Ag nanoparticles encapsulated by TiO2 shells have the ability to catalyze redox reactions on their surface. By continually monitoring by use of UV–visible spectroscopy
it was found that the surface charge of both TiO2-coated and uncoated colloidal silver particles changed after chemical electron injection. The charging and discharging process
of Ag@TiO2 vary, depending on the different Ag content of the core–shell nanoparticles. In order to enhance the stability of Ag@TiO2 colloids, Fe3+ was doped into the lattice of the TiO2 shells. The experimental results showed that the Fe3+ ions have the capacity to store and transfer electrons. Furthermore, the charging and discharging rate can be controlled
by changing the thickness of the TiO2 shells, because they are limited by the diffusion distance of electrons through the TiO2 shells. 相似文献
Effects of temperature on self‐interaction of human‐like collagen (HLC) were investigated by hydrophobic interaction chromatography, calorimetric measurement, and sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE) analysis. Results show that three types of interaction roles may exist between HLC molecules at 3–50°C, which were divided into three narrower temperature ranges. In temperature range from 3–22°C, hydrogen bonding plays a key role in the formation of a gelatinous aggregate. In the range of 22–38°C, hydrophobic bonds accompanied by hydrogen bonds are involved in the formation compact aggregates. When temperature is above 38°C the hydrophobic effect formed in the HLC monomer results in the loss of its ability to self‐interact. 相似文献
Sodium‐ion batteries (NIBs) are the most promising alternatives to lithium‐ion batteries in the development of renewable energy sources. The advancement of NIBs depends on the exploration of new electrode materials and fundamental understanding of working mechanisms. Herein, via experimental and simulation methods, we develop a mixed polyanionic compound, Na2Fe(C2O4)SO4?H2O, as a cathode for NIBs. Thanks to its rigid three dimensional framework and the combined inductive effects from oxalate and sulfate, it delivered reversible Na insertion/desertion at average discharging voltages of 3.5 and 3.1 V for 500 cycles with Coulombic efficiencies of ca. 99 %. In situ synchrotron X‐ray measurements and DFT calculations demonstrate the Fe2+/Fe3+ redox reactions contribute to electron compensation during Na+ desertion/insertion. The study suggests mixed polyanionic frameworks may provide promising materials for Na ion storage with the merits of low cost and environmental friendliness. 相似文献
Aiming at the problem that the damping coefficient of the traditional hydro-pneumatic spring cannot be adjusted in real-time, the magnetorheological (MR) damping technology was introduced into the traditional hydro-pneumatic spring with single gas chamber. A new shear-valve mode MR hydro-pneumatic spring was proposed. And its dynamic performance was analyzed based on multi-physical coupling simulation and mechanical property test. Firstly, a structural scheme of MR hydro-pneumatic suspension was proposed to ensure the original height adjustment function based on the working principle of traditional hydro-pneumatic suspension with single gas chamber. Secondly, based on the design requirements, the parameter of MR hydro-pneumatic spring damping structure was designed by using MR damper design method. Thirdly, the multi-physical coupling dynamic performance of the MR hydro-pneumatic spring damping structure was analyzed based on the electromagnetic field analysis theory, flow field analysis theory and thermal field analysis theory. The analysis results showed that the designed MR hydro-pneumatic spring has reasonable magnetic circuit structure and excellent working performance. Then, the mechanical properties of MR hydro-pneumatic spring were tested. The results showed that the maximum damping force can reach 20 kN, and the dynamic adjustable multiple can reach 6.4 times. It has good controllability and meets the design requirements. Finally, a nonlinear model of MR hydro-pneumatic spring was established based on the elastic force calculation model of the gas and the Bouc–Wen model. The simulation results of the established model agree well with the experimental results, which can accurately describe the dynamic properties of the hydro-pneumatic spring. The proposed design and modeling method of the MR hydro-pneumatic spring can provide a theoretical basis for the related vibration damping devices.
An isometric immersion ${x:M^n\rightarrow S^{n+p}}$ is called Willmore if it is an extremal submanifold of the Willmore functional: ${W(x)=\int\nolimits_{M^n} (S-nH^2)^{\frac{n}{2}}dv}$, where S is the norm square of the second fundamental form and H is the mean curvature. Examples of Willmore submanifolds in the unit sphere are scarce in the literature. This article gives a series of new examples of Willmore submanifolds in the unit sphere via isoparametric functions of FKM-type. 相似文献
For a closed hypersurface Mn ⊂ Sn+1(1) with constant mean curvature and constant non-negative scalar curvature, we show that if \({\rm{tr}}\left({{{\cal A}^k}} \right)\) are constants for k = 3, …, n − 1 and the shape operator \({\cal A}\) then M is isoparametric. The result generalizes the theorem of de Almeida and Brito (1990) for n = 3 to any dimension n, strongly supporting the Chern conjecture.