Yazar "Özkan, Arif" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim
    Öğe
    Batı Karadeniz bölgesindeki dalga enerjisi potansiyelinin araştırılması
    (2006) Uygur, İlyas; Demirci, Recep; Saruhan, Hamit; Özkan, Arif; Belenli, İbrahim
    Çevreye zarar vermeyen doğal, temiz ve sürekli yenilenebilir enerji türlerinin başlıcaları, rüzgar, güneş, biyolojik, su ve dalga enerjisidir. Dalga enerjisi, ilk yatırım ve bakım giderlerinden başka masrafı olmayan, girdi bedeli gerektirmeyen, doğaya her hangi bir kirletici bırakmayan, ucuz, temiz, çevreci ve büyük potansiyele sahip bir enerji kaynağıdır. Üç tarafı denizlerle çevrili Türkiye için de dalga enerjisi, enerji sıkıntısı çektiğimiz şu günlerde ve ileriki yıllarda bir çözüm olabilecek durumdadır. Bu bağlamda Batı Karadeniz (Akçakoca) bölgesinde beş yıllık gözlemsel çalışmalar yapılmış ve bölgenin dalga enerji potansiyeli hesaplanmıştır. Meteoroloji verilerinin incelenmesi neticesinde bölgedeki dalga enerjisi güç potansiyeli, mevcut teknolojik sistemler için yetersiz olarak gözükmektedir. Gelişen teknolojiyle birlikte üretilen yeni enerji dönüştürücülerinin de gelişeceği gözünde bulundurularak, yetersiz olarak tespit edilen dalga enerjisi potansiyeli daha verimli bir şekilde değerlendirilebilir. Bu çalışma bundan sonraki araştırmalar için bir temel teşkil edebilecektir.
  • Küçük Resim
    Öğe
    Flexor tendons repair : effect of core sutures caliber with increased number of suture strands and peripheral sutures. A sheep model
    (Elsevier Masson, Corporation Office, 2014) Uslu, Mustafa; Işık, Cengiz; Özşahin, Mustafa; Özkan, Arif; Yaşar, Mehmet Akif; Sarman, Hakan
    Background: Surgeons have aimed to achieve strong repair so as to begin early active rehabilitation programs for flexor tendon injury. Multi-strand suture techniques were developed to gain improved gap resistance and ultimate force compared with the respective two-strand techniques. In vivo studies indicate that multiple strands may cause ischemia during the intrinsic healing process by decreasing the total cross-sectional area of the injured site, unless the total cross-sectional area of the sutures is not decreased. Hypothesis: The hypothesis was to design an in vitro study to understand the biomechanical relationship between suture calibers of core sutures with increased number of suture strands and peripheral suture on final repair strength. Materials and methods: Sixty fresh sheep forelimb flexor digitorum profundus tendons were randomly placed into three groups (A, B, and C), each containing 20 specimens, for tendon repair. Two-, four-, and eight-strand suture techniques were respectively used in Groups A, B, and C. A simple running peripheral suture technique was used in Subgroups A2, B2, and C2. For each repaired tendon, the 2-mm gap-formation force, 2-mm gap-formation strength, maximum breaking force and maximum breaking strength were determined. Results: Differences in 2-mm gap-formation force and 2-mm gap-formation strength were found between Subgroups A1 and A2, B1 and B2, and Cl and C2. Between Groups A and B, A and C, and B and C, there was no difference as well. Conclusion: Both the number of strands and the ratio between the total suture volume and tendon volume at the repair site are important for ideal repair. If the total cross-sectional area of the sutures is equal in 2-strand, 4-strand, and 8-strand procedure, there is no difference in the strength of the repair. A decrease in caliber size suture requires more passes to achieve the same strength. Instead, it is much better to use peripheral suture techniques to improve the strength of the repair with larger diameter 2-strand core sutures. (C) 2014 Published by Elsevier Masson SAS.
  • Küçük Resim
    Öğe
    Using a combination of intralaminar and pedicular screw constructs for enhancement of spinal stability and maintenance of correction in patients with sagittal imbalance: clinical applications and finite element analysis
    (Lippincott Williams & Wilkins, 2016) İnanmaz, Mustafa Erkan; Köse, Kamil Çağrı; Atmaca, Halil; Özkan, Arif; Işık, Cengiz
    Study Design:Case series and finite element analysis.Objective:To report the clinical results of using intralaminar screw-rod (ILS) constructs as supplements to regular pedicle screw (PS) constructs in high risk for implant failure patients and to report the results of a finite element analysis (FEA) of this new instrumentation technique.Summary of Background Data:Despite advances in surgery and implantation techniques, osteoporosis, obesity, revision surgeries, and neuromuscular conditions (such as the Parkinson disease) are challenges against achieving solid arthrodesis and maintaining correction. Additional fixation strategies must be considered in these patients. There is only one study in the literature suggesting that ILS can be used as alternative anchor points and/or to increase fixation strength in conjunction with the PSs.Materials and Methods:Five patients (3 male and 2 female) with mechanical comorbidities underwent PS+ILS to treat sagittal imbalance. In radiologic analysis, thoracic kyphosis, lumbar lordosis, and sagittal vertical axis were analyzed. FEA of ILS augmentation technique were carried out.Four different models were created: (1) the full-construct model with ILS+PS 2 levels above and below the osteotomy of T10; (2) only PS 2 levels above and below T10; (3) ILS+PS 1 level above and below the osteotomy; and (4) short-segment PS with only PSs 1 level above and below the osteotomy. The stress/load distributions on the implants in vertebrae were analyzed.Results:The mean age of the patients included in this study was 41 years and the mean follow-up was 28.2 months. A total of 87 PSs and 39 ILSs were used. Both sagittal vertical axis and kyphosis angles showed significant improvements maintained at the latest follow-up. No pseudarthrosis or instrumentation failures were observed. FEA indicated that addition of ILS construct to a PS construct enabled decreased load bearing and increased implant life.Conclusions:Addition of an ILS construct to PS construct decreases osteotomy line deformation and reduces stress on pedicle fixation points, and the combination improves fixation stability over the conventional PS-rod technique.