植物RNA修饰的功能及分析方法

除经典碱基外, RNA中还包含许多化学修饰.迄今,已经在生命体的三域系统中鉴定出超过150种RNA修饰类型.这些RNA修饰不改变RNA的序列,但会改变其结构和生化特性,从而调节基因的时空表达. RNA修饰作为表观遗传学研究的一个重要领域,在调控植物的生长发育和胁迫应激中起到至关重要的作用.近年来,随着分析技术,特别是RNA修饰测序技术的不断进步,对植物RNA修饰的功能和机制获得了深入的认识.本文主要介绍了植物RNA修饰的功能,总结了针对这些植物中RNA修饰的分析方法,以便为今后系统地开展植物中RNA修饰的研究提供参考.     

Time constant optimization of solar irradiance absolute radiometer

We experimentally evaluate and optimize the time constant of solar irradiance absolute radiometer (SIAR). The systemic error introduced by variable time constant is studied by a finite element method. The results shown that, with a classic time constant of 30 s for SIAR, the systemic errors are 0.06% in the midday and 0.275% in the morning and afternoon. The uncertainty level which can be considered negligible for SIAR is also investigated, and it is suggested that the uncertainty level has to be less than 0.02%. Then, combining the requirement of international comparison with these two conclusions, we conclude that the suitable time constant for SIAR is 20 s. Thiswork has been supported by the National Natural Science Foundation of China (No.41474161), and the National High Technology Research and Development Program of China (No.2015AA123703). E-mail:tanggxiao1022@126.com      

新型2,4-二羟基蝶啶类衍生物的合成及其抗肿瘤活性

蝶啶类化合物的抗肿瘤活性是研究最多,也是最具有治疗潜力的一类化合物。以Ibrutinib为先导化合物,以4-氨基-2,6-二羟基嘧啶为原料出发,经过多步首次合成了新型2,4-二羟基蝶啶类衍生物,并对其进行了¹H NMR、¹³C NMR和MS(ESI)的表征。选用A549细胞做了抗肿瘤实验,结果表明：化合物5h,5j和6o在低浓度下表现出小于10%的抑制率,在高浓度下均有大于20%的抑制率,说明5h,5j和6o对A549细胞有一定的抑制效果。     

International comparison of the SIAR measurement and the WRR standard

We experimentally compare the solar irradiance absolute radiometer (SIAR) measurement with the world radiometric reference (WRR) standard to improve the accuracy of instrument. The SIAR joined in the international pyrheliometer comparison (IPC) in 2000. The comparison results show that the calibration factors for SIAR to WRR are 0.999 220, 1.001 694, 0.998 334 and 0.997 439 in the 9th IPC, the 10th IPC, the 11th IPC and the 12th IPC, respectively. These results are added to the measurement uncertainty budget of SIAR. The repeatability of the SIAR-type absolute radiometers is also investigated. The relative error introduced by two SIAR-type absolute radiometers is within 0.25%.     

双极性直线型变压器驱动源的研制

针对双极性脉冲电压介质阻挡放电（DBD）的应用需求,提出了一种基于直线型变压器驱动源（LTD）的全固态双极性纳秒脉冲形成拓扑。脉冲产生期间各开关的驱动电路均可靠共地极大降低了高低压隔离需求,因此与传统单极性LTD一样理论上可实现脉冲子模块的无限制叠加以获得更高电压的双极性脉冲输出。各脉冲子模块上集成数量相等但具有相反电压极性的储能电容,使隔离磁心的励磁电流在不同脉冲极性下正负交变,有效提高了磁心的利用率,不再需要设置专门的磁通复位电路。最后研制了一套模块化紧凑型双极性LTD原理验证样机,可输出脉冲参数为:电压幅值0～±2 kV,脉冲电流80 A,脉冲宽度50～200 ns,所有脉冲参数可通过上位机灵活可调,通过增加LTD子模块数量可获得更高的脉冲电压。