中国科学院近代物理研究所重离子束治癌进展

介绍了中国科学院近代物理研究所在重离子束治癌研究和治疗装置研制方面的最新进展, 以及中国科学院近代物理研究所重离子束治癌的发展规划。     

低剂量辐射超敏感性研究进展

细胞低剂量辐射反应是目前国际上研究的热点。 介绍了哺乳动物细胞的低剂量反应——辐射超敏感性(HRS)和增强的辐射抗性(IRR), 即细胞在大约0.1 Gy时会出现单位剂量细胞杀伤增强现象, 随着剂量的升高, 细胞的IRR增强, 到1 Gy以上细胞存活符合线性平方模型。 评述了近年来国际上低剂量HRS领域的研究进展, 着重讨论了HRS/IRR可能的分子机理及辐射传能线密度与HRS/IRR的关系, 并对HRS/IRR在肿瘤临床放射治疗中的应用做了初步的探讨, 最后提出了该领域进一步研究的一些问题。At present, cell response to low dose radiation is attracting growing interests all over the world. Hyper radiosensitivity (HRS) and increased radioresistance (IRR) were introduced in this paper. This phenomenon means that an excess cell killing per unit dose appears at about 0.1 Gy (HRS) and then the cell radiation sensitivity increases with increasing dose (IRR). When the dose outstrips 1 Gy, the cell surviving fraction coincides with the value predicted by the commonly accepted linear quadratic (LQ) model. We further reviewed the progress to date in the study of low dose HRS, especially the possible molecular mechanisms underlying HRS/IRR and the relationship between HRS/IRR and linear energy transfer (LET). An initial insight into the clinical application of HRS/IRR in tumor radiotherapy was presented as well.Moreover, several topics concerning the HRS/IRR investigation, which deserved to be reinforced, were put forward.     

A method to measure the Brillouin frequency shift of the medium through Brillouin amplification ratio

In order to measure the Brillouin frequency shift (BFS) of the medium, this paper proposes a method using mixtures in a two-cell stimulated Brillouin scattering system, which uses a medium to be measured as amplifier medium and a mixture medium as generator medium. The seed light from the generator gains effective amplification in the amplifier and the amplification ratio changes with the mixing fraction. Only when the BFS of the mixture medium is equal to that of the medium in the amplifier does the seed light obtain the maximum amplification ratio. The method has the advantage of independence of the wavelength of the incident light.     

莫来石的低温合成与结构研究

通过在高岭土中引入质量分数为1%～5%的钒以后,在700℃左右的较低温度下观察到莫来石相的生成,并结合酸、碱抽提反应过程制得较纯的莫来石.进一步研究了低温莫来石点阵参数的测定方法,发现低温钒-莫来石的晶胞体积比常规的高温莫来石大,表明钒进入了莫来石的骨架结构.另外,低温莫来石的形成动力学可表述为钒-高岭石低温共熔体迁移过程.     

中能重离子束深度剂量分布计算

提出了称之为复合歧离算法的中能重离子束深度剂量分布计算方法,并计算了中能C,O离子束的Bragg相对剂量分布曲线,同实验测量结果进行了比较,计算与实验测量符合得很好.证实了复合歧离算法的合理性及由它计算Bragg曲线的可靠性.补充和完善了离子束的深度剂量分布计算原理与方法.     

活性炭负载镍催化二苯并呋喃加氢的研究

以活性炭负载镍为催化剂,对二苯并呋喃催化加氢工艺进行了研究,通过GC/MS分析加氢产品的组成,对加氢组份含量变化趋势进行分析,并提出了加氢反应路线。同时对二苯并呋喃加氢制备2-环己基环己醇的反应进行了研究,考察反应温度、反应压力和反应时间对产品收率的影响。实验结果表明:在甲苯溶剂中,反应温度150℃,反应压力0.5 MPa,反应时间为12 h,产品收率为63.3%,纯度98%(GC)。产品结构经IR和~1H-NMR表征     

Pd(100)表面Ag原子对CCH_3吸附影响的理论研究

采用密度泛函理论方法,运用周期性表面模型对CCH_3在PdAg_x/Pd(100)表面的垂直吸附进行了结构优化和能量计算.结果表明:在金属Pd中掺杂Ag可以有效地降低金属表面对CCH_3的吸附效果,由于Ag的金属性较Pd强,Ag的加入改变了其金属表面的电子排布.当CCH_3吸附在PdAg_x/Pd(100)表面时,随着Ag含量的增加,表面对CCH_3的电子供给慢慢由Pd原子提供大量电子转向为Ag原子提供大量电子,而C—Ag键强度较弱,从而进一步降低了CCH_3与金属表面的吸附效果.     

非铁电压电复合陶瓷SrTiO3-Bi12TiO20（ST-BT）的正电子湮没谱学研究

采用传统陶瓷烧结工艺成功制备出新型非铁电压电复合陶瓷SrTiO₃-Bi₁₂TiO₂₀（ST-BT）,利用正电子湮没技术,对ST-BT复合陶瓷烧结过程进行了研究,讨论了烧结过程中材料内部的缺陷变化特征,给出了烧结温度对该复合陶瓷结晶度和缺陷结构的影响.发现烧结温度在860—940℃,烧结时间为3 h的实验条件下,ST-BT复合陶瓷已趋于稳定,出现了大量的单空位型缺陷.烧结温度超过980℃将引起Bi₁₂TiO₂₀相的大量分解,杂相的出现造成缺陷的聚集,形成大尺度的微空洞.实验结果表明,烧结温度在920—940℃的烧结条件下,ST-BT复合陶瓷的结构特性及压电性能均表现出较好的稳定性.     

DROPLET COLLISION AND COALESCENCE MODEL

A new droplet collision and coalescence model was presented,a quick-sort method for locating collision partners was also devised and based on theoretical and experimental results,further advancement was made to the droplet collision outcome. The advantages of the two implementations of smoothed particle hydrodynamics (SPH) method were used to limit the collision of droplets to a given number of nearest droplets and define the probability of coalescence,numerical simulations were carried out for model validation.Results show that the model presented is mesh-independent and less time consuming,it can not only maintains the system momentum conservation perfectly,but not susceptible to initial droplet size distribution as well.