Cancelation of LNA distortions in in-band full-duplex systems

International audienceIn‐band full‐duplex (FD) transceiver has been recently proposed to double the channel efficiency. The main challenge of such FD transceiver consists in achieving an efficient self‐interference cancelation. This fact is prevented by receiver imperfections such as the oscillator phase noise, the analog‐to‐digital converter noise, and the nonlinear distortion (NLD) of the low‐noise amplifier (LNA). This paper deals with the mitigation of the NLD of the receiver's LNA by proposing a new FD transceiver architecture. Based on the fact that the NLD coefficients are changing slowly over time, then the period between two successive estimations of the NLD coefficients may be relatively long. Motivated by this fact, a new wire connection is introduced between the transmitting circuit and the receiving one in order to neglect the wireless channel effects when estimating the NLD coefficients. If the estimation of the NLD coefficients is required, then the transmitter stops the wireless transmission and sends a sequence to the receiver via the wire channel. This procedure does not affect the throughput rate since it is repeated every several frames due to the slow time‐variation of the NLD coefficients. The estimated coefficients are used to attenuate the effects of NLD at the receiver's side, where an auxiliary chain is introduced to act as reference to the receiver's ordinary chain. As a proof of the concept, intensive simulations have been done using realistic data parameters. Our numerical results corroborate the efficiency of the proposed architecture, where the NLD of LNA is highly attenuated leading to an efficient self‐interference cancelation

Mitigation of sodium chloride toxicity in Solanum lycopersicum L. by supplementation of jasmonic acid and nitric oxide

We investigated the effects of exogenous application of jasmonic acid (JA) and nitric oxide (NO) on growth, antioxidant metabolism, physio-biochemical attributes and metabolite accumulation, in tomato (Solanum lycopersicum L.) plants exposed to salt stress. Treating the plants with NaCl (200 mM) resulted in considerable growth inhibition in terms of biomass, relative water content, and chlorophyll content, all of which were significantly improved upon application of JA and NO under both normal and NaCl-stress treatments. Salt treatment particularly 200 mM NaCl caused an apparent increase in electrolyte leakage, lipid peroxidation, and hydrogen peroxide production, which were reduced by exogenous application of JA and NO. Salt treatment triggered the induction of antioxidant system by enhancing the activities of antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR). Application of JA and NO separately as well as in combination caused a significant improvement in activities of SOD, CAT, APX, and GR activities. JA and NO either applied individually or in combination boosted the flavonoid, proline and glycine betaine synthesis under NaCl treatments. In conclusion, the exogenous application of JA and NO protected tomato plants from NaCl-induced damage by up-regulating the antioxidant metabolism, osmolyte synthesis, and metabolite accumulation

Screening of quorum sensing and biofilm inhibitors among pseudomonas aeruginosa clinical isolates

Quorum sensing (QS) is a process that enables bacteria to communicate using secreted small pheromone-like signaling molecules called autoinducers (AIs). This process enables a population of bacteria to regulate gene expression collectively. These quorum sensing systems regulates biofilm formation, virulence factors expression, bioluminescence, motility patterns, exopolysaccharide production, antifungal or antibiotic production, endoglucanase production, pigmentation, competence, plasmid conjugal transfer and cross-signaling between strains and species. P. aeruginosa is an important and very dangerous opportunistic pathogen causing many fatal infections in patients with serious medical conditions. P. aeruginosa is associated with nosocomial infections mainly in immunocompromised patients, and it is rated the third-most-common microorganism associated with hospital-acquired infections representing about 10-15% of nosocomial infections recorded globally. Moreover, qRT-PCR revealed a significant reduction in expression of quorum sensing genes in virulence inhibitors-treated P. aeruginosa in comparison with untreated bacteria. Virulence inhibitors could play a role in reduction of Pseudomonas quorum sensing-dependent virulence factors production such as biofilm production, and therefore affect its pathogenesis in the host

Upregulation of antioxidant and glyoxalase systems mitigates NaCl stress in Brassica juncea by supplementation of zinc and calcium

Possible involvement of calcium (Ca) and zinc (Zn) in mitigation of salt (NaCl) stress-induced oxidative damage in Brassica juncea was investigated. Salt stress (200 mM NaCl) reduced leaf pigment synthesis and some key photosynthetic attributes including stomatal conductance and internal CO2 concentration. Exogenous application of Ca and Zn resulted in enhanced growth possibly by induction of the antioxidant defense system, resulting in improved redox state thereby favoring growth improvement. Proline accumulation (3.39-fold) was stimulated by exogenous application of Zn and Ca causing improvement in growth through enhancement in relative water content (78.46%) and increased flavonoid accumulation (86.19%). NaCl stress enhanced the hydrogen peroxide (H2O2), malondialdehyde and methylglyoxal content by 3-fold, 1.51-fold, and 2.98-fold, respectively, however, supplementation of Ca and Zn individually as well as in combination reduced the accumulation to an appreciable level. Ca and Zn treatment helped Brassica juncea plants to strengthen the antioxidant system and glyoxalase system and also enzymes of ascorbate-glutathione (AsA-Glu) cycle for better protection to membranes from reactive oxygen species. Moreover, Ca and Zn supplementation reduced the salt-induced damage by maintaining Na/K ratio through improved K uptake

Zinc application mitigates the adverse effects of NaCl stress on mustard [Brassica juncea (L.) Czern & Coss] through modulating compatible organic solutes, antioxidant enzymes, and flavonoid content

This study examined the protective effect of Zn on salt-stressed Brassica juncea plants using some key morphological and biochemical attributes at different developmental stages (30, 60, and 90 days after treatment [DAT]). Salt stress (200 mM) caused suppression in plant height, root length, and dry weight by 58.35%, 41.15%, and 53.33%, respectively, at 90 DAT, but Zn application improved these variables by 15.52%, 16.59%, and 11.45%, respectively. Furthermore, 200 mM NaCl decreased total chlorophyll by 45.32% and relative water content by 27.62% at 90 DAT, whereas Zn application compensated the decrease in the levels of both variables. NaCl (200 mM) increased H2O2, malondialdehyde, and electrolyte leakage by 70.48%, 35.25%, and 68.39%, respectively, at 90 DAT, but Zn supplementation appreciably reduced these variables. Except for catalase, enzymatic antioxidant activity increased under NaCl stress. Zn application with salt further increased the activities of superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, and glutathione-S-transferase by 33.51%, 9.21%, 10.98%, 17.46%, and 12.87%, respectively, at 90 DAT. At 90 DAT, salt stress increased flavonoids by 24.88%, and Zn supply by a further 7.68%. Overall, Zn mitigated the adverse effects of salt stress through osmotic adjustment, as well as by modulating the oxidative defense system and flavonoid contents

Potential of exogenously sourced kinetin in protecting Solanum lycopersicum from NaCl-induced oxidative stress through up-regulation of the antioxidant system, ascorbate-glutathione cycle and glyoxalase system.

The protective role of exogenously applied kinetin (10 μM KN, a cytokinin) against the adverse effects caused by NaCl-induced (150 mM) stress in Solanum lycopersicum was investigated. Application of KN significantly enhanced growth and biomass production of normally grown plants (non-stressed) and also mitigated the adverse effect of NaCl on stressed plants to a considerable extent. Among the examined parameters, chlorophyll and carotenoid contents, photosynthetic parameters, components of the antioxidant system (both enzymatic and non-enzymatic), osmotica accumulation, and mineral uptake exhibited a significant increase following the application of KN. Furthermore, KN application reduced the generation of reactive free radical hydrogen peroxide, coupled with a significant reduction in lipid peroxidation and an increase in membrane stability. The activities of antioxidant enzymes, and glyoxylase system were found to be promoted in plants exposed to NaCl, and the activities were further promoted by KN application, thereby protecting S. lycopersicum plants against NaCl-induced oxidative damage. Further strengthening of the antioxidant system in KN supplied plants was ascribed to regulation of ascorbate-glutathione cycle, phenols and flavonoids in them. The levels of proline and glycine betaine increased considerably in KN-treated plants, thereby maintaining relative water content. Moreover, exogenous KN application reduced the inhibitory effects of NaCl on K+ and Ca2+ uptake, which resulted in a considerable reduction in tissue Na+/K+ ratio