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  • Küçük Resim
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    Conductance and Density of Interface State Characteristics of Mn Doped CdO Photodiodes
    (2020) Koç, Mümin Mehmet
    Sol-gel technique was used to fabricate cadmium oxide and manganese doped cadmium oxide solutions whichwere used to produce thin films. 10% manganese doped, %6 manganese doped, %0.2 manganese doped andundoped cadmium oxide solutions were spin-coated on Si wafers to fabricate photodiodes. Conductance –voltage (G - V) measurements were performed. Mn doping enhances the conductance properties of the CdOdiodes. Increased conductance characteristics were obtained with increasing AC signal frequency. Correctiveconductance – voltage (Gadj – V) graphs were obtained using conductance voltage graphs. Increased correctiveconductance (Gadj) values were obtained with increasing AC signal frequency. Using corrective conductance –voltage (Gadj – V) and conductance – voltage (G - V) data density of interface states (Dit) characteristics of thediodes were assessed. Different density of state values was obtained for the different photodiodes. The densityof state values was found to increase with increased Mn doping.
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    Magnetic dendrimer-encapsulated metal nanoparticles (Au, Ag): effect of dendrimerization on catalytic reduction of 4-nitrophenol
    (Springer, 2022) Yetim, Nurdan Kurnaz; Koç, Mümin Mehmet; Nartop, Dilek
    Magnetic nanoparticles (MNPs) and nanocomposites can be used in different applications including catalysis reactions and applications. Magnetic nanocomposites can be reused and magnetically filtrated after catalysis reaction. For this purpose, Fe3O4 MNPs were produced using the co-precipitation technique. Fe3O4 MNPs were coated with SiO2 shell, APTES and G2 PAMAM dendrimers and lastly doped with Au and Ag nanoparticles (Fe3O4@G2/Au/Ag) which has been examined for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4 as a model reaction. Physical structures of the nanocomposites were characterized using SEM and TEM which illustrate that nanoparticles were in composite form. Chemical composition of nanostructures was confirmed using EDX and FTIR. Magnetic characteristics were checked using VSM. Dendrimerization and Au and Ag nanoparticle doping on catalytic and magnetic properties were deeply assessed. PAMAM dendrimer coating on Fe3O4 nanoparticles results in a slightly decreased magnetic saturation value and in the reaction rate of 4-NP reduction. Au and Ag embedding in PAMAM dendrimers slightly increases the reaction rate while reducing the overall magnetic saturation values of nanocomposites. [GRAPHICS] .
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    Optimization of KI as X-Ray Computed Microtomography Contrast Agents for Murine and Chicken Epidermal Tissues Applications
    (2020) Koç, Mümin Mehmet
    X-ray computed tomography (CT) is vastly used in many different applications in different fields such asmaterials science, medical science, entomology, anatomy, marine sciences. Since the X-ray is highly penetrable,3D image of almost any material can be achieved by CT. The high quality image of the materials, which arecomposed of different types of atoms, can easily be achieved. However, obtaining the high quality images of thematerials which has similar types of atoms or relatively soft structure becomes problem. Scientist investigatingthe soft tissues such as flesh, muscle, cartilage or animals in soft structure suffer from this problem. At this point,staining procedure, treating materials with contrast agents help researcher to enhance the image quality. In thiswork, optimization of KI based staining to obtain enhanced image quality in CT imaging of murine and chickendermal tissues were studied. Results indicate that overstaining or staining the tissues in less concentrationsignificantly affects the quality of the obtained CT images.