The response of a small stream in the Lesni potok forested catchment, central Czech Republic, to a short-term in-stream acidification

International audienceLesni Potok stream drains a forested headwater catchment in the central Czech Republic. It was artificially acidified with hydrochloric acid (HC1) for four hours to assess the role of stream substrate in acid-neutralisation and recovery. The pH was lowered from 4.7 to 3.2. Desorption of Ca and Mg and desorption or solution of Al dominated acid-neutralisation; Al mobilisation was more important later. The stream substrate released 4,542 meq Ca, 1,184 meq Mg, and 2,329 meq Al over a 45 m long and 1 m wide stream segment; smaller amounts of Be, Cd, Fe, and Mn were released. Adsorption of SO42- and desorption of F? occurred during the acidification phase of the experiment. The exchange reactions were rapidly reversible for Ca, Mg and SO42-; but not symmetric as the substrate resorbed 1083, 790 and 0 meq Ca, Mg, and Al, respectively, in a 4-hour recovery period. Desorption of SO42-; occurred during the resorption of Ca and Mg. These exchange and dissolution reactions delay acidification, diminish the pH depression and retard recovery from episodic acidification. The behaviour of the stream substrate-water interaction resembles that for soil?soil water interactions. A mathematical dynamic mass-balance based model, MASS (Modelling Acidification of Stream pediments), was developed which simulates the adsorption and desorption of base cations during the experiment and was successfully calibrated to the experimental data. Keywords: Al, Ca, Mg, base cations, acid-neutralisation, stream acidification, recovery, stream sediment, experiment, modelling, adsorption, desorption, adsorption, Czech Republic, Lesni Poto

Le Elezioni Politiche 2013

Le elezioni politiche del 24 e 25 febbraio 2013 hanno sancito un forte cambiamento della struttura del sistema partitico italiano. In un contesto di altissima volatilità elettorale e di accelerato declino della partecipazione al voto, il sistema è divenuto sostanzialmente tripolare, dopo vent’anni di strutturazione e tenuta del bipolarismo. A questo esito hanno concorso da un lato l’erosione dei principali schieramenti politici che a partire dal novembre 2011 avevano sostenuto l’esperienza del governo Monti (nonché la deludente prova elettorale dello stesso Presidente del Consiglio uscente), e dall’altro lo straordinario successo del Movimento 5 stelle. Quest’ultimo, al primo test elettorale di livello nazionale, ha raccolto un risultato sorprendente, giungendo ad oltre un quarto dei voti validi. Siamo di fronte ad una parentesi momentanea dovuta all’effetto combinato di crisi economica e crisi politica, oppure le contraddizioni interne alla Seconda Repubblica l’hanno condotta effettivamente al suo crepuscolo? Come uscirà il sistema partitico italiano da questa nuova fase di destabilizzazione? Questo quarto Dossier CISE, che raccoglie contributi apparsi sul sito web del Cise prima e dopo le elezioni, fornisce una prima analisi del voto, presentando elaborazioni su dati aggregati, stime dei flussi elettorali, alcune prime analisi su dati di sondaggio, nonché una panoramica dei nuovi eletti e un’appendice ricca di tabelle e mappe riassuntive del risultato elettorale. Come i precedenti Dossier, si tratta di uno strumento prodotto rapidamente all’indomani del voto, con l’intento di suggerire primi spunti di interpretazione da approfondire in seguito, cercando di contribuire alla lettura di un risultato elettorale cruciale, in una delicata fase di cambiamento del sistema partitico italiano

Fullerene-driven encapsulation of a luminescent Eu(III) complex in carbon nanotubes

A novel CNT-based hybrid luminescent material was obtained via encapsulation of a C60-based Eu(III) complex into single-, double- and multi-walled carbon nanotubes (SWCNTs, DWCNTs and MWCNTs, respectively). Specifically, a luminescent negatively charged Eu(III) complex, electrostatically bonded to an imidazolium-functionalized fullerene cage, was transported inside CNTs by exploiting the affinity of fullerenes for the inner surface of these carbonaceous containers. The filling was performed under supercritical CO2 (scCO2) conditions to facilitate the entrapment of the ion-paired assembly. Accurate elemental, spectroscopic and morphological characterization not only demonstrated the efficiency of the filling strategy, but also the occurrence of nano-ordering of the encapsulated supramolecular luminophores when SWCNTs were employed

Copper and Zinc Accumulation in Young Leaves of Eruca sativa (L.) Grown in Soilless Culture

Heavy metals are environmental pollutants that cause toxicity in plants and represent a risk for human health, linked to bioaccumulation through the food chain. However, excess accumulation may not occur in young plants in the early stages of exposure to the toxic element. In the present work, rocket (Eruca sativa L.) plants grown in hydroponics were exposed for three weeks to excess concentrations (25, 50, or 100 μM) of Cu or Zn in the nutrient solution and were more sensitive to Cu than Zn toxicity. However, a significant decrease in the leaf biomass production as compared with the control was observed only after two or three weeks, and only minor signals of metal-induced adverse effects were evidenced concerning photosynthesis, oxidative stress indicators, antioxidant metabolites, and macronutrients. After two or three weeks, the leaf level of Cu occasionally approached the upper value associated with the recommended limits of dietary intake for human adults. However, as rocket leaves are commercialized when they achieve a 10–15 cm length, after one week of cultivation in perlite, the plants had an adequate size without metal contamination and could be considered suitable for the food market, even after exposure to Cu or Zn concentrations up to 100 μM

Iodine biofortification of sweet basil and lettuce grown in two hydroponic systems

Two hydroponic techniques (floating system and aeroponics) were assessed for iodine (I) biofortification of sweet basil (Ocimum basilicum L.) and baby-leaf lettuce (Lactuca sativa L.). Iodine was supplemented by adding KI into the nutrient solution to achieve a final I concentration of 10 μM. Shoot biomass production and leaf concentration of I, nitrates, total phenols and pigments were measured on the occasion of two successive cuts, 14 and 28 days after transplanting. In both the hydroponic systems, the supplementation of KI represented an effective method for the biofortification of basil as it did not affect the plant growth, while it moderately reduced the biomass production in lettuce. Leaf I accumulation occurred to a greater extent in aeroponics than the floating system in both species. In KI-treated basil plants, leaf I content ranged between 9.76 and 23.58 mg kg− 1 FW. Consequently, 6 g of fresh basil leaves, which is contained in a portion of Italian pesto sauce (12 g), could satisfy 40%–94% of the Recommended Daily Intake (RDI) of iodine for healthy adults (150 μg day− 1). In lettuce, leaf I contents of first-cut leaves were 1.55 and 3.60 mg kg− 1 FW, in the floating system and aeroponics, respectively. Therefore, a serving size of 26 g of lettuce containing I from 1.55 (floating culture) to 3.60 (aeroponics) mg kg− 1 FW could satisfy 27 % to 62 % of the RDI of iodine. Lettuce grew much less in the floating system than aeroponics, probably because of the lower dissolved oxygen level in the nutrient solution as compared to aeroponics. Basil was less sensitive to the oxygen availability in the root zone, since no differences were detected between the two hydroponic systems in terms of fresh and dry biomass

Non-dimensional numerical analysis of coupled Metal Hydride-Phase Change Material hydrogen storage system

Efficient storage solutions that decouple energy use and production are pivotal for the green energy transition, due to the non-controllable operation of solar and wind power. In this scenario, hydrogen, and in particular metal hydride storage, has shown excellent potential. In this paper we develop a mathematical model to characterize the operation of several cylindrical Metal Hydride-Phase Change Material tank layouts and to determine the improved configuration in terms of charge/discharge time and power. We use non-dimensional parameters to guide the design of a hybrid metal hydride-phase change material hydrogen storage system. We introduce a critical value for the state of charge of the storage system, equal to φc∗=0.15, above which heat exchange dominates the process efficiency. Results show that, when varying the canister main aspect ratio between 5 and 100, the equivalent inlet/outlet power increases by a factor ≈10. The ratio of the thermal conductivities is found to have a significant impact in the desorption phase, where the equivalent power increases by a factor ≈4 when raising the ratio from 0.1 to 0.8. Finally, we evaluate three case studies by introducing three different improved configurations and comparing them with the baseline design. A LaNi5/LiNO3−3H2O system for the storage of 1kWh of H2 exhibits 5.65kW and 0.83kW of average power in absorption and desorption, respectively. Such an improved configuration is 93% faster in charge/discharge process with respect to the baseline design. A coupled Mg2NiH4 - NaNO3 exhibits 2.93 kW and 0.30 kW of average power in absorption and desorption, respectively. This configuration is 81% faster than the baseline design. A coupled Mg2NiH4 - KNO3 exhibits 1.66 kW and 0.56 kW of average power in absorption and desorption, while the cycle time is reduced from 1220 min to 147 min (−88%)

Crisi e Rimobilitazione : Gli italiani, la politica, i partiti nelle indagini campionarie del CISE (2011-2012)

Nella primavera 2012, pochi mesi dopo l’insediamento del governo Monti, i partiti italiani toccavano il punto più basso della loro presa sull’opinione pubblica italiana: altissime percentuali di astenuti e indecisi, con un elettorato demotivato da un’o!erta politica ancora incerta (anche a causa della di"cile convivenza con un governo tecnico) e quindi incapace di strategie innovative. Tuttavia, è forse vero che la politica ha orrore del vuoto: l’imminenza delle elezioni amministrative (del maggio 2012) e soprattutto l’ingresso nell’ultimo anno prima delle elezioni politiche segnano una ripresa dell’iniziativa politica, sia da parte dei partiti esistenti che da parte di nuovi attori politici. Il primo a muoversi è il Movimento 5 Stelle, con un’aggressiva strategia per le elezioni amministrative, in cui registrerà un grande successo. Ma in secondo luogo è il centrosinistra a gettarsi in una impegnativa e rischiosa strategia politica basata sulle primarie, che otterrà tuttavia il grande risultato di una signifativa rimobilitazione del proprio elettorato. Tutte queste tendenze sono state puntualmente registrate dalla serie di indagini demoscopiche Osservatorio Politico CISE, condotte ogni sei mesi a partire dalla primavera 2011. I risultati di queste indagini, già pubblicati sul sito web Cise nel corso del 2012, sono raccolti oggi in questo secondo Dossier CISE. Una riflessione sul clima di opinione pubblica che conduce alle elezioni politiche del 2013, che vuole fornire dati utili per interpretare le ultime fasi della campagna elettorale e per inquadrare l’ormai imminente risultato delle elezioni

Direction-dependent secondary bonds and their stepwise melting in a uracil-based molecular crystal studied by infrared spectroscopy and theoretical modeling

Three types of supramolecular interactions are identified in the three crystallographic directions in crystals of 1,4-bis[(1-hexylurac-6-yl)ethynyl]benzene, a uracil-based molecule with a linear backbone. These three interactions, characterized by their strongest component, are: intermolecular double H-bonds along the molecular axis, London dispersion interaction of hexyl chains connecting these linear assemblies, and $\pi$--$\pi$ stacking of the aromatic rings perpendicular to the molecular planes. On heating, two transitions happen, disordering of hexyl chains at 473 K, followed by H-bond melting at 534 K. The nature of the bonds and transitions was established by matrix-isolation and temperature-dependent infrared spectroscopy and supported by theoretical computations