In, Ag, Al katkılı kurşunsuz Sn-Zn lehim alaşım sistemlerinin mekanik ve mikroyapısal özellikleri

Sn-Zn based lead free alloys are considered for replacing lead containing alloy systems for soldering. In this paper, In, Ag, Al doped Sn-Zn based systems were produced and investigated for mechanical and microstructural properties to obtain the most suitable system. Microstructures were observed by using an optic microscope. The samples' existing phases were investigated by using Energy Dispersive X-Ray analysis (EDX). Melting temperatures, the enthalpy of fusion and the specific heat change between the liquid and solid phases in the systems were determined with Differential Scanning Calorimetry (DSC). Also, microhardness values were measured at room temperature.Sn-Zn bazlı kurşunsuz alaşımlar, lehimleme için kurşun içeren alaşım sistemlerinin yerine kullanılmak üzere düşünülmektedir. Bu çalışmada, In, Ag, Al katkılı Sn-Zn esaslı sistemler üretilmiş ve en uygun sistemin elde edilmesi için mekanik ve mikro yapısal özellikler incelenmiştir. Mikro yapılar bir optik mikroskop kullanılarak gözlemlenmiştir. Numunelerin mevcut fazları Enerji Dağılım X-Işını Spektrometresi (EDX) kullanılarak araştırılmıştır. Sistemlerdeki erime sıcaklıkları, füzyon entalpisi ve sıvı ve katı fazlar arasındaki özgül ısı değişimi Diferansiyel Taramalı Kalorimetre (DSC) ile belirlenmiştir. Ayrıca oda sıcaklığında mikrosertlik değerleri de ölçülmüştür

On eqiform Darboux helices in Galilean 3-space

In this paper, we define equiform Darboux helices in a Galilean space (G_{3}) and obtain their explicit parameter equations. We show that equiform Darboux helices have only a non-isotropic axis and characterize equiform Darboux vectors of equiform Darboux helices in terms of equiform rectifying curves. We prove that an equiform Darboux vector of an equiform Darboux helix α is an equiform Darboux helix if an admissible curve (alpha) is a rectifying curve. We also prove that there are no equiform curves of constant precession and give some examples of equiform Darboux helices

Host-sensitized phosphorescence of Mn4+, Eu3+, and Yb3+ in MgAl2Si2O8

Mn4+ doped and Eu3+, Yb3+ co-doped MgAl2 Si2O8-based phosphors were prepared by conventional solid state reaction at 1,300 C. They were characterized by thermogravimetry, differential thermal analysis, X-ray powder diffraction, photoluminescence, and scanning electron microscopy. The luminescence mechanism of the phosphors, which showed broad red emission bands in the range of 600–715 nm and had a different maximum intensity when activated by UV illumination, was discussed. Such a red emission can be attributed to the intrinsic 2E + 4A2 transitions of Mn4+

Synthesis and photoluminescence analysis of Y1.50Sc0.50O3:Sm3+ and Y1.50Sc0.50O3:Dy3+ phosphors

In this study, Y1.50Sc0.50O3:Sm3+ and Y1.50Sc0.50O3:Dy3+ have been synthesized by a solid state reaction method and their photoluminescence (PL) properties have been investigated. Single-phase and well-crystallized cubic Y1.50Sc0.50O3:Sm3+ and Y1.50Sc0.50O3:Dy3+ phosphors are obtained after calcinations at 800 ºC and 900 ºC for 6 h. X-ray diffraction patterns confirm that both phosphors have a cubic phase without secondary phase. According to scanning electron microscope results, the particle size of both phosphors exhibit relatively irregular and their particle size are determinated to be between 0.27 µm–0.70 µm and 0.25 µm–2.04 µm for Y1.50Sc0.50O3:Sm3+ and Y1.50Sc0.50O3:Dy3+, respectively. The PL excitation and emission spectra are recorded for both types of the phosphors. Emission spectra of Y1.50Sc0.50O3:Sm3+ and Y1.50Sc0.50O3:Dy3+ are found to be typical for Sm3+and Dy3+

A Field of learning and living: suitability of school gardens for children

The aim of this study is to reveal the opinions of primary school teachers and school managers about the evaluation of primary school gardens for children. This study was conducted with phenomenological method is one of qualitative research designs. The data of study was collected through semi-structured interviews, study group consisted of 30 teachers and 12 school managers. Photographs of school gardens and students' drawings are other data collection tools of the research. The data were analyzed by content analysis method. The findings obtained that playgrounds are thought to be important in terms of supporting development of child, providing socialization, supporting learning and having fun. The majority of participants think that their school gardens are not enough. The lack of playgrounds in school gardens, the lack of green area and use of garden as a car park are examples of these inadequacies

Electroanalytical Characterization of Montelukast Sodium and Its Voltammetric Determination in Pharmaceutical Dosage Form and Biological Fluids

The electrochemical properties of montelukast sodium (MKST) at zinc oxide nanoparticles modified carbon paste electrode were investigated by cyclic voltammetry and square wave voltammetry. All studies were based on the irreversible and adsorption-controlled electrochemical reduction signal of montelukast sodium at about -0.7 vs. Ag/AgCl at pH 2.3 in methanol-Britton-Robinson buffer mixture. This adsorptive character of the molecule was used to develop a novel, validated, rapid, selective and simple square wave cathodic adsorptive stripping voltammeric method for the direct determination of montelukast sodium in pharmaceutical and biological fluids without time-consuming steps prior to drug assay. Peak current of electrochemical reduction of montelukast sodium was found to vary linearly with the concentration in the range from 1.0 x 10(-8) to 1.28 x 10(-6) mol L-1. In this method, limit of detection was found to be 7.7 x 10(-9) mol L-1. The method was applied to determine the content of MKST tablet and spiked human serum.Namik Kemal UniversityNamik Kemal University [NKU BAP.00.10.YL.14.03]This work was supported by the Research Fund of the Namik Kemal University. Project No. NKU BAP.00.10.YL.14.03. The authors would like to thank to Prof Esma Kilic for her valuable comments and suggestions on the manuscript

Ebeveyn Bakış Açısıyla Oyun: Çukurca İlçesi Örneği

Bu araştırmanın amacı, ebeveynlerin oyuna ilişkin bakış açılarının ortaya konulmasıdır. Araştırmanın çalışma grubunu Hakkâri–Çukurca ilçesinde ikamet eden toplamda 137 ebeveyn oluşturmaktadır. Nitel yöntemde yapılan bu araştırmada, veri toplama aracı olarak yarı yapılandırılmış görüşme formu kullanılmıştır. Araştırma sonucunda, ebeveynlerin oyunu eğlence olarak gördükleri ve çocuklar için de oyunun eğlence anlamına geldiğini düşündükleri, oyunun en çok çocuklar tarafından oynandığı, oyun araçları olarak çocukların oyuncakları tercih ettikleri, çocukların oyun ile eğlenerek öğrendikleri ve oyun paylaşımlarının en çok kardeşlerle yapıldığı sonucuna ulaşılmıştır. Ayrıca ebeveynlerin gün içerisinde çocuklarla geçirdikleri sürenin yarım saat ile iki saat arasında olduğu, çocuklarıyla günlük zamanı oyun aktiviteleriyle geçirdikleri ve oyun faaliyetlerini etkileyen en önemli faktörün teknolojik araç-gereçlerin olduğu sonucuna ulaşılmıştır.

Oxide ionic conductivity properties of binary δ-(Bi2O3)1 - x (Yb2O3) x system

In this study, after doping ytterbium oxide (Yb2O3) to a-bismuth trioxide (a-Bi2O3) in the range of 9% n 20% in a series of different mole ratios, heat treatment was performed by applying a cascade temperature rise in the range of 700–790 C for 48 hours and new phases were obtained in the (Bi2O3)1 x(Yb2O3)x system. After 24 hours of heat treatment at 700 C and 750 C and 48 hours of heat treatment at 790 C, mixtures containing 9–20 mol% Yb2O3 formed a face-centered cubic phase. With the help of X-ray diffraction (XRD), the crystal systems and lattice parameters of the solid solutions were obtained and their characterization was carried out. The surfaces of the solid solutions were detected by a scanning electron microscope (SEM). Thermal measurements were made by using a simultaneous DTA/TGA (differential thermal analysis/thermogravimetric analysis) system. The total conductivity (sT) in the d-Bi2O3 doped with Yb2O3 system was measured using the four-probe DC method

Photoluminescence properties of Eu3+-activated Y1.50Sc0.50O3 phosphors

In this research, Eu3+ activated and Dy3+-co-doped Y2O3 based phosphors have been synthesized by solid-state reaction method under open atmosphere. The host lattice is composed of 0.25 moles of Sc2O3 which is added to phosphor composition. Thus, Sc3+ substitution of Y3+ ions is implemented to form Y1.40Sc0.50O3 host lattice. The thermal analysis (DTA/TG) have been carried out from 50 °C to 1400 °C for preliminary examination of thermal behavior of phosphors during heat treatments. After the heating process, the phase formations are characterized by X-ray diffraction resulted as Y2O3 single phase cubic structure. The effects of Eu3+ and Dy3+ dopant ions on the photoluminescence and phase formation properties of the hosts are investigated and determined as Dy3+-co-doped phoshor has the reduced excitation/emission intensities as well as decay lifetimes

Sismik İzolatörlü Yapıların Tasarımına Etki Eden Faktörlerin İncelenmesi

Bu çalışmada, yalıtım sisteminin tasarımı, Türkiye Bina Deprem Yönetmeliği 2018’de (TBDY-2018) tanımlanan Etkin Deprem Yükü Yöntemi kullanılarak gerçekleştirilmiştir. TBDY-2018 kriterleri dikkate alınarak, 4 katlı betonarme bir yapı altında kurşun çekirdekli kauçuk izolatörün tasarımı yapılmış olup farklı zemin sınıfları için karakteristik dayanım oranı (Q/W) ile izolasyon periyodu (T) değişiminin sismik izolatör davranışa etkisinin belirlenmesi amaçlanmıştır. Ayrıca, fay hattından uzaklığın etkisi incelenmiş, bu amaçla Sakarya ilinde biri fay hattına yakın (Arifiye), diğeri fay hattından uzak (Karasu) olmak üzere iki lokasyon seçilmiştir. Sismik izolasyon seviyesinde oluşan yerdeğiştirme, kesme kuvveti ve ivme-yerdeğiştirme tepki spektrumları belirlenmiştir. Tasarımcıların izolasyon sisteminin tasarım parametrelerini hızlı bir şekilde belirlemelerini sağlamak amacıyla taban kesme oranı-deplasman grafikleri elde edilmiştir. Araştırmada, fay hattından uzaklığın, zemin sınıfının, izolasyon periyot değerinin ve karakteristik dayanımının, maksimum izolatör deplasmanı ve maksimum izolatör kuvveti değerlerini önemli ölçüde etkilediği sonucuna varılmıştır