Staphylococcus aureus can cause numerous different diseases, which has been attributed to its large repertoire of virulence factors, many of which are under the control of the accessory gene regulator (agr) quorum sensing system. Under conditions of high cell density, agr increases the production of many virulence factors, decreases expression of several colonization factors, and is intimately associated with the pathogenesis and biofilm formation of S. aureus. This review summarizes our current understanding of the molecular mechanisms underlying agr quorum sensing and the regulation of agr expression. The discussion also examines subgroups of agr and their association with different diseases, and concludes with an analysis of strategies for designing drugs and vaccines that target agr to combat S. aureus infections.

With increasing health consciousness, Y 2 O 3 -based rare earth nanophosphors are considered as promising luminescent complexes for bio-applications. In the present study, an atmospheric pressure plasma-electrochemical technique is demonstrated for the synthesis of Eu 3 + /Tb 3 + single-doped or co-doped Y 2 O 3 nanophosphors from merely an aqueous solution of the corresponding rare earth nitrite salts. Systematic experiments were performed to prepare (Y 1-x-y Eu x Tb y ) 2 O 3 nanophosphors of various Tb 3 + and Eu 3 + ratios (x:y = 1:0, 2:1, 1:1, 1:2, and 0:1), with the ultimate goal to achieve the colour tunability by simply adjusting the dopant compositions. Results indicated successfulness synthesis of crystalline Eu/Tb single-doped and co-doped Y 2 O 3 nanophosphors with Tb 3 + and Eu 3 + ions being uniformly incorporated into the Y 2 O 3 host matrix. The generated products showed apparent downshift behaviour under ultraviolet irradiation, and characteristic spectral excitation and emission bands were detected by the photoluminescence measurement. Furthermore, by adjusting the relative composition ratios of the terbium and europium ions, the emission colours were shown to be regulated to a large extent. The demonstrated process can be characterized as simple, versatile and environmentally-friendly, featuring great flexibility in colour tunability, and therefore can present a considerable interest for emerging nanofabrication applications.

Effect of different curing conditions on the mechanical properties of magnesium phosphate cement (MPC), and the water resistance of MPC was improved by adding slag, the influence of slag on component and microstructure of the hydrated product were studied in this paper. The additive amount of slag was 0% ,10% , 20%, 30% and 40% separately in the ratio of total amount of MPC. It indicates that the compressive strength and flexural strength increase by about 30%,40% when the amount of slag reaches 10% of phosphate cement, respectively , and the dissolution of some phosphate which has not reacted can be prevented when cured in water for days, it improves the pH value of the solution, so the main hydration product-MgKPO4·6H2O hard to be dissolved under alkaline environment resulting in the decreasing of porosity ,and the decrease of strength would be controlled.