survival levels. PMID:2727276

Nagasawa, H; Chen, D J; Strniste, G F

1989-06-01

60

Near ground gamma radiation associated with lightning  

NASA Astrophysics Data System (ADS)

Increases in the atmospheric gamma radiation of 22 to 82above normal background have been observed after the onset of lightning fifteen times since March 2001[1]. Gamma rays have been observed with up to four 12.9 cm3 NaI detectors and recently with a high resolution Ge detector positioned 6-21 m and 15 m above ground, respectively. The tail of the observed background subtracted gamma ray rates GRR were fitted with exponential decay curves yielding typical correlation coefficients of 0.95 to 0.99 and half-lives of 52.7 +/-4.81 min and 52.8+/-10.95 min, without and with precipitation, respectively. The GRR above 300 KeV from radon progeny due to precipitation were subtracted [2]. The 3x3 Ge detector with 2 KeV resolution positioned about 2 m from one of the NaI detectors observed increases in GRR minutes after the onset of lightning with a delayed 50 min exponential decay which was concurrently observed in the NaI detector. [1] M. B. Greenfield et al., Journal of Applied Physics 93 no. 3 (2003) pp 1839-1844. [2] M. B. Greenfield et al., Journal of Applied Physics 93 no. 9 (2003) pp 5733-5741.

Sakuma, K.; Greenfield, M. B.; Ikeda, Y.; Kubo, K.

2004-03-01

61

Gamma Radiation of Textile Waste-Water to Reduce Pollution.  

National Technical Information Service (NTIS)

A two-phase laboratory study of textile waste treatment by gamma radiation from a Cobalt-60 source was conducted. Laboratory prepared dye samples, starch sols, starch desize solutions, and PVA desize solutions were exposed to various dosages of radiation ...

1972-01-01

62

Effects of gamma radiation on chondrogenic development in vitro  

SciTech Connect

Gamma radiation (0.9-8.0 Gy) was used as a perturbing agent to study factors influencing in vitro chondrogenesis of embryonic chick limb bud cell culture. Chondrogenesis was measured using a number of criteria, including (1) cartilage nodule production, (2) spectrophotometric determination of the amount of bound Alcian blue dye, and (3) computer-assisted analysis of the spatial distribution (area) and density of Alcian blue present in individual micromass colonies. Gamma radiation inhibited both cell proliferation and chondrogenesis in a dose- and time-dependent fashion. Administration of benzamide caused a significant increase in cell proliferation at 0.9 and 2.7 Gy, and in chondrogenesis at all doses. Cartilage nodule production was affected during the first 2 days (prior to 48 h) of culture only, suggesting that chondrocytic commitment occurs during this period. Cultures irradiated at 48 and 72 h produced the same number of nodules as controls, but bound significantly less dye, presumably because of decreased cell numbers and/or cell synthesis products. Computer analysis of micromass colonies provided data similar to those collected spectrophotometrically, but displayed the advantages of (1) increased sensitivity to individual variations, (2) the ability to collect data sets without having to pool three or more colonies, and (3) long-term storage of raw images for later analysis.

Garrison, J.C.; Uyeki, E.M.

1988-11-01

63

Effects of low-dose radiation on gene expression in Syrian hamster embryo cells: Comparison of JANUS neutrons and gamma rays  

Microsoft Academic Search

Past work by or group and others has shown the modulation of specific genes following exposure of cells to ionizing radiation. Many classes of genes have been found to be modulated in response to ionizing radiation, including those encoding cytoskeletal elements, cell growth arresting proteins, cytokines, and cellular oncogenes. The functions of this specific modulation of gene expression are currently

G. E. Woloschak; C. M. Chang-Liu

1992-01-01

64

Effect of gamma radiation on honey quality control  

Microsoft Academic Search

Honey is one of the most complex substances produced by bees, mainly from the nectar of flowers. Gamma radiation is a technique that can be used to decrease the number of microbiological problems associated with food and increase the shelf life of certain products. The objective of this study was to verify the effect of gamma radiation with source of

A. Bera; L. B. Almeida-Muradian; S. F. Sabato

2009-01-01

65

Solar Cell Radiation Handbook.  

National Technical Information Service (NTIS)

The handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented. Solar cell theory, cell manufacturing and how they are modeled mathematically are described. The interaction of energetic c...

B. E. Anspaugh H. Y. Tada J. R. Carter R. G. Downing

1982-01-01

66

Effect of. gamma. radiation on sorption properties of polymethylphenylsiloxane films  

SciTech Connect

The effect of ..gamma.. radiation in the 0.01-1 MGy dose range on the capacity of polymethylphenylsiloxane films to sorb water vapors was studied. It was shown that the character of the change in the sorption capacity of the polymer films is a function of the dose of radiation. The results of measurements of the IR spectra were used in discussing the causes of the change in the sorption properties of the films on exposure to ..gamma.. radiation.

Eremina, N.S.; Minakova, T.S.; Komissarova, V.N.

1988-11-01

67

Tolerance induction to a thymus-dependent antigen in vitro: treatment of nonadherent cells with tolerogen biologically filtered in vitro. [Gamma radiation  

Microsoft Academic Search

Highly tolerogenic bovine gamma globulin (BGG), a thymus-dependent antigen, was prepared by biologic filtration in vitro. It readily induced tolerance in vivo in BALB\\/c mice and also rendered their nonadherent lymph node cells tolerant after in vitro incubation. Biologic filtration in vitro was carried out by incubating 2.5 x 10⁷ lymph node cells with 10 mg of nontolerogenic BGG in

J. W. Geyer; Y. M. Kong

1974-01-01

68

A Device for Search of Gamma-Radiation Intensive Sources at the Radiation Accident Condition  

SciTech Connect

The procedure designed for measuring angular distributions of gamma radiation and for search of gamma radiation intensive sources is described. It is based on application of the original multidetector device ShD-1, for measuring an angular distribution in a complete solid angle (4 pi). The calibration results and data on the angular distributions of intensity of gamma radiation at the roof of Chornobyl NPP ''Shelter'' are presented.

Batiy, Valeriy; Klyuchnykov, A; Kochnev, N; Rudko, Vladimir; shcherbin, vladimir; Yegorov, V; Schmieman, Eric A.

2005-08-08

69

Understanding radiation energy and its use in the preservation of seafoods. [X and gamma radiation  

Microsoft Academic Search

Some topics discussed are: the nature of radiation; radiation in the daily routine; penetration of radiation; radiation dosimetry; preservation of food; use of x and gamma radiation for preservation of seafood; and advantages of radiopreservation over heat-processing, freezing, and other methods of preserving seafoods. (HLW)

Ronsivalli

1976-01-01

70

Gamma radiation effects in Yb-doped optical fiber  

NASA Astrophysics Data System (ADS)

Determination of the radiation response of doped-fiber laser materials, systems and components to relevant ionizing radiation fluxes is central to the prediction of long-term fiber-based laser performance/survivability in adverse and/or space-based environments. It is well known that optical elements that are placed into orbit around the Earth experience harsh radiation environments that originate from trapped-particle belts, cosmic rays, and solar events. Of particular interest to optical materials is the continuous flux of gamma photons that the materials encounter. Such radiation exposure commonly leads to the formation of color centers in a broad range of optical materials. Such color center formation gives rise to changes in optical transmission, loss and luminescent band structure, and, thus, impacts long-term optical device performance. In this paper we will present the results of our investigation of gamma-radiation-induced photodarkening on the passive optical transmittance of a number of ytterbium- (Yb-) doped optical fibers. We will discuss the evolution of the optical response of the fiber across the 1.0 to 1.6 micron wavelength window with increasing gamma exposure. Results indicate that these fibers exhibit reasonable radiation resistance to gamma exposures typical of a 5-year, low-earth-orbit environment. Maximum transmittance losses of less than 10% were observed for total gamma exposures of 2-5 krad (Si). In this paper we will present the results of our investigation of gamma-radiation-induced photodarkening on the optical transmittance of a number of ytterbium- (Yb-) doped optical fibers. We will discuss the evolution of the optical response of the fiber across the 1.0 to 1.6 micron wavelength window with increasing gamma exposure. Results indicate that these fibers exhibit reasonable radiation resistance to gamma exposures typical of a 5-year, low-earth orbit environment. Maximum transmittance losses of less than 10% were observed for total gamma exposures of 2-5 krad (Si).

Fox, B. P.; Schneider, Z. V.; Simmons-Potter, K.; Thomes, W. J., Jr.; Meister, D. C.; Bambha, R. P.; Kliner, D. A. V.; Söderlund, M. J.

2007-02-01

71

Modification in dielectric properties: Effect of gamma radiation  

NASA Astrophysics Data System (ADS)

The present paper reports the influence in dielectric properties caused by gamma radiation. The dielectric parameters have been measured for both unirradiated and gamma irradiated 5CB nematic liquid crystal with temperature variation in the frequency range 100 Hz to 10 MHz. Dielectric permittivity with variation in temperature has also been observed. The dielectric permittivity is found to increase for gamma irradiated sample as compared to the unirradiated sample with variation in temperature and frequency and well explained in this paper.

Dixit, Sudhaker; Tripathi, Prachi; Manohar, Rajiv; Arora, A. K.

2013-06-01

72

Inactivation of rabies diagnostic reagents by gamma radiation.  

PubMed Central

Treatment of CVS-11 rabies adsorbing suspensions and street rabies infected mouse brains with gamma radiation resulted in inactivated reagents that are safer to distribute and use. These irradiated reagents were as sensitive and reactive as the nonirradiated control reagents.

Gamble, W C; Chappell, W A; George, E H

1980-01-01

73

Titanium-Water Thermosyphon Gamma Radiation Exposure and Results.  

National Technical Information Service (NTIS)

Titanium-water thermosyphons are being considered for use in heat rejection systems for fission power systems. Their proximity to the nuclear reactor will result in some gamma irradiation. Noncondensable gas formation from radiation-induced breakdown of w...

D. A. Goodenow D. A. Jaworske J. L. A. Sanzi

2012-01-01

74

Design, Construction and Calibration of a Polarimeter for gamma Radiation.  

National Technical Information Service (NTIS)

Information on different nuclear states can be obtained from the analysis of the angular distribution of the emitted gamma radiation. When the information is not sufficient to determine certain relevant parameters, or is ambiguous, a measurement of the li...

A. O. Macchiavelli G. V. Marti C. R. Gimeniz J. A. Laffranchi M. Behar

1980-01-01

75

Tables of Capacitor Discharge in Transient gamma Radiation Environments.  

National Technical Information Service (NTIS)

The tables in this report give the response of various types of capacitors to various transient gamma radiation environments. The tables were generated on the Burroughs B5500 digital computer at Stanford University. The parameters used to characterize the...

D. Landis

1965-01-01

76

Inactivation of rabies diagnostic reagents by gamma radiation  

SciTech Connect

Treatment of CVS-11 rabies adsorbing suspensions and street rabies infected mouse brains with gamma radiation resulted in inactivated reagents that are safer to distribute and use. These irradiated reagents were as sensitive and reactive as the nonirradiated control reagents.

Gamble, W.C.; Chappell, W.A.; George, E.H.

1980-11-01

77

Impact of spectral smoothing on gamma radiation portal alarm probabilities  

Microsoft Academic Search

Gamma detector counts are included in radiation portal monitors (RPM) to screen for illicit nuclear material. Gamma counts are sometimes smoothed to reduce variance in the estimated underlying true mean count rate, which is the “signal” in our context. Smoothing reduces total error variance in the estimated signal if the bias that smoothing introduces is more than offset by the

T. Burr; M. Hamada; N. Hengartner

78

[Effect of continuous gamma-radiation at low doses on clonogenic hemopoietic (CFU-S) and stromal (CFU-F) bone marrow cells ].  

PubMed

We studied the effects of low doses of continuous gamma-irradiation (Co60, 10 days, mean daily dose power 1.5-2.0 mGy, total dose 15 mGy) on hemopoietic and stromal progenitor cells of murine bone marrow. The content of hemopoietic clonogenic cells representing a "younger" (CFU-S-11) and more "mature" (CFU-S-7) categories in the compartment of stem cells was determined in the bone marrow. The state of bone marrow stroma was estimated by the method of in vitro cloning according to the number of progenitor cells that form colonies of fibroblasts (CFU-F) and by the method of ectopic transplantation according to the capacity of stroma of organizing and building new hemopoietic territories. Continuous gamma-irradiation at low doses, that were by one order of magnitude lower than those inducing hermesis, exerted a stimulating effect on both hemopoietic (CFU-S) and stromal (CFU-F) progenitor cells. The number of CFU-S in the compartment of stem cells of the bone marrow markedly increased and they formed larger hemopoietic territories but these cells appeared to create a qualitatively different microenvironment, which stimulated the proliferation of CFU-S. PMID:12180004

Domaratskaia, E I; Starostin, V I; Tsetlin, V V; Butorina, N N; Bueverova, E I; Bragina, E V; Khrushchov, N G

79

77 FR 62267 - Proposed Extension of Existing Information Collection; Gamma Radiation Surveys  

Federal Register 2010, 2011, 2012, 2013

...or solids. Gamma rays penetrate the body and can kill or damage cells in their path which can affect many of the body's organs. The adverse health effects...radiation can vary depending upon the type of cell affected and the extent of...

2012-10-12

80

Integrative proteomic and microRNA analysis of primary human coronary artery endothelial cells exposed to low-dose gamma radiation.  

PubMed

High doses of ionising radiation significantly increase the risk of cardiovascular disease (CVD), the vascular endothelium representing one of the main targets. Whether radiation doses lower than 500 mGy induce cardiovascular damage is controversial. The aim of this study was to investigate radiation-induced expression changes on protein and microRNA (miRNA) level in primary human coronary artery endothelial cells after a single 200 mGy radiation dose (Co-60). Using a multiplex gel-based proteomics technology (2D-DIGE), we identified 28 deregulated proteins showing more than ±1.5-fold expression change in comparison with non-exposed cells. A great majority of the proteins showed up-regulation. Bioinformatics analysis indicated "cellular assembly and organisation, cellular function and maintenance and molecular transport" as the most significant radiation-responsive network. Caspase-3, a central regulator of this network, was confirmed to be up-regulated using immunoblotting. We also analysed radiation-induced alterations in the level of six miRNAs known to play a role either in CVD or in radiation response. The expression of miR-21 and miR-146b showed significant radiation-induced deregulation. Using miRNA target prediction, three proteins found differentially expressed in this study were identified as putative candidates for miR-21 regulation. A negative correlation was observed between miR-21 levels and the predicted target proteins, desmoglein 1, phosphoglucomutase and target of Myb protein. This study shows for the first time that a low-dose exposure has a significant impact on miRNA expression that is directly related to protein expression alterations. The data presented here may facilitate the discovery of low-dose biomarkers of radiation-induced cardiovascular damage. PMID:23138885

Barjaktarovic, Zarko; Anastasov, Natasa; Azimzadeh, Omid; Sriharshan, Arundhathi; Sarioglu, Hakan; Ueffing, Marius; Tammio, Hanna; Hakanen, Arvi; Leszczynski, Dariusz; Atkinson, Michael J; Tapio, Soile

2012-11-09

81

Effect of. gamma. radiation on sorption properties of polymethylphenylsiloxane films  

Microsoft Academic Search

The effect of ..gamma.. radiation in the 0.01-1 MGy dose range on the capacity of polymethylphenylsiloxane films to sorb water vapors was studied. It was shown that the character of the change in the sorption capacity of the polymer films is a function of the dose of radiation. The results of measurements of the IR spectra were used in discussing

N. S. Eremina; T. S. Minakova; V. N. Komissarova

1988-01-01

82

Effect of gamma radiation on microbial safety and nutritional quality of kachri ( Cucumis callosus )  

Microsoft Academic Search

Fresh dried and old (6–12 months) dried kachri (Cucumis callosus) were treated with 0, 2.5, 5 and 7 kGy of gamma radiation in a cobalt 60 gamma cell (GC-1200). The irradiated samples of\\u000a kachri were stored at room temperature (28?±?2 °C). Total bacterial count and nutrient composition were evaluated immediately after\\u000a irradiation and at regular intervals of 1 month during 3 months of storage. Results

N. S. Nathawat; Priyanka Joshi; Brij Gopal Chhipa; Sachin Hajare; Madhu Goyal; M. P. Sahu; Govind Singh

83

Enhancement of natural background gamma-radiation dose around uranium microparticles in the human body  

Microsoft Academic Search

Ongoing controversy surrounds the adverse health effects of the use of depleted uranium (DU) munitions. The biological effects of gamma-radiation arise from the direct or indirect interaction between secondary electrons and the DNA of living cells. The probability of the absorption of X-rays and gamma-rays with energies below about 200 keV by particles of high atomic number is proportional to

John E. Pattison; Richard P. Hugtenburg; Stuart Green

2010-01-01

84

Induction of p53 protein by gamma radiation in lymphocyte lines from breast cancer and ataxia telangiectasia patients  

Microsoft Academic Search

Exposure of human cells to gamma-radiation causes levels of the tumour-suppressor nuclear protein p53 to increase in temporal association with the decrease in replicative DNA synthesis. Cells from patients with the radiosensitive and cancer-prone disease ataxia telangiectasia (AT) exhibit radioresistant DNA synthesis and show a reduced or delayed gamma-radiation-induced increase in p53 protein levels. We have used Western immunoblotting with

GW Birrell; JR Ramsay

1995-01-01

85

Engineering hot-cell windows for radiation protection  

SciTech Connect

Radiation protection considerations in the design and construction of hot-cell windows are discussed. The importance of evaluating the potential gamma spectra and neutron source terms is stressed. 11 references. (ACR)

Ferguson, K.R.; Courtney, J.C.

1983-01-01

86

Gamma and neutrino radiation dose from gamma ray bursts and nearby supernovae.  

PubMed

Supernovae and gamma ray bursts are exceptionally powerful cosmic events that occur randomly in space and time in our galaxy. Their potential to produce very high radiation levels has been discussed, along with speculation that they may have caused mass extinctions noted from the fossil record. It is far more likely that they have produced radiation levels that, while not lethal, are genetically significant, and these events may have influenced the course of evolution and the manner in which organisms respond to radiation insult. Finally, intense gamma radiation exposure from these events may influence the ability of living organisms to travel through space. Calculations presented in this paper suggest that supernovae and gamma ray bursts are likely to produce sea-level radiation exposures of about I Gy with a mean interval of about five million years and sea-level radiation exposures of about 0.2 Gy every million years. Comets and meteors traveling through space would receive doses in excess of 10 Gy at a depth of 0.02 m at mean intervals of 4 and 156 million years, respectively. This may place some constraints on the ability of life to travel through space either between planets or between planetary systems. Calculations of radiation dose from neutrino radiation are presented and indicate that this is not a significant source of radiation exposure for even extremely close events for the expected neutrino spectrum from these events. PMID:11906138

Karam, P Andrew

2002-04-01

87

Effect of gamma radiation on honey quality control  

NASA Astrophysics Data System (ADS)

Honey is one of the most complex substances produced by bees, mainly from the nectar of flowers. Gamma radiation is a technique that can be used to decrease the number of microbiological problems associated with food and increase the shelf life of certain products. The objective of this study was to verify the effect of gamma radiation with source of cobalto-60 (10 kGy) on some parameters used in honey quality control. Seven samples of pure honey were obtained from local markets in Sao Paulo, Brazil, in 2007. The methods used are in accordance with Brazilian Regulations. The physicochemical parameters analyzed were: moisture, HMF, free acidity, pH, sugars and ash. The results showed that gamma radiation, in the dose mentioned above, did not cause significant physicochemical alterations.

Bera, A.; Almeida-Muradian, L. B.; Sabato, S. F.

2009-07-01

88

Nano-Sensitization under gamma rays and fast ion radiation  

NASA Astrophysics Data System (ADS)

The use of heavy compounds to enhance radiation induced damage is a promising approach to improve the therapeutic index of radiotherapy. In order to quantify and control the effects of these radiosensitizers, it is of fundamental interest to describe the elementary processes which take place at the molecular level. Using DNA as a probe, we present a comparison of the damage induced in the presence of platinum compounds exposed to different types of ionizing radiation. We present the results obtained with gamma rays (Linear Energy Transfer (LET) = 0.2 keV.?m-1), fast helium ions He2+ (LET = 2.3 keV.?m-1) and fast carbon ions C6+ (LET = 13 keV.?m-1 and LET = 110 keV.?m-1). The efficiency of two different sensitizers was measured: platinum based molecules (the chloroterpyridine platinum - PtTC) and platinum nanoparticles (PtNP). These experiments show that the two sensitizers are efficiently amplifying molecular damage under photon or ion irradiation. Experiments with a radical scavenger confirmed that these damages are mediated by free radicals for more than 90%. More interestingly, the induction of complex damage, the most lethal for the cells, is amplified by a factor of 1.5 on average if platinum (PtTC and PtNP) is present. As already known, the induction of complex damages increases also with the radiation LET. So, finally, the most significant enhancement of complex damage is observed when ion radiation is combined with platinum induced sensitization.

Porcel, E.; Li, S.; Usami, N.; Remita, H.; Furusawa, Y.; Kobayashi, K.; Le Sech, C.; Lacombe, S.

2012-07-01

89

Impact of spectral smoothing on gamma radiation portal alarm probabilities.  

PubMed

Gamma detector counts are included in radiation portal monitors (RPM) to screen for illicit nuclear material. Gamma counts are sometimes smoothed to reduce variance in the estimated underlying true mean count rate, which is the "signal" in our context. Smoothing reduces total error variance in the estimated signal if the bias that smoothing introduces is more than offset by the variance reduction. An empirical RPM study for vehicle screening applications is presented for unsmoothed and smoothed gamma counts in low-resolution plastic scintillator detectors and in medium-resolution NaI detectors. PMID:21612936

Burr, T; Hamada, M; Hengartner, N

2011-05-17

90

ACUTE EFFECTS OF GAMMA RADIATION IN PRIMATES  

Microsoft Academic Search

One hundred seven Macaca mulatta monkeys were exposed in 16 groups to ; rapid delivery of Co⁶° gamma rays at doses of 400 to 40,000 r. Statistical ; evaluation of the survival time determination of the LD 50\\/30 dose, clinical ; observations for a 30-day postirradiation period, and immediate postmortem ; examinations were performed. These three approaches to the investigation

R. G. Jr. Allen; F. A. Brown; L. C. Logie; D. R. Rovner; S. G. Jr. Wilson; R. W. Zellmer

1959-01-01

91

Effects of gamma Radiation on Peanut Plants.  

National Technical Information Service (NTIS)

The effects of radiation on the time of flowering, time of harvesting, quantity of pods, number of seeds, number of branches, plant height, number of chlorophyl, number of mutated plants, and morphological deformations in Arachis hypospea of Macan variety...

Kumala Dewi H. Muryono

1976-01-01

92

ACUTE EFFECTS OF GAMMA RADIATION IN PRIMATES  

Microsoft Academic Search

One hundred seven small primates were exposed in 16 groups to rapid ; delivery of Co⁶° gamma -rays at doses of 400 to 40,000 r. Statistical ; evaluation of survival times, determination of the LD\\/sub 50(30)\\/ dose, clinical ; observations for a 30day postirradiation period, and immediate postmortem ; examinations were performed. These three approaches to the investigntion of the

R. G. Allen; F. A. Brown; L. C. Logie; D. R. Rovner; S. G. Jr. Wilson; R. W. Zellmer

1960-01-01

93

Haemopoietic cell renewal in radiation fields  

NASA Astrophysics Data System (ADS)

Space flight activities are inevitably associated with a chronic exposure of astronauts to a complex mixture of ionising radiation. Although no acute radiation consequences are to be expected as a rule, the possibility of Solar Particle Events (SPE) associated with relatively high doses of radiation (1 or more Gray) cannot be excluded. It is the responsibility of physicians in charge of the health of astronauts to evaluate before, during and after space flight activities the functional status of haemopoietic cell renewal. Chronic low level exposure of dogs indicate that daily gamma-exposure doses below about 2 cGy are tolerated for several years as far as blood cell concentrations are concerned. However, the stem cell pool may be severely affected. The maintenance of sufficient blood cell counts is possible only through increased cell production to compensate for the radiation inflicted excess cell loss. This behaviour of haemopoietic cell renewal during chronic low level exposure can be simulated by bioengineering models of granulocytopoiesis. It is possible to define a ``turbulence region'' for cell loss rates, below which an prolonged adaptation to increased radiation fields can be expected to be tolerated. On the basis of these experimental results, it is recommended to develop new biological indicators to monitor haemopoietic cell renewal at the level of the stem cell pool using blood stem cells in addition to the determination of cytokine concentrations in the serum (and other novel approaches). To prepare for unexpected haemopoietic effects during prolonged space missions, research should be increased to modify the radiation sensitivity of haemopoietic stem cells (for instance by the application of certain regulatory molecules). In addition, a ``blood stem cell bank'' might be established for the autologous storage of stem cells and for use in space activities keeping them in a radiation protected container.

Fliedner, T. M.; Nothdurft, W.; Tibken, B.; Hofer, E.; Weiss, M.; Kindler, H.

1994-10-01

94

Cytotoxic and interferon gamma-producing activities of gamma delta T cells in the mouse intestinal epithelium are strain dependent.  

PubMed Central

We have analyzed the cytolytic activity of freshly isolated intraepithelial T cells (i-IEL) from the intestines of several different mouse strains in an anti-T-cell receptor monoclonal antibody-mediated redirected lysis assay. The cytolytic activity of gamma delta i-IEL but not that of alpha beta i-IEL was strain dependent. Mouse strains could be divided into high (H), marginal (M), and null (N) strains. The anti-gamma delta T-cell receptor monoclonal antibody-induced interferon gamma production showed the same strain-dependent variability, but the proliferative responses to gamma delta T-cell receptor crosslinking did not show this variability. The N phenotype of gamma delta i-IEL was found to be dominant in (H x N)F1 mice. In radiation bone-marrow chimeras the H/N phenotype was determined by the genotype of the reconstituting bone-marrow-derived cells but was not determined by the genotype of the radioresistant host cells. Analysis of (H x N)F1 backcross animals indicated that at least two genes are involved in determination of the H/N phenotype. One of these genes is major-histocompatibility-complex linked. No difference in the use of the variable region segment of the gamma-chain or delta-chain was seen between the gamma delta i-IEL from H and N strains. Various models that might explain the strain-dependent gamma delta i-IEL phenotypes are discussed.

Ishikawa, H; Li, Y; Abeliovich, A; Yamamoto, S; Kaufmann, S H; Tonegawa, S

1993-01-01

95

Integrated beta and gamma radiation dose calculations for the ferrocyanide waste tanks  

SciTech Connect

This report contains the total integrated beta and gamma radiation doses in all the ferrocyanide waste tanks. It also contains estimated gamma radiation dose rates for all single-shell waste tanks containing a liquid observation well.

Parra, S.A.

1994-11-30

96

The characteristics of solar cells exposed to ?-radiation  

Microsoft Academic Search

We have investigated the characteristics of solar cells exposed to ?-radiation from the standpoint of developing such gamma cells utilizing nuclear spent fuels. The examination was performed for three representative types of solar cells, i.e. amorphous, monocrystalline and polycrystalline types. These solar cells were remotely irradiated using a highly intensive 60Co ?-source instead of spent fuels, and the induced current

Norikazu Horiuchi; Koichi Taniguchi; Masaki Kamiki; Takashi Kondo; Masanori Aritomi

1997-01-01

97

Stability of a salicylate-based poly(anhydride-ester) to electron beam and gamma radiation  

PubMed Central

The effect of electron beam and gamma radiation on the physicochemical properties of a salicylate-based poly(anhydride-ester) was studied by exposing polymers to 0 (control), 25 and 50 kGy. After radiation exposure, salicylic acid release in vitro was monitored to assess any changes in drug release profiles. Molecular weight, glass transition temperature and decomposition temperature were evaluated for polymer chain scission and/or crosslinking as well as changes in thermal properties. Proton nuclear magnetic resonance and infrared spectroscopies were also used to determine polymer degradation and/or chain scission. In vitro cell studies were performed to identify cytocompatibility following radiation exposure. These studies demonstrate that the physicochemical properties of the polymer are not substantially affected by exposure to electron beam and gamma radiation.

Rosario-Melendez, Roselin; Lavelle, Linda; Bodnar, Stanko; Halperin, Frederick; Harper, Ike; Griffin, Jeremy; Uhrich, Kathryn E.

2011-01-01

98

KINETICS OF HYDROGEN PEROXIDE DECOMPOSITION BY $gamma$ RADIATION  

Microsoft Academic Search

Kinetics of the HâOâ decomposition reaction in a wide range ; of aqueous concentrations (2 to 92 mole% HâOâ) under the action of ; gamma radiation were investigated, and comparisons were made of some kinetic ; regularities of thermal and photo-reactions in the same range of concentrations. ; (R.V.J.);

V. Ya. Chernykh; S. Ya. Pshezhetskii; G. S. Tyurikov

1957-01-01

99

GAMMA RADIATION TREATMENT OF WATERS FROM LIGNITE MINES  

EPA Science Inventory

Discussed in this report are results of laboratory investigations carried out with the application of gamma radiation for the purification of waters drained from surface lignite mines. These waters are polluted to a considerable extent with suspended matter of various sizes, a la...

100

Observation of D(1285) -> phi gamma Radiative Decay.  

National Technical Information Service (NTIS)

The D(1285) radiative decay has been observed, 19+- events of this type have been detected. The branching ratio BR(D(1285) -> phi gamma )=(23+-5+-10) keV have been determined. The conclusion has been made that, most probably, the E(1420) meson does not be...

S. I. Bityukov G. V. Borisov V. A. Dorofeev

1987-01-01

101

POLYMERIZATION OF VINYL CHLORIDE UNDER EFFECT OF $gamma$RADIATION  

Microsoft Academic Search

Experiments were conducted on the polymerization of technical vinyl ; chloride under the effect of gamma radiation at with an activity of 18,000 g-; equiv Ra was used as the source. Ths polymerization kinetics was shown to obey ; the general laws governing free radical polymerization. There is a considerable ; induction period, because the initial radicals react with inhibiting

L. D. Bubis; V. L. Karpov; Yu. M. Malinskii; D. M. Yanovskii

1962-01-01

102

THE RESISTANCE TO $gamma$ RADIATION OF THE WORKER BEE  

Microsoft Academic Search

The worker bee which has been subjected to gamma radiation from a Co\\/; sup 60\\/ source can withstand without apparent physical damage a dose of 18,000 r. ; At 90,000 r there is, however, appreciable damage. At a dose of 200,000 r, death ; is immediate in 100% of the cases. The physiological state of the bee plays an ;

G. Courtois; J. Lecomte

1959-01-01

103

Bioburden assessment and gamma radiation inactivation patterns in parchment documents  

NASA Astrophysics Data System (ADS)

Parchment documents are part of our cultural heritage and, as historical artifacts that they are, should be preserved. The aim of this study was to validate an appropriate methodology to characterize the bioburden of parchment documents, and to assess the growth and gamma radiation inactivation patterns of the microbiota present in that material. Another goal was to estimate the minimum gamma radiation dose (Dmin) to be applied for the decontamination of parchment as an alternative treatment to the current toxic chemical and non-chemical decontamination methods. Two bioburden assessment methodologies were evaluated: the Swab Method (SM) and the Destructive Method (DM). The recovery efficiency of each method was estimated by artificial contamination, using a Cladosporium cladosporioides spore suspension. The parchment samples' microbiota was typified using morphological methods and the fungal isolates were identified by ITS-DNA sequencing. The inactivation pattern was assessed using the DM after exposure to different gamma radiation doses, and using C. cladosporioides as reference. Based on the applied methodology, parchment samples presented bioburden values lower than 5×103 CFU/cm2 for total microbiota, and lower than 10 CFU/cm2 for fungal propagules. The results suggest no evident inactivation trend for the natural parchment microbiota, especially regarding the fungal community. A minimum gamma radiation dose (Dmin) of 5 kGy is proposed for the decontamination treatment of parchment. Determining the minimal decontamination dose in parchment is essential for a correct application of gamma radiation as an alternative decontamination treatment for this type of documents avoiding the toxicity and the degradation promoted by the traditional chemical and non-chemical treatments.

Nunes, Inês; Mesquita, Nuno; Cabo Verde, Sandra; Carolino, Maria Manuela; Portugal, António; Botelho, Maria Luísa

2013-07-01

104

Repression of PTEN phosphatase by Snail1 transcriptional factor during gamma radiation-induced apoptosis  

Microsoft Academic Search

The product of the Snail1 gene is a transcriptional repressor required for triggering the epithelial-to-mesenchymal transition. Furthermore, ectopic expression of Snail1 in epithelial cells promotes resistance to apoptosis. In this study, we demonstrate that this resistance to gamma radiation-induced apoptosis caused by Snail1 is associated with the inhibition of PTEN phosphatase. In MDCK cells, mRNA levels of the p53 target

Sandra Peiro; Nicolas Herranz; Patricia Villagrasa; Natalia Dave; Sentis B Montserrat; Stephen A. Murray; C. Franci; Thomas Gridley; Ismo Virtanen; de Herreros Garcia

2008-01-01

105

Fracture resistance of gamma radiation sterilized cortical bone allografts.  

PubMed

Gamma radiation is widely used for sterilization of human cortical bone allografts. Previous studies have reported that cortical bone becomes brittle due to gamma radiation sterilization. This embrittlement raises concern about the performance of a radiation sterilized allograft in the presence of a stress concentration that might be surgically introduced or biologically induced. The purpose of this study was to investigate the effect of gamma radiation sterilization on the fracture resistance of human femoral cortical bone in the presence of a stress concentration. Fracture toughness tests of specimens sterilized at a dose of 27.5 kGy and control specimens were conducted transverse and longitudinal to the osteonal orientation of the bone tissue. The formation of damage was monitored with acoustic emission (AE) during testing and was histologically observed following testing. There was a significant decrease in fracture toughness due to irradiation in both crack growth directions. The work-to-fracture was also significantly reduced. It was observed that the ability of bone tissue to undergo damage in the form of microcracks and diffuse damage was significantly impaired due to radiation sterilization as evidenced by decreased AE activity and histological observations. The results of this study suggest that, for cortical bone irradiated at 27.5 kGy, it is easier to initiate and propagate a macrocrack from a stress concentration due to the inhibition of damage formation at and near the crack tip. PMID:11562143

Akkus, O; Rimnac, C M

2001-09-01

106

Cell Effects of Electromagnetic Radiation  

Microsoft Academic Search

The effects of electromagnetic radiation on cells and cell organelles are reviewed. The original results of studies of the influence of monochrome and impulse radiation on human cells are presented. The heterochromatin granule quantity was investigated as a parameter indicating the state of human cell. It was shown that heterochromatin granule quantity and cell membrane permeability increases under the influence

Y. G. Shckorbatov; N. N. Kolchigin; V. A. Grabina; V. N. Pasiuga; O. V. Kazansky

2006-01-01

107

Gamma-irradiated onions as a biological indicator of radiation dose.  

PubMed

Post-irradiation identification and dose estimation are required to assess the radiation-induced effects on living things in any nuclear emergency. In this study, radiation-induced morphological/cytological changes i.e., number of root formation and its length, shooting length, reduction in mitotic index, micronuclei formation and chromosomal aberrations in the root tip cells of gamma-irradiated onions at lower doses (50-2000 cGy) are reported. The capabilities of this biological species to store the radiation-induced information are also studied. PMID:11762393

Vaijapurkar, S G; Agarwal, D; Chaudhuri, S K; Senwar, K R; Bhatnagar, P K

2001-10-01

108

Fluid metabolism changes in the presence of various forms of acute radiation sickness. [Rats, gamma radiation  

Microsoft Academic Search

Acute radiation sickness was induced in rats by 700 to 1000 R doses of gamma radiation. Fluid metabolism was examined 24, 48 and 72 h later. A table is presented to show changes in total extracellular, intracellular, and intravascular fluid levels. One day after irradiation there was a decrease in total fluid content, intracellular, and intravascular fluid, and an increase

N. I. Tsyran; A. A. Sveshnikov; V. S. Nesterenko

1977-01-01

109

Semiconductors in the nuclear weapon gamma radiation environment. I - Prediction of gamma radiation effects. II - Verification of predictions  

NASA Astrophysics Data System (ADS)

The effects of gamma radiation on the performance of MOS and NMOS devices is considered. The different methods used to predict the ability of an IC to survive a hostile nuclear environment are described including latch-up analysis and topographic analysis. A formula is derived for predicting the failure probability of an IC in relation to the radiation dose in rads. The design of a linear accelerator radiation simulator for testing semiconductor devices is described, and the results of recent calibration tests are presented.

Edwards, A. R.; Hardman, M. A.; Williamson, R.

110

Development of a qualitative dose indicator for gamma radiation using lyophilized Deinococcus.  

PubMed

The feasibility of using Deinococcus showing strong resistance to both desiccation and ionizing radiation as a dose indicator of gamma radiation exposure was evaluated. Three Deinococcus strains having different levels of radiation resistance, Deinococcus radiodurans (DRD), Deinococcus radiopugnans (DRP), and the DRD pprI mutant (DRM), were selected to develop an appropriate dose indicator for a broad range of exposures. DRD, DRP, and DRM cultures with different numbers of cells [~10(7) to 10(3) colony forming units (CFU)/100 microliter] were lyophilized and subjected to various doses of gamma radiation to determine a critical dose that inhibited bacterial growth completely. Finally, a combination of DRD at ~10(7) and ~10(6) CFU, DRP at ~10(5) CFU, and DRM at ~10(4) CFU successfully indicated exposure to 5, 10, 20, and 30 kGy of gamma radiation, respectively. This study shows the possibility of developing a qualitative indicator of radiation exposure using Deinococcus. PMID:22814506

Lim, Sangyong; Song, Dusup; Joe, Minho; Kim, Dongho

2012-09-01

111

Characterization of an Escherichia coli mutant (radB101) sensitive to. gamma. and uv radiation, and methyl methanesulfonate  

SciTech Connect

After N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis of Escherichia coli K-12 (xthA14), an X-ray-sensitive mutant was isolated. This sensitivity is due to a mutation, radB101, which is located at 56.5 min on the E.coli K-12 linkage map. The radB101 mutation sensitized wild-type cells to ..gamma.. and uv radiation, and to methyl methanesulfonate. When known DNA repair-deficient mutants were ranked for their ..gamma..-radiation sensitivity relative to their uv-radiation sensitivity, their order was (starting with the most selectively ..gamma..-radiation-sensitive strain): recB21, radB101, wild type, polA1, recF143, lexA101, recA56, uvrD3, and uvrA6. The radB mutant was normal for ..gamma..- and uv-radiation mutagenesis, it showed only a slight enhancement of ..gamma..- and uv-radiation-induced DNA degradation, and it was approx. 60% deficient in recombination ability. The radB gene is suggested to play a role in the recA gene-dependent (Type III) repair of DNA single-strand breaks after ..gamma.. irradiation and in postreplication repair after uv irradiation for the following reasons: the radB strain was normal for the host-cell reactivation of ..gamma..- and uv-irradiated bacteriophage lambda; the radB mutation did not sensitize a recA strain, but did sensitize a polA strain to ..gamma.. and uv radiation; the radB mutation sensitized a uvrB strain to uv radiation.

Sargentini, N.J.; Smith, K.C.

1983-03-01

112

Characterization of an Escherichia coli mutant (radB101) sensitive to gamma and uv radiation, and methyl methanesulfonate.  

PubMed

After N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis of Escherichia coli K-12 (xthA14), and X-ray-sensitive mutant was isolated. This sensitivity is due to a mutation, radB101, which is located at 56.5 min on the E. coli K-12 linkage map. The radB101 mutation sensitized wildtype cells to gamma and uv radiation, and to methyl methanesulfonate. When known DNA repair-deficient mutants were ranked for their gamma-radiation sensitivity relative to their uv-radiation sensitivity, their order was (starting with the most selectively gamma-radiation-sensitive strain): recB21, radB101, wild type, polA1, recF143, lexA101, recA56, uvrD3, and uvrA6. The radB mutant was normal for gamma- and uv-radiation mutagenesis, it showed only a slight enhancement of gamma- and uv-radiation-induced DNA degradation, and it was approximately 60% deficient in recombination ability. The radB gene is suggested to play a role in the recA gene-dependent (Type III) repair of DNA single-strand breaks after gamma irradiation and in postreplication repair after uv irradiation for the following reasons; the radB strain was normal for the host-cell reactivation of gamma- and uv-irradiated bacteriophage lambda; the radB mutation did not sensitize a recA strain, but did sensitize a polA strain to gamma and uv radiation; the radB mutation sensitized a uvrB strain to uv radiation. PMID:6344125

Sargentini, N J; Smith, K C

1983-03-01

113

Radiation effects on membranes - 1. Cellular permeability and cell survival  

SciTech Connect

The effect of various doses of ..gamma.. radiation (5-60 krad) on the membrane permeability and cell survival of Candida albicans, a pathogenic yeast, was investigated. A reduction in the cell survival and in the accumulation of amino acids (proline, glycine, lysine, and glutamic acid) was observed following irradiation. The rate of oxygen uptake, which is often associated with transport, was also reduced. There was no damage to available sulfhydryl groups following the exposure of cells to various doses of ..gamma.. radiation. The membrane lipid composition of C. albicans cells can be altered by growing them in alkanes of varying chain lengths. The effects of such altered lipid composition on radiosensitivity was examined. It was observed that C. albicans cells with altered lipid content acquire resistance to ..gamma.. radiation.

Khare, S.; Jayakumar, A.; Trivedi, A.; Kesavan, P.C.; Prasad, R.

1982-05-01

114

Curcumin Regulates Low-Linear Energy Transfer {gamma}-Radiation-Induced NF{kappa}B-Dependent Telomerase Activity in Human Neuroblastoma Cells  

SciTech Connect

Purpose: We recently reported that curcumin attenuates ionizing radiation (IR)-induced survival signaling and proliferation in human neuroblastoma cells. Also, in the endothelial system, we have demonstrated that NF{kappa}B regulates IR-induced telomerase activity (TA). Accordingly, we investigated the effect of curcumin in inhibiting IR-induced NF{kappa}B-dependent hTERT transcription, TA, and cell survival in neuroblastoma cells. Methods and Materials: SK-N-MC or SH-SY5Y cells exposed to IR and treated with curcumin (10-100 nM) with or without IR were harvested after 1 h through 24 h. NF{kappa}B-dependent regulation was investigated either by luciferase reporter assays using pNF{kappa}B-, pGL3-354-, pGL3-347-, or pUSE-I{kappa}B{alpha}-Luc, p50/p65, or RelA siRNA-transfected cells. NF{kappa}B activity was analyzed using an electrophoretic mobility shift assay and hTERT expression using the quantitative polymerase chain reaction. TA was determined using the telomerase repeat amplification protocol assay and cell survival using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltertrazolium bromide and clonogenic assay. Results: Curcumin profoundly inhibited IR-induced NF{kappa}B. Consequently, curcumin significantly inhibited IR-induced TA and hTERT mRNA at all points investigated. Furthermore, IR-induced TA is regulated at the transcriptional level by triggering telomerase reverse transcriptase (TERT) promoter activation. Moreover, NF{kappa}B becomes functionally activated after IR and mediates TA upregulation by binding to the {kappa}B-binding region in the promoter region of the TERT gene. Consistently, elimination of the NF{kappa}B-recognition site on the telomerase promoter or inhibition of NF{kappa}B by the I{kappa}B{alpha} mutant compromises IR-induced telomerase promoter activation. Significantly, curcumin inhibited IR-induced TERT transcription. Consequently, curcumin inhibited hTERT mRNA and TA in NF{kappa}B overexpressed cells. Furthermore, curcumin enhanced the IR-induced inhibition of cell survival. Conclusions: These results strongly suggest that curcumin inhibits IR-induced TA in an NF{kappa}B dependent manner in human neuroblastoma cells.

Aravindan, Natarajan, E-mail: naravind@ouhsc.ed [Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK (United States); Veeraraghavan, Jamunarani; Madhusoodhanan, Rakhesh; Herman, Terence S. [Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK (United States); Natarajan, Mohan [Department of Otolaryngology, Head and Neck Surgery, University of Texas Health Sciences Center at San Antonio, San Antonio, TX (United States)

2011-03-15

115

Cutaneous gamma/delta T-cell lymphoma  

PubMed Central

Summary Only 40 cases of primary cutaneous gamma/delta T-cell lymphoma (GD-TCL) have been described. GD-TCL was included as a provisional entity in the WHO-EORTC classification of cutaneous lymphomas in 2005. GD-TCL often failed to respond to polychemotherapy and radiation therapy and have a poor prognosis with a mean survival of only 15 months. We present a patient treated with surgery, immunomodulatory therapy, and polychemotherapy. He then received hematopoietic stem cell transplantation and has been in complete remission since. Allogeneic stem cell transplantation appears to be a promising therapeutic option for aggressive and generally fatal lymphomas like GD-TCL.

Koch, Richard; Jaffe, Elaine S.; Mensing, Christian; Zeis, Matthias; Schmitz, Norbert; Sander, Christian A.

2012-01-01

116

Cutaneous gamma/delta T-cell lymphoma.  

PubMed

Only 40 cases of primary cutaneous gamma/delta T-cell lymphoma (GD-TCL) have been described. GD-TCL was included as a provisional entity in the WHO-EORTC classification of cutaneous lymphomas in 2005. GD-TCL often failed to respond to polychemotherapy and radiation therapy and have a poor prognosis with a mean survival of only 15 months. We present a patient treated with surgery, immunomodulatory therapy, and polychemotherapy. He then received hematopoietic stem cell transplantation and has been in complete remission since. Allogeneic stem cell transplantation appears to be a promising therapeutic option for aggressive and generally fatal lymphomas like GD-TCL. PMID:19694889

Koch, Richard; Jaffe, Elaine S; Mensing, Christian; Zeis, Matthias; Schmitz, Norbert; Sander, Christian A

2009-12-01

117

Protection effects of condensed bromoacenaphthylene on radiation deterioration of ethylene-propylene-diene rubber. [Gamma radiation  

Microsoft Academic Search

As a continuation of a series of the studies on the flame and ..gamma..-radiation resistant modification of ethylene-propylene-diene rubber (EPDM), condensed bromoacenaphthylene (con-BACN) as a newly developed flame retardant was synthesized and its effects on the radiation resistance of EPDM were investigated. The radiation resistance evaluated by measuring tensile properties of irradiated sheets of 2 mm thick was found improved

Y. Morita; M. Hagiwara; N. Kasai

1982-01-01

118

Quality assurance of environmental gamma radiation monitoring in Slovenia.  

PubMed

Environmental gamma radiation monitoring established in Slovenia consists of a network of multifunctional gamma monitors (MFMs) based on pairs of Geiger-Müller counters and a network of measuring sites with high-sensitive thermoluminiscence dosemeters. The measuring points are evenly spread across Slovenia, located at the meteorological stations and more densely on additional locations around the Krsko NPP. The MFM network has a 2-fold function with one sensor used for the purpose of early warning system in near surroundings of the NPP and the other, more sensitive, for natural radiation monitoring. The paper summarises activities to establish quality assurance of the environmental gamma radiation measurements in Slovenia, with a critical view of the results in comparison with the international standards and recommendations. While the results of linearity and energy dependence tests were satisfying, on-field intercomparison showed that the inherent signal of one of the monitors (MFM) has to be taken into account in the range of environmental background radiation. PMID:16410289

Stuhec, M; Zorko, B; Miti?, D; Miljani?, S; Ranogajec-Komor, M

2006-01-12

119

Radiation response of cell organelles  

Microsoft Academic Search

The cellular responses to various form of radiation, including ionizing- and UV-irradiation or exposure to electromagnetic fields is manifested as irreversible and reversible structural and functional changes to cells and cell organelles. Moreover, beside the morphological signs related to cell death, there are several reversible alterations in the structure of different cell organelles. The radiation-induced changes in the supramolecular organization

Z. Somosy

2000-01-01

120

Gamma Radiation Induces Micronucleated Reticulocytes in 3-D Bone Marrow Bioreactors in Vitro  

PubMed Central

Radiation injury to the bone marrow is potentially lethal due to the potent DNA-damaging effects on cells of the hematopoietic system, including bone marrow stem cell, progenitor, and the precursor cell populations. Investigation of radiation genotoxic effects on bone marrow progenitor/precursor cells has been challenged by the lack of optimal in vitro surrogate organ culture systems, and the overall difficulty to sustain lineage-specific proliferation and differentiation of hematopoiesis in vitro. We report the investigation of radiation genotoxic effects in bone marrow cultures of C57Bl/6 mice established in 3-D bioreactors, which sustain long-term bone marrow cultures. For these studies, genotoxicity is measured by the induction of micronucleated reticulocytes (MN-RET). The kinetics and dose-response relationship of MN-RET induction in response to gamma-radiation of bioreactor-maintained bone marrow cultures are presented. Our data showed that 3-D long-term bone marrow cultures had sustained erythropoiesis capable of generating reticulocytes up to 8 weeks. The peak time-interval of viable cell output and percentage of reticulocytes increased steadily and reached the initial peak between the 14th to 21st days after inoculations. This was followed by a rebound or staying relatively constant until week 8. The percentage of MN-RET reached the maximum between 24 and 32 hours post 1 Gy gamma-ray. There was a near linear MN-RET induction by gamma radiation from 0 Gy to 1.0 Gy, followed by an attenuated increase to 1.5 – 2.0 Gy. The MN-RET response showed a downtrend beyond 2 Gy. Our data suggest that bone marrow culture in the 3-D bioreactor may be a useful organ culture system for the investigation of radiation genotoxic effect in vitro.

Sun, Hongliang; Dertinger, Stephen D.; Hyrien, Ollivier; David Wu, J. H.; Chen, Yuhchyau

2009-01-01

121

Decay Curves and Half-lives of Gamma-Emitting States from a Study of Prompt Fission Gamma Radiation  

Microsoft Academic Search

Measurements were made on the time distributions of the prompt gamma radiation emitted from fragments in the thermal-neutron induced fission of 235U. The gamma radiation emitted during different time intervals after the fission event was studied with the help of a collimator, the position of which was changed along the path of the fragments. In this way decay curves were

H. Albinsson

1971-01-01

122

Effect of gamma radiation on membrane fluidity of MOLT-4 nuclei  

SciTech Connect

These experiments measured the effect of gamma radiation on the nuclear envelope using doxyl-fatty acid spin-label probes. Nuclei were isolated from cultured MOLT-4 cells, a radiation-sensitive human T-cell lymphocyte. Membrane fluidity was measured from the electron paramagnetic resonance spectra of the probes. MOLT-4 cells were grown under standard conditions, and suspensions were exposed to 60Co gamma radiation at room temperature. The spectra of 5-doxylstearic acid in the nuclei were those of a strongly immobilized label. A difference in the membrane fluidity was detected in a series of experiments comparing labeled irradiated and nonirradiated nuclei. The change in fluidity was measured by comparing the changes in the order parameter, S, of the spin label in irradiated nuclei with those in control nuclei. The change in the S ratio is dependent on radiation dose, increasing with doses up to 15 Gy. The maximum change of the order parameter with time after irradiation occurs 16-20 h after radiation exposure. These observations are correlated with changes in cell viabilities.

McClain, D.E.; Trypus, C.A.; May, L. (Armed Forces Radiobiology Research Institute, Bethesda, MD (USA))

1990-09-01

123

Anomalous primary radiation from the Leksell Gamma Knife Unit  

SciTech Connect

The Leksell Gamma Knife Unit, Type U, utilizes 201 separate {sup 60}Co sources intersecting at a common focus for radiosurgical treatment of the brain. It has been generally understood that all primary unattenuated radiation beams are confined with the protective housing during all phases of Gamma Knife operations. The authors have found that when the unit`s shielding door is lowered for treatment, twelve primary beams exit the unit`s door opening. Furthermore, in the original Gamma Knife unit design, two of the twelve primary beams failed to be attenuated by either the unit base or the unit wings. This has implications for the design of structural shielding and the protection of personnel during emergency procedures. Engineering modifications to eliminate the problem are discussed. 1 ref., 2 figs.

Shearer, D.R. [Rhode Island Hospital, Providence, RI (United States); Roventine, W.A. [Radiation Physics Services, Harrisville, RI (United States); Coy, S.R. [Neural Science Center, Coral Gables, FL (United States)

1994-12-01

124

Gamma heating measurements in a mixed radiation field  

SciTech Connect

Gamma hearing measurements have been made in a low-Z assembly irradiated with 14-MeV neutrons and (n,n{prime}) gammas produced by a Texas Nuclear Model 9400 neutron generator. The assembly is composed of 144 magnesium sleeves (5cm {times} 5cm {times} 60cm {times} 3 mm thick) filled with graphite to simulate a fusion blanket test module. Heating measurements were made in the mid-line of the assembly using a proportional counter operating in the Continuously-varied Bias-voltage Acquisition (CBA) mode. The neutron induced atomic recoil signal was rejected by observing the signal rise-time differences inherent to radiations of different LET. The experiment was modelled using the one-dimensional radiation transport code ANISN/PC. The operating limits of this technique were identified by comparing measurements made at different positions in the assembly and then comparing these measurements to the calculated flux. 7 refs., 5 figs., 1 tab.

Chiu, H.K. (Illinois Univ., Urbana, IL (USA). Dept. of Nuclear Engineering); Bennett, E.F.; Micklich, B.J. (Argonne National Lab., IL (USA))

1990-09-01

125

The Gamma-ray galactic diffuse radiation and Cerenkov telescopes  

SciTech Connect

By using the PYTHIA version of the Lund Monte Carlo program, we study the photon yield of proton-proton collisions in the energy range between 10 GeV and 1 TeV. The resulting photon spectrum turns out to scale roughly with incident energy. Then, by folding the energy spectrum of cosmic-ray protons with the distribution of HI and CO, the Galactic diffuse emission of {gamma}-rays above 100 GeV is mapped. Prospects for observing that diffuse radiation with atmospheric Cerenkov telescopes are discussed. Present instruments are able to detect the {gamma}-ray glow of the Galactic center. The latter will be mapped by the next generation of telescopes if their energy threshold is decreased. However, a detailed survey of the Galactic ridge will be a real challenge, even in the long term. The MILAGRO project seems more appropriate. Finally, we investigate the {gamma}-ray emission from weakly interacting massive particles clustering at the Galactic center. It has been speculated that those species are a major component of the halo dark matter. We show that their {gamma}-ray signal is swamped in the Galactic diffuse radiation and cannot be observed at TeV energies. {copyright} {ital 1995 The American Astronomical Society.}

Chardonnet, P. [Theoretical Physics Group ENSLAPP, BP110, F-74941 Annecy-le-Vieux Cedex (France)]|[Universite de Savoie, BP1104, 73011 Chambery Cedex (France); Salati, P. [Theoretical Physics Group ENSLAPP, BP110, F-74941 Annecy-le-Vieux Cedex (France)]|[Universite de Savoie, BP1104, 73011 Chambery Cedex (France)]|[Institut Universitaire de France; Silk, J. [545 Campbell Hall, Astronomy Department, University of California at Berkeley, Berkeley, California 94720 (United States); Grenier, I. [Departement dAstrophysique, Centre dEtudes Nucleaires de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Smoot, G. [Building 50, Room 205, Lawrence Berkeley Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

1995-12-01

126

Modeling the radiation doses from terrestrial gamma-ray flashes  

NASA Astrophysics Data System (ADS)

Terrestrial gamma-ray flashes (TGFs) are intense bursts of gamma-rays that originate from thunderclouds, from altitudes that commercial aircraft fly. Based upon the fluence of gamma-rays measured by the RHESSI spacecraft, Dwyer et al. [2010] inferred radiation doses to individuals inside aircraft in the 0.001 - 0.1 Sv range, depending upon the assumed size of the TGF source region. The largest doses occur when an aircraft is directly struck by the energetic electron beam that produces the TGF. The relativistic feedback discharge model is a self-consistent model that includes the generation of runaway electrons via the positron and x-ray feedback mechanisms and the electric field changes due to the resulting ionization and low-energy electron and ion currents. This model has successfully explained many properties of TGFs, including the gamma-ray intensities, durations, multi-pulsed structures as well as discharge currents and radio emissions. In this presentation we discuss new radiation dose calculations based upon the relativistic feedback discharge model and compare these calculations to previous work.

Dwyer, Joseph; Liu, Ningyu; Rassoul, Hamid

2013-04-01

127

Production of light photinos in radiative decays of the form (. pi. /sup 0/. -->. gamma-tildegamma-tilde. gamma. )  

SciTech Connect

The probability of creation of light photinos in the radiative decay of the neutral pion, (..pi../sup 0/..-->..gamma-tildegamma-tilde..gamma..), is determined. Experimental limits on the mass and mass splitting of scalar quarks are used to determine the upper limit for the branching ratio in this process. The result is BR(..pi../sup 0/..-->..gamma-tildegamma-tilde..gamma..)approx. <10/sup -16/.

Dobrolyubov, M.I.; Ignat'ev, A.Y.

1988-06-01

128

Corrosion of copper-based materials in gamma radiation  

Microsoft Academic Search

The corrosion behaviors of pure copper (CDA 101), 7% aluminum-copper bronze (CDA 613) and 30% nickel-copper (CDA 715) are being studied in a gamma radiation field of 1 x 10⁵ R\\/h. These studies are in support of the Nevada Nuclear Waste Storage Investigations (NNWSI) Project, by Lawrence Livermore National Laboratory (LLNL), of copper-based materials for possible use in container systems

Yunker

1986-01-01

129

Observations of gamma radiation from the galactic center region  

Microsoft Academic Search

High resolution measurements of gamma-radiation, greater than 15 MeV, emitted from the galactic center were made during balloon flights in 1971 and 1975. The prominent feature observed in 1971 is a 29 deg wide enhancement lying along and just below the galactic equator. It is primarily confined and has an energy spectrum which appears to be dominated by pi deg-decay

G. H. Share; R. L. Kinzer; J. Samimi; A. Jabbari-Azad

1977-01-01

130

Influence of gamma radiation onto polymeric matrix with papain  

NASA Astrophysics Data System (ADS)

Papain is a proteolytic enzyme that has been widely used as debridement agent for scars and wound healing treatment. However, papain presents low stability, which limits its use to extemporaneous or short shelf-life formulations. The purpose of this study was to entrap papain into a polymeric matrix in order to obtain a drug delivery system that could be used as medical device. Since these systems must be sterile, gamma radiation is an interesting option and presents advantages in relation to conventional agents: no radioactive residues are formed; the product can be sterilized inside the final packaging and has an excellent reliability. The normative reference for the establishment of the sterilizing dose determines 25 kGy as the inactivation dose for viable microorganisms. A silicone dispersion was selected to prepare membranes containing 2% (w/w) papain. Irradiated and non-irradiated membranes were simultaneously assessed in order to verify whether gamma radiation interferes with the drug-releasing profile. Results showed that irradiation does not affect significantly papain release and its activity. Therefore papain shows radioresistance in the irradiation conditions applied. In conclusion, gamma radiation can be easily used as sterilizing agent without affecting the papain release profile and its activity onto the biocompatible device is studied.

Zulli, Gislaine; Lopes, Patrícia Santos; Velasco, Maria Valéria Robles; Alcântara, Mara Tânia Silva; Rogero, Sizue Ota; Lugao, Ademar Benévolo; Mathor, Monica Beatriz

2010-03-01

131

Naturally induced secondary radiation in interplanetary space: Preliminary analyses for gamma radiation and radioisotope production from thermal neutron activation  

Microsoft Academic Search

Thermal neutron activation analyses were carried out for various space systems components to determine gamma radiation dose rates and food radiation contamination levels. The space systems components selected were those for which previous radiation studies existed. These include manned space vehicle radiation shielding, liquid hydrogen propellant tanks for a Mars mission, and a food supply used as space vehicle radiation

Heriberto Plaza-Rosado

1991-01-01

132

Radiation metabolomics. 1. Identification of minimally invasive urine biomarkers for gamma-radiation exposure in mice.  

PubMed

Gamma-radiation exposure has both short- and long-term adverse health effects. The threat of modern terrorism places human populations at risk for radiological exposures, yet current medical countermeasures to radiation exposure are limited. Here we describe metabolomics for gamma-radiation biodosimetry in a mouse model. Mice were gamma-irradiated at doses of 0, 3 and 8 Gy (2.57 Gy/min), and urine samples collected over the first 24 h after exposure were analyzed by ultra-performance liquid chromatography-time-of-flight mass spectrometry (UPLC-TOFMS). Multivariate data were analyzed by orthogonal partial least squares (OPLS). Both 3- and 8-Gy exposures yielded distinct urine metabolomic phenotypes. The top 22 ions for 3 and 8 Gy were analyzed further, including tandem mass spectrometric comparison with authentic standards, revealing that N-hexanoylglycine and beta-thymidine are urinary biomarkers of exposure to 3 and 8 Gy, 3-hydroxy-2-methylbenzoic acid 3-O-sulfate is elevated in urine of mice exposed to 3 but not 8 Gy, and taurine is elevated after 8 but not 3 Gy. Gene Expression Dynamics Inspector (GEDI) self-organizing maps showed clear dose-response relationships for subsets of the urine metabolome. This approach is useful for identifying mice exposed to gamma radiation and for developing metabolomic strategies for noninvasive radiation biodosimetry in humans. PMID:18582157

Tyburski, John B; Patterson, Andrew D; Krausz, Kristopher W; Slavík, Josef; Fornace, Albert J; Gonzalez, Frank J; Idle, Jeffrey R

2008-07-01

133

Effect of gamma radiation on membrane fluidity of MOLT-4 nuclei  

SciTech Connect

These experiments measured the effect of gamma radiation on the nuclear envelope using doxyl-fatty acid spin-label probes. Nuclei were isolated from cultured MOLT-4 cells, a radiation-sensitive human T-cell lymphocyte. Membrane fluidity was measured from the electron paramagnetic resonance spectra of the probes. MOLT-4 cells were grown under standard conditions, and suspension were exposed to CO radiation at room temperature. The spectra of 5-doxylstearic acid in the nuclei were those of a strongly immobilized label. A difference in the membrane fluidity was detected in a series of experiments comparing labeled irradiated and nonirradiated nuclei. The change in fluidity was measured by comparing the changes in the order parameter, S, of the spin label in irradiated nuclei with those in control nuclei.

McClain, D.E.; Trypus, C.A.; May, L.

1990-01-01

134

Protracted low-dose radiation priming and response of liver to acute gamma and proton radiation.  

PubMed

Abstract This study evaluated liver from C57BL/6 mice irradiated with low-dose/low-dose-rate (LDR) ?-rays (0.01 Gy, 0.03 cGy/h), with and without subsequent exposure to acute 2 Gy gamma or proton radiation. Analyses were performed on day 56 post-exposure. Expression patterns of apoptosis-related genes were strikingly different among irradiated groups compared with 0 Gy (p < 0.05). Two genes were affected in the Gamma group, whereas 10 were modified in the LDR + Gamma group. In Proton and LDR + Proton groups, there were six and 12 affected genes, respectively. Expression of genes in the Gamma (Traf3) and Proton (Bak1, Birc2, Birc3, Mcl1) groups was no longer different from 0 Gy control group when mice were pre-exposed to LDR ?-rays. When each combined regimen was compared with the corresponding group that received acute radiation alone, two genes in the LDR + Gamma group and 17 genes in the LDR + Proton group were modified; greatest effect was on Birc2 and Nol3 (> 5-fold up-regulated by LDR + Protons). Oxygen radical production in livers from the LDR + Proton group was higher in LDR, Gamma, and LDR + Gamma groups (p < 0.05 vs. 0 Gy), but there were no differences in phagocytosis of E. coli. Sections stained with hematoxylin and eosin (H&E) suggested more inflammation, with and without necrosis, in some irradiated groups. The data demonstrate that response to acute radiation is dependent on radiation quality and regimen and that some LDR ?-ray-induced modifications in liver response were still evident nearly 2 months after exposure. PMID:23869974

Gridley, D S; Mao, X W; Cao, J D; Bayeta, E J M; Pecaut, M J

2013-08-14

135

S179D prolactin diminishes the effects of UV light on epidermal gamma delta T cells  

Microsoft Academic Search

Epidermal gamma delta T cells (??T) and Langerhans cells (LC) are immune cells altered by exposure to ultraviolet radiation (UVB), a powerful stressor resulting in immune suppression. Prolactin (PRL) has been characterized as an immunomodulator, particularly during stress. In this study, we have asked whether separate administration of the 2 major forms of prolactin, unmodified and phosphorylated, to groups of

Esther A. Guzmán; John L. Langowski; Ariel De Guzman; H. Konrad Muller; Ameae M. Walker; Laurie B. Owen

2008-01-01

136

Current Trends in Gamma Radiation Detection for Radiological Emergency Response  

SciTech Connect

Passive and active detection of gamma rays from shielded radioactive materials, including special nuclear materials, is an important task for any radiological emergency response organization. This article reports on the current trends and status of gamma radiation detection objectives and measurement techniques as applied to nonproliferation and radiological emergencies. In recent years, since the establishment of the Domestic Nuclear Detection Office by the Department of Homeland Security, a tremendous amount of progress has been made in detection materials (scintillators, semiconductors), imaging techniques (Compton imaging, use of active masking and hybrid imaging), data acquisition systems with digital signal processing, field programmable gate arrays and embedded isotopic analysis software (viz. gamma detector response and analysis software [GADRAS]1), fast template matching, and data fusion (merging radiological data with geo-referenced maps, digital imagery to provide better situational awareness). In this stride to progress, a significant amount of interdisciplinary research and development has taken place–techniques and spin-offs from medical science (such as x-ray radiography and tomography), materials engineering (systematic planned studies on scintillators to optimize several qualities of a good scintillator, nanoparticle applications, quantum dots, and photonic crystals, just to name a few). No trend analysis of radiation detection systems would be complete without mentioning the unprecedented strategic position taken by the National Nuclear Security Administration (NNSA) to deter, detect, and interdict illicit trafficking in nuclear and other radioactive materials across international borders and through the global maritime transportation–the so-called second line of defense.

Mukhopadhyay, S., Guss, P., Maurer, R.

2011-09-01

137

Super-Eddington radiation transfer in soft gamma repeaters  

NASA Astrophysics Data System (ADS)

Bursts from soft gamma repeaters (SGRs) have been shown to be super-Eddington by a factor of 1000 and have been persuasively associated with compact objects. Super-Eddington radiation transfer on the surface of a strongly magnetic (greater than or equal to 1013 G) neutron star is studied and related to the observational constraints on SGRs. In strong magnetic fields, Thompson scattering is suppressed in one polarization state, so super-Eddington fluxes can be radiated while the plasma remains in hydrostatic equilibrium. We discuss a model which offers a somewhat natural explanation for the observation that the energy spectra of bursts with varying intensity are similar. The radiation produced is found to be linearly polarized to one part in 1000 in a direction determined by the local magnetic field, and intensity variations between bursts are understood as a change in the radiating area on the source. The net polarization is inversely correlated with burst intensity. Further, it is shown that for radiation transfer calculations in limit of superstrong magnetic fields, it is sufficient to solve the radiation transfer for the low opacity state rather than the coupled equations for both. With this approximation, standard stellar atmosphere techniques are utilized to calculate the model energy spectrum.

Ulmer, Andrew

1994-12-01

138

Radiation Field in Air Due to Distributed Gamma-Ray Sources in the Ground.  

National Technical Information Service (NTIS)

A much more complete and detailed picture of the external environmental gamma-ray radiation field has been obtained through gamma-ray transport calculations of exposure rates, differential energy spectra, integral exposure rate spectra, and angular exposu...

H. Beck G. de Planque

1968-01-01

139

EFFECTS OF GAMMA RADIATION ON ELECTROCHEMICAL PROPERTIES OF IONIC LIQUIDS  

SciTech Connect

The electrochemical properties of ionic liquids (ILs) make them attractive for possible replacement of inorganic salts in high temperature molten salt electrochemical processing of nuclear fuel. To be a feasible replacement solvent, ILs need to be stable in moderate and high doses of radiation without adverse chemical and physical effects. Here, we exposed seven different ILs to a 1.2 MGy dose of gamma radiation to investigate their physical and chemical properties as they related to radiological stability. The azolium-based ILs experienced the greatest change in appearance, but these ILs were chemically more stable to gamma radiation than some of the other classes of ILs tested, due to the presence of aromatic electrons in the azolium ring. All the ILs exhibited a decrease in their conductivity and electrochemical window (at least 1.1 V), both of which could affect the utility of ILs in electrochemical processing. The concentration of the irradiation decomposition products was less than 3 mole %, with no impurities detectable using NMR techniques.

Visser, A; Nicholas Bridges, N; Thad Adams, T; John Mickalonis, J; Mark02 Williamson, M

2009-04-21

140

Gamma\\/delta cells in tissue from patients with sarcoidosis  

Microsoft Academic Search

BACKGROUND: Because gamma\\/delta T lymphocytes (gamma delta cells) respond to myco-bacterial antigens in vitro and accumulate in the skin lesions of patients with certain granulomatous infections (leprosy, leishmaniasis), it was hypothesised that these cells might have a role in the pathogenesis of sarcoidosis, a disease also characterised by granuloma formation. Having failed to demonstrate an increase in gamma delta cells

M L Wilsher; M Hallowes; N M Birchall

1996-01-01

141

Natural Radiation from Soil using Gamma-Ray Spectrometry  

SciTech Connect

We have studied the distribution of natural radioactivity in the soil of Interlagos, in Sao Paulo city and Billings Reservoir, in Sao Bernardo do Campo, Sao Paulo, Brazil. The main contribution of the effective radiation dose is due to the elements of the {sup 238}Th decay series, with smaller contributions from {sup 40}K and the elements of the series of {sup 238}U. The results indicate the dose in all of the studied areas is around the average international dose due to external exposure to gamma rays (0.48 mSv/yr) proceeding from natural terrestrial elements.

Silveira, M. A. G.; Moreira, R. H.; Paula, A. L. C. de [Centro Universitario da FEI, Sao Bernardo do Campo, Sao Paulo (Brazil); Medina, N. H. [Instituto de Fisica da Universidade de Sao Paulo, Sao Paulo (Brazil)

2009-06-03

142

Heavy ion radiative capture: 12C(12C,{gamma})  

SciTech Connect

The heavy ion radiative capture reaction 12C(12C,{gamma}) has been investigated around a beam energy of 16 MeV. The total cross-section has been measured with the Fragment Mass Analyser at Argonne National Laboratory and found to be somewhat larger than has previously been measured. A subsequent measurement with the Gammasphere array has shown that a considerable proportion of this extra cross-section relates to a highly non-statistical decay through high-lying states in 24Mg.

Jenkins, D.G.; Fulton, B.R.; Pearson, J. [Department of Physics, University of York, York, YO10 5DD (United Kingdom); Lister, C.J.; Carpenter, M.P.; Freeman, S.; Hammond, N.; Janssens, R.V.F.; Khoo, T.L.; Lauritsen, T.; Moore, E.F.; Wuosmaa, A.H. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Fallon, P.; Goergen, A.; Macchiavelli, A.O.; McMahan, M. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720 (United States); Freer, M. [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom); Haas, F. [IReS, Centre National de la Recherche Scientifique, F-67037 Strasbourg Cedex 2 (France)

2004-02-27

143

Population doses from environmental gamma radiation in Iraq  

Microsoft Academic Search

The exposure rates due to external gamma radiation were measured in 11 Iraqi governerates. Measurements were performed with an Environmental Monitoring System (RSS-111) in open air 1 m above the ground. The average absorbed dose rate in each governerate was as follows (number x 10(-2) microGy h-1): Babylon (6.0), Kerbala (5.3), Al-Najaf (5.4), Al-Kadysia (6.5), Wasit (6.5), Diala (6.5), Al-Anbar

B. A. Marouf; A. S. Mohamad; J. S. Taha; I. K. al-Haddad

1992-01-01

144

Geraniin down regulates gamma radiation-induced apoptosis by suppressing DNA damage.  

PubMed

Gamma ray irradiation triggers DNA damage and apoptosis of proliferating stem cells and peripheral immune cells, resulting in the destruction of intestinal crypts and lymphoid system. Geraniin is a natural compound extracts from an aquatic plant Nymphaea tetragona and possesses good antioxidant property. In this study, we demonstrate that geraniin rescues radiosensitive splenocytes and jejunal crypt cells from radiation-induced DNA damage and apoptosis. Isolated splenocytes from C57BL/6 mice treated with geraniin were protected against radiation injury of 2 Gy irradiation through the enhancement of the proliferation and attenuation of DNA damage. Also, geraniin inhibited apoptosis in radiosensitive splenocytes by reducing the expression level and immunoreactivity of proapoptotic p53 and Bax and increasing those of anti-apoptotic Bcl-2. In mice exposed to radiation, geraniin treatment protected splenocytes and intestinal crypt cells from radiation-induced cell death. Our results suggest that geraniin presents radioprotective effects by regulating DNA damage on splenocytes, exerting immunostimulatory capacities and inhibiting apoptosis of radiosensitive immune cells and jejunal crypt cells. Therefore, geraniin can be a radioprotective agent against ?-irradiation exposure. PMID:23541438

Bing, So Jin; Ha, Danbee; Kim, Min Ju; Park, Eunjin; Ahn, Ginnae; Kim, Dae Seung; Ko, Ryeo Kyeong; Park, Jae Woo; Lee, Nam Ho; Jee, Youngheun

2013-03-26

145

Modification of radiation lesion to Chinese hamster fibroblast chromosomes in cell cultures. Report 1. Caffeine used to investigate the effect of repair on yield of aberrations at different stages of the cell cycle. [. gamma. rays  

Microsoft Academic Search

A study was made of the effect of caffeine and sodium benzoate (0.8 to 8.0 mM) on the yield of chromosomal aberrations in cells of Chinese hamsters exposed to radiation at the Gâ and S stages. For proper determination of the modification effect, consideration was given to the slower advance through the cell cycle induced by caffeine, as well as

K. M. Saugabaeva; L. Kh. Eidus; E. E. Ganassi

1979-01-01

146

Structurally divergent human T cell receptor. gamma. proteins encoded by distinct C. gamma. genes  

SciTech Connect

The human T cell receptor (TCR) ..gamma.. polypeptide occurs in structurally distinct forms on certain peripheral blood T lymphocytes. Complementary DNA clones representing the transcripts of functionally rearranged TCR ..gamma.. genes in these cells have been analyzed. The expression of a disulfide-linked and a nondisulfide-linked form of TCR ..gamma.. correlates with the use of the C..gamma..1 and C..gamma..2 constant-region gene segments, respectively. Variability in TCR ..gamma.. polypeptide and disulfide linkage is determined by the number of copies and the sequence of a repeated segment of the constant region. Thus, C..gamma..1 and C..gamma..2 are used to generate structurally distinct, yet functional, T3-associated receptor complexes on peripheral blood lymphocytes. Tryptic peptide mapping suggests that the T3-associated TCR ..gamma.. and delta peptides in the nondisulfide-linked form are distinct.

Krangel, M.S.; Band, H.; Hata, S.; McLean, J.; Brenner, M.B.

1987-07-03

147

Radiation effects in solar cells  

NASA Astrophysics Data System (ADS)

Two types of space solar cells, silicon single-junction and InGaP/GaAs/Ge triple-junction (3J) solar cells, have been primarily adopted for spacecraft. The conversion efficiencies of the solar cells under AM0, 1 sun condition are ~17% for silicon and ~30% for 3J cells. Radiation degradation occurs in space due to high-energy electrons and protons existing in space environment. The degradation is caused by radiation induced crystal defects which act as minority-carrier recombination centers and majority-carrier trap centers. The 3J cells are superior radiation resistant to the silicon cells, and this is mainly because the InGaP top-subcell has property of very high radiation resistance.

Imaizumi, Mitsuru; Ohshima, Takeshi

2013-05-01

148

Decontamination of black pepper and red pepper by gamma radiation  

NASA Astrophysics Data System (ADS)

The present study was conducted in order to evaluate the efficacy of gamma radiation to decontaminate imported black pepper and red pepper, which are commonly consumed in Algeria. Initial microbial load of the order of 107-108 microorganisms per gram of spices were found. It was established that a radiation dose of 6 kGy is sufficient to reduce the microbial contamination to below a level of 103 microorganisms per gram for both spices. Integrating irradiation with polyethylene packaging material afforded good protection against recontamination during 4 months of storage. The biological properties including sugars and essential oils were not affected by the irradiation treatment. Furthermore, at the dose of 8 kGy no sensory changes of spices were detected.

Oularbi, S.; Mansouri, B.

1996-09-01

149

An investigation of gamma background radiation in Hamadan province, Iran.  

PubMed

The general population, everywhere in the world is exposed to a small dose of ionising radiation from natural sources. Stochastic effects such as cancer and genetic disorders are caused when living creatures are exposed to low doses. In Iran, it is measured in some cities, especially in high-background areas such as Ramsar, but so far there is no measurement in the Hamadan province. Hamadan is located in the west of Iran. Measurements were performed using a RDS-110 survey meter, CaSO(4):Dy thermoluminecense dosimetries (TLDs) and a Harshaw 4000 TLD reader. To estimate the dose rate  outdoors, four stations along the main directions (north, south, west and east) and one in the town centre were selected. Mean annual X and gamma equivalent dose in Hamadan province are 1.12±0.22  and 1.66±0.07 mSv, which related to RDS-110 survey meter and TLDs measurements, respectively. The TLDs and RDS-110 results are representative of the external photon radiation doses for the selected monitoring locations and for those locations for the hours during which the measurements were taken, respectively. Maximum and minimum of external photon radiation doses are related to Hamadan and Kaboudar-Ahang towns, respectively. According to the results of the study, it seems that the annual X and gamma equivalent dose in Hamadan province exceeded the global mean external exposure amounts by the UNSCEAR, and further studies are needed to measure internal exposures to determine the total environmental radiation level in  Hamadan province. PMID:22570508

Rostampour, Nima; Almasi, Tinoosh; Rostampour, Masoumeh; Mohammadi, Mohammad; Ghazikhanlou Sani, Karim; Khosravi, Hamid R; Pooya, S Mehdi Hosseini; Golzar, Bahman; Jabari Vesal, Naghi

2012-05-07

150

Quercetin ameliorates gamma radiation-induced DNA damage and biochemical changes in human peripheral blood lymphocytes.  

PubMed

We investigated the radioprotective efficacy of quercetin (QN), a naturally occurring flavonoid against gamma radiation-induced damage in human peripheral blood lymphocytes and plasmid DNA. In plasmid study, QN at different concentrations (3, 6, 12, 24 and 48 microM) were pre-incubated with plasmid DNA for 1h followed by exposure of 6 Gy radiation. Among all concentrations of QN used, 24 microM showed optimum radioprotective potential. To establish the most effective protective concentration of QN in lymphocytes, the cells were pre-incubated with 3, 6, 12, 24 and 48 microM of QN for 30 min and then exposed to 4 Gy gamma-radiation. The concentration-dependent effects of QN were evaluated by scoring micronuclei (MN) frequencies. The results showed that QN decreased the MN frequencies dose dependently, but the effect was more pronounced at 24 microM. Thus, 24 microM of QN was selected as the optimum concentration and was further used to evaluate its radioprotective effect in lymphocytes. For that a separate experiment was carried out, in which lymphocytes were incubated with QN (24 microM) for 30 min and exposed to different doses of radiation (1, 2, 3 and 4 Gy). Genetic damage (MN, dicentric aberration and comet attributes) and biochemical changes were measured to evaluate the effect of QN on gamma-radiations (1-4 Gy). Radiation exposed showed significant increases in the genetic damage and thiobarbituric acid reactive substances (TBARS) accompanied by a significant decrease in the antioxidant status. QN pretreatment significantly decreased the genetic damage and TBARS and improved antioxidant status through its antioxidant potential. Altogether, our findings encourage further mechanistic and in vivo studies to investigate radioprotective efficacy of QN. PMID:18436471

Devipriya, Nagarajan; Sudheer, Adluri Ram; Srinivasan, Marimuthu; Menon, Venugopal P

2008-03-15

151

An experimental search for gamma radiation associated with thunderstorm activity  

SciTech Connect

This experiment is a repeat of an earlier experiment, but with more sensitive apparatus and in a location with a higher incidence of thunderstorm activity. The earlier experiment was undertaken by Ashby and Whitehead to investigate the theory that ball lightning might be associated with the annihilation of small amounts of antimatter, and it yielded some very interesting but inconclusive results. In the course of about 12 months of data taking, four high rate bursts of gamma radiation were detected. These events lasted a few seconds and had many thousands of counts (16500, 5000, 3700, and [gt] 7700. Unfortunately, the association of these gamma ray bursts with thunderstorms or ball lightning was not clearly established, although one of the bursts did occur during a local thunderstorm in rough coincidence with a lightning bolt striking a flagpole about 100 yards from the gamma ray detection crystals. A pulse height spectrum taken for this burst (no spectrum was taken for the other three) exhibited a significant peak, well above background, the energy of which appeared to be compatible with the 511 keV positron annihilation line. While the peak could not be unambiguously attributed to positron annihilation, this certainly appeared to be the most likely source.

Fryberger, D.

1992-11-01

152

An experimental search for gamma radiation associated with thunderstorm activity  

SciTech Connect

This experiment is a repeat of an earlier experiment, but with more sensitive apparatus and in a location with a higher incidence of thunderstorm activity. The earlier experiment was undertaken by Ashby and Whitehead to investigate the theory that ball lightning might be associated with the annihilation of small amounts of antimatter, and it yielded some very interesting but inconclusive results. In the course of about 12 months of data taking, four high rate bursts of gamma radiation were detected. These events lasted a few seconds and had many thousands of counts (16500, 5000, 3700, and {gt} 7700. Unfortunately, the association of these gamma ray bursts with thunderstorms or ball lightning was not clearly established, although one of the bursts did occur during a local thunderstorm in rough coincidence with a lightning bolt striking a flagpole about 100 yards from the gamma ray detection crystals. A pulse height spectrum taken for this burst (no spectrum was taken for the other three) exhibited a significant peak, well above background, the energy of which appeared to be compatible with the 511 keV positron annihilation line. While the peak could not be unambiguously attributed to positron annihilation, this certainly appeared to be the most likely source.

Fryberger, D.

1992-11-01

153

Gamma radiation effects on commercial Mexican bread making wheat flour  

NASA Astrophysics Data System (ADS)

Gamma irradiation is considered to be an alternative method for food preservation to prevent food spoilage, insect infestation and capable of reducing the microbial load. In the present investigation, commercial Mexican bread making wheat flour was irradiated at 1.0 kGy using a 60C Gammabeam 651 PT irradiator facility. No changes were detected in moisture, protein and ashes in gamma irradiated samples as compared to those of non-irradiated samples. Slight radiation effects were observed in the alveogram values and farinograph properties; the falling number decreased 11%, the absorption as well as the mixing tolerance were practically unchanged by irradiation. An increase of 15% in the stability value and a 29% in the dough development time were observed. Also the deformation energy decreased 7% with no change at all in the tenacity/extensibility factor. Total aerobic, yeast and mold counts were reduced 96%, 25% and 75%; respectively by the irradiation process. The obtained results confirm that gamma irradiation is effective in reducing the microbial load in bread making wheat flour without a significant change in the physicochemical and baking properties.

Agúndez-Arvizu, Z.; Fernández-Ramírez, M. V.; Arce-Corrales, M. E.; Cruz-Zaragoza, E.; Meléndrez, R.; Chernov, V.; Barboza-Flores, M.

2006-04-01

154

Radiomodifying and anticlastogenic effect of Zingerone on Swiss albino mice exposed to whole body gamma radiation.  

PubMed

The radioprotective effect and antigenotoxic potential of phenolic alkanone, Zingerone (ZO) were investigated in Swiss albino mice exposed to gamma radiation. To study the optimum dose for radiation protection, mice were administered with ZO (10-100mg/kgb.wt.), once daily for five consecutive days. One hour after the last administration of ZO on the fifth day, animals were whole body exposed to 10 Gy gamma radiations. The radioprotective potential was assessed using animal survival at an optimal ZO dose of 20mg/kgb.wt., administered prior to 7-11 Gy. Further, the radioprotective potential of ZO was also analyzed by haemopoietic stem cell survival (CFU) assay, mouse bone marrow micronucleus test and histological observations of intestinal and bone marrow damage. Effect of ZO pretreatment on radiation-induced changes in glutathione (GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT) and lipid peroxidation (LPx) levels was also analyzed. ZO treatment resulted increase in the LD(50/30) by 1.8 Gy (dose reduction factor = 1.2). The number of spleen colonies after whole body irradiation of mice (4.5 or 7.5 Gy) was increased when ZO was administered 1h prior to irradiation. The histological observations indicated a decline in the villus height and crypt number with an increase in goblet and dead cell population in the irradiated group, which was normalized by pretreatment with ZO. A significant (p < 0.001) reduction in micronucleated polychromatic, normochromatic erythrocytes, increased PCE/NCE ratio, increase in the GSH, GST, SOD, CAT and decreased LPx levels were observed in ZO pretreated group when compared to the irradiated animals. Our findings demonstrate the potential of ZO in mitigating radiation-induced mortality and cytogenetic damage, which may be attributed to inhibition radiation-induced decline in the endogenous antioxidant levels and scavenging of radiation-induced free radicals. PMID:19463966

Rao, B Nageshwar; Rao, B S Satish; Aithal, B Kiran; Kumar, M R Sunil

2009-05-20

155

Enhancement of natural background gamma-radiation dose around uranium microparticles in the human body.  

PubMed

Ongoing controversy surrounds the adverse health effects of the use of depleted uranium (DU) munitions. The biological effects of gamma-radiation arise from the direct or indirect interaction between secondary electrons and the DNA of living cells. The probability of the absorption of X-rays and gamma-rays with energies below about 200 keV by particles of high atomic number is proportional to the third to fourth power of the atomic number. In such a case, the more heavily ionizing low-energy recoil electrons are preferentially produced; these cause dose enhancement in the immediate vicinity of the particles. It has been claimed that upon exposure to naturally occurring background gamma-radiation, particles of DU in the human body would produce dose enhancement by a factor of 500-1000, thereby contributing a significant radiation dose in addition to the dose received from the inherent radioactivity of the DU. In this study, we used the Monte Carlo code EGSnrc to accurately estimate the likely maximum dose enhancement arising from the presence of micrometre-sized uranium particles in the body. We found that although the dose enhancement is significant, of the order of 1-10, it is considerably smaller than that suggested previously. PMID:19776147

Pattison, John E; Hugtenburg, Richard P; Green, Stuart

2009-09-23

156

Enhancement of natural background gamma-radiation dose around uranium microparticles in the human body  

PubMed Central

Ongoing controversy surrounds the adverse health effects of the use of depleted uranium (DU) munitions. The biological effects of gamma-radiation arise from the direct or indirect interaction between secondary electrons and the DNA of living cells. The probability of the absorption of X-rays and gamma-rays with energies below about 200 keV by particles of high atomic number is proportional to the third to fourth power of the atomic number. In such a case, the more heavily ionizing low-energy recoil electrons are preferentially produced; these cause dose enhancement in the immediate vicinity of the particles. It has been claimed that upon exposure to naturally occurring background gamma-radiation, particles of DU in the human body would produce dose enhancement by a factor of 500–1000, thereby contributing a significant radiation dose in addition to the dose received from the inherent radioactivity of the DU. In this study, we used the Monte Carlo code EGSnrc to accurately estimate the likely maximum dose enhancement arising from the presence of micrometre-sized uranium particles in the body. We found that although the dose enhancement is significant, of the order of 1–10, it is considerably smaller than that suggested previously.

Pattison, John E.; Hugtenburg, Richard P.; Green, Stuart

2010-01-01

157

Effect of Gamma radiation on microbial population of natural casings  

NASA Astrophysics Data System (ADS)

The high microbial load of fresh and dry natural casings increases the risk of meat product contamination with pathogenic microorganims, agents of foodborn diseases. The aim of this work is to evaluate the killing effect of gamma radiation on the resident microbial population of pork and beef casings, to improve their hygiene and safety. Portions of fresh pork (small intestine and colon) and dry beef casings were irradiated in a Cobalt 60 source with absorbed doses of 1, 2, 5 and 10 kGy. The D10 values of total aerobic microorganisms in the pork casings were 1.65 kGy for colon and 1.54 kGy for small intestine. The D10 value found in beef dry casings (small intestine) was 10.17 kGy. Radurization with 5 kGy was able to reduce, at least, 6 logs the coliform bacteria in pork casings. The killing effect over faecal Streptococci was 4 logs for pork fresh casings and 2 logs for beef dry casings. Gamma radiation with 5 kGy proved to be a convenient method to reduce substantially the microbial population of pork fresh casings. Otherwise, the microbial population of beef dry casings still resisted to 10 kGy.

Trigo, M. J.; Fraqueza, M. J.

1998-06-01

158

Gamma ray driven photovoltaic cells: an interface between nuclear and semiconductor physics  

Microsoft Academic Search

We explore the possibility of utilizing low energy ?-photon radiation from single or multiple radioactive sources, for the production of electron–hole pairs in the semiconductors of photovoltaic cells. Our aim is to produce and store electric energy using this mechanism. The radioactive sources in the GRPVC (gamma ray photovoltaic cell) can be either naturally occurring or manufactured nuclear isomers. The

John K Liakos

2008-01-01

159

Apoptosis after gamma irradiation. Is it an important cell death modality?  

Microsoft Academic Search

Apoptosis and necrosis are two different forms of cell death that can be induced by cytotoxic stress, such as ionizing radiation. We have studied the importance of apoptotic death induced after treatment with 6 Gy of gamma-irradiation in a panel of eight human tumour cell lines of different radiosensitivities. Three different techniques based on the detection of DNA fragmentation have

E Siles; M Villalobos; L Jones; R Guerrero; JJ Eady; MT Valenzuela; MI Núñez; TJ McMillan; JM Ruiz de Almodóvar

1998-01-01

160

Short term effects of gamma radiation on endothelial barrier function: uncoupling of PECAM-1.  

PubMed

A limiting factor in the treatment of cancer with radiotherapy is the damage to surrounding normal tissue, particularly the vasculature. Vessel pathologies are a major feature of the side effects of radiotherapy and little is known about early events that could initiate subsequent diseases. We tested the hypothesis that gamma radiation has early damaging effects on the human endothelial barrier. Two models were used; Human Brain Microcapillary Endothelial Cells (HBMEC), and Human Umbilical Vein Endothelial Cells (HUVEC). Endpoints included Trans-Endothelial Electrical Resistance (TEER), barrier permeability to 10 kDa and 70 kDa tracer molecules, and the localization of F-actin, and junction proteins and the Platelet Endothelial Cell Adhesion Molecule (PECAM-1). Radiation induced a rapid and transient decrease in TEER at 3 h, with effects also seen at the radiotherapy doses. This dip in resistance correlated to the transient loss of PECAM-1 in discrete areas where cells often detached from the monolayer leaving gaps. Redistribution of PECAM-1 was also seen in 3-D human tissue models. By 6 h, the remaining cells had migrated to reseal the barrier, coincident with TEER returning to control levels. Resealed monolayers contained fewer cells per unit area and their barrier function was weakened as evidenced by an increased permeability over 24 h. This is the first demonstration of a transient and rapid effect of gamma radiation on human endothelial barriers that involves cell detachment and the loss of PECAM-1. Considering the association of cell adhesion molecules with vasculopathies, such an effect has the potential to be clinically relevant to the longer-term effects of radiotherapy. PMID:23220351

Sharma, Preety; Templin, Thomas; Grabham, Peter

2012-12-05

161

Gamma Radiation and Virus Multiplication: Factors That Affect the Establishment and Maintenance of L-Cells Chronically Infected with Sindbis Virus.  

National Technical Information Service (NTIS)

Sindbis virus-chronically infected L-cells were established in 14 day-old monolayers by changing the medium every two hours after virus inoculation, and in 24 hour monolayers by changing the medium every 2 or 3 days. Fourteen day-old L-cell monolayers wer...

N. M. Davila

1976-01-01

162

Closed-Form E1 Radiative Strength Functions for Gamma-Decay and Photoabsorption  

SciTech Connect

Photoabsorption cross sections and {gamma}-decay strength functions are calculated and compared with experimental data to test simple phenomenological models of E1 gamma-strength description in the middle-weight and heavy atomic nuclei. Radiative strength functions with energy asymmetric shape are recommended for overall estimation of averaged gamma-strengths. Systematics for giant dipole resonance (GDR) parameters are given.

Plujko, Vladimir A.; Kadenko, Igor M.; Kulich, Elizaveta V.; Gorbachenko, Oleksandr M. [Nuclear Physics Department, Taras Shevchenko National University, Pr. Acad. Glushkova, 2, bldg. 11, 03022 Kyiv (Ukraine)

2009-01-28

163

T-cell receptor gamma delta and gamma transgenic mice suggest a role of a gamma gene silencer in the generation of alpha beta T cells.  

PubMed Central

A T lymphocyte expresses on its surface one of two types of antigen receptor, T-cell receptor alpha beta or T-cell receptor gamma delta, encoded by a pair of somatically rearranged alpha and beta or gamma and delta genes. It has been suggested that alpha beta T cells are generated only from precursor T cells that failed to rearrange gamma and delta genes in a functional form. However, we found that transgenic mice constructed with functionally rearranged gamma and delta genes produce a normal number of alpha beta T cells. The transgene gamma present in these alpha beta T cells is repressed apparently through an associated cis DNA element (silencer). We propose that some T-cell precursors are committed to generate alpha beta T cells independent of the rearrangement status of their gamma gene and that this commitment involves activation of a factor(s) that interacts with the gamma gene-associated silencer. Images

Ishida, I; Verbeek, S; Bonneville, M; Itohara, S; Berns, A; Tonegawa, S

1990-01-01

164

Gamma Radiation Effects on Time-Dependent Iodine Partitioning.  

NASA Astrophysics Data System (ADS)

A need for characterization of the iodine source -term used in safety calculations for hypothesized fission reactor core disruptive accidents has motivated this study in iodine volatility. Previous experimental studies have been directed at evaluating volatility of iodine at a single time shortly (1-12 h) after introduction into the aqueous -phase. This work has explored the very important variables of time in solution and gamma radiation dose rate for a range of iodine concentrations (10('-8) - 10('-5) gI/ml) and pH's (5, 9 and 11). All experiments were performed at (TURN)25(DEGREES)C, first in the absence of a significant radiation field and later with a gamma radiation dose rate ranging from .003 MRad/hr to .06 MRad/hr. Iodine was introduced either as molecular I(,2) or NaI with I-131 (8.04 day half -life) as a tracer. Conditions present during the course of the experiment governed iodine solution chemistry thus determining whether volatile forms (I(,2) and HOI) would predominate. Results of experiments with nonirradiated systems indicated very little volatility with NaI initiated studies. I(,2) initiated systems at pH 5 were the most volatile whereas pH 9 and 11 I(,2) systems showed decreasing volatility with time. This has been explained by analysis of iodine aqueous chemistry. Total iodine concentration dependence has also been addressed. A pronounced radiation-induced reduction in iodine volatility in pH 5 iodide solutions has been demonstrated as well as a dose rate dependence in the transient phase. This effect is more pronounced in higher concentration solutions. As with nonirradiated systems, irradiated alkaline solutions exhibit low volatility. Explanations for the behavior of irradiated systems based on iodine radiolytic chemistry are provided. A computer based model incorporating water radiolysis and iodine radiolytic chemical reactions has been formulated and tested. The model successfully predicts radiation induced volatility changes in pH 5 iodide systems. The experimentally observed dose rate dependence is also verified; however, insufficient knowledge of alkaline system iodine radiolytic interactions prevented success under those conditions.

Marshall, Paul Watson

165

Role of ruvAB genes in UV- and gamma-radiation and chemical mutagenesis in Escherichia coli.  

PubMed

Escherichia coli umuC122::Tn 5 was mutagenized with N-methyl-N'-nitro-N-nitrosoguanidine to isolate mutations that block the residual gamma-radiation mutagenesis observed in umuC strains. Two of these mutations were shown by transductional mapping and plasmid complementation to map in the ruvA and ruvB genes (i.e., ruvA200 and ruvB201). Whereas ruvA200 was complemented by ruvA+ plasmids, the only other known ruvA mutation, ruvA59::Tn10 required both the ruvA+ and ruvB+ genes to show complementation. The ruvA200, ruvB201, ruvA59::Tn10 and ruvB60::Tn10 mutations all reduced gamma-radiation-induced ochre reversion [argE3(Oc)----Arg+] to about 30% of the wild-type level, and they all reduced UV-radiation-induced ochre reversion to about 15% of the wild-type level. The ruvA200 and ruvB201 mutants also showed reduced gamma- and UV-radiation mutagenesis with two other assays [hisG4(Oc)----His+ and Rifs----Rifr]. Streptozotocin mutagenesis (Rifr) was reduced to about half of the wild-type level in ruv strains, but ethyl methanesulfonate mutagenesis was normal. While the umuC strain did not show the oxygen enhancement of gamma-radiation mutagenesis, the ruvA200 strain showed an oxygen effect that was similar to that shown by the wild-type strain. When the ruvA200 mutation was combined with the umuC mutation, gamma-radiation mutagenesis was further reduced to 5% of the wild-type level and cells showed a synergistic sensitization to UV- and gamma-radiation-induced killing. A mutational spectrum analysis indicates a general depression of both umuC-dependent and umuC-independent gamma-radiation mutagenesis in the ruvA strain, which is in contrast with the site-specific reduction in gamma-radiation mutagenesis that is observed in the umuC mutant. The reduced radiation mutagenesis in the ruvA strain could not be correlated with a reduction in transcription of the recA or umuC genes. PMID:2554134

Sargentini, N J; Smith, K C

1989-11-01

166

INVESTIGATIONS OF MOLTEN METALS WITH THE AID OF GAMMA-RADIATIONS  

Microsoft Academic Search

Gamma radiation was employed to investigate some molten metals and ; binary metallic systems. By measuring the number of pulses per minute (n) the ; attenuation (absorbtion) of gamma radiations during passage through a layer of ; molten metal was determined. The following technically pure metals and alloys ; studied were: Mg, Al, Cu, Zn, Sn, Pb, Al-Zn, Al-Cu, Al-Sn,

Belyaev

1961-01-01

167

Neutron and gamma radiation shielding material, structure, and process of making structure  

DOEpatents

The present invention is directed to a novel neutron and gamma radiation shielding material consisting of 95 to 97% by weight SiO/sub 2/ and 5 to 3% by weight sodium silicate. In addition, the method of using this composition to provide a continuous neutron and gamma radiation shielding structure is disclosed.

Hondorp, H.L.

1981-07-06

168

Mechanisms of radiation-induced neoplastic cell transformation  

SciTech Connect

Studies with cultured mammalian cells demonstrated clearly that radiation can transform cells directly and can enhance the cell transformation by oncogenic DNA viruses. In general, high-LET heavy-ion radiation can be more effective than X and gamma rays in inducing neoplastic cell transformation. Various experimental results indicate that radiation-induced DNA damage, most likely double-strand breaks, is important for both the initiation of cell transformation and for the enhancement of viral transformation. Some of the transformation and enhancement lesions can be repaired properly in the cell, and the amount of irrepairable lesions produced by a given dose depends on the quality of radiation. An inhibition of repair processes with chemical agents can increase the transformation frequency of cells exposed to radiation and/or oncogenic viruses, suggesting that repair mechanisms may play an important role in the radiation transformation. The progression of radiation-transformed cells appears to be a long and complicated process that can be modulated by some nonmutagenic chemical agents, e.g., DMSO. Normal cells can inhibit the expression of transforming properties of tumorigenic cells through an as yet unknown mechanism. The progression and expression of transformation may involve some epigenetic changes in the irradiated cells. 38 references, 15 figures, 1 table.

Yang, T.C.H.; Tobias, C.A.

1984-04-01

169

Gamma radiation consequences on desert locust Schistocerca gregaria (Forsk.) digestive system.  

PubMed

Schistocera gregaria (Forsk.) (Orthoptera, Acrididae) remains a major insect pest in Africa, more particularly in the Sahelian zone. Present control methods are only partially efficient. In a previous study, we tested the potentiality of a sterile insect technique (SIT). Males of S. gregaria appeared to be much radiosensitive as already a dose of 3 Gy limited their survival. Gamma-radiations are known to damages the epithelial tissue of midgut, which affects the alimentation in insects. In this work, we show how digestive system of S. gregaria males is affected when submitted to a dose of 4 gamma rays. Nutrition is affected as males stop feeding soon after irradiation and progressively lose weight. Histological analyses on the midgut showed important epithelium damages. The regenerative cells by which the epithelial cells are replaced were damaged on the first days following irradiation. Consequently, regenerative cells are unable to divide and replace the normal loss of midgut cell. After nine days, the entire midgut epithelium was destroyed and only longitudinal muscles layer remained intact. This indicates that low radiation doses should be used if SIT will be applied. PMID:21539264

Dushimirimana, S; Muratori, F; Damiens, D; Hance, T

2010-01-01

170

Search for Charmonium States Decaying to J/\\psi\\gamma \\gamma $ Using Initial-State Radiation Events  

SciTech Connect

We study the processes e{sup +}e{sup -} {yields} (J/{psi}{gamma}{gamma}){gamma} and e{sup +}e{sup -} {yields} (J/{psi}{pi}{sup -}{pi}{sup +}){gamma} where the hard photon radiated from an initial e{sup +}e{sup -} collision with center-of-mass (CM) energy near 10.58 GeV is detected. In the final state J/{psi}{gamma}{gamma} we consider J/{psi}{pi}{sup 0}, J/{psi}{eta}, {chi}{sub c1}{gamma}, and {chi}c{sub 2}{gamma} candidates. The invariant mass of the hadronic final state defines the effective e{sup +}e{sup -} CM energy in each event, so these data can be compared with direct e{sup +}e{sup -} measurements. We report 90% CL upper limits for the integrated cross section times branching fractions of the J/{psi}{gamma}{gamma} channels in the Y (4260) mass region.

Aubert, B.; Barate, R.; Bona, M.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Tisserand, V.; Zghiche, A.; Grauges, E.; /Barcelona U., ECM; Palano, A.; /Bari U. /INFN, Bari; Chen, J.C.; Qi, N.D.; Rong, G.; Wang, P.; Zhu, Y.S.; /Beijing, Inst. High Energy Phys.; Eigen, G.; Ofte, I.; Stugu, B.; /Bergen U.; Abrams, G.S.; /LBL, Berkeley /UC, Berkeley /Birmingham U. /Ruhr U., Bochum /Bristol U. /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UCLA /UC, Riverside /UC, San Diego /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /Ferrara U. /INFN, Ferrara /Frascati /Genoa U. /INFN, Genoa /Harvard U. /Heidelberg U. /Imperial Coll., London /Iowa U. /Iowa State U. /Johns Hopkins U. /Karlsruhe U., EKP /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Louisville U. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT, LNS /McGill U. /Milan U. /INFN, Milan /Mississippi U. /Montreal U. /Mt. Holyoke Coll. /Naples U. /INFN, Naples /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /Padua U. /INFN, Padua /Pennsylvania U. /Perugia U. /INFN, Perugia /Pisa U. /INFN, Pisa /Prairie View A-M /Princeton U. /Rome U. /INFN, Rome /Rostock U. /Rutherford /DAPNIA, Saclay /South Carolina U. /SLAC /Stanford U., Phys. Dept. /SUNY, Stony Brook /Tennessee U. /Texas U. /Texas U., Dallas /Turin U. /INFN, Turin /Trieste U. /INFN, Trieste /Valencia U., IFIC /Victoria U. /Warwick U. /Wisconsin U., Madison /Yale U.

2006-11-30

171

Phoswich scintillator for proton and gamma radiation of high energy  

NASA Astrophysics Data System (ADS)

We present here a Phoswich scintillator design to achieve both high resolution gamma ray detection, and good efficiency for high energy protons. There are recent developments of new high resolution scintillator materials. Especially the LaBr3(Ce) and LaCl3(Ce) crystals have very good energy resolution in the order of 3% for 662 keV gamma radiation. In addition, these materials exhibit a very good light output (63 and 32 photons/keV respectively). A demonstrator detector in the form of an Al cylinder of 24 mm diameter and a total length of 80 mm with 2 mm wall thickness, containing a LaBr3(Ce) crystal of 20 mm diameter and 30 mm length directly coupled to a LaCl3(Ce) crystal of 50 mm length, and closed with a glass window of 5 mm, was delivered by Saint Gobain. To the glass window a Hamamatsu R5380 Photomultiplier tube (PMT) was coupled using silicon optical grease.

Tengblad, O.; Nilsson, T.; Borge, M. J. G.; Briz, J. A.; Carmona-Gallardo, M.; Cruz, C.; Gugliermina, V.; Nácher, E.; Perea, A.; Del Rio, J. Sanchez; Nieves, M. Turrion; Johansson, H. T.; Bergström, J.; Blomberg, E.; Bülling, A.; Gallneby, E.; Hagdahl, J.; Jansson, L.; Jareteg, K.; Masgren, R.; Nordström, M.; Risting, G.; Shojaee, S.; Wittler, H.

2011-11-01

172

Phoswich scintillator for proton and gamma radiation of high energy  

SciTech Connect

We present here a Phoswich scintillator design to achieve both high resolution gamma ray detection, and good efficiency for high energy protons. There are recent developments of new high resolution scintillator materials. Especially the LaBr3(Ce) and LaCl3(Ce) crystals have very good energy resolution in the order of 3% for 662 keV gamma radiation. In addition, these materials exhibit a very good light output (63 and 32 photons/keV respectively).A demonstrator detector in the form of an Al cylinder of 24 mm diameter and a total length of 80 mm with 2 mm wall thickness, containing a LaBr3(Ce) crystal of 20 mm diameter and 30 mm length directly coupled to a LaCl3(Ce) crystal of 50 mm length, and closed with a glass window of 5 mm, was delivered by Saint Gobain. To the glass window a Hamamatsu R5380 Photomultiplier tube (PMT) was coupled using silicon optical grease.

Tengblad, O.; Borge, M. J. G.; Briz, J. A.; Carmona-Gallardo, M.; Cruz, C.; Gugliermina, V.; Nacher, E.; Perea, A.; Sanchez del Rio, J.; Nieves, M. Turrion [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Nilsson, T.; Johansson, H. T.; Bergstroem, J.; Blomberg, E.; Buelling, A.; Gallneby, E.; Hagdahl, J.; Jansson, L.; Jareteg, K.; Masgren, R. [Department of fundamental Physics, Chalmers Univ. of Technology, S-41296 Goeteborg (Sweden); and others

2011-11-30

173

Investigation of discrete {gamma} radiation in interactions of 14.9-MeV neutrons with natural silicon by a total {gamma}-radiation measurement technique  

SciTech Connect

The discrete {gamma} radiation in the interaction of 14.9-MeV neutrons and a natural silicon sample is investigated with a total {gamma}-radiation measurement (TGRM) technique. Fifty prompt {gamma} lines, one delayed {gamma} line, and seven final nuclei are identified. Forty-one possible transitions are designated. Differential production cross sections of 40 {gamma} lines at 40 deg., 55 deg., 90 deg., 125 deg., and 140 deg. are determined. Using relative differential production cross sections, accurate integral isotopic cross sections of the {sup 28}Si(n,p){sup 28}Al reaction are determined, and partial integral isotopic cross sections of the {sup 28}Si(n,n'){sup 28}Si, {sup 28}Si(n,{alpha}){sup 25}Mg, {sup 29}Si(n,n'){sup 29}Si, and {sup 30}Si(n,n'){sup 30}Si reaction channels are also estimated. The present results are in good agreement with some recent experimental and evaluated results.

Zhou Hongyu; Su Jun; Zhao Baokui; Dong Liming; Fan Guoying; Zhang Fengshou [Key Laboratory of Beam Technology and Material Modification of Ministry of Education, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing 100875 (China); Deng Fuguo [Department of Physics, Beijing Normal University, Beijing 100875 (China); Zhao Qiang [School of Nuclear Science and Engineering, North China Electric Power University, Beijing 102206 (China)

2010-10-15

174

Radiation sterilization of fluoroquinolones in solid state: investigation of effect of gamma radiation and electron beam.  

PubMed

The effect of gamma radiation from (60)Co source and 2MeV electron beam was studied on two fluoroquinolone antibiotics viz norfloxacin and gatifloxacin in the solid state. The changes in reflectance spectrum, yellowness index, vibrational characteristics, thermal behavior, UV spectrum, chemical potency (HPLC) and microbiological potency were investigated. ESR measurement gave the number of free radical species formed and their population. The nature of final radiolytic impurities was assessed by studying the HPLC impurity profile. Both norfloxacin and gatifloxacin were observed to be radiation resistant, and did not show significant changes in their physico-chemical properties. They could be radiation sterilized at a dose of 25kGy. PMID:20444612

Singh, Babita K; Parwate, Dilip V; Dassarma, Indrani B; Shukla, Sudhir K

2010-04-20

175

International comparisons of air kerma standards in 137Cs gamma radiation  

Microsoft Academic Search

Comparisons of the air kerma standards of six national laboratories, carried out in 137Cs gamma radiation, show an overall agreement of 0,8 % between the standards. This result is not quite as good as that of comparisons in 60Co gamma radiation, mainly because the evaluation of the ionization-chamber wall correction is less accurate for 137Cs radiation. However, this agreement is

A. Leitner; J. Witzani; M. Boutillon; P. Allisy-Roberts; F. Delaunay; E. Leroy; P. Lamperti; C. Strachotinsky; I. Csete

1997-01-01

176

Mediate gamma radiation effects on some packaged food items  

NASA Astrophysics Data System (ADS)

For most of prepackaged foods a 10 kGy radiation dose is considered the maximum dose needed; however, the commercially available and practically accepted packaging materials must be suitable for such application. This work describes the application of ionizing radiation on several packaged food items, using 5 dehydrated food items, 5 ready-to-eat meals and 5 ready-to-eat food items irradiated in a 60Co gamma source with a 3 kGy dose. The quality evaluation of the irradiated samples was performed 2 and 8 months after irradiation. Microbiological analysis (bacteria, fungus and yeast load) was performed. The sensory characteristics were established for appearance, aroma, texture and flavor attributes were also established. From these data, the acceptability of all irradiated items was obtained. All ready-to-eat food items assayed like manioc flour, some pâtés and blocks of raw brown sugar and most of ready-to-eat meals like sausages and chicken with legumes were considered acceptable for microbial and sensory characteristics. On the other hand, the dehydrated food items chosen for this study, such as dehydrated bacon potatoes or pea soups were not accepted by the sensory analysis. A careful dose choice and special irradiation conditions must be used in order to achieve sensory acceptability needed for the commercialization of specific irradiated food items.

Inamura, Patricia Y.; Uehara, Vanessa B.; Teixeira, Christian A. H. M.; del Mastro, Nelida L.

2012-08-01

177

Sensitometry of the response of a new radiochromic film dosimeter to gamma radiation and electron beams  

Microsoft Academic Search

A new radiation-sensitive imaging material, called GafChromic™ Dosimetry Media, offers advances in high-dose radiation dosimetry and high-resolution radiography for gamma radiation and electrons. The potential uses in radiation processing, radiation sterilization of medical devices, population control of insects by irradiation, food irradiation, blood irradiation for organ-transplant immuno-suppression, clinical radiography, and industrial radiography have led to the present sensitometric study over

W. L. McLaughlin; Chen Yun-Dong; C. G. Soares; A. Miller; G. van Dyk; D. F. Lewis

1991-01-01

178

Airborne gamma-radiation survey of the Jabel Ishmas Quadrangle, Kingdom of Saudi Arabia  

USGS Publications Warehouse

An airborne gamma-radiation survey system, which includes digital recording and automatic data processing procedures developed by the U. S. Geological Survey Saudi Arabian Project, is used to collect spectral gamma-radiation data as an aid to regional geologic mapping of pediment areas on the Arabian Shield. The areal extent of rock units can generally be distinguished by the intensity of their radiation pattern. Rocks of ultramafic composition have low radiation response, whereas more felsic rocks reflect higher radiation response. Interpretations based on radiometric data enable the geologist to gain some understanding about the geologic setting of an area before he begins field mapping.

Flanigan, Vincent J.

1975-01-01

179

Chromosome fragility in New Zealand black mice: effect of ultraviolet and gamma radiations on fetal fibroblasts in vitro  

SciTech Connect

The sensitivity of fibroblasts cultured from New Zealand Black (NZB) and BALB/c mouse fetuses to uv and gamma radiations was tested with two methods: (1) colony-forming ability and (2) chromosome abnormalities. When compared with BALB/c cells, NZB cells had reduced colony-forming ability and increased chromosome abnormalities after uv irradiation. However, no differences were seen in colony formation or frequency of chromosome abnormalities between NZB and BALB/c cells after exposure to gamma radiation. This apparent uv specificity strengthens the suggestion that NZB mice might be used as a model to study the relationship between chromosome abnormalities and cancer in human syndromes such as xeroderma pigmentosum, which is characterized by chromosome instability.

Reddy, A.L. (Veterans Administration Hospital, Seattle, WA); Fialkow, P.J.

1980-04-01

180

THERMAL RADIATION FROM GAMMA-RAY BURST JETS  

SciTech Connect

In this study, the light curves and spectrum of the photospheric thermal radiation from ultrarelativistic gamma-ray burst (GRB) jets are calculated using two-dimensional relativistic hydrodynamic simulations of jets from a collapsar. As the jet advances, the density around the head of the jet decreases, and its Lorentz factor reaches as high as 200 at the photosphere and 400 inside the photosphere. For an on-axis observer, the photosphere appears concave due to the low density and high beaming factor of the jet. The luminosity varies because of the abrupt change in the position of the photosphere due to the internal structure of the jet. Comparing our results with GRB 090902B, the flux level of the thermal-like component is similar to our model, although the peak energy appears slightly higher (but still within a factor of two). From the comparison, we estimate that the bulk Lorentz factor of GRB 090902B is {Gamma} {approx} 2.4 x 10{sup 2}(r/10{sup 12} cm), where r is the radius of the photosphere. The spectrum for an on-axis observer is harder than that for an off-axis observer. There is a time lag of a few seconds for high energy bands in the light curve. This may be the reason for the delayed onset of GeV emission seen in GRB 080916C. The spectrum below the peak energy is a power law and the index is 2.3-2.6, which is softer than that of a single temperature Planck distribution but still harder than that of the typical value of the observed spectrum.

Mizuta, Akira [Theory Center, Institute of Particle and Nuclear Studies, KEK (High Energy Accelerator Research Organization), 1-1 Oho, Tsukuba 305-0801 (Japan); Nagataki, Shigehiro; Aoi, Junichi, E-mail: mizuta@post.kek.jp [Yukawa Institute for Theoretical Physics, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan)

2011-05-01

181

Gamma-ray Burst Prompt Emission: Jitter Radiation in Stochastic Magnetic Field Revisited  

Microsoft Academic Search

We revisit the radiation mechanism of relativistic electrons in the stochastic magnetic field and apply it to the high-energy emissions of gamma-ray bursts (GRBs). We confirm that jitter radiation is a possible explanation for GRB prompt emission in the condition of a large electron deflection angle. In the turbulent scenario, the radiative spectral property of GRB prompt emission is decided

Jirong Mao; Jiancheng Wang

2011-01-01

182

Improvement of microbiological safety of sous-vide meals by gamma radiation  

NASA Astrophysics Data System (ADS)

Experimental batches of smoked-cured pork in stewed beans sauce were inoculated with spores of psychrotrophic Bacillus cereus, more heat and radiation resistant than spores of non-proteolytic C. botulinum. After vacuum packaging, the meals were treated with combinations of pasteurizing heat treatments and gamma irradiation of 5kGy. Prior and after treatments, and periodically during storage at 10°C, total aerobic and total anerobic viable cell counts, and selectively, the viable cell counts of B. cereus and sulphite-reducing clostridia have been determined. The effects of the treatment order as well as addition of nisin to enhance the preservative efficiency of the physical treatments were also studied. Heat-sensitization of bacterial spores surviving irradiation occurred. The quality-friendly sous-vide cooking in combination with this medium dose gamma irradiation and/or nisin addition increased considerably the microbiological safety and the keeping quality of the meals studied. However, approx. 40% loss of thiamin content occurred as an effect of combination treatments, and adverse sensorial effects may also limit the feasible radiation doses or the usable concentrations of nisin.

Farkas, J.; Polyák-Fehér, K.; Andrássy, É.; Mészáros, L.

2002-03-01

183

KINETICS OF RADIATION-INDUCED HEMOLYSIS OF HUMAN RED BLOOD CELLS  

Microsoft Academic Search

The rate of hemolysis of red blood cells in aqueous suspension by gamma ; radiation was found to be dependent on absorbed dose. Red blood cells thus ; provide a relatively simple biological system for studying the efficiency of ; chemical compounds as radiation protective agents. Data are presented from ; measurements of the kinetics of radioinduced hemolysis of human

R. W. Henkens; D. R. Kalkwarf

1962-01-01

184

Use of a solar panel as a directionally sensitive large-area radiation monitor for direct and scattered x-rays and gamma-rays.  

PubMed

The characteristics of a 25.4 X 91 cm solar cell panel used as an x-ray and gamma-ray radiation monitor are presented. Applications for monitoring the primary x-ray beam are described at different values of operating currents and voltages as well as for directional dependence of scattered radiation. Other applications in gamma-ray radiography are also given. The detector showed linear response to both x-ray and gamma-ray exposures. The equipment is rigid, easy to use, relatively inexpensive and requires no power supply or any complex electronic equipment. PMID:2828276

Abdul-Majid, S

1987-01-01

185

Gamma Ray Telescope Senses High-Energy Radiation  

NSDL National Science Digital Library

This video from NASA describes the GLAST satellite, which is equipped with a gamma-ray telescope, and shares some background about the kinds of extreme universal phenomena indicated by the presence of gamma rays.

Wnet

2011-11-02

186

Radioimmunological study of regulation of insulin secrtion in the presence of acute radiation sickness. [Rats, gamma radiation  

Microsoft Academic Search

Rats were exposed to 750 R of gamma radiation and one group was given insulin subcutaneously during the period of hypercorticoidism and hyperglycemia. Rats were killed at intervals up to 10 days after irradiation and insulin was determined by radioimmunoassay. A table is presented to show effects of radiation on levels of corticosterone, glucose, and insulin at daily intervals. Results

Barkalaya

1977-01-01

187

Prompt gamma radiation as a new tool to measure reactor power  

NASA Astrophysics Data System (ADS)

A new method, based on reactor prompt gamma radiation detection, for reactor power measurement is introduced and validated. To verify, the ex-core gamma radiation spectrum from the Iranian Heavy Water Zero Power Reactor (HWZPR) were measured by HPGe and NaI detectors each suitably positioned. The collective prompt gamma count rates for all or for a portion of each of 2?×2? NaI detector spectra were obtained for seven power level readings from calibrated reactor power monitors. A good linear behavior was found between gamma count rate and reactor power. The method of calibrated prompt gamma reactor power determination is a stable and reliable tool, on-line, sensitive to sudden variation of power, working in pulse mode, increasing redundancy and diversity and so improving the reactor safety. The prompt gamma counting system can be adopted and installed in other nuclear reactors to measure power.

jalali, Majid; Abdi, Mohammad Reza; davati, Mojtaba Mostajabod

2013-10-01

188

Gamma radiation effect on gas production in anion exchange resins  

NASA Astrophysics Data System (ADS)

Radiation-induced decomposition of Amberlite IRA400 anion exchange resin in hydroxide form by gamma radiolysis has been studied at various doses in different atmospheres (anaerobic, anaerobic with liquid water, and aerobic). The effect of these parameters on the degradation of ion exchange resins is rarely investigated in the literature. We focused on the radiolysis gases produced by resin degradation. When the resin was irradiated under anaerobic conditions with liquid water, the liquid phase over the resin was also analyzed to identify any possible water-soluble products released by degradation of the resin. The main products released are trimethylamine (TMA), molecular hydrogen (H2g) and carbon dioxide (CO2g). TMA and H2g are produced in all the irradiation atmospheres. However, TMA was in gaseous form under anaerobic and aerobic conditions and in aqueous form in presence of liquid water. In the latter conditions, TMAaq was associated with aqueous dimethylamine (DMAaq), monomethylamine (MMAaq) and ammonia (NH). CO2g is formed in the presence of oxygen due to oxidation of organic compounds present in the system, in particular the degradation products such as TMAg.

Traboulsi, A.; Labed, V.; Dauvois, V.; Dupuy, N.; Rebufa, C.

2013-10-01

189

Application of Jitter Radiation: Gamma-Ray Burst Prompt Polarization  

NASA Astrophysics Data System (ADS)

A high degree of polarization of gamma-ray burst (GRB) prompt emission has been confirmed in recent years. In this paper, we apply jitter radiation to study the polarization feature of GRB prompt emission. In our framework, relativistic electrons are accelerated by turbulent acceleration. Random and small-scale magnetic fields are generated by turbulence. We further determine that the polarization property of GRB prompt emission is governed by the configuration of the random and small-scale magnetic fields. A two-dimensional compressed slab, which contains a stochastic magnetic field, is applied in our model. If the jitter condition is satisfied, the electron deflection angle in the magnetic field is very small and the electron trajectory can be treated as a straight line. A high degree of polarization can be achieved when the angle between the line of sight and the slab plane is small. Moreover, micro-emitters with mini-jet structures are considered to be within a bulk GRB jet. The jet "off-axis" effect is intensely sensitive to the observed polarization degree. We discuss the depolarization effect on GRB prompt emission and afterglow. We also speculate that the rapid variability of GRB prompt polarization may be correlated with the stochastic variability of the turbulent dynamo or the magnetic reconnection of plasmas.

Mao, Jirong; Wang, Jiancheng

2013-10-01

190

Hydrogel membranes of PVAl/ clay by gamma radiation  

NASA Astrophysics Data System (ADS)

In the last decades several studies concerning the new methods for drug delivery system have been investigated. A new field known as "smart therapy" involves devices and drug delivery systems to detect, identify and treat the site affected by the disease, not interfering with the biological system. Cutaneous Leishmaniasis is an endemic disease that is characterized by the development of single or multiple localized lesions on exposed areas of skin and one coetaneous treatment could be a potential solution. The aim of this study was to obtain polymeric hydrogel matrices of poly(vinylalcohol)(PVAl) and chitosan with inorganic nanoparticles, which can release a drug according to the need of the treatment of injury caused by leishmania on the skin. The hydrogels matrices were obtained with PVAl/ chitosan and PVAl/ chitosan 0.5; 1.0 and 1.5% laponite RD clay, crosslinked by ionizing gamma radiation with dose of 25 kGy. The techniques used for characterization were swelling, gel fraction, Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TGA). After synthesis, the samples were immersed in distilled water and weighed in periods of time until 60 h for the swelling determination. The obtained results have indicated that the swelling of the membranes increases with clay concentration, in consequence of ionic groups present in the clay.

de Oliveira, M. J. A.; Parra, D. F.; Amato, V. S.; Lugão, A. B.

2013-03-01

191

Corrosion of copper-based materials in gamma radiation  

SciTech Connect

The corrosion behaviors of pure copper (CDA 101), 7% aluminum-copper bronze (CDA 613) and 30% nickel-copper (CDA 715) are being studied in a gamma radiation field of 1 x 10{sup 5} R/h. These studies are in support of the Nevada Nuclear Waste Storage Investigations (NNWSI) Project, by Lawrence Livermore National Laboratory (LLNL), of copper-based materials for possible use in container systems for the permanent geologic burial of nuclear waste. Weight loss, tear drop (stressed), and crevice specimens of the three materials were exposed to water vapor-air atmospheres at 95{sup 0}C and 150{sup 0}C and to liquid water at 95{sup 0}C for periods of one, three, and six months. Longer exposures are in progress. Measurements include: changes in the chemical composition of the gas and water, specimen weight changes, oxide film weights, evidence of microcracking and crevice corrosion, and chemical composition of the oxide films by Auger electron spectroscopy and x-ray diffraction. Interim results show considerable pit and under-film corrosion of alloys CDA 613 and CDA 715. Uniform corrosion rates range from 0.012 mil/yr (0.30 {mu}m/yr) to 0.22 mil/yr (5.6 {mu}m/yr), based on specimen weight losses during six- and seven-month exposures. The time dependencies will be determined as more data become available.

Yunker, W.H.

1986-06-01

192

Comparison of environmental radiation dosimetry and. gamma. -ray spectroscopy  

SciTech Connect

During the period 1975-1980, direct radiation dose rates were measured at 16 fixed locations in the vicinity of the Joseph M. Farley Nuclear Plant, Houston County, AL, by exposure of TLDs which were read quarterly. The average quarterly dose rates using LiF chips varied widely over the 6-yr period and were divided into 2 distinct population groups of 4 and 2 yr each, corresponding to the vendor labs supplying and reading the TLDs. The simultaneous exposure of CaSO/sub 4/:Dy TLDs for 2 yr gave a third set of values which fell between the 2 LiF groups. During the period December 1976-November 1980, simultaneous pressurized ion chamber (PIC) and in situ Ge(Li) ..gamma..-ray spectroscopy measurements were made at the same locations at approximately 6-month intervals. The average PIC dose rate values were in good agreement with the average 2-yr LiF TLD values. Also, good agreement resulted from converting the in situ radioactivity values to dose rates using conversion values previously published. The natural radioactivity and fallout /sup 137/Cs in the soil showed little variation for a specific site, but varied widely between some sites. With the event of rain at the end of a long dry period, there was a large increase in /sup 214/Pb activity detected. Short half-life manmade radionuclides were seen for a few months following several atmospheric nuclear tests by the People's Republic of China.

Jackson, W.M.; Spaulding, J.D.; Noakes, J.E.; Murphy, G.L.

1985-06-01

193

Development of an alpha/beta/gamma detector for radiation monitoring.  

PubMed

For radiation monitoring at the site of nuclear power plant accidents such as Fukushima Daiichi, radiation detectors not only for gamma photons but also for alpha and beta particles are needed because some nuclear fission products emit beta particles and gamma photons and some nuclear fuels contain plutonium that emits alpha particles. We developed a radiation detector that can simultaneously monitor alpha and beta particles and gamma photons for radiation monitoring. The detector consists of three-layered scintillators optically coupled to each other and coupled to a photomultiplier tube. The first layer, which is made of a thin plastic scintillator (decay time: 2.4 ns), detects alpha particles. The second layer, which is made of a thin Gd(2)SiO(5) (GSO) scintillator with 1.5 mol.% Ce (decay time: 35 ns), detects beta particles. The third layer made of a thin GSO scintillator with 0.4 mol.% Ce (decay time: 70 ns) detects gamma photons. By using pulse shape discrimination, the count rates of these layers can be separated. With individual irradiation of alpha and beta particles and gamma photons, the count rate of the first layer represented the alpha particles, the second layer represented the beta particles, and the third layer represented the gamma photons. Even with simultaneous irradiation of the alpha and beta particles and the gamma photons, these three types of radiation can be individually monitored using correction for the gamma detection efficiency of the second and third layers. Our developed alpha, beta, and gamma detector is simple and will be useful for radiation monitoring, especially at nuclear power plant accident sites or other applications where the simultaneous measurements of alpha and beta particles and gamma photons are required. PMID:22128972

Yamamoto, Seiichi; Hatazawa, Jun

2011-11-01

194

Development of an alpha/beta/gamma detector for radiation monitoring  

NASA Astrophysics Data System (ADS)

For radiation monitoring at the site of nuclear power plant accidents such as Fukushima Daiichi, radiation detectors not only for gamma photons but also for alpha and beta particles are needed because some nuclear fission products emit beta particles and gamma photons and some nuclear fuels contain plutonium that emits alpha particles. We developed a radiation detector that can simultaneously monitor alpha and beta particles and gamma photons for radiation monitoring. The detector consists of three-layered scintillators optically coupled to each other and coupled to a photomultiplier tube. The first layer, which is made of a thin plastic scintillator (decay time: 2.4 ns), detects alpha particles. The second layer, which is made of a thin Gd2SiO5 (GSO) scintillator with 1.5 mol.% Ce (decay time: 35 ns), detects beta particles. The third layer made of a thin GSO scintillator with 0.4 mol.% Ce (decay time: 70 ns) detects gamma photons. By using pulse shape discrimination, the count rates of these layers can be separated. With individual irradiation of alpha and beta particles and gamma photons, the count rate of the first layer represented the alpha particles, the second layer represented the beta particles, and the third layer represented the gamma photons. Even with simultaneous irradiation of the alpha and beta particles and the gamma photons, these three types of radiation can be individually monitored using correction for the gamma detection efficiency of the second and third layers. Our developed alpha, beta, and gamma detector is simple and will be useful for radiation monitoring, especially at nuclear power plant accident sites or other applications where the simultaneous measurements of alpha and beta particles and gamma photons are required.

Yamamoto, Seiichi; Hatazawa, Jun

2011-11-01

195

Development of an alpha/beta/gamma detector for radiation monitoring  

SciTech Connect

For radiation monitoring at the site of nuclear power plant accidents such as Fukushima Daiichi, radiation detectors not only for gamma photons but also for alpha and beta particles are needed because some nuclear fission products emit beta particles and gamma photons and some nuclear fuels contain plutonium that emits alpha particles. We developed a radiation detector that can simultaneously monitor alpha and beta particles and gamma photons for radiation monitoring. The detector consists of three-layered scintillators optically coupled to each other and coupled to a photomultiplier tube. The first layer, which is made of a thin plastic scintillator (decay time: 2.4 ns), detects alpha particles. The second layer, which is made of a thin Gd{sub 2}SiO{sub 5} (GSO) scintillator with 1.5 mol.% Ce (decay time: 35 ns), detects beta particles. The third layer made of a thin GSO scintillator with 0.4 mol.% Ce (decay time: 70 ns) detects gamma photons. By using pulse shape discrimination, the count rates of these layers can be separated. With individual irradiation of alpha and beta particles and gamma photons, the count rate of the first layer represented the alpha particles, the second layer represented the beta particles, and the third layer represented the gamma photons. Even with simultaneous irradiation of the alpha and beta particles and the gamma photons, these three types of radiation can be individually monitored using correction for the gamma detection efficiency of the second and third layers. Our developed alpha, beta, and gamma detector is simple and will be useful for radiation monitoring, especially at nuclear power plant accident sites or other applications where the simultaneous measurements of alpha and beta particles and gamma photons are required.

Yamamoto, Seiichi [Kobe City College of Technology, 8-3, Gakuen-Higashi-machi, Nishi-ku, Kobe, 651-2194 (Japan); Hatazawa, Jun [Osaka University of Graduate School of Medicine, 2-2, Yamadaoka, Suita-shi, Osaka, 565-0871 (Japan)

2011-11-15

196

Determination of Canine Dose Conversion Factors in Mixed Neutron and Gamma Radiation Fields.  

National Technical Information Service (NTIS)

The primary objective of mixed-field neutron/gamma radiation dosimetry in canine irradiation experiments conducted at the Armed Forces Radiobiology Research Institute (AFRRI) is to determine the absorbed midline tissue dose (MLT) at the region of interest...

B. A. Torres R. C. Bhatt J. C. Myska B. K. Holland

1996-01-01

197

Effect of gamma Radiation on Chlorophylls Content, Net Photosynthesis and Respiration of Chlorella Pyrenoidosa.  

National Technical Information Service (NTIS)

The effect of five doses of gamma radiation: 10, 100, 500, 1000 and 5000 Gy on chlorophylls content, net photosynthesis and respiration of Chlorella pyrenoidosa was studied. A decrease in chlorophylls levels is produced after irradiation at 500, 1000 and ...

C. Martin J. Fernandez

1983-01-01

198

Effects of gamma Radiation on Lichens and Lichen-Forming Fungi and Algae.  

National Technical Information Service (NTIS)

Initial literature reports indicated that lichens were highly resistant to gamma radiation. A series of experiments were undertaken to determine why lichens were so resistant. In experiments with Cladonia mitis, C. sylvatica, C. verticillata, Parmelia sul...

F. H. Erbisch

1977-01-01

199

Effetti delle radiazioni (gamma) in film sottili di silicio amorfo idrogenato. (Effects of gamma radiations in hydrogenated amorphous silicon layers).  

National Technical Information Service (NTIS)

The behavior of hydrogenated amorphous silicon layers irradiated with a gamma ray source has been studied. The total dose was in the range 5 + 100k Gy. The dark current was used to investigate the time evolution. The recovery effect of radiation damage at...

S. Baccaro P. D'Atanasio G. Maiello M. Petti L. Schirone

1994-01-01

200

Standoff Performance of HPGe Detectors in Identification of Gamma-Ray Radiation Sources  

Microsoft Academic Search

The detection and identification of radiation sources at distances in the range of 15 meters or more is becoming increasingly important for illicit materials interdiction and the location of lost or orphan sources. In most locations, there is a considerable gamma-ray flux from natural background (NORM) and cosmic- induced nuclides. This gamma-ray flux varies with time, weather conditions, location, and

Ronald M. Keyser; Timothy R. Twomey; Sam Hitch

201

REVIEW ARTICLE: Semiconductor devices for gamma ray, X ray and nuclear radiation detection  

Microsoft Academic Search

The application of semiconductor devices to the detection and analysis of gamma ray, X-ray and nuclear radiations is outlined. After a brief discussion on semiconductor detector principles, including mode of operation, choice of material and energy resolution various types of semiconductor detector are described. The uses of semiconductor devices in the fields of nuclear particle counting and spectrometry, gamma spectrometry,

A. H. F. Muggleton

1972-01-01

202

Biological effect of gamma radiation on in vitro culture in rice.  

National Technical Information Service (NTIS)

Radiobiological effects of gamma radiation on different types of rice before or during in vitro culture, combined treatments of (sup 137)Cs (gamma)-rays and NaN(sub 3) on mature embryo culture, and irradiation on growth of calli derived from anther in ric...

Wang Cailian Xu Gang Shen Mei Chen Qiufang

1994-01-01

203

Gamma radiation dose rate in indoor, outdoor and underground atmosphere around Tehri dam project, Uttarakhand, India  

Microsoft Academic Search

The natural pollution level due to gamma radiation was measured in about 22 residential houses around the Tehri Dam Project\\u000a in Uttarakhand state by using Environmental Radiation Dosimeter. Both urban and rural houses were selected for the measurements.\\u000a The recorded gamma dose rate in indoor atmosphere was found to vary from 25.1 ?R\\/h to 67 ?R\\/h with a mean value

M. S. Negi; Yogesh Prasad; Ganesh Prasad; G. S. Gusain; Manjari Badoni; R. C. Ramola

2009-01-01

204

Accumulation of Mn(II) in Deinococcus radiodurans Facilitates GammaRadiation Resistance  

Microsoft Academic Search

Deinococcus radiodurans is extremely resistant to ionizing radiation. How this bacterium can grow under chronic gamma-radiation (50 Gy\\/hour) or recover from acute doses greater than 10 kGy is unknown. We show that D. radiodurans accumulates very high intracellular manganese and low iron levels compared to radiation sensitive bacteria, and resistance exhibits a concentration-dependent response to Mn(II). Among the most radiation-resistant

Michael J. Daly; E Gaidamakova; V Matrosova; A Vasilenko; M Zhai; Amudhan Venkateswaran; M Hess; M V. Omelchenko; Heather M. Kostandarithes; S Makarova; L. P. Wackett; Jim K. Fredrickson; D Ghosal

2004-01-01

205

RBE (relative biological effectiveness) of tritium beta radiation to gamma radiation and x-rays analyzed by both molecular and genetic methods  

SciTech Connect

The relative biological effectiveness (RBE) of tritium beta radiation to /sup 60/Co gamma radiation was determined using sex-linked recessive lethals (SLRL) induced in Drosophila melanogaster spermatozoa as the biological effect. The SLRL test, a measure of mutations induced in germ cells transmitted through successive generations, yields a linear dose-response curve in the range used in these experiments. From these ratios of the slopes of the /sup 3/H beta and the /sup 60/ Co gamma radiation linear dose response curves, an RBE of 2.7 is observed. When sources of error are considered, this observation suggests that the tritium beta particle is 2.7 /plus minus/ 0.3 times more effective per unit of energy absorbed in inducing gene mutations transmitted to successive generation than /sup 60/Co gamma radiation. Ion tracks with a high density of ions (high LET) are more efficient than tracks with a low ion density (low LET) in inducing transmissible mutations, suggesting interaction among products of ionization. Molecular analysis of x-ray induced mutations shows that most mutations are deletions ranging from a few base pairs as determined from sequence data to multi locus deletions as determined from complementation tests and Southern blots. 14 refs., 1 fig.

Lee, W.R.

1988-01-01

206

Thermal Radiation from Gamma-ray Burst Jets  

NASA Astrophysics Data System (ADS)

In this study, the light curves and spectrum of the photospheric thermal radiation from ultrarelativistic gamma-ray burst (GRB) jets are calculated using two-dimensional relativistic hydrodynamic simulations of jets from a collapsar. As the jet advances, the density around the head of the jet decreases, and its Lorentz factor reaches as high as 200 at the photosphere and 400 inside the photosphere. For an on-axis observer, the photosphere appears concave due to the low density and high beaming factor of the jet. The luminosity varies because of the abrupt change in the position of the photosphere due to the internal structure of the jet. Comparing our results with GRB 090902B, the flux level of the thermal-like component is similar to our model, although the peak energy appears slightly higher (but still within a factor of two). From the comparison, we estimate that the bulk Lorentz factor of GRB 090902B is ? ~ 2.4 × 102(r/1012 cm), where r is the radius of the photosphere. The spectrum for an on-axis observer is harder than that for an off-axis observer. There is a time lag of a few seconds for high energy bands in the light curve. This may be the reason for the delayed onset of GeV emission seen in GRB 080916C. The spectrum below the peak energy is a power law and the index is 2.3-2.6, which is softer than that of a single temperature Planck distribution but still harder than that of the typical value of the observed spectrum.

Mizuta, Akira; Nagataki, Shigehiro; Aoi, Junichi

2011-05-01

207

Protection effects of condensed bromoacenaphthylene on radiation deterioration of ethylene-propylene-diene rubber. [Gamma radiation  

SciTech Connect

As a continuation of a series of the studies on the flame and ..gamma..-radiation resistant modification of ethylene-propylene-diene rubber (EPDM), condensed bromoacenaphthylene (con-BACN) as a newly developed flame retardant was synthesized and its effects on the radiation resistance of EPDM were investigated. The radiation resistance evaluated by measuring tensile properties of irradiated sheets of 2 mm thick was found improved greatly by adding con-BACN together with ordinary rubber ingredients but decreased by decabromodiphenylether (DBDPE) that has bromins in aromatic rings as con-BACN. When EPDM sheets of 1 mm thick were irradiated in oxygen at a dose rate of 1 X 10/sup 5/ rad/h, the weight swelling ratio increased with increasing dose, indicating that oxidative main chain scission is predominant under the irradiation conditions. On the other hand, crosslinking was shown to be predominant in nitrogen. From the results of the swelling experiments with different additives, it was concluded that DBDPE accelerates both the main chain scission in oxygen and the crosslinking in nitrogen. In contrast to this, con-BACN reduced the chain scission in oxygen. This observation was accounted by the assumption that the influence of the oxidative chain scission is partly compensated by the concurrent crosslinking which takes place through additions of con-BACN to substrate polymers even in the presence of oxygen.

Morita, Y.; Hagiwara, M.; Kasai, N.

1982-09-01

208

RADIATIVE PROCESSES (TAU ---> MU GAMMA, MU ---> E GAMMA AND MUON G-2) AS PROBES OF ESSM / SO(10)  

SciTech Connect

The Extended Supersymmetric Standard Model (ESSM), motivated on several grounds, introduces two vectorlike families (16 + 16) of SO(10) with masses of order one TeV. It is noted that the successful predictions of prior work on fermion masses and mixings, based on MSSM embedded in SO(10), can be retained rather simply within the ESSM extension. These include an understanding of the smallness of V{sub cb} {approx} 0.04 and the largeness of {nu}{sub {mu}}-{nu}{sub {tau}} oscillation angle, sin{sup 2} 2{theta}{sub {nu}{sub {mu}}{nu}{sub {tau}}}{sup OSC} {approx} 1. We analyze the new contributions arising through the exchange of the vectorlike families of ESSM to radiative processes including {tau} {yields} {mu}{gamma}, {mu} {yields} e{gamma}, b {yields} s{gamma}, EDM of the muon and the muon (g-2). We show that ESSM makes significant contributions especially to the decays {tau} {yields} {mu}{gamma} and {mu} {yields} e{gamma} and simultaneously to muon (g-2). For a large and plausible range of relevant parameters, we obtain: a{sub {mu}}{sup ESSM} {approx} +(10-40) x 10{sup -10}, with a correlated prediction that {tau} {yields} {mu}{gamma} should be discovered with an improvement in its current limit by a factor of 3-20. The implications for {mu} {yields} e{gamma} are very similar. The muon EDM is within reach of the next generation experiments. Thus, ESSM with heavy leptons being lighter than about 700 GeV (say) can be probed effectively by radiative processes before a direct search for these vectorlike leptons and quarks is feasible at the LHC.

Pati, Jogesh C

2002-08-08

209

Modeling radiation-induced cell cycle delays  

Microsoft Academic Search

Ionizing radiation is known to delay the cell cycle progression. In particular after particle exposure significant delays\\u000a have been observed and it has been shown that the extent of delay affects the expression of damage, such as chromosome aberrations.\\u000a Thus, to predict how cells respond to ionizing radiation and to derive reliable estimates of radiation risks, information\\u000a about radiation-induced cell

Anna Ochab-Marcinek; Ewa Gudowska-Nowak; Elena Nasonova; Sylvia Ritter

2009-01-01

210

Inverse gamma ray dose rate effect in californium-252 RBE experiment with human T-1 cells irradiated in vitro  

Microsoft Academic Search

Metabolically deoxygenated suspensions of human T-1 cells were used to determine the RBE in hypoxia of low dose rate (LDR) Cf-252 radiation compared to LDR gamma radiation. Based upon the initial portion of the survival curves the RBE was 5.0 +- 1.0 for all components of the Cf-252 radiation and 7.1 +- 1.7 for the neutrons alone. An inverse dose

P. Todd; J. M. Feola

1986-01-01

211

Improvement of bacteriological quality of frozen chicken by gamma radiation.  

National Technical Information Service (NTIS)

The possible use of gamma irradiation at doses of 1.6 to 4.0 kGy to improve bacteriological quality of frozen chicken was investigated. The effects of gamma irradiation on salmonella viability in frozen chicken and on sensory quality of frozen chicken wer...

K. Nouchpramool Y. Prachasitthisak S. Charoen S. Kanarat K. Kanignunta

1986-01-01

212

MORPHOLOGICAL CHANGES PRODUCED BY GAMMA RADIATION ON THE SPOROGONOUS CYCLE OF PLASMODIUM GALLINACEUM  

Microsoft Academic Search

It has been shown that gamma radiation administered to the sporogonous ; cycle of the malarial parasite Plasmodium gallinaceum inhibits its normal ; development within the host mosquito Aedes aegypti. The morphological changes ; which occur in the parasite in vivo, as a consequence of the exposure to ; radiation, have been described in some detail, and are demonstrated in

Levon A. Terzian

1961-01-01

213

Protective effects of melatonin and vitamin E in brain damage due to gamma radiation  

Microsoft Academic Search

Gamma radiation is known to cause serious damage in the brain, and many agents have been used for neuroprotection. In this study, lipid peroxidation levels and histopathological changes in brain tissues of whole-body irradiated rats with likely radiation injury were compared to those with melatonin and vitamin E protection. Forty rats in four equal groups were used. The control group

Fatih S. Erol; Cahide Topsakal; M. Faik Ozveren; Metin Kaplan; Nevin Ilhan; I. Hanifi Ozercan; Oguz G. Yildiz

2004-01-01

214

Mold and aflatoxin reduction by gamma radiation of packed hot peppers and their evolution during storage.  

PubMed

The effect of gamma radiation on moisture content, total mold counts, Aspergillus counts, and aflatoxins of three hot pepper hybrids (Sky Red, Maha, and Wonder King) was investigated. Whole dried peppers packed in polyethylene bags were gamma irradiated at 0 (control), 2, 4, and 6 kGy and stored at 25°C for 90 days. Gamma radiation proved to be effective in reducing total mold and Aspergillus counts in a dose-dependent relationship. Total mold counts in irradiated peppers immediately after treatments were significantly lowered compared with those in nonirradiated samples, achieving 90 and 99% reduction at 2- and 4-kGy doses, respectively. Aspergillus counts were significantly reduced, by 93 and 97%, immediately after irradiation at doses of 2 and 4 kGy, respectively. A radiation dose of 6 kGy completely eliminated the population of total molds and Aspergillus fungi. The evolution of total molds in control and irradiated samples indicated no further fungal proliferation during 3 months of storage at 25°C. Aflatoxin levels were slightly affected by radiation doses of 2 and 4 kGy and showed a nonsignificant reduction of 6% at the highest radiation dose of 6 kGy. The distinct effectiveness of gamma radiation in molds and aflatoxins can be explained by the target theory of food irradiation, which states that the likelihood of a microorganism or a molecule being inactivated by gamma rays increases as its size increases. PMID:22856582

Iqbal, Qumer; Amjad, Muhammad; Asi, Muhammad Rafique; Ariño, Agustin

2012-08-01

215

Reflectivity of linear and nonlinear gamma radiated apodized chirped Bragg grating under ocean  

SciTech Connect

In this paper, the effect Co{sup 60} gamma radiation is investigated on the effective refractive index of apodized chirped Bragg grating. Nine apodization profiles are considered. Comparison between the reflectivity of the gamma radiated and non radiated fiber Bragg grating has been carried out. The electric field of signals propagating through the apodized chirped fiber Bragg grating (ACFBG) is first calculated from which, new values for the refractive index are determined. The nonlinear effects appear on the ACFBG reflectivity. The effect of nonlinearity and undersea temperature and pressure on the grating is also studied.

Hamdalla, Taymour A. [Faculty of Science, Alexandria University, Alexandria (Egypt); Faculty of Science, Tabuk University, Tabuk (Saudi Arabia)

2012-09-06

216

[Control of the main radiation parameters of a gamma teletherapy apparatus].  

PubMed

In radiotherapy a dosimetric method is used nowadays to control the magnitude of the radiation axis deviation from the isocenter (RL) of a gamma-beam therapeutic apparatus (gamma BTA). However, the use of the method requires special costly equipment. Besides, it is fairly laborious. The dosimetric method does not permit the measurement of the distance between the isocentre and the virtual source (DISvirt) A gamma-metric method of the RL and DISvirt control in the gamma BTA is described. It is based on the photogammametric treatment of a gamma-picture of a special test object. The method is marked by high accuracy and safety. In addition, the gamma BTA can also be used in operation of accelerating therapeutic units. PMID:2038255

Cherni?, A N; Va?nberg, M Sh

217

Snowpack snow water equivalent measurement using the attenuation of cosmic gamma radiation  

SciTech Connect

Incoming, background cosmic radiation constantly fluxes through the earth`s atmosphere. The high energy gamma portion of this radiation penetrates many terrestrial objects, including the winter snowpack. The attenuation of this radiation is exponentially related to the mass of the medium through which it penetrates. For the past three winters, a device measuring cosmic gamma radiation--and its attenuation through snow--has been installed at the Central Sierra Snow Laboratory, near Donner Pass, California. This gamma sensor, measuring energy levels between 5 and 15 MeV, has proved to be an accurate, reliable, non-invasive, non-mechanical instrument with which to measure the total snow water equivalent of a snowpack. This paper analyzes three winters` worth of data and discusses the physics and practical application of the sensor for the collection of snow water equivalent data from a remote location.

Osterhuber, R. [Univ. of California, Soda Springs, CA (United States). Central Sierra Snow Lab.; Fehrke, F. [California Dept. of Water Resources, Sacramento, CA (United States); Condreva, K. [Sandia National Labs., Livermore, CA (United States)

1998-05-01

218

60Co gamma radiation effect on AlGaN/AlN/GaN HEMT devices  

NASA Astrophysics Data System (ADS)

The testing techniques and experimental methods of the 60Co gamma irradiation effect on AlGaN/AlN/GaN high electron mobility transistors (HEMTs) are established. The degradation of the electrical properties of the device under the actual radiation environment are analyzed theoretically, and studies of the total dose effects of gamma radiation on AlGaN/AlN/GaN HEMTs at three different radiation bias conditions are carried out. The degradation patterns of the main parameters of the AlGaN/AlN/GaN HEMTs at different doses are then investigated, and the device parameters that were sensitive to the gamma radiation induced damage and the total dose level induced device damage are obtained.

Wang, Yan-Ping; Luo, Yin-Hong; Wang, Wei; Zhang, Ke-Ying; Guo, Hong-Xia; Guo, Xiao-Qiang; Wang, Yuan-Ming

2013-05-01

219

SOME ASPECTS OF THE DEGENERATION AND DEATH OF CELLS UNDER THE ACTION OF RADIATION  

Microsoft Academic Search

Biochemical and cytologic changes were investigated in yeast cells ; (Saccharomyces cerevisiae, Saccharomycodes ludwigii, Endomyces magnusii) exposed ; to Co⁶° gamma radiation at a dose rate of 90 r\\/sec. The cells in aqueous ; suspensions were given doses up to 1 Mrad. Threshold doses of the ; radiosensitivity of various cellular functions are given. The cells show a sharp ;

M. N. Meissel; G. A. Medvedeva; M. N. Poglazova

1961-01-01

220

What is the radiative process of the prompt phase of Gamma Ray Bursts?  

SciTech Connect

Despite the dramatic improvement of our knowledge of the phenomenology of Gamma Ray Bursts, we still do not know several fundamental aspects of their physics. One of the puzzles concerns the nature of the radiative process originating the prompt phase radiation. Although the synchrotron process qualifies itself as a natural candidate, it faces severe problems, and many efforts have been done looking for alternatives. These, however, suffer from other problems, and there is no general consensus yet on a specific radiation mechanism.

Ghisellini, G. [INAF-Osservatorio Astronomico di Brera, Via Bianchi 46 I-23807 Merate (Italy)

2010-07-15

221

Radiation chemistry of salt-mine brines and hydrates. [Gamma radiation  

SciTech Connect

Certain aspects of the radiation chemistry of NaCl-saturated MgCl/sub 2/ solutions and MgCl/sub 2/ hydrates at temperatures in the range of 30 to 180/sup 0/C were investigated through experiments. A principal objective was to establish the values for the yields of H/sub 2/ (G(H/sub 2/)) and accompanying oxidants in the gamma-ray radiolysis of concentrated brines that might occur in waste repositories in salt. We concluded that G(H/sub 2/) from gamma-irradiated brine solution into a simultaneously irradiated, deaerated atmosphere above the solution is between 0.48 and 0.49 over most of the range 30 to 143/sup 0/C. The yield is probably somewhat lower at the lower end of this range, averaging 0.44 at 30 to 45/sup 0/C. Changes in the relative amounts of MgCl/sub 2/ and NaCl in the NaCl-saturated solutions have negligible effects on the yield. The yield of O/sub 2/ into the same atmosphere averages 0.13, independent of the temperature and brine composition, showing that only about 50% of the radiolytic oxidant that was formed along with the H/sub 2/ was present as O/sub 2/. We did not identify the species that compose the remainder of the oxidant. We concluded that the yield of H/sub 2/ from a gamma-irradiated brine solution into a simultaneously irradiated atmosphere containing 5 to 8% air in He may be greater than the yield in deaerated systems by amounts ranging from 0% for temperatures of 73 to 85/sup 0/C, to about 30 and 40% for temperatures in the ranges 100 to 143/sup 0/C and 30 to 45/sup 0/C, respectively. We did not establish the mechanism whereby the air affected the yields of H/sub 2/ and O/sub 2/. The values found in this work for G(H/sub 2/) in deaerated systems are in approximate agreement with the value of 0.44 for the gamma-irradiation yield of H/sub 2/ in pure H/sub 2/O at room temperature. They are also in agreement with the values predicted by extrapolation from the findings of previous researchers for the value for G(H/sub 2/) in 2 M NaCl solutions at room temperature.

Jenks, G.H.; Walton, J.R.; Bronstein, H.R.; Baes, C.F. Jr.

1981-07-01

222

Investigation of {gamma} radiation from {sup 178}Hf in the respective (n, n Prime {gamma}) reaction  

SciTech Connect

The spectra and angular distributions of gamma rays were measured in the reaction {sup 178}Hf(n, n Prime {gamma}) induced by a beam of fast reactor neutrons. Data onmultipole mixtures in gamma transitions and a lot of new information about gamma transitions of energy 1.5 to 3.0 MeV were obtained. A comparison of these results with information known from the respective (n, {gamma}) reaction made it possible to refine the schemes of deexcitation of {sup 178}Hf levels at energies above 1.5 MeV, to determine more precisely features of these levels, and to introduce new levels and rotation bands at excitation energies of about 2MeV.

Govor, L. I.; Demidov, A. M.; Kurkin, V. A., E-mail: kurkin@polyn.kiae.su; Mikhailov, I. V. [National Research Center Kurchatov Institute (Russian Federation)

2012-12-15

223

Effects of gamma Radiation on Polymer Matrix Waste Forms.  

National Technical Information Service (NTIS)

A study has been made of the volume and weight changes, mechanical properties, and radiolytic gas production of polymer matrix waste forms during gamma irradiation in open containers. The work has been commissioned by the Department of the Environment as ...

D. I. Johnson S. G. Burnay D. C. Phillips

1986-01-01

224

METHOD AND APPARATUS FOR PRODUCING AND ANALYZING POLARIZED GAMMA RADIATION  

DOEpatents

A method of polarizing and resolving the plane of polarization of gamma rays is described. Polarization is produced by positioning a thin disc of ferromagnetic metal, cortaining /sup 57/Co, in a magnetic field. Resolution is accomplished by rotating a thin disc of iron enriched in /sup 57/Fe relative to a second magnetic field and noting the change of gamma absorption at each rotational position. (AEC)

Hamermesh, M.; Hanna, S.S.; Perlow, G.J.

1964-04-21

225

Gamma–delta T-cell-mediated dilated cardiomyopathy  

Microsoft Academic Search

Gamma–delta T-cells are usually minor component of peripheral blood and lymphoid tissues, but may play an important role in autoimmune diseases. We here describe the first case of dilated cardiomyopathy (DCM) with heart infiltration by mostly gamma–delta T-cells, who improved significantly by steroid therapy. In general, steroid therapy has only a little effect on DCM, however these findings might have

Norifumi Takeda; Yoshinori Seko; Noboru Oriuchi; Ryozo Nagai

2008-01-01

226

Features of the flux of gamma-radiation in the lower atmosphere during precipitation  

NASA Astrophysics Data System (ADS)

We are carrying out observations and studies of increases of gamma radiation intensity in a ground atmosphere layer during precipitations. Measurements have been carried out in two high-altitude points: Apatity (Murmansk) and Barentsburg (Spitsbergen). Scintillation detectors on the basis of NaI(Tl) crystals are used. Continuous radiation detection is made as the count rate in integral channels with threshold values >20 keV, >100 keV. There are more than 500 events of increase in gamma-ray background during precipitation. Average profiles of X-ray radiation increases in a ground level and the related with them increases of intensity of precipitations for stations in Apatity and Barentsburg have been built up. In Apatity the average increase profile in the gamma-ray flux and accompanying with profile of precipitations rate have been obtained. A time gap between peaks of precipitation and increase one is 30-40 minutes. A barometric coefficient of each component of radiation has been calculated. The barometric coefficient has a zero value on gamma-ray. The charged component of the secondary cosmic rays has a typical value ~0.18 %/mB. The lack of the barometric effect on gamma-ray indicates on the local origin of this radiation.

Germanenko, A. V.; Balabin, Yu V.; Gvozdevsky, B. B.; Vashenyuk, E. V.

2013-02-01

227

Radiation Damage to a Dynamic Cell Population  

Microsoft Academic Search

Models for ionizing radiation damage to cells are surveyed. Examples are given for how radiation damage models can be combined with those standard cell population dynamics models which have, in the absence of radiation, a time development governed by a semi-group of non-negative operators. Such combined models are useful in analyzing observed radiation dose-rate effects: direct dose-rate effects when protracting

P. Hahnfeldt; R. K. Sachs

228

Roles of ionizing radiation in cell transformation  

SciTech Connect

Earlier the authors described a repair misrepair model (RMR-I) which is applicable for radiations of low LET, e.g., x rays and gamma rays. RMR-II was described later. Here is introduced a mathematical modification of the RMR model, RMR-III, which is intended to describe lethal effects caused by heavily ionizing tracks. 31 references, 4 figures.

Tobias, C.A.; Albright, N.W.; Yang, T.C.

1983-07-01

229

Human Vdelta 2+\\\\ gamma delta T-Cell Tolerance to Foreign Antigens of Toxoplasma gondii  

Microsoft Academic Search

Little is known about the mechanisms involved in human gamma delta T-cell tolerance to self or to foreign antigens. Patients with congenital toxoplasmosis offer a unique opportunity to examine Vdelta 2+\\\\ gamma delta T-cell tolerance. Analysis of gamma delta T cells in patients with congenital toxoplasmosis revealed evidence for anergy of these cells with or without clonal Vdelta 2+\\\\ gamma

Toshiro Hara; Shizuko Ohashi; Yushiro Yamashita; Toshiaki Abe; Hajime Hisaeda; Kunisuke Himeno; Robert A. Good; Kenzo Takeshita

1996-01-01

230

INVESTIGATION OF EFFECTS OF RADIATION APPLICABLE AS GAMMA RADIATION DOSIMETERS. Period covered February 1957 through February 1958  

Microsoft Academic Search

This project was initiated to survey the field of radiation effects to ; determine which effects mmight be useful for high-level gamma dosimetry. ; Accordingly, the approach has been to survey the literature in broad areas and ; then to initiate experimental studies in those cases where additional information ; was required for evaluation of certain systems. It was not

J. F. Kircher; B. W. King; M. J. Oestmann; W. A. Hedden; J. H. Cahn; J. Moody; P. Schall; G. D. Calkins

1958-01-01

231

Radiation Exposure of the Population and Indoor Radiation Levels in The Netherlands Caused by Natural gamma Sources.  

National Technical Information Service (NTIS)

An estimate has been made of gamma doses to the population in the Netherlands, caused by natural radiation sources encountered in the environment. Data are given, derived from two independent types of measurements: 1. Exposure/dose rate measurements in th...

H. W. Julius R. Dongen

1985-01-01

232

A radiation transport model as a design tool for gamma densitometers  

Microsoft Academic Search

A flexible EGS4 Monte Carlo model was developed to simulate radiation transport in low-energy gamma-ray densitometers which are used for void (gas) fraction measurements in gas\\/liquid pipe flows. The detector responses produced by the model with 241Am gamma-ray input proved to be accurate in benchmarking experiments using real data. The verification was performed with homogeneous mixed flows at different void

E. Åbro; G. A. Johansen; H. Opedal

1999-01-01

233

X- and gamma-ray N+PP+ silicon detectors with high radiation resistance  

NASA Astrophysics Data System (ADS)

The paper describes some results concerning technology and behavior of x and gamma-ray N(superscript +)PP(superscript +) silicon detectors used in physics research, industrial and medical radiography and non-destructive testing. These detectors work at the room-temperature and can be used individually to detect x- and soft gamma-rays, or coupled with scintillators for higher incoming energies. Electrical characteristics of these photodiodes, their modification after exposure to radiation and results of spectroscopic x- and gamma-ray measurements are discussed. Devices manufactured under this technology proved to be stable after an exposure in high intensity gamma field with the dose range of 10 krad - 5 Mrad. Nuclear radiation resistance was studied by irradiation with (superscript 60)Co gamma source (1.17, 1.33 MeV) at dose rates of 59 krad/hour and 570 krad/hour. Results indicate that proposed structures enable the development of reliable silicon detectors to be used in high gamma-radiation environments encountered in a lot of applications.

Cimpoca, Valerica; Petris, Mariana; Ruscu, Radu; Breten, Madalina; Moraru, Rodica

1997-07-01

234

Gadolinium-doped water cerenkov-based neutron and high energy gamma-ray detector and radiation portal monitoring system  

DOEpatents

A water Cerenkov-based neutron and high energy gamma ray detector and radiation portal monitoring system using water doped with a Gadolinium (Gd)-based compound as the Cerenkov radiator. An optically opaque enclosure is provided surrounding a detection chamber filled with the Cerenkov radiator, and photomultipliers are optically connected to the detect Cerenkov radiation generated by the Cerenkov radiator from incident high energy gamma rays or gamma rays induced by neutron capture on the Gd of incident neutrons from a fission source. The PMT signals are then used to determine time correlations indicative of neutron multiplicity events characteristic of a fission source.

Dazeley, Steven A; Svoboda, Robert C; Bernstein, Adam; Bowden, Nathaniel

2013-02-12

235

Gamma radiation induced degradation in PE-PP block copolymer  

SciTech Connect

In the present investigation, effect of gamma irradiation on the PP-PE block copolymer has been studied. The polymer has been subjected to gamma irradiation from 100 to 500 Mrad dosages. Characterization of the polymer using XRD and FTIR was done both before irradiation and after irradiation in each step. Effect of irradiation on the electrical properties of the material has also been studied. FTIR study shows that the sample loses C - C stretching mode of vibration but gains C=C stretching mode of vibration after irradiation. Present investigation clearly indicates that though the electrical conductivity increases in the material, it undergoes degradation and shows brittleness due to irradiation.

Ravi, H. R.; Sreepad, H. R.; Ahmed, Khaleel; Govindaiah, T. N. [P.G. Department of Physics, Government College (Autonomous), Mandya - 571401, Karnataka State (India)

2012-06-05

236

Calibration of the maize yg2 assay using gamma radiation and ethylmethanesulfonate  

SciTech Connect

A standard protocol for the yellow-green-2 (yg2) forward mutation assay in Zea mays is proposed. A detailed calibration of the assay using /sup 137/Cs gamma rays and ethylmethanesulfonate (EMS) was conducted. Gamma ray-induced mutant sectors in leaves 4 and 5 exhibited one-hit kinetics. The radiation doses ranged from 25 to 500 rads. The mean induced mutation rate per rad of gamma radiation was 4.54 X 10/sup -6/. The induction of forward mutation by EMS also exhibited one-hit kinetics in the concentration range 0.25-20 mM. The mean induced mutation rate per mM EMS was 1.79 X 10/sup -4/, and the mean induced mutation rate per ..mu..mol of EMS per kernel was 1.52 X 10/sup -4/. Using the induced mutation rates for gamma radiation and EMS, the rad equivalent was calculated. One rad of gamma radiation is equivalent to the exposure of a 2.53 X 10/sup -5/ M EMS solution or to 2.99 X 10/sup -8/ mol of EMS per kernel.

Plewa, M.J.; Dowd, P.A.; Wagner, E.D.

1984-01-01

237

Interferon gamma inhibits apoptotic cell death in B cell chronic lymphocytic leukemia  

PubMed Central

The malignant, CD5+ B lymphocytes of B cell chronic lymphocytic leukemia (B-CLL) die by apoptosis in vitro. This is in contrast to the prolonged life span of the leukemic cells in vivo and likely reflects the lack of essential growth factors in the tissue culture medium. We found that interferon gamma (IFN-gamma) inhibits programmed cell death and promotes survival of B-CLL cells in culture. This effect may also be important in vivo: increased serum levels of IFN-gamma, ranging from 60 to > 2,200 pg/ml, were found in 7 of 10 B-CLL samples tested, whereas the sera of 10 healthy individuals did not contain detectable levels of this cytokine (< 20 pg/ml). High levels of IFN-gamma message were detected in RNA from T cell-depleted B-CLL peripheral blood samples by Northern blot analysis. Synthesis of IFN-gamma by B-CLL lymphocytes was confirmed by in situ hybridization and flow cytometry. The majority of B-CLL cells (74-82%) expressed detectable levels of IFN- gamma mRNA, and CD19+ B-CLL cells were labeled with anti-IFN-gamma monoclonal antibodies. These results show that IFN-gamma inhibits programmed cell death in B-CLL cells and suggest that the malignant cells are able to synthesize this cytokine. By delaying apoptosis, IFN- gamma may extend the life span of the malignant cells and thereby contribute to their clonal accumulation.

1993-01-01

238

Lunar radiation environment: a study by using Kaguya gamma-ray spectrometer and Monte Carlo simulation  

NASA Astrophysics Data System (ADS)

We have continued to improve the estimation of radiation dose on the Moon based on observation by remote sensing and calculation of the transportation of cosmic-ray particles in the lunar materials in order to provide basic data for a future manned lunar exploration. On the lunar surface, the dose of primary galactic cosmic rays (pGCR) is the most significant and the contributions of neutrons and gamma rays are relatively small and are approximately 10% and 1% of that of pGCR, respectively. However, these percentages are changed by use of thick shieldings and also geographical feature of the lunar surface, such as margin of a huge boulder, bottom of a pit, inside of a possible lava tube. In this case, the dose by pGCRs is moderated and the contributions of neutrons and gamma rays relatively increase. Here, we show the recent estimation of spatial variation of the lunar dose due to gamma ray and neutrons measured by Kaguya gamma-ray spectrometer. The energy spectrum of gamma rays from the lunar surface are precisely measured by a germanium (Ge) gamma-ray spectrometer onboard the Japanese lunar orbiter (Kaguya/SELENE). The flux of fast neutrons from the lunar surface was also measured by detecting the characteristic gamma rays due to the neutron inelastic reaction with the Ge of the spectrometer, that is 72Ge(n, n'g)72Ge. The estimation of radiation dose on the Moon based on Monte Carlo simulation will also be presented.

Kobayashi, Shingo; Hayatsu, Kanako; Uchihori, Yukio; Hareyama, Makoto; Hasebe, Nobuyuki; Fujibayashi, Yukari

2012-07-01

239

Ionizing Radiation Induces Stemness in Cancer Cells  

PubMed Central

The cancer stem cell (CSC) model posits the presence of a small number of CSCs in the heterogeneous cancer cell population that are ultimately responsible for tumor initiation, as well as cancer recurrence and metastasis. CSCs have been isolated from a variety of human cancers and are able to generate a hierarchical and heterogeneous cancer cell population. CSCs are also resistant to conventional chemo- and radio-therapies. Here we report that ionizing radiation can induce stem cell-like properties in heterogeneous cancer cells. Exposure of non-stem cancer cells to ionizing radiation enhanced spherogenesis, and this was accompanied by upregulation of the pluripotency genes Sox2 and Oct3/4. Knockdown of Sox2 or Oct3/4 inhibited radiation–induced spherogenesis and increased cellular sensitivity to radiation. These data demonstrate that ionizing radiation can activate stemness pathways in heterogeneous cancer cells, resulting in the enrichment of a CSC subpopulation with higher resistance to radiotherapy.

Ghisolfi, Laura; Keates, Andrew C.; Hu, Xingwang; Lee, Dong-ki; Li, Chiang J.

2012-01-01

240

Radiative higgs boson decays H {yields} f{anti f}{gamma}  

SciTech Connect

Higgs boson radiative decays of the form H {r_arrow} f{ovr f}{gamma} are calculated in the Standard Model using the complete one-loop expressions for the decay amplitudes. Contributions to the radiative width from leptons and light quarks are given. We also present e{ovr e} invariant mass distributions for H {r_arrow} e{ovr e}{gamma}, which illustrate the importance of the photon pole contribution and the effects of the box diagrams. 4 refs., 6 figs.

Abbasabadi, A. [Department of Physical Science, Ferris State Univ., Big Rapids, MI (United States). Coll. of Technology; Bowser-Chao, D.; Repko, W.W. [Michigan State Univ., East Lansing, MI (United States); Dicus, D.A. [Texas Univ., Austin, TX (United States). Center for Particle Physics

1996-10-10

241

Effective gamma-ray doses due to natural radiation from soils of southeastern Brazil  

SciTech Connect

We have used gamma-ray spectrometry to study the distribution of natural radiation from soils of southeastern Brazil: Billings reservoir, Sao Bernardo do Campo Parks, Diadema Parks, Interlagos region, Sao Paulo, and soil from Sao Paulo and Rio de Janeiro beaches. In most of the regions studied we have found that the dose due the external exposure to gamma-rays, proceeding from natural terrestrial elements, are between the values 0.3 and 0.6 mSv/year, established by the United Nations Scientific Committee on the Effects of Atomic Radiation.

Silveira, M. A. G.; Moreira, R. H.; Bellini, B. S. [Centro Universitario da FEI, Sao Bernardo do Campo, Sao Paulo (Brazil); Medina, N. H.; Aguiar, V. A. P. [Instituto de Fisica da Universidade de Sao Paulo, Sao Paulo (Brazil)

2010-08-04

242

Inactivation of aflatoxin B1 by using the synergistic effect of hydrogen peroxide and gamma radiation  

SciTech Connect

Inactivation of aflatoxin B1 was studied by using gamma radiation and hydrogen peroxide. A 100-krad dose of gamma radiation was sufficient to inactivate 50 micrograms of aflatoxin B1 in the presence of 5% hydrogen peroxide, and 400 krad was required for total degradation of 100 micrograms of aflatoxin in the same system. Degradation of aflatoxin B1 was confirmed by high-pressure liquid chromatographic and thin-layer chromatographic analysis. Ames microsomal mutagenicity test showed loss of aflatoxin activity. This method of detoxification also reduces the toxin levels effectively in artificially contaminated groundnuts.

Patel, U.D.; Govindarajan, P.; Dave, P.J. (M.S. Univ. of Baroda (India))

1989-02-01

243

Gamma-radiation induced interstrand cross-links in PNA:DNA heteroduplexes.  

PubMed

Peptide nucleic acids (PNAs) efficiently hybridize with DNA and are promoted as versatile gene-targeting analytical tools and pharmaceuticals. However, PNAs have never been exploited as radiopharmaceuticals, and radiation-induced physicochemical modifications of PNA:DNA heteroduplexes have not been studied. Drug- and radiation-induced creation of covalent cross-links in DNA obstruct crucial cell survival processes such as transcription and replication and are thus considered genotoxic events with a high impact in anticancer therapies. Here we report that gamma-irradiation of complementary PNA:DNA heteroduplexes, wherein the PNA contains l-lysine, free amino, or N-methylmorpholinium N- and C-capping groups, results in the formation of irreversible interstrand cross-links (ICL). The number of detected ICL corresponds to the number of available amino functional groups on the PNA. The effect of DNA sequence on the formation of ICL was studied by modifying the terminal nucleotides of the DNA oligonucleotide to create deletions and overhangs. The involvement of abasic sites (ABS) on the DNA strand in the cross-linking reaction was confirmed by independent experiments with synthetic ABS-containing oligonucleotides. Molecular modeling and molecular dynamics (MD) simulations were applied to elucidate the conformation of the N- and C-capping groups of the PNA oligomer and their interactions with the proximal terminus of the DNA. Good agreement between experimental and modeling results was achieved. Modeling indicated that the presence of positively charged capping groups on the PNA increases the conformational flexibility of the PNA:DNA terminal base pairs and often leads to their melting. This disordered orientation of the duplex ends provides conditions for multiple encounters of the short (amino) and bulky (Lys) side chains with nucleobases and the DNA backbone up to the third base pair along the duplex stem. Dangling duplex ends offer favorable conditions for increased accessibility of the radiation-induced free radicals to terminal nucleotides and their damage. It is suggested that the ICL are produced by initial formation of Schiff base adducts between the PNA amino functions and the opposed DNA oxidation-damaged bases or abasic 2'-deoxyribose-derived aldehydic groups. The subsequent reduction by solvated electrons (e(-)(aq)) or other radiation-produced reducing species results in irreversible covalent interstrand cross-links. The simultaneous involvement of oxidizing, (*)OH, and reducing, e(-)(aq), radicals presents a case in which multiple ionization events along a gamma-particle path lead to DNA injuries that also encompass ICL as part of the multiply damaged sites (MDS). The obtained results may find applications in the development of a new generation of gene-targeted radiosensitizers based on PNA vectors. PMID:19469551

Gantchev, Tsvetan G; Girouard, Sonia; Dodd, David W; Wojciechowski, Filip; Hudson, Robert H E; Hunting, Darel J

2009-07-28

244

Gamma Radiation Effects on Tritium Permeation Through Stainless Steel.  

National Technical Information Service (NTIS)

It was found that in the presence of excess H sub 2 , the higher gamma-irradiation intensity exhibited slightly higher permeation rates of tritium. When the walls of the permeation tube and the HT were highly oxidized, the permeation rates were much more ...

G. R. Longhurst G. A. Deis P. Y. Hsu L. G. Miller R. A. Causey

1983-01-01

245

Radiation-Induced Edema after Gamma Knife Treatment for Meningiomas  

Microsoft Academic Search

A retrospective study was performed to analyze some parameters in a consecutive series of 35 Gamma Knife treatments in 34 patients with benign meningiomas. The minimum dose to the tumors was never less than 12 Gy. The follow-up period was from 1 to 3 years. A semiquantitative method of tumor volume assessment was used to measure the tumor response to

J. C. Ganz; O. Schröttner; G. Pendl

1996-01-01

246

Neutron and gamma radiation effects in proton exchanged optical waveguides.  

PubMed

The effect of neutron and gamma ray irradiations on the optical properties of proton exchanged Z-cut lithium niobate optical planar waveguides were investigated. The damage thresholds were found by optical characterization for waveguides exchanged either in pure or diluted proton source. PMID:19451950

Passaro, Vittorio; Armenise, Mario

2002-09-01

247

Production of hydrogel wound dressings using gamma radiation  

Microsoft Academic Search

Hydrogel wound dressings have been prepared using the gamma rays irradiation technique. The dressings are composed of poly(vinyl pyrrolidone) (PVP), poly(ethylene glycol) (PEG) and agar. The influence of some process parameters on the properties of the dressings has been investigated as: the gel fraction, maximum swelling, swelling kinetics, and mechanical properties. The gel fraction increases with increasing PVP concentration due

Z. Ajji; I. Othman; J. M. Rosiak

2005-01-01

248

Cosmic gamma Radiation of Ultra High Energy of Primordial Origin.  

National Technical Information Service (NTIS)

The quantum mechanical effects near a collapsing black hole as shown by Stephen W. Hawking in 1974 to produce streaming particles through tunneling effect was explored in the context of cosmic gamma ray production. In this thesis, we show the possible pro...

1984-01-01

249

Application of Gamma-Ray Diffusion Theory to Radiation Dosimetry.  

National Technical Information Service (NTIS)

The diffusion equation governing gamma-ray transport has been evaluated in this study by means of random sampling and records of photon trajectories in tissue-like materials obtained for photon sources ranging in energy from 20 to 2750 keV. The records of...

W. H. Ellett

1969-01-01

250

RADIATION-INDUCED CHROMOSOME ABERRATIONS IN HUMAN FETAL CELLS GROWN IN VITRO  

Microsoft Academic Search

Diploid human cells (from fetal lung and brain) grown in. vitro were ; irradiated with Co⁶° gamma rays. The effect of radiation was measured by ; recording postmetaphase chromosomal aberrations in cell cultures fixed and ; stained 24 and 48 hr after acute irradiation. Spontaneous aberration frequencies ; were determined in matched control cultures. The frequency of spontaneous ; aberrations

Boeok

1962-01-01

251

Attenuation of VHE Gamma Rays by the Milky Way Interstellar Radiation Field  

SciTech Connect

The attenuation of very high energy gamma rays by pair production on the Galactic interstellar radiation field has long been thought of as negligible. However, a new calculation of the interstellar radiation field consistent with multi-wavelength observations by DIRBE and FIRAS indicates that the energy density of the Galactic interstellar radiation field is higher, particularly in the Galactic center, than previously thought. We have made a calculation of the attenuation of very high energy gamma rays in the Galaxy using this new interstellar radiation field which takes into account its nonuniform spatial and angular distributions. We find that the maximum attenuation occurs around 100 TeV at the level of about 25% for sources located at the Galactic center, and is important for both Galactic and extragalactic sources.

Moskalenko, Igor V.; /Stanford U., HEPL; Porter, Troy A.; /Louisiana State U.; Strong, Andrew W.; /Garching, Max Planck Inst., MPE

2006-04-19

252

Quercetin ameliorates gamma radiation-induced DNA damage and biochemical changes in human peripheral blood lymphocytes  

Microsoft Academic Search

We investigated the radioprotective efficacy of quercetin (QN), a naturally occurring flavonoid against gamma radiation-induced damage in human peripheral blood lymphocytes and plasmid DNA. In plasmid study, QN at different concentrations (3, 6, 12, 24 and 48?M) were pre-incubated with plasmid DNA for 1h followed by exposure of 6Gy radiation. Among all concentrations of QN used, 24?M showed optimum radioprotective

Nagarajan Devipriya; Adluri Ram Sudheer; Marimuthu Srinivasan; Venugopal P. Menon

2008-01-01

253

Effect of gamma radiation on the characteristics of gallium nitride HEMT heterostructures  

Microsoft Academic Search

The influence of gamma radiation from a Co60 source on some characteristics of AlGaN\\/GaN HEMT heterostructures has been studied. The dose dependence of the total source\\u000a and drain resistances is determined using a modified graphical-analytical method for calculation of the characteristic resistances\\u000a of HEMTs. The contacts exhibit a significant radiation-stimulated degradation, which detrimentally affects the transistor\\u000a operation and may account

A. M. Kurakin

2003-01-01

254

Gamma radiation-induced heritable mutations at repetitive DNA loci in out-bred mice  

Microsoft Academic Search

Recent studies have shown that expanded-simple-tandem-repeat (ESTR) DNA loci are efficient genetic markers for detecting radiation-induced germline mutations in mice. Dose responses following irradiation, however, have only been characterized in a small number of inbred mouse strains, and no studies have applied ESTRs to examine potential modifiers of radiation risk, such as adaptive response. We gamma-irradiated groups of male out-bred

C. M. Somers; R. Sharma; J. S. Quinn; D. R. Boreham

2004-01-01

255

Radiation detection system for portable gamma-ray spectroscopy  

DOEpatents

A portable gamma ray detection apparatus having a gamma ray detector encapsulated by a compact isolation structure having at least two volumetrically-nested enclosures where at least one is a thermal shield. The enclosures are suspension-mounted to each other to successively encapsulate the detector without structural penetrations through the thermal shields. A low power cooler is also provided capable of cooling the detector to cryogenic temperatures without consuming cryogens, due to the heat load reduction by the isolation structure and the reduction in the power requirements of the cooler. The apparatus also includes a lightweight portable power source for supplying power to the apparatus, including to the cooler and the processing means, and reducing the weight of the apparatus to enable handheld operation or toting on a user's person.

Rowland, Mark S. (Alamo, CA); Howard, Douglas E. (Livermore, CA); Wong, James L. (Dublin, CA); Jessup, James L. (Tracy, CA); Bianchini, Greg M. (Livermore, CA); Miller, Wayne O. (Livermore, CA)

2006-06-20

256

Multilayer optics for x-ray and gamma radiation  

Microsoft Academic Search

We report the experimental results on production of multilayer soft x-ray and EUV mirrors and their application in x-ray spectroscopy and fluorescence analysis, as well as for development of EUV lithographic and x-ray microscopic devices and soft x-ray point sources. The problem of the production and the investigation of short-period x-ray multilayers and multilayer (gamma) -filters is discussed.

S. S. Andreev; Sergey V. Gaponov; Nikolai N. Salashchenko; E. A. Shamov; Leonid A. Shmaenok; S. V. Bobashev; D. M. Simanovskii; Eugene N. Ragozin

1998-01-01

257

Measurement of gamma radiation levels in soil samples from Thanjavur using gamma-ray spectrometry and estimation of population exposure.  

PubMed

This study assesses the level of terrestrial gamma radiation and associated dose rates from the naturally occurring radionuclides (232)Th, (238)U and (40)K in 10 soil samples collected from Thanjavur (Tamil Nadu, India) using gamma-ray spectrometry. The activity profile of radionuclides has clearly showed the existence of low level activity in Thanjavur. The geometric mean activity concentrations of (232)Th, (238)U and (40)K is 42.9+/-9.4 Bq.kg(-1), 14.7+/-1.7 Bq.kg(-1) and 149.5+/-3.1 Bq.kg(-1) respectively are derived from all the soil samples studied. The activity concentration of (232)Th, (238)U and (40)K in soil is due to the presence of metamorphic rocks like shale, hornblende-biotite gneiss and quartzofeldspathic gneiss in these areas. Gamma absorbed dose rates in air outdoors were calculated to be in the range between 32 nGy.h(-1) and 59.1 nGy.h(-1) with an arithmetic mean of 43.3 +/-9 nGy.h(-1). This value is lesser than the population weighted world-averaged of 60 nGy.h(-1). Inhabitants of Thanjavur are subjected to external gamma radiation exposure (effective dose) ranging between 39.2 and 72.6 muSv.y(-1) with an arithmetic mean of 53.1+/-11 muSv.y(-1). The values of the external hazard index determined from the soil radioactivity of the study area are less than the recommended safe levels. PMID:20177570

Senthilkumar, B; Dhavamani, V; Ramkumar, S; Philominathan, P

2010-01-01

258

Naturally induced secondary radiation in interplanetary space: Preliminary analyses for gamma radiation and radioisotope production from thermal neutron activation  

NASA Astrophysics Data System (ADS)

Thermal neutron activation analyses were carried out for various space systems components to determine gamma radiation dose rates and food radiation contamination levels. The space systems components selected were those for which previous radiation studies existed. These include manned space vehicle radiation shielding, liquid hydrogen propellant tanks for a Mars mission, and a food supply used as space vehicle radiation shielding. The computational method used is based on the fast neutron distribution generated by the BRYNTRN and HZETRN transport codes for Galactic Cosmic Rays (GCR) at solar minimum conditions and intense solar flares in space systems components. The gamma dose rates for soft tissue are calculated for water and aluminum space vehicle slab shields considering volumetric source self-attenuation and exponential buildup factors. In the case of the lunar habitat with regolith shielding, a completely exposed spherical habitat was assumed for mathematical convenience and conservative calculations. Activation analysis of the food supply used as radiation shielding is presented for four selected nutrients: potassium, calcium, sodium, and phosphorus. Radioactive isotopes that could represent a health hazard if ingested are identified and their concentrations are identified. For nutrients soluble in water, it was found that all induced radioactivity was below the accepted maximum permissible concentrations.

Plaza-Rosado, Heriberto

1991-09-01

259

Papain incorporated chitin dressings for wound debridement sterilized by gamma radiation  

NASA Astrophysics Data System (ADS)

Wound debridement is essential for the removal of necrotic or nonviable tissue from the wound surface to create an environment conducive to healing. Nonsurgical enzymatic debridement is an attractive method due to its effectiveness and ease of use. Papain is a proteolytic enzyme derived from the fruit of Carica papaya and is capable of breaking down a variety of necrotic tissue substrates. The present study was focused on the use of gamma radiation for sterilization of papain dressing with wound debriding activity. Membranes with papain were prepared using 0.5% chitin in lithium chloride/dimethylacetamide solvent and sterilized by gamma radiation. Fluid absorption capacity of chitin-papain membranes without glycerol was 14.30±6.57% in 6 h. Incorporation of glycerol resulted in significant (p<0.001) increase in the absorption capacity. Moisture vapour transmission rate of the membranes was 4285.77±455.61 g/m2/24 h at 24 h. Gamma irradiation at 25 kGy was found suitable for sterilization of the dressings. Infrared (IR) spectral scanning has shown that papain was stable on gamma irradiation at 25-35 kGy. The irradiated chitin-papain membranes were impermeable to different bacterial strains and also exhibited strong bactericidal action against both Gram-positive and Gram-negative bacteria. The fluid handling characteristics and the antimicrobial properties of chitin-papain membranes sterilized by gamma radiation were found suitable for use as wound dressing with debriding activity.

Singh, Durgeshwer; Singh, Rita

2012-11-01

260

Influence of gamma-radiation on the nutritional and functional qualities of lotus seed flour.  

PubMed

In the present study, we investigated the physicochemical and functional properties of lotus seed flour exposed to low and high doses of gamma-radiation (0-30 kGy; the dose recommended for quarantine and hygienic purposes). The results indicated raw seed flour to be rich in nutrients with minimal quantities of antinutritional factors. Irradiation resulted in a dose-dependent increase in some of the proximal constituents. The raw and gamma-irradiated seeds meet the Food and Agricultural Organization-World Health Organization recommended pattern of essential amino acids. Some of the antinutritional factors (phytic acid, total phenolics, and tannins) were lowered with gamma-irradiation, while the seed flours were devoid of lectins, L-3,4-dihydroxyphenylalanine, and polonium-210. The functional properties of the seed flour were significantly improved with gamma-radiation. gamma-radiation selectively preserved or improved the desired nutritional and functional traits of lotus seeds, thus ensuring a safe production of appropriate nutraceutically valued products. PMID:19778060

Bhat, Rajeev; Sridhar, Kandikere Ramaiah; Karim, Alias A; Young, Chiu C; Arun, Ananthapadmanabha B

2009-10-28

261

Human gamma delta T cells: candidates for the development of immunotherapeutic strategies.  

PubMed

A numerically small subset of human T lymphocytes expresses a gamma delta T cell receptor (TCR). These gamma delta T cells share certain effector functions with alpha beta T cells as well as with NK cells and NKT cells. The major peripheral blood gamma delta T cell subset in healthy adults expresses a Vgamma9Vdelta2 TCR, which recognizes small phosphorylated metabolites referred to as phosphoantigens. Vdelta1 gamma delta T cells mainly occur in the intestine. They recognize the stress-induced MICA/B and CD1c. Furthermore, gamma delta T cells express a variety of NK cell and pattern-recognition receptors which are responsible for the "fine-tuning" of effector functions. In recent years, gamma delta T cells start to emerge as a rewarding target for immunotherapeutic strategies against viral infections and cancer. A better understanding of factors that modulate gamma gamma delta T cell function will further eluminate the potential of these cells. PMID:17695246

Beetz, Susann; Marischen, Lothar; Kabelitz, Dieter; Wesch, Daniela

2007-01-01

262

Results of Calculations of External gamma Radiation Exposure Rates from Local Fallout and the Related Radionuclide Compositions of Selected US Pacific Events.  

National Technical Information Service (NTIS)

This report presents data on calculated gamma radiation exposure rates and local surface deposition of related radionuclides resulting from selected US Pacific events. Results of the calculations of relative external gamma radiation exposure rate and rela...

H. G. Hicks

1984-01-01

263

Californium252 ( 252 Cf) versus Conventional Gamma Radiation in the Brachytherapy of Advanced Cervical Carcinoma  

Microsoft Academic Search

Background: When photon radiotherapy is applied to cervical carcinoma, it has been observed that, despite important progress in radiotherapy technique and quality assurance, no significant increase in curative rates has resulted. Among the reasons for this is the varying radiosensitivity of different tumor subpopulations. Treatment with californium-252 (252Cf), as a source of gamma\\/neutron radiation in brachytherapy, provides properties and new

Ta?o Ta?ev; Blanka Ptá?ková; Vratislav Strnad

2003-01-01

264

CALIBRATION AND USE OF A SYSTEM OF FILM BADGES FOR PERSONAL DOSIMETRY FOR GAMMA RADIATION  

Microsoft Academic Search

A method of calibration of a film-badge system for gamma radiations from ; radioisotopes is described. The criteria for the choice of emulsion and the ; system adopted for correcting the response from the energy dependence are shown. ; The energy dependence is corrected by a metallic filter, made by 1 mm of tin and ; 0.5 mm of lead

P. Amadesi; N. Grimellini; G. Guenzi; O. Rimondi

1959-01-01

265

The production and composition of rat sebum is unaffected by 3 Gy gamma radiation  

PubMed Central

Purpose The aim of this work was to use metabolomics to evaluate sebum as a source of biomarkers for gamma-radiation exposure in the rat, and potentially in man. Proof of concept of radiation metabolomics was previously demonstrated in both mouse and rat urine, from the radiation dose- and time-dependent excretion of a set of urinary biomarkers. Materials and methods Rats were gamma-irradiated (3 Gy) or sham irradiated and groups of rats were euthanised at 1 h or 24 h post-irradiation. Sebum was collected by multiple washings of the carcasses with acetone. Nonpolar lipids were extracted, methylated, separated and quantitated using gas chromatography-mass spectrometry (GCMS). Metabolomic analysis of the GCMS data was performed using both orthogonal projection to latent structures-discriminant analysis and random forests machine learning algorithm. Results Irradiation did not alter sebum production. A total of 35 lipids were identified in rat sebum, 29 fatty acids, five fatty aldehydes, and cholesterol. Metabolomics showed that three fatty acids, palmitic, 2-hydroxypalmitic, and stearic acids were potential biomarkers. Sebaceous palmitic acid was marginally statistically significantly elevated (7.5–8.4%) at 24 h post-irradiation. Conclusions Rat sebaceous gland appears refractory to 3 Gy gamma-irradiation. Unfortunately, collection of sebum shortly after gamma-irradiation is unlikely to form the basis of high-throughput non-invasive radiation biodosimetry in man.

Lanz, Christian; Ledermann, Monika; Slavik, Josef; Idle, Jeffrey R.

2013-01-01

266

Effect of Gamma and UV Radiation on Properties of EPDM\\/GTR\\/HDPE Blends  

Microsoft Academic Search

Ethylene propylene dine monomer (EPDM) was blended with both ground tire rubber (GTR) and high-density polyethylene (HDPE) prepared at different ratios and then exposed to gamma and ultraviolet radiations. The mechanical, physical, and thermal properties were investigated with respect to the kind of irradiation and blend compositions. A scanning electron microscope was also used to examine the morphology of the

M. M. Abou Zeid; S. T. Rabie; A. A. Nada; A. M. Khalil; R. H. Hilal

2008-01-01

267

An integrated systems approach for understanding cellular responses to gamma radiation  

Microsoft Academic Search

Cellular response to stress entails complex mRNA and protein abundance changes, which translate into physiological adjustments to maintain homeostasis as well as to repair and minimize damage to cellular components. We have characterized the response of the halophilic archaeon Halobacterium salinarum NRC-1 to 60Co ionizing gamma radiation in an effort to understand the correlation between genetic information processing and physiological

Kenia Whitehead; Adrienne Kish; Min Pan; Amardeep Kaur; David J Reiss; Nichole King; Laura Hohmann; Jocelyne DiRuggiero; Nitin S Baliga

2006-01-01

268

Stimulation Effects of gamma Radiation on Mung Bean (Vigna Radiata (L) Wilzcek).  

National Technical Information Service (NTIS)

Mung bean seeds of U-Thong 1 variety were treated with gamma radiation at different doses 0, 5, 10, 15, 20, 25, 30, 50, 75, 100, 200 and 400 gray respectively. Their germination, growth and yield were observed in a greenhouse and in a field. Their chromos...

V. Phadvibulya N. Vanichvattanaramlug S. Pichitporn

1983-01-01

269

Gamma radiation effects on physical properties of parchment documents: Assessment of Dmax  

NASA Astrophysics Data System (ADS)

Parchments are important documents that give testimony for History; therefore these materials should be respected and preserved. Considering incremental biodeterioration problems that have to be faced daily, the Archive of the University of Coimbra (AUC) is involved in different scientific projects in order to evaluate and determine new methods for document decontamination and preservation.The aim of this study was to evaluate gamma radiation effects on the colour and texture of the AUC parchment documents. The assessment of these effects was used to estimate the maximum gamma radiation dose (Dmax) that could guarantee parchment documents? decontamination treatment, without significant alteration of their physical properties. Parchment samples were exposed to gamma radiation doses ranging from 10 to 30 kGy. The texture and colour of samples were assessed before and after the irradiation procedure, using a texture analyser and an electronic colorimeter. Hardness and springiness were determined based on texture spectra. Lightness (L*), Chroma (C), greenness vs. redness (a*) and yellowness vs. blueness (b*) values were obtained from colorimetric measures. Results indicate no significant effects of gamma radiation on the texture and colour of parchment for the studied doses.

Nunes, Inês; Mesquita, Nuno; Cabo Verde, Sandra; João Trigo, Maria; Ferreira, Armando; Manuela Carolino, Maria; Portugal, António; Luísa Botelho, Maria

2012-12-01

270

Caffeic acid protects human peripheral blood lymphocytes against gamma radiation-induced cellular damage.  

PubMed

In the present study, we investigated in vitro radioprotective potential of caffeic acid (CA), a naturally occurring catecholic acid against gamma radiation-induced cellular changes. Different concentrations of CA (5.5, 11, 22, 44, 66, and 88 microM) were incubated with lymphocytes for 30 min prior to gamma-irradiation, and micronuclei (MN) scoring and comet assay were performed to fix the effective concentration of CA against gamma-irradiation. Among all concentrations, 66 microM of CA showed the optimum protection by effectively decreasing the MN frequencies and comet attributes. From the above-mentioned results, 66 microM of CA was selected as the effective concentration and was further used to investigate its radioprotective efficacy. For that purpose, a separate experiment was carried out on the lymphocytes in which lymphocytes were preincubated with CA (66 microM) and were exposed to different doses of radiation (1, 2, 3, and 4 Gy). Genetic damage (MN, dicentric aberration, and comet attributes) and biochemical changes were measured. Gamma-irradiated lymphocytes showed a dose-dependent increase in the genetic damage and thiobarbituric acid reactive substances, accompanied by the significant decrease in the antioxidant status, whereas CA pretreatment positively modulated all the radiation-induced changes through its antioxidant potential. The current study demonstrates that CA is effective in protecting lymphocytes against radiation-induced toxicity and encourages further in vivo study to evaluate radioprotective efficacy of CA. PMID:18561333

Devipriya, Nagarajan; Sudheer, Adluri Ram; Menon, Venugopal P

271

Study on the effect of low doses gamma radiation on mushroom spawn.  

National Technical Information Service (NTIS)

Mushroom spawn (Hybrid-521) was irradiated at room temperature using low doses of gamma radiation (50-600 rad). The spawn was then planted at two stages; first, after 24 hours of irradiation, and second after storage for three weeks at refrigeration tempe...

S. Ajlouni

1993-01-01

272

Split-sting trait in Apis mellifera induced by cobalt 60 gamma radiation.  

National Technical Information Service (NTIS)

The Split-Sting (SS) trait in honey bees, induced by gamma radiation, was discovered by Soares (1975). Bees with this trait are unable to sting, because the parts that compose the sting are separated. Many studies have been done in order to understand thi...

V. L. M. Silva

1993-01-01

273

Use of PCR for Detecting Aspergillus flavus in Maize Treated by Gamma Radiation Process  

Microsoft Academic Search

The aim of this study was to verify the effects of gamma radiation process on the fungal DNA and the application of PCR in the detection of Aspergillus flavus in irradiated maize grains. The samples were inoculated with a toxigenic strain and incubated under controlled conditions of relative humidity, water activity, and temperature for 15 days. After incubation, the samples

Simone Aquino; Ralf Greiner; Ursula Konietzny; Regina H. Hassegawa; Tatiana Alves dos Reis; Benedito Corrêa; Anna Lucia C. H. Villavicencio

2008-01-01

274

Effects of gamma radiation on a plastic material based on bean protein  

Microsoft Academic Search

The effect of gamma radiation applied to a system used for the preparation of biodegradable plastics was studied. The system was composed of the proteins and glucopolysaccharides previously isolated from Phaseolus vulgaris beans, mixed with glycerol and water as plasticizers. The irradiation of mixtures with doses of 25, 50 and 100 kGy was carried out in two conditions: (a) before

M. E. Gonzalez; E. M. Salmoral; K. Traverso; M. E. Floccari

2002-01-01

275

Death of a classified worker probably caused by overexposure to gamma radiation  

Microsoft Academic Search

This paper describes the case of an industrial radiographer who was seriously overexposed to gamma radiation. The exact circumstances of this exposure were not established but it was concluded that he was repeatedly irradiated probably to a total average whole body dose of at least 10 Gy over several years. Also, a much larger dose to a hand required its

D C Lloyd; A A Edwards; E J Fitzsimons; C D Evans; R Railton; P Jeffrey; T G Williams; A D White; M Ikeya; H Sumitomo

1994-01-01

276

Inactivation and stability of viral diagnostic reagents treated by gamma radiation.  

PubMed

The objective of this study was to apply the pertinent findings from gamma inactivation of virus infectivity to the production of high quality diagnostic reagents. A Gammacell 220 (Atomic Energy of Canada, Ltd., Ottawa, Canada) was used to subject 38 viruses grown in either susceptible tissue cultures or embryonated chicken eggs to various doses of gamma radiation from a cobalt-60 source. The radiation required to reduce viral infectivity was 0.42 to 3.7 megarads (Mrad). The effect of gamma treatment on the antigenic reactivity of reagents for the complement fixation (CF), hemagglutination (HA) and neuraminadase assays was determined. Influenza antigens inactivated with 1.7 Mrad displayed comparable potency, sensitivity, specificity and stability to those inactivated by standard procedures with beta-propiolactone (BPL). Significant inactivation of influenza N1 and B neuraminidase occurred with greater than 2.4 Mrad radiation at temperatures above 4 degrees C. All 38 viruses were inactivated, and CF or HA antigens were prepared successfully. Antigenic potency remained stable with all antigens for 3 years and with 83% after 5 years storage. Influenza HA antigens evaluated after 9 years of storage demonstrated 86% stability. Gamma radiation is safer than chemical inactivation procedures and is reliable and effective replacement for BPL in preparing diagnostic reagents. PMID:2126734

White, L A; Freeman, C Y; Hall, H E; Forrester, B D

1990-10-01

277

Molecular weights and molecular weight distributions of irradiated cellulose fibers by gel permeation chromatography. [. gamma. radiation  

Microsoft Academic Search

Radiation degradation of cellulose fibers was investigated by gel permeation chromatography (GPC). Scoured cotton of Mexican variety (cellulose I), Polynosic rayon (cellulose II), and their microcrystalline celluloses obtained by hydrolysis of the original fibers were irradiated by Co-60 ..gamma..-rays under vacuum or humid conditions. The irradiated samples were then nitrated under nondegradative conditions. The molecular weights and molecular weight distributions

Y. Kusama; E. Kageyama; M. Shimada; Y. Nakamura

1976-01-01

278

Gamma scintillation probe for field use and measurements of radiation background in Puget Sound  

Microsoft Academic Search

A probe containing a 5 x 4-in. NaI( TI) crystal was built for field survey work with a small ship and portable counting equipment. The gamma radiation background was mcas- ured to a depth of 80 m at 3 locations in the lower part of Puget Sound. The count rate dccreascd very rapidly and nonlinearly in the first few meters

CHARLES M. PROCTOR; EMANUEL PAPADOPULOS; RALPH H. FIRMINHAC

1962-01-01

279

Principal Component Analysis of Gamma-Ray Spectra for Radiation Portal Monitors  

Microsoft Academic Search

The scanning of cargo for radiological and nuclear material is vital in detecting the illicit trafficking of such materials. The deployment of technologies such as Radiation Portal Monitors (RPMs) has enabled screening for the presence of gamma and neutron emitting radionuclides.

David Boardman; Mark Reinhard; Alison Flynn

2012-01-01

280

THE BEHAVIOR OF EXPLOSIVES UNDER THE IMPACT OF $gamma$RADIATION. PART I  

Microsoft Academic Search

Smokeless powder (nitrocellulose with various gelatinizing and ; plasticizing agents) was exposed to Co⁶° gamma radiation at dosages ; ranging from 0 to 15 x 10⁶ r and pressures from 0 to 300 mm Hg. The ; stability of the powder under varying doses and pressures was examined. The 4 ; samples studied consisted of powders of (a) gelatinized smokeless

E. Piantanida; M. Piazzi

1960-01-01

281

THE EFFECTS OF GAMMA RADIATION ON JPN PROPELLANT. Memorandum Report No. 122  

Microsoft Academic Search

Strips of JPN propellart were subjected to the gamma radiation of cobalt-; 60 sources at Brooknaven National Laboratory. These strips were chemically ; analyzed and physically tested. Significant changes were observed in the ; viscosity of the nitrocellulose, the available centralites and the stability of ; the propellant. The main transformation product of the ethyl centralitc ; stabilizer was 4-nitrocentralite.

A. Owyang; H. Rosenwasser

1956-01-01

282

Can gamma radiation be produced in the electrical environment above thunderstorms?  

Microsoft Academic Search

Calculations indicate that regions above large mesocsale convective systems may be favorable electrical environments for the production of gamma radiation by runaway electrons in bremsstrahlung collisions. It is well known (Gurevich, 1961) that an electric field however small can accelerate an electron continuously until the electric field is larger than the oppposing force of friction. Since the force of friction

Britton Chang; Colin Price

1995-01-01

283

Caffeine sensitization of cultured mammalian cells and human lymphocytes irradiated with gamma rays and fast neutrons: a study of relative biological effectiveness in relation to cellular repair  

Microsoft Academic Search

The sensitizing effects of caffeine were studied in baby hamster kidney (BHK-21) cells and human lymphocytes following irradiation with gamma rays and fast neutrons. Caffeine sensitization occurred only when log-phase BHK cells and mitogen-stimulated lymphocytes were exposed to the two radiations. Noncycling (confluent) cells of BHK resulted in a shouldered survival curve following gamma irradiation while a biphasic curve was

M. A. Hannan; D. P. Gibson

1985-01-01

284

Crosstalk Between alpha\\/betaT Cells and gamma\\/deltaT Cells in vivo: Activation of alpha\\/beta T-Cell Responses after gamma\\/delta T-Cell Modulation with the Monoclonal Antibody GL3  

Microsoft Academic Search

Although gamma\\/delta T cells express numerous in vitro functions similar to alpha\\/beta T cells, little is known about their biological functioning in vivo. Furthermore, it is unclear whether alpha\\/beta T cells and gamma\\/delta T cells act independently or in a coordinated way. In the present study, gamma\\/delta T cells were modulated in vivo by i.p. injection of the anti-gamma\\/delta T-cell

Stefan H. E. Kaufmann; Carmen Blum; Shigeki Yamamoto

1993-01-01

285

Effects of gamma irradiation on the radiation-resistant bacteria and polyphenol oxidase activity in fresh kale juice  

NASA Astrophysics Data System (ADS)

Gamma radiation was performed to prolong the shelf life of natural kale juice. The total aerobic bacteria in fresh kale juice, prepared by a general kitchen process, was detected in the range of 106 cfu/ml, and about 102 cfu/ml of the bacteria survived in the juice in spite of gamma irradiation treatment with a dose of 5 kGy. Two typical radiation-resistant bacteria, Bacillus megaterium and Exiguobacterium acetylicum were isolated and identified from the 5 kGy-irradiated kale juices. The D10 values of the vegetative cell and endospore of the B. megaterium in peptone water were 0.63±0.05 and 1.52±0.05 kGy, respectively. The D10 value of the E. acetylicum was calculated as 0.65±0.06 kGy. In the inoculation test, the growth of the surviving B. megaterium and E. acetylicum in the 3 5 kGy-irradiated kale juice retarded and/or decreased significantly during a 3 d post-irradiation storage period. However, there were no significant differences in the residual polyphenol oxidase activity and browning index between the nonirradiated control and the gamma irradiated kale juice during a post-irradiation period.

Kim, Dongho; Song, Hyunpa; Lim, Sangyong; Yun, Hyejeong; Chung, Jinwoo

2007-07-01

286

DNA damage in hair root cells as a biomarker for gamma ray exposure.  

PubMed

The purpose of the present research is to examine whether human hair root cells can be used for dose assessment after in vitro exposure to ionizing radiation. Hair root samples plucked from random head regions were collected from 5 healthy human subjects. Some of these hair samples were used as control and some were irradiated with 0.5-5Gy of gamma ray using a Cs-137 gamma irradiator at a dose rate of 0.14Gy/s. DNA damage (single-strand breaks) was determined in hair root cells of these samples using the comet assay technique. The comet assay parameters, tail length (TL) and tail moment (TM), showed a significant increase (p<.05) in single-strand DNA breaks in hair roots cells of the exposed samples compared to control. A linear dose-effect relationship was observed when tail moment or tail length was plotted against the log of the radiation dose. This research suggests a possible use of human hair root cell DNA damage as a biomarker especially for low dose radiation. PMID:23811168

Tepe Çam, Semra; Seyhan, Nesrin

2013-06-28

287

Production of hydrogel wound dressings using gamma radiation  

NASA Astrophysics Data System (ADS)

Hydrogel wound dressings have been prepared using the gamma rays irradiation technique. The dressings are composed of poly(vinyl pyrrolidone) (PVP), poly(ethylene glycol) (PEG) and agar. The influence of some process parameters on the properties of the dressings has been investigated as: the gel fraction, maximum swelling, swelling kinetics, and mechanical properties. The gel fraction increases with increasing PVP concentration due to increased crosslink density, and decreases with increasing the PEG concentration. PEG seems to act not only as plasticizer but also to modify the gel properties as gelation% and maximum swelling. The prepared hydrogels dressings could be considered as a good barrier against microbes.

Ajji, Z.; Othman, I.; Rosiak, J. M.

2005-04-01

288

Activation of a c-K-ras oncogene by somatic mutation in mouse lymphomas induced by gamma radiation  

SciTech Connect

Mouse tumors induced by gamma radiation are a useful model system for oncogenesis. DNA from such tumors contains an activated K-ras oncogene that can transform NIH 3T3 cells. This report describes the cloning of a fragment of the mouse K-ras oncogene containing the first exon from both a transformant in rat-2 cells and the brain of the same mouse that developed the tumor. Hybrid constructs containing one of the two pieces were made and only the plasmid including the first exon from the transformant gave rise to foci in NIH 3T3 cells. There was only a single base difference (G----A) in the exonic sequence, which changed glycine to aspartic acid in the transformant. By use of a synthetic oligonucleotide the presence of the mutation was demonstrated in the original tumor, ruling out modifications during DNA-mediated gene transfer and indicating that the alteration was present in the thymic lymphoma but absent from other nonmalignant tissue. The results are compatible with gamma radiation being a source of point mutations.

Guerrero, I.; Villasante, A.; Corces, V.; Pellicer, A.

1984-09-14

289

Response of oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), eggs to gamma radiation  

NASA Astrophysics Data System (ADS)

As insects increase in radiotolerance as they develop and usually several developmental stages of the pest may be present in the fresh shipped commodity, it is important to know the radiation susceptibility of the stages of the target insect before the establishment of ionizing radiation quarantine treatments. This study was performed to determine the radiotolerance of eggs of the oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), to gamma radiation. This species is considered as one of the most serious worldwide pests for temperate fruits, especially peaches. Eggs (12 h old) were exposed to 0 (control), 25, 35, 50, 75, 100, 125 and 150 Gy of gamma radiation. Surviving larvae were allowed to feed on an artificial diet. Three days after irradiation, it was verified that larvae’s cephalic capsules were significantly affected by gamma radiation, and the estimated mean LD90 and LD99 were 66.3 Gy and 125.8 Gy, respectively. Oriental fruit moth eggs revealed to be quite radiosensitive and very low doses as 50 Gy were sufficient to disrupt G. molesta embryogenesis. At 25 Gy, only male adults originated from the surviving larvae and, after mating with untreated fertile females, shown to be sterile.

Silva, W. D.; Arthur, V.; Mastrangelo, T.

2010-10-01

290

Solid state polymerization of acrylamide initiated by gamma radiation  

Microsoft Academic Search

The solid-state polymerization of acrylamide, both in a radiation field ; and after removal from the field, is shown to proceed by an unusual kinetic ; mechanism. The usual steady state assumption is found to be inadequate because ; there seems to be no free radical termination (in the normal sense) involved. ; These results are consistent with the view

B. Baysal; G. Adler; D. Ballantine; P. Colombo

1960-01-01

291

Gamma radiation sensitivity of foodborne pathogens on meat and poultry  

SciTech Connect

Several factors have been identified that may affect the responses of foodborne pathogens to ionizing radiation. Among these are the temperature and atmosphere during the process of irradiation; the medium in which the pathogen is suspended; and the genus, species, serovar, and physiological state of the organism. In addition to these factors, variations in {open_quotes}apparent{close_quotes} radiation sensitivity of bacteria may occur because of the incubation conditions and media used to estimate the number of surviving colony-forming units. Both incubation temperature and culture media frequently affect the ability of injured bacteria to recover. Because there are so many possible variables, it is often difficult to compare data on the radiation sensitivity of foodborne pathogens from different studies. The objectives of the studies reported here were to compare the radiation sensitivities of Bacillus cereus on beef, beef gravy, chicken, pork, and turkey; and of Escherichia coli 0157:H7, Listeria monocytogenes, Salmonella, and Staphylococcus aureus on beef, pork, lamb, turkey breast, and turkey leg meats. Examples of the effects of serovar, irradiation temperature, growth phase, and atmosphere during irradiation were also examined.

Thayer, D.W.; Boyd, G. [USDA, Philadelphia, PA (United States)

1994-12-31

292

Inactivation of foodborne pathogens on seafood by gamma radiation  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ionizing radiation is used on a global basis to improve the phytosanitary and microbial safety and shelf-life of foods. In recent years progress has been made in the commercial application of irradiation to sterilize destructive invasive insects and to irradiate produce to improve its microbiologica...

293

Mutational spectrum analysis of umuC-independent and umuC-dependent gamma-radiation mutagenesis in Escherichia coli.  

PubMed

gamma-Radiation mutagenesis (oxic versus anoxic) was examined in wild-type, umuC and recA strains of Escherichia coli K-12. Mutagenesis [argE3(Oc)----Arg+] was blocked in a delta (recA-srlR)306 strain at the same doses that induced mutations in umuC122::Tn5 and wild-type strains, indicating that both umuC-independent and umuC-dependent mechanisms function within recA-dependent misrepair. Analyses of various suppressor and back mutations that result in argE3 and hisG4 ochre reversion and an analysis of trpE9777 (+1 frameshift) reversion were performed on umuC and wild-type cells irradiated in the presence and absence of oxygen. While the umuC strain showed the gamma-radiation induction of base substitution and frameshifts when irradiated in the absence of oxygen, the umuC mutation blocked all oxygen-dependent base-substitution mutagenesis, but not all oxygen-dependent frameshift mutagenesis. For anoxically irradiated cells, the yields of GC----AT [i.e., at the supB and supE (Oc) loci] and AT----GC transitions (i.e., at the argE3 and hisG4 loci) were essentially umuC independent, while the yields of (AT or GC)----TA transversions (i.e., at the supC, supL, supM, supN and supX loci) were heavily umuC dependent. These data suggest new concepts about the nature of the DNA lesions and the mutagenic mechanisms that lead to gamma-radiation mutagenesis. PMID:2538729

Sargentini, N J; Smith, K C

1989-04-01

294

Evaluation of phenolic compounds in maté (Ilex paraguariensis) processed by gamma radiation  

NASA Astrophysics Data System (ADS)

The radiation food processing has been demonstrating great effectiveness in the attack of pathogenic agents, while little compromising nutritional value and sensorial properties of foods. The maté (Ilex paraguariensis), widely consumed product in South America, generally in the form of infusions with hot or cold water, calls of chimarrão or tererê, it is cited in literature as one of the best sources phenolic compounds. The antioxidants action of these constituent has been related to the protection of the organism against the free radicals, generated in alive, currently responsible for the sprouting of some degenerative illness as cancer, arteriosclerosis, rheumatic arthritis and cardiovascular clutters among others. The objective of that work was to evaluate the action of the processing for gamma radiation in phenolic compounds of tererê beverage in the doses of 0, 3, 5, 7 and 10 kGy. The observed results do not demonstrate significant alterations in phenolic compounds of tererê beverage processed by gamma radiation.

Furgeri, C.; Nunes, T. C. F.; Fanaro, G. B.; Souza, M. F. F.; Bastos, D. H. M.; Villavicencio, A. L. C. H.

2009-07-01

295

Repair of gamma-ray-induced base damage in L5178Y sublines is damage type-dependent and unrelated to radiation sensitivity.  

PubMed

The L5178Y (LY) murine lymphoma sublines LY-R and LY-S are differentially sensitive to ionizing radiation. The high radiation sensitivity of LY-S cells is related to impaired rejoining of DNA double strand breaks. We found previously that the gamma-ray-induced base damage is higher in the more radiosensitive LY-S subline. Here, we examine the role of the repair of ionizing radiation induced base damage in relation to the radiosensitivity difference of these sublines. We used the GS/MS technique to estimate the repair rates of six types of base damage in gamma-irradiated LY cells. All modified DNA bases identified in the course of this study were typical for irradiated chromatin. The total amount of initial base damage was higher in the radiation sensitive LY-S subline than in the radiation resistant LY-R subline. The repair rates of 5-OHMeUra, 5-OHCyt, 8-OHAde were similar in both cell lines, the repair rates of FapyAde and 8-OHGua were higher in the radiosensitive LY-S cell line, whereas the repair of 5-OHUra was faster in its radioresistant counter, the LY-R. Altogether, the repair rates of the y-ray-induced DNA base damage in LY sublines are related neither to the initial amounts of the damaged bases nor to the differential lethal or mutagenic effects of ionizing radiation in these sublines. PMID:11732621

Kruszewski, M; Zastawny, T H; Szumiel, I

2001-01-01

296

Differential radiation response of cultured endothelial cells and smooth myocytes  

SciTech Connect

In vivo observations have suggested that endothelial cells are the most radiosensitive elements of the vascular wall. To test whether this represents an intrinsic differential sensitivity, the response of bovine aortic endothelial cells and smooth myocytes was investigated in confluent cell cultures exposed to single doses of gamma radiation (250, 500, 1,000 or 2,000 rad). Both cell types showed a dose-dependent decrease in attachment efficiency when dissociated and replated at six hours after radiation. However, the attachment efficiency in both cell types was similar when a 72-hour postirradiation incubation period was used prior to dissociation of the cells. Growth inhibition was significantly greater (7- to 10-fold) in endothelial cells than in myocytes when examined four days after attachment. Confluent endothelial monolayers showed a dose-dependent, progressive cell loss during the 72-hour postirradiation period (70% after 1,000 rad); the myocyte cultures showed no radiation effect on the cell numbers. In spite of the reduction in number, the endothelial cells maintained the continuity of their monolayer by compensation with an increase in mean cell size. Endothelial cells developed multiple structural lesions, including an increase in the number and size of residual and lysosomal bodies, electron-lucent cytoplasmic defects, interruptions in the plasma membrane and irregular aggregation of chromatin, causing electron-lucent nuclei. These changes increased in severity with time and dose and were most pronounced 24 to 72 hours after 1,000 rad. No significant ultrastructural alterations were detected in myocytes four days after 2,000 rad.

Johnson, L.K.; Longenecker, J.P.; Fajardo, L.F.

1982-09-01

297

High-total-dose gamma and neutron radiation tolerance of VCSEL assemblies  

NASA Astrophysics Data System (ADS)

Optical fiber technology is seriously considered for communication and monitoring applications during the operation and maintenance of future thermonuclear fusion reactors. Their environment is characterized, in particular, by possibly high gamma dose-rates and total doses in excess of 10 MGy. In addition, the maintenance equipment might be stored in close vicinity of the reactor during its operation and therefore the communication devices might also be exposed to a substantial neutron fluence. The feasibility of applying photonic technology in these radiation fields therefore needs to be assessed. Whereas many reports deal with the radiation behavior of a variety of fiber-optic devices, only little information is available on the radiation tolerance at high total dose (e.g. > 1 MGy). We describe our recent results obtained on vertical-cavity surface-emitting laser (VCSEL) assemblies. We have conducted high total dose (up to 20 MGy) irradiation experiments on such devices, which confirmed their excellent gamma radiation hardness. The optical power loss at nominal forward current was less than 2 dB and the threshold current remained unaltered. We have also irradiated these devices with neutrons inside the BR1 reactor (SCK•CEN, Mol, Belgium) up to a total fluence on the order of 1015 n×cm-2. The response of VCSELs to neutrons is, as expected, different from that to gamma radiation. VCSELs previously exposed to gamma rays exhibited an accelerated degradation under neutron radiation compared to not pre-irradiated devices. The beneficial effect of applying a continuous forward bias to the VCSELs is also evidenced.

Berghmans, Francis; Van Uffelen, Marco; Decréton, Marc C.

2002-09-01

298

A practical method for measuring angular distribution of radiation from multiple gamma sources  

SciTech Connect

Radiation survey data are a necessary prerequisite for planning D and D activities at a nuclear facility. For an individual room with a small number of high level radiation sources whose locations are known a priori, the survey process, shielding calculations, and work planning process are straightforward. However, when the space is large and complex, or when an accident has left process equipment and the space in disarray, gathering survey data while minimizing dose to the surveyor may require specialized equipment and analytical methods. The Object Shelter (OS) that encloses the destroyed Unit 4 at the Chernobyl Nuclear Power Plant (ChNPP) contains many intensive radiation sources such as fuel containing material (solidified melted fuel, fragment spent fuel, and fragmented fresh fuel), destroyed/contaminated piping and mechanical equipment, and contaminated dust and debris from accident recovery. These high intensity radiation sources are scattered throughout the facility in unknown configurations, so it is essential to know the angular distribution of gamma radiation in order to plan work and to design shielding. As previously reported, a prototype tool for measuring angular distribution of gamma radiation was developed, constructed and tested at ChNPP OS. The prototype device, designated ShD-1, consisted primarily of a lead (Pb) sphere containing recessed thermoluminescent detectors (TLDs). ShD-1 was successfully used to collect radiation survey data for planning the largest construction project yet performed at ChNPP OS, the stabilization project. From this application we gained insight into some limitations of the prototype design and report here advancements in the design. The multidetector device for measurement of angular distributions of intensity of gamma - radiation is described. Results of tests of experimental model of device are presented and prospects of use of such device are shown. (authors)

Batiy, V.; Pravdivyj, O.; Stoyanov, O. [Institute for Safety Problems of Nuclear Power Plants, National Academy of Sciences of Ukraine (Ukraine); Kochnev, N.; Selukova, V. [National Science Center -Kharkiv Institute of Physics and Technology (Ukraine); Schmieman, E. [Battelle Memorial Institute (United States)

2007-07-01

299

Tissue distribution of human gamma delta T cells: no evidence for general epithelial tropism  

Microsoft Academic Search

In man and mice only a small proportion of T cells in the peripheral lymphoid compartment express the gamma delta T cell receptor (TCR). In mice, however, gamma delta T cells comprise the predominant population at particular epithelial sites--in epidermis and epithelia of intestine, reproductive organs, and tongue. The distribution of gamma delta T cells in normal human tissues was

T M Vroom; G Scholte; F Ossendorp; J Borst

1991-01-01

300

Effects of Ionizing Radiation in Nonirradiated Cells  

SciTech Connect

Implicit in understanding the biological effects of ionizing radiation and subsequent risks associated with such exposure is that only cells ?hit? by the radiation are likely to carry the legacy of radiation damage. When a cell is ?hit? the deposition of energy can result in direct damage to the genetic material or indirect damage to critical nuclear targets through the radiolysis of water (Figure 1). The subsequent action of DNA repair processes either removes the lesion(s), or fixes the induced damage such that all surviving progeny of an irradiated cell carry the burden of radiation exposure, e.g., a gene mutation and/or a chromosomal rearrangement (Figure 1A). This central tenet in our understanding of the biological effects of ionizing radiation has now been called into question by the description of a number of non-targeted effects associated with radiation exposure. These effects can occur in the progeny of irradiated cells generations after the initial exposure, and/or in cells that were not directly traversed by ionizing radiation, but were some distance from the ?hit? cells (reviewed in 1, 2) (Figure 1B). The work of Belyakov and colleagues in this issue of PNAS demonstrates for the first time non-targeted bystander responses in a three-dimensional human tissue model system (3). The investigators use a microbeam to deliver defined numbers of charged particles, in this case alpha particles--the type of radiation associated with radon decay, with high accuracy to precise locations (4, 5). A defined area of cells was irradiated in a thin vertical plane, {approx}two cell diameters, to bisect the tissue sample. Because of the inherent nature of the alpha particles there is very little radiation scatter. Consequently cells more than a few microns away from the plane of irradiated cells receive zero radiation dose. At 72 hours post irradiation, the tissues were formalin fixed, paraffin embedded, and sectioned in strips at increasing distances parallel to the plane of irradiated cells. This allowed analysis of tissue slices containing only non-irradiated cells at known distances from the plane of irradiated cells. Unirradiated cells up to 1 mm away from the irradiated cells, {approx}50-75 cell diameters distant, showed a significant enhancement in the measured fractions of apoptotic and micronucleated cells.

Morgan, William F.; Sowa, Marianne B.

2005-10-04

301

Radiation Enhances Regulatory T Cell Representation  

SciTech Connect

Purpose: Immunotherapy could be a useful adjunct to standard cytotoxic therapies such as radiation in patients with micrometastatic disease, although successful integration of immunotherapy into treatment protocols will require further understanding of how standard therapies affect the generation of antitumor immune responses. This study was undertaken to evaluate the impact of radiation therapy (RT) on immunosuppressive T regulatory (Treg) cells. Methods and Materials: Treg cells were identified as a CD4{sup +}CD25{sup hi}Foxp3{sup +} lymphocyte subset, and their fate was followed in a murine TRAMP C1 model of prostate cancer in mice with and without RT. Results: CD4{sup +}CD25{sup hi}Foxp3{sup +} Treg cells increased in immune organs after local leg or whole-body radiation. A large part, but not all, of this increase after leg-only irradiation could be ascribed to radiation scatter and Treg cells being intrinsically more radiation resistant than other lymphocyte subpopulations, resulting in their selection. Their functional activity on a per-cell basis was not affected by radiation exposure. Similar findings were made with mice receiving local RT to murine prostate tumors growing in the leg. The importance of the Treg cell population in the response to RT was shown by systemic elimination of Treg cells, which greatly enhanced radiation-induced tumor regression. Conclusions: We conclude that Treg cells are more resistant to radiation than other lymphocytes, resulting in their preferential increase. Treg cells may form an important homeostatic mechanism for tissues injured by radiation, and in a tumor context, they may assist in immune evasion during therapy. Targeting this population may allow enhancement of radiotherapeutic benefit through immune modulation.

Kachikwu, Evelyn L.; Iwamoto, Keisuke S.; Liao, Yu-Pei; DeMarco, John J.; Agazaryan, Nzhde [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA (United States); Economou, James S. [Department of Surgical Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA (United States); McBride, William H. [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA (United States); Schaue, Doerthe, E-mail: dschaue@mednet.ucla.edu [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA (United States)

2011-11-15

302

Surface heterogeneity of tumor cells and changes upon ionizing radiation  

SciTech Connect

Heterogeneous distribution of surface domains is a characteristic feature of the tumor cell surface and the distribution differs from that of normal cells. During the malignant transformation the heterogeneity may change or disappear. Cell lines with various metastasizing capacities show different distributions of membrane domains or other differences in membrane or surface organization. We have demonstrated that the amount and distribution of negatively charged sites of B 16 melanoma membranes changed upon ionizing radiation (X-ray, {sup 60}Co-gamma). In the case of the P 388 lymphoma, however, only the amount of negatively charged sites change after irradiation, the distribution remains unaltered. Both features proved to be radioresistant in human lymphoid leukemic cells. 93 references.

Somosy, Z.; Csuka, O.; Kubasova, T.; Kovacs, J.; Koeteles, G.J. (Frederic Joliot-Curie National Research Institute for Radiobiology and Radiohygiene, Budapest (Hungary))

1989-09-01

303

Modern Methods of Real-Time Gamma Radiation Monitoring for General Personal Protection  

NASA Astrophysics Data System (ADS)

Real-time radiation detectors become an essential part of emergency personnel who may have to respond to unknown accidents, incidents or terrorist attacks, which could involve radioactive material. More and more ordinary citizens are interested in personal radiation protection as well. Reasons include lost sources, nuclear industrial accidents, nuclear or radiological terrorism and the possibility of nuclear weapons being used in a war. People want to have the ability to measure it for themselves and they want to be notified when the radiation levels are increased. To meet this demand, considerable research into new sensors is underway, including efforts to enhance the sensor performance through both the material properties and manufacturing technologies. Deep understanding of physical properties of the materials under the influence of radiation exposure is vital for the effective design of dosimeter devices. Detection of radiation is based on the fact that both the electrical and the optical properties of the materials undergo changes upon the exposure to ionizing radiation. It is believed that radiation causes structural defects. The influence of radiation depends on both the dose and the parameters of the films including their thickness: the degradation is more severe for the higher dose and the thinner films. This paper presents overview of modern methods of real-time gamma radiation monitoring for personal protection of radiation workers and general public and suggests further developments in this area.

Korostynska, O.; Arshak, K.; Arshak, A.; Vaseashta, Ashok

304

Sublethal effects in Atlantic salmon (Salmo salar) exposed to mixtures of copper, aluminium and gamma radiation.  

PubMed

The present study was designed to investigate the effects in presmolt of Atlantic salmon (Salmo salar) exposed to copper (Cu), aluminium (Al) and gamma radiation, individually or in combination. Fish were exposed for 48 h to metals added to lake water; 10, 40 and 80 ?g Cu/L, 250 ?g Al/L and a combination of 40 ?g Cu/L and 250 ?g Al/L. In addition, gamma radiation (4-70 mGy delivered over 48 h) was added as an additional exposure stressor. Selected endpoints were chosen to reveal different toxic mechanisms and included Cu and Al accumulation on gills, blood chemistry and haematological variables (plasma sodium and chloride, haematocrit, glucose), hepatic levels of reduced and oxidised glutathione (GSH and GSSG) and hepatic transcriptional response of glutathione peroxidase (GPx), gamma-glutamylcysteine synthetase (GCS), metallothionein (MT) and ubiquitin. Exposure to Cu alone resulted in gill accumulation of Cu, reduction of plasma ions and increased transcriptional response of GPx, MT and ubiquitin. Exposure to Al alone reduced plasma ion levels but did not affect any of the hepatic biomarkers except for ubiquitin. The combined metal exposure (Cu + Al) altered the GSH levels, however GPx and MT were not affected suggesting a different mode of detoxification in the combined exposure. Gamma radiation appeared to influence GSH and ubiquitin levels. The observed effects seemed to be both stressor and concentration dependent. PMID:22583837

Heier, Lene Sørlie; Teien, Hans Christian; Oughton, Deborah; Tollefsen, Knut-Erik; Olsvik, Pål A; Rosseland, Bjørn Olav; Lind, Ole Christian; Farmen, Eivind; Skipperud, Lindis; Salbu, Brit

2012-05-13

305

Evaluation of fungal burden and aflatoxin presence in packed medicinal plants treated by gamma radiation.  

PubMed

This study was developed to evaluate the fungal burden, toxigenic molds, and mycotoxin contamination and to verify the effects of gamma radiation in four kinds of medicinal plants stored before and after 30 days of irradiation treatment. Eighty samples of medicinal plants (Peumus boldus, Camellia sinensis, Maytenus ilicifolia, and Cassia angustifolia) purchased from drugstores, wholesale, and open-air markets in São Paulo city, Brazil, were analyzed. The samples were treated using a (60)Co gamma ray source (Gammacell) with doses of 5 and 10 kGy. Nonirradiated samples were used as controls of fungal isolates. For enumeration of fungi on medicinal plants, serial dilutions of the samples were plated in duplicate onto dichloran 18% glycerol agar. The control samples revealed a high burden of molds, including toxigenic fungi. The process of gamma radiation was effective in reducing the number of CFU per gram in all irradiated samples of medicinal plants after 30 days of storage, using a dose of 10 kGy and maintaining samples in a protective package. No aflatoxins were detected. Gamma radiation treatment can be used as an effective method for preventing fungal deterioration of medicinal plants subject to long-term storage. PMID:20501045

Aquino, Simone; Gonçalez, Edlayne; Rossi, Maria Helena; Nogueira, Juliana Hellmeister de Campos; Reis, Tatiana Alves Dos; Corrêa, Benedito

2010-05-01

306

Development of Detectors for Measurement of Neutron and Gamma-radiation from Laser-Produced Plasma  

NASA Astrophysics Data System (ADS)

The paper describes the development of the detectors widely used in the nuclear physics for measurement of neutron and gamma-radiation in laser-produced plasma. Under investigation is plasmas generated by action on solid-state target by radiation from picosecond terawatt Nd-glass laser having intensity of 10 to the power 16 10 to the power 18 Watt per centimeter squared. Peculiarities of such plasmas have called for modernization of conventional methods and detectors for measurement of neutron and gamma-radiation. Diagnostic methods imply use of scintillation counters based on stilbene crystal, scintillation gamma-spectrometer based on NaI(Tl) crystal and proportional counters based on He III. The paper as well presents results of the experimental investigation on generation of gamma-quanta and neutrons in laser-produced plasma. The experimental methods and detectors described in the paper provide a basis for studies on a wide spectrum of atomic and nuclear processes going in the laser-produced dense plasmas. The present work was supported by International Science and Technology Center under Project number 856.

Matafonov, Anatoly

2000-03-01

307

(Gamma scattering in condensed matter with high intensity Moessbauer radiation)  

SciTech Connect

There are four areas where major progress has occurred this year. We have applied the Fourier-transform method of describing and analyzing Moessbauer effect (ME) line shapes to make measurements of the temperature dependence of the recoilless fraction in tungsten. We have carried out quasi-elastic measurements of the gamma scattering from viscous liquids, learning about diffusive motion in polydimethylsiloxane, pentadecane, and glycerol. We have made major progress in fundamental physics, having shown for the first time how to determine precise quantum interference parameters, obtaining experimental results on the 46.5 keV line of {sup 183}W and the 129 keV line of {sup 191}Ir. Finally, we have continued our development of MICE detectors, with a theoretical analysis of the MICE lineshape and its relation to the lineshape of conventional transmission ME spectroscopy. 12 refs.

Not Available

1989-01-01

308

Natural gamma-ray spectrometry as a tool for radiation dose and radon hazard modelling.  

PubMed

We reviewed the calibration procedures of gamma-ray spectrometry with particular emphasis to factors that affect accuracy, detection limits and background radiation in field measurements for dosimetric and radon potential mapping. Gamma-ray spectra were acquired in western Liguria (Italy). The energy windows investigated are centred on the photopeaks of (214)Bi (1.76 MeV), (208)Tl (2.62 MeV) and (40)K (1.46 MeV). The inferred absorbed dose rate and the radon flux are estimated to be lower than 60 nGy h(-1) and 22 Bq m(-2)h(-1), respectively. PMID:19249218

Verdoya, M; Chiozzi, P; De Felice, P; Pasquale, V; Bochiolo, M; Genovesi, I

2009-01-24

309

Dose quantities and instrumentation for measuring environmental gamma radiation during emergencies  

SciTech Connect

The dosimetry for exposure to gamma radiation in the environment is reviewed, including the factors used to convert measurements of traceable quantities to effective dose equivalent. A value of 0.70 Sv Gy-1 is widely used to convert air kerma or absorbed dose-to-air to effective dose equivalent, but recent work shows that a value of 0.86 Sv Gy-1 is more appropriate for deposited radionuclides. The arguments are reviewed and the implications of using operational dose equivalent quantities defined by the International Commission on Radiation Units and Measurements are considered. For planar deposited sources in the environment, it is shown that the use of ambient dose equivalent quantities without applying conversion factors, could significantly overestimate effective dose equivalent. In contrast, the adoption of the new effective dose quantity defined by the International Commission on Radiological Protection in Publication 60 will have a small impact on conversion factors for gamma radiation in the environment. Practical aspects of measurement are also considered, and five instruments suitable for measuring environmental gamma radiation have been evaluated in the laboratory and in field tests. The instruments include models with scintillation detectors, a Geiger-Mueller detector, and a high-pressure ionization chamber, the choice being influenced by those commonly used in European Community countries for routine and emergency monitoring. The main disadvantage of all the instruments is the lack of spectral information, so a straightforward emergency instrument capable of discriminating between natural and artificial radionuclides has also been evaluated.

Clark, M.J.; Burgess, P.H.; McClure, D.R. (National Radiological Protection Board, Oxfordshire (United Kingdom))

1993-05-01

310

Dose quantities and instrumentation for measuring environmental gamma radiation during emergencies.  

PubMed

The dosimetry for exposure to gamma radiation in the environment is reviewed, including the factors used to convert measurements of traceable quantities to effective dose equivalent. A value of 0.70 Sv Gy-1 is widely used to convert air kerma or absorbed dose-to-air to effective dose equivalent, but recent work shows that a value of 0.86 Sv Gy-1 is more appropriate for deposited radionuclides. The arguments are reviewed and the implications of using operational dose equivalent quantities defined by the International Commission on Radiation Units and Measurements are considered. For planar deposited sources in the environment, it is shown that the use of ambient dose equivalent quantities without applying conversion factors, could significantly overestimate effective dose equivalent. In contrast, the adoption of the new effective dose quantity defined by the International Commission on Radiological Protection in Publication 60 will have a small impact on conversion factors for gamma radiation in the environment. Practical aspects of measurement are also considered, and five instruments suitable for measuring environmental gamma radiation have been evaluated in the laboratory and in field tests. The instruments include models with scintillation detectors, a Geiger-Müller detector, and a high-pressure ionization chamber, the choice being influenced by those commonly used in European Community countries for routine and emergency monitoring. The main disadvantage of all the instruments is the lack of spectral information, so a straightforward emergency instrument capable of discriminating between natural and artificial radionuclides has also been evaluated. PMID:8491600

Clark, M J; Burgess, P H; McClure, D R

1993-05-01

311

High-efficiency scintillation detector for combined detection of thermal and fast neutrons and gamma radiation  

DOEpatents

A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation event count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.

Chiles, M.M.; Mihalczo, J.T.; Blakeman, E.D.

1987-02-27

312

High-efficiency scintillation detector for combined of thermal and fast neutrons and gamma radiation  

DOEpatents

A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation even count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.

Chiles, Marion M. (Knoxville, TN); Mihalczo, John T. (Oak Ridge, TN); Blakeman, Edward D. (Oak Ridge, TN)

1989-01-01

313

Role of l- carnitine in the prevention of seminiferous tubules damage induced by gamma radiation: a light and electron microscopic study  

Microsoft Academic Search

The present study, we hypothesized that l-carnitine can minimize germ-cell depletion and morphological features of late cell damage in the rat testis following gamma\\u000a (?)-irradiation. Wistar albino male rats were divided into three groups. Control group received physiological saline 0.2 ml\\u000a intraperitoneally (i.p.), as placebo. Radiation group received scrotal ?-irradiation of 10 Gy as a single dose plus physiological\\u000a saline. Radiation + l-carnitine group

Yeter Topcu-Tarladacalisir; Mehmet Kanter; Mustafa Cem Uzal

2009-01-01

314

Cancer Stem Cells in Radiation Resistance  

Microsoft Academic Search

Highly tumorigenic subpopulations of several solid cancers share characteristics with somatic stem cells. We showed recently that cancer stem cells, or tumor-initiating cells, derived from human glioblastoma surgical specimens and xenografts display resistance to radiation due to increased activation of the DNA damage checkpoint. We additionally showed that these same tumor subpopulations promote tumor angiogenesis through increased expression of vascular

Jeremy N. Rich

2007-01-01

315

Gamma-Ray-Driven Photovoltaic Cells via a Scintillator Interface  

Microsoft Academic Search

A new theoretical model of gamma ray photovoltaic cells is presented with calculations of efficiency ?, open circuit voltage V?, and maximum output power P0max. The model incorporates a scintillator interfaced between the high-energy nuclear isomer and the semiconductor materials of the photovoltaic cell. High-energy ?-photons, E?1 = 1:333 MeV and E?2 = 1:173 MeV, emanate from nuclear isomers Nickel-60m1\\/m2

John K. LIAKOS

2011-01-01

316

Zener diodes for gamma-ray radiation dosimetry  

SciTech Connect

The fundamental properties of Zener diodes and junction field-effect transistors have been studied to use them as a relative dose monitor or a radiation-damage monitor. The response observed at liquid nitrogen temperature, i.e., radiation-induced change in the breakdown voltage of the Zener diode, or change in the breakdown voltage of the pn junction between the gate and the channel (or between the substrate gate and the channel) of the junction field-effect transistor as a function of dose, has shown good linearity. The diode of Toshiba 05Z18 has been found to be useful for doses between 1 and 100 MGy with the fading of response less than 10% for 100 h after irradiation. On the other hand, the junction field-effect transistors of Mitsubishi 2SK33 has proved useful in the region between 0.1 and 10 MGy with the build-up of responses less than 5% for 100 h. The response of both the junction field-effect transistor and the Zener diode has shown a reproducibility within {+-}5. For fast readout, a simple system consisting essentially of a constant-current source together with a digital voltmeter has been constructed. For practical application, the devices from which soldered leads are taken off can be used simply to measure relative doses in various materials.

Nakamura, Shigeki; Okamoto, Shinichi [Univ. of Osaka Prefecture, Sakai (Japan). Research Institute for Advanced Science and Technology

1995-04-01

317

Mitotic Delay induced by Gamma Radiation in Broad Bean Root Meristems  

Microsoft Academic Search

IN attempting to interpret quantitative data on the yield of structural changes induced in chromosomes by radiation, the difficulty arises with material containing cells in random stages of development, as in root tips, that a given dose of radiation delays the arrival of cells at metaphase to an unknown extent. There is thus an uncertainty as to the developmental stage

G. J. Neary; H. J. Evans; S. M. Tonkinson

1957-01-01

318

Comparison of Two Different Techniques on the Human Lymphocytes Morphology and Sensitivity to gamma Radiation.  

National Technical Information Service (NTIS)

The lymphocytes in the peripheral blood are divided into two main subclasses: T cells and B cells. These differ from each other in function and in their sensitivity to radiation. The effort to study which group is more sensitive to radiation has resulted ...

R. Kol

1985-01-01

319

Search for ultra-high-energy radiation from {gamma}-ray bursts  

SciTech Connect

Using data from the CYGNUS extensive air shower array, we have searched for evidence of emission of ultra-high-energy radiation coincident with {gamma}-ray bursts observed by the BATSE instrument on the Compton Gamma-Ray Observatory. No statistically significant excess was found for any point in the sky within 4{sigma} of BATSE`s best location coordinates for any of the 56 bursts examined. Furthermore, no events were seen in the 2.2{degree} radius circular bin surrounding {gamma}-ray burst GRB 920720, whose location was determined accurately by the Compton/Ulysses/PVO Interplanetary Network of satellites. Flux upper limits depend greatly on the actual zenith angle of the burst. Typical fluence upper limits above 100 TeV are {approximately}10{sup {minus}6} erg cm{sup {minus}2}. The fluence upper limits for GRB 920720 is 2 {times} 10{sup {minus}6} erg cm{sup {minus}2}.

Schnee, R.W.; The CYGNUS Collaboration

1993-05-01

320

Search for ultra-high-energy radiation from [gamma]-ray bursts  

SciTech Connect

Using data from the CYGNUS extensive air shower array, we have searched for evidence of emission of ultra-high-energy radiation coincident with [gamma]-ray bursts observed by the BATSE instrument on the Compton Gamma-Ray Observatory. No statistically significant excess was found for any point in the sky within 4[sigma] of BATSE's best location coordinates for any of the 56 bursts examined. Furthermore, no events were seen in the 2.2[degree] radius circular bin surrounding [gamma]-ray burst GRB 920720, whose location was determined accurately by the Compton/Ulysses/PVO Interplanetary Network of satellites. Flux upper limits depend greatly on the actual zenith angle of the burst. Typical fluence upper limits above 100 TeV are [approximately]10[sup [minus]6] erg cm[sup [minus]2]. The fluence upper limits for GRB 920720 is 2 [times] 10[sup [minus]6] erg cm[sup [minus]2].

Schnee, R.W.

1993-01-01

321

Search for Ultra-High-Energy Radiation from gamma -ray Bursts  

NASA Astrophysics Data System (ADS)

Using data from the CYGNUS extensive air shower array, we have searched for evidence of emission of ultra-high-energy radiation coincident with gamma -ray bursts observed by the BATSE instrument on the Compton Gamma-Ray Observatory. No statistically significant excess was found for any point in the sky within 4sigma of BATSE's best location coordinates for any of the 56 bursts examined. Furthermore, no events were seen in the 1.5(deg) radius circular bin surrounding gamma -ray burst GRB 920720, whose location was determined accurately by the Compton/Ulysses/PVO Interplanetary Network of satellites. Flux upper limits depend greatly on the actual zenith angle of the burst. Typical fluence upper limits above 100 TeV are ~ 10(-6) erg cm(-2) . The fluence upper limit for GRB 920720 is 2 times 10(-6) erg cm(-2) .

Williams, D. A.; Cavalli-Sforza, M.; Coyne, D.; Dorfan, D.; Kelley, L.; Klein, S.; Schnee, R.; Yang, T.; Biller, S.; Chumney, P.; Harmon, M.; Shoup, A.; Yodh, G. B.; Alexandreas, D. E.; Allen, G. E.; Chang, C. Y.; Chen, M. L.; Dion, C.; Goodman, J. A.; Haines, T. J.; Stark, M. J.; Dion, G. M.; Berley, D.; Burman, R. L.; Hoffman, C. M.; Nagle, D. E.; Schmidt, D. M.; Sinnis, C.; Weeks, D. D.; Zhang, W. P.; Ellsworth, R. W.; Wu, J.-P.

1993-05-01

322

Gamma radiation effects on phenolics, antioxidants activity and in vitro digestion of pistachio (Pistachia vera) hull  

NASA Astrophysics Data System (ADS)

The effect of gamma radiation (10, 20, 30, 40, 50 and 60 kGy) on tannin, total phenolics, antioxidants activity and in vitro digestion of pistachio hulls has been investigated in this study. The possibility of using the radial diffusion method based on software measurement of the rings area has also been investigated in this study. The software based method in radial diffusion method showed a higher r2 (0.995) value when compared to the traditional method. Irradiation reduced the tannin content (P<0.01) and activity of antioxidants (P<0.05) of pistachio hull extracts but increased the total phenolic content (P<0.05). There was no effect of gamma irradiation on the in vitro digestion of the pistachio hull. Irradiation decreased the digestion rate of the pistachio hull at the dose of 40 kGy when compared to the control. This study showed that gamma irradiation decreased tannin and antioxidants activity of pistachio hull.

Behgar, M.; Ghasemi, S.; Naserian, A.; Borzoie, A.; Fatollahi, H.

2011-09-01

323

Performance of neutron and gamma personnel dosimetry in mixed radiation fields  

SciTech Connect

From 1974 to 1980, six personnel dosimetry intercomparison studies (PDIS) were conducted at the Oak Ridge National Laboratory (ORNL) to evaluate the performance of personnel dosimeters in a variety of neutron and gamma fields produced by operating the Health Physics Research Reactor (HPRR) in the steady state mode with and without spectral modifying shields. A total of 58 different organizations participated in these studies which produced approximately 2000 measurements of neutron and gamma dose equivalents on anthropomorphic phantoms for five different reactor spectra. Based on these data, the relative performance of three basic types of neutron dosimeters (nuclear emulsion film, thermoluminescent (TLD), and track-etch) and two basic types of gamma dosimeters (film and TLD) in mixed radiation fields was assessed.

Swaja, R.E.; Sims, C.S.

1981-01-01

324

Factors affecting the gamma response of TLD-700 chips in mixed-radiation fields  

SciTech Connect

To determine the causes of gamma dose equivalent overestimates observed during mixed-radiation field personnel dosimetry intercomparisons at Oak Ridge National Laboratory, a study was performed to evaluate the effects of phosphor neutron sensitivity, badge materials, and phantoms on the response of TLD-700 chips. The results of the study presented in this paper indicate that even if a phosphor with relatively low neutron sensitivity is used, significant gamma overestimates can occur in mixed fields due to the interaction of the phosphor and badge materials with neutrons. Low energy photons can also contribute to gamma dose equivalent overestimates due to the increased sensitivity of the TLD-700 phosphor to photons with energies below about 100 keV.

Swaja, R.E. (Health and Safety Research Div., Oak Ridge National Lab., Oak Ridge, TN (US)); Scofield, P.A. (Radiological and Occupational Health Dept., Univ. of Michigan, Ann Arbor, MI (US))

1986-10-01

325

Gamma delta T cells in rhesus monkeys and their response to simian immunodeficiency virus (SIV) infection.  

PubMed Central

Recent reports of the increase in peripheral blood gamma delta T cells in HIV+ patients prompted us to examine the gamma delta T cell system in rhesus monkeys (Macaca mulatta) and the responses of these cells to SIV infection. Our results reveal differences in the gamma delta T cell subset composition and their expression of CD8 in the peripheral blood of monkeys and humans. The outgrowth of simian gamma delta T cells in response to Daudi cells is similar to that in humans, but the exposure to IL-2 stimulates preferentially the simian V delta 1 subset rather than the V gamma 9/V delta 2 subset as found in humans. Upon SIV infection of the monkeys, we observed a transient increase of the percentage of total gamma delta T cell and the V gamma 9 subset. gamma delta T cells from infected animals also express more activation markers such as CD69, CD44 and the memory marker CD45RO. However, they respond to a lesser degree to Daudi or IL-2 stimulation in the outgrowth experiments compared with uninfected animals, although the subset composition of total gamma delta T cells is similar in infected and uninfected animals. The results clearly indicate that gamma delta T cells in rhesus monkeys are influenced by SIV infection. The detailed analysis of the gamma delta T cell response to SIV infection can serve as a model for understanding human gamma delta T cell responses to HIV infections.

Gan, Y H; Pauza, C D; Malkovsky, M

1995-01-01

326

Somatic aberration induction in Tradescantia occidentalis by neutrons, x- and gamma-radiations. I. Dosimetry.  

PubMed

The dosimetry is described for an investigation of the induction of somatic aberrations in Tradescantia occidentalis by substantially mono-energetic neutrons in the energy range 100 keV to 15 MeV, by 200 keV X-rays and cobalt-60 gamma-radiation. Spectrometry was carried out for both neutrons and X-rays. Neutron fluence was measured by uranium fission chambers. Two types of ionization chamber were employed for dose measurement. One chamber was manufactured of CH-plastic and filled with acetylene and the other of graphite and filled with carbon dioxide. Dosimetry for X- and gamma-radiation was by means of lithium fluoride thermoluminescent dosemeters calibrated against a Victoreen ionization chamber. PMID:1084865

Dennis, J A; Delafield, H J; Peaple, L H; Boot, S J

1976-04-01

327

Three-dimensional radiation dosimetry for gamma knife using a gel dosimeter  

NASA Astrophysics Data System (ADS)

The use of three-dimensional radiation dosimetry has been limited. With the use of water phantoms and ionization chambers, it has been possible to determine three dimensional dose distributions on a gross scale for cobalt 60 and linear accelerator sources. This method has been somewhat useful for traditional radiotherapy. There is, however, a need for more precise dosimetry, particularly with stereotactic radiosurgery. Most gamma knife facilities use either thermoluminescant dosimetry or film, neither of which provides three dimensional dose distributions. To overcome this limitation, we have developed a gel dosimetry system that relies on the production of a ferric ion-xylenol orange colored complex. This work demonstrates the use of laser light and a detector to quantify radiation-induced colorimetric changes in absorbance for the gel dosimeter. The absorbance has been reconstructed by the back projection technique to demonstrate the applicability of the gel dosimeter to gamma knife 3D-dose distributions.

Hussain, Kazi Muazzam

328

A new natural gamma radiation measurement system for marine sediment and rock analysis  

NASA Astrophysics Data System (ADS)

A new high-efficiency and low-background system for the measurement of natural gamma radioactivity in marine sediment and rock cores retrieved from beneath the seabed was designed, built, and installed on the JOIDES Resolution research vessel. The system includes eight large NaI(Tl) detectors that measure adjacent intervals of the core simultaneously, maximizing counting times and minimizing statistical error for the limited measurement times available during drilling expeditions. Effect to background ratio is maximized with passive lead shielding, including both ordinary and low-activity lead. Large-area plastic scintillator active shielding filters background associated with the high-energy part of cosmic radiation. The new system has at least an order of magnitude higher statistical reliability and significantly enhances data quality compared to other offshore natural gamma radiation (NGR) systems designed to measure geological core samples. Reliable correlations and interpretations of cored intervals are possible at rates of a few counts per second.

Vasiliev, M. A.; Blum, P.; Chubarian, G.; Olsen, R.; Bennight, C.; Cobine, T.; Fackler, D.; Hastedt, M.; Houpt, D.; Mateo, Z.; Vasilieva, Y. B.

2011-11-01

329

Development and characterization of starch nanoparticles by gamma radiation: potential application as starch matrix filler.  

PubMed

Gamma radiation arises as an advantageous alternative to obtain starch nanoparticles given its low cost, simple methodology and scalability. Starch nanoparticles (SNP) with sizes around 20 and 30 nm were obtained applying a dose of 20 kGy from cassava (CNP-?) and waxy maize (WNP-?) starch, respectively. They showed the same thermal degradation behavior and their maximum mass loss zone was similar to those nanoparticles obtained from acid hydrolysis (WNP-h). Additionally, CNP-? and WNP-? were used as nanofillers in a cassava matrix. Increments of 102% in storage modulus were obtained with the addition of only 2.5 wt.% of WNP-?, showing that gamma radiation is a successful methodology to obtain SNP able to be used as starch reinforcement. PMID:23769521

Lamanna, Melisa; Morales, Noé J; García, Nancy Lis; Goyanes, Silvia

2013-05-03

330

Gamma radiation effects on erbium-doped fiber in superfluorescent fiber source  

NASA Astrophysics Data System (ADS)

The radiation effects of two erbium-doped superfluorescent fiber sources (SFSs) are studied in gamma ray environment. Two types of output spectrum profile (twin-peaked spectrum and single-peaked spectrum) of SFSs are constructed by different configuration and parameters. The dependence of radiation-induced power loss and spectra evolution on the dosage is revealed. The results show that the amplitudes of radiation-induced power decrease are quite similar in two SFSs. But the mean wavelength variation of the single-peaked spectrum SFS is approximately 25 times smaller than that of the twin-peaked spectrum SFS. Compared to the twin-peaked spectrum SFS, the single-peaked spectrum SFS presents better radiation tolerance, which should have potential advantages in space applications.

Liu, Chengxiang; Zhang, Li; Wu, Xu; Ruan, Shuangchen

2013-10-01

331

Interferon-gamma mediated up-regulation of caspase-8 sensitizes medulloblastoma cells to radio- and chemotherapy.  

PubMed

Loss of caspase-8 expression - which has been demonstrated in a subset of Medulloblastoma (MB) - might block important apoptotic signalling pathways and therefore contribute to treatment resistance. In this study, IFN-gamma mediated up-regulation of caspase-8 in human MB cells was found to result in chemosensitization to cisplatin, doxorubicin and etoposide, and sensitisation to radiation. These effects were more prominent in D425 and D341 MB cells (low basal caspase-8 expression) when compared to DAOY MB cells (high basal caspase-8 expression). IFN-gamma mediated chemosensitization and radiosensitization effects were reduced by treatment with the caspase-8 specific inhibitor z-IETD-fmk. Treatment of IFN-gamma resulted in activation of STAT1 in DAOY MB cells and to a lesser extent in D425, but not in D341, indicating that IFN-gamma acts in MB cells through STAT1-dependent and -independent signalling pathways. Taken together, our results demonstrate that IFN-gamma mediated restoration of caspase-8 in MB cells might enhance apoptotic pathways relevant to the response to chemo- and radiotherapy. PMID:17627812

Meister, N; Shalaby, T; von Bueren, A O; Rivera, P; Patti, R; Oehler, C; Pruschy, M; Grotzer, M A

2007-07-12

332

Comparison of radiation damage in lead tungstate crystals under pion and gamma irradiation  

SciTech Connect

Studies of the radiation hardness of lead tungstate crystals produced by the Bogoroditsk Techno-Chemical Plant in Russia and the Shanghai Institute of Ceramics in China have been carried out at IHEP, Protvino. The crystals were irradiated by a 40 GeV pion beam. After full recovery, the same crystals were irradiated using a {sup 137}Cs {gamma}-ray source. The dose rate profiles along the crystal length were observed to be quite similar. We compare the effects of the two types of radiation on the crystals light output.

Batarin, V.A.; Butler, J.; Davidenko, A.M.; Derevschikov, A.A.; Goncharenko, Y.M.; Grishin, V.N.; Kachanov, V.A.; Khodyrev, V.Y.; Konstantinov, A.S.; Kravtsov, V.I.; Kubota, Y.; Lukanin, V.S.; Matulenko, Y.A.; Melnick, Y.M.; Meschanin, A.P.; Mikhalin, N.E.; Minaev, N.G.; Mochalov, V.V.; Morozov, D.A.; Nogach, L.V.; Ryazantsev, A.V.; /Serpukhov, IHEP /Fermilab /Minnesota U. /Syracuse U. /Nanjing U.

2003-12-01

333

Gamma-radiation-induced wood-plastic composites from Syrian tree species  

NASA Astrophysics Data System (ADS)

Wood-plastic composites (WPC) have been prepared with five low-grade woods, native to Syria, using three monomer systems; acrylamide, butylmethacrylate, and styrene, with methanol as the swelling solvent. Polymerization was induced at various radiation doses (10, 20, and 30kGy) at a dose rate of 3.5kGy/h using a 60Co gamma radiation source. Some physical properties of WPC, namely polymer loading and compression strength have been measured. The polymer loading decreases approximately with increasing density of the wood species used.

Bakraji, E. H.; Salman, N.; Al-kassiri, H.

2001-05-01

334

Method for detecting water equivalent of snow using secondary cosmic gamma radiation  

DOEpatents

Water equivalent of accumulated snow determination by measurement of secondary background cosmic radiation attenuation by the snowpack. By measuring the attentuation of 3-10 MeV secondary gamma radiation it is possible to determine the water equivalent of snowpack. The apparatus is designed to operate remotely to determine the water equivalent of snow in areas which are difficult or hazardous to access during winter, accumulate the data as a function of time and transmit, by means of an associated telemetry system, the accumulated data back to a central data collection point for analysis. The electronic circuitry is designed so that a battery pack can be used to supply power.

Condreva, Kenneth J. (1420 Fifth St., Livermore, Alameda County, CA 94550)

1997-01-01

335

Method for detecting water equivalent of snow using secondary cosmic gamma radiation  

DOEpatents

Water equivalent of accumulated snow determination by measurement of secondary background cosmic radiation attenuation by the snowpack. By measuring the attenuation of 3-10 MeV secondary gamma radiation it is possible to determine the water equivalent of snowpack. The apparatus is designed to operate remotely to determine the water equivalent of snow in areas which are difficult or hazardous to access during winter, accumulate the data as a function of time and transmit, by means of an associated telemetry system, the accumulated data back to a central data collection point for analysis. The electronic circuitry is designed so that a battery pack can be used to supply power. 4 figs.

Condreva, K.J.

1997-01-14

336

Comparison of proton microbeam and gamma irradiation for the radiation hardness testing of silicon PIN diodes  

NASA Astrophysics Data System (ADS)

Simple and cost-effective solutions using Si PIN diodes as detectors are presently utilized in various radiation-related applications in which excessive exposure to radiation degrades their charge transport properties. One of the conventional methods for the radiation hardness testing of such devices is time-consuming irradiation with electron beam or gamma-ray irradiation facilities, high-energy proton accelerators, or with neutrons from research reactors. Recently, for the purpose of radiation hardness testing, a much faster nuclear microprobe based approach utilizing proton irradiation has been developed. To compare the two different irradiation techniques, silicon PIN diodes have been irradiated with a Co-60 gamma radiation source and with a 6 MeV proton microbeam. The signal degradation in the silicon PIN diodes for both irradiation conditions has been probed by the IBIC (ion beam induced charge) technique, which can precisely monitor changes in charge collection efficiency. The results presented are reviewed on the basis of displacement damage calculations and NIEL (non-ionizing energy loss) concept.

Jakši?, M.; Grilj, V.; Skukan, N.; Majer, M.; Jung, H. K.; Kim, J. Y.; Lee, N. H.

2013-09-01

337

EFFECT OF Co⁶°$gamma$ RADIATION ON VITAMIN Bâ-GROUP SUBSTANCES  

Microsoft Academic Search

When aqueous solutions of 0.030 mg\\/ml pyridoxine hydrochloride, ; pyridoxal hydrochloride, and pyridoxamine dihydrochloride, the pH of which had ; been adjusted to approximates 2 with 0.01N hydrochloric acid, were irradiated ; with Co⁶° gamma radiation at a dose of 10⁵ rep, the loss of the ; vitamin was 94, 77, and 70%, respectively. Losses of less than 10% were

Shiroishi

1961-01-01

338

Circular polarization of gamma-radiation after capture of polarized thermal neutrons  

Microsoft Academic Search

With a Ge(Li) spectrometer, the circular polarization of gamma-radiation due to capture of polarized thermal neutrons in K, Ca, Ti, Co, Cd and Pb was determined from transmission measurements through magnetized iron cobalt alloy. The following unambiguous spin assignments result from these measurements (Ex in keV); J(2290) = 2 in 40K; J(3174) = 1\\/2 in 49Ti; J(785) = 5 in

K. Abrahams; W. Ratynski

1969-01-01

339

Calicivirus Inactivation by Nonionizing (253.7-Nanometer-Wavelength [UV]) and Ionizing (Gamma) Radiation  

Microsoft Academic Search

Noroviruses (previously Norwalk-like viruses) are the most common viral agents associated with food- and waterborne outbreaks of gastroenteritis. In the absence of culture methods for noroviruses, animal calicivi- ruses were used as model viruses to study inactivation by nonionizing (253.7-nm-wavelength (UV)) and ionizing (gamma) radiation. Here, we studied the respiratory feline calicivirus (FeCV) and the presumed enteric canine calicivirus (CaCV)

A. M. de Roda Husman; Paul Bijkerk; Willemijn Lodder; Harold van den Berg; Walter Pribil; Alexander Cabaj; Peter Gehringer; Regina Sommer; Erwin Duizer

2004-01-01

340

Dose quantities and instrumentation for measuring environmental gamma radiation during emergencies  

Microsoft Academic Search

The dosimetry for exposure to gamma radiation in the environment is reviewed, including the factors used to convert measurements of traceable quantities to effective dose equivalent. A value of 0.70 Sv Gy-1 is widely used to convert air kerma or absorbed dose-to-air to effective dose equivalent, but recent work shows that a value of 0.86 Sv Gy-1 is more appropriate

M. J. Clark; P. H. Burgess; D. R. McClure

1993-01-01

341

Observation of the radiative decay J/psi. -->. gamma. eta. pi pi  

SciTech Connect

The radiative decay J/psi ..-->.. ..gamma.. eta ..pi pi.. has been observed in data taken with the Crystal Ball detector at the SPEAR e/sup +/e/sup -/ storage ring. In addition to the well-known eta', the eta ..pi pi.. mass spectrum shows a broad enhancement centered at approx. 1700 MeV. There is no explicit evidence for the l(1440) in the eta ..pi pi.. mass spectrum.

Newman-Holmes, C.

1982-09-01

342

Immobilization of Urease on (HEMA\\/IA) Hydrogel Prepared by Gamma Radiation  

Microsoft Academic Search

In the present study, the copolymeric hydrogels based on 2-hydroxyethyl methacrylate (HEMA) and itaconic acid (IA) were synthesized by gamma radiation induced radical polymerization, in order to examine the potential use of these hydrogels in immobilization of Citrullus vulgaris urease. Gelation and Swelling properties of PHEMA and copolymeric P (HEMA\\/IA) hydrogels with different IA contents (96.5\\/3.5, 94.4\\/5.6 and 92.5\\/7.5 mol)

Soha M. Hamdy; Samia El-Sigeny; Manal F. Abou Taleb

2008-01-01

343

Interaction of gamma Radiation and Temperature on the Determination of the Sterilizing Dose of Some Stored Products Pests.  

National Technical Information Service (NTIS)

The influence of temperature on sterilizing dosages of gamma radiation was studied for Sitophilus zeamais Mots. in corn, Sitophilus oryzae (L.) in rice, Araecerus fasciculatus (DeGeer) in coffee, and Zabrotes subfasciatus (Boh.) in beans. It was found tha...

A. P. Barbosa

1976-01-01

344

Results of calculations of external gamma radiation exposure rates from fallout and related radionuclide compositions. Operation Teapot, 1955  

SciTech Connect

This report presents data on calculated gamma radiation exposure rates and ground deposition of related radionuclides resulting from events that deposited detectable radioactivity outside the Nevada Test Site complex.

Hicks, H.G.

1981-07-01

345

Incidence of fruit flies on coffee and citrus and quarantine treatment of citrus fruits by gamma radiation.  

National Technical Information Service (NTIS)

The objective of this study was to evaluate the fruit fly infestation on coffee and citrus, and also to determine gamma radiation doses for immature stages of Ceratitis capitata and Anastrepha fraterculus, in order to satisfy quarantine regulations. Coffe...

A. Raga

1996-01-01

346

Environmental gamma radiation and fallout measurements in Finland, 1986-87. Supplement 2 to annual report STUK-A-74.  

National Technical Information Service (NTIS)

Results from a survey of environmental gamma radiation levels in Finland after the Chernobyl accident 1986 are presented. The measurements were made in 1986-87 by means of sensitive Geiger-counters and a gamma-spectrometer placed in cars. The results show...

H. Arvela H. Lemmelae L. Blomqvist M. Markkanen

1989-01-01

347

Branching fractions and CP-violating asymmetries in radiative B decays to {eta}K{gamma}  

SciTech Connect

We present measurements of the CP-violation parameters S and C for the radiative decay B{sup 0}{yields}{eta}K{sub S}{sup 0}{gamma}; for B{yields}{eta}K{gamma} we also measure the branching fractions and for B{sup +}{yields}{eta}K{sup +}{gamma} the time-integrated charge asymmetry A{sub ch}. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 465x10{sup 6} BB pairs produced in e{sup +}e{sup -} annihilation. The results are S=-0.18{sub -0.46}{sup +0.49}{+-}0.12, C=-0.32{sub -0.39}{sup +0.40}{+-}0.07, B(B{sup 0}{yields}{eta}K{sup 0}{gamma})=(7.1{sub -2.0}{sup +2.1}{+-}0.4)x10{sup -6}, B(B{sup +}{yields}{eta}K{sup +}{gamma})=(7.7{+-}1.0{+-}0.4)x10{sup -6}, and A{sub ch}=(-9.0{sub -9.8}{sup +10.4}{+-}1.4)x10{sup -2}. The first error quoted is statistical and the second systematic.

Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X.; Tisserand, V. [Laboratoire de Physique des Particules, IN2P3/CNRS et Universite de Savoie, F-74941 Annecy-Le-Vieux (France); Tico, J. Garra; Grauges, E. [Facultat de Fisica, Departament ECM, Universitat de Barcelona, E-08028 Barcelona (Spain); Eigen, G.; Stugu, B.; Sun, L. [University of Bergen, Institute of Physics, N-5007 Bergen (Norway); Abrams, G. S.; Battaglia, M.; Brown, D. N.; Cahn, R. N.; Jacobsen, R. G.; Kerth, L. T.; Kolomensky, Yu. G. [Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA and University of California, Berkeley, California 94720 (United States)] (and others)

2009-01-01

348

Branching Fractions and CP-Violating Asymmetries in Radiative B Decays to eta K gamma  

SciTech Connect

The authors present measurements of the CP-violation parameters S and C for the radiative decay B{sup 0} {yields} {eta}K{sub S}{sup 0}{gamma}; for B {yields} {eta}K{gamma} they also measure the branching fractions and for B{sup +} {yields} {eta}K{sup +}{gamma} the time-integrated charge asymmetry {Alpha}{sub ch}. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 465 x 10{sup 6} B{bar B} pairs produced in e{sup +}e{sup -} annihilation. The results are S = -0.18{sub -0.46}{sup +0.49} {+-} 0.12, C = -0.32{sub -0.39}{sup +0.40} {+-} 0.07, {Beta}(B{sup 0} {yields} {eta}K{sup 0}{gamma}) = (7.1{sub -2.0}{sup +2.1} {+-} 0.4) x 10{sup -6}, {Beta}(B{sup +} {yields} {eta}K{sup +}{gamma}) = (7.7 {+-} 1.0 {+-} 0.4) x 10{sup -6}, and {Alpha}{sub ch} = (-9.0{sub -9.8}{sup +10.4} {+-} 1.4) x 10{sup -2}. The first error quoted is statistical and the second systematic.

Aubert, B.

2008-05-14

349

umuC-dependent and umuC-independent gamma- and UV-radiation mutagenesis in Escherichia coli.  

PubMed

The effects of the umuC36 and umuC122::Tn 5 mutations on gamma- and UV radiation mutagenesis (nonsense, missense, and frameshift mutation assays) in Escherichia coli K12 were studied. Although both mutations reduced radiation mutagenesis, the umuC36 mutation appeared to be leaky since considerably more UV radiation mutagenesis could be detected in the umuC36 strain than in the umuC122::Tn 5 strain. In general, the umuC strain showed much larger deficiencies in UV radiation mutagenesis than they did for gamma-radiation mutagenesis. The mutability of the umuC122:: Tn 5 strain varied depending on the radiation dose, and the mutation assay used. For gamma-radiation mutagenesis, the deficiency varied from no deficiency to a 50-fold deficiency; for UV radiation mutagenesis, the deficiency varied from 100-fold to at least 5000-fold. We concluded that both umuC-dependent and umuC-independent modes function for gamma-radiation mutagenesis, while UV radiation mutagenesis seems to depend almost exclusively on the umuC-dependent mode. PMID:6088973

Sargentini, N J; Smith, K C

1984-08-01

350

Effects of gamma irradiation on the radiation-resistant bacteria and polyphenol oxidase activity in fresh kale juice  

Microsoft Academic Search

Gamma radiation was performed to prolong the shelf life of natural kale juice. The total aerobic bacteria in fresh kale juice, prepared by a general kitchen process, was detected in the range of 106cfu\\/ml, and about 102cfu\\/ml of the bacteria survived in the juice in spite of gamma irradiation treatment with a dose of 5kGy. Two typical radiation-resistant bacteria, Bacillus

Dongho Kim; Hyunpa Song; Sangyong Lim; Hyejeong Yun; Jinwoo Chung

2007-01-01

351

Protection by S-2-(3-aminopropylamino)ethylphosphorothioic acid against radiation-induced leg contractures in mice. [Gamma Radiation  

SciTech Connect

S-2-(3-Aminopropylamino)ethylphosphorothioic acid (WR-2721) was shown to provide marked protection against development of radiation-induced leg contractures in C3Hf/Kam mice whose legs were exposed to single doses of gamma-radiation. The radiation doses ranged from 3300 to 6200 rads delivered to the right hind thighs from two parallelly opposed 137Cs sources. WR-2721 was given i.p. 30 min before irradiation. The severity of radiation-induced leg contractures in untreated and WR-2721-treated mice was followed for 342 days after irradiation. The degree of leg contractures in both control and WR-2721-treated mice increased up to 100 days after radiation, when the change stabilized, remaining more or less at the same level to the end of the observation period. During this entire period, the severity of contractures was less in WR-2721-treated mice. The dose-modifying factor for the level of 5 mm reduction in leg extension was 1.5 at 182 days after irradiation. Since WR-2721 did not prevent the radiocurability of 8-mm fibrosarcomas growing in the same legs, these data imply that WR-2721 has a high potential for increasing therapeutic gain when combined with irradiation in the treatment of tumors of an appreciable size.

Hunter, N.; Milas, L.

1983-04-01

352

Cell lines derived from a medaka radiation-sensitive mutant have defects in DNA double-strand break responses.  

PubMed

It was reported that the radiation-sensitive Medaka mutant "ric1" has a defect in the repair of DNA double-strand breaks (DSBs) induced by gamma-rays during early embryogenesis. To study the cellular response of a ric1 mutant to ionizing radiation (IR), we established the mutant embryonic cell lines RIC1-e9, RIC1-e42, RIC1-e43. Following exposure to gamma-irradiation, the DSBs in wild-type cells were repaired within 1 h, while those in RIC1 cells were not rejoined even after 2 h. Cell death was induced in the wild-type cells with cell fragmentation, but only a small proportion of the RIC1 cells underwent cell death, and without cell fragmentation. Although both wild-type and RIC1 cells showed mitotic inhibition immediately after gamma-irradiation, cell division was much slower to resume in the wild-type cells (20 h versus 12 h). In both wild-type and RIC1 cells, Ser139 phosphorylated H2AX (gammaH2AX) foci were formed after gamma-irradiation, however, the gammaH2AX foci disappeared more quickly in the RIC1 cell lines. These results suggest that the instability of gammaH2AX foci in RIC1 cells cause an aberration of the DNA damage response. As RIC1 cultured cells showed similar defective DNA repair as ric1 embryos and RIC1 cells revealed defective cell death and cell cycle checkpoint, they are useful for investigating DNA damage responses in vitro. PMID:19952493

Hidaka, Masayuki; Oda, Shoji; Kuwahara, Yoshikazu; Fukumoto, Manabu; Mitani, Hiroshi

2009-12-01

353

Persistence of gamma-H2AX and 53BP1 foci in proliferating and nonproliferating human mammary epithelial cells after exposure to gamma-rays or iron ions  

SciTech Connect

To investigate {gamma}-H2AX (phosphorylated histone H2AX) and 53BP1 (tumour protein 53 binding protein No. 1) foci formation and removal in proliferating and non-proliferating human mammary epithelial cells (HMEC) after exposure to sparsely and densely ionizing radiation under different cell culture conditions. HMEC cells were grown either as monolayers (2D) or in extracellular matrix to allow the formation of acinar structures in vitro (3D). Foci numbers were quantified by image analysis at various time points after exposure. Our results reveal that in non-proliferating cells under 2D and 3D cell culture conditions, iron-ion induced {gamma}-H2AX foci were still present at 72 h after exposure, although 53BP1 foci returned to control levels at 48 h. In contrast in proliferating HMEC, both {gamma}-H2AX and 53BP1 foci decreased to control levels during the 24-48 h time interval after irradiation under 2D conditions. Foci numbers decreased faster after {gamma}-ray irradiation and returned to control levels by 12 h regardless of marker, cell proliferation status, and cell culture condition. Conclusions: The disappearance of radiation induced {gamma}-H2AX and 53BP1 foci in HMEC have different dynamics that depend on radiation quality and proliferation status. Notably, the general patterns do not depend on the cell culture condition (2D versus 3D). We speculate that the persistent {gamma}-H2AX foci in iron-ion irradiated non-proliferating cells could be due to limited availability of double strand break (DSB) repair pathways in G0/G1-phase, or that repair of complex DSB requires replication or chromatin remodeling.

Groesser, Torsten; Chang, Hang; Fontenay, Gerald; Chen, James; Costes, Sylvain V.; Barcellos-Hoff, Mary Helen; Parvin, Bahram; Rydberg, Bjorn

2010-12-22

354

Albendazole sensitizes cancer cells to ionizing radiation  

PubMed Central

Background Brain metastases afflict approximately half of patients with metastatic melanoma (MM) and small cell lung cancer (SCLC) and represent the direct cause of death in 60 to 70% of those affected. Standard of care remains ineffective in both types of cancer with the challenge of overcoming the blood brain barrier (BBB) exacerbating the clinical problem. Our purpose is to determine and characterize the potential of albendazole (ABZ) as a cytotoxic and radiosensitizing agent against MM and SCLC cells. Methods Here, ABZ's mechanism of action as a DNA damaging and microtubule disrupting agent is assessed through analysis of histone H2AX phosphorylation and cell cyle progression. The cytotoxicity of ABZ alone and in combination with radiation therapy is determined though clonogenic cell survival assays in a panel of MM and SCLC cell lines. We further establish ABZ's ability to act synergistically as a radio-sensitizer through combination index calculations and apoptotic measurements of poly (ADP-ribose) polymerase (PARP) cleavage. Results ABZ induces DNA damage as measured by increased H2AX phosphorylation. ABZ inhibits the growth of MM and SCLC at clinically achievable plasma concentrations. At these concentrations, ABZ arrests MM and SCLC cells in the G2/M phase of the cell cycle after 12 hours of treatment. Exploiting the notion that cells in the G2/M phase are the most sensitive to radiation therapy, we show that treatment of MM and SCLC cells treated with ABZ renders them more sensitive to radiation in a synergistic fashion. Additionally, MM and SCLC cells co-treated with ABZ and radiation exhibit increased apoptosis at 72 hours. Conclusions Our study suggests that the orally available antihelminthic ABZ acts as a potent radiosensitizer in MM and SCLC cell lines. Further evaluation of ABZ in combination with radiation as a potential treatment for MM and SCLC brain metastases is warranted.

2011-01-01

355

RADIATION SENSITIVITY AND QUALITY OF FRESH-CUT VEGETABLES EXPOSED TO GAMMA RADIATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Thirteen fresh-cut (minimally processed) vegetables (broccoli, cilantro, red cabbage, endive, parsley, green and red leaf lettuce, Iceberg and Romaine lettuce, spinach, carrots, green onions, and celery) plus alfalfa sprouts were gamma irradiated at doses up to 3 kGy at 0.5 kGy intervals. The sample...

356

Breast cancer stem cells and radiation  

NASA Astrophysics Data System (ADS)

The present studies explore the response of breast cancer stem cells (BCSC's) to radiation and the implications for clinical cancer treatment. Current cancer therapy eliminates bulky tumor mass but may fail to eradicate a critical tumor initiating cell population termed "cancer stem cells". These cells are potentially responsible for tumor formation, metastasis, and recurrence. Recently cancer stem cells have been prospectively identified in various malignancies, including breast cancer. The breast cancer stem cell has been identified by the surface markers CD44+/CD24 -(low). In vitro mammosphere cultures allow for the enrichment of the cancer stem cell population and were utilized in order to study differential characteristics of BCSC's. Initial studies found that BCSC's display increased radiation resistance as compared to other non-stem tumor cells. This resistance was accompanied by decreased H2AX phosphorylation, decreased reactive oxygen species formation, and increased phosphorylation of the checkpoint protein Chk1. These studies suggest differential DNA damage and repair within the BCSC population. Studies then examined the consequences of fractionated radiation on the BCSC population and found a two-fold increase in BCSC's following 5 x 3Gy. This observation begins to tie cancer stem cell self-renewal to the clinical stem cell phenomenon of accelerated repopulation. Accelerated repopulation is observed when treatment gaps increase between sequential fractions of radiotherapy and may be due to cancer stem cell symmetric self-renewal. The balance between asymmetric and symmetric stem cell division is vital for proper maintenance; deregulation is likely linked to cancer initiation and progression. The developmental Notch-1 pathway was found to regulate BCSC division. Over-expressing the constitutively active Notch-1-ICD in MCF7 cells produced an increase in the BCSC population. Additionally, radiation was observed to increase the expression of the Notch-1 ligand, Jagged-1, and this was complemented by radiation induced Notch-1 activation. Studies also linked hypoxia and BCSC renewal through Epo signaling. Treatment with rhEpo induced an increase in BCSC's, which again was due to rhEpo induced Jagged-1 expression and subsequent Notch-1 activation. This thesis suggests that radiation and rhEpo induce Jagged-1 expression in non-stem cells, which then induce Notch-1 activation in adjacent stem cells, and results in symmetric cancer stem cell self-renewal.

Phillips, Tiffany Marie

357

Size effects on gamma radiation response of magnetic properties of barium hexaferrite powders  

SciTech Connect

Little is currently known about the effects of gamma-ray irradiation on oxide magnet materials. In particular, the effect of particle size on radiation susceptibility was investigated. Two commercial powders of BaFe{sub 12}O{sub 19} were thoroughly characterized, then exposed to 1 MGy of gamma radiation from a {sup 60}Co source. AC susceptibility and DC magnetometry and Moessbauer spectroscopy were performed after irradiation and compared to pre-irradiated measurements. DC magnetization and AC susceptibility decreased for both samples with the relative change of DC magnetization being larger for the micrometer-sized particles and the relative change of the AC susceptibility being larger for the nanometer-sized particles. Moessbauer spectroscopy indicated a decrease in both the hyperfine fields and in their distribution for each Fe site, particularly in the larger particle sample. Decreases in susceptibility are believed to be due to radiation-induced amorphization at the particle surfaces as well as amorphization and nucleation of new crystallites at internal crystallite boundaries, resulting in overall reduction in the particle magnetic moment. This radiation damage mechanism is different than that seen in previous studies of neutron and heavy ion irradiation of BaFe{sub 12}O{sub 19}.

McCloy, John; Kukkadapu, Ravi; Crum, Jarrod; Johnson, Brad; Droubay, Tim [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

2011-12-01

358

Disinfection of domestic effluents by gamma radiation: effects on the inactivation of Ascaris lumbricoides eggs.  

PubMed

This work investigated the inactivation of Ascaris lumbricoides eggs in domestic effluents by gamma radiation from a (60)Co source. Domestic wastewater was treated in a compact demo-scale system consisting of a UASB reactor and a trickling filter; treatment was carried out at the Center for Research and Training on Sanitation (CePTS), Federal University of Minas Gerais, in Belo Horizonte-MG, Brazil. One-liter of treated wastewater samples was artificially contaminated with an average of 1000 non-embryonated Ascaris lumbricoides eggs from human feces; samples were then irradiated in a multiple-purpose irradiator at different doses (0.5-5 kGy). Eggs were recovered from the wastewater and the viability of these irradiated eggs was evaluated; the description of the egg developmental phases with each dose of gamma radiation was recorded. Radiation doses of 3.5 kGy effectively disinfected effluents with lower concentrations of A. lumbricoides eggs; higher radiation doses of 5 kGy were necessary to disinfect effluents with higher eggs concentrations. PMID:21911240

de Souza, Gloria S M B; Rodrigues, Ludmila A; de Oliveira, Warllem J; Chernicharo, Carlos A L; Guimarães, Marcos P; Massara, Cristiano L; Grossi, Pablo A

2011-08-23

359

Gallium arsenide solar cell radiation damage study  

SciTech Connect

An analysis has been made of electrons and proton damaged GaAs solar cells suitable for use in space. The authors find that although some electrical parametric data and spectral response data are quite similar, the type of damage due to the two types of radiation is different. An I {minus} V analysis model shows that electrons damage the bulk of the cell and its currents relatively more while protons damage the junction of the cell and its voltages more.

Maurer, R.H.; Herbert, G.A.; Kinnison, J.D. (The Johns Hopkins Univ., Applied Physics Lab., Laurel, MD (US)); Meulenberg, A. (COMSAT Lab., Clarksburg, MD (US))

1989-12-01

360

Effect of gamma radiation on enzymatic activity and sulphydryl groups of human erythrocyte membrane.  

PubMed

The effect of ionizing radiation on human erythrocyte ghost membranes was studied by following changes in membrane -SH groups and activities of four membrane bound enzymes: Na+K+Mg2+ ATP-ase, Mg2+Ca2+ ATP-ase, Na+K+ATP-ase, and AChE. Irradiation up to 100 Gy gamma X-rays produced a significant decrease in the activity of ATP-ase and an increase in AChE activity. At higher radiation doses a marked decrease in the activities of all the enzymes was observed. A correlation between radiation-induced perturbations in enzyme activities and changes in membrane -SH groups was found. PMID:6137463

Pa?ecz, D; Leyko, W

1983-09-01

361

GAMMA-RAY BURST PROMPT EMISSION: JITTER RADIATION IN STOCHASTIC MAGNETIC FIELD REVISITED  

SciTech Connect

We revisit the radiation mechanism of relativistic electrons in the stochastic magnetic field and apply it to the high-energy emissions of gamma-ray bursts (GRBs). We confirm that jitter radiation is a possible explanation for GRB prompt emission in the condition of a large electron deflection angle. In the turbulent scenario, the radiative spectral property of GRB prompt emission is decided by the kinetic energy spectrum of turbulence. The intensity of the random and small-scale magnetic field is determined by the viscous scale of the turbulent eddy. The microphysical parameters {epsilon}{sub e} and {epsilon}{sub B} can be obtained. The acceleration and cooling timescales are estimated as well. Due to particle acceleration in magnetized filamentary turbulence, the maximum energy released from the relativistic electrons can reach a value of about 10{sup 14} eV. The GeV GRBs are possible sources of high-energy cosmic-ray.

Mao, Jirong [International Center for Astrophysics, Korea Astronomy and Space Science Institute, 776, Daedeokdae-ro, Yuseong-gu, Daejeon 305-348 (Korea, Republic of); Wang Jiancheng, E-mail: jirong.mao@brera.inaf.it [Yunnan Observatory, Chinese Academy of Sciences, Kunming, Yunnan Province 650011 (China)

2011-04-10

362

Gamma-ray Burst Prompt Emission: Jitter Radiation in Stochastic Magnetic Field Revisited  

NASA Astrophysics Data System (ADS)

We revisit the radiation mechanism of relativistic electrons in the stochastic magnetic field and apply it to the high-energy emissions of gamma-ray bursts (GRBs). We confirm that jitter radiation is a possible explanation for GRB prompt emission in the condition of a large electron deflection angle. In the turbulent scenario, the radiative spectral property of GRB prompt emission is decided by the kinetic energy spectrum of turbulence. The intensity of the random and small-scale magnetic field is determined by the viscous scale of the turbulent eddy. The microphysical parameters epsilon e and epsilon B can be obtained. The acceleration and cooling timescales are estimated as well. Due to particle acceleration in magnetized filamentary turbulence, the maximum energy released from the relativistic electrons can reach a value of about 1014 eV. The GeV GRBs are possible sources of high-energy cosmic-ray.

Mao, Jirong; Wang, Jiancheng

2011-04-01

363

Luminescence radiation spectroscopy of silicon solar cells  

NASA Astrophysics Data System (ADS)

At present there are known many of diagnostic methods of detection large crystal lattice defects of silicon solar cells. This paper deals about results of new potential in to use one of characteristics luminescence radiation for detection defects of solar cells. So polarization spectroscopy of defect in solar cells may be used to fitting characterization of silicon solar cells. And this can lead to understand the electrical properties of defects in silicon solar cells and study of really formation defects. We used extending existing electroluminescence technology about polarization spectroscopy to yield the polarization of luminescence radiation by defect in solar cells. Radiation emitted by the solar cell has a wave character that can interact with the silicon structures or hypothetically thin reflectance layer of solar cells. In our research we can observed the linear partially polarization luminescence light on poly-silicon crack defect. Spectral response of using CCD camera is approximately 300 to 1100 nm. Sinusoid dependence of luminescence intensity on the angle of linear polarization analyzer rotation shown this fact. The degree of polarization depends on the material, in this case the character of defect. Polarized light can be obtained in various ways. This fact opens up for potential next new questions in this widely course of study diagnostics defects silicon solar cells.

Stojan, R.; Van?k, J.; Malý, M.; Gvritishvili, R.; Tománek, P.; Frantík, O.

2013-09-01

364

In situ determination of radon concentration and total gamma radiation in Kastel Gomilica, Croatia  

NASA Astrophysics Data System (ADS)

To determine current radiation background of the environment at the “Giricic” location in Kastel Gomilica, Croatia, in situ measurement of radon concentration (222Rn and 220Rn) in an open atmosphere on a ground level and at the height of 1.5 m has been made as well as total gamma radiation at the height of 1 m in an energy range of 15 keV to 2 MeV. The researched location was divided in three specific parts: (i) regulated area with the bottom ash and flying ash in the basis (“old” depot), (ii) unregulated area with waste materials, including bottom ash and flying ash, in the basis (“new” depot), (iii) uncontaminated area with no waste materials deposited on. Average radon concentration on a ground level was 213 Bq/m3 for the “old” depot, 214 Bq/m3 for the “new” depot and 59 Bq/m3 for the uncontaminated area and at the height of 1.5 m 20 Bq/m3 for the “old” depot, 34 Bq/m3 for the “new” depot and 26 Bq/m3 for the uncontaminated area. Average total gamma radiation values in selected energy range were 109.92 cps (counts per second) for the “old” depot, 357.76 cps for the “new” depot and 65.97 cps for the uncontaminated area. For selected radionuclides (214Pb, 137Cs, 228Ac, 234mPa, 40K and 214Bi) average gamma radiation values at characteristic energies have been determined as well.

Lovrencic, Ivanka; Barisic, Delko; Orescanin, Visnja; Lulic, Stipe

2007-10-01

365

Complete suppression of reverse annealing of neutron radiation damage during active gamma irradiation in MCZ Si detectors  

NASA Astrophysics Data System (ADS)

For the development of radiation-hard Si detectors for the SiD BeamCal (Si Detector Beam Calorimeter) program for International Linear Collider (ILC), n-type Magnetic Czochralski Si detectors have been irradiated first by fast neutrons to fluences of 1.5×1014 and 3×1014 neq/cm2, and then by gamma up to 500 Mrad. The motivation of this mixed radiation project is to test the radiation hardness of MCZ detectors that may utilize the gamma/electron radiation to compensate the negative effects caused by neutron irradiation, all of which exists in the ILC radiation environment. By using the positive space charge created by gamma radiation in MCZ Si detectors, one can cancel the negative space charge created by neutrons, thus reducing the overall net space charge density and therefore the full depletion voltage of the detector. It has been found that gamma radiation has suppressed the room temperature reverse annealing in neutron-irradiated detectors during the 5.5 month of time needed to reach a radiation dose of 500 Mrad. The room temperature annealing (RTA) was verified in control samples (irradiated to the same neutron fluences, but going through this 5.5 month RTA without gamma radiation). This suppression is in agreement with our previous predictions, since negative space charge generated during the reverse annealing was suppressed by positive space charge induced by gamma radiation. The effect is that regardless of the received neutron fluence the reverse annealing is totally suppressed by the same dose of gamma rays (500 Mrad). It has been found that the full depletion voltage for the two detectors irradiated to two different neutron fluences stays the same before and after gamma radiation. Meanwhile, for the control samples also irradiated to two different neutron fluences, full depletion voltages have gone up during this period. The increase in full depletion voltage in the control samples corresponds to the generation of negative space charge, and this increase in concentration of negative space charge goes up with the neutron fluence. If we assume the reverse annealing is also taking place for the two gamma-irradiated samples with similarly different concentrations of negative space charge generated, the observed effect of no changes in space charge (no changes in Vfd) in these two gamma-irradiated samples would imply that concentrations of positive space charge created in these two control samples are different at the same gamma dose, and gamma irradiation effectively "switched off", the RT (room temperature) reverse annealing of neutron irradiation. It has also been found that as soon as the gamma irradiation stops, the RT reverse annealing of neutron irradiation-induced defects resumes with same rate as that of the control detectors. This behavior in mixed radiation samples (neutron plus gamma) would suggest some nonlinear effect (defects induced by mixed-radiations are not additive of those by individual radiation alone), or interaction of radiation induced acceptor-type and donor-type defects.

Li, Z.; Verbitskaya, E.; Chen, W.; Eremin, V.; Gul, R.; Härkönen, J.; Hoeferkamp, M.; Kierstead, J.; Metcalfe, J.; Seidel, S.

2013-01-01

366

Deinococcus swuensis sp. nov., a gamma-radiation-resistant bacterium isolated from soil.  

PubMed

Strain DY59(T), a Gram-positive non-motile bacterium, was isolated from soil in South Korea, and was characterized to determine its taxonomic position. Phylogenetic analysis based on the 16S rRNA gene sequence of strain DY59(T) revealed that the strain DY59(T) belonged to the family Deinococcaceae in the class Deinococci. The highest degree of sequence similarities of strain DY59(T) were found with Deinococcus radiopugnans KACC 11999(T) (99.0%), Deinococcus marmoris KACC 12218(T) (97.9%), Deinococcus saxicola KACC 12240(T) (97.0%), Deinococcus aerolatus KACC 12745(T) (96.2%), and Deinococcus frigens KACC 12220(T) (96.1%). Chemotaxonomic data revealed that the predominant fatty acids were iso-C15:0 (19.0%), C16:1 ?7c (17.7%), C15:1 ?6c (12.6%), iso-C17:0 (10.3%), and iso-C17:1 ?9c (10.3%). A complex polar lipid profile consisted of a major unknown phosphoglycolipid. The predominant respiratory quinone is MK-8. The cell wall peptidoglycan contained D-alanine, L-glutamic acid, glycine, and L-ornithine (di-amino acid). The novel strain showed resistance to gamma radiation, with a D10 value (i.e. the dose required to reduce the bacterial population by 10-fold) in excess of 5 kGy. Based on the phylogenetic, chemotaxonomic, and phenotypic data, strain DY59(T) (=KCTC 33033(T) =JCM 18581(T)) should be classified as a type strain of a novel species, for which the name Deinococcus swuensis sp. nov. is proposed. PMID:23812810

Lee, Jae-Jin; Lee, Hyun Ji; Jang, Gi Seon; Yu, Ja Myoung; Cha, Ji Yoon; Kim, Su Jeong; Lee, Eun Bit; Kim, Myung Kyum

2013-06-28

367

Transfer and expression of the interferon gamma gene in human endothelial cells inhibits vascular smooth muscle cell growth in vitro.  

PubMed

Intimal hyperplasia in blood vessels is primarily caused by the migration and proliferation of vascular smooth muscle cells. Excessive intimal thickening characterizes atherosclerosis as well as bypass graft and angioplasty failures. Endothelial cell-smooth muscle cell interactions and local cytokine production are important regulators of smooth muscle cell growth. Interferon gamma (gamma-IFN), a product of T lymphocytes found in atherosclerotic lesions, inhibits smooth muscle cell proliferation in vitro. To determine if local delivery of gamma-IFN may be useful in the treatment or prevention of vascular proliferative diseases, we transferred the human gamma-IFN gene into endothelial cells isolated from human arteries and microvessels using a retroviral vector. Biologically active gamma-IFN was produced and secreted by gamma-IFN transduced endothelial cells, but not by control, nontransduced cells, or cells identically transduced with E. coli beta galactosidase (beta-gal). To more closely approximate the microenvironment of blood vessels, subconfluent smooth muscle cells were plated in coculture with control, nontransduced endothelial cells, gamma-IFN transduced endothelial cells, or beta-gal transduced endothelial cells. Smooth muscle cell growth was inhibited 30-70% by coculture with gamma-IFN transduced endothelial cells compared to coculture with beta-gal transduced or control endothelial cells (p < 0.05). Our results suggest endothelial cells modified to produce gamma-IFN may be a useful therapy in proliferative vascular diseases. PMID:9040949

Stopeck, A T; Vahedian, M; Williams, S K

368

Age and radiation sensitivity of rat mammary clonogenic cells  

SciTech Connect

The relative risk of breast cancer is very high among women who were exposed to ionizing radiation during or before puberty. In the current studies, the surviving fractions of clonogenic mammary cells of groups of virgin rats were estimated after single exposures to {sup 137}Cs {gamma} rays at intervals from 1 to 12 weeks after birth. The radiosensitivity of clonogens from prepubertal rats was high and changed with the onset of puberty at between 4 and 6 weeks of age. By this time, the increase in the size of the clonogenic cell subpopulation was slowing and differentiation of terminal mammary end buds and alveolar structures was occurring. Analysis of the relationship of clonogen survival and radiation dose according to the {alpha}/{beta} model showed that the exponential {alpha}D term predominated at the second and fourth weeks of age. By the eighth week of age, the {beta}D{sup 2} term had come to predominate and the survival curve had a pronounced initial convex shoulder. Further experiments are required to determine whether there is an association between the high sensitivity of the prepubertal and pubertal mammary clonogens to radiation killing and a high susceptibility to radiogenic initiation of cancer. 24 refs., 4 figs., 1 tab.

Shimada, Yoshiya; Yasukawa-Barnes, J.; Kim, R.Y.; Gould, M.N.; Clifton, K.H. [Univ. of Wisconsin, Madison, WI (United States)

1994-01-01

369

Gamma-radiation-induced changes in structure and properties of tetracalcium phosphate and its derived calcium phosphate cement.  

PubMed

The purpose of the present study was to investigate the gamma-radiation effect on the structure and properties of the single-phase tetracalcium phosphate (TTCP) powder and its derived calcium phosphate cement (CPC). Experimental results show that low-dosed (0-30 kGy) CPC has a setting time of 10-12 min, while high-dosed (40-120 kGy) CPC has a setting time of 8-10 min. The low dose gamma-radiation does not significantly change porosity volume fraction or compressive strength of the CPC. The pH values of all CPC samples fell in a relatively narrow band, with a band width of 8.5-9.1 (in terms of pH value). With a dose of 10 or 20 kGy gamma-radiation, the TTCP-apatite conversion ratio does not change much. With 30 kGy the conversion ratio significantly increases and reaches a maximum value. With further increases in dose, the conversion ratio quickly declines. With increasing gamma-ray dose, the CPC morphology becomes more porous/loose and apatite particles become larger in size. When exposed to a high dose (120 kGy) of gamma-radiation, TTCP structure is radiation-damaged, and gamma-ray-induced formation of apatite is confirmed by transmission electron microscopic/selected-area diffraction/lattice imaging analyses. PMID:16850475

Tsai, Chih-Hung; Lin, Jiin-Huey Chern; Ju, Chien-Ping

2007-01-01

370

Kinetics of the radiation-induced radicals in gamma irradiated solid cefazolin sodium  

NASA Astrophysics Data System (ADS)

Room and high temperature kinetic and spectroscopic features of the radical species produced in gamma irradiated cefazolin sodium (here after CS) were investigated in detail using electron spin resonance (ESR) spectroscopy to determine the feasibility of its sterilization by radiation and to explore the dosimetric properties of this semi-synthetic representative of cephalosporins. Irradiated CS exhibits an unresolved ESR doublet as other cephalosporins reported up to date. Signal intensity data derived from microwave saturation, dose-response, decays at room and at high temperature studies were analysed assuming a model of two radical species giving rise to doublet and singlet ESR signals. Spectroscopic parameters of these species were determined through spectrum simulation calculations. Decay parameters calculated from annealing studies at seven different temperatures were used to calculate the activation energies of the contributing species. Radiosensitivity of CS to gamma rays was found to be relatively low in the dose range of 0-25 kGy. This conclusion was considered as an indication of the feasibility of radiosterilization of CS by gamma radiation. Five different functions were tried to explore dose-response data of CS in the dose range of 0-25 kGy and it was concluded that a function comprising a linear and a quadratic terms of applied dose describes best experimental results.

Yurus, S.; Korkmaz, M.

2005-01-01

371

Measurements of gamma radiation levels and spectra in the San Francisco Bay Area  

NASA Astrophysics Data System (ADS)

Much of the radiation received by an average person is emitted by naturally-occurring radioactive isotopes from the thorium, actinium, and uranium decay series, or potassium. In this study, we have measured gamma radiation levels at various locations in the San Francisco Bay Area and the UC Berkeley campus from spectra taken using an ORTEC NOMAD portable data acquisition system and a large-volume coaxial HPGe detector. We have identified a large number of gamma rays originating from natural sources. The most noticeable isotopes are ^214Bi, ^40K, and ^208Tl. We have observed variations in counting rates by factors of two to five between different locations due to differences in local conditions -- such as building, concrete, grass, and soil compositions. In addition, in a number of outdoor locations, we have observed 604-, 662-, and 795-keV gamma rays from ^134,137Cs, which we attribute to fallout from the recent Fukushima reactor accident. The implications of these results will be discussed.

Lo, B. T.; Brozek, K. P.; Angell, C. T.; Norman, E. B.

2011-10-01

372

Effect of gamma radiation on growth and survival of common seed-borne fungi in India  

NASA Astrophysics Data System (ADS)

The present work describes radiation-induced effects of major seeds like Oryza sativa Cv-2233, Oryza sativa Cv-Shankar, Cicer arietinum Cv-local and seed-borne fungi like Alternaria sp., Aspergillus sp., Trichoderma sp. and Curvularia sp. 60Co gamma source at 25 °C emitting gamma ray at 1173 and 1332 keV energy was used for irradiation. Dose of gamma irradiation up to 3 kGy (0.12 kGy/h) was applied for exposing the seed and fungal spores. Significant depletion of the fungal population was noted with irradiation at 1 2 kGy, whereas germinating potential of the treated grain did not alter significantly. However, significant differential radiation response in delayed seed germination, colony formation of the fungal spores and their depletion of growth were noticed in a dose-dependent manner. The depletion of the fungal viability (germination) was noted within the irradiation dose range of 1 2 kGy for Alternaria sp. and Aspergillus sp., while 0.5 1 kGy for Trichoderma sp. and Curvularia sp. However, complete inhibition of all the selected fungi was observed above 2.5 kGy.

Maity, J. P.; Chakraborty, A.; Chanda, S.; Santra, S. C.

2008-07-01

373

Single-cell responses to ionizing radiation.  

PubMed

While gene expression studies have proved extremely important in understanding cellular processes, it is becoming more apparent that there may be differences in individual cells that are missed by studying the population as a whole. We have developed a qRT-PCR protocol that allows us to assay multiple gene products in small samples, starting at 100 cells and going down to a single cell, and have used it to study radiation responses at the single-cell level. Since the accuracy of qRT-PCR depends greatly on the choice of "housekeeping" genes used for normalization, initial studies concentrated on determining the optimal panel of such genes. Using an endogenous control array, it was found that for IMR90 cells, common housekeeping genes tend to fall into one of two categories-those that are relatively stably expressed regardless of the number of cells in the sample, e.g., B2M, PPIA, and GAPDH, and those that are more variable (again regardless of the size of the population), e.g., YWHAZ, 18S, TBP, and HPRT1. Further, expression levels in commonly studied radiation-response genes, such as ATF3, CDKN1A, GADD45A, and MDM2, were assayed in 100, 10, and single-cell samples. It is here that the value of single-cell analyses becomes apparent. It was observed that the expression of some genes such as FGF2 and MDM2 was relatively constant over all irradiated cells, while that of others such as FAS was considerably more variable. It was clear that almost all cells respond to ionizing radiation but the individual responses were considerably varied. The analyses of single cells indicate that responses in individual cells are not uniform and suggest that responses observed in populations are not indicative of identical patterns in all cells. This in turn points to the value of single-cell analyses. PMID:23995963

Ponnaiya, Brian; Amundson, Sally A; Ghandhi, Shanaz A; Smilenov, Lubomir B; Geard, Charles R; Buonanno, Manuela; Brenner, David J

2013-08-31

374

Single-cell responses to ionizing radiation  

PubMed Central

While gene expression studies have proved extremely important in understanding cellular processes, it is becoming more apparent that there may be differences in individual cells that are missed by studying the population as a whole. We have developed a qRT-PCR protocol that allows us to assay multiple gene products in small samples, starting at 100 cells and going down to a single cell, and have used it to study radiation responses at the single-cell level. Since the accuracy of qRT-PCR depends greatly on the choice of “housekeeping” genes used for normalization, initial studies concentrated on determining the optimal panel of such genes. Using an endogenous control array, it was found that for IMR90 cells, common housekeeping genes tend to fall into one of two categories—those that are relatively stably expressed regardless of the number of cells in the sample, e.g., B2M, PPIA, and GAPDH, and those that are more variable (again regardless of the size of the population), e.g., YWHAZ, 18S, TBP, and HPRT1. Further, expression levels in commonly studied radiation-response genes, such as ATF3, CDKN1A, GADD45A, and MDM2, were assayed in 100, 10, and single-cell samples. It is here that the value of single-cell analyses becomes apparent. It was observed that the expression of some genes such as FGF2 and MDM2 was relatively constant over all irradiated cells, while that of others such as FAS was considerably more variable. It was clear that almost all cells respond to ionizing radiation but the individual responses were considerably varied. The analyses of single cells indicate that responses in individual cells are not uniform and suggest that responses observed in populations are not indicative of identical patterns in all cells. This in turn points to the value of single-cell analyses.

Amundson, Sally A.; Ghandhi, Shanaz A.; Smilenov, Lubomir B.; Geard, Charles R.; Buonanno, Manuela; Brenner, David J.

2013-01-01

375

Features of the action of low-energy gamma radiation on the hydrogen permeability of certain materials  

SciTech Connect

This paper determines the diffusion coefficients, the constants of permeability, and solubility of hydrogen in palladium, nickel, and Armco iron under the action of low-energy gamma radiation. It was established that without radiation all of the kinetic diffusion curves of hydrogen in palladium and nickel straighten well in a functional scale. In armco iron, some deviations are observed.

Tazhibaeva, I.L.; Bekman, I.N.; Rudenko, N.V.; Shestakov, V.P.

1985-07-01

376

Recurrent tumor vs radiation effects after Gamma Knife radiosurgery of intracerebral metastases: Diagnosis with PET-FDG  

Microsoft Academic Search

Our objective was to differentiate radiation effects from tumor progression in metastases stereotaxically irradiated with the multicobalt unit (Gamma Knife). Eleven patients with stereotaxically irradiated cerebral metastases were examined with PET using [¹⁸F]fluorodeoxyglucose (FDG) to differentiate recurrent tumor from radiation effects. Six patients had increased uptake of FDG, and clinical, radiological, and pathological findings confirmed the diagnosis of recurrent metastases.

Jan Mogard; L. Kihlstroem; Kaj Ericson; Bengt Karlsson; Wan-Yuo Guo; Sharon Stone-Elander

1994-01-01

377

Atypical radiation response of SCID cells  

NASA Astrophysics Data System (ADS)

Murine SCID (severe combined immune deficiency) cells are well known for their defect in DNA double-strand break repair and in variable(diversity)joining [V(D)J] recombination due to a mutation in a catalytic subunit of DNA-dependent protein kinase (DNA-PKcs). As a consequence, scid cells are hypersensitive to ionizing radiation. The present study showed that asynchronous populations of scid cells were about two-fold more sensitive than Balb/c with respect to cell killing and the defect in scid cells was corrected by complementation with human chromosome 8. Analysis of the survival of synchronized populations as a function of the cell cycle revealed that while scid cells were hypersensitive in all cell cycle phases compared to wild-type cells, this hypersensitivity is even more pronounced in G1 phase. The hypersensitivity reduced as the cells progressed into S phase suggested that homologous recombination repair plays a role. The results imply that there are at least two pathways for the repair of DSB DNA, consistent with a model previously proposed by others. The scid cells were also more sensitive to UVC light (254 nm) killing as compared to wild type cells by clonogenic survival. Using a host cell reactivation (HCR) assay to study the nucleotide excision repair (NER) which is the major repair pathway for UV-photoproducts, the results showed that NER in scid cells was not as efficient as CB- 17. This suggests that DNA-PK is involved in NER as well as non-homologous end-joining (NHEJ) DSB repair which is responsible for ionizing radiation sensitivity in scid cells. Repair in scid cells was not totally absent as shown by low dose rate sparing of cell killing after exposure to 137Cs ?-rays at dose rate of 0.6 cGy/h, 1.36 cGy/h, 6 cGy/h as compared to high dose rate at 171 cGy/min, although this phenomenon could be explained partly by proliferation. However, for radiation induced transformation, no significant dose rate effect was seen. A plot of transformation versus survival revealed that the transformation induction was inversely proportional to radiation dose rate. Lower dose rates were more effective in inducing transformation in scid cells. This finding could lead to the influence of cancer risk estimation in an irradiated population consisting of a subpopulation(s) with genetic disorders predisposing those individuals to cancer.

Chawapun, Nisa

378

Induction of transpositions of MGE Dm412 by {gamma}-radiation in an isogenic line of Drosophila melanogaster  

SciTech Connect

In an isogenic line of Drosophila, transpositions of mobile genetic elements (MGE) Dm412 were induced by {gamma}-radiation at doses of 300, 800, and 1300 R. The rates of induced transpositions were (for each dose, respectively) 3.9 x 10{sup {minus}3}, 1.0 x 10{sup {minus}2}, and 1.87 x 10{sup {minus}2} events per occupied site per haploid genome of the isogenic line per generation. Thus, the transposition rate increased linearly with the radiation dose. The specific rate of {gamma}-radiation-induced transpositions was (1.3 {+-} 0.6) x 10{sup {minus}5} per occupied site per haploid genome of the isogenic line per Roentgen per generation. {gamma}-Radiation-induced hot transposition sites and haplotypes, very similar to those induced by heat shock, were found. It was suggested that the mechanism of induction by {gamma}-radiation involves the heat shock system. Thus, it is more similar to the mechanism of temperature induction than to the direct mutational effect of {gamma}-radiation. Estimates of induced transposition rates per genome for each dose were calculated as 1.1, 3.0, and 5.6 events, respectively, per genome per generation. This level probably corresponds to the subthreshold level of genomes near the {open_quotes}catastrophic border of transpositional losses.{close_quotes} 21 refs., 1 fig., 4 tabs.

Zabanov, S.A. [Institute of Cytology and Genetics, Novosibirsk (Russian Federation); Vasil`eva, L.A.; Ratner, V.A. [Institute of Cytology and Genetics, Novosibirsk (Russian Federation)]|[Novosibirsk State Univ. (Russian Federation)

1995-06-01

379

Proteomic analysis of global changes in protein expression during exposure of gamma radiation in Bacillus sp. HKG 112 isolated from saline soil.  

PubMed

A Gram-positive bacterium was isolated from the saline soils of Jangpura (U.P.), India, and showed high-level of radiation-resistant property and survived upto 12.5 kGy dose of gamma radiation. The 16S rDNA sequence of this strain was examined, identified as Bacillus sp. strain HKG 112, and was submitted to the NCBI GenBank (Accession No. GQ925432). The mechanism of radiation resistance and gene level expression were examined by proteomic analysis of whole-cell extract. Two proteins, 38 kDa and 86.5 kDa excised from SDS-PAGE, which showed more significant changes after radiation exposure, were identified by MALDI-TOF as being flagellin and S-layer protein, respectively. Twenty selected 2-DE protein spots from the crude extracts of Bacillus sp. HKG 112, excised from 2- DE, were identified by liquid chromatography mass spectrometry (LC-MS) out of which 16 spots showed significant changes after radiation exposure and might be responsible for the radiation resistance property. Our results suggest that the different responses of some genes under radiation for the expression of radiation-dependent proteins could contribute to a physiological advantage and would be a significant initial step towards a full-system understanding of the radiation stress protection mechanisms of bacteria in different environments. PMID:21715963

Gupta, Anil Kumar; Pathak, Rajiv; Singh, Bharat; Gautam, Hemlata; Kumar, Ram; Kumar, Raj; Arora, Rajesh; Gautam, Hemant

2011-06-01

380

Squamous cell carcinoma antigen suppresses radiation-induced cell death  

PubMed Central

Previous study has demonstrated that squamous cell carcinoma antigen (SCCA) 1 attenuates apoptosis induced by TNF?, NK cell or anticancer drug. In this study, we have examined the effect of SCCA2, which is highly homologous to SCCA1, but has different target specificity, against radiation-induced apoptosis, together with that of SCCA1. We demonstrated that cell death induced by radiation treatment was remarkably suppressed not only in SCCA1 cDNA-transfected cells, but also in SCCA2 cDNA-transfected cells. In these transfectants, caspase 3 activity and the expression of activated caspase 9 after radiation treatment were suppressed. Furthermore, the expression level of phosphorylated p38 mitogen-activated protein kinase (p38 MAPK) was suppressed compared to that of the control cells. The expression level of upstream stimulator of p38 MAPK, phosphorylated MKK3/MKK6, was also suppressed in the radiation-treated cells. Thus, both SCCA1 and SCCA2 may contribute to survival of the squamous cells from radiation-induced apoptosis by regulating p38 MAPK pathway. © 2001 Cancer Research Campaign http://www.bjcancer.com

Murakami, A; Suminami, Y; Hirakawa, H; Nawata, S; Numa, F; Kato, H

2001-01-01

381

Host-cell reactivation of gamma-irradiated phage T1 in strains of Escherichia coli K-12  

Microsoft Academic Search

Host-cell reactivation of gamma-irradiated phage T1 in strains of E. coli K-12 has been compared with HCR of UV-irradiated phage in these same strains and with the radiation sensitivities of these strains (Fig. 1–4). The pattern of the HCR of gammairradiated phage in these strains is like that of the HCR of UV-irradiated phage. HCR in strains whose genotype is

Raymond Meyn; Benjamin Friesen; Jeremy Baptist

1969-01-01

382

Cell fusion by ionizing radiation.  

National Technical Information Service (NTIS)

The relevance and importance of cell fusion are illustrated by the notion that current interest in this phenomenon is shared by scientists in quite varied disciplines. The diversity of cellular membrane fusion phenomena could provoke one to think that the...

M. B. Khair

1993-01-01

383

Effect of gamma cobalt ($gamma$ ⁶°Co) radiation on the growth and alkaloidal contents of medicinal plants. Part I. Hyoscyamus niger L. (Solanaceae)  

Microsoft Academic Search

Henbane (Hyoscyamus niger) is cultivated for the biosynthesis of ; alkaloids, especially hyoscyamine, used by the pharmaceutical industry that are ; present in most plant parts, particularly in the leaves and flowering tops. ; Seeds of henbane were irradiated with doses of 1, 1.5, 2, 2.5, or 3 Krads gamma ; radiation, and plants grown from the irradiated seeds were

S. Malik; M. Akram; N. A. Malik

1972-01-01

384

Decontamination du poivre noir et du poivre rouge par irradiation gamma. (Decontamination of black pepper and red pepper by gamma radiation).  

National Technical Information Service (NTIS)

In the present work, it has been studied the decontamination of two types of spices (black pepper and red pepper) by gamma radiation. The initial microbial population of spices not treated is about 10 (7) to 10 (8) per gram. The population decrease expone...

S. Oularbi B. Mansouri

1993-01-01

385

Radiative-neutron-capture gamma-ray analysis by a linear combination technique  

USGS Publications Warehouse

The linear combination technique, when applied to a gamma-ray spectrum, gives a single number indicative of the extent to which the spectral lines of a sought element are present in a complex spectrum. Spectra are taken of the sought element and of various other substances whose spectra interfere with that of the sought element. A weighting function is then computed for application to spectra of unknown materials. The technique was used to determine calcium by radiative-neutron-capture gamma-ray analysis in the presence of interfering elements, notably titanium, and the results were compared with those for two popular methods of peak area integration. Although linearity of response was similar for the methods, the linear combination technique was much better at rejecting interferences. For analyses involving mixtures of unknown composition the technique consequently offers improved sensitivity. ?? 1972.

Tanner, A. B.; Bhargava, R. C.; Senftle, F. E.; Brinkerhoff, J. M.

1972-01-01

386

Size Effects on Gamma Radiation Response of Magnetic Properties of Barium Hexaferrite Powders  

SciTech Connect

Little is currently known about the effects of gamma-ray irradiation on oxide magnet materials. In particular, the effect of particle size on radiation susceptibility was investigated. Two commercial powders of BaFe12O19 were thoroughly characterized, then exposed to 1 MGy of gamma radiation from a 60Co source. AC susceptibility and DC magnetometry and Moessbauer spectroscopy were performed after irradiation and compared to pre-irradiated measurements. DC magnetization and AC susceptibility decreased for both samples with the relative change of DC magnetization being larger for the micrometer-sized particles and the relative change of the AC susceptibility being larger for the nanometer-sized particles. Moessbauer spectroscopy indicated a decrease in both the hyperfine fieldsand in the distribution of hyperfine fields for each Fe site, particularly in the larger particle sample. Decreases in susceptibility are believed to be due to recrystallization of the particles and redistribution of an amorphous component, in the bulk or on the surface, and consequent reduction in the particle magnetic moment. This radiation damage mechanism is different than that seen in previous studies of neutron and heavy ion irradiation of BaFe12O19.

McCloy, John S.; Kukkadapu, Ravi K.; Crum, Jarrod V.; Johnson, Bradley R.; Droubay, Timothy

2011-12-08

387

Gamma radiation dosimetry using transmission and reflection spectroscopy of KClxBr1-x as TL crystals  

NASA Astrophysics Data System (ADS)

In this article we have shown that it is possible to use transmission, absorption and reflection spectroscopic data of KClxBr1-x single crystals for the TL (Thermo Luminescence) dosimetry purposes in the spectral range of 250-750 nm. The effects of gamma radiation on KClxBr1-x single crystals were investigated by radiating the samples with a 60Co source and studying the reflection and absorption spectra. Six doses of gamma radiation of 145, 300, 450, 600, 750 and 900 Gy were examined. The absorption peak height in the spectral region of 560-580 nm is in a direct relationship with the gamma radiation doses up to about 800 Gy, in which saturation starts to occur. The intensities of the color centers in mixed crystals are different by their combination ratios of the components contents. According to the reflection and transmission data, the absorption spectra can be calculated and a calibration curve sketched.

Ahad Bagheri, S.; Malekfar, R.

2010-03-01

388

Inhibition of radiation-enhanced expression of integrin and metastatic potential in B16 melanoma cells by a lipoxygenase inhibitor  

SciTech Connect

Low-dose {gamma} radiation stimulates expression of phenotypic characteristics in B16 melanoma cells which regulate metastatic potential. A transient increase in the expression of an integrin receptor ({alpha}{sub IIb}{beta}{sub 3}) was observed after exposure of B16 melanoma cells to 0.25 to 2.0 Gy of {gamma} radiation. This increased receptor expression resulted in enhanced adhesion of tumor cells to fibronectin in vitro and increased experimentally induced metastasis in vivo. In this report, we determined a role for the 12-lipoxygenase metabolite, 12-HETE, in radiation-enhanced metastasis. A significant increase in biosynthesis of 12-HETE in B16 melanoma cells was detected <5 min after exposure to 0.5 Gy {gamma} radiation. We then determined that radiation-enhanced expression of {alpha}{sub IIb}{beta}{sub 3} integrin and adhesion of B16 melanoma cells to fibronectin in vitro and metastasis in vivo were reduced by treatment of the cells with the lipoxygenase inhibitor NDGA prior to irradiation. These findings suggest that low-dose radiation, at levels comparable to those used in fractionated or hyperfractionated radiotherapy, increases the metastatic potential of surviving tumor cells via a rapid and transient alteration in lipoxygenase metabolism of arachidonic acid and surface expression of an integrin receptor. 30 refs., 5 figs., 1 tab.

Onoda, J.M.; Honn, K.V. [Wayne State Univ. School of Medicine, Detroit, MI (United States)]|[Gershenson Radiation Oncology Center, Detroit, MI (United States); Kantak, S.S.; Piechocki, M.P.; Awad, W.; Chea, R.; Liu, B. [Wayne State Univ. School of Medicine, Detroit, MI (United States)

1994-12-01

389

Activation of gamma delta T Cells in the Primary Immune Response to Mycobacterium tuberculosis  

Microsoft Academic Search

Although the immunologic role of T cells bearing the conventional alpha beta T cell receptor (TCR) has been well characterized, little is known about the function of the population of T cells bearing the gamma delta TCR. Therefore, the role of gamma delta T cells in the immune response the draining lymph nodes of mice immunized with MT was greatly

Eric M. Janis; Stefan H. E. Kaufmann; Ronald H. Schwartz; Drew M. Pardoll

1989-01-01

390

Effect of solvents on radiation-induced ionic graft polymerization. [Gamma radiation  

SciTech Connect

The influence of various solvents on radiation-induced cationic (grafting of vinyl-n-butyl ether onto polyethylene) and anionic (grafting of 2-methyl-5-vinylpyridine onto polyethylene) graft polymerization was studied. This ionic grafting was performed in thoroughly dried systems at room temperature. It was established that electron-acceptor solvents promote cationic grafting but that electron-donor solvents promote the anionic. A clear correlation between the donor number of solvents and grafting value by the anionic mechanism was shown. There was no correlation between dielectric constants and grafting values. The reaction orders, according to monomer concentraton by 2-methyl-5-vinylpyridine grafting in various solvents, were equal to approximately 1.5 and 2 for the radical and anionic mechanisms, respectively. The effect of solvents on radiation-induced ionic graft polymerization is discussed. The results of this study indicate the correct choice of solvents for radiation-induced ionic grafting.

Kabanov, V.Ya.; Aliev, R.E.; Sidorova, L.P.

1980-03-01

391

The Effects of Ionizing Radiation on Mammalian Cells.  

ERIC Educational Resources Information Center

|Discusses the effects of radiation on dividing cells and factors influencing these effects; also briefly reviews the radical mechanism for radiation damage. Emphasizes the importance of oxygen in radiation effects. (CS)|

Biaglow, John E.

1981-01-01

392

Alterations in damage processes in dense cancellous bone following gamma-radiation sterilization.  

PubMed

Structurally intact cancellous bone allograft is an attractive tissue form because its high porosity can provide space for delivery of osteogenic factors and also allows for more rapid and complete in-growth of host tissues. Gamma radiation sterilization is commonly used in cancellous bone allograft to prevent disease transmission. Commonly used doses of gamma radiation sterilization (25-35 kGy) have been shown to modify cortical bone post-yield properties and crack propagation but have not been associated with changes in cancellous bone material properties. The purpose of this study was to determine the effects of irradiation on the elastic and yield properties and microscopic tissue damage processes in dense cancellous bone. Cancellous bone specimens (13 control, 14 irradiated to 30 kGy) from bovine proximal tibiae were tested in compression to 1.3% apparent strain and examined for microscopic tissue damage. The yield strain in irradiated specimens (0.93+/-0.11%, mean+/-SD) did not differ from that in control specimens (0.90+/-0.11%, p=0.44). No differences in elastic modulus were observed between groups after accounting for differences in bone volume fraction. However, irradiated specimens showed greater residual strain (p=0.01), increased number of microfractures (p=0.02), and reduced amounts of cross-hatching type damage (p<0.01). Although gamma radiation sterilization at commonly used dosing (30 kGy) does not modify elastic or yield properties of dense cancellous bone, it does cause modifications in damage processes, resulting in increased permanent deformation following isolated overloading. PMID:20172526

Dux, S J; Ramsey, D; Chu, E H; Rimnac, C M; Hernandez, C J

2010-02-20

393

Thin films of In2O3/SiO as optical gamma radiation sensors  

NASA Astrophysics Data System (ADS)

This paper explores the use of mixed oxide materials such as In2O3 and SiO with various compositions in the form of thermally deposited thin films for gamma radiation dosimetry application. 137Cs radiation source with an activity of 370 kBq was used for exposing the samples to ?-radiation. The absorption spectra for as-deposited and ?-irradiated films were recorded using CARY 1E UV-Visible Spectrophotometer. The values of the optical band gap Eopt were obtained in the view of the Mott and Davis" theory. It was found that the optical properties of thin films were highly affected by composition and manufacturing conditions. For comparison, Eopt of as-deposited thin film with composition 75 wt.% of In2O3 and 25 wt.% of SiO was found to be 0.9 eV, whereas films with 50 wt.% of In2O3 and 50 wt.% of SiO have Eopt=1.15 eV, in all cases assuming indirect allowed transition. It was noted that Eopt decreased with the increase in radiation dose, i.e. the overall disorder of the system has increased. Thin films of In2O3 and SiO mixtures might be regarded as a cost-effective alternative to the existing commercially available radiation detectors.

Arshak, Khalil; Korostynska, Olga; Henry, John

2004-01-01

394

The use of gamma radiation for the elimination of Salmonella from frozen meat  

PubMed Central

The use of a gamma radiation process for the elimination of Salmonella from frozen meat is considered with particular reference to the treatment of boned-out horsemeat and kangaroo meat imported into the UK and intended for use as pet meat. Examination of dose/survival curves produced for several serotypes of Salmonella in frozen meat shows that a radiation dose of 0·6 Mrad. will reduce a population by at least a factor of 105. The influence on the radiation resistance of salmonellas of such factors as preirradiation growth in the meat and temperature during irradiation have been examined and considered. It is also demonstrated with both preinoculated and naturally contaminated meat that postirradiation storage in the frozen state does not lead to the revival of irradiated salmonellas. The properties of Salmonella survivors deliberately produced in meat using conditions of irradiation designed to simulate a commercial process are studied after six recycling treatments through the process. There were no important changes in characteristics normally used for identification of Salmonella but radiation resistance was lowered. Survivors grown in situ in meat after irradiation showed an abnormally long lag phase, and removal of competitive microflora in meat by the radiation treatment can influence the growth of salmonellas.

Ley, F. J.; Kennedy, T. S.; Kawashima, K.; Roberts, Diane; Hobbs, Betty C.

1970-01-01

395

Gamma radiation damage study of 0.18 µm process CMOS image sensors  

NASA Astrophysics Data System (ADS)

A 0.18 ?m process CMOS image sensor has recently been developed by e2v technologies plc. with a 0.5 megapixel imaging area consisting of 6 × 6 ?m 5T pixels. The sensor is able to provide high performance in a diverse range of applications including machine vision and medical imaging, offering good low-light performance at a video rate of up to 60 fps. The CMOS sensor has desirable characteristics which make it appealing for a number of space applications. Following on from previous tests of the radiation hardness of the image sensors to proton radiation, in which the increase in dark-current and appearance of bright and RTS pixels was quantified, the sensors have now been subjected to a dose of gamma radiation. Knowledge of the performance after irradiation is important to judge suitability for space applications and radiation sensitive medical imaging applications. This knowledge will also enable image correction to mitigate the effects and allow for future CMOS devices to be designed to improve upon the findings in this paper. One device was irradiated to destruction after 120 krad(Si) while biased, and four other devices were irradiated between 5 and 20 krad(Si) while biased. This paper explores the resulting radiation damage effects on the CMOS image sensor such as increased dark current, and a central brightening effect, and discusses the implications for use of the sensor in space applications.

Dryer, Ben; Holland, Andrew; Murray, N. J.; Jerram, Paul; Robbins, Mark; Burt, David

2010-07-01

396

A shuttle vector system for studying ionizing radiation-induced mutagenesis in mammalian cells.  

PubMed

A shuttle vector system was developed to quantitate and analyze ionizing radiation-induced mutation in mammalian host cells, COS-1 and CV-1. The shuttle vector pSV2-lacY, which was constructed to detect both point mutations and deletions, was irradiated in vitro with 60Co gamma rays before introduction into unirradiated host cells. The plasmid was then isolated and reintroduced into HB101 (lacY-) bacterial host cells for identification of mutated lacY marker genes. Gamma-irradiation produced a decrease of the survival (recovery) and an increase of mutation of the shuttle vector. The mutated shuttle vector molecules were examined for structural changes by means of restriction endonuclease digestion and agarose gel electrophoresis. A dose dependent increase was observed in the percentages of gross alteration events of total mutations in mammalian host. This system will be useful for studies of ionizing radiation-induced mutagenesis. PMID:8360857

Muraiso, C; Mudgett, J S; Matsudaira, H; Strniste, G F

1993-06-01

397

Optimizing Radiation Hard by Design SRAM Cells  

Microsoft Academic Search

Various radiation hardened by design SRAM cells are explored for their size, electrical performance, and total ionizing dose (TID) immunity. TID experiments using Co-60 testing on 130- and 90-nm transistors and SRAM arrays show that SRAM cells using two-edge transistors, NMOS access transistors, and NMOS reverse-body-bias effectively mitigate TID in both generations. This work experimentally demonstrates that commercial foundry (optimally

Lawrence T. Clark; Karl C. Mohr; Keith E. Holbert; Xiaoyin Yao; Jonathan Knudsen; Harshit Shah

2007-01-01

398

Radiation-induced cell death mechanisms  

Microsoft Academic Search

The main goal when treating malignancies with radiation therapy is to deprive tumor cells of their reproductive potential.\\u000a One approach to achieve this is by inducing tumor cell apoptosis. Accumulating evidences suggest that induction of apoptosis\\u000a alone is insufficient to account for the therapeutic effect of radiotherapy. It has become obvious in the last few years that\\u000a inhibition of the

David Eriksson; Torgny Stigbrand

2010-01-01

399

Effects of alpha and gamma radiation on glass reaction in an unsaturated environment  

SciTech Connect

Radiation may effect the long-term performance of glass in an unsaturated repository site by interacting with air, water vapor, or liquid water. The present study examines (1) the effects of alpha or gamma irradiation in a water vapor environment, and (2) the influence of radiolytic products on glass reaction. Results indicate that nitric and organic acids form in an irradiated water vapor environment and are dissolved in thin films of condensed water. Glass samples exposed to these conditions react faster and have a different assemblage of secondary phases than glasses exposed to nonirradiated water vapor environments. 23 refs., 4 figs., 2 tabs.

Wronkiewicz, D.J.; Young, J.E.; Bates, J.K.

1990-12-31

400

Determination of canine dose conversion factors in mixed neutron and gamma radiation fields. Technical report  

SciTech Connect

The primary objective of mixed-field neutron/gamma radiation dosimetry in canine irradiation experiments conducted at the Armed Forces Radiobiology Research Institute (AFRRI) is to determine the absorbed midline tissue dose (MLT) at the region of interest in the canine. A dose conversion factor (DCF) can be applied to free-in-air (FIA) dose measurements to estimate the MLT doses to canines. This report is a summary of the measured DCFs that were used to determine the MLT doses in canines at AFRRI from 1979 to 1992.

Torres, B.A.; Bhatt, R.C.; Myska, J.C.; Holland, B.K.

1996-07-01

401

Effect of gamma radiation on low density polyethylene (LDPE) films: Optical, dielectric and FTIR studies  

NASA Astrophysics Data System (ADS)

The low density polyethylene (LDPE) films were irradiated with gamma radiation in the dose range varied from 20 to 400 kGy. The induced changes in the chemical structure and dielectric properties for the irradiated films were investigated. The structure modifications: crystallinity as well as possible molecular changes of the polymer were recognized using Fourier Transform Infrared Spectroscopy (FTIR). The optical results were determined from transmission, reflection and absorption spectra for these films. The dielectric properties of these films were calculated using optical methods. Result indicates small variation in crystallinity which could be increased or decreased depending on the relative importance of the structural and chemical changes.

Moez, A. Abdel; Aly, S. S.; Elshaer, Y. H.

402

Effect of gamma radiation on low density polyethylene (LDPE) films: optical, dielectric and FTIR studies.  

PubMed

The low density polyethylene (LDPE) films were irradiated with gamma radiation in the dose range varied from 20 to 400 kGy. The induced changes in the chemical structure and dielectric properties for the irradiated films were investigated. The structure modifications: crystallinity as well as possible molecular changes of the polymer were recognized using Fourier Transform Infrared Spectroscopy (FTIR). The optical results were determined from transmission, reflection and absorption spectra for these films. The dielectric properties of these films were calculated using optical methods. Result indicates small variation in crystallinity which could be increased or decreased depending on the relative importance of the structural and chemical changes. PMID:22481176

Moez, A Abdel; Aly, S S; Elshaer, Y H

2012-02-18

403

Inheritance of induction radiation sensitivity of space flight environments and gamma-radiation on rice  

Microsoft Academic Search

There are many factors affecting living things during space flight, such as microgravity, cosmic radiation, etc. A large number of plant mutants have been obtained after space flight on satellite in China in the last decade and some commercial crop varieties were released. However, little consideration has so far been given to the genetic mechanisms underlying sensitivity of plant seeds

J. Xu; J. Wang; L. Wei; Z. Li; Y. Sun

2004-01-01

404

Gene transfer studies of T cell receptor-gamma delta recognition. Specificity for staphylococcal enterotoxin A is conveyed by V gamma 9 alone.  

PubMed

gamma delta T cells bearing the V gamma 9 gene segment have been shown to recognize staphylococcal enterotoxin A (SEA) and a range of other Ags including mycobacterial Ags. We have established an experimental system to analyze the recognition properties of human TCR-gamma delta on a molecular level by transferring the receptor from its original T cell into a Jurkat T cell host that does not express an endogenous TCR. Three groups of transfectants that express the same delta-chain, V delta 1, but different gamma-chains (V gamma 9-J2-C gamma 2, V gamma 3-J2-C gamma 2, and V gamma 9-JP-C gamma 1) together with the endogenous CD3 were obtained. The transfectant T cells each expressing different gamma delta receptors all produced IL-2 after stimulation with plastic bound anti-CD3 Ab, but only those expressing V gamma 9 responded to stimulation with SEA in the presence of an autologous lymphoblastoid B cell line. In addition, transfectants that expressed V delta 2 combined with V gamma 9 could also respond to SEA. These results indicate that the V gamma 9 portion of the receptor, independent of the J region and C region or the delta-chain, is responsible for recognizing SEA. PMID:8144918

Loh, E Y; Wang, M; Bartkowiak, J; Wiaderkiewicz, R; Hyjek, E; Wang, Z; Kozbor, D

1994-04-01

405

Enhanced Beta-Gamma Coincidence Counting Gas Cell  

SciTech Connect

The Automated Radioxenon Sampler/Analyzer (ARSA) uses a highly compact, high efficiency beta-gamma coincidence detector to detect 133Xe, 131mXe, 133mXe and 135Xe for treaty monitoring and environmental sampling. This system has shown itself to be reliable and robust in several field exercises [1, 2]. However, from a maintenance and quality assurance/quality control (QA/QC) standpoint it suffers from a very detailed photo-multiplier-tube gain matching regime. In an effort to upgrade and simplify the current beta-gamma coincident detector, PNNL has developed a simplified but equally effective well-type detector. Initial comparison between three different well detectors has been performed. Along with the well gamma-ray detectors, a new plastic scintillation gas cell was constructed. The spectral resolution and efficiency obtained from this new design has been demonstrated to be as good as or better than the original ARSA design with greatly improved calibration and maintenance characteristics. The ARSA detector and the well-detector design and effectiveness for xenon detection will be discussed.

McIntyre, Justin I.; Carman, April J.; Aalseth, Craig E.; Hayes, James C.; Heimbigner, Tom R.; Hossbach, Todd W.; Hubbard, Charles W.; Litke, Kevin E.; Miley, Harry S.; Morris, Scott J.; Ripplinger, Michael D.; Suarez, Reynold

2005-10-01

406

Search for radiation signals from electrolytic cells  

NASA Astrophysics Data System (ADS)

There have been many reports of observed heat generated above joule heating from electrolytic systems. A high current density electrolytic system was designed to test for radiation signals other than IR from an electrolytic process. The system employs current densities on the order of 100 Amps/cm^2 and uses a large Beryllium sulfate heavy water neutron moderator/reflector. The search is planned to look at the visual spectrum, neutron emission, gamma emission, alpha emission and electrical signals in the current flow to the system. The electrolysis is preformed with a heavy water solution, and materials with large neutron cross sections will be employed at the electrodes. Results of the on-going investigation will be reported.

Cravens, Dennis J.

2005-03-01

407

[Mechanism of injury of air-dry pea seeds under the influence of low doses of gamma-radiation].  

PubMed

The aim of this work was to determine which processes in air-dry seeds result in bimodal changes of the pea seed quality under the influence of low doses of gamma-radiation. Pea seeds (cv. "Nemchinovsky-85", harvest 2006, 82% germination persentage) were exposed to gamma-radiation at doses of 3, 10 and 100 Gy The germination percentage decreased to 45% four days after irradiation at the dose of 3 Gy, rised up to 87% at doses of 10 Gy, while the dose of 100 Gy killed the most part of seeds. Seed fractions differing in quality were selected using the metod of Room temperature phosphorecsence (RTP): strong seed frasction I from non-irradiated seeds; weak seed fraction II from the seeds irradiated at a dose of 3 Gy; dead seeds from the seeds irradiated at a dose of 100 Gy. ThermoChemiLuminecnsece (TCL) of seed powders and cotyledons was used. It was shown that the increase of the TCL level in the temperature range from 50 to 110 degreesC was associated with the lipid peroxidation products. The TCL level of seeds subjected to gamma-irradiation at a dose of 3 Gy was similar to that of non-irradiated seeds in the temperature range 50 to 100 degreesC. Therefore, lipid peroxidation was not the cause of the abnormal seedling appearance. The TCL level within this temperature range was increased only in seeds subjected to y-irradiation at a dose of 100 Gy. The TCL level at 150 degreesC was in proportion with the exogenous glucose amount. The increased TCL level of seeds subjected to y-irradiation at a dose of 3 Gy at 150 degreesC resulted from the increase of the glucose content. This means that the transition from the fraction of strong seeds into the fraction of weak ones was the result of the activation of hydrolysis processes. Decrease in the water content of seeds testified to utilization of bound water in this process. The decrease of the glucose content in the "improved" seeds subjected to gamma-irradiation at a dose of 10 Gy most probably indicates the participation of glucose in the amino carbonyl reaction. The latter could be the reason for the increased water content in the "improved" seeds and a decreased water permeability of cell membranes. PMID:22568014

Veselova, T V; Veselovski?, V A

408

Modulation of radiation-induced apoptosis and G{sub 2}/M block in murine T-lymphoma cells  

SciTech Connect

Radiation-induced apoptosis in lymphocyte-derived cell lines is characterized by endonucleolytic cleavage of cellular DNA within hours after radiation exposure. We have studied this phenomenon qualitatively (DNA gel electrophoresis) and quantitatively (diphenylamine reagent assay) in murine EL4 T-lymphoma cells exposed to {sup 137}Cs {gamma} irradiation. Fragmentation was discernible within 18-24 h after exposure. It increased with time and dose and reached a plateau after 8 Gy of {gamma} radiation. We studied the effect of several pharmacological agents on the radiation-induced G{sub 2}/M block and DNA fragmentation. The agents which reduced the radiation-induced G{sub 2}/M-phase arrest (caffeine, theobromine, theophylline and 2-aminopurine) enhanced the degree of DNA fragmentation at 24 h. In contrast, the agents which sustained the radiation-induced G{sub 2}/M-phase arrest (TPA, DBcAMP, IBMX and 3-aminobenzamide) inhibited the DNA fragmentation at 24 h. These studies on EL4 lymphoma cells are consistent with the hypothesis that cells with radiation-induced genetic damage are eliminated by apoptosis subsequent to a G{sub 2}/M block. Furthermore, it may be possible to modulate the process of radiation-induced apoptosis in lymphoma cells with pharmacological agents that modify the radiation-induced G{sub 2}/M block, and to use this effect in the treatment of patients with malignant disease. 59 refs., 7 figs.

Palayoor, S.T.; Macklis, R.M.; Bump, E.A.; Coleman, C.N. [Harvard Medical School, Boston, MA (United States)

1995-03-01

409

Properties of gamma-glutamyl transpeptidase in squamous cell carcinoma.  

PubMed

gamma-Glutamyl transpeptidase (GGT) was extracted from squamous cell carcinoma tissues of human skin (SCC) by Triton X-100 and bromelain treatment, and some of its biochemical properties were compared with those of GGT extracted from eccrine gland-rich tissue and normal kidney. GGT activity significantly increased in SCC, but there was no definitive differences in enzymological properties between GGT of SCC and normal tissue enzyme. However, GGT of SCC was distinguishable from those of normal tissues by isoelectric point, electrophoretic mobility, and sensitivity to neuraminidase treatment. These results indicate that GGT of SCC has some variant properties which may be related to skin carcinogenesis. PMID:8097748

Takami, Y; Chiba, M; Takahashi, M

1993-01-01

410

Radiation-induced oxidative degradation of poly(vinyl chloride). [Gamma radiation  

SciTech Connect

Gas evolution and oxygen consumption in the ..gamma..-irradiation of PVC were studied. The gas evolution and the oxidative degradation are retarded by the presence of plasticizers and stabilizers. The G(HCl) and G(H/sub 2/) are 8 and 0.24 for the irradiation of pure PVC under vacuum and 0.02 and 0.14 for that of plasticized PVC, respectively. Gas evolution increases in the presence of oxygen, specially for the pure PVC. The G(-O/sub 2/) values for the pure and plasticized PVC are 30 and 12, respectively. The dependence of gas evolution and oxygen consumption on the oxygen pressure is more pronounced for the plasticized PVC than pure PVC because the oxygen diffusion is controlled.

Hegazy, E.S.A.; Seguchi, T.; Machi, S.

1981-09-01

411

Somatic aberration induction in Tradescantia occidentalis by neutrons, x- and gamma-radiations. II. Biological results, r.b.e. and o.e.r.  

PubMed

Biological results, including statistical features, are described for the irradiation of Tradescantia occidentalis with 250 kVp X-rays, cobalt-60 gamma-radiation and monoenergetic neutrons with energies between 0-08 and 15 MeV. The effect studied was that of the induction of pink sectors in the otherwise blue staminal hairs of the flowers at low doses of radiation. Statistical aspects of the results suggest that a fraction of the asynchronous cell population in the hairs is very sensitive to neutron radiation, but not necessarily to lower LET radiations. All the results were fitted by a least-squares method by polynomials of different degrees. Best fits to X- and gamma-ray data were provided by second-degree polynomials, and to the neutron data by either second- or third-degree polynomials. Limiting r.b.e. and o.e.r. values at low doses are derived. Some computed microdosimetric parameters are presented in comparison with the r.b.e. values. It is concluded that the effect studied is complex and may not provide a critical test of bio-physical theories of radiation effects. PMID:1084866

Dennis, J A

1976-04-01

412

The effect of high dose rate transient gamma radiation on high-energy optical fibers  

NASA Astrophysics Data System (ADS)

High power laser systems have a number of uses in a variety of scientific and defense applications, for example laser induced breakdown spectroscopy (LIBS) or laser-triggered switches. In general, high power optical fibers are used to deliver the laser energy from the source to the target in preference to free space beams. In certain cases, such as nuclear reactors, these optical systems are expected to operate in ionizing radiation environments. In this paper, a variety of modern, currently available commercial off-the-shelf (COTS) optical fiber designs have been assessed for successful operation in the transient gamma radiation environment produced by the HERMES III accelerator at Sandia National Laboratories, USA. The performance of these fibers was evaluated for high (~1 MW) and low (<1 W) optical power transmission during high dose rate, high total dose gamma irradiation. A significant reduction in low optical power transmission to 32% of maximum was observed for low OH- content fibers, and 35% of maximum for high OH- fibers. The high OH- fibers were observed to recover to 80% transmission within 1 ?s and 100% transmission within 1 ms. High optical power transmission losses followed generally similar trends to the low optical power transmission losses, though evidence for an optical power dependent recovery was observed. For 10-20 mJ, 15 ns laser pulses, around 46% was transmitted coincident with the radiation pulse, recovering to 70% transmission within 40 ns of the radiation pulse. All fibers were observed to completely recover within a few minutes for high optical powers. High optical power densities in excess of 1 GW/cm2 were successfully transmitted during the period of highest loss without any observed damage to the optical fibers.

Akinci, A.; Bowden, M. D.; Cheeseman, M. C.; Knowles, S. L.; Meister, D. C.; Pecak, S. N.; Simmons Potter, K.

2009-08-01

413

Radiation grafting of methyl methacrylate monomer on natural rubber latex. [Gamma radiation  

SciTech Connect

A method of radiation grafting of methyl methacrylate (MMA) monomer on natural rubber (NR) latex has been studied. The irradiation dose in radiation emulsion polymerization of MMA monomer was lower compared to the irradiation dose for grafting of MMA monomer on NR latex, in order to obtain the same degree of conversion. This is due to the size of the rubber particles which are quite large and, hence, not sufficient to ensure an ideal emulsion polymerization. The irradiation dose for radiation grafting of MMA monomer on latex was around 300 krad to obtain a 75% degree of conversion. However, this irradiation dose was lower compared to the irradiation dose for bulk polymerization of MMA momomer, in order to obtain the same degree of conversion. This is due to the gel effect in the viscous media. Radiation grafting of MMA monomer on NR latex does not influence the pH of the latex, but influences the viscosity significantly. The viscosity of the NR latex increased with an increase in irradiation dose, due to the increase of the total solid content in the latex. The MMA monomer converted to P-MMA in NR latex was largely grafted on the NR, or at least insoluble in a solvent for P-MMA, such as acetone or toluene. The hardness of the pure gum vulcanizate increased with an increase in the degree of grafting or P-MMA content, but the other physical properties, such as tensile strength, modulus, elongation at break, and thermal stability, were not greatly influenced by the degree of grafting. 9 references, 3 figures, 5 tables.

Sundardi, F.; Kadariah, S.

1984-05-01

414

Radiation induced genomic instability in bystander cells  

NASA Astrophysics Data System (ADS)

There is considerable evidence that exposure to ionizing radiation may induce a heritable genomic instability that leads to a persisting increased frequency of genetic and functional changes in the non-irradiated progeny of a wide variety of irradiated cells Genomic instability is measured as delayed expressions in chromosomal alterations micronucleus formation gene mutations and decreased plating efficiency During the last decade numerous studies have shown that radiation could induce bystander effect in non-irradiated neighboring cells similar endpoints have also been used in genomic instability studies Both genomic instability and the bystander effect are phenomena that result in a paradigm shift in our understanding of radiation biology In the past it seemed reasonable to assume that the production of single- and double-strand DNA breaks are due to direct energy deposition of energy by a charged particle to the nucleus It turns out that biology is not quite that simple Using the Columbia University charged particle microbeam and the highly sensitive human hamster hybrid AL cell mutagenic assay we irradiated 10 of the cells with a lethal dose of 30 alpha particles through the nucleus After overnight incubation the remaining viable bystander cells were replated in dishes for colony formation Clonal isolates were expanded and cultured for 6 consecutive weeks to assess plating efficiency and mutation frequency Preliminary results indicated that there was no significant decrease in plating efficiency among the bystander colonies when compared with

Zhou, H.; Gu, S.; Randers-Pehrson, G.; Hei, T.

415

The repair of gamma-radiation-induced DNA damage is inhibited by microcystin-LR, the PP1 and PP2A phosphatase inhibitor.  

PubMed

The genotoxic activity of microcystin-LR (MC-LR) is a matter of debate. MC-LR is known to be a phosphatase inhibitor and it may be expected that it is involved in the regulation of the activity of DNA-dependent protein kinase (DNA-PK), the key enzyme involved in the repair of radiation-induced DNA damage. We studied the effect of MC-LR on the repair capacity of radiation-induced DNA damage in human lymphocytes and human glioblastoma cell lines MO59J and MO59K. A dose of 0.5 microg/ml of MC-LR was chosen because it induced very little early apoptosis which gives no false positive results in the comet assay. Human lymphocytes in G0-phase of the cell cycle were pre-treated with MC-LR for 3 h and irradiated with 2 Gy of gamma radiation. The kinetics of DNA repair was assessed by the comet assay. In addition the frequencies of chromosomal aberrations were analysed. The pre-treatment with MC-LR inhibited the repair of radiation-induced damage and lead to enhanced frequencies of chromosomal aberrations including dicentric chromosomes. The results of a split-dose experiment, where cells were exposed to two 1.5 Gy doses of radiation separated by 3 h with or without MC-LR, confirmed that the toxin increased the frequency of dicentric chromosomes. We also determined the effect of MC-LR and ionizing radiation on the frequency of gamma-H2AX foci. The pre-treatment with MC-LR resulted in reduced numbers of gamma-H2AX foci in irradiated cells. In order to elucidate the impact of MC-LR on DNA-PK we examined the kinetics of DNA repair in human glioblastoma MO59J and MO59K cells. Both cell lines were exposed to 10 Gy of X-rays and DNA repair was analysed by the comet assay. A strong inhibitory effect was observed in the MO59K but not in the MO59J cells. These results indicate that DNA-PK might be involved in DNA repair inhibition by MC-LR. PMID:16434448

Lankoff, A; Bialczyk, J; Dziga, D; Carmichael, W W; Gradzka, I; Lisowska, H; Kuszewski, T; Gozdz, S; Piorun, I; Wojcik, A

2006-01-24

416

Radiation Induced Bystander Effects in Human Lymphoblastoid Cells.  

National Technical Information Service (NTIS)

It is well accepted that cells, in response to radiation, may release transmissible factors. These transmissible factors, clastogenic factors, have been reported to induce genomic instability in cells that have not been directly exposed to radiation. We h...

T. M. Segura D. Wilkinson L. Prud'honne-Lalonde E. M. Thorleifson S. Lachapelle

2003-01-01

417

Gamma\\/delta T cells and human skin reactivity to heavy metals  

Microsoft Academic Search

Gamma\\/delta T cells may act as a first line of defence and respond to stress signals from the surrounding tissue. In the present investigation the occurrence of gamma\\/delta T cells was studied in the human skin after application of heavy metal salts by a routine epicutaneous patch-testing procedure. Gamma\\/delta cells were not found in normal skin. They were observed in

K. Nordlind; S. Lidén

1995-01-01

418

Increase in bacteriophage radiation resistance as a result of enhanced expression of stress systems in host cells  

SciTech Connect

By means of polyacrylamide gel electrophoresis (PAGE) of proteins from radiation-resistant Gam{sup r} mutants of Escherichia coli, it was shown that induction and elimination of RecA protein in these mutants are kinetically more rapid than in wild type cells, and heat-shock proteins (HSP) are hyperproduced even at a normal temperature (32{degrees}C). {gamma}- and UV-irradiated bacteriophages were used to study the results of simultaneous enhanced expression of two stress repair systems. Radiation-resistant mutants are similar to wild type cells in their ability to reactivate phages {Lambda}cI, {phi}80 vir, and T4D inactivated by {gamma}-rays and UV-light. W-reactivation of {gamma}-irradiated phages {Lambda} and {phi}80 is respectively 1.5 and 1.2 times higher in Gam{sup r} cells in which maximal W-reactivation was observed at wide range of doses (from 300 to 2000 Gy), whereas in wild type cells the peak C of W-reactivation was registered at doses of 400 to 450 Gy. The phage {Lambda}, {gamma}-irradiated upon adsorption on the cells of a radiation-resistant mutant, was two times more resistant to {gamma}-rays (DMF = 2 at LD{sub 10}) than when irradiated upon adsorption on wild type cells. Postirradiation degradation of the phage {Lambda} DNA, when irradiated within Gam{sup r} cells, was significantly lower than in wild type cells, and preirradiation of the cells decreased phage DNA degradation (12% in Gam{sup r} cells and 30% in wild-type cells). The role of an increased HSP level and expression of SOS-regulon in radiation resistance and possible interaction of stress systems in bacterial cells are discussed. 18 refs., 6 figs.

Verbenko, V.N.; Kalinin, V.L. [Konstantinov Inst. of Nuclear Physics, Gatchina (Russian Federation)

1995-12-01

419

Degradation of chitosan and sodium alginate by gamma radiation, sonochemical and ultraviolet methods  

NASA Astrophysics Data System (ADS)

Three degradation methods: ultrasonic, ultraviolet and gamma irradiation were applied to sodium alginate and chitosan in aqueous solutions. The changes in molecular weight were monitored by GPC measurements. It has been found that from the energetic point of view the most effective method for both polymers is gamma radiation method with a yield of scission G=0.55×10mol/J for 1% alginate and G=3.53×10mol/J for 1% chitosan. However, considering the reaction time, the ultraviolet method is the most effective, with reaction rate constant k=0.52h for alginate and 1.6 h-1 for chitosan. Based on FTIR spectra, taken before and after degradation it was revealed, that degradation undergoes by the breakage of the glycosidic bonds of polymers. UV spectroscopy showed absorption peak at 265 nm for alginate, and two peaks at the range of 250 280 nm for chitosan. UV spectroscopy for ultrasonic is not revealed and any peak suggesting ultrasonic degradation undergoes different mechanism than ultraviolet and gamma degradations, probably mechanical one.

Wasikiewicz, Jaroslaw M.; Yoshii, Fumio; Nagasawa, Naotsugu; Wach, Radoslaw A.; Mitomo, Hiroshi

2005-08-01

420

Search for ultra-high energy radiation from gamma-ray bursts  

NASA Astrophysics Data System (ADS)

A recent class of models suggests that some gamma-ray bursters may produce ultra-high-energy (greater than or equal to 100 TeV) photons. Using data from the CYGNUS array, we have searched for evidence of emission of ultra-high-energy radiation coincident with gamma-ray bursts observed either by the third Interplanetary Network of satellites or by the Burst and Transient Source Experiment (BATSE) instrument on the Compton Gamma-Ray Observatory. No statistically significant excess was found for six bursts whose locations were accurately determined by the Network, or for any point in the sky within 2 sigma of the BATSE location coordinates of 52 additional bursts. Flux upper limits depend greatly on the zenith angles of the bursts, but typical limits above 100 TeV are approximately 4 x 10-10/sq cm(s). The flux upper limits for three of the bursts imply that the observed spectrum softens between 2 MeV and approximately 100 TeV. If the production spectrum does not soften between these energies, the bursts must have a cosmological origin.

Alexandreas, D. E.; Allen, G. E.; Berley, D.; Biller, S.; Burman, R. L.; Cavalli-Sforza, M.; Chang, C. Y.; Chen, M. L.; Chumney, P.; Coyne, D.; Dion, C.; Dion, G. M.; Dorfan, D.; Ellsworth, R. W.; Goodman, J. A.; Haines, T. J.; Harmon, M.; Hoffman, C. M.; Kelley, L.; Klein, S.; Nagle, D. E.; Schaller, S. C.; Schmidt, D. M.; Schnee, R.; Shoup, A.; Sinnis, C.; Stark, M. J.; Weeks, D. D.; Williams, D. A.; Wu, J.-P.; Yang, T.; Yodh, G. B.; Zhang, W.

1994-05-01

421

Correlation between gamma radiation levels and soil radium concentrations at the Edgemont uranium mill site  

SciTech Connect

The Tennessee Valley Authority's uranium mill in Edgemont, South Dakota, is being decommissioned. Approximately 4 million tons of contaminated tailings, building equipment, and contaminated soil and debris on the mill site will be removed to the disposal site located approximately 3 kilometers to the southeast. To minimize recontamination of cleaned areas, tailings removal will progress from the northwest corner to the southeast corner of the mill site. As specific areas are cleaned, surveys will be conducted to determine if the concentrations of radium-226 in soil are within the limits outlined in 40 CFR, Part 192. Conformance with the criteria will be demonstrated by a gamma survey of the area employing the differential, or delta-measurement, technique. This technique involves fitting the detector with a base and a receptacle for a removable high-density filter. By making measurements with and without the filter in place, a gamma radiation level proportional to the radium-226 concentration in soil can be determined. This paper describes the results obtained in the development of the correlation between the gamma survey measurements and the soil radium concentrations.

Wallace, R.G.; Reed, R.P.; Polehn, J.L.; Wilson, G.T.

1985-01-01

422

Resistance of a cultured fish cell line (CAF-MM1) to. gamma. irradiation  

SciTech Connect

Fish are generally more resistant to whole-body ionizing radiation than mammals. To study the radiosensitivity of fish in vitro, CAF-MM1 cells derived from the fin of the goldfish, Carassius auratus, were used. The survival parameters of CAF-MM1 obtained after ..gamma.. irradiation at 26/sup 0/C were 325 rad for D/sub o/, 975 rad for Dq, and 15 for n. No mammalian cell line with such a low sensitivity in the presence of O/sub 2/ has been reported. It was found that the large initial shoulder of the survival curve was paralleled by substantial repair of sublethal damage as evidenced by split-dose experiments. This low sensitivity to ..gamma.. irradiation did not change upon the administration of caffeine or postirradiation illumination, although these treatments were effective after uv irradiation. The decrease in the mitotic index in CAF-MM1 occurred immediately after irradiation, and it recovered within a very short time. This indicated that the duration of G2 arrest was shorter than that observed in mammalian cells. The data also suggest that the resistance of fish to whole-body irradiation is attributable to resistance at the cellular level.

Mitani, H.; Etoh, H.; Egami, N.

1982-02-01

423

Lack of protection by carotenes against gamma-radiation damage in Phycomyces  

Microsoft Academic Search

Carotenes could protect cells from radiation damage by chemically quenching the free radicals and the activated chemical species\\u000a originated by the exposure. We tested this hypothesis with strains of the zygomycete Phycomyces blakesleeanus that contained different carotenes (phytoene, lycopene, ?-carotene) or different concentrations of ?-carotene. Pairs of strains\\u000a were cultured together, exposed to a maximum of 73 Gy ?-radiation from

V. Martín-Rojas; A. Gómez-Puerto; E. Cerdá-Olmedo

1996-01-01

424

THE EFFECT OF IONIZING RADIATION UPON $gamma$-AlâOâ AS A CATALYST FOR Hâ-Dâ EXCHANGE  

Microsoft Academic Search

Relatively small doses of gamma rays at -78 deg C have been found to ; enhance the Hâ--Dâ exchange activity of gamma AlâOâ. ; The enhancement by radiation depends upon the presence of a catalyst poison, H\\/; sub 2\\/O, Hâ or CâHâ and in the case of HâO is a function ; of the extent of poisoning, being greatest for

H. W. Kohn; E. H. Taylor

1959-01-01

425

The Appearance of Primeval Galaxies in X- and gamma-Ray Regions and Their Contributions to the Background Radiation  

Microsoft Academic Search

By studying the chemical evolution of a galaxy, its optical, infra-red, X- and gamma-ray luminosities and the integrated background radiation due to these galaxies in their early flashing era are calculated. We conclude that these primeval galaxies are more detectable in X- and gamma-ray regions than in the infra-red region. In 1 keV and 100 MeV regions, much part of

Y. Tanaka; S. Ikeuchi

1979-01-01

426

EFFECT OF $gamma$RADIATION ON THE SHAPE OF MOSSBAUER RESONANCE ABSORPTION SPECTRA IN TIN-ORGANIC COMPOUNDS  

Microsoft Academic Search

The effect of gamma radiation on the shape of the spectra of Mossbauer ; resonance absorption of 23.8-kev gamma quanta in tin-organic compounds is ; investigated. The change in the spectrum for the compound (CâHâ)\\/sub ; 2\\/ SnSOâ corresponds to splitting of the compound and formation of the ; compounds SnSOâ and possibly (CâHâ)â SnSOâ (upon ; irra diation in

A. Yu. Aleksandrov; N. N. Delyagin; K. P. Mitrofanov; L. S. Polak; V. S. Shpinel

1962-01-01

427

EGRET detection of high-energy gamma radiation from the OVV quasar 3C 454.3  

Microsoft Academic Search

High-energy gamma radiation has been observed from the optically violent variable quasar 3C 454.3 (PKS 2251 + 158) by the Energetic Gamma-Ray Experiment Telescope on the Compton Observatory. During the 1992 January-February observation, the emission showed a power-law photon spectrum with an exponent of -2.18 +\\/- 0.08. The flux density (greater than 100 MeV) was observed to vary within the

R. C. Hartman; D. L. Bertsch; B. L. Dingus; C. E. Fichtel; S. D. Hunter; G. Kanbach; D. A. Kniffen; Y. C. Lin; J. R. Mattox; H. A. Mayer-Hasselwander; P. F. Michelson; C. von Montigny; P. L. Nolan; B. G. Piner; E. Schneid; P. Sreekumar; D. J. Thompson

1993-01-01

428

Influence of gamma radiation on the gel rigidity index and binding capability of gelatin  

SciTech Connect

Changes in the rigidity indices of gelatin gel before and after gamma irradiation were characterized by dynamic mechanical testing, and the significance of these changes on the strength of granules was evaluated. Results illustrate the difficulty of obtaining reproducible values for gels containing less than 20% gelatin. However, rigidity indices for gels with a gelatin content of 20% and higher are consistent and may provide a useful controlling factor for preparation of gelatins of more precise specifications. The data indicate that rigidity degradation kinetics of several concentrations of gelatin gel at different radiation doses are complex, showing both increasing and decreasing rates. These findings strongly suggest that doses of less than 2.0 Mrad of gamma radiation should be used in order to obtain gelatins of acceptable quality for pharmaceutical applications. The crushing strength of granules of lactose powder granulated with irradiated gelatin reveals that the binding capability of such gelatin is significantly reduced. The results obtained for various size fractions and granule hardnesses containing different binder concentrations also suggest that particle size influences the granule strength to a lesser extent than does binder concentration and its consistency.

Fassihi, A.R.; Parker, M.S.

1988-10-01

429

Single-source gamma radiation procedures for improved calibration and measurements in porous media  

SciTech Connect

When dual-energy gamma radiation systems are employed for measurements in porous media, count rates from both sources are often used to compute parameter values. However, for sever