Sharif Digital Repository

In the recent years, sensors and biosensors attracts much attentions as a suitable devices in analytical chemistry. In this meantime carbon nanostructures and metal nanoparticles act as a good choice owing to their unique properties such as high electrical conductivity andmechanical and chemical stability in modification of the surface of sensors and biosensors. Because of importance of analysis the trace amounts of pharmaceutical and biological compounds, in this studies the surface of glassy carbon electrode was modified with some carbon nanostructures and metal nanoparticles for electrochemical investigation and determination of pharmaceutical and clinical compounds.In the first work, a... 

Phosphating is one of the most procedures as a final surface treatment or pre-treatment (lubrication and Infrastructure color) is done on ferrous and nonferrous alloys. Phosphate coating on the wire drawing, increase speed of drwing, increase die life, increased resistance to abrasion caused by the friction reduction, reduced maintenance costs and improved surface appearance are combustible and conditions. The aim of this study was to evaluate the effects of variables such as temperature, pH bath, the coating bath components concentration on coating properties and optimize calcium zinc phosphate coating on steel wire, for better lubrication and decrease friction in the wire drawing process.... 

Nowadays, due to various reasons awareness of environment preservation has increased throughout the supply chain. So supply chain owners revise their carbon footprint. Among different methods of reducing, operational decisions (e.g. ordering quantity or transportation method) has less cost and time for observing outcomes. Our main focus is on inventory models that taking account environment considerations especially carbon emissions. Through these models, vendor-managed inventory model for reducing total cost of chain gets more attention than past. The purpose of this work is to develop a two echelon supply chain with multi-item for replacing inventory. This model includes warehouse capacity... 

Chemical dispersants applied to the surface of Persian Gulf during the oil spill in 2010 were more than one million gallons. Following the addition of dispersants, oil mixes below the seawater surface and can be degraded or dissolved into the water column. The aforementioned condition is a perfect opportunity for degradation of organic pollutants using Ultraviolet light emitting diodes Advanced Oxidation Processes (AOPs). These methods are based on activation of oxidants such as persulfate and hydrogen peroxide to generate extremely reactive radicals. Dispersants would increase the degradation rate by providing more active area (homogenous solution) for these radicals. AOPs have shown to... 

Energy consumption and pollutions especially carbon dioxide emissions are two of the main challenges in the cement industry. 5-7 percent of world’s carbon dioxide emissions is due to cement production while 900 kg of carbon dioxide is emitted for the production of a tone of cement. The main source of carbon dioxide emissions in a cement plant is the combustion of fuel to provide heating demands and also converting the ore into clinker. Therefore, any improvement in energy efficiency in a cement plant could reduce carbon dioxide emissions resulting from the combustion. Important ways of energy recovery in a cement plant are using the energy recovered from the exhaust gas in the preheater... 

Characterization and simulation of carbon nanotube-reinforced composites at large scale have been a concern of researchers in the past decade. This is due to the computational complication of considering many embedded carbon nanotubes (CNTs). However a simple meshing of organized CNT distribution in the matrix can ease this obstacle. In this study, a finite element approach is employed to investigate the elastodynamic behavior of a wavy CNT-reinforced composite structure. A three dimensional structure with up to 6400 uniformly distributed wavy CNTs is embedded in a polymer matrix. Each wavy nanotube is represented by a set of beam elements. The effect of nanotube waviness and volume fraction... 

The electrochemical oxidation behavior of the anti-inflammatory drug piroxicam was investigated. A carbon nanoparticle (CNP)-chitosan (CS) film-coated graphite electrode (PGE) was fabricated and the electrochemical behaviors of piroxicam on its surface was investigated by the means of cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). In comparison to the bare PGE, at the surface of the CNP-CS film modified electrode, the oxidation peak current of piroxicam increased significantly and the peak potential shifted negatively. Consequently, a simple and sensitive electroanalytical method was developed for the determination of piroxicam. The... 

The present work describes sensing application of modified TiO2 nanotubes towards detection of dopamine. The TiO2 nanotubes electrode was prepared using anodizing method at different conditions, among which NaF/ NaHSO4 solution and voltage of 15 V was chosen as the optimum condition. In order to improve the performance, surface modification with metal nanoparticles (Pd, Pt and Au) and carbon is required using “pulse electrodeposition” and “decomposition of polyethylene glycol at 600 °C” respectively. Carbon was deposited by decomposition of polyethylene glycol in a tube furnace to improve the conductivity. In this regard two type of electrodes were proposed: Pd-Pt-Au-TiO2 and C-Ni(Pt)-TiO2.... 

Based on International Energy Agency studies, achievement of 450 ppm CO2-equivalent emission target in global emission means that the CO2 emissions in 2050 must be reduced to %50 of 2005 level, and this implies that a portfolio of emission reduction policies and strategies need to be exploited through current century.
At the present time, Carbon Capture and Storage (CCS) Technology is a dominant strategy among all the long-term carbon abatement strategies in many countries. Nevertheless, its potential as a climate mitigating option will be proved, only if it is implemented in the countries which are developing at a great pace and taking advantage of fossil fuels in order to afford their... 

In This article, we aimed to estimate impact of dual sourcing strategy on environmental implication and show how this strategy can ameliorate the emission of greenhouse gases. For this purpose, first we define comprehensive NLP models for splitting order problem with carbon emission cap and carbon emission Trade-Cap policy. Then customized sequential quadratic programming approach had been developed for solving these models. In addition, customized Genetic Algorithm validated this approach. Finally numerical results show that order splitting strategy cause to reduction in costs and emission at same time. Beside this outcome, we show the so-called Trade- Cap policy almost performs better than... 

Metal foams are considered as a group of new materials and are applied widely in various areas due to their particular properties such as low density, high strength-to-weight ratio and appropriate mechanical, thermal, physical, electrical and magnetic properties. The aim of the present study is acquiring the technical knowledge of Zinc foam production by melting route and also optimizing the effective parameters on the foam stability. For this reason, 4 Zinc foams were produced at different times and temperatures. The amount of Calcium as the melt fluidity reducing agent and Titanium hydride and Zinc carbonate as the blowing agent were the same in all the specimens. The effect of heat... 

In recent years, using the nanoparticles has caused a great revolution and development into the materials structure and the polymer science developed corresponding to important role of it in consumer goods. So Carbon Nano Tubes (CNTs) belonging to the precious physical, Mechanical and thermal properties has been studied. The CNT is mixed by mechanical and solution methods with elastomeric matrix. In this research the mechanical method used, because of industrial applications. Although, there are many challenges against dispersion owing to weak cohesion between CNTs and matrix in the mechanical method. The progress in rubber composites reinforced by CNTs and other reinforcement and as well as... 

Epoxy resins are relatively brittle and have low resistance to crack propagation. It is common to add rubber particles to improve crack resistance in epoxies, although these particles may deteriorate the strength of the matrix. Different nanomaterials are used to overcome the inherent brittleness of epoxies and to keep the mechanical properties. Among them, carbon nanotubes has been attracted many attentions. Fractue behavior and mechanical properties of two kind of novel nanocomposites, i.e, epoxy/carbon nanotube and epoxy/rubber/carbon nanotube are investigated in current study. Electron microscopy investigations were done to assure the CNTs distribution and fracture mechanisms as well.... 

In most cases, material failures occur on their surfaces, such as fatigue fracture, wear and friction, fretting fatigue and corrosion, so surface modification is one of the most effective techniques to improve the strength of materials. Correction of near surface grain size to nanoscale is one of the effective ways to improve the strength, fatigue life, toughness and etc. With increasing evidences of novel properties in nanostructured materials, it is reasonable to propose to achieve surface modification by the generation of nanostructured surface layer so that the overall properties and behaviors of the material are significantly improved.By means of surface severe plastic deformation, the... 

TiO2 has been considered the most promising photocatalyst for the degradation of pollutants in air or water; however, it shows poor absorption of visible light and requires ultraviolet (UV) light for activation. We have successfully synthesized a visible-light-active carbon and nitrogen and yttrium tridoped TiO2 catalyst. In this study, Nanocrystalline photocatalysts of TiO2 doped with yttrium, codoped with carbon and nitrogen and tridoped with carbon and nitrogen and yttrium were prepared by the sol–gel method and investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy ( DRS), Scanning electron microscopy (SEM/EDS) and... 

In recent years, the light metal matrix composites with high specific strength have attracted great interests in electronics, aerospace, automobile,and medical industries. Additionally, employing sever plastic deformation is a matter of interest in industries in order to gaining micro and nano microstructure, and hence, proper mechanical properties. Considering two mentioned facts, in this project, the effects of sever plastic deformation parameters carry out by equal channel angular press on mechanical and microstructural properties of Magnesium AZ91-Carbon Nanotube composite are investigated.To do this, first the samples of mentioned composite were produced by casting, then their... 

Since the discovery of nanomaterials, the nanotubes have found special considerations. The high strength beside the low density, have attracted the interest of the scientists and engineers. Nowadays, one of the common methods to produce composites with high specific strength is to utilize of the nanotubes in the matrix of lightweight metals and alloys such as magnesium and aluminum. Recent researches indicate that very limited focus has been given to the production and properties of the magnesium - carbon nanotube composites and their workability. In this research, magnesium alloy - carbon nanotube composite is produced by casting method and its strength and workability are investigated as... 

Concrete is the most used man-made material on earth, albeit is responsible for the ten percent of the carbon dioxide gas emitted by human to atmosphere. Also the most important constituent of concrete, hydrated cement, has a sophisticated structure yet its precipitation, composition, mechanical properties and morphology has been the subject of dispute among cement researchers. On the other hand, according to the increasing focus on sustainable development, design of optimum materials has become important. Several models have been proposed for the structure of cement hydrate while every model has its own advantages and disadvantages. Recently, a combinatorial model at atomic scale has been... 

Strong van der Waals (vdW) potential fields of carbon nanotubes (CNTs) makes them capable to encapsulate some nanostructures inside their hollow space, which leads to the construction of new hybrid nanostructures under specific conditions. Carbon nano-peapods, carbon nanowires and the hybrid of DNA and CNT are the main categories of hybrid nanostructures of CNT. Characteristics of hybrid nanotubes are unique and different from those of CNT. In nanostructures, the lattice spacing between individual atoms is considerable with respect to the structural dimensions. Also, the range of internal characteristic length is relatively close to external ones. So that utilizing the classical continuum... 

In the present study, multistage strain aging phenomenon using rolling pre-strain and solution treatment at 680℃ for 40 min was used to study the effect of temperature and inter-pass time (IPT) on the static strain aging behavior of a low carbon steel sheet. The increase in hardness and strength caused by work hardening and the aging at each pass were separately calculated.The samples were rolled and subjected to aging process both in a single pass of 20% rolling reduction in thickness and in four stages consisted of 5% reduction at each stage. The mechanical properties of the samples aged at different time and temperature, were compared. In order to evaluate the effects of pre-strain type,...