Preparation of Low Friction MoSex/nc-Mo Coatings Containing Spherical Mo Nanoparticles

The possibility of preparation of nanocomposite coatings consisting of a solid lubricant matrix (MoSex) and nanocrystalline metal particles (nc-Mo) was demonstrated using pulsed laser deposition from synthesized target MoSe2.The particles had spherical shapes and their sizes were about 5 - 50 nm. The content of the nc-Mo nanoparticles in the MoSex/nc-Mo coatings was varied by changing the laser irradiation regimes and the conditions of expansion of the laser plume from the target to substrate. It was established that the tribological properties of the nanocomposite coatings MoSex/nc-Mo are depended on the concentration of nanoparticles in the bulk of the coatings as well as on the structure of the coating matrix. The MoSex/nc-Mo coating with increased crystalline order of matrix obtained on a steel substrate reduced the friction coefficient to ~0.04 during steel ball sliding in air of laboratory humidity. Probable mechanisms of nanoparticle formation were proposed and a role of these particles in the wear of the nanocomposite MoSex/nc-Mo coatings was discussed

ВЛИЯНИЕ ЦЕЛЕНАПРАВЛЕННОЙ ТЕРАПИИ РАЗЛИЧНЫМИ ВИДАМИ РАСТВОРОВ НА ФУНКЦИЮ ПОЧЕК У КАРДИОХИРУРГИЧЕСКИХ ПАЦИЕНТОВ

The article describes the impact of the targeted therapy with colloid and crystalloid infusion solutions on renal function and fluid balance during the surgery and early post-surgery period in the patients who underwent aortocoronary bypass under cardio-pulmonary bypass. No differences have been found in the frequency of acute renal lesion as per AKI and the need in the substitution renal therapy. During one stage of the study the lower rates of urine neutrophil gelatinase-associated lipocalin have been observed in the group of crystalloids. The lack of confident differences in the clinical course of the post-surgery period makes the use of the balanced crystalloid solution more preferable compared to colloid solutions. В статье рассмотрено влияние целенаправленной терапии коллоидными и кристаллоиднымии инфузионными растворами на функцию почек и на баланс жидкости во время операции и в раннем послеоперационном периоде у пациентов, которым выполнено аортокоронарное шунтирование в условиях искусственного кровообращения. Не выявлено различий в частоте острого почечного повреждения по AKI и потребности в заместительной почечной терапии. На одном из этапов исследования зафиксированы более низкие показатели нейтрофильного желатиназа-ассоциированного липокалина мочи в группе кристаллоидов. Отсутствие достоверных различий в клиническом течении послеоперационного периода делает применение сбалансированного кристаллоидного раствора предпочтительнее, чем коллоидных растворов

Specific Features of Reactive Pulsed Laser Deposition of Solid Lubricating Nanocomposite Mo–S–C–H Thin-Film Coatings

This work investigates the structure and chemical states of thin-film coatings obtained by pulsed laser codeposition of Mo and C in a reactive gas (H2S). The coatings were analysed for their prospective use as solid lubricating coatings for friction units operating in extreme conditions. Pulsed laser ablation of molybdenum and graphite targets was accompanied by the effective interaction of the deposited Mo and C layers with the reactive gas and the chemical states of Mo- and C-containing nanophases were interdependent. This had a negative effect on the tribological properties of Mo–S–C–H nanocomposite coatings obtained at H2S pressures of 9 and 18 Pa, which were optimal for obtaining MoS2 and MoS3 coatings, respectively. The best tribological properties were found for the Mo–S–C–H_5.5 coating formed at an H2S pressure of 5.5 Pa. At this pressure, the x = S/Mo ratio in the MoSx nanophase was slightly less than 2, and the a-C(S,H) nanophase contained ~8 at.% S and ~16 at.% H. The a-C(S,H) nanophase with this composition provided a low coefficient of friction (~0.03) at low ambient humidity and 22 °C. The nanophase composition in Mo–S–C–H_5.5 coating demonstrated fairly good antifriction properties and increased wear resistance even at −100 °C. For wet friction conditions, Mo–S–C–H nanocomposite coatings did not have significant advantages in reducing friction compared to the MoS2 and MoS3 coatings formed by reactive pulsed laser deposition

Pulsed Laser Phosphorus Doping and Nanocomposite Catalysts Deposition in Forming a-MoSx/NP-Mo//n+p-Si Photocathodes for Efficient Solar Hydrogen Production

Pulsed laser deposition of nanostructured molybdenum sulfide films creates specific nonequilibrium growth conditions, which improve the electrocatalytic properties of the films in a hydrogen evolution reaction (HER). The enhanced catalytic performance of the amorphous a-MoSx (2 ≤ x ≤ 3) matrix is due to the synergistic effect of the Mo nanoparticles (Mo-NP) formed during the laser ablation of a MoS2 target. This work looks at the possibility of employing a-MoSx/NP-Mo films (4 and 20 nm thickness) to produce hydrogen by photo-stimulated HER using a p-Si cathode. A simple technique of pulsed laser p-Si doping with phosphorus was used to form an n+p-junction. Investigations of the energy band arrangement at the interface between a-MoSx/NP-Mo and n+-Si showed that the photo-HER on an a-MoSx/NP-Mo//n+p-Si photocathode with a 20 nm thick catalytic film proceeded according to a Z-scheme. The thickness of interfacial SiOy(P) nanolayer varied little in photo-HER without interfering with the effective electric current across the interface. The a-MoSx/NP-Mo//n+p-Si photocathode showed good long-term durability; its onset potential was 390 mV and photocurrent density was at 0 V was 28.7 mA/cm2. The a-MoSx/NP-Mo//n+p-Si photocathodes and their laser-based production technique offer a promising pathway toward sustainable solar hydrogen production

Reactive Pulsed Laser Deposition of Clustered-Type MoSx (x ~ 2, 3, and 4) Films and Their Solid Lubricant Properties at Low Temperature

We studied the tribological properties of amorphous molybdenum sulfide (MoSx) thin-film coatings during sliding friction in an oxidizing environment at a low temperature (−100 °C). To obtain films with different sulfur contents (x ~ 2, 3, and 4), we used reactive pulsed laser deposition, where laser ablation of the Mo target was performed in H2S at various pressures. The lowest coefficient of friction (0.08) was observed during tribo-testing of the MoS3 coating. This coating had good ductility and low wear; the wear of a steel counterbody was minimal. The MoS2 coating had the best wear resistance, due to the tribo-film adhering well to the coating in the wear track. Tribo-modification of the MoS2 coating, however, caused a higher coefficient of friction (0.16) and the most intensive wear of the counterbody. The MoS4 coating had inferior tribological properties. This study explored the mechanisms of possible tribo-chemical changes and structural rearrangements in MoSx coatings upon contact with a counterbody when exposed to oxygen and water. The properties of the tribo-film and the efficiency of its transfer onto the coating and/or the counterbody largely depended on local atomic packing of the nanoclusters that formed the structure of the amorphous MoSx films

Pulsed Laser Phosphorus Doping and Nanocomposite Catalysts Deposition in Forming a-MoS<em>_x</em>/NP-Mo//n⁺p-Si Photocathodes for Efficient Solar Hydrogen Production

Pulsed laser deposition of nanostructured molybdenum sulfide films creates specific nonequilibrium growth conditions, which improve the electrocatalytic properties of the films in a hydrogen evolution reaction (HER). The enhanced catalytic performance of the amorphous a-MoSx (2 ≤ x ≤ 3) matrix is due to the synergistic effect of the Mo nanoparticles (Mo-NP) formed during the laser ablation of a MoS2 target. This work looks at the possibility of employing a-MoSx/NP-Mo films (4 and 20 nm thickness) to produce hydrogen by photo-stimulated HER using a p-Si cathode. A simple technique of pulsed laser p-Si doping with phosphorus was used to form an n+p-junction. Investigations of the energy band arrangement at the interface between a-MoSx/NP-Mo and n+-Si showed that the photo-HER on an a-MoSx/NP-Mo//n+p-Si photocathode with a 20 nm thick catalytic film proceeded according to a Z-scheme. The thickness of interfacial SiOy(P) nanolayer varied little in photo-HER without interfering with the effective electric current across the interface. The a-MoSx/NP-Mo//n+p-Si photocathode showed good long-term durability; its onset potential was 390 mV and photocurrent density was at 0 V was 28.7 mA/cm2. The a-MoSx/NP-Mo//n+p-Si photocathodes and their laser-based production technique offer a promising pathway toward sustainable solar hydrogen production

Performance and Mechanism of Photoelectrocatalytic Activity of MoSx/WO3 Heterostructures Obtained by Reactive Pulsed Laser Deposition for Water Splitting

This work studies the factors that affect the efficiency of the photoelectrochemical hydrogen evolution reaction (HER) using MoSx/WO3 nano-heterostructures obtained by reactive pulsed laser deposition (RPLD) on glass substrates covered with fluorinated tin oxide (FTO). Another focus of the research is the potential of MoSx nanofilms as a precursor for MoOz(S) nanofilms, which enhance the efficiency of the photo-activated oxygen evolution reaction (OER) using the MoOz(S)/WO3/FTO heterostructures. The nanocrystalline WO3 film was created by laser ablation of a W target in dry air at a substrate temperature of 420 &deg;C. Amorphous MoSx nanofilms (2 &le; x &le; 12) were obtained by laser ablation of an Mo target in H2S gas of varied pressure at room temperature of the substrate. Studies of the energy band structures showed that for all MoSx/WO3/FTO samples, photo-activated HER in an acid solution proceeded through the Z-scheme. The highest photoelectrochemical HER efficiency (a photocurrent density ~1 mA/cm2 at a potential of ~0 V under Xe lamp illumination (~100 mW/cm2)) was found for porous MoS4.5 films containing the highest concentration of catalytically active sites attributed to S ligands. During the anodic posttreatment of porous MoSx nanofilms, MoOz(S) films with a narrow energy band gap were formed. The highest OER efficiency (a photocurrent density ~5.3 mA/cm2 at 1.6 V) was detected for MoOz(S)/WO3/FTO photoanodes that were prepared by posttreatment of the MoSx~3.2 precursor. The MoOz(S) film contributed to the effective photogeneration of electron&ndash;hole pairs that was followed by the transport of photoelectrons from MoOz(S) into the WO3 film and the effective participation of holes possessing strong oxidation ability in the OER on the surface of the MoOz(S) film