Simulation study of a photo-injector for brightness improvement in Thomson scattering X-ray source via ballistic bunching

Increasing the peak brightness is beneficial to various applications of the Thomson scattering X-ray source. A higher peak brightness of the scattered X-ray pulse demands a shorter scattering electron beam realized by beam compression in the electron beam-line. In this article, we study the possibility of compressing the electron beam in a typical S-band normal conducting photo-injector via ballistic bunching, through just adding a short RF linac section right behind the RF gun, so as to improve the peak brightness of the scattered x-ray pulse. Numerical optimization by ASTRA demonstrates that the peak current can increase from 50 A to > 300 A for a 500 pC, 10 ps FWHM electron pulse, while normalized transverse RMS emittance and RMS energy spread increases very little. Correspondingly, the peak brightness of the Thomson scattering X-ray source is estimated to increase about three times.     

R134a/R125混合工质管外沸腾换热特性研究

对水平管外纯R134a和三种不同浓度的R134a/R125混合工质池沸腾换热性能进行了试验研究。在试验研究的基础上对二元混合工质的沸腾换热进行理论分析,并提出了二元混合工质的沸腾换热预测关联式。在实验范围内,实验值与预测值的最大偏差不超过±20%,可以满足工程应用的需要。     

基于红外标准星的红外辐射标校方法

为了提高空间目标的红外辐射测量准确度,提出了基于精确校准的红外标准星的红外辐射标校方法.测量不同大气质量处多颗具有较高光谱分辨率的红外标准星,采用天文孔径测光法对望远镜拍星数据进行处理,依据大气消光模型进行最小二乘线性拟合,获得了测量系统的红外辐射响应率和大气消光.1.2m望远镜上中波红外成像终端验证性实验结果表明,该方法的恒星辐照度反演误差最大为16.28%.且该方法无需增加额外设备,操作简单,易于实现,可随时对测量设备进行实时标校.对地基大口径望远镜的红外辐射测量具有一定的应用价值.     

钴（III）咔咯合成与应用研究进展

综述了不同类型咔咯自由碱及其金属钴（III）配合物的合成方法，并分类探讨了不同类型的金属钴（III）咔咯在能源化学与环境化学领域的应用，包括（1）电化学催化氧气还原；（2）分子传感器；（3）有机氯污染物降解；（4）烯烃催化氧化。同时，对钴（III）咔咯化学未来的发展方向进行了展望。     

HIF-1α及 VEGF 在类风湿关节炎成纤维样滑膜细胞中的表达及意义

目的研究类风湿性关节炎（RA）患者滑膜细胞在体外常氧和缺氧培养条件下缺氧诱导因子-1α（HIF-1α）和血管内皮生长因子（VEGF）表达的差异性及意义。方法对RA患者及骨关节炎（OA）患者的关节滑膜细胞在体外常氧和缺氧条件下分别进行培养,根据培养条件分为常氧组、缺氧6h组及缺氧12h组;采用免疫印迹法分别检测各组成纤维样滑膜细胞的HIF-1α及VEGF的表达情况。结果与常氧组相比,缺氧6h及12h的RA和OA患者滑膜细胞的HIF-1α及VEGF的表达均显著增加,差异均有统计学意义（均P＜0.05）。同时RA和OA患者缺氧12h组滑膜细胞HIF-1α及VEGF的表达高于缺氧6h组,差异均有统计学意义（均P＜0.05）。RA和OA患者3组滑膜细胞的HIF-1α及VEGF的表达均呈正相关（均P＜0.05）。常氧组RA与OA患者滑膜细胞的HIF-1α及VEGF的表达均无统计学差异（均P＞0.05）;而缺氧6h和12h组中RA滑膜细胞HIF-1α及VEGF的表达均高于OA滑膜细胞,差异均有统计学意义（均P＜0.05）。结论在缺氧条件下RA患者滑膜细胞HIF-1α及VEGF表达显著升高且密切相关,可能缺氧-HIF-1α-VEGF这一信号途径在RA的发生、发展中起着重要作用。     

大口径望远镜波像差的外场检验方法

为在外场环境下对大口径望远镜进行系统波像差的检验,研制了一套具有高探测能力的Shack-Hartmann波前传感器.利用恒星作为光源,对口径1 m、焦距11 m的大口径望远镜进行了波像差检验实验,测量结果为系统波像差在0.39λ~ 0.46λ RMS之间,且随着俯仰角的增加而增大,主要像差形式为3阶0°像散,与星点检验的结果一致.     

长焦距超高倍率变焦距光学系统设计

为设计一套焦距17～1 700mm的长焦距、超高倍率变焦距光学系统,首先在合理选择初始结构基础上,通过比较高斯光学计算结果找出高斯解对系统性能的影响规律,从而确定系统的关键参量;然后通过分析各组元相对孔径和像差特点选定结构形式,并进行系统像差的校正和优化.设计结果系统光学总长760mm,各焦距位置全视场50lp/mm处MTF>0.3,各项指标满足系统要求.     

气相色谱-质谱法测定香椿皮中脂溶性成分

香椿皮样品经乙醇提取后用硅胶柱净化,所得洗脱液中脂溶性成分用气相色谱-质谱法分离和鉴定,用归一化法测定其相对含量。共鉴定出41种化学成分,其含量占总脂溶性成分峰面积的91.99%。主要脂溶性成分及其含量为萜烯类(36.58%)、烷烃类(31.70%)和脂肪酸类(21.95%)。     

保险人投资策略与破产的关系

本文主要考虑带投资收益的风险模型,在该模型下保险人可以根据盈余投资,投资的数量为时间t的函数,我们得到保险人投资策略与破产概率与t时刻所满足的积分-微分方程.     

Proton loss of inner radiation belt during geomagnetic storm of 2018 based on CSES satellite observation

The proton distribution in inner radiation belt is often affected by strong geomagnetic storm disturbance. Based on the data of the sun-synchronous CSES satellite, which carries with several high energy particle payloads and was launched in February 2018, we analyzed the extensive proton variations in the inner radiation belt in a wide energy range of 2 MeV-220 MeV during 2018 major geomagnetic storm. The result indicates that the loss mechanism of protons was energy dependence which is consistent with some previous studies. For protons at low energy 2 MeV-20 MeV, the fluxes were decreased during main phase of the storm and did not come back quickly during the recovery phase, which is likely to be caused by Coulomb collision due to neutral atmosphere density variation. At higher energy 30 MeV-100 MeV, it was confirmed that the magnetic field line curvature scattering plays a significant role in the proton loss phenomenon during this storm. At highest energies > 100 MeV, the fluxes of protons kept a stable level and did not exhibit a significant loss during this storm.