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Öğe Abaca fiber as an efficient reinforcement for high mechanical performance in metakaolin-based geopolymers(Wiley, 2024) Trindade, Ana Carolina Constancio; Sood, Sai Shruti; Silva, Deyvid do Carmo; Ozer, Ali; Kriven, Waltraud M.This study introduces an innovative method for efficiently integrating abaca fibers into a potassium-based geopolymer (KGP) material. Geopolymers often suffer from brittleness, and composite designs have been explored as a solution to enhance their strength and ductility. While synthetic reinforcements are commonly employed due to their consistent properties, natural fibers offer a renewable and eco-friendly alternative. However, their widespread use has been hindered by complex and time-consuming treatments, resulting in variable morphologies that affect fiber-matrix adhesion. It is worth noting that previous research has primarily focused on alkali-activated and cementitious applications, leaving a knowledge gap in understanding its interactions with calcium-free, metakaolin-based geopolymers. Consequently, this study aimed to simplify the conversion of raw abaca into uniformly chopped filaments, facilitating their integration into KGPs at levels of up to 7 wt%. The mechanical evaluation revealed exceptional performance, with compressive strengths reaching up to 45 MPa. A thorough analysis confirmed robust, fiber-matrix adhesion and identified the presence of lignin and cellulose, significantly contributing to the fiber's strength. Flow table tests showcased their versatility, transitioning from high flowability (1 wt%) to complete shape retention (7 wt%). Furthermore, all variations exhibited great ductility, multiple cracking formation, and minimal variability in mechanical properties.Öğe Effect of Calcination on Microstructure Development and Properties of Hydroxyapatite Powders Extracted from Human and Bovine Bones(INDIAN CERAMIC SOC, 2019) Oksuz, Kerim Emre; Kilinc, Seyran; Ozer, AliThis study represents a comprehensive discussion of hydroxyapatite (HAp) formation from human and bovine bones. The phase formation and surface morphologies of prepared HAp powders were determined by XRD and SEM analyses, respectively. TEM was employed to understand the internal compositions with high magnifications and particle size. FT-IR characterizations provided information about molecular interactions and structures. In order to understand the effect of heat treatment at different temperatures and ultimately to get the desired morphology/particle size of the HAp powders derived from human and bovine, the powder samples were calcined at 700 degrees to 1100 degrees C with an interval of 100 degrees C. At 700 degrees C, the organic components were removed and finally, a carbonate apatite was obtained. The degree of crystallinity and crystallite size were noticed to increase progressively with calcination temperature. The overall results showed that the calcination temperature highly influenced the properties of HAp powders derived from human and bovine bone samples. As expected, higher temperatures led to more pure form of HAp with higher degree of crystallinity, larger crystallite size, and a less porous structure. Besides, the human bone structure, in contrary to the bovine bone, did not show temperature sensitivity by means of crystallite size increase.Öğe Investigation of Demodex Spp. prevalence among managers and workers of health hazard bearing and sanitary establishment(ELSEVIER TAIWAN, 2012) Ozer, Ali; Karaman, Ulku; Degerli, Serpil; Colak, Cemil; Karadan, Mesut; Karci, ErdalBackground/Purpose: Two Demodex species are known to live on people. Demodex folliculorum lives in the openings of hair follicles alone or in groups. D brevis lives in the depths of the sebaceous glands alone. There are different related on the epidemiology of Demodex species have been published. Method: In this study, taking into account that the parasite is transmitted through close contact from person to person, we aimed to evaluate the relation between the presence of Demodex spp with gender and age among the Health hazard bearing and sanitary establishment operators and workers who came for porter examination. Results: For this purpose, 862 male and 215 female patients with a total of 1077 volunteers from the face area of the standard superficial skin biopsy (SSSB) method and studied samples were taken. More than five mites in 1 cm(2) density was defined as positive. In investigated samples 37.3% Demodex spp. positivity was detected. Only two were found to be D brevis and the others were D folliculorum. The study revealed statistically significant relationships between the positivity of parasites with the occupational group, age and sex. Conclusion: Since the prevalence of Demodex among healthy individuals without any complaint was found to be 37%, we believe Demodex spp should be investigated in porter examinations of people who have dermatological complaints. Copyright (C) 2012, Elsevier Taiwan LLC & Formosan Medical Association. All rights reserved.Öğe Investigation on the machinability of steel/steel laminates by CO2 laser(INDERSCIENCE ENTERPRISES LTD, 2014) Simsir, Mehmet; Ozer, Ali; Kumruoglu, Levent CenkIn this study, an experimental investigation of machinability of steel/steel laminates using CO2 laser was presented. O-2 assist gas was used for cutting of laminates. Laser power and feed rate were changed gradually as cutting parameters. Heat affected zone (HAZ) size and kerf width were measured. Effect of linear energy density (ratio of power to feed rate) was determined on the kerf width, the HAZ size, and the cutting surface quality. Also, the quality of surface was examined under optical microscopy, and scanning electron microscopy. It is concluded that when linear energy density is increased, the kerf width and the HAZ size increase. Dross formation and surface irregularities increase with increasing laser power and decreasing feed rate.Öğe Investigations on the effects of mouthrinses on the colour stability and surface roughness of different dental bioceramics(KOREAN ACAD PROSTHODONTICS, 2017) Soygun, Koray; Varol, Osman; Ozer, Ali; Bolayir, GirayPURPOSE. In this study, three bioceramic materials, [IPS Empress CAD (Ivoclar), IPS e.max CAD (Ivoclar), and Lava Ultimate CAD (3M ESPE)] were treated with three commercial mouthrinses [Listerine, Tantum Verde, and Klorhex]; and changes in colour reflectance and surface roughness values were then quantitatively assessed. MATERIALS AND METHODS. One hundred and twenty ceramic samples, with dimensions of 2 x 12 x 14 mm, were prepared and divided into nine sample groups, except three control samples. The samples were immersed in the mouthrinse solutions for 120 hrs, and changes in colour reflectance and surface roughness values were measured by UV light spectrophotometry (Vita Easyshade; VITA Zahnfabrik) and by profilometer device (MitutoyoSurftest SJ- 301), respectively. The change of surface roughness was inspected by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). RESULTS. There was a positive correlation between the Delta E and increase in the surface roughness. Two of the ceramic materials, IPS Empress and Lava Ultimate, were affected significantly by the treatment of the mouthrinse solutions (P<.05). The most affecting solution was Tantum Verde and the most affected material was Lava Ultimate. As expected, the most resistant material to Delta E and chemical corrosion was IPS e max CAD among the materials used. CONCLUSION. This work implied that mouthrinse with lower alcohol content had less deteriorating effect on colour and on the surface morphology of the bioceramic materials.Öğe Microhardness evaluation of resin composites polymerized by three different light sources(JAPANESE SOC DENTAL MATERIALS DEVICES, 2007) Hubbezoglu, Ihsan; Bolayir, Giray; Dogan, Orhan Murat; Dogan, Arife; Ozer, Ali; Bek, BuelentThis study examined the surface microhardness of four kinds of resin composites with different fillers and resin matrices. Ten specimens of 2 mm thickness and 4 mm diameter of each resin composite were polymerized using a halogen light, a blue light-emitted diode, and a plasma are unit. Microhardness evaluation was performed at top and bottom surfaces for each specimen using a Vickers microhardness tester. Furthermore, morphologies of the polished top surfaces of composites cured with blue ligbt-emitted diode were observed using scanning electron microscopy. Results indicated that composites cured with halogen or blue light-emitted diode light yielded higher microhardness values, although it also appeared to depend on the type of composite cured. Plasma arc curing according to manufacturer's instructions yielded the lowest microhardness values for all the materials. Among the materials tested, the nanofilled resin composite displayed the highest microhardness values for each curing regime.Öğe MICROSTRUCTURAL CHARACTERISATION OF Co-Cr-Mo CASTING DENTAL ALLOYS(LUBLIN UNIV TECHNOLOGY, POLAND, 2017) Szala, Miroslaw; Beer-Lech, Karolina; Gancarczyk, Kamil; Kilic, Onur Baran; Pedrak, Pawel; Ozer, Ali; Skic, AnnaThe study compares the microstructure of three commercial dental cobalt matrix alloys with related chemical composition declared by the manufacturer. Casts were produced with lost wax method, then melted and caged with centrifugal induction casting machine. The Co-Cr-Mo alloys were casted according to the manufacturers procedure. The samples chemical composition and phase composition. respectively. using WD-XRF (Wavelength Dispersive X-Ray Fluorescence) and XRD (X-ray Diffarction) methods were analysed. Casts microstructure by mean of LOM (Light Optical Microscopy). SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive X-ray Spectroscopy) were investigated. Vickers hardness HV10 was measured. Quantitative microstructure evaluation was performed by means of computer image processing. The results of the chemical composition indicate the high stability of the chemical composition for alloy A. In case of alloys B and C. there was a significant difference in carbon content. Quantitative differences in image of microstructure between of castings A and B, C were noticed. The greater amount of precipitates was recorded for castings with higher carbon content. In all investigated castings, the presence of matrix solution and M23C6 carbide precipitations was found.Öğe New Records of Diatoms (Bacillariales, Rhopalodiales & Surirellales) with Ultrastructure Details from the Black Sea Coast of Turkey(Istanbul Univ Press, Fac Aquatic Sciences, 2022) Dirican, Seher; Kaleli, Aydin; Yilmaz, Elif; Ozer, Ali; Dayioglu, HayriDiatoms associated with the order Bacillariales, Rhopalodiales and Surirellales are well known to be present in marine and brackish waters. In this study, diatoms in the western Black Sea coasts of Turkey were investigated with ultrastructure details. Species belonging to the Bacillariales, Rhopalodiales and Surirellales were subject to light microscopy (LM) and scanning electron microscopy (SEM) analysis, and a total of twenty-four taxa were investigated. This study examines details on the morphology and biogeography of the taxa with remarks on their distribution in Turkey. The results revealed that four species were reported on the Turkish coasts for the first time. These species were Nitzschia liebethruthii, N. volvendirostrata, Epithemia guettingeri and Campylodiscus scalaris.Öğe Phase variation and mechanical properties of waste calcium carbonate to substitute quartz in composite slab production(Wiley, 2023) Bas, Sedanur; Guler, Taki; Ozer, Ali; Akturk, Selcuk; Kriven, Waltraud M.Owing to the fast-emerging nature and rapid advancements in the construction industry, huge volumes of marble dust (MD) are generated as reject during slab cutting in marble processing, causing significant environmental hazards. Nowadays, quartz composite slabs have increasingly been preferred in building works due to their excellent hygienic property and mechanical strength. Composite slab is produced using micronized quartz as filler, the grinding of which is an energy-intensive process. Substitution of micronized quartz with MD at different percentages was investigated in natural form and after roasting. Natural MD offered appreciable physical properties closer to those of a quartz composite slab. Physical properties slightly retrograded by quartz supplementation in the raw form. Roasting the filler led to the formation of rounded Ca-silicate. Wollastonite was the first phase formed after sintering at the lowest MD percentage and shortest roasting times. Larnite became dominating phase first by increasing MD percentage and roasting time, and then calcio-olivine formed. Physical characterization test results demonstrated that hardnesses of new phase and particle shape were the key parameters that improved slabs' mechanical properties of. Hard rounded larnite particles improved mechanical behavior of slabs having the synergic effect of quartz, whereas wollastonite did not show a significant effect.Öğe Removal of food dyes from aqueous solution by chitosan-vermiculite beads(Elsevier, 2020) Senol, Zeynep Mine; Gursoy, Nevcihan; Simsek, Selcuk; Ozer, Ali; Karakus, NihatIn this study, Chitosan (Ch)-Vermiculite (V) composite beads material which is a low-cost and naturally effective adsorbent were used for efficient removal of Sunset Yellow FCF (Sy) and Brilliant Blue FCF (Bb) food dyes from aqueous solution. Ch-V composite beads were characterized by using FTIR, SEM, XRD and PZC analysis. The adsorbent properties of Ch-V composite beads for Sy and Bb dyes were evaluated in terms of pH, concentration, kinetic (time) and thermodynamic (temperature) of adsorption. The experimental data presented were obtained from Langmuir, Freundlich and Dubinin-Radushkevich (DR) isotherm models. The maximum adsorption capacity for the Langmuir equation was found to be 0387 mol kg(-1) for Sy and 0229 mol kg(-1) for Bb, respectively. The results showed that the experimental data were better fit the Langmiur model for Sy and the Freundlich model for Bb. Adsorption energies obtained from DR model for Sy and Bb showed that adsorption processes were chemically. The pseudo-second order and intra-particle diffusion models of adsorption kinetics are in accordance with Sy and Bb. As a result of thermodynamic evaluation of Sy and Bb adsorption, it was found that adsorption processes were endothermic, entropy increased and reaction was spontaneous. (C) 2020 Elsevier B.V. All rights reserved.Öğe The surface and phase analysis studies on dental bioceramics subjected to different mouthrinse solutions(SPRINGER, 2018) Ozer, Ali; Soygun, Koray; Bolayir, GirayIn this study, three bioceramic materials, [IPS Empress (R) CAD (Ivoclar), IPS e.max (R) CAD (Ivoclar), and Lava Ultimate (R) CAD (3 M ESPE)] were treated with three commercial mouthrinses [Listerine, Tantum Verde and Klorhex]; and surface phase changes were then assessed. The samples were prepared with dimensions of 2 x 12 x 14 mm. They were immersed in the mouthrinse solutions by using a home-made agitation instrument for 120 h, but for the control group, the rinsing solution was distilled water. Surface phase changes were measured by X-ray diffraction (XRD) device (Bruker AXS D8 Advance, USA), and the change of surface roughness was inspected by scanning electron microscopy (LEO 440 Computer Controlled Digital, UK). XRD patterns of IPS e.max (R) CAD, IPS empress (R) CAD, and Lava Ultimate (R) CAD were evaluated in the study and phases were determined as different mouthwash deterioration then the effects of peak formation was indicated. Phases were seen some differentiation in terms of the crystalline structure. SEM images to investigate the surface roughness of the samples were employed. When the distilled water was applied, the surface was smoother and compact, but the surface of the samples subjected to Tantum Verde, Klorhex, and Listerine showed that the surface was deformed by erosive wear and corrosion of the ingredients. This work implied that mouthrinse with lower alcohol content had less deteriorating effect on the bioceramic materials. In terms of phase and surface roughness change, Lava Ultimate (R) CAD has been effected the most corroded surface among used bioceramics owing to organic content concentration.Öğe Synthesis and characterization of a polyacrylamide-dolomite based new composite material for efficient removal of uranyl ions(Springer, 2020) Senol, Zeynep Mine; Simsek, Selcuk; Ulusoy, Halil Ibrahim; Ozer, AliA new, effective, and economic adsorbent (PAA-Do), consist of Polyacrylamide and Dolomite was synthesized chemically and used for removal of uranyl ions from aquatic medium. Characterization of new material was carried out by FTIR, SEM-EDX and XRD techniques. The maximum adsorption capacities (Q(m)) for PAA-Do was found by the Langmuir equation to be 0.477 mol kg(-1). Adsorption kinetic was well-described by the pseudo first order kinetic. Recovery of adsorbent can be carried out by 1.0 mol L-1 HCl. The results of this study indicate that PAA-Do composites are good adsorbent candidates for uranyl removal.
