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The 2319-Al alloy is widely used in aviation industry. The crack-free 2319 alloy thin-walled sample was fabricated utilizing the laser-CMT composite additive manufacturing technique, achieving a material utilization rate of 96.43%. The impact of deposition parameters and deposition height on the microstructure and mechanical properties was studied. The microhardness of the additive manufacturing samples exhibited a gradual decrease from construction direction, with values reaching 90 HV, 78 HV, and 72 HV, respectively. The tensile property also exhibited a gradual decrease from the bottom to the top; the highest tensile strength was 296 MPa. The grain size along the construction direction of the deposited sample gradually increased, exhibiting respective sizes of 34.7 um, 36.6 um, and 45.7 um. With the increase in the height of the second phase, the segregation at the grain boundary is intensified, and as the size inside the grain increases, the corresponding density decreases. The good laser-CMT composite additively manufactured 2319 aluminum alloy samples could be obtained under the optimized deposition parameters. [ABSTRACT FROM AUTHOR]

Despite their excellent properties, the low light absorption efficiency of atomically thin transition metal dichalcogenide (TMDC) nanosheets limits their application in optoelectronics. Many efforts have been devoted to enhance the light–matter interaction of the TMDC nanosheets. Among them, coupling the TMDC nanosheet with photoactive materials has drawn extensive attention. Recently, forming one-dimensional nanoscrolls from monolayer TMDC nanosheets has also been proven to be an effective way of improving the photodetection performance of TMDC nanosheets. Herein, photoactive PbI2 nanocrystals were first deposited on a monolayer MoS2 nanosheet grown by chemical vapor deposition using a solution processing method (referred to as PbI2/MoS2). After PbI2/MoS2 was immersed into a mixture of ammonia and isopropanol, PbI2/MoS2 nanoscrolls with sizes of up to several tens of micrometers were formed in a short time. The density of PbI2 nanocrystals on the MoS2 nanosheet was highly dependent on the concentration and immersion time in PbI2 solution. Atomic force microscopy, optical microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to characterize the PbI2/MoS2 nanosheet and nanoscroll. The as-prepared PbI2/MoS2 nanosheet and nanoscroll showed photosensitivities 2 orders of magnitude higher than those of the MoS2 nanosheet and nanoscroll in visible light, which could be attributed to the type II heterointerface in the PbI2/MoS2 nanosheet and multiple PbI2/MoS2 heterointerfaces in the scrolled structure. Our work indicates that the PbI2 nanocrystal-decorated MoS2 nanoscroll could be a promising candidate for high-performance optoelectronic devices. [ABSTRACT FROM AUTHOR]

Due to their unique tubular and spiral structure, graphene and graphene oxide nanoscrolls (GONS) have shown extensive applications in various fields. However, it is still a challenge to improve the optoelectronic application of graphene and GONS because of the zero bandgap of graphene. Herein, ammonium tetrathiomolybdate ((NH4)2MoS4) was firstly wrapped into the ((NH4)2MoS4@GONS) by molecular combing the mixture of (NH4)2MoS4 and GO solution on hydrophobic substrate. After thermal annealing, the (NH4)2MoS4 and GO were converted to MoS2 nanosheets and reduced GO (RGO) simultaneously, and, thus, the MoS2@RGONS was obtained. Raman spectroscopy and high-resolution transmission electron microscopy were used to confirm the formation of MoS2 nanosheets among the RGONS. The amount of MoS2 wrapped in RGONS increased with the increasing height of GONS, which is confirmed by the atomic force microscopy and Raman spectroscopy. The as-prepared MoS2@RGONS showed much better photoresponse than the RGONS under visible light. The photocurrent-to-dark current ratios of photodetectors based on MoS2@RGONS are ~570, 360 and 140 under blue, red and green lasers, respectively, which are 81, 144 and 35 times of the photodetectors based on RGONS. Moreover, the MoS2@RGONS-based photodetector exhibited good power-dependent photoresponse. Our work indicates that the MoS2@RGONS is expected to be a promising material in the fields of optoelectronic devices and flexible electronics. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenide (TMD) nanosheets (e.g., MoS2) with metallic phase (1T or 1T´ phase) have been proven to exhibit superior performances in various applications as compared to their semiconducting 2H-phase counterparts. However, it remains unclear how the crystal phase of 2D TMD nanosheets affects their sonodynamic property. In this work, we report the preparation of MoS2 nanosheets with different phases (metallic 1T/1T´ or semiconducting 2H) and exploration of its crystal-phase effect on photothermal-enhanced sonodynamic antibacterial therapy. Interestingly, the defective 2D MoS2 nanosheets with high-percentage metallic 1T/1T´ phase (denoted as M-MoS2) present much higher activity towards the ultrasound-induced generation of reactive oxygen species (ROS) as compared to the semiconducting 2H-phase MoS2 nanosheets. More interestingly, owing to its metallic phase-enabled strong absorption in the near-infrared-II (NIR-II) regime, the ultrasound-induced ROS generation performance of the M-MoS2 nanosheets can be further enhanced by the photothermal effect under a 1064 nm laser irradiation. Thus, after modifying with polyvinylpyrrolidone, the M-MoS2 nanosheets can be used as an efficient sonosensitizer for photothermal-enhanced sonodynamic bacterial elimination under ultrasound treatment combining with NIR-II laser irradiation. This study demonstrates that metallic MoS2 nanosheets can be used as a promising sonosensitizer for antibacterial therapy, which might be also promising for cancer therapies. [ABSTRACT FROM AUTHOR]

Direct catalytic oxidation of alcohols to carboxylic acids is very attractive, but economical catalysis systems have not yet been well established. Here, we show that a pure inorganic ligand-supported chromium compound, (NH4)3[CrMo6O18(OH)6] (simplified as CrMo6), could be used to effectively promote this type of reaction in the presence of CO2. In almost all cases, oxidation of various alcohols (aromatic and aliphatic) could be achieved under mild conditions, and the corresponding carboxylic acids can be achieved in high yield. The chromium catalyst 1 can be reused several times with little loss of activity. Mechanism study and control reactions demonstrate that the acidification proceeds via the key oxidative immediate of aldehydes. [ABSTRACT FROM AUTHOR]

Direct catalytic oxidation of alcohols to carboxylic acids is very attractive, but economical catalysis systems have not yet been well established. Here, we show that a pure inorganic ligand-supported chromium compound, (NH4)3[CrMo6O18(OH)6] (simplified as CrMo6), could be used to effectively promote this type of reaction in the presence of CO2. In almost all cases, oxidation of various alcohols (aromatic and aliphatic) could be achieved under mild conditions, and the corresponding carboxylic acids can be achieved in high yield. The chromium catalyst 1 can be reused several times with little loss of activity. Mechanism study and control reactions demonstrate that the acidification proceeds via the key oxidative immediate of aldehydes. [ABSTRACT FROM AUTHOR]

This paper proposes a six-pole radial-axial hybrid magnetic bearing (RAHMB) used in a flywheel system. The radial and axial bias fluxes are generated by one permanent magnet and the radial control coils are driven by a three-phase converter. So, it has the advantages of compact structure, low power consumption and simple driver. First, the work principle is introduced. Then, the mathematical model is built. The force-current characteristics with different eccentricities, the coupling between radial two degrees of freedom (DOF) and the coupling between radial and axial DOF are analyzed based on the analytical model. Finally, the analyses are validated by 3D finite element analysis in the Maxwell software. The results have shown that the coupling between radial and axial DOF is very small. However, the force-current curves of radial two DOFs turn out to be nonlinear and coupled with the increase of rotor eccentricity. [ABSTRACT FROM AUTHOR]

An efficient oxidation and functionalization of C–H bonds with an inorganic-ligand supported iron catalyst and hydrogen peroxide to prepare the corresponding ketones was achieved using the bromide ion as a promoter. Preliminary mechanistic investigations indicated that the bromide ion can bind to FeMo6 to form a supramolecular species (FeMo6·2Br), which can effectively catalyze the reaction. [ABSTRACT FROM AUTHOR]