Hydrocalumite structured layered double hydroxides (LDHs) with various Fe³⁺ ratios were prepared through a coprecipitation method. In order to control the Fe³⁺ content in LDH, binary Ca–Fe LDHs were first synthesized with various Ca/Fe ratios. The X-ray diffraction pattern showed that only a limited Ca/Fe ratio resulted in LDH formation. The Fe³⁺ content in LDH was controlled by applying Al³⁺ while the divalent and trivalent metal ratio was set to 2. Through X-ray diffraction patterns, ternary LDHs with Ca–Al–Fe composition were successfully synthesized without significant impurities, with the Al increasing crystallinity. Quantification showed that Al moiety participated in the formation of the LDH framework more than Ca and Fe, implying a structural stabilization in the presence of Al. In order to investigate the global and local structure of Fe moiety in the LDH, both solid state UV-vis and X-ray absorption spectroscopies were carried out. Both spectroscopies revealed that the existence of Al induced slight local distortion in coordination but global crystal stabilization.

The emulsifying ability of the naturally occurring surfactant deoxycholic acid (DCA) was improved by dynamic interaction with nanometric layered particles, layered double hydroxide (LDH). As DCA molecules are rigid due to the facial configuration of hydrophobic–hydrophilic groups, they tend to form molecular aggregation in an acidic condition or imbalanced water–lipid ratios. In this study, the homogeneous hybrids of DCA and LDH were obtained by the in situ growth of LDH at a DCA molecule. The DCA−LDH hybrid successfully prevented the molecular aggregation of DCA at an acidic pH and imbalanced water–to–oil ratio. The dynamic light scattering showed that the hydrodynamic radius of micelle in the emulsion made with DCA−LDH maintained its small size (<500 nm), while upon pH change and dilution with water, that made with DCA only uncontrollably increased up to ~3000 nm. The polydispersity index value of the DCA–LDH emulsion remained constant (<0.3) after the pH change and dilution with water, indicating the high stability of the formulation. Furthermore, time-dependent turbidity monitoring revealed that the DCA-only formulation suffered from serious coalescence and creaming compared with the DCA–LDH formulation. It is suggested that the dynamic interaction between LDH layers and DCA prevented molecular aggregation under unfavorable conditions for the oil–in–water emulsion.

Different methods have different applicability and a single test is not a full, objective, realistic way to reflect the operating state of the switchgear. Transient Earth Voltage detection has been widely promoted in the regular testing of the switchgear by virtue of the advantages of non-power failure detection, high sensitivity, strong anti-interference ability and non-invasion, etc. However, the research on the detection mechanism, influencing factors and propagation characteristics of TEV method is still in its initial stage. On the basis of theoretical analysis of partial discharge transmission characteristics and influencing factors, established the finite element model of the switch cabinet and deduced the TEV transmission characteristics and relationship between partial discharge source and its influenced factors. The conclusion was confirmed by using the online measured TEV data.