https://hdl.handle.net/11436/61 Fri, 25 Sep 2026 01:34:49 GMT 2026-09-25T01:34:49Z https://hdl.handle.net/11436/10944 Investigation of structural, hardness, adhesion, and tribological properties of CrN and AlCrN coatings deposited on cylinder liner Aktarer, Semih Mahmut; Sert, Yaşar; Küçükömeroğlu, Tevfik Friction between cylinder liners and piston rings is one of the major energy losses in engines. Minimizing this friction reduces fuel consumption, lowers emissions, and enhances performance. To address this, CrN and AlCrN coatings were applied to grey cast iron (GCI) cylinder liners using cathodic arc deposition method. Their tribological properties were evaluated under varying loads through reciprocating wear tests in dry and lubricated conditions. The structure of the coatings was characterized by electron microscopy (SEM-EDS) and X-ray diffraction (XRD), while the hardness and adhesion properties were characterized by nanoindentation and scratch testing. The CrN coating showed 21% lower hardness but 18% higher adhesion strength and superior crack resistance compared to AlCrN. In dry, low-load conditions, AlCrN's higher hardness resulted in 30% better wear resistance. However, under high-load conditions, the wear resistance of CrN coating is about 3 times higher than AlCrN coating due to its improved adhesion properties. CrN and AlCrN coatings reduced wear rates by approximately 70 and 24 times, respectively, compared to GCI. In lubricated conditions, CrN's wear rate was 5.3 times lower than GCI and 2.4 times lower than AlCrN. These findings show that AlCrN is ideal under low loads, while CrN is better for high-loads. Wed, 01 Jan 2025 00:00:00 GMT https://hdl.handle.net/11436/10944 2025-01-01T00:00:00Z https://hdl.handle.net/11436/10918 Selection, heterologous production, and functional characterization of a thermostable xylanase from anoxybacillus for dough and bread quality enhancement Karaoğlu, Hakan; Ramadan, Khaled M.A.; Al Hashedi, Sallah A.; AlShoaibi, Adil; Iqbal, Zafar; Aydın, Rukiye; Secgin, Busra Abanoz; Seçgin, Zafer; Bendary, Eslam S.A.; Mahmoud, Mohamed A.A.; Emanet, Züleyha Akpınar; Efe, Derya Thermostable xylanases contribute to enhancing dough properties and bread quality in industrial baking. This study aimed to identify a high-yield thermophilic xylanase producer, optimize its heterologous expression, and evaluate its functional role in baking applications. Screening of 19 Anoxybacillus species identified A. bogrovensis as the highest xylanase producer. The xyn gene was cloned and expressed in Escherichia coli BL21, and the recombinant enzyme (iAboXYN) was purified using heat treatment, ion-exchange, and hydrophobic interaction chromatography. Biochemical characterization confirmed high thermal and pH stability, with over 50 % activity retained up to 80 °C and moderate stability observed at 90 °C, along with broad pH adaptability (5.0-8.5) and metal ion resistance. The enzyme's functional role in dough processing was assessed using a direct dose-response analysis, demonstrating improvements in dough stability, elasticity, and hydration efficiency while reducing mixing time and water absorption. Application in bread formulations led to enhanced loaf volume, improved crumb structure, and better texture, with sensory evaluation confirming superior quality. Preference ranking tests further validated the improved consumer perception of iAboXYN-treated bread. These findings establish iAboXYN as a functional biocatalyst for enzyme-assisted baking, offering a scalable approach to optimizing dough properties and improving bread quality. Wed, 01 Jan 2025 00:00:00 GMT https://hdl.handle.net/11436/10918 2025-01-01T00:00:00Z https://hdl.handle.net/11436/10871 Historically low microplastic loads within white bream (Blicca bjoerkna) in the Marmara basin, Türkiye Kurtul, Irmak; Parker, Ben; Bayçelebi, Esra; Oral Kaba, Münevver; Kaya, Cüneyt; Mutlu, Tanju; Akalın, Sencer; Gedik, Kenan; Haubrock, Phillip J.; Tarkan, Ali Serhan; Britton, J. Robert Assessment of 154 white bream Blicca bjoerkna specimens collected between 1963 and 2004 from Manyas and Uluabat lake, northwest Türkiye, revealed that only 3.2% of fish were contaminated with microplastics, with a mean incidence and standard error of 0.04 ± 0.02 particles. Black fibres and white fragments were spectroscopically confirmed as polyamide and polyethylene terephthalate. Contamination status (contaminated/uncontaminated) of individuals was unrelated to Fulton's condition factor, lake, sampling year and sex. Results thus highlight the utility of historical collection specimens in assessing temporal microplastic contamination within freshwater fishes. Wed, 01 Jan 2025 00:00:00 GMT https://hdl.handle.net/11436/10871 2025-01-01T00:00:00Z https://hdl.handle.net/11436/10868 Effect of high-entropy alloy amount on microstructural and mechanical properties of metal matrix composites fabricated via friction stir processing Sekban, Dursun Murat; Özkaya, Serdar; Yanar, Harun; Karabacak, Abdullah Hasan; Aktarer, Semih Mahmut; Coşkun, Abdulkadir Metal matrix composites (MMCs) produced by using high-entropy alloy (HEA) powders as reinforcements exhibit superior mechanical properties. In this study, the microstructure, mechanical properties, wear, and corrosive behavior of Al7075/HEA MMCs produced by friction stir processing (FSP) using HEA powders at various ratios (5% and 10%) are systematically investigated. The effect of FSP and HEA powders leads to a grain size reduction of about 23%. The hardness of the MMC structure shows a significant improvement, increasing by 129% compared to the base material. The tensile strength increases by about 46%. Compared to the base material, MMCs containing 10% HEA have a corrosion resistance about 82% higher. While wear resistance is adversely affected by FSP alone, the addition of HEA powders alleviates this disadvantage. Compared to specimens exposed to FSP alone, HEA reinforcement improves the wear performance. Despite the improvements in strength and hardness, elongation values decrease in MMCs. The findings indicate that HEA-reinforced Al7075 MMCs with an ideal combination of strength, hardness, and corrosion resistance make them promising candidates for structural applications requiring superior mechanical properties. Wed, 01 Jan 2025 00:00:00 GMT https://hdl.handle.net/11436/10868 2025-01-01T00:00:00Z