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    Öğe
    Al2O3 Takviyeli Alüminyum Esaslı Kompozit Malzemelerde Mekanik Alaşımlama Süresinin Korozyon Davranışına Etkilerinin İncelenmesi
    (Kırıkkale Üniversitesi, 2019) Karacif, Kubilay; Karabulut, Hasan; Çıtak, Ramazan
    Bu çalışmada toz metalurjisi yöntemi ile üretilen alümina (Al2O3) takviyeli alüminyum esaslı kompozit malzemelerde mekanik alaşımlama süresinin tuzlu ortamdaki korozyon davranışına etkileri incelenmiştir. Numunelerin toz metalurjisi yöntemi ile üretiminde, takviye malzemesi olan Al2O3 tozları ve ana malzeme olan alüminyum tozları karışımına 1 saat karıştırma veya 2, 4, 6, 10 saat mekanik alaşımlama işlemleri uygulanmıştır. Presleme ve sinterleme işlemleri sonrasında elde edilen Al2O3 takviyeli alüminyum esaslı kompozit numunelere tuzlu ortamında (%3,5 NaCl) potansiyodinamik yöntem ile elektrokimyasal korozyon testleri uygulanmıştır. Çalışma sonucunda, mekanik alaşımlama süresinin artması ile Al2O3 takviyeli alüminyum esaslı kompozit malzemenin korozyon dayanımının azaldığı belirlenmiştir.
  • Küçük Resim
    Öğe
    The impact of allogenic red cell transfusion and coated bypass circuit on the inflammatory response during cardiopulmonary bypass: A randomized study
    (2009) Senay, Şahin; Toraman, Fevzi; Günaydın, Serdar; Kilercik, Meltem; Karabulut, Hasan; Alhan, Cem
    Objective: This study is designed to determine and compare the effects of transfusion and coated circuits on the inflammatory response during cardiopulmonary bypass. Methods: Forty patients were randomized into two groups according to the type of extracorporeal circuit used and later prospectively enrolled into two subgroups according to the need for red cell transfusion during CPB (leading to 4 groups - 10 patients per group; group 1: with no transfusion and standard oxygenator, group 2: with transfusion and standard oxygenator, group 3: with no transfusion and coated oxygenator, group 4: with transfusion and coated oxygenator). Serum lactate, interleukin 6, human tumor necrosis factor alpha (TNF-?), D-dimer and CRP levels were measured at three time points (T1: start of CPB, T2: before removal of aortic cross-clamp, T3: 45 min after the completion of proximal anastomoses). Protein adsorption of oxygenator fibers was measured. Outcome parameters were recorded. Results: Interleukin 6, TNF-?, D-dimer and lactate levels increased at T2 and T3 in all groups (P<0.05 within groups). The increase in interleukin 6 was significant at T2 in group 2 when compared to group 1 (8.0 ± 3.9 vs. 4.4 ± 1.8, P=0.03). The increase in TNF-alpha was higher at T2 in group 1 when compared to group 3 (16.0 ± 4.2 vs. 11.7 ± 2.8, P=0.05) and in group 2 when compared to group 3 at T2 and T3 (15.3 ± 4.6 vs. 11.7 ± 2.8, P=0.06; 17.6 ± 5.0 vs. 13.7 ± 3.9, P=0.06). Protein adsorption was higher in group 1 and group 2 (group 1 vs. group 3, 2.2 ± 0.8 vs. 1.4 ± 0.3, P=0.01; group 2 vs. group 3, 2.4 ± 0.7 vs. 1.4 ± 0.3, P=0.02; group 2 vs. group 4, 2.4 ± 0.7 vs. 1.8 ± 0.3, P=0.04), it was also higher at group 4 when compared to group 3 (1.8 ± 0.3 vs. 1.4 ± 0.3, P=0.03). Conclusions: Allogenic red cell transfusion enhances inflammatory response during CPB; coated circuit systems have a limiting effect on this inflammatory reaction. © 2009 Published by European Association for Cardio-Thoracic Surgery. All rights reserved.