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Öğe An exergy analysis of a concentric tube heat exchanger using hBN-water nanofluids(Inder Science Publishers, 2021) Budak Ziyadanoğulları, Neşe; Perçin, SüleymanThis study investigated the effects of using nanofluids prepared with hexagonal boron nitride (hBN) nanoparticles on the thermal performance and pressure drop of a concentric tube heat exchanger. Experiments were carried out with water-hBN nanofluids for stable, dispersed, 0.01%, 0.1% and 1% volume concentrations, at different flow rates and Reynolds numbers under parallel and counter-flow conditions. When the experimental results were examined, the exergy loss was higher in the parallel-flow heat exchanger compared to the counter-flow heat exchanger. The highest exergy loss value was obtained for distilled water at the highest Reynolds number (Re = 8,700) for parallel flow operation at 170 W. The exergy loss of water at the highest Reynolds number (Re = 8,700) for parallel flow operation increased by 15.7%, 24.8% and 49.8% for hBN-water concentrations of 0.01%, 0.1% and 1%, respectively. Exergy loss of water at the highest Reynold number (Re = 8,700) for counter flow operation increased by 11.3%, 17.3% and 29.2% for hBN-water concentrations of 0.01%, 0.1% and 1%, respectively. When evaluating the exergy analysis of the system, exergy losses due to pressure drops were negligible for both flows (parallel and counter).Öğe An experimental investigation of the effect of thermophysical properties on time lag and decrement factor for building elements(Gazi University, 2020-06-01) Oktay, Hasan; Yumrutaş, Recep; Argunhan, ZekiThe time lag (TL) and decrement factor (DF) are essential for the heat storage capabilities of building elements, which strictly depend on the thermophysical properties of the elements. Many investigations are presented in literature arguing to find the influence of each thermophysical property on TL and DF by keeping the other properties constant. This study aims to investigate the effect of each property on TL and DF, utilizing relationships between the measurement values of the thermophysical properties of wall materials. Therefore, first, 132 new concrete wall samples were produced, and their thermophysical properties were tested. Secondly, TL and DF values for each building element are computed from the solution of the problem by Complex Finite Fourier Transform (CFFT) technique. Finally, a multivariate regression analysis has been performed, and the variations of each thermophysical property versus TL and DF are presented, and also the findings are compared with literature. The results show that each property alone (keeping the other properties constant) is not adequate to identify the thermal inertia and thermal performance of a wall element. Besides, 87.3 % decrease in thermal diffusivity corresponds to 6.03 h increase in the value of TL and 88.8 % decrease in value of DF; respectively, for W1 wall assembly.Öğe The effect of intrapreneurship and organizational factors on the innovation performance in hospital(Expert Projects, 2018-09) Ekingen, Erhan; Ekemen, Mehmet Ali; Yıldız, Ahmet; Korkmazer, FuatIn the context of environmental uncertainty and competition, organizations are trying to find new ways to improve their performance. The development of novelties based on innovation, especially in the service sector, is the departure point for many organizations. Intrapreneurship and organizational structure are important factors for organizations to improve the innovation performance. In this study, it is aimed to investigate whether intrapreneurship and organizational factors influence the innovation performance. The data were collected from a hospital by means of intrapreneurship scale, organizational factors scale and innovation performance scale. According to the results of Structural Equation Model analysis, intrapreneurship has positive influences on innovation performance. Organizational factors directly and indirectly affect innovation performance. Moreover, intrapreneurship has mediation effect between organizational factors and innovation performance. Lastly, Intrapreneurship enhances the effect of organizational factors on innovation performance.Öğe Finite element analysis of the stress distributions in peri-implant bone in modified and standard-threaded dental implants(Taylor & Francis, 2016-01) Topkaya, Tolga; Dündar, Serkan; Solmaz, Murat Yavuz; Yaman, Ferhan; Atalay, Yusuf; Saybak, Arif; Asutay, Fatih; Çakmak, ÖmerThe aim of this study was to examine the stress distributions with three different loads in two different geometric and threaded types of dental implants by finite element analysis. For this purpose, two different implant models, Nobel Replace and Nobel Active (Nobel Biocare, Zurich, Switzerland), which are currently used in clinical cases, were constructed by using ANSYS Workbench 12.1. The stress distributions on components of the implant system under three different static loadings were analysed for the two models. The maximum stress values that occurred in all components were observed in FIII (300 N). The maximum stress values occurred in FIII (300 N) when the Nobel Replace implant is used, whereas the lowest ones, in the case of FI (150 N) loading in the Nobel Active implant. In all models, the maximum tensions were observed to be in the neck region of the implants. Increasing the connection between the implant and the bone surface may allow more uniform distribution of the forces of the dental implant and may protect the bone around the implant. Thus, the implant could remain in the mouth for longer periods. Variable-thread tapered implants can increase the implant and bone contact.Öğe Synthesis, characterization and antioxidant activity of heterocyclic Schiff bases(Journal of the Chinese Chemical Society, 2020-08-04) Aral, Tarık; Dağ, Beşir; Kızılkaya, Hakan; Genç, Nusret; Erenler, RamazanSchiff base derivatives have gained great importance due to revealing a great number of biological properties. Schiff bases were synthesized by treatment of 4-amino-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (1) with various aldehydes in methanol at reflux. In addition, diamine was reacted with an aldehyde to yield the corresponding Schiff bases. The structures of synthesized Schiff bases were elucidated by spectroscopic methods such as microanalysis, 1 H-NMR, 13C-NMR, and FTIR. Antioxidant activities of synthesized Schiff bases were carried out using different antioxidant assays such as 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH• ) scavenging, 2,20 -azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging, and reducing power activity. (E)-4-((1H-indol-3-yl)methyleneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (3), (E)-1,5-dimethyl-4-((2-methyl-1H-indol-3-yl) methyleneamino)-2-phenyl-1H-pyrazol-3(2H)-one (5), (E)-1,5-dimethyl-2-phenyl-4-(thiophen-2-ylmethyleneamino)-1H-pyrazol-3(2H)-one (7), (E)-1,5-dimethyl2-phenyl-4-(quinolin-2-ylmethyleneamino)-1H-pyrazol-3(2H)-one (9), (1S,2S, N1,N2)-N1,N2-bis((1H-indol-3-yl)methylene)cyclohexane-1,2-diamine (11), and (1S,2S,N1,N2)-N1,N2-bis((2-methyl-1H-indol-3-yl)methylene)cyclohexane-1,2-diamine (12) were synthesized in high yields. Compound 5 displayed a good ABTS•+ activity. Compound 3 revealed the outstanding activity in all assays. Compound 7 has the best-reducing power ability in comparison to other synthesized compounds. Although compounds 5, 11, 12 are new, compounds 3, 7, 9 are known. Due to revealing a good antioxidant activity, the synthesized compounds (3, 5, 7) have the potential to be used as synthetic antioxidant agents.Öğe Plantago major protective effects on antioxidant status after administration of 7,12-dimethylbenz(a)anthracene in rats(Asian Pacific Organization for Cancer Prevention, 2011) Oto, Gökhan; Ekin, Suat; Özdemir, Hülya; Demir, Halit; Yaşar, Semih; Levent, Abdulkadir; Berber, İsmet; Kaki, BarışAim: The present study was designed to evaluate effects of Plantago major extract on oxidative status in Wistar albino rats administrated 7,12-dimethylbenz(a)anthracene (DMBA). Methods: Rats were divided into three equal groups of 6 animals each: Group 1 controls, group 2 treated with DMBA (100 mg/kg, single dose) and group 3 receiving the DMBA and the aqueous extract at 100 mg/kg/d for 60 days. Results: Significant decrease in catalase (P<0.05), carbonic anhydrase (p≤0.01), reduced glutathione (GSH) (P<0.01) and total protein (P<0.01) values was observed in the DMBA group compared with the healthy controls and DMBA + Plantago major groups. Conclusion: The results suggest preventive effects of Plantago major on DMBA induced oxidative damage in Wistar albino rats that might be due to decreased free radical generation.Öğe “Balcı” aspir (Carthamus tinctorius l.) çeşidinin in vitro sürgün uçlarının mikroçoğaltımı ve köklendirilmesi üzerine oksin ve sitokininlerin etkisi(Yüzüncü Yıl Üniversitesi, 2018-12-31) Akbaş, Filiz; Hamidi Birecikli, AtikeBu çalışmada, linoleik tipte olan Balcı aspir çeşidinin, mikroçoğaltımı ve köklendirilmesi üzerine bazı sitokinin (BAP ve Kin) ve oksinlerin (NAA ve IAA) etkisi incelenerek in vitro çoğaltım protokolünün geliştirilmesi amaçlanmıştır. Başlangıç materyali olarak, in vitro koşullarda çimlendirilen olgun tohumlardan elde edilen steril fidelerin sürgün uçları kullanılmıştır. Sürgün uçları mikroçoğaltım için, BAP ve Kin’in farklı konsantrasyonlarının (0.0, 0.5, 1.0, 2.0 ve 4.0 mg/L) bulunduğu MS besi ortamında kültüre alınmıştır. Elde edilen sürgünler köklendirme aşamasında farklı NAA ve IAA (0.0, 0.5, 1.0 ve 2.0 mg/L) konsantrasyonlarını içeren MS besi ortamına transfer edilmiştir. BAP konsantrasyonları arasında en iyi sürgün çoğaltımı, eksplant başına 5.33 adet sürgün ile 0.5 mg/L BAP’lı ortamdan elde edilirken, Kin uygulamalarında ise 3.75 adet sürgün ile 0.5 mg/L Kin ve 3.33 adet sürgün ile 4.0 mg/L Kin içeren ortamdan elde edilmiştir. Ancak BAP uygulamalarının genelinde ve 4.0 mg/L Kin uygulamasında oluşan sürgünlerde vitrifikasyon olduğu belirlenmiştir. Bu nedenle, 0.5 mg/L Kin ile desteklenmiş MS besi ortamının Balcı aspir çeşidinin in vitro sürgün çoğaltımı için en ideal ortam olduğu tespit edilmiştir. En iyi kök oluşumunun, eksplant başına 20 adet ile 2.0 mg/L NAA içeren ortamda kültüre alınan sürgünlerde olduğu saptanmıştır. Elde edilen köklü fideler torf – perlit karışımı içeren saksılara dikilerek toprağa adaptasyonu sağlanmıştır.Öğe Exhaust emissions of methanol and ethanol-unleaded gasoline blends in a spark ignition engine(VINCA Institute of Nuclear Sciences, 2013) Altun, Şehmus; Öztop, Hakan Fehmi; Öner, Cengiz; Varol, YasinIn this study, the effect of unleaded gasoline and unleaded gasoline blended with 5% and 10% of ethanol or methanol on the performance and exhaust emissions of a spark-ignition engine were experimentally investigated. The engine tests were performed by varying the engine speed between 1000 and 4000 rpm with 500 rpm period at three-fourth throttle opening position. The results showed that brake specific fuel consumption increased while brake thermal efficiency, emissions of carbon monoxide and hydrocarbon decreased with methanol-unleaded gasoline and ethanol-unleaded gasoline blends. It was found that a 10% blend of ethanol or methanol with unleaded gasoline works well in the existing design of engine and parameters at which engines are operating.Öğe Geçmişten günümüze kalan bir tartışma ve forum dergisi çevresinde gelişen edebi bir hareket(Türkbilig, 2014-06-01) Korkmaz, FerhatOsmanlı İmparatorluğu’nun son dönemleriyle Cumhuriyetin ilk yıllarında Türk edebiyatı edebi muhitler ve hareketler bakımından son derece zengindir. Araştırmacılar tarafından Demokrat Parti dönemi olarak adlandırılan 1950-1960 yılları arasında, İkinci Yeni hareketi ile birlikte var olmuş başka bir edebi hareketin adı “Forum Çevresi”dir. Türk medeniyetinin Batı medeniyeti ile sentezini savunan “Forum Çevresi”, özellikle roman ve hikâye türlerinde verdikleri eserlerle adlarını duyurmak istemişlerdir. Batı edebiyatından T. S. Eliot, James Joyce, Franz Kafka, Virginia Woolf ve Marcel Proust gibi modern edebiyat temsilcileri olan şair, öykücü ve romancıların etkisiyle eser vermeyi hedefleyen “Forum Çevresi” tıpkı takip ettikleri sanatçılar gibi modernist bir edebi hareket kurmuşlardır. Hareketin savunucusu Metin And’dır. Bilge Karasu, Feyyaz Kayacan, Mehmet Başaran ve Oktay Rifat hareketin görüşlerine bağlı olarak eser vermişlerdir. “Forum Çevresi”ni oluşturan şair ve yazarlar, genellikle Forum, Yenilik ve Pazar Postası yayımları etrafında eser vermişlerdirÖğe First boundary value problem for cordes-type semilinear parabolic equation with discontinuous coefficients(Hindawi, 2020-06-19) Harman, Aziz; Harman, EzgiFor a class of semilinear parabolic equations with discontinuous coefficients, the strong solvability of the Dirichlet problem is studied in this paper. The problem ∑i,j=1naijt,xuxixj-ut+gt,x,u=ft,x,uΓQT=0, in QT=Ω×0,T is the subject of our study, where Ω is bounded C2 or a convex subdomain of En+1,ΓQT=∂QT\∖t=T. The function gx,u is assumed to be a Caratheodory function satisfying the growth condition gt,x,u≤b0uq, for b0>0,q∈0,n+1/n-1,n≥2, and leading coefficients satisfy Cordes condition b0>0,q∈0,n+1/n-1,n≥2.
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