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Öğe Investigation of corrosion pattern of AISI 316 and AISI 304 stainless steels in Na2B4O7 center dot 5H(2)O solution(Vserossiiskaya Assotsiatsiya Korrozionistov, 2017) Akgül, Mehmet; Gerengi, Hüsnü; Çamlıbel, Osman; Şahin, M.The corrosion behaviour of AISI 316 and AISI 304 stainless steels in Na2B4O7 center dot 5H(2)O solutions with various concentrations (3%, 6% and 9% w/w) commonly used in wood industry was investigated by using electrochemical impedance spectroscopy and polarisation techniques. The results reveal that the dissolution pattern of the studied steel samples is in the order 3% > 6% > 9%. The AISI 316 stainless steel is found to exhibit better corrosion resistance than the 304-type stainless steel alloy.Öğe A New Product Design After Benckmarking Analysis Of Helis Gear Pumps And Optimization In Energy Consumption(2018) Argun, İrem Düzdar; Kantoğlu, Barış; Öztürk, BurakThe various types of helical gear pumps can be produced to transfer the gasoline, diesel, chemicals, and oil. Helical gear pumps are used by motor power in fuel selling and transfer points, and by gear shafts at mobile transfer trucks. These pumps are classified in three main groups as internal gear, pallet, and helical pumps. The common feature of them is sucking the liquid from the container placed under ground level and transferring it to the high levels. The lower flow rates, noisy working, and the quick corrosion of gear when the pump is running closing outlet valve are the disadvantages of these pumps produced in our country. The aim of this study is to design a new generation of helical gear pump which will eliminate or at least decrease these disadvantages. It is expected to minimize energy consumption, and to protect the corrosion of gears coming from the high pressure at this new design. The dimensions of this pump will be appropriated to the chassis of the truck and at minimum weight. For this reason, benchmarking study is applied; the by-pass system of the pumps that are currently produced, the fluid voids between the teeth, and faults in the inlet-outlet design, and a new type design has been proposed. Besides these the transfer capacity of the pump is increased from 400 l/min to 600 l/min. The energy requirement for 1 liter of liquid is compared with the other products to measure its energy efficiency. The result is also positive at this point of view. Then, this new design is protected by patent registration.Öğe High-level heterologous expression of active Chaetomium thermophilum FDH in Pichia pastoris(Elsevier Inc., 2020) Duman, Zeynep Efsun; Duraksoy, Bedri Burak; Aktaş, Fatih; Woodley, John M.; Binay, BarışNowadays, the use of formate dehydrogenase (FDH, EC 1.17.1.9) is well established as a means of NADH regeneration from NAD+ via the coupled conversion of formate into carbon dioxide. Recent studies have been reported that specifically Chaetomium thermophilum FDH (CtFDH) is the most efficient FDH catalyzing this reaction in reverse (i.e. using CO2 as a substrate to produce formate, and thereby regenerating NAD+). However, to date the production of active CtFDH at high protein expression levels has received relatively little attention. In this study, we have tested the effect of batch and high cell density fermentation (HCDF) strategies in a small stirred fermenter, as well as the effect of supplementing the medium with casamino acids, on the expressed level of secreted CtFDH using P. pastoris. We have established that the amount of expressed CtFDH was indeed enhanced via a HCDF strategy and that extracellular protease activity was eliminated via the addition of casamino acids into the fermentation medium. On this basis, secreted CtFDH in an active form can be easily separated from the fermentation and can be used for subsequent biotechnological applications. © 2020 Elsevier Inc.
