Abstract Experimental data of hydrolytic polymerization of lanthanide ions in aqueous solution were treated by graphic method, computer fitting and pq analysis, species present were ascertained and hydrolysis constants obtained. Ln (OH) 2+ and Ln 2 (OH) 2 4+ predominated in the species of all hydrolysis products. When the first and the second hydrolysis constants were plotted against radii and effective nuclear charge of lanthanide ions, the curves obtained conformed with the “three‐division groups” rule. Correlation between hydrolysis constants of Ln 2 (OH) 2 4+ and other hydrolysis constants is linear. Using the above empirical correlations we calculated hydrolysis constants of all lanthanide ions and obtained satisfactory results which showed good regularity for hydrolysis of lanthanide ions and thus systematized all data of the reaction.
Ultrasonic is one of the well-known methods for surface roughness measurement, but small roughness will only lead to a subtle variation of transmission or reflection. To explore sensitive techniques for surfaces with small roughness, nonlinear ultrasonic measurement in through-transmission and pulse-echo modes was proposed and studied based on an effective unit-cell finite element (FE) model. Higher harmonic generation in solids was realized by applying the Murnaghan hyperelastic material model. This FE model was verified by comparing the absolute value of the nonlinearity parameter with the analytical solution. Then, random surfaces with different roughness values ranging from 0 μm to 200 μm were repeatedly generated and studied in the two modes. The through-transmission mode is very suitable to measure the surfaces with roughness as small as 3% of the wavelength. The pulse-echo mode is sensitive and effective to measure the surface roughness ranging from 0.78% to 5.47% of the wavelength. This study offers a potential nondestructive testing and monitoring method for the interfaces or inner surfaces of the in-service structures.
Abstract Due to their excellent properties, polymides (PIs) result promising as high-performance materials in different technological fields. In this research, both micron-sized tubular mesoporous silica (mSiO 2 ) and double-tube tubular diatomite particles with cadmium sulfide quantum dots are prepared by chemical deposition method. A cluster of type fluorescent particles is prepared by self-assembling carbon quantum dots (CDs) on the inner surface of the above materials. Then, a fluorescent polyimide film is prepared by uniform dispersion of fluorescent particles. The study of different properties of the film becomes then mandatory to evaluate possible application perspectives. Therefore, after synthesizes, all samples were investigated in term of chemical structure, microstructure and fluorescence properties by infrared spectroscopy, x-ray diffraction, scanning electron microscopy and fluorescence spectrophotometry. Fluorescence performance of diatomite-based fluorescent particles (diatomite@CdS@CDs) results not as good as the mSiO 2 -based fluorescent particles (mSiO 2 @CdS@CDs) ones; the mechanical properties of the composite film deteriorate as the content of the inorganic component increases. The performance of PI/mSiO 2 @CdS@CDs is 7.6 times the PI/diatomite@CdS@CDs ones.
Various metal (Cr, Mn, Fe, Co, Ni, Cu, Zn, Ag, Sn, La) ferrocyanides and ferricyanides may be considered as a multibond activation model of bimetal coordination, since CN− acts as a typical ambident ligand bonded at the two ends with two metal ions. In accordance with hydrogenation reactions of CN− taking place during thermal decomposition in hydrogen, the activation effect of bimetal coordination and the mechanism of hydrogenation reaction of CN− are discussed from the viewpoint of the crystal structure and the electron structure of the complexes. The activation degree of CN− bonded with various metal ions has been investigated. It was found that the temperature at which the triple bond of CN− breaks with top speed to evolve NH3 correlates closely with the standard electrode potential, and d electron configuration of the metal ions.
Abstract In this paper, benzene adsorption isotherm and their hysteresis on two important local diatomites were determined at 25°C, and their silicon hydroxyl group (SiOH) number was determined, their properties were reported, and the relationship between surface structure, surface SiOH number per nm 2 and adsorption isotherm with hysteresis was discussed. The specific surface was also calculated from the isotherms, and pore‐size distribution was determined.
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