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Due to the complicated working conditions of the ship stern-shaft mechanical seals, it is very difficult to evaluate and optimize the temperature on the sealed end faces. In the paper, one FEA model of the small taper convergent stern-shaft mechanical seals was put forward, and the nonlinear end-face liquid film pressure distribution was derived from different end-face gaps based on the simplified Reynolds equation as the end-face input parameters in FEA model. To prove the correction of the FEA results, one experiment was designed and completed. At the same time, combined with a parametrically coupled FEA model and an orthogonal experimental design, one PSO-BP-GA method based on the combination of particle swarm optimization (PSO), BP neural network and genetic algorithm (GA) was proposed to optimize the temperature of the sealed end faces. The results show that aiming at the prediction accuracy of the temperature on the sealed end faces, the PSO-BP algorithm is higher than BP algorithm and GA-BP algorithm, which error interval is shortened about 40% and 29%, respectively. Subsequently, PSO-BP-GA algorithm is obviously better than BP-GA algorithm and GA-BP-GA algorithm, which validates its effectiveness and feasibility. It will help to lay a theoretical foundation for temperature evaluation on the sealed end faces.

Comprehensive Summary: Kasha's exciton model proposes that T1 energy levels of organic compounds are insensitive to molecular aggregation and microenvironment change because of negligible small transition dipole moments of T1 states. This model holds true in most organic systems till now. Here we report the fabrication of twisted organic phosphors with intramolecular charge transfer characters and flexible molecular structures. When doped into different organic matrices, the twisted phosphor adopts different conformation, exhibits distinct phosphorescence colors and T1 energy levels, which violates Kasha's exciton model in organic system. Given that the change of phosphorescence colors and maxima can be readily distinguished by human eyes and conventional instrument, the twisted phosphors would be exploited as a new type of molecular probe, which would exhibit potential application in optical sensing and stimuli‐responsive systems. [ABSTRACT FROM AUTHOR]

BACKGROUND: Polysaccharide hydrogel is one of the most important materials for the colon target drug release system. However, the degradation time of polysaccharide hydrogel is much longer than the retention time in the colon. The drugs are expelled from the body before being released. OBJECTIVE: In order to match the degradation of drug carriers and their retention time in the colon, a rapidly degradable konjac glucomannan (KGM) hydrogel was designed for colon target drug release. METHODS: A crosslinker containing azo bond, olsalazine, was used to prepare the rapidly degradable KGM hydrogel. The degradation and drug release of the hydrogels with different crosslinking densities in the normal buffer and the human fecal medium were studied to evaluate the efficiency of colon drug release. RESULTS: More than 50% of the KGM hydrogel by weight was degraded and more than 60% of the 5-fluorouracil (5-Fu) was released within 48 h in 5% w/v human fecal medium. CONCLUSION: The drug was released more rapidly in a simulated colon environment than in a normal buffer. Furthermore, the drug release was controlled by the degradation of the hydrogel. The KGM hydrogel containing azo crosslinker has great potential for colon drug release. [ABSTRACT FROM AUTHOR]

Abstract Polpyrrole (PPy)/Ag nanocomposites were successfully synthesized at the interface of water and ionic liquid by one-step UV-induced polymerization. Highly dispersed PPy/Ag nanoparticles were obtained by controlling the experimental conditions. The results of Fourier-transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy revealed that the UV-induced interface polymerization leaded to the formation of PPy incorporating silver nanoparticles. It was also found that the electrical conductivity of PPy/Ag nanocomposite was about 100 times higher than that of pure PPy.