Low Mole Research Articles

Melt inclusion CO2 contents, pressures of olivine crystallization, and the problem of shrinkage bubbles

The H2O and CO2 contents of melt inclusions can potentially be used to infer pressures of crystallization and inclusion entrapment because the solubility of mixed H2O-CO2 vapor has been determined experimentally for a wide range of melt compositions. However, melt inclusions commonly develop a shrinkage bubble during post-entrapment cooling and crystallization because these processes cause a pressure drop in the inclusion. This pressure drop causes a vapor bubble to nucleate, leading to exsolution of low-solubility CO2 from the trapped melt. To investigate the loss of CO2 into such bubbles, we experimentally heated large, naturally glassy melt inclusions in olivine (Fo contents of 88.1 ± 0.2) from a Mauna Loa picrite to rehomogenize the inclusions. Rapid heating to 1420 °C using a hightemperature heating stage dissolved the shrinkage bubbles into the melt. CO2 contents measured by FTIR spectroscopy and recalculated for melt in equilibrium with the olivine host are 224-505 ppm (n = 11) for heated inclusions, much higher than the CO2 contents of naturally quenched inclusions from the same sample (38-158 ppm; n = 8). Pressures of inclusion entrapment calculated from the H2O and CO2 data for the heated inclusions range from 0.5 to 1.1 kbar, indicating that Mg-rich olivine crystallized at very shallow depths beneath the surface of Mauna Loa. Our results indicate that 40-90% (average 75%) of the original CO2 dissolved in the melt at the time of inclusion entrapment can be lost to the shrinkage bubble during post-entrapment cooling. We show that the computational method of Riker (2005), which predicts the pre-eruption shrinkage bubble size as a function of the difference between trapping temperature and pre-eruption temperature, successfully reproduces our experimental results. Our results demonstrate that the mass of CO2 contained in shrinkage bubbles must be considered to accurately infer original pressures of crystallization for melt inclusions. However, the effect is expected to be smaller for more H2O-rich melt inclusions than those studied here because the vapor bubble in such inclusions will have lower mole fractions of CO2 than the low-H2O inclusions in our study.

Clinical and biochemical tear lipid parameters in contact lens wearers.

Alterations in tear film lipids may be important in modulating discomfort during contact lens wear. This study investigates associations between clinical and biological components of the lipid layer and seeks to determine the effect of lipid supplementation on contact lens wear comfort. Participants were grouped into symptomatic (n = 10) and asymptomatic (n = 10) contact lens wearers according to the Contact Lens Dry Eye Questionnaire. After 6 hours of lens wear, noninvasive surface drying time (NISDT) and the lipid layer grade were assessed using a Tearscope. Basal tears were collected using a microcapillary tube and assayed for concentration and activity of the secretory phospholipase A2 enzyme and concentration of the lipid aldehyde malondialdehyde. Mass spectrometry was used to characterize the tear lipidome. In the second phase, a liposomal spray (Tears Again, BioRevive) or a saline spray was sprayed over the upper eyelids of each subject during their down gaze and during lens wear. Noninvasive surface drying time and ocular comfort were obtained soon after spraying and again at 2 and 6 hours after the initial spray. Statistical tests included the Student t test, repeated-measures analysis of variance, and the Pearson correlation test where appropriate. Noninvasive surface drying time was lower (p = 0.01) in symptomatic (4.5 ± 0.6 seconds) than in asymptomatic (9.9 ± 3.1 seconds) contact lens wearers. The mole percentage of wax esters in the total lipidome increased with NISDT (R = 0.70, p = 0.01). Secretory phospholipase A2 enzyme activity in tears was associated with higher levels of malondialdehyde (R = 0.65, p = 0.01) and shorter NISDT (R = 0.84, p = 0.001). Noninvasive surface drying time reduced over the time course for the saline spray (p = 0.01) but did not reduce until the 6-hour time point with the liposomal spray. With liposomal spray, NISDT was higher (p = 0.03) immediately after instillation compared with 6 hours later (9.5 ± 1.9 vs. 5.2 ± 2.1 seconds). A longer NISDT was associated with improved ocular comfort for those using the liposomal spray (R = 0.25, p = 0.005) but not with saline. Degraded lipids and a lower mole percentage of wax esters in the tear film may be associated with a lower NISDT. Lipid supplements may improve ocular comfort during lens wear by increasing NISDT.

Modification of the activated sludge model for chemical dosage

Full-scale experiments have been carried out to adapt the activated sludge model ASM2d to include the influence of metal dosage (Fe3+ and Al3+) for phosphorus removal. Phosphorus removal rates, nitrification rates, as well as pH and sludge settling performance, were evaluated as functions of the metal dosages. Furthermore, models relating certain parameters to the dosage of chemicals have been derived. Corresponding parameters in the ASM2d and the secondary settler models, included in the Benchmark Simulation Model No 1 (BSM1), have been modified to take the metal influence into consideration. Based on the effluent limits and penalty policy of China, an equivalent evaluation method was derived for the total cost assessment. A large number of 300-day steady-state and 14-day open-loop dynamic simulations were performed to demonstrate the difference in behavior between the original and the modified BSM1. The results show that 1) both in low and high mole concentrations, Fe3+ addition results in a higher phosphorus removal rate than Al3+; 2) the sludge settling velocity will increase due to the metal addition; 3) the respiration rate of the activated sludge is decreased more by the dosage of Al3+ than Fe3+; 4) the inhibition of Al3+ on the nitrification rate is stronger than that of Fe3+; 5) the total operating cost will reach the minimum point for smaller dosages of Fe3+, but always increase with Al3+ addition.

Study of Molecular Interactions in Ternary Mixtures of Quinoline with o-cresol, m-cresol and p-cresol in Methanol at T= 303.15, 308.15, 313.15, and 318.15 K

Aims: To evaluate the thermodynamical parameters and their excess functions to find the molecular interactions between unlike molecules in ternary liquid mixtures. Study Design: Ultrasonic velocities, densities and viscosities have been measured for the ternary mixtures of quinoline with cresols in methanol at different temperatures (303.15, 308.15, 313.15 and 318.15K) over the entire range of mole fraction. These measurements are used to evaluate thermodynamical parameters like adiabatic compressibility (β), free length (Lf), free volume (Vf), internal pressure (π), acoustic impedance (Z) and enthalpy (H) were calculated. From these values the excess properties such as excess adiabatic compressibility (β), excess free length (Lf), excess free volume (Vf), excess internal pressure (π), excess acoustic impedance Original Research Article International Research Journal of Pure & Applied Chemistry, 4(2): 213-226, 2014 214 (Z) and excess enthalpy (H) are calculated. Place and Duration of Study: Department of Physics and Department of Chemistry, V.R. Siddhartha Engineering College, Vijayawada, between April 2012 and June 2013. Methodology: The liquids were purified according to the standard procedures. Ultrasonic velocities of pure liquids and liquid mixtures were measured using ultrasonic interferometer, densities and viscosities were measured by using specific gravity bottle and Ostwald’s viscometer. Results: Excess adiabatic compressibility, excess free length and excess free volume exhibit negative values over the entire range of composition. In the first two systems the excess enthalpy values are found to be positive at lower mole fractions and negative for higher mole fraction range and at higher temperatures, whereas for system-3 these values are positive at all mole fractions and at temperatures 303.15, 308.15K and negative at temperatures 313.15 and 318.15K. Conclusion: These data are required in the development of models for energy

The Effect of Indium Mole Fraction on the Growth Behavior of Your In<sub><i>x</i></sub>Ga<sub>1-<i>x</i></sub>As Nanowires (NWs) Grown Using MOCVD

InxGa1-xAs NWs have been grown with various indium mole fractions (x) using MOCVD. The morphology of InxGa1-xAs NWs was observed using Field Emission-Scanning Electron Microscopy (FE-SEM) in order to study the growth behavior of the NWs. FE-SEM results show that the NWs growth mechanism has changed due to changing of indium mole fraction. At low indium mole fraction, the NWs grew via direct impinging mechanism which has produced NWs with relatively uniform diameter. By increasing the value of x the growth mechanism has transformed to the combination of direct impinging and diffusion of source atoms from the surface of substrate causing tapering of NWs. The degree of tapering increases with increasing value of indium mole fraction. InxGa1-xAs NW grown at x = 0.65 has the highest tapering factor, TF = 12.82, whereas NW grown at x = 0.41 has the lowest tapering factor, TF = 2.76.

Hydrogeochemical evolution of Ordovician limestone groundwater in Yanzhou, North China

AbstractMajor‐ion compositions of groundwater are employed in this study of the water–rock interactions and hydrogeochemical evolution within a carbonate aquifer system. The groundwater samples were collected from boreholes or underground tunnels in the Ordovician limestone of Yanzhou Coalfield where catastrophic groundwater inflows can be hazardous to mining and impact use of the groundwater as a water supply. The concentration of total dissolved solid (TDS) ranged from 961 to 3555 mg/l and indicates moderately to highly mineralized water. The main water‐type of the middle Ordovician limestone groundwater is Ca‐Mg‐SO4, with SO42‐ ranging from 537 to 2297 mg/l, and average values of Ca2+ and Mg2+ of 455.7 and 116.6 mg/l, respectively. The water samples were supersaturated with respect to calcite and dolomite and undersaturated or saturated with respect to gypsum. Along the general flow direction, deduced from increases of TDS and Cl‐, the main water–rock interactions that caused hydrogeochemical evolution of the groundwater within the aquifer were the dissolution of gypsum, the precipitation of calcite, the dissolution or precipitation of dolomite, and ion exchange. Ion exchange is the major cause for the lower mole concentration of Ca2+ than that of SO42‐. The groundwater level of Ordovician aquifer is much higher than that of C‐P coal‐bearing aquifers, so the potential flow direction is upward, and the pyrite in coal is not a possible source of sulfate; additional data on the stable sulfur and oxygen isotopic composition of the sulfate may be helpful to identify its origin. Although ion exchange probably accounts for the higher mole concentration of Na+ than that of Cl‐, the dissolution of aluminosilicate cannot be ruled out. The data evaluation methods and results of this study could be useful in other areas to understand flow paths in aquifers and to provide information needed to identify the origin of groundwater. Copyright © 2012 John Wiley & Sons, Ltd.

Effect of Sodium Dodecyl Sulfate on Volumetric Properties of Methanol Ethanol n-Propanol and iso-Propanol at (298.15 - 323.15)K

The critical micelle concentration (CMC) of Sodium dodecyl sulfate (SDS) in water was determined from the conductance and viscosity measurement. The estimated value of CMC was found to be 0.0085 mol.L-1 at 29°C. The concentration of SDS in pre-micellar and postmicellar region of 0.005M and 0.01M, respectively were used for the volumetric measurements of Methanol, Ethanol, n-Propanol and iso- Propanol with SDS solutions. Densities of ternary mixtures of Methanol, Ethanol, n-Propanol and iso-Propanol with 0.005M and 0.01M aqueous SDS have been studied over the entire range of composition at 298.15- 323.15K with an interval of 5K except Methanol. Methanol system was studied at 298.15-308.15K due to its low boiling point. The values of excess molar volumes, VE for all the systems are negative over the entire range of composition, showing minima at ~ 0.45 mole fraction of Methanol, ~ 0.4 mole fraction of Ethanol, ~ 0.25 mole fraction of n-Propanol and ~ 0.3 mole fraction of iso-Propanol. All the systems are showing minima at aqueous SDS rich region. The VE values for the n-Propanol + aqueous SDS and iso-Propanol + aqueous SDS mixtures are slightly sigmoid, being negative at lower mole fractions (x2) and positive at higher x2 of Propanols. The excess properties (VE) data have been fitted by the least square method to the four parameter Redlich-Kister equation and the values of the parameter aj have been reported.DOI: http://dx.doi.org/10.3329/dujs.v60i1.10351 Dhaka Univ. J. Sci. 60(1): 129-136 2012 (January)

Nonadditive Penetrable Mixtures in Nanopores: Surface-Induced Population Inversion

We investigate the surface-induced population inversion of the nonadditive penetrable mixtures which exhibits the fluid-fluid demixing transition of the bulk system due to the confinement effect. The result shows that the population inversions are strongly affected by the extra repulsion between unlike species, the mole fraction of species, the width of nanopores, and the nonadditive walls. The extra repulsion between unlike species in a confined system increases the contact density of both species at the wall and promotes the population inversion in nanopores. The population inversion is the typical shift first-order fluid-fluid demixing transition due to the confinement effect in nanopores. The population inversions are only observed in nanopores with finite widths. The population inversion line is shifted toward a higher fluid density with decreasing width of the nanopores and lies slightly in lower density compared with the coexistence curves of the bulk system. The nonadditive wall for the big particles leads to the population inversion in lower density compared with that of the nonadditive wall for the small particles. The population inversion line is terminated at a lower mole fraction.

Adsorption and separation of methane/hydrogen in octaphenylsilsesquioxane based covalently-linked organic-inorganic hybrid framework

The adsorption and separation of CH4/H2 in two covalently-linked organic-inorganic hybrid frameworks polyoctaphenylsilsesquioxane (JUC-Z1) were computationally studied using the Grand Canonical Monte Carlo (GCMC) simulations. The results show that JUC-Z1 with Linde type A (LTA) and polycubane (zeolite code ACO) net topologies can adsorb up to 20.32, 18.57 mmol/g of CH4 and 19.04, 17.89 mmol/g of H2 at 298 K and 10 MPa, respectively. For the adsorption of binary mixture, the selectivity of CH4 over H2 in LTA-JUC-Z1 decrease gradually with the increase of the pressure or the CH4 mole fraction of the mixture. As to ACO-JUC-Z1, the selectivity first increases at low pressure or CH4 mole fraction, and then begins to decrease with the further increase of the corresponding amount. Anyhow, the two materials both exhibit excellent adsorption and separation capacities of CH4/H2.

Preparation of CdTe nanostructures with different crystal structures and morphologies

CdTe nanorods and various branched nanostructures with different crystal structures were have successfully prepared via the catalyst-assisted vacuum thermal evaporation (CVTE) technique using various experimental parameters. SEM and XRD studies were carried out on the as-prepared CdTe nanostructures. The results show that the morphologies and crystal structures of the products were strongly influenced by the growth conditions and the mole ratios of Bi and CdTe. In the high mole ratio (0.08:1) of Bi and CdTe, CdTe branched nanostructures of CdTe were obtained, while nanorods of CdTe were formed at a lower mole ratio of 0.05:1. The crystal structure of products is either Zinc blende or a two-phase mixture of zinc blende and wurtzite. The content of the wurtzite phase were found to increase with increasing growth temperature. Our results also reveal that high growth temperature tends to form the wurtzite phase, and stacking faults may exist in materials grown in higher temperatures. These nanostructures grow following the vapor–liquid–solid (VLS) mechanism.

Methane hydrate phase stability with lower mole fractions of tetrahydrofuran (THF) and tert-butylamine ( t-BuNH 2)

A systematic study on methane hydrate formation and dissociation was carried out in presence of liquid hydrocarbon promoters namely tetrahydrofuran (THF) and tert-butylamine ( t-BuNH 2). Mixed hydrates with THF/t-BuNH 2 (mole fraction x = 0.05) were of sII symmetry. The hydrate formation/dissociation of mixed hydrates with x = 0.033 and 0.0056 were complex with co-existence of sII and sI structures. We observed the hydrate formation in two steps, hydrates in the first stage (∼ T = 295 K) were mostly with sII and in the second stage (∼ T = 275 K) were with sI structure, corroborating the literature. However, dissociation pattern of the hydrates formed in second stage significantly differ from pure methane hydrates and the above two liquid hydrocarbons show considerable promoter effect for sI hydrates.

Preparation of spherical silica particles in reverse micro emulsions using silicon tetrachloride as precursor

Silica powders with spherical shape have been prepared by precipitation reaction of silicon tetrachloride with de-ionized water in the micro emulsion system. Two kinds of micro emulsion systems were used. One was cyclohexane/polyoxyethylene nonyl phenyl ether (NP-5)/de-ionized water system, and the other was heptane e/NP-5/de-ionized water. Transmission electron microscope (TEM), thermo gravimetric analysis (TG), X-ray diffraction (XRD) patterns, infrared spectrum (IR) were employed to characterize the micro structure, shape, thermal properties, phase, and molecular structure of the obtained silica. The results show that silica featuring spherical shapes and uniform characteristics was yielded by the precipitation method using silicon tetrachloride with de-ionized water in the micro emulsion system. A decreased tendency for silica particles agglomeration could be achieved by using lower mole ratio of water and SiCl4, and the particle size was 5.74nm when mole ratio of water and SiCl4 was 4 in NP-5/cyclohexane/deionized water micro emulsion system. The silica prepared by these two systems was amorphous silica and thermally stable after 600°C treatment. The structures of silica prepared from the different micro emulsion systems were similar; organic molecules can be removed completely from the silica through 600°C treatment.

Measurement of CO2 Solubility in Ionic Liquids: [BMP][Tf2N] and [BMP][MeSO4] by Measuring Bubble-Point Pressure

This paper presents the bubble-point pressure data of CO2 in ionic liquids 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide ([BMP][Tf2N]) and 1-butyl-1-methylpyrrolidinium methylsulfate ([BMP][MeSO4]). In our research, the high-pressure phase behavior of carbon dioxide in [BMP][Tf2N] and [BMP][MeSO4] were observed at pressure up to about 100 MPa in a temperature range from (303.15 to 373.15) K in 10 K intervals by using a high-pressure variable-volume view cell. To investigate the effect of different anion on the solubility of CO2 in the [BMP] cation based ionic liquids, we compared three [BMP] cation based systems; [BMP][Tf2N] +, [BMP][TfO] +, and [BMP][MeSO4] + CO2. In all systems, at lower mole fraction of CO2 (below 0.3), the solubility is approximately the same, however above 0.3 mol fraction, the ration between pressure and CO2 mol fraction decreases sharply. Although these experiments have used the same cation, it would appear that the ratio decreases more sharply as the alkyl group...

Refractive Index of Liquid Mixtures: Theory and Experiment

An innovative approach is presented to interpret the refractive index of binary liquid mixtures. The concept of refractive index "before mixing" is introduced and shown to be given by the volume-fraction mixing rule of the pure-component refractive indices (Arago-Biot formula). The refractive index of thermodynamically ideal liquid mixtures is demonstrated to be given by the volume-fraction mixing rule of the pure-component squared refractive indices (Newton formula). This theoretical formulation entails a positive change of refractive index upon ideal mixing, which is interpreted in terms of dissimilar London dispersion forces centred in the dissimilar molecules making up the mixture. For real liquid mixtures, the refractive index of mixing and the excess refractive index are introduced in a thermodynamic manner. Examples of mixtures are cited for which excess refractive indices and excess molar volumes show all of the four possible sign combinations, a fact that jeopardises the finding of a general equation linking these two excess properties. Refractive indices of 69 mixtures of water with the amphiphile (R,S)-1-propoxypropan-2-ol are reported at five temperatures in the range 283-303 K. The ideal and real refractive properties of this binary system are discussed. Pear-shaped plots of excess refractive indices against excess molar volumes show that extreme positive values of excess refractive index occur at a substantially lower mole fraction of the amphiphile than extreme negative values of excess molar volume. Analysis of these plots provides insights into the mixing schemes that occur in different composition segments. A nearly linear variation is found when Balankina's ratios between excess and ideal values of refractive indices are plotted against ratios between excess and ideal values of molar volumes. It is concluded that, when coupled with volumetric properties, the new thermodynamic functions defined for the analysis of refractive indices of liquid mixtures give important complementary information on the mixing process over the whole composition range.

Investigation of temperature-swing adsorption of aromatic compounds in water using polyampholyte gels with hydrophilic nonionic groups

The adsorption and desorption behaviors of bisphenol-A in water have been studied using the temperature-responsive polyampholyte gels composed of sodium styrene sulfate (SSS), vinylbenzyl trimethylammonium chloride (VBTA), and N,N′-dimethylacrylamide (DMAA). The resultant behaviors of the SSS-VBTA-DMAA gels of three different monomer compositions are compared with those of the SSS-VBTA gel that can adsorb bisphenol-A at room temperature and desorb the pre-adsorbed bisphenol-A at higher temperature as in our previous report (Morisada et al., Adsorption 2008, 14, 621), to elucidate the effect of DMAA on the adsorption property of the polyampholyte gel. The adsorption isotherms, which were described by Henry's law, indicated that the adsorption amounts of bisphenol-A onto the SSS-VBTA-DMAA gels at 298 K are much larger than those at 353 K. At 298 K, the Henry's adsorption constant for the SSS-VBTA-DMAA gel with the lowest mole fraction of DMAA was larger than that for the SSS-VBTA gel, whereas a further increase in the DMAA mole fraction resulted in a decrease in the adsorption constant. Moreover, the temperature-swing adsorption experiments demonstrated that the SSS-VBTA-DMAA gel can repeatedly adsorb bisphenol-A at 298 K and desorb some of the pre-adsorbed bisphenol-A at 353 K, where the desorption amount of bisphenol-A is larger than that from the SSS-VBTA gel. The results obtained here show that the addition of DMAA to the SSS-VBTA gel slightly improves the performance of the gel as a temperature-responsive adsorbent. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Memory effect on semi-clathrate hydrate formation: A case study of tetragonal tetra- n-butyl ammonium bromide hydrate

Recrystallization in a tetragonal tetra- n-butyl ammonium bromide (hereafter, TBAB) semi-clathrate hydrate system has been investigated in TBAB aqueous solutions of two different concentrations (stoichiometric mole fraction for tetragonal TBAB hydrate formation and lower mole fraction than stoichiometric one) by use of optical microscopy. The recrystallization of TBAB hydrate has been observed under milder condition than that of the initial crystallization in both concentrations. In particular, solution of the lower concentration is easily recrystallized. This is the first observation of memory effect in a semi-clathrate hydrate system. In addition, the recrystallization occurs in the vicinity of the place where the last piece of initial crystal was dissociated. This implies that a small amount of residual structures remain in the dissociated water, but unfortunately they cannot be confirmed with Raman micro-spectroscopy.

Control of H‐ and J‐Type π Stacking by Peripheral Alkyl Chains and Self‐Sorting Phenomena in Perylene Bisimide Homo‐ and Heteroaggregates

The synthesis, self-assembly, and gelation ability of a series of organogelators based on perylene bisimide (PBI) dyes containing amide groups at imide positions are reported. The synergetic effect of intermolecular hydrogen bonding among the amide functionalities and pi-pi stacking between the PBI units directs the formation of the self-assembled structure in solution, which beyond a certain concentration results in gelation. Effects of different peripheral alkyl substituents on the self-assembly were studied by solvent- and temperature-dependent UV-visible and circular dichroism (CD) spectroscopy. PBI derivatives containing linear alkyl side chains in the periphery formed H-type pi stacks and red gels, whereas by introducing branched alkyl chains the formation of J-type pi stacks and green gels could be achieved. Sterically demanding substituents, in particular, the 2-ethylhexyl group completely suppressed the pi stacking. Coaggregation studies with H- and J-aggregating chromophores revealed the formation of solely H-type pi stacks containing both precursor molecules at a lower mole fraction of J-aggregating chromophore. Beyond a critical composition of the two chromophores, mixed H-aggregate and J-aggregate were formed simultaneously, which points to a self-sorting process. The versatility of the gelators is strongly dependent on the length and nature of the peripheral alkyl substituents. CD spectroscopic studies revealed a preferential helicity of the aggregates of PBI building blocks bearing chiral side chains. Even for achiral PBI derivatives, the utilization of chiral solvents such as (R)- or (S)-limonene was effective in preferential population of one-handed helical fibers. AFM studies revealed the formation of helical fibers from all the present PBI gelators, irrespective of the presence of chiral or achiral side chains. Furthermore, vortex flow was found to be effective in macroscopic orientation of the aggregates as evidenced from the origin of CD signals from aggregates of achiral PBI molecules.

(Surfactant + polymer) interaction parameter studied by (liquid + liquid) equilibrium data of quaternary aqueous solution containing surfactant, polymer, and salt

(Liquid + liquid) equilibrium (LLE) data of quaternary aqueous system containing polyoxyethylene (20) cetyl ether (with abbreviation name Brij 58, non-ionic surfactant), diammonium hydrogen phosphate, and poly ethylene glycol (PEG) with three molar masses { M W = (1000, 6000, and 35,000) g · mol −1} have been determined experimentally at T = 313.15 K. Furthermore, the Flory–Huggins theory with two electrostatic terms (Debye–Hückel and Pitzer–Debye–Hückel equations) have been used to calculate the phase behavior of the quaternary systems and (surfactant + polymer) interaction parameter as well as interaction parameters between other species. Temperature dependency of the parameters of the Flory–Huggins theory has been obtained. Also an effort have been done to show that addition of PEG as well as increasing the temperature can shift the binodal curves of the ternary aqueous system containing surfactant and salt to lower mole fraction of salt. Also the effect of polymer molar mass on the binodal diagram displacement has been discussed.

Thermodynamic and Raman spectroscopic studies on hydrogen+tetra- n-butyl ammonium fluoride semi-clathrate hydrates

Thermodynamic stability and hydrogen occupancy on the hydrogen+tetra- n-butyl ammonium fluoride semi-clathrate hydrate have been investigated by means of phase equilibrium (pressure–temperature) measurements and Raman spectroscopic analyses for two mole fractions, 0.018 and 0.034 (stoichiometric for the cubic structure) of tetra- n-butyl ammonium fluoride aqueous solutions. In the case of higher concentration (0.034), the stability boundary curve of hydrogen+tetra- n-butyl ammonium fluoride semi-clathrate hydrate locates at about 23 K higher temperature than that of hydrogen+tetrahydrofuran mixed gas hydrate. The storage capacity of hydrogen in the cubic structure for the hydrogen+tetra- n-butyl ammonium fluoride semi-clathrate hydrate is smaller than that of hydrogen+tetrahydrofuran mixed gas hydrate. In the case of hydrate prepared from the lower concentration (0.018) of aqueous solution, the Raman spectra and phase behavior reveal that the cubic structure of semi-clathrate hydrate is changed to a different one at about 9 MPa and 299.2 K. The new structure can entrap larger amount of hydrogen than the cubic one. The stability boundary curve of hydrogen+tetra- n-butyl ammonium fluoride semi-clathrate hydrate obtained in the aqueous solution of lower mole fraction (0.018) is shifted to slightly low-temperature or high-pressure side from that of higher mole fraction (0.034).

Transformation of Inorganic and Organic Arsenic byAlkaliphilus oremlandiisp. nov. Strain OhILAs

Alkaliphilus oremlandii sp. nov. strain OhILAs is a mesophilic, spore-forming, motile, low mole%GC gram positive. It was enriched from Ohio River sediments on a basal medium with 20 mM lactate and 5 mM arsenate and isolated through passage on medium with increased arsenic concentration (10 and 20 mM), tindalization, and serial dilution. The pH optimal for growth was 8.4 and 16S rRNA gene sequence analysis indicated it is most closely related to species in the genus Alkaliphilus (A. crotonoxidans 95%, A. auruminator 95%, A. metalliredigens, 94%). A strict anaerobe, it can ferment lactate via the acrylate pathway as well as fructose and glycerol. A. oremlandii also has respiratory capability, as it is able to use arsenate and thiosulfate as terminal electron acceptors with acetate, pyruvate, formate, lactate, fumarate, glycerol, or fructose as the electron donor. A respiratory arsenate reductase, which is constitutively expressed, has been identified through biochemical and Western blot analyses and confirmed by cloning and sequencing of the gene encoding the structural subunit arrA. The entire arr operon as well as the ars operon have also been identified in the fully annotated genome. A. oremlandii also transforms the organoarsenical 3-nitro-4-hydroxy benzene arsonic acid (roxarsone). Growth experiments and genomic analysis suggest that it couples the reduction of the nitro group of the organoarsenical to the oxidation of either lactate or fructose in a dissimilatory manner, generating ATP via a sodium dependent ATP synthase.