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In order to investigate the effect of different substrate surface roughness on the friction and wear properties of amorphous carbon films, and improve the tribological properties of the 2Cr13 sample surface under 601EF lubricating grease lubrication, the methods such as machining, polishing and other techniques were employed to prepare different surface roughness on the surface of 2Cr13 samples. Subsequently, amorphous carbon thin films were prepared on the surface of samples with different roughness by magnetron sputtering. The friction and wear properties of amorphous carbon films and silicon nitride balls under 601EF lubricating grease lubrication were investigated through ball-disc contact friction and wear tests, and the wear places were analyzed by optical microscopy. Results showed that the Si3N4 balls that rubbed against the substrate surface all presented a clear platform, while the substrate surface did not display any obvious grinding marks. The samples with the Ra range of 0.20～0.75 μm on the coupling ball had the smaller wear amount, the wear spot area range was 0.152～0.165 mm2, and the wear form was adhesive wear. By contrast, the samples with the Ra range of 0.95～3.19 μm had more wear amount on the coupling ball, the wear spot area ranging from 0.228～0.275 mm2, and there were furrow-like wear marks, which indicated more serious wear. Under the same operating conditions, as the surface roughness of the substrate increased, the starting and average friction coefficients between the two friction pairs, as well as the wear amount of Si3N4 balls, all showed a trend of first decreasing, then increasing, and then decreasing. When the Ra was 0.56 μm, the tribological performance of the amorphous carbon film was the best, and the friction curve was relatively stable, with an average friction coefficient of 0.162, and the wear amount of its coupling ball was the smallest, 0.152 mm2. In general, the surface roughness of the substrate affected the tribological performance of amorphous carbon films, and the surface with good anti friction properties could be obtained by preparing appropriate roughness on the substrate surface via the means of machining, polishing, etc.

Antimicrobial resistance (AMR) from pathogenic bacterial biofilms has become a global health issue while developing novel antimicrobials is inefficient and costly. Combining existing multiple drugs with enhanced efficacy and/or reduced toxicity may be a promising approach to treat AMR. D‐amino acids mixtures coupled with antibiotics can provide new therapies for drug‐resistance infection with reduced toxicity by lower drug dosage requirements. However, iterative trial‐and‐error experiments are not tenable to prioritize credible drug formulations, owing to the extremely large number of possible combinations. Herein, a new avenue is provide to accelerate the exploration of desirable antimicrobial formulations via high‐throughput screening and machine learning optimization. Such an intelligent method can navigate the large search space and rapidly identify the D‐amino acid mixtures with the highest anti‐biofilm efficiency and also the synergisms between D‐amino acid mixtures and antibiotics. The optimized drug cocktails exhibit high antimicrobial efficacy while remaining non‐toxic, which is demonstrated not only from in vitro assessments but also the first in vivo study using a lung infection mouse model. [ABSTRACT FROM AUTHOR]

Friction as a fundamental physical phenomenon dominates nature and human civilization, among which the achievement of molecular rolling lubrication is desired to bring another breakthrough, like the macroscale design of wheel. Herein, an edge self-curling nanodeformation phenomenon of graphite nanosheets (GNSs) at cryogenic temperature is found, which is then used to promote the formation of graphite nanorollers in friction process towards molecular rolling lubrication. The observation of parallel nanorollers at the friction interface give the experimental evidence for the occurrence of molecular rolling lubrication, and the graphite exhibits abnormal lubrication performance in vacuum with ultra-low friction and wear at macroscale. The molecular rolling lubrication mechanism is elucidated from the electronic interaction perspective. Experiments and theoretical simulations indicate that the driving force of the self-curling is the uneven atomic shrinkage induced stress, and then the shear force promotes the intact nanoroller formation, while the constraint of atomic vibration decreases the dissipation of driving stress and favors the nanoroller formation therein. It will open up a new pathway for controlling friction at microscale and nanostructural manipulation., (© 2024. The Author(s).)