Modern Physics Letters B

In this paper, cobalt concentration on the interface mechanism between diamond coating and cemented carbide substrate was used by first-principles calculation and experimental study. The interface model was built and analyzed. The effect of pretreatment time on the Co concentration on the surface of cemented carbide was studied. The relationship between the bond strength of the WC–Co/diamond interface was analyzed based on energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), Raman spectroscopy and indentation. The simulation results showed that the bonding strength of the WC–Co/diamond interface increased gradually with the decrease of Co concentration and has an extreme value. The test results showed that the pretreatment decobaltization time was 20 min and the bonding strength of the membrane substrate is good. What was more, the results of EDX, SEM, Raman, indentation confirmed this conclusion.

In this paper, the spin ladder consisting of two antiferromagnetic Heisenberg legs is investigated by means of the density matrix renormalization group method with its matrix product state form. The energy density and bipartite entanglement measured by concurrence are calculated, the effects of interleg couplings and open boundary condition on entanglement distributions are discussed in detail when the interleg couplings are ferro- and antiferromagnetic, respectively. We found that the entanglements are mainly distributed in legs and diagonals when the interleg couplings are ferromagnetic and in rungs when the couplings are antiferromagnetic. Furthermore, the intraleg entanglements are more affected by the dimerization caused by open boundary than interleg ones. Specifically, that dimerization will be weakened by the interleg couplings, and the entanglements are distributed more uniformly.

In this work, we investigate the time-dependent MHD free convection of Casson fluid across a vertical semi-infinite plate fitted inside a permeable medium, along with viscous dissipation, radiation absorption, and Soret effect by using several non-dimensional variables. The characteristics of a variety of elements influencing the flow phenomenon are examined using the Casson fluid model. The governing dimensional partial differential equations are transformed into an ordinary differential equation set by introducing the similarity variables. The reduced model is numerically solved via the Galerkin finite element method. The non-dimensional equations with suitable boundary conditions can be mathematically simplified using the efficient Galerkin finite element approach. The restrictions are shown numerically and graphically, and their effects on temperature, velocity, species concentration, and rate coefficients are all shown. This study is to present the influence of radiation absorption along with viscous dissipation on the heat transfer phenomenon. For different flow parameter estimations, graphs are generated for various flow profiles as well as skin friction coefficients. The Nusselt (Nu) and Sherwood (Sh) quantities are also demonstrated via graphs.

The temperature dependences of the conductivity and permittivity of the Ag₈GeSe₆ compound have been studied in direct and alternating electric fields. This phenomenon is associated with the process of charge accumulation at the boundary of the sample with ionic conductivity and the blocking electrode, and the formation of a double electric layer. The observed dielectric relaxation is associated with the transition of the crystal to the superionic state. It has been established that hopping conduction with a variable hopping length over localized states near the Fermi level takes place in an Ag₈GeSe₆ crystal.

Zn (1, 3, 5, 7 mol.%): Dy: LiNbO₃ crystals were prepared by the traditional vertical pull-up method. The effective segregation coefficients of ${\text{Zn}}^{2+}$ and ${\text{Dy}}^{3+}$ were found to decrease with increasing ${\text{Zn}}^{2+}$ concentration using ICP-AES analysis test. The lattice size was found to increase first and then decrease using XRD analysis test. The absorption spectrum was found blue shifted and produced two peaks using IR. Research shows that when the Zn content reaches or exceeds the threshold value, ${\mathrm{\text{Nb}}}_{\mathrm{\text{Li}}}^{4+}$ is replaced completely, and Zn occupies the Li and Nb positions of lithium niobate, thus introducing the non-intrinsic defect ${\mathrm{\text{Zn}}}_{\mathrm{\text{Li}}}^{+}$ and ${\mathrm{\text{Zn}}}_{\mathrm{\text{Nb}}}^{3-}$. Both defects are able to form ${\mathrm{\text{3Zn}}}_{\mathrm{\text{Li}}}^{+}-{\mathrm{\text{Zn}}}_{\mathrm{\text{Nb}}}^{3-}$ charge self-compensating defect groups and inhibit the charge transport process and thus will greatly increase the photodamage resistance.

As an important auxiliary equipment for ships, the stable operation of centrifugal pumps has a significant impact on the safe operation of ships, so monitoring the operation of marine centrifugal pumps is particularly urgent. In this paper, a marine centrifugal pump is studied for four cases: the normal state, the initial stages of broken state, the intermediate stages of broken state, and the late stages of broken state. The Delayed Detached Eddy Simulation (DDES) with a nonlinear eddy viscosity model is used for the nonstationary calculation of the whole channel, aiming to study the performance of the centrifugal pump in the broken state. A comprehensive analysis of the hydrodynamic characteristics of the centrifugal pump, such as external characteristics, flow situation, pressure pulsation, and flow analysis based on the proper orthogonal decomposition (POD) method, was carried out. Taken together, these results suggest that as the number of broken blades increases, the corresponding head and efficiency gradually decrease. Blade loss mainly affects the uniformity and stability of the flow field, so that the centrifugal pump performance loss increases, which in turn causes the centrifugal pump head and efficiency to decline. It also leads to an increase in radial force during operation, which in turn causes an increase in the amplitude of pump vibration. The results of the study provide some references for the fault diagnosis of centrifugal pumps.

The room temperature gas sensors have always been an important research direction of the gas sensor, and the room temperature gas sensors without the assistance of the light is more valuable. The SnO₂ nanoparticles were synthesized by hydrothermal method, which showed good formaldehyde sensitivity, had the advantages of low test temperature, only $100^{\circ }$C, good formaldehyde selectivity, and especially the good response to formaldehyde at room temperature. The nanostructure and gas-sensing properties were characterized by scanning electron microscopy, EDS mapping, nitrogen physical adsorption, and X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and WS-60B gas-sensing measurement system. Compared with the reported research results, we carefully discuss the physical mechanism of the SnO₂ formaldehyde sensor with low operating temperature and good formaldehyde selectivity in this paper.

The effects of gradient grain size and temperature on the mechanical properties of nanocrystalline nickel were studied by the molecular dynamics method, and the microstructure change process of size gradient nanocrystalline nickel under tensile load was characterized by Common Neighbor Analysis (CNA). The research results show that dislocations tend to generate stress concentration in small-sized grains during stretching, so the plastic deformation of the material always occurs in small-sized grains first. At the same time, through Dislocation Analysis (DXA), it was found that Shockley dislocation is the main factor affecting its mechanical properties, and the interaction between dislocations provides a certain contribution to the strength of the metal. In addition, yield strength, maximum tensile stress, and Young’s modulus all decrease with increasing temperature, and the grain boundary atomic content and the degree of disorder are greatly increased. During the stretching process, the number of dislocations is greatly reduced, which leads to a reduction of their interactions, which is the reason for the reduction of the mechanical properties of the material. The above research results have positive meaning for the design of gradient nanocrystalline materials, and provide reference and help for the improvement of nanomaterial properties.