Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Dertli, Enes(114)
- Kaya, Yunus(48)
- Şahin, Engin(48)
- İspirli, Hümeyra(47)
- Özen, Soner(38)
- Şenay, Volkan(37)
- Pat, Suat(36)
- Kutlu, Naciye(32)
- Artar, Musa(31)
- Can, Zehra(31)
- Korkmaz, Şadan(31)
- Yilmaz, Mustafa Tahsin(31)
- Öner, Erdal(31)
- Bayram, Sinan(30)
- Cuce, Erdem(30)
- Ertugrul, Mehmet(29)
- Hasar, Ugur Cem(29)
- Ecem Bayram, Nesrin(28)
- Mercan, Emin(28)
- Ayata, Ümit(27)
- Bayraktar, Bülent(27)
- Çolak, Murat(23)
- Özdemir, Akın(23)
- Ayazoglu, Rabil(22)
- Cuce, Pinar Mert(22)
- Sert, Durmuş(22)
- Bayram, Ozkan(21)
- Kamiloğlu, Aybike(21)
- Dirican, Ebubekir(20)
- Kadakal, Mahir(20)
- Abdioglu, Murat(19)
- Birinci, Ahmet(19)
- Tozlu, Alperen(19)
- Gerçek, Yusuf Can(18)
- Taylan, Osman(18)
- Cinar, Mehmet(17)
- Gul, Volkan(16)
- Hasar, Ugur C.(16)
- Kadakal, Huriye(16)
- Kara, Yakup(16)
Yayınlar
- MakaleYalnız künye2023Scopus SJRQ2Cr-substituted nanocrystalline Ni–Co ferrites: tuning dielectric, magnetic, structural, X-band microwave absorption, and characteristic properties
Teber, Ahmet; Sarac, Mehmet F.
The structural, characteristic, dielectric, and magnetic features of Co0.5Ni0.5CrxFe2 − xO4 (0.0 ≤ x≤ 1.0 with a step of 0.2 x-concentration) nanoparticles are prepared via the hydrothermal method. The investigation of characteristics, structural, and magnetic features of the produced nanoparticles are examined through XRD, FT-IR, SEM–EDS, TEM-SAED, and VSM, respectively. AC conductivity and the dielectric investigations are also reported. According to the XRD measurements, all samples have the M-type hexagonal crystal structure nanocrystallites of between 27 and 97 nm. Refined structural parameters using Rietveld analysis are carried out using the TOPAS refinement program. A good match was observed between the diffraction patterns obtained and calculated by Rietveld analysis. Moreover, the morphological analyses indicate that the relatively small spherical structures of Ni–Co ferrites particles can be seen to change from spherical to relatively oval-shaped with increasing chromium content. The results of the FT-IR study show that the spinel structure has formed as predicted because the expected range of absorption bands is present. According to magnetic measurements, Cr-substituted Ni–Co ferrite nanostructures reveal a relatively soft ferromagnetic property. The coercive field (Hc) variation has a propensity to decrease in relation to the Cr-concentration. The electromagnetic constitutive parameters are calculated from measured S-parameters (S11 and S21) using network analyzer and the return losses of the samples are then obtained to determine microwave absorption properties. According to the dielectric and magnetic tangent losses or dissipation factors, both dielectric and magnetic features can mutually reinforce in terms of microwave absorption properties in the X-band. The Cr2O3 impurity peaks obtained by XRD analysis have an effect on the microwave absorption properties. The results of the microwave absorption based on each concentration reveal that there exist electromagnetic wave absorptions between approximately 11 GHz and 12.4 GHz in the X-band. The absorption trend is also towards the Ku-band.
AtıfScopus3WoS3OpenAlex3
İncele - MakaleYalnız künye2023Scopus SJRQ2Socioeconomic status and wellbeing as predictors of students' academic achievement: Evidence from a developing country
Erdem, Cahit; Kaya, Metin
The COVID-19 pandemic has deepened the effects of socioeconomic status (SES) and wellbeing (WB) on students' academic achievement, particularly in developing countries; thus, it becomes necessary to understand the nature of these concurrent relationships. This study aimed to explore the relationships between SES, WB and academic achievement, based on the data from the Programme for International Student Assessment (PISA) in 2018 within the Turkish context. In this cross-sectional study, we used hierarchical multiple linear regression analysis to explore how the independent variables predicted academic achievement in blocks based on data from 6890 students attending 186 schools. The study revealed that the model, including the independent variables, predicted students' achievement in reading, mathematics and science; however, the prediction level of demographic factors and domains of WB were very low, while SES had the highest prediction level. The results offer insights into the predictors of academic achievement and educational inequalities in the context of a developing country.
AtıfScopus35WoS28OpenAlex39İncele - MakaleYayıncıda açık erişim2023Scopus SJRQ1Designing New Model-Based Adaptive Sliding Mode Controllers for Trajectory Tracking Control of an Unmanned Ground Vehicle
Sekban, Hayriye Tugba; Basci, Abdullah
This paper proposes three new dynamic model-based adaptive sliding mode controllers (ASMC) for trajectory tracking control of unmanned ground vehicles (UGV). The controllers combine kinematic and dynamic control to achieve asymptotic stability and finite-time convergence and their stability is verified using the Lyapunov stability theory. The controllers are designed to address the challenges posed by uncertainties in vehicle dynamic parameters and outperform the sliding mode control (SMC) method in trajectory tracking control. The simulation results of the proposed controllers are also discussed in terms of performance metrics. The simulation results show that the controller proposed in rule 1 shows the better performance in terms of trajectory tracking, and then the controllers proposed in rules 2 and 3 have good performances, respectively. In addition, when the simulation results are compared, it is seen that the performance of all three proposed controllers is better than the SMC.
AtıfScopus12WoS10OpenAlex13İncele - MakaleYalnız künye2023Scopus SJRQ3An Investigation on the Behavior of 3D Steel Frames Under Progressive Collapse Effect Using Nonlinear Dynamic Analysis
Tayfur, Bilal; Daloǧlu, Ayșe T.
In this study, the nonlinear dynamic analysis of steel structures against progressive collapse was examined, and the adequacy and validity of the analysis duration defined in the regulation were investigated. In addition, the effects of the seismic resistance and design against progressive collapse constraints on the structure were investigated. An optimization algorithm was used in order to conduct the iterative process with appropriate sections. The frames were analyzed to perform one cycle as recommended in the UFC, and then the analysis duration was extended until at least five cycles had been completed. When the UFC was considered only, it was observed that while some of the designs were classified as safe within the duration specified in the UFC, the structural integrity was seen to get into danger in the subsequent cycles. When constraints related to seismic effect are also included in the process, it was seen that the threat disappeared for the frames examined. In addition, it was observed that the steel frame resisted progressive collapse scenarios by creating formations like Vierendeel beams.
AtıfScopus1WoS1OpenAlex2İncele - MakaleAçık Erişim2023Scopus SJRQ2Characterisation of dextran AP-27 produced by bee pollen isolate Lactobacillus kunkeei AP-27
Yilmaz, Mustafa T.; İspirli, Hümeyra; Alidrisi, Hassan; Taylan, Osman; Dertli, Enes
An exopolysaccharide (EPS) produced by bee pollen isolate Lactobacillus kunkeei AP-27 was characterised in this study. EPS monomeric composition of strain AP-27 was characterised by High-performance liquid chromatography (HPLC) analysis and glucose was the only sugar in the EPS repeating unit. Structural analysis of glucan AP27 by 1H and 13C Nuclear magnetic resonance (NMR) analysis demonstrated that this glucan was a dextran ((1→6)-linked α-D-glucose units as the main body) consisting very low level of (1 → 4)-linked α-D-glucose units (∼ 0.5 %). Dextran AP-27 had a degradation temperature of 308 °C that revealed its superior thermal strength identified by Thermogravimetric (TGA) and Differential scanning calorimetry (DSC) analysis. The molecular weight of dextran AP-27 was determined to be 25 kDa by Gel Permeation Chromatography (GPC) analysis. Crystallographic properties of dextran AP-27 was determined by X-ray diffraction (XRD) analysis that divulged its amorphous feature. Scanning Electron Microscopy (SEM) analysis was applied for microstructural characterisation of dextran AP-27 which revealed its regular sphere like characteristics. These findings suggest that Lactic Acid Bacteria (LAB) strains from different environments such as bee products can be the source for distinct EPS producer strains.
AtıfScopus9WoS8OpenAlex7İncele - MakaleYalnız künye2023Scopus SJRQ3A comparison of the associations between bone turnover markers and different sports fields: combat versus team sports
Yıldız, K.; Uzunçakmak, S. Karabulut; Halıcı, Z.; Özçelik, C.; Yazıcı, A.G.
Sedentary life brings risks that include osteoporosis, while physical activity has many benefits for health in general and the skeletal system. Irisin is a hormone-like myokine regulated by mechanical force and it contributes to cortical and trabecular bone mineral density. This study aimed to investigate the effects of different types of sports on bone health by measuring elite athletes’ fibronectin type III domain 5 (FNDC5), N-terminal collagen type I extension propeptide (PINP), and C-terminal cross-linking telopeptide of type I collagen (CTXI) levels. Combat sports athletes, team sports athletes, and sedentary control subjects were enrolled. Serum levels of proteins were measured by ELISA. FNDC5 levels of elite athletes were higher compared to the sedentary controls (P=0.0014). The highest FNDC5 level was measured in wrestlers among all considered groups. The PINP levels of the athletes were also higher than those of the sedentary control group (P=0.1431). The highest PINP level was determined in boxers. The CTXI levels of the athletes were lower than those of the sedentary control (P<0.0001). The lowest CTXI level was seen in boxers. The FNDC5 and PINP levels of combat sports athletes were higher than those of team sports athletes (P=0.0134 and P=0.0262, respectively), while the CTXI levels of combat sports athletes were lower than those of team sports athletes (P<0.0001). Our results indicated that FNDC5, PINP, and CTXI levels are associated with physical activity. The effect of the exercises performed by athletes of specific sports on bone health has not been studied in much detail before. Combining different exercises for athletes of a particular sport may be more beneficial for bone health.
- MakaleYalnız künye2023Scopus SJRQ2Yttrium-substituted Co0.5Ni0.5YxFe2-xO4 ferrites as microwave absorbers by investigating structural, magnetic, dielectric, and absorption characteristics
Teber, Ahmet; Sarac, Mehmet F.
The effect of Yttrium Substitution on Co0.5Ni0.5YxFe2- xO4 (0.0 ≤ x ≤ 1.0) Ferrites as Microwave Absorbers was investigated to include structural, magnetic, dielectric and X-band absorption properties. The main objective of this work is to enhance microwave absorption properties of materials with interesting dielectric/magnetic behaviors by doping rare earth element of Yttrium based on transition metals. The hydrothermal method was used to create Yttrium (Y) substituted nanoparticles, and the effects of Y-ion substitution on the characteristics, structural, magnetic features were examined by XRD, FT-IR, SEM-EDS, TEM-SAED, and VSM, respectively. Electromagnetic properties were obtained from microwave scattering parameters measured via a metal-backed transmission line and Nicholson-Ross Weir techniques using a vector network analyzer (VNA) in conjunction with an X-band waveguide set. Return loss (RL) values of the samples were obtained from the electromagnetic constitutive parameters (permittivity and permeability). According to the XRD measurements, hexagonal crystal structure of ferrite and YFeO3 as secondary phase nanocrystal sizes are between 11 and 67 nm. Refined structural parameters using Rietveld analysis are carried out using the TOPAS refinement program. A good match was observed between the diffraction patterns obtained and calculated by Rietveld analysis. Moreover, the morphological analyses indicate that the relatively small spherical structures of Ni-Co ferrites particles can be seen to change from spherical to hexagonal-shaped with increasing yttrium concentration. The results of the FT-IR study show that the spinel structure has formed as predicted because the expected range of absorption bands is present. According to magnetic measurements, the coercivity (Hc) results show a modest increase in porosity as the Y-content rises. The results revealed that the minimum RL value and bandwidth vary significantly with the amount of Yttrium in the mixture, indicating that the obtained structures will be useful for broadband microwave applications.
AtıfScopus10WoS11OpenAlex12İncele - MakaleYalnız künye2023Scopus SJRQ3Effects of electromagnetic radiation on neurogenesis and gene expression in amniocytes
Uzun, Coşar; Erdal, Nurten; İzci Ay, Özlem; Karakaş, Ümit; Derici Yildırım, Didem; Durukan, Hüseyin; Akdag, Mahmut Berat; Erdal, Mehmet Emin
The aim of the study was to investigate the genetic effects of commonly used radiofrequency on the amniocytes of pregnant women by examining the changes in the expression of genes related to signal transduction and neurogenesis induced by electromagnetic fields of radiofrequencies of 1800 and 2100 MHz by real-time PCR. Upon exposure of the amniocytes to electromagnetic radiation of 2100 MHz at high field strength, the expression levels of genes with important functions in the Wnt signaling pathways as well as neurogenesis-related genes were increased. The findings suggest that radiofrequency at high field strengths can have genotoxic effects during pregnancy.
AtıfScopus1WoS1OpenAlex1İncele - MakaleAçık Erişim2023Scopus SJRQ1Face presentation attack detection performances of facial regions with multi-block LBP features
Günay Yılmaz, Asuman; Turhal, Uğur; Nabiyev, Vasif
Biometric recognition systems are frequently used in daily life although they are vulnerable to attacks. Today, especially the increasing use of face authentication systems has made these systems the target of face presentation attacks (FPA). This has increased the need for sensitive systems detecting the FPAs. Recently surgical masks, frequently used due to the pandemic, directly affect the performance of face recognition systems. Researchers design face recognition systems only from the eye region. This motivated us to evaluate the FPA detection performance of the eye region. Based on this, in cases where the whole face is not visible, the FPA detection performance of other parts of the face has also been examined. Therefore, in this study, FPA detection performances of facial regions of wide face, cropped face, eyes, nose, and mouth was investigated. For this purpose, the facial regions were determined and normalized, and texture features were extracted using powerful texture descriptor local binary patterns (LBP) due to its easy computability and low processing complexity. Multi-block LBP features are used to obtain more detailed texture information. Generally uniform LBP patterns are used for feature extraction in the literature. In this study, the FPA detection performances of both uniform LBP patterns and all LBP patterns were investigated. The size of feature vector is reduced by principal component analysis, and real/fake classification is performed with support vector machines. Experimental results on NUAA, CASIA, REPLAY-ATTACK and OULU-NPU datasets show that the use of all patterns increased the performance of FPA detection.
AtıfScopus18WoS11OpenAlex19
İncele - MakaleAçık Erişim2023Scopus SJRQ3Socio-economic determinants of environmental degradation: Empirical evidence for the Environmental Kuznets Curve
Gültekin, Ömer Faruk; Sayar, Ramazan; Ari, Yllmaz Onur
The aim of the paper is to examine socio-economic determinants of environmental degradation. The empirical study employs quantile regression which enables separate predictions for different levels of the dependent variable to be made. This study investigated 62 countries from low, middle and some high income countries for 1995-2019. The Environmental Kuznets Curve (EKC) is verified for the aforemented countries in analyzing the relationship between economic growth and carbon emissions using quantile regression. The study also revealed that the schooling rate has a pollution-increasing effect. In addition to the reducing effects of trade openness, democracy, and economic freedom variables on environmental degradation, the opposite effect of life expectancy at birth is observed, increasing environmental degradation. In this context, this paper concluded that the EKC hypothesis is not supported. The government should encourage pollution-reducing policies in low and middle income countries.
AtıfScopus4WoS3OpenAlex5İncele - MakaleYalnız künye2023Scopus SJRQ3The determinants of non-family employees' turnover intentions in family firms
Yazici, Omer; Memili, Esra; Patel, Pankaj C.; Ramadani, Veland
While research on the organisational behaviour and HRM (i.e., organisational identification, justice, commitment, and turnover intentions) in family business contexts has been advancing, the empirical investigation of non-family employees’ perceptions is still scarce. Drawing upon family business-influenced literature and organisational identification, justice, and commitment theories, we explore the determinants of non-family employees’ turnover intentions. Specifically, we examine the impact of non-family employees’ family firm identification and perceived justice on family firm commitment, in turn affecting turnover intentions. Furthermore, we examine the moderation effects of perceived family influence on these links. Our findings demonstrate that non-family employees’ family firm identification and perceived justice positively affect their family firm commitment, which in turn lowers turnover intentions. While family firm commitment mediates the relationship between family firm identification and turnover intentions, perceived family influence moderates the mediation effects of family firm commitment between family firm identification and turnover intentions. 2023 Inderscience Enterprises Ltd.
AtıfScopus1İncele - MakaleYalnız künye2023Scopus SJRQ2Design, synthesis, antioxidant and anticholinesterase activities of novel isonicotinic hydrazide-hydrazone derivatives
Aslanhan, Özlem; Kalay, Erbay; Tokalı, Feyzi Sinan; Can, Zehra; Şahin, Engin
The design and synthesis of hydrazone derivatives are increasing in popularity day by day due to the significant biological activities of this scaffold. In the present study, twelve novel isonicotinic hydrazide-hydrazone analogues were synthesized by the condensation reaction of isonicotinic hydrazide with benzaldehyde possessing sulfonate moiety. The structures of the novel compounds have been characterized in detail using spectroscopic techniques. All compounds have shown inhibitory effects against the AChE enzyme at rates ranging from 21.00 to 59.48%. Among them, compound 5 has exhibited the best inhibitory effect of 59.48% against AChE at a concentration of 0.1 mM. Furthermore, to determine how effective the novel compounds are as antioxidants, FRAP and DPPH studies were also carried out. FRAP values in compounds 1–12 were found to range from 26.989–3415.556 µmol FeSO4.7H2O/mg. They also displayed moderate antioxidant potential in the range of SC50=0.03–87.32 mg/mL compared with the control Trolox (SC50 =0.004) in DPPH radical scavenging activities. It was seen that the AChE inhibition percentages of the compounds were in the range of 23.04–58.10% at 0.1 mM concentration. This is the first research on the synthesis, antioxidant and enzyme inhibition properties of these compounds.
AtıfScopus43WoS37OpenAlex44İncele - MakaleAçık Erişim2023Scopus SJRQ2Preparation of Eumelanin-Encapsulated Stereocomplex Polylactide Nano/Microparticles for Degradable Biocompatible UV-Shielding Products
Putri, Oceu Dwi; Petchsuk, Atitsa; Buchatip, Suthawan; Supmak, Wilairat; Kaewsaneha, Chariya; Thananukul, Kamonchanok; Nim, Bunthoeun; Bayram, Sinan; Thumanu, Kanjana; Opaprakasit, Pakorn
The role of eumelanin as a natural pigment in protecting human skin from ultraviolet (UV) light has drawn vast interest in the research and industrial community. Encapsulation of the compound by various shell materials has been extensively studied to optimize and prolong its shielding efficiency from UV penetration through the skin. Polylactide (PLA)-based copolymers have been widely used in the encapsulation of various active compounds due to their biocompatibility and biodegradability that facilitate sustained release of the active compounds. In this work, stereocomplex PLA (sc-PLA) derived from mixtures of poly(D-lactide-caprolactone-D-lactide), P(DLA-b-CL-b-DLA), a triblock copolymer with linear poly(L-lactide), and PLLA are employed to encapsulate eumelanin by an oil-in-water emulsion (O/W) technique. The effect of eumelanin distribution in PLA's enantiomers and ultrasonication on the physicochemical properties, encapsulation efficiency, and release behavior of the nano/microparticles were evaluated. The potential application of the resulting particles for sunscreen products was assessed in terms of UV absorbance and in vitro sun protection factor (SPF). The nano/microparticles show a hollow spherical structure, whose size can be controlled by ultrasonication. The distribution of eumelanin and the ultrasonication process play a key role in the growth of sc-PLA and the crystalline structure of the particles. The highest encapsulation efficiency of 46.6% was achieved for sc-PLA2U particles. The high content of eumelanin and the hollow structure with a large surface area lead to improvement in the UV absorbance and sunscreen performance of the particles, as revealed by the increase in the SPF value from 9.7 to 16.5. The materials show high potential for various applications, especially in cosmetic and pharmaceutical fields, as UV-shielding products.
AtıfScopus3WoS3OpenAlex3İncele - MakaleYayıncıda açık erişim2023Scopus SJRQ4Development of Alkali-Activated Binders from Recycling Regional Tuff and Marble Wastes
Tekin, İlker; Ciza, Baraka; Gökçe, H.S.
The sustainability goals of the developing world have led many industries to recycle their wastes and reduce emitting greenhouse gases. To contribute to these environmental responsibilities, this study has focused on the development of eco-friendly binder materials from regional ground tuff and marble wastes by the activation of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) or slaked lime (Ca(OH)2). The results of this study show that alkali-activated composites experienced expansion, drying shrinkage cracking, leaching, and efflorescence. The compressive strength values of the NaOH and Ca(OH)2-activated pastes reached up to 15 MPa and 9 MPa, respectively. A reduction in NaOH molarity improved the compressive strength, dimensional stability, and durability of tuff-based alkali-activated pastes.
AtıfScopus5OpenAlex3İncele - MakaleAçık Erişim2023Scopus SJRQ1A comprehensive study on structural properties, photon and particle attenuation competence of CoNiFeCr-Ti/Al high entropy alloys (HEAs)
Sakar, Erdem; Guler, Omer; Alım, Bünyamin; Say, Yakup; Dikici, Burak
It is well known that high entropy alloys (HEAs) have a wide range of potential applications as radiation shielding due to their superior properties. The CoNiFeCr-Ti/Al compositions were chosen for their low cost as HEA in this study. The HEAs were successfully produced using the mechanical alloying (MA) method with equimolar CoNiFeCr, CoNiFeCrAl, and CoNiFeCrTi compositions. The production and structural properties of the alloys were investigated in detail. Besides, the photon and particle radiation shielding properties of the HEAs were calculated with the help of Phy-X/PSD, SRIM (10 keV-20 MeV), and ESTAR (10 keV-20 MeV) programs. The photon-matter interaction parameters were calculated in both specific photon energies emitted from 241Am, 133Ba, 109Cd, 60Co, 137Cs, 131I, and 22Na nuclides and a continuous energy range of 15 keV-15 MeV. The characterization of the alloys was investigated by using X-ray diffraction (XRD) and scanning electron microscopes (SEM) attached to an energy dispersive spectroscopy (EDX). It was found that the HEAs have a highly amorphous structure due to the selected production method. The crystal size of the alloys was calculated as 70, 35, and 20 nm for CoNiFeCr, CoNiFeCrAl, and CoNiFeCrTi, respectively. In terms of shielding properties, it has been determined that the produced HEAs have better shielding characteristics for photon and particle radiations than standard shielding concretes. In addition, the results demonstrated that CoNiFeCr alloy, which has the best shielding ability among the HEA alloys, can be used as a shielding material application requiring photon, electron, proton, alpha, and neutron radiations.
AtıfScopus30WoS32OpenAlex32İncele - MakaleAçık Erişim2023Scopus SJRQ3Isolation and characterization of yogurt starter cultures from traditional yogurts and growth kinetics of selected cultures under lab-scale fermentation
Kayacan Çakmakoğlu, Selma; Vurmaz, Melike; Bezirci, Emine; Kaya, Yasemin; Dikmen, Hilal; Göktaş, Hamza; Demirbaş, Fatmanur; Encu, Betül; Acar Soykut, Esra; Alemdar, Filiz
The development of new starter cultures is a crucial task for the food industry to meet technological requirements and traditional products are important reservoirs for new starter cultures. In this respect, this study aimed to isolate, identify, and determine the technological characteristics of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus strains originated from traditional yogurt samples. Genotypic discrimination of 200 isolates revealed the presence of distinct 19 S. thermophilus and 11 Lb. delbrueckii subsp. bulgaricus strains as potential starter cultures. Strain-specific properties determined the acidification capacity of the yogurt starter cultures and a higher acidification capacity was observed for S. thermophilus strains compared to Lb. delbrueckii subsp. bulgaricus strains. Proteolytic activity was found between 0.012–0.172 and 0.078–0.406 for S. thermophilus and Lb. delbrueckii subsp. bulgaricus strains, respectively. 4 of S. thermophilus and 3 of Lb. delbrueckii subsp. bulgaricus strains were found resistant to all tested bacteriophages. The antibiotic susceptibility tests of the isolates revealed that a very low antibiotic resistance was observed for the yogurt starter cultures. Finally, the growth kinetics of selected strains were determined and the maximum specific growth rate of selected S. thermophilus and Lb. delbrueckii subsp. bulgaricus was calculated as 0.527 h−1 and 0.589 h−1, respectively.
AtıfScopus8WoS10OpenAlex11İncele - MakaleAçık Erişim2023Scopus SJRQ2Determination of toxicity and radioprotective properties of bacterial and fungal eumelanin pigments
Bayram, Sinan; Aygün, Bünyamin; Karadayi, Mehmet; Alaylar, Burak; Güllüce, Medine; Karabulut, Abdulhalik
Purpose: Determination of the protective property of melanin, an organic polymer class consisting of phenolic and/or indolic compounds isolated from bacteria and fungi, against fast neutron radiation. To show that these melanin samples, which also have antioxidant and metal chelating properties, can be used as an active ingredient for a drug to be developed against neutrons used in nuclear research and medicine. Materials and methods: Bacterial and fungal media were prepared, and melanin pigments were produced and isolated. For molecular characterization of pigments, bacterial genomic DNA extraction, 16S rDNA gene amplification processes, and fungal genomic DNA extraction, ITS1, and ITS4 Gene Regions amplification were performed. The DEL assay was implemented to determine the genotoxicity properties of bacterial and fungal melanin pigments. Samples were prepared in a pad measuring 10 ml volume (60 × 15 mm) at a concentration of 0.2–1 microgram in 1% agarose gel for radiation-absorbed dose measurements. Absorption measurements were made using 241Am-Be fast neutron source and Canberra brand NP series BF3 gaseous detector to determine the neutron radiation absorption capacity of all samples. The results obtained to determine the absorption degrees of melanin samples were compared with paraffin and normal concrete, which are widely used in neutron radiation shielding studies. Results: Melanin pigments were obtained using different bacteria and fungi strains. Afterwards, the fast neutron radiation absorption capacity of these purified pigments were determined. Compared to reference samples, these pigments were found to have slightly lower radiation absorbing ability. In addition to these experiments, cytotoxicity tests were carried out using the Yeast DEL assay technique to evaluate the potential for use of these organic pigments in fields such as medicine and pharmacology. According to the results obtained from the tests, it was determined that these melanin samples did not have any toxic effects. Conclusion: It was determined that these melanin samples have the potential to be used as a radioprotective drug active substance to protect the tissues and cells of people exposed to neutron radiation after a nuclear accident or nuclear war. Giving a drug that will be developed by using these active ingredients before or after people are exposed to a radiation environment can provide great benefits.
AtıfScopus12WoS12OpenAlex17İncele - MakaleAçık Erişim2023Scopus SJRQ3Harmonic trigonometrically convexity
Kadakal, Huriye
In this study, we introduce and study the concept of harmonic trigonometrically convex functions and their some algebric properties. We prove two Hermite-Hadamard type inequalities for the newly introduced class of functions. We also obtain some refinements of the Hermite-Hadamard inequality for functions whose first derivative in absolute value, raised to a certain power which is greater than one, respectively at least one, is harmonic trigonometrically convex.
AtıfScopus10WoS12OpenAlex11İncele - MakaleYalnız künye2023Scopus SJRQ2Effective Damping Coefficient of Fluid Viscous Dampers for Dynamic Response Mitigation of Coupled Frames
Düzgün, Oğuz Akın; Hatipoğlu, Yavuz Selim
Purpose: In this study, the effective damping coefficient of the fluid viscous dampers (FVDs) used for coupling two adjacent multi-story frames was investigated, considering soil-structure interaction (SSI) effects under seismic excitation. Methods: A numerical procedure was employed to obtain the dynamic response of the interconnected frames-soil system. The two-dimensional (2D) finite elements were used for the numerical treatment of the adjacent frames and soil region. Viscous boundary conditions were used as special non-reflecting boundaries on the edges of finite soil region. Five different damping coefficients of FVDs are considered to determine the effective damping coefficient. The effective damping coefficient of FVDs was determined by comparing the results from coupled frames with those of the uncoupled frames. Results: The results showed that the most affecting parameter on the system response was found to be soil type. It was also found that the sufficient damping coefficient of the viscous damper is equal to 1 × 105 N s/m for minimum response. Conclusion: When the effective damping coefficient of the FVDs was provided, the maximum values of the roof displacements, the roof accelerations, and the base shear forces are found to decrease by more than 40%.
AtıfScopus3WoS2OpenAlex4İncele - MakaleAçık Erişim2023Scopus SJRQ2Relationship between middle school students’ metacognition and problem-posing performance: A serial mediation analysis
Ada Yıldız, Kübra; Öztürk, Mesut
This study tests a model that predicts the problem-posing performance of sixth-grade students (independent variable metacognition, mediator variables mathematics and native language course success scores at the end of the year). The research was conducted with the relational model. The results regarding the mediation effect indicated that the mathematics course success scores and the native language course success scores were separately full mediators in the effect metacognition has on problem-posing performance. The results regarding serial mediation effect revealed that the mathematics course success scores and native language course success scores had a full mediating effect on the effect of metacognition on problem-posing performance.
AtıfScopus3OpenAlex2İncele