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    Optimization of a vanillin assay for determination of anthocyanins using D-optimal design

    , Article Analytical Methods ; Volume 4, Issue 3 , Feb , 2012 , Pages 824-829 ; 17599660 (ISSN) Khoshayand, M. R ; Roohi, T ; Moghaddam, G ; Khoshayand, F ; Shahbazikhah, P ; Oveisi, M. R ; Hajimahmoodi, M ; Sharif University of Technology
    The vanillin assay is a spectrophotometric method for anthocyanin determination that is simple, quick and inexpensive. The method is preferred because of its high sensitivity, specificity and simplicity; however, the results of this test are influenced by several factors. Hence, a D-optimal experimental design approach was investigated to simultaneously, without loss of information, optimize five factors that influence the vanillin assay: acid normality, vanillin concentration, temperature, time and acid type. Further optimization with a D-optimal design and response surface analysis (RSM) showed that a second-order polynomial model fit the experimental data appropriately. The optimum... 

    Conformal invariance of isoheight lines in a two-dimensional Kardar-Parisi-Zhang surface

    , Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 77, Issue 5 , 2008 ; 15393755 (ISSN) Saberi, A. A ; Niry, M. D ; Fazeli, S. M ; Rahimi Tabar, M. R ; Rouhani, S ; Sharif University of Technology
    The statistics of isoheight lines in the (2+1) -dimensional Kardar-Parisi-Zhang (KPZ) model is shown to be conformally invariant and equivalent to those of self-avoiding random walks. This leads to a rich variety of exact analytical results for the KPZ dynamics. We present direct evidence that the isoheight lines can be described by the family of conformally invariant curves called Schramm-Loewner evolution (or SLEI) with diffusivity Î=8/3. It is shown that the absence of the nonlinear term in the KPZ equation will change the diffusivity I from 8/3 to 4, indicating that the isoheight lines of the Edwards-Wilkinson surface are also conformally invariant and belong to the universality class of... 

    Conformal curves on the WO3 surface

    , Article Physical Review Letters ; Volume 100, Issue 4 , 2008 ; 00319007 (ISSN) Saberi, A. A ; Rajabpour, M. A ; Rouhani, S ; Sharif University of Technology
    We have studied the isoheight lines on the WO3 surface as a physical candidate for conformally invariant curves. We have shown that these lines are conformally invariant with the same statistics of domain walls in the critical Ising model. They belong to the family of conformal invariant curves called Schramm-Loewner evolution (or SLEκ), with diffusivity of κ∼3. This can be regarded as the first experimental observation of SLE curves. We have also argued that Ballistic Deposition (BD) can serve as a growth model giving rise to contours with similar statistics at large scales. © 2008 The American Physical Society  

    Microstructure-toughness relationship in AISI4340 steel

    , Article Defect and Diffusion Forum ; Volume 312-315 , 2011 , Pages 110-115 ; 10120386 (ISSN) ; 9783037851173 (ISBN) Saeidi, N ; Ekrami, A ; Sharif University of Technology
    To improve the strength and toughness of AISI 4340 steel, different microstructures, containing full bainite, bainite-ferrite, martensite-ferrite and full martensite were produced by different heat treatment cycles. Tensile, impact and hardness tests were carried out at room temperature. The ductile-brittle transition temperature was determined from impact data at different temperatures. The results showed that steel with bainite - 0.34 ferrite microstructure has the highest elongation and charpy impact energy, while its tensile strength and yield stress decreased in comparison to other microstructures. This increment was noticeable when bainite - 0.34 ferrite steel was tempered. The... 

    Characterization of nitrocarburized surface layer on AISI 1020 steel by electrolytic plasma processing in an urea electrolyte

    , Article Journal of Materials Research and Technology ; Volume 2, Issue 3 , 2013 , Pages 213-220 ; 22387854 (ISSN) Karimi Zarchi, M ; Shariat, M.H ; Dehghan, S. A ; Solhjoo, S ; Sharif University of Technology
    Elsevier Editora Ltda  2013
    In this study, electrolytic plasma processing (EPP) was employed for surface nitrocarburizing of AISI 1020 steel in a urea electrolyte, where the substrate samples were connected cathodically to a high-voltage DC current power supply. The structural, mechanical, wear and corrosion properties of the samples treated for 3-5 min were investigated. The results show that the surface layers formed on the samples by this treatment at 220 V have a ferritic nitrocarburizing characteristic which consists of a compound layer and diffusion zone. The surface layers of the treated samples at 240 V consisted of a compound layer, martensitic layer and diffusion zone, respectively, which is a marker of... 

    Impact properties of tempered bainite-ferrite dual phase steels

    , Article Materials Science and Engineering A ; Volume 527, Issue 21-22 , August , 2010 , Pages 5575-5581 ; 09215093 (ISSN) Saeidi, N ; Ekrami, A ; Sharif University of Technology
    To improve both strength and toughness of AISI 4340 steel three microstructures, full bainite, bainite-ferrite and tempered bainite-ferrite, were produced by heat treatment of this steel. Tensile, impact and hardness properties of these microstructures were compared. The results showed that with tempering of bainite-34% ferrite dual phase steel, elongation and charpy impact energy increased significantly in comparison to bainite and bainite-ferrite microstructures. Also ductile-brittle transition temperatures of bainite-ferrite and tempered bainite-ferrite steels were measured and confirmed superior toughness properties of this microstructure. Fracture surface analysis of charpy specimens... 

    Corrosion behaviour of Ni-Co alloy coatings at Kish Island (marine) atmosphere

    , Article Bulletin of Materials Science ; Vol. 37, issue. 3 , May , 2014 , p. 713-719 Sharifi, K ; Ghorbani, M ; Sharif University of Technology
    In this study, the corrosion behaviour of Ni-Co alloys with low Co content, electroplated on steel substrate in sulphate bath, was investigated. The morphology of coatings was studied by optical and SEM microscopy. The corrosion products were analyzed using EDX. The results showed that Ni-1%Co coatings had a better corrosion resistance 0.30, 0.92 and 3.75 mpy for atmospheric, salt spray and polarization tests, respectively. These are 0.41, 1.20 and 5.40 mpy for pure nickel coatings that indicate the least corrosion resistance. Surface analysis revealed the presence of oxides, sulphides and chlorides in corrosion products  

    Design methodology and preliminary sizing of an unmanned mars exploration plane (UMEP)

    , Article APPLIED MECHANICS AND MATERIALS; 332; 15; Biomechanics, neurorehabilitation, mechanical engineering, manufacturing systems, robotics and aerospace: optimization of the engineering systems; OPTIROB 2013 ; Volume 332 , 2013 , Pages 15-20 ; 16609336 (ISSN) ; 9783037857335 (ISBN) Behroo, M ; Banazadeh, A ; Golkhandan, A. R ; Sharif University of Technology
    This paper discusses the mission requirements and design constraints for an Unmanned Martian research aircraft based on a tailor-made classical airplane design methodology. First, the exploration mission is described using the information from previous real-world experiences and the desired payload is proposed accordingly. The environmental conditions that dictate severe constraints to the design space are characterized afterwards. The conventional airplane design cycle is modified to address the lack of statistical data and to define a proper design recycling criteria. Eventually, the outcome is presented in the form of a novel configuration that is well suited to carry out the specified... 

    A conceptual approach to improve configuration of a prolonged manned mission spacecraft based on DSM

    , Article Gain Competitive Advantage by Managing Complexity - Proceedings of the 14th International Dependency and Structure Modelling Conference, DSM 2012, 13 September 2012 through 14 September 2012 ; September , 2012 , Pages 463-472 ; 9783446433540 (ISBN) Malaek, S. M. B ; Zohrevandi, E ; Sharif University of Technology
    Institution of Engineering Designers  2012
    To increase crew efficiency during a long duration space mission, we have developed a Sequence Dependent Structured Matrix (SDSM) which enables designers to quickly derive the shortest paths astronauts (mission specialists) need to perform their daily tasks. This research aims to develop a new efficient tool by combining two or more DSM interpretations which help increase the ability of proper decision makings for complex situations as space travel. The results of this work have been used for arranging crew quarters in the spacecraft suited for Mars mission. In the same approach, we have been able to generalize the concept and construct different specific types of DSM; such as, Astronauts'... 

    Cooperative abnormality detection via diffusive molecular communications

    , Article IEEE Transactions on Nanobioscience ; Volume 16, Issue 8 , 2017 , Pages 828-842 ; 15361241 (ISSN) Mosayebi, R ; Jamali, V ; Ghoroghchian, N ; Schober, R ; Nasiri-Kenari, M ; Mehrabi, M ; Sharif University of Technology
    In this paper, we consider abnormality detection via diffusive molecular communications (MCs) for a network consisting of several sensors and a fusion center (FC). If a sensor detects an abnormality, it injects a number of molecules into the medium which is proportional to its sensing output. Two transmission schemes for releasing molecules into the medium are considered. In the first scheme, each sensor releases a different type of molecule (DTM), whereas in the second scheme, all sensors release the same type of molecule (STM). The molecules released by the sensors propagate through the MC channel and some may reach the FC where the final decision regarding whether or not an abnormality... 

    Statistical analysis for enzymatic decolorization of acid orange 7 by Coprinus cinereus peroxidase

    , Article International Biodeterioration and Biodegradation ; Volume 64, Issue 3 , 2010 , Pages 245-252 ; 09648305 (ISSN) Yousefi, V ; Kariminia, H. R ; Sharif University of Technology
    Enzymatic decolorization of the monoazo dye, acid orange 7 (AO7) by the fungal peroxidase from Coprinus cinereus NBRC 30628 is a complex system, which is greatly affected by temperature, pH, enzyme activity and the concentrations of H2O2 and dye concentration. The study of these factors and investigating the combined interactions between them by applying one-factor-at-a-time (OFAT) method and two other statistical methods including 2-factorial method and response surface methodology (RSM) were aimed in this work. Through OFAT analysis the optimized conditions were a temperature of 25 °C, pH 9.0 with H2O2 concentration of about 3.9 mM and AO7 concentration of 40 mg/l. A complete... 

    Studying the effect of kinematical pattern on the mechanical performance of paraplegic gait with reciprocating orthosis

    , Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 226, Issue 8 , 2012 , Pages 600-611 ; 09544119 (ISSN) Nakhaee, K ; Farahmand, F ; Salarieh, H ; Sharif University of Technology
    SAGE  2012
    Paraplegic users of mechanical walking orthoses, e.g. advanced reciprocating gait orthosis (ARGO), often face high energy expenditure and extreme upper body loading during locomotion. We studied the effect of kinematical pattern on the mechanical performance of paraplegic locomotion, in search for an improved gait pattern that leads to lower muscular efforts. A three-dimensional, four segment, six-degrees-of-freedom skeletal model of the advanced reciprocating gait orthosis-assisted paraplegic locomotion was developed based on the data acquired from an experimental study on a single subject. The effect of muscles was represented by ideal joint torque generators. A response surface analysis... 

    Development of plasma and/or chemically induced graft co-polymerized electrospun poly(vinylidene fluoride) membranes for solute separation

    , Article Separation and Purification Technology ; Volume 108 , 2013 , Pages 196-204 ; 13835866 (ISSN) Savoji, H ; Rana, D ; Matsuura, T ; Tabe, S ; Feng, C ; Sharif University of Technology
    Nanofiber membranes were fabricated by electrospinning poly(vinylidene fluoride). The electrospun nanofiber membranes were further modified by grafting of acrylic acid (AA) and methacrylic acid (MAA) over the surfaces of the membranes. Plasma AA graft was attempted only, and the results indicated the partial membrane pore filling with grafted AA. For MAA grafting, chemically induced polymerization using benzoyl peroxide and hydrogen peroxide was attempted. The combination of plasma and chemically induced MAA graft polymerization was also attempted. The membranes were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and static contact angle (SCA)... 

    Design and operation of a double-fiber scanning system for surface profiling

    , Article Optics and Lasers in Engineering ; Volume 49, Issue 8 , 2011 , Pages 1032-1039 ; 01438166 (ISSN) Golnabi, H ; Sharif University of Technology
    Design and operation of an opto-mechanical system for surface profiling are reported in this study. The reported system consists of a double-fiber optical design and an electro-mechanical scanning system. In this arrangement one fiber transmits the source light to the object surface and the second one transmits the light reflected off the surface to a photodetector. By scanning the double-fiber assembly in one-direction, reflection properties of different curved surfaces are investigated. Reflection signals for the cylindrical surfaces made with different curvatures and materials are reported. In order to see the effect of the surface material, for a fixed radius cylinder, the surface is... 

    How morphological surface parameters are correlated with electrocatalytic performance of cobalt-based nanostructures

    , Article Journal of Industrial and Engineering Chemistry ; Volume 57 , 2018 , Pages 97-103 ; 1226086X (ISSN) Naseri, N ; Talu, S ; Kulesza, S ; Qarechalloo, S ; Achour, A ; Bramowicz, M ; Ghaderi, A ; Solaymani, S ; Sharif University of Technology
    Korean Society of Industrial Engineering Chemistry  2018
    To overcome recent energy and environment challenges, developing efficient and low cost photocatalysts are unavoidable. In this context, design of semiconductor nanostructures modified with earth abundant co-catalysts for water splitting reactions requires well engineered and controlled process to optimize surface interface and maximize nanocomposite system efficiency. Here, TiO2 nanotube were synthesized electrochemically and decorated with cobalt based nanostructure co-catalyst for water oxidation reaction using low cost and scalable electro-deposition approach. By changing deposition parameters and complete studying on samples surface morphology and related statistical analysis data,... 

    Physical bounds of metallic nanofingers obtained by mechano-chemical atomic force microscope nanolithography

    , Article Applied Surface Science ; Volume 255, Issue 6 , January , 2009 , Pages 3513-3517 ; 01694332 (ISSN) Akhavan, O ; Abdolahad, M ; Sharif University of Technology
    To obtain metallic nanofingers applicable in surface acoustic wave (SAW) sensors, a mechano-chemical atomic force microscope (AFM) nanolithography on a metallic thin film (50 nm in thickness)/piezoelectric substrate covered by a spin-coated polymeric mask layer (50-60 nm in thickness) was implemented. The effective shape of cross-section of the before and after etching grooves have been determined by using the AFM tip deconvolution surface analysis, structure factor, and power spectral density analyses. The wet-etching process improved the shape and aspect ratio (height/width) of the grooves and also smoothed the surface within them. We have shown that the relaxed surface tension of the... 

    On the power-bandwidth trade-off in bistable photonic switches

    , Article Photonic and Phononic Crystal Materials and Devices IX, San Jose, CA, 27 January 2009 through 29 January 2009 ; Volume 7223 , 2009 ; 0277786X (ISSN) Naqavi, A ; Abediasl, H ; Mehrany, K ; Khorasani, S ; Chamanzar, M. R ; Adibi, A ; Sharif University of Technology
    Low power operation and high speed have always been desirable in applications such as data processing and telecommunications. While achieving these two goals simultaneously, however, one encounters the well-known powerbandwidth trade-off. This is here discussed in a typical bistable switch based on a two-dimensional photonic crystal with Kerr type nonlinearity. The discussion is supported by the nonlinear finite difference time domain (FDTD) simulation of a direct coupled structure with a home-developed code. Two cases of working near resonant and off- resonant are simulated to compare the power and the speed of the device in the two cases. It is shown that working nearresonance reduces the... 

    Mechano-chemical AFM nanolithography of metallic thin films: A statistical analysis

    , Article Current Applied Physics ; Volume 10, Issue 4 , 2010 , Pages 1203-1210 ; 15671739 (ISSN) Akhavan, O ; Abdolahad, M ; Sharif University of Technology
    A mechano-chemical atomic force microscope (AFM) nanolithography on a metallic thin film (50 nm in thickness) covered by a spin-coated soft polymeric mask layer (50-60 nm in thickness) has been introduced. The surface stochastic properties of initial grooves mechanically patterned on the mask layer (grooves before chemical wet-etching) and the lithographed patterns on the metallic thin film (the grooves after chemical wet-etching) have been investigated and compared by using the structure factor, power spectral density, and AFM tip deconvolution analyses. The effective shape of cross section of the before and after etching grooves have been determined by using the tip deconvolution surface... 

    AFM stochastic analysis of surface twisted nanograin chains of iron oxide: a kinetic study

    , Article Journal of Physics D: Applied Physics ; Volume 42, Issue 6 , 2009 ; 00223727 (ISSN) Akhavan, O ; Azimirad, R ; Sharif University of Technology
    We have studied the stochastic parameters of surface iron oxide nanograin chains, 97 nm in diameter and 2.4 νm in length, prepared at different annealing temperatures, using atomic force microscopy (AFM) spectral analysis. In this regard, the roughness of the thin films including self-assembled twisted nanograin chains has been analysed and characterized using the height-height correlation function, the roughness exponent as well as the power spectrum density of the AFM profiles and their gradient, for the different annealing temperatures. The tip convolution effect on the stochastic parameters under study has also been investigated. The kinetics of the formation of nanograins on the film... 

    Preparation and investigations on the thermal, structural and magnetic behavior of Co-Ce substituted Ni nanoferrites

    , Article Materials Research Express ; Volume 6, Issue 11 , 2019 ; 20531591 (ISSN) Qamar, S ; Yasin, S ; Ramzan, N ; Iqbal, T ; Niaz Akhtar, M ; Sharif University of Technology
    Institute of Physics Publishing  2019
    Co-Ce doped Ni nanocrystalline ferrites having composition Ni0.8Ce0.2CoxFe2-xO4 with x = 0.00, 0.25, 0.50, 0.75, 1.00 were fabricated by sol gel auto combustion method. Synthesized samples were investigated by thermal gravimetric and differential thermal analysis (TGA-DTA), Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis (EDX) and vibrating sample magnetometer (VSM) to study the phase, vibrational modes, structure, surface analysis and magnetic properties respectively. Structural parameters (lattice parameters, cell volume, crystallite size and micro strains) were also calculated from XRD recorded data....