Search for: physicochemical-properties
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    Retina-Choroid-Sclera Permeability for Ophthalmic Drugs in the Vitreous to Blood Direction: Quantitative Assessment

    , Article Pharmaceutical Research ; 2012 , Pages 1-19 ; 07248741 (ISSN) Haghjou, N ; Abdekhodaie, M. J ; Cheng, Y. L ; Sharif University of Technology
    Springer  2012
    Purpose: To determine the outward permeability of retina-choroid-sclera (RCS) layer for different ophthalmic drugs and to develop correlations between drug physicochemical properties and RCS permeability. Methods: A finite volume model was developed to simulate pharmacokinetics in the eye following drug administration by intravitreal injection. The RCS permeability was determined for 32 compounds by best fitting the drug concentration-time profile obtained by simulation with previously reported experimental data. Multiple linear regression was then used to develop correlations between best fit RCS permeability and drugs physicochemical properties. Results: The RCS drug permeabilities had... 

    Hydrolyzed collagen-based hydrogel with salt and pH-responsiveness properties

    , Article Journal of Applied Polymer Science ; Volume 106, Issue 4 , 2007 , Pages 2371-2379 ; 00218995 (ISSN) Pourjavadi, A ; Salimi, H ; Kurdtabar, M ; Sharif University of Technology
    A novel hydrolyzed collagen-based hydrogel has been prepared by grafting the binary mixture of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid onto the collagen backbone in the presence of a cross-linking agent. Its physicochemical properties in aqueous solution were studied. The effect of reaction variables on both gel content and swelling capacity was investigated to achieve a hydrogel with improved absorbency and gel content. The absorbency under load of optimized hydrogel was also investigated by using an absorbency under load tester at various applied pressures. The swelling ratio in various salt solutions was also determined and additionally, the swelling of hydrogels was... 

    Improvement of Edible Oil by Interestrification Process by Lipase

    , M.Sc. Thesis Sharif University of Technology Kouchak Yazdi, Zahra (Author) ; Alemzadeh, Iran (Supervisor) ; Razavi, Jalil (Supervisor)
    Fats and oils are one of the main human food diet components that provide the necessary fatty acids for our body. So the fatty acids available in consuming oils are so important. In this research the mixture of palm and sunflower oils with different compounds: (80:20, 60:40, 50:50, 40:60, 20:80) were used for preparing free- trans shortening by interesterification. For this purpose a special stabilized lipase (Lipozyme TLIM) were used and performed the physicochemical properties: free fatty acids, peroxide value, iodine value, slip melting point, solid fat content, P-anisidine value, soap, oxidative stability at 110 0C, and the profile of fatty acids on the primitive blends and final samples... 

    The effects of a hydrochloric acid pre-treatment on the physicochemical properties and pozzolanic performance of rice husk ash

    , Article Cement and Concrete Composites ; Volume 39 , 2013 , Pages 131-140 ; 09589465 (ISSN) Gholizadeh Vayghan, A ; Khaloo, A. R ; Rajabipour, F ; Sharif University of Technology
    This paper investigates the effects of acid normality (0.01-6 N HCl) and combustion retention time (0.25- 16 hours) on the pozzolanic properties of pre-combustion acid-treated rice husk ash. The pozzolanic reactivity was quantified by adding ground ash to saturated Ca(OH)2 solutions and monitoring the time-dependent electrical conductivity and pH of the solutions. Also, the strength activity of ashes from different processes was measured by testing the compressive strength of mortars. It was observed that acid treatment results in ashes with higher SiO2 content, lower alkali and unburned carbon content, better grindability, and smaller particle size, in comparison with ash from non-acid... 

    Determination of nanoparticles using UV-Vis spectra

    , Article Nanoscale ; Volume 7, Issue 12 , Feb , 2015 , Pages 5134-5139 ; 20403364 (ISSN) Behzadi, S ; Ghasemi, F ; Ghalkhani, M ; Ashkarran, A. A ; Akbari, S. M ; Pakpour, S ; Hormozi Nezhad, M. R ; Jamshidi, Z ; Mirsadeghi, S ; Dinarvand, R ; Atyabi, F ; Mahmoudi, M ; Sharif University of Technology
    Royal Society of Chemistry  2015
    Nanoparticles (NPs) are increasingly being used in different branches of science and in industrial applications; however, their rapid detection and characterization at low concentration levels have remained a challenge; more specifically, there is no single technique that can characterize the physicochemical properties of NPs (e.g. composition and size). In this work we have developed a colorimetric sensor array for defining the physicochemical properties of NPs in aqueous solution with ultra-low concentrations (e.g. 10-7g ml-1 for gold NPs). Various NPs were readily identified using a standard chemometric approach (i.e. hierarchical clustering analysis), with no misclassifications over 400... 

    Nanoparticle-based optical sensor arrays

    , Article Nanoscale ; Volume 9, Issue 43 , 2017 , Pages 16546-16563 ; 20403364 (ISSN) Bigdeli, A ; Ghasemi, F ; Golmohammadi, H ; Abbasi Moayed, S ; Nejad, M. A. F ; Fahimi-Kashani, N ; Jafarinejad, S ; Shahrajabian, M ; Hormozi-Nezhad, M. R ; Sharif University of Technology
    As in many other methods that have integrated nanoparticles (NPs), the chemical nose/tongue strategy has also progressed greatly since the entrance of NPs into this field. The fascinating tunable physicochemical properties of NPs have made them powerful candidates for array-based sensing platforms and have enabled the development of real-time, sensitive and portable systems that are able to target complex mixtures of analytes. In particular, the unique optical properties of NPs have a key role in providing promising array-based sensing approaches. This review will describe the main aspects and processes of most common NP-based optical sensor arrays. The fundamental steps in the design of a... 

    Electroosmotic flow and ionic conductance in a pH-regulated rectangular nanochannel

    , Article Physics of Fluids ; Volume 29, Issue 6 , 2017 ; 10706631 (ISSN) Sadeghi, M ; Saidi, M. H ; Sadeghi, A ; Sharif University of Technology
    Infinite series solutions are obtained for electrical potential, electroosmotic velocity, ionic conductance, and surface physicochemical properties of long pH-regulated rectangular nanochannels of low surface potential utilizing the double finite Fourier transform method. Closed form expressions are also obtained for channels of large height to width ratio for which the depthwise variations vanish. Neglecting the Stern layer impact, the effects of EDL (Electric Double Layer) overlap, multiple ionic species, and association/dissociation reactions on the surface are all taken into account. Moreover, finite-element-based numerical simulations are conducted to account for the end effects as well... 

    Adsorption of terephthalic acid and p-toluic acid from aqueous solution using metal organic frameworks: Effect of molecular properties of the adsorbates and structural characteristics of the adsorbents

    , Article Desalination and Water Treatment ; Volume 66 , 2017 , Pages 367-382 ; 19443994 (ISSN) Behvandi, A ; Khorasheh, F ; Safekordi, A. A ; Sharif University of Technology
    Desalination Publications  2017
    The adsorptive removal of terephthalic acid (TPA) and p-toluic acid (p-tol) by metal organic frameworks (MOF) of Cu-BTC, Fe-BTC, MIL-101(Cr) and MIL-53(Al) was investigated in this study. The influence of various factors including solution pH, contact time, and initial concentration of TPA and p-tol solutions on the adsorption behavior was evaluated. Different adsorption isotherms and kinetic models were used to fit experimental adsorption data. It was found that the Langmuir and Redlich-Peterson adsorption isotherms were adequate to represent the experimental data (R2 > 0.97) and that the adsorption kinetics was well-represented by a pseudo-second-order kinetic model (R2 > 0.98). The zeta... 

    Role of graphene surface ripples and thermal vibrations in molecular dynamics of C60

    , Article Journal of Physical Chemistry C ; Volume 123, Issue 32 , 2019 , Pages 20026-20036 ; 19327447 (ISSN) Mofidi, S. M ; Nejat Pishkenari, H ; Ejtehadi, M. R ; Akimov, A. V ; Sharif University of Technology
    American Chemical Society  2019
    Nanocars are artificial molecular machines with chassis, axles, and wheels designed for nanoscale transport at materials' surfaces. Understanding the dependence of surface dynamics of nanocars on the substrate's physicochemical properties is critical to the design of the transport properties of such man-made nanoscale devices. Among the multitude of potential substrates for the nanotransporters, graphene exhibits intrinsic ripples on its surface, which may affect the surface dynamics of nanocars. In this work, we report our molecular dynamics study of motion of C60, a popular nanocar wheel, on the graphitic substrates with systematically controllable surface ripples. We find that surface... 

    Optical nanoprobes for chiral discrimination

    , Article Analyst ; Volume 145, Issue 20 , 2020 , Pages 6416-6434 Bigdeli, A ; Ghasemi, F ; Fahimi Kashani, N ; Abbasi Moayed, S ; Orouji, A ; Jafar Nezhad Ivrigh, Z ; Shahdost Fard, F ; Hormozi Nezhad, M. R ; Sharif University of Technology
    Royal Society of Chemistry  2020
    Chiral discrimination has always been a hot topic in chemical, food and pharmaceutical industries, especially when dealing with chiral drugs. Enantiomeric recognition not only leads to better understanding of the mechanism of molecular recognition in biological systems, but may further assist in developing useful molecular devices in biochemical and pharmaceutical studies. By emerging nanotechnology and exploiting nanomaterials in sensing applications, a great deal of attention has been given to the design of optical nanoprobes that are able to discriminate enantiomers of chiral analytes. This review explains how engineering nanoparticles (NPs) with desired physicochemical properties allows... 

    Deep eutectic solvents: Cutting-edge applications in cross-coupling reactions

    , Article Green Chemistry ; Volume 22, Issue 12 , 2020 , Pages 3668-3692 Hooshmand, S. E ; Afshari, R ; Ramón, D. J ; Varma, R. S ; Sharif University of Technology
    Royal Society of Chemistry  2020
    Deep eutectic solvents (DESs), surmised as "the organic reaction medium of the century", have reverberated a new symphony throughout the present green millennium. A brief historical account of the DES systems and their physicochemical properties as task-specific and designer solvents for cross-coupling reactions are appraised including the hole theory that explains the underlying mechanistic pathway for this emerging neoteric medium. The insights into cross-coupling reactions and their applications are included, highlighting the significant achievements pertaining to the dual role of DESs as a solvent and catalyst. In addition, popular "name-reactions"for the carbon-carbon and... 

    Using nano-QSAR to determine the most responsible factor(s) in gold nanoparticle exocytosis

    , Article RSC Advances ; Volume 5, Issue 70 , 2015 , Pages 57030-57037 ; 20462069 (ISSN) Bigdeli, A ; Hormozi Nezhad, M. R ; Parastar, H ; Sharif University of Technology
    Royal Society of Chemistry  2015
    There are, to date, few general answers to fundamental questions related to the interactions of nanoparticles (NPs) with living cells. Studies reported in the literature have delivered only limited principles about the nano-bio interface and thus the biological behavior of NPs is yet far from being completely understood. Combining computational tools with experimental approaches in this regard helps to precisely probe the nano-bio interface and allows the development of predictive and descriptive relationships between the structure and the activity of nanomaterials. In the present contribution, a nano-quantitative structure-activity relationship (nano-QSAR) model has been statistically... 

    A new functionalized magnetic nanocomposite of poly(methylacrylate) for the efficient removal of anionic dyes from aqueous media

    , Article RSC Advances ; Volume 6, Issue 10 , 2016 , Pages 7982-7989 ; 20462069 (ISSN) Pourjavadi, A ; Abedin Moghanaki, A ; Nasseri, S. A ; Sharif University of Technology
    Royal Society of Chemistry 
    A new magnetic nano-adsorbent was synthesized via the radical polymerization of methyl acrylate on modified Fe3O4 nanoparticles, followed by its functionalization by amidation of the methyl ester groups using pentaethylenehexamine, to create active adsorption sites for removing anionic dyes from aqueous media. Physicochemical properties of the adsorbent were then characterized by SEM, TEM, XRD, FTIR, TGA and CHN analysis. The prepared nanocomposite was used as adsorbent for the removal of anionic dyes, naphthol green B and chromeazurol S, from aqueous solution and assessed in view of the kinetics and isotherm adsorption, and the effect of solution pH, contact time and initial dye... 

    Geometry effect on electrokinetic flow and ionic conductance in pH-regulated nanochannels

    , Article Physics of Fluids ; Volume 29, Issue 12 , 2017 ; 10706631 (ISSN) Sadeghi, M ; Saidi, M. H ; Moosavi, A ; Sadeghi, A ; Sharif University of Technology
    Semi-analytical solutions are obtained for the electrical potential, electroosmotic velocity, ionic conductance, and surface physicochemical properties associated with long pH-regulated nanochannels of arbitrary but constant cross-sectional area. The effects of electric double layer overlap, multiple ionic species, and surface association/dissociation reactions are all taken into account, assuming low surface potentials. The method of analysis includes series solutions which the pertinent coefficients are obtained by applying the wall boundary conditions using either of the least-squares or point matching techniques. Although the procedure is general enough to be applied to almost any... 

    Novel aspects of application of cadmium telluride quantum dots nanostructures in radiation oncology

    , Article Applied Physics A: Materials Science and Processing ; Volume 123, Issue 8 , 2017 ; 09478396 (ISSN) Fazaeli, Y ; Zare, H ; Karimi, S ; Rahighi, R ; Feizi, S ; Sharif University of Technology
    Springer Verlag  2017
    In the last two decades, quantum dots nanomaterials have garnered a great deal of scientific interest because of their unique properties. Quantum dots (QDs) are inorganic fluorescent nanocrystals in the size range between 1 and 20 nm. Due to their structural properties, they possess distinctive properties and behave in different way from crystals in macro scale, in many branches of human life. Cadmium telluride quantum dots (CdTe QDs) were labeled with 68Ga radio nuclide for fast in vivo targeting and coincidence imaging of tumors. Using instant paper chromatography, the physicochemical properties of the Cadmium telluride quantum dots labeled with 68Ga NPs (68Ga@ CdTe QDs) were found high... 

    Molecular interaction between three-dimensional graphene aerogel and enzyme solution: effect on enzyme structure and function

    , Article Journal of Molecular Liquids ; Volume 265 , 2018 , Pages 565-571 ; 01677322 (ISSN) Ehtesabi, H ; Bagheri, Z ; Eskandari, F ; Ahadian, M. M ; Sharif University of Technology
    New membrane materials and processes have been extensively developed due to urgent needs for much more economic separation processes. Recently, graphene has been confirmed to be an excellent separation membrane. As there is no support in the obtained three-dimensional (3D) architecture constructed from tubular graphene network, it is possible to take full advantage of the large surface of graphene. In this study 3D graphene aerogels were synthesized by a simple method and modified to adjust hydrophilicity of the samples to achieve high liquid volumetric rate. Modified samples were used for the filtration of the enzymes including amylase, cellulase, lipase and protease. Slightly differently... 

    Mesoporous nanostructured Ni/MgAl2O4 catalysts: Highly active and stable catalysts for syngas production in combined dry reforming and partial oxidation

    , Article International Journal of Hydrogen Energy ; Volume 44, Issue 21 , 2019 , Pages 10427-10442 ; 03603199 (ISSN) Jalali, R ; Nematollahi, B ; Rezaei, M ; Baghalha, M ; Sharif University of Technology
    Elsevier Ltd  2019
    In this paper, the combination of dry reforming and partial oxidation of methane on nickel catalysts supported on mesoporous MgAl2O4 was investigated. The support was prepared by a facile sol-gel route using propylene oxide as a gelation agent. The characterizations of the catalysts were performed by BET, XRD, TPR, TPO, TPH, UV–vis, CO-dispersion, SEM and TEM techniques. In addition, the effects of nickel content, reaction and reduction temperatures, feed ratio and the GHSV value on the physicochemical and catalytic properties were studied. The results revealed that the nickel content had an optimum value of 7.5 wt% and the catalyst with this content of nickel exhibited the highest activity.... 

    Potential effects of alginate–pectin biocomposite on the release of folic acid and their physicochemical characteristics

    , Article Journal of Food Science and Technology ; Volume 57, Issue 9 , March , 2020 , Pages 3363-3370 Kiaei Pour, P ; Alemzadeh, I ; Vaziri, A. S ; Beiroti, A ; Sharif University of Technology
    Springer  2020
    Potential effects of folates on the treatment of several human diseases like cognitive function, neural tube defects, coronary heart disease and certain kinds of cancers have been discovered. However, the stability of folic acid against adverse conditions is a great concern. The present study investigates various alginate (A)–pectin (P) gastrointestinal-resistant hydrogel to immobilize folic acid. This involves evaluating different compositions of alginate–pectin to achieve higher encapsulation efficiency and stability during simulated gastric (SG) and simulated intestinal (SI) conditions. Coated alginate hydrogels with pectin resulted significant (p < 0.05) better protection of folic acid... 

    Development and verification of a model to describe an immobilized glucose isomerase packed bed bioreactor

    , Article Biochemical Engineering Journal ; Volume 40, Issue 2 , 2008 , Pages 328-336 ; 1369703X (ISSN) Khalilpour, R ; Roostaazad, R ; Sharif University of Technology
    In this paper, the performance of immobilized packed bed glucose isomerase enzyme was mathematically modeled. A modified Michaelis-Menten type relation was used to describe the enzyme kinetics. Mass transfer inside the biocatalyst particle and through the bed column was analyzed simultaneously. Using measured data, physicochemical properties including diffusivity, viscosity and density of sugar solutions were correlated with its concentrations and were used to provide precision in solving the set of model equations. Model equations were solved using the Runge-Kutta and Gauss-Seidel algorithms and finite difference numerical method in MATLAB environment. Model output was used to demonstrate... 

    Phosphomolybdic acid/graphene oxide as novel green catalyst using for biodiesel production from waste cooking oil via electrolysis method: Optimization using with response surface methodology (RSM)

    , Article Fuel ; Volume 287 , 2021 ; 00162361 (ISSN) Helmi, M ; Tahvildari, K ; Hemmati, A ; Aberoomand azar, P ; Safekordi, A ; Sharif University of Technology
    Elsevier Ltd  2021
    In this study, biodiesel (FAME) was prepared using a novel heterogeneous catalyst of phosphomolybdic acid (H3PMo12O40, HPMo)/support graphene oxide (GO). The characterization of the catalyst was evaluated by SEM, EDX, Map analysis, TEM, FT-IR, and Raman analyses. The production of biodiesel from waste cooking oil (WCO) was carried out by the electrolysis method. The process of the trans-esterification reaction was optimized by applying the response surface methodology (RSM) based on the central composite design (CCD) approach. The effects of four independent variables of methanol to oil molar ratio (6–12 mol:mol), catalyst weight (0.5–1.5 wt%), time (8–24 h), and voltage (30–70 V) were...