Researcher:
Kızılel, Rıza

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Rıza

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Kızılel

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Kızılel, Rıza

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2012 - 202012

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Now showing 1 - 10 of 12
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    Performance of high capacity Li-ion pouch cells over wide range of operating temperatures and discharge rates
    (Elsevier Science Sa, 2020) N/A; N/A; N/A; Department of Chemical and Biological Engineering; Alipour, Mohammad; Esen, Ekin; Varzeghani, Amir Rahimi; Kızılel, Rıza; PhD Student; PhD Student; PhD Student; Researcher; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 114475
    Operating temperature of Lithium-ion batteries (LIBs) significantly affects their electrochemical-thermal performance, cycle life, and cost. This study presents the thermal and electrochemical performance of 20 Ah LiFePO4 cells for 8 current rates (0.2C-5C) at 8 operating temperatures (-20 degrees C to 50 degrees C). Results show that the effects of operating temperature and current rate on cell performance differ above 10 degrees C, between 10 degrees C and 0 degrees C, and at subzero temperatures. Based on the electrochemical impedance spectroscopy (EIS) measurements, significantly higher bulk and charge-transfer resistances in conjunction with the lower diffusion coefficients results in poor battery efficiency at subzero temperatures. Optimum operating condition is 50 degrees C at a rate of 0.2C, in terms of utilized power and capacity, while a considerable power loss and capacity decrease occur below 20 degrees C. Furthermore, increasing the current rate is detrimental above 0 degrees C, whereas it improves cell performance at -10 degrees C, in terms of cell capacity. Moreover, cell temperature reaches an undesirable value at 50 degrees C and 5C rate, thus a thermal management system is necessary for high capacity LiFePO4 cells at higher temperatures and/or at higher C-rates. Additionally, temperature differences on the surface of high capacity cells reach 10 degrees C below room temperature at high current rates which can lead to nonuniform material utilization, and consequently cell failures. Finally, the cycle life of 20 Ah LiFePO4 cells decreases dramatically as discharge current rate increases. (C) 2020 Elsevier B.V. All rights reserved.
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    Quantification of interactions among circadian clock proteins via surface plasmon resonance
    (Wiley, 2014) N/A; N/A; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Kepsütlü, Burcu; Kızılel, Rıza; Kızılel, Seda; Master Student; Researcher; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 114475; 28376
    Circadian clock is an internal time keeping system recurring 24h daily rhythm in physiology and behavior of organisms. Circadian clock contains transcription and translation feedback loop involving CLOCK/NPaS2, BMaL1, Cry1/2, and Per1/2. in common, heterodimer of CLOCK/NPaS2 and BMaL1 binds to EBOX element in the promoter of Per and Cry genes in order to activate their transcription. CRY and PER making heterodimeric complexes enter the nucleus in order to inhibit their own BMaL1-CLOCK-activated transcription. the aim of this study was to investigate and quantify real-time binding affinities of clock proteins among each other on and off DNa modes using surface plasmon resonance. the pairwise interaction coefficients among clock proteins, As well as interaction of PER2, CRY2, and PER2:CRY2 proteins with BMaL1:CLOCK complex in the presence and absence of EBOX motif have been investigated via analysis of surface plasmon resonance data with pseudo first-order reaction kinetics approximation and via nonlinear regression curve fitting. the results indicated that CRY2 and PER2, BMaL1, and CLOCK proteins form complexes in vitro and that PER2, CRY2 and PER2:CRY2 complex have similar affinities toward BMaL1:CLOCK complex. CRY2 protein had the highest affinity toward EBOX complex, whereas PER2 and CRY2:PER2 complexes displayed low affinity toward EBOX complex. the quantification of the interaction between clock proteins is critical to understand the operation mechanism of the biological clock and to address the behavioral and physiological disorders, and it will be useful for the design of new drugs toward clock-related diseases.
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    Application of the numerical fractionation approach to the design of biofunctional PEG hydrogel membranes
    (Wiley-V C H Verlag Gmbh, 2012) N/A; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Kızılel, Rıza; Kızılel, Seda; Researcher; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; College of Engineering; 114475; 28376
    A mathematical model is described for surface-initiated photopolymerization of PEG-DA forming crosslinked biofunctional PEG hydrogel membranes based on the NF technique. The model includes an additional monomer with biological functionality, which is a common experimental strategy for the design of ECM mimics in tissue engineering in order to direct signaling pathways, and considers concentration-dependent VP propagation and reaction diffusion termination. The influence of these features on the crosslink density of the soluble and gel phases, the progression through gelation, sol/gel fraction, and molecular weight distribution of biofunctional PEG hydrogel are studied using the NF model. This model may be useful for specific applications of tissue engineering.
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    Numerical investigation of design parameters effects on performance of cooling system designed for a lithium-ion cell
    (Yildiz Technical University, 2020) N/A; Department of Chemical and Biological Engineering; Alipour, Mohammad; Kızılel, Rıza; PhD Student; Researcher; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 114475
    A 3D numerical approach using the Finite Element Method (FEM) is applied to model the thermal behavior of multilayer 20Ah LiFePO4/Graphite cell and to design a cooling system. A three-dimensional multilayer cell model with heterogeneous thermal properties for the various cell layers is developed to study the effects of design parameters on cooling performance of mini-channel aluminum plates. As design parameters, effects of channel width, a number of channel passes, inlet mass flow rate, and heat transfer medium were considered. Using the optimized parameters, the cooling performance of water-cooling and air-cooling systems were compared. The results showed that the designed cooling system provided good cooling performance in controlling the temperature rise and uniformity. Inlet mass flow rate was the main influential parameter in controlling the cooling performance. The optimum number of channel passes was found to be seven passes. Channel width mainly controlled the pressure drop and had minor effects on temperature. At higher discharge current rates, the water-cooling system showed better cooling performance in dropping the maximum temperature and making uniform surface and inner temperature profile. Moreover, pressure drop, and power consumption rates become significantly lower for water cooling system.
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    Gelation-stabilized functional composite-modified bitumen for anti-icing purposes
    (Amer Chemical Soc, 2015) Canıaz, Ramazan O.; N/A; N/A; Department of Chemical and Biological Engineering; Aydın, Derya; Kızılel, Rıza; Kızılel, Seda; PhD Student; Researcher; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; N/A; College of Engineering; N/A; 114475; 28376
    Ionic salts as anti-icing agents have been extensively used to eliminate accumulation of ice on asphalt surfaces. However, salt can be easily removed by rain or automobiles and requires frequent application on roads. Besides this economic consideration, anti-icing agents compromise the mechanical properties of asphalt and have a negative impact on living organisms and the environment when used in large amounts. Incorporation of hydrophilic salts into bitumen, a hydrophobic asphalt binder, and controlled release of specific molecules from this hydrophobic medium can provide an effective solution for reducing ice formation on pavements. Bitumen has previously been modified by various polymers, including styrene-butadiene-styrene (SBS) for improved strength and thermomechanical properties. However, an anti-icing function was not considered in those previous designs. In a previous study, we developed a functional polymer composite consisting of potassium formate (HCOOK) salt pockets dissolved in a hydrophilic gel medium and dispersed in a hydrophobic SBS polymer matrix. Here, we developed an innovative method to obtain polymer composite-modified bitumen and investigated further the anti-icing properties of the functional bitumen. We improved incorporation of this polymer composite into bitumen and demonstrated proper distribution of the composite within bitumen through morphological and rheological analysis. We characterized the anti-icing properties of modified bitumen surfaces and demonstrated significant increases in freezing delay of composite-modified bitumen compared to base bitumen in a temperature- and humidity-controlled chamber. In addition, we characterized the release of HCOOK salt from polymer composite-modified bitumen and observed salt release within the range of 1.07-10.8% (w/w) in 67 days, depending on the composite content. The results demonstrate the potential of this polymer composite-modified bitumen for anti-icing functionality and for industrially relevant applications.
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    Investigation of 3-D multilayer approach in predicting the thermal behavior of 20 Ah Li-ion cells
    (Pergamon-Elsevier Science Ltd, 2019) N/A; N/A; Department of Chemical and Biological Engineering; Alipour, Mohammad; Esen, Ekin; Kızılel, Rıza; PhD Student; PhD Student; Researcher; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 114475
    Numerous research groups have adopted a 1D single-layer cell approach to model the thermal behavior of the Li-ion battery systems. However, as the size of a Li-ion cell increases, the 1D single-layer approach is not enough to determine the thermal behavior of the high capacity batteries. In this study, a multilayer approach is proposed to consider the effects of the number of layers on the thermal behavior of the cell. 3D electrochemical-thermal model with multilayer approach is designed and temperature predictions at various discharge rates are calculated. The results are validated at 30 degrees C for various discharge rates. Thermal behavior of the single-layer and multilayer cell approaches are compared with the experimental measurements. The results show that the error of estimates is halved if multilayer approach is applied. The proposed model is also used to study the effects of the number of layers on the temperature non-uniformity of the large sized Li-ion batteries. The results showed that multilayer cell approach represents the thermal behavior of the Li-ion cell more accurately. The study is promising for the development of an efficient thermal management system with a better prediction of the potential hot spots on the single cells and battery packs.
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    Computational and experimental investigation of DNA repair protein photolyase interactions with low molecular weight drugs
    (Wiley-Blackwell, 2013) Marusic, Maja; N/A; N/A; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Azizoğlu, Selimcan; Kızılel, Rıza; Kavaklı, İbrahim Halil; Erman, Burak; Kızılel, Seda; Master Student; Researcher; Faculty Member; Faculty Member; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; College of Engineering; N/A; 114475; 40319; 179997; 28376
    This paper reports the previously unknown interactions between eight low molecular weight commercially available drugs (130800Da) and DNA repair protein photolyase using computational docking simulations and surface plasmon resonance (SPR) experiments. Theoretical dissociation constants, Kd, obtained from molecular docking simulations were compared with the values found from SPR experiments. Among the eight drugs analyzed, computational and experimental values showed similar binding affinities between selected drug and protein pairs. We found no significant differences in binding interactions between pure and commercial forms of the drug lornoxicam and DNA photolyase. Among the eight drugs studied, prednisone, desloratadine, and azelastine exhibited the highest binding affinity (Kd=1.65, 2.05, and 8.47M, respectively) toward DNA photolyase. Results obtained in this study are promising for use in the prediction of unknown interactions of common drugs with specific proteins such as human clock protein cryptochrome. Copyright (c) 2013 John Wiley & Sons, Ltd.
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    Detection of interaction constants between biological clock proteins by Surface Plasmon Resonance
    (AIChE, 2012) Çakır, Bilal; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; N/A; Department of Chemical and Biological Engineering; Kızılel, Seda; Kavaklı, İbrahim Halil; Gidon, Doğan; Asımgil, Hande; Kızılel, Rıza; Kepsütlü, Burcu; Demirer, Gözde Sultan; Faculty Member; Faculty Member; Undergraduated Student; PhD Student; Researcher; Master Student; Undergraduated Student; Department of Chemical and Biological Engineering; College of Engineering; College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; 28376; 40319; N/A; N/A; 114475; N/A; N/A
    Organisms adopt their behaviors and physiology to the appropriate time of the day to anticipate daily environmental changes and the circadian clock regulates their daily rhythms. In mammals, the clock is present in essentially every cell. A heterodimer of CLOCK and BMAL1 proteins binds to the E-box in Per and Cry promoters and activates their transcription. In this work, we have purified core clock proteins and characterized the affinity of previously identified clock-relevant transcription factors. We have investigated the mechanism of the clock complex and the interactions of clock proteins with and without DNA using Surface Plasmon Resonance (SPR). Kinetic parameters determined from real time data bring a solid insight into the interactions of the clock proteins with their cognate promoter.
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    PublicationOpen Access
    Anti-icing properties on surfaces through a functional composite: effect of ionic salts
    (American Chemical Society (ACS), 2018) Department of Mathematics; Aydın, Derya; Akolpoğlu, Mükrime Birgül; Kızılel, Rıza; Kızılel, Seda; Researcher; Master Student; Researcher; Faculty Member; Department of Mathematics; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); College of Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; N/A; 28376
    This study reports the potential of a unique functional composite for anti-icing applications. To date, various ionic salt formulations have been applied to prevent ice accumulation on surfaces. However, salt can be removed by external factors and large amounts must be used to attain anti-icing properties. Incorporating hydrophilic salts into hydrophobic mediums and controlled release of specific agents can provide effective solution to reduce ice accumulation on surfaces. Here, we developed functional polymer composites with salt pockets of altered ionic salts consisting of potassium formate (KCOOH), sodium chloride (NaCl), or magnesium chloride (MgCl2). We dissolved ionic salts in hydrophilic gel domains and dispersed in a hydrophobic styrene-butadiene-styrene polymer matrix. Na+ and Cl- ions delayed ice formation by 42.6 min at -2 degrees C compared to that for unmodified surfaces. Functional composites prepared with the NaCl ionic salt exhibited better anti-icing behavior at -2 degrees C because of their high concentration compared to that of the composites prepared with KCOOH and MgCl2 ionic salts. We also characterized the release of ionic salts from composite-modified hydrophobic medium separately up to 118 days. Furthermore, we monitored freezing of water on composite-incorporated or composite-coated hydrophobic surfaces in a camera-integrated cold chamber with a uniform temperature (-2 degrees C). The results demonstrated significant increases in the delay of freezing on composite-incorporated or composite-coated surfaces compared to that on controls. We observed altered effects of each ionic salt on the mechanical, morphological, and functional properties of the composite-incorporated or composite-coated hydrophobic surfaces. Our results suggested that the efficiency of a polymer composite to promote anti-icing behavior on a surface is directly related to the type and concentration of the particular ionic salt incorporation into the composite. This approach is promising and demonstrates significant potential of the ionic salt embedded within polymer composite-modified hydrophobic surfaces to attain delayed icing function.
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    PublicationOpen Access
    Numerical investigation of design parameters effects on performance of cooling system designed for a lithium-ion cell
    (Yildiz Technical University / Yıldız Teknik Üniversitesi, 2020) Kızılel, Rıza; Alipour, Mohammad; Researcher; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); 114475; N/A
    A 3D numerical approach using the Finite Element Method (FEM) is applied to model the thermal behavior of multilayer 20Ah LiFePO4/Graphite cell and to design a cooling system. A three-dimensional multilayer cell model with heterogeneous thermal properties for the various cell layers is developed to study the effects of design parameters on cooling performance of mini-channel aluminum plates. As design parameters, effects of channel width, a number of channel passes, inlet mass flow rate, and heat transfer medium were considered. Using the optimized parameters, the cooling performance of water-cooling and air-cooling systems were compared. The results showed that the designed cooling system provided good cooling performance in controlling the temperature rise and uniformity. Inlet mass flow rate was the main influential parameter in controlling the cooling performance. The optimum number of channel passes was found to be seven passes. Channel width mainly controlled the pressure drop and had minor effects on temperature. At higher discharge current rates, the water-cooling system showed better cooling performance in dropping the maximum temperature and making uniform surface and inner temperature profile. Moreover, pressure drop, and power consumption rates become significantly lower for water cooling system.