The Mpemba effect is one of the most perplexing puzzles in nature. Although it has been discussed extensively, direct observation of the Mpemba effect is extremely challenging and rare. Herein, we report the first systematic study of the Mpemba effect with water and clearly point out the conditions required for the observation of the Mpemba effect. The results demonstrate that hot water usually has a faster cooling rate than cold water. The initial temperature, temperature difference, shape of the container, and water volume influence the heat exchange and the cooling process. Owing to the influential factors of heat exchange, the Mpemba effect can only be observed under specific conditions. This work helps to clarify doubts and confusion about the Mpemba effect and can offer alternative strategies for energy storage and transfer materials.

In the field of flexible electronics manufacturing, inkjet printing technology is a research hotspot, and it is key to developing low-temperature curing conductive inks that meet printing requirements and have suitable functions. Herein, methylphenylamino silicon oil (N75) and epoxy-modified silicon oil (SE35) were successfully synthesized through functional silicon monomers, and they were used to prepare silicone resin 1030H with nano SiO2. 1030H silicone resin was used as the resin binder for silver conductive ink. The silver conductive ink we prepared with 1030H has good dispersion performance with a particle size of 50–100 nm, as well as good storage stability and excellent adhesion. Additionally, the printing performance and conductivity of the silver conductive ink prepared with n,n-dimethylformamide (DMF): proprylene glycol monomethyl ether (PM) (1:1) as solvent are better than those of the silver conductive ink prepared by DMF and PM solvent. Cured at a low temperature of 160 °C, the resistivity of 1030H-Ag-82%-3 conductive ink is 6.87 × 10−6 Ω·m, and that of 1030H-Ag-92%-3 conductive ink is 0.564 × 10−6 Ω·m, so the low-temperature curing silver conductive ink has high conductivity. The low-temperature curing silver conductive ink we prepared meets the printing requirements and has potential for practical applications.