Sharif Digital Repository

Atherosclerosis as a common cardiovascular disease is a result of both adverse hemodynamics conditions and monocyte deposition within coronary arteries. It is known that the adhesion of monocytes on the arterial wall and their interaction with the vascular surface are one of the main parameters in the initiation and progression of atherosclerosis. In this work, hemodynamic parameters and monocyte deposition have been investigated in a 3D computational model of the Left Anterior Descending coronary artery (LAD) and its first diagonal branch (D1) under the heart motion. A one-way Lagrangian approach is performed to trace the monocyte particles under different blood flow regimes and heart motion... 

In terms of manufacturability, there is a high tendency to deposit light-absorbing CuInS2 films by solution processing methods like ink-based depositions. In particular, for nanoparticle inks, the synthesis of highly dispersed and stable inks, with uniformity in the deposition process, is a serious challenge. Here, we demonstrate a novel two-step low-temperature CuInS2 film deposition method in which the In2S3 is deposited first. It then partially is converted into CuInS2 through the infiltration of Cu+ ions in the In2S3 layer in a dip-coating process. The resulting films are highly uniform, with diffraction peaks indicating the formation of pure CuInS2 phase. The proper stoichiometry of... 

Hematite (α-Fe2O3) is a promising candidate for water oxidation applications due to its abundance in the earth crust and its suitable bandgap. However, hematite performance is severely limited by electron-hole recombination at its interface with the electrolyte; something that can be addressed using electrocatalysts. In this report, we evaluate the influence of a ternary NiFeCo co-catalyst to enhance the water oxidation performance of hematite photoanodes. Thus, NiFeCo co-catalyst is optimized for hematite thin films with i) dense and ii) porous (nano-rod) morphologies. Both hematite films are prepared using electron beam evaporation method followed by an annealing step and NiFeCo... 

Biocompatible nanostructured coating plays an important role in enhancement of osseointegration ability of metallic implants. This study sets out to obtain optimized SiC concentration in Hydroxyapatite (HA) coating on AISI 316L stainless steel alloy through electrophoretic deposition method. Effect of SiC concentrations (1, 2, and 3%.wt) on the morphology, corrosion behaviour, and mechanical properties of the HA coating is investigated. Results show that SiC could obstruct the formation and growth of micro cracks in the HA coating where HA-3%SiC is considered as a crack free coating. Electrochemical tests reveal that SiC has improved the corrosion resistance of HA coating, and HA-3%SiC... 

Here, cobalt oxide nanostructures synthesized on vertically aligned copper oxide nanowires (NWs) have been investigated as a possible anode material for Lithium-ion batteries (LIBs). Copper oxide NWs were formed by thermal oxidation of electrochemically deposited copper on the stainless steel mesh substrate. The process used allows the formation of highly dense copper oxide NWs with excellent adhesion to the conductive current collector substrate. A simple hydrothermal method was implemented for the deposition of cobalt oxide nanostructures on the copper oxide NWs. The as-prepared binder-free copper oxide@cobalt oxide NWs electrode exhibits a high initial specific capacity of 460 mAh g-1 at... 

A cost-effective, durable, and easy-to-produce improvement in bifunctional electrocatalysts for water splitting is crucial for future renewable energy systems. In this present study, shape-controlled one-dimensional (1D) phosphorized cobalt (CoP) on 3D porous nickel foam (NiF) was synthesized through successive treatment of commercial NiF with acetone and ethanol, followed by hydrothermal growth of Co and final process of phosphorization by thermochemical reactions. The evaluations of products proved reduced overpotential (270 mV at 10 mA. cm−2 for hydrogen evolution reaction (HER) process and a low overpotential of 320 mV to reach a high current density of 20 mA. cm−2), low Tafel slope... 

In this work, synthesis of CuIn0.75Ga0.25S2 (CIGS) nanoparticles, the formation of stable dispersion, deposition of high-quality films and, fabrication of thin-film Perovskite solar cells are reported. The stability of nanoparticle ink is crucial in the formation of device-quality films. The chalcogenide-based materials are widely used in thin-film solar cells; in particular, Cu(In,Ga)S2 are used as an absorber and hole transporting layer. In the present study, the nanoparticles of about 20 nm size and bandgap of 1.5 eV are synthesized using a heat-up method. A variety of solvents are used as dispersing media and the stability of the inks is evaluated by precise optical monitoring. We... 

SnO2 is considered as one of the high specific capacity anode materials for Lithium-ion batteries. However, the low electrical conductivity of SnO2 limits its applications. This manuscript reports a simple and efficient approach for the synthesis of Sb-doped SnO2 nanowires (NWs) core and carbon shell structure which effectively enhances the electrical conductivity and electrochemical performance of SnO2 nanostructures. Sb doping was performed during the vapor-liquid-solid synthesis of SnO2 NWs in a horizontal furnace. Subsequently, carbon nanolayer was coated on the NWs using the DC Plasma Enhanced Chemical Vapor Deposition approach. The carbon-coated shell improves the Solid-Electrolyte... 

Condensation heat transfer on stainless steel tube utilizing superhydrophobic coatings was investigated. The electrophoretic deposition and spraying methods were employed to coat the tubes’ outer surface. The mixture that was synthesized for spray coating was a hybrid paint. It incorporated polyurethane matrix and a colloidal suspension containing organic nanoparticles. The hybrid paint had a proper adhesion to the substrate which caused more durability compared to the electrophoretic coating. The agglomeration of nanoparticles in the hybrid paint caused the formation of particles with larger size compared to the particles in the electrophoretic coating. Consequently, contact angle... 

In the metal deposition process, the performance of the nozzle is crucial to the quality of clad. Continuous coaxial nozzles are broadly used in this process for repairing two- and three-dimensional parts, because it can create a homogeneous distribution of powder particles. In addition, an inert gas can be applied using this type of nozzles which shields powder particles and laser interaction zone, and prevents the surface from oxidizing at high process temperatures. However, when this type of nozzle is tilted from the vertical axis for cladding non-horizontal surfaces, the effect of gravity on powder particles affects the uniformity of powder distribution at the nozzle outlet. This matter... 

We report on the response of a monolithic high Tc transition-edge bolometer to about 3 mmWave for the first time. The detector structure consisting of 400-nm YBa2Cu3O7-x(YBCO) film on buffered yttria stabilized zirconia substrate without any coupled antenna, shows bolometric type responsivity to the 3-mmWave radiation at its transition temperature. The YBCO thin film Ce0.9La0.1O2 buffer layer are both fabricated by the metal-organic deposition method. The meander line pattern of the bolometer is designed for obtaining maximum absorption and responsivity possible when the polarized radiation of the source is aligned with the pattern. Meander lines are 50 micrometers wide and 1.5-mm long. We... 

Multi-component nanocomposite thin films (composed of cellulose nanofiber (CNF), alginate, bioglass nanoparticles (BG NPs) and gentamicin) were prepared by using cathodic electrophoretic deposition (EPD) under different isostatic pressures of 10−2 mbar (LP), atmospheric (AP), and 5 bar (HP). According to thermal gravity analysis, larger amounts of CNF and alginate could be deposited on the surface at the AP condition in comparison with the LP and HP conditions. On the other hand, higher amounts of the BG NPs could be deposited at the LP condition as compared to the other conditions. The drug (gentamicin) loading/releasing of the samples prepared at the HP condition was found to be higher... 

Chemical processing of two-dimensional (2D) transition metal dichalcogenides has attracted immense attention due to their unique optical, electrical, and catalytic properties. In this paper, we show that under special conditions during seedless chemical vapor deposition (CVD), it is possible to grow large-area 2D WS2 layers with disc-shaped morphology, which has been scarcely reported. Detailed characterizations of the CVD-grown layers by Raman spectroscopy, atomic force microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy have revealed that a gradient in the precursor concentration in the gas phase and strain energy in the deposited hexagonal clusters favor... 

Thin films of bismuth and iron oxides were obtained by atomic layer deposition (ALD) on the surface of a flexible substrate poly(4,4′-oxydiphenylene-pyromellitimide) (Kapton) at a temperature of 250°C. The layer thickness was 50 nm. The samples were examined by secondary-ion mass spectrometry, and uniform distribution of elements in the film layer was observed. Surface morphology, electrical polarization, and mechanical properties were investigated by atomic force microscope, piezoelectric force microscopy, and force modulation microscopy. The values of current in the near-surface layer varied in the range of ±80 pA when a potential of 5 V was applied. Chemical analysis was performed by... 

In the last decade, the power conversion efficiency (PCE) of solution-processed perovskite solar cells (PSCs) in the lab-scale has reached an incredible level of 25.5%. Generally, PSCs are composed of a stack consisting of a perovskite thin-film sandwiched between an electron transporting layer (ETL) and a hole transporting layer (HTL). Although the quality of the ETL and HTL interfaces with the perovskite thin-film is important, the quality of the perovskite thin-film is also critical to achieving high-performance PSCs. Low-temperature deposition of organic-inorganic perovskite thin-films by simple solution processes is one of the significant advantages of PSCs compared to other... 

Deposition of asphaltenes upon precipitation is a main flow assurance concern, which propelled the development of various experimental and modeling techniques to accurately predict its occurrence. This work develops an integrated approach combining thermodynamic and deposition modules with a multiphase flow simulator to simultaneously model asphaltenes precipitation and deposition in wellbores. The Peng-Robinson equation of state and the modified Miller-Flory-Huggins theory are used to calculate the thermodynamic properties of the oil and asphaltenes precipitation, respectively. The deposition module is based on conservation laws for asphaltenes transport and is linked to the flow simulator... 

Developing high-performance supercapacitors is of great significance in the area of renewable energies by virtue of having both high energy and power densities. In this work, an innovative strategy is employed for the fabrication of binder-free binary nickel–cobalt-sulfide (NCS) nanosheets (NSs) directly decorated onto the hydrothermal nickel-sulfide (Ni3S2) nanowires (NWs) as the positive electrodes. The NCS/Ni3S2-nickel foam (NF) positive electrodes rendered superior specific capacity of 499.1 mAh.g−1 at 6 A.g−1. Encapsulated iron into the carbon sphere hosts (Fe-HTCSs) are used as the negative counterparts, exhibiting remarkable specific capacitance of 336.6 F.g−1 (at 0.1 A.g−1). The... 

Evolution of renewable energies in the era of the modernized world has been strongly tied up to the incessant development of high-performance energy storage systems benefiting from both high energy and power densities. In the present work, binder-free positive electrodes are fabricated via a facile electrochemical deposition route in which copper oxide nanorods (CuO NRs) directly grown onto the copper foam (CF) are decorated with bimetallic cobalt-zinc sulfide nanoarrays (Co-Zn-S NAs). The fabricated Co-Zn-S@CuO-CFs represent promising specific capacity of 317.03 C.g−1 at 1.76 A.g−1, along with superior cyclic stability (113% retention after 4500 cycles). Negative electrodes were further... 

Active edge sites of MoS2 nanosheets exhibit promising futures for hydrogen evolution reaction (HER), comparable with remarkable performances of highly cost platinum. However, 3D structures of MoS2 suffer from a lack of high mobility and unexposed active sites which lower the electrocatalytic activity. In this study, we show that there is a balance between increasing the active sites on the one hand and managing the charge transfer to facilitate the reaction on the other hand, and achieving this balance increases the efficiency of the electrocatalyst tremendously. For this purpose, we directly attached exfoliated MoS2 nanosheets onto carbon cloth (CC) substrate as a 3D network of conductive... 

In this study, ZrO2 coatings with different thicknesses were grown by the electron beam evaporation technique. The crystalline structure was studied by XRD analysis which suggested the tetragonal and monoclinic phases for ZrO2 coatings. Additionally, the film thickness slightly enhanced the crystallinity. The surface morphology and fractal features were analyzed using Scanning Electron Microscopy (SEM). The surface statistical parameters and the fractal geometry were employed to analyze the impact of the coating thickness and homogeneity on the morphology of the films. The statistical processing and fractal dimension revealed variations in the morphology parameters due to the electron beam...