A novel photoreduction method is presented in this paper for the fabrication of polypyrrole-chitosan (PPy-CS) hollow nanospheres with movable Ag nanoparticles inside (Ag@PPy-CS). Ag nanoparticle is formed by ultraviolet irradiation in the interior of the PPy-CS hollow nanosphere.

Computer simulation is carried out for studying the microphase separation of a two-dimensional diblock copolymer ͑DBCP͒ system under directional quenching. By setting the quenching boundary between the stable and the unstable phase, and shifting the boundary with a constant velocity, the time evolution of the domain morphologies is examined numerically on the basis of the time-dependent Ginzburg-Landau type equation with the free-energy functional for the DBCP. Three different types of morphologies are found for the symmetric ͑i.e., f ϭ0.5͒ DBCP system. One is the irregular lamellar morphology and is essentially equivalent to that produced by homogeneous quenching. The other two are regular and are characteristics of directional quenching process. One of the regular lamellar morphologies is perpendicular to the quench boundary on the average, whereas the other one is parallel to the quench boundary. For the asymmetric DBCP system with f ϭ0.4, which forms the equilibrium morphology of triangular phase, the mode of regular lamellar morphology with the normal of lamellae perpendicular to the quench boundary appears first under the condition of directional quenching when the initial thermal fluctuation is very small. The growth rate of the triangular phase gets faster when the initial thermal fluctuation increases. Therefore, our results reveal that the thermal fluctuation promotes the appearance of the mode of triangular morphology for the case of f ϭ0.4.

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New materials with good purification of water quality (heavy metal ions removal and inhibition of bacteria) have increasingly attracted more research attentions. Considering the advantages of zinc oxide (ZnO) and tea polyphenol functionalized and reduced graphene oxide (TPG), the TPG-ZnO composites were prepared under moderate hydrothermal method and characterized by various methods. Lead ions (Pb2+) and Streptococcus mutans (S. mutans) were used to evaluate the adsorption capacity and antimicrobial activity of the TPG-ZnO, respectively. The influencing factors for heavy metal ions removal (pH, contact time), adsorption kinetics, and isotherms were discussed in this article. Furthermore, their antibacterial properties against S. mutans were investigated by counting of colony-forming units (CFU), scanning electron microscope (SEM) and confocal laser scanning microscopy (CLSM). Results showed that the novel TPG-ZnO composites presented higher adsorption efficiency for Pb2+ (98.92%) compared with pure ZnO and enhanced antibacterial activity effects (99.99%) towards S. mutans, compared with pure ZnO and TPG (P < 0.05). The TPG-ZnO composites are therefore promising water purification materials for application in high-efficient removal of heavy metal ions and inhibition of bacterial growth.

Helicobacter pylori (H. pylori) is transmitted primarily through the oral–oral route and fecal–oral route. The oral cavity had therefore been hypothesized as an extragastric reservoir of H. pylori, owing to the presence of H. pylori DNA and particular antigens in distinct niches of the oral cavity. This bacterium in the oral cavity may contribute to the progression of periodontitis and is associated with a variety of oral diseases, gastric eradication failure, and reinfection. However, the conditions in the oral cavity do not appear to be ideal for H. pylori survival, and little is known about its biological function in the oral cavity. It is critical to clarify the survival strategies of H. pylori to better comprehend the role and function of this bacterium in the oral cavity. In this review, we attempt to analyze the evidence indicating the existence of living oral H. pylori, as well as potential survival strategies, including the formation of a favorable microenvironment, the interaction between H. pylori and oral microorganisms, and the transition to a non-growing state. Further research on oral H. pylori is necessary to develop improved therapies for the prevention and treatment of H. pylori infection.