Browsing by Author "Özdemir, M."

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Characteristics of Flow Regimes in Spiral Packed Beds With Spheres
(Begell House Inc., 2024) Gökaslan, M.Y.; Özdemir, M.; Kuddusi, L.
Packed beds are used in many fields such as heat exchangers, cooling systems, filtration, and reactors. Porous media can be used in order to enhance the heat transfer between the solid and the fluid, but it also creates higher pressure drops for the same flow rate. The flow regime significantly affects the heat transfer and pumping power of the fluid. It is known that when the channel is either curved or packed separately, the pressure drop increases. There are many studies on pressure drop and flow regimes in porous media or curvilinear channels. However, there are not many studies on pressure drop and flow regimes in a curvilinear packed bed. In this work, the pressure drops and flow regimes were determined when the channel is both curved and porous media. The packed beds were formed with two different radii of curvature, 71 and 171 mm in diameter, and were filled from steel balls with different particle diameters of 2.00, 2.38, and 3.17 mm. The pressure drop in these spiral packed beds was measured experimentally and flow regimes were determined for each test chamber and ball diameter. In each flow regime, permeabilities, Forchheimer coefficients, and the coefficients corresponding to Ergun constants were calculated. The effect of the curvature ratio was interpreted as the difference from the straight packed beds. Determining the flow regime ranges of curved packed beds can help to better interpret the heat transfer and pumping power of the fluid in these regimes. © 2024 by Begell House, Inc. www.begellhouse.com.
Containment Measures Established During the Covid-19 Outbreak and Its Impact on Lipid Profile and Neutrophil To Lymphocyte Ratio
(Verduci Editore s.r.l, 2020) Aladağ, N.; Şipal, A.; Atabey, R.D.; Akbulut, T.; Asoğlu, R.; Özdemir, M.
OBJECTIVE: Almost all countries announced social restrictions and distancing measures which could unintentionally lead to a decline in admissions to hospital for acute disorders other than signs of pneumonia. We aimed to evaluate lipid profile, neutrophil to lymphocyte ratio (NLR) and cardiovascular admissions to the coronary care unit (CCU) of a tertiary center in Turkey during the COVID-19 era and to compare these results with admissions in the same time interval of the previous year. MATERIALS AND METHODS: We retrospectively analyzed CCU admissions due to new-onset atrial fibrillation, ST-elevation myocardial infarction, non-ST elevation acute coronary syndrome (NSTEACS) and acute heart failure during the COVID-19 outbreak and the same time interval of the past year. Laboratory measurements including lipid profile and NLR values were retrieved from the institutional digital database. RESULTS: Compared to the same time interval of 2019 (March-April, 2019), the number of patients admitted to the CCU with acute cardiovascular disorders (atrial fibrillation, STEMI, NSTEACS and acute heart failure) were lower in the COVID-19 period. The levels of NLR, total cholesterol, and low-density lipoprotein (LDL) cholesterol were significantly higher and high-density lipoprotein (HDL) cholesterol was significantly lower in subjects admitted to the CCU during March-April 2020 compared to subjects admitted in March-April 2019. CONCLUSIONS: Our findings show that subjects admitted to the CCU in the COVID-19 era have an unfavorable lipid profile and elevated NLR compared to those admitted in 2019. These patients appear to be at high risk for future cardiovascular events. © 2020 Verduci Editore s.r.l. All rights reserved.
Traumatic Corneal Rupture After Radial Keratotomy
(2001) Çinal, A.; Özdemir, M.; Demirok, A.
We present a case report of corneal rupture by blunt trauma in an eye which underwent radial keratotomy (RK). The patient was admitted to our clinic following right eye trauma, five years after RK. All measurements and examination results were recorded. The examination determined a corneal rupture and iris prolapse at the RK incision site at nine o clock. The iris was repositioned and cornea repaired. At the postoperative visit after one month, there was anterior synechia and eccentric pupil towards perforation site. It is emphasized that incision sites of RK are more vulnerable than normal corneal areas to blunt trauma even several years after RK.