Search for: glass
Total 393 records
Glass-ceramics for cancer treatment: So close, or yet so far?, Article Acta Biomaterialia ; 2018 ; 17427061 (ISSN) ; Pakzad, Y ; Banijamali, S ; Kargozar, S ; Vitale Brovarone, C ; Yazdanpanah, A ; Bretcanu, O ; Ramedani, A ; Vernè, E ; Mozafari, M ; Sharif University of Technology
After years of research on the ability of glass-ceramics in bone regeneration, this family of biomaterials has shown revolutionary potentials in a couple of emerging applications such as cancer treatment. Although glass-ceramics have not yet reached their actual potential in cancer therapy, the relevant research activity is significantly growing in this field. It has been projected that this idea and the advent of magnetic bioactive glass-ceramics and mesoporous bioactive glasses could result in major future developments in the field of cancer. Undoubtedly, this strategy needs further developments to better answer the critical questions essential for clinical usage. This review aims to...
Synthesis & Properties of Nd-doped Glass-ceramics in the SiO2-CaO-MgO System from Sol-gel Method Used as Solid Lasers
Sharif University of Technology
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...
Influence of NaF on crystallization and machinability of mica glass ceramics, Article Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry ; Volume 42, Issue 7 , May , 2012 , Pages 958-964 ; 15533174 (ISSN) ; Nemati, A ; Hamnabard, Z ; Baghshahi, S ; Golikand, A. N ; Sharif University of Technology
Effect of NaF on crystallization kinetics, microstructure, and mechanical properties of mica glass ceramics were investigated by the differential thermal analysis (DTA), X-ray diffractometry (XRD), scanning electron microscopy (SEM), and microhardness tests. Non-isothermal DTA experiments showed that the crystallization activation energies of base glasses are changed in the range of 235-246 KJ/mol, while the crystallization activation energies of samples with addition of NaF are changed in the range of 263-367 KJ/mol. The increase of crystallization temperature is helpful for the increase of aspect ratio, and the microstructure of the glass ceramics becomes interconnected, which contributes...
Crystallization behavior of mica glass-ceramics with nanophase structure, Article Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry ; Volume 42, Issue 3 , 2012 , Pages 420-423 ; 15533174 (ISSN) ; Nemati, A ; Sharif University of Technology
The influence of Zr 2 on the crystallization behavior, microstructure, and machinability of SiO 2-Al 2O 3-MgO-K 2O-B 2O 3-F glasses was investigated. The crystallization of the glass-ceramic was markedly affected by addition of ZrO 2. These glasses crystallize more rapidly. The number of mica crystals increases, whereas the size of the mica crystals decreases drastically. Machining of these glass-ceramics was found to be good, as confirmed by a drilling test using conventional steel tools. Such mechanical properties are attributable to the microstructure of these glass-ceramics. Very fine crystals are homogeneously distributed in glass matrix
Utilization of DTA in the determination of a crystallization mechanism in transparent glass-ceramics with a nanocrystalline structure, Article Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry ; Volume 41, Issue 5 , 2011 , Pages 561-570 ; 15533174 (ISSN) ; Nemati, A ; Golikand, A. N ; Hamnabard, Z ; Baghshahi, S ; Sharif University of Technology
Non-isothermal differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to study the nucleation and crystallization behavior of mica glass-ceramics with LiF as nucleating agent. The models enabled establishing the kinetic parameters for crystal growth of individual phases. The activation energies for crystal growth were found to be in the range of 161-301 KJ/mol, 416-424 KJ/mol, and 583-1011 KJ/mol for base glasses, samples with substitution of Li2O for K2O and samples with addition of LiF, respectively. Formation of transparent glass-ceramics from studied glass-samples has been investigated. Transparency is assumed to occur in the...
Physical properties and applications of clay nanofiller/epoxy nanocomposites, Article Physical Properties and Applications of Polymer Nanocomposites ; 2010 , Pages 743-772 ; 9781845696726 (ISBN) ; Bagheri, R ; Sharif University of Technology
The physical properties including glass transition temperature and permeability behavior of clay-filled epoxies are reviewed in this chapter. There is no consensus in the literature on how nanoclay affects the α-relaxation temperature in epoxy systems. This perhaps rises from the complexity of nanoclay morphology in polymeric resins and the interphase properties since morphology of nanoclay and interphase characteristics are two key parameters to control the glass transition process in epoxy nanocomposites. In addition, the possible existence of several α-transitions in montmorillonite-filled epoxies due to the existence of several relaxation domains may account for the controversial...
Discovery of novel quaternary bulk metallic glasses using a developed correlation-based neural network approach, Article Computational Materials Science ; Volume 186 , 2021 ; 09270256 (ISSN) ; Gholamipour, R ; Samavatian, V ; Sharif University of Technology
Elsevier B.V 2021
The immense space of composition-processing parameters leads to numerous trial-and-error experimental works for engineering of novel bulk metallic glasses (BMGs). To tackle this challenging problem, it is required to consider specific guidelines which are able to restrict the productive alloying compositions. In this work, a correlation-based neural network (CBNN) approach was developed, based on a dataset of 7950 alloying compositions, to design potential new MGs through prediction of casting ability, reduced glass transition (Trg) and critical thickness (Dmax). This approach involves individual and mutual characteristics of contributory factors to improve the prediction accuracy. To...
Simulation of windscreen bending using viscoplastic formulation, Article Journal of Materials Processing Technology ; Volume 170, Issue 1-2 , 2005 , Pages 298-303 ; 09240136 (ISSN) ; Rad, M ; Shahhosseini, M. R ; Shahhosseini, M. H ; Sharif University of Technology
Soda-lime glass material has been widely used for automobile windscreens. Two commercial finite element programs have been evaluated for simulation of the creep forming process using isotropic viscoplastic behavior assumption for soda-lime glass. This was done by selecting one of the programs and using it in connection with an optimization program for controlling the glass surface temperature, to examine the effect of considering thermal stresses and temperature variations along the surface of glass sheet for obtaining desired geometrical shape. The results show that the thermal stress effect must be considered for achieving more accurate simulation of glass creep forming process. Also...
Effect of temperature on the fracture surface morphology of Ti- and Zr-based bulk metallic glasses: exploring correlation between morphology and plasticity, Article Journal of Materials Science ; Volume 53, Issue 14 , July , 2018 , Pages 10372-10382 ; 00222461 (ISSN) ; Tavakoli, R ; Aashuri, H ; Sharif University of Technology
Springer New York LLC 2018
According to previous studies on the fracture surface morphologies of bulk metallic glasses, the stable crack growth region width and vein pattern size increase with the plasticity at room temperature. In the present work, the fracture surface morphologies of Ti- and Zr-based bulk metallic glasses bent over a wide temperature range (0.1–0.8 glass transition temperature) are systematically analyzed. According to our finding, the stable crack growth region width increases while the vein pattern size decreases as the ductility improves by varying temperature. This observation is in contrast to the common thought that the ductility is proportional to the stable crack growth region width and vein...
synergistic toughening in ternary silica/hollow glass spheres/epoxy nanocomposites, Article Polymer - Plastics Technology and Engineering ; Volume 54, Issue 6 , 2015 , Pages 581-593 ; 03602559 (ISSN) ; Bagheri, R ; Kouchakzadeh, M. A ; Abadyan, M ; Sharif University of Technology
Taylor and Francis Inc 2015
Herein, the fracture toughness of ternary epoxy systems containing nanosilica and hollow glass microspheres (HGMS) is investigated. The experimental measurements reveal synergistic fracture toughness in some hybrid compositions: The incorporation of 10 phr of HGMS and nanosilica alone modify the fracture toughness of epoxy by 39% and 91%, respectively. However, use of 10 phr hybrid modifier can enhance the fracture toughness of the resin up to 120%. Observations reveal different toughening mechanisms for the blends i.e., plastic deformation for silica nanoparticles and crack bifurcation for HGMS. Both of these toughening mechanisms additively contribute to the synergism in ternary epoxies
Stochastic qualifier of gel and glass transitions in laponite suspensions, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 81, Issue 6 , Jun , 2010 ; 15393755 (ISSN) ; Jabbari Farouji, S ; Movahed, M. S ; Jafari, G. R ; Rahimi Tabar, M. R ; Sharif University of Technology
The existence of the important similarities between gelation and glass transition makes it hard to distinguish between the two types of nonergodic states experimentally. Here, we report on a stochastic analysis of the scattered light intensity through a colloidal particles suspension during the gel and glass formation. In this analysis, we exploit the methods developed for complex hierarchical systems, such as turbulence. Using the multiplicative log-normal cascade models, we provide a criterion to distinguish gels from glasses
Molecular dynamics simulation of melting, solidification and remelting processes of aluminum [electronic resource], Article Iranian Journal of Science and Technology ( IJST): Transactions of Mechanical Engineering ; 2012, Vol.36, No. M1, P.13-23 ; Simchi, A. (Abdolreza) ; Aashuri, H ; Sharif University of Technology
A molecular dynamics simulation study has been performed to investigate the solidification and remelting of aluminum using Sutton - Chen many body potential. Different numbers of atoms from 108 to 2048 atoms were considered to find an adequate size for the system. Three different cooling and heating rates, i.e. 1 0 12 K/s, 10 13 K/s and 10 14 K/s, were used. The structure of the system was examined using radial distribution function. The melting and crystallization temperatures of aluminum were evaluated by calculating the variation of heat capacity during the phase t ransformation. Additionally, Wendt – Abraham parameters were calculated to determine the glass transition temperature. It is...
Effect of particle size on the in vitro bioactivity, hydrophilicity and mechanical properties of bioactive glass-reinforced polycaprolactone composites [electronic resource], Article Journal of Materials Science and Engineering: C ; 10 October 2011, Volume 31, Issue 7, Pages 1526–1533 ; Bagheri, R ; Vossoughi, M ; Simchi, A. (Abdolreza) ; Sharif University of Technology
Polycaprolactone (PCL) composite films containing 5 wt.% bioactive glass (BG) particles of different sizes (6 μm, 250 nm, < 100 nm) were prepared by solvent casting methods. The ultra-fine BG particles were prepared by high-energy mechanical milling of commercial 45S5 Bioglass® particles. The characteristics of bioactive glass particles were studied by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray diffraction (XRD) methods. In vitro bioactivity of the PCL/BG composite films was evaluated through immersion in the simulated body fluid (SBF). The films were analyzed by FE-SEM, energy dispersive...
Micro-model experimental study of fracture geometrical effect on breakthrough time in miscible displacement process, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 30, Issue 3 , 2011 , Pages 1-7 ; 10219986 (ISSN) ; Rashtchian, D ; Shadizadeh, S. R ; Sharif University of Technology
The miscible displacement process appears to be an increasingly feasible method for the extraction of oil from depleted reservoirs. However, there is a lack of fundamental understanding of how fracture geometrical characteristics impact the oil recovery efficiency in this type of enhanced oil recovery technique. In this work, a series of experimental tests were conducted whereby the n-Heptane as a solvent displaced n-Decane in the glass micro-models having different fracture geometries. It has been observed that the breakthrough time is decreased with increasing the fractures' length. In contrast, breakthrough time is increased when increasing the fractures orientation angle related to flow...
Molecular dynamics study of structural formation in Cu50-Zr50 bulk metallic glass, Article Journal of Non-Crystalline Solids ; 2015 ; 00223093 (ISSN) ; Tavakoli, R ; Aashuri, H ; Sharif University of Technology
In this work, the evolution of the local structure in Cu50-Zr50 bulk metallic glass during glass formation was studied by molecular dynamics simulation. The pair distribution function and Voronoi analysis were adopted to characterize local structures in this alloy. The stability of icosahedral clusters and the role of other local clusters in the formation of icosahedra were evaluated. It was found that the (0,2,8,2) polyhedron is not only the dominant cluster in this alloy, but also the most prone cluster to convert into an icosahedron in the course of cooling. Moreover, it acts as an intermediate state during the icosahedron formation. The onset of stability of icosahedra emerges at the...
Molecular dynamics study of structural formation in Cu50–Zr50 bulk metallic glass, Article Journal of Non-Crystalline Solids ; Volume 432 , 2016 , Pages 334-341 ; 00223093 (ISSN) ; Tavakoli, R ; Aashuri, H ; Sharif University of Technology
Elsevier B. V 2016
In this work, the evolution of the local structure in Cu50–Zr50 bulk metallic glass during glass formation was studied by molecular dynamics simulation. The pair distribution function and Voronoi analysis were adopted to characterize local structures in this alloy. The stability of icosahedral clusters and the role of other local clusters in the formation of icosahedra were evaluated. It was found that the (0,2,8,2) polyhedron is not only the dominant cluster in this alloy, but also the most prone cluster to convert into an icosahedron in the course of cooling. Moreover, it acts as an intermediate state during the icosahedron formation. The onset of stability of icosahedra emerges at the...
Halogen-lithium exchange reaction using an integrated glass microfluidic device: an optimized synthetic approach, Article Organic Process Research and Development ; Volume 21, Issue 3 , 2017 , Pages 292-303 ; 10836160 (ISSN) ; Mohammadi, A ; Sharif University of Technology
American Chemical Society 2017
A telescoped approach was developed for the efficient synthesis of methoxybenzene through the generation of an unstable intermediate reagent, based on the Br-Li exchange reaction of p-bromoanisole and n-BuLi, followed by its reaction with water. In the first stage, p-methoxyphenyllithium was synthesized and consumed immediately in the second stage. For this purpose, an integrated glass microfluidic device was fabricated using laser ablation followed by the thermal fusion bonding method. The impact of various parameters, including solvent, reaction time, molar ratio, concentration of reagents, and flow rates were investigated to achieve the highest yield of the desired product, leading to an...
Holographic diffusers: application for indoor infrared communications, Article International Journal of Wireless Information Networks ; Volume 4, Issue 4 , 10-01 , 1997 , pp 259-274 ; 1572-8129 ; Simova, E ; Kavehrad, M ; Sharif University of Technology
Diffused infrared transmission is one of thepreferred techniques used in indoor wirelesscommunications. Tolerance to shadowing and a lack ofalignment requirements are among the many advantagesoffered by this technique compared to the line-of-sighttechniques. However, it has its disadvantages, namelyhigh path loss and multipath dispersion. The limitationimposed by eye-safety requirements restricts the transmitted power. Therefore, efficient useof transmitted optical power is the key for practicalbroadband infrared systems. In this paper, we report onusing a holographic diffuser for shaping of infrared radiation pattern in an indoorinfrared transmission system. The holographic diffusershave...
The effect of elevated temperatures on the compressive section capacity of pultruded GFRP profiles, Article Construction and Building Materials ; Volume 249 , July , 2020 ; Najafabadi, E. P ; Bazli, M ; Vatani Oskouei, A ; Zhao, X. L ; Sharif University of Technology
Elsevier Ltd 2020
The compressive performance of glass fiber reinforced polymer (GFRP) profiles subjected to elevated temperature was investigated through a large number of (3 0 0) tests. The effects of profile cross-sectional area, slenderness, and temperature on the behavior of the GFRP profiles at temperatures ranging from 25 to 400 °C were determined. It was observed that the compressive strength of the GFRP profiles has been decreased by half as the temperature exceeded 90 °C, i.e., close to the glass transition temperature of the matrix. The temperature and ratio of cross-sectional area to external perimeter were determined as two major parameters affecting section capacity. © 2020 Elsevier Ltd
Porous slow release silicate-phosphate glasses synthesized by polymer-derived ceramics method appropriate for plants nourishment, Article Iranian Journal of Materials Science and Engineering ; Volume 18, Issue 1 , 2021 , Pages 80-90 ; 17350808 (ISSN) ; Abdollahi, S ; Khalilifard, R ; Madaah Hosseini, H. R ; Sharif University of Technology
Iran University of Science and Technology 2021
As an alternative to conventional fertilizers, e.g. NPK (the Nitrogen-Phosphorous-Potassium-containing chemical fertilizers) which release their nutrients in a short time glass fertilizers are ideal as they release macro-and micronutrients for crops and plant nourishment more gradually. Also, despite conventional ones, they have no ground-water pollution. In the present study, glass fertilizers were synthesized via polymer-derived ceramics (PDC) method. Despite the melt-casting procedure, PDC needs lower temperatures in heat treatment. The precursors consist of poly-siloxane and active fillers. Thus, thanks to gaseous release during heat treatment of the present active fillers, i.e. Ca(OH)2,...