Subjects: Nuclear Science and Technology >> Nuclear Detection Technology and Nuclear Electronics submitted time 2023-12-15
Abstract： Multi-Wire gaseous detectors have been widely used in the fields of nuclear physics and nuclear technology for their advantages of radiation hardness, fast respond, large sensitive area, relative low cost, easily built and so on. The electric field calculation theories for multi-wire gaseous detector will be introduced first, and then GRFIELD, a professional gaseous detector simulation program, will be used to carry out the electric field calculations in the drift region and avalanche region together with ANSYS, which is a famous finite element analysis commercial program. Furthermore, the designed gaseous detector has also been simulated in the case of cosmic ray irradiation by a Monte Carlo program of GEANT4. The output results of current pulses, voltage pulses, and the integrated charge for each event of the detector has been achieved. And then, a multi-wire gaseous detector has been built and used to carry out the real measurements for the cosmic rays. The experiment results agree well with the previous simulations. The simulation methods and the related experiments technologies in this study will help to do design works and experiment pre-evaluations for similar gas detectors.
Subjects: Medicine, Pharmacy >> Preclinical Medicine submitted time 2017-12-27 Cooperative journals: 《南方医科大学学报》
Abstract： Objective To prepare a drug-loading film using chitosan and carboxymethyl chitosan as the carrier materials for delivering matrine to oral ulcers. Methods Matrine-loading films using chitosan or carboxymethyl chitosan as the carrier materials were prepared by solution casting method and orthogonal experiment at room temperature. The mechanical properties, surface morphology and drug-loading capacity of the drug-loading film were characterized using tensile test, scanning electron microscopy (SEM), swelling test and in vitro drug release test. Results When the molecular weight of chitosan was 650 000 and the mass ratio of chitosan/glycerol was 1∶1.4, the prepared film had the maximum mechanical strength and tensile modulus reaching 0.7875 MPa. SEM observation showed that matrine aggregated at the bottom of the drug-loading film with an asymmetrical distribution. The in vitro drug release test showed that the film had a high drug-loading capacity and a sustained drug release property. The duration of drug release from the drug-loading film was prolonged as the molecular weight of chitosan increased, reaching 23 h when the molecular weight of chitosan was 650 000. The duration of drug release was further increased to 108 h when the bottom of the drug-loading film was coated with a layer of 1% carboxymethyl chitosan. Conclusion The matrix materials of the drug-loading film are natural, green, nontoxic and biodegradable, and the preparation of the film is simple without using large quantities of organic solvents. The novel drug-loading film can obviously prolong the duration of drugs release for better local drug delivery to oral ulcers in a sustained manner.
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