Search

Four different material of activated carbon, i.e., coconut shell, fruit shell, wood and coal, were used to be mixed with concrete, the radon exhalation rates of concrete then was measured. At the same time, the pore distribution of activated carbon and some performances of concrete were tested. The results show that coconut shell carbon has the best effect for reduction radon exhalation rates of concrete, fruit shell carbon comes second. The adsorption mechanisms of activated carbon towards the radon gas in the solid and in the air are similar. Activated carbon have less effect on the strength of concrete, however, they have greater influence on the constructability and durability.

Researched the influence of the pore structure and water absorption on the carbonization property with sulphoaluminate foamed cement as an example. The results showed that: Under the same levels of dry density, the smaller pore size, the higher the carbonation coefficient and the integrity of pore had the same effect. After the surface water-proofing, water absorption decreased by 10% on average, the time of carbonizing completely become longer, and carbonation coefficient was increased. And put forward the methods of improving the carbonation resistance properties of sulphoaluminate cement foam materials.

This paper studies the influence of stone dust on adaptability of polycarboxylate superplasticizer and cement by the experiment of paste slump and mortar slump flow. The results indicate that polycarboxylate superplasticizer mixed in mortar increases with stone dust mixed because of large specific surface and water demand of stone dust. There is little effect on fluidity loss when the dosage of stone dust is below 18%, and it will increase significantly with the dosage more than 18%. The adaptability of polycarboxylate superplasticizer and cement will be bad when the content of stone dust in manufactured sand is over 10%. The adaptability of polycarboxylate superplasticizer and cement can be evaluated by the method of mortar slump flow.

Objective To evaluate the effects of tissue culture on the viability and development of follicles in frozen-thawed human fetal ovarian tissue before transplantation into severe combined immunodeficient (SCID) mice and to determine the optimal duration of pretransplant tissue culture. Design Experimental prospective study. Setting Animal center and reproductive laboratories in university hospitals. Intervention(s) Frozen-thawed human fetal ovarian tissue samples from 20-week-old abortuses were randomly divided into four groups and cultured in vitro for 0, 3, 6, or 9 days before being xenografted into kidney capsules of bilaterally oophorectomized severe combined immunodeficient (SCID) mice. Grafts were removed 16 weeks after transplantation. Histological analysis and assessment of proliferative cell nuclear antigen (PCNA) expression levels were used to evaluate the survival and development of follicles. Result(s) The proportion of growing follicles was significantly increased in groups cultured before transplantation as compared with the noncultured group. Sixteen weeks after transplantation, the number of follicles in the cultured grafts was higher than that in the noncultured grafts. Grafts cultured for 6 or 9 days showed higher proportions of preantral and antral follicles than grafts cultured for 0 or 3 days. PCNA immunohistochemical analysis indicated that follicle cells were in a proliferative state after culture and transplantation. Conclusion(s) The viability and development of human fetal follicles may be improved by pretransplant tissue culture. The optimal culture duration before transplantation of fetal ovarian tissue is 6 days.