Primary thermometry triad at 6 mK in mesoscopic circuits

Quantum physics emerge and develop as temperature is reduced. Although mesoscopic electrical circuits constitute an outstanding platform to explore quantum behavior, the challenge in cooling the electrons impedes their potential. The strong coupling of such micrometer-scale devices with the measurement lines, combined with the weak coupling to the substrate, makes them extremely difficult to thermalize below 10 mK and imposes in-situ thermometers. Here we demonstrate electronic quantum transport at 6 mK in micrometer-scale mesoscopic circuits. The thermometry methods are established by the comparison of three in-situ primary thermometers, each involving a different underlying physics. The employed combination of quantum shot noise, quantum back-action of a resistive circuit and conductance oscillations of a single-electron transistor covers a remarkably broad spectrum of mesoscopic phenomena. The experiment, performed in vacuum using a standard cryogen-free dilution refrigerator, paves the way toward the sub-millikelvin range with additional thermalization and refrigeration techniques.Comment: Article and Supplementar

Circuit Quantum Simulation of a Tomonaga-Luttinger Liquid with an Impurity

The Tomonaga-Luttinger liquid (TLL) concept is believed to generically describe the strongly-correlated physics of one-dimensional systems at low temperatures. A hallmark signature in 1D conductors is the quantum phase transition between metallic and insulating states induced by a single impurity. However, this transition impedes experimental explorations of real-world TLLs. Furthermore, its theoretical treatment, explaining the universal energy rescaling of the conductance at low temperatures, has so far been achieved exactly only for specific interaction strengths. Quantum simulation can provide a powerful workaround. Here, a hybrid metal-semiconductor dissipative quantum circuit is shown to implement the analogue of a TLL of adjustable electronic interactions comprising a single, fully tunable scattering impurity. Measurements reveal the renormalization group `beta-function' for the conductance that completely determines the TLL universal crossover to an insulating state upon cooling. Moreover, the characteristic scaling energy locating at a given temperature the position within this conductance renormalization flow is established over nine decades versus circuit parameters, and the out-of-equilibrium regime is explored. With the quantum simulator quality demonstrated from the precise parameter-free validation of existing and novel TLL predictions, quantum simulation is achieved in a strong sense, by elucidating interaction regimes which resist theoretical solutions.Comment: To be published in Phys. Rev.

Metamaterial superlenses operating at visible wavelength for imaging applications

© 2018 The Authors. Published by Nature. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1038/s41598-018-33572-yIn this paper, a novel design for a metamaterial lens (superlens) based on a Photonic Crystal (PC) operating at visible wavelengths is reported. The proposed superlens consist of a gallium phosphide (GaP) dielectric slab waveguide with a hexagonal array of silver rods embedded within the GaP dielectric. In-house 2DFDTD numerical method is used to design and optimize the proposed superlens. Several superlenses are designed and integrated within a same dielectric platform, promoting the proof-of-concept (POC) of possible construction of an array of superlenses (or sub-lenses to create an M-Lens) for light field imaging applications. It is shown that the concavity of the superlens and positioning of each sub-lens within the array strongly affects the performances of the image in terms of resolution. Defects and various geometrical shapes are introduced to construct and optimize the proposed superlenses and increase the quality of the image resolution. It is shown that the orientation of the active region (ellipse) along x and y axis has tremendous influence on the quality of image resolution. In order to investigate the performance characteristics of the superlenses, transmitted power is calculated using 2D FDTD for image projections at various distances (in x and y plane). It is also shown, how the proposed superlens structures could be fabricated using standard micro fabrication techniques such as electron beam lithography, inductively coupled Reactive ion etching, and glancing angle evaporation methods. To the best of our knowledge, these are the first reported POC of superlenses, integrated in a monolithic platform suitable for high imaging resolution that can be used for light field imaging applications at visible wavelength. The proposed superlenses (integrated in a single platform M-Lens) will have tremendous impact on imaging applications

Crystal structure, optical properties, vibrational, thermal and biological study of a new polymeric Cd(II) hybrid material

International audienceThis paper describes a new polymeric one-dimensional chlorocadmate(II) compound synthesized with a slow evaporation method. The crystal structure was determined by single-crystal X-ray diffraction. It crystallizes in the Tetragonal system, P 4/n space group, with the following room temperature cell parameters: a = 15.9451(14) Å, c = 11.1726(10) Å with Z = 2 and V = 2840.6(6) Å3. The examination of the structure shows that the anionic part is formed of covalent polymeric chains of (CdCl5)n and isolated CdCl4 tetrahedrons. Hirshfeld surface analysis was used to verify the contributions of the different intermolecular interactions. UV–Vis measurements were employed to figure out the optical behavior of the reported crystal. The vibrational properties were investigated through IR spectroscopy. TG-DSC thermal analysis revealed that the compound remains stable up to 130 °C. For the in vitro antibacterial activity test, results showed that there is no significant difference (p ≥ 0.05) between the inhibition zones caused by the compound and the amine. However, DPPH and ABTS tests showed that the free radical scavenging activity of the tested compound was higher than the amine

Arabidopsis thaliana tolerates iron deficiency more than Thellungiella salsuginea by inducing metabolic changes at the root level

Several studies have used A. thaliana as a model to identify the physiological and molecular mechanisms underlying iron deficiency tolerance in plants. Here, Arabidopsis thaliana and Thellungiella salsuginea were used to investigate the differential responses to iron deficiency of these two species. Plants were cultivated in hydroponic medium containing 5 or 0 μM Fe, for 10 days. Results showed that rosette biomass was more reduced in T. salsuginea than in A. thaliana when grown on Fe-deficient medium. As a marker for iron deficiency tolerance, the induction of ferric chelate reductase (FCR) and phosphoenolpyruvate carboxylase (PEPC) activities was observed only in A. thaliana roots. In addition, we found that the accumulation of phenolic acids in roots of N1438 ecotype of A. thaliana was stimulated by Fe deficiency. Furthermore, an increase of flavonoids content in the root and exudates was observed under Fe-deficiency in this ecotype. Unlike other abiotic stresses, it appears that iron deficiency effects were more pronounced in Thellungiella than in Arabidopsis. The higher tolerance of the Arabidopsis plant to iron deficiency may be due to the metabolic changes occurring in the roots

Changes in the antioxidative systems of Ocimum basilicum L. (cv. Fine) under different sodium salts

The effects of different sodium salts on some physiological parameters and antioxidant responses were investigated in a medicinal and aromatic plant, Ocimum basilicum L. (cultivar Fine). Plants were subjected to an equimolar concentration of Na2SO4 (25 mM) and NaCl (50 mM) for 15 and 30 days. Growth, oxidative stress parameters [electrolyte leakage, peroxidation, and hydrogen peroxide (H2O2) concentration], antioxidant enzyme activities [ascorbate peroxidase (APX, EC 1.11.1.11), glutathione reductase (GR, EC 1.6.4.2), and peroxidases (POD, EC 1.11.1.7)], as well as antioxidant molecules [ascorbate and glutathione] were determined. The two salts affected leaf growth rates to the same extent, after 15 or 30 days of treatment, indicating a similar effect of Na2SO4 and NaCl salinity on growth, even if different (enzymatic and non-enzymatic) antioxidant mechanisms were involved in H2O2 detoxification. However, under both salts, the efficiency of the antioxidant metabolism seemed to be sufficient to avoid the deleterious effects of reactive oxygen species (ROS). Indeed, both ion leakage and peroxidation did not change under either Na2SO4 or NaCl salinity. As a whole, these data suggest that a cooperative process between the antioxidant systems is important for the tolerance of Ocimum basilicum L., cv. Fine to Na2SO4 and NaCl salinity

Antioxidative responses of Ocimum basilicum to sodium chloride or sodium sulphate salinization

Soils and ground water in nature are dominated by chloride and sulphate salts. There have been several studies concerning NaCl salinity, however, little is known about the Na2SO4 one. The effects on antioxidative activities of chloride or sodium sulphate in terms of the same Naþ equivalents (25 mM Na2SO4 and 50 mM NaCl) were studied on 30 day-old plants of Ocimum basilicum L., variety Genovese subjected to 15 and 30 days of treatment. Growth, thiobarbituric acid reactive substances (TBARS), relative ion leakage ratio (RLR), hydrogen peroxide (H2O2), ascorbate and glutathione contents as well as the activities of ascorbate peroxidase (APX, EC 1.11.1.11); glutathione reductase (GR, EC 1.6.4.2) and peroxidases (POD, EC 1.11.1.7) were determined. In leaves, growth was more depressed by 25 mM Na2SO4 than 50 mM NaCl. The higher sensitivity of basil to Na2SO4 was associated with an enhanced accumulation of H2O2, an inhibition of APX, GR and POD activities (with the exception of POD under the 30-day-treatment) and a lower regeneration of reduced ascorbate (AsA) and reduced glutathione (GSH). However, the changes in the antioxidant metabolism were enough to limit oxidative damage, explaining the fact that RLR and TBARS levels were unchanged under both Na2SO4 and NaCl treatment. Moreover, for both salts the 30-day-treatment reduced H2O2 accumulation, unchanged RLR and TBARS levels, and enhanced the levels of antioxidants and antioxidative enzymes, thus achieving an adaptation mechanism against reactive oxygen species

Effects of Heavy Metals on Growth and Bioaccumulation of the Annual Halophytes Atriplex Hortensis and A. Rosea

Abstract: Heavy metals such Zn, Pb, Cu and Cd can cause a non-degradable pollution in numerous sites in France as well as in Tunisia, or elsewhere. This pollution resulting from various human polluting activities, related to industry or mining, is often diffuse in soils. Vegetation can play an important role in decontaminating these soils, their rehabilitation, and making their environment safer. For a better understanding of metal reactivity, a review of general knowledge concerning this kind of polluting metals and plant tolerance mechanisms is presented. A study was also conducted on the accumulation of the following metals: Cd, Cu, Zn, Pb and Ni, in their localisation in plant tissues and their induced toxic effects. The most general visible, but nonspecific symptom of heavy metal stress is growth inhibition, which has been investigated in many plants, including Atriplex. A cultivation of annual Atriplex plants was conducted according to hydroponic experimental design. The experimental approach consisted of hydroponic cultures using simplified medium represented by a nutritive solution. Results showed that plant final biomass, leaf area and metal accumulation, all varied with the metals level of toxicity and the plant species considered. Hence, the plants of the three annual arroach species or varieties used, all showed an intermediate level of tolerance according to the imposed treatments. Metal induces a number of physiological changes, such as growth inhibition, a significant reduction in biomass production was observed in metal treated plants compared with the control plants. The bioaccumulation factor decreased at the highest metal level, the low transfer of metal from solution to above-ground organs at higher solution metal concentrations indicates an exclusion mechanism. Trace element accumulation in shoots and the bioconcentration factors were proportional to the initial concentration of individual metals in the growth medium and the duration of exposure. Annual orach : A. hortensis seem to have a good capability for tolerance and phytostabilisation areas containing heavy metals