Sharif Digital Repository

This study is aimed at optimizing the rice husk ash (RHA) content and bacterial concentration in self-compacting concrete (SCC). For this purpose, cement was partially replaced with RHA at 0%, 5%, 10%, 15%, 20%, 25%, and 30% by weight of cement. In addition, micro-silica (MS) was added to all mixes at a dosage of 10% by weight of cementitious materials. The mix with the optimum RHA content was supplied with bacterial cells with concentrations of 103, 105, and 107 cells/ml to reduce the formation of micro-cracks. The RHA concretes showed reduced workability with increasing RHA content. Energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) analyses were performed on... 

A new high-speed spinning disk reactor (HSSDR) was proposed and tested successfully. In this regard, barium sulfate (BaSO4) nanoparticles were synthesized using reactive crystallization processes. In this reactor, the rotational disk speed was varied from 5000 to 15 000 rpm. The effects of various design and operating parameters such as the rotational disk speed, feed entrance radius, volumetric flow rate of feed solutions, supersaturation, and free ion ratio were investigated in detail. The mean particle size (MPS) and specifications of the synthesized barium sulfate were investigated using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy and powder X-ray... 

In this work, uniform and monodisperse hollow carbon spheres (HCSs) are synthesized through two different processes using polydopamine (PDA), as a carbon precursor, and silica core as a template, under the modified Stöber condition. The surface morphology of the synthesized structures is characterized by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier-transform infrared spectroscopy (FT-IR). In the next step, the electrochemical behavior of isoprenaline (ISPN) is investigated by using glassy carbon electrode modified with a thin film of the synthesized hollow carbon spheres. The electrochemical characterization of the modified electrodes is... 

Hexagonal core–shell SiO2[–MOYI]Cl–]Ag nanoframeworks were synthesized via surface modification of hexagonal silica nanoparticles prepared from perlite (EP) as a cheap and abundant raw material. The prepared samples were well characterized by X-ray diffraction powder (XRD), energy dispersive X-ray (EDX), diffuse reflectance spectroscopy (DRS), Brunauer–Emmett–Teller (BET) specific surface area analysis, fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). The XRD patterns confirmed that Ag and AgCl crystalline phases were successfully loaded on the surface. The TEM images were also implied that the... 

This study investigated the influence of ultrafine fly ash (FA) on the mechanical properties, elevated temperature resistance and water stability of basalt fiber reinforced magnesium phosphate cement, and synergy mechanism was examined with the help of X-ray diffraction (XRD), thermogravimetric analysis (TGA), mercury intrusion porosimeter (MIP) and scanning electron microscopy energy dispersive spectroscopy (SEM/SEM-EDS) analysis techniques. Experimental results showed that incorporation of FA improved the mechanical properties, temperature resistance and water stability of MPC composites. TGA results exhibited that the mass loss of MPC composites was gradually reduced by increasing the... 

NiAl-TiC composites were synthesised by volume combustion (VC) method from elemental powders to improve the mechanical properties and high temperature performance of nickel aluminide. Synthesised specimens with porous nature were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis. XRD results showed that NiAl was dominant phase and other phases like Al 3 Ni 2 (in NiAl + 5 wt-% TiC, NiAl + 10 wt-% TiC specimens) and AlNi 3 (in equimolar NiAl-TiC) were present in specimens. Synthesised specimens of NiAl, NiAl + 5 wt-% TiC, NiAl + 10 wt-% TiC, NiAl + 15 wt-% TiC and equimolar NiAl-TiC achieved Vickers... 

SnS2-SnO2 nano-heterostructures are synthesized with two different precursors of thioacetamide (TAA) and thiourea (TU) at various solvent ratios (SR) of ethanol and water by using a facile, economical, scalable, and cost-effective solvothermal method. The obtained products have been characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), and Brunauer–Emmet–Teller (BET) techniques. It is found that different precursors and various SR values have an influence on the composition and morphologies of the prepared nanostructures, leading to variation in capacitive behavior of the fabricated electrodes.... 

In this present study, Tungsten Inert Gas (TIG) welding and powder filled cored wires with nitrogen shielding gas were utilized to produce TiC and TiN surface composite coatings on the titanium (Ti) sheet substrate. The TIG procedure was done at same welding parameters for all of prepared samples. Phase analysis and microstructures were done by X-ray Diffraction (XRD), Energy-Dispersive X-ray Spectroscopy (EDS), Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). The obtained results from XRD and EDS demonstrated that the presence of crystalline phases of TiC, TiN and Ti. SEM and OM exhibited formation of the spherical and dendritic TiC particles in a martensitic matrix and also,... 

In this present study, Tungsten Inert Gas (TIG) welding and powder filled cored wires with nitrogen shielding gas were utilized to produce TiC and TiN surface composite coatings on the titanium (Ti) sheet substrate. The TIG procedure was done at same welding parameters for all of prepared samples. Phase analysis and microstructures were done by X-ray Diffraction (XRD), Energy-Dispersive X-ray Spectroscopy (EDS), Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). The obtained results from XRD and EDS demonstrated that the presence of crystalline phases of TiC, TiN and Ti. SEM and OM exhibited formation of the spherical and dendritic TiC particles in a martensitic matrix and also,... 

Joining of dissimilar light metals by friction stir welding (FSW) is of interest to reduce weight and fuel consumption in the transport sector. Such coupled metals may need protective surface treatments, e.g. against wear or corrosion, for some applications. In this work, the formation of plasma electrolytic oxidation (PEO) coatings in a silicate-based electrolyte for corrosion protection of FSW AZ31B magnesium alloy-titanium joints has been studied. The joints, if unprotected, may be susceptible to severe galvanic corrosion in chloride-containing environments. The coatings were characterized by scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction. Mg2SiO4 and... 

In this work, sessile drop and low-bond axisymmetric drop shape analysis methods were coupled to provide some new aspects on stick-slip behavior as well as stick time of a drop on calcite surfaces. Slightly hydrophobic calcite surfaces typified with three irregular roughnesses were used to create irregular surfaces to mimic defects for the water-calcite-air systems. Polishing papers of 200, 600, and 1200 grit and a polishing machine were used to prepare surfaces. X-ray diffraction, energy dispersive X-ray spectroscopy, Fourier transform infrared, and atomic force microscopy techniques were employed to evaluate the chemical and physical properties of surfaces. A model was developed to predict... 

Hierarchical TiO2 nanoleafed nanorod thin film was successfully synthesized on the fluorine doped tin oxide glass substrate. For this purpose, the nanorods were coated on the TiO2 seeded substrate via the hydrothermal method. Then, nanoleafs were grown on the nanorods by aqueous chemistry. Field emission scanning electron microscopy, energy dispersive spectroscopy, and Raman spectroscopy were utilized for thin film characterization. The results clarified that anatase-phase nanoleafs were uniformly grown on the rutile-phase nanorods in the TiO2 coating. The photocatalytic performance of the thin film was determined by photodegradation of anionic and cationic organic pollutants, and the... 

In this study, evolution of intermetallic layer of the cold roll bonded bilayer of Aluminum-Steel sheets, during severe plastic deformation (SPD) followed by annealing has been investigated. The effect of such evolution on mechanical properties has been discussed. For this purpose, Constrained Groove Pressing (CGP) was used as a SPD process. Field emission scanning electron microscope equipped with energy dispersive spectroscopy and optical microscopy were used for examination of intermetallic compounds morphology and composition. Meanwhile, tensile properties of the bilayer sheets were evaluated. According to microstructural observations, continuous intermetallic layer was formed during... 

An efficient, green, novel and rapid vortex-assisted dispersive solid-phase extraction (VADSPE) technique was used for the preconcentration and determination of trace levels of Cu2+ followed by flame atomic absorption spectrometry. Graphene oxide (GO) was synthesized from graphite and then modified by pectic acid (poly-d-galacturonic acid, PA) to synthesize the pectic acid–graphene oxide (PA-GO) nanocomposite. The Fourier transform infrared spectrophotometry, field emission scanning electron microcopy, energy-dispersive X-ray spectroscopy and X-ray diffraction analysis were used to characterize the synthesized GO-PA nanocomposite. By using VADSPE technique, PA-GO was used as an adsorbent for... 

Aluminum-Al3Ti reinforced MMCs were produced with a large amount (up to ~30 vol%) of Al3Ti phase via mechanical alloying, hot extrusion and heat treatment (as a supplementary process) of the Al–Ti elemental powder mixture, respectively. Samples in each stage were studied precise and comprehensive by field emission electron microscope, energy dispersive spectroscopy, X-ray diffraction, differential scanning calorimetry, densitometry, macro and micssro hardness, nanoindentation and tensile tests. The results indicated that after 4-h vibratory milling, the aluminum crystallite size reached 63 nm and Al3Ti phase formed in powder mixture. After hot extrusion, the volume percentage of Al3Ti... 

In this work, the addition of a novel polyaniline (PANI)/silica (SiO2) nanostructure (PSn) in chitosan/polyvinyl alcohol nanofibers (CP) was evaluated to enhance the dye removal capacity of CP. Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS) results confirmed the chemical grafting of SiO2 on PANI nanoparticles. Brunauer-Emmett-Teller (BET) results showed a specific surface area of 61 m2 g−1 for the PSn filled CP nanofiber (CP-PSn). FE-SEM and EDS-elemental mapping results showed the uniform dispersibility of PSn in CP nanofibers. After the addition of PSn into CP, the adsorption capacity of... 

This study investigates the synthesis of CuCo2O4, BiVO4, and CuCo2O4/BiVO4 nanocomposite by the solvothermal method. The Physico-chemical properties of the samples were verified through Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Transmission Electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET). Evaluation of catalytic efficiency of the synthesized samples were done in promoting the 4-Nitrophenol reduction to 4-Aminophenol in the existence of high amount of sodium borohydride (NaBH4) as a reducing agent, and the progress of the catalytic reaction was monitored... 

Although important advances have been acquired in the field of electrocatalysis, the design and fabrication of highly efficient and stable non-noble earth-abundant metal catalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) remain a significant challenge. In this study, we have designed a superior bifunctional catalyst for OER and HER in alkaline media based on the Co-Mo-P/Zn-Co-S multicomponent heterostructure. The as-prepared multicomponent heterostructure was successfully obtained via a simple three-step hydrothermal-sulfidation-electrodeposition process consisting of star-like Co-Zn-S covered with Co-Mo-P. The structure and morphology evaluation of the... 

In the present study, an in-situ, two-step, highly controllable, fast, green, and facile strategy for fabricating the bimetallic cobalt-zinc-based metal-organic frameworks (MOFs) is employed for designing a non-enzymatic glucose sensing platform. The structural characterization, as well as the phase investigation of materials in each step, are assessed by X-ray diffraction, energy-dispersive X-ray spectroscopy, elemental mapping, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. Furthermore, the electrocatalytic activity of the CoZn-BTC/GC fabricated electrode toward the electro-oxidation of glucose is examined by various electrochemical techniques,... 

In the bone tissue engineering field (BTE), it is of significant importance to develop bioactive multifunctional scaffolds with enhanced osteoconductivity, osteoinductivity, and antibacterial properties required for lost bone tissue regeneration. In this work, a bioactive glass-ceramic scaffold was manufactured via a novel polymer-derived ceramics (PDC) manufacturing method. To gain antibacterial properties, the silver ions were incorporated in controlled amount along with other precursors in the PDC processing stage. Microstructural and structural properties of the fabricated silicate-phosphate glass-ceramic scaffold were evaluated by scanning electron microscopy (SEM) equipped with energy...