Theoretical studies of physical and chemical aspects of primary processes in fundamental radiobiology

基础放射生物学初级过程的物理和化学方面的理论研究

• 批准号: 9020-2010
• 负责人: JayGerin, JeanPaul
• 金额: $ 1.97万
• 依托单位: Université de Sherbrooke
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=544584
• 关键词: Theoretical; studies; physical; chemical; aspects

If, nowadays, a panorama of the phenomena that underly the radiation chemistry of aqueous systems has reasonably been obtained in a number of cases, it appears that certain key aspects of this radiolysis are not yet fully resolved. This is especially true for the fundamental processes that link chemistry with the early physical interactions initiated by radiation. For example, recent fascinating observations have suggested the existence of new mechanisms in liquid-water radiolysis at very short times that now have to be identified and quantified. Bridging the gap in our understanding of this physicochemical interface is of obvious relevance to radiobiology and related science (e.g., free-radical biology) as liquid water is by far the most abundant constituent of biological cells. Knowledge of this "physicochemical" stage of radiolysis is central to a reliable description of the chemical nature and spatial distribution of the reactive species produced initially and precursors of radiobiological damage. This is also true for the radiolysis due to high linear energy transfer (LET) radiations, where it is critical to understand the complex nature of heavy-ion tracks (i.e., the "track structure") and their chemical effects (such as multiple ionization, Coulomb explosion, and thermal spike) for a number of practical reasons (e.g., hadrontherapy, space radiation effects). This is true as well when we want to account for the pivotal role played in the early stages of radiation chemistry by the numerous low-energy secondary electrons generated in the slowing of primary ionizing radiations, or for the fact that the aqueous medium itself is not continuous on a molecular scale. Using state-of-the-art stochastic Monte-Carlo methods and molecular dynamics calculations in combination with the knowledge gained from current experimental efforts, the proposed research program is aimed at designing experiment-and-theory based models to help advance our understanding of those challenging areas of the radiolysis of aqueous systems for which, we feel, a molecular-level characterization of the underlying chemistry is essential to produce a complete, accurate picture of this radiolysis. It is, without doubt, part of a major challenge in fundamental radiobiology.

现在，如果在许多情况下，已经合理地获得了水体系辐射化学背后现象的全貌，那么似乎这种辐射分解的某些关键方面还没有完全解决。对于将化学与辐射引发的早期物理相互作用联系起来的基本过程尤其如此。例如，最近令人着迷的观察表明，在很短的时间内存在液态水辐射分解的新机制，现在必须加以识别和量化。弥合我们对这种物理化学界面的理解的差距与放射生物学和相关科学（例如自由基生物学）明显相关，因为液态水是迄今为止生物细胞中最丰富的成分。了解辐射分解的这一“物理化学”阶段，对于可靠地描述最初产生的反应物质的化学性质和空间分布以及辐射生物损伤的前体至关重要。对于高线性能量传递（LET）辐射引起的辐射分解也是如此，其中理解重离子轨道（即“轨道结构”）的复杂性质及其化学效应（如多重电离，库仑爆炸和热峰值）至关重要，因为许多实际原因（例如强子疗法，空间辐射效应）。当我们想要解释在辐射化学的早期阶段，在减慢初级电离辐射过程中产生的大量低能次级电子所起的关键作用时，或者当我们想要解释水介质本身在分子尺度上不是连续的这一事实时，这也是正确的。利用最先进的随机蒙特卡罗方法和分子动力学计算，结合从目前的实验努力中获得的知识，提出的研究计划旨在设计基于实验和理论的模型，以帮助我们更好地理解水系统辐射分解的那些具有挑战性的领域，我们认为，潜在化学的分子水平表征对于产生一个完整的，放射溶解的准确图片。毫无疑问，这是基础放射生物学重大挑战的一部分。