Sharif Digital Repository

Polyethylene is the most widely used plastic material in the world for reasons such as lightweight, good strength, good processability, low cost, and low maintenance cost, and very good chemical resistance. One of the applications of polyethylene that has received much attention in recent decades is its use in the manufacture of hot water pipes. To maintain the properties of polyethylene at high temperatures, it must be crosslinked at a proper level. Appropriate antioxidants should be used to prevent the degradation and oxidation of polyethylene during the process as well as long-term operation. Concomitant use of phenolic antioxidants for long-term stability during service and phosphorus... 

This thesis is going to investigate the ontological foundation of Science and Tool. To this aim, it refers to Heidegger’s works especially the Being and time. Heidegger gets involve in analyzing Science in the Being and Time. He emphasizes on importance of establishment of a fundamental knowledge which should ontologically recognize basic concepts and methods of Sciences, to cause a real progress in sciences. Heidegger also asserts that the Mathematical interpretation of the world is not a fundamental, and it must be replaced with phenomenological interpretation, which clarifies the ontological foundation of the theoretical view, and regards to all aspects of world’s existence. In this... 

In this treatise, it will be shown that the subject of faith is the subject who loves God and in showing her love to God, she sacrifices her dearest things in the world. By doing that, she would free herself from everything that mind herself. She doesn’t do this action to be given a better reward by God. Her motivation for performing this action is nothing but love. Meanwhile, the subject of faith hopes God to respond to her love and engage in an I-Thou relationship with her. Now, her hope would be justified when God plays an active role in the world and admires her action, i.e., when eros can be attributed to God  

Dispersed phase holdup has been measured in a 75 mm diameter pulsed disc and doughnut extraction column for three different liquid-liquid systems. The effects of operational variables such as pulsation intensity and dispersed and continuous phases flow rates on holdup have been investigated and found to be significant. The existence of three different operational regimes, namely mixer-settler, dispersion, and emulsion regimes, was observed when the energy input was changed. The results indicated that the characteristic velocity approach is applicable to this type of extraction column for analysis holdup in transition and emulsion regions. Empirical correlations are derived for prediction of... 

Uranium separation from other metals in ore and nuclear waste is one of the most important stagesin nuclear fuel cycling. Solvent extraction is the common method for uranium extraction that reagent plays important rule in this technique. In this investigation, uranium solvent extraction is carried out by Cyanex 301 as reagent from nitric acid. At beginning, equilibrium batch extraction was carried and the effect of parameters such as pH, reagent concentration, temperature, shaking time of two phases, volumetric ratio of two phases, diluent and nitric acid concentration on extraction was investigated and optimum value of parameters was calculated. Uranium concentration effect was also... 

In the current work, jatropha oil was studied in the hetrogenious solid catalytic transesterfication reaction. For this perpous, KOH/CNT catalyst which was prepared by dry impregnation method was used. SEM, XRD and TGA were applied for the catalyst characterization. The results showed that for the KOH/CNT catalyst, by increasing the loading of KOH, the activity of the catalyst increased and the most active catalyst was prepared by 20% loading of KOH. The optimum conditions for transesterfication reaction in the percense of this catalyst were: 4.7% catalyst weigth and the 24.5 molar ratio of methanol to oil and also the reaction time of 2 houres which the rate of reaction at this time is...