SPRR-300研究堆随堆辐照石墨的中子辐照效应北大核心CSCD

随SPRR-300研究堆约30 a的长时间运行,位于活性区附近的石墨箱体经历了长期的中子辐照。在长期服役的石墨箱体上取样,研究了其热学、力学以及微观结构变化,并与商用IG110,NG-CT-10石墨进行了对比。研究结果表明,经长时间低剂量率的中子辐照后,SPRR-300堆内随堆辐照石墨的晶格中出现了明显的辐照损伤缺陷,这些缺陷主要为位错环、层错、孔洞和微裂纹等,并出现了一定程度的非晶化。这些辐照损伤缺陷直接或间接地引起了石墨热学、力学性能的变化,主要表现为热膨胀系数、热扩散系数、抗压强度和抗弯强度的下降以及弯曲弹性模量的上升。     

Development of an electronic stopping power model based on deep learning and its application in ion range prediction

Deep learning algorithm emerges as a new method to take the raw features from large dataset and mine their deep implicit relations, which is promising for solving traditional physical challenges. A particularly intricate and difficult challenge is the energy loss mechanism of energetic ions in solid, where accurate prediction of stopping power is a long-time problem. In this work, we develop a deep-learning-based stopping power model with high overall accuracy, and overcome the long-standing deficiency of the existing classical models by improving the predictive accuracy of stopping power for ultra-heavy ion with low energy, and the corresponding projected range. This electronic stopping power model, based on deep learning algorithm, could be hopefully applied for the study of ion-solid interaction mechanism and enormous relevant applications.     

Microwave absorption properties regulation and bandwidth formula of oriented Y2Fe17N3-δ@SiO2/PU composite synthesized by reduction-diffusion method

As concepts closely related to microwave absorption properties, impedance matching and phase matching were rarely combined with material parameters to regulate properties and explore related mechanisms. In this work, reduction-diffusion method was innovatively applied to synthesize rare earth alloy Y$_{2}$Fe$_{17}$. In order to regulate the electromagnetic parameters of absorbers, the Y$_{2}$Fe$_{17}$N$_{3-\delta }$ particles were coated with silica (Y$_{2}$Fe$_{17}$N$_{3-\delta }$@SiO$_{2}$) and absorbers with different volume fractions were prepared. The relationship between impedance matching, matching thickness, and the strongest reflection loss peak (${\rm RL}_{\rm min}$) was presented obviously. Compared to the microwave absorption properties of Y$_{2}$Fe$_{17}$N$_{3-\delta }$/PU absorber, Y$_{2}$Fe$_{17}$N$_{3-\delta }$@SiO$_{2}$/PU absorbers are more conducive to the realization of microwave absorption material standards which are thin thickness, light weight, strong absorbing intensity, and broad bandwidth. Based on microwave frequency bands, the microwave absorption properties of the absorbers were analyzed and the related parameters were listed. As an important parameter related to perfect matching, reflection factor ($\sqrt {ărepsilon_{\rm r}/\mu_{\rm r}}$) was discussed combined with microwave amplitude attenuation. According to the origin and mathematical model of bandwidth, the formula of EAB (${\rm RL}<-10$ dB) was derived and simplified. The calculated bandwidths agreed well with experimental results.     

固相萃取-液相色谱-串联质谱法检测化妆品中的双酚A残留

建立了化妆品中双酚A残留的高效液相色谱-串联四极杆质谱联用测定方法.样品经碱性乙腈提取,氨基固相小柱净化而后测定.方法在2.0～ 100.0μg/L范围内呈良好线性,相关系数为0.99998,方法的检出限为0.02 mg/kg.在0.10,1.0,10.0 mg/kg 3个加标水平下,加标回收率为92.4％ ～98.8％,相对标准偏差为6.0％～9.4％.     

ADSORPTION BEHAVIOR OF AMINO ACIDS ON COPPER SURFACES

The major results of a series of our recent investigations on the adsorption of eight amino acids on Cu(001) and (111) surfaces are reviewed in the present paper. In all studied cases the molecules adsorb onto the surface in their anionic form. With the increase of the coverage three different 2D phases of the adsorbates, that is, the 2D lattice gas, intermediate, and solid phases, appear sequentially, although for few systems one or two of them do not appear. In both the 2D lattice gas and intermediate phases the molecules "stand" with their two oxygen "feet" on the surface and the intermolecular interactions are repulsive, although in the former they can diffuse frequently whereas in the latter they are discommensurate in one direction with the substrate. In the solid phase the molecules "lie" down on the surface to form commensurate superstructures. Adsorption of amino acids may often induce step faceting as well as bunching to form facets. Adsorption of L-lysine on Cu(001) may cause steps bunching to form facets with all the same chirality. Our preliminary results show that it is possible to manipulate individual molecules with the STM tip even at room temperature. These results may have applications in nano-materials, nano-technology, and very likely also in chiral separations or enantioselective heterogeneous catalysis.     

X射线双晶衍射技术的发展及应用

简要介绍了X射线双晶衍射技术的原理;描述了双晶衍射技术的发展与演化,中简要讲述了多晶衍射技术的应用范围及应用鑫晶衍射仪所能做的工作。     

新型含酯基的可生物降解聚碳酸酯的合成

通过2，2-二羟甲基-丙二酸二甲酯与氯甲酸乙酯的反应合成了环状碳酸酯单体5，5-二甲氧羰基-1，3-二氧六环-2-酮，再以异辛酸亚锡为催化剂，在不同温度下进行本体开环聚合，得到新型含酯基的聚碳酸酯．单体和聚合物结构经红外光谱(IR)、核磁共振氢谱(1^H NMR)及核磁共振碳谱(^12C NMR)表征．结果表明，开环聚合反应的产率和分子量随温度的升高而增加，但温度高于100℃时开环聚合会发生一定程度的脱羧反应，研究得出该聚合反应合适的反应条件为：反应温度90℃，反应时间12h，聚合过程中基本无脱羧反应发生。     

硼酸类化学传感器的研究进展

检测和识别体内某些物质,例如唾液酸化LewisA/X,能够为疾病的诊断、治疗、预后、分子示踪及深入研究相关疾病机理等方面提供重要参考.因此,开发高选择性、高灵敏度的化学传感器具有重要价值.苯基硼酸化合物由于其特殊结构,能够与糖、儿茶酚胺以及氟化物、氰化物等路易斯碱相互作用,使得其能够作为传感器用于相关物质的荧光识别和检测;且此类化合物具有高选择性、高效能、分析速度快等优点.近几年,将硼酸与纳米粒子、量子点等新材料相结合,设计出性能更加优越的硼酸传感器.综述了硼酸类化合物在传感器方面的研究进展.     

基于自组装的纳米材料双芘的原位构筑、转化和生物效应研究

由于预自组装纳米材料的超结构和性能在复杂的生理状态下会发生变化,我们提出了一种新的"体内自组装"策略,即在体内原位构筑自组装纳米材料来代替预组装纳米材料.为了实现和研究体内自组装,开发了双芘建筑模块,该建筑模块组装成纳米材料时伴随着荧光的增强,可用于"观察"自组装过程及最终的自组装纳米材料.本文总结了双芘建筑模块用于体内自组装的优势,系统地介绍了体内自组装的策略.同时探讨了基于体内自组装和转化的双芘材料的生物效应和诊断治疗应用,并展望了双芘自组装纳米材料的未来发展前景.     

TBIR改性BIIR/NR共混物的结构与性能

研究了新型合成橡胶——高反式-1,4-丁二烯-异戊二烯共聚橡胶(TBIR)对全钢轮胎气密层并用橡胶——溴化丁基橡胶(BIIR)/天然橡胶(NR)(质量比70/30)的改性作用,探讨了BIIR/NR/TBIR共混物的交联密度、填料分散性及力学性能,特别是并用硫化胶的气密性及屈挠疲劳性能等.结果表明,与无定型的BIIR和NR相比,结晶性TBIR的引入提高了炭黑填充的BIIR/NR/TBIR混炼胶的强度和模量,且随着TBIR用量的增大,混炼胶中TBIR的结晶熔融峰更明显,混炼胶的强度与模量显著提高.硫化特性结果表明,随着TBIR用量的增大,BIIR/NR/TBIR共混物的硫化速率略有提高,交联密度略有降低;TBIR用量为10~30份(生胶总质量的10%~30%)时,BIIR/NR/TBIR硫化胶在机械性能基本保持不变的情况下,耐热氧老化性能提高10%以上,耐一级屈挠疲劳性能提升2~5倍,气密性提高17%.炭黑分散结果表明,经过动态疲劳实验BIIR/NR硫化胶中炭黑聚集体的平均粒径增大至11.5μm,明显大于BIIR/NR/TBIR硫化胶中炭黑聚集体的平均粒径.对含TBIR硫化胶在周期性应力应变过程中的结构演变及对耐疲劳裂纹引发性能的影响机制进行了探讨,结果表明,TBIR可改性BIIR或者BIIR/NR制备高抗裂口引发的全钢轮胎气密层材料.