Research On Saddle-like Radiation Dose-response Curve And Sputtering Effect Of Low Energy Ion

This work comprises two research topics: 1. simulation of the dose-response curve of plant irradiated by low energy ion beam and study on the mechanism for the froming of saddle-like dose-response, 2. sputtering effect and its emulation of low energy ion implantation into biological targets.Linear-Quadric model, a negative exponential function deduced from Target Theory, is the classic equation in delineating radiation dose-response curve that manifests a continous downward bending shape as dose increasing. However, recent findings of dose-response curve in low dose zone prove disobidient of L-Q model , which shows the complication of low dose radiation bioeffect. Saddle-like dose-response curve, together with adaptive and hormeotic effect prompt new prolbems in the interaction of radiation and organism, and promote the application and development of radiation in breeding, medical and other field.In the first part of this research, the convergency and initial solution dependence of saddle-like dose-response curve simulation are discussed based on published data. Rice seeds were irradiated byγray at different dose, and the effect of NaCl stress, on behalf of adverse enviromental factors, on the shape of radiation dose-response curve was investigated. Radiation dose-seedling height curve gradually changed from L-Q model to saddle-like shape when stressed with 0.02 to 0.1M NaCl during germination. Low dose radiation induced antagnism to stress is an important causation to saddle-like dose-response curve.Low energy heavy ion, belonging to high linear energy trasmit radiation, is intensivly used in crop breeding and microbial traits improvement. Morever, sputtering effect generated by low energy heavy ion bombardment onto biomaterials could form itching and crater on cell surface, which may facilliate plant cell absorbbing exogenous DNA bypass thick cell wall.In the second part of this work, the effects of atom number, energy and incidence angle of implatated ion into on ion range and sputtering rate were simulated ion implatation into ideal biomaterial with TRIM programme.