Sharif Digital Repository

Membrane processes are accounted as the newest technology for gas separation and nowadays are more applicable in different petroleum, gas and petrochemical industries because of abundant advantages. One of important application of membrane gas separation technology is syngas adjustment and hydrogen enrichment. In this research, the appropriate alumina nanocomposite membranes for this purpose are prepared and their gas separation performance is investigated. Therefore the mixed matrix membranes, containing the continues polymeric phase polyethersulfone and dispersed phase alumina nanoparticles is synthesized by using methods of experimental design. As the best of our knowledge, there is no... 

This thesis studies the possible solution to the H0 tension via a dynamical systems approach. The early dark energy (IDE) scenario can somewhat alleviate the Hubble constant tension. On the other hand, postulating a new subdominant EDE in the pre – recombination Universe can also resolve the H0 tension. We introduce a novel model to interweave the early dark energy(EDE) and interacting dark energy-dark matter (IDE) scenarios. In this scenario, the early dark energy emerges naturally by changing the topological class of the phase portrait of the universe dynamics. In particular, an EDE component contributing only 10% of the matter density of the Universe—preferably in the vicinity of the... 

Austenitic stainless steels are the most common kinds of stainless steels. Although these alloys are generally very weldable, there are some problems in join- ing of them using fusion welding. Solidification and liquation cracking or corrosion at grain bound- aries in the heat-affected zone are examples of these problems. Transient liquid phase (TLP) bonding is an important variation of diffusion bonding that has the potential to overcome this problems. Two-step TLP bonding is an ingenious development to form non-planar interface. This method consists of a short-time high temperature heating to melt interlayer followed by isothermal solidification of liquid phase at a lower temperature. In... 

Temerature fluctuation of the Cosmic Microwave Background (CMB) is one of the key observebles of the modern cosmology. Today, it is widely believed that quantum fluctuation that are stretched to horizon scales during a period of acceleration expansion -- at the onset of evolution of the universe-- are responsible for these perturbations. In the simplest scenarios of the inflation, a scalar field is responsible for both nearly expansional expansion of the universe and the proimordial fluctuations. In this thesis, we investigate the models of inflation with an additional light degree of freedom. In particular, we employ the method of the Effective Field Theory to study the general structure... 

By studying of simulations, it can be seen that the linear point (LP), a point lies midway between the scales associated with the peak and the dip in the correlation function on BAO scales, is a useful window into cosmology and large scale structures rather than baryonic echo peak. Some fundamental features of the LP, been unaffected by redshift space distortions and gravitational non-linear effects, has made it important. I want to find evidences to stability of the LP by utilizing Standard Perturbation Theory through my thesis  

Considering the wide applications of 304 stainless steel in various industries and the existing literature on transient liquid phase bonding of stainless steels with a variety of interlayers, the present work aimed to reduce the bonding time by using a two step bonding method. Faster bonding reduces both energy consumption during bonding and the base metal grain growth. It also leads to a lower reduction in the base metal and joint strength.Due to the melting point of the interlayer, different durations and a temperature of 1200°C were selected for the first step. This temperature was maintained for a specified period of time before it sharply dropped to and remained at 1180°C (the... 

Some widely used drugs such as paclitaxel (PTX) are poorly water soluble. The clinical use of PTX with solubilizer causes side effects. These problems limited its application in treatments. In this work has been studied the effect of β-CD-g-PG (HPCD) hybrid nanomaterials, conjugated PG branches onto β-CD core, on the water solubility of PTX. First HPCD has been synthesized. Then the inclusion complex of PTX with HPCD was prepared. The inclusion complex efficiency for PTX:HPCD complex in 1:25 mole ratio was 87%. Then solubility of PTX with HPCD in water has been determined, showing Ap type phase solubility diagram. Then stability constants were calculated. The first order and second order... 

Simultaneous detection of pH and glucose levels in sweat is a promising tool for early skin disease detection and diabetes diagnosis. Hydrogels have attracted a lot of attention in the field of wearable biosensors due to sweat absorption capability, biocompatibility, and the ability to store enzymes and reagents in their cavities. In this research, we have presented an innovative wearable colorimetric biosensor based on polyvinyl alcohol (PVA) hydrogel, which can simultaneously measure pH level (in the range of 3-9) and glucose concentration (in the range of 0.025-0.5 mM) of sweat with the help of machine learning (ML). This wearable sensor consists of two main parts: sensors and a patch, in...