Infiltration tests were conducted in the laboratory to study water movement during infiltration in compacted clay and to determine the suction head at the wetting front as defined in the Green-Ampt infiltration equation. Tests were conducted on two clays, having low and high plasticity indices. Results of the tests show that the wetting front is diffuse and becomes increasingly so as it penetrates deeper into the soil. The wetting front is also more diffuse for molding water contents near or wet of optimum water content and for clay with higher plasticity index. Suction head at the wetting front has been found to decrease as the wetting front penetrates into the soil, with the rate of dissipation depending on the molding water content and soil type. For the clay with low plasticity index, the initial suction head at the wetting front was largest and decreased the fastest when the molding water content was near optimum. For the clay with high plasticity index, similar initial suction head and rate of dissi...

Poly (vinyl alcohol) (PVA)/reduced graphene oxide (rGO) nanocomposites is prepared by the immersion of PVA/graphene oxide (GO) nanocomposites in the reducing agent aqueous solution. The PVA/graphene nanocomposites can be used as scaffold after treatment by chemical crosslinking agents. The surface hydrophilicity of the nanocomposite scaffolds decreased with the addition of GO or rGO by measuring the contact angles of scaffolds. The electrical conductivity of PVA/rGO nanocomposite scaffold increased with rGO content increased. The highest conductivity of PVA/rGO nanocomposite scaffolds with 10 wt% rGO could reach to 12.16 × 10−3 S/m. The NIH-3T3 fibroblasts attach and grow well on the surface of PVA/rGO nanocomposite scaffolds with increasing the content of rGO. The number of cells obviously increases on the PVA/rGO nanocomposite scaffolds, especially, at 5 wt% and 10 wt% rGO. Furthermore, a good level of conductivity and a variation in the surface property of the PVA/rGO nanocomposite scaffolds have affected NIH-3T3 fibroblasts grow.

New biodegradable aliphatic PLLA-PBA-PLLA copolymers with soft poly(butylene adipate) (PBA) and hard poly(l-lactide) (PLLA) building blocks were synthesized via ring-opening polymerization (ROP). Proton nuclear magnetic resonance (¹HNMR) was utilized to confirm the volume fraction of PBA (f_PBA) within PLLA-PBA-PLLA. It was found that a PBA midblock (PBA-mid) within PLLA-PBA-PLLA-s (PLLA-PBA-PLLA triblock copolymer with a short PLLA block length) might display lamellar domain structure. However, PBA-mid within PLLA-PBA-PLLA-l (PLLA-PBA-PLLA triblock copolymer with a long PLLA block length) might locate itself as a nanoscale cylindrical domain surrounded by a PLLA continuous phase. Polymorphic crystals of PBA-mid within the PLLA-PBA-PLLA copolymers were formed after melt crystallization at the given temperatures, which were studied by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) analysis. According to the WAXD and DSC analyses, it was interesting to find that the α-type crystal of PBA-mid was favorable to develop in the lower temperature region regardless of the state (crystallization or amorphous) of the PLLA component. Additionally, when the PLLA component was held in its amorphous state, it was easier for PBA-mid within the PLLA-PBA-PLLA copolymers to transform from the metastable β-form crystal to the stable α-form crystal. Furthermore, polarized optical microscopy (POM) photos provided direct evidence of the polymorphic crystals of PBA-mid within PLLA-PBA-PLLAs.