Effect of Squeeze Casting on Microstructure and Mechanical Properties of Hypereutectic Al-xSi Alloys

The effect of squeeze casting on microstructure and mechanical properties of hypereutectic Al-xS i alloys（x = 15, 17.5, 22 wt%） was investigated in this study. Results show that microstructure of the hypereutectic Al-x Si alloys was obviously improved by squeeze casting. The amount of coarse primary Si phase decreased, while that of fine primary α-Al dendrites increased with the increase of squeeze casting pressure. Due to the decrease of coarse primary Si particles, cracking of the matrix was reduced, whilst the fine microstructure, and mechanical properties of the squeeze casting alloys were improved. Compared with gravity casting alloys, mechanical properties of the hypereutectic Al-xS i alloys solidified at 600 MPa were improved significantly. Hardness of the squeeze casting hypereutectic Al-（15, 17.5, 22 wt%） Si alloys was improved by 15.91%, 12.23%, 17.48%, ultimate tensile strength was improved by 37.85%, 32.27%, 22.74%,and elongation was improved by 55.83%, 167.86%, 126.76%, respectively. Due to the uniform distribution of Si phases in squeeze casting Al-x Si alloys, their wear resistance was markedly enhanced.

A new Eu-MOF for ratiometrically fluorescent detection toward quinolone antibiotics and selective detection toward tetracycline antibiotics

Development of new self-calibrating fluorescent sensing methods has been a popular research field with the aim of protecting the human health and environment sustainability. In this work, a novel Eu-based metal organic framework(MOF) Eu(2,6-NDC)(COO)(BUC-88) was developed by employing 2,6-NDC(2,6-naphthalenedicarboxylic acid) as bridging ligands. BUC-88 performed different sensing process toward quinolone antibiotics and tetracyclines antibiotics in terms of fluorescence intensity and color. BUC-88exhibited excellent selectivity and sensitivity detection property toward enrofloxacin(ENR), norfloxacin(NOR) and ciprofloxacin(CIP) over other Pharmaceutical and Personal Care Products(PPCPs), accomplishing the detection limit of 0.12 μmol/L, 0.52 μmol/L, 0.75 μmol/L, respectively. Notably, BUC-88 acted as an excellent fluorescence sensor for tetracyclines antibiotics with fast response time(less than 1 s), high selectivity and sensitivity(LODs = 0.08 μmol/L). The fluorescent detection method was successfully used for visual and ultrasensitive detection of ENR, NOR, CIP and tetracycline hydrochloride(TC) in lake water with satisfied recovery from 99.75% to 102.30%. Finally, the photoinduced electron transfer and the competitive absorption of ultraviolet light are the main mechanisms for sensitive detection toward quinolone antibiotics and tetracyclines antibiotics.