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Objective To observe the promotional effect of exosomes (MenSC-Exos) isolated from menstrual bloodderived mesenchymal stem cells (MenSCs) on the healing of skin wounds in SD rats and to investigate the mechanism. Methods MenSCs from healthy adult female volunteers were isolated and cultured, and MenSC-Exos were extracted. SD rats were randomly divided into the experimental and control groups, and mechanical wounds of the dorsal skin were made and treated with MenSC-Exos or PBS, respectively. We observed the wound healing and calculated the wound healing rate, used HE staining to observe the infiltration of inflammatory cells on the wound, used immunofluorescence to detect M1 and M2 macrophages, used immunohistochemistry to detect IL-6, IL-10, neovasculature, collagen type I, collagen type III in the tissues of the wound, and used Masson staining to detect the content and maturity of collagen on the wound. Fibroblasts were cultured and divided into the exosome and PBS groups, during which MenSC-Exos or PBS were added, respectively, and cell proliferation ability was detected by CCK-8 assay and cell migration ability by Scratch assay. Results The wound healing rate, type III collagen deposition rate, and collagen content of the experimental group were higher than those of the control group on postoperative day 7 and 14, and the type I collagen deposition rate was lower than that of the control group (all P<0. 05). The number of inflammatory cells and the M1/M2 ratio of the trauma on postoperative day 7 were lower in the experimental group than in the control group, and the number of M2-type macrophages was higher than that in the con‐ trol group (all P<0. 05). Compared with the control group, the experimental group had lower IL-6 expression and higher IL10 expression and vascular endothelial cell expression on the 3rd and 7th postoperative days of the trauma (all P<0. 05). The cell proliferation ability of the exosome group was higher than that of the PBS group from 1 to 5 days of culture, and the cell migration rate of the exosome group was higher than that of the PBS group at 24 h of culture (all P<0. 05). Conclusion MenSC-Exos can promote the healing of rat skin wounds, and the mechanism may be related to the regulation of inflammatory response, promotion of angiogenesis and fibroblast proliferation, and regulation of collagen remodeling. [ABSTRACT FROM AUTHOR]

In order to better participate in the Arctic environmental governance and enhance the status in the environmental governance system, the indigenous peoples in Arctic area are committed to emphasizing the value of the indigenous knowledge through knowledge supply, so as to obtain intellectual power. The indigenous knowledge supply is based on the organizational basis including indigenous organizations, the Arctic Council and relevant research institutions, as well as the institutional basis of the "Ottawa Traditional Knowledge Principles". Indigenous knowledge plays an important role in providing raw data, improving the knowledge system, building regional consensus and helping the indigenous self-determination process. However, due to factors such as the Arctic environmental governance mechanism, the stability of the Arctic region, the fragmentation of the relationship between indigenous knowledge supply and Arctic environmental policy formulation, and the differences in values and research methods between indigenous peoples and the Western world, the process of knowledge supply for Arctic indigenous peoples is relatively slow. Knowledge collaborative production under the guidance of indigenous knowledge holders can break through the limitations of indigenous knowledge supply and is an effective way to improve indigenous knowledge supply. [ABSTRACT FROM AUTHOR]

In this paper, modified cementitious powders with different doping amounts of calcium carbide slag (0,0.5 wt%,1.0 wt% and 1.5 wt%) were prepared with 32.5 grade ordinary portland cement, II grade fly ash and mirabilite as raw materials and industrial waste calcium carbide slag as additive materials. The effects of calcium carbide slag doping on the crystal structure, micro morphology, mechanical properties, setting time and combined water content of modified cementitious powder were analyzed.The results show that the doping of carbide slag doesn’t produce new products, but accelerates the consumption of C2S and C3S and improves the rate of hydration reaction.When the doping amount of carbide slag is 1.0 wt%, the hydration products are most closely combined.With the increase of calcium carbide slag doping, the setting time of the modified cementitious powder gradually decreases, and the compressive strength and chemical binding water content at 28 d first increase and then decrease.When the doping amount of carbide slag is 1.0 wt%, the compressive strength and chemical binding water content at 28 d reach the maximum, which are 2.98 MPa and 6.8% respectively.This is because the addition of appropriate amount of calcium carbide slag accelerates the hydration reaction of cementitious powder, increases its structural compactness, and improves the mechanical properties of cementitious powder.It can be seen that the optimum doping amount of carbide slag is 1.0 wt%. [ABSTRACT FROM AUTHOR]

In view of the problems of poor low-speed performance of the variable - capacitance linear electro static motor under the sine wave - based driving method and the complicated design of the large-scale converter, a driving method based on the square wave is proposed. The stator electrodes are divided into A phase electrodes, B-phase electrodes, and C phase electrodes. Each phase electrode is connected to a square wave drive signal with a magnitude of 1 kV at different timings. The electrostatic force caused by the potential difference between the stator and the mover is used as the driving force of the motor. In order to obtain a compact and efficient power supply and a three-phase square wave with an amplitude of 1 kV, a DC-DC adjustable DC power supply based on a push - pull topology and a drive circuit based on a half bridge are designed. The feasibility of this method is proved by simulation and experiments. At low speeds, the drive waveforms at both ends of the motor are smooth, and the motor can move forward, forward and reverse smoothly. Simulation experiments show that at low speeds, the drive waveforms at both ends of the motor are smooth, and the motor can move forward, forward and reverse smoothly, indicating the feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

A series of SiC porous ceramic powders with different sintering temperature (1 600,1 630,1 660 and 1 690 ℃) are prepared by reactive sintering process. The phase structure, microstructure, porosity and mechanical properties of SiC porous ceramics are characterized by XRD, SEM, porosity test, compressive strength test and oil-water separation test. The results show that the characteristic diffraction peak intensity of SiO2 increases with the increase of sintering temperature, and the characteristic diffraction peak intensity of SiO2 is the highest at 1 690 ℃. With the increase of temperature, the porosity of SiC porous ceramics first decreases and then increases, and the lowest porosity is 32.1% at 1 660 ℃. SEM analysis shows that the SiC porous ceramics sintered at 1 600 and 1 630 ℃ contain more small particles, and the particles are dispersed. With the increase of sintering temperature, the small particles decrease gradually, and the SiC porous ceramics shrink and grow up gradually. The analysis of mechanical properties shows that the compressive strength of porous SiC ceramics increases firstly and then decreases slightly with the increase of sintering temperature, and the maximum compressive strength is 25.6 MPa at 1 660 ℃. The oil-water separation test shows that with the increase of sintering temperature, the membrane flux of SiC ceramics decreases first and then increases slightly, and the rejection rate increases first and then decreases slightly. When the sintering temperature is 1 660 ℃, the membrane flux is 553.8 L/(m²·h) and the rejection is 91.5%. [ABSTRACT FROM AUTHOR]