Browsing by Author "Sahin S."
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Item Investigation of the effect on boride layer of powder particle size used in boronizing with solid boron-yielding substances(Elsevier Science Ltd, 2000) Meriç C.; Sahin S.; Yilmaz S.S.In this study, the effect of particle size of powder used in the boronizing process with solid boron-yielding substances on the boride layer was investigated. Hot-shaped AISI 1020, AISI 1030, AISI 1040, and AISI 1050 structural steels were used as the base materials. EKabor HM powder was used as the boronizing agent, and was classified into four groups according to particle size. The boronizing process was carried out with each group at 900 °C for 2, 3, 4, and 5 h. The microstructure, microhardness, and layer thickness of the boronized materials were investigated.Item Mechanical and metallurgical properties of brazed SAE 1040 and tungsten carbide(2002) Meric C.; Uzkut M.; Sahin S.[No abstract available]Item Investigation of effect of boronising on welding zone(2002) Meric C.; Sahin S.; Uzkut M.In the present study, AISI 1040 and AISI 8620 steels are joined by arc welding and gas metal arc welding, and then subjected to a solid boronising process at 850, 900, 950, and 1000°C using EKabor HM (tradename) for 4 h. The microhardness and thickness of the boride layers produced on the surfaces of the air cooled specimens are measured and the microstructures are photographed using optical microscopy. The effect of boronising in and around the welding zone is investigated.Item Investigation of the effect of boronizing on cast irons(2002) Sahin S.; Meric C.Gray iron, ductile iron and compacted graphite iron were boronized with solid boron-yielding substances by box-boronizing method. Commercial EKabor® 3 powder is used as the boronizing agent and the treatments are carried out at 850, 900 and 950°C for 2, 3, 4, 5 and 6 h. Thickness and microhardness of the boride layer, and the microstructure of the boronized specimens are reported. © 2002 Elsevier Science Ltd. All rights reserved.Item Residual thermal stress analysis in cylindrical steel bars using finite element method and artificial neural networks(2002) Toparli M.; Sahin S.; Ozkaya E.; Sasaki S.In this study, it was proposed that the residual stresses within steel bars after quenching in water from 600 °C could be calculated by using the finite element method (FEM) and an artificial neural network (ANN) algorithm. Three modelled cylindrical specimens of AISI 1020 steel were heated and then quenched in water. Using FEM, temperature distribution with time and thermal residual stress values in the samples were calculated after cooling. The analysis was extended to elastic-plastic deformation during the quenching of steel cylinders of various diameters. The calculated temperature and thermal residual stress values were used in training a multi-layer, feed forward, back propagation ANN algorithm. The results obtained via the ANN algorithm method have been compared with the FEM results. Comparison showed good agreement. © 2002 Elsevier Science Ltd. All rights reserved.Item The relationship between serum trace element changes and visual function in heavy smokers(2003) Uz E.; Sahin S.; Hepsen I.F.; Var A.; Sogut S.; Akyol Ö.Purpose: The aim of this prospective study was to evaluate serum manganese (Mn), zinc (Zn) and copper (Cu) levels and visual functions including visual acuity, colour vision, pattern visual evoked potentials (PVEPs), and contrast sensitivity in heavy smokers and to compare these with the equivalent levels and functions in non-smokers. Methods: Data were recorded in 24 healthy, chronic and heavy cigarette smokers and 16 healthy, non-smoking control subjects. Serum Zn, Cu and Mn concentrations in all subjects were measured by atomic absorption spectrophotometry. Results: Both study and control subjects had normal visual acuity and colour vision. Pattern visual evoked potentials were normal in all study and control subjects. Contrast sensitivity was significantly reduced in heavy smokers compared to non-smokers (p < 0.023), despite the fact that central vision and PVEP responses were not affected. Mean serum Mn and Zn levels were significantly lower in smokers than in non-smokers (p < 0.0001 and p < 0.005, respectively). Conclusions: Reduced contrast sensitivity values associated with low levels of serum Mn and Zn, which function as cofactors of superoxide dismutase in erythrocyte and other nucleated cells, suggest a possible role of trace elements in smoking-induced early retinal toxicity.Item Modelled and measured residual stresses in a bimaterial joint(2003) Sahin S.; Toparli M.; Ozdemir I.; Sasaki S.A finite element technique has been used to predict residual and thermal stresses due to welding. For this purpose, a steel-brass material couple was chosen and thin plates of the materials were hard brazed. The finite element study was carried out using two-dimensional models. After the temperature distributions as a result of welding were calculated, thermal and residual stress values obtained. Thermo-elasto-plastic formulations using a von-Mises yield criterion with linear isotropic-hardening were employed. For this deformation, the initial stress method was used and the kinematical Bauschinger effect was considered. The authors prepared all calculation programs using FORTRAN 77. To obtain residual stresses that occur during the welding, the hole-drilling strain-gage method was chosen and conducted in accordance with the ASTM Standard E 837-99. The agreement between the calculated results and the experimental data shows that the finite element analysis method is reliable. © 2002 Elsevier Science B.V. All rights reserved.Item Investigation of the boronizing effect on the abrasive wear behavior in cast irons(Elsevier Ltd, 2006) Meric C.; Sahin S.; Backir B.; Koksal N.S.One of the methods used to improve the surface properties of iron and steel is boronizing. Gray iron, ductile iron and compacted graphite iron were boronized with solid boron-yielding substances by pack-boronizing method. Commercial EKabor®3 powder was used as the boronizing agent and the treatment was carried out at 900 °C for 2, 3, 4, 5 and 6 h. Thickness, microhardness and microstructure of the boride layer are investigated. Abrasive wear behavior of the boronized and unboronized cast irons were investigated. For this purpose, the specimens were tested on a pin-on disk test apparatus. SAE 1040 steel was used as the moving surface member. Abrasive wear tests were carried out at a fixed load and a fixed sliding speed. The weight loss was measured and worn surfaces were examined. © 2005 Elsevier Ltd. All rights reserved.Item Item Characterization and determination of FexB layers' mechanical properties(2008) Culha O.; Toparli M.; Sahin S.; Aksoy T.The aim of this study is to obtain microstructural characteristics and investigate the mechanical properties such as hardness, Young's modulus and fracture toughness of the boride layer depending on process time and temperature. The produced double layers (FeB and Fe2B) were extensively analyzed with respect to X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD pattern of the boride layers, which were formed on SAE 1020 and 1040 quality steel at 900 °C for 2 h, 4 h and 6 h, include only FeB phase on surface with (1 1 1), (2 1 0), (1 0 1) and (1 1 1) planes. SEM cross-sectional investigations show that double-phase boride layer existence from surface to inside of substrate. The structural compositions of layers consist of boron rich phase (FeB) and iron rich phase (Fe2B), respectively. Surface roughness value of samples is important parameter for micro-indentation test with Dynamic Ultra Micro Hardness Tester. After diffusion controlled boriding process, material surface roughness can be high for micro-indentation test. So, surface polishing process is applied for decreasing roughness of FeB layers. Surface roughness values of 2 h, 4 h and 6 h borided SAE 1020 and SAE 1040 quality steel were decreased from 0.9 μm to 0.05 μm by polishing process. Mechanical properties of layers were examined by Shimadzu Dynamic Ultra-microhardness test machine for estimating Young's modulus due to load-unload sensing analysis and in addition to mechanical investigation hardness-depth curves of the layer were obtained for estimating indentation depth and load dependency of mechanical properties. Load depended elastic modulus (125-624 GPa) and hardness (17-33 GPa) were obtained at 80 mN, 160 mN, 320 mN and 640 mN applied peak loads depending on boriding process time. Fracture toughness properties of FeB surface layers were calculated by Vickers Fracture Toughness method for 1 N applied peak load with measuring crack length after loading stage was finished. © 2007 Elsevier B.V. All rights reserved.Item Production of ferroboron powders by solid boronizing method(2010) Sahin S.; Meric C.; Saritas S.Ferroboron is an iron-boron alloy containing 10-20% of boron by weight. Commercial ferroboron production is made by two main processes: carbothermic reaction and aluminothermic reaction. Ferroboron also occurs in steel surfaces due to boronizing, which is applied to increase surface hardness in steel. Boronizing is a thermo-chemical surface hardening treatment. The ferroboron phases like Fe2B, FeB form by diffusing of boron element into iron. These phases are very hard, wear strengths are high, and friction coefficients are low. In this study, ferroboron powder was obtained by boronizing ASC 100.29 iron powder that was used widely in powder metallurgy area. Solid boronizing method was preferred due to its advantages in applications and Ekabor-HM powder was used as the boronizing agent. The 80% ASC 100.29 and 20% Ekabor HM were mixed homogeneously and subjected to boronizing at 850-950 °C for 1-6 h. Formation and development of ferroboron phase on the samples was determined by metallographic studies depending on various treatment conditions. The X-ray diffraction analysis revealed that the Fe2B phase did form but FeB phase did not. Micro hardness distributions were measured on the powder grains. Eighteen GPa hardness was measured at Fe2B phase obtained by boronizing while hardness of non-boronized iron powders was 1.06 GPa. The thickness of ferroboron layer formed by boronizing changed with boronizing conditions. The thickness of ferroboron layer increased with boronizing temperature or boronizing time. Depending upon processing parameters, ferroboron layers was formed partially or throughout ferrous powder structure. Since boronizing can be applied to iron powders having any size or shape, ferroboron production with required shape and size is possible. Finally, a new method, namely solid boronizing method, was developed in ferroboron powder production. © 2010 The Society of Powder Technology Japan.Item Depression and anxiety levels in woman under follow-up for breast cancer: Relationship to coping with cancer and quality of life(2010) Karakoyun-Celik O.; Gorken I.; Sahin S.; Orcin E.; Alanyali H.; Kinay M.Aim The relation of anxiety and depression levels with characteristics of coping with the disease and quality of life were evaluated in women under follow-up for breast cancer. Materials and Methods Patients who had presented to the breast cancer polyclinics for follow-up were evaluated. The Beck Depression and the State-Trait Anxiety inventories were used in the evaluation of depression and anxiety levels. In order to evaluate their power to cope with cancer, the patients were questioned for a social support network. EORTC QLQ-C30 and QLQ-BR23 questionnaires were applied for quality of life evaluations. Results There were 23 (19%) patients with depression; 3 (2.5%) with grade I anxiety, 94 (77%) grade II, and 23 (19%) grade III anxiety, respectively. Depression and anxiety levels were affected by the following parameters: being unaccompanied by spouse for hospital follow-ups (P < 0.0001); request to get help by a psychologist (P = 0.02); presence of a person to share their problems (P < 0.0001); and using an alternative treatment (P = 0.04). In the quality of life evaluations, difficulty in sleeping, emotional status, fatigue, and body appearance were related with both depression and anxiety (P < 0.05 for all), whereas physical function (P = 0.002), role performance (P = 0.005), cognitive condition (P < 0.0001), social position (P < 0.0001), pain (P < 0.0001), general health (P < 0.0001), treatment methods (P = 0.001), future anxiety (P < 0.0001), and arm symptoms (P = 0.001) were negatively affected in patients with depression. Conclusion High depression and anxiety levels in patients under follow-up for breast cancer influence the coping with cancer and quality of life adversely. © 2009 Humana Press Inc.Item Microwave-Assisted hydrodistillation of essential oil from rosemary(Springer, 2014) Karakaya S.; El S.N.; Karagozlu N.; Sahin S.; Sumnu G.; Bayramoglu B.Effects of microwave assisted hydrodistillation (MAHD) and conventional hydrodistillation (HD) methods on yield, composition, specific gravity, refractive index, and antioxidant and antimicrobial activities of essential oil of Rosmarinus officinalis L were studied. The main aroma compounds of rosemary essential oil were found as 1,8- cineole and camphor. Trolox equivalent antioxidant capacity (TEAC) values for essential oils extracted by MAHD and HD were 1.52 mM/ml oil and 1.95 mM/ml oil, respectively. DPPH radical scavenging activity of the oils obtained by MAHD and HD were found as 60.55% and 51.04% respectively. Inhibitory effects of essential oils obtained by two methods on linoleic acid peroxidation were almost the same. Essential oils obtained by two methods inhibited growth of sherichia coli O157:H7, Salmonella typhimurium NRRLE 4463 and Listeria monocytogenes Scott A with the same degree. However, inhibitory activity of essential oil obtained by MAHD on Staphylococcus aureus 6538P was stronger than that of obtained by HD (p<0.05). © Association of Food Scientists & Technologists (India) 2011.Item Heat treatment effects on mechanical properties of atmospheric plasma sprayed FexB coatings on Al substrate(2014) Culha O.; Sahin S.; Ozdemir I.; Toparli M.In this work, we draw attention to determination of heat-treatment effects on mechanical properties of atmospheric plasma sprayed (APS) FexB coatings on aluminum substrates by micro-indentation technique. With this regard, iron boride powders of Fe-18.8B-0.2C-0.5Si-0.8Al (wt.%) were deposited onto Al substrates by APS in order to improve the mechanical properties of Al surface. As-sprayed coatings are composed of mainly FexB and iron matrix supersaturated with boron owing to the rapid solidification of molten droplets flattened on a substrate. It was observed that APS coatings exhibited characteristic wavy layered structure having porosity, inclusions, and semi-melted particles. The postfurnace treatment of APS coatings was carried out at temperatures ranged from 450 to 550°C in an argon atmosphere. The post-treatment applied for APS deposits led to increase in hardness of 40% without showing cracks. Furthermore, micro-mechanical properties of Fe xB coatings were examined by Shimadzu Dynamic Ultra-Microhardness Tester for estimating Young's modulus and hardness due to load-unload sensing analysis by applying different loads such as 160, 320, and 640 mN to determine load and indentation depth dependency of APS FexB on Al substrate for each samples, in details. © 2011, Society for Experimental Mechanics.Item Predictive value of the TRACK questionnaire as a measure of asthma control in preschool aged children(Korean Academy of Asthma, Allergy and Clinical Immunology, 2014) Yilmaz O.; Turkeli A.; Sahin S.; Yuksel H.Assessment of asthma control in preschool children is important for therapeutic decisions. Aim of this study was to evaluate the predictive value of TRACK questionnaire scores for subsequent clinical parameters and to investigate the validity and reliability of the Turkish version of the TRACK questionnaire. We enrolled 100 children with asthma aged 4 years or younger in this cohort study. We recorded sociodemographic characteristics and clinical severity parameters. A pediatric allergist filled in the asthma severity scale and the caregiver of the child filled in the TRACK questionnaire. We called in the children again at the end of one month and recorded the same parameters and administered TRACK again. Uncontrolled asthma was defined as a TRACK score below 80. According to the TRACK score, 65% of the children had controlled asthma initially while at the end of the study 64.1% had controlled asthma. At the beginning of the study, all clinical parameters were worse in children with uncontrolled asthma according to TRACK score. Similarly, other objective clinical parameters during the following one month period were worse in children with initial uncontrolled asthma. Cronbach's alpha score for the TRACK questionnaire was 0.84. Turkish TRACK questionnaire is a valid and reliable tool that is predictive of short term asthma prognosis. © Copyright The Korean Academy of Asthma, Allergy and Clinical Immunology.Item Hardness profiles of Sn-3.0Ag-0.5Cu-TiO2 composite solder by nanoindentation(Elsevier Ltd, 2016) Yahaya M.Z.; Ani F.C.; Samsudin Z.; Sahin S.; Abdullah M.Z.; Mohamad A.A.Improvement of the hardness values of Sn-3.0Ag-0.5Cu-TiO2 composite solders with different TiO2 weight percentages was evaluated by nanoindentation. The composite solders were prepared by ball milling of Sn-3.0Ag-0.5Cu solder with TiO2 nanoparticles at 300 rpm for 10 min prior to printing and reflowing. Structural analysis indicated that the TiO2 nanoparticles were successfully blended into the Sn-3.0Ag-0.5Cu solder. Finer Cu6Sn5 and Ag3Sn phases were observed in the composite solder micrographs. The optimum hardness of 1.775 GPa was obtained for the composite solders with a TiO2 content of 1 wt%. A further increment of the TiO2 content to 1.5 wt% significantly reduced the hardness value to 1.677 GPa. The hardness profiles were established based on the specific measurement pattern obtained from the nanoindentation. The mechanism of the influence of TiO2 nanoparticles on the refinement of the intermetallic phases and improvement of the hardness value is also presented. © 2016 Elsevier B.V.Item Best Practice Recommendations for Stroke Patients with Dysphagia: A Delphi-Based Consensus Study of Experts in Turkey-Part II: Rehabilitation(Springer, 2021) Umay E.; Eyigor S.; Ertekin C.; Unlu Z.; Selcuk B.; Bahat G.; Karahan A.Y.; Secil Y.; Gurcay E.; Kıylioglu N.; Keles B.Y.; Giray E.; Tikiz C.; Gezer I.A.; Yalıman A.; Sen E.I.; Vural M.; Saylam G.; Akaltun M.S.; Sari A.; Alicura S.; Karaahmet F.; Inanir M.; Demirhan A.; Aydeniz B.; Bilgilisoy M.; Yuksel A.; Ozcete Z.A.; Calik Y.; Alemdaroglu E.; Keskin D.; Sahin S.; Oztekin M.F.; Sezgin B.; Karaahmet O.Dysphagia is one of the most common and important complications of stroke. It is an independent marker of poor outcome following acute stroke and it continues to be effective for many years. This consensus-based guideline is not only a good address to clinical questions in practice for the clinical management of dysphagia including management, diagnosis, follow-up, and rehabilitation methods, but also includes detailed algorithms for these topics. The recommendation paper has been written by a multidisciplinary team and offers 117 recommendations for stroke patients with dysphagia. While focusing on management principles, diagnosis, and follow-up in the 1st part (45 items), rehabilitation details were evaluated in the 2nd part (72 items). © 2021, Springer Science+Business Media, LLC, part of Springer Nature.Item The Impact of the COVID-19 Lockdown on the Quality of Life in Chronic Neurological Diseases: The Results of a COVQoL-CND Study(S. Karger AG, 2021) Sahin S.; Karsidag S.; Cinar N.; Ates M.F.; Demir S.; Eren F.; Neyal A.; Kisabay Ak A.; Bora Tokcaer A.; Erkoc Ataoglu E.; Akkaya S.N.; Aciman Demirel E.; Koc F.; Ozturk S.; Ekmekyapar Firat Y.; Okluoglu T.; Togrol E.; Erdemoglu A.K.; Ergin N.; Sayin R.; Demir A.; Yilmaz S.E.Background: Coronavirus disease 2019 (COVID-19) pandemic and lockdown period may induce an impairment in quality of life (QoL), disruption in treatment (DIT), and posttraumatic stress disorder (PTSD) in chronic neurological diseases (CNDs). To reach this information, a multicenter, cross-sectional study (COVQoL-CND) was planned. Parkinson's disease (PD), headache (HA), multiple sclerosis (MS), epilepsy (EP), polyneuropathy (PNP), and cerebrovascular disease (CVD) were selected as the CND. Methods: The COVQoL-CND study includes demographic data, the World Health Organization Quality of Life short form (WHOQOL-BREF), and Impact of Event Scale-Revised (IES-R) forms. Results: The mean age of a total of 577 patients was 49 ± 17 (19-87 years), and the ratio of female/male was 352/225. The mean age of patients with PD, HA, MS, EP, PNP, and CVD were 65 ± 11, 39 ± 12, 38 ± 10, 47 ± 17, 61 ± 12, and 60 ± 15 years, respectively. The IES-R scores were found to be higher in the younger group, those with comorbid disease, contacted with CO-VID-19 patients, or diagnosed with COVID-19. In the group with a high IES-R score, the rate of DIT was found to be high. IES-R scores were negatively correlated with QoL. IES-R total scores were found highest in the CVD group and lowest in the PD group. The ratio of DIT was found highest in the PNP group and the lowest in the EP group. Contact with CO-VID-19 patients was high in the EP and HA group. Conclusions: The results of the COVQoL-CND study showed that lockdown causes posttraumatic stress and deterioration in the QoL in CND. © 2021Item The skills of defibrillation practice and certified life-support training in the healthcare providers in Turkey(Wiley-Hindawi, 2021) Derinoz-Guleryuz O.; Uysal-Yazici M.; Udurgucu M.; Karacan C.; Akça H.; Ongun E.A.; Ekinci F.; Duman M.; Akça-Çaglar A.; Vatansever G.; Bilen S.; Uysalol M.; Akcan-Yıldız L.; Saz E.U.; Bal A.; Piskin E.; Sahin S.; Kurt F.; Anil M.; Besli E.; Alakaya M.; Gültekingil A.; Yılmaz R.; Temel-Koksoy O.; Kesici S.; Akcay N.; Cebisli E.; Emeksiz S.; Kılınc M.A.; Köker A.; Çoban Y.; Erkek N.; Gurlu R.; Eksi-Alp E.; Apa H.; Kalkan G.; Azapagası E.; Yener N.; Sarac-Sandal O.; Horoz O.O.; Öztürk A.; Tuygun N.; Özdemir İ.; Göktuğ A.; Gökulu G.; Gümüs S.; Teksam O.; Turan C.; Zengin N.; Kardeş H.; Bozan G.; Ünal B.; Bardak S.; Arslanköylü A.E.; Yorulmaz A.; Celegen M.; Sevketoglu E.; Dursun O.; Perk O.; Başpınar O.; Akgul F.Aim of the study: Successful cardiopulmonary resuscitation and early defibrillation are critical in survival after in- or out-of-hospital cardiopulmonary arrest. The scope of this multi-centre study is to (a) assess skills of paediatric healthcare providers (HCPs) concerning two domains: (1) recognising rhythm abnormalities and (2) the use of defibrillator devices, and (b) to evaluate the impact of certified basic-life-support (BLS) and advanced-life-support (ALS) training to offer solutions for quality of improvement in several paediatric emergency cares and intensive care settings of Turkey. Methods: This cross-sectional and multi-centre survey study included several paediatric emergency care and intensive care settings from different regions of Turkey. Results: A total of 716 HCPs participated in the study (physicians: 69.4%, healthcare staff: 30.6%). The median age was 29 (27-33) years. Certified BLS-ALS training was received in 61% (n = 303/497) of the physicians and 45.2% (n = 99/219) of the non-physician healthcare staff (P <.001). The length of professional experience had favourable outcome towards an increased self-confidence in the physicians (P <.01, P <.001). Both physicians and non-physician healthcare staff improved their theoretical knowledge in the practice of synchronised cardioversion defibrillation (P <.001, P <.001). Non-certified healthcare providers were less likely to manage the initial doses of synchronised cardioversion and defibrillation: the correct responses remained at 32.5% and 9.2% for synchronised cardioversion and 44.8% and 16.7% for defibrillation in the physicians and healthcare staff, respectively. The indications for defibrillation were correctly answered in the physicians who had acquired a certificate of BLS-ALS training (P =.047, P =.003). Conclusions: The professional experience is significant in the correct use of a defibrillator and related procedures. Given the importance of early defibrillation in survival, the importance and proper use of defibrillators should be emphasised in Certified BLS-ALS programmes. Certified BLS-ALS programmes increase the level of knowledge and self-confidence towards synchronised cardioversion-defibrillation procedures. © 2021 John Wiley & Sons LtdItem Epidemiological, Clinical, and Laboratory Features of Children With COVID-19 in Turkey(Frontiers Media S.A., 2021) Karbuz A.; Akkoc G.; Bedir Demirdag T.; Yilmaz Ciftdogan D.; Ozer A.; Cakir D.; Hancerli Torun S.; Kepenekli E.; Erat T.; Dalgic N.; Ilbay S.; Karaaslan A.; Erdeniz E.H.; Aygun F.D.; Bozdemir S.E.; Hatipoglu N.; Emiroglu M.; Sahbudak Bal Z.; Ciftci E.; Bayhan G.I.; Gayretli Aydin Z.G.; Ocal Demir S.; Kilic O.; Hacimustafaoglu M.; Sener Okur D.; Sen S.; Yahsi A.; Akturk H.; Cetin B.; Sutcu M.; Kara M.; Uygun H.; Tural Kara T.; Korukluoglu G.; Akgun O.; Üstündağ G.; Demir Mis M.; Sali E.; Kaba O.; Yakut N.; Kılıc O.; Kanik M.K.; Cetin C.; Dursun A.; Cicek M.; Kockuzu E.; Sevketoglu E.; Alkan G.; Guner Ozenen G.; İnce E.; Baydar Z.; Ozkaya A.K.; Ovali H.F.; Tekeli S.; Celebi S.; Cubukcu B.; Bal A.; Khalilova F.; Kose M.; Hatipoglu H.U.; Dalkiran T.; Turgut M.; Basak Altas A.; Selcuk Duru H.N.; Aksay A.; Saglam S.; Sari Yanartas M.; Ergenc Z.; Akin Y.; Duzenli Kar Y.; Sahin S.; Tuteroz S.K.; Bilen N.M.; Ozdemir H.; Senoglu M.C.; Pariltan Kucukalioglu B.; Besli G.E.; Kara Y.; Turan C.; Selbest Demirtas B.; Celikyurt A.; Cosgun Y.; Elevli M.; Sahin A.; Bahtiyar Oguz S.; Somer A.; Karadag B.; Demirhan R.; Turk Dagi H.; Kurugol Z.; Taskin E.C.; Sahiner A.; Yesil E.; Ekemen Keles Y.; Sarikaya R.; Erdem Eralp E.; Ozkinay F.; Konca H.K.; Yilmaz S.; Gokdemir Y.; Arga G.; Ozen S.; Coksuer F.; Vatansever G.; Tezer H.; Kara A.Objectives: The aim of this study is to identify the epidemiological, clinical, and laboratory features of coronavirus disease 2019 (COVID-19) in children. Methods: A retrospective study was conducted by pediatric infectious disease specialists from 32 different hospitals from all over Turkey by case record forms. Pediatric cases who were diagnosed as COVID-19 between March 16, 2020, and June 15, 2020 were included. Case characteristics including age, sex, dates of disease onset and diagnosis, family, and contact information were recorded. Clinical data, including the duration and severity of symptoms, were also collected. Laboratory parameters like biochemical tests and complete blood count, chest X-ray, and chest computed tomography (CT) were determined. Results: There were 1,156 confirmed pediatric COVID-19 cases. In total, male cases constituted 50.3% (n = 582) and females constituted 49.7% (n = 574). The median age of the confirmed cases was 10.75 years (4.5–14.6). Of the total cases, 90 were younger than 1 year of age (7.8%), 108 were 1–3 years of age (9.3%), 148 were 3–6 years of age (12.8%), 298 were 6–12 years of age (25.8%), 233 were 12–15 years of age (20.2%), and 268 cases were older than 15 years of age (23.2%). The most common symptom of the patients at the first visit was fever (50.4%) (n = 583) for a median of 2 days (IQR: 1–3 days). Fever was median at 38.4°C (38.0–38.7°C). The second most common symptom was cough (n = 543, 46.9%). The other common symptoms were sore throat (n = 143, 12.4%), myalgia (n = 141, 12.2%), dyspnea (n = 118, 10.2%), diarrhea (n = 112, 9.7%), stomachache (n = 71, 6.1%), and nasal discharge (n = 63, 5.4%). When patients were classified according to disease severity, 263 (22.7%) patients were asymptomatic, 668 (57.7%) patients had mild disease, 209 (18.1%) had moderate disease, and 16 (1.5%) cases had severe disease. One hundred and forty-nine (12.9%) cases had underlying diseases among the total cases; 56% of the patients who had severe disease had an underlying condition (p < 0.01). The need for hospitalization did not differ between patients who had an underlying condition and those who do not have (p = 0.38), but the need for intensive care was higher in patients who had an underlying condition (p < 0.01). Forty-seven (31.5%) of the cases having underlying conditions had asthma or lung disease (38 of them had asthma). Conclusions: To the best of our knowledge, this is one of the largest pediatric data about confirmed COVID-19 cases. Children from all ages appear to be susceptible to COVID-19, and there is a significant difference in symptomatology and laboratory findings by means of age distribution. © Copyright © 2021 Karbuz.