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Koleksiyondaki öğeler
- MakaleAçık Erişim2024Scopus SJRQ1Physicochemical and structural characterisation of a branched dextran type exopolysaccharide (EPS) from Weissella confusa S6 isolated from fermented sausage (Sucuk)
Özpınar, Fatma Beyza; İspirli, Hümeyra; Kayacan, Selma; Korkmaz, Kader; Dere, Sevda; Sagdic, Osman; Alkay, Zuhal; Tunçil, Yunus Emre; Ayyash, Mutamed; Dertli, Enes
Exopolysaccharide (EPS) producing Lactic Acid Bacteria (LAB) species can be presented in distinct environments. In this study, Turkish fermented sausage (sucuk) was tested for the presence of EPS producer LAB strains and slimy-mucoid colonies were selected for further tests. Among the isolates, Weissella confusa strain S6 was identified and tested for the physicochemical characterisation of its EPS. This strain was found to produce 0.74 g L−1 of EPS in modified BHI medium conditions. Structural characterisation of EPS S6 by 1H and 13C NMR demonstrated that EPS S6 was a highly branched dextran type glucan formed by mainly (1 → 2)-linked α-D-glucose units together with low levels of (1 → 3)-linked α-D-glucose units as branching points. This structure was further confirmed by methylation analysis detected by GC–MS. An average molecular weight of 8 × 106 Da was detected for dextran S6. The FTIR analysis supported the dextran structure and revealed the presence of distinct functional groups within dextran S6 structure. A strong thermal profile was observed for dextran S6 detected by DSC and TGA analysis and dextran S6 revealed a degradation temperature of 289 °C. In terms of physical status, dextran S6 showed amorphous nature detected by XRD analysis. SEM analysis of dextran S6 demonstrated its rough, compact and porous morphology whereas AFM analysis of dextran S6 detected in its water solution showed the irregularity with no clear cross-link within the dextran chains. These technological features of dextran S6 suggests its potential to be used for in situ or ex situ application during meat fermentations.
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İncele - MakaleYalnız künye2024Scopus SJRQ2Middle School Fifth-Grade Students’ Level of Understanding the Concept of Condensation in Different Contexts
Cengiz, Ekrem; Arıcı, Faruk
Evaporation, condensation, and boiling are fundamental concepts taught in science and chemistry classes, closely linked to daily life. These concepts are vital for students to grasp the transformation and conservation of matter, the particulate nature of matter, and related principles. This study evaluated fifth-grade students’ comprehension of condensation across various contexts. The research involved 80 male and 59 female students from a public school in a qualitative phenomenological study. Data analysis utilized the content analysis method. As a result of the study, it was revealed that the students who participated in the research did not understand the concept of condensation sufficiently and could not explain this concept at the desired level in different contexts. Based on the findings, incorporating real-life contexts when teaching the concept of condensation can enhance the understanding of the topic. Moreover, it highlights the significance of an investigative approach to learning new concepts.
AtıfScopus1WoS1OpenAlex2İncele - MakaleAçık Erişim2023Scopus SJRQ2A simulation study on colloid diffusion under time-varying optical potentials
Yücel, Harun
With its momentum transfer, light is a primary tool for manipulating microscale objects in various research fields, including physics, chemistry, and biology. Optical force fields, also known as energy landscapes, play a crucial role in manipulating micro- and nano-sized objects, enabling the sorting of mixed micro-sized particles. This study investigates the effect of time-varying periodic optical fields created by a structured light illumination technique on the diffusion motion of micro-sized colloidal particles suspended in a liquid. A simulation code is developed to calculate the optical force acting on particles due to any time-varying optical force field. Simulations are performed to produce trajectories of particles of different sizes suspended in a liquid for different illumination patterns. The results show that the average velocities of the particles depend on the projected optical pattern parameters and that mixtures of particles of different sizes can be separated using time-varying sequential patterns, thereby improving particle separation resolution.
AtıfScopus2WoS2OpenAlex3İncele - MakaleAçık Erişim2024Scopus SJRQ3Analyzing global competitiveness of Turkish air conditioning industry
İzgi, Fatma; Kavacık, Mustafa
The global economy significantly relies on the air conditioning sector, which has been gaining increased importance worldwide and in Türkiye due to the impact of global warming, climate change, and the diminishing energy resources. As a multifaceted industry encompassing air conditioning, heating, installation, insulation, refrigeration and ventilation sector has been adapting to the growing demand for environmentally friendly and energy-efficient solutions. This study analyzes air conditioning industry of Türkiye and its sub-product groups in terms of its ability to compete internationally, spanning from 2001 to 2021. To assess competitiveness, we employed various analytical tools, including Balassa's Revealed Comparative Advantages Index (RCA), Vollrath Indices (RXA, RMP, RTA, RC), Revealed Symmetric Comparative Advantages Index (RSCA), Trade Balance Index (TBI), and Product Mapping method. Notably, there is no research that scrutinize the competitiveness of the Turkish air conditioning industry utilizing the Product Mapping. The study findings emphasize that air conditioning industry of Türkiye has competitiveness. Within the sub-product group, the analysis reveals that Türkiye has competitiveness for 11 products, a near-limit competitiveness for 3 products, and a lack of competitiveness for 10 products.
AtıfScopus4OpenAlex5TR Dizin2
İncele - MakaleYalnız künye2023Scopus SJRQ1Gamma-ray and neutron shielding capability of blended cement-stabilized barite fillers developed by maximum density method
Gökçe, H.S.; Öksüzer, N.; Kamiloğlu, H.A.; Yılmaz, F.
The disposal of radiological wastes in the deep geological repositories has become an important issue for the reduction of hazardous risks on the human and biological environments. In this study, blended cement-stabilized barite fillers against gamma rays and neutrons have been developed with the use of the maximum density method by considering various amounts of water (100–300 kg/m3), binder (4–10%), and compaction energy (500–2000 kJ/m3). According to the experimental series of these filler materials, satisfactory response surface results have been achieved in the study. The experimental results revealed that compacted filling material can ensure an efficient shielding capability for gamma rays and neutrons when designed with a density of 3.064 g/cm3. An increase in binder content, water content, and compaction energy has improved the compressive strength of these materials up to 37 times according to that of the poorest series. Neutron and gamma-ray shielding capabilities were found to be 119 and 14% higher than those of the poorest filler material, respectively when theoretical and experimental results are considered in the study.
AtıfScopus4WoS3OpenAlex5İncele - MakaleAçık Erişim2023The effects of artificial weathering on the pendulum hardness of chestnut wood applied with polyurethane varnish after heat treatment; [Isıl işlem sonrası poliüretan vernik uygulanmış kestane odununda salınımsal sertlik üzerine yapay yaşlandırmanın etkileri]
Ulay, Göksel; Ayata, Ümit
The effects of artificial weathering (576 h) on the pendulum hardness values of Anatolian chestnut (Castanea sativa Mill.) wood applied with polyurethane varnish (PU) after heat treatment at 190°C for 1.5 h and at 212°C for 2 h were investigated. The results revealed that heat treatment, weathering period, and interaction were significant. The hardness values of the heat-treated materials were higher than those of the non-heat-treated test samples. The highest hardness value was determined in the un-weathered group of the test samples that were heat-treated at 190°C for 1.5 h while the lowest value was determined in the group that was heat-treated at 190°C for 1.5 h and weathered for 432 h. The highest reduction rates after weathering were obtained on samples that were heat-treated at 190°C for 1.5 h, followed by heat-treated at 212°C for 2 h and non-heat-treated. It was observed that the heat treatment application caused different pendulum hardness values in chestnut wood samples covered with polyurethane varnish.
AtıfScopus3OpenAlex2İncele - MakaleAçık Erişim2025Scopus SJRQ1The mediating role of optimism between reading habits and meaningful living
Guven, Ahmet Zeki; Banaz, Emrullah; Özbilen, Uğur; Şahin, Tuğrul Gökmen
The present study sought to examine the relations between reading habits, perceived meaningful living, and optimism through structural equation modeling. To this end, we recruited undergraduate students enrolled in the Turkish language teaching program of a state university and collected the data using the Reading Attitude and Habits Scale, the Meaningful Living Scale and the Optimism-Pessimism Questionnaire. More than half (58.4%) of students were females, 52% were aged 21–30 years, and 34.2% were second-year students. The data were analyzed using SPSS 24.0 and SPSS AMOS 20.0. The findings showed a significant relationship between reading habits and meaningful living, with optimism serving as a significant mediator. Model fit indices confirmed the validity of the SEM model (RMSEA = 0.061, CFI = 0.94, TLI = 0.96). We also found that optimism served as a significant mediator in the relation between reading habits and perceived meaningful living. The findings suggest encouraging undergraduate students’ reading habits and designing and offering counseling services to foster students’ optimism and perceived meaningful living. Moreover, further research with diverse demographic groups is needed to elucidate more on the subject.
AtıfScopus1WoS1OpenAlex1İncele - MakaleYalnız künye2024Scopus SJRQ2The wound healing effect and DNA damage repair of exopolysaccharide extracted from Weissella cibaria MED17
Kahraman-Ilıkkan, Özge; Akad Dinçer, Selin; Bağdat, Elif Şeyma; Çağlar, Işılsu; Dertli, Enes; İspirli, Hümeyra; Şahin, Feride İffet
Lactic acid bacteria can synthesize exopolysaccharides (EPSs), and some of these EPSs have pharmaceutical or medicinal properties. However, the wound healing capacities of EPSs have rarely been reported. In this study, EPS extracted from Weissella cibaria MED17 was used to investigate wound healing capacity. MED17 EPS was previously characterized and antioxidant capacity was also demonstrated. The application dose of the compound was determined by the MTT assay. The comet assay was applied to reveal the free radical scavenging activity and protection capacity of MED 17 against DNA damage by inducing oxidative stress and DNA damage with Mitomycin-C (MMC) in the cells. The comet assay showed that 15 mg/ml MED 17 EPS could ameliorate DNA damage by 50%. Moreover, the scratch test investigated the wound-healing effect of MED 17 EPS on HT-29 colon cells. MED 17 EPS could stimulate the migration of HT-29 and ameliorate MMC-induced DNA damage. However, further studies need to be conducted to clarify the mechanisms of the wound-healing process of MED 17.
AtıfScopus5WoS5OpenAlex5İncele - MakaleAçık Erişim2023Scopus SJRQ1Food Price Bubbles: Food Price Indices of Turkey, the FAO, the OECD, and the IMF
Akyol Özcan, Kübra
Food price bubbles are a phenomenon in which the cost of some food items or food commodities climbs quickly and unreasonably before collapsing due to reasons such as speculation, supply and demand imbalances, meteorological occurrences, and governmental actions. Governments and academics keep an eye on food prices to spot and address these bubbles. The aim of this paper is to analyze the food price bubble phenomenon despite the global slowdown by examining its origins, consequences, and policy solutions. The study’s contribution lies in its investigation of the presence of a potential bubble formation in food prices, which have experienced a surge globally and particularly in Turkey in recent years. The research examines the behavior of bubble formation in food prices in Turkey, the FAO, the OECD, and the IMF between 1992 and 2022 using the ADF, SADF, and GSADF tests. These tests can help identify when asset prices deviate significantly from their fundamental values and may be at risk of a sharp correction. The TUR, FAO, OECD, and IMF variables all show distinct bubble formations, with the TUR variable having 130 periods from 1995 to 2006, the FAO having 8 price bubble occurrences, the OECD having 12 different bubble formations, and the IMF having 4 distinct bubble formations. The results indicate the existence of food price bubbles that demonstrate disparities from their inherent values grounded in market fundamentals.
AtıfScopus2WoS2OpenAlex2İncele - MakaleAçık Erişim2022Scopus SJRQ1Optimization of Ultrasonic Extraction of Nutraceutical and Pharmaceutical Compounds from Bee Pollen with Deep Eutectic Solvents Using Response Surface Methodology
Çelik, Saffet; Kutlu, Naciye; Gerçek, Yusuf Can; Bayram, Sinan; Pandiselvam, Ravi; Bayram, Nesrin Ecem
In recent years, there has been increasing interest in green extraction methods and green solvents due to their many advantages. In this study, the effects of an ultrasonic extraction method and deep eutectic solvents (DESs) on the extraction of different bioactive substances from bee pollen were investigated. In this regard, the effects of process variables such as the molar ratio of the DES (1, 1.5, and 2), sonication time (15, 30, and 45 min), and ultrasonic power (90, 135 and 180 W) on total individual amino acids, total individual organic acids, and total individual phenolic compounds were investigated by response surface methodology (RSM). The optimal conditions were found to be a molar ratio of 2, sonication time of 45 min, and ultrasonic power of 180 W (R2 = 0.84). Extracts obtained via the maceration method using ethanol as a solvent were evaluated as the control group. Compared with the control group, the total individual amino acid and total individual organic acid values were higher using DESs. In addition, compounds such as myricetin, kaempferol, and quercetin were extracted at higher concentrations using DESs compared to controls. The results obtained in antimicrobial activity tests showed that the DES groups had broad-spectrum antibacterial effects against all bacterial samples, without exception. However, in yeast-like fungus samples, this inhibition effect was negligibly low. This study is the first to evaluate the impact of DESs on the extraction of bioactive substances from bee pollen. The obtained results show that this innovative and green extraction technique/solvent (ultrasonic extraction/DES) can be used successfully to obtain important bioactive compounds from bee pollen.
AtıfScopus33WoS28OpenAlex36İncele - MakaleAçık Erişim2023Scopus SJRQ2Magnetic Force Performance of Hybrid Multisurface HTS Maglev System With Auxiliary Onboard PMs
Ozturk, U. Kemal; Abdioglu, Murat; Mollahasanoglu, Hakki
The vertical levitation force, guidance force, and magnetic stiffness values, and thus the loading capacity and movement stability of high-temperature superconducting (HTS) Maglev systems, are aimed to be increased in this study by using auxiliary permanent magnets (PMs) in the onboard unit together with the multisurface HTS-permanent magnetic guideway (PMG) arrangement (hybrid multisurface arrangement). First, the magnetic levitation force, guidance force, and stiffness performances of the hybrid multisurface arrangement were investigated at different field cooling heights (FCH). Then, to compensate for the negation of instability that results from the higher repulsive force between the onboard PMs and the PMG and to obtain an optimal magnetic field medium, we have changed the vertical position of the auxiliary onboard PMs (ZPM) to ZPM = 0, 2, and 4 mm, at the cost of a bit of adecrement in the vertical levitation force. The bigger levitation force, together with the guidance force values for FCH = 25 mm and ZPM = 0 mm, indicates that the hybrid multisurface HTS-PMG arrangements are beneficial to increasing the practical applicability of Maglev systems.
AtıfScopus16WoS14OpenAlex14İncele - MakaleYayıncıda açık erişim2024Scopus SJRQ3Antioxidant effect of Rosa pimpinellifolia L. fruit extract on cholestatic liver injury: an experimental study
Demircioglu, Mahmut Kaan; Demircioglu, Zeynep Gul; Cakir, Ozlem; Yanar, Karolin; Ozguven, Muveddet Banu Yilmaz; Atukeren, Pinar; Gulcicek, Osman Bilgin; Citgez, Bulent; Yazici, Pinar
BACKGROUND: Antioxidants have been considered a rational curative strategy to prevent and cure liver diseases involving oxidative stress. An acute obstructive jaundice rat model was established to investigate the in vivo hepatoprotective efficacy of Rosa pimpinellifolia L. METHODS: The experimental jaundice model was performed by binding the main bile duct in 25 male Sprague-Dawley rats. All rats were randomly divided into five groups: first group: laparotomy-sham-only, second group: biliary tract binding (control), and third, fourth, and fifth groups: treatment groups with 250, 500, and 750 mg/kg fruit extracts daily, respectively. RESULTS: Considering dosage, although there was no significant therapeutic effect in the 250 mg/kg of Rosa pimpinellifolia L. group, the best results were found in the 500 mg/kg dose group, while results in the 750 mg/kg dose group showed consistent correlation with proinflammatory response. With regard to biochemical parameters, lipid hydroperoxide level in the rat serum and liver tissue was significantly decreased in all treatment groups. Amadori products, which are one of the early markers of glycol-oxidative stress, showed statistical significance in the treatment. CONCLUSION: It was revealed that the antioxidant effect of Rosa pimpinellifolia L. was more prominent in the early stages of hepatic injury secondary to oxidative stress.
AtıfScopus4WoS1OpenAlex2İncele - MakaleYalnız künye2024Scopus SJRQ1Optimum design of steel frames against progressive collapse by guided simulated annealing algorithm
Tayfur, Bilal; Daloğlu, Ayşe T.
In this paper, a Guided Simulated Annealing (GSA) algorithm is presented to optimize 2D and 3D steel frames against Progressive Collapse. Considering the nature of structural optimization problems, a number of restrictions and improvements have been applied to the decision mechanisms of the algorithm without harming the randomness. With these improvements, the algorithm aims to focus relatively on the flawed variables of the analyzed frame. Besides that, it is intended to be more rational by instituting structural constraints on the sections to be selected as variables. In addition to the LRFD restrictions, the alternate path method with nonlinear dynamic procedure is used to assess the risk of progressive collapse, as specified in the US Department of Defense United Facilities Criteria (UFC) Design of Buildings to Resist Progressive Collapse. The entire optimization procedure was carried out on a C# software that supports parallel processing developed by the authors, and the frames were analyzed in SAP2000 using OAPI. Time history analyses of the removal scenarios are distributed to the processor cores in order to reduce computational time. The GSA produced 3% lighter structure weights than the SA (Simulated Annealing) and 4% lighter structure weights than the GA (Genetic Algorithm) for the 2D steel frame. For the 3D model, the GSA obtained 3% lighter results than the SA. Furthermore, it is clear that the UFC and LRFD requirements differ when the acceptance criteria are examined. It has been observed that the moment capacity of the entire frame is critical when designing according to UFC.
AtıfScopus5WoS5OpenAlex1İncele - MakaleAçık Erişim2023Scopus SJRQ3Examination of the Effectiveness of School Leadership: A Second-order Meta-analysis Study
Kaya, Metin
This study aimed to examine the effectiveness of school leadership by exploring the relationships between various school leadership models and practices and different school outcomes, including organizational, teacher, and student outcomes. Data for this study were retrieved from multiple databases, including Web of Science, Scopus, ERIC, Academic Search Ultimate, and TR Dizin-Turkish national index. The analysis synthesized findings from 23 meta-analysis studies, utilizing second-order meta-analysis with the random-effects model. The study revealed a significantly positive relationship between school leadership and school outcomes, with a high level of correlation (mean effect size: 0.46). Additionally, this relationship varied significantly based on the type of school leadership, school outcome, and the quality of the studies conducted.
AtıfScopus2WoS1OpenAlex2İncele - MakaleYalnız künye2024Scopus SJRQ3LOGARITHMIC SEMI P-FUNCTION AND SOME NEW INEQUALITIES
Kadakal, Mahir; İşcan, İmdat
In this study, we introduce and study the concept of logarithmic semi P functions and their some algebraic properties. Then, we obtain the Hermite-Hadamard integral inequality for the log semi-P-functions. After that, we obtain some new inequalities by using Hölder, Hölder-İşcan and power-mean integral inequalities and show that the result obtained with Hölder-İşcan inequality gives better approach than the Hölder integral inequality. Some applications to special means of real numbers are also given.
AtıfScopus1İncele - MakaleYalnız künye2024Scopus SJRQ1Middle School Students’ Problem Solving Performance: Identifying the Factors that Influence It
Öztürk, Mesut; Sarikaya, İsmail; Ada Yıldız, Kübra
This research was carried out to examine the serial mediation role of mathematics self-efficacy and metacognition for problem-solving in the effect of reading comprehension on problem-solving. The relational research model, one of the quantitative research designs, was used in the study. A total of 699 middle school students studying in official public schools in Turkey participated in the study. SPSS and PROCESS macros were used in the analysis of the data of the study. The study revealed that reading comprehension, mathematics self-efficacy, and metacognition were related to problem-solving. The result of the study showed that mathematics self-efficacy and metacognition significantly mediate the relationship between reading comprehension and problem-solving.
AtıfScopus10WoS7OpenAlex19İncele - MakaleAçık Erişim2024Global Existence in a Predator-Prey Model with Nonlinear Indirect Chemotaxis Mechanism
Akkoyunlu, Ebubekir
One of the fundamental processes in ecology is the interaction between predator and prey. Predator-prey interactions refer to the relative changes in population density of two species as they share the same environment and one species preys on the other. There are many studies global existence or blow-up of solutions on the predator-prey model. Our this paper related to the predator-prey model with nonlinear indirect chemotaxis mechanism under homogeneous Neumann boundary conditions. We establish the global existence and boundedness of classical solutions of our problem by using parabolic regularity theory. Namely, firstly we show that and boundedness in for some, then we obtain the-bound of and by using Alikakos-Moser iteration. Thus, it is proved that the model has a unique global classical solution under suitable conditions on the parameters in a smooth bounded domain.
AtıfScopus1OpenAlex1İncele - MakaleAçık Erişim2024Scopus SJRQ2A Numerical Study of Topography and Roughness of Sloped Surfaces Using Process Simulation Data for Laser Powder Bed Fusion
Aydogan, Beytullah; Chou, Kevin
The simulation of additive manufacturing has become a prominent research area in the past decade. Process physics simulations are employed to replicate laser powder bed fusion (L-PBF) manufacturing processes, aiming to predict potential issues through simulated data. This study focuses on calculating surface roughness by utilizing 3D surface topology extracted from simulated data, as surface roughness significantly influences part quality. Accurately predicting surface roughness using a simulation remains a persistent challenge. To address this challenge, the L-PBF technique with two different cases (pre- and post-contouring) was simulated using two-step process physics simulations. The discrete element method was utilized to simulate powder spreading, followed by the Flow-3D melting simulation. Ten layers were simulated at three different linear energy density (LED) combinations for both cases, with samples positioned at a 30-degree angle to accommodate upskin and downskin effects. Furthermore, a three-dimensional representation of the melted region for each layer was generated using the thermal gradient output from the simulated data. All generated 3D layers were stacked and merged to consolidate a 3D representation of the overall sample. The surfaces (upskin, downskin, and side skins) were extracted from this merged sample. Subsequently, these surfaces were analyzed, and surface roughness (Sa values) was calculated using MATLAB. The obtained values were then compared with experimental results. The downskin surface roughness results from the simulation were found to be within the range of the experimental results. This alignment is attributed to the fact that the physics simulation primarily focuses on melt pool depth and width. These promising findings indicate the potential for accurately predicting surface roughness through simulation.
AtıfOpenAlex1İncele - MakaleYalnız künye2023Scopus SJRQ2Free vibration and buckling of functionally graded porous beams using analytical, finite element, and artificial neural network methods
Turan, Muhittin; Uzun Yaylacı, Ecren; Yaylacı, Murat
In this study, an analytical solution based on the first-order shear deformation theory was performed for free vibration and buckling analysis of functionally graded porous beams (FGM-P) subjected to various boundary conditions. Also, this problem is solved by using finite element (FEM) and artificial neural network (ANN) methods. Here a Ritz-based analytical solution is used, and different polynomial series functions are proposed for each boundary condition. Lagrange's principle was used while deriving the equations of motion. A power-law rule describes the variation of the beam's materials in volume. The normalized fundamental frequencies and critical buckling loads are obtained for various boundary conditions, power-law index (k), slenderness (L/h), porosity coefficient (e), and porosity distribution (FGM-P1, FGM-P2). The polynomial series functions used in this study were verified with the literature, and the numerical results obtained were compared with FEM and ANN. The results obtained are quite compatible with each other.
AtıfScopus140WoS136OpenAlex101İncele - MakaleAçık Erişim2023Scopus SJRQ1The effect of local food consumption of domestic tourists on sustainable tourism
Apak, Ömer Ceyhun; Gürbüz, Ahmet
This research aims to determine the effect of local food consumption of domestic tourists on sustainable tourism. In addition, the study also aims to: reveal the impact of local foods on economic, socio-cultural, and environmental sustainability. In this context, data were collected from 394 domestic tourists visiting the provinces of the Eastern Black Sea region (Artvin, Bayburt, Gumushane, Trabzon and Rize). This research was designed in accordance with the correlational research method, one of the quantitative research designs. The research data were tested using structural equation modeling, which is commonly used in the social and behavioral sciences. As a result, it was found that local food has a statistically significant and positive effect on sustainable tourism. In addition, local food was found to have a positive effect on the subscales (economic, socio-cultural and environmental) of sustainable tourism.
AtıfScopus81WoS62OpenAlex87İncele
