A convenient adsorption kinetic equation has been offered for the modeling of adsorption kinetics in batch systems when diffusion taking parts to the rate-controlling step of adsorption. This model is suggested based on the Smoluchowski-Waite equation for diffusion-controlled second-order reactions. The proposed new model has better performance (lower absolute values of the relative errors (AARE) %) respect to the pseudo-second-order. Results of this equation are in agreement with experiment data especially at the initial times of adsorption that diffusion contributes to the rate-controlling step of adsorption.

In this paper, diffusion bonding of dense alumina bodies using hydride nanopowders mixture as the interlayer was investigated. Mixture of aluminum hydride and magnesium alanate was synthesized via mechano chemical activation process. Aluminum and magnesium chloride and lithium alanate were used as precursors. Products of milling process were consisted of nano sized alane and Mg alanates. Alumina bodies were diffusion boned at 300, 350, 400, and 450oC, under pressure of 20 Mpa for 30 min dwelling time using custom designed induction hot press.Dissociation of hydride mixture interlayer during diffusion bonding process produced in-situ nanosized alloyed aluminum and aluminum-magnesium intermetallic without any surface oxides. Combination of stoichiometric and non-stoichiometric spinel, oxide, and free metal structures were formed during bonding process. The highest bond strength was about 196 MPa via formation of Mg-Al spinel oxide during bonding at 450oC.

Production of grey cast iron with improved mechanical properties and low cost is an import ante challenges of these engineering materials. In this study, AISI 1045 steel chips were used for reinforcing of hypoeutectic grey cast iron and microstructure and mechanical properties of composites produced by dry sand casting has been studied. A specimen without reinforcement and two composite specimens, respectively, with 1.5 and 3 volume percent of chips were produced. Microstructural studies were carried out by light and scanning electron microscopy. Noticeable region between steel chip-reinforcement and cast iron is observed that it is a diffusion Interface. In the Interface, carbon and .silicon are diffused from cast iron to steel chips and this case to form of a clear Interface. To determine the mechanical properties of produced specimens are used for the tensile and hardness tests. Results were shown that reinforcing of cast iron by steel chips is resulted in to increase of the strength and hardness.

In this research, the diffusion bonding of the stabilized zirconia ceramic and Nimonic 105 superalloy using Ti/Nb/Ni multi-interlayer was carried out. Joint was performed using the plasma spark technique in a vacuum atmosphere and at different temperatures and times. The microstructure of the different joint zones was studied using optical and FESEM microscopes equipped with an EDS analyzer. The results showed that the critical region is Ti/3YSZ Interface and in all conditions diffusion bonding in Ti/Nb, Nb/Ni, and Ni/NI 105 Interfaces were done. Microstructural observations showed that in the Ti/3YSZ Interface at all temperature and time conditions, the connection of two separate regions including Ti3O and (Zr, Ti)2O was formed due to the difference in the diffusion depth of Ti, Zr, and O elements and with increasing temperature and time, the thickness of these regions increased. Microstructural studies showed that the bond at 900 ℃ and 30 minutes did not have any cracks and discontinuities and due to the better diffusion of atoms, a suitable reaction layer was formed. Microhardness observations and EDS analyses confirmed that the Ti3O reaction layer is the weakest zine.

Dissimilar joining of Al5083 to MgAZ31 was performed through friction stir welding (FSW) and diffusion bonding (DB). A constant tool rotation rate of 400 rpm and travel speed of 50 mm/min was used for FSW. The peak temperature of this specimen was raised to maximum of 435° C at the advancing side of the FS weld. Thermal cycle of the FSW specimen showed a distinct plateau at about 430 ° C, lasting for about 8 s. At the travel speed of 50 mm/min, the distance corresponding to 8 s is about7mm, which is the pin diameter. The presence of the temperature plateau indicates that the temperature at eachthermocouple remained constant as the pin passed it. It further indicates that a eutectic reaction probably occurred, and kept the temperature constant as the pin passed by. The weld had anirregular shaped region in the weld center of DB weld and, having a different microstructure and hardness from the two base materials. The irregular shaped region in DB weld, contained a large volume of intermetallic compound Al12Mg17. The present study suggests that constitutional liquation and solid state diffusion at the Interface resulted in the intermetallic compound formation in the weld center.

Background: Prostate cancer is the third leading cause of death and is the most common cause of cancer in elderly men. Regarding to the low accuracy of screening methods such as prostate-specific antigen (PSA), Digital Rectal Examination (DRE) and trans rectal ultrasound (TRUS) in detection and localization of tumor, Magnetic Resonance Imaging (MRI) and diffusion Weighted Imaging (DWI) attracted many attentions in the past years. DWI reveals micro-molecular diffusion, which is the Brownian motion of the spins in biologic tissues. This technique can delineate pathologic lesions with high tissue contrast against generally suppressed background signal. In this paper, the value of DWI in detection of prostate cancer is studied.Methods: In this cross-sectional study, the studied population are suspicious patients to prostate cancer based on high Prostatic Specific Antigen level or abnormal Digital Rectal Examination who refered for prostate biopsy to radiology department of Hazrate- Rasoul Hospital during the year 2011. The results of DWI are compared to biopsy results for all patients.Results: Eighty five patients are selected. The DWI sensitivity in detecting of prostate cancer is 100%, specificity 97.1% and positive and negative predictive values are 89.5% and 100%, respectively. The results showed that if DWI reports the prostate cancer as negative, the result was highly reliable and if it reports as positive, although the report was not 100% reliable, but it still had high reliability, more than 90%.Conclusion: DWI had high accuracy in detecting prostate cancer for patients with cancer. Also the accuracy of this method for patients without prostate cancer was acceptable compared to the other common methods.

Background: Multiple sclerosis (MS) is a chronic disease that begins most commonly in young adults and is characterized pathologically by multiple areas of central nervous system (CNS) white matter inflammation, demyelination, and glial scarring. The most valuable aid for diagnosis is magnetic resonance imaging (MRI). New type of MRI has been developed on the basis of molecular diffusion which capable of detecting acute and active lesions. Early diagnosis and treatment is possible to stop or slowdown progression of disease. The aim of this study is to compare the findings of conventional and diffusion- weighted (DW) MRI in detection cerebral lesions of MS.Methods: Thirty patients with clinically definite MS and 30 healthy volunteers were studied in a descriptive-prospective survey over a twelve-month period of time.Conventional and DW MRI were used in both groups. Total number, morphology, location and the mean size of the intra-cerebral plaques of MS were compared between group. The sensitivity and the specificity of both imaging methods in detecting these plaques were determined.Results: Thirty patients with MS with the mean age of 32.76±8.79 years and 30 healthy individuals with the mean age of 32.75±9.23 years were enrolled. Plaque within the brain was significantly higher by the conventional method (P<0.05). Ovoid lesions were greater in number in the conventional method group. More lesions were detected by the conventional method in the areas of periventricle, centrum semiovale and corpus callosum. Regarding the size of plaque, the minimum measurement was significantly lower in the conventional method group. The sensitivity of both methods was 100%. The specificity of conventional and DW MRI was 86.6% and 96.6%, respectively.Conclusion: In our study the sensitivity of both methods was the same but the specificity of DW MRI was higher. DW MRI may detect lesions which are not detectable by the routine methods.

In this study, the effect of temperature on the microstructure and reactive layer at the Interface between the Ti interlayer and the base metal related to the diffusion bonding of Zr702 to A516 low alloy steel was investigated. The joining was done using the spark plasma sintering technique at temperatures of 900, 950 and 1000°C for 30 minutes. Field Emission Scanning Electron Microscope (FESEM) equipped with EDS analysis was used to investigate the microstructure of the Interfaces in various joints. Investigations showed that at all temperatures, with the diffusion of atoms and the formation of a reactive layer between the Ti interlayer and Zr702, no intermetallic phases, cracks, porosity and discontinuities were formed at their Interfaces. . It was found that increasing the bonding temperature did not cause the formation of new phases and compounds in the Interface and only increased the thickness of the reaction layer. The measurement of the thickness of the reactive layer showed that the maximum and minimum amounts of diffusion were 84 microns at 1000 °C and 64 microns at 900 °C respectively.