Ionizing Radiation Effects on Interfaces in Carbon Nanotube-Polymer Composites

2001 ◽  
Vol 697 ◽  
Author(s):  
Julie P. Harmon ◽  
Patricia Anne O. Muisener ◽  
LaNetra Clayton ◽  
John D'Angelo ◽  
Arun K. Sikder ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Gamma Radiation ◽  
Total Dose ◽  
Dose Rate ◽  
Polymer Composites ◽  
Radiation Effects ◽  
Mechanical Analysis ◽  
Scanning Calorimetry ◽  
Radiation Induced ◽  
Radiation Induced Chemistry

AbstractThe purpose of this research was to probe nanotube-polymer composites for evidences of radiation induced chemistry at the interface of the host polymer and the nanotube structures. Single wall carbon nanotube (SWNT) / poly (methyl methacrylate) (PMMA) composites were fabricated and exposed to gamma radiation with a Co60 source at a dose rate of 1.28 X 106 rad/hour in an air environment for a total dose of 5.9 Mrads. Neat nanotube paper and neat PMMA were also exposed. Spun coat films of SWNT/PMMA were exposed to gamma radiation with a Ce157at a dose rate of 4.46 x 103 rad/hr for a total dose of 3.86 Mrads. Both irradiated and non-irradiated samples were compared. Glass transition temperatures were characterized by differential scanning calorimetry. Dynamic mechanical analysis and dielectric analysis evidenced changes in relaxations induced by irradiation. Irradiated composites exhibited radiation induced chemistry distinct from degradation effects noted in the pure polymer. Scanning electron microscopy provided images of the SWNTs and SWNT/PMMA interface before and after irradiation. This investigation imparts insight into the nature of radiation induced events in nanotubes and nanocomposites.

TOTAL DOSE EFFECTS IN LINEAR BIPOLAR INTEGRATED CIRCUITS

2004 ◽  
Vol 14 (02) ◽  
pp. 519-541 ◽  
Author(s):  
H. J. BARNABY
Keyword(s):  
Integrated Circuits ◽  
Total Dose ◽  
Radiation Effects ◽  
Rate Sensitivity ◽  
Circuit Parameter ◽  
Enhanced Sensitivity ◽  
Dose Effects ◽  
Radiation Induced ◽  
Total Dose Effects ◽  
Bipolar Circuit

Electronics systems that operate in space or strategic environments can be severely damaged by exposure to ionizing radiation. Space-based systems that utilize linear bipolar integrated circuits are particularly susceptible to radiation-induced damage because of the enhanced sensitivity of these circuits to the low rate of radiation exposure. The phenomenon of enhanced low-dose-rate sensitivity (ELDRS) demonstrates the need for a comprehensive understanding of the mechanisms of total dose effects in linear bipolar circuits. The majority of detailed bipolar total dose studies to date have focused on radiation effects mechanisms at either the process or transistor level. The goal of this text is to provide an overview of total dose mechanisms from the circuit perspective; in particular, the effects of transistor gain degradation on specific linear bipolar circuit parameters and the effects of circuit parameter degradation on select linear bipolar circuit applications.

scholarly journals Ubiquitination of p53 and p21 is differentially affected by ionizing and UV radiation.

1997 ◽  
Vol 17 (1) ◽  
pp. 355-363 ◽  
Author(s):  
C G Maki ◽  
P M Howley
Keyword(s):  
Gamma Radiation ◽  
Uv Radiation ◽  
Radiation Effects ◽  
P53 Protein ◽  
Proteolytic Pathway ◽  
Radiation Induced ◽  
The Stability ◽  
Gamma Irradiated ◽  
In Cells

Levels of the tumor suppressor protein p53 are normally quite low due in part to its short half-life. p53 levels increase in cells exposed to DNA-damaging agents, such as radiation, and this increase is thought to be responsible for the radiation-induced G1 cell cycle arrest or delay. The mechanisms by which radiation causes an increase in p53 are currently unknown. The purpose of this study was to compare the effects of gamma and UV radiation on the stability and ubiquitination of p53 in vivo. Ubiquitin-p53 conjugates could be detected in nonirradiated and gamma-irradiated cells but not in cells which were UV treated, despite the fact that both treatments resulted in the stabilization of the p53 protein. These results demonstrate that UV and gamma radiation have different effects on ubiquitinated p53 and suggest that the UV-induced stabilization of p53 results from a loss of p53 ubiquitination. Ubiquitinated forms of p21, an inhibitor of cyclin-dependent kinases, were detected in vivo, demonstrating that p21 is also a target for degradation by the ubiquitin-dependent proteolytic pathway. However, UV and gamma radiation had no effect on the stability or in vivo ubiquitination of p21, indicating that the radiation effects on p53 are specific.

Radiation Induced Dissolution of UO2

1990 ◽  
Vol 212 ◽  
Author(s):  
Hilbert Christensen
Keyword(s):  
Corrosion Rate ◽  
Gamma Radiation ◽  
Ambient Temperature ◽  
Dose Rate ◽  
Oxidation Mechanism ◽  
Sample Surface ◽  
Oh Radicals ◽  
Water Radiolysis ◽  
Radiation Induced ◽  
Polished Specimen

ABSTRACTIn order to be able to model the effect of water radiolysis on the dissolution of fuel in the disposal vault it is essential to study the oxidation mechanism. Radiolysis of water produces radicals and molecules, amongst them the oxidizing species H2O2 and OH radicals, and, in aerated solutions, O2- as well. These species are probably responsible for the oxidation and dissolution of UO2 observed in a number of experiments. In the present investigation the effect of the oxidizing species has been studied separately using suitable scavengers. A polished specimen of UO2 was immersed in water and irradiated at ambient temperature with Co-60 gamma radiation. After irradiation the amount of uranium which had dissolved, or deposited elsewhere than the sample surface, was measured, and the oxidation of the surface was determined, using ESCA and SIMS. In 50 mM H2O2 (without irradiation) the corrosion rate was 5±3 μg.cm−2d−1 after 6 d exposure at pH 8. Corresponding rates for oxidation by O2- and OH radicals were about 3 μg.cm−2d−1, (dose rate 600±90 Gy/h.)

scholarly journals Bio-Based Poly(butylene succinate)/Microcrystalline Cellulose/Nanofibrillated Cellulose-Based Sustainable Polymer Composites: Thermo-Mechanical and Biodegradation Studies

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1472 ◽  
Author(s):  
Oskars Platnieks ◽  
Sergejs Gaidukovs ◽  
Anda Barkane ◽  
Aleksandrs Sereda ◽  
Gerda Gaidukova ◽  
...  
Keyword(s):  
Polymer Composites ◽  
Microcrystalline Cellulose ◽  
Nanofibrillated Cellulose ◽  
Mechanical Analysis ◽  
Sem Analysis ◽  
Scanning Calorimetry ◽  
Butylene Succinate ◽  
Crystallinity Degree ◽  
Sustainable Housing ◽  
Degradation Temperature

Biodegradable polymer composites from renewable resources are the next-generation of wood-like materials and are crucial for the development of various industries to meet sustainability goals. Functional applications like packaging, medicine, automotive, construction and sustainable housing are just some that would greatly benefit. Some of the existing industries, like wood plastic composites, already encompass given examples but are dominated by fossil-based polymers that are unsustainable. Thus, there is a background to bring a new perspective approach for the combination of microcrystalline cellulose (MCC) and nanofibrillated cellulose (NFC) fillers in bio-based poly (butylene succinate) matrix (PBS). MCC, NFC and MCC/NFC filler total loading at 40 wt % was used to obtain more insights for wood-like composite applications. The ability to tailor the biodegradable characteristics and the mechanical properties of PBS composites is indispensable for extended applications. Five compositions have been prepared with MCC and NFC fillers using melt blending approach. Young’s modulus in tensile test mode and storage modulus at 20 °C in thermo-mechanical analysis have increased about two-fold. Thermal degradation temperature was increased by approximately 60 °C compared to MCC and NFC. Additionally, to estimate the compatibility of the components and morphology of the composite’s SEM analysis was performed for fractured surfaces. The contact angle measurements testified the developed matrix interphase. Differential scanning calorimetry evidenced the trans-crystallization of the polymer after filler incorporation; the crystallization temperature shifted to the higher temperature region. The MCC has a stronger effect on the crystallinity degree than NFC filler. PBS disintegrated under composting conditions in a period of 75 days. The NFC/MCC addition facilitated the specimens’ decomposition rate up to 60 days

Gamma radiation induced distribution of gold nanoparticles into carbon nanotube-polyaniline composite

2007 ◽  
Vol 67 (5) ◽  
pp. 811-816 ◽  
Author(s):  
Kwang-Pill Lee ◽  
Anantha Iyengar Gopalan ◽  
Padmanabhan Santhosh ◽  
Se Hee Lee ◽  
Young Chang Nho
Keyword(s):  
Gold Nanoparticles ◽  
Carbon Nanotube ◽  
Gamma Radiation ◽  
Radiation Induced

Total Dose Radiation Effects on COTS Array CCDs at Low Dose Rate

2014 ◽  
Author(s):  
Zujun Wang ◽  
Zhigang Xiao ◽  
Baoping He ◽  
Shaoyan Huang ◽  
Benqi Tang ◽  
...  
Keyword(s):  
Total Dose ◽  
Dose Rate ◽  
Radiation Effects ◽  
Low Dose ◽  
Low Dose Rate ◽  
Dose Radiation
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