Sharif Digital Repository

During the past decades, structural parameters are used as a tool for studying the formation and evolution of galaxies. Sersic parameter is one of these parameterswhich also known as shape parameter. Sometimes, measuring such parameters depend on the observed wavelength. So far, this dependence has been rarely attended. In this thesis we are trying to know how and why these parameters depend on the wavelength  

Functional design of coating system for the primary mirror of the Iranian National Observatory (INO) is done. This telescope has a 3.4 m primary mirror in diameter, made of Zerodur from Schott. Although similar coating systems are in use since years ago, this is the first attempt to design a system for such a large surface case in Iran. Systematic approach led us first to clarify and identifying the design requirements. Lower limit of 80% for reflectance on all wavelength range from 325-1000 nm, thickness of 100 nm with un-uniformity of 5 nm, adhesion enough to pass the selotape test and surface roughness of less than 8 nm. Study of the available methods for coating and selection of the best... 

The luminosity gap between the two brightest galaxies of the galaxy groups and clusters is a statistics criteria for studying the time of the formation of these gravitational systems. So far, the luminosity gap of galaxy systems is studied in local universe (z~0). This parameter is a good criteria to understand the structure formation models. In this project we investigate the evolution of luminosity gap statistic in high redshift universe (z~0.4). The evolution of luminosity with redshift is a proper tool for investigating the evolution of galaxies in different environments during the time  

We study the fundamental and the photometric plane of a sample of 50 dwarf galaxies within the core of Coma cluster observed with DEIMOS on Keck II down to R-band luminosity of -15 Magnitudes. The Calcium triplet lines in the wavelength range between 7500 to 10,000 ˚A, allow us to obtain the velocity dispersion for the sample galaxies with high precision. We also performed a comprehensive error analysis to better estimate the uncertainties of this key observable. We also carried out a galaxy structure modeling using the ACS I-band images for a larger sample. We found larger velocity dispersions for fainter dwarfs than what expected from mass-luminosity trends of brighter Coma galaxies. In... 

We present a new high signal to noise ratio spectroscopic survey of the Northern hemisphere to probe the Local Bubble and its surroundings using the 5780Å and 5797Å Diffuse Interstellar Bands (DIBs). We have observed 432 sightlines to a distance of 200 pc over a duration of 3 years. In this study, for both inside and outside the Local Bubble, we establish the 5780and 5797correlations with Na i, Ca iiand E(B-V). The correlations show that among all neutral and ionized atoms, the Na ihas more similarity with 5780and Ca iihas strong correlation with 5797, which suggest that the ionization level of 5797is more than 5780. We study the 5780correlation with 5797, which shows a tight correlation... 

Fossil galaxy groups, famed to have undisturbed inter-galactic gas due to lack of recent group scale mergers, are energetically and morphologically ideal environments to study the IGM heating. In this article, we study the role of active galactic nuclei in heating the IGM in a sample of five fossil galaxy groups by employing their GMRT observations at 610 MHz and 1.4 GHz. We find that only two of the dominant galaxies in fossil groups are associated with the radio lobes. We evaluate the PdV work of the radio lobes and their corresponding heating power and compare to the X-ray emission loss within cooling radius. Our results show that the power due to mechanical heating is not sufficiently... 

The main question of this thesis is if and to what extent does the Social Security retirement benefits cause early retirement. This is important because the more individuals are willing to retire earlier, the larger are the Social Security liabilities to pay the retirement benefts, and also it means that more people are leaving the labor force, hence a lower labor force participation. The research was conducted on a sample of men extracted from the Social Security Or-ganization data sets, employing Option Value and Peak Value models to estiamte a binary choice model. The results indicate that Social Security (in the form of retirement benefits) have a significant effect on retirement ... 

Pricing plays an important and essential role in the profit and income of companies. The importance of pricing is not only related to its role in the company's profitability, but it also changes the customer's understanding and loyalty towards the company and can create the company's reputation or destroy it. Determining the right price will increase product sales and increase customer loyalty and create a competitive advantage for the company. One of the most important and influential variables in product pricing is the amount of demand. The main challenge of companies for product pricing is the uncertainty in their demand. In order to deal with this problem, data-driven pricing is used.... 

Due to the importance of using pure proteins in the industry and basic research in order to study them in the structural contexts and interactions of proteins in recent years, purification methods have been extensively developed. The purification steps usually depend on the size of the protein, its physical and chemical properties, the binding affinity and the biological activity of the protein in question, In the purification process, the protein portion is separated from the non-protein portion. The biggest challenge is when we want to separate different proteins. Different chromatographic methods are used, depending on the properties of the impure proteins. One of these chromatographic... 

The approach of this thesis is to develop and simplify robust microextraction techniques and apply these developed methods to real samples and complex matrices. Firstly, a modified solvent microextraction with back extraction method (SME/BE) combined with high performance liquid chromatography and fluorescence detection (HPLC-FD) was developed for the determination of citalopram in human plasma. Extraction process was performed in a home-made total glass vial without using a teflon ring, usually employed in SME/BE. The evaluation results demonstrated that the calibration curve showed linearity in the range of 1.0–130.0 ng/mL which covers therapeutic window and even lower amounts which is... 

In this study, a newly designed needle trap device (NTE) containing modified nanosilica as sorbent is used for sampling and preconcentration of some polycyclic aromatic hydrocarbons (PAHs) from headspace of aqueous solutions. An inexpensive modifier, cis-9-octadecenoic acid (oleic acid), which contains a long chain, was used to modify the surface of the nano-scaled silica particles. The hydrophobic interaction between oleic acid and aromatic compounds was the preliminary evidence for extraction of these compounds. After adsorption of selected compounds, thermal desorption was, subsequently, employed to transfer the extracted analytes into a GC–FID. Extraction time and temperature, flow rate... 

Liquid-liquid-liquid microextraction (LLLME) is a new miniaturized liquid extraction to preconcentrate and purify for ionizable analytes. In LLLME firstly analytes extracted in an organic phase, and subsequently back-extracted into a second aqueous phase. Main advantages of LLME are their speed, simplicity, negligible volume of solvents, analytical precision, short sample preparation and low cost. This technique was shown to be an efficient preconcentration method for the extraction of estrone and estriol from biological samples. A basic microdrop in the tip of microsyringe was fixed in the organic layer over the sample solution. After extraction for a preset time, the microdrop was... 

In this study new magnetic solid phase extraction (MSPE) methods based on Fe3O4 magnetic nanoparticles (NPs) for extraction and preconcentration of oxadiargyl and fuoxetine from aqueous and biological samples were developed. In the first work, Fe3O4 NPs was successfully used as a magnetic nano-sorbent in magnetic micro-solid phase extraction (M-µ-SPE) of oxadiargyl, a newly used pesticide, from environmental water samples prior to gas chromatography-mass spectrometry determination. Oxadiargyl in mild acidic condition has tendency to be adsorbed on Fe3O4 NPs surfaces. Most important parameters that affect the extraction efficiency were also studied. Under optimized condition, the proposed... 

A novel application of diazonium salts for grafting the sol-gel based sorbents was sucessfully introduced. Preparation of unbrekable sorbents has been on highly demand and sough after by many researches for several years. However, there are a few achivements in this regard, but it still remains as a big challenge.Regarding to this issue, diazonium salts were sucessfully applied for functionalizing the different substrates, in which there is no limitation in selection of substrates. Different substrates, metallic and non metallic, such as copper, brass, stailess steel and PTFE were chosen to be functionalized by chemical or electrochemical reduction of 4-Amino phenyl acetic acid. Then,... 

In this study, a novel electrospun modified polyamide (PA) based nanofibers were synthesized and employed as fibers coating for rapid determination of chlorophenols. The major polymer solution contained PA along with polyethylene glycol (PEG), acting as a side low molecular weight polymer. After production of the PA−PEG fiber coating, PEG was subsequently removed and modified by water which was confirmed by Fourier transform infra-red spectrometry.The scanning electron microscopy images showed anaverage diameter of 640 and 148 nmforPA and PA−PEG coatings, respectively while the latter coating structure was homogeneous and porous.The extraction efficiency of unmodified and modified coatings... 

In the present work, the combination of single drop liquid phase microextraction and gas chromatography-mass detector (GC-MS) was used for determination of pesticides, Clodinafop, Haloxyfop and Fenoxyprop in natural water samples. a novel techniques based on SDME for develop in which solvents with higher density than water was successfully used. this technique could overcome some limitations of conventional SDME such as instability of organic droplet and limited stirrer rate in which result increasing the mass transfer rate and extraction efficiency. Experimental liquid phase microextraction (LPME) conditions, such as extracting solvent, stirring rate, micro drop volume, extraction time, pH... 

An on-line solid phase extraction (SPE) method coupled with high performance liquid chromatography (HPLC) was developed using electrospun polyamide (PA) nanofibers as the extractin medium for trace determination of clodinafop propargyl herbicide in environmental aqueous samples. The sufficient numbers of disc sheets were cut from the electrospun PA mat and used as packing material in a cartridge. The homogeneity and the porosity of the prepared PA sheet were studied using the scanning electron microscopy (SEM) and the observed nanofiber diameters and lengths proved that the prepared sorbent possess a high aspect ratio. Major parameters affecting the extraction efficiency were optimized. The... 

Novel electrospun nanofibers and their applications as the microextractionsorbents are the centre of this research. Polymeric nanofibers with diameter in the scale of nano-to-micro were prepared by the electrospinning method and employed for microextraction purposes. Two major microextraction methods included solid phase microextraction (SPME) and micro-Solid phase extraction (µ-SPE). In the first work, a novel SPME fiber was fabricated by electrospinning method. A thin stainless steel wire was coated by the network of polymeric nanofibers. The polymeric nanofiber coating on the wire was mechanically stable due to the fine and continuous nanofibers formation around the wire with a three... 

A novel Fe3O4/poly (aniline-naphthylamine) (ANI-NA)-based nanocomposite was synthesized by chemical oxidative polymerization process as a magnetic sorbent for magnetic solid phase extraction. The extraction efficiency of this sorbent was examined by isolation of rhodamine B (RhB), a mutagenic and carcinogenic dye from aquatic media in dispersion mode. The efficiency of the synthesized Fe3O4/copolymer composite was examined and compared with Fe3O4/polyaniline (PANI) and Fe3O4/polynaphthylamine (PNA) by quantification of RhB using spectrofluorimetry. Among them, Fe3O4/poly (ANI-NA) nanocomposite showed a prominent efficiency. The scaning electron microscopy (SEM) image of the synthesized... 

A simple, fast and sensitive method based on microextraction in packed syringe (MEPS), a new format of solid-phase extraction (SPE), as a sample preparation technique in off-line combination with gas chromatography-mass spectrometry (GC-MS) was developed. Polyaniline (PANI) nanowire network was synthesized and used as sorbent of MEPS for the multiresidue determination of selected analytes from triazine, organochlrorine and organophosphorous pesticides in aqueous samples. The PANI nanowires network was prepared using soft template technique and its characterization was studied by scanning electron microscopy (SEM). The use of micelles in this methodology has an important role in the shape of...