Showing 3 results for Torabi
A. Rasooli, H. R. Shahverdi, M. Divandari, M. A. Boutorabi,
Volume 29, Issue 1 (Jun 2010)
Abstract
In this research, the reaction kinetics of TiH2 powder in contact with pure aluminum melt at various temperatures on the basis of measuring the released hydrogen gas pressure was studied. To determine the mechanism the reaction, after Solidification of samples, interface of TiH2 powder in contact with melt was studied. The results showed that PH2-time curves had three regions. In the first and second regions, the rate of reaction conforms to zero and first order, respectively. In the third region, hydrogen gas pressure remains constant and the rate of reaction becomes zero order. In the first and second regions, the main factors controlling the rate of reaction are diffusion of hydrogen atoms within titanium lattice and chemical reaction of titanium with aluminum melt, respectively. Based on the main factors controlling the rate of reaction, three temperature ranges can be considered for reaction mechanism, a) 700-750ºC, b) 750-800ºC and c) 800-1000ºC. In the temperature range (a), the reaction is mostly chemical reaction control. In the temperature range (b), the reaction is diffusion and chemical reaction control, and in the temperature range (c), the reaction is mostly diffusion control.
A. Rasooli, M. Divandari, H. R. Shahverdi, M. A. Boutorabi,
Volume 30, Issue 1 (Jun 2011)
Abstract
In this research, DTA and TGA curves of titanium hydride powder in air with the heating rates of 5, 10, 20, 25, 30ºC/min were drawn, and XRD patterns of titanium hydride powder during heating rate 10ºC/min were prepared. Results showed that hydrogen comes out of titanium hydride in air during seven stages. And, by increasing heating rate, the mechanism of hydrogen emission from titanium hydride is almost fixed. Upon computation of activation energy of these stages, it was revealed that the mechanism does change at different temperatures. According to DTA curve at 10ºC/min, at temperatures lower than 460ºC, the mechanism is controlled by internal diffusion, at temperatures between 460-650ºC, it is controlled by physicochemical process, and at temperatures higher than 650ºC, it is controlled by chemical reaction. By increasing heating rate, the mechanism is changed at higher temperatures.
S. Torabi, S. Khorshidi, A. Karkhaneh,
Volume 39, Issue 2 (Journal of Advanced Materials-Summer 2020)
Abstract
For many years, dexamethasone has been used as an anti-inflammatory drug and is still one of the safest glucocorticoids for treating various diseases. Due to the wide range of the side effects of this drug, it is essential to find a suitable delivering system for reduction in dosage with increased effectiveness. Electrospinning is one of the fiber fabrication methods which is widely used to develop drug carriers due to its ability to load various drugs and biological components and control their release. In this research, neat poly (lactic acid) electrospun fibers and dexamethasone loaded fibers were prepared. To evaluate the effect of polymer concentration on morphology, mechanical properties and drug release profile of the resulting fibers, three polymer concentrations of 10%, 14% and 18% w/v were processed. Thereafter, 5% w/v dexamethasone was added to solutions. The scanning electron microscopy images were investigated to obtain the average diameter of fibers and the average area of pores in each sample. In neat samples, by moving from 10% to 18% composition, the average diameter of the fibers increased by 63.21%. However, in drug loaded samples this increased by 51/19%. After evaluating mechanical properties, an increase of 81/34% in Elastic modulus by moving from 10% to 18% composition was observed. Moreover, the ultimate strength increased by 68/021% when increasing the polymer concentration from 10 to 18%. Drug release from the electrospun samples was continued up to 7 days. Linear release was observed in 10% and 14% compositions. The drug release pattern of these samples was of zero order. Considering the importance of zero order release in different applications of dexamethasone, these delivering systems could be useful. The maximum drug release rate belonged to 14% composition (0.044 1/h).
