g-C3N4 Nanosheet Supported CuO Nanocomposites for the Electrochemical Carbon Dioxide Reduction Reaction.

We have prepared CuO-derived electrocatalysts on a graphitic carbon nitride (g-C3N4) nanosheet support for the electrochemical carbon dioxide reduction reaction (CO2RR). Highly monodisperse CuO nanocrystals made by a modified colloidal synthesis method serve as the precatalysts. We use a two-stage thermal treatment to address the active site blockage issues caused by the residual C18 capping agents. The results show that the thermal treatment effectively removed the capping agents and increased the electrochemical surface area. During the process, the residual oleylamine molecules incompletely reduced CuO to a Cu2O/Cu mixed phase in the first stage of thermal treatment, and the following treatment in forming gas at 200 °C completed the reduction to metallic Cu. The CuO-derived electrocatalysts show different selectivities over CH4 and C2H4, and this might be due to the synergistic effects of Cu-g-C3N4 catalyst-support interaction, varied particle sizes, dominant surface facets, and catalyst ensemble. The two-stage thermal treatment enables sufficient capping agent removal, catalyst phase control, and CO2RR product selection, and with precise controls of the experimental parameters, we believe that this will help to design and fabricate g-C3N4-supported catalyst systems with narrower product distribution.

Anthropometry of external auditory canal by non-contactable measurement.

Human ear canals cannot be measured directly with existing general measurement tools. Furthermore, general non-contact optical methods can only conduct simple peripheral measurements of the auricle and cannot obtain the internal ear canal shape-related measurement data. Therefore, this study uses the computed tomography (CT) technology to measure the geometric shape of the ear canal and the shape of the ear canal using a non-invasive method, and to complete the anthropometry of external auditory canal. The results of the study show that the average height and width of ear canal openings, and the average depth of the first bend for men are generally longer, wider and deeper than those for women. In addition, the difference between the height and width of the ear canal opening is about 40% (p < 0.05). Hence, the circular cross-section shape of the earplugs should be replaced with an elliptical cross-section shape during manufacturing for better fitting.