Ecomaterials

 The search for non-food feedstocks is one of the main challenges in the production of biofuels. For biodiesel, research is oriented towards the use of non-conventional crops, as well as towards residues or wastes with a high content of fats and oils. Coffee grounds contain a good proportion of fats and are a commercial and domestic waste. In this work, the production of biodiesel using fats extracted from coffee grounds was evaluated in a two-step process. The fats extracted from coffee grounds with boiling to reflujo with hexane as solvent presented high acidity, 32.07 ± 0.01% (70.24 ± 0.03 mg KOH/ g fat), indicating a high content of free fatty acids (FFA). First, the fats were esterified at 60°C and 100 rpm, varying the reaction conditions. At the best conditions, 0.7% H₂SO₄ concentration, 1:6 GMR:MeOH for 120 min, the acidity decreased below 1%, with 94.92% FFA conversion to methyl esters. They were subjected to a transesterification process with KOH (1.5% m/v) in the presence of methanol (RMG:MeOH of 1:15) at 60°C and 100 rpm for 30 min. The biodiesel was separated by decantation and purified by successive washes with acidified water, which resulted in a mixture of methyl esters of linoleic (48.40%), palmitic (36.21%), stearic (8.69%) and oleic (6.69%) acids, whose properties conform to the requirements of ASTM D 6751 and EN 14214.

Currently, the most commonly used dental CAD/CAM restorative systems are ceramic materials, which can be divided into resin-ceramic composites, polycrystalline ceramics and glass ceramics according to the differences in composition. Different types of ceramics have major differences in mechanics and aesthetics and need to be selected according to clinical needs and patient demands. Each material has its own advantages and disadvantages, for example, glass ceramics are highly transparent but brittle, polycrystalline ceramics are strong but less transparent, and resin-ceramic composites combine the advantages of glass ceramics and resin materials but are less strong. In this paper, we systematically review the compositional classification, the characteristics of each type of ceramic, and recent research advances to help guide clinical selection of CAD/CAM materials.

Abstract: Objective To study the effects of three kinds of magnetic nanomaterials on reactive oxygen species, cell junction of vascular endothelial cells in vitro and their relationship. Methods Primary human umbilical vein endothelial cells (HUVECs) were randomly divided into control and magnetic nanoparticles exposed groups. Dynamic light scattering (DLS) was used to characterize the particle size and charge of nanomaterials. CCK 8 method was used to measure cell viability. Flow cytometry was used to observe the level of ROS in cells by DCFH-DA fluorescent probe labeling. Using iron staining and transmission electron microscopy (TEM) to observe the uptake