Lunar cratering asymmetries with high lunar orbital obliquity and inclination of the Moon

Accurate estimation of cratering asymmetry on the Moon is crucial for understanding Moon evolution history.Early studies of cratering asymmetry have omitted the contributions of high lunar obliquity and inclination.Here,we include lunar obliquity and inclination as new controlling variables to derive the cratering rate spatial variation as a function of longitude and latitude.With examining the influence of lunar obliquity and inclination on the asteroids population encountered by the Moon,we then have derived general formulas of the cratering rate spatial variation based on the crater scaling law.Our formulas with addition of lunar obliquity and inclination can reproduce the lunar cratering rate asymmetry at the current Earth-Moon distance and predict the apex/ant-apex ratio and the pole/equator ratio of this lunar cratering rate to be 1.36 and 0.87,respectively.The apex/ant-apex ratio is decreasing as the obliquity and inclination increasing.Combining with the evolution of lunar obliquity and inclination,our model shows that the apex/ant-apex ratio does not monotonically decrease with Earth-Moon distance and hence the influences of obliquity and inclination are not negligible on evolution of apex/ant-apex ratio.This model is generalizable to other planets and moons,especially for different spin-orbit resonances.

Effect of Mn and Mo on microstructure and mechanical properties of Al-Si-Cu-Mg-0.6Fe alloy

Effect of different Mn and Mo contents on microstructure and mechanical properties of Al-Si-Cu-Mg-0.6Fe alloy was studied.Results indicate that the increase of Mo and decrease of Mn lead to a decrease in the size of theα-Al_(15)(FeMnMo)_(3)Si_(2) phase formed during solidification.Theα-Al_(15)(FeMnMo)_(3)Si_(2) phase reaches a minimum value of about 16.3μm at 0.2wt.%Mo and 0.1wt.%Mn addition.After solution treatment,theα-Al(FeMnMo)Si dispersed phase is precipitated.When only Mn is added,theα-Al(FeMnMo)Si dispersed phase mainly distributes near the grain boundaries,while when only Mo is added,it primarily distributes in the central region of the matrix.When both Mn and Mo are added,the dispersed phase has a larger and denser dispersed region and is uniformly distributed near the Al matrix and grain boundaries.Moreover,the best overall mechanical properties of the alloy are obtained with the combined addition of 0.1wt.%Mn and 0.2wt.%Mo,due to the smaller size ofα-Al_(15)(FeMnMo)_(3)Si_(2) phase and the larger area fraction and higher density of theα-Al(FeMnMo)Si dispersed phase.The yield strength,ultimate tensile strength,and elongation are respectively improved 67.7 MPa,48.5 MPa and 5.3%,respectively,compared to that of the alloy with only 0.3wt.%Mn.

Collaboratively enhancing electrochemical properties of LiNi_(0.83)Co_(0.11)Mn_(0.06)O_(2) through doping and coating of quadrivalent elements

Ni-rich layered oxides(Ni>80%)with high energy density have become a mainstream cathode material for Li-ion batteries.However,irreversible phase transitions and interface instability are deep-seated challenges in commercializing Ni-rich materials.This study used a collaborative modification strategy involving doping and coating with quadrivalent elements to construct Ni-rich materials.In particular,introducing tetravalent Zr makes the valence change of Ni(2+to 4+)more accessible to complete spontaneously during the charging and discharging processes,which significantly suppresses the cationic mixing and irreversible phase transition(H2?H3).Combining the strategy of constructing CeO_(2) coatings on the surface and interfacial spinel-like phases improves the Li+diffusion kinetics and interfacial stability.Simultaneously,part of the strongly oxidizing four-valence Ce^(4+)diffuses to the surface layer,further increasing the average valence state of Ni.Therefore,LiNi_(0.83)Co_(0.11)Mn_(0.06)O_(2)(NCM)-Zr@Ce achieves 78.5%outstanding retention at1.0C after 200 cycles within 3.0-4.3 V compared to unmodified NCM with 41.4%retention.The improved cyclic stability can be attributed to the collaborative modification strategy of the quadrivalent elements,which provides an effective synergistic modification strategy for developing high-performance Li-ion battery cathode materials.