Browsing by Author "Aydin I."

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    Determination of fracture toughness of calcium phosphate coatings deposited onto Ti6Al4V substrate by using indentation technique
    (2012) Aydin I.; Cetinel H.; Pasinli A.
    In this study, fracture toughness values of calcium phosphate (CaP) coatings deposited onto Ti6Al4V substrate were determined by using Vickers indentation method. In this new patent holding method, the activation processes were performed with NaOH and NaOH+H2O2 on the Ti6Al4V material surface. Thicknesses of CaP coatings were measured from cross-sections of the samples by using optical microscopy. Vickers indentation tests were performed by using microhardness tester. Young's modulus values of the coatings were determined by using ultra microhardness tester. As a result, fracture toughness (K1C) values of the CaP coatings produced by using two different activation processes, were calculated by using experimental study results. These were found to be 0.43 MPa m1/2 and 0.39 MPa m1/2, respectively. It was determined that the CaP coating on Ti6Al4V activated by NaOH+H2O2 had higher fracture toughness than the CaP coating on Ti6Al4V activated by NaOH. © 2012 American Institute of Physics.
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    Sol-gel synthesized Sr4Al14O25:Eu2+/Dy3+ blue–green phosphorous as oxygen sensing materials
    (Elsevier B.V., 2016) Aydin I.; Ertekin K.; Demirci S.; Gultekin S.; Celik E.
    In this study, we utilized newly synthesized Sr4Al14O25:Eu2+/Dy3+ blue–green phosphors along with silver nanoparticles (AgNPs) for fabrication of oxygen sensitive materials. To the best of our knowledge oxygen sensing mechanism of the offered design is totally different from the previously published works. One-component silicone: poly (1-trimethylsilyl-1-propyne), two component phenyl bearing silicone, plasticized polymethylmethacrylate, and ethylcellulose (EC) were tested as matrix materials. Electrospun fibers, porous and smooth thin films were produced by electrospinning or knife coating technique. Oxygen induced luminescence of the phosphors at 544 nm was followed as the analytical signal. Utilization of silver nanoparticles in silicone along with phosphors resulted with a 7.14 fold enhancement in the signal intensity and significant spectral response towards oxygen competing with the signals of the oxygen sensors utilizing metalloporphyrins or ruthenium complexes. We observed high sensitivity and stability, increased surface area and an enhancement in all sensor dynamics. Linearity of the calibration plots was superior for the pO2 range of 0.0–20.0% with respect to the previously reported ones. When stored at the ambient air of the laboratory there was no significant drift in signal intensity after 12 months. Our sensitivity and stability tests are still in progress. © 2016 Elsevier B.V.
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    HA coating on Ti6Al7Nb alloy using an electrophoretic deposition method and surface properties examination of the resulting coatings
    (MDPI AG, 2019) Aydin I.; Bahçepinar A.I.; Kirman M.; Çipiloğlu M.A.
    Ti and its alloys, which are commonly used in biomedical applications, are often preferred due to their proximity to the mechanical properties of bone. In order to increase the biocompatibility and bioactivities of these materials, biomaterials based on ceramic are used in coating operations. In this study, by using an electrophoretic deposition method, instead of on the Ti6Al4V alloy which is commonly used in the literature, a hydroxyapatite (HA) coating operation was applied on the surface of the Ti6Al7Nb alloy, and the surface properties of the coatings were examined. Ti6Al7Nb is a new-generation implant on which there have not been many studies. The voltage values which were used in the coating operation were 50, 100, 150 and 200 V, and the time parameter was stabilized at 1 min. In our method, when preparing the solution, HA, ethanol, and polyvinyl alcohol (PVA) were used. At the end of the study, by using an electron microscope (SEM) the microstructures of the coatings were examined; elemental analyses (EDS) of the coating surfaces were performed; and by using an X-radiation diffraction (XRD) method, the phases which the coatings contained and the concentration of these phases were determined, and the coating thickness, roughness, and hardness values were also determined. Also, by conducting a Scratch test, the strength of the surface combination was examined. At the end of the study, in each parameter, a successful HA coating was seen. By comparing parameters with each other, the ideal voltage value in this coating was determined. It was determined that the most suitable coating was obtained at 100 V voltage and 1 min deposition time. © 2019 by the authors.
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    Surface characterization of EPD coating on AZ91 Mg alloy produced by powder metallurgy
    (CSIC Consejo Superior de Investigaciones Cientificas, 2020) Aydin I.; Bahçepinar A.I.; Gül C.
    Intense implants which are used widely in biomedical applications such as Ti and its alloys and 316 L stainless steel can harm the surrounding tissues, hence may also cause infection. In order to eliminate this risk, it is necessary to produce new generation implant materials that are lighter than their existing biomaterials for use in biomedical applications and whose mechanical properties and structure are close to bone. In this study AZ91 Mg alloy implant material is created by using powder metallurgy method. In addition, in order to improve the bio-compatibility and bio-activity, the generated implant material was also coated with hydroxyapatite (HA) which is known as a ceramic based biomaterial. In this study, AZ91 Mg alloy is created by using powder metal-lurgy method. HA coating was applied to the alloy surface using the electrophoretic deposition method. The surface properties and corrosion resistance of the coatings made were examined. The applied voltage values in the coating process were determined as 100, 150, 200 and 250 V, the time parameter was stabilized as 2 minutes. HA, ethanol, polyvinyl alcohol (PVA), N, N-Dimethylformamide chemicals were used to prepare the coating solution. At the end of the study, microstructures of the coatings were examined by using scanning electron microscopy (SEM) and elemental analyzes (EDS) of the coating surfaces were performed. The X-ray diffrac-tion method (XRD) was used to determine the phases of the coatings and its concentration. Coating thickness and surface roughness values were also determined. Corrosion behavior of coated samples was determined by potentiodynamic electrochemical potential corrosion test in artificial body fluid. © 2020 CSIC.
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    Effect of the Microwave Heating on Diffusion Kinetics and Mechanical Properties of Borides in AISI 316L
    (Springer, 2020) Ipek Ayvaz S.; Aydin I.
    In this study, the effect of microwave heating on boride formation and diffusion kinetics in 316L stainless steel alloys was investigated. Boriding was carried out in microwave furnace with 2.9 kW power and 2.45 GHz frequency. Four different boriding temperatures (800, 850, 900 and 950 °C) were used. Boriding was performed for 2, 4 and 6 h for each temperature. Boron layer thicknesses of boride layers were determined by optical microscope. SEM images were taken from the cross sections of the borided samples. Boron activation energy was determined as 244.15 kJ/mol in microwave environment. Two times thicker boride layer was obtained by microwave boriding process compared to the conventional heating process. The mechanical properties of the boride layers formed by microwave boriding (Young’s modulus, hardness, yield strength, residual thermal stress) were determined by nanoindentation tests. © 2020, The Indian Institute of Metals - IIM.
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    Tribological and adhesion properties of microwave-assisted borided AISI 316L steel
    (Walter de Gruyter GmbH, 2022) Ipek Ayvaz S.; Aydin I.
    In this study, AISI 316L stainless steel alloy samples were borided with powder-pack boriding method using Ekabor II powder with the support of a microwave furnace with a power of 2.9 KW and a frequency of 2.45 GHz. Boriding was carried out at 850, 900 and 950 °C temperatures for 2, 4 and 6 h of operation. A distinct diffusion barrier consisting of Fe-Ni-Si elements was detected in borided samples at 950 °C for 4 and 6 h. As a result of the Daimler Benz Rockwell-C adhesion tests, regions with insufficient adhesion strength were detected in these samples. In other samples, adhesion qualities between boride layers and substrate were in the range of HF1-HF3. The lowest specific wear rates were determined as 5.208 (mm3 Nm-1) × 10-6 and 5.210 (mm3 Nm-1) × 10-6 for the samples borided for 6 h at 850 °C and 4 h at 900 °C, respectively. It was determined that the increase in thickness of the brittle FeB compound increased the wear with the three-body abrasive wear mechanism. © 2021 Walter de Gruyter GmbH, Berlin/Boston.
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    Investigation of the effect of shot blasting on the surface properties of the HA coatings processed by the EPD method
    (Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, 2022) Bahçepinar A.I.; Aydin I.
    316L stainless steel implant material surfaces shot blasted with glass beads underwent hydroxyapatite (HA) coating process by electrophoretic deposition method (EPD). The mechanical and metallographic test results of HA coatings applied to the shot blasted and sanded substrates have been discussed. The sanded process was carried out with 320 Grit SiC sandpaper. Shot blasted process was carried out in a vacuum shot blasting machine at 5 bar pressure with glass beads. Ethanol was used as a solvent during the coating process. The coating solution was prepared by mixing ethanol, HA, PVA, and N, N-Dimethylformamide chemicals in specific ratios to have a steady suspension. Regarding tests conducted on HA coatings, it was revealed that shot blasted surfaces had better results when compared to those of sanded surfaces. Hopefully, this new process for coatings will be a new impression for future studies. © 2022 Institute of Materials and Machine Mechanics, Slovak Academy of Sciences. All rights reserved.
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    Nationwide prospective audit for the evaluation of appendicitis risk prediction models in adults: Right iliac fossa treatment (RIFT) - Turkey
    (Oxford University Press, 2024) Yalcinkaya A.; Yalcinkaya A.; Balci B.; Keskin C.; Erkan I.; Yildiz A.; Kamer E.; Leventoglu S.; Caglikulekci M.; Zarbaliyev E.; Sevmis M.; Ulgen Y.; Altinel Y.; Meric S.; Akbas A.; Hacim N.A.; Vartanoglu Aktokmanyan T.; Aktimur Y.E.; Calikoglu F.; Gullu H.F.; Durma A.G.; Acar S.; Ciftci E.; Balik E.; Kulle C.B.; Ozata I.H.; Tufekci T.; Tatar C.; Sevinc M.M.; Sevik H.; Ertürk C.; Kiraz I.N.; Ozben V.; Aytac E.; Aliyeva Z.; Mutlu A.U.; Tanal M.; Celayir M.F.; Bozkurt E.; Yetkin S.G.; Ergin E.; Attaallah W.; Uprak T.K.; Omak A.; Simsek O.; Bozkurt M.A.; Kara Y.; Bozdag E.; Yirgin H.; Ozcan A.; Okkabaz N.; Ozdenkaya Y.; Haksal M.C.; Pekuz C.K.; Duru S.; Sivrikoz E.; Ozdemir Y.; Tan N.; Yarbug Karayali F.; Taghiyeva A.; Tirnova I.; Erenler Bayraktar I.; Bayraktar O.; Emsal E.Z.; Dalkilic M.I.; Yesiltas M.; Tok H.; Karakas D.O.; Pusane A.; Demirer A.I.; Sahin H.B.; Gok A.F.K.; Bozkurt H.A.; Yildirim M.; Uzunyolcu G.; Yanar H.T.; Ergun S.; Kutluk F.; Uludag S.S.; Zengin A.K.; Ozcelik M.F.; Sanli A.N.; Altuntas Y.E.; Memisoglu E.; Sari R.; Akdogan O.; Kucuk H.F.; Ozkan O.F.; Ulgur H.S.; Kirkan E.F.; Yuksekdag S.; Rencuzogullari A.; Aktas M.K.; Aba M.; Demirel A.O.; Eray I.C.; Aydogan B.; Cetinkunar S.; Yener K.; Sozutek A.; Irkorucu O.; Bayrak M.; Altintas Y.; Alabaz O.; Atasever A.; Erdogrul G.; Kupeli A.H.; Muhammedoglu B.; Kokdas S.; Kaya M.; Uysal E.; Yildirim A.C.; Zeren S.; Ekici M.F.; Algin M.C.; Kucuk G.O.; Eraslan H.; Aybar E.; Polat S.; Ceylan A.; Isik O.; Kural S.; Aktas A.; Bakar B.; Uzunoglu M.Y.; Gulcu B.; Ozturk E.; Devay A.O.; Taspinar E.; Balcin O.; Aksoy F.; Garip G.; Yalkin O.; Iflazoglu N.; Yigit D.; Kaya R.B.; Ugur M.; Kilic E.; Dedemoglu A.; Arslan R.E.; Temiz M.; Aydin C.; Demirli Atici S.; Kaya T.; Ozturk S.; Calik B.; Kilinc G.; Acar T.; Acar N.; Cengiz F.; Ureyen O.; Tan S.; Ilhan E.; Turk Y.; Durak A.T.; Yilmaz M.; Mercan M.; Atci R.; Sokmen S.; Bisgin T.; Egeli T.; Yildirim Y.; Safak T.; Celik K.; Yilmaz E.M.; Kirnap M.; Demirkiran A.E.; Sekerci U.U.; Karacan E.; Bilgic E.; Ozmen M.M.; Guldogan C.E.; Gundogdu E.; Moran M.; Erol T.; Dincer H.A.; Kirimtay B.; Yilmaz S.; Cennet O.; Yildiz A.; Sahin C.; Akyol C.; Koc M.A.; Ersoz S.; Turhan A.; Konca C.; Tezcaner T.; Erkent M.; Aydin O.; Avci T.; Altiner S.; Osmanov I.; Emral A.C.; Cetinkaya G.; Lapsekili E.; Sakca M.; Cimen S.; Ozen D.; Kozan E.B.; Dogan L.; Haberal E.; Kayhan O.; Aksel B.; Karabacak H.; Azili C.; Yazici F.; Apaydin M.; Kaya I.O.; Cetinkaya E.; Akin T.; Gunes G.; Turap H.; Aslan D.; Demirbag A.E.; Bolukbasi B.; Karaca B.E.; Ozturk E.; Ozeller E.; Kayacan G.S.; Borcek A.O.; Ece I.; Yormaz S.; Colak B.; Calisir A.; Sahin M.; Arslan K.; Hasirci I.; Ulutas M.E.; Metin S.H.; Gultekin F.A.; Ozkan Z.; Ilhan O.; Gundogdu T.; Liman R.K.; Kanat B.H.; Aydin A.; Sungurtekin U.; Ozgen U.; Aykota M.R.; Altintoprak F.; Gonullu E.; Cakmak G.; Dulger U.C.; Mantoglu B.; Demir H.; Akin E.; Eroz E.; Nazli O.; Dere O.; Dadasoglu M.A.; Kara E.; Tutcu S.; Solak I.; Gencer I.; Dalkiran A.; Sevinc B.; Karahan O.; Damburaci N.; Sari E.; Akay T.; Calta A.F.; Ozdemir A.; Ohri N.; Ermis I.; Bozbiyik O.; Ozdemir M.; Goktepe B.; Demir B.; Kilincarslan O.; Gunduz U.R.; Olcum M.; Dincer O.I.; Cakir R.C.; Dinc B.; Sahin E.; Uludag E.; Arslan Y.; Posteki G.; Oktay A.; Tatar O.C.; Guler S.A.; Utkan N.Z.; Tayar S.; Copelci Y.; Kartal M.; Kalayci T.; Yeni M.; Buyukkasap A.C.; Vural S.; Kesicioglu T.; Aydin I.; Gulmez M.; Saracoglu C.; Topcu O.; Kurt A.; Soylu S.; Kurt B.; Serin M.; Basceken S.I.; Gundes E.; Savda M.; Balkan A.Z.A.; Yildiz M.N.; Uzunkoy A.; Karaca E.; Berkan A.; Isik A.; Yildiz Y.A.; Ergul Z.; Yasar N.F.; Badak B.; Ozen A.; Velipasaoglu M.; Ure I.
    Background: Appendicitis is the most prevalent surgical emergency. The negative appendicectomy rate and diagnostic uncertainty are important concerns. This study aimed to assess the effectiveness of current appendicitis risk prediction models in patients with acute right iliac fossa pain. Methods: A nationwide prospective observational study was conducted, including all consecutive adult patients who presented with right iliac fossa pain. Diagnostic, clinical and negative appendicectomy rate data were recorded. The Alvarado score, Appendicitis Inflammatory Response (AIR), Raja Isteri Pengiran Anak Saleha Appendicitis (RIPASA) and Adult Appendicitis Score systems were calculated with collected data to classify patients into risk categories. Diagnostic value and categorization performance were evaluated, with use of risk category-based metrics including 'true positive rate' (percentage of appendicitis patients in the highest risk category), 'failure rate' (percentage of patients with appendicitis in the lowest risk category) and 'categorization resolution' (true positive rate/failure rate). Results: A total of 3358 patients from 84 centres were included. Female patients were less likely to undergo surgery than men (71.5% versus 82.5% respectively; relative risk 0.866, 95% c.i. 0.834 to 0.901, P < 0.001); with a three-fold higher negative appendicectomy rate (11.3% versus 4.1% respectively; relative risk 2.744, 95% c.i. 2.047 to 3.677, P < 0.001). Ultrasonography was utilized in 56.8% and computed tomography in 75.2% of all patients. The Adult Appendicitis Score had the best diagnostic performance for the whole population; however, only RIPASA was significant in men. All scoring systems were successful in females patients, but Adult Appendicitis Score had the highest area under the receiver operating characteristic curve value. The RIPASA and the Adult Appendicitis Score had the best categorization resolution values, complemented by their exceedingly low failure rates in both male and female patients. Alvarado and AIR had extremely high failure rates in men. Conclusion: The negative appendicectomy rate was low overall, but women had an almost three-fold higher negative appendicectomy rate despite lower likelihood to undergo surgery. The overuse of imaging tests, best exemplified by the 75.2% frequency of patients undergoing computed tomography, may lead to increased costs. Risk-scoring systems such as RIPASA and Adult Appendicitis Score appear to be superior to Alvarado and AIR. © 2024 The Author(s). Published by Oxford University Press on behalf of BJS Foundation Ltd.