Extraction of Lepidium apetalum seed oil using supercritical carbon dioxide and anti-oxidant activity of the extracted oil

The supercritical fluid extraction (SFE) of Lepidium apetalum seed oil and its anti-oxidant activity were studied. The SFE process was optimized using response surface methodology (RSM) with a central composite design (CCD). Independent variables, namely operating pressure, temperature, time and flow rate were evaluated. The maximum extraction of Lepidium apetalum seed oil by SFE-CO? (about 36.3%) was obtained when SFE-CO? extraction was carried out under the optimal conditions of 30.0 MPa of pressure, 70 °C of temperature, 120 min of extraction time and 25.95 L/h of flow rate. GC-MS analysis showed the presence of four fatty acids in Lepidium apetalum seed oil, with a high content (91.0%) of unsaturated fatty acid. The anti-oxidant activity of the oil was assessed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay and 2,2'-azino- bis(3-ethylbenzthiazoline-6-sulphonic acid) diammonium salt (ABTS) test. Lepidium apetalum seed oil possessed a notable concentration-dependent antioxidant activity, with IC?? values of 1.00 and 3.75 mg/mL, respectively.     

Effect of Polyaniline (Emeraldine Base) Addition on α to β Phase Transformation in Electrospun PVDF Fibers

A facile and effective transformation of α to β phase in electrospinning of PVDF was demonstrated by adding emeraldine base polyaniline (PANI). Results from FTIR and X-ray studies revealed that a very large amount of the electraoctive β-phase can be obtained by controlling the amount of PANI loading and the electrospinning parameters, whereas the γ-phase normally showed a very tiny amount, much lower than the β-phase, for all samples with PANI loading. The above results indicate that the addition of PANI into the PVDF solution during electrospinning is a powerful way to enhance the electroactive β-phase of the fibers, which is significant for developing high-performance fiber-based piezoelectric devices.     

Contact electrification property controlled by amino modification of cellulose fibers

Cellulose - As a green material, cellulose is widely used in friction triboelectric nanogenerators (TENGs). However, the weak polarity of the cellulose fibers surface leads to its weak contact...     

近红外波段硅基金属光子晶体平板的亚波长成像特性

利用时域有限差分方法,理论上研究了由正方形金属嵌入背景材料硅中组成的二维正方晶格和三角晶格光子晶体的亚波长成像特性。采用Drude模型描述金属银的色散特性,在近红外波段该模型可以很好地描述金属的实际介电常数。通过结构参数的设计,在上述两种结构中实现了波长在1550nm附近的亚波长成像,并且发现金属对入射光的吸收使得成像位置处的光强稍有降低,但是对于光子晶体亚波长成像的质量并无影响。相对于通常的硅基空气孔型光子晶体亚波长成像器件,该种硅基金属型全固态光子晶体结构更加稳定,因而可以更好地在复杂全光集成回路中加以实际应用。     

二维八重准晶有机光子晶体平板的光学传播特性

采用时域有限差分法研究了二维八重准晶有机光子晶体的光传输特性,重点分析了光束在聚苯乙烯空气柱平板结构和聚苯乙烯介质柱结构中的透射特性与光局域特性。研究结果表明,即使在低折射率对比度的情况下,两种完整八重准晶平板结构中均出现了可见光波段的光子带隙和本征模,且光子带隙中心位置随着平板厚度的增大而红移。当在两种准晶结构中引入缺陷微腔时,带隙内的缺陷模产生位置和波长红移特性随着微腔结构的变化规律明显不同,这种差异性是由两种物理机制(即光子晶体缺陷能级变化与微腔所支持的驻波条件)共同作用的结果。这一研究结果将为实验制备有机准晶发光器件提供一定的理论基础。     

Low-cost,environmentally friendly and high-performance cellulose-based triboelectric nanogenerator for self-powered human motion monitoring

Cellulose-based triboelectric nanogenerators (TENGs) can provide power for various monitoring devices and are environmentally friendly and sustainable. Chemical functional modification is a common method to improve the electrical output performance of cellulose-based TENGs. In this work, an environmentally friendly high-performance triboelectric nanogenerator based on a polydopamine/cellulose nanofibril (PDA/CNF) composite membrane and fluorinated ethylene propylene was developed. Dopamine generates polydopamine nanoparticles through oxidative self-polymerization and adheres to the surface of nanofibers. The synergistic effect of amino group introduction and membrane surface microstructure effectively enhanced the output performance of TENGs to a certain extent. The effects of PDA content, CNF composite film thickness and different working conditions on the electrical output were systematically investigated. The optimized PDA/CNF-TENGs exhibited an enhanced electrical output performance with voltage, current, and power density values of ≈205 V, ≈20 µA, and ≈48.75 μW·cm^?2, respectively. The PDA/CNF-TENGs exhibited stable and identifiable signals when used as a self-powered sensor for human motion monitoring, showing the potential prospects of cellulose materials for TENGS and other electronic applications.

Graphical abstract

     

液体表面张力系数测量实验的改进

在原有实验的基础上,采用控制液面下降法,将原实验仪器中的表面皿换成测量杯,利用放水阀控制液体流出速度,从而使数字电压表的示数在液膜拉断前后容易观察,另外在测量杯上标出水平线,以便于判断吊环与液面平行,这样测量出的液体表面张力系数更接近实际值。