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In this study, sodium alginate/poly (vinyl alcohol)/clinoptilolite composite membrane was obtained for the separation of dimethylformamide/water mixture by pervaporation method. Cross-linked membranes were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and scanning electron microscope (SEM) instruments. Although the flux value (3.266 kg/m2 h) was found to be high, the desired result for selectivity could not be achieved. The activation energy for the 20% by weight DMF solution was measured as 3,720 kcal/mol. The effect of zeolite addition on membrane performance was investigated. [ABSTRACT FROM AUTHOR]

In this study, the effect of gas cementation, tempering and deep cryogenic treatment with different holding times (24, 36, 48 hours at -196 °C) on the corrosion behavior of cementation steel in 3,5% NaCl environment was investigated. The corrosion tests of the samples classified in five different groups were examined with the Electrochemical Impedance Spectroscopy (EIS) method, the degradation of the metal surface was visually investigated with the Scanning Electron Microscope (SEM), and the chemical composition of the surface was determined by Energy Dispersive X-ray Spectroscopy (EDS). The findings show that cementation, tempering and cryogenic treatment applications reduce the corrosion rate of cementation steel. It has been demonstrated by electrochemical and surface imaging methods that the N3 sample, which applied deep cryogenic treatment with 24 hours holding time after cementation, is much less corroded in 3,5% NaCl environment than other samples. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study is to evaluate the bond strength of different repair systems by using composite resin and ceramic cementation repair methods to zirconia-based ceramics. Material and Method: All-ceramic blocks (IPS Empress II; Ivoclar Vivadent, Schaan, Liechtenstein) sized 4.00 mm in length, 5.4 mm in width, and 3.00 mm in height were fabricated by dental laboratory as thirty specimens. CAD/CAM zirconia blocks (n =40) (Prozir; SeramDent, Turkey) sized 5.00 mm in length, 5.4 mm in width and 13.0 mm in height by CEREC System were fabricated from fully sintered Y-TZP core. Zirconia specimens were randomly divided into seven groups for the following different intraoral repair systems(Clearfil, Cimara Zircon, Bisco) and a control group. Every ten specimens were repaired as same sized. Control group was fabricated by conventional firing as unbroken solid zirconia ceramic samples. Each specimen underwent 5000 cycles of thermocycling. The SBSt (Shear bond strength test) was performed by loading force on the repaired piece to record load-to-failure. Failure mode was evaluated using a digital microscope and SEM. SBSt data were analyzed using one-way ANOVA and Tukey’s HSD test. Results: Clearfil and Cimara Zircon systems significantly increased the bond strength for composite resin method when compared with the Bisco system (respectively p <0.001, p =0.001). All-ceramic method significantly increased the bond strength when compared with the composite resin in Bisco system (p <0.001). Conclusion: Although the composite restoration method is effective for repair, the all-ceramic/zirconia repair method can be an option for repairing layered zirconia restorations. [ABSTRACT FROM AUTHOR]

In this study, the CuO thin films were deposited on glass substrates at different substrate temperatures (350, 400, 450, and 500 C) by the ultrasonic spray pyrolysis (USP) method and then annealed at 525 C. In X-ray diffraction (XRD) analysis, the peak intensity was not found in thin films at 350 C substrate temperature and as-grown conditions. Two distinct peaks were observed at 36 and 39 in the XRD patterns of other films. These peaks are characteristic peaks of the monoclinic crystal structure of CuO. Atomic force microscopy (AFM) and scanning electron microscope (SEM) images of the produced thin films were examined. The surfaces of thin films are not smooth. After annealing, grain agglomerations were formed. The optical properties of the CuO thin films were analyzed by ultraviolet-visible region (UV-Vis) measurements. Forbidden band gap values (Eg) were calculated from Tauc graphs for as-grown and annealed samples. It has been observed that the structural, morphological, and optical properties of CuO thin films produced by the USP method can be controlled by the substrate temperature. [ABSTRACT FROM AUTHOR]

In this study, it is aimed to produce nanofibers via electrospinning method using a polymer solution doped with β-arbutin, which is known as an agent reducing skin blemishes. For this purpose, β-arbutin was added to the polyamide 6/formic acid solution with chosen concentrations as 2%, 5%, and 10% (w/v). After preliminary electrospinning process, scanning electron microscope (SEM) analysis was performed to determine the optimum spinning parameters. The SEM images presented that nanofibers with uniform morphology were obtained with the 2% (w/v) β-arbutin concentration. Three different voltages were applied for 2% (w/v) β-arbutin added solution and the best morphology was obtained by 30 kV voltages. According to the statistical analysis performed, it was seen that the mean diameters of nanofibers varied due to the β-arbutin concentration. In this study, it has been demonstrated that the thin and light nanofiber textile surfaces containing skin blemishes reducing agent can be produced via electrospinning method to be used as a cosmetic textile product. [ABSTRACT FROM AUTHOR]

Magnetite (Fe3O4), Humic Acid (HA) and Silver (Ag) are materials with important properties. Synthesizing a single material which will have all the properties of these materials can provide significant advantages for some application areas. In this study, synthesized Fe3O4@HA@Ag was doped into poly(vinyl pyrrolidone) (PVP), in weight ratios of 5%, 7.5% and 10%, and nanofiber production was carried out by electrospinning method. Structural properties of nanofiber structures were investigated by X-ray Diffraction (XRD), morphological properties by Scanning Electron Microscope (SEM), spectroscopic and thermal characterizations by Fourier transform infrared (FTIR) and Thermogravimetric Analysis (TGA). When the analysis results of nanofibers were evaluated, it was determined that Fe3O4@HA@Ag doped PVP nanofibers were successfully produced. [ABSTRACT FROM AUTHOR]

According to the subjects covered, oil painting canvas are one of the most important movable cultural heritage that provide information about the art, style, social life, belief and history of the period. In this study, it was aimed to clean the dirt due to various reasons on oil canvas by using biopolymeric hydrogels. Hydrogels have many advantages in that they don't contain toxic substances and can be prepared with a fast and easy technique. The dirt on the canvas paintings that are historical artifacts were cleaned without damaging the building with the hydrogels prepared. Hydrogel structure was prepared as a cleaning material with plentiful and readily available alginates and natural gums biopolymers. The canvases aged by chemical methods were contaminated with dust, ash and soot to test the cleaning processes. As a result of the application of the hydrogel materials used on polluted and aged canvases, the results were analyzed with different microscopic and spectroscopic methods. The characterization of the materials was carried out using analysis methods as optical microscope, Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectrophotometer (FT-IR). [ABSTRACT FROM AUTHOR]

This research covers investigation of mode-I fracture toughness of the recycled waste mussel shell particles reinforced epoxy composites. Vacuum assisted resin infusion molding (VARIM) method was applied to produce composites. The aim of the research is to use recycled waste shells to reduce production cost and to prevent environmental pollution. VARIM was applied to produce fiber reinforced composite. Therefore, as reinforcement particles mussel shell, and as particle reinforced composite production method VARIM are both two new points of the research. Mode-I fracture toughness experiments conducted according to ASTM D 5045 standards with single-edge-notch bending specimens for six repeats. According to mode-I tests, the fracture toughness of the mussel shell particle reinforced epoxy composites is 2.44 MPa∙m1/2. The failure region from one of the tested specimen was investigated by scanning electron microscope (SEM) in the next section of the paper. After the test results are given by diagrams, they are discussed according to other particle-reinforced composites to show the new material place in the literature by means of fracture toughness. [ABSTRACT FROM AUTHOR]

In this study, CH3NH3PbI3-xClx perovskite thin films were deposited on glass substrates by the ultrasonic spray pyrolysis method. The effect of substrate temperature on the structural, morphological and optical properties of perovskite films was investigated using an Xray diffraction (XRD) device, scanning electron microscope (SEM), atomic force microscope (AFM), and Uv-Vis spectrophotometer. When the X-ray diffraction spectra were observed, it was determined that all films were formed in the tetragonal perovskite lattice structure, but it was observed that different undesirable crystal structures were formed in thin films with 75 °C and 100 °C substrate temperatures. Although no post-annealing process was applied to the films, it was determined that the films coated at 125 ° C substrate temperature were in the form of perovskite that has CH3NH3PbI3-xClx structure, which are exactly compatible with the literature. The crystal sizes of thin films were determined by using XRD spectrum data and Debye-Scherrer formula. The highest crystal size was obtained as 743 Å for the thin film deposited at a substrate temperature of 125 °C. When the SEM images were examined, it was determined that the film surfaces were homogeneously coated at only 125 °C substrate temperature and that there were very little voids between the crystal particles. The surface roughness of the films was examined by atomic force microscopy system, and the smoothest surface roughness was obtained in the thin film deposited at 125 °C substrate temperature with 41.32 nm. Optical absorption studies were carried out by using a Uv-Vis spectrophotometer operated at room temperature. It was observed that as the substrate temperature applied while coating the films increased, the forbidden bandgap of the film increased from 1.20 eV to 1.56 eV, which is also compatible with the theoretical analysis. [ABSTRACT FROM AUTHOR]

In this study, a new route was proposed for electrochemical synthesizing of TiO2 doped diamond-like carbon (DLC) nanocomposite film. To obtain TiO2 doped DLC nanocomposite film, firstly, titanium metal was dissolved in hydrogen peroxide (H2O2). Then, the obtained solution and methanol were mixed with the volume ratio of 1:200 and electrolyzed in a two-electrode cell. The obtained film was characterized by scanning electron microscope (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. SEM image showed homogeneous and porous film. Raman spectroscopy indicated that TiO2 doping leads to sp3 hybridized carbon bonds. XPS analysis confirm TiO2 doping and sp3 bonds. In the XRD spectrum, the observed peaks attributed to hexagonal carbon structure. The obtained results show that DLC nanocomposite film containing high amounts of sp3 bonds can be successfully produced by the electrochemical method. [ABSTRACT FROM AUTHOR]

Pisolithus arrhizus (Scop.) Rauschert (Basidiomycetes) type is an ectomycorrhizal fungi found in the soil that surrounds many species of eucalyptus and pine trees. In this study, it was aimed to determine the inhibitory effect of Titanium (TiO2) nanoparticle (NP) prepared by using Pisolithus arrhizus ethanol extract on different pathogenic microorganisms. In the study, NP's synthesized using hydrothermal method was characterized by UV-vis spectrometer (UV-vis) and scanning electron microscope (SEM). The antimicrobial activity of these prepared and characterized NP's, have been investigated by using disk diffusion method on test pathogens of Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Candida albicans and Streptococcus mutans. While NPs have a weak inhibitory effect on pathogens (7.5-9.3 mm), the maximum inhibition (9.3 mm) is shown against S. mutans. Whereas antifungal effect against C. albicans have not been found. [ABSTRACT FROM AUTHOR]

Purpose: In this study, it was aimed to immobilize urease from Canavalia ensiformis onto modified Florisil (magnesium silicate) by covalently and to characterize immobilized urease and also to investigate reusability of immobilized urease in a batch type bioreactor.Materials and Methods: Florisil was activated with 3-aminopropyltriethoxysilane and then modified with glutaraldehyde. Urease was covalently immobilized onto modified support. Images of support and immobilized urease were examined on a scanning electron microscope. The optimum pH and temperature, kinetic parameters (Km, Vmax, kcat/Km) and storage stabilities at 4°C and room temperature of free and immobilized ureases were determined. Reusability of immobilized urease was investigated in a batch type bioreactor.Results: Free and immobilized ureases showed their maximum activities at pHs 7.0 and 6.5, and at temperatures 50 and 60°C, respectively. The Km value of immobilized urease increased 2.2 fold compared to free urease. The catalytic efficiency of immobilized urease was about 0.1% of the free urease. Free urease completely lost its activity at the end of 5 days stored at 4°C and room temperature; however, immobilized urease did not lose its activity at the end of 19 days at the same conditions. Immobilized urease maintained 50% of its initial activity at the end of 10 reuses in batch type bioreactor.Conclusion: Although urease activity significantly decreased upon covalent immobilization onto modified Florisil. However, high storage stability and reusability of immobilized urease makes it potentially useful immobilized form. [ABSTRACT FROM AUTHOR]

Undoped and Erbium (Er) doped zinc oxide (ZnO) films were prepared on p-Si substrates by sol gel method using spin coating technique. The effect of Er dopant on the structural, morphological and optical properties of ZnO film was investigated by X-ray diffractometer, scanning electron microscope (SEM) and UV-vis spectrophotometer, respectively. From X-ray diffraction (XRD) spectra, the films were crystallized in hexagonal wurtzite structure in zincite phase. The structural parameters such as grain size, dislocation density, lattice parameters, strain and stress were calculated. From the SEM images, it is seen that the film surfaces are well-coated, uniform, without cracks and pores. ImageJ program was used to investigate the average particle size, grain boundaries and the surface of the films. The optical properties were studied by diffuse reflectance spectra measured by UV-vis spectrophotometer and the optical band gap values were determined by differential reflectance and Kubelka-Munk theory. In both methods, it was determined the optical band gap value of ZnO film increases or decreases irregularly with the Er content. It was observed that the optical band gap of the 0.4% Er doped ZnO film was larger than the other films. [ABSTRACT FROM AUTHOR]

In this study, the effect on the efficiency of CdS/CdTe solar cell with MoO3 buffer layer was examined. Two sample was grown as Cam/FTO/SnO2/CdS/CdTe/Au and Cam/FTO/SnO2/CdS/CdTe/MoO3/Au. MoO3 layer was deposited as a buffer layer between CdTe and metal electrode in the back contact of CdTe solar cell. Solar cells were grown on glass/fluorine tin oxide substrate by Sputtering system. The morphological properties of CdS/CdTe solar cell structure with MoO3 buffer layer have been evaluated by means of scanning electron microscope (SEM) and atomic force microscopy (AFM) measurements. In addition, the cell device was fabricated to obtain electrical output parameters of both the traditional CdTe-based cell and CdTe cell with MoO3 buffer layer. The current‒voltage measurements were carried out at room temperature under both dark and air mass 1.5 global radiations. The energy conversion efficiency value has been obtained for traditional cell and the cell with MoO3 buffer layer as 8.93% and 10.31% 1 Sun, respectively. It was observed that the integration of MoO3 layer into CdTe-based solar cell increased cell efficiency by 15.45%. [ABSTRACT FROM AUTHOR]

Shortening the processing time and increasing the efficiency have been a need in machining at all times. In addition to continuous developments in materials of cutting tools provided by the search every passing day, coating the surfaces of the existing cutting tools has been evaluated as more economical and more efficient solution. Studies deal with coating of cutting tools was started in the 1970s and coated tools were recognized as an important development in machining. Titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), cubic boron nitride (CBN), chromium nitride (CrN) and aluminum oxide (Al2O3) are among the most widely used coating materials. Coating studies focused on especially high-speed steel and sintered carbide cutting tools as they have wide application area. In traditional coatings, are coated in the form of layers. As a result of occurring high temperatures during metal cutting, the different thermal expansions take place between the layers. Different expansions cause micro-cracks and this reduces the coating life. As a result of efforts to prevent the formation of these cracks, functional graded coatings (FGC) has been developed. In the study, high speed steel substrate material was coated as functionally graded with titanium carbonitride (TiCN) and titanium-boron carbonitride (TiBCN) coating materials. Coatings were made by magnetic sputtering method. Scanning electron microscope (SEM) images were taken and linear analyses, were realized for characterization of the coatings. [ABSTRACT FROM AUTHOR]