Infl uences of Iodonium Salts on the Properties of a Hybrid Composite Resin Containing Bis S-GMA and Expanding Monomer Modifi ed Epoxy

In order to reduce shrinkage and improve the mechanical properties of dental composite resins, we designed a hybrid resin formulation containing a novel matrix resin, Bis S-GMA [bisphenol-Sbis（3-methacrylato-2-hydroxypropyl）ether], and epoxy modifi ed by a spiro-orthocarbonate（SOC） expanding monomer. Then, we tested the effects of an iodonium salt, diphenyliodonium hexafl uorphosphate（DPIHFP）, on the properties of the hybrid resin with seven different concentrations. The hybrid resin was polymerized by a ternary photo-initiator system. The volumetric shrinkage（VS）, degree of conversion（DC） and compressive strength（CS） were assessed using Acu Vol^TM, FTIR and a universal testing machine, respectively. The VS, DC and CS were improved with increasing DPIHFP concentration, but a high concentration of DPIHFP had a negative infl uence on the mechanical properties of the hybrid resin and offered no added improvement in the VS and DC. The best performance of a composite resin containing Bis S-GMA and SOC-modifi ed epoxy was achieved with 2wt% DPIHFP. The results also indicated that the resin containing Bis S-GMA was superior to that containing Bis-GMA in terms of VS, DC and CS.

Using Moving North Pacific Index to Improve Rainy Season Rainfall Forecast over the Yangtze River Basin by Analog Error Correction

A new analog error correction （AEC） scheme based on the moving North Pacific index （MNPI） is designed in this study. This scheme shows obvious improvement in the prediction skill of the operational coupled general circulation model （CGCM） of the National Climate Center of China for the rainy season rainfall （RSR） anomaly pattern correlation coefficient （ACC） over the mid-to-lower reaches of the Yangtze River （MLRYR）. A comparative analysis indicates that the effectiveness of the new scheme using the MNPI is better than the system error correction scheme using the North Pacific index （NPI）. A Euclidean distance- weighted mean rather than a traditional arithmetic mean, is applied to the integration of the analog year＇s prediction error fields. By using the MNPI AEC scheme, independent sample hindcasts of RSR during the period 2003-2009 are then evaluated. The results show that the new scheme exhibited a higher forecast skill during 2003-2009, with an average ACC of 0.47; while the ACC for the NPI case was only 0.19. Furthermore, the forecast skill of the RSR over the MLRYR is examined. In the MNPI case, empirical orthogonal function （EOF） was used in the degree compression of the prediction error fields from the CCCM, whereas the AEC scheme was applied only to its first several EOF components for which the accumulative explained variance accounted for 80% of the total variance. This further improved the ACC of the independent sample hindcasts to 0.55 during the 7-yr period.