Facile Synthesis of Highly Dispersed and Well-Alloyed Bimetallic Nanoparticles on Oxide Support.

Supported alloy catalysts play a pivotal role in many heterogeneous catalytic processes of socioeconomic and environmental importance. But the controlled synthesis of supported alloy nanoparticles with consistent composition and tight size distribution remains a challenging issue. Herein, a simple yet effective method for preparation of highly dispersed, homogeneously alloyed bimetallic nanoparticles on oxide supports is reported. This method is based on solid solution of metal cations in parent oxide and strong electrostatic adsorption of a secondary metal species onto the oxide surface. In the reductive annealing process, hydrogen spillover occurs from the surface metal with a higher reduction potential to the solute metal in solid solution, leading to metal exsolution and homogenous alloying of the metals on the oxide surface. The ceria-supported Ni-Pt alloy is chosen as a model catalyst and hydrazine monohydrate decomposition is chosen as a probe reaction to demonstrate this method, and particularly its advantages over the conventional impregnation and galvanic replacement methods. A systematic application of this method using different oxides and base-noble metal pairs further elucidates its applicability and generality.

[Influence of Different Types of Dewatering Agents on the Solidification Effect and Physical and Chemical Properties of Sediment].

In order to study the comprehensive effects of different types of dehydrating agents on the dewatering and solidification of dredged sediments, this study took the dredged sediments of Taihu Lake as the research object and selected microorganisms, polymeric iron aluminum salts, organic polymers, organic-inorganic composites, and aluminum salt microorganisms. These five types of composite dehydrating agents were used to conduct a three-month solidification test on the dredged sediment by means of geotechnical pipe bag solidification. The results of the study showed that the dehydration efficiency of organic polymers and organic-inorganic composite chemicals was better. After one month, the water content of sediment dropped to 61.78% and 63.26%, respectively, which then dropped to 40.56% and 32.16% after three months. Compared with that of the unsolidified sludge, the total nitrogen of the bottom sludge after solidification by the organic-inorganic composite agent was reduced by 74.82%, reaching 591 mg·kg-1, primarily due to the reduction in ammonia nitrogen. The solid sludge contained mainly aluminum-bound phosphorus, calcium-bound phosphorus, and iron-bound phosphorus. Among them, four groups (organic-inorganic composite) had the largest reduction in active phosphorus, with the lowest being 64.3 mg·kg-1. In addition, organic polymer agents had the best curing effect on heavy metals, the comprehensive ecological risk index of heavy metals was reduced by 51.3%, and the leaching toxicity concentration was far below the standard threshold. This study showed that organic polymers and organic-inorganic composite medicaments have a better effect on the dehydration and solidification of bottom sludge and thus have good application prospects.

[Location and dilation of the second mesiobuccal canals in maxillary molars.].

PURPOSE: To Locate and dilate the second mesiobuccal canals(MB2) in clinical treatment and in extracted molars in maxillary molars. METHODS: 11 extracted maxillary molars were studied. MB2s were searched and dilate the canals were filled with gutta-percha and then x ray film were taken. 146 maxillary molars included 94 maxillary first molars and 52 maxillary second molars were attempted to locate and dilate for MB2.Then root canal treatment was carried out in molars and x ray film were taken. RESULTS: MB2 canal can be located in 60% and dilate 50% of 10 extracted maxillary first molars. MB2 canal can be located in 44.68% and dilated in 29.78% of maxillary first molars. MB2 canal can be in located in 11.53% and dilated in 7.69% of maxillary second molars. CONCLUSION: The occurrence of MB2 is high in maxillary first molars. Although there are many difficulties in location and dilate of MB2, attempt should be conducted to explore in order to increase rate incidence of root canal therapy.