Sharif Digital Repository

Abstract : Vertically aligned carbon nanotube (CNT) arrays were synthesized by thermal chemical vapor deposition (CVD) on stainless steel substrates coated by cobalt nanoparticles as catalyst. Morphological and elemental analyses conducted by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) revealed that bamboo-like CNTs were blocked by Co nanoparticles at the tips. The fabricated nanotubes underwent functionalization by electrochemical oxidation in sulfuric acid, and the subsequent structural studies, as well as Fourier transform infrared (FTIR) spectroscopy confirmed that the tips of functionalized CNTs were opened while oxygenated functional groups were... 

Acute T cell-mediated rejection (TCMR)is a major complication after renal transplantation. TCMR diagnosis is very challenging and currently depends on invasive renal biopsy and nonspecific markers such as serum creatinine. A noninvasive metabolomics panel could allow early diagnosis and improved accuracy and specificity. We report, in this study, on urine metabolome changes in renal transplant recipients diagnosed with TCMR, with a view to future metabolomics-based diagnostics in transplant medicine. We performed urine metabolomic analyses in three study groups: (1) 7 kidney transplant recipients with acute TCMR, (2) 15 kidney transplant recipients without rejection but with impaired kidney... 

This paper investigates the applicability of frequency-domain system identification technique to achieve the equivalent linear dynamics of an autonomous underwater vehicle for control design purposes. Frequency response analysis is performed on the nonlinear and coupled dynamics of the vehicle, utilizing the CIFER® software to extract a reduced-order model in the form of equivalent transfer functions. Advanced features such as chirp-z transform, composite window optimization, and conditioning are employed to achieve high quality and accurate frequency responses. A particular frequency-sweep input is implemented to the nonlinear simulation model to achieve pole-zero transfer functions for yaw... 

So far, many methods have been proposed to classify items based on ABC analysis, but the results of these methods have had relatively low compliance with the principles of ABC. More precisely, collective value and sometimes the number of items belonging to each category in the methods provided do not meet the basic requirements of ABC called Pareto’s principle. In this study, a number of hybrid methodologies including Shannon’s entropy, TOPSIS (the technique for order preference by similarity to ideal solution) and goal programming are respectively used for determining the weight of criteria which are effective in the inventory items classification, calculations of each item value and its... 

An important challenge in smart environments is how to manipulate the smart objects. Although mobile applications are typically used for controlling a smart environment, no previous study has evaluated the users performance in manipulating smart objects under different environmental complexities. This article presents an experimental comparison between three different selection techniques 3-D, 2-D, and physical user interfaces (UIs). We evaluate these techniques across two levels of environment complexity measuring 51 participants timing data and errors. Our results indicate that the 3-D UI is superior for task completion time and error, and the 2-D UI is not a better solution than the... 

Background: Females are two times more likely to develop patellofemoral pain (PFP) than males. Abnormal trunk and pelvis kinematics are thought to contribute to the pathomechanics of this condition. However, there is a scarcity of evidence investigating proximal segments kinematics in females with PFP. Research question: The purpose of this study was to investigate whether females with PFP demonstrate altered trunk, pelvis, and knee joint kinematics compared with healthy controls during running. Methods: Thirty-four females (17 PFP, 17 controls) underwent a 3-dimensional motion analysis during treadmill running at preferred and fixed speeds, each trial for 30 s. Variables of interest... 

In this study, titanium substrates which previously oxidized through Micro arc oxidation method, was coated by Hydroxyapatite (HAp) coating once more by means of the same method. Morphology, topography and chemical properties as well as phase composition and thickness of layers were studied to reveal the effect of the electrolyte concentration on coating features. According to results, the obtained coatings are consisted of HAp and titania as the major phases along with minor amounts of calcium titanate and α-tri calcium phosphate. Ca and P are present on surface of obtained layers as well as predictable Ti and O based on the XPS results. Thickness profile of coatings figured out that by... 

Micro Arc Oxidation (MAO) process was utilized to fabricate nano bioceramic TiO 2-hydroxyapatite coatings on titanium substrates. Samples were produced in electrolytes contained 1 g/l β-glycerophosphate and 5, 10 and 15 g/l calcium acetate for 3, 6 and 10 min at 350 V. The techniques including XRD, XPS, SEM, FESEM and EDX were employed to study the effect of processing parameters. Hydroxyapatite, anatase, α-tri calcium phosphate and calcium titanate phases as well as 30-60 nm-size crystals were detected in the coating layer. It was also observed that the pore volume would increase by increasing the electrolyte concentration. The growth time was also found to influence the total pore volume.... 

In the current study, gold nanoparticles (AuNPs) were prepared using the green synthesis method using Artemisia annua extract, loaded into niosomes, and investigated their cytotoxicity and apoptotic effects. To optimize the niosomal formulation containing AuNPs, the effects of surfactants: cholesterol molar ratio, Span 60: Tween 60 M ratio, and AuNP concentration (µg/mL) were investigated. After examining the drug release profile, mathematical models were assessed to predict release kinetic. The cytotoxicity of noisome encapsulated AuNPs and free AuNPs was evaluated against human ovarian cancer cell line (A2780) by MTT assay. The apoptotic/necrosis ratio was studied using flow cytometry as... 

In this paper, hydrogen management in refineries is examined considering a new perspective to optimize refinery costs. In order to minimize the total annual cost in refineries a mixed-integer non-linear programming (MINLP) model has been developed. Retrofitting the hydrogen network and determining the hydrogen surplus capacity of refineries are the main outputs of the proposed model. Then, to utilize this surplus capacity and increase the profitability of refineries, surplus hydrogen is used to produce electricity and ammonia. The results of a case study showed that retrofitting of the hydrogen network can save 12% in the consumption of fresh hydrogen from hydrogen plants. After retrofitting... 

Orthogonal frequency division multiplexing (OFDM) is used in many wireless communication. The important drawback of this modulation is its high peak-to-average power ratio (PAPR). In this paper, a new modulation scheme of constant-envelope OFDM (CE-OFDM) is proposed. This scheme uses a combination of OFDM, quantizer and continuous phase modulation (CPM) to achieves 0 dB PAPR. The statistical signatures of signals, based on system parameters such as the length of discrete Fourier transform (DFT) and the number of quantization levels are presented. There are two sources of noise in proposed CE-OFDM scheme: quantization noise and channel noise. The theoretical analysis of these noises is... 

This paper proposes a new medium-access control (MAC) protocol designed for wireless sensor networks. A wireless sensor network is an array of large number of sensors interconnected by a multi-hop ad-hoc network. The fundamental objective for sensor network is low-power consumption while latency is usually less important. This characteristic of sensor network motivates different MAC laver design from the conventional wireless network to reduce power consumption. In this paper novel algorithm based on distributed mediation device (DMD) protocol has been introduced that utilized distributed node scheduling strategy to dramatically increase energy saving principally in intermediate devices... 

Flooding technique is widely using to manipulate sensor network essential activities such as synchronization, data gathering, network query and in-network information processing. Reliable and low latency data broadcasting is the primary goal in design of appropriate quality of service aware flooding algorithm. This paper proposes a new error-rate adaptive reliable data flooding strategy. Energy consumption which it the main limitation in sensor network, has been considered in optimal presented scheme. Also the tradeoff between reliability, power consumption and latency has been cared to achieve the finest devise. The simulation results have shown significant enhancement in quality of data...