Sharif Digital Repository

A seeding-growth approach was used to prepare Au@Ag@Au core double shell nanoparticles which were loaded on a rutile-nanorods/anatase-nanobranches thin film via the impregnation method. The thin film was synthesized on a fluorine-doped SnO 2 substrate via three stages of (i)TiCl 4 treatment, (ii)hydrothermal, and (iii)aqueous chemistry. The photocatalytic capability of the newly developed nanostructure was higher than P25 TiO 2 thin film by 40% under visible light and by 100% under UV light irradiation. Photogenerated charges separation at the junctions of rutile-nanorods and anatase-nanobranches along with localized surface plasmon resonance followed by the hot electron transfer from the... 

The thin-film of hierarchical rutile/anatase TiO2 nanorod/nanoleafs on fluorine-doped tin oxide glass was prepared via a facile method. For this purpose, the hydrothermal method was used for the synthesis of rutile-phase nanorods on the TiO2 seeded FTO, and aqueous chemistry was applied for growing anatase-phase nanoleafs on the nanorods. The structural, morphological, and optical properties of coating characterized, and the thin-film utilized as the photoelectrode for dye-sensitized solar cell. The energy conversion efficiency of the newly developed nanostructure was higher than that of TiO2 nanorod thin-film by 40%. This increase could be ascribed to: (1) superior specific surface area... 

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... 

A facile, straightforward, and low-cost method is proposed to synthesize gold@silver@gold core double-shell nanoparticles. The technique is a seed-mediated growth protocol that contains four steps of (1) gold seed synthesis, (2) gold seed growth, (3) silver layer coating through silver salt reduction, and (4) gold layer deposition via gold precursor reduction. The prepared nanoparticles had a narrow size distribution and the average particle size of 28 ± 1 nm. Cysteine was introduced to the nanoparticles solution as a coupling agent to assemble nanoparticles. Aggregation-induced two-photon photoluminescence enhancement of three types assembled nanoparticles, i.e., gold@silver@gold,... 

Hierarchical TiO 2 nanorod/nanoflower thin film was synthesized on fluorine doped tin oxide glass via hydrothermal and aqueous chemistry methods. According to field emission scanning electron microscopy results, the thin film was crack-free and uniform. Primary nanorods had an average diameter of 95 nm and a length of 2 µm. They were perpendicular to the substrate owing to the TiO 2 prenucleation. Growth of the nanoflowers on the nanorods could increase both the specific surface area and roughness. X-ray diffraction and Raman spectroscopy showed that the nanorods were rutile; while the nanoflowers were anatase. Efficient electron transfer from anatase to rutile could therefore occur.... 

Estimation of muscle force is needed for monitoring or control purposes in many studies and applications that include direct human involvement such as control of prosthetic arms and human-robot interaction. A new model is introduced to estimate the force of muscle from the EMG signals. Estimation is based on Hammerstein-Wiener Model which consists of three blocks. These blocks are used to describe the nonlinearity of input and output and linear behavior of the model. The nonlinear network is designed base on the sigmoid network. The introduced model is trained by some data sets which are recorded from different people and tested by some other data sets. The simulation results show low error... 

Electrochemical activity of TiO2 nanotube arrays (NTAs) is restricted by a wide band gap of TiO2. To overcome this restriction, we considered systematic research on two effective methods of doping of TiO2 NTAs such as the N-doping and electrochemical reductive doping and predicting the proper application of them. Band gap narrowing was occurred from 3.16 eV for undoped TiO2 NTAs to 2.9 and 2.7 eV at N-doped and self-doped TiO2 ones respectively. The electrochemical responses of the TiO2 NTAs before and after doping were examined by cyclic Voltammetry (CV) curve. To understand the electrochemical behavior of the undoped and doped TiO2 NTAs, electrochemical impedance spectroscopy (EIS) was... 

Although morphological disorder of nanotube structure is further down than the nanoparticular electrode, its density of traps are the hindering effects in the charge transport. In this study, crack-free TiO2 nanotube membranes, which obtained through a re-anodizing process, are fixed on transparent fluorine–tin-oxide glass by applying a few drops of Titanium Isopropoxide without needing the TiO2 powder paste. Front-side illuminated dye sensitized solar cells fabricated by undoped, N-doped and blue TiO2 nanotube membranes are investigated. The electrical characteristics of TiO2 nanotube based dye sensitized solar cells are followed by theoretical analysis using simple one-diode model.... 

Chitosan/poly(vinyl alcohol)/amino-functionalized montmorillonite nanocomposite electrospun membranes with enhanced adsorption capacity and thermomechanical properties were fabricated and utilized for the removal of a model cationic dye (Basic Blue 41). Effects of nanofiller concentrations (up to 3.0 wt %) on the morphology and size of the nanofibers as well as the porosity and thermomechanical properties of the nanocomposite membranes are studied. It is shown that the incorporation of the nanoclay particles with ∼10 nm lateral sizes into the polymer increases the size of the pores by about 80%. To demonstrate the efficiency of the adsorbents, the dye removal rate is investigated as a... 

In feature-based image registration, feature selection and reduction methods play an important role in decreasing computational burden of these operations. In this paper, a new approach is introduced to reduce the dimension of extracted feature vectors of MR images. This approach is based on the selection of the maximum and minimum responses of the alpha stable filter for the MR images over the extracted features with different orientation in frequency domain. This algorithm selects the rotation invariant features which are suitable for image registration purposes. It has been shown that these features could efficiently describe the image elements. The discriminating ability of the features... 

Image matching plays an important role in many aspects of computer vision. Our proposed method is based on Scale Invariant Feature Transform (SIFT) which is one of the popular image matching methods. The main ideas behind our method are removing the excess keypoints, adding oriented patterns to descriptor, and decreasing the size of the descriptors. By doing these changes to SIFT, we would have oriented patterns of keypoints. In addition, the numbers of keypoints have been reduced and the places of keypoints would be selected more accurately, and also the size of the descriptors has been reduced  

The vibration of a simply-supported beam with rotary springs at either ends is studied. The governing equations of motion are investigated considering the nonlinear effect of stretching. These equations are made non-dimensional and solved to the first-order approximation using the two known methods, namely, the multiple scales and the mode summation. The first five natural frequencies of the beam for different pairs of the boundary condition parameters are evaluated. A multilayer feed-forward back-propagation artificial neural network is trained using these natural frequencies. The artificial neural network used in this study shows high degree of accuracy for the natural frequency of the... 

Spatially-varying intensity noise is a common source of distortion in medical images and is often associated with reduced accuracy in medical image registration. In this paper, we propose two multi-resolution image registration algorithms based on Empirical Mode Decomposition (EMD) that are robust against additive spatially-varying noise. EMD is a multi-resolution tool that decomposes a signal into several principle patterns and residual components. Our first proposed algorithm (LR-EMD) is based on the registration of EMD feature maps from both floating and reference images in various resolutions. In the second algorithm (AFR-EMD), we first extract a single average feature map based on EMD... 

The vibration of a simply supported beam with rotary springs at either ends is studied. The governing equations of motion are investigated considering the nonlinear effect of stretching. These equations are made non-dimensional and then solved to first order approximation using the two methods of the multiple scales and the mode summation. The first five natural frequencies of the beam for few pairs of the boundary condition parameters are evaluated. A multilayer feed-forward back-propagation artificial neural network is trained using these natural frequencies. The artificial neural network used in this study shows high degree of accuracy for the natural frequency of the beam with general... 

An investigation into the dynamics of vehicle-passenger-structure-induced vibration of suspension bridges traversed by accelerating vehicles is carried out. The vehicle including the driver and passengers is modeled as a half-car planer model with six degrees-of-freedom. In addition, the stiffness of compliant bushings at the connecting points of the shock absorbers to the body is considered. The bridge is assumed to obey the Timoshenko beam theory with axial load and arbitrary conventional boundary conditions. The roughness of the bridge is assumed as a differentiable function of location. Due to continuously moving the location of the variable loads on the bridge, and in the presence of... 

AIDS causes increasing mortality every year. With advancements in nanomedicine, different nanomaterials (NMs) have been applied to treat AIDS and overcome its limitations. Among different NMs, nanoparticles (NPs) can act as nanocarriers due to their enhanced solubility, sustained release, targeting abilities and facilitation of drug-dose reductions. This review discusses recent advancements in therapeutics for AIDS/HIV using various NMs, mainly focused on three classifications: polymeric, liposomal and inorganic NMs. Polymeric dendrimers, polyethylenimine-NPs, poly(lactic-co-glycolic acid)-NPs, chitosan and the use of liposomal-based delivery systems and inorganic NPs, including gold and... 

Purpose - This paper aims to develop an adaptive unscented Kalman filter (AUKF) formulation for orientation estimation of aircraft and UAV utilizing low-cost attitude and heading reference systems (AHRS). Design/methodology/approach - A recursive least-square algorithm with exponential age weighting in time is utilized for estimation of the unknown inputs. The proposed AUKF tunes its measurement covariance to yield optimal performance. Owing to nonlinear nature of the dynamic model as well as the measurement equations, an unscented Kalman filter (UKF) is chosen against the extended Kalman filter, due to its better performance characteristics. The unscented transformation of the UKF is shown... 

The influence of concrete strength on the ductility of RC flexural members is investigated. Tests were carried out on beams with three ranges of concrete strengths, and moment-curvature and deflection curves obtained. It is concluded that when the concrete is laterally confined by closed steel ties beams with various levels of concrete strength and very high tensile strength steel exhibit high ductility