Ni/Co/Co3O4@C nanorods derived from a MOF@MOF hybrid for efficient overall water splitting.

The design of nanostructured materials for efficient bifunctional electrocatalysts has gained tremendous attention, yet developing a fast and effective synthesis strategy remains a challenge. Here, we present a fast and scalable synthetic method of Ni/Co/Co3O4@C nanorods for efficient overall water splitting. Using microwave synthesis, we first produced a unique Ni-MOF@Co-MOF in a few minutes. Subsequently, we transformed the MOF@MOF into hybrid Ni/Co/Co3O4 nanoparticles covered with graphitic carbon in a few seconds using laser-scribing. The prepared bimetallic catalysts showed remarkably low overpotentials of 246 mV for the oxygen evolution reaction (OER) and 143 mV for the hydrogen evolution reaction (HER) at a current density of 30 mA cm-2. An electrolyzer assembled with the bimetallic catalysts delivered a high current density of 20 mA cm-2 at a voltage of 1.6 V and exhibited good durability (nearly 91.6% retention even after a long-running operation of 24 h at a voltage of 1.52 V). Our proposed method could serve as a powerful method for creating various multimetallic hybrid nanocatalysts with unique hierarchical structures from diverse MOFs.

The dental arch dimensions in Vietnamese children at 7 years of age, and their variation by gender and ethnicity.

PURPOSE: Dental arch dimensions are important not only in dentistry (e.g. orthodontists and prosthodontists, and forensic odontology), but also other medical fields, biology, biometrics, painting or sculpture. This study aimed to determine these dimensions in Vietnamese children and compare these measurements across four ethnic groups and genders. METHODS: A cross-sectional study was conducted on 3204 Vietnamese children at 7 years of age from four major ethnic groups in Vietnam (Kinh, Tay, Thai and Muong). RESULTS: The means variables in study subjects were 33.72 ±â€¯2.16 mm for upper inter-canine width (UCW); 52.74 ±â€¯2.55 mm for upper inter-molar width (UMW); 8.69 ±â€¯1.79 mm for upper anterior length (UAL); 29.59 ±â€¯1.97 mm for upper posterior length (UPL); 26.94 ±â€¯2.49 mm for lower inter-canine width (LCW); 45.89 ±â€¯2.59 mm for lower inter-molar width (LMW); 5.04 ±â€¯1.53 mm for lower anterior length (LAL); and 26.22 ±â€¯2.07 mm for lower posterior length (LPL). The UCM, UMW, and LMW of Muong were significantly wider in males, but narrower in females compared with other ethnic groups. The Kinh, Tay and Thai groups had no significant differences between genders in all dimensions, but these sizes were significantly larger in males than females of Muong group. CONCLUSIONS: This study presents the means of dental arch dimensions in 7 year-old Vietnamese children, and there is no statistical differences in these dimensions between genders of almost studied groups, except Muong group. Ethnic differences are observed only in UCW, UMW and LMW of Muong vs other groups. Furthermore, Vietnamese children have dental arch width similar to the African and Caucasian.