Journal of Mechanical Science and Technology - The super-twisting algorithm (STA, a class of second-order sliding mode control (SOSMC)) is widely used in permanent magnet linear synchronous motor... 相似文献
Scientometrics - Short communications are an integral part of academic journal publishing since they serve as a forum for scholarly debate on recently published journal articles. Their prestige and... 相似文献
Electrocatalytic water splitting for hydrogen production plays a vital role in the development of new energy field, but there is still a lack of low-content precious metal or cost-effective non-noble metal catalysts for the hydrogen evolution reaction (HER). Therefore, how to develop the catalysts with a smaller amount of precious metal to achieve higher performance is still a major challenge. Herein, we have fabricated Ru–Ni2P@Ni(OH)2/NF-2 heterostructure by phosphating Ni(OH)2/NF and then anchoring Ru on the surface through wet chemical strategy. Benefiting from its optimal ΔGH1 and synergistic effect, this Ru–Ni2P@Ni(OH)2/NF-2 catalyst shows superior electrocatalytic HER kinetics in alkaline electrolyte. A small overpotential of 31 mV is needed for this electrocatalyst to obtain the current densities of 10 mA cm?2 with remarkable durability over 24 h. This work provides a new strategy for the preparation of effective HER electrocatalyst with a low precious metal content. 相似文献
The present study aims to examine fruit cell wall-associated fruit softening in Lycium barbarum L. by the microstructure of the fruit cells and the changes in the contents of cell wall components, molecular weights of cell wall polysaccharides and the activities of related cell wall degrading enzymes at different development stages of L. barbarum L. fruit. Fruit firmness significantly declined during ripening, with the greatest reduction between the 28 and 35 days stages. The decrease in firmness correlated with an extensively deformed microstructure in the parenchyma tissues and positively correlated with reductions in the contents of fruit cell wall materials and molecular weight in cell wall polysaccharide. Cellulase, α-galactosidase, polygalactosidase and pectin methylesterase showed higher activities during 28 days; whereas, the activities of β-galactosidase were higher during 35 days. These results indicate that cell wall-related processes are a key feature of early softening in L. barbarum L. 相似文献
Liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) was employed to investigate free phenols that were released from purple sweet potato (PSP) by alkaline, acid and enzymatic hydrolysis. Four phenolic acids, including ferulic, isoferulic, 4-hydroxybenzoic and caffeic acids, were identified. Based on their effects on the characteristics of purple sweet potato starch (PSPS), the four phenolic acids were studied. Furthermore, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT–IR) and X-ray diffraction (XRD) techniques were employed to explore the microstructures of the complexes of the phenolic acids and PSPS. The obtained results demonstrated that the pasting, thermal, retrogradation, as well as digestive properties of PSPS were all influenced by the phenolic acids which interacted with PSPS through noncovalent hydrogen bonds. The influence of the four phenolic acids on the properties of PSPS was in the descending order: 4-hydroxybenzoic acid > ferulic acid > caffeic acid > isoferulic acid. 相似文献
The easy loss of crosslinking ions in alginate can result in a structural collapse of the physiological environment, thereby losing its characteristics as a bone scaffold. Meanwhile, alginate lacks osteoconductive properties, which are necessary for ideal bone scaffolds. In this study, strontium (Sr) in combination with calcium (Ca) at different ratios were used as a crosslinking agent for the alginate to investigate the effect of Ca–Sr ratio on the physicochemical properties and biological preformation of alginate hydrogel. Here, Ca and Sr in different weight ratios (4:0, 3:1, 2:2, 1:3, and 0:4) were employed as crosslinking agents. The physicochemical properties of hydrogels, including pore size, elastic modulus, degradation rate and swelling ratio, could be effectively tuned by controlling the amount of Sr. The ion release experiment revealed a burst release of Sr2+ in the first day after crosslinking. However, after 3 days, the amount of Sr2+ release had significantly declined and was proportional to the total strontium initially introduced into the alginate. Meanwhile, the live/dead results exhibited higher cell viability for alginate with 2:2 Ca–Sr weight ratio. The alginate with 2:2 Ca–Sr ratio not only improved osteoblastic attachment, but also up-regulated the alkaline phosphatase activity, the expression of osteogenic marker genes, and relative growth factors. These findings indicate that alginate with 2:2 Ca–Sr ratio might be a promising scaffold for bone tissue engineering.