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TL;DR: In this paper, the authors used quasi-elastic neutron scattering to examine the diffusion process of lipid molecules in fluid DMPC membranes, and found that the motion over length scales greater than the lipid diameter could be characterized as a continuous diffusion process, with a diffusion coefficient of D = 64 × 10−12 m2/s.
Abstract: Diffusion is the primary mechanism for movement of lipids and proteins in the lateral direction of a biological membrane. In this paper we have used quasi-elastic neutron scattering to examine the diffusion process of lipid molecules in fluid DMPC membranes. We found that the motion over length scales greater than the lipid diameter could be characterized as a continuous diffusion process, with a diffusion coefficient of D = 64 × 10−12 m2/s. The continuous diffusion model has been successfully used in the past to describe the motion of lipid over long length scales. However, the focus of this measurement was to determine how the character of the molecular motion changes on length scales shorter than the nearest neighbour distance. At very short length scales (<2.37 A), we see first experimental evidence for a short-range flow-like ballistic motion.
58 citations
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TL;DR: In this paper, the defect structure of B2-type Fe1 − cAlc alloys (0.44 < c ≤ 0.51) was investigated by in-situ neutron diffraction measurements in the temperature range from room temperature to 1260-1300 K.
58 citations
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TL;DR: In oxygenated tumor and normal cells, mitochondria, rather than the nucleus, are the primary loci of radiotherapy effects, especially for low linear energy transfer radiation, which can be explained by radiation-induced effects in mitochondria that generate reactive oxygen species, which in turn indirectly target nuclear DNA.
Abstract: // Richard B. Richardson 1,2 and Mary-Ellen Harper 3 1 Canadian Nuclear Laboratories (CNL), Radiobiology and Health, Chalk River Laboratories, Chalk River, ON, Canada 2 McGill Medical Physics Unit, Cedars Cancer Center-Glen Site, Montreal, QC, Canada 3 Department of Biochemistry Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada Correspondence to: Richard B. Richardson, email: // Keywords : mitochondria, oxidative stress, oxygen effect, radiation therapy, therapy resistance Received : November 04, 2015 Accepted : January 29, 2016 Published : February 15, 2016 Abstract It has been more than 60 years since the discovery of the oxygen effect that empirically demonstrates the direct association between cell radiosensitivity and oxygen tension, important parameters in radiotherapy. Yet the mechanisms underlying this principal tenet of radiobiology are poorly understood. Better understanding of the oxygen effect may explain difficulty in eliminating hypoxic tumor cells, a major cause of regrowth after therapy. Our analysis utilizes the Howard-Flanders and Alper formula, which describes the relationship of radiosensitivity with oxygen tension. Here, we assign and qualitatively assess the relative contributions of two important mechanisms. The first mechanism involves the emission of reactive oxygen species from the mitochondrial electron transport chain, which increases with oxygen tension. The second mechanism is related to an energy and repair deficit, which increases with hypoxia. Following a radiation exposure, the uncoupling of the oxidative phosphorylation system (proton leak) in mitochondria lowers the emission of reactive oxygen species which has implications for fractionated radiotherapy, particularly of hypoxic tumors. Our analysis shows that, in oxygenated tumor and normal cells, mitochondria, rather than the nucleus, are the primary loci of radiotherapy effects, especially for low linear energy transfer radiation. Therefore, the oxygen effect can be explained by radiation-induced effects in mitochondria that generate reactive oxygen species, which in turn indirectly target nuclear DNA.
57 citations
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TL;DR: In this article, the authors measured the temperature dependence of the cell parameter of cubic β-cristobalite up to 1300°C by high-precision X-ray powder diffraction.
Abstract: We have measured the temperature dependence of the cell parameter of cubic β-cristobalite up to 1300° C by high-precision X-ray powder diffraction. The thermal expansion coefficient decreases on heating, until above 1000° C the cell parameter is virtually constant in value. We discuss this change in the thermal expansion with reference to the behaviour of low-frequency rigid unit modes and fluctuations associated with the α-β phase transition.
57 citations
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TL;DR: In this article, experimental data on Q -values, β end-point energies, half-lives, and branching ratios pertaining to superallowed J π → Jπ� (J ≠ 0) β-transitions are compiled and evaluated.
57 citations
Authors
Showing all 2298 results
Name | H-index | Papers | Citations |
---|---|---|---|
Michael D. Guiver | 78 | 288 | 20540 |
Robert J. Birgeneau | 78 | 587 | 22686 |
Mike D. Flannigan | 71 | 211 | 21327 |
Martin T. Dove | 61 | 396 | 14767 |
Luis Rodrigo | 58 | 341 | 12963 |
André Longtin | 56 | 260 | 16372 |
David Mitlin | 56 | 196 | 15479 |
John Katsaras | 55 | 220 | 9263 |
John E. Greedan | 55 | 391 | 12171 |
Gang Li | 48 | 406 | 7713 |
Matthew G. Tucker | 45 | 224 | 7288 |
Bruce D. Gaulin | 45 | 284 | 6698 |
Erick J. Dufourc | 43 | 144 | 5882 |
Norbert Kučerka | 43 | 119 | 7319 |
Stephen J. Skinner | 42 | 194 | 8522 |