Ruizhen Xu

Thermosensitive poly(N-isopropylacrylamide-co-glycidyl methacrylate) microgels for controlled drug release.

A new type of thermosensitive microgels with epoxy functional groups is designed and synthesized for drug delivery. The thermosensitive poly(N-isopropylacrylamide-co-glycidyl methacrylate) (designated as P(NIPAM-co-GMA)) microgels are prepared by an emulsifier-free emulsion polymerization method and the chemical composition of the copolymer is determined by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance ((1)H NMR). The lower critical solution temperature (LCST) of the microgels is 32°C based on the transmittance changes at 500 nm monitored by UV/visible spectrophotometry. The hydrodynamic diameter and morphology of the microgel particles are examined by dynamic light scattering (DLS) and scanning electron microscopy (SEM), respectively. The drug release properties determined using 5-FU as the drug model in vitro reveal temperature dependence and low cytotoxicity. The thermosensitive microgels have large potential as targeted anti-cancer drug carriers.

Transformation of Enhanced Glow Discharge Dynamics in Nitrogen Plasma Immersion Ion Implantation

In nitrogen enhanced glow discharge plasma immersion ion implantation, the implantation current increases sharply with the gas pressure when a threshold pressure is exceeded, indicating that the glow discharge dynamics changes with increasing diatomic gas flow rate. The voltage drop rendered by the anode glow produces noticeable N2+ dissociation and electron-atom ionization in the positive column which expands to the cathode. As a result, charged particles reach the cathode more easily, and the larger plasma density and N+/N2+ ratio in the positive column lead to the higher current. Our results clarify the implantation current characteristics and expedite adoption of this alternative plasma immersion technology.

An experimental study of magnetorheological fluids on electrical conductivity property

Magnetorheological fluids (MRFs) are smart materials made by base fluid, magnetizable particles, and stabilizer additives. A series of samples on varying of silicone oil, carbonyl iron particles, and oleic acid were prepared to investigate the stability of sedimentation and electrical conductivity property. Experimental results showed that the sample with mole ratio of oleic acid and carbonyl iron particles is two has the smallest saturation resistance, fastest response to external field, and the best stability of sedimentation. Further investigations suggested that low silicone oil viscosity and suitable amount carbonyl iron particles were desirable for enhance the electrical conductivity property of MRFs.