RESUMO
Recently, ethanol has shown promising potential in the large-scale reduction of graphene oxide (GO) into graphene. However, dispersion of GO powder in ethanol is a challenge due to its poor affinity, which hinders permeation and intercalation of ethanol between GO molecule layers. In this paper, phenyl-modified colloidal silica nanospheres (PSNS) were synthesized by phenyl-tri-ethoxy-silane (PTES) and tetra-ethyl ortho-silicate (TEOS) using a sol-gel method. PSNS was then assembled onto a GO surface to form a PSNS@GO structure by possible non-covalent π-π stacking interactions between the phenyl groups and GO molecules. The surface morphology, chemical composition, and dispersion stability were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetry, Raman spectroscopy, X-ray diffractometry, nuclear magnetic resonance, and particle sedimentation test. The results showed that the as-assembled PSNS@GO suspension had excellent dispersion stability with an optimal PSNS concentration of 5 vol% PTES. With the optimized PSNS@GO, ethanol can permeate between the GO layers and intercalate along with PSNS particles via formation of hydrogen bonds between assembled PSNS on GO and ethanol, achieving a stable dispersion of GO in ethanol. The optimized PSNS@GO powder remained redispersible after drying and milling according to this interaction mechanism which is favorable for large scale reduction processes. Higher PTES concentration may result in agglomeration of PSNS and formation of wrapping structures of PSNS@GO after drying and worsen its dispersion capability.
RESUMO
Functional surfaces with superhydrophobic and superoleophobic properties are of great interest in many applications. However, such surfaces are generally difficult to obtain. Although a few superamphiphobic surfaces have been developed recently, a challenge still remains in preparing such a surface with good durability which is a critical issue in practical application. In this study, we demonstrate a facile method for preparing durable superhydrophobic and highly oleophobic surfaces using two kinds of nanoparticles. Epoxy resin is used as the adhesive material to improve the wear resistance of the surfaces. ZnO nanoparticles and SiO2 nanoparticles are used to create high surface roughness. The prepared surfaces exhibit excellent superhydrophobicity and high oleophobicity once the nanoparticles are treated with 1 H,1 H,2 H,2 H-perfluorodecyltriethoxydsilane (FAS-17). Water and ethylene glycol contact angles of the coatings can reach up to 172 ? 2? and 157 ? 2?, respectively. After undergoing strong adhesive tape peeling and mechanical abrasion, the coatings still maintain good amphiphobicity.
RESUMO
Sasanquasaponin (SQS) is an effective component of Camellia oleifera Abel. This study was designed to investigate the cardioprotective effect of SQS against ischemia-reperfusion (I/R) injury and the possible mechanism in isolated rat hearts. These hearts were pretreated by SQS only or SQS and HOE140 in different groups, and then subjected to I/R injury. Hemodynamic parameters, oxidative injury, and NO level were measured. The results showed that SQS preconditioning could decrease the incidences of arrhythmias and improve the heart functions. In addition, SQS preconditioning could protect isolated I/R injured heart against lipid peroxidation, as evidenced by increases in SOD and GSH-Px activity, and by decreases in contents of MDA, ROS generation. However, HOE140 treatment reversed all these indexes. NO production was significantly decreased after a treatment with HOE140. So we can propose that SQS preconditioning could induce the cardioprotective effects and the possible mechanism was that the activation of bradykinin-NO system by SQS preconditioning had an inhibition effect on ROS generation in isolated heart.
