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hydrolysis
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Microwave-assisted rapid hydrolysis and preparation of thioamides by Willgerodt-Kindler reaction
, Article Synthetic Communications ; Volume 31, Issue 2 , 2001 , Pages 317-321 ; 00397911 (ISSN) ; Ghaffarzadeh, M ; Sharif University of Technology
2001
Abstract
Aldehydes and aryl alkyl ketones were efficiently transformed to thioamides with the same number of carbon atoms via Willgerodt-Kindler reaction under microwave irradiation in solvent-free conditions. The thioamides obtained were hydrolyzed to corresponding carboxylic acids with microwave dielectric heating in one minute. Both reactions are very fast and the yields are excellent
Kinetic study of catalytic hydrolysis reaction of methyl acetate to acetic acid and methanol
, Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 30, Issue 5 , 2006 , Pages 595-606 ; 03601307 (ISSN) ; Rahimi, N ; Eftekhari, A. A ; Nasr, M. J ; Sharif University of Technology
2006
Abstract
The reaction kinetics and chemical equilibrium of the reversible catalytic hydrolysis reaction of a methyl acetate to acetic acid and methanol using a strongly acidic ion exchange resin catalyst named Amberlyst 15 were studied. To investigate the different behavior of Amberlyst 15 in the adsorption of reactants and product species, the equilibrium behavior of binary non-reactive liquid mixtures, consisting of one reactant and one product were studied experimentally. The Langmuir model was used to describe the equilibrium condition, quantitatively. Then the employed model was compared with the more complicated thermodynamic models to describe the equilibrium between the catalytic polymer...
A new study on binder performance and formulation modification of anti-corrosive primer based on ethyl silicate resin
, Article Progress in Organic Coatings ; Volume 65, Issue 3 , 2009 , Pages 410-413 ; 03009440 (ISSN) ; Sherafati, S. A ; Hashemi, M. M ; Sharif University of Technology
2009
Abstract
Zinc-rich ethyl silicate coatings are quite successful in protecting steel against corrosion under severe exposing conditions. In spite of providing excellent cathodic protection to steel structure after film curing, two-component zinc-rich ethyl silicate coatings have some limitations, one of which is inadequate shelf life as a result of in-can binder gelation. In this work, the preparation steps of ethyl silicate such as pre-hydrolysis, dehydration and organometallic reactions were surveyed and herein an approach towards understanding the cause and effect relationship of the use of ingredients is presented. The effects of water and catalytic acid dosages on gel time under accelerated...
Ethanol production from sugarcane bagasse by means of on-site produced and commercial enzymes; A comparative study
, Article Periodica Polytechnica: Chemical Engineering ; Volume 56, Issue 2 , 2012 , Pages 91-96 ; 03245853 (ISSN) ; Yaghmaei, S ; Andalibi, M. R ; Ghazvini, S ; Sharif University of Technology
2012
Abstract
In this study ethanol was produced without using expensive commercial enzymes from sugarcane bagasse. Alkali pretreatment was used to prepare biomass before enzymatic hydrolysis. The comparison between NaOH, KOH and Ca(OH)2 revealed that NaOH has been more effective on bagasse structure. The required enzymes for biomass hydrolysis were produced by bagasse solid state fermentation using three fungi: Trichoderma longibrachiatum, T. reesei and Aspergillus niger. Results indicated enzyme solution produced by A. niger has functioned better than the other two in cellulose conversion during sole hydrolysis. Ethanol was produced by simultaneous saccharification and fermentation (SSF) with on-site...
TiO2 nanostructured films on mica using liquid phase deposition
, Article Materials Chemistry and Physics ; Volume 107, Issue 2-3 , 2008 , Pages 449-455 ; 02540584 (ISSN) ; Taghavinia, N ; Sharif University of Technology
2008
Abstract
Liquid phase deposition is a method to grow conformal TiO2 films with good crystallinity on various substrates. The growth depends on the hydrophilicity of the substrate surface and we found that mica is a substrate capable of forming uniform and thick films. Films were grown using an aqueous solution of TiF4 through a hydrolysis-condensation process. We have studied films properties; morphology, porosity and thickness, in terms of growth conditions, i.e. TiF4 concentration, growth temperature, deposition time and pH. The porosity of films was shown to rapidly increase from about 18% to about 25% and remained the same for longer growth times. The growth process of films could be identified...
Optimization of sugarcane bagasse hydrolysis process by economic criteria
, Article Advances in Environmental Biology ; Volume 5, Issue 7 , 2011 , Pages 1900-1903 ; 19950756 (ISSN) ; Alavi, A ; Vosoughi, M ; Ardjmand, M ; Seifkordi, A. A ; Zabihi, V ; Radjabi, R ; Hedayat, N ; Sharif University of Technology
2011
Abstract
Various processes are used for production of value-added materials from sugarcane bagasse. Hydrolysis processes are the most commonly used methods for producing new products from this low value byproduct. Sulfuric acid hydrolysis processes are the best processing options due to their fast reaction and low process cost. The goal of this study was to investigate an optimized hydrolysis method which can produce fermentable sugar-containing liquor economically. In the other words it was designed to minimize the toxic materials to a level that cannot affect the citric acid production by Aspergillus niger. Results showed the optimum condition for one-step hydrolysis processes occurs at the...
A convenient synthesis of 3-formyl-2-thioacetamide-indole derivatives via the one-pot reaction of indolin-2-thiones, isocyanides and chloroacetylchloride
, Article Tetrahedron Letters ; Volume 56, Issue 52 , 2015 , Pages 7190-7192 ; 00404039 (ISSN) ; Matloubi Moghaddamb, F ; Sadeghi Erami, M ; Sharif University of Technology
Abstract
An efficient method has been developed to construct 3-formyl-2-thioacetamide-indoles via a one-pot, two-step procedure involving condensation of isocyanides with indolin-2-thiones to give a 3-aminomethylene-indolin-2-thione intermediate, followed by regioselective reaction with chloroacetylchloride and subsequent hydrolysis
Partially hydrolyzed kappa carrageenan - polyacrylonitrile as a novel biopolymer-based superabsorbent hydrogel: synthesis, characterization, and swelling behaviors
, Article Polymer Engineering and Science ; Volume 46, Issue 12 , 2006 , Pages 1778-1786 ; 00323888 (ISSN) ; Pourjavadi, A ; Sharif University of Technology
2006
Abstract
In this paper, synthesis and swelling behavior of a novel superabsorbent hydrogel based on kappa carrageenan (κC) and polyacrylonitrile (PAN) was investigated. To achieve partially hydrolyzed κC-PAN hydrogel, physical mixture of κC and PAN was hydrolyzed by NaOH solution. During alkaline hydrolysis, the nitrile groups of PAN are converted to a mixture of hydrophilic carboxamide and carboxylate groups follow by in situ crosslinking of the grafted PAN chains. The reaction variables affecting on the swelling capacity of the hydrogel were systematically optimized to achieve a hydrogel with swelling capacity as high as possible. Under the optimized conditions concluded, super swelling hydrogel...
Synthesis and Investigation of The Possibility of Using Hydrolyzed Acrylamide Copolymers Containing Hydrophobic Monomers for Water Purification (Flocculation)
, M.Sc. Thesis Sharif University of Technology ; Ramazani Saadatabadi, Ahmad (Supervisor)
Abstract
to achieve a stable elimination of colloidal suspended particles, polymer flocculants such as polyacrylamide and its derivative have been more used. To improve the performance of removing turbidity, reducing settling time, and better dewatering from sediments, hydrophobic styrene monomer copolymerized with acrylamide monomer. In this study the copolymer of acrylamide and styrene was synthesized by inverse emulsion polymerization, then this copolymer undergoes hydrolysis to form anionic groups on the polymer backbone. FT-IR, H NMR, and TGA analyses were carried out to investigate the structure of the copolymer. To evaluate flocculation, turbidity tests, zeta potential, and sedimentation rate...
Effect of brookite presence on nanocrystalline anatase - Rutile phase transformation
, Article International Journal of Nanotechnology ; Volume 6, Issue 10-11 , 2009 , Pages 961-972 ; 14757435 (ISSN) ; Askari, M ; Sasani Ghamsari, M ; Sharif University of Technology
2009
Abstract
TiO2nanocrystals were prepared by hydrolysis and peptisation of titanium isopropoxide under different pH values. The as-prepared powder of very fine anatase crystallites ranges from 8 nm in acidic solution of pH 3 to 10 nm in basic solution of pH 8. Heat treatment of the powders leads to grain growth and anatase - rutile transformation. Experimental results have shown that the anatase to rutile phase transformation in the heat-treated powders depend not only on primary crystallite size but also the presence of brookite phase. It is observed that in the powders with the same size the presence brookite phase would accelerate the anatase to rutile transformation. Furthermore it has been found...
A new approach for preparation of semi-transparent superhydrophobic coatings by ultrasonic spray hydrolysis of methyltrimethoxysilane
, Article Progress in Organic Coatings ; Volume 135 , 2019 , Pages 248-254 ; 03009440 (ISSN) ; Sabour Rouh Aghdam, A ; Nazari, M ; Bayat, A ; Saievar Iranizad, E ; Sharif University of Technology
Elsevier B.V
2019
Abstract
A novel nebulizing spray hydrolysis approach was used for preparation of semi-transparent superhydrophobic coatings. Methyltrimethoxysilane was dissolved in water:ethanol mixture and ultrasonically sprayed on different substrates. Superhydrophobic coatings with a contact angle (CA) as high as 164° and a sliding angle below 5° were obtained. FESEM and AFM revealed a hierarchical micro-nano binary structure with nanometric roughness of the coatings. The coated glass substrate exhibited transmittance close to 80%. The prepared coating showed great self-cleaning and water jet repellency behaviors. The superhydrophobicity of the samples was remained after subjecting to ambient conditions for 50...
Bioresorbable composite polymeric materials for tissue engineering applications
, Article International Journal of Polymeric Materials and Polymeric Biomaterials ; 2020 ; Mohammadi Nasr, S ; Rabiee, N ; Bagherzadeh, M ; Ahmadi, S ; Rabiee, M ; Tahriri, M ; Tayebi, L ; Hamblin, M. R ; Sharif University of Technology
Taylor and Francis Inc
2020
Abstract
This review covers the development of bioresorbable polymeric composites for applications in tissue engineering. Various commercially available bioresobable polymers are described, with emphasis on recent bioresorbable composites based on natural and synthetic polymers. Bioresorbable polymers contain hydrolyzable bonds, which are subjected to chemical degradation via either reactive hydrolysis or enzyme-catalyzed active hydrolysis. For synthetic polymers, chemical hydrolysis is the most important mode of degradation. The degradation rate can be controlled by varying the molecular weight and crystallinity. Examples of bioresorbable polymers are: polyurethane, poly(D,L)lactide,...
Bioresorbable composite polymeric materials for tissue engineering applications
, Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 70, Issue 13 , 2021 , Pages 926-940 ; 00914037 (ISSN) ; Mohammadi Nasr, S ; Rabiee, N ; Bagherzadeh, M ; Ahmadi, S ; Rabiee, M ; Tahriri, M ; Tayebi, L ; Hamblin, M. R ; Sharif University of Technology
Bellwether Publishing, Ltd
2021
Abstract
This review covers the development of bioresorbable polymeric composites for applications in tissue engineering. Various commercially available bioresobable polymers are described, with emphasis on recent bioresorbable composites based on natural and synthetic polymers. Bioresorbable polymers contain hydrolyzable bonds, which are subjected to chemical degradation via either reactive hydrolysis or enzyme-catalyzed active hydrolysis. For synthetic polymers, chemical hydrolysis is the most important mode of degradation. The degradation rate can be controlled by varying the molecular weight and crystallinity. Examples of bioresorbable polymers are: polyurethane, poly(D,L)lactide,...
Construction of Membrane Bioreactor for Glucose Separation from Enzymatic Hydrolysis of Corn Fiber
, M.Sc. Thesis Sharif University of Technology ; Soltanieh, Mohammad (Supervisor)
Abstract
Production of cellulosic ethanol from lignocellulosic biomass represents a alternative to the petroleum fuel due to its renewable nature and sustainable availability. The major strategy used for cellulosic ethanol production includes three main steps of biomass pretreatment, enzymatic hydrolysis and ethanol fermentation. The enzymatic hydrolysis contributes significantly to the cost of cellulosic ethanol and from the process economics perspective, the improvement in the enzymatic hydrolysis step is a prerequisite. The fiber is composed of cell wall fractions and residual starch which can be hydrolyzed to reducing sugar.A method of hydrolysis of polysaccharides in corn fiber, feed...
Synthesis of an alginate-poly(sodium acrylate-co-acrylamide) superabsorbent hydrogel with low salt sensitivity and high pH sensitivity
, Article Journal of Applied Polymer Science ; Volume 101, Issue 5 , 2006 , Pages 2927-2937 ; 00218995 (ISSN) ; Sharifnia, N ; Hosseinzadeh, H ; Sharif University of Technology
2006
Abstract
This article describes the synthesis and swelling behavior of a superabsorbing hydrogel based on sodium alginate (NaAlg) and polyacrylonitrile (PAN). The physical mixture of NaAlg and PAN was hydrolyzed with a solution of NaOH to yield an alginate-poly(sodium acrylate-co-acrylamide) [Alg-poly(NaAA-co-AAm)] superabsorbent hydrogel. A proposed mechanism for hydrogel formation was suggested, and the structure of the product was established with Fourier transform infrared spectroscopy. The effects of reaction variables were systematically optimized to achieve a hydrogel with a swelling capacity as high as possible. Under the optimized conditions concluded, the maximum capacity of swelling in...
A convenient one-step preparation of chitosan-poly(sodium acrylate-co-acrylamide) hydrogel hybrids with super-swelling properties
, Article Journal of Applied Polymer Science ; Volume 99, Issue 4 , 2006 , Pages 1615-1619 ; 00218995 (ISSN) ; Pourjavadi, A ; Zohuriaan Mehr, M. J ; Sharif University of Technology
2006
Abstract
Hydrogel hybrids were conveniently prepared from alkaline hydrolysis of chitosan-poly(acrylonitrile) mixture under highly practical conditions. The reaction of chitosan alkoxide anions with nitrile groups of poly(acrylonitrile) (PAN) forms crosslinking points and results in a three-dimensional network with superswelling ability in aqueous media. The hydrogel hybrid was identified using FTIR spectroscopy. The PAN content of the hydrolyzing feed affects proportionally the swelling capacity of the hydrogel hybrid. The swelling properties (capacity and rate) of the ampholytic hydrogel were investigated preliminarily. © 2005 Wiley Periodicals, Inc
Mechanisms and kinetics of Thiotepa and tepa hydrolysis: DFT study
, Article Journal of Molecular Modeling ; Volume 18, Issue 8 , 2012 , Pages 3563-3576 ; 16102940 (ISSN) ; Fattahi, A ; Sharif University of Technology
Springer
2012
Abstract
N,N′,N″-triethylenethiophosphoramide (Thiotepa) and its oxo analogue (Tepa) as the major metabolite are trifunctional alkylating agents with a broad spectrum of antitumor activity. In vivo and vitro studies show alkylation of DNA by Thiotepa and Tepa can follow two pathways, but it remains unclear which pathway represents the precise mechanism of action. In pathway 1, these agents are capable of forming cross-links with DNA molecules via two different mechanisms. In the first mechanism, the ring opening reaction is initiated by protonating the aziridine, which then becomes the primary target of nucleophilic attack by the N7-Guanine. The second one is a direct nucleophilic ring opening of...
Hydrolysis kinetics of lead silicate glass in acid solution
, Article Journal of Nuclear Materials ; Volume 389, Issue 3 , 2009 , Pages 427-431 ; 00223115 (ISSN) ; Sadrnezhaad, Kh ; Raisali, G ; Hamidi, A ; Sharif University of Technology
2009
Abstract
Hydrolysis kinetics of the lead silicate glass (LSG) with 40 mol% PbO in 0.5 N HNO3 aqueous acid solution was investigated. The surface morphology and the gel layer thickness were studied by scanning electron microscopy (SEM) micrographs. Energy dispersive X-ray spectroscopy (EDS) and inductively coupled plasma spectroscopy (ICP) were used to determine the composition of the gel layer and the aqueous solution, respectively. The silicon content of the dissolution products was determined by using weight-loss data and compositions of the gel layer and the solution. The kinetic parameters were determined using the shrinking-core-model (SCM) for rate controlling step. The activation energy...
DFT Study on Mechanism and Kinetic of Thiotepa and Tepa Interaction with its DNA Receptor
,
M.Sc. Thesis
Sharif University of Technology
;
Fattahi, Alireza
(Supervisor)
Abstract
N, N′, N″-triethylenethiophosphoramide (Thiotepa) and its oxo analogue (Tepa) as the major metabolite are trifunctional alkylating agents with a broad spectrum of antitumor activity. In vivo and vitro studies show alkylation of DNA by Thiotepa and Tepa can follow two pathways, but it remains unclear which pathway represents the precise mechanism of action. In pathway 1, these agents are capable of forming cross-links with DNA molecules which can be carried out via two different mechanisms. In the first mechanism, the ring opening reaction is initiated by protonating the aziridine, which then becomes the primary target of nucleophilic attack by the N7-Guanine of DNA. The second one is the...
Improvement of Collapsible Soils Using Biocementation Method (Case Study of Gorgan Loess)
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
Collapsible soils have been encountered in many parts of the world such as Gorgan (a city in North of Iran). In these soils, sudden and large volume changes occur while the water content, loading pressure or both, are passed a threshold limit. One of the serious problems that may occur in the structures constructed on collapsible soils is the catastrophic settlements resulting from increase of water content in the soils. In this research, improvement of mechanical properties of loessial collapsible soil taken from Gorgan has been investigated using biocementation method. There are some microbial processes that can lead to biocementation, which one of them is microbially induced calcite...