Halina V. Grushevskaya; Nina G. Krylova; Igor V. Lipnevich; Taisija I. Orekhovskaja; Boris G. Shulitski
Abstract
A capacitive nanobiosensor which consists of multiwalled carbon nanotubes (MWCNTs) covered by conducting oligomer of thiophene-pyrrole derivatives was constructed and fabricated to detect the gap junction-mediated communication between living cells in a monolayer. The sensor operates on screening and ...
Read More
A capacitive nanobiosensor which consists of multiwalled carbon nanotubes (MWCNTs) covered by conducting oligomer of thiophene-pyrrole derivatives was constructed and fabricated to detect the gap junction-mediated communication between living cells in a monolayer. The sensor operates on screening and spin-dependent polarization effects in nanoheterostructures which present themselves MWCNTs decorated by organometallic complexes of high-spin Fe(II) and are fabricated by a Langmuir-Blodgett (LB) technique. The nanoheterostructures were deposited on transducer, which is an interdigital electrode system covered by a dielectric layer. As the cell monolayer density increased while the cells proliferated on the sensor surface, the sensor capacity decreased until the cell monolayer was confluent. This decrement is due to a forming network of the open gap junction channels (GJCs) in accordance with an electrochemical analysis performed. The monolayer capacity increases when adding GJC inhibitor (carbenoxolone) which leads to decrease of a number of the open GJCs. The technique has been used in real-time regime to establish some principles of menadione-mediated GJC-network fine-tuning. Menadione causes Ca 2+ -dependent GJ channels opening/closing.
Rajababu Chintaparty; N. Ramamanohar Reddy
Abstract
Zirconium Oxide (zirconia) particles were prepared through hydrothermal technique by using zirconium oxychloride (ZrOCl2.8H2O) and zirconyl nitrate (ZrO (NO3)2.H2O) as precursors. The structural characterization as prepared samples were confirmed by X-ray powder diffraction (XRD) and showed monoclinic ...
Read More
Zirconium Oxide (zirconia) particles were prepared through hydrothermal technique by using zirconium oxychloride (ZrOCl2.8H2O) and zirconyl nitrate (ZrO (NO3)2.H2O) as precursors. The structural characterization as prepared samples were confirmed by X-ray powder diffraction (XRD) and showed monoclinic phase. Further, surface morphology of synthesized zirconia particles were confirmed by scanning electron microscopy (SEM). The energy band gap of synthesized samples was evaluated from UV-vis absorption spectra. The frequency dependence of dielectric constant and dielectric loss of the samples were investigated at room temperature. Zirconium oxychloride was found to be better precursor for obtaining ZrO2 with a higher dielectric constant than Zirconyl nitrate under the same synthesis conditions.
B. C. Sutar; Piyush R. Das; R. N. P. Choudhary
Abstract
Lead-free polycrystalline material Sr(Bi0.5V0.5)O3 was prepared using a high- temperature solid state reaction technique (calcinations and sintering temperature =850 and 950 o C, respectively) using high-purity ingredients. The formation of the material in the monoclinic crystal structure was confirmed ...
Read More
Lead-free polycrystalline material Sr(Bi0.5V0.5)O3 was prepared using a high- temperature solid state reaction technique (calcinations and sintering temperature =850 and 950 o C, respectively) using high-purity ingredients. The formation of the material in the monoclinic crystal structure was confirmed by preliminary X-ray structural analysis with room temperature data.The nature of microstructure obtained by scanning electron microscopy (SEM) shows that the compound has well defined grains which are uniformly distributed throughout the surface of the sample. Detailed studies of dielectric and impedance properties of the material carried out in the frequency range of 1 kHz –1MHz at different temperatures (30 0 C to 455 0 C) have provided many interesting properties. Detailed studies of dielectric properties of the compound showed an existence of diffus e phase transition around 258 0 C. The temperature dependence of electrical parameters (impedance, modulus etc.) of the material exhibits a strong correlation of its microstructure with the electrical parameters. The negative temperature coefficient of resistance (NTCR) behavior also was observed in the material. The complex electric modulus analysis indicates the presence of hopping conduction mechanism in the system with non-exponential type of conductivity relaxation. The nature of variation of dc conductivity with temperature confirms the Arrhenius behavior of the material. The ac conductivity spectra show a typical signature of an ionic conducting system, and are found to obey Jonscher’s universal power law.
Piyush R. Das; B. Pati; B.C. Sutar; R.N.P. Choudhury
Abstract
Complex impedance analysis of new tungsten bronze ferroelectric vanadates, Na2Pb2R2W2Ti4V4O30 (R = Gd, Eu), was carried out on samples prepared relatively at low temperature using a mixed-oxide technique. The formation of the materials under the reported conditions has been confirmed by an X-ray diffraction ...
Read More
Complex impedance analysis of new tungsten bronze ferroelectric vanadates, Na2Pb2R2W2Ti4V4O30 (R = Gd, Eu), was carried out on samples prepared relatively at low temperature using a mixed-oxide technique. The formation of the materials under the reported conditions has been confirmed by an X-ray diffraction technique. A preliminary structural analysis exhibits orthorhombic crystal structure of the materials at room temperature. The electrical properties of the materials have been studied using ac impedance spectroscopy technique. Detailed studies of impedance and related parameters exhibit that the electrical properties of the materials are strongly dependent on temperature, and bear a good correlation with their microstructures. The temperature dependence of electrical relaxation phenomenon in the materials has been observed. The bulk resistance, evaluated from complex impedance spectra, is found to decrease with rise in temperature, exhibiting a typical negative temperature co-efficient of resistance (NTCR) – type behavior similar to that of semiconductors. A small contribution of grain boundary effect was also observed. The complex electric modulus analysis indicates the possibility of hopping conduction mechanism in the system with non-exponential type of conductivity relaxation. The ac conductivity spectra exhibit a typical signature of an ionic conducting system, and are found to obey Jonscher’s universal power law.