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Phase-only femtosecond optical pulse shaping based on an all-dielectric polarization-insensitive metasurface
, Article Optics Express ; Volume 29, Issue 22 , 2021 , Pages 36900-36914 ; 10944087 (ISSN) ; Tehranian, A ; Salehi, J. A ; Sharif University of Technology
The Optical Society
2021
Abstract
Recently, metasurfaces capable of manipulating the amplitude and the phase of an incident wave in a broad frequency band have been employed for femtosecond optical pulse shaping purposes. In this study, we introduce a phase-only pulse shaper based on an all-dielectric CMOS-compatible polarization-insensitive metasurface, composed of Si nano cylinders sitting on a fused silica substrate. The required phase profile of the metasurface for desired waveforms are calculated using an iterative Fourier transform algorithm, and the performance of the pulse shaper metasurface in implementing the phase masks was assessed using full-wave simulations. Such approach for realizing a...
Phase-only femtosecond optical pulse shaping based on an all-dielectric polarization-insensitive metasurface
, Article Optics Express ; Volume 29, Issue 22 , 2021 , Pages 36900-36914 ; 10944087 (ISSN) ; Tehranian, A ; Salehi, J. A ; Sharif University of Technology
The Optical Society
2021
Abstract
Recently, metasurfaces capable of manipulating the amplitude and the phase of an incident wave in a broad frequency band have been employed for femtosecond optical pulse shaping purposes. In this study, we introduce a phase-only pulse shaper based on an all-dielectric CMOS-compatible polarization-insensitive metasurface, composed of Si nano cylinders sitting on a fused silica substrate. The required phase profile of the metasurface for desired waveforms are calculated using an iterative Fourier transform algorithm, and the performance of the pulse shaper metasurface in implementing the phase masks was assessed using full-wave simulations. Such approach for realizing a...
Immobilization of penicillin G acylase on non-porous ultrafine silica particles
, Article Scientia Iranica ; Volume 12, Issue 3 , 2005 , Pages 295-299 ; 10263098 (ISSN) ; Kheirolomoom, A ; Sharif University of Technology
Sharif University of Technology
2005
Abstract
In this paper, immobilization of penicillin G aclylase onto non-porous ultrafine silica particles has been studied. The amount of penicillin G acylase immobilized was increased by increasing the free enzyme concentration and, at 0.45 mg/ml concentration of the free enzyme, 80% of the enzyme was immobilized. The optimum pH for immobilization was found to be 7.0, close to the pl of the enzyme. Although immobilization of the enzyme on ultrafine silica particles with and without glutaraldehyde showed almost the same activities, the enzyme immobilized with glutaraldehyde retained its initial activity much longer during 40 cycle-repeated batches with a half life of 163.2 h. © Sharif University of...
Adsorption dynamics of surface-modified silica nanoparticles at solid-liquid interfaces
, Article Langmuir ; Volume 38, Issue 41 , 2022 , Pages 12421-12431 ; 07437463 (ISSN) ; Bastani, D ; Mohammadi, A ; Kordzadeh, A ; Sharif University of Technology
American Chemical Society
2022
Abstract
Understanding the adsorption dynamics of nanoparticles at solid-liquid interfaces is of paramount importance to engineer nanoparticles for a variety of applications. The nanoparticle surface chemistry is significant for controlling the adsorption dynamics. This study aimed to experimentally examine the adsorption of surface-modified round-shaped silica nanoparticles (with an average diameter of 12 nm), grafted with hydrophobic (propyl chains) and/or hydrophilic (polyethylene glycol chains) agents, at an aqueous solution-silica interface with spherical soda-lime glass beads (diameter of 3 mm) being used as adsorbents. While no measurable adsorption was observed for solely hydrophobic or...
Gold-based hybrid nanostructures: more than just a pretty face for combinational cancer therapy
, Article Biophysical Reviews ; Volume 14, Issue 1 , 2022 , Pages 317-326 ; 18672450 (ISSN) ; Bavi, O ; Zamani, M ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
The early diagnosis together with an efficient therapy of cancer is essential to treat cancer patients and to enhance their quality of life. The use of nanostructures, as a newer technology, has demonstrated proven benefits as efficient cancer theranostic agents in numerous recent studies. Having a tunable surface plasmon resonance, gold nanostructures have been the subject of many recent studies as excellent imaging and photothermal therapy agents. However, the potential cytotoxicity and weak stability of gold nanostructures necessitate further modifications using biocompatible materials for biological applications. Based on the composition of the final structure, these gold-based hybrid...
Studies of Ponceau 4R food colorant and zinc oxide nanoparticles containing it interactions with DNA and evaluation of their antimicrobial activity
, Article Journal of Food Processing and Preservation ; Volume 46, Issue 2 , 2022 ; 01458892 (ISSN) ; Shahabadi, N ; Mahmoudi Hashemi, M ; Meibodi, F. S ; Mirjafari, Z ; Sharif University of Technology
John Wiley and Sons Inc
2022
Abstract
The current study describes design and synthesis of silica-coated zinc oxide nanoparticles containing Ponceau 4R food colorant (named as ZnO@SiO2@APTMS/P4R). The interactions of Ponceau 4R and ZnO@SiO2@APTMS/P4R with calf thymus-DNA were investigated It should be noted that the competitive binding experiment revealed that both Ponceau 4R and ZnO@SiO2@APTMS/P4R could release Hoechst 33258. As inferred from the results the binding of the Ponceau 4R and ZnO@SiO2@APTMS/P4R with DNA were surface binding, mainly due to groove binding. Furthermore, antibacterial properties of ZnO, Ponceau 4R and ZnO@SiO2@APTMS/P4R samples against gram-positive bacteria and gram-negative bacteria were examined and...
Experimental Investigation of Mechanical Behavior of Structural Concrete with Combination of Waste Glass and Silica Fume
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Ali Reza (Supervisor)
Abstract
Concrete is the second most structural material in the world. So attention and promotion of the concrete mix design with respect to variable issues and requirements, is very important. On the other hand, these days environment and its pollution has become very popular discussion. Waste-glass which is produced by human products is one of the environmental pollutants. In this thesis it replaces some aggregate in concrete and it can reduce the level of this material in the world. Also we study effects of silica-fume as cement replacement and properties enhancer in our concrete mix design and see how it can ...
Synthesis of SiO2/Gd(OH)CO3/TiO2 Core/Shell Nanocomposite for Biological Applications
, M.Sc. Thesis Sharif University of Technology ; Hosseini, Madaah (Supervisor)
Abstract
Inthisresearch,silicananoparticleswere synthesized ymicroemulsionmethod. Thengadoliniumcarbonatewascoated onsilicananoparticles by depositiontechnique.After thatTiO2wascoatedbydeposition techniqueonsilica/gadolinium carbonatenanoparticles.The results of infrared spectroscopy (FT-IR) on silica/gadolinium carbonatesamples showed carbonate bonds. The results of X-ray diffraction (XRD) test on samples of silica/gadolinium carbonatethat had been calcined at 600 0C for 2 h, showed that silica and gadolinium carbonate phases are amorphous and with increasing calcination temperature, gadolinium oxide crystalline phase is formed. For TiO2 coatings process, the effect of TBOT concentration, the...
Synthesis of Mesoporous Silica-Magnetite Nanocopmposite for Biological Applications
, M.Sc. Thesis Sharif University of Technology ; Madaah Hosseini, Hamid Reza (Supervisor)
Abstract
During the most recent years, investigating novel nanomaterials based on porous strucures has become an interesting field of research. Among these kinds of materials, mesoporous silica has extensive applications in catalysis, absorbants and biomedical engineering. By combining specific surface characteristics of mesoporous silica with magnetic properties of iron oxide nanoparticles, new nanocomposites owing unique properties, can be obtained. In the present research, magnetic mesoporous nanocomposite has been synthesized. Iron oxide nanoparticles were produced through reduction of water solution containing Fe2+/Fe3+ ions, followed by hydrothermal treatment of precipitan. Then, iron oxide...
A Study on the Simultaneous Effects of the Nanosilica, Microsilica and the Water-cement Ratio on the Compressive Strength of Concrete
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
Nowadays, concrete is considered as one of the most important and useful engineering construction materials. Different concrete with diverse characteristics are used in various designs every day. One of the main considered parameters in concrete usage is its compressive strength. So far, many additives are used to increase the compressive strength of concrete most important of which are Nano-Silica and Micro-Silica. In addition, some of concrete characteristics such as water-to-cement ratio have significant effects on the concrete strength. Many experiments and investigations are conducted so far to study the effects of each of mentioned factors separately on the concrete strength. However...
Imprinting Technology in Tumor Marker Detection
, M.Sc. Thesis Sharif University of Technology ; Abdekhodaie, Mohammad Jafar (Supervisor)
Abstract
Tumor markers are substances that are naturally found in blood and other fluids in body, but in abnormal conditions such as cancer and metastasis, their level increase. The aim of researching about tumor markers is to find a way for discovering cancer only with a blood test and replace with the current methods such as ELISA, and any type of cancer can be detected by these tests. In this study, molecular imprinted polymers were synthesized with biomolecules. To do that, silica microparticles were used as solid base and after functionalizing their surface, a thin film of polymer was synthesized on them. To optimize the components concentrations and the polymer thickness on the silica surface,...
Immobilization of Pd Nanoparticles on Functionalized SBA-15 and a Robust Mesoporous Catalyst for Reduction and Oxidation Reactions and Synthesis of Tetrasubstituted Pyrroles Via Multicomponent Reactions
, M.Sc. Thesis Sharif University of Technology ; Matloubi Moghaddam, Firouz (Supervisor)
Abstract
In first part Mesoporous silica (SBA-15) was synthesized by template synthesis method and the surface of SBA-15 was functionalized with 3-glycidoxypropyltrimethoxysilane and 5-Phenyl-1H-tetrazole. Palladium nanoparticles were immobilized on the aforementioned mesoporous support. Characterization of catalyst regarding to its structure, morphology and other parameters was investigated by physiochemical analysis such as XRD, SEM, TEM, and TGA. This heterogeneous catalyst has high capability in reduction of nitrobenzenes and selective oxidation of primary alcohols which respectively gain aminoarenes and benzaldehydes in high yields. Reduction and oxidation reactions are done in water as a green...
Manufacturing and Investigating of Polypropylene/Silica Nanocomposites via in-situ Polymerization and Using Bi-supported Ziegler-Natta Catalyst
, M.Sc. Thesis Sharif University of Technology ; Ramezani Saadat, Ahmad (Supervisor)
Abstract
The main object of this thesis is production and investigation of polypropylene-fumed silica nanocomposites by using bi-supported Ziegler-natta catalytic system and in-situ polymerization. Magnesium ethoxide and fumed silica were used as supports of catalyst. TiCl4 was accompanied by triisobutyl aluminum(TiBA) and diisobutyl phthalate(DIBP) as electron doner constituting Ziegler-Natta catalytic system. Preparation of catalyst and polymerization were taken place in slurry phase under the argon atmosphere. At the beginning of the polymerization experiment, several type of nanocomposites were made under various conditions(such as different Al/Ti molar ratio) to find optimum condition to...
Experimental Investigation of a Nnanofibrous Membrane Preparation for Dye Removal from Colored Wastewater
, Ph.D. Dissertation Sharif University of Technology ; Vossoughi, Manouchehr (Supervisor) ; Mahmoodi, Niyaz Mohammad (Supervisor)
Abstract
In this research, an adsorptive affinity membrane has been prepared based on the combination of the nanofiber structure’s intrinsic characteristic in the dye adsorption and its membrane filtration properties. Electrospinning method has been used to prepare chitosan/poly(vinyl alcohol) (PVA) nanofibers. The morphology and properties of the prepared nanofibrous membranes were characterized using Fourier-transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FE-SEM), image processing, atomic force microscopy (AFM), and thermogravimetric analysis (TGA). Also, the major drawback of electrospun nanofibrous membranes (ENMs) is their low mechanical resistance. So,...
Investigation on Effects of Nanoparticles Presence on Hydrate Formation Characterization During Drilling
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Ali Asghar (Supervisor) ; Zarenezhad, Bahman (Co-Advisor) ; Ramazani, Ahmad (Co-Advisor)
Abstract
In past two decades, the direction of oil and gas exploration has moved towards deep water drilling. The pressure and temperature in these zones are ideal for gas hydrate formation that can cause serious and sometimes uncontrollable issues during drilling operations. Gas hydrate formation while drilling can cause problems such as occurrence of kick and blowout, plug chock and kill line, and change in rheology of drilling mud. On the other hand, nowadays, nanotechnology has created an evolution in engineering sciences and because of the wide range of this science, drilling industry is affected like other industries. In the meantime, because of high yield, high stability and various methods of...
Monitoring wettability alteration by silica nanoparticles during water flooding to heavy oils in five-spot systems: A pore-level investigation
, Article Experimental Thermal and Fluid Science ; Vol. 40, issue , July , 2012 , p. 168-176 ; ISSN: 08941777 ; Mohammadi, S ; Ghazanfari, M. H ; Kharrat, R ; Masihi, M ; Sharif University of Technology
Abstract
It is well known that the displacement efficiency of EOR processes is mainly affected by wettability of porous medium; however, the role of nanoparticles on wettability alteration of pores surfaces remains a topic of debate in the literature. Furthermore, a little is known about how the dispersed silica nanoparticles affect the microscopic/macroscopic recovery efficiency of heavy oils during common immiscible EOR processes such as water flooding. In this study, a series of injection experiments was performed on five-spot glass micromodel which is initially saturated with the heavy oil. Distilled water and dispersed silica nanoparticles in water (DSNW) at different values of weight percent...
Monitoring wettability alteration by silica nanoparticles during water flooding to heavy oils in five-spot systems: A pore-level investigation
, Article Experimental Thermal and Fluid Science ; Volume 40 , July , 2012 , Pages 168-176 ; 08941777 (ISSN) ; Mohammadi, S ; Ghazanfari, M. H ; Kharrat, R ; Masihi, M ; Sharif University of Technology
2012
Abstract
It is well known that the displacement efficiency of EOR processes is mainly affected by wettability of porous medium; however, the role of nanoparticles on wettability alteration of pores surfaces remains a topic of debate in the literature. Furthermore, a little is known about how the dispersed silica nanoparticles affect the microscopic/macroscopic recovery efficiency of heavy oils during common immiscible EOR processes such as water flooding. In this study, a series of injection experiments was performed on five-spot glass micromodel which is initially saturated with the heavy oil. Distilled water and dispersed silica nanoparticles in water (DSNW) at different values of weight percent...
Pore-Scale Monitoring of Wettability Alteration by Silica Nanoparticles During Polymer Flooding to Heavy Oil in a Five-Spot Glass Micromodel
, Article Transport in Porous Media ; Volume 87, Issue 3 , 2011 , Pages 653-664 ; 01693913 (ISSN) ; Mohebbi, A ; Kharrat, R ; Ghazanfari, M. H ; Sharif University of Technology
Abstract
It is well known that the oil recovery is affected by wettability of porous medium; however, the role of nanoparticles on wettability alteration of medium surfaces has remained a topic of debate in the literature. Furthermore, there is a little information of the way dispersed silica nanoparticles affect the oil recovery efficiency during polymer flooding, especially, when heavy oil is used. In this study, a series of injection experiments were performed in a five-spot glass micromodel after saturation with the heavy oil. Polyacrylamide solution and dispersed silica nanoparticles in polyacrylamide (DSNP) solution were used as injected fluids. The oil recovery as well as fluid distribution in...
AFM spectral analysis of self-agglomerated metallic nanoparticles on silica thin films
, Article Current Nanoscience ; Volume 6, Issue 1 , 2010 , Pages 116-123 ; 15734137 (ISSN) ; Sharif University of Technology
2010
Abstract
Stochastic parameters of self-agglomerated metallic nanoparticles on a dielectric film surface were studied using atomic force microscopy (AFM) analysis. In this regard, the rough surfaces including the nanoparticles were analyzed and characterized using structure function, roughness exponent and power spectrum density of the AFM profiles and their gradients, for different metal concentrations and heat treatment temperatures. The diffusion parameters, such as activation energy, of the nanoparticles initially accumulated on the surface into a porous and aqueous silica thin film were obtained using the AFM spectral analysis of the profiles and their gradients. It was found that the tip...
A superhydrophobic silica aerogel with high surface area for needle trap microextraction of chlorobenzenes
, Article Microchimica Acta ; Volume 184, Issue 7 , 2017 , Pages 2151-2156 ; 00263672 (ISSN) ; Bagheri, H ; Sharif University of Technology
Springer-Verlag Wien
2017
Abstract
The authors have synthesized a superhydrophobic silica aerogel by using a sol-gel technique. The material is shown to be an efficient sorbent for needle trap microextraction of chlorobenzenes. Hydrophobicity affects the performance of the sorbent as shown by altering the ratio between tetraethylorthosilicate (TEOS) and methyltrimethoxysilane when synthesizing the sorbent. The observed contact angle (which is >150°) underpins the superhydrophobic properties of the aerogel. The microstructure of the sorbent was investigated by BET adsorption, revealing a surface area above 1000 m2 g−1. The sorbent was applied to needle trap extraction of chlorobenzenes from aqueous samples, and their...