Nilhan Kayaman Apohan

Removal of Lead and Cadmium Ions from Aqueous Solutions Using Sulphur and Oxygen Donor Ligand Bearing Hydrogels

A new thiourea and urea functional monomers were synthesized. A series of hydrogels were prepared by photopolymerization. The hydrogels were used for the removal of Pb(II) and Cd(II) ions from aqueous solutions. The influence of the uptake conditions such as the pH, the time, and the initial feed concentration on the metal ion binding capacity of hydrogel was tested. The selectivity of the hydrogels towards the different metal ions was also tested. The adsorption isotherm models were applied. The limits of detection and quantification were calculated. The usability of the hydrogels for preconcentration studies were also investigated.

Chitosan-co-Hyaluronic acid porous cryogels and their application in tissue engineering

In this work, the usability of chitosan-co-hyaluronic acid cryogels as a tissue-engineering scaffold was investigated. Chitosan-co-hyaluronic acid cryogels were synthesized at subzero temperature. Cryogels which were composed of various compositions of chitosan and hyaluronic acid (0, 10, 20, 30 and 50wt% hyaluronic acid) was prepared. Morphological studies showed that the macroporous cryogels have been developed with 90-95% porosity. Particularly, the mechanical and biomaterial property of pure chitosan was improved by making copolymer with hyaluronic acid in different concentration. The MTT cell viability results demonstrated that the cryogels have no significant cytotoxicity effect on 3T3 fibroblast and SAOS-2 cells.

Multi-Walled Carbon Nanotube Reinforced Polyimide Composites

Polyimides have a wide range of uses such as aerospace industry fuel cell applications, optic and electronic materials industry due to their outstanding thermal, mechanical and chemical properties. In this study, it was aimed to prepare composite polyimide films with amine tethered multi-walled-carbon nanotube (MWCNT). Firstly, to produce amine functional groups onto the surface of MWNCTs, MWCNTs were reacted with H 2 SO 4 /HNO 3 , thionyl chloride and ethylenediamine, respectively. Then polyamicacid solution was prepared from BTDA and ODA. The functionalized carbon nanotube was added to the PAA solutions with a certain amounts (1%, 3%, 4%, 5% and 6%wt.) and followed by stepwise thermal imidization. The thermal stability of the composite polyimide films were enhanced with addition of modified-carbon nanotube since covalent interaction between polyimide based matrix and modified-carbon nanotube happened by imidization reaction. In addition, the mechanical properties of the films were improved.

Preparation and characterization of chitosan-co-hyaluronic acid cryogels

T use of hydroxyapatite-reinforced composite materials in the medical field has considerably increased in recent years because of the high biocompatibility and bioactive properties of this material, especially when it is used in bone replacement applications. It is imperative that new materials are thoroughly analyzed to ensure bio-functionality. This study describes the response of human peripheral blood mononuclear cells (PBMCs), separated from leukocyte packages obtained from healthy donors, in contact with a 90-10 weight % composite manufactured from an isophthalic polyester resin and reinforced with HAp and calcium triphosphate particles. The viability of PBCMs in the presence of this novel composite was evaluated every 24 hours for 5 days using commercial luminescent cell viability assay (Premix WST-1 Cell Proliferation Assay), positive and negative controls were used. PBMCs are part of the immune system and are usually stimulated by antigens and mitogens. Although the viability assessment demonstrated that HApreinforced resin does not have a cytotoxic effect on the PBMCs, the high cell proliferation values obtained via ELISA could be due to a mitogenic or antigenic effect of the composite. Because of the elevated cell proliferation, it was needed to confirm that the material was not acting as a mitogen. To do this, yellow tetrazolium MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay with the cell line 231 (breast cancer cells) was performed. The viability of this 231 cell line was not affected by the presence of the composite. Based on the results, a pro-inflammatory mediator production assessment should be performed.I recent years, highly porous polymer composites are attracting considerable interest due to their large surface area, high chemical resistance, permeability properties, and low densities. These materials have numerous applications such as catalysis, filtration, energy exchange, sensors, etc. For this reason, preparation of such materials with different processes is frequently in focus of research. In this study we report novel macroporous composites for heterogeneous photocatalysis applications. With this aim, Pickering-high internal phase emulsions (Pickering-HIPEs) have been used as templates to build hierarchical open porous polymer networks. HIPEs are concentrated emulsions consisting of a high ratio of internal or dispersed phase. In case of, either one or both phases of a HIPE contain monomers, polyHIPEs can be produced. HIPEs are usually stabilised by using relatively high amounts of emulsifying agents against coalescence. However, it is also possible to stabilise a HIPE with the use of nanoparticles. In this case, the resulting emulsion and the final material are classified as Pickering-HIPE and poly-Pickering-HIPE, respectively. Herein, poly-Pickering-HIPEs were prepared using poly(ethylene glycol-co-propylene glycol-co-ethylene glycol) surface modified TiO2 nanoparticles (TiNPs). For this purpose, TiNPs were synthesised via sol-gel method and the resulting nanoparticles were introduced into the continuous phase consisting of monomers. The structural properties of TiNPs were characterised by using FTIR and XRD. Morphological properties of the resulting poly-Pickering-HIPE composite, on the other hand, were characterized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Moreover, mechanical properties of the poly-Pickering-HIPE were measured by performing uniaxial compression experiment. The specific surface areas of the TiNPs and poly-Pickering-HIPE were determined from the adsorption/desorption isotherms and calculated by the Brunauer-Emmett-Teller (BET) equation.Aerospace gas turbine engines are now designed such that the heat resistant super alloys operate at temperature very close to their melting, so current strategies for performance improvement are centered on thermal barrier coatings. Lower thermal conductivities lead to temperature reductions at the substrate/bond coat interface which slows the rate of the thermally induced failure mechanisms. Alternatively, lower thermal conductivity TBC layers might allow designers to reduce the TBC thickness there by decreasing the significant centrifugal load that the mass of the TBC imposes on the rotating turbine engine components. One approach to improve TBC system is to optimize the pore morphologies to reduce the thermal conductivity while still retaining high in-plane compliance. The second approach to improve TBC system performance is to optimize the surface microstructure, surface densification, phase structures mechanical characteristic, chemical structure, and thermo-physical properties.S years, conjugated polymers have received attention as low cost materials in active layer light emitting diodes but low efficiency of these materials made it a problem which should be considered. Recently, metal nanoparticles are used in display device’s active layer to increase the efficiency of materials. Metal nanoparticles enhance coupling between the Localized Surface Plasmon Resonance (LSPR) and exaction in emitting material. In this work, we use SILVACO and MATLAB simulators to examine silver nanoparticles. With the control of Surface Plasmon (SP) and the emission wavelength we can find the best absorbance peak location which maximized photoluminescence (PL) intensity, depending on various Ag, Au and Al dot condition. These metal nanoparticles are used in Solar cells and Polymer LEDs for maximizing the coupling between the LSPR.Y doped Co nano ferrites, CoFe2-x O4, where x varies as 0.05, 0.1, 0.15 and 0.2 were successfully synthesized using solution combustion route. X-ray diffractogram confirm the Spinel structure fornation and neutron diffraction analysis reveals the magnetic structure. The magnetic parameters obtained from VSM, namely coercivity and residual magnetisation were discussed in the light of results obtained from structure analysis. The electrical resistivity measurements confirmed polaron conduction mechanism in these ferrites. The dielectric measurements, and the impedance analysis have shown interesting results and are explained using Koop’s theory. Some peculiar results pertaining to loss tangent are explained proposing new models.