Comprehensive Study of Compact Heat Exchangers with Offset Strip Fin

This chapter is aimed to address the performance of compact heat exchangers with offset strip fin, which have been studied by the researchers in detail for decades. The history and basic features of offset strip fins (OSF) are described first to introduce the fin geometry. Then, the effect of the fin geometry on the performance of the offset strip fin is given from experimental and numerical aspects, respectively. Flow streams evolution under varying offset strip geometries is summarized in order to demonstrate the physical impact on the flow. The thermohydraulic features of the flow in the offset strip fin are investigated by considering the Colburn j‐factor and friction (f) factors in diverse flow regimes. Furthermore the criteria, flow area goodness factor j/f, the ratio j/f1/3 and thermohydraulic performance factor JF, derived from the mentioned dimensionless factors, are also used as a scale of the performance of the structure and reported in the chapter

Comprehensive Study of Heat Exchangers with Louvered Fins

The purpose of this chapter is to describe the basic physical features and the analysis of the thermal-hydraulic performance of the louver fins. The terminology which is used widely in the field of compact heat exchanger with louvered fin is described. The flow phenomenon affected by the operating conditions and the geometric parameters of the louvered fin is examined using the flow visualization techniques found in the literature. A methodology is given to calculate the heat transfer and the friction factor. Stanton number, Colburn j-factor and friction factor are defined as a performance criteria and the variations of these criteria with respect to the Reynolds number and the geometric parameters of the louvered fin. The combinations of these dimensionless number such as area goodness factor (j/f), volume goodness factor (j/f1/3) and JF number related with the volume goodness factor are discussed in terms of overall performance criteria. Finally, the correlations of the louvered fin heat exchanger and their tabulated data was summarized

Türkiye Okul Öncesi Öğretmeleri Profili Araştırması

MakaleWOS:000959740900001The significant technological advances observed in the 21st century and resulting sociological changes require social adaptation. These changes created an essential role for the teachers to instruct the changing qualifications. The present study aimed to determine the profile of preschool teachers in Turkey. Thus, this research was designed as a descriptive study. The study group included 652 teachers. Most of the teachers participating in the research were female participants. Most of the teachers are graduates of pre-school education. However, there are also teachers who have graduated from child development and other fields. The "Turkish Preschool Education Student Profile Questionnaire" developed by Erkan et al. (2001) was adapted by the authors to research the teacher profile. When the findings were examined, it was found that 86% of the teachers participated in educational activities, and these educational activities generally participated in in-service trainings, scientific conferences and cultural events belonging to the ministry; they usually participate in these activities whenever they have the opportunity; the reasons for participating in educational activities are usually due to the lack of time and family situations; It has been determined that the hobbies of teachers are reading books, music, movies, theater and social media. In addition, it was determined that most of the teachers willingly chose pre-school education, as the reason for this, they generally showed that they love children and love to teach. Teachers stated that they volunteered to be a preschool teacher and that they love and care about children. The findings are discussed in the light of the relevant literature. Then recommendations are given.21. yüzyıl ile ortaya çıkan muazzam teknolojik değişim ve buna bağlı olarak gelişen sosyolojik değişim, toplumların bu süreci yaratmasını ve buna uyum sağlamasını zorunlu kılmıştır. Bu süreçte yaşanan değişimin bir sonucu olarak öğretmenler, değişen niteliklerin topluma aktarılmasında önemli bir role sahiptir. Bu araştırma, Türkiye'de çalışmakta olan okul öncesi öğretmenlerinin profilini belirlemeyi amaçlamıştır. Bu amaçla bu araştırma, betimsel araştırma ile desenlendirilmiştir. Çalışma grubu 652 öğretmenden oluşmaktadır. Araştırmaya katılan öğretmenlerin çoğunu kadın katılımcılar oluşturmuştur. Öğretmenlerin çoğu okul öncesi eğitimi mezunudur. Bununla birlikte çocuk gelişimi ve diğer alanlardan mezun olan öğretmenler de mevcuttur. Erkan ve diğerleri tarafından 2001 yılında geliştirilen “Türkiye'de Okul Öncesi Eğitim Öğrenci Profiline Ait Anket” araştırmacılar tarafından uyarlanarak öğretmen profili için uygun hale getirilmiştir. Bulgular incelendiğinde öğretmenlerin %86’sının eğitsel aktivitelere katıldığı, bu eğitsel aktivitelerin genellikle bakanlığa ait hizmet içi eğitimler, bilimsel konferanslar ve kültürel etkinlikler olduğu; bu etkinliklere genellikle fırsat bulduklarında katıldıkları; eğitsel etkinliklere katılma nedenlerinin genellikle zaman bulma sıkıntısı ve ailesel durumlardan kaynaklı olduğu; öğretmenlerin hobilerinin kitap okuma, müzik, film, tiyatro ve sosyal medya şeklinde sıralandığı belirlenmiştir. Ayrıca öğretmenlerin birçoğu isteyerek okul öncesi eğitimi seçtiğini, bunun nedeni olarak da genellikle çocukları ve öğretmeyi sevmelerini belirtmiştir. Öğretmenler, okul öncesi öğretmenliğini isteyerek yaptıklarını, çocukları sevdiklerini ve önemsediklerini belirtmişlerdir. Bulgular ilgili alanyazın ışığında tartışılmıştır. Ardından önerilere yer verilmiştir

Potential effects of metformin in DNA BER system based on oxidative status in type 2 diabetes

Metformin is used to reduce hyperglycemia that induces energetic stress and leads to reduction in gluconeogenesis. Also, metformin inhibits complex I in oxidative phosphorylation, thereby decreasing cellular ATP levels. Activation of AMPK by the reduced ATP levels can induce inhibition of reactive oxygen species (ROS) production and activate p53-mediated DNA repair. DNA polymerase-b and XRCC1 function to repair DNA damages in the BER (base excision repair) system. In type 2 diabetes patients, metformin can enhance AMPK activation therefore suppress oxidative stress. The changes on oxidative stress may alter p53's function and effect many cellular pathways such as; DNA repair. In our project we aim to understand the effects of metformin on p53 and DNA-BER system based on the oxidative status in type 2 diabetes patients. Oxidative and antioxidative capacity, catalase, SOD, GPx activities and, DNA pol beta, XRCC1 and p53 levels were measured in metformin using or non-using type 2 diabetes patients and controls. Metformin enhanced SOD and GPx activities in type 2 diabetes patients but the reflection of this increase to the total antioxidant capacity was not significant. Although the increase in DNA pol beta was not significant, XRCC1 and p53 levels were significantly upregulated with metformin treatment in type 2 diabetes patients. Our study reinforces the potential benefit of metformin in antioxidative capacity to protect cells from diabetic oxidative stress and in regulation of DNA BER system

Postmenapozal osteoporozisli hastalarda farklı tedavilerin karşılaştırılması

TEZ2332Tez (Uzmanlık) -- Çukurova Üniversitesi, Adana, 1997.Kaynakça (s. 47-52) var.52 s. ; 30 cm.