Oceans Melting Greenland OMG 2017 Media Reel

NASA Image and Video Library

2017-12-05

The Oceans Melting Greenland mission seeks to understand how ocean water is contributing to ice loss in Greenland. In October 2017, mission scientists and crew dropped 240 ocean probes from a C-130 aircraft into the waters around Greenland to measure ocean temperature and salinity. Footage includes aerial shots of Greenland landscapes, interior and exterior shots of the aircraft with crew and scientists at work, and shots from a chase plane showing the probes dropping.

Recycling of rare earth metals from rare earth-transition metal alloy scrap by liquid metal extraction

DOEpatents

Ellis, T.W.; Schmidt, F.A.

1995-08-01

A method is described for treating rare earth metal-bearing scrap, waste or other material (e.g. Nd--Fe--B or Dy--Tb--Fe scrap) to recover the rare earth metal comprising melting the rare earth metal-bearing material, melting a Group IIA metal extractant, such as Mg, Ca, or Ba, in which the rare earth is soluble in the molten state, and contacting the melted material and melted extractant at a temperature and for a time effective to extract the rare earth from the melted material into the melted extractant. The rare earth metal is separated from the extractant metal by vacuum sublimation or distillation. 2 figs.

Physical phenomena in containerless glass processing

NASA Technical Reports Server (NTRS)

Subramanian, R. S.; Cole, R.; Annamalai, P.; Jayaraj, K.; Kondos, P.; Mcneil, T. J.; Shankar, N.

1982-01-01

Experiments were conducted on bubble migration in rotating liquid bodies contained in a sphere. Experiments were initiated on the migration of a drop in a slightly less dense continuous phase contained in a rotating sphere. A refined apparatus for the study of thermocapillar flow in a glass melt was built, and data were acquired on surface velocities in the melt. Similar data also were obtained from an ambient temperature fluid model. The data were analyzed and correlated with the aid of theory. Data were obtained on flow velocities in a pendant drop heated from above. The motion in this system was driven principally by thermocapillarity. An apparatus was designed for the study of volatilization from a glass melt.

Solidification of Undercooled Melts of Al-Based Alloys on Earth and in Space

NASA Astrophysics Data System (ADS)

Herlach, Dieter M.; Burggraf, Stefan; Galenko, Peter; Gandin, Charles-André; Garcia-Escorial, Asuncion; Henein, Hani; Karrasch, Christian; Mullis, Andrew; Rettenmayr, Markus; Valloton, Jonas

2017-08-01

Containerless processing of droplets and drops by atomization and electromagnetic levitation are applied to undercool metallic melts and alloys prior to solidification. Heterogeneous nucleation on crucible walls is completely avoided giving access to large undercoolings. Experiments are performed both under terrestrial (1 g) conditions and in reduced gravity ( µg) as well. Microgravity conditions are realized by the free fall of small droplets during atomization of a spray of droplets, individual drops in a drop tube and by electromagnetic levitation of drops during parabolic flights, sounding rocket missions, and using the electro-magnetic levitator multi-user facility on board the International Space Station. The comparison of both sets of experiments in 1 g and µg leads to an estimation of the influence of forced convection on dendrite growth kinetics and microstructure evolution.

Drop-on-Demand System for Manufacturing of Melt-based Solid Oral Dosage: Effect of Critical Process Parameters on Product Quality.

PubMed

Içten, Elçin; Giridhar, Arun; Nagy, Zoltan K; Reklaitis, Gintaras V

2016-04-01

The features of a drop-on-demand-based system developed for the manufacture of melt-based pharmaceuticals have been previously reported. In this paper, a supervisory control system, which is designed to ensure reproducible production of high quality of melt-based solid oral dosages, is presented. This control system enables the production of individual dosage forms with the desired critical quality attributes: amount of active ingredient and drug morphology by monitoring and controlling critical process parameters, such as drop size and product and process temperatures. The effects of these process parameters on the final product quality are investigated, and the properties of the produced dosage forms characterized using various techniques, such as Raman spectroscopy, optical microscopy, and dissolution testing. A crystallization temperature control strategy, including controlled temperature cycles, is presented to tailor the crystallization behavior of drug deposits and to achieve consistent drug morphology. This control strategy can be used to achieve the desired bioavailability of the drug by mitigating variations in the dissolution profiles. The supervisor control strategy enables the application of the drop-on-demand system to the production of individualized dosage required for personalized drug regimens.

The undercooling of liquids

NASA Technical Reports Server (NTRS)

Turnbull, D.

1984-01-01

The formation by melt quenching of such metastable structures as glassy or microcrystalline solids and highly supersaturated solutions is made possible by the extreme resistance of most melts to homophase crystal nucleation at deep undercooling. This nucleation resistance contrasts sharply with the very low kinetic resistance to the movement of crystal-melt interfaces, once formed, in metals and other fluid systems at even minute undercooling. The methods of nucleation study which have proven especially effective in bypassing nucleation by heterophase impurities thereby exposing the high resistance of melts to homophase nucleation may be summarized as follows: observation of the crystallization behavior of dispersed small droplets; drop tube experiments in which liquid drops solidify, under containerless conditions, during their fall in the tube; and observation of the crystallization of bulk specimens immersed in fluxes chosen to dissolve or otherwise deactivate (e.g., by wetting) heterophase nucleants. This method has proven to be remarkably effective in deactivating such nucleants in certain pure metals.

Experimental studies in fluid mechanics and materials science using acoustic levitation

NASA Technical Reports Server (NTRS)

Trinh, E. H.; Robey, J.; Arce, A.; Gaspar, M.

1987-01-01

Ground-based and short-duration low gravity experiments have been carried out with the use of ultrasonic levitators to study the dynamics of freely suspended liquid drops under the influence of predominantly capillary and acoustic radiation forces. Some of the effects of the levitating field on the shape as well as the fluid flow fields within the drop have been determined. The development and refinement of measurement techniques using levitated drops with size on the order of 2 mm in diameter have yielded methods having direct application to experiments in microgravity. In addition, containerless melting, undercooling, and freezing of organic materials as well as low melting metals have provided experimental data and observations on the application of acoustic positioning techniques to materials studies.

The influence of partial melting and melt migration on the rheology of the continental crust

NASA Astrophysics Data System (ADS)

Cavalcante, Geane Carolina G.; Viegas, Gustavo; Archanjo, Carlos José; da Silva, Marcos Egydio

2016-11-01

The presence of melt during deformation produces a drastic change in the rheological behavior of the continental crust; rock strength is decreased even for melt fractions as low as ∼7%. At pressure/temperature conditions typical of the middle to lower crust, melt-bearing systems may play a critical role in the process of strain localization and in the overall strength of the continental lithosphere. In this contribution we focus on the role and dynamics of melt flow in two different mid-crustal settings formed during the Brasiliano orogeny: (i) a large-scale anatectic layer in an orthogonal collision belt, represented by the Carlos Chagas anatexite in southeastern Brazil, and (ii) a strike-slip setting, in which the Espinho Branco anatexite in the Patos shear zone (northeast Brazil) serves as an analogue. Both settings, located in eastern Brazil, are part of the Neoproterozoic tectonics that resulted in widespread partial melting, shear zone development and the exhumation of middle to lower crustal layers. These layers consist of compositionally heterogeneous anatexites, with variable former melt fractions and leucosome structures. The leucosomes usually form thick interconnected networks of magma that reflect a high melt content (>30%) during deformation. From a comparison of previous work based on detailed petrostructural and AMS studies of the anatexites exposed in these areas, we discuss the rheological implications caused by the accumulation of a large volume of melt ;trapped; in mid-crustal levels, and by the efficient melt extraction along steep shear zones. Our analyses suggest that rocks undergoing partial melting along shear settings exhibit layers with contrasting competence, implying successive periods of weakening and strengthening. In contrast, regions where a large amount of magma accumulates lack clear evidence of competence contrast between layers, indicating that they experienced only one major stage of dramatic strength drop. This comparative analysis also suggests that the middle part of both belts contained large volumes of migmatites, attesting that the orogenic root was partially molten and encompassed more than 30% of granitic melt at the time of deformation.

Coupled petrological-geodynamical modeling of a compositionally heterogeneous mantle plume

NASA Astrophysics Data System (ADS)

Rummel, Lisa; Kaus, Boris J. P.; White, Richard W.; Mertz, Dieter F.; Yang, Jianfeng; Baumann, Tobias S.

2018-01-01

Self-consistent geodynamic modeling that includes melting is challenging as the chemistry of the source rocks continuously changes as a result of melt extraction. Here, we describe a new method to study the interaction between physical and chemical processes in an uprising heterogeneous mantle plume by combining a geodynamic code with a thermodynamic modeling approach for magma generation and evolution. We pre-computed hundreds of phase diagrams, each of them for a different chemical system. After melt is extracted, the phase diagram with the closest bulk rock chemistry to the depleted source rock is updated locally. The petrological evolution of rocks is tracked via evolving chemical compositions of source rocks and extracted melts using twelve oxide compositional parameters. As a result, a wide variety of newly generated magmatic rocks can in principle be produced from mantle rocks with different degrees of depletion. The results show that a variable geothermal gradient, the amount of extracted melt and plume excess temperature affect the magma production and chemistry by influencing decompression melting and the depletion of rocks. Decompression melting is facilitated by a shallower lithosphere-asthenosphere boundary and an increase in the amount of extracted magma is induced by a lower critical melt fraction for melt extraction and/or higher plume temperatures. Increasing critical melt fractions activates the extraction of melts triggered by decompression at a later stage and slows down the depletion process from the metasomatized mantle. Melt compositional trends are used to determine melting related processes by focusing on K2O/Na2O ratio as indicator for the rock type that has been molten. Thus, a step-like-profile in K2O/Na2O might be explained by a transition between melting metasomatized and pyrolitic mantle components reproducible through numerical modeling of a heterogeneous asthenospheric mantle source. A potential application of the developed method is shown for the West Eifel volcanic field.

Steam distillation/drop-by-drop extraction with gas chromatography-mass spectrometry for fast determination of volatile components in jujube (Ziziphus jujuba Mill.) extract.

PubMed

Sun, Shi-Hao; Chai, Guo-Bi; Li, Peng; Xie, Jian-Ping; Su, Yue

2017-10-13

Jujube extract is commonly used as a food additive and flavoring. The unique jujube aroma and the mild sweet aroma of the extract are critical factors that determine product quality and affect consumer acceptability. The aroma changes with changes in the extraction condition, which is typically dependent on the characteristics of volatile oils in the extract. Despite their importance, the volatile oils of jujube extract have received less attention compared with the soluble components. So, an appropriate qualitative and quantitative method for determination of the volatile oils is vitally important for quality control of the product. A method coupling steam distillation/drop-by-drop extraction with gas chromatography-mass spectrometry (S3DE/GC-MS) was developed to determine the volatile components of jujube extract. Steam distillation was coupled with solvent extraction; the resulting condensate containing volatile components from jujube extract was drop-by-drop extracted using 2 mL of methyl tertiary butyl ether. The solvent served two purposes. First, the solvent extracted the volatile components from the condensate. Second, the volatile components were pre-concentrated by drop-by-drop accumulation in the solvent. As a result, the extraction, separation, and concentration of analytes in the sample were simultaneously completed in one step. The main parameters affecting the S3DE procedure, such as the water steam bubbling rate, extraction solvent volume, sample weight and S3DE time, were optimized. The standard addition approach was essential to obtain accurate measurements by minimizing matrix effects. Good linearity (R 2  ≥ 0.9887) and good repeatability (RSDs ≤ 10.35%, n = 5) for 16 analytes in spiked standard analyte samples were achieved. With the S3DE/GC-MS method, seventy-six volatile compounds from jujube extract were identified and the content of 16 compounds was measured. The results were similar to those from simultaneous distillation extraction. The developed method was simple, fast, effective, sensitive, and provided an overall profile of the volatile components in jujube extract. Thus, this method can be used to determine the volatile components of extracts. Graphical abstract The diagram of steam distillation/drop-by-drop extraction device.

Reduction, partial evaporation, and spattering - Possible chemical and physical processes in fluid drop chondrule formation

NASA Technical Reports Server (NTRS)

King, E. A.

1983-01-01

The major chemical differences between fluid drop chondrules and their probable parent materials may have resulted from the loss of volatiles such as S, H2O, Fe, and volatile siderophile elements by partial evaporation during the chondrule-forming process. Vertical access solar furnace experiments in vacuum and hydrogen have demonstrated such chemical fractionation trends using standard rock samples. The formation of immiscible iron droplets and spherules by in situ reduction of iron from silicate melt and the subsequent evaporation of the iron have been observed directly. During the time that the main sample bead is molten, many small spatter spherules are thrown off the main bead, thereby producing many additional chondrule-like melt spherules that cool rapidly and generate a population of spherules with size frequency distribution characteristics that closely approximate some populations of fluid drop chondrules in chondrites. It is possible that spatter-produced fluid drop chondrules dominate the meteoritic fluid drop chondrule populations. Such meteoritic chondrule populations should be chemically related by various relative amounts of iron and other volatile loss by vapor fractionation.

New Method of Filling of High-Temperature Fixed-Point Cells Based on Metal-Carbon Eutectics/Peritectics

NASA Astrophysics Data System (ADS)

Khlevnoy, B. B.; Grigoryeva, I. A.; Ibragimov, N. A.

2011-08-01

A new method of filling of high-temperature fixed-point cells based on metal-carbon eutectics and peritectics is suggested and tested. In this method a metal and carbon powder mixture is introduced not directly into the crucible, but into an additional container located just above the crucible. The mixture melts inside the container, and the already molten eutectic drops through a small hole in the bottom of the container and fills the crucible drop by drop. The method can be used to obtain a uniform ingot without porous or foundry cavities, to minimize the risk of contamination, and to avoid some other disadvantages. The method was applied to fabricate Re-C and WC-C cells using 5N purity materials. The cells demonstrated a good plateau shape with melting ranges of 0.2 K and 80 mK for Re-C and WC-C, respectively. The Re-C cell was compared with a cell built at NMIJ and showed good agreement with a difference of melting temperatures of only 45 mK.

An Iron-Rain Model for Core Formation on Asteroid 4 Vesta

NASA Technical Reports Server (NTRS)

Kiefer, Walter S.; Mittlefehldt, David W.

2016-01-01

Asteroid 4 Vesta is differentiated into a crust, mantle, and core, as demonstrated by studies of the eucrite and diogenite meteorites and by data from NASA's Dawn spacecraft. Most models for the differentiation and thermal evolution of Vesta assume that the metal phase completely melts within 20 degrees of the eutectic temperature, well before the onset of silicate melting. In such a model, core formation initially happens by Darcy flow, but this is an inefficient process for liquid metal and solid silicate. However, the likely chemical composition of Vesta, similar to H chondrites with perhaps some CM or CV chondrite, has 13-16 weight percent S. For such compositions, metal-sulfide melting will not be complete until a temperature of at least 1350 degrees Centigrade. The silicate solidus for Vesta's composition is between 1100 and 1150 degrees Centigrade, and thus metal and silicate melting must have substantially overlapped in time on Vesta. In this chemically and physically more likely view of Vesta's evolution, metal sulfide drops will sink by Stokes flow through the partially molten silicate magma ocean in a process that can be envisioned as "iron rain". Measurements of eucrites show that moderately siderophile elements such as Ni, Mo, and W reached chemical equilibrium between the metal and silicate phases, which is an important test for any Vesta differentiation model. The equilibration time is a function of the initial metal grain size, which we take to be 25-45 microns based on recent measurements of H6 chondrites. For these sizes and reasonable silicate magma viscosities, equilibration occurs after a fall distance of just a few meters through the magma ocean. Although metal drops may grow in size by merger with other drops, which increases their settling velocities and decreases the total core formation time, the short equilibration distance ensures that the moderately siderophile elements will reach chemical equilibrium between metal and silicate before metal drop merger becomes important. In this model, there must be at least 30 percent melting of the silicate phase when metal melting is complete, corresponding to a crust thickness of at least 30 kilometers on Vesta, consistent with Dawn gravity observations. Greater degrees of silicate melting and a correspondingly thicker crust are possible if Vesta accreted sufficiently rapidly.

The effect of pressure and temperature on sulfur degassing from oxidized magmas: implications for magmatic-hydrothermal ore genesis and "excess sulfur" in volcanic eruptions

NASA Astrophysics Data System (ADS)

Zajacz, Z.

2017-12-01

Sulfur released during the ascent and crystallization of hydrous and oxidized arc magmas is thought to play an essential role in the genesis of magmatic-hydrothermal ore deposits, such as porphyry Cu-Mo-Au and high-sulfidation epithermal Au deposits. If emitted into the atmosphere during volcanic eruptions, it may exert a significant short-term global impact on the Earth's climate due to the generation of sulfate aerosol. Therefore, it is critically important to understand how physical-chemical variables affect the efficiency of sulfur extraction from magmas. High pressure (P) -temperature (T) experiments were conducted to systematically address the effect P-T on the equilibrium partitioning of oxidized sulfur between silicate melts and magmatic volatiles. The confining P was varied between 30 and 480 MPa, whereas the temperature ranged between 920 and 1100 oC. The oxygen fugacity (fO2) was buffered using Re-ReO2 assemblage in all experiments ensuring that sulfur was dominantly present in 4+ and 6+ oxidation state. For the pressure series experiments, a phonolite and a basaltic andesite melt composition was used, because sulfur is thought to be dissolved dominantly as alkali sulfate species in the former and as CaSO4 species in the latter. The data show that the volatile/melt partition coefficients of oxidized sulfur (DSv/m) strongly increase with decreasing pressure for both melt compositions. For example, in the case of the basaltic andesite melt, DSv/m increases from 12.7±0.5 to 71±4 as P changes from 480 to 60 MPa. For the temperature series experiments, the basaltic andesite was replaced by a dacite melt to allow for a broader range of superliquidus temperatures within the reach of the experimental apparatus. The effect of temperature on DSv/m is more moderate than that of P. For the dacite melt, DSv/m dropped by a factor of 2 as temperature decreased from 1100 to 920 oC. The DSv/m values were combined with anhydrite solubility data and implemented in a MELTS model of magma evolution in upper crust. The results of the model calculations suggest that shallower magma emplacement depth is more favorable for effective sulfur extraction by the exsolving volatile phase, and therefore it increases the likelihood of porphyry-ore formation and may lead to larger amounts of "excess sulfur" observed in volcanic eruptions.

Method and apparatus for generating microshells of refractory materials

NASA Technical Reports Server (NTRS)

Lee, Mark C. (Inventor); Schilling, Christopher (Inventor); Ladner, Jr., George O. (Inventor); Wang, Taylor G. (Inventor)

1987-01-01

A system is described for forming accurately spherical and centered fluid-filled shells, especially of high melting temperature material. Material which is to form the shells is placed in a solid form in a container, and the material is rapidly heated to a molten temperature to avoid recrystallization and the possible generation of unwanted microbubbles in the melt. Immediately after the molten shells are formed, they drop through a drop tower whose upper end is heated along a distance of at least one foot to provide time for dissipation of surface waves on the shells while they cool to a highly viscous, or just above melting temperature so that the bubble within the shell will not rise and become off centered. The rest of the tower is cryogenically cooled to cool the shell to a solid state.

Carbonated Eclogite Solidus Between 14 and 20 GPa: Results from the Model CMAS-CO2 System and Contrasting Solidus Behavior to Carbonated Peridotite

NASA Astrophysics Data System (ADS)

Keshav, S.; Gudfinnsson, G. H.

2007-12-01

The carbonate ledge at ~2.0 GPa is a pronounced feature of the carbonated peridotite solidus. At the ledge, where the CO2-bearing phase changes from vapour to carbonate, the melt composition becomes carbonatitic. After this drop, the solidus of carbonated peridotite gradually rises in P-T space, up to at least 12 GPa. Between 14 and 16 GPa, Keshav et al. (2007) reported another drop in the solidus of carbonated peridotite in the model CMS-CO2 system. Similar to the lower-pressure topology, the solidus at higher pressure resumes a positive slope between 16-20 GPa, and seems to flatten between 22 and 26 GPa. Concomitant with this second drop, the melts become extremely calcic (Ca/Ca+Mg, Ca no.-0.62) at 16 and 20 GPa, but attain more magnesio-carbonatitic (Ca no.-0.40) character both at shallower or greater depths than the transition zone. Clearly, the second drop in the carbonated peridotite solidus has tremendous consequences for geological processes in the deep mantle. The other major rock-type presumed to be present in the mantle is eclogite of broadly basaltic composition. Clarifying the solidus topology of carbonated eclogite in model systems over a similar pressure range is also an important task, because the solidus topology affects the fate of subducted carbonate in the deeper mantle. The position of the solidus of carbonated eclogite will address its impact on local or extensive melting (if it occurs), the possible relationship between the carbonated peridotite and carbonated eclogite solidi at these depths (400-600 km), their respective incipient melts, and ultimately the possibility of carbonate survival at these and greater depths. With these issues in mind, we have determined the solidus of model carbonated eclogite in model CMAS- CO2 system between 14 and 20 GPa. At 14 and 16 GPa, the melts are in equilibrium with cpx, majoritic garnet, stishovite, and magnesite. At 20 GPa, the melts are in equilibrium with calcium-perovskite (capv), garnet, stishovite, and magnesite. From average calculated melting reactions along these isobarically univariant curves, stishovite is produced upon melting at all pressures investigated. Significantly, cpx at 14 and 16 GPa and capv at 20 GPa are the dominant contributors toward melt production/composition, in contrast to lower pressures (3-8 GPa) where carbonate dominantly contributes toward melt generation/composition at the solidus. The solidus of model carbonated eclogite at 14, 16, and 20 GPa, lies at 1350, 1450, and 1600 degrees C, respectively, and is nearly linear in P-T space. Melts in equilibrium with all the crystalline phases are highly calcic (Ca no.-0.70), resembling calcio-carbonatites. When magnesite is exhausted from the crystalline assemblage, the melts become slightly less calcic (Ca no.-65). The model carbonated eclogite solidus is always lower than the model carbonated peridotite solidus in the same pressure range. The most remarkable feature of this work is the absence of a drop in the solidus of model carbonated eclogite between 14 and 16 GPa, a result that is in stark contrast to that observed for the model carbonated peridotite at identical pressures. Therefore, even though the solidus temperatures in both carbonated peridotite and eclogite are strongly influenced by the presence of crystalline carbonate, melt compositions and the shape of the solidus in the pressure range investigated seem to be dominantly controlled by the silicate component of the rock in question. Given these results, it is fair to say that a wide range of petrological and geochemical processes operate at these depths in the mantle, and that we have barely scratched the surface in our investigation.

Crystal Nucleation and Growth in Undercooled Melts of Pure Zr, Binary Zr-Based and Ternary Zr-Ni-Cu Glass-Forming Alloys

NASA Astrophysics Data System (ADS)

Herlach, Dieter M.; Kobold, Raphael; Klein, Stefan

2018-03-01

Glass formation of a liquid undercooled below its melting temperature requires the complete avoidance of crystal nucleation and subsequent crystal growth. Even though they are not part of the glass formation process, a detailed knowledge of both processes involved in crystallization is mandatory to determine the glass-forming ability of metals and metallic alloys. In the present work, methods of containerless processing of drops by electrostatic and electromagnetic levitation are applied to undercool metallic melts prior to solidification. Heterogeneous nucleation on crucible walls is completely avoided giving access to large undercoolings. A freely suspended drop offers the additional benefit of showing the rapid crystallization process of an undercooled melt in situ by proper diagnostic means. As a reference, crystal nucleation and dendrite growth in the undercooled melt of pure Zr are experimentally investigated. Equivalently, binary Zr-Cu, Zr-Ni and Zr-Pd and ternary Zr-Ni-Cu alloys are studied, whose glass-forming abilities differ. The experimental results are analyzed within classical nucleation theory and models of dendrite growth. The findings give detailed knowledge about the nucleation-undercooling statistics and the growth kinetics over a large range of undercooling.

Melt migration modeling in partially molten upper mantle

NASA Astrophysics Data System (ADS)

Ghods, Abdolreza

The objective of this thesis is to investigate the importance of melt migration in shaping major characteristics of geological features associated with the partial melting of the upper mantle, such as sea-floor spreading, continental flood basalts and rifting. The partial melting produces permeable partially molten rocks and a buoyant low viscosity melt. Melt migrates through the partially molten rocks, and transfers mass and heat. Due to its much faster velocity and appreciable buoyancy, melt migration has the potential to modify dynamics of the upwelling partially molten plumes. I develop a 2-D, two-phase flow model and apply it to investigate effects of melt migration on the dynamics and melt generation of upwelling mantle plumes and focusing of melt migration beneath mid-ocean ridges. Melt migration changes distribution of the melt-retention buoyancy force and therefore affects the dynamics of the upwelling plume. This is investigated by modeling a plume with a constant initial melt of 10% where no further melting is considered. Melt migration polarizes melt-retention buoyancy force into high and low melt fraction regions at the top and bottom portions of the plume and therefore results in formation of a more slender and faster upwelling plume. Allowing the plume to melt as it ascends through the upper mantle also produces a slender and faster plume. It is shown that melt produced by decompressional melting of the plume migrates to the upper horizons of the plume, increases the upwelling velocity and thus, the volume of melt generated by the plume. Melt migration produces a plume which lacks the mushroom shape observed for the plume models without melt migration. Melt migration forms a high melt fraction layer beneath the sloping base of the impermeable oceanic lithosphere. Using realistic conditions of melting, freezing and melt extraction, I examine whether the high melt fraction layer is able to focus melt from a wide partial melting zone to a narrow region beneath the observed neo-volcanic zone. My models consist of three parts; lithosphere, asthenosphere and a melt extraction region. It is shown that melt migrates vertically within the asthenosphere, and forms a high melt fraction layer beneath the sloping base of the impermeable lithosphere. Within the sloping high melt fraction layer, melt migrates laterally towards the ridge. In order to simulate melt migration via crustal fractures and cracks, melt is extracted from a melt extraction region extending to the base of the crust. Performance of the melt focusing mechanism is not significantly sensitive to the size of melt extraction region, melt extraction threshold and spreading rate. In all of the models, about half of the total melt production freezes beneath the cooling base of the lithosphere, and the rest is effectively focused towards the ridge and forms the crust. To meet the computational demand for a precise tracing of the deforming upwelling plume and including the chemical buoyancy of the partially molten zone in my models, a new numerical method is developed to solve the related pure advection equations. The numerical method is based on Second Moment numerical method of Egan and Mahoney [1972] which is improved to maintain a high numerical accuracy in shear and rotational flow fields. In comparison with previous numerical methods, my numerical method is a cost-effective, non-diffusive and shape preserving method, and it can also be used to trace a deforming body in compressible flow fields.

Dropwise additive manufacturing of pharmaceutical products for melt-based dosage forms.

PubMed

Içten, Elçin; Giridhar, Arun; Taylor, Lynne S; Nagy, Zoltan K; Reklaitis, Gintaras V

2015-05-01

The US Food and Drug Administration introduced the quality by design approach and process analytical technology guidance to encourage innovation and efficiency in pharmaceutical development, manufacturing, and quality assurance. As part of this renewed emphasis on the improvement of manufacturing, the pharmaceutical industry has begun to develop more efficient production processes with more intensive use of online measurement and sensing, real-time quality control, and process control tools. Here, we present dropwise additive manufacturing of pharmaceutical products (DAMPP) as an alternative to conventional pharmaceutical manufacturing methods. This mini-manufacturing process for the production of pharmaceuticals utilizes drop on demand printing technology for automated and controlled deposition of melt-based formulations onto edible substrates. The advantages of drop-on-demand technology, including reproducible production of small droplets, adjustable drop sizing, high placement accuracy, and flexible use of different formulations, enable production of individualized dosing even for low-dose and high-potency drugs. In this work, DAMPP is used to produce solid oral dosage forms from hot melts of an active pharmaceutical ingredient and a polymer. The dosage forms are analyzed to show the reproducibility of dosing and the dissolution behavior of different formulations. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Metastable phase formation in undercooled Fe-Co melts under terrestrial and parabolic flight conditions

NASA Astrophysics Data System (ADS)

Hermann, R.; Löser, W.; Lindenkreuz, H. G.; Yang-Bitterlich, W.; Mickel, Ch.; Diefenbach, A.; Schneider, S.; Dreier, W.

2007-12-01

Soft magnetic Fe-Co alloys display primary fcc phase solidification for>19,5 at% Co in conventional near-equilibrium solidification processes. Undercooled Fe-Co melt drops within the composition range of 30 to 50 at% Co have been investigated with the electromagnetic levitation technique. The solidification kinetics was measured in situ using a high-resolution Siphotodiode. Melt drops were undercooled up to 263 K below the liquidus temperature and subsequently quenched onto a chill substrate in order to characterize the solidification sequence and microstructure. The transition from stable fcc phase to metastable bcc primary phase solidification has been observed after reaching a critical undercooling level. The critical undercooling increases with rising Co content. The growth velocity drops obviously after transition to metastable bcc phase formation. Parabolic flight experiments were performed in order to study the phase selection under reduced gravity conditions. Under microgravity conditions, a much smaller critical undercooling and an increased life time of the metastable bcc phase were obtained. This result was validated with TEM investigations. The appearance of Fe-O particles gives an indirect hint for an intermediate fcc phase formation from the metastable bcc phase at elevated temperature.

Kinetic limit of heterogeneous melting in metals.

PubMed

Ivanov, Dmitriy S; Zhigilei, Leonid V

2007-05-11

The velocity and nanoscale shape of the melting front are investigated in a model that combines the molecular dynamics method with a continuum description of the electron heat conduction and electron-phonon coupling. The velocity of the melting front is strongly affected by the local drop of the lattice temperature, defined by the kinetic balance between the transfer of thermal energy to the latent heat of melting, the electron heat conduction from the overheated solid, and the electron-phonon coupling. The maximum velocity of the melting front is found to be below 3% of the room temperature speed of sound in the crystal, suggesting a limited contribution of heterogeneous melting under conditions of fast heating.

Selective laser melting in heat exchanger development - experimental investigation of heat transfer and pressure drop characteristics of wavy fins

NASA Astrophysics Data System (ADS)

Kuehndel, J.; Kerler, B.; Karcher, C.

2018-04-01

To improve performance of heat exchangers for vehicle applications, it is necessary to increase the air side heat transfer. Selective laser melting gives rise to be applied for fin development due to: i) independency of conventional tooling ii) a fast way to conduct essential experimental studies iii) high dimensional accuracy iv) degrees of freedom in design. Therefore, heat exchanger elements with wavy fins were examined in an experimental study. Experiments were conducted for air side Reynolds number range of 1400-7400, varying wavy amplitude and wave length of the fins at a constant water flow rate of 9.0 m3/h. Heat transfer and pressure drop characteristics were evaluated with Nusselt Number Nu and Darcy friction factor ψ as functions of Reynolds number. Heat transfer and pressure drop correlations were derived from measurement data obtained by regression analysis.

27 CFR 21.99 - Brucine alkaloid.

Code of Federal Regulations, 2011 CFR

2011-04-01

..., characteristic of strychnine, will be obtained. (d) Sulfate test. No white precipitate is formed that is not... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of... tetrahydrate melts at 105 °C. while the anhydrous form melts at 178 °C. (c) Strychnine test. Brucine alkaloid...

27 CFR 21.99 - Brucine alkaloid.

Code of Federal Regulations, 2012 CFR

2012-04-01

..., characteristic of strychnine, will be obtained. (d) Sulfate test. No white precipitate is formed that is not... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of... tetrahydrate melts at 105 °C. while the anhydrous form melts at 178 °C. (c) Strychnine test. Brucine alkaloid...

27 CFR 21.99 - Brucine alkaloid.

Code of Federal Regulations, 2014 CFR

2014-04-01

..., characteristic of strychnine, will be obtained. (d) Sulfate test. No white precipitate is formed that is not... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of... tetrahydrate melts at 105 °C. while the anhydrous form melts at 178 °C. (c) Strychnine test. Brucine alkaloid...

27 CFR 21.99 - Brucine alkaloid.

Code of Federal Regulations, 2013 CFR

2013-04-01

..., characteristic of strychnine, will be obtained. (d) Sulfate test. No white precipitate is formed that is not... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of... tetrahydrate melts at 105 °C. while the anhydrous form melts at 178 °C. (c) Strychnine test. Brucine alkaloid...

27 CFR 21.99 - Brucine alkaloid.

Code of Federal Regulations, 2010 CFR

2010-04-01

..., characteristic of strychnine, will be obtained. (d) Sulfate test. No white precipitate is formed that is not... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of... tetrahydrate melts at 105 °C. while the anhydrous form melts at 178 °C. (c) Strychnine test. Brucine alkaloid...

Experimental Constraints on Silicic Slab Melt and Depleted Mantle Reaction in the Presence of CO2-H2O: Implications for the Origin of Mid Lithospheric Discontinuity

NASA Astrophysics Data System (ADS)

Saha, S.; Dasgupta, R.; Tsuno, K.

2016-12-01

Seismic shear wave velocity, VS drop (upto 24% and mostly 2-7%) observed globally beneath continents at depths of 60-160 km, known as the Mid Lithospheric Discontinuity (MLD) [e.g., 1], is an enigmatic feature of cratons whose origin is highly debated [e.g., 2, 3]. One of the mechanisms that can explain the MLD is the presence of volatile bearing phases such as partial melts and/or hydrous or carbonate minerals at depths. However, the compositional vector and geodynamic scenario required for their formation and the proportion and composition of infiltrating melt or fluid that may lead to their stability is poorly known at present. We performed high P-T experiments equilibrating a depleted peridotite (Mg# 92) with variable proportion of a H2O-CO2 bearing silicic melt, interaction that could occur during the formation of continents by imbrication of slabs. The first set of experiments were performed with 10 wt.% melt (0.9 wt.% H2O and 0.5 wt.% CO2 in the bulk) at 950-1175 °C at 3 GPa using a piston cylinder and 950-1150 °C at 4 GPa using a multi anvil apparatus. Olivine, opx, cpx, garnet/spinel and phlogopite (5-6%) are present in all runs. Amphibole (3.5-9.5%) is present at 3 GPa and ≤1050 °C. Magnesite ( 1%) is present at ≤1000 °C at 3 and ≤1050 °C at 4 GPa. Trace melt is observed along the grain boundaries above 1000 °C at 3 GPa and 1050 ° C at 4 GPa, respectively. Mineral modes obtained by mass balance calculations, ignoring the presence of melts, were used to calculate VS of the resulting assemblages [4]. The calculated drops in VS at 3 GPa (3.8-4.5%) and 4 GPa (1.6-3.2%) are well within the range of velocity drops for MLDs observed globally. Further experiments on different melt-rock ratios are underway and will constrain how modal proportion of hydrous and carbonate minerals varies as a function of melt:rock ratio and bulk volatile contents. [1] Abt et al., 2010, JGR; [2] Rader et al., 2015, G3; [3] Karato et al., 2015, NatGeo [4] Abers & Hacker, 2016, G3

Interaction between tungsten monocarbide and an iron-based metallic melt

NASA Astrophysics Data System (ADS)

Chumanov, I. V.; Anikeev, A. N.

2015-12-01

A technique and results of investigation of compacted tungsten carbide substrates by scanning microscopy are reported. Samples are prepared in the course of studies of the wettability of tungsten carbide substrates with the iron melt, which are performed in accordance with the sessile drop method using two different heating strategies, namely, contact and noncontact heating of metal.

Contact interaction of the Bi12GeO20, Bi12SiO20, and Bi4Ge3O12 melts with noble metals

NASA Astrophysics Data System (ADS)

Denisov, V. M.; Podkopaev, O. I.; Denisova, L. T.; Kuchumova, O. V.; Istomin, S. A.; Pastukhov, E. A.

2014-02-01

The sessile drop method is used to study the contact interaction of Ag, Au, Pd, Pt, and Ir with the Bi2O3-GeO2 and Bi2O3-SiO2 melts. These melts spread over Ag and Pd and, in some cases, over Au and Pt at a rather high speed and form equilibrium contact angles on Ir.

Large charged drop levitation against gravity

NASA Technical Reports Server (NTRS)

Rhim, Won-Kyu; Chung, Sang Kun; Hyson, Michael T.; Trinh, Eugene H.; Elleman, Daniel D.

1987-01-01

A hybrid electrostatic-acoustic levitator that can levitate and manipulate a large liquid drop in one gravity is presented. To the authors' knowledge, this is the first time such large drops (up to 4 mm in diameter in the case of water) have been levitated against 1-gravity. This makes possible, for the first time, many new experiments both in space and in ground-based laboratories, such as 1)supercooling and superheating, 2) containerless crystal growth from various salt solutions or melts, 3) drop dynamics of oscillating or rotating liquid drops, 4) drop evaporation and Rayleigh bursting, and 5) containerless material processing in space. The digital control system, liquid drop launch process, principles of electrode design, and design of a multipurpose room temperature levitation chamber are described. Preliminary results that demonstrate drop oscillation and rotation, and crystal growth from supersaturated salt solutions are presented.

Melt extraction during heating and cooling of felsic crystal mushes in shallow volcanic systems: An experimental study

NASA Astrophysics Data System (ADS)

Pistone, M.; Baumgartner, L. P.; Sisson, T. W.; Bloch, E. M.

2017-12-01

The dynamics and kinetics of melt extraction in near-solidus, rheologically stalled, felsic crystal mushes (> 50 vol.% crystals) are essential to feeding many volcanic eruptions. At shallow depths (< 15 km), most felsic crystal mushes would be volatile-saturated and may be thermally stable for long time periods (104-107 years). In absence of deformation, residual melt can segregate from the mush's crystalline framework stimulated by: 1) gas injecting from hot mafic magmas into felsic mushes (heating / partial melting scenario), and 2) gas exsolving from the crystallizing mush (cooling / crystallizing scenario). The conditions and efficiency of melt extraction from a mush in the two scenarios are not well understood. Thus, we conducted high-temperature (700 to 850 °C) and -pressure (1.1 kbar) cold seal experiments (8-day duration) on synthetic felsic mushes, composed of water-saturated (4.2 wt.%) rhyodacite melt bearing different proportions of added quartz crystals (60, 70, and 80 vol%; 68 mm average particle size). High-spatial resolution X-ray tomography of run products show: 1) in the heating scenario (> 750 °C) melt has not segregated due to coalescence of vesicles (≤ 23 vol%) and large melt connectivity (> 7 vol% glass) / low pressure gradient for melt movement up to 80 vol% crystals; 2) in the cooling scenario (≤ 750 °C) vesicle (< 11 vol%) coalescence is limited or absent and limited amount of melt (3 to 11 vol%) segregated from sample center to its outer periphery (30 to 100 mm melt-rich lenses), testifying to the efficiency of melt extraction dictated by increasing crystallinity. These results suggest that silicic melt hosted within a crystal-rich mush can accumulate rapidly due to the buildup of modest gas pressures during crystallization at temperatures near the solidus.

A large drop in atmospheric [sup 14]C/[sup 12]C and reduced melting in the younger dryas, documented with [sup 230]Th ages of corals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edwards, R.L.; Beck, J.W.; Burr, G.S.

1993-05-14

Paired carbon-14 ([sup 14]C) and thorium-230 ([sup 230]Th) ages were determined on fossil corals from the Huon Peninsula, Papua New Guinea. The ages were used to calibrate part of the [sup 14]C time scale and to estimate rates of sea-level rise during the last deglaciation. An abrupt offset between the [sup 14]C and [sup 230]Th ages suggests that the atmospheric [sup 14]C/[sup 12]C ratio dropped by 15 percent during the latter part of and after the Younger Dryas (YD). This prominent drop coincides with greatly reduced rates of sea-level rise. Reduction of melting because of cooler conditions during the YDmore » may have caused an increase in the rate of ocean ventilation, which caused the atmospheric [sup 14]C/[sup 12]C ratio to fall. The record of sea-level rise also shows that globally averaged rates of melting were relatively high at the beginning of the YD. Thus, these measurements satisfy one of the conditions required by the hypothesis that the diversion of meltwater from the Mississippi to the St. Lawrence River triggered the YD event. 41 refs., 5 figs., 1 tab.« less

The eye of the field geologist and the mind of the tectonician: one view of dynamic crustal rheology in convergent orogens

NASA Astrophysics Data System (ADS)

Brown, M.

2004-05-01

Orogens record evidence of interaction between converging plates. However, the response of continental crust to tectonic and gravitational loads is dependent on rheology, which is influenced by composition, architecture, thermal profile and strain rate. Crustal rocks undergo melting in deeper parts of orogens. Greywackes and metapelites are the most fertile protoliths, generating 20-50 and 30 vol. % melt respectively at 1 GPa and 1173K; geophysical data suggest >6 but <20 vol. % interconnected melt in deep crust of active orogens. In numerical models of orogens, the transition from coupled doubly-vergent wedge structure to plateau formation and full basal decoupling requires a viscosity drop of 4 orders of magnitude, inferred to be melt weakening. Deformation experiments on granite indicate a dramatic drop in strength (to 100-200 MPa) as the melt wetting transition is approached at 7 vol. % melt, and a more gradual decrease to <1 MPa prior to the drop at the solid-to-liquid transition (RCMP). Important properties of melting systems are viscosity of the melt, rheology of the crystalline framework of grains and permeability of this framework to flow. Permeability is due to an intergranular network of connected pores, compositional layering/fabric and networks of deformation bands; melt distribution is heterogeneous on multiple length scales. The microstructure of anatectic rocks and the magnitude of weakening accompanying melting suggest a limited role for intracrystalline plasticity with increasing vol. % melt and dominance of melt-assisted diffusion creep or diffusion accommodated granular flow. The intrinsic weakness of melt-bearing intervals in the crust makes them ideal detachment horizons. Observations from metasedimentary migmatitic granulites show preservation of (i) early fabrics, suggesting that the strain field emergent under subsolidus conditions controlled initial distribution of melt produced by suprasolidus mica breakdown, and (ii) layering in melt-depleted rocks, implying that they were quasi-continuously drained. Studies of migmatitic granulites demonstrate that melt migrates from grain boundaries to mesoscale networks of structures (mm to m) to steeply-inclined conduits recorded by rod or tabular granite intrusions (m to dm). Melt loss from lower crust yields residual rocks composed of strong minerals (feldspar, pyroxene and garnet) with only minor melt on grain boundaries. Thus, weakening of lower crust due to melting is followed by its strengthening. Around the brittle-to-viscous transition zone granite accumulates in subhorizontal tabular plutons, which implies transient presence of significantly weaker layers in shallow orogenic crust; these are potential detachment horizons. Field studies of exhumed orogens suggest deformation commonly is laterally, transversely and vertically diachronous, reflecting the spatial and temporal variation in the weakening-to-strengthening cycle. There may be important sub-horizontal movement horizons, which allow (partial) decoupling of crustal layers. At upper-to-middle crustal levels rocks are metamorphosed in greenschist-amphibolite facies, with local enhancement by pluton-advected heat to amphibolite-granulite facies and thrust-style brittle-ductile deformation (e.g., Acadian, NH). Rocks from middle crustal levels are in amphibolite facies and have penetrative steep fabrics (e.g., Acadian, western ME) or exhibit a complex network of shallowly- and steeply-dipping fabrics (e.g., St. Malo, France). Rocks from lower crustal levels are in amphibolite-granulite facies and have shallow fabrics due to crustal flow, although these may be steepened by later deformation including core-complex formation (e.g., S. Brittany, France).

Petrogenesis of Miller Range 07273, a new type of anomalous melt breccia: Implications for impact effects on the H chondrite asteroid

NASA Astrophysics Data System (ADS)

Ruzicka, Alex M.; Hutson, Melinda; Friedrich, Jon M.; Rivers, Mark L.; Weisberg, Michael K.; Ebel, Denton S.; Ziegler, Karen; Rumble, Douglas; Dolan, Alyssa A.

2017-09-01

Miller Range 07273 is a chondritic melt breccia that contains clasts of equilibrated ordinary chondrite set in a fine-grained (<5 μm), largely crystalline, igneous matrix. Data indicate that MIL was derived from the H chondrite parent asteroid, although it has an oxygen isotope composition that approaches but falls outside of the established H group. MIL also is distinctive in having low porosity, cone-like shapes for coarse metal grains, unusual internal textures and compositions for coarse metal, a matrix composed chiefly of clinoenstatite and omphacitic pigeonite, and troilite veining most common in coarse olivine and orthopyroxene. These features can be explained by a model involving impact into a porous target that produced brief but intense heating at high pressure, a sudden pressure drop, and a slower drop in temperature. Olivine and orthopyroxene in chondrule clasts were the least melted and the most deformed, whereas matrix and troilite melted completely and crystallized to nearly strain-free minerals. Coarse metal was largely but incompletely liquefied, and matrix silicates formed by the breakdown during melting of albitic feldspar and some olivine to form pyroxene at high pressure (>3 GPa, possibly to 15-19 GPa) and temperature (>1350 °C, possibly to ≥2000 °C). The higher pressures and temperatures would have involved back-reaction of high-pressure polymorphs to pyroxene and olivine upon cooling. Silicates outside of melt matrix have compositions that were relatively unchanged owing to brief heating duration.

Research on metal solidification in zero-g state

NASA Technical Reports Server (NTRS)

Papazian, J. M.; Larson, D. J., Jr.

1975-01-01

The containerless solidification of several pure metals and metallic alloys was studied in a low gravity environment. The tests were performed in the MSFC 4.2 s drop tower using a rapid wire melting apparatus designed and built for this purpose. Pure iron and nickel, and alloys of iron-nickel, iron-carbon, nickel-aluminum and tungsten-rhenium were all melted and solidified at a gravity level of approximately 100.000/-4 g. Interpretation of the results has led to an appreciation of the factors controlling the successful execution of this drop test experiment and to a delineation of the limits of applicability of the apparatus. Preliminary metallurgical evaluations are presented of the overall shapes, lattice parameters, surface microstructure,, cross-sectional microstructures, solidification and transformation sequences, evaporative segregation, and localized solute redistribution observed in the low-gravity specimens. The effects of low gravity on metallic solidification are discussed with particular emphasis on observations of spontaneous undercooling and evaporative segregation in uncontained melts.

Ball feeder for replenishing evaporator feed

DOEpatents

Felde, David K.; McKoon, Robert H.

1993-01-01

Vapor source material such as uranium, which is to be dropped into a melt in an evaporator, is made into many balls of identical diameters and placed inside a container. An elongated sloping pipe is connected to the container and leads to the evaporator such that these balls can travel sequentially therealong by gravity. A metering valve in this pipe for passing these balls one at a time is opened in response to a signal when it is ascertained by a detector that there is a ball ready to be passed. A gate in the pipe near the evaporator momentarily stops the motion of the traveling ball and is then opened to allow the ball drop into the melt at a reduced speed.

Ball feeder for replenishing evaporator feed

DOEpatents

Felde, D.K.; McKoon, R.H.

1993-03-23

Vapor source material such as uranium, which is to be dropped into a melt in an evaporator, is made into many balls of identical diameters and placed inside a container. An elongated sloping pipe is connected to the container and leads to the evaporator such that these balls can travel sequentially therealong by gravity. A metering valve in this pipe for passing these balls one at a time is opened in response to a signal when it is ascertained by a detector that there is a ball ready to be passed. A gate in the pipe near the evaporator momentarily stops the motion of the traveling ball and is then opened to allow the ball drop into the melt at a reduced speed.

A TEM analysis of nanoparticulates in a Polar ice core

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esquivel, E.V.; Murr, L.E

2004-03-15

This paper explores the prospect for analyzing nanoparticulates in age-dated ice cores representing times in antiquity to establish a historical reference for atmospheric particulate regimes. Analytical transmission electron microscope (TEM) techniques were utilized to observe representative ice-melt water drops dried down on carbon/formvar or similar coated grids. A 10,000-year-old Greenland ice core was melted, and representative water drops were transferred to coated grids in a clean room environment. Essentially, all particulates observed were aggregates and either crystalline or complex mixtures of nanocrystals. Especially notable was the observation of carbon nanotubes and related fullerene-like nanocrystal forms. These observations are similar withmore » some aspects of contemporary airborne particulates including carbon nanotubes and complex nanocrystal aggregates.« less

Impact of Microorganisms on the Dynamics of Unsaturated Flow Within Fractures

NASA Astrophysics Data System (ADS)

Stoner, D. L.; Stedtfeld, R. D.; Tyler, T. L.; White, F. J.; McJunkin, T. R.

2002-12-01

Understanding the impact of microorganisms on fluid flow in groundwater and subsurface environments is of significance because of the importance of natural water resources, contaminant transport, and in situ bioprocesses such as mineral dissolution and recovery, enhanced oil recovery, and remediation. In this study, the impact of microorganisms and nutrient amendments on the behavior of water within a fracture system was evaluated using an experimental system comprised of limestone blocks and a groundwater isolate, {\\ it Sphingomonas} sp. Four blocks (25 cm x 6.6 cm x 5 cm) were configured to make a vertical fracture (50.2 x 5 x 0.07 cm) that was intersected by a horizontal fracture (13.4 x 5 x 0.1 cm). To monitor the behavior of water within the fracture, 5 optical sensors each consisting of a light emitting diode and photocell were installed external to the vertical fracture. Two were installed above the fracture intersection, two below and one at the intersection. The presence of fluid in the fracture was detected as a decrease in light transmission as the fluid passed by each detector. Drop interval (the period of time between succeeding drops at the same detector) and drop width (the period of time it took for a water drop or stream to pass by each detector) data were collected for each of the five detectors. Liquids were introduced via a single needle at the top of the fracture at a rate of 0.5 ml/min. Deionized water, which had been chemically equilibrated with the limestone rock, was the control medium to which 1) cells; 2) cells with 0.01% yeast extract; 3) cells with 0.1% yeast extract; and 4) cells with 0.1% yeast extract and 30 mM urea were added. For the equilibrated water, drop intervals and drop widths above the fracture intersection were ~1 s and <0.1 s, respectively. Drop intervals and drop widths at and below the intersection were ~100 s and ~10 s, respectively. Above the fracture intersection, the addition of cells or cells with 0.01% yeast extract had little effect on drop intervals and drop widths. At and below the intersection, however, drop intervals increased to ~500 s and drop widths to ~10 s. Later with the addition of 0.1% yeast extract or 0.1% yeast extract with urea, drop interval and drop width immediately increased at locations above the fracture intersection and within 24 hours, continuous streaming was observed. For the lower sensors, drop interval and drop width initially decreased, followed by continuous streaming the day after the 0.1% yeast extract and urea was added to the system. In conclusion, the dynamics of drop behavior in fracture systems is a complex process that is impacted by the presence of bacteria and nutrient amendments as well as the fracture configuration.

The NASA, Marshall Space Flight Center drop tube user's manual

NASA Technical Reports Server (NTRS)

Rathz, Thomas J.; Robinson, Michael B.

1990-01-01

A comprehensive description of the structural and instrumentation hardware and the experimental capabilities of the 105-meter Marshall Space Flight Center Drop Tube Facility is given. This document is to serve as a guide to the investigator who wishes to perform materials processing experiments in the Drop Tube. Particular attention is given to the Tube's hardware to which an investigator must interface to perform experiments. This hardware consists of the permanent structural hardware (with such items as vacuum flanges), and the experimental hardware (with the furnaces and the sample insertion devices). Two furnaces, an electron-beam and an electromagnetic levitator, are currently used to melt metallic samples in a process environment that can range from 10(exp -6) Torr to 1 atmosphere. Details of these furnaces, the processing environment gases/vacuum, the electrical power, and data acquisition capabilities are specified to allow an investigator to design his/her experiment to maximize successful results and to reduce experimental setup time on the Tube. Various devices used to catch samples while inflicting minimum damage and to enhance turnaround time between experiments are described. Enough information is provided to allow an investigator who wishes to build his/her own furnace or sample catch devices to easily interface it to the Tube. The experimental instrumentation and data acquisition systems used to perform pre-drop and in-flight measurements of the melting and solidification process are also detailed. Typical experimental results are presented as an indicator of the type of data that is provided by the Drop Tube Facility. A summary bibliography of past Drop Tube experiments is provided, and an appendix explaining the noncontact temperature determination of free-falling drops is provided. This document is to be revised occasionally as improvements to the Facility are made and as the summary bibliography grows.

Mechanisms and Control of Self-Emulsification upon Freezing and Melting of Dispersed Alkane Drops.

PubMed

Valkova, Zhulieta; Cholakova, Diana; Tcholakova, Slavka; Denkov, Nikolai; Smoukov, Stoyan K

2017-10-31

Emulsification requires drop breakage and creation of a large interfacial area between immiscible liquid phases. Usually, high-shear or high-pressure emulsification devices that generate heat and increase the emulsion temperature are used to obtain emulsions with micrometer and submicrometer droplets. Recently, we reported a new, efficient procedure of self-emulsification (Tcholakova et al. Nat. Commun. 2017, 8, 15012), which consists of one to several cycles of freezing and melting of predispersed alkane drops in a coarse oil-in-water emulsion. Within these freeze-thaw cycles of the dispersed drops, the latter burst spontaneously into hundreds and thousands of smaller droplets without using any mechanical agitation. Here, we clarify the main factors and mechanisms, which drive this self-emulsification process, by exploring systematically the effects of the oil and surfactant types, the cooling rate, and the initial drop size. We show that the typical size of the droplets, generated by this method, is controlled by the size of the structural domains formed in the cooling-freezing stage of the procedure. Depending on the leading mechanism, these could be the diameter of the fibers formed upon drop self-shaping or the size of the crystal domains formed at the moment of drop-freezing. Generally, surfactant tails that are 0-2 carbon atoms longer than the oil molecules are most appropriate to observe efficient self-emulsification. The specific requirements for the realization of different mechanisms are clarified and discussed. The relative efficiencies of the three different mechanisms, as a function of the droplet size and cooling procedure, are compared in controlled experiments to provide guidance for understanding and further optimization and scale-up of this self-emulsification process.

Solidification Dynamics of Spherical Drops in a Free Fall Environment

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Brush, Lucien N.

2006-01-01

Silver drops (99.9%, 4, 5, 7, and 9 mm diameter) were levitated, melted, and released to fall through Marshall Space Flight Center's 105 meter drop tube in helium - 6% hydrogen and pure argon atmospheres. By varying a drop s initial superheat the extent of solidification prior to impact ranged from complete to none during the approx. 4.6s of free fall time. Comparison of the experimental observations is made with numerical solutions to a model of the heat transfer and solidification kinetics associated with cooling of the drop during free fall, particularly with regard to the fraction of liquid transformed. Analysis reveals the relative importance ,of the initial parameters affecting the cooling and solidification rates within the drop. A discussion of the conditions under which the actual observations deviate from the assumptions used in the model is presented.

Solidification Dynamics of Metal Drops in a Free Fall Environment

NASA Technical Reports Server (NTRS)

Grugel, R. N.; Brush, L. N.; Curreri, Peter A. (Technical Monitor)

2001-01-01

Comparison of experimental observations were made with numerical solutions to a model of the heat transfer and solidification kinetics associated with the cooling of a molten drop during free fall, particularly with regard to the fraction of liquid transformed. Experimentally, silver drops (99.9%, 4-9 mm diameter) were levitated, melted, and released to fall through Marshall Space Flight Center's 105m drop tube in helium - 6% hydrogen and argon atmospheres. By systematically varying the drops initial superheat the extent of solidification prior to impact ranged from complete to none during the approximately 4.6s of free fall time. Analysis reveals the relative importance of the initial parameters affecting the cooling and solidification rates within the drop. A discussion of the conditions under which the actual observations deviate from the assumptions used in the model is presented.

Optimisation of gelatin extraction from Unicorn leatherjacket (Aluterus monoceros) skin waste: response surface approach.

PubMed

Hanjabam, Mandakini Devi; Kannaiyan, Sathish Kumar; Kamei, Gaihiamngam; Jakhar, Jitender Kumar; Chouksey, Mithlesh Kumar; Gudipati, Venkateshwarlu

2015-02-01

Physical properties of gelatin extracted from Unicorn leatherjacket (Aluterus monoceros) skin, which is generated as a waste from fish processing industries, were optimised using Response Surface Methodology (RSM). A Box-Behnken design was used to study the combined effects of three independent variables, namely phosphoric acid (H3PO4) concentration (0.15-0.25 M), extraction temperature (40-50 °C) and extraction time (4-12 h) on different responses like yield, gel strength and melting point of gelatin. The optimum conditions derived by RSM for the yield (10.58%) were 0.2 M H3PO4 for 9.01 h of extraction time and hot water extraction of 45.83 °C. The maximum achieved gel strength and melting point was 138.54 g and 22.61 °C respectively. Extraction time was found to be most influencing variable and had a positive coefficient on yield and negative coefficient on gel strength and melting point. The results indicated that Unicorn leatherjacket skins can be a source of gelatin having mild gel strength and melting point.

Dual-polarization characteristics of the radar ocean return in the presence of rain

NASA Technical Reports Server (NTRS)

Meneghini, R.; Kumagai, H.; Kozu, T.

1992-01-01

Experimental data are presented on the polarimetric and dual-wavelength characteristics of the ocean surface in the presence of rain. To explain a portion of the variability observed in scatter plots under rain conditions, a storm model is used that incorporates measured drop size distributions. The fairly large variability indicates that effects of drop size distribution and the presence of partially melted particles can introduce a significant error in the estimate of attenuation. This effect is especially significant in the case of a 10-GHz radar under high rain rates. A surface reference method at this frequency will tend to overestimate the rain attenuation unless melting layer attenuation is properly taken into account. Observations of the cross-polarization return in stratiform rain over an ocean surface show three distinct components. Two of these correspond to aspherical, nonaligned particles in the melting layer seen in the direct and mirror-image returns. The remaining part depends both on the off-nadir depolarization by the surface and on the rain medium. A possible mechanism for this latter effect is the bistatic scattering from the rain to the surface.

Solidification Dynamics of Silver Drops in a Free Fall Environment

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Brush, Lucien N.

1999-01-01

Silver drops (99.9%, 4, 5, 7, and 9 mm diameter) were levitated, melted, and released to fall through Marshall Space Flight Center's 105m drop tube in helium - 6% hydrogen and pure argon atmospheres. By systematically varying the initial superheat condition of the drop the extent of solidification prior to impact ranged from complete to none during the approximately 4.6s of free fall time. Comparison of the experimental observations is made with numerical solutions to a model of the heat transfer and solidification kinetics associated with cooling of the drop during free fall, particularly with regard to the fraction of liquid transformed. Analysis reveals the relative importance of the initial parameters affecting the cooling and solidification rates within the drop. A discussion of the conditions under which the actual observations deviate from the assumptions used in the model is presented.

Spherical crystals of Pb 1 - xSn xTe grown in microgravity

NASA Astrophysics Data System (ADS)

Kinoshita, Kyoichi; Yamada, Tomoaki

1996-07-01

Pb 1- xSn xTe spherical crystals were unintentionally obtained along with a cylindrical Pb 1 - xSn xTe crystal grown during the {SL-J}/{FMPT} mission on board the space shuttle "Endeavor". About 25 spherical crystals ranged from 0.5 to 11 mm in diameter. Melt leaked from the melt reservoir into the spring that plays the role of pushing the melt toward a seed crystal and eliminating free surface areas of the melt. Because of the surface tension of the melt, spherical melt drops formed in the hollow of the spring, then solidified into spherical crystals during the cooling process. Some of the crystals had lower dislocation densities, in the order of 10 4 cm -2, two orders smaller than those of terrestrially grown crystals from a melt. The experiment showed a way of stably positioning a large volume of liquid in microgravity without touching the crucible wall and a way of reducing crystalline defects by such growth.

APPARATUS FOR MELTING AND POURING METAL

DOEpatents

Harris, F.A.

1958-02-25

This patent relates to a crucible for melting and pouring a metal under controlled atmospheric conditions. The crucible has a frangible plug in the bottom and a retaining device to prevent the entrance of the broken portions of the plug into the mold without interfering with the flow of the melt. After the charge has been melted, a knockout rod is lowered through the charge and forced against the frangible plug sufficiently to break off the closure disk along a previously scored line. The disk drops onto a retaining grid large enough to permit the flow of metal around the disk and into the mold below. Thts arrangement elimnates the entry of broken portions of the plug into the mold, thereby elimnating a common cause of imperfect castings.

Numerical Simulation of Hydrodynamics of a Heavy Liquid Drop Covered by Vapor Film in a Water Pool

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, W.M.; Yang, Z.L.; Giri, A.

2002-07-01

A numerical study on the hydrodynamics of a droplet covered by vapor film in water pool is carried out. Two level set functions are used as to implicitly capture the interfaces among three immiscible fluids (melt-drop, vapor and coolant). This approach leaves only one set of conservation equations for the three phases. A high-order Navier-Stokes solver, called Cubic-Interpolated Pseudo-Particle (CIP) algorithm, is employed in combination with level set approach, which allows large density ratios (up to 1000), surface tension and jump in viscosity. By this calculation, the hydrodynamic behavior of a melt droplet falling into a volatile coolant is simulated,more » which is of great significance to reveal the mechanism of steam explosion during a hypothetical severe reactor accident. (authors)« less

Homogeneous freezing of single sulfuric and nitric acid solution drops levitated in an acoustic trap

NASA Astrophysics Data System (ADS)

Diehl, Karoline; Ettner-Mahl, Matthias; Hannemann, Anke; Mitra, Subir K.

2009-10-01

The freezing temperatures of single supercooled drops of binary and ternary sulfuric and nitric acid solutions were measured while varying the acid concentration. An acoustic levitator was used which allows to freely suspend single solution drops in air without electrical charges thereby avoiding any electrical influences which may affect the freezing process. The drops of typically 500 µm in radius were monitored by a video camera during cooling cycles down to - 85 °C to simulate the upper tropospheric and stratospheric temperature range. The present data confirm that liquid solution droplets can be supercooled far below the equilibrium melting point by approximately 35 °C. They follow the general trend of the expected freezing temperatures for homogeneous ice nucleation.

Numerical modelling of lithospheric flexure in front of subduction zones in Japan and its role to initiate melt extraction from the LVZ.

NASA Astrophysics Data System (ADS)

Bessat, A.; Pilet, S.; Duretz, T.; Schmalholz, S. M.

2017-12-01

Petit-spot volcanoes were found fifteen years ago by Japanese researchers at the top of the subducting plate in Japan (Hirano 2006). This discovery is of great significance as it highlights the importance of tectonic processes for the initiation of intraplate volcanism. The location of these small lava flows is unusual and seems to be related to the plate flexure, which may facilitate the extraction of low degree melts from the base of the lithosphere, a hypothesis previously suggested to explain changes in electric and seismic properties at 70-90 km depth, i.e. within the low velocity zone (LVS) (Sifré 2014). A critical question is related to the process associated with the extraction of this low degree melts from the LVZ. First models suggested that extension associated to plate bending allows large cracks to propagate across the lithosphere and could promote the extraction of low degree melts at the base of the lithosphere (Hirano 2006 & Yamamoto 2014). However, the study of petit-spot mantle xenoliths from Japan (Pilet 2016) has demonstrated that low degree melts are not directly extracted to the surface but percolate, interact and metasomatize the oceanic lithosphere. In order to understand the melt extraction process in the region of plate bending, we performed 2D thermo-mechanical simulations of Japanese-type subduction. The numerical model considers viscoelastoplastic deformation. This allows the quantification of state of the stress, strain rates, and viscosities which will control the percolation of melt initially stocked at the base of the lithosphere. Initial results show that plate flexure changes the distribution of the deformation mechanism in the flexure zone, between 40 km to 80 km depth. A change of the dominant deformation mechanism from diffusion creep to dislocation creep and from there to Peierls creep was observed about 200 to 300 km from the trench. These changes are linked to the augmentation of the stresses in the flexure zone. At the base of the lithosphere diffusion creep is observed as a thin layer (20 km), which becomes smaller (10 km) as the subduction progresses in favour of the dislocation creep. Further work will be necessary to prove whether the associated stress distributions is compatible with the development of porosity waves, a critical process to extract melts in low porosity media.

A melting method for RNA extraction from the mucosal membrane of the mouse middle ear.

PubMed

Seo, Young Joon; Kim, Sung Huhn; Moon, In Seok; Choi, Jae Young

2015-03-01

There is much confusion surrounding the methods of RNA extraction from the middle ear mucosa of mice. In this study, we worked to develop a "melting method," which is faster, purer, and more reliable than other methods in common use. Thirty-two ears were used for this study. Light microscopy with hematoxylin-eosin staining of the bullae, scanning electron microscopy (SEM), spectrophotometer analysis, and reverse transcription polymerase chain reaction were performed before and after melting the half lateral bullae, which were detached from the temporal bone by using a lateral retroauricular approach. Each resected half bulla contained a well distributed mucosal membrane. After a TRIzol melting duration of 10-30 minutes, only mucosal marker (MUC5AC) was expressed without bony marker (total osteocalcin). The same results were determined from SEM. This melting method, compared with stripping and irrigation methods, is effective and offers an easier, more robust approach to extracting RNA from the middle ear mucosal membranes of mice.

Effect of сopper сoating on fibers made of aluminum alloy, titanium, and FeCrAl alloy on surface morphology and activity in CO oxidation

NASA Astrophysics Data System (ADS)

Lukiyanchuk, I. V.; Rudnev, V. S.; Serov, M. M.; Krit, B. L.; Lukiyanchuk, G. D.; Nedozorov, P. M.

2018-04-01

The catalytic activity of both copper fibers and copper-coated fibers of a diameter of 50-100 μm made of aluminum alloy, technical grade titanium, and FeCrAl alloy in CO oxidation has been estimated. Metal fibers have been fabricated by the method of pendant drop melt extraction (PDME). The fibers copper plating was carried out by chemical and electrochemical methods. The composition and structure of samples and coatings before and after catalytic tests have been characterized by the methods of scanning electron microscopy, energy-dispersive analysis, and X-ray fluorescence analysis. It has been shown that the catalytic activity of copper-coated fibers made of FeCrAl alloy in the reaction of CO oxidation is not inferior to that of copper fibers.

Coupling geodynamic with thermodynamic modelling for reconstructions of magmatic systems

NASA Astrophysics Data System (ADS)

Rummel, Lisa; Kaus, Boris J. P.; White, Richard

2016-04-01

Coupling geodynamic with petrological models is fundamental for understanding magmatic systems from the melting source in the mantle to the point of magma crystallisation in the upper crust. Most geodynamic codes use very simplified petrological models consisting of a single, fixed, chemistry. Here, we develop a method to better track the petrological evolution of the source rock and corresponding volcanic and plutonic rocks by combining a geodynamic code with a thermodynamic model for magma generation and evolution. For the geodynamic modelling a finite element code (MVEP2) solves the conservation of mass, momentum and energy equations. The thermodynamic modelling of phase equilibria in magmatic systems is performed with pMELTS for mantle-like bulk compositions. The thermodynamic dependent properties calculated by pMELTS are density, melt fraction and the composition of the liquid and solid phase in the chemical system: SiO2-TiO2-Al2O3-Fe2O3-Cr2O3-FeO-MgO-CaO-Na2O-K2O-P2O5-H2O. In order to take into account the chemical depletion of the source rock with increasing melt extraction events, calculation of phase diagrams is performed in two steps: 1) With an initial rock composition density, melt fraction as well as liquid and solid composition are computed over the full upper mantle P-T range. 2) Once the residual rock composition (equivalent to the solid composition after melt extraction) is significantly different from the initial rock composition and the melt fraction is lower than a critical value, the residual composition is used for next calculations with pMELTS. The implementation of several melt extraction events take the change in chemistry into account until the solidus is shifted to such high temperatures that the rock cannot be molten anymore under upper mantle conditions. An advantage of this approach is that we can track the change of melt chemistry with time, which can be compared with natural constraints. In the thermo-mechanical code the thermodynamic dependent properties from pre-computed phase diagrams are carried by each particle using marker-in-cell method . Thus the physical and chemical properties can change locally as a function of previous melt extraction events, pressure and temperature conditions. After each melt extraction event, the residual rock composition is compared with the bulk composition of previous computed phase diagrams, so that the used phase diagram is replaced by the phase diagram with the closest bulk chemistry. In the thermo-mechanical code, the melt is extracted directly to the surface as volcanites and within the crust as plutonites. The density of the crust and new generated crust is calculated with the thermodynamic modelling tool Perple_X. We have investigated the influence of several input parameters on the magma composition to compare it with real rock samples from Eifel (West-Germany). In order to take the very inhomogeneous chemistry of European mantle into account, we include not only primitive mantle but also metasomatised mantle fragments in the melting source of a plume (Eifel plume).

Rapid determination of caffeine in one drop of beverages and foods using drop-to-drop solvent microextraction with gas chromatography/mass spectrometry.

PubMed

Shrivas, Kamlesh; Wu, Hui-Fen

2007-11-02

A simple and rapid sample cleanup and preconcentration method for the quantitative determination of caffeine in one drop of beverages and foods by gas chromatography/mass spectrometry (GC/MS) has been proposed using drop-to-drop solvent microextraction (DDSME). The best optimum experimental conditions for DDSME were: chloroform as the extraction solvent, 5 min extraction time, 0.5 microL exposure volume of the extraction phase and no salt addition at room temperature. The optimized methodology exhibited good linearity between 0.05 and 5.0 microg/mL with correlation coefficient of 0.980. The relative standard deviation (RSD) and limits of detection (LOD) of the DDSME/GC/MS method were 4.4% and 4.0 ng/mL, respectively. Relative recovery of caffeine in beverages and foods were found to be 96.6-101%, which showing good reliability of this method. This DDSME excludes the major disadvantages of conventional method of caffeine extraction, like large amount of organic solvent and sample consumption and long sample pre-treatment process. So, this approach proves that the DDSME/GC/MS technique can be applied as a simple, fast and feasible diagnosis tool for environmental, food and biological application for extremely small amount of real sample analysis.

Separation of rare earths from transition metals by liquid-liquid extraction from a molten salt hydrate to an ionic liquid phase.

PubMed

Rout, Alok; Binnemans, Koen

2014-02-28

The solvent extraction of trivalent rare-earth ions and their separation from divalent transition metal ions using molten salt hydrates as the feed phase and an undiluted fluorine-free ionic liquid as the extracting phase were investigated in detail. The extractant was tricaprylmethylammonium nitrate, [A336][NO3], and the hydrated melt was calcium nitrate tetrahydrate, Ca(NO3)2·4H2O. The extraction behavior of rare-earth ions was studied for solutions of individual elements, as well as for mixtures of rare earths in the hydrated melt. The influence of different extraction parameters was investigated: the initial metal loading in the feed phase, percentage of water in the feed solution, equilibration time, and the type of hydrated melt. The extraction of rare earths from Ca(NO3)2·4H2O was compared with extraction from CaCl2·4H2O by [A336][Cl] (Aliquat 336). The nitrate system was found to be the better one. The extraction and separation of rare earths from the transition metals nickel, cobalt and zinc were also investigated. Remarkably high separation factors of rare-earth ions over transition metal ions were observed for extraction from Ca(NO3)2·4H2O by the [A336][NO3] extracting phase. Furthermore, rare-earth ions could be separated efficiently from transition metal ions, even in melts with very high concentrations of transition metal ions. Rare-earth oxides could be directly dissolved in the Ca(NO3)2·4H2O phase in the presence of small amounts of Al(NO3)3·9H2O or concentrated nitric acid. The efficiency of extraction after dissolving the rare-earth oxides in the hydrated nitrate melt was identical to extraction from solutions with rare-earth nitrates dissolved in the molten phase. The stripping of the rare-earth ions from the loaded ionic liquid phase and the reuse of the recycled ionic liquid were also investigated in detail.

Theoretical Design and Experimental Evaluation of Molten Carbonate Modified LSM Cathode for Low Temperature Solid Oxide Fuel Cells

DTIC Science & Technology

2012-01-01

Li-K binary eutectic salts were prepared for infiltration. Li2CO3 (99%, Alfa Aesar) and K2CO3 (99%, Alfa Aesar) were mixed with a molar ratio of 62:38...99.9%, Alfa Aesar) were also prepared. For infiltration, the eutectic melt was ultrasonic dispersed in ethanol. A few drops of the salt suspension...and heated at 650 oC for 2 h to form a eutectic melt. In addition, eutectic melts containing 0.5 mol % La2O3 (99.9%, Alfa Aesar) or 0.5 mol % Gd2O3

Melting of Cu nanoclusters by molecular dynamics simulation

NASA Astrophysics Data System (ADS)

Wang, Li; Zhang, Yanning; Bian, Xiufang; Chen, Ying

2003-04-01

We present a detailed molecular dynamics study of the melting of copper nanoclusters with up to 8628 atoms within the framework of the embedded-atom method. The finding indicates that there exists an intermediate nanocrystal regime above 456 atoms. The linear relation between the cluster size and its thermodynamics properties is obeyed in this regime. Melting first occurs at the surface of the clusters, leading to Tm, N= Tm,Bulk- αN-1/3, dropping from Tm,Bulk=1360 K to Tm,456=990 K. In addition, the size, surface energy as well as the root mean square displacement (RMSD) of the clusters in the intermediate regime have been investigated.

Kimberlite ascent by assimilation-fuelled buoyancy.

PubMed

Russell, James K; Porritt, Lucy A; Lavallée, Yan; Dingwell, Donald B

2012-01-18

Kimberlite magmas have the deepest origin of all terrestrial magmas and are exclusively associated with cratons. During ascent, they travel through about 150 kilometres of cratonic mantle lithosphere and entrain seemingly prohibitive loads (more than 25 per cent by volume) of mantle-derived xenoliths and xenocrysts (including diamond). Kimberlite magmas also reputedly have higher ascent rates than other xenolith-bearing magmas. Exsolution of dissolved volatiles (carbon dioxide and water) is thought to be essential to provide sufficient buoyancy for the rapid ascent of these dense, crystal-rich magmas. The cause and nature of such exsolution, however, remains elusive and is rarely specified. Here we use a series of high-temperature experiments to demonstrate a mechanism for the spontaneous, efficient and continuous production of this volatile phase. This mechanism requires parental melts of kimberlite to originate as carbonatite-like melts. In transit through the mantle lithosphere, these silica-undersaturated melts assimilate mantle minerals, especially orthopyroxene, driving the melt to more silicic compositions, and causing a marked drop in carbon dioxide solubility. The solubility drop manifests itself immediately in a continuous and vigorous exsolution of a fluid phase, thereby reducing magma density, increasing buoyancy, and driving the rapid and accelerating ascent of the increasingly kimberlitic magma. Our model provides an explanation for continuous ascent of magmas laden with high volumes of dense mantle cargo, an explanation for the chemical diversity of kimberlite, and a connection between kimberlites and cratons.

Investigation of nitrate salts for solar latent heat storage

NASA Astrophysics Data System (ADS)

Kamimoto, M.; Tanaka, T.; Tani, T.; Horigome, T.

1980-01-01

The properties of heat transfer in the discharging of a model solar latent heat storage unit based on various nitrate salts and salt mixtures are investigated. A shell-and-tube-type passive heat exchanger containing NaNO3 or eutectic or off-eutectic mixtures of NaNO3 with KNO3 and Ca(NO3)2 was heated to 40 K above the melting temperature of the salt, when air was made to flow through a heat transfer tube at a constant flow rate, and heat transfer material and air temperatures were monitored. Thermal conductivity and the apparent heat transfer coefficient are estimated from the heat extraction rate and temperature profiles, and it is found that although the thermal conductivities of the materials are similar, the off-eutectic salts exhibit higher heat transfer coefficients. Temperature distributions in the NaNO3-KNO3 mixtures are found to be in fairly good agreement with those predicted by numerical solutions of a one-dimensional finite difference equation, and with approximate analytical solutions. It is observed that the temperature of the heat transfer surface drops rapidly after the appearance of a solid phase, due to the low thermal conductivity of the salts, and means of avoiding this temperature drop are considered.

O the Electrohydrodynamics of Drop Extraction from a Conductive Liquid Meniscus

NASA Astrophysics Data System (ADS)

Wright, Graham Scott

This thesis is concerned with the use of an electric field in the extraction of liquid drops from a capillary orifice or nozzle. The motivating application is ink jet printing. Current drop-on-demand ink jets use pressure pulses to eject drops. Literature on electrostatic spraying suggests that by using an electric field, drops could be produced with a wider range of sizes and speeds than is possible with pressure ejection. Previous efforts to apply electric spraying to printing or similar selective coating tasks have taken an experimental approach based on steady or periodic spraying phenomena, without attempting cycle -by-cycle drop control. The centerpiece of this thesis is a simulation tool developed to explore such possibilities. A simplified analytic model is developed as a preliminary step, yielding formulas for force and time scales that provide an appropriate basis for nondimensionalization of the governing differential equations; important dimensionless parameters are identified. The complete self-consistent model permits simulation of meniscus behavior under time -varying applied voltage or pressure, with the electric field solution continually updated as the surface changes shape. The model uses a quasi-one-dimensional hydrodynamic formulation and a two-dimensional axisymmetric boundary element solution for the electric field. The simulation is checked against experimental results for meniscus stability, resonant modes, and drop emission under electric field. The simulation faithfully captures important qualitative aspects of meniscus behavior and gives reasonable quantitative agreement within the limitations of the model. Insights gained in simulation point the way to a successful laboratory demonstration of drop extraction using a shaped voltage pulse. Drop size control is pursued in simulation using pressure and voltage pulses both alone and in combination, for both light and viscous liquids. Combining pressure and field pulses is shown to be synergistic; drop volumes over a range of 175 to 1 were obtained, while maintaining good drop velocity. The differing strategies for obtaining large and small drops are described. Drop extraction using only the electric field is more difficult, but promising approaches remain open.

Displacement-dispersive liquid-liquid microextraction based on solidification of floating organic drop of trace amounts of palladium in water and road dust samples prior to graphite furnace atomic absorption spectrometry determination.

PubMed

Ghanbarian, Maryam; Afzali, Daryoush; Mostafavi, Ali; Fathirad, Fariba

2013-01-01

A new displacement-dispersive liquid-liquid microextraction method based on the solidification of floating organic drop was developed for separation and preconcentration of Pd(ll) in road dust and aqueous samples. This method involves two steps of dispersive liquid-liquid microextraction based on solidification. In Step 1, Cu ions react with diethyldithiocarbamate (DDTC) to form Cu-DDTC complex, which is extracted by dispersive liquid-liquid microextraction based on a solidification procedure using 1-undecanol (extraction solvent) and ethanol (dispersive solvent). In Step 2, the extracted complex is first dispersed using ethanol in a sample solution containing Pd ions, then a dispersive liquid-liquid microextraction based on a solidification procedure is performed creating an organic drop. In this step, Pd(ll) replaces Cu(ll) from the pre-extracted Cu-DDTC complex and goes into the extraction solvent phase. Finally, the Pd(ll)-containing drop is introduced into a graphite furnace using a microsyringe, and Pd(ll) is determined using atomic absorption spectrometry. Several factors that influence the extraction efficiency of Pd and its subsequent determination, such as extraction and dispersive solvent type and volume, pH of sample solution, centrifugation time, and concentration of DDTC, are optimized.

A fully coupled petrological geodynamical model to investigate the evolution of crustal magma chambers

NASA Astrophysics Data System (ADS)

Rummel, Lisa; Kaus, Boris J. P.; White, Richard W.

2017-04-01

The evolution of crustal magma chambers can be considered from a range of different physical and chemical perspectives. Most previous studies focus either on the petrological side (assuming only thermal effects and ignoring mechanics), or on the mechanical evolution (assuming a fixed melt chemistry). Here, we develop a method that fully couples petrological with geodynamic modelling, by combining a finite element code, MVEP2, with a thermodynamic modelling approach (Perple_X) that takes the evolving chemistry into account. The evolution of melt chemistry in a crustal magma chamber is analyzed by focusing on the effects of depth and temperature as well as size and shape of the magma chamber(s). The models show that each of these factors influences the melting behavior of rocks, the magma composition and their effects on the mechanics in the upper lithosphere. Interactions with country rocks (assimilation), ongoing rock depletion (fractional melting) and a possible open system behavior (fractional crystallization) and their effects on magma chemistry are taken into account. The chemical and mineralogical evolution of the melt source, composition (10 oxide component system) of intrusive and extrusive rocks as well as melt fraction and density are tracked on particles using a marker-in-cell-method in the geodynamic code. After each melt extraction event, the employed phase diagram is updated or recalculated based on the residuum chemistry that shifts the solidus to higher temperatures with sequential melt extraction. The resulting wide range in chemical compositions and the volume of intrusive and extrusive rocks are tracked in time and space over the melting region. The newly generated crust employs phase diagrams which are directly computed from the chemistry of extracted melts. Plutons are able to melt again as long as the local temperature is higher in the model than the solidus temperature in the employed phase diagram. As a result, our models make testable predictions on types of erupted lavas. We show an application to the plume-related intracontinental West Eifel volcanism (Germany), where our models explain a sudden change in K2O/Na2O-ratios in the volcanic rocks by a transition between melting a metasomatized and a pyrolitic mantle. We also show initial results from crustal melt extraction in an arc system.

Acoustic containerless experiment system: A non-contact surface tension measurement

NASA Technical Reports Server (NTRS)

Elleman, D. D.; Wang, T. G.; Barmatz, M.

1988-01-01

The Acoustic Containerless Experiment System (ACES) was flown on STS 41-B in February 1984 and was scheduled to be reflown in 1986. The primary experiment that was to be conducted with the ACES module was the containerless melting and processing of a fluoride glass sample. A second experiment that was to be conducted was the verification of a non-contact surface tension measurement technique using the molten glass sample. The ACES module consisted of a three-axis acoustic positioning module that was inside an electric furnace capable of heating the system above the melting temperature of the sample. The acoustic module is able to hold the sample with acoustic forces in the center of the chamber and, in addition, has the capability of applying a modulating force on the sample along one axis of the chamber so that the molten sample or liquid drop could be driven into one of its normal oscillation modes. The acoustic module could also be adjusted so that it could place a torque on the molten drop and cause the drop to rotate. In the ACES, a modulating frequency was applied to the drop and swept through a range of frequencies that would include the n = 2 mode. A maximum amplitude of the drop oscillation would indicate when resonance was reached and from that data the surface tension could be calculated. For large viscosity samples, a second technique for measuring surface tension was developed. The results of the ACES experiment and some of the problems encountered during the actual flight of the experiment will be discussed.

Characteristic properties of laser ablation of translucent targets

NASA Astrophysics Data System (ADS)

Platonov, V. V.; Kochurin, E. A.; Osipov, V. V.; Lisenkov, V. V.; Zubarev, N. M.

2018-07-01

This study reveals the characteristic features of the laser ablation of the solid Nd:Y2O3 targets, such as the dynamics of the laser plume, the crater depth, and the weight and size distribution of liquid melt droplets. The ablation was initiated by the ytterbium fiber laser radiation pulses with constant energy (0.67 J) and with different power densities. The dependence on the power density of such parameters as the injection time of drops, mass distribution of drops, crater depth, and productivity of synthesis of nonopowder was revealed. To explain the formation of deep craters a model was proposed, stating that the formation of liquid droplets is a consequence of the Kelvin–Helmholtz instability’s appearing and developing on the border between the liquid melt on the crater’s wall and the vapor flow from the crater. The increment of this instability and its characteristic size was determined.

Unlabeled oligonucleotides as internal temperature controls for genotyping by amplicon melting.

PubMed

Seipp, Michael T; Durtschi, Jacob D; Liew, Michael A; Williams, Jamie; Damjanovich, Kristy; Pont-Kingdon, Genevieve; Lyon, Elaine; Voelkerding, Karl V; Wittwer, Carl T

2007-07-01

Amplicon melting is a closed-tube method for genotyping that does not require probes, real-time analysis, or allele-specific polymerase chain reaction. However, correct differentiation of homozygous mutant and wild-type samples by melting temperature (Tm) requires high-resolution melting and closely controlled reaction conditions. When three different DNA extraction methods were used to isolate DNA from whole blood, amplicon Tm differences of 0.03 to 0.39 degrees C attributable to the extractions were observed. To correct for solution chemistry differences between samples, complementary unlabeled oligonucleotides were included as internal temperature controls to shift and scale the temperature axis of derivative melting plots. This adjustment was applied to a duplex amplicon melting assay for the methylenetetrahydrofolate reductase variants 1298A>C and 677C>T. High- and low-temperature controls bracketing the amplicon melting region decreased the Tm SD within homozygous genotypes by 47 to 82%. The amplicon melting assay was 100% concordant to an adjacent hybridization probe (HybProbe) melting assay when temperature controls were included, whereas a 3% error rate was observed without temperature correction. In conclusion, internal temperature controls increase the accuracy of genotyping by high-resolution amplicon melting and should also improve results on lower resolution instruments.

Constant average olivine Mg# in cratonic mantle reflects Archaean mantle melting to the exhaustion of orthopyroxene

NASA Astrophysics Data System (ADS)

Bernstein, S.; Kelemen, P. B.; Hanghoj, K.

2006-12-01

Shallow (garnet-free) cratonic mantle, occurring as xenoliths in kimberlites and alkaline basaltic lavas, has high Mg# (100x Mg/(Mg+Fe)>92) and is poor in Al and Ca compared to off-cratonic mantle. Many xenoliths show rhenium-depletion age of > 3 Ga, and are thus representative of depleted mantle peridotite that form an integral part of the stable nuclei of Archaean (2.5-3.8 Ga) cratons. Accordingly, the depleted composition of the xenolith suites is linked to Archaean melt extraction events. We have compiled data for many suites of shallow cratonic mantle xenoliths worldwide, including samples from cratons of Kaapvaal, Tanzania, Siberia, Slave, North China and Greenland, and encompassing both the classic orthopyroxene-rich peridotites of Kaapvaal and orthopyroxene-poor peridotites from Greenland. The suites show a remarkably small range in average olivine Mg# of 92.8 +/- 0.2. Via comparison with data for experimental melting of mantle peridotite compositions, we explain consistent olivine Mg# in the shallow cratonic mantle as the result of mantle melting and melt extraction to the point of orthopyroxene exhaustion, leaving a nearly monomineralic olivine, or dunitic, residue. Experimental data for peridotite melting at pressures less than 4 GPa and data on natural rocks suggest that mantle olivine has a Mg# of about 92.8 at the point of orthopyroxene exhaustion. If the melt extraction was efficient, no further melting could take place without a considerable temperature increase or melt/fluid flux through the dunite residue at high temperatures. While the high Mg#, dunite-dominated xenolith suites from e.g. Greenland represent simple residues from mantle melting, the orthopyroxene-rich xenolith suites with identical Mg# as known from e. g. Kaapvaal must reflect some additional processes. We envisage their derivation from dunite protoliths via subsequent melt/rock reaction with silica-rich melts or, in some cases, possibly as residues at higher average melting pressures.

Susceptibility measurements on the superconducting properties of Nb-Ge alloys

NASA Technical Reports Server (NTRS)

Rathz, T. J.

1981-01-01

A susceptibility apparatus to measure superconducting properties of samples made in the MSFC Drop Tube was used to measure the transition temperature (Tc) and susceptibilities of Nb and Nb Ge Alloys prepared in bulk spherical (2-4 mm diameter) form using a 32 m drop tube in which containerless low gravity solidification could take place. Results indicate that a drop tube processing environment was beneficial for increasing the Tc of the superconducting phase of the material over that of arc melted material. The increase in Tc is found to be related to the amount of solidification of the total sample that took place before reaching the bottom of the drop tube. In phase and quadrature phase measurements of the specimen's susceptibility indicated that some improvement in homogeneity takes place in drop tube processing. These phase measurements also indicated little or no shielding of a lower Tc phase by a higher Tc filamentary structure.

Charged Water Droplets can Melt Metallic Electrodes

NASA Astrophysics Data System (ADS)

Elton, Eric; Rosenberg, Ethan; Ristenpart, William

2016-11-01

A water drop, when immersed in an insulating fluid, acquires charge when it contacts an energized electrode. Provided the electric field is strong enough, the drop will move away to the opposite electrode, acquire the opposite charge, and repeat the process, effectively 'bouncing' back and forth between the electrodes. A key implicit assumption, dating back to Maxwell, has been that the electrode remains unaltered by the charging process. Here we demonstrate that the electrode is physically deformed during each charge transfer event with an individual water droplet or other conducting object. We used optical, electron, and atomic force microscopy to characterize a variety of different metallic electrodes before and after drops were electrically bounced on them. Although the electrodes appear unchanged to the naked eye, the microscopy reveals that each charge transfer event yielded a crater approximately 1 micron wide and 50 nm deep, with the exact dimensions proportional to the applied field strength. We present evidence that the craters are formed by localized melting of the electrodes via Joule heating in the metal and concurrent dielectric breakdown of the surrounding fluid, suggesting that the electrode locally achieves temperatures exceeding 3400°C. Present address: Dept. Materials Sci. Engineering, MIT.

Pre-Harvest Dropped Kinnow ( Citrus reticulata Blanco) Waste Management through the Extraction of Naringin and Pectin from their Peels using Indigenous Resin

NASA Astrophysics Data System (ADS)

Laxmi Deepak Bhatlu, M.; Katiyar, Prashant; Singh, Satya Vir; Verma, Ashok Kumar

2016-09-01

About 10-20 % kinnow fruits are dropped in preharvest stage which are waste and are problem to farmer as these create nuisance by rotting and insect rearing ground. The peels of these dropped fruits as well as peels from kinnow processing may be good source of naringin and pectin. Naringin is used in pharmaseutics while pectin is used in food industry. For recovery of naringin and pectn, peels of preharvest dropped kinnow fruits were boiled in water. The extract was passed through macroporus polymeric adsorbent resin Indion PA 800, naringin was adsorbed on it. The adsorbed naringin was desorbed with ethanol. This solution was passed through membrane filter and filtrate was evaporated to obtain naringin. The extract remaining after adsorption of naringin was used to recover pectin using acid extraction method. The recovery of naringin and pectin was about 52 and 58 % respectively. The naringin finally obtained had 91-93 % purity.

Desiccation and freezing tolerance of embryonic axes from Citrus sinensis [L.] osb. pretreated with sucrose.

PubMed

Santos, Izulmé R I; Stushnoff, Cecil

2003-01-01

Embryonic axes of Citrus sinensis L. were successfully cryopreserved. While fully hydrated unfrozen axes germinated 100%, survival decreased as axes water content dropped, and total loss of viability was observed when the water content dropped to 0.04 and 0.10 mg H2O/mg dry mass, for axes without and with sucrose preculture, respectively. Fully hydrated axes did not survive exposure to liquid nitrogen. Highest seedling recovery (93-100%) for untreated axes was observed at 0.26 to 0.15 mg H2O/mg dry mass. Differential scanning calorimetry revealed the presence of broad melting peaks in fully hydrated embryonic axes. The size of the melting peak diminished as water was removed by desiccation. Minimum melting of water was observed at the point axes survived cryopreservation. Occurrence of a glass transition upon warming was not a condition for axes to survive liquid nitrogen exposure. In untreated axes, glucose, increased with desiccation to 0.2 mg H2O/mg dry mass, and decreased as the axes were desiccated to lower water contents. Fructose and sucrose levels did not increase when untreated samples were desiccated for the same periods of time. Raffinose and stachyose levels decreased as untreated and precultured embryonic axes were desiccated. In sucrose precultured axes, sucrose and fructose levels increased when they were dehydrated, reaching maximum levels at 0.2 mg H2O/mg dry mass. Tissue glucose did not change significantly with desiccation. Raffinose and stachyose levels dropped as precultured embryonic axes were dried.

Interaction of exogenous refractory nanophases with antimony dissolved in liquid iron

NASA Astrophysics Data System (ADS)

Burtsev, V. T.; Anuchkin, S. N.; Samokhin, A. V.

2017-07-01

The heterophase interaction of Al2O3 refractory nanoparticles with a surfactant impurity (antimony) in the Fe-Sb (0.095 wt %)-O (0.008 wt %) system is studied. It is shown that the introduction of 0.06-0.18 wt % Al2O3 nanoparticles (25-83 nm) into a melt during isothermal holding for up to 1200 s leads to a decrease in the antimony content: the maximum degree of antimony removal is 26 rel %. The sessile drop method is used to investigate the surface tension and the density of Fe, Fe-Sb, and Fe-Sb-Al2O3 melts. The polytherms of the surface tension of these melts have a linear character, the removal of antimony from the Fe-Sb-Al2O3 melts depends on the time of melting in a vacuum induction furnace, and the experimental results obtained reveal the kinetic laws of the structure formation in the surface layers of the melts. The determined melt densities demonstrate that the introduction of antimony into the Fe-O melt causes an increase in its compression by 47 rel %. The structure of the Fe-Sb-O melt after the introduction of Al2O3 nanoparticles depends on the time of melting in a vacuum induction furnace.

Evaluation of Surface and Near-Surface Melt Characteristics on the Greenland Ice Sheet using MODIS and QuikSCAT Data

NASA Technical Reports Server (NTRS)

Hall, Dorothy K.; Nghiem, Son V.; Schaaf, Crystal B.; DiGirolamo, Nicolo E.

2009-01-01

The Greenland Ice Sheet has been the focus of much attention recently because of increasing melt in response to regional climate warming. To improve our ability to measure surface melt, we use remote-sensing data products to study surface and near-surface melt characteristics of the Greenland Ice Sheet for the 2007 melt season when record melt extent and runoff occurred. Moderate Resolution Imaging Spectroradiometer (MODIS) daily land-surface temperature (LST), MODIS daily snow albedo, and a special diurnal melt product derived from QuikSCAT (QS) scatterometer data, are all effective in measuring the evolution of melt on the ice sheet. These daily products, produced from different parts of the electromagnetic spectrum, are sensitive to different geophysical features, though QS- and MODIS-derived melt generally show excellent correspondence when surface melt is present on the ice sheet. Values derived from the daily MODIS snow albedo product drop in response to melt, and change with apparent grain-size changes. For the 2007 melt season, the QS and MODIS LST products detect 862,769 square kilometers and 766,184 square kilometers of melt, respectively. The QS product detects about 11% greater melt extent than is detected by the MODIS LST product probably because QS is more sensitive to surface melt, and can detect subsurface melt. The consistency of the response of the different products demonstrates unequivocally that physically-meaningful melt/freeze boundaries can be detected. We have demonstrated that these products, used together, can improve the precision in mapping surface and near-surface melt extent on the Greenland Ice Sheet.

Microgravity

NASA Image and Video Library

2001-01-24

A 3 mm-diameter droplet of aluminum oxide, heated to 2371 deg. C (4,300 deg. F), is suspended in midair by six acoustic transducers. A gas jet (from the nozzle below the drop) helps position the drop for study, and a 500-watt laser melts the sample. Glasses made from aluminum oxide are highly promising for optical transmission and other properties. They are also highly reactive when molten. Containerless processing allows studies of how to form amorphous (glassy) rather than crystalline metal oxides. Credit: Bill Jellison, Containerless Research, Inc.

An experimental study of steam explosions involving chemically reactive metal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, D.H.; Armstrong, D.R.; Gunther, W.H.

1997-07-01

An experimental study of molten zirconium-water explosions was conducted. A 1-kg mass of zirconium melt was dropped into a column of water. Explosions took place only when an external trigger was used. In the triggered tests, the extent of oxidation of the zirconium melt was very extensive. However, the explosion energetics estimated were found to be very small compared to the potential chemical energy available from the oxidation reaction. Zirconium is of particular interest, since it is a component of the core materials of the current nuclear power reactors. This paper describes the test apparatus and summarizes the results ofmore » four tests conducted using pure zirconium melt.« less

Utilization of Space Shuttle External Tank materials by melting and powder metallurgy

NASA Technical Reports Server (NTRS)

Chern, T. S.

1985-01-01

The Crucible Melt Extraction Process was demonstrated to convert scraps of aluminum alloy 2219, used in the Space Shuttle External Tank, into fibers. The cast fibers were then consolidated by cold welding. The X-ray diffraction test of the cast fibers was done to examine the crystallinity and oxide content of the fibers. The compressive stress-strain behavior of the consolidated materials was also examined. Two conceptual schemes which would adapt the as-developed Crucible Melt Extraction Process to the microgravity condition in space were finally proposed.

Utilization of space shuttle external tank materials by melting and powder metallurgy

NASA Astrophysics Data System (ADS)

Chern, Terry S.

The Crucible Melt Extraction Process was demonstrated to convert scraps of aluminum alloy 2219, used in the Space Shuttle External Tank, into fibers. The cast fibers were then consolidated by cold welding. The X-ray diffraction test of the cast fibers was done to examine the crystallinity and oxide content of the fibers. The compressive stress-strain behavior of the consolidated materials was also examined. Two conceptual schemes which would adapt the as-developed Crucible Melt Extraction Process to the microgravity condition in space were finally proposed.

Suitable conditions for liquid-phase microextraction using solidification of a floating drop for extraction of fat-soluble vitamins established using an orthogonal array experimental design.

PubMed

Sobhi, Hamid Reza; Yamini, Yadollah; Esrafili, Ali; Abadi, Reza Haji Hosseini Baghdad

2008-07-04

A simple, rapid and efficient microextraction method for the extraction and determination of some fat-soluble vitamins (A, D2, D3) in aqueous samples was developed. For the first time orthogonal array designs (OADs) were employed to screen the liquid-phase microextraction (LPME) method in which few microliters of 1-undecanol were delivered to the surface of the aqueous sample and it was agitated for a selected time. Then sample vial was cooled by inserting it into an ice bath for 5 min. The solidified solvent was transferred into a suitable vial and immediately melted. Then, the extract was directly injected into a high-performance liquid chromatography (HPLC) for analysis. Several factors affecting the microextraction efficiency such as sample solution temperature, stirring speed, volume of the organic solvent, ionic strength and extraction time were investigated and screened using an OA16 (4(5)) matrix. Under the best conditions (temperature, 55 degrees C; stirring speed, 1000 rpm; the volume of extracting solvent, 15.0 microL; no salt addition and extraction time, 60 min), detection limits of the method were in the range of 1.0-3.5 microgL(-1). The relative standard deviations (RSDs) to determine the vitamins at microg L(-1) levels by applying the proposed method varied in the range of 5.1-10.7%. Dynamic linear ranges of 5-500 mugL(-1) with good correlation coefficients (0.9984

Rapid pretreatment and determination of bisphenol A in water samples based on vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection.

PubMed

Yang, Xiao; Diao, Chun-Peng; Sun, Ai-Ling; Liu, Ren-Min

2014-10-01

A method for the rapid pretreatment and determination of bisphenol A in water samples based on vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection was proposed in this paper. A simple apparatus consisting of a test tube and a cut-glass dropper was designed and applied to collect the floating extraction drop in liquid-liquid microextraction when low-density organic solvent was used as the extraction solvent. Solidification and melting steps that were tedious but necessary once the low-density organic solvent used as extraction solvent could be avoided by using this apparatus. Bisphenol A was selected as model pollutant and vortex-assisted liquid-liquid microextraction was employed to investigate the usefulness of the apparatus. High-performance liquid chromatography with fluorescence detection was selected as the analytical tool for the detection of bisphenol A. The linear dynamic range was from 0.10 to 100 μg/L for bisphenol A, with good squared regression coefficient (r(2) = 0.9990). The relative standard deviation (n = 7) was 4.7% and the limit of detection was 0.02 μg/L. The proposed method had been applied to the determination of bisphenol A in natural water samples and was shown to be economical, fast, and convenient. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Crystallization kinetics in Si-1 at%Sn during rapid solidification in undercooled melt

NASA Astrophysics Data System (ADS)

Kuribayashi, K.; Ozawa, S.; Nagayama, K.; Inatomi, Y.

2017-06-01

In order to elucidate the cause of the morphological transition of crystals growing in an undercooled melt of semiconducting materials, we carried out the containerless solidification of undoped Si and Si-1 at%Sn using a CO2 laser-equipped electromagnetic levitator (EML). The crystallization of these materials was successfully achieved under controlled undercooling. The relation between the shape of growing crystals and the degree of undercooling in Si-1 at%Sn was similar to that in undoped Si; that is, plate-like needle crystals were observed at low undercooling, whereas at medium and high undercooling the shape of growing crystals changed to massive dendrites. The grain-size of as-solidified samples of Si-1 at%Sn was remarkably small compared with that of undoped Si. The surface morphologies of samples solidified by dropping the melt onto a chill plate of mirror-polished silicon consisted of typical twin-related <110> dendrites. On the other hand, samples that were dropped from the undercooled state consisted of twin-free <100> dendrites. The nucleation rate of two-dimensional nuclei calculated on the basis of two mechanisms, which are the twin-plane re-entrant edge mechanism and the twin-free mechanism, suggested that the morphological transition to twin-free <100> dendrites from twin-related <110> dendrites occurs when the degree of undercooling becomes larger than the critical value. These results indicate that the cause of the morphological transition of Si growing in the undercooled melt is not the roughening transition of the crystal-melt interface but the transition of the nucleation kinetics to the twin-free mechanism from the twin-related mechanism.

Prebiotic chemistry in clouds

NASA Technical Reports Server (NTRS)

Oberbeck, Verne R.; Marshall, John; Shen, Thomas

1991-01-01

The chemical evolution hypothesis of Woese (1979), according to which prebiotic reactions occurred rapidly in droplets in giant atmospheric reflux columns was criticized by Scherer (1985). This paper proposes a mechanism for prebiotic chemistry in clouds that answers Scherer's concerns and supports Woese's hypothesis. According to this mechanism, rapid prebiotic chemical evolution was facilitated on the primordial earth by cycles of condensation and evaporation of cloud drops containing clay condensation nuclei and nonvolatile monomers. For example, amino acids supplied by, or synthesized during entry of meteorites, comets, and interplanetary dust, would have been scavenged by cloud drops containing clay condensation nuclei and would be polymerized within cloud systems during cycles of condensation, freezing, melting, and evaporation of cloud drops.

Physical Phenomena in Containerless Glass Processing

NASA Technical Reports Server (NTRS)

Subramanian, R. S.; Cole, R.

1985-01-01

An investigation into the various physical phenomena of importance in the space experiments is under way. Theoretical models of thermocapillary flow in drops, thermal migration of bubbles and droplets, the motion of bubbles inside drops, and the migration of bubbles in rotating liquid bodies are being developed. Experiments were conducted on the migration of bubbles and droplets to the axis of a rotating liquid body, and the rise of bubbles in molten glass. Also, experiments on thermocapillary motion in silicone oils as well as glass melts were performed. Experiments are currently being conducted on the migration of bubbles in a thermal gradient, and on their motion inside unconstrained liquid drops in a rotating liquid.

Unlabeled Oligonucleotides as Internal Temperature Controls for Genotyping by Amplicon Melting

PubMed Central

Seipp, Michael T.; Durtschi, Jacob D.; Liew, Michael A.; Williams, Jamie; Damjanovich, Kristy; Pont-Kingdon, Genevieve; Lyon, Elaine; Voelkerding, Karl V.; Wittwer, Carl T.

2007-01-01

Amplicon melting is a closed-tube method for genotyping that does not require probes, real-time analysis, or allele-specific polymerase chain reaction. However, correct differentiation of homozygous mutant and wild-type samples by melting temperature (Tm) requires high-resolution melting and closely controlled reaction conditions. When three different DNA extraction methods were used to isolate DNA from whole blood, amplicon Tm differences of 0.03 to 0.39°C attributable to the extractions were observed. To correct for solution chemistry differences between samples, complementary unlabeled oligonucleotides were included as internal temperature controls to shift and scale the temperature axis of derivative melting plots. This adjustment was applied to a duplex amplicon melting assay for the methylenetetrahydrofolate reductase variants 1298A>C and 677C>T. High- and low-temperature controls bracketing the amplicon melting region decreased the Tm SD within homozygous genotypes by 47 to 82%. The amplicon melting assay was 100% concordant to an adjacent hybridization probe (HybProbe) melting assay when temperature controls were included, whereas a 3% error rate was observed without temperature correction. In conclusion, internal temperature controls increase the accuracy of genotyping by high-resolution amplicon melting and should also improve results on lower resolution instruments. PMID:17591926

Purification of melt-spun metallurgical grade silicon micro-flakes through a multi-step segregation procedure

NASA Astrophysics Data System (ADS)

Martinsen, F. A.; Nordstrand, E. F.; Gibson, U. J.

2013-01-01

Melt-spun metallurgical grade (MG) micron dimension silicon flakes have been purified into near solar grade (SG) quality through a multi-step melting and re-solidification procedure. A wet oxidation-applied thermal oxide maintained the sample morphology during annealing while the interiors were melted and re-solidified. The small thickness of the flakes allowed for near elimination of in-plane grain boundaries, with segregation enhanced accumulation of impurities at the object surface and in the few remaining grain boundaries. A subsequent etch in 48% hydrofluoric acid (HF) removed the impure oxide layer, and part of the contamination at the oxide-silicon interface, as shown by electron dispersive spectroscopy (EDS) and backscattered electron imaging (BEI). The sample grains were investigated by electron back-scattered diffraction (EBSD) after varying numbers of oxidation-annealing-etch cycles, and were observed to grow from ˜5 μm to ˜200 μm. The concentration of iron, titanium, copper and aluminium were shown by secondary ion mass spectroscopy (SIMS) and inductively coupled plasma mass spectroscopy (ICPMS) to drop between five and six orders of magnitude. The concentration of boron was observed to drop approximately one order of magnitude. A good correlation was observed between impurity removal rates and segregation models, indicating that the purification effect is mainly caused by segregation. Deviations from these models could be explained by the formation of oxides and hydroxides later removed through etching.

A thermodynamical model for the surface tension of silicate melts in contact with H2O gas

USGS Publications Warehouse

Colucci, Simone; Battaglia, Maurizio; Trigila, Raffaello

2016-01-01

Surface tension plays an important role in the nucleation of H2O gas bubbles in magmatic melts and in the time-dependent rheology of bubble-bearing magmas. Despite several experimental studies, a physics based model of the surface tension of magmatic melts in contact with H2O is lacking. This paper employs gradient theory to develop a thermodynamical model of equilibrium surface tension of silicate melts in contact with H2O gas at low to moderate pressures. In the last decades, this approach has been successfully applied in studies of industrial mixtures but never to magmatic systems. We calibrate and verify the model against literature experimental data, obtained by the pendant drop method, and by inverting bubble nucleation experiments using the Classical Nucleation Theory (CNT). Our model reproduces the systematic decrease in surface tension with increased H2O pressure observed in the experiments. On the other hand, the effect of temperature is confirmed by the experiments only at high pressure. At atmospheric pressure, the model shows a decrease of surface tension with temperature. This is in contrast with a number of experimental observations and could be related to microstructural effects that cannot be reproduced by our model. Finally, our analysis indicates that the surface tension measured inverting the CNT may be lower than the value measured by the pendant drop method, most likely because of changes in surface tension controlled by the supersaturation.

Magmatic controls on the genesis of porphyry Cu-Mo-Au deposits: The Bingham Canyon example

NASA Astrophysics Data System (ADS)

Grondahl, Carter; Zajacz, Zoltán

2017-12-01

Bingham Canyon is one of the world's largest porphyry Cu-Mo-Au deposits and was previously used as an example to emphasize the role of magma mixing and magmatic sulphide saturation in the enhancement of ore fertility of magmatic systems. We analyzed whole rocks, minerals, and silicate melt inclusions (SMI) from the co-genetic, ore-contemporaneous volcanic package (∼38 Ma). As opposed to previous propositions, whole-rock trace element signatures preclude shoshonite-latite genesis via mixing of melanephelinite and trachyte or rhyolite, whereas core to rim compositional profiles of large clinopyroxene phenocrysts suggests the amalgamation of the ore-related magma reservoir by episodic recharge of shoshonitic to latitic magmas with various degrees of differentiation. Major and trace element and Sr and Nd isotopic signatures indicate that the ore-related shoshonite-latite series were generated by low-degree partial melting of an ancient metasomatized mantle source yielding volatile and ore metal rich magmas. Latite and SMI compositions can be reproduced by MELTS modeling assuming 2-step lower and upper crustal fractionation of a primary shoshonite with minimal country rock assimilation. High oxygen fugacities (≈ NNO + 1) are prevalent as evidenced by olivine-spinel oxybarometry, high SO3 in apatite, and anhydrite saturation. The magma could therefore carry significantly more S than would have been possible at more reducing conditions, and the extent of ore metal sequestration by magmatic sulphide saturation was minimal. The SMI data show that the latites were Cu rich, with Cu concentrations in the silicate melt reaching up to 300-400 ppm at about 60 wt% SiO2. The Au and Ag concentrations are also high (1.5-4 and 50-200 ppb, respectively), but show less variation with SiO2. A sudden drop in Cu and S concentrations in the silicate melt at around 65 wt% SiO2 in the presence of high Cl, Mo, Ag, and Au shows that the onset of effective metal extraction by fluid exsolution occurred at a relatively late stage of magma evolution. Overall, our results show that fluid exsolution during simple magmatic differentiation of oxidized alkaline magmas is capable of producing giant porphyry Cu deposits.

Continuous microcellular foaming of polylactic acid/natural fiber composites

NASA Astrophysics Data System (ADS)

Diaz-Acosta, Carlos A.

Poly(lactic acid) (PLA), a biodegradable thermoplastic derived from renewable resources, stands out as a substitute to petroleum-based plastics. In spite of its excellent properties, commercial applications are limited because PLA is more expensive and more brittle than traditional petroleum-based resins. PLA can be blended with cellulosic fibers to reduce material cost. However, the lowered cost comes at the expense of flexibility and impact strength, which can be enhanced through the production of microcellular structures in the composite. Microcellular foaming uses inert gases (e.g., carbon dioxide) as physical blowing agents to make cellular structures with bubble sizes of less than 10 microm and cell-population densities (number of bubbles per unit volume) greater than 109 cells/cm³. These unique characteristics result in a significant increase in toughness and elongation at break (ductility) compared with unfoamed parts because the presence of small bubbles can blunt the crack-tips increasing the energy needed to propagate the crack. Microcellular foams have been produced through a two step batch process. First, large amounts of gas are dissolved in the solid plastic under high pressure (sorption process) to form a single-phase solution. Second, a thermodynamic instability (sudden drop in solubility) triggers cell nucleation and growth as the gas diffuses out of the plastic. Batch production of microcellular PLA has addressed some of the drawbacks of PLA. Unfortunately, the batch foaming process is not likely to be implemented in the industrial production of foams because it is not cost-effective. This study investigated the continuous microcellular foaming process of PLA and PLA/wood-fiber composites. The effects of the processing temperature and material compositions on the melt viscosity, pressure drop rate, and cell-population density were examined in order to understand the nucleation mechanisms in neat and filled PLA foams. The results indicated that the processing temperature had a strong effect of the rheology of the melt and cell morphology. Processing at a lower temperature significantly increased the cell nucleation rate of neat PLA (amorphous and semi-crystalline) because of the fact that a high melt viscosity induced a high pressure drop rate in the polymer/gas solution. The presence of nanoclay did not affect the homogeneous nucleation but increased the heterogeneous nucleation, allowing both nucleation mechanisms to occur during the foaming process. The effect of wood-flour (0-30 wt.%) and rheology modifier contents on the melt viscosity and cell morphology of microcellular foamed composites was investigated. The viscosity of the melt increased with wood-flour content and decreased with rheology modifier content, affecting the processing conditions (i.e., pressure drop and pressure drop rate) and foamability of the composites. Matching the viscosity of the composites with that of neat PLA resulted in the best cell morphologies. Physico-mechanical characterization of microcellular foamed PLA as a function of cell morphology was performed to establish process-morphology-property relationships. The processing variables, i.e., amount of gas injected, flow rate, and processing temperature affected the development of the cellular structure and mechanical properties of the foams.

Measurement of the spectral absorption of liquid water in melting snow with an imaging spectrometer

NASA Technical Reports Server (NTRS)

Green, Robert O.; Dozier, Jeff

1995-01-01

Melting of the snowpack is a critical parameter that drives aspects of the hydrology in regions of the earth where snow accumulates seasonally. New techniques for measurement of snow melt over regional scales offer the potential to improve monitoring and modeling of snow-driven hydrological processes. We present the results of measuring the spectral absorption of liquid water in a melting snowpack with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). AVIRIS data were acquired over Mammoth Mountain, in east central California on 21 May 1994 at 18:35 UTC. The air temperature at 2926 m on Mammoth Mountain at site A was measured at 15-minute intervals during the day preceding the AVIRIS data acquisition. At this elevation, the air temperature did not drop below freezing the night of May 20 and had risen to 6 degrees Celsius by the time of the overflight on May 21. These temperature conditions support the presence of melting snow at the surface as the AVIRIS data were acquired.

Coupled phase field, heat conduction, and elastodynamic simulations of kinetic superheating and nanoscale melting of aluminum nanolayer irradiated by picosecond laser.

PubMed

Hwang, Yong Seok; Levitas, Valery I

2015-12-21

An advanced continuum model for nanoscale melting and kinetic superheating of an aluminum nanolayer irradiated by a picosecond laser is formulated. Barrierless nucleation of surface premelting and melting occurs, followed by a propagation of two solid-melt interfaces toward each other and their collision. For a slow heating rate of Q = 0.015 K ps(-1) melting occurs at the equilibrium melting temperature under uniaxial strain conditions T = 898.1 K (i.e., below equilibrium melting temperature Teq = 933.67 K) and corresponding biaxial stresses, which relax during melting. For a high heating rate of Q = 0.99-84 K ps(-1), melting occurs significantly above Teq. Surprisingly, an increase in heating rate leads to temperature reduction at the 3 nm wide moving interfaces due to fast absorption of the heat of fusion. A significant, rapid temperature drop (100-500 K, even below melting temperature) at the very end of melting is revealed, which is caused by the collision of two finite-width interfaces and accelerated melting in about the 5 nm zone. For Q = 25-84 K ps(-1), standing elastic stress waves are observed in a solid with nodal points at the moving solid-melt interfaces, which, however, do not have a profound effect on melting time or temperatures. When surface melting is suppressed, barrierless bulk melting occurs in the entire sample, and elastodynamic effects are more important. Good correspondence with published, experimentally-determined melting time is found for a broad range of heating rates. Similar approaches can be applied to study various phase transformations in different materials and nanostructures under high heating rates.

Pseudotachylyte increases the post-slip strength of faults

USGS Publications Warehouse

Proctor, Brooks; Lockner, David A.

2016-01-01

Solidified frictional melts, or pseudotachylytes, are observed in exhumed faults from across the seismogenic zone. These unique fault rocks, and many experimental studies, suggest that frictional melting can be an important process during earthquakes. However, it remains unknown how melting affects the post-slip strength of the fault and why many exhumed faults do not contain pseudotachylyte. Analyses of triaxial stick-slip events on Westerly Granite (Rhode Island, USA) sawcuts at confining pressures from 50 to 400 MPa show evidence for frictional heating, including some events energetic enough to generate surface melt. Total and partial stress drops were observed with slip as high as 6.5 mm. We find that in dry samples following melt-producing stick slip, the shear failure strength increased as much as 50 MPa, while wet samples had <10 MPa strengthening. Microstructural analysis indicates that the strengthening is caused by welding of the slip surface during melt quenching, suggesting that natural pseudotachylytes may also strengthen faults after earthquakes. These results predict that natural pseudotachylyte will inhibit slip reactivation and possibly generate stress heterogeneities along faults. Wet samples do not exhibit melt welding, possibly because of thermal pressurization of water reducing frictional heating during slip.

Of drops and bubbles - The technology of space processing

NASA Technical Reports Server (NTRS)

Subramanian, R. Shankar

1984-01-01

It is possible to manipulate a large, molten mass of material, such as a glass, aboard an orbital platform using acoustic fields. Attention is presently given to the problem of bubble removal from such a melt; it is desirable to make small bubbles coalesce into larger ones through floating melt rotation, to create an artificial convective field in which the bubbles will move centripetally to the axis of rotation. Computer models of bubble migration have been developed in order to define the operational conditions required aboard such experiment platforms as the Space Shuttle Orbiter.

Initial Microstructure Evaluation of a U3Si2 + W Fuel Pin Fabricated Via Arc Melt Gravity Drop Casting

NASA Astrophysics Data System (ADS)

Hoggan, Rita E.; Harp, Jason M.

2018-02-01

Injection casting has historically been used to fabricate metallic nuclear fuel on a large scale. Casting of intermetallic fuel forms, such as U3Si2, may be an alternative pathway for fabrication of fuel pins to powder metallurgy. To investigate casting on a small scale, arc melt gravity drop casting was employed to cast a one-off pin of U3Si2 for evaluation as a fabrication method for U3Si2 as a light water reactor fuel. The pin was sectioned and examined via optical microscopy and scanning electron microscopy equipped with energy dispersive x-ray spectroscopy (EDS). Image analysis was used to estimate the volume fraction of phase impurities as well as porosity. The primary phase determined by EDS was U3Si2 with U-O and U-Si-W phase impurities. Unusually high levels of tungsten were observed because of accidental tungsten introduction during arc melting. No significant changes in microstructure were observed after annealing a section of the pin at 800°C for 72 h. The average density of the sectioned specimens was 12.4 g/cm3 measured via Archimedes principle immersion density and He gas displacement.

Analysis of Skylab fluid mechanics science demonstrations

NASA Technical Reports Server (NTRS)

Tegart, J. R.; Butz, J. R.

1975-01-01

The results of the data reduction and analysis of the Skylab fluid mechanics demonstrations are presented. All the fluid mechanics data available from the Skylab missions were identified and surveyed. The significant fluid mechanics phenomena were identified and reduced to measurable quantities wherever possible. Data correlations were performed using existing theories. Among the phenomena analyzed were: static low-g interface shapes, oscillation frequency and damping of a liquid drop, coalescence, rotating drop, liquid films and low-g ice melting. A survey of the possible applications of the results was made and future experiments are recommended.

Non-contact temperature measurement of a falling drop

NASA Technical Reports Server (NTRS)

Hofmeister, William; Bayuzick, R. J.; Robinson, M. B.

1989-01-01

The 105 meter drop tube at NASA-Marshall has been used in a number of experiments to determine the effects of containerless, microgravity processing on the undercooling and solidification behavior of metals and alloys. These experiments have been limited, however, because direct temperature measurement of the falling drops has not been available. Undercooling and nucleation temperatures are calculated from thermophysical properties based on droplet cooling models. In most cases these properties are not well known, particularly in the undercooled state. This results in a large amount of uncertainty in the determination of nucleation temperatures. If temperature measurement can be accomplished then the thermal history of the drops could be well documented. This would lead to a better understanding of the thermophysical and thermal radiative properties of undercooled melts. An effort to measure the temperature of a falling drop is under way. The technique uses two color pyrometry and high speed data acquisition. The approach is presented along with some preliminary data from drop tube experiments. The results from droplet cooling models is compared with noncontact temperature measurements.

Energy-efficient modification of reduction-melting for lead recovery from cathode ray tube funnel glass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okada, Takashi, E-mail: t-okada@u-fukui.ac.jp; Yonezawa, Susumu

2013-08-15

Highlights: • We recovered Pb from cathode ray tube funnel glass using reduction melting process. • We modified the melting process to achieve Pb recovery with low energy consumption. • Pb in the funnel glass is efficiently recovered at 1000 °C by adding Na{sub 2}CO{sub 3}. • Pb remaining in the glass after reduction melting is extracted with 1 M HCl. • 98% of Pb in the funnel glass was recovered by reduction melting and HCl leaching. - Abstract: Lead can be recovered from funnel glass of waste cathode ray tubes via reduction melting. While low-temperature melting is necessary formore » reduced energy consumption, previously proposed methods required high melting temperatures (1400 °C) for the reduction melting. In this study, the reduction melting of the funnel glass was performed at 900–1000 °C using a lab-scale reactor with varying concentrations of Na{sub 2}CO{sub 3} at different melting temperatures and melting times. The optimum Na{sub 2}CO{sub 3} dosage and melting temperature for efficient lead recovery was 0.5 g per 1 g of the funnel glass and 1000 °C respectively. By the reduction melting with the mentioned conditions, 92% of the lead in the funnel glass was recovered in 60 min. However, further lead recovery was difficult because the rate of the lead recovery decreased as with the recovery of increasing quantity of the lead from the glass. Thus, the lead remaining in the glass after the reduction melting was extracted with 1 M HCl, and the lead recovery improved to 98%.« less

Properties of Free-Machining Aluminum Alloys at Elevated Temperatures

NASA Astrophysics Data System (ADS)

Faltus, Jiří; Karlík, Miroslav; Haušild, Petr

In areas close to the cutting tool the workpieces being dry machined could be heated up to 350°C and they may be impact loaded. Therefore it is of interest to study mechanical properties of corresponding materials at elevated temperatures. Free-machining alloys of Al-Cu and Al-Mg-Si systems containing Pb, Bi and Sn additions (AA2011, AA2111B, AA6262, and AA6023) were subjected to Charpy U notch impact test at the temperatures ranging from 20 to 350°C. The tested alloys show a sharp drop in notch impact strength KU at different temperatures. This drop of KU is caused by liquid metal embrittlement due to the melting of low-melting point dispersed phases which is documented by differential scanning calorimetry. Fracture surfaces of the specimens were observed using a scanning electron microscope. At room temperature, the fractures of all studied alloys exhibited similar ductile dimple fracture micromorphology, at elevated temperatures, numerous secondary intergranular cracks were observed.

Albedo Drop on the Greenland Ice Sheet: Relative Impacts of Wet and Dry Snow Processes

NASA Astrophysics Data System (ADS)

Chen, J.; Polashenski, C.

2014-12-01

The energy balance of the Greenland Ice Sheet (GIS) is strongly impacted by changes in snow albedo. MODIS (Moderate Resolution Imaging Spectroradiometer) observations indicate that the GIS albedo has dropped since the early part of this century. We analyze data from the MODIS products MOD10A1 for broadband snow albedo and MOD09A1 for surface spectral reflectance since 2001 to better explain the physical mechanisms driving these changes. The MODIS products are filtered, and the data is masked using microwave-derived surface melt maps to isolate albedo changes due to dry snow processes from those driven by melt impacts. Results show that the majority of recent changes in the GIS albedo - even at high elevations - are driven by snow wetting rather than dry snow processes such as grain metamorphosis and aerosol impurity deposition. The spectral signature of the smaller changes occurring within dry snow areas suggests that grain metamorphosis dominates the albedo decline in these regions.

Pharmacological activities of an eye drop containing Matricaria chamomilla and Euphrasia officinalis extracts in UVB-induced oxidative stress and inflammation of human corneal cells.

PubMed

Bigagli, Elisabetta; Cinci, Lorenzo; D'Ambrosio, Mario; Luceri, Cristina

2017-08-01

Ultraviolet B (UVB) exposure is a risk factor for corneal damage resulting in oxidative stress, inflammation and cell death. The aim of this study was to investigate the potential protective effects of a commercial eye drop (Dacriovis™) containing Matricaria chamomilla and Euphrasia officinalis extracts on human corneal epithelial cells (HCEC-12) against UVB radiation-induced oxidative stress and inflammation as well as the underlying mechanisms. The antioxidant potential of the eye drops was evaluated by measuring the ferric reducing antioxidant power and the total phenolic content by Folin-Ciocalteu reagent. HCEC-12 cells were exposed to UVB radiation and treated with the eye drops at various concentrations. Cell viability, wound healing assay, reactive oxygen species (ROS) levels, protein and lipid oxidative damage and COX-2, IL-1β, iNOS, SOD-2, HO-1 and GSS gene expression, were assessed. Eye drops were able to protect corneal epithelial cells from UVB-induced cell death and ameliorated the wound healing; the eye drops exhibited a strong antioxidant activity, decreasing ROS levels and protein and lipid oxidative damage. Eye drops also exerted anti-inflammatory activities by decreasing COX-2, IL-1β, iNOS expression, counteracted UVB-induced GSS and SOD-2 expression and restored HO-1 expression to control levels. These findings suggest that an eye drop containing Matricaria chamomilla and Euphrasia officinalis extracts exerts positive effects against UVB induced oxidative stress and inflammation and may be useful in protecting corneal epithelial cells from UVB exposure. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantifying precambrian crustal extraction: The root is the answer

USGS Publications Warehouse

Abbott, D.; Sparks, D.; Herzberg, C.; Mooney, W.; Nikishin, A.; Zhang, Y.-S.

2000-01-01

We use two different methods to estimate the total amount of continental crust that was extracted by the end of the Archean and the Proterozoic. The first method uses the sum of the seismic thickness of the crust, the eroded thickness of the crust, and the trapped melt within the lithospheric root to estimate the total crustal volume. This summation method yields an average equivalent thickness of Archean crust of 49 ?? 6 km and an average equivalent thickness of Proterozoic crust of 48 ?? 9 km. Between 7 and 9% of this crust never reached the surface, but remained within the continental root as congealed, iron-rich komatiitic melt. The second method uses experimental models of melting, mantle xenolith compositions, and corrected lithospheric thickness to estimate the amount of crust extracted through time. This melt column method reveals that the average equivalent thickness of Archean crust was 65 ?? 6 km. and the average equivalent thickness of Early Proterozoic crust was 60 ?? 7 km. It is likely that some of this crust remained trapped within the lithospheric root. The discrepancy between the two estimates is attributed to uncertainties in estimates of the amount of trapped, congealed melt, overall crustal erosion, and crustal recycling. Overall, we find that between 29 and 45% of continental crust was extracted by the end of the Archean, most likely by 2.7 Ga. Between 51 and 79% of continental crust was extracted by the end of the Early Proterozoic, most likely by 1.8-2.0 Ga. Our results are most consistent with geochemical models that call upon moderate amounts of recycling of early extracted continental crust coupled with continuing crustal growth (e.g. McLennan, S.M., Taylor, S.R., 1982. Geochemical constraints on the growth of the continental crust. Journal of Geology, 90, 347-361; Veizer, J., Jansen, S.L., 1985. Basement and sedimentary recycling - 2: time dimension to global tectonics. Journal of Geology 93(6), 625-643). Trapped, congealed, iron-rich melt within the lithospheric root may represent some of the iron that is 'missing' from the lower crust. The lower crust within Archean cratons may also have an unexpectedly low iron content because it was extracted from more primitive, undepleted mantle. (C) 2000 Elsevier Science B.V. All rights reserved.

Making rhyolite in a basalt crucible

NASA Astrophysics Data System (ADS)

Eichelberger, John

2016-04-01

Iceland has long attracted the attention of those concerned with the origin of rhyolitic magmas and indeed of granitic continental crust, because it presents no alternative for such magmas other than deriving them from a basaltic source. Hydrothermally altered basalt has been identified as the progenitor. The fact that rhyolite erupts as pure liquid requires a process of melt-crustal separation that is highly efficient despite the high viscosity of rhyolite melt. Volcanoes in Iceland are foci of basaltic magma injection along the divergent plate boundary. Repeated injection produces remelting, digestion, and sometimes expulsion or lateral withdrawal of material resulting in a caldera, a "crucible" holding down-dropped and interlayered lava flows, tephras, and injected sills. Once melting of this charge begins, a great deal of heat is absorbed in the phase change. Just 1% change in crystallinity per degree gives a melt-present body an effective heat capacity >5 times the subsolidus case. Temperature is thus buffered at the solidus and melt composition at rhyolite. Basalt inputs are episodic ("fires") so likely the resulting generation of rhyolite by melting is too. If frequent enough to offset cooling between events, rhyolite melt extractions will accumulate as a rhyolite magma reservoir rather than as discrete crystallized sills. Evidently, such magma bodies can survive multiple firings without themselves erupting, as the 1875 eruption of Askja Caldera of 0.3 km3 of rhyolite equilibrated at 2-km depth without previous leakage over a ten-millennium period and the surprise discovery of rhyolite magma at 2-km depth in Krafla suggest. Water is required for melting; otherwise melting cannot begin at a temperature lower than that of the heat source. Because the solubility of water in melt is pressure-dependent and almost zero at surface pressure, there must be a minimum depth at which basalt-induced melting can occur and a rhyolite reservoir sustained. In practice, the storage limit is likely near 2-km depth at which IDDP-1 and other Krafla boreholes encountered rhyolite melt. Rearrangement of components within the crucible during brewing produces little in terms of a gravity or deformation signals, hence the surprise in finding newly intruded magma. Below 2 km much of the charge in the crucible is near the basalt solidus, so that pockets, sills, and chambers of near-liquidus rhyolite magma will all be close to thermal and chemical equilibrium. Heat is advected upwards from the mantle first by basalt to the crucible, then by rhyolite magma within the crucible, then by hydrothermal fluid to the surface. A major portion of the thermal energy is stored as latent heat of crystallization of rhyolite magma. Such a view challenges some basic tenets of volcano hazard assessment and geothermal energy. The Krafla Magma Drilling Project of the International Continental Scientific Drilling Program will provide a critical test in 2017 by coring from subsolidus granite to liquidus rhyolite, wherein the transitions of heat advection by hydrothermal fluid, to heat conduction, to heat advection by rhyolite magma must occur.

Headspace single drop microextraction coupled with microwave extraction of essential oil from plant materials.

PubMed

Zhai, Yujuan; Sun, Shuo; Wang, Ziming; Zhang, Yupu; Liu, He; Sun, Ye; Zhang, Hanqi; Yu, Aimin

2011-05-01

Headspace single drop microextraction (HS-SDME) coupled with microwave extraction (ME) was developed and applied to the extraction of the essential oil from dried Syzygium aromaticum (L.) Merr. et Perry and Cuminum cyminum L. The operational parameters, such as microdrop volume, microwave absorption medium (MAM), extraction time, and microwave power were optimized. Ten microliters of decane was used as the microextraction solvent. Ionic liquid and carbonyl iron powder were used as MAM. The extraction time was less than 7 min at the microwave power of 440 W. The proposed method was compared with hydrodistillation (HD). There were no obvious differences in the constituents of essential oils obtained by the two methods.

A Re-Os Study of Depleted Trench Peridotites from Northern Mariana

NASA Astrophysics Data System (ADS)

Ghosh, T.; Snow, J. E.; Heri, A. R.; Brandon, A. D.; Ishizuka, O.

2017-12-01

Trench peridotites provide information about the influence of subduction initiation on the extent of mantle wedge melting. They preserve melting records throughout subduction history, and as a result, likely experience multiple melt extraction events leading to successive depletion of melt/fluid mobile major and trace elements. To track melting histories of trench peridotites, Re-Os and PGEs can be used as reliable tracers to constrain early melt extraction or re-fertilization events. The Izu-Bonin-Mariana arc, being the largest intra-oceanic subduction system, provides an excellent area to study the formation of supra-subduction zone mantle and crust. Residual peridotite (harzburgite and dunite) samples were collected by dredging from the landward slope of the northern Mariana Trench. The samples are serpentinized to various extents (typical of abyssal peridotites), leaving behind relict grains of spinel, enstatite and olivine embedded within a serpentine matrix along with occasional interstitial diopside. Major element analyses of primary minerals reveal a wide range of variations in Cr# of spinels from 0.31-0.85 indicating 16-20% of melt fraction with dunites apparently experiencing the highest amount of partial melting. For Re-Os and PGE geochemistry, samples with high amounts of spinel (>4 vol %) and variable Cr# were chosen. Initial results show that bulk rock 187Os/188Os ratios range from 0.1113 to 0.1272. All of the samples are sub-chondritic, but in some cases, they are more radiogenic than average abyssal peridotites. Os abundances vary from 1-9 ppb. Sub-chondritic values can be attributed to the samples having evolved from a Re-depleted mantle source indicating a previous melt-extraction event. The cpx-harzburgites, having lower Cr# ( 0.4) are more radiogenic than ultra depleted dunites (Cr# 0.8), which might indicate preferential removal of Os during an apparent higher degree of partial melting experienced by dunites. The higher 187Os/188Os ratios of cpx-harzburgites possibly imply a late stage melt-rock interaction event, which had refertilized the depleted samples in radiogenic Os. Since there are only trace amounts of sediments in the accretionary prism of N. Mariana, Os ratios of these trench peridotites are not influenced by Os from sediments.

Viscosity Measurement for Tellurium Melt

NASA Technical Reports Server (NTRS)

Lin, Bochuan; Li, Chao; Ban, Heng; Scripa, Rosalia N.; Su, Ching-Hua; Lehoczky, Sandor L.

2006-01-01

The viscosity of high temperature Te melt was measured using a new technique in which a rotating magnetic field was applied to the melt sealed in a suspended ampoule, and the torque exerted by rotating melt flow on the ampoule wall was measured. Governing equations for the coupled melt flow and ampoule torsional oscillation were solved, and the viscosity was extracted from the experimental data by numerical fitting. The computational result showed good agreement with experimental data. The melt velocity transient initiated by the rotating magnetic field reached a stable condition quickly, allowing the viscosity and electrical conductivity of the melt to be determined in a short period.

Production of Magnesium and Aluminum-Magnesium Alloys from Recycled Secondary Aluminum Scrap Melts

NASA Astrophysics Data System (ADS)

Gesing, Adam J.; Das, Subodh K.; Loutfy, Raouf O.

2016-02-01

An experimental proof of concept was demonstrated for a patent-pending and trademark-pending RE12™ process for extracting a desired amount of Mg from recycled scrap secondary Al melts. Mg was extracted by electrorefining, producing a Mg product suitable as a Mg alloying hardener additive to primary-grade Al alloys. This efficient electrorefining process operates at high current efficiency, high Mg recovery and low energy consumption. The Mg electrorefining product can meet all the impurity specifications with subsequent melt treatment for removing alkali contaminants. All technical results obtained in the RE12™ project indicate that the electrorefining process for extraction of Mg from Al melt is technically feasible. A techno-economic analysis indicates high potential profitability for applications in Al foundry alloys as well as beverage—can and automotive—sheet alloys. The combination of technical feasibility and potential market profitability completes a successful proof of concept. This economical, environmentally-friendly and chlorine-free RE12™ process could be disruptive and transformational for the Mg production industry by enabling the recycling of 30,000 tonnes of primary-quality Mg annually.

Process modelling for space station experiments

NASA Technical Reports Server (NTRS)

Rosenberger, Franz; Alexander, J. Iwan D.

1988-01-01

The work performed during the first year 1 Oct. 1987 to 30 Sept. 1988 involved analyses of crystal growth from the melt and from solution. The particular melt growth technique under investigation is directional solidification by the Bridgman-Stockbarger method. Two types of solution growth systems are also being studied. One involves growth from solution in a closed container, the other concerns growth of protein crystals by the hanging drop method. Following discussions with Dr. R. J. Naumann of the Low Gravity Science Division at MSFC it was decided to tackle the analysis of crystal growth from the melt earlier than originally proposed. Rapid progress was made in this area. Work is on schedule and full calculations were underway for some time. Progress was also made in the formulation of the two solution growth models.

Dynamic Nucleation of Supercooled Melts and Measurement of the Surface Tension and Viscosity

NASA Technical Reports Server (NTRS)

Trinh, E. H.; Ohsaka, K.

1999-01-01

We investigate the phenomenon of acoustic pressure-induced nucleation by using a novel approach involving the large amplitude resonant radial oscillations and collapse of a single bubble intentionally injected into a supercooled liquid. Using a combination of previously developed and proven techniques, the bubble is suspended in a fluid host by an ultrasonic field which supplies both the levitation capability as well as the forcing of the radial oscillations. We observe the effects of an increase in pressure (due to bubble collapse) in a region no larger than 100 microns within the supercooled melt to rigorously probe the hypothesis of pressure-induced nucleation of the solid phase. The use of single bubbles operating in narrow temporal and spatial scales will allow the direct and unambiguous correlation between the origin and location of the generation of the disturbance and the location and timing of the nucleation event. In a companion research effort, we are developing novel techniques for the non-contact measurements of the surface tension and viscosity of highly viscous supercooled liquids. Currently used non-invasive methods of surface tension measurement for the case of undercooled liquids generally rely of the quantitative determination of the resonance frequencies of drop shape oscillations, of the dynamics of surface capillary waves, or of the velocity of streaming flows. These methods become quickly ineffective when the liquid viscosity rises to a significant value. An alternate and accurate method which would be applicable to liquids of significant viscosity is therefore needed. We plan to develop such a capability by measuring the equilibrium shape of levitated undercooled melt droplets as they undergo solid-body rotation. The experimental measurement of the characteristic point of transition (bifurcation point) between axisymmetric and two-lobed shapes will be used to calculate the surface tension of the liquid. Such an approach has already been validated through the experimental verification of numerical modeling results. The experimental approach involves levitation, melting, and solidification of undercooled droplets using a hybrid ultrasonic-electrostatic technique in both a gaseous as well as a vacuum environment. A shape relaxation method will be investigated in order to derive a reliable method to measure the viscosity of undercooled melts. The analysis of the monotonic relaxation to equilibrium shape of a drastically deformed and super-critically damped free drop has been used to derive interfacial tension of immiscible liquid combinations where one of the component has high viscosity. A standard approach uses the initial elongation of a droplet through shear flows, but an equivalent method could involve the initial deformation of a drop levitated in a gas by ultrasonic radiation pressure, electric stresses, or even solid body rotation. The dynamic behavior of the free drop relaxing back to equilibrium shape will be modeled, and its characteristic time dependence should provide a quantitative means to evaluate the liquid viscosity.

Very Large Rain Drops from 2D Video Disdrometers and Concomitant Polarimetric Radar Observations

NASA Technical Reports Server (NTRS)

Thurai, Merhala; Gatlin, Patrick; Bringi, V. N.; Carey, Lawrence

2014-01-01

Drop size distribution (DSD) measurements using ground-based disdrometers (point measurements) have often been used to derive equations to relate radar observations to the integral rainfall parameters (Atlas et al. 1999, Bringi et al., 2003, Kozu et al., 2006, Tokay and Short, 1996, Ajayi and Owolabi, 1987, Battan, 1973). Disdrometers such as JWD, MRR and several others have a major limitation in measuring drops with equi-volume diameters (D(sub eq)) larger than 5 mm because they often rely on the velocity-diameter relationship which plateaus beyond this diameter range (Atlas et al., 1973, Gunn & Kinzer, 1949). Other disdrometers such as Parsivel also lack accuracy beyond this diameter range. The 2D video disdrometer (2DVD: Schönhuber et al., 2008) on the other hand gives drop-shape contours and velocities for each individual drop/hydrometeor falling through its sensor area; this provides a unique opportunity to study the role of very-large drops on radar measurements in particular those with polarimetric radar capability where DSDs with a significant component of very large drops may require special consideration given that the differential reflectivity and other polarimetric radar parameters including attenuation-correction methods will be sensitive to the concentrations of these large drops. A recent study on the occurrence of large drops by Gatlin et al. (2014) has compiled a large and diverse set of measurements made with the 2D video disdrometers from many locations around the globe. Some of the largest drops found in this study were 9 mm D(sub eq) and larger, and in this paper, we report on three such events, with maximum D(sub eq's) of 9.0, 9.1 and 9.7 mm, which occurred in Colorado, Northern Alabama, and Oklahoma, respectively. Detailed examination of the 2DVD data - in terms of shapes and fall velocities - has confirmed that these are fully-melted hydrometeors, although for the last case in Oklahoma, a bigger and non-fully-melted hydrometeor was also observed. All three events were also captured by polarimetric radars, namely the S-band CHILL radar operated by Colorado State University (Brunkow et al., 2000), the C-band ARMOR radar (Petersen et al., 2007) operated by University of Alabama in Huntsville, and NEXRADKVNX, operated by the US National Weather Service, respectively. For the last event, several other radar observations were also made, including two X-band radars operated by the US Dept. of Energy. Analyses of 2DVD data in conjunction with the corresponding radar observations are presented, along with some discussion on sampling issues related to the measurements of such large rain drops. The latter is addressed using maximum diameter D(sub max) measurements from 1-minute DSDs using two collocated 2DVDs for 37 events in Huntsville.

Measurement of the Spectral Absorption of Liquid Water in Melting Snow With an Imaging Spectrometer

NASA Technical Reports Server (NTRS)

Green, Robert O.; Dozier, Jeff

1995-01-01

Melting of the snowpack is a critical parameter that drives aspects of the hydrology in regions of the Earth where snow accumulates seasonally. New techniques for measurement of snow melt over regional scales offer the potential to improve monitoring and modeling of snow-driven hydrological processes. In this paper we present the results of measuring the spectral absorption of liquid water in a melting snowpack with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). AVIRIS data were acquired over Mammoth Mountain, in east central California on 21 May 1994 at 18:35 UTC. The air temperature at 2926 m on Mammoth Mountain at site A was measured at 15-minute intervals during the day preceding the AVIRIS data acquisition. At this elevation. the air temperature did not drop below freezing the night of the May 20 and had risen to 6 degrees Celsius by the time of the overflight on May 21. These temperature conditions support the presence of melting snow at the surface as the AVIRIS data were acquired.

The use of containerless processing in researching reactive materials

NASA Technical Reports Server (NTRS)

Weber, J. K. R.; Krishnan, Shankar; Nordine, Paul C.

1991-01-01

It has recently become possible to perform containerless, high-temperature liquid-phase processing of many nonvolatile materials without resort to orbital microgravity, thereby facilitating the conduct of materials research in conjunction with noncontact diagnostic instruments. The melt-levitation techniques are electromagnetic, aerodynamic, acoustic, aeroacoustic, and electrostatic; nonorbital microgravity conditions are obtainable aboard NASA's KC-135 aircraft on parabolic flight paths, as well as in drop tubes and towers. Applications encompass the purification of metals and the creation of nonequilibrium and metastable structures. Process control and property measurements include optical pyrometry and emissivity, laser polarimetry, and drop calorimetry.

Morphology and Magnetic Properties of Ferriferous Two-Phase Sodium Borosilicate Glasses

PubMed Central

Naberezhnov, Alexander; Porechnaya, Nadezda; Nizhankovskii, Viktor; Filimonov, Alexey; Nacke, Bernard

2014-01-01

This contribution is devoted to the study of morphology and magnetic properties of sodium borosilicate glasses with different concentrations (15, 20, and 25 wt.%) of α-Fe2O3 in an initial furnace charge. These glasses were prepared by a melt-quenching method. For all glasses a coexistence of drop-like and two-phase interpenetrative structures is observed. The most part of a drop structure is formed by self-assembling iron oxides particles. All types of glasses demonstrate the magnetic properties and can be used for preparation of porous magnetic matrices with nanometer through dendrite channel structure. PMID:25162045

Ultrasonication followed by single-drop microextraction combined with GC/MS for rapid determination of organochlorine pesticides from fish.

PubMed

Shrivas, Kamlesh; Wu, Hui-Fen

2008-02-01

A novel, rapid and simple sample pretreatment technique termed ultrasonication followed by single-drop micro-extraction (U-SDME) has been developed and combined with GC/MS for the determination of organochlorine pesticides (OCPs) in fish. In the present work, the lengthy procedures generally used in the conventional methods like, Soxhlet extraction, supercritical fluid extraction, pressurized liquid extraction and microwave assisted solvent extraction for extraction of OCPs from fish tissues are minimized by the use of two simple extraction procedures. Firstly, OCPs from fish were extracted in organic solvent with ultrasonication and then subsequently preconcentrated by single-drop micro-extraction (SDME). Extraction parameters of ultrasonication and SDME were optimized in spiked sample solution in order to obtain efficient extraction of OCPs from fish tissues. The calibration curves for OCPs were found to be linear between 10-1000 ng/g with correlation of estimations in the range 0.990-0.994. The recoveries obtained in blank fish tissues were ranged from 82.1 to 95.3%. The LOD and RSD for determination of OCPs in fish were 0.5 ng/g and 9.4-10.0%, respectively. The proposed method was applied for the determination of bioconcentration factor in fish after exposure to different concentrations of OCPs in cultured water. The present method avoids the co-extraction of lipids, long extraction steps (>12 h) and large amount of organic solvent for the separation of OCPs. The main advantages of the present method are rapid, selective, sensitive and low cost for the determination of OCPs in fish.

Bubble and Drop Nonlinear Dynamics (BDND)

NASA Technical Reports Server (NTRS)

Trinh, E. H.; Leal, L. Gary; Thomas, D. A.; Crouch, R. K.

1998-01-01

Free drops and bubbles are weakly nonlinear mechanical systems that are relatively simple to characterize experimentally in 1-G as well as in microgravity. The understanding of the details of their motion contributes to the fundamental study of nonlinear phenomena and to the measurement of the thermophysical properties of freely levitated melts. The goal of this Glovebox-based experimental investigation is the low-gravity assessment of the capabilities of a modular apparatus based on ultrasonic resonators and on the pseudo- extinction optical method. The required experimental task is the accurate measurements of the large-amplitude dynamics of free drops and bubbles in the absence of large biasing influences such as gravity and levitation fields. A single-axis levitator used for the positioning of drops in air, and an ultrasonic water-filled resonator for the trapping of air bubbles have been evaluated in low-gravity and in 1-G. The basic feasibility of drop positioning and shape oscillations measurements has been verified by using a laptop-interfaced automated data acquisition and the optical extinction technique. The major purpose of the investigation was to identify the salient technical issues associated with the development of a full-scale Microgravity experiment on single drop and bubble dynamics.

Containerless processing of undercooled melts

NASA Technical Reports Server (NTRS)

Shong, D. S.; Graves, J. A.; Ujiie, Y.; Perepezko, J. H.

1987-01-01

Containerless drop tube processing allows for significant levels of liquid undercooling through control of parameters such as sample size, surface coating and cooling rate. A laboratory scale (3 m) drop tube has been developed which allows the undercooling and solidification behavior of powder samples to be evaluated under low gravity free-fall conditions. The level of undercooling obtained in an InSb-Sb eutectic alloy has been evaluated by comparing the eutectic spacing in drop tube samples with a spacing/undercooling relationship established using thermal analysis techniques. Undercoolings of 0.17 and 0.23 T(e) were produced by processing under vacuum and He gas conditions respectively. Alternatively, the formation of an amorphous phase in a Ni-Nb eutectic alloy indicates that undercooling levels of approximately 500 C were obtained by drop tube processing. The influence of droplet size and gas environment on undercooling behavior in the Ni-Nb eutectic was evaluated through their effect on the amorphous/crystalline phase ratio. To supplement the structural analysis, heat flow modeling has been developed to describe the undercooling history during drop tube processing, and the model has been tested experimentally.

Predicting relative sea level changes at the aftermath of Marinoan (635 Ma) Snowball meltdown

NASA Astrophysics Data System (ADS)

Irie, Y.; Nakada, M.; Okuno, J.; Bao, H.

2016-12-01

Earth system recovery from a Snowball state constitutes one of the best tests of the resilience of life on planet Earth. A distinct and probably brief relative sea level (RSL) drop has been identified in the cap dolostones deposited in a general transgression sequence at the aftermath of Marinoan Snowball meltdown in South China and other late Neoproterozoic blocks. However, the magnitude and duration or the very existence of this RSL drop event can vary at different geographical sites because of spatial and temporal variations in sea level due to glacial isostatic adjustment (GIA) even for tectonically stable areas. An accurate prediction of this drop can in turn help us infer independently the rate of dynamic recovery of the Earth system from a Snowball state, e.g. the timing and duration of the Marinoan 17O depletion (MOSD) event that was also closely linked to the rise and drawdown of atmospheric O2 and CO2, respectively. Here we model the RSL changes by considering all GIA-related relaxation processes. We evaluated the RSL to the sea level at 10 Myr after the complete glacial meltdown and tested slightly different paleogeographic configurations. Our modeling results show that the RSL drop occurs in the syn-deglacial phase (melting phase) for the inland regions and in the post-deglacial phase (time after the complete melting) for continental margins. The RSL drop in the post-deglacial phase is mainly determined by the relaxation processes with a timescale of longer than 20 kyr. The predicted RSL change in South China for lower mantle viscosity of 1022-1023 Pa s and a syn-deglacial time of <100 kyr is consistent with the observationally inferred RSL change regardless of uncertainties on the length of the continental shelf or the paleogeography of South China. A comparison between our model predicted and sedimentary-record inferred RSL change in South China put an independent constraint on the duration of the MOSD event at 70 kyr or shorter.

Source Mechanism of Vulcanian Degassing at Popocatépetl Volcano, Mexico, Determined From Moment-Tensor Inversion of Very-long-period Seismic Waveforms

NASA Astrophysics Data System (ADS)

Chouet, B.; Dawson, P.; Arciniega, A.

2004-12-01

The source mechanism of very-long-period (VLP) signals accompanying degassing exhalations at Popocatépetl is analyzed in the 15-70~s band by minimizing the residual error between data and synthetics calculated for a point source embedded in a homogeneous medium. The waveforms of two events (04/23/00, 05/23/00) representative of mild Vulcanian eruptions are well reproduced by our inversion, which takes into account volcano topography. The source centroid is positioned 1500~m below the western perimeter of the summit crater, and the modeled source is composed of a shallow-dipping crack (sill with easterly dip of 10° ) intersecting a steeply-dipping crack (northeast striking dike with northwest dip of 83° ), whose surface trace bisects the vent. Both cracks undergo a similar sequence of inflation, deflation, and reinflation --- reflecting a cycle of pressurization, depressurization, and repressurization within a time interval of 3-5~min. The largest moment release occurs in the sill, showing a maximum volume change of 500-1000\\:m3, pressure drop of 3-5~MPa, and amplitude of recovered pressure equal to 1.2 times the amplitude of the pressure drop. In contrast, the maximum volume change in the dike is 200-300\\:m3, with a corresponding pressure drop of 1-2~MPa and pressure recovery equal to the pressure drop. Accompanying these volumetric sources is a single force with magnitude of 5 × 108~N, consistent with melt advection in response to the pressure transients. The source-time history of the three components of this force confirms that significant mass movement starts in the sill and triggers a mass movement response in the dike within ˜ 5~s. Such source behavior is consistent with the opening of an escape pathway for accumulated gases from slow pressurization of the sill driven by magma crystallization. The opening of a pathway for pent-up gases in the sill and rapid evacuation of this separated gas phase induces the pressure drop. Pressure recovery in the magma filling the sill is driven by diffusion of gases from the resulting supersaturated melt into bubbles. Assuming a penny-shaped crack at ambient pressure of 40~MPa, the observed pressure and volume variations can be modeled with the following attributes: crack radius, (100~m), crack aperture, (5~m), bubble number density, (1010 - 1012\\:m-3), initial bubble radius, (10-6\\:m), final bubble radius, ( ˜ 10-5\\:m), and net decrease of gas concentration in the melt, (0.01~wt%).

Source mechanism of Vulcanian degassing at Popocatépetl Volcano, Mexico, determined from waveform inversions of very long period signals

NASA Astrophysics Data System (ADS)

Chouet, Bernard; Dawson, Phillip; Arciniega-Ceballos, Alejandra

2005-07-01

The source mechanism of very long period (VLP) signals accompanying volcanic degassing bursts at Popocatépetl is analyzed in the 15-70 s band by minimizing the residual error between data and synthetics calculated for a point source embedded in a homogeneous medium. The waveforms of two eruptions (23 April and 23 May 2000) representative of mild Vulcanian activity are well reproduced by our inversion, which takes into account volcano topography. The source centroid is positioned 1500 m below the western perimeter of the summit crater, and the modeled source is composed of a shallow dipping crack (sill with easterly dip of 10°) intersecting a steeply dipping crack (northeast striking dike dipping 83° northwest), whose surface extension bisects the vent. Both cracks undergo a similar sequence of inflation, deflation, and reinflation, reflecting a cycle of pressurization, depressurization, and repressurization within a time interval of 3-5 min. The largest moment release occurs in the sill, showing a maximum volume change of 500-1000 m3, pressure drop of 3-5 MPa, and amplitude of recovered pressure equal to 1.2 times the amplitude of the pressure drop. In contrast, the maximum volume change in the dike is less (200-300 m3), with a corresponding pressure drop of 1-2 MPa and pressure recovery equal to the pressure drop. Accompanying these volumetric sources are single-force components with magnitudes of 108 N, consistent with melt advection in response to pressure transients. The source time histories of the volumetric components of the source indicate that significant mass movement starts within the sill and triggers a mass movement response in the dike within a few seconds. Such source behavior is consistent with the opening of a pathway for escape of pent-up gases from slow pressurization of the sill driven by magma crystallization. The opening of this pathway and associated rapid evacuation of volcanic gases induces the pressure drop. Pressure recovery in the magma filling the sill is driven by diffusion of gases from the resulting supersaturated melt into bubbles. Assuming a penny-shaped crack at ambient pressure of 40 MPa, the observed pressure and volume variations can be modeled with the following attributes: crack radius (100 m), crack aperture (5 m), bubble number density (1010-1012 m-3), initial bubble radius (10-6 m), final bubble radius (˜10-5 m), and net decrease of gas concentration in the melt (0.01 wt %).

Source mechanism of Vulcanian degassing at Popocatépetl Volcano, Mexico, determined from waveform inversions of very long period signals

USGS Publications Warehouse

Chouet, Bernard A.; Dawson, Phillip B.; Arciniega-Ceballos, Alejandra

2005-01-01

The source mechanism of very long period (VLP) signals accompanying volcanic degassing bursts at Popocatépetl is analyzed in the 15–70 s band by minimizing the residual error between data and synthetics calculated for a point source embedded in a homogeneous medium. The waveforms of two eruptions (23 April and 23 May 2000) representative of mild Vulcanian activity are well reproduced by our inversion, which takes into account volcano topography. The source centroid is positioned 1500 m below the western perimeter of the summit crater, and the modeled source is composed of a shallow dipping crack (sill with easterly dip of 10°) intersecting a steeply dipping crack (northeast striking dike dipping 83° northwest), whose surface extension bisects the vent. Both cracks undergo a similar sequence of inflation, deflation, and reinflation, reflecting a cycle of pressurization, depressurization, and repressurization within a time interval of 3–5 min. The largest moment release occurs in the sill, showing a maximum volume change of 500–1000 m3, pressure drop of 3–5 MPa, and amplitude of recovered pressure equal to 1.2 times the amplitude of the pressure drop. In contrast, the maximum volume change in the dike is less (200–300 m3), with a corresponding pressure drop of 1–2 MPa and pressure recovery equal to the pressure drop. Accompanying these volumetric sources are single-force components with magnitudes of 108 N, consistent with melt advection in response to pressure transients. The source time histories of the volumetric components of the source indicate that significant mass movement starts within the sill and triggers a mass movement response in the dike within a few seconds. Such source behavior is consistent with the opening of a pathway for escape of pent-up gases from slow pressurization of the sill driven by magma crystallization. The opening of this pathway and associated rapid evacuation of volcanic gases induces the pressure drop. Pressure recovery in the magma filling the sill is driven by diffusion of gases from the resulting supersaturated melt into bubbles. Assuming a penny-shaped crack at ambient pressure of 40 MPa, the observed pressure and volume variations can be modeled with the following attributes: crack radius (100 m), crack aperture (5 m), bubble number density (1010–1012 m−3), initial bubble radius (10−6 m), final bubble radius (∼10−5 m), and net decrease of gas concentration in the melt (0.01 wt %).

Impact of the Formulation Pathway on the Colloidal State and Crystallinity of Poly-ε-caprolactone Particles Prepared by Solvent Displacement.

PubMed

Pucci, Carlotta; Cousin, Fabrice; Dole, François; Chapel, Jean-Paul; Schatz, Christophe

2018-02-20

The formulation pathway and/or the mixing method are known to be relevant in many out-of-equilibrium processes. In this work, we studied the effect of the mixing conditions on the physicochemical properties of poly-ε-caprolactone (PCL) particles prepared by solvent displacement. More specifically, water was added in one shot (fast addition) or drop by drop to PCL solution in tetrahydrofuran (THF) to study the impact of the mixing process on particle properties including size, stability, and crystallinity. Two distinct composition maps representing the Ouzo domain characteristic of the presence of metastable nanoparticles have been established for each mixing method. Polymer nanoparticles are formed in the Ouzo domain according to a nucleation and growth (or aggregation) mechanism. The fast addition promotes a larger nucleation rate, thus favoring the formation of small and uniform particles. For the drop-by-drop addition, for which the polymer solubility gradually decreases, the composition trajectories systematically cross an intermediate unstable region between the solubility limit of the polymer and the Ouzo domain. This leads to heterogeneous nucleation as shown by the formation of larger and less stable particles. Particles formed in the Ouzo domain have semi-crystalline properties. The PCL melting point is decreased with the THF fraction trapped in particles in accordance with Flory's theory for melt crystallization. On the other hand, the degree of crystallinity is constant, around 20% regardless of the THF fraction. No difference between fast and slow addition could be detected on the semi-crystalline properties of the particles which emphasize that thermodynamic rather than kinetic factors drive the polymer crystallization in particles. The recovery of bulk PCL crystallinity after the removal of THF from particles tends to confirm this hypothesis.

Object-Based Arctic Sea Ice Feature Extraction through High Spatial Resolution Aerial photos

NASA Astrophysics Data System (ADS)

Miao, X.; Xie, H.

2015-12-01

High resolution aerial photographs used to detect and classify sea ice features can provide accurate physical parameters to refine, validate, and improve climate models. However, manually delineating sea ice features, such as melt ponds, submerged ice, water, ice/snow, and pressure ridges, is time-consuming and labor-intensive. An object-based classification algorithm is developed to automatically extract sea ice features efficiently from aerial photographs taken during the Chinese National Arctic Research Expedition in summer 2010 (CHINARE 2010) in the MIZ near the Alaska coast. The algorithm includes four steps: (1) the image segmentation groups the neighboring pixels into objects based on the similarity of spectral and textural information; (2) the random forest classifier distinguishes four general classes: water, general submerged ice (GSI, including melt ponds and submerged ice), shadow, and ice/snow; (3) the polygon neighbor analysis separates melt ponds and submerged ice based on spatial relationship; and (4) pressure ridge features are extracted from shadow based on local illumination geometry. The producer's accuracy of 90.8% and user's accuracy of 91.8% are achieved for melt pond detection, and shadow shows a user's accuracy of 88.9% and producer's accuracies of 91.4%. Finally, pond density, pond fraction, ice floes, mean ice concentration, average ridge height, ridge profile, and ridge frequency are extracted from batch processing of aerial photos, and their uncertainties are estimated.

A combined basalt and peridotite perspective on 14 million years of melt generation at the Atlantis Bank segment of the Southwest Indian Ridge: Evidence for temporal changes in mantle dynamics?

USGS Publications Warehouse

Coogan, L.A.; Thompson, G.M.; MacLeod, C.J.; Dick, H.J.B.; Edwards, S.J.; Hosford, Scheirer A.; Barry, T.L.

2004-01-01

Little is known about temporal variations in melt generation and extraction at midocean ridges largely due to the paucity of sampling along flow lines. Here we present new whole-rock major and trace element data, and mineral and glass major element data, for 71 basaltic samples (lavas and dykes) and 23 peridotites from the same ridge segment (the Atlantis Bank segment of the Southwest Indian Ridge). These samples span an age range of almost 14 My and, in combination with the large amount of published data from this area, allow temporal variations in melting processes to be investigated. Basalts show systematic changes in incompatible trace element ratios with the older samples (from ???8-14 Ma) having more depleted incompatible trace element ratios than the younger ones. There is, however, no corresponding change in peridotite compositions. Peridotites come from the top of the melting column, where the extent of melting is highest, suggesting that the maximum degree of melting did not change over this interval of time. New and published Nd isotopic ratios of basalts, dykes and gabbros from this segment suggest that the average source composition has been approximately constant over this time interval. These data are most readily explained by a model in which the average source composition and temperature have not changed over the last 14 My, but the dynamics of mantle flow (active-to-passive) or melt extraction (less-to-more efficient extraction from the 'wings' of the melting column) has changed significantly. This hypothesised change in mantle dynamics occurs at roughly the same time as a change from a period of detachment faulting to 'normal' crustal accretion. We speculate that active mantle flow may impart sufficient shear stress on the base of the lithosphere to rotate the regional stress field and promote the formation of low angle normal faults. ?? 2004 Elsevier B.V. All rights reserved.

Molten uranium dioxide structure and dynamics

DOE PAGES

Skinner, L. B.; Parise, J. B.; Benmore, C. J.; ...

2014-11-21

Uranium dioxide (UO 2) is the major nuclear fuel component of fission power reactors. A key concern during severe accidents is the melting and leakage of radioactive UO 2 as it corrodes through its zirconium cladding and steel containment. Yet, the very high temperatures (>3140 kelvin) and chemical reactivity of molten UO 2 have prevented structural studies. In this work, we combine laser heating, sample levitation, and synchrotron x-rays to obtain pair distribution function measurements of hot solid and molten UO 2. The hot solid shows a substantial increase in oxygen disorder around the lambda transition (2670 K) but negligiblemore » U-O coordination change. On melting, the average U-O coordination drops from 8 to 6.7 ± 0.5. Molecular dynamics models refined to this structure predict higher U-U mobility than 8-coordinated melts.« less

High resolution melt curve analysis based on methylation status for human semen identification.

PubMed

Fachet, Caitlyn; Quarino, Lawrence; Karnas, K Joy

2017-03-01

A high resolution melt curve assay to differentiate semen from blood, saliva, urine, and vaginal fluid based on methylation status at the Dapper Isoform 1 (DACT1) gene was developed. Stains made from blood, saliva, urine, semen, and vaginal fluid were obtained from volunteers and DNA was isolated using either organic extraction (saliva, urine, and vaginal fluid) or Chelex ® 100 extraction (blood and semen). Extracts were then subjected to bisulfite modification in order to convert unmethylated cytosines to uracil, consequently creating sequences whose amplicons have melt curves that vary depending on their initial methylation status. When primers designed to amplify the promoter region of the DACT1 gene were used, DNA from semen samples was distinguishable from other fluids by a having a statistically significant lower melting temperature. The assay was found to be sperm-significant since semen from a vasectomized man produced a melting temperature similar to the non-semen body fluids. Blood and semen stains stored up to 5 months and tested at various intervals showed little variation in melt temperature indicating the methylation status was stable during the course of the study. The assay is a more viable method for forensic science practice than most molecular-based methods for body fluid stain identification since it is time efficient and utilizes instrumentation common to forensic biology laboratories. In addition, the assay is advantageous over traditional presumptive chemical methods for body fluid identification since results are confirmatory and the assay offers the possibility of multiplexing which may test for multiple body fluids simultaneously.

Paradise Lost: Uncertainties in melting and melt extraction processes beneath oceanic spreading ridges

NASA Astrophysics Data System (ADS)

Kelemen, P. B.

2014-12-01

In many ways, decompression melting and focused melt transport beneath oceanic spreading ridges is the best understood igneous process on Earth. However, there are remaining - increasing - uncertainties in interpreting residual mantle peridotites. Indicators of degree of melting in residual peridotite are questionable. Yb concentration and spinel Cr# are affected by (a) small scale variations in reactive melt transport, (b) variable extents of melt extraction, and (c) "impregnation", i.e. partial crystallization of cooling melt in pore space. Roughly 75% of abyssal peridotites have undergone major element refertilization. Many may have undergone several melting events. The following three statements are inconsistent: (1) Peridotite melt productivity beyond cpx exhaustion is > 0.1%/GPa. (2) Crustal thickness is independent of spreading rate at rates > 2 cm/yr full rate (excluding ultra-slow spreading ridges). (3) Thermal models predict, and observations confirm, thick thermal boundary layers beneath slow spreading ridges. If (a) melt productivity is << 0.1%/GPa beyond cpx-out, and (b) cpx-out occurs > 15 km below the seafloor beneath most ridges, then the independence of crustal thickness with spreading rate can be understood. Most sampled peridotites from ridges melted beyond cpx-out. Cpx in these rocks formed via impregnation and/or exsolution during cooling. Most peridotites beneath ridges may undergo cpx exhaustion during decompression melting. This would entail an upward modification of potential temperature estimates. Alternatively, perhaps oceanic crustal thickness does vary with spreading rate but this is masked by complicated tectonics and serpentinization at slow-spreading ridges. Dissolution channels (dunites) are predicted to coalesce downstream, but numerical models of these have not shown why > 95% of oceanic crust forms in a zone < 5 km wide. There may be permeability barriers guiding deeper melt toward the ridge, but field studies have not identified them. Permeable "shear bands" may guide melt to the ridge, but their nature in open systems at natural grain size and strain rates is uncertain. 2D and 3D focused solid upwelling due to melt buoyancy deep in the melting region, where pyroxenes are abundant and permeability is low, may warrant renewed attention.

Lithological, Chemical and Chronological Constraints on Melt Extraction from the Mantle Section of the ~492 Ma Shetland Ophiolite Complex, Scotland

NASA Astrophysics Data System (ADS)

O'Driscoll, B.; Walker, R. J.; Clay, P. L.; Day, J. M.; Ash, R. D.; Daly, J. S.

2015-12-01

The mantle sections of ophiolites offer a means of studying the composition and structure of the oceanic mantle. In particular, the relations between different lithologies can be established in the field, permitting an assessment of the relative timing of processes such as melt extraction and melt-rock reaction. The Shetland Ophiolite Complex (SOC) contains a well-preserved mantle section that is dominated by harzburgite (≥70 vol.%), with dominantly chondritic present-day 187Os/188Os compositions1. Melt extraction and melt-rock reaction is evident in the form of dunite and chromitite layers and lenses, with thicknesses ranging from millimetres-to-metres. These lithologies are characteristic of supra-subduction zone processing and are considered to relate to closure of the Iapetus Ocean at ~492 Ma1. However, evidence of much earlier melt extraction has been suggested for some SOC harzburgites, which have relatively unradiogenic 187Os/188Os compositions that yield TRD model ages as old as ~1.4 Ga1. In order to assess the scales at which such compositional heterogeneities are preserved in the mantle, a small (45 m2) area of the SOC mantle section was selected for detailed lithological mapping and sampling. A selection of harzburgites (n=8), dunites (n=6) and pyroxenites (n=2) from this area has been analysed for their Os isotope and highly-siderophile element (HSE) compositions. Six of the harzburgites and four of the dunites have relative HSE abundances and gOs values that are approximately chondritic, with gOs ranging only from -0.6 to +2.7 (n=10). Two dunites have more radiogenic gOs (up to +7.5), that is correlated with enhanced concentrations of accessory base-metal sulphides, suggesting formation via melt percolation and melt-rock reaction. The two remaining harzburgites have less radiogenic gOs (-3.5 and -4), yielding Mesoproterozoic TRD ages. The new data indicate that a comparable range of Os isotope compositions to that previously measured across the entire SOC mantle section is present in the mapped area, i.e., at the m2 scale, revealing the modest scale of isotopic and chemical heterogeneity in the oceanic mantle. 1O'Driscoll B, Day JMD, Walker RJ, Daly JS, McDonough WF, Piccoli PM (2012). Earth and Planetary Science Letters 333-334: 226-237.

Tin in granitic melts: The role of melting temperature and protolith composition

NASA Astrophysics Data System (ADS)

Wolf, Mathias; Romer, Rolf L.; Franz, Leander; López-Moro, Francisco Javier

2018-06-01

Granite bound tin mineralization typically is seen as the result of extreme magmatic fractionation and late exsolution of magmatic fluids. Mineralization, however, also could be obtained at considerably less fractionation if initial melts already had enhanced Sn contents. We present chemical data and results from phase diagram modeling that illustrate the dominant roles of protolith composition, melting conditions, and melt extraction/evolution for the distribution of Sn between melt and restite and, thus, the Sn content of melts. We compare the element partitioning between leucosome and restite of low-temperature and high-temperature migmatites. During low-temperature melting, trace elements partition preferentially into the restite with the possible exception of Sr, Cd, Bi, and Pb, that may be enriched in the melt. In high-temperature melts, Ga, Y, Cd, Sn, REE, Pb, Bi, and U partition preferentially into the melt whereas Sc, V, Cr, Co, Ni, Mo, and Ba stay in the restite. This contrasting behavior is attributed to the stability of trace element sequestering minerals during melt generation. In particular muscovite, biotite, titanite, and rutile act as host phases for Sn and, therefore prevent Sn enrichment in the melt as long as they are stable phases in the restite. As protolith composition controls both the mineral assemblage and modal contents of the various minerals, protolith composition eventually also controls the fertility of a rock during anatexis, restite mineralogy, and partitioning behavior of trace metals. If a particular trace element is sequestered in a phase that is stable during partial melting, the resulting melt is depleted in this element whereas the restite becomes enriched. Melt generation at high temperature may release Sn when Sn-hosts become unstable. If melt has not been lost before the breakdown of Sn-hosts, Sn contents in the melt will increase but never will be high. In contrast, if melt has been lost before the decomposition of Sn-hosts, the small volume of the high-temperature melt will not be diluted by low-temperature, low-Sn melts and, therefore, could have high Sn-contents. The combination of multiple melt extractions and Sn-mobilization at high temperature results in strong Sn enrichment in late, high-temperature melts. Metal enrichment during partial melting becomes particularly efficient, if the sedimentary protolith had experienced intense chemical alteration as the loss of Na and Ca together with a relative enrichment of K favors muscovite-rich metamorphic mineral assemblages that produce large amounts of melt during muscovite dehydration melting.

Effect of surfactant on single drop mass transfer for extraction of aromatics from lubricating oils

NASA Astrophysics Data System (ADS)

Izza, H.; Ben Abdessalam, S.; Korichi, M.

2018-03-01

Solvent extraction is an effective method for the reduction of the content of aromatic of lubricating oil. Frequently, with phenol, furfural, the NMP (out of N-methyl pyrrolidone). The power solvent and the selectivity can be still to increase while using surfactant as additive which facilitates the separation of phase and increases the yeild in raffinat. Liquid-liquid mass transfer coefficients for single freely rising drops in the presence of surfactant in an extraction column have been investigated. The surfactant used in this study was sodium lauryl ether sulfate (SLES). The experiments were performed by bubbling a solvent as a series of individual drops from the top of the column containing furfural-SLES solution. The column used in this experiment was made from glass with 17 mm inner diameter and a capacity of 125ml. The effects of the concentration of surfactant on the overall coefficient of mass transfer was investigated.

Thermo-rheological behaviour of polymer melts in microinjection moulding

NASA Astrophysics Data System (ADS)

Vasco, J. C.; Maia, J. M.; Pouzada, A. S.

2009-10-01

Microinjection has proven to be one of the most efficient replication methods for microcomponents and microsystems in various domains of microengineering. The use of available commercial microinjection equipment to evaluate the polymeric flow in microchannels would surely contribute to enhancing knowledge on polymeric flow at the microscale under industrial conditions. This approach is appropriate since rheological phenomena such as wall slip, surface tension, melt pressure drop and polymer flow length can be studied. These aspects are not fully dealt with in current commercial simulation software packages. In this study a micromould was designed to assess and characterize the flow in microchannels under realistic industrial conditions.

Empirical equation for predicting the surface tension of some liquid metals at their melting point

NASA Astrophysics Data System (ADS)

Ceotto, D.

2014-07-01

A new empirical equation is proposed for predicting the surface tension of some pure metals at their melting point. The investigation has been conducted adopting a statistical approach using some of the most accredited data available in literature. It is found that for Ag, Al, Au, Co, Cu, Fe, Ni, and Pb the surface tension can be conveniently expressed in function of the latent heat of fusion and of the geometrical parameters of an ideal liquid spherical drop. The equation proposed has been compared also with the model proposed by Lu and Jiang giving satisfactory agreement for the metals considered.

Melting and thermodynamic properties of pyrope (Mg3Al2Si3O12)

USGS Publications Warehouse

Tequi, C.; Robie, R.A.; Hemingway, B.S.; Neuville, D.R.; Richet, P.

1991-01-01

The heat capacity of Mg3Al2Si3O12 glass has been measured from 10 to 1000 K by adiabatic and differential scanning calorimetry. The heat capacity of crystalline pyrope has been determined from drop-calorimetry measurements between 820 and 1300 K. From these and previously published results a consistent set of thermodynamic data is presented for pyrope and Mg3Al2Si3O12 glass and liquid for the interval 0-2000 K. The enthalpy of fusion at 1570 ?? 30 K, the metastable congruent 1-bar melting point, is 241 ?? 12 kJ/mol. ?? 1991.

Experimental melting of phlogopite-bearing mantle at 1 GPa: Implications for potassic magmatism

NASA Astrophysics Data System (ADS)

Condamine, Pierre; Médard, Etienne

2014-07-01

We have experimentally investigated the fluid-absent melting of a phlogopite peridotite at 1.0 GPa (1000-1300 °C) to understand the source of K2O- and SiO2-rich magmas that occur in continental, post-collisional and island arc settings. Using a new extraction technique specially developed for hydrous conditions combined with iterative sandwich experiments, we have determined the composition of low- to high-degree melts (Φ=1.4 to 24.2 wt.%) of metasomatized lherzolite and harzburgite sources. Due to small amounts of adsorbed water in the starting material, amphibole crystallized at the lowest investigated temperatures. Amphibole breaks down at 1050-1075 °C, while phlogopite-breakdown occurs at 1150-1200 °C. This last temperature is higher than the previously determined in a mantle assemblage, due to the presence of stabilizing F and Ti. Phlogopite-lherzolite melts incongruently according to the continuous reaction: 0.49 phlogopite + 0.56 orthopyroxene + 0.47 clinopyroxene + 0.05 spinel = 0.58 olivine + 1.00 melt. In the phlogopite-harzburgite, the reaction is: 0.70 phlogopite + 1.24 orthopyroxene + 0.05 spinel = 0.99 olivine + 1.00 melt. The K2O content of water-undersaturated melts in equilibrium with residual phlogopite is buffered, depending on the source fertility: from ∼3.9 wt.% in lherzolite to ∼6.7 wt.% in harzburgite. Primary melts are silica-saturated and evolve from trachyte to basaltic andesite (63.5-52.1 wt.% SiO2) with increasing temperature. Calculations indicate that such silica-rich melts can readily be extracted from their mantle source, due to their low viscosity. Our results confirm that potassic, silica-rich magmas described worldwide in post-collisional settings are generated by melting of a metasomatized phlogopite-bearing mantle in the spinel stability field.

Direct immersion single drop micro-extraction method for multi-class pesticides analysis in mango using GC-MS.

PubMed

Pano-Farias, Norma S; Ceballos-Magaña, Silvia G; Muñiz-Valencia, Roberto; Jurado, Jose M; Alcázar, Ángela; Aguayo-Villarreal, Ismael A

2017-12-15

Due the negative effects of pesticides on environment and human health, more efficient and environmentally friendly methods are needed. In this sense, a simple, fast, free from memory effects and economical direct-immersion single drop micro-extraction (SDME) method and GC-MS for multi-class pesticides determination in mango samples was developed. Sample pre-treatment using ultrasound-assisted solvent extraction and factors affecting the SDME procedure (extractant solvent, drop volume, stirring rate, ionic strength, time, pH and temperature) were optimized using factorial experimental design. This method presented high sensitive (LOD: 0.14-169.20μgkg -1 ), acceptable precision (RSD: 0.7-19.1%), satisfactory recovery (69-119%) and high enrichment factors (20-722). Several obtained LOQs are below the MRLs established by the European Commission; therefore, the method could be applied for pesticides determination in routing analysis and custom laboratories. Moreover, this method has shown to be suitable for determination of some of the studied pesticides in lime, melon, papaya, banana, tomato, and lettuce. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ultrasonic nebulization extraction-heating gas flow transfer-headspace single drop microextraction of essential oil from pericarp of Zanthoxylum bungeanum Maxim.

PubMed

Wei, Shigang; Zhang, Huihui; Wang, Yeqiang; Wang, Lu; Li, Xueyuan; Wang, Yinghua; Zhang, Hanqi; Xu, Xu; Shi, Yuhua

2011-07-22

The ultrasonic nebulization extraction-heating gas flow transfer coupled with headspace single drop microextraction (UNE-HGFT-HS-SDME) was developed for the extraction of essential oil from Zanthoxylum bungeanum Maxim. The gas chromatography-mass spectrometry was applied to the determination of the constituents in the essential oil. The contents of the constituents from essential oil obtained by the proposed method were found to be more similar to those obtained by hydro-distillation (HD) than those obtained by ultrasonic nebulization extraction coupled with headspace single drop microextraction (UNE-HS-SDME). The heating gas flow was firstly used in the analysis of the essential oil to transfer the analytes from the headspace to the solvent microdrop. The relative standard deviations for determining the five major constituents were in the range from 1.5 to 6.7%. The proposed method is a fast, sensitive, low cost and small sample consumption method for the determination of the volatile and semivolatile constituents in the plant materials. Copyright © 2011 Elsevier B.V. All rights reserved.

Impurity segregation behavior in polycrystalline silicon ingot grown with variation of electron-beam power

NASA Astrophysics Data System (ADS)

Lee, Jun-Kyu; Lee, Jin-Seok; Jang, Bo-Yun; Kim, Joon-Soo; Ahn, Young-Soo; Cho, Churl-Hee

2014-08-01

Electron beam melting (EBM) systems have been used to improve the purity of metallurgical grade silicon feedstock for photovoltaic application. Our advanced EBM system is able to effectively remove volatile impurities using a heat source with high energy from an electron gun and to continuously allow impurities to segregate at the top of an ingot solidified in a directional solidification (DS) zone in a vacuum chamber. Heat in the silicon melt should move toward the ingot bottom for the desired DS. However, heat flux though the ingot is changed as the ingot becomes longer due to low thermal conductivity of silicon. This causes a non-uniform microstructure of the ingot, finally leading to impurity segregation at its middle. In this research, EB power irradiated on the silicon melt was controlled during the ingot growth in order to suppress the change of heat flux. EB power was reduced from 12 to 6.6 kW during the growth period of 45 min with a drop rate of 0.125 kW/min. Also, the silicon ingot was grown under a constant EB power of 12 kW to estimate the effect of the drop rate of EB power. When the EB power was reduced, the grains with columnar shape were much larger at the middle of the ingot compared to the case of constant EB power. Also, the present research reports a possible reason for the improvement of ingot purity by considering heat flux behaviors.

Electronic and structural transitions in dense liquid sodium.

PubMed

Raty, Jean-Yves; Schwegler, Eric; Bonev, Stanimir A

2007-09-27

At ambient conditions, the light alkali metals are free-electron-like crystals with a highly symmetric structure. However, they were found recently to exhibit unexpected complexity under pressure. It was predicted from theory--and later confirmed by experiment--that lithium and sodium undergo a sequence of symmetry-breaking transitions, driven by a Peierls mechanism, at high pressures. Measurements of the sodium melting curve have subsequently revealed an unprecedented (and still unexplained) pressure-induced drop in melting temperature from 1,000 K at 30 GPa down to room temperature at 120 GPa. Here we report results from ab initio calculations that explain the unusual melting behaviour in dense sodium. We show that molten sodium undergoes a series of pressure-induced structural and electronic transitions, analogous to those observed in solid sodium but commencing at much lower pressure in the presence of liquid disorder. As pressure is increased, liquid sodium initially evolves by assuming a more compact local structure. However, a transition to a lower-coordinated liquid takes place at a pressure of around 65 GPa, accompanied by a threefold drop in electrical conductivity. This transition is driven by the opening of a pseudogap, at the Fermi level, in the electronic density of states--an effect that has not hitherto been observed in a liquid metal. The lower-coordinated liquid emerges at high temperatures and above the stability region of a close-packed free-electron-like metal. We predict that similar exotic behaviour is possible in other materials as well.

Probing the nanoscale with high-speed interferometry of an impacting drop

NASA Astrophysics Data System (ADS)

Thoroddsen, S. T.; Li, E. Q.; Vakarelski, I. U.; Langley, K.

2017-02-01

The simple phenomenon of a water drop falling onto a glass plate may seem like a trivial fluid mechanics problem. However, detailed imaging has shown that this process is highly complex and a small air-bubble is always entrapped under the drop when it makes contact with the solid. This bubble can interfere with the uniformity of spray coatings and degrade inkjet fabrication of displays etc. We will describe how we use high-speed interferometry at 5 million frames per second to understand the details of this process. As the impacting drop approaches the solid, the dynamics are characterized by a balance between the lubrication pressure in the thin air layer and the inertia of the bot-tom of the drop. This deforms the drop, forming a dimple at its bottom and making the drop touch the surface along a ring, thereby entrapping the air-layer, which is typically 1-3 μm thick. This air-layer can be highly compressed and the deceleration of the bottom of the drop can be as large as 300,000 g. We describe how the thickness evolution of the lubricating air-layer is extracted from following the interference fringes between frames. Two-color interferometry is also used to extract absolute layer thicknesses. Finally, we identify the effects of nanometric surface roughness on the first contact of the drop with the substrate. Here we need to resolve the 100 nm thickness changes occurring during 200 ns intervals, requiring these state of the art high-speed cameras. Surprisingly, we see a ring of micro-bubbles marking the first contact of the drop with the glass, only for microscope slides, which have a typical roughness of 20 nm, while such rings are absent for drop impacts onto molecularly smooth mica surfaces.

Thermal Convection in High-Pressure Ice Layers Beneath a Buried Ocean within Titan and Ganymede

NASA Astrophysics Data System (ADS)

Tobie, G.; Choblet, G.; Dumont, M.

2014-12-01

Deep interiors of large icy satellites such as Titan and Ganymede probably harbor a buried ocean sandwiched between low pressure ice and high-pressure ice layers. The nature and location of the lower interface of the ocean involves equilibration of heat and melt transfer in the HP ices and is ultimately controlled by the amount heat transferred through the surface ice Ih layer. Here, we perform 3D simulations of thermal convection, using the OEDIPUS numerical tool (Choblet et al. GJI 2007), to determine the efficiency of heat and mass transfer through these HP ice mantles. In a first series of simulations with no melting, we show that a significant fraction of the HP layer reaches the melting point. Using a simple description of water production and transport, our simulations demonstrate that the melt generation in the outermost part of the HP ice layer and its extraction to the overlying ocean increase the efficiency of heat transfer and reduce strongly the internal temperature. structure and the efficiency of the heat transfer. Scaling relationships are proposed to describe the cooling effect of melt production/extraction and used to investigate the consequences of internal melting on the thermal history of Titan and Ganymede's interior.

LSA Large Area Silicon Sheet Task Continuous Czochralski Process Development

NASA Technical Reports Server (NTRS)

Rea, S. N.

1979-01-01

A commercial Czochralski crystal growing furnace was converted to a continuous growth facility by installation of a small, in-situ premelter with attendant silicon storage and transport mechanisms. Using a vertical, cylindrical graphite heater containing a small fused quartz test tube linear from which the molten silicon flowed out the bottom, approximately 83 cm of nominal 5 cm diamter crystal was grown with continuous melt addition furnished by the test tube premelter. High perfection crystal was not obtained, however, due primarily to particulate contamination of the melt. A major contributor to the particulate problem was severe silicon oxide buildup on the premelter which would ultimately drop into the primary melt. Elimination of this oxide buildup will require extensive study and experimentation and the ultimate success of continuous Czochralski depends on a successful solution to this problem. Economically, the continuous Czochralski meets near-term cost goals for silicon sheet material.

Peak effect versus skating in high-temperature nanofriction

NASA Astrophysics Data System (ADS)

Zykova-Timan, T.; Ceresoli, D.; Tosatti, E.

2007-03-01

The physics of sliding nanofriction at high temperature near the substrate melting point, TM, is so far unexplored. We conducted simulations of hard tips sliding on a prototype non-melting surface, NaCl(100), revealing two distinct and opposite phenomena for ploughing and for grazing friction in this regime. We found a frictional drop close to TM for deep ploughing and wear, but on the contrary a frictional rise for grazing, wearless sliding. For both phenomena, we obtain a fresh microscopic understanding, relating the former to `skating' through a local liquid cloud, and the latter to linear response properties of the free substrate surface. We argue that both phenomena occur more generally on surfaces other than NaCl and should be pursued experimentally. Most metals, in particular those possessing one or more close-packed non-melting surfaces, such as Pb, Al or Au(111), are likely to behave similarly.

Ice Melting to Release Reactants in Solution Syntheses.

PubMed

Wei, Hehe; Huang, Kai; Zhang, Le; Ge, Binghui; Wang, Dong; Lang, Jialiang; Ma, Jingyuan; Wang, Da; Zhang, Shuai; Li, Qunyang; Zhang, Ruoyu; Hussain, Naveed; Lei, Ming; Liu, Li-Min; Wu, Hui

2018-03-19

Aqueous solution syntheses are mostly based on mixing two solutions with different reactants. It is shown that freezing one solution and melting it in another solution provides a new interesting strategy to mix chemicals and to significantly change the reaction kinetics and thermodynamics. For example, a precursor solution containing a certain concentration of AgNO 3 was frozen and dropped into a reductive NaBH 4 solution at about 0 °C. The ultra-slow release of reactants was successfully achieved. An ice-melting process can be used to synthesize atomically dispersed metals, including cobalt, nickel, copper, rhodium, ruthenium, palladium, silver, osmium, iridium, platinum, and gold, which can be easily extended to other solution syntheses (such as precipitation, hydrolysis, and displacement reactions) and provide a generalized method to redesign the interphase reaction kinetics and ion diffusion in wet chemistry. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dynamic Response of a High Arctic Glacier to Melt and Runoff Variations

NASA Astrophysics Data System (ADS)

van Pelt, Ward J. J.; Pohjola, Veijo A.; Pettersson, Rickard; Ehwald, Lena E.; Reijmer, Carleen H.; Boot, Wim; Jakobs, Constantijn L.

2018-05-01

The dynamic response of High Arctic glaciers to increased runoff in a warming climate remains poorly understood. We analyze a 10-year record of continuous velocity data collected at multiple sites on Nordenskiöldbreen, Svalbard, and study the connection between ice flow and runoff within and between seasons. During the melt season, the sensitivity of ice motion to runoff at sites in the ablation and lower accumulation zone drops by a factor of 3 when cumulative runoff exceeds a local threshold, which is likely associated with a transition from inefficient (distributed) to efficient (channelized) drainage. Average summer (June-August) velocities are found to increase with summer ablation, while subsequent fall (September-November) velocities decrease. Spring (March-May) velocities are largely insensitive to summer ablation, which suggests a short-lived impact of summer melt on ice flow during the cold season. The net impact of summer ablation on annual velocities is found to be insignificant.

Molecular dynamics study of the vaporization of an ionic drop.

PubMed

Galamba, N

2010-09-28

The melting of a microcrystal in vacuum and subsequent vaporization of a drop of NaCl were studied through molecular dynamics simulations with the Born-Mayer-Huggins-Tosi-Fumi rigid-ion effective potential. The vaporization was studied for a single isochor at increasing temperatures until the drop completely vaporized, and gaseous NaCl formed. Examination of the vapor composition shows that the vapor of the ionic drop and gaseous NaCl are composed of neutral species, the most abundant of which, ranging from simple NaCl monomers (ion pairs) to nonlinear polymers, (Na(n)Cl(n))(n=2-4). The enthalpies of sublimation, vaporization, and dissociation of the different vapor species are found to be in reasonable agreement with available experimental data. The decrease of the enthalpy of vaporization of the vapor species, with the radius of the drop decrease, accounts for a larger fraction of trimers and tetramers than that inferred from experiments. Further, the rhombic dimer is significantly more abundant than its linear isomer although the latter increases with the temperature. The present results suggest that both trimers and linear dimers may be important to explain the vapor pressure of molten NaCl at temperatures above 1500 K.

Evolving magma storage conditions beneath Mount St. Helens inferred from chemical variations in melt inclusions from the 1980-1986 and current (2004-2006) eruptions: Chapter 33 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

USGS Publications Warehouse

Blundy, Jon; Cashman, Katharine V.; Berlo, Kim; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

2008-01-01

O contents, consistent with magma extraction from shallow depths. Highly enriched Li in melt inclusions suggests that vapor transport of Li is a characteristic feature of Mount St. Helens. Melt inclusions from the current eruption have subtly different trace-element chemistry from all but one of the 1980-86 melt inclusions, with steeper rareearth-element (REE) patterns and low U, Th, and high-fieldstrength elements (HFSE), indicating addition of a new melt component to the magma system. It is anticipated that increasing involvement of the new melt component will be evident as the current eruption proceeds.

Extraction of essential oil from Bunium Persicum (Boiss.) by instant controlled pressure drop (DIC).

PubMed

Feyzi, Elnaz; Eikani, Mohammad H; Golmohammad, Fereshteh; Tafaghodinia, Bahram

2017-12-29

Essential oils extraction from Bunium Persicum (Boiss) was performed using instant controlled pressure drop (in French: Détente Instantanée Contrôlée or DIC) thechnology and optimum extraction conditions were obtained. Response surface methodology (RSM) was used to determine the optimal conditions and the results were 20s heating time, 3.5bar pressure, 0.44mm particle diameter and 9 cycles. Essential oils extraction was also compared with Hydrodistillation (HD), ultrasound-assisted extraction (UAE) and Soxhlet (SOX) extraction. Results show higher efficiency of the DIC than other methods and more oxygenated components were observed. Impact of DIC, HD, UAE and SOX on the morphological structure of the plant was studied by SEM. Antioxidant activity and total phenolic content (TPC) of the extract were determined and comapred by HD. Results show that DIC facilitates achieving to higher TPC and more antioxidant activity. Copyright © 2017 Elsevier B.V. All rights reserved.

Dynamic ultrasonic nebulisation extraction coupled with headspace ionic liquid-based single-drop microextraction for the analysis of the essential oil in Forsythia suspensa.

PubMed

Yang, Jinjuan; Wei, Hongmin; Teng, Xiane; Zhang, Hanqi; Shi, Yuhua

2014-01-01

Ionic liquids have attracted much attention as an extraction solvent instead of traditional organic solvent in single-drop microextraction. However, non-volatile ionic liquids are difficult to couple with gas chromatography. Thus, the following injection system for the determination of organic compounds is described. To establish an environmentally friendly, simple, and effective extraction method for preparation and analysis of the essential oil from aromatic plants. The dynamic ultrasonic nebulisation extraction was coupled with headspace ionic liquid-based single-drop microextraction(UNE-HS/IL/SDME)for the extraction of essential oils from Forsythia suspense fruits. After 13 min of extraction for 50 mg sample, the extracts in ionic liquid were evaporated rapidly in the gas chromatography injector through a thermal desorption unit (5 s). The traditional extraction method was carried out for comparative study. The optimum conditions were: 3 μL of 1-methyl-3-octylimidazolium hexafluorophosphate was selected as the extraction solvent, the sample amount was 50 mg, the flow rate of purging gas was 200 mL/min, the extraction time was 13 min, the injection volume was 2 μL, and the thermal desorption temperature and time were 240 °C and 5 s respectively. Comparing with hydrodistillation (HD), the proposed method was environment friendly and efficient. The proposed method is environmentally friendly, time saving, with high efficiency and low consumption. It would extend the application range of the HS/SDME and would be useful especially for aromatic plants analysis. Copyright © 2013 John Wiley & Sons, Ltd.

High porosity harzburgite and dunite channels for the transport of compositionally heterogeneous melts in the mantle: II. Geochemical consequences

NASA Astrophysics Data System (ADS)

Liang, Y.; Schiemenz, A.; Xia, Y.; Parmentier, E.

2009-12-01

In a companion numerical study [1], we explored the spatial distribution of high porosity harzburgite and dunite channels produced by reactive dissolution of orthopyroxene (opx) in an upwelling mantle column and identified a number of new features. In this study, we examine the geochemical consequences of channelized melt flow under the settings outlined in [1] with special attention to the transport of compositionally heterogeneous melts and their interactions with the surrounding peridotite matrix during melt migration in the mantle. Time-dependent transport equations for a trace element in the interstitial melt and solids that include advection, dispersion, and melt-rock reaction were solved in a 2-D upwelling column using the high-order numerical methods outlined in [1]. The melt and solid velocities were taken from the steady state or quasi-steady state solutions of [1]. In terms of trace element fractionation, the simulation domain can be divided into 4 distinct regions: (a) high porosity harzburgite channel, overlain by; (b) high porosity dunite channel; (c) low porosity compacting boundary layer surrounding the melt channels; and (d) inter-channel regions outside (c). In the limit of local chemical equilibrium, melting in region (d) is equivalent to batch melting, whereas melting and melt extraction in (c) is more close to fractional melting with the melt suction rate first increase from the bottom of the melting column to a maximum near the bottom of the dunite channel and then decrease upward in the compacting boundary layer. The melt composition in the high porosity harzburgite channel is similar to that produced by high-degree batch melting (up to opx exhaustion), whereas the melt composition in the dunite is a weighted average of the ultra-depleted melt from the harzburgite channel below, the expelled melt from the compacting boundary layer, and melt produced by opx dissolution along the sidewalls of the dunite channel. Compaction within the dunite channel drives part of the channel melt in the upper part of the dunite channel into the surrounding harzburgite, providing a physical mechanism for shallow level re-fertilization or mantle metasomatism. The presence of compacting waves in and around a dunite-harzburgite channel system further complicates the melt flow field and provides new mechanisms for melt-peridotite interaction in the mantle. In the presence of chemical heterogeneity, the assumption of local equilibrium between the melt and its surrounding crystals results in significant chromatographic fractionation for incompatible trace elements in the melt percolating in region (d), and moderate fractionation for melt flowing through the harzburgite channel. Chemical disequilibrium between the melt and crystals reduces the extent of chromatographic fractionation during melt percolation and may be needed to explain the observed geochemical data. Alternatively, compositionally heterogeneous melts may be extracted through the high porosity melt channels without interaction with the peridotite matrix. [1] Schiemenz et al. submitted to AGU Fall meeting, 2009.

Electrodialytic extraction of anionic pharmaceutical compounds from a single drop of whole blood using a supported liquid membrane.

PubMed

Imoto, Yurika; Nishiyama, Hiroka; Nakamura, Yukihide; Ohira, Shin-Ichi; Toda, Kei

2018-05-01

A method to introduce target analytes to a chromatograph from a single drop of whole blood was investigated for minimally invasive monitoring of anionic pharmaceuticals. In this work, salicylate and loxoprofen were examined as organic anions. A micro ion extractor (MIE) has been developed for extraction of inorganic trace anions from whole blood, but this device is not suitable for extraction of pharmaceuticals. In the present study, we improved and optimized the MIE device for organic anion extraction. Various supported liquid membranes were evaluated for use as the ion transfer membrane, with each membrane placed between a droplet sample (donor) and an acceptor solution. A supported liquid membrane of porous polypropylene impregnated with 1-butanol was selected. In addition, the methods for electric field creation and electrode contact were examined to improve the characteristics of the MIE device. The current and extraction time were also optimized. With the optimized method, salicylate and loxoprofen were successfully extracted from a single drop of whole blood. Changes in the concentrations of these pharmaceuticals in blood over time were monitored after administration. As only 25μL of whole blood was required for analysis, repeat measurements could be conducted to monitor changes in the concentrations. This MIE will be useful for monitoring pharmaceutical concentrations in blood. Copyright © 2018 Elsevier B.V. All rights reserved.

Zn isotopic heterogeneity in the mantle: A melting control?

NASA Astrophysics Data System (ADS)

Doucet, Luc S.; Mattielli, Nadine; Ionov, Dmitri A.; Debouge, Wendy; Golovin, Alexander V.

2016-10-01

We present new Zn elemental and isotope data on seventeen fertile and refractory mantle peridotite xenoliths. Eleven fertile peridotites are garnet and spinel lherzolites from Vitim and Tariat (Siberia and Mongolia) and represent some of the most pristine fertile peridotites available. Six refractory peridotites are spinel harzburgites from the Udachnaya kimberlite (Siberian craton) that are nearly pristine residues of high-degree polybaric melting at high pressure (7-4 GPa). Geochemical data suggest that Zn isotopic compositions in the peridotites have not been affected by post-melting processes such as metasomatism, contamination by the host-magmas or alteration. The fertile peridotites have uniform Zn concentrations (59 ± 2 ppm) and Zn isotopic compositions with δ66Zn (relative to JMC-Lyon-03-0749l) = +0.30 ± 0.03‰ consistent with the Bulk Silicate Earth estimates of δ66Zn = +0.28 ± 0.05‰ (Chen et al., 2013). The refractory peridotites have Zn concentrations ranging from 30 to 48 ppm and δ66Zn from + 0.10 ± 0.01 ‰ to + 0.18 ± 0.01 ‰ with an average of + 0.14 ± 0.03 ‰. Our data suggest that the lithospheric mantle has a heterogeneous Zn isotopic composition. Modeling of Zn isotope partitioning during partial melting of fertile mantle suggests that high degrees of melt extraction (>30%) may significantly fractionate Zn isotopes (up to 0.16‰) and that during mantle melting, Zn concentrations and isotopic compositions are mainly controlled by the stability of clinopyroxene and garnet within the melting residue. Because the stability of clinopyroxene and garnet is mainly pressure dependent we suggest that both the depth and the degrees of melt extraction may control Zn isotope fractionation during mantle melting.

Formation and metasomatism of continental lithospheric mantle in intra-plate and subduction-related tectonic settings

NASA Astrophysics Data System (ADS)

Ionov, Dmitri

2010-05-01

Our knowledge of the origin and evolution of the continental lithospheric mantle (CLM) remains fragmentary and partly controversial in spite of recent advances in petrologic, geochemical and geophysical studies of the deep Earth and experimental work. Debate continues on a number of essential topics, like relative contributions of partial melting, metasomatism and ‘re-fertilisation' as well as the timing, conditions and tectonic settings of those processes. These topics can be addressed by studies of ultramafic xenoliths in volcanic rocks which arguably provide the least altered samples of modern and ancient CLM. The subcontinental lithosphere is thought to be a mantle region from which melts have been extracted, thus making the lithosphere more refractory. Melting degrees can be estimated from Al contents while the depth of melt extraction can be assessed from Al-Fe (Mg#) relations in unmetasomatized melting residues in comparison with experimental data, e.g. [1]. High silica and opx in the residues may indicate melting in water-rich conditions. High-precision Mg# and Mn for olivine may constrain degrees and conditions of partial melting and/or metasomatism, tectonic settings, modal compositions (e.g. presence of garnet) and equilibration conditions of mantle peridotites [2]. These estimates require both adequate sampling and high-quality major element and modal data; sampling and analytical uncertainties in published work may contribute substantially to chemical heterogeneities (and different origins) inferred for CLM domains [3]. Very fertile peridotite xenolith suites are rare worldwide [3]. They were initially viewed as representing mantle domains that experienced only very small degrees of melt extraction but are attributed by some workers to ‘refertilization' of refractory mantle by percolating asthenospheric melts. Such alternative mechanisms might be valid for some rare hybrid and Fe-enriched peridotites but they fail to comprehensively explain modal, major and trace element and isotope compositions of fertile lherzolites and thus cannot provide viable alternatives to the concept of melt extraction from pristine mantle as the major mechanism of CLM formation. Published data on xenoliths from andesitic volcanoes and on supra-subduction oceanic peridotites [4] show that the most common rocks in mantle wedge lithosphere are highly refractory harzburgites characterized by a combination of variable but generally high modal opx (18-30%) with very low modal cpx (1.5-3%). At a given olivine (or MgO) content, they have higher opx and silica, and lower cpx, Al and Ca contents than normal refractory peridotite xenoliths in continental basalts; the Mg-Si and Al-Si trends in those rocks resemble those in cratonic peridotites. These features may indicate either fluid fluxing during melting in the mantle wedge or selective post-melting metasomatic enrichments in silica to transform some olivine to opx. High oxygen fugacities and radiogenic Os-isotope compositions in those rocks may be related to enrichments by slab-derived fluids, but these features are not always coupled with trace element enrichments or patterns commonly attributed to "subduction zone metasomatism" deduced from studies of arc volcanic rocks and experiments. The valuable insights provided by experimental work and xenolith case studies are difficult to apply to many natural peridotite series because late-stage processes commonly overlap the evidence for initial melting. References: [1] Herzberg C., J. Petrol. 45: 2507 (2004). [2] Ionov D. & Sobolev A., GCA 72 (S1): A410 (2008). [3] Ionov D., Contrib. Miner. Petrol. (2007) [4] Ionov D., J. Petrol. doi: 10.1093/petrology/egp090 (2010)

Determination of trihalomethanes in waters by ionic liquid-based single drop microextraction/gas chromatographic/mass spectrometry.

PubMed

Aguilera-Herrador, Eva; Lucena, Rafael; Cárdenas, Soledad; Valcárcel, Miguel

2008-10-31

A simple, rapid, solventless method for the determination of trihalomethanes (THMs) (chloroform, bromodichloromethane, dibromochloromethane and bromoform) in water samples is presented. The analytes are extracted from the headspace of the aqueous matrix into a 2 microL drop of the ionic liquid 1-octyl-3-methyl-imidazolium hexafluorophosphate working at 30 degrees C for 30 min. The separation and detection of the target compounds is accomplished by gas chromatography/mass spectrometry owing to the use of an interface that efficiently transfers the analytes extracted in the ionic liquid drop to the gas chromatograph while preventing the ionic liquid from entering the column. The detection limits obtained are below the values compelled by the legislation, ranging from 0.5 microg L(-1) for chloroform and bromodichloromethane to 0.9 microg L(-1) for dibromochloromethane. The use of ionic liquid in the extraction procedure avoids the use of organic solvents and leads to relative standard deviations that range from 3.1% to 4.8%.

Gas-Bearing Crucible for Shot Tower

NASA Technical Reports Server (NTRS)

Youngberg, C. L.; Miller, C. G.; Stephens, J. B.; Finnerty, A. A.

1983-01-01

Device protects molten drops from contamination and distortion. Gas flowing through levitator tube levitates small balls while they melt. Gas heated by filament extending through center of tube. Gas bearing crucible on tube has concave configuration to hold single relatively large ball or many recesses to hold many small balls. By time spheres reach foam, they are cooled sufficiently by radiation to retain their shape.

Determination of surface energies of hot-melt extruded sugar-starch pellets.

PubMed

Yeung, Chi-Wah; Rein, Hubert

2018-02-01

Hot-melt extruded sugar-starch pellets are an alternative for commercial sugar spheres, but their coating properties remain to be studied. Both the European Pharmcopoeia 8.6 and the United States Pharmacopoeia 40 specify the composition of sugar-starch pellets without giving requirements for the manufacturing process. Due to various fabrication techniques, the physicochemical properties of pellets may differ. Therefore, the adhesion energies of three coating dispersions (sustained, enteric and immediate release) on different types of pellets were investigated. In this context, the surface energies of various kinds of corn starch (normal, waxy, high-amylose) and sucrose pellets were analyzed using the sessile drop method, whereas the surface tensions of the coating dispersions were examined using the pendant drop method. The adhesion forces were calculated from the results of these studies. Furthermore, sugar spheres were characterized in terms of particle size distribution, porosity and specific surface area. An increase of the pellets' sucrose content leads to a more porous surface structure, which gives them an enhanced wetting behavior with coating dispersions. The adhesion energies of extruded sugar-starch pellets are similar to those of commercial sugar spheres, which comply with pharmacopeial requirements. Both types of pellets are equally suited for coating.

Melting of the Dipalmitoylphosphatidylcholine Monolayer.

PubMed

Xu, Lu; Bosiljevac, Gordon; Yu, Kyle; Zuo, Yi Y

2018-04-17

Langmuir monolayer self-assembled at the air-water interface represents an excellent model for studying phase transition and lipid polymorphism in two dimensions. Compared with numerous studies of phospholipid phase transitions induced by isothermal compression, there are very scarce reports on two-dimensional phase transitions induced by isobaric heating. This is mainly due to technical difficulties of continuously regulating temperature variations while maintaining a constant surface pressure in a classical Langmuir-type film balance. Here, with technological advances in constrained drop surfactometry and closed-loop axisymmetric drop shape analysis, we studied the isobaric heating process of the dipalmitoylphosphatidylcholine (DPPC) monolayer. It is found that temperature and surface pressure are two equally important intensive properties that jointly determine the phase behavior of the phospholipid monolayer. We have determined a critical point of the DPPC monolayer at a temperature of 44 °C and a surface pressure of 57 mN/m. Beyond this critical point, no phase transition can exist in the DPPC monolayer, either by isothermal compression or by isobaric heating. The melting process of the DPPC monolayer studied here provides novel insights into the understanding of a wide range of physicochemical and biophysical phenomena, such as surface thermodynamics, critical phenomena, and biophysical study of pulmonary surfactants.

The effects of sulfide composition on the solubility of sulfur in coexisting silicate melts

NASA Astrophysics Data System (ADS)

Smythe, Duane; Wood, Bernard; Kiseeva, Ekaterina

2016-04-01

The extent to which sulfur dissolves in silicate melts saturated in an immiscible sulfide phase is a fundamental question in igneous petrology and plays a primary role in the generation of magmatic ore deposits, volcanic degassing and planetary differentiation. Terrestrial sulfide melts often contain over 20 weight percent Ni + Cu, however, most experimental studies investigating sulfur solubility in silicate melt have been primarily concerned with the effects of silicate melt composition, and pure FeS has been use as the immiscible sulfide melt (O'Neill and Mavrogenes, 2002; Li and Ripley, 2005). To investigation of the effects of sulfide composition, in addition to those of temperature, pressure and silicate melt composition, on sulfur solubility in silicate melts, we have carried out a series of experiments done at pressures between 1.5 and 3 GPa and temperatures from 1400 to 1800C over a range of compositions of both the silicate and sulfide melt. We find that the solubility of sulfur in silicate melts drops significantly with the substitution of Ni and Cu for Fe in the immiscible sulfide melt, decreasing by approximately 40% at mole fractions of NiS + Cu2S of 0.4. Combining our results with those from the previous studies investigating sulfur solubility in silicate melts we have also found that solubility increases with increasing temperature and decreases pressure. These results show that without considering the composition of the immiscible sulfide phase the sulfur content of silicate melts can be significantly overestimated. This may serve to explain the relatively low sulfur concentrations in MORB melts, which previous models predict to be undersaturated in a sulfide phase despite showing chemical and textural evidence for sulfide saturation. Li, C. & Ripley, E. M. (2005). Empirical equations to predict the sulfur content of mafic magmas at sulfide saturation and applications to magmatic sulfide deposits. Mineralium Deposita 40, 218-230. O'Neill, H. S. C. & Mavrogenes, J. A. (2002). The Sulfide Capacity and the Sulfur Content at Sulfide Saturation of Silicate Melts at 1400°C and 1 bar. Journal of Petrology 43, 1049-1087.

Variations in mid-ocean ridge magmatism and carbon emissions driven by glacial cycles

NASA Astrophysics Data System (ADS)

Katz, R. F.; Burley, J. M.; Huybers, P. J.; Langmuir, C. H.; Crowley, J. W.; Park, S. H.; Carbotte, S. M.; Ferguson, D.; Proistosescu, C.; Boulahanis, B.

2015-12-01

Glacial cycles transfer ˜5×10^19 kg of water between the oceans and ice sheets, causing pressure changes in the upper mantle with consequences for the melting of Earth's interior. Forced with Plio-Pleistocene sea-level variations, theoretical models of mid-ocean ridge magma/mantle dynamics predict temporal variations up to 10% in melt supply to the base of the crust. Moreover, a transport model for a perfectly incompatible element suggests that CO2 emissions from mid-ocean ridges could vary by a similar proportion, though with a longer time-lag.Bathymetry from the Australian-Antarctic ridge shows statistically significant spectral energy near the Milankovitch periods of 23, 41, and 100 thousand years, which is consistent with model predictions. These results suggest that abyssal hills record the magmatic response to changes in sea level. The mechanism by which variations in the rate of melt supply are expressed in the bathymetry is not understood.The same pressure variations that modulate the melting rate could also modulate the depth of the onset of silicate melting. As ice sheets grow and sea level drops, this onset deepens, causing melting at the base of the silicate melting regime. Excess highly incompatible elements like CO2 enter the melt and begin their journey to the ridge axis. Tens of thousands of years later, this additional CO2 flux is emitted into the climate system. Because of its delay with respect to sea-level change, the predicted variation in CO2 emissions could represent a restoring force on climate (and sea-level) excursions. This mechanism has a response time determined by the time scale of melt transport; it potentially introduces a resonant frequency into the climate system.

A multiphysics phase field model on melting and kinetic superheating of aluminum nanolayer and nanoparticle

NASA Astrophysics Data System (ADS)

Hwang, Yong Seok

It has been found during the last decade that a nanoscale melting of metal has very distinctive features compared to its microscale counterpart. It has been observed that a highly non-equilibrium state can result in extreme superheating of a solid state, which cannot be explained well by thermodynamic theories based on equilibrium or nucleation. An endeavor to find the superheating limit and mechanisms of melting and superheating becomes more complicated when various physical phenomena are involved at the similar scales. The main goal of this research is to establish a multiphysics model and to reveal the mechanism of melting and kinetic superheating of a metal nanostructure at high heating rates. The model includes elastodynamics, a fast heating of metal considering a delayed heat transfer between electron gas and lattice phonon and couplings among physical phenomena, and phase transformation incorporated with thermal fluctuation. The model successfully reproduces two independent experiments and several novel nanoscale physical phenomena are discovered. For example, the depression of the melting temperature of Al nanolayer under plane stress condition, the threshold heating rate, 1011 K/s, for kinetic superheating, a large temperature drop in a 5 nm collision region of the two solid-melt interfaces, and a strong effect of geometry on kinetic superheating in Al core-shell nanostructure at high heating rate.

Ultrafast amorphization in Ge(10)Sb(2)Te(13) thin film induced by single femtosecond laser pulse.

PubMed

Konishi, Mitsutaka; Santo, Hisashi; Hongo, Yuki; Tajima, Kazuyuki; Hosoi, Masaharu; Saiki, Toshiharu

2010-06-20

We demonstrate amorphization in a Ge(10)Sb(2)Te(13) (GST) thin film through a nonthermal process by femtosecond electronic excitation. Amorphous recording marks were formed by irradiation with a single femtosecond pulse, and were confirmed to be recrystallized by laser thermal annealing. Scanning electron microscope observations revealed that amorphization occurred below the melting temperature. We performed femtosecond pump-probe measurements to investigate the amorphization dynamics of a GST thin film. We found that the reflectivity dropped abruptly within 500fs after excitation by a single pulse and that a small change in the reflectivity occurred within 5ps of this drop.

A benchmark initiative on mantle convection with melting and melt segregation

NASA Astrophysics Data System (ADS)

Schmeling, Harro; Dannberg, Juliane; Dohmen, Janik; Kalousova, Klara; Maurice, Maxim; Noack, Lena; Plesa, Ana; Soucek, Ondrej; Spiegelman, Marc; Thieulot, Cedric; Tosi, Nicola; Wallner, Herbert

2016-04-01

In recent years a number of mantle convection models have been developed which include partial melting within the asthenosphere, estimation of melt volumes, as well as melt extraction with and without redistribution at the surface or within the lithosphere. All these approaches use various simplifying modelling assumptions whose effects on the dynamics of convection including the feedback on melting have not been explored in sufficient detail. To better assess the significance of such assumptions and to provide test cases for the modelling community we carry out a benchmark comparison. The reference model is taken from the mantle convection benchmark, cases 1a to 1c (Blankenbach et al., 1989), assuming a square box with free slip boundary conditions, the Boussinesq approximation, constant viscosity and Rayleigh numbers of 104 to 10^6. Melting is modelled using a simplified binary solid solution with linearly depth dependent solidus and liquidus temperatures, as well as a solidus temperature depending linearly on depletion. Starting from a plume free initial temperature condition (to avoid melting at the onset time) five cases are investigated: Case 1 includes melting, but without thermal or dynamic feedback on the convection flow. This case provides a total melt generation rate (qm) in a steady state. Case 2 is identical to case 1 except that latent heat is switched on. Case 3 includes batch melting, melt buoyancy (melt Rayleigh number Rm) and depletion buoyancy, but no melt percolation. Output quantities are the Nusselt number (Nu), root mean square velocity (vrms), the maximum and the total melt volume and qm approaching a statistical steady state. Case 4 includes two-phase flow, i.e. melt percolation, assuming a constant shear and bulk viscosity of the matrix and various melt retention numbers (Rt). These cases are carried out using the Compaction Boussinseq Approximation (Schmeling, 2000) or the full compaction formulation. For cases 1 - 3 very good agreement is achieved among the various participating codes. For case 4 melting/freezing formulations require some attention to avoid sub-solidus melt fractions. A case 5 is planned where all melt will be extracted and, reinserted in a shallow region above the melted plume. The motivation of this presentation is to summarize first experiences and to finalize the case definitions. References: Blankenbach, B., Busse, F., Christensen, U., Cserepes, L. Gunkel, D., Hansen, U., Harder, H. Jarvis, G., Koch, M., Marquart, G., Moore D., Olson, P., and Schmeling, H., 1989: A benchmark comparison for mantle convection codes, J. Geophys., 98, 23-38. Schmeling, H., 2000: Partial melting and melt segregation in a convecting mantle. In: Physics and Chemistry of Partially Molten Rocks, eds. N. Bagdassarov, D. Laporte, and A.B. Thompson, Kluwer Academic Publ., Dordrecht, pp. 141 - 178.

Parachute Compartment Drop Test Vehicle for Testing the Crew Exploration Vehicle's Parachute Assembly System

NASA Technical Reports Server (NTRS)

Lubey, Daniel P.; Thiele, Sara R.; Gruseck, Madelyn L.; Evans, Carol T.

2010-01-01

Though getting astronauts safely into orbit and beyond has long been one of NASA?s chief goals, their safe return has always been equally as important. The Crew Exploration Vehicle?s (CEV) Parachute Assembly System (CPAS) is designed to safely return astronauts to Earth on the next-generation manned spacecraft Orion. As one means for validating this system?s requirements and testing its functionality, a test article known as the Parachute Compartment Drop Test Vehicle (PC-DTV) will carry a fully-loaded yet truncated CPAS Parachute Compartment (PC) in a series of drop tests. Two aerodynamic profiles for the PC-DTV currently exist, though both share the same interior structure, and both have an Orion-representative weight of 20,800 lbf. Two extraction methods have been developed as well. The first (Cradle Monorail System 2 - CMS2) uses a sliding rail technique to release the PC-DTV midair, and the second (Modified DTV Sled; MDS) features a much less constrained separation method though slightly more complex. The decision as to which aerodynamic profile and extraction method to use is still not finalized. Additional CFD and stress analysis must be undertaken in order to determine the more desirable options, though at present the "boat tail" profile and the CMS2 extraction method seem to be the favored options in their respective categories. Fabrication of the PC-DTV and the selected extraction sled is set to begin in early October 2010 with an anticipated first drop test in mid-March 2011.

Extracting fields snow coverage information with HJ-1A/B satellites data

NASA Astrophysics Data System (ADS)

Dong, Wenquan; Meng, Jihua

2015-10-01

The distribution and change of snow coverage are sensitive factors of climate change. In northeast part of China, farmlands are still covered with snow in spring. Since sowing activity can only be done when the snow melted, fields snow coverage monitoring provides reference for the determination of sowing date. Because of the restriction of the sensors and application requirements, current researches on remote sensing of snow focus more on the study of musicale and large scale, rather than the study of small scale, and especially research on snow melting period is rarely reported.HJ-1A/B satellites are parts of little satellite constellation, focusing on environment and disaster monitoring and meteorological forecast. Compared to other data sources, HJ-1A/B satellites both have comparatively higher temporal and spatial resolution and are more conducive to monitor the variations of melting snow coverage at small watershed. This paper was based on HJ-1A/1B data, taking Hongxing farm of Bei'an, Heilongjiang Province, China as the study area. In this paper, we exploited the methods for extraction of snow cover information on farmland in two cases, both HJ-1A/1B CCD with HJ-1B IRS data and just HJ-1A/1B CCD data. The reason we chose the two cases is that, the two optical satellites HJ-1A/B are capable of providing a whole territory coverage period in visible light spectrum in two days, infrared spectrum in four days. So sometimes we can only obtain CCD image. In this case, the method of normalized snow index cannot be used to extract snow coverage information. Using HJ-1A/1B CCD with HJ-1B IRS data, combined with the theory of snow remote sensing monitoring, this paper analyzed spectral response characteristics of HJ-1A/1B satellites data, then the widely used Normalized Difference Snow Index(NDSI) and S3 Index were quoted to the HJ-1A/1B satellites data. The NDSI uses reflectance values of Red and SWIR spectral bands of HJ-1B, and S3 index uses reflectance values of NIR, Red and SWIR spectral bands. With multi-temporal HJ satellite data, the optimal threshold of normalized snow index was determined to divide the farmland into snow covering area, melting snow area and non-snow area. The results are quite similar to each other and of high accuracy, and the melting snow coverage can be well extracted by two types of normalized snow index. When we can only obtain CCD image, we use supervised classification method to extract melting snow coverage. With this method, the accuracy of fields snow coverage extraction is slightly lower than that using normalized snow index methods mentioned above. And in mountain area, the snow coverage area is slightly larger than that is extracted by normalized snow index methods, because the shadows make the color of snow in the valley darker, the supervised classification method divides it into non-snow coverage area, while the normalized snow index method well weakened the effect of shadow. This study shows that extraction accuracy in both cases is assessed, and both of them can meet the needs of practical applications. HJ-1A/1B satellites are conducive to monitor the variations of melting snow coverage over farmland, and they can provide reference for the determination of sowing date.

From Mush to Eruption in 1000 Years: Rapid Assembly of the Super-Sized Oruanui Magma Body

NASA Astrophysics Data System (ADS)

Allan, A. S.; Morgan, D. J.; Wilson, C. J.; Millet, M.

2012-12-01

The mush model is useful in explaining how large volumes of evolved silicic melt can be generated in and extracted from a crystal-rich source to form crystal-poor rhyolite magma bodies at shallow crustal levels. It is unclear, however, how processes of melt extraction and/or formation of the melt-dominant magma body might be reflected in the crystal record, and what physical and temporal constraints can be applied. Textural observations and in situ geochemical fingerprints in crystals from pumices of the ~25.4 ka Oruanui eruption (Taupo, New Zealand), offer new perspectives on the processes, physical conditions and timing of the melt extraction and accumulation. Almost all orthopyroxene (opx) and plagioclase (plag) cores have textures showing a period of disequilibrium (partial dissolution and/or resorption) followed by stable conditions (infilling of raddled cores; euhedral rim overgrowths). Trace element contents in amphibole (amph), which was stable and actively crystallizing in all but the most evolved parcels of Oruanui magma, complement textural evidence showing that Mn and Zn liberated by opx dissolution were preferentially sequestered in amph. Concentrations of these opx-loving elements show a prominent inflection when plotted against indices of melt evolution (e.g. Eu/Eu* in amph) marking a return to opx stability and subsequent crystallization. Plagioclase, the most abundant crystal phase, records a more complex history with significant inheritance, but textural and chemical evidence suggests that at least some of Oruanui plag crystals experienced the same departure from and return to stability as the opx. Amphibole trace element data are linked to in situ estimates of P-T-fO2 and melt H2O determined via the Ridolfi et al. (2010: Contrib Mineral Petrol 160, 45) thermobarometer. Textural and geochemical evidence combined with P-T-H2O model values indicate that three major Oruanui crystal phases (opx, amph, plag) record a significant decompression event (from ~250 to ~150 MPa) with associated cooling (from ~900 to 820°C) coupled with the destabilization of opx. We interpret this event to reflect the extraction of rhyolitic melt plus crystals from a mush-like reservoir to form the Oruanui melt-dominant body. This body grew within model pressures of 90-150 MPa (~4-6 km depth) held at 760-800°C, with a generally homogeneous melt composition, as reflected in the consistent rim compositions of the three mineral phases. Fe-Mg diffusion modelling of core-rim boundaries in opx implies that accumulation of the ~530 km3 melt dominant body began only ca. 1000 years before eruption. The traditionally envisaged quasi-static drivers of the mush model (crystal settling, gas sparging, etc.) are difficult to reconcile with the rapidity of this timeframe, and a more dynamic, external influence (e.g. from extensional tectonics) is implied.

Observed source parameters for dynamic rupture with non-uniform initial stressand relatively high fracture energy

USGS Publications Warehouse

Beeler, Nicholas M.; Kilgore, Brian D.; McGarr, Arthur F.; Fletcher, Jon Peter B.; Evans, John R.; Steven R. Baker,

2012-01-01

We have conducted dynamic rupture propagation experiments to establish the relations between in-source stress drop, fracture energy and the resulting particle velocity during slip of an unconfined 2 m long laboratory fault at normal stresses between 4 and 8 MPa. To produce high fracture energy in the source we use a rough fault that has a large slip weakening distance. An artifact of the high fracture energy is that the nucleation zone is large such that precursory slip reduces fault strength over a large fraction of the total fault length prior to dynamic rupture, making the initial stress non-uniform. Shear stress, particle velocity, fault slip and acceleration were recorded coseismically at multiple locations along strike and at small fault-normal distances. Stress drop increases weakly with normal stress. Average slip rate depends linearly on the fault strength loss and on static stress drop, both with a nonzero intercept. A minimum fracture energy of 1.8 J/m2 and a linear slip weakening distance of 33 μm are inferred from the intercept. The large slip weakening distance also affects the average slip rate which is reduced by in-source energy dissipation from on-fault fracture energy.Because of the low normal stress and small per event slip (∼86 μm), no thermal weakening such as melting or pore fluid pressurization occurs in these experiments. Despite the relatively high fracture energy, and the very low heat production, energy partitioning during these laboratory earthquakes is very similar to typical earthquake source properties. The product of fracture energy and fault area is larger than the radiated energy. Seismic efficiency is low at ∼2%. The ratio of apparent stress to static stress drop is ∼27%, consistent with measured overshoot. The fracture efficiency is ∼33%. The static and dynamic stress drops when extrapolated to crustal stresses are 2–7.3 MPa and in the range of typical earthquake stress drops. As the relatively high fracture energy reduces the slip velocities in these experiments, the extrapolated average particle velocities for crustal stresses are 0.18–0.6 m/s. That these experiments are consistent with typical earthquake source properties suggests, albeit indirectly, that thermal weakening mechanisms such as thermal pressurization and melting which lead to near complete stress drops, dominate earthquake source properties only for exceptional events unless crustal stresses are low.

Soft Listeria: actin-based propulsion of liquid drops.

PubMed

Boukellal, Hakim; Campás, Otger; Joanny, Jean-François; Prost, Jacques; Sykes, Cécile

2004-06-01

We study the motion of oil drops propelled by actin polymerization in cell extracts. Drops deform and acquire a pearlike shape under the action of the elastic stresses exerted by the actin comet, a tail of cross-linked actin filaments. We solve this free boundary problem and calculate the drop shape taking into account the elasticity of the actin gel and the variation of the polymerization velocity with normal stress. The pressure balance on the liquid drop imposes a zero propulsive force if gradients in surface tension or internal pressure are not taken into account. Quantitative parameters of actin polymerization are obtained by fitting theory to experiment.

Experimental Phase Relations of Hydrous, Primitive Melts: Implications for variably depleted mantle melting in arcs and the generation of primitive high-SiO2 melts

NASA Astrophysics Data System (ADS)

Weaver, S.; Wallace, P. J.; Johnston, A.

2010-12-01

There has been considerable experimental and theoretical work on how the introduction of H2O-rich fluids into the mantle wedge affects partial melting in arcs and chemical evolution of mantle melts as they migrate through the mantle. Studies aimed at describing these processes have become largely quantitative, with an emphasis on creating models that suitably predict the production and evolution of melts and describe the thermal state of arcs worldwide. A complete experimental data set that explores the P-T conditions of melt generation and subsequent melt extraction is crucial to the development, calibration, and testing of these models. This work adds to that data set by constraining the P-T-H2O conditions of primary melt extraction from two end-member subduction zones, a continental arc (Mexico) and an intraoceanic arc (Aleutians). We present our data in context with primitive melts found worldwide and with other experimental studies of melts produced from fertile and variably depleted mantle sources. Additionally, we compare our experimental results to melt compositions predicted by empirical and thermodynamic models. We used a piston-cylinder apparatus and employed an inverse approach in our experiments, constraining the permissible mantle residues with which our melts could be in equilibrium. We confirmed our inverse approach with forced saturation experiments at the P-T-H2O conditions of melt-mantle equilibration. Our experimental results show that a primitive, basaltic andesite melt (JR-28) from monogenetic cinder cone Volcan Jorullo (Central Mexico) last equilibrated with a harzburgite mantle residue at 1.2-1.4 GPa and 1150-1175°C with H2O contents in the range of 5.5-7 wt% H2O prior to ascent and eruption. Phase relations of a tholeiitic high-MgO basaltic melt (ID-16) from the Central Aleutians (Okmok) show the conditions of last equilibration with a fertile lherzolite mantle residue at shallower (1.2 GPa) but hotter (1275°C) conditions with approximately 2 wt% H2O. Given the estimated crustal thicknesses of these two regions, our data suggest that both samples equilibrate with mantle minerals just below the Moho. Recent viscosity dependent thermal models that account for slab geometry suggest that JR-28 melts last equilibrate with harzburgite in a cooler region of the mantle wedge. In contrast, ID-16 equilibrated with a fertile source near the hotter core of the mantle wedge. Our results support the hypothesis that lherzolite melting (wet or dry) produces essentially basaltic melts, whereas more Si-rich primitive melts require shallow hydrous melting of harzburgite or reequilibration of basaltic melts with harzburgite in the uppermost part of the wedge.

Mathematical estimation of melt depth in conduction mode of laser spot remelting process

NASA Astrophysics Data System (ADS)

Hadi, Iraj

2012-12-01

A one-dimensional mathematical model based on the front tracking method was developed to predict the melt depth as a function of internal and external parameters of laser spot remelting process in conduction mode. Power density, pulse duration, and thermophysical properties of material including thermal diffusivity, melting point, latent heat, and absorption coefficient have been taken into account in the model of this article. By comparing the theoretical results and experimental welding data of commercial pure nickel and titanium plates, the validity of the developed model was examined. Comparison shows a reasonably good agreement between the theory and experiment. For the sake of simplicity, a graphical technique was presented to obtain the melt depth of various materials at any arbitrary amount of power density and pulse duration. In the graphical technique, two dimensionless constants including the Stefan number (Ste) and an introduced constant named laser power factor (LPF) are used. Indeed, all of the internal and external parameters have been gathered in LPF. The effect of power density and pulse duration on the variation of melt depth for different materials such as aluminum, copper, and stainless steel were investigated. Additionally, appropriate expressions were extracted to describe the minimum power density and time to reach melting point in terms of process parameters. A simple expression is also extracted to estimate the thickness of mushy zone for alloys.

Microscale models of partially molten rocks and their macroscale physical properties

NASA Astrophysics Data System (ADS)

Rudge, J. F.

2017-12-01

Any geodynamical model of melt transport in the Earth's mantle requires constitutive laws for the rheology of partially molten rock. These constitutive laws are poorly known, and one way to make progress in our understanding is through the upscaling of microscale models which describe physics at the scale of individual mineral grains. Crucially, many upscaled physical properties (such as permeability) depend not only on how much melt is present, but on how that melt is arranged at the microscale; i.e. on the geometry of the melt network. Here I will present some new calculations of equilibrium melt network geometries around idealised tetrakaidecahedral grains. In contrast to several previous calculations of textural equilibrium, these calculations allow for a both a liquid-phase and a solid-phase topology that can tile 3D space. The calculations are based on a simple minimisation of surface energy using the finite element method. In these simple models just two parameters control the topology of the melt network: the porosity (volume fraction of melt), and the dihedral angle. The consquences of these melt geometries for upscaled properties such as permeability; electrical conductivity; and importantly, effective viscosity will be explored. Recent theoretical work [1,2] has suggested that in diffusion creep a small amount of melt may dramatically reduce the effective shear viscosity of a partially molten rock, with profound consequences for the nature of the asthenosphere. This contribution will show that this reduction in viscosity may have been significantly overestimated, so that the drop in the effective viscosity at onset of melting is more modest. [1] Takei, Y., and B. K. Holtzman (2009), Viscous constitutive relations of solid-liquid composites in terms of grain boundary contiguity: 1. Grain boundary diffusion control model, J. Geophys. Res., 114, B06205.[2] Holtzmann B. K. (2016) Questions on the existence, persistence, and mechanical effects of a very small melt fraction in the asthenosphere, Geophys. Geochem. Geosyst. 17, 470-484.

An observational and thermodynamic investigation of carbonate partial melting

NASA Astrophysics Data System (ADS)

Floess, David; Baumgartner, Lukas P.; Vonlanthen, Pierre

2015-01-01

Melting experiments available in the literature show that carbonates and pelites melt at similar conditions in the crust. While partial melting of pelitic rocks is common and well-documented, reports of partial melting in carbonates are rare and ambiguous, mainly because of intensive recrystallization and the resulting lack of criteria for unequivocal identification of melting. Here we present microstructural, textural, and geochemical evidence for partial melting of calcareous dolomite marbles in the contact aureole of the Tertiary Adamello Batholith. Petrographic observations and X-ray micro-computed tomography (X-ray μCT) show that calcite crystallized either in cm- to dm-scale melt pockets, or as an interstitial phase forming an interconnected network between dolomite grains. Calcite-dolomite thermometry yields a temperature of at least 670 °C, which is well above the minimum melting temperature of ∼600 °C reported for the CaO-MgO-CO2-H2O system. Rare-earth element (REE) partition coefficients (KDcc/do) range between 9-35 for adjacent calcite-dolomite pairs. These KD values are 3-10 times higher than equilibrium values between dolomite and calcite reported in the literature. They suggest partitioning of incompatible elements into a melt phase. The δ18O and δ13C isotopic values of calcite and dolomite support this interpretation. Crystallographic orientations measured by electron backscattered diffraction (EBSD) show a clustering of c-axes for dolomite and interstitial calcite normal to the foliation plane, a typical feature for compressional deformation, whereas calcite crystallized in pockets shows a strong clustering of c-axes parallel to the pocket walls, suggesting that it crystallized after deformation had stopped. All this together suggests the formation of partial melts in these carbonates. A Schreinemaker analysis of the experimental data for a CO2-H2O fluid-saturated system indeed predicts formation of calcite-rich melt between 650-880 °C, in agreement with our observations of partial melting. The presence of partial melts in crustal carbonates has important physical and chemical implications, including a drastic drop in rock viscosity and significant change in the dynamics and distribution of fluids within both the contact aureole and the intrusive body.

On the melting temperature measurements of metals under shock compression by pyrometry

NASA Astrophysics Data System (ADS)

Dai, Chengda; Hu, Jianbo; Tan, Hua

2009-06-01

The high-pressure melting temperatures are of interest in validating equation of state and modeling constitutive equation. The determination of melting temperatures for metals at megabars by pyrometry experiments is principally associated with the one-dimensional models for heat flow through dissimilar media: Grover-Urtiew model (J. App. Phys. 1974, 45: 146-152) and Tan-Ahrens model (High Press. Res. 1990, 2: 159-182). In the present work, we analyzed the insufficiency of Grover-Urtiew model in determining melting temperatures from observed interface temperatures. Based on the Tan-Ahrens model, we extracted the upper and lower bound on melting temperature at interface pressure, and proposed that the median of the both bounds was a good approximation to the melting temperatures at interface pressure. Pyrometry experiments were performed on tantalum, and the high-pressure melting temperatures were evaluated by application of the proposed approximation. The obtained results were compared with available theoretical calculations.

Simple, robust storage of drops and fluids in a microfluidic device.

PubMed

Boukellal, Hakim; Selimović, Seila; Jia, Yanwei; Cristobal, Galder; Fraden, Seth

2009-01-21

We describe a single microfluidic device and two methods for the passive storage of aqueous drops in a continuous stream of oil without any external control but hydrodynamic flow. Advantages of this device are that it is simple to manufacture, robust under operation, and drops never come into contact with each other, making it unnecessary to stabilize drops against coalescence. In one method the device can be used to store drops that are created upstream from the storage zone. In the second method the same device can be used to simultaneously create and store drops from a single large continuous fluid stream without resorting to the usual flow focusing or T-junction drop generation processes. Additionally, this device stores all the fluid introduced, including the first amount, with zero waste. Transport of drops in this device depends, however, on whether or not the aqueous drops wet the device walls. Analysis of drop transport in these two cases is presented. Finally, a method for extraction of the drops from the device is also presented, which works best when drops do not wet the walls of the chip.

Melting curve of compressed barium carbonate from in situ ionic conductivity measurements: Implications for the melting behavior of alkaline earth carbonates in Earth's deep carbon cycle

NASA Astrophysics Data System (ADS)

Dong, J.; Li, J.; Zhu, F.; Li, Z.; Farawi, R.

2017-12-01

The whereabouts of subducted carbonates place a major constraint on the Earth's deep carbon cycle, but the fraction of carbon retained in the slab and transported into the deep mantle, compared to that released from the slab and recycled to the surface, is still under debate. Knowledge of the stability of carbonated mantle rocks is pivotal for assessing the ability of slabs to carry carbonates into the deep mantle. Determination and systematic comparison of the melting curves of alkali and alkaline earth carbonates at high pressure can help construct thermodynamic models to predict the melting behavior of complex carbonated mantle rocks. Among alkaline earth carbonates, the melting behavior of barium carbonate (BaCO3) has not been adequately understood. The reported melting point of BaCO3at 1 bar differ by nearly 800 °C and constraints on the melting curve of BaCO3 at high pressure are not available. In this study, the melting temperatures of BaCO3 were determined up to 11 GPa from in situ ionic conductivity measurements using the multi-anvil apparatus at the University of Michigan. The solid-liquid boundary at high pressure was detected on the basis of a steep rise in conductivity through the sample upon melting. The melting point of BaCO3 was found to drop from 1797 °C at 3.3 GPa to 1600 °C at 5.5 GPa and then rise with pressure to 2180 °C at 11 GPa. The observed melting depression point at 5.5 GPa corresponds to the phase transition of BaCO3 from the aragonite structure (Pmcn) to post-aragonite structure (Pmmn) at 6.3 GPa, 877 °C and 8.0 GPa, 727 °C, determined from synchrotron X-ray diffraction measurements using laser-heated DAC experiments at the Advanced Photon Source, Argonne National Laboratory. These results are also compared with ex situ falling marker experiments, and the three methods together place tight constraints on the melting curve of BaCO3 and elucidates the effect of structural phase transitions on its melting behavior.

Soxhlet Extraction of Caffeine from Beverage Plants

NASA Astrophysics Data System (ADS)

Adam, D. J.; Mainwaring, J.; Quigley, Michael N.

1996-12-01

A simple procedure is described for the extraction of caffeine from coffee beans or granules, tea leaves, mat leaves, etc. Since dichloromethane and several other hazardous substances are used, the procedure is best performed in a fume hood. Following extraction, melting point determination of the crystalline precipitate establishes its positive identity. Includes 33 references.

Reduction-melting combined with a Na₂CO₃ flux recycling process for lead recovery from cathode ray tube funnel glass.

PubMed

Okada, Takashi; Yonezawa, Susumu

2014-08-01

With large quantity of flux (Na2CO3), lead can be recovered from the funnel glass of waste cathode-ray tubes via reduction-melting at 1000°C. To reduce flux cost, a technique to recover added flux from the generated oxide phase is also important in order to recycle the flux recovered from the reduction-melting process. In this study, the phase separation of sodium and the crystallization of water-soluble sodium silicates were induced after the reduction-melting process to enhance the leachability of sodium in the oxide phase and to extract the sodium from the phase for the recovery of Na2CO3 as flux. A reductive atmosphere promoted the phase separation and crystallization, and the leachability of sodium from the oxide phase was enhanced. The optimum temperature and treatment time for increasing the leachability were 700°C and 2h, respectively. After treatment, more than 90% of the sodium in the oxide phase was extracted in water. NaHCO3 can be recovered by carbonization of the solution containing sodium ions using carbon dioxide gas, decomposed to Na2CO3 at 50°C and recycled for use in the reduction-melting process. Copyright © 2014 Elsevier Ltd. All rights reserved.

Modification of drug release from acetaminophen granules by melt granulation technique - consideration of release kinetics.

PubMed

Uhumwangho, M U; Okor, R S

2006-01-01

Acetaminophen granules have been formed by a melt granulation process with the objective of retarding drug release for prolonged action formulations. The waxes used were goat wax, carnuba wax and glyceryl monostearate. In the melt granulation procedure, acetaminophen powder was triturated with the melted waxes and passed through a sieve of mesh 10 (aperture size 710 microm). The content of wax in resulting granules ranged from 10 to 40%w/w. Acetaminophen granules were also formed by the convectional method of wet granulation with starch mucilage (20%w/w). The granules were subjected to in-vitro drug release tests. The release data were subjected to analysis by three different well-established mathematical models (release kinetics) namely, - zero order flux, first order, and the Higuchi square root of time relationship. The convectional granules exhibited an initial zero order flux (first 55%) followed by a first order release profile (the remaining 45%). The pattern of drug release from the melt granulations was consistent with the first order kinetic and the Higuchi square root of time relationship, indicating a diffusion-controlled release mechanism. The first order release rate constant of the convectional granules was 1.95 +/- 0.02 h(-1). After melt granulation (wax content, 20%w/w) the rate constants dropped drastically to 0.130+/-0.001 h(-1) (goat wax), 0.120+/-0.003 h(-1) (carnuba wax), and 0.130+/-0.002 h(-1) (glyceryl monosterate) indicating that all three waxes were equivalent in retarding drug release from the melt granulations.

Thermodynamic property determination in low gravity

NASA Technical Reports Server (NTRS)

Margrave, J. L.

1977-01-01

Techniques for determining heat capacities and other properties of molten metals were investigated and critically evaluated. Precisely determining heat capacities calorimetrically in space poses several problems. The weight of a drop calorimeter block along with the necessity of obtaining a large number of data points tend to make traditional approaches appear infeasible. However, for many substances exhibiting sufficiently high thermal conductivities and with known emissivities, it appears possible to investigate their properties by observing the rate of cooling of a levitated sphere which is initially at a uniform temperature above the melting point. A special advantage of the levitation method is that considerable supercooling is expected, making the study of the heat capacities of molten metals both above and below their melting points possible.

Heat transport in the high-pressure ice mantle of large icy moons

NASA Astrophysics Data System (ADS)

Choblet, Gael; Tobie, Gabriel; Sotin, Christophe; Kalousova, Klara; Grasset, Olivier

2017-04-01

While the existence of a buried ocean sandwiched between surface ice and high-pressure (HP) polymorphs of ice emerges as the most plausible structure for the hundreds-of-kilometers thick hydrospheres within large icy moons of the Solar System (Ganymede, Callisto, Titan), little is known about the thermal structure of the deep HP ice mantle and its dynamics, possibly involving melt production and extraction. This has major implications for the thermal history of these objects as well as on the habitability of their ocean as the HP ice mantle is presumed to limit chemical transport from the rock component to the ocean. Here, we describe 3D spherical simulations of subsolidus thermal convection tailored to the specific structure of the HP ice mantle of large icy moons. Melt production is monitored and melt transport is simplified by assuming instantaneous extraction to the ocean above. The two controlling parameters for these models are the rheology of ice VI and the heat flux from the rock core. Reasonable end-members are considered for both parameters as disagreement remains on the former (especially the pressure effect on viscosity) and as the latter is expected to vary significantly during the moon's history. We show that the heat power produced by radioactive decay within the rock core is mainly transported through the HP ice mantle by melt extraction to the ocean, with most of the melt produced directly above the rock/water interface. While the average temperature in the bulk of the HP ice mantle is always relatively cool when compared to the value at the interface with the rock core (˜ 5 K above the value at the surface of the HP ice mantle), maximum temperatures at all depths are close to the melting point, often leading to the interconnection of a melt path via hot convective plume conduits throughout the HP ice mantle. Overall, we predict long periods of time during these moons' history where water generated in contact with the rock core is transported to the above ocean.

Heat transport in the high-pressure ice mantle of large icy moons

NASA Astrophysics Data System (ADS)

Choblet, G.; Tobie, G.; Sotin, C.; Kalousová, K.; Grasset, O.

2017-03-01

While the existence of a buried ocean sandwiched between surface ice and high-pressure (HP) polymorphs of ice emerges as the most plausible structure for the hundreds-of-kilometers thick hydrospheres within large icy moons of the Solar System (Ganymede, Callisto, Titan), little is known about the thermal structure of the deep HP ice mantle and its dynamics, possibly involving melt production and extraction. This has major implications for the thermal history of these objects as well as on the habitability of their ocean as the HP ice mantle is presumed to limit chemical transport from the rock component to the ocean. Here, we describe 3D spherical simulations of subsolidus thermal convection tailored to the specific structure of the HP ice mantle of large icy moons. Melt production is monitored and melt transport is simplified by assuming instantaneous extraction to the ocean above. The two controlling parameters for these models are the rheology of ice VI and the heat flux from the rock core. Reasonable end-members are considered for both parameters as disagreement remains on the former (especially the pressure effect on viscosity) and as the latter is expected to vary significantly during the moon's history. We show that the heat power produced by radioactive decay within the rock core is mainly transported through the HP ice mantle by melt extraction to the ocean, with most of the melt produced directly above the rock/water interface. While the average temperature in the bulk of the HP ice mantle is always relatively cool when compared to the value at the interface with the rock core (∼ 5 K above the value at the surface of the HP ice mantle), maximum temperatures at all depths are close to the melting point, often leading to the interconnection of a melt path via hot convective plume conduits throughout the HP ice mantle. Overall, we predict long periods of time during these moons' history where water generated in contact with the rock core is transported to the above ocean.

A benchmark initiative on mantle convection with melting and melt segregation

NASA Astrophysics Data System (ADS)

Schmeling, Harro; Dohmen, Janik; Wallner, Herbert; Noack, Lena; Tosi, Nicola; Plesa, Ana-Catalina; Maurice, Maxime

2015-04-01

In recent years a number of mantle convection models have been developed which include partial melting within the asthenosphere, estimation of melt volumes, as well as melt extraction with and without redistribution at the surface or within the lithosphere. All these approaches use various simplifying modelling assumptions whose effects on the dynamics of convection including the feedback on melting have not been explored in sufficient detail. To better assess the significance of such assumptions and to provide test cases for the modelling community we initiate a benchmark comparison. In the initial phase of this endeavor we focus on the usefulness of the definitions of the test cases keeping the physics as sound as possible. The reference model is taken from the mantle convection benchmark, case 1b (Blanckenbach et al., 1989), assuming a square box with free slip boundary conditions, the Boussinesq approximation, constant viscosity and a Rayleigh number of 1e5. Melting is modelled assuming a simplified binary solid solution with linearly depth dependent solidus and liquidus temperatures, as well as a solidus temperature depending linearly on depletion. Starting from a plume free initial temperature condition (to avoid melting at the onset time) three cases are investigated: Case 1 includes melting, but without thermal or dynamic feedback on the convection flow. This case provides a total melt generation rate (qm) in a steady state. Case 2 includes batch melting, melt buoyancy (melt Rayleigh number Rm), depletion buoyancy and latent heat, but no melt percolation. Output quantities are the Nusselt number (Nu), root mean square velocity (vrms) and qm approaching a statistical steady state. Case 3 includes two-phase flow, i.e. melt percolation, assuming a constant shear and bulk viscosity of the matrix and various melt retention numbers (Rt). These cases should be carried out using the Compaction Boussinseq Approximation (Schmeling, 2000) or the full compaction formulation. Variations of cases 1 - 3 may be tested, particularly studying the effect of melt extraction. The motivation of this presentation is to summarize first experiences, suggest possible modifications of the case definitions and call interested modelers to join this benchmark exercise. References: Blanckenbach, B., Busse, F., Christensen, U., Cserepes, L. Gun¬kel, D., Hansen, U., Har¬der, H. Jarvis, G., Koch, M., Mar¬quart, G., Moore D., Olson, P., and Schmeling, H., 1989: A benchmark comparison for mantle convection codes, J. Geo¬phys., 98, 23 38. Schmeling, H., 2000: Partial melting and melt segregation in a convecting mantle. In: Physics and Chemistry of Partially Molten Rocks, eds. N. Bagdassarov, D. Laporte, and A.B. Thompson, Kluwer Academic Publ., Dordrecht, pp. 141 - 178.

Some physical aspects of fluid-fluxed melting

NASA Astrophysics Data System (ADS)

Patiño Douce, A.

2012-04-01

Fluid-fluxed melting is thought to play a crucial role in the origin of many terrestrial magmas. We can visualize the fundamental physics of the process as follows. An infinitesimal amount of fluid infiltrates dry rock at the temperature of its dry solidus. In order to restore equilibrium the temperature must drop, so that enthalpy is released and immediately reabsorbed as enthalpy of melting. The amount of melt produced must be such that the energy balance and thermodynamic equilibrium conditions are simultaneously satisfied. We wish to understand how an initially dry rock melts in response to progressive fluid infiltration, under both batch and fractional melting constraints. The simplest physical model for this process is a binary system in which one of the components makes up a pure solid phase and the other component a pure fluid phase, and in which a binary melt phase exists over certain temperature range. Melting point depression is calculated under the assumption of ideal mixing. The equations of energy balance and thermodynamic equilibrium are solved simultaneously for temperature and melt fraction, using an iterative procedure that allows addition of fluid in infinitesimal increments. Batch melting and fractional melting are simulated by allowing successive melt increments to remain in the system (batch) or not (fractional). Despite their simplified nature, these calculations reveal some important aspects of fluid-fluxed melting. The model confirms that, if the solubility of the fluid in the melt is sufficiently high, fluid fluxed melting is an efficient mechanism of magma generation. One might expect that the temperature of the infiltrating fluid would have a significant effect on melt productivity, but the results of the calculations show this not to be the case, because a relatively small mass of low molecular weight fluid has a strong effect on the melting point of minerals with much higher molecular weights. The calculations reveal the somewhat surprising result that fluid infiltration produces more melt during fractional melting than during batch melting. This behavior, which is opposite to that of decompression melting of a dry solid, arises because the melting point depression effect of the added fluid is greater during fractional melting than during batch melting, which results in a greater release of enthalpy and, therefore, greater melt production for fractional melting than for batch melting, for the same total amount of fluid added. The difference may be considerable. As an example, suppose that 0.1 mols of H2O infiltrate 1 mol or silicate rock. Depending on the rock composition this may corresponds to ˜ 1 wt% H2O. For a given choice of model parameters (initial temperature, heat capacity and entropy of fusion), about 28% of the rock melts during fractional melting, versus some 23 % during batch melting. Fluid fluxing is a robust process of melt generation, without which magmatism at Earth's convergent plate margins would be impossible.

Determination of the Wetting Angle of Germanium and Germanium-Silicon Melts on Different Substrate Materials

NASA Technical Reports Server (NTRS)

Kaiser, Natalie; Croell, Arne; Szofran, F. R.; Cobb. S. D.; Dold, P.; Benz, K. W.

1999-01-01

During Bridgman growth of semiconductors detachment of the crystal and the melt meniscus has occasionally been observed, mainly under microgravity (microg) conditions. An important factor for detached growth is the wetting angle of the melt with the crucible material. High contact angles are more likely to result in detachment of the growing crystal from the ampoule wall. In order to achieve detached growth of germanium (Ge) and germanium-silicon (GeSi) crystals under 1g and microg conditions, sessile drop measurements were performed to determine the most suitable ampoule material as well as temperature dependence of the surface tension for GeSi. Sapphire, fused quartz, glassy carbon, graphite, SiC, pyrolytic Boron Nitride (pBN), AIN, and diamond were used as substrates. Furthermore, different cleaning procedures and surface treatments (etching, sandblasting, etc.) of the same substrate material and their effect on the wetting behavior were studied during these experiments. pBN and AIN substrates exhibited the highest contact angles with values around 170 deg.

Contactless processing of SiGe-melts in EML under reduced gravity.

PubMed

Luo, Yuansu; Damaschke, Bernd; Schneider, Stephan; Lohöfer, Georg; Abrosimov, Nikolay; Czupalla, Matthias; Samwer, Konrad

2016-01-01

The processing of semiconductors based on electromagnetic levitation is a challenge, because this kind of materials shows a poor electrical conductivity. Here, we report the results of measurements of the thermophysical properties obtained recently from highly doped semiconductors Si 1- x Ge x under microgravity conditions in the framework of parabola flight campaigns. Due to the limited time of about 20 s of microgravity especially Ge-rich samples with low melting temperatures were investigated. The measurements were performed contactlessly by video techniques with subsequent digital image processing. Linear and volume thermal expansion coefficients were measured hereby from image data. An anomaly of volume changes near the solidus temperature is visible. Viscosity and surface tension were determined by the oscillating drop technique using optic and electronic data. It was observed that the alloying of Si into Ge increases the surface tension of the melts. The viscosity is following an Arrhenius equation and shows a crossover temperature which separates simple liquid at high temperatures from cooperative liquid at low temperatures.

Thermodynamic limitations on the resolution obtainable with metal replicas.

PubMed

Woodward, J T; Zasadzinski, J A

1996-12-01

The major factor limiting resolution of metal-shadowed surfaces for electron and scanning tunnelling microscopy is the granularity of the metal film. This granularity had been believed to result from a recrystallization of the evaporated film, and hence could be limited by use of higher melting point materials for replication, or inhibited by adding carbon or other impurities to the film. However, evaporated and sputtered films of amorphous metal alloys that do not crystallize also show a granularity that decreases with increasing alloy melting point. A simple thermodynamic analysis shows that the granularity results from a dewetting of the typically low surface energy sample by the high surface energy metal film, similar to the beading up of drops of spilled mercury. The metal granularity and the resulting resolution of the metal-coated surface is proportional to the mobility of the metal on the surface after evaporation, which is related to the difference in temperature between the melting point of the metal and the sample surface temperature.

Melting and thermal expansion in the Fe-FeO system at high pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seagle, C. T.; Heinz, D. L.; Campbell, A. J.

2015-02-26

Melting in the Fe–FeO system was investigated at pressures up to 93 GPa using synchrotron X-ray diffraction (XRD) and a laser heated diamond anvil cell (DAC). The criteria for melting were the disappearance of reflections associated with one of the end-member phases upon raising the temperature above the eutectic and the reappearance of those reflections on dropping the temperature below the eutectic. The Fe–FeO system is a simple eutectic at 50 GPa and remains eutectic to at least 93 GPa. The eutectic temperature was bound at several pressure points between 19 and 93 GPa, and in some cases the liquidusmore » temperature was also determined. The eutectic temperature rises rapidly with pressure closely following the melting curve of pure Fe. A detailed phase diagram at 50 GPa is presented; the eutectic temperature is 2500 ± 150 K and the eutectic composition is bound between 7.6 ± 1.0 and 9.5 ± 1.0 wt.% O. The coefficient of thermal expansion of FeO is a strong function of volume and decreases with pressure according to a simple power law.« less

Monitoring Antarctic ice sheet surface melting with TIMESAT algorithm

NASA Astrophysics Data System (ADS)

Ye, Y.; Cheng, X.; Li, X.; Liang, L.

2011-12-01

Antarctic ice sheet contributes significantly to the global heat budget by controlling the exchange of heat, moisture, and momentum at the surface-atmosphere interface, which directly influence the global atmospheric circulation and climate change. Ice sheet melting will cause snow humidity increase, which will accelerate the disintegration and movement of ice sheet. As a result, detecting Antarctic ice sheet melting is essential for global climate change research. In the past decades, various methods have been proposed for extracting snowmelt information from multi-channel satellite passive microwave data. Some methods are based on brightness temperature values or a composite index of them, and others are based on edge detection. TIMESAT (Time-series of Satellite sensor data) is an algorithm for extracting seasonality information from time-series of satellite sensor data. With TIMESAT long-time series brightness temperature (SSM/I 19H) is simulated by Double Logistic function. Snow is classified to wet and dry snow with generalized Gaussian model. The results were compared with those from a wavelet algorithm. On this basis, Antarctic automatic weather station data were used for ground verification. It shows that this algorithm is effective in ice sheet melting detection. The spatial distribution of melting areas(Fig.1) shows that, the majority of melting areas are located on the edge of Antarctic ice shelf region. It is affected by land cover type, surface elevation and geographic location (latitude). In addition, the Antarctic ice sheet melting varies with seasons. It is particularly acute in summer, peaking at December and January, staying low in March. In summary, from 1988 to 2008, Ross Ice Shelf and Ronnie Ice Shelf have the greatest interannual variability in amount of melting, which largely determines the overall interannual variability in Antarctica. Other regions, especially Larsen Ice Shelf and Wilkins Ice Shelf, which is in the Antarctic Peninsula region, have relative stable and consistent melt occurrence from year to year.

The Influence of Lithology on the Formation of Reaction Infiltration Instabilities in Mantle Rocks

NASA Astrophysics Data System (ADS)

Pec, M.; Holtzman, B. K.; Zimmerman, M. E.; Kohlstedt, D. L.

2017-12-01

The formation of oceanic plates requires extraction of large volumes of melt from the mantle. Several lines of evidence suggest that melt extraction is rapid and, therefore, necessitates high-permeability pathways. Such pathways may form as a result of melt-rock reactions. We report the results of a series of Darcy-type experiments designed to study the development of channels due to melt-solid reactions in mantle lithologies. We sandwiched a partially molten rock between a melt source and a porous sink and annealed it at high pressure (P = 300 MPa) and high temperatures (T = 1200° or 1250°C) with a controlled pressure gradient (∂P/∂z = 0-100 MPa/mm). To study the influence of lithology on the channel formation, we synthesized partially molten rocks of harzburgitic (40:40:20 Ol - Opx - basalt), wehrlitic (40:40:20 Ol - Cpx - basalt) and lherzolitic (65:25:10 Ol - Opx - Cpx) composition. The melt source was a disk of alkali basalt. In all experiments, irrespective of the exact mineralogy, melt - undersaturated in silica - from the source dissolved pyroxene in the partially molten rock and precipitated olivine ( Fo82), thereby forming a dunite reaction layer at the interface between the source and the partially molten rock. In samples annealed under a small pressure gradient, the reaction layer was roughly planar. However, if the velocity of melt due to porous flow exceeded 0.1 µm/s, the reaction layer locally protruded into the partially molten rock forming finger-like, melt-rich channels in rocks of wehrlitic and harzburgitic composition. The lherzolitic rocks were generally impermeable to the melt except at highest-pressure gradients where a narrow fracture developed, forming a dyke which drained the melt reservoir. Three-dimensional reconstructions using micro-CT images revealed clear differences between the dyke (a narrow, through-going planar feature) and the channels formed by reactive infiltration (multiple sinuous finger-like features). Apparently, the fraction of soluble minerals together with the melt fraction in the partially molten rock control whether dykes or reactive channels develop. Our experiments demonstrate that melt-rock reactions can lead to channelization in mantle lithologies, and the observed lithological transformations broadly agree with those observed in nature

Determination of bisphenol A in thermal printing papers treated by alkaline aqueous solution using the combination of single-drop microextraction and HPLC.

PubMed

Gao, Leihong; Zou, Jing; Liu, Haihong; Zeng, Jingbin; Wang, Yiru; Chen, Xi

2013-04-01

A method for the quantitative determination of bisphenol A in thermal printing paper was developed and validated. Bisphenol A was extracted from the paper samples using 2% NaOH solution, then the extracted analyte was enriched using single-drop microextraction followed by HPLC analysis. Several parameters relating to the single-drop microextraction efficiency including extraction solvent, extraction temperature and time, stirring rate, and pH of donor phase were studied and optimized. Spiked recovery of bisphenol A at 20 and 5 mg/g was found to be 95.8 and 108%, and the method detection limit and method quantification limit was 0.03 and 0.01 mg/g, respectively. Under the optimized conditions, the proposed method was applied to the determination of bisphenol A in seven types of thermal printing paper samples, and the concentration of bisphenol A was found in the range of 0.53-20.9 mg/g. The considerably minimum usage of organic solvents (5 μL 1-octanol) and high enrichment factor (189-197) in the sample preparation are the two highlighted advantages in comparison with previously published works. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Non-Contact Temperature Requirements (NCTM) for drop and bubble physics

NASA Technical Reports Server (NTRS)

Hmelo, Anthony B.; Wang, Taylor G.

1989-01-01

Many of the materials research experiments to be conducted in the Space Processing program require a non-contaminating method of manipulating and controlling weightless molten materials. In these experiments, the melt is positioned and formed within a container without physically contacting the container's wall. An acoustic method, which was developed by Professor Taylor G. Wang before coming to Vanderbilt University from the Jet Propulsion Laboratory, has demonstrated the capability of positioning and manipulating room temperature samples. This was accomplished in an earth-based laboratory with a zero-gravity environment of short duration. However, many important facets of high temperature containerless processing technology have not been established yet, nor can they be established from the room temperature studies, because the details of the interaction between an acoustic field an a molten sample are largely unknown. Drop dynamics, bubble dynamics, coalescence behavior of drops and bubbles, electromagnetic and acoustic levitation methods applied to molten metals, and thermal streaming are among the topics discussed.

Measurements of refractive index and size of a spherical drop from Gaussian beam scattering in the primary rainbow region

NASA Astrophysics Data System (ADS)

Yu, Haitao; Sun, Hui; Shen, Jianqi; Tropea, Cameron

2018-03-01

The primary rainbow observed when light is scattered by a spherical drop has been exploited in the past to measure drop size and relative refractive index. However, if higher spatial resolution is required in denser drop ensembles/sprays, and to avoid then multiple drops simultaneously appearing in the measurement volume, a highly focused beam is desirable, inevitably with a Gaussian intensity profile. The present study examines the primary rainbow pattern resulting when a Gaussian beam is scattered by a spherical drop and estimates the attainable accuracy when extracting size and refractive index. The scattering is computed using generalized Lorenz-Mie theory (GLMT) and Debye series decomposition of the Gaussian beam scattering. The results of these simulations show that the measurement accuracy is dependent on both the beam waist radius and the position of the drop in the beam waist.

Silkworm dropping extract ameliorate trimellitic anhydride-induced allergic contact dermatitis by regulating Th1/Th2 immune response.

PubMed

Choi, Dae Woon; Kwon, Da-Ae; Jung, Sung Keun; See, Hye-Jeong; Jung, Sun Young; Shon, Dong-Hwa; Shin, Hee Soon

2018-05-26

Allergic contact dermatitis (ACD) is an inflammatory skin disease caused by hapten-specific immune response. Silkworm droppings are known to exert beneficial effects during the treatment of inflammatory diseases. Here, we studied whether topical treatment and oral administration of silkworm dropping extract (SDE) ameliorate trimellitic anhydride (TMA)-induced ACD. In ACD mice model, SDE treatment significantly suppressed the increase in both ear thickness and serum IgE levels. Furthermore, IL-1β and TNF-α levels were reduced by SDE. In allergic responses, SDE treatment significantly attenuated the production of the Th2-associated cytokine IL-4 in both ear tissue and draining lymph nodes. However, it increased the production of the Th1-mediated cytokine IL-12. Thus, these results showed that SDE attenuated TMA-induced ACD symptoms through regulation of Th1/Th2 immune response. Taken together, we suggest that SDE treatment might be a potential agent in the prevention or therapy of Th2-mediated inflammatory skin diseases such as ACD and atopic dermatitis. ACD: allergic contact dermatitis; AD: atopic dermatitis; APC: antigen presenting cells; CCL: chemokine (C-C motif) ligand; CCR: C-C chemokine receptor; Dex: dexamethasone; ELISA: enzyme-linked immunosorbent assay; IFN: interferon; Ig: immunoglobulin; IL: interleukin; OVA: ovalbumin; PS: prednisolone; SDE: silkworm dropping extract; Th: T helper; TMA: trimellitic anhydride; TNF: tumor necrosis factor.

Compensating effect of ultrasonic waves on retarding action of nanoparticles in drops liquid-liquid extraction.

PubMed

Saien, Javad; Daneshamoz, Sana

2018-03-01

The influence of ultrasonic waves on liquid-liquid extraction of circulating drops and in the presence of magnetite nanoparticles was investigated. Experiments were conducted in a column equipped with an ultrasound transducer. The frequency and intensity of received waves, measured by the hydrophone standard method, were 35.40 kHz and 0.37 mW/cm 2 , respectively. The recommended chemical system of cumene-isobutyric acid-water was used in which mass transfer resistance lies in the aqueous phase. Nanoparticles, within concentration range of (0.0003-0.0030) wt%, were added to the aqueous continuous phase. The presence of nanoparticles and ultrasonic waves provided no sensible change in drop size (within 2.49-4.17 mm) and measured terminal velocities were close to Grace model. However, presence of nanoparticles, caused mass transfer to decrease. This undesired effect was significantly diminished by using ultrasonic waves so that mass transfer coefficient increased from (73.0-178.2) to (130.2-240.2) µm/s, providing a 55.6% average enhancement. It is presumably due to disturbing the accumulated nanoparticles around the drops. The current innovative study highlights the fact that using ultrasonic waves is an interesting way to improve liquid-liquid extraction in the presence and absence of nanoparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

Melting and dissolution of subducting crust at high pressures: the key role of white mica

NASA Astrophysics Data System (ADS)

Schmidt, Max W.; Vielzeuf, Daniel; Auzanneau, Estelle

2004-11-01

Conditions of melting in the crust are generally controlled by the availability of aqueous fluid and, in the absence of fluid, by the stability of hydroxylated minerals. To depths of 80-90 km, melting is controlled by amphibole and biotite. At greater depths, both phases are unstable in crustal compositions. Simultaneous experiments on a mid-ocean ridge basalt (MORB), a greywacke, and a pelite with excess H2O of 0.4-1.4 wt.% demonstrate that, at >100 km depth (≥3.5 GPa), all three bulk compositions are composed of garnet+clinopyroxene+phengite+coesite±kyanite±rutile, phengitic white mica being the only hydrous mineral present at near-melting temperatures. At 4 GPa, melting reactions, temperatures, and initial melt compositions are thus similar in the entire subducted crust. Fluid-saturated initial melting takes place near 850 °C and melt productivities are proportional to phengite contents. All three bulk compositions produce initially slightly peraluminous potassic Si-rich granites with K:Na molar ratios of 1.4-2.0 and containing 8-13 wt.% H2O. The relatively low Na-contents of these melts result from clinopyroxene/melt partitioning coefficients (Dcpx/melt) of 2.2-4.0 at near solidus temperatures. At higher pressures (≥6.5 GPa), we infer that classical melting does not take place. Instead, the bulk H2O-contents (1.5-2.1 wt.%) in the starting materials, although low, are apparently sufficient to dissolve phengite entirely near 1050 °C. This suggests that pressure conditions beyond the singular endpoint (or second critical point) which terminates the wet solidus as defined by Ricci in 1951 [J.E. Ricci, The phase rule and heterogeneous equilibrium, Dover Publications, Inc. New York (1951) 505 p.] were reached for all three bulk compositions. Extraction of these "supercritical" solute-rich (but Na-poor) melts, which contain about 30-40% H2O, or extraction of the potassic granite melts at lower pressure leave an anhydrous garnet+clinopyroxene±coesite±kyanite±rutile residue. Our results suggest that, except for extremely cold subduction zones, the subducting crust will lose all its potassium (and most of B, Be, Rb, and Ba, and other phengite-hosted trace elements) through leaching or melting during its descent to 300 km. The potassium-rich silica-saturated liquids will immediately react with the peridotite when entering the mantle wedge thus creating source regions for ultrapotassic magmas.

Three-Dimensional Numerical Modeling of Crustal Growth at Active Continental Margins

NASA Astrophysics Data System (ADS)

Zhu, G.; Gerya, T.; Tackley, P. J.

2011-12-01

Active margins are important sites of new continental crust formation by magmatic processes related to the subduction of oceanic plates. We investigate these phenomena using a three-dimensional coupled petrological-geochemical-thermomechanical numerical model, which combines a finite-difference flow solver with a non-diffusive marker-in-cell technique for advection (I3ELVIS code, Gerya and Yuen, PEPI,2007). The model includes mantle flow associated with the subducting plate, water release from the slab, fluid propagation that triggers partial melting at the slab surface, melt extraction and the resulting volcanic crustal growth at the surface. The model also accounts for variations in physical properties (mainly density and viscosity) of both fluids and rocks as a function of local conditions in temperature, pressure, deformation, nature of the rocks, and chemical exchanges. Our results show different patterns of crustal growth and surface topography, which are comparable to nature, during subduction at active continental margins. Often, two trench-parallel lines of magmatic activity, which reflect two maxima of melt production atop the slab, are formed on the surface. The melt extraction rate controls the patterns of new crust at different ages. Moving free water reflects the path of fluids, and the velocity of free water shows the trend of two parallel lines of magmatic activity. The formation of new crust in particular time intervals is distributed in finger-like shapes, corresponding to finger-like and ridge-like cold plumes developed atop the subducting slabs (Zhu et al., G-cubed,2009; PEPI,2011). Most of the new crust is basaltic, formed from peridotitic mantle. Granitic crust extracted from melted sediment and upper crust forms in a line closer to the trench, and its distribution reflects the finger-like cold plumes. Dacitic crust extracted from the melted lower crust forms in a line farther away from the trench, and its distribution is anticorrelated with the finger-like plumes. We demonstrate the potential applicability of our model to clustering of arc magmatism in several subduction zones, such as Baja California (Ramos-Velázquez et al., Revista Mexicana de Ciencias Geológicas,2008), North Island of New Zealand (Booden et al., J. Volcanol. Geotherm. Res., 2010), Northeast Japan (Kimura and Yoshida,Journal of Petrology, 2006); Ecuador (Schütte et al., Tectonophysics,2010) and Lesser Antilles (Labanieh et al., EPSL,2010).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Chuanfu; Kresin, Vitaly V., E-mail: kresin@usc.edu

This note describes a system for transferring a load of high purity lithium metal into a molecular or cluster beam source. A hot loading vessel is thoroughly baked out while empty and overpressured with argon. A clean Li rod is then dropped in through a long narrow tube. The thoroughly degassed interior of the vessel and the rapid melting of the inserted rod facilitate contamination-free transfer of the highly reactive liquid metal into the source oven.

Structure of metal-oxide Ti-Ta-(Ti,Ta)xOy coatings during spark alloying and induction-thermal oxidation

NASA Astrophysics Data System (ADS)

Koshuro, V.; Fomin, A.; Fomina, M.; Rodionov, I.; Brzhozovskii, B.; Martynov, V.; Zakharevich, A.; Aman, A.; Oseev, A.; Majcherek, S.; Hirsch, S.

2016-08-01

The study focuses on combined spark alloying of titanium and titanium alloy surface and porous matrix structure oxidation. The metal-oxide coatings morphology is the result of melt drop transfer, heat treatment, and oxidation. The study establishes the influence of technological regimes of alloying and oxidation on morphological heterogeneity of metal- oxide system Ti-Ta-(Ti,Ta)xOy.

The consequences of crystal relaxation on CO2 partitioning in plagioclase-hosted melt inclusions

NASA Astrophysics Data System (ADS)

Drignon, M. J.; Nielsen, R.; Moore, L.; Bodnar, R. J.; Tepley, F. J., III; Kotash, A.

2017-12-01

Melt inclusions (MI) are samples of magmas representing the early stages of the development of the system, both spatially and compositionally. However, little work has been done to test and understand whether MI in plagioclase faithfully sample and maintain a record of the magmatic history. Here, we examine the effects of post entrapment processes such as sidewall crystallization (PEC) and crystal relaxation that may occur during transport and eruption and, thus alter the composition of MI. To better understand the effects of PEC and crystal relaxation, time-series experiments were conducted on plagioclase-hosted MI from plagioclase ultraphyric basalts to evaluate the extent of crystal relaxation. Run times ranged from 30 min to 4 days. To evaluate the magnitude of the effect, we analyzed the CO2 content in the vapor bubbles using Raman spectroscopy. CO2 in the MI glass was determined by SIMS. The working assumption was that relaxation would lead to a pressure drop within the MI leading to an increase in CO2 in the vapor bubbles as CO2 moved from the melt to the bubble. In addition, a drop in pressure was expected to affect the major element composition of the MI. Our results demonstrated that Na2O, CaO and Al2O3 in the MI decreased, and SiO2 and MgO increased as a function of run time. However, the magnitude of the changes cannot be explained by plagioclase melting alone. In addition, our preliminary data show more CO2 in the vapor bubbles after the 4 day runs than after 30 min runs. Using our SIMS data, and applying the total CO2 reconstruction methodology described in Moore et al. (2015), we estimate that 61% of the total CO2 in the MI is contained within the vapor bubbles after the 4 day runs and 37 % of the CO2 is in the vapor bubbles after 30 min. We hypothesize that after 4 days the CO2 exsolved from the melt into the vapor bubble and is not re-dissolved into the melt due to crystal relaxation and the concomitant pressure decrease in the MI. This suggests that plagioclase-hosted MI hold their volatiles after long runs. The total CO2 reconstruction indicates that the MI were trapped between 3000 and 6000 bars which correspond to 9-18 km. These pressures represent the pressures of last equilibration and suggest that plagioclase megacrysts crystallized in the upper mantle, and are not related to processes within or above the magma lens.

Dropwise additive manufacturing of pharmaceutical products for amorphous and self emulsifying drug delivery systems.

PubMed

Içten, Elçin; Purohit, Hitesh S; Wallace, Chelsey; Giridhar, Arun; Taylor, Lynne S; Nagy, Zoltan K; Reklaitis, Gintaras V

2017-05-30

The improvements in healthcare systems and the advent of the precision medicine initiative have created the need to develop more innovative manufacturing methods for the delivery and production of individualized dosing and personalized treatments. In accordance with the changes observed in healthcare systems towards more innovative therapies, this paper presents dropwise additive manufacturing of pharmaceutical products (DAMPP) for small scale, distributed manufacturing of individualized dosing as an alternative to conventional manufacturing methods A dropwise additive manufacturing process for amorphous and self-emulsifying drug delivery systems is reported, which utilizes drop-on-demand printing technology for automated and controlled deposition of melt-based formulations onto inert tablets. The advantages of drop on demand technology include reproducible production of droplets with adjustable sizing and high placement accuracy, which enable production of individualized dosing even for low dose and high potency drugs. Flexible use of different formulations, such as lipid-based formulations, allows enhancement of the solubility of poorly water soluble and highly lipophilic drugs with DAMPP. Here, DAMPP is used to produce solid oral dosage forms from melts of an active pharmaceutical ingredient and a surfactant. The dosage forms are analyzed to show the amorphous nature, self-emulsifying drug delivery system characteristics and dissolution behavior of these formulations. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of water on slip weakening of cohesive rocks during earthquakes (EMRP Division Outstanding ECS Award Lecture)

NASA Astrophysics Data System (ADS)

Violay, Marie; Alejandro Acosta, Mateo; Passelegue, François; Schubnel, Alexandre

2017-04-01

Fluids play an important role in fault zone and in earthquakes generation. Experimental studies of fault frictional properties in presence of fluid can provide unique insights into this phenomenon. Here we compare rotary shear experiments and tri-axial stick slip tests performed on cohesive silicate-bearing rocks (gabbro and granite) in the presence of fluids. Surprisingly, for both type of tests, the weakening mechanism (melting of the asperities) is hindered in the presence of water. Indeed, in rotary shear experiments, at a given effective normal stress (σn-pf), the decay in friction is more gradual and longer in the presence of pore water (32% of friction drop after 20 mm of slip) than under room humidity (41% after 20 mm of slip) and vacuum conditions (60% after 20 mm of slip). During stick slip tests, at a given effective confining pressure (Pc-pf), the dynamic shear stress drops are lower ( 30%) and slip distances were shorter ( 30 to 40%) in the presence of high pressure pore water (Pc=95 MPa; Pf=25 MPa) than under room humidity conditions (Pc=70 MPa; Pf=0 MPa). Thermal modeling of the asperity contacts under load shows that the presence of fluids cools the asperities and delays the formation of melt patches, increasing weakening duration.

The Physics of Foams, Droplets and Bubbles

ERIC Educational Resources Information Center

Sarker, Dipak K.

2013-01-01

Foams or bubble dispersions are common to milkshakes, bread, champagne froth, shaving mousse, shampoo, crude oil extraction systems, upholstery packing and bubble wrap, whereas the term droplet is often synonymous with either a small drop of water or a drop of oil--a type of coarse dispersion. The latter are seen in butter and milk, household…

Predicting Drop-Out from Social Behaviour of Students

ERIC Educational Resources Information Center

Bayer, Jaroslav; Bydzovska, Hana; Geryk, Jan; Obsivac, Tomas; Popelinsky, Lubomir

2012-01-01

This paper focuses on predicting drop-outs and school failures when student data has been enriched with data derived from students social behaviour. These data describe social dependencies gathered from e-mail and discussion board conversations, among other sources. We describe an extraction of new features from both student data and behaviour…

Preliminary results of sulfide melt/silicate wetting experiments in a partially melted ordinary chondrite

NASA Technical Reports Server (NTRS)

Jurewicz, Stephen R.; Jones, John H.

1994-01-01

Recently, mechanisms for core formation in planetary bodies have received considerable attention. Most current theories emphasize the need for large degrees of silicate partial melting to facilitate the coalescence and sinking of sulfide-metal liquid blebs through a low strength semi-crystalline silicate mush. This scenario is based upon observations that sulfide-metal liquid tends to form circular blebs in partially molten meteorites during laboratory experiments. However, recent experimental work by Herpfer and Larimer indicates that some sulfide-Fe liquids have wetting angles at and slightly below 60 deg in an olivine aggregate, implying an interconnected melt structure at any melt fraction. Such melt interconnectivity provides a means for gravitational compaction and extraction of the majority of a sulfide liquid phase in small planetary bodies without invoking large degrees of silicate partial melting. Because of the important ramifications of these results, we conducted a series of experiments using H-chondrite starting material in order to evaluate sulfide-liquid/silicate wetting behavior in a more complex natural system.

Optimization of physico-chemical properties of gelatin extracted from fish skin of rainbow trout (Onchorhynchus mykiss).

PubMed

Tabarestani, H Shahiri; Maghsoudlou, Y; Motamedzadegan, A; Mahoonak, A R Sadeghi

2010-08-01

Physico-chemical properties of gelatin extracted from rainbow trout (Onchorhynchus mykiss) skin were optimized using response surface methodology (RSM). Central rotatable composite design was applied to study the combined effects of NaOH concentration (0.01-0.21 N), acetic acid concentration (0.01-0.21 N) and pre-treatment time (1-3h) on yield, molecular weight distribution, gel strength, viscosity and melting point of gelatin. Regression models were developed to predict the variables. Predict values of multiple response at optimal condition were that yield=9.36%, alpha(1)/alpha(2) chain ratio=1.76, beta chain percent=32.81, gel strength=459 g, viscosity=3.2 mPa s and melting point=20.4 degrees C. The optimal condition was obtained using 0.19 N NaOH and 0.121 N acetic acid for 3h. The results showed that the concentration of H(+) during pre-treatment had significant effect on molecular weight distribution, melting point and gel strength. The concentration of OH(-) had significant effect on viscosity and for extraction yield, pretreatment time was the critical factor. (c) 2010 Elsevier Ltd. All rights reserved.

Transient kinetics measured with force steps discriminate between double-stranded DNA elongation and melting and define the reaction energetics

PubMed Central

Bongini, Lorenzo; Melli, Luca; Lombardi, Vincenzo; Bianco, Pasquale

2014-01-01

Under a tension of ∼65 pN, double-stranded DNA undergoes an overstretching transition from its basic (B-form) conformation to a 1.7 times longer conformation whose nature is only recently starting to be understood. Here we provide a structural and thermodynamic characterization of the transition by recording the length transient following force steps imposed on the λ-phage DNA with different melting degrees and temperatures (10–25°C). The shortening transient following a 20–35 pN force drop from the overstretching force shows a sequence of fast shortenings of double-stranded extended (S-form) segments and pauses owing to reannealing of melted segments. The lengthening transients following a 2–35 pN stretch to the overstretching force show the kinetics of a two-state reaction and indicate that the whole 70% extension is a B-S transition that precedes and is independent of melting. The temperature dependence of the lengthening transient shows that the entropic contribution to the B-S transition is one-third of the entropy change of thermal melting, reinforcing the evidence for a double-stranded S-form that maintains a significant fraction of the interstrand bonds. The cooperativity of the unitary elongation (22 bp) is independent of temperature, suggesting that structural factors, such as the nucleic acid sequence, control the transition. PMID:24353317

The response of surface mass and energy balance of a continental glacier to climate variability, western Qilian Mountains, China

NASA Astrophysics Data System (ADS)

Sun, Weijun; Qin, Xiang; Wang, Yetang; Chen, Jizu; Du, Wentao; Zhang, Tong; Huai, Baojuan

2017-08-01

To understand how a continental glacier responds to climate change, it is imperative to quantify the surface energy fluxes and identify factors controlling glacier mass balance using surface energy balance (SEB) model. Light absorbing impurities (LAIs) at the glacial surface can greatly decrease surface albedo and increase glacial melt. An automatic weather station was set up and generated a unique 6-year meteorological dataset for the ablation zone of Laohugou Glacier No. 12. Based on these data, the surface energy budget was calculated and an experiment on the glacial melt process was carried out. The effect of reduced albedo on glacial melting was analyzed. Owing to continuous accumulation of LAIs, the ablation zone had been darkening since 2010. The mean value of surface albedo in melt period (June through September) dropped from 0.52 to 0.43, and the minimum of daily mean value was as small as 0.1. From the records of 2010-2015, keeping the clean ice albedo fixed in the range of 0.3-0.4, LAIs caused an increase of +7.1 to +16 W m-2 of net shortwave radiation and an removal of 1101-2663 mm water equivalent. Calculation with the SEB model showed equivalent increases in glacial melt were obtained by increasing air temperature by 1.3 and 3.2 K, respectively.

The oxidation state of the mantle and the extraction of carbon from Earth's interior.

PubMed

Stagno, Vincenzo; Ojwang, Dickson O; McCammon, Catherine A; Frost, Daniel J

2013-01-03

Determining the oxygen fugacity of Earth's silicate mantle is of prime importance because it affects the speciation and mobility of volatile elements in the interior and has controlled the character of degassing species from the Earth since the planet's formation. Oxygen fugacities recorded by garnet-bearing peridotite xenoliths from Archaean lithosphere are of particular interest, because they provide constraints on the nature of volatile-bearing metasomatic fluids and melts active in the oldest mantle samples, including those in which diamonds are found. Here we report the results of experiments to test garnet oxythermobarometry equilibria under high-pressure conditions relevant to the deepest mantle xenoliths. We present a formulation for the most successful equilibrium and use it to determine an accurate picture of the oxygen fugacity through cratonic lithosphere. The oxygen fugacity of the deepest rocks is found to be at least one order of magnitude more oxidized than previously estimated. At depths where diamonds can form, the oxygen fugacity is not compatible with the stability of either carbonate- or methane-rich liquid but is instead compatible with a metasomatic liquid poor in carbonate and dominated by either water or silicate melt. The equilibrium also indicates that the relative oxygen fugacity of garnet-bearing rocks will increase with decreasing depth during adiabatic decompression. This implies that carbon in the asthenospheric mantle will be hosted as graphite or diamond but will be oxidized to produce carbonate melt through the reduction of Fe(3+) in silicate minerals during upwelling. The depth of carbonate melt formation will depend on the ratio of Fe(3+) to total iron in the bulk rock. This 'redox melting' relationship has important implications for the onset of geophysically detectable incipient melting and for the extraction of carbon dioxide from the mantle through decompressive melting.

Optically induced melting of colloidal crystals and their recrystallization.

PubMed

Harada, Masashi; Ishii, Masahiko; Nakamura, Hiroshi

2007-04-15

Colloidal crystals melt by applying focused light of optical tweezers and recrystallize after removing it. The disturbed zone by the light grows radially from the focus point and the ordering starts from the interface with the crystal. Although the larger disturbed zone is observed for the higher power optical tweezers, a master curve is extracted by normalization of the disturbed zone. The temporal changes of the normalized disturbed zone are well described with exponential functions, indicating that the melting and recrystallization process is governed by a simple relaxation mechanism.

Automation of liquid-liquid extraction-spectrophotometry using prolonged pseudo-liquid drops and handheld CCD for speciation of Cr(VI) and Cr(III) in water samples.

PubMed

Chen, Wen; Zhong, Guanping; Zhou, Zaide; Wu, Peng; Hou, Xiandeng

2005-10-01

A simple spectrophotometric system, based on a prolonged pseudo-liquid drop device as an optical cell and a handheld charge coupled device (CCD) as a detector, was constructed for automatic liquid-liquid extraction and spectrophotometric speciation of trace Cr(VI) and Cr(III) in water samples. A tungsten halogen lamp was used as the light source, and a laboratory-constructed T-tube with two open ends was used to form the prolonged pseudo-liquid drop inside the tube. In the medium of perchloric acid solution, Cr(VI) reacted with 1,5-diphenylcarbazide (DPC); the formed complex was automatically extracted into n-pentanol, with a preconcentration ratio of about 5. The organic phase with extracted chromium complex was then pumped through the optical cell for absorbance measurement at 548 nm. Under optimal conditions, the calibration curve was linear in the range of 7.5 - 350 microg L(-1), with a correlation coefficient of 0.9993. The limit of detection (3sigma) was 7.5 microg L(-1). That Cr(III) species cannot react with DPC, but can be oxidized to Cr(VI) prior to determination, is the basis of the speciation analysis. The proposed speciation analysis was sensitive, yet simple, labor-effective, and cost-effective. It has been preliminarily applied for the speciation of Cr(VI) and Cr(III) in spiked river and tap water samples. It can also be used for other automatic liquid-liquid extraction-spectrophotometric determinations.

Usability of prostaglandin monotherapy eye droppers.

PubMed

Drew, Tom; Wolffsohn, James S

2015-09-01

To determine the force needed to extract a drop from a range of current prostaglandin monotherapy eye droppers and how this related to the comfortable and maximum pressure subjects could exert. The comfortable and maximum pressure subjects could apply to an eye dropper constructed around a set of cantilevered pressure sensors and mounted above their eye was assessed in 102 subjects (mean 51.2±18.7 years), repeated three times. A load cell amplifier, mounted on a stepper motor controlled linear slide, was constructed and calibrated to test the force required to extract the first three drops from 13 multidose or unidose latanoprost medication eye droppers. The pressure that could be exerted on a dropper comfortably (25.9±17.7 Newtons, range 1.2-87.4) could be exceeded with effort (to 64.8±27.1 Newtons, range 19.9-157.8; F=19.045, p<0.001), and did not differ between repeats (F=0.609, p=0.545). Comfortable and maximum pressures exerted were correlated (r=0.618, p<0.001), neither were influenced strongly by age (r=0.138, p=0.168; r=-0.118, p=0237, respectively), but were lower in women than in men (F=12.757, p=0.001). The force required to expel a drop differed between dropper designs (F=22.528, p<0.001), ranging from 6.4 Newtons to 23.4 Newtons. The force needed to exert successive drops increased (F=36.373, p<0.001) and storing droppers in the fridge further increased the force required (F=7.987, p=0.009). Prostaglandin monotherapy droppers for glaucoma treatment vary in their resistance to extract a drop and with some a drop could not be comfortably achieved by half the population, which may affect compliance and efficacy. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Receiver function imaging of the onset of melting, implications for volcanism beneath the Afar Rift in contrast to hotspot environments

NASA Astrophysics Data System (ADS)

Rychert, C. A.; Harmon, N.; Hammond, J. O.; Laske, G.; Kendall, J.; Ebinger, C. J.; Shearer, P. M.; Bastow, I. D.; Keir, D.; Ayele, A.; Belachew, M.; Stuart, G. W.

2012-12-01

Heating, melting, and stretching destroy continents at volcanic rifts. Mantle plumes are often invoked to thermally weaken the continental lithosphere and accommodate rifting through the influx of magma. However the relative effects of mechanical stretching vs. melt infiltration and weakening are not well quantified during the evolution of rifting. S-to-p (Sp) imaging beneath the Afar Rift and hotspot regions such as Hawaii provides additional constraints. We use data from the Ethiopia/Kenya Broadband Seismic Experiment (EKBSE), the Ethiopia Afar Geophysical Lithospheric Experiment (EAGLE), a new UK/US led deployment of 46 stations in the Afar depression and surrounding area, and the PLUME experiment. We use two methodologies to investigate structure and locate robust features: 1) binning by conversion point and then simultaneous deconvolution in the frequency domain, and 2) extended multitaper followed by migration and stacking. We image a lithosphere-asthenosphere boundary at ~75 km beneath the flank of the Afar Rift vs. its complete absence beneath the rift, where the mantle lithosphere has been totally destroyed. Instead a strong velocity increase with depth at ~75 km depth matches geodynamic model predictions for a drop in melt percentage at the onset of decompression melting. The shallow depth of the onset of melting is consistent with a mantle potential temperature = 1350 - 1400°C, i.e., typical for adiabatic decompression melting. Therefore although a plume initially destroyed the mantle lithosphere, its influence directly beneath Afar today is minimal. Volcanism continues via adiabatic decompression melting assisted by strong melt buoyancy effects. This contrasts with a similar feature at much deeper depth, ~150 km, just west of Hawaii, where a deep thermal plume is hypothesized to impinge on the lithosphere. Improved high resolution imaging of rifting, ridges, and hotspots in a variety of stages and tectonic settings will increase constraints on the forces sustaining volcanism and the factors that dictate the style of breakup beneath rifts.

Comparison of STR profiling from low template DNA extracts with and without the consensus profiling method

PubMed Central

2012-01-01

Background The consensus profiling method was introduced to overcome the exaggerated stochastic effects associated with low copy number DNA typing. However, little empirical evidence has been provided which shows that a consensus profile, derived from dividing a sample into separate aliquots and including only alleles seen at least twice, gives the most informative profile, compared to a profile obtained by amplifying the entire low template DNA extract in one reaction. Therefore, this study aimed to investigate the quality of consensus profiles compared to profiles obtained using the whole low template extract for amplification. Methods A total of 100 pg and 25 pg DNA samples were amplified with the PowerPlex® ESI 16 Kits using 30 or 34 PCR cycles. A total of 100 pg and 25 pg DNA samples were then divided into three aliquots for a 34-cycle PCR and a consensus profile derived that included alleles that appeared in at least two of the replicates. Profiles from the non-split samples were compared to the consensus profiles focusing on peak heights, allele drop out, locus drop out and allele drop in. Results Performing DNA profiling on non-split extracts produced profiles with a higher percentage of correct loci compared to the consensus profiling technique. Consensus profiling did eliminate any spurious alleles from the final profile. However, there was a notable increase in allele and locus drop out when a LTDNA sample was divided prior to amplification. Conclusions The loss of information that occurs when a sample is split for amplification indicates that consensus profiling may not be producing the most informative DNA profile for samples where the template amount is limited. PMID:22748106

Sharp Interface Tracking in Rotating Microflows of Solvent Extraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glimm, James; Almeida, Valmor de; Jiao, Xiangmin

2013-01-08

The objective of this project is to develop a specialized sharp interface tracking simulation capability for predicting interaction of micron-sized drops and bubbles in rotating flows relevant to optimized design of contactor devices used in solvent extraction processes of spent nuclear fuel reprocessing. The primary outcomes of this project include the capability to resolve drops and bubbles micro-hydrodynamics in solvent extraction contactors, determining from first principles continuum fluid mechanics how micro-drops and bubbles interact with each other and the surrounding shearing fluid for realistic flows. In the near term, this effort will play a central role in providing parameters andmore » insight into the flow dynamics of models that average over coarser scales, say at the millimeter unit length. In the longer term, it will prove to be the platform to conduct full-device, detailed simulations as parallel computing power reaches the exaflop level. The team will develop an accurate simulation tool for flows containing interacting droplets and bubbles with sharp interfaces under conditions that mimic those found in realistic contactor operations. The main objective is to create an off-line simulation capability to model drop and bubble interactions in a domain representative of the averaged length scale. The technical approach is to combine robust interface tracking software, subgrid modeling, validation quality experiments, powerful computational hardware, and a team with simulation modeling, physical modeling and technology integration experience. Simulations will then fully resolve the microflow of drops and bubbles at the microsecond time scale. This approach is computationally intensive but very accurate in treating important coupled physical phenomena in the vicinity of interfaces. The method makes it possible to resolve spatial scales smaller than the typical distance between bubbles and to model some non-equilibrium thermodynamic features such as finite critical tension in cavitating liquids« less

The effect of prior hydrothermal alteration on the melting behaviour during rhyolite formation in Yellowstone, and its importance in the generation of low-δ18O magmas

NASA Astrophysics Data System (ADS)

Troch, Juliana; Ellis, Ben S.; Harris, Chris; Ulmer, Peter; Bachmann, Olivier

2018-01-01

Constraining the contribution of crustal lithologies to silicic magmas has important implications for understanding the dynamics of these potentially highly explosive systems. Low-δ18O rhyolite lavas erupted after caldera-forming events in Yellowstone have been interpreted as the products of bulk crustal melting of previously deposited and hydrothermally altered rhyolitic material in the down-dropped caldera roof. For lack of compositional data, the "self-cannibalisation bulk melting"-theory relies on the assumption that hydrothermally altered materials are near-cotectic and hydrous (>3 wt% H2O) and will therefore readily melt at temperatures below 850 °C. In this study, we examine the drillcores Y2, Y9 and Y13 from a USGS drilling campaign in Yellowstone in order to characterise the hydrothermally altered material in terms of major and trace elements, oxygen isotopes and water contents. Rhyolite δ18O values can decrease from "normal" (+5.8 to +6.1‰) on the surface to as low as -5‰ at depths of 100-160 m and probably lower as a function of increasing temperature with depth. While material in the drillcores is variably altered and silicified, oxygen isotope exchange in these samples is not accompanied by systematic changes in major and trace element composition and is independent of uptake of water. More than 75% of the drillcore samples have <0.5 wt% H2O, making water the most limiting factor during melting. Modelled melting curves using rhyolite-MELTS suggest a maximum of 35% melt can be created at 850 °C, and that bulk melting would require extremely high temperatures >1100 °C. Therefore, large-scale bulk melting is unrealistic and low-δ18O rhyolite magmas more likely result from assimilation of <30% partially melted altered crust with low δ18O into a normal-δ18O rhyolite magma from the main reservoir. This mechanism is supported by isotopic mass-balance models as well as thermal and volumetric constraints, and may be similarly applicable to other low-δ18O settings worldwide.

Metasomatic Enrichment of Oceanic Lithospheric Mantle Documented by Petit-Spot Xenoliths

NASA Astrophysics Data System (ADS)

Pilet, S.; Abe, N.; Rochat, L.; Hirano, N.; Machida, S.; Kaczmarek, M. A.; Muntener, O.

2015-12-01

Oceanic lithosphere is generally interpreted as mantle residue after MORB extraction. It has been proposed, however, that metasomatism could take place at the interface between the low-velocity zone and the cooling and thickening oceanic lithosphere or by the percolation of low-degree melts produced in periphery of Mid Ocean Ridges. This later process is observed in slow spreading ridges and ophiolites where shallow oceanic lithospheric mantle could be metasomatized/refertilized during incomplete MORB melt extraction. Nevertheless, direct evidence for metasomatic refertilization of the deep part of the oceanic lithospheric mantle is still missing. Xenoliths and xenocrysts sampled by petit-spot volcanoes interpreted as low-degree melts extracted from the base of the lithosphere in response to plate flexure, provide important new information about the nature and the processes associated with the evolution of oceanic lithospheric mantle. Here, we report, first, the presence of a garnet xenocryst in petit-spot lavas from Japan characterized by low-Cr, low-Ti content and mostly flat MREE-HREE pattern. This garnet is interpreted as formed during subsolidus cooling of pyroxenitic or gabbroic cumulates formed at ~1 GPa during the incomplete melt extraction at the periphery of the Pacific mid-ocean ridge. It is the first time that such processes are documented in fast spreading context. Second, we report petit-spot mantle xenoliths with cpx trace element "signatures" characterized by high U, Th, relative depletion in Nb, Pb, Ti and high but variable LREE/HREE ratio suggesting equilibration depth closed to the Gt/Sp transition zone. Such "signatures" are unknown from oceanic settings and show unexpected similarity to melt-metasomatized gt-peridotites sampled by kimberlites. This similarity suggests that metasomatic processes are not restricted to continental setting, but could correspond to a global mechanism at the lithosphere-asthenosphere boundary. As plate flexure represents a global mechanism in subduction zone, a portion of oceanic lithospheric mantle is likely to be metasomatized; recycling of these enriched domains into the convecting mantle is fundamental to understand the generation of small scale mantle isotopic and volatile heterogeneities sampled by OIBs and MORBs.

In situ determination of binary alloy melt compositions in the LHDAC by X- Radiography

NASA Astrophysics Data System (ADS)

Lord, O. T.; Walter, M. J.; Walker, D.; Clark, S. M.

2008-12-01

Constraining the light element in Earth's molten outer core requires an understanding of the melting phase relations in iron-light element binary systems. For example, it is critical to determine the composition of liquids at binary eutectics. Typically such measurements are carried out after the sample has been quenched in temperature and pressure. Such 'cook and look' methods possibly suffer from systematic errors introduced by exsolution of the light element from the melt on quench and error in the reintegration of the liquid composition [1]. Here, we present a novel method for the determination of melt compositions in iron-light element binary systems in situ in the LHDAC at simultaneous high-pressure, high-temperature conditions. Samples consist of a light element bearing compound, such as FeO, surrounded by a pure iron ring, forming a donut ~100 μm in diameter and ~15 μm thick. The donuts are loaded into stainless steel gaskets in the DAC, sandwiched between discs fabricated from sol-gel deposited nanocrystalline Al2O3 with similar dimensions to the donut. Pressure is monitored by ruby fluorescence during compression. The sample is heated at the boundary between the iron and light element compound using two 100 W IR lasers in a double-sided configuration at beamline 12.2.2 at the Advanced Light Source. Temperature is measured by spectroradiometry. Before, during and after melting, X-radiographic images of the sample are taken by shining a defocused beam of synchrotron X-rays through the sample and onto a CdWO4 phosphor. The visible light from the phosphor is then focused onto a high resolution CCD, where absorption contrast images are recorded. The absorption of the molten region is then determined, and it's composition calculated by linear interpolation between the absorption of the two solid end members. As a test of the reliability of the method we measured the Fe-FeS eutectic to 20 GPa and our results are in good agreement with previous studies that are based on various ex situ techniques. We measured the eutectic composition between Fe and Fe3C up to 44 GPa, and found that the carbon content of the eutectic drops rapidly above about 10 GPa, dropping to less that 1 wt% by 44 GPa. This result is generally consistent with the thermodynamic calculations of Wood [2]. Experiments on the Fe-FeSi eutectic yielded an increase in the Si content of the eutectic to 35 GPa, consistent with data from large volume press experiments [3] Notably, melting experiments at 35-43 GPa and ~2500 K on a boundary between Fe and FeO failed to yield evidence of a melt with a composition distinguishable from pure iron. However, an experiment at 12 GPa and 2700 K between Fe and FeO(OH) did yield a melt with a composition intermediate between the two end members. This suggests that O solubility in the Fe-O eutectic melt is low at mid-mantle pressures, but that H may dissolve into the melt by itself or in combination with O. [1] Walker, D., 2005. Core-Mantle chemical issues. Canad. Min., 43, 1553-1564 [2] Wood, B. J., 1993. Carbon in the core. Earth Planet Sci. Lett., 117, 593-607 [3] Kuwayama, Y. & Hirose, K., 2004. Phase relations in the system Fe-FeSi at 21 GPa. Am. Min., 89, 273-276.

Systematics of melt stagnation in peridotites from the Godzilla Megamullion

NASA Astrophysics Data System (ADS)

Loocke, M.; Snow, J. E.; Ohara, Y.

2010-12-01

The Godzilla Megamullion (GM) Massif is the largest known example of an Oceanic Core Complex (OCC) or the exhumed footwall of a low angle-large offset oceanic detachment fault. It lies on the extinct Parece Vela Rift spreading center within the Parece Vela Back-arc Basin of the Philippine Sea. This has thus allowed for sampling of a young back-arc mantle section. Sampling of the massif has returned a dominantly ultramafic lithology, divided petrographically into depleted, fertile, and melt-percolated groups (1). Petrographic analysis of the extant peridotite thin section collection found that 44% of all GM peridotites (71 out of 161) exhibit evidence of plagioclase impregnation compared to the worldwide abyssal peridotite average of ~20% (2). The mullion is divided up into three regions, the proximal region ( closest to termination of spreading), the medial region, and the distal region (furthest from the termination of spreading)(3).Observations by region provide that 53% ( 62 out of 116 samples) in the proximal region (15 dredges), 12% ( 2 out of 17 samples) in the medial mullion (3 dredges), and 25% (7 out of 28) in the distal mullion (5 dredges) show of evidence of plagioclase impregnation (4). Major element analyses of spinels were completed using the Cameca SX-50 Electron Microprobe facility at the University of Houston. The Cr# [100 x Cr/(Cr + Al)] ranges from 10 to 65 with TiO2 concentrations ranging from less than 0.01 up to 1.6 wt%. When the Cr#s of the samples are plotted along the massif, a pattern of melt depletion exists that is consistent with the degree of plagioclase impregnation. In the distal region, Cr#s start at around an average of 35 and range up to 65 for melt percolated samples. In the medial region, a drop off in Cr# of about 1 Cr# per kilometer is observed with the trend bottoming out at around a Cr# of 10. In the proximal region, Cr#s closer to the medial region are observed as having more fertile values of around 20 but are found amongst melt-impregnated samples with values ranging up to 50. This range is seen as having increasing minimum and maximum values with distance away from the medial section until it reaches its peak at a base Cr# of 30 with a maximum of 65. From this trend, a general model for the secular evolution of the GM mantle section can be established (5). The ridge segment experienced normal mid-oceanic ridge growth with robust mantle melting during the time period represented by the distal region. At the boundary to the medial region, a steep drop-off in melt productivity was experienced, leading to minimal mantle melting during the time period represented by the medial region. Soon thereafter, melting began again, but was trapped in a thickened and cooling lithosphere, causing the melt to pool and react with its host peridotite. (1) Ohara, et al., (2003) G3. 4 (7), 8611, 10.1029/2002GC000469. (2) Dick (1989) Geol Soc. Lond. Spec. Pub. 42:71-105. (3) Ohara, et al., (2009), Eos Trans. AGU, 90(52), Fall Meet. Suppl. Abst.Num. T33D-06 (4) Loocke, et al., (2009), Eos Trans. AGU, 90(52), Fall Meet. Suppl. Abst.Num. T21A-1776 (5) Snow, et al., (2009), Eos Trans. AGU, 90(52), Fall Meet. Suppl. Abst.Num. T33D-07

Drop shape visualization and contact angle measurement on curved surfaces.

PubMed

Guilizzoni, Manfredo

2011-12-01

The shape and contact angles of drops on curved surfaces is experimentally investigated. Image processing, spline fitting and numerical integration are used to extract the drop contour in a number of cross-sections. The three-dimensional surfaces which describe the surface-air and drop-air interfaces can be visualized and a simple procedure to determine the equilibrium contact angle starting from measurements on curved surfaces is proposed. Contact angles on flat surfaces serve as a reference term and a procedure to measure them is proposed. Such procedure is not as accurate as the axisymmetric drop shape analysis algorithms, but it has the advantage of requiring only a side view of the drop-surface couple and no further information. It can therefore be used also for fluids with unknown surface tension and there is no need to measure the drop volume. Examples of application of the proposed techniques for distilled water drops on gemstones confirm that they can be useful for drop shape analysis and contact angle measurement on three-dimensional sculptured surfaces. Copyright © 2011 Elsevier Inc. All rights reserved.

Mantle Wedge formation during Subduction Initiation: evidence from the refertilized base of the Oman ophiolitic mantle

NASA Astrophysics Data System (ADS)

Prigent, C.; Guillot, S.; Agard, P.; Godard, M.; Lemarchand, D.; Ulrich, M.

2015-12-01

Although the Oman ophiolite is classically regarded as being the direct analog of oceanic lithosphere created at fast spreading ridges, the geodynamic context of its formation is still highly debated. The other alternative end-member model suggests that this ophiolite entirely formed in a supra-subduction zone setting. The latter one is supported by studies on volcanic sequences whereas studies dealing on the mantle section do not involve a significant influence of subduction processes on its structure and composition. We herein focus on basal peridotites from all along the ophiolite strike in order to decipher and characterize potential fluid/melt transfers relate to subduction processes. Samples were taken across the basal banded unit directly overlying the amphibolitic/granulitic metamorphic sole which represents an accreted part of the lower plate. We carried out a petrological, structural and geochemical study on these rocks and their constitutive minerals. Our results show that basal peridotites range from lherzolites to highly depleted harzburgites in composition. Clinopyroxenes (cpx) display melt impregnation textures and co-crystallized with HT/HP amphiboles (amph), spinels and sulfurs. Major and trace elements of the constitutive minerals indicate that these minerals represent trapped incremental partial melt after hydrous melting. Different cpx-bearing lithologies then result from varying degrees of partial melting and melt extraction. Combined with Boron isotopic data, we demonstrate that fluids responsible for hydrous melting of these ophiolitic basal peridotites are subduction-related, most likely derived from dehydration of the metamorphic sole during its formation in subduction initiation. From these observations and thermal constraints, we interpret the occurrence of these basal lherzolites as representing a freezing front developed by thermal re-equilibration (cooling) during subduction processes: subduction-related hydrous partial melts were extracted at different degrees until getting ultimately trapped, and crystallized cpx, amph and other associated minerals. If our interpretation is correct, the base of the Oman ophiolite could provide the best proxy for the composition of a frozen-in, incipiently forming mantle wedge.

Increased mantle heat flow with on-going rifting of the West Antarctic rift system inferred from characterisation of plagioclase peridotite in the shallow Antarctic mantle

NASA Astrophysics Data System (ADS)

Martin, A. P.; Cooper, A. F.; Price, R. C.

2014-03-01

The lithospheric, and shallow asthenospheric, mantle in Southern Victoria Land are known to record anomalously high heat flow but the cause remains imperfectly understood. To address this issue plagioclase peridotite xenoliths have been collected from Cenozoic alkalic igneous rocks at three localities along a 150 km transect across the western shoulder of the West Antarctic rift system in Southern Victoria Land, Antarctica. There is a geochemical, thermal and chronological progression across this section of the rift shoulder from relatively hot, young and thick lithosphere in the west to cooler, older and thinner lithosphere in the east. Overprinting this progression are relatively more recent mantle refertilising events. Melt depletion and refertilisation was relatively limited in the lithospheric mantle to the west but has been more extensive in the east. Thermometry obtained from orthopyroxene in these plagioclase peridotites indicates that those samples most recently affected by refertilising melts have attained the highest temperatures, above those predicted from idealised dynamic rift or Northern Victoria Land geotherms and higher than those prevailing in the equivalent East Antarctic mantle. Anomalously high heat flow can thus be attributed to entrapment of syn-rift melts in the lithosphere, probably since regional magmatism commenced at least 24 Myr ago. The chemistry and mineralogy of shallow plagioclase peridotite mantle can be explained by up to 8% melt extraction and a series of refertilisation events. These include: (a) up to 8% refertilisation by a N-MORB melt; (b) metasomatism involving up to 1% addition of a subduction-related component; and (c) addition of ~ 1.5% average calcio-carbonatite. A high MgO group of clinopyroxenes can be modelled by the addition of up to 1% alkalic melt. Melt extraction and refertilisation mainly occurred in the spinel stability field prior to decompression and uplift. In this region mantle plagioclase originates by a combination of subsolidus recrystallisation during decompression within the plagioclase stability field and refertilisation by basaltic melt.

Estimation of Melt Ponds over Arctic Sea Ice using MODIS Surface Reflectance Data

NASA Astrophysics Data System (ADS)

Ding, Y.; Cheng, X.; Liu, J.

2017-12-01

Melt ponds over Arctic sea ice is one of the main factors affecting variability of surface albedo, increasing absorption of solar radiation and further melting of snow and ice. In recent years, a large number of melt ponds have been observed during the melt season in Arctic. Moreover, some studies have suggested that late spring to mid summer melt ponds information promises to improve the prediction skill of seasonal Arctic sea ice minimum. In the study, we extract the melt pond fraction over Arctic sea ice since 2000 using three bands MODIS weekly surface reflectance data by considering the difference of spectral reflectance in ponds, ice and open water. The preliminary comparison shows our derived Arctic-wide melt ponds are in good agreement with that derived by the University of Hamburg, especially at the pond distribution. We analyze seasonal evolution, interannual variability and trend of the melt ponds, as well as the changes of onset and re-freezing. The melt pond fraction shows an asymmetrical growth and decay pattern. The observed melt ponds fraction is almost within 25% in early May and increases rapidly in June and July with a high fraction of more than 40% in the east of Greenland and Beaufort Sea. A significant increasing trend in the melt pond fraction is observed for the period of 2000-2017. The relationship between melt pond fraction and sea ice extent will be also discussed. Key Words: melt ponds, sea ice, Arctic

Frictional melt generated by the 2008 Mw 7.9 Wenchuan earthquake and its faulting mechanisms

NASA Astrophysics Data System (ADS)

Wang, H.; Li, H.; Si, J.; Sun, Z.; Zhang, L.; He, X.

2017-12-01

Fault-related pseudotachylytes are considered as fossil earthquakes, conveying significant information that provide improved insight into fault behaviors and their mechanical properties. The WFSD project was carried out right after the 2008 Wenchuan earthquake, detailed research was conducted in the drilling cores. 2 mm rigid black layer with fresh slickenlines was observed at 732.6 m in WFSD-1 cores drilled at the southern Yingxiu-Beichuan fault (YBF). Evidence of optical microscopy, FESEM and FIB-TEM show it's frictional melt (pseudotachylyte). In the northern part of YBF, 4 mm fresh melt was found at 1084 m with similar structures in WFSD-4S cores. The melts contain numerous microcracks. Considering that (1) the highly unstable property of the frictional melt (easily be altered or devitrified) under geological conditions; (2) the unfilled microcracks; (3) fresh slickenlines and (4) recent large earthquake in this area, we believe that 2-4 mm melt was produced by the 2008 Wenchuan earthquake. This is the first report of fresh pseudotachylyte with slickenlines in natural fault that generated by modern earthquake. Geochemical analyses show that fault rocks at 732.6 m are enriched in CaO, Fe2O3, FeO, H2O+ and LOI, whereas depleted in SiO2. XRF results show that Ca and Fe are enriched obviously in the 2.5 cm fine-grained fault rocks and Ba enriched in the slip surface. The melt has a higher magnetic susceptibility value, which may due to neoformed magnetite and metallic iron formed in fault frictional melt. Frictional melt visible in both southern and northern part of YBF reveals that frictional melt lubrication played a major role in the Wenchuan earthquake. Instead of vesicles and microlites, numerous randomly oriented microcracks in the melt, exhibiting a quenching texture. The quenching texture suggests the frictional melt was generated under rapid heat-dissipation condition, implying vigorous fluid circulation during the earthquake. We surmise that during earthquakes vigorous fluid influx within fault zone, likely dissipating the frictional heat and resulting in rapid temperature drop, may facilitate the solidification of melt and hamper the aftermost fault slip. Meanwhlie, the high temperature fluid-rock interaction may play an important role in the chemical elements migrating in fault zones.

Comparison of solidification of floating drop and homogenous liquid-liquid microextractions for the extraction of two plasticizers from the water kept in PET-bottles.

PubMed

Yamini, Yadollah; Ghambarian, Mahnaz; Khalili-Zanjani, Mohammad Reza; Faraji, Mohammad; Shariati, Shahab

2009-09-01

Two approaches based on solidification of floating drop microextraction (SFDME) and homogenous liquid-liquid microextraction (HLLE) were compared for the extraction and preconcentration of di-(2-ethylhexyl) phthalate (DEHP) and di-(2-ethylhexyl) adipate (DEHA) from the mineral water samples. In SFDME, a floated drop of the mixture of acetophenone/1-undecanol (1:8) was exposed on the surface of the aqueous solution and extraction was permitted to occur. In HLLE, a homogenous ternary solvent system was used by water/methanol/chloroform and the phase separation phenomenon occurred by salt addition. Under the optimal conditions, the LODs for the two target plasticizers (DEHA and DEHP), obtained by SFDME-GC-FID and HLLE-GC-FID, were ranged from 0.03 to 0.01 microg/L and 0.02 to 0.01 microg/L, respectively. HLLE provided higher preconcentration factors (472.5- and 551.2-fold) within the shorter extraction time as well as better RSDs (4.5-6.9%). While, in SFDME, high preconcentration factors in the range of 162-198 and good RSDs in the range of 5.2-9.6% were obtained. Both methods were applied for the analysis of two plasticizers in different water samples and two target plasticizers were found in the bottled mineral water after the expiring time and the boiling water was exposed to a polyethylene vial.

Respiratory allergy to inhaled bat guano.

PubMed

el-Ansary, E H; Tee, R D; Gordon, D J; Taylor, A J

1987-02-07

In the Sudan many asthmatic patients attribute their symptoms to inhalation of bat droppings. Design of the roofs of many Sudanese buildings allows black bats to roost; guano drops through cracks in the ceiling into the rooms below where it can be inhaled and cause allergic respiratory disorders. Seven atopic patients seen at Sennar Hospital with bat-related case-histories were investigated. Six had bronchial asthma and allergic rhinitis and one had asthma alone. Extracts of yellow hairy bat, black bat, and bat droppings were made. All seven patients had a positive skin prick test and specific IgE antibodies (RAST) to bat droppings. Three patients also had a positive RAST to both yellow and black bats and one patient to yellow bat. Droppings are probably the major allergen source in bat-related respiratory allergy.

Melt extraction and mantle source at a Southwest Indian Ridge Dragon Bone amagmatic segment on the Marion Rise

NASA Astrophysics Data System (ADS)

Gao, Changgui; Dick, Henry J. B.; Liu, Yang; Zhou, Huaiyang

2016-03-01

This paper works on the trace and major element compositions of spatially associated basalts and peridotites from the Dragon Bone amagmatic ridge segment at the eastern flank of the Marion Platform on the ultraslow spreading Southwest Indian Ridge. The rare earth element compositions of basalts do not match the pre-alteration Dragon Bone peridotite compositions, but can be modeled by about 5 to 10% non-modal batch equilibrium melting from a DMM source. The Dragon Bone peridotites are clinopyroxene-poor harzburgite with average spinel Cr# 27.7. The spinel Cr# indicates a moderate degree of melting. However, CaO and Al2O3 of the peridotites are lower than other abyssal peridotites at the same Mg# and extent of melting. This requires a pyroxene-poor initial mantle source composition compared to either hypothetical primitive upper mantle or depleted MORB mantle sources. We suggest a hydrous melting of the initial Dragon Bone mantle source, as wet melting depletes pyroxene faster than dry. According to the rare earth element patterns, the Dragon Bone peridotites are divided into two groups. Heavy REE in Group 1 are extremely fractionated from middle REE, which can be modeled by 7% fractional melting in the garnet stability field and another 12.5 to 13.5% in the spinel stability field from depleted and primitive upper mantle sources, respectively. Heavy REE in Group 2 are slightly fractionated from middle REE, which can be modeled by 15 to 20% fractional melting in the spinel stability field from a depleted mantle source. Both groups show similar melting degree to other abyssal peridotites. If all the melt extraction occurred at the middle oceanic ridge where the peridotites were dredged, a normal 6 km thick oceanic crust is expected at the Dragon Bone segment. However, the Dragon Bone peridotites are exposed in an amagmatic ridge segment where only scattered pillow basalts lie on a partially serpentinized mantle pavement. Thus their depletion requires an earlier melting occurred at other place. Considering the hydrous melting of the initial Dragon Bone mantle source, we suggest the earlier melting event occurred in an arc terrain, prior to or during the closure of the Mozambique Ocean in the Neproterozoic, and the subsequent assembly of Gondwana. Then, the Al2O3 depleted and thus buoyant peridotites became the MORB source for Southwest Indian Ridge and formed the Marion Rise during the Gondwana breakup.

Experimental determination of the partitioning of gallium between solid iron metal and synthetic basaltic melt Electron and ion microprobe study

NASA Technical Reports Server (NTRS)

Drake, M. J.; Newsom, H. E.; Reed, S. J. B.; Enright, M. C.

1984-01-01

The distribution of Ga between solid Fe metal and synthetic basaltic melt is investigated experimentally at temperatures of 1190 and 1330 C, and over a narrow range of oxygen fugacities. Metal-silicate reversal experiments were conducted, indicating a close approach to equilibrium. The analysis of the partitioned products was performed using electron and ion microprobes. At one bar total pressure, the solid metal/silicate melt partition coefficient D(Ga) is used to evaluate metal-silicate fractionation processes in the earth, moon, and Eucrite Parent Body (EPB). It is found that the depletion of Ga abundances in the EPB is due to the extraction of Ga into a metallic core. Likewise, the depletion of Ga in the lunar mantle is consistent with the extraction of Ga into a smaller lunar core if Ga was originally present in a subchondritic concentration. The relatively high Ga abundances in the earth's mantle are discussed, with reference to several theoretical models.

Detection of plant oil DNA using high resolution melting (HRM) post PCR analysis: a tool for disclosure of olive oil adulteration.

PubMed

Vietina, Michelangelo; Agrimonti, Caterina; Marmiroli, Nelson

2013-12-15

Extra virgin olive oil is frequently subjected to adulterations with addition of oils obtained from plants other than olive. DNA analysis is a fast and economic tool to identify plant components in oils. Extraction and amplification of DNA by PCR was tested in olives, in milled seeds and in oils, to investigate its use in olive oil traceability. DNA was extracted from different oils made of hazelnut, maize, sunflower, peanut, sesame, soybean, rice and pumpkin. Comparing the DNA melting profiles in reference plant materials and in the oils, it was possible to identify any plant components in oils and mixtures of oils. Real-Time PCR (RT-PCR) platform has been added of the new methodology of high resolution melting (HRM), both were used to analyse olive oils mixed with different percentage of other oils. Results showed HRM a cost effective method for efficient detection of adulterations in olive oils. Copyright © 2013 Elsevier Ltd. All rights reserved.

Detailed Segmentation and Episodic Propagation of the 2014 Bárðarbunga Dike Intrusion and Seismicity Accompanying the Sustained Holuhraun Eruption, Central Icleand

NASA Astrophysics Data System (ADS)

Ágústsdóttir, T.; Woods, J.; Greenfield, T. S.; Green, R. G.; White, R. S.; Brandsdottir, B.

2015-12-01

An intense swarm of seismicity on 16 August 2014 marked the intrusion of a large dike from the subglacial Bárðarbunga volcano, central Iceland. Melt propagated laterally from the central volcano at the brittle-ductile boundary at ~6 km b.s.l. and created over 30,000 earthquakes along a 46 km path heading NE from Bárðarbunga. On 31 August a fissure eruption began at Holuhraun and the seismicity rate within the dike dropped instantaneously to a much lower level suggesting that once a pathway to the surface had formed, magma was able to flow freely and largely aseismically. Melt was fed from the subsiding Bárðarbunga volcano to Holuhraun for 6 months, until the eruption ceased on 27 February 2015. We discuss the relationship between bursts of seismicity in the feeder volcano and periods of rapid dike propagation. We use a dense seismic network and relative earthquake relocations to map in detail the segmentation of the dike on all scales. New dike segments were initiated with a rapid advance of the dike tip at typically 1 km/h, separated by pauses of up to 78 h. During the stalled periods the magma pressure built until it was sufficient to fracture a new segment, which then propagated rapidly forward. Large segments became seismically quiet once a new segment had intruded beyond it as extensional stresses had been relieved and melt was able to flow freely. Each rapid propagation phase was accompanied by a drop in the seismicity rate directly behind the dike tip, most likely due to a stress shadow being formed behind the dike tip. Moment tensor solutions show that the dominant failure mechanism is left-lateral strike slip faulting at the leading edge, orientated parallel to the dike, with a combination of right-lateral, left-lateral and normal faulting behind the dike tip, contradicting many widely used models. Much of the seismicity behind the tip may represent fracture of frozen melt as the dike inflated and propagated forward

Grain-Size Dynamics Beneath Mid-Ocean Ridges: Implications for Permeability and Melt Extraction

NASA Astrophysics Data System (ADS)

Turner, A. J.; Katz, R. F.; Behn, M. D.

2014-12-01

The permeability structure of the sub-ridge mantle plays an important role in how melt is focused and extracted at mid-ocean ridges. Permeability is controlled by porosity and the grain size of the solid mantle matrix, which is in turn controlled by the deformation conditions. To date, models of grain size evolution and mantle deformation have not been coupled to determine the influence of spatial variations in grain-size on the permeability structure at mid-ocean ridges. Rather, current models typically assume a constant grain size for the whole domain [1]. Here, we use 2-D numerical models to evaluate the influence of grain-size variability on the permeability structure beneath a mid-ocean ridge and use these results to speculate on the consequences for melt focusing and extraction. We construct a two-dimensional, single phase model for the steady-state grain size beneath a mid-ocean ridge. The model employs a composite rheology of diffusion creep, dislocation creep, dislocation accommodated grain boundary sliding, and a brittle stress limiter. Grain size is calculated using the "wattmeter" model of Austin and Evans [2]. We investigate the sensitivity of the model to global variations in grain growth exponent, potential temperature, spreading-rate, and grain boundary sliding parameters [3,4]. Our model predicts that permeability varies by two orders of magnitude due to the spatial variability of grain size within the expected melt region of a mid-ocean ridge. The predicted permeability structure suggests grain size may promote focusing of melt towards the ridge axis. Furthermore, the calculated grain size structure should focus melt from a greater depth than models that exclude grain-size variability. Future work will involve evaluating this hypothesis by implementing grain-size dynamics within a two-phase mid-ocean ridge model. The developments of such a model will be discussed. References: [1] R. F. Katz, Journal of Petrology, volume 49, issue 12, page 2099, 2008. [2] N. J. Austin and B. Evans, Geology, 35:354, 2007. [3] G. Hirth and D. Kohlstedt, In Inside the Subduction Factory, volume 138 of AGU Geophysical Monograph, 2003. [4] L. N. Hansen et al., JGR (Solid Earth), 116:B08201, 2011.

Extracting of yellowfin tuna (Thunnus albacares) fish skin gelatin as influenced by alkaline concentration and extraction times

NASA Astrophysics Data System (ADS)

Mafazah, E. M.; Pranoto, Y.; Rohman, A.

2018-03-01

Yellowfin tuna (Thunnus albacares) skin is a by-product of the fish processing industry. Yellowfin tuna skin was used as materials for gelatin because it contains collagen. This study was conducted to determine the characteristics of yellowfin tuna skin gelatin (YSG). In this study, YSG was obtained by the extraction process in 0.01 M NaOH solution for 12 h. The results show that the yield of YSG was 12.49 % dry basis, with the gel strength of 291.73 g Bloom, viscosity of 8.6 cPs and melting point of 35 °C. The gel strength and melting point of YSG were lower than commercial bovine gelatin (CBG), which was 309.7401 g Bloom and 36.33 °C, respectively. However, the viscosity of YSG was higher than the CBG which was 5.6 cPs.

In situ probing of pulsed laser melting and laser-induced periodic surface structures formation by dynamic reflectivity

NASA Astrophysics Data System (ADS)

Huynh, T. T. D.; Semmar, N.

2017-09-01

The melting process and nanostructure formation induced by nanosecond and picosecond laser pulses on bulk silicon and copper thin film were studied by ex situ analysis and in situ real time reflectivity. Three different probing wavelengths (633, 473 and 326 nm) were used during the pump laser processing and were correlated to the beam parameters (pulse duration, laser fluence and number of laser shots) and copper thin film thickness. On a silicon surface using a KrF laser beam (27 ns, 1 Hz, 248 nm), the melting threshold was determined close to 700 mJ cm-2 and the melting duration increased from 10 to 130 ns as the fluence increased from 700 to 1750 mJ cm-2. Nanostructures with a spatial period close to the laser wavelength were formed on both copper thin film and silicon substrate after nanosecond Nd:YAG laser (10 ns, 266 nm, 1 Hz) irradiation. In the picosecond regime, using an Nd:YAG laser (40 ps, 266 nm, 1 Hz), different nanostructures, from spikes to laser-induced periodic surface structures, were formed on 500 nm copper thin film and were analyzed with respect to the drop in dynamic reflectivity changes versus the number of laser shots.

The Application of Thermal Plasma to Extraction Metallurgy and Related Fields

NASA Technical Reports Server (NTRS)

Akashi, K.

1980-01-01

Various applications of thermal plasma to extraction metallurgy and related fields are surveyed, chiefly on the basis of documents published during the past two or three years. Applications to melting and smelting, to thermal decomposition, to reduction, to manufacturing of inorganic compounds, and to other fields are considered.

Anisocoria Secondary to Anticholinergic Mydriasis from Homeopathic Pink Eye Relief Drops.

PubMed

Chen, Lin; Yeung, Joseph C; Anderson, Dennis R

2017-12-01

A woman, aged 70 years, developed anisocoria after applying homeopathic eye drops (Similasan Pink Eye Relief) to her left eye. Her pupil was dilated for two weeks and did not respond to light or near stimuli for one week. Both 0.1% and 1% pilocarpine failed to constrict her left pupil, and magnetic resonance imaging of her brain did not reveal any abnormality. The eye drops she had used contain belladonna extracts which have a natural atropine component. This case demonstrates the importance, when evaluating a patient presenting with anisocoria, of knowing the chemical ingredients of the homeopathic eye drops, which often are not listed. © 2017 Marshfield Clinic.

Melting and Reactive Flow of Carbonated Peridotite Beneath Mid-Ocean Ridges

NASA Astrophysics Data System (ADS)

Keller, T.; Katz, R. F.

2015-12-01

The mantle carbon reservoir is four orders of magnitude more massive than that of the atmosphere and ocean combined. The behaviour of carbon in the mantle, especially its transport and extraction, is thus of crucial importance to understanding the coupling between the deep interior and the surface environment of Earth. Laboratory experiments indicate that even small concentrations of carbon dioxide (and other volatiles like H2O) in the upper mantle significantly affect silicate melting [HK96,DH06] by stabilising carbon-rich melt at high pressure. The presence of carbon in the mantle substantially extends the region where partial melt is stable and has important consequences for the dynamics of magma transport and chemical differentiation [H10,DH10]. We have developed theory and numerical implementation to simulate thermo-chemically coupled magma/mantle dynamics in terms of a two-phase (rock+melt), three component (dunite+MORB+carbonated MORB) physical model. The fluid dynamics is based on McKenzie's equations [McK84]. The thermo-chemical formulation of the system is represented by a novel, disequilibrium, multi-component melting model based on thermodynamic theory [RBS11]. This physical model is implemented as a parallel, two-dimensional, finite-volume code that leverages tools from the PETSc toolkit. First results show that carbon and other volatiles cause a qualitative difference to the style of melt transport, potentially enhancing its extraction efficiency - measured in the carbon mass flux arriving at the mid-ocean ridge axis - by at least an order of magnitude. The process that controls magma transport in our models is a volatile flux-induced reactive infiltration instability, causing carbonated melt to rise from depth in localized channels. These results add to our understanding of melt formation and transport at mid-ocean ridges (the most important magmatic system in the mantle) and may have important implications for subduction zones. REFERENCESHK96 Hirth & Kohlstedt (1996), EPSLDH06 Dasgupta & Hirschmann (2006), NatureH10 Hirschmann (2010), PEPI DH10 Dasgupta & Hirschmann (2010), EPSLMcK84 McKenzie (1984), J PetKW12 Katz & Weatherley (2012), EPSLRBS11 Rudge, Bercovici & Spiegelman (2011), GJI

Nanorheology of Entangled Polymer Melts

DOE PAGES

Ge, Ting; Grest, Gary S.; Rubinstein, Michael

2018-02-01

In this study, we use molecular simulations to probe the local viscoelasticity of an entangled polymer melt by tracking the motion of embedded nonsticky nanoparticles (NPs). As in conventional microrheology, the generalized Stokes-Einstein relation is employed to extract an effective stress relaxation function G GSE(t) from the mean square displacement of NPs. G GSE(t) for different NP diameters d are compared with the stress relaxation function G(t) of a pure polymer melt. The deviation of G GSE(t) from G(t) reflects the incomplete coupling between NPs and the dynamic modes of the melt. For linear polymers, a plateau in G GSE(t)more » emerges as d exceeds the entanglement mesh size a and approaches the entanglement plateau in G(t) for a pure melt with increasing d. For ring polymers, as d increases towards the spanning size R of ring polymers, G GSE(t) approaches G(t) of the ring melt with no entanglement plateau.« less

Nanorheology of Entangled Polymer Melts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ge, Ting; Grest, Gary S.; Rubinstein, Michael

In this study, we use molecular simulations to probe the local viscoelasticity of an entangled polymer melt by tracking the motion of embedded nonsticky nanoparticles (NPs). As in conventional microrheology, the generalized Stokes-Einstein relation is employed to extract an effective stress relaxation function G GSE(t) from the mean square displacement of NPs. G GSE(t) for different NP diameters d are compared with the stress relaxation function G(t) of a pure polymer melt. The deviation of G GSE(t) from G(t) reflects the incomplete coupling between NPs and the dynamic modes of the melt. For linear polymers, a plateau in G GSE(t)more » emerges as d exceeds the entanglement mesh size a and approaches the entanglement plateau in G(t) for a pure melt with increasing d. For ring polymers, as d increases towards the spanning size R of ring polymers, G GSE(t) approaches G(t) of the ring melt with no entanglement plateau.« less

The importance of accurate interaction potentials in the melting of argon nanoclusters

NASA Astrophysics Data System (ADS)

Pahl, E.; Calvo, F.; Schwerdtfeger, P.

The melting temperatures of argon clusters ArN (N = 13, 55, 147, 309, 561, and 923) and of bulk argon have been obtained from exchange Monte Carlo simulations and are compared using different two-body interaction potentials, namely the standard Lennard-Jones (LJ), Aziz and extended Lennard-Jones (ELJ) potentials. The latter potential has many advantages: while maintaining the computational efficiency of the commonly used LJ potential, it is as accurate as the Aziz potential but the computer time scales more favorably with increasing cluster size. By applying the ELJ form and extrapolating the cluster data to the infinite system, we are able to extract the melting point of argon already in good agreement with experimental measurements. By considering the additional Axilrod-Teller three-body contribution as well, we calculate a melting temperature of T meltELJ = 84.7 K compared to the experimental value of T meltexp = 83.85 K, whereas the LJ potential underestimates the melting point by more than 7 K. Thus melting temperatures within 1 K accuracy are now feasible.

A hydrodynamic mechanism of meteor ablation. The melt-spraying model

NASA Astrophysics Data System (ADS)

Girin, Oleksandr G.

2017-10-01

Context. Hydrodynamic conditions are similar in a molten meteoroid and a liquid drop in a high-speed airflow. Despite the fact that the latter is well-studied, both experimentally and theoretically, hydrodynamic instability theory has not been applied to study the fragmentation of molten meteoroids. Aims: We aim to treat quasi-continuous spraying of meteoroid melt due to hydrodynamic instability as a possible mechanism of ablation. Our objectives are to calculate the time development of particle release, the released particle sizes and their distribution by sizes, as well as the meteoroid mass loss law. Methods: We have applied gradient instability theory to model the behaviour of the meteoroid melt layer and its interaction with the atmosphere. We have assumed a spherical meteoroid and that the meteoroid has a shallow entry angle, such that the density of the air stream interacting with the meteoroid is nearly constant. Results: High-frequency spraying of the molten meteoroid is numerically simulated. The intermediate and final size distributions of released particles are calculated, as well as the meteoroid mass loss law. Fast and slow meteoroids of iron and stone compositions are modelled, resulting in significant differences in the size distribution of melt particles sprayed from each meteoroid. Less viscous iron melt produces finer particles and a denser aerosol wake than a stony one does. Conclusions: Analysis of the critical conditions for the gradient instability mechanism shows that the dynamic pressure of the air-stream at heights up to 100 km is sufficient to overcome surface tension forces and pull out liquid particles from the meteoroid melt by means of unstable disturbances. Hence, the proposed melt-spraying model is able to explain quasi-continuous mode of meteoroid fragmentation at large heights and low dynamic pressures. A closed-form solution of the meteoroid ablation problem is obtained due to the melt-spraying model usage, at the meteoroid composition, initial radius and velocity being given. The movies associated to Figs. 6 and 7 are available at http://www.aanda.org

Temperature of Earth's core constrained from melting of Fe and Fe0.9Ni0.1 at high pressures

NASA Astrophysics Data System (ADS)

Zhang, Dongzhou; Jackson, Jennifer M.; Zhao, Jiyong; Sturhahn, Wolfgang; Alp, E. Ercan; Hu, Michael Y.; Toellner, Thomas S.; Murphy, Caitlin A.; Prakapenka, Vitali B.

2016-08-01

The melting points of fcc- and hcp-structured Fe0.9Ni0.1 and Fe are measured up to 125 GPa using laser heated diamond anvil cells, synchrotron Mössbauer spectroscopy, and a recently developed fast temperature readout spectrometer. The onset of melting is detected by a characteristic drop in the time-integrated synchrotron Mössbauer signal which is sensitive to atomic motion. The thermal pressure experienced by the samples is constrained by X-ray diffraction measurements under high pressures and temperatures. The obtained best-fit melting curves of fcc-structured Fe and Fe0.9Ni0.1 fall within the wide region bounded by previous studies. We are able to derive the γ-ɛ-l triple point of Fe and the quasi triple point of Fe0.9Ni0.1 to be 110 ± 5GPa, 3345 ± 120K and 116 ± 5GPa, 3260 ± 120K, respectively. The measured melting temperatures of Fe at similar pressure are slightly higher than those of Fe0.9Ni0.1 while their one sigma uncertainties overlap. Using previously measured phonon density of states of hcp-Fe, we calculate melting curves of hcp-structured Fe and Fe0.9Ni0.1 using our (quasi) triple points as anchors. The extrapolated Fe0.9Ni0.1 melting curve provides an estimate for the upper bound of Earth's inner core-outer core boundary temperature of 5500 ± 200K. The temperature within the liquid outer core is then approximated with an adiabatic model, which constrains the upper bound of the temperature at the core side of the core-mantle boundary to be 4000 ± 200K. We discuss a potential melting point depression caused by light elements and the implications of the presented core-mantle boundary temperature bounds on phase relations in the lowermost part of the mantle.

Temperature of Earth's core constrained from melting of Fe and Fe 0.9Ni 0.1 at high pressures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Dongzhou; Jackson, Jennifer M.; Zhao, Jiyong

The melting points of fcc- and hcp-structured Fe 0.9Ni 0.1 and Fe are measured up to 125 GPa using laser heated diamond anvil cells, synchrotron Mossbauer spectroscopy, and a recently developed fast temperature readout spectrometer. The onset of melting is detected by a characteristic drop in the time integrated synchrotron Mfissbauer signal which is sensitive to atomic motion. The thermal pressure experienced by the samples is constrained by X-ray diffraction measurements under high pressures and temperatures. The obtained best-fit melting curves of fcc-structured Fe and Fe 0.9Ni 0.1 fall within the wide region bounded by previous studies. We are ablemore » to derive the gamma-is an element of-1 triple point of Fe and the quasi triple point of Fe0.9Ni0.1 to be 110 ± 5 GPa, 3345 ± 120 K and 116 ± 5 GPa, 3260 ± 120 K, respectively. The measured melting temperatures of Fe at similar pressure are slightly higher than those of Fe 0.9Ni 0.1 while their one sigma uncertainties overlap. Using previously measured phonon density of states of hcp-Fe, we calculate melting curves of hcp-structured Fe and Fe 0.9Ni 0.1 using our (quasi) triple points as anchors. The extrapolated Fe 0.9Ni 0.1 melting curve provides an estimate for the upper bound of Earth's inner core-outer core boundary temperature of 5500 ± 200 K. The temperature within the liquid outer core is then approximated with an adiabatic model, which constrains the upper bound of the temperature at the core side of the core -mantle boundary to be 4000 ± 200 K. We discuss a potential melting point depression caused by light elements and the implications of the presented core -mantle boundary temperature bounds on phase relations in the lowermost part of the mantle.« less

Measurement of Attenuation with Airborne and Ground-Based Radar in Convective Storms Over Land Its Microphysical Implications

NASA Technical Reports Server (NTRS)

Tian, Lin; Heymsfield, G. M.; Srivastava, R. C.; O'C.Starr, D. (Technical Monitor)

2001-01-01

Observations by the airborne X-band Doppler radar (EDOP) and the NCAR S-band polarimetric (S-Pol) radar from two field experiments are used to evaluate the surface reference technique (SRT) for measuring the path integrated attenuation (PIA) and to study attenuation in deep convective storms. The EDOP, flying at an altitude of 20 km, uses a nadir beam and a forward pointing beam. It is found that over land, the surface scattering cross-section is highly variable at nadir incidence but relatively stable at forward incidence. It is concluded that measurement by the forward beam provides a viable technique for measuring PIA using the SRT. Vertical profiles of peak attenuation coefficient are derived in two deep convective storms by the dual-wavelength method. Using the measured Doppler velocity, the reflectivities at the two wavelengths, the differential reflectivity and the estimated attenuation coefficients, it is shown that: supercooled drops and (dry) ice particles probably co-existed above the melting level in regions of updraft, that water-coated partially melted ice particles probably contributed to high attenuation below the melting level.

Morphological characteristics of waste polyethylene/polypropylene plastics during pyrolysis and representative morphological signal characterizing pyrolysis stages.

PubMed

Wang, H; Chen, D; Yuan, G; Ma, X; Dai, X

2013-02-01

In this work, the morphological characteristics of waste polyethylene (PE)/polypropylene (PP) plastics during their pyrolysis process were investigated, and based on their basic image changing patterns representative morphological signals describing the pyrolysis stages were obtained. PE and PP granules and films were used as typical plastics for testing, and influence of impurities was also investigated. During pyrolysis experiments, photographs of the testing samples were taken sequentially with a high-speed infrared camera, and the quantitative parameters that describe the morphological characteristics of these photographs were explored using the "Image Pro Plus (v6.3)" digital image processing software. The experimental results showed that plastics pyrolysis involved four stages: melting, two stages of decomposition which are characterized with bubble formation caused by volatile evaporating, and ash deposition; and each stage was characterized with its own phase changing behaviors and morphological features. Two stages of decomposition are the key step of pyrolysis since they took up half or more of the reaction time; melting step consumed another half of reaction time in experiments when raw materials were heated up from ambient temperatures; and coke-like deposition appeared as a result of decomposition completion. Two morphological signals defined from digital image processing, namely, pixel area of the interested reaction region and bubble ratio (BR) caused by volatile evaporating were found to change regularly with pyrolysis stages. In particular, for all experimental scenarios with plastics films and granules, the BR curves always exhibited a slowly drop as melting started and then a sharp increase followed by a deep decrease corresponding to the first stage of intense decomposition, afterwards a second increase - drop section corresponding to the second stage of decomposition appeared. As ash deposition happened, the BR dropped to zero or very low values. When impurities were involved, the shape of BR curves showed that intense decomposition started earlier but morphological characteristics remained the same. In addition, compared to parameters such as pressure, the BR reflects reaction stages better and its change with pyrolysis process of PE/PP plastics with or without impurities was more intrinsically process correlated; therefore it can be adopted as a signal for pyrolysis process characterization, as well as offering guide to process improvement and reactor design. Copyright © 2012 Elsevier Ltd. All rights reserved.

A review of volatile compounds in tektites, and carbon content and isotopic composition of moldavite glass

NASA Astrophysics Data System (ADS)

Žák, Karel; SkáLA, Roman; Šanda, Zdeněk.; Mizera, Jiří.

2012-06-01

Tektites, natural silica-rich glasses produced during impact events, commonly contain bubbles. The paper reviews published data on pressure and composition of a gas phase contained in the tektite bubbles and data on other volatile compounds which can be released from tektites by either high-temperature melting or by crushing or milling under vacuum. Gas extraction from tektites using high-temperature melting generally produced higher gas yield and different gas composition than the low-temperature extraction using crushing or milling under vacuum. The high-temperature extraction obviously releases volatiles not only from the bubbles, but also volatile compounds contained directly in the glass. Moreover, the gas composition can be modified by reactions between the released gases and the glass melt. Published data indicate that besides CO2 and/or CO in the bubbles, another carbon reservoir is present directly in the tektite glass. To clarify the problem of carbon content and carbon isotopic composition of the tektite glass, three samples from the Central European tektite strewn field—moldavites—were analyzed. The samples contained only 35-41 ppm C with δ13C values in the range from -28.5 to -29.9‰ VPDB. This indicates that terrestrial organic matter was a dominant carbon source during moldavite formation.

Rapid hydrothermal cooling above the axial melt lens at fast-spreading mid-ocean ridge

NASA Astrophysics Data System (ADS)

Zhang, Chao; Koepke, Juergen; Kirchner, Clemens; Götze, Niko; Behrens, Harald

2014-09-01

Axial melt lenses sandwiched between the lower oceanic crust and the sheeted dike sequences at fast-spreading mid-ocean ridges are assumed to be the major magma source of oceanic crust accretion. According to the widely discussed ``gabbro glacier'' model, the formation of the lower oceanic crust requires efficient cooling of the axial melt lens, leading to partial crystallization and crystal-melt mush subsiding down to lower crust. These processes are believed to be controlled by periodical magma replenishment and hydrothermal circulation above the melt lens. Here we quantify the cooling rate above melt lens using chemical zoning of plagioclase from hornfelsic recrystallized sheeted dikes drilled from the East Pacific at the Integrated Ocean Drilling Program Hole 1256D. We estimate the cooling rate using a forward modelling approach based on CaAl-NaSi interdiffusion in plagioclase. The results show that cooling from the peak thermal overprint at 1000-1050°C to 600°C are yielded within about 10-30 years as a result of hydrothermal circulation above melt lens during magma starvation. The estimated rapid hydrothermal cooling explains how the effective heat extraction from melt lens is achieved at fast-spreading mid-ocean ridges.

Thermophysical properties of liquid Ni around the melting temperature from molecular dynamics simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rozas, R. E.; Department of Physics, University of Bío-Bío, Av. Collao 1202, P.O. Box 5C, Concepción; Demiraǧ, A. D.

Thermophysical properties of liquid nickel (Ni) around the melting temperature are investigated by means of classical molecular dynamics (MD) simulation, using three different embedded atom method potentials to model the interactions between the Ni atoms. Melting temperature, enthalpy, static structure factor, self-diffusion coefficient, shear viscosity, and thermal diffusivity are compared to recent experimental results. Using ab initio MD simulation, we also determine the static structure factor and the mean-squared displacement at the experimental melting point. For most of the properties, excellent agreement is found between experiment and simulation, provided the comparison relative to the corresponding melting temperature. We discuss themore » validity of the Hansen-Verlet criterion for the static structure factor as well as the Stokes-Einstein relation between self-diffusion coefficient and shear viscosity. The thermal diffusivity is extracted from the autocorrelation function of a wavenumber-dependent temperature fluctuation variable.« less

Critical porosity of melt segregation during crustal melting: Constraints from zonation of peritectic garnets in a dacite volcano

NASA Astrophysics Data System (ADS)

Yu, Xun; Lee, Cin-Ty A.

2016-09-01

The presence of leucogranitic dikes in orogenic belts suggests that partial melting may be an important process in the lower crust of active orogenies. Low seismic velocity and low electrical resistivity zones have been observed in the lower crust of active mountain belts and have been argued to reflect the presence of partial melt in the deep crust, but volcanoes are rare or absent above many of these inferred melt zones. Understanding whether these low velocity zones are melt-bearing, and if so, why they do not commonly erupt, is essential for understanding the thermal and rheologic structure of the crust and its dynamic evolution. Central to this problem is an understanding of how much melt can be stored before it can escape from the crust via compaction and eventually erupt. Experimental and theoretical studies predict trapped melt fractions anywhere from <5% to >30%. Here, we examine Mn growth-zoning in peritectic garnets in a Miocene dacite volcano from the ongoing Betic-Rif orogeny in southern Spain to estimate the melt fraction at the time of large-scale melt extraction that subsequently led to eruption. We show that the melt fraction at segregation, corresponding approximately to the critical melt porosity, was ∼30%, implying significant amounts of melt can be stored in the lower crust without draining or erupting. However, seismic velocities in the lower crust beneath active orogenic belts (southern Spain and Tibet) as well as beneath active magmatic zones (e.g., Yellowstone hotspot) correspond to average melt porosities of <10%, suggesting that melt porosities approaching critical values are short-lived or that high melt porosity regions are localized into heterogeneously distributed sills or dikes, which individually cannot be resolved by seismic studies.

A Spectroscopic Study On Two Glasses With Different Vesicularity From The Astroni Tephra (phlegraean Fields, Italy): Implications On Bubble Expansion

NASA Astrophysics Data System (ADS)

Slejko, F. F.; Petrini, R.

Bubble growth in ascending viscous magmas by volatile exsolution from the melt structure is important in causing the magma fragmentation which determines the trans- form from a lava flow to a pyroclastic explosion. Volatile solubility and speciation in the melt vary during pressure and temperature changes. The pressure drop which oc- curs as a magma rises towards the surface in a volcanic conduit, causes the release of the volatiles dissolved in the melt and the progressive growth in the size of bubbles against the retarding forces to expansion generated by the polymeric interconnections in the silicate melt structure. At some critical growth rate with respect to the relax- ation time of the melt structure, the disruption of the interbubbles walls in the melt marks the fragmentation threshold, with the transition from a viscous bubbly liquid to a fast-uprising gas carrying on fragments of vesiculated magma. Highly polymer- ized, silica-rich melts are characterised by relaxation times which may be long com- pared to the quick growth and deformation of bubbles during rapid magma decom- pression and cooling, and the glassy pumices which form may retain informations on the vesiculation and degassing processes which occurred close to the fragmentation depth. Furthermore, the formation of vesicles during the cooling and decompression of an ascending volatile-supersaturated high-silica magma is strongly favoured by the occurrence of bubble nucleating sites in the melt. In order to investigate the influ- ence of the structure and iron speciation on bubble growth during explosive volcan- ism, a dense glass and a vesiculated pumice glass coexisting in the same pyroclastic unit of the Astroni volcano tephra in the Phlegraean Fields Caldera (4.1-3.8 ka BP) were investigated by 29Si 2D phase adjusted spinning sidebands (PASS) NMR, 1H MAS NMR, electron spin resonance (ESR) and Mössbauer spectroscopy. 29Si 2D PASS spectra show that silicon copolymerizes in the structure dominantly by Q3 and Q4 groups, with partly overlapping chemical shift. Spectrum fittings indicate that the dense glass is characterised by a larger abundance of Q3 species compared to the vesiculated pumice, suggesting a less polymerized structure. 1H MAS spectra reveal a larger amount of hydrogen concentration in the dense glass, partly attributable to structural hydroxyl groups possibly in Q3-OH terminations depolymerizing the glass structure. The less polymerized structure of the dense glass could have allowed an easier volatile exsolution, preventing the bubble formation. The EPR spectra indicate that the Fe3+ has similar surroundings in both samples, suggesting that Fe3+ is likely to occur in both network forming and modifying sites. Nevertheless, the vesiculated glass is characterised by a significantly higher amount of magnetite particles, which could have enhanced the bubble nucleation. Mössbauer spectra show four doublets attributable to ferric iron in both tetrahedral and octahedral sites and ferrous iron only in octahedral coordination. The oxidation of Fe2+ to Fe3+ observed in the vesicu- lated glass with respect to the dense glass could be an evidence of pressure drop with consequent bubble expansion.

Effect of fO2 on phase relationship in basaltic andesites during magmatic differentiation: Control of fO2 and sulphur speciation in piston cylinder experiments.

NASA Astrophysics Data System (ADS)

Matjuschkin, Vladimir; Tattitch, Brian; Blundy, Jonathan D.; Skora, Susanne

2014-05-01

Within the mantle wedge above subduction zones, oxidation reaction take place by interaction of reduced mantle rocks with more oxidized, hydrous fluids, which can cause a local drop of the solidus, resulting in partial melting (2,6,7). The resultant melts are more oxidized that their ocean floor counterparts, which has implications for their subsequent differentiation paths, the speciation of multivalent elements and the solubility and transport of chemical compounds in magmatic systems (1,4,5). We present a series of sulphur-doped high-pressure experiments conducted to investigate the effect of oxygen fugacity on phase relationships and the behaviour of sulphur in silicate melts. Natural aphyric andesite (FM37) erupted from Laguna del Maule volcano, Chile (3) was selected as a starting composition. Experiments were carried out at 5kbar, 950-1150° C and variable oxygen fugacity conditions. New experiments buffered at Co-CoO and Ni-NiO buffer conditions have been performed using a new "MTB capsule design" developed in order to accurately control fO2 by means of a double capsule containing metal-oxide buffers and a pyrex sleeve to minimise H2 diffusion. This new design constrains oxygen fugacity to within ±0.1-0.2logfO2 units of the target value. Before conducting these experiments, the assemblage was tested multiple times at 10kbar, 1000° C over 24-48 hours and demonstrated consistent, accurate fO2 control. Analyses of the preliminary experimental run products, from a related Chilean basaltic andesite starting composition, demonstrate a clear effect of fO2 on phase relationships and the proportion of melt generated during experiments. Under oxidized conditions, as temperature decreased from 1150° C to 1050° C, the amount of melt decreased from 100% to ~80%, due to the formation of orthopyroxene, anhydrite and plagioclase. In contrast, in reduced runs the system remains nearly liquid (~5% crystals) down to 950° C due to the change in sulphur speciation and onset of orthopyroxene precipitation at much lower temperatures. The change in temperature from 1150 to 950° C resulted in a drop in S content from ~2500ppm to ~1000ppm in the melt for oxidized experiments, whereas S slightly increased from ~3000 to ~3500ppm in the reduced experiments. Quantitative control over fO2 will allow for more precise determination of phase relations and control of sulphur specification, offering a possibility of detailed reconstruction of metals enrichment in silicate melts. Cited references: [1] Botcharnikov et al. (2011) Nature 4:217-230, [2] Foley (2011) J Petrol 52:1363-1391, [3] Frey et al. (1984) CMP 88:133-149, [4] Jenner et al. (2010) J Petrol 51:2445-2464, [5] Jugo et al. (2010) GCA 74:5926-5938, [6] Rohrbach et al. (2007) Nature 449:456-458, [7] Taylor and Green (1988) Nature 332:349-352

Diffusive loss of argon in response to melt vein formation in polygenetic impact melt breccias

NASA Astrophysics Data System (ADS)

Mercer, Cameron M.; Hodges, Kip V.

2017-08-01

Many planetary surfaces in the solar system have experienced prolonged bombardment. With each impact, new rocks can be assembled that incorporate freshly generated impact melts with fragments of older rocks. Some breccias can become polygenetic, containing multiple generations of impact melt products, and can potentially provide important insights into the extensive bombardment history of a region. However, the amount of chronological information that can be extracted from such samples depends on how well the mineral isotopic systems of geochronometers can preserve the ages of individual melt generations without being disturbed by younger events. We model the thermal evolution of impact melt veins and the resulting loss of Ar from K-bearing phases common in impact melt breccias to assess the potential for preserving the 40Ar/39Ar ages of individual melt generations. Our model results demonstrate that millimeter-scale, clast-free melt veins cause significant heating of adjacent host rock minerals and can cause detectable Ar loss in contact zones that are generally thinner than, and at most about the same thickness as, the vein width. The incorporation of cold clasts in melt veins reduces the magnitudes of heating and Ar loss in the host rocks, and Ar loss can be virtually undetectable for sufficiently clast-rich veins. Quantitative evidence of the timing of impacts, as measured with the 40Ar/39Ar method, can be preserved in polygenetic impact melt breccias, particularly for those containing millimeter-scale bodies of clast-bearing melt products.

Densified Biomass as an Alternative Army Heating and Power Plant Fuel.

DTIC Science & Technology

1980-03-01

during all fuel handling operations, par- ticularly where there were long drops-in the elevator Rock Island Arsenall, IL pit and bunker area , for...intebkrmoeha3dysndvrgsaou an effective grate area of 90 sq ft (8.4 in2). The stoker consists of two independent, self-cleaning, automatic! 1 day. manual, heat...the pellet/fines quantity of free moisture from melting snow during mixture was distributed into the designated area of outside storage. the bunker

Camphor-Crataegus berry extract combination dose-dependently reduces tilt induced fall in blood pressure in orthostatic hypotension.

PubMed

Belz, G G; Butzer, R; Gaus, W; Loew, D

2002-10-01

In order to test the efficacy of a combination of natural D-camphor and an extract of fresh crataegus berries (Korodin Herz-Kreislauf-Tropfen) on orthostatic hypotension, two similar, controlled, randomized studies were carried out in a balanced crossover design in 24 patients each with orthostatic dysregulation. The camphor-crataegus berry combination (CCC) was orally administered as a single regimen in 3 different dosages of 5 drops, 20 drops and 80 drops; a placebo with 20 drops of a 60% alcoholic solution served as control. Orthostatic hypotension was assessed with the tilt table test before and after medication. Source data of both studies were pooled and meta-analytically evaluated for all 48 patients. CCC drops decreased the orthostatic fall in blood pressure versus placebo, as almost uniformly established at all times by mean arterial pressure and diastolic blood pressure. Mean arterial pressure demonstrated the very fast onset of action by a clearly dose-dependent statistically significant effect even after 1-minute orthostasis. Increase of mean arterial pressure as compared to the orthostasis test before medication was on average 4.5 mmHg. CCC affected diastolic blood pressure after 1 minute of orthostasis in all dosages as compared to placebo. A statistically significant effect of the highest dose of 80 drops on diastolic blood pressure could be demonstrated after 1-, 3-, and 5-minute orthostasis. The hemodynamic findings of a stabilizing effect on arterial pressure in orthostasis corroborate the long-term medical experience with CCC and justify the indication orthostatic hypotension.

Constitutive relationships and physical basis of fault strength due to flash heating

USGS Publications Warehouse

Beeler, N.M.; Tullis, T.E.; Goldsby, D.L.

2008-01-01

We develop a model of fault strength loss resulting from phase change at asperity contacts due to flash heating that considers a distribution of contact sizes and nonsteady state evolution of fault strength with displacement. Laboratory faulting experiments conducted at high sliding velocities, which show dramatic strength reduction below the threshold for bulk melting, are well fit by the model. The predicted slip speed for the onset of weakening is in the range of 0.05 to 2 m/s, qualitatively consistent with the limited published observations. For this model, earthquake stress drops and effective shear fracture energy should be linearly pressure-dependent, whereas the onset speed may be pressure-independent or weakly pressure-dependent. On the basis of the theory, flash weakening is expected to produce large dynamic stress drops, small effective shear fracture energy, and undershoot. Estimates of the threshold slip speed, stress drop, and fracture energy are uncertain due to poor knowledge of the average ontact dimension, shear zone thickness and gouge particle size at seismogenic depths. Copyright 2008 by the American Geophysical Union.

Forming chondrules in impact splashes. I. Radiative cooling model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dullemond, Cornelis Petrus; Stammler, Sebastian Markus; Johansen, Anders

2014-10-10

The formation of chondrules is one of the oldest unsolved mysteries in meteoritics and planet formation. Recently an old idea has been revived: the idea that chondrules form as a result of collisions between planetesimals in which the ejected molten material forms small droplets that solidify to become chondrules. Pre-melting of the planetesimals by radioactive decay of {sup 26}Al would help produce sprays of melt even at relatively low impact velocity. In this paper we study the radiative cooling of a ballistically expanding spherical cloud of chondrule droplets ejected from the impact site. We present results from numerical radiative transfermore » models as well as analytic approximate solutions. We find that the temperature after the start of the expansion of the cloud remains constant for a time t {sub cool} and then drops with time t approximately as T ≅ T {sub 0}[(3/5)t/t {sub cool} + 2/5]{sup –5/3} for t > t {sub cool}. The time at which this temperature drop starts t {sub cool} depends via an analytical formula on the mass of the cloud, the expansion velocity, and the size of the chondrule. During the early isothermal expansion phase the density is still so high that we expect the vapor of volatile elements to saturate so that no large volatile losses are expected.« less

Deep structure of the Afro-Arabian hotspot by S receiver functions

NASA Astrophysics Data System (ADS)

Vinnik, L. P.; Farra, V.; Kind, R.

2004-06-01

We investigated deep structure of the Afro-Arabian hotspot by using recordings from Geoscope seismograph station ATD. The records are processed with the S receiver function technique, which allows a detection of Sp converted phases from the upper mantle discontinuities. The seismic data reveal two unusual discontinuities. The discontinuity at a depth of 160 km beneath the Gulf of Aden corresponds to the onset of melting. If the water content in olivine is around 800 H/106Si, melting at this depth requires a temperature close to 1550°C, about 120°C higher than the average. Another remarkable discontinuity is found at a depth of 480 km, where S velocity drops with depth by about 0.2 km/s. This can be the head of another plume which is trapped in the mantle transition zone.

Method and apparatus for supercooling and solidifying substances

NASA Technical Reports Server (NTRS)

Lacy, L. L.; Robinson, M. B.; Rathz, T. J.; Katz, L.; Nisen, D. B. (Inventor)

1983-01-01

An enclosure provides a containerless environment in which a sample specimen is positioned. The specimen is heated in the containerless environment, and the specimen melt is dropped through the tube in which it cools by radiation. The tube is alternatively backfilled with an inert gas whereby the specimen melt cools by both radiation and convection during its free fall. During the free fall, the sample is in a containerless, low-gravity environment which enhances supercooling in the sample and prevents sedimentation and thermal convection influences. The sample continues to supercool until nucleation occurs which is detected by silicon photovoltaic detectors. The sample solidifies after nucleation and becomes completely solid before entering the detachable catcher. The amount of supercooling of the specimen can be measured by knowing the cooling ratio and determining the time for nucleation to occur.

Efg Crystal Growth Apparatus And Method

DOEpatents

Mackintosh, Brian H.; Ouellette, Marc

2003-05-13

An improved mechanical arrangement controls the introduction of silicon particles into an EFG (Edge-defined Film-fed Growth) crucible/die unit for melt replenishment during a crystal growth run. A feeder unit injects silicon particles upwardly through a center hub of the crucible/die unit and the mechanical arrangement intercepts the injected particles and directs them so that they drop into the melt in a selected region of the crucible and at velocity which reduces splashing, whereby to reduce the likelihood of interruption of the growth process due to formation of a solid mass of silicon on the center hub and adjoining components. The invention also comprises use of a Faraday ring to alter the ratio of the electrical currents flowing through primary and secondary induction heating coils that heat the crucible die unit and the mechanical arrangement.

Influence of stretching and density contrasts on the chemical evolution of continental magmas: An example from the Ivrea-Verbano Zone

USGS Publications Warehouse

Sinigoi, S.; Quick, J.E.; Mayer, A.; Budahn, J.

1996-01-01

The southern Ivrea-Verbano Zone of the Italian Western Alps contains a huge mafic complex that intruded high-grade metamorphic rocks while they were resident in the lower crust. Geologic mapping and chemical variations of the igneous body were used to study the evolution of underplated crust. Slivers of crustal rocks (septa) interlayered with igneous mafic rocks are concentrated in a narrow zone deep in the complex (Paragneiss-bearing Belt) and show evidence of advanced degrees of partial melting. Variations of rare-earth-element patterns and Sr isotope composition of the igneous rocks across the sequence are consistent with increasing crustal contamination approaching the septa. Therefore, the Paragneiss-bearing Belt is considered representative of an "assimilation region" where in-situ interaction between mantle- and crust-derived magmas resulted in production of hybrid melts. Buoyancy caused upwards migration of the hybrid melts that incorporated the last septa and were stored at higher levels, feeding the Upper Mafic Complex. Synmagmatic stretching of the assimilation region facilitated mixing and homogenization of melts. Chemical variations of granitoids extracted from the septa show that deep septa are more depleted than shallow ones. This suggests that the first incorporated septa were denser than the later ones, as required by the high density of the first-injected mafic magmas. It is inferred that density contrasts between mafic melts and crustal rocks play a crucial role for the processes of contamination of continental magmas. In thick under- plated crust, the extraction of early felsic/hybrid melts from the lower crust may be required to increase the density of the lower crust and to allow the later mafic magmas to penetrate higher crustal levels.

Controls on melting at spreading ridges from correlated abyssal peridotite - mid-ocean ridge basalt compositions

NASA Astrophysics Data System (ADS)

Regelous, Marcel; Weinzierl, Christoph G.; Haase, Karsten M.

2016-09-01

Variations in the volume and major element composition of basalt erupted along the global mid-ocean ridge system have been attributed to differences in mantle potential temperature, mantle composition, or plate spreading rate and lithosphere thickness. Abyssal peridotites, the residues of mantle melting beneath mid-ocean ridges, provide additional information on the melting process, which could be used to test these hypotheses. We compiled a global database of abyssal peridotite compositions averaged over the same ridge segments defined by Gale et al. (2013). In addition, we calculated the distance of each ridge segment to the nearest hotspots. We show that Cr# in spinel in abyssal peridotites is negatively correlated with Na90 in basalts from the same ridge segments on a global scale. Ridge segments that erupt basalts apparently produced by larger degrees of mantle melting are thus underlain by peridotites from which large amounts of melt have been extracted. We find that near-ridge hotspots have a more widespread influence on mid-ocean ridge basalt (MORB) composition and ridge depth than previously thought. However, when these hotspot-influenced ridge segments are excluded, the remaining segments show clear relationships between MORB composition, peridotite composition, and ridge depth with spreading rate. Very slow-spreading ridges (<20 mm/yr) are deeper, erupt basalts with higher Na90, Al90, K90/Ti90, and lower Fe90, Ca90/Al90, and expose peridotites with lower Cr# than intermediate and fast-spreading ridges. We show that away from hotspots, the spreading-rate dependence of the maximum degree of mantle melting inferred from Cr# in peridotites (FM) and the bulk degree of melting inferred from Na90 in basalts (FB) from the same ridge segments is unlikely to be due to variations in mantle composition. Nor can the effects of dynamic mantle upwelling or incomplete melt extraction at low spreading rates satisfactorily explain the observed compositions of abyssal peridotites and MORB from very slow-spreading ridges. Instead, the distinctive compositions of abyssal peridotites and MORB from very slow-spreading ridges could result from the presence of a thick lithospheric lid, leading to a lower average degree of melting, and a higher contribution to melting from more fertile mantle lithologies. Alternatively, spreading rate influences the thermal structure of the upper mantle such that the mantle beneath very slow-spreading ridges is cooler.

The influence of glass fibers on elongational viscosity studied by means of optical coherence tomography and X-ray computed tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aigner, M., E-mail: michael.aigner@jku.at; Köpplmayr, T., E-mail: thomas.koepplmayr@jku.at, E-mail: Christian.lang@jku.at; Lang, C., E-mail: thomas.koepplmayr@jku.at, E-mail: Christian.lang@jku.at

2014-05-15

We report on the flow characteristics of glass-fiber-reinforced polymers in elongational rheometry. Unlike polymers with geometrically isotropic fillers, glass-fiber-reinforced polymers exhibit flow behavior and rheology that depend heavily on the orientation, the length distribution and the content of the fibers. One of the primary objectives of this study was to determine the effect of fiber orientation, concentration and distribution on the entrance pressure drop by means of optical coherence tomography (OCT), full-field optical coherence microscopy (FF-OCM), and X-ray computed tomography (X-CT). Both pressure drop and melt flow were analyzed using a special elongation die (Thermo Scientific X-Die [3]) for inlinemore » measurements. Samples with a variety of fiber volume fractions, fiber lengths and processing temperatures were measured.« less

Eutectic growth under acoustic levitation conditions.

PubMed

Xie, W J; Cao, C D; Lü, Y J; Wei, B

2002-12-01

Samples of Pb-Sn eutectic alloy with a high density of 8.5 x 10(3) kg/m(3) are levitated with a single-axis acoustic levitator, and containerlessly melted and then solidified in argon atmosphere. High undercoolings up to 38 K are obtained, which results in a microstructural transition of "lamellas-broken lamellas-dendrites." This transition is further investigated in the light of the coupled zone for eutectic growth and the effects of ultrasound. The breaking of regular eutectic lamellas and suppression of gravity-induced macrosegregation of (Pb) and (Sn) dendrites are explained by the complicated internal flow inside the levitated drop, which is jointly induced by the shape oscillation, bulk vibration and rotation of the levitated drop. The ultrasonic field is also found to drive forced surface vibration, which subsequently excites capillary ripples and catalyzes nucleation on the sample surface.

Noncontact surface tension and viscosity measurements of molten oxides with a pressurized hybrid electrostatic-aerodynamic levitator

NASA Astrophysics Data System (ADS)

Ishikawa, Takehiko; Yu, Jianding; Paradis, Paul-François

2006-05-01

In order to measure the surface tension and the viscosity of molten oxides, the oscillation drop technique has been applied on a pressurized hybrid electrostatic-aerodynamic levitator. To suppress the electrical discharge between the top and bottom electrodes, the drop excitation method which has been used with high vacuum electrostatic levitators has been modified. As a demonstration, the surface tension and viscosity of liquid BaTiO3 were measured using this new method. Over the 1500-2000K interval, the surface tension was measured as γ(T )=349-0.03 (T-Tm) (10-3N/m), where Tm=1893K is the melting temperature. Similarly, the viscosity was determined as η(T )=0.53exp[5.35×104/(RT)](10-3Pas) over the same temperature interval.

Eutectic growth under acoustic levitation conditions

NASA Astrophysics Data System (ADS)

Xie, W. J.; Cao, C. D.; Lü, Y. J.; Wei, B.

2002-12-01

Samples of Pb-Sn eutectic alloy with a high density of 8.5×103 kg/m3 are levitated with a single-axis acoustic levitator, and containerlessly melted and then solidified in argon atmosphere. High undercoolings up to 38 K are obtained, which results in a microstructural transition of ``lamellas-broken lamellas-dendrites.'' This transition is further investigated in the light of the coupled zone for eutectic growth and the effects of ultrasound. The breaking of regular eutectic lamellas and suppression of gravity-induced macrosegregation of (Pb) and (Sn) dendrites are explained by the complicated internal flow inside the levitated drop, which is jointly induced by the shape oscillation, bulk vibration and rotation of the levitated drop. The ultrasonic field is also found to drive forced surface vibration, which subsequently excites capillary ripples and catalyzes nucleation on the sample surface.

Headspace Single-Drop Microextraction Gas Chromatography Mass Spectrometry for the Analysis of Volatile Compounds from Herba Asari

PubMed Central

Wang, Guan-Jie; Tian, Li; Fan, Yu-Ming; Qi, Mei-Ling

2013-01-01

A rapid headspace single-drop microextraction gas chromatography mass spectrometry (SDME-GC-MS) for the analysis of the volatile compounds in Herba Asari was developed in this study. The extraction solvent, extraction temperature and time, sample amount, and particle size were optimized. A mixed solvent of n-tridecane and butyl acetate (1 : 1) was finally used for the extraction with sample amount of 0.750 g and 100-mesh particle size at 70°C for 15 min. Under the determined conditions, the pound samples of Herba Asari were directly applied for the analysis. The result showed that SDME-GC–MS method was a simple, effective, and inexpensive way to measure the volatile compounds in Herba Asari and could be used for the analysis of volatile compounds in Chinese medicine. PMID:23607049

Quantification of fungicides in snow-melt runoff from turf: A comparison of four extraction methods

USDA-ARS?s Scientific Manuscript database

A variety of pesticides are used to control diverse stressors to turf. These pesticides have a wide range in physical and chemical properties. The objective of this project was to develop an extraction and analysis method for quantification of chlorothalonil and PCNB (pentachloronitrobenzene), two p...

Sound velocity measurement of nuclear-ordered U2D2 solid 3He along the melting curve

NASA Astrophysics Data System (ADS)

Nomura, R.; Suzuki, M.; Yamaguchi, M.; Sasaki, Y.; Mizusaki, T.

2000-05-01

The sound velocity of a single-domain 3He crystal was measured in the nuclear-ordered low-field phase and the paramagnetic phase along the melting curve, using 10.98 MHz longitudinal sound. The temperature dependence of the sound velocity along the melting curve was explained by a nuclear spin contribution and the molar volume change along the melting curve. By comparing the measured velocity with thermodynamic quantities, we extracted the Grüneizen constant for the exchange energy. The anisotropy of the velocity in the ordered phase was investigated for three samples and was found to be smaller than 2×10 -5 in Δ v/ v. The attenuation coefficient of the sound was much smaller than 0.2 cm-1.

Hugoniot temperatures and melting of tantalum under shock compression determined by optical pyrometry

NASA Astrophysics Data System (ADS)

Dai, Chengda; Hu, Jianbo; Tan, Hua

2009-08-01

LiF single crystal was used as transparent window (anvil) to tamp the shock-induced free surface expansion of Ta specimen, and the Ta/LiF interface temperature was measured under shock compression using optical pyrometry technique. The shock temperatures and/or melting temperatures of Ta up to ˜400 GPa were extracted from the observed interface temperatures based on the Tan-Ahrens' model for one-dimensional heat conduction across metal/window ideal interface in which initial melting and subsequent solidification were considered under shock loading. The obtained data within the experimental uncertainties are consistent with the results from high-pressure sound velocity measurements. The temperature of the partial melting on Ta Hugoniot is estimated to be ˜9700 K at 300 GPa, supported by available results from theoretical calculations.

Origin of silicic magmas along the Central American volcanic front: Genetic relationship to mafic melts

NASA Astrophysics Data System (ADS)

Vogel, Thomas A.; Patino, Lina C.; Eaton, Jonathon K.; Valley, John W.; Rose, William I.; Alvarado, Guillermo E.; Viray, Ela L.

2006-09-01

Silicic pyroclastic flows and related deposits are abundant along the Central American volcanic front. These silicic magmas erupted through both the non-continental Chorotega block to the southeast and the Paleozoic continental Chortis block to the northwest. The along-arc variations of the silicic deposits with respect to diagnostic trace element ratios (Ba/La, U/Th, Ce/Pb), oxygen isotopes, Nd and Sr isotope ratios mimic the along-arc variation in the basaltic and andesitic lavas. This variation in the lavas has been interpreted to indicate relative contributions from the slab and asthenosphere to the basaltic magmas [Carr, M.J., Feigenson, M.D., Bennett, E.A., 1990. Incompatible element and isotopic evidence for tectonic control of source mixing and melt extraction along the Central American arc. Contributions to Mineralogy and Petrology, 105, 369-380.; Patino, L.C., Carr, M.J. and Feigenson, M.D., 2000. Local and regional variations in Central American arc lavas controlled by variations in subducted sediment input. Contributions to Mineralogy and Petrology, 138 (3), 265-283.]. With respect to along-arc trends in basaltic lavas the largest contribution of slab fluids is in Nicaragua and the smallest input from the slab is in central Costa Rica — similar trends are observed in the silicic pyroclastic deposits. Data from melting experiments of primitive basalts and basaltic andesites demonstrate that it is difficult to produce high K 2O/Na 2O silicic magmas by fractional crystallization or partial melting of low-K 2O/Na 2O sources. However fractional crystallization or partial melting of medium- to high-K basalts can produce these silicic magmas. We interpret that the high-silica magmas associated Central America volcanic front are partial melts of penecontemporaneous, mantle-derived, evolved magmas that have ponded and crystallized in the mid-crust — or are melts extracted from these nearly completely crystallized magmas.

Magnetostructural coupling and magnetocaloric effect in Ni-Mn-Ga-Cu microwires

NASA Astrophysics Data System (ADS)

Zhang, Xuexi; Qian, Mingfang; Zhang, Zhe; Wei, Longsha; Geng, Lin; Sun, Jianfei

2016-02-01

Ni-Mn-Ga-X microwires were produced by melt-extraction technique on a large scale. Their shape memory effect, superelasticity, and damping capacity have been demonstrated. Here, the excellent magnetocaloric effect was revealed in Ni-Mn-Ga-Cu microwires produced by melt-extraction and subsequent annealing. The overlap of the martensitic and magnetic transformations, i.e., magnetostructural coupling, was achieved in the annealed microwires. The magnetostructural coupling and wide martensitic transformation temperature range contribute to a large magnetic entropy change of -8.3 J/kg K with a wide working temperature interval of ˜13 K under a magnetic field of 50 kOe. Accordingly, a high refrigeration capacity of ˜78 J/kg was produced in the annealed microwires.

Microstructural Characterization of Melt Extracted High-Nb-Containing TiAl-Based Fiber

PubMed Central

Zhang, Shuzhi; Zhang, Shuling; Chen, Yanfei; Han, Jianchao; Zhang, Changjiang; Wang, Xiaopeng; Chen, Yuyong

2017-01-01

The microstructure of melt extracted Ti-44Al-8Nb-0.2W-0.2B-1.5Si fiber were investigated. When the rotation speed increased from 2000 to 2600 r/min, the appearance of the wire was uniform with no Rayleigh-wave default. The structure was mainly composed of fine α2 (α) phase dendritic crystal and a second phase between dendrite arms and grain boundaries. The precipitated second phases were confirmed to be Ti5Si3 from the eutectic reaction L→Ti5Si3 + α and TiB. As the lower content of Si and higher cooling rate, a divorced eutectic microstructure was obtained. Segregation of Ti, Nb, B, Si, and Al occurred during rapid solidification. PMID:28772555

Transient induced tungsten melting at the Joint European Torus (JET)

NASA Astrophysics Data System (ADS)

Coenen, J. W.; Matthews, G. F.; Krieger, K.; Iglesias, D.; Bunting, P.; Corre, Y.; Silburn, S.; Balboa, I.; Bazylev, B.; Conway, N.; Coffey, I.; Dejarnac, R.; Gauthier, E.; Gaspar, J.; Jachmich, S.; Jepu, I.; Makepeace, C.; Scannell, R.; Stamp, M.; Petersson, P.; Pitts, R. A.; Wiesen, S.; Widdowson, A.; Heinola, K.; Baron-Wiechec, A.; Contributors, JET

2017-12-01

Melting is one of the major risks associated with tungsten (W) plasma-facing components (PFCs) in tokamaks like JET or ITER. These components are designed such that leading edges and hence excessive plasma heat loads deposited at near normal incidence are avoided. Due to the high stored energies in ITER discharges, shallow surface melting can occur under insufficiently mitigated plasma disruption and so-called edge localised modes—power load transients. A dedicated program was carried out at the JET to study the physics and consequences of W transient melting. Following initial exposures in 2013 (ILW-1) of a W-lamella with leading edge, new experiments have been performed on a sloped surface (15{}\\circ slope) during the 2015/2016 (ILW-3) campaign. This new experiment allows significantly improved infrared thermography measurements and thus resolved important issue of power loading in the context of the previous leading edge exposures. The new lamella was monitored by local diagnostics: spectroscopy, thermography and high-resolution photography in between discharges. No impact on the main plasma was observed despite a strong increase of the local W source consistent with evaporation. In contrast to the earlier exposure, no droplet emission was observed from the sloped surface. Topological modifications resulting from the melting are clearly visible between discharges on the photographic images. Melt damage can be clearly linked to the infrared measurements: the emissivity drops in zones where melting occurs. In comparison with the previous leading edge experiment, no runaway melt motion is observed, consistent with the hypothesis that the escape of thermionic electrons emitted from the melt zone is largely suppressed in this geometry, where the magnetic field intersects the surface at lower angles than in the case of perpendicular impact on a leading edge. Utilising both exposures allows us to further test the model of the forces driving melt motion that successfully reproduced the findings from the original leading edge exposure. Since the ILW-1 experiments, the exposed misaligned lamella has now been retrieved from the JET machine and post mortem analysis has been performed. No obvious mass loss is observed. Profilometry of the ILW-1 lamella shows the structure of the melt damage which is in line with the modell predictions thus allowing further model validation. Nuclear reaction analysis shows a tenfold reduction in surface deuterium concentration in the molten surface in comparison to the non-molten part of the lamella.

Oxygen and iron production by electrolytic smelting of lunar soil

NASA Technical Reports Server (NTRS)

Colson, R. O.; Haskin, L. A.

1991-01-01

Oxygen, present in abundance in nearly all lunar materials, can theoretically be extracted by molten silicate electrolysis from any known lunar rock. Derivation of oxygen by this method has been amply demonstrated experimentally in silicate melts of a variety of compositions. This work can be divided into three categories: (1) measurement of solubilities of metals (atomic) in silicate melts; (2) electrolysis experiments under various conditions of temperature, container material, electrode configuration, current density, melt composition, and sample mass (100 to 2000 mg) measuring energy required and character of resulting products; and (3) theoretical assessment of compositional requirements for steady state operations of an electrolysis cell.

Surface layering and melting in an ionic liquid studied by resonant soft X-ray reflectivity

PubMed Central

Mezger, Markus; Ocko, Benjamin M.; Reichert, Harald; Deutsch, Moshe

2013-01-01

The molecular-scale structure of the ionic liquid [C18mim]+[FAP]− near its free surface was studied by complementary methods. X-ray absorption spectroscopy and resonant soft X-ray reflectivity revealed a depth-decaying near-surface layering. Element-specific interfacial profiles were extracted with submolecular resolution from energy-dependent soft X-ray reflectivity data. Temperature-dependent hard X-ray reflectivity, small- and wide-angle X-ray scattering, and infrared spectroscopy uncovered an intriguing melting mechanism for the layered region, where alkyl chain melting drove a negative thermal expansion of the surface layer spacing. PMID:23431181

A new method for separating first row transition metals and actinides from synthetic melt glass

DOE PAGES

Roman, Audrey Rae; Bond, Evelyn M.

2016-01-14

A new method was developed for separating Co, Fe, and Sc from complex debris matrices using the extraction chromatography resin DGA. The activation products Co-58, Mn-54, and Sc-46 were used to characterize the separation of the synthetic melt glass solutions. In the separation scheme that was developed, Au, Co, Cu, Fe, Sc, and Ti were separated from the rest of the sample constituents. In this paper, the synthetic melt glass separation method, efficiency, recoveries, and the length of procedure will be discussed. In conclusion, batch contact adsorption studies for Na and Sc for DGA resin are discussed as well.

Does patchouli oil change blood platelet monoamine oxidase-A activity of adult mammals?

PubMed

Karim, Md Fazlul; Banerjee, Soumyabrata; Poddar, Mrinal K

2018-05-01

Patchouli oil, an essential aroma oil extracted from patchouli leaf during short-term exposure with five and ten drops either inhibited (at 1 or 2 h) or stimulated (at 4 h) the platelet MAO-A activity depending on the dosages of the aroma oil mainly due to inhibition or stimulation of its K m . The long-term 15 consecutive days exposure (with two or five drops) of patchouli oil, on the other hand, maximally stimulated the platelet MAO-A activity with five drops patchouli oil for 1 h exposure, but further continuation of its exposure with same doses (two or five drops) for 30 consecutive days significantly stimulated (with two drops) and inhibited (with five drops) the platelet MAO-A activity due to stimulation and inhibition respectively of its corresponding both K m and V max . These results thus suggest that this aroma oil exposure may modulate the blood platelet serotonergic regulation depending on the dose, duration, and conditions of exposure.

Inviscid dynamics of a wet foam drop with monodisperse bubble size distribution

NASA Astrophysics Data System (ADS)

McDaniel, J. Gregory; Akhatov, Iskander; Holt, R. Glynn

2002-06-01

Motivated by recent experiments involving the acoustic levitation of foam drops, we develop a model for nonlinear oscillations of a spherical drop composed of monodisperse aqueous foam with void fraction below 0.1. The model conceptually divides a foam drop into many cells, each cell consisting of a spherical volume of liquid with a bubble at its center. By treating the liquid as incompressible and inviscid, a nonlinear equation is obtained for bubble motion due to a pressure applied at the outer radius of the liquid sphere. Upon linearizing this equation and connecting the cells at their outer radii, a wave equation is obtained with a dispersion relation for the sound waves in a bubbly liquid. For the spherical drop, this equation is solved by a normal mode expansion that yields the natural frequencies as functions of standard foam parameters. Numerical examples illustrate how the analysis may be used to extract foam parameters, such as void fraction and bubble radius, from the experimentally measured natural frequencies of a foam drop.

Final Technical Report: Electrohydrodynamic Tip Streaming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Basaran, Osman

2016-01-06

When subjected to strong electric fields, liquid drops and films form conical tips and emit thin jets from their tips. Such electrodydrodynamic (EDH) tip streaming or cone-jetting phenomena, which are sometimes referred to as electrospraying, occur widely in nature, e.g., in ejection of streams of small charged drops from pointed tips of raindrops in thunderclouds, and technology, e.g., in electrospray mass spectrometry or electric field-driven solvent extraction. More recently, EHD cone-jetting has emerged as a powerful technique for direct printing of solar cells, micro- and nano- particle production, and microencapsulation for controlled release. In many of the aforementioned situations, ofmore » equal importance to the processes by which one drop disintegrates to form several drops are those by which (a) two drops come together and coalesce and (b) two drops are coupled to form a double droplet system (DDS) or a capillary switch (CS). the main objective of this research program is to advance through simulation, theory, and experiment the breakup, coalescence, and oscillatory dynamics of single and pairs of charged as well as uncharged drops.« less

Attrition in trials evaluating complex interventions for schizophrenia: Systematic review and meta-analysis.

PubMed

Szymczynska, P; Walsh, S; Greenberg, L; Priebe, S

2017-07-01

Essential criteria for the methodological quality and validity of randomized controlled trials are the drop-out rates from both the experimental intervention and the study as a whole. This systematic review and meta-analysis assessed these drop-out rates in non-pharmacological schizophrenia trials. A systematic literature search was used to identify relevant trials with ≥100 sample size and to extract the drop-out data. The rates of drop-out from the experimental intervention and study were calculated with meta-analysis of proportions. Meta-regression was applied to explore the association between the study and sample characteristics and the drop-out rates. 43 RCTs were found, with drop-out from intervention ranging from 0% to 63% and study drop-out ranging from 4% to 71%. Meta-analyses of proportions showed an overall drop-out rate of 14% (95% CI: 13-15%) at the experimental intervention level and 20% (95% CI: 17-24%) at the study level. Meta-regression showed that the active intervention drop-out rates were predicted by the number of intervention sessions. In non-pharmacological schizophrenia trials, drop-out rates of less than 20% can be achieved for both the study and the experimental intervention. A high heterogeneity of drop-out rates across studies shows that even lower rates are achievable. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantitative characterization of 3-dimensional melt distribution in partially molten olivine-basalt aggregates using X-ray synchrotron microtomography

NASA Astrophysics Data System (ADS)

Zhu, W.; Gaetani, G. A.; Fusseis, F.

2009-12-01

Quantitative knowledge of the distribution of small amounts of silicate melt in peridotite and of its influence on permeability are critical to our understanding of melt migration and segregation processes in the upper mantle. Estimates for the permeability of partially molten rock require 3D melt distribution at the grain-scale. Existing studies of melt distribution, carried out on 2D slices through experimental charges, have produced divergent models for melt distribution at small melt fractions. While some studies conclude that small amounts of melt are distributed primarily along triple junctions [e.g., Wark et al., 2003], others predict an important role for melt distribution along grain boundaries at low melt fractions [e.g., Faul 1997]. Using X-ray synchrotron microtomography, we have obtained the first high quality non-destructive imaging of 3D melt distribution in olivine-basalt aggregates. Textually equilibrated partially molten samples consisting of magnesian olivine plus 2, 5, 10, or 20% primitive basalt were synthesized at 1.5 GPa and 1350°C in experiments lasting 264-336 hours. Microtomographic images of melt distribution were obtained on cylindrical cores, 1 mm in diameter, at a spatial resolution of 1 micron. Textual information such as melt channel size, dihedral angle and channel connectivity was then quantified using AVIZO and MATLAB. Our results indicate that as melt fraction decreases, melt becomes increasingly distributed along 3 grain junctions, in agreement with theoretical predictions. We do not find significant amounts of melt along grain boundaries at low melt fractions. We found that the true dihedral angle ranges from 50 to 70°, in agreements with results using 2D microcopy. Comparison between the samples provides a quantitative characterization of how melt fraction affects melt distribution including connectivity. The geometrical data have been incorporated into our network model to obtain macroscale transport properties for partially molten dunite. Results from this tomographic study thus provide constraints on rates of melt migration and melt extraction within the partially molten regions beneath ocean ridges. Fig 1. Melt channels in an olivine-basalt sample with 10 vol% melt.

[Characteristics of mercury exchange flux between soil and atmosphere under the snow retention and snow melting control].

PubMed

Zhang, Gang; Wang, Ning; Ai, Jian-Chao; Zhang, Lei; Yang, Jing; Liu, Zi-Qi

2013-02-01

Jiapigou gold mine, located in the upper Songhua River, was once the largest mine in China due to gold output, where gold extraction with algamation was widely applied to extract gold resulting in severe mercury pollution to ambient environmental medium. In order to study the characteristics of mercury exchange flux between soil (snow) and atmosphere under the snow retention and snow melting control, sampling sites were selected in equal distances along the slope which is situated in the typical hill-valley terrain unit. Mercury exchange flux between soil (snow) and atmosphere was determined with the method of dynamic flux chamber and in all sampling sites the atmosphere concentration from 0 to 150 cm near to the earth in the vertical direction was measured. Furthermore, the impact factors including synchronous meteorology, the surface characteristics under the snow retention and snow melting control and the mercury concentration in vertical direction were also investigated. The results are as follows: During the period of snow retention and melting the air mercury tends to gather towards valley bottom along the slope and an obvious deposit tendency process was found from air to the earth's surface under the control of thermal inversion due to the underlying surface of cold source (snow surface). However, during the period of snow melting, mercury exchange flux between the soil and atmosphere on the surface of the earth with the snow being melted demonstrates alternative deposit and release processes. As for the earth with snow covered, the deposit level of mercury exchange flux between soil and atmosphere is lower than that during the period of snow retention. The relationship between mercury exchange flux and impact factors shows that in snow retention there is a remarkable negative linear correlation between mercury exchange flux and air mercury concentration as well as between the former and the air temperature. In addition, in snow melting mercury exchange flux is remarkably negatively linearly correlated to air mercury concentration and positively linearly correlated to air temperature. Furthermore, there is a general positive linear correlation between mercury exchange flux and soil temperature on the surface of earth after snow melting.

Influence of heat-piping on the initiation and evolution of plate tectonics

NASA Astrophysics Data System (ADS)

Tosi, N.; Baumeister, P. A.

2017-12-01

The onset of plate tectonics on Earth is believed to be caused by local weakening of the lithosphere. If the convective stress locally exceeds a critical value, a plate-breaking event may occur and initiate plate tectonics. Heat-piping is a heat transport process in which a large amount of melt produced at depth migrates either to the surface (extrusive volcanism) or the base of the crust and lithosphere (intrusive volcanism) due to positive buoyancy and over-pressure in the melting region. As a result of melt being extruded and compacted at the surface or within the crust and lithosphere, cold, near surface material is advected downwards. This mechanism, which effectively cools the mantle, has been proposed to dominate the early phases of the Earth's evolution preventing the onset of plate tectonics by leveling the slope of the lithosphere (e.g. Moore & Webb, 2013, Kankanamge & Moore, 2016). This in turn prevents the formation of lithospheric undulations that are necessary to locally build up sufficient stress to initiate a plate-breaking event. In this work we explore the effects of both extrusive and intrusive heat-piping on the critical yield stress needed to start a plate-breaking event and maintain a regime of surface mobilization over long timescales. We use a two-dimensional cylindrical model of compressible thermal convection. The melt generated at depth is extracted instantaneously according to a defined ratio between extrusive and intrusive volcanism. Extrusive melt is deposited at the surface, whereas intrusive melt is assumed to migrate to a depth dependent on the pressure distribution in the column above the melt region. Considering heat piping tends to increase the episodicity in the mobilization of the surface due to the additional local cooling caused by melt extraction but does not affect significantly the critical yield stress necessary to induce lid failure. Our models indicate that the evolution of plate mobility is a stochastic process, strongly dependent on the choice of the initial conditions. Heat-piping does not seem to be a controlling factor for the onset of plate tectonics.

Transfer Rates of Magma From Planetary Mantles to the Surface.

NASA Astrophysics Data System (ADS)

Wilson, L.; Head, J. W.; Parfitt, E. A.

2008-12-01

We discuss the speed at which magma can be transferred to a planetary surface from the deep interior. Current literature describes a combination of slow percolation of melt in the mantle where convection-driven pressure-release melting is occurring, concentration of melt by source region deformation, initiation and growth of magma-filled brittle fractures (dikes) providing wider pathways for melt movement, additional growth and interconnection of dikes with decreasing depth, rise of magma to storage zones (reservoirs) located at levels of neutral buoyancy at the base of or within the crust, and transfer from the storage zones in dikes to feed eruptions or intrusions. We do not take issue with these mechanisms but think that their relative importance in various circumstances is poorly appreciated. On Earth, preservation of diamonds in kimberlites implies very rapid (hours) transfer of melts from depths of 100-300 km, and there is strong geochemical evidence that magmas at mid-ocean ridges reach shallow depths faster than is possible by percolation alone. On the Moon, the petrology of pyroclasts involved in dark-mantle-forming eruptions implies rapid (again probably hours) magma transfer from depths of up to 400 km. The ureilite meteorites, samples of the mantle of a disrupted asteroid 200 km in diameter, have compositions only consistent with the rapid (months) extraction of mafic melt from the mantle. All of these examples imply that brittle fractures (dikes) can sometimes be initiated at depths where mantle rheology would normally be expected to be plastic rather than elastic, and that melt can be fed into these dikes extremely efficiently. Further evidence for this is provided by the giant radial dike swarms observed on Earth, Mars and Venus. The dikes observed (on Earth) and inferred from the presence of radiating graben systems (Mars) and radiating fracture and graben systems (Venus) are so voluminous that they can only be understood if they are fed from extremely large magma reservoirs, probably located at the base of the crust, that are supplied from the mantle (i.e. buffered) while the dikes are being emplaced, again implying extremely efficient melt extraction from mantle source regions.

Hydrophilic magnetic ionic liquid for magnetic headspace single-drop microextraction of chlorobenzenes prior to thermal desorption-gas chromatography-mass spectrometry.

PubMed

Fernández, Elena; Vidal, Lorena; Canals, Antonio

2017-11-23

A new, fast, easy to handle, and environmentally friendly magnetic headspace single-drop microextraction (Mag-HS-SDME) based on a magnetic ionic liquid (MIL) as an extractant solvent is presented. A small drop of the MIL 1-ethyl-3-methylimidazolium tetraisothiocyanatocobaltate(II) ([Emim] 2 [Co(NCS) 4 ]) is located on one end of a small neodymium magnet to extract nine chlorobenzenes (1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, 1,2,3,4-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, and pentachlorobenzene) as model analytes from water samples prior to thermal desorption-gas chromatography-mass spectrometry determination. A multivariate optimization strategy was employed to optimize experimental parameters affecting Mag-HS-SDME. The method was evaluated under optimized extraction conditions (i.e., sample volume, 20 mL; MIL volume, 1 μL; extraction time, 10 min; stirring speed, 1500 rpm; and ionic strength, 15% NaCl (w/v)), obtaining a linear response from 0.05 to 5 μg L -1 for all analytes. The repeatability of the proposed method was evaluated at 0.7 and 3 μg L -1 spiking levels and coefficients of variation ranged between 3 and 18% (n = 3). Limits of detection were in the order of nanograms per liter ranging from 4 ng L -1 for 1,4-dichlorobenzene and 1,2,3,4-tetrachlorobenzene to 8 ng L -1 for 1,2,4,5-tetrachlorobenzene. Finally, tap water, pond water, and wastewater were selected as real water samples to assess the applicability of the method. Relative recoveries varied between 82 and 114% showing negligible matrix effects. Graphical abstract Magnetic headspace single-drop microextraction followed by thermal desorption-gas chromatography-mass spectrometry.

Highly Siderophile Elements as Tracers for the Subcontinental Mantle Evolution Beneath the Southwestern USA: The San Carlos and Kilbourne Hole Peridotite Xenoliths Revisited

NASA Technical Reports Server (NTRS)

vanAcken, D.; Brandon, A. D.; Peslier, A. H.; Lee, C.-T. A.

2010-01-01

Peridotite xenoliths from San Carlos, Arizona, and Kilbourne Hole, New Mexico, have been studied since the 1970 s to give insights into melting and metasomatism in the subcontinental mantle beneath the southwestern USA. More recently, the highly siderophile elements (HSE; Os, Ir, Ru, Rh, Pt, Pd, and Re) and the included Re-Os isotope system have been established as powerful tools for the study of mantle processes because of their range in compatibility during mantle melting and their siderophile and chalcophile geochemical behavior. Model aluminachron Re-Os ages for San Carlos and Kilbourne Hole, as well as for the nearby Dish Hill and Vulcan's Throne sites, give consistent depletion ages of around 2.2 Ga. This age can be interpreted as a single large scale mantle melting event linked to crustal formation and continental growth under the southwestern USA. Highly siderophile elements, however, may be added to depleted peridotites via melt-rock interaction, especially the more incompatible and hence mobile Pt, Pd, and Re. This may result in overprinting of the signature of melt extraction, thus abating the usefulness of Re-Os mantle extraction model ages. A comprehensive characterization of the suite of mantle xenoliths from the SW USA in terms of HSE concentrations is thus necessary to re-assess the Re-Os system for dating purposes. San Carlos peridotites are depleted to moderately fertile, as indicated by their bulk Al2O3 contents between 0.66 wt% and 3.13 wt%. Bulk Os-187/Os-188 in San Carlos peridotites range from 0.1206 to 0.1357. In contrast, Kilbourne Hole peridotites tend to be more fertile with Al2O3 between 2.11 and 3.78 wt%, excluding one extremely depleted sample with 0.30 wt% Al2O3, and have Os-187/Os-188 between 0.1156 and 0.1272, typical for mantle peridotites. No large fractionation between the more compatible HSE Os, Ir, and Ru are observed. The more incompatible HSE Re, Pd, and to a minor extent, Pt, however, are depleted in a number of samples by factors of up to 4 for Pt, 6 for Pd, and 20 for Re, compared to primitive mantle estimates. This is in agreement with previous studies from the same locales, which demonstrated the presence of different populations of mantle xenoliths having undergone various degrees of melt extraction. The depletion of the more incompatible elements (Re, Pd, and Pt) also suggests that the HSE budgets of the SW USA peridotites were primarily established by extraction of basaltic melt, and reflect only minor influence from later episodes of metasomatism. Model Re-Os ages obtained from San Carlos and Kilbourne Hole xenoliths may thus reflect ages of crustal formation and mantle depletion in the SW USA region.

Evidence for chemically heterogeneous Arctic mantle beneath the Gakkel Ridge

NASA Astrophysics Data System (ADS)

D'Errico, Megan E.; Warren, Jessica M.; Godard, Marguerite

2016-02-01

Ultraslow spreading at mid-ocean ridges limits melting due to on-axis conductive cooling, leading to the prediction that peridotites from these ridges are relatively fertile. To test this, we examined abyssal peridotites from the Gakkel Ridge, the slowest spreading ridge in the global ocean ridge system. Major and trace element concentrations in pyroxene and olivine minerals are reported for 14 dredged abyssal peridotite samples from the Sparsely Magmatic (SMZ) and Eastern Volcanic (EVZ) Zones. We observe large compositional variations among peridotites from the same dredge and among dredges in close proximity to each other. Modeling of lherzolite trace element compositions indicates varying degrees of non-modal fractional mantle melting, whereas most harzburgite samples require open-system melting involving interaction with a percolating melt. All peridotite chemistry suggests significant melting that would generate a thick crust, which is inconsistent with geophysical observations at Gakkel Ridge. The refractory harzburgites and thin overlying oceanic crust are best explained by low present-day melting of a previously melted heterogeneous mantle. Observed peridotite compositional variations and evidence for melt infiltration demonstrates that fertile mantle components are present and co-existing with infertile mantle components. Melt generated in the Gakkel mantle becomes trapped on short length-scales, which produces selective enrichments in very incompatible rare earth elements. Melt migration and extraction may be significantly controlled by the thick lithosphere induced by cooling at such slow spreading rates. We propose the heterogeneous mantle that exists beneath Gakkel Ridge is the consequence of ancient melting, combined with subsequent melt percolation and entrapment.

Materials Research Society Symposium Proceedings, Volume 758 Held in Boston, Massachusetts on December 3-5, 2002. Rapid Prototyping Technologies

DTIC Science & Technology

2003-04-01

lithography to associate curved and conical structures with the smooth and vertical walls and micrometer accuracy of SU-8 technology [24]. It has been...Sintering (SLS) -3D O Stereolithography (SLA) - 3D Systems Systems Curing with Visible Light and DMD Melting with Lasers 0 Direct Photo Shaping (DPS...LAM) - AeroMet Electrolyte 0 Direct Metal Dep. ( DMD ) - POM Electroplating * Electrochemical Fab. (EFAB) - USC BINDER-based Drop Binding Powder Printing

Fundamentals of rapid solidification processing

NASA Technical Reports Server (NTRS)

Flemings, Merton C.; Shiohara, Yuh

1985-01-01

An attempt is made to illustrate the continuous change that occurs in the solidification behavior of undercooled melts, as cooling rates increase from 0.0001 K/sec to about 1000 K/sec. At the higher cooling rates, more significant changes occur as the dendrite tip temperature begins to drop from the equilibrium liquidus. Discontinuous solidification behavior changes will occur if absolute stability is reached, or a metastable phase forms, or solidification proceeds to a glass rather than to a crystalline solid, or if there is significant undercooling prior to nucleation.

Fluid-Solid Interaction and Multiscale Dynamic Processes: Experimental Approach

NASA Astrophysics Data System (ADS)

Arciniega-Ceballos, Alejandra; Spina, Laura; Mendo-Pérez, Gerardo M.; Guzmán-Vázquez, Enrique; Scheu, Bettina; Sánchez-Sesma, Francisco J.; Dingwell, Donald B.

2017-04-01

The speed and the style of a pressure drop in fluid-filled conduits determines the dynamics of multiscale processes and the elastic interaction between the fluid and the confining solid. To observe this dynamics we performed experiments using fluid-filled transparent tubes (15-50 cm long, 2-4 cm diameter and 0.3-1 cm thickness) instrumented with high-dynamic piezoelectric sensors and filmed the evolution of these processes with a high speed camera. We analyzed the response of Newtonian fluids to slow and sudden pressure drops from 3 bar-10 MPa to ambient pressure. We used fluids with viscosities of mafic to intermediate silicate melts of 1 to 1000 Pa s and water. The processes observed are fluid mass expansion, fluid flow, jets, bubbles nucleation, growth, coalescence and collapse, degassing, foam building at the surface and vertical wagging. All these processes (in fine and coarse scales) are triggered by the pressure drop and are sequentially coupled in time while interacting with the solid. During slow decompression, the multiscale processes are recognized occurring within specific pressure intervals, and exhibit a localized distribution along the conduit. In this, degassing predominates near the surface and may present piston-like oscillations. In contrast, during sudden decompression the fluid-flow reaches higher velocities, the dynamics is dominated by a sequence of gas-packet pulses driving jets of the gas-fluid mixture. The evolution of this multiscale phenomenon generates complex non-stationary microseismic signals recorded along the conduit. We discuss distinctive characteristics of these signals depending on the decompression style and compare them with synthetics. These synthetics are obtained numerically under an averaging modeling scheme, that accounted for the stress-strain of the cyclic dynamic interaction between the fluid and the solid wall, assuming an incompressible and viscous fluid that flows while the elastic solid responds oscillating. Analysis of time series, both experimental and synthetics, synchronized with high-speed imaging enables the explanation and interpretation of distinct phases of the dynamics of these fluids and the extraction of time and frequency characteristics of the individual processes. We observed that the effects of both, pressure drop triggering function and viscosity, control the characteristics of the micro-signals in time and frequency. This suggests the great potential that experimental and numerical approaches provide to untangle from field volcanic seismograms the multiscale processes of the stress field, driving forces and fluid-rock interaction that determine the volcanic conduit dynamics.

Experimental Observations of Multiscale Dynamics of Viscous Fluid Behavior: Implications in Volcanic Systems

NASA Astrophysics Data System (ADS)

Arciniega-Ceballos, A.; Spina, L.; Scheu, B.; Dingwell, D. B.

2015-12-01

We have investigated the dynamics of Newtonian fluids with viscosities (10-1000 Pa s; corresponding to mafic to intermediate silicate melts) during slow decompression, in a Plexiglas shock tube. As an analogue fluid we used silicon oil saturated with Argon gas for 72 hours. Slow decompression, dropping from 10 MPa to ambient pressure, acts as the excitation mechanism, initiating several processes with their own distinct timescales. The evolution of this multi-timescale phenomenon generates complex non-stationary microseismic signals, which have been recorded with 7 high-dynamic piezoelectric sensors located along the conduit. Correlation analysis of these time series with the associated high-speed imaging enables characterization of distinct phases of the dynamics of these viscous fluids and the extraction of the time and the frequency characteristics of the individual processes. We have identified fluid-solid elastic interaction, degassing, fluid mass expansion and flow, bubble nucleation, growth, coalescence and collapse, foam building and vertical wagging. All these processes (in fine and coarse scales) are sequentially coupled in time, occur within specific pressure intervals, and exhibit a localized distribution in space. Their coexistence and interactions constitute the stress field and driving forces that determine the dynamics of the system. Our observations point to the great potential of this experimental approach in the understanding of volcanic processes and volcanic seismicity.

Total sulfur dioxide emissions and pre-eruption vapor-saturated magma at Mount St. Helens, 1980-88

NASA Astrophysics Data System (ADS)

Gerlach, T. M.; McGee, K. A.

1994-12-01

SO2 from explosive volcanism can cause significant climatic and atmospheric impacts, but the source of the sulfur is controversial. Total ozone mapping spectrometer (TOMS), correlation spectrometer (COSPEC), and ash leachate data for Mount St. Helens from the time of the climactic eruption on 18 May 1980 to the final stages of non-explosive degassing in 1988 give a total SO2 emission of 2 Mt. COSPEC data show a sharp drop in emission rate that was apparently controlled by a decreasing rate of magma supply. A total SO2 emission of only 0.08 Mt is estimated from melt inclusion data and the conventional assumption that the main sulfur source was pre-eruption melt; commonly invoked sources of 'excess sulfur' (anhydrite decomposition, basaltic magma, and degassing of non-erupted magma) are unlikely in this case. Thus melt inclusions may significantly underestimate SO2 emissions and impacts of explosive volcanism on climate and the atmosphere. Measured CO2 emissions, together with the H2O content of melt inclusions and experimental solubility data, indicate the Mount St. Helens dacite was vapor-saturated at depth prior to ascent and suggest that a vapor phase was the main source of sulfur for the 2-Mt of SO2. A vapor source is consistent with experimental studies on the Mount St. Helens dacite and removes the need for a much debated shallow magma body.

Magma Plumbing System at a Young Back-Arc Spreading Center: The Marsili Volcano, Southern Tyrrhenian Sea

NASA Astrophysics Data System (ADS)

Trua, T.; Marani, M. P.; Gamberi, F.

2018-01-01

Although spreading rate is commonly taken as a proxy for decompression mantle melting at mid-ocean ridges (MORs), magmatism at back-arc spreading centers (BASCs) is further influenced by the subduction-related flux melting of the mantle. These regions consequently show a diversity of crustal structures, lava compositions, and morphologies not typically found in MORs. Here we investigate the crustal plumbing system of the small-scale, Marsili back-arc spreading center of the Southern Tyrrhenian Sea using plagioclase data from a wide spectrum of lavas (basalts to andesites) dredged from its summit and flanks. We employ petrological modeling to identify the plagioclase populations carried in the individual lavas, allocate them to plausible magmatic components present within the plumbing system, and trace the processes occurring during magma ascent to the surface. The properties of the system, such as mush porosity and abundance of the melt bodies, vary from one magma extraction zone to another along the BASC, evidencing the local variability of melt supply conditions. The plagioclase crystals document a range of relationships with the host lavas, indicating magma extraction from a composite, vertically extensive mush and melt-lens system resembling that of MORs. At the same time, however, in small BASCs, such as in the case of the Marsili Basin, crustal accretion and resulting morphology are significantly influenced by the three-dimensional setting of the basin margins. This is an important deviation from the conventional model based on the linear continuity and essentially two-dimensional framework of MORs.

Simultaneous extraction and quantification of lamotrigine, phenobarbital, and phenytoin in human plasma and urine samples using solidified floating organic drop microextraction and high-performance liquid chromatography.

PubMed

Asadi, Mohammad; Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad; Abbasi, Bijan

2015-07-01

A novel and simple method based on solidified floating organic drop microextraction followed by high-performance liquid chromatography with ultraviolet detection has been developed for simultaneous preconcentration and determination of phenobarbital, lamotrigine, and phenytoin in human plasma and urine samples. Factors affecting microextraction efficiency such as the type and volume of the extraction solvent, sample pH, extraction time, stirring rate, extraction temperature, ionic strength, and sample volume were optimized. Under the optimum conditions (i.e. extraction solvent, 1-undecanol (40 μL); sample pH, 8.0; temperature, 25°C; stirring rate, 500 rpm; sample volume, 7 mL; potassium chloride concentration, 5% and extraction time, 50 min), the limits of detection for phenobarbital, lamotrigine, and phenytoin were 1.0, 0.1, and 0.3 μg/L, respectively. Also, the calibration curves for phenobarbital, lamotrigine, and phenytoin were linear in the concentration range of 2.0-300.0, 0.3-200.0, and 1.0-200.0 μg/L, respectively. The relative standard deviations for six replicate extractions and determinations of phenobarbital, lamotrigine, and phenytoin at 50 μg/L level were less than 4.6%. The method was successfully applied to determine phenobarbital, lamotrigine, and phenytoin in plasma and urine samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Partial melting kinetics of plagioclase-diopside pairs

NASA Astrophysics Data System (ADS)

Tsuchiyama, Akira

1985-09-01

Partial melting experiments on plagioclase (An60) and diopside have been carried out using pairs of large crystals to investigate textures and kinetics of melting. The experiments were done at one atmosphere pressure as a function of temperature (1,190 1,307° C) and time (1.5 192 h). Melting took place mainly at the plagioclase-diopside contact planes. Reaction zones composed of fine mixtures of calcic plagioclase and melt were developed from the surface of the plagioclase crystal inward. There exists a critical temperature, below which only a few % melting can occur over the duration of the experiments. This sluggish melting is caused by slow NaSi-CaAl diffusion in plagioclase, because the plagioclase crystal must change its composition to produce albite-rich cotectic melts. Diffusion in the solid also affects the chemical composition of the melts. During initial melting, potassium is preferentially extracted from plagioclase because K-Na diffusion in plagioclase is faster than that of NaSi-CaAl. This also causes a shift in the cotectic compositions. Above the “critical temperature”, on the other hand, melting is promoted by a metastable reaction in which the plagioclase composition does not change, and which produces melts with compositional gradients along the original An60-diopside tie line. The critical temperature is determined by the intersection of the cotectic and the An60-diopside tie line. Interdiffusion coefficients of plagioclase-diopside components in the melt are estimated from melting rates above the critical temperature by using a simplified steady-state diffusion model (e.g., 10-8 cm2/sec at 1,300° C). Many examples of reaction zones due to partial melting have been described as spongy or fingerprint-like textures in xenoliths. Metastable melting above the critical temperature is considered to take place in natural melting where there is a high degree of melting. However, we cannot exclude the possibility of disequilibrium created by sluggish melting controlled by diffusion in the minerals. If melting occurs close to the solidus, this process can be important even for partial melting in the upper mantle.

Generation of trondhjemite from partial melting of dacite under granulite facies conditions: an example from the New Jersey Highlands, USA

USGS Publications Warehouse

Puffer, J.H.; Volkert, R.A.

1991-01-01

New field and geochemical data place the Losee Metamorphic Suite (a tonalite/trondhjemite complex) of northern New Jersey into the context of a major Proterozoic continental are represented by a discontinuous belt of northern Appalachian metadacite. Samples of Losee rock range from extremely leucocratic trondhjemite locally associated with amphibolite, to banded biotite, hornblende, pyroxene, and garnet-bearing tonalites. The major element and REE composition of the tonalite closely resembles dacite from continental are settings and model melts extracted from an eclogite residue by partial melting at 15 kbar. The REE composition of most Losee trondhjemite is enriched in REE, particularly HREE, compared with Losee tonalite, and is interpreted as the product of local anatectic melting of Losee tonalite (metadacite) that occurred in a granulite facies environment during the Grenville orogeny. ?? 1991.

Hot-wire Laser Welding of Deep and Wide Gaps

NASA Astrophysics Data System (ADS)

Näsström, J.; Frostevarg, J.; Silver, T.

Heavy section Gas Metal Arc Welding (GMAW) usually requires special edge preparation and several passes. One alternative for increased performance is Laser Arc Hybrid Welding (LAHW). For very thick sheets however, imperfections like root drops or solidification cracks can occur. In this study, other techniques are also studied, including multi-pass filling of deep gaps with wire deposition. A laser is then used to melt the filler and base material. The hot- and cold wire laser welding processes are highly sensitive to wire-laser positioning, where controlled melting of the wire is essential. Apart from a comprehensive literature survey, preliminary experiments were also performed in order to find a novel method variant that can successfully fill deep and wide gaps. The method applied uses a defocused laser that generates the melt pool. A resistance heated wire is fed into the melt pool front in a leading position. This is similar to additive manufacturing techniques such as laser direct metal deposition with wire. A layer height of several millimeters can be achieved and rather low laser power can be chosen. The preliminary experiments were observed using high speed imaging and briefly evaluated by visual examination of the resulting beads. Using a defocused laser beam turned out to have two major advantages; 1. It adds heat to the melt pool in a manner that properly fuses the bottom and walls of the base material. 2. It counteracts difficulties due to an irregularly oscillating filler wire. These early results show that this can be a promising technique for joining thick steels with wide gaps.

A comparison of acoustic levitation with microgravity processing for containerless solidification of ternary Al-Cu-Sn alloy

NASA Astrophysics Data System (ADS)

Yan, N.; Hong, Z. Y.; Geng, D. L.; Wei, B.

2015-07-01

The containerless rapid solidification of liquid ternary Al-5 %Cu-65 %Sn immiscible alloy was accomplished at both ultrasonic levitation and free fall conditions. A maximum undercooling of 185 K (0.22 T L) was obtained for the ultrasonically levitated alloy melt at a cooling rate of about 122 K s-1. Meanwhile, the cooling rate of alloy droplets in drop tube varied from 102 to 104 K s-1. The macrosegregation was effectively suppressed through the complex melt flow under ultrasonic levitation condition. In contrast, macrosegregation became conspicuous and core-shell structures with different layers were formed during free fall. The microstructure formation mechanisms during rapid solidification at containerless states were investigated in comparison with the conventional static solidification process. It was found that the liquid phase separation and structural growth kinetics may be modulated by controlling both alloy undercooling and cooling rate.

The role of water in the petrogenesis of Marina trough magmas

NASA Astrophysics Data System (ADS)

Stolper, Edward; Newman, Sally

1994-02-01

Most variations in composition among primitive basalts from the Mariana back-arc trough can be explained by melting mixtures of an N-type mid-ocean ridge basalt (NMORB) mantle source and an H2O rich component, provided the degree of melting is positively and approximately linearly correlated with the proportion of the H2O-rich component in the mixture. We conclude that the degrees of melting by which Mariana trough magmas are generated increase from magmas similar to NMORB, through more H2O-enriched basalts, to 'arc-like' basalts, and that this increase is due to the lowering of the solidus of mantle peridotite that accompanies addition of the H2O-rich component. The H2O-rich component is likely to be ultimately derived from fluid from a subducting slab, but we propose that by the time fluids reach the source regions of Mariana trough basalts, they have interacted with sufficient mantle material that for all but the most incompatible of elements (with respect to fluid-mantle interaction), they are in equilibrium with the mantle. In contrast, fluids added to the source regions of Mariana island-arc magmas have typically interacted with less mantle and thus retain the signature of slab-derived fluids to varying degrees for all but the most compatible elements. Primitive Mariana arc basalts can be generated by melting mixtures of such incompletely exchanged slab-derived fluids and sources similar to NMORB-type mantle sources, but the degrees of melting are typically higher than those of Mariana trough NMORB and the sources have been variably depleted relative to the back-arc sources by previous melt extraction. This depletion may be related to earlier extraction of back-arc basin magmas or may evolve by repeated fluxing of the sources as fluid is continually added to them in the regions of arc magma generation. If fluid with partitioning behavior relative to the solid mantle similar to that deduced for the H2O-rich component involved in the generation of Mariana trough basalts were extracted from primitive mantle, the residual mantle would have many of the minor and trace element characteristics of typical oceanic upper mantle; primitive mantle enriched in such fluid would be a satisfactory source for the continental crust in terms of its trace and minor element chemical composition.

Petrological Geodynamics of Mantle Melting II. AlphaMELTS + Multiphase Flow: Dynamic Fractional Melting

NASA Astrophysics Data System (ADS)

Tirone, Massimiliano

2018-03-01

In this second installment of a series that aims to investigate the dynamic interaction between the composition and abundance of the solid mantle and its melt products, the classic interpretation of fractional melting is extended to account for the dynamic nature of the process. A multiphase numerical flow model is coupled with the program AlphaMELTS, which provides at the moment possibly the most accurate petrological description of melting based on thermodynamic principles. The conceptual idea of this study is based on a description of the melting process taking place along a 1-D vertical ideal column where chemical equilibrium is assumed to apply in two local sub-systems separately on some spatial and temporal scale. The solid mantle belongs to a local sub-system (ss1) that does not interact chemically with the melt reservoir which forms a second sub-system (ss2). The local melt products are transferred in the melt sub-system ss2 where the melt phase eventually can also crystallize into a different solid assemblage and will evolve dynamically. The main difference with the usual interpretation of fractional melting is that melt is not arbitrarily and instantaneously extracted from the mantle, but instead remains a dynamic component of the model, hence the process is named dynamic fractional melting (DFM). Some of the conditions that may affect the DFM model are investigated in this study, in particular the effect of temperature, mantle velocity at the boundary of the mantle column. A comparison is made with the dynamic equilibrium melting (DEM) model discussed in the first installment. The implications of assuming passive flow or active flow are also considered to some extent. Complete data files of most of the DFM simulations, four animations and two new DEM simulations (passive/active flow) are available following the instructions in the supplementary material.

A novel method of measuring the melting point of animal fats.

PubMed

Lloyd, S S; Dawkins, S T; Dawkins, R L

2014-10-01

The melting point (TM) of fat is relevant to health, but available methods of determining TM are cumbersome. One of the standard methods of measuring TM for animal and vegetable fats is the slip point, also known as the open capillary method. This method is imprecise and not amenable to automation or mass testing. We have developed a technique for measuring TM of animal fat using the Rotor-Gene Q (Qiagen, Hilden, Germany). The assay has an intra-assay SD of 0.08°C. A single operator can extract and assay up to 250 samples of animal fat in 24 h, including the time to extract the fat from the adipose tissue. This technique will improve the quality of research into genetic and environmental contributions to fat composition of meat.

Formation of curved micrometer-sized single crystals.

PubMed

Koifman Khristosov, Maria; Kabalah-Amitai, Lee; Burghammer, Manfred; Katsman, Alex; Pokroy, Boaz

2014-05-27

Crystals in nature often demonstrate curved morphologies rather than classical faceted surfaces. Inspired by biogenic curved single crystals, we demonstrate that gold single crystals exhibiting curved surfaces can be grown with no need of any fabrication steps. These single crystals grow from the confined volume of a droplet of a eutectic composition melt that forms via the dewetting of nanometric thin films. We can control their curvature by controlling the environment in which the process is carried out, including several parameters, such as the contact angle and the curvature of the drops, by changing the surface tension of the liquid drop during crystal growth. Here we present an energetic model that explains this phenomenon and predicts why and under what conditions crystals will be forced to grow with the curvature of the microdroplet even though the energetic state of a curved single crystal is very high.

Method to produce large, uniform hollow spherical shells

DOEpatents

Hendricks, C.D.

1983-09-26

The invention is a method to produce large uniform hollow spherical shells by (1) forming uniform size drops of heat decomposable or vaporizable material, (2) evaporating the drops to form dried particles, (3) coating the dried particles with a layer of shell forming material and (4) heating the composite particles to melt the outer layer and to decompose or vaporize the inner particle to form an expanding inner gas bubble. The expanding gas bubble forms the molten outer layer into a shell of relatively large diameter. By cycling the temperature and pressure on the molten shell, nonuniformities in wall thickness can be reduced. The method of the invention is utilized to produce large uniform spherical shells, in the millimeter to centimeter diameter size range, from a variety of materials and of high quality, including sphericity, concentricity and surface smoothness, for use as laser fusion or other inertial confinement fusion targets as well as other applications.

On the constitutive description of the microinteractions concept in steam explosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, X.; Yuen, W.W.; Theofanous, T.G.

This paper elaborates on the constitutive description of the {open_quotes}microinteraction{close_quotes} model used by the computer code ESPROSE.m to simulate the propagation phase of steam explosions. The approach is based on a series of experiments, in the SIGMA-2000 facility, involving molten drops of tin made to explode under sustained pressure fields; an environment similar to that of a fully-developed large-scale detonation. The experimental ranges cover shock pressures of up to 204 bar, melt temperatures of up to 1800{degrees}C, and series of isothermal runs, using gallium drops, are also included. The results indicate that, to a first approximation, the basic form ofmore » the constitutive laws hypothesized in the original formulation of ESPROSE.m is appropriate. Moreover, through detailed comparison of data with numerical experiments, certain parameters appearing in these laws could be identified quantitatively.« less

Wetting and Spreading of Molten Volcanic Ash in Jet Engines.

PubMed

Song, Wenjia; Lavallée, Yan; Wadsworth, Fabian B; Hess, Kai-Uwe; Dingwell, Donald B

2017-04-20

A major hazard to jet engines posed by volcanic ash is linked to the wetting and spreading of molten ash droplets on engine component surfaces. Here, using the sessile drop method, we study the evolution of the wettability and spreading of volcanic ash. We employ rapid temperature changes up to 1040-1450 °C, to replicate the heating conditions experienced by volcanic ash entering an operating jet engine. In this scenario, samples densify as particles coalesce under surface tension until they form a large system-sized droplet (containing remnant gas bubbles and crystals), which subsequently spreads on the surface. The data exhibit a transition from a heterogeneous to a homogeneous wetting regime above 1315 °C as crystals in the drops are dissolved in the melt. We infer that both viscosity and microstructural evolution are key controls on the attainment of equilibrium in the wetting of molten volcanic ash droplets.

NASA MSFC Electrostatic Levitator (ESL) Rapid Quench System

NASA Technical Reports Server (NTRS)

SanSoucie, Michael P.; Craven, Paul D.

2014-01-01

Electrostatic levitation, a form of containerless processing, is an important tool in materials research. Levitated specimens are free from contact with a container; therefore, heterogeneous nucleation on container walls is not possible. This allows studies of deeply undercooled melts. Furthermore, studies of high-temperature, highly reactive materials are also possible. Studies of the solidification and crystallization of undercooled melts is vital to the understanding of microstructure development, particularly the formation of alloys with unique properties by rapid solidification. The NASA Marshall Space Flight Center (MSFC) Electrostatic Levitator (ESL) lab has recently been upgraded to allow for rapid quenching of levitated materials. The ESL Rapid Quench System uses a small crucible-like vessel that can be partially filled with a low melting point material, such as a Gallium alloy, as a quench medium. An undercooled sample can be dropped into the vessel to rapidly quench the sample. A carousel with nine vessels sits below the bottom electrode assembly. This system allows up to nine rapid quenches before having to break vacuum and remove the vessels. This new Rapid Quench System will allow materials science studies of undercooled materials and new materials development. In this presentation, the system is described and initial results are presented.

DSD Characteristics of a Mid-Winter Tornadic Storm Using C-Band Polarimetric Radar and Two 2D-Video Disdrometers

NASA Technical Reports Server (NTRS)

Thurai, M.; Petersen, W. A.; Carey, L. A.

2010-01-01

Drop size distributions in an evolving tornadic storm are examined using C-band polarimetric radar observations and two 2D-video disdrometers. The E-F2 storm occurred in mid-winter (21 January 2010) in northern Alabama, USA, and caused widespread damage. The evolution of the storm occurred within the C-band radar coverage and moreover, several minutes prior to touch down, the storm passed over a site where several disdrometers including two 2D video disdrometers (2DVD) had been installed. One of the 2DVDs is a low profile unit and the other is a new next generation compact unit currently undergoing performance evaluation. Analyses of the radar data indicate that the main region of precipitation should be treated as a "big-drop" regime case. Even the measured differential reflectivity values (i.e. without attenuation correction) were as high as 6-7 dB within regions of high reflectivity. Standard attenuation-correction methods using differential propagation phase have been "fine tuned" to be applicable to the "big drop" regime. The corrected reflectivity and differential reflectivity data are combined with the co-polar correlation coefficient and specific differential phase to determine the mass-weighted mean diameter, Dm, and the width of the mass spectrum, (sigma)M, as well as the intercept parameter , Nw. Significant areas of high Dm (3-4 mm) were retrieved within the main precipitation areas of the tornadic storm. The "big drop" regime assumption is substantiated by the two sets of 2DVD measurements. The Dm values calculated from 1-minute drop size distributions reached nearly 4 mm, whilst the maximum drop diameters were over 6 mm. The fall velocity measurements from the 2DVD indicate almost all hydrometeors to be fully melted at ground level. Drop shapes for this event are also being investigated from the 2DVD camera data.

Extraction of trace metals from fly ash

DOEpatents

Blander, M.; Wai, C.M.; Nagy, Z.

1983-08-15

A process is described for recovering silver, gallium and/or other trace metals from a fine grained industrial fly ash associated with a process for producing phosphorous. The fly ash has a silicate base and contains surface deposits of the trace metals as oxides, chlorides or the like. The process is carried out by contacting the fly ash with AlCl/sub 3/ in an alkali halide melt to react the trace metals with the AlCl/sub 3/ to form compositions soluble in the melt and a residue containing the silicate and aluminum oxide or other aluminum precipitate, and separating the desired trace metal or metals from the melt by electrolysis or other separation techniques.

Extraction of trace metals from fly ash

DOEpatents

Blander, Milton; Wai, Chien M.; Nagy, Zoltan

1984-01-01

A process for recovering silver, gallium and/or other trace metals from a fine grained industrial fly ash associated with a process for producing phosphorous, the fly ash having a silicate base and containing surface deposits of the trace metals as oxides, chlorides or the like, with the process being carried out by contacting the fly ash with AlCl.sub.3 in an alkali halide melt to react the trace metals with the AlCl.sub.3 to form compositions soluble in the melt and a residue containing the silicate and aluminum oxide or other aluminum precipitate, and separating the desired trace metal or metals from the melt by electrolysis or other separation techniques.

Geochemical constraints on crustal anatexis: a case study from the Pan-African Damara granitoids of Namibia

NASA Astrophysics Data System (ADS)

McDermott, F.; Harris, N. B. W.; Hawkesworth, C. J.

1996-05-01

Major and trace element models of recently published vapour-absent mica dehydration melting experiments are used to identify granitoids generated by muscovite and biotite dehydration melting, and to distinguish between plagioclase-limited and biotite-limited, biotite dehydration melting. In the case of granitoids from the Pan-African Damara mobile belt (Namibia), many of the leucogranites and Salem-type granitoids may be modelled by biotite dehydration melting. The low Rb/Sr granitoids (e.g. Donkerhuk Onanis, Salem Onanis, Donkerhuk Nomatsaus, Salem Goas) probably reflect feldspar-limited, biotite dehydration melting (a pelitic source) whereas the high Rb/Sr suites (e.g. Bloedkoppie leucogranite, Stinkbank leucogranite, Salem Swakopmund, Leucocratic Stink bank granite) reflect biotite-limited, biotite dehydration melting (a greywacke source). Alaskites from the Damara belt have major element compositions which are consistent with muscovite dehydration melting, and their positive Eu anomalies are linked to high K2O reflecting K-feldspar entrainment. Combined Zr and LREE (light rare earth element) solubility models indicate that insufficient time (probably less than 104 years) had elapsed between melt generation and melt extraction to ensure that the alaskite melts attained their equilibrium concentrations of Zr and the LREEs. In contrast, the leucogranites and Salem-type granites have attained their equilibrium inventories of these trace elements. Combined Fe2O3 and MgO contents in some samples from two granitoids (the Salem Goas and Donkerhuk Onanis intrusions) are higher than those readily attainable by biotite dehydration melting indicating either: (1) that they contain a contribution from melts generated by incipient garnet breakdown or; (2) that they contain small amounts of an entrained ferromagnesian phase.

Instant controlled pressure drop technology and ultrasound assisted extraction for sequential extraction of essential oil and antioxidants.

PubMed

Allaf, Tamara; Tomao, Valérie; Ruiz, Karine; Chemat, Farid

2013-01-01

The instant controlled pressure drop (DIC) technology enabled both the extraction of essential oil and the expansion of the matrix itself which improved solvent extraction. The sequential use of DIC and Ultrasound Assisted Extraction (UAE) triggered complementary actions materialized by supplementary effects. We visualized these combination impacts by comparing them to standard techniques: Hydrodistillation (HD) and Solvent Extraction (SE). First, the extraction of orange peel Essential Oils (EO) was achieved by HD during 4h and DIC process (after optimization) during 2 min; EO yields was 1.97 mg/g dry material (dm) with HD compared to 16.57 mg/g d m with DIC. Second, the solid residue was recovered to extract antioxidant compounds (naringin and hesperidin) by SE and UAE. Scanning electron microscope showed that after HD the recovered solid shriveled as opposite to DIC treatment which expanded the product structure. HPLC analyses showed that the best kinetics and yields of naringin and hesperidin extraction was when DIC and UAE are combined. Indeed, after 1h of extraction, DIC treated orange peels with UAE were 0.825 ± 1.6 × 10(-2)g/g of dry material (dm) for hesperidin and 6.45 × 10(-2) ± 2.3 × 10(-4)g/g d m for naringin compared to 0.64 ± 2.7 × 10(-2)g/g of dry material (dm) and 5.7 × 10(-2) ± 1.6 × 10(-3)g/g d m, respectively with SE. By combining DIC to UAE, it was possible to enhance kinetics and yields of antioxidant extraction. Copyright © 2012 Elsevier B.V. All rights reserved.

Characteristics of Frozen Yoghurt Enriched with Red Dragon Fruit Skin Extracts (Hylocereus polyrhizus)

NASA Astrophysics Data System (ADS)

Analianasari; Apriyani, M.

2018-01-01

The composition of the dragon fruit skin with fruit has a weight of 30-35% of the fruit weight and has not been widely utilized. Previous studies have suggested that red dragon fruit skin extracts with water solvent contain 1.1 mg / 100 ml anthocyanin. The content of anthocyanin can function lower cholesterol content in blood, besides red dragon fruit skin contains fiber about 46,7% which is very good for health. This study aims to determine the chemical characteristics of frozen yogurt red dragon skin fruit to antioxidant levels, fiber content, pH, Total acid content and frozen yogurt melting time. The design of the research was Randomized Complete Design (RAL) of 1 factor, which was treated as red dragon skin fruit extract, consisting of 4 treatment levels: 0%, 25%, 35%, and 45%. The results showed that the addition of red dragon fruit extract increased antioxidant levels ranging from 4.00 to 12.25%, crude fiber content ranged from 1.037 to 1.625%, total acid ranged from 0.73 to 1.14%, and decreased the pH value of 5, 48 - 4.39 and has a melting time of frozen yogurt 17.20 - 22.88 minutes.

Fitting It All In: Adapting a Green Chemistry Extraction Experiment for Inclusion in an Undergraduate Analytical Laboratory

ERIC Educational Resources Information Center

Buckley, Heather L.; Beck, Annelise R.; Mulvihill, Martin J.; Douskey, Michelle C.

2013-01-01

Several principles of green chemistry are introduced through this experiment designed for use in the undergraduate analytical chemistry laboratory. An established experiment of liquid CO2 extraction of D-limonene has been adapted to include a quantitative analysis by gas chromatography. This facilitates drop-in incorporation of an exciting…

Extraction of temperature dependent electrical resistivity and thermal conductivity from silicon microwires self-heated to melting temperature

NASA Astrophysics Data System (ADS)

Bakan, Gokhan; Adnane, Lhacene; Gokirmak, Ali; Silva, Helena

2012-09-01

Temperature-dependent electrical resistivity, ρ(T), and thermal conductivity, k(T), of nanocrystalline silicon microwires self-heated to melt are extracted by matching simulated current-voltage (I-V) characteristics to experimental I-V characteristics. Electrical resistivity is extracted from highly doped p-type wires on silicon dioxide in which the heat losses are predominantly to the substrate and the self-heating depends mainly on ρ(T) of the wires. The extracted ρ(T) decreases from 11.8 mΩ cm at room-temperature to 5.2 mΩ cm at 1690 K, in reasonable agreement with the values measured up to ˜650 K. Electrical resistivity and thermal conductivity are extracted from suspended highly doped n-type silicon wires in which the heat losses are predominantly through the wires. In this case, measured ρ(T) (decreasing from 20.5 mΩ cm at room temperature to 12 mΩ cm at 620 K) is used to extract ρ(T) at higher temperatures (decreasing to 1 mΩ cm at 1690 K) and k(T) (decreasing from 30 W m-1 K-1 at room temperature to 20 W m-1 K-1 at 1690 K). The method is tested by using the extracted parameters to model wires with different dimensions. The experimental and simulated I-V curves for these wires show good agreement up to high voltage and temperature levels. This technique allows extraction of the electrical resistivity and thermal conductivity up to very high temperatures from self-heated microstructures.

Energetics of metastudtite and implications for nuclear waste alteration

PubMed Central

Guo, Xiaofeng; Ushakov, Sergey V.; Labs, Sabrina; Curtius, Hildegard; Bosbach, Dirk; Navrotsky, Alexandra

2014-01-01

Metastudtite, (UO2)O2(H2O)2, is one of two known natural peroxide minerals, but little is established about its thermodynamic stability. In this work, its standard enthalpy of formation, −1,779.6 ± 1.9 kJ/mol, was obtained by high temperature oxide melt drop solution calorimetry. Decomposition of synthetic metastudtite was characterized by thermogravimetry and differential scanning calorimetry (DSC) with ex situ X-ray diffraction analysis. Four decomposition steps were observed in oxygen atmosphere: water loss around 220 °C associated with an endothermic heat effect accompanied by amorphization; another water loss from 400 °C to 530 °C; oxygen loss from amorphous UO3 to crystallize orthorhombic α-UO2.9; and reduction to crystalline U3O8. This detailed characterization allowed calculation of formation enthalpy from heat effects on decomposition measured by DSC and by transposed temperature drop calorimetry, and both these values agree with that from drop solution calorimetry. The data explain the irreversible transformation from studtite to metastudtite, the conditions under which metastudtite may form, and its significant role in the oxidation, corrosion, and dissolution of nuclear fuel in contact with water. PMID:25422465

Energetics of metastudtite and implications for nuclear waste alteration

DOE PAGES

Guo, Xiaofeng; Ushakov, Sergey V.; Labs, Sabrina; ...

2014-11-24

Metastudtite, (UO 2)O 2(H 2O) 2, is one of two known natural peroxide minerals, but little is established about its thermodynamic stability. In this work, its standard enthalpy of formation, $-$1,779.6 ± 1.9 kJ/mol, was obtained by high temperature oxide melt drop solution calorimetry. Decomposition of synthetic metastudtite was characterized by thermogravimetry and differential scanning calorimetry (DSC) with ex situ X-ray diffraction analysis. We observed four decomposition steps in oxygen atmosphere: water loss around 220 °C associated with an endothermic heat effect accompanied by amorphization; another water loss from 400 °C to 530 °C; oxygen loss from amorphous UO 3more » to crystallize orthorhombic α-UO 2.9; and reduction to crystalline U 3O 8. This detailed characterization allowed calculation of formation enthalpy from heat effects on decomposition measured by DSC and by transposed temperature drop calorimetry, and both these values agree with that from drop solution calorimetry. The data explain the irreversible transformation from studtite to metastudtite, the conditions under which metastudtite may form, and its significant role in the oxidation, corrosion, and dissolution of nuclear fuel in contact with water.« less

Determination of ochratoxin A in fruit juice by high-performance liquid chromatography after vortex-assisted emulsification microextraction based on solidification of floating organic drop.

PubMed

Asadi, Mohammad

2018-03-01

A rapid, simple, and green vortex-assisted emulsification microextraction method based on solidification of floating organic drop was developed for the extraction and determination of ochratoxin A (OTA) with high-performance liquid chromatography. Some factors influencing the extraction efficiency of OTA such as the type and volume of extraction solvent, sample pH, salt concentration, vortex time, and sample volume were optimized. Under optimized conditions, the calibration curve exhibited linearity in the range of 50.0-500 ng L -1 with a coefficient of determination higher than 0.999. The limit of detection was 15.0 ng L -1 . The inter- and intra-assays relative standard deviations were in a range of 4.7-8.7%. The accuracy of the developed method was investigated through recovery experiments, and it was successfully used for the quantification of OTA in 40 samples of fruit juice.

Jasmine flower extract lowers prolactin.

PubMed

Finny, Philip; Stephen, Charles; Jacob, Rajesh; Tharyan, Prathap; Seshadri, Mandalam S

2015-04-01

Antipsychotic drugs frequently cause amenorrhoea and galactorrhoea. Jasmine flowers used topically were as effective as oral Bromocriptine in suppressing puerperal lactation. This study aims to evaluate the efficacy and safety of intranasal jasmine flower extract (JFE) to reduce prolactin levels of patients on stable doses of antipsychotic drugs. This is a randomized, double blind, crossover clinical trial. An aqueous-ethanol extract of jasmine flowers was prepared and used as nasal drops. A decrease in serum prolactin of ≥25 ng/mL was considered a significant response. Ten out of 35 women had a significant drop in the serum prolactin while on the JFE. The non-responders to JFE were on higher doses of antipsychotic drugs. The main side effect was a transient and mild burning sensation in the nose. A cost analysis favoured JFE over dopamine agonists. JFE contains a prolactin-lowering substance which needs further characterisation. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Modelling melting in crustal environments, with links to natural systems in the Nepal Himalayas

NASA Astrophysics Data System (ADS)

Isherwood, C.; Holland, T.; Bickle, M.; Harris, N.

2003-04-01

Melt bodies of broadly granitic character occur frequently in mountain belts such as the Himalayan chain which exposes leucogranitic intrusions along its entire length (e.g. Le Fort, 1975). The genesis and disposition of these bodies have considerable implications for the development of tectonic evolution models for such mountain belts. However, melting processes and melt migration behaviour are influenced by many factors (Hess, 1995; Wolf &McMillan, 1995) which are as yet poorly understood. Recent improvements in internally consistent thermodynamic datasets have allowed the modelling of simple granitic melt systems (Holland &Powell, 2001) at pressures below 10 kbar, of which Himalayan leucogranites provide a good natural example. Model calculations such as these have been extended to include an asymmetrical melt-mixing model based on the Van Laar approach, which uses volumes (or pseudovolumes) for the different end-members in a mixture to control the asymmetry of non-ideal mixing. This asymmetrical formalism has been used in conjunction with several different entropy of mixing assumptions in an attempt to find the closest fit to available experimental data for melting in simple binary and ternary haplogranite systems. The extracted mixing data are extended to more complex systems and allow the construction of phase relations in NKASH necessary to model simple haplogranitic melts involving albite, K-feldspar, quartz, sillimanite and {H}2{O}. The models have been applied to real bulk composition data from Himalayan leucogranites.

LaRC TPI 1500 series polymers

NASA Technical Reports Server (NTRS)

Hou, Tan-Hung; Bai, Jia-Mo

1990-01-01

The crystallization behavior and the melt flow properties of two batches of 1500 series LaRC-TPI polymers from Mitsui Toatsu Chemicals (MTC) were investigated. The characterization methods include Differential Scanning Calorimetry, the x ray diffractography and the melt rheology. The as-received materials possess initial crystalline melting peak temperatures of 295 and 305 C, respectively. These materials are less readily recrystallizable at elevated temperatures when compared to other semicrystalline thermoplastics. For the samples annealed at temperatures below 330 C, a semicrystalline polymer can be obtained. On the other hand, a purely amorphous structure is realized in the samples annealed at temperatures above 330 C. Isothermal crystallization kinetics were studied by means of the simple Avrami equation. The viscoelastic properties at elevated temperatures below and above glass transition temperature of the polymers were measured. Information with regard to the molecule sizes and distributions in these polymers were also extracted from melt rheology.

Experimental Partitioning of Chalcophile Elements between Mantle Silicate Minerals and Basaltic Melt at High Pressures and Temperatures - Implications for Sulfur Geochemistry of Mantle and Crust

NASA Astrophysics Data System (ADS)

Dasgupta, R.; Jego, S.; Ding, S.; Li, Y.; Lee, C. T.

2015-12-01

The behavior of chalcophile elements during mantle melting, melt extraction, and basalt differentiation is critical for formation of ore deposits and geochemical model and evolution of crust-mantle system. While chalcophile elements are strongly partitioned into sulfides, their behavior with different extent of melting, in particular, in the absence of sulfides, can only be modeled with complete knowledge of the partitioning behavior of these elements between dominant mantle minerals and basaltic melt with or without dissolved sulfide (S2-). However, experimental data on mineral-melt partitioning are lacking for many chalcophile elements. Crystallization experiments were conducted at 3 GPa and 1450-1600 °C using a piston cylinder and synthetic silicate melt compositions similar to low-degree partial melt of peridotite. Starting silicate mixes doped with 100-300 ppm of each of various chalcophile elements were loaded into Pt/graphite double capsules. To test the effect of dissolved sulfur in silicate melt on mineral-melt partitioning of chalcophile elements, experiments were conducted on both sulfur-free and sulfur-bearing (1100-1400 ppm S in melt) systems. Experimental phases were analyzed by EPMA (for major elements and S) and LA-ICP-MS (for trace elements). All experiments produced an assemblage of cpx + melt ± garnet ± olivine ± spinel and yielded new partition coefficients (D) for Sn, Zn, Mo, Sb, Bi, Pb, and Se for cpx/melt, olivine/melt, and garnet/melt pairs. Derived Ds (mineral/basalt) reveal little effect of S2- in the melt on mineral-melt partition coefficients of the measured chalcophile elements, with Ds for Zn, Mo, Bi, Pb decreasing by less than a factor of 2 from S-free to S-bearing melt systems or remaining similar, within error, between S-free and S-bearing melt systems. By combining our data with existing partitioning data between sulfide phases and silicate melt we model the fractionation of these elements during mantle melting and basalt crystallization. The model results are compared with the chalcophile element abundance in oceanic basalts. We will discuss the implications of our new partitioning data and model results on sulfur and chalcophile element geochemistry of mantle source regions of ocean floor basalts and the fate of sulfides during mantle melting.

Electrolytic production of oxygen from lunar resources

NASA Technical Reports Server (NTRS)

Keller, Rudolf

1991-01-01

Some of the most promising approaches to extract oxygen from lunar resources involve electrochemical oxygen generation. In a concept called magma electrolysis, suitable oxides (silicates) which are molten at 1300 to 1500 C are then electrolyzed. Residual melt can be discarded after partial electrolysis. Alternatively, lunar soil may be dissolved in a molten salt and electrolyzed. In this approach, temperatures are lower and melt conductances higher, but electrolyte constituents need to be preserved. In a different approach ilmenite is reduced by hydrogen and the resulting water is electrolyzed.

Degassing of H2O in a phonolitic melt: A closer look at decompression experiments

NASA Astrophysics Data System (ADS)

Marxer, Holger; Bellucci, Philipp; Nowak, Marcus

2015-05-01

Melt degassing during magma ascent is controlled by the decompression rate and can be simulated in decompression experiments. H2O-bearing phonolitic melts were decompressed at a super-liquidus T of 1323 K in an internally heated argon pressure vessel, applying continuous decompression (CD) as well as to date commonly used step-wise decompression (SD) techniques to investigate the effect of decompression method on melt degassing. The hydrous melts were decompressed from 200 MPa at nominal decompression rates of 0.0028-1.7 MPa·s- 1. At final pressure (Pfinal), the samples were quenched rapidly at isobaric conditions with ~ 150 K·s- 1. The bubbles in the quenched samples are often deformed and dented. Flow textures in the glass indicate melt transport at high viscosity. We suggest that this observation is due to bubble shrinkage during quench. This general problem was mostly overlooked in the interpretation of experimentally degassed samples to date. Bubble shrinkage due to decreasing molar volume (Vm) of the exsolved H2O in the bubbles occurs during isobaric rapid quench until the melt is too viscous too relax. The decrease of Vm(H2O) during cooling at Pfinal of the experiments results in a decrease of the bubble volume by a shrinking factor Bs: At nominal decompression rates > 0.17 MPa·s- 1 and a Pfinal of 75 MPa, the decompression method has only minor influence on melt degassing. SD and CD result in high bubble number densities of 104-105 mm- 3. Fast P drop leads to immediate supersaturation with H2O in the melt. At such high nominal decompression rates, the diffusional transport of H2O is limited and therefore bubble nucleation is the predominant degassing process. The residual H2O contents in the melts decompressed to 75 MPa increase with nominal decompression rate. After homogeneous nucleation is triggered, CD rates ≤ 0.024 MPa·s- 1 facilitate continuous reduction of the supersaturation by H2O diffusion into previously nucleated bubbles. Bubble number densities of CD samples with low nominal decompression rates are several orders of magnitude lower than for SD experiments and the bubble diameters are larger. The reproducibility of MSD experiments with low nominal decompression rates is worse than for CD runs. Commonly used SD techniques are therefore not suitable to simulate melt degassing during continuous magma ascent with low ascent rates.

Probing the melt zone of Kilauea Iki lava lake, Kilauea volcano, Hawaii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hardee, H.C.; Dunn, J.C.; Hills, R.G.

1981-12-01

New drilling techniques were recently used to drill and core the melt zone of Kilauea Iki lava lake to a depth of 93 m. A partial melt zone was found to exist at depths between 58 m and 89 m consisting of 40 volume percent melt. Downhole seismic shots detonated in and below the melt zone resulted in the first in situ measurements of seismic velocity directly through well characterized partial melt zone. Periodic seismic sources were used to effectively penetrate the highly fractured hydrothermal zone of the lava lake crust. Low velocity P-wave layers (< or =2.0 km/s) weremore » found at the surface, at 40 m depth, and at 90 m depth. Thermal convective experiments in the melt zone resulted in the first controlled in situ measurements of the interaction of water with a basaltic melt zone. Transient energy rates of 900 kW (980 kW/m/sup 2/) and steady rates of 85 kW (93 kW/m/sup 2/) were observed. The full water recovery (100%), high downhole steam temperatures (670 C), and high energy transfer rates (93 to 980 kW/m/sup 2/) observed in these thermal experiments are consistent with a closed cavity model where the injected water/steam directly contacted basaltic melt or near melt. In addition to understanding lava lakes, these seismic and thermal experiments have applications for the location of magma bodies in the crust and for the efficient extraction of energy from these bodies.« less

Evolution of Volcano-Plutonic Centers in the Northern Colorado River Extensional Corridor, Nevada-Arizona: Protracted Cycles of Replenishment, Mush Accumulation, Fractionation, and Melt Extraction

NASA Astrophysics Data System (ADS)

Miller, C. F.; Miller, J. S.; Claiborne, L. L.; Walker, B. A.; Faulds, J. E.; Wooden, J. L.

2007-12-01

Three major magmatic systems were simultaneously active during early development of the northern Colorado River extensional corridor. These systems, centered on Spirit Mountain batholith, Searchlight pluton, and Aztec Wash and Nelson plutons, include hypabyssal intrusions as well as coarser, deeper-seated rocks emplaced at depths of 5-13 km. Erupted products of Searchlight are clearly exposed; connections between the other systems and extensive coeval volcanic sequences, while very likely, remain unverified. Intrusion at each center began at 17-18 Ma and terminated with a dike swarm at ca. 15.5 Ma. Dikes, sills, and evidence for mingling document the frequent replenishment suggested by longevity of the centers. Quenched magmas in pillows, dikes, and chilled margins indicate that input included trachybasalt (49- 52 wt pct SiO2), trachydacite (quartz monzonite; 62-65 wt pct SiO2), and low-Si rhyolite (granite; ca. 73 wt pct SiO2); similar magmas formed a large part of the regional volcanic sequence. Some of the basalt may represent juvenile magma from enriched mantle, but Sr and Nd isotopic data indicate that all other input magmas are hybrids with both juvenile and ancient crustal components. Although local mixing is evident from field and geochemical evidence, the system-wide hybridization occurred at deeper crustal levels prior to emplacement into the upper crust. Whole-rock elemental compositions, field relations, crystal-size distributions and textures within the volcanic rocks and co-genetic intrusions indicate repeated cycles of magma emplacement and extraction of fractionated melt from cumulate mush. Cumulates are enriched in Sr and Ba and have positive Eu anomalies relative to input magmas. The melt-rich extracts have high-silica rhyolite compositions. They are exposed in plutons as small dikes and large subhorizontal sheets and roof zones comprising fine-grained, commonly vesicle-rich aplitic granite, and they erupted from the Searchlight center and probably from the others. These rocks are extremely depleted in Sr, Ba, and Eu, and middle REE, low in light REE, P, Ti, and Zr, and enriched in Rb, reflecting fractionation of feldspars and accessory minerals. Their high SiO2 (77-79 wt pct) attests to fractionation at shallow levels, consistent with emplacement depths of the upper parts of the plutons. SHRIMP U-Pb ages and compositional zoning in zircon also indicate repeated cycles of growth from fractionating melts and recycling into less evolved melts. Most samples have two or more distinguishable age populations, and many individual grains show evidence for resorption. Compositions of zones indicate that grains experienced dramatic temperature fluctuations and were transferred from highly fractionated to unfractionated melts. Taken together, these data indicate that the intrusions formed and were modified by repeated (a) felsic replenishment that eventually formed thick crystal mush; (b) mafic replenishments that helped to maintain a thermal balance; (c) extraction of fractionated melt into local conduits or ponding zones, to the roof, or to erupt at the surface; (d) rejuvenation of the mush by the preceding processes, entraining and transporting crystals and blurring previous intrusive contacts.

Prevention effect in selenite-induced cataract in vivo and antioxidative effects in vitro of Crataegus pinnatifida leaves.

PubMed

Wang, Tao; Zhang, Peng; Zhao, Chunfeng; Zhang, Yi; Liu, Hong; Hu, Limin; Gao, Xiumei; Zhang, Deqin

2011-07-01

Cataract is the leading cause of blindness worldwide. It is a multifactorial disease primarily associated with oxidative stress produced by free radicals. The present study was undertaken to evaluate the anticataract potential of Crataegus pinnatifida (hawthorn tree) leaves extract in selenite-induced cataract in vivo and antioxidant effects in vitro. In vitro antioxidant assay of C. pinnatifida leaves extract on NO production inhibition, aldose reductase inhibition, and O(2)(-) radical scavenging activities gave the IC(50) of 98.3, 89.7, and 5.98 μg/mL, respectively. To characterize some major compounds in C. pinnatifida leaves extract, nine flavonoids were identified via LC-MS/MS qualitative analysis. Based on in vitro screening results, C. pinnatifida leaves extract eye drops in 0.1% hydroxypropyl methyl cellulose solution were prepared to evaluate the anticataract potential in vivo. Administration of C. pinnatifida leaves extract eye drops alternately three times a day in rat pups with selenite-induced oxidative stress significantly increased serum SOD and CAT activities, and tended to reduce MDA level compared with control group. The antioxidant enzyme SOD, CAT, and GSH activities in lens showed a significant increase. These results may be applied in the future for the prevention and treatment of cataracts.

Kinetic D/H fractionation during hydration and dehydration of silicate glasses, melts and nominally anhydrous minerals

NASA Astrophysics Data System (ADS)

Roskosz, M.; Deloule, E.; Ingrin, J.; Depecker, C.; Laporte, D.; Merkel, S.; Remusat, L.; Leroux, H.

2018-07-01

The distribution of hydrogen isotopes during diffusion-driven aqueous processes in silicate glasses, melts and crystals was investigated. Hydration/dehydration experiments were performed on silica glasses at 1000 °C and 1 bar total pressure. Dehydration triggered by decompression-driven bubble nucleation and growth was performed on rhyolitic melts at 800 °C and a few hundred MPa. Hydrogen extraction from a nominally anhydrous mineral (grossular) single crystal was carried out at 800 °C and ambient pressure. After these three series of experiments, pronounced water (sensu lato) concentration profiles were observed in all recovered samples. In the grossular single-crystal, a large spatial variation in H isotopes (δD variation > 550‰) was measured across the sample. This isotopic distribution correlates with the hydrogen extraction profile. The fit to the data suggests an extreme decoupling between hydrogen and deuterium diffusion coefficients (DH and DD respectively), akin to the decoupling expected in a dilute ideal gas (DH/DD ≈ 1.41). Conversely, no measurable spatially- and time-resolved isotopic variations were measured in silicate glasses and melts. This contrasted behavior of hydrogen isotopes likely stands in the different water speciation and solution mechanisms in the three different materials. Glasses and melts contain essentially hydroxyl and molecular water groups but the mobile species is molecular water in both cases. Protonated defects make up most of the water accommodated in grossular and other nominally anhydrous minerals (NAM). These defects are also the mobile species that diffuse against polarons. These results are crucial to accurately model the degassing behavior of terrestrial and lunar magmas and to derive the initial D/H of water trapped in fluid inclusions commonly analyzed in mantle NAMs, which suffered complex geological histories.

Magma Electrolysis: An update

NASA Technical Reports Server (NTRS)

Colson, Russell O.; Haskin, Larry A.

1991-01-01

Electrolytic extraction of O2 from molten lunar soil is conceptually simple and thus a candidate process for producing O2 on the Moon. Possible container and electrode materials are being tested for durability in corrosive high-temperature silicate melts and looking for complications that might increase energy requirements. Gaseous oxygen is being produced by electrolysis of 1-2 gram quantities of silicate melts in spinel (MgAl2O4) crucibles; in these melts, spinel is a stable phase. The concentration of FeO was kept low because FeO decrease O2 production efficiency. Platinum electrodes were placed about 0.5 cm apart in the melt. The spinel crucible was still intact after 40 minutes of electrolysis, when the experiment was halted for examination. The Pt anode was also intact; its Pt was maintained in a dynamci state in which the anode was continuously oxidized but quickly reduced again by the silicate melt, inhibiting migration of Pt away from the anode. In melts with low concentrations of Al2O3 + SiO2 (2 wt percent), the energy of resistance heating was only approximately equal to 10 to 20 percent of the theoretical amount required to produce O2. In melts substantially more concentrated in Al2O3 + SiO2, higher melt viscosity resulted in frothing that, in the worst case, caused high enough melt resistivities to raise the energy requirements to nearly 10 times theoretical. Both Fe and Si are produced at the cathode; in iron-rich melts, a- and c-iron and molten ferrosilicon were observed. Production was also observed at the cathode of a previously unrecognized gas; which is not yet identified. The solubility of metallic species was measured in silicate melts. They are too low to reduce significantly the efficiency of O2 production.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathur, Anoop

A key technological issue facing the success of future Concentrating Solar Thermal Power (CSP) plants is creating an economical Thermal Energy Storage (TES) system. Current TES systems use either sensible heat in fluids such as oil, or molten salts, or use thermal stratification in a dual-media consisting of a solid and a heat-transfer fluid. However, utilizing the heat of fusion in inorganic molten salt mixtures in addition to sensible heat , as in a Phase change material (PCM)-based TES, can significantly increase the energy density of storage requiring less salt and smaller containers. A major issue that is preventing themore » commercial use of PCM-based TES is that it is difficult to discharge the latent heat stored in the PCM melt. This is because when heat is extracted, the melt solidifies onto the heat exchanger surface decreasing the heat transfer. Even a few millimeters of thickness of solid material on heat transfer surface results in a large drop in heat transfer due to the low thermal conductivity of solid PCM. Thus, to maintain the desired heat rate, the heat exchange area must be large which increases cost. This project demonstrated that the heat transfer coefficient can be increase ten-fold by using forced convection by pumping a hyper-eutectic salt mixture over specially coated heat exchanger tubes. However,only 15% of the latent heat is used against a goal of 40% resulting in a projected cost savings of only 17% against a goal of 30%. Based on the failure mode effect analysis and experience with pumping salt at near freezing point significant care must be used during operation which can increase the operating costs. Therefore, we conclude the savings are marginal to justify using this concept for PCM-TES over a two-tank TES. The report documents the specialty coatings, the composition and morphology of hypereutectic salt mixtures and the results from the experiment conducted with the active heat exchanger along with the lessons learnt during experimentation.« less

The influence of magma degassing on entrapment pressures recorded in olivine-hosted melt inclusions

NASA Astrophysics Data System (ADS)

Gaetani, G. A.

2013-12-01

The concentrations of H2O and CO2 in olivine-hosted melt inclusions provide estimates for the pressures at which they were entrapped, and represent an important source of information on the depths at which basaltic magmas crystallize [1]. Results from recent dehydration experiments demonstrate that diffusive loss of H2O from melt inclusions, driven by degassing of the external magma, leads to significant decreases to pressure within the inclusion [2, 3]. This, in turn, lowers the solubility of CO2 in the included melt causing a vapor to exsolve and form a bubble. This process has the potential to significantly modify estimates of entrapment pressures derived from volatile concentrations in olivine hosted melt inclusions. I have developed a quantitative model that describes this process, allowing the influence of degassing on entrapment pressures to be rigorously evaluated. Diffusive loss of H2O from the inclusions was determined using the model of [3]. An equation of state (EOS) for the silicate melt was taken from the results of [4] and [5], while the EOS for H2O-CO2 vapor was taken from [6]. The solubilities of H2O and CO2 in the silicate melt were derived from VolatileCalc [7]. Modeling results demonstrate that degassing of H2O-rich magma produces significant pressure drops, so that entrapment pressures never exceed crustal values and always represent a minimum. Conversely, degassing of H2O-poor magma does not significantly perturb the H2O content of olivine-hosted melt inclusions. Therefore, these inclusions preserve reliable records of the pressures at which they were entrapped. These results are consistent with a global compilation of olivine-hosted melt inclusion entrapment pressures presented by [3]. References: [1] Wanless, VD, and Shaw, AM, Nature Geosci, 5, 651-655 (2012); [2] Gaetani, GA, et al., Geology, 40, 915-918 (2012); [3] Bucholz, CE, et al., Earth Planet Sci Lett, 374, 145-155 (2013); [4] Lange, R. A., and Carmichael, ISE, Geochim Cosmochim Acta, 51, 2931-2946, (1987); [5] Kress, VC, and Carmichael, ISE, Contrib Mineral Petrol, 108, 82-92 (1991); [6] Duan, Z, and Zhang, Z, Geochim Cosmochim Acta, 70, 2311-2324 (2006); [7] Newman, S, and Lowenstern, JB, Comput Geosci, 28, 597-604 (2002).

Kinetic Controls on Formation of Textures in Rapidly Cooled Rocks

NASA Technical Reports Server (NTRS)

Lofgren, Gary E.

2006-01-01

The crystallization of silicate melts is a complex process involving melts usually produced by partial melting and cooling environments that are rapid in volcanic lavas or so slow as to be auto-metamorphic in plutonic regimes. The volcanic lavas are amenable to laboratory study as are chondrules that comprise the bulk of chondritic meteorites. Dynamic crystallization studies of basalt and chondrule melts have shown that nucleation has a more profound effect on the final texture than the cooling or crystal growth rates. The sequence of crystal shapes grown at increasing degrees of supercooling (DELTA T) or cooling rate demonstrates the effect of increasing growth rate. Equant or euhedral crystals become skeletal, then dendritic and ultimately spherulitic indicating the nucleation temperature and the DELTA T when growth began. Because crystals cannot grow until they nucleate, cooling rate does not always correlate with crystal growth rate and thus crystal shape. Silicate melts cooled at the same rate can have drastically different textures depending on the temperature of nucleation. A dynamic crystallization study of basaltic rocks shows that basaltic lavas must erupt with sufficient crystals present in the melt to act as nuclei and foster growth. With nuclei present, growth will begin when the temperature drops below the liquidus temperature and typical basaltic textures such as intersertal, intergranular or subophitic will form. If nuclei are not present, crystallization will not begin immediately and the DELTA T will increase until embryos in the melts become nuclei. The DELTA T present when grow begins dictates the growth rate and the crystal shapes and thus the rock texture. If nucleation is delayed, growth will take place at high DELTA T and the crystals will favor skeletal or dendritic shapes. Chondrules are usually considered crystallized melt droplets and clearly some are, but most are not. Most chondrules have porphyritic textures that cannot develop from totally melted droplets because nucleation is delayed during cooling and growth occurs at high DELTA T and the resulting textures are dendritic or spherulitic. The porphyritic textures will develop only if the chondrule is partially molten and begins to crystallize immediately upon cooling. Chondrule compositions are close to komatiites and these studies bear on the origin of their textures as well.

Ties of Heat and Mass Transport Properties in Glasses and Melts, with Emphasis on Natural Lava Compositions

NASA Astrophysics Data System (ADS)

Hofmeister, A. M.; Whittington, A. G.; Robert, G.; Sehlke, A.

2016-12-01

We have discovered strong ties of mass and heat transport properties in glasses and melts via coordinated measurements of thermal diffusivity (D) and viscosity (η). Over the course of several studies we have compared over 50 remelted natural lavas, tektites, and synthetic glasses and melts, with substantially different chemical compositions, e.g., from 50 to 100% silica, and with slight variations in H and Fe cations and the presence/absence of Al. We use laser flash analysis to obtain D, which avoids contact and radiative errors and constrain η over a wide range of temperature (T). We use a combination of parallel-plate and concentric-cylinder viscometry to obtain η from the glass transition to above the liquidus. Our most recent studies include differential scanning calorimetric measurements of heat capacity (CP) to calculate their thermal conductivity (k), and we are now measuring thermal expansivity using dilatometry. The combined datasets show consistent macroscopic behavior, providing an improved understanding of microscopic behavior, particularly of heat transport properties, which have been misunderstood. Both viscosity and the glass transition temperature decrease with decreasing melt polymerization. Clear correlations exist between D of glass or melt with Si content, density, NBO/T, and, most strongly, with fragility (obtained from η). Glass thermal diffusivity is represented by D = FT-G +HT, where F, G and H are fitting parameters. For melts, D drops upon melting but we could only resolve D/T for a small number of samples. The results show that high-T behavior is controlled by Fe oxidation state and polymerization and involves radiative transfer (HT) but at infrared frequencies. In disordered materials, acoustic scattering is less important to heat transfer than is IR absorption/re-emissions. We find that k for glasses is described by a Maier-Kelly formula, consistent with the T response being dominated by CP. Trends in k are irregular due to k being the convolution of three physical properties. Nonetheless, basaltic melts are constrained to k 1.4±0.1 Wm-1k-1. Low values for thermal diffusivity and viscosity for basaltic melts suggests that basalts transfer heat much more efficiently by advection than by conduction alone, which pertains to upper mantle processes.

Peridotite xenoliths from the Chersky belt (Yakutia): Infiltrated carbonate-rich melts leaving no metasomatic record

NASA Astrophysics Data System (ADS)

Tschegg, C.; Ntaflos, Th.

2012-04-01

The Chersky seismic belt (NE-Russia) forms the modern plate boundary of the Eurasian-North American continental plate. The geodynamic evolution of this continent-continent setting is highly complex and it remains a matter of debate, how the extent of the Mid-Arctic Ocean spreading influenced the North Asian continent in this region since the Eocene. We constrained a model (Tschegg et al. 2011, Lithos) showing that volcanism in the Chersky area was triggered by extension and thinning of the lithosphere combined with adiabatic upwelling of the underlying mantle at 37 Ma. This implicates that the rift tectonics of the Mid-Arctic Ocean, at that time, affected the North Asian continent causing volcanic activity. Luckily, the basanites that were studied for these purposes host a representative number of peridotite xenoliths, which allow further constraints on the evolution of this area. The suite of spinel peridotites (lherzolites and harzburgites), pyroxenites and mega-crysts enable to characterize upper mantle conditions as well as to observe different processes within the lithospheric mantle beneath the Chersky belt. Equilibration temperatures of the spinel lherzolites reveal approx. 900-1000 °C at pressures of 1-2 GPa, with melt extraction volumes around 4 %. The analyzed spinel harzburgites reflect equilibration at lower P-T conditions and around 8 % higher melt extraction rates. We were able to find a completely preserved interstitial melt droplet in a lherzolite, in which a primary dolomite is in perfect phase contact with Na-rich alumosilicate glass and sodalite. Based on detailed and integrated investigations, we reconstructed origin and evolution of this spectacular carbonatic liquid that at depth differentiated from a carbonated silicate melt to an immiscible carbonate and silicate liquid, entered the lherzolite and quenched shortly before it was transported in the xenolith to the earth surface. To our surprise, the carbonate-rich melt infiltration did not cause any kind of metasomatism of the peridotite mineral assemblage, neither modally nor cryptically. Clinopyroxene trace element compositions clearly indicate that some of the studied rocks were influenced by percolating hydrous and basaltic melts, metasomatism through carbonate-rich melt or CO2-rich fluids, however, can certainly be ruled out for the whole suite of peridotites.

Effect of Inverter Power Source Characteristics on Welding Stability and Heat Affected Zone Dimensions

NASA Astrophysics Data System (ADS)

Il'yaschenko, D. P.; Chinakhov, D. A.; Mamadaliev, R. A.

2018-01-01

The paper presents results the research in the effect of power sources dynamic characteristics on stability of melting and electrode metal transfer to the weld pool shielded metal arc welding. It is proved that when applying inverter-type welding power sources, heat and mass transfer characteristics change, arc gap short-circuit time and drop generation time are reduced. This leads to reduction of weld pool heat content and contraction of the heat-affected zone by 36% in comparison the same parameters obtained using a diode rectifier.

Research of metal solidification in zero-g state. [test apparatus and instrumentation

NASA Technical Reports Server (NTRS)

Aubin, W. M.; Larson, D., Jr.; Geschwind, G. I.

1973-01-01

An experiment test apparatus that allows metal melting and resolidification in the three seconds available during free fall in a drop tower was built and tested in the tower. Droplets (approximately 0.05 cm) of pure nickel and 1090 steel were prepared in this fashion. The apparatus, including instrumentation, is described. As part of the instrumentation, a method for measuring temperature-time histories of the free floating metal droplets was developed. Finally, a metallurgical analysis of the specimens prepared in the apparatus is presented.

A hybrid electromagnetic-acoustic levitator for the containerless processing of undercooled melts

NASA Technical Reports Server (NTRS)

Hmelo, Anthony B.; Banerjee, Sharbari; Wang, Taylor G.

1992-01-01

The hybrid, acoustic-EM levitator discussed provides a small lifting force independently of its EM component by exciting an acoustic resonance that serves as a pressure node at the position of the EM-levitated specimen. The system also stabilizes and damps chaotic oscillations during specimen positioning, and can excite forced oscillations of levitated molten metals for drop-physics and thermophysical property measurements. Attention is given to the character and function of the atmosphere in the levitator. Noncontact temperature measurement is via single-color optical pyrometer.

Crustal formation and recycling in an oceanic environment in the early Earth

NASA Astrophysics Data System (ADS)

van Thienen, P.; van den Berg, A. P.; Vlaar, N. J.

2003-04-01

Several lines of evidence indicate higher mantle temperatures (by some hundreds of degrees) during the early history of the Earth. Due to the strong effect of temperature on viscosity as well as on the degree of melting, this enforces a geodynamic regime which is different from the present plate tectonics, and in which smaller scale processes play a more important role. Upwelling of a hotter mantle produces a thicker oceanic crust, of which the lower part may reside in the eclogite stability field. This facilitates delamination, making room for fresh mantle material which may partly melt and add new material to the crust (Vlaar et al., 1994). We present results of numerical thermo-chemical convection models including a simple approximate melt segregation mechanism in which we investigate this alternative geodynamic regime, and its effect on the cooling history and chemical evolution of the mantle. Our results show that the mechanism is capable of working on two scales. On a small scale, involving the lower boundary of the crust, delaminations and downward transport of eclogite into the upper mantle takes place. On a larger scale, involving the entire crustal column, (parts of) the crust may episodically sink into the mantle and be replaced by a fresh crust. Both are capable of significantly and rapidly cooling a hot upper mantle by driving partial melting and thus the generation of new crust. After some hundreds of millions of years, as the temperature drops, the mechanism shuts itself off, and the cooling rate significantly decreases. Vlaar, N.J., P.E. van Keken and A.P. van den Berg (1994), Cooling of the Earth in the Archaean: consequences of pressure-release melting in a hotter mantle, Earth and Planetary Science Letters, vol 121, pp. 1-18

Causes and extent of subduction-related highly siderophile element processing in oceanic mantle

NASA Astrophysics Data System (ADS)

O Driscoll, B.; Walker, R. J.; Day, J. M.; Daly, J. S.; Ash, R. D.

2013-12-01

Oceanic mantle samples that are accessible for study (e.g., abyssal and ophiolite peridotites) are commonly viewed as having undergone melt extraction at mid-ocean ridges (MOR). However, many ophiolite peridotites have been subjected to comparatively higher degrees of partial melting in supra-subduction zone (SSZ) environments too[1]. The ~497 Ma Leka Ophiolite, Norway, offers an ideal location for assessing the extent to which SSZ melting processes overprint the residual signatures of prior melt extraction. It comprises ~15 km[2] of well-exposed mantle and lower crustal peridotites that exhibit relatively limited serpentinisation. Extensive lithological heterogeneity is evident within the harzburgitic host rock, in the form of lenses and sheets of dunite, pyroxenite and chromitite. These have been interpreted as representing successive generations of SSZ-related channelised upper mantle melt migration and melt-rock interaction[2]. The integrated application of highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, Re) abundances and 187Os/188Os measurements of oceanic mantle peridotite has proved valuable in assessing the timing of mantle melting processes occurring within the upper mantle, as well as the scales of upper mantle heterogeneity[3,4]. At 497 Ma, the Os isotopic compositions of Leka harzburgites averaged ~2% more radiogenic than the projected average for abyssal peridotites[4] at that time. Several of the harzburgites are characterised by low initial 187Os/188Os (as low as 0.1202), interpreted as reflecting Proterozoic melt depletion, a common characteristic of melt-depleted peridotites comprising most ophiolites. Dunites, pyroxenites and chromitites show considerably more variable initial 187Os/188Os and HSE abundances; some pyroxenites have extreme Pt abundances (to 1-2 ppm), supra-chondritic Pt/Os and 187Os/188Os, yet some of the dunites are also characterised by 187Os/188Os well within the range of the harzburgites. A number of dunites have relatively radiogenic initial 187Os/188Os (up to 0.1385), suggesting that they either formed from selectively more radiogenic melt or that their development predates that of the ophiolite by ~500 Ma. Assuming that the significant lithological heterogeneity observed in the Leka upper mantle section was generated during SSZ melting, it appears that consequent modification of the HSE compositions and 187Os/188Os was restricted to pyroxenites and some, but perhaps not all, of the dunites. Mineral scale observations, coupled with a comparison of the Leka data and those from the ~492 Ma Shetland Ophiolite (Scotland)[3], suggest that sulphide/arsenide mobilisation during channelised melt-rock interactions is the trigger for fractionation of the HSE and modification of 187Os/188Os in ophiolite dunites. [1] Dilek and Furnes (2011) GSA Bulletin 123(3/4), 387-411 [2] Maaløe (2005) Mineralogy and Petrology 85, 163-204 [3] O'Driscoll et al. (2012) EPSL 333-334, 226-237 [4] Liu et al. (2009) EPSL 283, 122-132

Optimization of dispersive liquid-phase microextraction based on solidified floating organic drop combined with high-performance liquid chromatography for the analysis of glucocorticoid residues in food.

PubMed

Huang, Yuan; Zheng, Zhiqun; Huang, Liying; Yao, Hong; Wu, Xiao Shan; Li, Shaoguang; Lin, Dandan

2017-05-10

A rapid, simple, cost-effective dispersive liquid-phase microextraction based on solidified floating organic drop (SFOD-LPME) was developed in this study. Along with high-performance liquid chromatography, we used the developed approach to determine and enrich trace amounts of four glucocorticoids, namely, prednisone, betamethasone, dexamethasone, and cortisone acetate, in animal-derived food. We also investigated and optimized several important parameters that influenced the extraction efficiency of SFOD-LPME. These parameters include the extractant species, volumes of extraction and dispersant solvents, sodium chloride addition, sample pH, extraction time and temperature, and stirring rate. Under optimum experimental conditions, the calibration graph exhibited linearity over the range of 1.2-200.0ng/ml for the four analytes, with a reasonable linearity(r 2 : 0.9990-0.9999). The enrichment factor was 142-276, and the detection limits was 0.39-0.46ng/ml (0.078-0.23μg/kg). This method was successfully applied to analyze actual food samples, and good spiked recoveries of over 81.5%-114.3% were obtained. Copyright © 2017. Published by Elsevier B.V.

Prediction of as-cast grain size of inoculated aluminum alloys melt solidified under non-isothermal conditions

NASA Astrophysics Data System (ADS)

Du, Qiang; Li, Yanjun

2015-06-01

In this paper, a multi-scale as-cast grain size prediction model is proposed to predict as-cast grain size of inoculated aluminum alloys melt solidified under non-isothermal condition, i.e., the existence of temperature gradient. Given melt composition, inoculation and heat extraction boundary conditions, the model is able to predict maximum nucleation undercooling, cooling curve, primary phase solidification path and final as-cast grain size of binary alloys. The proposed model has been applied to two Al-Mg alloys, and comparison with laboratory and industrial solidification experimental results have been carried out. The preliminary conclusion is that the proposed model is a promising suitable microscopic model used within the multi-scale casting simulation modelling framework.

Stabilization of molten salt materials using metal chlorides for solar thermal storage.

PubMed

Dunlop, T O; Jarvis, D J; Voice, W E; Sullivan, J H

2018-05-29

The effect of a variety of metal-chlorides additions on the melting behavior and thermal stability of commercially available salts was investigated. Ternary salts comprised of KNO 3, NaNO 2, and NaNO 3 were produced with additions of a variety of chlorides (KCl, LiCl, CaCl 2 , ZnCl 2 , NaCl and MgCl 2 ). Thermogravimetric analysis and weight loss experiments showed that the quaternary salt containing a 5 wt% addition of LiCl and KCl led to an increase in short term thermal stability compared to the ternary control salts. These additions allowed the salts to remain stable up to a temperature of 630 °C. Long term weight loss experiments showed an upper stability increase of 50 °C. A 5 wt% LiCl addition resulted in a weight loss of only 25% after 30 hours in comparison to a 61% loss for control ternary salts. Calorimetry showed that LiCl additions allow partial melting at 80 °C, in comparison to the 142 °C of ternary salts. This drop in melting point, combined with increased stability, provided a molten working range increase of almost 100 °C in total, in comparison to the control ternary salts. XRD analysis showed the oxidation effect of decomposing salts and the additional phase created with LiCl additions to allow melting point changes to occur.

Heat Transfer and Observation of Droplet-Surface Interactions During Air-Mist Cooling at CSP Secondary System Temperatures

NASA Astrophysics Data System (ADS)

Huerta L., Mario E.; Mejía G., M. Esther; Castillejos E., A. Humberto

2016-04-01

Air-mists are key elements in the secondary cooling of modern thin steel slab continuous casters. The selection of water, W, and air, A, flow rates, and pressures in pneumatic nozzles open up a wide spectrum of cooling possibilities by their influence on droplet diameter, d, droplet velocity, v, and water impact flux, w. Nonetheless, due to the harsh environment resulting from the high temperatures and dense mists involved, there is very little information about the correlation between heat flux extracted, - q, and mist characteristics, and none about the dynamics of drop-wall interactions. For obtaining both kinds of information, this work combines a steady-state heat flux measuring method with a visualization technique based on a high-speed camera and a laser illumination system. For wall temperatures, T w, between ~723 K and ~1453 K (~450 °C and ~1180 °C), which correspond to film boiling regime, it was confirmed that - q increases with increase in v, w, and T w and with decrease in d. It should be noticed, however, that the increase in w generally decreases the spray cooling effectiveness because striking drops do not evaporate efficiently due to the interference by liquid remains from previous drops. Visualization of the events happening close to the surface also reveals that the contact time of the liquid with the surface is very brief and that rebounding, splashing, sliding, and levitation of drops lead to ineffective contact with the surface. At the center of the mist footprint, where drops impinge nearly normal to the surface those with enough momentum establish intimate contact with it before forming a vapor layer that pushes away the remaining liquid. Also, some drops are observed sliding upon the surface or levitating close to it; these are drops with low momentum which are influenced by the deflecting air stream. At footprint positions where oblique impingement occurs, frequently drops are spotted sliding or levitating and liquid films flowing in from inner positions are seen generating vapor cushions after having stayed in contact with the surface. Visualization of events taking place under high, ~500 kPa, and low, ~200 kPa, air nozzle pressure, p a, conditions suggests that the considerably larger heat extraction obtained under high p a is related to more frequent impingement of finer and faster drops that result in the formation of a dense fog of tiny secondary drops that moves tangentially close to the surface.

Reactive transport in a partially molten system with binary solid solution

NASA Astrophysics Data System (ADS)

Jordan, J.; Hesse, M. A.

2017-12-01

Melt extraction from the Earth's mantle through high-porosity channels is required to explain the composition of the oceanic crust. Feedbacks from reactive melt transport are thought to localize melt into a network of high-porosity channels. Recent studies invoke lithological heterogeneities in the Earth's mantle to seed the localization of partial melts. Therefore, it is necessary to understand the reaction fronts that form as melt flows across the lithological interface of a heterogeneity and the background mantle. Simplified melting models of such systems aide in the interpretation and formulation of larger scale mantle models. Motivated by the aforementioned facts, we present a chromatographic analysis of reactive melt transport across lithological boundaries, using theory for hyperbolic conservation laws. This is an extension of well-known linear trace element chromatography to the coupling of major elements and energy transport. Our analysis allows the prediction of the feedbacks that arise in reactive melt transport due to melting, freezing, dissolution and precipitation for frontal reactions. This study considers the simplified case of a rigid, partially molten porous medium with binary solid solution. As melt traverses a lithological contact-modeled as a Riemann problem-a rich set of features arise, including a reacted zone between an advancing reaction front and partial chemical preservation of the initial contact. Reactive instabilities observed in this study originate at the lithological interface rather than along a chemical gradient as in most studies of mantle dynamics. We present a regime diagram that predicts where reaction fronts become unstable, thereby allowing melt localization into high-porosity channels through reactive instabilities. After constructing the regime diagram, we test the one-dimensional hyperbolic theory against two-dimensional numerical experiments. The one-dimensional hyperbolic theory is sufficient for predicting the qualitative behavior of reactive melt transport simulations conducted in two-dimensions. The theoretical framework presented can be extended to more complex and realistic phase behavior, and is therefore a useful tool for understanding nonlinear feedbacks in reactive melt transport problems relevant to mantle dynamics.

Effective recovery of poly-β-hydroxybutyrate (PHB) biopolymer from Cupriavidus necator using a novel and environmentally friendly solvent system.

PubMed

Fei, Tao; Cazeneuve, Stacy; Wen, Zhiyou; Wu, Lei; Wang, Tong

2016-05-01

This work demonstrates a significant advance in bioprocessing for a high-melting lipid polymer. A novel and environmental friendly solvent mixture, acetone/ethanol/propylene carbonate (A/E/P, 1:1:1 v/v/v) was identified for extracting poly-hydroxybutyrate (PHB), a high-value biopolymer, from Cupriavidus necator. A set of solubility curves of PHB in various solvents was established. PHB recovery of 85% and purity of 92% were obtained from defatted dry biomass (DDB) using A/E/P. This solvent mixture is compatible with water, and from non-defatted wet biomass, PHB recovery of 83% and purity of 90% were achieved. Water and hexane were evaluated as anti-solvents to assist PHB precipitation, and hexane improved recovery of PHB from biomass to 92% and the purity to 93%. A scale-up extraction and separation reactor was designed, built and successfully tested. Properties of PHB recovered were not significantly affected by the extraction solvent and conditions, as shown by average molecular weight (1.4 × 10(6) ) and melting point (175.2°C) not being different from PHB extracted using chloroform. Therefore, this biorenewable solvent system was effective and versatile for extracting PHB biopolymers. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:678-685, 2016. © 2016 American Institute of Chemical Engineers.

Electrochemical extraction of neodymium by co-reduction with aluminum in LiCl-KCl molten salt

NASA Astrophysics Data System (ADS)

Yan, Yong-De; Xu, Yan-Lu; Zhang, Mi-Lin; Xue, Yun; Han, Wei; Huang, Ying; Chen, Qiong; Zhang, Zhi-Jian

2013-02-01

The electrochemical behavior of Nd(III) ions in LiCl-KCl and LiCl-KCl-AlCl3 melts on a Mo electrode at 723 K was studied by various electrochemical techniques. The results showed that Nd(III) ions are reduced to Nd(0) through two consecutive steps, and the underpotential deposition of neodymium on pre-deposited Al electrode formed two kinds of Al-Nd intermetallic compounds in LiCl-KCl-AlCl3 solutions. The electrochemical extraction of neodymium was carried out in LiCl-KCl-AlCl3 melts on a Mo electrode at 873 K by potentiostatic and galvanostatic electrolysis. The extraction efficiency was 99.25% after potentiostatic electrolysis for 30 h. Al-Li-Nd bulk alloy was obtained by galvanostatic electrolysis. X-ray diffraction (XRD) suggested that Al2Nd and Al3Nd phases were formed in Al-Li-Nd alloy. The microstructure and micro-zone chemical analysis of Al-Li-Nd alloy were characterized by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), respectively.

SEPARATION OF CURIUM AND AMERICIUM

DOEpatents

Fields, P.R.; Isaac, N.M.

1962-02-20

Curium and americium are contained in an anhydrous molten salt medium having a low melting point. Curium is preferentially extracted from the molten salt by a hot organic solvent containing preferably less than 10% alkyl phosphate. (AEC)

Hydrogen-alkali exchange between silicate melts and two-phase aqueous mixtures: an experimental investigation

NASA Astrophysics Data System (ADS)

Williams, Thomas J.; Candela, Philip A.; Piccoli, Philip M.

Experiments were performed in the three-phase system high-silica rhyolite melt + low-salinity aqueous vapor + hydrosaline brine, to investigate the exchange equilibria for hydrogen, potassium, and sodium in magmatic-hydrothermal systems at 800 °C and 100 MPa, and 850 °C and 50 MPa. The Kaqm/meltH,Na and Kaqm/meltH,K for hydrogen-sodium exchange between a vapor + brine mixture and a silicate melt are inversely proportional to the total chloride concentration (ΣCl) in the vapor + brine mixture indicating that HCl/NaCl and HCl/KCl are higher in the low-salinity aqueous vapor relative to high-salinity brine. The equilibrium constants for vapor/melt and brine/melt exchange were extracted from regressions of Kaqm/meltH,Na and Kaqm/meltH,K versus the proportion of aqueous vapor relative to brine in the aqueous mixture (Faqv) at P and T, expressed as a function of ΣCl. No significant pressure effect on the empirically determined exchange constants was observed for the range of pressures investigated. Model equilibrium constants are: Kaqv/meltH,Na(vapor/melt)=26(+/-1.3) at 100 MPa (800 °C), and 19( +/- 7.0) at 50 MPa (850 °C) Kaqv/meltH,K=14(+/-1.1) at 100 MPa (800 °C), and 24(+/-12) at 50 MPa (850 °C) Kaqb/meltH,b(brine/melt)= 1.6(+/-0.7) at 100 MPa (800 °C), and 3.9(+/-2.3) at 50 MPa (850 °C) and Kaqb/meltH,K=2.7(+/-1.2) at 100 MPa (800 °C) and 3.8(+/-2.3) at 50 MPa (850 °C). Values for Kaqv/meltH,K and Kaqb/meltH,K were used to calculate KCl/HCl in the aqueous vapor and brine as a function of melt aluminum saturation index (ASI: molar Al2O3/(K2O+Na2O+CaO) and pressure. The model log KCl/HCl values show that a change in melt ASI from peraluminous (ASI = 1.04) to moderately metaluminous (ASI = 1.01) shifts the cooling pathway (in temperature-log KCl/HCl space) of the aqueous vapor toward the andalusite+muscovite+K-feldspar reaction point.

Capabilities and limitations of dispersive liquid-liquid microextraction with solidification of floating organic drop for the extraction of organic pollutants from water samples.

PubMed

Vera-Avila, Luz E; Rojo-Portillo, Tania; Covarrubias-Herrera, Rosario; Peña-Alvarez, Araceli

2013-12-17

Dispersive liquid-liquid microextraction with solidification of floating organic drop (DLLME-SFO) is one of the most interesting sample preparation techniques developed in recent years. Although several applications have been reported, the potentiality and limitations of this simple and rapid extraction technique have not been made sufficiently explicit. In this work, the extraction efficiency of DLLME-SFO for pollutants from different chemical families was determined. Studied compounds include: 10 polycyclic aromatic hydrocarbons, 5 pesticides (chlorophenoxy herbicides and DDT), 8 phenols and 6 sulfonamides, thus, covering a large range of polarity and hydrophobicity (LogKow 0-7, overall). After optimization of extraction conditions using 1-dodecanol as extractant, the procedure was applied for extraction of each family from 10-mL spiked water samples, only adjusting sample pH as required. Absolute recoveries for pollutants with LogKow 3-7 were >70% and recovery values within this group (18 compounds) were independent of structure or hydrophobicity; the precision of recovery was very acceptable (RSD<12%) and linear behavior was observed in the studied concentration range (r(2)>0.995). Extraction recoveries for pollutants with LogKow 1.46-2.8 were in the range 13-62%, directly depending on individual LogKow values; however, good linearity (r(2)>0.993) and precision (RSD<6.5%) were also demonstrated for these polar solutes, despite recovery level. DLLME-SFO with 1-dodecanol completely failed for extraction of compounds with LogKow≤1 (sulfa drugs), other more polar extraction solvents (ionic liquids) should be explored for highly hydrophilic pollutants. Copyright © 2013 Elsevier B.V. All rights reserved.

Highly Sensitive Detection of Isoniazid Heteroresistance in Mycobacterium tuberculosis by DeepMelt Assay.

PubMed

Liang, Bin; Tan, Yaoju; Li, Zi; Tian, Xueshan; Du, Chen; Li, Hui; Li, Guoli; Yao, Xiangyang; Wang, Zhongan; Xu, Ye; Li, Qingge

2018-02-01

Detection of heteroresistance of Mycobacterium tuberculosis remains challenging using current genotypic drug susceptibility testing methods. Here, we described a melting curve analysis-based approach, termed DeepMelt, that can detect less-abundant mutants through selective clamping of the wild type in mixed populations. The singleplex DeepMelt assay detected 0.01% katG S315T in 10 5 M. tuberculosis genomes/μl. The multiplex DeepMelt TB/INH detected 1% of mutant species in the four loci associated with isoniazid resistance in 10 4 M. tuberculosis genomes/μl. The DeepMelt TB/INH assay was tested on a panel of DNA extracted from 602 precharacterized clinical isolates. Using the 1% proportion method as the gold standard, the sensitivity was found to be increased from 93.6% (176/188, 95% confidence interval [CI] = 89.2 to 96.3%) to 95.7% (180/188, 95% CI = 91.8 to 97.8%) compared to the MeltPro TB/INH assay. Further evaluation of 109 smear-positive sputum specimens increased the sensitivity from 83.3% (20/24, 95% CI = 64.2 to 93.3%) to 91.7% (22/24, 95% CI = 74.2 to 97.7%). In both cases, the specificity remained nearly unchanged. All heteroresistant samples newly identified by the DeepMelt TB/INH assay were confirmed by DNA sequencing and even partially by digital PCR. The DeepMelt assay may fill the gap between current genotypic and phenotypic drug susceptibility testing for detecting drug-resistant tuberculosis patients. Copyright © 2018 American Society for Microbiology.

Experimental study on latent heat storage characteristics of W/O emulsion -Supercooling rate of dispersed water drops by direct contact heat exchange-

NASA Astrophysics Data System (ADS)

Morita, Shin-ichi; Hayamizu, Yasutaka; Horibe, Akihiko; Haruki, Naoto; Inaba, Hideo

2013-04-01

Recently, much attention has been paid to investigate the latent heat storage system. Using of ice heat storage system brings an equalization of electric power demand, because it will solved the electric -power-demand-concentration on day-time of summer by the air conditioning. The flowable latent heat storage material, Oil/Water type emulsion, microencapsulated latent heat material-water mixture or ice slurry, etc., is enable to transport the latent heat in a pipe. The flowable latent heat storage material can realize the pipe size reduction and system efficiency improvement. Supercooling phenomenon of the dispersed latent heat storage material in continuous phase brings the obstruction of latent heat storage. The latent heat storage rates of dispersed water drops in W/O (Water/Oil) emulsion are investigated experimentally in this study. The water drops in emulsion has the diameter within 3 ˜ 25μm, the averaged water drop diameter is 7.3μm and the standard deviation is 2.9μm. The direct contact heat exchange method is chosen as the phase change rate evaluation of water drops in W/O emulsion. The supercooled temperature and the cooling rate are set as parameters of this study. The evaluation is performed by comparison between the results of this study and the past research. The obtained experimental result is shown that the 35K or more degree from melting point brings 100% latent heat storage rate of W/O emulsion. It was clarified that the supercooling rate of dispersed water particles in emulsion shows the larger value than that of the bulk water.

Evaluating Light Rain Drop Size Estimates from Multiwavelength Micropulse Lidar Network Profiling

NASA Technical Reports Server (NTRS)

Lolli, Simone; Welton, Ellsworth J.; Campbell, James R.

2013-01-01

This paper investigates multiwavelength retrievals of median equivolumetric drop diameter D(sub 0) suitable for drizzle and light rain, through collocated 355-/527-nm Micropulse Lidar Network (MPLNET) observations collected during precipitation occurring 9 May 2012 at the Goddard Space Flight Center (GSFC) project site. By applying a previously developed retrieval technique for infrared bands, the method exploits the differential backscatter by liquid water at 355 and 527 nm for water drops larger than approximately 50 micrometers. In the absence of molecular and aerosol scattering and neglecting any transmission losses, the ratio of the backscattering profiles at the two wavelengths (355 and 527 nm), measured from light rain below the cloud melting layer, can be described as a color ratio, which is directly related to D(sub 0). The uncertainty associated with this method is related to the unknown shape of the drop size spectrum and to the measurement error. Molecular and aerosol scattering contributions and relative transmission losses due to the various atmospheric constituents should be evaluated to derive D(sub 0) from the observed color ratio profiles. This process is responsible for increasing the uncertainty in the retrieval. Multiple scattering, especially for UV lidar, is another source of error, but it exhibits lower overall uncertainty with respect to other identified error sources. It is found that the total error upper limit on D(sub 0) approaches 50%. The impact of this retrieval for long-term MPLNET monitoring and its global data archive is discussed.

Modeling Mantle Shear Zones, Melt Focusing and Stagnation - Are Non Volcanic Margins Really Magma Poor?

NASA Astrophysics Data System (ADS)

Lavier, L. L.; Muntener, O.

2011-12-01

Mantle peridotites from ocean-continent transition zones (OCT's) and ultraslow spreading ridges question the commonly held assumption of a simple link between mantle melting and MORB. 'Ancient' and partly refertilized mantle in rifts and ridges illustrates the distribution of the scale of upper mantle heterogeneity even on a local scale. Upwelling of partial melts that enter the conductive lithospheric mantle inevitably leads to freezing of the melt and metasomatized lithosphere. Field data and petrology demonstrates that ancient, thermally undisturbed, pyroxenite-veined subcontinental mantle blobs formed parts of the ocean floor next to thinned continental crust. Similar heterogeneity might be created in the oceanic lithosphere where the thermal boundary layer (TBM) is thick and veined with metasomatic assemblages. This cold, ancient, 'subcontinental domain' is separated by ductile shear zones (or some other form of permeability barriers) from an infiltrated ('hot') domain dominated by refertilized spinel and/or plagioclase peridotite. The footwall of these mantle shear zones display complex refertilization processes and high-temperature deformation. We present numerical models that illustrate the complex interplay of km-scale refertilization with active deformation and melt focusing on top of the mantle. Melt lubricated shear zones focus melt flow in shear fractures (melt bands) occurring along grain boundaries. Continuous uplift and cooling leads to crystallization, and crystal plastic deformation prevails in the subsolidus state. Below 800oC if water is present deformation by shearing of phyllosilicates may become prevalent. We develop physical boundary conditions for which stagnant melt beneath a permeability barrier remains trapped rather than being extracted to the surface via melt-filled fractures. We explore the parameter space for fracturing and drainage and development of anastomozing impermeable shear zones. Our models might be useful to constrain the conditions and enigmatic development of magma-poor and magma rich margins.

Production of anhydrous aluminum chloride composition

DOEpatents

Vandergrift, G.F. III; Krumpelt, M.; Horwitz, E.P.

1981-10-08

A process is described for producing an anhydrous aluminum chloride composition from a water-based aluminous material such as a slurry of aluminum hydroxide in a multistage extraction process in which the aluminum ion is first extracted into an organic liquid containing an acidic extractant and then extracted from the organic phase into an alkali metal chloride or chlorides to form a melt containing a mixture of chlorides of alkali metal and aluminum. In the process, the organic liquid may be recycled. In addition, the process advantageously includes an electrolysis cell for producing metallic aluminum and the alkali metal chloride or chlorides may be recycled for extraction of the aluminum from the organic phase.

Production of anhydrous aluminum chloride composition and process for electrolysis thereof

DOEpatents

Vandegrift, George F.; Krumpelt, Michael; Horwitz, E. Philip

1983-01-01

A process for producing an anhydrous aluminum chloride composition from a water-based aluminous material such as a slurry of aluminum hydroxide in a multistage extraction process in which the aluminum ion is first extracted into an organic liquid containing an acidic extractant and then extracted from the organic phase into an alkali metal chloride or chlorides to form a melt containing a mixture of chlorides of alkali metal and aluminum. In the process, the organic liquid may be recycled. In addition, the process advantageously includes an electrolysis cell for producing metallic aluminum and the alkali metal chloride or chlorides may be recycled for extraction of the aluminum from the organic phase.

Efficacy of naturopathic extracts in the management of ear pain associated with acute otitis media.

PubMed

Sarrell, E M; Mandelberg, A; Cohen, H A

2001-07-01

To determine the efficacy and tolerance of Otikon Otic Solution (Healthy-On Ltd, Petach-Tikva, Israel), a naturopathic herbal extract (containing Allium sativum, Verbascum thapsus, Calendula flores, and Hypericum perforatum in olive oil), compared with Anaesthetic (Vitamed Pharmaceutical Ltd, Benyamina, Israel) ear drops (containing ametocaine and phenazone in glycerin) in the management of ear pain associated with acute otitis media (AOM). Children between the ages of 6 and 18 years who experienced ear pain (otalgia) and who were diagnosed with eardrum problems associated with AOM were randomly assigned to be treated with Otikon or Anaesthetic ear drops, which were instilled into the external canal(s) of the affected ear(s). Ear pain was assessed using 2 visual analog scales: a linear scale and a color scale. Pain assessment took place throughout the course of 3 days. The mean score of pain reduction was used to measure outcome. Primary pediatric community ambulatory centers. One hundred three children aged 6 to 18 years who were diagnosed with otalgia associated with AOM. Each of the 2 treatment groups were comparable on the basis of age, sex, laterality of AOM, and the effectiveness of ameliorating symptoms of otalgia. The 2 groups were also comparable to each other in the initial ear pain score and in the scores at each application of Otikon or Anaesthetic drops. There was a statistically significant improvement in ear pain score throughout the course of the study period (P =.007). Otikon, an ear drop formulation of naturopathic origin, is as effective as Anaesthetic ear drops and was proven appropriate for the management of AOM-associated ear pain.

Viscous constitutive relations of solid-liquid composites in terms of grain boundary contiguity: 1. Grain boundary diffusion control model

NASA Astrophysics Data System (ADS)

Takei, Yasuko; Holtzman, Benjamin K.

2009-06-01

Viscous constitutive relations of partially molten rocks deforming in the regime of grain boundary (GB) diffusion creep are derived theoretically on the basis of microstructural processes at the grain scale. The viscous constitutive relation developed in this study is based on contiguity as an internal state variable, which enables us to take into account the detailed effects of grain-scale melt distribution observed in experiments. Compared to the elasticities derived previously for the same microstructural model, the viscosities are much more sensitive to the presence of melt and variations in contiguity. As explored in this series of three companion papers, this "contiguity" model predicts that a very small amount of melt (ϕ < 0.01) significantly reduces the bulk and shear viscosities. Furthermore, a large anisotropy in viscosity is produced by anisotropy in contiguity, which occurs in deforming partially molten rocks. These results have important implications for deformation and melt extraction at small melt fractions, as well as for shear-induced melt segregation. The viscous and elastic constitutive relations derived in terms of contiguity bridge microscopic grain-scale and macroscopic continuum properties. These constitutive relations are essential for investigating melt migration dynamics in a forward sense on the basis of the basic equations of two-phase dynamics and in an inverse sense on the basis of seismological observations.

Corneal crystalline deposits associated with topically applied gatifloxacin.

PubMed

Elia, Maxwell; Khodadadeh, Sarah; Chow, Jessica

2014-06-01

To report a case of corneal crystalline deposits from the use of gatifloxacin 0.5% topical antibiotic after combined cataract extraction and trabeculotomy ab interno surgery. A 59-year-old woman presented after combined cataract extraction and trabeculotomy ab interno with crystalline deposits in the anterior corneal stroma. Clinical examination and slit-lamp photography were performed. The slit-lamp examination showed inferior white crystal deposition in the anterior stroma with overlying punctate epithelial erosions 4 weeks postoperatively. The eye was asymptomatic, but the deposition was cosmetically noticeable to the patient. Serial slit-lamp photography demonstrated resolution of the crystalline deposits 30 days after the discontinuation of eye drops. The authors present a rare case of stromal crystallization from topical gatifloxacin treatment. Complete resolution of corneal deposits was seen 30 days after the discontinuation of the drops without sequelae.

Copper isotope fractionation during partial melting and melt percolation in the upper mantle: Evidence from massif peridotites in Ivrea-Verbano Zone, Italian Alps

NASA Astrophysics Data System (ADS)

Huang, Jian; Huang, Fang; Wang, Zaicong; Zhang, Xingchao; Yu, Huimin

2017-08-01

To investigate the behavior of Cu isotopes during partial melting and melt percolation in the mantle, we have analyzed Cu isotopic compositions of a suite of well-characterized Paleozoic peridotites from the Balmuccia and Baldissero massifs in the Ivrea-Verbano Zone (IVZ, Northern Italy). Our results show that fresh lherzolites and harzburgites have a large variation of δ65Cu ranging from -0.133 to 0.379‰, which are negatively correlated with Al2O3 contents as well as incompatible platinum-group (e.g., Pd) and chalcophile element (e.g., Cu, S, Se, and Te) contents. The high δ65Cu can be explained by Cu isotope fractionation during partial melting of a sulfide-bearing peridotite source, with the light isotope (63Cu) preferentially entering the melts. The low δ65Cu can be attributed to precipitation of sulfides enriched in 63Cu during sulfur-saturated melt percolation. Replacive dunites from the Balmuccia massif display high δ65Cu from 0.544 to 0.610‰ with lower Re, Pd, S, Se, and Te contents and lower Pd/Ir ratios relative to lherzolites, which may result from dissolution of sulfides during interactions between S-undersaturated melts and lherzolites at high melt/rock ratios. Thus, our results suggest that partial melting and melt percolation largely account for the Cu isotopic heterogeneity of the upper mantle. The correlation between δ65Cu and Cu contents of the lherzolites and harzburgites was used to model Cu isotope fractionation during partial melting of a sulfide-bearing peridotite, because Cu is predominantly hosted in sulfide. The modelling results indicate an isotope fractionation factor of αmelt-peridotite = 0.99980-0.99965 (i.e., 103lnαmelt-peridotite = -0.20 to -0.35‰). In order to explain the Cu isotopic systematics of komatiites and mid-ocean ridge basalts reported previously, the estimated αmelt-peridotite was used to simulate Cu isotopic variations in melts generated by variable degrees of mantle melting. The results suggest that high degrees (>25%) of partial melting extracts nearly all source Cu and it cannot produce Cu isotope fractionation in komatiites relative to their mantle source, and that sulfide segregation during magma evolution have modified Cu isotopic compositions of mid-ocean ridge basalts.

Extraction process for removing metallic impurities from alkalide metals

DOEpatents

Royer, L.T.

1987-03-20

A development is described for removing metallic impurities from alkali metals by employing an extraction process wherein the metallic impurities are extracted from a molten alkali metal into molten lithium metal due to the immiscibility of the alkali metals in lithium and the miscibility of the metallic contaminants or impurities in the lithium. The purified alkali metal may be readily separated from the contaminant-containing lithium metal by simple decanting due to the differences in densities and melting temperatures of the alkali metals as compared to lithium.

Signature of Arctic first-year ice melt pond fraction in X-band SAR imagery

NASA Astrophysics Data System (ADS)

Fors, Ane S.; Divine, Dmitry V.; Doulgeris, Anthony P.; Renner, Angelika H. H.; Gerland, Sebastian

2017-03-01

In this paper we investigate the potential of melt pond fraction retrieval from X-band polarimetric synthetic aperture radar (SAR) on drifting first-year sea ice. Melt pond fractions retrieved from a helicopter-borne camera system were compared to polarimetric features extracted from four dual-polarimetric X-band SAR scenes, revealing significant relationships. The correlations were strongly dependent on wind speed and SAR incidence angle. Co-polarisation ratio was found to be the most promising SAR feature for melt pond fraction estimation at intermediate wind speeds (6. 2 m s-1), with a Spearman's correlation coefficient of 0. 46. At low wind speeds (0. 6 m s-1), this relation disappeared due to low backscatter from the melt ponds, and backscatter VV-polarisation intensity had the strongest relationship to melt pond fraction with a correlation coefficient of -0. 53. To further investigate these relations, regression fits were made both for the intermediate (R2fit = 0. 21) and low (R2fit = 0. 26) wind case, and the fits were tested on the satellite scenes in the study. The regression fits gave good estimates of mean melt pond fraction for the full satellite scenes, with less than 4 % from a similar statistics derived from analysis of low-altitude imagery captured during helicopter ice-survey flights in the study area. A smoothing window of 51 × 51 pixels gave the best reproduction of the width of the melt pond fraction distribution. A considerable part of the backscatter signal was below the noise floor at SAR incidence angles above ˜ 40°, restricting the information gain from polarimetric features above this threshold. Compared to previous studies in C-band, limitations concerning wind speed and noise floor set stricter constraints on melt pond fraction retrieval in X-band. Despite this, our findings suggest new possibilities in melt pond fraction estimation from X-band SAR, opening for expanded monitoring of melt ponds during melt season in the future.

Analysis of Chromatin Organisation

ERIC Educational Resources Information Center

Szeberenyi, Jozsef

2011-01-01

Terms to be familiar with before you start to solve the test: chromatin, nucleases, sucrose density gradient centrifugation, melting point, gel electrophoresis, ethidium bromide, autoradiography, Southern blotting, Northern blotting, Sanger sequencing, restriction endonucleases, exonucleases, linker DNA, chloroform extraction, nucleosomes,…

Red-Sea rift magmatism near Al Lith, Kingdom of Saudi Arabia

USGS Publications Warehouse

Pallister, J.S.

1986-01-01

A model of poly-baric mantle-melt derivation, producing several alkalinesubalkaline cycles, best explains magmatism in the Red Sea region. Differences in the depths and dynamics of mantle-melt extraction and transport brought about through changes in crust and mantle structure as the rift and paar developed may account for the transition from mixed alkaline-subalkaline bimodal magmatism of the pre-20 Ma rift basin to exclusively subalkaline (tholeiitic) magmatism at the Red Sea spreading axis and to predominantly alkali basalt volcanism within the Arabian Shield.

Illustration of cross flow of polystyrene melts through a coathanger die

NASA Astrophysics Data System (ADS)

Schöppner, V.; Henke, B.

2015-05-01

To design an optimal coathanger die with a uniform flow rate distribution and low pressure drop, it is essential to understand the flow conditions in the die. This is important because the quality of the product is influenced by the flow velocity and the flow rate distribution. In extrusion dies, cross flows also occur in addition to the main flow, which flow perpendicular to the main flow. This results in pressure gradients in the extrusion direction, which have an influence on flow distribution and pressure drop in the die. In recent decades, quantitative representation and analysis of physical flow processes have made considerable progress in predicting the weather, developing drive technologies and designing aircraft using simulation methods and lab trials. Using the flow-line method, the flow is analyzed in flat film extrusion dies with a rectangular cross-section, in particular cross flows. The simplest method to visualize the flow is based on the measurement of obstacle orientation in the flow field by adding individual particles. A near-surface flow field can be visualized by using wool or textile yarns. By sticking thin, frayed at the ends of strands of wool surface that is to be examined cross flows, near-wall profiles of the flow and vortex and separation regions can be visualized. A further possibility is to add glass fibers and analyze the fiber orientation by microscopy and x-ray analysis. In this paper the influence of process parameters (e.g. melt temperatures and throughput) on cross flow and fiber orientation is described.

Influences of electric current on the wettability and interfacial microstructure in Sn/Fe system

NASA Astrophysics Data System (ADS)

Shen, Ping; Gu, Yan; Yang, Nan-Nan; Zheng, Rui-Peng; Ren, Li-Hua

2015-02-01

The wettability of oxidized and clean Fe substrates by liquid Sn was investigated using a dispensed sessile drop method with and without the application of a direct current (DC) and their interfacial microstructures were compared. The initial contact angles were 107 ± 3° at 623 K when the Fe substrate was covered by an oxide film, and they did not show an appreciable decrease during isothermal dwells in the absence of DC application but progressively decreased to 42 ± 3° when a 7.5 ampere current was applied. However, in the case of the oxide film being removed by a high-vacuum pre-annealing treatment at 1073 K, the current and its polarity had a negligible effect on the wetting behavior. Nevertheless, they had a noticeable influence on the interfacial microstructure. In the absence of DC, the interface was covered by a product layer consisting of a single FeSn2 phase for the samples tested at 623 K and the FeSn2/FeSn2 grain boundaries were incompletely wetted by the Sn melt; whereas, under DC, the reaction layer was much thicker and the Sn melt wet well the FeSn2/FeSn2 grain boundaries. Moreover, a FeSn phase also formed as a result of enhanced mass transfer. The amount of the FeSn phase was larger and the grain boundary wetting of FeSn2 by liquid Sn was better for the current flowing from the molten Sn drop to the Fe substrate due to an electromigration effect.

New Phenomena in High Temperature Nanofriction on Nonmelting Surfaces: NaCl(100)

NASA Astrophysics Data System (ADS)

Zykova-Timan, Tatyana; Ceresoli, Davide; Tosatti, Erio

2006-03-01

High temperature nanofriction is a difficult and so far unexplored area whwere we made an initial attack by means of simulation. Alkali halide (100) surfaces were chosen as they would not automatically liquefy under a sliding tip, even at temperatures very close to the melting point. We conducted sliding friction molecular dynamics simulations of hard tips on NaCl(100),both in the heavy ploughing, wear-dominated regime, and in the light grazing, wearless regime. Ploughing friction shows for increasing temperature a strong frictional drop near the melting point. Here the tip can be characterized as ``skating'' over the hot solid, its apex surrounded by a local liquid halo, which moves along with the tip as it ploughs on. At the opposite extreme, we find that grazing friction of a lightly pressed flat-ended tip behaves just the other way around. Starting with an initially very weak low temperature frictional force, there is a surge of friction just near the melting point, where the surface is still solid, but not too far from a vibrational instability. This frictional rise can be envisaged as an analog of the celebrated ``peak effect'' found close to Hc2 in the mixed state critical current of type II superconductors.

Measurement of Attenuation with Airborne and Ground-Based Radar in Convective Storms Over Land and Its Microphysical Implications

NASA Technical Reports Server (NTRS)

Tian, Lin; Heymsfield, G. M.; Srivastava, R. C.; Starr, D. OC. (Technical Monitor)

2001-01-01

Observations by the airborne X-band Doppler radar (EDOP) and the NCAR S-band polarimetric (S-POL) radar from two field experiments are used to evaluate the Surface ref'ercnce technique (SRT) for measuring the path integrated attenuation (PIA) and to study attenuation in deep convective storms. The EDOP, flying at an altitude of 20 km, uses a nadir beam and a forward pointing beam. It is found that over land, the surface scattering cross-section is highly variable at nadir incidence but relatively stable at forward incidence. It is concluded that measurement by the forward beam provides a viable technique for measuring PIA using the SRT. Vertical profiles of peak attenuation coefficient are derived in vxo deep convective storms by the dual-wavelength method. Using the measured Doppler velocity, the reflectivities at. the two wavelengths, the differential reflectivity and the estimated attenuation coefficients, it is shown that: supercooled drops and dry ice particles probably co-existed above the melting level in regions of updraft, that water-coated partially melted ice particles probably contributed to high attenuation below the melting level, and that the data are not readil explained in terms of a gamma function raindrop size distribution.

Oceanic Volcanism from the Low-Velocity Zone - Without Mantle Plumes (Invited)

NASA Astrophysics Data System (ADS)

Presnall, D. C.; Gudfinnsson, G. H.

2010-12-01

The existence of hot mantle plumes is addressed by using a combination of regional and global shear-wave data, major-element compositions of Hawaiian and MORB glasses (including Iceland), and phase relations for natural lherzolite and the systems CaO-MgO-Al2O3-SiO2-CO2 and CaO-MgO-Al2O3-SiO2-Na2O-FeO. At the East Pacific Rise, the depth of minimum shear wave velocity (Vsv), which we interpret to be the depth of maximum melting, occurs at ~65 km (Webb & Forsyth, 1998, Science, 280, 1229; Conder et al., 2002, JGR, 107, 2344)). This depth increases with lithospheric age and stabilizes at ~150 km (~5 GPa) for ages > ~75 my (Maggi et al., 2006, GJI, 166, 1384). Variations in shear wave anisotropy follow the same pattern (Ekström, 2000, Geophys. Mon. 121, 239) but with a slightly shallower depth of ~130 km for the maximum shear wave anisotropy of the mature Pacific. For a given volcano, the classical Hawaiian sequence of volcanism is early alkalic lavas extracted at ~3 GPa, 1350°C (Sisson et al., 2009, CMP, 158, 803), then voluminous tholeiitic lavas at ~ 4-5 GPa, 1450-1560°C (~150 km), and final alkalic lavas that contain, on Oahu, nanodiamond-bearing xenoliths (Wirth & Rocholl, 2003, EPSL, 211, 357; Frezotti & Peccerillo, 2007, EPSL, 262, 273) and require melt extraction at a pressure slightly > 6 GPa. This progressive increase in P-T conditions of the Hawaiian source matches the equilibrium magma-stratigraphy vs depth indicated by phase relations along a mature-ocean geotherm. This consistency indicates that Hawaiian volcanism occurs by progressively deeper extraction of magmas from a mature LVZ by fracturing of the overlying LID. No decompression melting or enhanced temperature is indicated. At spreading ridges, including Iceland, the absence of glass compositions that define olivine-controlled crystallization trends and the phase equilibrium constraint that all MORBs are extracted at ~1250-1280°C, 1.2-1.5 GPa (Presnall & Gudfinnsson, 2008, JPet., 49, 615) are in excellent agreement with the seismic observation of minimum shear-wave velocity and maximum shear-wave anisotropy (maximum melting) beneath ridges at ~ 65 km. Thus, all MORBs, including those at Iceland, are extracted within the thermal boundary layer along a perturbed geotherm at temperatures cooler than magma-extraction temperatures at Hawaii. This requires a steepened dT/dP slope of the conductive portion of the geotherm at ridges, which is consistent with oceanic heat-flow data vs crustal age. Mantle temperatures for the strongest plume candidate, Hawaii, are consistent with temperatures of oceanic mantle elsewhere of a corresponding age. Temperatures of magma-extraction along all oceanic ridges are far below temperatures consistent with hot mantle plumes.

Optimization of plasma parameters with magnetic filter field and pressure to maximize H{sup −} ion density in a negative hydrogen ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Won-Hwi; Dang, Jeong-Jeung; Kim, June Young

2016-02-15

Transverse magnetic filter field as well as operating pressure is considered to be an important control knob to enhance negative hydrogen ion production via plasma parameter optimization in volume-produced negative hydrogen ion sources. Stronger filter field to reduce electron temperature sufficiently in the extraction region is favorable, but generally known to be limited by electron density drop near the extraction region. In this study, unexpected electron density increase instead of density drop is observed in front of the extraction region when the applied transverse filter field increases monotonically toward the extraction aperture. Measurements of plasma parameters with a movable Langmuirmore » probe indicate that the increased electron density may be caused by low energy electron accumulation in the filter region decreasing perpendicular diffusion coefficients across the increasing filter field. Negative hydrogen ion populations are estimated from the measured profiles of electron temperatures and densities and confirmed to be consistent with laser photo-detachment measurements of the H{sup −} populations for various filter field strengths and pressures. Enhanced H{sup −} population near the extraction region due to the increased low energy electrons in the filter region may be utilized to increase negative hydrogen beam currents by moving the extraction position accordingly. This new finding can be used to design efficient H{sup −} sources with an optimal filtering system by maximizing high energy electron filtering while keeping low energy electrons available in the extraction region.« less

Membraneless organelles can melt nucleic acid duplexes and act as biomolecular filters

NASA Astrophysics Data System (ADS)

Nott, Timothy J.; Craggs, Timothy D.; Baldwin, Andrew J.

2016-06-01

Membraneless organelles are cellular compartments made from drops of liquid protein inside a cell. These compartments assemble via the phase separation of disordered regions of proteins in response to changes in the cellular environment and the cell cycle. Here we demonstrate that the solvent environment within the interior of these cellular bodies behaves more like an organic solvent than like water. One of the most-stable biological structures known, the DNA double helix, can be melted once inside the liquid droplet, and simultaneously structures formed from regulatory single-stranded nucleic acids are stabilized. Moreover, proteins are shown to have a wide range of absorption or exclusion from these bodies, and can act as importers for otherwise-excluded nucleic acids, which suggests the existence of a protein-mediated trafficking system. A common strategy in organic chemistry is to utilize different solvents to influence the behaviour of molecules and reactions. These results reveal that cells have also evolved this capability by exploiting the interiors of membraneless organelles.

High Power Laser Beam Welding of Thick-walled Ferromagnetic Steels with Electromagnetic Weld Pool Support

NASA Astrophysics Data System (ADS)

Fritzsche, André; Avilov, Vjaceslav; Gumenyuk, Andrey; Hilgenberg, Kai; Rethmeier, Michael

The development of modern high power laser systems allows single pass welding of thick-walled components with minimal distortion. Besides the high demands on the joint preparation, the hydrostatic pressure in the melt pool increases with higher plate thicknesses. Reaching or exceeding the Laplace pressure, drop-out or melt sagging are caused. A contactless electromagnetic weld support system was used for laser beam welding of thick ferromagnetic steel plates compensating these effects. An oscillating magnetic field induces eddy currents in the weld pool which generate Lorentz forces counteracting the gravity forces. Hysteresis effects of ferromagnetic steels are considered as well as the loss of magnetization in zones exceeding the Curie temperature. These phenomena reduce the effective Lorentz forces within the weld pool. The successful compensation of the hydrostatic pressure was demonstrated on up to 20 mm thick plates of duplex and mild steel by a variation of the electromagnetic power level and the oscillation frequency.

MSFC Electrostatic Levitator (ESL) Rapid Quench System

NASA Technical Reports Server (NTRS)

SanSoucie, Michael P.; Craven, Paul D.; Rogers, Jan R.

2014-01-01

The NASA Marshall Space Flight Center (MSFC) Electrostatic Levitator (ESL) Laboratory is a unique facility for investigators studying high-temperature materials. The laboratory boasts two levitators in which samples can be levitated, heated, melted, undercooled, and resolidified, all without the interference of a container or data-gathering instrument. The ESL main chamber has been upgraded with the addition of a rapid quench system. This system allows samples to be dropped into a quench vessel that can be filled with a low melting point material, such as a gallium or indium alloy. Thereby allowing rapid quenching of undercooled liquid metals. Up to 8 quench vessels can be loaded into the quench wheel, which is indexed with LabVIEW control software. This allows up to 8 samples to be rapidly quenched before having to open the chamber. The system has been tested successfully on several zirconium samples. Future work will be done with other materials using different quench mediums. Microstructural analysis will also be done on successfully quench samples.

SEM and AFM Studies of Two-Phase Magnetic Alkali Borosilicate Glasses

PubMed Central

Tomkovich, M.; Nacke, B.; Filimonov, A.; Alekseeva, O.; Vanina, P.; Nizhankovskii, V.

2017-01-01

The morphology and composition of four types of two-phase alkali borosilicate glasses with magnetic atoms prepared by inductive melting have been studied. The results of scanning electron microscopy point to uniform distribution of Na, Si, and O atoms in these samples while magnetic iron atoms form ball-shaped agglomerates. The magnetic properties of these agglomerates have been confirmed by magnetic force microscopy. Atomic force microscopy had shown that in these samples two different morphological structures, drop-like and dendrite net, are formed. The formation of dendrite-like structure is a necessary condition for production of porous magnetic glasses. The obtained results allow us to optimize the melting and heat treatment processes leading to production of porous alkali borosilicate glasses with magnetic properties. The first results for nanocomposite materials on the basis of magnetic glasses containing the embedded ferroelectrics KH2PO4 demonstrate the effect of applied magnetic field on the ferroelectric phase transition. PMID:28428976

Research study on materials processing in space experiment number M512. [adhesion-cohesion properties of liquid metals under weightlessness conditions in Skylab

NASA Technical Reports Server (NTRS)

Tobin, J. M.; Kossowsky, R.

1973-01-01

Adhesion of the melted metals to the adjacent solid metals, and cohesion of the liquid metal to itself appeared to be equally as strong in zero gravity as on earth. Similar cut edge bead periodicity in cut thin plate, and similar periodic chevron patterns in full penetration welds were seen. The most significant practical result is that the design of braze joints for near zero gravity can be very tolerant of dimensional gaps in the joint. This conclusion is based on a comparison of narrow, wide and variable gap widths. Brazing is very practical as a joining or repairing technique for metal structures at zero gravity. The operation of the hardware developed to locate successive small (0.6 cm) diameter cylinders in the focus of the battery powered EB unit, melt the various metal specimens and deploy some liquid metal drops to drift in space, was generally successful. However, the sphericity and surface roughness were far from those of ball bearings.

Multiscale Behavior of Viscous Fluids Dynamics: Experimental Observations

NASA Astrophysics Data System (ADS)

Arciniega-Ceballos, Alejandra; Spina, Laura; Scheu, Bettina; Dingwell, Donald B.

2016-04-01

The dynamics of Newtonian fluids with viscosities of mafic to intermediate silicate melts (10-1000 Pa s) during slow decompression present multi-time scale processes. To observe these processes we have performed several experiments on silicon oil saturated with Argon gas for 72 hours, in a Plexiglas autoclave. The slow decompression, dropping from 10 MPa to ambient pressure, acting as the excitation mechanism, triggered several processes with their own distinct timescales. These processes generate complex non-stationary microseismic signals, which have been recorded with 7 high-dynamic piezoelectric sensors located along the conduit flanked by high-speed video recordings. The analysis in time and frequency of these time series and their correlation with the associated high-speed imaging enables the characterization of distinct phases and the extraction of the individual processes during the evolution of decompression of these viscous fluids. We have observed fluid-solid elastic interaction, degassing, fluid mass expansion and flow, bubble nucleation, growth, coalescence and collapse, foam building and vertical wagging. All these processes (in fine and coarse scales) are sequentially coupled in time, occur within specific pressure intervals, and exhibit a localized distribution along the conduit. Their coexistence and interactions constitute the stress field and driving forces that determine the dynamics of the conduit system. Our observations point to the great potential of this experimental approach in the understanding of volcanic conduit dynamics and volcanic seismicity.

Jing and King Receive Mineral and Rock Physics Graduate Research Awards

NASA Astrophysics Data System (ADS)

Anonymous

2012-02-01

Zhicheng Jing and Daniel King have been awarded the 2011 Mineral and Rock Physics Graduate Research Award, given annually to one or more promising young scientists for outstanding contributions achieved during their Ph.D. research. Recipients of this award are engaged in experimental and/or theoretical studies of Earth and planetary materials with the purpose of unraveling the physics and chemistry that govern their origin and physical properties. Jing's thesis is entitled "Equation of state of silicate liquids." King's thesis is entitled "Stress-driven melt segregation and reactive melt infiltration in partially molten rocks deformed in torsion with applications to melt extraction from Earth's mantle." They both were formally presented with the award at the 2011 AGU Fall Meeting, held 5-9 December in San Francisco, Calif.

Jing and King Receive Mineral and Rock Physics Graduate Research Awards

NASA Astrophysics Data System (ADS)

2012-02-01

Zhicheng Jing and Daniel King have been awarded the 2011 Mineral and Rock Physics Graduate Research Award, given annually to one or more promising young scientists for outstanding contributions achieved during their Ph.D. research. Recipients of this award are engaged in experimental and/or theoretical studies of Earth and planetary materials with the purpose of unraveling the physics and chemistry that govern their origin and physical properties. Jing's thesis is entitled “Equation of state of silicate liquids.” King's thesis is entitled “Stress-driven melt segregation and reactive melt infiltration in partially molten rocks deformed in torsion with applications to melt extraction from Earth's mantle.” They both were formally presented with the award at the 2011 AGU Fall Meeting, held 5-9 December in San Francisco, Calif.

Torque Transient of Magnetically Drive Flow for Viscosity Measurement

NASA Technical Reports Server (NTRS)

Ban, Heng; Li, Chao; Su, Ching-Hua; Lin, Bochuan; Scripa, Rosalia N.; Lehoczky, Sandor L.

2004-01-01

Viscosity is a good indicator of structural changes for complex liquids, such as semiconductor melts with chain or ring structures. This paper discusses the theoretical and experimental results of the transient torque technique for non-intrusive viscosity measurement. Such a technique is essential for the high temperature viscosity measurement of high pressure and toxic semiconductor melts. In this paper, our previous work on oscillating cup technique was expanded to the transient process of a magnetically driven melt flow in a damped oscillation system. Based on the analytical solution for the fluid flow and cup oscillation, a semi-empirical model was established to extract the fluid viscosity. The analytical and experimental results indicated that such a technique has the advantage of short measurement time and straight forward data analysis procedures

Sensitive determination of cadmium using solidified floating organic drop microextraction-slotted quartz tube-flame atomic absorption spectroscopy.

PubMed

Akkaya, Erhan; Chormey, Dotse Selali; Bakırdere, Sezgin

2017-09-20

In this study, solidified floating organic drop microextraction (SFODME) by 1-undecanol was combined with slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS) for the determination of cadmium at trace levels. Formation of a complex with 4,4'-dimethyl-2,2'-bipyridine facilitated the extraction of cadmium from aqueous solutions. Several chemical variables were optimized in order to obtain high extraction outputs. Parameters such as concentration of the ligand, pH, and amount of buffer solution were optimized to enhance the formation of cadmium complex. The SFODME method was assisted by dispersion of extractor solvent into aqueous solutions using 2-propanol. Under the optimum extraction and instrumental conditions, the limit of detection and limit of quantitation values obtained for cadmium using the combined methods (SFODME-SQT-FAAS) were found to be 0.4 and 1.3 μg L -1 , respectively. Matrix effects on the method were also examined for tap water and wastewater, and spiked recovery results were found to be very satisfactory. Graphical Abstract SFODME-SQT-FAAS system for sensitive determination of cadmium.

Preconcentration of valsartan by dispersive liquid-liquid microextraction based on solidification of floating organic drop and its determination in urine sample: Central composite design.

PubMed

Pebdani, Arezou Amiri; Shabani, Ali Mohammad Haji; Dadfarnia, Shayesteh; Talebianpoor, Mohammad Sharif; Khodadoust, Saeid

2016-05-01

In this work, a fast, easy, and efficient dispersive liquid-liquid microextraction method based on solidification of floating organic drop followed by high-performance liquid chromatography with UV detection was developed for the separation/preconcentration and determination of the drug valsartan. Experimental design was applied for the optimization of the effective variables (such as volume of extracting and dispersing solvents, ionic strength, and pH) on the extraction efficiency of valsartan from urine samples. The optimized values were 250.0 μL ethanol, 65.0 μL 1-dodecanol, 4.0% w/v NaCl, pH 3.8, 1.0 min extraction time, and 4.0 min centrifugation at 4000 rpm min(-1) . The linear response (r(2) = 0.997) was obtained in the range of 0.013-10.0 μg mL(-1) with a limit of detection of 4.0 ng mL(-1) and relative standard deviations of less than 5.0 % (n = 6). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Melter Feed Reactions at T ≤ 700°C for Nuclear Waste Vitrification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Kai; Hrma, Pavel R.; Rice, Jarrett A.

2015-07-23

Batch reactions and phase transitions in a nuclear waste feed heated at 5 K min-1 up to 600°C were investigated by optical microscopy, scanning electron microscopy with energy dispersive X-ray spectrometer, and X-ray diffraction. Quenched samples were leached in deionized water at room temperature and 80°C to extract soluble salts and early glass-forming melt, respectively. To determine the content and composition of leachable phases, the leachates were analyzed by the inductively-coupled plasma spectroscopy. By ~400°C, gibbsite and borax lost water and converted to amorphous and intermediate crystalline phases. Between 400°C and 600°C, the sodium borate early glass-forming melt reacted withmore » amorphous aluminum oxide and calcium oxide to form intermediate products containing Al and Ca. At ~600°C, half Na and B converted to the early glass-forming melt, and quartz began to dissolve in the melt.« less

Thermal Property Measurement of Semiconductor Melt using Modified Laser Flash Method

NASA Technical Reports Server (NTRS)

Lin, Bochuan; Zhu, Shen; Ban, Heng; Li, Chao; Scripa, Rosalla N.; Su, Ching-Hua; Lehoczky, Sandor L.

2003-01-01

This study further developed standard laser flash method to measure multiple thermal properties of semiconductor melts. The modified method can determine thermal diffusivity, thermal conductivity, and specific heat capacity of the melt simultaneously. The transient heat transfer process in the melt and its quartz container was numerically studied in detail. A fitting procedure based on numerical simulation results and the least root-mean-square error fitting to the experimental data was used to extract the values of specific heat capacity, thermal conductivity and thermal diffusivity. This modified method is a step forward from the standard laser flash method, which is usually used to measure thermal diffusivity of solids. The result for tellurium (Te) at 873 K: specific heat capacity 300.2 Joules per kilogram K, thermal conductivity 3.50 Watts per meter K, thermal diffusivity 2.04 x 10(exp -6) square meters per second, are within the range reported in literature. The uncertainty analysis showed the quantitative effect of sample geometry, transient temperature measured, and the energy of the laser pulse.

Cluster Morphology-Polymer Dynamics Correlations in Sulfonated Polystyrene Melts: Computational Study

DOE PAGES

Agrawal, Anupriya; Perahia, Dvora; Grest, Gary S.

2016-04-11

Reaching exceptionally long times up to 500 ns in equilibrium and nonequilibrium molecular dynamics simulations studies, we have attained a fundamental molecular understanding of the correlation of ionomer clusters structure and multiscale dynamics, providing new insight into one critical, long-standing challenge in ionic polymer physics. The cluster structure in melts of sulfonated polystyrene with Na + and Mg 2+ counterions are resolved and correlated with the dynamics on multiple length and time scales extracted from measurements of the dynamic structure factor and shear rheology. We find that as the morphology of the ionic clusters changes from ladderlike for Na +more » to disordered structures for Mg 2+, the dynamic structure factor is affected on the length scale corresponding to the ionic clusters. Lastly, rheology studies show that the viscosity for Mg 2+ melts is higher than for Na + ones for all shear rates, which is well correlated with the larger ionic clusters’ size for the Mg 2+ melts.« less

Effect of Psidium cattleianum leaf extract on enamel demineralisation and dental biofilm composition in situ.

PubMed

Brighenti, Fernanda Lourenção; Gaetti-Jardim, Elerson; Danelon, Marcelle; Evangelista, Gustavo Vaz; Delbem, Alberto Carlos Botazzo

2012-08-01

Previous evaluations of Psidium cattleianum leaf extract were not done in conditions similar to the oral environment. The aim of this study was to evaluate the effect of P. cattleianum leaf extract on enamel demineralisation, extracellular polysaccharide formation, and the microbial composition of dental biofilms formed in situ. Ten volunteers took part in this crossover study. They wore palatal appliances containing 4 enamel blocks for 14 days. Each volunteer dripped 20% sucrose 8 times per day on the enamel blocks. Twice a day, deionised water (negative control), extract, or a commercial mouthwash (active control) was dripped after sucrose application. On the 12th and 13th days of the experiment, plaque acidogenicity was measured with a microelectrode, and the pH drop was calculated. On the 14th day, biofilms were harvested and total anaerobic microorganisms (TM), total streptococci (TS), mutans streptococci (MS), and extracellular polysaccharides (EPS) were evaluated. Enamel demineralisation was evaluated by the percentage change of surface microhardness (%ΔSMH) and integrated loss of subsurface hardness (ΔKHN). The researcher was blinded to the treatments during data collection. The extract group showed lower TM, TS, MS, EPS, %ΔSMH, and ΔKHN values than the negative control group. There were no differences between the active and negative control groups regarding MS and EPS levels. There were no differences in pH drop between the extract and active control groups, although they were significantly different from the negative control group. For all other parameters, the extract differed from the active control group. Psidium cattleianum leaf extract exhibits a potential anticariogenic effect. Copyright © 2012 Elsevier Ltd. All rights reserved.

A numerical study on electrochemical transport of ions in calcium fluoride slag

NASA Astrophysics Data System (ADS)

Karimi-Sibaki, E.; Kharicha, A.; Wu, M.; Ludwig, A.

2016-07-01

Electrically resistive CaF 2-based slags are widely used in electroslag remelting (ESR) process to generate Joule heat for the melting of electrode. The electric current is conducted by ions (electrolyte) such as Ca +2 or F -, thus it is necessary to establish electrochemical models to study electrical behavior of slag. This paper presents a numerical model on electrochemical transport of ions in an arbitrary symmetrical (ZZ) and non-symmetrical (CaF2) stagnant electrolytes blocked by two parallel, planar electrodes. The dimensionless Poisson-Nernst-Planck (PNP) equations are solved to model electro-migration and diffusion of ions. The ions are considered to be inert that no Faradic reactions occur. Spatial variations of concentrations of ions, charge density and electric potential across the electrolyte are analyzed. It is shown that the applied potential has significant influence on the system response. At high applied voltage, the anodic potential drop near the electrode is significantly larger than cathodic potential drop in fully dissociated CaF2 electrolyte.

Direct printing of miniscule aluminum alloy droplets and 3D structures by StarJet technology

NASA Astrophysics Data System (ADS)

Gerdes, B.; Zengerle, R.; Koltay, P.; Riegger, L.

2018-07-01

Drop-on demand printing of molten metal droplets could be used for prototyping 3D objects as a promising alternative to laser melting technologies. However, to date, only few printheads have been investigated for this purpose, and they used only a limited range of materials. The pneumatically actuated StarJet technology enables the direct and non-contact printing of molten metal microdroplets from metal melts at high temperatures. StarJet printheads utilize nozzle chips featuring a star-shaped orifice geometry that leads to formation of droplets inside the nozzle with high precision. In this paper, we present a novel StarJet printhead for printing aluminum (Al) alloys featuring a hybrid design with a ceramic reservoir for the molten metal and an outer shell fabricated from stainless steel. The micro machined nozzle chip is made from silicon carbide (SiC). This printhead can be operated at up to 950 °C, and is capable of printing high melting point metals like Al alloys in standard laboratory conditions. In this work, an aluminum–silicon alloy that features 12% silicon (AlSi12) is printed. The printhead, nozzle, and peripheral actuation system are optimized for stable generation of AlSi12 droplets with high monodispersity, low angular deviation, and miniaturized droplet diameters. As a result, a stable drop-on-demand printing of droplets exhibiting diameters of d droplet  =  702 µm  ±  1% is demonstrated at 5 Hz with a low angular deviation of 0.3°, when a nozzle chip with 500 µm orifice diameter is used. Furthermore, AlSi12 droplets featuring d droplet  =  176 µm  ±  7% are printed when using a nozzle chip with an orifice diameter of 130 µm. Moreover, we present directly printed objects from molten Al alloy droplets, such as high aspect ratio, free-standing walls (aspect ratio 12:1), and directly printed, flexible springs, to demonstrate the principle of 3D printing with molten metal droplets.

The Merensky Reef in the Chineisky Pluton (Siberia)? A myth or a reality?

NASA Astrophysics Data System (ADS)

Zhitova, L.; Sharapov, V.; Zhukova, I.

2006-12-01

It is a dream of each geologist to find a `Merensky Reef' in each layered basic intrusion. Scientists have been trying many various techniques to come this dream to reality. The most perspective way to do so is probably a combination of physicochemical and computer modeling of layered basic intrusion crystallization together with fluid and melt inclusions studies in situ. This combination allows us to do the following: 1. To study boundary conditions for separation of low density gas phase and salt melt from the crystallizing primary basic melt in large magma chamber. 2. To determine correct quantitative parameters for formation of residual fluid-bearing brines extracting high metal concentrations. 3. To compute critical levels for substance differentiation at phase, geochemical and other `barriers' in those basic mantle-crust ore magmatic systems. 4. To model metal extraction, transportation and deposition at these `barriers' for systems of various `silicate melt - residual salt brines' ratios under the conditions of continental lithosphere. Comparison of real and modeled data allows us to conclude if a formation of a narrow zone of high metal concentration is possible at those critical levels (phase and geochemical `barriers'). The above-mentioned algorithm has been used for the Chineisky Pluton (the Transbaikal region, Siberia). Fortunately we have found our own `Merensky Reef', which happened to be a PGE enrichment marginal zone of the Chineisky Pluton due to specific fluid regime of crystallization! This work was supported by the Ministry for Russian Science and Education, Grant #DSP.2.1.1.702.

Impact, thermal, and shock sensitivity of molten TNT and of asphalt-contaminated molten TNT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mainiero, R.J.; Miron, Y.; Kwak, S.S.W.

1996-12-01

The research reported here was part of an effort to evaluate the safety of a process to recover TNT from MK-9 depth bombs by the autoclave meltout process. In this process the depth bombs are heated to 121 C so that the TNT will melt and run into a vat. Unfortunately, asphalt lining the inside surface of the bomb also melts and flows out with the TNT. Testing was conducted on molten TNT and molten TNT contaminated with 2 pct asphalt at 90, 100, 110, 120, 125, and 130 C. In the liquid drop test apparatus with a 2-kg weight,more » the molten TNT yielded a 50 pct probability of initiation at a drop height of 6.5 cm at 110 C, decreasing to 4.5 cm at 130 C. Asphalt-contaminated TNT was somewhat less impact-sensitive than pure TNT at temperatures of 110 to 125 C, but became more sensitive at 130 C. There is a 50 pct probability of initiation at a drop height of 7.8 cm at 110 C, decreasing to 3.3 cm at 130 C. In the card gap test, the molten TNT detonated at high velocity for a gap of 0.25 inches at 90 to 125 C and detonated at high velocity for a gap of 0.5 inches at 130 C. For gaps of 0.5 to 3 inches at 90 to 125 C and 0.75 inches to 3 inches at 130 C, the TNT did not detonate at high velocity but produced a violent explosion that caused significant damage to the test fixture. The thermal analysis test results showed that when asphalt is present in TNT, it greatly accelerates the exothermic decomposition of TNT, starting at temperatures near 200 C. It appears that at relatively low shock stimulus levels, the molten TNT may be undergoing a low velocity detonation, wherein the shock wave traveling through the gap test pipe cavitates the molten TNT, greatly increasing its sensitivity. These results are crucial for assuring continued safety in recovering TNT from munitions through the autoclave meltout process.« less

Use of a W-band polarimeter to measure microphysical characteristics of clouds

NASA Astrophysics Data System (ADS)

Galloway, John Charles

1997-08-01

This dissertation presents W-Band measurements of the copolar correlation co-efficient and Doppler spectrum taken from the University of Wyoming King Air research airplane. These measurements demonstrate the utility of making W-Band polarimetric and Doppler spectrum measurements from an airborne platform in investigations of cloud microphysical properties. Comparison of copolar correlation coefficient measurements with aircraft in situ probe measurements verifies that polarimetric measurements indicate phase transitions, and hydrometeor alignment in ice clouds. Melting layers in clouds were measured by the W-Band system on board the King Air during 1992 and 1994. Both measurements established the use of the linear depolarization ratio, LDR, to locate the melting layer using an airborne W-Band system. The measurement during 1994 allowed direct comparison of the magnitude of the copolar correlation coefficient with the values of LDR. The relation between the measurements corresponds with a predicted relationship between the two parameters for observation of particles exhibiting isotropy in the plane of polarization. Measurements of needle crystals at horizontal and vertical incidence provided further evidence that the copolar correlation coefficient values agreed with the expected response from hydrometeors possessing a preferred alignment for the side looking case, and hydrometeors without a preferred alignment for the vertical incidence case. Observation of significant specific differential phase at vertical incidence, the first reported at W-Band, corresponded to a significant increase in differential reflectivity overhead, which was most likely produced by hydrometeor alignment driven by cloud electrification. Comparison of the drop size distributions estimated using the Doppler spectra with those measured by the wingtip probes on the King Air reveals that the radar system is better suited under some liquid cloud conditions to provide microphysical measurements of the cloud or precipitation than the probes. The radiometric calibration of the radar system determines the accuracy of the drop size distribution estimate. The results presented here indicate that the procedure used to absolutely calibrate the W-Band radar system successfully characterized the reflectivity measurements to the extent required to obtain close correspondence between the radar and probe measurements of the drop size distribution.

Historical Analysis of Melt Pond Fraction on Arctic Sea Ice Through the Synthesis of High- and Medium- Resolution Optical Satellite Remote Sensing.

NASA Astrophysics Data System (ADS)

Wright, N.; Polashenski, C. M.

2017-12-01

Snow, ice, and melt ponds cover the surface of the Arctic Ocean in fractions that change throughout the seasons. These surfaces exert tremendous influence over the energy balance of the Arctic Ocean by controlling the absorption of solar radiation. Here we demonstrate the use of a newly released, open source, image classification algorithm designed to identify surface features in high resolution optical satellite imagery of sea ice. Through explicitly resolving individual features on the surface, the algorithm can determine the percentage of ice that is covered by melt ponds with a high degree of certainty. We then compare observations of melt pond fraction extracted from these images with an established method of estimating melt pond fraction from medium resolution satellite images (e.g. MODIS). Because high resolution satellite imagery does not provide the spatial footprint needed to examine the entire Arctic basin, we propose a method of synthesizing both high and medium resolution satellite imagery for an improved determination of melt pond fraction across whole Arctic. We assess the historical trends of melt pond fraction in the Arctic ocean, and address the question: Is pond coverage changing in response to changing ice conditions? Furthermore, we explore the image area that must be observed in order to get a locally representative sample (i.e. the aggregate scale), and show that it is possible to determine accurate estimates of melt pond fraction by observing sample areas significantly smaller than the typical footprint of high-resolution satellite imagery.

Thermodynamic properties of tungsten

NASA Astrophysics Data System (ADS)

Grimvall, Göran; Thiessen, Maria; Guillermet, Armando Fernández

1987-11-01

Tungsten has several unusual thermodynamic properties, e.g., very high values of the melting point, the entropy of fusion, the expansion on melting and the lattice anharmonicity. These features are given a semiquantitative explanation, based on the electron density of states N(E). Our treatment includes a numerical calculation of the electronic heat capacity from N(E) and a calculation of the entropy Debye temperature FTHETAS(T) from the vibrational part of the experimental heat capacity. FTHETAS(T) decreases by 36% from 300 K to the melting temperature 3695 K, the largest drop in FTHETAS for elemental metals. Recent quantum-mechanical ab initio calculations of the difference, Hβ/α, in Gibbs energy at T=0 K between the metastable fcc tungsten and the stable bcc phase yield Hβ/α=50+/-5 kJ/mol, which is much larger than the ``experimental'' values Hβ/α=10 and 19 kJ/mol derived from previous semiempirical analyses [the so-called calculation of phase diagrams (``CALPHAD'') method] of binary phase diagrams containing tungsten. We have reanalyzed CALPHAD data, using the results of the first part of this paper. Because of the shapes of N(E) of α-W and β-W, some usually acceptable CALPHAD procedures give misleading results. We give several estimates of Hβ/α, using different assumptions about the hypothetical melting temperature Tβf of fcc W. The more realistic of our estimates gives Hβ/α=30 kJ/mol or larger, thus reducing considerably the previous discrepancy between CALPHAD and ab initio results. The physical picture emerging from this work should be of importance in refinements of the CALPHAD method.

Highly Siderophile Elements and Osmium Isotope Systematics in Ureilites: Are the Carbonaceous Veins Primary Components?

NASA Technical Reports Server (NTRS)

Rankenburg, K.; Brandon, A. D.; Humayun, M.

2005-01-01

Ureilites are an enigmatic group of primitive carbon-bearing achondrites of ultramafic composition. The majority of the 143 ureilite meteorites consist primarily of olivine and pyroxene (and occasionally chromite) [1]. They are coarse-grained, slowly cooled, and depleted in incompatible lithophile elements. Minor amounts of dark interstitial material consisting of carbon, metal, sulfides, and fine-grained silicates occur primarily along silicate grain boundaries, but also intrude the silicates along fractures and cleavage planes. Variable degrees of impact shock features have also been imparted on ureilites. The prevailing two origins proposed for these rocks are either as melting residues of carbonaceous chondritic material [2], [3], or alternatively, derivation as mineral cumulates from such melts [4], [5], [6]. It has recently been proposed that ureilites are the residues of a smelting event, i.e. residues of a partial melting event under highly reducing conditions, where a solid Fe-bearing phase reacts with a melt and carbon to form Fe metal and carbon monoxide [7]. Rapid, localized extraction and loss of the basaltic component into space resulting from high eruption velocities could preserve unequilibrated oxygen isotopes and produce the observed olivine-pyroxene residues via 25-30% partial melting of chondritic-like precursor material.

Effect of SLP properties of vanadium SO/sub 2/ oxidation on reaction mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, K.C.; Nobile, A. Jr.

The SLP properties of a K/sub 2/SO/sub 4/-V/sub 2/O/sub 5/ catalysts during SO/sub 2/ oxidation and the intrinsic kinetics of the reaction on the SLPC were investigated and measured. The reason for the sudden drop in activation energy in the temperature range 440-470/sup 0/C is explained from the results of an investigation of the thermal and electrical behavior of the catalyst, and the distribution of active melt components. A reaction mechanism and rate equation consistent with the results are proposed and developed.

Unlocking the Secrets of the Mantle Wedge: New Insights Into Melt Generation Processes in Subduction Zones

NASA Astrophysics Data System (ADS)

Grove, T. L.

2007-05-01

Recent laboratory studies of the melting and crystallization behavior of mantle peridotite and subduction zone lavas have led to new insights into melting processes in island arc settings. Melting of the mantle wedge in the presence of H2O begins at much lower temperatures than previously thought. The solidus of mantle peridotite at 3 GPa is ~ 800 °C, which is 200 °C below previous estimates. At pressures greater than 2.4 GPa chlorite becomes a stable phase on the solidus and it remains stable until ~ 3.5 GPa. Therefore, melting over this pressure range occurs in the presence of chlorite, which contains ~ 12 wt. % H2O. Chlorite stabilized on the peridotite solidus by slab-derived H2O may be the ultimate source of H2O for subduction zone magmatism. Thus, chlorite could transport large amounts of H2O into the descending mantle wedge to depths where it can participate in melting to generate hydrous arc magmas. Our ability to identify primitive mantle melts at subduction zones has led to the following observations. 1) Primitive mantle melts show evidence of final equilibration at shallow depths near the mantle - crust boundary. 2) They contain variable amounts of dissolved H2O (up to 6 wt. %). 3) They record variable extents of melting (up to > 25 wt. %). To produce melts with such variable characteristics requires more than one melting process and requires consideration of a new type of melting called hydrous flux melting. Flux melting occurs when the H2O - rich melt initially produced on the solidus near the base of the mantle wedge ascends and continuously reacts with overlying hotter, shallower mantle. The mantle melts and magmatic H2O content is constantly diluted as the melt ascends and reacts with shallower, hotter mantle. Anhydrous mantle melts are also found in close temporal and spatial proximity to hydrous flux melts. These melts are extracted at similar depths near the top of the mantle wedge when mantle is advected up and into the wedge corner and melted by adiabatic decompression. In light of these new insights into the chemical processes that lead to melt generation in subduction zones, further study of the influence of mantle dynamics and physical processes on melting is crucial. Variations in mantle permeability near the base of the wedge may exercise important controls on the access of fluids and/or melts to the overlying wedge. The presence of chlorite in the wedge may also influence rheological properties and seismicity in the vicinity of the slab - wedge interface. Improved knowledge of rheology and permeability will help us to develop more robust models of mantle flow and temperature distribution in the mantle wedge. These are crucial for refining melting models. By combining evidence from petrology, geochemistry and geophysics the mysteries that attend the generation of melt in the mantle wedge can be resolved.

186Os-187Os and highly siderophile element abundance systematics of the mantle revealed by abyssal peridotites and Os-rich alloys

NASA Astrophysics Data System (ADS)

Day, James M. D.; Walker, Richard J.; Warren, Jessica M.

2017-03-01

Abyssal peridotites are oceanic mantle fragments that were recently processed through ridges and represent residues of both modern and ancient melting. To constrain the nature and timing of melt depletion processes, and the composition of the mantle, we report high-precision Os isotope data for abyssal peridotites from three ocean basins, as well as for Os-rich alloys, primarily from Mesozoic ophiolites. These data are complemented by whole-rock highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, Re), trace- and major-element abundances for the abyssal peridotites, which are from the Southwest Indian (SWIR), Central Indian (CIR), Mid-Atlantic (MAR) and Gakkel Ridges. The results reveal a limited role for melt refertilization or secondary alteration processes in modifying abyssal peridotite HSE compositions. The abyssal peridotites examined have experienced variable melt depletion (2% to >16%), which occurred >0.5 Ga ago for some samples. Abyssal peridotites typically exhibit low Pd/Ir and, combined with high-degrees of estimated total melt extraction, imply that they were relatively refractory residues prior to incorporation into their present ridge setting. Recent partial melting processes and mid-ocean ridge basalt (MORB) generation therefore played a limited role in the chemical evolution of their precursor mantle domains. The results confirm that many abyssal peridotites are not simple residues of recent MORB source melting, having a more complex and long-lived depletion history. Peridotites from the Gakkel Ridge, SWIR, CIR and MAR indicate that the depleted MORB mantle has 186Os/188Os of 0.1198356 ± 21 (2SD). The Phanerozoic Os-rich alloys yield an average 186Os/188Os within uncertainty of abyssal peridotites (0.1198361 ± 20). Melt depletion trends defined between Os isotopes and melt extraction indices (e.g., Al2O3) allow an estimate of the primitive mantle (PM) composition, using only abyssal peridotites. This yields 187Os/188Os (0.1292 ± 25), and 186Os/188Os of 0.1198388 ± 29, both of which are within uncertainty of previous primitive mantle estimates. The 186Os/188Os composition of the PM is less radiogenic than for some plume-related lavas, with the latter requiring sources with high long-term time-integrated Pt/Os. Estimates of primitive mantle HSE concentrations using abyssal peridotites define chondritic Pd/Ir, which differs from previous supra-chondritic estimates for Pd/Ir based on peridotites from a range of tectonic settings. By contrast, estimates of PM yield supra-chondritic Ru/Ir. The cause of enhanced Ru in the mantle remains enigmatic, but may reflect variable partitioning behavior of Ru at high pressure and temperature.

Origin of Aphyric Phonolitic Magmas: Natural Evidences and Experimental Constraints

NASA Astrophysics Data System (ADS)

Masotta, M.; Freda, C.; Gaeta, M.

2010-12-01

Large explosive phonolitic eruptions are commonly characterised by aphyric juvenile eruptive products. Taking into account the low density contrast among phonolitic composition and settling phases (i.e., feldspar and leucite), the almost complete lack of crystals in these differentiated compositions rises the question of which process could produce such an efficient crystal-melt separation. Seeking for an answer, we have investigated crystallization in presence of a thermal gradient as a possible mechanism for crystal-melt separation, considering both chemical and physical effects acting on a variably crystallized system. Using a natural tephri-phonolitic composition as starting material (M.te Aguzzo scoria cone, Sabatini Volcanic District, Central Italy), we have reproduced thermal gradient-driven crystallization in order to simulate the crystallization process in a thermally zoned magma chamber. Crystallization degree (paragenesis made of clinopyroxene±feldspars±leucite) as well as melt composition varies along the thermal gradient. In particular, melt composition ranges from the tephri-phonolitic starting composition at the bottom of the charge (hottest and aphyric zone) to phonolitic at the top (cooler and heterogeneously-crystallised zone). Backscattered images of experimental products clearly evidence: i) the aphyric tephri-phonolitic melt region at the bottom of the charge; ii) a drop-shaped crystal clustering in the middle zone; and iii) large aphyric belt and pockets (up to 100 µm wide) of phonolitic melt, with large deformed-shaped sanidine occurring at their margin, at the charge top region. The latter two features, resulting from solid-melt displacements, suggest that the segregation of phonolitic melt can be related to crystal sinking and compaction. On the other hand, the compositional variability of the melt along the thermal gradient is directly related to the crystallization degree, indicating that chemical diffusion and thermal migration have negligible effect at the experimental scale. Experimental results suggest that, in presence of a thermal gradient, a filter-press differentiation mechanism (i.e. sinking+compaction) is able to produce heterogeneous magma differentiation characterised by a wide range of melt compositions (in our case from tephri-phonolitic to phonolitic). Although the limitation due to the vertical shape of the charge and consequent shear effects occurring at the lateral walls (thus limiting the mobility of the crystal clusters), experimental duration of 24 h is enough to allow crystal-melt separation by means of settling and compaction, indicating that timescale for such a process is extremely rapid and effective at experimental conditions. Actually, experimental textures and phase relations are in good agreement with those observed in natural lithic enclaves (from Sabatini Volcanic District) representative of the crystallizing boundary layer of a phonolitic magma chamber. Thus, we speculate that gravitative collapses of a mushy zone from the magma chamber roof of a thermally zoned magma chamber may produce top accumulation of highly differentiated and aphyric melts.

High-throughput single-cell PCR using microfluidic emulsions

NASA Astrophysics Data System (ADS)

Guo, Mira; Mazutis, Linas; Agresti, Jeremy; Sommer, Morten; Dantas, Gautam; Church, George; Turnbaugh, Peter; Weitz, David

2012-02-01

The human gut and other environmental samples contain large populations of diverse bacteria that are poorly characterized and unculturable, yet have many functions relevant to human health. Our goal is to identify exactly which species carry some gene of interest, such as a carbohydrate metabolism gene. Conventional metagenomic assays sequence DNA extracted in bulk from populations of mixed cell types, and are therefore unable to associate a gene of interest with a species-identifying 16S gene, to determine that the two genes originated from the same cell. We solve this problem by microfluidically encapsulating single bacteria cells in drops, using PCR to amplify the two genes inside any drop whose encapsulated cell contains both genes, and sequencing the DNA from those drops that contain both amplification products.

Viscoelastic drops moving on hydrophilic and superhydrophobic surfaces.

PubMed

Xu, H; Clarke, A; Rothstein, J P; Poole, R J

2018-03-01

So-called "superhydrophobic" surfaces are strongly non-wetting such that fluid droplets very easily roll off when the surface is tilted. Our interest here is in understanding if this is also true, all else held equal, for viscoelastic fluid drops. We study the movement of Newtonian and well-characterised constant-viscosity elastic liquids when various surfaces, including hydrophilic (smooth glass), weakly hydrophobic (embossed polycarbonate) and superhydrophobic surfaces (embossed PTFE), are impulsively tilted. Digital imaging is used to record the motion and extract drop velocity. Optical and SEM imaging is used to probe the surfaces. In comparison with "equivalent" Newtonian fluids (same viscosity, density surface tension and contact angles), profound differences for the elastic fluids are only observed on the superhydrophobic surfaces: the elastic drops slide at a significantly reduced rate and complex branch-like patterns are left on the surface by the drop's wake including, on various scales, beads-on-a-string-like phenomena. The strong viscoelastic effect is caused by stretching filaments of fluid from isolated islands, residing at pinning sites on the surface pillars, of order ∼30 µm in size. On this scale, the local strain rates are sufficient to extend the polymer chains, locally increasing the extensional viscosity of the solution, retarding the drop. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Detection of environmental sources of Histoplasma capsulatum in Chiang Mai, Thailand, by nested PCR.

PubMed

Norkaew, Treepradab; Ohno, Hideaki; Sriburee, Pojana; Tanabe, Koichi; Tharavichitkul, Prasit; Takarn, Piyawan; Puengchan, Tanpalang; Bumrungsri, Sara; Miyazaki, Yoshitsugu

2013-12-01

Histoplasmosis is a systemic mycosis caused by inhaling spores of Histoplasma capsulatum, a dimorphic fungus. This fungus grows in soil contaminated with bat and avian excreta. Each year, patients with disseminated histoplasmosis have been diagnosed in Chiang Mai, northern Thailand. No published information is currently available on the environmental sources of this fungus in Chiang Mai or anywhere else in Thailand. The aim of this study was to detect H. capsulatum in soil samples contaminated with bat guano and avian droppings by nested PCR. Two hundred and sixty-five samples were collected from the following three sources: soil contaminated with bat guano, 88 samples; soil contaminated with bird droppings, 86 samples; and soil contaminated with chicken droppings, 91 samples. Genomic DNA was directly extracted from each sample, and H. capsulatum was detected by nested PCR using a primer set specific to a gene encoding 100-kDa-like protein (HcI, HcII and HcIII, HcIV). Histoplasma capsulatum was detected in seven of 88 soil samples contaminated with bat guano, one of 21 soil samples contaminated with pigeon droppings and 10 of 91 soil samples contaminated with chicken droppings. The results indicate the possibility of the association of bat guano and chicken droppings with H. capsulatum in this area of Thailand.

JSC Mars-1 Martian Soil Simulant: Melting Experiments and Electron Microprobe Studies

NASA Technical Reports Server (NTRS)

Carpenter, P.; Sebille, L.; Boles, W.; Chadwell, M.; Schwarz, L.

2003-01-01

JSC Mars-1 has been developed as a Martian regolith simulant, and is the <1 mm size fraction of a palagonitic tephra (a glassy volcanic ash altered at low temperatures) from Pu'u Nene cinder cone on the Island of Hawaii. The Mars-1 simulant forms the basis for numerous terrestrial studies which aim to evaluate the suitability of Martian soil for materials processing. Martian soil may be sintered to form building materials for construction, and also melted or reacted to extract metals for various uses, as well as oxygen for life support.

Modeling and control parameters for GMAW, short-circuiting transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cook, G.E.; DeLapp, D.R.; Barnett, R.J.

1996-12-31

Digital signal processing was used to analyze the electrical arc signals of the gas metal arc welding process with short-circuiting transfer. Among the features extracted were arc voltage and current (both average and peak values), short-circuiting frequency, arc period, shorting period, and the ratio of the arcing to shorting period. Additionally , a Joule heating model was derived which accurately predicted the melt-back distance during each short. The short-circuiting frequency, the ratio of the arc period to short periods, and the melt-back distance were found to be good indicators for monitoring and control of stable arc conditions.

Stir bar sorptive extraction of diclofenac from liquid formulations: a proof of concept study.

PubMed

Kole, Prashant Laxman; Millership, Jeff; McElnay, James C

2011-03-25

A new stir bar sorptive extraction (SBSE) technique coupled with HPLC-UV method for quantification of diclofenac in pharmaceutical formulations has been developed and validated as a proof of concept study. Commercially available polydimethylsiloxane stir bars (Twister™) were used for method development and SBSE extraction (pH, phase ratio, stirring speed, temperature, ionic strength and time) and liquid desorption (solvents, desorption method, stirring time etc) procedures were optimised. The method was validated as per ICH guidelines and was successfully applied for the estimation of diclofenac from three liquid formulations viz. Voltarol(®) Optha single dose eye drops, Voltarol(®) Ophtha multidose eye drops and Voltarol(®) ampoules. The developed method was found to be linear (r=0.9999) over 100-2000ng/ml concentration range with acceptable accuracy and precision (tested over three QC concentrations). The SBSE extraction recovery of the diclofenac was found to be 70% and the LOD and LOQ of the validated method were found to be 16.06 and 48.68ng/ml, respectively. Furthermore, a forced degradation study of a diclofenac formulation leading to the formation of structurally similar cyclic impurity (indolinone) was carried out. The developed extraction method showed comparable results to that of the reference method, i.e. method was capable of selectively extracting the indolinone and diclofenac from the liquid matrix. Data on inter and intra stir bar accuracy and precision further confirmed robustness of the method, supporting the multiple re-use of the stir bars. Copyright © 2010 Elsevier B.V. All rights reserved.

Operator care and eco-concerned development of a fast, facile and economical assay for basic nitrogenous drugs based on simplified ion-pair mini-scale extraction using safer solvent combined with drop-based spectrophotometry.

PubMed

Plianwong, Samarwadee; Sripattanaporn, Areerut; Waewsa-nga, Kwanrutai; Buacheen, Parin; Opanasopit, Praneet; Ngawhirunpat, Tanasait; Rojanarata, Theerasak

2012-08-30

A fast, facile, and economical assay for basic nitrogenous drugs has been developed based on the mini-scale extraction of the drug-dye ion pair complex combined with the use of safe-for-analyst and eco-friendlier organic extractant and drop-based micro-spectrophotometry. Instead of using large volume devices, the extraction was simply carried out in typical 1.5 mL microcentrifuge tubes along with the use of micropipettes for accurate transfer of liquids, vortex mixer for efficient partitioning of solutes and benchtop centrifuge for rapid phase separation. In the last step, back-extraction was performed by using the microvolume of acidic solution in order to concentrate the colored species into a confined aqueous microdrop and to keep the analyst away from unwanted contact and inhalation of organic solvents during the quantitation step which was achieved by using cuvetteless UV-vis micro-spectrophotometry without any prior dilutions. Using chlorpheniramine maleate as a representative analyte and n-butyl acetate as a less toxic and non-ozone depleting extractant, the miniaturized method was less laborious and much faster. It was accurate, precise and insensitive to the interferences from common excipients. Notably, it gave the assay results of drug in tablets and oral solution comparable to the large-scale pharmacopeial method while the consumption of organic solvents and the release of wastes were lowered by 200-400 folds. Copyright © 2012 Elsevier B.V. All rights reserved.

Hemolymph drop impact outcomes on surfaces with varying wettability

NASA Astrophysics Data System (ADS)

Milionis, Athanasios; Ghokulla Krishnan, K.; Loth, Eric

2015-08-01

Insect fouling from coagulated hemolymph and exoskeleton parts is a major challenge in the aerospace industry for the next generation of aerodynamic surfaces, which will employ laminar flow that requires extremely smooth surfaces. However, the wetting physics and dynamics of hemolymph (insect blood) on surfaces are not well understood. The present study seeks to gain a fundamental insight on the effect of surface wetting characteristics and dynamics resulting from a hemolymph drop impact, the first such study. In particular, hemolymph drops extracted from Acheta domesticus were dispensed from a range of heights to vary the kinetic impact on surfaces, which had widely varying water wetting behavior (from superhydrophilic to superhydrophobic). The impact dynamics were investigated with high-speed imaging while the dried residues were studied with optical microscopy. It was found that a superhydrophobic surface (based on thermoplastic with silica nano-particles) was able to significantly reduce hemolymph drop spreading, and even provide complete rebound when impacting on inclined surfaces.

Rapid detection of atrazine and metolachlor in farm soils: gas chromatography-mass spectrometry-based analysis using the bubble-in-drop single drop microextraction enrichment method.

PubMed

Williams, D Bradley G; George, Mosotho J; Marjanovic, Ljiljana

2014-08-06

Tracking of metolachlor and atrazine herbicides in agricultural soils, from spraying through to harvest, was conducted using our recently reported "bubble-in-drop single-drop microextraction" method. The method showed good linearity (R(2) = 0.999 and 0.999) in the concentration range of 0.01-1.0 ng/mL with LOD values of 0.01 and 0.02 ng/mL for atrazine and metolachlor, respectively. Sonication methods were poor at releasing these herbicides from the soil matrixes, while hot water extraction readily liberated them, providing an efficient accessible alternative to sonication techniques. Good recoveries of 97% and 105% were shown for atrazine and metolachlor, respectively, from the soil. The spiking protocol was also investigated, resulting in a traceless spiking method. We demonstrate a very sensitive technique by which to assess, for example, the length of residence of pesticides in given soils and thus risk of exposure.

Split rheometer Couette attachment to enable sample extraction

NASA Astrophysics Data System (ADS)

Guthrie, Sarah E.; Idziak, Stefan H. J.

2005-02-01

We report on the development of a Couette attachment insert for a rheometer, which is designed to split in half, enabling intact sample extraction of cocoa butter crystallized from the melt under known dynamic stress conditions. This cell is capable of producing a sample 1mm thick. At shear rates of 90-720s-1 and final temperatures of 18-20°C it was shown that the sample will completely separate from the cell surface intact.

Temperature and Time Constraints on Dissolution, Fe-Mg Exchange and Zoning between Relict Forsterite and Chondrule Melt - Implications for Thermal History of Chondrules

NASA Astrophysics Data System (ADS)

Ustunisik, G. K.; Ebel, D. S. S.; Walker, D.

2016-12-01

The chemical and textural characteristics of different generations of relict olivine grains in chondrules record the fact that chondrules were re-melted. Mineral dissolution, Fe-Mg exchange, and zoning within the relict crystals constrain the T-t aspects of this re-melting process. Here, we performed isothermal and dynamic cooling experiments at LDEO of Columbia University. For each run, a cubic crystal of known dimensions of Mogok forsterite (Fo99) was placed in synthetic Type IIA chondrule mesostasis with 4.92 wt% FeO (TLiq 1315ºC). Pressed pellets of this mixture were hung on Pt-wire loops and inserted in vertical Deltech furnace where CO-CO2 gas mixtures kept fO2 IW-1. For isothermal experiments, each charge was heated to 1428ºC, 1350ºC, 1250ºC, and 1150ºC and was held there from 20 mins to several days (>3 days) before drop-quenching into cold water. The dynamic crystallization experiments were held at 1428ºC for 20 mins, cooled at rates of 75ºC, 722ºC, and 1444ºC/hr to 1000ºC and then water quenched. X-ray-CT and EMPA at AMNH were used to image the partially resorbed/zoned olivines in 3-D before and after each run to observe textural evolution of the crystal shapes and volumes and to determine chemical changes. The isothermal experiments at 1150 and 1250ºC for 20 mins, produced no bulk FeO diffusion into the Mogok forsterite. Very minor Fe-Mg exchange at the crystal rims gives slight MgO zoning within the nearby melt. With increasing duration (1 hr and 22 hrs), at 1250ºC, embayments of melt form into the rims of the crystal (amplified at 22 hrs) with significant Fe-Mg exchange. FeO content of Mogok increased with major MgO zonation within nearby melt. At 1150ºC, the same increase in FeO in Mogok and zonation in nearby glass could only be achieved in >3 days experiment. At high Ts (1428ºC) in 20 min run, 75 volume % of Mogok forsterite has been dissolved into the melt. Resorption erodes the Fe-Mg exchange at the rims of the crystal. At longer duration experiments (1250ºC, 22 hrs and 1150ºC, >3days) quench olivine crystals and silica (cristobalite) have been observed within the melt along with low-Ca pyroxene along the edges of the Mogok forsterite. The metastable pyroxene acts as a protective cover thwarting Fe-Mg exchange between Mogok and Fe-bearing melt. The cristobalite occurred as a result of melt fractionation.

Mineral chemistry and geochemistry of ophiolitic metaultramafics from Um Halham and Fawakhir, Central Eastern Desert, Egypt

NASA Astrophysics Data System (ADS)

Abdel-Karim, Abdel-Aal M.; Ali, Shehata; El-Shafei, Shaimaa A.

2018-03-01

This study is focused on ophiolitic metaultramafics from Um Halham and Fawakhir, Central Eastern Desert of Egypt. The rocks include serpentinized peridotites, serpentinites together with talc- and quartz-carbonates. The primary spinel relict is Al-chromite [Cr# > 60], which is replaced by Cr-magnetite during metamorphism. The high Cr# of Al-chromites resembles supra-subduction zone (SSZ) peridotites and suggests derivation from the deeper portion of the mantle section with boninitic affinity. These mantle rocks equilibrated with boninitic melt have been generated by high melting degrees. The estimated melting degrees ( 19-24%) lie within the range of SSZ peridotites. The high Cr# of spinel and Fo content of olivine together with the narrow compositional range suggest a mantle residual origin. Serpentinized peridotite and serpentinites have low Al2O3/SiO2 ratios (mostly < 0.03) like fore-arc mantle wedge serpentinites and further indicate that their mantle protolith had experienced partial melting before serpentinization process. Moreover, they have very low Nb, Ta, Zr and Hf concentrations along with sub-chondritic Nb/Ta (0.3-16) and Zr/Hf (mostly 1-20) ratios further confirming that their mantle source was depleted by earlier melting extraction event. The high chondrite normalized (La/Sm)N ratios (average 10) reflect input of subduction-related slab melts/fluids into their mantle source.

What Petit-Spot Volcanoes Tell us about the Lithosphere-Asthenosphere Boundary?

NASA Astrophysics Data System (ADS)

Pilet, S.; Abe, N.; Rochat, L.; Kaczmarek, M. A.; Bessat, A.; Duretz, T.; Muntener, O.

2015-12-01

The top of the low seismic velocity zone (LVZ) is frequently used to localize the lithosphere -asthenosphere boundary (LAB) which separates rigid oceanic plates from the underlying ductile asthenosphere. The seismic and electric properties of the LVZ are generally explained by the presence of low degree melts located at the base of the lithosphere, but the composition of these melts (silicate or carbonated melts) is still in debate. If most models for the LAB are based on geophysical or experimental studies, the discovery of petit-spot volcanoes on the top of the down-going Pacific plate (1) provides unique opportunities to obtain direct information on the LAB. Petit-spot volcanoes are interpreted as small-scale seamounts formed by the extraction of low-degree melts from the base of the lithosphere in response of plate flexure and/or crack propagation (2). The petrology of petit-spot lavas from Japan and Costa Rica demonstrates, first, that melts from the LVZ correspond to volatiles rich low degree silicate melts rather then to carbonatitic melts. Second, the discovery of lithospheric metasomatized mantle xenoliths and xenocrysts in the petit-spot lavas suggest that plate bending in front of subduction zones does not only produce petit-spot lavas at the surface, but allowed low degree melts from the LVZ to percolate and differentiate across the base of the oceanic lithosphere. This observation has important implication for the LAB because it demonstrates that deformed LAB does not represent a impermeable barrier for melt percolation as communally assumed, but deformation allows melts from the asthenosphere to percolate through peridotite matrix for significant distance (~10-20 km) modifying the rheology and the seismic properties of the base of the lithospheric mantle. This aspect needs to be taking into account in any model trying to simulate lithosphere asthenosphere deformation. (1) Hirano et al., 2006, Science 313, 1426-1428; (2) Valentine & Hirano, 2010, Geology 38, 55-58.

Magmatism in Lithosphere Delamination process inferred from numerical models

NASA Astrophysics Data System (ADS)

Göǧüş, Oǧuz H.; Ueda, Kosuke; Gerya, Taras

2017-04-01

The peel away of the oceanic/continental slab from the overlying orogenic crust has been suggested as a ubiquitous process in the Alpine-Mediterranean orogenic region (e.g. Carpathians, Apennines, Betics and Anatolia). The process is defined as lithospheric delamination where a slab removal/peel back may allow for the gradual uprising of sub-lithospheric mantle, resulting in high heat flow, transient surface uplift/subsidence and varying types of magma production. Geodynamical modeling studies have adressed the surface response to the delamination in the context of regional tectonic processes and explored wide range of controlling parameters in pre-syn and post collisional stages. However, the amount and styles of melt production in the mantle (e.g. decompression melting, wet melting in the wedge) and the resulting magmatism due to the lithosphere delamination remains uncertain. In this work, by using thermomechanical numerical experiments, designed in the configuration of subduction to collision, we investigated how melting in the mantle develops in the course of delamination. Furthermore, model results are used to decipher the distribution of volumetric melt production, melt extraction and the source of melt and the style of magmatism (e.g. igneous vs. volcanic). The model results suggest that a broad region of decompression melting occurs under the crust, mixing with the melting of the hydrated mantle derived by the delaminating/subducting slab. Depending on the age of the ocean slab, plate convergence velocity and the mantle temperature, the melt production and crust magmatism may concentrate under the mantle wedge or in the far side of the delamination front (where the subduction begins). The slab break-off usually occurs in the terminal stages of the delamination process and it may effectively control the location of the magmatism in the crust. The model results are reconciled with the temporal and spatial distribution of orogenic vs. anorogenic magmatism in the Mediterranean region in which the latter may have developed due to the delamination process.

Microstructural evidence of melting in crustal rocks (Invited)

NASA Astrophysics Data System (ADS)

Holness, M. B.; Cesare, B.; Sawyer, E. W.

2010-12-01

The signature of the former presence of melt on a microscopic scale is highly variable, subject to modification both during the melting event and during its subsequent history. Static pyrometamorphism results in melt films on grain boundaries between reactant phases. If a volume increase is involved, melting results in hydrofracture. On a longer timescale, as demonstrated by fragments of the crustal source in lava flows at El Hoyazo (SE Spain), melt occurs throughout the rock. These examples are highly unusual: the great majority of rocks that underwent melting cooled more slowly, permitting microstructural modification driven by a combination of textural equilibration, reaction and deformation. In the absence of deformation, and at constant temperature, melt-bearing rocks approach textural equilibrium, characterised by uniform grain size, smoothly curved grain boundaries and the establishment at all three-grain junctions of the equilibrium dihedral angle. The dihedral angle controls melt connectivity, with consequences for melt mobility and rock rheology. However, deformation is the rule rather than the exception in regional metamorphic terrains with profound effects on melt distribution. If deformation occurs predominantly by diffusive processes, textural equilibration can keep pace. At higher deformation rates melt is squeezed into planar pockets aligned parallel to the shearing direction or perpendicular to the extensional stress. Microstructures formed during solidification are controlled by cooling rate, H2O, and the size of the melt pockets. Large pockets solidify to look like igneous rocks. In small pores the supersaturation required for crystal growth is high and melt persist to lower temperatures, even being preserved as tiny glassy inclusions (“nanogranites”) in regional terranes. The pore size effect changes crystallization order, resulting in small, highly cuspate grains on grain boundaries with low dihedral angles. Crystallisation microstructures of poly-component liquids are highly dependent on diffusion rates, and therefore H2O content. Dry conditions result in diffusion-limited crystallisation to form intergrowths and symplectites (e.g. granophyre). The cooling rate must be slow in order to nucleate and grow individual grains from the melt. If the melt was primarily concentrated in thick films on grain boundaries this results in the “string of beads” texture. If there is sufficient water, and the rocks stay sufficiently hot, the microstructures will move towards a granular texture, driven by the reduction in interfacial energy. Highly cuspate pseudomorphs of melt at three-grain junctions will become rounded as the dihedral angle increases (generally towards the range 110-140°). Melt-related microstructures are more likely to be retained in dry rocks: in migmatite terranes in which melting was driven by infiltration of aqueous fluids and where melt extraction wasn’t pervasive, microstructures are likely to have been significantly modified by sub-solidus recrystallisation, especially likely if the rock underwent intense deformation on the retrograde path.

Simultaneous extraction and determination of albendazole and triclabendazole by a novel syringe to syringe dispersive liquid phase microextraction-solidified floating organic drop combined with high performance liquid chromatography.

PubMed

Asadi, Mohammad; Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad

2016-08-17

A syringe to syringe dispersive liquid phase microextraction-solidified floating organic drop was introduced and used for the simultaneous extraction of trace amounts of albendazole and triclabendazole from different matrices. The extracted analytes were determined by high performance liquid chromatography along with fluorescence detection. The analytical parameters affecting the microextraction efficiency including the nature and volume of the extraction solvent, sample volume, sample pH, ionic strength and the cycles of extraction were optimized. The calibration curves were linear in the range of 0.1-30.0 μg L(-1) and 0.2-30.0 μg L(-1) with determination coefficients of 0.9999 and 0.9998 for albendazole and triclabendazole respectively. The detection limits defined as three folds of the signal to noise ratio were found to be 0.02 μg L(-1) for albendazole and 0.06 μg L(-1) for triclabendazole. The inter-day and intra-day precision (RSD%) for both analytes at three concentration levels (0.5, 2.0 and 10.0 μg L(-1)) were in the range of 6.3-10.1% and 5.0-7.5% respectively. The developed method was successfully applied to determine albendazole and triclabendazole in water, cow milk, honey, and urine samples. Copyright © 2016. Published by Elsevier B.V.

Antimicrobial and Herbal Drug Resistance in Enteric Bacteria Isolated from Faecal Droppings of Common House Lizard/Gecko (Hemidactylus frenatus).

PubMed

Singh, Bhoj R; Singh, Vidya; Ebibeni, N; Singh, Raj K

2013-01-01

From 194 faecal dropping samples of common house geckos collected from offices (60), houses (88), integrated farm units (IFS,18) and hostels, guest houses, and dining rooms of different canteen/mess (HGM, 28), 326 bacterial isolates of enteric bacteria belonging to 17 genera and 34 species were detected. Escherichia coli were the most frequently (39) isolated followed by Citrobacter freundii (33), Klebsiella pneumonia (27), Salmonella indica (12), Enterobacter gergoviae (12), and Ent. agglomerans (11). Other important bacteria isolated from gecko droppings were Listonella damsela (2), Raoultella terrigena (3), S. salamae (2), S. houtenae (3), Edwardsiella tarda (4), Edwardsiella hoshinae (1), and Klebsiella oxytoca (2). Of the 223 isolates tested for antimicrobial drug sensitivity, 27 (12.1%) had multiple drug resistance (MDR). None of the salmonellae or edwardsiellae had MDR however, MDR strains were significantly more common among Escherichia spp. (P = 1.9 × 10(-5)) and isolates from IFS units (P = 3.58 × 10(-23)). The most effective herbal drug, Ageratum conyzoides extract, inhibited growth of only 27.8% of strains tested followed by ethanolic extract of Zanthoxylum rhetsa (13.9%), eucalyptus oil (5.4%), patchouli oil (5.4%), lemongrass oil (3.6%), and sandalwood oil (3.1%), and Artemisia vulgaris essential oil (3.1%).

Drop-to-drop solvent microextraction coupled with gas chromatography/mass spectrometry for rapid determination of trimeprazine in urine and blood of rats: application to pharmacokinetic studies.

PubMed

Agrawal, Kavita; Wu, Hui-Fen

2007-01-01

A simple and rapid method based on drop-to-drop solvent microextraction (DDSME) coupled with gas chromatography/mass spectrometry (GC/MS) has been successfully applied for the pharmacokinetic studies of trimeprazine in 8 microL of urine and blood samples of rats. Several factors that influenced the extraction efficiency of DDSME, such as selection of organic solvent, extraction time, exposure volume of organic phase, addition of salt and pH, were optimized. Linearity was obtained over the concentration ranges of 0.2-10, 0.25-7.0 and 0.5-6.0 microg/mL with correlation coefficients of 0.998, 0.996 and 0.993 in deionized water, urine and blood samples of rats, respectively. The limits of detection (LODs) of trimeprazine were 0.05, 0.06 and 0.1 microg/mL in deionized water, urine and blood samples. The concentrations of trimeprazine obtained in urine and blood samples of rats were 0.21-1.25 and 2.72-0.22 microg/mL, respectively, after a single intravenous administration of this drug. The enrichment factors and LOD values obtained by DDSME coupled to GC/MS were compared with those of hollow fiber liquid-phase microextraction (HF-LPME) combined with GC/MS. We believe that this novel approach can be very useful in clinical application since only one microdrop of biological samples was required to perform the pharmacokinetic studies from rats, so the sample pretreatments for animal experiments can be very easy too. Copyright (c) 2007 John Wiley & Sons, Ltd.

Silica-enriched mantle sources of subalkaline picrite-boninite-andesite island arc magmas

NASA Astrophysics Data System (ADS)

Bénard, A.; Arculus, R. J.; Nebel, O.; Ionov, D. A.; McAlpine, S. R. B.

2017-02-01

Primary arc melts may form through fluxed or adiabatic decompression melting in the mantle wedge, or via a combination of both processes. Major limitations to our understanding of the formation of primary arc melts stem from the fact that most arc lavas are aggregated blends of individual magma batches, further modified by differentiation processes in the sub-arc mantle lithosphere and overlying crust. Primary melt generation is thus masked by these types of second-stage processes. Magma-hosted peridotites sampled as xenoliths in subduction zone magmas are possible remnants of sub-arc mantle and magma generation processes, but are rarely sampled in active arcs. Published studies have emphasised the predominantly harzburgitic lithologies with particularly high modal orthopyroxene in these xenoliths; the former characteristic reflects the refractory nature of these materials consequent to extensive melt depletion of a lherzolitic protolith whereas the latter feature requires additional explanation. Here we present major and minor element data for pristine, mantle-derived, lava-hosted spinel-bearing harzburgite and dunite xenoliths and associated primitive melts from the active Kamchatka and Bismarck arcs. We show that these peridotite suites, and other mantle xenoliths sampled in circum-Pacific arcs, are a distinctive peridotite type not found in other tectonic settings, and are melting residues from hydrous melting of silica-enriched mantle sources. We explore the ability of experimental studies allied with mantle melting parameterisations (pMELTS, Petrolog3) to reproduce the compositions of these arc peridotites, and present a protolith ('hybrid mantle wedge') composition that satisfies the available constraints. The composition of peridotite xenoliths recovered from erupted arc magmas plausibly requires their formation initially via interaction of slab-derived components with refractory mantle prior to or during the formation of primary arc melts. The liquid compositions extracted from these hybrid sources are higher in normative quartz and hypersthene (i.e., they have a more silica-saturated character) in comparison with basalts derived from prior melt-depleted asthenospheric mantle beneath ridges. These primary arc melts range from silica-rich picrite to boninite and high-Mg basaltic andesite along a residual spinel harzburgite cotectic. Silica enrichment in the mantle sources of arc-related, subalkaline picrite-boninite-andesite suites coupled with the amount of water and depth of melting, are important for the formation of medium-Fe ('calc-alkaline') andesite-dacite-rhyolite suites, key lithologies forming the continental crust.

Parametric effects on pinch-off modes in liquid/liquid jet systems

NASA Astrophysics Data System (ADS)

Milosevic, Ilija N.

Many industries rely on liquid/liquid extraction systems, where jet pinch off occurs on a regular basis. Inherent short time and length scales make analytical and numerical simulation of the process very challenging. A main objective of this work was to document the details of various pinch-off modes at different length scales using Laser Induced Fluorescence and Particle Image Velocimetry. A water glycerine mixture was injected into ambient either silicone oil or 1-octanol. The resultant viscosity ratios, inner to outer fluid, were 1.6 and 2.8, respectively. Ohnesorge numbers were 0.013 for ambient silicone oil and 0.08 for ambient 1-octanol. Reynolds and Strouhal numbers ranged from 30 to 100 and 0.5 to 3.5, respectively. Decreasing the Strouhal number increased the number of drops formed per forcing. Increasing the Reynolds number suppressed satellite formation, and in some cases the number of drops decreased from two to one per cycle. Increasing the Ohnesorge number to 0.08 suppressed the pinch off yielding a longer jet with three-dimensional threads. At Ohnesorge number 0.013, increasing the forcing amplitude shortened the jet, and eventually led to a dripping mode. High-resolution measurements of pinch-off angles were compared to results from similarity theory. Two modes were investigated: drops breaking from the jet (jet/drop) and, one drop splitting into two (splitting drop). The jet/drop mode angle measurements agreed with similarity predictions. The splitting drop mode converged towards smaller angles. Scaling analysis showed that a Stokesian similarity regime applied for a neck radius of 6 microns or less. The smallest radius observed in experiments was 15 microns. Therefore, it is not known whether splitting drop mode might still converge to same behavior.

Clinopyroxene dissolution in basaltic melt

NASA Astrophysics Data System (ADS)

Chen, Yang; Zhang, Youxue

2009-10-01

The history of magmatic systems may be inferred from reactions between mantle xenoliths and host basalt if the thermodynamics and kinetics of the reactions are quantified. To study diffusive and convective clinopyroxene dissolution in silicate melts, diffusive clinopyroxene dissolution experiments were conducted at 0.47-1.90 GPa and 1509-1790 K in a piston-cylinder apparatus. Clinopyroxene saturation is found to be roughly determined by MgO and CaO content. The effective binary diffusivities, DMgO and DCaO, and the interface melt saturation condition, C0MgO×C0CaO, are extracted from the experiments. DMgO and DCaO show Arrhenian dependence on temperature. The pressure dependence is small and not resolved within 0.47-1.90 GPa. C0MgO×C0CaO in the interface melt increases with increasing temperature, but decreases with increasing pressure. Convective clinopyroxene dissolution, where the convection is driven by the density difference between the crystal and melt, is modeled using the diffusivities and interface melt saturation condition. Previous studies showed that the convective dissolution rate depends on the thermodynamics, kinetics and fluid dynamics of the system. Comparing our results for clinopyroxene dissolution to results from a previous study on convective olivine dissolution shows that the kinetic and fluid dynamic aspects of the two minerals are quite similar. However, the thermodynamics of clinopyroxene dissolution depends more strongly on the degree of superheating and composition of the host melt than that of olivine dissolution. The models for clinopyroxene and olivine dissolution are tested against literature experiments on mineral-melt interaction. They are then applied to previously proposed reactions between Hawaii basalts and mantle minerals, mid-ocean ridge basalts and mantle minerals, and xenoliths digestion in a basalt at Kuandian, Northeast China.

Meltwater Contributions to Irrigation in High Mountain Asia Under a Changing Climate

NASA Astrophysics Data System (ADS)

Grogan, D. S.; Wisser, D.; Proussevitch, A. A.; Lammers, R. B.; Frolking, S. E.

2016-12-01

Snow melt and glacier melt are known to contribute significantly to river flows in High Mountain Asia. This region is also an important agricultural producer, and relies heavily on irrigation. In this study we use a hydrologic model coupled with a glacier model to quantify the historical contribution of snow melt and glacier melt to irrigation water use in High Mountain Asia, with detailed basin-level budgets of meltwater use, re-use, and contributions to crop evapotranspiration. We find that it is important to quantify not only how much meltwater is extracted from rivers and reservoirs for irrigation, but also to track this water through irrigation return flows and downstream re-use. We also project future basin-level meltwater use for irrigation, making use of a suite of climate model projections and associated glacier model projections. We assess the relative importance of snow melt and glacier melt to irrigation supplies across seasons, and for future projections we compare temporal shifts in meltwater hydrographs to potential shifts in crop planting dates due to increasing temperatures and shifts in monsoon onset. Results show that, historically (c. 2000), meltwater for irrigation is most important in the Indus and Ganges basins, which use 90 km3yr-1 and 20 km3yr-1 meltwater, respectively. In both basins, snow melt contributions to annual irrigation use are larger than glacier melt contributions, but the relative importance of these two meltwater sources shifts through the growing season. Uncertainties in future precipitation projections lead to large differences in the direction of change of future meltwater use for irrigation: depending upon the climate model and pathway used, we find that meltwater availability may decrease or increase in 2070-2099 compared to historical results.

Response surface methodology based on central composite design as a chemometric tool for optimization of dispersive-solidification liquid-liquid microextraction for speciation of inorganic arsenic in environmental water samples.

PubMed

Asadollahzadeh, Mehdi; Tavakoli, Hamed; Torab-Mostaedi, Meisam; Hosseini, Ghaffar; Hemmati, Alireza

2014-06-01

Dispersive-solidification liquid-liquid microextraction (DSLLME) coupled with electrothermal atomic absorption spectrometry (ETAAS) was developed for preconcentration and determination of inorganic arsenic (III, V) in water samples. At pH=1, As(III) formed complex with ammonium pyrrolidine dithiocarbamate (APDC) and extracted into the fine droplets of 1-dodecanol (extraction solvent) which were dispersed with ethanol (disperser solvent) into the water sample solution. After extraction, the organic phase was separated by centrifugation, and was solidified by transferring into an ice bath. The solidified solvent was transferred to a conical vial and melted quickly at room temperature. As(III) was determined in the melted organic phase while As(V) remained in the aqueous layer. Total inorganic As was determined after the reduction of the pentavalent forms of arsenic with sodium thiosulphate and potassium iodide. As(V) was calculated by difference between the concentration of total inorganic As and As(III). The variable of interest in the DSLLME method, such as the volume of extraction solvent and disperser solvent, pH, concentration of APDC (chelating agent), extraction time and salt effect, was optimized with the aid of chemometric approaches. First, in screening experiments, fractional factorial design (FFD) was used for selecting the variables which significantly affected the extraction procedure. Afterwards, the significant variables were optimized using response surface methodology (RSM) based on central composite design (CCD). In the optimum conditions, the proposed method has been successfully applied to the determination of inorganic arsenic in different environmental water samples and certified reference material (NIST RSM 1643e). Copyright © 2014 Elsevier B.V. All rights reserved.

Transport of metals and sulphur in magmas by flotation of sulphide melt on vapour bubbles

NASA Astrophysics Data System (ADS)

Mungall, J. E.; Brenan, J. M.; Godel, B.; Barnes, S. J.; Gaillard, F.

2015-03-01

Emissions of sulphur and metals from magmas in Earth’s shallow crust can have global impacts on human society. Sulphur-bearing gases emitted into the atmosphere during volcanic eruptions affect climate, and metals and sulphur can accumulate in the crust above a magma reservoir to form giant copper and gold ore deposits, as well as massive sulphur anomalies. The volumes of sulphur and metals that accumulate in the crust over time exceed the amounts that could have been derived from an isolated magma reservoir. They are instead thought to come from injections of multiple new batches of vapour- and sulphide-saturated magmas into the existing reservoirs. However, the mechanism for the selective upward transfer of sulphur and metals is poorly understood because their main carrier phase, sulphide melt, is dense and is assumed to settle to the bottoms of magma reservoirs. Here we use laboratory experiments as well as gas-speciation and mass-balance models to show that droplets of sulphide melt can attach to vapour bubbles to form compound drops that float. We demonstrate the feasibility of this mechanism for the upward mobility of sulphide liquids to the shallow crust. Our work provides a mechanism for the atmospheric release of large amounts of sulphur, and contradicts the widely held assumption that dense sulphide liquids rich in sulphur, copper and gold will remain sequestered in the deep crust.

High-Temperature Wettability and Interactions between Y-Containing Ni-Based Alloys and Various Oxide Ceramics.

PubMed

Li, Jinpeng; Zhang, Huarui; Gao, Ming; Li, Qingling; Bian, Weidong; Tao, Tongxiang; Zhang, Hu

2018-05-07

To obtain appropriate crucible materials for vacuum induction melting of MCrAlY alloys, four different oxide ceramics, including MgO, Y₂O₃, Al₂O₃, and ZrO₂, with various microstructures were designed and characterized. The high-temperature wettability and interactions between Ni-20Co-20Cr-10Al-1.5Y alloys and oxide ceramics were studied by sessile drop experiments under vacuum. The results showed that all the systems exhibited non-wetting behavior. The contact angles were stable during the melting process of alloys and the equilibrium contact angles were 140° (MgO), 148° (Y₂O₃), 154° (Al₂O₃), and 157° (ZrO₂), respectively. The interfacial reaction between the ceramic substrates and alloys occurred at high temperature. Though the ceramics had different microstructures, similar continuous Y₂O₃ reaction layer with thicknesses of about 25 μm at the alloy-ceramic interface in MgO, Al₂O₃, and ZrO₂ systems formed. The average area percentage of oxides in the alloy matrices were 0.59% (MgO), 0.11% (Al₂O₃), 0.09% (ZrO₂), and 0.02% (Y₂O₃), respectively. The alloys, after reacting with MgO ceramic, had the highest inclusion content, while those with the lowest content were in the Y₂O₃ system. Y₂O₃ ceramic was the most beneficial for vacuum induction melting of high-purity Y-containing Ni-based alloys.

A Computational Approach to Modeling Magma Ocean Evolution in 2-D and 3-D

NASA Astrophysics Data System (ADS)

Tackley, P. J.; Louro Lourenço, D. J.; Fomin, I.

2017-12-01

Models of magma ocean evolution have typically been performed in 1-D (e.g. Abe, PEPI 1997; Solomatov and Stevenson, JGR 1993; Elkins-Tanton EPSL 2008). However, 1-D models may miss important aspects of the process, in particular the possible development of solid-state convection before the magma ocean has completely crystallised, and possible large-scale overturn driven by thermal and/or compositional gradients. On the other hand, fully resolving magma ocean evolution in 2-D or 3-D would be extremely challenging due to the small time-scales and length-scales associated with turbulent convection in the magma and the extreme viscosity contrast between regions of high melt fraction and regions of low melt fraction, which are separated by a rheological threshold associated with the solid forming an interconnected matrix. Here, an intermediate approach to treat these has been implemented within the framework of the mantle convection code StagYY (Tackley, PEPI 2008). The basic approach is to resolve processes that occur in the mostly solid state (i.e. below the rheological threshold) while parameterising processes that occur in the mostly liquid state, based largely on the works of Y. Abe. Thus, turbulent convection in magma-rich regions is treated using an effective thermal conductivity based on mixing-length theory, and segregation of solid and liquid is treated using Darcy's law for low melt fractions or crystal settling (offset by vigorous convection) for high melt fractions. At the outer surface a combined radiative-conductive heat balance is implemented, including the temperature drop over a very thin ( cm) thermal boundary layer and reduction of radiative heat loss by an atmosphere. Key to the whole process is petrology: the coexisting compositions of magma and solid under various conditions including possible fractionation, and for this different approaches have been parameterised ranging from a simple basalt-harzburgite parameterisation to a bi-eutectic lower mantle melting model based on ab initio and laboratory experiments.

A computational approach to modelling magma ocean evolution in 2-D and 3-D

NASA Astrophysics Data System (ADS)

Tackley, Paul; Lourenco, Diogo; Fomin, Ilya

2017-04-01

Models of magma ocean evolution have typically been performed in 1-D (e.g. Abe, PEPI 1997; Solomatov and Stevenson, JGR 1993; Elkins-Tanton EPSL 2008). However, 1-D models may miss important aspects of the process, in particular the possible development of solid-state convection before the magma ocean has completely crystallised, and possible large-scale overturn driven by thermal and/or compositional gradients. On the other hand, fully resolving magma ocean evolution in 2-D or 3-D would be extremely challenging due to the small time-scales and length-scales associated with turbulent convection in the magma and the extreme viscosity contrast between regions of high melt fraction and regions of low melt fraction, which are separated by a rheological threshold associated with the solid forming an interconnected matrix. Here, an intermediate approach to treat these has been implemented within the framework of the mantle convection code StagYY (Tackley, PEPI 2008). The basic approach is to resolve processes that occur in the mostly solid state (i.e. below the rheological threshold) while parameterising processes that occur in the mostly liquid state, based largely on the works of Y. Abe. Thus, turbulent convection in magma-rich regions is treated using an effective thermal conductivity based on mixing-length theory, and segregation of solid and liquid is treated using Darcy's law for low melt fractions or crystal settling (offset by vigorous convection) for high melt fractions. At the outer surface a combined radiative-conductive heat balance is implemented, including the temperature drop over a very thin ( cm) thermal boundary layer and reduction of radiative heat loss by an atmosphere. Key to the whole process is petrology: the coexisting compositions of magma and solid under various conditions including possible fractionation, and for this different approaches have been parameterised ranging from a simple basalt-harzburgite parameterisation to a bi-eutectic lower mantle melting model based on ab initio and laboratory experiments.

Characterization and reproducibility of HepG2 hanging drop spheroids toxicology in vitro.

PubMed

Hurrell, Tracey; Ellero, Andrea Antonio; Masso, Zelie Flavienne; Cromarty, Allan Duncan

2018-02-21

Hepatotoxicity remains a major challenge in drug development despite preclinical toxicity screening using hepatocytes of human origin. To overcome some limitations of reproducing the hepatic phenotype, more structurally and functionally authentic cultures in vitro can be introduced by growing cells in 3D spheroid cultures. Characterisation and reproducibility of HepG2 spheroid cultures using a high-throughput hanging drop technique was performed and features contributing to potential phenotypic variation highlighted. Cultured HepG2 cells were seeded into Perfecta 3D® 96-well hanging drop plates and assessed over time for morphology, viability, cell cycle distribution, protein content and protein-mass profiles. Divergent aspects which were assessed included cell stocks, seeding density, volume of culture medium and use of extracellular matrix additives. Hanging drops are advantageous due to no complex culture matrix being present, enabling background free extractions for downstream experimentation. Varying characteristics were observed across cell stocks and batches, seeding density, culture medium volume and extracellular matrix when using immortalized HepG2 cells. These factors contribute to wide-ranging cellular responses and highlights concerns with respect to generating a reproducible phenotype in HepG2 hanging drop spheroids. Copyright © 2018 Elsevier Ltd. All rights reserved.

Melt segregation from silicic crystal mushes: a critical appraisal of possible mechanisms and their microstructural record

NASA Astrophysics Data System (ADS)

Holness, Marian B.

2018-06-01

One of the outstanding problems in understanding the behavior of intermediate-to-silicic magmatic systems is the mechanism(s) by which large volumes of crystal-poor rhyolite can be extracted from crystal-rich mushy storage zones in the mid-deep crust. The mechanisms commonly invoked are hindered settling, micro-settling, and compaction. The concept of micro-settling involves extraction of grains from a crystal framework during Ostwald ripening and has been shown to be non-viable in the metallic systems for which it was originally proposed. Micro-settling is also likely to be insignificant in silicic mushes, because ripening rates are slow for quartz and plagioclase, contact areas between grains in a crystal mush are likely to be large, and abundant low-angle grain boundaries promote grain coalescence rather than ripening. Published calculations of melt segregation rates by hindered settling (Stokes settling in a crystal-rich system) neglect all but fluid dynamical interactions between particles. Because tabular silicate minerals are likely to form open, mechanically coherent, frameworks at porosities as high as 75%, settling of single crystals is only likely in very melt-rich systems. Gravitationally-driven viscous compaction requires deformation of crystals by either dissolution-reprecipitation or dislocation creep. There is, as yet, no reported microstructural evidence of extensive, syn-magmatic, internally-generated, viscous deformation in fully solidified silicic plutonic rocks. If subsequent directed searches do not reveal clear evidence for internally-generated buoyancy-driven melt segregation processes, it is likely that other factors, such as rejuvenation by magma replenishment, gas filter-pressing, or externally-imposed stress during regional deformation, are required to segregate large volumes of crystal-poor rhyolitic liquids from crustal mushy zones.

Thermal annihilation of photo-induced radicals following dynamic nuclear polarization to produce transportable frozen hyperpolarized 13C-substrates

PubMed Central

Capozzi, Andrea; Cheng, Tian; Boero, Giovanni; Roussel, Christophe; Comment, Arnaud

2017-01-01

Hyperpolarization via dynamic nuclear polarization (DNP) is pivotal for boosting magnetic resonance imaging (MRI) sensitivity and dissolution DNP can be used to perform in vivo real-time 13C MRI. The type of applications is however limited by the relatively fast decay time of the hyperpolarized spin state together with the constraint of having to polarize the 13C spins in a dedicated apparatus nearby but separated from the MRI magnet. We herein demonstrate that by polarizing 13C with photo-induced radicals, which can be subsequently annihilated using a thermalization process that maintains the sample temperature below its melting point, hyperpolarized 13C-substrates can be extracted from the DNP apparatus in the solid form, while maintaining the enhanced 13C polarization. The melting procedure necessary to transform the frozen solid into an injectable solution containing the hyperpolarized 13C-substrates can therefore be performed ex situ, up to several hours after extraction and storage of the polarized solid. PMID:28569840

Dispersive liquid-liquid microextraction based on solidification of floating organic drop for preconcentration and determination of trace amounts of copper by flame atomic absorption spectrometry.

PubMed

Karadaş, Cennet; Kara, Derya

2017-04-01

A novel, simple, rapid, sensitive, inexpensive and environmentally friendly dispersive liquid-liquid microextraction method based on the solidification of a floating organic drop (DLLME-SFO) was developed for the determination of copper by flame atomic absorption spectrometry (FAAS). N-o-Vanillidine-2-amino-p-cresol was used as a chelating ligand and 1-undecanol was selected as an extraction solvent. The main parameters affecting the performance of DLLME-SFO, such as sample pH, volume of extraction solvent, extraction time, concentration of the chelating ligand, salt effect, centrifugation time and sample volume were investigated and optimized. The effect of interfering ions on the recovery of copper was also examined. Under the optimum conditions, the detection limit (3σ) was 0.93μgL -1 for Cu using a sample volume of 20mL, yielding a preconcentration factor of 20. The proposed method was successfully applied to the determination of Cu in tap, river and seawater, rice flour and black tea samples as well as certified reference materials. Copyright © 2016. Published by Elsevier Ltd.

Preconcentration of lead using solidification of floating organic drop and its determination by electrothermal atomic absorption spectrometry

PubMed Central

Chamsaz, Mahmoud; Akhoundzadeh, Jeiran; Arbab-zavar, Mohammad Hossein

2012-01-01

A simple microextraction method based on solidification of a floating organic drop (SFOD) was developed for preconcentration of lead prior to its determination by electrothermal atomic absorption spectrometry (ETAAS). Ammonium pyrolidinedithiocarbamate (APDC) was used as complexing agent, and the formed complex was extracted into a 20 μL of 1-undecanol. The extracted complex was diluted with ethanol and injected into a graphite furnace. An orthogonal array design (OAD) with OA16 (45) matrix was employed to study the effects of different parameters such as pH, APDC concentration, stirring rate, sample solution temperature and the exposure time on the extraction efficiency. Under the optimized experimental conditions the limit of detection (based on 3 s) and the enhancement factor were 0.058 μg L−1 and 113, respectively. The relative standard deviation (RSD) for 8 replicate determinations of 1 μg L−1 of Pb was 8.8%. The developed method was validated by the analysis of certified reference materials and was successfully applied to the determination of lead in water and infant formula base powder samples. PMID:25685441

Experimental Determination of the H2O-undersaturated Peridotite Solidus

NASA Astrophysics Data System (ADS)

Sarafian, E. K.; Gaetani, G. A.; Hauri, E.; Sarafian, A.

2015-12-01

Knowledge of the H2O-undersaturated lherzolite solidus places important constraints on the process of melt generation beneath oceanic spreading centers. While it is generally accepted that the small concentration of H2O (~50-200 ug/g) dissolved in the oceanic upper mantle has a strong influence on the peridotite solidus, but this effect has not been directly determined through experiments. This is because (1) precisely controlling low concentrations of H2O in high-pressure melting experiments is thought to be difficult, (2) small amounts of melt are difficult to identify, and (3) the size of mineral grains that grow in near-solidus experiments is too small to be analyzed for H2O by either Fourier transform infrared (FTIR) spectroscopy or secondary ion mass spectrometry (SIMS). We have developed an experimental approach for determining the peridotite solidus as a function of H2O content that overcomes these difficulties. Our approach utilizes large (~300 um diameter) spheres of San Carlos olivine to monitor the concentration and behavior of H2O in our experiments.. The spheres are mixed in 5:95 proportions with a synthetic peridotite that has the composition of the depleted MORB mantle of Workman and Hart (2005). Partial melting experiments are conducted in is a piston cylinder device using pre-conditioned Au80Pd20 capsules. During an experiment, the H2O content of the San Carlos olivine spheres diffusively equilibrates with the peridotite matrix. After each experiment, the concentration of H2O dissolved in the olivine spheres is determined by secondary ion mass spectrometry. By analyzing the H2O content of the San Carlos olivine spheres and performing a simple mass balance, we can then calculate the amount of H2O in the capsule. The spheres also provides a means to determine the solidus temperature due to the strong partitioning of H2O into silicate melt compared to olivine, pyroxene, and spinel. When a small amount of melt is present the H2O partitions into the melt and the H2O content of the spheres drops in a predictable fashion. The H2O-undersaturated solidus indicated by our experimental results is in agreement with previous experimental determinations of the nominally anhydrous solidus. This suggests that the potential temperature of the oceanic upper mantle is higher than existing petrologic estimates.

An Interconnected Network of Core-Forming Melts Produced by Shear Deformation

NASA Technical Reports Server (NTRS)

Bruhn, D.; Groebner, N.; Kohlstedt, D. L.

2000-01-01

The formation mechanism of terrestrial planetary is still poorly understood, and has been the subject of numerous experimental studies. Several mechanisms have been proposed by which metal-mainly iron with some nickel-could have been extracted from a silicate mantle to form the core. Most recent models involve gravitational sinking of molten metal or metal sulphide through a partially or fully molten mantle that is often referred to as a'magma ocean. Alternative models invoke percolation of molten metal along an interconnected network (that is, porous flow) through a solid silicate matrix. But experimental studies performed at high pressures have shown that, under hydrostatic conditions, these melts do not form an interconnected network, leading to the widespread assumption that formation of metallic cores requires a magma ocean. In contrast, here we present experiments which demonstrate that shear deformation to large strains can interconnect a significant fraction of initially isolated pockets of metal and metal sulphide melts in a solid matrix of polycrystalline olivine. Therefore, in a dynamic (nonhydrostatic) environment, percolation remains a viable mechanism for the segregation and migration of core-forming melts in a solid silicate mantle.

Organic components in hair-ice

NASA Astrophysics Data System (ADS)

Hofmann, Diana; Steffen, Bernhard; Disko, Ulrich; Wagner, Gerhard; Mätzler, Christian

2013-04-01

Hair-ice is a rather unknown phenomenon. In contrast to generally known frost needles, originating from atmospheric water and expanding e.g. from plant surfaces in all directions, hair ice grows from the basis of wet, rotten hardwood. The hair-like, flexible, linear structures may reach up to 10 cm in length without any ramifications. Hair-ice appears to be related to the biological activity of a fungus mycelium within the wood. Hair-ice can attract winter-active Collemboles (snow flea, Isotoma nivalis). At the onset of hair-ice melt a very thin fibre becomes apparent, which carries brownish pearl-like water drops. Therefore, it is supposed that organic substances are inherent, which could possibly act as freezing catalyst as well as recrystallization inhibitor. The aim of this work was the chemical characterization of organic substances contained in hair-ice. First analyses of melted hair-ice show a total organic carbon (TOC) value of 235 mg/l in contrast to 11 mg/l total nitrogen. Most of inherent nitrogen (70 %) exists thereby as ammonium. Screened by different (mass spectrometric) methods, no evidence could be found for the initially expected organic substances like proteins, lipids, small volatile substances or carboxylic acids. By coupling of Ultra Performance Liquid Chromatography with a triple quadrupol mass spectrometer (UPLC-MS) a non-resolved chromatogram from a melted hair-ice sample was received. Averaged spectra from different regions are similar among themselves with a broad peak spreading over the mass range 100-650 Da with favored intense, odd-numbered peaks. Such spectra are similar to dissolved organic matter (DOM), known e.g. from terrestrial and marine waters, soil extracts or aerosols. In the next step, samples were desalted and concentrated by solid phase extraction (SPE) and subsequently analyzed by flow injection analysis (FIA) in a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FTICR-MS), equipped with an ESI source and a 7 T supra-conducting magnet (LTQ-FT Ultra, ThermoFisher Scientific). This technique is the key technique for the analysis of complex samples due to its outstanding mass resolution (used 400.000 at m/z 400 Da) and mass accuracy (≤ 1 ppm), simultaneously providing molecular level details of thousands of compounds. The characteristics of the FTICR-MS hair-ice spectra with as many as ten or more peaks at each nominal mass are discussed together with highly resolved spectra from water and soil samples different sources, respectively. Complete manual formula assignment for structure elucidation would be extremely time consuming, therefore, we used an automated post processing based on SciLab for exploitation of the data with the aim of an unambiguous assignment of as many peaks as possible. Once the formulae had been assigned, the obtained mass lists were first checked randomly and afterwards transformed into Excel format for further post-processing and description. Most important is the van Krevelen diagram, usually two-dimensional as atomic ratio H/C versus atomic ratio O/C, widely used to classify samples regarding polarity and aromaticity. By comparison with two references (Hockaday 2007, Sleighter 2007), which arranged various biopolymer substance classes in such Van Krevelen plots, lignin could be detected as the main hair-ice component.

Formulation Optimization of Hot Melt Extruded Abuse Deterrent Pellet Dosage Form Utilizing Design of Experiments (DOE)

PubMed Central

Maddineni, Sindhuri; Battu, Sunil Kumar; Morott, Joe; Majumdar, Soumyajit; Repka, Michael A.

2014-01-01

The objective of the present study was to develop techniques for an abuse-deterrent (AD) platform utilizing hot melt extrusion (HME) process. Formulation optimization was accomplished by utilizing Box-Behnken design of experiments to determine the effect of the three formulation factors: PolyOx™ WSR301, Benecel™ K15M, and Carbopol 71G; each of which was studied at three levels on TR attributes of the produced melt extruded pellets. A response surface methodology was utilized to identify the optimized formulation. Lidocaine Hydrochloride was used as a model drug, and suitable formulation ingredients were employed as carrier matrices and processing aids. All of the formulations were evaluated for the TR attributes such as particle size post-milling, gelling, percentage of drug extraction in water and alcohol. All of the DOE formulations demonstrated sufficient hardness and elasticity, and could not be reduced into fine particles (<150µm), which is a desirable feature to prevent snorting. In addition, all of the formulations exhibited good gelling tendency in water with minimal extraction of drug in the aqueous medium. Moreover, Benecel™ K15M in combination with PolyOx™ WSR301 could be utilized to produce pellets with TR potential. HME has been demonstrated to be a viable technique with a potential to develop novel abuse-deterrent formulations. PMID:24433429

Dynamic melting in plume heads: the formation of Gorgona komatiites and basalts

NASA Astrophysics Data System (ADS)

Arndt, Nicholas T.; Kerr, Andrew C.; Tarney, John

1997-01-01

The small Pacific island of Gorgona, off the coast of Colombia, is well known for its spectacular spinifex-textured komatiites. These high-Mg liquids, which have been linked to a late Cretaceous deep mantle plume, are part of a volcanic series with a wide range of trace-element compositions, from moderately enriched basalts ( La/SmN ˜ 1.5) to extremely depleted ultramafic tuffs and picrites ( La/SmN ˜ 0.2). Neither fractional crystallization, nor partial melting of a homogeneous mantle source, can account for this large variation: the source must have been chemically heterogeneous. Low 143Nd/144Nd in the more enriched basalts indicates some initial source heterogeneity but most of the variation in magma compositions is believed to result from dynamic melting during the ascent of a plume. Modelling of major- and trace-element compositions suggests that ultramafic magmas formed at ˜ 60-100 km depth, and that the melt extraction that gave rise to their depleted sources started at still greater depths. The ultra-depleted lavas represent magmas derived directly from the hottest, most depleted parts of the plume; the more abundant moderately depleted basalts are interpreted as the products of pooling of liquids from throughout the melting region.

Experimental process investigation of a latent heat energy storage system with a staggered heat exchanger with different phase change materials for solar thermal energy storage applications

NASA Astrophysics Data System (ADS)

Tsolakoglou, Nikolas P.; Koukou, Maria K.; Vrachopoulos, Michalis Gr.; Tachos, Nikolaos; Lymberis, Kostas; Stathopoulos, Vassilis

2017-11-01

This work investigates melting and solidification processes of four different Phase Change Materials (PCM) used as latent heat thermal storage system. The experimental rig was consisted of an insulated tank, filled with the under investigation PCM, a staggered heat exchanger to supply or extract heat from the PCM cavity and a water pump to circulate Heat Transfer Fluid (HTF). Both charging (melting) and discharging (solidification) processes were conducted for two different HTF flow rates. The main scope of this work was to develop a first approach and to investigate the behaviour of PCM under various load conditions (different HTF flow rates). Results show that different HTF flow rates affect melting and solidification time periods; in both processes time was reduced while HTF flow rate was increased but in differentways due to the transition from conduction to convection heat transfer mechanisms.

Construction of Gallium Point at NMIJ

NASA Astrophysics Data System (ADS)

Widiatmo, J. V.; Saito, I.; Yamazawa, K.

2017-03-01

Two open-type gallium point cells were fabricated using ingots whose nominal purities are 7N. Measurement systems for the realization of the melting point of gallium using these cells were built. The melting point of gallium is repeatedly realized by means of the measurement systems for evaluating the repeatability. Measurements for evaluating the effect of hydrostatic pressure coming from the molten gallium existing during the melting process and the effect of gas pressure that fills the cell were also performed. Direct cell comparisons between those cells were conducted. This comparison was aimed to evaluate the consistency of each cell, especially related to the nominal purity. Direct cell comparison between the open-type and the sealed-type gallium point cell was also conducted. Chemical analysis was conducted using samples extracted from ingots used in both the newly built open-type gallium point cells, from which the effect of impurities in the ingot was evaluated.

High-Resolution Melting (HRM) of Hypervariable Mitochondrial DNA Regions for Forensic Science.

PubMed

Dos Santos Rocha, Alípio; de Amorim, Isis Salviano Soares; Simão, Tatiana de Almeida; da Fonseca, Adenilson de Souza; Garrido, Rodrigo Grazinoli; Mencalha, Andre Luiz

2018-03-01

Forensic strategies commonly are proceeding by analysis of short tandem repeats (STRs); however, new additional strategies have been proposed for forensic science. Thus, this article standardized the high-resolution melting (HRM) of DNA for forensic analyzes. For HRM, mitochondrial DNA (mtDNA) from eight individuals were extracted from mucosa swabs by DNAzol reagent, samples were amplified by PCR and submitted to HRM analysis to identify differences in hypervariable (HV) regions I and II. To confirm HRM, all PCR products were DNA sequencing. The data suggest that is possible discriminate DNA from different samples by HRM curves. Also, uncommon dual-dissociation was identified in a single PCR product, increasing HRM analyzes by evaluation of melting peaks. Thus, HRM is accurate and useful to screening small differences in HVI and HVII regions from mtDNA and increase the efficiency of laboratory routines based on forensic genetics. © 2017 American Academy of Forensic Sciences.

Experimental modeling of the interaction of subducted carbonates and sulfur with mantle silicates

NASA Astrophysics Data System (ADS)

Bataleva, Yu. V.; Palyanov, Yu. N.; Borzdov, Yu. M.; Zdrokov, E. V.; Sobolev, N. V.

2016-09-01

Experimental studies in the system Fe,Ni-olivine-carbonate-S ( P = 6.3 GPa, T = 1050-1550°C, t = 40-60 h) aimed at modeling of the interaction of subducted carbonates and sulfur with rocks of the silicate mantle and at investigation of the likely mechanism of the formation of mantle sulfides were performed. It is shown that an association of olivine + orthopyroxene + magnesite + pyrite coexisting with a sulfur melt/fluid with dissolved Fe, Ni, and O is formed at T ≤ 1250°C. An association of low-Fe olivine, orthopyroxene, and magnesite and two immiscible melts of the carbonate and S-Fe-Ni-O compositions are formed at T ≥ 1350°C. It is shown that the reduced S-bearing fluids may transform silicates and carbonates, extract metals from the solid-phase matrix, and provide conditions for generation of sulfide melts.

A comparison of the effects of Nd:YAG and Ho:YAG laser irradiation on dentine and enamel.

PubMed

Cernavin, I

1995-04-01

This preliminary study was undertaken to investigate the effects of Nd:YAG and Ho:YAG lasers on enamel and dentine of extracted teeth. The Ho:YAG laser (spot size 250 microns, energy density 4160 J/cm2) produced a cleaner puncture in dentine with less melting of the surrounding tissue than did the Nd:YAG laser (spot size 20 microns), energy density 50,000 J/cm2), which produced considerable melting and recrystallization of dentine and was more difficult to control. It was possible to cut enamel and dentine with both lasers, but considerable melted and recrystallized enamel was produced. From the limited observations of this study it appears that the Ho:YAG laser is more suitable for cutting both enamel and dentine than the Nd:YAG laser. More work needs to be done to ascertain the effect on enamel and dentine of modification of the parameters of both lasers.

Recycle polymer characterization and adhesion modeling

NASA Astrophysics Data System (ADS)

Holbery, James David

Contaminants from paper product producers that adversely affect fiber yield have been collected from mills located in three North American geographic regions. Samples have been fractionated using a modified solvent extraction process and subsequently quantitatively characterized and it was found that agglomerates were comprised of the following: approximately 30% extractable polymeric material, 25--35% fiber, 12--15% inorganic material, 15% non-extractable high molecular-weight polyethylene or cross-linked polymers, and 2--4% starch residue. Three representative polymers, paraffin, low-molecular weight polyethylene, and a commercial hot-melt adhesive were selected for further analysis to model the attractive and repulsive behavior using Scanning Probe Microscopy in an aqueous cell. Scanning force probes were characterized using an original technique utilizing a nano-indentation apparatus that is non-destructive and is accurate to within 10% for probes with force constants as low as 1 N/m. Surface force measurements were performed between a Poly (Styrene/30% Butyl Methacrylate) sphere and substrates produced from paraffin, polyethylene, and a commercial hot-melt adhesive in solutions ranging in NaF ionic concentrations from 0.001M to 1M. Reasonable theoretical agreement with experimental data has been shown between a combined model applying van der Waals force contributions using the Derjaguin approximation and electrostatic contributions as predicted by a Debye-Huckel linearization of the Poisson-Boltzmann equation utilizing Hamaker constants derived from critical surface energies determined from Zisman and Lifshitz-van der Waals energy approaches. This model has been applied to measured data and indicates the strength of adhesion for the hot-melt to be 0.14 nN while that of paraffin is 1.9 nN and polyethylene 2.8 nN. Paraffin and polyethylene are 13.5 and 20 times greater in attraction than the hot-melt adhesive. Hot-melt adhesive repulsion is predicted to be 220 pN while for paraffin it is 9.1 nN and polyethylene 12.2 nN, a factor of 41 and 55 greater for paraffin and polyethylene, respectively. Decay lengths for repulsion is fit to be 2.3 nm for hotmelt indicating, approximately one-third that of paraffin and polyethylene. Johnson-Kendall-Roberts contact mechanic theory for viscoelastic materials has been applied with reasonable accuracy, particularly in experiments performed in solutions, to model the approach snap-in magnitude and detachment forces between sphere and substrate. Two representative commercial agglomeration formulations have been analyzed to determine the impact on adhesion and detachment forces although at room temperature, no measurable effect was identified.

Experimental study of Gas Phase Formation and Evolution in Low fO2 Planetary Basalts.

NASA Astrophysics Data System (ADS)

Rutherford, M. J.; Wetzel, D. T.; Saal, A. E.; Hauri, E. H.

2012-12-01

The existence of a gas phase in planetary basaltic magmas is demonstrated by the ubiquitous presence of vesicles in returned lunar samples and meteorites as well as basalts from Earth and Mars. Additionally, formation of the fine-grained glass bead deposits during eruption of lunar picritic glasses required a large gas-bubble volume (> 90%) at the time of eruption/fragmentation. Up to 100-200 ppm levels of H, S, Cl and F still remain as diffusion-loss profiles in individual lunar glass beads SIMS (1), and higher volatile concentrations occur in olivine melt inclusions (2). The composition and origin of such volcanic gases were investigated by experiments on a volatile (C-O-H-S-Cl-F)-bearing picritic glass composition as a function of fO2 near iron-wustite (IW). The C-O-H species dissolved in gas-saturated basaltic melt above IW-0.5 are carbonate, OH and H2O with 100 to 10,000 ppm H2O in the sample; below IW-0.5, the C-species present (Raman and FTIR) are Fe(CO)5 (iron pentacarbonyl) and lesser CH4 [3]. The change in melt speciation in part reflects a change in calculated speciation in the coexisting gas [4]. The carbon solubility in these experimental melts increases linearly with increasing pressure; the more oxidized glasses contain 32-620 ppm C for pressures of 98 to 980 MPa, the reduced glasses contain 8-240 ppm C for pressures between 36 and 900 MPa. Thus, the C solubility of the more reduced Fe-carbonyl and CH4 is about one-half that of carbonate at the same pressure, and indicates the carrying capacity for C in reduced (i.e., lunar) magmas is much lower than it is in present day terrestrial magmas. Varioles up to 200 um in diameter formed in some experiments with higher dissolved water contents (1%); they have radiating crystalline textures (olivine, glass and poorly crystallized graphite) initiated at a central nucleation site. A sharp peak in the variole Ramen spectra indicates methane as well as CO is released during variole formation and a reaction such as 2CO = C +CO2 formed the graphite. Several series of experiments on chips of low fO2 glass created at high pressure quantify S, Cl and F partitioning into the H2O-CO gas phase with decompression steps from 200 to 40 MPa. A gas formed with the first pressure drop, indicating melt supersaturation with CO and/or CH4; H2O and lesser amounts of S, Cl and F partitioned into the initial gas, and continued to do so with additional drops in pressure. The ubiquitous Fe-metal seen in lunar picritic glasses may form by graphite oxidation, but also may form by breakdown of Fe(CO)5 as the melt continues to saturate during ascent. [1] A. E. Saal et al.(2008) Nature 454, 192-195. [2] E. H. Hauri et al (2011) Science 333, 213 -215. [3] Wetzel, D., Rutherford, M.J. Jacobsen S.D., Hauri, E.H., and Saal, A.E., (submitted); Nature Geoscience Aug. 1, 2012. [4] Zhang, C. and Duan, Z. (2009) GCA, 73, 2089-2102.

Slab-derived metasomatism in the Carpathian-Pannonian mantle revealed by investigations of mantle xenoliths from the Bakony-Balaton Highland Volcanic Field

NASA Astrophysics Data System (ADS)

Créon, Laura; Delpech, Guillaume; Rouchon, Virgile; Guyot, François

2017-08-01

A suite of fifteen peridotite xenoliths from the Bakony-Balaton Highland Volcanic Field (BBHVF, Pannonian Basin, Central Europe) that show abundant petrographic evidence of fluid and melt percolation were studied in order to decipher the formation of their melt pockets and veins. The suite mainly consists of "fertile" lherzolites (5.8-19.9 vol.% clinopyroxene) and a few harzburgites (1.9-5.4 vol.% clinopyroxene) from well-known localities (Szentbékkálla, Szigliget) and two previously unreported localities (Füzes-tó and Mindszentkálla). Major and trace element data indicate that most of the peridotites record variable degrees of partial melt extraction, up to > 15% for the harzburgites. Subsequently, the xenoliths experienced at least two stages of metasomatic modification. The first stage was associated with percolation of a volatile-bearing silicate melt and resulted in crystallization of amphibole, enrichment in the most incompatible trace elements (Ba, Th, U, Sr), and development of negative Nb-Ta anomalies in clinopyroxene. The second and last metasomatic event, widespread beneath the BBHVF, is associated with the formation of silicate melt pockets, physically connected to a network of melt veins, with large and abundant CO2 vesicles. The glass in these veins has sub-alkaline trachy-andesitic composition and displays an OIB-like trace element signature. Its composition attests to the migration through a supra-subduction zone mantle wedge of silicic melt highly enriched in volatiles (CO2, H2O, Cl, F), LILE, REE and HFSE and consistent with compositions of natural and experimental examples of slab melting-derived magma. In the present case, however, melt was likely derived from melting of oceanic crust and carbonated sediments under conditions where Nb-rich mineral phases were not stable in the residue. A likely scenario for the origin such melts involves melting after subduction ceased as the slab thermally equilibrated with the asthenosphere. Melt-rock reactions due to ascent of hot, CO2-rich, siliceous melt to near-Moho depths triggered destabilization of amphibole and primary clinopyroxene, spinel, and possibly olivine. The resulting andesitic glass in melt pockets evolved to more mafic compositions due to mantle mineral assimilation but has heterogeneous trace element signatures mostly inherited from preexisting amphibole. The present example of melt-rock reactions between highly volatile-enriched siliceous slab-derived melt and peridotite from the upper part of the lithospheric mantle ultimately produced derivative melt with major element composition akin to calc-alkaline basaltic andesite, with generally low trace elements concentrations but selective pronounced enrichments in LILE's such as Ba, Sr, Pb.

Groundwater resources vulnerability due to melting glaciers in the Talgar alluvian fan, northern Tien-Shan

NASA Astrophysics Data System (ADS)

Saks, Tomas; Timuhins, Andrejs; Sennikovs, Juris; Ibraimov, Vitaliy; Sotnikov, Evgeniy; Salybekova, Valentina; Rahimov, Timur; Popovs, Konrads

2017-04-01

Alluvial fans on the mountain slopes in Central Asia are an important source of the groundwater, due to there capacity of storing large quantities of the fresh groundwater and due to the fact that most urban centres are situated in the mountainous terrain or along mountain slopes. The groundwater resources in the alluvial fans are replenished by the infiltration from the rivers, which drain the mountain catchments and by infiltration from the precipitation, and released on there lower reaches as a series of seasonal springs or infiltrated into the lower lying aquifers. The rivers with there catchments in the mountainous terrain are fed by the precipitation (with the peak in May-June due to snow melt) and glacier melt. The glacier meltwater constitutes up to 90% of the river runoff in July-August, due to peak in glacier melt and low precipitation, providing much needed freshwater for agriculture in the dry season. In this study an attempt to quantify the importance of the glacier meltwater on the groundwater resources through groundwater modelling in the Talgar alluvial fan, Ili-Alatau mountain range has been performed. The results suggest that glacier meltwater is a substantial portion of the groundwater resources in the Talgar alluvial fan, with up to 30m drop of the groundwater level, if the glaciers disappear, endangering existing groundwater supply. The transient simulations suggest that disappearance of the glaciers and highly variable annual precipitation would result in highly fluctuating groundwater levels, as well as disappearance of most of the springs at the foot of the alluvial fan. These results are especially relevant for the northern Tien-Shan, where glaciers have been rapidly retreating over last 50 years, and some of the glaciers could disappear in next decades.

Corneal cross-linking in 9 horses with ulcerative keratitis

PubMed Central

2013-01-01

Background Corneal ulcers are one of the most common eye problems in the horse and can cause varying degrees of visual impairment. Secondary infection and protease activity causing melting of the corneal stroma are always concerns in patients with corneal ulcers. Corneal collagen cross-linking (CXL), induced by illumination of the corneal stroma with ultraviolet light (UVA) after instillation of riboflavin (vitamin B2) eye drops, introduces crosslinks which stabilize melting corneas, and has been used to successfully treat infectious ulcerative keratitis in human patients. Therefore we decided to study if CXL can be performed in sedated, standing horses with ulcerative keratitis with or without stromal melting. Results Nine horses, aged 1 month to 16 years (median 5 years) were treated with a combination of CXL and medical therapy. Two horses were diagnosed with mycotic, 5 with bacterial and 2 with aseptic ulcerative keratitis. A modified Dresden-protocol for CXL could readily be performed in all 9 horses after sedation. Stromal melting, diagnosed in 4 horses, stopped within 24 h. Eight of nine eyes became fluorescein negative in 13.5 days (median time; range 4–26 days) days after CXL. One horse developed a bacterial conjunctivitis the day after CXL, which was successfully treated with topical antibiotics. One horse with fungal ulcerative keratitis and severe uveitis was enucleated 4 days after treatment due to panophthalmitis. Conclusions CXL can be performed in standing, sedated horses. We did not observe any deleterious effects attributed to riboflavin or UVA irradiation per se during the follow-up, neither in horses with infectious nor aseptic ulcerative keratitis. These data support that CXL can be performed in the standing horse, but further studies are required to compare CXL to conventional medical treatment in equine keratitis and to optimize the CXL protocol in this species. PMID:23803176

Seasonal Change in Bacterial Flora and Biomass in Mountain Snow from the Tateyama Mountains, Japan, Analyzed by 16S rRNA Gene Sequencing and Real-Time PCR

PubMed Central

Segawa, Takahiro; Miyamoto, Koji; Ushida, Kazunari; Agata, Kiyokazu; Okada, Norihiro; Kohshima, Shiro

2005-01-01

The bacterial flora and biomass in mountain snow from the Tateyama Mountains, Toyama Prefecture, Japan, one of the heaviest snowfall regions in the world, were analyzed by amplified ribosomal DNA restriction analysis followed by 16S rRNA gene sequencing and DNA quantification by real-time PCR. Samples of surface snow collected in various months during the melting season contained a psychrophilic bacterium, Cryobacterium psychrophilum, and two psychrotrophic bacteria, Variovorax paradoxus and Janthinobacterium lividum. Bacterial colonies that developed in an in situ meltwater medium at 4°C were revealed to be V. paradoxus. The biomasses of C. psychrophilum, J. lividum, and V. paradoxus, as estimated by real-time PCR, showed large increases during the melting season from March to October (2.0 × 105-fold, 1.5 × 105-fold, and 1.0 × 104-fold increases, respectively), suggesting their rapid growth in the surface snow. The biomasses of C. psychrophilum and J. lividum increased significantly from March to April, reached a maximum in August, and dropped at the end of the melting season. In contrast, the biomass of V. paradoxus did not increase as rapidly during the early melting season but continued to increase from June until October. The differences in development observed among these bacterial species suggest that their growth was promoted by different nutrients and/or environmental conditions in the snow. Since these three types of bacteria have also been reported to be present in a glacier in Antarctica and a Greenland ice core, they seem to be specialized members of the snow biota that are distributed in snow and ice environments in various parts of the world. PMID:15640179

Seasonal change in bacterial flora and biomass in mountain snow from the Tateyama Mountains, Japan, analyzed by 16S rRNA gene sequencing and real-time PCR.

PubMed

Segawa, Takahiro; Miyamoto, Koji; Ushida, Kazunari; Agata, Kiyokazu; Okada, Norihiro; Kohshima, Shiro

2005-01-01

The bacterial flora and biomass in mountain snow from the Tateyama Mountains, Toyama Prefecture, Japan, one of the heaviest snowfall regions in the world, were analyzed by amplified ribosomal DNA restriction analysis followed by 16S rRNA gene sequencing and DNA quantification by real-time PCR. Samples of surface snow collected in various months during the melting season contained a psychrophilic bacterium, Cryobacterium psychrophilum, and two psychrotrophic bacteria, Variovorax paradoxus and Janthinobacterium lividum. Bacterial colonies that developed in an in situ meltwater medium at 4 degrees C were revealed to be V. paradoxus. The biomasses of C. psychrophilum, J. lividum, and V. paradoxus, as estimated by real-time PCR, showed large increases during the melting season from March to October (2.0 x 10(5)-fold, 1.5 x 10(5)-fold, and 1.0 x 10(4)-fold increases, respectively), suggesting their rapid growth in the surface snow. The biomasses of C. psychrophilum and J. lividum increased significantly from March to April, reached a maximum in August, and dropped at the end of the melting season. In contrast, the biomass of V. paradoxus did not increase as rapidly during the early melting season but continued to increase from June until October. The differences in development observed among these bacterial species suggest that their growth was promoted by different nutrients and/or environmental conditions in the snow. Since these three types of bacteria have also been reported to be present in a glacier in Antarctica and a Greenland ice core, they seem to be specialized members of the snow biota that are distributed in snow and ice environments in various parts of the world.

Floods of April-June 1952 in Utah and Nevada

USGS Publications Warehouse

Wells, J.V.B.

1957-01-01

The floods of April-June 1952 in the Great Basin and in the Green River basin in Utah came as the result of the heaviest snow cover recorded, a long period of near-record subnormal temperature during March and early April, and an abrupt change to above-normal temperature that induced rapid melting.Rainfall played an insignificant part. Low- and intermediate-elevation snow melted, bringing many streams to record-high level. Large diurnal fluctuations of discharge were evident on smaller streams. The temperature remained high until mid-May. As high-elevation snow became primed for runoff, the temperature dropped enough to refreeze and alter the structure of snow cover, thus reducing the effectiveness of the subsequent melting temperature. Had there been no respite from melting temperatures much greater peak discharges would have occurred, with damage greatly exceeding that experienced. Streams remained at high levels for several weeks.Record peaks were reached on Strawberry River, lower Weber River, Ogden River, Spanish Fork, lower Provo River, and Jordan River in Utah; Humboldt River and its tributaries draining the north area of the basin in Nevada; and the central Bear River in Idaho and Wyoming. Record volumes for the water year were measured on many streams in the northcentral part of Utah, the northeastern part of Nevada, and the central part of the Bear River basin in Idaho and Wyoming. Damage in the Great Basin reached \\$10 million and in the Green River basin, more than$300,000. Two lives were lost on Ogden River. The greatest urban damage, in Salt Lake City, totaled \\$1.9 million; the greatest single damage, to Denver and Rio Grande Western Railroad, was \\$510,000.

Trace Elements in Basalts From the Siqueiros Fracture Zone: Implications for Melt Migration Models

NASA Astrophysics Data System (ADS)

Pickle, R. C.; Forsyth, D. W.; Saal, A. E.; Nagle, A. N.; Perfit, M. R.

2008-12-01

Incompatible trace element (ITE) ratios in MORB from a variety of locations may provide insights into the melt migration process by constraining aggregated melt compositions predicted by mantle melting and flow models. By using actual plate geometries to create a 3-D thermodynamic mantle model, melt volumes and compositions at all depths and locations may be calculated and binned into cubes using the pHMELTS algorithm [Asimow et al., 2004]. These melts can be traced from each cube to the surface assuming several migration models, including a simplified pressure gradient model and one in which melt is guided upwards by a low permeability compacted layer. The ITE ratios of all melts arriving at the surface are summed, averaged, and compared to those of the actual sample compositions from the various MOR locales. The Siqueiros fracture zone at 8° 20' N on the East Pacific Rise (EPR) comprises 4 intra-transform spreading centers (ITSCs) across 140 km of offset between two longer spreading ridges, and is an excellent study region for several reasons. First, an abundance of MORB data is readily available, and the samples retrieved from ITSCs are unlikely to be aggregated in a long-lived magma chamber or affected by along-axis transport, so they represent melts extracted locally from the mantle. Additionally, samples at Siqueiros span a compositional range from depleted to normal MORB within the fracture zone yet have similar isotopic compositions to samples collected from the 9-10° EPR. This minimizes the effect of assuming a uniform source composition in our melting model despite a heterogeneous mantle, allowing us to consistently compare the actual lava composition with that predicted by our model. Finally, it has been demonstrated with preliminary migration models that incipient melts generated directly below an ITSC may not necessarily erupt at that ITSC but migrate laterally towards a nearby ridge due to enhanced pressure gradients. The close proximity of the ITSCs at Siqueiros to the large ridges bounding the fracture zone provide a good opportunity to model this phenomenon and may help explain the variable ITE ratios found between samples collected within the transform and those near the ridges.

187Os/188Os in Spinel Peridotites from Borée, Massif Central, France: Seeing through the Effects of Melt Infiltration in the Sub-continental Lithospheric Mantle

NASA Astrophysics Data System (ADS)

Barnett, C. J.; Harvey, J.

2015-12-01

The Re-Os isotope system can be used to model the timing of melt extraction in peridotites, although secondary metasomatic processes can obscure primary melt depletion signatures, implying that bulk-rock Os model ages should be treated with caution.1Spinel peridotites from the volcanic Maar de Borée (French Massif Central) have equigranular to protogranular and occasionally poikilitic textures. Their bulk-rock chemistry are consistent with moderate degrees of partial melting, but elevated incompatible trace element ratios (e.g. La/YbN) are indicative of subsequent secondary processes. Petrographic observation reveals no infiltration of host basalt, but melt infiltration unrelated to the host basalt has occurred, most likely within the sub-continental lithospheric mantle prior to entrainment as xenoliths. The peridotites have a mean [Os] concentration of 2.35 ng g-1 and 187Os/188Os values from 0.12081 ± 16 to 0.12639 ± 14 (cf. PUM = 0.1296 ± 00082), with rhenium depletion model ages (TRD) ranging from 0.48 to 1.30 Ga. Silicate melt contains up to 2 orders of magnitude less Os than peridotites3 but the 187Os/188Os of melt infiltrated peridotite can be skewed by the precipitation of immiscible sulfide when an infiltrating melt reaches S-saturation4. The Borée peridotites retain an unradiogenic Os-isotope signature despite silicate melt infiltration; this may be due to primary base metal sulfides enclosed in silicate minerals and therefore protected from interaction with infiltrating melts. TRD of enclosed sulphides should therefore be able to 'see through' any secondary metasomatic events and reveal melt depletion ages significantly older than those obtained from bulk-rock analyses (cf. 4). 1. Rudnick & Walker (2009) Lithos 112S, 1083-1095. 2. Meisel et al. (2001) Geochim Cosmochim Ac 65, 1311-1323. 3. Day, J.M.D. (2013) Chem Geol 341, 50-74. 4. Harvey et al. (2010) Geochim Cosmochim Acta 74, 293-320.

Silicate melts density, buoyancy relations and the dynamics of magmatic processes in the upper mantle

NASA Astrophysics Data System (ADS)

Sanchez-Valle, Carmen; Malfait, Wim J.

2016-04-01

Although silicate melts comprise only a minor volume fraction of the present day Earth, they play a critical role on the Earth's geochemical and geodynamical evolution. Their physical properties, namely the density, are a key control on many magmatic processes, including magma chamber dynamics and volcanic eruptions, melt extraction from residual rocks during partial melting, as well as crystal settling and melt migration. However, the quantitative modeling of these processes has been long limited by the scarcity of data on the density and compressibility of volatile-bearing silicate melts at relevant pressure and temperature conditions. In the last decade, new experimental designs namely combining large volume presses and synchrotron-based techniques have opened the possibility for determining in situ the density of a wide range of dry and volatile-bearing (H2O and CO2) silicate melt compositions at high pressure-high temperature conditions. In this contribution we will illustrate some of these progresses with focus on recent results on the density of dry and hydrous felsic and intermediate melt compositions (rhyolite, phonolite and andesite melts) at crustal and upper mantle conditions (up to 4 GPa and 2000 K). The new data on felsic-intermediate melts has been combined with in situ data on (ultra)mafic systems and ambient pressure dilatometry and sound velocity data to calibrate a continuous, predictive density model for hydrous and CO2-bearing silicate melts with applications to magmatic processes down to the conditions of the mantle transition zone (up to 2773 K and 22 GPa). The calibration dataset consist of more than 370 density measurements on high-pressure and/or water-and CO2-bearing melts and it is formulated in terms of the partial molar properties of the oxide components. The model predicts the density of volatile-bearing liquids to within 42 kg/m3 in the calibration interval and the model extrapolations up to 3000 K and 100 GPa are in good agreement with results from ab initio calculations. The density model has been applied to examine the mineral-melt buoyancy relations at depth and the implications of these results for the dynamics of magma chambers, crystal settling and the stability and mobility of magmas in the upper mantle will be discussed.

Melting and Its Influence on the Long-term Evolution of the Lower Mantle Heterogeneities (LLSVP and ULVZ)

NASA Astrophysics Data System (ADS)

Fomin, I.; Tackley, P. J.

2017-12-01

Recent investigations have shown mantle solidus close to the range of proposed core-mantle boundary (CMB) temperatures (e.g. [Andrault et al., 2011, 2014], [de Koker et al., 2013]). Certain fraction of distinct rocks may reduce the effective melting temperature to values below the CMB temperature. It is especially true for iron enriched materials such as MORB [Nomura et al., 2011], BIF [Kato et al., 2016], iron-rich periclase [Boukare et al., 2015] and other rock species used to explain observed seismic anomalies. Computer simulations allow to study evolution and stability for chemically distinct piles proposed from geophysical data. Previous researches (e.g. [Mulyukova et al., 2015]) found those piles stirring in several hundreds of Ma. Our investigation adds influence of melting and following chemical differentiation on preservation of such structures.We present StagYY code [Tackley et al., 2008] with extended set of routines to model melting, melt redistribution and melt-dependent rheology in addition to solid-state mantle convection to reveal fate of chemically distinct piles in long-term (millions of years) perspective. A new point of our approach is usage of chemically independent oxides to describe rock composition and physical properties. Thin layers homogenize in few tens of millions of years despite whether melting happens or not. Thick structures (like periclase piles proposed for ULVZ [Wicks et al., 2010] or MORB-bearing domes for LLSVP [Ohta et al., 2008]) undergo partial melting if CMB temperature is above 3700K. Melt migration results in extraction of fusible components and therefore segregation of iron-enriched material. However, we weren't able to obtain any stabilized layer of iron-rich partially molten material at the CMB, because ongoing interaction and reequilibration of melt and solid results in buoyant liquids spreading to the adjacent mantle. Rheological influence of melt on bulk rock properties reduces time pile can exist.Our modeling puts severe constraints on the presence and fate of chemical heterogeneities in the lowermost mantle. Melting enhances stirring of such heterogeneities and generally no silicate melt can be stabilized at CMB for long time. Only low CMB temperatures (generally lower than 3700 K) allow anomalies to exist for geological periods of time (hundreds of Ma).

Headspace single drop microextraction versus dispersive liquid-liquid microextraction using magnetic ionic liquid extraction solvents.

PubMed

An, Jiwoo; Rahn, Kira L; Anderson, Jared L

2017-05-15

A headspace single drop microextraction (HS-SDME) method and a dispersive liquid-liquid microextraction (DLLME) method were developed using two tetrachloromanganate ([MnCl 4 2- ])-based magnetic ionic liquids (MIL) as extraction solvents for the determination of twelve aromatic compounds, including four polyaromatic hydrocarbons, by reversed phase high-performance liquid chromatography (HPLC). The analytical performance of the developed HS-SDME method was compared to the DLLME approach employing the same MILs. In the HS-SDME approach, the magnetic field generated by the magnet was exploited to suspend the MIL solvent from the tip of a rod magnet. The utilization of MILs in HS-SDME resulted in a highly stable microdroplet under elevated temperatures and long extraction times, overcoming a common challenge encountered in traditional SDME approaches of droplet instability. The low UV absorbance of the [MnCl 4 2- ]-based MILs permitted direct analysis of the analyte enriched extraction solvent by HPLC. In HS-SDME, the effects of ionic strength of the sample solution, temperature of the extraction system, extraction time, stir rate, and headspace volume on extraction efficiencies were examined. Coefficients of determination (R 2 ) ranged from 0.994 to 0.999 and limits of detection (LODs) varied from 0.04 to 1.0μgL -1 with relative recoveries from lake water ranging from 70.2% to 109.6%. For the DLLME method, parameters including disperser solvent type and volume, ionic strength of the sample solution, mass of extraction solvent, and extraction time were studied and optimized. Coefficients of determination for the DLLME method varied from 0.997 to 0.999 with LODs ranging from 0.05 to 1.0μgL -1 . Relative recoveries from lake water samples ranged from 68.7% to 104.5%. Overall, the DLLME approach permitted faster extraction times and higher enrichment factors for analytes with low vapor pressure whereas the HS-SDME approach exhibited better extraction efficiencies for analytes with relatively higher vapor pressure. Copyright © 2017 Elsevier B.V. All rights reserved.

Oceanic mantle rocks reveal evidence for an ancient, 1.2-1.3 Ga global melting event

NASA Astrophysics Data System (ADS)

Dijkstra, A. H.; Sergeev, D.; McTaminey, L.; Dale, C. W.; Meisel, T. C.

2011-12-01

It is now increasingly being recognized that many oceanic peridotites are refertilized harzburgites, and that the refertilization often masks an extremely refractory character of the original mantle rock 'protolith'. Oceanic peridotites are, when the effects of melt refertilization are undone, often too refractory to be simple mantle melting residues after the extraction of mid-ocean ridge basalts at a spreading center. Rhenium-osmium isotope analysis is a powerful method to look through the effects of refertilization and to obtain constraints on the age of the melting that produced the refractory mantle protolith. Rhenium-depletion model ages of such anomalously refractory oceanic mantle rocks - found as abyssal peridotites or as mantle xenoliths on ocean islands - are typically >1 Ga, i.e., much older than the ridge system at which they were emplaced. In my contribution I will show results from two case studies of refertilized anciently depleted mantle rocks (Macquarie Island 'abyssal' peridotites and Lanzarote mantle xenoliths). Interestingly, very refractory oceanic mantle rocks from sites all around the world show recurring evidence for a Mesoproterozoic (~1.2-1.3 Ga) melting event [1]. Therefore, oceanic mantle rocks seem to preserve evidence for ancient melting events of global significance. Alternatively, such mantle rocks may be samples of rafts of ancient continental lithospheric mantle. Laser-ablation osmium isotope 'dating' of large populations of individual osmium-bearing alloys from mantle rocks is the key to better constrain the nature and significance of these ancient depletion events. Osmium-bearing alloys form when mantle rocks are melted to high-degrees. We have now extracted over >250 detrital osmium alloys from placer gold occurrences in the river Rhine. These alloys are derived from outcrops of ophiolitic mantle rocks in the Alps, which include blocks of mantle rocks emplaced within the Tethys Ocean, and ultramafic lenses of unknown (Precambrian?) age in the pre-Alpine Massifs. Populations of model ages of these Rhine alloys show prominent peaks at 0.5 and 1.2-1.3 Ga. The 1.2-1.3 Mesoproterozoic age peak recorded by the Rhine Os alloy population does also occur in Os alloy age distributions of other ophiolites worldwide, generally as a subsidiary peak [2]. In summary, osmium isotope model ages from mantle rocks and mantle-derived individual osmium alloys worldwide collectively point to a Mesoproterozoic, 1.2-1.3 Ga high-degree mantle melting event of global significance. This event may be related to a slab-avalanche or whole-mantle overturn event in Mesoproterozoic times. [1] Dijkstra et al. (2010) J. Petrology 51, 469-493 [2] Pearson et al. (2007) Nature 449, 202-205

Are ``Hot Spots'' Hot? - An Overview

NASA Astrophysics Data System (ADS)

Foulger, G. R.

2010-12-01

The term “hot spot” is taken variously to imply a) the presence of excessive volcanism, or b) that the melt formed in an unusually hot source. Case b) is intrinsic to the plume hypothesis. Temperature anomalies of 200-300 degrees Celsius are expected, though there is widespread downward-revision of this where observations do not support it. It is not self-evident that “hot spots” are hot in the sense of case b), despite the fact that this is widely assumed. Furthermore, a hot source is not strongly supported by observations, and is at odds with many data. The temperature of the mantle has been studied using many different methods. Global oceanic heat flow values were recently assessed, but reveal no evidence for elevated temperatures around proposed plume localities. Mapping surface heat flow is only sensitive to anomalies at the level of 100 degrees Celsius, however. Seismological methods include correlating velocity with crustal thickness at LIPs, measuring transition zone thickness, and mapping velocity, e.g., using tomography. The first of these does not find evidence for elevated temperatures. The latter two are both sensitive to the presence of partial melt and variations in rock composition, in addition to temperature, which is the weakest potential effect. They thus cannot be used as thermometers. In particular, it cannot be assumed that red = hot and blue = cold in tomographic cross sections. Petrological and geochemical approaches include the “global systematics”. This has now been shown to not work for estimating temperature and its application should be discontinued. Mineralogical phase relationships are applied by comparing data from laboratory melting experiments to observations. Olivine control-line analysis has been extensively used in attempts to measure the differences in melt-formation temperature between mid-ocean ridges and melting anomalies. Difficulties arise in choosing the correct olivine geothermometer and because picrite glass is lacking from any melting anomaly except Hawaii. The results must be compared with a measure of the temperature of “normal mantle”. This is usually taken to be the temperature of melt formation beneath mid-ocean ridges, but the correct choice is controversial. Furthermore, this cannot be assumed to represent the potential temperature of the mantle in general. The surface conduction layer may extend much deeper than the depth of extraction of MORB, so melt extracted from greater depths, e.g., from beneath the base of the lithosphere in old parts of the ocean basins, may form at higher temperatures. It is easier to assume that the mantle beneath “hot spots” is hot than it is to show unequivocally that it is true. This endeavor is perhaps the most direct way of testing the plume hypothesis, but it is also one of the most challenging.

Melting Conditions of Basaltic Volcanism from Collision to Escape in the Central Anatolian Volcanic Province

NASA Astrophysics Data System (ADS)

Maloney, P. M.; Reid, M. R.; Cosca, M. A.; Gencalioglu Kuscu, G.

2013-12-01

Both Miocene and Quaternary mafic volcanics have erupted in the vicinity of the present-day Central Anatolian fault zone since the cessation of Afro-Arabian subduction and continent-continent collision, and the initiation of tectonic escape. We report results for samples from the Central Anatolian Volcanic Province (near Hasan volcano) and the Sarkisla region of the Sivas basin (250 km NE of Hasandag) analyzed with the goal of understanding the melting conditions responsible for the post-collisional magmatism in these regions. New 40Ar/39Ar dates for basalts erupted near Hasan range in age from 2.58 +/- 0.08 Ma to 62 +/- 4 ka. A majority of the dates cluster at ~400 ka, ages similar to those documented by Notsu et al, 1995. These subalkaline basalts have Zn/Fe and FC3MS [(FeO*/CaO)-3x(MgO/SiO2)] concentrations (10.0-11.4 and 0.05-0.39, respectively) expected for basalts produced by melting of peridotite (Le Roux et al, 2011, Yang and Zhou, 2013). Using olivine-opx-melt thermobarometry (Lee et al, 2009), the samples are determined to have been extracted from the mantle at 1.2-1.8 GPa and 1314-1391 °C. Clinopyroxene thermobarometry (Putirka, 2003) shows that they then crystallized at 0.7 GPa and ~1200°C. Enrichments in LILE:HFSE, most likely imparted to the magmas from mantle lithosphere which has been enriched by previous subduction zone metasomatism, is present in all of the samples. Accordingly, basalts sampled near Hasan are derived from a shallow lithospheric mantle peridotite source that has been affected by Afro-Arabian subduction prior to collision. New 40Ar/39Ar dates for basanites and basalts from the Sarkisla region show that they erupted between 17.6 +/- 0.4 Ma and 14.09 +/- 0.09 Ma. They have elsewhere been reported to be Plio-Pleistocene in age (Parlak et al., 2001). Zn/Fe and FC3MS for these basalts (Zn/Fe: 10.4-12.6, FC3MS: 0.29-0.91) range to values above the maximum value produced by peridotite melts (~10.8 and 0.65, respectively). Therefore, olivine-poor lithologies may be abundant in the melting region. Basanites from Sarkisla were extracted at ~5.2 GPa and ~1590°C and then crystallized at 1.5 GPa and 1280 °C. However, since pyroxenite appears to be an important constituent in the melting region for the Sarkisla samples, this thermobarometer is not strictly applicable. The Sarkisla mafic lavas, in contrast to those near Hasan, have trace element signatures more similar to typical asthenospherically-derived lavas and thermobarometry points to deeper, asthenospheric melting conditions. Collectively, our results show that the melting conditions of mafic lavas associated with the Central Anatolian Fault have varied as the tectonic regime evolved over time.

Approaching the 2015 Arctic Sea Ice Minimum

NASA Image and Video Library

2017-12-08

As the sun sets over the Arctic, the end of this year’s melt season is quickly approaching and the sea ice cover has already shrunk to the fourth lowest in the satellite record. With possibly some days of melting left, the sea ice extent could still drop to the second or third lowest on record. Arctic sea ice, which regulates the planet’s temperature by bouncing solar energy back to space, has been on a steep decline for the last two decades. This animation shows the evolution of Arctic sea ice in 2015, from its annual maximum wintertime extent, reached on February 25, to September 6. Credit: NASA Scientific Visualization Studio DOWNLOAD THIS VIDEO HERE: svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=11999 NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Containerless electromagnetic levitation melting of Cu-Fe and Ag-Ni alloys

NASA Technical Reports Server (NTRS)

Abbaschian, G. J.; Ethridge, E. C.

1983-01-01

The feasibility of producing silver or copper alloys containing finely dispersed nickel or iron particles, respectively, by utilizing containerless electromagnetic levitation casting techniques was investigated. A levitation coil was designed to successfully levitate and melt a variety of alloys including Nb-Ge, Cu-Fe, Fe-C, and Ag-Ni. Samples of 70 Cu-30 Fe and 80 Ag-20 Ni (atomic %), prepared by mechanical pressing of the constituent powders, were levitated and heated either to the solid plus liquid range of the alloys or to the fully liquid region. The samples were then solidified by passing helium gas into the bell jar or they were dropped into a quenching oil. The structure of the samples which were heated to the solid plus liquid range consists of uniform distribution of Fe or Ni particle in their respective matrices. A considerable amount of entrapped gas bubbles were contained. Upon heating for longer periods or to higher temperatures, the bubbles coalesced and burst, causing the samples to become fragmented and usually fall out of the coil.

Phenomenological model of maize starches expansion by extrusion

NASA Astrophysics Data System (ADS)

Kristiawan, M.; Della Valle, G.; Kansou, K.; Ndiaye, A.; Vergnes, B.

2016-10-01

During extrusion of starchy products, the molten material is forced through a die so that the sudden abrupt pressure drop causes part of the water to vaporize giving an expanded, cellular structure. The objective of this work was to elaborate a phenomenological model of expansion and couple it with Ludovic® mechanistic model of twin screw extrusion process. From experimental results that cover a wide range of thermomechanical conditions, a concept map of influence relationships between input and output variables was built. It took into account the phenomena of bubbles nucleation, growth, coalescence, shrinkage and setting, in a viscoelastic medium. The input variables were the moisture content MC, melt temperature T, specific mechanical energy SME, shear viscosity η at the die exit, computed by Ludovic®, and the melt storage moduli E'(at T > Tg). The outputs of the model were the macrostructure (volumetric expansion index VEI, anisotropy) and cellular structure (fineness F) of solid foams. Then a general model was established: VEI = α (η/η0)n in which α and n depend on T, MC, SME and E' and the link between anisotropy and fineness was established.

The dynamics of the rapid solidification of two successive aluminum particles in molten state

NASA Astrophysics Data System (ADS)

Zirari, M.; El-Hadj, A. Abdellah; Bacha, N.

2013-12-01

A finite element method is used to simulate coating deposition in the thermal spraying process. The model uses a method based on a fixed-grid Eulerian control volume to solve the fluid dynamics and energy conservation equations. A volume-of-fluid algorithm was used to track free surface deformation. The specific heat method (SHM) is used for the solidification phenomenon. This work deals mainly numerically, the problem related to solidification during impact of two identical aluminium drops, impacting successively on the same point and time-shifted, onto a smooth steel substrate. In the first part of this study, a completely melted particle, sprayed onto substrate tool steel H13 is considered in the objective of identification. Then, we examine four possible cases of successive impacts of two particles and their effects on the sprawl dynamics in different states (fully and/or partially melted). It was found that the internal energy in conjunction with the metallurgical state of the droplet play a key role in the final morphology of the coating.

Ice nucleation triggered by negative pressure.

PubMed

Marcolli, Claudia

2017-11-30

Homogeneous ice nucleation needs supercooling of more than 35 K to become effective. When pressure is applied to water, the melting and the freezing points both decrease. Conversely, melting and freezing temperatures increase under negative pressure, i.e. when water is stretched. This study presents an extrapolation of homogeneous ice nucleation temperatures from positive to negative pressures as a basis for further exploration of ice nucleation under negative pressure. It predicts that increasing negative pressure at temperatures below about 262 K eventually results in homogeneous ice nucleation while at warmer temperature homogeneous cavitation, i. e. bubble nucleation, dominates. Negative pressure occurs locally and briefly when water is stretched due to mechanical shock, sonic waves, or fragmentation. The occurrence of such transient negative pressure should suffice to trigger homogeneous ice nucleation at large supercooling in the absence of ice-nucleating surfaces. In addition, negative pressure can act together with ice-inducing surfaces to enhance their intrinsic ice nucleation efficiency. Dynamic ice nucleation can be used to improve properties and uniformity of frozen products by applying ultrasonic fields and might also be relevant for the freezing of large drops in rainclouds.

Noncontact temperature measurement: Requirements and applications for metals and alloys research

NASA Technical Reports Server (NTRS)

Perepezko, J. H.

1988-01-01

Temperature measurement is an essential capability for almost all areas of metals and alloys research. In the microgravity environment many of the science priorities that have been identified for metals and alloys also require noncontact temperature measurement capability. For example, in order to exploit the full potential of containerless processing, it is critical to have available a suitable noncontact temperature measurement system. This system is needed to track continuously the thermal history, including melt undercooling and rapid recalescence, of relatively small metal spheres during free-fall motion in drop tube systems. During containerless processing with levitation-based equipment, accurate noncontact temperature measurement is required to monitor one or more quasi-static samples with sufficient spatial and thermal resolution to follow the progress of solidification fronts originating in undercooled melts. In crystal growth, thermal migration, coarsening and other experiments high resolution thermal maps would be a valuable asset in the understanding and modeling of solidification processes, fluid flows and microstructure development. The science and applications requirements place several constraints on the spatial resolution, response time and accuracy of suitable instrumentation.

Chemostratigraphy of Subduction Initiation: Boninite and Forearc Basalt from IODP Expedition 352

NASA Astrophysics Data System (ADS)

Shervais, John; Haugen, Emily; Godard, Marguerite; Ryan, Jeffrey G.; Prytulak, Julie; Li, Hongyan; Chapman, Timothy; Nelson, Wendy R.; Heaton, Daniel E.; Kirchenbaur, Maria; Shimizu, Kenji; Li, Yibing; Whattam, Scott A.; Almeev, Renat; Sakuyama, Tetsuya; Reagan, Mark K.; Pearce, Julian A.

2017-04-01

The Izu-Bonin forearc has been the focus of several recent IODP (International Ocean Discovery Program) expeditions studying the geophysical, petrologic, and chemical response to subduction initiation and its potential relationship to ophiolite genesis. IODP Expedition 352 cored four holes in the Izu-Bonin forearc near Chichi Jima in order to document the petrologic and chemical evolution of nascent subduction zones. Holes U1440 and U1441, drilled closest to the trench, sampled forearc basalt (FAB). U1439 and U1442, drilled stratigraphically up-section and farther from the trench, sampled boninite, high-Mg andesite, and basalt. FAB are characterized by MORB-like compositions, with relatively constant Ti, Zr, and Ti/Zr. In general, more primitive FAB are found in the lower part of the section. In detail, FAB have lower Na, Ti, P, and Zr, lower Ti/V ratios, and are LREE-depleted relative to MORB. Best fit models for the least evolved FAB and a depleted MORB mantle (DMM) source require extraction of 1% melt in the garnet lherzolite field and 19% melt extraction in the spinel lherzolite field (relative to 8-10% melt of DMM to produce MORB). Three types of boninite were found: high silica boninite (HSB), low silica boninite (LSB), and basaltic boninite (BB), as well as high Mg andesites (HMA). HSB, the youngest unit in both U1439 and U1442, is underlain by LSB-BB-HMA lavas, which often occur in mixed magma zones with evolved boninite and basalt. Boninites are distinguished by co-variations in SiO2-MgO and TiO2-MgO, and by Ti/Zr ratios, which increase from HSB through LSB to BB. HSB, LSB and BB define parallel trends in TiO2-MgO space: a low Ti trend represented by LSB and BB, and a lower Ti trend represented by HSB. All of the boninite suite rocks are slightly LREE-rich relative to MORB. LSB and BB have flat REE patterns relative to primitive mantle, whereas HSB are slightly LREE-rich. These trends require distinct source compositions in HSB relative to LSB/BB. The decrease in Ti/Zr from BB to HSB suggests a slab melt component. Melting models (non-modal, fractional) for boninites require additional partial melting of a residual source more depleted than DMM, and mixing with less depleted melts. The data require a heterogeneous source during subduction initiation, tapping progressively more refractory mantle through time, and showing progressive enrichment in slab components.

In Situ Resource Utilization (ISRU) Experiments for Mars Exploration

NASA Technical Reports Server (NTRS)

Marone, Matt

2005-01-01

In situ resource utilization can best be described as living off the land. In our case the land is the planet Mars. ISRU is based on the idea that some fraction of the consumables, life support and propellant materials do not have to be flown from earth. Rather, they can be manufactured or extracted from resources already present on Mars. The primary resources on Mars are the atmosphere, polar caps and regolith. The atmosphere of Mars is mostly carbon dioxide as shown in the table below. The proportion of oxygen on the other hand is quite small. Still, there is quite a bit of oxygen in the Martian atmosphere, but it is unfortunately tied up with carbon. Thus, one of the goals of ISRU is the separation of breathable oxygen from the carbon dioxide. Several means of separation have been proposed. We have begun experiments on another approach for production of oxygen with carbon monoxide as a useful by product. Our work on a CO2 separator is described later in this report. Regolith melting is another means of obtaining materials. Two materials of interest are iron and silicon. Iron oxide is plentiful on Mars and is of obvious importance for structural components. Silicon is the foundation of solid state devices. Power generation on Mars may be accomplished using silicon solar cells. There is discussion of the feasibility of in situ production of solar cells. This would require a means of extracting silicon from the regolith. We have conducted several experiments concerning melting and glassification of the Mars soil simulant. Other summer faculty fellows have tried various means of processing the stimulant material. These include furnace melting, microwave melting and laser ablation. We have conducted several furnace melting experiments in both air and carbon dioxide environments. We have also carried out experiments to test spark melting in a carbon dioxide atmosphere. These experiments suggest the possibility of using arc melting in a reducing atmosphere. It is important to keep in mind that we are working with a soil stimulant. Any simulant, no matter how chemically similar it is to Martian regolith, may differ in mineralogy. The underlying assumption in this work is that once a glass is formed, any differences between simulant and regolith are unimportant. The exact means of forming the glass do, however, depend on the mineralogy of the regolith. A sample return mission is required to help answer these questions.

Transition from single-jump type to highly cooperative diffusion during structural relaxation of a metallic glass

NASA Astrophysics Data System (ADS)

Rätzke, K.; Hüppe, P. W.; Faupel, F.

1992-04-01

The isotope effect E=(Dα/Dβ-1)/[(mβ/mα)1/2-1] of cobalt diffusion has been measured in melt-spun amorphous Co76.7Fe2Nb14.3B7 ribbon at different stages of structural relaxation. A drastic drop of the isotope effect from E>0.5 in the as-quenched glass to E=0.1 in the relaxed state wass observed. While the latter value relflects highly cooperative diffusion, the large isotope effect in the as-quenched ribbon points to the prevalence of single-atom jumps and vacancylike holes of excess volume.

The current role of on-line extraction approaches in clinical and forensic toxicology.

PubMed

Mueller, Daniel M

2014-08-01

In today's clinical and forensic toxicological laboratories, automation is of interest because of its ability to optimize processes, to reduce manual workload and handling errors and to minimize exposition to potentially infectious samples. Extraction is usually the most time-consuming step; therefore, automation of this step is reasonable. Currently, from the field of clinical and forensic toxicology, methods using the following on-line extraction techniques have been published: on-line solid-phase extraction, turbulent flow chromatography, solid-phase microextraction, microextraction by packed sorbent, single-drop microextraction and on-line desorption of dried blood spots. Most of these published methods are either single-analyte or multicomponent procedures; methods intended for systematic toxicological analysis are relatively scarce. However, the use of on-line extraction will certainly increase in the near future.

Antiviral activity in vitro of two preparations of the herbal medicinal product Sinupret® against viruses causing respiratory infections.

PubMed

Glatthaar-Saalmüller, B; Rauchhaus, U; Rode, S; Haunschild, J; Saalmüller, A

2011-12-15

Sinupret(®), a herbal medicinal product made from Gentian root, Primula flower, Elder flower, Sorrel herb, and Verbena herb is frequently used in the treatment of acute and chronic rhinosinusitis and respiratory viral infections such as common cold. To date little is known about its potential antiviral activity. Therefore experiments have been performed to measure the antiviral activity of Sinupret(®) oral drops (hereinafter referred to as "oral drops") and Sinupret(®) dry extract (hereinafter referred to as "dry extract"), in vitro against a broad panel of both enveloped and non-enveloped human pathogenic RNA and DNA viruses known to cause infections of the upper respiratory tract: influenza A, Chile 1/83 (H1N1) virus (FluA), Porcine Influenza A/California/07/2009 (H1N1) virus (pFluA), parainfluenza type 3 virus (Para 3), respiratory syncytial virus, strain Long (RSV), human rhinovirus B subtype 14 (HRV 14), coxsackievirus subtype A9 (CA9), and adenovirus C subtype 5 (Adeno 5). Concentration-dependent antiviral activity (EC(50) between 13.8 and 124.8 μg/ml) of Sinupret(®) was observed against RNA as well as DNA viruses independent of a viral envelope. Remarkable antiviral activity was shown against Adeno 5, HRV 14 and RSV in which dry extract was significantly superior to oral drops. This could be ascertained with different assays as plaque-reduction assays in plaque forming units (PFU), the analyses of a cytopathogenic effect (CPE) and with enzyme immunoassays (ELISA) to determine the amount of newly synthesised virus. Our results demonstrate that Sinupret(®) shows a broad spectrum of antiviral activity in vitro against viruses commonly known to cause respiratory infections. Copyright © 2011 Elsevier GmbH. All rights reserved.

Generation and emplacement of shear-related highly mobile crustal melts: the synkinematic leucogranites from the Variscan Tormes Dome, Western Spain

NASA Astrophysics Data System (ADS)

López-Moro, Francisco Javier; López-Plaza, Miguel; Romer, Rolf L.

2012-07-01

The Tormes dome consists of S-type granites that intruded into Ordovician augen gneisses and Neoproterozoic-Lower Cambrian metapelites/metagreywackes at different extents of migmatization. S-type granites are mainly equigranular two-mica granites, occurring as: (1) enclave-laden subvertical feeder dykes, (2) small external sill-like bodies with size and shape relations indicative for self-similar pluton growth, and (3) as large pluton bodies, emplaced at higher levels than the external ones. These magmas were highly mobile as it is inferred from the high contents of fluxing components, the disintegration and alignment of pelitic xenoliths in feeder dykes and at the bottom of some sill-like bodies. Field relations relate this 311 Ma magmatism (U-Pb monazite) to the regional shearing of the D3 Variscan event. Partial melting modeling and the relatively high estimated liquidus temperatures indicate biotite-dehydration partial melting (800-840°C and 400-650 MPa) rather than water-fluxed melting, implying that there was no partial melting triggered by externally derived fluids in the shear zones. Instead, the subvertical shear zones favored extraction of melts that formed during the regional migmatization event around 320 Ma. Nd isotope variation among the granites might reflect disequilibrium partial melting or different protoliths. Mass-balance and trace element partial melting modeling strongly suggest two kinds of fertile crustal protoliths: augen gneisses and metapelites. Slight compositional variation among the leucogranites does not reflect different extent of protolith melting but is related to a small amount of fractional crystallization (<13% for the equigranular granites), which is generally more pronounced in shallower batholitic leucogranites than in the small and homogeneous sill-like bodies. The lower extent of fractional crystallization and the higher-pressure emplacement conditions of the sill-like bodies support a more restricted movement through the crust than for batholitic leucogranites.

Thermochronological evolution of an intra-plate magmatic event inferred from an integrated modeling approach: A case study in the Westerwald, Germany

NASA Astrophysics Data System (ADS)

Tirone, M.; Rokitta, K.; Schreiber, U.

2016-09-01

A lava sample from the Tertiary Westerwald volcanic field was selected for a detailed study using various analytical techniques in combination with petrological, thermodynamic and diffusion modeling to extract information related to the thermochronological evolution of a magmatic event before eruption. The lava sample contains large olivine phenocrysts which are compositionally zoned and two coexisting but chemically distinct melts, a host melt with basaltic composition and small spherical pockets of a less abundant trachytic melt (globules). The sample was analyzed by electron microprobe, x-ray fluorescence (XRF) X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). The primary melt of the host lava was determined using the program PRIMELT2.XLS. Partial fractional crystallization of olivine was modeled using the program alphaMELTS. Timescale and cooling rate were retrieved by fitting the measured Fe-Mg zoning along two directions in four olivine grains from the host lava using a 3-D numerical diffusion model. The measured variation of Ca is also consistent with a chemical diffusion process, while a numerical growth model applied to the same olivines does not appear to explain the Fe-Mg zoning. Chemical zoning of major elements in the melt globules were reproduced with a multicomponent diffusion model. The results of this study show that the host magma fractionated about 9% of olivine in a first stage, then the crystallization proceeded without further separation of mineral phases. Modeling of diffusion in the olivine crystals suggests that this second stage lasted at least 5 yrs and the temperature of the melt decreased from 1120-1150 °C to 1090 °C during this time. According to the results of the multicomponent diffusion model applied to the melt globules, the coexistence of the two melts was extremely short (less than few hours), possibly recording the assimilation of the globules during eruption or cooling of the whole system on the surface.

Design of a micromachined terahertz electromagnetic crystals (EMXT) channel-drop filter on silicon-substrate

NASA Astrophysics Data System (ADS)

Zhou, Kai; Liu, Yong; Si, Liming; Lv, Xin

2013-08-01

An integrated 0.5 THz electromagnetic crystals(EMXT) channel-drop filter based on PBG structure is presented in this paper. A channel-drop filter is a device in which a narrow bandwidth is redirected to another "drop" waveguide while other frequencies are unaffected. It's capable of extracting a certain frequency from a continuous spectrum in the bus channel and passing it to the test channel. It has potential applications in photonic integrated circuits, radio astronomy, THz spectroscopy, THz communication and remote sensing radar receiver. PBG structures(or photonic crystals) are periodic structures which possess band gaps, where the electromagnetic wave of certain ranges of frequencies cannot pass through and is reflected. The proposed channel-drop filter consists of input waveguide,output waveguide and PBG structure. The proposed filter is simulated using the finite element method and can be fabricated by micro-electromechanical systems (MEMS) technology,due to its low cost, high performance and high processing precision.The filter operation principle and fabrication process are discussed.The simulation results show its ability to filter the frequency of 496GHz with a linewidth of approximately 4GHz and transmission of 27.2 dB above background.The loss at resonant frequency is less than 1dB considering the thickness and roughness of gold layer required by the MEMS process.The channel drop efficiency is 84%.

Optimization of gelatine extraction from grass carp (Catenopharyngodon idella) fish skin by response surface methodology.

PubMed

Kasankala, Ladislaus M; Xue, Yan; Weilong, Yao; Hong, Sun D; He, Qian

2007-12-01

To establish the optimum gelatine extraction conditions from grass carp fish skin, response surface methodology (RSM) was adopted in this study. The effects of concentration of HCl (%, A), pre-treatment time (h, B), extraction temperature ( degrees C, C) and extraction time (h, D) were studied. The responses were yield (%) and gel strength (g). A=1.19%, B=24 h, C=52.61 degrees C and D=5.12h were determined as the optimum conditions while the predicted responses were 19.83% yield and 267 g gel strength. Gelling and melting points were 19.5 degrees C and 26.8 degrees C, respectively. Moreover, grass carp gelatine showed high contents of imino acids (proline and hydroxyproline) 19.47%. RSM provided a powerful tool to optimize the extraction parameters and the results may be adapted for industrial extraction of gelatine from grass carp fish skins.

Simple, miniaturized blood plasma extraction method.

PubMed

Kim, Jin-Hee; Woenker, Timothy; Adamec, Jiri; Regnier, Fred E

2013-12-03

A rapid plasma extraction technology that collects a 2.5 μL aliquot of plasma within three minutes from a finger-stick derived drop of blood was evaluated. The utility of the plasma extraction cards used was that a paper collection disc bearing plasma was produced that could be air-dried in fifteen minutes and placed in a mailing envelop for transport to an analytical laboratory. This circumvents the need for venipuncture and blood collection in specialized vials by a phlebotomist along with centrifugation and refrigerated storage. Plasma extraction was achieved by applying a blood drop to a membrane stack through which plasma was drawn by capillary action. During the course of plasma migration to a collection disc at the bottom of the membrane stack blood cells were removed by a combination of adsorption and filtration. After the collection disc filled with an aliquot of plasma the upper membranes were stripped from the collection card and the collection disc was air-dried. Intercard differences in the volume of plasma collected varied approximately 1% while volume variations of less than 2% were seen with hematocrit levels ranging from 20% to 71%. Dried samples bearing metabolites and proteins were then extracted from the disc and analyzed. 25-Hydroxy vitamin D was quantified by LC-MS/MS analysis following derivatization with a secosteroid signal enhancing tag that imparted a permanent positive charge to the vitamin and reduced the limit of quantification (LOQ) to 1 pg of collected vitamin on the disc; comparable to values observed with liquid-liquid extraction (LLE) of a venipuncture sample. A similar study using conventional proteomics methods and spectral counting for quantification was conducted with yeast enolase added to serum as an internal standard. The LOQ with extracted serum samples for enolase was 1 μM, linear from 1 to 40 μM, the highest concentration examined. In all respects protein quantification with extracted serum samples was comparable to that observed with serum samples obtained by venipuncture.

High-resolution melting PCR analysis for rapid genotyping of Burkholderia mallei.

PubMed

Girault, G; Wattiau, P; Saqib, M; Martin, B; Vorimore, F; Singha, H; Engelsma, M; Roest, H J; Spicic, S; Grunow, R; Vicari, N; De Keersmaecker, S C J; Roosens, N H C; Fabbi, M; Tripathi, B N; Zientara, S; Madani, N; Laroucau, K

2018-05-08

Burkholderia (B.) mallei is the causative agent of glanders. A previous work conducted on single-nucleotide polymorphisms (SNP) extracted from the whole genome sequences of 45 B. mallei isolates identified 3 lineages for this species. In this study, we designed a high-resolution melting (HRM) method for the screening of 15 phylogenetically informative SNPs within the genome of B. mallei that subtype the species into 3 lineages and 12 branches/sub-branches/groups. The present results demonstrate that SNP-based genotyping represent an interesting approach for the molecular epidemiology analysis of B. mallei. Copyright © 2018 Elsevier B.V. All rights reserved.

Iron single crystal growth from a lithium-rich melt

NASA Astrophysics Data System (ADS)

Fix, M.; Schumann, H.; Jantz, S. G.; Breitner, F. A.; Leineweber, A.; Jesche, A.

2018-03-01

α -Fe single crystals of rhombic dodecahedral habit were grown from a Li84N12Fe∼3 melt. Crystals of several millimeter along a side form at temperatures around T ≈ 800 ° C. Upon further cooling the growth competes with the formation of Fe-doped Li3N. The b.c.c. structure and good sample quality of α -Fe single crystals were confirmed by X-ray and electron diffraction as well as magnetization measurements and chemical analysis. A nitrogen concentration of 90 ppm was detected by means of carrier gas hot extraction. Scanning electron microscopy did not reveal any sign of iron nitride precipitates.

Melt densities in the CaO-FeO-Fe 2O 3-SiO 2 system and the compositional dependence of the partial molar volume of ferric iron in silicate melts

NASA Astrophysics Data System (ADS)

Dingwell, Donald B.; Brearley, Mark

1988-12-01

The densities of 10 melts in the CaO-FeO-Fe 2O 3-SiO 2 system were determined in equilibrium with air, in the temperature range of 1200 to 1550°C, using the double-bob Archimedean technique. Melt compositions range from 6 to 58 wt% SiO 2, 14 to 76 wt% Fe 2O 3 and 10 to 46 wt% CaO. The ferric-ferrous ratios of glasses drop-quenched from loop fusion equilibration experiments were determined by 57Fe Mössbauer spectroscopy. Melt densities range from 2.689 to 3.618 gm/cm 3 with a mean standard deviation from replicate experiments of 0.15%. Least-squares regressions of molar volume versus molar composition have been performed and the root mean squared deviation shows that a linear combination of partial molar volumes for the oxide components (CaO, FeO, Fe 2O 3 and SiO 2) cannot describe the data set within experimental error. Instead, the inclusion of excess terms in CaFe 3+ and CaSi (product terms using the oxides) is required to yield a fit that describes the experimental data within error. The nonlinear compositional-dependence of the molar volumes of melts in this system can be explained by structural considerations of the roles of Ca and Fe 3+. The volume behavior of melts in this system is significantly different from that in the Na 2O-FeO-Fe 2O 3-SiO 2 system, consistent with the proposal that a proportion of Fe 3+ in melts in the CaO-FeO-Fe 2O 3-SiO 2 system is not tetrahedrally-coordinated by oxygen, which is supported by differences in 57Fe Mössbauer spectra of glasses. Specifically, this study confirms that the 57Fe Mössbauer spectra exhibit an area asymmetry and higher values of isomer shift of the ferric doublet that vary systematically with composition and temperature (this study; Dingwell and Virgo, 1987, 1988). These observations are consistent with a number of other lines of evidence ( e.g., homogeneous redox equilibria, Dickenson and Hess, 1986; viscosity, Dingwell and Virgo, 1987,1988). Two species of ferric iron, varying in proportions with temperature, composition and redox state, are sufficient to describe the above observations. The presence of more than one coordination geometry for Fe 3+ in low pressure silicate melts has several implications for igneous petrogenesis. The possible effects on compressibility, the pressure dependence of the redox ratio, and redox enthalpy are briefly noted.

DYNAMIC MECHANICAL STUDIES OF IRRADIATED POLYPROPYLENE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sauer, J.A.; Merrill, L.J.; Woodward, A.E.

1962-04-01

The internal friction and the dynamic modulus of isotactic polypropylene samples subject to varying degrees of pile irradiation were studied at low audio frequencies and over the temperature range from 100 to over 400 deg K. The radiation dosages used varied from 5.4 x lO/sup 17/ to 14 x lO/sup 18/ nvt. For irradiation doses up to about 3 x lO/sup 18/ nvt, one observed change is a decrease in the temperature at which the final upswing in damping and drop in modulus occurs, presumably as a result of defects produced in the crystallites by the irradiation. As the irradiationmore » dose increases above 3 x lO/sup 18/ nvt, all evidence of crystallinity is lost, and the internal friction peak which occurs in the neighborhood of 300 deg K and which is associated with the glass transition of the amorphous regions moves to higher temperatures as a result of the increasing chain-stiffening effect due to crosslinking. The secondary loss peak at 250 deg K attributed to the motion of a small number of segraents in the amorphous regions is found to increase in magnitude with increasing dose. The results of density determinations raade before and after irradiation and also after subsequent exposure of the irradiated samples to melting temperatures and of solvent extraction studies of the irradiated samples confirm the simultaneous occurrence of crosslinking and of crystalline degradation upon pile irradiation of polypropylene samples. (auth)« less

Derivation and calibration of a gas metal arc welding (GMAW) dynamic droplet model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reutzel, E.W.; Einerson, C.J.; Johnson, J.A.

1996-12-31

A rudimentary, existing dynamic model for droplet growth and detachment in gas metal arc welding (GMAW) was improved and calibrated to match experimental data. The model simulates droplets growing at the end of an imaginary spring. Mass is added to the drop as the electrode melts, the droplet grows, and the spring is displaced. Detachment occurs when one of two criteria is met, and the amount of mass that is detached is a function of the droplet velocity at the time of detachment. Improvements to the model include the addition of a second criterion for drop detachment, a more sophisticatedmore » model of the power supply and secondary electric circuit, and the incorporation of a variable electrode resistance. Relevant physical parameters in the model were adjusted during model calibration. The average current, droplet frequency, and parameter-space location of globular-to-streaming mode transition were used as criteria for tuning the model. The average current predicted by the calibrated model matched the experimental average current to within 5% over a wide range of operating conditions.« less

Highly siderophile element systematics of abyssal peridotites from intermediate and fast spreading ridges

NASA Astrophysics Data System (ADS)

Brown, D. B.; Day, J. M.; Waters, C. L.

2016-12-01

Abyssal peridotites are residues of both modern and ancient partial melt extraction at oceanic ridges and can be used to examine melting processes and mantle heterogeneity. The highly siderophile elements (HSE: Os, Ir, Ru, Pt, Pd, Re, and the 187Re-187Os system embedded within them), are useful for investigating these issues, as they are generally strongly compatible. To date, limited data on HSE and Os isotopes has been obtained on abyssal peridotites from fast spreading centers. Here, we report new HSE abundance and 187Os/188Os data for Pacific Antarctic Ridge (PAR) and East Pacific Rise (EPR) abyssal peridotites. Samples from the PAR were dredged from two separate localities along the Udintsev Fracture Zone, and EPR samples were taken from Hess Deep. The PAR full spreading rate ranges from 54-83mm/year [1,2] and is 75 mm/year [2] at the Udintsev Fracture Zone. These spreading rates characterize the PAR as an intermediate spreading ridge, whereas the fast spreading EPR has a full rate ranging from 128-157 mm/year [3]. The 187Os/188Os ratios for whole-rocks from the PAR range from 0.114 to 0.134, with Re depletion ages (TRD) varying from 1 Ga to present. Despite the large variation in 187Os/188Os, HSE patterns are primitive mantle-like [4], with Ru/Ir ratios ranging from 1.5-2.1. Depletions in Re and Pd are present, as is expected in partial melt residues, and the samples have undergone 4-15% partial melting based on the rare earth elements (REE). The EPR exhibits higher levels of melt depletion ranging from 18-24%. New results show Hess Deep samples have 187Os/188Os ratios of 0.123 and 0.125 for whole-rocks. These findings indicate that PAR and EPR Os isotopic data overlap with the global record of abyssal peridotites from slower ridges and that Os isotopic heterogeneities are preserved across a wide range of spreading rates and degrees of melt extraction. [1] Géli, L., et al. (1997), Science, 278, 1281-1284; [2] Castillo, P.R., et al. (1998) EPSL, 154,109-125; [3] Warren, J.M., (2016) Lithos, 248-251, 193-219; [4] Becker, H., et al. (2006) GCA, 70, 4528-4550

Evolution of the Campanian Ignimbrite Magmatic System I: Constraints on Compositional Zonation and Eruption Probability Imposed By Phase Equilibria

NASA Astrophysics Data System (ADS)

Fowler, S.; Spera, F.; Bohrson, W.; Belkin, H.; Devivo, B.

2005-12-01

The eruption and deposition of the ~39.3 ka Campanian Ignimbrite (CI), a large volume (~200 km3 DRE) trachytic to phonolitic ignimbrite, is the dominant event in the history of the Campi Flegrei volcanic field near Naples, Italy. In an effort to comprehend its petrological evolution, we have conducted ~~110 MELTS (Ghiorso, 1997) phase equilibria simulations of the major element evolution of parental CI magma. The goals of this work are to approximate oxygen fugacity (fO2), initial dissolved water content and pressure at which isobaric closed system fractional crystallization of parental melt most accurately captures the observed liquid line of descent and to study the implications of heat extraction from parental CI magma with respect to the origin of compositional zonation and the probability of explosive eruption. Although the CI magma body did not evolve as a perfectly closed system, this assumption allows quantitative insight into magma-host rock mass exchange using trace element and isotopic data (see companion contribution by Bohrson et al.). The parental melt composition was reconstructed using data for melt inclusions trapped within CI clinopyroxene phenocrysts reported by Webster et al. (2003), while allowing for reaction between parental melt and clinopyroxene host. The inferred parental melt is a basaltic trachyandesite. The search space for pressure, (fO2) and initial dissolved H2O was 0.1-0.5 in 0.05 GPa increments, QFM-1 to QFM+3 and 1, 2 and 3 wt. % H2O, respectively. The criteria used to judge the quality of a simulation include correspondence of the MELTS prediction with CI liquid and phenocryst compositions. Results indicate that a good first-order model involves evolution from a basaltic trachyandesite parent by isobaric (~0.15 GPa) crystal fractionation initially containing ~3 wt% dissolved H2O along the QFM+1 buffer. H2O first saturates at 1127°C at 0.15 GPa when the dissolved water content is ~4 wt %. A striking result is the discovery of a pseudo-invariant point at ~883°C (Tip) and 0.15 GPa. The fraction of melt changes abruptly from ~0.5 to ~0.1 at Tip due to the simultaneous crystallization of alkali feldspar, plagioclase, spinel, biotite and apatite. At Tip, there is a dramatic decrease in the viscosity of melt (by a factor of four) and magma density (~5%) and an increase in the dissolved H2O content of the melt (from 4.4-5.1 wt%) and in the volume fraction,θ, of supercritical fluid in the multiphase system. In particular, θ increases from ~0.05 at 885°C to ~0.6 at 882°C. The liquid composition also changes discontinuously at Tip with Si, Na, and H2O increasing and K and Al decreasing as temperature falls below Tip. The marked variations in composition and properties of volatile-saturated melt and magma were the trigger that led to the catastrophic eruption and formation of the compositionally-zoned CI magma. Because phase equilibria modeling provides information on the enthalpy changes associated with fractional crystallization and because the dimensions of the CI magma chamber and heat extraction rate can be approximated, a time scale for CI magmatic evolution can be derived. The estimated crystallization duration (τ) is10-100 ka and 75% of τ is spent at or near Tip.

Relating surface roughness and magnetic domain structure to giant magneto-impedance of Co-rich melt-extracted microwires

DOE PAGES

Jiang, S. D.; Eggers, T.; Thiabgoh, O.; ...

2017-04-11

Understanding the relationship between the surface conditions and giant magneto-impedance (GMI) in Co-rich melt-extracted microwires is key to optimizing their magnetic responses for magnetic sensor applications. The surface magnetic domain structure (SMDS) parameters of ~45 μm diameter Co 69.25Fe 4.25Si 13B 13.5-xZr x (x = 0, 1, 2, 3) microwires, including the magnetic domain period (d) and surface roughness (Rq) as extracted from the magnetic force microscopy (MFM) images, have been correlated with GMI in the range 1–1000 MHz. It was found that substitution of B with 1 at. % Zr increased d of the base alloy from 729 tomore » 740 nm while retaining Rq from ~1 nm to ~3 nm. A tremendous impact on the GMI ratio was found, increasing the ratio from ~360% to ~490% at an operating frequency of 40 MHz. Further substitution with Zr decreased the high frequency GMI ratio, which can be understood by the significant increase in surface roughness evident by force microscopy. Lastly, this study demonstrates the application of the domain period and surface roughness found by force microscopy to the interpretation of the GMI in Co-rich microwires.« less

Solidified Floating Organic Drop Microextraction for the Detection of Trace Amount of Lead in Various Samples by Electrothermal Atomic Absorption Spectrometry.

PubMed

Aydın Urucu, Oya; Dönmez, Şeyda; Kök Yetimoğlu, Ece

2017-01-01

A novel method was developed for determination of trace amounts of lead in water and food samples. Solidified floating organic drop microextraction was used to preconcentrate the lead ion. After the analyte was complexed with 1-(2-pyridylazo)-2-naphthol, undecanol and acetonitrile were added as extraction and dispersive solvent, respectively. Variables such as pH, volumes of extraction and dispersive solvents, and concentration of chelating agent were optimized. Under the optimum conditions, the detection limit of Pb (II) was determined as 0.042  µ g L -1 with an enrichment factor of 300. The relative standard deviation is <10%. Accuracy of the developed procedure was evaluated by the analysis of certified reference material of human hair (NCS DC 73347) and wastewater (SPS-WW2) with satisfactory results. The developed procedure was then successfully applied to biscuit and water samples for detection of Pb (II) ions.

Ionic liquid-based single-drop microextraction/gas chromatographic/mass spectrometric determination of benzene, toluene, ethylbenzene and xylene isomers in waters.

PubMed

Aguilera-Herrador, Eva; Lucena, Rafael; Cárdenas, Soledad; Valcárcel, Miguel

2008-08-01

The direct coupling between ionic liquid-based single-drop microextraction and gas chromatography/mass spectrometry is proposed for the rapid and simple determination of benzene, toluene, ethylbenzene and xylenes isomers (BTEX) in water samples. The extraction procedure exploits not only the high affinity of the selected ionic liquid (1-methyl-3-octyl-imidazolium hexaflourophosphate) to these aromatic compounds but also its special properties like viscosity, low vapour pressure and immiscibility with water. All the variables involved in the extraction process have been studied in depth. The developed method allows the determination of these single-ring compounds in water under the reference concentration level fixed by the international legislation. In this case, limits of detection were in the range 20 ng L(-1) (obtained for benzene) and 91 ng L(-1) (for o-xylene). The repeatability of the proposed method, expressed as RSD (n=5), varied between 3.0% (o-xylene) and 5.2% (toluene).

Air-assisted liquid-liquid microextraction using floating organic droplet solidification for simultaneous extraction and spectrophotometric determination of some drugs in biological samples through chemometrics methods

NASA Astrophysics Data System (ADS)

Farahmand, Farnaz; Ghasemzadeh, Bahar; Naseri, Abdolhossein

2018-01-01

An air assisted liquid-liquid microextraction by applying the solidification of a floating organic droplet method (AALLME-SFOD) coupled with a multivariate calibration method, namely partial least squares (PLS), was introduced for the fast and easy determination of Atenolol (ATE), Propanolol (PRO) and Carvedilol (CAR) in biological samples via a spectrophotometric approach. The analytes would be extracted from neutral aqueous solution into 1-dodecanol as an organic solvent, using AALLME. In this approach a low-density solvent with a melting point close to room temperature was applied as the extraction solvent. The emulsion was immediately formed by repeatedly pulling in and pushing out the aqueous sample solution and extraction solvent mixture via a 10-mL glass syringe for ten times. After centrifugation, the extractant droplet could be simply collected from the aqueous samples by solidifying the emulsion at a lower than the melting point temperature. In the next step, analytes were back extracted simultaneously into the acidic aqueous solution. Derringer and Suich multi-response optimization were utilized for simultaneous optimizing the parameters of three analytes. This method incorporates the benefits of AALLME and dispersive liquid-liquid microextraction considering the solidification of floating organic droplets (DLLME-SFOD). Calibration graphs under optimized conditions were linear in the range of 0.30-6.00, 0.32-2.00 and 0.30-1.40 μg mL- 1 for ATE, CAR and PRO, respectively. Other analytical parameters were obtained as follows: enrichment factors (EFs) were found to be 11.24, 16.55 and 14.90, and limits of detection (LODs) were determined to be 0.09, 0.10 and 0.08 μg mL- 1 for ATE, CAR and PRO, respectively. The proposed method will require neither a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly.

Air-assisted liquid-liquid microextraction using floating organic droplet solidification for simultaneous extraction and spectrophotometric determination of some drugs in biological samples through chemometrics methods.

PubMed

Farahmand, Farnaz; Ghasemzadeh, Bahar; Naseri, Abdolhossein

2018-01-05

An air assisted liquid-liquid microextraction by applying the solidification of a floating organic droplet method (AALLME-SFOD) coupled with a multivariate calibration method, namely partial least squares (PLS), was introduced for the fast and easy determination of Atenolol (ATE), Propanolol (PRO) and Carvedilol (CAR) in biological samples via a spectrophotometric approach. The analytes would be extracted from neutral aqueous solution into 1-dodecanol as an organic solvent, using AALLME. In this approach a low-density solvent with a melting point close to room temperature was applied as the extraction solvent. The emulsion was immediately formed by repeatedly pulling in and pushing out the aqueous sample solution and extraction solvent mixture via a 10-mL glass syringe for ten times. After centrifugation, the extractant droplet could be simply collected from the aqueous samples by solidifying the emulsion at a lower than the melting point temperature. In the next step, analytes were back extracted simultaneously into the acidic aqueous solution. Derringer and Suich multi-response optimization were utilized for simultaneous optimizing the parameters of three analytes. This method incorporates the benefits of AALLME and dispersive liquid-liquid microextraction considering the solidification of floating organic droplets (DLLME-SFOD). Calibration graphs under optimized conditions were linear in the range of 0.30-6.00, 0.32-2.00 and 0.30-1.40μg mL -1 for ATE, CAR and PRO, respectively. Other analytical parameters were obtained as follows: enrichment factors (EFs) were found to be 11.24, 16.55 and 14.90, and limits of detection (LODs) were determined to be 0.09, 0.10 and 0.08μg mL -1 for ATE, CAR and PRO, respectively. The proposed method will require neither a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly. Copyright © 2017 Elsevier B.V. All rights reserved.

Forced Oscillations of Supported Drops

NASA Technical Reports Server (NTRS)

Wilkes, Edward D.; Basaran, Osman A.

1996-01-01

Oscillations of supported liquid drops are the subject of wide scientific interest, with applications in areas as diverse as liquid-liquid extraction, synthesis of ceramic powders, growing of pure crystals in low gravity, and measurement of dynamic surface tension. In this research, axisymmetric forced oscillations of arbitrary amplitude of viscous liquid drops of fixed volume which are pendant from or sessile on a rod with a fixed or moving contact line and surrounded by an inviscid ambient gas are induced by moving the rod in the vertical direction sinusiodally in time. In this paper, a preliminary report is made on the computational analysis of the oscillations of supported drops that have 'clean' interfaces and whose contact lines remain fixed throughout their motions. The relative importance of forcing to damping can be increased by either increasing the amplitude of rod motion A or Reynolds number Re. It is shown that as the ratio of forcing to damping rises, for drops starting from an initial rest state a sharp increase in deformation can occur when they are forced to oscillate in the vicinity of their resonance frequencies, indicating the incipience of hysteresis. However, it is also shown that the existence of a second stable limit cycle and the occurrence of hysteresis can be observed if the drop is subjected to a so-called frequency sweep, where the forcing frequency is first increased and then decreased over a suitable range. Because the change in drop deformation response is abrupt in the vicinity of the forcing frequencies where hysteresis occurs, it should be possible to exploit the phenomenon to accurately measure the viscosity and surface tension of the drop liquid.

Development of a constant surface pressure penetration langmuir balance based on axisymmetric drop shape analysis.

PubMed

Wege, H A; Holgado-Terriza, J A; Cabrerizo-Vílchez, M A

2002-05-15

A new constant pressure pendant-drop penetration surface balance has been developed combining a pendant-drop surface balance, a rapid-subphase-exchange technique, and a fuzzy logic control algorithm. Beside the determination of insoluble monolayer compression-expansion isotherms, it allows performance of noninvasive kinetic studies of the adsorption of surfactants added to the new subphase onto the free surface and of the adsorption/penetration/reaction of the former onto/into/with surface layers, respectively. The interfacial pressure pi is a fundamental parameter in these studies: by working at constant pi one controls the height of the energy barrier to adsorption/penetration and can select different regimes and steps of the adsorption/penetration process. In our device a solution drop is formed at the tip of a coaxial double capillary, connected to a double microinjector. Drop profiles are extracted from digital drop micrographs and fitted to the equation of capillarity, yielding pi, the drop volume V, and the interfacial area A. pi is varied changing V (and hence A) with the microinjector. Control is based on a case-adaptable modulated fuzzy-logic PID algorithm able to maintain constant pi (or A) under a wide range of experimental conditions. The drop subphase liquid can be exchanged quantitatively by the coaxial capillaries. The adsorption/penetration/reaction kinetics at constant pi are then studied monitoring A(t), i.e., determining the relative area change necessary at each instant to compensate the pressure variation due to the interaction of the surfactant in the subsurface with the surface layer. A fully Windows-integrated program manages the whole setup. Examples of experimental protein adsorption and monolayer penetration kinetics are presented.

Development of a Smart Release Algorithm for Mid-Air Separation of Parachute Test Articles

NASA Technical Reports Server (NTRS)

Moore, James W.

2011-01-01

The Crew Exploration Vehicle Parachute Assembly System (CPAS) project is currently developing an autonomous method to separate a capsule-shaped parachute test vehicle from an air-drop platform for use in the test program to develop and validate the parachute system for the Orion spacecraft. The CPAS project seeks to perform air-drop tests of an Orion-like boilerplate capsule. Delivery of the boilerplate capsule to the test condition has proven to be a critical and complicated task. In the current concept, the boilerplate vehicle is extracted from an aircraft on top of a Type V pallet and then separated from the pallet in mid-air. The attitude of the vehicles at separation is critical to avoiding re-contact and successfully deploying the boilerplate into a heatshield-down orientation. Neither the pallet nor the boilerplate has an active control system. However, the attitude of the mated vehicle as a function of time is somewhat predictable. CPAS engineers have designed an avionics system to monitor the attitude of the mated vehicle as it is extracted from the aircraft and command a release when the desired conditions are met. The algorithm includes contingency capabilities designed to release the test vehicle before undesirable orientations occur. The algorithm was verified with simulation and ground testing. The pre-flight development and testing is discussed and limitations of ground testing are noted. The CPAS project performed a series of three drop tests as a proof-of-concept of the release technique. These tests helped to refine the attitude instrumentation and software algorithm to be used on future tests. The drop tests are described in detail and the evolution of the release system with each test is described.

The connection between crustal reworking and petrological diversity in the deep crust: clues from migmatites

NASA Astrophysics Data System (ADS)

Carvalho, Bruna B.; Sawyer, Edward W.; de Assis Janasi, Valdecir

2016-04-01

The deep levels of the continental crust have been extensively reworked as result of crustal differentiation. Migmatites are widespread in these high-grade metamorphic terrains, and provide valuable information on how processes such as partial melting, segregation of the melt from the residue and subsequent chemical exchanges lead to the petrological diversity found in the deep crust. This study investigates processes that transformed a largely uniform, metagranodiorite protolith into a very complex migmatite that contains three varieties of diatexites (grey, schlieren and homogenous diatexites) and several types of leucosomes. The Kinawa Migmatite is part of the Archean TTG crust in the São Francisco Craton (Brazil), which has been reworked in a shear zone environment at upper amphibolite facies conditions (<730°C and 5-6 kbar); thus it may be typical of crustal reworking in the interior of old cratons [1]. Grey diatexites are residual rocks formed by the extraction of a water-fluxed melt created via the reaction Pl + Kfs + Qz + H2O = melt. Diversity within the grey diatexites arises from different degrees of melt segregation (maximum ~40% melt). Schlieren diatexites are very heterogeneous rocks in which residuum-rich domains alternate with leucocratic quartzo-feldspathic domains where melt accumulated. Homogeneous diatexites are coarse-grained leucocratic rocks and represent larger bodies of anatectic melt with minor amounts (<20%) of entrained residuum. Leucosomes display a wide range of compositions from tonalitic to alkali-feldspar granite. Leucosomes, homogeneous diatexites and the quartzo-feldspathic domains in the schlieren diatexites all show a sequence of microstructural stages from plagioclase-dominated to K-feldspar-dominated frameworks many of which show evidence for tectonic compaction. Thus, further segregation of melt from solids occurred during crystallization. Minor amphibolite dykes in the metagranodiorite did not melt. They occur as angular to rounded fragments (schollen or rafts) in the diatexites and show strong evidence for mechanical and chemical interaction with their melt rich hosts. Typically, the diatexites and the leucosomes around the schollen contain higher proportion of amphibole and/or biotite than that farther away; a number of features suggest that this is due to disaggregation that contaminated the melt rich rocks. Our data indicates that in the deep levels of the crust petrological diversity is produced by melt segregation, both during partial melting and crystallization, and by interaction of the anatectic melt with unmelted material in the source. During melting, segregation produced residuum plus anatectic melt and all intermediate stages, whereas during crystallization it resulted in crystal fractionation and generated diverse plagioclase-rich rocks and fractionated melts. Finally, crystals disaggregated from the amphibolites entrained and interact with anatectic melt producing leucosomes and diatexites with the compositional signature of contamination. [1] Carvalho, B.B; Sawyer, E.W.; Janasi, V.A. (2016). Crustal reworking in a shear zone: transformation of metagranite to migmatite. Journal of Metamorphic Geology DOI: 10.1111/jmg.12180

Drop dynamics on a thin film: Thin film rupture

NASA Astrophysics Data System (ADS)

Carlson, Andreas; Kim, Pilnam; Stone, Howard A.

2011-11-01

The spreading of a water drop on an oil film that covers a solid substrate is a common event in many industrial processes. We study in experiments the dynamics of a water drop on a thin silicone oil film and quantify its interaction with the solid substrate that supports the film. The oil film becomes unstable and ruptures for solids that are hydrophilic. We determine the ``waiting time,'' the time it takes the water drop to drain the silicone film. This timescale is found to highly depend on how well water wets the solid, illustrating the interplay between intermolecular and hydrodynamic forces in the phenomenon. A phase diagram for the thin film stability is extracted based on waters equilibrium contact angle on the solid, which shows that we can either promote or inhibit de-wetting. As water comes in direct contact with the solid, it spreads and peels off the silicone film. We show the influence of viscosity, equilibrium contact angle and film height on the opening radius of the hole formed as the solid de-wets.

Melt focusing and CO2 extraction at mid-ocean ridges: simulations of reactive two-phase flow

NASA Astrophysics Data System (ADS)

Keller, T.; Katz, R. F.; Hirschmann, M. M.

2016-12-01

The deep CO2 cycle is the result of fluxes between near-surface and mantle reservoirs. Outgassing from mid-ocean ridges is one of the primary fluxes of CO2 from the asthenosphere into the ocean-atmosphere reservoir. Focusing of partial melt to the ridge axis crucially controls this flux. However, the role of volatiles, in particular CO2 and H2O, on melt transport processes beneath ridges remains poorly understood. We investigate this transport using numerical simulations of two-phase, multi-component magma/mantle dynamics. The phases are solid mantle and liquid magma; the components are dunite, MORB, hydrated basalt, and carbonated basalt. These effective components capture accepted features of mantle melting with volatiles. The fluid-dynamical model is McKenzie's formulation [1], while melting and reactive transport use the R_DMC method [2,3]. Our results indicate that volatiles cause channelized melt transport, which leads to significant variability in volume and composition of focused melt. The volatile-induced expansion of the melting regime at depth, however, has no influence on melt focusing; distal volatile-rich melts are not focused to the axis. Up to 50% of these melts are instead emplaced along the oceanic LAB. There, crystallization of accumulated melt leads to enrichment of CO2 and H2O in the deep lithosphere, which has implications for LAB rheology and volatile recycling by subduction. Results from a suite of simulations, constrained by catalogued observational data [4,5,6] enable predictions of global MOR CO2 output. By combining observational constraints with self-consistent numerical simulations we obtain a range of CO2 output from the global ridge system of 28-110 Mt CO2/yr, corresponding to mean CO2 contents of 50-200 ppm in the mantle. REFERENCES[1] McKenzie (1984), doi:10.1093/petrology/25.3.713.[2] Rudge, Bercovici & Spiegelman (2011), doi:10.1111/j.1365-246X.2010.04870.x.[3] Keller & Katz (2016), doi:10.1093/petrology/egw030.[4] Dalton, Langmuir & Gale (2014), doi:10.1126/science.1249466.[5] Gale, Langmuir & Dalton (2014), doi:10.1093/petrology/egu017.[6] White et al. (2001), doi:10.1093/petrology/42.6.1171. Fig: Simulation results of MOR magma/mantle dynamics with H2O and CO2, showing Darcy flux magnitude for half-spreading rates of 1 and 5 cm/yr.