Abstract: Provided is a focusing assembly including a focusing barrel and a barrel retaining ring; the focusing barrel includes a first sleeve, a second sleeve, and a third sleeve that are sequentially sleeved from inside to outside of the focusing barrel; the first sleeve is provided with a lens mounting portion for mounting a focusing lens, a first end of the second sleeve is provided with a display screen mounting portion for mounting a display screen, a second end of the second sleeve is detachably connected to the barrel retaining ring, the first end and the second end being opposite ends of the second sleeve; and the lens mounting portion and the display screen mounting portion are configured such that the relative position thereof in a focusing direction of the focusing assembly is adjustable.

Abstract: A structure, a method, and an electronic device for multi-coil handheld magnetic particle imaging (MPI) are provided. The structure for multi-coil handheld MPI includes a processing device, a control device, an imager, a gradient and scanning module, an excitation and correction module, and a detection module, where the gradient and scanning module includes a first circular coil pair and a second circular coil pair; the excitation and correction module includes a circular excitation and correction coil; and the detection module includes a circular detection coil. The structure for multi-coil handheld MPI focuses the imaging region in a specific part, improving the MPI accuracy, and features small volume, simple structure, and low power consumption.

Abstract: A handheld MPI system and method based on field free line (FFL) rotation is provided. The handheld MPI system includes: a gradient module configured to construct a gradient field with an FFL; a cooling module configured to cool the gradient module; an excitation module configured to excite magnetic particles in a region of the FFL; a detection module configured to receive an excitation response signal of the magnetic particles and counteract an excitation signal directly induced by a reception coil; a rotation module configured to control the gradient module and the cooling module to rotate around an axis of an excitation coil; a control and signal processing module configured to control each module to operate as needed, and process a received magnetic particle induction signal; and an image reconstruction module configured to reconstruct a magnetic particle distribution into a two-dimensional image.

Abstract: A method of producing a film of carbon nitride material, including the steps of providing a precursor of the carbon nitride material in a reacting vessel and a substrate substantially above the precursor of the carbon nitride material; heating the reacting vessel, the precursor of the carbon nitride material and the substrate at the first predetermined temperature; and quenching the reacting vessel to reach the second predetermined temperature; wherein the film of carbon nitride material is formed on a surface of the substrate during the quenching of the reacting vessel.

Abstract: A method of producing a film of carbon nitride material, including the steps of providing a precursor of the carbon nitride material in a reacting vessel and a substrate substantially above the precursor of the carbon nitride material; heating the reacting vessel, the precursor of the carbon nitride material and the substrate at the first predetermined temperature; and quenching the reacting vessel to reach the second predetermined temperature; wherein the film of carbon nitride material is formed on a surface of the substrate during the quenching of the reacting vessel.