激光脉冲形状对弓形波电子俘获的影响

使用二维粒子模拟程序研究了电子弓形波注入机制中激光脉冲形状对电子俘获效果的影响. 研究结果表明, 激光脉冲时间上升沿陡峭的正扭曲脉冲激发的尾波场强度高, 加速区域分布广, 并且有利于电子获得更高的初速度, 从而推动更多的电子进入尾波场加速相位. 在其他条件相同的情况下, 正扭曲脉冲的电子俘获数目远高于激光脉冲时间分别为高斯形和负扭曲分布的情形, 使得电子束的品质得到改善. 研究结果对于理解尾波场加速中电子注入过程以及获得大电荷量高能电子束具有积极意义. 关键词： 尾波场 电子俘获 时间波形 粒子模拟     

One-pot synthesis of one-dimensional array Pt nanoparticles on carbon nanotubes via a facile microwave polyol method

High-density attachment and one-dimensional array Pt nanoparticles (NPs) on carbon nanotubes (CNTs) to generate Pt/CNTs heterostructures are obtained via one-pot microwave polyol method. The morphology, composition of as-obtained Pt/CNTs heterostructures is characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD). The Raman spectrum and Fourier transform infrared (FTIR) spectrum show the introduction of defects or functional groups on CNTs surface, which are crucial factors to assist the nucleation and growth of Pt NPs along the skeleton of CNTs.     

The Biological Fate of a Novel Anticancer Drug Candidate TNBG-5602: Metabolic Profile,Interaction with CYP450, and Pharmacokinetics in Rats

TNBG-5602, a novel anticancer drug candidate, may induce the expression of PPARγ, causing targeted lipotoxicity in cancer tissues. In this study, the in vivo metabolism in rats, in vitro metabolism in recombinant cytochromes, molecular docking for the CYP binding site, and pharmacokinetics in rats were explored to better understand TNBG-5602′s in vivo fate and behavior. Thirteen metabolites were identified using a high-resolution mass spectrometry method, and metabolizing pathways of TNBG-5602 were proposed. Results suggest that TNBG-5602 could be metabolized by CYP450s, while CYP2D6 may play an important role in its in vivo metabolism. The main metabolizing sites of TNBG-5602 are the amino group on the side chain and rings A and E in the molecule. TNBG-5602 is a potent CYP2D6 inhibitor, with an IC₅₀ value of 2.52 μM. An interaction responsible for its metabolism is formed by the NH on the side chain bonding with the ASP301 on the CYP2D6. The pharmacokinetics in rats after a single intravenous administration were fitted to a two-compartment model. The clearance was 0.022 L min⁻¹, and the elimination half-life was 710.9 min. The distribution volume of the peripheral compartment was 1.88-fold that of the central compartment, while the K₁₂ was 1.5-fold that of K₂₁. In conclusion, these studies have not only revealed the metabolizing pathways of TNBG-5602 using in vivo and in vitro methodology, but they have also provided the pharmacokinetic characteristics of TNBG-5602 in rats. The results suggest that TNBG-5602 has good drug developability in terms of pharmacokinetic behaviors.     

超声波辅助-活性炭富集-火焰原子吸收光谱法测定岩石矿物中的金

在战略性性矿产资源中,金一直都是极其紧缺且重要的元素。目前岩石矿物测定金使用较广泛的方法主要为火试金重量法、活性炭富集-原子吸收光谱法。然而这两种方法分析步骤都比较繁琐,受环境条件影响大,测样周期长,不适合大批量分析测试任务。本文通过超声波辅助,基于超声空化效应,活性炭在超声空化所产生的局部高温、高压、冲击波、微射流等加强传质作用下,能快速高效地对样品中的金离子进行富集的原理,建立一种独特的活性炭富集方法,改进过滤方式,运用火焰原子吸收光谱仪测定金的新方法。通过对9个金矿石成分标准物质GBW(E)070012a、GBW07807a、GBW07808b、GBW07300a、GBW07809b、GBW07297a、GBW07298a、GBW07299a、GBW07810进行实验对比分析,优化方法中活性炭用量,超声波频次与功率、时间、溶液温度等实验条件。研究确定活性炭用量为0.5g后金的回收率趋于稳定;超声波频次和时间设定为100kHZ,20min不仅测定数据准确且能较大幅度缩短工作时间;溶液温度控制在20℃为宜。在优化条件下,方法验证测定得出金的质量浓度在0~20mg/L范围内校准曲线方程为Abs=0.01958K+0.000642,相关系数（R2）为1.0000,以金矿石标准物质GBW(E)070012a平行测定12次计算得出方法检出限（MDL）为0.02248ug/g;以GBW07807a等8个金矿石标准物质进行精密度和正确度方法实验,相对误差（RE）为0.23%~1.50%,相对标准偏差（RSD）为0.43%~3.65%。与国家标准方法进行比对实验,实验证明新方法满足岩石矿物中金的分析要求。     

Rapid Discrimination and Prediction of Ginsengs from Three Origins Based on UHPLC-Q-TOF-MS Combined with SVM

Ginseng, which contains abundant ginsenosides, grows mainly in the Jilin, Liaoning, and Heilongjiang in China. It has been reported that the quality and traits of ginsengs from different origins were greatly different. To date, the accurate prediction of the origins of ginseng samples is still a challenge. Here, we integrated ultra-high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) with a support vector machine (SVM) for rapid discrimination and prediction of ginseng from the three main regions where it is cultivated in China. Firstly, we develop a stable and reliable UHPLC-Q-TOF-MS method to obtain robust information for 31 batches of ginseng samples after reasonable optimization. Subsequently, a rapid pre-processing method was established for the rapid screening and identification of 69 characteristic ginsenosides in 31 batches ginseng samples from three different origins. The SVM model successfully distinguished ginseng origin, and the accuracy of SVM model was improved from 83% to 100% by optimizing the normalization method. Six crucial quality markers for different origins of ginseng were screened using a permutation importance algorithm in the SVM model. In addition, in order to validate the method, eight batches of test samples were used to predict the regions of cultivation of ginseng using the SVM model based on the six selected quality markers. As a result, the proposed strategy was suitable for the discrimination and prediction of the origin of ginseng samples.     

Enhanced extraction of cleistanthol from Phyllanthus flexuosus by deep eutectic solvent-modified anion-exchange resin

Anion-exchange resin (AER) and choline chloride-based deep eutectic solvent-modified anion-exchange resin (DES-AER) were prepared, and their performance properties were assessed by Fourier transform infrared spectrometer (FTIR), field emission scanning electron microscopy (FE-SEM), and adsorption experiments. In addition, the separation characteristics on the solid-phase extraction (SPE) cartridges packed with octadecyl silica (ODS), AER, and DES-AER for rapid extraction of cleistanthol from Phyllanthus flexuosus extracts have been evaluated, with recoveries of the materials tested at 72.14, 68.21, and 82.11%, respectively. All results demonstrated that DES-AER not only offered higher adsorption capacity for cleistanthol but also exhibited better extraction efficiency of cleistanthol than those of ODS and AER. In this work, it is the first application of DES in the modification of AER, and the proposed DES-AER showed significant affinity and selectivity toward cleistanthol, which could have potential application for natural product extraction.     

Release of the Water Molecule Encapsulated Inside an Open‐Cage Fullerene through Hydrogen Bonding Mediated by Hydrogen Fluoride

A reversible wetting/dewetting procedure is reported for an open‐cage fullerene with an 18‐membered orifice. In a homogeneous mixture of H₂O/EtOH/CHCl₃, water was encapsulated into the cavity of the open‐cage compound quantitatively at 80 °C. Addition of aqueous hydrogen fluoride into the water‐encapsulated complex removed the encapsulated water completely at room temperature. H‐bonding between the trapped water and fluoride is shown to play a key role for the water release process.     

AgInSbTe薄膜的短波长记录性能分析

采用自制的装置研究了Ag5In5Sb47Te33薄膜的静态记录性能与记录激光的功率和脉冲宽度的关系，并对其记录畴形貌特点进行了直接观察。结果表明只有记录激光的功率和脉冲宽度在一定范围之内才能起到信息记录的作用，所得的记录畴形貌十分清晰，基本为非晶态Ag5In5Sb47Te33；小于该范围的激光能量不能使材料结构发生较大的变化，所得的记录畴形貌模糊，反射率对比度低于2％；大于该范围所得的记录畴由烧蚀区和其周围的非晶态Ag5In5Sb47Te33组成。另外，得到了记录激光功率为12mW、脉冲宽度为90ns的Ag5In5Sb47Te33薄膜的短波长最佳记录条件，其记录畴的反射率对比度为22％，直径为380nm-400nm。