Talesh, S. Siamak Ashraf
Hashemi, S. J.
Impact of Si/Al ratio on the adsorption capacity and separation selectivity of CO2/CH4 in SAPO-34 has been investigated. SAPO-34 samples were synthesized with two Si/Al ratios (0.2 and 0.3). A batch adsorption volumetric apparatus was used to measure the adsorption equilibrium capacity and derive the equilibrium isotherms. The tests were performed in a wide range of pressure from normal to 3000kPa and three levels of temperatures from 277 to 298K. Results proved decreasing Si/Al ratio, from 0.3 to 0.2, improved CO2 separation from CH4.
Hashemi, S. J.
The platinum (Pt) diffusion gas electrodes are frequently used in chlor-alkali process industry. The platinum (Pt) diffusion gas electrodes used in advanced chlor-alkali process has encountered many disadvantages such as flooding, which is the result of peroxide production phenomenon. The flooding reduces the process efficiency. In this article new electrodes are used to overcome some of the above-mentioned disadvantages to increase efficiency. The effects of seven process parameters are also individually studied. The results show the brine concentration increase CCE by increasing, anolyte, oxygen temperatures, and flow rates. The brine concentration decreases as the current density increases. The Ru/C catalyst performance is higher than Pt/C catalyst. Besides, Ru effectively prevents the aggregation and growth of platinum nano-particles in the thermal heating process. The higher activity, good stability, and the better caustic current efficiency of the Ru/C catalyst make it more suitable cathode in advanced chlor-alkali process.
During through air drying the internal sheet drying history develops as a succession of local moisture content profiles in the sheet thickness dimension. These profiles were determined by interrupting the through drying of 180 g/m(2) 6-ply sheets, then quickly delaminating and determining the moisture content of each 30 g/m(2) ply. On the through flow inlet side of the sheet, large moisture differences, about 0.4-0.6 kg/kg dry per 30 g/m(2) ply, develop and move into the interior of the sheet provided that local moisture content is in the range 0.45-1.75 kg/kg. On the through flow exit side, moisture gradients only become significant for moisture content below about 1.25 kg/kg. From the through flow exit side of the sheet much of the water is removed by diffusion to the (low entry side where most evaporation into the through flow occurs. The kinetics of through drying reflect the interaction between these two mechanisms, local evaporation into the through flow and thickness direction diffusion. The moisture diffusivity-moisture content relation controls this balance. In any combination with cylinder drying to give some kind of hybrid dryer, through drying should be at the dry end where air permeability is highest and cylinder drying rate is lowest.
Hashemi, S. J.
Naeini, H. Moslemi
Liaghat, G. H.
Tafti, R. Azizi
Warm hydroforming is used widely to increase the formability of aluminum and magnesium tubes. Prediction of forming limit is a vital problem in designing the warm hydroforming process of tubes. In this paper, bulge height of aluminum tubes AA6063 is predicted using ductile fracture criteria at high temperatures. Ductile fracture criteria were calibrated by performing several uniaxial tensile tests at different temperatures and strain rates. Fracture strain and work functions were obtained based on Zener-Holloman parameter. Free bulging process of tubes was simulated using finite element method and different loading curves were used to bulge the tubes. Prediction of ductile fracture was compared with the experimental results measured on a warm free bulging set-up. The comparison shows that Ayada ductile fracture criterion is able to predict the bulge height of aluminum tubes at high temperatures. (C) 2014 Politechnika Wroclawska. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.
Local nonuniformity of moisture content during drying is doubly disadvantageous. Moisture nonuniformity reduces drying effectiveness, increasing drying cost or reducing drying capacity, and may decrease product quality for printing through effects such as cockling and curl. These problems can occur with the now dominant process of cylinder drying, but become much more acute with the various higher intensity drying techniques which are competing to become elements of the higher speed hybrid dryer sections of the future. For quantitative characterization of moisture nonuniformity a novel method applicable to paper being dried by various processes was developed, then demonstrated for one high intensity air convection process, through air drying. During drying, the local moisture content was determined for many 2.5 mm diameter sensing areas by very rapid scanning with a custom design 3-wavelength infrared paper moisture instrument. For local moisture nonuniformity thus determined, the coefficient of variation provides a standard basis for comparison between paper types and drying conditions. For kraft paper from 20 to 120 g/m(2), the effects on local moisture nonuniformity were evaluated for drying intensity and for several paper parameters-formation, grammage, and initial moisture content. The drying nonuniformity index was found to parallel both formation quality and drying intensity. An unexpected finding was that over the 20-120g/m(2) range, local moisture nonuniformity passes through a maximum at 30 g/m(2). Sheet initial moisture content produces the largest effect, with moisture nonuniformity index being both high and very sensitive to this parameter for initial moisture content above the fibre saturation point. Another finding from these unique measurements is that, for the same 2.5 mm diameter sensing areas, there is a clear correlation between moisture nonuniformity index and local grammage.
Ghazvini, R. D.
Hashemi, S. J.
Yekaninejad, M. S.
Background. - Dermatophytosis is a frequent cutaneous infection affecting the keratinized tissues of humans, pets and livestock. Animals can carry dermatophytic elements asymptomatically and are considered to play an important role in the epidemiology of the disease. As exposure to any infected lesion free animals, especially cats, may lead to the development of infection in humans. Objectives. - This study was done to determine the frequency of fungal agents isolated from skin and hair of cats living in rural areas of Meshkin-shahr, Iran. Animals. - A total of 103 asymptomatic cats living in rural areas of the region were studied. Methods. - This cross-sectional descriptive study was performed in Medical Mycology Laboratory, School of Public Health, Tehran University of Medical Sciences from February 2015 to July 2016. A total of 103 asymptomatic cats were studied. Mycological analysis including direct examination and culture on SC, SCC and DTM of the collected samples were conducted. For molecular confirmation when needed, panfungal PCR targeting the ITS1 region of the rDNA gene cluster using primers ITS1 and ITS4 were performed. Gender and age were also recorded. Results. - None of the 103 cats examined were positive for fungal elements on direct examination. However, 15 (14.5%) cases showed dermatophytes growth. T. verrucosum was the most common etiologic agents of dermatophytosis. Although the gender of the cats had not significant association with dermatophytosis prevalence, age was a significant influential risk factor (P =3D 0.019). Aspergillus spp., Alternaria spp., Rhizopus spp., Penicillium spp.and paecilomyces spp. in descending frequency were the most predominantly identified saprophytic fungi. Conclusion. - Our findings clearly highlighted the epidemiological role of asymptomatic cats in spreading dermatophytosis to humans and other animals. (C) 2019 Elsevier Masson SAS. All rights reserved.
Talesh, S. S. Ashraf
Hashemi, S. J.
Fine crystals of SAPO-34 were synthesized by preparation of sol-gel precursor and hydrothermal process. The produced crystalline phase and the crystal shapes were analyzed by XRD patterns and SEM images. The core-shell adsorbent was prepared by the formation of the fine layer of SAPO-34 on the surface of the inert ceramic particles using the same synthesis parameters and hydrothermal conditions by in situ crystallization. The prepared core-shell SAPO particles were tested in dynamic adsorption experiments of a mixture of 5% CO2 and 95% CH4 at 298K and 0.1MPa, and their performance was compared with pure powders of SAPO-34 in the same adsorption operational conditions. The longer breakthrough time, sharper breakthrough curves, and higher CO2 adsorbed amount were observed using core-shell SAPO-34 particles as adsorbent rather than using pure particles of SAPO-34. It is concluded that the production of a thin layer of SAPO-34 on cheap and inert porous ceramic particles is preferred rather than using higher amounts of SAPO-34 powders pelleted or binded with inert material in dynamic adsorption processes for the separation of CO2 from natural gas.
The SAPO-34 catalyst was synthesized by the combination of TEAOH and morpholine templates, and colloidal silica and silicic acid, as the silica source under hydrothermal conditions. The effect of the template molar ratio and silica source on the physicochemical properties of each catalyst was studied by XRD, SEM, BET and TPD techniques. XRD patterns revealed the significant effect of gel composition on the crystallinity and particle size of the samples. SEM photos showed that all the catalysts have cubic morphology, but their particle size was different. According to the XRD and SEM of the catalyst prepared by silicic acid, this catalyst showed low crystallinity and large crystal size. TPD analysis indicated that the acidity reduced by increasing the morpholine content in the reaction mixture. The catalytic performance of the synthesized catalysts was tested in MTO reaction. The catalyst produced by the TEAOH/morpholine ratio of 0.5:1.5 exhibited the highest light olefins yield, as well as the longest catalyst lifetime. The maximum yield of ethylene and propylene was determined to be 94 wt%, with 100% methanol conversion. (C) 2012 Sharif University of Technology. Production and hosting by Elsevier B.V. All rights reserved.
Afshari, S. Agha Kuchak
Hashemi, S. J.
Ghazvini, R. Daie
Gharehbolagh, S. Aghaei
Background. - In immunocompromised patients suffering from invasive fungal infections, rapid identification of fungal species is important since the appropriate treatment is usually related to the responsible species. We describe here, an assay based on combination of PCR and reverse line blot hybridization (PCR/RLB) for differentiation causative agent of fungal infections. Materials and methods. - We performed PCR/RLB assay on 10 reference strains, which include Aspergillus species (A. fumigatus, A. flavus, A. niger, A. terreus, and A. clavatus), Mucor circnelloides, Rhizopus oryzae, Alternaria alternata, Cladosporium herbarum, and Fusarium solani. Besides, twenty-two clinical specimens from patients with proven fungal infections were analyzed for the identification of species. The obtained results were then compared with the results of culture and sequence analysis. Results. - The fungal species specific oligonucleotide probes were able to distinguish between all species represented in this study with the exception of cross-reactivity between A. niger and A. fumigatus species. Two specimens, which were represented as mixed fungi in culture, were identified properly by this method. Results of the RLB assay were concordant with the culture and ITS sequencing results. Conclusion. - Our result demonstrate that the RLB assay potentially is suitable for rapid and simultaneous identification of variety fungal pathogens directly from culture as well as from clinical specimens. (C) 2017 Elsevier Masson SAS. All rights reserved.