Browsing by Author "Demir, Mehmet Emin"
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Publication The effect of graphite addition on the friction coefficient and wear behavior of glass fiber reinforced composites(Bursa Uludağ Üniversitesi, 2024-03-08) Demir, Mehmet EminThe use of fillers in fiber-reinforced epoxy matrix composites to enhance the wear performance of the composite is a widely employed method nowadays. In this study, the effect of incorporating graphite filler into a glass fiber-reinforced composite structure on the tribological properties of the composite was investigated. Composite materials produced using the hand lay-up method with three different levels of graphite filler were compared to unfilled composites in terms of wear behavior under different loads (7 N, 10 N, 15 N) and sliding distances (200 m, 400 m). The influence of load, filler content, and sliding distance on the friction coefficient and wear rate was discussed. When the results are examined, the significant effects of graphite filler on wear volume and friction coefficient are clearly observed. In the composite containing 12% graphite, the wear volume has decreased by almost 96%; this ratio has been around 93% for the composite with 4% graphite filler. As the reinforcement of graphite and force increase, the friction coefficient decreases, whereas with the increase in sliding distance, the friction coefficient declines. Microstructural analysis revealed that the filled composites exhibited less abrasion compared to the unfilled composites, and the surface porosity and craters were shallower.Publication The longitudinal evolution of post-COVID-19 outcomes among hemodialysis patients in Turkey(Elsevier Science Inc, 2022-06-03) Ozturk, Savas; Turgutalp, Kenan; Arici, Mustafa; Gorgulu, Numan; Tonbul, Halil Zeki; Eren, Necmi; Gencer, Vedat; Ayli, Mehmet Deniz; Pembegul, Irem; Dolarslan, Murside Esra; Ural, Zeynep; Colak, Hulya; Ozler, Tuba Elif; Can, Ozgur; Demir, Mehmet Emin; Altunoren, Orcun; Huddam, Bulent; Onec, Kursad; Demirelli, Bulent; Aydin, Zeki; Altun, Eda; Alagoz, Selma; Ayar, Yavuz; Eser, Zeynep Ebru; Berktas, Bayram; Yilmaz, Zulfukar; Ates, Eser Uslu; Yuksel, Enver; Sahin, Gizem Kumru; Aktar, Merve; Cebeci, Egemen; Dursun, Belda; Kocak, Sibel Yucel; Yıldız, Abdülmecit; Kazan, Sinan; Gok, Mahmut; Sengul, Erkan; Tugcu, Murat; Ozturk, Ramazan; Kahvecioglu, Serdar; Kara, Ekrem; Kaya, Bulent; Sahin, Garip; Sakaci, Tamer; Sipahi, Savas; Kurultak, Ilhan; Durak, Beyza Algul; Altiparmak, Mehmet Riza; Ecder, Sabahat Alisir; Karadag, Serhat; Dincer, Mevlut Tamer; Ozer, Hakan; Bek, Sibel Gokcay; Ulu, Memnune Sena; Gungor, Ozkan; Bakir, Elif Ari; Odabas, Ali Riza; Seyahi, Nurhan; Yildiz, Alaattin; Ates, Kenan; YILDIZ, ABDULMECİT; Bursa Uludağ Üniversitesi/Tıp Fakültesi/Nefroloji Anabilim Dalı.; HIG-9032-2022Introduction: Hemodialysis (HD) patients have increased risk for short-term adverse outcomes of COVID-19. However, complications and survival at the post-COVID-19 period have not been published extensively.Methods: We conducted a national, multicenter observational study that included adult maintenance HD patients recovered from confirmed COVID-19. A control HD group without COVID-19 was selected from patients in the same center. We investigated the characteristics and outcomes in the follow-up of HD patients and compare them with the non-COVID-19 group.Results: A total of 1223 patients (635 patients in COVID-19 group, 588 patients in non-COVID-19 group) from 47 centers were included in the study. The patients' baseline and HD characteristics were almost similar. The 28th-day mortality and mortality between 28th day and 90th day were higher in the COVID-19 group than non-COVID-19 group (19 [3.0%] patients vs. none [0%]; 15 [2.4%] patients vs. 4 [0.7%] patients, respectively). The presence of respiratory symptoms, rehospitalization, need for home oxygen therapy, lower respiratory tract infection, and arteriovenous (AV) fistula thrombosis was significantly higher in the COVID-19 group in both the first 28 days and between 28 and 90 days. In the multivariable analysis, age (odds ratio [OR] [95% CI]: 1.029 [1.004-1.056]), group (COVID-19 group vs. non-COVID-19 group) (OR [95% CI]: 7.258 [2.538-20.751]), and vascular access type (tunneled catheter/AV fistula) (OR [95% CI]: 2.512 [1.249-5.051]) were found as independent parameters related to 90-day mortality.Conclusion: In the post-COVID-19 period, maintenance HD patients who have had COVID-19 have increased rehospitalization, respiratory problems, vascular access problems, and high mortality compared with the non-COVID-19 HD patients.