Overloading control of gas chromatographic systems

Increasing the interlaboratory reproducibility of gas chromatographic retention indices requires avoiding measurements distorted by overloading effects. Several criteria of evaluating the limits of the mass overloading of gas chromatographic systems are compared and reconsidered. The criteria mostly appropriate for practical purposes are based on (i) the dependences of factors of peak broadening (ratio of peak height and its width) vs. amount of analyte injected into the chromatographic column and (ii) the dependence of parameters characterizing the peak distortion (asymmetry factor) vs. the amount of analyte. Both these criteria provide mutually comparable evaluations of the overloading limits for analytes of different polarity. At the same time, the dependence of retention indices vs. amounts of analyte injected in the chromatographic column cannot be recommended for overloading control, because the parameters of the corresponding linear regressions indicate temperature dependence. The interpretation of certain gas chromatographic anomalies requires the correct evaluation of overloading limits. For example, the unusual temperature dependence of retention indices of polar analytes on non‐polar stationary phases and the dependence of retention indices on ratio of amounts of target analytes and reference compounds.     

Development of a method using high‐performance liquid chromatographic fingerprint and multi‐ingredients quantitative analysis for the quality control of Yangxinshi Pian

A simple and reliable method of high‐performance liquid chromatography with diode array detection method was developed for fingerprint analysis and simultaneous determination of six compounds including puerarin, salvianolic acid B, berberine hydrochloride, palmatine chloride, dehydrocorydaline, and icariin in the Chinese medicine preparation Yangxinshi Pian. The separation was performed on an Agilent Eclipse XDB‐C₁₈ reserved‐phase column (250 mm × 4.6mm I.D., 5 μm) using gradient elution with 50 mmol/L monopotassium phosphate aqueous solution and methanol as mobile phase at a flow rate of 1.0 mL/min. The column operating temperature was set at 30°C, and the detection wavelength was 280 nm. The method was validated by linearity, precision, accuracy, stability, and recovery. For fingerprint analysis, 25 peaks were selected as the common peaks, and four kinds of similarities including cosine similarity (S), ratio of similarity (S′), projection content similarity (C), and content similarity (P) were applied to evaluate the quality consistency of different batches of Yangxinshi Pian. The results showed that the developed method was an efficient tool for quality evaluation of Yangxinshi Pian.     

An ultra-wideband coding polarizer for beam control and RCS reduction

Pancharatnam−Berry (PB) phase metasurface, as a special class of gradient metasurfaces, has been paid much attention owing to the robust performance for phase control of circularly polarized waves. Herein, we present an element-based polarizer for the first step, which enables the incident electromagnetic waves into the cross-polarized waves with the relative bandwidth of 71%, and the polarization conversion ratio exceeds 90% at 6.9−14.5 GHz. Then an eight-elements coding polarizer based on the PB phase is presented for the applications on beam control and radar cross section reduction. The simulated values indicate that the reduction of radar cross section is more than 10 dB at 6−16 GHz. Our work reveals the availability of manipulating the waves, beamforming in communication systems and electromagnetic stealth, and so on.     

显化反应条件视角 发展反应调控意识——受控的燃烧

以波义耳研究燃烧的史实为背景,创新设计燃烧条件的探究实验,并提出“条件叠加式”燃烧条件探究新思路。以“燃灭控”为主线,一以贯之地显性化“条件是认识化学反应的一种基本视角”,落实“在一定条件下通过化学反应可以实现物质转化”的化学观念。基于调控化学反应思想创新设计“燃旺弱灭”反应控制视域,统整开展“情境”“活动”与“任务”三位一体的学习活动。重置教材实验的教学价值取向,结合燃烧的形式美、汉语言文字解读,将化学学科知识与美育、汉语言文化领域跨领域融合。     

二维纳米材料的改性及其环境污染物治理方面的应用

二维纳米材料是一类具有类似二维平面形态,且厚度在纳米级甚至数个原子层的材料,其种类繁多并且具有很多与体相材料不同的物化性质,在众多领域受到了广泛关注。二维纳米材料在催化降解、吸脱附、过滤、传感检测等领域具有可观的应用潜力,还可用于环境污染的防治。通过形貌、元素、基团、缺陷的修饰、改性和材料合成等策略可以调控二维纳米材料的性质,从而研发新的材料体系或者改善二维纳米材料的性能。本文首先归纳了二维纳米材料的种类,并重点阐述了各种改性策略的作用及研究现状,以及改性的二维纳米材料在治理水体污染、大气污染和污染物检测等方面的应用,为二维纳米材料在环境治理领域的发展现状作了系统介绍和展望。     

Pesticidal potential of some wild plant essential oils against grain pests Tribolium castaneum (Herbst, 1797) and Aspergillus flavus (Link, 1809)

The red flour beetle, Tribolium castaneum, and the mold Aspergillus flavus are well known threats of stored grain commodities, causing nutritional loss and poisoning of stored products, respectively. T. castaneum has developed resistance against most insecticides, leading to the use of extensive amounts of synthetic insecticides to protect stored grains. Synthetic pesticides not only toxify the environment but also cause serious health issues in humans using pesticide treated grains. This study aimed to identify plant-based natural pesticides to control T. castaneum and A. flavus. Essential oils were extracted from fresh aerial parts of Chenopodium ambrosioides, Conyza sumatrensis, Erigeron canadensis, and Tagetes minuta through steam distillation and investigated for insecticidal and anti-fungal activities against adult T. castaneum and A. flavus, respectively. GC–MS analysis of C. sumatrensis revealed the presence of 37.7% cis-lachnophyllum ester, 13.4% germacrene D, and 21.6% limonene, whereas in E. canadensis the major compounds were limonene, germacrene D, and cis-lachnophyllum ester (43.4%, 12.9% and 5.9%, respectively). In bioassays with treated grain, C. sumatrensis and E. canadensis essential oils exhibited excellent toxicity against adult T. castaneum with LD₅₀ of 3.7 and 5.6 mg per 10 g grains whereas in a fumigation bioassay they showed LD₅₀ of 6.6 and 10.6 mg/L, respectively. The essential oils extracted from C. ambrosioides and E. canadensis exhibited good anti-fungal activity against A. flavus. Our findings suggest that essential oils of C. sumatrensis and E. canadensis can play an important role in protecting stored grains from T. castaneum and A. flavus contamination.     

Fabrication and characteristics of self‐aggregation nanoparticles used for conformance control treatment

In order to alleviate the contradiction between injectability of the profile control agent and its profile control performance, a novel core‐shell heterogeneous structure colloidal particles (CSA) were synthesized, and the mechanism of self‐aggregation plugging was proposed. Cross‐linking inside the nanoparticles and chain‐growth polymerization via capturing acrylamide in the aqueous phase result in the formation of core‐shell heterogeneous structures as proved by TEM observation and XPS analysis. Moreover, CSA nanoparticles exhibit good hydrophilic properties, outstanding thermal stability and limited expansion capacity. Effects of different metal cations and surface group on the self‐aggregation time of CSA nanoparticles were systematically studied. Results showed that divalent cations contributed to more significant aggregation of CSA nanoparticles in comparison to monovalent cations. The increasing cations concentration and valency decreased the thickness of electric double layer, which lead to a decrease in the zeta potential. Core flooding test shows that the injection of nanoparticles which diameter is much smaller that of pore‐throats into the target reservoir can not only successfully enter the depth of porous media, but also effectively block the high permeability areas by the formation of self‐aggregation particle clusters. This study provides a new method for the equilibrium between nanoparticles injectivity and in‐depth profile control of nanoparticles.     

Coacervates as models of membraneless organelles

Coacervates are condensed liquid-like droplets, usually formed with oppositely charged polymeric molecules. They have been studied extensively in colloid and interface science for their remarkable material properties. The liquid–liquid phase separation underlying coacervate formation also plays an important role in the formation of various membraneless organelles (MLOs) that are found in many living cells. Therefore, there is an increasing interest to use well-characterized coacervates as in vitro models that mimic specific aspects of MLOs. Here, we review five aspects – physical and chemical properties, hierarchical organization, uptake selectivity, formation dynamics, and maturation – that are of particular interest and discuss how useful coacervates are to better understand these aspects of MLOs.     

丹荷颗粒治疗高脂血症质量标志物发现研究

为寻找丹荷颗粒治疗高脂血症的质量标志物,该研究基于丹荷颗粒体内成分分析结果,采用Cytoscape软件构建高脂血症-共有靶点-丹荷颗粒体内成分作用网络,利用DAVID及String数据库分别对共有靶点进行生物过程、通路富集及网络拓扑分析,明确丹荷颗粒降脂作用关键靶点及成分,再建立油酸诱导的HepG2细胞脂质堆积模型验证关键成分的降脂药效,最后结合相关成分在制剂中的含量、稳定性、特征性综合确定质量标志物。结果发现,丹荷颗粒体内成分作用于CES1、ADORA2A、ADORA1、APOB、LDLR、PPARA、PPARG、INSR、ESR2、ESR1共10个高脂血症疾病靶点,主要参与脂质代谢过程以及PPAR、cAMP信号通路,其中LDLR、PPARA、PPARG可能是关键靶点,而网络中与关键靶点直接作用的成分为白藜芦醇、柚皮素。白藜芦醇和柚皮素均可降低油酸诱导的HepG2细胞内脂滴数量,改善细胞脂质堆积严重程度,并显著降低细胞内甘油三酯含量,可能为关键成分;鉴于入体成分白藜芦醇和柚皮素来源于制剂中虎杖苷及柚皮苷,且制剂中虎杖苷及柚皮苷特征明显、含量丰富、稳定,故虎杖苷及柚皮苷可作为丹荷颗粒治疗高脂血症的质量标志物。该研究为丹荷颗粒质量标准的建立提供了合理的候选质控指标。