104 results on '"Dimitrios, Nikas"'
Search Results
2. Experimental Investigations in the Processing of AISI H11 Powder Blends Enriched with Tungsten Carbide Nanoparticles for the Additive Manufacturing of Tailored Hot Working Tools in the Directed Energy Deposition (DED-LB/M)—Impact of Tungsten Carbide Nanoparticles on Microstructural and Mechanical Characteristics
- Author
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Oliver Hentschel, Jan Kohlstruck, Johannes Vetter, Alexander Wittmann, Pavel Krakhmalev, Dimitrios Nikas, and Michael Schmidt
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Directed Energy Deposition (DED-LB/M) ,Additive Manufacturing ,hot work tool steel ,AISI H11 ,Tungsten Carbide (WC) ,nanoparticles ,Mining engineering. Metallurgy ,TN1-997 - Abstract
In this study, the DED-LB/M process of AISI H11 tool steel powder blends modified by adding WC nanoparticles (WC-np) in concentrations of 1, 2.5 and 5 wt.-% was the object of scientific investigations. For this, 30-layer cuboid specimens were manufactured. The overall scientific aim was to examine how the WC-np interact with the steel melt and in the end, influence the processability, microstructure and mechanical properties of produced specimens. The examinations were carried out on both as-built and thermally post-processed specimens. An advanced microstructural analysis (SEM, EDS, EBSD and XRD) revealed that due to the high solubility of WC-np in the molten steel, most of the WC-np appear to have dissolved during the ongoing laser process. Furthermore, the WC-np favor a stronger distortion and finer grain size of martensite in the manufactured specimens. An increase in hardness from about 650 HV1 for the H11 specimen to 780 HV1 for the one manufactured using the powder blend containing 5 wt.-% of WC-np was observed in as-built conditions. In the same way, the compression yield strength enhanced from 1839 MPA to 2188 MPA. The hardness and strength increasing effect of WC-np remained unchanged even after heat treatments similar to those used in industry.
- Published
- 2024
- Full Text
- View/download PDF
3. Transcatheter Aortic Valve Implantation with the Portico Valve: 2-Year Outcomes of a Multicenter, Real-World Registry
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Matthaios Didagelos, Vlasis Ninios, Charalampos Kakderis, Lampros Lakkas, Antonios Kouparanis, Dimitrios Nikas, Katerina K. Naka, Aidonis Rammos, Thomas Zegkos, Vasileios Kamperidis, Ilias Ninios, Sotirios Evangelou, Dimitrios G. Tsalikakis, Lampros Michalis, and Antonios Ziakas
- Subjects
TAVI ,Portico ,aortic stenosis ,valvular disease ,Science - Abstract
Introduction: The self-expanding, resheathable, repositionable transcatheter aortic heart valve Portico is being used successfully for transcatheter aortic valve implantation procedures (TAVI) in patients with severe aortic stenosis. The aim of this study was to evaluate outcomes at 2 years after TAVI with the Portico valve. Methods: Multicenter registry of clinical, echocardiographic and survival data from consecutive patients treated with the Portico TAVI system (Abbott, Chicago, IL, USA) in three cath labs in Northern Greece and Epirus during 2017–2020. The primary end point was all-cause mortality at 24 months. Secondary end points included procedural outcomes (efficacy and safety) and echocardiographic measurements. Results: A total of 90 patients (81 ± 6 years, 50% females, mean age 81 ± 6 years) were included in the registry. The indication for implantation was severe, symptomatic aortic stenosis (NYHA III, IV) in eighty-two (91.1%) and degeneration of a prosthetic aortic valve in eight (8.9%) patients. All patients were categorized as high surgical risk (mean Logistic Euroscore 25.9 ± 10, Euroscore II 7.7 ± 4.4 and STS score 10.8 ± 8.9). The procedure was performed transfemorally in all patients, under general anesthesia in 95.6%, under TOE guidance in 21.1%, with native valve predilatation in 46.7%, and the “resheath” option was used in 31.1% of the cases. The implantation was successful in 97.8% and there was a need for a second valve in 2.2% of the cases. Complications included permanent pacemaker implantation (16.7%), access cite complications (15.6%), arrythmias (23.3%), paravalvular leak (moderate 7.8%, severe 1.1%), acute kidney injury (7.8%), no strokes and one death during the procedure. Aortic valve peak velocity, peak and mean pressure gradients, were significantly reduced after the procedure. All-cause mortality at 1, 12 and 24 months was 4.4%, 6.7% and 7.8%, respectively. Conclusions: TAVI with the Portico system comprises an effective and safe solution for the management of severe, symptomatic aortic stenosis in high-risk surgical patients.
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- 2023
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4. Duplication of the Artery to the Cystic Duct: A Case Report of a Rare Anatomical Variation with Surgical Significance
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Theodoros Mariolis-Sapsakos, Maria Zarokosta, Dimitrios Nikas, Aikaterini Foutsitzi, Stavros Angelis, George Noussios, and Dimitrios Filippou
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cystic duct ,anatomic variation ,cholecystectomy ,laparoscopic ,Medicine - Abstract
Anatomical variations of the cystic artery are frequently documented, but variations of the artery to the cystic duct are extremely uncommon. We report a rare duplication of the artery to the cystic duct, revealed during laparoscopic cholecystectomy on an 18-year-old Caucasian female treated for gallstone disease. Both arterial branches were meticulously and carefully retracted and cauterized to avoid bleeding and subsequent postoperative complications. To our knowledge, this is the first reported case of an artery to the cystic duct duplication. The presence of congenital variations of the artery to the cystic duct encumbers surgical maneuvers and increases the potentiality of intraoperative injury and hemorrhage.
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- 2022
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5. Experimental Investigations in the Processing of AISI H11 Powder Blends Enriched with Tungsten Carbide Nanoparticles for the Additive Manufacturing of Tailored Hot Working Tools in the Directed Energy Deposition (DED-LB/M)—Impact of Tungsten Carbide Nanoparticles on Microstructural and Mechanical Characteristics
- Author
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Hentschel, Oliver, Kohlstruck, Jan, Vetter, Johannes, Wittmann, Alexander, Krakhmalev, Pavel, Dimitrios, Nikas, Schmidt, Michael, Hentschel, Oliver, Kohlstruck, Jan, Vetter, Johannes, Wittmann, Alexander, Krakhmalev, Pavel, Dimitrios, Nikas, and Schmidt, Michael
- Abstract
In this study, the DED-LB/M process of AISI H11 tool steel powder blends modified by adding WC nanoparticles (WC-np) in concentrations of 1, 2.5 and 5 wt.-% was the object of scientific investigations. For this, 30-layer cuboid specimens were manufactured. The overall scientific aim was to examine how the WC-np interact with the steel melt and in the end, influence the processability, microstructure and mechanical properties of produced specimens. The examinations were carried out on both as-built and thermally post-processed specimens. An advanced microstructural analysis (SEM, EDS, EBSD and XRD) revealed that due to the high solubility of WC-np in the molten steel, most of the WC-np appear to have dissolved during the ongoing laser process. Furthermore, the WC-np favor a stronger distortion and finer grain size of martensite in the manufactured specimens. An increase in hardness from about 650 HV1 for the H11 specimen to 780 HV1 for the one manufactured using the powder blend containing 5 wt.-% of WC-np was observed in as-built conditions. In the same way, the compression yield strength enhanced from 1839 MPA to 2188 MPA. The hardness and strength increasing effect of WC-np remained unchanged even after heat treatments similar to those used in industry.
- Published
- 2024
- Full Text
- View/download PDF
6. Patients with Atrial Fibrillation and Chronic Kidney Disease More Often Undergo Angioplasty of Left Main Coronary Artery – a 867 Patient Study
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Anna Tomaszuk-Kazberuk, Dimitrios Nikas, Paulina Lopatowska, Elzbieta Młodawska, Jolanta Malyszko, Hanna Bachorzewska-Gajewska, Slawomir Dobrzycki, Bożena Sobkowicz, and Ioannis Goudevenos
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Atrial fibrillation ,Kidney function ,Estimated glomerular filtration rate ,Coronary artery disease ,Dermatology ,RL1-803 ,Diseases of the circulatory (Cardiovascular) system ,RC666-701 ,Diseases of the genitourinary system. Urology ,RC870-923 - Abstract
Background/Aims: Several studies have implicated atrial fibrillation (AF) as a contributing factor in chronic kidney disease (CKD) and cardiovascular events. The prevalence of coronary artery disease (CAD) in patients with AF varies substantially from 17% to 46.5%. There are only few studies concerning renal function in population with AF undergoing coronary angiography. The aim of the present study was to assess which type of AF is dominant in CKD population scheduled for coronary angiography and if it can influence patients’ outcome, the association between renal impairment and the type of coronary procedures in AF patients and the influence of renal function on in-hospital mortality. Methods: We retrospectively studied 867 patients with AF hospitalized due to coronary angiography in two year time. The cut off value of CKD was eGFR ≤ 60 ml/min./1.73m2 evaluated by CKD-EPI formula. Results: A total of 867 patients with AF (44% women; mean age 72±10 years) were included in the analysis. The mean eGFR was 44±11ml/min./1.73m2 in patients with CKD and 89±18 ml/min./1.73m2 in patients with preserved renal function. Patients with CKD and AF were older (p< 0.001), had more often diabetes (p=0.009), heart failure (p< 0.001) and anaemia (p< 0.001). Patients with CKD and AF had more often permanent type of AF (p< 0.001). In CKD patients CHA2DS2VASc score was 4.3±1.5 and HAS-BLED score was 2.0±1.2 and it was significantly higher as compared to population with preserved renal function (p< 0.001, p=0.02, respectively). The use of oral anticoagulation was less frequent in CKD group (p< 0.001) although these patients had higher CHA2DS2VASc score. Patients with AF and CKD were more often admitted due to myocardial infarction (STEMI or NSTEMI) (p=0.02, p< 0.001, respectively) and more often underwent percutaneous coronary intervention (PCI) (p=0.01). Among coronary arteries the percutaneous coronary intervention (PCI) of left main artery was done more frequently in CKD patients (p=0.01). Among CKD population in-hospital mortality was significantly higher in patients with eGFR < 30 ml/min (p< 0.001). Conclusion: Patients with CKD had more often permanent type of AF. Percutaneous interventions of the left main coronary artery, the only elective procedures influencing patients’ prognosis, were done more frequently in CKD patients with AF. In-hospital mortality was significantly higher in patients with severe renal impairment. Despite the higher risk of ischaemic stroke in CKD group the use of oral anticoagulation therapy was significantly less frequent and the patients were deprived of the confirmed benefits of such treatment.
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- 2018
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7. The TRACE registry (Trans-Radial Approach in Central and northErn Greece)
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Antonios Ziakas, Sotirios Katranas, Georgios Bobotis, Aggeliki-Despoina Mavrogianni, Christos Graidis, Nikolaos Mezilis, Αntonios Arampatzis, Dimitrios Nikas, Fotios Economou, Ilias Athanasiadis, Dimitrios Stakos, Vasilios Dimopoulos, Eugenia Pappa, Antonios Κouparanis, Dimitrios Petroglou, and Haralampos Karvounis
- Subjects
Trans-femoral approach ,Coronary angiography ,Percutaneous coronary intervention ,Financial crisis ,Diseases of the circulatory (Cardiovascular) system ,RC666-701 - Abstract
Objective: We examined trans-radial approach (TRA) use in coronary angiographies (CAs) as well as in percutaneous coronary interventions (PCIs) in specific regions of Greece, its distribution in public and private catheterization laboratories (CLs) and its preference by operators. Reliable data regarding the use of TRA are not available in Greece. Methods: The study was performed in northern and central Greece, which constitutes 35.32% of the national population. This study focused on the years 2004, 2009 and 2013. Results: There are 12 CLs. CAs performed using TRA were 0.43% in 2004, 12.28% in 2009 and 39.81% in 2013, whereas PCIs performed using TRA were 0.38%, 9.20% and 39.48%, respectively. Operators familiar with TRA, but who performed TRA electively, were 13.33% in 2004, 60.38% in 2009 and 42.37% in 2013. However, operators performing TRA routinely were 2.2%, 5.66%, and 49.15%, respectively. In 2013, there was a 3.76% decrease in CAs and 4.51% decrease in PCIs compared to 2009; in private CLs, there was a 29.63% decrease in CAs and 34.72% decrease in PCIs performed, which was contradictory to the 27.27% increase observed in CAs and 29.83% increase in PCIs in public CLs. Conclusions: This is the first study to reveal the volumes and trends in interventions performed via TRA across central and northern Greece. TRA has gained a reputation among operators in both public and private CLs. Due to the financial crisis in Greece, catheterizations have been diminished, whereas private CLs have lost a great amount of their turnover.
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- 2016
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8. Extracalvarial Composite Infantile Myofibromatosis: Case Report and Literature Review
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Alexander Ivanov, Tibor Valyi-Nagy, and Dimitrios Nikas
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infantile myofibromatosis ,composite infantile myofibromatosis ,infantile fibrosarcoma ,Pediatrics ,RJ1-570 ,Surgery ,RD1-811 - Abstract
Abstract Infantile soft tissue tumors of the head are very rare and the majority of them are myofibromas. The authors present the case of a 1-day-old boy with a scalp tumor with several distinct histopathological features including myofibroma, hemangiopericytoma, and fibrosarcoma consistent with the diagnosis of composite infantile myofibromatosis. Genetic testing was negative for trisomy 17, translocation (12; 15), FUS, and ETV6 translocations. Despite the ominous histopathological features, the clinical course was benign. The authors review here available literature concerning current concepts of making the diagnosis of composite infantile myofibromatosis and discuss treatment options.
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- 2016
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9. A groove crossing the aortic root
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Dimitrios Nikas, Konstantinos V Stamatis, Angelos A Arseniou, Konstantinos Pappas, and Dimitrios Sfairopoulos
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business.industry ,Coronary Vessel Anomalies ,Aortic root ,Humans ,Medicine ,Anatomy ,Cardiology and Cardiovascular Medicine ,business ,Groove (joinery) ,Aorta - Published
- 2022
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10. Modelling of temperature and strain rate dependent behaviour of pearlitic steel in block braked railway wheels
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Dimitrios Nikas, Ali Esmaeili, Magnus Ekh, Johan Ahlström, and Tore V Vernersson
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Vehicle Engineering ,Materials science ,Pearlitic steel ,Computational Mechanics ,Transportation ,High temperatures ,Maskinteknik ,Materialteknik ,Other Materials Engineering ,Electrical and Electronic Engineering ,Composite material ,Railway wheels ,Mechanical load ,Applied Mechanics ,Viscoplasticity ,Tension (physics) ,Mechanical Engineering ,Torsion (mechanics) ,Materials Engineering ,Strain rate ,Compression (physics) ,Computer Science Applications ,Block braking ,Creep ,Hardening (metallurgy) - Abstract
Block braked railway wheels are subjected to thermal and rolling contact loading. The thermal loading results in high temperatures and thermal stresses which cause slow time dependent processes such as creep, relaxation and static recovery of the wheel material. At the same time, the rolling contact loading implies a very fast mechanical load application. This paper is focused on material modeling of pearlitic steel for a wide range of loading rates at elevated temperatures. The starting point is a viscoplasticity model including nonlinear isotropic and kinematic hardening. The Delobelle overstress function is employed to capture strain rate dependent response of the material. The model also includes static recovery of the hardening to capture slower viscous (diffusion dominated) behaviour of the material. Experiments for the pearlitic wheel steel ER7 in terms of cyclic strain-controlled uniaxial tests with hold-time, uniaxial ratchetting tests including rapid cycles and biaxial cyclic tests with tension/compression and torsion are used to calibrate the material model. These experiments were performed under isothermal conditions at different temperatures. In the ratchetting tests, higher loading rates are obtained and these have been used to calibrate the high strain rate response of the viscoplasticity model. The paper is concluded with a numerical example of a block braked wheel where the importance of accounting for the viscoplasticity in modelling is highlighted.
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- 2021
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11. Access-site Complications of the Transradial Approach: Rare But Still There
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Dimitrios Petroglou, Theofilos M. Kolettis, Stelina Alkagiet, and Dimitrios Nikas
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Male ,0301 basic medicine ,Cardiac Catheterization ,medicine.medical_specialty ,Radial artery puncture ,Fistula ,Perforation (oil well) ,Ischemia ,03 medical and health sciences ,Pseudoaneurysm ,0302 clinical medicine ,medicine.artery ,Occlusion ,medicine ,Humans ,Radial artery ,business.industry ,General Medicine ,Nerve injury ,medicine.disease ,Surgery ,030104 developmental biology ,030220 oncology & carcinogenesis ,Radial Artery ,Female ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,business - Abstract
In the past decade, the Transradial Approach (TRA) has constantly gained ground among interventional cardiologists. TRA’s anatomical advantages, in addition to patients’ acceptance and financial benefits, due to rapid patient mobilization and shorter hospital stay, made it the default approach in most catheterization laboratories. Access-site complications of TRA are rare and usually of little clinical impact, thus, they are often overlooked and underdiagnosed. Radial Artery Occlusion (RAO) is the most common, followed by radial artery spasm, perforation, hemorrhagic complications, pseudoaneurysm, arterio-venous fistula, and even rarer complications, such as nerve injury, sterile granuloma, eversion endarterectomy or skin necrosis. Most of them are conservatively treated, but rarely, surgical treatment may be needed and late diagnosis may lead to life-threatening situations, such as hand ischemia or compartment syndrome and tissue loss. Additionally, some complications may eventually lead to TRA failure and switch to a different approach. On the other hand, it is the opinion of the authors that non-occlusive radial artery injury, commonly included in TRA’s complications in the literature, should be regarded more as an anticipated functional and anatomical cascade, following radial artery puncture and sheath insertion.
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- 2021
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12. TME resections for rectal cancer: Results and survival
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Theodoros Piperos, Christos Sioros, Alexandros Manthas, Alexandra Varlatzidou, Eirini Nomikou, Savvas Tanteles, Dimitrios Nikas, Maria Zarokosta, Kontantinos Laschos, and Theodoros Mariolis-Sapsakos
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Oncology ,Surgery ,General Medicine - Published
- 2023
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13. Management of Asymptomatic Carotid Stenosis. an Issue with Unresolved Queries that Need Disambiguation
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Georgios I. Karaolanis MD, Dimitrios Nikas, Zachary F. Williams, Efstratios Georgakarakos, and Demetrios Moris
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- 2022
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14. Expert consensus statement for the management of patients with embolic stroke of undetermined source and patent foramen ovale: A clinical guide by the working group for stroke of the Hellenic Society of Cardiology and the Hellenic Stroke Organization
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Dimitrios Tziakas, Sofia Vassilopoulou, Konstantinos Spengos, Konstantinos Papadopoulos, Haralampos Milionis, Ioannis Kanakakis, Skevos Sideris, Konstantinos Toutouzas, Dimitrios Nikas, Konstantinos Tsioufis, Georgios Katsimagklis, Konstantinos Vemmos, Apostolos Tzikas, Antonis S. Manolis, Georgios Ntaios, Eleni Koroboki, and Emmanouil Vavouranakis
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Embolic Stroke ,medicine.medical_specialty ,Consensus ,Statement (logic) ,business.industry ,General surgery ,Cardiology ,MEDLINE ,Foramen Ovale, Patent ,Expert consensus ,medicine.disease ,Embolic stroke ,Stroke ,medicine ,Patent foramen ovale ,Humans ,Cardiology and Cardiovascular Medicine ,business - Published
- 2020
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15. Transient myocardial ischemia due to corticosteroid use in a patient with multiple sclerosis diagnosed with myocardial perfusion imaging
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Dimitris-Nikiforos Kiortsis, Dimitrios Nikas, Afroditi Tsoumani, Andreas Fotopoulos, Chrissa Sioka, and Vasiliki Kostadima
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medicine.medical_specialty ,Multiple Sclerosis ,medicine.diagnostic_test ,business.industry ,Multiple sclerosis ,Transient myocardial ischemia ,Myocardial Ischemia ,Myocardial Perfusion Imaging ,MEDLINE ,Middle Aged ,Coronary Angiography ,medicine.disease ,Methylprednisolone ,Myocardial perfusion imaging ,Internal medicine ,Cardiology ,Humans ,Medicine ,Female ,Radiology, Nuclear Medicine and imaging ,Corticosteroid use ,Cardiology and Cardiovascular Medicine ,business ,Glucocorticoids - Published
- 2020
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16. Stress relief during annealing of railway wheel steel characterized by synchrotron X-ray micro-diffraction
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Zhang, Yubin, Jessop, Casey, Dimitrios, Nikas, Yu, Tianbo, Liu, Wenjun, Ahlstrom, Johan, Zhang, Yubin, Jessop, Casey, Dimitrios, Nikas, Yu, Tianbo, Liu, Wenjun, and Ahlstrom, Johan
- Abstract
Railway wheels in service experience rolling contact fatigue loading, but also need to resist frictional heating on braking, yielding temperatures up to 500 degrees C. The combination of mechanical and thermal loads leads to changes in the mechanical properties of the material. The focus of this study is to investigate the effect of annealing on local microstructure and residual stresses in railway wheel pearlitic steel (medium carbon steels, similar to 0.55 wt.% C) using synchroton X-ray Laue micro-diffraction. It is found that the local residual stress releases to a large extent after annealing at 500 degrees C. The stress formation and relief mechanisms and their relationship to the local microstructure are discussed.
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- 2022
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17. Effect of annealing on microstructure in railway wheel steel
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Dimitrios, Nikas, Zhang, Yubin, Ahlstrom, Johan, Dimitrios, Nikas, Zhang, Yubin, and Ahlstrom, Johan
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Railway wheels are commonly made from medium carbon steels (similar to 0.55 wt.% C), heat treated to a near pearlitic microstructure with 5-10% pro-eutectoid ferrite. During the operation of freight trains, where block brakes are used, high thermal loads occur together with the high contact stresses, which combined can affect the mechanical properties of the material. In this study, the effects of annealing on local microstructure and mechanical properties in pearlitic railway wheel steel were investigated using electron microscopy and micro-hardness. It is found that after annealing at 650 degrees C, the room temperature hardness reduces about 25%, accompanied by significant spheroidization of cementite in the pearlitic colonies, though the size and the orientation gradients of the pearlitic colonies have not changed much. The relationship between the microstructural changes and the mechanical properties are discussed.
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- 2022
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18. Effect of annealing on microstructure in railway wheel steel
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Dimitrios Nikas, Yubin Zhang, and Johan Ahlström
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Materialteknik ,General Medicine ,Materials Engineering - Abstract
Railway wheels are commonly made from medium carbon steels (~0.55 wt.% C), heat treated to a near pearlitic microstructure with 5–10% pro-eutectoid ferrite. During the operation of freight trains, where block brakes are used, high thermal loads occur together with the high contact stresses, which combined can affect the mechanical properties of the material. In this study, the effects of annealing on local microstructure and mechanical properties in pearlitic railway wheel steel were investigated using electron microscopy and micro-hardness. It is found that after annealing at 650 °C, the room temperature hardness reduces about 25%, accompanied by significant spheroidization of cementite in the pearlitic colonies, though the size and the orientation gradients of the pearlitic colonies have not changed much. The relationship between the microstructural changes and the mechanical properties are discussed.
- Published
- 2022
- Full Text
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19. 3D printing in adult and pediatric neurosurgery: the present and the future
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Dimitrios Nikas, Laura Stone McGuire, Keyoumars Ashkan, and Stavros Polyzoidis
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medicine.medical_specialty ,business.industry ,Pediatric neurosurgery ,Medicine ,Medical physics ,business - Published
- 2022
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20. Extended resections for anal cancer - Complex interventions
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Theodoros Piperos, Alexandros Manthas, Alexandra Varlatzidou, Dimitrios Nikas, Christos Sioros, Eirini Nomikou, Savvas Tanteles, Archodoula Xifara, and Theodoros Mariolis-Sapsakos
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Oncology ,Surgery ,General Medicine - Published
- 2023
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21. The COVID-19 Pandemic and Its Effects on the Greek Tourism Sector: A Case Study of the Region of Eastern Macedonia - Thrace
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Dimitrios Nikas, Anastasios G. Karasavvoglou, Ioannis Tsoukalidis, Georgia Vouloutidou, and Antonios Kostas
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Product (business) ,Coronavirus disease 2019 (COVID-19) ,Economy ,business.industry ,Political science ,Pandemic ,Health care ,Food service ,business ,Tourism - Abstract
The recent novel coronavirus pandemic (COVID-19 pandemic) has led to a new, multi-faceted societal, healthcare and generalized economic crisis, both at national and international levels. The measures taken to deal with the pandemic have resulted in unprecedented situations in almost all sectors of the Greek economy. This article attempted to investigate the extent of the impact of this new crisis on Greek tourism companies, focusing on the case of tourist accommodation and food services by region, since the tourism industry has been greatly afflicted. The main variable examined was the degree of decline in the turnover of the tourism businesses under discussion over the last two years, at regional and national levels. This was supplemented with comparative analyses of similar measurable data. Secondary and statistical data were obtained from the Hellenic Statistical Authority, the Hellenic Tourism Organization and databases of other related institutions. Keywords: COVID-19, tourism industry, Greek companies, tourist product, region οf Eastern Macedonia - Thrace
- Published
- 2021
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22. Autonomic Responses during Labor: Potential Implications for Takotsubo Syndrome
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Konstantinos C. Zekios, Orestis Tsonis, Minas Paschopoulos, Theoxaris I. Evaggelou, Errikos K. Moulias, Georgios E. Papadopoulos, Petros Tzimas, Dimitrios Nikas, and Theofilos M. Kolettis
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Takotsubo syndrome ,business.industry ,Vaginal delivery ,sympathetic responses ,vagal responses ,Pathophysiology ,Article ,Oxytocin ,cesarean delivery ,Anesthesia ,RC666-701 ,Medicine ,Diseases of the circulatory (Cardiovascular) system ,Pharmacology (medical) ,General Pharmacology, Toxicology and Pharmaceutics ,Cesarean delivery ,vaginal delivery ,business ,Complication ,medicine.drug - Abstract
Takotsubo syndrome is a serious complication of labor. Although the pathophysiologic role of excessive sympathetic activation is established in this process, concurrent vagal responses have not been adequately described. Moreover, it remains unclear whether autonomic activity depends on the mode of delivery. Here, we explored the hypothesis that the different management of cesarean and vaginal delivery may elicit diverse responses affecting both autonomic arms. For this aim, continuous electrocardiographic recording was performed in 20 women during labor, and non-invasive indices of sympathetic and vagal activity were compared between the two modes of delivery. We report sympathetic prevalence during cesarean delivery, caused by marked vagal withdrawal, whereas autonomic activity was rather stable during vaginal delivery. These differences may be attributed to the effects of anesthesia during cesarean delivery, along with the protective effects of oxytocin administration during vaginal delivery. Our results provide further insights on autonomic responses during labor that may prove useful in the prevention of complications, such as takotsubo syndrome.
- Published
- 2021
23. High Tolerability of Pitavastatin Therapy: A Case Report of Comparison with other Statins
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Georgios A Christou, Maria A Christou, Konstantinos A Christou, Dimitrios N. Kiortsis, Spyridon G Mprikos, Dimitrios Nikas, and Evangelos A A Christou
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myalgia ,medicine.medical_specialty ,business.industry ,Atorvastatin ,nutritional and metabolic diseases ,030209 endocrinology & metabolism ,030229 sport sciences ,medicine.disease ,Gastroenterology ,03 medical and health sciences ,0302 clinical medicine ,Tolerability ,Ezetimibe ,Internal medicine ,medicine ,lipids (amino acids, peptides, and proteins) ,Pharmacology (medical) ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,Pitavastatin ,business ,Dyslipidemia ,Pravastatin ,medicine.drug ,Fluvastatin - Abstract
Introduction: Myopathy is possibly the most clinically relevant statin-induced side effect. Case Presentation: We report a case of a 63-year-old healthy male with mixed dyslipidemia. He developed bilateral myalgia of the forearms with fluvastatin 40 mg/day, pravastatin 20 mg/day, and combination of atorvastatin 10 mg and ezetimibe 10 mg/day. The only hypolipidemic treatment that was tolerable was the combination of pitavastatin 1 mg and ezetimibe 10 mg/day. Discussion: Pitavastatin demonstrated less potential for the development of myalgia compared to the so far considered most tolerable statins (i.e., fluvastatin and pravastatin). All the tested statins were used at the lowest approved dose for clinical use. Conclusion: The combination of pitavastatin 1 mg and ezetimibe appears to be a promising treatment choice for individuals who are intolerant to statin therapy due to muscle complaints.
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- 2020
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24. Sympathetic Activation and Arrhythmogenesis after Myocardial Infarction: Where Do We Stand?
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Theofilos M. Kolettis, Eleni-Taxiarchia Mouchtouri, Panagiotis Lekkas, Konstantinos C. Zekios, and Dimitrios Nikas
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sympathetic activation ,medicine.medical_specialty ,Aldosterone inhibitor ,business.industry ,Infarction ,Review ,medicine.disease ,Neuromodulation (medicine) ,Sacubitril ,medicine.anatomical_structure ,myocardial infarction ,Renal sympathetic denervation ,Internal medicine ,Stellate ganglion ,Heart failure ,RC666-701 ,medicine ,Cardiology ,Diseases of the circulatory (Cardiovascular) system ,Pharmacology (medical) ,Myocardial infarction ,General Pharmacology, Toxicology and Pharmaceutics ,ventricular tachyarrhythmias ,business ,medicine.drug - Abstract
Myocardial infarction often leads to progressive structural and electrophysiologic remodeling of the left ventricle. Despite the widespread use of β-adrenergic blockade and implantable defibrillators, morbidity and mortality from chronic-phase ventricular tachyarrhythmias remains high, calling for further investigation on the underlying pathophysiology. Histological and functional studies have demonstrated extensive alterations of sympathetic nerve endings at the peri-infarct area and flow-innervation mismatches that create a highly arrhythmogenic milieu. Such accumulated evidence, along with the previously well-documented autonomic dysfunction as an important contributing factor, has stirred intense research interest for pharmacologic and non-pharmacologic neuromodulation in post-infarction heart failure. In this regard, aldosterone inhibitors, sacubitril/valsartan and sodium-glucose cotransporter type 2 inhibitors have shown antiarrhythmic effects. Non-pharmacologic modalities, currently tested in pre-clinical and clinical trials, include transcutaneous vagal stimulation, stellate ganglion modulation and renal sympathetic denervation. In this review, we provide insights on the pathophysiology of ventricular arrhythmogenesis post-myocardial infarction, focusing on sympathetic activation.
- Published
- 2021
25. Should Deferred Stenting Still Be Considered in ST-Elevation Myocardial Infarction with High Thrombus Burden?
- Author
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Konstantinos V Stamatis, Theofilos M. Kolettis, Spyridon D Pappas, Georgios I Katsanos, Xenofon M Sakellariou, Dimitrios Nikas, Andreas P Efstathopoulos, and Dimitrios Sfairopoulos
- Subjects
medicine.medical_specialty ,medicine.medical_treatment ,acute myocardial infarction ,030204 cardiovascular system & hematology ,03 medical and health sciences ,0302 clinical medicine ,high thrombus burden ,Internal medicine ,medicine ,Diseases of the circulatory (Cardiovascular) system ,Pharmacology (medical) ,030212 general & internal medicine ,Myocardial infarction ,Embolization ,cardiovascular diseases ,General Pharmacology, Toxicology and Pharmaceutics ,Thrombus ,stent implantation ,business.industry ,Communication ,Percutaneous coronary intervention ,Tirofiban ,medicine.disease ,primary percutaneous coronary intervention ,medicine.anatomical_structure ,surgical procedures, operative ,Thrombus burden ,micro-vascular obstruction ,RC666-701 ,Conventional PCI ,Cardiology ,business ,medicine.drug ,Artery ,deferred-stenting - Abstract
Patients with ST-elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI) may demonstrate distal microvascular embolization of thrombotic materials. We retrospectively examined 20 cases displaying extensive thrombus in the infarct-related artery (IRA), treated either with a two-step procedure, with interim tirofiban infusion, or immediate stent implantation. Distal embolization tended to be more common in the latter strategy, but, overall, the outcome was comparable. Thus, a two-staged procedure may be considered in selected cases of primary PCI associated with high thrombus burden.
- Published
- 2021
26. Stress relief during annealing of railway wheel steel characterized by synchrotron X-ray micro-diffraction
- Author
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Yubin Zhang, Casey Jessop, Dimitrios Nikas, Tianbo Yu, Wenjun Liu, and Johan Ahlström
- Subjects
Applied Mechanics ,Teknisk mekanik ,General Medicine - Abstract
Railway wheels in service experience rolling contact fatigue loading, but also need to resist frictional heating on braking, yielding temperatures up to 500 °C. The combination of mechanical and thermal loads leads to changes in the mechanical properties of the material. The focus of this study is to investigate the effect of annealing on local microstructure and residual stresses in railway wheel pearlitic steel (medium carbon steels, ~0.55 wt.% C) using synchroton X-ray Laue micro-diffraction. It is found that the local residual stress releases to a large extent after annealing at 500 °C. The stress formation and relief mechanisms and their relationship to the local microstructure are discussed.
- Published
- 2022
- Full Text
- View/download PDF
27. Interdisciplinary management of acute ischaemic stroke current evidence on training requirements for endovascular stroke treatment. Position Paper from the ESC Council on Stroke and the European Association for Percutaneous Cardiovascular Interventions with the support of the European Board of Neurointervention : a step forward
- Author
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Piotr Musialek, Ivo Petrov, Horst Sievert, Klaus Mathias, Zoltán Ruzsa, L. Nelson Hopkins, Maria Politi, Dimitrios Nikas, Rafał Niżankowski, Carlos Alejandro Alvarez, Iris Q Grunwald, Anna Luisa Kühn, Panagiotis Papanagiotou, Antonio Micari, and Sanjay Pillai
- Subjects
medicine.medical_specialty ,business.industry ,Vascular disease ,Universal design ,cerebral resuscitation ,Psychological intervention ,unmet needs ,multispecialty team ,Evidence-based medicine ,medicine.disease ,Invited Special Review ,mechanical thrombectomy ,Quality of life (healthcare) ,cardiology cathlab-based treatment ,Medicine ,Position paper ,cardiovascular diseases ,Cardiology and Cardiovascular Medicine ,business ,Intensive care medicine ,Stroke ,acute ischaemic stroke ,Cause of death - Abstract
Stroke, a vascular disease of the brain, is the #1 cause of disability and a major cause of death worldwide. Stroke has a major negative impact on the life of stroke-affected individuals, their families and the society. A significant proportion of stroke victims indicate that would have preferred death over their after-stroke quality of life. Mechanical thrombectomy (MT), opening the occluded artery using mechanical aspiration or a thrombus-entrapment device, is a guideline-mandated (class I, level of evidence A) treatment modality in patients with large vessel occlusion stroke. MT clinical benefit magnitude indicates that a universal access to this treatment strategy should be the standard of care. Today there is a substantial geographic variation in MT deliverability, with large-scale disparities in MT implementation. In many countries effective access to MT remains severely limited. In addition, many of the MT-treated patients are treated too late for a good functional outcome because of logistic delays that include transportations to remotely located, scarce, comprehensive stroke centres. Position Paper from the European Society of Cardiology Council on Stroke and European Association for Percutaneous Cardiovascular Interventions on interdisciplinary management of acute ischaemic stroke, developed with the support of the European Board of Neurointervention fills an important gap in systematically enabling interventional cardiologists to support stroke intervention in the geographic areas of unmet needs in particular. We review strengths and weaknesses of the document, and suggest directions for the next steps that are swiftly needed to deliver MT to stroke patients more effectively.
- Published
- 2021
28. Treatment of Mobile Right Heart Thrombi
- Author
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Andreas P Efstathopoulos, Xenofon M Sakellariou, Dimitrios Nikas, Theofilos M. Kolettis, and Konstantinos V Stamatis
- Subjects
medicine.medical_specialty ,pulmonary embolism ,medicine.medical_treatment ,lcsh:Medicine ,030204 cardiovascular system & hematology ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,Internal Medicine ,medicine ,cardiovascular diseases ,Thrombus ,half-dose alteplase ,business.industry ,lcsh:R ,030208 emergency & critical care medicine ,Articles ,Thrombolysis ,mobile right heart thrombi ,medicine.disease ,Right pulmonary artery ,Pulmonary embolism ,Embolism ,Thrombus burden ,Right heart ,Cardiology ,business - Abstract
Right heart thrombi are detected in approximately 4% of patients with pulmonary embolism. The associated mortality is high, but the optimal strategy remains controversial. We report a case of a large mobile right heart thrombus, complicated by embolism of the right pulmonary artery, which was successfully treated with half-dose alteplase. We briefly review the literature and discuss the therapeutic options, focusing on the advantages of thrombolysis. LEARNING POINTS Mobile right heart thrombi require rapid therapeutic choices between surgical thrombectomy and thrombolysis. Half-dose alteplase may be effective, even in the presence of an extensive thrombus burden.
- Published
- 2020
29. Tethered Cord Syndrome in the United States Cluster Analysis of Presenting Anomalies and Associated
- Author
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Samantha, Horn, Michael, Moses, Dennis, Vasquez-Montes, Aaron, Hockley, Gregory, Poorman, Cole, Bortz, Frank, Segreto, Avery, Brown, Katherine, Pierce, Haddy, Alas, Yael, Ihejirika, John, Moon, Christopher, Varlotta, David, Ge, Shaleen, Vira, Bassel, Diebo, Rafael, De la Garza Ramos, Renaud, Lafage, Virginie, Lafage, Daniel, Sciubba, Micheal, Raad, Dimitrios, Nikas, and Peter, Passias
- Subjects
Heart Defects, Congenital ,Inpatients ,Urogenital Abnormalities ,Cluster Analysis ,Humans ,Abnormalities, Multiple ,Neural Tube Defects ,Spinal Dysraphism ,United States - Abstract
Tethered cord syndrome (TCS) is an occult spinal dysraphism that includes low lying conus, tight filum terminale, lipomeningomyelocele, split cord malformations, dermal sinus tracts, and dermoids. This congenital disorder has been associated with musculoskeletal, neurological, and gastrointestinal abnormalities. This study presents a retrospective review of the prospectively collected data of TCS patients and their concurrent diagnoses or associated anomalies.The National Inpatient Sample (NIS) database from 2003 to 2012 was used for data collection. Hospital- and year-adjusted weights allowed for accurate assessment of the incidence of TCS, as well as cardiac and gastrointestinal (GI) and genitourinary (GU) anomalies. K-means clustering analysis was run to discover patterns of concurrent cardiac, GI, GU, and other system anomalies in TCS patients.A total of 13,470 discharges with a diagnosis of TCS were identified in the NIS database, and at least one additional anomaly was identified in 40.7% of TCS patients. The most common secondary anomalies by system were: spine (24.48%), cardiac (6.27%), and urinary (5.37%). For patients with multiple anomalies, the most common combinations were GI and cardiac (4.55%), urinary and GI (4.26%), and urinary and cardiac (4.19%). The most common spinal association was spina bifida (13.65%). The most common neurological or musculoskeletal anomaly was any VACTERL association (13.45%). The top relation in GI and GU anomalies was cervix and female genitalia anomalies (69.1%). The most common specific anomalies were spina bifida, large intestine atresia, Rubenstein-Taybi syndrome, and atrial and ventral septal defects.This study provides a nationwide prospective on congenital anomalies and concurrent conditions present in tethered cord syndrome patients in the United States and demonstrates that 40.7% of TCS patients have at least one associated anomaly. The most common congenital anomalies studied were spina bifida, urogenital with or without cardiac septal defects, and cystourethral anomaly or cystic kidney disease with or without large intestinal atresia.
- Published
- 2020
30. Modelling of temperature and strain rate dependent behaviour of pearlitic steel in block braked railway wheels
- Author
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Esmaeili, Ali, Ahlstrom, Johan, Ekh, Magnus, Dimitrios, Nikas, Vernersson, Tore, Esmaeili, Ali, Ahlstrom, Johan, Ekh, Magnus, Dimitrios, Nikas, and Vernersson, Tore
- Abstract
Block braked railway wheels are subjected to thermal and rolling contact loading. The thermal loading results in high temperatures and thermal stresses which cause slow time dependent processes such as creep, relaxation and static recovery of the wheel material. At the same time, the rolling contact loading implies a very fast mechanical load application. This paper is focused on material modeling of pearlitic steel for a wide range of loading rates at elevated temperatures. The starting point is a viscoplasticity model including nonlinear isotropic and kinematic hardening. The Delobelle overstress function is employed to capture strain rate dependent response of the material. The model also includes static recovery of the hardening to capture slower viscous (diffusion dominated) behaviour of the material. Experiments for the pearlitic wheel steel ER7 in terms of cyclic strain-controlled uniaxial tests with hold-time, uniaxial ratchetting tests including rapid cycles and biaxial cyclic tests with tension/compression and torsion are used to calibrate the material model. These experiments were performed under isothermal conditions at different temperatures. In the ratchetting tests, higher loading rates are obtained and these have been used to calibrate the high strain rate response of the viscoplasticity model. The paper is concluded with a numerical example of a block braked wheel where the importance of accounting for the viscoplasticity in modelling is highlighted.
- Published
- 2021
- Full Text
- View/download PDF
31. Patients with Atrial Fibrillation and Chronic Kidney Disease More Often Undergo Angioplasty of Left Main Coronary Artery – a 867 Patient Study
- Author
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Jolanta Malyszko, Elzbieta Mlodawska, Hanna Bachórzewska-Gajewska, Anna Tomaszuk-Kazberuk, Dimitrios Nikas, Sławomir Dobrzycki, Ioannis Goudevenos, Paulina Lopatowska, and Bożena Sobkowicz
- Subjects
Male ,lcsh:Diseases of the circulatory (Cardiovascular) system ,medicine.medical_treatment ,030232 urology & nephrology ,030204 cardiovascular system & hematology ,Coronary Angiography ,urologic and male genital diseases ,lcsh:RC870-923 ,Coronary artery disease ,0302 clinical medicine ,lcsh:Dermatology ,Hospital Mortality ,Myocardial infarction ,Estimated glomerular filtration rate ,Aged, 80 and over ,education.field_of_study ,Atrial fibrillation ,General Medicine ,Middle Aged ,Coronary Vessels ,medicine.anatomical_structure ,Nephrology ,Cardiology ,Female ,Cardiology and Cardiovascular Medicine ,Glomerular Filtration Rate ,medicine.medical_specialty ,Population ,03 medical and health sciences ,Percutaneous Coronary Intervention ,Kidney function ,Internal medicine ,Angioplasty ,medicine ,Humans ,Renal Insufficiency, Chronic ,education ,Retrospective Studies ,business.industry ,Anticoagulants ,Percutaneous coronary intervention ,lcsh:RL1-803 ,medicine.disease ,lcsh:Diseases of the genitourinary system. Urology ,Coronary arteries ,lcsh:RC666-701 ,business ,Kidney disease - Abstract
Background/Aims: Several studies have implicated atrial fibrillation (AF) as a contributing factor in chronic kidney disease (CKD) and cardiovascular events. The prevalence of coronary artery disease (CAD) in patients with AF varies substantially from 17% to 46.5%. There are only few studies concerning renal function in population with AF undergoing coronary angiography. The aim of the present study was to assess which type of AF is dominant in CKD population scheduled for coronary angiography and if it can influence patients’ outcome, the association between renal impairment and the type of coronary procedures in AF patients and the influence of renal function on in-hospital mortality. Methods: We retrospectively studied 867 patients with AF hospitalized due to coronary angiography in two year time. The cut off value of CKD was eGFR ≤ 60 ml/min./1.73m2 evaluated by CKD-EPI formula. Results: A total of 867 patients with AF (44% women; mean age 72±10 years) were included in the analysis. The mean eGFR was 44±11ml/min./1.73m2 in patients with CKD and 89±18 ml/min./1.73m2 in patients with preserved renal function. Patients with CKD and AF were older (p< 0.001), had more often diabetes (p=0.009), heart failure (p< 0.001) and anaemia (p< 0.001). Patients with CKD and AF had more often permanent type of AF (p< 0.001). In CKD patients CHA2DS2VASc score was 4.3±1.5 and HAS-BLED score was 2.0±1.2 and it was significantly higher as compared to population with preserved renal function (p< 0.001, p=0.02, respectively). The use of oral anticoagulation was less frequent in CKD group (p< 0.001) although these patients had higher CHA2DS2VASc score. Patients with AF and CKD were more often admitted due to myocardial infarction (STEMI or NSTEMI) (p=0.02, p< 0.001, respectively) and more often underwent percutaneous coronary intervention (PCI) (p=0.01). Among coronary arteries the percutaneous coronary intervention (PCI) of left main artery was done more frequently in CKD patients (p=0.01). Among CKD population in-hospital mortality was significantly higher in patients with eGFR < 30 ml/min (p< 0.001). Conclusion: Patients with CKD had more often permanent type of AF. Percutaneous interventions of the left main coronary artery, the only elective procedures influencing patients’ prognosis, were done more frequently in CKD patients with AF. In-hospital mortality was significantly higher in patients with severe renal impairment. Despite the higher risk of ischaemic stroke in CKD group the use of oral anticoagulation therapy was significantly less frequent and the patients were deprived of the confirmed benefits of such treatment.
- Published
- 2018
32. Evaluation of local strength via microstructural quantification in a pearlitic rail steel deformed by simultaneous compression and torsion
- Author
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Xiaodan Zhang, Dimitrios Nikas, and Johan Ahlström
- Subjects
Materials science ,02 engineering and technology ,01 natural sciences ,Indentation hardness ,chemistry.chemical_compound ,Hardness ,0103 physical sciences ,Shear stress ,Dislocation density ,General Materials Science ,Surface layer ,Composite material ,Strengthening mechanisms of materials ,010302 applied physics ,Strengthening mechanisms ,Cementite ,Mechanical Engineering ,Torsion (mechanics) ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,chemistry ,Shear (geology) ,Mechanics of Materials ,TEM ,0210 nano-technology ,Material properties ,Pearlitic rail steel - Abstract
Pearlitic steels are commonly used for railway rails because they combine good strength and wear properties. During service, the passage of trains results in large accumulation of shear strains in the surface layer of the rail, sometimes leading to crack initiation. Knowledge of the material properties versus the shear strain in this layer is therefore important for fatigue life predictions. In this study, fully pearlitic R260 rail steel was deformed using a bi-axial torsion-compression machine to reach different shear strains. Microstructural parameters including interlamellar spacing, thickness of ferrite and cementite lamellae and dislocation density in the ferrite lamellae, as well as hardness were quantitatively characterized at different shear strain levels. Based on the microstructural observations and the quantification of the microstructural parameters, the local flow stresses were estimated based on boundary strengthening and dislocation strengthening models. A good agreement was found between the estimated flow stresses and the flow stresses determined from microhardness measurements.
- Published
- 2018
- Full Text
- View/download PDF
33. RECURRENT RIGHT COLON CANCER: CHALLENGES AND RESULTS
- Author
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Theodoros Piperos, Alexandra Varlatzidou, Christos Sioros, Dimitrios Nikas, Aikaterini Foutsitzi, Maria Zarokosta, Eirini Nomikou, Savvas Tanteles, and Theodoros Mariolis-Sapsakos
- Subjects
Oncology ,Surgery ,General Medicine - Published
- 2022
- Full Text
- View/download PDF
34. Acute myocardial infarction in a young bodybuilder taking anabolic androgenic steroids: A case report and critical review of the literature
- Author
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John A. Goudevenos, Konstantinos A Christou, Dimitrios Nikas, and Georgios A Christou
- Subjects
Adult ,Male ,medicine.medical_specialty ,Epidemiology ,health care facilities, manpower, and services ,Context (language use) ,030204 cardiovascular system & hematology ,Electrocardiography ,03 medical and health sciences ,Anabolic Agents ,0302 clinical medicine ,Internal medicine ,medicine ,Humans ,cardiovascular diseases ,030212 general & internal medicine ,Myocardial infarction ,Thrombus ,health care economics and organizations ,Stanozolol ,Coronary atherosclerosis ,Doping in Sports ,Somatotypes ,business.industry ,Vasospasm ,medicine.disease ,Thrombosis ,Surgery ,Athletes ,Echocardiography ,Cardiology ,ST Elevation Myocardial Infarction ,Cardiology and Cardiovascular Medicine ,business ,medicine.drug ,Medical literature - Abstract
We describe a case report of a 30-year-old bodybuilder suffering acute myocardial infarction (AMI). He had been taking stanozolol and testosterone for two months. The coronary angiogram showed high thrombotic burden in the left anterior descending artery without underlying atherosclerosis. Few case reports of AMI in athletes taking anabolic androgenic steroids (AASs) have been reported so far. AAS-related AMI is possibly underreported in the medical literature due to the desire of the affected individuals to hide AAS use. Physicians should always consider the possibility of AAS abuse in the context of a young athlete suffering AMI. AASs can predispose to AMI through the acceleration of coronary atherosclerosis. Additionally, thrombosis without underlying atherosclerosis or vasospasm is highly possible to cause AMI in AAS users. Complications after AMI may be more frequent in AAS users.
- Published
- 2016
- Full Text
- View/download PDF
35. Impact on outcome of different types of carotid stent: results from the European Registry of Carotid Artery Stenting
- Author
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Gianmarco de Donato, Andrej Schmidt, Piergiorgio Cao, Paolo Rubino, Horst Sievert, Marc Bosiers, Anna Sannino, Patrick Peeters, Giovanni Esposito, Bernhard Reimers, Eugenio Stabile, Marius Hornung, Giambattista Parlani, Carlo Setacci, Giuseppe Giugliano, Alberto Cremonesi, Fausto Castriota, Tullio Tesorio, Dimitrios Nikas, Stabile, Eugenio, Giugliano, Giuseppe, Cremonesi, Alberto, Bosiers, Marc, Reimers, Bernhard, Setacci, Carlo, Cao, Piergiorgio, Schmidt, Andrej, Sievert, Horst, Peeters, Patrick, Nikas, Dimitrio, Sannino, Anna, De Donato, Gianmarco, Parlani, Giambattista, Castriota, Fausto, Hornung, Mariu, Rubino, Paolo, Esposito, Giovanni, and Tesorio, Tullio
- Subjects
Carotid Artery Diseases ,Male ,medicine.medical_specialty ,Time Factors ,medicine.medical_treatment ,Carotid arteries ,Population ,030204 cardiovascular system & hematology ,Prosthesis Design ,Risk Assessment ,Stroke risk ,03 medical and health sciences ,0302 clinical medicine ,Risk Factors ,Angioplasty ,80 and over ,Stent ,medicine ,Humans ,Carotid Stenosis ,Registries ,cardiovascular diseases ,education ,Stroke ,Aged ,Aged, 80 and over ,education.field_of_study ,business.industry ,Mortality rate ,Carotid arterie ,Middle Aged ,medicine.disease ,Stents ,Female ,Treatment Outcome ,Cardiology and Cardiovascular Medicine ,Surgery ,business ,030217 neurology & neurosurgery ,Carotid stent - Abstract
AIMS: Conflicting data exist on the impact on outcome of the use of different stent types during carotid artery stenting (CAS). The aim of this study was to evaluate clinical outcomes according to different carotid stent design among the population of the European Registry of Carotid Artery Stenting (ERCAS). METHODS AND RESULTS: The present study was conducted in 1,604 patients who underwent neuroprotected CAS in ERCAS. All types of commercially available carotid stent were used. Open-cell design stents were classified according to free cell area into 7.5 mm2. A total of 713 closed-cell, 456 hybrid-cell, 238 7.5 mm2 open-cell stents were implanted. Overall, the 30-day stroke and death rate was 1.37%. At 30 days, 19 strokes occurred (1.18%): eight in the group of patients treated with a closed-cell (1.12%), two in those with a hybrid-cell (0.44%), three in those with a 7.5 mm2 open-cell stent (3.05%) (p=0.045). CONCLUSIONS: Data of the present study suggest that, in the setting of neuroprotected CAS performed in high-volume centres by properly trained operators, the use of an open-cell design stent with a free cell area >7.5 mm2 may be associated with an increased 30-day stroke risk.
- Published
- 2016
- Full Text
- View/download PDF
36. High temperature bi-axial low cycle fatigue behaviour of railway wheel steel
- Author
-
Johan Ahlström and Dimitrios Nikas
- Subjects
Materials science ,lcsh:TA1-2040 ,Ferrite (iron) ,Thermal ,Hardening (metallurgy) ,Low-cycle fatigue ,Thin walled ,Slippage ,Strain hardening exponent ,Composite material ,Microstructure ,lcsh:Engineering (General). Civil engineering (General) - Abstract
One of the most important aspects in railway operation is the interaction between rail and wheel. Railway wheels are commonly made from medium carbon steels (similar to 0.55 wt.% C), heat treated to a near pearlitic microstructure with some 5-10% pro-eutectoid ferrite. During the operation of freight trains, where block brakes are used, high thermal loads are evolved because of recurring braking and occasional slippage. Thus the combination of mechanical and thermal loads leads to changes in the mechanical properties of the material. The focus of the current investigation is to evaluate the mechanical behaviour of wheel material (UIC ER7T) subjected to non-proportional biaxial fatigue loading, as this simulates the actual working conditions in a better way than uniaxial loading. Axial-torsional low cycle fatigue tests were performed at room temperature and elevated temperatures using thin walled specimens to study the cyclic stress-strain properties of this material. The results showed large influence of temperature on the ratcheting behaviour of the material. Biaxial non-proportional loading gave much higher strain hardening as compared to uniaxial loading. Hardening due to dynamic strain ageing can be seen in the biaxial tests at temperatures around 300 degrees C.
- Published
- 2019
37. De Novo Formation of Direct Arteriovenous Fistula Involving Anterior Communicating Artery Aneurysm in Remote Site from Prior Ruptured Arteriovenous Malformation in Pediatric Patient: Case Report and Review of Literature
- Author
-
Torin Karsonovich, Dimitrios Nikas, Ryan Johnson, and Hamad Farhat
- Subjects
Intracranial Arteriovenous Malformations ,medicine.medical_specialty ,Adolescent ,Arteriovenous fistula ,Ventriculoperitoneal Shunt ,03 medical and health sciences ,0302 clinical medicine ,Aneurysm ,medicine.artery ,medicine ,Humans ,cardiovascular diseases ,Intraparenchymal hemorrhage ,business.industry ,Inferior petrosal sinus ,Angiography, Digital Subtraction ,Arteriovenous malformation ,Intracranial Aneurysm ,medicine.disease ,Cerebral Angiography ,Anterior communicating artery ,Intraventricular hemorrhage ,Treatment Outcome ,030220 oncology & carcinogenesis ,Arteriovenous Fistula ,Etiology ,Surgery ,Female ,Neurology (clinical) ,Radiology ,business ,030217 neurology & neurosurgery - Abstract
Background De novo formation of arteriovenous malformations (AVMs) and arteriovenous fistulas (AVFs) is increasingly being reported in the neurosurgical literature, challenging the notion that AVMs are congenital in origin. Most of this literature centers around the pediatric population. After treatment of an AVM or AVF, recurrence, if any, appears to occur locally to the original insult. We present, to the best of our knowledge, the first case of a de novo direct AVF involving an anterior communicating artery aneurysm in a remote site from a prior ruptured AVM in a pediatric patient. Case Description We present a case of a 14-year-old female who presented 2 years prior with an intraparenchymal hemorrhage secondary to a left parietal arteriovenous malformation. That AVM was successfully microsurgically resected and revealed complete angiographic obliteration on postoperative and surveillance angiograms. This patient now presents with a spontaneous intraventricular hemorrhage secondary to a ruptured anterior communicating artery complex aneurysm with a fistulous connection from this aneurysm to the inferior petrosal sinus. The aneurysm and direct AVF were not identified on prior surveillance imaging, indicating de novo formation in a remote site from her prior AVM. Conclusions This case highlights the importance of long-term imaging surveillance in patients with AVMs. Further prospective studies are indicated to evaluate the long-term imaging surveillance necessary to detect early recurrence, thereby allowing doctors to institute earlier definitive treatment. The exact pathophysiology behind these lesions is not fully understood; however, this case lends support to an acquired etiology to vascular malformations.
- Published
- 2018
38. The Current Role of Omega-3 Fatty Acids in the Management of Atrial Fibrillation
- Author
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Georgios A Christou, John A. Goudevenos, Konstantinos A Christou, Evangelos C. Rizos, Dimitrios Nikas, and Panagiotis Korantzopoulos
- Subjects
eicosapentaenoic acid ,medicine.medical_specialty ,medicine.medical_treatment ,Management of atrial fibrillation ,Review ,arrhythmia ,Cardioversion ,fish oil ,Catalysis ,lcsh:Chemistry ,Inorganic Chemistry ,cardioversion ,Internal medicine ,Fatty Acids, Omega-3 ,medicine ,Animals ,Humans ,atrial fibrillation ,Cardiac Surgical Procedures ,Physical and Theoretical Chemistry ,lcsh:QH301-705.5 ,Molecular Biology ,Spectroscopy ,chemistry.chemical_classification ,omega-3 fatty acids ,business.industry ,Organic Chemistry ,Atrial fibrillation ,General Medicine ,docosahexaenoic acid ,medicine.disease ,Fish oil ,Eicosapentaenoic acid ,Computer Science Applications ,Cardiac surgery ,lcsh:Biology (General) ,lcsh:QD1-999 ,chemistry ,Docosahexaenoic acid ,Dietary Supplements ,Cardiology ,lipids (amino acids, peptides, and proteins) ,business ,Anti-Arrhythmia Agents ,cardiac surgery ,Polyunsaturated fatty acid - Abstract
Background: The main dietary source of omega-3 polyunsaturated fatty acids (n-3 PUFA) is fish, which contains eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In the present manuscript, we aimed to review the current evidence regarding the clinical role of n-3 PUFA in the prevention of atrial fibrillation (AF) and the possible underlying mechanisms. Methods: A literature search based on PubMed listings was performed using “Omega-3 fatty acids” and “atrial fibrilation” as key search terms. Results: n-3 PUFA have been shown to attenuate structural atrial remodeling, prolong atrial effective refractory period through the prevention of reentry and suppress ectopic firing from pulmonary veins. Dietary fish intake has been found to have no effect on the incidence of AF in the majority of studies. Circulating DHA has been consistently reported to be inversely associated with AF risk, whereas EPA has no such effect. The majority of studies investigating the impact of n-3 PUFA supplementation on the incidence of AF following cardiac surgery reported no benefit, though most of them did not use n-3 PUFA pretreatment for adequate duration. Studies using adequate four-week pretreatment with n-3 PUFA before cardioversion of AF showed a reduction of the AF incidence. Conclusions: Although n-3 PUFA have antiarrhythmogenic properties, their clinical efficacy on the prevention of AF is not consistently supported. Further well-designed studies are needed to overcome the limitations of the existing studies and provide robust conclusions.
- Published
- 2015
- Full Text
- View/download PDF
39. High temperature bi-axial low cycle fatigue behaviour of railway wheel steel
- Author
-
Dimitrios, Nikas, Ahlström, Johan, Dimitrios, Nikas, and Ahlström, Johan
- Abstract
One of the most important aspects in railway operation is the interaction between rail and wheel. Railway wheels are commonly made from medium carbon steels (similar to 0.55 wt.% C), heat treated to a near pearlitic microstructure with some 5-10% pro-eutectoid ferrite. During the operation of freight trains, where block brakes are used, high thermal loads are evolved because of recurring braking and occasional slippage. Thus the combination of mechanical and thermal loads leads to changes in the mechanical properties of the material. The focus of the current investigation is to evaluate the mechanical behaviour of wheel material (UIC ER7T) subjected to non-proportional biaxial fatigue loading, as this simulates the actual working conditions in a better way than uniaxial loading. Axial-torsional low cycle fatigue tests were performed at room temperature and elevated temperatures using thin walled specimens to study the cyclic stress-strain properties of this material. The results showed large influence of temperature on the ratcheting behaviour of the material. Biaxial non-proportional loading gave much higher strain hardening as compared to uniaxial loading. Hardening due to dynamic strain ageing can be seen in the biaxial tests at temperatures around 300 degrees C.
- Published
- 2019
- Full Text
- View/download PDF
40. Primary Ewing sarcoma of the axis-C2: A case report and the review of the literature
- Author
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Paraskeva, Kyriakos Giakoumettis, Dimitrios Nikas, Ioannis and Georgoulis, George Sfakianos, George Themistocleous, Marios S.
- Abstract
Introduction: Neck pain and torticollis are common symptoms in the pediatric population that rarely requires further investigation. However, in case symptoms persist, then a more meticulously approach should be considered. Underlying conditions such as infections, neck injury, autoimmune disorders or even cervical spine cancer should be excluded from diagnosis. Cervical spine cancer is a rare neurosurgical entity in the pediatric population and even rarer is atlantoaxial Ewing's sarcoma. In this report, we present a rare case of primary Ewing's sarcoma of the axis. Case report: A 3.5-year-old female with progressive neck pain and intermittent episodes of torticollis was referred to our outpatient clinic. Imaging studies revealed a malignant tumor located on C2 vertebra. Diagnosis of Ewing's Sarcomawas confirmed via open biopsy and the patient was treated with Euro-EWING 99 chemotherapy. Conclusion: Pediatric neck pain and/or torticollis should raise high suspicion for malignancy of cervical spine. Modern diagnostic means and techniques can assist in the screening and diagnosis of these tumors. (C) 2018 Polish Neurological Society. Published by Elsevier Sp. z o. o. All rights reserved.
- Published
- 2018
41. Microstructure and mechanical properties of the running band in a pearlitic rail steel: Comparison between biaxially deformed steel and field samples
- Author
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Johan Ahlström, Knut Andreas Meyer, and Dimitrios Nikas
- Subjects
Materials science ,Cementite ,Metallurgy ,02 engineering and technology ,Surfaces and Interfaces ,Materials testing ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,020303 mechanical engineering & transports ,0203 mechanical engineering ,chemistry ,Shear (geology) ,Mechanics of Materials ,Materials Chemistry ,Axial torsion ,Surface layer ,Composite material ,0210 nano-technology - Abstract
The large deformations occurring in the surface layer of rail heads strongly influence the material behavior. Cracks typically develop from this critical region. However, conventional material testing of this layer is not possible due to the large gradients. A method for obtaining a similar material through predeformation is therefore investigated. Subsequent analyses of the obtained material can improve our understanding of the material behavior close to the running band. Hardness, shear lines and cementite lamella orientation distributions are compared in order to determine whether the obtained material is similar to that of the field samples extracted from rails that have been in service for several years. The predeformation method produces a consistent material, which is representative of the material in the rail field samples that have accumulated large shear strains.
- Published
- 2018
- Full Text
- View/download PDF
42. Fast virtual functional assessment of intermediate coronary lesions using routine angiographic data and blood flow simulation in humans: comparison with pressure wire – fractional flow reserve
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Katerina K. Naka, Yuki Ishibashi, Lampros K. Michalis, Takashi Muramatsu, Owen Mogabgab, Jurgen Ligthart, Shimpei Nakatani, Javier Escaned, Felix Zijlstra, Michail I. Papafaklis, Lampros Lakkas, Mauro Echavarria-Pinto, Anna Kotsia, Yoshinobu Onuma, Emmanouil S. Brilakis, Patrick W. Serruys, Hector M. Garcia-Garcia, Dimitrios I. Fotiadis, Dimitrios Nikas, Robert-Jan van Geuns, Christos V. Bourantas, Georgia Tsirka, and Cardiology
- Subjects
Male ,medicine.medical_specialty ,Hemodynamics ,Fractional flow reserve ,Coronary Angiography ,Hyperaemia ,Imaging, Three-Dimensional ,medicine ,Humans ,Computer Simulation ,Aged ,Retrospective Studies ,medicine.diagnostic_test ,Receiver operating characteristic ,business.industry ,Coronary Stenosis ,Models, Cardiovascular ,Blood flow ,Middle Aged ,medicine.disease ,Pressure wire ,Fractional Flow Reserve, Myocardial ,Stenosis ,Angiography ,Female ,Radiology ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,Nuclear medicine ,business - Abstract
Aims: To develop a simplified approach of virtual functional assessment of coronary stenosis from routine angiographic data and test it against fractional flow reserve using a pressure wire (wire-FFR). Methods and results: Three-dimensional quantitative coronary angiography (3D-QCA) was performed in 139 vessels (120 patients) with intermediate lesions assessed by wire-FFR (reference standard
- Published
- 2014
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- View/download PDF
43. Evaluation of the thickness and roughness of homogeneous surface layers on spherical and irregular powder particles
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Eduard Hryha, Dimitrios Nikas, Lars Nyborg, and Christos Oikonomou
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Materials science ,Analytical chemistry ,Oxide ,Surfaces and Interfaces ,General Chemistry ,Surface finish ,Photoelectric effect ,Condensed Matter Physics ,Focused ion beam ,Surfaces, Coatings and Films ,Ion ,chemistry.chemical_compound ,X-ray photoelectron spectroscopy ,chemistry ,Materials Chemistry ,Surface roughness ,Metal powder ,Composite material - Abstract
The present study describes the development of a theoretical model for estimating the thickness of homogeneous surface layers on spherical and irregular shaped powder particles using the XPS depth profiling. As opposed to flat surfaces, such an approach for substrates of specific geometry is not straightforward. One needs to consider those geometrical factors associated with the experimental setup and sample’s roughness, which impose an angle dependence on the photoelectrons peak intensity, X-ray flux and ion etch rate over the surface in question in order to evaluate it. The novelty of the current model lies in the introduction of geometrical freedom in connection to the experimental arrangement, which can be tailored to match the needs of contemporary instruments. The model was evaluated experimentally by analyzing the surface oxide layers on metal powder grades of different morphology. Complementary analytical techniques such as high resolution (HR) SEM and focused ion beam (FIB) were used in combination to further characterize the surface layers prior to the XPS investigations. The results reveal that the estimation of the oxide/metal interface from the measured relative metal intensity signal as function of etch depth using the model is in extremely good agreement with the corresponding values from direct measurement of HR SEM on FIB cross-sectioned powder samples. The model deviates slightly only for the irregular shaped powder, which can be regarded as means for quantification of surface roughness of the material. The model is used as a basis for a computer software that estimates the thickness of surface layers for powdered materials.
- Published
- 2014
- Full Text
- View/download PDF
44. Microstructure and mechanical properties of the running band in a pearlitic rail steel : Comparison between biaxially deformed steel and field samples
- Author
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Meyer, Knut Andreas, Dimitrios, Nikas, Ahlström, Johan, Meyer, Knut Andreas, Dimitrios, Nikas, and Ahlström, Johan
- Abstract
The large deformations occurring in the surface layer of rail heads strongly influence the material behavior. Cracks typically develop from this critical region. However, conventional material testing of this layer is not possible due to the large gradients. A method for obtaining a similar material through predeformation is therefore investigated. Subsequent analyses of the obtained material can improve our understanding of the material behavior close to the running band. Hardness, shear lines and cementite lamella orientation distributions are compared in order to determine whether the obtained material is similar to that of the field samples extracted from rails that have been in service for several years. The predeformation method produces a consistent material, which is representative of the material in the rail field samples that have accumulated large shear strains.
- Published
- 2018
- Full Text
- View/download PDF
45. Evaluation of local strength via microstructural quantification in a pearlitic rail steel deformed by simultaneous compression and torsion
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Dimitrios, Nikas, Zhang, Xiaodan, Ahlström, Johan, Dimitrios, Nikas, Zhang, Xiaodan, and Ahlström, Johan
- Abstract
Pearlitic steels are commonly used for railway rails because they combine good strength and wear properties. During service, the passage of trains results in large accumulation of shear strains in the surface layer of the rail, sometimes leading to crack initiation. Knowledge of the material properties versus the shear strain in this layer is therefore important for fatigue life predictions. In this study, fully pearlitic R260 rail steel was deformed using a bi-axial torsion-compression machine to reach different shear strains. Microstructural parameters including interlamellar spacing, thickness of ferrite and cementite lamellae and dislocation density in the ferrite lamellae, as well as hardness were quantitatively characterized at different shear strain levels. Based on the microstructural observations and the quantification of the microstructural parameters, the local flow stresses were estimated based on boundary strengthening and dislocation strengthening models. A good agreement was found between the estimated flow stresses and the flow stresses determined from microhardness measurements. d
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- 2018
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46. Influence of combined thermal and mechanical loadings on pearlitic steel microstructure in railway wheels and rails
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Dimitrios, Nikas and Dimitrios, Nikas
- Abstract
One of the most important aspects in railway operation is the interaction between rail and wheel. The contact patch between these two components is around the size of a small coin, and since high loads act on this small area, stresses will give rise to wear and damage in both components. Frictional forces on the surface of wheels and rails caused by recurring train acceleration, braking, curving and occasional slippage can cause cyclic plastic deformation and heating, which in turn causes an aligned, anisotropic microstructure with altered mechanical behaviour. Control of material property degradation is an important topic for guiding maintenance, as well as ensuring safety of railways, since it will allow for a more accurate prediction of material wear and lifetime. The thesis focuses on the mechanical properties of railway wheel and rail steels after exposure to elevated temperatures and plastic deformation. Specifically examined are the carbon wheel steels, UIC ER7T and ER8T (~0.55 wt. %C) and rail steel R260 (~0.72 wt. %C). During their service life, the surface layers of rails and wheels are subjected to very high rolling contact loads. These lead to accumulation of large shear strains close to the running surface. Moreover the high thermal loads that wheels experience when block brakes are used can cause severe degradation of the material microstructure, more specifically spheroidisation of the pearlite, which combined with plastic deformation (that makes the material more prone to spheroidisation) can lead to severe deterioration of the material’s mechanical properties. Both un-deformed and pre-strained wheel materials were heat treated at various temperatures from 250°C to 600°C for various durations, and the change in room temperature hardness was analysed. Additionally, Electron Backscatter Diffraction Analysis (EBSD) was used to evaluate if orientation gradients in the pearlitic colonies affect the spheroidisation of the pearlitic microstructure, that is
- Published
- 2018
47. Recent developments of imaging modalities of carotid artery stenting
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Tomoyuki Umemoto, Dimitrios Nikas, Andrea Pacchioni, and Bernhard Reimers
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Carotid Artery Diseases ,Male ,medicine.medical_specialty ,genetic structures ,Carotid arteries ,medicine.medical_treatment ,Severity of Illness Index ,030218 nuclear medicine & medical imaging ,Imaging modalities ,03 medical and health sciences ,0302 clinical medicine ,Predictive Value of Tests ,Risk Factors ,Intravascular ultrasound ,medicine ,Humans ,cardiovascular diseases ,Ultrasonography, Interventional ,Aged ,Spectroscopy, Near-Infrared ,Modalities ,Modality (human–computer interaction) ,medicine.diagnostic_test ,business.industry ,Angioplasty ,Angiography, Digital Subtraction ,Reproducibility of Results ,Stent ,General Medicine ,Middle Aged ,equipment and supplies ,Cerebral Angiography ,Diffusion Magnetic Resonance Imaging ,Treatment Outcome ,surgical procedures, operative ,030220 oncology & carcinogenesis ,Angiography ,cardiovascular system ,Female ,Stents ,Surgery ,Radiology ,Tomography ,Diffusion of Innovation ,Cardiology and Cardiovascular Medicine ,business ,Tomography, Optical Coherence - Abstract
Compared with conventional angiogram-guided procedure, intravascular imaging modalities give us a lot of useful information to make the procedure better. Intravascular imaging modalities give us the information about lesion characters, reference vessel diameter and the interaction between the stent strut and the plaque such as stent strut malapposition or plaque prolapse in real time during the procedure. We can change our strategy according to this information. Intravascular ultrasound (IVUS) is a most common intravascular imaging modality during carotid artery stenting (CAS) in these days. Its advantage is easy to use compared with optical coherence tomograpy (OCT) which has been reported recently in some case reports or case series. However, due to its high resolution, OCT provides more detailed information especially about plaque prolapse and strut malapposition. IVUS and OCT have a potential to improve acute result and reduce the procedural complication by providing the data of lesion character, reference vessel diameter and the interaction of stent strut and vessel wall. Interventionalists who perform CAS procedure should acquire proficiency in imaging modalities during CAS procedure.
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- 2017
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48. Update on new stents and protection devices for carotid artery stenting: what we know, what we learnt recently and what we need to know
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George Liappas, Tomoyuki Umemoto, Bernhard Reimers, Narek Zakarian, Dimitrios Nikas, Xenofon Makos, and Andrea Pacchioni
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Carotid Artery Diseases ,Male ,medicine.medical_specialty ,medicine.medical_treatment ,Carotid arteries ,Carotid endarterectomy ,030204 cardiovascular system & hematology ,Stroke mortality ,Prosthesis Design ,Embolic Protection Devices ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Need to know ,Risk Factors ,medicine ,Prosthesis design ,Humans ,Intensive care medicine ,Aged ,Aged, 80 and over ,business.industry ,Angioplasty ,General Medicine ,Middle Aged ,medicine.disease ,Surgery ,Stroke ,Stenosis ,Treatment Outcome ,Female ,Stents ,Cardiology and Cardiovascular Medicine ,business ,Stent design - Abstract
Carotid artery stenting (CAS) is considered an alternative option to carotid endarterectomy (CEA) for significant carotid stenosis, in both symptomatic and asymptomatic patients. Comparing to CEA, CAS offers significant advantages. The most important arise from the minimally invasive nature of the procedure, which reduces the surgical complications and adds significant comfort to the patient, without compromising the efficacy. Nowadays, CAS can achieve acute and long-term outcome results comparable to CEA, maintaining low rates of periprocedural embolic events. Evolution of the stent design and routine application of protection devices, played an important role to CAS performance. In this review, we aim to present all available new data on stent design and protection devices while we pose a set of unanswered questions that need to be addressed in the future.
- Published
- 2016
49. Congress of Neurological Surgeons Systematic Review and Evidence-Based Guideline on the Management of Patients With Positional Plagiocephaly: The Role of Repositioning
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Paul Klimo, Patrick Ryan Lingo, Lissa C. Baird, David F. Bauer, Alexandra Beier, Susan Durham, Alexander Y. Lin, Catherine McClung-Smith, Laura Mitchell, Dimitrios Nikas, Mandeep S. Tamber, Rachana Tyagi, Catherine Mazzola, and Ann Marie Flannery
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Evidence-Based Medicine ,Plagiocephaly, Nonsynostotic ,Plagiocephaly ,Neurosurgery ,Infant ,Positional plagiocephaly ,Practice guidelines ,Patient Positioning ,03 medical and health sciences ,0302 clinical medicine ,030225 pediatrics ,Humans ,Surgery ,Neurology (clinical) ,Sleep ,Infants ,030217 neurology & neurosurgery - Abstract
BACKGROUND: Plagiocephaly, involving positional deformity of the calvarium in infants, is one of the most common reasons for pediatric neurosurgical consultation. OBJECTIVE: To answer the question: “what is the evidence for the effectiveness of repositioning for positional plagiocephaly?” Treatment recommendations are provided based on the available evidence. METHODS: The National Library of Medicine MEDLINE database and the Cochrane Library were queried using MeSH headings and key words relevant to repositioning as a means to treat plagiocephaly and brachycephaly. Abstracts were reviewed to identify which studies met the inclusion criteria. An evidentiary table was assembled summarizing the studies and the quality of evidence (Classes I-III). Based on the quality of the literature, a recommendation was rendered (Level I, II, or III). RESULTS: There were 3 randomized trials (Class I), 1 prospective cohort study (Class II), and 6 retrospective cohort studies (Class III). Repositioning education was found to be equal to a repositioning device and inferior to a physical therapy program. Five of the 7 cohort studies comparing repositioning with a helmet reported helmets to be better and take less time. CONCLUSION: Within the limits of this systematic review, repositioning education is effective in affording some degree of correction in virtually all infants with positional plagiocephaly or brachycephaly. Most studies suggest that a molding helmet corrects asymmetry more rapidly and to a greater degree than repositioning education. In a Class I study, repositioning education was as effective as repositioning education in conjunction with a repositioning wrap/device. Another Class I study demonstrated that a bedding pillow was superior to physical therapy for some infants. However, in keeping with the American Academy of Pediatrics' warning against the use of soft positioning pillows in the sleeping environment, the Task Force recommends physical therapy over any positioning device. The full guidelines document can be located at https://www.cns.org/guidelines/guidelines-management-patients-positional-plagiocephaly/Chapter_3.
- Published
- 2016
50. Implantable cardioverter defibrillator lead placement in the right ventricular outflow tract in a patient with Brugada syndrome and persistent left superior vena cava
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Marios Kolios, Dimitrios Nikas, John A. Goudevenos, and Panagiotis Korantzopoulos
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medicine.medical_specialty ,business.industry ,medicine.medical_treatment ,medicine.disease ,Implantable cardioverter-defibrillator ,Internal medicine ,Cardiology ,Medicine ,Ventricular outflow tract ,Persistent left superior vena cava ,Cardiology and Cardiovascular Medicine ,business ,Lead Placement ,Brugada syndrome - Published
- 2015
- Full Text
- View/download PDF
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