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Öğe A Numerical Investigation on the Performance and Sustainability Analysis of Conventional and Finned Air-Cooled Solar Photovoltaic Thermal (PV/T) Systems(Mdpi, 2025) Imik, Edip; Yilmaz, MehmetThe increasing global demand for sustainable energy has increased the importance of solar photovoltaic thermal (PV/T) systems, which simultaneously increase electrical efficiency by removing excess heat and utilizing it for beneficial purposes. Although the addition of fins is generally known to increase efficiency, the influence of Z-finned geometries on PV/T system performance has not yet been fully characterized. In this study, the performance of conventional (PV/T-C) and Z-finned (PV/T-F) air-cooled PV/T systems was numerically investigated through comprehensive energy, exergy, and sustainability analyses. Simulations were conducted using ANSYS Fluent 2025 R1. The results revealed that, compared to the PV/T-C system, the PV/T-F system achieved an increase of 17.18% in overall efficiency. Furthermore, the incorporation of fins enhanced the overall exergy efficiency by 2.57% and improved the sustainability index by 0.32%. The findings demonstrate that Z-shaped fins improve the overall, exergy, and sustainability performances of air-cooled PV/T systems under the climatic conditions of Malatya, T & uuml;rkiye. This study highlights the critical role of fin geometry in enhancing PV/T system performance and contributes valuable insights for the design of more efficient and sustainable solar energy systems.Öğe Abdominal compartment syndrome due to distended rectal stump(Aves, 2007) Yilmaz, Mehmet; Isik, Burak; Ugras, Murat; Soeguetlue, Goekhan; Ara, Cengiz; Yilmaz, SezaiAbdominal compartment syndrome is a serious and life-threatening condition that requires early recognition and urgent decompressive laparotomy. This case report describes an abdominal compartment syndrome due to a distended rectal stump. The patient had a previous sigmoid resection with colostomy performed for sigmoid volvulus. As far as we know, this is the first report of abdominal compartment syndrome due to rectal stump. In such cases, high index of suspicion and early intervention affect the clinical course.Öğe Abdominopelvic Actinomycosis Associated With an Intrauterine Device and Presenting With a Rectal Mass and Hydronephrosis: A Troublesome Condition for the Clinician(Int College Of Surgeons, 2012) Yilmaz, Mehmet; Akbulut, Sami; Samdanci, Emine Turkmen; Yilmaz, SezaiActinomycosis is an uncommon, chronic, granulomatous disease that can be mistaken for a malignant tumor. Abdominopelvic actinomycosis constitutes about 20% of all actinomycosis cases and may mimic malignancy, tuberculosis, or other abdominopelvic inflammatory diseases. This condition is more prevalent in women who use an intrauterine device. We treated a 44-year-old woman who presented with vaginal discharge, right flank pain, dysuria, and difficulty with defecation. She had anorexia and weight loss (8 kg) during the previous 2 months and had a history of intrauterine device use for 12 years. Clinical, radiologic, and endoscopic examinations revealed a rectal mass and right hydronephrosis. Rectal biopsy showed nonspecific colitis. Laparotomy showed a mass that was invading and obstructing the pelvic orifice. Surgery included total abdominal hysterectomy, bilateral salpingo-oophorectomy, appendectomy, low anterior resection, and Hartmann colostomy. Histopathologic evaluation of surgical specimens showed actinomycosis originating from the tubo-ovarian structures and invading the rectal wall. The patient was placed on penicillin for 6 months, and then had closure of the colostomy with no complication.Öğe Abo-Incompatible Liver Transplantation in Acute and Acute-On-Chronic Liver Failure(H G E Update Medical Publishing S A, 2013) Yilmaz, Sezai; Aydin, Cemalettin; BurakIsik; Kayaalp, Cuneyt; Yilmaz, Mehmet; Ara, Cengiz; Kutlu, RamazanBackground/Aims: ABO-incompatible (ABO-I) liver transplantation (LTx) may be mandatory in urgent conditions such as acute liver failure (ALF) or acute-on-chronic liver failure (ACLF) when deceased donor (DD) is unavailable or living donor (LD) selection is limited. This study specifically addresses the problem of urgent ABO-I LTx in critically ill adult patients having ALF or severely decompensated end-stage liver disease. Methodology: This series included 16 patients, 10 underwent ABO-I LD LTx and 6 underwent 7 ABO-I DD LTx. Multiple sessions of plasmapheresis reduced isoaglutinin titres to 1/16 or below, before and after LTx. Results: Mean follow-up period was 10.37 months (1 to 38). Median for MELD scores was 22.5 (17 to 30). Median survival was 9 months and mean survival was 19.5 months. Hospital mortality was 3 (18.7%). Two patients died due to small for size graft syndrome and cerebrovascular bleeding respectively. Hepatic artery thrombosis developed in 3 patients. Two of them died at postoperative 4th and 9th months. Third patient is still alive with hepatic necrosis problem. Conclusions: ABO-I LTx remains an important and unavoidable therapeutic option in adult patients with ALF or ACLF and urgent need for an allograft without the possibility to allocate a blood group compatible liver graft.Öğe Aborted Donor Hepatectomies for Living Donor Liver Transplantation: A Single Center Experience(Lippincott Williams & Wilkins, 2016) Kutluturk, Koray; Otan, Emrah; Dirican, Abuzer; Yilmaz, Mehmet; Isik, Burak; Ozdemir, Fatih; Ince, Volkan[Abstract Not Available]Öğe Acute acalculous cholecystitis induced by aortic dissection: report of a case(Turkish Assoc Trauma Emergency Surgery, 2010) Sogutlu, Gokhan; Isik, Burak; Yilmaz, Mehmet; Karadag, Nese; Hoca, Onur; Olmez, Aydemir; Cinpolat, OezguerAcute acalculous cholecystitis (AAC), inflammation of the gallbladder without evidence of calculi, comprises approximately 10% of all cases of acute cholecystitis. Although the mechanism of AAC has not yet been sufficiently clarified, the most commonly postulated theories regarding its pathogenesis are bile stasis, sepsis and ischemia. We present a case of AAC associated with ischemia of the gallbladder caused by aortic dissection Bakey type III.Öğe Acute traumatic diaphragmatic ruptures: A retrospective study of 48 cases(Springer, 2011) Dirican, Abuzer; Yilmaz, Mehmet; Unal, Bulent; Piskin, Turgut; Ersan, Veysel; Yilmaz, SezaiPurpose. Traumatic diaphragmatic rupture (TDR) is associated with high rates of morbidity and mortality, and the preoperative diagnosis is difficult. Methods. Forty-eight patients with TDR were treated in our department between January 2000 and May 2009. The cause, location, size of rupture, associated morbidity and mortality, surgical material for repair, and predictive factors for overall outcome were evaluated. Results. There were 41 male patients (85%) and 7 female patients (15%) with a mean age of 33.8 years (range 17-69 years). Blunt trauma accounted for the injuries of 15 patients (31%) and 33 patients (68%) had penetrating injuries. The diagnosis was preoperatively established in 12 patients (25%) with a plain chest X-ray or/and computed tomography. The location of rupture was on the left side of the diaphragm in 35 patients (73%), on the right side in 10 (21%), and was bilateral in 3 patients (6%). Traumatic diaphragmatic rupture was repaired with interrupted nonabsorbable sutures or polypropylene mesh (8 patients). Postoperative complications were observed in 18 patients (38%). Overall mortality was observed in 7 patients (15%). The mortality was associated with hemorrhagic shock (P = 0.002), a high injury severity score (P = 0.002), and having additional injuries (P = 0.015). Conclusion. The outcome of the patients is associated with presence of hemorrhagic shock, a high injury severity score, and additional organ injury.Öğe Appendiceal Enterobius vermicularis infestation in adults(Int College Of Surgeons, 2007) Isik, Burak; Yilmaz, Mehmet; Karadag, Nese; Kahraman, Latif; Sogutlu, Gokhan; Yilmaz, Sezai; Kirimlioglu, VedatThe objective of this study is to evaluate the incidence of Enterobius vermicularis in the appendices of the adult population and a possible relationship between E. vermicularis and acute appendicitis. E. vermicularis was identified in 18 (2%) of 890 patients. Six hundred sixty-five operations were performed for presumptive diagnosis of acute appendicitis, and E. vermicularis was found in 12 (2%) patients. The histopathological examination revealed acute inflammatory cells in four cases (33%). Three of these four specimens included luminal ova and one E. vermicularis. Histopathological examination of six cases revealed E. vermicularis in 225 incidental appendectomies with no evidence of either acute or chronic inflammatory cells. This study suggests a relationship between the presence of E. vermicularis ova and acute inflammation, but the presence of the pinworm in the lumen of the appendix is coincidental. On the other hand E. vermicularis in the appendix lumen can cause symptoms of acute appendicitis.Öğe Auxiliary Reno-Portal Anastomosis in Living Donor Liver Transplantation: A Novel Technique for Recipients with Low Portal Inflow(Wiley-Blackwell, 2012) Akbulut, Sami; Kayaalp, Cuneyt; Yilmaz, Mehmet; Ozdemir, Fatih; Yilmaz, Sezai[Abstract Not Available]Öğe Auxiliary reno-portal anastomosis in living donor liver transplantation: a technique for recipients with low portal inflow(Wiley-Blackwell, 2012) Akbulut, Sami; Kayaalp, Cuneyt; Yilmaz, Mehmet; Yilmaz, Sezai[Abstract Not Available]Öğe Bilateral Lower Limb Edema Caused by Compression of the Retrohepatic Inferior Vena Cava by a Giant Hepatic Hemangioma(Int College Of Surgeons, 2013) Akbulut, Sami; Yilmaz, Mehmet; Kahraman, Aysegul; Yilmaz, SezaiHemangiomas are the most common benign primary tumors of the liver and their prevalence ranges from 0.4% to 20%. Approximately 85% of hemangiomas are clinically asymptomatic and are incidentally detected in imaging studies performed for other causes. In a very small minority of patients, nausea, vomiting, abdominal pain, distension, palpable mass, obstructive jaundice, bleeding, and signs and symptoms of Budd-Chiari syndrome may develop due to compression of bile duct, hepatic vein, portal vein, and adjacent organs. Occasionally, external compression of inferior vena cava may lead to edema and/ or indirect symptoms such as deep vein thrombosis of the lower limbs. In this report, we present a case of giant hepatic hemangioma that completely filled the right lobe of the liver. The patient presented with bilateral lower limb edema and pain. A computed tomography scan detected a 9 x 11 x 12 cm mass indicative of a hemangioma in the right lobe of the liver that compressed the inferior vena cava. The patient refused treatment initially but returned 6 months later presenting with the same symptoms. At that time, the mass had increased in size and a hepatectomy was performed, preserving the middle hepatic vein. By postoperative month 13, the swelling in the lower extremities had decreased significantly and the inferior vena cava appeared normal.Öğe Budd Chiari Syndrome Secondary to Compressive Effect of Giant Hydatid Cyst(Wiley-Blackwell, 2012) Yilmaz, Mehmet; Ozdemir, Fatih; Akbulut, Sami; Kahraman, Aysegul; Yilmaz, Sezai[Abstract Not Available]Öğe Budd-Chiari syndrome due to giant hydatid cyst: a case report and brief literature review(J Infection Developing Countries, 2013) Akbulut, Sami; Yilmaz, Mehmet; Kahraman, Aysegul; Yilmaz, SezaiBudd-Chiari syndrome is an uncommon disorder characterized by the thrombotic or non-thrombotic obstruction of hepatic venous outflow anywhere along the venous course from the hepatic venules to the junction of the inferior vena cava and the right atrium. The etiology of Budd-Chiari syndrome is classified as primary, attributable to intrinsic intraluminal thrombosis or the development of venous webs; or secondary, caused by intraluminal invasion by a parasite or malignant tumor or extraluminal compression by an abscess, solid tumor, or cyst, such as a hydatid cyst. In this study, we present a case of a giant hydatid cyst manifesting Budd-Chiari syndrome symptoms and signs by compressing the inferior vena cava and hepatic veins. In brief, the case demonstrates that hydatid disease should be considered in the differential diagnosis of Budd-Chiari Syndrome in areas such as Turkey, where hydatid disease is endemic.Öğe Chylous ascites after liver transplantation: Incidence and risk factors(Wiley-Blackwell, 2012) Yilmaz, Mehmet; Akbulut, Sami; Isik, Burak; Ara, Cengiz; Ozdemir, Fatih; Aydin, Cemalettin; Kayaalp, CuneytIn this study, we evaluated the diagnosis, epidemiology, risk factors, and treatment of chylous ascites developing after liver transplantation (LT). Between 2002 and 2011, LT was performed 693 times in 631 patients at our clinic. One-hundred fifteen of these patients were excluded for reasons such as retransplantation, early postoperative mortality, and insufficient data. Chylous ascites developed after LT (mean +/- SD = 8.0 +/- 3.2 days, range = 5-17 days) in 24 of the 516 patients included in this study. Using univariate and multivariate analyses, we examined whether the following were risk factors for developing chylous ascites: age, sex, body mass index, graft-to-recipient weight ratio, Model for End-Stage Liver Disease score, vena cava cross-clamping time, total operation time, Child-Pugh classification, sodium level, portal vein thrombosis or ascites before transplantation, donor type, albumin level, and perihepatic dissection technique [LigaSure vessel sealing system (LVSS) versus conventional suture ligation]. According to a univariate analysis, a low albumin level (P = 0.04), the presence of ascites before transplantation (P = 0.03), and the use of LVSS for perihepatic dissection (P < 0.01) were risk factors for developing chylous ascites. According to a multivariate Cox proportional hazards model, the presence of pretransplant ascites [P = 0.04, hazard ratio (HR) = 2.8, 95% confidence interval (CI) = 1.1-13.5] and the use of LVSS for perihepatic dissection (P = 0.01, HR = 5.4, 95% CI = 1.5-34.4) were independent risk factors. In conclusion, the presence of preoperative ascites and the use of LVSS for perihepatic dissection are independent risk factors for the formation of chylous ascites. To our knowledge, this study is the most extensive examination of the development of chylous ascites. Nevertheless, our results should be supported by new prospective trials. Liver Transpl, 2012. (C) 2012 AASLD.Öğe Circumferencial Fence of an Autologous Saphenous Vein Graft after Unification of Right Portal Vein Branches in Right Lobe, with Anomalous Portal Venous Branching, Living Donor Liver Transplantation; Malatya Approach(Wiley-Blackwell, 2011) Yilmaz, Sezai; Isik, Burak; Kutlu, Ramazan; Ozgor, Diner; Yilmaz, Mehmet; Ara, Cengiz; Dirican, Abuzer[Abstract Not Available]Öğe Clinical management, psychosocial characteristics, and quality of life in patients with homozygous familial hypercholesterolemia undergoing LDL-apheresis in Turkey: Results of a nationwide survey (A-HIT1 registry)(Elsevier Science Inc, 2019) Kayikcioglu, Meral; Kuman-Tuncel, Ozlem; Pirildar, Sebnem; Yilmaz, Mehmet; Kaynar, Leylagul; Aktan, Melih; Durms, Rana BerruBACKGROUND: Homozygous familial hypercholesterolemia (HoFH) is a rare, life-threatening inherited disease leading to early-onset atherosclerosis and associated morbidity. Because of its rarity, longitudinal data on the management of HoFH in the real world are lacking, particularly on the impact the condition has on quality of life (QoL), including the impact of the extracorporeal lipid removal procedure apheresis (LA). METHODS: The A-HIT1 study included 88 patients with HoFH aged >= 12 years receiving regular LA in 19 centers in Turkey. Demographic and disease characteristics data were obtained. For patients aged >= 18 years, additional data on psychosocial status were obtained via the SF-36 score, the Hospital Anxiety and Depression Scale, and a HoFH-specific questionnaire. RESULTS: There was no standardized approach to therapy between centers. Mean (+/-SD) frequency of LA sessions was every 19.9 (+/-14) days, with only 11.6% receiving LA weekly, and 85% of patients were not willing to increase LA frequency. The most common concerns of patients were disease prognosis (31%), and physical, aesthetic, and psychological problems (27.5%, 15.9%, and 11.6%, respectively). Lower age at diagnosis was associated with better QoL, lower anxiety, improved functioning, and greater emotional well-being compared to later diagnosis. CONCLUSIONS: These findings demonstrate that adult patients with HoFH undergoing LA, experience significant impairment of QoL with an increased risk of depression. From patients' point of view, LA is time-consuming, uncomfortable, and difficult to cope with. The speed of diagnosis and referral has a considerable impact on patient well-being. (C) 2019 National Lipid Association. All rights reserved.Öğe Coexistence of duodenum derived aggressive fibromatosis and paraduodenal hydatid cyst: A case report and review of literature(Baishideng Publishing Group Inc, 2018) Akbulut, Sami; Yilmaz, Mehmet; Alan, Saadet; Kolu, Mehmet; Karadag, NeseIntra-abdominal aggressive fibromatosis is a locally aggressive tumor mostly originating from the mesentery or retroperitoneal space, infiltrating adjacent tissues, and very rarely metastasizing to distant organs. There are only two case reports in the English language literature where intra-abdominal aggressive fibromatosis originated from the intestinal wall. In this study, we aimed to report a case of aggressive fibromatosis originating from the muscularis propria layer of the duodenum and invading pancreas. Another interesting aspect of this case is that a primary paraduodenal hydatid cyst was incidentally detected in the surgical specimen. A 46-year-old female patient presented to our clinic with postprandial nausea and vomiting. A contrast-enhanced abdominal computerized tomography revealed a mass lesion with a size of 100 mm x 80 mm which originated from the distal pancreas and compressed the gastric pilor externally. Upon exploration the distal part of duodenum, proximal jejunum, and pancreatic mass were noted to form a conglomerated structure. Therefore, the fourth part of the duodenum, a 25 cm part of the proximal jejunum, distal pancreas, and the spleen were excised en-bloc. The pathology report of the specimen indicated fibromatosis with a diameter of 55 mm that originated from the muscularis propria of the duodenum and extended into the pancreatic parenchyma. There was also an incidentally detected 10 mm paraduodenal hydatid cyst. No tumor recurrence was detected at a follow-up period of 24 mo. In conclusion, the most ideal treatment of desmoid-type fibromatosis is surgical resection of the mass lesion with clean surgical borders. Although rare, this tumor may originate from the intestinal wall. Histopathological verification is of great significance for a proper diagnosis.Öğe Coexistence of duodenum derived aggressive fibromatosis and paraduodenal hydatid cyst: a case report and review of literature(World journal of gastroıntestınal surgery, 2018) Akbulut, Sami; Yilmaz, Mehmet; Alan, Saadet; Kolu, Mehmet; Karadag, NeseIntra-abdominal aggressive fibromatosis is a locally aggressive tumor mostly originating from the mesentery or retroperitoneal space, infiltrating adjacent tissues, and very rarely metastasizing to distant organs. There are only two case reports in the English language literature where intra-abdominal aggressive fibromatosis originated from the intestinal wall. In this study, we aimed to report a case of aggressive fibromatosis originating from the muscularis propria layer of the duodenum and invading pancreas. Another interesting aspect of this case is that a primary paraduodenal hydatid cyst was incidentally detected in the surgical specimen. A 46-year-old female patient presented to our clinic with postprandial nausea and vomiting. A contrast-enhanced abdominal computerized tomography revealed a mass lesion with a size of 100 mm x 80 mm which originated from the distal pancreas and compressed the gastric pilor externally. Upon exploration the distal part of duodenum, proximal jejunum, and pancreatic mass were noted to form a conglomerated structure. Therefore, the fourth part of the duodenum, a 25 cm part of the proximal jejunum, distal pancreas, and the spleen were excised en-bloc. The pathology report of the specimen indicated fibromatosis with a diameter of 55 mm that originated from the muscularis propria of the duodenum and extended into the pancreatic parenchyma. There was also an incidentally detected 10 mm paraduodenal hydatid cyst. No tumor recurrence was detected at a follow-up period of 24 mo. In conclusion, the most ideal treatment of desmoid-type fibromatosis is surgical resection of the mass lesion with clean surgical borders. Although rare, this tumor may originate from the intestinal wall. Histopathological verification is of great significance for a proper diagnosis.Öğe COLON PERFORATION FOLLOWING CORONARYARTERY BYPASS GRAFTING(Istanbul Univ, Faculty Medicine, Publishing Office, 2006) Isik, Burak; Nisanoglu, Vedat; Yilmaz, Mehmet; Sogutlu, GokhanAlthough incidence of gastrointestinal complications following cardiac surgery is low, concomitant mortality is high. Intestinal ischemia is the most life-threatining one among these complications. In this paper, two cases of colon perforation, one of which with a mortal course, following coronary artery bypass grafting are presented. Delay with a concern of a negative laparotomy increases high mortality rate of ischemic intestinal complications rather than an early and curative procedure in a patient with a recent cardiac surgical procedure.Öğe Comparative and experimentally validated surrogate machine learning framework for predicting airflow velocity in EHD thrusters(Elsevier Science Inc, 2026) Toptas, Murat; Yilmaz, MehmetAccurate prediction of electrohydrodynamic (EHD) airflow is essential for advancing flow-control strategies, thermal management concepts, and low-power propulsion systems. In hybrid electric-magnetic EHD configurations, the induced flow field arises from a complex interaction among electric field gradients, charge transport, space-charge-driven momentum transfer, and Lorentz-force modulation. These nonlinear couplings are difficult for conventional analytical or numerical approaches to capture with sufficient fidelity. This study presents an experimentally validated and data-driven surrogate modeling framework for predicting airflow velocity in a multi-needle EHD thruster. A structured dataset was generated by systematically varying emitter voltage, emitter-collector spacing, and solenoid excitation. Four supervised regression models-Random Forest, Gradient Boosting, K-Nearest Neighbors, and ensemble-based techniques-were trained using standardized preprocessing and k-fold cross-validation. Among them, Gradient Boosting achieved the highest accuracy with an R2 of 0.8961, MAE of 0.0859, and MSE of 0.0115. To enhance physical interpretability, SHapley Additive exPlanations (SHAP) based analysis was performed. The results showed that emitter voltage dominates EHD-induced momentum transfer, while geometric spacing and magnetic forcing produce secondary modulation of the ion-driven flow. SHAP interactions further indicated that magnetic-field effects intensify at higher electric field strengths, aligning with expected multiphysics coupling mechanisms. Independent testing at previously unseen operating points confirmed strong agreement between predicted and measured velocities. The proposed framework provides a fast, transparent, and computationally efficient alternative to conventional simulations, offering new insight into coupled electro-fluidic behavior. Overall, the study demonstrates the potential of interpretable machinelearning-assisted modeling to accelerate the design and optimization of advanced thermo-fluidic and flowcontrol systems.
