Sharif Digital Repository

The interaction of intense femtosecond laser pulses with atomic Argon clusters has been investigated by using nanoplasma model. Based on the dynamic simulations, ionization process, heating, and expansion of a cluster after irradiation by femtosecond laser pulses at intensities up to 2 × 1017 Wcm-2 are studied. The analytical calculation provides ionization rate for different mechanisms and time evolution of the density of electrons for different pulse shapes. In this approach, the strong dependence of laser intensity, pulse duration, and laser shape on the electron energy, the electron density, and the cluster size is presented using the intense chirped laser pulses. Based on the presented... 

In the present study, the potential of doxorubicin hydrochloride (DOX)-loaded electrospun chitosan/cobalt ferrite/titanium oxide nanofibers was studied to investigate the simultaneous effect of hyperthermia and chemotherapy against melanoma cancer B16F10 cell lines. The cobalt ferrite nanoparticles were synthesized via microwave heating method. The titanium oxide nanoparticles were mixed with cobalt ferrite to control the temperature rise. The synthesized nanoparticles and nanofibers were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and vibrating sample magnetometer (VSM) analysis. The DOX loading efficiency and in vitro drug release of... 

High order harmonic generation is investigated for N2 and CO molecules under ten-cycle sin-squared laser pulse at 800 nm wavelength and I = 2 × 1014 W cm−2 intensity. In order to study effects of the asymptotic behavior of the exchange-correlation (XC) potentials, the time-dependent Kohn-Sham equations are numerically solved in the non-linear non-perturbative regime with four different XC potentials. Time-dependent electron localization function is used to get imaging on the temporal dependence of the electron density. Time-profile analysis was also utilized for studying long and short electron trajectories. It is found that the ionization energy values both molecules calculated by using... 

In the present work, an efficient method is theoretically investigated for extending high-order harmonics and ultrashort attosecond pulse generation in N2 and CO molecules by using the time-dependent density functional theory approach. Our results show that by utilizing chirped laser field in the presence of a low frequency field, not only is the harmonic cutoff extended remarkably but also the single short quantum trajectory is selected to contribute to the harmonic spectra. When a low frequency field is added to the two-color chirped laser field, the long quantum trajectories are suppressed and only the short quantum trajectories contribute to the higher harmonic emission mechanism. As a... 

We present a method for high-order harmonics generation of N2 and CO molecules under two-color circularly polarized counter-rotating laser pulses at frequencies of and 2. Pulse envelope in this investigation is sin-squared and the intensity of each laser beam is with ten-optical cycle (o.c.). We show that an isolated pulse with a pulse duration shorter than 20 attosecond from the superposition of several harmonics can be generated. Both two-color linearly- and bicircularly-polarized laser pulses are considered. Our results have also been compared with the outcomes of the previous theoretical works as well as experiment observations. It is found that for CO molecule, the... 

The generation of ultrashort attosecond pulse requires both an enhanced high harmonic generation and the spectral-phase control. In the present work, an efficient method is theoretically investigated for extending HHG cutoff energy in Br2 molecule using TDDFT. The effects of molecular orientation and carrier-envelope phase of the laser on the high harmonic spectrum are analyzed. As a result, by the fine modulations of the laser field, the harmonic plateau is enlarged and the position of structure-induced interference minimum shifts. We also provide a physical picture on the intensity dependence of the spectral minima in the harmonic spectra  

This article presents the results of 2D and 3D simulations of a bubble column reactor at steady state conditions and low gas flow rates. The simulations have been done based on a two-fluid model with a k - ε model used for turbulence modeling. The experimental data have been obtained by differential pressure transducer. For analyzing of hydrodynamic parameters such as hold up and velocity profiles of phases, a system consists of water tank and air aerated from bottom is set up. The simulations have been done based on two different approaches which are mixture and eulerian approaches. Despite the fact that these approaches lead to similar results, the convergence and stability of eulerian... 

An important aspect of production of gears by precision forging process is the prediction of load required to perform the process and to design the forging die. In this research a new kinematically admissible velocity field is presented to predict the forging load by an upper bound analysis. The analysis considers the shape of tooth profile, number of teeth, and frictional conditions between the die/punch and deforming material. To verify the predicted results the 7075 aluminum alloy billets were forged at temperature of 150 to 250 °C in a precision forging die designed to produce a spur gear of 5 teeth. A good agreement was found between the two sets of results at the filling stage of the... 

Considering the non-ideal behavior of fluids and their effects on hydrodynamic and mass transfer in multiphase. flow is very essential. Simulations were performed that take into account the effects of mass transfer and mixture non-ideality on the hydrodynamics reported by Bozorgmehry et al In this paper, by assuming the density of phases to be. constant and using Raoult's law instead of EOS and the fugacity coefficient definition, respectively, for both liquid and gas phases, the importance of nonideality effects on mass transfer and hydrodynamic behavior was studied. The results for a system of octane/propane (T = 323 K and P = 445 kPa) also indicated that the assumption of constant density... 

A new multifunctional filtration membrane was prepared by twofold advantages of conventional polymeric-membrane as the supporting layer and magneto-plasmonic Ag-doped ZnO@Fe3O4/MWCNTs nanocomposite as the functional layer. Poly acrylic acid (PAA)-modified polyamide (PA) discs (PAA-PA) were applied to increase the hydrophilicity of prepared membrane and X-Ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used for characterization. The grafting yield of PAA in the pores and on the surface of PA was 17 wt.% and weigh difference between PAA-PA membrane before and after modifying with the photocatalyst was 8.7 mg. The amount of photocatalyst loading in the prepared... 

Precision forging is a suitable process to produce spur gears due to its advantages such as reduction in machining time and production cost. The homogeneity in microstructure and mechanical properties of precision forging products can highly affect the performance of the gears during their service. In this research the effect of precision forging temperature on homogeneity of microstructure and hardness of forged gears of low carbon steel is studied. The microstructure and hardness map of the gears forged at a temperature range of 750-1150 °C revealed that the forging temperature of 950 °C is an optimum temperature to produce a spur five teeth gear with minimum inhomogeneity in the... 

Today, regarding the limitation and environmental side effects of fossil fuel resources, solar hydrogen production is one of the main interests in the energy research area. The development of visible light sensitized semiconductors based on non-toxic components, low cost and available bio-species is an ongoing approach for H2 generation based on water splitting reactions. Here, two different morphologies of TiO2 photoanodes, nanoparticulated and nanotubular, have been modified with simply extracted bacteriorhodopsin (bR) without any linker. Achieving a significant enhancement in photoconversion efficiency of TiO2 photoanodes, η% was increased from 2.9 to 16.5 by bR addition to the TiO2... 

The alarming energy and environmental crisis of our modern era necessitates scientists to propose alternatives to replace the scarce and harmful fossil fuels. The Sun, as a free, and abundant clean energy resource, presents a motivation for researchers to convert the sunlight to electrical power and store the H2 as an energy carrier by developing solar cells as well as water splitting devices, respectively. One of the fundamental parts of a solar energy convertor (solar cell/photoelectrochemical device), where the reduction reaction occurs, is the counter electrode (CE); the CE is commonly based on rare Pt. It is critical to substitute costly CEs with efficient, low-cost replacements, which... 

IL-1RI is the signaling receptor for the IL-1 family of cytokines that are involved in establishment of the innate and acquired immune systems. Glycosylated extracellular (EC) domain of the IL-1RI binds to agonist such as IL-1β or antagonist ligands and the accessory protein to form the functional signaling complex. Dynamics and ligand binding of the IL-1RI is influenced by presence of the glycosaminoglycans (GAGs) of the EC matrix. Here a combination of molecular dockings and molecular dynamics simulations of the unglycosylated, partially N-glycosylated and fully N-glycosylated IL-1RI EC domain in the apo, GAG-bound and IL-1β-bound states were carried out to explain the co-occurring... 

Interleukin 1 Receptor type I (IL-1RI) is a multi-domain transmembrane receptor that triggers the inflammatory response. Understanding its detailed mechanism of action is crucial for treating immune disorders. IL-1RI is activated upon formation of its functional assembly that occurs by binding of the IL-1 cytokine and the accessory protein (Il-1RAcP) to it. X-ray crystallography, small-Angle X-ray Scattering and molecular dynamics simulation studies showed that IL-1RI adopts two types of ‘compact’ and ‘extended’ conformational states in its dynamical pattern. Furthermore, glycosylation has shown to play a critical role in its activation process. Here, classical and accelerated atomistic... 

This article presents the research results on production and performance of palladium-only catalytic converters. Monolith is used as catalyst carrier and gamma alumina as substrate. Dipping method is used for monolith washcoating. Palladium as the active metal is impregnated on gamma alumina using wet impregnation to produce catalyst samples. The effects of factors such as percent solid in slurry, milling time, calcination time and temperature, pH and existence of Al(NO3)3 on wash-coat characteristics were studied experimentally. SEM, XRD, and BET tests were carried out on the samples. Catalyst performance was tested in an experimental reactor that was designed for this research. The results... 

Interleukin 1 Receptor type I (IL-1RI) is a multi-domain transmembrane receptor that triggers the inflammatory response. Understanding its detailed mechanism of action is crucial for treating immune disorders. IL-1RI is activated upon formation of its functional assembly that occurs by binding of the IL-1 cytokine and the accessory protein (Il-1RAcP) to it. X-ray crystallography, small-Angle X-ray Scattering and molecular dynamics simulation studies showed that IL-1RI adopts two types of ‘compact’ and ‘extended’ conformational states in its dynamical pattern. Furthermore, glycosylation has shown to play a critical role in its activation process. Here, classical and accelerated atomistic...