DSpace @ Recep Tayyip Erdoğan Üniversitesi Akademik Açık Arşiv
Not a member yet
12203 research outputs found
Sort by
The ovoprotective effect of quercetin against methotrexate-induced injury by targeting Nrf2 signalling in female rats
No full textAlthough methotrexate (MTX) is a widely used anti-cancer drug in chemotherapy, its clinical use is limited due to its toxicity to many organs, including the ovaries. Quercetin (QUE), a natural flavonol, has known antioxidant and anti-inflammatory effects, but QUE's effects on endoplasmic reticulum stress (ERS) and nuclear factor erythroid 2-related factor 2 (Nrf2) pathways in MTX-induced ovotoxicity remain unclear. Therefore, this study was designed to investigate the therapeutic effect of QUE in MTX-exposed rats, including the ERS and Nrf2 signalling pathways. Five groups of six rats were formed as follows: control, MTX (20 mg/kg), MTX+low dose QUE (5 mg/kg), MTX+high dose QUE (10 mg/kg) and only high dose QUE (per se). Colourimetric methods were used to determine the levels of reproductive hormones in serum samples, and markers of oxidative stress (OS), inflammation, ERS, Nrf2 pathway and apoptosis in ovarian tissue. MTX administration resulted in dramatic histopathological findings in ovarian tissue and increased OS, inflammation, ERS and apoptosis associated with Nrf2 inhibition. Conversely, QUE treatment reversed the pathological biochemical and histological changes induced by MTX by modulating the Nrf2 pathway. Taken together, the results of this study provide the first evidences that QUE can ameliorate biochemical and histopathological findings in MTX-induced ovotoxicity. This needs to be supported by more comprehensive mechanistic studies before moving to clinical application
Investigation of antioxidant properties of propolis products collected from different regions
No full textPropolis, a sticky bee hive product collected from resinous plant sources by Apis mellifera bees, exhibits a wide range of biological and pharmacological properties, primarily attributed to its rich composition of bioactive constituents, including phenolic acids, esters, and flavonoids. In this study, the antioxidant properties of 76 liquid propolis solutions from 18 different countries were investigated based on their dry matter, total phenolic and total flavonoid contents, antioxidant capacities, and phenolic profiles. The antioxidant activities of propolis from various geographic regions, including Latvia, Croatia, New Zealand, San Marino, Russia, France, Romania, Italy, Estonia, Brazil, Belgium, Germany, Slovenia, Japan, the United States of America (USA), the United Arab Emirates (UAE), Spain, and Korea, were compared. Total phenolic and flavonoid contents, as well as total antioxidant capacity (Cupric Reducing Antioxidant Capacity-CUPRAC method), were analyzed by spectrophotometry, and the major constituents were investigated by liquid chromatography-mass spectrometry (LC-MS/MS). Antioxidant test results indicated that 29 products scored below 10 mg Trolox equivalent (TE)/mL, and only 14 were scored above 100 mg TE/mL. The results showed that the total phenolic content of the samples ranged from 0.1 to 107.5 mg Gallic acid equivalent (GAE)/mL, while total flavonoid content varied between 0.1 and 174.5 mg Catechin equivalent (CE)/mL. Based on the CUPRAC assay, total antioxidant capacity values ranged from 0.1 to 492.3 mg TE/mL. Among the 76 analyzed samples, nine products exhibited antioxidant capacity values exceeding 150 mg TE/mL. In all of these samples, phenolic profiling confirmed the presence of propolis, and the analytical results were consistent with the information declared on the product labels. Hence, this study provides a comprehensive, real-market evaluation of commercial propolis products by integrating spectrophotometric assays with LC-MS-based targeted metabolomics profiling, highlighting formulation- and product type-driven differences in phenolic composition and antioxidant capacity beyond geographical origin
Çay Yaprağının Hasat İşlemleri
No full textÇay Tarımı Dersi 7. Hafta Ders Notu Konusu : Çay Yaprağının Hasat İşlemler
Foreign direct investment and growth impact on pollution in the EU countries: empirical analysis of the EKC and pollution halo hypothesis
No full textForeign direct investment inflows are an important factor in the development of countries. Rising FDI can cause unexpected environmental consequences by changing technology use or energy consumption. The study examined the relationships between fossil energy consumption, carbon emission rate, and FDI for 27 European Union countries in the period 2006–2021. In addition, for the first time in this study, EU countries were divided into two according to their income levels and re-analysed. Panel data method and robust Driscoll and Kraay (1998) estimator were used in empirical analyses. The research findings show that a one-unit increase in FDI across EU countries results in a 0.055% increase in GDP and fossil fuel consumption, respectively, and a −0.155% decrease in pollution. These results support the pollution halo hypothesis, which posits that foreign direct investment reduces environmental degradation. The research findings support the pollution halo hypothesis, which states that FDI reduces environmental degradation. It also confirms that the EKC hypothesis, which states that there is an inverted U-shaped relationship between pollution and GDP, is valid in 27 EU countries. However, it has been determined that the pollution haven hypothesis is valid in low-income EU countries. Low-income EU countries should encourage more foreign investment in technology-intensive and environmentally friendly areas and develop various environmental regulations in this direction. The results obtained from the research are expected to provide benefits and insights to policy makers, researchers, and industrialists to increase environmental awareness. The results suggest that low-income EU countries should encourage technology-intensive and environmentally friendly investments, improve green financing and investment conditions, and develop regulations to strengthen environmental standards, so that they can limit environmental degradation while preserving the general welfare-enhancing benefits of FDI
Anti-gender normativity and advocacy in Turkey - making a case for practice diffusion
No full textThis article offers a practice-oriented perspective on the near-simultaneous rise of anti-genderism in the post-2010 context. Using the Turkish case, it argues that normative isomorphism across different locales is not always the result of recent norm diffusion; their simultaneous and isomorphic emergence can be attributed to the diffusion of practices that enact pre-existing normative frameworks. Empirically speaking, this would mean re-reading the rise of anti-genderism as also a process of practice diffusion, no doubt, within the broader context of the growing influence of right-wing populism and illiberalism. The research suggests focusing on the diffusion of practices rather than norms per se, allowing for a more nuanced understanding of global normative similarities and claims of globality
Innovative molecular architecture of a new Hg2+/Cu2+-dual chemosensor based on functionalizable chromenylium-cyanine framework
No full textA novel chromenylium-cyanine based near-infrared (NIR) and dual chemosensor (NIR9) has been developed for the highly sensitive and selective detection of mercury (Hg2+) and copper (Cu2+) ions. The NIR9 is the first example of NIR probes developed for independently analysis of Hg2+ and Cu2+ in real samples. The probe exhibits turn-on fluorescence and ratiometric UV–Vis absorption and colorimetric responses for Hg2+. It also displays a turn-off UV–Vis absorption signal to Cu2+. Upon interaction with Hg2+, NIR9 undergoes a desulfurization-induced spirolactam ring opening, resulting in a strong fluorescence emission at 750 nm and a visible color change from yellow to green, with a detection limit as low as 0.02 μM. For Cu2+ detection, the probe shows a unique absorbance decrease at 380 nm, enabling quantification with a detection limit of 0.01 μM. The sensing capability of NIR9 is supported by theoretical DFT studies and further validated through successful applications in real environmental (water and food) and biological (A549 cells) samples. Additionally, the probe enables smartphone-assisted detection of Hg2+, promoting field-deployable analytical capabilities. This work introduces a next-generation multiplexed NIR chemosensor with high versatility, selectivity, and sensitivity for environmental and biomedical applications
Experimental evaluation of thermal and flow characteristics of boiling phenomenon in expanding double pool heat sink with micro pins
No full textGeometrical-based interventions have great potential and research interest for improvement of flow boiling performance regarding micro-scale heat sinks due to intricate relation between geometry and flow physics. In relevant systems, disadvantages related to pressure drop must be eliminated, and an enhancement must be provided in heat transfer, simultaneously. In this regard, facilitating vapor evacuation by providing additional forces and as well as additional mechanisms and improving surface interaction with liquid phase are important physical phenomena that must be ensured for micro-boiling systems, and these phenomena can be realized by suitable geometrical designs. Thus, here, a novel heat sink (expanding double pool heat sink, EDP) was introduced, and flow boiling characteristics were revealed comparing via ordinary design (UPF). Heating power and mass flux were operational parameters, with range of them are 100–300W; (148 to 460 kWm-2) and 175–275 kgm-2s-1, respectively. The EDP increases heat transfer coefficients up to 84.9% for G=175 kgm-2s-1, 350% for G=225 kgm-2s-1 and 141% for G=275 kgm-2s-1, compared to UPF. For all mass-fluxes, EDP presents a lower pressure drop up to 40.1%. Performance evaluation criterion of EDP changes between 1.2 and 5.3 (reference is UPF). The unbalanced surface tension force plays a critical role
Система виробництва спiрально намотаних надпровiдних кабелiв
No full textThis study presents an advanced production system for helically wound superconducting cables. The developed system addresses critical challenges in high-current applications (such as power transmission, fusion reactors, and space technologies) by combining modular design with precision engineering solutions. It is directly applicable to the production of superconducting magnets required for particle accelerators and high-energy detector systems. Key innovations of the system include an adjustable tension control mechanism (with a range of 10–20 Nm), multi-axis synchronization (seven-axis motion control), and configurable winding parameters (helix angle between 10∘ and 75∘, diameter range of 6–25 mm). The production platform integrates up to 16 independent tensioning units and provides precision tension management via an adaptive control mechanism. The output of the device confirms the system’s ability to produce industrial-quality superconducting cables while minimizing mechanical deformation. These technological advancements provide a strong foundation for integration into large-scale infrastructure projects in high-energy physics
Voltage-tunable, femtometer-precision cantilever displacement and squeezing in a plasmomechanical system
No full textWe present an elegant method for continuous electrical-tuning of the cantilever position in a plasmomechanical system without changing the plasmonic gap size. Cantilever is the mechanical oscillator coupled to the plasmonic gap intensity. The same method allows the voltage-tuning of the uncertainty in the cantilever position (quadrature squeezing). Recent experiments achieve nanometer-scale bending of cantilevers using electrostatic actuators. Unlike those works, we do not bend the cantilever, which can introduce noise into the oscillations and limit the response time. Instead, we electrically tune the intensity in the plasmonic gap, thus the plasmomechanical coupling, through Fano resonance. This allows continuous control of the cantilever position in units of the mechanical oscillator's natural length, which is about 30 fm in those experiments. Using this approach, the coupling strength can be varied by 2 orders-of-magnitude with a voltage change of only 1 V. The response time is in the picosecond range
Left ventricular and left atrial strain characteristics in patients with familial mediterranean fever receiving long-term colchicine therapy
No full textBackground: Familial Mediterranean fever (FMF) is a chronic autoinflammatory disorder characterized by sustained systemic inflammation that may affect cardiac structure and function. Colchicine is the cornerstone of FMF therapy and has cardiovascular benefits in inflammatory settings. Methods: This cross-sectional study enrolled 106 participants: 53 patients with FMF receiving long-term colchicine therapy and 53 age- and sex-matched controls. Participants underwent transthoracic echocardiography with speckle-tracking imaging. Conventional parameters and strain-derived indices of the left ventricular (LV) and left atrial (LA) function were assessed. Correlation analyses and multivariable linear regression models were used to evaluate the association between FMF presence and cardiac strain parameters. Results: The LV ejection fractions were comparable between the groups. The FMF group showed thinner ventricular walls and larger chamber dimensions than the control group. Patients with FMF exhibited higher LA reservoir strain, while conduit and contractile atrial contributions were reduced, as shown by lower passive and active emptying fractions and reduced LA ejection fraction. LA volumes and stiffness indices were lower in the FMF group, indicating smaller and more compliant atrial structures. Left ventricular global longitudinal strain (LVGLS) was more negative in patients with FMF, indicating preserved LV longitudinal systolic function. FMF was independently associated with LVGLS and LA strain parameters after adjusting for cardiovascular risk factors. Conclusions: In patients with FMF receiving long-term colchicine therapy, cardiac strain imaging showed preserved LV longitudinal function and distinct LA mechanics with preserved reservoir strain but reduced conduit and contractile function. Strain echocardiography may provide insights into cardiac involvement in well-controlled FMF, although prospective studies are needed to clarify the clinical significance of these findings