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Synthesis & Properties of Nd-doped Glass-ceramics in the SiO2-CaO-MgO System from Sol-gel Method Used as Solid Lasers
,
M.Sc. Thesis
Sharif University of Technology
;
Hamnabard, Zohreh
(Supervisor)
;
Nemati, Ali
(Supervisor)
Abstract
In this study, SiO2-CaO-MgO galsses and glass-ceramic powder doped with Nd3+ were synthesized with sol-gel method. Tetraethylorthosilicate (TEOS), Ca(NO3)2.4H2O, Mg(NO3)2.6H2O, Nd(NO3)3.6H2O, ethanol, distilled water, and HNO3 were used as starting materials. The synthesized powder’s properties were examined with STA, XRD, DRS, PL, FTIR and SEM analysis. From XRD patterns of glass samples, the role of dopant was introduced as intermediate oxide in glass matrix. The XRD patterns of glass-ceramic samples indicated that the bredigite and akermanite crystals were formed in glass matrix. The band gap energy of samples were calculated from DRS analysis and were seen with increasing the dopant...
Simulation of elasto-plastic deformations in composites by flow rules
, Article Indian Journal of Science and Technology ; Vol. 7, issue. 2 , 2014 , pp. 180-184 ; ISSN: 09746846 ; Fazaeli, D ; Daneshmand, S ; Shafaghatian, N ; Sharif University of Technology
Abstract
In this paper, a novel model is proposed to predict stress behavior in the fibrous polymer composites under an applied tensile axial loading. Tangential stress is obtained by simulating between polymeric matrix flow (polyester) and fluid flow. In the other words, creep behavior of the petrochemical material or polymeric resin (matrix) is modeled using fluid flow theory. Furthermore, behavior of the shear stress is predicted by suitable mathematical functions. Finally, important relation is extracted by combining the solid and fluid mechanics formulations
Structural aspects and the conduction mechanism of Ln(Ba 2-xPrx)Cu3O7+δ (Ln = Tm, Lu)
, Article Physica Status Solidi (B) Basic Research ; Volume 244, Issue 9 , 2007 , Pages 3211-3222 ; 03701972 (ISSN) ; Akhavan, M ; Sharif University of Technology
2007
Abstract
TmBa2_xPrxCu3O7+δ and LuBa2_xPrxCu3O7+δ samples with 0.0 < x ≤ 1.0 have been prepared by a solid-state reaction technique. The occurrence of the orthorhombic to tetragonal phase transition, increasing of oxygen content with the increase of Pr doping, and the existence of solubility limit in both systems confirm the correct substitution of Pr at Ba sites. The solubility limit for Pr in the Lu-based samples is less than 0.7, which is less than x = 0.90 for the Tm-based samples. The Tc depression versus doping content in both systems shows that depression of superconductivity by Pr at Ba sites is mostly due to the hole-filling/localization effects. Also, in the Tm-based system, the...
Oxidation of 1,4-dihydropyridines under mild and heterogeneous conditions using solid acids
, Article Journal of the Iranian Chemical Society ; Volume 3, Issue 1 , 2006 , Pages 73-80 ; 1735207X (ISSN) ; Bagherzadeh, M ; Niknam, K ; Shirini, F ; Mohammadpoor Baltork, I ; Ghorbani Choghamarani, A ; Baghbanzadeh, M ; Sharif University of Technology
Iranian Chemical Society
2006
Abstract
A combination of solid acids, including Oxone®, HIO3, H 5IO6, and polystyrenesulfonic acid and sodium nitrite, in the presence of wet SiO2 were used as an effective oxidizing agents for the oxidation of dihydropyridines to their corresponding pyridine derivatives under mild and heterogeneous conditions in good to excellent yields
Aminoalkylation with aldehydes mediated by solid lithium perchlorate
, Article Monatshefte fur Chemie ; Volume 135, Issue 3 , 2004 , Pages 309-312 ; 00269247 (ISSN) ; Nazari, M ; Sharif University of Technology
2004
Abstract
The solid LiClO4-mediated one-pot reaction of aldehydes with secondary amines and C nucleophiles afforded the corresponding aminoalkylation products in high yields. Unlike the previous reported procedure, the aminoalkylation of aldehyde was achieved in the presence of only 0.5 equivalents of solid lithium perchlorate in dichloromethane as the solvent with good to high yields at room temperature. © Springer-Verlag 2003
Solvent-free rapid microwave-assisted β-elimination of sulfoxides
, Article Sulfur Letters ; Volume 24, Issue 6 , 2001 , Pages 269-273 ; 02786117 (ISSN) ; Djamshidi, H ; Sharif University of Technology
2001
Abstract
Basic silica gel (NaOH/SiO2) was found to be a very efficient media for the dehydrosulfenylation of sulfoxides in solvent-free condition under microwave irradiation
Toughening epoxy resins with solid acrylonitrile-butadiene rubber
, Article Polymer International ; Volume 49, Issue 2 , 2000 , Pages 163-169 ; 09598103 (ISSN) ; Mehrabzadeh, M ; Parvary, M ; Sharif University of Technology
2000
Abstract
The feasibility of using solid acrylonitrile-butadiene rubbers (NBR) with 19 and 33% w/w acrylonitrile to toughen diglycidyl ether of bisphenol A (DGEBA) epoxy resins has been investigated. Thermal analysis experiments revealed a two-phase morphology of these rubber-modified epoxies. However, the higher content of acrylonitrile in the rubber caused better compatibility between NBR and the epoxy resin. The rubber with 33% acrylonitrile was found to be an effective toughening agent for DGEBA epoxy resins. Fracture surface studies and also the high tensile strength of crosslinked high molecular weight NBR suggest that the toughening effect should arise from rubber bridging and tearing...
Microstructural investigation of semisolid aluminum a356 alloy prepared by the combination of electromagnetic stirring and gas induction
, Article 15th International conference on Semi-Solid Processing of Alloys and Composites, S2P 2018, 22 October 2018 through 24 October 2018 ; Volume 285 SSP , 2019 , Pages 290-295 ; 16629779 (ISSN); 9783035713732 (ISBN) ; Yekani, F ; Aashuri, H ; Sharif University of Technology
Trans Tech Publications Ltd
2019
Abstract
A three phase electromagnetic stirrer was used to agitate aluminum A356 slurry and a dry and oxygen free argon gas was introduced in to the slurry by a porous graphite core at a same time. The prepared semi-solid slurry was then transferred into a metallic mold and was compacted by a drop weight. Results demonstrated a favorable increase in shape factor, decrease in aspect ratio and average diameter size at different intensities of stirring. The intensity of stirring was changed by altering the current passed through the magnetic coil and also bubbling intensity via the porous graphite diffuser. Different time intervals for electromagnetic stirring and gas induction were applied. Agitating...
Transient conduction prediction in nozzle assembly of solid rocket motors
, Article 45th AIAA Aerospace Sciences Meeting 2007, Reno, NV, 8 January 2007 through 11 January 2007 ; Volume 4 , 2007 , Pages 2333-2337 ; 1563478900 (ISBN); 9781563478901 (ISBN) ; Tahsini, A. M ; Sharif University of Technology
2007
Abstract
Transient heat-up of a solid propellant rocket structure during motor burning time is studied, numerically. The solid phase energy equation coupled with unsteady compressible flow equations are used in this simulation. The flow-field equations are discretized and solved using upwind Roe's scheme. The results show that heat transfer from the gas phase boundaries has negligible effect on internal ballistics behavior. On the other hand, the results are suitable for a thermal stresses analysis in the chamber case and are consequently valuable from structural design viewpoints
Modeling of semi-solid A356 alloy under upsetting process
, Article Solid State Phenomena ; Volume 116-117 , 2006 , Pages 622-625 ; 10120394 (ISSN) ; Aashuri, H ; Sharif University of Technology
Trans Tech Publications Ltd
2006
Abstract
The flow behavior of a semi-solid A356 alloy at high solid fraction was studied. The mushy zone was considered as an effective two-phase, so that the solid continuum can be compressible porous media, and the liquid phase interaction with the solid skeleton was of Darcy type. The semi-solid flow through the upsetting test was modeled in ABAQUS finite element method software. The Gurson yield criterion has been developed for the modeling process of the flow behavior of solid porous medium. Specimens were globulized by a thermomechanical process and then were tested for various percentages of upsetting. The distribution of solid fraction along the radius of the specimens at different height...
Microwave-induced Cannizzaro reaction over neutral γ-alumina as a polymeric catalyst [electronic resource]
, Article Reactive and Functional Polymers ; 01/2002; 51(1):49-53 ; Soleimanzadeh, B ; Marandi, G. B
Abstract
γ-Alumina is used to catalyze the Cannizzaro reaction in the absence of any base under microwave irradiation in high yields. In the case of terephthalaldehyde the reaction is carried out with high selectivity
Magnetic and electric field assisted electrospun polyamide nanofibers for on-line μ-solid phase extraction and HPLC
, Article RSC Advances ; Vol. 4, Issue. 94 , 2014 , pp. 52590-52597 ; ISSN: 20462069 ; Piri-Moghadam, H ; Rastegar, S ; Sharif University of Technology
Abstract
The effects of applied magnetic and electric fields on electrospinning were investigated to produce more efficient nanofibers. Considering the previous extensive studies, polyamide nanofibers were prepared by a conventional approach and under auxiliary electric and magnetic fields. The first sorbent was synthesized by electrospinning of a solution of 18% polyamide in formic acid. The second and third types of polyamide were prepared similarly while the electrospinning processes were assisted by an electric and a magnetic field. The third type of polyamide contained a magnetic ionic liquid (MIL) to induce sufficient magnetic susceptibility in the polymeric solution. The SEM images revealed...
Simultaneous determination of theophylline, theobromine and caffeine in different tea beverages by graphene-oxide based ultrasonic-assisted dispersive micro solid-phase extraction combined with HPLC-UV
, Article RSC Advances ; Vol. 4, issue. 87 , 2014 , p. 47114-47120 ; Khosraviani, M ; Samadi, S ; Amini-Fazl, M. S ; Sharif University of Technology
Abstract
A simple ultrasound-assisted dispersive micro-solid phase extraction method based on graphene-oxide (GO) nanosorbents (UAD-μ-SPE), followed by high performance liquid chromatography-ultraviolet detection (HPLC-UV) was developed for the simultaneous determination of theophylline, theobromine and caffeine in different infusion tea samples. GO was synthesized by Hummers method and characterized with field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. The GO sorbent was dispersed in the sample solution with the assistance of ultrasound to enhance adsorption and desorption performance and rates. The main parameters...
Simulating fluid-solid interaction problems using an immersed boundary-SPH method
, Article Particle-Based Methods II - Fundamentals and Applications, 26 October 2011 through 28 October 2011 ; Octobe , 2011 , Pages 954-965 ; 9788489925670 (ISBN) ; Fatehi, R ; Manzari, M. T ; Sharif University of Technology
Abstract
In this work, the Immersed Boundary Method (IBM) is adapted and implemented in the context of Smoothed Particle Hydrodynamics (SPH) method to study moving solid bodies in an incompressible fluid flow. The proposed computational algorithm is verified by solving a number of benchmark particulate flow problems. The results are also compared with those obtained using the same SPH scheme along with a direct solid boundary imposition technique
Two-Step Physical Deposition of a Compact CuI Hole-Transport Layer and the Formation of an Interfacial Species in Perovskite Solar Cells
, Article ChemSusChem ; 2016 , Pages 1929-1937 ; 18645631 (ISSN) ; Nejand, B. A ; Moshaii, A ; Mohammadian, N ; Alizadeh, A. H ; Mohammadpour, R ; Ahmadi, V ; Alizadeh, A ; Sharif University of Technology
Wiley-VCH Verlag
2016
Abstract
A simple and practical approach is introduced for the deposition of CuI as an inexpensive inorganic hole-transport material (HTM) for the fabrication of low cost perovskite solar cells (PSCs) by gas–solid phase transformation of Cu to CuI. The method provides a uniform and well-controlled CuI layer with large grains and good compactness that prevents the direct connection between the contact electrodes. Solar cells prepared with CuI as the HTM with Au electrodes displays an exceptionally high short-circuit current density of 32 mA cm−2, owing to an interfacial species formed between the perovskite and the Cu resulting in a long wavelength contribution to the incident photon-to-electron...
Tilted-Lorentz symmetry
, Article Iranian Journal of Physics Research ; Volume 19, Issue 4 , Winter , 2020 , Pages 831-834 ; Sharif University of Technology
Isfahan University of Technology
2020
Abstract
Dirac cone can be tilted in condensed matter setting. As a result of tilt, the Lorentz symmetry is reduced to what we call tilted-Lorentz symmetry. In this paper, we derive the tilted-Lorentz transformations that leave a world with tilted Dirac cone invariant. © 2020, Isfahan University of Technology. All rights reserved
Markov analysis and Kramers-Moyal expansion of the ballistic deposition and restricted solid-on-solid models
, Article Journal of Statistical Mechanics: Theory and Experiment ; Volume 2008, Issue 2 , 2008 ; 17425468 (ISSN) ; Jafari, G. R ; Rahimi Tabar, M. R ; Sharif University of Technology
2008
Abstract
It is well known that the ballistic deposition and the restricted solid-on-solid models belong to the same universality class, having the same roughness and growth exponents. In this paper, we determine some new statistical properties of the two models, such as the Kramers-Moyal coefficients and the Markov length scale, and show them to be distinct for the two models. © 2008 IOP Publishing Ltd
Reactive milling synthesis of nanocrystalline Al-Cu/Al2O3 nanocomposite
, Article Materials Science and Engineering A ; Volume 464, Issue 1-2 , 2007 , Pages 225-232 ; 09215093 (ISSN) ; Simchi, A ; Sharif University of Technology
2007
Abstract
Nanocrystalline Al-4 wt% Cu alloy reinforced with nanometric Al2O3 particles was synthesized by in situ reactive milling of Al and CuO powder mixture. X-ray diffraction (XRD), differential thermal analysis (DTA) and transmission electron microscopy (TEM) techniques were employed to study the mechanically induced solid state reaction between the blended powders. The mechanical milling stages were studied by scanning electron microscopy (SEM), bulk density measurement and laser particle size analyzer. It was shown that the reaction between Al and CuO occurs progressively as the mechanical milling continues, leading to formation of nanoscaled alumina particles. The grain refinement of the...
Applications of polymeric reagents in organic synthesis
, Article Monatshefte fur Chemie ; Volume 138, Issue 4 , 2007 , Pages 363-379 ; 00269247 (ISSN) ; Rahimi, A ; Pourjavadi, A ; Sharif University of Technology
2007
Abstract
Polymer supported reagents have found many applications in recent years. Scientists in research laboratories of agrochemical and pharmaceutical industries now routinely utilize these compounds to prepare ensembles of small organic molecules for screening. This review is aimed to highlight some of the most important applications of these promising materials in organic synthesis. Furthermore, an extensive listing of polymeric reagents that were recently used in organic synthesis is included. © Springer-Verlag 2007
Rapid and selective acetalization of aldehydes using anhydrous copper sulfate supported on silica gel (CuSO4/SiO2) under microwave irradiation in solvent-free conditions
, Article Letters in Organic Chemistry ; Volume 2, Issue 2 , 2005 , Pages 151-155 ; 15701786 (ISSN) ; Oskoui, A. A ; Boinee, H. Z ; Sharif University of Technology
2005
Abstract
CuSO4/SiO2 is found to be an efficient and selective medium for the acetalization of aldehydes in the presence of ketones in solvent-free conditions under microwave irradiation. © 2005 Bentham Science Publishers Ltd