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MakaleAçık Erişim2022Scopus SJRQ1/r/munzur/2609
Keller box simulation of magnetic pseudoplastic nano-polymer coating flow over a circular cylinder with entropy optimisation
Al-Mdallal, Qasem; Prasad, V. Ramachandra; Basha, H. Thameem; Sarris, Ioannis; Akkurt, Nevzat
In this study, a Keller box calculation of magnetic nanopolymer coating flow over a circular cylinder in the presence of nonlinear convection is performed. A two-phase nanofluid model (Buongiorno model) is used to model the equations for nanofluid flow and heat and mass transfer. The problem at hand is first formulated in the dimensional form of nonlinear partial differential equations (PDEs) and then transformed into the dimensionless PDEs form by manipulating non-similar variables. The Keller box approach (implicit finite differences) is used for the calculations of the transformed PDEs. The characteristics of critical thermophysical physical parameters on the flow field, viz thermal convection, Brownian motion, Weissenberg number, thermophoresis, magnetic field, heat source/sink, Biot number, buoyancy ration parameter, Eckert number, and mixed convection, are graphically manifested. In addition, the flow control parameters estimate the sheath friction, heat transfer rate, and mass transfer rate in the flow coordinate. A significant increase in the velocity of the Williamson nanofluid is accompanied by an increase in the Biot number, magnetic field, and mixed convection. The isotherms show a higher fluid temperature near the wall in the absence of convection. The Weissenberg number, Biot number, and thermophoresis significantly increase the temperature of the Williamson nanofluid. The density of the streamlines is lowered with a larger buoyancy ratio parameter. The total entropy generation of the Williamson nanofluid is improved by increasing the Brinkman number and the Weissenberg number.
AtıfScopus35OpenAlex35
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MakaleAçık Erişim2022Scopus SJRQ1/r/munzur/2566
High-temperature and abrasion resistance of self-compacting mortars incorporating binary and ternary blends of silica fume and slag
Yön, Merve Şahin; Arslan, Furkan; Karatas, Mehmet; Benli, Ahmet
Researchers from all over the world have recently developed an interest in the utilization of waste materials in the concrete industry. Using silica fume (SF) and ground granulated blast furnace slag (S) to manufacture self-compacting mortars (SCMs) could be a step toward sustainable waste management and produce the unique fresh qualities needed for SCMs. This research evaluates the abrasion and high-temperature resistance of SF and S based SCMs. A total of 14 mixtures were designed by partially replacing SF and S with Portland cement (PC) including control, binary and ternary mixtures. Binary mixtures were obtained by replacing cement by SF and S at replacement rates of 5, 10, 15 and 20 % and 10, 20, 30 % by weight respectively. Ternary mixtures were determined at the rates of 5, 10, 15 and 20 % SF and 10 and 20 % S respectively. The flexural strength and compressive strength of SF and S based binary and ternary water curing SCMs samples were determined at the age of 7, 28 and 90 days at room conditions. SCMs specimens were exposed to high temperatures after 90-day water curing. Water absorption, apparent porosity, sorptivity and abrasion resistance of 28-day water cured SCMs samples was also determined. The fresh and rheological properties of SCMs was evaluated by conducting mini-slump flow and viscosity tests. Cost analysis of the SCMs were also performed. The experimental results exhibited that the flowability of SCMs mixes containing SF was reduced with the increasing rate of SF compared to control while the workability of S incorporated SCMs mixes increased with the increase of S in comparison to control mixtures. Late- age of compressive strength above 70 MPa was achieved for 20 % SF incorporated binary mixture and 15 %SF and 10 % S incorporated ternary mixture. The ternary mixture with 15 % SF and 10 % S also exhibited the best abrasion resistance and the lowest sorptivity. Overall, it can be concluded from the mechanical characteristics and abrasion resistance that ternary combination of S with SF content of especially above 10 % and can be used to manufacture self-compacting mortar with a smaller carbon footprint.
AtıfScopus60WoS56OpenAlex62
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MakaleYalnız künye2022Scopus SJRQ1/r/munzur/2503
Cooling of non-sloped, positively sloped, and negatively sloped arrangements of Li-ion batteries with a phase change material connected to a solar system
Akkurt, Nevzat; Aghakhani, S.; Mahmoud, Mustafa Z.; Abdelrahman, Anas
Three cylindrical Li-ion batteries are simulated using COMSOL Multiphysics in this study. A circular PCM layer is used to cover the batteries. A battery pack connected to a solar system is tested to store energy in a residential building. The PCM is 100% melted at the beginning, and the frozen PCM volume fraction (PVOF) is studied over time. In addition, the temperatures of individual batteries in three different configurations are analyzed at air velocities 1 and 3 mm/s. The three battery configurations included a positive slope, a negative slope, and no slope. The finite element method (FEM) is utilized to derive algebraic equations. The test results are given to the network as training data, and different neural network architectures are tested in terms of the number of layers and the number of neurons in each layer, and finally a structure that has a minimum mean squared error as a network. Battery behavior predictor is selected. Finally, this model is given to the optimization algorithm as an optimization function to investigate the point at which the maximum voltage is obtained. The results showed that the positively sloped battery configuration decreased the temperatures of the batteries, while the non-sloped configuration increased the temperatures. In addition, the positively sloped configuration resulted in more frozen PCM than non-sloped and negatively sloped configurations at a given time. The minimum frozen PCM was observed in the non-sloped configuration. A change in the air velocity from 1 to 3 mm/s increased the frozen PCM and improved the cooling of the batteries.
AtıfScopus15OpenAlex13
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MakaleYayıncıda açık erişim2022Scopus SJRQ1/r/munzur/2501
Self healing of alkali active mortars with expanded perlite aggregate
Yılmazer Polat, Berivan
The use of alkali-activated mortars instead of cemented mortars provides an advantage in terms of various properties such as high strength, fast curing, and high durability by terminating cement production. However, concrete cracks reduce durability and strength, thus, it is crucial that they be healed. This study aimed to investigate the healing of early microcracks in geopolymer mortars by using Sporasarcina pasteurii, which makes carbonate precipitation, and expanded perlite aggregate as the bacteria carrier. This is the first study to investigate the bacterial healing of an alkali-activated geopolymer mortar using expanded perlite aggregate without applying a complex encapsulation process to the bacterial agents. For this purpose, optical, physical, and mechanical changes caused by self-healing were observed ahead of and after the cure period with tests like water absorption, compressive strength, UPV, SEM, FTIR, and optical microscope images. The results showed that bacterial cells could sporulate directly on the expanded perlite aggregate, visually improving the crack closure rate of the samples by a majority to 100 %, and the unit weights of all samples healed in DM and containing bacteria increased by up to 5 %.
AtıfScopus33WoS31OpenAlex28
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MakaleAçık Erişim2022Scopus SJRQ1/r/munzur/2496
Experimental study on heat transfer properties of gravity heat pipes in single/hybrid nanofluids and inclination angles
Wang, Zhaoxiao; Zhang, Hui; Yin, Lei; Yang, Di; Yang, Gang; Akkurt, Nevzat; Liu, Dinghai; Zhu, Lidong; Qiang, Yujie; Yu, Fan
In order to meet the working requirements of heat pipes under complex working conditions and high heat flux density, and propose corresponding thermal management solutions. In this paper, the single and hybrid nanofluids (TiO2-H2O, Al2O3-H2O, Al2O3+TiO2-H2O) with mass fraction of 5% under the gradient of gravity heat pipe at 50°, 60°, 70°, 80°, 90° are studied. The changes in thermal resistance, thermal efficiency and equivalent heat transfer coefficient of water were compared with deionized water. The results are as follows: The overall efficiency of gravity heat pipe ranges from 70% to 85%. Compared with deionized water, the nanofluid can effectively improve the heat transfer. At different inclination angles, the hybrid nanofluid with the same mass fraction shows the reverse trend compared with the single nanofluid by decreasing the thermal resistance of the heat pipe and increasing the heat transfer efficiency. At an inclination angle of 70°, the heat transfer efficiency of the nanofluid Al2O3+TiO2-H2O is 6.8% weaker compared to TiO2-H2O and 4.5% weaker compared to Al2O3-H2O. At a tilt angle of 60°, the heat transfer capacity of Al2O3+TiO2-H2O nanofluid increases by 7.3% compared to TiO2-H2O and by 5.6% compared to Al2O3-H2O.
AtıfScopus47OpenAlex45
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MakaleAçık Erişim2022Scopus SJRQ1/r/munzur/2452
Experimental study on synergistic enhancement of thermal performance of a closed two-phase thermosyphon by a TiO2nanofluid doped with Al2O3
Xu, Qian; Yang, Gang; Jia, Shuhui; Wang, Zhaoxiao; Akkurt, Nevzat; Zhang, Hui; Zhou, Qiang; Shen, Meng; Yang, Di; Zhu, Lidong
The heat transfer performance of two-phase closed thermosyphon solar collectors (TPCTs) can be improved by adding nanoparticles to the conventional working fluid, but it is necessary to ensure good rheological properties while improving the heat transfer performance. Therefore, spherical (TiO2) nanoparticles with good rheological properties and rod-shaped (Al2O3) nanoparticles with high thermal conductivity were mixed and applied to the TPCT. First, the effects of individual factors such as the concentration of nanoparticles and the operating parameters on the thermal performance of the TPCT were investigated and a regression analysis was performed. Then, the joint effect of inclination angle and filling ratio on the thermal performance of TPCT was further investigated by orthogonal experiment. The results show that doping TiO2 with Al2O3 can further improve the thermal performance of TPCT. For the volume concentration of 0.6% of nanoparticles, filling ratio of 50% and inclination angle of 80°, the best heat transfer performance of TPCT was achieved. Compared with the deionized water (DW), the thermal resistance of the single (TiO2-H2O) and hybrid (Al2O3+TiO2-H2O) nanofluid TPCT is reduced by 10.7% and 13.4%, the thermal efficiency is increased by 11.0% and 13.7%, and the equivalent heat transfer coefficient is increased by 16.2% and 18.7%, respectively.
AtıfScopus38OpenAlex41
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MakaleYalnız künye2022Scopus SJRQ1/r/munzur/2422
The influence of battery distance on a hybrid air-cooled cylindrical lithium-ion battery phase change material thermal management system for storing solar energy
Akkurt, Nevzat; Aghakhani, S.; Mahmoud, Mustafa Z.; Tag El Din, ElSayed M.
The cooling of a lithium-ion battery pack made up of three cylindrical batteries in a channel is studied using the finite element technique in this research. The phase change material (PCM) is surrounded by a laminar flow of air. The solid PCM fraction values and the average temperature of each battery and battery pack at various periods were studied by varying the distance between the batteries from 7 to 10 mm and adjusting the speed from 0.1 to 0.3 cm/s. When compared to other batteries surrounding this battery, the left battery had the lowest temperature and the maximum quantity of solid PCM was generated at various periods, according to the findings of this article. At 0.1 cm/s, the distance 7 mm is the greatest and the distance 8 mm is the lowest in the left battery, the distance 10 mm is the largest in the center battery, the distance 8 mm is the lowest in the right battery, and the distance 8 mm generates the least amount of solid PCM in the battery pack. The second and third batteries, as well as the battery pack, have the lowest average temperature across various distances of the batteries due to a distance of 10 mm between them. Increasing the speed from 0.1 to 0.3 cm/s causes the temperature to decrease in a time-dependent manner.
AtıfScopus37OpenAlex38
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MakaleAçık Erişim2022Scopus SJRQ1/r/munzur/2414
Numerical investigation the hydrodynamic parameters of the flow in a wavy corrugated channel using different turbulence models
Akbari, Omid Ali; Haghjoo, Hossein; Abed, Azher M.; Karimi, Mahsa; Maghzian, Ali; Shabani, Gholamreza Ahmadi Sheikh; Anvari, Amirmasoud; Akkurt, Nevzat; Toghraie, Davood
In this research, turbulent flow numerical models in a wavy channel were investigated. The studied channel is simulated in two dimensions and symmetrically in the range of Reynolds numbers from Re=10,000 to 80,000. The significant cause of this research is to investigate and determine the appropriate method for estimating the behavior of turbulent flow in a wavy channel. In this research, the behavior of turbulent flow in a wavy channel will be simulated in 7 different ways, which are k-ω SST, k-ϵ RN, k-ϵ Realizable, k−ϵ Standard, k-ω Standard, Reynolds stress and Spalart-Allmaras. The findings of this research show that the impacts of the presence of flow viscosity (friction) and the presence of adverse pressure gradients are factors that strongly affect the velocity profiles in the upstream areas of the corrugated section. Among the studied models, due to better compatibility and guessing of flow and hydrodynamic properties, k-ω SST methods and Reynolds and Spalart-Allmaras stress are introduced as the best methods for such geometries. On the other hand, increasing the accuracy of other turbulence methods is related to the flow physics and geometric structure of each problem. In this research, the hydrodynamic parameters of the flow such as pressure drop, skin friction factor, and dynamic pressure drop coefficient and vortex contours, and pressure are plotted and described.
AtıfScopus7OpenAlex8
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MakaleYalnız künye2022Scopus SJRQ1/r/munzur/2348
Performance evaluation of Turkish Universities by an integrated Bayesian BWM-TOPSIS model
Gul, Muhammet; Yucesan, Melih
This study aims to develop a university ranking model with the aid of performance measures in the “University monitoring and evaluation reports-2019” published by the Council of Higher Education Institution in Turkey. In this context, some of the performance criteria stated in these reports are filtered and 34 sub-criteria under five main criteria are weighted using the Bayesian Best-Worst Method (BBWM). Then, 189 listed public and private universities are ranked using the TOPSIS multicriteria decision-making (MCDM) method. We have adopted the MCDM concept because many evaluation criteria/sub-criteria and alternative universities are taken into account. For this study, we apply an integrated MCDM model. First, we use BBWM to accomplish the first goal and adopt the TOPSIS method for the second purpose, using the BBWM results. Our purpose in using BBWM is due to its probabilistic structure that reduces the loss of information when handling group decisions. In this context, the evaluations of 11 academic experts are combined and a solid weighting is made by obtaining the credal rankings of performance criteria. Using TOPSIS is its logic of proximity to ideal and the ability to evaluate many alternatives. In the context of the study, state-private university-based, nomenclature of territorial units for statistics-2 (NUTS-2)-based and classical geographical regions-based rankings are also discussed. The study seeks to help universities optimize their performance efficiently. The results of the study can be adapted as a reference for other educational institutions and public institutions in their efforts to evaluate, improve their performance and form various policies.
AtıfScopus79WoS61OpenAlex79
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MakaleYalnız künye2021Scopus SJRQ1/r/munzur/3054
Problem- based learning in live online classes: Learning achievement, problem-solving skill, communication skill, and interaction
Aslan, Alper
The purpose of the study is to investigate the effect of first aid training in live online classes using the problem-based learning approach on students' learning achievement, problem-solving skills, communication skill, and interaction. The pre-test and post-test quasi-experimental design with a control group was used in the quantitative dimension of the study. The study group was conducted with forty-five university students. While live online classes in the experimental group were carried out via the PBL approach, live online classes in the control group were traditionally carried out via teacher-based methods without any intervention. Zoom application was used in both groups during live online classes. Group work in the experimental group was conducted using breakout rooms. The process of data collection and the experimental procedure of the study was completed in six weeks. Within the scope of the study, courses took three 40 min periods every week. The Learning Achievement Test, the Perceived Problem-solving Skills Scale, the Communication Skills Scale, and the Online Course Interaction Level Determination Scale were used for data collection tools. The results of study show that students who attended live online classes using PBL had higher levels of learning achievement, problem-solving skills and live online class interaction than students who attended live online classes using teacher-based methods. No significant difference between the communication skills of the groups was observed.
AtıfScopus143WoS76OpenAlex229
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MakaleYalnız künye2021Scopus SJRQ1/r/munzur/3030
Performance of marble powder on cementitious composites including waste steel chips as an additive
Gülmez, Nihan
The reuse of industrial waste materials in cement-based composites contributed to preventing increasing environmental problems and reducing production costs. This article examined the effectiveness of using recycled steel chips (Ast) from metal industry waste and waste marble powder (BMP) instead of cement and the possibility of obtaining eco-efficient specimen. While steel chips included in mortars as additives decreased workability, marble powder increased it. An increment in the level of substitution of steel chips resulted in a subsequent increase in water absorption percentages and apparent porosities of mortars. Maximum flexural strength was obtained in 2% steel chips-10% marble powder in waste system.
AtıfScopus16WoS15OpenAlex21
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MakaleYalnız künye2021Scopus SJRQ1/r/munzur/3003
Relationship of knowledge about and attitudes towards violence with recognition of violence against women among health staff in pre-hospital emergency medical services
Gümüşsoy, Süreyya; Dönmez, Sevgül; Ekşi, Ali; Dal, Nursel Alp
Background: Domestic violence, specifically, violence against women, is prevalent in all segments of society regardless of social class, ethnicity, culture or country. In other words, domestic violence is a global concern. Aim: The study aims to investigate the relationship between the attitude and knowledge of the health staff in pre-hospital emergency medical services about violence against women and their recognition of such form of violence. Methods: This descriptive study was conducted on 1023 paramedics and emergency medicine technicians who work in the pre-hospital emergency health setting and are members of the Paramedic and Pre-hospital Emergency Medicine Association. The Attitudes towards Violence against Women Scale (ATVAWS) and Health Staff's Recognition of Signs of Violence against Women Scale (HPRSVAWS) were used for data collection. Results: The mean scores for the ATVAWS and HPRSVAWS were 46.68 ± 6.92 and 20.31 ± 3.23, respectively. Of the participants, 48.5% had been subjected to violence, 43.93% had been subjected to violence perpetrated by their mothers, 41.53% had been exposed to physical violence and 4.2% remain exposed to domestic violence. Participants who had been exposed and those who remain exposed to domestic violence produced high scores in ATVAWS, which indicates an improvement in the traditional approach (less opposing view) to violence. High scores in the ATVAWS for (a) those who were exposed to violence in their workplaces, (b) who had never attended to actual or suspected cases of violence against women in their professional life, (c) who had attended to seven or more cases of violence against women, (d) who were less competent in physically examining actual or suspected cases of violence and (e) who had not been trained on violence against women, which indicates an increase in the traditional approach to violence. Conclusion: The study found that health staff in emergency health stations better recognised the signs of violence against women as their attitudes towards violence were less similar to the traditional approach. That is, they mostly held non-violent views. The characteristics, attitudes, perceptions and values of health professionals were considered important factors in addressing violence.
AtıfScopus7WoS4OpenAlex10
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MakaleYalnız künye2021Scopus SJRQ1/r/munzur/2995
Crack failure in hydrodynamically lubricated bearings: A case study hydraulic turbine
Taşgın, Yahya; Kahraman, Gökhan
This study investigates the trunnion crack of a 50 MW hydraulic turbine in the generator guide bearing. The crack area has been examined metallographically and the fixing method for the the trunnion crack has been explained. Result of the study shows that the reason for the formation of the bearing trunnion crack can be the thermal stresses that occur during the mounting of the bearing trunnion to the turbine shaft and the material fatigue that occurs during the operation of the hydraulic turbine.
AtıfScopus9WoS7OpenAlex9
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MakaleAçık Erişim2021Scopus SJRQ1/r/munzur/2982
Influences of sample shape, voltage gradient, and electrode surface form on the exergoeconomic performance characteristics of ohmic thawing of frozen minced beef
Çokgezme, Ömer Faruk; Döner, Deniz; Çevik, Mutlu; Kemahlıoğlu, Ali Varsın; İçier, Filiz
In the present study, it was aimed to investigate the exergoeconomic performance of ohmic thawing (OT) system during the thawing of frozen minced meat (lean beef). The effects of the sample shape (X: 13 × 4 × 3 cm, Y: 13 × 6 × 2 cm, Z: cylinder with a height of 13 cm and diameter of 3.91 cm), electrode surface form (titanium foil with smooth surface, titanium electrode with needle-type surface and titanium electrode with pyramid-type surface), and voltage gradients (10, 13, and 16 V/cm) were investigated. Lower exergoeconomic values were obtained for the cylindrical shape compared to the rectangular prism. The lowest exergy efficiency value (12.45 ± 0.42), is was obtained for the cylindrical shape at 10 V/cm voltage gradient with titanium foil electrode. The needle-type surface electrodes had higher performance values than other electrodes. The exergoeconomic performance increased as the voltage gradient increased. The lowest unit exergy cost (72.40 ± 2.8) was obtained for rectangular prism shape at 16 V/cm with needle-type electrode. The comprehensive exergoeconomic evaluation in this study exhibited the energy utilization effectiveness and unit exergy cost of OT.
AtıfScopus32WoS28OpenAlex30
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MakaleAçık Erişim2021Scopus SJRQ3/r/munzur/2962
Preliminary investigation on chemical composition and bioactivity of differently obtained extracts from Symphytum aintabicum Hub.- Mor. &Wickens
Zengin, Gokhan; Sinan, Kouadio Ibrahim; Ak, Gunes; Angeloni, Simone; Maggi, Filippo; Caprioli, Giovanni; Kaplan, Alevcan; Çakılcıoğlu, Uğur; Akan, Hasan; Jugreet, Sharmeen
Symphytum species, commonly known as comfrey, hold a long history of folk medicinal uses for healing wounds, bone fractures and other pain resulting from inflammation. However, many species belonging to this genus have not yet been scientifically investigated and hence investigation in this regard is warranted. In the present research, S. aintabicum extracts prepared by different extraction techniques (homogenizer assisted extraction, infusion and maceration) were assayed for their chemosystematic attributes (total phenolic, flavonoid) as well as bioactive compound contents, antioxidant and enzyme inhibition potentials. For instance, the extracts were found to possess phenolic and flavonoid levels ranging from 35.50 to 112.25 mg GAE/g and 2.54–25.12 mg RE/g, respectively. In general, the extracts displayed significant antioxidant activity. However, methanolic and infusion extracts were observed as the most potent radical scavengers and reducing agents, most likely related to their phenolic content. The extracts also showed metal chelating power and total antioxidant capacity in phosphomolybdenum assay. Moreover, while all extracts showed inhibition on amylase, only the methanolic extracts acted as inhibitors of cholinesterases and tyrosinase, most probably due to their relatively higher flavonoid content. The findings also indicated that the extraction method as well as the solvent type used to more or less affect the yield of the bioactive compounds and extracts’ bioactivity reported herein. Hence, as a first report highlighting the in vitro pharmacological properties of S. aintabicum, promising results were revealed from the quantitative chemosystematic analysis of bioactive components present and as sources of antioxidants and enzyme inhibitors against key human illnesses, thus providing scope for potential applications in phytomedicine development.
AtıfScopus15OpenAlex14
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MakaleAçık Erişim2021Scopus SJRQ1/r/munzur/2905
Thermoset powder coating wastes as filler in LDPE – Characterization of mechanical, thermal and morphological properties
Kismet, Yilmaz; Dogan, Akar; Wagner, Manfred H.
In this study, three different electrostatic powder coating wastes of thermoset structure were used as fillers for low-density polyethylene (LDPE). The mechanical, thermal, and morphological properties of these composites materials are reported. The thermoset powder coating wastes were hydrolyzed using water and alcohol, and then 10%, 20%, and 30% by weight of the deactivated wastes were mixed with LDPE, first in a mechanical dry mixer, and subsequently homogenized by melt compounding in an extruder at about 160 °C. Standard tensile test bars and plate-shaped samples were produced from these homogeneous compounds by injection molding. The effects of adding hydrolyzed powder coating wastes on the properties of LDPE were determined by mechanical, thermal, and morphological tests. Tensile strength and perforation threshold of the sample filled with powder coating wastes decreased to some extent compared to un-filled sample. However, an increase in izod impact and bending strengths has been observed. The results of this investigation demonstrate that powder coating wastes with thermoset structure can be used as fillers in LDPE.
AtıfScopus13WoS15OpenAlex16
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MakaleYalnız künye2021Scopus SJRQ3/r/munzur/2898
Enzyme inhibition and antioxidant functionality of eleven Inula species based on chemical components and chemometric insights
Ceylan, Ramazan; Zengin, Gokhan; Mahomoodally, Mohamad Fawzi; Sinan, Kouadio Ibrahime; Ak, Gunes; Jugreet, Sharmeen; Cakır, Oguz; Ouelbani, Rayene; Paksoy, Mehmet Yavuz; Yılmaz, Mustafa Abdullah
The members of the genus Inula have been widely used in traditional medicinal. In the present study, 11 Inula species were investigated for their phytochemical composition, antioxidant and enzyme inhibitory effects. While quinic acid was the principal compound in I. anatolica, I. britannica, I. inuloides, I. oculus-christi, I. peacockiana, I. sechmenii, I. thapsoides and I. viscidula extracts (22.43–42.02 mg/g dry extract (DE)), I. aucheriana and I. discoidea extracts contained rutin as their most abundant compound (23.28 and 79.10 mg/g extract, respectively). Interestingly, all the Inula extracts were active inhibitors of the five key clinical enzymes (acetylcholinesterase (3.56–5.13 mg galantamine equivalent (GALAE)/g), butyrylcholinesterase (1.49–7.34 mg GALAE/g), tyrosinase (112.31–122.13 mg kojic acid equivalent (KAE)/g), α-glucosidase (0.77–2.08 mmol acarbose equivalent (ACAE)/g) and α-amylase (0.73–0.90 mmol ACAE/g)). Furthermore, the extracts were observed to exhibit substantial antioxidant capacity (1,1-diphenyl-2-picrylhydrazyl (DPPH): 58.99–188.22 mg trolox equivalent (TE)/g); 2,2-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) (ABTS): 90.51–220.97 mg TE/g; cupric reducing antioxidant capacity (CUPRAC): 169.88–460.53 mg TE/g; ferric reducing antioxidant power (FRAP): 81.57–237.99 mg TE/g; metal chelating activity: 8.31–25.39 mg ethylenediamine tetraacetate equivalent (EDTAE)/g; phosphomolybdenum: 1.55–2.49 mmol TE/g). In conclusion, the Inula species studied herein showed promising pharmacological potentials justified by the presence of a panoply of bioactive compounds.
AtıfScopus60OpenAlex60
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MakaleAçık Erişim2021Scopus SJRQ2/r/munzur/2889
Evaluation of chemical constituents and biological properties of two endemic Verbascum species
Zengin, Gokhan; Mahomoodally, Mohamad Fawzi; Sinan, Kouadio Ibrahime; Sadeer, Nabeelah; Maggi, Filippo; Caprioli, Giovanni; Angeloni, Simone; Mollica, Adriano; Stefanucci, Azzurra; Ak, Gunes
Members from the Verbascum genus are well appraised for their traditional uses against a variety of ailments including anti-inflammatory related disorders. This study thus attempts at validating the biological properties of two underexplored Verbascum members namely Verbascum euphraticum Benth. (V. euphraticum) and Verbascum oocarpum Murb. (V. oocarpum) in terms of their antioxidant and enzymatic inhibitory activities. Concentration of specific bioactive compounds was also established and molecular dynamic analysis were conducted on amassed data. Results showed that total phenolic and total flavonoid contents were higher for the methanolic extract of V. oocarpum compared to the methanolic extract of V. euphraticum. Phytochemical quantification revealed that the extraction solvents influenced the phytochemical composition of the extracts. Derivatives of phenolic acids such as 3-caffeoylquinic acid and 3,5-dicaffeoylquinic acid together with some phenolic acids i.e., gallic, vanillic, caffeic, syringic, p-coumaric and ferulic acid, have been detected in the extracts of both Verbascum species. Methanolic extracts of V. euphraticum and V. oocarpum yielded the highest total content of monitored compounds resulting in 162.758 and 3716.861 μg/g of dried weight extract, respectively. The methanolic extracts of both plants showed highest antioxidant potential while the ethyl acetate and hexane extracts were potent inhibitors of cholinesterase, α-amylase and α-glucosidase. Molecular dynamic results indicated that vanillic acid is able to make strong interactions with copper ions of tyrosinase, resulting into an effective anti-tyrosinase activity. In light of the above, both Verbascum species could be considered for future phytopharmaceutical development.
AtıfScopus36OpenAlex36
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MakaleYalnız künye2021Scopus SJRQ1/r/munzur/2864
Sustainable supplier evaluation and transportation planning in multi-level supply chain networks using multi-attribute- and multi-objective decision making
Lo, Huai-Wei; Liaw, Ching-Fang; Gul, Muhammet; Lin, Kuan-Yu
Supplier selection and transportation planning are essential tasks in managing supply chain networks (SCNs). The choice of a supplier has a significant influence on the transportation planning of SCNs, as the transportation routes will change. A limited number of studies in the literature have addressed the supplier selection and transportation planning issues simultaneously. This study proposes a two-stage multi-criteria decision-making (MCDM) approach for sustainable supplier evaluation and transportation planning in multi-level SCNs. Initially, a supplier evaluation framework is proposed using the modified indifference threshold-based attribute ratio analysis (ITARA) and the performance calculation technique of the integrated multiple multi-attribute decision-making (PCIM-MADM) to determine the supplier's performance index. Subsequently, a multi-level SCN model is established, and the sustainable supplier selection and transportation planning problem is solved by the fuzzy multi-objective linear programming (FMOLP) method. A set of real-world data provided by a smart audio manufacturing company has been used to demonstrate the proposed approach. Decision-makers understand the importance of criteria through the weights constructed by the modified ITARA. Moreover, the results of the PCIM-MADM can effectively determine the supplier's ranking and provide improving strategies for underperforming suppliers. The augmented max–min technique of the FMOLP can produce a single optimal solution of the transportation allocation. The results show that our approach can effectively evaluate sustainable supplier performance and optimize transportation planning in SCNs.
AtıfScopus67WoS56OpenAlex64
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MakaleAçık Erişim2021Scopus SJRQ1/r/munzur/2771
Investigation on the properties of new palm-oil-based polyurethane modified bitumen
Vural Kök, Baha; Aydoğmuş, Ercan; Yilmaz, Mehmet; Akpolat, Mustafa
Polyurethane-derived polymer synthesized by the reaction of 4.4′-diphenylmethane diisocyanate (MDI) with the new modified palm-oil-based polyol was used as an alternative additive to thermoplastic-elastomers, such as styrene–butadienestyrene (SBS), the most commonly used additive. The study aimed to investigate the effect of polyurethane (PU) modification on the rheological and chemical structure of base bitumen. The softening point, rotational viscosity, dynamic shear rheometer (DSR), multi-stress creep recovery (MSCR), bending beam rheometer (BBR), and Fourier transform infrared (FTIR) tests were conducted on the binders. The effects of curing time and temperature, isocyanate/hydroxyl (NCO/OH) molar ratio, and PU content were examined and the best modification conditions were determined. It was found that 24 h curing conditions at 85 °C were sufficient for the formation of PU bonds and these processes increased the rutting parameter of the binder by 256% compared to 1 h curing. At 50 °C and a frequency of 5 Hz, the binder with a 4:1 NCO/OH ratio had 63% more complex modulus than the binder with a 10:1 NCO/OH ratio. The 7 wt% PU modified binder had the same performance level as 4% SBS modification and 10 wt% PU modified binder was one degree higher. Moreover, above 60 °C, all the PU modified binders gave lower phase angles compared to the 4% SBS modified binder. 7 wt% PU modified binder showed similar elastic properties against cracks at low temperatures compared to the 4% SBS modified binder. The use of palm oil in the synthesis of PU presents an environmentally friendly and cost-effective solution compared to the use of petrochemical derivatives.
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