An Insight in to Various Metallic Oxide Nanoparticles as Antimicrobials and Their Applications in Dentistry

Oral cavity contains numerous microorganisms. Among them, some are pathogenic and cause infections. Hence to control and prevent such infections, a lot of research has been conducted on different materials using various advanced techniques. Nanotechnology and nanoscience have emerged in the recent years exploring the antimicrobial effects of metal nanoparticles. Metal oxide nanoparticles have shown good results against microorganisms. Distinct physical, chemical and biologic properties of metallic oxide nanoparticles make them efficient antimicrobial agents. Both the size and high surface to volume ratio have been considered as the reason for their microbicidal efficacy. Metallic oxide nanoparticles show high durability and less cell toxicity compared to organic nanoparticles. And this positive response of metallic oxide nanoparticles make their use in medical and dental fields more promising. Most of the infections of oral cavity are fungal, bacterial or viral. In dentistry, microorganisms are believed to cause failures of many treatment by causing infections. To achieve a long-term success of treatment rendered, various possibilities have been studied. Application of this nanotechnology in dentistry termed as nano dentistry, has brought many effective changes in the control of oral infections as well as changes in the dental materials. Various metallic nanoparticles like silver nanoparticles, zinc oxide nanoparticles etc., have been used as well as modified in order to apply in dentistry. Many researches have been carried out by incorporating metallic oxide nanoparticles with dental materials which have shown excellent antimicrobial effectiveness. This review focuses on metal and metallic oxide nanoparticles and their effectiveness as antimicrobials and their various applications in dental field. KEY WORDS Nanoparticles, Antimicrobials, Metallic Oxides, Dental Materials, Dentistry

Influence of Metallic Oxide Nanoparticles on the Mechanical Properties of an A-TIG Welded 304L Austenitic Stainless Steel

Austenitic stainless steels represent a significant aerospace material, being used for various castings, structural components, landing gear components, afterburners, exhaust components, engine parts, and fuel tanks. The most common joining process is tungsten inert gas (TIG) welding, which possesses many advantages such as suitability to weld a wide range of ferrous and non-ferrous metals and alloys, providing high quality welds with good mechanical properties. Its major disadvantage is low productivity due to low penetration and welding speed. This can be overcome by introducing an activating flux before welding. The activating flux reverses the material flow of the weld pool, significantly increasing penetration. Therefore, shielding gas consumption is reduced and welding without a consumable is enabled. However, the consumable in conventional TIG also enables the conditioning of the mechanical properties of welds. In this study, Si and Ti metallic oxide nanoparticles were used to increase the weld penetration depth, while bend testing, tensile, and impact toughness were determined to evaluate the mechanical properties of welds. Furthermore, optical emission spectroscopy, light, and scanning electron microscope were used to determine the chemical compositions and microstructures of the welds. Chemical compositions and weld mechanical properties were similar in all specimens. The highest tensile and impact properties were obtained with the specimen welded with the flux containing 20% TiO2 and 80% SiO2 nanoparticles. Although lower than those of the base metal, they were well within the nominal base metal mechanical properties.

Ethylene mediates CuO NP-induced ultrastructural changes and oxidative stress in Arabidopsis thaliana leaves

Metallic oxide nanoparticles (NPs) have received great importance due to their unique properties and valuable applications in various fields.