Porous Ti-Mg composites were successfully fabricated through powder metallurgy processing with ammonium hydrogen carbonate （NH4HCO3） as a space-holder. The effects of NH4HCO3 on properties of porous composites were comprehensively investigated. The pore characteristics and compressive properties of the specimens were characterized by X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. The results show that the porosity of the porous composites can be tailored effectively by changing the amount of NH4HCO3 added, and the use of NI-I4HCO3 has no influence on the microstructure and phase constituents of the Ti-10%Mg porous composites. The open porosity and compressive strength as well as compressive elastic modulus vary with the adding amount and particle size of NHaHCO3. When the mass fraction of NHaHCO3 added is 25%, elastic modulus and compressive strength of composites with porosity of around 50% are found to be similar to those of human bone.
The effect of inhaled nano-TiO2 on lung histology and serum biochemical indexes is evaluated in healthy and adult Kunming mice（eight in each group）after exposure to TiO2 aerosols（1 500 mg/m3）in a sealed chamber.Another eight mice are exposed to indoor air to be served as a control group.Lung tissue and blood are collected after euthanizing the animals.The results show that lactate dehydrogenase（LDH）activity increases in all experimental groups.Alanine aminotransferase（ALT）activity and blood urea nitrogen（BUN）levels are increased in the group exposed to TiO2 aerosols for 28 d,and creatinine（Cr）levels are increased in 14 d and 28 d samples（P0.05）.No obvious changes are observed in other serum indexes.Lungs of mice exposed to 28 d exposure show significant but moderate increase in pulmonary inflammation,and many TiO2 particles are found in the interstitium of pulmonary alveoli.
