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Mechanical properties and structure of solvent processed novolac resin/layered silicate: Development of interphase region
, Article RSC Advances ; Volume 5, Issue 98 , Jun , 2015 , Pages 80875-80883 ; 20462069 (ISSN) ; Shojaei, A ; Sharif University of Technology
Royal Society of Chemistry
2015
Abstract
Composites of phenol-formaldehyde (PF) resin with Closite Na+ and Closite 30B up to 20 wt% loadings were prepared by solution mixing. Tensile testing showed that both pristine and organically modified clays increased considerably the mechanical properties of PF resin at 2.5 wt% loading followed by marginal improvement or even sacrificed properties at high loadings. DMA and DSC analyses suggested development of a highly crosslinked and well adhered interphase around silicate layers. A novel three-phase model considering the interphase region was proposed to predict composite modulus. The model was successfully employed to correlate morphological characteristics and mechanical properties of...
An Investigation on the Behavior of Nanoparticle Filled Brake Friction Materialls
, M.Sc. Thesis Sharif University of Technology ; Shojaei, Akbar (Supervisor)
Abstract
The most common type of polymer based composite friction materials are usually in vehicles as the brake pads are used and must characteristics such as high wear resistance, low weight, durability, low noise and stable friction coefficient. Polymer matrix, in addition to providing other material suitable for storage, the final properties, including mechanical properties, heat, friction and wear is also effective. Thermoset resin polymer matrixes (usually phenolic resin) are used in the brake pads which used for automotive and in some cases, rubber particles as powder formulations may be entered, in order to achieve good properties of rubber and resin simultaneously. Nanofillers because of...
Effect of alumina nanoparticle on the tribological performance of automotive brake friction materials
, Article Journal of Reinforced Plastics and Composites ; Vol. 33, issue. 2 , October , 2014 , pp. 166-178 ; ISSN: 07316844 ; Shojaei, A ; Jahanmard, P ; Sharif University of Technology
2014
Abstract
Brake friction materials filled with nanoalumina were produced by both conventional and solvent-assisted mixing methods. It was shown that nanoalumina loading led to the reduction of friction coefficient and improvement in mechanical, wear and thermal behaviors. Such behavior was attributed to the role of nanoalumina in producing stable friction layer and easy conduction path in matrix. It was postulated that nanoalumina is able to attach on the surface of microalumina facilitating the rolling of microalumina at interface. Solution-processed samples exhibited lower improvement in tribological and mechanical properties compared to the conventional mixing due to the limited interaction between...
Experimental and theoretical study on the mechanical properties of novolac phenolic resin nanocomposites: Effects of nanoclay and multiwallwed carbon nanotube
, Article ECCM 2012 - Composites at Venice, Italy, Proceedings of the 15th European Conference on Composite Materials, 24 June 2012 through 28 June 2012 ; 2012 ; 9788888785332 (ISBN) ; Shojaei, A ; Faghihi, M ; Sharif University of Technology
European Conference on Composite Materials, ECCM
2012
Abstract
The present work focused on the characterization of mechanical properties of novolac phenolic resin (PF) filled with two types of clays, including modified and unmodified ones, and multiwalled carbon nanotube (MWCNT). It was found that the solution mixing method is able to disperse the nanoparticles within the PF resin appropriately. It was also shown that the unmodified clay (Closite Na+) has the highest influence on the mechanical properties possibly due to the good level of dispersion as well as the good interfacial interaction. Theoretical analysis based on the rubber elasticity theory showed that the nanoparticles influence the evolution of crosslinking density and network structure
Constructing a Robust Least Squares Support Vector Machine Based on Lp-norm and L∞-norm
, M.Sc. Thesis Sharif University of Technology ; Mahdavi Amiri, Nezamoddin (Supervisor)
Abstract
In the last decades, Support Vector Machine (SVM) has been used for supervised classification due to its wide applications. In addition, SVM is a mathematical programming tool, that as other optimization-based approaches, turns to be useful for a successful development of supervised classification. Based on current research in the literature, we explain the extension of a developed method for SVM using L2-norm to the more general case of Lp-norms with p > 1. The Kernel function is used frequently in the L2-SVM model, but the multidimensional Kernel is used as a general function in Lp-SVM. Finally, we use Lp-LSSVM model, with 0
Performance-based assessment of steel jacket platforms by wave endurance time method
, Article Ships and Offshore Structures ; Oct , 2015 , Page 1-11 ; 17445302 (ISSN) ; Diznab, M. A. D ; Mehdigholi, H ; Tabeshpour, M. R ; Seif, M. S ; Sharif University of Technology
Taylor and Francis Ltd
2015
Abstract
In this article, wave endurance time (WET) is addressed as an applicable method for performance-based assessment of fixed offshore structures under extreme waves. In this method, inspired by the endurance time method in the field of earthquake engineering, artificial wave records called wave functions are designed so that their excitations gradually increase with time. Therefore, the main advantage of the proposed method is that it can assess the structural performance under various wave load conditions through a single time-history analysis. Moreover, the reliability of structures can be evaluated on the basis of the time that the structural response is still acceptable. In this study,...
Performance-based assessment of steel jacket platforms by wave endurance time method
, Article Ships and Offshore Structures ; Volume 12, Issue 1 , 2017 , Pages 32-42 ; 17445302 (ISSN) ; Dastan Diznab, M. A ; Mehdigholi, H ; Tabeshpour, M. R ; Seif, M. S ; Sharif University of Technology
2017
Abstract
In this article, wave endurance time (WET) is addressed as an applicable method for performance-based assessment of fixed offshore structures under extreme waves. In this method, inspired by the endurance time method in the field of earthquake engineering, artificial wave records called wave functions are designed so that their excitations gradually increase with time. Therefore, the main advantage of the proposed method is that it can assess the structural performance under various wave load conditions through a single time-history analysis. Moreover, the reliability of structures can be evaluated on the basis of the time that the structural response is still acceptable. In this study,...
Developing Dynamic Increasing Amplitude and Period (DIAP)Method for Evaluation of Offshore Structures
, M.Sc. Thesis Sharif University of Technology ; Tabeshpour, Mohammad Reza (Supervisor) ; Dastan Diznab, Mohammad Ali (Co-Advisor)
Abstract
In this study, Wave Endurance Time (WET) is introduced as an applicable method for assessment of offshore structures under extreme waves. In this method, artificial records called Wave Functions (WFs) are used instead of usual extreme wave records. WFs are designed so that their excitations gradually increase with time. Therefore, one WF can be replaced by a large number of sea surface records with different excitation levels. The main advantage of proposed method is that it assesses the structural performance under various extreme waves with low computational cost especially in comparison with three-hour simulasions. Moreover, reliability of structures can be evaluated based on the time...
Particulate 3D hydrogels of silk fibroin-pluronic to deliver curcumin for infection-free wound healing
, Article Biomimetics ; Volume 9, Issue 8 , 2024 ; 23137673 (ISSN) ; Johari, N ; Jahanmard, F ; Cecotto, L ; Khosravimelal, S ; Madaah Hosseini, H. R ; Bagheri, R ; Samadikuchaksaraei, A ; Amin Yavari, S ; Sharif University of Technology
2024
Abstract
Skin is the largest protective tissue of the body and is at risk of damage. Hence, the design and development of wound dressing materials is key for tissue repair and regeneration. Although silk fibroin is a known biopolymer in tissue engineering, its degradation rate is not correlated with wound closure rate. To address this disadvantage, we mimicked the hierarchical structure of skin and also provided antibacterial properties; a hydrogel with globular structure consisting of silk fibroin, pluronic F127, and curcumin was developed. In this regard, the effect of pluronic and curcumin on the structural and mechanical properties of the hydrogel was studied. The results showed that curcumin...
NIR emitting platinum pincer complexes based on the N^N^C ligand containing {benz[4,5]imidazo[1,2-a]pyrazin} aromatic system; synthesis, characterization and photophysical study
, Article Inorganica Chimica Acta ; Volume 511 , 2020 ; Hendi, Z ; Zhukovsky, D. D ; Sokolov, V. V ; Jamali, S ; Pavlovskiy, V. V ; Porsev, V. V ; Evarestov, R. A ; Tunik, S. P ; Sharif University of Technology
Elsevier S.A
2020
Abstract
In the present work we obtained a series of NIR luminescent platinum(II) complexes with a pincer N^N^C ligand based on the conjugated {benzoimidazo[1,2-a]pyrazine} system with the [Pt(N^N^C)L]n+ structural motif (L = phosphine, alkynyl or pyridine-type ligands). We have also synthesized two complexes with bidentate phosphines that demonstrate different types of coordination: 1) as chelating ligand (in case of 1,2-bis(diphenylphosphino)benzene), that led to de-coordination of pyridine ring of N^N^C ligand and formation of a [Pt(N^C)dppb]+ complex; 2) as a bridging ligand (in case of bis(diphenylphosphino)methane) between two {Pt(N^N^C)} fragments in a dimeric complex of type...
Targeted synthesis of NIR luminescent rhenium diimine cis,trans-[Re(NN)(CO)2(L)2]n+ complexes containing N-Donor axial ligands: photophysical, electrochemical, and theoretical studies
, Article ChemPlusChem ; Volume 85, Issue 11 , 2020 , Pages 2518-2527 ; Nayeri, S ; Jamali, S ; Porsev, V. V ; Gurzhiy, V. V ; Levin, O. V ; Koshevoy, I. O ; Tunik, S. P ; Sharif University of Technology
Wiley-VCH Verlag
2020
Abstract
The combined action of ultraviolet irradiation and microwave heating onto acetonitrile solution of [Re((Formula presented.))(CO)3(NCMe)]OTf ((Formula presented.) =phenantroline and neocuproine) afforded cis,trans-Re((Formula presented.))(CO)2(NCMe)2]+ acetonitrile derivatives. Substitution of relatively labile NCMe with a series of aromatic N-donor ligands (pyridine, pyrazine, 4,4’-bipyridine, N-methyl-4,4’-bipyridine) gave a novel family of the diimine cis,trans-[Re((Formula presented.))(CO)2(L)2]+ complexes. Photophysical studies of the obtained compounds in solution revealed unusually high absorption across the visible region and NIR phosphorescence with emission band maxima ranging from...
Spectra of Deza graphs
, Article Linear and Multilinear Algebra ; 2020 ; Ghodrati, A. H ; Hosseinzadeh, M. A ; Kabanov, V. V ; Konstantinova, E. V ; Shalaginov, L. V ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
A Deza graph with parameters (n, k, b, a) is a k-regular graph with n vertices such that any two of its vertices have b or a common neighbours, where b ≥ a. In this paper we investigate spectra of Deza graphs. In particular, using the eigenvalues of a Deza graph we determine the eigenvalues of its children. Divisible design graphs are significant cases of Deza graphs. Sufficient conditions for Deza graphs to be divisible design graphs are given, a few families of divisible design graphs are presented and their properties are studied. Our special attention goes to the invertibility of the adjacency matrices of Deza graphs. © 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group
Spectra of deza graphs
, Article Linear and Multilinear Algebra ; Volume 70, Issue 2 , 2022 , Pages 310-321 ; 03081087 (ISSN) ; Ghodrati, A. H ; Hosseinzadeh, M. A ; Kabanov, V. V ; Konstantinova, E. V ; Shalaginov, L. V ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
A Deza graph with parameters (Formula presented.) is a k-regular graph with n vertices such that any two of its vertices have b or a common neighbours, where (Formula presented.). In this paper we investigate spectra of Deza graphs. In particular, using the eigenvalues of a Deza graph we determine the eigenvalues of its children. Divisible design graphs are significant cases of Deza graphs. Sufficient conditions for Deza graphs to be divisible design graphs are given, a few families of divisible design graphs are presented and their properties are studied. Our special attention goes to the invertibility of the adjacency matrices of Deza graphs. © 2020 Informa UK Limited, trading as Taylor &...
Adsorption of proteins at the solution/air interface influenced by added nonionic surfactants at very low concentrations for both components. 3. dilational surface rheology
, Article Journal of Physical Chemistry B ; Volume 119, Issue 9 , January , 2015 , Pages 3768-3775 ; 15206106 (ISSN) ; Aksenenko, E. V ; Lylyk, S. V ; Lotfi, M ; Miller, R ; Sharif University of Technology
2015
Abstract
The influence of the addition of the nonionic surfactants C12 DMPO, C14 DMPO, C10 OH, and C10 EO5 at concentrations between 10-5 and 10-1 mmol/L to solutions of β-casein (BCS) and β-lactoglobulin (BLG) at a fixed concentration of 10-5 mmol/L on the dilational surface rheology is studied. A maximum in the viscoelasticity modulus |E| occurs at very low surfactant concentrations (10-4 to 10-3 mmol/L) for mixtures of BCS with C12 DMPO and C14 DMPO and for mixtures of BLG with C10 EO5 , while for mixture of BCS with C10 EO5 the value of |E| only slightly increased. The |E| values...
Treatment of beet sugar wastewater by UAFB bioprocess
, Article Bioresource Technology ; Volume 98, Issue 16 , 2007 , Pages 3080-3083 ; 09608524 (ISSN) ; Borghei, M ; Umrania, V. V ; Sharif University of Technology
2007
Abstract
The aim of this work was to study the treatment of strong beet sugar wastewater by an upflow anaerobic fixed bed (UAFB) at pilot plant scale. Three fixed bed bioreactors (each 60 L) were filled with standard industrial packing, inoculated with anaerobic culture (chicken manure, cow manure, anaerobic sludge digested from domestic wastewater) and operated at 32-34 °C with 20 h hydraulic retention time (HRT) and influent COD ranging between 2000-8000 mg/L. Under these conditions the maximum efficiency of organic content reduction in the reactor ranged from 75% to 93%. The reactor filled with standard pall rings made of polypropylene with an effective surface area of 206 m2/m3 performed best in...
GHZ states as near-optimal states for reference frame alignment
, Article Quantum Information Processing ; Volume 20, Issue 10 , 2021 ; 15700755 (ISSN) ; Jannesary, V ; Karimipour, V ; Sharif University of Technology
Springer
2021
Abstract
Let two coordinate systems, in possession of Alice and Bob, be related to each other by an unknown rotation R∈ SO (3). Alice is to send identical states | ψ⟩ to Bob who will make measurements on the received state and will determine the rotation R. The task of Bob is to estimate these parameters of the rotation R by the best possible measurements. Based on the quantum Fisher information, we show that Greenberger–Horne–Zeilinger (GHZ) states are near optimal states for this task. We show concrete measurements which will allow Bob to determine the rotation R. This shows that GHZ states, as superposition of macroscopically distinct states, are useful in yet another context in quantum...
Spectra of strongly Deza graphs
, Article Discrete Mathematics ; Volume 344, Issue 12 , 2021 ; 0012365X (ISSN) ; Haemers, W. H ; Hosseinzadeh, M. A ; Kabanov, V. V ; Konstantinova, E. V ; Shalaginov, L ; Sharif University of Technology
Elsevier B.V
2021
Abstract
A Deza graph G with parameters (n,k,b,a) is a k-regular graph with n vertices such that any two distinct vertices have b or a common neighbours. The children GA and GB of a Deza graph G are defined on the vertex set of G such that every two distinct vertices are adjacent in GA or GB if and only if they have a or b common neighbours, respectively. A strongly Deza graph is a Deza graph with strongly regular children. In this paper we give a spectral characterisation of strongly Deza graphs, show relationships between eigenvalues, and study strongly Deza graphs which are distance-regular. © 2021 Elsevier B.V
Spectra of strongly Deza graphs
, Article Discrete Mathematics ; Volume 344, Issue 12 , 2021 ; 0012365X (ISSN) ; Haemers, W. H ; Hosseinzadeh, M. A ; Kabanov, V. V ; Konstantinova, E. V ; Shalaginov, L ; Sharif University of Technology
Elsevier B.V
2021
Abstract
A Deza graph G with parameters (n,k,b,a) is a k-regular graph with n vertices such that any two distinct vertices have b or a common neighbours. The children GA and GB of a Deza graph G are defined on the vertex set of G such that every two distinct vertices are adjacent in GA or GB if and only if they have a or b common neighbours, respectively. A strongly Deza graph is a Deza graph with strongly regular children. In this paper we give a spectral characterisation of strongly Deza graphs, show relationships between eigenvalues, and study strongly Deza graphs which are distance-regular. © 2021 Elsevier B.V
The tendency towards equalization of the 234U/238U isotopic activity ratios in fractions of U(IV) and U(VI) during thermal annealing of metamict polycrase
, Article Applied Geochemistry ; Volume 161 , 2024 ; 08832927 (ISSN) ; Bogdanov, R. V ; Titov, A. V ; Fomin, E. V ; Samadfam, M ; Outokesh, M ; Sharif university of Technology
2024
Abstract
The fate of the immobilized actinides of the spent nuclear fuel in mineral-like matrices can be predicted by studying the behavior of uranium isotopes as representatives of the actinides in natural analogues. This work deals with the thermochemical behavior of uranium isotopes, which is accompanied by a redox process within the 25–800 °C temperature range in the metamict natural analogue of polycrase. The pattern of the changes in the relative contents of the U(IV) and U(VI) fractions at various temperatures was determined by a radiochemical analysis. The accuracy of the U(IV) and U(VI) values using the method of the chemical shift of the energy on the Lα1 X-ray emission line was verified....
Pyridinium salts - Versatile reagents for the regioselective synthesis of functionalized thiazocino[2,3-b]indoles by tandem dinucleophilic reactions of thiooxindoles
, Article Tetrahedron ; Volume 68, Issue 47 , 2012 , Pages 9685-9693 ; 00404020 (ISSN) ; Moghaddam, F. M ; Gormay, P. V ; Semeniuchenko, V ; Villinger, A ; Langer, P ; Iaroshenko, V. O ; Sharif University of Technology
2012
Abstract
The reaction of thiooxindoles with various 2- and 3-substituted pyridinium salts afforded a variety of functionalized thiazocinoindoles. The products have been prepared in good to excellent yields by regioselective dinucleophilic C/S-cyclocondensation of thiooxindoles with pyridinium salts