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Despite its unrivaled hardness, diamond can be severely worn during the interaction with others, even softer materials. In this work, we calculate from first-principles the energy and forces necessary to induce the atomistic wear of diamond and compare them for different surface orientations and passivation by oxygen, hydrogen, and water fragments. The primary mechanism of wear is identified as the detachment of the carbon chains. This is particularly true for oxidized diamond and diamonds interacting with silica. A very interesting result concerns the role of stress, which reveals that compressive stresses can highly favor wear, making it even energetically favorable.

Controlling friction and wear at silica-diamond interfaces is crucial for their relevant applications in tribology such as micro-electromechanical systems and atomic force microscopes. However, the tribological performance on diamond surfaces is highly affected by the working environment where atmospheric gases are present. In this work, we investigate the effects of adsorbed oxygen on the friction and wear of diamond surfaces sliding against silica by massive ab initio molecular dynamics simulations. Different surface orientations, O-coverages, and tribological conditions are considered. The results suggest that diamond surfaces with full oxygen passivation are very effective in preventing surface adhesion, and as a result present extremely low friction and wear. At low oxygen coverage, Si-O-C bond formation was observed as well as atomistic wear initiated from C-C bond breaking at extreme pressure. The analysis of electronic structures of the configurations resulting from key tribochemical reactions clarifies the mechanisms of friction reduction and atomistic wear. Overall, our accurate in silico experiments shed light on the influence of adsorbed oxygen on the tribological properties and wear mechanisms of diamond against silica., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

This paper presents a dataset from a survey of student perceptions and experiences of quality assurance in Vietnamese higher education institutions. Data were collected from July to September 2020 using the online survey via Google Forms. The survey was sent to students via their email and social media, and there were 1323 valid responses. The data collection instrument was developed based on an international survey administered by UNESCO. The survey was designed to elicit data with respect to students' views on institutional quality policy and model, quality assurance procedures and tools, and student survey. The dataset serves as an insightful reference for institutional practitioners and policymakers in quality assurance to revise internal quality assurance policies and instruments to enhance the quality of teaching and learning. Moreover, the dataset could be of interest to other educational researchers who can use it to investigate students' understanding and viewpoints on quality assurance., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Author(s).)

Due to its unique optical, electrical, and chemical properties, tin dioxide (SnO 2 ) thin films attract enormous attention as a potential material for gas sensors, catalysis, low-emissivity coatings for smart windows, transparent electrodes for low-cost solar cells, etc . However, the low-cost and high-throughput fabrication of SnO 2 thin films without producing corrosive or toxic by-products remains challenging. One appealing deposition technique, particularly well-adapted to films presenting nanometric thickness is atomic layer deposition (ALD). In this work, several metalorganic tin-based complexes, namely, tin(IV) tert -butoxide, bis[bis(trimethylsilyl)amino] tin(II), dibutyltin diacetate, tin(II) acetylacetonate, tetrakis(dimethylamino) tin(IV), and dibutyltin bis(acetylacetonate), were explored thanks to DFT calculations. Our theoretical calculations suggest that the three last precursors are very appealing for ALD of SnO 2 thin films. The potential use of these precursors for atmospheric-pressure spatial atomic layer deposition (AP-SALD) is also discussed. For the first time, we experimentally demonstrate the AP-SALD growth of SnO 2 thin films using tin(II) acetylacetonate (Sn(acac) 2 ) and water. We observe that Sn(acac) 2 exhibits efficient ALD activity with a relatively large ALD temperature window (140-200 °C), resulting in a growth rate of 0.85 ± 0.03 Å per cyc. XPS analyses show a single Sn 3d 5/2 characteristic peak for Sn 4+ at 486.8 ± 0.3 eV, indicating that a pure SnO 2 phase is obtained within the ALD temperature window. The as-deposited SnO 2 thin films are in all cases amorphous, and film conductivity increases with the deposition temperature. Hall effect measurements confirm the n-type nature of SnO 2 with a free electron density of about 8 × 10 19 cm -3 , electron mobility up to 11.2 cm 2 V -1 s -1 , and resistivity of 7 × 10 -3 Ω cm for samples deposited at 270 °C.

While conducting sentinel surveillance of hand, foot, and mouth disease (HFMD) in Vietnam, we found a sudden increase in the prevalence of coxsackievirus A10 (CV-A10) in 2016 and CV-A2 and CV-A4 in 2017, the emergence of which has been reported recently to be associated with various clinical manifestations in other countries. However, there have been only a limited number of molecular studies on those serotypes, with none being conducted in Vietnam. Therefore, we sequenced the entire VP1 genes of CV-A10, CV-A4, and CV-A2 strains associated with HFMD in Vietnam between 2012 and 2017. Phylogenetic analysis revealed a trend of endemic circulation of Vietnamese CV-A10, CV-A4, and CV-A2 strains and the emergence of thus-far undescribed HFMD-causing lineages of CV-A4 and CV-A2. The Vietnamese CV-A10 strains belonged to a genotype comprising isolates from patients with HFMD from several other countries; however, most of the Vietnamese strains were grouped into a local lineage. Recently, emerging CV-A4 strains in Vietnam were grouped into a unique lineage within a genotype comprising strains isolated from patients with acute flaccid paralysis from various countries. New substitutions were detected in the putative BC and HI loops in the Vietnamese CV-A4 strains. Except for one strain, Vietnamese CV-A2 isolates were grouped into a unique lineage of a genotype that includes strains from various countries that are associated with other clinical manifestations. Enhanced surveillance is required to monitor their spread and to specify their roles as etiological agents of HFMD or "HFMD-like" diseases, especially for CV-A4 and CV-A2. Further studies including whole-genome sequencing should be conducted to fully understand the evolutionary changes occurring in these newly emerging strains.

In this paper, density functional theory simulations were conducted to investigate the structural adaptation of sodium borates x Na 2 O·(100- x )B 2 O 3 ( x = 25, 33, 50, and 60 mol %) during the compression/decompression between 0 and 10 GPa. The sodium borates are confined between two Fe 2 O 3 substrates and undergo the compression by reducing the gap between the two surfaces. The results reveal the borate response to the load through a two-stage transformation: rearrangement at low pressure and polymerization at high pressure. The pressure required to initiate the polymerization depends directly on the portion of fourfold-coordinated ( [4] B) boron in the sodium borates. We found that the polymerization occurs through three different mechanisms to form BO 4 tetrahedra with surface oxygen and nonbridging and bridging oxygen. The electronic structure was analyzed to understand the nature of these mechanisms. The conversions from BO 3 to BO 4 are mostly irreversible as a large number of newly formed BO 4 remain unchanged under the decompression. In addition, the formation of a sodium-rich layer can be observed when the systems were compressed to high pressure. Our simulation provides insight into sodium borate glass responses to extreme condition and the underlying electronic mechanisms that can account for these behaviors.