114 research outputs found

    Evaluation of corrosion resistance of Co-Cr alloys fabricated with different metal laser sintering systems

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    PURPOSE. The aim of this study was to evaluate the corrosion resistance of the specimens produced by five different commercial metal laser sintering (MLS) systems with their recommended Co-Cr alloy powders. MATERIALS AND METHODS. The MLS machines and the alloy powders used were, ProX 100-ST2724G (St-Pro), Mysint 100-EOS SP2 (SP2-Mys), EOSINT 270-EOS SP2 (SP2-EOS), SLM 100-Starbond CoS (SB-SLM), and MLab Cusing-Remanium® Star (RS-MLab), respectively. Eight specimens from each group were prepared. Open circuit potential (Eocp) and electrochemical impedance spectroscopy (EIS) measurements of polished surfaces of the specimens were conducted in a three-electrode cell using a potentiostat-galvanostat in Fusayama-Meyer artificial saliva (AS). Specimens from each group were immersed in AS and de-ionized water for seven days. Eocp, charge transfer resistance (Rct) values, and released ions (?g/cm2 x 7d) in different solutions were determined. The specimen surfaces were observed with SEM/EDS. Results were analyzed statistically. RESULTS. Eocp values have shifted to potentials that are more positive over time. Steady-state Eocp values were from high to low as follows, SB-SLM, SP2-Mys, SP2-EOS, RS-MLab, and ST-Pro, respectively. After 60 mins, RS-MLab specimens had the highest Rct value, followed by SP2-Mys, SB-SLM, SP2-EOS, and ST-Pro. In all groups, ion release was higher in AS than that in de-ionized water. CONCLUSION. There were small differences among the corrosion resistances of the Co-Cr alloy specimens produced with MLS systems; meanwhile, the corrosion resistances were quite high for all specimens. © 2020 The Korean Academy of Prosthodontics

    A combined VBM and DTI study of schizophrenia: bilateral decreased insula volume and cerebral white matter disintegrity corresponding to subinsular white matter projections unlinked to clinical symptomatology

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    PURPOSE:Grey matter and white matter changes within the brain are well defined in schizophrenia. However, most studies focused on either grey matter changes or white matter integrity separately; only in limited number of studies these changes were interpreted in the same frame. In addition, the relationship of these findings with clinical variables is not clearly established. Here, we aimed to investigate the grey matter and white matter changes in schizophrenia patients and exhibit the relation of these imaging findings with clinical variables.METHODS:A total of 20 schizophrenia patients and 16 matched healthy controls underwent magnetic resonance imaging to investigate the grey matter and white matter alterations that occur in schizophrenia patients using voxel-based morphometry (VBM) and whole brain voxel-wise analysis of diffusion tensor imaging (DTI) parameters with SPM8, respectively. While the preprocessing steps of VBM were performed with the default parameters of VBM8 toolbox, the preprocessing steps of DTI were carried out using FSL. Additionally, VBM results were correlated with clinical variables.RESULTS:Bilateral insula showed decreased grey matter volume in schizophrenia patients compared with healthy controls (P < 0.01). The opposite contrast did not show a significant difference. Psychiatric scores, duration of illness, and age were not correlated with the decreased grey matter volume of insula in schizophrenia patients. DTI analysis revealed a significant increase in mean, radial, and axial diffusivity, mainly of the fibers of bilateral anterior thalamic radiation and superior longitudinal fasciculus with left predominance, which intersected with bilateral subinsular white matter (P < 0.05).CONCLUSION:Our findings suggest that insula may be the main affected brain region in schizophrenia, which is also well supported by the literature. Our results were independent of disease duration and schizophrenia symptoms. White matter alterations were observed within bilateral anterior thalamic radiation and superior longitudinal fasciculus that intersects with subinsular white matter. Studies with larger sample sizes and more detailed clinical assessments are required to understand the function of insula in the neurobiology of schizophrenia

    Prospective assessment of VI-RADS score in multiparametric MRI in bladder cancer: accuracy and the factors affecting the results

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    PURPOSEWe aimed to investigate the accuracy of Vesical Imaging - Reporting and Data System (VI-RADS) in the detection of muscle-invasive bladder cancer (MIBC) and to determine which factors affect the results of this scoring system.METHODSA prospective data analysis of 80 patients who were detected to have bladder tumor was performed between March 2019 and October 2020. VI-RADS scoring was used to determine the probability of muscle invasion. The scores were compared with pathological results to evaluate the accuracy of the VI-RADS scoring system. Interobserver agreement was assessed by VI-RADS scoring of 20 randomly chosen patients by a different experienced radiologist.RESULTSUsing the VI-RADS scoring system, the sensitivity, specificity, positive predictive value, and negative predictive value of multiparametric magnetic resonance imaging (mpMRI) were 87.5%, 87.5%, 63.6%, and 96.6%, respectively. The interobserver agreement expressed as the interclass correlation coefficient (ICC) was 0.72 (95% CI: 0.44-0.84, P < .001). In addition, the flat appearance of the tumor was an important factor affecting the accuracy of the VI-RADS score (odds ratio: 5.3 [95% CI: 1.1-27.0] and relative risk: 1.87 [95% CI: 1.24-2.82]).CONCLUSIONThe mpMRI, used in conjunction with VI-RADS, has proven to be an effective imaging method for detecting muscle invasion in cases of bladder cancer. VI-RADS scoring system can distinguish whether there is a muscle-invasive and non-muscle invasive bladder cancer with acceptable accuracy. In addition, the flat appearance of the tumor is an important entity that can affect the accuracy of the VI-RADS scoring system

    Okul ve Sınıf Tabanlı Değerlendirmeye Dayalı Öğretmen Kapasitesinin Güçlendirilmesi: Fen Bilimleri Dersi Öğretmen Rehber Kitapçığı

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    Değerli fen bilimleri eğitimcileri, bildiğiniz üzere bilim ve teknolojideki gelişmeler ve toplumsal ihtiyaçlardaki değişimler ile eğitim alanında öğrenmeye yönelik kuram, öğretime ilişkin yaklaşım, model ve yöntem ile ilgili yenilikler öğretim programlarında yenileme çalışmaları yapılmasını zorunlu kılmaktadır. Yenilenen programların istenen düzeyde uygulanabilmesi için öğretmenlerin çeşitli çalışmalarla yeterliklerinin geliştirilmesi gerekmektedir. Yeterlik alanları içerisinde ölçme ve değerlendirme önemli bir yer tutmaktadır. Öğretmenlerimiz programda belirtilen sürelerinin üçte birinden fazlasını ölçme ve değerlendirme ile ilgili etkinliklere harcamaktadırlar. Ölçme ve değerlendirmede etkili ve verimli olabilmek için öğretmenlerin önemli değerlendirme becerilerine ihtiyacı vardır. Bu konularda çeşitli dönemlerde yapılan çalışmalar, sınıf içi değerlendirme konusunda öğretmenlerin kendilerini yeterli hissetmediklerini göstermektedir. Bu kapsamda, öğretmenlerin yeterliklerinin arttırılması için Millî Eğitim Bakanlığı Ölçme, Değerlendirme ve Sınav Hizmetleri Genel Müdürlüğü ve UNICEF Türkiye Temsilciliği arasında imzalanan bir protokol ile “Okul ve Sınıf Tabanlı Değerlendirmeye Dayalı Öğretmen Kapasitesinin Güçlendirilmesi” çalışması hayata geçirilmiştir. Bu çalışmanın temel amacı, öğretmenlerin mesleki gelişiminin desteklenmesi için alan bazlı ve etkinlik temelli uygulamalarla öğretmenlerimizin özellikle biçimlendirici değerlendirme kapasitelerini arttırmak ve dezavantajlı öğrenciler de dâhil olmak üzere bütün öğrencilerimizin gelişimlerine daha bütüncül destek olabilmektir. Bu amaç kapsamında, biçimlendirici değerlendirme konusunda öğretmenlerimize kılavuzluk/rehberlik edecek bir öğretmen rehber kitapçığı ortaya konulmuştur. Öğretmen rehber kitapçığı toplam dört ana bölümden oluşmaktadır. Birinci bölümde ölçme ve değerlendirmenin temel kavramlarına atıfta bulunulmaktadır. İkinci bölümde biçimlendirici değerlendirme amacıyla kullanılabilecek teknik ve araçlara yer verilmiştir. Üçüncü bölümde öğretim programıyla ilişkilendirilip tasarlanan etkinlik örnekleri yer almaktadır. Son bölümde ise biçimlendirici değerlendirme sürecinde paydaşlar ile etkileşimde dikkat edilmesi gereken hususlar açıklanmaktadır. Çocuklarımıza ve öğretmenlerimize faydalı olması dileğiyle..
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