Influence of modified light dispersion theory on fermion tunneling radiation in the Einstein-Maxwell-dilaton-axion black hole

Based on a light dispersion relationship derived from string theory and quantum gravitational theory,we make an accurate modification to the quantum tunneling radiation rate and black hole temperature at an event horizon in a stationary axial-symmetric Einstein–Maxwell–dilaton–axion black hole.We also analyze our new results and carry out some significant discussions.This work enriches the research content and methods of the frontiers of black hole physics.     

超导腔数字自激垂直测试系统

基于数字自激算法设计并实现的超导腔垂直测试系统提高了超导腔的垂直测试效率,为先进光源技术研发与测试平台(PAPS)的超导腔批量化生产提供了重要保障;垂直测试系统的射频前端和时钟分配系统采用了二次上下变频方案,可以在一定范围内灵活设置测试系统自激环路的工作频率,增大了该测试系统的工作带宽。利用此系统完成了1.3 GHz 9-cell超导腔的通带频率测试,结果表明,该测试系统能有效避免不同模式之间的串扰,具备较强的频率分辨能力(<800 kHz),保证多单元超导腔性能验证的进行。     

脉冲跨周期调制连续导电模式Buck变换器低频波动现象研究

揭示了脉冲跨周期调制(pulse skipped modulation,PSM)电感电流连续导电模式(continuous conduction mode,CCM)Buck变换器中存在的低频波动现象,分析了PSM调制CCM Buck变换器的能量转换过程,阐述了低频波动的产生机理,给出了低频波动的判断条件.建立了PSM调制CCM Buck变换器的同步开关映射模型,基于该模型给出了电感电流与输出电压随输出电容等效串联电阻(equivalent series resistance,ESR)变化的分岔图,分析了ESR对低频波动的影响.为消除PSM调制CCM Buck中存在的低频波动,提出了电容电流脉冲跨周期调制(capacitor current pulse skipped modulation,CC-PSM)方法.研究结果表明:在ESR较小时,CC-PSM调制CCM Buck变换器消除了PSM调制CCM Buck变换器存在的低频波动.仿真与实验结果验证了理论分析的正确性.     

Fe~(2+)-邻菲罗啉分光光度法测定针剂中头孢他啶

基于头孢他啶将Fe3+还原为Fe2+,生成的Fe2+与邻菲罗啉形成红色配合物,建立了Fe2+-邻菲罗啉分光光度法测定头孢他啶的新方法,头孢他啶标准溶液浓度在0.4—10mg/L范围内与吸光度呈线性关系,线性回归方程为ΔA=0.1008C(mg/L)+0.07789,线性相关系数r=0.9970。该法用于针剂中头孢他啶的含量分析,结果满意。     

应用熔石英棒相位共轭镜的LD泵浦激光MOPA系统

 用熔石英棒作为相位共轭镜材料,在LD泵浦的激光MOPA系统中实现了在 100和400 Hz下的受激布里渊散射相位共轭。实验测得重复频率100 Hz时双通放大后的x和y方向的光束质量平方因子分别为1.74和1.66,最大反射率达到24.33% ,脉冲宽度从60 ns压缩到31.34 ns。重复频率400 Hz时双通放大后的x和y方向的光束质量平方因子分别为2.10和2.12,脉冲宽度从56.69 ns压缩到28.84 ns。     

Degradation of 5-Dialkylamino-Substituted Chlorsulfuron Derivatives in Alkaline Soil

Sulfonylurea herbicides are widely used as acetolactate synthase (ALS) inhibitors due to their super-efficient activity. However, some sulfonylurea herbicides show toxicity under crop rotation due to their long degradation time, for example, chlorsulfuron. Our research goal is to obtain chlorsulfuron-derived herbicides with controllable degradation time, good crop safety and high herbicidal activities. Based on our previously reported results in acidic soil, we studied the degradation behaviors of 5-dialkylamino-substituted chlorsulfuron derivatives (NL101–NL108) in alkaline soil (pH 8.39). The experimental data indicate that addition of the 5-dialkylamino groups on the benzene ring of chlorsulfuron greatly accelerated degradation in alkaline soil. These chlorsulfuron derivatives degrade 10.8 to 51.8 times faster than chlorsulfuron and exhibit excellent crop safety on wheat and corn (through pre-emergence treatment). With a comprehensive consideration of structures, bioassay activities, soil degradation and crop safety, it could be concluded that 5-dialkylamino-substituted chlorsulfuron derivatives are potential green sulfonylurea herbicides for pre-emergence treatment on both wheat and corn. The study also provides valuable information for the discovery of new sulfonylurea herbicides for crop rotation.     

Alkaline Soil Degradation and Crop Safety of 5-Substituted Chlorsulfuron Derivatives

Sulfonylurea herbicides can lead to serious weed resistance due to their long degradation times and large-scale applications. This is especially true for chlorsulfuron, a widely used acetolactate synthase inhibitor used around the world. Its persistence in soil often affects the growth of crop seedlings in the following crop rotation, and leads to serious environmental pollution all over the world. Our research goal is to obtain chlorsulfuron-derived herbicides with high herbicidal activities, fast degradation times, as well as good crop safety. On account of the slow natural degradation of chlorsulfuron in alkaline soil, based on the previously reported results in acidic soil, the degradation behaviours of 5-substituted chlorsulfuron analogues (L101–L107) were investigated in a soil with pH 8.39. The experimental data indicated that 5-substituted chlorsulfuron compounds could accelerate degradation rates in alkaline soil, and thus, highlighted the potential for rational controllable degradation in soil. The degradation rates of these chlorsulfuron derivatives were accelerated by 1.84–77.22-fold, compared to chlorsulfuron, and exhibited excellent crop safety in wheat and corn (through pre-emergence treatment). In combination with bioassay activities, acidic and alkaline soil degradation, and crop safety, it was concluded that compounds L104 and L107, with ethyl or methyl groups, are potential green sulfonylurea herbicides for pre-emergence treatment on wheat and corn. This paper provides a reference for the further design of new sulfonylurea herbicides with high herbicidal activity, fast, controllable degradation rates, and high crop safety.     

Color-tunable and Highly Emissive Solid Materials Constructed from Tetraphenylethylene-o-carborane-based Building Blocks: Synthesis,Aggregation-induced emission,and Photophysics

A novel kind of expanded tetraphenylethylene (TPE)-carborane-TPE pentad has been synthesized by using two adjacent carborane moieties as central bridges and three TPE units in lateral positions. Its solid-state fluorescence quantum yield was substantially increased to 68.2% by expanding the number of bridges between carborane and TPE. Subsequently, the emission color shifted from blue to orange-yellow (126 nm). Mechanical insights into the electronic structure of the extended TPE-carborane-TPE pentads were obtained from density functional theory (DFT) calculations.     

De Novo and Divergent Synthesis of Highly Functionalized Furans by Cascade Reactions of 2-Hydroxy-1,4-diones with Nucleophiles

Herein, a divergent synthesis of a variety of 2α- and 5α-substituted furan derivatives from 2-hydroxy-1,4-diones is reported. By using appropriate substrates and an acid catalyst, the reactions occurred selectively through cyclization/1,6-conjugate addition or cyclization/Friedel–Crafts-type cascade reactions. A broad range of nucleophilic reagents (>10 types for the 1,6-conjugate addition for 5α substitution and >20 types for the Friedel–Crafts-type cascade reaction for 2α substitution), including alcohols, amides, furan, thiophene, pyrrole, indole, phenols, and many others, can successfully participate in the reactions, providing a universal strategy for a diversity-oriented synthesis of α-substituted furan derivatives. Deuteriation experiments and DFT calculations were carried out to support the proposed reaction mechanisms. Antifungal activity experiments revealed that products with an indole or 4-hydroxycoumarin core substituted at the 2α position showed moderate activities against Rhizoctorzia solani and Botrytis cinerea, respectively.     

中国大陆西部强震前超低频磁场时空变化特征

对2015年至2019年期间中国大陆西部的磁通门磁力仪秒采样观测资料开展了5—100 s频段的地磁垂直强度极化分析，并运用一些数学方法对分析结果进行了处理。结果显示，极化高值在经向和纬向均无明显的形态和幅值变化，且极化高值与地磁外源场扰动无关。在此基础上筛选出18次极化高值异常事件，利用插值方法得到了极化高值异常的空间分布图，并分析了18次高值异常与中国大陆西部及周边15次强震的时空关系。分析结果表明：地磁场出现多台同步极化高值现象后的半年内，高值区可能发生M6.0以上强震；高值现象出现后，多个高值区均有可能发生强震；后续强震的震级与高值区面积呈正相关。