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Öğe N-type InP Schottky diodes with organic thin layer: Electrical and interfacial properties(Journal of Vacuum Science & Technology B, 2010-03) Güllü, Ömer; Turut, AbdulmecitThe rectifying junction characteristics of methyl red (MR) organic film on n-type InP substrate have been studied. It has been observed that MR-based structure shows an excellent rectifying behavior and that the MR film increases the effective barrier height by influencing the space charge region of the n-type InP. The barrier height and ideality factor values for this structure have been obtained as 0.75 eV and 1.93 from the forward bias current-voltage characteristics, respectively. By using capacitance-voltage characteristics at 1 MHz, the barrier height and the carrier concentration values have been calculated as 0.93 eV and 5.13×1015 cm−3, respectively. The energy distributions of the interface states and their relaxation times have been determined from the forward bias capacitance-frequency and conductance-frequency characteristics. Moreover, it was seen that both the interface-state density and the relaxation time of the interface states decreased with bias voltage from experimental results.Öğe Investigation of plasma arc cutting parameters with type-2 fuzzy set and system(De Gruyter, 2013-10) Çelik, Yahya Hışman; Özek, Cebeli; Bulut Özek, MüzeyyenThe objective of the present study was it to design a type-2 fuzzy set and system in order to predict surface roughness and hardness depending on the parameters (material thickness, cutting speed, arc voltage and current) of the plasma arc cutting process of S235JR sheet materials. Therefore, some experimental studies were conducted. The experimentally determined data were used to describe the type-2 fuzzy set and system. Type-2 fuzzy set and system was found to be usefull to predict surface roughnes and hardness. According to the obtained values, the best surface roughness and the values closest to the hardness of the raw material were obtained at 1500 mm/min cutting speed, 8 mm material thickness, 115 V arc voltage and 80 A current.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 A general view to political and economic events causing the collapse of Mamluk State(Energy Education Science&Technology, Part B, 2012-04) Ağır, Abdullah Mesut; Solak, Kemal; Şen, Mehmet Emin; Platin, İhsann this manuscript, the collapse of Mamluk State, which reigned in Egypt and Syria between the years 1250 and 1517 has been studied. Throughout our study, there found different reasons causing this collapse; the most important ones of which are political and economic. The fact that Mamluk System which had crucial role in Mamluk administration Mechanism and the problems lived along its north border are the fundamental collapsing reasons of the state. Indeed, the fights starting with Mongols and Armenians in the north of the state continued with Anatolian Turkmens and Timurids, eventually Ottomans coming from the same direction caused it to be collapsed. Mamluks were the commercial centre between east and west. At the same time, Syria owned a very industrious trade network between Anatolia. However, the geographical discoveries that Europeans carried out and the Portuguese not only military but also commercial activities in the Indian Ocean weakened Mamluks economically. In addition to this, military struggles along the north border of the state caused incompensable deficits in Mamlûk finance. Consequently, when all these negative aspects combined with an unmodernized army, Mamlûk State closed its era in 1517, when Ottoman army defeated it in Reydaniye, which was the end of a 267 year-old-state.Öğe Effects of particle reinforcement on the bending and compressive behaviors of composite pipes(Materials Testing, 2019-11) Adin, HamitIn this study, the effects of adding particles to composite pipes were examined. For the study, composite pipes reinforced with particles were produced by using structural epoxy adhesive and mica as the particle. Composite pipes oriented at [-45 °/+45 °] were manufactured by the hand lay-up method. The composite pipes were loaded axially for measuring bending and compressive strength. When bending and compression loads are applied in the experiments it was seen that the particle reinforced methods indicated in the literature have a great effect of on the strength of the bending and compressive behaviour. The results show that addition of particles enhances compressive and bending strength.Öğe The changes in the serum, liver, kidney protein and genomic DNA profiles in rats treated with 7,12-Dimethylbenz(A) anthracene and Plantago major L.(RJPBCS, 2014-01) Berber, İsmet; Ekin, Suat; Levent, Abdulkadir; Oto, Gökhan;In the study, the changes in the serum, liver, kidney protein and genomic DNA profiles in Wistar albino rats administrated to 7,12-dimethylbenz(a)anthracene (DMBA) and Plantagomajor L. were investigated. SDS-PAGE profiling of the serum proteins showed that the levels of two proteins molecular weighing 140.8 kDa and 46.8 kDa were significantly lower on the 0th day of treatment than on the 60th day of application in the groups. Furthermore, two proteins (34.5 and 22.3 kDa) were solely present in DMBA-treated liver cell lysates. On the contrary, the kidney protein profiles did not show significant banding variations in groups. Genomic DNA analysis also confirmed that DNA extracted from liver and kidney cells did not fragment in any of the groups after the 60th study day. The proteins 34.5 and 22.3 kDa in liver cell lysates at the 60th day in DMBA-treated group could be extra-prognostic indicators for severe DMBA toxicity.Öğe New voltammetric strategy for determination and electrochemical behaviors of metformin by pencil graphite electrode in the NaOH(Indian Chemical Society, 2020) Altunkaynak, Yalçın; Yavuz, Ömer; Levent, AbdulkadirMetformin(MET), an oral antidiabetic drug commonly used in the treatment of diabetes, is a drug that increases insulin sensitivity in the biguanide group [1]. MET shows its pharmacological effect by lowering the glucose level in the blood. In the literature research, there are studies using electrochemical techniques for the analysis of MET in biological fluid and drug forms[1-6]. In this study, the electrochemical properties of MET, one of the drugs used in the treatment of diabetes, were performed using a pencil graphite electrode in NaOH (0.1 M) solution. This compound was recorded with an irreversible and diffusion controlled adsorption oxidation peak at approximately +1.28 V by cyclic voltammetry. With square wave stripping voltammetry, it was observed that the peak current signals of MET in the concentration range of 2.76-24.8 µM in 0.1M NaOH solution increased linearly. At a concentration of 2.76 µM (n = 9), the limit of detection and relative standard deviation were calculated as 9.03 nM (1.495 ngmL-1 ) and 3.25 %, respectively. This method has been successfully applied for MET analysis in pharmaceutical preparations and urine samples without any separation.Öğe Dimension and insulation thickness optimization of circular flat plate solar collectors(Energy Education Science and Technology, 2011) Argunhan, ZekiIn this study, expressions for optimum radius of a circular flat plate solar collector and the optimum insulation thickness distribution are derived by using the concept of solar gain, which maximizes the life-cycle savings. For the specified condition the optimum radius has been found as 2.14 m and the optimum insulation thickness distribution on back of collectors has been formulized. The insulation material thickness distribution has been determined by performing a detailed dimensional analysis; therefore heat loss is minimized, and results are presented in graphics.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 The effects of injection pressure on the engine performance characteristics of a CI engine fueled with canola oil-diesel blends(Energy Education Science and Technology Part A: Energy Science and Research, 2012-01) Aydın, HüseyinThe usage of vegetable oils in diesel engines has some negative effects especially on engine performance. Therefore vegetable oils can not be used as pure form or with high percentages in diesel fuel in unmodified diesel engines. Some of the engine operation conditions should be improved by modifying engine operation systems for this purpose. The effects of injection pressure on engine performance of a diesel engine, by using two different blends of vegetable oil (canola oil) in diesel fuel (DF) having a concentration of 20% (O20) and 50% (O50) vegetable oil, were studied in the present work. The injection pressure was changed from 200 MPa to 220 MPa. Tests were made at fully loaded engine and different speeds of engine operation. In the experiments, the engine power, torque, brake specific fuel consumption (Bsfc), mass fuel consumption rate, brake thermal efficiency and exhaust gas temperature of the test engine have been investigated. Results revealed that the increased injection pressure can significantly promote performance parameters of diesel engine with using vegetable oil without any modification either in oil or in engine itself. The improved results of experiments have been given as graphics in this paper.
