Investigation of the strees and thermal effects on the martensitic transformations in the Fe-%12,5Mn-%5,5Si-%9Cr-%3,5Ni Alloy

YÖK Tez ID: 154903Bu çalışmada, şekil hatırlamalı Fe-%1 2,5Mn-%5,5Si-%9Cr-%3,5Ni alaşımında meydana gelen martensitik dönüşümlerin morfolojik, kristalografik, mekanik ve termodinamik özellikleri üzerine termal ve dış zorun etkileri incelendi. Ayrıca termal ve dış zorun etkileri ile austenite yapı içinde meydana gelen dislokasyonların ve yığılma kusurlarının martensite yapı ile etkileşimleri ele alındı. Austenite yapı içinde termal etki ile yalnızca e (h.c.p.) martensite'nin meydana geldiği, dış zorun etkisi ile ise hem e martensite hem de a' (b.c.c.) martensite yapıların meydana geldiği yüzey ve mikro yapı incelemelerinde ortaya çıktı. Austenite kristal içinde oluşan e martensite'nin alışım (habit) düzleminin {111}y düzlemine paralel olduğu ve e martensite fazile austenite faz arasında Shoji-Nishiyama türü kristalografik dönme bağıntısının bulunduğu sonucuna varıldı. Dış zorun etkisi ile s martensite plakalarının kesişme bölgelerinde oluşan a' martensite yapının kristalografik incelemelerinde austenite ve martensite fazların düzlem ve doğrultuları arasında {1 1 1}r // {0001}E // {T01}«-, y // B // ". şeklinde bir ilişki olduğu bulundu ve bunun Kurdjumov-Sachs türü dönme bağıntısına uyduğu görüldü. Bu alaşımda ısıl işlem süresinin artması ile tane (grain) boyutunun büyüdüğü ve martensite miktarının arttığı gözlendi. Yüzey incelemelerinde plastik deformasyon etkisi ile s martensite plakalarının şekillerinin ve yönelimlerinin değiştiği görüldü. Mikro yapı gözlemlerinde plastik deformasyon sonucu yığılma kusurlarının arttığı, martensite plakalarının kalınlaştığı ve bu plakaların kesişme bölgelerinde a' martensite'nin oluştuğu görüldü. Fe-%12,5Mn-%5,5Si-%9Cr-%3I5Ni alaşımında austenite fazda bulunan kristal taneciklerinin büyüklüğünün ve oluşan martensite fazın miktarının alaşımın mekanik özelliklerini nasıl değiştirdiği zor-zorlanma deneyleri ile araştırıldı. Homojenleştirme süresinin ve plastik zorlanmanın artması ile austenite-martensite dönüşüm sıcaklığının arttığı görüldü. Anahtar Kelimeler: Austenite, ? Martensite, á Martensite, Martensitik Faz Dönüşümü, Plastik Deformasyon, Zor-Zorlanma Eğrisi, Austenite- Martensite Dönüşüm Sıcaklığı, Dislokasyon, Yığılma Kusurları, Tane Sınırı.In this study, thermal and external stress effects on the martensitic transformations which occured in Fe-%12,5Mn-%5,5Si-%9Cr-%3,5Ni shape memory alloy were investigated from morphologic, crystallographic, mechanic and thermodynamic view points. We also studied the interactions of dislocations and stacking faults, which form in the austenite matrix through thermal and external stress, with martensite matrix. We observed that in the austenite structure e (h.c.p.) martensite occured only with thermal effects and outer external stress both e and a' (b.cc.) martensite structures formed with surface and microstructure analysis. The habit plane of e martensite was found to be parallel to {111}r planes of austenite crystal and its mcrystallographic determinations revealed the existence of Shoji-Nishiyama type orientation relationship between the austenite and s martensite phases. The electron diffraction analysis indicated that the orientation relationship of the a' martensite, which formed due to external stress at the intersection of the e martensite plate's, as {1 1 1}? // {0001}8 // {T01}"-, r // 8 // a', and it was observed that this was in accord to the Kurdjumov-Sachs type orientation relationship. It is observed that by increasing homogenization time, the austenite grain size and the amount of martensite were increased at this alloy. Changes of shape and orientation of s martensite plates with the effect of plastic deformation were revealed with surface analysis. Also as a result of the compression test, increasing of stacking faults density, thickening of martensite plates and a' martensites which form at the intersections of this plates were observed with microstructure analysis. It is investigated that how the size of grains and amount of martensite phase change the mechanical properties of the Fe~%12,5Mn-%5,5Si- %9Cr-%3,5Ni alloy in the austenite phase by stress-strain tests. By the increase of homogenization time and plastic deformation, it was observed that the austenite-martensite phase transformation temperature also increased. Key Words: Austenite, ? Martensite, a' Martensite, Martensitic Phase Transformations, Plastic Deformation, Stress-Strain Curve, Austenite- Martensite Transformation Temperature, Dislocation, Stacking Faults, Grain Boundary

Fe-% 12,5mn- % 5,5si- % 9cr- %3,5ni Alaşımında Martensitik Dönüşümler Üzerine Termal Ve Zor Etkilerinin İncelenmesi

Tez (Doktora) -- Kırıkkale Üniversitesi48262

Fe-Mn-Mo-Si alaşımlarında termal etkili faz dönüşümlerinin mikro yapı incelemeleri

In this study, structural and crystallographic properties of phasetransformations in Fe–Mn– Mo–Si (Mn = 15.14 wt.% and 18.45 wt.%) alloys wereinvestigated. The effects of heat treatment temperature on microstructure wereinvestigated by Scanning Electron Microscopy (SEM) and Metallurgical Microscopy(MM). In addition to this, crystallographic properties of phase transformationswere revealed by using Transmission Electron Microscopy (TEM) and X–RayDiffraction (XRD) methods. In the samples subjected to heat treatment at 750 C, itwas observed that bainite structure was formed in the alloy where Mn amount waslow and ferrite structure in the alloy where Mn amount was higher. In addition, itwas found that both alloys heat–treated at 900 C had the same microstructure(pearlite structure) in SEM and MM microscopy. At the same time, microstructureobservations revealed that bainite and pearlite structures contain a mixture offerrite and cementite. In the TEM studies it was revealed by electron diffractionpattern analyses that bainite and ferrite phase crystallized in b.c.c. structure andcementite phase in orthorhombic structure. → type transformation wasobserved for –bainite formation, and orientation relationship was found as(1̅11)//(011) , [101]//[1̅11̅].Bu çalışmada, Fe-%XMn-Mo-Si (X=15,14 ve 18,45) alaşımlarında termal etki ile meydana gelen faz dönüşümlerinin yapısal ve kristalografik özellikleri incelenmiştir. Isıl işlem sıcaklığının mikro yapısı üzerine etkileri Taramalı Elektron Mikroskobu (SEM) ve Metalürji Mikroskobu (MM) incelemeleri ile yapıldı. Bunun yanı sıra kristalografik özellikleri ise Geçirmeli Elektron Mikroskobu (TEM) ve XIşınları Kırınımı (XRD) yöntemleri kullanılarak ortaya çıkarılmıştır. 750 C’ de ısıl işleme tabi tutulan numunelerde Mn miktarının az olduğu alaşımda beynit yapı oluşurken Mn miktarının daha fazla olduğu alaşımda ferrit yapının oluştuğu gözlendi. Ek olarak, 900 C'de ısıl işlem görmüş her iki alaşımın da SEM ve MM mikroskopisinde aynı mikro yapıya (perlit yapı) sahip olduğu bulundu. Aynı zamanda, beynit ve perlit yapılarının ferrit ve sementit karışımını içerdiği mikro yapı gözlemleri ile ortaya konuldu. TEM incelemelerinde elektron kırınım deseni analizleri sayesinde beynit ve ferrit fazın b.c.c. yapısında, sementit fazın ise ortorombik yapıda kristalleştiği ortaya konuldu. -beynit oluşumu için türü dönüşüm gözlendi ve dönme bağımlılığı (1̅11)//(011) , [101]//[1̅11̅] olarak bulundu

Investigation of Technological Pedagogical Field Knowledge of Science Teachers

Bu çalışmanın amacı, fen bilimleri öğretmenlerinin alan bilgilerinin teknoloji ile entegrasyonu sonucunda özyeterlik inançlarını incelemektir. Yapılan çalışmada hem nitel hem de nicel araştırma yöntemlerinden yararlanılmıştır. Araştırma basit seçkisiz örnekleme yöntemi kapsamında Kırşehir ilinde görev yapmakta olan 75 fen bilimleri öğretmeni ile gerçekleştirilmiştir. Araştırmanın nicel kısmında TPAB öz-yeterlik ölçeği, nitel kısmında ise yarı yapılandırılmış görüşme formu kullanılmıştır. Nicel verilerin analizinde SPSS programı, nitel verilerin analizinde ise betimsel ve içerik analizi birlikte kullanılmıştır. Araştırma sonucunda, teknolojik yeniliklerin derse entegre edilmesi ile öğretmenlerin öz yeterlik inançlarının geliştiği gözlenmiştir. Bununla birlikte öğretim teknolojilerinin cinsiyete bağlı olarak değişmediği, fakat TPAB öz yeterlik inançlarının cinsiyete göre erkekler lehine değiştiği sonucuna ulaşılmıştır. Mezun olunan okul türünün öğretim teknolojileri algılarını etkilediği görülmüştür. Fen bilimleri öğretmenlerinin TPAB konusunda bilgi eksikliklerinin (Örn. teknoloji ile pedagojik alan bilginin entegrasyonunda) olduğu belirlenmiştir. Bu eksikliklerin hizmet içi eğitimler ile giderilebileceği düşünülmektedir. Aynı zamanda birçok öğretmenimizin günümüz teknolojisine uyum sağlamada (internet erişimi, alt yapı ve donanım eksikliği, güncelleme eksiklikleri vb.) zorlandıkları tespit edilmiştirThe aim of this study is to investigate the self-efficacy beliefs of science teachers as a result of integration of field knowledge with technology. Both qualitative and quantitative research methods were utilized in the study. The research was carried out with 75 science teachers working in Kırşehir within the scope of simple random sampling method. Technological Pedagogical Field Knowledge (TPFK) self-efficacy scale was used in the quantitative part of the study, while semi-structured interview form was used in the qualitative part. SPSS program was used in the analysis of quantitative data, while descriptive and content analyses were both used in the analysis of qualitative data. As a result of the research, it was observed that teachers' self-efficacy beliefs are developed by integrating technological innovations into the course. At the same time, it was concluded that instructional technologies do not change depending on gender, but TPFK self-efficacy beliefs change in favour of men. It was observed that the type of school graduated affects the perception of instructional technologies. It was determined that science teachers lack knowledge about TPFK (e.g. in the integration of technology and pedagogical field knowledge). It is thought that these deficiencies can be solved by in-service trainings. At the same time, it was found that many teachers had difficulty in adapting to today's technology (internet access, lack of infrastructure and hardware, lack of updates, etc.)

Effect of mn amount on phase transformations and magnetic properties in fe-mn-mo-si alloys

WOS:000607668200002In this study, microstructural and crystallographic properties of phase transformations occurring with thermal effect in Fe- XMn-Mo-Si (X = 15.14wt.% ve 18.45wt.%) alloys have been investigated. The effects of (wt.%) Mn rates in the alloy on the characteristics of phase transformations were investigated by using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD). SEM and TEM investigations was observed that two different martensite (ϵ and α' ) structures were formed in austenite grain. In addition, in TEM observations, the interface regions were selected over the bright field image. Crystallographic orientation relationships were obtained by the analyses of electron diffraction patterns from the interface regions. γ → α' type transformation was observed for α' particle formation, and orientation relationship was found as (1-11)γ // (011)α' , [101]γ // [1-11-]α' and, γ → ϵ type transformation was observed for ϵ martensite plate formation, and the orientation relationship was found as (1-11-)γ // (0002-)ϵ, [1- 1-0]γ // [2-110]ϵ. It was noticed that this orientation relationships were compatible with the literature (Kurdjumov-Sachs and Shoji-Nishiyama orientation relationship). Precipitation phase (carbide) formation was observed in microstructure analyses. The changes in the magnetic properties of the alloys having different rates of Mn as a consequence of thermal effect phase transformations was investigated by using Mossbauer Spectroscopy. The internal magnetic field, volume fractions (transformation rates), isomer shift values and magnetic characteristics of the main and product phases were revealed by Mossbauer Spectroscopy. In the Mossbauer Spectrum, it was noticed that ϵ-martensite and γ-austenite structures showed paramagnetic single-peak, and α' -martensite showed ferromagnetic six-peaks

FEN OKURYAZARLIĞI ÜZERİNE EPİSTEMOLOJİK İNANÇLAR VE ÖZYETERLİK ETKİSİNİ İNCELEYEN BİR MODEL

Araştırmada fen bilgisi öğretmen adaylarının fen okuryazarlıklarının, epistemolojik inançları ve fen bilgisi öğretimi öz yeterlik inançlarıyla ne düzeyde açıklandığını bir model aracılığıyla incelemek amaçlanmıştır. Araştırmanın bağımlı değişkeni üzerindeki bağımsız değişkenlerin doğrudan ve dolaylı etkilerini belirleyecek bir model oluşturulmuş ve test edilmiştir. Araştırmada nedensel karşılaştırmalı desen kullanılmıştır, araştırmanın çalışma grubunu farklı üniversitelerden 415 bayan ve 181 erkek olmak üzere 596 üniversite öğrencisi oluşturmaktadır. Araştırmada veri toplama aracı olarak Laugksch ve Spargo (1996), tarafından geliştirilen ve Yetişir (2007), tarafından Türkçe'ye uyarlanan temel fen ve teknoloji okuryazarlık ölçeği, Riggs ve Enochs (1990), tarafından geliştirilen ve Özkan, Tekkayave Çakıroğlu (2002) tarafından Türkçe'ye uyarlanan fen bilgisi öğretimi öz yeterlik inancı ölçeği ve Schommer (1990), tarafından geliştirilen ve Deryakulu ve Büyüköztürk (2002) tarafından Türkçe'ye uyarlanan Epistemolojik inanç ölçeği kullanılmıştır. Araştırmadan elde edilen veriler SPSS 21 ve AMOS programlarıyla analiz edilmiştir. Araştırmada model testi için path analizi yapılmıştır. Araştırma sonucunda fen bilgisi öğretmen adaylarının fen okuryazarlıklarının, epistemolojik inançları bakımından doğrudan, fen öğretimi öz yeterlik inançları bakımından ise dolaylı olarak açıklandığı belirlenmiştir. Çalışmada değişkenler (fen bilgisi öğretmen adaylarının fen okur yazarlığı, epistemolojik inançları ve fen öğretimi alanındaki öz yeterlik inançları) arasındaki ilişki için kavramsal bir model önerilmiştir. Tek bir doğru olduğuna dair inanç değişkeninin bağımsız ve diğer değişkenlerle etkileşimsiz olduğu görülmüş ve bu değişken modele alınmamıştırThe aim of the research is to investigate to what extent the science literacy of science teacher candidates is explained by their epistemological beliefs and self-efficacy beliefs of science teaching through a model. A model was created and tested to determine the direct and indirect effects of the independent variables on the dependent variables of the research. The causal-comparative design was used in the research, and the study group of the research is composed of 596 university students, 415 of which are female and 181 of which are male. The basic science and technology literacy scale developed by Laugksch and Spargo (1996) and adapted into Turkish language by Yetişir (2007); the science teaching self-efficacy belief scale developed by Riggs and Enochs (1990) and adapted into Turkish language by Özkan, Tekkaya and Çakıroğlu (2002); and the Epistemological beliefs inventory developed by Schommer (1990) and adapted into Turkish language by Deryakulu and Büyüköztürk (2002) were used in the research as data collecting tools. The data obtained from the research were analyzed with SPSS 21 and AMOS software packages. The path analysis was performed for testing the model in the research.It was consequently determined in the research that scientific literacy of science teacher candidates was explained by their epistemological beliefs directly, their science teaching self-efficacy beliefs indirectly. In the study, a conceptual model was suggested for the relationship between the variables (science literacy of science teacher candidates, their epistemological beliefs and their selfefficacy beliefs in science teaching). It was observed that the variable of the belief that there is only one correct was correlation inefficient with independent and the other variables, and this variable wasn’t taken into the model.The main aim of science teaching is to grow scientific literate individuals. Growing individuals who can decide when faced with a problem on science, who can make suggestions on scientific discussions, know the basic concepts on science and can use these concepts for the problems in their lives, is rather important for developing societies (Çepni, Bacanak and Küçük, 2003). Although scientists make a lot of definitions about science literacy, a common definition can’t be developed. Yet, in general terms, a common and basic concept can be mentioned for the aims in science teaching in the schools (Deboer, 2000; Robert, 1983; as cited in Laugksch, 2000). The other variable beside science literacy that effects the scientific development of individuals is epistemological beliefs. These beliefs are about the nature of knowledge and learning but not a strict philosophical perception (Schommer, 1998). An extended definition of epistemological belief is the subjective beliefs about what knowledge is and how knowing and learning ocur. There is a consistent relation between epistemological beliefs and learning and studying strategies of the students. The students who have improved beliefs in learning process use more qualified learning strategies and can be more successful in terms of academic than the students who have unimproved epistemological beliefs (Deryakulu, 2004). The characteristics that science teachers must have are science literacy and developed epistemological and self-efficacy beliefs. Selfefficacy is one of the concepts that came to forefront in Bandura’s social learning theory. Bandura firstly mentioned about this concept in his work "Self-efficacy: Toward a Unifying Theory of Behavioral Change" in 1977 (Bıkmaz, 2004; Pajares, 2002). Self-efficacy is an important qualification for forming behaviours and individual’s judgement about himself for making necessary organisations and sustaining successfully (Bandura, 1997). The self-efficacy in science education can be defined as the judgment about the students’ own skills for participation, motivation and as a result the success of them and effective and fertile science teaching of teachers (Küçükyılmaz and Duban, 2006). So, the low or high selfefficacy of the teachers may affect the applications of the teachers in science education (Schriver and Czerniak, 1999). In the study, the self-efficacy belief in science education is very important in terms of science teacher candidates. The teacher candidates with high self-efficacy beliefs will be more determined, knowing what he wants and what he must do. In this study, the science literacy of the teacher candidates were explained in terms of the variables, epistemological belief and self-efficacy belief for science teaching, and the reasons and results were discussed comparatively CONCEPTUAL FRAMEWORK It can be said that, as well as teachers’ personal characteristics, their educational process at faculty of education has a great role for their scientific literacy. That is why many research has been done about the level of scientific literacy on science teacher candidates. It can be thought that scientific literacy of science teacher candidates is influenced by epistemological beliefs and self-efficacy beliefs. Yet, there is no research in literature. Searching how science candidate teacher’s scientific literacy is predicted by their epistemological beliefs and self efficacy beliefs on science teaching has a crucial role on teacher’s education, correcting deficiencies in science teaching field and enlighting for further studies. METHOD In this study, casual-comparative research method, one of the scanning models, was used. Casual-comparative researches are for determining the reasons of a natural situation or event and the variables affecting these reasons or the results of an effect This method was used for explaining the science literacy of teacher candidates depending on the epistemological belief and the variables of self-efficacy belief for science teaching. Data Collection Tools The Scale of Basic Science and Technology Literacy: This scale used in the study was developed by Laugksch and Spargo (1996) and adapted to Turkish by Yetişir (2007). The Scale of Self-Efficacy Belief on Science Teaching: This scale was developed by Riggs and Enochs (1990) and adopted to Turkish by Özkan, Tekkaya and Çakıroğlu (2002). The Scale of Epistemological Belief: This scale was developed by Schommer (1990) and adopted to Turkish by Deryakulu and Büyüköztürk (2002). FINDINGS In the study, a conceptual model was suggested for the relationship between the variables (science literacy of science teacher candidates, their epistemological beliefs and their self-efficacy beliefs in science teaching). It was observed that the variable of the belief that there is only one correct was correlation inefficient with independent and the other variables, and this variable wasn’t taken into the model. The coefficient of concordance for ultimate model was quite above the accepted limit. As CFI, IFI, NFI, TLI and RFI values are over .90 and RMSA is under .05, the model can be evaluated as good fitted (Şimşek, 2007). The fit indices are high in the study, so it can be said that the model has high fit.Discussion for Direct Effects In generally, it can be stated that the epistemological beliefs of science teacher candidates influences the science literacy directly As a result of the study, it was found that the belief that learning depends on effort, the sub-dimension of epistemological belief, influenced the nature of science, the sub-dimension of science literacy, directly. Accordingly, it can be said that the more the level of the belief that learning depends on effort in terms of science teacher candidates increases, the more the level of science literacy for the nature of science increases. The other dimension that explains the nature of science is the belief that learning depends on skill. It was observed that the more the belief that learning depends on skill increased, the more science literacy level for the nature of science increased. But this effect is lower than the dimension of the belief that learning depends on effort. The nature of science includes the concepts of reason and imagination, too. When it is thought that the people who have learning skills can use their reason and imagination more effectively, the relationship between the belief level that learning depends on skill and the perception of the nature of science can be explained. The other independent variable of the study is the impact of science and technology on society, the sub-dimension of science literacy. The first variable influencing it directly is the belief that learning depends on effort. The more the belief that learning depends on effort increases, the more the perception level for the impact of science and technology on society increases The other variable that influences the impact of science and technology on society, the sub-dimension of science literacy, directly is the belief that learning depends on skill. But the relationship between them isn’t a powerful relation. The reason may be higher beliefs of individuals that learning depends on effort than the belief depends on skill. The last of independent variable in the model is the science content knowledge, the sub-dimension of science literacy. The first variable that influences the science content knowledge is the belief that learning depends on effort. It is understood that the more the belief that learning depends on effort increases, the more science content knowledge increases. This relation is one of the highest relations in the model. The reason may be that the students with developed beliefs that learning depends on effort are generally the students who study systematically and are successful, and the science content knowledge of these students is developed The other variable that influences the science content knowledge is the belief that learning depends on skill, but like the other independent variable, its degree of influence is lower than the belief that learning depends on effort. Still, there is a relationship between the belief that learning depends on skill and the science content knowledge. The reason of this may be that the individuals link their success to learning effects or intelligence. Discussion for Indirect Effects At the end of the research, it was observed that the self-efficacy beliefs of science teacher candidates influenced the science literacy indirectly from epistemological beliefs. When the search model was examined, it was noticed that the personal self-efficacy belief in science teaching influenced the nature of science from the belief that learning depends on effort. It is understood from the model that the personal self-efficacy belief in science teaching influences the impact of science and technology on society through the belief that learning depends on effort. Science can be said to be related to environment, daily life and nature, so the individuals with high personal self-efficacy belief are expected to have high perception on the impact of science and technology on society. Also, it is noticed from the model that the personal self-efficacy belief in science teaching influences the science content knowledge from the belief that learning depends on effort Personal self-efficacy belief influences the nature of science from the belief that learning depends on skill. From the model, it can be understood that personal self-efficacy belief on science teaching influences the impact of science and technology on society through the belief that learning depends on skill. But this effect is weaker than the effect of belief that learning depends on effort. The reason of this may be that the teacher candidates’ having higher beliefs that learning depends on effort It is occurred that personal self-efficacy belief in science teaching influences the science content knowledge through the belief that learning depends on skill. This effect is weaker than the effect that occurs through the belief that learning depends on effort because it may be that individuals think that effort is more effective than skill in term of reaching the knowledge. The other variable in the model is the outcome expectation in science teaching. It is the weakest effective variable for science literacy. The outcome expectation in science teaching influences the impact of science and technology on society through the beliefs that learning depends on effort and skill. Although this effect is higher than affecting the nature of science, it is still weak. Also, the outcome expectation in science teaching influences the science content knowledge through the beliefs that learning depends on effort and skill, and it is again a weak effect. This may be because the effects of science content knowledge and science and technology on society are better perceived by the teacher candidates than the nature of science In the study carried out for the science teacher candidates, the following conclusions some of which are compatible to the literature and some are different were arrived: The Results for Direct Effects As a result of the study, the belief that learning depends on the effort is identified as the variable that directly influences the nature of science. According to this result, the more the teacher candidates have increasing level of beliefs that learning depends on the effort, the higher their perceptions related to the nature of science are. Besides, the other variable that influences the nature of science is the belief that learning depends on skill. Accordingly, the more the teacher candidates have increasing level of beliefs that learning depends on the skill, the higher their perceptions related to the nature of science are. But its effectiveness is weaker than the belief that learning depends on effort. The other independent variable is the impact of science and technology on society, and the belief that learning depends on effort influences this variable directly. Accordingly, the more the belief that learning depends on effort increases, the more perception levels of the teacher candidates on the impact of science and technology on society increases. Another variable that influences the impact of science and technology on society directly is the belief that learning depend on skill. Accordingly, the more the belief that learning depends on skill increases, the more the perception levels of individuals on the impact of science and technology on society increases, but this effect is weaker than the effect of belief that learning depends on effort. The other independent variable of the study is the science content knowledge. The belief that learning depend on effort influences this variable directly, so the more the belief that learning depends on effort increases, the more the science content knowledge of the teacher candidates increases. This direct effect is the most powerful effect, too. The other variable that influences the science content knowledge directly is the belief that learning depends on skill. Accordingly, the more the belief that learning depends on skill increases, the more the science content knowledge of the teacher candidates increases. The Results for Indirect Effects As a result of the study, personal self-efficacy belief in science teaching influences indirectly the nature of science, the impact of science and technology on society and the science content knowledge through the belief that learning depends on effort. In other words, personal selfefficacy belief in science teaching influences the belief that learning depends on effort directly, and the belief that learning depends on effort influences the nature of science, the impact of science and technology on society and science content knowledge directly. As a result of the study, personal self-efficacy belief in science teaching influences indirectly the nature of science, the impact of science and technology on society and the science content knowledge through the belief that learning depends on skill. In other words, personal self-efficacy belief in science teaching influences the belief that learning depends on skill directly, and the belief that learning depends on skill influences the nature of science, the impact of science and technology on society and science content knowledge directly. But this effect is weaker than the mediator variable, the belief that learning depends on effort. In the study the other indirect effect is the outcome expectation. It influences the nature of science, the impact of science and technology on society and science content knowledge indirectly through the belief that learning depends on effort and the belief that learning depends on skill. This effect is the weakest in the model. This is because there is a weak relationship between the belief that learning depends on skill and the outcome expectation in science teaching. In the study, a model was formed, which tries to explain the science literacy through epistemological beliefs and self-efficacy beliefs in science teaching. It is concluded that science literacy can be explained by epistemological beliefs and self-efficacy beliefs. The study is limited to the study group. The repeat of the study in other universities can contribute to the generalization of results. Also, epistemological beliefs and selfefficacy belief was used as the descriptors of science literacy in the study. This may be the constraint of the study. In this context, to do the study again by adding variables like motivation and self-regulation may be helpful for healthier knowledge on this subject. Casual-comparative research model, one of scanning models, was used in this study, but it may contribute to use different experimental and qualitative studies for the generalization of the results. Also, the study was conducted only for the science teacher candidates. If the same study was conducted for class teachers, it may contribute to the results. It is concluded that the science literacy of science teacher candidates can be explained by epistemological beliefs and self-efficacy beliefs in science teaching. In consideration of these results, some measures may be taken and the science literacy of teacher candidates may be increased. Besides, some studies to increase the epistemological beliefs and self-efficacy beliefs in science teaching can be made for raising the science literacy level of student

On the Morphology of the Venom Apparatus of Steatoda paykulliana (Walckenaer, 1806) (Araneae, Theridiidae)

Bu çalışmada, Steatoda paykulliana(Walckenaer,1806)'mn zehir aygıtının morfolojik yapısı taramalı elektron mikroskobu kullanılarak (SEM) incelenmiştir. Prosoma'da yer alan zehir aygıtı, bir çift keliser ile bir çift zehir bezinden oluşmuştur. Keliserlerin her biri, kıllarla kaplı olan şişkin bir kaide parçası ve hareketli bir zehir dişine sahiptir. Dişin uca yakın kısmında bir zehir deliği yer almaktadır. Zehir dişinin hemen altında, bu dişin oturduğu keliser oluğu bulunmaktadır. Bu oluğun uç kısmında biri büyük diğeri küçük iki kutikular diş bulunmaktadır. Zehir bezleri şekil bakımından patlıcanı andırmaktadır. Bezlerin etrafı tamamen çizgili kas lifleri ile sarılmıştır. Bu kas liflerinin kasılmasıyla zehir bezinde üretilen zehir, bir kanal vasıtasıyla zehir dişine gelmekte ve burada yer alan zehir deliğinden dışarıya verilmektedir.:In this study,, the morphological structure of the venom apparatus of Steatoda paykulliana was studied using scanning electron microscopy (SEM). The Venom apparatus situated in the prosoma, is composed of a pair of chelicerae and venom glands. Each chelicera consists of two parts, a stout basal part covered by hair, and a movable fang. A venom pore is situated on the subterminal part of the fang. Just below the fang, there is a cheliceral groove next to the teeth. The end of this groove is covered with one big and another small cuticular teeth. Venom glands are similar to aurbergine in shape. Each gland is completely surrounded by striated muscular fibers. The venom produced in the venom glands reaches to the fang through a canal and is ejected through the venom pore

Structural analysis of pectin, polygalacturonic acid and pectinase enzyme lyophilysed

Pektik enzimler, yüksek moleküler ağırlıklı pektik asitlerin indirgeyici olmayan uçlarına atak yaparak monogalakturonatları oluşturan enzimlerdir. Bu enzimler Saprofltik fungus, bakteri ve bazı mayalarca oluşturulmaktadırlar. Meyve ve sebze teknolojilerinde kullanılmaktadır. Bu çalışmada pektin, poligalakturonik asit ve liyofilize bakteriyel pektinazın kristal yapıları, taramalı elektron mikroskobunda (SEM) görüntülenmiştir. SEM'deki görüntülerinde homojen kristal yapı görülmektedir. Pektin poligalakturonik asit ve bakteriyel pektinaz, elektron ışınlarını geçilmeyecek kadar kompakt ve sıkı paketlenmiştir. Ayrıca substrat moleküllerinin kristallerinin pektinaz enziminden daha küçük boyutta olduğu tespit edilmiştir. Pektinazın enzimatik aktivitesini Ca{} ve Na gibi katyonların sitimüle ettiği bilinmektedir. Çalışmanın ikinci aşamasında pektinaz enziminin kristal yapısında bulunabilecek elementlerin analizi gerçekleştirilmiştir.Pectic substances are pectinic acid, pectin, pectic acid and their salts. Pectin is a polysaccaride found in plants like fruits and vegetables etc in high level. Substances which have no methyl group are pectic acid and polygalacturonic acid. Pectic substances are heteropolysaccarides with 30,000-300,000 molecular weight.Pectic enzymes are known as enzyme destroying chain. Pectic enzymes produce monogalacturonates by attaking the nonreducing end of the high molecular weight pectic acids. These are produced by saprophytic fungi, bacteria and some yeasts. They are used in fruit and vegetable technologies. In this research, crystal structures of pectin, polygalacturonic acid and lyophilysed bacterial pectinase samples were studied by scanning elektron microskop. Homogenous crystal structure was observed from the images at SEM. Pectin, polygalacturonic acid and pectinase enzyme was packed so compact and tightly that no transiion of beam was observed. Pectin crystals have bigger size than polygalacturonic acid crystals. The crystals of substrat molecules was determined to be smaller than pectinase enzymes. Ca and Na cations are known to stimulate enzymatic activity In second step of study, the elements which are thought to be present in the crystal structure of pectinase were analysed. Analysis results showed that Na, Zn and Ca elements were found at concentrations of 60 %, 29.296 % and 6.555 %, respectively

Larinioides cornutus (Araneae, Araneidae) örümceğinin zehir aygıtı üzerine morfolojik bir çalışma

Bu çalışmada, Larinioides cornutus'un zehir aygıtının morfolojik yapısı taramalı electron mikroskobu (SEM) kullanılarak çalışılmıştır. Zehir bezleri, prosomada başın ön kısmında yerleşmiştir ve her bir bez, silindrik kısım ve bir keliseral dişin ucunda sonlanan bitişik bir kanaldan ibarettir. Her bir keliser kıllarla kaplı kalın bir bazal kısım ve hareketli bir zehir dişi olmak üzere iki kısımdan oluşur. Keliseral dişin dorsal yüzeyinde parallel oyuklar yer alır. Ventral yüzey testere dişi gibi oyuklara sahiptir. Zehir dişinin alt kısmında bir zehir açıklığı yerleşmiştir. Zehir dişinin hemen alt kısmında keliser dişlerinin arasında bir keliseral boşluk vardır. Boşluğun herbir kenarı kutikular dişlerle çevrilidir. Zehir bezleri küçük ve şekil bakımından patlıcanı andırmaktadır. Her bir zehir, tamaman çizgili kas lifleriyle çevrelenmiştir. Zehir bezlerinde üretilen zehir, bu kas liflerinin kasılmasıyla bir kanal vasıtasıyla zehir dişine salınmaktadır.The morphological structure of the venom apparatus of L3rinioides cornutus was studied using a scanning electron microscope(SEM). The Venom glands are situated in the anterior cephalic part of the prosoma, and each gland consists of a long cylindrical part and an adjoining duct, which terminates at the tip of the cheliceral fang. Each chelicera consists of 2 parts: a stout basal part covered by hair, and a movable fang. There are parallel grooves on the dorsal surface of the fang. The ventral surface has hollows like saw teeth. A venom pore is situated on the subterminal part of the fang. Below the fang, there is a cheliceral groove between the teeth. Each side of the groove is armed with cuticular teeth. Venom glands are small and similar to an aurbergine in shape. Each gland is surrounded by completely striated muscular fibers. The venom produced in the venom glands is ejected into the fang through the duct by contraction of these muscular fibers

Focusing-free impedimetric differentiation of red blood cells and leukemia cells: A system optimization

Bilican, İsmail ( Aksaray, Yazar )A focusing-free microfluidic impedimetric cell detection system is developed. The effect of the channel dimensions, solution conductivity, excitation voltage, and particle size on impedimetric signal outputs were optimized to increase the sensitivity of the system. Conventional microfabrication techniques were adapted to obtain low height, resealable microchannels. The geometry optimization was performed by a combination of analytical, numerical and experimental approaches. The results demonstrate that reliable impedimetric particle differentiation can be achieved without any labeling or particle focusing. The system parameters were studied and rule-of-thumb design criteria were provided. Finally, using the developed system, red blood cells and leukemia cells were experimentally detected and differentiated. Thanks to its simplicity, the focusing-free cell differentiation system may find applications in several cellular diagnostic uses