Switching the sign of Josephson current through Aharonov-Bohm interferometry

We investigate the DC Josephson effect in a superconductor-normal metal-superconductor junction where the normal region consists of a ballistic ring. We show that a fully controllable $\pi$-junction can be realized through the electro-magnetostatic Aharonov-Bohm effect in the ring. The sign and the magnitude of the supercurrent can be tuned by varying the magnetic flux and the gate voltage applied to one arm, around suitable values. The implementation in a realistic set-up is discussed.Comment: 4 pages, 3 figure

Device for dispersal of micrometer- and submicrometer-sized particles in vaccum

A simple, versatile device for dispersing micrometer‐ and submicrometer-sized particles in vacuum is described. The source allows control of particle size (0.5 μm≤l≤200 μm) and particle flux density up to roughly 107 cm−2 s−1. Several types of microparticles were successfully dispersed

Enhancing sustainability by improving plant salt tolerance through macro-and micro-algal biostimulants

Algal biomass, extracts, or derivatives have long been considered a valuable material to bring benefits to humans and cultivated plants. In the last decades, it became evident that algal formulations can induce multiple effects on crops (including an increase in biomass, yield, and quality), and that algal extracts contain a series of bioactive compounds and signaling molecules, in addition to mineral and organic nutrients. The need to reduce the non-renewable chemical input in agriculture has recently prompted an increase in the use of algal extracts as a plant biostimulant, also because of their ability to promote plant growth in suboptimal conditions such as saline environments is beneficial. In this article, we discuss some research areas that are critical for the implementation in agriculture of macro-and microalgae extracts as plant biostimulants. Specifically, we provide an overview of current knowledge and achievements about extraction methods, compositions, and action mechanisms of algal extracts, focusing on salt-stress tolerance. We also outline current limitations and possible research avenues. We conclude that the comparison and the integration of knowledge on the molecular and physiological response of plants to salt and to algal extracts should also guide the extraction procedures and application methods. The effects of algal biostimulants have been mainly investigated from an applied perspective, and the exploitation of different scientific disciplines is still much needed for the development of new sustainable strategies to increase crop tolerance to salt stress

Flow regimes study within the Strait of Gibraltar using a high-performance numerical model

A three-dimensional sigma coordinate free-surface high-performance model is used to investigate the flow regimes within the Strait of Gibraltar. High performances are achieved through a directive-based, MPI-like, parallelization of the code, obtained using SMS tool. The model makes use of a coastal-following, curvilinear orthogonal grid, that includes the Gulf of Cadiz and the Alboran Sea, reaching very high resolution in the Strait. Four experiments with different initial salinity conditions representing the present and possible future climate conditions over the Mediterranean basin have been performed. Model results, analysed by means of the three-layer composite Froude number theory, have shown two different possible regimes within the strait; for the present climate condition the strait is subjected to a sub-maximal regimewhilefor possible future climate conditions a maximal regime can be reached

Anthocyanins are Key Regulators of Drought Stress Tolerance in Tobacco

Abiotic stresses will be one of the major challenges for worldwide food supply in the near future. Therefore, it is important to understand the physiological mechanisms that mediate plant responses to abiotic stresses. When subjected to UV, salinity or drought stress, plants accumulate specialized metabolites that are often correlated with their ability to cope with the stress. Among them, anthocyanins are the most studied intermediates of the phenylpropanoid pathway. However, their role in plant response to abiotic stresses is still under discussion. To better understand the effects of anthocyanins on plant physiology and morphogenesis, and their implications on drought stress tolerance, we used transgenic tobacco plants (AN1), which over-accumulated anthocyanins in all tissues. AN1 plants showed an altered phenotype in terms of leaf gas exchanges, leaf morphology, anatomy and metabolic profile, which conferred them with a higher drought tolerance compared to the wild-type plants. These results provide important insights for understanding the functional reason for anthocyanin accumulation in plants under stress

Biochemical, Physiological and Anatomical Mechanisms of Adaptation of Callistemon citrinus and Viburnum lucidum to NaCl and CaCl2 Salinization

Callistemon citrinus and Viburnum lucidum are very appreciated and widespread ornamental shrubs for their abundant flowering and/or brilliant foliage. The intrinsic tolerance to drought/salinity supports their use in urban areas and in xeriscaping. Despite adaptive responses of these ornamental species to sodium chloride (NaCl) have been extensively explored, little is known on the effects of other salt solution, yet iso-osmotic, on their growth, mineral composition and metabolism. The present research aimed to assess responses at the biochemical, physiological and anatomical levels to iso-osmotic salt solutions of NaCl and CaCl2 to discriminate the effects of osmotic stress and ion toxicity. The two ornamental species developed different salt-tolerance mechanisms depending on the salinity sources. The growth parameters and biomass production decreased under salinization in both ornamental species, independently of the type of salt, with a detrimental effect of CaCl2 on C. citrinus. The adaptive mechanisms adopted by the two ornamental species to counteract the NaCl salinity were similar, and the decline in growth was mostly related to stomatal limitations of net CO2 assimilation rate, together with the reduction in leaf chlorophyll content (SPAD index). The stronger reduction of C. citrinus growth compared to V. lucidum, was due to an exacerbated reduction in net photosynthetic rate, driven by both stomatal and non stomatal limitations. In similar conditions, V. lucidum exhibited other additional adaptive response, such as modification in leaf functional anatomical traits, mostly related to the reduction in the stomata size allowing plants a better control of stomata opening than in C. citrinus. However, C. citrinus plants displayed an increased ability to retain higher Cl- levels in leaves than in roots under CaCl2 salinity compared to V. lucidum, thus, indicating a further attempt to counteract chloride toxicity through an increased vacuolar compartmentalization and to take advantages of them as chip osmotica

Immunological evaluation of synthetic glycosylphosphatidylinositol glycoconjugates as vaccine candidates against malaria

Glycosylphosphatidylinositols (GPIs) are complex glycolipids present on the surfaces of Plasmodium parasites that may act as toxins during the progression of malaria. GPIs can activate the immune system during infection and induce the formation of anti-GPI antibodies that neutralize their activity. Therefore, an anti-toxic vaccine based on GPI glycoconjugates may prevent malaria pathogenesis. To evaluate the role of three key modifications on Plasmodium GPI glycan in the activity of these glycolipids, we synthesized and investigated six structurally distinct GPI fragments from P. falciparum. The synthetic glycans were conjugated to the CRM197 carrier protein and were tested for immunogenicity and efficacy as antimalarial vaccine candidates in an experimental cerebral malaria (ECM) model using C57BL/6JRj mice. Protection may be dependent on both, the antibody and cellular immune response to GPIs, and the elicited immune response depends on the orientation of the glycan, the number of mannoses in the structure and the presence of the phosphoethanolamine and inositol units. This study provides insights into the epitopes in GPIs and contributes to the development of GPI-based anti-toxin vaccine candidates against cerebral malaria

Morphological and physiological responses induced by protein hydrolysate-based biostimulant and nitrogen rates in greenhouse spinach

Plant-derived protein hydrolysates (PHs) are gaining prominence as biostimulants due to their potential to improve yield and nutritional quality even under suboptimal nutrient regimens. In this study, we investigated the effects of foliar application of a legume-derived PH (0 or 4 ml L−1) on greenhouse baby spinach (Spinacia oleracea L.) under four nitrogen (N) fertilization levels (0, 15, 30, or 45 kg ha−1) by evaluating morphological and colorimetric parameters, mineral composition, carbohydrates, proteins, and amino acids. The fresh yield in untreated and biostimulant-treated spinach plants increased in response to an increase in N fertilization from 1 up to 30 kg ha−1, reaching a plateau thereafter indicating the luxury consumption of N at 45 kg ha−1. Increasing N fertilization rate, independently of PH, lead to a significant increase of all amino acids with the exception of alanine, GABA, leucine, lysine, methionine, and ornithine but decreased the polyphenols content. Interestingly, the fresh yield at 0 and 15 kg ha−1 was clearly greater in PH-treated plants compared to untreated plants by 33.3% and 24.9%, respectively. This was associated with the presence in of amino acids and small peptides PH ‘Trainer®’, which act as signaling molecules eliciting auxin- and/or gibberellin-like activities on both leaves and roots and thus inducing a “nutrient acquisition response” that enhances nutrients acquisition and assimilation (high P, Ca, and Mg accumulation) as well as an increase in the photochemical efficiency and activity of photosystem II (higher SPAD index). Foliar applications of the commercial PH decreased the polyphenols content, but on the other hand strongly increased total amino acid content (+45%, +82%, and +59% at 0, 15, and 30 kg ha−1, respectively) but not at a 45-kg ha−1-rate. Overall, the use of PH could represent a sustainable tool for boosting yield and nitrogen use efficiency and coping with soil fertility problems under low input regimens

POSEIDON: An integrated system for analysis and forecast of hydrological, meteorological and surface marine fields in the Mediterranean area

The Mediterranean area is characterized by relevant hydrological, meteorological and marine processes developing at horizontal space-scales of the order of 1–100 km. In the recent past, several international programs have been addressed (ALPEX, POEM, MAP, etc.)to “resolving” the dynamics of such motions. Other projects (INTERREG-Flooding, MEDEX, etc.)are at present being developed with special emphasis on catastrophic events with major impact on human society that are, quite often, characterized in their manifestation by processes with the above-mentioned scales of motion. In the dynamical evolution of such events, however, equally important is the dynamics of interaction of the local (and sometimes very damaging)pro cesses with others developing at larger scales of motion. In fact, some of the most catastrophic events in the history of Mediterranean countries are associated with dynamical processes covering all the range of space-time scales from planetary to local. The Prevision Operational System for the mEditerranean basIn and the Defence of the lagOon of veNice (POSEIDON)is an integrated system for the analysis and forecast of hydrological, meteorological, oceanic fields specifically designed and set up in order to bridge the gap between global and local scales of motion, by modeling explicitly the above referred to dynamical processes in the range of scales from Mediterranean to local. The core of POSEIDON consists of a “cascade” of numerical models that, starting from global scale numerical analysisforecast, goes all the way to very local phenomena, like tidal propagation in Venice Lagoon. The large computational load imposed by such operational design requires necessarily parallel computing technology: the first model in the cascade is a parallelised version of BOlogna Limited Area Model (BOLAM)running on a Quadrics 128 processors computer (also known as QBOLAM). POSEIDON, developed in the context of a co-operation between the Italian Agency for New technologies, Energy and Environment (Ente per le Nuove tecnologie, l’Energia e l’Ambiente, ENEA)and the Italian Agency for Environmental Protection and Technical Services (Agenzia per la Protezione dell’Ambiente e per i Servizi Tecnici, APAT), has become operational in 2000 and we are presently in the condition of drawing some preliminary conclusions about its performance. In the paper we describe the scientific concepts that were at the basis of the original planning, the structure of the system, its operational cycle and some preliminary scientific and technical evaluations after two years of experimentation