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    Optical concentration of gold nanoparticles as a new concept of analytical sensitivity

    , Article Instrumentation Science and Technology ; 2020 Vaziri Heshi, S ; Shokoufi, N ; Seyed Reihani, S. N ; Sharif University of Technology
    Bellwether Publishing, Ltd  2020
    Concentration procedures have always been implemented when trace analysis of compounds in real matrices is contemplated. A variety of concentration strategies have been reported aiming at decreasing the limits of detection (LODs). The optical concentration of the substance in solution is one of the novel concepts for the enhancement of the analytical sensitivity. In this study, the optical concentration has been measured by the trapping of gold nanoparticles ((Formula presented.) nm) dispersed in water at low-concentrations at the focal volume of the laser beam. The influence of factors such as the time of gold nanoparticle trapping, the size of the nanoparticles, the intensity of the laser... 

    Dynamics of membrane nanotubes coated with I-BAR

    , Article Scientific Reports ; Volume 6 , 2016 ; 20452322 (ISSN) Barooji, Y. F ; Rørvig Lund, A ; Semsey, S ; Seyed Reihani, S. N ; Bendix, P. M ; Sharif University of Technology
    Nature Publishing Group  2016
    Membrane deformation is a necessary step in a number of cellular processes such as filopodia and invadopodia formation and has been shown to involve membrane shaping proteins containing membrane binding domains from the IRSp53-MIM protein family. In reconstituted membranes the membrane shaping domains can efficiently deform negatively charged membranes into tubules without any other proteins present. Here, we show that the IM domain (also called I-BAR domain) from the protein ABBA, forms semi-flexible nanotubes protruding into Giant Unilamellar lipid Vesicles (GUVs). By simultaneous quantification of tube intensity and tubular shape we find both the diameter and stiffness of the nanotubes.... 

    Mechanical induced reaction in Al-CuO system for in-situ fabrication of Al based nanocomposites

    , Article Journal of Alloys and Compounds ; Volume 465, Issue 1-2 , 2008 , Pages 151-156 ; 09258388 (ISSN) Arami, H ; Simchi, A ; Seyed Reihani, S. M ; Sharif University of Technology
    Gradual chemical (displacement) reaction between CuO and Al powders during high-energy attrition milling under a high purity argon atmosphere was studied. Differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques were employed to study the solid-state reaction. It was shown that the solid-state reaction occurred during mechanical alloying (MA) and resulted in the dissolution of copper into the aluminum lattice and formation of nanometric alumina particles. The reinforcement particles were mostly distributed at the grain boundaries of Al matrix with an average crystallite size of about 50 nm. In DTA curve of the milled powders, a small... 

    Investigating the effect of rolling strain on fracture behavior of roll bonded Al6061 laminates under quasi-static and dynamic loading

    , Article Materials Science and Engineering A ; Volume 558 , 2012 , Pages 82-89 ; 09215093 (ISSN) Hosseini Monazzah, A ; Bagheri, R ; Seyed Reihani, S. M ; Sharif University of Technology
    Damage tolerance improvement has been reported by laminating aluminum alloys and composites by researchers. Three-layer laminates comprising Al6061 outer layers and Al1050 interlayer have been roll bonded in this research. While most of the works done have focused on fracture properties of roll bonded Al laminates in crack arrester geometry, this study explores their behavior in crack divider configuration. Rolling strain is varied to control the interfacial bonding in laminates. The fracture behavior of laminates and the constituent material was examined via three-point bending and impact tests. This study presents significant improvement in damage tolerance of laminates compared to their... 

    Investigation on friction stir lap welding of aluminium to aluminium clad steel sheets

    , Article Science and Technology of Welding and Joining ; Volume 17, Issue 3 , 2012 , Pages 231-236 ; 13621718 (ISSN) Movahedi, M ; Kokabi, A. H ; Seyed Reihani, S. M ; Sharif University of Technology
    In this work, the feasibility of friction stir lap welding an aluminium alloy (Al-5083) to the aluminium clad steel sheet was studied. The welded joints were characterised by various methods including shear-tensile test and optical microscopy and scanning electron microscopy. The results indicated that sound and defect free joints were obtained. The fracture loads of the samples reached up to 94% compared with that of the steel base metal. Moreover, the joint strength linearly increased with the decrease in thickness of the aluminium layer roll bonded on the steel sheet. It was also shown that welding rotation and travel speed variation did not considerably impact the fracture loads in the... 

    Investigation on the bond strength of Al-1100/St-12 roll bonded sheets, optimization and characterization

    , Article Materials and Design ; Volume 32, Issue 6 , 2011 , Pages 3143-3149 ; 02641275 (ISSN) Movahedi, M ; Kokabi, A. H ; Seyed Reihani, S. M ; Sharif University of Technology
    Al-1100/St-12 aluminum clad steel sheets were produced using roll bonding process at different reductions in thickness and with various supplemental annealing treatments. Experiments were conducted by applying the Taguchi method to obtain optimum condition for maximizing the joint strength. The joint strengths of the bi-layer sheets were evaluated by peel test. The Al/Fe intermetallic phases at the joint interface and the peeled surfaces were examined using scanning electron microscopy (SEM). Energy dispersive spectroscopy (EDS) and Vickers microhardness test were performed to characterize the intermetallic compounds. The results indicate that at the optimum condition of 0.50 reduction in... 

    Friction and wear performance of copper-graphite surface composites fabricated by friction stir processing (FSP)

    , Article Wear ; Volume 304, Issue 1-2 , 2013 , Pages 1-12 ; 00431648 (ISSN) Sarmadi, H ; Kokabi, A. H ; Seyed Reihani, S. M ; Sharif University of Technology
    Copper-graphite composites which have low friction coefficient can be used as bearing materials in lieu of materials containing lead which cause environmental problems. So far, some methods such as powder metallurgy and centrifugal casting have been employed to produce these composites. In this study, friction stir processing (FSP) was used to produce copper-graphite surface composites. Five tools with different pin profile were employed in order to achieve a comprehensive dispersion. Results show that the tool with triangular pin gives rise to a better dispersion of graphite particles. Furthermore, four copper-graphite composites containing different graphite content were prepared using... 

    Creep behavior of hot extruded Al-Al2O3 nanocomposite powder

    , Article Materials Science and Engineering A ; Volume 527, Issue 10-11 , 2010 , Pages 2567-2571 ; 09215093 (ISSN) Hosseini Monazzah, A ; Simchi, A ; Seyed Reihani, S. M ; Sharif University of Technology
    A commercial gas-atomized aluminum powder was mechanically milled in a planetary ball mill under an argon atmosphere for 12 h to produce alumina dispersion strengthened aluminum powder. Transmission electron microscopy (TEM) revealed that about 2 vol.% alumina particles with an average size of 100 nm were distributed in the aluminum matrix. The nanocomposite powder was canned in an aluminum container, vacuum de-gassed, and hot extruded at 723 K at an extrusion ratio of 16:1. The creep behavior of the extruded billet in the direction of extrusion was examined at a constant applied load ranging from 10 to 40 MPa at temperatures of 648, 673 and 723 K. A threshold creep-stress was noticed which... 

    Creep behavior of hot extruded Al-5% SiC composite powder

    , Article 2006 Powder Metallurgy World Congress and Exhibition, PM 2006, Busan, 24 September 2006 through 28 September 2006 ; Volume 534-536, Issue PART 2 , 2007 , Pages 861-864 ; 02555476 (ISSN); 0878494197 (ISBN); 9780878494194 (ISBN) Hosseini Monnazah, A ; Simchi, A ; Seyed Reihani, S. M ; Sharif University of Technology
    Trans Tech Publications Ltd  2007
    The creep behavior of particulate Al-5vol.% SiC composite was investigated. The composite powder was produced by mechanical milling and hot extruded at 450°C at the ratio of 16:1. A creep test was carried out at a constant load at 598, 648, and 673 K. Using the existing equations proposed for the steady-state creep of metals, the threshold stress and the stress exponent of the creep as a function of temperature were determined. The stress exponent was found to be 3 at the temperature of 673 K and 8 at the lower temperatures, i.e. 598 and 648 K. The dependency of the threshold stress to temperature obeys the Arrhenius relationship with the energy term of 29 kJ mole-1  

    Study of the compaction behavior of composite powders under monotonic and cyclic loading

    , Article Composites Science and Technology ; Volume 65, Issue 14 , 2005 , Pages 2094-2104 ; 02663538 (ISSN) Tavakoli, A. H ; Simchi, A ; Seyed Reihani, S. M ; Sharif University of Technology
    The consolidation behavior of composite powders during pressure cycling at room temperature in uniaxial compaction experiments was studied and compared with monotonic compaction. Aluminum and various amounts of SiC powders (up to 50 vol%) were used to investigate the effect of hard reinforcement particle on the densification of soft aluminum matrix. The cyclic compaction was carried out at various pressure amplitudes, ranges from 90 to 360 MPa, at the frequency of 1 Hz. The pressure cycling was continued up to 5000 cycle, in which, the rate of consolidation was found to be fairly low. The consolidation of the composite powders under different loading modes was analyzed through... 

    Evaluation of Effective Parameters in Trapping Aerosols and Examination of Possibility of Detecting Distortions of Microdroplets by Means of Optical Tweezer

    , M.Sc. Thesis Sharif University of Technology Khajeh, Ahmad (Author) ; Seyed Reihani, Nader (Supervisor)
    Optical tweezer is a highly focused laser beam that could be used to trap micro and nano particles in three dimensions. It could be used to measure(or apply) piconewton range forces. Most of the optical tweezers experiments have been done in liquid mediums. In last few years, trapping particles which are floating in gas mediums(called aerosols) have been considered extensively. In this thesis, the changes in trap stiffness and conversion factor due to changes in laser power, trapping depth and particle are evaluated. It is shown that changing these three parameters, cause considerable changes in trap stiffnes and conversion factor. Linear behavior of trap stiffness versus laser power,... 

    Investigation of deformation mechanism in polypropylene/glass fiber composite

    , Article Journal of Applied Polymer Science ; Volume 87, Issue 13 , 2003 , Pages 2171-2176 ; 00218995 (ISSN) Zebarjad, S. M ; Bagheri, R ; Seyed Reihani, S. M ; Forunchi, M ; Sharif University of Technology
    A great amount of work has been done over the past few years to understand the structure-properties relationship in polypropylene/glass fiber composites. This is because of the very fast-growing rate of polypropylene applications in the automotive and other industries. This work focused on the role of glass fibers and fiber-matrix adhesion on deformation mechanism. Composites with different fiber content, with and without adhesion promoter, were fabricated. Tensile tests and microscopy techniques were conducted. Based on the results, a physical model has been proposed that illustrates the initiation and growth of the damage under static loading condition. According to this work, the... 

    Deformation, Yield and fracture of elastomer-modified polypropylene

    , Article Journal of Applied Polymer Science ; Volume 90, Issue 14 , 2003 , Pages 3767-3779 ; 00218995 (ISSN) Zebarjad, S. M ; Bagheri, R ; Seyed Reihani, S. M ; Lazzeri, A ; Sharif University of Technology
    In recent decades, great attention has been devoted to the toughening of isotactic poly(propylene) (PP) with elastomers such as ethylene-propylene rubber (EPR). The most important reasons for this interest are the moderate cost and favorable properties of PP. This article is focused on the role of EPR in the deformation and fracture mechanism of PP/EPR blends with different volume fractions of elastomer phase. Differential scanning calorimetry (DSC), tensile tests, and microscopy techniques were used in this study. The fracture mechanism of isotactic PP toughened by EPR (PP/EPR) has also been studied by three point bending (3-PB) and four point bending (4-PB) tests. Rubber particle... 

    Architecturally modified Al-DRA composites: The effect of size and shape of the DRA rods on fracture behavior

    , Article Journal of Materials Science ; Volume 45, Issue 11 , June , 2010 , Pages 2852-2861 ; 00222461 (ISSN) Jamali, M ; Farokhzadeh, K ; Bagheri, R ; Seyed Reihani, S. M ; Sharif University of Technology
    Architectural modification of aluminum matrix composites is considered as an efficient method to improve fracture toughness. Al-DRA (Al-Al/SiC/20 p) composites were fabricated via "powder extrusion-casting- ingot extrusion" route with structures similar to that of reinforced concrete, so that DRA rods were surrounded by unreinforced aluminum. The effects of variation in shape, size, and number of DRA rods on fracture behavior of Al-DRA composites were investigated. Composites containing DRA rods with hexagonal cross-section exhibited higher resistance to crack initiation and growth, in comparison to those containing circular rods. In the case of hexagonal rods, increasing the number of rods... 

    Effect of nanoscaled reinforcement particles on the structural evolution of aluminium powder during mechanical milling

    , Article Powder Metallurgy ; Volume 52, Issue 2 , 2009 , Pages 151-157 ; 00325899 (ISSN) Razavi Hesabi, Z ; Kamrani, S ; Simchi, A ; seyed Reihani, M ; Sharif University of Technology
    This paper presents experimental results on the synthesis of nanostructured aluminium matrix nanocomposite powders by comilling of nanoscaled SiC and Al2O3 particles and micrometric aluminium powder. The effect of the nanometric reinforcement particles on the mechanical milling (MA) process of the soft matrix was studied by scanning electron microscopy, X-ray diffraction (XRD), transmission electron microscopy, laser particle size analyser and standard metallographic techniques. It was found that at the early stage of milling, the nanoparticles are smeared on the surface of the aluminium powder and thus do not significantly contribute in the MA process. As the milling continues, the hard... 

    Iron-borosilicate soft magnetic composites: the correlation between processing parameters and magnetic properties for high frequency applications

    , Article Journal of Magnetism and Magnetic Materials ; Volume 429 , 2017 , Pages 241-250 ; 03048853 (ISSN) Gheiratmand, T ; Madaah Hosseini, H .R ; Seyed Reihani, S. M ; Sharif University of Technology
    Elsevier B.V  2017
    Iron-borosilicate soft magnetic composites are suitable magnetic materials for high temperature and high frequency applications. In this research two different techniques have been applied to fabricate these composites: uniaxial pressing following by sintering and spark plasma sintering. Different processing parameters including the content of borosilicate, the amount of compaction pressure and the size of iron particles have been evaluated through the study of microstructure and magnetic properties. The microstructural observations showed that the borosilicate is distributed on the iron grain boundaries enhancing the resistivity and causing the loss of eddy currents. Increasing the... 

    Effect of reinforcement volume fraction on mechanical alloying of Al-SiC nanocomposite powders

    , Article Powder Metallurgy ; Volume 50, Issue 3 , 2007 , Pages 276-282 ; 00325899 (ISSN) Kamrani, S ; Simchi, A ; Riedel, R ; Seyed Reihani, S. M ; Sharif University of Technology
    Mixtures of aluminium powder and nanoscaled SiC particles (n-SiC) at various volume fractions of 0, 1, 3, 5, 7 and 10 are comilled in a high energy planetary ball mill under an argon atmosphere to produce nanocrystalline Al-SiC nanocomposites. High resolution scanning electron microscopy (HRSEM), X-ray diffraction (XRD) method, laser particle size analysis and powder density measurement were used to study the morphological changes and microstructural evolution occurred during mechanical alloying. Al-SiC composite powder with microscaled SiC particles (1 μm) was also synthesised and characterised to examine the influence of reinforcement particle size on the milling process. It was found that... 

    Designing and Developing an Active Micromixer Based on Optical Tweezers for Microfluidics

    , M.Sc. Thesis Sharif University of Technology Taheri, Saeed (Author) ; Seyed Reihani, Nader (Supervisor)
    Microfluidics is a field of science that studies micron-scale characteristics of fluids. In this scale fluids show fascinating behavior far beyond our expectation compared to their large-scale counterparts. One of such peculiar behavior is the mixing of two different liquids flowing inside a microchannel. Due to low Reynolds number, the flow inside such a channel would be dominated by laminar behavior. In this regime mixing of the fluids is only mediated by molecular diffusion which is a rather slow process. In the current thesis, we utilized the rotating ability of optical tweezers to construct an active micromixer for Microfluidics. In order to do this we used birefringent microbeads. The... 

    Laser-Based Surface Tension Measurement

    , M.Sc. Thesis Sharif University of Technology Amini, Mansoureh (Author) ; Seyed Reihani, Morteza (Supervisor)
    Surface tension is the most important interfacial parameter of a liquid. This quantity plays a key role in many processes such as extraction, distillation, absorption and chemical reactions. Various methods are proposed for measuring this quantity among which, the laser based methods are the most accurate ones. Unlike most of the mechanical methods, laser based methods remotely measure the surface tension. The aim of the current thesis is to measure the surface tension using laser beam, more specifically using homodyne detection system. This method implemented in both reflected and transmitted modes. In each of the mentioned methods, first the laser beam was incident to the liquid-air... 

    Creating Double Optical Trap Using Fresnel Lens

    , M.Sc. Thesis Sharif University of Technology Farajian, Mahboubeh (Author) ; Seyed Reihani, Nader (Supervisor)
    Intensity or phase Modulation of a wavefront is possible by means of optical devices. Placing a grating or lens on the way of a wavefront, will alter the phase or intensity of it and this will make a diffraction pattern. Spatial Light Modulator (SLM) is an optical device which is the most important part of a video projector. One can apply grating, lens and other phases on the wavefront using this device.In this project we used SLM to modify phase of laser beam and then we made many focal points such that they could displace independently. The result of this project can be used in designing and creating a holographic optical tweezers.Moreover, A. Einstein proved that the light could be...