The differential dielectrometer was designed to measure small differences in complex permittivity (CP) of two high loss liquids at frequency 32.82 GHz. The measurements are fully computer-aided with the exception of liquids filling and draining in the measurement cells. The time of one measurement cycle does not exceed 3 min. The dielectrometer is easy-to-work and can be used under the conditions of scientific and industrial physical–chemical laboratories. The sensitivity of the difference in the phase coefficients of the electromagnetic waves propagated in the measurement cells is better than 0.05% and that of the attenuation coefficient is of the order of 0.2%. The dielectrometer contains two measurement cells that are dielectric quartz cylinders surrounded by high loss liquids. We developed the CP calculation algorithm using the known CP of the reference liquid and the difference coefficients of complex wave propagation in the cells. The origins of the measurement errors are studied in detail and recommendations were made to avoid some of them. The dielectrometer can be used to express the identification of wine and must authenticity by means of their CP values. The CP measurement results for solutions of some substances that make wine and must composition are obtained. The possibility of using the dielectrometer for the detection of added water in wines or musts is shown.
In-plane surface Ka-band microwave impedance of optimally doped single crystals of the Fe-based superconductor Ba(Fe 0.926 Co 0.074 ) 2 As 2 (T c = 22.8K) was measured. Sensitive sapphire disk quasi-optical resonator with high-Tc cuprate conducting endplates was developed specially for Fe-pnictide superconductors. It allowed finding temperature variation of London penetration depth in a form of power law, namely (T) T n with n = 2.8 from low temperatures up to at least 0.6T c consisted with radio-frequency measurements. This exponent points towards nodeless state with pairbreaking scattering, which can support one of the extended s-pairing symmetries. The dependence (T) at low temperatures is well described by one superconducting small-gap (0.75 in kT c units, where k is Boltzman coefficient) exponential dependence.The discovery of superconductivity in Fe-based compounds [1] stimulated tremendous efforts to establish their physical properties. Fe-based materials are similar to cuprate high-Tc superconductors, for which the mechanism of superconductivity still remains a mystery, although the symmetry of their energy gap was identified [2]. In Fe-based compounds the gap structure, particularly the presence or absence of nodes, is still a controversial issue despite the large number of the published works (see e.g. [3-7] and references therein). So far, full spectrum of possible gap structures, nodeless and nodal, single and multivalued, constant and sign -changing, has been suggested for Fe-based superconductors [2-9].
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.