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Öğe Detection of Diazinon Organophosphates Using Magnetoelastic Sensor(Ieee-Inst Electrical Electronics Engineers Inc, 2022) Atalay, Selcuk; Ates, Burhan; Balcioglu, Sevgi; Inan, Orhan Orcun; Kolak, Seda; Simsek, Murat; Kolat, Veli SerkanIn this study, 2826MB (Fe40Ni38Mo4B18) amorphous ferromagnetic ribbons were used as a magnetoelastic sensor (MES) to detect diazinon organophosphates (OP). Since enlarging the sensor surface area makes a significant contribution to the sensitivity of the sensor, nanofibers were coated on the sensor surface, and then, the nanofibers were functionalized with glutaraldehyde (GA) in order to covalently bind acetylcholinesterase (AChE) enzyme to the surface. It was found that binding of OPs to the AChE enzyme at the functional amorphous ribbon surface, a large change in the resonance frequency was observed. The results showed that functionalized MES shows a linear change according to the amount of OP detected in the range of 0-140 nL or 0-150 ppm in the solution.Öğe Diagnosis, Bacterial Density, Food, and Agricultural Applications of Magnetoelastic Biosensors: Theory, Instrumentation, and Progress(Springer, 2024) Balcioglu, Sevgi; Inan, Orhan Orcun; Kolak, Seda; Ates, Burhan; Atalay, SelcukMagnetoelastic biosensors have emerged as a promising technology for the sensitive and label-free detection of a wide range of biological analytes. These biosensors use the magnetoelastic effect, which describes how the mechanical properties of magnetostrictive materials change in response to a magnetic field. This effect is utilized to detect biological analytes by immobilizing specific recognition elements, such as antibodies or nucleic acids, on the magnetoelastic material's surface. The binding of target analytes to the recognition elements induces a mass change, leading to a shift in the resonance frequency of the magnetoelastic material. Magnetoelastic biosensors find applications across various fields, including medical diagnostics, environmental monitoring, and food safety. In medical diagnostics, they offer rapid and sensitive capabilities for detecting pathogens, biomarkers, and toxins. For environmental monitoring, they demonstrate the ability to detect pollutants and heavy metals. Furthermore, in ensuring food safety and quality, magnetoelastic biosensors detect allergens, pathogens, and contaminants effectively. Ongoing research and technological advancements suggest that these biosensors hold great potential for revolutionizing various fields, including healthcare, environmental monitoring, and food safety, contributing to improved disease diagnosis, environmental protection, and public health. This review article provides an overview of the principles, fabrication methods, diagnosis, bacterial density, food, and agricultural applications of magnetoelastic biosensors.Öğe Fabrication and characterization of a Vacodur49/PZT/Vacodur49 magnetoelectric sensor(Elsevier, 2025) Durmaz, Ergun; Inan, Orhan Orcun; Atalay, SelcukIn this study, we report for the first time the fabrication and characterization of a Vacodur49/PZT/Vacodur49 trilayer magnetoelectric (ME) sensor. Vacodur49, a cobalt-iron-vanadium alloy, was employed as the magnetostrictive component due to its high saturation magnetization and significant magnetostriction (70 ppm). Structural and magnetic analyses confirmed the crystalline quality, magnetic softness, and favourable anisotropy of the alloy. The fabricated device exhibited a strong resonance-enhanced ME coupling, achieving a maximum ME coefficient of 361 V center dot cm(-1)center dot Oe(-1) under an AC magnetic field of 0.047 Oe at similar to 49.2 kHz. The sensor demonstrated ultra-high sensitivity with a minimum detectable AC magnetic field of 100 pT, excellent linearity, and fast response. Compared to many other magnetic materials, Vacodur49 provides superior mechanical robustness and enables thicker magnetostrictive layers. These results establish Vacodur49 as a novel and promising material platform for next-generation ME sensors, with potential applications in biomedical diagnostics, ultra-low-field detection, and precision magnetic sensing technologies.Öğe Fabrication and characterization of functional chitosan/MXene composite films decorated with lead zirconate titanate nanoparticles(Elsevier Science Sa, 2025) Ulu, Oznur Dogan; Ulu, Ahmet; Birhanli, Emre; Pekdemir, Mustafa Ersin; Atalay, Selcuk; Gelir, Ali; Ates, BurhanThe current study is intended to enhance unique bioactive and eco-friendly composite films following a simple solvent-casting method by incorporating lead zirconate titanate nanoparticles (PZT NPs) with chitosan (CHS)/ MXene matrix. Different characterization techniques were used in the examination of the obtained composite films and the basic physicochemical properties, electrical properties, antioxidant and antibacterial activities of the composite films were determined. The swelling degree, water uptake, and water solubility of the CHS/ MXene/PZT composite films decreased with the incorporation of PZT NPs, whereas the thermal stability increased. When PZT NPs were added, the tensile strength and elongation at break of composite films reached 1.32 MPa and 29.32 %, respectively, which were obviously higher than that of CHS/MXene film. Meanwhile, composite film had moderate antioxidant properties, which, interestingly, decreased with increasing PZT NPs content. In contrast, the obtained composite films showed good antibacterial activity against E. coli (11.00-16.80 mm) and S. aureus (12.20-18.60 mm), which gradually increased with the amount of PZT NPs. Meanwhile, the order of antibacterial activity was found to be S. aureus > E. coli, showing the selectivity of composite films. These results will shed light on additive selection for functional composite films of several applications.Öğe Fabrication of a Portable Magnetic Microcantilever Using Fe40Ni38Mo4B18 Amorphous Ribbon and Its Application as a Humidity Sensor by Coating with TiO2 Nanotubes(Mdpi, 2024) Atalay, Selcuk; Erdemoglu, Sema; Yilmaz, Hatice Caglar; Mete, Emine; Inan, Orhan Orcun; Kolat, Veli SerkanMicrocantilevers (MCs) are highly sensitive sensors capable of detecting mass changes on the surface at the nanogram and even picogram scale. In this study, microcantilevers were fabricated for the first time using the Sodick AP250L Wire electrical discharge machining (EDM) from amorphous 2826MB (Fe40Ni38Mo4B18) ferromagnetic ribbons. This method is advantageous because it allows for the simultaneous production of a large number of microcantilevers, with about 100 MCs being produced in a single manufacturing process. Additionally, a straightforward and cost-effective measurement system was developed to measure the resonance frequency and frequency shift of the MC entirely through magnetic means, a technique not previously reported in the literature. To evaluate the performance of the MC, we employed it as a humidity sensor. For the TiO2-NT-coated MC, a frequency shift of approximately 202 Hz was observed when the humidity level changed from 5% to 95% relative humidity (RH).Öğe Fabrication of a Portable Magnetic Microcantilever Using Fe40Ni38Mo4B18 Amorphous Ribbon and Its Application as a Humidity Sensor by Coating with TiO2 Nanotubes (vol 10, 98, 2024)(Mdpi, 2025) Atalay, Selcuk; Erdemoglu, Sema; Yilmaz, Hatice Caglar; Mete, Emine; Inan, Orhan Orcun; Kolat, Veli Serkan[No abstract available]Öğe Influences of deposition time and pH on magnetic NiFe nanowires fabrication(Elsevier Science Sa, 2009) Atalay, Funda Ersoy; Kaya, Harun; Atalay, Selcuk; Tari, SueleymanIn this work, NiFe nanowires were grown into highly ordered porous anodic alumina oxide (AAO) templates by dc electrodeposition at various deposition times and pH values. During the deposition process some electrochemical bath parameters such as ion content, deposition voltage, and temperature of solution were kept constant. The morphological properties of the nanowire arrays were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the chemical composition was determined by examination of the energy dispersive X-ray (EDX) spectra, and the magnetic behavior of the arrays was determined by vibrating sample magnetometer (VSM). (C) 2008 Elsevier B.V. All rights reserved.Öğe Investigation of a weak magnetic field effect on the in vitro catalytic activity of adenosine deaminase and xanthine oxidase(General Physiol And Biophysics, 2011) Batcioglu, Kadir; Dogan, Metin; Uyumlu, Ayse B.; Satilmis, Basri; Bayri, Nevzat; Atalay, Selcuk; Demirtas, HakanThe effect of a weak magnetic field (MF) on adenosine deaminase (ADA) and xanthine oxidase (XOD) activities have been investigated. A 50 Hz uniform MF was generated, and the magnitude of the field was kept constant at 5.8 mT. The changes in ADA activity over time were significantly different in and out of the MF; MF caused a steeper decline in ADA activity compared to the situation when no MF is present. In addition, MF caused a significant increase in XOD activity. There were no significant time-related changes for either enzyme in the absence of the MF. We suggest that a weak MF affects enzymatic systems.Öğe Magnetoelastic Humidity Sensors with TiO2 Nanotube Sensing Layers(Mdpi, 2020) Atalay, Selcuk; Izgi, Tekin; Kolat, Veli Serkan; Erdemoglu, Sema; Inan, Orhan OrcunIn this study, TiO2 nanotubes (TiO2-NTs) are coated with a drop-casting method on Fe40Ni38Mo4B18 amorphous ferromagnetic ribbons and the humidity response of the prepared magnetoelastic sensors (MES) is investigated. The synthesis of TiO2-NTs is performed using a hydrothermal process. Sample characterization is carried out using X-ray diffraction and scanning electron microscopy. The results show that the sensors can measure moisture values in the range of 5% to 95% with very high precision and very low hysteresis. The humidity variation between 5% and 95% shows a change in the sensor resonance frequency of 3180 Hz, which is a significant change compared to many magnetoelastic humidity sensors developed so far.Öğe A Positive Effect of Magnetic Field on the Catalytic Activity of Immobilized L-Asparaginase: Evaluation of its Feasibility(Springer, 2023) Dik, Gamze; Ulu, Ahmet; Inan, Orhan Orcun; Atalay, Selcuk; Ates, BurhanEnzyme immobilization is an attractive strategy to improve enzyme stability, however, the activity significantly reduces after immobilization. To solve this issue, we designed a novel magnetic carrier that both enhanced enzyme activity and improved its stability. For this purpose, the magnetic nanoparticles were synthesized and L-asparaginase was immobilized physically. All materials were structurally and morphologically characterized. Besides, the biochemical properties of the immobilized enzyme were investigated and compared with the free one. Moreover, the activity of the immobilized enzyme was investigated under a weak magnetic field. The optimum pH and optimum temperature of the free and immobilized enzyme were found to be 8.5 and 45 degrees C, 7.5 and 40 degrees C, respectively. Moreover, even after 10 cycles of use, the immobilized enzyme retained 54% of its initial activity. K-m for free and the immobilized enzyme was found to be 10.37 +/- 0.5, and 7.06 +/- 2.99 mM, respectively, and V-max was found to be 138.88 +/- 2.64, and 121.95 +/- 1.07 molimin, respectively. Most importantly, the activity increased approximately 3.2-fold and 4.3-fold at 10 Hz and 20 mT, respectively. Overall, the results suggested that, if the activity of the immobilized enzyme is very low, applying a weak magnetic field may be necessary to enhance the enzyme reaction. [GRAPHICS] .Öğe A Rapid Response Humidity Sensor for Monitoring Human Respiration with TiO2-Based Nanotubes as a Sensing Layer(Springer, 2020) Atalay, Selcuk; Erdemoglu, Sema; Kolat, Veli Serkan; Izgi, Tekin; Akgeyik, Emrah; Yilmaz, Hatice Caglar; Kaya, HarunThe use of TiO2-based samples with nanotube (NT) shape for humidity sensing has been investigated. Sample characterization was carried out using x-ray diffraction analysis, scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy. x-Ray diffraction analysis showed that the nanotubes had TiO2, NaO3, and H2Ti2O5 phases. SEM revealed that the NTs had diameters ranging from 20 nm to 200 nm and very different lengths. TiO2-based nanotubes were coated using the drop-casting method onto a quartz crystal microbalance (QCM). The synthesis of TiO2-based NTs was performed using a hydrothermal process. Humidity sensing measurements showed that the resonant frequency of TiO2-based NTs deposited onto the QCM was very sensitive to humidity changes. It was also shown that the sensor could be used for respiratory monitoring purposes.Öğe Rapid synthesis and characterization of maghemite nanoparticles(Amer Scientific Publishers, 2008) Tural, Bilsen; Oezenbas, Macit; Atalay, Selcuk; Volkan, MuervetFe2O3-SiO2 nanocomposites were prepared by a sol-gel method using various evaporation surface to volume (S/V) ratios ranging from 0.03 to 0.2. The Fe2O3-SiO2 sols were gelated at various temperatures ranging from 50 degrees C to 70 degrees C, and subsequently they were calcined in air at 400 degrees C for 4 hours. The structure and the magnetic properties of the prepared Fe2O3-SiO2, nanocomposites were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), differential thermal analysis (DTA), and vibrating sample magnetometer (VSM) measurements. The gelation temperature of the Fe2O3-SiO2 sols influenced strongly the particle size and crystallinity of the maghemite nanoparticles. It was observed that the particle size of maghemite nanoparticles increased with the increasing of the gelation temperature of the sols, which may be due to the agglomeration of the maghemite particles at elevated temperatures inside the microporosity of the silica matrix during the gelation process, and the subsequent calcination of these gels at 400 degrees C resulted in the formation of large size iron oxide particles. Magnetization studies at temperatures of 10, 195, and 300 K showed superparamagnetic behavior for all the nanocomposites prepared using the evaporation surface to volume ratio (S/V) of 0.1, 0.2, 0.09, and 0.08. The saturation magnetization, Ms, values measured at 10 K were 5.5, 8.5, and 9.5 emu/g, for the samples gelated at 50, 60, and 70 degrees C, respectively. At the gelation temperature of 70 degrees C, gamma-Fe2O3 crystalline superparamagnetic nanoparticles with the particle size of 9 +/- 2 nm were formed in 12 hours for the samples prepared at the S/V ratio of 0.2.Öğe Resonance Frequency Shift of Vibrating Amorphous Ribbon via Surface Adsorption of Magnetic Fe3O4 Nanoparticles(Springer, 2023) Atalay, Selcuk; Inan, Orhan Orcun; Kolat, Veli Serkan; Kaya, Ali OnurIn this study, Fe40Ni38Mo4B18 amorphous ferromagnetic ribbon was used as a vibrating reed sensor to detect Fe3O4 magnetic nanoparticles. The sensor surface was not subjected to any treatment: the amorphous ribbon was used directly as a sensor. Nanoparticles with a diameter of 25 nm in ddH(2)O were dripped on the sensor surface at different rates. Different amounts of magnetic nanoparticles ranging from 1 to 12 mu g were dripped, and it was observed that the sensor resonance frequency decreased linearly with the mass of magnetic nanoparticles dripped. It was shown that 1 mu g MNP could be easily detected by the vibrating reed method.Öğe Structural evolution and microwave absorption properties of MnFe2O4/BaTiO3 nanoparticle systems and their composites(Springer, 2026) Atalay, Selcuk; Durmaz, Ergun; Seker, Omer FarukIn this study, MnFe2O4/BaTiO3 nanoparticle systems were systematically investigated as microwave absorbers in the X-band (8-12.4 GHz). Nanoparticles were physically mixed at different weight ratios and examined both before and after annealing at 1100 C for 3 h. The microstructural and magnetic properties were evaluated using SEM, TEM, XRD, XPS, FTIR and M-H hysteresis measurements, respectively. Structural analyses revealed that the as-mixed samples consist of coexisting MnFe2O4 and BaTiO3 phases, while annealing induces an in-situ transformation into an Mn/Ti-substituted M-type barium hexaferrite phase. This phase evolution leads to a significant increase in saturation magnetization and coercivity, indicating a transition toward harder magnetic behavior. Microwave absorption performance was evaluated using reflection loss measurements. The non-annealed 50 MnFe2O4-50 BaTiO3 composite exhibits the best absorption performance, with a minimum reflection loss (RL) of approximately - 23 dB at 10.8-11.0 GHz. In contrast, annealed samples show reduced absorption efficiency, with minimum reflection loss values in the range of - 10 to - 16 dB. These results demonstrate that enhanced magnetic hardness does not necessarily improve microwave absorption in MnFe2O4/BaTiO3-based absorbers.Öğe Structural, Magnetic, and Magnetocaloric Properties of La1-x Bi x MnO3 (x=0.01, 0.03, 0.06, 0.1, 0.2) Compounds(Springer, 2015) Kolat, Veli Serkan; Atalay, Selcuk; Izgi, Tekin; Gencer, Huseyin; Bayri, NevzatBi-doped lanthanum manganites with chemical composition of La1-x Bi (x) MnO3 (x = 0.01, 0.03, 0.06, 0.1, and 0.2) were prepared by a standard solid-state process. Magnetic and magnetocaloric properties of the samples were investigated in detail. X-ray diffraction measurement showed that the sample crystallized in the single phase of orthorhombic structure. It was found that the magnetization, Curie temperature, and the maximum value of magnetic entropy change decrease with increasing Bi content. The decrease in magnetic entropy change was attributed to the decrease in saturation magnetization and a change of the nature of the phase transition from first order to second order with increasing Bi content.Öğe Synthesis, characterization, crystallization kinetics of amorphous Fe74.5Zr8.5B17 magnetic nanoparticles, and magnetoelectric properties of Fe74.5Zr8.5B17/BaTiO3 composite(Springer, 2025) Dik, Gamze; Kaplan, Emine Busra; Ulu, Ahmet; Bayri, Nevzat; Ates, Burhan; Atalay, SelcukThis work reports the facile synthesis ofamorphous Fe74.5 Zr8.5 B17 magnetic nanoparticles (MNPs) through a simple NaBH4-assisted chemical reduction method. The obtained MNPs were characterized in terms of amorphous/crystal structure, morphology, magnetic properties, composition, and crystallization kinetics. The saturation magnetization value was determined as 57.83 emu/g. The crystallization peak temperatures (Tp) and activation energy were determined to be 467.18 degrees C and 294 kJ/mol, respectively. Additionally, the FeZrB MNPs were combined with the BaTiO3 NPs via ball milling at low speed, using a mass ratio of 30/70%, respectively and the magnetoelectric coefficient value for FeZrB/BaTiO3 composite measured at a 1 kHz AC magnetic field is approximately 8.9 mV/Oe/cm. The study outcomes may provide a platform of nanotechnology for the preparation of MNPs with adjustable properties, which will be promising for practical applications.
