Effect of Crushed Glass Cullet Sizes on Physical and Mechanical Properties of Red Clay Bricks

This study reports the effect of clear waste glass from bottles added on 20 to 30 wt.% and variable particle size (<500, <300, and <212 μm), into clay mixtures for the handmade brick manufacturing process. The bricks were manufactured with mixtures of clay, crushed glass, and water in different proportions, homogenized, casted in wooden molds, air-dried at room temperature for 72 h, and sintered at 1000°C for 12 h. Total shrinkage, water absorption, compressive strength, microstructure, and phase composition are discussed with respect to glass content and its particle size. The results indicate that increasing the content of glass and decreasing its particle size enhanced significantly the brick properties of water absorption and compressive strength by up to 18.5% and 6.8 MPa, for bricks with 30 wt% and particle size lower than 212 μm. It is proposed that decreasing the glass particle size its surface area increases allowing easier melting of glass by lower energy consumption, reducing porosity and enhancing brick properties

Antimicrobial Properties of Biofunctionalized Silver Nanoparticles on Clinical Isolates of Streptococcus mutans and Its Serotypes

(1) Background: Streptococcus mutans (S. mutans) is the principal pathogen involved in the formation of dental caries. Other systemic diseases have also been associated with specific S. mutans serotypes (c, e, f, and k). Silver nanoparticles (SNP) have been demonstrated to have good antibacterial effects against S. mutans; therefore, limited studies have evaluated the antimicrobial activity of biofunctionalized SNP on S. mutans serotypes. The purpose of this work was to prepare and characterize coated SNP using two different organic components and to evaluate the antimicrobial activity of SNP in clinical isolates of S. mutans strains and serotypes; (2) Methods: SNP with bovine serum albumin (BSA) or chitosan (CS) coatings were prepared and the physical, chemical and microbiological properties of SNP were evaluated; (3) Results: Both types of coated SNP showed antimicrobial activity against S. mutans bacteria and serotypes. Better inhibition was associated with smaller particles and BSA coatings; however, no significant differences were found between the different serotypes, indicating a similar sensitivity to the coated SNP; (4) Conclusion: This study concludes that BSA and CS coated SNP had good antimicrobial activity against S. mutans strains and the four serotypes, and this study suggest the widespread use of SNP as an antimicrobial agent for the inhibition of S. mutans bacteria