Pure H2O Research Articles

Mass Spectrometric Characterization of Oligomers in Pseudomonas aeruginosa Azurin Solutions

We have employed laser-induced liquid bead ion desorption mass spectroscopy (LILBID MS) to study the solution behavior of Pseudomonas aeruginosa azurin as well as two mutants and corresponding Re-labeled derivatives containing a Re(CO)(3)(4,7-dimethyl-1,10-phenanthroline)(+) chromophore appended to a surface histidine. LILBID spectra show broad oligomer distributions whose particular patterns depend on the solution composition (pure H(2)O, 20-30 mM NaCl, 20 and 50 mM NaP(i) or NH(4)P(i) at pH = 7). The distribution maximum shifts to smaller oligomers upon decreasing the azurin concentration and increasing the buffer concentration. Oligomerization is less extensive for native azurin than its mutants. The oligomerization propensities of unlabeled and Re-labeled proteins are generally comparable, and only Re126 shows some preference for the dimer that persists even in highly diluted solutions. Peak shifts to higher masses and broadening in 20-50 mM NaP(i) confirm strong azurin association with buffer ions and solvation. We have found that LILBID MS reveals the solution behavior of weakly bound nonspecific protein oligomers, clearly distinguishing individual components of the oligomer distribution. Independently, average data on oligomerization and the dependence on solution composition were obtained by time-resolved anisotropy of the Re-label photoluminescence that confirmed relatively long rotation correlation times, 6-30 ns, depending on Re-azurin and solution composition. Labeling proteins with Re-chromophores that have long-lived phosphorescence extends the time scale of anisotropy measurements to hundreds of nanoseconds, thereby opening the way for investigations of large oligomers with long rotation times.

Spectroscopic Properties and Hydration of the Cm(III) Aqua Ion from 10 to 85 °C

The optical absorption, fluorescence excitation, and emission spectra of the Cm(III) aqua ion in 0.001 M perchloric acid were studied in pure H(2)O, pure D(2)O, and in mixtures of H(2)O-D(2)O at temperatures from 10 to 85 °C. The quantum yield of the fluorescence of the Cm(III) aqua ion in pure H(2)O and D(2)O was also measured in this temperature range and the radiative decay rate constant was obtained from these data. The results indicate that, from 10 to 85 °C, the effect of temperature on the absorption, excitation, and emission spectra is very small. By correcting the observed decay rate constant for the radiative rate constant, a set of correlations between the observed fluorescence decay rate constant and the hydration number of Cm(3+) in H(2)O at temperatures from 10 to 85 °C was developed. A weak temperature dependence was observed for the nonradiative decay rate constant for the (6)D'(7/2)-(8)S'(7/2) transition and described by the Arrhenius equation. The activation energy of the nonradiative decay was measured to be 0.9 kJ mol(-1), approximately matching the energy gap between the first and the second (A(1) and A(2)) levels of the metastable (6)D'(7/2) multiplet of the Cm(III) aqua ion. On the basis of these observations, it is postulated that the slight increase in the observed fluorescence decay rate constant as the temperature increases from 10 to 85 °C is due to the effect of thermal population of the A(2) level.

Kinetics and mechanism of the oxidation of hydroxylamine by a {Mn3O4}4+ core in aqueous acidic media

In this work we report the kinetics of oxidation of hydroxylamine by a trinuclear Mn(IV) oxidant, [Mn(3)(μ-O)(4)(phen)(4)(H(2)O)(2)](4+) (1, phen = 1,10-phenanthroline), in aqueous solution over a pH range 2.0-4.0. The trinuclear Mn(IV) species (1) deprotonates in aqueous solution at physiological pH: 1 ⇌ 2 + H(+); pK(1) = 4.00 (± 0.15) at 25.0 °C, I = 1.0 (M) NaNO(3). Both 1 and 2 are reactive oxidants reacting with the conjugate acid of hydroxylamine, viz. NH(3)OH(+) where the deprotonated oxidant 2 reacts faster. This finding is in contrast to a common observation and belief that protonated oxidants react quicker than their deprotonated analogues. Mn(IV)(3) to Mn(II) transition in the present reaction proceeds through the intervention of a spectrally detected mixed-valent Mn(III)Mn(IV) dimer that quickly collapses to Mn(II). The rate of the reaction was found to be lowered in D(2)O-enriched media in comparison to that in pure H(2)O media. An initial one electron one proton transfer to Mn(IV)(3) (electroprotic; 1e, 1H(+)) could be mechanistically conceived as the rate step. We also demonstrate by means of high level DFT studies that, among the two sets of Mn(IV) atoms in the trinuclear oxidant, the unique one that is coordinated with two phen ligands and two oxo-bridges is reduced to Mn(III) at the rate step. This is explained based on energetic and spin density calculations. Moreover, this result agrees with the charge distribution on the Mn atoms of the trinuclear complex.

Photo-desorbed species produced by the UV/EUV irradiation of an H2O:CO2:NH3 ice mixture

An H2O:CO2:NH3=1:1:1 ice mixture, used as a model mixture for cometary and interstellar ices, was irradiated with ultraviolet (UV)/extreme ultraviolet (EUV) photons in the broad 4–20eV (62–310nm) energy range at 16K. The desorbed species were detected in situ by mass spectrometry during photo-irradiation, and a quartz microbalance was used as a substrate to measure the mass of material remaining on the surface. The total mass desorption for this H2O:CO2:NH3=1:1:1 ice mixture at 16K was measured to be 1.8×10−18μgphoton−1, which is comparable to the 1.5×10−18μgphoton−1 measured for pure H2O ice irradiated under the same conditions. The main desorbed species produced during the photolysis of the ices were H2, NH2•, OH•, CO, and O2, along with the starting components H2O, NH3, and CO2. We also tentatively assigned minor mass peaks to larger species such as OCN•/OCN−, HNCO, CH4, H2CO, CH3OH, and HCOOH. This result supports the scenario in which complex organic molecules can be formed in cometary and/or astrophysical ices and desorbed to the gas phase, and helps to better understand the photochemical processes occurring at the surface of Solar System icy bodies such as comets, as well as in cold astrophysical environments such as star-forming regions and protostars.

In search of water vapor on Jupiter: Laboratory measurements of the microwave properties of water vapor under simulated jovian conditions

Detection and measurement of atmospheric water vapor in the deep jovian atmosphere using microwave radiometry has been discussed extensively by Janssen et al. (Janssen, M.A., Hofstadter, M.D., Gulkis, S., Ingersoll, A.P., Allison, M., Bolton, S.J., Levin, S.M., Kamp, L.W. [2005]. Icarus 173 (2), 447–453.) and de Pater et al. (de Pater, I., Deboer, D., Marley, M., Freedman, R., Young, R. [2005]. Icarus 173 (2), 425–447). The NASA Juno mission will include a six-channel microwave radiometer system (MWR) operating in the 1.3–50cm wavelength range in order to retrieve water vapor abundances from the microwave signature of Jupiter (see, e.g., Matousek, S. [2005]. The Juno new frontiers mission. Tech. Rep. IAC-05-A3.2.A.04, California Institute of Technology). In order to accurately interpret data from such observations, nearly 2000 laboratory measurements of the microwave opacity of H2O vapor in a H2/He atmosphere have been conducted in the 5–21cm wavelength range (1.4–6GHz) at pressures from 30 mbars to 101 bars and at temperatures from 330 to 525K. The mole fraction of H2O (at maximum pressure) ranged from 0.19% to 3.6% with some additional measurements of pure H2O. These results have enabled development of the first model for the opacity of gaseous H2O in a H2/He atmosphere under jovian conditions developed from actual laboratory data. The new model is based on a terrestrial model of Rosenkranz et al. (Rosenkranz, P.W. [1998]. Radio Science 33, 919–928), with substantial modifications to reflect the effects of jovian conditions. The new model for water vapor opacity dramatically outperforms previous models and will provide reliable results for temperatures from 300 to 525K, at pressures up to 100 bars and at frequencies up to 6GHz. These results will significantly reduce the uncertainties in the retrieval of jovian atmospheric water vapor abundances from the microwave radiometric measurements from the upcoming NASA Juno mission, as well as provide a clearer understanding of the role deep atmospheric water vapor may play in the decimeter-wavelength spectrum of Saturn.

Speciation and mixing behavior of silica-saturated aqueous fluid at high temperature and pressure

The effect of dissolved silica on the PVT properties of H2O and structure of silica-saturated aqueous fluids in equilibrium with quartz in the SiO2-H2O system has been determined in situ with the materials at temperature (up to 800 °C) and pressure (up to 1350 MPa) in a constant-volume hydrothermal diamond anvil cell. Pressure was measured with the Raman shift of 13C synthetic diamond and was also calculated from the PVT properties of pure H2O. The two sets of pressures thus obtained differ by ≤50 MPa at T < 500 °C. At higher temperatures (and pressures), the pressure difference increases and reaches about 350 MPa at 800 °C. The structure of the silica-saturated aqueous fluid was probed with microRaman and microFTIR methods. Coexisting molecular H2O and OH-groups, bonded to Si4+, exist above ~400 °C and ~0.4 GPa with their abundance-ratio, OH/H2O°, positively correlated with temperature. Hydrogen bonding diminishes with temperature and cannot be detected in the silica-saturated aqueous fluid above ~400 °C and ~0.4 GPa. This behavior resembles that of pure H2O under similar temperature and pressure conditions. Speciation of dissolved silica in the fluid at 400 °C/760 MPa, and above, comprises Qo and Q1 species, whereas at lower temperature and pressure only Qo species were detected. The Q1/Qo abundance ratio is positively correlated with temperature (and silica content). An excess volume of mixing, V H2Oexcess, derived from a comparison of EOS of pure H2O and those of silicate-saturated H2O, is related to the Q1/Qo abundance ratio in silicate-saturated fluid, XQ1/XQo. The V H2Oexcess = M H2O(1/ d m −1H2O/0.88), V H2Oexcess ~ 0 when XQ1/XQo approaches 0.

Thermodynamic data and modeling of the water and ammonia-water phase diagrams up to 2.2 GPa for planetary geophysics

We present new experimental data on the liquidus of ice polymorphs in the H(2)O-NH(3) system under pressure, and use all available data to develop a new thermodynamic model predicting the phase behavior in this system in the ranges (0-2.2 GPa; 175-360 K; 0-33 wt % NH(3)). Liquidus data have been obtained with a cryogenic optical sapphire-anvil cell coupled to a Raman spectrometer. We improve upon pre-existing thermodynamic formulations for the specific volumes and heat capacities of the solid and liquid phase in the pure H(2)O phase diagram to ensure applicability of the model in the low-temperature metastable domain down to 175 K. We compute the phase equilibria in the pure H(2)O system with this new model. Then we develop a pressure-temperature dependent activity model to describe the effect of ammonia on phase transitions. We show that aqueous ammonia solutions behave as regular solutions at low pressures, and as close-to-ideal solutions at pressure above 600 MPa. The computation of phase equilibria in the H(2)O-NH(3) system shows that ice III cannot exist at concentrations above 5-10 wt % NH(3) (depending on pressure), and ice V is not expected to form above 25%-27% NH(3). We eventually address the applications of this new model for thermal and evolution models of icy satellites.

Mechanism for the abiotic synthesis of uracil via UV-induced oxidation of pyrimidine in pure H2O ices under astrophysical conditions

The UV photoirradiation of pyrimidine in pure H(2)O ices has been explored using second-order Moller-Plesset perturbation theory and density functional theory methods, and compared with experimental results. Mechanisms studied include those starting with neutral pyrimidine or cationic pyrimidine radicals, and reacting with OH radical. The ab initio calculations reveal that the formation of some key species, including the nucleobase uracil, is energetically favored over others. The presence of one or several water molecules is necessary in order to abstract a proton which leads to the final products. Formation of many of the photoproducts in UV-irradiated H(2)O:pyrimidine=20:1 ice mixtures was established in a previous experimental study. Among all the products, uracil is predicted by quantum chemical calculations to be the most favored, and has been identified in experimental samples by two independent chromatography techniques. The results of the present study strongly support the scenario in which prebiotic molecules, such as the nucleobase uracil, can be formed under abiotic processes in astrophysically relevant environments, namely in condensed phase on the surface of icy, cold grains before being delivered to the telluric planets, like Earth.

Segregating gas from melt: an experimental study of the Ostwald ripening of vapor bubbles in magmas

Diffusive coarsening (Ostwald ripening) of H2O and H2O-CO2 bubbles in rhyolite and basaltic andesite melts was studied with elevated temperature–pressure experiments to investigate the rates and time spans over which vapor bubbles may enlarge and attain sufficient buoyancy to segregate in magmatic systems. Bubble growth and segregation are also considered in terms of classical steady-state and transient (non-steady-state) ripening theory. Experimental results are consistent with diffusive coarsening as the dominant mechanism of bubble growth. Ripening is faster in experiments saturated with pure H2O than in those with a CO2-rich mixed vapor probably due to faster diffusion of H2O than CO2 through the melt. None of the experimental series followed the time1/3 increase in mean bubble radius and time−1 decrease in bubble number density predicted by classical steady-state ripening theory. Instead, products are interpreted as resulting from transient regime ripening. Application of transient regime theory suggests that bubbly magmas may require from days to 100 years to reach steady-state ripening conditions. Experimental results, as well as theory for steady-state ripening of bubbles that are immobile or undergoing buoyant ascent, indicate that diffusive coarsening efficiently eliminates micron-sized bubbles and would produce mm-sized bubbles in 102–104 years in crustal magma bodies. Once bubbles attain mm-sizes, their calculated ascent rates are sufficient that they could transit multiple kilometers over hundreds to thousands of years through mafic and silicic melt, respectively. These results show that diffusive coarsening can facilitate transfer of volatiles through, and from, magmatic systems by creating bubbles sufficiently large for rapid ascent.

Thermodynamic model for mineral solubility in aqueous fluids: theory, calibration and application to model fluid‐flow systems

Geofluids(2010)10, 20–40AbstractWe present a thermodynamic model for mineral dissolution in aqueous fluids at elevated temperatures and pressures, based on intrinsic thermal properties and variations of volumetric properties of the aqueous solvent. The standard thermodynamic properties of mineral dissolution into aqueous fluid consist of two contributions: one from the energy of transformation from the solid to the hydrated‐species state and the other from the compression of solvent molecules during the formation of a hydration shell. The latter contribution has the dimension of the generalized Krichevskii parameter. This approach describes the energetics of solvation more accurately than does the Born electrostatic theory and can be extended beyond the limits of experimental measurements of the dielectric constant of H2O. The new model has been calibrated by experimental solubilities of quartz, corundum, rutile, calcite, apatite, fluorite and portlandite in pure H2O at temperatures up to 1100°C and pressures up to 20 kbar. All minerals show a steady increase in solubility along constant geothermal gradients or water isochores. By contrast, isobaric solubilities initially increase with rising temperature but then decline above 200–400°C. This retrograde behavior is caused by variations in the isobaric expansivity of the aqueous solvent, which approaches infinity at its critical point. Oxide minerals predominantly dissolve to neutral species; so, their dissolution energetics involve a relatively small contribution from the solvent volumetric properties and their retrograde solubilities are restricted to a relatively narrow window of temperature and pressure near the critical point of water. By contrast, Ca‐bearing minerals dissolve to a variety of charged species; so, the energetics of their dissolution reactions involve a comparatively large contribution from volume changes of the aqueous solvent and their isobaric retrograde solubility spans nearly all metamorphic and magmatic conditions. These features correlate with and can be predicted from the standard partial molar volumes of aqueous species.The thermodynamic model can be used over much wider range of settings for terrestrial fluid–rock interaction than has previously been possible. To illustrate, it is integrated with transport theory to show quantitatively that integrated fluid fluxes characteristic of crustal shear zones are capable of precipitating quartz or calcite veins from low‐ and medium‐grade metamorphic conditions, at a geothermal gradient of 20°C km−1. For subduction zones, modeled by a geotherm of 7°C km−1, the required fluid fluxes are one to two orders of magnitude lower and predict enhanced efficiency of mass transfer and metasomatic precipitation in comparison with orogenic settings. The new model thus can be applied to shallow hydrothermal, metamorphic, magmatic and subduction fluids, and for retrieval of dependent thermodynamic properties for mass transfer or geodynamic modeling.

Role of saline fluids in deep‐crustal and upper‐mantle metasomatism: insights from experimental studies

Geofluids (2010) 10, 58–72AbstractChloride‐rich brines are increasingly recognized as playing an important role in high pressure and temperature metamorphic and magmatic systems. The origins of these saline multicomponent fluids are debated, but experimental evidence suggests that regardless of their origin they must be important agents of rock alteration and mass transfer wherever they occur. Studies of the solubility of quartz in H2O, CO2–H2O and salt–H2O solutions provide a framework for understanding the role of brines in the deep crust and upper mantle. While quartz solubility in the system SiO2–H2O–NaCl–CO2 is maximal at a given high pressure and temperature if the solvent is pure H2O, the decline in quartz solubility with NaCl content (salting‐out) is less severe than in CO2–H2O fluids at comparable H2O activities. Moreover, at lower pressures, quartz solubility initially salts in at low salt contents, before reaching a maximum and then declining. The behavior of quartz solubility in salt–H2O solutions has not yet been fully explained and is the subject of active debate. Experimental investigations of the solubility of some other rock‐forming oxides and silicates show enhancements due to NaCl addition. As illustrated by the well‐studied CaO–Al2O3–SiO2–NaCl–H2O system, enhancements initially increase to maxima, and then decline. This behavior can be explained by formation of a range of hydrated aqueous complexes and clusters with specific NaCl:H2O stoichiometries. In contrast, solubilities of calcium salts, including calcite, fluorite, fluorapatite and anhydrite, rise monotonically with increasing NaCl, implying complexing to form anhydrous ionic solutes and/or ion pairs. The experimental studies offer new insights into fluid‐rock interaction in a range of settings, including carbonatite–fenite complexes, granulite‐facies metamorphism, porphyry ore deposits and aluminum‐silicate vein complexes in high‐grade metamorphic terranes.

Aqueous fluids at elevated pressure and temperature

AbstractThe general major component composition of aqueous fluids at elevated pressure and temperature conditions can be represented by H2O, different non‐polar gases like CO2 and different dissolved metal halides like NaCl or CaCl2. At high pressure, the mutual solubility of H2O and silicate melts increases and also silicates may form essential components of aqueous fluids. Given the huge range of P–T–x regimes in crust and mantle, aqueous fluids at elevated pressure and temperature are highly variable in composition and exhibit specific physicochemical properties. This paper reviews principal phase relations in one‐ and two‐component fluid systems, phase relations and properties of binary and ternary fluid systems, properties of pure H2O at elevated P–T conditions, and aqueous fluids in H2O–silicate systems at high pressure and temperature. At metamorphic conditions, even the physicochemical properties of pure water substantially differ from those at ambient conditions. Under typical mid‐ to lower‐crustal metamorphic conditions, the density of pure H2O is , the ion product Kw = 10−7.5 to approximately 10−12.5, the dielectric constant ε = 8–25, and the viscosity η = 0.0001–0.0002 Pa sec compared to , Kw = 10−14, ε = 78 and η = 0.001 Pa sec at ambient conditions. Adding dissolved metal halides and non‐polar gases to H2O significantly enlarges the pressure–temperature range, where different aqueous fluids may co‐exist and leads to potential two‐phase fluid conditions under must mid‐ to lower‐crustal P–T conditions. As a result of the increased mutual solubility between aqueous fluids and silicate melts at high pressure, the differences between fluid and melt vanishes and the distinction between fluid and melt becomes obsolete. Both are completely miscible at pressures above the respective critical curve giving rise to so‐called supercritical fluids. These supercritical fluids combine comparably low viscosity with high solute contents and are very effective metasomatising agents within the mantle wedge above subduction zones.

Effects of Chemical Treatment on the Luminescence of ZnO

The effects of chemical treatment on the luminescence of ZnO were investigated by cathodoluminescence. For this purpose, ZnO ceramics and O- and Zn-terminated faces of ZnO single crystals were studied. The samples were dipped in KOH and HCl solutions as well as pure H2O for 3 min. H2O and HCl treatments of ZnO ceramics can increase or decrease the initial ultraviolet (UV) intensity depending on the location examined, and induce an increase of the UV intensity under e-beam irradiation. HCl treatment of the Zn-face of ZnO single crystals slightly affects the surface morphology and the luminescence. HCl treatment of the O-face etches the surface to hexagonal pyramidal features. In addition, the initial UV intensity is always lower for the HCl-treated than for the untreated O-face, while the UV intensity increases at the beginning of e-beam irradiation. These results suggest that the UV intensity is influenced by the surface and bulk reactions of H+ with ZnO.

Lipid- and water-soluble bilirubins

Novel bilirubin analogs with two nonionic, water-solubilizing polyethyleneglycol (PEG) β-substituents of varying chain length on the lactam ring of each dipyrrinone were synthesized. In contrast to bilirubin, which is insoluble in CH3OH and in H2O at pH 7 but somewhat soluble in CHCl3 (~1 mM), the PEGylated rubins are soluble in all three solvents, with H2O solubility increasing with increasing number of ethyleneglycol units in the PEG chain(s). Vapor pressure osmometry indicates that, like bilirubin, they are monomeric in CHCl3 and in CH3OH. Nuclear magnetic resonance (NMR) studies indicate that their most stable structure in these solvents and in H2O has the 4Z,15Z configuration that is bent into a ridge-tile shape with the pigment’s dipyrrinones engaged in intramolecular hydrogen bonding to the propionic acid carboxyl groups. Aqueous pK a values for the intramolecularly hydrogen-bonded carboxyl groups of these compounds, determined by vacuum-assisted multiplexed capillary electrophoresis in H2O–CH3OH mixtures followed by Yesuda-Shedlovsky extrapolations to pure H2O, were found to be 4.9, as previously determined by NMR titrations for mesobilirubin-XIIIα.

Photochemistry of carbon monoxide and methanol in water and nitric acid hydrate ices: A NEXAFS study

Soft X-ray induced chemistry of H(2)O, CO and CH(3)OH and the effects of the water and nitric acid hydrate (HNO(3).1.65H(2)O) matrix on the photochemistry of CO and CH(3)OH have been investigated using NEXAFS spectroscopy. For pure H(2)O, CO and CH(3)OH ices, we show that the destruction rates are strongly limited by back reactions, leading to strikingly high survival rates of these molecules upon the harsh irradiation conditions to which they are submitted. We also evidence the interplay between the photochemical reactions of CO and CH(3)OH and those of the matrix. The OH and O radicals released by the photolysis of H(2)O and HNO(3) react with the CO and CH(3)OH and their fragments, considerably reducing the survival rates compared to pure CO and pure CH(3)OH ices, especially in presence of nitric acid, and dramatically enhancing the formation of CO(2) at the expense of CO. Because NEXAFS spectroscopy allows identifying which reactions are important among those possible, it emerges a simple picture of the photochemical routes of CO and CH(3)OH in the H(2)O and HNO(3)/H(2)O environments.

Low temperature improvement method on characteristics of Ba(Zr0.1Ti0.9)O3 thin films deposited on indium tin oxide/glass substrates

To improve the electrical properties of as-deposited BZ1T9 ferroelectric thin films, the supercritical carbon dioxide fluid (SCF) process were used by a low temperature treatment. In this study, the BZ1T9 ferroelectric thin films were post-treated by SCF process which mixed with propyl alcohol and pure H2O. After SCF process treatment, the remnant polarization increased in hysteresis curves, and the passivation of oxygen vacancy and defect in leakage current density curves were found. Additionally, the improvement qualities of as-deposited BZ1T9 thin films after SCF process treatment were carried out XPS, C–V, and J–E measurements.

Photocatalytic Splitting of Water Over a Novel Visible-Light-Response Photocatalyst Nd2InTaO7

A new visible-light-response photocatalyst Nd2InTaO7 with pyrochlore-type structure crystallized in a cubic system with the space group Fd3m was synthesized by a solid-state reaction method. The H2 evolution was obtained from Pt/CH3OH/H2O solution and pure H2O, and O2 evolution was generated from an aqueous AgNO3 solution under visible light irradiation (λ > 400 nm). The high photocatalytic performance of Nd2InTaO7 supported the existing view that the photocatalytic activity correlated with the lattice distortion.

A melt and fluid inclusion assemblage in beryl from pegmatite in the Orlovka amazonite granite, East Transbaikalia, Russia: implications for pegmatite-forming melt systems

Beryl crystals from the stockscheider pegmatite in the apical portion of the Li-F granite of the Orlovka Massif in the Khangilay complex, a tantalum deposit, contain an assemblage of melt and fluid inclusions containing two different and mutually immiscible silicate melts, plus an aqueous CO2-rich supercritical fluid. Pure H2O and CO2 inclusions are subordinate. Using the terminology of Thomas R, Webster JD, Heinrich W. Contrib Mineral Petrol 139:394–401 (2000) the melt inclusions can be classified as (i) water-poor type-A and (ii) water-rich type-B inclusions. Generally the primary trapped melt droplets have crystallized to several different mineral phases plus a vapor bubble. However, type-B melt inclusions which are not crystallized also occur, and at room temperature they contain four different phases: a silicate glass, a water-rich solution, and liquid and gaseous CO2. The primary fluid inclusions represent an aqueous CO2-rich supercritical fluid which contained elemental sulfur. Such fluids are extremely corrosive and reactive and were supersaturated with respect to Ta and Zn. From the phase compositions and relations we can show that the primary mineral-forming, volatile-rich melt had an extremely low density and viscosity and that melt-melt-fluid immiscibility was characteristic during the crystallization of beryl. The coexistence of different primary inclusion types in single growth zones underlines the existence of at least three mutually immiscible phases in the melt in which the large beryl crystals formed. Moreover, we show that the inclusions do not represent an anomalous boundary layer.

A low-temperature method for improving the performance of sputter-deposited ZnO thin-film transistors with supercritical fluid

A low-temperature method, supercritical CO2 (SCCO2) fluid technology, is employed to improve the device properties of ZnO TFT at 150 °C. In this work, the undoped ZnO films were deposited by sputter at room temperature and treated by SCCO2 fluid which is mixed with 5 ml pure H2O. After SCCO2 treatment, the on/off current ratios and threshold voltage of the device were improved significantly. From x-ray photoelectron spectroscopy analyses, the enhancements were attributed to the stronger Zn–O bonds, the hydrogen-related donors, and the reduction in dangling bonds at the grain boundary by OH passivation.

A generic feasibility study of batch reactive distillation in hybrid configurations

AbstractA new graphical feasibility method is developed to investigate batch reactive distillation processes in middle vessel column. The suggested methodology can deal with fully reactive, nonreactive, and complex column configuration. A new formulation is suggested to describe the composition profiles in the reactive sections. Its application has made possible to develop a generic feasibility methodology containing the same model equations independently of the presence or absence of reaction. By combining the reactive and nonreactive models, not only the fully reactive and fully nonreactive but also hybrid configurations can be studied. Feasibility criteria related to the hybrid configurations are also presented. Application of the new methodology is demonstrated on the production of ethyl acetate in batch reactive distillation. Five configurations are found feasible; pure EtOAc is produced as distillate, and pure H2O is produced at the bottom. In each case, continuous feeding of AcOH is necessary. © 2009 American Institute of Chemical Engineers AIChE J, 2009