Search for: oligomers
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    Synthesis, structure characterization and study of a new molybdenum schiff base complex as an epoxidation catalyst with very high turnover numbers

    , Article Inorganic Chemistry Communications ; Volume 84 , 2017 , Pages 63-67 ; 13877003 (ISSN) Bagherzadeh, M ; Ataie, S ; Mahmoudi, H ; Janczak, J ; Sharif University of Technology
    The reaction between [MoO2(acac)2] and an ONO type Schiff-base ligand (L = 4-bromo-2-((2-hydroxy-5-methylphenylimino)methyl)phenol) resulted a new oligomer molybdenum complex ([MoO2(L)]n). The oligomer complex was characterized by elemental analysis, FT-IR, 1H and 13C NMR spectroscopies. A suitable single crystal of the complex was grown in DMSO and characterized by X-ray single crystal diffraction as monomer stabilized by one DMSO molecule, [MoO2L(DMSO)]. The [MoO2(L)]n complex was used as a catalyst in epoxidation of olefins. Besides the high activity and selectivity, very high turnover numbers were a remarkable advantage of the catalytic system. © 2017  

    Investigation of the fracture resistance in hoop wound composites modified with two different reactive oligomers

    , Article Materials and Design ; Volume 30, Issue 8 , 2009 , Pages 3048-3055 ; 02641275 (ISSN) Abadyan, M ; Bagheri, R ; Haddadpour, H ; Motamedi, P ; Sharif University of Technology
    Rubber modification of hoop filament wound epoxy composites was investigated using amine-terminated butadiene acrylonitrile (ATBN) and carboxyl-terminated butadiene acrylonitrile (CTBN) oligomers. Both mechanical and physical properties of modified composites were investigated and the morphology of the samples was studied via scanning electron microscopy. Results indicated that, when added to the epoxy matrix, ATBN effected a superior increase in toughness, yet a more severe decline in compressive and flexural strength, compared to CTBN. In contrast, in the case of composite samples, incorporation of ATBN led to more favorable mechanical properties, from the viewpoint of both toughness and... 

    Thermal conductivity of polyamide-6,6 in the vicinity of charged and uncharged graphene layers: A molecular dynamics analysis

    , Article Journal of Physical Chemistry C ; Volume 116, Issue 26 , May , 2012 , Pages 14115-14122 ; 19327447 (ISSN) Alaghemandi, M ; Gharib-Zahedi, M. R ; Spohr, E ; Böhm, M. C ; Sharif University of Technology
    The thermal conductivity (λ) of nanoconfined polyamide-6,6 (PA) oligomers in polymer-graphene nanocomposites has been investigated by reverse nonequilibrium molecular dynamics (RNEMD) simulations. The preferential alignment of the PA chains parallel to the graphene plane as well as their elongation implies that λ of the polymer in nanocomposites is larger than that in the neat polymer system. The ordering of the polymer phase is enhanced in an arrangement of charged graphene surfaces made of one layer with a charge deficit and one with a charge excess. The consequence of the enhanced polymer ordering as well as the denser packing is an increase in λ in the polymer network. Differences in the... 

    A high performance multi-walled carbon nanotube-supported palladium catalyst in selective hydrogenation of acetylene-ethylene mixtures

    , Article Applied Catalysis A: General ; Volume 399, Issue 1-2 , May , 2011 , Pages 184-190 ; 0926860X (ISSN) Bazzazzadegan, H ; Kazemeini, M ; Rashidi, A. M ; Sharif University of Technology
    In this research, a palladium nanocatalyst was synthesised over a multi-walled carbon nanotube (MWCNT) support and then applied for selective hydrogenation of acetylene in an ethylene-richflow stream. This material displayed a very promising selectivity toward ethylene production with increasing temperature, and also suppressed oligomer formation during acetylene hydrogenation. New operating conditions for selective hydrogenation of acetylene in an ethylene-richflow were introduced. This nanocatalyst gave a considerably higher yield, as high as 93%, than that previously obtained for ethylene production. It was postulated that the governing mechanism for acetylene hydrogenation over 0.5 wt.%... 

    Mathematical modeling of drug release from biodegradable polymeric microneedles

    , Article Bio-Design and Manufacturing ; Volume 2, Issue 2 , 2019 , Pages 96-107 ; 20965524 (ISSN) Chavoshi, S ; Rabiee, M ; Rafizadeh, M ; Rabiee, N ; Shamsabadi, A. S ; Bagherzadeh, M ; Salarian, R ; Tahriri, M ; Tayebi, L ; Sharif University of Technology
    Springer  2019
    Transdermal drug delivery systems have overcome many limitations of other drug administration routes, such as injection pain and first-pass metabolism following oral route, although transdermal drug delivery systems are limited to drugs with low molecular weight. Hence, new emerging technology allowing high molecular weight drug delivery across the skin—known as ‘microneedles’—has been developed, which creates microchannels that facilitate drug delivery. In this report, drug-loaded degradable conic microneedles are modeled to characterize the degradation rate and drug release profile. Since a lot of data are available for polylactic acid-co-glycolic acid (PLGA) degradation in the literature,... 

    Molecular dynamics simulation and MM-PBSA calculations of sickle cell hemoglobin in dimer form with Val, Trp, or Phe at the lateral contact

    , Article Journal of Physical Organic Chemistry ; Volume 23, Issue 9 , March , 2010 , Pages 866-877 ; 08943230 (ISSN) Abroshan, H ; Akbarzadeh, H ; Parsafar, G. A ; Sharif University of Technology
    As the delay time and hence nuclei formation play a crucial role in the pathophysiology of sickle cell disease, MD simulation and molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) calculations have been performed on three systems of hemoglobin; namely dimer of hemoglobin with valine (Hb S), tryptophan (Hbβ6W), and phenylalanine (Hbβ6F) at β6 position. The structural changes due to these aromatic substitutions are investigated. It is shown that β subunits have significant impact on the differences between a dimer and other crystal structures. Transition from a dimer to polymer for Hb S system affects the donor molecule more than that of the acceptor. In the case of donor and...