İstanbul Sağlık ve Teknoloji Üniversitesi Kurumsal Akademik Arşivi
DSpace@İSTÜN, Üniversite mensupları tarafından doğrudan ve dolaylı olarak yayınlanan; kitap, makale, tez, bildiri, rapor, araştırma verisi gibi tüm akademik kaynakları uluslararası standartlarda dijital ortamda depolar, Üniversitenin akademik performansını izlemeye aracılık eder, kaynakları uzun süreli saklar ve telif haklarına uygun olarak Açık Erişime sunar.
Güncel Gönderiler
Early fibrinogen replacement based on shock index and lactate levels in massive postpartum hemorrhage: A retrospective cohort study
(SIMTI, 2025) Küçükbaş, Mehmet; Güner Özen, Eda; Özen, Süleyman; Selçuk, Selçuk; Polat, Mesut; Karateke, Ateş
Background - Massive postpartum hemorrhage (PPH) remains a major cause of maternal morbidity and mortality worldwide. Timely fibrinogen replacement is critical in hemostatic resuscitation, yet laboratory delays may hinder early intervention. This study evaluates the clinical outcomes of early fibrinogen concentrate administration in massive PPH using a protocol based on shock index and serum lactate levels rather than laboratory-confirmed hypofibrinogenemia. Materials and methods - This retrospective cohort study included 103 PPH patients treated at a tertiary hospital in Istanbul, Turkey, between 2016 and 2020. Patients were divided into four groups based on fibrinogen dose: Group I (<2 g), Group II (2–4 g), Group III (>4 g), and Group IV (non-massive PPH, no fibrinogen). A predefined protocol guided early fibrinogen administration based on clinical indicators. Fibrinogen was administered without awaiting lab confirmation. Results - Group III had the highest estimated blood loss (2,600±500 mL) and Group IV the lowest (600±150 mL; p<0.001). ICU admission was significantly lower in Group III (23.8%) than in Group I (62.1%; p=0.020). Group III patients also had fewer secondary surgical interventions and reduced transfusion requirements compared to Groups I and II. No thromboembolic events or mortality were observed in any group. Discussion - Early fibrinogen replacement based on shock index and lactate levels appears feasible and beneficial in managing massive PPH. This approach was associated with improved hemostatic control, reduced ICU admissions, and fewer surgical interventions. Prospective studies are warranted to further assess this strategy’s safety, efficacy, and cost-effectiveness.
Comprehensive classification of variations of the anterior part of the circle of willis in fresh cadavers anterior communicating artery
(Galenos Publishing House, 2025) Nteli Chatzioglou, Gkionoul; Nas, Emine; Kale, Ayşin; Aktaş, Kardelen; Coşkun, Osman; Gayretli, Özcan
Objective: The goal of our study is to evaluate and classify the variations of the anterior communicating artery (AComA) on fresh cadavers from the Türkiye population. Methods: In this study, 182 fresh cadavers were analysed and classified according to the number, shape and course of the AcomA. Results: In our study, typical AcomA was the most common with a rate of 86 (47.25%), while variations of the AcomA were found in the remaining 96 (52.75%) cases. Among these variations, in 11.46% (11/96) of cases, AcomA variations were identified as distal and proximal duplications according to the number of branches they represented; 68.75% (66/96) of cases were identified by their shape (X-shaped, single/double fenestration, hypoplasia, or aplasia); and, in 19 cases, it was characterized by course (median artery or oblique course). The rate of variations was 65% (26/40) in females and 49.29% (70/142) in males. In our study, the X-shaped and single fenestration variations were recorded as the most common. Conclusions: The results of the study are important for cerebrovascular surgery and radiological interventions. It emphasises the importance of recognising and considering variations. The study will contribute to the understanding of cerebrovascular diseases and the development of treatment strategies.
Regülatör ağırlıklarının motor performansına etkisi
(Zenodo, 2025) Gündemin, Nevin; Aydoğdu, Ervanur; Tunçer, Erdal; Doğan, Battal
Dizel motorlar, yakıt dönüşüm verimlilikleri ve yüksek tork kapasiteleri sebebiyle farklı sektörlerde birincil güç kaynağı olarak tercih edilmektedir (Pachiannan ve diğ., 2025). İçten yanmalı motorlarda genellikle hidrokarbon içeren yakıt ile havanın yanması sonucunda enerji açığa çıkmaktadır (Görmez, 2020). Bu yanma olayı kumandalı (kontrollü) yanma, tutuşma gecikmesi ve ani yanma olarak 3 farklı aşama halinde ele alınmaktadır. Yanma aşamasının başlamasını sağlayan önemli parametrelerden biri ateşleme gecikmesidir (Miron ve diğ., 2021). Yakıtın püskürtülmeye başladığı zamandan silindir basıncının yüksek hızda arttığı zamana kadar geçen süreye ateşleme gecikmesi denilmektedir.
Motor püskürtme avansının motor performansına etkisi
(Zenodo, 2025) Uçkan, İrfan; Doğan, Battal; Tunçer, Erdal; Yılmaz, Gülten; Aydoğdu, Ervanur; Gündemin, Nevin
Sıkıştırma ateşlemeli motorların orta ve büyük araçlarda güç kaynağı olarak kullanılmasının sebepleri güç çıkışlarının, güvenilirliklerinin ve termal verimliliklerinin yüksek olmasıdır (Chen ve diğ., 2023). Sıkıştırma ateşlemeli bir motorda motor performansının, yanma safhalarının ve egzoz emisyonlarının oluşumunu etkileyen önemli parametrelerden birisi de ateşleme gecikmesinin süresidir (Kumar ve diğ., 2024). Enjeksiyonun başlamasıyla yanmanın başladığı zaman aralığı ateşleme gecikmesi olarak ifade edilmektedir. Enjektör iğnesinin yuvasından kalktığı noktadaki zaman genellikle enjektör başlangıcı olarak ele alınmaktadır. Yanmanın tam olarak nerede başladığını tespit edebilmek kolay değildir. Yanmanın başlangıcını tespit edebilmek için başvurulabilecek en iyi yöntem silindir basıncı için elde edilen verileri kullanarak krank açısına göre ısı yayma hızının eğimindeki değişimi gözlemlemektir (Kumar ve diğ., 2020).
Effects of blending linseed biodiesel into the fuel used in a single cylinder diesel engine
(Technical University of Gabrovo, 2024) Tunçer, Erdal; Kumkale, Murat Hüseyin; Akal, Dinçer; Tez, Taşkın; Umut, İlhan; Akı, Ozan
In many countries around the world, internal combustion engines are still used in transport and other sectors. The search for alternative fuels continues because the environmental damage caused by exhaust emissions increases with the length of time combustion engines are used. On the other hand, the depletion of oil resources and the increase in fuel prices are causing economic problems. In this study, 10% linseed biodiesel was blended with diesel fuel used in a single-cylinder internal combustion diesel engine, and its effects on the engine characteristics were investigated. According to the results obtained from the experiments, it was observed that linseed biodiesel added to diesel caused a slight increase in carbon monoxide, carbon dioxide, and hydrocarbon levels in exhaust emissions, while engine power and fuel consumption remained almost at the same level. It is expected that these results from the experiments will contribute to the evaluation of various studies on biodiesel in the future.
