Sharif Digital Repository

Background: In nuclear medicine application often it is required to use computational methods for evaluation of organ absorbed dose. Monte Carlo simulation and phantoms have been used in many works before. The shape, size and volume in organs are varied, and this variation will produce error in dose calculation if no correction is applied. Materials and Methods: A computational framework for constructing individual phantom for dosimetry was performed on five liver CT scan data sets of Japanese normal individuals. The Zubal phantom was used as an original phantom to be adjusted by each individual data set. This registration was done by Spherical Harmonics (SH) and Thin-Plate Spline methods.... 

Novel organic-inorganic hybrid heterogeneous nanocatalysts were obtained by covalent anchoring of a molybdenum(vi) complex of salicylidene 2-picoloyl hydrazine, MoO2(sal-phz)(CH3OH), (1) on the surface of magnetic nanoparticles functionalized by one of two routes: in the first method, the surface of magnetic nanoparticles is directly modified with 3-chloropropyltrimethoxysilane yielding 1A. In the second method, magnetic nanoparticles were silica-coated with tetraethoxysilane and then with 3-chloropropyltrimethoxysilane yielding the intermediate 2B. Then complex 1 was grafted on the surface of 1A or 2B through covalent interaction yielding 2A or 3B, respectively. The nanocatalysts 2A and 3B... 

Nano-manipulation is one of the most important aspects of nano-robotics and nano-assembly. The positioning process is considered by many researches to be one of the most important parts of nano-assembly, but has been poorly investigated, particularly for biologic samples. This Letter is devoted to modelling the process of positioning a biomolecule with atomic force microscopy (AFM) in an aqueous media using molecular dynamics simulations. Carbon nanotube (CNT) and graphite sheet are selected as AFM tip and substrate, respectively. To consider the effects of the medium on the manipulation, several models for decreasing the calculations including implicit, coarse grained, and all-atom methods... 

Normal human breathing exhibits complex variability in both respiratory rhythm and volume. Analyzing such nonlinear fluctuations may provide clinically relevant information in patients with complex illnesses such as asthma. We compared the cycle-by-cycle fluctuations of inter-breath interval (IBI) and lung volume (LV) among healthy volunteers and patients with various types of asthma. Continuous respiratory datasets were collected from forty agematched men including 10 healthy volunteers, 10 patients with controlled atopic asthma, 10 patients with uncontrolled atopic asthma, and 10 patients with uncontrolled non-atopic asthma during 60 min spontaneous breathing. Complexity of breathing... 

Electrospinning of biopolymers has gained significant interest for the fabrication of fibrous mats for potential applications in tissue engineering, particularly for wound dressing and skin regeneration. In this study, for the first time, we report successful electrospinning of chitosan-based biopolymers containing bacterial cellulous (33 wt %) and medical grade nanodiamonds (MND) (3 nm; up to 3 wt %). Morphological studies by scanning electron microscopy showed that long and uniform fibers with controllable diameters from 80 to 170 nm were prepared. Introducing diamond nanoparticles facilitated the electrospinning process with a decrease in the size of fibers. Fourier transform infrared... 

This paper scrutinizes the magnetic field effect to deliver the superparamagnetic nanoparticles (SPMNs) through the Blood Brain Barrier (BBB). Herein we study the interaction between the nanoparticle (NP) and BBB membrane using Molecular Dynamic (MD) techniques. The MD model is used to enhance our understanding of the dynamic behavior of SPMNs crossing the endothelial cells in the presence of a gradient magnetic field. Actuation of NPs under weak magnetic field offers the great advantage of a non-invasive drug delivery without the risk of causing injury to the brain. Furthermore, a weak magnetic portable stimulator can be developed using low complexity prototyping techniques. Based on MD... 

One crucial part of an image registration algorithm is utilization of an appropriate similarity metric. For common similarity metrics such as CC or MI, it is assumed that the intensities of image pixels are independent from each other and stationary. Accepting these assumptions, one will have difficulty doing image registration in the presence of spatially varying intensity distortion. In Myronenko et al. [5] a solution based on minimization of residual complexity is introduced to solve this problem. In this work, the weakness of RC method is investigated for more complex spatially varying intensity distortions and a modification of this method is presented to improve its performance in such... 

An efficient synthesis of pentacyclic indole derivatives is achieved via domino Knoevenagel-hetero-Diels-Alder reactions of indolin-2-thiones and O-propargylated salicylaldehyde derivatives in CH3CN in the presence of 10 mol % of ZnO as a heterogeneous catalyst. The products are formed in good to excellent yields  

Abdominal recordings of fetal ECG (fECG) have lower signal-to-noise ratio (SNR) as compared with invasive procedures. In this paper we have combined two previously proposed methods, one for extracting fECG, called piCA and the other, a transformation based on Hilbert transform to enhance the R-peaks. The combination of these methods seems to work well in situations of noisy data and fetal repositioning. Also a comparison is done by using ICA in order to extract the fetal signals. Performance of both methods is studied separately. Results show that applying the transformation on the components extracted with the use of piCA (after maternal ECG cancellation), had a very good performance. Also,... 

A robotic system with 6 DOF mobility was proposed for reduction of femoral shaft fractures based on Stewart platform. A plan for implementing the platform on bone fragments was introduced and a step by step strategy for performing the reduction procedure, based on the system's inverse kinematic solution, was proposed. The efficacy of the system was evaluated in some case studies and it was shown that it can be locked to act as an external fixator  

Neural activity is very important source for data mining and can be used as a control signal for brain-computer interfaces (BCIs). Particularly, Magnetic signals of neurons are enriched with information about the movement of different part of the body such as wrist movement. In this paper, we use MEG (Magneto encephalography) signals of two subjects recorded during wrist movement task in four directions. Data were prepared for BCI competition 2008 for multiclass classification. Our approach for this classification problem consists of PCA as a noise reduction method, ULDA for feature reduction and various linear classifiers such as Bayesian, KNN and SVM. Final results (58%-62% for subject 1... 

Background: The early repolarization pattern (ERP) has been considered a normal variant in electrocardiography (ECG) for a long time. Nevertheless, increasing evidence has demonstrated its association with adverse outcomes. Objectives: The present study aimed to evaluate the prevalence of ERP in the Iranian general population and demonstrate its clinical and ECG correlates. Methods: A cross sectional study, comprising 1424 consecutive healthy adult individuals, was conducted at two university based hospitals in Tehran, Iran in 2012-2013. The ERP prevalence, clinical characteristics and ECG morphology were investigated in volunteers. Results: ERP was present in 136 out of 1,424 people (9.6%).... 

In this study, AgxNi100-x, and CoxNi100-x (x = 0, 20, 40, 60, 80, and 100) bimetallic nanoparticles were successfully decorated on the surface of CeO2 nanorods derived from Ce-metal organic frameworks (Ce-MOF). The as-synthesized products were characterized using different techniques including XRD, FE-SEM, EDX, TEM, ICP, and BET. The as-prepared nanocomposites showed remarkable catalytic activity towards the reduction of organic pollutants such as 4-nitrophenol (4-NP), and rhodamine-B dye (RhB) by NaBH4 solution, with high stability and reusability for five consecutive cycles. The obtained results indicated that among these nanocomposites, Ag80Ni20@CeO2, and Co60Ni40@CeO2 exhibited the best... 

In this study, MoS2/reduced graphene oxide (rGO) was used as a cocatalyst to synthesize very highly efficient Cu2O/MoS2/rGO for cooperative catalytic applications. The resulting nanocomposite was characterized by various analytical techniques and applied for catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol and photocatalytic degradation of Acid blue 92. Cu2O/MoS2/rGO composite presents superior performance to pure Cu2O particles in both catalytic and photocatalytic reactions. This excellent activity demonstrates synergistic effect of MoS2/rGO as a cocatalyst in the nanocomposite. The role of the active sites in the reduction of 4-NP and degradation of dye was discussed and... 

Herein, we report the impact of chromium doping on the physical properties, electronic band structure and photovoltaic characteristics of their corresponding devices based on dye-sensitized solar cells (DSCs). Different DSCs with various compositions of the photoanode electrodes are fabricated to study their optical, structural, conduction band edge, donor density, depth of trap states and photoelectrochemical properties using X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), field-emission scanning electron microscopy (FE-SEM), Mott-Schottky capacitance analysis, chemical capacitance and electrochemical impedance spectroscopy (EIS) measurements. For such studies, the Cr-doped... 

The main aim of this research is to improve the photocatalytic activity of TiO2 nanotubes by co-doping with copper and sodium for application in the water splitting process as a photoanode. The doping was performed simultaneously to the anodizing process through a single-step treatment. The synthesized TiO2 nanotube array (TNA) was characterized by applying FESEM (Field Emission Scanning Electron Microscopy), XRD (X-ray Diffraction), DRS (Diffraction Reflection Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy) analyses. The results of XPS analysis proved the presence of copper with valence (2+) and carbon and sodium with valence (1+). Moreover, DRS tests showed a reduction in the band... 

Perovskite solar cells with an inverted p-i-n architecture were constructed under ambient conditions by employing materials of lower cost than standard cells. Thus, graphene oxide was used as a hole transporting material and Li-modified graphene oxide as an electron transporting material, while Al was used as a counter electrode. A maximum solar conversion efficiency of 10.2% was achieved by adding a Ti-based sol on the top of the Li-modified graphene oxide layer. © The Royal Society of Chemistry  

Kinetic modeling of CO hydrogenation over Fe-Co-Mn catalyst was investigated; a ternary catalyst was prepared using incipient wetness impregnation. The kinetic parameters were determined from experiments carried out in a fixed bed micro-reactor under the following process conditions: T = 523.15-533.15 K, P = 1-10 bar, H2/CO = 1/1-3/1 and space velocity = 4500 h-1. Seventeen rate expressions were derived from five different mechanisms according to Langmuir-Hinshelwood-Hougen-Watson (LHHW) and Eley-Rideal (ER) mechanisms and were tested against the experimental data. Non-linear regression method was used to estimate different kinetic parameters; according to the obtained experimental results... 

Background and purpose: To protect against any potential adverse effects to human health from localised exposure to radio frequency (100 kHz–3 GHz) electromagnetic fields (RF EMF), international health organisations have defined basic restrictions on specific absorption rate (SAR) in tissues. These exposure restrictions incorporate safety factors which are generally conservative so that exposures that exceed the basic restrictions are not necessarily harmful. The magnitude of safety margin for various exposure scenarios is unknown. This shortcoming becomes more critical for medical applications where the safety guidelines are required to be relaxed. The purpose of this study was to quantify... 

Background: Chronic low back pain (CLBP) disability has been particularly frustrating because its treatment has been a great therapeutic challenge. Disability has been suggested to depend on different factors that should be found and considered in the medical management. The inter-segmental coordination is often impaired in CLBP subjects; however, to the best of our knowledge, there is no evidence about the relationship between the existence of coordination problems and disability in CLBP patients. Objective: To evaluate the correlation between sagittal plane trunk-pelvis intersegmental coordination parameters during walking and disability level in CLBP patients. Methods: Kinematic data were...