Browsing by Author "Şahin S."
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Item Production and characterisation of Fe2B powders; [Fe2B tozlarinin üreti̇m ve karakteri̇zasyonu](1999) Şahin S.; Meriç C.In this study, Boronizing, which is used as a surface hardening method against wear and corrosion, is applied to iron powder commercial known as ASC 100.29. In boronizing process with solid boron yielding substances, powder with a commercial name Ekabor-HM is used boronizing material. The effects of temperature, time and particule size on boronizing iron powders are investigated and depending upon process conditions Fe2B phase is obtained in whole or a cerain part of iron powders. The microstructure and microhardness analysis of bornized iron powders are made.Item Investigation of joining steel hard metal tips used in boring machines; [Sondaj matkaplarinda kullanilan sert metal uç-çeli̇k çi̇fti̇ni̇n bi̇rleşebi̇li̇rli̇ǧi̇ni̇n i̇ncelenmesi̇](1999) Uzkut M.; Köksal N.S.; Şahin S.The use of boring machines under highly varying working conditions for long periods requires a successful joining of material couples. If the joining is not performed successfully, hard metal tips will shorten the life of the boring machine by breaking off from the steel body. In addition, these broken hard metal tips deposited in the bore will affect later boring work negatively. For this reason, the quality of joining has a great significance from the economy and efficiency point of view. In this study, joining by brazing of 0.4% C steel with 9% Co bonder mixed wolfram carbide based hard metal tip used in boring machines is investigated. Joining by brazing of wolfram carbide based hard metal tip with 0.4% C steel is made under suitable temperature and pressure using suitable dekapan. The microhardness and metalographic investigation of steel, braze, and hard metal tip has been done in the joining region. In the metalographic investigations, it has been observed that, in the internal structure and hardness values of solder, diffusion from steel to solder and from solder to steel occurs. Also element diffusion from hard metal tip to solder layer takes place.Item Effect of production parameters on wear behavior in Al/SiCp composites produced by the P/M method; [T/M yöntemi ile üretilmiş Al-SiC p kompozitlerde üretim parametrelerinin aşinma davranişina etkisi](2002) Şahin S.; Özdemir I.; Ünlü B.S.In this study, Al based composites reinforced with SiCp were produced by the P/M method. In manufactured composites proportions of reinforced SiCp were chosen to be 5%, 10%, 15% and 20% by weight. Experimental sample of Al/SiCp composites which are 35mm in diameter and 10mm in lenght were pressed at pressures of 500MPa and 350MPa and the composites were sintered an argon gas environment at 600°Cfor period of 30 min. Density and hardness test of produced composites were performed their wesr behaviours were investigated. Wear test were carried out using a pin-on disc type tribometer with rubbing against 600 grit SiC abrasive paper. It was observed that the increase of compression pressure and reinforing fraction improved wear resistance of the composites.Item Effects of boronizing process on the surface roughness and dimensions of AISI 1020, AISI 1040 and AISI 2714(2009) Şahin S.In this study, the effects of boronizing treatment on material's dimensional changes and surface roughness were investigated. The parameters chosen were substrate material composition, surface roughness before boronizing treatment, and boronizing time. The AISI 1020, AISI 1040 and AISI 2714 were chosen as substrate materials whereas Ekabor I was selected as boronizing powder. Materials were boronized at 900 °C by using a solid boronizing method for 2 or 4 h. The gradual growth of boride layer on the surface, dimensional changes and their effects on surface roughness were investigated. Variations in topographical surface roughness were determined by SEM. With the boronizing treatment, dimensional increases of the material's were observed. The dimensional increase was one fifth of boride layer thickness for AISI 1020 or AISI 1040, whereas it was one third of boride layer thickness for AISI 2714. Boronizing treatment had also a significant effect on surface roughness of materials. A "threshold roughness" term was defined in our study. This term is a surface roughness value for smooth surfaces, which received boronizing treatment. For the same material and with the same boronizing conditions, the threshold roughness value was achieved after boronizing, when surface roughness of material was below the threshold roughness value, before boronizing was applied. However, when surface roughness of a material was above that threshold roughness value, surface roughness value decreased with boronizing treatment. The thereshold roughness value depended on substrate material composition and boronizing parameters. © 2008 Elsevier B.V. All rights reserved.Item Wear behavior of plasma-sprayed Al-12Si/SiC composite coatings under dry and water-lubricated sliding(2009) Akgun S.; Şahin S.; Ustel F.Powders of Al-12Si with 25 and 50wt% SiC particles were ball-milled in a conventional rotating ball mill with alumina balls for 2h. The milled powders were plasma-sprayed onto aluminum and stainless steel substrates to obtain Al matrix composites with high SiC weight fraction. The microstructure characteristics of the sprayed composites were investigated by metal microscopy. Surface roughness, coating thickness and microhardness were measured. Microhardness values increased when the amount of SiC particles in Al-12Si coatings increased. The wear behavior of the coatings under dry-sliding and water-lubricated sliding with stainless steel counter material was studied using ball on disc for 10kN. Wear surfaces were investigated with scanning electron microscopy (SEM). Increasing SiC content of coatings increased the wear resistance. The highest wear resistance in coatings was observed in the coating having 50% SiC.Item A study for boronizing process within nonextensive thermostatistics(Association for Scientific Research, 2010) Kayacan O.; Şahin S.; Taştan F.In this study, diffusion mechanism of the boronizing process of AISI 1040 has been investigated. A nonlinear diffusion equation, which was proposed earlier, has been employed and compared with the experimental data. An interesting property of the diffusion equation used here is that it establishes a connection between the diffusion process and nonextensivity. The theoretical model also exhibits a possible connection between the exponents appeared in the differential equation and the entropic index. In this manner, the possible effects of nonextensivity on the boronizing process have been shown theoretically. We believe that a diffusion equation based on the nonextensive formalism is first applied to the boronizing process in literature. © Association for Scientific Research.Item Antioxidant and antimicrobial activities of essential oils obtained from Oregano (Origanum vulgare ssp. hirtum) by using different extraction methods(2011) Karakaya S.; El S.N.; Karagözlü N.; Şahin S.In this study, antioxidant and antimicrobial activities of essential oils obtained from oregano (Origanum vulgare ssp. hirtum) were determined by using solvent-free microwave extraction (SFME), supercritical fluid extraction, and conventional hydrodistillation (CH) methods. The inhibitory effects on the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical of essential oils obtained from oregano by using SFME and CH were similar. However, essential oil extracted by CH showed greater (2.69μmol/μL of oil) Trolox equivalent antioxidant capacity (TEAC) than oregano oils obtained by SFME (P<.05). The difference between percentage inhibition and TEAC values most probably is due to the fact that undiluted and diluted samples are used in the percentage inhibition assay and the TEAC assay, respectively. TEAC values of oregano essential oils obtained by SFME at different microwave power levels were found to be similar and ranged from 0.72 to 0.84μmol/μL of oil. Essential oils obtained by CH and SFME at different microwave powers inhibited the survival of Listeria monocytogenes, Salmonella typhimurium, and Escherichia coli O157:H7, whereas survival of Staphylococcus aureus was not influenced. In addition, oregano oil obtained by SFME at 40% power level did not show any inhibitory effect on E. coli O157:H7. © Copyright 2011, Mary Ann Liebert, Inc.Item Investigation of the influence of the pre-aging process on the hardness of 6082 and 7075 aluminum alloys(Carl Hanser Verlag, 2012) Şahin S.; Durmu H.; Yüksel N.; Manisa M.In this study, the effect of pre-aging time and temperature on mechanical properties of aluminium alloys 6082 and 7075 has been investigated. Pre-aging has been applied at 50, 60, 70 and 80 °C for 24, 72, 144 hours after solution treatment process at 560 °C for 1 hour. Then these samples have been subjected to an aging process at 180 °C and 125 °C. The hardness of samples has been measured during aging process regularly. Eventually, it was determined that if pre-aging process is performed at low temperature, an increase of hardness occurs and hardness decreases with increasing temperature during aging. © Carl Hanser Verlag, München.Item The effect of the retrogression process on the wear behaviour of a 7075 aluminium alloy(Carl Hanser Verlag, 2012) Durmus H.; Uzun R.O.; Şahin S.; Yüksel N.Retrogression and re-aging (RRA) process are applied in an attempt to enhance mechanical properties and corrosion resistance of 7075 aluminium alloys. In this study, retrogression and re-aging process have been applied to a 7075 aluminium alloy at 170 °C for 5, 40, 80 min and wear resistance of RRA applied samples have been investigated by ball-on-disc wear test apparatus. Sliding distance has been chosen as 300 meters. Re-aging procedure has been carried out at 125 °C for 10, 20 and 30 hours. Minimum wear loss has been obtained by retrogression for 40 min and aging for 30 hours. © Carl Hanser Veriag, München.Item Interpratation and adaptation of dermoscopic terminology to our language: Consensus report of the turkish society of dermatology dermoscopy working group; [Dermoskopik terminolojinin dilimize uyarlanmasi{dotless}: Türk dermatoloji derneǧi dermoskopi çali{dotless}şma grubu uzlaşi{dotless}si{dotless}](2013) Özdemir F.; Karaarslan I.K.; Türk B.G.; Şahin S.; Şahin M.T.; Oǧuz O.; Öztaş M.O.; Arca E.; Mansur T.; Anil A.; Karabulut; Kaçar N."Dermoscopic Terminology Consensus Meeting" was held at Ege University Medical Faculty Dermatology Department on the 24th of February in 2012 with the aim of establishing a common language in the translation of the dermoscopic terminology in English literature into Turkish. In this article, the Turkish terminology in which the consensus was reached at that meeting is presented together with the definitions and representative images as a dictionary. © 2013 by Turkish Society of Dermatology.Item Wear behavior-hardness-microstructure relation of Fe-Cr-C and Fe-Cr-C-B based hardfacing alloys(Elsevier Ltd, 2014) Yüksel N.; Şahin S.The aim of this study is the investigation of the effect of ferroboron and the amount of powder mixture (ferroboron. +. ferrochromium) on wear resistance of Iron (Fe)-Chromium (Cr)-Carbon (C) based hardfacing alloys. Powder mixture, consisting of ferrochromium (FeCr) and ferroboron (FeB), was added to massive wire during welding process. Hardfaced layers were obtained by three different powder mixtures and two different powder/massive wire proportions. Hardfacing was applied to AISI 1020 steel substrate by open arc welding. Hardness test, Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) analysis, dry sand/rubber wheel abrasion test were executed. Test results showed that increasing ferroboron content and increasing powder mixture amount enhanced the wear resistance. © 2014 Elsevier Ltd.Item Effects of ferroboron and ferrochromium powder addition on abrasive wear resistance of fe-based hardfacing coatings(Carl Hanser Verlag, 2014) Yüksel N.; Şahin S.Ferrochromium is used in hardfacing alloys as carbide former. In this study, ferroboron was used with ferrochromium to investigate the effect on microstructure and wear resistance. Five different hardfacing alloys (50 % massive welding wire + 50 % powder mixture) were produced by open arc welding on AISI 1020 steel. Microstructure, SEM and XRD analysis, hardness test, and dry sand/rubber wheel abrasion test were carried out. According to the test results, as the amount of ferroboron increased, wear rate decreased. Minimum wear rate was obtained in 100 % ferroboron powder added sample. © Carl Hanser Verlag GmbH & Co. KG.Item Wear behavior of Al/SiC/graphite and Al/FeB/graphite hybrid composites(Institute of Metals Technology, 2014) Şahin S.; Yüksel N.; Durmuş H.; Irizalp S.G.Silicon carbide is often the preferred reinforcement in the production of aluminium-powder composites. In this study, aluminium composites were produced with 10 % and 20 % silicon-carbide and ferroboron reinforcements and (0, 0.5, 1 and 1.5) % graphite additions using powder metallurgy. The effects of the reinforcement type, the amount and the graphite content on the wear resistance were investigated. When compared with the unreinforced aluminium sample, it was clear that the increasing reinforcement increased the wear resistance. It was determined that the increasing graphite content negatively affects the wear resistance. The sample including 20 % ferroboron and 0 % graphite showed the minimum wear rate.Item Wear behavior of fe-c-cr based hardfacing alloys dependent on ferrovanadium and ferrotungsten addition(Carl Hanser Verlag, 2014) Kapali G.; Şahin S.; Yüksel N.; Sargin F.; Yaman B.The aim of this study is to investigate the effect of vanadium and tungsten on wear behavior of Fe-C-Cr based hardfacing alloys. The wear behavior of hard-facing layers was determined by dry sand/rubber wheel abrasion tests according to ASTM G-65. The results of the abrasion tests were interpreted by metallographic examinations, SEM and EDX analyses as well as hardness measurements. According to the results of the experimental studies, the effect of W and V addition was discussed. © Carl Hanser Verlag GmbH & Co.Item The attitudes of medical students toward the elderly; [Tip fakültesi öğrencilerinin yaşlilara karşi tutumlari](Geriatrics Society, 2015) Elbi H.; Altan S.; Rahman S.; Cengiz Özyurt B.; Şahin S.; Çam F.S.Introduction: Health workers must be prepared for the changes and developments due to the ever-increasing proportion of elderly individuals within the general population. This study aimed to identify the general attitudes of students of the Faculty of Medicine of Celal Bayar University (CBU) toward senility and evaluate differences in the attitudes of students at different stages of medical education. Materials and Method: This study was conducted between October and December 2014 and included a total of 406 students attending the Faculty of Medicine of the CBU. A questionnaire form composed of three sections was used to collect data. Results: The age range of study participants was 18-27 years (average age, 21.04 years) 60.8% were females, and 91.4% had a nuclear family structure. When assessing overall UCLA scores according to the stage of medical education, the average scores of first-year students were found to be higher than other year groups. The results of the UCLA questionnaire demonstrated significantly higher overall scores concerning attitudes toward older persons in female students compared with male students. No significant differences in KOGAN questionnaire scores concerning attitudes toward older people were observed between male and female students. Conclusion: The findings of the present study indicate that attitudes toward the elderly change negatively as students progress through medical education. In addition, female students had more positive attitudes toward elderly patients than male students. Considering the expectations from the healthcare providers of the elderly population, who are more fragile compared to normal individuals, it should be envisaged that the responsibilities of physicians have increased. © 2015, Geriatrics Society. All rights reserved.Item Predictors of new-onset atrial fibrillation after st-segment elevation myocardial infarction in the elderly; [Yaşli Hastalarda St Segment Yükselmeli Miyokard Infarktüsü Sonrasi Yeni Gelişen Atriyal Fibrilasyonun Gelişimini Öngördürücü Etkenler](Nobelmedicus, 2015) Kartal E.; Elbi H.; Alp A.; Şahin S.; Özbakkaloğlu M.; Özdoğan Ö.Objective: The predictors and outcomes of new-onset atrial fibrillation (AF) were evaluated among elderly patients with acute ST elevation myocardial infarction (STEMI). Material and Method: Patients with STEMI who are older than 65 years were evaluated for new-onset AF and its complications. Patients with a previous history of AF and those found in AF at the time of admission were excluded. Results: Of the 102 patients with STEMI, AF was not observed in 74 patients (Group I) and was observed in 28 patients (Group II) during hospitalization. Those 28 patients with AF were further divided into two subgroups according to the onset time of AF (early <24 hours and late >24 hours). Anterior MI was observed in 49% of patients in Group I and 71.4% of patients in Group II (p<0.05). In late onset AF group; pulse rate, systolic and diastolic blood pressure were significantly higher than Group I at admission to the hospital (p<0.05). All patients in Group II had higher Killip class and TIMI risk scores than Group I patients (p<0.05). Left ventricular ejection fraction was 30.4±4.0% in the late onset group and 44.4±8.8% in Group I (p<0.05). There was a significant difference in mortality rate among groups during hospitalization period; 36% in Group II, 9% in Group I (p<0.05). Conclusion: AF is especially seen in elderly female patients with anterior MI and higher Killip Class. It is associated with higher rates of in-hospital mortality. Particularly, lateonset AFs are associated with lower LVEFs in older patients with STEMI and could be predictors of in hospital mortality. © Nobel İlaç AŞ.Item The curriculum of social studies education and world citizenship: From perspective of prospective teachers; [Sosyal bilgiler eğitimi programı ve dünya vatandaşlığı: Öğretmen adaylarının perspektifinden](Hacettepe University, 2016) Şahin M.; Şahin S.; Göğebakan-Yildiz D.The primary purpose of the study is to analyze the relationships between “Inclusion of the concept of world citizenship in Social Studies Education Program and Practices (SSEPP) and “world citizenship competency perceptions (WCCP)” of prospective SSE teachers. This is a relational screening study model. “World Citizenship Scale in SSEPP” and “World Citizenship Competency Perception Scale” that were developed by the researchers were used in the study. A total of 375 fourth grade prospective primary education teachers in SSE departments of randomly selected universities to represent seven different geographical regions of Turkey constituted the sampling of the study. The results showed that prospective teachers evaluated SSEPP at moderate level in terms of its dimensions are “objects”, “content”, “learning situations” and “evaluation” and general of the scale. Likewise, the prospective teachers perceived world citizenship at moderate level. This result points out that even training of world citizen individuals at the SSE program is aimed, this objective couldn’t be adequately reflected in selected texts, intra-class activities and evaluation processes. In addition, prospective teachers who graduated from Anatolian high school and their parent graduated from university had higher perception on the world citizenship. Finally, the findings show that there is a positive and weak relationship between SSEPP and WCCP. © 2016, Hacettepe University. All rights reserved.Item Vitamin D protects against hippocampal apoptosis related with seizures induced by kainic acid and pentylenetetrazol in rats(Elsevier B.V., 2019) Şahin S.; Gürgen S.G.; Yazar U.; İnce İ.; Kamaşak T.; Acar Arslan E.; Diler Durgut B.; Dilber B.; Cansu A.Objectives: The hippocampus is susceptible to damage in patients with epilepsy and in animals with seizures caused by excitotoxic agents. The effect of vitamin D on hippocampal apoptosis related with seizures has not been reported. However, epileptic patients have an increased risk of hypovitaminosis D which is most likely due to the effects of antiepileptic drugs. Therefore, in this study, it was aimed to evaluate the effects of vitamin D on hippocampal apoptosis related with seizures by using pentylenetetrazol (PTZ) and kainic acid (KA) in rats. Methods: Male Sprague Dawley rats, aged 5.5 weeks, were randomly divided into six groups: control, vitamin D, PTZ, KA, PTZ + vitamin D and KA + vitamin D groups. The groups that received vitamin D were given 500 IU/kg of vitamin D daily for two weeks in addition to a standard diet. At the end of this period, PTZ and KA were applied to trigger seizures in the rats in the seizure groups. 24 h after the administration of PTZ and KA, the rats were decapitated. In the hippocampal region, apoptosis was assessed by TUNEL and brain-derived neurotrophic factor (BDNF), Bax, caspase-3 and c-fos activation were evaluated by immunohistochemical method. Results: BDNF level increased while c-fos, Bax and caspase-3 levels decreased (p < 0.0001, in all) in the hippocampal neurons of the groups that were pre-treated with vitamin D before the administration of PTZ and KA, in comparison with the PTZ and KA groups. Vitamin D significantly decreased the number of apoptotic cells in these rats in comparison with the PTZ and KA groups (p < 0.0001). Conclusion: This study indicates that vitamin D has neuroprotective effects on hippocampal apoptosis induced by PTZ and KA in rats. With this study it is suggested that keeping vitamin D levels within normal limits may be beneficial for patients with epilepsy, especially children. © 2018 Elsevier B.V.Item Re-examining the characteristics of pediatric multiple sclerosis in the era of antibody-associated demyelinating syndromes(W.B. Saunders Ltd, 2022) Yılmaz Ü.; Gücüyener K.; Yavuz M.; Öncel İ.; Canpolat M.; Saltık S.; Ünver O.; Çıtak Kurt A.N.; Tosun A.; Yılmaz S.; Özgör B.; Erol İ.; Öztoprak Ü.; Elitez D.A.; Direk M.Ç.; Bodur M.; Teber S.; Anlar B.; Aykol D.; Yıldız E.P.; Yarar C.; Kara B.; Haspolat; İncecik F.; Kutluk G.; Dilber C.; Dundar N.O.; Tan H.; Demir E.; Dursun B.D.; Dilek T.D.; Türkdoğan D.; Yalnızoğlu D.; Akbaş S.; Güleç A.; Yılmaz D.; Ayanoğlu M.; Kanmaz S.; Güngör S.; Öztürk G.; Besen; Haliloğlu G.; Karaca N.B.; Öztürk S.; Yüksel D.; Gürkaş E.; Oktay S.; Serin H.M.; Karadağ M.; Hakkı Akbeyaz İ.; Yiş U.; Polat B.G.; Okan M.S.; Bektaş Ö.; Orgun L.T.; Günbey C.; Per H.; Gültutan P.; Öztürk S.B.; Aksoy E.; Akyüz G.; Tekgül H.; Kürekçi F.; Kurul A.S.H.; Çarman K.B.; Alikılıç D.; Duman Ö.; Kömür M.; Yıldırım M.; Alıcı N.; Gümüş H.; Polat M.; Konuşkan B.; Güngör O.; Mert G.G.; Edizer S.; Mıhçı F.; Öztürk S.T.; Toker R.T.; Arslan M.; Şahin S.; Gencpinar P.; Yıldırım E.; Yüksel E.; Ekici A.; Deniz A.; Yayici Köken Ö.; Okuyaz Ç.; Süt N.Y.; Atasoy E.; Solmaz İ.; Yetkin M.F.; Bilgin N.; Atasever A.K.; Tekin H.G.; Dokurel İ.; Özçelik A.; Aksoy A.; Türköz A.N.; Cavusoglu D.; Özkan M.; Tekin E.; Şahin T.U.; Ünalp A.; Koç H.; Sarıgeçili E.; Sarıtaş S.; Ayça S.; Kayılıoğlu H.; Şenoğlu M.Ç.; Kamaşak T.; Asadova N.; Keskin F.; Karaoğlu P.; İpek R.; Acer H.Background: The discovery of anti-myelin oligodendrocyte glycoprotein (MOG)-IgG and anti-aquaporin 4 (AQP4)-IgG and the observation on certain patients previously diagnosed with multiple sclerosis (MS) actually have an antibody-mediated disease mandated re-evaluation of pediatric MS series. Aim: To describe the characteristics of recent pediatric MS cases by age groups and compare with the cohort established before 2015. Method: Data of pediatric MS patients diagnosed between 2015 and 2021 were collected from 44 pediatric neurology centers across Türkiye. Clinical and paraclinical features were compared between patients with disease onset before 12 years (earlier onset) and ≥12 years (later onset) as well as between our current (2015–2021) and previous (<2015) cohorts. Results: A total of 634 children (456 girls) were enrolled, 89 (14%) were of earlier onset. The earlier-onset group had lower female/male ratio, more frequent initial diagnosis of acute disseminated encephalomyelitis (ADEM), more frequent brainstem symptoms, longer interval between the first two attacks, less frequent spinal cord involvement on magnetic resonance imaging (MRI), and lower prevalence of cerebrospinal fluid (CSF)-restricted oligoclonal bands (OCBs). The earlier-onset group was less likely to respond to initial disease-modifying treatments. Compared to our previous cohort, the current series had fewer patients with onset <12 years, initial presentation with ADEM-like features, brainstem or cerebellar symptoms, seizures, and spinal lesions on MRI. The female/male ratio, the frequency of sensorial symptoms, and CSF-restricted OCBs were higher than reported in our previous cohort. Conclusion: Pediatric MS starting before 12 years was less common than reported previously, likely due to exclusion of patients with antibody-mediated diseases. The results underline the importance of antibody testing and indicate pediatric MS may be a more homogeneous disorder and more similar to adult-onset MS than previously thought. © 2022 European Paediatric Neurology SocietyItem COVID-19 disease in children presenting to the pediatric emergency department: A multicenter study with 8886 cases from Turkey(W.B. Saunders, 2022) Duman M.; Şık N.; Tekşam Ö.; Akça H.; Kurt F.; Çağlar A.A.; Yıldız L.A.; Taşar M.A.; Fidancı İ.; Yayla B.C.C.; Yılmaz D.; Güngör E.; Demir Ş.; Çokuğraş H.; Cebeci S.O.; Önal P.; Saz E.U.; Yurtseven A.; Uysalol M.; Yıldız R.; Gümüş S.; Bal A.; Bayturan S.Ş.; Zengin N.; Atik S.; Çiftdoğan D.Y.; Berksoy E.; Çiçek A.; Şahin S.; Kızıl M.C.; Kara Y.; Apa H.; Ulusoy E.; Kara A.A.; Yesil E.; Erdem M.; Turan C.; Arslanoglu S.; Duyu M.; Besli G.E.; Arslan G.; Oflu A.T.; Çeleğen M.; Buldu E.; Pişkin İ.E.; Kardeş H.; Yılmaz H.L.; Yıldızdaş D.; Gökulu G.; Çay P.; Özer U.; Güleryüz O.D.; Çolak Ö.; Güneysu S.T.Background: The aim was to evaluate the epidemiological, clinical, laboratory, and radiologic data of children with SARS-CoV-2 positivity by polymerase chain reaction (PCR) together with treatment strategies and clinical outcomes and to evaluate cases of multisystem inflammatory syndrome in children (MIS-C) in this population. Methods: This was a multicenter retrospective observational cohort study performed in the pediatric emergency departments of 19 tertiary hospitals. From March 11, 2020, to May 31, 2021, children who were diagnosed with confirmed nasopharyngeal/tracheal specimen SARS-CoV-2 PCR positivity or positivity for serum-specific antibodies against SARS-CoV-2 were included. Demographics, presence of chronic illness, symptoms, history of contact with SARS-CoV-2 PCR-positive individuals, laboratory and radiologic investigations, clinical severity, hospital admissions, and prognosis were recorded. Results: A total of 8886 cases were included. While 8799 (99.0%) cases resulted in a diagnosis of SARS-CoV-2 with PCR positivity, 87 (1.0%) patients were diagnosed with MIS-C. Among SARS-CoV-2 PCR-positive patients, 51.0% were male and 8.5% had chronic illnesses. The median age was 11.6 years (IQR: 5.0–15.4) and 737 (8.4%) patients were aged <1 year. Of the patients, 15.5% were asymptomatic. The most common symptoms were fever (48.5%) and cough (30.7%) for all age groups. There was a decrease in the rate of fever as age increased (p < 0.001); the most common age group for this symptom was <1 year with the rate of 69.6%. There was known contact with a SARS-CoV-2 PCR-positive individual in 67.3% of the cases, with household contacts in 71.3% of those cases. In terms of clinical severity, 83 (0.9%) patients were in the severe-critical group. There was hospital admission in 1269 (14.4%) cases, with 106 (1.2%) of those patients being admitted to the pediatric intensive care unit (PICU). Among patients with MIS-C, 60.9% were male and the median age was 6.4 years (IQR: 3.9–10.4). Twelve (13.7%) patients presented with shock. There was hospital admission in 89.7% of these cases, with 29.9% of the patients with MIS-C being admitted to the PICU. Conclusion: Most SARS-CoV-2 PCR-positive patients presented with a mild clinical course. Although rare, MIS-C emerges as a serious consequence with frequent PICU admission. Further understanding of the characteristics of COVID-19 disease could provide insights and guide the development of therapeutic strategies for target groups. © 2022 Elsevier Inc.