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Bacteria are an old concern to human health, as they are responsible for nosocomial infections, and the number of antibiotic-resistant microorganisms keeps growing. Copper is known for its intrinsic biocidal properties, and therefore, it is a promising material to combat infections when added to surfaces. However, its biocidal properties in the presence of light illumination have not been fully explored, especially regarding the use of microsized particles since nanoparticles have taken over all fields of research and subjugated microparticles despite them being abundant and less expensive. Thus, the present work studied the bactericidal properties of metallic copper particles, in microscale (CuMPs) and nanoscale (CuNPs), in the absence of light and under white LED light illumination. The minimum bactericidal concentration (MBC) of CuMPs against Staphylococcus aureus that achieved a 6-log reduction was 5.0 and 2.5 mg mL -1 for assays conducted in the absence of light and under light illumination, respectively. Similar behavior was observed against Escherichia coli . The bactericidal activity under illumination provided a percentage increase in log reduction values of 65.2% for S. aureus and 166.7% for E. coli when compared to the assays under dark. This assay reproduced the testing CuNPs, which showed superior bactericidal activity since the concentration of 2.5 mg mL -1 promoted a 6-log reduction of both bacteria even under dark. Its superior bactericidal activity, which overcame the effect of illumination, was expected once the nanoscale facilitated the interaction of copper within the surface of bacteria. The results from MBC were supported by fluorescence microscopy and atomic absorption spectroscopy. Therefore, CuMPs and CuNPs proved to have size- and dose-dependent biocidal activity. However, we have shown that CuMPs photoactivity is competitive compared to that of CuNPs, allowing their application as a self-cleaning material for disinfection processes assisted by conventional light sources without additives to contain the spread of pathogens.

This study presents a comparison of H 2 and D 2 passivation on Si(100) under simultaneous Xe + ion bombardment. The impact of Xe + ions causes significant damage to the substrate surface, leading to an increase in H 2 (D 2 ) retention as Si-H (Si-D) bonds. The ion bombardment conditions are precisely controlled using a Kaufman ion gun. The atomic concentrations on the surface of the sample were investigated by quasi- in situ X-ray photoelectron spectroscopy. A simple methodology is employed to estimate the H (D) chemical concentration and the cover ratio of the sample, with regard to the oxygen concentration through residual water chemisorption present in the vacuum vessel. Differences in passivation are expected when using H 2 or D 2 atmospheres because their retained scission energies and physisorption properties differ. The results indicate an increase of the sticking coefficient for D 2 and H 2 under the ion bombardment. It is also found that the flux of H 2 (D 2 ) impinging on the surface contributes to play an important role in the whole process. Finally, a model is proposed to describe the phenomenon of the passivation of Si under Xe + ion bombardment in the presence of H 2 (D 2 ).

Objective: To determine if proximal and distal neuromuscular parameters (EMG amplitude and median frequency - MDF) can predict frontal plane kinematics during single-leg landing., Study Design: Cross sectional study., Setting: Laboratory., Participants: Fifteen participants (7 female) performed six single-leg landings with measures of frontal plane kinematics and EMG obtained 230 ms after first foot contact, totalizing 90 landings., Main Outcome Measures: (i) 2D hip adduction [hip ADD] and knee frontal plane projection angle [knee FPPA]; (ii) EMG amplitude and MDF of gluteus medius [GMed], tensor fascia latae [TFL], peroneus longus [PL] and tibialis anterior [TA]., Results: We observed that MDF of TA was a significant predictor of hip ADD (p = 0.037; β = -0.049 Hz; R 2 c = 0.30). Also, MDF of PL was significant predictor of knee FPPA (p = 0.043; β = 0.042 Hz; R 2 c = 0.37). Hip muscles and EMG amplitude parameters were not considered predictors of frontal plane kinematics., Conclusion: The firing frequency of ankle muscles predicted the variance of hip and knee frontal plane kinematics during single-leg landing., Competing Interests: Declaration of competing interest None., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

In dry sliding, the coefficient of friction depends on the material pair and contact conditions. If the material and operating conditions remain unchanged, the coefficient of friction is constant. Obviously, we can tune friction by surface treatments, but it is a nonreversible process. Here, we report active control of friction forces on TiO 2 thin films under UV light. It is reversible and stable and can be tuned/controlled with the light wavelength. The analysis of atomic force microscopy signals by wavelet spectrograms reveals different mechanisms acting in the darkness and under UV. Ab initio simulations on UV light-exposed TiO 2 show a lower atomic orbital overlapping on the surface, which leads to a friction reduction of up to 60%. We suggest that photocontrol of friction is due to the modification of atomic orbital interactions from both surfaces at the sliding interface.

The role played by oxygen vacancies and rare earth (RE) elements in the anatase-to-rutile (A-R) phase transformation of titanium dioxide (TiO 2 ) is still a matter of controversy. Here, we report the A-R transformation of TiO 2 thin solid films as obtained by ion beam sputtering a RE-decorated titanium target in an oxygen-rich atmosphere. The samples correspond to undoped, single-doped (Sm, Tm, and Tb), and codoped (Sm:Tb, Sm:Tm, and Sm:Tb:Tm) TiO 2 films. In the as-prepared form, the films are amorphous and contain ∼0.5 at. % of each RE. The structural modifications of the TiO 2 films due to the RE elements and the annealing treatments in an oxygen atmosphere are described according to the experimental results provided by Raman scattering, X-ray photoelectron spectroscopy, and optical measurements. The A-R transformation depends on both the annealing temperature and the characteristics of the undoped, single-doped, and codoped TiO 2 films. As reported in the literature, the A-R transformation can be inhibited or enhanced by the presence of impurities and is mostly related to energetic contributions. The experimental results were analyzed, considering the essential and stabilizing role of the entropy of mixing in the A-R transformation due to the introduction of more and multiple quantum states originated in vacancies and impurities in the anatase phase., Competing Interests: The authors declare no competing financial interest., (© 2020 American Chemical Society.)

We report on a new route to grow epitaxial copper (Cu) ultra-thin films (up to 150 nm thick) at ambient temperature on Si(001) wafers covered with native oxide without any prior chemical etching or plasma cleaning of the substrate. It consists of a single-step deposition process using high power impulse magnetron sputtering (HiPIMS) and substrate biasing. For a direct current (DC) substrate bias voltage of -130 V, Cu/Si heteroepitaxial growth is achieved by HiPIMS following the Cu(001) [100]//Si(001) [110] orientation, while under the same average deposition conditions, but using conventional DC magnetron sputtering, polycrystalline Cu films with [111] preferred orientation are deposited. In addition, the intrinsic stress has been measured in situ during growth by real-time monitoring of the wafer curvature. For this particular HiPIMS case, the stress is slightly compressive (-0.1 GPa), but almost fully relaxes after growth is terminated. As a result of epitaxy, the Cu surface morphology exhibits a regular pattern consisting of square-shaped mounds with a lateral size of typically 150 nm. For all samples, X-ray diffraction pole figures and scanning/transmission electron microscopy reveal the formation of extensive twinning of the Cu {111} planes.