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KENTSEL YOLLARDA ŞERİT KAPAMA VEYA ŞERİT DARALTMA UYGULAMALARININ TRAFİĞE OLAN ETKİLERİNİN KÂĞITHANE VE ÜMRANİYE İLÇELERİ ÖZELİNDE KARŞILAŞTIRMALI OLARAK DEĞERLENDİRİLMESİ
No full textBildiriye bu link üzerinden erişebilirsiniz:https://drive.google.com/file/d/12IZSDxN-s6Fs7Dbbvik2h03Mx1FaXeZ4/view?usp=sharing </p
Tailoring Ti3C2Tx MXene multilayers for biomaterial integration: synthesis, characterization, and cytotoxicity
No full textThis study examines the biomedical potential of Ti3C2Tx MXene multilayers, which are synthesized from the Ti3AlC2 MAX phase using different wet chemical etching methods: HF, LiF/HCl, and NaF/HCl. The effects of each etchant on the morphology, interlayer spacing, surface terminations, and defect structures are thoroughly analyzed using techniques such as XRD, FESEM, EDS, FTIR, and Raman spectroscopy. Cytotoxicity tests based on assays using L929 fibroblast cells demonstrate a strong relationship between surface groups and biocompatibility. Among the tested variants, NaF/HCl-etched MXenes showed smoother multilayers with less structural damage, optimized surface terminations, and lower toxicity to cells compared to HF-etched multilayers, which exhibited more structural damage, surface oxidation, and higher toxicity. These results highlight the importance of selecting the right etching method in tailoring MXene multilayers for use in ceramic-based biomedical scaffolds and implantable devices, offering guidance for future development of biocompatible materials
A novel approach based on embedding Green’s functions into fixed point iterations for solving boundary value problems
No full textIn this paper, a novel numerical method based on embedding Green’s functions into classical fixed point iterations for solving a class of boundary value problems (BVPs) was developed. The iterative algorithms are implemented by embedding suitable integral operators on them. Numerical examples were given to demonstrate the applicability and efficiency of the methods. Furthermore, we prove that the Picard–Ishikawa–Green method developed by embedding Green’s functions into the Picard–Ishikawa hybrid iteration (G. A. Okeke, Convergence of the Picard-Ishikawa hybrid iterative process with applications, Afrika Matematica 30, 817–835 (2019)) converges faster than several methods. The results show that the new approach provides approximations that are highly accurate
Hybrid heroes of water treatment: The rise of biochar-modified metal organic frameworks
No full textBiochar-metal organic framework (BC-MOF) composites are highly promising for water treatment due to their synergistic properties. In this regard, this review paper highlights their outstanding performance in removing various pollutants from water. The applications of these composites cover various environmental remediation processes, such as adsorption, photocatalysis, persulfate activation, and Fenton-like degradation. BC-MOF composites have demonstrated high performance in environmental applications, achieving pollutant removal efficiencies exceeding 90 % through adsorption and photocatalytic degradation. Moreover, degradation processes through advanced oxidation pathways, which produce active radicals, such as hydroxyl and superoxide radical-mediated breakdowns, significantly enhance the mineralization of organic pollutants. Many composites also retained >80 % of their initial capacity after 4–6 cycles, indicating good reusability. Overall, BC-MOF composites present a sustainable, high-performance solution for contaminant removal, with broad applicability against antibiotics, dyes, heavy metals, pesticides, and fluoride ions
Congo Red photodegradation using magnesium borate under UV irradiation and modelling by the Box Behnken method
No full textWaste toner particles based dispersive solid phase extraction for the trace determination of cadmium in cinnamon tea samples by flame atomic absorption spectrometry
No full textThis study presents a dispersive solid phase extraction (DSPE) protocol for the sensitive and accurate determination of trace levels of cadmium ions (Cd2+) by flame atomic absorption spectrometry (FAAS). Toner particles obtained from used printer cartridges were used as sorbent material for preconcentration of Cd2+ ions. Optimization studies were performed univariately for the achievement of the highest extraction efficiency and the limit of detection (LOD) was found to be 0.55 µg L-1 under optimal operating conditions. By comparing the slopes of the linear plot equations for FAAS and waste toner-based DSPE-FAAS systems, the increase in sensitivity was calculated to be 40.9 times. The feasibility of the developed method was evaluated by spiking recovery studies on cinnamon tea samples and good recovery results between 90.4 % and 119.0 % determined by the matrix matching calibration strategy showed that the method is applicable to cinnamon tea and similar matrices
A new asymmetric phthalocyanine-based chemosensor for the detection of ultra trace amount of copper (II) ions in environmental samples: comprehensive complex characterization and DFT analysis
No full textWhile Cu2+ ions are essential for various biological and physiological processes, they can also induce severe neurodegenerative disorders, such as Alzheimer's and Parkinson's disease, when present in excess. Therefore, there is a pressing need to develop novel chemical sensors capable of selectively and sensitively detecting these ions in environmental samples. In this study, an A3B-type asymmetric phthalocyanine-based sensor, PCA-ZnPc-5, was developed by integrating tert-butyl groups and pyrazole moieties. These units play an active role in suppressing aggregation and increasing the solubility of the sensor molecule, as well as functioning as selective receptors against Cu2+, respectively. PCA-ZnPc-5 facilitated the detection of Cu2+ ions at the nanomolar level in environmental matrices, with no interference from other species. The applied fluorescence-based method yielded in a detection limit of 7.38 nM and an ultra-fast response time of one second. A notably significant binding constant of 4.89 × 106 M−1 confirmed the strong interaction between PCA-ZnPc-5 and Cu2+. The recovery percentages ranged from 97.9 % to 102.9 %, indicating the efficacy and suitability of PCA-ZnPc-5 for the analysis of Cu2+ in actual samples. The binding stoichiometry (1:1 ratio) and mechanism were confirmed by a comprehensive analytical approach including UV–Vis, FT-IR, MALDI-TOF Spectroscopy, and Job's Method. The 3-dimensional geometries of the probe and its Cu2+ complex were elucidated through DFT calculations, which also revealed the binding mode and the frontier molecular orbitals of the system
Exponential stability of switched nonlinear time-delay systems combining Lyapunov–Krasovskii, Halanay and Razumikhin approaches
No full textIn this study, we propose novel methods to ensure the exponential stability of switched nonlinear time-delay systems based on Lyapunov–Krasovskii, Lyapunov–Halanay and Lyapunov–Razumikhin approaches. We derive new average dwell-time bounds to establish global exponential stability by integrating Lyapunov–Krasovskii functionals and Lyapunov–Halanay functions under specified compatibility conditions. These conditions require an interchange between Lyapunov–Krasovskii functionals and Lyapunov–Halanay functions, with bounded integral operators. Additionally, we extend Halanay's inequality to accommodate functions with growth, enabling its applicability to scenarios where growth is observed. Using the method in Loko etal (2024), we construct Lyapunov–Krasovskii functionals from Lyapunov–Razumikhin functions, to establish exponential stability within a constrained switching framework. Illustrative examples demonstrate the effectiveness of our methodologies in various scenarios involving discrete, distributed, and historywise delays, highlighting the applicability of the proposed techniques
Trait Anxiety in Children and Adolescents: Alternative Models of the Role of Cognitive Flexibility and Intolerance of Uncertainty
No full textAnxiety disorders are among the most prevalent mental health problems in children and adolescents, affecting their academic and social functioning, family dynamics, and overall quality of life. Guided by the cognitive model of anxiety, this study aimed to examine how cognitive flexibility and intolerance of uncertainty contribute to trait anxiety in children and adolescents. This study was conducted with a total of 932 children and adolescents aged between 10 and 19 in Turkiye (with a mean age of 14.47 and a standard deviation of 2.16). Results indicate a positive correlation between anxiety and intolerance of uncertainty, with higher levels of intolerance of uncertainty corresponding to increased anxiety levels. Additionally, anxiety shows a negative correlation with cognitive flexibility, suggesting that flexible thinking in stressful situations is associated with lower levels of anxiety and intolerance of uncertainty. In addition, there is a negative relationship between cognitive flexibility and intolerance of uncertainty. Cognitive flexibility and intolerance of uncertainty explain 49.6% of the variance in trait anxiety in children and adolescents. The findings highlight the importance of cognitive flexibility and intolerance of ambiguity in promoting mental well-being among children and adolescents and suggest implications for interventions aimed at increasing cognitive flexibility and reducing intolerance of ambiguity as protective and risk factors for anxiety and its reduction in this population
DC NANO ŞEBEKELERDE GÜÇ KALİTESİNİN İYILEŞTİRİLMESİ: BATARYALI PSFB VE BATARYASIZ BOOST DÖNÜŞTÜRÜCÜ TOPOLOJİLERİNİN KARŞILAŞTIRMALI ANALİZİ
No full textGünümüzdeçevre dostu yenilenebilir enerji kaynaklarının hızla yaygınlaşmasıyla birlikte,bu kaynakların enterkonnekte şebekeden bağımsız veya şebeke ile etkileşimliolarak verimli bir şekilde kullanıldığı DC nano şebeke uygulamaları büyük birönem kazanmıştır. Ancak güneş enerjisi gibi meteorolojik koşullara bağlı vekesintili karakteristiğe sahip kaynakların, yük tarafında kararlı ve kesintisizbir DC bara gerilimi sağlamada tek başına yetersiz kalması, sisteme enerjidepolama birimlerinin ve gelişmiş güç elektroniği dönüştürücülerininentegrasyonunu zorunlu kılmaktadır. Bu çalışmada, 96 V giriş gerilimine sahipdüşük gerilimli kaynaklardan standart 400 V DC bara gerilimi elde edilmesineyönelik iki farklı güç dönüşüm yapısı MATLAB/Simulink ortamında detaylı olarakmodellenmiş ve performansları karşılaştırmalı olarak analiz edilmiştir. İlksenaryoda, 10 kW gücündeki fotovoltaik (PV) sistem, herhangi bir enerjidepolama birimi olmaksızın geleneksel Yükseltici (Boost) dönüştürücü üzerindenDC barayı besleyecek şekilde tasarlanmıştır. İkinci ve önerilen senaryoda ise,enerji sürekliliğini sağlamak amacıyla sisteme 5 kWh kapasiteli bir bataryagrubu entegre edilmiş ve güç aktarımı, galvanik izolasyon sağlaması ve yüksekfrekanslarda anahtarlama kayıplarını minimize eden yumuşak anahtarlama (ZVS)yeteneği nedeniyle Faz Kaydırmalı Tam Köprü (PSFB) dönüştürücü topolojisi ilegerçekleştirilmiştir. Her iki sistem, güneş ışınımının ani değişim gösterdiğidinamik koşullar altında test edilmiştir. Gerçekleştirilen simülasyonsonuçları, bataryasız Boost yapısının ışınım azaldığında 400 V bara geriliminireferans değerde sabit tutmakta başarısız olduğunu ve sistemde ciddi gerilimçökmeleri yaşandığını göstermiştir. Buna karşılık, önerilen bataryalı PSFByapısının, PV kaynağındaki güç dalgalanmalarını batarya desteğiyle sönümlediği,izole yapısı sayesinde daha güvenli bir işletim sunduğu ve yük tarafındakesintisiz ve referans değere yakın bir 400 V gerilim sağladığı tespitedilmiştir. Elde edilen bulgular, DC nano şebekelerde enerji sürekliliği,sistem kararlılığı ve güç kalitesi için batarya entegrasyonunun ve yüksekverimli izole dönüştürücü topolojilerinin kritik bir rol oynadığını ortayakoymaktadır.</p