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991.
A ketocyanine ligand containing two N-aza-15-crown-5 residues has been synthesized and covalently anchored to a silica substrate through an azomethine link. The ligand formation and molecular structure have been determined by combining spectral data and molecular simulations. Preferential adsorption of rare-earth metals from aqueous solutions to the modified surface has been noticed. In the case of lanthanum, the adsorption is accompanied by significant fluorescence enhancement, which allows this system to be used as a sensor for La3+ ion. 相似文献
992.
L. I. Ochertyanova V. N. Mustyatsa K. Yu. Zhizhin O. N. Belousova N. T. Kuznetsov 《Inorganic Materials》2004,40(2):144-146
The compounds MB10H11 (M = Me4N+, Et4N+, Bu4N+, Ph4P+, Ph4As+) are synthesized. A procedure is proposed for boron determination by atomic absorption spectrophotometry, using microwave processing for sample preparation. 相似文献
993.
A. Yu. Zavrazhnov D. N. Turchen Zh. V. Dobrokhotova V. V. Volkov E. V. Makhonina V. S. Pervov 《Inorganic Materials》2004,40(2):107-114
The GaSe–Ga2Se3 system is studied by x-ray diffraction, electron microscopy, and differential scanning calorimetry. The results demonstrate that the nonadditivity of heat capacity observed near the eutectic composition after quenching is similar to the nonadditivity of properties in misfit layer compounds, which contain incommensurate structural components. The origin of this similarity is discussed in terms of the self-organization of interacting incommensurate elements in the melt and the formation of unstable suprastructural ensembles. 相似文献
994.
A procedure is proposed for evaluating the efficiency of chemical and mineral admixtures in early cement hydration with the use of calorimetric data and with allowance made for the selective effect of admixtures on the hardening process. The concepts of admixture efficiency and admixture–cement compatibility are formulated and are shown to be of practical importance. The proposed approach is substantiated using thermokinetic results on the effects of various admixtures on the hydration of different cements, and the underlying mechanisms are discussed. 相似文献
995.
996.
The theoretical-and-experimental investigation has been performed on the stability of smooth cylindrical shells of steel with a single local dent. All the shells manufactured using the same process were tested with the fulfillment of identical conditions for observations and measurements. Theoretical calculations were carried out by the mesh method with the use of the nonlinear theory of shells. A comparison of the experimental and theoretical values of the critical loads has been made. The theoretical-and-experimental approach proposed enables one to evaluate the quality of shells by studying local dents and other specific imperfections. 相似文献
997.
Stepanov G. V. Kharchenko V. V. Babutskii A. I. Romanov S. V. Feofentov N. A. Kravchenko I. V. 《Strength of Materials》2004,36(3):321-326
The procedure for calculating the life of header – steam generator connector weld joints is proposed. It allows for running out the material plasticity reserve upon static cyclic elastoplastic loading as well as operating conditions, local stress concentrations, and residual stresses after welding. 相似文献
998.
A problem of deformation of a curved shell loaded by internal pressure, axial force, and temperature difference is discussed. Physical equations are derived whereby the displacements and angles of rotation of the line of centers of mass of cross sections of a shell are related to loading parameters. A general constitutive set of equations for a curved element during its deformation is given. Using a method of initial parameters, an analytical solution is obtained for the differential equations for displacements and angles of rotation of the center line allowing for the action of distributed forces and moments. 相似文献
999.
Thin hard coatings fracture propagation during the impact test 总被引:2,自引:0,他引:2
One of the most significant applications of the impact test is to investigate thin hard coatings fatigue properties. Herein the test conditions and duration up to the film damage initiation, are considered in order to determine the critical stresses associated with the coating fatigue strength. Moreover, the subsequent film damage propagation is a significant mechanism as well, since it refers to the ability of the coating to withstand loads after its fatigue damage initiation. In order to describe the film fracture propagation the failed area ratio was introduced and an algorithm to determine this magnitude developed, based on the analysis of imprint scanning electron microscopy graphs. The application of the coating failed area ratio will be demonstrated in various impact test film cases, also with superficial thin layers. The top layers do not affect, in general, the failure initiation of the basic coating. However, according to the obtained results, the superficial films influence the basic coating failure propagation rate during the impact test. 相似文献
1000.
L. N. Dmitruk S. Kh. Batygov L. V. Moiseeva O. B. Petrova M. N. Brekhovskikh V. A. Fedorov 《Inorganic Materials》2007,43(7):793-796
We have studied the effect of In3+, Pb2+, Gd3+, and Cl (heavier ions) substitutions for Al3+, Ba2+, La3+, and F? on the crystallization stability and UV/IR optical properties of HBLAN fluorohafnatc glasses (HfF4-BaF2-LaF3-AlF3-NaF system). We obtained stable glasses containing InF3 and BaCl2 instead of AlF3 and BaF2, respectively, and offering increased IR transmission. The presence of CCl4 in the process atmosphere and the removal of oxygen-containing impurities via directional solidification are shown to have an advantageous effect on the optical quality of the glasses. The fluoride-chloride glasses are capable of accommodating about 1.5 times higher levels of rare-earth activators in comparison with their fluoride analogs. 相似文献