Yazar "Sahin M." seçeneğine göre listele
Listeleniyor 1 - 5 / 5
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Bacterial translocation to kidney in rats with intestinal obstruction and the role of nitric oxide.(2009) Özbek E.; Ilbey Y.O.; Cekmen M.; Şimşek A.; Tekerekoglu M.; Sahin M.; Balbay M.D.Objective: Bacterial translocation (BT) is the passage of viable indigenous bacteria from one site to another, such as from gastrointestinal tract to the normally sterile regional mesenteric lymph nodes and than other internal organs. In this study we aimed to investigate the BT to kidney and the protective effect of nitric oxide (NO) inhibition. Material and methods: A total of 40 adult male Wistar albino rats weighing 320-350g were divided into four equal groups. Group 1 (n= 10): control group, group-2 (n = 10) sham control, group-3 (n = 10) simple obstruction, in which ileum was ligated 1-2 cm proximal to the ileocecal valve, group-4 (n = 10), simple obstruction and treated with L-NAME. Twenty four hour after the operation rats were sacrificed and kidneys were removed by sterile manner and trunk blood obtained for NO analysis. BT was defined as any positive culture from the blood and kidney. Results were compared with Mann- Whitney U test. Results: NO levels in control, sham group, simple obstruction group and obstruction plus L-NAME treated group were 14.04 ± 0.65 ?mol/L, 13.03 ± 0.080 ?mol/L, 31.17 ± 0.40 ?mol/L and 12.24 ± 0.70 ?mol/L, respectively. Renal culture results were negative in all controls and sham operated rats. However, all culture results were positive in obstruction group and in 4 in L-NAME-treated group. The most common microorganism that translocated was E. coli. Conclusion: This experimental study shows that BT to rat rat kidneys occurs in bowel obstruction and this can be inhibited by a NO inhibitor, L-NAME. Further studies are needed to define the clinical significance of these findings on urinary tract infection.Öğe Comparison of prosthetic materials used for abdominal wall defects or hernias (an experimental study).(1995) Sahin M.; Hasanoglu A.; Erbilen M.; Orakçi V.; Bülbüloglu E.; Ertaş E.The prosthetic materials polypropylene and polytetrafluoroethylene were comparatively studied for postinterventional infection, development of adhesions, and recurrence of hernias and tissue reactions in rats in which abdominal defects 1 by 2 cm in size had been repaired with one of these materials. As regards infection and hernias there was no significant difference vs. a control group of rats. There was no collagen deposition in polytetrafluoroethylene, and the mononuclear inflammatory cell reaction and fibroblastic activity outside the graft layer were steadily less intense with polytetrafluoroethylene than with polypropylene. Adhesions were significantly (p < 0.05) more marked with polypropylene.Öğe Gain-Scheduling H? control of a smart beam with parameter varying(International Center for Numerical Methods in Engineering, 2017) Onat C.; Sahin M.; Yaman Y.The use of smart structures provides more efficient solutions to most of the active vibration control problems in flexible systems due to the significant advances in sensor and actuator technologies. This paper presents a novel design approach of a gain scheduling H? controller for a parameter varying smart beam having surface bonded piezoelectric sensors and actuators. The robust approach intends to suppress the vibrations of the first flexural resonance of the smart beam which has a servo actuated end mass. The smart beam studied is a cantilever aluminum beam with four surface bonded Lead-Zirconate-Titanate (PZT) patches in bimorph configuration. In the design procedure, first, the parameter uncertain modeling of the flexible cantilever aluminum beam with a piezoelectric sensor and actuator is created by means of an analogical approach. Hence, the uncertain model was achieved from the simulation of the experimentally obtained beam model with a mass-spring-damper system having the equivalent smart beam characteristics. Then, the generalized plant model of the uncertain model is constituted, and a Linear Time Invariant (LTI) H? controller is computed. Finally, a gain scheduling H? controller was obtained by adapting a variable parameter filter to the LTI H? controller. The developed gain scheduling H? controller and its corresponding conventional H? controller are applied on the smart system with parameter varying. The obtained experimental results in time and frequency domain reveal that the proposed controller is able to suppress the vibrations of the smart beam at the first flexural mode. In addition to this, the experimental results show that proposed gain scheduling H? controller's performance is superior then conventional LTI H? controller. © 2017 International Center for Numerical Methods in Engineering. All rights reserved.Öğe Late focal pancreatic metastasis of renal cell carcinoma(1998) Sahin M.; Foulis A.A.K.; Poon F.W.; Imrie C.W.Metastatic carcinoma to the pancreas is uncommon. Pancreatic metastasis from a renal cell carcinoma is exceptional, but may occur many years after the initial diagnosis and treatment of the primary tumor. Presentation of our patient mimicked a head of the pancreas carcinoma so well that it was only after the resectional phase of a Whipple operation that the diagnosis of metastatic renal carcinoma was made 18 years after left nephrectomy. The patient is alive and well 18 months after surgery, having gained weight.Öğe Optimal control of a smart beam by using a Luenberger observer(University of Patras, Laboratory of Technology and Strength of Materials, 2013) Onat C.; Sahin M.; Yaman Y.This paper presents the design of an optimal vibration control mechanism, namely an LQR controller, with a Luenberger observer for a smart beam having surface bonded piezoelectric sensors and actuators. The approach intends to suppress the vibrations of the first flexural resonance of the smart beam. The smart beam studied was a cantilever aluminium beam with eight surface bonded Lead-Zirconate-Titanate (PZT) patches in bimorph configuration. The smart beam was excited at its first resonance frequency (approx. at 7 Hz) with a group of piezoelectric actuator patches and the response of the smart beam was monitored from a single piezoelectric sensor patch in order to obtain the necessary experimental frequency response for the system identification. The design of the controller was achieved by combining the optimal control law, architecture of Luenberger observer and inverse dynamic model of the smart beam. The verification of the developed controller was proved through the time and frequency domain responses and it was successfully shown that the intended target was achieved.
