Abstract: A biosensing platform for in-situ sampling and target detection based on upconversion luminescence, including: an upconversion luminescent paper-based microfluidic device, an upconversion luminescent biosensor, and a portable detection device based on smartphone imaging. The upconversion luminescent paper-based microfluidic device is configured to sample a to-be-detected substance in situ. The upconversion luminescent biosensor is configured to allow a target to specifically recognize the to-be-detected substance. The portable detection device is configured to detect a content of the to-be-detected substance. The upconversion luminescent biosensor is prepared as follows. (S1) An upconversion nanoparticle seed is prepared. (S2) Core-shell upconversion nanoparticles are prepared. (S3) Core-shell-shell upconversion nanoparticles (UCNPs) are prepared. (S4) The UCNPs is subjected to hydrophilic modification. (S5) The hydrophilically-modified UCNPs are modified with DNA.

Abstract: An X-ray tube includes a target and a cathode assembly. The cathode assembly includes a first filament configured to emit a first beam of electrons toward the target, a first gridding electrode coupled to the first filament, a second filament configured to emit a second beam of electrons toward the target, and a second gridding electrode coupled to the second filament.

Abstract: In one embodiment, an X-ray tube is provided. The X-ray tube comprises at least one thermionic cathode configured to generate an electron beam, a target assembly configured to generate X-rays when impinged with the electron beam emitted from the thermionic cathode, a high voltage supply unit for establishing an output voltage across the thermionic cathode and the target assembly for establishing an accelerating electric field between the thermionic cathode and the target assembly and a mesh grid disposed between the thermionic cathode and the target assembly, the mesh grid configured to operate at a voltage so as to lower the electric field applied at the surface of the thermionic cathode. Further, the voltage at the mesh grid is negatively biased with respect to the voltage at the thermionic cathode.

Abstract: An X-ray tube includes a target and a cathode assembly. The cathode assembly includes a first filament configured to emit a first beam of electrons toward the target, a first gridding electrode coupled to the first filament, a second filament configured to emit a second beam of electrons toward the target, and a second gridding electrode coupled to the second filament.

Abstract: In one embodiment, an X-ray tube is provided. The X-ray tube comprises at least one thermionic cathode configured to generate an electron beam, a target assembly configured to generate X-rays when impinged with the electron beam emitted from the thermionic cathode, a high voltage supply unit for establishing an output voltage across the thermionic cathode and the target assembly for establishing an accelerating electric field between the thermionic cathode and the target assembly and a mesh grid disposed between the thermionic cathode and the target assembly, the mesh grid configured to operate at a voltage so as to lower the electric field applied at the surface of the thermionic cathode. Further, the voltage at the mesh grid is negatively biased with respect to the voltage at the thermionic cathode.

Abstract: A cathode cup is provided. The cathode cup includes one or more pockets; and one or more filaments associated with the one or more pockets. A same number of pockets as filaments are present. Each pocket is associated with exactly one filament and is configured to have a length that is tailored to a length of the filament. The cathode cup can be used in an X-ray system having an anode and a cathode. A method of electron beam shaping is provided. The method includes the following steps. A computer-simulated model of a cathode cup is created. The model is used to predict focal spot dimensions. The predicted focal spot dimensions are compared to desired focal spot dimensions. The steps of creating, using and comparing are repeated until the predicted focal spot dimensions match the desired focal spot dimensions. A cathode cup is created based on the computer-simulated model.

Abstract: A cathode cup is provided. The cathode cup includes one or more pockets; and one or more filaments associated with the one or more pockets. A same number of pockets as filaments are present. Each pocket is associated with exactly one filament and is configured to have a length that is tailored to a length of the filament. The cathode cup can be used in an X-ray system having an anode and a cathode. A method of electron beam shaping is provided. The method includes the following steps. A computer-simulated model of a cathode cup is created. The model is used to predict focal spot dimensions. The predicted focal spot dimensions are compared to desired focal spot dimensions. The steps of creating, using and comparing are repeated until the predicted focal spot dimensions match the desired focal spot dimensions. A cathode cup is created based on the computer-simulated model.