Sharif Digital Repository

A series of poly(ethylene-co-vinyl acetate) (EVA)-based hot melt adhesives containing either a raw rosin or a hydrogenated rosin ester have been prepared to investigate variation of viscosity, softening point and peel adhesion with composition. Adhesion of the prepared hot melt adhesive to the substrate was characterized by T-peel strength test. Increasing rosin had a prominent effect on the adhesion. Viscosity decreased and softening point increased as the wax content increased. Addition of zinc borate as a flame retardant decreased T-peel energy and increased the viscosity and softening point of the samples. Higher peeling strength accompanied with a good softening point and viscosity... 

Transdermal drug delivery systems are products which are known to have ability to pass drugs through the skin and into the blood, so medicine effects appear as a result. During the past two decades, many scientists interested in drug delivery through the skin. Constant blood plasma level and avoiding first-pass metabolism are advantages of this system compared to oral and intravenous systems. The biggest problem in the development of these systems, is impermeability of Stratum corneum, the outermost layer of the epidermis. In this study, design and evaluation of in vitro transdermal drug delivery system for granisetron serve as treatment of nausea and vomiting was performed. For this... 

Obstruction of Left Anterior Descending artery (LAD) due to thrombosis or atherosclerotic plaques is the leading cause of death world–wide. Targeted delivery of drugs through micro- Nano-particles holds noteworthy promise which can make clot busting or the restenosis treatment with minimal toxicity possible. In this work, Fluid-Structure Interaction (FSI) simulations of blood flow through a patient-specific reconstructed geometry of LAD artery have been conducted using a non-Newtonian hematocrit (HCT) dependent model for blood. Based on physiological facts, 25, 45 and 65 percentages of HCT were assumed as acceptable representations of anemic, healthy and diabetic blood conditions,... 

The purpose of this study was to create a three-cationic electro phosphate coating of zinc-nickel-manganese by cathodic method and to investigate the effect of operating variables on the properties of zinc-nickel-manganese tri-cationic electro phosphate coating. Hence, the effects of variables such as coating acidity, coating thickness, coating temperature, coating time and concentration of manganese were studied in the bath on the properties such as coating morphology, corrosion resistance, coating thickness. Coating morphology was characterized by scanning electron microscopy and corrosion resistance by polarization test. The pH values of 1.4, 1.8, 2 and 2.2 were selected, and the results... 

A finite element model for seismic analysis of concrete arch dams is proposed. Material inelasticity as well as joints nonlinearity is considered. In order to provide a precise description of concrete response, a novel plastic-damage constitutive model for plain concrete is developed. For this purpose, the microplane theory is proposed for overcoming the deficiency of available anisotropic continuum plastic-damage models in reproducing the true anisotropic nature of damage in multidimensional loadings.Based on the microplane theory, the degeneration process in concrete is considered along with plastic deformations. Using the principle of strain energy equivalence, a transformation between... 

We propose a model for friction between two rough surfaces based on extreme value statistics (EVS). Different models for single-asperity contact, including adhesive and elasto-plastic contacts, were combined with EVS. The Hertzian model for contacts and Gumbel distribution for summit heights show the closest conformity with Amonton’s law. The range over which Gumbel distribution mimics Amonton’s law is wider than that of the Greenwood–Williamson (GW) model. In comparison with other EVS distribution, Gumbel distribution seems the proper choice for summit‘ s height. Interestingly, here again, elasto-plastic contact and Gumbel distribution for summits achieve the best conformity with Amontons... 

Today, the cleaning and moss removal of the hulls of ships is very important due to the strict and international laws of reducing pollutants and the exorbitant cost of fuel of the country's navy. The advantages of cleaning the hull of vessels are reduced fuel consumption, increased ship speed and longer hull life. Traditionally, the hulls are cleaned by divers, and in recent years the use of crawling robots has been welcomed by the industry because of its benefits. This important thing in Iran is still done by divers and therefore the need for indigenous development of such robots in the country is felt.In the present study, the aim is to design and build a reliance system for the ship's... 

Creating sustainable development in today's human societies is essential, one of the pillars of achieving this important goal is environmental protection. Thus, waste management as a new challenge is leading engineers. Lead-acid battery waste is one of the sources of environmental pollution. Lead-acid battery separators contain 50% recyclable nanosilica. The main challenge of recycling nanosilica from separators is the presence of significant amounts of 6 to 9% wt.% of lead and 5% by weight of other impurities. Therefore, in the present study, lead trapped in the separating pores is removed using mechanical washing or abrasive washing. Then, the quality of recycled nanosilica is evaluated... 

Ice formation upon various surfaces could lead to many industry problems and result in unpleasant accidents. For instance, the formation of ice on wind turbine blades or airplanes/helicopter wings could cause catastrophic disasters. The methods used to address this problem usually require exogenous energy consumption or anti-ice ingredients. The energy or anti-ice ingredients usage has adverse environmental effects and should be replaced with better approaches. One of these approaches is utilizing modified anti-ice surfaces. In this method, by modifying surface features, such as physical asperities and surface energy, the icing time of the surface could be prolonged. These surfaces are...