Graduate School of Natural and Applied Sciences
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thesis.listelement.badge ANALYZING THE EFFECT OF DOXYCYCLINE AND GENTAMICIN ON SELECTED CYTOSOLIC ENZYMES(2022-02-24) ALI, JUNAID MOHAMMED; İşgör, S. Belgin; İşgör, Yasemin G.Gentamicin and Doxycycline are antibacterial drugs commonly utilized in a treatment of Gram positive and Gram negative bacterial infections. They have been used in this study to evaluate their effect on antioxidant enzymes such as Catalase (CAT), Superoxide Dismutase (SOD), Glutathione-S-Transferase (GST) and Glutathione Peroxidase (GPX). Each of these drugs are water soluble and shown to be stable when tested in vitro for three months at concentration of 1mg/mL under + 4 ºC and – 20 ºC via UV/VIS spectrophotometer. In this study, several serial dilutions of drug solutions were applied according to enzymatic assay protocols to measure the activities of these enzymes. The comparison of obtained results with the control (zero concentration of drugs) didn’t show any significant effect on each of the enzymes under study. From the observed results, 15% of CAT, 5% of GST activities were inhibited and no effect on GPX and SOD were observed in this study.thesis.listelement.badge ANION EXCHANGE MEMBRANE BASED ON SEMIINTERPENETRATING POLYMER NETWORK OF POLYETHER SULFONE / QUATERNIZED STARCH FOR ALKALINE FUEL CELLS(2022-01-11) ALMURUMUDHE, OSAMAH KADHIM HILAL; Güler, Enver; Alsalhy, Qusay F.Many effective devices that emerged and developed to generate power without toxic emissions. Proton exchange membrane fuel cell (PEMFC) is one of these effective devices. Its fully dependence on platinum as electrocatalyst has limited its application in a highly competitive market. Potential use of non-precious metal catalyst makes anion exchange membrane fuel cell (AEMFC) garnering renewed attention. Anion exchange membrane (AEM) is considered as the heart of the (AEMFC) and at the same time the preparation as the biggest challenge in the development of (AEMFC). Fabrication of those AEMs with high conductivity and with high alkali resistance has become an active research area for investigation. In this work, two types of anion exchange membranes for alkali fuel cells have been fabricated according to a simple and novel strategy by single step quaternization ̸crosslinking of starch with choline chloride and epichlorohydrin then blending it with polyethersulfone resulted in a semiinterpenetrating polymer network. The first type, the porous polyether sulfone AEM with 133.33 µm thickness exhibited water uptake of 376.7% and swelling ratio of 5.3%. The second type, the dense polyether sulfone AEM with 55.48 µm exhibited water uptake of 69.9% and swelling ratio of 7.5% The charaterization results confirmed that our fabrication route was very successful and our fabricated AEMs are very promising candidates for alkaline fuel cell applications.thesis.listelement.badge ANTIOXIDANT POTENTIAL ANALYSIS OF COLUMN CHROMATOGRAPHIC FRACTIONS OF EUPHORBIA PLANT EXTRACT(2022-02-25) Elkouha, Muna Zuam Emhemed; İşgör, S. BelginThe aim of this study was to assess quantity determination of Polyphenols (Total phenolic content; TPC, Total flavonoid content; TFC) and evaluate antioxidant potential of Euphorbia macroclada Boiss. leaves extract followed by their effect on antioxidant enzymes; Superoxide dismutase (SOD), Glutathione-S transferase (GST) and Catalase (CAT). The methanolic leaves extract of the E.macroclada was separated with ethyl acetate, n-hexane with a volume ratio of 1:10 into four fractions by using Column Chromatography (CC) technique. Folin-Ciocalteu’s and Aluminium chloride colorimetric method was used to analyse TPC and TFC, respectively while the antioxidant activities of column fractions were analysed by DPPH free radical scavenging assay. The inhibitory effects of E.macroclada extract were performed by testing the column fractions of extract on the activities of various antioxidant enzymes; SOD, GST, CAT. The results have shown that the TPC of the plant sample and its column fractions ranged from 43.61 to 7.26 mg/ g Gallic acid equivalent while TFC ranged from 37.05 to 2.93 mg/ g Quercetin equivalent. The DPPH IC50 values of column fractions of E.macroclada extract; FII, FIII and FIV were found to be 0.2541, 0.3409 and 3.42 g/l, respectively. The enzyme assays showed that the inhibitory effects of FII, FIII and FIV on GST enzyme activities were 92%, 98% and 78% respectively. Moreover, the inhibitory effects of both fraction; FII, FIII on CAT enzyme were about 99% while for FIV was just about 63%. Although all column fractions have strong inhibitory effects (especially FII, FIII) on GST and CAT enzyme activity, no inhibitory effects were observed on SOD.thesis.listelement.badge BIOCHEMICAL ANALYSIS OF α- ADRENERGIC RECEPTOR INHIBITORS: DOXAZOSIN AND TERAZOSIN(2022-02-28) SALEM, AMANI.M.M.; İşgör, S. Belgin; İşgör, YaseminThe objective of the study is to predict the medical purposes of alpha-blocker drugs by evaluating their effects on antioxidant defense enzymes beside to their antihypertensive actions. In order to do that, firstly Doxazosin mesylate and Terazosin hydrochloride solubility and stability were performed using UV spectrum of drugs measured at maximum wavelength of 245nm. Secondly, the effects of these drugs on the activity of antioxidant enzymes were studied for the first time with isolated or commercially available enzyme targets. In this study, the antioxidant effects of alpha-blocker drugs were analyzed by measuring the changes on the activity of these enzymes; Glutathione S-Transferase (GST), Superoxide Dismutase (SOD), Catalase (CAT) and Glutathione Peroxidase (GPX) upon exposure to various concentrations of drugs. The results have shown that the stability of Doxazosin mesylate in phosphate buffer (pH 5.2) and Terazosin HCl in water, were not exceeding two days although it is stored at -20 C. The enzyme assays showed that the inhibitory effects of Terazosin around 90% for Catalase (CAT) with IC50 0.0002403g/L and 96% for Glutathione Peroxidase with IC50 0.00442g/L. However Terazosin have opposite behavior on Superoxide Dismutase (SOD) with 70% inhibitory effect and IC50 of 0.008941g/L. The enzyme assay results showed that Doxazosin has inhibitory effect on Glutathione Peroxidase (GPx) around 85% with IC50 0.01109g/L and around 98% on Superoxide Dismutase (SOD) with IC50 0.0002177g/L., however Doxazosin have no significant effect on Catalase (CAT) enzyme. The inhibitory effects of both drugs on Glutathione-S-Transferase (GST) enzyme activity were less than 20%.thesis.listelement.badge COMPARATIVE STUDIES FOR SYNTHESIS OF ALGINATE MICROSPHERES AND NANOSPHERES AS DRUG CARRIERS(2022-02-24) ALZAWI, HANA M. HAMAD; İşgör, S. Belgin; İşgör, YaseminThe aim of the study is to compare the methods for synthesis of alginate microspheres and nanospheres and get the best size and spherical shape of alginate particles which are used in future as drug delivery. Four groups of methods were done for this purpose, each group of methods was followed the same protocol with some changes. The six methods of the first group were compared between two types of surfactants and also the ratio between alginate and surfactant was compared too. Furthermore, the seven methods of second group were compared in period of stirring time and concentration of alginate, surfactant and crosslinkers. In the third group of study, there are four methods comparing the use of alginate medium viscosity instead of low viscosity and trying to use different type and concentration of crosslinkers (CaCl2 46%, CaCl2 60%, MnCl2 60%, ZnCl2 60%). The final group of our study contains six methods comparing two types of poly vinyl alcohol (low molecular weight and high molecular weight) and different types of crosslinkers (CaCl2 60%, MnCl2 60%, ZnCl2 60%). From the twenty three methods were done in our laboratory, the best SEM result was the first method of the fourth group with 5µm in diameter of alginate microspheres that were prepared when using the alginate 1% (low viscosity) with PVA 2% (low molecular weight), AOT 5% and calcium chloride 60%.thesis.listelement.badge DESIGN AND OPTIMIZATION OF AN ATMOSPHERIC DISTILLATION UNIT IN AN OIL REFINERY(2017-05-02) SOWANI, KHALED; Kayı, Hakan; Alper, ErdoğanToday, production and distillation of crude oil are important processes in almost all around the world. Price of the petroleum products is rising due to the high demand which is much stronger than expected. In the last few years, simulation of the different processes has become an important tool, especially in the study of behavior of almost all the chemical processes. A proper simulation can bring the best advantages to industry, such as improving the in knowledge about the processes without the need to carry out the real operation of the processes. Simply, simulation can translate the mathematics of a computer modeling to description of the system behavior based on the data of input parameters. Simulation and modeling are very important in different engineering applications, because they describe the process operation that may not be feasible, may be inaccessible, too costly, or dangerous. In this study a computer model of atmospheric distillation unit (which is also called crude distillation unit, CDU) in Libyan oil refinery was designed and simulations were performed to improve the middle distillate productions in CDU focusing on Naphtha product. Data of the crude oil, the operating conditions of the process unit, and other essential data were collected from actual refinery and entered into the simulation environment to generate the CDU model. Aspen program provides a capability to design the entire process accurately and gives us accurate information of how processes take place. This study includes the design and simulation of the crude distillation unit, and aims to improve its middle distillate productions, by concentrating on the improvement of the volumetric flow rate of the naphtha product, because it’s one of the most demanded valuable products. According to our findings, it’s possible to increase mainly the production of naphtha, kerosene (jet fuel), light gas oil (LGO). In addition reducing the residue volumetric flow rate at the same time is possible, and this is one of the objectives of this study. Ultimately, the simulation of the CDU is successfully completed, and the obtained results are discussed. The effects of the different operation conditions in the crude oil refining process on the yield and the composition of the crude oil products are investigated. To ensure the simulation works successful, the obtained results are compared with the actual distillation column production data.Item DESIGN OF NOVEL PLATINUM AND PALLADIUM COMPLEXES CONTAINING PYRIDYL TYPE LIGANDS FOR CANCER TUMOR TREATMENT USING MOLECULAR MODELING APPROACH(2022-02-21) EL-HA, RABIA; KAYI, Hakan; ÖZALP YAMAN, ŞenizIn the middle of the last century, after the discovery of a compound of cisplatin, this compound became one of the most important chemical compounds used in the treatment of several different types of cancer. But despite the ability of this compound to kill and destroy cancer cells, it is still unable to treat several types of cancer in addition to side effects caused by this compound, which led scientists to search for another compound is more effective and without side effects. Many of the drugs that have been discovered have shown little of their efficacy against cancer. Despite the techniques and progress we have achieved, and the countless number of doctors devoted to fight it, cancer remains a real threat, an incurable disease, but nevertheless, there is still hope. Scientists have come up with treatments that seemed impossible 50 years ago, and they managed to get rid of some cancers that were called incurable. We started using treatment tools in different ways to achieve great results. Although the cancer may still be terrifying and may always remain so the steps we have taken against it have made treatment not only possible, but within reach. Previous studies can conclude that platinum and palladium compounds are among the most effective compounds against cancer cells if we take in account many parameters such as suitable ligand, good geometry and active leaving group. From here, the research began to design and develop some platinum and palladium compounds as alternative cancer treatment compounds. In this research sixteen platinum and palladium compounds were designed with two different types of ligands. New compounds were designed and tested theoretically by using density functional theory, DFT. The geometry optimizations and spectroscopic properties of these complexes such as FTIR, NMR and UV-vis were calculated using the Gaussian program by using B3LYP/LANL2DZ level of theory. The process of interaction of these compounds with two types of DNA was then simulated using the Docking program which revealed that our complexes interacts with DNA through different mechanisms than that of cisplatin (covalent, electrostatic, groove and intercalation) which may lead to overcome the side effects of cisplatin. The theoretical results of the compounds are very encouraging. Some of these compounds have been experimentally tested on live cells and have proven effective against several types of cancer. The good agreement between the experimental and theoretical results was observed. The new complexes in question have promising results for further future studies on these complexes.thesis.listelement.badge DESIGN, SYNTHESIS AND BIOLOGICAL ACTIVITY OF NOVEL ANTITUMOR ACTIVE PLATINUM AND COPPER BASED COMPLEXES CONTAINING QUINOXALINE LIGANDS(2022-03-10) El- Beshti, Hager Sadek; ÖZALP YAMAN, Şeniz; chemistryAcross the globe, today, cancer accounts for many fatalities, thus calling for better and updated antineoplastic agents within biomedicine and health sciences. In this regard, inorganic chemistry for pharmaceutic purposes is essential in creating drugs based in metal to fight cancer as such medicine has been shown to be potentially effective to fight cancer in humans. In light of this background, this research focuses on synthesis and anticancer activity of (2,3-di-pyridin-2-yl-quinoxaline), (2,3-di-thenyl-2-yl quinoxaline), (2,3,2',3'-tetra-pyridin-2-yl-[6,6']biquinoxaline) and (2,3,2',3'-tetra thenyl-2-yl-[6,6']biquinoxaline) containing copper(II) and platinum(II) compounds as prodrug candidates. The binding interaction of these compounds with calf thymus DNA (CT-DNA) and human serum albumin (HSA) of the complexes were assessed with UV titration, thermal decomposition, viscometric, and fluorometric measurements. The nature of the binding of the complexes on DNA were revealed as electrostatic interaction between the cationic metal complex ions and the negative phosphate groups of CT DNA upon removal of one or two labile chloride ion(s), except Pt(tpbq)Cl2, Pt(ttbq)Cl2, and Cu(tpbq)Cl2; van der Waals and hydrogen bonds interaction were proposed for these complexes. In addition, our complexes induced a surface contact through the hygroscopic region of serum albumin. Antitumor activity of the complexes against human glioblastoma A172, LN229, and U87 cell lines and human lung A549, human breast MDA-231, human cervix HeLa, and human prostate PC-3 cell lines were investigated by examining cell viability (MTT), oxidative stress, apoptosis-TUNEL, in vitro migration an invasion, in vitro Comet DNA demage, and plasmid DNA interaction assays. The U87 and HeLa cells were investigated as the cancer cells most sensitive to our complexes. The exerted cytotoxic effect of complexes was attributed to the formation of the reactive oxygen species in vitro. It is clearly demonstrated that Cu(dtq)2Cl2, Cu(ttbq)Cl2, Pt(ttbq)Cl2 and Pt(tpbq)Cl2 have the highest DNA degradation potential and anticancer effect among the tested complexes by leading apoptosis. Wound healing and invasion analysis results also supported the higher anticancer activity of those complexes.thesis.listelement.badge DESIGN, SYNTHESIS AND DNA BINDING ABILITY OF NOVEL PLATINUM(II) COMPLEXES CONTAINING BIDENTATE NITROGEN AND SULPHUR DONOR LIGAND(2017-01-07) ABDUSALAM, MOHAMED; ÖZALP YAMAN, ŞenizOne of the main challenges in bioinorganic chemistry is to synthesize new DNA targeting complexes as a potential anticancer drug leads providing better efficiency with low tissue resistance compared to cisplatin. For this purpose, three novel platinum(II) complexes containing 5,6-di-2-thienyl-2,3-dihydropyrazine in asymmetric- (asy-), cis and bis- geometry have been synthesized, identified and their DNA binding ability has been studied by spectroscopic techniques and gel electrophoresis. Spectroscopic data and the calculated binding constant values were demonstrated that the synthesized drugs bind DNA in different types. While Cis and Asy complexes perform base binding covalently, bis complex interact with DNA by intercalating mode but in weaker extend. Gel electrophoresis results were in agreement with the spectroscopic findings. All the complexes induce an oxidative single strand cleavage in the presence of a reductant (ascorbic acid) on the double helix structure of DNA with the decreasing activity order from Asy to Bis. On the other hand, cytotoxicity experiments carried out at the neutral conditions, suggested that the Bis complex is the most promising anticancer agent for the treatment of Human Glioblastoma.thesis.listelement.badge DETECTION OF BLOOD TRACES: SYNTHESIS AND CHARACTERIZATION OF A LUMINOL-TYPE COMPOUND(2022-06-13) KESİMAL, BÜŞRA; Cihaner, AtillaLuminol is a compound used in many fields, including analytical measurements mainly for forensic science. The synthesis of new luminol-type compounds has gained great importance due to the use of luminol in many fields and also having some disadvantages. In this thesis, a trimeric chemiluminescent 5,8-di(thiophen-2-yl)-2,3- dihydrophthalazine-1,4-dione (T2B-Lum) compound with pyridazine ring has been studied. After the synthesis and characterization, the chemiluminescence reactions of the compound was investigated in basic medium (0.1 M sodium hydroxide solution) with different oxidants (hydrogen peroxide, potassium permanganate, potassium dichromate). Afterwards, the optical property and chemiluminescence reaction of T2B-Lum with hydrogen peroxide in alkaline solution in the presence of various metal ionswere studied. T2B-Lum exhibits two absorption bands at 262 and 330 nm in dichloromethane and emits green light at 495 nm when excited. The quantum yield was calculated as 15.11% in dichloromethane when considering the luminol quantum yield is 100%. On the other hand, it was observed that some metal cations, especially copper(II) ions, catalyze the chemiluminescent reaction. It was also observed that the chemiluminescent emission was catalyzed by iron(III) ions. After this observation, the chemiluminescent behaviors of T2B-Lum with hydrogen peroxide in alkaline solution were studied in the presence of hemin and blood samples used as catalysts since these samples contain iron ions. Finally, the ion recognition property of T2B-Lum was investigated. Except for other metal cations (silver(I), cadmium(II), cobalt(II), iron(III), lithium(I), magnesium(II), manganese(II), nickel(II), zinc(II)), it has been observed that T2B-Lum is mostly sensitive to copper(II) ions with a detection limit value of 2.2×10-3 M.thesis.listelement.badge DETERMINATION OF PHOTOCATALYTIC DEGRADATION PRODUCTS OF DYE MOLECULES FOUNDED IN TEXTILE WASTEWATER(2017-06-02) AL-NASERI, Hiba Alaa Majeed; KAYA, MuratPhotocatalytic process is widely applied to remove hazardous organic compounds, microorganisms founded in water, volatile organic compounds and plastics waste by decomposing and destructing them founded in wastes. In this process, oxidation and reduction reactions occur on the surface of photocatalytic materials with the help of conduction band electrons and holes generated on valence band under ultraviolet (UV) or visible light radiation. Among the wastes mentioned above, textile based waste water is so important due to the highly toxic dye contents. Characterization of the degradation products of dye molecules obtained at the end of the process is so important in order to reveal the properties of them. Also characterization of the intermediates is so important to find the degradation pathways. Degradation products and intermediates can be followed by two different ways. In the first one the color of the solution is followed with UV-vis spectrometry. In the second way the final products can be founded with gas or liquid chromatography coupled with different types of detectors like flame ionization (FID), thermal conductivity (TCD) and mass (MS). This study is related to find the photocatalytic degradation products of dye molecules founded in textile wastewaters. For this, photocatalytic degradation products of methylene blue (MB) were investigated which are produced in the presence of TiO2 nanoparticles and palladium nanoparticles added PEDOT (PdNPs/PEDOT) under UV irradiation by using UV spectroscopy and liquid chromatography-mass spectrometry (LC-MS). The obtained results showed that the initial structure of MB was decomposed under UV light exposure in both the photocatalytic reactions in which TiO2 nanoparticles and palladium nanoparticles loaded PEDOT (PdNPs/PEDOT) were used. TiO2 nanoparticles are widely used in photocatalytic dye decomposition reactions and degradation products and pathway are given in literature. The results obtained in this study for the photocatalytic degradation of MB with TiO2 nanoparticles under UV light exposure are in consistent with the literature. In the case of PdNPs/PEDOT, new catalyst, the main degradation products are similar to those obtained with TiO2 nanoparticles. So, it can be concluded that photocatalytic degradation of MB by using PdNPs/PEDOT followed the same degradation pathway as TiO2 nanoparticles under UV light exposure. Besides this work provides a good insight into the decomposition products and pathway for the PdNPs/PEDOT assisted photocatalytic degradation of MB molecules under UV light irradiation.thesis.listelement.badge DEVELOPMENT OF HIGH PERFORMANCE BIMETALLIC CATALYSTS FOR PROTON EXCHANGE MEMBRANE FUEL CELL(2022-01-25) AL-Tememy, Mogdam Gassy Hussein; Devrim, YılserDespite the growing energy demand due to the growing population and lack of fossil fuels, which is a serious concern, there must be an alternative source where research focused on renewable energy sources. Proton Exchange Membrane Fuel Cell (PEMFC) is an important and alternative technology worldwide in automotive, portable and stationary applications due to their high-efficiency, zero-emission, lightweight, fast start-up and shut down properties. High Temperature PEMFC (HT PEMFC) eliminates some of the issues facing Low Temperature PEMFC (LT PEMFC) such as carbon monoxide (CO) poisoning, humidity, heat and water management. In this thesis, Multiwalled Carbon Nanotube Doped Graphene Nanoplatelet (MWCNT-GNP), MWCNT and GNP have been used as catalyst supports for the Pt:Pd bimetallic catalysts of the HT-PEMFC. The study of the dispersion of the catalyst nanoparticles on the different supports was achieved by using microwave assisted synthesis. The morphology, chemical structure and the percentage metal ratio of catalysts were characterized by using X‐ray diffraction (XRD), Thermogravimetric Analysis (TGA), Transmission Electron Microscopy (TEM) and Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS). TGA has confirmed the improved thermal stability of catalysts. TEM was demonstrated dispersion and uniform distribution of the catalysts. The Electrochemical Surface Area (ECSA) of the catalysts was determined by using Cyclic Voltammetry (CV) method. ECSA of Pt:Pd/MWCNT-GNP catalyst and Pt:Pd/GNP and Pt:Pd/MWCNT catalysts were calculated as 43.8 m 2 /g, 53.5 m 2 /g and 71.7 m 2 /g, respectively. The lowest ECSA loss was determined at 48 % in Pt:Pd/MWCNT-GNP catalyst. The results indicated that better deposition, uniform distribution and higher electrochemical surface area of the Pt:Pd/MWCNT-GNP catalyst compared to the other catalysts. The performance of the bimetallic catalyst has been confirmed on the HT-PEMFC performance test based with the pure H2/air and reformate gas/air experiment at 160°C. Results of experimental performance test showed the current density at 0.6 V is 0.3 A/cm 2 and 0.24 A/cm2 with pure H2/air and reformate gas/air, respectively for Pt:Pd/MWCNT-GNP catalyst. If HT-PEMFC performance results are compared, it is determined that the best performing catalyst is Pt:Pd/MWCNT-GNP catalyst.thesis.listelement.badge DNA INTERACTION AND CYTOTOXICITY OF THE PLATINUM BLUE COMPLEX CONTAINING 2-AMINOTHIOPHENOL(2017-01-07) SALEM, SAFIA; ÖZALP YAMAN, ŞenizSince the discovery of cisplatin, metal based agents have gained significant interest of researchers as potential anticancer drugs. Several drugs have been rationally synthesized to overcome the hurdles of cisplatin, majorly its toxicity and resistance. Search for less toxic, but still potent anti-cancer platinum compounds revealed a class of platinum complexes with pyrimidines called platinum-pyrimidine complexes also known as “platinum blue” (Pt-blue) complexes. Here, we describe DNA binding ability of the Pt-blue complex [Pt4(2-atp)8(H2O)(OH)] (2-atp: 2- aminothiophenol). In order to investigate the nature of the interaction between the Pt-blue complex and DNA, spectroscopic measurements were made and the results of UV titration, thermal behavior, viscosity and fluorometric titration of the Pt-blue treated DNA were evaluated. Our results suggested that the compound was able to partially intercalate DNA that related to the anticancer activities of the drugs.thesis.listelement.badge FLAME AEROSOL SYNTHESIS AND CHARACTERIZATION OF PURE AND COPPER DOPED TITANIUM DIOXIDE(2022-01-20) Salman, Waqed Khudayer Salman; Ekinci Machin, NesrinRecently, applications of doped titanium dioxide nanoparticles are getting lot of attention from researchers. Especially nano-sized structures have found their way in the most promising research fields such as energy storage and production, carbon dioxide photo-reduction, pigments manufacturing, and water purification. Biggest interest is due to the enhanced characteristics of titania with better photocatalytic activity when it is doped. Flame Spray Pyrolysis (FSP) is one of the manufacturing methods in the production of nano TiO2, which is applied in this thesis. Operating parameters affect the morphology, crystallinity, optical properties, and the crystal phase of TiO2 in FSP production. TiO2, and 5 and 10 % copper doped TiO2 (Cu/TiO2) have been manufactured in a short residence time to avoid sintering. The products were characterized by X-ray diffraction (XRD), N2 adsorption-desorption analysis (BET), scanning electron microscopy (SEM), transmission and high resolution electron microscopy (TEM/HRTEM) analysis, and ultra violet- visible- diffuse reflectance spectroscopy (UV-vis- DRS), in order to understand their characteristics such as crystallinity, morphology, particle size distribution, surface area, crystal phase content and optical properties. Characterization results of pure and Cu doped TiO2 showed that, fine nanoparticles had been manufactured with a high surface area that increased with adding more copper. Rutile phase was found to be the dominating crystal phase. It has also been found that adding copper to TiO2 increased the band gap for the manufactured products in this work. The band gaps energy values for TiO2, 5 % Cu/TiO2 and 10 % Cu/TiO2 were found as 3.59, 3.79 and 3.85 eV respectively.thesis.listelement.badge IMPROVEMENT OF MECHANICAL AND PHYSICAL PROPERTIES OF POLYURETHANE ELASTOMER/JUTE FIBER ECO-COMPOSITES BY APPLYING PROPER TREATMENTS TO FIBER SURFACES(2017-07-02) Salem, Tuffaha Fathe Salem; TİRKEŞ, Seha; TAYFUN, ÜmitIn this study, chopped jute fiber (JF) samples were surface treated by alkaline (Na), silane(Si) and eco-grade epoxy resin(EP). Surface characteristics of jute fibers were examined by FTIR and EDX analysis. JF filled polyurethane elastomer (TPU) composites were prepared via melt compounding. The effect of surface modifications of JF on mechanical, damping, melt-flow and morphological properties of TPU based eco-composites were investigated by performing tensile and Shore hardness tests, dynamic mechanical analysis (DMA), melt flow index (MFI) test and scanning electron microscopy (SEM) techniques, respectively. Mechanical test results showed that silane and epoxy treated JF improved the tensile strength and tensile modulus of unfilled TPU. Elongation at break of TPU decreased drastically with all kind of JF inclusions. All of the surface treatments resulted increase in hardness value of TPU. Similarly with mechanical test results, Si-JF and EP-JF containing composites showed enhancement on storage modulus. Glass transition temperature (Tg) of TPU rised up to higher temperatures after JF additions. Inclusions of JF caused increase for MFI value of neat TPU. Silane and epoxy treated JFs displayed homogeneous dispersion into TPU and their surface were covered by polymer phase according to SEM microphotographs.thesis.listelement.badge INFLUENCE OF BORON NITRIDE ADDITION ON THE PERFORMANCE OF HIGH TEMPERATURE PEM FUEL CELL BASED ON POLYBENZIMIDAZOLE MEMBRANE(2022-01-14) Hussin, Dedar Emad; Devrim, YılserWith the growth of the world population in the last decades, the energy demand has also increased due to technological developments and requirements. In this context, Proton exchange membrane fuel cell (PEMFC) has been gaining attention as an alternative to produce renewable energy lately thanks to its high efficiency, low pollution, high power density, and quiet operation. However, there must exist a high level of CO tolerance to be able to commercialize this alternative along with the use of reformed gasses produced from short processes, namely natural gas and methane – in abundant use today. High-temperature proton exchange membrane fuel cell (HT-PEMFC) allows for smooth water management and increased carbon monoxide (CO) tolerance to over 100 ℃ of operating temperature. Against this backdrop, the present thesis is an attempt to design novel Polybenzimidazole/Boron Nitride (PBI/BN) composite membranes for HT-PEMFC application. BN was preferred due to its acceptable thermal stability, low electrical conductivity and high plasticizer property. This filler is used as 2.5, 5, 7.5 and 10 wt. %. The composite membranes are tested using thermogravimetric analysis (TGA), Scanning Electron Microscopy (SEM), mechanical analyses, acid doping/leaching, and proton conductivity measurements. Accordingly, thermal gravimetric analysis confirm the thermal stability of the PBI composite membranes; whereas acid leaching proves that adding more inorganic BN particles reduces acid loss from the membrane signifi- cantly. Proton conductivity measurements show that introducing BN in the polymer matrix increases such conductivity, up to 0.260 S/cm at 180oC for PBI/BN-2.5 The HT-PEMFC performance test for PBI-BN-2.5 membrane is carried out in comparison with the PBI membrane, with results revealing that the former achieves higher performance with a current density of 136 mA/cm 2 at 0.6 V and 132 mW/cm 2 maximum power density at 165 oC. The high performance of this MEA can be attributed to elevated proton conductivity and the enhanced properties of the PBI-BN 2.5 membrane. Overall, the findings in the present thesis show the usability of PBI/BN composite membranes in HT-PEMFCs, and their applicability for commercial fuel cell production upon further improvements.thesis.listelement.badge INFLUENCE OF SURFACE TREATMENTS OF FELDSPAR AND QUARTZ MINERALS TO ELASTOMERIC POLYURETHANE BASED COMPOSITES(2022-06-20) BOUZMANE, Hajar; TİRKEŞ, Seha; TAYFUN, ÜmitIn this thesis study, surface treatment routes including silane modifications were applied to quartz and feldspar minerals (purchased from Eczacıbaşı Esan, Istanbul, Türkiye) to achieve a compatible mineral surface with the polymer matrix. Surface characteristics of minerals were examined using chemical analysis and surface functionality by Fourier transformed infrared spectroscopy (FTIR) method. Thermoplastic polyurethane-TPU (supplied by Ravago Petrochemicals, Izmir, Türkiye) was compounded with pristine and modified minerals by melt-blending technique. TPU-based composites were fabricated at a constant adding amount of 10% by weight for each additive. The dogbone-shaped test samples were prepared using an injection molding process. Mechanical, thermo-mechanical, melt-flow, and morphological characterizations of TPU and composites were performed by tensile and Shore hardness tests, dynamic mechanical analysis (DMA), melt flow index (MFI) measurements, and scanning electron microscopy (SEM), respectively. Effects of surface treatments were discussed comparing the findings of composites filled with pristine and modified minerals with the help of test data.thesis.listelement.badge INVESTIGATION OF HYDROGEN PRODUCTION FROM SODIUM BOROHYDRIDE HYDROLYSIS WITH SUPPORTED METAL CATALYST(2022-01-14) Al-Msrhad, Tuqa Majeed Hameed; Devrim, YılserIn recent years, the decrease in fossil fuel resources and the increase in environmental pollution has increased the interest in alternative energy sources. Among alternative energy sources, Hydrogen (H2) energy is of great importance due to its high energy density. The most important benefit in using H2 energy isthe clean and easy production and storage. When H2 production methods are examined, sodium borohydride (NaBH4) based H2 production is of great significance, and the particular reason for this circumstance is that it is renewable, reliable, and efficient and can easily be integrated into proton exchange membrane fuel cells (PEMFC). In this thesis, Palladium-Ruthenium (Pd:Ru) bimetallic catalyst supported on Multi walled Carbon Nanotubes (MWCNT) and Multiwall Carbon Nanotube Doped Gra phene Nanoplatelets (MWCNT-GNP) has been developed for H2 production from hy drolysis of NaBH4 for PEMFC application. These catalysts were synthesized by the microwave assisted synthesis approach. The prepared catalysts were characterized by Thermogravimetric Analysis (TGA), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and cyclic voltammetry analysis (CV). The electrochemical sur face area (ECSA) of the PdRu/MWCNT and PdRu/MWCNT-GNP catalysts were determined as 12.36 m2 /g and 20.74 m2 /g, respectively. PdRu/MWCNT showed a faintly lower ECSA loss as 34%. iv The catalysts were tested to investigate the H2 production from the chemical hydrolysis of NaBH4. Hydrolysis reactions were examined under various experimental condi tions. Kinetic studies were executed for PdRu/MWCNT and PdRu/MWCNT-GNP, and the activation energies were found as 18.90 kJ/mol and 22.33 kJ/mol, respectively. The reusability experiments with PdRu/MWCNT-GNP revealed that GDL supported catalysts maintained its 89 % efficiency better than the powder catalyst. The PEMFC test performed at 65oC showed that the H2 generation system based on solid NaBH4 hydrolysis and pure H2 have similar performance. The obtained results showed that the PdRu/MWCNT-GNP bimetallic catalyst is an appropriate catalyst to produce H2 from hydrolysis of NaBH4 for PEMFC application.thesis.listelement.badge INVESTIGATION OF THE ANTIBACTERIAL ACTIVITY OF SILVER NANOPARTICLES ADDED POLY (N- METHYL ANILINE)(2022-02-16) ALDARAJI, MOSTAFA KAMIL MAALA; İŞGÖR, Sultan Belgin; KAYA, MuratHumans, animals, and crops may suffer from many diseases that are caused by certain types of bacteria. These bacteria need to be deeply researched to identify the optimal means through which these can be faced. Among these types of bacteria are (Escherichia coli) and (Staphylococcus aureus). Silver is one of the most important mineral elements used in the treatment of the spread of these bacteria, as it has some chemical and physical properties that can eliminate bacteria. One of these properties whose activity has been examined is Nanotechnology. Which are particles ranging in size from 1 to 100 nanometers. It has been found that these particles can penetrate the outer membranes and enter the cell. By using so, it works to stop the production of protein and starts to kill the living cell due to the high toxicity found with silver nanoparticles. In addition, poly (n-methyl aniline) was added to the silver nanoparticles. PNMA was prepared with 0.025 M monomer solution. The size of the resulting PNMA spheres lies between 200-550 nm. The oxidative chemical polymerization and liquid impregnation methods were used to successfully prepare poly (N-methyl aniline) silver nanoparticles (PNMA-AgNPs). SEM, TEM, EDX, and ICP-OES were used to characterize the resulting particles. It has been studied the antibacterial effect of these compounds; PNMA and Ag-PNMA against the Escherichia coli and Staphylococcus aureus and compare the effect of these compounds with penicillin/streptomycin common antibiotic.thesis.listelement.badge INVESTIGATION OF THE PHOTOCATALYTIC ACTIVITY OF PALLADIUM NANOPARTICLES ADDED PEDOT(2017-01-07) AHMED, Matira Miud Alaribi; KAYA, MuratInvestigation and development of efficient and low-cost method for wastewater treatment to effectively eliminate the pollutants is so important for environmental remediation. Among the wastewater treatment methods, advanced oxidation processes (AOP’s) consists of the usage of homogenous and heterogeneous photocatalysts, known as the most effective way. The development of photocatalytic materials used in AOP’s is so important. The advancement of photocatalysts which sensitive to solar light would allow more effective utilization of solar light brings sustainable ways to various environmental problems. Recently conductive polymers noted as a new types of effective photocatalytic materials under solar light. Poly(3,4-ethylenedioxythiophene) (PEDOT) considered as one of the most important candidate among the conjugated polymers. In this thesis, photocatalytic activity of the palladium added PEDOT (PdNPs/PEDOT) polymer was investigated. In this study, a facile production procedure was demonstrated to fabricate the PdNPs/PEDOT as a photocatalyst. The phtocatalytic activity of PdNPs/PEDOT nanocomposite material was checked into the decolorization of MB under UV and solar light exposure. The photocatalytic behavior of bare PEDOT, TiO2 nanoparticles and PdNPs/TiO2 nanostructure were also investigated in order to make comparison with PdNPs/PEDOT nanostructure. The characterization of nanocomposite catalysts were done by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM) energy dispersive X-Ray (EDX) coupled with SEM and Raman Spectroscopy.