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Sulfoaluminate cement-based high-water materials are widely used in coal and metal mining. There are few reports on the water cement ratio (W/C) affecting the properties and progress of hydration on dual liquid cement-based materials. Here, the effects of different W/C on dual liquid cement-based material on setting time, viscosity, compressive strength, water loss rate, diffusion radius, hydration heat, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction and SEM tests were studied. The results showed that as the W/C increased, the setting time increased, and the viscosity of single slurry decreased. Furthermore, as the slurry X and Y were mixed, the viscosity had an inflection point, and the compressive strength decreased while the later strength slowly increased; the relative water loss rate within 60 min reached 2.3–2.6, and was essentially stable after 40 h when the water cement ratio increased from 5:1, 6:1, 7:1, 8:1 to 9:1. When W/C = 8:1, it can be considered a turning point; the formula of diffusion radius obtained by experiments showed that the accumulative heat release and heat flow rate obviously decreased when the W/C was greater than 8:1. Also, the analysis results of XRD and SEM indicated that ettringite was the main hydration product, and as the W/C decreased, its density and shape also changed.

Karst collapse column is a serious geological disaster in China’s coal mines. There are various karst collapse columns in coal mine areas, such as Huainan, Huaibei, Xingtai, Lu’an. And they have seriously affected mining safety and geological environment. The present research is focused on analyzing subsidence mechanism and dynamic collapse process. Based on mechanical analysis of thin plate theory, a detailed model of collapse column slipping and bending fracture is constructed to gather the critical conditions of the collapse column roof. The sensitivity parameters analysis shows that both the radius and roof thickness of cave have a great influence on the sliding instability and bending fracture. Meanwhile, the buried depth also affects bending failure. The discontinuous deformation analysis (DDA) method is used to simulate and analyze the collapse process. The numerical results indicate that the stability of inverted funnel collapse column is dominated by the bending stress of roof strata. The movement of columnar collapse column is mainly caused by sliding instability. However, the funnel collapse column is relatively stable, and does not change in the same condition. The displacement field analysis shows that the collapse range of inverted funnel collapse column is obviously larger than that of columnar collapse column, in which its maximum displacement is approximately 1.5 times that of the columnar collapse column. There is no large area collapse on the upper part of the funnel collapse column, and the block system is relatively stable. The principal stress field analysis proves the above results.

TiO2:Co thin films of high Co concentration were investigated by the high resolution transmission electron microscopy, physical property measurement system and energy dispersive X-ray. The as-deposited films are amorphous magnetic semiconductors and we did not find any Co metal particles in them. The electronic transport process in the low-temperature range below 80 K could be described by the spin-dependent variable-range-hopping process. However, after the samples were annealed at 300 °C, large amounts of Co metal particles were observed to connect each other and the films show a metallic behavior. The origin of ferromagnetism of the thin films is also discussed.r 2006 Elsevier B.V. All rights reserved.

TiO2/CO thin films were prepared on glass substrates under thermal non-equilibrium condition by alternately sputtering very thin TiO2 and Co layers for 60 periods. Microstructure and composition analyses by X-ray diffraction, transmission electron microscopy, X-ray photoemission spectroscopy and electron energy-loss spectroscopy indicated that the Co element was incorporated into TiO2 to form the Ti1-xCoxO2 magnetic semiconductors. The obvious Kerr rotations in the samples were observed, and the relation between the Kerr rotation and Co concentration was discussed. (c) 2006 Elsevier B.V. All rights reserved.

TiO2-based magnetic semiconductors with high Co doping concentrations (Ti1-xCoxO2) were synthesized under thermal nonequilibrium condition by sputtering machine. Microstructure and composition analysis by transmission electron microscopy, x-ray photoelectron spectroscopy, and electron energy-loss spectroscopy indicated that Co element was incorporated into TiO2 to form Ti1-xCoxO2 compound. The direct evidence for the compositional inhomogeneity of the Ti1-xCoxO2 compound was given. Room temperature ferromagnetism with high magnetization was obtained, which could be attributed to the intrinsic properties of the amorphous magnetic semiconductor. The electrical transport in a low temperature range was explained by spin-dependent Efros's variable range hopping, and correspondingly an exponential function of the magnetoresistance versus T-1/2 was found. (c) 2006 American Institute of Physics.

The molecular orbital (MO) reactivity indices of a new potent reversible anticholinesterase (anti-ChE) agent, Suberogorgin (S), and its derivatives (S-E; S-OH, α and β forms; S-H, α and β forms also) were calculated using the MNDO method; and their anti-ChE activities against Torpediniforms Narcline timilei (Torpedo) acetylcholinesterase (AChE) were studied. It was found that the energy of lowest unoccupied MO (E lumo ), nucleophilic frontier orbital charges (f n r) of C4 and C5 (double bond) and the net charges of C9 (carbonyl carbon) andC13 (carboxyl carbon) were related to the anti-ChE activity of S. By esterification of the carboxyl group, hydrogenation of the double bond or reduction of the carbonyl group, the MO reactivity indices will be changed and, then, the anti-ChE activities will be weakened. On the basis of the structure-activity relationship (SAR) of S and its derivatives, the active groups of S were sought and a possible schematic diagram of the interaction of S with the active sites of AChE was suggested.