加速溶剂萃取-气相色谱法测定土壤中的有机磷农药

采用加速溶剂萃取-气相色谱法测定土壤中有机磷农药。土壤样品与无水硫酸钠混合后,再加适量中性氧化铝和活性碳,用丙酮-二氯甲烷在加速溶剂萃取仪土于10．3MPa、60℃条件下提取10min,用FPD检测器进行分析：土壤中7种有机磷农药的回收率为85．5％～102．7％,测定结果的相对标准偏差为5．7％～13．0％（n=6）,检出限为0．03～0．07μg/kg。该法具有良好的分离效果、较宽的线性关系和较高的灵敏度。     

OJ手性柱分离芳基烷酸类非甾体解热镇痛药的色谱保留特性和拆分机理

使用纤维素类手性柱OJ柱, 分离布洛芬、依托度酸、非诺洛芬钙、酮洛芬、洛索洛芬等5个芳基烷酸类非甾体解热镇痛药对映体, 并通过溶质计量置换保留模型和热力学研究对OJ手性柱手性分离机理进行探讨. 结果表明, OJ手性柱可在正相条件下分离系列芳基烷酸类非甾体解热镇痛药, 对映体的色谱保留和分离度可以通过改变流动相中醇类置换剂和浓度、有机酸性改性剂和浓度、柱温等因素调节.     

联萘酚多氢键硫脲催化合成1,4-二氢吡啶衍生物

本文合成了三种具有多氢键的联萘酚轴手性硫脲催化剂,并将其用于催化合成1,4-二氢吡啶衍生物。结果显示,所合成的新型多氢键硫脲均表现出较好的催化作用,能有效地提高1,4-二氢吡啶衍生物的收率和对映选择性。所有新化合物结构均经过¹H NMR、¹³C NMR、IR、熔点等表征所确认。     

应用极化水分子模型研究单分子层受限水的介电性质

受限条件下水的介电性质因测量极具挑战,其在诸多电化学过程与反应输运过程中如何扮演关键角色从未被定量地澄清.本工作利用平衡态分子动力学模拟和受限体系介电性质计算方法,系统性地探索了0.65 nm限域尺寸、5×10⁸ Pa限域压强、不同温度条件下单分子受限冰和受限水的介电性质.详细比较了恒定偶极矩SPC/E水分子模型和可极化的SWM4-NDP水分子模型在描述受限冰、水结构与介电性质上的优劣势,包括统计分析SWM4-NDP模型模拟的单分子层受限水和受限冰的瞬时分子偶极矩概率密度分布,计算每个模拟体系的静态结构因子、静态偶极空间关联函数、静态介电常数、体系偶极时间关联函数和德拜弛豫时间.首次发现了极化水分子模型描述的低维度受限水和受限冰的奇异分子极性变化,并观察到两种模型描述静态结构性质的效果相当, SWM4-NDP模型对于静态介电常数描述的优势会因受限条件的增强而被大幅削减.但在受限水介电极化弛豫动力学性质描述上SWM4-NDP模型明显优于SPC/E模型.我们推断SWM4-NDP模型在探索受限水结构相变动力学以及受限体系离子输运和溶剂化动力学等过程的模拟研究中是比SPC...     

绿色单体二氧化碳参与的新型聚合反应

二氧化碳(CO₂)是一种丰富、廉价、无毒以及可再生的一碳资源,也是一种可用于聚合的绿色单体.基于CO₂的聚合是近年来的研究热点之一.目前广泛报道的是CO₂和环氧单体的聚合反应,经过几十年的发展已经成功实现工业化生产.最近几年,一些CO₂参与的新型聚合反应被陆续报道,这些工作大都通过两种途径实现从CO₂到高分子材料的转变.第一个途径是先将CO₂转化为可以聚合的单体,例如:内酯、环状碳酸酯和2,5-二呋喃甲酸等,再利用开环或者逐步聚合将单体转化为聚合物;另一个途径是直接以CO₂为单体和其他类型单体共聚得到聚合物.这两种途径对于发展CO₂参与的新型聚合反应,拓展CO₂基聚合物种类都具有重要意义.本综述按照CO₂直接还是间接参与聚合反应分类总结了近年来在CO₂制备高分子材料方面的进展,并对未来发展方向进行了简单阐述.     

空间-时间分数阶对流扩散方程的数值解法

本文考虑一个空间-时间分数阶对流扩散方程.这个方程是将一般的对流扩散方程中的时间一阶导数用α(0＜α＜1)阶导数代替,空间二阶导数用β(1＜β＜2)阶导数代替.本文提出了一个隐式差分格式,验证了这个格式是无条件稳定的,并证明了它的收敛性,其收敛阶为O(ι h).最后给出了数值例子.     

Entropy Sources Based on Silicon Chips: True Random Number Generator and Physical Unclonable Function

Entropy is a measure of uncertainty or randomness. It is the foundation for almost all cryptographic systems. True random number generators (TRNGs) and physical unclonable functions (PUFs) are the silicon primitives to respectively harvest dynamic and static entropy to generate random bit streams. In this survey paper, we present a systematic and comprehensive review of different state-of-the-art methods to harvest entropy from silicon-based devices, including the implementations, applications, and the security of the designs. Furthermore, we conclude the trends of the entropy source design to point out the current spots of entropy harvesting.     

Ultrasound Treatment Enhanced Semidry-Milled Rice Flour Properties and Gluten-Free Rice Bread Quality

The structural and functional properties of physical modified rice flour, including ultrasound treated rice flour (US), microwave treated rice flour (MW) and hydrothermal treated rice flour (HT) were investigated with wet-milled rice flour (WF) used as a positive control. The results showed the presence of small dents and pores on the rice flour granules of US and MW while more fragments and cracks were showed in HT. XRD and FTIR revealed that moderate ultrasonic treatment promoted the orderly arrangement of starch while hydrothermal treatment destroyed the crystalline structure of rice flour. In addition, the significant decrease of gelatinization enthalpy and the narrowing gelatinization temperature were observed in US. Compared to that of SF, adding physical modified rice flour led to a batter with higher viscoelasticity and lower tan δ. However, the batter added HT exhibited highest G′ and G″ values and lowest tan δ, which led to a harder texture of bread. Texture analysis demonstrated that physical modified rice flour (except HT) reduced the hardness, cohesion, and gumminess of rice bread. Especially, the specific volume of bread with US increased by 15.6% and the hardness decreased by 17.6%. This study suggested that ultrasound treatment of rice flour could improve texture properties and appearance of rice bread.     

Separation and Purification of Two Saponins from Paris polyphylla var. yunnanensis by a Macroporous Resin

An effective method for separating and purifying critical saponins (polyphyllin II and polyphyllin VII) from a Paris polyphylla var. yunnanensis extract was developed in this study which was environmentally friendly and economical. Static adsorption kinetics, thermodynamics, and the dynamic adsorption-desorption of macroporous resins were investigated, and then the conditions of purification and separation were optimized by fitting with an adsorption thermodynamics equation and a kinetic equation. Effective NKA-9 resin from seven macroporous resins was screened out to separate and purify the two saponins. The static adsorption and dynamic adsorption were chemical and physical adsorption dual-processes on the NKA-9 resin. Under the optimum parameters, the contents of polyphyllin II and polyphyllin VII in the product were 17.3-fold and 28.6-fold those in plant extracts, respectively. The total yields of the two saponins were 93.16%. This research thus provides a theoretical foundation for the large-scale industrial production of the natural drugs polyphyllin II and polyphyllin VII.     

Qualitative Analysis of Multiple Phytochemical Compounds in Tojapride Based on UHPLC Q-Exactive Orbitrap Mass Spectrometry

Tojapride is composed of Caulis Perillae, Rhizoma Cyperi, Radix Glycyrrhizae, Citrus aurantium L., Coptis chinensis Franch, Pericarpium Citri Reticulatae, Reynoutria japonica Houtt, Tetradium ruticarpum, and Cleistocactus sepium. It has the effects of inhibiting gastric acid and relieving pain. It is clinically used for treating gastroesophageal reflux disease. To further study the pharmacodynamic properties of Tojapride, the systematic characterization of the chemical constituents in Tojapride was investigated using ultra-performance liquid chromatography with Q-Exactive Orbitrap mass spectrometry combined with parallel reaction monitoring for the first time. Eventually, a total of 222 compounds, including flavonoids, alkaloids, and glycyrrhizic acid derivatives, were identified based on the chromatographic retention times, MS/MS² information, and bibliography data; a total of 218 of these were reported for the first time as being present in Tojapride. This newly developed approach provides a powerful tool for extending our understanding of chemical constituents of Tojapride, which can be further extended to other TCMP composition research.