Search for: enamels
0.006 seconds
Total 39 records

    Comparative assessment of the crystalline structures of powder and bulk human dental enamel by X-ray diffraction analysis

    , Article Journal of Oral Biosciences ; Volume 61, Issue 3 , 2019 , Pages 173-178 ; 13490079 (ISSN) Behroozibakhsh, M ; Hajizamani, H ; Shekofteh, K ; Otadi, M ; Ghavami Lahiji, M ; Faal Nazari, N. S ; Sharif University of Technology
    Japanese Association for Oral Biology  2019
    Objectives: The aim of this study was to assess and compare the crystalline structures of both powder and bulk human dental enamel by X-ray diffraction analysis (XRD). Methods: The buccal surfaces of 60 selected noncarious third molars were divided into two groups of powdered and bulk enamel specimens. To prepare enamel powders, the enamel tissues were ground and powdered manually using a mortar and pestle. For bulk samples, the enamel slabs were sectioned using a low-speed diamond saw. The crystalline structures of samples were analyzed by XRD, and the obtained data were analyzed. The values of the lattice parameters were obtained using the equation of hexagonal crystalline structures. The... 

    Evaluation of crystalline changes and resistance to demineralization of the surface of human dental enamel treated with Er:YAG laser and fluoride using x-ray diffraction analysis and vickers microhardness

    , Article Laser Physics ; Volume 28, Issue 6 , 2018 ; 1054660X (ISSN) Behroozibakhsh, M ; Shahabi, S ; Ghavami lahiji, M ; Sadeghian, S ; Faal Nazari, N. S ; Sharif University of Technology
    Institute of Physics Publishing  2018
    This study aimed to investigate the changes in crystalline structure and resistance to demineralization of human dental surface enamel treated with erbium-doped yttrium aluminium garnet laser (Er:YAG) laser and fluoride. The enamel surfaces were divided into four groups according to the treatment process including, (L): irradiated with Er:YAG; (F): treated with acidulated phosphate fluoride gel (LF): Pre-irradiated surfaces with Er:YAG subjected to acidulated phosphate fluoride gel and (FL): laser irradiation was performed on the fluoridated enamel surface. Before and after the treatment procedure, the samples were evaluated using X-ray diffraction, scanning electron microscope (SEM) and the... 

    Numerical solution of non-fourier heat transfer during laser irradiation on tooth layers

    , Article Journal of Mechanical Science and Technology ; Volume 31, Issue 12 , 2017 , Pages 6085-6092 ; 1738494X (ISSN) Falahatkar, S ; Nouri Borujerdi, A ; Najafi, M ; Mohammadzadeh, A ; Sharif University of Technology
    This study reports on the simulation of temperature distribution of human tooth under a laser beam based on non-Fourier models. The temperature in the tooth depth that directly results from the conduction heat transfer process is caused by the lengthy thermal relaxation time in the tooth layers. A detailed tooth composed of enamel, dentin, and pulp with unstructured shape, uneven boundaries, and realistic thicknesses was considered. A finite difference scheme was separately adopted to solve time-dependent equations in solid layers and soft tissue of the tooth. In this study, a dual-phase-lag non-Fourier heat conduction model was applied to evaluate temperature distribution induced by laser... 

    Effect of RGO/Zn:XCd1- xS crystalline phase on solar photoactivation processes

    , Article RSC Advances ; Volume 6, Issue 52 , 2016 , Pages 46282-46290 ; 20462069 (ISSN) Moradlou, O ; Tedadi, N ; Banazadeh, A ; Naseri, N ; Sharif University of Technology
    Royal Society of Chemistry  2016
    A series of reduced graphene oxide/ZnxCd1-xS (RGO/ZnxCd1-xS) nanocomposites (0 < x < 1) with different ratios of Zn/Cd were synthesized via a facile hydrothermal route under optimized experimental conditions and were carefully characterized by various techniques. Because very little is known about the morphology, specific surface area, and crystal phase effects of RGO/ZnxCd1-xS crystals on their photoresponsivity, field-emission scanning electron microscopy (FE-SEM), BET surface area analysis and X-ray diffraction (XRD) data were studied to investigate their effects on photoactivity. Based on the results, a crystal phase transition from a cubic phase in RGO/Zn0.9Cd0.1S to a hexagonal... 

    Electrodeposition of well-defined gold nanowires with uniform ends for developing 3D nanoelectrode ensembles with enhanced sensitivity

    , Article Materials Chemistry and Physics ; Volume 213 , 2018 , Pages 67-75 ; 02540584 (ISSN) Bahari Mollamahale, Y ; Ghorbani, M ; Dolati, A ; Hosseini, D ; Sharif University of Technology
    Elsevier Ltd  2018
    Fabrication of well-defined gold nanowires (GNWs) is of significant importance in many fields such as sensing applications. In this study, the electrodeposition of well-defined GNWs inside polycarbonate (PC) template has been discussed in detail. GNWs were potentiostatically electrodeposited at different filling rates. The growth of GNWs at different stages of pore filling was monitored by electrochemical measurements and field-emission scanning electron microscopy (FE-SEM). It was confirmed that under growth rates between 2.5 and 4 nm/s, GNWs with smooth ends grew uniformly inside the template without any imperfections or corrugations. The length of GNWs was electrochemically controlled to... 

    Synthesis and characterization of pure metallic titanium nanoparticles by an electromagnetic levitation melting gas condensation method

    , Article RSC Advances ; Vol. 4, issue. 14 , 2014 , pp. 7104-7108 ; ISSN: 20462069 Mohammadi, A. V ; Halali, M ; Sharif University of Technology
    Pure titanium nanoparticles were synthesized by utilizing an Electromagnetic Levitation Melting Gas Condensation (ELM-GC) method. Pure bulk titanium samples were melted and evaporated by electromagnetic levitation technique in an inert gas atmosphere in a silica tube. Titanium nanoparticles were formed from ascending vapor by employing high purity argon and helium as carrier gases and cooling agents. Particle size and morphology of the produced nanoparticles were studied by Field-Emission Scanning Electron Microscopy (FE-SEM) and Dynamic Light Scattering (DLS) analysis. Results showed almost spherical nanoparticles with a narrow size distribution under both cooling atmospheres. The purity of... 

    Innovative semi-analytical methodology to predict automobile body temperature distribution in the curing ovens

    , Article Heat Transfer Engineering ; Volume 33, Issue 2 , Jun , 2012 , Pages 109-117 ; 01457632 (ISSN) Hanafizadeh, P ; Sajadi, B ; Saidi, M. H ; Sharif University of Technology
    In automobile painting industries, new automobile body products frequently should be tested in order to determine the actual thermal behavior of a paint curing process before starting mass production. During the hardening processes of dipped paint coating, applied in the electrophoretic enameling process, or top paint coating, applied in the final coating process, the automobile body must be warmed up according to the specific paint manufacturer curve. Consequently, prediction of car body temperature during the curing process may be vital in the design and performance analysis of the paint ovens. Numerical simulation of these processes may reduce expensive and time-consuming experimental... 

    The influence of surface nanocrystallization induced by shot peening on corrosion behavior of niti alloy

    , Article Journal of Materials Engineering and Performance ; Volume 24, Issue 8 , August , 2015 , Pages 3093-3099 ; 10599495 (ISSN) Olumi, S ; Sadrnezhaad, S. K ; Atai, M ; Sharif University of Technology
    Springer New York LLC  2015
    Nickel-titanium (NiTi) shape memory alloys have been widely used as implant materials, due to their superior shape memory properties and similar mechanical behavior to bone tissue. The presence of nickel on the surface of nickel-titanium alloy and release of this ion in the body environment will result in some allergic reactions. In current study, we used shot pinning process to produce nanocrystalline nickel-titanium alloy with increased corrosion resistance. Field emission scanning electron microscopy (FE-SEM), x-ray diffraction (XRD) analysis, and atomic force microscopy were employed to investigate the surface features of samples. The quantitative chemical analysis of NiTi and modified... 

    Modification of nanostructured anodized aluminum coatings by pulse current mode

    , Article Surface and Coatings Technology ; Volume 278 , 2015 , Pages 48-55 ; 02578972 (ISSN) Mohammadi, I ; Afshar, A ; Sharif University of Technology
    Elsevier  2015
    In this study, the effects of pulse current mode on corrosion resistance and mechanical properties of anodized coatings were explored. Thickness and hardness measurements, polarization and electrochemical impedance spectroscopy were employed to take mechanical and corrosion behaviors of the anodized coatings into consideration. Also, field-emission scanning electron microscopy (FE-SEM) was utilized to characterize the surface morphology of the coatings. It was shown that in short anodizing times, coating thickness is controlled by the heat concentrated on coating. Although at prolonged anodizing times, the coating thickness is affected by average current density. Hardness measurements showed... 

    Evaluation of the corrosion protection properties of an epoxy coating containing sol-gel surface modified nano-zirconia on mild steel

    , Article RSC Advances ; Volume 5, Issue 36 , Mar , 2015 , Pages 28769-28777 ; 20462069 (ISSN) Haddadi, S. A ; Mahdavian, M ; Karimi, E ; Sharif University of Technology
    Royal Society of Chemistry  2015
    In this study, the effect of surface modified nano-zirconia (nano-ZrO2) on the corrosion protection of epoxy coating on mild steel was investigated. An organosilane (trimethoxy methyl silane) was used as a surface modifier to improve the dispersability of the inorganic nanoparticles in the organic coating matrix. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) were used to characterize the sol-gel surface modified nanoparticles. The dispersability of the modified and unmodified nano-zirconia in an epoxy coating was examined by field emission-scanning electron microscopy (FE-SEM). Electrochemical impedance spectroscopy (EIS) and salt spray were employed to... 

    Effect of pulse current parameters on the mechanical and corrosion properties of anodized nanoporous aluminum coatings

    , Article Materials Chemistry and Physics ; Volume 183 , 2016 , Pages 490-498 ; 02540584 (ISSN) Mohammadi, I ; Ahmadi, Sh ; Afshar, A ; Sharif University of Technology
    Elsevier Ltd  2016
    In this study, the effects of pulse current parameters on corrosion resistance and mechanical properties of anodized coatings were evaluated. Hardness measurements, polarization and electrochemical impedance spectroscopy tests were employed to investigate the mechanical properties and corrosion behavior of these coatings. Also, field emission scanning electron microscopy (FE-SEM) was used to analyze the surface morphology and microstructure of the coatings. It was found that the properties of anodized coatings were dependent on various parameters, among which, time, temperature and pulse current parameters (current density limit, frequency and duty cycle) were optimized. Analysis of Variance... 

    Hydroxyapatite based and anodic titania nanotube biocomposite coatings: fabrication, characterization and electrochemical behavior

    , Article Surface and Coatings Technology ; Volume 287 , 2016 , Pages 67-75 ; 02578972 (ISSN) Ahmadi, S ; Mohammadi, I ; Sadrnezhaad, S. K ; Sharif University of Technology
    Elsevier  2016
    The main challenges of biological implants are suitable strength, adhesion, biocompatibility and corrosion resistance. This paper discusses fabrication, characterization and electrochemical investigation of anodized Ti6Al4V without and with a hydroxyapatite (HA) layer, HA/TiO2 nanoparticles (NPs) and HA/TiO2 nanotubes (HA/anodized). X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS) were used to characterize and compare properties of different samples. Dense HA with uniform distribution and 12.8 ± 2 MPa adhesive strength enhanced to 19.2 ± 4 MPa by the addition of TiO2 nanoparticles and enhanced to 23.1 ± 4 MPa by the... 

    Deposition of metallic molybdenum thin films on 304L steel substrate by SUT-PF

    , Article Surface and Coatings Technology ; 2016 ; 02578972 (ISSN) Hosseinzadeh, A ; Nazmabadi, M ; Vosoughi, N ; Sharif University of Technology
    Elsevier B. V 
    The present research work aims to employ plasma focus in order to deposit molybdenum (Mo) on the 304 stainless steel substrate. The processing parameters were shot numbers as well as the distance of substrate from the anode tip. Stereo, atom force microscopy (AFM) and field emission-scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray spectroscopy (EDS) were used to study the deposited coatings. Microhardness measurements were also performed on the coatings. Results indicated that the plasma focus can be successfully applied to deposit Mo anode on the stainless steel substrate. The coatings contained discrete pores with sizes varying by processing parameters. The... 

    Microstructural characterization and dry sliding wear behavior of spark plasma sintered Cu-YSZ composites

    , Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 26, Issue 7 , 2016 , Pages 1745-1754 ; 10036326 (ISSN) Mirazimi, J ; Abachi, P ; Purazrang, K ; Sharif University of Technology
    Nonferrous Metals Society of China  2016
    In the present study, yttria stabilized zirconia (YSZ) reinforced Cu matrix composite specimens were produced by spark plasma sintering (SPS). For comparison, pure Cu specimen was also produced in the same conditions. The effect of particles content on microstructure, relative density, electrical conductivity, and Vickers hardness was evaluated. The pin-on-disk test was also performed to determine dry sliding wear behavior of specimens under different wear conditions. After sliding wear tests, the worn surfaces were examined by field emission scanning electron microscopy (FE-SEM). Microstructural study showed satisfactory distribution of reinforcement particles in copper matrix. The relative... 

    Kinetic study and growth behavior of template-based electrodeposited platinum nanotubes controlled by overpotential

    , Article Materials Chemistry and Physics ; Volume 187 , 2017 , Pages 141-148 ; 02540584 (ISSN) Yousefi, E ; Dolati, A ; Imanieh, I ; Yashiro, H ; Kure-Chu, S. Z ; Sharif University of Technology
    Elsevier Ltd  2017
    Platinum nanotubes (PtNTs) are fabricated by potentiostatic electrodeposition at various overpotentials (−200 up to −400 mV versus SCE) in polycarbonate templates (PCTs) with pore diameter of 200 nm in a solution containing 5 mM H2PtCl6 and 0.1 M H2SO4. The synthesized PtNTs are characterized by field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The electrochemical growth mechanism within nanoscopic pores and the relationship between morphological variations and kinetic parameters are investigated for the first time. It is shown that more porous structure of nanotubes forms at high overpotentials possibly due to preferably nucleation. The... 

    Characterization of sol-gel derived silver/fluor-hydroxyapatite composite coatings on titanium substrate

    , Article Surface and Coatings Technology ; Volume 352 , 2018 , Pages 522-528 ; 02578972 (ISSN) Batebi, K ; Abbasi Khazaei, B ; Afshar, A ; Sharif University of Technology
    Elsevier B.V  2018
    A composite coating containing silver, fluoride and hydroxyapatite (Ag-FHA) was developed on titanium substrate by sol-gel method. Triethylphosphite, hydrated calcium nitrate, ammonium fluoride and silver nitrate were used respectively, as P, Ca, F and Ag precursors with a Ca:P ratio 1.67 and concentration of silver was 0.3 wt%. Coatings were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and atomic absorption spectrometry (AAS). Potentiodynamic polarization measurements in simulated body fluid proved corrosion protection caused by both Ag-FHA coatings. Antibacterial activity of coatings against... 

    Effect of oxidizing atmosphere on the surface of titanium dental implant material

    , Article Journal of Bionic Engineering ; Volume 16, Issue 6 , 2019 , Pages 1052-1060 ; 16726529 (ISSN) Khodaei, M ; Alizadeh, A ; Madaah Hosseini, H. R ; Sharif University of Technology
    Springer  2019
    Direct oxidation is a simple and effective method for titanium surface treatment. In this research, a titanium sample was directly oxidized at the high temperature in two different atmospheres, air and pure oxygen, to obtain better atmosphere for titanium surface treatment. The results of the Raman spectroscopy indicated that in both atmospheres, the rutile bioactive phase (TiO2) has been formed on the titanium surface. The results of X-ray diffraction (XRD) also revealed that the surface of oxygen-treated sample was composed of the rutile phase and titanium monoxide (TiO), while at the surface of the air-treated sample, the rutile phase and titanium dioxide had been formed. Further, the... 

    Self-healing epoxy nanocomposite coatings based on dual-encapsulation of nano-carbon hollow spheres with film-forming resin and curing agent

    , Article Composites Part B: Engineering ; Volume 175 , 2019 ; 13598368 (ISSN) Haddadi, S. A ; Ramazani S.A., A ; Mahdavian, M ; Taheri, P ; Mol, J. M. C ; Gonzalez Garcia, Y ; Sharif University of Technology
    Elsevier Ltd  2019
    The ability of an active protective organic coating to restore its protection functionality in case of a coating defect is of pivotal importance to ensure durable performance under demanding corrosive conditions. In this paper, a self-healing epoxy system is fabricated by separate encapsulation of epoxy and polyamine in carbon hollow spheres (CHSs) and the autonomous healing performance of the system applied on mild steel is investigated. CHSs were synthesized via a silica templating method using carbonization of polysaccharide shells formed on the surface of silica templates. Consequently, epoxy and polyamine were loaded in separate capsules by dispersion of CHSs into the dilute solutions... 

    Synthesis, characterization and catalytic activity of supported vanadium Schiff base complex as a magnetically recoverable nanocatalyst in epoxidation of alkenes and oxidation of sulfides

    , Article Journal of Organometallic Chemistry ; Volume 897 , 2019 , Pages 200-206 ; 0022328X (ISSN) Bagherzadeh, M ; Bahjati, M ; Mortazavi Manesh, A ; Sharif University of Technology
    Elsevier B.V  2019
    A new magnetically separable nanocatalyst was successfully synthesized by immobilizing of vanadyl acetylacetonate complex, [VO(acac)2], onto silica coated magnetite nanoparticles previously functionalized with 3-aminopropyltriethoxysilane (3-APTES) and reacted by 5-bromosalicylaldehyde to form Schiff base moiety. The obtained nanocatalyst was characterized by elemental analysis (CHN), FT-IR spectroscopy, Powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), inductively coupled plasma optical emission spectrometry (ICP-OES) and thermogravimetric analysis (TGA). Eventually, the resulting nanoparticles were used as catalyst for epoxidation of alkenes and... 

    Synergistic effect of Ni-based metal organic framework with graphene for enhanced electrochemical performance of supercapacitors

    , Article Journal of Materials Science: Materials in Electronics ; Volume 30, Issue 13 , 2019 , Pages 12351-12363 ; 09574522 (ISSN) Azadfalah, M ; Sedghi, A ; Hosseini, H ; Sharif University of Technology
    Springer New York LLC  2019
    Developing advanced electrode materials with metal–organic frameworks (MOFs) has increasingly attracted attentions as an effective method for improving supercapacitors performances. However, their poor conductivity has limited their use in energy applications. In this paper, an effective strategy is presented to reduce the electric resistance of MOFs by the in situ synthesis of Ni-based MOFs with graphene (Ni-MOF/graphene). The fabricated Ni-MOF/graphene composite was characterized by powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), Raman spectra, Brunauer–Emmett–Teller (BET) and...