Abstract: An in-vivo rapid recellularization tissue engineered blood vessel and a preparation method thereof are provided. The preparation method includes: dissolving polyglycolic acid and polyethylene glycol in an organic solvent to prepare a spinning solution, and performing electrostatic spinning according to a certain proportion to prepare a tubular polymer composite support of a special tube wall structure, the fiber on the outer side of the tube wall support containing a higher proportion of polyethylene glycol; planting seed cells on the tubular polymer support of the special tube wall structure, and under certain culture conditions, simulating body arteriopalmus flow conditions and performing perfusion culture for 3 weeks to 3 months; and removing cell components from the tube wall of the obtained engineered blood vessel by using a decellularization method to give a tissue engineered blood vessel composed of an extracellular matrix of a bionic structure.

Abstract: A power tool includes an electric motor assembly disposed at least partially in a housing and including a first electric motor, a second electric motor, and a connector, where limit values of efficiency of the electric motor assembly constitute a total efficiency interval, and efficiency values of the electric motor assembly greater than or equal to 70% constitute a first efficiency interval, where the ratio of the first efficiency interval to the total efficiency interval is greater than or equal to 0.5.

Abstract: Provided are a control method and system for water and fertilizer under drip irrigation. In the method, the crop type, soil type, fertilizer type, water-fertilizer irrigation amount and other factors are coupled with the drip irrigation tape parameters in the drip irrigation system, and matching calculation is performed to obtain the fertilization duration. In addition, deduction and calculation are performed according to the solubility of the fertilizer, the fertilization amount, the rotation irrigation area and the fertilization duration determined by the self-allocation system, and the characteristic that the maximum fertilizer absorption amount is reached when the outlet of the Venturi fertilizer applicator is at ?9 m is combined, so as to determine key components of the fertilizing machine in the drip irrigation system.

Abstract: An automatic flushing device for a screen filter of a biogas slurry drip irrigation system and a use thereof are provided. The automatic flushing device includes a feeding mechanism, a filter unit, a discharging mechanism and a control mechanism, where the filter unit is provided with a feeding end fixedly threaded to a discharging end of the feeding mechanism and a discharging end fixedly threaded to a feeding end of the discharging mechanism; and the control mechanism is clamped on a pipe of the feeding mechanism. The automatic flushing device enhances the cleaning strength and uniformity of ultrasonic waves to the filter screen. The ultrasonic vibration rod is nested inside the upper filter casing through the externally-threaded hollow cap and a threaded top portion of the upper filter casing, which greatly facilitates the cleaning, replacement and maintenance of the ultrasonic vibration rod.

Abstract: A variable-flow-rate anti-clogging emitter includes an upper casing and a lower casing, where the upper casing and the lower casing are fixedly connected with each other; the upper casing has a flat top surface provided with a water outlet and a bottom surface provided with a truncated conical slot in communication with the water outlet; the lower casing includes a flow channel portion and a discharging portion, which are recessed in an upper surface of the lower casing; the flow channel portion has one end provided with multiple parallel feeding channels and an other end communicated with the discharging portion; one end of a lower surface of the lower casing is provided with an L-shaped platform; water inlets of the multiple feeding channels are arranged on a side wall of the L-shaped platform; and an elastomer flow channel is fixedly provided between the upper casing and the lower casing.