Dynamics of mild strombolian activity on Mt. Etna

Here we report the first measurements of gas masses released during a rare period of strombolian activity at the Bocca Nuova crater, Mt. Etna, Sicily. UV camera data acquired for 195 events over an ≈27 minute period (27th July 2012) indicate erupted SO2 masses ranging from ≈0.1 to ≈14 kg per event, with corresponding total gas masses of ≈0.1 to 74 kg. Thus, the activity was characterised by more frequent and smaller events than typically associated with strombolian activity on volcanoes such as Stromboli. Events releasing larger measured gas masses were followed by relatively long repose periods before the following burst, a feature not previously reported on from gas measurement data. If we assume that gas transport within the magma can be represented by a train of rising gas pockets or slugs, then the high frequency of events indicates that these slugs must have been in close proximity. In this case the longer repose durations associated with the larger slugs would be consistent with interactions between adjacent slugs leading to coalescence, a process expedited close to the surface by rapid slug expansion. We apply basic modelling considerations to the measured gas masses in order to investigate potential slug characteristics governing the observed activity.We also cross correlated the acquired gas fluxes with contemporaneously obtained seismic data but found no relationship between the series in line with the mild form of manifest explosivity

Time-series analysis of fissure-fed multi-vent activity: a snapshot from the July 2014 eruption of Etna volcano (Italy)

The April to May 2010 eruption of Eyjafjallajökull (Iceland) volcano was characterized by a large compositional variability of erupted products. To contribute to the understanding of the plumbing system dynamics of this volcano, we present new EMPA and LA-ICP-MS data on groundmass glasses of ash particles and minerals erupted between April 15 and 22. The occurrence of disequilibrium textures in minerals, such as resorption and inverse zoning, indicate that open system processes were involved in determining the observed compositional variability. The variation of major and trace element data of glasses corroborates this hypothesis indicating that mixing between magma batches with different compositions interacted throughout the whole duration of the eruption. In particular, the arrival of new basaltic magma into the plumbing system of the volcano destabilized and remobilized magma batches of trachyandesite and rhyolite compositions that, according to geophysical data, might have intruded as sills over the past 20 years beneath the Eyjafjallajökull edifice. Two mixing processes are envisaged to explain the time variation of the compositions recorded by the erupted tephra. The first occurred between basaltic and trachyandesitic end-members. The second occurred between trachyandesite and rhyolites. Least-squares modeling of major elements supports this hypothesis. Furthermore, investi- gation of compositional histograms of trace elements allows us to estimate the initial proportions of melts that interacted to generate the compositional variability triggered by mixing of trachyandesites and rhyolites.Published515V. Dinamica dei processi eruttivi e post-eruttiviJCR Journa

The 2010 ash emissions at the summit craters of Mt Etna: Relationship with seismo-acoustic signals

Mt Etna volcano (Italy) typically generates lava fountains and Strombolian eruptions from the summit craters, producing significant emissions of tephra which may cause moderate to high impact both in the atmosphere and on the ground. However, we have also witnessed a number of minor ash emissions that, although far less powerful, may pose considerable volcanic hazards. In this paper, we deal with three ash emissions occurring in 2010 (8 April at Southeast Crater, 25 August at Bocca Nuova, and 14–15 November at Northeast Crater), correlating their volcanological features with the associated seismoacoustic signals. We provide details regarding the chronology, eruption column, dispersal of the deposit, and texture (grain size, componentry and morphology) of the emitted ash. Each eruptive episode has also been characterized by means of seismo-acoustic analyses evaluating the volcanic acoustic-seismic ratio (VASR). Furthermore, the source of volcanic tremor recorded from March to December 2010 was localized. The joint volcanological and seismo-acoustic analyses allowed distinguishing two main kinds of ash emissions: types a (8 April and 25 August) and b (14–15 November). Regarding the former, the accumulation of gas below a dense cap rock obstructing the conduit vent, giving rise, with the uncorking, to impulsive explosivity, was hypothesized. The latter type instead is characterized by a longer-lasting and less explosivity, likely due to the existence of open conduit conditions. Therefore, type b ash emissions are less hazardous than type a. This simple model, regarding minor explosive activity, may constitute a starting point to assess the volcanic risk from unexpected explosions.Published51-703V. Dinamiche e scenari eruttiviJCR Journalreserve

The 2010 ash emissions at the summit craters of Mt Etna: Relationship with seismo-acoustic signals

Mt Etna volcano (Italy) typically generates lava fountains and Strombolian eruptions from the summit craters, producing significant emissions of tephra which may cause moderate to high impact both in the atmosphere and on the ground. However, we have also witnessed a number of minor ash emissions that, although far less powerful, may pose considerable volcanic hazards. In this paper, we deal with three ash emissions occurring in 2010 (8 April at Southeast Crater, 25 August at Bocca Nuova, and 14–15 November at Northeast Crater), correlating their volcanological features with the associated seismoacoustic signals. We provide details regarding the chronology, eruption column, dispersal of the deposit, and texture (grain size, componentry and morphology) of the emitted ash. Each eruptive episode has also been characterized by means of seismo-acoustic analyses evaluating the volcanic acoustic-seismic ratio (VASR). Furthermore, the source of volcanic tremor recorded from March to December 2010 was localized. The joint volcanological and seismo-acoustic analyses allowed distinguishing two main kinds of ash emissions: types a (8 April and 25 August) and b (14–15 November). Regarding the former, the accumulation of gas below a dense cap rock obstructing the conduit vent, giving rise, with the uncorking, to impulsive explosivity, was hypothesized. The latter type instead is characterized by a longer-lasting and less explosivity, likely due to the existence of open conduit conditions. Therefore, type b ash emissions are less hazardous than type a. This simple model, regarding minor explosive activity, may constitute a starting point to assess the volcanic risk from unexpected explosions

A New Water-Soluble Calix[4]arene Ditopic Receptor Rigidified by Microsolvation: Acid-Base and Inclusion Properties

The coordination of a water molecule, bridging two distal phenolate anions of the tetrasulphonated calix[4]arene 1,3-dicarboxylic acid, has a remarkable influence on the acid base and inclusion properties of the ditopic receptor

A New Chiral Rigid Cone Water Soluble Peptidocalix[4]arene and its Inclusion Complexes with a-Amino Acids and Aromatic Ammonium Cations

A remarkable influence of the rigidity of the calix[4]arene platform in determining the recognition properties of mobile 2 and rigid cone 6 water soluble peptidocalix[4]arene receptors towards alpha-amino acids and aromatic quaternary ammonium cations has been foun

Charge Assisted Hydrophobic Binding of Ethanol Into the Cavity of Calix[4]Arene Receptors in Aqueous Solution

Ethanol is included into the hydrophobic cavity of the water soluble calixarenes 1 and 2 in aqueous solution, with the alkyl residue pointing towards the cavity and the hydroxyl group facing the bulk of the solvent. No inclusion is detected for 3, and this suggests that the sulphonate groups serve as anchoring points

Crystal structure of 6,6'-ditosyl-α-α'-trehalose-methanol-water (1/2/2), C52H68O30S4 ∙ 2CH3OH ∙ 2H2O

C54H80O32S4, monoclinic, P12il (No. 4), a = 17.334(6) A, b = 7.814(6) A, c = 24.278(6) A, β = 99.82(2)°, V= 3240.2 A, Z= 2, Rg(F) = 0.083, RJF) = 0.203, 7 = 293 K. Source of material The title compound was obtained by a one-step synthesis [1]. In order to select the primary site, the most reactive, the reaction was carried out at low temperature, followed by an accurate purification by reverse-phase chromatography, thus obtaining the product in short time and in good yield. The compound was crystallised from methanol and water mixture and is characterized by two independent molecules (A and B) in the asymmetric unit. Discussion Hydrogen atom s of the solvent molecules are not refined. The α,α'-trehalose is a peculiar disaccharide, in which two Dglucopyrasinic rings are linked by a bond between their anomeric carbon atoms, with a consequent non-reductive behaviour, while the molecule is symmetric. Owing to this peculiarity, this compound has attracted the interest of many reserchers and many derivatives have been synthesized. One of the key intermediates in these syntheses is the 6,6'-ditosyl-trehalose, which was first synthesized and characterized in 1958 [2]. The two independent molecules are almost superimposable with angle between the planes of the two glucosidic rings of 46.5(4)° and 53.5(5)° for molecule A and B, respectively. The major difference between the two independent molecules is represented by one dihedral angles in one tosyl moiety (C62A-062A-S2A-C7A = 69(1)° and C63B-063B-S1B-C4B = 177.1(8)°). Table 1. Data collection and handling. Crystal: colorless needle, size 0.2 χ 0.3 χ 0.6 mm Wavelength: Cu Ka radiation (1.54056 A) μ : 21.30 cm" ' Diffractometer, scan mode: Nonius CAD4-Turbo, ω/2

Synthesis of New Calixcrowns and their Anchoring to Silica Gel for the Selective Separation of Cs+ and K+

New 1,3-alternate calix[4]arenecrown-6 and calix[4]arene-crown-5, which are selective for caesium and potassium ions respectively, have been synthesized and linked covalently to silica gel via hydrosilanization and successfully employed for the chromatographic separation of Cs+ and K+ from alkali metal ions