scholarly journals Estimating the viscosity of volcanic melts from the vibrational properties of their parental glasses

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michele Cassetta ◽  
Danilo Di Genova ◽  
Marco Zanatta ◽  
Tiziana Boffa Ballaran ◽  
Alexander Kurnosov ◽  
...  
Keyword(s):  
Volcanic Eruptions ◽  
Peak Position ◽  
Accurate Estimation ◽  
Vibrational Properties ◽  
Ambient Conditions ◽  
Shear Moduli ◽  
Raman Spectroscopic ◽  
Viscosity Measurements ◽  
Fertile Ground ◽  
Melt Composition

AbstractThe numerical modelling of magma transport and volcanic eruptions requires accurate knowledge of the viscosity of magmatic liquids as a function of temperature and melt composition. However, there is growing evidence that volcanic melts can be prone to nanoscale modification and crystallization before and during viscosity measurements. This challenges the possibility of being able to quantify the crystal-free melt phase contribution to the measured viscosity. In an effort to establish an alternative route to derive the viscosity of volcanic melts based on the vibrational properties of their parental glasses, we have subjected volcanologically relevant anhydrous glasses to Brillouin and Raman spectroscopic analyses at ambient conditions. Here, we find that the ratio between bulk and shear moduli and the boson peak position embed the melt fragility. We show that these quantities allow an accurate estimation of volcanic melts at eruptive conditions, without the need for viscosity measurements. An extensive review of the literature data confirms that our result also holds for hydrous systems; this study thus provides fertile ground on which to develop new studies of the nanoscale dynamics of natural melts and its impact on the style of volcanic eruptions.

scholarly journals Experimental and Mathematical Tools to Predict Droplet Size and Velocity Distribution for a Two-Fluid Nozzle

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 231
Author(s):  
Sadegh Poozesh ◽  
Nelson K. Akafuah ◽  
Heather R. Campbell ◽  
Faezeh Bashiri ◽  
Kozo Saito
Keyword(s):  
Droplet Size ◽  
High Speed ◽  
Droplet Size Distribution ◽  
Integral Form ◽  
Accurate Estimation ◽  
Ambient Conditions ◽  
Computational Tools ◽  
Model Predictions ◽  
Model Fluids ◽  
Two Fluid

Despite progress in laser-based and computational tools, an accessible model that relies on fundamentals and offers a reasonably accurate estimation of droplet size and velocity is lacking, primarily due to entangled complex breakup mechanisms. Therefore, this study aims at using the integral form of the conservation equations to create a system of equations by solving which, the far-field secondary atomization can be analyzed through predicting droplet size and velocity distributions of the involved phases. To validate the model predictions, experiments are conducted at ambient conditions using water, methanol, and acetone as model fluids with varying formulation properties, such as density, viscosity, and surface tension. Droplet size distribution and velocity are measured with laser diffraction and a high-speed camera, respectively. Finally, an attempt is made to utilize non-scaled parameters to characterize the atomization process, useful for extrapolating the sensitivity analysis to other scales. The merit of this model lies in its simplicity for use in process control and optimization.

Raman spectroscopy of volcanic lavas and inclusions of relevance to astrobiological exploration

2010 ◽  
Vol 368 (1922) ◽  
pp. 3127-3135 ◽  
Author(s):  
Susana E. Jorge-Villar ◽  
Howell G. M. Edwards
Keyword(s):  
Volcanic Rocks ◽  
Volcanic Eruptions ◽  
Active Volcano ◽  
Spectroscopic Studies ◽  
Lava Flows ◽  
Pyroclastic Flows ◽  
Raman Spectroscopic ◽  
Normal Expectation ◽  
Terrestrial Environments ◽  
Volcanic Lava

Volcanic eruptions and lava flows comprise one of the most highly stressed terrestrial environments for the survival of biological organisms; the destruction of botanical and biological colonies by molten lava, pyroclastic flows, lahars, poisonous gas emissions and the deposition of highly toxic materials from fumaroles is the normal expectation from such events. However, the role of lichens and cyanobacteria in the earlier colonization of volcanic lava outcrops has now been recognized. In this paper, we build upon earlier Raman spectroscopic studies on extremophilic colonies in old lava flows to assess the potential of finding evidence of biological colonization in more recent lava deposits that would inform, first, the new colonization of these rocks and also provide evidence for the relict presence of biological colonies that existed before the volcanism occurred and were engulfed by the lava. In this research, samples were collected from a recent expedition to the active volcano at Kilauea, Hawaii, which comprises very recent lava flows, active fumaroles and volcanic rocks that had broken through to the ocean and had engulfed a coral reef. The Raman spectra indicated that biological and geobiological signatures could be identified in the presence of geological matrices, which is encouraging for the planned exploration of Mars, where it is believed that there is evidence of an active volcanism that perhaps could have preserved traces of biological activity that once existed on the planet’s surface, especially in sites near the old Martian oceans.

Measurement of the shear properties of clear wood by the Arcan test

Holzforschung ◽  
2009 ◽  
Vol 63 (2) ◽  
Author(s):  
José Xavier ◽  
Marcelo Oliveira ◽  
José Morais ◽  
Tiago Pinto
Keyword(s):  
Shear Strain ◽  
Ad Hoc ◽  
Test Method ◽  
Accurate Estimation ◽  
Correction Factors ◽  
Clear Wood ◽  
Shear Properties ◽  
Shear Moduli ◽  
Gauge Section ◽  
Thickness Shear

Abstract In this work, the identification of the shear properties of maritime pine (Pinus pinaster Ait.) wood was investigated by applying the Arcan test method. For this purpose, an ad hoc Arcan fixture was designed for which clear wood samples could be tested along all the material planes of symmetry – LR, LT and RT planes. For the accurate evaluation of the shear moduli, correction factors taking into account the non-uniformity of the shear stress and the shear strain distributions at the gauge section were determined with finite element analyses. Experimentally, two 0/90 rosettes were glued on both frontal and back surfaces of the specimens in order to take into account any through-to-thickness shear strain variation. It was found that the Arcan test is suitable for the identification of the shear moduli of wood in all its natural planes. The failure of the Arcan specimens systematically occurred under a concentrated stress state nearby the V-notches. Nevertheless, it was shown that an accurate estimation of the shear strengths of wood can be achieved by the Arcan test.

Mechanochemically Synthesised ZnxCd1-xS Nanoparticles for Solar Energy Applications

2012 ◽  
Vol 18-19 ◽  
pp. 247-256 ◽  
Author(s):  
Erika Dutková ◽  
Peter Baláz ◽  
Parviz Pourghahramani ◽  
Vladimír Balek ◽  
Anh V. Nguyen ◽  
...  
Keyword(s):  
Cadmium Acetate ◽  
High Energy ◽  
Peak Position ◽  
Mechanochemical Treatment ◽  
Morphological Properties ◽  
Molar Ratio ◽  
Cubic Phase ◽  
Ambient Conditions ◽  
Structural Refinement ◽  
Additional Information

The mechanochemical solid-state synthesis of ZnxCd1-xS nanoparticles from zinc acetate, cadmium acetate and sodium sulphide in a planetary laboratory mill is described. Through changing the molar ratio of the Zn and Cd precursors, ZnxCd1-xS nanoparticles of different composition were prepared. Structural, surface and morphological properties were investigated by XRD, XPS, SEM and UV-VIS. Diffusion structural diagnostics was characterised by the emanation thermal analysis (ETA) results measured on heating of the samples. The cubic phase was found to be stable under mechanochemical treatment, as determined by XRD. The mixed phases were found to have ideal solution behaviours. In addition, microstructural characterisation indicated that mechanochemical treatment resulted in a structural refinement with a surface weighted crystallite size about 2 nm. The additional information of microstructure development and transport properties of the samples on heating was obtained by ETA. The calculated lattice parameters of mixed crystals linearly depend on the composition of ZnxCd1-xS nanoparticles. The S(2p), Zn(2p) and Cd(3d) core levels of the ZnxCd1-xS nanocrystallites reveal two different types of sulphur, zinc and cadmium unlike bulk CdS and ZnS. The calculated results indicate that the quantum-size effect in the nanoparticles is not negligible. The differences in the absorption edge and the emission peak position of the nanoparticles depend not only composition. Applied high-energy milling is a facile, efficient, and scalable process that does not require a solvent and can be performed under ambient conditions. Therefore, it is a promising candidate for the production of nanocrystalline materials.

scholarly journals Decadal Modeling (2004-2021) Ecosystem Recovery Impacted by Mount Semeru Eruption Volcanic Activities using Vegetation Succession as a Proxy in the Lava Flow Stream

2021 ◽  
Author(s):  
Andri Wibowo
Keyword(s):  
Lava Flow ◽  
Volcanic Eruptions ◽  
Natural Process ◽  
Vegetation Succession ◽  
Tree Line ◽  
Ecosystem Recovery ◽  
Barren Land ◽  
Succession Rate ◽  
Fertile Ground ◽  
Ecosystem Transformation

Volcano eruptions undoubtly cause environmental impacts and damages. After the eruption, there will be vast barren land that was previously fertile ground covered by vegetation and tree line. Lava from an eruption will flow to the land via a river stream, destroying everything in its path, including vegetation. While the ecosystem actually has an ability to recover. The natural process of ecosystem recovery is related to the succession of vegetation. Then this study aims to assess and model how the ecosystem can recover and how the vegetation can respond to the damage caused by Semeru, one of the most powerful volcanic eruptions on Java island. The study areas were 2 regions that had been impacted by the Semeru lava flow for the period of 2004–2021. Based on the results, the ecosystem recovery of Semeru post-eruption was achieved within 5 years. During this time, the vegetation succession rate, as measured by vegetation cover, increased nearly ten folds. The post-eruption ecosystem recovery was indicated by the ecosystem transformation from a damaged ecosystem indicated by a lava-dominated surface to one with the presence of vegetation and hardened lava. The recovered ecosystem in Semeru's posteruption was composed of solid lava covers (39%), liquid lava (34%), and vegetation covers (27%).Then, the presence of vegetation and its succession rate can be used as a proxy of ecosystem recovery after a vast volcanic eruption.

scholarly journals Single-crystal elasticity of iron-bearing phase E and seismic detection of water in Earth's upper mantle

2019 ◽  
Vol 104 (10) ◽  
pp. 1526-1529 ◽  
Author(s):  
Niccolò Satta ◽  
Hauke Marquardt ◽  
Alexander Kurnosov ◽  
Johannes Buchen ◽  
Takaaki Kawazoe ◽  
...  
Keyword(s):  
Sound Wave ◽  
Upper Mantle ◽  
Stiffness Tensor ◽  
Ambient Conditions ◽  
Brillouin Spectroscopy ◽  
Shear Moduli ◽  
Mantle Minerals ◽  
Wave Velocities ◽  
Seismic Detection ◽  
Iron Bearing

Abstract The elastic properties of Mg2.12(2)Fe0.21(2)Ni0.01Si1.15(1)O6H2.67(8) phase E single crystals with Fe3+/ΣFe = 0.25(3) have been determined by Brillouin spectroscopy at ambient conditions. We find that that the elasticity of iron-bearing phase E is described by the six independent stiffness tensor components (all in units of GPa): C11 = 192.2(6), C12 = 56.4(8), C13 = 43.5(8), C14 = –4.3(3), C33 = 192.1(7), C44 = 46.4(3). The Voigt-Reuss-Hill averages of bulk and shear moduli are 95.9(4) and 59.6(2) GPa, respectively. The aggregate velocities of iron-bearing phase E are νP = 7.60(2) and νS = 4.43(1) km/s, markedly lower than those of major mantle minerals at ambient conditions. Modeling based on our results suggests that the presence of iron-bearing phase E may reduce the sound wave velocities in upper mantle and transition zone rocks, making it a possible target for future seismological investigations aiming to map hydration in subducting slabs.

scholarly journals Magnetic oxygen stored in quasi-1D form within BaAl2O4 lattice

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Martina Vrankić ◽  
Ankica Šarić ◽  
Sanja Bosnar ◽  
Damir Pajić ◽  
Jure Dragović ◽  
...  
Keyword(s):  
Magnetic Measurements ◽  
Condensed Matter ◽  
Magnetic Ordering ◽  
Inorganic Materials ◽  
Dimensional Chain ◽  
Ambient Conditions ◽  
Gas Atmosphere ◽  
Fertile Ground ◽  
Reduce Energy Consumption ◽  
Low Dimensional

Abstract Inorganic materials that enable a link between the storage and release of molecular oxygen offer a fertile ground in continuous quest for the applications that can potentially reduce energy consumption and thus minimize adverse effects on the environment. Herein, we address reversible intake/release of an oxygen within the BaAl2O4 material as evidenced by unexpected magnetic ordering. Magnetic measurements unveil that an oxygen is stored in the form of condensed matter, creating a kind of low dimensional, chain-like assembly within the tunnels of BaAl2O4 structure. We demonstrate that oxygen is adsorbed simply by staying in air, at ambient conditions, and released relatively quickly by staying in the He or other gas atmosphere of several millibars pressure even at 300 K.

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