微分吸收法测量二极管电压

给出了微分吸收法测量二极管电压的基本原理和实验结果。利用MCNP程序对轫致辐射-衰减-探测器系统建模,模拟得到了输出剂量与二极管工作电压关系拟合曲线。建立了微分吸收法测量二极管电压测量系统,通过在探测器前端放置不同厚度的吸收片,得到了衰减程度不同的波形。结合理论计算的拟合曲线和实验波形,利用迭代法计算得到了晨光号加速器二极管电压,电压峰值为0.58 MV。和传统方法所测得二极管工作电压进行了比较,结果较为一致。     

Toward two-dimensional nanometer resolution hard X-ray differential-interference-contrast imaging using modified photon sieves

In this Letter, we report a significant step forward in the design of single-optical-element optics for two-dimensional (2D) hard X-ray differential-interference-contrast (DIC) imaging based on modified photon sieves (MPSs). MPSs were obtained by a modified optic, i.e., combining two overlaid binary gratings and a photon sieve through two logical XOR operations. The superior performance of MPSs was demonstrated. Compared to Fresnel zone plates-based DIC diffractive optical elements (DOEs), which help to improve contrast only in one direction, MPSs can provide better resolution and 2D DIC imaging. Compared to normal photon sieves, MPSs are capable of imaging at a significantly higher image contrast. We anticipate that MPSs can provide a complementary and versatile high-resolution nondestructive imaging tool for ultra-large-scale integrated circuits at 45 nm node and below.     

Fault-tolerant panconnectivity of augmented cubes

The augmented cube AQ _n is a variation of the hypercube Q _n . This paper considers the panconnectivity of AQ _n (n ⩾ 3) with at most 2n−5 faulty vertices and/or edges and shows that, for any two fault-free vertices u and v with distance d in AQ _n , there exist fault-free uv-paths of every length from d + 2 to 2 ⁿ − f − 1, where f is the number of faulty vertices in AQ _n . The proof is based on an inductive construction.     

Quantum Euler-Poisson System: Local Existence of Solutions

The one-dimensional transient quantum Euler-Poisson system for semiconductors is studied in a bounded interval. The quantum correction can be interpreted as a dispersive regularization of the classical hydrodynamic equations and mechanical effects. The existence and uniqueness of local-in-time solutions are proved with lower regularity and without the restriction on the smallness of velocity, where the pressure-density is general (can be non-convex or non-monotone).     

Nonlinear Stability of Shock Profiles for Non-convex Model Equations with Degenerate Shock

This paper is concerned with the stability of shock profiles for one-dimensional non-convex equations of viscous materials. The main purpose is to show that the shock profile solution is stable in an appropriate weighted norm space for the case of the degenerate shock, provided that the shock is weak and the initial disturbance is small and of integral zero. The proof is given by means of an elementary but technical weighted energy method to the integrated system of the original one. Moreover, the stability result can be applied to the equation of van der Waals fluid and viscoelascity.     

一台14.5GHz新型高磁场高电荷态ECR离子源

自行研制成功一台14.5GHz新型高磁场高电荷态电子回旋共振(ECR)离子源.描述了该离子源结构特点、参数优化及其磁场分布,并给出了调试测量结果.该离子源轴向磁镜场在轴线上的最高磁场可达1.5T,六极永磁体在弧腔内表面磁场可达1.0T.经初步调试,可得到0⁷+140eμA,Ar¹¹+185eμA,Xe²⁶⁺50eμA.所得结果与1998年国际上最好的ECR离子源进行了比较.     

前舱物对低速大质量平头弹侵彻金属薄板的影响

为了研究前舱物对低速大质量平头弹侵彻金属薄靶的影响,根据前舱物的力学特性,将前舱物等效为轻质泡沫铝材料,建立了含前舱物的平头弹结构有限元分析模型,开展了不同工况下带前舱物平头弹侵彻金属薄板的数值模拟计算,分析了带前舱物平头弹侵彻金属薄板的过程,对比了带前舱物平头弹和不计前舱物平头弹在不同工况下剩余速度的差异。数值计算结果表明:带前舱物平头弹与不计前舱物平头弹的侵彻过程存在明显差异,但靶板破坏模式相同;前舱物等效材料的屈服强度对平头弹侵彻性能的影响很小,可以忽略不计;前舱物有助于提高平头弹侵彻金属薄板的能力,但提升幅度有限。在实际工程应用中,可以忽略前舱物对平头弹侵彻金属薄板的影响。     

Coupling molecular rigidity and flexibility on fused backbones for NIR-II photothermal conversion

Great attention is being increasingly paid to photothermal conversion in the near-infrared (NIR)-II window (1000–1350 nm), where deeper tissue penetration is favored. To date, only a limited number of organic photothermal polymers and relevant theory have been exploited to direct the molecular design of polymers with highly efficient photothermal conversion, specifically in the NIR-II window. This work proposes a fused backbone structure locked via an intramolecular hydrogen bonding interaction and double bond, which favors molecular planarity and rigidity in the ground state and molecular flexibility in the excited state. Following this proposal, a particular class of NIR-II photothermal polymers are prepared. Their remarkable photothermal conversion efficiency is in good agreement with our strategy of coupling polymeric rigidity and flexibility, which accounts for the improved light absorption on going from the ground state to the excited state and nonradiative emission on going from the excited state to the ground state. It is envisioned that such a concept of coupling polymeric rigidity and flexibility will offer great inspiration for developing NIR-II photothermal polymers with the use of other chromophores.

Low bandgap and large deformation generally conflict each other. This work couples molecular rigidity and flexibility by intramolecular hydrogen bonds and double bonds to achieve NIR-II light absorption and reinforced internal conversion at the same time.     

室温离子液体作溶剂顶空气-质联用测定药物中溶剂残留

基于室温离子液体无蒸汽压、良好溶解性和分散性的特点,用室温离子液体[bm im][PF6]作溶剂顶空气-质联用测定非那雄胺中二氯甲烷、三氯甲烷及二氧六环的残留量,优化了顶空气-质联用分析条件。二氯甲烷、三氯甲烷及二氧六环的检出限分别为0.2、0.02和0.50 ng,线性相关系数大于0.99;相对标准偏差(RSD)0.39%~4.60%;回收率为90.5%~111.9%。室温离子液体作为顶空溶剂的灵敏度有所提高。