Electrodynamics of quasi-two-dimensional BEDT-TTF charge transfer salts

We consider the millimeter-wave electrodynamics specific to quasi-two-dimensional conductors and superconductors based on the organic donor molecule BEDT-TTF. Using realistic physical parameters, we examine the current polarizations that result for different oscillating (GHz) electric and magnetic field polarizations. We show that, in general, it is possible to discriminate between effects (dissipation and dispersion) due to in-plane and interlayer ac currents. However, we also show that it is not possible to selectively probe any single component of the in-plane conductivity tensor, and that excitation of interlayer currents is strongly influenced by the sample geometry and the electromagnetic field polarization.Comment: 5 pages including 3 figures Minor correction to figure

Occurrence of nitric oxide synthase in Megoura viciae Buckton (Homoptera, Aphididae): an histochemical and immunohistochemical localisation

Nitric oxide (NO) is known to be involved in many physiological reactions of insects. We analysed NOS localisation in aphids of the species Megoura viciae by means of histochemical reaction for the NADPH-diaphorase activity and immunohistochemical methods for uNOS, nNOS and iNOS. The obtained data provided a complex and peculiar pattern of NOS distribution in cells and tissue of M. viciae.The histochemical reaction for NADPH-diaphorase was an indicative, but not exact marker of NOS localisation in aphids. The use of anti uNOS antiserum (frequently applied in insects) was of limited value in our specimens, whereas more satisfactory results were obtained with anti nNOS and iNOS antisera of human origin. The results of Western blot analysis confirmed the immunohistochemical ones, showing an aphid protein that reacted strongly with the polyclonal antibody anti-iNOS and anti-nNOS while a similar protein band was weakly immunoreactive with the polyclonal antibody anti-uNOS. Our results suggest that NO, prevalently synthesised by calcium/calmodulin-dependent isoform, plays important physiological roles both in adult and embryological stages of aphids. The data of principal interest was NOS presence in bacteriocytes, cells that host symbiotic prokaryotes belonging to the species Buchnera aphidicola, and in nuclei of adipocytes and gut cells

Quantum melting of the quasi-two-dimensional vortex lattice in kappa-(ET)2Cu(NCS)2

We report torque magnetization measurements in regions of the mixed state phase diagram (${\bf B}\sim\mu_o{\bf H}_{c2}$ and T$_c$/$10^3$) of the organic superconductor $\kappa-$(ET)$_2$Cu(NCS)$_2$ where quantum fluctuations are expected to dominate thermal effects. Over most of the field range below the irreversibility line (${\bf B}_{irr}$), magneto-thermal instabilities are observed in the form of flux jumps. The abrupt cessation of these instabilities just below ${\bf B}_{irr}$ indicates a quantum melting transition from a quasi-two-dimensional vortex lattice phase to a quantum liquid phase.Comment: 8 pages (inc. Figs), accepted for publication in Phys. Rev. Let

Spatio-temporal variations of macrobenthic fauna in Lake Nasser khors, Egypt

AbstractSpatial and temporal variations of macrobenthic fauna in Lake Nasser khors, were studied at four subsequent seasons during 2013. Khor Tushka West recorded the highest average number (597Org./m2). It was decreased at khor Kursku (112Org./m2) and Kalabsha (105Org./m2) while it reached the lowest at khor Wadi Abyad (65Org./m2). The highest average number was recorded during spring (447Org./m2). It decreased during winter (174Org./m2) and summer (151Org./m2), then reached the lowest during autumn (107Org./m2). Annelida, Arthropoda and Mollusca were the most dominant groups in the lake during the study being 72.65%, 26.09% and 1.35%, respectively. The highest number of species (16) was observed at khor Kalabsha. This may be due to its nature of sandy bottom. Biological indices showed high richness values of all the studies khors except khor Tushka West.These low values of indices may be due to the dominance of Annelids species especially, Limnodrilus spp. and Branchiura sowerbyi. There is a positive correlation between these species and total annelids with all physico-chemical parameters. The analysis of variance between the different khors based on the main macrobenthic groups showed a highly significant value (p<0.001)

Instrumentation for Millimeter-wave Magnetoelectrodynamic Investigations of Low-Dimensional Conductors and Superconductors

We describe instrumentation for conducting high sensitivity millimeter-wave cavity perturbation measurements over a broad frequency range (40-200 GHz) and in the presence of strong magnetic fields (up to 33 tesla). A Millimeter-wave Vector Network Analyzer (MVNA) acts as a continuously tunable microwave source and phase sensitive detector (8-350 GHz), enabling simultaneous measurements of the complex cavity parameters (resonance frequency and Q-value) at a rapid repetition rate (approx. 10 kHz). We discuss the principal of operation of the MVNA and the construction of a probe for coupling the MVNA to various cylindrical resonator configurations which can easily be inserted into a high field magnet cryostat. We also present several experimental results which demonstrate the potential of the instrument for studies of low-dimensional conducting systems.Comment: 20 pages including fig