Solvent terminated natural deep eutectic solvent microextraction for concentration of curcuminoids in Curcumae Longae Rhizoma and turmeric tea

A novel solvent terminated microextraction method based on a natural deep eutectic solvent (L-menthol and lactic acid at a molar ratio of 1:2) coupled with high-performance liquid chromatography was proposed, which was utilized for the separation and enrichment of bisdemethoxycurcumin, demethoxycurcumin and curcumin in Curcumae Longae Rhizoma and turmeric tea. The effects of independent parameters on extraction efficiency were optimized by single-factor analysis. Subsequently, four predominated parameters affecting the extraction procedure, including extractant volume, salt concentration, demulsifier consumption, and demulsification time, were further evaluated by a central composite design. Under the optimized conditions, the linear ranges of calibration curves were 0.005–0.5 μg/mL for bisdemethoxycurcumin, 0.004–0.4 μg/mL for demethoxycurcumin, and 0.0045–0.45 μg/mL for curcumin, respectively. In addition, the developed method provided low detection limits (0.1–0.4 ng/mL) and high enrichment factors (279–350). Its intra-day and inter-day precision were carried out by relative standard deviation ranging from 2.2 to 9.2%. Finally, the applicability of this method was assessed by the analysis of Curcumae Longae Rhizoma and turmeric tea samples. The results showed that these samples were detected successfully and the spiked recoveries over the range of 85.3-108.9% with relative standard deviations of 1.6-8.9% were attained, indicating its high relative recoveries with good precision in real sample analysis.     

UHPLC-DAD Characterization of Origanum vulgare L. from Atacama Desert Andean Region and Antioxidant,Antibacterial and Enzyme Inhibition Activities

The Lamiaceae family is an important source of species among medicinal plants highly valued for their biological properties and numerous uses in folk medicine. Origanum is one of the main genera that belong to this family. The purpose of the study was to determine the phenolic composition of the Origanum vulgare extract and evaluate the antimicrobial, antioxidant, and inhibitory activities of this species that grows in the Andean region of the Atacama Desert. High-performance liquid chromatography was performed to determine the main phenols. Rosmarinic acid was identified as the predominant phenolic compound in this species (76.01 mg/100 g DW), followed by protocatechuic acid, which to our knowledge, no previous study reported similar concentrations in O. vulgare. The oregano extract exhibited a content of total phenolic (3948 mg GAE/100 g DW) and total flavonoid (593 mg QE/100 g DW) with a higher DPPH antioxidant activity (IC₅₀ = 40.58 µg/mL), compared to the same species grown under other conditions. Furthermore, it was found to inhibit α-glucosidase activity with an IC₅₀ value (7.11 mg/mL) lower than acarbose (129.32 mg/mL). Pseudomonas syringae and Pantoea agglomerans (both MIC 0.313 mg/mL and MBC 1.25 mg/mL) were the bacteria most susceptible to oregano extract with the lowest concentration necessary to inhibit bacterial growth. These results open the door for the potential use of this plant to manage chronic diseases, and they expand the knowledge of the species cultivated in arid environmental conditions.     

NMR波谱仪集中优化管理模式

论述了核磁中心采用的相对集中管理模式.集中管理模式主要体现在上样辅助、中央供气、数据集中上传与下载3个方面.另外,还提出了未来可以从集中供高纯N2和LN22个方面进一步改善中心的集中管理模式,从而能够更好的优化测试效率和工作环境.     

A novel model for quantification of the moisture absorption of polymeric laminated composites

In the present study, a new model was developed that considers the amount of the environmental fluid absorption by different constituents of polymeric laminated composites including fibers, resin, fiber-matrix interphase region, ply interface region, and voids. By knowing the fluid absorption behavior of the composite constituents, the present model can predict the amount of fluid absorption of different constituents of polymeric laminated composites with an arbitrary resin volume fraction and stacking sequence. Test specimens were fabricated by glass fibers and vinyl ester resin. The environmental fluids, examined in this study, were distilled and saline water under different temperatures and salt concentrations. To investigate the absorption behavior of different constituents of polymeric composite, various tests were conducted on fibers, pure cured resin, unidirectional composite specimens, and laminated composites. Based on the results of the tests, a new theoretical model was developed to quantify and predict the amount of fluid absorption of different constituents of laminated polymeric composites. The thickness of the interphase region between the fiber and matrix was also measured using the scanning electron microscope (SEM) images and nano-indentation tests. The consistency of experimental results with the outcomes of the theoretical model indicates the accuracy of the model.     

含中心裂纹梯度纳晶金属的数值模拟

梯度纳晶金属由于其微观组织的梯度分布,力学属性也呈现梯度变化,这使得其表现出不同于传统均匀材料的断裂行为．利用材料力学参数的梯度分布来表征梯度纳晶金属中晶粒尺寸的梯度变化,并编写ABAQUS和MATLAB脚本程序建立分层有限元模型．通过数值模拟计算了含有初始中心裂纹的梯度纳晶金属在受远端均匀拉应力作用下的裂尖J积分,分别研究了屈服应力梯度、裂纹角度和裂纹长度对金属材料断裂韧性的影响,并与传统粗晶进行了对比．结果表明梯度纳米结构的存在导致梯度纳晶金属内部的中心裂纹两端表现出不同的断裂韧性,小晶粒一侧裂尖的抗裂韧性优于大晶粒一侧裂尖,且屈服应力梯度绝对值越大,两者差距越大．梯度纳晶金属的断裂韧性受中心裂纹角度和长度变化的影响与传统粗晶金属基本一致,同时在晶粒尺寸梯度的作用下梯度纳晶的裂尖J积分略低于粗晶,即整体上拥有更好的抗裂韧性．     

相伴随机变量序列的泛函型几乎处处中心极限定理

对于均值为零的平稳相伴随机变量序列,首先证明了在L(n)=EX_1~2 2 sum from n to j=2 Cov(X_1,X_j)是一个缓变函数的条件下的泛函型几乎处处中心极限定理.另外还给出了正则化部分和函数的对数平均几乎处处收敛性.     

浑水中非均匀光场探测图像方法

分析了传统的水下观测和激光观测技术在能见度约为0.5~1.5 m的浑浊水域和0.2 m的特浑水域观测遇到的理论和技术上的局限性.叙述了一种非均匀光场集束光水下目标图像探测方法和系统,并在各种浑浊水质中进行其特性的试验.试验结果表明该系统基本上解决了浑浊水中的观测问题.     

中红外波段二阶非线性光学晶体材料研究进展

新型无机红外波段二阶非线性光学晶体材料在光电子领域有着重要的应用，对它们的探索是当前非线性光学材料研究领域的难点和前沿方向之一。本文将材料按组成分成三大类（即经典的ABC₂型黄铜矿结构化合物，硫属元素其他化合物和AMX₃型卤化物），分别就新材料探索、已知材料的单晶生长等综述了近10余年来中红外波段二阶非线性光学晶体材料的研究进展。     

Secondary succession and its effects on soil moisture and nutrition in abandoned old-fields of hilly region of Loess Plateau, China

Floristic composition, community structure and soil moisture and nutrient contents in abandoned fields of different ages were analyzed to clarify the regenerative aspects of succession as a tool for vegetation restoration. The results indicated that secondary succession in this region can be interpreted as an auto-succession: there are main changes in species-relative abundance and species turnover. Annual or biennial species (e.g. Artemisia scoparia), acted as pioneers and strongly dominated the early stages. Then, they underwent a progressive decline, while forbs (e.g. Artemisia sacrorum) and grasses (e.g. Xanthium sibiricum) had their peak abundance at intermediate stages. Dwarf shrubs (e.g. Lespedeza dahurica) and short rhizome grass (e.g. Bothriochloa ischaemum) appeared at mid-succession stage and gradually increased in abundance during succession, becoming dominant at late stages. The first axis of detrended correspondence canonical analysis arranged the sites according to their fallow time, indicating a successional sere. The second axis, associated with diverging pathways of regeneration, correlated with topographic factors and soil moisture and nutrition. Structural divergence between plots increased as succession went on, attained the highest at the mid-succession stage, decreased at the late stage.

Soil moisture and available phosphorus content decreased steadily with field age after their abandonment, whereas pools of organic matter, total and available nitrogen, potassium and total phosphorus increased with field age. The pace and direction of recovery of native vegetation and natural soil properties in these abandoned fields resembled classic old-field succession, which is a form of secondary succession that often serves as a template for guiding restoration efforts. Interface between the abandoned field soil and plant system was crucial to the above process. Our current study supported the generally accepted hypothesis in the succession literature.