Sharif Digital Repository

Abstract In this study, adsorption of the CO2 and N2 gases on the MIL-53(Al) and its hybrid composite with the graphene nano-plates (GNP), MIL-53(Al)/GNP, adsorbents were investigated. These materials were synthesized using the solvothermal reaction method. The prepared samples were characterized by means of the powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), N2 adsorption-desorption isotherms (BET-BJH surface area measurement) and Fourier transfer infrared (FT-IR) spectroscopy methods as well as; thermogravimetric analysis (TGA). Adsorption equilibrium of the CO2 and N2 on the sorbents were... 

La0.3Sr0.7FeO3-δ (LSF) perovskite was prepared according to two methods: (1) applying new phenolic derivative of serine amino acid (L) as chelating agent, and (2) in absence of L as ligand-free perovskite (LFP). The newly prepared aminophenolic ligand L was fully characterized by 1H and 13C NMR, IR as well as elemental analysis while the LSF perovskite samples were characterized using the IR spectra, powder x-ray diffraction (PXRD) patterns, and SEM micrographs. The PXRD pattern obtained for the perovskite prepared by L (PPP) indicated on the presence of pure perovskite phase. The hydrogen permeation through PPP and LFP membranes with thickness of 1.0mm were measured as a function of... 

Multi-layer ceramic membranes were prepared and used for hydrogen separation at high operating temperatures. The membranes were formed by depositing nano-scale, dense silica layers with a thickness of 80-90 nm on top of porous alumina substrates by atmospheric CVD method. The substrates were prepared by dipping macroporous α-alumina supports with three size-controlled boehmite solutions to obtain a graded structure. Permeation tests were performed at 800°C for single gases of H2, N2, CH4, and CO2. Hydrogen selectivity values of 100, 350, and 780 were obtained as the ratio of H2 permeation flux over CH4, N2, and CO2, respectively. This is an abstract of a paper presented at the CHISA 2012 -... 

A hydrogen-selective nano-composite ceramic membrane was prepared by depositing a dense layer composed of SiO2 and Al2O 3 on top of a graded multilayer substrate using co-current chemical vapor deposition (CVD) method. The multilayer substrate was made by dip-coating a macroporous α-alumina tubular support by a series of boehmite solutions to get a graded structure. Using DLS analysis, it was concluded that decreasing hydrolysis time and increasing acid concentration lead to smaller particle size of boehmite sols. XRD analysis was carried out to investigate the structure of intermediate layer and an optimized calcination temperature of 973 K was obtained. SEM images indicated the formation... 

The BaCe0.9Y0.1O3-δ (BCY) perovskite membrane was successfully synthesized by liquid citrate method. The phase structure of the powder was characterized by X-ray diffraction (XRD). Scanning electron microscopy (SEM) was used to characterize microstructures of the membrane sintered under various conditions. Sintering temperatures and dwell time during sintering influence the final microstructure of the ceramic. Results showed that increasing sintering temperature resulted in a dense membrane with clear grains. An increase of dwell time was favorable to produce membranes with larger grains in the sintered ceramics. A density of 5.87 g/cm3 was reached for the membrane after sintering at 1200 °C... 

Hydrogen permeation through ACe0.9Y0.1O3-δ (A = Sr, Ba, La, and BaSr) perovskite-type membranes was studied at high temperatures. X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to characterize phase structure and phase stability of the membrane. The XRD results showed the formation of a single phase of perovskite structure with configuration orthorhombic for BCY and BSCY membranes. Based on the TGA results, it was found that the phase stability increases in the order of LCY < SCY < BCY < BSCY. The microstructure examinations of the synthesized membranes studied by scanning electron microscopy (SEM) showed the formation of a dense-like... 

A catalytic membrane reactor was synthesized by coating a 4-5 micron thick Ni/γ-Al2O3 layer on top of a hydrogen selective SiO2/Al2O3 composite membrane using a sol-gel method. Mercury intrusion and BET analysis indicated a uniform size distribution with an average pore size of 285 nm and average surface area of 279 m2 g-1. Single-component permeation tests were carried out for H2, CH4 and CO2 in the temperature range of 650-800 °C and the results showed the same permeance and selectivity values for hydrogen as the composite membrane without a catalytic layer. Performance of the catalytic membrane was evaluated by using as a membrane reactor for the methane steam reforming reaction with a... 

This paper derives an estimated function made by simple Neural Network to find initial state of optimization parameters. It changes a system of differential equations with boundary values to a system of equations with initial values. So a lot of time would be saved to solve it. As a result, the system with differential equations will reach the desired final state. Copyright © 2006 by ASME  

A novel injectable in situ gelling thermosensitive chitosan-block-poly(ethylene glycol) formulation was synthesized for drug delivery applications. Block copolymerization of monomethoxy-poly(ethylene glycol) onto chitosan using potassium persulfate as an initiator was carried under a nitrogen atmosphere in aqueous solution. The effects of potassium persulfate and poly(ethylene glycol) concentrations, reaction time and reaction temperature on block polymerization were studied by determining the yield of reaction (%Y), polymerization efficiency (%E) and add-on percentage (%Add-on). Keeping the other conditions constant, the optimum reaction conditions were found to be initiator = 0.01 M,... 

A thermosensitive copolymer was synthesized by graft copolymerization of poly(lactide-co-glycolide) (PLGA) copolymers onto the surface of chitosan membranes. Acryloyl chloride was used as a coupling reagent for the covalent attachment of PLGA to the chitosan membranes. FTIR spectroscopy and DSC analysis were used to characterize the resulting graft copolymer. Thermosensitive swelling behaviors of the copolymer were investigated as well. The membranes exhibited reversible swelling-shrinking behavior; higher swelling ratios were obtained observed at higher temperatures. Drug permeation studies were carried out using vancomycin hydrochloride and betamethasone sodium phosphate as the model... 

A novel thermosensitive hydrogel was synthesized by block copolymerization of monomethoxy poly(ethylene glycol) macromere (PEG) onto chitosan backbone, using potassium per sulfate as a free radical initiator. This block copolymer exhibits a thermoreversible transition from an injectable solution at low temperature to a gel at body temperature. Synthesized copolymers were characterized using FT-IR, 1H NMR, 13C NMR, and DSC techniques. Solubility test was performed to compare water and organo-solubility of chitosan before and after copolymerization. Sol-gel transition behavior was investigated using the vial inversion method and viscosity measurements. The gelation behavior makes the... 

It is known that the thermomechanical processing is one of the most important techniques for improving quality and mechanical properties of microalloyed steels. In this paper, the main parameters of hot forging (preheat temperature, strain and post-forging cooling rate) on the primary austenite grain size of vanadium microalloyed steel (30MSV6) were studied. From this investigation, it was found that increasing preheat temperature from 1150 °C to 1300 °C will result in a decrease in grain size number. Furthermore, it has shown that as the strain increases, the austenite grain size number increases, as is evident for the two cooling rates of 2.5 °C/s and 1.5 °C/s for primary austenite.... 

The segmental translator linear switched reluctance motor (STLSRM) is a special type of linear switched reluctance motor (LSRM) that has more output power than its conventional type. Therefore, it can be a good choice for certain applications. Heat is one of the factors limiting the output in machines. Therefore, predicting the thermal distribution of machine is as important as the magnetic design. A comprehensive thermal model is presented based on the lumped parameter approach for STLSRM, which predicts temperature distribution in different parts of this motor, including slot winding, end-winding, stator pole, stator yoke, and the moving part. Considering that the proposed thermal model...