Abstract: A method and a sensor for detecting L-cystine are disclosed. The method is implemented by assembling a sodium 3,3?-dithiodipropane sulfonate (SPS) membrane on a surface of Au membrane layer of an Au electrode and using an extended gate of field effect transistor (FET) and in-situ signal amplification of the FET to detect L-cystine sensitively. The polyanion of the SPS membrane adsorbs and binds a positively charged target L-cystine through electrostatic interaction, thus forming an electric double layer structure to generate a membrane potential identifying a monovalent organic ammonium ion. The sensor includes the FET, wherein a gate-extended gold electrode is arranged on the FET, and the SPS membrane is assembled on the surface of the Au membrane layer of the gate-extended gold electrode. The sensor has an excellent Nernst response to L-cystine.

Abstract: The invention discloses a center lock structure, comprises a chassis, rotary sliding sleeve and a center rod, the top of the rotary sliding sleeve is circumferentially and slidely connected with the chassis; and the center rod is extended into the rotary sliding sleeve along the top of the chassis, an elastic member is provided at one side on the bottom of the center rod, the elastic member is exposed outside the center rod when there is no external force, and the elastic member is concealed in the center rod when squeezed by an external force; in the invention, by the center rod, upper and lower rotary sliding sleeve, through holes and the accommodating grooves for pressing or releasing the elastic member, the structure can be unlocked by rotation and pull-down.

Abstract: A sand storage and conveying apparatus is provided. The sand storage and conveying apparatus includes: a sand storage device, at least two first conveying devices and a lifting device. The sand storage device includes at least two sand storage tanks arranged along a first direction; the at least two first conveying devices are arranged along the first direction and configured to convey sand to the at least two sand storage tanks, respectively; the lifting device includes a supporting frame and at least two lifting members connected onto the supporting frame, the at least two lifting members are arranged along the first direction, and each of the at least two lifting members is configured to lift a container with sand and put the container with sand into at least one of the first conveying devices.