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    FT-IR spectroscopic investigation of some Hofmann type complexes: M(2-(1-Cyclohexenyl)ethylamine)2Ni(CN)4 (M = Ni, Co)
    (Elsevier Science Bv, 2008) Izgi, Tekin; Parlak, Cemal; Aytekin, Tuerkay; Senyel, Mustafa
    New Hofmann type complexes in the form of M(CyHEA)(2)Ni(CN)(4) (where CyHEA = 2-(1-cyclohexenyl)ethylamine; M = Ni or Co) have been prepared in powder form and their infrared spectra have been reported in the range of 4000-400 cm(-1). The thermal behaviour of these complexes has been investigated by differential thermal analysis (DTA) and thermo-gravimetric analysis (TGA). The results suggest that these compounds are similar in structure to Hofmann type complexes and their structures consist of polymeric layers vertical bar M-Ni(CN)(4)vertical bar(infinity) with the CyHEA molecule bound to the metal atom (M). (C) 2008 Published by Elsevier B.V.
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    Magnetic-propelled Fe3O4-chitosan carriers enhance l-asparaginase catalytic activity: a promising strategy for enzyme immobilization
    (Royal Soc Chemistry, 2018) Ates, Burhan; Ulu, Ahmet; Koytepe, Suleyman; Ali Noma, Samir Abbas; Kolat, Veli Serkan; Izgi, Tekin
    Magnetic-propelled carriers comprising magnetic Fe3O4-chitosan nanoparticles were immobilized with l-asparaginase (l-ASNase). The enzyme displayed enhanced catalytic activity in a weak magnetic field, and thermal and pH stabilities. The conjugated l-ASNase presented higher thermostability and wider range of pH stability in comparison with those of free l-ASNase. Moreover, the reusability of conjugated l-ASNase significantly improved after immobilization and it retained 60.5% of its initial activity after undergoing 16 cycles. The conjugated l-ASNase maintained more than 50% and 48% initial activity after 4 weeks of storage at 4 degrees C and room temperature, respectively. Furthermore, we reveal that the activity of conjugated l-ASNase onto magnetic Fe3O4-chitosan particles increased by about 3-fold in the weak magnetic field at certain frequencies and flux density compared with that of free l-ASNase. Considering these excellent attributes, the magnetic-propelled mechanism in the transporting and activation of l-ASNase can be used by enhancing the catalytic activity, stability, and efficiency in vital implications for medicinal biotechnology.
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    Magnetoelastic Humidity Sensors with TiO2 Nanotube Sensing Layers
    (Mdpi, 2020) Atalay, Selcuk; Izgi, Tekin; Kolat, Veli Serkan; Erdemoglu, Sema; Inan, Orhan Orcun
    In 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.
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    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, Harun
    The 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.
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    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, Nevzat
    Bi-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.
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    Vibrational spectroscopic investigations of some Hofmann-Td-type complexes: Ni(2-(1-cyclohexenyl)ethylamine)2M(CN)4 (M = Cd or Hg)
    (Pergamon-Elsevier Science Ltd, 2010) Izgi, Tekin; Parlak, Cemal; Senyel, Mustafa
    New Hofmann-T-d- type complexes in the form of Ni(CyHEA)(2)M(CN)(4) (where CyHEA = 2-(1-cyclohexenyl)ethylamine and M = Cd or Hg) have been prepared in powder form and their infrared (4000-100 cm(-1)) and Raman (2800-1650 cm(-1)) spectra have been reported. The thermal behaviour of these complexes has been investigated by differential thermal analysis (DTA) and thermo-gravimetric analysis (TGA). The results suggest that these compounds are similar in structure to the Hofmann-T-d-type complexes. (C) 2009 Elsevier B.V. All rights reserved.
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    Vibrational spectroscopic study on some Hofmann type clathrates: M(2-(1-cyclohexenyl)ethylamine)2Ni(CN)4•2benzene (M = Ni and Cd)
    (Pergamon-Elsevier Science Ltd, 2011) Izgi, Tekin; Parlak, Cemal; Senyel, Mustafa
    New Hofmann type benzene clathrates in the form of M(CyHEA)(2)Ni(CN)(4)center dot 2benzene (where CyHEA= 2-(1-cyclohexenyl)ethylamine and M=Ni or Cd) have been prepared in powder form and FT-IR and Raman spectra have been reported. The results suggest that title compounds are similar in structure to Hofmann type clathrates and their structures consist of polymeric layers of vertical bar M-Ni(CN)(4)vertical bar(infinity) with the CyHEA molecule bounded to the metal atoms (M). (C) 2011 Published by Elsevier B.V.