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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Annual Report 2014 - Institute of Resource Ecology

10 March 2015 (has links) (PDF)
The Institute of Resource Ecology (IRE) is one of the eight institutes of the Helmholtz-Zentrum Dresden – Rossendorf (HZDR). The research activities are mainly integrated into the program “Nuclear Waste Management, Safety and Radiation Research (NUSAFE)” of the Helmholtz Association (HGF) and focused on the topics “Safety of Nuclear Waste Disposal” and “Safety Research for Nuclear Reactors”. Additionally, various activities have been started investigating chemical and environmental aspects of processing and recycling of strategic metals, namely rare earth elements. These activities are located in the HGF program “Energy Efficiency, Materials and Resources (EMR)”. Both programs, and therefore all work which is done at IRE, belong to the research sector “Energy” of the HGF. The research objectives are the protection of humans and the environment from hazards caused by pollutants resulting from technical processes that produce energy and raw materials. Treating technology and ecology as a unity is the major scientific challenge in assuring the safety of technical processes and gaining their public acceptance. We investigate the ecological risks exerted by radioactive and nonradioactive metals in the context of nuclear waste disposal, the production of energy in nuclear power plants, and in processes along the value chain of metalliferous raw materials. A common goal is to generate better understanding about the dominating processes essential for metal mobilization and immobilization on the molecular level by using advanced spectroscopic methods. This in turn enables us to assess the macroscopic phenomena, including models, codes, and data for predictive calculations, which determine the transport and distribution of contaminants in the environment.
2

A STUDY OF RADIATION-INDUCED PULMONARY FIBROSIS (RIPF) IN MOUSE MODELS USING DIAGNOSTIC IMAGING

Daniel R McIlrath (8781065) 29 April 2020 (has links)
<p>Radiation-induced lung injury (RILI) is a common condition in the setting of lung and breast cancer. Often, patients who suffer from RILI experience pneumonitis and pulmonary fibrosis months after treatment. These pathologies have commonly been modeled using mice and observing their deterioration until mortality and quantifying pathology on histological sections.<b> </b></p> <p>With this study, we used a longitudinal microCT and a 7T MRI to characterize male C57Bl/6 mice irradiated with a single dose of 20 Gy to the whole thoracic area delivered by an X-Rad cabinent irradiator. CT was performed with a respiratory gating sequence at 2 week timepoints to construct an RIPF model. The fraction of RIPF to total lung volume was calculated at each time point from images, and the data was anaylzed using one-way ANOVA Welch and Dunnett’s T3 multiple comparisons tests. Tidal lung volumes were also calculated and anlyazed in a simlar manner. Mice were then imaged using MRI and CT at 0, 5, and 8 week timepoints to compare results. These results were analyzed for comparison (ANOVA and Dunnett’s T3) and correlation (Pearson’s r) with each other. Histology was later performed using H&E and Trichrome stains to provide ex-vivo verification of pathology.<b> </b>At the 10-12 week time point ( ) significant RIPF formed. Weeks proceeding showed increased significance until the 22+ week timepoint, which showed less statistical significance ( ) due to increased variance at this timepoint. Dunnett’s T3 test showed no significant differences between tidal lung volumes over time. Tests also showed no significant differences between CT and MRI results with a correlation coefficient of .<b> </b>Early in the study, problems arose when pre-marture mortality was occurring to a significant portion of our subjects. Analysis later showed issues during irradiation that resulted in significant dose being absorbed by the stomach. Adjusting our shiedling lead to increased early survival of our subjects enabling us to contine our study. Significant RIPF development was not significant until 10-12 weeks post-irradiation, then RIPF became more severe at proceeding timepoints. Tidal lung volume showed no significant deviation over the development of RIPF. This result is most likely affected by the variation of results at later timepoints, since several mice with severe RIPF were significantly hindered in their ability to breathe during the study. MRI results showed close correlation with CT results and prodcued similar values at early timepoints. However, noticeable differences were seen at later timepoints when significant RIPF developed ( ). <b></b></p>
3

Annual Report 2016 Institute of Resource Ecology

21 March 2017 (has links) (PDF)
The Institute of Resource Ecology (IRE) is one of the eight institutes of the Helmholtz-Zentrum Dresden – Rossendorf (HZDR). The research activities are mainly integrated into the program “Nuclear Waste Management, Safety and Radiation Research (NUSAFE)” of the Helmholtz Association (HGF) and focused on the topics “Safety of Nuclear Waste Disposal” and “Safety Research for Nuclear Reactors”...
4

A double strand DNA break model of photon and electron relative biological effectiveness

Bellamy, Michael Bruce 03 April 2013 (has links)
The ICRP recommends a radiation weighting factor of one for all low-LET radiation. However, many experimental studies find inconsistencies between low-LET RBE and the ICRP's current radiation weighting factor. Generally, there is evidence that dependence exists between radiation energy and radiation RBE where lower energy radiations tend to have a greater biological effect than higher energy radiation. Specifically, the radiations of tritium and carbon K-shell x-rays have been studied in numerous experiments and the biological effects of both of these radiations are consistently greater than that of Co-60. In this work, the relationship between radiation energy and radiation effect has been investigated with the use of a newly developed double strand break (DSB) yield estimation algorithm. This algorithm makes use of a detailed solenoidal 30 nm DNA chromatin model to describe the radiation-sensitive biological target. In addition to the DNA model, NOREC, an event by event Monte Carlo code, was used in this algorithm to characterize the electron track. As an alternative to the conventional approach of computationally simulating DNA damage by spatial overlay of an electron track on DNA, this algorithm instead focuses on quantifying the distance between ionizations in an electron track and next determining the likelihood that any given ionization pair forms a DSB. The first step of the algorithm involves electron characterization while the second step relies on DNA molecule characterization. By assuming a DSB biological endpoint and determining the DSB yield as a function of electron energy, energy dependent RBE values were estimated for monoenergetic electrons from 10 eV to 1 MeV. Photon RBE values, x-ray RBE values and radionuclide RBE values were also calculated and reported in this work in addition to electron RBE values. Photon RBE values were estimated based upon the electron RBE calculation. Photon RBE values were reported from 1 eV to 10 MeV. In turn, x-ray RBE values were calculated based upon photon values for several tube voltage and filter combinations. Finally, RBE values for over 1000 radionuclides were estimated and reported.
5

Annual Report 2014 - Institute of Resource Ecology

Stumpf, Thorsten, Foerstendorf, Harald, Bok, Frank, Richter, Anke January 2015 (has links)
The Institute of Resource Ecology (IRE) is one of the eight institutes of the Helmholtz-Zentrum Dresden – Rossendorf (HZDR). The research activities are mainly integrated into the program “Nuclear Waste Management, Safety and Radiation Research (NUSAFE)” of the Helmholtz Association (HGF) and focused on the topics “Safety of Nuclear Waste Disposal” and “Safety Research for Nuclear Reactors”. Additionally, various activities have been started investigating chemical and environmental aspects of processing and recycling of strategic metals, namely rare earth elements. These activities are located in the HGF program “Energy Efficiency, Materials and Resources (EMR)”. Both programs, and therefore all work which is done at IRE, belong to the research sector “Energy” of the HGF. The research objectives are the protection of humans and the environment from hazards caused by pollutants resulting from technical processes that produce energy and raw materials. Treating technology and ecology as a unity is the major scientific challenge in assuring the safety of technical processes and gaining their public acceptance. We investigate the ecological risks exerted by radioactive and nonradioactive metals in the context of nuclear waste disposal, the production of energy in nuclear power plants, and in processes along the value chain of metalliferous raw materials. A common goal is to generate better understanding about the dominating processes essential for metal mobilization and immobilization on the molecular level by using advanced spectroscopic methods. This in turn enables us to assess the macroscopic phenomena, including models, codes, and data for predictive calculations, which determine the transport and distribution of contaminants in the environment.
6

Annual Report 2016 Institute of Resource Ecology

Stumpf, Thorsten, Foerstendorf, Harald, Bok, Frank, Richter, Anke 21 March 2017 (has links)
The Institute of Resource Ecology (IRE) is one of the eight institutes of the Helmholtz-Zentrum Dresden – Rossendorf (HZDR). The research activities are mainly integrated into the program “Nuclear Waste Management, Safety and Radiation Research (NUSAFE)” of the Helmholtz Association (HGF) and focused on the topics “Safety of Nuclear Waste Disposal” and “Safety Research for Nuclear Reactors”...
7

Radiation-induced deregulation of PiRNA pathway proteins : a possible molecular mechanism underlying transgenerational epigenomic instability

Merrifield, Matthew, University of Lethbridge. Faculty of Arts and Science January 2011 (has links)
PiRNAs and their Piwi family protein partners are part of a germline specific epigenetic regulatory mechanism essential for proper spermatogenesis, silencing of transposable elements, and maintaining germline genome integrity, yet their role in the response of the male germline to genotoxic stress is unknown. Ionizing radiation (IR) is known to cause transgenerational genome instability that is linked to carcinogenesis. Although the molecular etiology of IR-induced transgenerational genomic instability is not fully understood, it is believed to be an epigenetically mediated phenomenon. IR-induced alterations in the expression pattern of key regulatory proteins involved in the piRNA pathway essential for paternal germline genome stability may be directly involved in producing epigenetic alterations that can impact future generations. Here we show whole body and localized X-irradiation leads to significant altered expression of proteins that are necessary for, and intimately involved in, the proper functioning of the germline specific piRNA pathway in mice and rats. In addition we found that IR-induced alterations to piRNA pathway protein levels were time and dose dependent. / ix, 123 leaves : ill. (some col.) ; 29 cm
8

Role of eIF3a expression in cellular sensitivity to ionizing radiation treatments by regulating synthesis of NHEJ repair proteins

Tumia, Rima Ahmed .N. Hashm 11 November 2015 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Translation Initiation in protein synthesis is a crucial step controlling gene expression that enhanced by eukaryotic translation initiation factors (eIFs). eIF3a, the largest subunit of eIF3 complexes, has been shown to regulate protein synthesis and cellular response to cisplatin treatment. Its expression has also been shown to negatively associate with prognosis. In this study, we tested a hypothesis that eIF3a regulates synthesis of proteins important for repair of double strand DNA breaks induced by ionizing radiation (IR). We found that eIF3a up-regulation sensitizes cellular response to IR while its knockdown causes resistance to IR. We also found that eIF3a over-expression increases IR-induced DNA damage and decreases Non-Homologous End Joining (NHEJ) activity by suppressing expression level of NHEJ repair proteins such as DNA-PKcs and vice versa. Together, we conclude that eIF3a plays an important role in cellular response to DNA-damaging treatments by regulating synthesis of DNA repair proteins and, thus, eIIF3a likely plays an important role in the outcome of cancer patients treated with DNA-damaging strategies including ionizing radiation.

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