Study of Attapulgite as an Additive in Reinforced Concrete by Substitution of Cement and Its Effects on the Durability Properties of Hardened Concrete

The valorization of Senegalese attapulgite clay in concrete, as a solution against the exhaustion of the cement deposits was studied. In that purpose, attapulgite was first calcined at 800°C to make it reactive and added in concrete by substitution of Portland cement (CEM I 52.5N) at contents of 0, 5 and 10% by conserving a constant water/cement ratio value of 0.65. The effects of the partial replacement of cement by attapulgite on the physicochemical and mechanical properties of the concrete as well as on the steel-concrete bond were examined. For this purpose, the water porosity, the intrinsic permeability and the density of the clay-based concrete were evaluated. Compression, tensile and pull-out tests were carried out to determine the impact of clay on the Young modulus, the compressive and tensile strengths and the steel-concrete bond. This study was completed by a characterization of the pozzolanic reactivity of calcined attapulgite. All the results of these studies were compared with those of Portland cement as a reference. The substitution of cement by attapulgite up to 10% in concrete has only a small influence on its porosity and permeability and confers to the concrete gain in compressive strength of 11%. However, it caused a loss of steel-concrete bond of 10%.

Effect of kidney-reinforcing,blood-activating and stasis-removing recipes on adhesion molecule expression of bone marrow mesenchymal stem cells from chronic aplastic anemia patients

OBJECTIVE： To explore the effect of kidney-rein- forcing, blood-activating and stasis-removing recipes on adhesion molecule expression of bone mar- row mesenchymal stem cells （MSCs） from patients with chronic aplastic anemia （CAA）. METHODS： We used three Traditional Chinese Medicine recipes, namely a kidney-reinforcing recipe （KRR）, blood-activating and stasis-removing recipe （BASRR）, and kidney-reinforcing, blood-activating and stasis-removing recipe （KRBASFIR）, and a nor- mal saline control to prepare herbal medicine se- rum in Sprague Dawley rats. Thirty CAA patients were enrolled in the experimental group, including 17 kidney-Yang deficient patients and 13 kidney-Yin deficient patients. Ten healthy individuals were included in the control group. MSCs were isolated from bone marrow samples, and the cell density was observed to measure their proliferation ability by microscopy on days 2, 7, and 14 after isolation. In addition, the expression of adhesion molecules of bone marrow MSCs （CD106, CD49d, CD31 and CD44） were detected by flow cytometry after 48 h of treatment with the four different herbal medi- cine serums. RESULTS： The proliferation of MSCs from kid- ney-Yang deficient and kidney-Yin deficient pa- tients was weaker than that of MSCs from the con- trol group. The expression of all adhesion mole- cules of bone marrow MSCs from CAA patients was obviously lower than that in the control group （P〈 0.01）. The expression of CD49d and CD31 in MSCs from patients with a kidney-Yin deficiency was low- er than in those with a kidney-yang deficiency （P〈 0.05 and P〈O.01, respectively）. For kidney-Yang defi- cient patients, CD31 expression in the KRBASRR group was significantly higher than that in the BASRR group （P〈O.01）, while CD44 in the KRBASRR group was significantly higher than that in both KRR and BASRR groups （P〈O.01）. For kidney-Yin defi- cient patients, CD106 and CD49d expression in the KRBASRR group was obviously higher than that in the KRR group （P〈0.05）, while CD31 and CD44 ex- pression in the KRBASRR group was significantly higher than that in both KRR and BASRR groups （P〈 0.05 and P〈0.01, respectively）. CONCLUSION： The bone marrow microenviron- ment in CAA patients is abnormal. The effect of KRBASRR may be better than that of KRR and BASRR for kidney-Yang deficient and kidney-Yin de- ficient patients by improving the expression levels of MSC adhesion molecules.