Yazar "Yildirim, Mehmet" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim Yok
    Öğe
    Anti-cyclic citrullinated peptide antibodies in rheumatoid arthritis, brucellar arthritis and Behcet's disease
    (ACADEMIC JOURNALS, 2011) Aridogan, Buket Cicioglu; Cetin, Emel Sesli; Yildirim, Mehmet; Kaya, Selcuk; Ceyhan, Ali Murat; Demirci, Mustafa; Savas, Serpil
    In Behcet's disease (BD) and Brucellosis, joint involvement is very common and it may share similarities with rheumatoid arthritis (RA). Anti-cyclic citrullinated peptides (CCP) are evaluated as more specific autoantibodies than rheumatoid factor (RF) in RA. The aim of this study is to determine whether anti-CCP antibodies are useful in the differential diagnosis of RA from other arthritis or not. 153 serum samples were used in the study; 34 from RA patients, 26 from brucellar arthritis, 20 from BD with arthritis, 41 from BD without arthritis and 32 from healthy controls. In vitro quantitative, anti-CCP levels were measured by using fluoroenzyme-immunoassay (FEIA) method. Among RA patients, 73.5% were anti-CCP-positive and 70.5% were RF-positive. While there was a statistical difference in the anti-CCP and RF positivity rates between RA and brucellar arthritis patients, BD patients and healthy controls (p = 0.0001), there was no statistical difference between BD patients with arthritis and BD patients without arthritis. Also none of the Brucellar arthritis patients was positive for anti-CCP antibodies, one of them were positive for RF. Our results indicate that anti-CCP antibodies are not associated with brucellar arthritis or BD with joint involvement and since they show high specificity and good sensitivity for RA, they can be evaluated as a better marker than RF especially for the differentiation of RA from other types of arthritis such as BD and brucellar arthritis.
  • Küçük Resim Yok
    Öğe
    Effect of Mo addition on microstructure, ordering, and room-temperature mechanical properties of Fe-50Al
    (ELSEVIER SCIENCE BV, 2018) Yildirim, Mehmet; Akdeniz, M. Vedat; Mekhrabov, Amdulla O.
    The effects of Mo addition on microstructures, phase relationships, order-disorder phase-transition temperatures and room-temperature mechanical properties of Fe50Al50-nMon alloys (n=1, 3, 5, 7, and 9, mole fraction, %) were investigated after solidification and heat treatment. Structural characterization of the samples was performed via X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry. Room-temperature mechanical properties were investigated by conducting compression and microhardness tests. Mo3Al particles precipitated in all alloys because of the limited solid solubility of Mo in the Fe-Al-based phases. The as-cast Fe50Al50-nMon alloys exhibited brittle behavior with high yield strength and limited fracture strain at room temperature. Compared with the as-cast alloys, all the heat-treated alloys except for the Fe50Al41Mo9 alloy exhibited enhanced mechanical properties at room temperature. The heat-treated Fe50Al43Mo7 alloy exhibited the highest fracture strain and compressive strength of 25.4% and 2.3 GPa, respectively.
  • Küçük Resim Yok
    Öğe
    Microstructural evolution and room-temperature mechanical properties of as-cast and heat-treated Fe50Al50-nNbn alloys (n=1, 3, 5, 7, and 9 at%)
    (ELSEVIER SCIENCE SA, 2016) Yildirim, Mehmet; Akdeniz, M. Vedat; Mekhrabov, Amdulla O.
    The microstructural evolution and room-temperature mechanical properties of Fe50Al50-nNbn alloys (n=1, 3, 5, 7, and 9 at%) were investigated after solidification and subsequent heat treatment. For all the compositions, the (Fe, Al)(2)Nb Laves phase formed because of the incomplete solid solubility of Nb in the Fe-Al-based phases and tended to develop an eutectic mixture with the Fe-Al-based phase. According to the results of EDS analysis and microstructural investigations, the Nb concentration of the eutectic composition was 9 at%, and the solid solubility of Nb in the B2-type Fe-Al-based phase was 3 at%. In addition, the eutectic phase transition temperature was approximately 1265 degrees C. Compared with the as cast state, all the heat-treated alloys exhibited ultrahigh compressive strength and considerably increased compressive fracture strains. The heat-treated hypoeutectic Fe50Al42Nb3 alloy exhibited the highest compressive strength and fracture strain of 3.02 GPa and 33.1%, respectively, and the eutectic Fe(50)oAl(41)Nb(9) alloy exhibited the lowest compressive strength and fracture strain of 2.66 GPa and 21.8%, respectively, because of the absence of the comparably softer Fe-Al-based primary dendrites. The superior mechanical properties of the heat-treated alloys were attributed to the bimodal distribution of the microstructure, structural incoherency between the crystalline phases, and elimination of solidification artifacts and lattice defects. (C) 2016 Elsevier B.V. All rights reserved.