CiADS束流负载效应前馈补偿的仿真评估

在高功率超导质子直线加速器中，束流负载效应是影响超导腔幅相稳定性的一个重要因素。本工作基于谐振腔建场模型，开发了超导腔系统束流负载效应的时域仿真程序，分析了束流负载效应对超导腔幅相稳定性的影响，并在C-ADS注入器II上通过相关实验测量对仿真结果进行了验证。利用该程序，评估了CiADS超导直线加速器脉冲束流的脉冲长度，以及前馈补偿的时序抖动和束流纹波等因素对腔中电磁场幅相稳定度的影响。仿真结果表明:在当前CiADS直线加速器设计参数下，为满足超导腔中电磁场0.1%与在高功率超导质子直线加速器中，束流负载效应是影响超导腔幅相稳定性的一个重要因素。本工作基于谐振腔建场模型，开发了超导腔系统束流负载效应的时域仿真程序，分析了束流负载效应对超导腔幅相稳定性的影响，并在C-ADS注入器II上通过相关实验测量对仿真结果进行了验证。利用该程序，评估了CiADS超导直线加速器脉冲束流的脉冲长度，以及前馈补偿的时序抖动和束流纹波等因素对腔中电磁场幅相稳定度的影响。仿真结果表明:在当前CiADS直线加速器设计参数下，为满足超导腔中电磁场0.1%与$0.1^{\circ}$的幅相稳定度指标，前馈时序抖动的偏差不能超过0.79 μs，束流流强的直流偏差不能超过0.9%，并且给出了束流纹波的最大抖动幅值与纹波频率之间的关系。这些结果将为CiADS超导直线加速器相关子系统技术指标的确定提供依据。     

氧化铟掺铪红外透明导电薄膜

采用射频磁控溅射与退火工艺相结合的方法,分别在石英和硒化锌(ZnSe)衬底上制备了掺铪氧化铟(IHfO)薄膜,掺杂比例In2O3∶HfO2为98wt.%∶2wt.%.测试了薄膜的组成结构和3～5μm红外波段的光电性质,分析了退火温度、薄膜厚度和氧气流速对薄膜性能的影响.X射线衍射、扫描电子显微镜和X射线能谱表明,制备的IHfO薄膜具有氧化铟的立方体结构,掺杂铪并没有影响氧化铟的生长方向,但是减小了晶格间距,铪与铟外层电子形成新的杂化轨道.傅里叶变换红外光谱表明,随着退火温度的增加,IHfO薄膜在3～5μm波段的透过率逐渐下降,沉积在ZnSe衬底上的薄膜具有更平稳的透过率,厚度为100nm薄膜在3～5μm波段平均透过率为68%.测试霍尔效应表明,随着氧气流速的增加,IHfO薄膜电阻率逐渐增加,载流子浓度减小,霍尔迁移率变化不明显.晶界散射是影响IHfO薄膜迁移率的主要因素,当氧气流速为0.3sccm时,薄膜最佳电阻率为3.3×10~(-2)Ω·cm.与透可见光波段的导电氧化铟锡(ITO)薄膜相比,制备的IHfO薄膜可以应用在3～5μm红外波段检测气体,红外制导等领域.     

电镀铜实验中镀层性质及其影响因素的探究*

电镀实验是电解原理应用的重要案例,通过实验不仅要获得定性的感性认知,还应该获得定量的理性数据。针对电镀铜实验,通过改变铜离子浓度、pH、电解时间、电解电压和电解温度等因素,探究其对镀层厚度、均匀性和致密性等性质的影响,在电解原理的基础上分析其形成机制,从而确定了电镀铜较适宜的操作条件,以此为学生开展电镀实验提供参考案例与研究思路。     

Palladium‐catalyzed decarboxylative coupling of α,β‐unsaturated carboxylic acids with aryl tosylates

We report a general method for selective cross‐coupling of α,β‐unsaturated carboxylic acids with aryl tosylates enabled by versatile Pd(II) complexes. This method features the general cross‐coupling of ubiquitous α,β‐unsaturated carboxylic acids by decarboxylation. The transformation is characterized by its operational simplicity, the use of inexpensive, air‐stable Pd(II) catalysts, scalability and wide substrate scope. The reaction proceeds with high trans selectivity to furnish valuable (E)‐1,2‐diarylethenes.     

Establishment and validation of an SIL-IS LC–MS/MS method for the determination of ibuprofen in human plasma and its pharmacokinetic study

In this work, we developed and validated a highly sensitive, rapid and stable LC–MS/MS method for the determination of ibuprofen in human plasma with ibuprofen-d3 as a stable isotopically labeled internal standard (SIL-IS). Human plasma samples were prepared by one-step protein precipitation. The chromatographic separation was achieved on a Poroshell 120 EC-C₁₈ (2.1 × 50 mm, 2.7 μm). Aqueous solution (containing 0.05% acetic acid and 5 mm NH₄Ac) and methanol were selected as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in negative ion mode. Multiple reaction monitoring mode was used for quantification using target fragment ions m/z 205.0 → 161.1 for ibuprofen and m/z 208.0 → 164.0 for SIL-IS, respectively. This method exhibited a linear range of 0.05–36 μg/ml for ibuprofen with correlation coefficient >0.99. Mean recoveries of ibuprofen in human plasma ranged from 78.4 to 80.9%. The RSD of intra- and inter-day precision were both < 5%. The accuracy was between 88.2 and 103.67%. The matrix effect was negligible in human plasma, including lipidemia and hemolytic plasma. A simple, efficient and accurate LC–MS/MS method was successfully established and applied to a pharmacokinetic study in healthy Chinese volunteers after a single oral administration of ibuprofen granules.     

Superconvergence of a two‐grid method for fourth‐order dispersive‐dissipative wave equations

In this paper, the superconvergence analysis of a two‐grid method (TGM) with low‐order finite elements is presented for the fourth‐order dispersive‐dissipative wave equations for a second order fully discrete scheme. The superclose estimates in the H¹‐norm on the two grids are obtained by the combination technique of the interpolation and Ritz projection. Then, with the help of the interpolated postprocessing technique, the global superconvergence properties are deduced. Finally, numerical results are provided to show the performance of the proposed TGM for conforming bilinear element and nonconforming element, respectively. It shows that the TGM is an effective method to the problem considered of our paper compared with the traditional Galerkin finite element method (FEM).     

A conjugated alkyne functional bicyclic polybenzoxazine with superior heat resistance

A difunctional benzoxazine (coPh‐apa) with a conjugated alkyne group is synthesized by the oxidative coupling reaction from a monocycle‐benzoxazine (Ph‐apa) containing an alkyne group. A model compound, 1,4‐diphenylbutadiyne (coPa), is used to study the curing reaction process of coPh‐apa by DSC, Fourier transform infrared spectroscopy, and ¹³C NMR, and the results suggest that the conjugated alkyne groups are involved in the crosslinking reaction via the trimerization reaction of the conjugated alkynyl groups and the Diels–Alder reaction. Furthermore, thermal properties of the polybenzoxazine are studied by dynamic thermomechanical analysis and thermogravimetric analysis. A glass‐transition temperature (T_gs) of as high as 412 °C and a char yield of 75.6% at 800 °C under nitrogen are obtained with the aid of the conjugated alkyne groups. Its excellent heat resistance dominates most thermosetting resins and will serve for heat shields. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1587–1592     

Bulk and shear rheology of silica/polystyrene nanocomposite: Reinforcement and dynamics

Bulk and shear rheological studies were performed on a 10 wt % silica nanoparticle‐filled polystyrene nanocomposite. The limiting moduli in glassy and rubbery states are higher for the nanocomposite than for the neat polymer; the increase is consistent with hydrodynamic reinforcement and is slightly higher than the lower bound of the rule of mixtures prediction. All evidence indicates that the presence of nanoparticles does not significantly change the polymer dynamics associated with glass transition, except to increase the T_g by 3 K. Comparison of the bulk and shear retardation spectra suggests that the underlying mechanisms for both responses are similar at short times and that the long‐time chain modes available to the shear are not available to the bulk, consistent with Plazek's earlier findings. In addition, T ? T_g and TV^γ scaling, along with the findings of thermorheological complexity, are discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 621–632