The diversity of species is striking, but can be far exceeded by the chemical diversity of compounds collected, produced or used by them. Here, we relate the specificity of plant-consumer interactions to chemical diversity applying a comparative network analysis to both levels. Chemical diversity was explored for interactions between tropical stingless bees and plant resins, which bees collect ...

introduction: in orthodontic therapy ,different materials are used and their presence in oral cavity may modify their properties. the purpose of this study was to evaluate the direct and indirect biocompatibility of three orthodontic composite resins on culture of human oral fibroblasts. methods: this was an interventional experimental study. the biocompatibility of three orthodontic composite ...

In the earlier study about polymer network of phenolic and epoxies resins mixed with linseed oil, only Phencat 15 was used as the catalyst for the phenolic resin. In this study, Phencat 382 and UH (a urea hydrochloride solution based on a 1 : 1 mole ratio of urea : hydrochloric acid 32%) will be used as catalysts to study their effects on the polymer network of phenolic and epoxy resins mixed w...

Low mole ratio urea-melamine-formaldehyde (UMF) resins synthesized with 2.5% and 5.0% melamine levels added at the beginning, middle, and end points of the first alkaline step of the typical urea-formaldehyde (UF) resin synthesis procedure were compared with typical UMF resins synthesized with melamine additions made at the final alkaline step. Various resin analysis, particleboard preparation,...

Objective The aim of the present study was to evaluate the mechanical and thermal characteristics of two denture base acrylic resins containing silver nanoparticles (AgNPs). Material and Methods Two different acrylic denture base resins (heat-polymerized and microwave polymerized) containing 0.3, 0.8 and 1.6 wt% AgNPs were evaluated for flexural strength, elastic modulus and impact strength. ...

background: the purpose of this in vitro study was to evaluate surface discoloration of three microhybrid composite resins (esthet•x hd, clearfi l ap-x, gradia direct) and fi ve nanohybrid composite resins (ceram•x, gc kalore, g-aenial, grandio, grandioso), after staining and bleaching procedures. materials and methods: the composite resins were polymerized with a curing light (celalux ii, voco...

The color of 7 composite resins, an unfilled restorative resin, and 3 glaze coatings was determined by reflection spectrophotometry and visually with Munsell color tabs. Statistically significant correlations existed between comparable parameters of the spectrophotometric and Munsell data. There was observable color variations among the 11 resins studied, but only 3 materials were within the ra...

The acid-etch technique for bonding composite resins to enamel has revolutionized the practice of pediatric restorative dentistry. Although bonding resins to dentin has proved to be a difficult challenge, ongoing advances have improved the reliability and predictability of dentinal adhesion. The purpose of this paper is to review the subject of dentin bonding; its development, current status, a...