Maximum Values

The effects of doping small amounts of TiO2 up to 5 wt% on the sintering behaviour of alumina (Al2O3) was studied. Green samples were prepared and pressureless sintered in air at temperatures ranging from 1250°C to 1600°C, at a furnace ramp rate of 10°C/min. and soaking time of 2 hours. Sintered samples were characterized to determine bulk density, hardness and Young's modulus. It has been found that all the doped samples exhibited higher bulk density than the undoped samples. The bulk density increases with increasing temperature and attained a maximum value of 3.9 Mgm-3 for samples doped with 1.0 wt% TiO2 at 1450°C. The addition of 1 wt% TiO2 when sintered at 1450°C was found to be the most beneficial throughout the studied range as the samples exhibited the highest Young's modulus of 381 GPa and Vickers hardness of 16.5 GPa as compared to 256.7 GPa and 11.2 GPa for the undoped alumina. Titanium oxide doping is one economical way of improving the densification of Al2O3 without affecting mechanical properties.

http://link.springer.com/chapter/10.1007/978-3-540-69139-6_89

Mechanical respond of the tibiofemoral joint in impact with a rigid plate is the aim of current study. A circular plate with initial velocity hit the tibiofemoral joint. All components all considered as linear elastic material. Cartilages were perfectly attached to the femur and tibia; and while menisci were allowed to move vertically. Circular plate motion was vertically. Femur and tibia if they were target of rigid plate they left free for motion vertically; otherwise, they were fixed at the end. Computed tomography images were used to construct 3-dimentional model of the tibiofemoral joint to analysis in the commercial finite element software package ABAQUS v6.7. We found that during impact depend on the velocity of impactor the contact pressure increased from 0 to maximum value and again descend to 0. Moreover, the maximum contact pressures occur with small time delay in knee joint due to the nature of impact. Regardless types of loading the results were same with some percentage difference. © 2011 Springer-Verlag.

http://link.springer.com/chapter/10.1007/978-3-642-21729-6_44

A series of experiments was conducted to study the CO2 gasification of a deactivated palm-shell-based activated-carbon (ACPS) catalyst used for the thermocatalytic decomposition of methane to produce hydrogen. This catalyst becomes deactivated due to the accumulation of carbon deposits during the methane-decomposition process. The CO2 gasification was carried out at 850, 900, 950 or 1000 °C to study the deactivated ACPS, which was used at methane-decomposition temperatures of 850 or 950 °C. A series of six methane-decomposition cycles at 950 °C alternating with five gasification cycles using CO2 at 900, 950 and 1000 °C was also carried out to evaluate the stability of the catalyst. The experiments were conducted using a thermobalance by monitoring the change in mass of the catalyst with time, i.e., the mass gain during methane decomposition or the mass loss during CO2 gasification. Gasification of the virgin and deactivated ACPS showed strong temperature dependence, with the half and complete gasification times having an exponential dependence on temperature. The gasification reactivity at different conversions was higher for the virgin ACPS and increased with increases in the decomposition temperatures used for deactivation of the ACPS. The activation energies of virgin ACPS and ACPS deactivated at a decomposition temperature of 850 °C decreased with an increase in conversion, while they increased for the ACPS deactivated at a decomposition temperature of 950 °C; the activation energies varied between 81 and 163 kJ/mol. The gasification reactivity changed with methane conversion, showing maximum values for both the virgin and deactivated ACPS at a decomposition temperature of 950 °C. The initial gasification reactivity of the catalyst decreased after three gasification cycles at 1000 °C, while no significant change was observed with gasification cycles at 950 or 900 °C. © 2009 Professor T. Nejat Veziroglu.

http://www.sciencedirect.com/science/article/pii/S036031990901670X 
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