Effects of Yttrium Doping on the Performance of Ru-Based Catalysts for Hydrogenation of Fatty Acid Methyl Ester

The highly dispersed supported ruthenium-yttrium (Ru-Y) bimetallic catalysts were prepared by impregnation method and their catalytic performance for hydrogenation of ester was fully investigated. The catalyst was characterized by X-ray diffraction and field emission scanning electron microscopy. The results show that the average particle diameter of the bimetallic crystallites was less than 10 nm. The effects of the reaction temperature, the hydrogen pressure, the amount of catalyst and the proportion of yttrium in catalyst on the hydrogenation of ester were studied. The experimental results show that the introduction of yttrium not only changed the chemical and textural properties of ruthenium-based catalyst but also controlled the formation of Ru-Y alloy. The Ru-Y catalyst (Ru-2%Y/TiO2) exhibited high catalytic activity and good selectivity towards the higher alcohols. Under optimal reaction conditions of 240°C and 5 MPa hydrogen pressure, the conversion of palm oil esters was above 93.4% while the selectivity towards alcohol was above 99.0%.

Multidimensional optical tweezers synthetized by rigid-body emulated structured light

Structured light with more extended degrees of freedom(DoFs)and in higher dimensions is increasingly gaining traction and leading to breakthroughs such as super-resolution imaging,larger-capacity communication,and ultraprecise optical trapping or tweezers.More DoFs for manipulating an object can access more maneuvers and radically increase maneuvering precision,which is of significance in biology and related microscopic detection.However,manipulating particles beyond three-dimensional(3D)spatial manipulation by using current all-optical tweezers technology remains difficult.To overcome this limitation,we theoretically and experimentally present six-dimensional(6D)structured optical tweezers based on tailoring structured light emulating rigid-body mechanics.Our method facilitates the evaluation of the methodology of rigid-body mechanics to synthesize six independent DoFs in a structured optical trapping system,akin to six-axis rigid-body manipulation,including surge,sway,heave,roll,pitch,and yaw.In contrast to previous 3D optical tweezers,our 6D structured optical tweezers significantly improved the flexibility of the path design of complex trajectories,thereby laying the foundation for next-generation functional optical manipulation,assembly,and micromechanics.

Microstructure evolution, Cu segregation and tensile properties of CoCrFeNiCu high entropy alloy during directional solidification

CoCrFeNiCu(equiatomic ratio)samples(?8 mm)were directionally solidified at different velocities(10,30,60 and 100μm/s)to investigate the relationship between solidification velocity and microstructure formation,Cu micro-segregation as well as tensile properties.The results indicate that the morphology of the solid-liquid(S-L)interface evolves from convex to planar and then to concave with the increase of solidification velocity.Meanwhile,the primary and the secondary dendritic arm spacings decrease from100μm to 10μm and from 20μm to 5μm,respectively.They are mainly influenced by the axial heat transfer and grain competition growth.During directional solidification,element Cu is repelled from the FCC phase and accumulates in the liquid owe to its positive mixing enthalpy with other elements.Tensile testing results show that the ultimate tensile strength(UTS)gradually increases from 400 MPa to 450 MPa,and the strain of the specimen prepared at the velocity of 60μm/s is higher than those of others.The fracture mode of all specimens is the mixed fracture containing both ductile fracture and brittle fracture,in which ductile fracture plays a fundamental role.In addition,the brittle fracture is induced by Cu segregation.The improvement of UTS is resulted from columnar grain boundary strengthening.