This study presents a new method in synthesis of nano uranyl Schiff base complexes. In this method slow addition of dilute uranyl(VI) acetate solution to dilute Schiff base solution following the reflux for about 24 h, yields nano uranyl(VI) Schiff base complexes. Characterization of Schiff base ligands and nano uranyl complexes has been done using 1H NMR, IR, UV–vis spectroscopy, elemental analysis. Schiff base ligands were synthesized by the condensation of one mole 3,4-diaminobenzophenone and two moles salicylaldehyde or substituted salicylaldehyde (3-OMe, 4-OMe, 5-OMe, 5-Br, 5-Cl). The electrochemical properties of the uranyl(IV) complexes were investigated by cyclic voltammetry. A good correlation was observed between the oxidation potentials and the electron withdrawing character of the substituents on the Schiff base ligands, according to the following trend: 5-MeO < H < 5-Br ≈ 5-Cl. Also the effect of the position of the substituted groups of Schiff base on the anodic potentials is as follows: 5-OMe < 3-OMe < 4-OMe. 相似文献
Controls to protect the historic environment have developed relatively late in Australian cities. The earliest and subsequently most comprehensive evolved in the state of Victoria, especially in the inner suburbs of the state capital, Melbourne. These controls have two basic forms; specific site registration and protection and broader planning control. While the controls have developed amidst some criticism and opposition, they appear currently to be well accepted and to be making a positive impact. 相似文献
The main goal of this study is to assess and compare three advanced machine learning techniques, namely, kernel logistic regression (KLR), naïve Bayes (NB), and radial basis function network (RBFNetwork) models for landslide susceptibility modeling in Long County, China. First, a total of 171 landslide locations were identified within the study area using historical reports, aerial photographs, and extensive field surveys. All the landslides were randomly separated into two parts with a ratio of 70/30 for training and validation purposes. Second, 12 landslide conditioning factors were prepared for landslide susceptibility modeling, including slope aspect, slope angle, plan curvature, profile curvature, elevation, distance to faults, distance to rivers, distance to roads, lithology, NDVI (normalized difference vegetation index), land use, and rainfall. Third, the correlations between the conditioning factors and the occurrence of landslides were analyzed using normalized frequency ratios. A multicollinearity analysis of the landslide conditioning factors was carried out using tolerances and variance inflation factor (VIF) methods. Feature selection was performed using the chi-squared statistic with a 10-fold cross-validation technique to assess the predictive capabilities of the landslide conditioning factors. Then, the landslide conditioning factors with null predictive ability were excluded in order to optimize the landslide models. Finally, the trained KLR, NB, and RBFNetwork models were used to construct landslide susceptibility maps. The receiver operating characteristics (ROC) curve, the area under the curve (AUC), and several statistical measures, such as accuracy (ACC), F-measure, mean absolute error (MAE), and root mean squared error (RMSE), were used for the assessment, validation, and comparison of the resulting models in order to choose the best model in this study. The validation results show that all three models exhibit reasonably good performance, and the KLR model exhibits the most stable and best performance. The KLR model, which has a success rate of 0.847 and a prediction rate of 0.749, is a promising technique for landslide susceptibility mapping. Given the outcomes of the study, all three models could be used efficiently for landslide susceptibility analysis.
The contribution of the vortex Rossby wave (VRW) to framework of a barotropic non-divergent TC-like vortex model. the spiral rainband in the tropical cyclones (TCs) is studied in the The spectral function expanding method is used to analyze the disturbance evolution of a defined basic state vortex. The results show that the numerical solution of the model is a superposition of the continuous spectrum component (non-normal modes) and the discrete spectrum component (normal modes). Only the eyewall and the rainbands in the inner core-region in a TC are related to the VRW normal modes, whereas the continuous spectrum wave components play an important role in the formation of secondary-, principal-, and distant- rainbands, especially the outer rainband, through an indirect way. The continuous spectrum can promote the development of the TC circulation for the occurrence of a mesoscale instability. The convection under a favorable moisture condition will trigger the inertial-gravitational wave to cause the formation of unstable spiral bandliked-disturbances outside of the eyewall. The complicated interaction between the basic state-vortex and the VRW disturbances will cause a positive feedback between the TC circulation and the rainband. 相似文献
This paper examines unbalanced urbanization process in Fujian province from 1982 to 2010 from the perspective of dual-track urbanization. The analysis is mainly based on 67 county-level units. The spontaneous track of urbanization is a new process of urbanization in China emerged in the reform period. It plays an important role in linking urban and rural areas but also creates problems of rural-urban integration and social cohesion. This paper examines the relative roles of spontaneous and state-sponsored urbanization and their impacts on the spatial pattern and structure of urbanization in Fujian. It is found that rural to urban migration plays the most significant role while state-sponsored urbanization and rural urbanization play equal roles in the process of urbanization. There was a significant shift of state-sponsored urbanization from county-level cities and counties to urban areas of central cities, Fuzhou and Xiamen, and from inland area to coastal area after 1990. There have also been significant shift and growth of temporary population towards the central cities in the reform period. The shift from small towns to large urban areas is clear in both tracks of urbanization. 相似文献
By taking the panel data of China mainland from 1996 to 2010 for an example, this paper used ESDA, gravity center and standard deviation ellipse to analyze the spatial differences, combined with the impulse response function to propose the infl uence mechanism of spatial evolution. The results showed that the provincial tourism economy generally showed a random spatial distribution and the spatial differences had narrowed from 1996 to 2010. The differences of tourism development in east China are the largest, and differences of the middle China are the smallest. The gravity center of Chinese provincial tourism has shifted to the northwest, the HH district concentrated in the Yangtze River Delta and its surroundings, the LL district concentrated in west Chinese. The high-value areas of city tourism economy are broadly distributed in the right of line "Heihe–Tengchong", mainly concentrated in four plates. Compared with spatial differences of provincial tourism economy, those of city tourism economy were more signifi cant. Regional tourism resources and social economic factors are the two major factors that infl uence spatial differences of tourism economy, the objective rule and policy and institution also have a great impact on regional tourism development differences. Special events may have a certain impact on the pattern of the original; however, it cannot change the spatial pattern completely. 相似文献