Ca-Mn co-doping LaCrO3 coating with high emissivity and good mechanical property for enhancing high-temperature radiant heat dissipation

Two techniques, including spray drying and electrostatic spray, were applied to produce feedstocks for preparing Ca-Mn co-doping LaCrO₃ ceramic coatings with two different structures on Ni-based alloy by the atmospheric plasma spraying method. The results show that coating from feedstocks produced by spray drying exhibits lower roughness and porosity than the coating from feedstocks produced by electrostatic spray due to the full melting of smaller feedstocks. Higher proportion of melting zones is beneficial to enhance the ratio of hardness to modulus to improve wear resistance. The emissivity of the coatings with roughness from 0.65 µm to 4.6 µm is all above 0.9 in the waveband of 1–14 µm at room temperature. What’s more, structure-dependent emissivity is affected by surface roughness and pore size due to the infrared scattering. The temperature-dependent thermal infrared emissivity at 1–14 µm decreases with the increasing temperature, and is still above 0.67 at 1200 °C.     

水溶性固体壳聚糖盐的制备及其性能研究

通过半湿研磨法由壳聚糖制备了多种水溶性粉末状壳聚糖盐。该产品可以溶解在酸性、中性和弱碱性介质中,溶解范围扩大;水溶液pH值在3.36—5.54之间,而且具有较强的缓冲作用;吸湿率提高30%以上。通过红外光谱、X-射线衍射、质量损失曲线及电位滴定曲线对目标产物结构进行分析,结果表明,在无溶剂条件下实现了壳聚糖氨基的质子化反应而不是简单的物理吸附,因此产品性能稳定。该方法操作简单,无污染而且经济。     

单凝聚法制备壳聚糖硬脂酸钠为壁材的鱼油微胶囊

为探究疏水性壳聚糖衍生物的应用,丰富微胶囊壁材的选择,选取壳聚糖硬脂酸钠为壁材,鱼油为芯材,采用单凝聚法制备鱼油微胶囊,通过单因素实验和正交实验对制备条件进行了优化,同时采用红外光谱、X-射线衍射光谱、扫描电镜和热重分析仪对鱼油微胶囊的结构、形貌和热稳定性进行了表征。结果表明：适宜的鱼油微胶囊制备条件为壁芯质量比1∶ 1、乳化剂吐温-20质量浓度14.40 g/L（芯材质量1 g时,加入乳化剂溶液200 mL）、超声功率720 W,此条件下鱼油包埋率为（50.00±0.47）%;所制备的鱼油微胶囊粒径分布均匀,热稳定性较好,存放18个月后,热稳定性几乎无变化。疏水性壳聚糖硬脂酸钠壁材制备简便,通过单凝聚法成囊后,能有效保持微胶囊热稳定性。     

A flexible nanostructured paper of MnO NPs@MWCNTs/r-GO multilayer sandwich composite for high-performance lithium-ion batteries

Designing a high capacity and long cycle life MnO-based composite material for lithium ion batteries (LIBs) is still a great challenge because of the intrinsically low electrical conductivity and dramatic volume variations during lithiation/delithiation. In this paper, the MnO nanoparticles (MnO NPs) are recombined with multi-walled carbon nanotubes (MWCNTs) and reduced graphene oxide (r-GO) to rationally construct a novel MnO NPs@MWCNTs/r-GO multilayer sandwich structure via electrostatic interaction self-assembly and vacuum filtration processes. As a result, the MnO NPs are closely attracted in the conductive MWCNTs network, and the MWCNTs adsorbed on the surface of MnO NPs can be served as a soft and flexible carbon coating layer to self-adapt the huge volume expansion. For another, the r-GO between two MnO NPs@MWCNTs layers is the cause to form a free-standing paper, enhancing the transverse conductivity of the whole electrode simultaneously. These features will contribute to achieve excellent cycling stability and improved rate capability.     

天然花青素的抗氧化机制及功能活性研究进展

花青素是一类广泛存在于被子植物中的天然水溶性色素,因特殊的化学结构而具有较强的抗氧化活性,在食品、药品、护肤品等领域广泛应用。花青素的抗氧化性是其生理活性的基础,本文综述了花青素可能的抗氧化机制,包括减少活性氧积累和清除自由基、激活酶抗氧化系统、减少DNA损伤、与金属离子发生作用;从抗肿瘤作用、抑菌作用、对脂类、糖类代谢的调节作用、抗疲劳和抗衰老作用、调节肠道菌群和保护视力六方面介绍了花青素的功能活性,以期为进一步拓宽花青素的应用领域提供理论参考。     

Synthesis of titanoaluminosilicates isomorphous to zeolite Beta,active as oxidation catalysts

Isomorphous replacement of Si by Ti in the low aluminum-containing zeolite Beta framework has been achieved by direct synthesis. The crystallization must be carried out in the absence of alkali cations, as they promote the precipitation of amorphous titanosilicate. The incorporation of Ti to the framework has been characterized by XRD, i.r., and thermal analysis. Ti is believed to perform a stabilizing role of the Beta framework similar to that of Al. The large pores of [Al, Ti]-Beta compared to TS-1 allow the use of this material as a catalyst in the selective oxidation of cyclododecane with hydrogen peroxide.