Existence form of lathanum and its improving mechanism of visible-light-driven La-F co-doped TiO2

The existence form and effect of La on the phase composition,morphology,recombination of photocarriers,and optical absorptivity of La-F codoped TiO2 were investigated.Experimental results indicate that all the phase composition of samples is anatase TiO2,the grain sizes decrease with the increasing of La content The catalysts have a well-defined spherical structure with an average size of 12-14 nm,and the doping elements are uniformly dispersed.Compared with pure TiO2,the absorption edge of La1.5F5-TiO2 red shifts from 388 to 437 nm,accordingly the energy gap(Eg) reduces from 32 to 2.84 eV,Besides,the recombination rate of electron-holes in La1.5F5-TiO2 is the weakest among the prepared samples,and the specific surface area of La1.5F5-TiO2 reaches 105.27 m2/g.The apparent reaction rate constant k of La1.5F5-TiO2 for methylene blue(MB) degradation under visible light obtained from the apparent first-order model achieves 0.0166±0.52 min-1,which is greater than 0.0033±0.09 min 1 of TiO2.Moreover,high-resolution transmission electron microscopy(HRTEM) observation reveals that there coexist La2O3 particles in the co-doped TiO2.

A comparison study of existence forms of Fe species in coke for solution loss reaction of carbon

Fe species were loaded by two different loading ways （absorption method and addition method） to investigate their effect on thermal properties of coke. The particulate coke reactivity of coke samples indicated that the added sample showed higher catalytic activity than the adsorbed sample at first, owing to the decreased structure and properties of coke and more catalytic active sites caused by the strong interaction between Fe species and coke. The presence of Fe species in the added sample weakened the microstructure of coke, and the Fe species were easier to be reduced than those in the absorbed sample due to its different existence form in coke. With further increased loading of Fe species, the different existence positions of Fe species caused more decrease in surface active sites in the added sample than in the adsorbed sample, leading to lower catalytic activity of added sample when the total iron content exceeded 1%. The catalytic mechanism implied that there may be a catalytic dominant factor change in the reaction between the catalytic effect of iron species and carbon surface active sites in coke; the catalytic effect of iron species is dominant in the reaction at first, but the catalytic effect of carbon surface active sites is dominant in the reaction with the further increased loading amount of Fe species.

Existing forms of REE in gold-bearing pyrite of the Jinshan gold deposit,Jiangxi Province,China

Rare earth element(REE) is widely used in various fields of geology.Study of the existing forms of REE in geological objects is a necessity for us to solve geological problems related with REE.This paper tried to make it clear the existing forms of REE in gold-bearing pyrite in Jinshan gold deposit by stepwise dissolution test with ICP-MS analysis.Results showed that content of REE in fluid-inclusions of gold-bearing pyrite was very low,which only took about 0.07%–0.70% of the ΣREE,and that of pyrite phase ...

Studies on Cyclodextrin Inclusion Complex by Fluorescence Anisotropy

An equation for determining the equilibrium association constant (KA) of cyclodextrin inclusion complex with fluorescence anisotropy is derived and used to determine KA of pyrene-B-cyclodextrin inclusion complex. The existing forms of cyclodextrin inclusion complex in solution, the interaction type of host with guest, and the possibility of application of B-cyclodextrin in the analysis of metal ions using naphthalene derivative as a ligand are discussed based on the equation derived along with the curve of fluorescence anisotropy versus cyclodextrin concentration of guest/cyclodextrin system.

NECESSARY AND SUFFICIENT CONDITIONS FOR THE EXISTENCE OF LIAPUNOV FUNCTION OF LUR'E FORM WITH■≤0

This paper is concerned with the problem of absolute stability for a control system with severalexecutive elements. Necessary and sufficient conditions are obtained for the existence of Liapunovfunction of Lur'e form with negative semi--definite derivative (i.e. V≤0).