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Background Deep circumflex iliac artery (DCIA)-vascularized iliac graft transposition is a method for treating femoral head osteonecrosis but with inconsistent efficacy. We aim to improve the method of this surgery by recommending the optimal location of the iliac pedicle to satisfy the vascular length for transposition and the blood supply of the vascularized iliac graft. Methods The DCIA and its surrounding tissues were assessed on computed tomography angiography images for 100 sides (left and right) of 50 patients. The length of the vascular pedicle required for transposition and the length of the pedicle at different iliac spine positions were compared. The diameter and cross-sectional area of the DCIA and the distance between the DCIA and iliac spine were measured at different points to assess blood supply. We also compared differences in sex and left–right position. Results The diameter and cross-sectional area of the DCIA gradually decreased after crossing the anterior superior iliac spine (ASIS), and it approached the iliac bone. However, when the DCIA was 4 cm behind the ASIS (54 sides, 54%), it coursed posteriorly and superiorly away from the iliac spine. The vascular length of the pedicle was insufficient to transpose the vascularized iliac graft to the desired position when it was within 1 cm of the ASIS. The vascular length requirement was satisfied, and the blood supply was sufficient when the pedicle was positioned at 2 or 3 cm. Conclusion To obtain a satisfactory pedicle length and sufficient blood supply, the DCIA pedicle of the vascularized iliac graft should be placed 2 to 3 cm behind the ASIS. The dissection of DCIA has slight differences in sex and left–right position due to anatomical differences. [ABSTRACT FROM AUTHOR]

Silicon nitride (Si3N4) has great potential for applications in photoelectric and semiconductor fields. In this study, a novel strategy of fabricating Si3N4 crystals is reported, and the morphology of α-Si3N4 can be controlled. The aBN/SiO2/Si wafers were designed and irradiated by a high-energy electron beam for 2 min using home-made equipment. Tree-like α-Si3N4 dendrites and [001]-oriented unbranched α-Si3N4 whiskers can be synthesized by controlling the electron beam energy. Related formation mechanisms were analyzed based on componential and structural characterization using a scanning electron microscope and high-resolution transmission electron microscope. In addition, photoluminescence measurements indicate that the synthesized α-Si3N4 exhibit unique photoluminescence properties. This is attributed to α-Si3N4 forming abundant Si–Si bonds, Si dangling bonds, N dangling bonds and oxygen bonds in the synthesis process. These findings provide new insights into fabricating high-quality Si3N4 crystals, as well as developing related high-performance micro- or nano-devices. [ABSTRACT FROM AUTHOR]

In comparison to conventional EDM, micro EDM distinguishes itself through its brief discharge duration, narrow discharge channel radius, and concentrated energy density. However, there remains a paucity of comprehensive research on the surface formation characteristics in this domain. This paper delves into the formation mechanism of the recast layer in micro EDM workpieces, scrutinizing the primary factors that influence the formation process and the morphological attributes of the recast layer. We conducted a series of single-pulse experiments and micro EDM trials. Utilizing surface fitting tools, our experimental findings facilitated the derivation of a relational expression between the recast layer thickness of high-speed steel and the discharge parameters in micro EDM. Notably, when the energy is below 100 μJ, the recast layer thickness remains under 10 μm. Specifically, at an energy level of 16 μJ, opting for a smaller capacitance of 2200 pf and a higher voltage of 120 V in micro EDM results in a thinner recast layer. This study serves as a cornerstone for future efforts aimed at controlling and assessing the surface morphology of micro EDM. [ABSTRACT FROM AUTHOR]

How to achieve high-precision control is the core issues of the linear motor research. To solve this problem, this paper proposes a new control algorithm. on the one hand, through the sliding mode control for the unknown torque observations, in the process of observation, select a specific based function to approximate the sign function in order to eliminate the jitter of the vicinity of the switching surface; On the other hand, the use of model predictive control method (Model Predictive Control) to achieve the torque compensator track to achieve the velocity and displacement tracking. The constant sampling time of the model predictive control in the new method can effectively avoid the problems that the number of switching per unit time of the inverter can’t be expected.

In this paper, the crack phenomenon of different materials was studied according to the surface morphology of recasting layer of micro EDM workpiece. In this paper, high-speed steel and titanium alloy are used as workpiece materials, and the RC pulse power supply is used for electric discharge machining. The surface and profile of the recast layer of the workpiece are examined by scanning electron microscopy. The difference between the two in the crack phenomenon of the recast layer in micro electric spark machining is analyzed. Finally, some improvement measures are put forward to solve the problem of recasting layer crack on the surface of micro EDM workpiece.

Magnetic Cu‐BTC@Fe3O4 materials were synthesized as core‐shell nanocomposites through a secondary growth technique by the combination of magnetic Fe3O4 and Cu‐BTC, which effectively improved the thermal stability of the materials. The interaction energy of Cu‐BTC and Cu‐BTC@Fe3O4 with the xylene isomers, o‐xylene (OX), m‐xylene (MX) and p‐xylene (PX), was calculated by DFT method, which were consistent with the results of the experimental adsorption separation results. In order to study the adsorption performance of xylene isomers on Cu‐BTC@Fe3O4 composite materials, the thermodynamics and kinetics were systematically studied. The adsorption equilibrium curves were obtained by collecting the gas phase adsorption equilibrium data at different temperatures (298, 318 and 338 K) and being fitted with Langmuir and Freundlich isothermal models, respectively, in which the Langmuir isotherm equation was fitted well. Further thermodynamic calculations indicated that the affinity of xylene on Cu‐BTC@Fe3O4 is spontaneous physical adsorption combining exothermic process, while kinetic studies showed the adsorption of xylene isomers on Cu‐BTC@Fe3O4 a pseudo‐second‐order kinetic model. In breakthrough experiments, Cu‐BTC@Fe3O4 has a high adsorption capacity and selectivity (3.3 for OX/MX) at 453 K, 1.0 MPa. [ABSTRACT FROM AUTHOR]