Hydrogen Fuel Cell Powered Electric Vehicles And An Application Of Improvement For The Desorption Efficiency Of A Metal Hydride Storage

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2011Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2011İçinde bulunulan yüzyılda insanlarının en temel ihtiyaçlarından biri olan “ulaşım” yaygın olarak fosil yakıtlı araçlar tarafından karşılanmaktadır. Fosil yakıtların kıtlığı ve üretilmelerinden tüketilmelerine kadar olan çevrimde doğaya olan zararlı etkileri; alternatif, temiz enerji kaynaklarıyla (Ör: Güneş, Hidrojen) çalışan araçların gerekliliğini ortaya çıkarmaktadır. Bu çalışmada hidrojen yakıt hücreli elektrikli bir aracın, hidrojen saklama ortamının salıverme verimini arttırmak amaçlanmıştır. Aracın, polimer elektrolit membran tipli yakıt hücresi, hidrojen deposu olarak metal hidrid tüp grubu tarafından beslenmektedir. Araçta kullanılan metal hidrid saklama ortamlarının salıverme verimini arttırmak amacıyla kapalı devre ısı transfer sistemi kurulmuştur. Yapılan deneyler sonucunda kurulan sistemin, salınan hidrojen miktarını kayda değer oranda arttırdığı görülmüştür. Yakıt hücresi, çıkışında 800W güç üretecek şekilde yüklenmiş; ilk olarak ısı transfer sistemiyle, daha sonra ısı transfer sistemi olmadan, aynı şartlarda doldurulmuş metal hidrid tüpe bağlanmıştır. Isı transfer sistemi ile çalışan metal hidrid tüp 61 dakika boyunca; ısı transfer sistemi olmadan çalışan tüp ise sadece 18 dakika yakıt hücresini ortalama 800 W güç üretecek şekilde besleyebilmiştir.Fossil fuels are used by vehicles in transportation, which is one of the main needs of people. The share of transportation in fossil fuel usage is very high and daily oil consumption has been increasing. Shortage of fossil fuels and harmful effects’ have become main problem of today’s world. These causes force people to find new clean energy sources for vehicles to decrease pollutant gas emissions such as solar energy and hydrogen energy. In this study, it is aimed that improving the desorption efficiency of a hydrogen fuel cell vehicle’s hydrogen storage. The vehicle’s fuel cell type is PEM, which is sourced by a group of metal hydride hydrogen storage. To improve the desorption efficiency of the metal hydride storage; a closed-circuit heat transfer system was designed. The experiments showed that proposed system significantly increased the desorbed hydrogen amount from the metal hydride storage. The metal hydride storage was tested with and without proposed system while the PEM fuel cell was supplying 800 W output power. The storage could supply hydrogen for 61 minutes with proposed system, on the other hand; it could supply only 18 minutes without proposed system.Yüksek LisansM.Sc

Computed tomography-based morphometric measurements of the atlas (C1) posterior arc

Study design: Single-center retrospective study Objectives: This study is performed to determine the anatomic feasibility of the C1 posterior arc screw and help select an optimal screw trajectory in treating patients with craniovertebral junction pathologies. Material and Methods: We reported a single-centre retrospective study. Forty patients (20 male and 20 female) who underwent cervical computed tomography (CT) were chosen from the hospital records. Based on CT images, we measured left laminar length (LLL), right laminar length (RLL), left laminar angle (LLA), right laminar angle (RLA), left laminar axial thickness (LLAT), right laminar axial thickness (RLAT), left laminar coronal thickness (LLCT), right laminar coronal thickness (RLCT), and craniocaudal angle (CCA) of the C1 posterior arc. Results: The mean values and standard deviations (SD) for nine parameters at the C1 posterior arc were determined. LLL, RLL, LLCT, and RLCT were statistically longer in men than women. RLAT was bigger in men but there was no statistical difference. RLA was statistically wider in women than men. LLA and CCA were wider in women but there was no statistical difference, LLAT was bigger in women but there was no statistical difference. There was no statistical difference in measurements by age. Conclusion:  The results of this study are important to avoid neurovascular injury and pedicle breakage because of choosing large screw while performing C1 laminar screw fixation

Diffuse Hair Loss Induced by Sertraline Use

Hair loss is a rare side effect of psychotropic drugs. The most related drug class with this side effect is the mood stabilizers. Studies reporting the sertraline-induced alopecia are limited in number. Sertraline is a potent antidepressant which inhibits the serotonin reuptake from the presynaptic terminals selectively. The reason for hair loss could not be elucidated completely. Psychotropic drugs are usually considered to lead to hair loss through influencing the telogen phase of hair follicle. This paper reports a 21-year-old male with diffuse hair loss induced by sertraline use and improved by quitting the drug. To the best of our knowledge, there are no other case reports on sertraline-induced alopecia within 2 weeks

Azalmış ejeksiyon fraksiyonu olan kalp yetersizliği hastalarında anjiyotensin reseptörü neprilysin inhibitörü: Türkiye’den gerçek dünya deneyimi (ARNi-TR)

Objective: Heart failure (HF) is a growing public health problem with high morbidity and mortality. Recently, angio tensin receptor neprilysin inhibitor (ARNi) has emerged as a promising treatment for HF with reduced ejection fraction (HFrEF). Here, we shared our experience with the use of ARNi in HFrEF from multiple centers in Turkey.Methods: The ARNi-TR is a multicenter, nonintervention al, retrospective, observational study. Overall, 779 patients with HF from 22 centers in Turkey who were prescribed sacubitril/valsartan were examined. Initial clinical status, biochemical and echocardiographic parameters, and New York Heart Association functional class (NYHA-FC) values were compared with follow-up values after 1 year of ARNi use. In addition, the effect of ARNi on number of annual hospitalizations was investigated, and the patients were divided into 2 groups, depending on whether ARNi was ini tiated at hospitalization or under outpatient clinic control.Results: N-terminal pro-brain natriuretic peptide (NT-proB NP), left-ventricle ejection fraction (LV-EF), and NYHA-FC values improved significantly in both groups (all parame ters, p<0.001) within 1-year follow-up. In both groups, a de crease in hemoglobin A1c (HbA1c) values was observed in ARNi use (p<0.001), and a decrease in daily diuretic doses and hospitalizations owing to HF were observed after ARNi use (all comparisons, p<0.001). Hypotension (16.9%) was the most common side effect in patients using ARNi.Conclusion: The ARNi-TR study offers comprehensive re al-life data for patients using ARNi in Turkey. The use of ARNi has shown significant improvements in FC, NT-proB NP, HbA1c levels, and LV-EF. Likewise, reductions in the number of annual hospitalizations and daily furosemide doses for HF were seen in this study

Heart Failure Awareness Survey in a Turkish Population: HFAS-TR.

Objective: Heart failure is a leading cause of death and the most common diagnosis leading to hospitalization. Its awareness is lower than that of other cardiovascular diseases, both in the general population and among patients with heart failure (HF). This study aimed to establish the current level of knowledge about HF in patients with HF with reduced ejection fraction (HFrEF) and mildly reduced ejection fraction (HFmrEF) in Türkiye. Methods: This questionnaire-based survey study is multicenter, conducted across 34 centers from December 2021 to July 2022. We performed a survey consisting of two sets of questions focusing on individual characteristics of the patients and HF-related knowledge. Results: The study included a total of 2,307 outpatient HF patients, comprising 70.5% males and 29.5% females with a mean age of 64.58 ± 13 (56-74) years and a mean body mass index value of 32.5 ± 10 kg/m2. HFrEF and HFmrEF were determined in 74.7% and 25.3% of patients, respectively. Thirty percent of the patients were unaware that they had HF. While 28.7% of the patients thought that they had sufficient information about HF, 71.3% believed they lacked adequate knowledge. In the study, 25.2% of the participants identified dyspnea, 22% identified tiredness, and 25.4% identified leg edema as the most common symptoms of HF. Only 27.4% of patients recognized all three typical symptoms of HF. Conclusion: We found that the study population’s knowledge about HF symptoms and the nature of the disease was poor. Educational and awareness activities are necessary to optimize outcomes and benefits

Efficacy of subsequent treatments in patients with hormone-positive advanced breast cancer who had disease progression under CDK 4/6 inhibitor therapy.

Background There is no standard treatment recommended at category 1 level in international guidelines for subsequent therapy after cyclin-dependent kinase 4/6 inhibitor (CDK4/6) based therapy. We aimed to evaluate which subsequent treatment oncologists prefer in patients with disease progression under CDKi. In addition, we aimed to show the effectiveness of systemic treatments after CDKi and whether there is a survival difference between hormonal treatments (monotherapy vs. mTOR-based). Methods A total of 609 patients from 53 centers were included in the study. Progression-free-survivals (PFS) of subsequent treatments (chemotherapy (CT, n:434) or endocrine therapy (ET, n:175)) after CDKi were calculated. Patients were evaluated in three groups as those who received CDKi in first-line (group A, n:202), second-line (group B, n: 153) and >= 3rd-line (group C, n: 254). PFS was compared according to the use of ET and CT. In addition, ET was compared as monotherapy versus everolimus-based combination therapy. Results The median duration of CDKi in the ET arms of Group A, B, and C was 17.0, 11.0, and 8.5 months in respectively; it was 9.0, 7.0, and 5.0 months in the CT arm. Median PFS after CDKi was 9.5 (5.0-14.0) months in the ET arm of group A, and 5.3 (3.9-6.8) months in the CT arm (p = 0.073). It was 6.7 (5.8-7.7) months in the ET arm of group B, and 5.7 (4.6-6.7) months in the CT arm (p = 0.311). It was 5.3 (2.5-8.0) months in the ET arm of group C and 4.0 (3.5-4.6) months in the CT arm (p = 0.434). Patients who received ET after CDKi were compared as those who received everolimus-based combination therapy versus those who received monotherapy ET: the median PFS in group A, B, and C was 11.0 vs. 5.9 (p = 0.047), 6.7 vs. 5.0 (p = 0.164), 6.7 vs. 3.9 (p = 0.763) months. Conclusion Physicians preferred CT rather than ET in patients with early progression under CDKi. It has been shown that subsequent ET after CDKi can be as effective as CT. It was also observed that better PFS could be achieved with the subsequent everolimus-based treatments after first-line CDKi compared to monotherapy ET

Efficacy of Capecitabine and Temozolomide Regimen in Neuroendocrine Tumors: Data From the Turkish Oncology Group

INTRODUCTION: This study aims to report the efficacy and safety of capecitabine plus temozolomide (CAPTEM) across different lines of treatment in patients with metastatic neuroendocrine tumors (NETs). METHODS: We conducted a multicenter retrospective study analyzing the data of 308 patients with metastatic NETs treated with CAPTEM between 2010 and 2022 in 34 different hospitals across various regions of Turkey. RESULTS: The median follow-up time was 41.0 months (range: 1.7-212.1), and the median age was 53 years (range: 22-79). Our results across the entire patient cohort showed a median progression-free survival (PFS) of 10.6 months and a median overall survival (OS) of 60.4 months. First-line CAPTEM treatment appeared more effective, with a median PFS of 16.1 months and a median OS of 105.8 months (median PFS 16.1, 7.9, and 9.6 months in first-, second- and ≥third-line respectively, P = .01; with median OS values of 105.8, 47.2, and 24.1 months, respectively, P = .003) In terms of ORR, the first-line treatment again performed better, resulting in an ORR of 54.7% compared to 33.3% and 30.0% in the second and third or higher lines, respectively (P < .001). Grade 3-4 side effects occurred only in 22.5% of the patients, leading to a discontinuation rate of 9.5%. Despite the differences in outcomes based on treatment line, we did not observe a significant difference in terms of side effects between the first and subsequent lines of treatment. CONCLUSIONS AND RELEVANCE: The substantial superior outcomes in patients receiving first-line CAPTEM treatment highlight its potential as an effective treatment strategy for patients with metastatic NET