Search

Bu araştırmada, Medya Okuryazarlığı dersine ilişkin öğrenci tutumlarını belirlemek, öğretmen ile öğretmen adaylarının görüşlerinin tespit etmek amaçlanmıştır. Araştırmada, nicel ve nitel araştırma yöntemleri bir arada kullanıldığından çalışma karma yöntemle desenlenmiştir. Araştırmanın nicel boyutunda tutum ölçeği, nitel boyutunda ise görüşme formu kullanılmıştır. Araştırmanın nicel verilerinin toplandığı çalışma grubunu, 2017-2018 eğitim-öğretim yılında Giresun ilinde seçmeli Medya Okuryazarlığı dersinin verildiği 5 ortaokulda Medya Okuryazarlığı dersi alan 153 sekizinci sınıf öğrencisi ile Medya Okuryazarlığı dersini almayan 103 yedinci sınıf öğrencisi oluşturmaktadır. Toplamda 256 öğrenci araştırmaya katılmıştır. Nitel verilerinin toplandığı çalışma grubunu ise seçmeli Medya Okuryazarlığı dersinin verildiği okullarda görev yapan 5 sosyal bilgiler, 1 Türkçe öğretmeni ve Giresun Üniversitesi Eğitim Fakültesinde öğrenim gören 15 Türkçe ile 15 sosyal bilgiler öğretmen adayı oluşturmaktadır. Nicel verilerin analizinde SPSS programı kullanılmıştır. Nitel verilerin analizinde ise görüşmeler yoluyla toplanan veriler içerik analizi ile çözümlenmiştir. Çalışmanın bulgularından hareketle; Medya Okuryazarlığı dersini alan ve almayan öğrencilerin medyanın algılanma biçimi boyutuna yönelik tutumları arasında anlamlı bir fark olmadığı, öğrencilerin medya araçlarını tercih sıraları aynı olup sırasıyla internet, televizyon, dergi, gazete, radyoyu tercih ettikleri, internet tercihinde dersi alanların, dergi tercihinde ise dersi almayanların lehine anlamsal fark olduğu, Medya Okuryazarlığı dersinin gereksiz bir ders olarak algılandığı, derste Medya Okuryazarlığına ilişkin konuların işlenmediği, bu ders için ayrılan sürenin başka branş derslerinin tamamlayıcısı olarak kullanıldığı sonuçlarına ulaşılmıştır.

Red blood cell (RBC) deformability has vital importance for microcirculation in the body, as RBCs travel in narrow capillaries under shear stress. Deformability can be defined as a remarkable cell ability to change shape in response to an external force which allows the cell to pass through the narrowest blood capillaries. Previous studies showed that RBC deformability could be regulated by Ca2+/protein kinase C (PKC) signaling mechanisms due to the phosphorylative changes in RBC membrane proteins by kinases and phosphatases. We investigated the roles of Ca2+/PKC signaling pathway on RBC mechanical responses and impaired RBC deformability under continuous shear stress (SS). A protein kinase C inhibitor Chelerythrine, a tyrosine phosphatase inhibitor Calpeptin, and a calcium channel blocker Verapamil were applied into human blood samples in 1 micromolar concentration. Samples with drugs were treated with or without 3 mM Ca2+. A shear stress at 5 Pa level was applied to each sample continuously for 300 s. RBC deformability was measured by a laser-assisted optical rotational cell analyzer (LORRCA) and was calculated as the change in elongation index (EI) of RBC upon a range of shear stress (SS, 0.3-50 Pa). RBC mechanical stress responses were evaluated before and after continuous SS through the parameterization of EI-SS curves. The drug administrations did not produce any significant alterations in RBC mechanical responses when they were applied alone. However, the application of the drugs together with Ca2+ substantially increased RBC deformability compared to calcium alone. Verapamil significantly improved Ca2+-induced impairments of deformability both before and after 5 Pa SS exposure (p < 0.0001). Calpeptin and Chelerythrine significantly ameliorated impaired deformability only after continuous SS (p < 0.05). Shear-induced improvements of deformability were conserved by the drug administrations although shear-induced deformability was impaired when the drugs were applied with calcium. The blocking of Ca2+ channel by Verapamil improved impaired RBC mechanical responses independent of the SS effect. The inhibition of tyrosine phosphatase and protein kinase C by Calpeptin and Chelerythrine, respectively, exhibited ameliorating effects on calcium-impaired deformability with the contribution of shear stress. The modulation of Ca2+/ PKC signaling pathway could regulate the mechanical stress responses of RBCs when cells are under continuous SS exposure. Shear-induced improvements in the mechanical properties of RBCs by this signaling mechanism could facilitate RBC flow in the microcirculation of pathophysiological disorders, wherein Ca2+ homeostasis is disturbed and RBC deformability is reduced.

Among Fe-Ni-Co alloys, Kovar (53% Fe-29% Ni-17% Co) designated as ASTM F-15[1], is a well-known glass-sealing alloy. It also is classified as low–expansion alloy [2]. Low expansion is required to avoid internal stresses for applications that involve strong ceramic to metal joining. One of the most significant problems in vacuum systems is the outgassing which is the liberation of a gas that was dissolved, trapped, frozen or absorbed in a material. To decrease the outgassing rate from the chamber walls, the material should have smooth and passivated surface finish [3]. Electropolishing, one of the finishing methods applied to decrease surface roughness, is appropriate for the systems involving parts of simple and complex geometries. However, there is very limited information on the electropolishing of Kovar alloy in the literature. Acetic acid (glacial)–perchloric acid (60%) mixture, stated as a cleaning solution before soldering Kovar [4], was used as electropolishing electrolyte in this work. A systematic study was conducted in 5 to 15% perchloric acid containing electrolytes at 25 to 35°C to find the optimum polishing conditions. A two–electrode setup employing Kovar anode and stainless steel cathode was used to perform voltammetric studies to determine low and high levels of current densities. According to linear sweep voltammetry results, shown in Figure 1, 200 to 600 mA/cm2current density range was selected to optimize electropolishing. Experimental route was designed using three parameters (current density, concentration and temperature) and three levels. The duration was kept constant as 5 minutes. Effect of electropolishing duration was determined by utilizing the condition that revealed the lowest roughness in 5 minutes. It was found that, the surface roughness of Kovar samples (having dimensions of 10×25×2 mm), was decreased from 0.21µm to 0.06 µmRa in a 15% perchloric acid containing solution. ADDIN EN.REFLIST 1. ASTMInternational, Standard Specification for Iron-Nickel-Cobalt Sealing Alloy. 2009. 2. Special-Purpose Nickel Alloys, in ASM Specialty Handbook: Nickel, Cobalt, and Their Alloys. 2000, ASM International. p. 92-101. 3. Tajiri, K., Pit-free electropolishing of aluminum and its application for process chamber. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 1998. 16(3): p. 1196. 4. Vianco, P.T., F.M. Hosking, and J.A. Rejent, Solderability Testing of Kovar with 60Sn-40Pb Solder and Organic Fluxes, in 19th International AWS Brazing and Soldering Conference. 1988: New Orleans, LA. Figure 1