Preparation and characterization of fast dissolving pullulan films containing griseofulvin nanoparticles for bioavailability enhancement

The aim of this study is to enhance the bioavailability of griseofulvin, a model poorly water-soluble drug, via increasing drug dissolution rate through preparation of drug nanoparticle-laden, pullulan-based strip films. The work entails (i) wet-milling griseofulvin in a stirred media mill using pullulan (polymer) along with sodium dodecyl sulfate (surfactant) as stabilizers, (i i) preparing strip films by casting-drying a precursor suspension consisting of the mixture of the milled drug suspension and a film-forming pul l ul an–xanthan gum-glycerin solution, (iii) characterizing the suspensions and the films, and (iv) exploring the effects of film thickness, drug and xanthan gum loadings, and drug particle size on the drug content uniformity, mechanical properties, and in vitro drug release from the films. Results show that thin strip films exhibited excellent content uniformity, fast drug release without having excessive amount of toxic surfactants, and easy modulation of the properties, which demonstrates their effectiveness and versatility

Research of the FLC + PID switching control strategy based on real-time error for the pneumatic polishing force regulating system

This paper designs an active pneumatic polishing force control system and investigates its control strategy. A straightforward method based on the experiments is proposed for identifying and modeling the pneumatic system and a convenient and effective control strategy based on real-time error is proposed for pneumatic polishing force regulating. Corresponding function between the input duty cycles and the output force values is created based on the experiment data tested by the system. Then the pneumatic force regulating system is modeled by the corresponding function. Base on the results of simulations and experiments, a FLC (Fuzzy Logic Control) + PID (Proportion-Integration-Differentiation) switching control strategy is designed with a switching mechanism to choose different control algorithm based on real-time error which can take the advantages of both PID and FLC. The FLC + PID switching controller can eliminate the steady state errors occurring in FLC controller and achieve the same accuracy as the PID controller but with a faster response speed. The approach effectively stabilizes the polishing force, resulting in polishing force errors that are distributed within ± 1 N. The mean errors are less than 0.2 N and the absolute mean errors hover around 0.3 N. The pneumatic polishing force control system regulated by the FLC + PID switching control exhibits effectiveness, stability, high control precision and fast response speed, and satisfies the force control requirements of polishing process

Process parameter analysis of ultrasonic vibration-assisted polishing of SiCp/Al ceramics based on optimized Hilbert trajectories

As an important ceramic matrix composite material, SiCp/Al ceramics have found extensive applications across several domains. However, the intricate nature of their material properties has resulted in a scarcity of scholarly investigations pertaining to the topic of ultrasonic vibration-assisted polishing (UVAP) of SiCp/Al ceramics. To solve this problem, a theoretical derivation of the material removal model (MRM) for UVAP SiCp/Al ceramics is presented in this paper. The selection of UVAP feeding speed is analyzed and discussed. The process parameters of UVAP of SiCp/Al ceramics are optimized based on the improved Hilbert's trajectory characteristics. According to the experimental results, high-quality machined surfaces can be obtained and the “fish scale” phenomenon can be avoided when the feeding speed is 0.015 m/s. Compared with the traditional trajectory, the improved Hilbert trajectory is easier to achieve uniform surface polishing. The introduction of ultrasonic amplitude (UA) can increase the material removal rate (MRR) by more than 21.6 % compared with the conventional polishing method. The maximum removal depth (MRD) increased by more than 27.76 % and the surface roughness (SR) is reduced by more than 76.45 %. The research results have an important application value for realizing efficient and high-quality polishing of SiCp/Al ceramics