Defining and visualizing the three-dimensional (3D) structures of pharmaceuticals provides a new and important tool to elucidate the phenomenal behavior and underlying mechanisms of drug delivery systems. The mechanism of drug release from complex structured dosage forms, such as bilayer osmotic pump tablets, has not been investigated widely for most solid 3D structures. In this study, bilayer osmotic pump tablets undergoing dissolution, as well as after dissolution in a desiccated solid state were examined, and visualized by synchrotron radiation micro-computed tomography (SR-μCT). In situ formed 3D structures at different in vitro drug release states were characterized comprehensively. A distinct movement pattern of NaCl crystals from the push layer to the drug layer was observed, beneath the semi-permeable coating in the desiccated tablet samples. The 3D structures at different dissolution time revealed that the pushing upsurge in the bilayer osmotic pump tablet was directed via peripheral "roadways". Typically, different regions of the osmotic front, infiltration region, and dormant region were classified in the push layer during the dissolution of drug from tablet samples. According to the observed 3D microstructures, a "subterranean river model" for the drug release mechanism has been defined to explain the drug release mechanism.

Objective To discuss the application and practice of TBL teaching mode in the clinical teaching of oncology . Methods Physicians on rotational medical tour in Huadong hospital from April 2017 to August 2017 were selected as research sub-jects, and were randomly divided into 2 groups:the experimental group and the control group .Theory test and manipulation test scores were compared and analyzed between the physicians of the 2 groups.Questionnaire feedback was used to evaluate the effect of TBL teaching mode.Results Total average scores of the experimental group were 84.15 ±4.50, while those of the control group were 78.80 ±2.38, and statistically significance could be noted , when comparisons were made between the 2 groups.Results of the questionnaire survey indicated that most of the students thought that TBL teaching mode was more beneficial to comprehensive grasp of oncology knowl -edge , and TBL teaching mode was more interesting , as compared with the conventional teaching mode .More importantly , TBL teaching mode could not only improve their learning initiative , but enhance the spirit of teamwork and cooperation .Conclusion The application of TBL teaching mode in oncology clinical teaching could fully improve learning initiative of the students , strengthen the spirit of team-work, and enhance the quality of teaching .