Dissertation no. 1

Dissertation title	Fabrication of gas nanosensor (natural gas) based on functionalized carbon nanotubes
Student name	Fatemeh Mohammadzadeh		Degree	Master of Science
Field of study	Chemical Engineering		Publish year	2010
Supervisor	Dr.Jahanshahi		Advisor	Dr.Alimorad Rashidi
Abstract	Gas sensors or chemical sensors are attracting a tremendous interest because of their widespread application in industry, environment monitoring, space exploration, biomedicine, and pharmaceutics. Gas sensors with high sensitivity and selectivity are required for leakage detection of explosive gases such as hydrogen and for real time detections of toxic or pathogenic gases in industries. Since the most common gas sensing principle is the adsorption and desorption of gas molecule on sensing materials, it is quite understandable that by increasing the contact interfaces between the analysts and sensing materials, the sensitivity can be significantly enhance. Recent development of nano technology has created huge potential to build highly sensitive, low cost, portable sensors with low power consumption. Among different nano materials, carbon nanotubes show the highest and the best responsing against the exposing gases. Here in this research, multi wall carbon nanotubes are used in gas sensor fabrication. Since functionalizing improve extraordinary the properties of carbon nanotubes, three types of functionalized carbon nanotube through oxidation and amid formation are used as sensitive layers in our sensors. They are: MWCNT-COOH, MWCNT- C12H27N (Dodecylamine) and MWCNT-C18H39N (Octadecylamine). Sensors are designed on CNTs based on two terminal resistors. The target gas is natural gas with 160ppm H2S. Often different parameters are considered in measuring the sensitivity. Here the temperature variation has been chose. The sensing behavior of sensors is interpreted during exposing to H2S for 20 minute and in 25, 40, 50, 60, 800C. Amine functionalized carbon nanotubes demonstrated the highest sensitivity in 25,400C, but in higher temperature carbon nanotubes responded better. MWCNT and MWCNT-COOH have metal and p-type semiconducting behavior respectively. MWCNT-Amines are classified as n-type semiconductors. Although their electrical resistance behavior with respect to temperature changes.

Dissertation no. 2

Dissertation title	Effect of Electrical & Thermal Conductivities on Carbon Nanotubes Synthesis Using Arc Discharge in Liquid
Student name	Asieh Dehghani Kiadehi		Degree	Master of Science
Field of study	Chemical Engineering		Publish year	2010
Supervisor	Dr. Mohsen Jahanshahi- Dr. Mohammadreza Mozdianfard		Advisor	Dr. Gholamreza Vakilinezhad
Abstract	Recently, arc discharge in liquid method has been developed to synthesize several types of nano-carbon structures such as: carbon onions, carbon nanohorns and carbon nanotubes. This is a low cost technique as it does not require expensive apparatus. In this study, production of carbon nanotubes by arc discharge in liquid was investigated using an automated set up equipped with a heat exchanging system. This automatic setup enabled efficient controlling of the gap between two electrodes and maintaining temperature of the solution constant during arc discharge operation. A modified acid treatment was applied for refinement of the nanotubes. Properties and yield of carbon nanotubes obtained by arc discharge in this study was affected by parameters such as: electrical conductivity, concentration, type and temperature of plasma solution, as well as thermal conductivity of the double walled steel beaker. Investigating the crystal structure and morphology of the carbon nanotubes produced using Raman spectroscopy, scanning electron microscopy and transmission electron microscopy showed that the best structure was obtained at the following conditions: voltage 25 volts, a combination of Ni: Mo as a catalyst with a ratio of 1:2 and in a solution with 22/7 mS electrical conductivity, at the temperature of 25ºC. The maximum yield of carbon nanotubes produced at this condition was 6.6 mg, which took place in 0.25 mol solution of LiCl.

Dissertation no. 3

Dissertation title	Synthesis and optimization of alpha-lactalbumin and human serum albumin (HSA) nanoparticles for drug delivery and food science
Student name	Rabeah Mehravar		Degree	Master of Science
Field of study	Chemical Engineering		Publish year	2009
Supervisor	Dr. Saghatoleslami- Dr. Jahanshahi		Advisor	-
Abstract	In recent years, application of protein nanoparticles have became of more and more interest to the food and pharmaceutical industry. Albumin is one of the protein materials that can be used for drug delivering to target site. In this study, alpha-lactalbumin was used to synthesis of nanoparticles by a two-step desolvation process for application in food science. It has significant nutritional properties and is associated with some positive health effect upon consumption. Acetone was added drop-wise for forming alpha-lactalbumin nanoparticles. At the end of process, glutaraldehyde 25% solution was used for preparing nanoparticles as a crosslinking agent. The alpha-lactalbumin nanoparticles were purified by three fold centrifugation (15000g, 20 min). The effect of three parameters was investigated on the nanoparticle size such as pH, temperature and different desolvating agent. The size of obtained nanoparticles was between 35 to 450 nm. In addition, Human Serum Albumin (HSA) was used to synthesis of nanoparticles by desolvation method for application in drug delivery system because of biodegradability, owning high capacity of drug loading and nontoxiticity. Ethanol and glutaraldehyde 8% solution were used as a desolvating agent and crosslinking agent respectively. The HSA nanoparticles were purified by five fold centrifugation (25000g, 10 min). Moreover the effects of different parameters i.e. pH, HSA concentration, agitation speed, glutaraldehyde concentration, organic solvent adding rate, the ratio of organic solvent/ HSA solution were examined in this research. Among these factors, pH, HSA concentration, organic solvent adding rate and the ratio of organic solvent/ HSA solution had the dominate effect on particle size. Taguchi method with L16 orthogonal array was implemented to optimize experimental conditions of the purpose. The best parameters for nanobioparticles production were obtained at pH=9, HSA concentration: 75 mg. ml-1, ethanol adding rate: 1.5 ml. min-1 and the ratio of organic solvent/ HSA solution: 4. Under these conditions the software predicted the 46.625 nm for HSA nanoparticle size, which in experiment 53 nm was achieved for the nanoparticles. Nanoparticles were analyzed by photon correlation spectroscopy (PCS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The image of SEM & AFM demonstrated that the shape of the nanoparticles was spherical. To the best of our knowledge, no reference found in the literature about synthesis of alpha-lactalbumin nanoparticle and using Taguchi method for optimization of HSA nanoparticles up to now and with respect to our study this work is carried out for the first time.

Dissertation no. 4

Dissertation title	Formulation Of Anticancer Drugs Loaded Protein Nanoparticles
Student name	Parvin Golbayani		Degree	Master of Science
Field of study	Chemical Engineering		Publish year	2009
Supervisor	Dr. Jahanshahi		Advisor	Dr. Honari
Abstract	Nanoparticles are colloidal particles, which are less than 0.1 µm in diameter. They have the unique property to accumulate at the site of solid tumors and therefore are very suitable for targeted drug delivery. A number of studies have shown that albumin accumulates in solid tumors making it a potential macromolecular carrier for the site-directed delivery of antitumor drugs.The purpose of the present study was to develop Doxorubicin (Dox) loaded albumin nanoparticles for regional drug release in solid tumors. These Bovine serum albumin nanoparticles were prepared by coacervation method. To characterize the nanoparticles, particles diameter, zeta potential, polydispersity, were determined by Zetasizer 3600 ZEN Malvern UK. The entrapment of Dox in albumin nanoparticles was also determined and in vitro release of drug was studied. Drug release from nanoparticles was observed in PBS. Differential scanning calorimetry method used to understand the thermotropic properties and phase transition behavior. The size of albumin nanoparticles increased after drug loading from Z average of 67 nm to 98 nm for magnetic stirring method and 106 nm for shaking method. The SEM results confirm the uniform shape of these particles. This work has also demonstrated that when Doxorubicin loaded Albumin nanoparticles were prepared, smaller and more uniform nanoparticles were produced at lower temperature. The second conclusion was that the size of drug nanoparticles which prepared by stirring method were smaller than the drug nanoparticles which produced via shaking method. The entrapment of Dox in albumin nanoparticles was also determined 39.45% for magnetic stirring method and 18.58% for shaking method. In vitro release study also shows that Doxorubicin loaded albumin nanoparticles are capable of releasing the drug in a slow sustained manner (almost 30-40% release at the end of 72 hrs).

Dissertation no. 5

Dissertation title	Protein Recovery & Purification in fluidized bed Adsorption
Student name	Mohammad Hassan Shahavi		Degree	Master of Science
Field of study	Chemical Engineering		Publish year	2008
Supervisor	Professor Ghasem D. Najafpour_Dr. Mohsen Jahanshahi		Advisor	_
Abstract	Expanded-bed adsorption (EBA) is a direct approach for primary recovery of proteins starting from unclarified fermentation broths. This process combines centrifugation, evaporation, filtration, and initial capturing of the proteins in a single step. The conventional chemical-engineering view of a fluidized bed is one in which there is a significant degree of mixing, both solid and the fluid phases, e,g, in gas-fluidized systems. In many applications, mixing of the solid phases is desirable for example, in order to obtain high rates of heat transfer and a uniform temperature within the beds used for combustion. But in Expanded Bed Adsorption mixing is an undesirable factor which disturbs the process efficiency. The purpose of this research was to investigate the effect of structural parameters such as column diameter, settled bed and expanded bad height of adsorbent, on mixing in the bed residence time distribution (RTD) studies using acetone tracers. Experimental data were obtained in this work to show an apparent increase of axial dispersion with an increase in column diameter. It has also been shown that expansion effect up to 1.3 times the settled bed height, was insignificant, but expansion higher then 1.3 time the settled bed will disturb the mixing and consequently the adsorption efficiency. Finally the effect of mixing on protein adsorption has been considered using the tow model proteins, egg albumin (EA) and bovine serum albumin (BSA). The experimental data showed that proteins adsorption model using an apparent decrease of adsorption efficiency with an increase in mixing.