Search for: biomimetic-material
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    Fundamental differences of substrate hydroxylation by high-valent Lron(IV)-Oxo models of cytochrome P450

    , Article Inorganic Chemistry ; Volume 48, Issue 14 , 2009 , Pages 6661-6669 ; 00201669 (ISSN) Tahsini, L ; Bagherzadeh, M ; Nam, W ; De Visser, S. P ; Sharif University of Technology
    An Iron(lV)-oxo heme(+·) complex (Compound I, Cpd I) is the proposed active species of heme enzymes such as the cytochromes P450 and Is elusive; therefore, biomimetic studies on active site mimics give valuable Insight Into the fundamental properties of heme active species. In this work we present density functional theory (DFT) calculations on substrate hydroxylatlon by a Compound I mimic [FeIV=O(Por+̇)Cl] and its one-electron reduced form [FeIV=O(Por)Cl]-. Thus, recent experimental studies showed that [FeIV =O(Por)Cl]- is able to react with substrates via hydride transfer reactions [Jeong, Y. J.; Kang, Y.; Han, A.-R.; Lee, Y.-M.; Kotani, H.; Fukuzumi, S.; Nam, W. Angew. Chem., Int. Ed.... 

    Single and double stage sintering of mechanically alloyed powder for nanostructured Ti6Al4V foams usable in cancellous scaffolds

    , Article International Heat Treatment and Surface Engineering ; Volume 7, Issue 1 , 2013 , Pages 43-48 ; 17495148 (ISSN) Sadrnezhaad, S. K ; Aryana, M ; Hassanzadeh Nemati, N ; Alizadeh, M ; Ebadifar, A ; Sharif University of Technology
    Mechanical alloying and sintering were used to fabricate nanostructured Ti6Al4V scaffolds of highly controllable pore geometry and fully interconnected porous network. Elemental powders were milled for different periods of time (10, 20, 30, 40 and 60 h), mixed with 40-60 vol.-% of 200-400 μm cuboidal NaCl, compacted at 500-600 MPa and sintered according to single or double stage heat treatment regimes at 790 and 950°C under vacuum. After sintering, the samples were soaked in distilled water to washout the NaCl. Foamy microstructures were obtained showing well shaped biopores and fragmentary embedded micropores. The shape of initial NaCl was copied into the biopores which had highly... 

    Reactivity studies of biomimetic catalytic epoxidation of alkenes with tetrabutylammonium periodate in the presence of various manganese porphyrins and nitrogen donors: Significant axial ligand π-bonding effects

    , Article New Journal of Chemistry ; Volume 28, Issue 6 , 2004 , Pages 740-747 ; 11440546 (ISSN) Mohajer, D ; Karimipour, G ; Bagherzadeh, M ; Sharif University of Technology
    Royal Society of Chemistry  2004
    Highly selective epoxidation (> 95%) of unfunctionalized alkenes was performed by tetrabutylammonium periodate in the presence of six different phenyl substituted manganese(III) meso-tetraphenylporphyrins [Mn(Por)] and imidazole in CH2Cl2. Electron-withdrawing and bulky substituents on the phenyl groups lowered the catalytic activities of the corresponding Mn(Por). Less bulky alkenes with electron -rich double bonds showed greater reactivity in the epoxidation. Co-catalytic activities of four different classes of axial nitrogen donors are compared in the presence of various Mn(Por). In general no direct correlation was found between co-catalytic activities and the pKa values of the nitrogen... 

    A numerical approach to study the post-yield softening in cellular solids: role of microstructural ordering and cell size distribution

    , Article Acta Mechanica ; Volume 228, Issue 6 , 2017 , Pages 2005-2016 ; 00015970 (ISSN) Goodarzi Hosseinabadi, H ; Bagheri, R ; Altstadt, V ; Sharif University of Technology
    Springer-Verlag Wien  2017
    Designing meta-materials and cellular solids with biomimetic structures has received increasing attention in the past few years partially due to advances in additive manufacturing techniques that have enabled the fabrication of advanced materials with arbitrarily complex microarchitectures and novel functionalities. To impact on this trend, it is essential to develop our understanding about the role of microstructure on mechanical responses of these structures. Although a large literature exists on the general subject, the role of microstructure on the post-yield instability is not yet adequately documented. This research introduces a numerical approach to study the post-yield instability in... 

    Densification behavior and mechanical properties of biomimetic apatite nanocrystals

    , Article Current Nanoscience ; Volume 7, Issue 5 , 2011 , Pages 776-780 ; 15734137 (ISSN) Eskandari, A ; Aminzare, M ; Hassani, H ; Barounian, H ; Hesaraki, S ; Sadrnezhaad, S. K ; Sharif University of Technology
    Nanocrystalline hydroxyapatite (nHA) of 50 nm average diameter and length to diameter ratio of >3 was synthesized by biomimetic method. Non-isothermal sintering improved densification behavior and mechanical properties of apatite to 0.88 maximum fractional density, 70MPa bending strength, 148MPa compressive strength and 2.53GPa microhardness at sintering temperature of 1250°C. Higher sintering temperatures resulted in the decomposition of the apatite and in-situ biphasic calcium phosphate HAP/TCP formation. This process lowered apatite densification and weakened mechanical properties of the sintered specimen. Transmission electron microscopy (TEM), x-ray diffraction (XRD) and field emission... 

    Bioinspired nanofiber scaffold for differentiating bone marrow-derived neural stem cells to oligodendrocyte-like cells: Design, fabrication, and characterization

    , Article International Journal of Nanomedicine ; Volume 15 , 2020 , Pages 3903-3920 Boroojeni, F. R ; Mashayekhan, S ; Abbaszadeh, H. A ; Ansarizadeh, M ; Khoramgah, M. S ; Rahimi Movaghar, V ; Sharif University of Technology
    Dove Medical Press Ltd  2020
    Background: Researchers are trying to study the mechanism of neural stem cells (NSCs) differentiation to oligodendrocyte-like cells (OLCs) as well as to enhance the selective differentiation of NSCs to oligodendrocytes. However, the limitation in nerve tissue acces-sibility to isolate the NSCs as well as their differentiation toward oligodendrocytes is still challenging. Purpose: In the present study, a hybrid polycaprolactone (PCL)-gelatin nanofiber scaffold mimicking the native extracellular matrix and axon morphology to direct the differentiation of bone marrow-derived NSCs to OLCs was introduced. Materials and Methods: In order to achieve a sustained release of T3, this factor was...