Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 8Citation - Scopus: 9Experimental Investigation of Air Cooling With/Out Tab Cooling in Cell and Module Levels for Thermal Uniformity in Battery Packs(ASME, 2023) Göçmen, Sinan; Çetkin, ErdalCatastrophic effects of global warming and environmental pollution are becoming more evident each day, and reduction in fossil fuel consumption is an urgent need. Thus, electric vehicles powered by sustainable energy sources are becoming a major interest. However, there are some challenges such as safety, limited range, long charging times, and battery life which are inhibitory to the adaptation of them. One of the biggest reasons for these challenges is the relationship between battery degradation and temperature which can be eliminated if batteries can be kept at the optimum temperature range. Here, the effects of three distinct (natural convection, forced convection, and tab cooling) methodology were experimentally compared at both the cell and module levels (six serial 7.5 Ah Kokam pouch cells, 1P6S) for thermal management of lithium-ion cells. The experiments were conducted at a discharge rate of 3C with ambient temperatures of 24 ◦C and 29 ◦C. The cell-level test results show that the tab cooling yields 32.5% better thermal uniformity in comparison to the other techniques. Furthermore, tab cooling yields better temperature uniformity with and without air convection as the hot spots occurring near the tabs is eliminated. For the module level, the forced air convection method stands out as the best option with a 4.3% temperature deviation between cells and maximum cell temperature of 39 ◦C. Overall, the results show that a hybrid approach with tab cooling would be beneficial in terms of temperature homogeneity especially in high capacity electric vehicle battery cells.Book Part Impacts of Remediation of Halogenated Organic Compounds in Soils and Sediments(IGI Global, 2022) Demirtepe, HaleHalogenated hydrophobic organic compounds (HOCs) have been used in various industrial applications and are present in many commercial products. Due to their emissions during manufacturing and discharges as wastes, halogenated HOCs such as polychlorinated biphenyls and polybrominated diphenyl ethers are ubiquitously found in the environment and create contaminated sites. To remove the contamination from these sites, various remediation techniques have been useful. The purpose of this chapter is to investigate the impacts of traditional and emerging remediation techniques on ecosystem. One of the traditional remediation techniques is dredging and the mostly studied emerging remediation techniques are bioaugmentation and biostimulation. The efficiency of these techniques is also evaluated regarding reduction in contaminant mass. Overall, this chapter presents the efficiency and possible impacts of dredging, bioaugmentation and biostimulation of soils and sediments, and the implications include the evaluation of most feasible remediation techniques by using life cycle assessment.Book Part Citation - Scopus: 32Language of Response Surface Methodology as an Experimental Strategy for Electrochemical Wastewater Treatment Process Optimization(Elsevier, 2022) Gören, Ayşegül Yağmur; Recepoğlu, Yaşar Kemal; Khataee, AlirezaThe availability and accessibility to safe and secure water resources are the key technological and scientific concerns of global significance. As a result of water scarcity worldwide, wastewater treatment and reuse are considered viable options to replace freshwater resources in agricultural irrigation and domestic and industrial purposes. A significant need for clean water has promoted the invention and/or enhancement of several electrochemical wastewater treatment (EWT) processes. Optimization of the process variables plays a crucial role in wastewater treatment to enhance technology performance, considering removal efficiency, operating cost, and environmental impacts. These processes are fundamentally complex multivariable, and the optimization through conventional methods is unreliable, inflexible, and time- and material-consuming. In this perspective, response surface methodology (RSM) appears to be a beneficial statistical experimental strategy for the performance optimization of the EWT process. This model could be utilized for the optimization and analysis of the individual and/or combined effects of operational variables on the treatment process to improve the system performance. Furthermore, this model provides a number of information from a slight number of experimental trials. In this chapter, a summary and a discussion are presented on the RSM model used in the electrochemical wastewater treatment processes to overcome process crucial challenges toward the optimization and modeling of process parameters. It provides a potential model to enhance the various types of wastewater treatment process performance with effective optimization. Overall, it is described that the RSM model can be used in EWT processes to find the optimum conditions.Article Citation - WoS: 5Citation - Scopus: 6Undescribed Polyether Ionophores From Streptomyces Cacaoi and Their Antibacterial and Antiproliferative Activities(Elsevier, 2022) Gezer, Emre; Üner, Göklem; Küçüksolak, Melis; Kurt, Mustafa Ünver; Doğan, Gamze; Ballar Kırmızıbayrak, Petek; Bedir, ErdalPolyether ionophores represent a large group of naturally occurring compounds mainly produced by Streptomyces species. With previously proven varieties of bioactivity including antibacterial, antifungal, antiparasitic, antiviral and anti-tumor effects, the discovery of undescribed polyethers leading to development of efficient therapeutics has become important. As part of our research on polyether-rich Streptomyces cacaoi, we previously performed modification studies on fermentation conditions to induce synthesis of specialized metabolites. Here, we report four undescribed and nine known polyether compounds from S. cacaoi grown in optimized conditions. Antimicrobial activity assays revealed that four compounds, including the undescribed (6), showed strong inhibitory effects over both Bacillus subtilis and methicillin-resistant Staphylococcus aureus (MRSA) growth. Additionally, K41-A and its C15-demethoxy derivative exhibited significant cytotoxicity. These results signified that selectivity of C15-demethoxy K41-A towards cancer cells was higher than K41-A, which prompted us to conduct mechanistic experiments. These studies showed that this uninvestigated compound acts as a multitarget compound by inhibiting autophagic flux, inducing reactive oxygen species formation, abolishing proteasome activity, and stimulating ER stress. Consequently, the optimized fermentation conditions of S. cacaoi led to the isolation of undescribed and known polyethers displaying promising activities.Article Citation - WoS: 30Citation - Scopus: 30Thermal Retrofitting for Sustainable Use of Traditional Dwellings in Mediterranean Climate of Southwestern Anatolia(Elsevier, 2022) Timur, Barış Ali; Başaran, Tahsin; İpekoğlu, BaşakThermal retrofitting implementations are crucial for safeguarding the functional sustainability of historical buildings as they can improve the thermal performance of these buildings while maintaining thermal comfort for their occupants. This study aims to examine the thermal behavior of a common historical building type in Anatolia / Turkey, the traditional houses with exterior hall (sofa), and to determine enhancement potentials of possible thermal interventions. Research method consists of on-site thermal measurements, laboratory analyses on traditional construction materials and transient thermal analyses utilizing simulations on DesignBuilder software. Study cases were selected from both urban and rural sub-settlements. The results demonstrated that the thermal insulation works within floor assemblies, airtightness measures, adding secondary glazing to windows and suggesting transparent circulation corridors provide significant energy improvements. These interventions would save 26.5% of building energy consumption in the urban and 30.4% in the rural sub-settlements when applied together. Furthermore, when the integration of a modern HVAC system, ground-source heat pump is implemented, these improvement rates can be increased to more than 60%. Consequently, it was determined that the cases have significant potentials for thermal enhancements which renders the application of thermal interventions as a capable conservation tool.Article Citation - WoS: 9Citation - Scopus: 9How Does Arsenic Speciation (arsenite and Arsenate) in Groundwater Affect the Performance of an Aerated Electrocoagulation Reactor and Human Health Risk?(Elsevier, 2022) Gören, Ayşegül Yağmur; Kobya, Mehmet; Khataee, AlirezaArsenic (As) occurrence in water resources has become one of the most critical environmental problems worldwide. The detrimental health impacts on humans have been reported due to the consumption of As-contaminated groundwater resources. Consumption of As-containing water over the long term can cause arsenicosis and chronic effects on human health due to its toxicity. Several treatment processes are available for As removals such as coagulation, ion exchange, adsorption, and membrane technologies but they have various major drawbacks. In the present work, therefore, an aerated electrocoagulation (EC) system with aluminum anodes was operated for simultaneous arsenate (As(V)) and arsenite (As(III)) removal to overcome the disadvantages of other processes such as, sludge formation, difficulties in operation, high operating costs, high energy consumption, and the requirement of pre-treatment process and to enhance the conventional EC process. The combined effects of the applied current (0.075–0.3 A), aeration rate (0–6 L/min), pH (6.5–8.5), and As speciation (As(V)-As(III)) were studied on As removal efficiency. The findings revealed that As removal mostly depended on the airflow rate and the applied current in the EC system. The highest As removal efficiency (99.1%) was obtained at an airflow rate of 6 L/min, a pH of 6.5, an initial As (V) concentration of 200 μg/L, and a current of 0.3 A, with an energy consumption of 2.85 kWh/m3 and an operating cost of 0.66 $/m3. The human health risk assessment of treated water was also examined to understand the performance of the EC system. At most of the experimental runs, the chronic toxic risk (CTR) and carcinogenic risk (CR) of As were within the permissible limits except for an airflow rate of 0–2 L/min, an initial pH of 8.5, and a current of 0.075–0.15 A for high initial As (III) concentrations. Overall, the As removal performance and groundwater risk assessment show that the EC process is a promising option for industrial applications.Article Citation - WoS: 9Citation - Scopus: 7Understanding the Impact of Sri2 Additive on the Properties of Sn-Based Halide Perovskites(Elsevier, 2022) Yüce, Hürriyet; Perini, Carlo A. R.; Hidalgo, Juanita; Castro-Mendez, Andres-Felipe; Evans, Caria; Demir, Mustafa MuammerOrganic-inorganic halide perovskites have been identified as favorable candidates for the next generation of photovoltaics. Adding alkali metal halides to perovskite films has been shown to be a viable option to improve the perovskite film quality and to modulate their fundamental properties. In this work, we perform optical and electron-beam based characterizations of mixed Sn/Pb based perovskite films to investigate the effect of the addition of the alkaline metal halide SrI2. By analyzing structural (X-ray diffraction), morphological (Scanning Electron Microscopy), optical (photoluminescence), and chemical properties (X-ray photoelectron spectroscopy), we show a complex interplay of effects upon addition of Sr2+ into the perovskite solution. Low concentrations of Sr2+ increases lattice strain, which hints at incorporation of the additive into the perovskite lattice and improves the film optoelectronic properties. As the additive concentration increases beyond 0.5 mol %, microstrain decreases. At concentrations >0.5 mol %, Sr2+ induces significant reduction of the average domain size, which impacts both structural and optical properties of the perovskite film.Article Citation - WoS: 1Dedekind Harmonic Numbers(Indian Academy of Sciences, 2021) Altuntaş, Çağatay; Göral, HaydarFor any number field, we define Dedekind harmonic numbers with respect to this number field. First, we show that they are not integers except finitely many of them. Then, we present a uniform and an explicit version of this result for quadratic number fields. Moreover, by assuming the Riemann hypothesis for Dedekind zeta functions, we prove that the difference of two Dedekind harmonic numbers are not integers after a while if we have enough terms, and we prove the non-integrality of Dedekind harmonic numbers for quadratic number fields in another uniform way together with an asymptotic result.