Evidence of Spin Frustration in a Vanadium Diselenide Monolayer Magnet

Monolayer VSe₂, featuring both charge density wave and magnetism phenomena, represents a unique van der Waals magnet in the family of metallic 2D transition‐metal dichalcogenides (2D‐TMDs). Herein, by means of in situ microscopy and spectroscopic techniques, including scanning tunneling microscopy/spectroscopy, synchrotron X‐ray and angle‐resolved photoemission, and X‐ray absorption, direct spectroscopic signatures are established, that identify the metallic 1T‐phase and vanadium 3d¹ electronic configuration in monolayer VSe₂ grown on graphite by molecular‐beam epitaxy. Element‐specific X‐ray magnetic circular dichroism, complemented with magnetic susceptibility measurements, further reveals monolayer VSe₂ as a frustrated magnet, with its spins exhibiting subtle correlations, albeit in the absence of a long‐range magnetic order down to 2 K and up to a 7 T magnetic field. This observation is attributed to the relative stability of the ferromagnetic and antiferromagnetic ground states, arising from its atomic‐scale structural features, such as rotational disorders and edges. The results of this study extend the current understanding of metallic 2D‐TMDs in the search for exotic low‐dimensional quantum phenomena, and stimulate further theoretical and experimental studies on van der Waals monolayer magnets.     

Effects of combination modes of favorable growth unit of Al（OH）3 crystals precipitating on Van der Waals and chemical bond force

The dipole moment, total energy, atomic charge, orbital population and orbital energy of four representative combination models of the favorable growth unit Al6（OH）18 （H2O）6 of Al（OH）3 crystals precipitating are calculated by ab initio at RHF/STO-3G, RHF/3-21G, RHF/6-31G levels and DFT at RB3LYP/STO-3G, RB3LYP/ 3-21G, RB3LYP/6-31G levels with Dipole ＆ Sphere solvent model. The effect of various combination models on Van der Waals force is analyzed using dipole moment and molecular radius, and that on chemical bond force is analyzed using total energy, orbital population and orbital energy.     

一种简单的微球姿态操作模型

分析了在操作环境中微球受力的情况，并结合Hertz接触理论，建立了微球姿态操作的力学模型和数学模型；对模型求解，得出了对微球姿态操作所需的操作力和操作角之间的关系，分析了考虑范德华力和忽略范德华力时的不同，说明了范德华力在微球姿态操作中的重要影响，为进一步试验研究提供了相应的依据。     

Growth and Luminescence of Polytypic InP on Epitaxial Graphene

Van der Waals epitaxy is an attractive alternative to direct heteroepitaxy where the forced coherency at the interface cannot sustain large differences in lattice parameters and thermal expansion coefficients between the substrate and the epilayer. Herein, the growth of monocrystalline InP on Ge and SiO₂/Si substrates using graphene as an interfacial layer is demonstrated. Micrometer‐sized InP crystals are found to grow with interfaces of high crystalline quality and with different degrees of coalescence depending on the growth conditions. Some InP crystals exhibit a polytypic structure, consisting of alternating zinc‐blende and wurtzite phases, forming a type‐II homojunction with well (barrier) width of about 10 nm. The optical properties, investigated using room temperature nano‐cathodoluminescence, indicate the signatures of the direct optical transitions at 1.34 eV across the gap of the zinc‐blende phase and the indirect transitions at ≈ 1.31 eV originating from the alternating zinc‐blende and wurtzite phases. Additionally, the InP nanorods, found growing mainly on the graphene/SiO₂/Si substrate, show optical transition across the gap of the wurtzite phase at ≈ 1.42 eV. This demonstration of InP growth on graphene and the correlative study between the structure and optical properties pave the way to develop hybrid structures for potential applications in integrated photonic and optoelectronic devices.     

Integrating Co3O4 nanoparticles with MnO2 nanosheets as bifunctional electrocatalysts for water splitting

Developing high-efficiency and low-cost electrocatalyst is significant for the application of water splitting technology. Herein, Co₃O₄ nanoparticles and MnO₂ nanosheets are separately synthesized and subsequently assembled into a unique 0/2-dimensional heterostructure via van der Waals interactions. The consequent composites expose abundant accessible active sites and expedite the reaction kinetics, which can be testified by the superiorities in Tafel slope, exchange current density and double-layer capacitance, only requiring overpotentials of 355 and 129 mV for oxygen and hydrogen evolution reactions in 1.0 M KOH at 10 mA cm^?2, respectively. Moreover, a cell voltage of 1.660 V can drive the electrolyzer at 10 mA cm^?2. Benefitted from robust integration, the original aggregation and restacking of individual materials have been overcome, thereby leading to superior elelctrocatalysis durability. This facile and universal strategy may inspire the researchers on the design and construction of advanced functional composites.     

一种基于胆固醇衍生物的两亲分子的合成及其聚集行为

合成了以胆固醇为疏水基、双甘肽为亲水基的两亲分子N-胆固醇甲酰基双甘肽钾盐(Chol-GG-K)。利用透射电镜(TEM)、激光共聚焦显微镜(CLSM)等手段研究了该分子在水中的聚集行为,发现其在水中形成了多分散的囊泡结构。胆固醇的范德华力形成强疏水作用和聚集能力,亲水基的氢键作用也是产生聚集作用的驱动力。     

Contact properties determination of macroscopic fine disperse glass particles via compression tests in normal direction

The paper describes the deformation behavior of spherical, dry and non-porous particles during a single particle compression test in normal direction. Therefore a compression tester was built. Industrial used soda lime glass particles with two macroscopic fine disperse sizes (d_1,50,3 = 284.30 μm and d_2,50,3 = 513.20 μm) were applied as model material to investigate the micromechanical contact behavior. In order to influence the elastic-plastic contact properties of particles, the surfaces were altered with chemical modification by means of silanization.The determination of various micromechanical contact properties (e.g. adhesion force, modulus of elasticity and contact stiffness) was carried out model-based with the contact model ‘stiff particles with soft contacts’ by means of a back-calculation.It could be shown that the model-based determination of material properties was a good alternative compared to the comprehensive tensile tests and pull-off force measurements.In addition to the gained normal force-displacement data in normal direction, the friction limits for tangential loading and rolling with the load-dependent adhesion force were model-based determined.     

Gelatinization and retrogradation characteristics of wheat (Rosella) starch

The non-Newtonian behavior and elastic modulus of wheat (Rosella) starch solutions after preparation, and storage at 25 °C and 4 °C for 24 h were measured with a rheogoniometer. The flow curves of wheat starch showed plastic behavior above 4.0% solution. After storage at 4 °C in 4.0% solution, elastic modulus increased at low temperature and showed a constant value with increase in temperature. Elastic modulus increased upon addition of urea (4.0 M) at low temperature and remained constant up to 60 °C. Elastic modulus of Rosella also increased in 0.05 M NaOH solution after storage. Rheological characteristics of Rosella starch differed from those of rice starches. This might be caused by difference in structure of amylopectin and large amount of amylose content on starch.     

A new concept for augmented van der Waals equations of state

A novel approach to perturbed equations of state for simple fluids is presented and its advantages over the traditional perturbed hard sphere equations are demonstrated by its application to several model fluids. The approach is based on a short range Yukawa reference which incorporates, in addition to repulsive interactions, also attractive interactions at short separations. The considered models of common interest are the Sutherland, Lennard-Jones, and EXP6 fluids. It is shown that using the proposed approach the reference system captures a good deal of properties of the studied fluids and that an accurate equation of state can be obtained using only the crude mean field (augmented van der Waals) approach.