Cement-Bonded Sub-Base Layers of Walkable and Running Structures for Rainwater Management

Sub-base layers of walkable and running road structures usually consist of a stable subsoil with sufficient load-bearing capacity under the surface layer itself in the form of concrete covers or prefabricated paving elements. Due to their load-bearing capacity, these sub-base layers are most often constructed using cement-bonded aggregate technology. The current hot topic of rainwater management brings opportunities for the construction of water-permeable structures with good water retention capacity. The retention capacity of such a structure can be ensured in ideal conditions by making this sub-base partially permeable and with an absorbent layer while maintaining its mechanical advantages. The experiment confirmed the possibility of producing cement-bonded sub-base layers using light porous aggregates based on expanded clays. The high absorption rate of the type of aggregate used is a good starting point for increasing the retention capacity of the entire system.

Polyvinyl Alcohol/Chitosan and Polyvinyl Alcohol/Ag@MOF Bilayer Hydrogel for Tissue Engineering Applications

In this paper, polyvinyl alcohol/Ag-Metal-organic framework (PVA/Ag@MOF) and polyvinyl alcohol/chitosan (PVA/CS) were used as the inner and outer layers to successfully prepare a bilayer composite hydrogel for tissue engineering scaffold. The performance of bilayer hydrogels was evaluated. The outer layer (PVA/CS) has a uniform pore size distribution, good water retention, biocompatibility and cell adhesion ability. The inner layer (PVA/Ag@MOF) has good antibacterial activity and poor biocompatibility. PVA, PVA/0.1%Ag@MOF, PVA/0.5%Ag@MOF, and PVA/1.0%Ag@MOF show anti-microbial activity in ascending order. However, its use as an inner layer avoids direct contact with cells and prevents infection. The cell viability of all samples was above 90%, indicating that the bilayer hydrogel was non-toxic to A549 cells. The bilayer hydrogel scaffold combines the advantages of the inner and outer layers. In summary, this new bilayer composite is an ideal lung scaffold for tissue engineering.

Preparation and Swelling Behaviors of High-Strength Hemicellulose-g-Polydopamine Composite Hydrogels

Hemicellulose-based composite hydrogels were successfully prepared by adding polydopamine (PDA) microspheres as reinforcing agents. The effects of PDA microsphere size, dosage, and nitrogen content in hydrogel on the mechanical and rheological properties was studied. The compressive strength of hydrogel was increased from 0.11 to 0.30 MPa. The storage modulus G’ was increased from 7.9 to 22.0 KPa. The gaps in the hemicellulose network are filled with PDA microspheres. There is also chemical cross-linking between them. These gaps increased the density of the hydrogel network structure. It also has good water retention and pH sensitivity. The maximum cumulative release rate of methylene blue was 62.82%. The results showed that the release behavior of hydrogel was pH-responsive, which was beneficial to realizing targeted and controlling drug release.